413 research outputs found
Recommended from our members
A z = 3.045 Lyα emitting halo hosting a QSO and a possible candidate for AGN-triggered star formation
In this third paper in a series on the nature of extended, asymmetric Lyman
alpha emitters at z ~ 3 we report the discovery, in an ultra-deep, blind,
spectroscopic long-slit survey, of a Lyman alpha emitting halo around a QSO at
redshift 3.045. The QSO is a previously known, obscured AGN. The halo appears
extended along the direction of the slit and exhibits two faint patches
separated by 17 proper kpc in projection from the QSO. Comparison of the
2-dimensional spectrum with archival HST ACS images shows that these patches
coincide spatially with emission from a peculiar, dumbbell-shaped, faint
galaxy. The assumptions that the Lyman alpha emission patches are originating
in the galaxy and that the galaxy is physically related to the QSO are at
variance with photometric estimates of the galaxy redshift. We show, however,
that a population of very young stars at the redshift of the QSO may fit the
existing rest frame broad band UV photometry of the galaxy. If this scenario is
correct then the symmetry of the galaxy in continuum and Lyman alpha emission,
the extension of the QSO's Lyman alpha emission in its direction, and the
likely presence of a young stellar population in close proximity to a
(short-lived) AGN suggest that this may be an example of AGN feedback
triggering external star formation in high redshift galaxies
Probing the thermal state of the intergalactic medium at z > 5 with the transmission spikes in high-resolution Ly α forest spectra
We compare a sample of five high-resolution, high S/N Ly forest
spectra of bright QSOs aimed at spectrally resolving the
last remaining transmission spikes at with those obtained from mock
absorption spectra from the Sherwood and Sherwood-Relics suites of
hydrodynamical simulations of the intergalactic medium (IGM). We use a profile
fitting procedure for the inverted transmitted flux, , similar to the
widely used Voigt profile fitting of the transmitted flux at lower
redshifts, to characterise the transmission spikes that probe predominately
underdense regions of the IGM. We are able to reproduce the width and height
distributions of the transmission spikes, both with optically thin simulations
of the post-reionization Universe using a homogeneous UV background and full
radiative transfer simulations of a late reionization model. We find that the
width of the fitted components of the simulated transmission spikes is very
sensitive to the instantaneous temperature of the reionized IGM. The internal
structures of the spikes are more prominant in low temeperature models of the
IGM. The width distribution of the observed transmission spikes, which require
high spectral resolution ( 8 km/s) to be resolved, is reproduced for
optically thin simulations with a temperature at mean density of K at . This is weakly
dependent on the slope of the temperature-density relation, which is favoured
to be moderately steeper than isothermal. In the inhomogeneous, late
reionization, full radiative transfer simulations where islands of neutral
hydrogen persist to , the width distribution of the observed
transmission spikes is consistent with the range of caused by spatial
fluctuations in the temperature-density relation
The effect on the extracellular matrix of the deep fascia in response to leg lengthening
<p>Abstract</p> <p>Background</p> <p>Whereas the alterations of diverse tissues in cellular and molecular levels have been investigated during leg lengthening via microscopy and biochemical studies, little is known about the response of deep fascia. This study aims to investigate the changes of the extracellular matrix in deep fascia in response to leg lengthening.</p> <p>Methods</p> <p>Animal model of leg lengthening was established in New Zealand white rabbits. Distraction was initiated at a rate of 1 mm/day and 2 mm/day in two steps, and preceded until increases of 10% and 20% in the initial length of tibia had been achieved. Alcian blue stain and picrosirius-polarization method were used for the study of the extracellular matrix of deep fascia samples. Leica DM LA image analysis system was used to investigate the quantitative changes of collagen type I and III.</p> <p>Results</p> <p>Alcian blue stain showed that glycosaminoglycans of fascia of each group were composed of chondroitin sulphate and heparin sulphate, but not of keratan sulphate. Under the polarization microscopy, the fascia consisted mainly of collagen type I. After leg lengthening, the percentage of collagen type III increased. The most similar collagen composition of the fascia to that of the normal fascia was detected at a 20% increase in tibia length achieved via a distraction rate of 1 mm/d.</p> <p>Conclusion</p> <p>The changes in collagen distribution and composition occur in deep fascia during leg lengthening. Although different lengthening schemes resulted in varied matrix changes, the most comparable collagen composition to be demonstrated under the scheme of a distraction rate of 1 mm/day and 20% increase in tibia length. Efficient fascia regeneration is initiated only in certain combinations of the leg load parameters including appropriate intensity and duration time, e.g., either low density distraction that persist a relatively short time or high distraction rates.</p
Rib Cage Deformities Alter Respiratory Muscle Action and Chest Wall Function in Patients with Severe Osteogenesis Imperfecta
Osteogenesis imperfecta (OI) is an inherited connective tissue disorder characterized by bone fragility, multiple fractures and significant chest wall deformities. Cardiopulmonary insufficiency is the leading cause of death in these patients.Seven patients with severe OI type III, 15 with moderate OI type IV and 26 healthy subjects were studied. In addition to standard spirometry, rib cage geometry, breathing pattern and regional chest wall volume changes at rest in seated and supine position were assessed by opto-electronic plethysmography to investigate if structural modifications of the rib cage in OI have consequences on ventilatory pattern. One-way or two-way analysis of variance was performed to compare the results between the three groups and the two postures. compared to predicted values, on condition that updated reference equations are considered. In both positions, ventilation was lower in OI patients than control because of lower tidal volume (p<0.01). In contrast to OI type IV patients, whose chest wall geometry and function was normal, OI type III patients were characterized by reduced (p<0.01) angle at the sternum (pectus carinatum), paradoxical inspiratory inward motion of the pulmonary rib cage, significant thoraco-abdominal asynchronies and rib cage distortions in supine position (p<0.001).In conclusion, the restrictive respiratory pattern of Osteogenesis Imperfecta is closely related to the severity of the disease and to the sternal deformities. Pectus carinatum characterizes OI type III patients and alters respiratory muscles coordination, leading to chest wall and rib cage distortions and an inefficient ventilator pattern. OI type IV is characterized by lower alterations in the respiratory function. These findings suggest that functional assessment and treatment of OI should be differentiated in these two forms of the disease
Pathogenic Mouse Hepatitis Virus or Poly(I:C) Induce IL-33 in Hepatocytes in Murine Models of Hepatitis.
