735 research outputs found

    An instrument to measure atmospheric pressure fluctuations above surface gravity waves

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    This paper describes an instrument which has been used successfully at a field site in the Bight of Abaco, Bahamas, to monitor the atmospheric pressure field above surface gravity waves in the frequency range .5 to 5. rad/s. The atmospheric pressure is sampled at fixed elevations with a cone-shaped probe having a pressure coefficient of less than .02 magnitude for angles of attack less than 15°; the probe is mounted on a vane to minimize horizontal angles of attack. The pressure signal is conducted to a subsurface transducer through a mercury-sealed bearing. Overall system noise is estimated to be of order .5 µbars and is largely wave-incoherent

    Laboratory-based efficacy evaluation of; Bacillus thuringiensis; var. israelensis and temephos larvicides against larvae of; Anopheles stephensi; in Ethiopia

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    BACKGROUND: Malaria, transmitted by the bite of infective female Anopheles mosquitoes, remains a global public health problem. The presence of an invasive Anopheles stephensi, capable of transmitting Plasmodium vivax and Plasmodium falciparum parasites was first reported in Ethiopia in 2016. The ecology of An. stephensi is different from that of Anopheles arabiensis, the primary Ethiopian malaria vector, and this suggests that alternative control strategies may be necessary. Larviciding may be an effective alternative strategy, but there is limited information on the susceptibility of Ethiopian An. stephensi to common larvicides. This study aimed to evaluate the efficacy of temephos and Bacillus thuringiensis var. israelensis (Bti) larvicides against larvae of invasive An. stephensi. METHODS: The diagnostic doses of two larvicides, temephos (0.25 ml/l) and Bti (0.05 mg/l) were tested in the laboratory against the immature stages (late third to early fourth stages larvae) of An. stephensi collected from the field and reared in a bio-secure insectary. Larvae were collected from two sites (Haro Adi and Awash Subuh Kilo). For each site, three hundred larvae were tested against each insecticide (as well as an untreated control), in batches of 25. The data from all replicates were pooled and descriptive statistics prepared. RESULTS: The mortality of larvae exposed to temephos was 100% for both sites. Mortality to Bti was 99.7% at Awash and 100% at Haro Adi site. CONCLUSIONS: Larvae of An. stephensi are susceptible to temephos and Bti larvicides suggesting that larviciding with these insecticides through vector control programmes may be effective against An. stephensi in these localities

    Grey and white matter correlates of recent and remote autobiographical memory retrieval:Insights from the dementias

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    The capacity to remember self-referential past events relies on the integrity of a distributed neural network. Controversy exists, however, regarding the involvement of specific brain structures for the retrieval of recently experienced versus more distant events. Here, we explored how characteristic patterns of atrophy in neurodegenerative disorders differentially disrupt remote versus recent autobiographical memory. Eleven behavioural-variant frontotemporal dementia, 10 semantic dementia, 15 Alzheimer's disease patients and 14 healthy older Controls completed the Autobiographical Interview. All patient groups displayed significant remote memory impairments relative to Controls. Similarly, recent period retrieval was significantly compromised in behavioural-variant frontotemporal dementia and Alzheimer's disease, yet semantic dementia patients scored in line with Controls. Voxel-based morphometry and diffusion tensor imaging analyses, for all participants combined, were conducted to investigate grey and white matter correlates of remote and recent autobiographical memory retrieval. Neural correlates common to both recent and remote time periods were identified, including the hippocampus, medial prefrontal, and frontopolar cortices, and the forceps minor and left hippocampal portion of the cingulum bundle. Regions exclusively implicated in each time period were also identified. The integrity of the anterior temporal cortices was related to the retrieval of remote memories, whereas the posterior cingulate cortex emerged as a structure significantly associated with recent autobiographical memory retrieval. This study represents the first investigation of the grey and white matter correlates of remote and recent autobiographical memory retrieval in neurodegenerative disorders. Our findings demonstrate the importance of core brain structures, including the medial prefrontal cortex and hippocampus, irrespective of time period, and point towards the contribution of discrete regions in mediating successful retrieval of distant versus recently experienced events

