2,231 research outputs found
Portable dynamic fundus instrument
A portable diagnostic image analysis instrument is disclosed for retinal funduscopy in which an eye fundus image is optically processed by a lens system to a charge coupled device (CCD) which produces recordable and viewable output data and is simultaneously viewable on an electronic view finder. The fundus image is processed to develop a representation of the vessel or vessels from the output data
Inpatient Management of Bronchial Asthma for the Hospitalist
Asthma is a common inflammatory disease of the airways that leads to significant hospital utilization and health care cost around the world. Despite published guidelines, the diagnosis and treatment of acute asthma exacerbation varies widely due to inconsistent compliance with guidelines. We will review the evidence, guideline recommendations, clinical presentation, risk factors, and management of acute asthma exacerbations, including standard and advanced treatment options for refractory cases.Michael P. Hunter (1), Suman Vaddi (1), Armin Krvavac (1), Hariharan Regunath (1,2), Vamsi P. Guntur (3); 1. Department of Medicine, Division of Pulmonary, Critical Care, and Environmental Medicine, University of Missouri. 2. Department of Medicine, Division of Infectious Diseases, University of Missouri. 3. Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, National Jewish Health.Includes bibliographical reference
Thermal Instability-Induced Interstellar Turbulence
We study the dynamics of phase transitions in the interstellar medium by
means of three-dimensional hydrodynamic numerical simulations. We use a
realistic cooling function and generic nonequilibrium initial conditions to
follow the formation history of a multiphase medium in detail in the absence of
gravity. We outline a number of qualitatively distinct stages of this process,
including a linear isobaric evolution, transition to an isochoric regime,
formation of filaments and voids (also known as "thermal" pancakes), the
development and decay of supersonic turbulence, an approach to pressure
equilibrium, and final relaxation of the multiphase medium. We find that 1%-2%
of the initial thermal energy is converted into gas motions in one cooling
time. The velocity field then randomizes into turbulence that decays on a
dynamical timescale E_k ~ t^-n, 1 < n < 2. While not all initial conditions
yield a stable two-phase medium, we examine such a case in detail. We find that
the two phases are well mixed with the cold clouds possessing a fine-grained
structure near our numerical resolution limit. The amount of gas in the
intermediate unstable phase roughly tracks the rms turbulent Mach number,
peaking at 25% when M_rms ~ 8, decreasing to 11% when M_rms ~ 0.4.Comment: To appear in the ApJ Letters, April 2002; 5 pages, 3 color figures,
mpeg animations available at http://akpc.ucsd.edu/ThermalLetter/thermal.htm
Development of a telescope for medium-energy gamma-ray astronomy
The Advanced Energetic Pair Telescope (AdEPT) is being developed at GSFC as a future NASA MIDEX mission to explore the medium-energy (5–200 MeV) gamma-ray range. The enabling technology for AdEPT is the Three- Dimensional Track Imager (3-DTI), a gaseous time projection chamber. The high spatial resolution 3-D electron tracking of 3-DTI enables AdEPT to achieve high angular resolution gamma-ray imaging via pair production and triplet production (pair production on electrons) in the medium-energy range. The low density and high spatial resolution of 3-DTI allows the electron positron track directions to be measured before they are dominated by Coulomb scattering. Further, the significant reduction of Coulomb scattering allows AdEPT to be the first medium-energy gamma-ray telescope to have high gamma-ray polarization sensitivity. We review the science goals that can be addressed with a medium-energy pair telescope, how these goals drive the telescope design, and the realization of this design with AdEPT. The AdEPT telescope for a future MIDEX mission is envisioned as a 8 m3 active volume filled with argon at 2 atm. The design and performance of the 3-DTI detectors for the AdEPT telescope are described as well as the outstanding instrument challenges that need to be met for the AdEPT mission
Wildlife Management Practices Associated with Pathogen Exposure in Non-NativeWild Pigs in Florida, U.S.
