180 research outputs found

    Kinematics at the intersection of the Garlock and Death Valley fault zones, California: Integration of TM data and field studies

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    The Garlock and Death Valley fault zones in SE California are two active strike-slip faults coming together on the east side of the Avawatz Mtns. The kinematics of this intersection, and the possible continuation of either fault zone, are being investigated using a combination of field mapping, and processing and interpretation of remotely sensed image data. Regional and local relationships are derivable from Thematic Mapper data (30 m resolution), including discrimination and relative age dating of alluvial fans, bedrock mapping, and fault mapping. Aircraft data provide higher spatial resolution over more limited areas. Hypotheses being considered are: (1) the Garlock fault extends east of the intersection; (2) the Garlock fault terminates at the intersection and the Death Valley fault continues southeastward; and (3) the Garlock fault has been offset right laterally by the Death Valley fault which continues to the southeast. Preliminary work indicates that the first hypothesis is invalid. From kinematic considerations, image analysis, and field work the third hypothesis is favored. The projected continuation of the Death Valley zone defines the boundary between the Mojave crustal block and the Basin and Range block

    Sophomore Recital

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    Contemporary particle-in-cell approach to laser-plasma modelling

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    Particle-in-cell (PIC) methods have a long history in the study of laser-plasma interactions. Early electromagnetic codes used the Yee staggered grid for field variables combined with a leapfrog EM-field update and the Boris algorithm for particle pushing. The general properties of such schemes are well documented. Modern PIC codes tend to add to these high-order shape functions for particles, Poisson preserving field updates, collisions, ionisation, a hybrid scheme for solid density and high-field QED effects. In addition to these physics packages, the increase in computing power now allows simulations with real mass ratios, full 3D dynamics and multi-speckle interaction. This paper presents a review of the core algorithms used in current laser-plasma specific PIC codes. Also reported are estimates of self-heating rates, convergence of collisional routines and test of ionisation models which are not readily available elsewhere. Having reviewed the status of PIC algorithms we present a summary of recent applications of such codes in laser-plasma physics, concentrating on SRS, short-pulse laser-solid interactions, fast-electron transport, and QED effects

    College Student Mental Health and Wellbeing Prior to and during the COVID-19 Pandemic

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    Student mental health was a growing concern globally prior to the onset of the COVID-19 pandemic. The aim of this study was to assess the impact of the pandemic and associated restrictions on the psychological wellbeing of college students. Baseline data were collected pre-pandemic in September 2019 among students attending a university in Northern Ireland and an Institute of Technology in the Republic of Ireland. Surveys were also conducted with this cohort during the pandemic, at the start of the academic years 2020 and 2021 (499 students fully completed all three waves). A follow-up survey was conducted at the end of their third year, in summer 2022 (n = 229). High levels of mental health problems were already present among students commencing college. The subsequent pandemic had a very negative impact on student’s academic experience and other aspects of life. Rates of depression (PHQ-9) increased significantly from the onset of the pandemic and remained high. Anxiety (GAD-7) initially decreased but then escalated at the end of college. The study highlights the importance of early intervention and makes recommendations for addressing the needs of students during times of stress. Additional supports may be required to deal with the long-lasting impact of the pandemic

    Influenza Vaccine Effectiveness against Hospitalisation with Confirmed Influenza in the 2010-11 Seasons: A Test-negative Observational Study

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    Immunisation programs are designed to reduce serious morbidity and mortality from influenza, but most evidence supporting the effectiveness of this intervention has focused on disease in the community or in primary care settings. We aimed to examine the effectiveness of influenza vaccination against hospitalisation with confirmed influenza. We compared influenza vaccination status in patients hospitalised with PCR-confirmed influenza with patients hospitalised with influenza-negative respiratory infections in an Australian sentinel surveillance system. Vaccine effectiveness was estimated from the odds ratio of vaccination in cases and controls. We performed both simple multivariate regression and a stratified analysis based on propensity score of vaccination. Vaccination status was ascertained in 333 of 598 patients with confirmed influenza and 785 of 1384 test-negative patients. Overall estimated crude vaccine effectiveness was 57% (41%, 68%). After adjusting for age, chronic comorbidities and pregnancy status, the estimated vaccine effectiveness was 37% (95% CI: 12%, 55%). In an analysis accounting for a propensity score for vaccination, the estimated vaccine effectiveness was 48.3% (95% CI: 30.0, 61.8%). Influenza vaccination was moderately protective against hospitalisation with influenza in the 2010 and 2011 seasons

