303 research outputs found

    Automation of shear-wave splitting parameter determination of local earthquakes at Yellowstone : application as indicator of crustal stress and temporal variation

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    Shear-wave splitting can be a useful technique for determining crustal stress fields in volcanic settings and temporal variations associated with activity. Splitting parameters were determined for a subset of local earthquakes recorded from 2000-2010 at Yellowstone. Analysis was automated using an unsupervised cluster analysis technique to determine optimum splitting parameters from 270 analysis windows for each event. Six stations clearly exhibit preferential fast polarization values sub-orthogonal to the direction of minimum horizontal compression. Yellowstone deformation results in a local crustal stress field differing from the regional field dominated by NE-SW extension, and fast directions reflect this difference rotating around the caldera maintaining perpendicularity to the rim. One station exhibits temporal variations concordant with identified periods of caldera subsidence and uplift. From splitting measurements, we calculated a crustal anisotropy of ~17-23% and crack density ~0.12-0.17 possibly resulting from stress-aligned fluid filled microcracks in the upper crust and an active hydrothermal system

    Accounting for the influence of temperature and location when predicting seagrass (halophila ovalis) photosynthetic performance

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    We show that the effect of temperature on photosynthesis of a widely distributed and ecological important seagrass species was not consistent among locations, with some evidence of acclimation to the local temperature range. This has important implications for modelling seagrass productivity and the impacts of light reduction on seagrass ecosystems. Reduced light availability is one of the main pressures negatively impacting on seagrass meadows worldwide. Our knowledge of seagrass photosynthetic characteristics is critical to predicting and managing impacts of light reducing activities but suffers from two critical information gaps: first, data is overwhelmingly derived from studies of leaf tissue and not for whole plants, and is unlikely to reflect whole plant performance under light reduction stress; and second, few studies have looked at spatial and temporal variability in photosynthetic performance of whole seagrasses. We investigated temporal and spatial variation at a range of temperatures for whole plants of Halophila ovalis, a widely distributed species, by measuring oxygen exchange of intact plants collected from four locations across a latitudinal gradient (10°) at three temperatures (17 °C, 23 °C, 28 °C). For all locations, temperature affected all photosynthetic parameters, with some parameters (NPmax, R, Ik) showing a distinct difference between tropical and temperate locations. For example, NPmax ranged from 1.35 ± 0.12 to 5 ± 0.16 mg O₂. g DW−1. hr−1 in temperate locations and from 4 ± 0.3 to 12 ± 0.68 mg O₂. g DW−1. hr−1 in the tropical location. However, the effect of temperature on photosynthesis was not consistent among locations, and often the rate of photosynthesis was greatest at temperatures approaching the mean month maximum temperature for the location, suggestive of acclimation. Time of year also affected photosynthetic rates and how temperature influenced those rates. We conclude that the application of P–I parameters to model, predict or manage the effect of light reduction of H. ovalis, and likely other seagrass species, may require site- and time-specific knowledge of P–I relationships

    Policy Momentum and Transgender Policy Inclusion: Explaining National Policy Change

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    Western democracies are experiencing a widespread shift towards greater recognition of transgender rights in public policy, yet the timing of policy change differs across states. This dissertation asks: What explains the timing of transgender-inclusive public policy change? To explain this variation, I develop an original theoretical framework called “policy momentum.” Unlike existing work on policy diffusion, which typically emphasizes either domestic or international processes, I theorize how the combined pressure from each level creates the conditions for policy change to occur. Empirically, I contrast two policy areas in Canada and Australia. First, I analyze the creation of national antidiscrimination policies to protect transgender individuals. Canada and Australia prohibited discrimination based on gender identity in 2017 and 2013, respectively. Second, I examine the timing of military policy changes. The Canadian Armed Forces lifted its ban on transgender people in 1992, whereas the Australian Defense Force repealed its ban in 2010. To explain the sequence of events that led to policy change in each case, I rely on 40 elite interviews and more than 15,000 pages of previously classified archival documents. I demonstrate how the timing of policy change in each case is best explained by the policy momentum framework. In the context of antidiscrimination legislation, Canada was primarily influenced by policy adoption across the provinces and, to a lesser extent, the desire to maintain Canada’s international reputation as a human rights leader. Australia, by comparison, was most strongly influenced by its international obligations but the experiences of subnational governments also informed the policy change process. In the more conservative issue area of military policy, the combination of domestic pressure through the judiciary and changes in practices among peer countries led both the Canadian Armed Forces and the Australian Defence Force to lift their bans on transgender military service. This dissertation thus contributes to our knowledge of LGBT+ politics and the creation of more inclusive public policies. It also advances public policy scholarship by creating a more holistic explanatory framework that integrates the multidirectional and multi-jurisdictional sources of pressure that together produce national policy change

