14,440 research outputs found

    Collide and Conquer: Constraints on Simplified Dark Matter Models using Mono-X Collider Searches

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    The use of simplified models as a tool for interpreting dark matter collider searches has become increasingly prevalent, and while early Run II results are beginning to appear, we look to see what further information can be extracted from the Run I dataset. We consider three `standard' simplified models that couple quarks to fermionic singlet dark matter: an ss-channel vector mediator with vector or axial-vector couplings, and a tt-channel scalar mediator. Upper limits on the couplings are calculated and compared across three alternate channels, namely mono-jet, mono-ZZ (leptonic) and mono-W/ZW/Z (hadronic). The strongest limits are observed in the mono-jet channel, however the computational simplicity and absence of significant tt-channel model width effects in the mono-boson channels make these a straightforward and competitive alternative. We also include a comparison with relic density and direct detection constraints.Comment: 32 pages, 8 figures; v2: minor changes, conclusion unchanged, matches published versio

    Towards validation of a new computerised test of goal neglect: preliminary evidence from clinical and neuroimaging pilot studies

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    Objective: Goal neglect is a significant problem following brain injury, and is a target for rehabilitation. It is not yet known how neural activation might change to reflect rehabilitation gains. We developed a computerised multiple elements test (CMET), suitable for use in neuroimaging paradigms. Design: Pilot correlational study and event-related fMRI study. Methods: In Study 1, 18 adults with acquired brain injury were assessed using the CMET, other tests of goal neglect (Hotel Test; Modified Six Elements Test) and tests of reasoning. In Study 2, 12 healthy adults underwent fMRI, during which the CMET was administered under two conditions: self-generated switching and experimenter-prompted switching. Results: Among the clinical sample, CMET performance was positively correlated with both the Hotel Test (r = 0.675, p = 0.003) and the Modified Six Elements Test (r = 0.568, p = 0.014), but not with other clinical or demographic measures. In the healthy sample, fMRI demonstrated significant activation in rostro-lateral prefrontal cortex in the self-generated condition compared with the prompted condition (peak 40, 44, 4; ZE = 4.25, p(FWEcorr) = 0.026). Conclusions: These pilot studies provide preliminary evidence towards the validation of the CMET as a measure of goal neglect. Future studies will aim to further establish its psychometric properties, and determine optimum pre- and post-rehabilitation fMRI paradigms

    Application of High-precision Timing Systems to Distributed Survey Systems

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    In any hydrographic survey system that consists of more than one computer, one of the most difficult integration problems is to ensure that all components maintain a coherent sense of time. Since virtually all modern survey systems are of this type, timekeeping and synchronized timestamping of data as it is created is of significant concern. This paper describes a method for resolving this problem based on the IEEE 1588 Precise Time Protocol (PTP) implemented by hardware devices, layered with some custom software called the Software Grandmaster (SWGM) algorithm. This combination of hardware and software maintains a coherent sense of time between multiple ethernet-connected computers, on the order of 100 ns (rms) in the best case, of the timebase established by the local GPS-receiver clock. We illustrate the performance of this techniques in a practical survey system using a Reson 7P sonar processor connected to a Reson 7125 Multibeam Echosounder (MBES), integrated with an Applanix POS/MV 320 V4 and a conventional data capture computer. Using the timing capabilities of the PTP hardware implementations, we show that the timepieces achieve mean (hardware based) synchronization and timestamping within 100-150 ns (rms), and that the data created at the Reson 7P without hardware timestamps has a latency variability of 28 µs (rms) due to software constraints within the capture system. This compares to 288 ms (rms) using Reson’s standard hybrid hardware/software solution, and 13.6 ms (rms) using a conventional single-oscillator timestamping model

    Cryogenic propellant venting under low pressure conditions final report

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    Cryogenic propellant venting under low pressure conditions - heat-transfer coefficients for two- phase, single component, solid-gas mixture flow in short, vertical tub

    Effectiveness of anonymised information sharing and use in health service, police, and local government partnership for preventing violence related injury: experimental study and time series analysis

