2,655 research outputs found
CrĂ©ation dâun score dâĂ©valuation du risque de symptĂŽmes musculo-squelettiques basĂ© sur des facteurs professionnels
Objectif
Lâobjectif de ce travail est la crĂ©ation dâun score dâĂ©valuation du risque de symptĂŽmes musculo-squelettiques (SMS) chroniques des membres supĂ©rieurs, uniquement basĂ© sur des donnĂ©es dâexposition professionnelle aux dĂ©terminants biomĂ©caniques, psychosociaux et organisationnels. Ce score ne prenant pas en compte les facteurs individuels, permettra de classer les situations de travail devant bĂ©nĂ©ficier dâune action de prĂ©vention.
MĂ©thodes
LâĂ©chantillon dâĂ©tude Ă©tait constituĂ© de 1749 salariĂ©s recrutĂ©s lors de la phase dâinclusion de la cohorte des salariĂ©s ligĂ©riens (COSALI). Les facteurs organisationnels, biomĂ©caniques et psychosociaux et les variables associĂ©es aux SMS chroniques ont Ă©tĂ© recueillis par auto-questionnaire. Un score a Ă©tĂ© crĂ©Ă© selon trois mĂ©thodes statistiques : une rĂ©gression logistique binaire, une analyse en clusters suivie dâune analyse par arbre de dĂ©cision et une modĂ©lisation par classes latentes. Chacune de ces mĂ©thodes est susceptible dâentraĂźner la crĂ©ation de scores diffĂ©rents.
RĂ©sultats
Lâarea under the curve (AUC) obtenu par la rĂ©gression logistique Ă©tait de 0,75 contre 0,66 pour lâanalyse en clusters et 0,65 pour lâanalyse en classes latentes. La rĂ©gression logistique a donc Ă©tĂ© retenue pour la crĂ©ation du score. Les facteurs associĂ©s aux SMS chroniques des membres supĂ©rieurs Ă©taient lâintensitĂ© Ă©levĂ©e des efforts physiques ressentie (Ă©chelle RPE de Borg), la rĂ©pĂ©titivitĂ© des gestes plus de 4 h/j, la flexion du coude plus de 2 h/j, lâutilisation de la pince pouce-index plus de 4 h/j, la possibilitĂ© dâinfluencer le dĂ©roulement de son travail et lâaide des collĂšgues. Le score a ensuite Ă©tĂ© crĂ©Ă© Ă partir des paramĂštres estimĂ©s de la rĂ©gression logistique, il sâĂ©tend de â1 à 15. Par exemple, 66 % de lâĂ©chantillon a un score supĂ©rieur ou Ă©gal Ă deux. Pour ce seuil, la valeur prĂ©dictive nĂ©gative est de 93,4 %.
Conclusions
Selon le seuil choisi, le score aboutit Ă une forte valeur prĂ©dictive nĂ©gative. Il pourrait constituer un outil utile aux prĂ©venteurs en entreprise afin de cibler lâeffectif pour lequel il nâest pas indispensable de mettre en place des actions de prĂ©vention. NĂ©anmoins ce score ne permet pas de prĂ©dire avec confiance les salariĂ©s qui seront atteints de SMS. Pour avoir un score plus performant, il faudrait intĂ©grer des facteurs individuels tels que lâĂąge et le sexe, mais la caractĂ©risation par situation de travail nâest alors plus envisageable
Nutrients
Vitamin K participates in brain physiology. This study aimed to determine whether using vitamin K antagonists (VKAs), which interfere with the vitamin K cycle, were (i) cross-sectionally associated with altered cognitive performance, and (ii) independent predictors of cognitive changes in older adults over 24 months. Information was collected on the use of VKAs (i.e., warfarin, acenocoumarol, and fluindione) among 378 geriatric outpatients (mean, 82.3 +/- 5.6 years; 60.1% female). Global cognitive performance and executive functions were assessed with Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB) scores, respectively, at baseline and after 12 and 24 months of follow-up. Age, gender, body mass index, mean arterial pressure, disability, gait speed, comorbidities, atrial fibrillation, stroke, carotid artery stenosis, leukoaraiosis grade on computed tomography (CT) scan, psychoactive drugs, antidementia drugs, blood-thinning drugs (i.e., anticoagulants other than VKAs, antiplatelet medications), serum creatinine levels, and vitamin B12 concentrations were considered as potential confounders. Using VKAs was associated with lower (i.e., worse) FAB score at baseline (adjusted beta = -2.1, p = 0.026), and with a decrease in FAB score after 24 months (adjusted beta = -203.6%, p = 0.010), but not after 12 months (p = 0.659). Using VKAs was not associated with any change in MMSE score at baseline (p = 0.655), after 12 months (p = 0.603), or after 24 months (p = 0.201). In conclusion, we found more severe executive dysfunction at baseline and incident executive decline over 24 months among geriatric patients using VKAs, when compared with their counterparts
AVHRR and VISSR satellite instrument calibration results for both Cirrus and marine stratocumulus IFO periods
Accurate characterizations of some cloud parameters are dependent upon the absolute accuracy of satellite radiance measurements. Visible wavelength measurements from both the AVHRR and VISSR instruments are often used to study cloud characteristics. Both of these instruments were radiometrically calibrated prior to launch, but neither has an onboard device to monitor degradation after launch. During the FIRE/SRB cirrus Intensive Field Operation (IFO), a special effort was made to monitor calibration of these two instruments onboard the NOAA-9 and GOES-6 spacecraft. In addition, several research groups have combined their efforts to assess the long-term performance of both instruments. These results are presented, and a limited comparison is made with the ERBE calibration standard
Anomalous material-dependent transport of focused, laser-driven proton beams.
