1,112 research outputs found
Searching for molecular outflows in Hyper-Luminous Infrared Galaxies
We present constraints on the molecular outflows in a sample of five
Hyper-Luminous Infrared Galaxies using Herschel observations of the OH doublet
at 119 {\mu}m. We have detected the OH doublet in three cases: one purely in
emission and two purely in absorption. The observed emission profile has a
significant blueshifted wing suggesting the possibility of tracing an outflow.
Out of the two absorption profiles, one seems to be consistent with the
systemic velocity while the other clearly indicates the presence of a molecular
outflow whose maximum velocity is about ~1500 km/s. Our analysis shows that
this system is in general agreement with previous results on Ultra-luminous
Infrared Galaxies and QSOs, whose outflow velocities do not seem to correlate
with stellar masses or starburst luminosities (star formation rates). Instead
the galaxy outflow likely arises from an embedded AGN.Comment: Accepted for publication in MNRAS. 13 pages, 11 figures, 4 table
Nuclear effects in at small in deep inelastic scattering on Li and He
We suggest to use polarized nuclear targets of Li and He to study
nuclear effects in the spin dependent structure functions .
These effects are expected to be enhanced by a factor of two as compared to the
unpolarized targets.
We predict a significant dependence at of due to nuclear shadowing and nuclear
enhancement. The effect of nuclear shadowing at is of an
order of 16% for and 10% for
. By imposing the requirement that
the Bjorken sum rule is satisfied we model the effect of enhancement.
We find the effect of enhancement at to be of an
order of for and
for , if enhancement
occupies the region (). We predict
a 2% effect in the difference of the scattering cross sections of deep
inelastic scattering of an unpolarized projectile off Li with =3/2
and =1/2. We also show explicitly that the many-nucleon description of
deep inelastic scattering off Li becomes invalid in the enhancement region
.Comment: 29 pages, 5 figures, RevTe
Multiscale simulation approach to predict the penetration depth of oil between chip and tool during orthogonal cutting of AISI 4140
Cooling lubricants in machining perform important tasks, from cooling and lubrication of the friction partners in contact to the removal of the separated chips. An essential, determining and largely unresolved question in relation to cooling lubricants in ma-chining is to what extent the coolant can get into the cutting zone. The aim of this paper is to address this question by using a multiscale approach to determine the penetration of the cooling lubricant gap. This is achieved by multiscale simulations by means of coupling the results of flow, structural and continuum mechanical simulations. Comparatively, the results of the simulated machining operation are compared with experimental orthogonal cutting tests of AISI 4140
Spectroscopy of superluminous supernova host galaxies. A preference of hydrogen-poor events for extreme emission line galaxies
Superluminous supernovae (SLSNe) are very bright explosions that were only
discovered recently and that show a preference for occurring in faint dwarf
galaxies. Understanding why stellar evolution yields different types of stellar
explosions in these environments is fundamental in order to both uncover the
elusive progenitors of SLSNe and to study star formation in dwarf galaxies. In
this paper, we present the first results of our project to study SUperluminous
Supernova Host galaxIES, focusing on the sample for which we have obtained
spectroscopy. We show that SLSNe-I and SLSNe-R (hydrogen-poor) often (~50% in
our sample) occur in a class of galaxies that is known as Extreme Emission Line
Galaxies (EELGs). The probability of this happening by chance is negligible and
we therefore conclude that the extreme environmental conditions and the SLSN
phenomenon are related. In contrast, SLSNe-II (hydrogen-rich) occur in more
massive, more metal-rich galaxies with softer radiation fields. Therefore, if
SLSNe-II constitute a uniform class, their progenitor systems are likely
different from those of H-poor SLSNe. Gamma-ray bursts (GRBs) are, on average,
not found in as extreme environments as H-poor SLSNe. We propose that H-poor
SLSNe result from the very first stars exploding in a starburst, even earlier
than GRBs. This might indicate a bottom-light initial mass function in these
systems. SLSNe present a novel method of selecting candidate EELGs independent
of their luminosity.Comment: Published version, matches proofs. Accepted 2015 February 13. 23
pages, 8 figures, 4 tables. Minor changes with respect to previous versio
A three dimensional finite element model for arterial clamping
