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  • 1
    Publication Date: 2013-09-21
    Description: [1]  We have developed a new method (LRISMA: Least Residual Iterative Spectral Mixture Analysis) to semi-quantitatively determine major rock forming minerals (feldspar, pyroxene, olivine, high-silica phases and quartz) with multispectral thermal infrared data. Sub-libraries of minerals are generated from a master library of minerals based on prior knowledge to produce a suite of realistic mineral end-member combinations to fit the target spectra. Mineral abundances that correspond to the least root-mean-square (RMS) errors (best fit) generally agree best with previous petrographic studies of laboratory measured rock samples and thermal infrared hyperspectral analysis of materials on the surface of Mars, given the greatly reduced spectral range and resolution of Thermal Emission Imaging System (THEMIS). The accuracy and reproducibility of LRISMA is ~4-16% and ~5-20% respectively, while the accuracy of petrographic and previous hyperspectral studies is ~5-15% [ e . g. Feely and Christensen , 1999]. LRISMA can be applied to semi-quantitatively refine the bulk surface mineralogy of small-scale (~1 km 2 ) geologic features with high quality THEMIS spectral data (high surface temperature: 〉260 K, low atmospheric opacity: total ice 〈 0.04 and total dust 〈 0.15) with the ultimate goal of better understanding regional geologic processes.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
    Publication Date: 2012-03-07
    Description: Transcription regulation by steroid hormones, vitamin derivatives, and metabolites is mediated by nuclear receptors (NRs), which play an important role in ligand-dependent gene expression and human health. NRs function as homodimers or heterodimers and are involved in a combinatorial, coordinated and sequentially orchestrated exchange between coregulators (corepressors, coactivators). The architecture of DNA-bound functional dimers positions the coregulators proteins. We previously demonstrated that retinoic acid (RAR-RXR) and vitamin D3 receptors (VDR-RXR) heterodimers recruit only one coactivator molecule asymmetrically without steric hindrance for the binding of a second cofactor. We now address the problem of homodimers for which the presence of two identical targets enhances the functional importance of the mode of binding. Using structural and biophysical methods and RAR as a model, we could dissect the molecular mechanism of coactivator recruitment to homodimers. Our study reveals an allosteric mechanism whereby binding of a coactivator promotes formation of nonsymmetrical RAR homodimers with a 2∶1 stoichiometry. Ligand conformation and the cofactor binding site of the unbound receptor are affected through the dimer interface. A similar control mechanism is observed with estrogen receptor (ER) thus validating the negative cooperativity model for an established functional homodimer. Correlation with published data on other NRs confirms the general character of this regulatory pathway.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 3
    Publication Date: 2011-07-07
    Description: Chemical, mineralogic, and lithologic ground truth was acquired for the first time on Mars in terrain units mapped using orbital Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (MRO HiRISE) image data. Examination of several dozen outcrops shows that Mars is geologically complex at meter length scales, the record of its geologic history is well exposed, stratigraphic units may be identified and correlated across significant areas on the ground, and outcrops and geologic relationships between materials may be analyzed with techniques commonly employed in terrestrial field geology. Despite their burial during the course of Martian geologic time by widespread epiclastic materials, mobile fines, and fall deposits, the selective exhumation of deep and well-preserved geologic units has exposed undisturbed outcrops, stratigraphic sections, and structural information much as they are preserved and exposed on Earth. A rich geologic record awaits skilled future field investigators on Mars. The correlation of ground observations and orbital images enables construction of a corresponding geologic reconnaissance map. Most of the outcrops visited are interpreted to be pyroclastic, impactite, and epiclastic deposits overlying an unexposed substrate, probably related to a modified Gusev crater central peak. Fluids have altered chemistry and mineralogy of these protoliths in degrees that vary substantially within the same map unit. Examination of the rocks exposed above and below the major unconformity between the plains lavas and the Columbia Hills directly confirms the general conclusion from remote sensing in previous studies over past years that the early history of Mars was a time of more intense deposition and modification of the surface. Although the availability of fluids and the chemical and mineral activity declined from this early period, significant later volcanism and fluid convection enabled additional, if localized, chemical activity.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Publication Date: 2007-05-05
