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  • 1
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    Radiocarbon dating of glacial dust layers and soils at Kilimanjaro's Northern Ice Field (2014)
    Sage
    In: Holocene
    Details
    Publication Date: 2014-09-12
    Description: As the African climate history recorded in Kilimanjaro’s Northern Ice Field (NIF) is rapidly lost, the age of the glacier remains disputed. Current age estimates from ice core data and glacial dynamics modeling disagree by an order of magnitude (11,700 vs ~1000 years old). We present radiocarbon dates of glacial dust and proximal soil samples collected from in and around the edge of the NIF that support the hypothesis that the peripheral portions of the NIF glacier are younger and more dynamic than the center. Samples of a dust-rich ice layer, 1.5 m above the base at the edge of the ~40 m high glacier ice cliff were found to be 1600–790 years old. These dates agree with the prediction of significant growth and shrinkage in glacial coverage over the last millennium. The variation in radiocarbon ages likely arises from heterogeneity in the summit volcanic soils, the main source of the dust recovered from the glacier, and cryoconite microbial activity. Sediment samples of a supraglacial pond had modern radiocarbon ages, further demonstrating the impact of cryoconite microbial communities on radiocarbon measurements of glacial samples. After accounting for the variability in the sample ages and the effects of microbial activity, we contend that the lower (i.e. younger) limit of the radiocarbon age range is the most reliable assessment of the age of the ice in which it was trapped.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 2
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    Insulin staining of ES cell progeny from insulin uptake (2003)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2003-01-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rajagopal, Jayaraj -- Anderson, William J -- Kume, Shoen -- Martinez, Olga I -- Melton, Douglas A -- New York, N.Y. -- Science. 2003 Jan 17;299(5605):363.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12532008" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies/immunology ; Apoptosis ; Cell Differentiation ; Cell Line ; Embryo, Mammalian/*cytology ; Humans ; Insulin/*analysis/genetics/immunology/*metabolism ; Islets of Langerhans/*cytology/metabolism ; Mice ; Microscopy, Confocal ; RNA, Messenger/genetics/metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Stem Cells/*cytology/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
    Electronic Resource
    Electronic Resource
    Generalizations of reaction rate integrals with applications to nuclear synthesis in astrophysics and some corrections to published literature (1993)
    Springer
    Astrophysics and space science 203 (1993), S. 43-52 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Under the Maxwell-Boltzmann approach, the study of nuclear reactions in dense astrophysical plasmas under various cases (such as resonant, non-resonant, modified non-resonant, non-resonant under electron screening, and so on) leads to a class of complicated reaction rate integrals. It is shown that this general class of integrals can be identified with an integral involving the product of twoH-functions. This latter integral is evaluated in this article, and following Buschman (1979), several similar results in the published literature are shown to be incorrect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659413
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Astrophysical thermonuclear functions (1994)
    Springer
    Astrophysics and space science 214 (1994), S. 49-70 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Stars are gravitationally stabilized fusion reactors changing their chemical composition while transforming light atomic nuclei into heavy ones. The atomic nuclei are supposed to be in thermal equilibrium with the ambient plasma. The majority of reactions among nuclei leading to a nuclear transformation are inhibited by the necessity for the charged participants to tunnel through their mutual Coulomb barrier. As theoretical knowledge and experimental verification of nuclear cross sections increases it becomes possible to refine analytic representations for nuclear reaction rates. Over the years various approaches have been made to derive closed-form representations of thermonuclear reaction rates (Critchfield, 1972; Haubold and John, 1978; Haubold, Mathai and Anderson, 1987). They show that the reaction rate contains the astrophysical cross section factor and its derivatives which has to be determined experimentally, and an integral part of the thermonuclear reaction rate independent from experimental results which can be treated by closed-form representation techniques in terms of generalized hypergeometric functions. In this paper mathematical/statistical techniques for deriving closed-form representations of thermonuclear functions, particularly the four integrals $$\begin{gathered} I_1 (z,v)\mathop = \limits^{def} \int\limits_0^\infty {y^v e^{ - y} e^{ - zy^{ - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} } dy,} \hfill \\ I_2 (z,d,v)\mathop = \limits^{def} \int\limits_0^\infty {y^v e^{ - y} e^{ - zy^{ - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} } dy,} \hfill \\ I_3 (z,t,v)\mathop = \limits^{def} \int\limits_0^\infty {y^v e^{ - y} e^{ - z(y + 1)^{ - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} } dy,} \hfill \\ I_4 (z,\delta ,b,v)\mathop = \limits^{def} \int\limits_0^\infty {y^v e^{ - y} e^{ - by^\delta } e^{ - zy^{ - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} } dy,} \hfill \\ \end{gathered} $$ will be summarized and numerical results for them will be given. The separation of thermonuclear functions from thermonuclear reaction rates is our preferred result. The purpose of the paper is also to compare numerical results for approximate and closed-form representations of thermonuclear functions. This paper completes the work of Haubold, Mathai, and Anderson (1987).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00982324
