Respiratory tract outbreak modeling with case definition criteria: A proposal for a standardized clinical approach in nursing homes.

OBJECTIVES: This study aimed to monitor respiratory tract outbreaks in nursing homes (NH) by applying standardized case definition criteria, pathogen identification and estimated mortality impact. PATIENTS AND METHODS: This longitudinal, observational study described NH outbreaks with temperature (T°), upper respiratory sign, lower respiratory sign (LRS), general status deterioration, general signs, and mortality. Viral examinations allowed for analysis of developing outbreaks based on positive, negative, or no tests (Flu+/Flu-/NT-Flu). RESULTS: Forty-six influenza identification episodes (Flu+, 1067 patients), 14 Flu- (409 patients), and 18 NT-Flu (381 patients) were analyzed. Viral examinations were conducted mainly among residents with T° (84.8% [302/356]). A specific temperature pattern was observed in Flu+ outbreaks: 35.1% of infected residents with T° without LRS, 15.6% in Flu- episodes, and 17.1% vs. 29.1% in LRS without T°. A median temperature (MT) of ≥38.3 °C was observed in Flu+ outbreaks. MT analysis of the 18 NT-Flu episodes identified five outbreaks with high temperatures (MT ≥38.2 °C) and high mortality. Conversely, the 13 NT-Flu outbreaks with lower MT (<38.0 °C) were associated with lower total mortality. Similar clinical pictures led to closely comparable all-cause mortality impacts, particularly in Flu+, Flu-, and NT-Flu with MT of ≥38.2 °C. CONCLUSIONS: Validated sign/symptom monitoring highlighted some specificities of respiratory NH outbreaks and could be a complementary approach, taking into account common and atypical clinical pictures, assessing mortality and initiating virological investigations and infection control measures.

Microreversibility and the statistics of currents in quantum transport.

For the statistics of currents in quantum transport, microreversibility is shown to provide a way to obtain the statistical cumulants at the order n+1 from the measurement of the cumulants at the order n or lower. This fundamental result is based on relations generalizing the fluctuation-dissipation theorem and the Onsager-Casimir reciprocal relations from linear toward nonlinear transport properties, as a consequence of the time-reversal symmetry of the underlying microscopic Hamiltonian dynamics. The method is demonstrated in detail in the case of multiterminal Aharonov-Bohm rings. Within the independent electron approximation, the cumulant generating function, which fully specifies the statistics of the nonequilibrium currents, is obtained from the scattering matrix of these circuits. The time-reversal symmetry relations are explicitly shown to express the cumulants at equilibrium up to the fourth order in terms of lower-order cumulants and their nonequilibrium responses in the presence of an external magnetic field.

Viral prevalence and laboratory investigations of gastroenteritis in institutions for dependent people.

OBJECTIVES: Viruses are recognized as important agents of gastroenteritis outbreaks in institutions caring for dependent people. We aimed to define norovirus (NoV) and rotavirus (RV) immunochromatographic tests (ICT) and reverse transcription-polymerase chain reaction (RT-PCR) used in gastroenteritis investigations. METHODS: Fourteen sites were monitored from 2010 to 2015, with 360 laboratory investigations. Twenty-two outbreaks and 44 sporadic case patients were investigated with ICTs (114 NoVs and 80 RVs) and RT-PCRs (114 NoVs and 52 RVs). RESULTS: ICTs were useful during outbreaks (identification of NoVs and RVs in respectively 76.5% and 75.0% of episodes) despite the NoV sensitivity limit (55.1%) and the four RV false positive results observed for 10 samples. Given the NoV ICT performance and the observed variations of the NoV and RV prevalence (between 20.0% and 5.0%), ICTs are not appropriate to identify sporadic gastroenteritis case patients. Positive predictive values <60.0% were observed when the prevalence of RV and NoV was low (<5.0%). NoV and RV RT-PCR indications are sporadic gastroenteritis case patients, negative NoV and RV ICT during outbreaks, control of positive RV ICT in cases of suspected NoV and RV co-circulation, patients with long symptom duration, and NoV genogroup and genotype identifications (infection control and epidemiological surveillance). Inclusion of patients with specific clinical symptoms is recommended irrespective of the technique. CONCLUSION: On the basis of the ICT limits identified in this work, RT-PCR development seems essential to improve viral gastroenteritis investigations in institutions caring for dependent people.

The role of fluctuations in bistability and oscillations during the H2 + O2 reaction on nanosized rhodium crystals.

