202 research outputs found
Magnetothermodynamics of BPS baby skyrmions
The magnetothermodynamics of skyrmion type matter described by the gauged BPS
baby Skyrme model at zero temperature is investigated. We prove that the BPS
property of the model is preserved also for boundary conditions corresponding
to an asymptotically constant magnetic field. The BPS bound and the
corresponding BPS equations saturating the bound are found. Further, we show
that one may introduce pressure in the gauged model by a redefinition of the
superpotential. Interestingly, this is related to non-extremal type solutions
in the so-called fake supersymmetry method. Finally, we compute the equation of
state of magnetized BSP baby skyrmions inserted into an external constant
magnetic field and under external pressure , i.e., , where
is the "volume" (area) occupied by the skyrmions. We show that the BPS baby
skyrmions form a ferromagnetic medium.Comment: Latex, 39 pages, 14 figures. v2: New results and references added,
physical interpretation partly change
Impact of Diabetes on Work Cessation: Data from the GAZEL cohort study
International audienceOBJECTIVE: To measure the impact of diabetes on work cessation, i.e., on the risks of work disability, early retirement, and death while in the labor force. RESEARCH DESIGN AND METHODS: We used data from the GAZEL prospective cohort of 20,625 employees of the French national gas and electricity company "EDF-GDF." We identified 506 employees with diabetes and randomly selected 2,530 nondiabetic employed control subjects matched for major sociodemographic and occupational characteristics. Using a multistate Cox model, we estimated hazard ratios (HRs) comparing the risks of transition from employment to disability, retirement, and death over time between participants with versus without diabetes. RESULTS: Employment rate decreased more rapidly in participants with diabetes (51.9 and 10.1% at 55 and 60 years, respectively) compared with nondiabetic participants (66.5 and 13.4%, respectively). Participants with diabetes had significantly increased risks of transition from employment to disability (HR 1.7 [95% CI 1.0-2.9]), retirement (HR 1.6 [1.5-1.8]), and death (HR 7.3 [3.6-14.6]) compared with participants without diabetes. Between 35 and 60 years, each participant with diabetes lost an estimated mean time of 1.1 year in the workforce (95% CI 0.99-1.14) compared with a nondiabetic participant. CONCLUSIONS: Our results provide evidence for a profound negative impact of diabetes on workforce participation in France. Social and economic consequences are major for patients, employers, and society-a burden that is likely to increase as diabetes becomes more and more common in the working-aged population
Vaccines against toxoplasma gondii : challenges and opportunities
Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge
Performance of polyethyleneimineâsilica adsorbent for post-combustion CO2 capture in a bubbling fluidized bed
The high performance of polyethyleneimine (PEI)-based solid adsorbent for CO2 capture has been well recognized in thermogravimetric analysis (TGA) and small-scale fixed bed reactors through the measurements of their equilibrium capacities but has not been really demonstrated on larger scales towards practical utilization. In the present study, a laboratory-scale bubbling fluidized bed reactor loaded with a few kg adsorbent is used to evaluate the adsorption performance of PEIâsilica adsorbent under different working conditions including with/without the presence of moisture, different gasâsolid contact times, initial bed temperatures, and CO2 partial pressures. The adsorption capacities have shown a clear degradation tendency under dry condition. However, they can be stabilized at a high level of 10.6â11.1% w/w over 60 cycles if moisture (ca. 8.8 vol%) is present in the gas flow during adsorption and desorption. Breakthrough capacities can be stabilized at the level of 7.6â8.2% w/w with the gasâsolid contact time of 13 s. The adsorption capacities for the simulated flue gases containing 5% CO2 are only slightly lower than those for the simulated flue gases containing 15% CO2, indicating that the PEIâsilica adsorbent is suitable for CO2 capture from flue gases of both coal-fired and natural gas-fired combined cycle power plants. The exothermal heat of adsorption is estimated by the energy balance in the fluidized bed reactor and found to be close (within 10%) to the measured value by TG-DSC. The regeneration heat for the as prepared PEIâsilica adsorbent is found to be 2360 kJ/kgCO2 assuming 75% recovery of sensible heat which is well below the values of 3900â4500 kJ/kgCO2 for a typical MEA scrubbing process with 90% recovery of sensible heat
Temporal correlations among demographic parameters are ubiquitous but highly variable across species
Temporal correlations among demographic parameters can strongly influence
population dynamics. Our empirical knowledge, however, is very limited regarding
the direction and the magnitude of these correlations and how they vary among
demographic parameters and speciesâ life histories. Here, we use long-term
demographic data from 15 bird and mammal species with contrasting pace of life
to quantify correlation patterns among five key demographic parameters: juvenile and adult survival, reproductive probability, reproductive success and productivity.
Correlations among demographic parameters were ubiquitous, more frequently
positive than negative, but strongly differed across species. Correlations did not
markedly change along the slow-fast continuum of life histories, suggesting that
they were more strongly driven by ecological than evolutionary factors. As positive
temporal demographic correlations decrease the mean of the long-run population
growth rate, the common practice of ignoring temporal correlations in population
models could lead to the underestimation of extinction risks in most species
The CONSTANCES cohort: an open epidemiological laboratory
<p>Abstract</p> <p>Background</p> <p>Prospective cohorts represent an essential design for epidemiological studies and allow for the study of the combined effects of lifestyle, environment, genetic predisposition, and other risk factors on a large variety of disease endpoints. The CONSTANCES cohort is intended to provide public health information and to serve as an "open epidemiologic laboratory" accessible to the epidemiologic research community. Although designed as a "general-purpose" cohort with very broad coverage, it will particularly focus on occupational and social determinants of health, and on aging.</p> <p>Methods/Design</p> <p>The CONSTANCES cohort is designed as a randomly selected representative sample of French adults aged 18-69 years at inception; 200,000 subjects will be included over a five-year period. At inclusion, the selected subjects will be invited to fill a questionnaire and to attend a Health Screening Center (HSC) for a comprehensive health examination: weight, height, blood pressure, electrocardiogram, vision, auditory, spirometry, and biological parameters; for those aged 45 years and older, a specific work-up of functional, physical, and cognitive capacities will be performed. A biobank will be set up. The follow-up includes a yearly self-administered questionnaire, and a periodic visit to an HSC. Social and work-related events and health data will be collected from the French national retirement, health and death databases. The data that will be collected include social and demographic characteristics, socioeconomic status, life events, behaviors, and occupational factors. The health data will cover a wide spectrum: self-reported health scales, reported prevalent and incident diseases, long-term chronic diseases and hospitalizations, sick-leaves, handicaps, limitations, disabilities and injuries, healthcare utilization and services provided, and causes of death.</p> <p>To take into account non-participation at inclusion and attrition throughout the longitudinal follow-up, a cohort of non-participants will be set up and followed through the same national databases as participants.</p> <p>A field-pilot was performed in 2010 in seven HSCs, which included about 3,500 subjects; it showed a satisfactory structure of the sample and a good validity of the collected data.</p> <p>Discussion</p> <p>The constitution of the full eligible sample is planned during the last trimester of 2010, and the cohort will be launched at the beginning of 2011.</p
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