ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (11,895)
  • American Physical Society  (10,570)
  • Annual Reviews
  • Macmillian Magazines Ltd.
  • 2000-2004  (11,895)
  • 2003  (11,895)
  • Physics  (11,625)
  • Medicine  (1,126)
Collection
  • Articles  (11,895)
Years
  • 2000-2004  (11,895)
Year
Journal
  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 47-67 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Optical single transporter recording (OSTR) is an emerging technique for the fluorescence microscopic measurement of transport kinetics in membrane patches. Membranes are attached to transparent microarrays of cylindrical test compartments (TCs) ~0.1-100 mum in diameter and ~10-100 mum in depth. Transport across membrane patches that may contain single transporters or transporter populations is recorded by confocal microscopy. By these means transport of proteins through single nuclear pore complexes has been recorded at rates of 〈1 translocation/s. In addition to the high sensitivity in terms of measurable transport rates OSTR features unprecedented spatial selectivity and parallel processing. This article reviews the conceptual basis of OSTR and its realization. Applications to nuclear transport are summarized. The further development of OSTR is discussed and its extension to a diversity of transporters, including translocases and ATP-binding cassette (ABC) pumps, projected.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 93-114 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Since mid-1990, with cloning and identification of several families of natural killer (NK) receptors, research on NK cells began to receive appreciable attention. Determination of structures of NK cell surface receptors and their ligand complexes led to a fast growth in our understanding of the activation and ligand recognition by these receptors as well as their function in innate immunity. Functionally, NK cell surface receptors are divided into two groups, the inhibitory and the activating receptors. Structurally, they belong to either the immunoglobulin (Ig)-like receptor superfamily or the C-type lectin-like receptor (CTLR) superfamily. Their ligands are either members of class I major histocompatibility complexes (MHC) or homologs of class I MHC molecules. The inhibitory form of NK receptors provides the protective immunity through recognizing class I MHC molecules with self-peptides on healthy host cells. The activating, or the noninhibitory, NK receptors mediate the killing of tumor or virally infected cells through their specific ligand recognition. The structures of activating and inhibitory NK cell surface receptors and their complexes with the ligands determined to date, including killer immunoglobulin-like receptors (KIRs) and their complexes with HLA molecules, CD94, Ly49A, and its complex with H-2Dd, and NKG2D receptors and their complexes with class I MHC homologs, are reviewed here.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 161-182 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Recent years have witnessed a renaissance of fluorescence microscopy techniques and applications, from live-animal multiphoton confocal microscopy to single-molecule fluorescence spectroscopy and imaging in living cells. These achievements have been made possible not so much because of improvements in microscope design, but rather because of development of new detectors, accessible continuous wave and pulsed laser sources, sophisticated multiparameter analysis on one hand, and the development of new probes and labeling chemistries on the other. This review tracks the lineage of ideas and the evolution of thinking that have led to the actual developments, and presents a comprehensive overview of the field, with emphasis put on our laboratory's interest in single-molecule microscopy and spectroscopy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 135-159 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract The lamba integrase, or tyrosine-based family of site-specific recombinases, plays an important role in a variety of biological processes by inserting, excising, and inverting DNA segments. Flp, encoded by the yeast 2-mum plasmid, is the best-characterized eukaryotic member of this family and is responsible for maintaining the copy number of this plasmid. Over the past several years, structural and biochemical studies have shed light on the details of a common catalytic scheme utilized by these enzymes with interesting variations under different biological contexts. The emergence of new Flp structures and solution data provides insights not only into its unique mechanism of active site assembly and activity regulation but also into the specific contributions of certain protein residues to catalysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 285-310 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract The past decade has witnessed increasingly detailed insights into the structural mechanism of the bacteriorhodopsin photocycle. Concurrently, there has been much progress within our knowledge pertaining to the lipids of the purple membrane, including the discovery of new lipids and the overall effort to localize and identify each lipid within the purple membrane. Therefore, there is a need to classify this information to generalize the findings. We discuss the properties and roles of haloarchaeal lipids and present the structural data as individual case studies. Lipid-protein interactions are discussed in the context of structure-function relationships. A brief discussion of the possibility that bacteriorhodopsin functions as a light-driven inward hydroxide pump rather than an outward proton pump is also presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 375-397 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract G protein-coupled receptors (GPCRs) are integral membrane proteins that respond to environmental signals and initiate signal transduction pathways activating cellular processes. Rhodopsin is a GPCR found in rod cells in retina where it functions as a photopigment. Its molecular structure is known from cryo-electron microscopic and X-ray crystallographic studies, and this has reshaped many structure/function questions important in vision science. In addition, this first GPCR structure has provided a structural template for studies of other GPCRs, including many known drug targets. After presenting an overview of the major structural elements of rhodopsin, recent literature covering the use of the rhodopsin structure in analyzing other GPCRs will be summarized. Use of the rhodopsin structural model to understand the structure and function of other GPCRs provides strong evidence validating the structural model.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 399-424 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract The coupling of high-performance mass spectrometry instrumentation with highly efficient chromatographic and electrophoretic separations has enabled rapid qualitative and quantitative analysis of thousands of proteins from minute samples of biological materials. Here, we review recent progress in the development and application of mass spectrometry-based techniques for the qualitative and quantitative analysis of global proteome samples derived from whole cells, tissues, or organisms. Techniques such as multidimensional peptide and protein separations coupled with mass spectrometry, accurate mass measurement of peptides from global proteome digests, and mass spectrometric characterization of intact proteins hold great promise for characterization of highly complex protein mixtures. Advances in chemical tagging and isotope labeling techniques have enabled quantitative analysis of proteomes, and highly specific isolation strategies have been developed aimed at selective analysis of posttranslationally modified proteins.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 1-10 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 45-62 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Drag reduction in wall-bounded flows can be achieved by transverse motions imposed by passive means, e.g., riblets, or by external forcing, such as wall oscillation or transverse traveling-wave excitation. In this article, we review possible physical mechanisms responsible for turbulent drag reduction and corresponding near-wall flow modification.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 89-111 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this review we describe the aerodynamic problems that must be addressed in order to design a successful small aerial vehicle. The effects of Reynolds number and aspect ratio (AR) on the design and performance of fixed-wing vehicles are described. The boundary-layer behavior on airfoils is especially important in the design of vehicles in this flight regime. The results of a number of experimental boundary-layer studies, including the influence of laminar separation bubbles, are discussed. Several examples of small unmanned aerial vehicles (UAVs) in this regime are described. Also, a brief survey of analytical models for oscillating and flapping-wing propulsion is presented. These range from the earliest examples where quasi-steady, attached flow is assumed, to those that account for the unsteady shed vortex wake as well as flow separation and aeroelastic behavior of a flapping wing. Experiments that complemented the analysis and led to the design of a successful ornithopter are also described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 135-167 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The issue of the physical mechanism(s) that control the efficiency with which the density field in stably stratified fluid is mixed by turbulent processes has remained enigmatic. Similarly enigmatic has been an explanation of the numerical value of ~0.2, which is observed to characterize this efficiency experimentally. We review recent work on the turbulence transition in stratified parallel flows that demonstrates that this value is not only numerically predictable but also that it is expected to be a nonmonotonic function of the Richardson number that characterizes preturbulent stratification strength. This value of the mixing efficiency appears to be characteristic of the late-time behavior of the turbulent flow that develops after an initially laminar shear flow has undergone the transition to turbulence through an intermediate instability of Kelvin-Helmholtz type.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 373-412 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Recent small-scale turbulence observations allow the mixing regimes in lakes, reservoirs, and other enclosed basins to be categorized into the turbulent surface and bottom boundary layers as well as the comparably quiet interior. The surface layer consists of an energetic wave-affected thin zone at the very top and a law-of-the-wall layer right below, where the classical logarithmic-layer characteristic applies on average. Short-term current and dissipation profiles, however, deviate strongly from any steady state. In contrast, the quasi-steady bottom boundary layer behaves almost perfectly as a logarithmic layer, although periodic seiching modifies the structure in the details. The interior stratified turbulence is extremely weak, even though much of the mechanical energy is contained in baroclinic basin-scale seiching and Kelvin waves or inertial currents (large lakes). The transformation of large-scale motions to turbulence occurs mainly in the bottom boundary and not in the interior, where the local shear remains weak and the Richardson numbers are generally large.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 469-496 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Increasing urbanization and concern about sustainability and quality of life issues have produced considerable interest in flow and dispersion in urban areas. We address this subject at four scales: regional, city, neighborhood, and street. The flow is one over and through a complex array of structures. Most of the local fluid mechanical processes are understood; how these combine and what is the most appropriate framework to study and quantify the result is less clear. Extensive and structured experimental databases have been compiled recently in several laboratories. A number of major field experiments in urban areas have been completed very recently and more are planned. These have aided understanding as well as model development and evaluation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 295-315 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract It is classically assumed that the far field of a round turbulent jet discharging into quiescent fluid has a unique behavior characterized only by its momentum flux. However, there is now considerable evidence that different discharge conditions at the jet nozzle exit can give rise to very different far-field flows. Perhaps the most striking examples of these are the bifurcating and blooming jets produced by appropriate combinations of controlled axial and circumferential excitations at the nozzle exit. With the right excitations, a jet can be made to divide into two separate jets (bifurcating jet), each of which carries half the axial momentum and spreads in a manner similar to a single jet. Trifurcating jets can also be produced. Other excitations can produce blooming jets, in which the jet explodes into a shower of vortex rings, producing a far-field flow that is quite unlike a normal unexcited jet. Bifurcating and blooming jets exhibit much greater mixing than normal jets, suggesting possible applications in flow control. This article summarizes our work on bifurcating and blooming jets, which began with our discovery of them in the early 1980s and continued through the mid- 1990s. One of us (D.E.P.) continued exploration of flow control using excited jets, first at the McDonnell Douglas Corporation, and more recently at the Georgia Institute of Technology. The key to flow control is the manipulation of the large vortical structures in the near field of the jet. Ultimately this work, and that of others, led to full-scale testing of jet engine exhaust mixing control. There it was shown that the jet temperature downstream of the engine can be very significantly reduced by application of well-designed and easily implemented excitation at the engine discharge, thereby solving problems encountered during ground operations. Related jet control work by other investigators is included in this review.