oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 550 )

2018 ( 734 )

2017 ( 734 )

2016 ( 1003 )

Custom range...

Search Results: 1 - 10 of 413522 matches for " William M Gray "
All listed articles are free for downloading (OA Articles)
Page 1 /413522
Display every page Item
Hormonal Regulation of Plant Growth and Development
William M. Gray
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0020311
Abstract:
Hormonal Regulation of Plant Growth and Development
William M Gray
PLOS Biology , 2004, DOI: 10.1371/journal.pbio.0020311
Abstract:
The eta7/csn3-3 Auxin Response Mutant of Arabidopsis Defines a Novel Function for the CSN3 Subunit of the COP9 Signalosome
He Huang, Marcel Quint, William M. Gray
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066578
Abstract: The COP9 signalosome (CSN) is an eight subunit protein complex conserved in all higher eukaryotes. In Arabidopsis thaliana, the CSN regulates auxin response by removing the ubiquitin-like protein NEDD8/RUB1 from the CUL1 subunit of the SCFTIR1/AFB ubiquitin-ligase (deneddylation). Previously described null mutations in any CSN subunit result in the pleiotropic cop/det/fus phenotype and cause seedling lethality, hampering the study of CSN functions in plant development. In a genetic screen to identify enhancers of the auxin response defects conferred by the tir1-1 mutation, we identified a viable csn mutant of subunit 3 (CSN3), designated eta7/csn3-3. In addition to enhancing tir1-1 mutant phenotypes, the csn3-3 mutation alone confers several phenotypes indicative of impaired auxin signaling including auxin resistant root growth and diminished auxin responsive gene expression. Unexpectedly however, csn3-3 plants are not defective in either the CSN-mediated deneddylation of CUL1 or in SCFTIR1-mediated degradation of Aux/IAA proteins. These findings suggest that csn3-3 is an atypical csn mutant that defines a novel CSN or CSN3-specific function. Consistent with this possibility, we observe dramatic differences in double mutant interactions between csn3-3 and other auxin signaling mutants compared to another weak csn mutant, csn1-10. Lastly, unlike other csn mutants, assembly of the CSN holocomplex is unaffected in csn3-3 plants. However, we detected a small CSN3-containing protein complex that is altered in csn3-3 plants. We hypothesize that in addition to its role in the CSN as a cullin deneddylase, CSN3 functions in a distinct protein complex that is required for proper auxin signaling.
Comments on "Increasing destructiveness of tropical cyclones over the past 30 years" by Kerry Emanuel, Nature, 31 July 2005, Vol. 436, pp. 686-688
William Gray
Physics , 2006,
Abstract: The near universal references to the above paper by most of the major US media outlets and blogs since Katrina and Rita made US landfall requires a response from a few of us who study hurricanes. Having been involved with hurricane research and forecasting for nearly 50 years, I feel I have an obligation to offer comments on this paper's findings which, in my view, are not valid. This paper concludes that global tropical cyclone net power dissipation (or friction times wind) taken to be proportional to the sum of each cyclone's individual 6-hour track period maximum wind speed (Vmax^3) has undergone large (more than doubled) increases over the last 30 years. The author associates these frictional energy dissipation increases with rising mean sea surface temperatures (SSTs) and implies that these SST increases may, in part, be related to human activity. If true, this is a very important finding that has great relevance as regards to the globe's future climate and future hurricane destruction. But, the author's apparent "blockbuster" results and his interpretation of his calculations are not realistic.
Comments by William M. Gray (Colorado State University) on the recently published paper in Science by Webster et al., titled "Changes in tropical cyclone number, duration, and intensity in a warming environment." (September 2005, Vol. 309, pp. 1844-1846, www.sciencemag.org)
William Gray
Physics , 2006,
