609 research outputs found

    Trajectory and propulsion characteristics of comet rendezvous opportunities

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    Trajectory and propulsion characteristics of spacecraft rendezvous mission opportunities to comets during 1975 to 199

    Pioneer Mars 1979 mission options

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    A preliminary investigation of lower cost Mars missions which perform useful exploration objectives after the Viking/75 mission was conducted. As a study guideline, it was assumed that significant cost savings would be realized by utilizing Pioneer hardware currently being developed for a pair of 1978 Venus missions. This in turn led to the additional constraint of a 1979 launch with the Atlas/Centaur launch vehicle which has been designated for the Pioneer Venus missions. Two concepts, using an orbiter bus platform, were identified which have both good science potential and mission simplicity indicative of lower cost. These are: (1) an aeronomy/geology orbiter, and (2) a remote sensing orbiter with a number of deployable surface penetrometers

    The accessible regions presentation of gravity-assisted trajectories using Jupiter

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    Accessibility of solar system regions to earth launched spacecraft using Jupiter gravity- assisted trajectorie

    Pharmacological activation of the nuclear receptor REV-ERB reverses cognitive deficits and reduces amyloid-β burden in a mouse model of Alzheimer’s disease

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    Alzheimer’s disease currently lacks treatment options that effectively reverse the biological/anatomical pathology and cognitive deficits associated with the disease. Loss of function of the nuclear receptor REV-ERB is associated with reduced cognitive function in mouse models. The effect of enhanced REV-ERB activity on cognitive function has not been examined. In this study, we tested the hypothesis that enhanced REV-ERB function may enhance cognitive function in a model of Alzheimer’s disease. We utilized the REV-ERB agonist SR9009 to pharmacologically activate the activity of REV-ERB in the SAMP8 mouse model of Alzheimer’s disease. SR9009 reversed cognitive dysfunction of an aged SAMP8 mouse in several behavioral assays including novel object recognition, T-maze foot shock avoidance, and lever press operant conditioning task assessments. SR9009 treatment reduced amyloid-β 1–40 and 1–42 levels in the cortex, which is consistent with improved cognitive function. Furthermore, SR9009 treatment led to increased hippocampal PSD-95, cortical synaptophysin expression and the number of synapses suggesting improvement in synaptic function. We conclude that REV-ERB is a potential target for treatment of Alzheimer’s disease.</div

    The Attorney-Client Privilege and the Work-Product Doctrine in Michigan

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    In Upjohn Co v. United States, the United States Supreme Court acknowledged that the attorney-client privilege - the oldest of the privileges for confidential communications known to the common law - has the crucial purpose of encourag[ing] full and frank communication between attorneys and their clients and thereby promote[s] broader public interests in the observance of law and administration of justice. Similarly, in Hickman v Taylor, the Court stressed the importance of the work-product doctrine, noting that [n]ot even the most liberal of discovery theories can justify unwarranted inquiries into the files and the mental impressions of an attorney. It is beyond question that, at a theoretical level, the attorney-client privilege and the work-product doctrine serve significant interests and that, at a practical level, attorneys constantly encounter issues involving these principles. Nevertheless, many attorneys do not acquire their familiarity with these crucial principles in any systematic way. Law school courses and casebooks often treat these principles superficially, and busy practicing lawyers tend to research specific issues only as they arise in the course of their work. As a result, many attorneys (and perhaps some judges) may not clearly understand the significance, scope, and limits of these doctrines. This publication is an attempt to solve this problem by offering a systematic and thorough examination of the attorney-client privilege and the work-product doctrine under Michigan law. Part II of this text addresses the attorney-client privilege; Part III addresses the work-product doctrine; and Part IV addresses ethics concepts of confidences and secrets. Wherever possible, Michigan authority has been cited and quoted. In some instances, federal cases are instructive in interpreting Michigan law or in filling an apparent gap in Michigan law; under those circumstances, the text freely cites and quotes from federal authority. The goal is to provide a comprehensive examination of these principles as interpreted by the Michigan courts.https://repository.law.umich.edu/books/1117/thumbnail.jp

    Childhood and Adolescent Pesticide Exposure and Breast Cancer Risk

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    To date, epidemiological studies have not strongly supported an association between pesticide exposure and breast cancer. However, few previous studies had the ability to assess specific time periods of exposure. Studies that relied on adult serum levels of metabolites of organochlorine pesticides may not accurately reflect exposure during developmental periods. Further, exposure assessment often occurred after diagnosis and key tumor characteristics, such as hormone receptor status, have rarely been available to evaluate tumor-subtype specific associations. We examine the association between pesticide exposure during childhood and adolescence and breast cancer risk in the prospective Sister Study cohort (N=50,844 women) to assess this relation by tumor subtype

    Sea ice decline drives biogeographical shifts of key Calanus species in the central Arctic Ocean

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    In recent decades, the central Arctic Ocean has been experiencing dramatic decline in sea ice coverage, thickness and extent, which is expected to have a tremendous impact on all levels of Arctic marine life. Here, we analyze the regional and temporal changes in pan-Arctic distribution and population structure of the key zooplankton species Calanus glacialis and C. hyperboreus in relation to recent changes in ice conditions, based on historical (1993–1998) and recent (2007–2016) zooplankton collections and satellite-based sea ice observations. We found strong correlations between Calanus abundance/population structure and a number of sea ice parameters. These relationships were particularly strong for C. glacialis, with higher numbers being observed at locations with a lower ice concentration, a shorter distance to the ice edge, and more days of open water. Interestingly, early stages of C. hyperboreus followed the same trends, suggesting that these two species substantially overlap in their core distribution area in the Arctic Ocean. Calanus glacialis and C. hyperboreus have been historically classified as shelf versus basin species, yet we conclude that both species can inhabit a wide range of bottom depths and their distribution in the Arctic Ocean is largely shaped by sea ice dynamics. Our data suggest that the core distribution patterns of these key zooplankton are shifting northwards with retreating sea ice and changing climate conditions.publishedVersio

    Comparative analysis of Calanus finmarchicus demography at locations around the Northeast Atlantic

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    Standardized time-series sampling was carried out throughout 1997 at seven locations around the Northeast Atlantic to investigate regional variations in the seasonal demography of Calanus finmarchicus. Sites ranged from an inshore location in the North Sea, where C. finmarchicus formed only a small component of the zooplankton (2000 mgC m-2 during spring and summer). The internal consistency of the demographic time-series from each site was investigated by three partial models of life-cycle processes. In general, the demography of late copepodites could be accounted for by a relatively simple forecast model of stage development and diapause. However, there was a large discrepancy between nowcast estimates of egg production based on female abundance, temperature, and chlorophyll, and hindcast simulations of the egg production required to account for the observed abundance of early copepodite stages. The results point to a gap in our understanding of seasonal variations in rates of egg production and/or survival of nauplii. Overall, the population sampled at Weathership M appeared to be reasonably self-contained, but all other sites were reliant on invasion of overwintered stock in spring. At least two generations were observed at all but one site, but the extent to which these were generated by discrete bursts of egg production varied between sites and seemed to be partly dependent on the proximity to an overwintering location
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