Intense lasers can accelerate protons in sufficient numbers and energy that the resulting beam can heat materials to exotic warm (10âs of eV temperature) states. Here we show with experimental data that a laser-driven proton beam focused onto a target heated it in a localized spot with size strongly dependent upon material and as small as 35âÎŒm radius. Simulations indicate that cold stopping power values cannot model the intense proton beam transport in solid targets well enough to match the large differences observed. In the experiment a 74 J, 670âfs laser drove a focusing proton beam that transported through different thicknesses of solid Mylar, Al, Cu or Au, eventually heating a rear, thin, Au witness layer. The XUV emission seen from the rear of the Au indicated a clear dependence of proton beam transport upon atomic number, Z, of the transport layer: a larger and brighter emission spot was measured after proton transport through the lower Z foils even with equal mass density for supposed equivalent proton stopping range. Beam transport dynamics pertaining to the observed heated spot were investigated numerically with a particle-in-cell (PIC) code. In simulations protons moving through an Al transport layer result in higher Au temperature responsible for higher Au radiant emittance compared to a Cu transport case. The inferred finding that proton stopping varies with temperature in different materials, considerably changing the beam heating profile, can guide applications seeking to controllably heat targets with intense proton beams
Pay What You Want as a Marketing Strategy in Monopolistic and Competitive Markets
Pay What You Want (PWYW) can be an attractive marketing strategy to price discriminate between fair-minded and selfish customers, to fully penetrate a market without giving away the product for free, and to undercut competitors that use posted prices. We report on laboratory experiments that identify causal factors determining the willingness of buyers to pay voluntarily under PWYW. Furthermore, to see how competition affects the viability of PWYW, we implement markets in which a PWYW seller competes with a traditional seller. Finally, we endogenize the market structure and let sellers choose their pricing strategy. The experimental results show that outcome-based social preferences and strategic considerations to keep the seller in the market can explain why and how much buyers pay voluntarily to a PWYW seller. We find that PWYW can be viable in isolation, but it is less successful as a competitive strategy because it does not drive traditional posted-price sellers out of the market. Instead, the existence of a posted-price competitor reduces buyersâ payments and prevents the PWYW seller from fully penetrating the market. If given the choice, the majority of sellers opt for setting a posted price rather than a PWYW pricing. We discuss the implications of these results for the use of PWYW as a marketing strategy
Magnetic Phase Diagram and Metal-Insulator Transition of NiS2-xSex
Magnetic phase diagram of NiS2-xSex has been reexamined by systematic studies
of electrical resistivity, uniform magnetic susceptibility and neutron
diffraction using single crystals grown by a chemical transport method. The
electrical resistivity and the uniform magnetic susceptibility exhibit the same
feature of temperature dependence over a wide Se concentration. A distinct
first order metal-insulator (M-I) transition accompanied by a volume change was
observed only in the antiferromagnetic ordered phase for 0.50<x<0.59. In this
region, the M-I transition makes substantial effects to the thermal evolution
of staggered moments. In the paramagnetic phase, the M-I transition becomes
broad; both the electrical resistivity and the uniform magnetic susceptibility
exhibit a broad maximum around the temperatures on the M-I transition-line
extrapolated to the paramagnetic phase.Comment: 6 pages, 8 figures, corrected EPS fil
Quantum Impurities and the Neutron Resonance Peak in : Ni versus Zn
The influence of magnetic (S=1) and nonmagnetic (S=0) impurities on the spin
dynamics of an optimally doped high temperature superconductor is compared in
two samples with almost identical superconducting transition temperatures:
YBa(CuNi)O (T=80 K) and
YBa(CuZn)O (T=78 K). In the Ni-substituted
system, the magnetic resonance peak (which is observed at E40 meV in
the pure system) shifts to lower energy with a preserved E/T ratio
while the shift is much smaller upon Zn substitution. By contrast Zn, but not
Ni, restores significant spin fluctuations around 40 meV in the normal state.
