917 research outputs found
Towards agent-based crowd simulation in airports using games technology
We adapt popular video games technology for an agent-based crowd simulation in an airport terminal. To achieve this, we investigate the unique traits of airports and implement a virtual crowd by exploiting a scalable layered intelligence technique in combination with physics middleware and a socialforces approach. Our experiments show that the framework runs at interactive frame-rate and evaluate the scalability with increasing number of agents demonstrating
navigation behaviour
Nonequilibrium entropy production for open quantum systems
We consider open quantum systems weakly coupled to a heat reservoir and
driven by arbitrary time-dependent parameters. We derive exact microscopic
expressions for the nonequilibrium entropy production and entropy production
rate, valid arbitrarily far from equilibrium. By using the two-point energy
measurement statistics for system and reservoir, we further obtain a quantum
generalization of the integrated fluctuation theorem put forward by Seifert
[PRL 95, 040602 (2005)].Comment: 4 pages, 1 figur
Lombalgie chronique, COTOREP et reclassement professionnel en Moselle
Objectifs : Décrire les caractéristiques, la prise en charge, les résultats et le coût d\u27un reclassement professionnel concernant les assurés mosellans lombalgiques chroniques bénéficiant d’un accord de la Commission technique d\u27orientation et de reclassement professionnel (COTOREP). Méthodes : Etude descriptive menée entre août 2000 et mars 2001 dans le cadre d\u27un partenariat avec la COTOREP de Moselle intégrant 48 lombalgiques chroniques pour lesquels la COTOREP a donné en 1995 un accord de pré-orientation ou de reclassement professionnels. Résultats : Le lombalgique pris en charge était un homme jeune, de faible niveau scolaire et professionnel, en rupture avec le milieu du travail et souffrant d\u27une pathologie lombaire invalidante. Sur 32 formations suivies, 24 candidats ont réussi leur examen mais seuls dix diplômés ont trouvé un emploi. Huit diplômés ont trouvé un emploi conforme à la formation apprise. Le taux de reprise du travail était semblable pour les diplômés (10/24) et pour les autres lombalgiques (11/24). Le coût global pour l\u27assurance maladie variait de 25 000 en externat à 39 000 en internat. Conclusion : Devant la faible valeur ajoutée du reclassement professionnel que nous avons constatée, il paraît souhaitable de maintenir le lombalgique chronique dans son emploi en restaurant son rachis, en aménageant son poste de travail et, surtout, en gérant ses peurs et croyances liées au couple lombalgietravail
Magnetoresistance Effects in SrFeO(3-x): Dependence on Phase Composition and Relation to Magnetic and Charge Order
Single crystals of iron(IV) rich oxides SrFeO(3-x) with controlled oxygen
content have been studied by Moessbauer spectroscopy, magnetometry,
magnetotransport measurements, Raman spectroscopy, and infrared ellipsometry in
order to relate the large magnetoresistance (MR) effects in this system to
phase composition, magnetic and charge order. It is shown that three different
types of MR effects occur. In cubic SrFeO3 (x = 0) a large negative MR of 25%
at 9 T is associated with a hitherto unknown 60 K magnetic transition and a
subsequent drop in resistivity. The 60 K transition appears in addition to the
onset of helical ordering at ~130 K. In crystals with vacancy-ordered
tetragonal SrFeO(3-x) as majority phase (x ~0.15) a coincident
charge/antiferromagnetic ordering transition near 70 K gives rise to a negative
giant MR effect of 90% at 9 T. A positive MR effect is observed in tetragonal
and orthorhombic materials with increased oxygen deficiency (x = 0.19, 0.23)
which are insulating at low temperatures. Phase mixtures can result in a
complex superposition of these different MR phenomena. The MR effects in
SrFeO(3-x) differ from those in manganites as no ferromagnetic states are
involved
General Non-equilibrium Theory of Colloid Dynamics
A non-equilibrium extension of Onsager's canonical theory of thermal
fluctuations is employed to derive a self-consistent theory for the description
of the statistical properties of the instantaneous local concentration profile
n(r,t) of a colloidal liquid in terms of the coupled time evolution equations
of its mean value n(r,t) and of the covariance {\sigma}(r,r';t) \equiv
of its fluctuations {\delta}n(r, t) = n(r, t) -
n(r, t). These two coarse-grained equations involve a local mobility function
b(r, t) which, in its turn, is written in terms of the memory function of the
two-time correlation function C(r, r' ; t, t') \equiv <{\delta}n(r,
t){\delta}n(r',t')>. For given effective interactions between colloidal
particles and applied external fields, the resulting self-consistent theory is
aimed at describing the evolution of a strongly correlated colloidal liquid
from an initial state with arbitrary mean and covariance n^0(r) and
{\sigma}^0(r,r') towards its equilibrium state characterized by the equilibrium
local concentration profile n^(eq)(r) and equilibrium covariance
{\sigma}^(eq)(r,r').