Abstract: Recent US major landfalling hurricanes Katrina and Rita and last year's four U.S. landfalling major hurricanes have spawned an abundance of questions concerning the role that global warming might be playing in these events. This idea has been given added credence by the September 2005 Science paper of Webster, Holland, Curry and Chang (Vol. 304, pp. 1844-1846) showing that the global number of Category 4-5 hurricanes have increased in the last 15 years (1990-2004) in comparison with the prior 15-year period of 1975-1989. They report 171 Category 4-5 hurricanes in the earlier 15-year period vs. 269 (56% increase) in the later 15 year period. Global mean surface temperature in the later period has been about 0.3C higher than in the earlier period. The authors' imply that their measured rise in global Category 4-5 hurricanes is likely related to these higher global temperatures. Having been involved with hurricane research and forecasting for nearly 50 years, I feel I have an obligation to offer comments on this paper's primary finding on the recent rise of global Category 4-5 hurricanes. I do not agree that global Category 4-5 tropical cyclone activity has been rising, except in the Atlantic over the past 11 years. The recent Atlantic upsurge has explanations other than global temperature rise.
Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows II: Effect of Turbulence and Metal-Line Cooling
William Gray,Evan Scannapieco
Physics , 2011, DOI: 10.1088/0004-637X/733/2/88
Abstract: In the primordial universe, low mass structures with virial temperatures less than 10$^{4}$ K were unable to cool by atomic line transitions, leading to a strong suppression of star formation. On the other hand, these "minihalos" were highly prone to triggered star formation by interactions from nearby galaxy outflows. In Gray & Scannapieco (2010), we explored the impact of nonequilibrium chemistry on these interactions. Here we turn our attention to the role of metals, carrying out a series of high-resolution three-dimensional adaptive mesh refinement simulations that include both metal cooling and a subgrid turbulent mixing model. Despite the presence of an additional coolant, we again we find that outflow-minihalo interactions produce a distribution of dense, massive stellar clusters. We also find that these clusters are evenly enriched with metals to a final abundance of Z $\approx$ 10$^{-2}$ Z$_{\odot}$. As in our previous simulations, all of these properties suggest that these interactions may have given rise to present-day halo globular clusters.
An automated growth enclosure for metabolic labeling of Arabidopsis thaliana with 13C-carbon dioxide - an in vivo labeling system for proteomics and metabolomics research
Wen-Ping Chen, Xiao-Yuan Yang, Geoffrey L Harms, William M Gray, Adrian D Hegeman, Jerry D Cohen
Proteome Science , 2011, DOI: 10.1186/1477-5956-9-9
Abstract: A fully enclosed automated plant growth enclosure has been designed and assembled where the system simultaneously monitors humidity, temperature, pressure and 13CO2 concentration with continuous adjustment of humidity, pressure and 13CO2 levels controlled by a computer running LabView software. The enclosure is mounted on a movable cart for mobility among growth environments. Arabidopsis was grown in the enclosure for up to 8 weeks and obtained on average >95 atom% enrichment for small metabolites, such as amino acids and >91 atom% for large metabolites, including proteins and peptides.The capability of this labeling system for isotope dilution experiments was demonstrated by evaluation of amino acid turnover using GC-MS as well as protein turnover using LC-MS/MS. Because this 'open source' Arabidopsis 13C-labeling growth environment was built using readily available materials and software, it can be adapted easily to accommodate many different experimental designs.Radioactive and stable isotope tracing techniques have been used for decades and have yielded revolutionary insights into plant metabolism, including photorespiration [1-3] and photosynthetic carbon assimilation [4-6]. These techniques have also been utilized to study secondary plant metabolites [2,7,8] and to understand carbon flux from plants to soil organisms [9] or within plants in different seasons [10] or under stress [11]. Similarly, the pioneering work of Rittenberg and Foster [12] on stable isotope dilution analysis revolutionized the ability for quantitative analysis of low abundance labile compounds and quantitative analysis of such compounds in vivo [13-15]. Stable isotope dilution has become the de facto standard for analysis of phytohormones and related compounds in plant tissues [16,17].In the post-genomic era of biological research, there has been increasing interest in making the connections between gene expression and the mechanisms of metabolic regulation in response to internal stimula
Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows I: Nonequillibrium Coolant Formation
William J Gray,Evan Scannapieco
