8,540 research outputs found
Meteor showers of comet C/1917 F1 Mellish
December Monocerotids and November Orionids are weak but established annual
meteor showers active throughout November and December. Analysis of a high
quality orbits subset of the SonotaCo video meteor database shows that the
distribution of orbital elements, geocentric velocity and also the orbital
evolution of the meteors and potential parent body may imply a common origin
for these meteors coming from the parent comet C/1917 F1 Mellish. This is also
confirmed by the physical properties and activity of these shower meteors. An
assumed release of meteoroids at the perihelion of the comet in the past and
the sky-plane radiant distribution reveal that the December Monocerotid stream
might be younger than the November Orionids. A meteoroid transversal component
of ejection velocity at the perihelion must be larger than 100 m/s. A few
authors have also associated December Canis Minorids with the comet C/1917 F1
Mellish. However, we did not find any connection.Comment: 11 pages, 11 figures and 5 table
Higgsing M2 to D2 with gravity: N=6 chiral supergravity from topologically gauged ABJM theory
We present the higgsing of three-dimensional N=6 superconformal ABJM type
theories coupled to conformal supergravity, so called topologically gauged ABJM
theory, thus providing a gravitational extension of previous work on the
relation between N M2 and N D2-branes. The resulting N=6 supergravity theory
appears at a chiral point similar to that of three-dimensional chiral gravity
introduced recently by Li, Song and Strominger, but with the opposite sign for
the Ricci scalar term in the lagrangian. We identify the supersymmetry in the
broken phase as a particular linear combination of the supersymmetry and
special conformal supersymmetry in the original topologically gauged ABJM
theory. We also discuss the higgsing procedure in detail paying special
attention to the role played by the U(1) factors in the original ABJM model and
the U(1) introduced in the topological gauging.Comment: 53 pages, Late
Critical solutions in topologically gauged N=8 CFTs in three dimensions
In this paper we discuss some special (critical) background solutions that
arise in topological gauged three-dimensional CFTs with SO(N)
gauge group. These solutions solve the TMG equations (containing the parameters
and ) for a certain set of values of obtained by varying the
number of scalar fields with a VEV. Apart from Minkowski, chiral round
and null-warped (or Schr\"odinger(z=2)) we identify also a more exotic
solution recently found in by Ertl, Grumiller and Johansson. We also
discuss the spectrum, symmetry breaking pattern and the supermultiplet
structure in the various backgrounds and argue that some properties are due to
their common origin in a conformal phase. Some of the scalar fields, including
all higgsed ones, turn out to satisfy three-dimensional singleton field
equations. Finally, we note that topologically gauged ABJ(M)
theories have a similar, but more restricted, set of background solutions.Comment: 34 pages, v2: minor corrections, note about a new solution added in
final section, v3: two footnotes adde
Oral vs. pharyngeal dysphagia: surface electromyography randomized study
<p>Abstract</p> <p>Background</p> <p>A clear differential diagnosis between oral and pharyngeal dysphagia remains an unsolved problem. Disorders of the oral cavity are frequently overlooked when dysphagia/odybophagia complaints are assessed. Surface electromyographic (sEMG) studies were performed on randomly assigned patients with oral and pharyngeal pathology to evaluate their dysphagia complaints for the sake of differential diagnosis.</p> <p>Methods</p> <p>Parameters evaluated during swallowing for patients after dental surgery (1: n = 62), oral infections (2: n = 49), acute tonsillitis (3: n = 66) and healthy controls (4: n = 50) included timing and amplitude of sEMG activity of masseter, infrahyoid and submental muscles.</p> <p>Results</p> <p>The duration of swallows and drinking periods was significantly increased in dental patients and was normal in patients with tonsillitis. The electric activity of masseter was significantly lower in Groups 1 and 2 in comparison with the patients with tonsillitis and controls. The submental and infrahyoid activity was normal in dental patients but infrahyoid activity in patients with tonsillitis was high.