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  • 5
    Electronic Resource
    Electronic Resource
    An experimental study of stress singularities at a sharp corner in a contact problem (1990)
    Springer
    Experimental mechanics 30 (1990), S. 281-285 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The photoelastic method was used to investigate the nature of the local stress field at a sharp corner of a wedge that was compressed against a larger body. Planar wedge specimens made of photoelastic material were compressed against a half plane (larger body) of identical material at various load levels. Several wedge angles were studied. The nature of the singular stress field postulated by linear elastic analysis was verified and the strength of the singularity was obtained by plotting the variation of fringe order as a function of radial distance from the sharp corner on a logarithmic scale. The experimental results were found to be in good agreement with the theoretical predictions. The effect of interface friction and the effect of rounding off the sharp edge are brietly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02322823
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  • 6
    Electronic Resource
    Electronic Resource
    An electromagnetic forcing device (1978)
    Springer
    Experimental mechanics 18 (1978), S. 161-166 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The paper describes the drawbacks of an electromagnetic forcing device, of the type commonly used to study forced vibration of structures, and presents details of a feedback control system designed to overcome them. The work described was initiated when attempting to generate sinusoidal forcing in a nonlinear beam-vibration study. Magnetic-material nonlinearities and spatial inhomogenieties in the magnetic field led to unwanted harmonics in the force the beam experienced, and feedback was used to reduce these effects. A brief description of the principles of feedback control is presented and the problems encountered in applying the concepts to the electromagnetic forcing device are discussed. Details of the system, its problems, operating characteristics and limitations are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02324136
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  • 7
    Electronic Resource
    Electronic Resource
    Reduction of contact stress by use of relief notches (1991)
    Springer
    Experimental mechanics 31 (1991), S. 271-275 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The photoelastic method is used to investigate the possibility of relieving the large local stresses that develop in the corners of a right angled indenter compressing a semi-infinite body by inducing geometric changes to the indenter/semi-infinite body configuration. It is shown that a circular notch cut along the free edges of the indenter can totally eliminate the large corner stresses. The notch, if placed along the interface edge of the half plane, can reduce the stress concentration, but never eliminate it. The results obtained have wide practical application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02326071
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  • 8
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    Transitive homology-guided structural studies lead to discovery of Cro proteins with 40% sequence identity but different folds (2008)
    National Academy of Sciences
    Details
    Publication Date: 2008-01-28
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 9
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    Investigation of ion‐implanted GaP layers by ellipsometry (1977)
    American Institute of Physics
    Details
    Publication Date: 1977-12-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
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  • 10
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    Force Balance at the Magnetopause Determined with MMS: Application to Flux Transfer Events (2016)
    Wiley
    Details
    Publication Date: 2016-11-19
    Description: The Magnetospheric Multiscale mission (MMS) consists of four identical spacecraft forming a closely separated (≤10 km) and nearly regular tetrahedron. This configuration enables the decoupling of spatial and temporal variations and allows the calculation of the spatial gradients of plasma and electromagnetic field quantities. We make full use of the well cross-calibrated MMS magnetometer and fast plasma instruments measurements to calculate both the magnetic and plasma forces in flux transfer events (FTEs), and evaluate the relative contributions of different forces to the magnetopause momentum variation. This analysis demonstrates that some but not all FTEs, consistent with previous studies, are indeed force-free structures in which the magnetic pressure force balances the magnetic curvature force. Furthermore, we contrast these events with FTE events that have non-force-free signatures.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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