374 research outputs found
Developing a Comprehensive Pesticide Health Effects Tracking System for an Urban Setting: New York City’s Approach
In recent years, there have been substantial investments and improvements in federal and state surveillance systems to track the health effects from pesticide exposure. These surveillance systems help to identify risk factors for occupational exposure to pesticides, patterns in poisonings, clusters of disease, and populations at risk of exposure from pesticide use. Data from pesticide use registries and recent epidemiologic evidence pointing to health risks from urban residential pesticide use make a strong case for understanding better the sale, application, and use of pesticides in cities. In this article, we describe plans for the development of a pesticide tracking system for New York City that will help to elucidate where and why pesticides are used, potential risks to varied populations, and the health consequences of their use. The results of an inventory of data sources are presented along with a description of their relevance to pesticide tracking. We also discuss practical, logistical, and methodologic difficulties of linking multiple secondary data sources with different levels of person, place, and time descriptors
Adiabatic creation of coherent superposition states via multiple intermediate states
We consider an adiabatic population transfer process that resembles the well
established stimulated Raman adiabatic passage (STIRAP). In our system, the
states have nonzero angular momentums , therefore, the coupling laser fields
induce transitions among the magnetic sublevels of the states. In particular,
we discuss the possibility of creating coherent superposition states in a
system with coupling pattern and . Initially, the system is in the J=0 state. We show that by two delayed,
overlapping laser pulses it is possible to create any final superposition state
of the magnetic sublevels , , . Moreover, we find that
the relative phases of the applied pulses influence not only the phases of the
final superposition state but the probability amplitudes as well. We show that
if we fix the shape and the time-delay between the pulses, the final state
space can be entirely covered by varying the polarizations and relative phases
of the two pulses. Performing numerical simulations we find that our transfer
process is nearly adiabatic for the whole parameter set.Comment: 7 pages, 10 figure
Quantum trajectory approach to stochastically-induced quantum interference effects in coherently-driven two-level atoms
Stochastic perturbation of two-level atoms strongly driven by a coherent
light field is analyzed by the quantum trajectory method. A new method is
developed for calculating the resonance fluorescence spectra from numerical
simulations. It is shown that in the case of dominant incoherent perturbation,
the stochastic noise can unexpectedly create phase correlation between the
neighboring atomic dressed states. This phase correlation is responsible for
quantum interference between the related transitions resulting in anomalous
modifications of the resonance fluorescence spectra.Comment: paper accepted for publicatio
The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
The Infrared Array Camera (IRAC) is one of three focal plane instruments in
the Spitzer Space Telescope. IRAC is a four-channel camera that obtains
simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 microns. Two nearly
adjacent 5.2x5.2 arcmin fields of view in the focal plane are viewed by the
four channels in pairs (3.6 and 5.8 microns; 4.5 and 8 microns). All four
detector arrays in the camera are 256x256 pixels in size, with the two shorter
wavelength channels using InSb and the two longer wavelength channels using
Si:As IBC detectors. IRAC is a powerful survey instrument because of its high
sensitivity, large field of view, and four-color imaging. This paper summarizes
the in-flight scientific, technical, and operational performance of IRAC.Comment: 7 pages, 3 figures. Accepted for publication in the ApJS. A higher
resolution version is at http://cfa-www.harvard.edu/irac/publication
Competitive stochastic noises in coherently driven two-level atoms and quantum interference
A system of coherently-driven two-level atoms is analyzed in presence of two
independent stochastic perturbations: one due to collisions and a second one
due to phase fluctuations of the driving field. The behaviour of the quantum
interference induced by the collisional noise is considered in detail. The
quantum-trajectory method is utilized to reveal the phase correlations between
the dressed states involved in the interfering transition channels. It is shown
that the quantum interference induced by the collisional noise is remarkably
robust against phase noise. This effect is due to the fact that the phase
noise, similarly to collisions, stabilizes the phase-difference between the
dressed states.Comment: accepted for publication in J. Opt.
Dystrophin expression in muscle following gene transfer with a fully deleted ("Gutted") adenovirus is markedly improved by Trans-acting adenoviral gene products
Helper-dependent adenoviruses (HDAd) are Ad vectors lacking all or most viral genes. They hold great promise for gene therapy of diseases such as Duchenne muscular dystrophy (DMD), because they are less immunogenic than E1/E3-deleted Ad (first-generation Ad or FGAd) and can carry the full-length (Fl) dystrophin (dys) cDNA (12 kb). We have compared the transgene expression of a HDAd (HDAdCMVDysFl) and a FGAd (FGAdCMV-dys) in cell culture (HeLa, C2C12 myotubes) and in the muscle of mdx mice (the mouse model for DMD). Both vectors encoded dystrophin regulated by the same cytomegalovirus (CMV) promoter. We demonstrate that the amount of dystrophin expressed was significantly higher after gene transfer with FGAdCMV-dys compared to HDAdCMVDysFl both in vitro and in vivo. However, gene transfer with HDAdCMVDysFl in the presence of a FGAd resulted in a significant increase of dystrophin expression indicating that gene products synthesized by the FGAd increase, in trans, the amount of dystrophin produced. This enhancement occurred in cell culture and after gene transfer in the muscle of mdx mice and dystrophic golden retriever (GRMD) dogs, another animal model for DMD. The E4 region of Ad is required for the enhancement, because no increase of dystrophin expression from HDAdCMVDysFl was observed in the presence of an E1/E4-deleted Ad in vitro and in vivo. The characterization of these enhancing gene products followed by their inclusion into an HDAd may be required to produce sufficient dystrophin to mitigate the pathology of DMD by HDAd-mediated gene transfer
An Outbreak of Rift Valley Fever in Northeastern Kenya, 1997-98
In December 1997, 170 hemorrhagic fever-associated deaths were reported in Carissa District, Kenya. Laboratory testing identified evidence of acute Rift Valley fever virus (RVFV). Of the 171 persons enrolled in a cross-sectional study, 31(18%) were anti-RVFV immunoglobulin (Ig) M positive. An age-adjusted IgM antibody prevalence of 14% was estimated for the district. We estimate approximately 27,500 infections occurred in Garissa District, making this the largest recorded outbreak of RVFV in East Africa. In multivariate analysis, contact with sheep body fluids and sheltering livestock in one’s home were significantly associated with infection. Direct contact with animals, particularly contact with sheep body fluids, was the most important modifiable risk factor for RVFV infection. Public education during epizootics may reduce human illness and deaths associated with future outbreaks
Have I grooved to this before? Discriminating practised and observed actions in a novel context
Learning a new motor skill typically requires converting actions observed from a third-person perspective into fluid motor commands executed from a first-person perspective. In the present study, we test the hypothesis that during motor learning, the ability to discriminate between actions that have been observed and actions that have been executed is associated with learning aptitude, as assessed by a general measure of physical performance. Using a multi-day dance-training paradigm with a group of dance-naïve participants, we investigated whether actions that had been regularly observed could be discriminated from similar actions that had been physically practised over the course of three days, or a further set of similar actions that remained untrained. Training gains and performance scores at test were correlated with participants' ability to discriminate between observed and practised actions, suggesting that an individual's ability to differentiate between visual versus visuomotor action encoding is associated with general motor learning
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