3,534 research outputs found
A CGPS Look at the Spiral Structure of the Outer Milky Way. I. Distances and Velocities to Star-Forming Regions
articleWe present a new catalog of spectrophotometric distances and line of sight systemic velocities to 103 H II regions
between 90≤ℓ≤195 (longitude quadrants II and part of III). Two new velocities for each region are
independently measured using 1 arcmin resolution 21 cm H I and 2.6 mm 12CO line maps (from the Canadian
Galactic Plane Survey and Five College Radio Astronomy Observatory Outer Galaxy Surveys) that show where
gaseous shells are observed around the periphery of the ionized gas. Known and neighboring O- and B-type stars
with published UBV photometry and MK classifications are overlaid onto 21 cm continuum maps, and those stars
observed within the boundary of the H II emission (and whose distance is not more than three times the standard
deviation of the others) are used to calculate new mean stellar distances to each of the 103 nebulae. Using this
approach of excluding distance outliers from the mean distance to a group of many stars in each H II region lessens
the impact of anomalous reddening for certain individuals. The standard deviation of individual stellar distances in
a cluster is typically 20% per stellar distance, and the error in the mean distance to the cluster is typically ±10%.
Final mean distances of nine common objects with very long baseline interferometry parallax distances show a 1:1
correspondence. Further, comparison with previous catalogs of H II regions in these quadrants shows a 50%
reduction in scatter for the distance to Perseus spiral arm objects in the same region, and a reduction by ∼1/ 2 in
scatter around a common angular velocity relative to the Sun W-W0(km s−1 kpc−1
). The purpose of the catalog is
to provide a foundation for more detailed large-scale Galactic spiral structure and dynamics (rotation curve, density
wave streaming) studies in the 2nd and 3rd quadrants, which from the Sun’s location is the most favorably viewed
section of the GalaxyWe thank the referees for their careful reading of and
thoughtful comments on our manuscript. The Dominion Radio
Astrophysical Observatory is operated as a national facility by
the National Research Council of Canada. The Canadian
Galactic Plane Survey has been a Canadian project with
international partners, and was supported by grants from the
Natural Sciences and Engineering Research Council of Canada
(NSERC). The Five College Radio Astronomy Observatory
was supported by NSF grant AST 0540852. T.F. has been
supported by an NSERC Discovery grant and a Brandon
University Research Committee Grant. C.B. is funded in part
by the UK Science and Technology Facilities Council grant
ST/J001627/1 (“From Molecular Clouds to Exoplanets”) and
the ERC grant ERC-2011-StG_20101014 (“LOCALSTAR”),
both held at the University of Exeter
Bone mineral density optimisation in adults with perinatally acquired HIV infection in routine care
We report on BMD and factors associated with reductions in BMD for all adults with perinatally acquired HIV who attended a London clinic between May 2014 and October 2016. We observed a high prevalence of reductions in BMD and a higher than expected prevalence of factors associated with adverse bone health, namely vitamin D deficiency
Experimental Investigation of Reinforced Concrete T-Beams Strengthened in Shear with Externally Bonded CFRP Sheets
An experimental investigation was undertaken into the effectiveness of unanchored and anchored externally bonded (EB) U-wrapped carbon fibre reinforced polymer (CFRP) shear strengthening for reinforced concrete T-beams at a range of realistic sizes. The T-beam sizes, geometry and reinforcement were chosen to reflect existing slab-on-beam structures with low levels of transverse steel shear reinforcement. Geometrically similar reinforced concrete T-beams were tested across three sizes ranging from 360 to 720 mm in depth and with different amounts of EB CFRP shear reinforcement. The beams were subjected to three-point bending with a span to depth ratio of 3.5. All the beams failed in diagonal shear. The experimental results indicate significant variability in the capacity of unstrengthened control beams, and a number of these control beams showed greater shear capacity than their EB CFRP strengthened counterparts. Greater thicknesses of CFRP reinforcement did not lead to increased shear capacity compared with lesser thicknesses of unanchored or anchored EB CFRP, but anchored EB CFRP did lead to moderate increases in shear capacity compared to both control and unanchored EB CFRP strengthened beams.The authors gratefully acknowledge the help of the laboratory staff of University of Bath and University of Cambridge. The authors would also like to acknowledge the financial support of: the UK Engineering and Physical Sciences Research Council (under grants EPSRC EP/I018921/1 and EP/I018972/1); the Universities of Bath and Cambridge; and the project partners and sponsors – Parsons Brinckerhoff, Tony Gee and Partners LLP, Arup, Highways