    Reinfection with SARS-CoV-2 : discrete SIR (Susceptible, Infected, Recovered) modeling using empirical infection data

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    Background: The novel coronavirus SARS-CoV-2, which causes the COVID-19 disease, has resulted in a global pandemic. Since its emergence in December 2019, the virus has infected millions of people, caused the deaths of hundreds of thousands, and resulted in incalculable social and economic damage. Understanding the infectivity and transmission dynamics of the virus is essential to determine how best to reduce mortality while ensuring minimal social restrictions on the lives of the general population. Anecdotal evidence is available, but detailed studies have not yet revealed whether infection with the virus results in immunity. Objective: The objective of this study was to use mathematical modeling to investigate the reinfection frequency of COVID-19. Methods: We have used the SIR (Susceptible, Infected, Recovered) framework and random processing based on empirical SARS-CoV-2 infection and fatality data from different regions to calculate the number of reinfections that would be expected to occur if no immunity to the disease occurred. Results: Our model predicts that cases of reinfection should have been observed by now if primary SARS-CoV-2 infection did not protect individuals from subsequent exposure in the short term; however, no such cases have been documented. Conclusions: This work concludes that infection with SARS-CoV-2 provides short-term immunity to reinfection and therefore offers useful insight for serological testing strategies, lockdown easing, and vaccine development

    Using Mendelian randomization to determine causal effects of maternal pregnancy (intrauterine) exposures on offspring outcomes:Sources of bias and methods for assessing them

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    Mendelian randomization (MR), the use of genetic variants as instrumental variables (IVs) to test causal effects, is increasingly used in aetiological epidemiology. Few of the methodological developments in MR have considered the specific situation of using genetic IVs to test the causal effect of exposures in pregnant women on postnatal offspring outcomes. In this paper, we describe specific ways in which the IV assumptions might be violated when MR is used to test such intrauterine effects. We highlight the importance of considering the extent to which there is overlap between genetic variants in offspring that influence their outcome with genetic variants used as IVs in their mothers. Where there is overlap, and particularly if it generates a strong association of maternal genetic IVs with offspring outcome via the offspring genotype, the exclusion restriction assumption of IV analyses will be violated. We recommend a set of analyses that ought to be considered when MR is used to address research questions concerned with intrauterine effects on post-natal offspring outcomes, and provide details of how these can be undertaken and interpreted. These additional analyses include the use of genetic data from offspring and fathers, examining associations using maternal non-transmitted alleles, and using simulated data in sensitivity analyses (for which we provide code). We explore the extent to which new methods that have been developed for exploring violation of the exclusion restriction assumption in the two-sample setting (MR-Egger and median based methods) might be used when exploring intrauterine effects in one-sample MR. We provide a list of recommendations that researchers should use when applying MR to test the effects of intrauterine exposures on postnatal offspring outcomes and use an illustrative example with real data to demonstrate how our recommendations can be applied and subsequent results appropriately interpreted

    Concurrent MEK targeted therapy prevents MAPK pathway reactivation during BRAFV600E targeted inhibition in a novel syngeneic murine glioma model.

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    Inhibitors of BRAFV600E kinase are currently under investigations in preclinical and clinical studies involving BRAFV600E glioma. Studies demonstrated clinical response to such individualized therapy in the majority of patients whereas in some patients tumors continue to grow despite treatment. To study resistance mechanisms, which include feedback activation of mitogen-activated protein kinase (MAPK) signaling in melanoma, we developed a luciferase-modified cell line (2341luc) from a BrafV600E mutant and Cdkn2a- deficient murine high-grade glioma, and analyzed its molecular responses to BRAFV600E- and MAPK kinase (MEK)-targeted inhibition. Immunocompetent, syngeneic FVB/N mice with intracranial grafts of 2341luc were tested for effects of BRAFV600E and MEK inhibitor treatments, with bioluminescence imaging up to 14-days after start of treatment and survival analysis as primary indicators of inhibitor activity. Intracranial injected tumor cells consistently generated high-grade glioma-like tumors in syngeneic mice. Intraperitoneal daily delivery of BRAFV600E inhibitor dabrafenib only transiently suppressed MAPK signaling, and rather increased Akt signaling and failed to extend survival for mice with intracranial 2341luc tumor. MEK inhibitor trametinib delivered by oral gavage daily suppressed MAPK pathway more effectively and had a more durable anti-growth effect than dabrafenib as well as a significant survival benefit. Compared with either agent alone, combined BRAFV600E and MEK inhibitor treatment was more effective in reducing tumor growth and extending animal subject survival, as corresponding to sustained MAPK pathway inhibition. Results derived from the 2341luc engraftment model application have clinical implications for the management of BRAFV600E glioma