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 413-440 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The recent progress in three-dimensional boundary-layer stability and transition is reviewed. The material focuses on the crossflow instability that leads to transition on swept wings and rotating disks. Following a brief overview of instability mechanisms and the crossflow problem, a summary of the important findings of the 1990s is given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 183-206 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Cyclooxygenases-1 and -2 (COX-1 and COX-2, also known as prostaglandin H2 synthases-1 and -2) catalyze the committed step in prostaglandin synthesis. COX-1 and -2 are of particular interest because they are the major targets of nonsteroidal antiinflammatory drugs (NSAIDs) including aspirin, ibuprofen, and the new COX-2-selective inhibitors. Inhibition of the COXs with NSAIDs acutely reduces inflammation, pain, and fever, and long-term use of these drugs reduces the incidence of fatal thrombotic events, as well as the development of colon cancer and Alzheimer's disease. In this review, we examine how the structures of COXs relate mechanistically to cyclooxygenase and peroxidase catalysis and how alternative fatty acid substrates bind within the COX active site. We further examine how NSAIDs interact with COXs and how differences in the structure of COX-2 result in enhanced selectivity toward COX-2 inhibitors.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 425-443 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Understanding the action of enzymes on an atomistic level is one of the important aims of modern biophysics. This review describes the state of the art in addressing this challenge by simulating enzymatic reactions. It considers different modeling methods including the empirical valence bond (EVB) and more standard molecular orbital quantum mechanics/molecular mechanics (QM/MM) methods. The importance of proper configurational averaging of QM/MM energies is emphasized, pointing out that at present such averages are performed most effectively by the EVB method. It is clarified that all properly conducted simulation studies have identified electrostatic preorganization effects as the source of enzyme catalysis. It is argued that the ability to simulate enzymatic reactions also provides the chance to examine the importance of nonelectrostatic contributions and the validity of the corresponding proposals. In fact, simulation studies have indicated that prominent proposals such as desolvation, steric strain, near attack conformation, entropy traps, and coherent dynamics do not account for a major part of the catalytic power of enzymes. Finally, it is pointed out that although some of the issues are likely to remain controversial for some time, computer modeling approaches can provide a powerful tool for understanding enzyme catalysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 15-56 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: The galaxies of the Local Group serve as important laboratories for understanding the physics of massive stars. Here I discuss what is involved in identifying various kinds of massive stars in nearby galaxies: the hydrogen-burning O-type stars and their evolved He-burning evolutionary descendants, the luminous blue variables, red supergiants, and Wolf-Rayet stars. Primarily I review what our knowledge of the massive star population in nearby galaxies has taught us about stellar evolution and star formation. I show that the current generation of stellar evolutionary models do well at matching some of the observed features and provide a look at the sort of new observational data that will provide a benchmark against which new models can be evaluated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 169-189 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: The first law of theoretical physics, the Newtonian law of gravitation, relies on the concept of action at a distance. The success of this law led to the concept being applied to electricity and magnetism, which were next to be explored in depth. Here the action at a distance had a limited success and ultimately had to be abandoned in favor of the increasingly more popular field theory. Nevertheless, in the 1940s, an attempt was made to revive the concept of action at a distance in a relativistically invariant way by Wheeler & Feynman (1945, 1949). It inspired a series of investigations in both electrodynamics and gravity in which the field concept was not used but the interaction was described as taking place directly between particles. As it impinged very intimately on cosmology, Hoyle was keenly interested in it. This review discusses the work by Hoyle, the author, and others on the development of electrodynamics and gravitation as direct particle theories. In this review, the author discusses how the work was started and went through stages of increasing sophistication, e.g., extending the Wheeler-Feynman electrodynamics to curved spacetime, its consequences in different cosmologies, and the issues arising from its quantization. The resolution of ultraviolet divergences in quantum electrodynamics is also briefly discussed. The parallel development of a Machian theory of gravitation followed the lead from electrodynamics. In both theories one sees a strong link between the large-scale structure of the universe and local physics, as might be expected from an action-at-a-distance framework.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 343-390 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Targeted laboratory astrophysics measurements are being conducted to address the needs of X-ray astronomy. The measurements are producing large sets of reliable atomic data, which include ionization and recombination cross sections for charge balance calculations, as well as line lists, excitation cross sections, and dielectronic recombination rates for interpreting X-ray line formation. Additional experiments focus on resolving specific puzzles posed by astrophysical observations, as well as on calibrating existing and developing new X-ray line diagnostics. We discuss the types of data produced and illustrate how the laboratory measurements support such missions as ASCA, EUVE, Chandra, XMM, and ASTRO-E2.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 517-554 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Photoionized clouds are ubiquitous. They define the endpoints of stellar evolution (H II regions and planetary nebulae), constitute the interstellar and intergalactic media, and are found in high redshift quasars and star-forming galaxies. The spectra of these objects are dominated by emission lines that are sensitive to details of the emitting gas. These details include the microscopic atomic processes that cause the gas to glow; the density, composition, and temperature of the gas; and the radiation field of the central continuum source. Large-scale numerical codes that incorporate all the needed physics and predict the observed spectrum have become essential tools in understanding these objects. This article reviews the current status of the numerical simulations of emitting gas, with particular emphasis on photoionized clouds and the underlying simplicity that governs these nebulae; the types of questions that can be addressed by today's codes; and the big questions that remain unanswered.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 169-182 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The modern study of a crowd as a flowing continuum is a recent development. Distinct from a classical fluid because of the property that a crowd has the capacity to think, interesting new physical ideas are involved in its study. An appealing property of a crowd in motion is that the nonlinear, time-dependent, simultaneous equations representing a crowd are conformably mappable. This property makes many interesting applications analytically tractable. In this review examples are given in which the theory has been used to provide possible assistance in the annual Muslim Hajj, to understand the Battle of Agincourt, and, surprisingly, to locate barriers that actually increase the flow of pedestrians above that when there are no barriers present. Modern developments may help prevent some of the approximately two thousand deaths that annually occur in accidents owing to crowding.The field of crowd motion, that is, the field of "thinking fluids," is an intriguing area of research with great promise.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 267-293 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The recent avalanche of research activity in the field of granular matter has yielded much progress. The use of state-of-the-art (and other) computational and experimental methods has led to the discovery of new states and patterns and enabled detailed tests of theories and models. The application of statistical mechanical methods and phenomenology has contributed to the understanding of the microscopic a nd macroscopic properties of granular systems. Some previously open problems seem to be solved. Fluidized granular systems (rapid granular flows), recently referred to as granular gases, are often modeled by hydrodynamic equations of motion, some of which are based on systematic expansions applied to the pertinent Boltzmann equation. The undeniable success of granular hydrodynamics is somewhat surprising in view of the lack of scale separation in these systems and the neglect of certain correlations in most derivations of the hydrodynamic equations. Microstructures have been recognized as key features of granular gases; explanations for their existence have been proposed, and many of their properties elucidated. Granular-gas multistability can often be traced back to microstructure dynamics. In spite of these and other impressive advances, this field still poses serious challenges.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 317-340 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Recent advances in achieving textbook multigrid efficiency for fluid simulations are presented. Textbook multigrid efficiency is defined as attaining the solution to the governing system of equations in a computational work that is a small multiple of the operation counts associated with discretizing the system. Strategies are reviewed to attain this efficiency by exploiting the factorizability properties inherent to a range of fluid simulations, including the compressible Navier-Stokes equations. Factorizability is used to separate the elliptic and hyperbolic factors contributing to the target system; each of the factors can then be treated individually and optimally. Boundary regions and discontinuities are addressed with separate (local) treatments. New formulations and recent calculations demonstrating the attainment of textbook efficiency for aerodynamic simulations are shown.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 1-25 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Mass spectrometry has provided a powerful method for monitoring hydrogen exchange of protein backbone amides with deuterium from solvent. In comparison to popular NMR approaches, mass spectrometry has the advantages of higher sensitivity, wider coverage of sequence, and the ability to analyze larger proteins. Proteolytic fragmentation of proteins following the exchange reaction provides moderate structural resolution, in some cases enabling measurements from single amides. The technique has provided new insight into protein-protein and protein-ligand interfaces, as well as conformational changes during protein folding or denaturation. In addition, recent studies illustrate the utility of hydrogen exchange mass spectrometry toward detecting protein motions relevant to allostery, covalent modifications, and enzyme function.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 27-45 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Cations are bound to nucleic acids in a solvated state. High-resolution X-ray diffraction studies of oligonucleotides provide a detailed view of Mg2+, and occasionally other ions bound to DNA. In a survey of several such structures, certain general observations emerge. First, cations bind preferentially to the guanine base in the major groove or to phosphate group oxygen atoms. Second, cations interact with DNA most frequently via water molecules in their primary solvation shell, direct ion-DNA contacts being only rarely observed. Thus, the solvated ions should be viewed as hydrogen bond donors in addition to point charges. Finally, ion interaction sites are readily exchangeable: The same site may be occupied by any ion, including spermine, as well as by a water molecule.