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    Objective: To evaluate the effectiveness of anonymised information sharing to prevent injury related to violence. Design: Experimental study and time series analysis of a prototype community partnership between the health service, police, and local government partners designed to prevent violence. Setting: Cardiff, Wales, and 14 comparison cities designated "most similar" by the Home Office in England and Wales. Intervention After a 33 month development period, anonymised data relevant to violence prevention (precise violence location, time, days, and weapons) from patients attending emergency departments in Cardiff and reporting injury from violence were shared over 51 months with police and local authority partners and used to target resources for violence prevention. Main outcome measures: Health service records of hospital admissions related to violence and police records of woundings and less serious assaults in Cardiff and other cities after adjustment for potential confounders. Results: Information sharing and use were associated with a substantial and significant reduction in hospital admissions related to violence. In the intervention city (Cardiff) rates fell from seven to five a month per 100 000 population compared with an increase from five to eight in comparison cities (adjusted incidence rate ratio 0.58, 95% confidence interval 0.49 to 0.69). Average rate of woundings recorded by the police changed from 54 to 82 a month per 100 000 population in Cardiff compared with an increase from 54 to 114 in comparison cities (adjusted incidence rate ratio 0.68, 0.61 to 0.75). There was a significant increase in less serious assaults recorded by the police, from 15 to 20 a month per 100 000 population in Cardiff compared with a decrease from 42 to 33 in comparison cities (adjusted incidence rate ratio 1.38, 1.13 to 1.70). Conclusion: An information sharing partnership between health services, police, and local government in Cardiff, Wales, altered policing and other strategies to prevent violence based on information collected from patients treated in emergency departments after injury sustained in violence. This intervention led to a significant reduction in violent injury and was associated with an increase in police recording of minor assaults in Cardiff compared with similar cities in England and Wales where this intervention was not implemented

    The short-term effects of management changes on watertable position and nutrients in shallow groundwater in a harvested peatland forest

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    This work was funded by the Department of Agriculture, Fisheries and Food and the Environmental Protection Agency under the STRIVE program 2007 – 2013.peer-reviewedManagement changes such as drainage, fertilisation, afforestation and harvesting (clearfelling) of forested peatlands influence watertable (WT) position and groundwater concentrations of nutrients. This study investigated the impact of clearfelling of a peatland forest on WT and nutrient concentrations. Three areas were examined: (1) a regenerated riparian peatland buffer (RB) clearfelled four years prior to the present study (2) a recently clearfelled coniferous forest (CF) and (3) a standing, mature coniferous forest (SF), on which no harvesting took place. The WT remained consistently below 0.3 m during the pre-clearfelling period. Results showed there was an almost immediate rise in the WT after clearfelling and a rise to 0.15 m below ground level (bgl) within 10 months of clearfelling. Clearfelling of the forest increased dissolved reactive phosphorus concentrations (from an average of 28–230 μg L−1) in the shallow groundwater, likely caused by leaching from degrading brash mats.Environmental Protection AgencyDepartment of Agriculture, Food and the Marin

    Staphylococcus aureus bacteraemia in children: a formidable foe

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    Staphylococcus aureus remains one of the most common causes of bacteraemia in children. In order to evade and overcome the immune responses of its host and any antimicrobial therapies aimed at destroying it, this organism, through various mechanisms, continues to evolve. Staphylococcus aureus bacteraemia is a systemic disease; and, multiple organ involvement should be assessed and appropriately managed. This is especially important for the anaesthetist who will be administering general anaesthesia to children presenting for surgical source control.Keywords: bacteraemia, children, pneumonia, septic arthritis, staphylococcus aureu

    Matrix Transfer Function Design for Flexible Structures: An Application

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    The application of matrix transfer function design techniques to the problem of disturbance rejection on a flexible space structure is demonstrated. The design approach is based on parameterizing a class of stabilizing compensators for the plant and formulating the design specifications as a constrained minimization problem in terms of these parameters. The solution yields a matrix transfer function representation of the compensator. A state space realization of the compensator is constructed to investigate performance and stability on the nominal and perturbed models. The application is made to the ACOSSA (Active Control of Space Structures) optical structure
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