930 research outputs found
Definition and relevance of nonequilibrium intensive thermodynamic parameters
We show that intensive thermodynamic parameters associated to additive
conserved quantities can be naturally defined from a statistical approach in
far-from-equilibrium steady-state systems, under few assumptions, and without
any detailed balance requirement. It may apply, e.g., to dissipative systems
like granular gases where volume or mass is still conserved, or to systems with
periodic boundary conditions where fluxes of conserved quantities are present.
We emphasize the usefulness of this concept to characterize the coexistence of
different nonequilibrium phases, and discuss the influence of the contact
between two different systems, in relation with measurement issues.Comment: 4 pages, final versio
Can the post-Newtonian gravitational waveform of an inspiraling binary be improved by solving the energy balance equation numerically?
The detection of gravitational waves from inspiraling compact binaries using
matched filtering depends crucially on the availability of accurate template
waveforms. We determine whether the accuracy of the templates' phasing can be
improved by solving the post-Newtonian energy balance equation numerically,
rather than (as is normally done) analytically within the post-Newtonian
perturbative expansion. By specializing to the limit of a small mass ratio, we
find evidence that there is no gain in accuracy.Comment: 13 pages, RevTeX, 5 figures included via eps
Entropy-based characterizations of the observable-dependence of the fluctuation-dissipation temperature
The definition of a nonequilibrium temperature through generalized
fluctuation-dissipation relations relies on the independence of the
fluctuation-dissipation temperature from the observable considered. We argue
that this observable independence is deeply related to the uniformity of the
phase-space probability distribution on the hypersurfaces of constant energy.
This property is shown explicitly on three different stochastic models, where
observable-dependence of the fluctuation-dissipation temperature arises only
when the uniformity of the phase-space distribution is broken. The first model
is an energy transport model on a ring, with biased local transfer rules. In
the second model, defined on a fully connected geometry, energy is exchanged
with two heat baths at different temperatures, breaking the uniformity of the
phase-space distribution. Finally, in the last model, the system is connected
to a zero temperature reservoir, and preserves the uniformity of the
phase-space distribution in the relaxation regime, leading to an
observable-independent temperature.Comment: 15 pages, 7 figure
Recommended from our members
Bacterial pathogens and resistance causing community acquired paediatric bloodstream infections in low- and middle-income countries: a systematic review and meta-analysis
Background
Despite a high mortality rate in childhood, there is limited evidence on the causes and outcomes of paediatric bloodstream infections from low- and middle-income countries (LMICs). We conducted a systematic review and meta-analysis to characterize the bacterial causes of paediatric bloodstream infections in LMICs and their resistance profile.
Methods
We searched Pubmed and Embase databases between January 1st 1990 and October 30th 2019, combining MeSH and free-text terms for “sepsis” and “low-middle-income countries” in children. Two reviewers screened articles and performed data extraction to identify studies investigating children (1 month-18 years), with at least one blood culture. The main outcomes of interests were the rate of positive blood cultures, the distribution of bacterial pathogens, the resistance patterns and the case-fatality rate. The proportions obtained from each study were pooled using the Freeman-Tukey double arcsine transformation, and a random-effect meta-analysis model was used.
Results
We identified 2403 eligible studies, 17 were included in the final review including 52,915 children (11 in Africa and 6 in Asia). The overall percentage of positive blood culture was 19.1% [95% CI: 12.0–27.5%]; 15.5% [8.4–24.4%] in Africa and 28.0% [13.2–45.8%] in Asia. A total of 4836 bacterial isolates were included in the studies; 2974 were Gram-negative (63.9% [52.2–74.9]) and 1858 were Gram-positive (35.8% [24.9–47.5]). In Asia, Salmonella typhi (26.2%) was the most commonly isolated pathogen, followed by Staphylococcus aureus (7.7%) whereas in Africa, S. aureus (17.8%) and Streptococcus pneumoniae (16.8%) were predominant followed by Escherichia coli (10.7%). S. aureus was more likely resistant to methicillin in Africa (29.5% vs. 7.9%), whereas E. coli was more frequently resistant to third-generation cephalosporins (31.2% vs. 21.2%), amikacin (29.6% vs. 0%) and ciprofloxacin (36.7% vs. 0%) in Asia. The overall estimate for case-fatality rate among 8 studies was 12.7% [6.6–20.2%]. Underlying conditions, such as malnutrition or HIV infection were assessed as a factor associated with bacteraemia in 4 studies each.
