3,053 research outputs found
Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b
The nearby extrasolar planet GJ 436b--which has been labelled as a 'hot
Neptune'--reveals itself by the dimming of light as it crosses in front of and
behind its parent star as seen from Earth. Respectively known as the primary
transit and secondary eclipse, the former constrains the planet's radius and
mass, and the latter constrains the planet's temperature and, with measurements
at multiple wavelengths, its atmospheric composition. Previous work using
transmission spectroscopy failed to detect the 1.4-\mu m water vapour band,
leaving the planet's atmospheric composition poorly constrained. Here we report
the detection of planetary thermal emission from the dayside of GJ 436b at
multiple infrared wavelengths during the secondary eclipse. The best-fit
compositional models contain a high CO abundance and a substantial methane
(CH4) deficiency relative to thermochemical equilibrium models for the
predicted hydrogen-dominated atmosphere. Moreover, we report the presence of
some H2O and traces of CO2. Because CH4 is expected to be the dominant
carbon-bearing species, disequilibrium processes such as vertical mixing and
polymerization of methane into substances such as ethylene may be required to
explain the hot Neptune's small CH4-to-CO ratio, which is at least 10^5 times
smaller than predicted
The problematic backreaction of SUSY-breaking branes
In this paper we investigate the localisation of SUSY-breaking branes which,
in the smeared approximation, support specific non-BPS vacua. We show, for a
wide class of boundary conditions, that there is no flux vacuum when the branes
are described by a genuine delta-function. Even more, we find that the smeared
solution is the unique solution with a regular brane profile. Our setup
consists of a non-BPS AdS_7 solution in massive IIA supergravity with smeared
anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.Comment: 27 pages, Latex2e, 5 figure
PONTAS ABRASIVAS PARA REMOÇÃO DE MANCHAS E FECHAMENTO DE DIASTEMA COM RC RELATO DE CASO CLÍNICO
Com o passar dos anos a estética vem ganhando uma maior atenção na odontologia e através das resinas compostas, o cirurgião dentista, procura conciliar a estética a um preparo menos invasivo o qual necessita de acabamento e polimento, essencial para não haver rugosidade superficial, porosidade, ausência de brilho e alteração de cor. Resinas compostas são melhores materiais e lixas abrasivas têm técnicas de acabamento e polimento adequadas para que o profissional possa oferecer restaurações com alta qualidade e com maior durabilidade para satisfação do paciente
Synthesis of titanate nanostructures using amorphous precursor material and their adsorption/photocatalytic properties
This paper reports on a new and swift hydrothermal chemical route to prepare
titanate nanostructures (TNS) avoiding the use of crystalline TiO2 as starting
material. The synthesis approach uses a commercial solution of TiCl3 as
titanium source to prepare an amorphous precursor, circumventing the use of
hazardous chemical compounds. The influence of the reaction temperature and
dwell autoclave time on the structure and morphology of the synthesised
materials was studied. Homogeneous titanate nanotubes with a high
length/diameter aspect ratio were synthesised at 160^{\circ}C and 24 h. A band
gap of 3.06\pm0.03 eV was determined for the TNS samples prepared in these
experimental conditions. This value is red shifted by 0.14 eV compared to the
band gap value usually reported for the TiO2 anatase. Moreover, such samples
show better adsorption capacity and photocatalytic performance on the dye
rhodamine 6G (R6G) photodegradation process than TiO2 nanoparticles. A 98%
reduction of the R6G concentration was achieved after 45 minutes of irradiation
of a 10 ppm dye aqueous solution and 1 g/L of TNS catalyst.Comment: 29 pages, 10 figures, accepted for publication in Journal of
Materials Scienc
Efficacious, effective, and embedded interventions: Implementation research in infectious disease control
Background: Research in infectious disease control is heavily skewed towards high end
technology; development of new drugs, vaccines and clinical interventions. Oft ignored, is the
evidence to inform the best strategies that ensure the embedding of interventions into health
systems and amongst populations. In this paper we undertake an analysis of the challenge in the
development of research for the sustainable implementation of disease control interventions.
Results: We highlight the fundamental differences between the research paradigms associated
with the development of technologies and interventions for disease control on the one hand and the research paradigms required for enhancing the sustainable uptake of those very same
interventions within the communities on the other. We provide a definition for implementation
research in an attempt to underscore its critical role and explore the multidisciplinary science
needed to address the challenges in disease control.
