6,045 research outputs found
Pathologic manifestations of levamisole-adulterated cocaine exposure.
UnlabelledRheumatic manifestations of cocaine have been well described, but more recently, a dramatic increase in the levamisole-adulterated cocaine supply in the United States has disclosed unique pathologic consequences that are distinct from pure cocaine use. Most notably, patients show skin lesions and renal dysfunction in the setting of extremely high perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA). Unexpectedly, antibodies to myeloperoxidase, the typical target of p-ANCA, are relatively low if at all present. This discrepancy is due to the fact that p-ANCA seen in association with levamisole-adulterated cocaine exposure is often directed against atypical p-ANCA-associated antigens within the neutrophil granules such as human neutrophil elastase, lactoferrin, and cathepsin G. Biopsies of the skin lesions reveal leukocytoclastic vasculitis often involving both superficial and deep dermal vessels. Renal injury most typically manifests as crescentic and necrotizing pauci-immune glomerulonephritis. In this review, the manifestations of levamisole-adulterated cocaine-induced vasculitis are discussed with an emphasis on the typical histomorphologic findings seen on biopsy.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1764738711370019
Expert systems for automated maintenance of a Mars oxygen production system
A prototype expert system was developed for maintaining autonomous operation of a Mars oxygen production system. Normal operation conditions and failure modes according to certain desired criteria are tested and identified. Several schemes for failure detection and isolation using forward chaining, backward chaining, knowledge-based and rule-based are devised to perform several housekeeping functions. These functions include self-health checkout, an emergency shut down program, fault detection and conventional control activities. An effort was made to derive the dynamic model of the system using Bond-Graph technique in order to develop the model-based failure detection and isolation scheme by estimation method. Finally, computer simulations and experimental results demonstrated the feasibility of the expert system and a preliminary reliability analysis for the oxygen production system is also provided
Observed albedo decrease related to the spring snow retreat
We study the impact of the spring snow retreat on albedo from 1979 to 1991 using the ultraviolet (UV) reflectivity measured by the Total Ozone Mapping Spectrometer (TOMS). Over the Northern Hemisphere (NH) snowy land area that was snow covered at least once during this period, we find a 1.5% decrease over the 13 years in the springtime UV reflectivity, related to a 5 × 10^6km^² decrease in the satellite derived spring snow cover. About half of the reflectance decrease occurred over regions where snow cover and reflectance correlate at a 99% significance level. The 1.5% UV reflectivity decrease corresponds to a 1% decrease in the visible albedo over the snowy region, and a ∼2 Wm^(−2) increase in the shortwave heating when averaged over the entire NH land. Based on observed interannual reflectivity changes over the entire NH snowy land area, our study provides a direct constraint on the shortwave forcing of the spring NH snow retreat
Reflectivity variations off the Peru Coast: Evidence for indirect effect of anthropogenic sulfate aerosols on clouds
Using reflectivity measurements from the Total Ozone Mapping Spectrometer (TOMS), we show that over the months when stratocumulus clouds are prominent off the Peru Coast, the ultraviolet (UV) reflectance of two marine sites is consistently higher than that of the surroundings. The regions of reflectivity enhancement coincide with large anthropogenic sulfate aerosol emission sources, and the magnitude of the enhancement has a strong seasonal dependence that is related to the seasonal cloud movement. We propose the indirect aerosol effect as a plausible explanation for the reflectivity observations
Remarks on the stability of the Navier-Stokes equations supplemented with stress-free boundary conditions
The purpose of this note is to analyze the long term stability of the
Navier-Stokes equations supplemented with the Coriolis force and the
stress-free boundary condition. It is shown that, if the flow domain is
axisymmetric, spurious stability behaviors can occur depending whether the
Coriolis force is active or not
Phase-Dependent Spontaneous Spin Polarization and Bifurcation Delay in Coupled Two-Component Bose-Einstein Condensates
The spontaneous spin polarization and bifurcation delay in two-component
Bose-Einstein condensates coupled with laser or/and radio-frequency pulses are
investigated. We find that the bifurcation and the spontaneous spin
polarization are determined by both physical parameters and relative phase
between two condensates. Through bifurcations, the system enters into the
spontaneous spin polarization regime from the Rabi regime. We also find that
bifurcation delay appears when the parameter is swept through a static
bifurcation point. This bifurcation delay is responsible for metastability
leading to hysteresis.Comment: Improved version for cond-mat/021157
Intermittent electron density and temperature fluctuations and associated fluxes in the Alcator C-Mod scrape-off layer
The Alcator C-Mod mirror Langmuir probe system has been used to sample data
time series of fluctuating plasma parameters in the outboard mid-plane far
scrape-off layer. We present a statistical analysis of one second long time
series of electron density, temperature, radial electric drift velocity and the
corresponding particle and electron heat fluxes. These are sampled during
stationary plasma conditions in an ohmically heated, lower single null diverted
discharge.
The electron density and temperature are strongly correlated and feature
fluctuation statistics similar to the ion saturation current. Both electron
density and temperature time series are dominated by intermittent,
large-amplitude burst with an exponential distribution of both burst amplitudes
and waiting times between them.
The characteristic time scale of the large-amplitude bursts is approximately
15{\mu}s. Large-amplitude velocity fluctuations feature a slightly faster
characteristic time scale and appear at a faster rate than electron density and
temperature fluctuations.
Describing these time series as a superposition of uncorrelated exponential
pulses, we find that probability distribution functions, power spectral
densities as well as auto-correlation functions of the data time series agree
well with predictions from the stochastic model.
The electron particle and heat fluxes present large-amplitude fluctuations.
For this low-density plasma, the radial electron heat flux is dominated by
convection, that is, correlations of fluctuations in the electron density and
radial velocity. Hot and dense blobs contribute approximately 6% of the total
fluctuation driven heat flux
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