2,890 research outputs found

    Frequency-modulated nuclear localization bursts coordinate gene regulation

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    In yeast, the transcription factor Crz1 is dephosphorylated and translocates into the nucleus in response to extracellular calcium. Here we show, using time-lapse microscopy, that Crz1 exhibits short bursts of nuclear localization (typically lasting 2 min) that occur stochastically in individual cells and propagate to the expression of downstream genes. Strikingly, calcium concentration controls the frequency, but not the duration, of localization bursts. Using an analytic model, we also show that this frequency modulation of bursts ensures proportional expression of multiple target genes across a wide dynamic range of expression levels, independent of promoter characteristics. We experimentally confirm this theory with natural and synthetic Crz1 target promoters. Another stress-response transcription factor, Msn2, exhibits similar, but largely uncorrelated, localization bursts under calcium stress suggesting that frequency-modulation regulation of localization bursts may be a general control strategy used by the cell to coordinate multi-gene responses to external signals

    Thermal Degradation of Pigments and Relative Biochemical Changes in Cherries and Apricots

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    The extent and nature of biochemical changes that take place in canned fruits during storage temperatures above freezing have been reviewed and discussed by Pederson, et al. (1947). These changes include loss in nutritive value, e.g. ascorbic acid, thiamine (Brenner, et al., 1948) and deterioration of color (Tressler, et al., 1955). Bauernfeind (1953) reported that canned peaches, apricots, and sweet cherries, after a few months of storage at 70°F, frequently undergo changes such as destruction of anthocyanin and carotenoid pigments with the subsequent formation of brown colored compounds. Darkening of fruit-color eventually results in their unacceptability at consumer level. Preference for fruit is mainly based upon the attractive appearance of the products. Thus, color is an important factor governing the quality of fruits and fruit products. In earlier studies, conducted elsewhere, emphasis was placed on effects of low storage temperatures on the quality of canned apricots and cherries. Paucity of scientific literature on the stability of processed apricots and cherries gave impetus to a study of the comparative influence of high storage temperatures and their duration, as such tests will have considerable economic bearing upon storing and shipping processed products to tropical countries. This thesis presents the effects of storage temperatures (40, 70, 100, and 120° F) and their duration (16 weeks) on colors (anthocyanins and carotenoids), total titratable acidity, pH, viscosity, carbohydrates (total 2 and free reducing sugars, pectins), volatile reducing substances, hydroxymethyl furfural, and organoleptic quality of canned apricots and cherries

    Automated data acquisition and reduction system for torsional braid analyzer

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    Automated Data Acquisition and Reduction System (ADAR) evaluates damping coefficient and relative rigidity by storing four successive peaks of waveform and time period between two successive peaks. Damping coefficient and relative rigidity are then calculated and plotted against temperature or time in real time

    Validation of the Association of Fraternity/Sorority Advisors Core Competency Model

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    Despite its utility, the Association of Fraternity/Sorority Advisors (AFA) revised Core Competency model has not been validated; therefore, we conducted two studies to validate the AFA Core Competency Model. First, we developed a performance evaluation tool, applicable across different positions. We then linked Core Competency self-assessment scores to supervisor ratings of performance to assess the extent to which competencies related to job performance. Although not all Core Competencies related to each performance dimension, each Core Competency correlated with at least one dimension of performance. In short, the results suggest that the Core Competencies are, in general, related to job performance, and appropriate to use for personnel development

    Coherent manipulation of electron spins up to ambient temperatures in Cr5+^{5+}(S=1/2) doped K3_3NbO8_8

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    We report coherent spin manipulation on Cr5+^{5+} (\emph{S} = 1/2, \emph{I} = 0) doped K3_3NbO8_8, which constitutes a dilute two-level model relevant for use as a spin qubit. Rabi oscillations are observed for the first time in a spin system based on transition metal oxides up to room temperature. At liquid helium temperature the phase coherence relaxation time \emph{T2T_2} reaches ∼10\sim 10 μ\mus and, with a Rabi frequency of 20 MHz, yields a single qubit figure of merit \emph{QMQ_M} of about 500. This shows that a diluted ensemble of Cr5+^{5+} (\emph{S} = 1/2) doped K3_3NbO8_8 is a potential candidate for solid-state quantum information processing.Comment: 4 page

    Atomic Force Microscopy of Chromatin

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    Phytochemical Screening of Methanolic Extract and Antibacterial Activity of Active Principles of Hepatoprotective Herb, Eclipta alba

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    Aerial parts of Eclipta alba are used traditionally for the treatment of several diseases of liver, skin and stomach. Methanolic extract and active principle compound of a well known Indian hepatoprotective herb, Eclipta alba was tested for in vitro antimicrobial studies. It was evaluated using zone of inhibition studies and minimum inhibitory concentration. The extract exhibited activity against all six strains studied. Phytochemical screening of the extract revealed the presence of tannins, flavonoids, coumestans, saponins and alkaloids etc. Ethylacetate fraction and further pure isolated wedelolactone showed enhanced antimicrobial activity. Staphylococcus epidermidis, Staphylococcus aureus and Salmonella typhimurium were most susceptible. Shigella flexneri was the most resistant bacterial strain. These results suggest coumestans/wedelolactone as a promising antimicrobial agent
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