    Investigating the Direct Meltwater Effect in Terrestrial Oxygenâ Isotope Paleoclimate Records Using an Isotopeâ Enabled Earth System Model

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    Variations in terrestrial oxygenâ isotope reconstructions from ice cores and speleothems have been primarily attributed to climatic changes of surface air temperature, precipitation amount, or atmospheric circulation. Here we demonstrate with the fully coupled isotopeâ enabled Community Earth System Model an additional process contributing to the oxygenâ isotope variations during glacial meltwater events. This process, termed â the direct meltwater effect,â involves propagating large amounts of isotopically depleted meltwater throughout the hydrological cycle and is independent of climatic changes. We find that the direct meltwater effect can make up 15â 35% of the δ18O signals in precipitation over Greenland and eastern Brazil for large freshwater forcings (0.25â 0.50 sverdrup (106 m3/s)). Model simulations further demonstrate that the direct meltwater effect increases with the magnitude and duration of the freshwater forcing and is sensitive to both the location and shape of the meltwater. These new modeling results have important implications for past climate interpretations of δ18O.Key PointsA portion of the δ18O signal in landâ based paleoclimate proxies can be attributed to the direct meltwater effect instead of climatic changesThe direct meltwater effect can make up 15â 35% of the δ18O signals in precipitation in Greenland and eastern Brazil for large meltwater eventsThe direct meltwater effect increases with the magnitude and duration of the freshwater forcing and is sensitive to location and shape dependentPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141374/1/grl56782_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141374/2/grl56782-sup-0001-Supporting_Information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141374/3/grl56782.pd

    Discrete Roles for Impulsivity and Compulsivity in Gambling Disorder

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    Background and Objective: Complex associations between gambling disorder (GD) and impulsivity have been identified. However, little is known regarding how compulsivity associates with different impulsivity domains in GD. In this study, we examined associations between self-reported and behavioral measures of impulsivity-assessed through the Barratt Impulsiveness Scale (BIS-11) and the Experiential Discounting Task (EDT), respectively- and compulsivity-measured using the Padua Inventory and the Wisconsin Card Sorting Test (WCST), respectively-, in an adult sample with GD (N = 132, 94 men and 38 women, ages ranging from 18 to 69 years). GD severity was assessed using the South Oaks Gambling Screen. Methods: Structural Equation Modeling was used to examine relationships between impulsivity and compulsivity measures, age, and GD severity. Results: BIS-11 non-planning and BIS-11 total scores positively correlated with GD severity. The standardized coefficients for the SEM showed direct positive contributions of BIS-11 non-planning, Padua and EDT scores to GD severity. Only participants' ages directly contributed to WCST perseverative errors, and no direct or indirect effects were found with respect to GD severity. Conclusion: The findings suggest that specific aspects of impulsivity and compulsivity contribute to GD severity. Interventions specifically targeting domains that are most relevant to GD severity may improve treatment outcomes

    A study protocol for a randomised controlled feasibility trial of an intervention to increase activity and reduce sedentary behaviour in people with severe mental illness: Walking fOR Health (WORtH) Study

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    Abstract Background People with severe mental illness (SMI) are less physically active and more sedentary than healthy controls, contributing to poorer physical health outcomes in this population. There is a need to understand the feasibility and acceptability, and explore the effective components, of health behaviour change interventions targeting physical activity and sedentary behaviour in this population in rural and semi-rural settings. Methods This 13-week randomised controlled feasibility trial compares the Walking fOR Health (WORtH) multi-component behaviour change intervention, which includes education, goal-setting and self-monitoring, with a one-off education session. It aims to recruit 60 inactive adults with SMI via three community mental health teams in Ireland and Northern Ireland. Primary outcomes are related to feasibility and acceptability, including recruitment, retention and adherence rates, adverse events and qualitative feedback from participants and clinicians. Secondary outcome measures include self-reported and accelerometer-measured physical activity and sedentary behaviour, anthropometry measures, physical function and mental wellbeing. A mixed-methods process evaluation will be undertaken. This study protocol outlines changes to the study in response to the COVID-19 pandemic. Discussion This study will address the challenges and implications of remote delivery of the WORtH intervention due to the COVID-19 pandemic and inform the design of a future definitive randomised controlled trial if it is shown to be feasible. Trial registration The trial was registered on clinicaltrials.gov ( NCT04134871 ) on 22 October 2019
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