2,864 research outputs found

    Field Evidence Against Rodent Burrow Entering by \u3ci\u3eAedes Triseriatus\u3c/i\u3e (Diptera: Culicidae)

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    (excerpt) The tree-hole developing mosquito Aedes triseriatus (Say) is the major vector of La Crosse encephalitis virus in the upper mid-western United States (Calisher and Thompson 1983). This virus overwinters in the eggs of this mosquito, and in the summer infects chipmunks and squirrels which have been bitten by infected mosquitoes (op. cit). Non-infected mosquitoes may become infected when they blood-feed on viremic sciurid rodents (Pantuwatana et al. 1972)

    Straw Itch Mite, \u3ci\u3ePyemotes Tritici\u3c/i\u3e, Infestation in Brome Seed Related to Acute Dermatitis in Michigan Granary Workers

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    An infestation of Pyemotes tritici, the straw itch mite, apparently caused dermatitis on the arms and trunks of four workers in south-central Michigan who had unloaded a shipment of brome seed bags. Sampling of bag surfaces and contents indicated that mites occurred inside and on the surface of brome seed bags, but not in bags of other seed present at the site. One bag of fescue in contact with brome seed bags had mites on its surface. Pyemotes tritici densities on the brome seed bags ranged from 0.7 -5.6 per cm , while infestations in brome seed ranged from 0.08-0.33 mites per ml of seed. An insect repellent containing DEET was effective in preventing mite bites

    Seasonal Abundance and Species Diversity of Adult Tabanidae (Diptera) at Lake Lansing Park-North, Michigan

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    A two year study was undertaken to determine the seasonal abundance and diversity of adult deer flies and horse flies, to compare two methods of sampling (Malaise trap and sweep net), and to estimate attack rates by tabanids on people at Lake Lansing Park-North, Ingham County, Michigan, in 1990 and 1991. Tabanids were sampled using dry ice-baited Malaise traps, and by making over- head sweeps with a standard insect net while hiking a trail. Hybomitra spp. (299 individuals of 9 species) peaked in abundance in mid-May to early June in both years. Chrysops spp. (11,675 individuals of 14 species) and Tabanus spp. (324 individuals of 8 species) peaked in early-to late-July in both study years. Peak abundance for Chrysops and Tabanus spp. occurred earlier in 1991 than 1990, probably because the spring of 1991 was warmer. There were six new species records for County. More individual Hybomitra and Tabanus were taken by M traps (77.3% for Hybomitra; 76.2% for Tabanus) than by netting (22.7% for Hybomitra; 23.8% for Tabanus). In contrast, sweep netting yielded more individual Chrysops (98.3%) than Malaise traps (1.7%). Tabanid attack rates on people hiking the trail exceeded 1,000 per hour on one occasion each year, at mid-season

    \u3ci\u3eIxodes Dentatus\u3c/i\u3e (Acari: Ixodidae) in Michigan: First State Records and Occurrence on a Human

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    An Ixodes dentatus adult female was taken from a cottontail rabbit in Kalamazoo County, and a nymph from a child in Berrien County, in 1992 in Michigan. These findings represent the first records of I.dentatus in the state, and document an unusual parasitization of a human being by this species of tick

    Association of West Nile virus illness and urban landscapes in Chicago and Detroit

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    BACKGROUND: West Nile virus infection in humans in urban areas of the Midwestern United States has exhibited strong spatial clustering during epidemic years. We derived urban landscape classes from the physical and socio-economic factors hypothesized to be associated with West Nile Virus (WNV) transmission and compared those to human cases of illness in 2002 in Chicago and Detroit. The objectives were to improve understanding of human exposure to virus-infected mosquitoes in the urban context, and to assess the degree to which environmental factors found to be important in Chicago were also found in Detroit. RESULTS: Five urban classes that partitioned the urban space were developed for each city region. The classes had many similarities in the two settings. In both regions, the WNV case rate was considerably higher in the urban class associated with the Inner Suburbs, where 1940–1960 era housing dominates, vegetation cover is moderate, and population density is moderate. The land cover mapping approach played an important role in the successful and consistent classification of the urban areas. CONCLUSION: The analysis demonstrates how urban form and past land use decisions can influence transmission of a vector-borne virus. In addition, the results are helpful to develop hypotheses regarding urban landscape features and WNV transmission, they provide a structured method to stratify the urban areas to locate representative field study sites specifically for WNV, and this analysis contributes to the question of how the urban environment affects human health

    Magellan/M2FS Spectroscopy of Galaxy Clusters: Stellar Population Model and Application to Abell 267

