ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Soil and Vegetation in British Somaliland (1950)
    [s.l.] : Nature Publishing Group
    Nature 165 (1950), S. 901-901 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] There is conclusive evidence that the soils of British Somaliland are in the process of severe erosion as a consequence of drastic overgrazing and cutting of branches of a great number of species of trees as fodder when herbaceous pastorage has become de-pleted. Extensive forests of dead trees are ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/165901a0
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Mutagenicity of 2-amino-N^6-hydroxyadenine (AHA) at three loci in L5178Y/tk^+/- mouse lymphoma cells: molecular and preliminary cytogenetic characterizations of AHA-induced tk^-^/^- mutants
    Amsterdam : Elsevier
    Mutation Research/Environmental Mutagenesis and Related Subjects 253 (1991), S. 73-82 
    Details
    ISSN: 0165-1161
    Keywords: Allele loss ; Chromosome aberrations ; Fischer's medium ; L5178Y cells ; Large colony mutants ; Macromutations ; Mouse lymphoma assay ; Point mutations ; Recombination ; Small colony mutants ; Thymidine kinase locus
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0165-1161(91)90347-B
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    α/β phase transition in quartz monitored using acoustic emissions (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 120 (1995), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: It is usually suggested that thermal cracking in a quartz-bearing rock results from the anomalously high volumetric expansion coefficients of quartz (e.g. Simmons & Cooper 1978). It has also been recognized that thermal expansion mismatch and mineral anisotropy contribute to thermal cracking in materials that consist of a polycrystalline aggregate composed of several anisotropic minerals even in the absence of a temperature gradient (Friedrich & Wong 1986). Experiments investigating thermal cracking in rocks commonly involve imaging and quantitative stereology of crack populations induced in rocks treated to various peak temperatures (e.g. Friedrich & Johnson 1978; Homand-Etienne & Troalan 1984; Atkinson, McDonald & Meredith 1984; Meredith & Atkinson 1985). Here we report on acoustic-emission experiments that monitor the process of thermal cracking as it occurs during heating, supported by measurements of crack surface area, pore-fluid permeability, porosity and surface conductivity carried out on rock samples treated to various peak temperatures. The acoustic-emission measurements show a strong peak of microcracking at the phase transition temperature for quartz (˜573°C) superimposed upon a background of microcracking due to thermal expansion. There is also a clear peak of microcracking at higher temperatures (˜800°C) that can be attributed to oxidation-dehydroxylation reactions of hornblende and chlorite. Measurements of fluid permeability, pore surface area, porosity and electrical conductivity, made on samples that have been heat treated to various maximum temperatures, show increases associated with a major episode of cracking in the 500-600°C temperature range, indicating that the new cracks form a well-interconnected network. This has been confirmed by SEM and optical microscopy These results have implications for the electrical conductivity of the continental crust, providing a mechanism enabling the high pore-fluid connectivity needed to explain zones of high electrical conductivity at depth providing that cracks opened in this way remain open at the high pressures existing at depth. It should be recognized, however, that th***se measurements are limited in their direct application since they were obtained under initially dry conditions at laboratory pressures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1995.tb01852.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Snap-shot magnetic resonance imaging at 0.1 T using double-screened gradients
    Amsterdam : Elsevier
    Journal of Magnetic Resonance (1969) 80 (1988), S. 248-258 
    Details
    ISSN: 0022-2364
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0022-2364(88)90294-6
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Multiple spin echoes in liquids in a high magnetic field
    Amsterdam : Elsevier
    Journal of Magnetic Resonance (1969) 88 (1990), S. 643-651 
    Details
    ISSN: 0022-2364
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0022-2364(90)90297-M
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Ten Years’Operational Experience with an Activated-Sludge Plant in a Gulf State (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 7 (1993), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The particular difficulties of sewage treatment in a Gulf State of the Middle East are highlighted. Ambient temperatures may at times exceed 50°C, and sand and dust can be a problem. A description is given of the sewerage and sewage-treatment facilities at Al Ain in the United Arab Emirates, together with analytical data and flow records from commissioning until 1991. Attention is drawn to the problem of rapid anaerobic decomposition of sewage, consequent septicity, emission of foul odours, and hazardous hydrogen sulphide. There is a need for better control of this nuisance. Comment is made on high temperatures, and also on loss by latent heat of evaporation. The inability to reconcile sludge production with that indicated by empirical data, or predicted by sludge production formulae, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1993.tb00858.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Modelling the stress-strain behaviour of saturated rocks undergoing triaxial deformation using complex electrical conductivity measurements (1996)
    Springer
    Surveys in geophysics 17 (1996), S. 307-330 
    Details
    ISSN: 1573-0956