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 69-92 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Although protein function is thought to depend on flexibility, precisely how the dynamics of the molecule and its environment contribute to catalytic mechanisms is unclear. We review experimental and computational work relating to enzyme dynamics and function, including the role of solvent. The evidence suggests that fast motions on the 100 ps timescale, and any motions coupled to these, are not required for enzyme function. Proteins where the function is electron transfer, proton tunneling, or ligand binding may have different dynamical dependencies from those for enzymes, and enzymes with large turnover numbers may have different dynamical dependencies from those that turn over more slowly. The timescale differences between the fastest anharmonic fluctuations and the barrier-crossing rate point to the need to develop methods to resolve the range of motions present in enzymes on different time- and lengthscales.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 115-133 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract The OB-fold domain is a compact structural motif frequently used for nucleic acid recognition. Structural comparison of all OB-fold/nucleic acid complexes solved to date confirms the low degree of sequence similarity among members of this family while highlighting several structural sequence determinants common to most of these OB-folds. Loops connecting the secondary structural elements in the OB-fold core are extremely variable in length and in functional detail. However, certain features of ligand binding are conserved among OB-fold complexes, including the location of the binding surface, the polarity of the nucleic acid with respect to the OB-fold, and particular nucleic acid-protein interactions commonly used for recognition of single-stranded and unusually structured nucleic acids. Intriguingly, the observation of shared nucleic acid polarity may shed light on the longstanding question concerning OB-fold origins, indicating that it is unlikely that members of this family arose via convergent evolution.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 469-492 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract The observation of liquid-liquid immiscibility in cholesterol-phospholipid mixtures in monolayers and bilayers has opened a broad field of research into their physical chemistry. Some mixtures exhibit multiple immiscibilities. This unusual property has led to a thermodynamic model of "condensed complexes." These complexes are the consequence of an exothermic, reversible reaction between cholesterol and phospholipids. In this quantitative model the complexes are sometimes concentrated in a separate liquid phase. The phase separation into a complex-rich phase depends on membrane composition and intensive variables such as temperature. The properties of defined cholesterol-phospholipid mixtures provide a conceptual foundation for the exploration of a number of aspects of the biophysics and biochemistry of animal cell membranes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 1-14 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Astrophysics has been an important part of my personal and scientific life three times. The first was in 1938 when I did work on stellar energy production. The second was a joyful period nearly 30 years later when that work was rewarded with the Nobel Prize in physics. And the third has lasted over the time since my retirement in 1975 during which Gerry Brown and I have had a very satisfactory collaboration exploring various aspects of supernovae and, more recently, binary pairs.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 117-167 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Blueshifted absorption lines in the UV and X-ray spectra of active galaxies reveal the presence of massive outflows of ionized gas from their nuclei. The "intrinsic" UV and X-ray absorbers show large global covering factors of the central continuum source, and the inferred mass loss rates are comparable to the mass accretion rates. Many absorbers show variable ionic column densities, which are attributed to a combination of variable ionizing flux and motion of gas into and out of the line of sight. Detailed studies of the intrinsic absorbers, with the assistance of monitoring observations and photoionization models, provide constraints on their kinematics, physical conditions, and locations relative to the central continuum source, which range from the inner nucleus (~0.01 pc) to the galactic disk or halo (~10 kpc). Dynamical models that make use of thermal winds, radiation pressure, and/or hydromagnetic flows have reached a level of sophistication that permits comparisons with the observational constraints.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 465-515 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Old, cool white dwarfs convey valuable information about the early history of our Galaxy. They have been used to determine the age of the galactic disk, several open clusters, and a globular cluster. We review the current understanding of the physics of cool white dwarfs, including their mass distribution, chemical evolution, magnetism, and cooling. We also examine the role of white dwarfs as tracers of various stellar populations, both in terms of observational searches and theoretical models.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 429-463 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Giant planets have now been discovered around other stars, and it is only a matter of time until Earth-sized planets are detected. Whether any of these planets are suitable for life depends on their volatile abundances, especially water, and on their climates. Only planets within the liquid-water habitable zone (HZ) can support life on their surfaces and, thus, can be analyzed remotely to determine whether they are inhabited. Fortunately, current models predict that HZs are relatively wide around main-sequence stars not too different from our sun. This conclusion is based on studies of how our own planet has evolved over time. Earth's climate has remained conducive to life for the past 3.5 billion years or more, despite a large increase in solar luminosity, probably because of previous higher concentrations of CO2 and/or CH4. Both these gases are involved in negative feedback loops that help to stabilize the climate. In addition to these topics, we also briefly discuss the rise of atmospheric O2 and O3, along with their possible significance as indicators of life on other planets.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 57-115 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Stellar clusters are born embedded within giant molecular clouds (GMCs) and during their formation and early evolution are often only visible at infrared wavelengths, being heavily obscured by dust. Over the past 15 years advances in infrared detection capabilities have enabled the first systematic studies of embedded clusters in galactic molecular clouds. In this article we review the current state of empirical knowledge concerning these extremely young protocluster systems. From a survey of the literature we compile the first extensive catalog of galactic embedded clusters. We use the catalog to construct the mass function and estimate the birthrate for embedded clusters within ~2 kpc of the sun. We find that the embedded cluster birthrate exceeds that of visible open clusters by an order of magnitude or more indicating a high infant mortality rate for protocluster systems. Less than 4-7% of embedded clusters survive emergence from molecular clouds to become bound clusters of Pleiades age. The vast majority (90%) of stars that form in embedded clusters form in rich clusters of 100 or more members with masses in excess of 50 Mo. Moreover, observations of nearby cloud complexes indicate that embedded clusters account for a significant (70-90%) fraction of all stars formed in GMCs. We review the role of embedded clusters in investigating the nature of the initial mass function (IMF) that, in one nearby example, has been measured over the entire range of stellar and substellar mass, from OB stars to substellar objects near the deuterium burning limit. We also review the role embedded clusters play in the investigation of circumstellar disk evolution and the important constraints they provide for understanding the origin of planetary systems. Finally, we discuss current ideas concerning the origin and dynamical evolution of embedded clusters and the implications for the formation of bound open clusters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 391-427 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: In this contribution, a review is presented on the ample data obtained on post-AGB stars, both on the central stars and their circumstellar material. The fast evolutionary phase is characterized by a rapid change in the properties of the objects, but the variety is so large that there is yet no clear consensus on how the detailed studies of individual objects are linked together by evolutionary channels. The absence of strong molecular veiling in the photospheres of the central stars, together with a spread in intrinsic metallicity make post-AGB stars very useful in constraining AGB chemical evolutionary models. We discuss the surprisingly wide variety of chemical signatures observed. The onset in the creation process of the panoply of structures and shapes observed in planetary nebulae occurs during the short post-AGB evolution, but the physical nature of the processes involved is still badly understood. In the rapidly growing field of circumstellar mineralogy, post-AGB stars have their story to tell and also the molecular envelope changes significantly due to dilution and hardening of the stellar radiation. The real-time evolution of some objects suffering a late thermal flash is reviewed and their possible link to other hydrogen-deficient objects is discussed. Any review on stellar evolution has a section on binaries and this contribution is no exception because binaries make up a significant fraction of the post-AGB stars known to date.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 11-21 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Full-scale icing experiments and, therefore, certification time and cost can be significantly reduced by developing calculation methods to evaluate the aircraft and system performance for a wide range of icing conditions. This article summarizes calculation methods for icing that include ice accretion, ice system performance, and icing effects on aircraft.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 207-235 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Structural and thermodynamic characterizations of a variety of intra- and intermolecular interactions stabilizing/destabilizing protein systems represent a major part of multidisciplinary efforts aimed at solving the problems of protein folding and binding. To this end, volumetric techniques have been successfully used to gain insights into protein hydration and intraglobular packing. Despite the fact that the use of volumetric measurements in protein-related studies dates back to the 1950s, such measurements still represent a relatively untapped yet potentially informative means for tackling the problems of protein folding and binding. This notion has been further emphasized by recent advances in the development of highly sensitive volumetric instrumentation that has led to intensifying volumetric investigations of protein systems. This paper reviews the volumetric properties of proteins and their low-molecular-weight analogs, in particular, discussing the recent progress in the use of volumetric data for studying conformational transitions of proteins as well as protein-ligand, protein-protein, and protein-nucleic acid interactions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 237-256 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract This review focuses on cofactor-ligand and protein-protein interactions within the photosystem I reaction center. The topics include a description of the electron transfer cofactors, the mode of binding of the cofactors to protein-bound ligands, and a description of intraprotein contacts that ultimately allow photosystem I to be assembled (in cyanobacteria) from 96 chlorophylls, 22 carotenoids, 2 phylloquinones, 3 [4Fe-4S] clusters, and 12 polypeptides. During the 15 years that have elapsed from the first report of crystals to the atomic-resolution X-ray crystal structure, cofactor-ligand interactions and protein-protein interactions were systematically being explored by spectroscopic and genetic methods. This article charts the interplay between these disciplines and assesses how good the early insights were in light of the current structure of photosystem I.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 257-283 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Lipid raft microdomains were conceived as part of a mechanism for the intracellular trafficking of lipids and lipid-anchored proteins. The raft hypothesis is based on the behavior of defined lipid mixtures in liposomes and other model membranes. Experiments in these well-characterized systems led to operational definitions for lipid rafts in cell membranes. These definitions, detergent solubility to define components of rafts, and sensitivity to cholesterol deprivation to define raft functions implicated sphingolipid- and cholesterol-rich lipid rafts in many cell functions. Despite extensive work, the basis for raft formation in cell membranes and the size of rafts and their stability are all uncertain. Recent work converges on very small rafts 〈10 nm in diameter that may enlarge and stabilize when their constituents are cross-linked.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 335-373 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Molecular docking is an invaluable tool in modern drug discovery. This review focuses on methodological developments relevant to the field of molecular docking. The forces important in molecular recognition are reviewed and followed by a discussion of how different scoring functions account for these forces. More recent applications of computational chemistry tools involve library design and database screening. Last, we summarize several critical methodological issues that must be addressed in future developments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 311-334 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Acetylcholine binding protein (AChBP) has recently been identified from molluskan glial cells. Glial cells secrete it into cholinergic synapses, where it plays a role in modulating synaptic transmission. This novel mechanism resembles glia-dependent modulation of glutamate synapses, with several key differences. AChBP is a homolog of the ligand binding domain of the pentameric ligand-gated ion-channels. The crystal structure of AChBP provides the first high-resolution structure for this family of Cys-loop receptors. Nicotinic acetylcholine receptors and related ion-channels such as GABAA, serotonin 5HT3, and glycine can be interpreted in the light of the 2.7 A AChBP structure. The structural template provides critical details of the binding site and helps create models for toxin binding, mutational effects, and molecular gating.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biophysics and Biomolecular Structure 32 (2003), S. 445-468 