Land use influences disease emergence by changing the ecological dynamics of humans, wildlife, domestic animals, and pathogens. This is a central tenet of One Health, and one that is gaining momentum in wildlife management decision-making in the United States. Using almost 2000 serological samples collected from non-native wild pigs (Sus scrofa) throughout Florida (U.S.), we compared the prevalence and exposure risk of two directly transmitted pathogens, pseudorabies virus (PrV) and Brucella spp., to test the hypothesis that disease emergence would be positively correlated with one of the most basic wildlife management operations: Hunting. The seroprevalence of PrV-Brucella spp. coinfection or PrV alone was higher for wild pigs in land management areas that allowed hunting with dogs than in areas that culled animals using other harvest methods. This pattern did not hold for Brucella alone. The likelihood of exposure to PrV, but not Brucella spp., was also significantly higher among wild pigs at hunted sites than at sites where animals were culled. By failing to consider the impact of dog hunting on the emergence of non-native pathogens, current animal management practices have the potential to affect public health, the commercial livestock industry, and wildlife conservation
Wildlife Management Practices Associated with Pathogen Exposure in Non-NativeWild Pigs in Florida, U.S.
Land use influences disease emergence by changing the ecological dynamics of humans, wildlife, domestic animals, and pathogens. This is a central tenet of One Health, and one that is gaining momentum in wildlife management decision-making in the United States. Using almost 2000 serological samples collected from non-native wild pigs (Sus scrofa) throughout Florida (U.S.), we compared the prevalence and exposure risk of two directly transmitted pathogens, pseudorabies virus (PrV) and Brucella spp., to test the hypothesis that disease emergence would be positively correlated with one of the most basic wildlife management operations: Hunting. The seroprevalence of PrV-Brucella spp. coinfection or PrV alone was higher for wild pigs in land management areas that allowed hunting with dogs than in areas that culled animals using other harvest methods. This pattern did not hold for Brucella alone. The likelihood of exposure to PrV, but not Brucella spp., was also significantly higher among wild pigs at hunted sites than at sites where animals were culled. By failing to consider the impact of dog hunting on the emergence of non-native pathogens, current animal management practices have the potential to affect public health, the commercial livestock industry, and wildlife conservation
Fermi-LAT Sensitivity to Dark Matter Annihilation in Via Lactea II Substructure
We present a study of the ability of the Fermi Gamma-ray Space Telescope to
detect dark-matter annihilation signals from the Galactic subhalos predicted by
the Via Lactea II N-body simulation. We implement an improved formalism for
estimating the boost factor needed to account for the effect of dark-matter
clumping on scales below the resolution of the simulation, and we incorporate a
detailed Monte Carlo simulation of the response of the Fermi-LAT telescope,
including a simulation of its all-sky observing mode integrated over a ten year
mission. We find that for WIMP masses up to about 150 GeV in standard
supersymmetric models with velocity-averaged cross section 3*10^-26 cm^3 s^-1,
a few subhalos could be detectable with >5 standard deviations significance and
would likely deviate significantly from the appearance of a point source.Comment: 16 pages, 6 figure
The non-thermal superbubble in IC 10 : the generation of cosmic ray electrons caught in the act
Superbubbles are crucial for stellar feedback, with supposedly high (of the order of 10 per cent) thermalization rates. We combined multiband radio continuum observations from the Very Large Array (VLA) with Effelsberg data to study the non-thermal superbubble (NSB) in IC 10, a starburst dwarf irregular galaxy in the Local Group. Thermal emission was subtracted using a combination of Balmer Hα and VLA 32 GHz continuum maps. The bubble’s nonthermal spectrum between 1.5 and 8.8 GHz displays curvature and can be well fitted with a standard model of an ageing cosmic ray electron population. With a derived equipartition magnetic field strength of 44 ±8 μG, and measuring the radiation energy density from Spitzer MIPS maps as 5±1×10−11 erg cm−3, we determine, based on the spectral curvature, a spectral age of the bubble of 1.0 ± 0.3 Myr. Analysis of the LITTLE THINGS HI data cube shows an expanding HI hole with 100 pc diameter and a dynamical age of 3.8 ± 0.3 Myr, centred to within 16 pc on IC 10 X-1, a massive stellar mass black hole (M > 23 M⊙). The results are consistent with the expected evolution for a superbubble with a few massive stars, where a very energetic event like a Type Ic supernova/hypernova has taken place about 1 Myr ago. We discuss alternatives to this interpretationPeer reviewe
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