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    We report the results of a pilot program to use the Magellan/M2FS spectrograph to survey the galactic populations and internal kinematics of galaxy clusters. For this initial study, we present spectroscopic measurements for 223223 quiescent galaxies observed along the line of sight to the galaxy cluster Abell 267 (z0.23z\sim0.23). We develop a Bayesian method for modeling the integrated light from each galaxy as a simple stellar population, with free parameters that specify redshift (vlos/cv_\mathrm{los}/c) and characteristic age, metallicity ([Fe/H]\mathrm{[Fe/H]}), alpha-abundance ([α/Fe][\alpha/\mathrm{Fe}]), and internal velocity dispersion (σint\sigma_\mathrm{int}) for individual galaxies. Parameter estimates derived from our 1.5-hour observation of A267 have median random errors of σvlos=20 km s1\sigma_{v_\mathrm{los}}=20\ \mathrm{km\ s^{-1}}, σAge=1.2 Gyr\sigma_{\mathrm{Age}}=1.2\ \mathrm{Gyr}, $\sigma_{\mathrm{[Fe/H]}}=0.11\ \mathrm{dex},, \sigma_{[\alpha/\mathrm{Fe}]}=0.07\ \mathrm{dex},and, and \sigma_{\sigma_\mathrm{int}}=20\ \mathrm{km\ s^{-1}}$. In a companion paper, we use these results to model the structure and internal kinematics of A267.Comment: 16 pages, 11 figures, accepted for publication in The Astronomical Journa

    Vaccine-preventable haemophilus influenza type B disease burden and cost-effectiveness of infant vaccination in Indonesia.

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    BACKGROUND: Most of Asia, including Indonesia, does not use Haemophilus influenzae type b (Hib) conjugate vaccines. We estimated total vaccine-preventable disease burden and the cost-effectiveness of Hib conjugate vaccine in Indonesia. METHODS: Hib pneumonia and meningitis incidences for children with access to health care were derived from a randomized vaccine probe study on Lombok Island, Indonesia during 1998-2002. Incidences were adjusted for limited access to care. Health system and patient out-of-pocket treatment cost data were collected concurrent with the probe study. For Hib vaccine in monovalent and combined (with DTP-HepB) presentations, we used 2007 UNICEF vaccine prices of US3.30and3.30 and 3.75 per dose. RESULTS: For the 2007 Indonesian birth cohort, Hib vaccine would prevent meningitis in 1 of every 179 children, pneumonia in 1 of every 18 children, and 4.9% of mortality among those younger than 5 years. The total incremental societal costs of introducing Hib vaccine in monovalent and pentavalent presentations were, respectively, US11.74and11.74 and 8.93 per child vaccinated. Annual discounted treatment costs averted amounted to 20% of pentavalent vaccine costs. For the pentavalent vaccine, the incremental costs per discounted death and disability adjusted life-year averted amounted to US3102and3102 and 74, respectively, versus 4438and4438 and 102 for monovalent vaccine. CONCLUSIONS: Routine infant Hib vaccination would prevent a large burden of pediatric illness and death in Indonesia. Even without external funding support, Hib vaccine will be a highly cost-effective intervention in either a monovalent or pentavalent presentation based on commonly used benchmarks

    Detailed Chemical Abundances in the r-Process-Rich Ultra-Faint Dwarf Galaxy Reticulum 2

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    The ultra-faint dwarf galaxy Reticulum 2 (Ret 2) was recently discovered in images obtained by the Dark Energy Survey. We have observed the four brightest red giants in Ret 2 at high spectral resolution using the Michigan/Magellan Fiber System. We present detailed abundances for as many as 20 elements per star, including 12 elements heavier than the Fe group. We confirm previous detection of high levels of r-process material in Ret 2 (mean [Eu/Fe]=+1.69+/-0.05) found in three of these stars (mean [Fe/H]=-2.88+/-0.10). The abundances closely match the r-process pattern found in the well-studied metal-poor halo star CS22892-052. Such r-process-enhanced stars have not been found in any other ultra-faint dwarf galaxy, though their existence has been predicted by at least one model. The fourth star in Ret 2 ([Fe/H]=-3.42+/-0.20) contains only trace amounts of Sr ([Sr/Fe]=-1.73+/-0.43) and no detectable heavier elements. One r-process enhanced star is also enhanced in C (natal [C/Fe]=+1.1). This is only the third such star known, which suggests that the nucleosynthesis sites leading to C and r-process enhancements are decoupled. The r-process-deficient star is enhanced in Mg ([Mg/Fe]=+0.81+/-0.14), and the other three stars show normal levels of alpha-enhancement (mean [Mg/Fe]=+0.34+/-0.03). The abundances of other alpha and Fe-group elements closely resemble those in ultra-faint dwarf galaxies and metal-poor halo stars, suggesting that the nucleosynthesis that led to the large r-process enhancements either produced no light elements or produced light-element abundance signatures indistinguishable from normal supernovae.Comment: Accepted for publication in the Astronomical Journal. 12 pages, 6 figures, 8 table

    The Mass of the Black Hole in the Seyfert 1 Galaxy NGC 4593 from Reverberation Mapping

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    We present new observations leading to an improved black hole mass estimate for the Seyfert 1 galaxy NGC 4593 as part of a reverberation-mapping campaign conducted at the MDM Observatory. Cross-correlation analysis of the H_beta emission-line light curve with the optical continuum light curve reveals an emission-line time delay of 3.73 (+-0.75) days. By combining this time delay with the H_beta line width, we derive a central black hole mass of M_BH = 9.8(+-2.1)x10^6 M_sun, an improvement in precision of a factor of several over past results.Comment: 22 pages, 3 tables, 5 figures, accepted for publication in Ap
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