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Institution

University of Arizona

EducationTucson, Arizona, United States
About: University of Arizona is a education organization based out in Tucson, Arizona, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 63805 authors who have published 155998 publications receiving 6854915 citations. The organization is also known as: UA & U of A.
Topics: Population, Galaxy, Star formation, Redshift, Planet


Papers
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Journal ArticleDOI
TL;DR: A revision is proposed in which the four fundamental zones are termed the ventricular, subventricular, intermediate, and marginal zones, each defined according to the form, behavior, and fate of its constituent cells.
Abstract: The layers and cells of the early developing central nervous system lack direct counterparts in the adult and must be designated by a special terminology. The inconsistent and inaccurate language now in use leads to misunderstanding and a revision is proposed in which the four fundamental zones are termed the ventricular, subventricular, intermediate, and marginal zones. Each is defined according to the form, behavior, and fate of its constituent cells. All neurons and macroglia of the central nervous system can be derived from these developmental zones.

691 citations

Journal ArticleDOI
TL;DR: Although the expression of Arc, zif268, and c-fos exhibited many similarities, Arc was most responsive to differences in behavioral task demands, and IEG RNA levels were positively correlated within a structure.
Abstract: Neuronal immediate-early gene (IEG) expression is regulated by synaptic activity and plays an important role in the neuroplastic mechanisms critical to memory consolidation. IEGs can be divided into two functional classes: (1) regulatory transcription factors (RTFs), which can broadly influence cell function depending on the "downstream" genes they regulate, and (2) "effector" proteins, which may directly modulate specific cellular functions. The objective of the current study was to determine whether the expression of an effector IEG (Arc) was similar to, or different from, that of two well characterized RTF IEGs (c-fos and zif268) after learning. IEG RNA levels from rats trained in spatial and nonspatial water tasks were determined using RNase protection assays and in situ hybridization. Overall, the regulation of the three IEGs was similar in the hippocampus and the entorhinal and primary visual cortices. Consequently, IEG RNA levels were positively correlated within a structure. By contrast, Arc and zif268 RNA levels were not correlated or only weakly correlated across structures, although c-fos RNA levels were moderately correlated across structures. Arc RNA expression differed from that of zif268 and c-fos in two regards: (1) hippocampal Arc RNA levels were correlated with learning of the hippocampal-dependent spatial, but not hippocampal-independent cued response, water task, and (2) Arc RNA levels in the hippocampus and entorhinal cortex increased after spatial reversal learning relative to an asymptotic performance group. Thus, although the expression of Arc, zif268, and c-fos exhibited many similarities, Arc was most responsive to differences in behavioral task demands.

691 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a sample of 1406 galaxy spectra at z ~ 1.4 from the DEEP2 redshift survey to show that blueshifted Mg IYI?? 2796, 2803 absorption is ubiquitous in star-forming galaxies at this epoch.
Abstract: Galactic winds are a prime suspect for the metal enrichment of the intergalactic medium (IGM) and may have a strong influence on the chemical evolution of galaxies and the nature of QSO absorption-line systems. We use a sample of 1406 galaxy spectra at z ~ 1.4 from the DEEP2 redshift survey to show that blueshifted Mg IYI ?? 2796, 2803 absorption is ubiquitous in star-forming galaxies at this epoch. This is the first detection of frequent outflowing galactic winds at z ~ 1. The presence and depth of absorption are independent of active galactic nuclei spectral signatures or galaxy morphology; major mergers are not a prerequisite for driving a galactic wind from massive galaxies. Outflows are found in co-added spectra of galaxies spanning a range of 30 times in stellar mass and 10 times in star formation rate (SFR), calibrated from K-band and from the Multiband Imaging Photometer for Spitzer IR fluxes. The outflows have column densities of order NH ~ 1020 cm-2 and characteristic velocities of ~?300-500?km?s?1, with absorption seen out to 1000?km?s?1 in the most massive, highest SFR galaxies. The velocities suggest that the outflowing gas can escape into the IGM and that massive galaxies can produce cosmologically and chemically significant outflows. Both the Mg II equivalent width and the outflow velocity are larger for galaxies of higher stellar mass and SFR, with V wind ~ SFR0.3, similar to the scaling in low redshift IR-luminous galaxies. The high frequency of outflows in the star-forming galaxy population at z ~ 1 indicates that galactic winds occur in the progenitors of massive spirals as well as those of ellipticals. The increase of outflow velocity with mass and SFR constrains theoretical models of galaxy evolution that include feedback from galactic winds, and may favor momentum-driven models for the wind physics.