    Big-Bang Nucleosynthesis and Hadronic Decay of Long-Lived Massive Particles

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    We study the big-bang nucleosynthesis (BBN) with the long-lived exotic particle, called X. If the lifetime of X is longer than \sim 0.1 sec, its decay may cause non-thermal nuclear reactions during or after the BBN, altering the predictions of the standard BBN scenario. We pay particular attention to its hadronic decay modes and calculate the primordial abundances of the light elements. Using the result, we derive constraints on the primordial abundance of X. Compared to the previous studies, we have improved the following points in our analysis: The JETSET 7.4 Monte Carlo event generator is used to calculate the spectrum of hadrons produced by the decay of X; The evolution of the hadronic shower is studied taking account of the details of the energy-loss processes of the nuclei in the thermal bath; We have used the most recent observational constraints on the primordial abundances of the light elements; In order to estimate the uncertainties, we have performed the Monte Carlo simulation which includes the experimental errors of the cross sections and transfered energies. We will see that the non-thermal productions of D, He3, He4 and Li6 provide stringent upper bounds on the primordial abundance of late-decaying particle, in particular when the hadronic branching ratio of X is sizable. We apply our results to the gravitino problem, and obtain upper bound on the reheating temperature after inflation.Comment: 94 pages, 49 figures, to appear in Phys. Rev. D. This is a full length paper of the preprint astro-ph/040249

    Risk aversion in the use of complex kidneys in paired exchange programs: Opportunities for even more transplants?

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    This retrospective review of the largest United States kidney exchange reports characteristics, utilization, and recipient outcomes of kidneys with simple compared to complex anatomy and extrapolates reluctance to accept these kidneys. Of 3105 transplants performed, only 12.8% were right kidneys and 23.1% had multiple renal arteries. 59.3% of centers used fewer right kidneys than expected and 12.1% transplanted zero right kidneys or kidneys with more than 1 artery. Five centers transplanted a third of these kidneys (35.8% of right kidneys and 36.7% of kidneys with multiple renal arteries). 22.5% and 25.5% of centers currently will not entertain a match offer for a left or right kidney with more than one artery, respectively. There were no significant differences in all-cause graft failure or death-censored graft loss for kidneys with multiple arteries, and a very small increased risk of graft failure for right kidneys versus left of limited clinical relevance for most recipients. Kidneys with complex anatomy can be used with excellent outcomes at many centers. Variation in use (lack of demand) for these kidneys reduces the number of transplants, so systems to facilitate use could increase demand. We cannot know how many donors are turned away because perceived demand is limited.Wiley Read-and-Publish Agreemen

    Influence of FK 506 (tacrolimus) on circulating CD4 <sup>+</sup> t cells expressing cd25 and cd45ra antigens in 19 patients with chronic progressive multiple sclerosis participating in an open label drug safety trial

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    We have taken the opportunity of a clinical trial of the potential efficacy and safety of FK 506 (tacrolimus) in chronic progressive multiple sclerosis (MS) to examine the influence of this potent new immunosuppressant on circulating T-lymphocytes in an otherwise healthy non-transplant population. Peripheral blood levels of subsets of CD4+ T lymphocytes expressing the activation molecule interleukin-2 receptor (p55 α chain; CD25) or the CD45RA isoform were determined sequentially in 19 patients that were treated continuously with oral FK 506 (starting dose 0.15 mg/kg/day) for 12 months. No significant change in the proportion of circulating CD25 + CD4+ cells was observed over the study period in which the mean trough plasma FK 506 level rose from 0.3 ±0.2 to 0.5 ±0.4 ng/ml. There was also no significant effect of FK 506 on the percentage of CD45RA + CD4 + cells in the peripheral blood at 12 months compared with pretreatment values. Analysis of a subgroup of 7 patients, who showed a sustained reduction in CD25 + CD4+ cells and a reciprocal increase in CD45RA* CD4 * cells for at least 6 months after start of treatment, did not reveal any difference in disability at one year compared with the treatment group as a whole. The side effects of FK 506 were mild and the overall degree of disability estimated by the mean Kurtzke expanded disability status scale (EDSS) score or the ambulation index did not deteriorate significantly in the 19 patients studied over the 12 months of FK 506 administration. © 1994 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

    Two-body Photodisintegration of 4^{4}He with Full Final State Interaction

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    The cross sections of the processes 4^4He(Îł,p\gamma,p)3^3H and 4^4He(Îł,n\gamma,n)3^3He are calculated taking into account the full final state interaction via the Lorentz integral transform (LIT) method. This is the first consistent microscopic calculation beyond the three--body breakup threshold. The results are obtained with a semirealistic central NN potential including also the Coulomb force. The cross sections show a pronounced dipole peak at 27 MeV which lies within the rather broad experimental band. At higher energies, where experimental uncertainties are considerably smaller, one finds a good agreement between theory and experiment. The calculated sum of three-- and four--body photodisintegration cross sections is also listed and is in fair agreement with the data.Comment: 18 pages, 6 figure
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