1,319 research outputs found
Cosmological particle production, causal thermodynamics, and inflationary expansion
Combining the equivalence between cosmological particle creation and an
effective viscous fluid pressure with the fact that the latter represents a
dynamical degree of freedom within the second-order Israel-Stewart theory for
imperfect fluids, we reconsider the possibility of accelerated expansion in
fluid cosmology. We find an inherent self-limitation for the magnitude of an
effective bulk pressure which is due to adiabatic (isentropic) particle
production. For a production rate which depends quadratically on the Hubble
rate we confirm the existence of solutions which describe a smooth transition
from inflationary to noninflationary behavior and discuss their interpretation
within the model of a decaying vacuum energy density. An alternative
formulation of the effective imperfect fluid dynamics in terms of a minimally
coupled scalar field is given. The corresponding potential is discussed and an
entropy equivalent for the scalar field is found.Comment: 16 pages, revtex file, submitted to Phys. Rev.
Impacts of climate and land use changes on the hydrological and erosion processes of two contrasting Mediterranean catchments
The impacts of climate and land use changes on streamflow and sediment export were evaluated for a humid (São Lourenço) and a dry (Guadalupe) Mediterranean catchment, using the SWAT model. SWAT was able to produce viable streamflow and sediment export simulations for both catchments, which provided a baseline for investigating climate and land use changes under the A1B and B1 emission scenarios for 2071–2100. Compared to the baseline scenario (1971–2000), climate change scenarios showed a decrease in annual rainfall for both catchments (humid: − 12%; dry: − 8%), together with strong increases in rainfall during winter. Land use changes were derived from a socio-economic storyline in which traditional agriculture is replaced by more profitable land uses (i.e. corn and commercial forestry at the humid site; sunflower at the dry site). Climate change projections showed a decrease in streamflow for both catchments, whereas sediment export decreased only for the São Lourenço catchment. Land use changes resulted in an increase in streamflow, but the erosive response differed between catchments. The combination of climate and land use change scenarios led to a reduction in streamflow for both catchments, suggesting a domain of the climatic response. As for sediments, contrasting results were observed for the humid (A1B: − 29%; B1: − 22%) and dry catchment (A1B: + 222%; B1: + 5%), which is mainly due to differences in the present-day and forecasted vegetation types. The results highlight the importance of climate-induced land-use change impacts, which could be similar to or more severe than the direct impacts of climate change alone
Antibacterial E ect of Chitosan–Gold Nanoparticles and Computational Modeling of the Interaction between Chitosan and a Lipid Bilayer Model
Pathogenic bacteria have the ability to develop antibiotic resistance mechanisms. Their action consists mainly in the production of bacterial enzymes that inactivate antibiotics or the appearance of modifications that prevent the arrival of the drug at the target point or the alteration of the target point itself, becoming a growing problem for health systems. Chitosan–gold nanoparticles (Cs-AuNPs) have been shown as effective bactericidal materials avoiding damage to human cells. In this work, Cs-AuNPs were synthesized using chitosan as the reducing agent, and a systematic analysis of the influence of the synthesis parameters on the size and zeta potential of the Cs-AuNPs and their UV-vis spectra was carried out. We used a simulation model to characterize the interaction of chitosan with bacterial membranes, using a symmetric charged bilayer and two different chitosan models with different degrees of the chitosan amine protonation as a function of pH, with the aim to elucidate the antibacterial mechanism involving the cell wall disruption. The Cs-AuNP antibacterial activity was evaluated to check the simulation model
Specific heat and magnetic measurements in Nd0.5Sr0.5MnO3, Nd0.5Ca0.5MnO3 and Ho0.5Ca0.5MnO3 samples
We studied the magnetization as a function of temperature and magnetic field
in the compounds Nd0.5Sr0.5MnO3, Nd0.5Ca0.5MnO3 and Ho0.5Ca0.5MnO3. It allowed
us to identify the ferromagnetic, antiferromagnetic and charge ordering phases
in each case. The intrinsic magnetic moments of Nd3+ and Ho3+ ions experienced
a short range order at low temperatures. We also did specific heat measurements
with applied magnetic fields between 0 and 9 T and temperatures between 2 and
300 K in all three samples. Close to the charge ordering and ferromagnetic
transition temperatures the specific heat curves showed peaks superposed to the
characteristic response of the lattice oscillations. Below 10 K the specific
