818 research outputs found
Tsallis statistics generalization of non-equilibrium work relations
We use third constraint formulation of Tsallis statistics and derive the
-statistics generalization of non-equilibrium work relations such as the
Jarzynski equality and the Crooks fluctuation theorem which relate the free
energy differences between two equilibrium states and the work distribution of
the non-equilibrium processes.Comment: 5 page
Li-decorated BC3 nanopores: Promising materials for hydrogen storage
In the quest of new absorbent for hydrogen storage, we investigate the
capacities of slit pores formed by two BC3 sheets decorated with Li atoms.
Their hydrogen storage capacities are determined using density-functional
theory in conjunction with a quantum-thermodynamic model that allows to
simulate real operating conditions, i.e., finite temperatures and different
loading and depletion pressures applied to the adsorbent in the charge-delivery
cycles. We show that the capacities of the adsorbed hydrogen phase of
Li-decorated BC3 slit pores are larger than those reported recently for
graphene and Li-decorated borophene slit pores. On the other hand, the usable
volumetric and gravimetric capacities of Li-decorated BC3 slit pores can meet
the targets stipulated by the U.S. Department of Energy (DOE) for onboard
hydrogen storage at moderate temperatures and loading pressures well below
those used in the tanks employed in current technology. In particular, the
usable volumetric capacity for pore widths of about 10 {\AA} meets the DOE
target at a loading pressure of 6.6 MPa when depleting at ambient pressure. Our
results highlight the important role played by the rotational degree of freedom
of the H2 molecule in determining the confining potential within the slip pores
and their hydrogen storage capacities.Comment: Article itself: 26 pages, 12 figures, 13 equations, 1 table, 78 cited
articles; Supporting information: 8 pages, 6 figures, 6 equation
Influence of surfactants on the structure of titanium oxide gels : experiments and simulations
We report here on experimental and numerical studies of the influence of
surfactants on mineral gel synthesis. The modification of the gel structure
when the ratios water-precursor and water-surfactant vary is brought to the
fore by fractal dimension measures. A property of {\em polydispersity of the
initial hydrolysis} is proposed to explain these results, and is successfuly
tested through numerical experiments of three dimensional chemically limited
aggregation.Comment: 12 pages, 4 Postscript figures, uses RevTe
Epidemiology and clinical features of gastroenteritis in hospitalised children: prospective survey during a 2-year period in a Parisian hospital, France
International audienceRotavirus is recognised as the most important agent of severe acute gastroenteritis (AGE) in young children. In a 2-year prospective survey, we investigated the epidemiology and clinical features of the viral and bacterial pathogens in children hospitalised for AGE. The study was performed in a Parisian teaching hospital from November 2001 to May 2004. Clinical data were prospectively collected to assess the gastroenteritis severity (20-point Vesikari severity score, the need for intravenous rehydration, duration of hospitalisation). Stools were systematically tested for group A rotavirus, norovirus, astrovirus and adenovirus 40/41, sapovirus and Aichi virus and enteropathogenic bacteria. A total of 457 children (mean age 15.9 months) were enrolled. Viruses were detected in 305 cases (66.7%) and bacteria in 31 cases (6.8%). Rotaviruses were the most frequent pathogen (48.8%), followed by noroviruses (8.3%) and adenoviruses, astroviruses, Aichi viruses and sapoviruses in 3.5%, 1.5%, 0.9% and 0.4%, respectively. Cases of rotavirus gastroenteritis were significantly more severe than those of norovirus with respect to the Vesikari score, duration of hospitalisation and the need for intravenous rehydration. Rotaviruses were the most frequent and most severe cause in children hospitalised for AGE, and noroviruses also account for a large number of cases in this population
Propylene Carbonate Reexamined: Mode-Coupling Scaling without Factorisation ?