    “That’s not what we do”: evidence that normative change is a mechanism of action in group interventions

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    Group interventions for mental health have proved very effective, but there is little consensus on their mechanism of action. In the present study, we posit that normative change is a plausible mechanism and provide a test of this in an eating disorder prevention group program. Participants were 112 women aged 15-25 years with body, shape or weight concerns who completed five questionnaires across the four session group-based intervention. Results indicated that participants experienced a significant reduction in thin-ideal internalization, body dissatisfaction and dieting intentions across the course of the program. These decrements were preceded by changes in group norms. Changes in both descriptive norms and injunctive norms in the first half of the program predicted improvement in thin-ideal internalization, body dissatisfaction and dieting intentions in the second half. Implications for theoretical models of attitude change are discussed, as well as implications for group interventions more generally

    A phylogenomic analysis of Marek's disease virus reveals independent paths to virulence in Eurasia and North America

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    Virulence determines the impact a pathogen has on the fitness of its host, yet current understanding of the evolutionary origins and causes of virulence of many pathogens is surprisingly incomplete. Here, we explore the evolution of Marek's disease virus (MDV), a herpesvirus commonly afflicting chickens and rarely other avian species. The history of MDV in the 20th century represents an important case study in the evolution of virulence. The severity of MDV infection in chickens has been rising steadily since the adoption of intensive farming techniques and vaccination programs in the 1950s and 1970s, respectively. It has remained uncertain, however, which of these factors is causally more responsible for the observed increase in virulence of circulating viruses. We conducted a phylogenomic study to understand the evolution of MDV in the context of dramatic changes to poultry farming and disease control. Our analysis reveals evidence of geographical structuring of MDV strains, with reconstructions supporting the emergence of virulent viruses independently in North America and Eurasia. Of note, the emergence of virulent viruses appears to coincide approximately with the introduction of comprehensive vaccination on both continents. The time-dated phylogeny also indicated that MDV has a mean evolutionary rate of ~1.6 × 10−5 substitutions per site per year. An examination of gene-linked mutations did not identify a strong association between mutational variation and virulence phenotypes, indicating that MDV may evolve readily and rapidly under strong selective pressures and that multiple genotypic pathways may underlie virulence adaptation in MDV

    Reliability of Automated Biochemical Identification of Burkholderia pseudomallei Is Regionally Dependent

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    Misidentifications of Burkholderia pseudomallei as Burkholderia cepacia by Vitek 2 have occurred. Multidimensional scaling ordination of biochemical profiles of 217 Malaysian and Australian B. pseudomallei isolates found clustering of misidentified B. pseudomallei isolates from Malaysian Borneo. Specificity of B. pseudomallei identification in Vitek 2 and potentially other automated identification systems is regionally dependent

    The Grizzly, February 20, 1996

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    Talk Show Trouble • Major Fair 1996 • J.D. Salinger: A Grizzly Staffer!; The Skipped Diploma • Boxer Tommy Morrison HIV-Positive • Swedish Vocal Ensemble to Perform • Meet the Candidates: A Largely Biased Commentary • Take it Back, Captain Jack? • Blatant Generalizations • You Bet Your Life • Confessions of a Computer Dork • To Bus or Not to Bus • Vicki Abt Revisited • Free Speech, Abortion, and Presidential Politics • Valentine\u27s Spectacular Brings Elegant Dining to Zack\u27s • WVOU: State of the Nation • Airband Proceeds to Help Student Ryan Auch • Guys Come Up Short in Muhlenberg • Lady Bears Get Crushed by Muhlenberg • Bears Place Four at Eastern Regionalshttps://digitalcommons.ursinus.edu/grizzlynews/1375/thumbnail.jp
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