A combined experimental and theoretical study is presented of fluctuations observed by field ion microscopy in the catalytic reaction of water production on a rhodium tip. A stochastic approach is developed to provide a comprehensive understanding of the different phenomena observed in the experiment, including burst noise manifesting itself in a bistability regime, noisy oscillations, and nanopatterns with a cross-like oxidized zone separating the surface into four quadrants centered on the {111} facets. The study is based on a stochastic model numerically simulating the processes of adsorption, desorption, reaction, and transport. The surface diffusion of hydrogen is described as a percolation process dominated by large clusters corresponding to the four quadrants. The model reproduces the observed phenomena in the ranges of temperature, pressures, and electric field of the experiment.

Burden of gastroenteritis outbreaks: specific epidemiology in a cohort of institutions caring for dependent people.

BACKGROUND: In institutions caring for dependent people, viral gastroenteritis occurs frequently and is highly contagious. In elderly persons, these episodes can lead to hospitalization and occasionally death. AIM: To study the impact of gastroenteritis outbreaks (GOs) in institutions caring for dependent people. METHODS: This study was conducted on 18 sites consisting of 35 units from four different disciplines (geriatric medicine and rehabilitation, psychogeriatrics, geriatric nursing homes, and specialized care homes for adults with physical and mental disabilities). Spatio-temporal analysis of GOs was performed during six winter seasons, and clinical and viral data were analysed with regard to structural parameters (size of the sites and dining-room organization), virus epidemiology and chronology of the outbreaks and type of activities. RESULTS: A total of 98 outbreaks were recorded in the 35 units. The risk of GO was high even outside national epidemic periods. Viruses were searched for in 86 outbreaks and were identified in 96.5% (83/86) of these outbreaks: norovirus genotype GII.4 (59.0%, 49/83), other viruses (41.0%, 34/83). There were variations between surveillance periods in terms of GO frequencies and attack rates and types of viruses. Dining-room organization could be a factor in cross-infection at a site. CONCLUSION: Specific surveillance that takes into account the precise epidemiology needs to be developed in institutions caring for dependent people in order to improve infectious disease control and information for healthcare workers.

Isometric fluctuation relations for equilibrium states with broken symmetry.

We derive a set of isometric fluctuation relations, which constrain the order parameter fluctuations in finite-size systems at equilibrium and in the presence of a broken symmetry. These relations are exact and should apply generally to many condensed-matter physics systems. Here, we establish these relations for magnetic systems and nematic liquid crystals in a symmetry-breaking external field, and we illustrate them on the Curie-Weiss and the XY models. Our relations also have implications for spontaneous symmetry breaking, which are discussed.

Kinetics and thermodynamics of first-order Markov chain copolymerization.

We report a theoretical study of stochastic processes modeling the growth of first-order Markov copolymers, as well as the reversed reaction of depolymerization. These processes are ruled by kinetic equations describing both the attachment and detachment of monomers. Exact solutions are obtained for these kinetic equations in the steady regimes of multicomponent copolymerization and depolymerization. Thermodynamic equilibrium is identified as the state at which the growth velocity is vanishing on average and where detailed balance is satisfied. Away from equilibrium, the analytical expression of the thermodynamic entropy production is deduced in terms of the Shannon disorder per monomer in the copolymer sequence. The Mayo-Lewis equation is recovered in the fully irreversible growth regime. The theory also applies to Bernoullian chains in the case where the attachment and detachment rates only depend on the reacting monomer.

Effect of ultrafast diffusion on adsorption, desorption, and reaction processes over heterogeneous surfaces.

The effect of ultrafast diffusion is studied on reaction-diffusion processes in heterogeneous media, as encountered in catalysis and field emission microscopy. The reaction-diffusion equations describe adsorption, desorption, and reaction processes for two adspecies, for instance, on a paraboloidal heterogeneous surface in the presence of an external electric field. Using multiscale analysis, we show that the fast adspecies rapidly reaches a quasiequilibrium spatial distribution, characterized by a nonequilibrium chemical potential of the fast adspecies. An ordinary differential equation is derived for the time evolution of the nonequilibrium chemical potential. Numerical simulations are performed under different conditions, which confirm the convergence of the dynamics for finite diffusion toward the ultrafast diffusion limit predicted by our multiscale analysis. The numerical simulations also demonstrate that electric fields may induce important diffusive currents on heterogeneous surfaces under the conditions of field emission microscopy.

