619 research outputs found
Fan Assessment Numeration System (FANS) Design and Calibration Specifications
A device for in-situ fan airflow measurement, called the Fan Assessment Numeration System (FANS) device, previously developed and constructed at the USDA-ARS Southern Poultry Research Laboratory, was refined at University of Kentucky as part of a project for quantifying building emissions from poultry and livestock operations. The FANS incorporates an array of five propeller anemometers to perform a real-time traverse of the air flow entering fans of up to 137 cm (54 in) diameter. Details of the updated design, including hardware, software, and calibration methodology are presented. An error analysis of the flow rate, and calibration results from ten units recently manufactured, is provided. Sufficient details of fabrication and calibration are presented so that interested readers can replicate a FANS for their use. Full design details are provided at www.bae.uky.edu/IFAFS/FANS
Entanglement in a Solid State Spin Ensemble
Entanglement is the quintessential quantum phenomenon and a necessary
ingredient in most emerging quantum technologies, including quantum repeaters,
quantum information processing (QIP) and the strongest forms of quantum
cryptography. Spin ensembles, such as those in liquid state nuclear magnetic
resonance, have been powerful in the development of quantum control methods,
however, these demonstrations contained no entanglement and ultimately
constitute classical simulations of quantum algorithms. Here we report the
on-demand generation of entanglement between an ensemble of electron and
nuclear spins in isotopically engineered phosphorus-doped silicon. We combined
high field/low temperature electron spin resonance (3.4 T, 2.9 K) with
hyperpolarisation of the 31P nuclear spin to obtain an initial state of
sufficient purity to create a non-classical, inseparable state. The state was
verified using density matrix tomography based on geometric phase gates, and
had a fidelity of 98% compared with the ideal state at this field and
temperature. The entanglement operation was performed simultaneously, with high
fidelity, to 10^10 spin pairs, and represents an essential requirement of a
silicon-based quantum information processor.Comment: 4 pages, 3 figures plus supporting information of 4 pages, 1 figure
v2: Updated reference
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Mechanisms and controlling characteristics of the catalytic oxidation of methane
Methane dissociation and oxygen activation have been found to be structure sensitive on different single crystal palladium surfaces. Geometrically restricted surfaces on Pd single crystal and polycrystalline surfaces using tetrachloroethylene and pentamethylcyclopentasiloxane have been formed and compared with surface structures formed using dichloromethane and chlorine. The adsorption and activation of O{sub 2}, CO, and H{sub 2}O on clean Pd surfaces and those containing the surface ensembles have also been investigated. To interpret high-resolution angle-resolved x-ray photoelectron spectra (HR AR-XPS), a new self-modeling method of resolving HR-XPS spectra was developed and applied to the experimental spectra. The effects of electron-accepting Cl, O{sub 2}, and H{sub 2}O adsobated on Cs/MoS{sub 2} were determined
Diffusion tensor imaging of Parkinson's disease, multiple system atrophy and progressive supranuclear palsy: a tract-based spatial statistics study
Although often clinically indistinguishable in the early stages, Parkinson's disease (PD), Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP) have distinct neuropathological changes. The aim of the current study was to identify white matter tract neurodegeneration characteristic of each of the three syndromes. Tract-based spatial statistics (TBSS) was used to perform a whole-brain automated analysis of diffusion tensor imaging (DTI) data to compare differences in fractional anisotropy (FA) and mean diffusivity (MD) between the three clinical groups and healthy control subjects. Further analyses were conducted to assess the relationship between these putative indices of white matter microstructure and clinical measures of disease severity and symptoms. In PSP, relative to controls, changes in DTI indices consistent with white matter tract degeneration were identified in the corpus callosum, corona radiata, corticospinal tract, superior longitudinal fasciculus, anterior thalamic radiation, superior cerebellar peduncle, medial lemniscus, retrolenticular and anterior limb of the internal capsule, cerebral peduncle and external capsule bilaterally, as well as the left posterior limb of the internal capsule and the right posterior thalamic radiation. MSA patients also displayed differences in the body of the corpus callosum corticospinal tract, cerebellar peduncle, medial lemniscus, anterior and superior corona radiata, posterior limb of the internal capsule external capsule and cerebral peduncle bilaterally, as well as the left anterior limb of the internal capsule and the left anterior thalamic radiation. No significant white matter abnormalities were observed in the PD group. Across groups, MD correlated positively with disease severity in all major white matter tracts. These results show widespread changes in white matter tracts in both PSP and MSA patients, even at a mid-point in the disease process, which are not found in patients with PD
The Parallel Magnetoconductance of Interacting Electrons in a Two Dimensional Disordered System
The transport properties of interacting electrons for which the spin degree
of freedom is taken into account are numerically studied for small two
dimensional diffusive clusters. On-site electron-electron interactions tend to
delocalize the electrons, while long-range interactions enhance localization.
