3,414 research outputs found
Cost-effectiveness of Antiviral Stockpiling and Near-Patient Testing for Potential Influenza Pandemic
Storing sufficient antiviral drugs to treat all patients with clinical cases is cost-effective
Extended Huckel theory for bandstructure, chemistry, and transport. II. Silicon
In this second paper, we develop transferable semi-empirical parameters for
the technologically important material, silicon, using Extended Huckel Theory
(EHT) to calculate its electronic structure. The EHT-parameters areoptimized to
experimental target values of the band dispersion of bulk-silicon. We obtain a
very good quantitative match to the bandstructure characteristics such as
bandedges and effective masses, which are competitive with the values obtained
within an orthogonal-tight binding model for silicon. The
transferability of the parameters is investigated applying them to different
physical and chemical environments by calculating the bandstructure of two
reconstructed surfaces with different orientations: Si(100) (2x1) and Si(111)
(2x1). The reproduced - and -surface bands agree in part
quantitatively with DFT-GW calculations and PES/IPES experiments demonstrating
their robustness to environmental changes. We further apply the silicon
parameters to describe the 1D band dispersion of a unrelaxed rectangular
silicon nanowire (SiNW) and demonstrate the EHT-approach of surface passivation
using hydrogen. Our EHT-parameters thus provide a quantitative model of
bulk-silicon and silicon-based materials such as contacts and surfaces, which
are essential ingredients towards a quantitative quantum transport simulation
through silicon-based heterostructures.Comment: 9 pages, 9 figure
A suspected virus infection of the oral mucosa in Swedish reindeer (Rangifer tarandus L)
In 1980 a rather high frequency of reindeer, supplementarily fed in pens, were taken ill and deaths occurred as well. In five out of eight carcasses necrophsied oral lesions were observed. Histologically the mucosa, surrounding these lesions, was charasterized by the presence of intracytoplasmic inclusion bodies, inter- and intracellular oedema and vesicle formation. Fusobacterium necrophorum, Coll, betahaemolizing streptococci, and Cory neb acterium pyogenes found in the lesions were all considered secondary invaders. Serological samples from disease stricken herds were tested for antibodies against BVD-, P13-, and IBR-virus as well as Chlamydia. Low positive titres were observed but for BVDV. The result indicates that a thus far unidentified virus might be the primary cause of this enzootically occurring disease
Sonographic fetal biometry charts for a Pakistani cohort.
This study aimed to develop growth centiles at different gestational weeks for fetal biparietal diameter, abdominal circumference, femur length and head circumference in a Pakistani cohort. Data were collected at a tertiary referral hospital from pregnant women at gestational ages 13-40 weeks referred for obstetric ultrasound as a part of routine antenatal care. A total of 1599 fetal sonographic biometric measurements were collected after screening for the inclusion criteria. For each measurement, separate regression models were derived to estimate the mean, standard deviation and reference percentiles at each week of gestational age for this cohort. The best fitting model for each variable was selected. These charts will help radiologists and clinicians in predicting dates of delivery, assessing fetal growth and identifying intrauterine fetal insufficiency in the Pakistani population
Mass Profiles of the Typical Relaxed Galaxy Clusters A2199 and A496
We present maps and radial profiles of the gas temperature in the nearby
galaxy clusters A2199 and A496, which have the most accurate ASCA spectral data
for all hot clusters. These clusters are relaxed and can provide reliable X-ray
mass measurements under the assumption of hydrostatic equilibrium. The cluster
average temperatures corrected for the presence of cooling flows are 4.8+-0.2
keV and 4.7+-0.2 keV (90% errors), respectively. Outside the central cooling
flow regions, the radial temperature profiles are similar to those of the
majority of nearby relaxed clusters. They are accurately described by
polytropic models with gamma=1.17+-0.07 for A2199 and gamma=1.24+-0.09 for
A496. We use these polytropic models to derive accurate total mass profiles.
Within r=0.5/h Mpc, which corresponds to a radius of overdensity 1000, the
total mass values are 1.45+-0.15 10^14 /h Msun and 1.55+-0.15 10^14 /h Msun.
These values are 10% lower than those obtained assuming constant temperature.
The values inside a gas core radius (0.07-0.13/h Mpc) are a factor of >1.5
higher than the isothermal values. The gas mass fraction increases with radius
(by a factor of 3 between the X-ray core radius and r_1000) and at r_1000
reaches values of 0.057+-0.005 and 0.056+-0.006 h^-3/2 for the two clusters,
respectively. Our mass profiles within r_1000 are remarkably well approximated
by the NFW "universal" profile. Since A2199 and A496 are typical relaxed
clusters, the above findings should be relevant for most such systems. In
particular, the similarity of the temperature profiles in nearby clusters
appears to reflect the underlying "universal" dark matter profile. The upward
revision of mass at small radii will resolve most of the discrepancy between
the X-ray and strong lensing mass estimates. (Abridged)Comment: Latex, 9 pages, 6 figures, uses emulateapj.sty. Submitted to Ap
Chromosomal control of non-gliadin proteins from the 70% ethanol extract of wheat endosperm
The non-gliadin fraction of the 70% ethanol extracts of compensated nulli-tetrasomics and ditelosomics of Triticum aestivum cv. Chinese Spring has been analyzed by combined electrofocusing and electrophoresis. Seventeen of the 21 protein map components of the euploid have been ascribed to eight chromosomes: 4A, 3BS, 6BS, 7BS, 3D, 4D, 5D and 7DS.
The relationship of the different map components with other proteins previously associated with the same chromosomes is discusse
Protein complex directs hemoglobin-to-hemozoin formation in Plasmodium falciparum
Malaria parasites use hemoglobin (Hb) as a major nutrient source in the intraerythrocytic stage, during which heme is converted to hemozoin (Hz). The formation of Hz is essential for parasite survival, but to date, the underlying mechanisms of Hb degradation and Hz formation are poorly understood. We report the presence of a ∼200-kDa protein complex in the food vacuole that is required for Hb degradation and Hz formation. This complex contains several parasite proteins, including falcipain 2/2', plasmepsin II, plasmepsin IV, histo aspartic protease, and heme detoxification protein. The association of these proteins is evident from coimmunoprecipitation followed by mass spectrometry, coelution from a gel filtration column, cosedimentation on a glycerol gradient, and in vitro protein interaction analyses. To functionally characterize this complex, we developed an in vitro assay using two of the proteins present in the complex. Our results show that falcipain 2 and heme detoxification protein associate with each other to efficiently convert Hb to Hz. We also used this in vitro assay to elucidate the modes of action of chloroquine and artemisinin. Our results reveal that both chloroquine and artemisinin act during the heme polymerization step, and chloroquine also acts at the Hb degradation step. These results may have important implications in the development of previously undefined antimalarials
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