heat measurements evidenced a Schottky-like anomaly for all samples. However,
we could not successfully fit the curves to either a two level nor a
distribution of two-level Schottky anomaly. Our results indicated that the peak
temperature of the Schottky anomaly was higher in the compounds with narrower
conduction band.Comment: submitted to PR
Antibacterial Effect of Chitosan–Gold Nanoparticles and Computational Modeling of the Interaction between Chitosan and a Lipid Bilayer Model
Pathogenic bacteria have the ability to develop antibiotic resistance mechanisms. Their action consists mainly in the production of bacterial enzymes that inactivate antibiotics or the appearance of modifications that prevent the arrival of the drug at the target point or the alteration of the target point itself, becoming a growing problem for health systems. Chitosan–gold nanoparticles (Cs-AuNPs) have been shown as effective bactericidal materials avoiding damage to human cells. In this work, Cs-AuNPs were synthesized using chitosan as the reducing agent, and a systematic analysis of the influence of the synthesis parameters on the size and zeta potential of the Cs-AuNPs and their UV-vis spectra was carried out. We used a simulation model to characterize the interaction of chitosan with bacterial membranes, using a symmetric charged bilayer and two different chitosan models with different degrees of the chitosan amine protonation as a function of pH, with the aim to elucidate the antibacterial mechanism involving the cell wall disruption. The Cs-AuNP antibacterial activity was evaluated to check the simulation model.Fil: Fuster, M.G.. Universidad de Murcia. Facultad de Química; EspañaFil: Montalbán, M. G.. Universidad de Murcia. Facultad de Química; EspañaFil: Carissimi, G.. Universidad de Murcia. Facultad de Química; EspañaFil: Lima, Beatriz Viviana. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Feresin, Gabriela Egly. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Cano, M.. Universidad de Cordoba. Instituto Universitario de Investigación En Química Fina y Nanoquímica.; EspañaFil: Giner Casares, J. J.. Universidad de Cordoba. Instituto Universitario de Investigación En Química Fina y Nanoquímica.; EspañaFil: López Cascales, J.J.. Universidad Politécnica de Cartagena; EspañaFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Víllora, G.. Universidad de Murcia. Facultad de Química; Españ
Trends analysis of specialized palliative care services in 51 countries of the WHO European region in the last 14 years
Background: Service provision is a key domain to assess national-level palliative care development. Three editions of the European Association for Palliative Care (EAPC) Atlas of Palliative Care monitored the changes in service provision across Europe since 2005. Aim: To study European trends of specialized service provision at home care teams, hospital support teams, and inpatient palliative care services between 2005 and 2019. Design: Secondary analysis was conducted drawing from databases on the number of specialized services in 2005, 2012, and 2019. Ratios of services per 100,000 inhabitants and increase rates on number of services for three periods were calculated. Analysis of variance (ANOVA) analyses were conducted to determine significant changes and chi-square to identify countries accounting for the variance. Income-level and sub-regional ANOVA analysis were undertaken. Setting: 51 countries. Results: Forty-two countries (82%) increased the number of specialized services between 2005 and 2019 with changes for home care teams (104% increase-rate), inpatient services (82%), and hospital support teams (48%). High-income countries showed significant increase in all types of services (p < 0.001), while low-to-middle-income countries showed significant increase only for inpatient services. Central–Eastern European countries showed significant improvement in home care teams and inpatient services, while Western countries showed significant improvement in hospital support and home care teams. Home care was the most prominent service in Western Europe. Conclusion: Specialized service provision increased throughout Europe, yet ratios per 100,000 inhabitants fell below the EAPC recommendations. Western Europe ratios’ achieved half of the suggested services, while Central–Eastern countries achieved only a fourth. High-income countries and Western European countries account for the major increase. Central–Eastern Europe and low-to-middle-income countries reported little increase on specialized service provision
Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors
Quasiclassic Uzadel equations for two-band superconductors in the dirty limit
with the account of both intraband and interband scattering by nonmagnetic
impurities are derived for any anisotropic Fermi surface. From these equations
the Ginzburg-Landau equations, and the critical temperature are obtained.
