12,511 research outputs found

    Prevalence of disorders recorded in Cavalier King Charles Spaniels attending primary-care veterinary practices in England

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    Concerns have been raised over breed-related health issues in purebred dogs, but reliable prevalence estimates for disorders within specific breeds are sparse. Electronically stored patient health records from primary-care practice are emerging as a useful source of epidemiological data in companion animals. This study used large volumes of health data from UK primary-care practices participating in the VetCompass animal health surveillance project to evaluate in detail the disorders diagnosed in a random selection of over 50% of dogs recorded as Cavalier King Charles Spaniels (CKCSs). Confirmation of breed using available microchip and Kennel Club (KC) registration data was attempted

    Remarks on Causality in Relativistic Quantum Field Theory

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    It is shown that the correlations predicted by relativistic quantum field theory in locally normal states between projections in local von Neumann algebras \cA(V_1),\cA(V_2) associated with spacelike separated spacetime regions V1,V2V_1,V_2 have a (Reichenbachian) common cause located in the union of the backward light cones of V1V_1 and V2V_2. Further comments on causality and independence in quantum field theory are made.Comment: 10 pages, Latex, Quantum Structures 2002 Conference Proceedings submission. Minor revision of the order of definitions on p.

    Effect of variations in the doping profiles on the properties of doped multiple quantum well avalanche photodiodes

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    The purpose of this study is to use both theoretical and experimental evidence to determine the impact of doping imbalance and symmetry on the physical and electrical characteristics of doped multiple quantum well avalanche photodiodes (APD). Theoretical models have been developed to calculate the electric field valence and conduction bands, capacitance-voltage (CV), and carrier concentration versus depletion depth profiles. The models showed a strong correlation between the p- and n-doping balance inside the GaAs wells and the number of depleted stages and breakdown voltage of the APD. A periodic doping imbalance in the wells has been shown to result in a gradual increase (or decrease) in the electric field profile throughout the device which gave rise to partially depleted devices at low bias. The MQW APD structures that we modeled consisted of a 1 micron top p(+)-doped (3 x 10(exp 18) cm(exp -3)) GaAs layer followed by a 1 micron region of alternating layers of GaAs (500 A) and Al(0.42)Ga(0.58)As (500 A), and a 1 micron n(+) back layer (3 x 10(exp 18) cm(exp -3)). The GaAs wells were doped with p-i-n layers placed at the center of each well. The simulation results showed that in an APD with nine doped wells, and where the 50 A p-doped layer is off by 10% (p = 1.65 x 10(exp 18) cm(exp -3), n = 1.5 x 10(exp 18) cm(exp -3)), almost half of the MQW stages were shown to be undepleted at low bias which was a result of a reduction in the electric field near the p(+) cap layer by over 50% from its value in the balanced structure. Experimental CV and IV data on similar MBE grown MQW structures have shown very similar depletion and breakdown characteristics. The models have enabled us to better interpret our experimental data and to determine both the extent of the doping imbalances in the devices as well as the overall p- or n-type doping characteristics of the structures

    Probabilistic computer model of optimal runway turnoffs

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    Landing delays are currently a problem at major air carrier airports and many forecasters agree that airport congestion will get worse by the end of the century. It is anticipated that some types of delays can be reduced by an efficient optimal runway exist system allowing increased approach volumes necessary at congested airports. A computerized Probabilistic Runway Turnoff Model which locates exits and defines path geometry for a selected maximum occupancy time appropriate for each TERPS aircraft category is defined. The model includes an algorithm for lateral ride comfort limits

    Knowledge, attitudes and practices of health care professionals towards adverse drug reaction reporting in public sector primary health care facilities in a South African district

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    Purpose: Adverse drug reactions (ADRs) have an appreciable impact on patients’ health. Little is known however about ADR reporting in ambulatory care environments especially in low- and middle-income countries. Consequently, our aim was to determine knowledge, attitudes and practices (KAP) among health care professionals (HCPs) towards ADR reporting in primary health care (PHC) facilities in South Africa. The findings will be used to direct future activities. Methods: Descriptive, cross-sectional design using quantitative methodology among 8 public sector community health care centres and 40 PHC clinics in the Tshwane Health District, Gauteng Province. A self-administered questionnaire was distributed to 218 HCPs, including all key groups. Results: A total of 200 responses were received (91.7%). Although an appropriate attitude towards ADR reporting existed, the actual frequency of ADR reporting was low (16.0%). Of the respondents, 60.5% did not know how to report, where to report or when to report an ADR and 51.5% said the level of their clinical knowledge made it difficult to decide whether or not an ADR had occurred. Over 97.5% stated they should be reporting ADRs with 89% feeling that ADR reporting is a professional obligation and over 70% that ADR reporting should be compulsory. When results were combined, the overall mean score in terms of positive or preferred practices for ADR reporting was 24.6% with pharmacists having the highest scores. Conclusion: Under-reporting of ADRs with gaps in KAP was evident. There is a serious and urgent need for education and training of HCPs on ADR reporting in South Africa