On careful examination of the transport properties, we reach the conclusion
that it does not show a two dimensional metal insulator transition driven by
interactions. A parallel magnetic field leads to enhanced resistivity, which
saturates once the electrons become fully spin polarized. The strength of the
magnetic field for which the resistivity saturates decreases as electron
density goes down. Thus, the numerical calculations capture some of the
features seen in recent experimental measurements of parallel
magnetoconductance.Comment: 10 pages, 6 figure
Ezrin interacts with the SARS coronavirus spike protein and restrains infection at the entry stage
© 2012 Millet et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Entry of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and its envelope fusion with host cell membrane are controlled by a series of complex molecular mechanisms, largely dependent on the viral envelope glycoprotein Spike (S). There are still many unknowns on the implication of cellular factors that regulate the entry process. Methodology/Principal Findings: We performed a yeast two-hybrid screen using as bait the carboxy-terminal endodomain of S, which faces the cytosol during and after opening of the fusion pore at early stages of the virus life cycle. Here we show that the ezrin membrane-actin linker interacts with S endodomain through the F1 lobe of its FERM domain and that both the eight carboxy-terminal amino-acids and a membrane-proximal cysteine cluster of S endodomain are important for this interaction in vitro. Interestingly, we found that ezrin is present at the site of entry of S-pseudotyped lentiviral particles in Vero E6 cells. Targeting ezrin function by small interfering RNA increased S-mediated entry of pseudotyped particles in epithelial cells. Furthermore, deletion of the eight carboxy-terminal amino acids of S enhanced S-pseudotyped particles infection. Expression of the ezrin dominant negative FERM domain enhanced cell susceptibility to infection by SARS-CoV and S pseudotyped particles and potentiated S-dependent membrane fusion. Conclusions/Significance: Ezrin interacts with SARS-CoV S endodomain and limits virus entry and fusion. Our data present a novel mechanism involving a cellular factor in the regulation of S-dependent early events of infection.This work was supported by the Research Grant Council of Hong Kong (RGC#760208)and the RESPARI project of the International Network of Pasteur Institutes
Cortical thickness, surface area and volume measures in Parkinson's disease, multiple system atrophy and progressive supranuclear palsy
OBJECTIVE
Parkinson's disease (PD), Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP) are neurodegenerative diseases that can be difficult to distinguish clinically. The objective of the current study was to use surface-based analysis techniques to assess cortical thickness, surface area and grey matter volume to identify unique morphological patterns of cortical atrophy in PD, MSA and PSP and to relate these patterns of change to disease duration and clinical features.
METHODS
High resolution 3D T1-weighted MRI volumes were acquired from 14 PD patients, 18 MSA, 14 PSP and 19 healthy control participants. Cortical thickness, surface area and volume analyses were carried out using the automated surface-based analysis package FreeSurfer (version 5.1.0). Measures of disease severity and duration were assessed for correlation with cortical morphometric changes in each clinical group.
RESULTS
Results show that in PSP, widespread cortical thinning and volume loss occurs within the frontal lobe, particularly the superior frontal gyrus. In addition, PSP patients also displayed increased surface area in the pericalcarine. In comparison, PD and MSA did not display significant changes in cortical morphology.
CONCLUSION
These results demonstrate that patients with clinically established PSP exhibit distinct patterns of cortical atrophy, particularly affecting the frontal lobe. These results could be used in the future to develop a useful clinical application of MRI to distinguish PSP patients from PD and MSA patients
Field Longevity of a Fluorescent Protein Marker in an Engineered Strain of the Pink Bollworm, Pectinophora gossypiella (Saunders)
The cotton pest, pink bollworm (Pectinophora gossypiella (Saunders)), is a significant pest in most cotton-growing areas around the world. In southwestern USA and northern Mexico, pink bollworm is the target of the sterile insect technique (SIT), which relies on the mass-release of sterile pink bollworm adults to over-flood the wild population and thereby reduce it over time. Sterile moths reared for release are currently marked with a dye provided in their larval diet. There are concerns, however, that this marker fails from time to time, leading to sterile moths being misidentified in monitoring traps as wild moths. This can lead to expensive reactionary releases of sterile moths. We have developed a genetically marked strain that is engineered to express a fluorescent protein, DsRed2, which is easily screened under a specialised microscope. In order to test this marker under field conditions, we placed wild-type and genetically marked moths on traps and placed them in field cages. The moths were then screened, in a double-blind fashion, for DsRed2 fluorescence at regular intervals to determine marker reliability over time. The marker was shown to be robust in very high temperatures and generally proved reliable for a week or longer. More importantly, genotyping of moths on traps by PCR screening of the moths was 100% correct. Our findings indicate that this strain - and fluorescent protein markers in general - could make a valuable contribution to SIT
Rare B decays and Tevatron top-pair asymmetry
The recent Tevatron result on the top quark forward-backward asymmetry, which
deviates from its standard model prediction by 3.4, has prompted many
authors to build new models to account for this anomaly. Among the various
proposals, we find that those mechanisms which produce via - or
-channel can have a strong correlation to the rare B decays. We demonstrate
this link by studying a model with a new charged gauge boson, . In terms of
the current measurements on decays, we conclude that the branching
ratio for is affected most by the new effects.
Furthermore, using the world average branching ratio for the exclusive B decays
at level, we discuss the allowed values for the new parameters.
Finally, we point out that the influence of the new physics effects on the
direct CP asymmetry in B decays is insignificant.Comment: 15 page, 6 figures, typos corrected and references added, final
version to appear journa
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