1,620 research outputs found

    Responding to Natural Hazards: The Effects of Disaster on Residential Location Decisions and Health Outcomes

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    Exposure to natural hazards is rapidly increasing due to growing populations within floodplains and along hazard-prone coastlines. This trend, coupled with potential increases in the frequency and intensity of extreme weather events from climate change, underscores the importance of disaster research and continued advancements in hazard risk mitigation. This dissertation conducts analyses regarding the effects of natural hazards on residential location choice, county migration rates, mental health status, and displacement. The results have practical implications for disaster risk management. Chapter 2 estimates household willingness-to-pay to live in lower hazard-risk areas. A model of residential location choice is developed in which households select the location that maximizes expected utility. Empirical estimates are obtained using a two-stage estimation process that exploits spatial variation in labor markets, housing markets, and environmental amenities across U.S. metropolitan statistical areas. Results indicate an annual willingness-to-pay of $275 per household for a marginal reduction in the expected number of earthquake, hurricane, and flood events per 1000 years. Chapter 3 estimates the relationship between county-level net in-migration rates and the expected frequency of hazard events. Empirical estimation is complicated by the presence of spatial dependency and heterogeneity. These issues are addressed using spatial simultaneous autoregressive estimation and geographically weighted regression. Results show that net in-migration rates are negatively correlated with expected frequency. Moreover, the effects of hazard risk are strongest in the Southern U.S.; a region susceptible to increased hazard intensity from climate change. Chapter 4 contains two separate analyses regarding the wellbeing of individuals affected by Hurricanes Katrina and Rita. The first analysis evaluates the effect of post-disaster stress and vulnerability on long-term mental health. Results show that the likelihood of being diagnosed with an adverse mental health condition increases with stress and vulnerability levels. The second analysis evaluates the determinants of displacement and the duration of displacement. Results show that housing damage is the most important predictor of displacement and displacement duration. Social support has a positive impact on displacement but a negative impact on the displacement duration, implying that social networks provide accommodations during hazard events as well as assistance in returning home

    An assessment of the mantle and slab components in the magmas of an oceanic arc volcano: Raoul Volcano, Kermadec arc

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    Raoul Volcano occupies a simple oceanic subduction setting in the northern part of the Kermadec arc on the Pacific–Australian convergent plate boundary. The primary inputs to the magmatic system that feeds the volcano are a subduction component derived from the subducting old Pacific oceanic lithosphere and its veneer of pelagic sediment, and the overlying peridotitic mantle wedge. Conservative trace elements that are very incompatible during mantle melting are relatively depleted in Raoul lavas indicating a source that has been depleted during an earlier melting event. Major element co-variations indicate magma genesis by 25% near fractional melting of a mantle source that is weakly depleted (2% melt extraction) relative to a fertile MORB source. An important influence on the composition of the mantle component is progressive melt extraction coupled with minimal advection of fresh material into the sub-arc zone followed by melt extraction from a melting column beneath the spreading centre of an adjacent back arc basin. High field strength element and rare earth element systematics indicate involvement of a subduction-related component of constant composition. Two fluid components can be distinguished, one enriched in large ion lithophile elements inferred to be an aqueous fluid that is continuously added to the ascending melt column and the other a less mobile fluid that transfers Th. A homogeneous subduction-related component of constant composition and magnitude arises if the slab-derived flux migrates from the slab–mantle interface to the sub-arc melting column by repeated episodes of amphibole formation and decomposition its composition is then governed by the distribution coefficients of pyroxene and its magnitude by the degree of amphibole saturation of mantle peridotite. The results from Raoul Volcano are comparable to those from other oceanic subduction-related arcs such as South Sandwich and Marianas suggesting that this is a general model for oceanic arcs

    A new sighting study for the fixed concentration procedure to allow for gender differences

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    The fixed concentration procedure (FCP) has been proposed as an alternative to the median lethal concentration (LC50) test (organisation for economic co-operation and development (OECD) test guideline [TG] 403) for the assessment of acute inhalation toxicity. The FCP tests animals of a single gender (usually females) at a number of fixed concentration levels in a sequential fashion. It begins with a sighting study that precedes the main FCP study and is used to determine the main study starting concentration. In this paper, we propose a modification to the sighting study and suggest that it should be conducted using both male and female animals, rather than just animals of a single gender. Statistical analysis demonstrates that, when females are more sensitive, the new procedure is likely to give the same classification as the original FCP, whereas, if males are more sensitive, the new procedure is much less likely to lead to incorrect classification into a less toxic category. If there is no difference in the LC50 for females and males, the new procedure is slightly more likely to classify into a more stringent class than the original FCP. Overall, these results show that the revised sighting study ensures gender differences in sensitivity do not significantly impact on the performance of the FCP, supporting its use as an alternative test method for assessing acute inhalation toxicity

    Developing a Carbon Management Plan for the Royal Botanic Garden Edinburgh

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    Royal Botanic Garden Edinburgh joined the Carbon Management-Lite Programme run by the Carbon Trust in November 2009. This paper provides details of the programme and the process of writing a Carbon Management Plan

