1,194 research outputs found

    Analytical solutions for compartmental models of contaminant transport in enclosed spaces

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    Understanding the transport of hazardous airborne materials within buildings and other enclosed spaces is important for predicting and mitigating the impacts of deliberate terrorist releases of chemical and biological materials. Multizone models provide an approach to modelling the contamination levels in enclosed spaces but in certain cases they can be computationally expensive. Alternative methods are being explored at DSTL that involve the direct solution of the contaminant dynamics equation. The Study Group was asked to identify the limits to this alternative approach and to explore its extension

    "Man" and his "Others"

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    Noncooperative equilibrium solutions for spectrum access in distributed cognitive radio networks

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    The Quality of the Student Experience of Higher Education: an Investigation in Hong Kong

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    This work begins by examining the issue of quality in higher education. No universally agreed definition seems to exist. It is argued that the concept of the quality of higher education can only be expressed in terms of each of the different purposes of a university. The concept of the quality of the teaching and learning dimension of a university's mission is considered. It is then further argued that the quality of this dimension must be connected, in part at least, to the student experience and to students' learning outcomes. Various literatures on quality and quality assurance, students' approaches to learning and student engagement are explored. In order to explore this relationship between quality, the student experience and learning outcomes some empirical research was conducted in Hong Kong to address the following research questions which emerged and were refined through the review of the literature: 'What is the student experience of higher education in Hong Kong like (ie what are its qualities)?' 'How does the student experience affect learning outcomes?' The fieldwork was conducted by means of an adapted version of the North American survey instrument the 'College Students' Experience Questionnaire'. The instrument was adapted using a progressive Focus Group technique. The questionnaire was then administered to a representative sample of (5600) full time undergraduate students in all of the universities in Hong Kong. The results describe the student experience in Hong Kong. By using multiple regression techniques an exploration is made of the association between certain forms of engagement in university activities and learning outcomes. The results of these analyses are reported and the implications discussed. Finally some policy recommendations are made

    Low latency low power bit flipping algorithms for LDPC decoding

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    Using scenarios to test the appropriateness of pharmacist prescribing in asthma management

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    Objective: To explore the potential for community pharmacist prescribing in terms of usefulness, pharmacists' confidence, and appropriateness, in the context of asthma management. Methods: Twenty community pharmacists were recruited using convenience sampling from a group of trained practitioners who had already delivered asthma services. These pharmacists were asked to complete a scenariobased questionnaire (9 scenarios) modelled on information from real patients. Pharmacist interventions were independently reviewed and rated on their appropriateness according to the Respiratory Therapeutic Guidelines (TG) by three expert researchers. Results: In seven of nine scenarios (78%), the most common prescribing intervention made by pharmacists agreed with TG recommendations. Although the prescribing intervention was appropriate in the majority of cases, the execution of such interventions was not in line with guidelines (i.e. dosage or frequency) in the majority of scenarios. Due to this, only 47% (76/162) of the interventions overall were considered appropriate. However, pharmacists were deemed to be often following common clinical practice for asthma prescribing. Therefore 81% (132/162) of prescribing interventions were consistent with clinical practice, which is often not guideline driven, indicating a need for specific training in prescribing according to guidelines. Pharmacists reported that they were confident in making prescribing interventions and that this would be very useful in their management of the patients in the scenarios. Conclusion: Community pharmacists may be able to prescribe asthma medications appropriately to help achieve good outcomes for their patients. However, further training in the guidelines for prescribing are required if pharmacists are to support asthma management in this way

    Isolation and characterization of microsatellite loci from two inbreeding bark beetle species (Coccotrypes)

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    We developed 14 microsatellite markers in Coccotrypes carpophagus and 14 in C. dactyliperda. These loci will be used for studying genetic structure and the level of inbreeding in populations in the Canary Islands and Madeira. As a result of long-term inbreeding, genetic variability is relatively low in these bark beetle species. We found one to five alleles per locus in 29 C. carpophagus and 41 C. dactyliperda from various localities. Eleven of the markers developed for C. carpophagus amplified in C. dactyliperda and seven of the markers developed for C. dactyliperda amplified in C. carpophagus

    Shallow BF2 implants in Xe-bombardment-preamorphized Si: the interaction between Xe and F

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    Si(100) samples, preamorphized to a depth of ~30 nm using 20 keV Xe ions to a nominal fluence of 2×1014 cm-2 were implanted with 1 and 3 keV BF2 ions to fluences of 7×1014 cm-2. Following annealing over a range of temperatures (from 600 to 1130 °C) and times the implant redistribution was investigated using medium-energy ion scattering (MEIS), secondary ion mass spectrometry (SIMS), and energy filtered transmission electron microscopy (EFTEM). MEIS studies showed that for all annealing conditions leading to solid phase epitaxial regrowth, approximately half of the Xe had accumulated at depths of 7 nm for the 1 keV and at 13 nm for the 3 keV BF2 implant. These depths correspond to the end of range of the B and F within the amorphous Si. SIMS showed that in the preamorphized samples, approximately 10% of the F migrates into the bulk and is trapped at the same depths in a ~1:1 ratio to Xe. These observations indicate an interaction between the Xe and F implants and a damage structure that becomes a trapping site. A small fraction of the implanted B is also trapped at this depth. EXTEM micrographs suggest the development of Xe agglomerates at the depths determined by MEIS. The effect is interpreted in terms of the formation of a volume defect structure within the amorphized Si, leading to F stabilized Xe agglomerates or XeF precipitates

    Current noise of a superconducting single electron transistor coupled to a resonator

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    We analyze the current and zero-frequency current noise properties of a superconducting single electron resonator (SSET) coupled to a resonator, focusing on the regime where the SSET is operated in the vicinity of the Josephson quasiparticle resonance. We consider a range of coupling strengths and resonator frequencies to reflect the fact that in practice the system can be tuned to quite a high degree with the resonator formed either by a nanomechanical oscillator or a superconducting stripline fabricated in close proximity to the SSET. For very weak couplings the SSET acts on the resonator like an effective thermal bath. In this regime the current characteristics of the SSET are only weakly modified by the resonator. Using a mean field approach, we show that the current noise is nevertheless very sensitive to the correlations between the resonator and the SSET charge. For stronger couplings, the SSET can drive the resonator into limit cycle states where self-sustained oscillation occurs and we find that regions of well-defined bistability exist. Dynamical transitions into and out of the limit cycle state are marked by strong fluctuations in the resonator energy, but these fluctuations are suppressed within the limit cycle state. We find that the current noise of the SSET is strongly influenced by the fluctuations in the resonator energy and hence should provide a useful indicator of the resonator's dynamics.Comment: Reduced quality figures for arXiv version; v2 minor correction
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