1,208 research outputs found
The JCMT Gould Belt Survey: the effect of molecular contamination in SCUBA-2 observations of Orion A
Thermal emission from cold dust grains in giant molecular clouds can be used
to probe the physical properties, such as density, temperature and emissivity
in star-forming regions. We present the SCUBA-2 shared-risk observations at 450
m and 850 m of the Orion A molecular cloud complex taken at the James
Clerk Maxwell Telescope (JCMT). Previous studies showed that molecular emission
lines can contribute significantly to the measured fluxes in those continuum
bands. We use the HARP CO J=3-2 integrated intensity map for Orion A in
order to evaluate the molecular line contamination and its effects on the
SCUBA-2 maps. With the corrected fluxes, we have obtained a new spectral index
map for the thermal emission of dust in the well-known integral-shaped
filament. Furthermore, we compare a sample of 33 sources, selected over the
Orion A molecular cloud complex for their high CO J=3-2 line
contamination, to 27 previously identified clumps in OMC-4. This allows us to
quantify the effect of line contamination on the ratio of 850 m to 450
m flux densities and how it modifies the deduced spectral index of
emissivity for the dust grains. We also show that at least one
Spitzer-identified protostellar core in OMC-5 has a CO J=3-2
contamination level of 16 %. Furthermore, we find the strongest contamination
level (44 %) towards a young star with disk near OMC-2. This work is part of
the JCMT Gould Belt Legacy Survey.Comment: 13 pages, 6 figures, Accepted for publication in Monthly Notices of
the Royal Astronomical Society (MNRAS
Two-divisibility of the coefficients of certain weakly holomorphic modular forms
We study a canonical basis for spaces of weakly holomorphic modular forms of
weights 12, 16, 18, 20, 22, and 26 on the full modular group. We prove a
relation between the Fourier coefficients of modular forms in this canonical
basis and a generalized Ramanujan tau-function, and use this to prove that
these Fourier coefficients are often highly divisible by 2.Comment: Corrected typos. To appear in the Ramanujan Journa
The JCMT Gould Belt Survey: the effect of molecular contamination in SCUBA-2 observations of Orion A
JOURThis is the final version of the article. It was first published by Oxford Journals for the Royal Astronomical Society via http://dx.doi.org/ 10.1093/mnras/stv3009Thermal emission from cold dust grains in giant molecular clouds can be used to probe the physical properties, such as density, temperature and emissivity in star-forming regions. We present the Submillimetre Common-User Bolometer Array (SCUBA-2) shared-risk observations at 450 and 850 μm of the Orion A molecular cloud complex taken at the James Clerk Maxwell Telescope (JCMT). Previous studies showed that molecular emission lines can contribute significantly to the measured fluxes in those continuum bands. We use the Heterodyne Array Receiver Programme 12CO J = 3-2 integrated intensity map for Orion A in order to evaluate the molecular line contamination and its effects on the SCUBA-2 maps. With the corrected fluxes, we have obtained a new spectral index α map for the thermal emission of dust in the well-known integral-shaped filament. Furthermore, we compare a sample of 33 sources, selected over the Orion A molecular cloud complex for their high 12CO J = 3-2 line contamination, to 27 previously identified clumps in OMC 4. This allows us to quantify the effect of line contamination on the ratio of 850-450 μm flux densities and how it modifies the deduced spectral index of emissivity β for the dust grains. We also show that at least one Spitzer-identified protostellar core in OMC 5 has a 12CO J = 3-2 contamination level of 16 per cent. Furthermore, we find the strongest contamination level (44 per cent) towards a young star with disc near OMC 2. This work is part of the JCMT Gould Belt Legacy Survey
Numerical simulation of "an American haboob"
A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land-atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High-resolution numerical models are required for accurate simulation of the small scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran Desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME-DREAM (Non-hydrostatic Mesoscale Model on E grid, Janjic et al., 2001; Dust REgional Atmospheric Model, Nickovic et al., 2001; Perez et al., 2006) with 4 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The scope of this paper is validation of the dust model performance, and not use of the model as a tool to investigate mechanisms related to the storm. Results demonstrate the potential technical capacity and availability of the relevant data to build an operational system for dust storm forecasting as a part of a warning system. Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (similar to 25 km), the model PM10 surface dust concentration reached similar to 2500 mu g m(-3), but underestimated the values measured by the PM10 stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health
Bayesian inference of population expansions in domestic bovines