[Clusters of respiratory tract infections and alert strategy in nursing homes]. / Cas groupés d'infections respiratoires aiguës et stratégie d'alerte en institutions de personnes âgées.

OBJECTIVE: Outbreaks of acute respiratory infections (ARI) are common in institutions for elderly people. We had for objective to investigate clusters of cases (lower respiratory tract infection and influenza-like illness [LRTI/ILI]) in order to improve and validate alert strategies in these institutions. METHODOLOGY: Prospective surveillance for LRTI/ILI was implemented in 11 institutions in Alsace, over five years. Clinical criteria were used to identify infected residents and clusters. Nasopharyngeal swabs were collected and rapid tests (Immunoassay) were performed to identify the influenza virus. RESULTS: The three week periods were analyzed if three cases or more were recorded during the first week. This analysis demonstrated an important risk of epidemic when this number of cases was reached in healthcare units. The influenza virus (10 clusters) and respiratory syncytial virus ([RSV], two clusters) were identified. CONCLUSION: The authors confirmed and emphasized the importance of adequate surveillance for clusters of respiratory tract infection cases. Early identification of an outbreak (three cases) is an important point to prevent transmission, especially during epidemic periods and if a virus is identified in the unit or institution.

Catalytic reduction of NO2 with hydrogen on Pt field emitter tips: kinetic instabilities on the nanoscale.

The catalytic reduction of NO(2) with hydrogen on a Pt field emitter tip is investigated using both field electron microscopy (FEM) and field ion microscopy (FIM). A rich variety of nonlinear behavior and unusually high catalytic activity around the {012} facets are observed. Our FEM investigations reveal that the correlation function exhibits damped oscillations with a decaying envelope, showing that molecular noise will influence the dynamics of the oscillations. The dependence of the oscillatory period on the P(H(2))/P(NO(2)) pressure ratios is analyzed. Similar patterns are reported under FIM conditions. Corresponding density functional theory (DFT) calculations for the adsorption of NO(2) on Pt{012} in the presence of an external electric field are performed in order to gain an atomistic understanding of the underlying nonlinear phenomena.

Interaction between silver nanowires and CO on a stepped platinum surface.

We studied the interplay between Ag decoration of a stepped Pt(355) surface and CO adsorption by in situ high-resolution x-ray photoelectron spectroscopy. Varying amounts of Ag deposited at 300 K initially lead to a row-by-row growth starting from the lower Pt step edges. Such decoration of the step sites results in a change in the CO adsorption behavior. An apparent blocking of step sites for low CO coverages is attributed to a change in the electronic structure, resulting in a C 1s binding energy of CO at step sites being equal to that for CO at terrace on-top sites in the presence of Ag. Higher CO coverages induce the formation of embedded Ag clusters within the upper terraces, thus freeing up a part of the original Pt step sites for CO adsorption, as was derived by a comparison to density functional theory calculations in the corresponding surface models.

Non-Abelian optical lattices: anomalous quantum Hall effect and Dirac fermions.

We study the properties of an ultracold Fermi gas loaded in an optical square lattice and subjected to an external and classical non-Abelian gauge field. We show that this system can be exploited as an optical analogue of relativistic quantum electrodynamics, offering a remarkable route to access the exotic properties of massless Dirac fermions with cold atoms experiments. In particular, we show that the underlying Minkowski space-time can also be modified, reaching anisotropic regimes where a remarkable anomalous quantum Hall effect and a squeezed Landau vacuum could be observed.

Meticillin-resistant Staphylococcus aureus contamination of healthcare workers' uniforms in long-term care facilities.

Meticillin-resistant Staphylococcus aureus (MRSA) and other multiply resistant bacteria are frequently isolated in long-term care facilities (LTCFs). This study evaluated the contamination of staff clothing in three LTCFs. Over 500 samples were taken from uniforms and their pockets and these samples showed a high level of MRSA contamination. Wearing plastic aprons and managing pocket contents improved the contamination rate. Our results highlight the continued importance of hand hygiene, since staff have frequent contact with their uniforms and could potentially contaminate their hands before care.

[Immunoassay rapid test for influenza diagnosis in institutions for elderly people: a four-year surveillance with the GROG Géronto-Alsace]. / Tests rapides de surveillance (TRS) de la grippe en établissements accueillant des personnes âgées: évaluation de quatre années d'utilisation dans le cadre du réseau GROG Géronto-Alsace.