    Keywords: Complex electrical conductivity ; Stress-strain modelling ; Cracked solids ; Triaxial deformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Measurement of complex electrical conductivity as a function of frequency is an extremely sensitive probe for changes in pore and crack volume, crack connectivity, and crack surface topography. Such measurements have been made as a function of pore fluid chemistry, hydrostatic confining pressure, as well as uniaxial and triaxial deformation. This paper will; (1) describe the effects of triaxial deformation on the complex electrical conductivity of saturated porous rocks, (2) use the electrical data to model the mechanical stress-strain behaviour, and (3) compare the modelled behaviour with the stress-strain behaviour measured during the deformation. Experimental conductivity data tracks how the rock undergoes compaction with progressive loss of crack volume, followed by dilatation due to new crack formation, growth of existing cracks, crack interlinkage, and finally failure, as axial strain is increased. We have used the complex electrical data to produce a direction-sensitive (anisotropic) crack damage parameter, and used it to calculate the effective Young's modulus by employing the models of Walsh and Bruner. Comparison of the synthetic stress-strain curves so produced, with the experimentally derived stress-strain curves shows good agreement, particularly for undrained tests. This modelling is an improvement on similar curves produced using isotropic crack damage parameters derived from acoustic emission data. The improvement is likely to be due to the directional sensitivity of the electrical conductivity measurement, and its ability to discriminate between the formation of isolated cracks, and those cracks that contribute to the inter-connected crack space i.e. those cracks upon which transport properties of the rock such as electrical conductivity, and mechanical properties depend most critically during triaxial deformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01904046
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    High-resolution echo-planar imaging at 3.0 T (1994)
    Springer
    Magnetic resonance materials in physics, biology and medicine 2 (1994), S. 241-245 
    Details
    ISSN: 1352-8661
    Keywords: echo-planar imaging ; high magnetic field ; image distortion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics
    Notes: Abstract Echo-planar imaging (EPI) is a snapshot technique, which is useful in a wide range of clinical applications, including the study of physiological function. Over recent years, EPI has found a major new use in functional imaging of the brain. Many EPI experiments can benefit from the increased signal-to-noise ratio (S/N) which results from imaging at high magnetic field. Recently, we have built a 3.0-T EPI scanner at Nottingham University. The low-level radiofrequency and control electronics have been constructed in-house. This, coupled with software written specifically for the system, results in a performance and flexibility exceeding that of a commercial system. A quiet head gradient set produces gradients of up to 30 mT m−1. It is driven using a series multiresonant filter circuit, which allows the production of high-strength, trapezoidal- or sinusoidal-switched gradients. Using this scanner it has been possible to obtain images comprising 256×256 pixels, with a 2.5-mm slice and 0.75 mm in-plane resolution, in 140 ms. Multislicing allows a volume set of 16,128×128 images to be obtained in 1.6 s. A comparison of tests performed at fields of 0.5 T and 3.0 T on the same phantom indicates a better than linear increase in S/N with field strength. EPI images obtained at 3.0 T have been used in studies of brain activation during visual stimulation and execution of a simple motor task.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01705247
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Functional brain imaging using EPI at 3 T (1994)
    Springer
    Magnetic resonance materials in physics, biology and medicine 2 (1994), S. 347-349 
    Details
    ISSN: 1352-8661
    Keywords: functional imaging ; EPI ; brain transfer function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics
    Notes: Abstract Functional magnetic resonance imaging (fMRI) is becoming an important tool in the mapping of brain activation. However there are two main concerns that need to be answered before functional imaging can be considered truly useful as a neurophysiological tool. The first is that the detected activation may be derived from large veins and, thus, be spatially separate from the underlying brain activity. The second is the incomplete understanding of the brain transfer function and its relation to brain activity, blood flow, and metabolism. This work contains initial results that will help address these points. Models of the brain vasculature predict that signal changes on SE (spin-echo) images are expected to be much smaller in magnitude but very accurate in localizing true areas of activation than on GE (gradient-echo) images which are susceptable to large veins. By comparing activation from SE and GE EPI at 3 T, we have shown that the regions of activation are spatially very similar, suggesting that GE activation is closely linked to the underlying brain activity. We have identified an experimental impulse response of the brain following 8-s visual stimulation. This impulse response can be used to successfully predict the frequency response obtained experimentally and its shape suggests a resonance phenomenon. This suggests the brain transfer function can be modeled from linear response theory corresponding to the inherent feedback control mechanisms of the brain homeostasis. Continuation of this early work will help to identify the links between fMRI signal change and underlying brain physiology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01705268
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Glycogen resynthesis in liver and muscle after exercise: measurement of the rate of resynthesis by13C magnetic resonance spectroscopy (1994)
    Springer
    Magnetic resonance materials in physics, biology and medicine 2 (1994), S. 429-432 
    Details
    ISSN: 1352-8661
    Keywords: Magnetic resonance spectroscopy ; glycogen ; liver ; muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics
    Notes: Abstract We have used natural abundance13C magnetic resonance spectroscopy (MRS) to measure glycogen content of muscle and liver before and after heavy exercise, and after consumption of different carbohydrate-based drinks. After an overnight fast, five healthy men (mean±SEM age 23±1 years) exercised to exhaustion at 75% of VO2max on two occasions (mean work rate 165±8 W for 78±14 min) and then, in a single blind random order, consumed either of two drinks containing the same carbohydrate load (177 g). Spectra were recorded over Vastus Lateralis muscle and the liver before and after exercise, and hourly for 5 h after the carbohydrate load. In muscle, glycogen content after exercise was 37% and 31% of basal (preexercise) concentration before consuming the drinks. After carbohydrate loading, glycogen concentration had increased significantly (p〈0.05) to 70% and 64% of basal concentration respectively after 5 h. Hepatic glycogen concentration did not change significantly throughout. The study demonstrates the feasibility of sequential MRS measurement of muscle and liver glycogen before and after exercise and after carbohydrate loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01705290
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...