The past population dynamics of four domestic and one wild species of bovine were estimated using Bayesian skyline plots, a coalescent Markov chain Monte Carlo method that does not require an assumed parametric model of demographic history. Four domestic species share a recent rapid population expansion not visible in the wild African buffalo (Syncerus caffer). The estimated timings of the expansions are consistent with the archaeological records of domestication
Epistasis and the sensitivity of phenotypic screens for beta thalassaemia
Genetic disorders of haemoglobin, particularly the sickle cell diseases and the alpha and beta thalassaemias, are the commonest inherited disorders worldwide. The majority of affected births occur in low-income and lower-middle income countries. Screening programmes are a vital tool to counter these haemoglobinopathies by: (i) identifying individual carriers and allowing them to make informed reproductive choices, and (ii) generating population level gene-frequency estimates, to help ensure the optimal allocation of public health resources. For both of these functions it is vital that the screen performed is suitably sensitive. One popular first-stage screening option to detect carriers of beta thalassaemia in low-income countries is the One Tube Osmotic Fragility Test (OTOFT). Here we introduce a population genetic framework within which to quantify the likely sensitivity and specificity of the OTOFT in different epidemiological contexts. We demonstrate that interactions between the carrier states for beta thalassaemia and alpha thalassaemia, glucose-6-phosphate dehydrogenase deficiency and Southeast Asian Ovalocytosis have the potential to reduce the sensitivity of OTOFTs for beta thalassaemia heterozygosity to below 70%. Our results therefore caution against the widespread application of OTOFTs in regions where these erythrocyte variants co-occur
The influence of single-nucleotide polymorphisms on overall survival and toxicity in cabazitaxel-treated patients with metastatic castration-resistant prostate cancer
Purpose: Cabazitaxel, used in patients with metastatic castration-resistant prostate cancer (mCRPC), is associated with adverse events which may require dose reductions or discontinuation of treatment. We investigated the potential association of single-nucleotide polymorphisms (SNPs) in genes encoding drug transporters and drug-metabolizing enzymes with cabazitaxel toxicity, overall survival (OS) and pharmacokinetics (PK). Methods: A total of 128 cabazitaxel-treated mCRPC patients, of whom prospectively collected data on toxicity and OS were available and 24 mCRPC patients with available cabazitaxel PK measurements, were genotyped using genomic DNA obtained from EDTA blood. The SLCO1B1 (388A > G; *1B; rs2306283 and 521 T > C; *5; rs4149056 and haplotype SLCO1B1*15), SLCO1B3 (334 T > G; rs4149117), CYP3A4 (*22; rs35599367), CYP3A5 (*3; rs776746), ABCB1 (3435C > T; rs1045642), and TUBB1 (57 + 87A > C; rs463312) SNPs were tested for their association with clinical and PK parameters by univariate/multivariate logistic regression, log-rank test, or Kruskal–Wallis test. Results: The SLCO1B1*15 haplotype was significantly associated with a lower incidence of leukopenia and neutropenia (p = 0.020 and p = 0.028, respectively). Patients harboring a homozygous variant for SLCO1B1*1B experienced higher rate ≥ grade 3 (p = 0.042). None of the SNPs were associated with pharmacokinetics or OS. Conclusions: In this study, SLCO1B1 (SLCO1B1*15 and SLCO1B1*1B) was associated with cabazitaxel-induced adverse events in mCRPC patients. As the associations were opposite to previous studies in other drugs and contradicted an underlying pharmacokinetic rationale, these findings are likely to be false-positive and would ideally be validated with even larger (pharmacokinetic) cohorts
The processes in SM and MSSM
We present the results of a complete analysis of the one loop electroweak
corrections to in the Standard (SM) and
the Minimal Supersymmetric Standard Model (MSSM). A special emphasis is put on
the high energy behaviour of the various helicity amplitudes and the way the
logarithmic structure is generated. The large magnitude of these effects, which
induce striking differences between the SM and MSSM cases at high energies,
offers the possibility of making global tests which could check the consistency
of these models, and even decide whether any additional new physics is
required.Comment: Short version (16 pages and 9 figures) of the paper hep-ph/0207273,
to appear in Phy.Rev.D. e-mail: [email protected]
Tripartite entanglement dynamics for atom in a two-mode nonlinear cavity
In this communication we introduce a new model which represents the
interaction between an atom and two fields injected simultaneously within a
cavity including the nonlinear couplers. By using the canonical transformation
the model can be regarded as a generalization of several well-known models. We
calculate and discuss entanglement between the tripartite system of one atom
and the two cavity modes. For a short interaction time, similarities between
the behavior based on our solution compared with the other simulation based on
a numerical linear algebra solution of the original Hamiltonian with truncated
Fock bases for each mode, is shown. For a specific value of the Kerr-like
medium defined in this letter, we find that the entanglement, as measured by
concurrence, may terminate abruptly in a finite time.Comment: 13 pages, 4 figure
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