</p> <p>Conclusion</p> <p>Dysphagia following dental surgery or oral infections does not affect pharynx and submental muscles and has clear sEMG signs: increased duration of a single swallow, longer drinking time, low activity of the masseter, and normal range of submental activity. Patients with tonsillitis present hyperactivity of infrahyoid muscles. These data could be used for evaluation of symptoms when differential dental/ENT diagnosis is needed.</p
Central Powering of the Largest Lyman-alpha Nebula is Revealed by Polarized Radiation
High-redshift Lyman-alpha blobs are extended, luminous, but rare structures
that appear to be associated with the highest peaks in the matter density of
the Universe. Their energy output and morphology are similar to powerful radio
galaxies, but the source of the luminosity is unclear. Some blobs are
associated with ultraviolet or infrared bright galaxies, suggesting an extreme
starburst event or accretion onto a central black hole. Another possibility is
gas that is shock excited by supernovae. However some blobs are not associated
with galaxies, and may instead be heated by gas falling into a dark matter
halo. The polarization of the Ly-alpha emission can in principle distinguish
between these options, but a previous attempt to detect this signature returned
a null detection. Here we report on the detection of polarized Ly-alpha from
the blob LAB1. Although the central region shows no measurable polarization,
the polarized fraction (P) increases to ~20 per cent at a radius of 45 kpc,
forming an almost complete polarized ring. The detection of polarized radiation
is inconsistent with the in situ production of Ly-alpha photons, and we
conclude that they must have been produced in the galaxies hosted within the
nebula, and re-scattered by neutral hydrogen.Comment: Published in the August 18 issue of Nature. 1750 words, 3 figures,
and full Supplementary Information. Version has not undergone proofing.
Reduced and processed data products are available here:
http://obswww.unige.ch/people/matthew.hayes/LymanAlpha/LabPol
Oestrogen receptor alpha in pulmonary hypertension
Aims Pulmonary arterial hypertension (PAH) occurs more frequently in women with mutations in bone morphogenetic protein receptor type 2 (BMPR2) and dysfunctional BMPR2 signalling underpinning heritable PAH. We have previously shown that serotonin can uncover a pulmonary hypertensive phenotype in BMPR2+/− mice and that oestrogen can increase serotinergic signalling in human pulmonary arterial smooth muscle cells (hPASMCs). Hence, here we wished to characterize the expression of oestrogen receptors (ERs) in male and female human pulmonary arteries and have examined the influence of oestrogen and serotonin on BMPR2 and ERα expression.
Methods and results: By immunohistochemistry, we showed that ERα, ERβ, and G-protein-coupled receptors are expressed in human pulmonary arteries localizing mainly to the smooth muscle layer which also expresses the serotonin transporter (SERT). Protein expression of ERα protein was higher in female PAH patient hPASMCs compared with male and serotonin also increased the expression of ERα. 17β-estradiol induced proliferation of hPASMCs via ERα activation and this engaged mitogen-activated protein kinase and Akt signalling. Female mice over-expressing SERT (SERT+ mice) develop PH and the ERα antagonist MPP attenuated the development of PH in normoxic and hypoxic female SERT+ mice. The therapeutic effects of MPP were accompanied by increased expression of BMPR2 in mouse lung.
Conclusion: ERα is highly expressed in female hPASMCs from PAH patients and mediates oestrogen-induced proliferation of hPASMCs via mitogen-activated protein kinase and Akt signalling. Serotonin can increase ERα expression in hPASMCs and antagonism of ERα reverses serotonin-dependent PH in the mouse and increases BMPR2 expression.</p
Vertical zonation of testate amoebae in the Elatia Mires, northern Greece : palaeoecological evidence for a wetland response to recent climate change or autogenic processes?
