7,835 research outputs found

    Key to Florida Alydidae (Hemiptera: Heteroptera) and selected exotic pest species

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    A key to the fourteen native Florida species and seven exotic pest species of Alydidae is presented here. The key uses external, non-genitalic morphology and allows for rapid separation of the native species and exotic pests included herein

    Key to Florida Alydidae (Hemiptera: Heteroptera) and selected exotic pest species

    Get PDF
    A key to the fourteen native Florida species and seven exotic pest species of Alydidae is presented here. The key uses external, non-genitalic morphology and allows for rapid separation of the native species and exotic pests included herein

    Defining What to Regulate: Silica and the Problem of Regulatory Categorization

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    This article examines the history of human exposure to silica, the second most common element on earth, to explore the problem of categorizing substances for regulatory purposes and the role interest groups play in developing policy. The regulatory history of silica teaches three important lessons: First, the most compelling account of the cycle of action and inaction on the part of regulators is the one based on interest groups. Second, knowledge about hazards is endogenous - it arises in response to outside events, to regulations, and to interest groups. Accepting particular states of knowledge as definitive is thus a mistake, as is failing to consider the incentives for knowledge production created by regulatory measures. Third, the rise of the trial bar as an interest group means that the problems of silica exposure and similar occupational hazards cannot simply be left to the legal system to resolve through individual tort actions. We suggest that by understanding market forces, regulators can harness the energy of interest groups to create better solutions to addressing the problems of silica exposure, as well as other workplace health and safety issues

    Optical spectroscopy of two overlapping, flux-density-limited samples of radio sources in the North Ecliptic Cap, selected at 38 MHz and 151 MHz

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    We present the results of optical spectroscopy of two flux-density-limited samples of radio sources selected at frequencies of 38 and 151 MHz in the same region around the North Ecliptic Cap, the 8C-NEC and 7C-III samples respectively. Both samples are selected at flux density levels ~20 times fainter than samples based on the 3C catalogue. They are amongst the first low-frequency selected samples with no spectral or angular size selection for which almost complete redshift information has been obtained and they will therefore provide a valuable resource for understanding the cosmic evolution of radio sources and their hosts and environments. The 151-MHz 7C-III sample is selected to have S_151 >=0.5 Jy and is the more spectroscopically complete; out of 54 radio sources fairly reliable redshifts have been obtained for 44 objects. The 8C sample has a flux limit of S_38 >=1.3 Jy and contains 58 sources of which 46 have fairly reliable redshifts. We discuss possible biases in the observed redshift distribution, and some interesting individual objects. Using the 8C-NEC and 7C-III samples in conjunction, we form the first sample selected on low-frequency flux in the rest-frame of the source, rather than the usual selection on flux density in the observed frame. This allows us to remove the bias associated with an increasing rest-frame selection frequency with redshift. We investigate the difference this selection makes to correlations of radio source properties with redshift and luminosity. We show in particular that flux-density-based selection leads to an overestimate of the steepness of the correlation of radio source size with redshift. (abridged)Comment: 22 pages, 10 figures, accepted by MNRA

    Numerical wave optics and the lensing of gravitational waves by globular clusters

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    We consider the possible effects of gravitational lensing by globular clusters on gravitational waves from asymmetric neutron stars in our galaxy. In the lensing of gravitational waves, the long wavelength, compared with the usual case of optical lensing, can lead to the geometrical optics approximation being invalid, in which case a wave optical solution is necessary. In general, wave optical solutions can only be obtained numerically. We describe a computational method that is particularly well suited to numerical wave optics. This method enables us to compare the properties of several lens models for globular clusters without ever calling upon the geometrical optics approximation, though that approximation would sometimes have been valid. Finally, we estimate the probability that lensing by a globular cluster will significantly affect the detection, by ground-based laser interferometer detectors such as LIGO, of gravitational waves from an asymmetric neutron star in our galaxy, finding that the probability is insignificantly small.Comment: To appear in: Proceedings of the Eleventh Marcel Grossmann Meetin

