1,958 research outputs found
Capillary-gravity waves: The effect of viscosity on the wave resistance
The effect of viscosity on the wave resistance experienced by a 2d
perturbation moving at uniform velocity over the free surface of a fluid is
investigated. The analysis is based on Rayleigh's linearized theory of
capillary-gravity waves. It is shown in particular that the wave resistance
remains bounded as the velocity of the perturbation approches the minimun phase
speed, unlike what is predicted by the inviscid theory.Comment: Europhysics Letters, in pres
FUV and X-ray Observations of the Reverse Shock in the SMC SNR 1E 0102.2-7219
We present FUSE and XMM-Newton data for the reverse shock of the O-rich SNR
1E0102.2-7219 in the SMC. The FUSE observations cover three regions with
significantly different optical [O III] intensities, all associated with the
relatively bright part of the X-ray ring. Emission lines of O VI 1032, 1038 are
clearly detected in the FUSE spectra. By combining this O VI doublet emission
with the O VII triplet and O VIII Lyalpha fluxes from the XMM-Newton spectra
and assuming a non-equilibrium ionization model with a single ionization
timescale for the spectra, we are able to find a narrow range of temperatures
and ionization timescales that are consistent with the respective line ratios.
However, if we assume a plane-parallel shock model with a distribution of
ionization timescales, the O VI emission appears to be inconsistent with O VII
and O VIII in X-rays. We also analyze the total XMM-Newton EPIC-MOS 1/2 spectra
for the three regions. The X-ray spectra are dominated by strong emission lines
of O, Ne, and Mg, however, we detect an emission component that accounts for 14
- 25% of the flux and can be attributed to shocked ISM. We find that there is
no consistent set of values for the temperature and ionization timescale which
can explain the observed line ratios for O, Ne, and Mg. This would be
consistent with a structured distribution of the ejecta as the O, Ne, Mg would
have interacted with the reverse shock at different times.Comment: 28 pages, 5 figues, Fig. 1 as JPEG. To be published in ApJ (01 May
2006, v. 642, 1 issue
Predicting the knowledgeârecklessness distinction in the human brain
Criminal convictions require proof that a prohibited act was performed in a statutorily specified mental state. Different legal consequences, including greater punishments, are mandated for those who act in a state of knowledge, compared with a state of recklessness. Existing research, however, suggests people have trouble classifying defendants as knowing, rather than reckless, even when instructed on the relevant legal criteria. We used a machine-learning technique on brain imaging data to predict, with high accuracy, which mental state our participants were in. This predictive ability depended on both the magnitude of the risks and the amount of information about those risks possessed by the participants. Our results provide neural evidence of a detectable difference in the mental state of knowledge in contrast to recklessness and suggest, as a proof of principle, the possibility of inferring from brain data in which legally relevant category a person belongs. Some potential legal implications of this result are discussed
Creation of an incus recess for a middle-ear microphone using a drill or laser ablation : a comparison of equivalent noise level and middle ear transfer function
Purpose: Studies have assessed the trauma and change in hearing function from the use of otological drills on the ossicular chain, but not the effects of partial laser ablation of the incus. A study of the effectiveness of a novel middle-ear microphone for a cochlear implant, which required an incus recess for the microphone balltip, provided an opportunity to compare methods and inform a feasibility study of the microphone with patients.
Methods: We used laser Doppler vibrometry with an insert earphone and probe microphone in 23 ears from 14 fresh-frozen cadavers to measure the equivalent noise level at the tympanic membrane that would have led to the same stapes velocity as the creation of the incus recess.