    Description: Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarsegrained lower unit lies under a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic origin over an impact origin. The lower unit likely represents accumulation of pyroclastic materials, whereas the upper unit may represent eolian reworking of the same pyroclastic materials.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Squyres, S W -- Aharonson, O -- Clark, B C -- Cohen, B A -- Crumpler, L -- de Souza, P A -- Farrand, W H -- Gellert, R -- Grant, J -- Grotzinger, J P -- Haldemann, A F C -- Johnson, J R -- Klingelhofer, G -- Lewis, K W -- Li, R -- McCoy, T -- McEwen, A S -- McSween, H Y -- Ming, D W -- Moore, J M -- Morris, R V -- Parker, T J -- Rice, J W Jr -- Ruff, S -- Schmidt, M -- Schroder, C -- Soderblom, L A -- Yen, A -- New York, N.Y. -- Science. 2007 May 4;316(5825):738-42.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17478719" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2008-05-24
    Description: Mineral deposits on the martian surface can elucidate ancient environmental conditions on the planet. Opaline silica deposits (as much as 91 weight percent SiO2) have been found in association with volcanic materials by the Mars rover Spirit. The deposits are present both as light-toned soils and as bedrock. We interpret these materials to have formed under hydrothermal conditions and therefore to be strong indicators of a former aqueous environment. This discovery is important for understanding the past habitability of Mars because hydrothermal environments on Earth support thriving microbial ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Squyres, S W -- Arvidson, R E -- Ruff, S -- Gellert, R -- Morris, R V -- Ming, D W -- Crumpler, L -- Farmer, J D -- Marais, D J Des -- Yen, A -- McLennan, S M -- Calvin, W -- Bell, J F 3rd -- Clark, B C -- Wang, A -- McCoy, T J -- Schmidt, M E -- de Souza, P A Jr -- New York, N.Y. -- Science. 2008 May 23;320(5879):1063-7. doi: 10.1126/science.1155429.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA. squyres@astro.cornell.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18497295" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Hot Temperature ; Hydrogen-Ion Concentration ; *Mars ; *Silicon Dioxide ; Spacecraft ; *Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2004-08-07
    Description: Wind-abraded rocks, ripples, drifts, and other deposits of windblown sediments are seen at the Columbia Memorial Station where the Spirit rover landed. Orientations of these features suggest formative winds from the north-northwest, consistent with predictions from atmospheric models of afternoon winds in Gusev Crater. Cuttings from the rover Rock Abrasion Tool are asymmetrically distributed toward the south-southeast, suggesting active winds from the north-northwest at the time (midday) of the abrasion operations. Characteristics of some rocks, such as a two-toned appearance, suggest that they were possibly buried and exhumed on the order of 5 to 60 centimeters by wind deflation, depending on location.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Greeley, R -- Squyres, S W -- Arvidson, R E -- Bartlett, P -- Bell, J F 3rd -- Blaney, D -- Cabrol, N A -- Farmer, J -- Farrand, B -- Golombek, M P -- Gorevan, S P -- Grant, J A -- Haldemann, A F C -- Herkenhoff, K E -- Johnson, J -- Landis, G -- Madsen, M B -- McLennan, S M -- Moersch, J -- Rice, J W Jr -- Richter, L -- Ruff, S -- Sullivan, R J -- Thompson, S D -- Wang, A -- Weitz, C M -- Whelley, P -- New York, N.Y. -- Science. 2004 Aug 6;305(5685):810-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geological Sciences, Arizona State University, Box 871404, Tempe, AZ 85287-1404, USA. Greeley@asu.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15297660" target="_blank"〉PubMed〈/a〉
    Keywords: Evolution, Planetary ; Extraterrestrial Environment ; *Mars ; Wind
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2004-08-07
