3,409 research outputs found
Thulium and ytterbium-doped titanium oxide thin films deposited by ultrasonic spray pyrolysis
Thin films of thulium and ytterbium-doped titanium oxide were grown by
metal-organic spray pyrolysis deposition from titanium(IV)oxide
bis(acetylacetonate), thulium(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate)
and ytterbium(III) tris(acetylacetonate). Deposition temperatures have been
investigated from 300{\deg}C to 600{\deg}C. Films have been studied regarding
their crystallity and doping quality. Structural and composition
characterisations of TiO2:Tm,Yb were performed by electron microprobe, X-ray
diffraction and Fourier transform infrared spectroscopy. The deposition rate
can reach 0.8 \mum/h. The anatase phase of TiO2 was obtained after synthesis at
400{\deg}C or higher. Organic contamination at low deposition temperature is
eliminated by annealing treatments.Comment: 6 pages, 6 figure
SPOT4 Management Centre
In the context of the CNES SPOT4 program CISI is particularly responsible for the development of the SPOT4 Management Centre, part of the SPOT4 ground control system located at CNES Toulouse (France) designed to provide simultaneous control over two satellites. The main operational activities are timed to synchronize with satellite visibilities (ten usable passes per day). The automatic capability of this system is achieved through agenda services (sequence of operations as defined and planned by operator). Therefore, the SPOT4 Management Centre offers limited, efficient and secure human interventions for supervision and decision making. This paper emphasizes the main system characteristics as degree of automation, level of dependability and system parameterization
Mitochondrial uncoupling as a regulator of life-history trajectories in birds: an experimental study in the zebra finch.
Mitochondria have a fundamental role in the transduction of energy from food into ATP. The coupling between food oxidation and ATP production is never perfect, but may nevertheless be of evolutionary significance. The 'uncoupling to survive' hypothesis suggests that 'mild' mitochondrial uncoupling evolved as a protective mechanism against the excessive production of damaging reactive oxygen species (ROS). Because resource allocation and ROS production are thought to shape animal life histories, alternative life-history trajectories might be driven by individual variation in the degree of mitochondrial uncoupling. We tested this hypothesis in a small bird species, the zebra finch (Taeniopygia guttata), by treating adults with the artificial mitochondrial uncoupler 2,4-dinitrophenol (DNP) over a 32-month period. In agreement with our expectations, the uncoupling treatment increased metabolic rate. However, we found no evidence that treated birds enjoyed lower oxidative stress levels or greater survival rates, in contrast to previous results in other taxa. In vitro experiments revealed lower sensitivity of ROS production to DNP in mitochondria isolated from skeletal muscles of zebra finch than mouse. In addition, we found significant reductions in the number of eggs laid and in the inflammatory immune response in treated birds. Altogether, our data suggest that the 'uncoupling to survive' hypothesis may not be applicable for zebra finches, presumably because of lower effects of mitochondrial uncoupling on mitochondrial ROS production in birds than in mammals. Nevertheless, mitochondrial uncoupling appeared to be a potential life-history regulator of traits such as fecundity and immunity at adulthood, even with food supplied ad libitum
Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei
We report on direct time-of-flight based mass measurements of 16 light
neutron-rich nuclei. These include the first determination of the masses of the
Borromean drip-line nuclei B, C and F as well as that of
Na. In addition, the most precise determinations to date for N
and Ne are reported. Coupled with recent interaction cross-section
measurements, the present results support the occurrence of a two-neutron halo
in C, with a dominant configuration, and a
single-neutron halo in Ne with the valence neutron occupying
predominantly the 2 orbital. Despite a very low two-neutron separation
energy the development of a halo in B is hindered by the 1
character of the valence neutrons.Comment: 5 page
Probing pre-formed alpha particles in the ground state of nuclei
In this Letter, we report on alpha particle emission through the nuclear
break-up in the reaction 40Ca on a 40Ca target at 50A MeV. It is observed that,
similarly to nucleons, alpha particles can be emitted to the continuum with
very specific angular distribution during the reaction. The alpha particle
properties can be understood as resulting from an alpha cluster in the daughter
nucleus that is perturbed by the short range nuclear attraction of the
collision partner and emitted. A time-dependent theory that describe the alpha
particle wave-function evolution is able to reproduce qualitatively the
observed angular distribution. This mechanism offers new possibilities to study
alpha particle properties in the nuclear medium.Comment: 4 pages, 3 figure
Low skin temperature impairs the cutaneous vasodilator response to local progressive pressure strain.
A pressure-induced vasodilation (PIV) was recently reported as a putative protective response in human skin. Therefore, we examined the influence of skin temperatures on cutaneous blood flow responses to local progressive pressure strain. Ten healthy volunteers were studied at different ambient temperatures leading to low (29.0 +/- 0.3 degrees C), intermediate (32.6 +/- 0.1 degrees C), high (33.9 +/- 0.1 degrees C) and very high (36.0 +/- 0.1 degrees C) skin temperatures. We measured cutaneous blood flow using laser Doppler flowmetry on the foot in response to a local progressive pressure increase of 5.0 mm Hg min(-1). Progressive pressure strain led to an almost linear cutaneous laser Doppler flow decrease at both low and intermediate skin temperatures (-40.1 +/- 6.6% and -31.2 +/- 6.5% from baseline at 30 +/- 1.25 mm Hg), whereas at both high and very high skin temperatures, subjects responded with a transient cutaneous vasodilation (+33.6 +/- 10.6% and +50.6 +/- 15.4% from baseline at 30 +/- 1.25 mm Hg). These findings suggest that high skin temperatures are required for the PIV to develop
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
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