158 research outputs found
Douleurs et travail : aider le patient à garder un emploi
Introduction.— A significant part of the workers suffer from musculoskeletal pain (back pain,upper limb). Some of them are at risk to ose their job due to their health condition.
Objective. — The aim of the article is to describe synthetically what actors and measure can be used in order to help a patient keep his/her job in spite of the pain.
Results.— First place measures include a visit with the occupational physician before work resumption, part-time return to work and workplace accommodation.Second place measures require that a professional project is built by the patient supported by a knowledgeable person. These measures depend on the funding agency.They are devoted to compensate the work disability situation, and/or to provide the training required by the patient’s project.
Discussion and conclusion. — Work disability prevention faces many challenges due to barriers between the stakeholders, scattering of the knowledge and the complexity of legislative issues.However, it remains possible provided the patient is committed and supported by a case manager in charge of coordinating the information and the stakeholders. Confidence and collaboration are key issues in the process.
Non-monotonic field-dependence of the ZFC magnetization peak in some systems of magnetic nanoparticles
We have performed magnetic measurements on a diluted system of gamma-Fe2O3
nanoparticles (~7nm), and on a ferritin sample. In both cases, the ZFC-peak
presents a non-monotonic field dependence, as has already been reported in some
experiments,and discussed as a possible evidence of resonant tunneling. Within
simple assumptions, we derive expressions for the magnetization obtained in the
usual ZFC, FC, TRM procedures. We point out that the ZFC-peak position is
extremely sensitive to the width of the particle size distribution, and give
some numerical estimates of this effect. We propose to combine the FC
magnetization with a modified TRM measurement, a procedure which allows a more
direct access to the barrier distribution in a field. The typical barrier
values which are obtained with this method show a monotonic decrease for
increasing fields, as expected from the simple effect of anisotropy barrier
lowering, in contrast with the ZFC results. From our measurements on
gamma-Fe2O3 particles, we show that the width of the effective barrier
distribution is slightly increasing with the field, an effect which is
sufficient for causing the observed initial increase of the ZFC-peak
temperatures.Comment: LaTeX file 19 pages, 9 postscript figures. To appear in Phys. Rev. B
(tentative schedule: Dec.97
By design : negotiating flexible learning in the built environment discipline
The term ‘flexible education’ is now firmly entrenched within Australian higher education discourse, yet the term is a contested one imbued with a multiplicity of meanings. This paper describes a process designed to elucidate how the idea of flexible education can be translated into teaching models that are informed by the specific demands of disciplinary contexts. The process uses a flexible learning ‘matching’ tool to articulate the understandings and preferences of students and academics of the Built Environment to bridge the gap between student expectations of flexibility and their teacher’s willingness and ability to provide that flexibility within the limits of the pedagogical context and teaching resources. The findings suggest an informed starting point for educators in the Built Environment and other creative disciplines from which to traverse the complexities inherent in negotiating flexibility in an increasingly digital world
Relaxation and Landau-Zener experiments down to 100 mK in ferritin
Temperature-independent magnetic viscosity in ferritin has been observed from
2 K down to 100 mK, proving that quantum tunneling plays the main role in these
particles at low temperature. Magnetic relaxation has also been studied using
the Landau-Zener method making the system crossing zero resonant field at
different rates, alpha=dH/dt, ranging from 10^{-5} to 10^{-3} T/s, and at
different temperatures, from 150 mK up to the blocking temperature. We propose
a new Tln(Delta H_{eff}/tau_0 alpha) scaling law for the Landau-Zener
probability in a system distributed in volumes, where Delta H_{eff} is the
effective width of the zero field resonance.Comment: 13 pages, 4 postscript figure
Real-time non-equilibrium dynamics of quantum glassy systems
We develop a systematic analytic approach to aging effects in quantum
disordered systems in contact with an environment. Within the closed-time
path-integral formalism we include dissipation by coupling the system to a set
of independent harmonic oscillators that mimic a quantum thermal bath. After
integrating over the bath variables and averaging over disorder we obtain an
effective action that determines the real-time dynamics of the system. The
classical limit yields the Martin-Siggia-Rose generating functional associated
to a colored noise. We apply this general formalism to a prototype model
related to the spin-glass. We show that the model has a dynamic phase
transition separating the paramagnetic from the spin-glass phase and that
quantum fluctuations depress the transition temperature until a quantum
critical point is reached. We show that the dynamics in the paramagnetic phase
is stationary but presents an interesting crossover from a region controlled by