An equation for the upper critical field, which determines both the temperature
dependence of and the orientational dependence of
as a function of the angle between and the c-axis is
obtained. It is shown that the shape of the curve essentially
depends on the ratio of the intraband electron diffusivities and ,
and can be very different from the standard one-gap dirty limit theory. In
particular, the value can considerably exceed ,
which can have important consequences for applications of . A scaling
relation is proposed which enables one to obtain the angular dependence of
from the equation for at . It is shown
that, depending on the relation between and , the ratio of the upper
critical field for and can both increase and decrease as the temperature decreases. Implications
of the obtained results for are discussed
Atlas de Cuidados Paliativos en Latinoamérica. Edición Cartográfica 2013
El Atlas de Cuidados Paliativos en Latinoamérica es un estudio descriptivo de análisis comparativo de datos y/o estimaciones sobre el desarrollo de servicios e iniciativas de Cuidados Paliativos en Latinoamérica. El desarrollo y modelo del Atlas de Cuidados Paliativos en Latinoamérica se basó en el Atlas de Cuidados Paliativos de la Asociación Europea de Cuidados Paliativos (EAPC).
La información se obtuvo por medio de una encuesta semi-estructurada a profesionales de Cuidados Paliativos en cada país. Este instrumento fue elaborado por Tania Pastrana, Carlos Centeno y Liliana De Lima y contó con la asesoría de Isabel Torres.
El instrumento fue probado en un estudio piloto con 6 personas y de acuerdo a los resultados se hicieron los cambios necesarios.
En esta primera versión del Atlas Latinoamericano de Cuidados Paliativos fueron incluidos 19 países latinoamericanos, con lenguaje oficial español o portugué
Mapping pediatric palliative care development in the WHO-European Region: children living in low-middle income countries are less likely to access it
Context: Approximately 170,000 children in need of palliative care die every year in Europe without access to it. This field remains an evolving specialty with unexplored development. Objectives: To conduct the first regional assessment of pediatric palliative care (PPC) development and provision using data from the European Association for Palliative Care atlas of palliative care 2019. Methods: Two surveys were conducted. The first one included a single question regarding PPC service provision and was addressed by European Association for Palliative Care atlas informants. The second one included 10 specific indicators derived from an open-ended interview and rating process; a specific network of informants was enabled and used as respondents. Data were analyzed and presented in the map of the figure. Results: Data on PPC service provision were gathered from 51 of 54 (94%) European countries. Additional data were collected in 34 of 54 (62%) countries. A total of 680 PPC services were identified including 133 hospices, 385 home care services, and 162 hospital services. Nineteen countries had specific standards and norms for the provision of PPC. Twenty-two countries had a national association, and 14 countries offered education for either pediatric doctors or nurses. In seven countries, specific neonatal palliative care referral services were identified. Conclusion: PPC provision is flourishing across the region; however, development is less accentuated in low-to-middle-income countries. Efforts need to be devoted to the conceptualization and definition of the models of care used to respond to the unmet need of PPC in Europe. The question whether specialized services are required or not should be further explored. Strategies to regulate and cover patients in need should be adapted to each national health system
Epidemiology and Risk Factors for Cryptosporidiosis in Children from 8 Low-income Sites : Results from the MAL-ED Study
Funding Information: The MAL-ED study is carried out as a collaborative project supported by the Bill & Melinda Gates Foundation, the Foundation for the National Institutes of Health (NIH), and the NIH Fogarty International Center. This work was also supported by the National Institute of Allergy and Infectious Diseases of the NIH (grant numbers K23 AI087910 to P. K. and K23 AI087910 to W. A. P.) and by the Sherrilyn and Ken Fisher Center for Environmental Infectious Diseases Discovery Program (to P. D.).Peer reviewedPublisher PD
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