OBJECTIVE: Outbreaks of acute respiratory infections (ARI) are common in institutions for elderly people. The objective of our study was the assessment of immunoassay rapid test used for influenza diagnosis in institutions for elderly people. METHODOLOGY: Prospective surveillance for ARI was conducted in 11 institutions in Alsace over a four-year period. Clinical case definitions are used to identify the infected residents. For the identification of influenza virus, nasopharyngeal swabs are obtained and rapid tests (immunoassay) are performed. RESULTS: Influenza virus was identified with immunoassay rapid test. Then, prophylaxis according to the Conseil supérieur d'hygiène publique de France guidelines was implemented. Nevertheless, the use of the rapid test was not frequent in the individual institution and the information recorded at the GROG Géronto-Alsace level could be use to inform the institutions when it is important to perform these rapid tests. CONCLUSION: Ours findings show the value of the rapid test used in the influenza surveillance and how the networks could help to improve their uses.

Heat conduction and Fourier's law by consecutive local mixing and thermalization.

We present a first-principles study of heat conduction in a class of models which exhibit a new multistep local thermalization mechanism which gives rise to Fourier's law. Local thermalization in our models occurs as the result of binary collisions among locally confined gas particles. We explore the conditions under which relaxation to local equilibrium, which involves no energy exchange, takes place on time scales shorter than that of the binary collisions which induce local thermalization. The role of this mechanism in multiphase material systems such as aerogels is discussed.

[Respiratory tract infections in institutions for elderly people: the GROG Géronto-Alsace, strategy of surveillance and alert]. / Infections respiratoires aiguës dans les collectivités de personnes âgées: le GROG Géronto-Alsace, une démarche expérimentale de surveillance et d'alerte.

OBJECTIVE: Outbreaks of respiratory tract infections are common in institutions for elderly people. The objective of our study was the implementation of a network including 11 institutions to determine the frequency of such outbreaks. Using the collected data, criteria and alert levels are defined to assess the level of respiratory tract infections and develop appropriate interventions. METHODOLOGY: Prospective surveillance for respiratory tract infection was conducted in 11 institutions in Alsace for 2 years. Clinical definitions were used to identify the infected residents. For the identification of influenza virus, nasopharyngeal samples using swabs were obtained and rapid tests (immunoassay) were performed. RESULTS: During the surveillance, outbreaks were identified in institutions. The same observations occurred in all institutions at the same time. Alert levels were defined in order to characterize the outbreak period and to improve detection and control of outbreaks of respiratory tract infections. CONCLUSION: Ours findings show the importance of an adequate surveillance and networks improve the impact of such measures.

The stochastic chemomechanics of the F(1)-ATPase molecular motor.

We report a theoretical study of the F(1)-ATPase molecular rotary motor experimentally studied by R. Yasuda, H. Noji, M. Yoshida, K. Kinosita Jr., H. Itoh [Nature 410 (2001) 898]. The motor is modeled as a stochastic process for the angle of its shaft and the chemical state of its catalytic sites. The stochastic process is ruled by six coupled Fokker-Planck equations for the biased diffusion of the angle and the random jumps between the chemical states. The model reproduces the experimental observations that the motor proceeds by substeps and the rotation rate saturates at high concentrations of adenosine triphosphate or at low values of the friction coefficient. Moreover, predictions are made about the dependence of the rotation rate on temperature, and about the behavior of the F(1) motor under the effect of an external torque, especially, in the regime of synthesis of adenosine triphosphate.

Transport and Helfand moments in the Lennard-Jones fluid. I. Shear viscosity.

The authors propose a new method, the Helfand-moment method, to compute the shear viscosity by equilibrium molecular dynamics in periodic systems. In this method, the shear viscosity is written as an Einstein-type relation in terms of the variance of the so-called Helfand moment. This quantity is modified in order to satisfy systems with periodic boundary conditions usually considered in molecular dynamics. They calculate the shear viscosity in the Lennard-Jones fluid near the triple point thanks to this new technique. They show that the results of the Helfand-moment method are in excellent agreement with the results of the standard Green-Kubo method.

Transport and Helfand moments in the Lennard-Jones fluid. II. Thermal conductivity.

The thermal conductivity is calculated with the Helfand-moment method in the Lennard-Jones fluid near the triple point. The Helfand moment of thermal conductivity is here derived for molecular dynamics with periodic boundary conditions. Thermal conductivity is given by a generalized Einstein relation with this Helfand moment. The authors compute thermal conductivity by this new method and compare it with their own values obtained by the standard Green-Kubo method. The agreement is excellent.