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Notes: Abstract Active transport of cations is achieved by a large family of ATP-dependent ion pumps, known as P-type ATPases. Various members of this family have been targets of structural and functional investigations for over four decades. Recently, atomic structures have been determined for Ca2+-ATPase by X-ray crystallography, which not only reveal the architecture of these molecules but also offer the opportunity to understand the structural mechanisms by which the energy of ATP is coupled to calcium transport across the membrane. This energy coupling is accomplished by large-scale conformational changes. The transmembrane domain undergoes plastic deformations under the influence of calcium binding at the transport site. Cytoplasmic domains undergo dramatic rigid-body movements that deliver substrates to the catalytic site and that establish new domain interfaces. By comparing various structures and correlating functional data, we can now begin to associate the chemical changes constituting the reaction cycle with structural changes in these domains.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 191-239 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: We review the origin, evolution, and physical nature of hot gas in elliptical galaxies and associated galaxy groups. Unanticipated recent X-ray observations with Chandra and XMM indicate much less cooling than previously expected. Consequently, many long-held assumptions must be reexamined or discarded and new approaches must be explored. Chief among these are the role of heating by active galactic nuclei, the influence of radio lobes on the hot gas, details of the cooling process, possible relation between the hot and colder gas in elliptical galaxies, and the complexities of stellar enrichment of the hot gas.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 241-289 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: This review surveys the observed properties of interstellar dust grains: the wavelength-dependent extinction of starlight, including absorption features, from UV to infrared; optical luminescence; infrared emission; microwave emission; optical, UV, and X-ray scattering by dust; and polarization of starlight and of infrared emission. The relationship between presolar grains in meteorites and the interstellar grain population is discussed. Candidate grain materials and abundance constraints are considered. A dust model consisting of amorphous silicate grains, graphite grains, and polycyclic aromatic hydrocarbons is compared with observed emission and scattering. Some issues concerning evolution of interstellar dust are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 555-597 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: The status of our current understanding of angular momentum transport in accretion disks is reviewed. The last decade has seen a dramatic increase both in the recognition of key physical processes and in our ability to carry through direct numerical simulations of turbulent flow. Magnetic fields have at once powerful and subtle influences on the behavior of (sufficiently) ionized gas, rendering them directly unstable to free energy gradients. Outwardly descreasing angular velocity profiles are unstable. The breakdown of Keplerian rotation into MHD turbulence may be studied in some numerical detail, and key transport coefficients may be evaluated. Chandra observations of the Galactic Center support the existence of low luminosity accretion, which may ultimately prove amenable to global three-dimensional numerical simulation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 599-643 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Helioseismology has transformed our knowledge of the Sun's rotation. Earlier studies revealed the Sun's surface rotation, but now a detailed observational picture has been built up of the internal rotation of our nearest star. Unlike the predictions of stellar-evolution models, the radiative interior is found to rotate roughly uniformly. The rotation within the convection zone is also very different from prior expectations, which had been that the rotation rate would depend primarily on the distance from the rotation axis. Layers of rotational shear have been discovered at the base of the convection zone and in the subphotospheric layers. Studies of the time variation of rotation have uncovered zonal-flow bands, extending through a substantial fraction of the convection zone, which migrate over the course of the solar cycle, and there are hints of other temporal variations and of a jet-like structure. At the same time, building on earlier work with mean-field models, researchers have made great progress in supercomputer simulations of the intricate interplay between turbulent convection and rotation in the Sun's interior. Such studies are beginning to transform our understanding of how rotation organizes itself in a stellar interior.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 291-342 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: The launches of the Chandra X-Ray Observatory in June 1999 and the XMM-Newton Observatory in December 1999 opened a new era in X-ray astronomy. Both of these missions incorporate novel diffraction grating spectrometers that are providing the first high-resolution X-ray spectra of most classes of astrophysical sources. The spectra obtained to date exhibit a wealth of discrete detail, yielding sensitive constraints on physical conditions in the emitting plasmas. We review the essential characteristics of these instruments, the basics of X-ray spectral formation in cosmic sources, and the exciting new results that have emerged from Chandra and XMM-Newton grating observations of a wide variety of astrophysical systems.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 41 (2003), S. 645-668 
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Weak gravitational lensing provides a unique method to map directly the distribution of dark matter in the universe and to measure cosmological parameters. This cosmic-shear technique is based on the measurement of the weak distortions that lensing induces in the shape of background galaxies as photons travel through large-scale structures. This technique is now widely used to measure the mass distribution of galaxy clusters and has recently been detected in random regions of the sky. In this review, we present the theory and observational status of cosmic shear. We describe the principles of weak lensing and the predictions for the shear statistics in favored cosmological models. Next, we review the current measurements of cosmic shear and show how they constrain cosmological parameters. We then describe the prospects offered by upcoming and future cosmic-shear surveys as well as the technical challenges that have to be met for the promises of cosmic shear to be fully realized.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 23-43 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The more violent impacts of water waves on walls create velocities and pressures having magnitudes much larger than those associated with the propagation of ordinary waves under gravity. Insight into these effects has been gained by irrotational-flow computations and by investigating the role of entrained and trapped air in wave impacts. This review focuses on the results of theoretical work, making particular note of the value of considering pressure impulse, and highlights the aspects that are poorly understood.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 63-88 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper reviews recent advances in our understanding of the origin and hierarchy of organized flow structures in fluidized beds, distinction between bubbling and nonbubbling systems, and stages of bubble evolution. Experimental data and theory suggest that, at high particle concentrations, the particle-phase pressure arising from flow-induced velocity fluctuations decreases with increasing concentration of particles. This, in turn, implies that nonhydrodynamic stresses must be present to impart stability to a uniformly fluidized bed at very high particle concentrations. There is ample evidence to support an argument that, in commonly encountered gas-fluidized beds, yield stresses associated with enduring particle networks are present in the window of stable bed expansion, where the particles are essentially immobile until bubbling commences. However, some recent data on gas-fluidized beds of agglomerates of cohesive particles suggest that there exists a window of bed expansion where the bed does manifest a smooth appearance to the naked eye and the particles are mobile; at higher gas velocities the bed bubbles visibly. The mechanics of such beds remain to be fully explained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 113-133 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A review is given of the stability of complex fluids subject to homogeneous states of shearing, a research field that is scarcely two decades old. For the benefit of fluid mechanicians, a brief, somewhat historical overview is presented of material instability in elastoplastic solids, where one finds a considerable body of experiment and a rich source of theoretical concepts including Hadamard instability, strain localization, and nonlocal constitutive models. A survey is then given of recent theoretical and experimental studies of instability with shear banding in various complex fluids, including micellar solutions, particulate suspensions, and rapidly sheared granular media. Various stability analyses are encapsulated in a mathematical dynamical-systems model for constitutive equations of the rate-type, and a general linear-stability theory is given for viscoelastic fluids in unbounded homogeneous shear flows. A general form of (Kelvin) wave-vector stretching is shown to play a key role in the growth of Fourier modes, as illustrated by recent computations for granular shear flow. The Fourier description also provides an explicit representation of higher-gradient (nonlocal) effects as higher-order powers of wave number.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 183-227 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Turbulence is ubiquitous in atmospheric clouds, which have enormous turbulence Reynolds numbers owing to the large range of spatial scales present. Indeed, the ratio of energy-containing and dissipative length scales is on the order of 105 for a typical convective cloud, with a corresponding large-eddy Reynolds number on the order of 106 to 107. A characteristic trait of high-Reynolds-number turbulence is strong intermittency in energy dissipation, Lagrangian acceleration, and scalar gradients at small scales. Microscale properties of clouds are determined to a great extent by thermodynamic and fluid-mechanical interactions between droplets and the surrounding air, all of which take place at small spatial scales. Furthermore, these microscale properties of clouds affect the efficiency with which clouds produce rain as well as the nature of their interaction with atmospheric radiation and chemical species. It is expected, therefore, that fine-scale turbulence is of direct importance to the evolution of, for example, the droplet size distribution in a cloud. In general, there are two levels of interaction that are considered in this review: (a) the growth of cloud droplets by condensation and (b) the growth of large drops through the collision and coalescence of cloud droplets. Recent research suggests that the influence of fine-scale turbulence on the condensation process may be limited, although several possible mechanisms have not been studied in detail in the laboratory or the field. There is a growing consensus, however, that the collision rate and collision efficiency of cloud droplets can be increased by turbulence-particle interactions. Adding strength to this notion is the growing experimental evidence for droplet clustering at centimeter scales and below, most likely due to strong fluid accelerations in turbulent clouds. Both types of interaction, condensation and collision-coalescence, remain open areas of research with many possible implications for the physics of atmospheric clouds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 229-265 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This review describes some of the important developments in the numerical investigation of transition to turbulence in wall-bounded and free shear flows during the past decade. The evolution of numerical techniques and models as well as the advances in our theoretical understanding of the physics of laminar-turbulent transition that were achieved using these tools are described. For wall-bounded flows, particular emphasis is placed on investigations studying various scenarios of "bypass transition" in flows that are asymptotically stable. A brief review of investigations into receptivity and control of transitional flows is included.