England, Concrete Repairs Ltd, LG Mouchel and Partners, The Concrete Society, Fyfe Europe S.A., Fibrwrap UK, Hughes Brothers and Ebor Concrete Ltd.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by ASCE
Variations of training load, monotony, and strain and dose-response relationships with maximal aerobic speed, maximal oxygen uptake, and isokinetic strength in professional soccer players
This study aimed to identify variations in weekly training load, training monotony, and training strain across a 10-week period (during both, pre- and in-season phases); and to analyze the dose-response relationships between training markers and maximal aerobic speed (MAS), maximal oxygen uptake, and isokinetic strength. Twenty-seven professional soccer players (24.9±3.5 years old) were monitored across the 10-week period using global positioning system units. Players were also tested for maximal aerobic speed, maximal oxygen uptake, and isokinetic strength before and after 10 weeks of training. Large positive correlations were found between sum of training load and extension peak torque in the right lower limb (r = 0.57, 90%CI[0.15;0.82]) and the ratio agonist/antagonist in the right lower limb (r = 0.51, [0.06;0.78]). It was observed that loading measures fluctuated across the period of the study and that the load was meaningfully associated with changes in the fitness status of players. However, those magnitudes of correlations were small-to-large, suggesting that variations in fitness level cannot be exclusively explained by the accumulated load and loading profile
Cross-polarized photon-pair generation and bi-chromatically pumped optical parametric oscillation on a chip
Nonlinear optical processes are one of the most important tools in modern optics with a broad spectrum of applications in, for example, frequency conversion, spectroscopy, signal processing and quantum optics. For practical and ultimately widespread implementation, on-chip devices compatible with electronic integrated circuit technology offer great advantages in terms of low cost, small footprint, high performance and low energy consumption. While many on-chip key components have been realized, to date polarization has not been fully exploited as a degree of freedom for integrated nonlinear devices. In particular, frequency conversion based on orthogonally polarized beams has not yet been demonstrated on chip. Here we show frequency mixing between orthogonal polarization modes in a compact integrated microring resonator and demonstrate a bi-chromatically pumped optical parametric oscillator. Operating the device above and below threshold, we directly generate orthogonally polarized beams, as well as photon pairs, respectively, that can find applications, for example, in optical communication and quantum optics
Optical frequency comb generation from a monolithic microresonator
Optical frequency combs provide equidistant frequency markers in the
infrared, visible and ultra-violet and can link an unknown optical frequency to
a radio or microwave frequency reference. Since their inception frequency combs
have triggered major advances in optical frequency metrology and precision
measurements and in applications such as broadband laser-based gas sensing8 and
molecular fingerprinting. Early work generated frequency combs by intra-cavity
phase modulation while to date frequency combs are generated utilizing the
comb-like mode structure of mode-locked lasers, whose repetition rate and
carrier envelope phase can be stabilized. Here, we report an entirely novel
approach in which equally spaced frequency markers are generated from a
continuous wave (CW) pump laser of a known frequency interacting with the modes
of a monolithic high-Q microresonator13 via the Kerr nonlinearity. The
intrinsically broadband nature of parametric gain enables the generation of
discrete comb modes over a 500 nm wide span (ca. 70 THz) around 1550 nm without
relying on any external spectral broadening. Optical-heterodyne-based
measurements reveal that cascaded parametric interactions give rise to an
optical frequency comb, overcoming passive cavity dispersion. The uniformity of
the mode spacing has been verified to within a relative experimental precision
of 7.3*10(-18).Comment: Manuscript and Supplementary Informatio
TGF-beta 1 induces human alveolar epithelial to mesenchymal cell transition (EMT)
Background: Fibroblastic foci are characteristic features in lung parenchyma of patients with idiopathic pulmonary fibrosis (IPF). They comprise aggregates of mesenchymal cells which underlie sites of unresolved epithelial injury and are associated with progression of fibrosis. However, the cellular origins of these mesenchymal phenotypes remain unclear. We examined whether the potent fibrogenic cytokine TGF-β1 could induce epithelial mesenchymal transition (EMT) in the human alveolar epithelial cell line, A549, and investigated the signaling pathway of TGF-β1-mediated EMT.
