7,320 research outputs found
The Magnetic Field in the central parsec of the Galaxy
We present a polarisation map of the warm dust emission from the minispiral
in the central parsec of the Galactic centre. The observations were made at a
wavelength of 12.5 microns with CanariCam mounted on the 10.4-m Gran Telescopio
Canarias. The magnetic field traced by the polarised emission from aligned dust
grains is consistent with previous observations, but the increased resolution
of the present data reveals considerably more information on the detailed
structure of the B field and its correspondence with the filamentary emission
seen in both mid-infrared continuum emission and free-free emission at cm
wavelengths. The magnetic field appears to be compressed and pushed by the
outflows from luminous stars in the Northern Arm, but it is not disordered by
them. We identify some magnetically coherent filaments that cross the Northern
Arm at a Position Angle of ~45 degrees, and which may trace orbits inclined to
the primary orientation of the Northern Arm and circumnuclear disk. In the
East-West bar, the magnetic fields implied by the polarization in the lower
intensity regions lie predominantly along the bar at a Position Angle of 130 -
140 degrees. In contrast to the Northern Arm, the brighter regions of the bar
tend to have lower degrees of polarization with a greater divergence in
position angle compared to the local diffuse emission. It appears that the
diffuse emission in the East-West bar traces the underlying field and that the
bright compact sources are unrelated objects presumably projected onto the bar
and with different field orientationsComment: 12 Pages, 5 figures, 1 Table. To be published in MNRA
Craniometric variation among Brazilian and Scottish populations: a physical anthropology approach
The present investigation intended to compare the craniometric variations of two samples of different nationalities (Brazilian and Scottish). Materials and methods: The Brazilian sample consisted of 100 modern complete skulls, including 53 female skulls and 47 male skulls, and the Scottish sample consisted of 100 historical skulls (61 males, 39 females) and 36 mandibles (24 males, 12 females). The cranial measurement protocol was composed of 40 measurements, 11 bilateral and 29 unilateral, and the measurement protocol of the mandible was composed of 15 measurements, with six that were bilateral and nine that were unique. The comparative analysis of the metric variability between the two samples was performed using the means and medians analysis, the t-test, the Wilcoxon test, and the coefficient of variance, with a significance level of 5%. Results: The results showed that, among the 72 analysed variables, 44 measurements (61.11%) presented statistical differences between the samples. The Scottish skull tends to have a cranial length (GOL diff=5.53), breadth (XCB diff=3.78) and height (NPH diff=5.33) greater than the Brazilian skulls, and the Scottish mandibles tend to show a higher mandibular ramus height (MRH diff=9.25), a higher mandibular body height (HMB diff=6.37) and a larger bigonial breadth (BGB diff=5.29) than the Brazilians. The discriminant analysis of the 51 cranial measurements and 21 mandibular measurements showed a variation of the percentage of accuracy between 46.3- 83.8%. Conclusion: The metric analysis demonstrated that there is variability between the two samples studied (61.11%), but a concrete cause cannot be determined considering the multifactorial aspects of the variations of form and size
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NMHCs and halocarbons in Asian continental outflow during the Transport and Chemical Evolution over the Pacific (TRACE-P) Field Campaign: Comparison with PEM-West B
We present an overview of the spatial distributions of nonmethane hydrocarbons (NMHCs) and halocarbons observed over the western north Pacific as part of the NASA GTE Transport and Chemical Evolution over the Pacific (TRACE‐P) airborne field campaign (February–April 2001). The TRACE‐P data are compared with earlier measurements from the Pacific Rim during the Pacific Exploratory Mission‐West B (PEM‐West B), which took place in February–March 1994, and with emission inventory data for 2000. Despite the limited spatial and temporal data coverage inherent to airborne sampling, mean levels of the longer‐lived NMHCs (including ethane, ethyne, and benzene) were remarkably similar to our results during the PEM‐West B campaign. By comparison, mixing ratios of the fire extinguisher Halon‐1211 (CF2ClBr) increased by about 50% in the period between 1994 and 2001. Southern China (south of 35°N), and particularly the Shanghai region, appears to have been a substantial source of Halon‐1211 during TRACE‐P. Our previous analysis of the PEM‐West B data employed methyl chloroform (CH3CCl3) as a useful industrial tracer. However, regulations have reduced its emissions to the extent that its mixing ratio during TRACE‐P was only one‐third of that measured in 1994. Methyl chloroform mixing ratio “hot spots,” indicating regions downwind of continuing emissions, included outflow from the vicinity of Shanghai, China, but particularly high emission ratios relative to CO were observed close to Japan and Korea. Tetrachloroethene (C2Cl4) levels have also decreased significantly, especially north of 25°N, but this gas still remains a useful indicator of northern industrial emissions. Methyl bromide (CH3Br) levels were systematically 1–2 pptv lower from 1994 to 2001, in accord with recent reports. However, air masses that had been advected over Japan and/or South Korean port cities typically exhibited elevated levels of CH3Br. As a consequence, emissions of CH3Br from Japan and Korea calculated employing CH3Br/CO ratios and scaled to CO emission inventory estimates, were almost as large as for all of south China (south of 35°N). Total east Asian emissions of CH3Br and CH3Cl were estimated to be roughly 4.7 Gg/yr and 167 Gg/yr, respectively, in 2001
Parsec-scale jets driven by high-mass young stellar objects. Connecting the au- and the parsec-scale jet in IRAS 13481-6124
This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this recordR.F. acknowledges support from Science Foundation
Ireland (grant 13/ERC/12907). A.C.G. and T.P.R. have received funding
from the European Research Council (ERC) under the European Union’s Horizon
2020 research and innovation programme (grant agreement No. 743029).