These observations are discussed in the light of models proposed for the
magnetic resonance peak.Comment: 3 figures, submitted to PR
The low level of debris disk activity at the time of the Late Heavy Bombardment: a Spitzer study of Praesepe
We present 24 micron photometry of the intermediate-age open cluster
Praesepe. We assemble a catalog of 193 probable cluster members that are
detected in optical databases, the Two Micron All Sky Survey (2MASS), and at 24
micron, within an area of ~ 2.47 square degrees. Mid-IR excesses indicating
debris disks are found for one early-type and for three solar-type stars.
Corrections for sampling statistics yield a 24 micron excess fraction (debris
disk fraction) of 6.5 +- 4.1% for luminous and 1.9 +- 1.2% for solar-type
stars. The incidence of excesses is in agreement with the decay trend of debris
disks as a function of age observed for other cluster and field stars. The
values also agree with those for older stars, indicating that debris generation
in the zones that emit at 24 micron falls to the older 1-10 Gyr field star
sample value by roughly 750 Myr.
We discuss our results in the context of previous observations of excess
fractions for early- and solar-type stars. We show that solar-type stars lose
their debris disk 24 micron excesses on a shorter timescale than early-type
stars. Simplistic Monte Carlo models suggest that, during the first Gyr of
their evolution, up to 15-30% of solar-type stars might undergo an orbital
realignment of giant planets such as the one thought to have led to the Late
Heavy Bombardment, if the length of the bombardment episode is similar to the
one thought to have happened in our Solar System.
In the Appendix, we determine the cluster's parameters via boostrap Monte
Carlo isochrone fitting, yielding an age of 757 Myr (+- 36 Myr at 1 sigma
confidence) and a distance of 179 pc (+- 2 pc at 1 sigma confidence), not
allowing for systematic errors.Comment: 22 pages, 14 figures, 9 tables, emulateapj format; Accepted for
publication in The Astrophysical Journa
Kondo screening of the spin and orbital magnetic moments of Fe impurities in Cu
We use x-ray magnetic circular dichroism to evidence the effect of correlations on the local impurity magnetic moment in an archetypal Kondo system, namely, a dilute Cu:Fe alloy. Applying the sum rules on the Fe L2,3 absorption edges, the evolution of the spin and orbital moments across the Kondo temperature are determined separately. The spin moment presents a crossover from a nearly temperature-independent regime below the Kondo temperature to a paramagneticlike regime above. Conversely, the weak orbital moment shows a temperature-independent behavior in the whole temperature range, suggesting different Kondo screening temperature scales for the spin and orbital moments
New Debris Disks Around Nearby Main Sequence Stars: Impact on The Direct Detection of Planets
Using the MIPS instrument on the Spitzer telescope, we have searched for
infrared excesses around a sample of 82 stars, mostly F, G, and K main-sequence
field stars, along with a small number of nearby M stars. These stars were
selected for their suitability for future observations by a variety of
planet-finding techniques. These observations provide information on the
asteroidal and cometary material orbiting these stars - data that can be
correlated with any planets that may eventually be found. We have found
significant excess 70um emission toward 12 stars. Combined with an earlier
study, we find an overall 70um excess detection rate of % for mature
cool stars. Unlike the trend for planets to be found preferentially toward
stars with high metallicity, the incidence of debris disks is uncorrelated with
metallicity. By newly identifying 4 of these stars as having weak 24um excesses
(fluxes 10% above the stellar photosphere), we confirm a trend found in
earlier studies wherein a weak 24um excess is associated with a strong 70um
excess. Interestingly, we find no evidence for debris disks around 23 stars
cooler than K1, a result that is bolstered by a lack of excess around any of
the 38 K1-M6 stars in 2 companion surveys. One motivation for this study is the
fact that strong zodiacal emission can make it hard or impossible to detect
planets directly with future observatories like the {\it Terrestrial Planet
Finder (TPF)}. The observations reported here exclude a few stars with very
high levels of emission, 1,000 times the emission of our zodiacal cloud,
from direct planet searches. For the remainder of the sample, we set relatively
high limits on dust emission from asteroid belt counterparts
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