Methods: A549 cells were examined for evidence of EMT after treatment with TGF-β1. EMT was assessed by: morphology under phase-contrast microscopy; Western analysis of cell lysates for expression of mesenchymal phenotypic markers including fibronectin EDA (Fn-EDA), and expression of epithelial phenotypic markers including E-cadherin (E-cad). Markers of fibrogenesis, including collagens and connective tissue growth factor (CTGF) were also evaluated by measuring mRNA level using RT-PCR, and protein by immunofluorescence or Western blotting. Signaling pathways for EMT were characterized by Western analysis of cell lysates using monoclonal antibodies to detect phosphorylated Erk1/2 and Smad2 after TGF-β1 treatment in the presence or absence of MEK inhibitors. The role of Smad2 in TGF-β1-mediated EMT was investigated using siRNA.
Results: The data showed that TGF-β1, but not TNF-α or IL-1β, induced A549 cells with an alveolar epithelial type II cell phenotype to undergo EMT in a time-and concentration-dependent manner. The process of EMT was accompanied by morphological alteration and expression of the fibroblast phenotypic markers Fn-EDA and vimentin, concomitant with a downregulation of the epithelial phenotype marker E-cad. Furthermore, cells that had undergone EMT showed enhanced expression of markers of fibrogenesis including collagens type I and III and CTGF. MMP-2 expression was also evidenced. TGF-β1-induced EMT occurred through phosphorylation of Smad2 and was inhibited by Smad2 gene silencing; MEK inhibitors failed to attenuate either EMT-associated Smad2 phosphorylation or the observed phenotypic changes.
Conclusion: Our study shows that TGF-β1 induces A549 alveolar epithelial cells to undergo EMT via Smad2 activation. Our data support the concept of EMT in lung epithelial cells, and suggest the need for further studies to investigate the phenomenon
Precision Measurement of the Newtonian Gravitational Constant Using Cold Atoms
About 300 experiments have tried to determine the value of the Newtonian
gravitational constant, G, so far, but large discrepancies in the results have
made it impossible to know its value precisely. The weakness of the
gravitational interaction and the impossibility of shielding the effects of
gravity make it very difficult to measure G while keeping systematic effects
under control. Most previous experiments performed were based on the torsion
pendulum or torsion balance scheme as in the experiment by Cavendish in 1798,
and in all cases macroscopic masses were used. Here we report the precise
determination of G using laser-cooled atoms and quantum interferometry. We
obtain the value G=6.67191(99) x 10^(-11) m^3 kg^(-1) s^(-2) with a relative
uncertainty of 150 parts per million (the combined standard uncertainty is
given in parentheses). Our value differs by 1.5 combined standard deviations
from the current recommended value of the Committee on Data for Science and
Technology. A conceptually different experiment such as ours helps to identify
the systematic errors that have proved elusive in previous experiments, thus
improving the confidence in the value of G. There is no definitive relationship
between G and the other fundamental constants, and there is no theoretical
prediction for its value, against which to test experimental results. Improving
the precision with which we know G has not only a pure metrological interest,
but is also important because of the key role that G has in theories of
gravitation, cosmology, particle physics and astrophysics and in geophysical
models.Comment: 3 figures, 1 tabl
The intestinal expulsion of the roundworm Ascaris suum is associated with eosinophils, intra-epithelial T cells and decreased intestinal transit time
Ascaris lumbricoides remains the most common endoparasite in humans, yet there is still very little information available about the immunological principles of protection, especially those directed against larval stages. Due to the natural host-parasite relationship, pigs infected with A. suum make an excellent model to study the mechanisms of protection against this nematode. In pigs, a self-cure reaction eliminates most larvae from the small intestine between 14 and 21 days post infection. In this study, we investigated the mucosal immune response leading to the expulsion of A. suum and the contribution of the hepato-tracheal migration. Self-cure was independent of previous passage through the liver or lungs, as infection with lung stage larvae did not impair self-cure. When animals were infected with 14-day-old intestinal larvae, the larvae were being driven distally in the small intestine around 7 days post infection but by 18 days post infection they re-inhabited the proximal part of the small intestine, indicating that more developed larvae can counter the expulsion mechanism. Self-cure was consistently associated with eosinophilia and intra-epithelial T cells in the jejunum. Furthermore, we identified increased gut movement as a possible mechanism of self-cure as the small intestinal transit time was markedly decreased at the time of expulsion of the worms. Taken together, these results shed new light on the mechanisms of self-cure that occur during A. suum infections
Murine model for Fusarium oxysporum invasive fusariosis reveals organ-specific structures for dissemination and long-term persistence
Peer reviewedPublisher PD
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