Physics , 2010,
Abstract: We use high-resolution three-dimensional adaptive mesh refinement simulations to investigate the interaction of high-redshift galaxy outflows with low-mass virialized clouds of primordial composition. While atomic cooling allows star formation in objects with virial temperatures above $10^4$ K, "minihaloes" below this threshold are generally unable to form stars by themselves. However, these objects are highly susceptible to triggered star formation, induced by outflows from neighboring high-redshift starburst galaxies. Here we conduct a study of these interactions, focusing on cooling through non-equilibrium molecular hydrogen (H$_2$) and hydrogen deuteride (HD) formation. Tracking the non-equilibrium chemistry and cooling of 14 species and including the presence of a dissociating background, we show that shock interactions can transform minihaloes into extremely compact clusters of coeval stars. Furthermore, these clusters are all less than $\approx 10^6 M_\odot,$ and they are ejected from their parent dark matter halos: properties that are remarkably similar to those of the old population of globular clusters.
Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows III: Observability and Connection to Halo Globular Clusters
William J Gray,Evan Scannapieco
Physics , 2011, DOI: 10.1088/0004-637X/742/2/100
Abstract: The early universe hosted a large population of low-mass virialized "minihalos," that were not massive enough to form stars on their own. While most minihalos were photoevaporated by ionizing photons from star-forming galaxies, these galaxies also drove large outflows, which in some cases would have reached the minihalos in advance of ionization fronts. In the previous papers in this series, we carried out high-resolution, three-dimensional adaptive mesh refinement simulations of outflow-minihalo interactions that included non-equilibrium chemistry, radiative cooling, and turbulent mixing. We found that, for a fiducial set of parameters, minihalos were transformed into dense, chemically homogenous stellar clusters. Here we conduct a suite of simulations that follow these interactions over a wide range of parameters including minihalo mass, minihalo formation redshift, outflow energy, outflow redshift, distance, concentration, and spin. In almost all cases, the shocked minihalos form molecules through nonequillibrium reactions and then cool rapidly to become compact, chemically-homogenous stellar clusters. Furthermore, we show that the unique properties of these clusters make them a prime target for direct study with the next generation of telescopes, and that there are many reasons to suspect that their low-redshift counterparts are the observed population of halo globular clusters.
Atomic Chemistry in Turbulent Astrophysical Media II: Effect of the Redshift Zero Metagalactic Background
William J Gray,Evan Scannapieco
Physics , 2015,
Abstract: We carry out direct numerical simulations of turbulent astrophysical media exposed to the redshift zero metagalactic background. The simulations assume solar composition and explicitly track ionizations, recombinations, and ion-by-ion radiative cooling for hydrogen, helium, carbon, nitrogen, oxygen, neon, sodium, magnesium, silicon, sulfur, calcium, and iron. Each run reaches a global steady state that not only depends on the ionization parameter, $U,$ and mass-weighted average temperature, $T_{\rm MW},$ but also on the the one-dimensional turbulent velocity dispersion, \soned. We carry out runs that span a grid of models with $U$ ranging from 0 to 10$^{-1}$ and \soned\ ranging from 3.5 to 58 km s$^{-1}$, and we vary the product of the mean density and the driving scale of the turbulence, $nL,$ which determines the average temperature of the medium, from $nL =10^{16}$ to $nL =10^{20}$ cm$^{-2}$. The turbulent Mach numbers of our simulations vary from $M \approx 0.5$ for the lowest velocity dispersions cases to $M \approx 20$ for the largest velocity dispersion cases. When $M \lesssim1,$ turbulent effects are minimal, and the species abundances are reasonably described as those of a uniform photoionized medium at a fixed temperature. On the other hand, when $M \gtrsim 1,$ dynamical simulations such as the ones carried out here are required to accurately predict the species abundances. We gather our results into a set of tables, to allow future redshift zero studies of the intergalactic medium to account for turbulent effects.
Page 1 /413522
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.