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 341-372 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We provide an overview of level set methods, introduced by Osher and Sethian, for computing the solution to fluid-interface problems. These are computational techniques that rely on an implicit formulation of the interface, represented through a time-dependent initial-value partial-differential equation. We discuss the essential ideas behind the techniques, the coupling of these techniques to finite-difference methods for incompressible and compressible flow, and a collection of applications including two-phase flow, ship hydrodynamics, and ink-jet-printhead design.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 441-468 
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We review the most important theoretical and numerical results obtained in the realm of shell models for the energy-turbulent cascade. We mainly focus here on those results that had or will have some impact on the fluid-dynamics community. In particular, we address the problem of small-scale intermittency by discussing energy-helicity interactions, energy-dissipation multifractality, and universality of intermittency, i.e., independence of anomalous scaling exponents from large-scale forcing and boundary conditions. A multifractal-based description of multiscale and multitime correlation functions in turbulence is also presented. Finally, we also briefly review the analytical difficulties, and hopes, of calculating anomalous exponents.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 29-70 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract CD8 T cells respond to viral infections but also participate in defense against bacterial and protozoal infections. In the last few years, as new methods to accurately quantify and characterize pathogen-specific CD8 T cells have become available, our understanding of in vivo T cell responses has increased dramatically. Pathogen-specific T cells, once thought to be quite rare following infection, are now known to be present at very high frequencies, particularly in peripheral, nonlymphoid tissues. With the ability to visualize in vivo CD8 T cell responses has come the recognition that T cell expansion is programmed and, to a great extent, independent of antigen concentrations. Comparison of CD8 T cell responses to different pathogens also highlights the intricate relationship between microbially induced innate inflammatory responses and the kinetics, magnitude, and character of long-term T cell responses. This review describes recent progress in some of the major murine models of CD8 T cell-mediated immunity to viral, bacterial, and protozoal infection.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 139-176 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract A functional immune system requires the selection of T lymphocytes expressing receptors that are major histocompatibility complex restricted but tolerant to self-antigens. This selection occurs predominantly in the thymus, where lymphocyte precursors first assemble a surface receptor. In this review we summarize the current state of the field regarding the natural ligands and molecular factors required for positive and negative selection and discuss a model for how these disparate outcomes can be signaled via the same receptor. We also discuss emerging data on the selection of regulatory T cells. Such cells require a high-affinity interaction with self-antigens, yet differentiate into regulatory cells instead of being eliminated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 265-304 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract In the absence of antiretroviral treatment, HIV-1 establishes a chronic, progressive infection of the human immune system that invariably, over the course of years, leads to its destruction and fatal immunodeficiency. Paradoxically, while viral replication is extensive throughout the course of infection, deterioration of conventional measures of immunity is slow, including the characteristic loss of CD4+ T cells that is thought to play a key role in the development of immunodeficiency. This conundrum suggests that CD4+ T cell-directed viral cytopathicity alone cannot explain the course of disease. Indeed, recent advances now indicate that HIV-1 pathogenesis is likely to result from a complex interplay between the virus and the immune system, particularly the mechanisms responsible for T cell homeostasis and regeneration. We review these data and present a model of HIV-1 pathogenesis in which the protracted loss of CD4+ T cells results from early viral destruction of selected memory T cell populations, followed by a combination of profound increases in overall memory T cell turnover, damage to the thymus and other lymphoid tissues, and physiological limitations in peripheral CD4+ T cell renewal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 425-456 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract IL-13 was first recognized for its effects on B cells and monocytes, where it upregulated class II expression, promoted IgE class switching and inhibited inflammatory cytokine production. It was also thought to be functionally redundant with IL-4. However, studies conducted with knockout mice, neutralizing antibodies, and novel antagonists demonstrate that IL-13 possesses several unique effector functions that distinguish it from IL-4. Resistance to most gastrointestinal nematodes is mediated by type-2 cytokine responses, in which IL-13 plays a dominant role. By regulating cell-mediated immunity, IL-13 modulates resistance to intracellular organisms including Leishmania major, Leishmania mexicana, and Listeria monocytogenes. In the lung, IL-13 is the central mediator of allergic asthma, where it regulates eosinophilic inflammation, mucus secretion, and airway hyperresponsiveness. Manipulation of IL-13 effector function may also prove useful in the treatment of some cancers like B-cell chronic lymphocytic leukemia and Hodgkin's disease, where IL-13 modulates apoptosis or tumor cell growth. IL-13 can also inhibit tumor immunosurveillance. As such, inhibitors of IL-13 might be effective as cancer immunotherapeutics by boosting type-1-associated anti-tumor defenses. Finally, IL-13 was revealed as a potent mediator of tissue fibrosis in both schistosomiasis and asthma, which indicates that it is a key regulator of the extracellular matrix. The mechanisms that regulate IL-13 production and/or function have also been investigated, and IL-4, IL-12, IL-18, IFN-gamma, IL-10, TGF-beta, TNF-alpha, and the IL-4/IL-13 receptor complex play important roles. This review highlights the effector functions of IL-13 and describes multiple pathways for modulating its activity in vivo.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 547-578 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Collectins and ficolins, present in plasma and on mucosal surfaces, are humoral molecules of the innate immune systems, which recognize pathogen-associated molecular patterns. The human collectins, mannan-binding lectin (MBL) and surfactant protein A and D (SP-A and SP-D), are oligomeric proteins composed of carbohydrate-recognition domains (CRDs) attached to collagenous regions and are thus structurally similar to the ficolins, L-ficolin, M-ficolin, and H-ficolin. However, they make use of different CRD structures: C-type lectin domains for the collectins and fibrinogen-like domains for the ficolins. Upon recognition of the infectious agent, MBL and the ficolins initiate the lectin pathway of complement activation through attached serine proteases (MASPs), whereas SP-A and SP-D rely on other effector mechanisms: direct opsonization, neutralization, and agglutination. This limits the infection and concurrently orchestrates the subsequent adaptive immune response. Deficiencies of the proteins may predispose to infections or other complications, e.g., reperfusion injuries or autoimmune diseases. Structure, function, clinical implications, and phylogeny are reviewed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 713-758 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract The T helper lymphocyte is responsible for orchestrating the appropriate immune response to a wide variety of pathogens. The recognition of the polarized T helper cell subsets Th1 and Th2 has led to an understanding of the role of these cells in coordinating a variety of immune responses, both in responses to pathogens and in autoimmune and allergic disease. Here, we discuss the mechanisms that control lineage commitment to the Th1 phenotype. What has recently emerged is a rich understanding of the cytokines, receptors, signal transduction pathways, and transcription factors involved in Th1 differentiation. Although the picture is still incomplete, the basic pathways leading to Th1 differentiation can now be understood in in vitro and a number of infection and disease models.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 685-711 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Dendritic cells (DCs) have several functions in innate and adaptive immunity. In addition, there is increasing evidence that DCs in situ induce antigen-specific unresponsiveness or tolerance in central lymphoid organs and in the periphery. In the thymus DCs generate tolerance by deleting self-reactive T cells. In peripheral lymphoid organs DCs also induce tolerance to antigens captured by receptors that mediate efficient uptake of proteins and dying cells. Uptake by these receptors leads to the constitutive presentation of antigens on major histocompatibility complex (MHC) class I and II products. In the steady state the targeting of DC antigen capture receptors with low doses of antigens leads to deletion of the corresponding T cells and unresponsiveness to antigenic rechallenge with strong adjuvants. In contrast, if a stimulus for DC maturation is coadministered with the antigen, the mice develop immunity, including interferon-gamma-secreting effector T cells and memory T cells. There is also new evidence that DCs can contribute to the expansion and differentiation of T cells that regulate or suppress other immune T cells. One possibility is that distinct developmental stages and subsets of DCs and T cells can account for the different pathways to peripheral tolerance, such as deletion or suppression. We suggest that several clinical situations, including autoimmunity and certain infectious diseases, can be influenced by the antigen-specific tolerogenic role of DCs.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 21 (2003), S. 841-894 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract B cell chronic lymphocytic leukemia (B-CLL) is an accumulative disease of slowly proliferating CD5+ B lymphocytes that develops in the aging population. Whereas some patients with B-CLL have an indolent course and die after many years from unrelated causes, others progress very rapidly and succumb within a few years from this currently incurable leukemia. Over the past decade studies of the structure and function of the B cell antigen receptor (BCR) used by these leukemic cells have helped redefine the nature of this disease. In this review we summarize and reinterpret several aspects of these BCR-related studies and how they might relate to the disease. In particular, we address the ability of antigens to select out and drive B cell clones from the normal state to overt leukemic cells by binding to BCRs that are relatively unique and characteristic of B-CLL cells. The differential capacity of some B-CLL cases to continue to transduce signals through the BCR during the leukemic phase and the consequences for the in vivo biology of the leukemic clone is also considered. Finally, we discuss current and emerging views of the cellular origin of B-CLL cells and the differentiation pathways down which we believe these cells progress.