25,734 research outputs found
Infrared Dark Cloud Cores in the SCUBA Legacy Catalogue
We present an investigation of candidate Infrared Dark Cloud cores as
identified by Simon et al. (2006) located within the SCUBA Legacy Catalogue.
After applying a uniform noise cut to the Catalogue data we identify 154
Infrared Dark Cloud cores that were detected at 850um and 51 cores that were
not. We derive column densities for each core from their 8um extinction and
find that the IRDCs detected at 850um have higher column densities (a mean of
1.7x10^22 cm-2) compared to those cores not detected at 850um (a mean of
1.0x10^22 cm-2). Combined with sensitivity estimates, we suggest that the cores
not detected at 850um are low mass, low column density and low temperature
cores that are below the sensitivity limit of SCUBA at 850um. For a subsample
of the cores detected at 850um those contained within the MIPSGAL area) we find
that two thirds are associated with 24um sources. Cores not associated with
24um emission are either ``starless'' IRDC cores that perhaps have yet to form
stars, or contain low mass YSOs below the MIPSGAL detection limit. We see that
those ``starless'' IRDC cores and the IRDC cores associated with 24um emission
are drawn from the same column density population and are of similar mass. If
we then assume the cores without 24um embedded sources are at an earlier
evolutionary stage to cores with embedded objects we derive a statistical
lifetime for the quiescent phase of a few 10^3-10^4 years. Finally, we make
conservative predictions for the number of observed IRDCs that will be observed
by the Apex Telescope Galactic Plane Survey (ATLASGAL), the Herschel Infrared
Galactic Plane Survey (Hi-GAL), the JCMT Galactic Plane Survey (JPS) and the
SCUBA-2 ``All Sky'' Survey (SASSy).Comment: 18 pages, 3 tables, 10 figure
Characterisation of nicotine receptors on human peripheral blood mononuclear cells (PBMC)
“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1007/s00011-008-8171-xAim and objective: The aim of the work was to characterise the nAChRs on human PBMC. Method: PBMC were isolated from human blood buffy coats provided by the blood transfusion service and were used for radioligand binding studies with [3H]-nicotine. RT-PCR experiments were used to determine nAChR subunit expression while immunoblotting experiments were used to confirm that nAChR subunits identified by RT-PCR were translated into protein. Results: Binding studies suggested the presence of one binding site for (-)- nicotine on human peripheral blood lymphocytes. Competition studies showed that only (-)- nicotine, epibatidine and α-bungarotoxin, displaced radiolabelled nicotine from cells. RT-PCR studies demonstrated mRNA for α4, α5, α7, β1 and β2 nAChRs subunits in PBMC. Expression of mRNA for the a5 subunit of nAChR was observed in all lymphocyte samples tested. In contrast, the expression pattern of mRNAs for α4, α7, β1, and β2 mRNAs subunits of nAChRs, varied between samples. Western blot analysis showed that protein for α4, α5, and α7 and β2 nAChR subunits was expressed in most, but not all of the PBMC samples tested but some of the bands obtained were faint. Conclusion: The results obtained suggest that human PBMC contain nAChRs containing α4β2, α4β2α5, and/or α7 subunits.Peer reviewe
Rapid evaluation of ion thruster lifetime using optical emission spectroscopy
A major life-limiting phenomenon of electric thrusters is the sputter erosion of discharge chamber components. Thrusters for space propulsion are required to operate for extended periods of time, usually in excess of 10,000 hr. Lengthy and very costly life-tests in high-vacuum facilities have been required in the past to determine the erosion rates of thruster components. Alternative methods for determining erosion rates which can be performed in relatively short periods of time at considerably lower costs are studied. An attempt to relate optical emission intensity from an ion bombarded surface (screen grid) to the sputtering rate of that surface is made. The model used a kinetic steady-state (KSS) approach, balancing the rates of population and depopulation of ten low-lying excited states of the sputtered molybdenum atom (MoI) with those of the ground state to relate the spectral intensities of the various transitions of the MoI to the population densities. Once this is accomplished, the population density can be related to the sputtering rate of the target. Radiative and collisional modes of excitation and decay are considered. Since actual data has not been published for MoI excitation rate and decay constants, semiempirical equations are used. The calculated sputtering rate and intensity is compared to the measured intensity and sputtering rates of the 8 and 30 cm ion thrusters
Synthesis and characterisation of Fe<sub>6</sub> and Fe<sub>12</sub> clusters using bicine
Reaction of bicine {BicH3, N,N-bis(2-hydroxyethyl)glycine} with an Fe(III) oxo-centered pivalate triangle in MeCN in the presence of Et<sub>2</sub>NH yields [Et<sub>2</sub>NH<sub>2</sub>]<sub>2</sub>[Fe<sub>6</sub>O<sub>2</sub>(OH)<sub>2</sub>(Bic)<sub>2</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>8</sub>], which possesses an S = 5 ground state.