    On the fragmentation boundary in magnetized self-gravitating discs

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    DHF and IAB gratefully acknowledge support from the ECOGAL project, grant agreement 291227, funded by the European Research Council under ER-2011-ADG. DJP gratefully acknowledges funding via grants DP130102078 and FT130100034 and via Future Fellowship FT130100034 from the Australian Research Council.We investigate the role of magnetic fields in the fragmentation of self-gravitating discs using 3D global ideal magnetohydrodynamic simulations performed with the PHANTOM smoothed particle hydrodynamics code. For initially toroidal fields, we find two regimes. In the first, where the cooling time is greater than five times the dynamical time, magnetic fields reduce spiral density wave amplitudes, which in turn suppresses fragmentation. This is the case even if the magnetic pressure is only a 10th of the thermal pressure. The second regime occurs when the cooling time is sufficiently short that magnetic fields cannot halt fragmentation.We find that magnetized discs produce more massive fragments, due to both the additional pressure exerted by the magnetic field and the additional angular momentum transport induced by Maxwell stresses. The fragments are confined to a narrower range of initial semimajor axes than those in unmagnetized discs. The orbital eccentricity and inclination distributions of unmagnetized and magnetized disc fragments are similar. Our results suggest that the fragmentation boundary could be at cooling times a factor of 2 lower than predicted by purely hydrodynamical models.Publisher PDFPeer reviewe

    Predicting success in graduate entry medical students undertaking a graduate entry medical program (GEM)

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    Background: Success in undergraduate medical courses in the UK can be predicted by school exit examination (A level) grades. There are no documented predictors of success in UK graduate entry medicine (GEM) courses. This study looks at the examination performance of GEM students to identify factors which may predict success; of particular interest was A level score. Methods: Data was collected for students graduating in 2004, 2005 and 2006, including demographic details (age and gender), details of previous academic achievement (A level total score and prior degree) and examination results at several points during the degree course. Results: Study group comprised 285 students. Statistical analyses identified no significant variables when looking at clinical examinations. Analysis of pass/fail data for written examinations showed no relationship with A level score. However, both percentage data for the final written examination and the analysis of the award of honours showed A level scores of AAB or higher were associated with better performance (p < 0.001). Discussion: A prime objective of introducing GEM programs was to diversify admissions to medical school. In trying to achieve this, medical schools have changed selection criteria. The findings in this study justify this by proving that A level score was not associated with success in either clinical examinations or passing written examinations. Despite this, very high achievements at A level do predict high achievement during medical school. Conclusions: This study shows that selecting graduate medical students with the basic requirement of an upper-second class honours degree is justifiable and does not disadvantage students who may not have achieved high scores in school leaver examinations

    Numerical modelling of the evolution of the boundary layer during a radiation fog event

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    Despite the impact it has on human activity, particularly transport, accurate forecasting of fog remains a major challenge for numerical weather prediction models. The complex interaction between various physical processes, many of which are parametrised and highly sensitive to small changes, is one of the key reasons for poor fog forecasts. One challenge for numerical models is predicting the structure of the boundary layer, which often undergoes a transition from statically stable to weakly unstable during the life cycle of a fog event. The recent local and non‐local fog experiment (LANFEX) has provided a new comprehensive and detailed observational dataset of fog events. Here, a case study has been used as the basis for an investigation of the effect of the humidity of the residual layer and wind speed on the stability of the boundary layer during a fog event. We find a very high sensitivity in the timing of the stability transition during the fog event; for example, a +3% relative humidity perturbation results in a delay of almost 3h, while a 0.45ms−1 10m wind speed perturbation results in a delay of more than 8h

    Dickkopf-3 is upregulated in osteoarthritis and has a chondroprotective role

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    Objective Dickkopf-3 (Dkk3) is a non-canonical member of the Dkk family of Wnt antagonists and its upregulation has been reported in microarray analysis of cartilage from mouse models of osteoarthritis (OA). In this study we assessed Dkk3 expression in human OA cartilage to ascertain its potential role in chondrocyte signaling and cartilage maintenance. Methods Dkk3 expression was analysed in human adult OA cartilage and synovial tissues and during chondrogenesis of ATDC5 and human mesenchymal stem cells. The role of Dkk3 in cartilage maintenance was analysed by incubation of bovine and human cartilage explants with interleukin-1 (IL1) and oncostatin-M (OSM). Dkk3 expression was measured in cartilage following murine hip avulsion. Whether Dkk3 influenced Wnt, TGF and activin cell signaling was assessed in primary human chondrocytes and SW1353 chondrosarcoma cells using RT-qPCR and luminescence assays. Results Increased gene and protein levels of Dkk3 were detected in human OA cartilage, synovial tissue and synovial fluid. DKK3 expression was decreased during chondrogenesis of both ATDC5 cells and humans MSCs. Dkk3 inhibited IL1 and OSM-mediated proteoglycan loss from human and bovine cartilage explants and collagen loss from bovine cartilage explans. Cartilage DKK3 expression was decreased following hip avulsion injury. TGF signaling was enhanced by Dkk3 and Wnt3a and activin signaling were inhibited. Conclusions We provide evidence that Dkk3 is upregulated in OA and may have a protective effect on cartilage integrity by preventing proteoglycan loss and helping to restore OA-relevant signaling pathway activity. Targeting Dkk3 may be a novel approach in the treatment of OA
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