Motivation and Introduction Arterial clamps are chosen to compress arteries during surgery so that blood flow is arrested. Arterial compression, however, may lead to injuries of the vessel wall, which are associated with a variety of severe short-term and long-term complications. For example, clamp induced injuries may cause spontaneous occlusion of the vessel after the operation, which leads to infarction of the downstream tissues. Therefore, surgeons require arterial clamps that allow efficient compression and cause only minimal injury. Severity and distribution of injuries depend on Í‘iÍ’ the arterial type Í“1,2Í”, the geometry and the nonlinear and anisotropic material behavior of the clamped multi-layered artery, Í‘iiÍ’ the design of the chosen clamp Í“3-7Í” and Í‘iiiÍ’ the applied clamping forces Í“2,6,8,9Í”. The optimization of this mechanical problem requires a numerical model, which considers appropriately all decisive factors. Yet, such a model is not available in the literature to date. Appropriate numerical models may lead to substantial improvements of arterial clamp designs, and thus are of potential interest for surgeons and clamp suppliers. In the past the demand for appropriate arterial clamps has led to a great variety of different designs and techniques. A suitable clamp design provides easy handling, good vessel grip and efficient vessel occlusion, and it is aimed to minimize arterial injuries. Clamps are named after their inventors as, for example, Blalock, Cooley, DeBakey, Fogarty, Potts, Satinsky, etc. They are available in different sizes with straight, curved or angled branches. Their jaws may be plain or have spikes, and they may be silicone filled. The existing designs are based on surgical intuition rather than on mechanical considerations. Consequently, the effects of clamping and the suitability of clamp designs have been investigated by means of experimental studies rather than by mechanical analyses. To the authors' knowledge, only Í“10Í” presented a mathematical approach with the goal to determine the minimum vascular occlusive force. However, this simplifying analytical model does not consider the crucial constitutive behavior of arterial walls. Thus, it is incapable of calculating wall stresses. Despite the clinical significance of arterial clamping there are relatively few studies, which are concerned with its local effects. Most of the experimental investigations are animal studies and focus on morphological changes. The observed injuries range from mild damage, which involves only the intima, to severe damage with total disruptions of the media, layer delaminations and even total wall disruptions with associated bleeding. In addition, long-term changes such as stenoses Í“11Í” and intimal hyperplasia-excessive thickening of the intima due to tissue growth Í“1Í”-have been observed. Beside structural changes also functional changes of clamped arteries have been investigated, for example, the ability to relax or contract upon application of certain drugs Í“7,8Í” and the ability to inhibit blood clotting Í“12,13Í”. The influences of the clamping force Í“2,6,8,9Í” and of the duration of clamping Í“14Í” have been studied. Moreover, comparisons of different types of arteries Í“2Í” and different clamp designs Í“3-7Í” in regard to clamp induced wall injury have been performed. These studies have identified the types and the consequences of clamp induced injuries and thus have demonstrated the importance of proper clamp designs. However, experimental studies are afflicted with a number of disadvantages. They are expensive and time-consuming and it is disputable if results of animal arteries are representative for human arteries. The significance of experimental studies is definitely restricted to the chosen arteries, instruments and clamping conditions. A fundamental shortcoming is that the results of existing experimental studies do not provide insights into the mechanical process of arterial clamping. The latter is determined by the three-dimensional stress-strain distributions in the clamped arterial wall. To overcome these shortcomings we developed a threedimensional finite element model for arterial clamping. The essential approach is to model the artery as a two-layer fiber-reinforced material with the fibers corresponding to the collagenous component of the material. The two layers represent the media Í‘the middle layer of the arteryÍ’ and the adventitia Í‘the outer layerÍ’. Th
Unraveling the genetic cause of hereditary ophthalmic disorders in Arab societies from Israel and the Palestinian Authority
Visual impairment due to inherited ophthalmic disorders is amongst the most common disabilities observed in populations