    The Diagnostic Potential of Transition Region Lines under-going Transient Ionization in Dynamic Events

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    We discuss the diagnostic potential of high cadence ultraviolet spectral data when transient ionization is considered. For this we use high cadence UV spectra taken during the impulsive phase of a solar flares (observed with instruments on-board the Solar Maximum Mission) which showed excellent correspondence with hard X-ray pulses. The ionization fraction of the transition region ion O V and in particular the contribution function for the O V 1371A line are computed within the Atomic Data and Analysis Structure, which is a collection of fundamental and derived atomic data and codes which manipulate them. Due to transient ionization, the O V 1371A line is enhanced in the first fraction of a second with the peak in the line contribution function occurring initially at a higher electron temperature than in ionization equilibrium. The rise time and enhancement factor depend mostly on the electron density. The fractional increase in the O V 1371A emissivity due to transient ionization can reach a factor of 2--4 and can explain the fast response in the line flux of transition regions ions during the impulsive phase of flares solely as a result of transient ionization. This technique can be used to diagnostic the electron temperature and density of solar flares observed with the forth-coming Interface Region Imaging Spectrograph.Comment: 18 pages, 6 figure

    A structural evaluation of the tungsten isotopes via thermal neutron capture

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    Total radiative thermal neutron-capture γ\gamma-ray cross sections for the 182,183,184,186^{182,183,184,186}W isotopes were measured using guided neutron beams from the Budapest Research Reactor to induce prompt and delayed γ\gamma rays from elemental and isotopically-enriched tungsten targets. These cross sections were determined from the sum of measured γ\gamma-ray cross sections feeding the ground state from low-lying levels below a cutoff energy, Ecrit_{\rm crit}, where the level scheme is completely known, and continuum γ\gamma rays from levels above Ecrit_{\rm crit}, calculated using the Monte Carlo statistical-decay code DICEBOX. The new cross sections determined in this work for the tungsten nuclides are: σ0(182W)=20.5(14)\sigma_{0}(^{182}{\rm W}) = 20.5(14) b and σ11/2+(183Wm,5.2s)=0.177(18)\sigma_{11/2^{+}}(^{183}{\rm W}^{m}, 5.2 {\rm s}) = 0.177(18) b; σ0(183W)=9.37(38)\sigma_{0}(^{183}{\rm W}) = 9.37(38) b and σ5(184Wm,8.33μs)=0.0247(55)\sigma_{5^{-}}(^{184}{\rm W}^{m}, 8.33 \mu{\rm s}) = 0.0247(55) b; σ0(184W)=1.43(10)\sigma_{0}(^{184}{\rm W}) = 1.43(10) b and σ11/2+(185Wm,1.67min)=0.0062(16)\sigma_{11/2^{+}}(^{185}{\rm W}^{m}, 1.67 {\rm min}) = 0.0062(16) b; and, σ0(186W)=33.33(62)\sigma_{0}(^{186}{\rm W}) = 33.33(62) b and σ9/2+(187Wm,1.38μs)=0.400(16)\sigma_{9/2^{+}}(^{187}{\rm W}^{m}, 1.38 \mu{\rm s}) = 0.400(16) b. These results are consistent with earlier measurements in the literature. The 186^{186}W cross section was also independently confirmed from an activation measurement, following the decay of 187^{187}W, yielding values for σ0(186W)\sigma_{0}(^{186}{\rm W}) that are consistent with our prompt γ\gamma-ray measurement. The cross-section measurements were found to be insensitive to choice of level density or photon strength model, and only weakly dependent on Ecrit_{\rm crit}. Total radiative-capture widths calculated with DICEBOX showed much greater model dependence, however, the recommended values could be reproduced with selected model choices. The decay schemes for all tungsten isotopes were improved in these analyses.Comment: 25 pages, 15 figures, 15 table
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