142 research outputs found

    Abfs and Cbfs in Cotton (Gossypium Hirsutum): A Characterization and Functional Analysis in Response to Abiotic Stress

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    Abiotic stress is pernicious; every year causing substantial reductions in agricultural yield. Despite this, due to the complex nature of the plant response, our current understanding of the molecular mechanisms and signaling pathways is limited. Among the gene families shown to play a role in dehydration and low temperature tolerance are the ABFs and CBFs. Both are small families of transcription factors, are expressed in response to abiotic stress, and have been shown to increase abiotic stress tolerance when ectopically expressed. Here, both of these families are isolated and functionally characterized in G. hirsutum (cotton), the most important global natural fiber source. Gene expression analyses illustrate how these genes respond to abiotic stress, and ectopic expression in Arabidopsis illustrates their functionality. Ectopic expression of abiotic stress-related genes has often been shown to increase stress tolerance, however, at a developmental cost. Therefore, a more in-depth understanding of the abiotic stress response is necessary to develop crops able to withstand abiotic stress and at the same time minimize developmental delays.Biochemistry & Molecular Biolog

    Measuring movement fluency during the sit-to-walk task

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    Restoring movement fluency is a key focus for physical rehabilitation; it's measurement, however, lacks objectivity. The purpose of this study was to find whether measurable movement fluency variables differed between groups of adults with different movement abilities whilst performing the sit-to-walk (STW) movement. The movement fluency variables were: (1) hesitation during movement (reduction in forward velocity of the centre of mass; CoM), (2) coordination (percentage of temporal overlap of joint rotations) and (3) smoothness (number of inflections in the CoM jerk signal)

    State of the Art in Large-Scale Soil Moisture Monitoring

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    Soil moisture is an essential climate variable influencing land atmosphere interactions, an essential hydrologic variable impacting rainfall runoff processes, an essential ecological variable regulating net ecosystem exchange, and an essential agricultural variable constraining food security. Large-scale soil moisture monitoring has advanced in recent years creating opportunities to transform scientific understanding of soil moisture and related processes. These advances are being driven by researchers from a broad range of disciplines, but this complicates collaboration and communication. For some applications, the science required to utilize large-scale soil moisture data is poorly developed. In this review, we describe the state of the art in large-scale soil moisture monitoring and identify some critical needs for research to optimize the use of increasingly available soil moisture data. We review representative examples of 1) emerging in situ and proximal sensing techniques, 2) dedicated soil moisture remote sensing missions, 3) soil moisture monitoring networks, and 4) applications of large-scale soil moisture measurements. Significant near-term progress seems possible in the use of large-scale soil moisture data for drought monitoring. Assimilation of soil moisture data for meteorological or hydrologic forecasting also shows promise, but significant challenges related to model structures and model errors remain. Little progress has been made yet in the use of large-scale soil moisture observations within the context of ecological or agricultural modeling. Opportunities abound to advance the science and practice of large-scale soil moisture monitoring for the sake of improved Earth system monitoring, modeling, and forecasting

    Supersymmetric Dark Matter

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    There is almost universal agreement among astronomers that most of the mass in the Universe and most of the mass in the Galactic halo is dark. Many lines of reasoning suggest that the dark matter consists of some new, as yet undiscovered, weakly-interacting massive particle (WIMP). There is now a vast experimental effort being surmounted to detect WIMPS in the halo. The most promising techniques involve direct detection in low-background laboratory detectors and indirect detection through observation of energetic neutrinos from annihilation of WIMPs that have accumulated in the Sun and/or the Earth. Of the many WIMP candidates, perhaps the best motivated and certainly the most theoretically developed is the neutralino, the lightest superpartner in many supersymmetric theories. We review the minimal supersymmetric extension of the Standard Model and discuss prospects for detection of neutralino dark matter. We review in detail how to calculate the cosmological abundance of the neutralino and the event rates for both direct- and indirect-detection schemes, and we discuss astrophysical and laboratory constraints on supersymmetric models. We isolate and clarify the uncertainties from particle physics, nuclear physics, and astrophysics that enter at each step in the calculation. We briefly review other related dark-matter candidates and detection techniques.Comment: The complete postscript file is available at ftp://ftp.npac.syr.edu/pub/users/jungman/susyreview/susyreview.ps.Z The TeX source and figures (plain TeX; macros included) are at ftp://ftp.npac.syr.edu/pub/users/jungman/susyreview/susyreview.tar.Z Full paper NOT submitted to lanl archive: table of contents only. To appear in Physics Report

    The density and peculiar velocity fields of nearby galaxies

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    We review the quantitative science that can be and has been done with redshift and peculiar velocity surveys of galaxies in the nearby universe. After a brief background setting the cosmological context for this work, the first part of this review focuses on redshift surveys. The practical issues of how redshift surveys are carried out, and how one turns a distribution of galaxies into a smoothed density field, are discussed. Then follows a description of major redshift surveys that have been done, and the local cosmography out to 8,000 km/s that they have mapped. We then discuss in some detail the various quantitative cosmological tests that can be carried out with redshift data. The second half of this review concentrates on peculiar velocity studies, beginning with a thorough review of existing techniques. After discussing the various biases which plague peculiar velocity work, we survey quantitative analyses done with peculiar velocity surveys alone, and finally with the combination of data from both redshift and peculiar velocity surveys. The data presented rule out the standard Cold Dark Matter model, although several variants of Cold Dark Matter with more power on large scales fare better. All the data are consistent with the hypothesis that the initial density field had a Gaussian distribution, although one cannot rule out broad classes of non-Gaussian models. Comparison of the peculiar velocity and density fields constrains the Cosmological Density Parameter. The results here are consistent with a flat universe with mild biasing of the galaxies relative to dark matter, although open universe models are by no means ruled out.Comment: In press, Physics Reports. 153 pages. gzip'ed postscript of text plus 20 embedded figures. Also available via anonymous ftp at ftp://eku.ias.edu/pub/strauss/review/physrep.p
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