practicing consanguineous marriages. Here we investigated the molecular genetic basis of an unselected broad range of
ophthalmic disorders in 20 consanguineous families from Arab villages of Israel and the Palestinian Authority. Most patients
had little or very poor prior clinical workup and were recruited in a field study. Homozygosity mapping followed by
candidate gene sequencing applying conventional Sanger sequencing or targeted next generation sequencing was performed
in six families. In the remaining 14 families, one affected subject per family was chosen for whole exome sequencing. We
discovered likely disease-causing variants, all homozygous, in 19 of 20 independent families (95%) including a previously
reported novel disease gene for congenital nystagmus associated with foveal hypoplasia. Moreover, we found a family in
which disease-causing variants for two collagenopathies — Stickler and Knobloch syndrome — segregate within a large
sibship. Nine of the 19 distinct variants observed in this study were novel. Our study demonstrated a very high molecular
diagnostic yield for a highly diverse spectrum of rare ophthalmic disorders in Arab patients from Israel and the Palestinian
Authority, even with very limited prior clinical investigation. We conclude that ‘genetic testing first' may be an economic
way to direct clinical care and to support proper genetic counseling and risk assessment in these families
SNe 2013K and 2013am: observed and physical properties of two slow, normal Type IIP events
We present one year of optical and near-infrared photometry and spectroscopy
of the Type IIP SNe 2013K and 2013am. Both objects are affected by significant
extinction, due to their location in dusty regions of their respective host
galaxies, ESO 009-10 and NGC 3623 (M65). From the photospheric to nebular
phases, these objects display spectra congruent with those of underluminous
Type IIP SNe (i.e. the archetypal SNe 1997D or 2005cs), showing low
photospheric velocities (~2 X 10**3 km/s at 50d) together with features arising
from Ba II which are particularly prominent in faint SNe IIP. The peak V-band
magnitudes of SN 2013K (-15.6 mag) and SN 2013am (-16.2 mag) are fainter than
standard-luminosity Type IIP SNe. The ejected Nickel masses are 0.012+-0.010
and 0.015+-0.006 Msol for SN 2013K and SN 2013am, respectively. The physical
properties of the progenitors at the time of explosion are derived through
hydrodynamical modelling. Fitting the bolometric curves, the expansion velocity
and the temperature evolution, we infer total ejected masses of 12 and 11.5
Msol, pre-SN radii of ~460 and ~360 Rsol, and explosion energies of 0.34 foe
and 0.40 foe for SN 2013K and SN 2013am. Late time spectra are used to estimate
the progenitor masses from the strength of nebular emission lines, which turn
out to be consistent with red supergiant progenitors of ~15 Msol. For both SNe,
a low-energy explosion of a moderate-mass red supergiant star is therefore the
favoured scenario.Comment: accepted for publication MNRA
Arginase Inhibition Reverses Monocrotaline-Induced Pulmonary Hypertension
Pulmonary hypertension (PH) is a heterogeneous disorder associated with a poor
prognosis. Thus, the development of novel treatment strategies is of great
interest. The enzyme arginase (Arg) is emerging as important player in PH
development. The aim of the current study was to determine the expression of
ArgI and ArgII as well as the effects of Arg inhibition in a rat model of PH.
PH was induced in 35 Sprague–Dawley rats by monocrotaline (MCT, 60 mg/kg as
single-dose). There were three experimental groups: sham-treated controls
(control group, n = 11), MCT-induced PH (MCT group, n = 11) and MCT-induced PH
treated with the Arg inhibitor Nω-hydroxy-nor-l-arginine (nor-NOHA;
MCT/NorNoha group, n = 13). ArgI and ArgII expression was determined by
immunohistochemistry and Western blot. Right ventricular systolic pressure
(RVPsys) was measured and lung tissue remodeling was determined. Induction of
PH resulted in an increase in RVPsys (81 ± 16 mmHg) compared to the control
group (41 ± 15 mmHg, p = 0.002) accompanied by a significant elevation of
histological sum-score (8.2 ± 2.4 in the MCT compared to 1.6 ± 1.6 in the
control group, p < 0.001). Both, ArgI and ArgII were relevantly expressed in
lung tissue and there was a significant increase in the MCT compared to the
control group (p < 0.01). Arg inhibition resulted in a significant reduction
of RVPsys to 52 ± 19 mmHg (p = 0.006) and histological sum-score to 5.8 ± 1.4
compared to the MCT group (p = 0.022). PH leads to increased expression of
Arg. Arg inhibition leads to reduction of RVPsys and diminished lung tissue
remodeling and therefore represents a potential treatment strategy in PH
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