4,415 research outputs found

    Assassin

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    What the Buck and Doe Dreamed

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    One Night Stand

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    Sunflowers

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    Arntson at Twenty-Three

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    Variability of Temperature and Salinity in the Middle Atlantic Bight and Gulf of Maine

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    Monitoring of the waters of the Middle Atlantic Bight and Gulf of Maine has been conducted by the MARMAP Ships of Opportunity Program since the early 1970's. Presented in this atlas are portrayals of the temporal and spatial patterns of surface and bottom temperature and surface salinity for these areas during the period 1978-1990. These patterns are shown in the form of time-space diagrams for single-year and multiyear (base period) time frames. Each base period figure shows thirteen-year (1978-1990) mean conditions, sample variance in the form of standard deviations of the measured values, and data locations. Each single-year figure displays annual conditions, sampling locations, and departures of annual conditions from the thirteen-year means, expressed as algebraic anomalies and standardized anomalies. (PDF file contains 112 pages.

    The CArG Boxes in the Promoter of the Arabidopsis Floral Organ Identity Gene APETALA3 Mediate Diverse Regulatory Effects

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    APETALA3 is a MADS box gene required for normal development of the petals and stamens in the Arabidopsis flower. Studies in yeast, mammals and plants demonstrate that MADS domain transcription factors bind with high affinity to a consensus sequence called the CArG box. The APETALA3 promoter contains three close matches to the consensus CArG box sequence. To gain insights into the APETALA3 regulatory circuitry, we have analyzed the APETALA3 promoter using AP3::uidA(GUS) fusions. 496 base pairs of APETALA3 promoter sequence 5′ to the transcriptional start directs GUS activity in the same temporal and spatial expression pattern as the APETALA3 RNA and protein in wild-type flowers. A synthetic promoter consisting of three tandem repeats of a 143 base pair sequence directs reporter gene activity exclusively to INTRODUCTION The developmental fate of the organs in the Arabidopsis flower is controlled by the homeotic floral organ identity genes. When the activity of a particular floral organ identity gene is lost due to mutation, there is a homeotic conversion of one organ type to another. For example, the APETALA3 (AP3) and PISTILLATA (PI) genes are necessary for the proper development of petals that develop in the second whorl and stamens that develop in the third whorl of the flower. In ap3 and pi mutants, sepals and carpels develop in positions normally occupied by petals and stamens respectively (Bowman et al., 1989; Jack et al., 1992). Accumulating genetic and molecular evidence suggests that the AP3 and PI proteins together make up the B class organ identity function and these two proteins are sufficient to direct the identity of petals and stamens in the flower. In support of this, ectopic expression of AP3 and/or PI throughout the flower leads to homeotic transformations. Specifically misexpression of AP3 (i.e. 35S::AP3) results in the development of stamens in place of carpels in the fourth whorl and misexpression of PI (i.e. 35S::PI) results in the development of petaloid sepals in place of sepals in the first whorl of the flower (Jack et al., 1994; Krizek and Meyerowitz, 1996). 35S::AP3 leads to fourth whorl organ identity changes because PI is transiently expressed in whorl four during early stages of flower petals and stamens in the flower. We have analyzed the role of the CArG boxes by site-specific mutagenesis and find that the three CArG boxes mediate discrete regulatory effects. Mutations in CArG1 result in a decrease in reporter expression suggesting that CArG1 is the binding site for a positively acting factor or factors. Mutations in CArG2 result in a decrease in reporter expression in petals, but the expression pattern in stamens is unchanged. By contrast, mutations in CArG3 result in an increase in the level of reporter gene activity during early floral stages suggesting that CArG3 is the binding site for a negatively acting factor

    Tax evasion and exchange equity: a reference-dependent approach

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    The standard portfolio model of tax evasion with a public good produces the perverse conclusion that when taxpayers perceive the public good to be under-/overprovided, an increase in the tax rate increases/decreases evasion. The author treats taxpayers as thinking in terms of gains and losses relative to an endogenous reference level, which reflects perceived exchange equity between the value of taxes paid and the value of public goods supplied. With these alternative behavioral assumptions, the author overturns the aforementioned result in a direction consistent with the empirical evidence. The author also finds a role for relative income in determining individual responses to a change in the marginal rate of tax
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