Conclusion: The greatest value for money in health research lies in the sustainable and effective implementation of already proven, efficacious solutions. The development of implementation research that can help provide some solutions on how this can be achieved is sorely needed
Derrame pleuropericárdico: no todo es lupus
A 69-year-old woman was admitted in our hospital with dyspnoea in context of heart failure. She was diagnosed of autoimmune hemolityc anemia, treated with steroids. Echocardiography revealed a severe pleuropericardial effusion. A pericardiocentesis and thoracocentesis were performed and other test was performed due to obtain a diagnosis. The patient was diagnosed of primary effusion lymphoma associated to Epstein-Barr infection. Primary effusion lymphoma is an uncommon type of lymphoma found mainly in immunosuppressed patients positive HIV and human herpesvirus 8 infection with unfavourable prognosis. After chemotherapy treatment with R-CHOP cycles, the patient is now in remission.Mujer de 69 años que presenta cuadro clínico de disnea en el contexto de insuficiencia cardíaca aguda y tratamiento crónico con corticoides por anemia hemolítica autoinmune. En las pruebas complementarias se observa derrame pleuropericárdico severo. Ante estos hallazgos se realiza pericardiocentesis y toracocentesis y se completa estudio para descartar patología tumoral, infecciosa, tiroidea y autoinmune. Se diagnostica a la paciente de linfoma primario de cavidades, asociado a infección por virus de Epstein-Barr. Es un tipo poco frecuente de linfoma que se describe fundamentalmente en pacientes infectados por virus de la inmunodeficiencia humana y asociados al virus herpes humano tipo 8 con pronóstico muy desfavorable. Tras tratamiento quimioterápico con ciclos de R-CHOP la paciente se encuentra actualmente en remisión completa
Quality of life in the Iranian Blind War Survivors in 2007: a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Quality of Life measurements are necessary tools for effectively evaluating health services. In the population of patients afflicted with war-related blindness in Iran, such measurements have yet to be documented and utilized. "The design and implementation of this study involved the determination of a baseline score for QOL in a population of Iranian blinded in the Iraq-Iran war in order to facilitate the design of interventions intended to improve the population's QOL."</p> <p>Methods</p> <p>This was a cross-sectional study of a representative population of 250 war victims blind in both eyes at a 14-day recreational conference.</p> <p>Results</p> <p>Participants had a mean age of 43.20(SD8.34) and their composition was 96.5% male and 3.5% female with a mean SF-36 QOL score of 59.20(SD22.80). An increasing level of education among the participants correlated with a higher QOL score (p = 0.006). The QOL also has a significant correlation to number of injuries (p < 0.0001). High systolic and diastolic blood pressure, hearing loss, and tinnitus had negative individual correlations to QOL (p = 0.016, 0.016, 0.005, p < 0.0001). The male sexual disorders of erectile dysfunction and premature ejaculation both had significant correlations to QOL (p = 0.026, p < 0.0001). Hypercholesterolemia showed significant correlation to QOL (p = 0.021).</p> <p>Conclusions</p> <p>As blind war survivors' age, they will present with a greater set of burdens despite their relatively better QOL in the physical component scale when compared with lower limb amputees. Risk factors of cardiovascular attack such as high blood pressure and hypercholesterolemia were present and need future interventions.</p> <p>Key words</p> <p>Quality of life, blindness, SF36, health</p
The utilization of antidepressants and benzodiazepines among people with major depression in Canada
Objective: Although clinical guidelines recommend monotherapy with antidepressants (ADs) for major depression, polypharmacy with benzodiazepines (BDZs) remains an issue. Risks associated with such treatments include tolerance and dependence, among others. We assessed the prevalence and determinants of AD and BDZ utilization among Canadians who experienced a major depressive episode (MDE) in the previous 12 months, and determined the association of seeing a psychiatrist on the utilization of ADs and BDZs. Method: Data were drawn from the 2002 Canadian Community Health Survey: Health and Well-Being, a nationally representative sample of Canadians aged 15 years and older. Descriptive statistics quantified utilization, while logistic regression identified factors associated with utilization, such as sociodemographic characteristics or type of physician seen. Sampling weights and bootstrap variance estimations were used for all analysis. Results: The overall prevalence of AD and BDZ utilization was 49.3% of respondents who experienced an MDE in the past 12 months and reported AD use. Key determinants of utilization were younger age and unemployment in the past week (OR 2.6; P < 0.001). Being seen by a psychiatrist increased utilization (OR 2.5; P < 0.001), possibly because psychiatrists were seeing patients with severe depression. Conclusion: A large proportion of people with past-year MDEs utilized ADs and BDZs. It is unclear how much of this is appropriate given that evidence-based clinical guidelines recommend monotherapy with ADs in the treatment of major depression
Environmental risk assessment of genetically modified plants - concepts and controversies
Background and purpose: In Europe, the EU Directive 2001/18/EC lays out the main provisions of environmental risk assessment (ERA) of genetically modified (GM) organisms that are interpreted very differently by different stakeholders. The purpose of this paper is to: (a) describe the current implementation of ERA of GM plants in the EU and its scientific shortcomings, (b) present an improved ERA concept through the integration of a previously developed selection procedure for identification of non-target testing organisms into the ERA framework as laid out in the EU Directive 2001/18/EC and its supplement material (Commission Decision 2002/623/EC), (c) describe the activities to be carried out in each component of the ERA and (d) propose a hierarchical testing scheme. Lastly, we illustrate the outcomes for three different crop case examples.
Main features: Implementation of the current ERA concept of GM crops in the EU is based on an interpretation of the EU regulations that focuses almost exclusively on the isolated bacteria-produced novel proteins with little consideration of the whole plant. Therefore, testing procedures for the effect assessment of GM plants on non-target organisms largely follow the ecotoxicological testing strategy developed for pesticides. This presumes that any potential adverse effect of the whole GM plant and the plant-produced novel compound can be extrapolated from testing of the isolated bacteriaproduced novel compound or can be detected in agronomic field trials. This has led to persisting scientific criticism.
Results: Based on the EU ERA framework, we present an improved ERA concept that is system oriented with the GM plant at the centre and integrates a procedure for selection of testing organisms that do occur in the receiving environment. We also propose a hierarchical testing scheme from laboratory studies to field trials and we illustrate the outcomes for three different crop case examples.
Conclusions and recommendations: Our proposed concept can alleviate a number of deficits identified in the current approach to ERA of GM plants. It allows the ERA to be tailored to the GM plant case and the receiving environment
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