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 81-101 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract The ability of the myocardium to successfully compensate for and adapt to environmental stress ultimately determines whether the heart will decompensate and fail or maintain preserved function. Despite the importance of the myocardial response to environmental stress, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. In the present review we summarize recent experimental material suggesting that the cytokines expressed within the myocardium in response to environmental injury, namely tumor necrosis factor (TNF), interleukin-1 (IL-1), and the interleukin-6 (IL-6) family, play an important role in initiating and integrating homeostatic responses. However, these stress-activated cytokines all have the potential to produce cardiac decompensation when expressed at sufficiently high concentrations. Accordingly, the theme to emerge from this review is that the short-term expression of stress-activated cytokines within the heart may be an adaptive response to stress, whereas long-term expression of these molecules may be frankly maladaptive by producing cardiac decompensation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 161-175 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Conventional kinesin is the prototypic member of a family of diverse proteins that use the chemical energy of ATP hydrolysis to generate force and move along microtubules. These proteins, which are involved in a wide range of cellular functions, have been identified in protozoa, fungi, plants, and animals and possess a high degree of sequence conservation among species in their motor domains. The biochemical properties of kinesin and its homologues, in conjunction with the recently solved three-dimensional structures of several kinesin motors, have contributed to our understanding of the mechanism of kinesin movement along microtubules. We discuss several models for movement, including the hand-over-hand, inchworm, and biased diffusion models of processive movement, as well as models of nonprocessive movement.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 231-259 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract DNA microarray technology is revolutionizing many aspects of biological research, allowing the expression of many thousands of gene transcripts to be monitored simultaneously. This provides powerful tools for the genome-wide correlation of gene transcript levels with physiological responses and alterations in physiological states. To date, microarray analyses have been applied almost exclusively to a few model species for which the abundant gene sequence data permit the fabrication of whole-genome microarrays. However, many interesting physiological traits and responses are poorly expressed or absent in model species and may be better illustrated in nonmodel organisms. Comparative approaches to understanding function traditionally focus on species that by virtue of their unusual adaptations, lifestyles, and phylogeny are particularly suited to address a specific biological process or problem. In this review, we show that microarray technology can be successfully applied to these nonmodel species and used to generate new insights of comparative and evolutionary significance into animal function.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 333-347 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Here we explore the physiologic role of leptin as a liporegulatory hormone responsible for maintaining intracellular homeostasis in the face of wide variations in caloric intake. Normally, rats can tolerate a 60% fat diet because 96% of the surplus fat is deposited in adipocytes. In contrast, when leptin is congenitally absent or inactive, even on a normal diet, unutilized dietary fat is deposited in nonadipose tissues, causing dysfunction (lipotoxicity) and possible cell death (lipoapoptosis). We theorize that in diet-induced obesity, acquired leptin resistance may also develop as the result of increase in certain leptin resistance factors. Acquired leptin resistance occurs in aging, obesity, Cushing's syndrome, and acquired lipodystrophy, and preliminary evidence suggests that ectopic lipid deposition is increased. We speculate that the metabolic syndrome may be the human equivalent of the lipotoxic syndrome of rodents.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 383-400 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract The regulation of acid secretion in the stomach involves a complex network of factors that stimulate secretion in response to the ingestion of a meal and maintain homeostasis of gastric pH. Genetically engineered mouse models have provided a new opportunity to investigate the importance and function of specific molecules and pathways involved in the regulation of acid secretion. Mouse mutants with disruptions in the three major stimulatory pathways for acid secretion in parietal cells, gastrin, histamine, and acetylcholine, have been generated. Disruption of the gastrin pathway results in a major impairment in both basal and induced acid secretion. Histamine and acetylcholine pathway mutants also have significant alterations in acid secretion, although the impairment does not appear to be as severe as in gastrin pathway mutants, perhaps due in part to the hypergastrinemia that occurs. Mice with a disruption in the somatostatin pathway have increased gastric acid secretion, which confirms an important negative regulatory role for this factor. This review discusses these genetically engineered mouse models, as well as others, that provide insight into the complex regulation of in vivo gastric acid secretion. The regulation of growth and cellular morphology of the stomach in these mouse models is also presented. In addition, transgene promoters that are expressed in the gastric epithelium are discussed because these promoters will be important tools to alter cellular physiology in new mouse models in the future.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 429-452 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Mechanosensation has been studied for decades, but understanding of its molecular mechanism is only now emerging from studies in Caenorhabditis elegans and Drosophila melanogaster. In both cases, the entry point proved to be genetic screens that allowed molecules needed for mechanosensation to be identified without any prior understanding of the likely components. In C. elegans, genetic screens revealed molecules needed for touch sensation along the body wall and other regions of force sensitivity. Members of two extensive membrane protein families have emerged as candidate sensory mechanotransduction channels: mec-4 and mec-10, which encode amiloride-sensitive channels (ASCs or DEG/ENaCs), and osm-9, which encodes a TRP ion channel. There are roughly 50 other members of these families whose functions in C. elegans are unknown. This article classifies these channels in C. elegans, with an emphasis on insights into their function derived from mutation. We also review the neuronal cell types in which these channels might be expressed and mediate mechanotransduction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 23-43 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract To most people, concerns over the link between lipids and cardiovascular health most likely end with monitoring their daily consumption of dietary fats. However, it has become increasingly clear that, in addition to effects on adult cardiovascular physiology, lipids also play key roles in the formation of a functioning cardiovascular system. The lysophospholipids, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), have come to the forefront as developmental and physiological regulators of the cardiovascular system. In this review, we discuss the function of the G protein-coupled receptors responsible for transducing LPA and S1P signals during development of the vertebrate cardiovascular system, focusing first on their role in angiogenesis and then on their function during embryonic development.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 133-159 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Recent advances-both experimental and theoretical-provide a tentative image of the structures in Ca channels that make them exceptionally selective. The image is very different from K channels, which obtain high selectivity with a rigid pore that tightly fits K+ ions and is lined by carbonyl oxygens of the polypeptide backbone. Ca channels rely on four glutamate residues (the EEEE locus), whose carboxyl side chains likely reach into the pore lumen to interact with passing Ca2+ ions. The structure is thought to be flexible, tightly binding a single Ca2+ ion in order to block Na+ flux but rearranging to interact with multiple Ca2+ ions to allow Ca2+ flux. The four glutamates are not equivalent, a fact that seems important for Ca2+ permeation. This review describes the experimental evidence that leads to these conclusions and the attempts by theorists to explain the combination of high selectivity and high flux that characterizes Ca channels.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 177-201 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract This review addresses the mechanisms by which mitochondrial structure and function are regulated, with a focus on vertebrate muscle. We consider the adaptive remodeling that arises during physiological transitions such as differentiation, development, and contractile activity. Parallels are drawn between such phenotypic changes and the pattern of change arising over evolutionary time, as suggested by interspecies comparisons. We address the physiological and evolutionary relationships between ATP production, thermogenesis, and superoxide generation in the context of mitochondrial function. Our discussion of mitochondrial structure focuses on the regulation of membrane composition and maintenance of the three-dimensional reticulum. Current studies of mitochondrial biogenesis strive to integrate muscle functional parameters with signal transduction and molecular genetics, providing insight into the origins of variation arising between physiological states, fiber types, and species.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 313-332 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract To examine the role of the insulin receptor in fuel homeostasis, we and others have carried out genetic ablation studies in mice. Mice lacking insulin receptors are born with normal features, but develop early postnatal diabetes and die of ketoacidosis. In contrast, mice lacking insulin receptors in specific cell types as a result of conditional mutagenesis develop mild metabolic and reproductive abnormalities. These experiments have uncovered novel functions of insulin receptors in tissues such as brain and pancreatic beta-cells. Combined knockout studies of insulin and Igf1 receptors indicate that the insulin receptor also promotes embryonic growth. Experimental crosses of mice with insulin receptor haploinsufficiency have been instrumental to the genetic analysis of insulin action by enabling us to assign specific roles to different insulin receptor substrates and identify novel elements in insulin signaling.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Earth and Planetary Sciences 31 (2003), S. 555-577 
    ISSN: 0084-6597
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract We present preliminary evidence for a ~10,000-year earthquake record from two major fault systems based on sediment cores collected along the continental margins of western North America. New stratigraphic evidence from Cascadia demonstrates that 13 earthquakes ruptured the entire margin from Vancouver Island to at least the California border since the eruption of the Mazama ash 7700 years ago. The 13 events above this prominent stratigraphic marker have an average repeat time of 600 years, and the youngest event ~300 years ago coincides with the coastal record. We also extend the record of past earthquakes to the base of the Holocene (at least 9800 years ago), during which 18 events correlate along the same region. The sequence of Holocene events in Cascadia appears to contain a repeating pattern of events, a tantalizing first look at what may be the long-term behavior of a major fault system. The northern California margin cores show a cyclic record of turbidite beds that may represent Holocene earthquakes on the northern segment of the San Andreas Fault. Preliminary results are in reasonably good agreement with onshore paleoseismic data that indicate an age for the penultimate event in the mid-1600s at several sites and the most likely age for the third event of ~AD 1300.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Earth and Planetary Sciences 31 (2003), S. 399-427 
    ISSN: 0084-6597
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract Considerable progress has been made over the past decade in understanding the static rheological properties of granitic magmas in the continental crust. Changes in H2O content, CO2 content, and oxidation state of the interstitial melt phase have been identified as important compositional factors governing the rheodynamic behavior of the solid/fluid mixture. Although the strengths of granitic magmas over the crystallization interval are still poorly constrained, theoretical investigations suggest that during magma ascent, yield strengths of the order of 9 kPa are required to completely retard the upward flow in meter-wide conduits. In low Bagnold number magma suspensions with moderate crystal contents (solidosities 0.1 〈=phi〈= 0.3), viscous fluctuations may lead to flow differentiation by shear-enhanced diffusion. AMS and microstructural studies support the idea that granite plutons are intruded as crystal-poor liquids (phi〈= 50%), with fabric and foliation development restricted to the final stages of emplacement. If so, then these fabrics contain no information on the ascent (vertical transport) history of the magma. Deformation of a magmatic mush during pluton emplacement can enhance significantly the pressure gradient in the melt, resulting in a range of local macroscopic flow structures, including layering, crystal alignment, and other mechanical instabilities such as shear zones. As the suspension viscosity varies with stress rate, it is not clear how the timing of proposed rheological transitions formulated from simple equations for static magma suspensions applies to mixtures undergoing shear. New theories of magmas as multiphase flows are required if the full complexity of granitic magma rheology is to be resolved.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Earth and Planetary Sciences 31 (2003), S. 579-594 
