1,371 research outputs found

    THE ROLE OF PREDATORS IN THE ECOLOGY, EPIDEMIOLOGY, AND SURVEILLANCE OF PLAGUE IN THE UNITED STATES

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    Predators play important roles in the ecology, epidemiology, and surveillance of plague in the United States. Most predators are accidental hosts of plague and, with the possible exception of grasshopper mice (Onychomys spp.), are not important sources of infection for feeding fleas. However, predators undoubtedly do play an important role in the natural cycle of plague by transporting infected fleas between different populations of plague-susceptible rodents. Predators are known to be at least accidental hosts for 40 of the 50 flea species that have been found to be naturally infected with plague in the U.S. Carnivores, including domestic cats, also play an important epidemiological role and have been sources of infection for 24 human plague cases since 1970. Serosurveillance of rodent-consuming carnivores is currently the most cost-effective method of monitoring plague in the western U.S. During the 1990s, these surveys have allowed CDC and other public health agencies to both identify plague risks for humans living in endemic regions and document the spread of plague into areas where it had not been identified previously

    Orbit transfer rocket engine integrated control and health monitoring system technology readiness assessment

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    The objectives of this task were to: (1) estimate the technology readiness of an integrated control and health monitoring (ICHM) system for the Aerojet 7500 lbF Orbit Transfer Vehicle engine preliminary design assuming space based operations; and (2) estimate the remaining cost to advance this technology to a NASA defined 'readiness level 6' by 1996 wherein the technology has been demonstrated with a system validation model in a simulated environment. The work was accomplished through the conduct of four subtasks. In subtask 1 the minimally required functions for the control and monitoring system was specified. The elements required to perform these functions were specified in Subtask 2. In Subtask 3, the technology readiness level of each element was assessed. Finally, in Subtask 4, the development cost and schedule requirements were estimated for bringing each element to 'readiness level 6'

    Nanosecond electron imaging of transient electric fields and material response

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    Electrical pulse stimulation drives many important physical phenomena in condensed matter as well as in electronic systems and devices. Often, nanoscopic and mesoscopic mechanisms are hypothesized, but methods to image electrically driven dynamics on both their native length and time scales have so far been largely undeveloped. Here, we present an ultrafast electron microscopy approach that uses electrical pulses to induce dynamics and records both the local time-resolved electric field and corresponding material behavior with nanometer-nanosecond spatiotemporal resolution. Quantitative measurement of the time-dependent field via the electron beam deflection is demonstrated by recording the field between two electrodes with single-ns temporal resolution. We then show that this can be applied in a material by correlating applied field with resulting dynamics in TaS2_{2}. First, time-resolved electron diffraction is used to simultaneously record the electric field and crystal structure change in a selected region during a 20 ns voltage pulse, showing how a charge density wave transition evolves during and after the applied field. Then, time-resolved nanoimaging is demonstrated, revealing heterogeneous distortions that occur in the freestanding flake during a longer, lower amplitude pulse. Altogether, these results pave the way for future experiments that will uncover the nanoscale dynamics underlying electrically driven phenomena.Comment: Main article: 7 pages, 3 figures. Supplemental Material: 8 pages, 7 figure

    High-gyrotropy seedlayer-free Ce:TbIG for monolithic laser-matched SOI optical isolators

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    Monolithic optical isolators that provide modal (transverse electric, TE) and dimensional (500 nm core) matching to on-chip lasers have been realized with “one step” seedlayer-free garnets. To date, seedlayer-free garnet claddings have required thinner (< 340 nm) silicon-on-insulator (SOI) cores because mode-cladding interactions were too weak for laser-matched cores. However, laser matching is important because tapers, and/or mode converters between the laser and the isolator can cause detrimental reflections prior to isolation. This paper reports the use of cerium-doped terbium iron garnet (Ce:TbIG) in a quasi-phase matched non-reciprocal mode conversion (NRMC) isolator that operates on both TE and TM modes. A key innovation presented here is a repeatable process for foundry-friendly sputter deposition of Ce:TbIG, which enables this high Faraday rotation material (-3200°/cm) to be synthesized in any isolator design that would benefit from one-step lithographical manufacturing. A proof-of-feasibility 500 nm-SOI NRMC device is demonstrated with seedlayer-free Ce:TbIG that achieves an isolation ratio of 11 dB. With an optimal length, this NRMC design can provide greater than 30 dB isolation

    Warfarin Genotyping Reduces Hospitalization Rates Results From the MM-WES (Medco-Mayo Warfarin Effectiveness Study)