Changing the base to NaOMe produces [Fe<sub>12</sub>O<sub>4</sub>(Bic)<sub>4</sub>(HBic)<sub>4</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>8</sub>], which contains two Fe6 units bridged by the carboxylate arms from the bicine ligands. The complex displays strong antiferromagnetic coupling leading to an S = 0 ground state
A Generic Algorithm for IACT Optical Efficiency Calibration using Muons
Muons produced in Extensive Air Showers (EAS) generate ring-like images in
Imaging Atmospheric Cherenkov Telescopes when travelling near parallel to the
optical axis. From geometrical parameters of these images, the absolute amount
of light emitted may be calculated analytically. Comparing the amount of light
recorded in these images to expectation is a well established technique for
telescope optical efficiency calibration. However, this calculation is usually
performed under the assumption of an approximately circular telescope mirror.
The H.E.S.S. experiment entered its second phase in 2012, with the addition of
a fifth telescope with a non-circular 600m mirror. Due to the differing
mirror shape of this telescope to the original four H.E.S.S. telescopes,
adaptations to the standard muon calibration were required. We present a
generalised muon calibration procedure, adaptable to telescopes of differing
shapes and sizes, and demonstrate its performance on the H.E.S.S. II array.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherland
Misreporting Fundraising: How do Nonprofit Organizations Account for Telemarketing Campaigns?
The purpose of this study is to examine the frequency, determinants and implications of misreporting fundraising activities. We compare state telemarketing campaign reports with the associated information from nonprofits annual Form 990 filings to directly test nonprofits revenue and expense recognition policies. Our study indicates that smaller nonprofits, and those with less accounting sophistication, are more likely to inappropriately report telemarketing costs as a component of net revenues rather than as expenses. In addition, less monitored firms are more likely to report telemarketing campaign revenues net of expenses. Additionally, among those firms that do report telemarketing costs as expenses, we find that smaller firms, and those with relatively less officer compensation, are more likely to allocate telemarketing expenses to non-fundraising expense categories.This publication is Hauser Center Working Paper No. 37. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers
A Proton Magnetic Resonance Study of the Association of Lysozyme with Monosaccharide Inhibitors
It has been shown that the acetamido methyl protons of N-acetyl-d-glucosamine undergo a chemical shift to higher fields in their proton magnetic resonance spectrum when the inhibitor is bound to lysozyme. The observed chemical shift in the presence of the enzyme is different for the agr- and ß-anomeric forms of 2-acetamido-2-deoxy-d-glucopyranose indicating either a difference in the affinity of the anomeric forms for lysozyme or different magnetic environments for the methyl protons in their enzyme-bound state. That the agr- and ß-anomeric forms of GlcAc bind to lysozyme in a competitive fashion was indicated by observing the proton magnetic resonance spectra in the presence of 2-acetamido-d3-2-deoxy-agr-d-glucopyranose. The methyl glycosides, methyl-agr-GlcAc and methyl-ß-GlcAc, were also shown to bind competitively with both anomers of GlcAc. Quantitative analysis of the chemical shift data observed for the association of GlcAc with lysozyme was complicated by the mutarotation of GlcAc between its agr- and ß-anomeric forms. However, in the case of the methyl glucosides, where the conformation of each anomer is frozen, it was possible to analyze the chemical shift data in a straightforward manner, and the dissociation constant as well as the chemical shift of the acetamido methyl protons of the enzyme-inhibitor complex was determined for both anomers. The results indicate that the two anomers of methyl-GlcAc bind to lysozyme with slightly different affinities but that the acetamido methyl groups of both anomers experience identical magnetic environments in the enzyme-inhibitor complex
