680 research outputs found

    Validation of an ensemble modelling system for climate projections for the northwest European shelf seas

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    The aim of this study was to evaluate the performance of a modelling system used to represent the northwest European shelf seas. Variants of the coupled atmosphere–ocean global climate model, HadCM3, were run under conditions of historically varying concentrations of greenhouse gases and other radiatively active constituents. The atmospheric simulation for the shelf sea region and its surrounds was downscaled to finer spatial scales using a regional climate model (HadRM3); these simulations were then used to drive a river routing scheme (TRIP). Together, these provide the atmospheric, oceanic and riverine boundary conditions to drive the shelf seas model POLCOMS. Additionally, a shelf seas simulation was driven by the ERA-40 reanalysis in place of HadCM3. We compared the modelling systems output against a sea surface temperature satellite analysis product, a quality controlled ocean profile dataset and values of volume transport through particular ocean sections from the literature. In addition to assessing model drift with a pre-industrial control simulation the modelling system was evaluated against observations and the reanalysis driven simulation. We concluded that the modelling system provided an excellent (good) representation of the spatial patterns of temperature (salinity). It provided a good representation of the mean temperature climate, and a sufficient representation of the mean salinity and water column structure climate. The representation of the interannual variability was sufficient, while the overall shelf-wide circulation was qualitatively good. From this wide range of metrics we judged the modelling system fit for the purpose of providing centennial climate projections for the northwest European shelf seas

    Assessment of Criticality Safety for Cylindrical Containers to be Used In the Processing of Spent Fuel

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    The UREX process separates uranium from transuranic wastes (TRU) and fission products (FP). Nuclear reactors require fissile isotopes that will absorb neutrons and break apart into smaller nuclei while releasing a large amount of energy as well as multiple neutrons. Fissile isotopes in spent fuel include not only 235U, but also 239Pu, 241Pu, and several isotopes of americium (Am) and curium (Cm). TRU contains the actinides with atomic numbers greater than that of uranium. This includes Pu, Np, Am, and Cm. When TRU is separated from uranium, the TRU still poses a significant risk of sustaining a chain reaction. This is quantified through the effective neutron multiplication factor, keff. To prevent TRU from becoming critical (sustaining a chain reaction), keff must be maintained at a value of less than 1. The presence of neutron poisons (Sm, Xe, B, Hf, Cd, etc.) will decrease keff. Neutron poisons are found in fission products. The presence of neutron moderators (H, C, Be) or materials that reflect neutrons will enhance keff. To assess keff, Monte Carlo simulation codes are used. The concentration of TRU, process salts, and fission products along with the geometry of the mixture and surrounding reflective material are inputs to these codes

    Neural representation of geometry and surface properties in object and scene perception

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    Multiple cortical regions are crucial for perceiving the visual world, yet the processes shaping representations in these regions are unclear. To address this issue, we must elucidate how perceptual features shape representations of the environment. Here, we explore how the weighting of different visual features affects neural representations of objects and scenes, focusing on the scene-selective parahippocampal place area (PPA), but additionally including the retrosplenial complex (RSC), occipital place area (OPA), lateral occipital (LO) area, fusiform face area (FFA) and occipital face area (OFA). Across three experiments, we examined functional magnetic resonance imaging (fMRI) activity while human observers viewed scenes and objects that varied in geometry (shape/layout) and surface properties (texture/material). Interestingly, we found equal sensitivity in the PPA for these properties within a scene, revealing that spatial-selectivity alone does not drive activation within this cortical region. We also observed sensitivity to object texture in PPA, but not to the same degree as scene texture, and representations in PPA varied when objects were placed within scenes. We conclude that PPA may process surface properties in a domain-specific manner, and that the processing of scene texture and geometry is equally-weighted in PPA and may be mediated by similar underlying neuronal mechanisms

    Deconstructing Anesthesia Handoffs During Simulated Intraoperative Anesthesia Care

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    Anesthesia patient handoffs are a vulnerable time for patient care and handoffs occur frequently during anesthesia care. Communication failures contribute to patient harm during anesthesia patient handoffs. The Joint Commission has recognized the potential for communication failure during patient handoffs and has recommended processes to improve handoff safety. Handoffs are made more difficult by latent conditions such as time constraints, pressure and distractions, which often result in incomplete or inaccurate handoff reports. This nonexperimental, correlation study identified the latent conditions that occur during the handoff process and their relationship to the quality of the handoff. This research shows an inverse relationship between latent conditions and anesthesia patient handoff scores. The number of latent conditions and the types of latent conditions affected handoff scores. Handoffs that were not interactive or handoffs with unsafe timing predictably resulted in poor handoff communication. Clinicians must acknowledge that handoffs are a high-risk event that can result in patient harm. Clear and effective communication is key to safe, quality care and this includes being aware of and minimizing the impact of latent conditions during the anesthesia patient handoff
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