Results: Drilling on the incus with a diamond burr created peak noise levels equivalent to 125.1â155.0 dB SPL at the tympanic membrane, whilst using the laser generated equivalent noise levels barely above the baseline level. The change in middle ear transfer function following drilling showed greater variability at high frequencies, but the change was not statistically significant in the three frequency bands tested. Conclusions: Whilst drilling resulted in substantially higher equivalent noise, we considered that the recess created by laser ablation was more likely to lead to movement of the microphone balltip, and therefore decrease performance or result in malfunction over time. For patients with greatly reduced residual hearing, the greater consistency from drilling the incus recess may outweigh the potential benefits of hearing preservation with laser ablation
Stiripentol in D ravet syndrome: Results of a retrospective U . S . study
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100157/1/epi12303.pd
Predicting plasticity in disordered solids from structural indicators
Amorphous solids lack long-range order. Therefore identifying structural
defects -- akin to dislocations in crystalline solids -- that carry plastic
flow in these systems remains a daunting challenge. By comparing many different
structural indicators in computational models of glasses, under a variety of
conditions we carefully assess which of these indicators are able to robustly
identify the structural defects responsible for plastic flow in amorphous
solids. We further demonstrate that the density of defects changes as a
function of material preparation and strain in a manner that is highly
correlated with the macroscopic material response. Our work represents an
important step towards predicting how and when an amorphous solid will fail
from its microscopic structure
The Perceptions on Male Circumcision as a Preventive Measure Against HIV Infection and Considerations in Scaling up of the Services: A Qualitative Study Among Police Officers in Dar es Salaam, Tanzania.
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In recent randomized controlled trials, male circumcision has been proven to complement the available biomedical interventions in decreasing HIV transmission from infected women to uninfected men. Consequently, Tanzania is striving to scale-up safe medical male circumcision to reduce HIV transmission. However, there is a need to investigate the perceptions of male circumcision in Tanzania using specific populations. The purpose of the present study was to assess the perceptions of male circumcision in a cohort of police officers that also served as a source of volunteers for a phase I/II HIV vaccine (HIVIS-03) trial in Dar es Salaam, Tanzania. In-depth interviews with 24 men and 10 women were conducted. Content analysis informed by the socio-ecological model was used to analyze the data. Informants perceived male circumcision as a health-promoting practice that may prevent HIV transmission and other sexually transmitted infections. They reported male circumcision promotes sexual pleasure, confidence and hygiene or sexual cleanliness. They added that it is a religious ritual and a cultural practice that enhances the recognition of manhood in the community. However, informants were concerned about the cost involved in male circumcision and cleanliness of instruments used in medical and traditional male circumcision. They also expressed confusion about the shame of undergoing circumcision at an advanced age and pain that could emanate after circumcision. The participants advocated for health policies that promote medical male circumcision at childhood, specifically along with the vaccination program. The perceived benefit of male circumcision as a preventive strategy to HIV and other sexually transmitted infections is important. However, there is a need to ensure that male circumcision is conducted under hygienic conditions. Integrating male circumcision service in the routine childhood vaccination program may increase its coverage at early childhood. The findings from this investigation provide contextual understanding that may assist in scaling-up male circumcision in Tanzania.\u
Observations of supercooling and frazil ice formation in the Laptev Sea coastal polynya
This paper examines a hydrographic response to the windâdriven coastal polynya activity over the southeastern Laptev Sea shelf for AprilâMay 2008, using a combination of Environmental Satellite (Envisat) advanced synthetic aperture radar (ASAR) and TerraSARâX satellite imagery, aerial photography, meteorological data, and SBEâ37 salinityâtemperatureâdepth and acoustic Doppler current profiler landâfast ice edgemoored instruments. When ASAR observed the strongest endâofâApril polynya event with frazil ice formation, the moored instruments showed maximal acoustical scattering within the surface mixed layer, and the seawater temperatures were either at or 0.02°C below freezing. We also find evidence of the persistent orizontal temperature and salinity gradients across the fast ice edge to have the signature of geostrophic flow adjustment as predicted by polynya models
The Biosurveillance Analytics Resource Directory (BARD): Facilitating the Use of Epidemiological Models for Infectious Disease Surveillance
Epidemiological modeling for infectious disease is important for disease management and its routine implementation needs to be facilitated through better description of models in an operational context. A standardized model characterization process that allows selection or making manual comparisons of available models and their results is currently lacking. A key need is a universal framework to facilitate model description and understanding of its features. Los Alamos National Laboratory (LANL) has developed a comprehensive framework that can be used to characterize an infectious disease model in an operational context. The framework was developed through a consensus among a panel of subject matter experts. In this paper, we describe the framework, its application to model characterization, and the development of the Biosurveillance Analytics Resource Directory (BARD; http://brd.bsvgateway.org/brd/), to facilitate the rapid selection of operational models for specific infectious/communicable diseases. We offer this framework and associated database to stakeholders of the infectious disease modeling field as a tool for standardizing model description and facilitating the use of epidemiological models
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