1,120 research outputs found
Modeling reservoir management for malaria control in Ethiopia
This study investigated how changes in reservoir water level affect mosquito abundance and malaria transmission in Ethiopia. Digital elevation models of three Ethiopian dams at lowland, midland and highland elevations were used to quantify water surface area and wetted shoreline at different reservoir water levels (70, 75, 80, 85, 90, 95 and 100% full capacity) to estimate surface area of potential mosquito breeding habitat. Reservoir water level drawdown rates of 10, 15 and 20 mm.day-1 were applied as scenarios to model larval abundance, entomological inoculation rate (EIR) and malaria prevalence at each dam. Malaria treatment cost and economic cost in terms of lost working days were calculated for each water level scenario and dam. At the lowland dam, increased larval abundances were associated with increasing reservoir water level and wetted shoreline area. In contrast, both larval abundances and area of wetted shoreline declined with increasing reservoir water level at the midland and highland dams. Estimated EIR, malaria prevalence, malaria treatment cost and economic cost generally decreased when the water level drawdown rate increased from 10 to 15 and 20 mm.day-1 irrespective of reservoir water level. Given the expansion of dam construction in sub-Saharan Africa, incorporating malaria control measures such as manipulating drawdown rates into reservoir management has the potential to reduce the malaria burden and health care costs in communities near reservoirs
Muon Simulations for Super-Kamiokande, KamLAND and CHOOZ
Muon backgrounds at Super-Kamiokande, KamLAND and CHOOZ are calculated using
MUSIC. A modified version of the Gaisser sea level muon distribution and a
well-tested Monte Carlo integration method are introduced. Average muon energy,
flux and rate are tabulated. Plots of average energy and angular distributions
are given. Implications on muon tracker design for future experiments are
discussed.Comment: Revtex4 33 pages, 16 figures and 4 table
The cryomechanical design of MUSIC: a novel imaging instrument for millimeter-wave astrophysics at the Caltech Submillimeter Observatory
MUSIC (Multicolor Submillimeter kinetic Inductance Camera) is a new facility instrument for the Caltech Submillimeter Observatory (Mauna Kea, Hawaii) developed as a collaborative effect of Caltech, JPL, the University of Colorado at Boulder and UC Santa Barbara, and is due for initial commissioning in early 2011. MUSIC utilizes a new class of superconducting photon detectors known as microwave kinetic inductance detectors (MKIDs), an emergent technology that offers considerable advantages over current types of detectors for submillimeter and millimeter direct detection. MUSIC will operate a focal plane of 576 spatial pixels, where each pixel is a slot line antenna coupled to multiple detectors through on-chip, lumped-element filters, allowing simultaneously imaging in four bands at 0.86, 1.02, 1.33 and 2.00 mm. The MUSIC instrument is designed for closed-cycle operation, combining a pulse tube cooler with a two-stage Helium-3 adsorption refrigerator, providing a focal plane temperature of 0.25 K with intermediate temperature stages at approximately 50, 4 and 0.4 K for buffering heat loads and heat sinking of optical filters. Detector readout is achieved using semi-rigid coaxial cables from room temperature to the focal plane, with cryogenic HEMT amplifiers operating at 4 K. Several hundred detectors may be multiplexed in frequency space through one signal line and amplifier. This paper discusses the design of the instrument cryogenic hardware, including a number of features unique to the implementation of superconducting detectors. Predicted performance data for the instrument system will also be presented and discussed
Near-Infrared Synchrotron Emission from Cas A
High energy observations of Cas A suggested the presence of synchrotron
radiation, implying acceleration of cosmic rays by young supernova remnants. We
detect synchrotron emission from Cas A in the near-infrared using Two Micron
All Sky Survey (2MASS) and Palomar 200 inch PFIRCAM observations. The remnant
is detected in J, H, and Ks bands, with Ks band brightest and J faint. In the J
and H bands, bright [Fe II] lines (1.24um and 1.64um) are detected
spectroscopically. The Palomar observations include Ks continuum, narrow-band
1.64um (centered on [Fe II]) and 2.12um (centered on H2(1-0)) images. While the
narrow-band 1.64um image shows filamentary and knotty structures, similar to
the optical image, the Ks image shows a relatively smooth, diffuse shell,
remarkably similar to the radio image. The broad-band near-infrared fluxes of