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    ObjectivesThis study was designed to determine whether genotype testing for patients initiating warfarin treatment will reduce the incidence of hospitalizations, including those due to bleeding or thromboembolism.BackgroundGenotypic variations in CYP2C9and VKORC1have been shown to predict warfarin dosing, but no large-scale studies have prospectively evaluated the clinical effectiveness of genotyping in naturalistic settings across the U.S.MethodsThis national, prospective, comparative effectiveness study compared the 6-month incidence of hospitalization in patients receiving warfarin genotyping (n = 896) versus a matched historical control group (n = 2,688). To evaluate for temporal changes in the outcomes of warfarin treatment, a secondary analysis compared outcomes for 2 external control groups drawn from the same 2 time periods.ResultsCompared with the historical control group, the genotyped cohort had 31% fewer hospitalizations overall (adjusted hazard ratio [HR]: 0.69, 95% confidence interval [CI]: 0.58 to 0.82, p < 0.001) and 28% fewer hospitalizations for bleeding or thromboembolism (HR: 0.72, 95% CI: 0.53 to 0.97, p = 0.029) during the 6-month follow-up period. Findings from a per-protocol analysis were even stronger: 33% lower risk of all-cause hospitalization (HR: 0.67, 95% CI: 0.55 to 0.81, p < 0.001) and 43% lower risk of hospitalization for bleeding or thromboembolism (HR: 0.57, 95% CI: 0.39 to 0.83, p = 0.003) in patients who were genotyped. During the same period, there was no difference in outcomes between the 2 external control groups.ConclusionsWarfarin genotyping reduced the risk of hospitalization in outpatients initiating warfarin. (The Clinical and Economic Impact of Pharmacogenomic Testing of Warfarin Therapy in Typical Community Practice Settings [MHSMayoWarf1]; NCT00830570

    Experimental heatwaves compromise sperm function and cause transgenerational damage in a model insect

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    Climate change is affecting biodiversity, but proximate drivers remain poorly understood. Here, we examine how experimental heatwaves impact on reproduction in an insect system. Male sensitivity to heat is recognised in endotherms, but ectotherms have received limited attention, despite comprising most of biodiversity and being more influenced by temperature variation. Using a flour beetle model system, we find that heatwave conditions (5 to 7 °C above optimum for 5 days) damaged male, but not female, reproduction. Heatwaves reduce male fertility and sperm competitiveness, and successive heatwaves almost sterilise males. Heatwaves reduce sperm production, viability, and migration through the female. Inseminated sperm in female storage are also damaged by heatwaves. Finally, we discover transgenerational impacts, with reduced reproductive potential and lifespan of offspring when fathered by males, or sperm, that had experienced heatwaves. This male reproductive damage under heatwave conditions provides one potential driver behind biodiversity declines and contractions through global warming

    Seedbank Persistence of Palmer Amaranth (\u3ci\u3eAmaranthus palmeri\u3c/i\u3e) and Waterhemp (\u3ci\u3eAmaranthus tuberculatus\u3c/i\u3e) across Diverse Geographical Regions in the United States

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    Knowledge of the effects of burial depth and burial duration on seed viability and, consequently, seedbank persistence of Palmer amaranth (Amaranthus palmeri S. Watson) and waterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer] ecotypes can be used for the development of efficient weed management programs. This is of particular interest, given the great fecundity of both species and, consequently, their high seedbank replenishment potential. Seeds of both species collected from five different locations across the United States were investigated in seven states (sites) with different soil and climatic conditions. Seeds were placed at two depths (0 and 15cm) for 3 yr. Each year, seeds were retrieved, and seed damage (shrunken, malformed, or broken) plus losses (deteriorated and futile germination) and viability were evaluated. Greater seed damage plus loss averaged across seed origin, burial depth, and year was recorded for lots tested at Illinois (51.3% and 51.8%) followed by Tennessee (40.5% and 45.1%) and Missouri (39.2% and 42%) for A. palmeri and A. tuberculatus, respectively. The site differences for seed persistence were probably due to higher volumetric water content at these sites. Rates of seed demise were directly proportional to burial depth (α=0.001), whereas the percentage of viable seeds recovered after 36 mo on the soil surface ranged from 4.1% to 4.3% compared with 5% to 5.3% at the 15-cm depth for A. palmeri and A. tuberculatus, respectively. Seed viability loss was greater in the seeds placed on the soil surface compared with the buried seeds. The greatest influences on seed viability were burial conditions and time and site-specific soil conditions, more so than geographical location. Thus, management of these weed species should focus on reducing seed shattering, enhancing seed removal from the soil surface, or adjusting tillage systems

    A Case-Control Study of Hantavirus Pulmonary Syndrome during an Outbreak in the Southwestern United States

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    In May 1993, an outbreak of hantavirus pulmonary syndrome( HPS) occurred in the south-western United States. A case-control study determined risk factors for HPS. Seventeen case-patients were compared with 3 groups of controls: members of case-patient households( household controls), members of neighboring households( near controls), and members of randomly selected households ≥ 24 km away ( far controls). Investigators trapped more small rodents at case households than at near ( P = .03) or far control households( P = .02). After the number of small rodents was controlled for,case-patients were more likely than household controls to hand plow (odds ratio [OR], 12.3; 95% confidence interval [ CI], 1.1-143.0) or to clean feed storage areas (OR, 33.4; 95% CI, 1.7-666.0). Case-patients were more likely than near controls to plant( OR, 6.2; 95% CI, 1.1-34.0) and more likely than far controls to clean animal sheds( OR, 11.9;95% CI, 1.4-103.0). Peridomestic cleaning, agricultural activities, and an increased number of small rodents at the household were associated with HPS

    Tick-borne Relapsing Fever Caused by Borrelia hermsii, Montana

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    Five persons contracted tick-borne relapsing fever after staying in a cabin in western Montana. Borrelia hermsii was isolated from the blood of two patients, and Ornithodoros hermsi ticks were collected from the cabin, the first demonstration of this bacterium and tick in Montana. Relapsing fever should be considered when patients who reside or have vacationed in western Montana exhibit a recurring febrile illness
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