R.G.L has received funding from the European Union’s Horizon 2020 research
and innovation programme under the Marie Skłodowska-Curie Grant (agreement
No. 706320). S.K. acknowledges support from an STFC Rutherford Fellowship
(ST/J004030/1) and ERC Starting Grant (Grant Agreement No. 639889)
Host genetic factors associated with hepatocellular carcinoma in patients with hepatitis C virus infection: a systematic review
Hepatitis C virus (HCV)-infected patients are at risk of developing hepatocellular carcinoma (HCC). Individuals at heightened riskcould be targeted by intensive follow-up surveillance. We have conducted a systematic review of the literature to identify host genetic predisposition to HCC in HCV-infected patients.
A comprehensive search of Medline and Embase databases was performed and the strength of evidence of associations for each gene on development of HCC was evaluated.
We identified 166 relevant studies, relating to 137 different genes, or combinations thereof. 17 genes were classified as having “good” evidence of an association, a significant association was observed for 37 genes but this finding had not yet been replicated, 56 genes had mixed or limited evidence of an association, and 27 genes showed no association. IFNL3/4, TNF-α and PNPLA3 genes had the most evidence of an association. There was, however, considerable heterogeneity in study design and data quality.
In conclusion, we identified a number of genes with evidence of association with HCC, but also a need for more standardised approaches to address this clinically critical question. It is important to consider the underlying mechanism of these relationships and which are confounded by the presence of other HCC risk factors and response to therapy. We also identified many genes where the evidence of association is contradictory or requires replication, as well as a number where associations have been studied but no evidence found. These findings should help to direct future studies on host genetic predisposition to HCC in patients with HCV infection
Malignant melanoma of the mandibular gingiva
Oral malignant melanoma is an infrequent neoplasia making up less than 1% of all melanomas, which exhibits much more aggressive behavior than those found on the skin. We present an aggressive case of oral malignant melanoma located on the mandibular gingiva in a 24-year-old male patient, who developed metastases to not only the regional lymph nodes but also the lungs and liver. The advanced stage of the disease contraindicated any surgical intervention and palliative chemotherapy was planned
A QM/MM approach for the study of monolayer-protected gold clusters
We report the development and implementation of hybrid methods that combine
quantum mechanics (QM) with molecular mechanics (MM) to theoretically
characterize thiolated gold clusters. We use, as training systems, structures
such as Au25(SCH2-R)18 and Au38(SCH2-R)24, which can be readily compared with
recent crystallographic data. We envision that such an approach will lead to an
accurate description of key structural and electronic signatures at a fraction
of the cost of a full quantum chemical treatment. As an example, we demonstrate
that calculations of the 1H and 13C NMR shielding constants with our proposed
QM/MM model maintain the qualitative features of a full DFT calculation, with
an order-of-magnitude increase in computational efficiency.Comment: Journal of Materials Science, 201
Alterations in Mesenteric Lymph Node T Cell Phenotype and Cytokine Secretion are Associated with Changes in Thymocyte Phenotype after LP-BM5 Retrovirus Infection
In this study, mouse MLN cells and thymocytes from advanced stages of
LP-BM5 retrovirus infection were studied. A decrease in
the percentage of IL-7+
cells and an increase in the percentage of IL-16+ cells in the MLN
indicated that
secretion of these cytokines was also altered after LP-BM5 infection. The
percentage of MLN T cells expressing IL-7 receptors was significantly reduced,
while the percentage of MLN T cells expressing TNFR-p75 and of B cells
expressing TNFR-p55 increased. Simultaneous analysis of surface markers and
cytokine secretion was done in an attempt to understand whether the deregulation
of IFN-Υ secretion could be ascribed to a defined cell phenotype, concluding
that
all T cell subsets studied increased IFN-Υ secretion after retrovirus infection.
Finally,
thymocyte phenotype was further analyzed trying to correlate changes in thymocyte
phenotype with MLN cell phenotype. The results indicated that the increase in
single positive either CD4+CD8- or CD4-
CD8+ cells was due to accumulation of
both immature (CD3- ) and mature (CD3+) single
positive thymocytes. Moreover,
single positive mature thymocytes presented a phenotype similar to the phenotype
previously seen on MLN T cells. In summary, we can conclude that LP-BM5 uses
the immune system to reach the thymus where it interferes with the generation of
functionally mature T cells, favoring the development of T cells with an abnormal
phenotype. These new T cells are activated to secrete several cytokines that in turn
will favor retrovirus
replication and inhibit any attempt of the immune system to control infection
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