Cas A are generally consistent with, but a few tens of percent higher than, an
extrapolation of the radio fluxes. The hardening to higher frequencies is
possibly due to nonlinear shock acceleration and/or spectral index variation
across the remnant. We show evidence of spectral index variation. The presence
of near-infrared synchrotron radiation requires the roll-off frequency to be
higher than 1.5e14 Hz, implying that electrons are accelerated to energies of
at least 0.2 TeV. The morphological similarity in diffuse emission between the
radio and Ks band images implies that synchrotron losses are not dominant. Our
observations show unambiguous evidence that the near-infrared Ks band emission
of Cas A is from synchrotron emission by accelerated cosmic-ray electrons.Comment: accepted by Ap
The AzTEC mm-Wavelength Camera
AzTEC is a mm-wavelength bolometric camera utilizing 144 silicon nitride
micromesh detectors. Herein we describe the AzTEC instrument architecture and
its use as an astronomical instrument. We report on several performance metrics
measured during a three month observing campaign at the James Clerk Maxwell
Telescope, and conclude with our plans for AzTEC as a facility instrument on
the Large Millimeter Telescope.Comment: 13 pages, 15 figures, accepted for publication in Monthly Notice
AzTEC millimeter survey of the COSMOS field - III. Source catalog over 0.72 sq. deg. and plausible boosting by large-scale structure
We present a 0.72 sq. deg. contiguous 1.1mm survey in the central area of the
COSMOS field carried out to a 1sigma ~ 1.26 mJy/beam depth with the AzTEC
camera mounted on the 10m Atacama Submillimeter Telescope Experiment (ASTE). We
have uncovered 189 candidate sources at a signal-to-noise ratio S/N >= 3.5, out
of which 129, with S/N >= 4, can be considered to have little chance of being
spurious (< 2 per cent). We present the number counts derived with this survey,
which show a significant excess of sources when compared to the number counts
derived from the ~0.5 sq. deg. area sampled at similar depths in the Scuba HAlf
Degree Extragalactic Survey (SHADES, Austermann et al. 2010). They are,
however, consistent with those derived from fields that were considered too
small to characterize the overall blank-field population. We identify
differences to be more significant in the S > 5 mJy regime, and demonstrate
that these excesses in number counts are related to the areas where galaxies at
redshifts z < 1.1 are more densely clustered. The positions of optical-IR
galaxies in the redshift interval 0.6 < z < 0.75 are the ones that show the
strongest correlation with the positions of the 1.1mm bright population (S > 5
mJy), a result which does not depend exclusively on the presence of rich
clusters within the survey sampled area. The most likely explanation for the
observed excess in number counts at 1.1mm is galaxy-galaxy and galaxy-group
lensing at moderate amplification levels, that increases in amplitude as one
samples larger and larger flux densities. This effect should also be detectable
in other high redshift populations.Comment: 21 pages, 17 figures, accepted for publication in MNRA
Investigating the psychometric properties of the Suicide Stroop task
Behavioral measures are increasingly used to assess suicidal thoughts and behaviors. Some measures, such as the Suicide Stroop Task, have yielded mixed findings in the literature. An understudied feature of these behavioral measures has been their psychometric properties, which may affect the probability of detecting significant effects and reproducibility. In the largest investigation of its kind, we tested the internal consistency and concurrent validity of the Suicide Stroop Task in its current form, drawing from seven separate studies (N = 875 participants, 64% female, aged 12 to 81 years). Results indicated that the most common Suicide Stroop scoring approach, interference scores, yielded unacceptably low internal consistency (rs = -.09-.13) and failed to demonstrate concurrent validity. Internal consistency coefficients for mean reaction times (RTs) to each stimulus type ranged from rs = .93-.94. All scoring approaches for suicide-related interference demonstrated poor classification accuracy (AUCs = .52-.56) indicating that scores performed near chance in their ability to classify suicide attempters from nonattempters. In the case of mean RTs, we did not find evidence for concurrent validity despite our excellent reliability findings, highlighting that reliability does not guarantee a measure is clinically useful. These results are discussed in the context of the wider implications for testing and reporting psychometric properties of behavioral measures in mental health research
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