1,695 research outputs found
Reactions forming C(0,+)n=2,10, Cn=2,4H(0,+) and C3H(0,+) in the gas phase: semi empirical branching ratios
The aim of this paper is to provide a new set of branching ratios for
interstellar and planetary chemical networks based on a semi empirical model.
We applied, instead of zero order theory (i.e. only the most exoergic decaying
channel is considered), a statistical microcanonical model based on the
construction of breakdown curves and using experimental high velocity collision
branching ratios for their parametriza- tion. We applied the model to
ion-molecule, neutral-neutral, and ion-pair reactions implemented in the few
popular databases for astrochemistry such as KIDA, OSU and UMIST. We studied
the reactions of carbon and hydrocarbon species with electrons, He+, H+, CH+,
CH, C, and C+ leading to intermediate complexes of the type Cn=2,10, Cn=2,4 H,
C3 H2, C+n=2,10, Cn=2,4 H+, or C3 H+2 . Comparison of predictions with
measurements supports the validity of the model. Huge deviations with respect
to database values are often obtained. Effects of the new branching ratios in
time dependant chemistry for dark clouds and for photodissociation region
chemistry with conditions similar to those found in the Horsehead Nebula are
discussed
The CountEm software: simple, efficient and unbiased population size estimation
Population size estimation is essential in ecology and conservation studies. Aerial photography can facilitate this laborious task with high resolution images. However, in images with thousands of individuals exhaustive manual counting is tedious, slow and difficult to verify. Computer vision software may work under some particular conditions but they are generally biased and known to fail in several situations. The CountEm software is a simple alternative based on geometric sampling. It provides a fast and unbiased size estimation for all sorts of populations. The only requirement is that the discrete objects (e.g. animals) in the target population are unambiguously distinguishable for counting in a still image. Typical relative standard errors in the 5?10% range are obtained after counting ~200 properly sampled animals in about 5?min irrespective of population size. The CountEm ver. 1.4.1 is presented here, which includes a guided mode with a simple software interface.MC acknowledges financial support from the
AYA-2015-66357-R (MINECO/FEDER) project
Occupational Asthma to Detergent Protease Associated With a Late-Phase Neutrophilic Cutaneous Response
International audienceBackground: The relationships between asbestos exposure and colorectal cancer remain controversial. Objectives: We examined the association between asbestos exposure and colorectal cancer incidence. Methods: Volunteer retired workers previously exposed to asbestos were invited to participate in the French ARDCo screening program between 2003 and 2005. Additional data on risk factors for colorectal cancer were collected from the ARDCo-Nut subsample of 3,769 participants in 2011. Cases of colon and rectal cancer were ascertained each year through 2014 based on eligibility for free medical care following a cancer diagnosis. Survival regression based on the Cox model was used to estimate the relative risk of colon and rectal cancer separately, in relation to the time since first exposure (TSFE) and cumulative exposure index (CEI) to asbestos, and with adjustment for smoking in the overall cohort and for smoking, and certain risk factors for these cancers in the ARDCo-Nut subsample. Results: Mean follow-up was 10.2 years among 14,515 men, including 181 colon cancer and 62 rectal cancer cases (41 and 17, respectively, in the ARDCo-Nut subsample). In the overall cohort, after adjusting for smoking, colon cancer was significantly associated with cumulative exposure (HR = 1.14; 95% CI: 1.04, 1.26 for a 1-unit increase in ln-CEI) and â„ 20â40 years since first exposure (HR = 4.67; 95% CI: 1.92, 11.46 vs. 0â20 years TSFE), and inversely associated with 60 years TSFE (HR = 0.26; 95% CI: 0.10, 0.70). Although rectal cancer was also associated with TSFE 20â40 years (HR = 4.57; 95% CI: 1.14, 18.27), it was not associated with ln-CEI, but these findings must be interpreted cautiously due to the small number of cases. Conclusions: Our findings provide support for an association between occupational exposure to asbestos and colon cancer incidence in men. Citation: Paris C, Thaon I, HĂ©rin F, Clin B, Lacourt A, Luc A, Coureau G, Brochard P, Chammingâs S, Gislard A, Galan P, Hercberg S, Wild P, Pairon JC, Andujar P. 2017. Occupational asbestos exposure and incidence of colon and rectal cancers in French men: the Asbestos-Related Diseases Cohort (ARDCo-Nut). Environ Health Perspect 125:409â415;âhttp://dx.doi.org/10.1289/EHP15
Unraveling the Nature of Charge Excitations in LaCuO with Momentum-Resolved Cu -edge Resonant Inelastic X-ray Scattering
Results of model calculations using exact diagonalization reveal the orbital
character of states associated with different Raman loss peaks in Cu -edge
resonant inelastic X-ray scattering (RIXS) from LaCuO. The model
includes electronic orbitals necessary to highlight non-local Zhang-Rice
singlet, charge transfer and - excitations, as well as states with apical
oxygen 2 character. The dispersion of these excitations is discussed with
prospects for resonant final state wave-function mapping. A good agreement with
experiments emphasizes the substantial multi-orbital character of RIXS profiles
in the energy transfer range 1-6 eV.Comment: Original: 4.5 pages. Replaced: 4 pages and 4 figures with updated
content and reference
Fragmentation of small carbon clusters, a review
An overview of the works devoted to fragmentation of small carbon clusters is given in a first part. Fragmentation of swift neutral and (multi) charged carbon clusters studied with the AGAT spectrometer is presented and discussed in a second part
Nuclear break-up of 11Be
The break-up of 11Be was studied at 41AMeV using a secondary beam of 11Be
from the GANIL facility on a 48Ti target by measuring correlations between the
10Be core, the emitted neutrons and gamma rays. The nuclear break-up leading to
the emission of a neutron at large angle in the laboratory frame is identified
with the towing mode through its characteristic n-fragment correlation. The
experimental spectra are compared with a model where the time dependent
Schrodinger equation (TDSE) is solved for the neutron initially in the 11 Be. A
good agreement is found between experiment and theory for the shapes of neutron
experimental energies and angular distributions. The spectroscopic factor of
the 2s orbital is tentatively extracted to be 0.46+-0.15. The neutron emission
from the 1p and 1d orbitals is also studied
Cortical and thalamic connectivity of the auditory anterior ectosylvian cortex of early-deaf cats: Implications for neural mechanisms of crossmodal plasticity
Early hearing loss leads to crossmodal plasticity in regions of the cerebrum that are dominated by acoustical processing in hearing subjects. Until recently, little has been known of the connectional basis of this phenomenon. One region whose crossmodal properties are well-established is the auditory field of the anterior ectosylvian sulcus (FAES) in the cat, where neurons are normally responsive to acoustic stimulation and its deactivation leads to the behavioral loss of accurate orienting toward auditory stimuli. However, in early-deaf cats, visual responsiveness predominates in the FAES and its deactivation blocks accurate orienting behavior toward visual stimuli. For such crossmodal reorganization to occur, it has been presumed that novel inputs or increased projections from non-auditory cortical areas must be generated, or that existing non-auditory connections were âunmasked.â These possibilities were tested using tracer injections into the FAES of adult cats deafened early in life (and hearing controls), followed by light microscopy to localize retrogradely labeled neurons. Surprisingly, the distribution of cortical and thalamic afferents to the FAES was very similar among early-deaf and hearing animals. No new visual projection sources were identified and visual cortical connections to the FAES were comparable in projection proportions. These results support an alternate theory for the connectional basis for cross-modal plasticity that involves enhanced local branching of existing projection terminals that originate in non-auditory as well as auditory cortices
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