The Elatia Mires of northern Greece are unique ecosystems of high conservation value. The mires are climatically marginal and may be sensitive to changing hydroclimate, while northern Greece has experienced a significant increase in aridity since the late twentieth century. To investigate the impact of recent climatic change on the hydrology of the mires, the palaeoecological record was investigated from three near-surface monoliths extracted from two sites. Testate amoebae were analysed as sensitive indicators of hydrology. Results were interpreted using transfer function models to provide quantitative reconstructions of changing water table depth and pH. AMS radiocarbon dates and 210Pb suggest the peats were deposited within the last c. 50 years, but do not allow a secure chronology to be established. Results from all three profiles show a distinct shift towards a more xerophilic community particularly noted by increases in Euglypha species. Transfer function results infer a distinct lowering of water tables in this period. A hydrological response to recent climate change is a tenable hypothesis to explain this change; however other possible explanations include selective test decay, vertical zonation of living amoebae, ombrotrophication and local hydrological change. It is suggested that a peatland response to climatic change is the most probable hypothesis, showing the sensitivity of marginal peatlands to recent climatic change
Test particle comparison of heavy atomic and molecular ion distributions at Mars
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106919/1/jgra50899.pd
Single-epoch VLBI imaging study of bright active galactic nuclei at 2 and 8 GHz
We investigate statistical and individual astrophysical properties of active
galactic nuclei (AGNs), such as parsec-scale flux density, core dominance,
angular and linear sizes, maximum observed brightness temperatures of VLBI core
components, spectral index distributions for core and jet components, and
evolution of brightness temperature along the jets. Furthermore, we
statistically compare core flux densities and brightness temperature as well as
jet spectral indices of gamma-ray bright and weak sources. We used 19 very long
baseline interferometry (VLBI) observing sessions carried out simultaneously at
2.3 and 8.6 GHz with the participation of 10 Very Long Baseline Array (VLBA)
stations and up to 10 additional geodetic telescopes. The observations span the
period 1998-2003. We present here single-epoch results from high-resolution
radio observations of 370 AGNs. Our VLBI images at 2.3 and 8.6 GHz as well as
Gaussian models are presented and analyzed. At least one-fourth of the cores
are completely unresolved on the longest baselines of the global VLBI
observations. The VLBI core components are partially opaque with the median
value of spectral index of alpha_core=0.3, while the jet features are usually
optically thin alpha_jet=-0.7. The spectral index typically decreases along the
jet ridge line owing to the spectral aging, with a median value of -0.05
mas^-1. Brightness temperatures are found to be affected by Doppler boosting
and reaching up to \sim10^13 K with a median of \sim2.5x10^11 K at both
frequencies. The brightness temperature gradients along the jets typically
follow a power law T_b\simr^-2.2 at both frequencies. 147 sources (40%)
positionally associated with gamma-ray detections from the Fermi LAT Second
Source Catalog have higher core flux densities and brightness temperatures, and
are characterized by the less steep radio spectrum of the optically thin jet
emission.Comment: 15 pages, 21 figures, accepted by A&A on May 22, 2012, machine
readable tables are available from the source of the pape
A systematic review of randomised controlled trials on the effectiveness of exercise programs on lumbo pelvic pain among postnatal women
Background: A substantial number of women tend to be affected by Lumbo Pelvic Pain (LPP) following child birth.
Physical exercise is indicated as a beneficial method to relieve LPP, but individual studies appear to suggest mixed
findings about its effectiveness. This systematic review aimed to synthesise evidence from randomised controlled trials on the effectiveness of exercise on LPP among postnatal women to inform policy, practice and future research.
Methods: A systematic review was conducted of all randomised controlled trials published between January 1990 and July 2014, identified through a comprehensive search of following databases: PubMed, PEDro, Embase, Cinahl, Medline, SPORTDiscus, Cochrane Pregnancy and Childbirth Group’s Trials Register, and electronic libraries of authors’institutions.
Randomised controlled trials were eligible for inclusion if the intervention comprised of postnatal exercise for women
with LPP onset during pregnancy or within 3 months after delivery and the outcome measures included changes in
LPP. Selected articles were assessed using the PEDro Scale for methodological quality and findings were synthesised narratively as meta-analysis was found to be inappropriate due to heterogeneity among included studies.
Results: Four randomised controlled trials were included, involving 251 postnatal women. Three trials were rated as
of ‘good’ methodological quality. All trials, except one, were at low risk of bias. The trials included physical exercise
programs with varying components, differing modes of delivery, follow up times and outcome measures. Intervention
in one trial, involving physical therapy with specific stabilising exercises, proved to be effective in reducing LPP
intensity. An improvement in gluteal pain on the right side was reported in another trial and a significant difference in
pain frequency in another.
Conclusion: Our review indicates that only few randomised controlled trials have evaluated the effectiveness of
exercise on LPP among postnatal women. There is also a great amount of variability across existing trials in the
components of exercise programs, modes of delivery, follow up times and outcome measures. While there is some
evidence to indicate the effectiveness of exercise for relieving LPP, further good quality trials are needed to ascertain
the most effective elements of postnatal exercise programs suited for LPP treatment
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