This theory also provides a general theoretical framework to describe
irreversible processes associated with dynamic arrest transitions, such as
aging, and the effects of spatial heterogeneities
Detection of human bocavirus in children with Kawasaki disease
ABSTRACTHuman bocavirus (HboV) is an emerging virus that has been implicated as a cause of acute upper and lower respiratory tract infection in children. As no serological assay is available, PCR was used to screen nasopharyngeal, serum or stool samples from 16 patients with Kawasaki disease for HBoV nucleic acid. HBoV was identified by PCR in five (31.2%) patients, suggesting that this emerging virus may also play a pathogenic role in some cases of Kawasaki disease
Why did Swiss citizens vote to ban tobacco advertising?
In February 2022, Swiss citizens agreed to modify the Swiss Constitution to ban tobacco advertising reaching children and adolescents. This case study analyses the arguments used by both opponents and supporters of the constitutional amendment. Opponents argued that the proposed regulation went too far, threatened the economy, restricted personal freedom, was superfluous as the current law already protected youth and that it opened the door to marketing bans of other harmful products. Proponents focused on youth protection and invoked the burden of smoking on public health and the fact that advertising bans are an effective evidence-based measure. A comparison with previous campaigns to ban tobacco advertising that had failed suggests factors accounting for the positive vote in 2022. These include the strategic framing of youth protection, the separation of tobacco from other issues (such as alcohol advertising), the deteriorating image of the tobacco industry and the ability of the proponents to mobilise a broad coalition of health and youth organisations, with improved funding and communication. The lessons may be instructive for other campaigns seeking to regulate commercial determinants of health
Molecular dynamics simulation of aqueous solutions of 26-unit segments of p(NIPAAm) and of p(NIPAAm) "doped" with amino acid based comonomers
We have performed 75-ns molecular dynamics (MD) simulations of aqueous solutions of a 26-unit NIPAAm
oligomer at two temperatures, 302 and 315 K, below and above the experimentally determined lower critical
solution temperature (LCST) of p(NIPAAm). We have been able to show that at 315 K the oligomer assumes
a compact form, while it keeps a more extended form at 302 K. A similar behavior has been demonstrated
for a similar NIPAAm oligomer, where two units had been substituted by methacryloyl-l-valine (MAVA)
comonomers, one of them being charged and one neutral. For another analogous oligomer, where the same
units had been substituted by methacryloyl-l-leucine (MALEU) comonomers, no transition from the extended
to the more compact conformation has been found within the same simulation time. Statistical analysis of the
trajectories indicates that this transition is related to the dynamics of the oligomer backbone, and to the formation
of intramolecular hydrogen bonds and water-bridges between distant units of the solute. In the MAVA case,
we have also evidenced an important role of the neutral MAVA comonomer in stabilizing the compact coiled
structure. In the MALEU case, the corresponding comonomer is not equally efficacious and, possibly, is
even hindering the readjustment of the oligomer backbone. Finally the self-diffusion coefficient of water
molecules surrounding the oligomers at the two temperatures for selected relevant times is observed to
characteristically depend on the distance from the solute molecules
Square cells in gravitational and capillary thermoconvection
The onset of square convective cells in fluid layers heated from below is investigated. Amplitude equations an deduced from the Boussinesq equations and a standard stability analysis is performed. Square cells are shown to be preferred when the instability is mainly capillarity driven. The influence of the Prandtl and Blot numbers are examined. At small Pr, the Plot number has not very much influence and squares are always observed for thin enough layers. in large Prandtl number fluids, Pi must be larger than the limiting value 0.28 for squares to be stable
Test of mode coupling theory for a supercooled liquid of diatomic molecules. II. q-dependent orientational correlators
Using molecular dynamics computer simulations we study the dynamics of a
molecular liquid by means of a general class of time-dependent correlators
S_{ll'}^m(q,t) which explicitly involve translational (TDOF) and orientational
degrees of freedom (ODOF). The system is composed of rigid, linear molecules
with Lennard- Jones interactions. The q-dependence of the static correlators
S_{ll'}^m(q) strongly depend on l, l' and m. The time dependent correlators are
calculated for l=l'. A thorough test of the predictions of mode coupling theory
(MCT) is performed for S_{ll}^m(q,t) and its self part S_{ll}^{(s)m}(q,t), for
l=1,..,6. We find a clear signature for the existence of a single temperature
T_c, at which the dynamics changes significantly. The first scaling law of MCT,
which involves the critical correlator G(t), holds for l>=2, but no critical
law is observed. Since this is true for the same exponent parameter lambda as
obtained for the TDOF, we obtain a consistent description of both, the TDOF and
ODOF, with the exception of l=1. This different behavior for l \ne 1 and l=1
can also be seen from the corresponding susceptibilities
(chi'')_{ll}^m(q,omega) which exhibit a minimum at about the same frequency
omega_{min} for all q and all l \ne 1, in contrast to (chi'')_{11}^m(q,omega)
for which omega'_{min} approx 10 omega_{min} . The asymptotic regime, for which
the first scaling law holds, shrinks with increasing l. The second scaling law
of MCT (time-temperature superposition principle) is reasonably fulfilled for l
\ne 1 but not for l=1. Furthermore we show that the q- and (l,m)-dependence of
the self part approximately factorizes, i.e. S_{ll}^{(s)m}(q,t) \cong
C_l^{(s)}(t) F_s(q,t) for all m.Comment: 11 pages of RevTex, 16 figure
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