2,095 research outputs found
Breaking the Curve with CANDELS: A Bayesian Approach to Reveal the Non-Universality of the Dust-Attenuation Law at High Redshift
Dust attenuation affects nearly all observational aspects of galaxy
evolution, yet very little is known about the form of the dust-attenuation law
in the distant Universe. Here, we model the spectral energy distributions
(SEDs) of galaxies at z = 1.5--3 from CANDELS with rest-frame UV to near-IR
imaging under different assumptions about the dust law, and compare the amount
of inferred attenuated light with the observed infrared (IR) luminosities. Some
individual galaxies show strong Bayesian evidence in preference of one dust law
over another, and this preference agrees with their observed location on the
plane of infrared excess (IRX, ) and UV slope
(). We generalize the shape of the dust law with an empirical model,
where
is the dust law of Calzetti et al. (2000), and show that there
exists a correlation between the color excess and tilt with
+ . Galaxies with high
color excess have a shallower, starburst-like law, and those with low color
excess have a steeper, SMC-like law. Surprisingly, the galaxies in our sample
show no correlation between the shape of the dust law and stellar mass,
star-formation rate, or . The change in the dust law with color excess
is consistent with a model where attenuation is caused by by scattering, a
mixed star-dust geometry, and/or trends with stellar population age,
metallicity, and dust grain size. This rest-frame UV-to-near-IR method shows
potential to constrain the dust law at even higher () redshifts.Comment: 20 pages, 18 figures, resubmitted to Ap
Psychological, cognitive factors and contextual influences in pain and pain-related suffering as revealed by a combined qualitative and quantitative assessment approach
Previous psychophysiological research suggests that pain measurement needs to go
beyond the assessment of Pain Intensity and Unpleasantness by adding the evaluation of
Pain-Related Suffering. Based on this three-dimensional approach, we attempted to elucidate
who is more likely to suffer by identifying reasons that may lead individuals to report
Pain and Pain-Related Suffering more than others. A sample of 24 healthy participants
(age range 18±33) underwent four different sessions involving the evaluation of experimentally
induced phasic and tonic pain. We applied two decision tree models to identify
variables (selected from psychological questionnaires regarding pain and descriptors
from post-session interviews) that provided a qualitative characterization of the degrees
of Pain Intensity, Unpleasantness and Suffering and assessed the respective impact of
contextual influences. The overall classification accuracy of the decision trees was 75%
for Intensity, 77% for Unpleasantness and 78% for Pain-Related Suffering. The reporting
of suffering was predominantly associated with fear of pain and active cognitive coping
strategies, pain intensity with bodily competence conveying strength and resistance and
unpleasantness with the degree of fear of pain and catastrophizing. These results indicate
that the appraisal of the three pain dimensions was largely determined by stable psychological
constructs. They also suggest that individuals manifesting higher active coping
strategies may suffer less despite enhanced pain and those who fear pain may suffer
even under low pain. The second decision tree model revealed that suffering did not
depend on pain alone, but that the complex rating-related decision making can be shifted
by situational factors (context, emotional and cognitive). The impact of coping and fear of pain on individual Pain-Related Suffering may highlight the importance of improving cognitive
coping strategies in clinical settings
A novel PKC activating molecule promotes neuroblast differentiation and delivery of newborn neurons in brain injuries
Neural stem cells are activated within neurogenic niches in response to brain injuries. This results in the production of neuroblasts, which unsuccessfully attempt to migrate toward the damaged tissue. Injuries constitute a gliogenic/non-neurogenic niche generated by the presence of anti-neurogenic signals, which impair neuronal differentiation and migration. Kinases of the protein kinase C (PKC) family mediate the release of growth factors that participate in different steps of the neurogenic process, particularly, novel PKC isozymes facilitate the release of the neurogenic growth factor neuregulin. We have demonstrated herein that a plant derived diterpene, (EOF2; CAS number 2230806-06-9), with the capacity to activate PKC facilitates the release of neuregulin 1, and promotes neuroblasts differentiation and survival in cultures of subventricular zone (SVZ) isolated cells in a novel PKC dependent manner. Local infusion of this compound in mechanical cortical injuries induces neuroblast enrichment within the perilesional area, and noninvasive intranasal administration of EOF2 promotes migration of neuroblasts from the SVZ towards the injury, allowing their survival and differentiation into mature neurons, being some of them cholinergic and GABAergic. Our results elucidate the mechanism of EOF2 promoting neurogenesis in injuries and highlight the role of novel PKC isozymes as targets in brain injury regeneration
Rectal Transmission of Transmitted/Founder HIV-1 Is Efficiently Prevented by Topical 1% Tenofovir in BLT Humanized Mice
Rectal microbicides are being developed to prevent new HIV infections in both men and women. We focused our in vivo preclinical efficacy study on rectally-applied tenofovir. BLT humanized mice (nâ=â43) were rectally inoculated with either the primary isolate HIV-1(JRCSF) or the MSM-derived transmitted/founder (T/F) virus HIV-1(THRO) within 30 minutes following treatment with topical 1% tenofovir or vehicle. Under our experimental conditions, in the absence of drug treatment we observed 50% and 60% rectal transmission by HIV-1(JRCSF) and HIV-1(THRO), respectively. Topical tenofovir reduced rectal transmission to 8% (1/12; log rank pâ=â0.03) for HIV-1(JRCSF) and 0% (0/6; log rank pâ=â0.02) for HIV-1(THRO). This is the first demonstration that any human T/F HIV-1 rectally infects humanized mice and that transmission of the T/F virus can be efficiently blocked by rectally applied 1% tenofovir. These results obtained in BLT mice, along with recent ex vivo, Phase 1 trial and non-human primate reports, provide a critically important step forward in the development of tenofovir-based rectal microbicides