    ISSN: 0084-6597
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract Is El Nino one phase of a continual, self-sustaining natural mode of the coupled ocean-atmosphere that has La Nina as the complementary phase? Or is El Nino a temporary departure from "normal" conditions "triggered" by a random disturbance such as a burst of westerly winds? A growing body of evidence-stability analyses, studies of the energetics, simulations that reproduce the statistics of sea surface temperature variations in the eastern equatorial Pacific-indicates that reality corresponds to a compromise between these two possibilities: The observed Southern Oscillation between El Nino and La Nina corresponds to a weakly damped mode that is sustained by random disturbances. This means that the predictability of El Nino is limited by the continual presence of "noise" so that forecasts should be probabilistic. The Southern Oscillation is also subject to decadal modulations. How it will be influenced by global warming is a matter of considerable uncertainty.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 26 (2003), S. 31-55 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Behavioral, anatomical, and physiological approaches can be integrated in the study of sound localization in barn owls. Space representation in owls provides a useful example for discussion of place and ensemble coding. Selectivity for space is broad and ambiguous in low-order neurons. Parallel pathways for binaural cues and for different frequency bands converge on high-order space-specific neurons, which encode space more precisely. An ensemble of broadly tuned place-coding neurons may converge on a single high-order neuron to create an improved labeled line. Thus, the two coding schemes are not alternate methods. Owls can localize sounds by using either the isomorphic map of auditory space in the midbrain or forebrain neural networks in which space is not mapped.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 26 (2003), S. 81-104 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Alzheimer's disease, Parkinson's disease, and motor neuron disease share a propensity to occur with increasing age and as either a sporadic or a familial disorder. A number of behavioral and environmental risk factors have been proposed for each disorder, but most associations lack consistency and specificity. Over the last decade the remarkable frequency of these disorders has become apparent, and the identification of mutations in genes has provided the means to understand their pathogenesis. Better and more accurate means to characterize and diagnose these diseases has greatly facilitated analytic epidemiology. The analysis of behavioral and genetic factors that may lower disease risk has led to clinical trials that are either in progress or being planned with the aim of preventing these disorders.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 26 (2003), S. 57-80 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract A significant number of individuals have unexplained difficulties with acquiring normal speech and language, despite adequate intelligence and environmental stimulation. Although developmental disorders of speech and language are heritable, the genetic basis is likely to involve several, possibly many, different risk factors. Investigations of a unique three-generation family showing monogenic inheritance of speech and language deficits led to the isolation of the first such gene on chromosome 7, which encodes a transcription factor known as FOXP2. Disruption of this gene causes a rare severe speech and language disorder but does not appear to be involved in more common forms of language impairment. Recent genome-wide scans have identified at least four chromosomal regions that may harbor genes influencing the latter, on chromosomes 2, 13, 16, and 19. The molecular genetic approach has potential for dissecting neurological pathways underlying speech and language disorders, but such investigations are only just beginning.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 26 (2003), S. 133-179 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Over the past two decades significant progress has been made toward understanding the neural basis of primate decision making, the biological process that combines sensory data with stored information to select and execute behavioral responses. The most striking progress in this area has been made in studies of visual-saccadic decision making, a system that is becoming a model for understanding decision making in general. In this system, theoretical models of efficient decision making developed in the social sciences are beginning to be used to describe the computations the brain must perform when it connects sensation and action. Guided in part by these economic models, neurophysiologists have been able to describe neuronal activity recorded from the brains of awake-behaving primates during actual decision making. These recent studies have examined the neural basis of decisions, ranging from those made in predictable sensorimotor tasks to those unpredictable decisions made when animals are engaged in strategic conflict. All of these experiments seem to describe a surprisingly well-integrated set of physiological mechanisms that can account for a broad range of behavioral phenomena. This review presents many of these recent studies within the emerging neuroeconomic framework for understanding primate decision making.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 26 (2003), S. 207-238 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Immunoglobulin superfamily (IgSF) proteins are implicated in diverse steps of brain development, including neuronal migration, axon pathfinding, target recognition and synapse formation, as well as in the maintenance and function of neuronal networks in the adult. We provide here a review of recent findings on the diversity and the role of transmembrane and secreted members of IgSF proteins in the nervous system. We illustrate that the complexity of IgSF protein function results from various different levels of regulation including regulation of gene expression, protein localization, and protein interactions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 26 (2003), S. 627-656 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract A number of approaches have been taken to recreate and to study the role of genes associated with human neurodegenerative diseases in the model organism Drosophila. These studies encompass the polyglutamine diseases, Parkinson's disease, Alzheimer's disease, and tau-associated pathologies. The findings highlight Drosophila as an important model system in which to study the fundamental pathways influenced by these genes and have led to new insights into aspects of pathogenesis and modifier mechanisms.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 29-56 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Magnetic resonance imaging (MRI) is widely applied for functional imaging of the microcirculation and for functional and structural studies of the microvasculature. The interest in the capabilities of MRI in noninvasively monitoring changes in vascular structure and function expanded over the past years, with specific efforts directed toward the development of novel imaging methods for quantification of angiogenesis. Molecular imaging approaches hold promise for further expansion of the ability to characterize the microvasculature. Exciting applications for MRI are emerging in the study of the biology of microvessels and in the evaluation of potential pharmaceutical modulators of vascular function and development, and preclinical MRI tools can serve for the design of mechanism-of-action-based noninvasive clinical methods for monitoring response to therapy. The aim of this review is to provide a current snapshot of recent developments in this rapidly evolving field.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 119-145 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract The brain changes profoundly in structure and function during development and as a result of diseases such as the dementias, schizophrenia, multiple sclerosis, and tumor growth. Strategies to measure, map, and visualize these brain changes are of immense value in basic and clinical neuroscience. Algorithms that map brain change with sufficient spatial and temporal sensitivity can also assess drugs that aim to decelerate or arrest these changes. In neuroscience studies, these tools can reveal subtle brain changes in adolescence and old age and link these changes with measurable differences in brain function and cognition. Early detection of brain change in patients at risk for dementia; tumor recurrence; or relapsing-remitting conditions, such as multiple sclerosis, is also vital for optimizing therapy. We review a variety of mathematical and computational approaches to detect structural brain change with unprecedented sensitivity, both spatially and temporally. The resulting four-dimensional (4-D) maps of brain anatomy are warehoused in population-based brain atlases. Here, statistical tools compare brain changes across subjects and across populations, adjusting for complex differences in brain structure. Brain changes in an individual can be compared with a normative database comprised of subjects matched for age, gender, and other demographic factors. These dynamic brain maps offer key biological markers for understanding disease progression and testing therapeutic response. The early detection of disease-related brain changes is also critical for possible pre-emptive intervention before the ravages of disease have set in.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 207-249 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract The history of cochlear implants is marked by large improvements in performance, especially over the past two decades and especially due to the development of ever-better processing strategies. Although the progress to date has been substantial, present devices still do not restore normal speech reception, even for top performers and particularly for listening to speech in competition with noise or other talkers. In addition, a wide range of outcomes persists, with some patients receiving little benefit using the same devices that support high levels of speech reception for others. The purpose of this review is to describe some likely possibilities for further improvement, including (a) combined electric and acoustic stimulation of the auditory system for patients with significant residual hearing, (b) use of bilateral implants, (c) a closer replication with implants of the processing steps in the normal cochlea, and (d) applications of knowledge about factors that are correlated with outcomes to help patients presently at the low end of the performance scale.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 293-347 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Nerve regeneration is a complex biological phenomenon. In the peripheral nervous system, nerves can regenerate on their own if injuries are small. Larger injuries must be surgically treated, typically with nerve grafts harvested from elsewhere in the body. Spinal cord injury is more complicated, as there are factors in the body that inhibit repair. Unfortunately, a solution to completely repair spinal cord injury has not been found. Thus, bioengineering strategies for the peripheral nervous system are focused on alternatives to the nerve graft, whereas efforts for spinal cord injury are focused on creating a permissive environment for regeneration. Fortunately, recent advances in neuroscience, cell culture, genetic techniques, and biomaterials provide optimism for new treatments for nerve injuries. This article reviews the nervous system physiology, the factors that are critical for nerve repair, and the current approaches that are being explored to aid peripheral nerve regeneration and spinal cord repair.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 79-118 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Atherosclerosis is a disease of the large arteries that involves a characteristic accumulation of high-molecular-weight lipoprotein in the arterial wall. This review focuses on the mass transport processes that mediate the focal accumulation of lipid in arteries and places particular emphasis on the role of fluid mechanical forces in modulating mass transport phenomena. In the final analysis, four mass transport mechanisms emerge that may be important in the localization of atherosclerosis: blood phase controlled hypoxia, leaky endothelial junctions, transient intercellular junction remodeling, and convective clearance of the subendothelial intima and media. Further study of these mechanisms may contribute to the development of therapeutic strategies for atherosclerotic diseases.