Conclusions
We observed a marked variation in pathogen distribution and their resistance profiles between Asia and Africa. Very limited data is available on underlying risk factors for bacteraemia, patterns of treatment of multidrug-resistant infections and predictors of adverse outcomes
Non-equilibrium temperatures in steady-state systems with conserved energy
We study a class of non-equilibrium lattice models describing local
redistributions of a globally conserved quantity, which is interpreted as an
energy. A particular subclass can be solved exactly, allowing to define a
statistical temperature T_{th} along the same lines as in the equilibrium
microcanonical ensemble. We compute the response function and find that when
the fluctuation-dissipation relation is linear, the slope T_{FD}^{-1} of this
relation differs from the inverse temperature T_{th}^{-1}. We argue that T_{th}
is physically more relevant than T_{FD}, since in the steady-state regime, it
takes equal values in two subsystems of a large isolated system. Finally, a
numerical renormalization group procedure suggests that all models within the
class behave similarly at a coarse-grained level, leading to a new parameter
which describes the deviation from equilibrium. Quantitative predictions
concerning this parameter are obtained within a mean-field framework.Comment: 16 pages, 2 figures, submitted to Phys. Rev.
Dysphagia in Elderly Women: Consider Tetanus
Background:: Dysphagia is seldom caused by tetanus; however, it is a common symptom of tetanus. Treating patients with tetanus is a rare event in industrialized countries and awareness is needed to recognize early signs of this serious disease. In Switzerland, the most recently reported tetanus cases occurred in elderly women with insufficient seroprotection. Patients:: We report on three elderly women presenting with dysphagia as an initial symptom of tetanus. Results:: Generalized tetanus was diagnosed in two patients upon admission, the third presented with cephalic tetanus with secondary generalization. All three patients had undetectable levels of tetanus antibodies and had no documented prior tetanus immunizations. Cultures of wound swabs grew Clostridium tetani in all cases. Electromyography was highly suggestive for tetanus in two patients. Treatment involved mechanical ventilation, intravenous benzodiazepine and metronidazole therapy, and active and passive tetanus immunization. The disease had a favorable outcome in two cases and was fatal in one. Conclusion:: Tetanus remains a threat in patients with insufficient seroprotection and efforts are needed to improve tetanus immunization in these individuals. Tetanus should be considered in the differential diagnosis of dysphagi
Effects of bioaerosol exposure on work-related symptoms among Swiss sawmill workers
Objective: Exposure to bioaerosols in the occupational environment of sawmills could be associated with a wide range of health effects, in particular respiratory impairment, allergy and organic dust toxic syndrome. The objective of the study was to assess the frequency of medical respiratory and general symptoms and their relation to bioaerosol exposure. Method: Twelve sawmills in the French part of Switzerland were investigated and the relationship between levels of bioaerosols (wood dust, airborne bacteria, airborne fungi and endotoxins), medical symptoms and impaired lung function was explored. A health questionnaire was distributed to 111 sawmill workers. Results: The concentration of airborne fungi exceeded the limit recommended by the Swiss National Insurance (SUVA) in the twelve sawmills. This elevated fungi level significantly influenced the occurrence of bronchial syndrome (defined by cough and expectorations). No other health effects (irritations or respiratory effects) could be associated to the measured exposures. We observed that junior workers showed significantly more irritation syndrome (defined by itching/running nose, snoring and itching/red eyes) than senior workers. Lung function tests were not influenced by bioaerosol levels nor dust exposure levels. Conclusion: Results suggest that occupational exposure to wood dust in a Swiss sawmill does not promote a clinically relevant decline in lung function. However, the occurrence of bronchial syndrome is strongly influenced by airborne fungi level
Horizons Inside Classical Lumps
Hopefully tex-able version.Comment: 13 pages, UMHEP-37
Temperature in nonequilibrium systems with conserved energy
We study a class of nonequilibrium lattice models which describe local
redistributions of a globally conserved energy. A particular subclass can be
solved analytically, allowing to define a temperature T_{th} along the same
lines as in the equilibrium microcanonical ensemble. The
fluctuation-dissipation relation is explicitely found to be linear, but its
slope differs from the inverse temperature T_{th}^{-1}. A numerical
renormalization group procedure suggests that, at a coarse-grained level, all
models behave similarly, leading to a two-parameter description of their
macroscopic properties.Comment: 4 pages, 1 figure, final versio
- …