    The role of the maternal immune system in the regulation of human birth weight

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    This is the accepted manuscript version. It will be embargoed until 12 months after publication by RSC. The final version is available from RCS at http://rstb.royalsocietypublishing.org/content/370/1663/20140071.longHuman birth weight is subject to stabilizing selection. Large babies are at risk of obstetric complications such as obstructed labour, which endangers both mother and child. Small babies are also at risk with reduced survival. Fetal growth requires remodeling of maternal spiral arteries to provide an adequate maternal blood supply to the placenta. This arterial transformation is achieved by placental trophoblast cells, which invade into the uterine wall. Under invasion is associated with fetal growth restriction; but if invasion is excessive large babies can result. A growing body of evidence suggests that this process is controlled by interactions between KIR receptors expressed on maternal uterine NK cells (uNK) and their corresponding HLA-C ligands on invading trophoblast. Mothers with the KIR AA genotype and a fetus with a paternal HLA-C2 allele tend to have small babies, because this combination inhibits cytokine secretion by uNK. Mothers with the activating KIR2DS1 gene and an HLA-C2 fetus are more likely to have large babies. When KIR2DS1 binds to HLA-C2 this increases secretion of cytokines that enhance trophoblast invasion. We conclude that specific combinations of the highly polymorphic gene systems, KIR and HLAC, contribute to successful reproduction by maintaining birth weight between two extremes.This work was supported by funding from the Wellcome Trust [090108/Z/09/Z], [085992/Z/08/Z] and the British Heart Foundation [PG/09/077/27964]. This work was also supported by a Frederick National Laboratory for Cancer Research Contract [HHSN261200800001E] and by the Intramural Research Program of National Institutes of Health, Frederick National Laboratory, Center for Cancer Research. The authors also thank the Centre for Trophoblast Research, Cambridge for generous support

    Functional Ablation of pRb Activates Cdk2 and Causes Antiestrogen Resistance in Human Breast Cancer Cells

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    Estrogens are required for the proliferation of hormone dependent breast cancer cells, making estrogen receptor (ER) positive tumors amenable to endocrine therapies such as antiestrogens. However, resistance to these agents remains a significant cause of treatment failure. We previously demonstrated that inactivation of the retinoblastoma protein (pRb) family tumor suppressors causes antiestrogen resistance in MCF-7 cells, a widely studied model of estrogen responsive human breast cancers. In this study, we investigate the mechanism by which pRb inactivation leads to antiestrogen resistance. Cdk4 and cdk2 are two key cell cycle regulators that can phosphorylate and inactivate pRb, therefore we tested whether these kinases are required in cells lacking pRb function. pRb family members were inactivated in MCF-7 cells by expressing polyomavirus large tumor antigen (PyLT), and cdk activity was inhibited using the cdk inhibitors p16INK4A and p21Waf1/Cip1. Cdk4 activity was no longer required in cells lacking functional pRb, while cdk2 activity was required for proliferation in both the presence and absence of pRb function. Using inducible PyLT cell lines, we further demonstrated that pRb inactivation leads to increased cyclin A expression, cdk2 activation and proliferation in antiestrogen arrested cells. These results demonstrate that antiestrogens do not inhibit cdk2 activity or proliferation of MCF-7 cells in the absence of pRb family function, and suggest that antiestrogen resistant breast cancer cells resulting from pRb pathway inactivation would be susceptible to therapies that target cdk2

    A New Framework for Network Disruption

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    Traditional network disruption approaches focus on disconnecting or lengthening paths in the network. We present a new framework for network disruption that attempts to reroute flow through critical vertices via vertex deletion, under the assumption that this will render those vertices vulnerable to future attacks. We define the load on a critical vertex to be the number of paths in the network that must flow through the vertex. We present graph-theoretic and computational techniques to maximize this load, firstly by removing either a single vertex from the network, secondly by removing a subset of vertices.Comment: Submitted for peer review on September 13, 201
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