Potential for measuring the longitudinal and lateral profile of muons in TeV air showers with IACTs
Muons are copiously produced within hadronic extensive air showers (EAS)
occurring in the Earth's atmosphere, and are used by particle air shower
detectors as a means of identifying the primary cosmic ray which initiated the
EAS. Imaging Atmospheric Cherenkov Telescopes (IACTs), designed for the
detection of gamma-ray initiated EAS for the purposes of Very High Energy (VHE)
gamma-ray astronomy, are subject to a considerable background signal due to
hadronic EAS. Although hadronic EAS are typically rejected for gamma-ray
analysis purposes, single muons produced within such showers generate clearly
identifiable signals in IACTs and muon images are routinely retained and used
for calibration purposes. For IACT arrays operating with a stereoscopic
trigger, when a muon triggers one telescope, other telescopes in IACT arrays
usually detect the associated hadronic EAS. We demonstrate for the first time
the potential of IACT arrays for competitive measurements of the muon content
of air showers, their lateral distribution and longitudinal profile of
production slant heights in the TeV energy range. Such information can provide
useful input to hadronic interaction models.Comment: 15 pages, 11 figures, 2 tables, accepted for publication in
Astroparticle Physic
THE ARBOVIRUS SURVEILLANCE AND CONTROL PROGRAM IN OHIO, 1975 – 76
In 1975 Ohio experienced the largest epidemic of mosquito-borne encephalitis in its history. Four hundred and sixty-eight human cases (416 St. Louis [SLE] and 52 California [CE] occurred with 30 fatalities; one death was due to CE. The entire United States was hard hit (Illinois, 475; Indiana, 297; Mississippi, 210; Michigan, 20; Tennessee, 91; 30 others, 550 ) with 1816 SLE, 160 CE, 133, Western, and 3 Eastern encephalitis cases causing 150 fatalities. The cycle of mosquito-borne encephalitis in nature progresses as follows: A mosquito infected with virus feeds on a non-infected animal, such as a bird in the case of St. Louis encephalitis. In approximately 24 hours the bird begins circulating the virus in its blood stream. This situation is called viremia. The bird circulates virus in sufficient quantity to infect other non-infected mosquitoes for a period of approximately four days. The virus then leaves the blood stream, and the bird is no longer able to infect a mosquito. After a period of approximately 10 days the virus has in turn invaded all tissues in the mosquito including the salivary glands. From that time on this mosquito can, by biting, infect any non-immune vertebrate
THE ARBOVIRUS SURVEILLANCE AND CONTROL PROGRAM IN OHIO, 1975 – 76
In 1975 Ohio experienced the largest epidemic of mosquito-borne encephalitis in its history. Four hundred and sixty-eight human cases (416 St. Louis [SLE] and 52 California [CE] occurred with 30 fatalities; one death was due to CE. The entire United States was hard hit (Illinois, 475; Indiana, 297; Mississippi, 210; Michigan, 20; Tennessee, 91; 30 others, 550 ) with 1816 SLE, 160 CE, 133, Western, and 3 Eastern encephalitis cases causing 150 fatalities. The cycle of mosquito-borne encephalitis in nature progresses as follows: A mosquito infected with virus feeds on a non-infected animal, such as a bird in the case of St. Louis encephalitis. In approximately 24 hours the bird begins circulating the virus in its blood stream. This situation is called viremia. The bird circulates virus in sufficient quantity to infect other non-infected mosquitoes for a period of approximately four days. The virus then leaves the blood stream, and the bird is no longer able to infect a mosquito. After a period of approximately 10 days the virus has in turn invaded all tissues in the mosquito including the salivary glands. From that time on this mosquito can, by biting, infect any non-immune vertebrate
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