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Neutrinos below 100 TeV from the southern sky employing refined veto techniques to IceCube data
Many Galactic sources of gamma rays, such as supernova remnants, are expected to produce neutrinos with a typical energy cutoff well below 100 TeV. For the IceCube Neutrino Observatory located at the South Pole, the southern sky, containing the inner part of the Galactic plane and the Galactic Center, is a particularly challenging region at these energies, because of the large background of atmospheric muons. In this paper, we present recent advancements in data selection strategies for track-like muon neutrino events with energies below 100 TeV from the southern sky. The strategies utilize the outer detector regions as veto and features of the signal pattern to reduce the background of atmospheric muons to a level which, for the first time, allows IceCube searching for point-like sources of neutrinos in the southern sky at energies between 100 GeV and several TeV in the muon neutrino charged current channel. No significant clustering of neutrinos above background expectation was observed in four years of data recorded with the completed IceCube detector. Upper limits on the neutrino flux for a number of spectral hypotheses are reported for a list of astrophysical objects in the southern hemisphere
Physical properties of Herschel selected galaxies in a semi-analytic galaxy formation model
[Abridged] We make use of a semi-analytic cosmological model that includes
simple prescriptions for dust attenuation and emission to make predictions for
the observable and physical properties of galaxies that may be detected by the
recently launched Herschel Space Observatory in deep fields such as
GOODS-Herschel. We compare our predictions for differential galaxy number
counts in the PACS (100 & 160) and SPIRE (250, 350, and 500 micron) bands with
available observations. We find very good agreement with the counts in the PACS
bands, for the overall counts and for galaxies binned by redshift at z< 2. At z
> 2 our model underpredicts the number of bright galaxies by a factor of ten.
The agreement is much worse for all three SPIRE bands, and becomes
progressively worse with increasing wavelength. We discuss a number of possible
reasons for these discrepancies, and hypothesize that the effect of blending on
the observational flux estimates is likely to be the dominant issue. We note
that the PACS number counts are relatively robust to changes in the dust
emission templates, while the predicted SPIRE number counts are more template
dependent. We present quantitative predictions for the relationship between the
observed PACS 160 and SPIRE 250 micron fluxes and physical quantities such as
halo mass, stellar mass, cold gas mass, star formation rate, and total infrared
(IR) luminosity, at different redshifts. We also present quantitative
predictions for the correlation between PACS 160 micron flux and the
probability that a galaxy has experienced a recent major or minor merger.
Although our models predict a strong correlation between these quantities, such
that more IR-luminous galaxies are more likely to be merger-driven, we find
that more than half of all high redshift IR-luminous galaxies detected by
Herschel are able to attain their high star formation rates without enhancement
by a merger.Comment: Accepted for publication in MNRA
Measurement of the α ratio and (n, γ) cross section of 235U from 0.2 to 200 eV at n_TOF
We measured the neutron capture-to-fission cross-section ratio (α ratio) and the capture cross section of 235U between 0.2 and 200 eV at the n_TOF facility at CERN. The simultaneous measurement of neutron-induced capture and fission rates was performed by means of the n_TOF BaF2 Total Absorption Calorimeter (TAC), used for detection of γ rays, in combination with a set of micromegas detectors used as fission tagging detectors. The energy dependence of the capture cross section was obtained with help of the 6 Li(n,t) standard reaction determining the n_TOF neutron fluence; the well-known integral of the 235U(n, f ) cross section between 7.8 and 11 eV was then used for its absolute normalization. The α ratio, obtained with slightly higher statistical fluctuations, was determined directly, without need for any reference cross section. To perform the analysis of this measurement we developed a new methodology to correct the experimentally observed effect that the probabilities of detecting a fission reaction in the TAC and the micromegas detectors are not independent. The results of this work have been used in a new evaluation of 235U performed within the scope of the Collaborative International Evaluated Library Organisation (CIELO) Project, and are consistent with the ENDF/B-VIII.0 and JEFF-3.3 capture cross sections below 4 eV and above 100 eV. However, the measured capture cross section is on average 10% larger between 4 and 100 eV.This work was supported in part by the Spanish national company for radioactive waste management, ENRESA,
through the CIEMAT-ENRESA agreements on âTransmutaciĂłn de radionucleidos de vida larga como soporte a la gestiĂłn de residuos radioactivos de alta actividadâ; by the
Spanish Ministerio de EconomĂa, Industria y Competitividad,
through the projects FPA2014-53290-C2-1, FPA2016-76765-
P, and FPA2017-82647-P; and by the European Commission
7th Framework Programme project CHANDA (Grant No.
FP7-605203)
All-sky search for time-integrated neutrino emission from astrophysical sources with 7 years of IceCube data
Since the recent detection of an astrophysical flux of high energy neutrinos,
the question of its origin has not yet fully been answered. Much of what is
known about this flux comes from a small event sample of high neutrino purity,
good energy resolution, but large angular uncertainties. In searches for
point-like sources, on the other hand, the best performance is given by using
large statistics and good angular reconstructions. Track-like muon events
produced in neutrino interactions satisfy these requirements. We present here
the results of searches for point-like sources with neutrinos using data
acquired by the IceCube detector over seven years from 2008--2015. The
discovery potential of the analysis in the northern sky is now significantly
below , on average
lower than the sensitivity of the previously published analysis of four
years exposure. No significant clustering of neutrinos above background
expectation was observed, and implications for prominent neutrino source
candidates are discussed.Comment: 19 pages, 17 figures, 3 tables; ; submitted to The Astrophysical
Journa
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