The dynamic susceptibility of propylene carbonate in the moderately viscous
regime above is reinvestigated by incoherent neutron and
depolarised light scattering, and compared to dielectric loss and solvation
response. Depending on the strength of relaxation, a more or less
extended scaling regime is found. Mode-coupling fits yield consistently
and K, although different positions of the
susceptibility minimum indicate that not all observables have reached the
universal asymptotics
The Intestinal Microbiota Contributes to the Ability of Helminths to Modulate Allergic Inflammation
We thank Manuel Kulagin for technical help, Pierre Bonnaventure for portal vein blood sampling, Francisco Sepulveda for technical assistance in GS-MS acquisition, and Dorothee Hahne (Metabolomics Australia, University of Western Australia) for human samples SCFA isolation, acquisition, and analysis. We also thank Cristina Cartoni (Phenotyping Unit, EPFL) for Milliplex analysis, Jessica Dessimoz and her team from the Histology Core Facility (EPFL), Miguel Garcia and his team from the Flow Cytometry Core Facility (EPFL), and staff from the EPFL CPG animal house for excellent animal care. The computations were partially performed at the Vital-IT Center for high-performance computing of the SIB Swiss Institute of Bioinformatics (http://www.vital-it.ch). The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 310948. Funding for A.W.W. and a subset of the 16S rRNA gene sequencing was provided by the Wellcome Trust (grant number WT 098051). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Universal Static and Dynamic Properties of the Structural Transition in Pb(Zn1/3Nb2/3)O3
The relaxors Pb(ZnNb)O (PZN) and
Pb(MgNb)O (PMN) have very similar properties based on the
dielectric response around the critical temperature (defined by the
structural transition under the application of an electric field). It has been
widely believed that these materials are quite different below with the
unit cell of PMN remaining cubic while in PZN the low temperature unit cell is
rhombohedral in shape. However, this has been clarified by recent high-energy
x-ray studies which have shown that PZN is rhombohedral only in the skin while
the shape of the unit cell in the bulk is nearly cubic. In this study we have
performed both neutron elastic and inelastic scattering to show that the
temperature dependence of both the diffuse and phonon scattering in PZN and PMN
is very similar. Both compounds show a nearly identical recovery of the soft
optic mode and a broadening of the acoustic mode below . The diffuse
scattering in PZN is suggestive of an onset at the high temperature Burns
temperature similar to that in PMN. In contrast to PMN, we observe a broadening
of the Bragg peaks in both the longitudinal and transverse directions below
. We reconcile this additional broadening, not observed in PMN, in terms
of structural inhomogeneity in PZN. Based on the strong similarities between
PMN and PZN, we suggest that both materials belong to the same universality
class and discuss the relaxor transition in terms of the three-dimensional
Heisenberg model with cubic anisotropy in a random field.Comment: 11 pages, 10 figures. Updated version after helpful referee comment
Reorientational relaxation of a linear probe molecule in a simple glassy liquid
Within the mode-coupling theory (MCT) for the evolution of structural
relaxation in glass-forming liquids, correlation functions and susceptibility
spectra are calculated characterizing the rotational dynamics of a top-down
symmetric dumbbell molecule, consisting of two fused hard spheres immersed in a
hard-sphere system. It is found that for sufficiently large dumbbell
elongations, the dynamics of the probe molecule follows the same universal
glass-transition scenario as known from the MCT results of simple liquids. The
-relaxation process of the angular-index-j=1 response is stronger,
slower and less stretched than the one for j=2, in qualitative agreement with
results found by dielectric-loss and depolarized-light-scattering spectroscopy
for some supercooled liquids. For sufficiently small elongations, the
reorientational relaxation occurs via large-angle flips, and the standard
scenario for the glass-transition dynamics is modified for odd-j responses due
to precursor phenomena of a nearby type-A MCT transition. In this case, a major
part of the relaxation outside the transient regime is described qualitatively
by the -relaxation scaling laws, while the -relaxation scaling
law is strongly disturbed.Comment: 40 pages. 10 figures as GIF-files, to be published in Phys. Rev.
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
The opposite of Dante's hell? The transfer of ideas for social housing at international congresses in the 1850s–1860s
With the advent of industrialization, the question of developing adequate housing for the emergent working classes became more pressing than before. Moreover, the problem of unhygienic houses in industrial cities did not stop at the borders of a particular nation-state; sometimes literally as pandemic diseases spread out 'transnationally'. It is not a coincidence that in the nineteenth century the number of international congresses on hygiene and social topics expanded substantially. However, the historiography about social policy in general and social housing in particular, has often focused on individual cases because of the different pace of industrial and urban development and is thus dominated by national perspectives. In this paper, I elaborate on transnational exchange processes and local adaptations and transformations. I focus on the transfer of the housing model of SOMCO in Mulhouse, (a French house building association) during social international congresses. I examine whether cross-national networking enabled and facilitated the implementation of ideas on the local scale. I will elaborate on the transmission and the local adaptation of the Mulhouse-model in Belgium. Convergences, divergences, and different factors that influenced the local transformations (personal choice, political situation, socioeconomic circumstances) will be taken into accoun
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