    Description: The Mars Exploration Rover Spirit has traversed a fairly flat, rock-strewn terrain whose surface is shaped primarily by impact events, although some of the landscape has been altered by eolian processes. Impacts ejected basaltic rocks that probably were part of locally formed lava flows from at least 10 meters depth. Some rocks have been textured and/or partially buried by windblown sediments less than 2 millimeters in diameter that concentrate within shallow, partially filled, circular impact depressions referred to as hollows. The terrain traversed during the 90-sol (martian solar day) nominal mission shows no evidence for an ancient lake in Gusev crater.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grant, J A -- Arvidson, R -- Bell, J F 3rd -- Cabrol, N A -- Carr, M H -- Christensen, P -- Crumpler, L -- Des Marais, D J -- Ehlmann, B L -- Farmer, J -- Golombek, M -- Grant, F D -- Greeley, R -- Herkenhoff, K -- Li, R -- McSween, H Y -- Ming, D W -- Moersch, J -- Rice, J W Jr -- Ruff, S -- Richter, L -- Squyres, S -- Sullivan, R -- Weitz, C -- New York, N.Y. -- Science. 2004 Aug 6;305(5685):807-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20560, USA. grantj@nasm.si.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15297659" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Geologic Sediments ; *Mars ; Minerals ; Silicates ; Volcanic Eruptions ; Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 1993-09-24
    Description: Intraperitoneal injection of epidermal growth factor (EGF) into mice resulted in the appearance in liver nuclei of three tyrosine phosphorylated proteins (84, 91, and 92 kilodaltons) within minutes after administration of EGF. Administration of interferon-gamma (IFN-gamma) resulted in the appearance in liver nuclei of two tyrosine phosphorylated proteins (84 and 91 kilodaltons). The 84- and 91-kilodalton proteins detected after either EGF or IFN-gamma administration were identified as the IFN-gamma activation factors (GAF). Furthermore, gel shift analysis revealed that these GAF proteins, detected after either EGF or IFN-gamma administration, specifically bound to the sis-inducible element of the c-fos promoter. Thus, GAF proteins participate in nuclear signaling in both IFN-gamma and EGF pathways.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ruff-Jamison, S -- Chen, K -- Cohen, S -- HD-00700/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 1993 Sep 24;261(5129):1733-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8378774" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cell Nucleus/drug effects/*metabolism ; DNA-Binding Proteins/*metabolism ; Epidermal Growth Factor/*pharmacology ; Genes, fos ; Interferon-Stimulated Gene Factor 3 ; Interferon-gamma/*pharmacology ; Liver/drug effects/metabolism ; Mice ; Molecular Sequence Data ; Phosphorylation ; Promoter Regions, Genetic ; STAT1 Transcription Factor ; *Trans-Activators ; Transcription Factors/*metabolism ; Tyrosine/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2013-08-15
    Description: Article Animal experiments to study the detrimental health effects of sugar usually involve far higher doses than those consumed by humans. Here, Ruff et al. show that house mice consuming comparatively low amounts of added sugar are impaired in their ability to compete for territories, reproduce and survive in a seminatural environment. Nature Communications doi: 10.1038/ncomms3245 Authors: James S. Ruff, Amanda K. Suchy, Sara A. Hugentobler, Mirtha M. Sosa, Bradley L. Schwartz, Linda C. Morrison, Sin H. Gieng, Mark K. Shigenaga, Wayne K. Potts
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 10
    Publication Date: 2017-01-28
    Description: Sexual size dimorphism results when female and male body size is influenced differently by natural and sexual selection. Typically, in polygynous species larger male body size is thought to be favored in competition for mates and constraints on maximal body size are due to countervailing natural selection on either sex; however, it has been postulated that sexual selection itself may result in stabilizing selection at an optimal mass. Here we test this hypothesis by retrospectively assessing the influence of body mass, one metric of body size, on the fitness of 113 wild-derived house mice (Mus musculus ) residing within ten replicate semi-natural enclosures from previous studies conducted by our laboratory. Enclosures possess similar levels of sexual selection, but relaxed natural selection, relative to natural systems. Heavier females produced more offspring, while males of intermediate mass had the highest fitness. Female results suggest that some aspect of natural selection, absent from enclosures, acts to decrease their body mass, while the upper and lower boundaries of male mass are constrained by sexual selection. In polygynous species, larger male body size is thought to be favored in competition for mates and constraints on maximal body size are due to natural selection; however, it has been postulated that sexual selection itself may result in stabilizing selection on body size. Here we test this hypothesis by assessing the influence of body mass on the fitness of house mice ( Mus musculus ) residing within semi-natural enclosures. Heavier females produced more offspring, while males of intermediate mass had the highest fitness.
    Electronic ISSN: 2045-7758
    Topics: Biology
    Published by Wiley
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