International audienceThe IL-33/ST2 axis is known to be involved in liver pathologies. Although, the IL-33 levels increased in sera of viral hepatitis patients in human, the cellular sources of IL-33 in viral hepatitis remained obscure. Therefore, we aimed to investigate the expression of IL-33 in murine fulminant hepatitis induced by a Toll like receptor (TLR3) viral mimetic, poly(I:C) or by pathogenic mouse hepatitis virus (L2-MHV3). The administration of poly(I:C) plus D-galactosamine (D-GalN) in mice led to acute liver injury associated with the induction of IL-33 expression in liver sinusoidal endothelial cells (LSEC) and vascular endothelial cells (VEC), while the administration of poly(I:C) alone led to hepatocyte specific IL-33 expression in addition to vascular IL-33 expression. The hepatocyte-specific IL-33 expression was down-regulated in NK-depleted poly(I:C) treated mice suggesting a partial regulation of IL-33 by NK cells. The CD1d KO (NKT deficient) mice showed hepatoprotection against poly(I:C)-induced hepatitis in association with increased number of IL-33 expressing hepatocytes in CD1d KO mice than WT controls. These results suggest that hepatocyte-specific IL-33 expression in poly(I:C) induced liver injury was partially dependent of NK cells and with limited role of NKT cells. In parallel, the L2-MHV3 infection in mice induced fulminant hepatitis associated with up-regulated IL-33 expression as well as pro-inflammatory cytokine microenvironment in liver. The LSEC and VEC expressed inducible expression of IL-33 following L2-MHV3 infection but the hepatocyte-specific IL-33 expression was only evident between 24 to 32h of post infection. In conclusion, the alarmin cytokine IL-33 was over-expressed during fulminant hepatitis in mice with LSEC, VEC and hepatocytes as potential sources of IL-33
General Relativistic Gravity Gradiometry
Gravity gradiometry within the framework of the general theory of relativity
involves the measurement of the elements of the relativistic tidal matrix,
which is theoretically obtained via the projection of the spacetime curvature
tensor upon the nonrotating orthonormal tetrad frame of a geodesic observer.
The behavior of the measured components of the curvature tensor under Lorentz
boosts is briefly described in connection with the existence of certain special
tidal directions. Relativistic gravity gradiometry in the exterior
gravitational field of a rotating mass is discussed and a gravitomagnetic beat
effect along an inclined spherical geodesic orbit is elucidated.Comment: 18 pages, invited contribution to appear in "Relativistic Geodesy:
Foundations and Applications", D. Puetzfeld et al. (eds.), 2018; v2: matches
version published in: D. Puetzfeld and C. L\"ammerzahl (eds.) "Relativistic
Geodesy" (Springer, Cham, 2019), pp. 143-15
Use of cancer-specific yeast-secreted in vivo biotinylated recombinant antibodies for serum biomarker discovery
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Performance-based vs socially supportive culture:a cross-national study of descriptive norms and entrepreneurship
This paper is a cross-national study testing a framework relating cultural descriptive norms to entrepreneurship in a sample of 40 nations. Based on data from the Global Leadership and Organizational Behavior Effectiveness project, we identify two higher-order dimensions of culture â socially supportive culture (SSC) and performance-based culture (PBC) â and relate them to entrepreneurship rates and associated supply-side and demand-side variables available from the Global Entrepreneurship Monitor. Findings provide strong support for a social capital/SSC and supply-side variable explanation of entrepreneurship rate. PBC predicts demand-side variables, such as opportunity existence and the quality of formal institutions to support entrepreneurship
Updating Fearful Memories with Extinction Training during Reconsolidation: A Human Study Using Auditory Aversive Stimuli
Learning to fear danger in the environment is essential to survival, but dysregulation of the fear system is at the core of many anxiety disorders. As a consequence, a great interest has emerged in developing strategies for suppressing fear memories in maladaptive cases. Recent research has focused in the process of reconsolidation where memories become labile after being retrieved. In a behavioral manipulation, Schiller et al., (2010) reported that extinction training, administrated during memory reconsolidation, could erase fear responses. The implications of this study are crucial for the possible treatment of anxiety disorders without the administration of drugs. However, attempts to replicate this effect by other groups have been so far unsuccessful. We sought out to reproduce Schiller et al., (2010) findings in a different fear conditioning paradigm based on auditory aversive stimuli instead of electric shock. Following a within-subject design, participants were conditioned to two different sounds and skin conductance response (SCR) was recorded as a measure of fear. Our results demonstrated that only the conditioned stimulus that was reminded 10 minutes before extinction training did not reinstate a fear response after a reminder trial consisting of the presentation of the unconditioned stimuli. For the first time, we replicated Schiller et al., (2010) behavioral manipulation and extended it to an auditory fear conditioning paradigm
- âŠ