the classical critical point to another one controlled by the quantum critical
point. The most characteristic property of the dynamics in a glassy phase,
namely aging, survives the quantum fluctuations. In the sub-critical region the
quantum fluctuation-dissipation theorem is modified in a way that is consistent
with the notion of effective temperatures introduced for the classical case. We
discuss these results in connection with recent experiments in dipolar quantum
spin-glasses and the relevance of the effective temperatures with respect to
the understanding of the low temperature dynamics.Comment: 56 pages, Revtex, 17 figures include
Retrieving C and O Abundance of HR 8799 c by Combining High- and Low-Resolution Data
The formation and evolution pathway for the directly-imaged multi-planetary
system HR 8799 remains mysterious. Accurate constraints on the chemical
composition of the planetary atmosphere(s) are key to solving the mystery. We
perform a detailed atmospheric retrieval on HR 8799~c to infer the chemical
abundances and abundance ratios using a combination of photometric data along
with low- and high-resolution spectroscopic data (R20-35,000). We
specifically retrieve [C/H], [O/H], and C/O and find them to be
0.55, 0.47, and 0.67 at
68\% confidence. The super-stellar C and O abundances, yet a stellar C/O ratio,
reveal a potential formation pathway for HR 8799~c. Planet c, and likely the
other gas giant planets in the system, formed early on (likely within 1
Myr), followed by further atmospheric enrichment in C and O through the
accretion of solids beyond the CO iceline. The enrichment either preceded or
took place during the early phase of the inward migration to the planet current
locations.Comment: 19 pages, 6 figures, 3 tables, accepted to AAS journal
Retrieving the C and O Abundances of HR 7672~AB: a Solar-Type Primary Star with a Benchmark Brown Dwarf
A benchmark brown dwarf (BD) is a BD whose properties (e.g., mass and
chemical composition) are precisely and independently measured. Benchmark BDs
are valuable in testing theoretical evolutionary tracks, spectral synthesis,
and atmospheric retrievals for sub-stellar objects. Here, we report results of
atmospheric retrieval on a synthetic spectrum and a benchmark BD -- HR 7672~B
-- with \petit. First, we test the retrieval framework on a synthetic PHOENIX
BT-Settl spectrum with a solar composition. We show that the retrieved C and O
abundances are consistent with solar values, but the retrieved C/O is
overestimated by 0.13-0.18, which is 4 times higher than the formal error
bar. Second, we perform retrieval on HR 7672~B using high spectral resolution
data (R=35,000) from the Keck Planet Imager and Characterizer (KPIC) and near
infrared photometry. We retrieve [C/H], [O/H], and C/O to be ,
, and . These values are consistent with those of HR
7672~A within 1.5-. As such, HR 7672~B is among only a few benchmark
BDs (along with Gl 570~D and HD 3651~B) that have been demonstrated to have
consistent elemental abundances with their primary stars. Our work provides a
practical procedure of testing and performing atmospheric retrieval, and sheds
light on potential systematics of future retrievals using high- and
low-resolution data.Comment: 29 pages, 17 figures, 5 tables, resubmitted to AAS journals after
first revisio
Cardiac lymphatics in health and disease
The lymphatic vasculature, which accompanies the blood vasculature in most organs, is indispensable in the maintenance of tissue fluid homeostasis, immune cell trafficking, and nutritional lipid uptake and transport, as well as in reverse cholesterol transport. In this Review, we discuss the physiological role of the lymphatic system in the heart in the maintenance of cardiac health and describe alterations in lymphatic structure and function that occur in cardiovascular pathology, including atherosclerosis and myocardial infarction. We also briefly discuss the role that immune cells might have in the regulation of lymphatic growth (lymphangiogenesis) and function. Finally, we provide examples of how the cardiac lymphatics can be targeted therapeutically to restore lymphatic drainage in the heart to limit myocardial oedema and chronic inflammation.Peer reviewe
Frontal GABA Levels Change during Working Memory
Functional neuroimaging metrics are thought to reflect changes in neurotransmitter flux, but changes in neurotransmitter levels have not been demonstrated in humans during a cognitive task, and the relationship between neurotransmitter dynamics and hemodynamic activity during cognition has not yet been established. We evaluate the concentration of the major inhibitory (GABA) and excitatory (glutamate + glutamine: Glx) neurotransmitters and the cerebral perfusion at rest and during a prolonged delayed match-to-sample working memory task. Resting GABA levels in the dorsolateral prefrontal cortex correlated positively with the resting perfusion and inversely with the change in perfusion during the task. Further, only GABA increased significantly during the first working memory run and then decreased continuously across subsequent task runs. The decrease of GABA over time was paralleled by a trend towards decreased reaction times and higher task accuracy. These results demonstrate a link between neurotransmitter dynamics and hemodynamic activity during working memory, indicating that functional neuroimaging metrics depend on the balance of excitation and inhibition required for cognitive processing
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