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 57-78 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract For millennia, physicians have used palpation as a part of the physical examination to detect pathology. The ubiquitous presence of "stiffer" tissue associated with pathology often represents an early warning sign for disease, as in the cases of breast or prostate cancer. Very often tumors are found at surgery that were occult even with modern imaging instruments. This implies that methods for estimating "hardness" of tissues would add a weapon to the medical armamentarium. To this end, this review discusses several methods of estimating tissue hardness using internal or external means of applying stress (force per unit area) and several associated methods of detecting the resulting strain (fractional length change) in an effort to image a tissue mechanical property, such as Young's modulus (ratio of stress to strain). Some investigators have developed methods of estimating stiffness or modulus, but most methods result in qualitative images of stiffness. Nevertheless, such estimates may add a great deal of information not currently available to the current field of medical imaging.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 179-206 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract The rapid accumulation of genetic information and advancement of experimental techniques have opened a new frontier in biomedical engineering. With the availability of well-characterized components from natural gene networks, the stage has been set for the engineering of artificial gene regulatory networks with sophisticated computational and functional capabilities. In these efforts, the ability to construct, analyze, and interpret qualitative and quantitative models is becoming increasingly important. In this review, we consider the current state of gene network engineering from a combined experimental and modeling perspective. We discuss how networks with increased complexity are being constructed from simple modular components and how quantitative deterministic and stochastic modeling of these modules may provide the foundation for accurate in silico representations of gene regulatory network function in vivo.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 285-292 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Advances in chemistry and physics are providing an expanding array of nanostructured materials with unique and powerful optical properties. These nanomaterials provide a new set of tools that are available to biomedical engineers, biologists, and medical scientists who seek new tools as biosensors and probes of biological fluids, cells, and tissue chemistry and function. Nanomaterials are also being used to develop optically controlled devices for applications such as modulated drug delivery as well as optical therapeutics. This review discusses applications that have been successfully demonstrated using nanomaterials including semiconductor nanocrystals, gold nanoparticles, gold nanoshells, and silver plasmon resonant particles.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 383-412 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Wireless biomonitoring, first used in human beings for fetal heart-rate monitoring more than 30 years ago, has now become a technology for remote sensing of patients' activity, blood pulse pressure, oxygen saturation, internal pressures, orthopedic device loading, and gastrointestinal endoscopy. Technical advances in miniaturization and wireless communications have enabled development of monitoring devices that can be made available for general use by individuals/patients and caregivers. New methods for short-range wireless communications not encumbered by radio spectrum restrictions (e.g., ultra-wideband) will enable applications of wireless monitoring without interference in ambulatory subjects, in home care, and in hospitals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 29-56 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Magnetic resonance imaging (MRI) is widely applied for functional imaging of the microcirculation and for functional and structural studies of the microvasculature. The interest in the capabilities of MRI in noninvasively monitoring changes in vascular structure and function expanded over the past years, with specific efforts directed toward the development of novel imaging methods for quantification of angiogenesis. Molecular imaging approaches hold promise for further expansion of the ability to characterize the microvasculature. Exciting applications for MRI are emerging in the study of the biology of microvessels and in the evaluation of potential pharmaceutical modulators of vascular function and development, and preclinical MRI tools can serve for the design of mechanism-of-action-based noninvasive clinical methods for monitoring response to therapy. The aim of this review is to provide a current snapshot of recent developments in this rapidly evolving field.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 147-177 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Computational models of the electrical and mechanical function of the heart are reviewed. These models attempt to explain the integrated function of the heart in terms of ventricular anatomy, the structure and material properties of myocardial tissue, the membrane ion channels, and calcium handling and myofilament mechanics of cardiac myocytes. The models have established the computational framework for linking the structure and function of cardiac cells and tissue to the integrated behavior of the intact heart, but many more aspects of physiological function, including metabolic and signal transduction pathways, need to be included before significant progress can be made in understanding many disease processes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 251-284 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: For native and engineered biological tissues, there exist many physiological, surgical, and medical device applications where multiaxial material characterization and modeling is required. Because biological tissues and many biocompatible elastomers are incompressible, planar biaxial testing allows for a two-dimensional (2-D) stress-state that can be used to fully characterize their three-dimensional (3-D) mechanical properties. Biological tissues exhibit complex mechanical behaviors not easily accounted for in classic elastomeric constitutive models. Accounting for these behaviors by careful experimental evaluation and formulation of constitutive models continues to be a challenging area in biomechanical modeling and simulation. The focus of this review is to describe the application of multiaxial testing techniques to soft tissues and their relation to modern biomechanical constitutive theories.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 293-347 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Nerve regeneration is a complex biological phenomenon. In the peripheral nervous system, nerves can regenerate on their own if injuries are small. Larger injuries must be surgically treated, typically with nerve grafts harvested from elsewhere in the body. Spinal cord injury is more complicated, as there are factors in the body that inhibit repair. Unfortunately, a solution to completely repair spinal cord injury has not been found. Thus, bioengineering strategies for the peripheral nervous system are focused on alternatives to the nerve graft, whereas efforts for spinal cord injury are focused on creating a permissive environment for regeneration. Fortunately, recent advances in neuroscience, cell culture, genetic techniques, and biomaterials provide optimism for new treatments for nerve injuries. This article reviews the nervous system physiology, the factors that are critical for nerve repair, and the current approaches that are being explored to aid peripheral nerve regeneration and spinal cord repair.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 5 (2003), S. 413-439 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Knowledge of blood vessel mechanical properties is fundamental to the understanding of vascular function in health and disease. Analytic results can help physicians in the clinic, both in designing and in choosing appropriate therapies. Understanding the mechanical response of blood vessels to physiologic loads is necessary before ideal therapeutic solutions can be realized. For this reason, blood vessel constitutive models are needed. This article provides a critical review of recent blood vessel constitutive models, starting with a brief overview of the structure and function of arteries and veins, followed by a discussion of experimental techniques used in the characterization of material properties. Current models are classified by type, including pseudoelastic, randomly elastic, poroelastic, and viscoelastic. Comparisons are presented between the various models and existing experimental data. Applications of blood vessel constitutive models are also briefly presented, followed by the identification of future directions in research.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 103-131 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Acid secretion by the gastric parietal cell is regulated by paracrine, endocrine, and neural pathways. The physiological stimuli include histamine, acetylcholine, and gastrin via their receptors located on the basolateral plasma membranes. Stimulation of acid secretion typically involves an initial elevation of intracellular calcium and/or cAMP followed by activation of a cAMP-dependent protein kinase cascade that triggers the translocation and insertion of the proton pump enzyme, H,K-ATPase, into the apical plasma membrane of parietal cells. Whereas the H,K-ATPase contains a plasma membrane targeting motif, the stimulation-mediated relocation of the H,K-ATPase from the cytoplasmic membrane compartment to the apical plasma membrane is mediated by a SNARE protein complex and its regulatory proteins. This review summarizes the progress made toward an understanding of the cell biology of gastric acid secretion. In particular we have reviewed the early signaling events following histaminergic and cholinergic activation, the identification of multiple factors participating in the trafficking and recycling of the proton pump, and the role of the cytoskeleton in supporting the apical pole remodeling, which appears to be necessary for active acid secretion by the parietal cell. Emphasis is placed on identifying protein factors that serve as effectors for the mechanistic changes associated with cellular activation and the secretory response.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 203-230 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Comparative physiology has proven a powerful approach to our understanding of how animals function under hypoxic conditions and to identifying potential adaptations to environmental oxygen levels. This review considers the potential for using a similar comparative approach with functional genomics to understand the genetic basis of such physiological processes and evolutionary adaptations. Comparative functional genomics is currently limited by genome data, which are available for only a few model organisms. However, comparative studies between model organisms of the same species having slightly different genomes (e.g., in-bred strains of laboratory rodents, transgenic mice, and consomic rats) demonstrate the types of results, as well as the analytical challenges, that are possible if comparative functional genomics is applied to more species. Results from wild and domestic animal studies suggest new models to investigate physiological and evolutionary responses to oxygen levels with functional genomics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 531-542 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract The physiological tuning and pathophysiological alterations of renal proximal reabsorption of inorganic phosphate can be ascribed to the net amount of the Na/Pi-cotransporter NaPi-IIa localized in the brush border membrane. The net amount of NaPi-IIa appears to be the result of an endocytotic rate regulated by a complex network of different protein kinases. New approaches demonstrated that NaPi-IIa is part of heteromeric protein complexes, organized by PDZ (postsynaptic protein PSD95, Drosophila junction protein Disc-large, tight junction protein ZO-1) proteins. Such complexes are thought to play important roles in the apical positioning and regulated endocytosis of NaPi-IIa and therefore such interactions have to be considered when explaining proximal phosphate ion reabsorption.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 65 (2003), S. 669-695 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Understanding of the functions and regulation of the phenotype of the alveolar type I epithelial cell has lagged behind studies of its neighbor the type II cell because of lack of cell-specific molecular markers. The recent identification of several proteins expressed by type I cells indicates that these cells may play important roles in regulation of cell proliferation, ion transport and water flow, metabolism of peptides, modulation of macrophage functions, and signaling events in the peripheral lung. Cell systems and reagents are available to characterize type I cell biology in detail, an important goal given that the cells provide the extensive surface that facilitates gas exchange in the intact animal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...