2,993 research outputs found

    Alcohol and Student Performance: Estimating the Effect of Legal Access

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    We consider the effect of legal access to alcohol on student achievement. We first estimate the effect using an RD design but argue that this approach is not well suited to the research question in our setting. Our preferred approach instead exploits the longitudinal nature of the data, identifying the effect by measuring the extent to which a studentā€™s performance changes after he gains legal access to alcohol, controlling flexibly for the expected evolution of grades as students make progress towards their degrees. We find that studentsā€™ grades fall below their expected levels upon being able to drink legally, but by less than previously documented. We also show that there are effects on women and that the effects are persistent.

    Alcohol and Student Performance: Estimating the Effect of Legal Access

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    We consider the effect of legal access to alcohol, which is known to increase drinking behavior, on academic performance. We first estimate the effect using an RD design but argue that this approach is not well-suited to the research question in our setting. Our preferred approach instead exploits the longitudinal nature of the data, essentially identifying the effect by comparing a student's academic performance before and after turning 21. We find that students' grades fall below their expected levels upon being able to drink legally, but by less than previously documented. We also show that there are effects on women and that the effects are persistent. The main results are robust to the inclusion of individual fixed effects, individual trends, and individual quadratics, in addition to other controls, that account for the expected evolution of performance as students make progress towards their degrees.alcohol, post-secondary education, minimum legal drinking age

    A Mapping of the Present and Past Forest-types of Prince Edward Island

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    Our aim was to produce maps showing the distribution on Prince Edward Island of five forest-types previously identified from a TWINSPAN analysis of ground flora data collected at 1200 sampling points in a field survey. For this purpose we had available two databases: one on the composition of the tree canopy of 82,957 forest stands, as determined by photointerpretation of a 1990 aerial photographic survey of the island; the other on the drainage properties of the same stands from a published soil survey. The tree canopy and drainage criteria for sorting these stands into five stand-types were chosen in the light of the equivalent properties of the TWINSPAN forest-types as evident from the field survey. These criteria were perfected in four trial computer-sortings, followed by the computer-printing of maps showing the distribution of the standtypes. These maps, which were then evaluated by comparing them with the properties of the TWINSPAN forest-types, are the first fine-scale maps of the main forest-types of the island. They reveal that, of the three “primary” forest-types, the upland hardwood forest occurs especially in the central and south-eastern hill-lands, as well as in scattered parcels elsewhere, whereas the Black Spruce forest and the wet species-rich woodland occur primarily in areas of lower elevation in the east and west of the island. The two forest-types resulting from human disturbance, the White Spruce woods and the “disturbed forest”, have a more scattered distribution, with the White Spruce woods being found especially in the central and eastern parts of the island and the disturbed forest in the west and east of the island. A secondary aim was to map the conjectured distribution before European settlement of the three primary forest-types: two maps have been produced, one showing the distribution of upland hardwood forest, the other of the wet forest-types

    Repression of human activation induced cytidine deaminase by miR-93 and miR-155

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    BACKGROUND: Activation Induced cytidine Deaminase (AID) targets the immunoglobulin genes of activated B cells, where it converts cytidine to uracil to induce mutagenesis and recombination. While essential for immunoglobulin gene diversification, AID misregulation can result in genomic instability and oncogenic transformation. This is classically illustrated in Burkitt's lymphoma, which is characterized by AID-induced mutation and reciprocal translocation of the c-MYC oncogene with the IgH loci. Originally thought to be B cell-specific, AID now appears to be misexpressed in several epithelial cancers, raising the specter that AID may also participate in non-B cell carcinogenesis. METHODS: The mutagenic potential of AID argues for the existence of cellular regulators capable of repressing inappropriate AID expression. MicroRNAs (miRs) have this capacity, and we have examined the publically available human AID EST dataset for miR complementarities to the human AID 3'UTR. In this work, we have evaluated the capacity of two candidate miRs to repress human AID expression in MCF-7 breast carcinoma cells. RESULTS: We have discovered moderate miR-155 and pronounced miR-93 complementary target sites encoded within the human AID mRNA. Luciferase reporter assays indicate that both miR-93 and miR-155 can interact with the 3'UTR of AID to block expression. In addition, over-expression of either miR in MCF-7 cells reduces endogenous AID protein, but not mRNA, levels. Similarly indicative of AID translational regulation, depletion of either miR in MCF-7 cells increases AID protein levels without concurrent increases in AID mRNA. CONCLUSIONS: Together, our findings demonstrate that miR-93 and miR-155 constitutively suppress AID translation in MCF-7 cells, suggesting widespread roles for these miRs in preventing genome cytidine deaminations, mutagenesis, and oncogenic transformation. In addition, our characterization of an obscured miR-93 target site located within the AID 3'UTR supports the recent suggestion that many miR regulations have been overlooked due to the prevalence of truncated 3'UTR annotations

    Momentum average approximation for models with electron-phonon coupling dependent on the phonon momentum

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    We generalize the momentum average (MA) approximation to study the properties of models with momentum-dependent electron-phonon coupling. As in the case of the application of the original MA to the Holstein model, the results are analytical, numerically trivial to evaluate, exact for both zero bandwidth and for zero electron-phonon coupling, and are accurate everywhere in parameter space. Comparison with available numerical data confirms this accuracy. We then show that further improvements can be obtained based on variational considerations, using the one-dimensional breathing-mode Hamiltonian as a specific example. For example, by using this variational MA, we obtain ground state energies within at most 0.3% error of the numerical data.Comment: 15 pages, 10 figure

    New Records of aphids (Hemiptera: Aphididae) on Industrial Hemp in the US Midwest

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    Industrial hemp (Cannabis sativa L.) production in the USA is increasing, and with it the list of insects colonizing the crop. In this article, we report new records of Aphis craccivora Koch 1854, Aphis fabae Scopoli, Aphis gossypiiGlover 1763, Aphis spiraecola Patch 1914 and Myzus persicae (Sulzer 1776) on industrial hemp in East Lansing, Michigan in fall 2020. In addition, between 2017 and 2020, the number of suction trap sites detecting P. cannabisincreased, and as well as the number of sites with multiple weeks of detections. The timing of detection changed, from only late season (fall migrants) in 2017, to catches spanning spring, summer, and fall in 2019 and 2020. These changes likely reflect the increase in industrial hemp production in the landscape in the Midwestern US
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