691 citations

Journal ArticleDOI
TL;DR: In this paper, the spectral energy distribution templates for eleven luminous and ultraluminous purely star forming infrared galaxies and over the spectral range 0.4 μm to 30 cm were constructed.
Abstract: We show that measures of star formation rates (SFRs) for infrared galaxies using either single-band 24 μm or extinction-corrected Paα luminosities are consistent in the total infrared luminosity = L(TIR) ~ 1010 L ☉ range. MIPS 24 μm photometry can yield SFRs accurately from this luminosity upward: SFR(M ☉ yr–1) = 7.8 × 10–10 L(24 μm, L ☉) from L(TIR) = 5× 109 L ☉ to 1011 L ☉ and SFR = 7.8 × 10–10 L(24 μm, L ☉)(7.76 × 10–11 L(24))0.048 for higher L(TIR). For galaxies with L(TIR) ≥ 1010 L ☉, these new expressions should provide SFRs to within 0.2 dex. For L(TIR) ≥ 1011 L ☉, we find that the SFR of infrared galaxies is significantly underestimated using extinction-corrected Paα (and presumably using any other optical or near-infrared recombination lines). As a part of this work, we constructed spectral energy distribution templates for eleven luminous and ultraluminous purely star forming infrared galaxies and over the spectral range 0.4 μm to 30 cm. We use these templates and the SINGS data to construct average templates from 5 μm to 30 cm for infrared galaxies with L(TIR) = 5× 109 to 1013 L ☉. All of these templates are made available online.

689 citations

Journal ArticleDOI
TL;DR: Emerging knowledge of how plant nutrients respond to environmental variables and are connected to size, the effects of global change factors can be better understood.
Abstract: Biological stoichiometry theory considers the balance of multiple chemical elements in living systems, whereas metabolic scaling theory considers how size affects metabolic properties from cells to ecosystems. We review recent developments integrating biological stoichiometry and metabolic scaling theories in the context of plant ecology and global change. Although vascular plants exhibit wide variation in foliar carbon:nitrogen:phosphorus ratios, they exhibit a higher degree of 'stoichiometric homeostasis' than previously appreciated. Thus, terrestrial carbon:nitrogen:phosphorus stoichiometry will reflect the effects of adjustment to local growth conditions as well as species' replacements. Plant stoichiometry exhibits size scaling, as foliar nutrient concentration decreases with increasing plant size, especially for phosphorus. Thus, small plants have lower nitrogen:phosphorus ratios. Furthermore, foliar nutrient concentration is reflected in other tissues (root, reproductive, support), permitting the development of empirical models of production that scale from tissue to whole-plant levels. Plant stoichiometry exhibits large-scale macroecological patterns, including stronger latitudinal trends and environmental correlations for phosphorus concentration (relative to nitrogen) and a positive correlation between nutrient concentrations and geographic range size. Given this emerging knowledge of how plant nutrients respond to environmental variables and are connected to size, the effects of global change factors (such as carbon dioxide, temperature, nitrogen deposition) can be better understood.

688 citations


Authors

Showing all 64388 results

NameH-indexPapersCitations
Simon D. M. White189795231645
Julie E. Buring186950132967
David H. Weinberg183700171424
Richard Peto183683231434
Xiaohui Fan183878168522
Dennis S. Charney179802122408
Daniel J. Eisenstein179672151720
David Haussler172488224960
Carlos S. Frenk165799140345
Jian-Kang Zhu161550105551
Tobin J. Marks1591621111604
Todd Adams1541866143110
Jane A. Cauley15191499933
Wei Zheng1511929120209
Daniel L. Schacter14959290148
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023205
2022987
20217,005
20207,325
20196,716
20186,375