4,207 research outputs found

    The dynamics of apparent horizons in Robinson-Trautman spacetimes

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    We present an alternative scheme of finding apparent horizons based on spectral methods applied to Robinson-Trautman spacetimes. We have considered distinct initial data such as representing the spheroids of matter and the head-on collision of two non-rotating black holes. The evolution of the apparent horizon is presented. We have obtained in some cases a mass gap between the final Bondi and apparent horizon masses, whose implications were briefly commented in the light of the thermodynamics of black holes.Comment: 9 pages, 7 figure

    Total synthesis of the potent immunosuppressant (-)-Pironetin

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    A convergent and efficient total synthesis of (-)-pironetin, a compound that shows plant growth regulatory activity, and is immunosuppressive as well as having remarkable antitumoral activity, is described. The synthesis required 19 steps from N-propionyl oxazolidinone (S)-9 and produced the desired product in 11% overall yield.6628

    Tidal Forces in Reissner-Nordström Spacetimes

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    We analyze the tidal forces produced in the spacetime of Reissner-Nordstr\"om black holes. We point out that the radial component of the tidal force changes sign just outside the event horizon if the charge-to-mass ratio is close to 11 unlike in Schwarzschild spacetime of uncharged black holes, and that the angular component changes sign between the outer and inner horizons. We solve the geodesic deviation equations for radially falling bodies towards the charged black hole. We find, for example, that the radial component of the geodesic deviation vector starts decreasing inside the event horizon unlike in the Schwarzschild case

    GESTAÇÃO DE RISCO: PERCEPÇÃO E SENTIMENTOS DAS GESTANTES COM AMNIORREXE PREMATURA

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    Premature amniorrhexis, risky pregnancy, became a global concern because of the harm to the mother and fetus. Aim to identify the knowledge of women of premature amniorrhexis and get to know their perceptions and their feelings about this pathology. Descriptive study with a qualitative approach, developed in a public maternity ward. 11 women participated while hospitalized with a diagnosis of premature amniorrhexis, in the months of September and October 2007. The collection of semi-structured data was used, from which emerged the categories: Women's knowledge in relation to premature amniorrhexis, requiring information, and their feelings experienced, and reaction before their water broke. The results showed that women know little of the disease, or fear for the life of their children, and do not know what to do before that. Additionally health care professionals should regard women as human beings that need support and understanding.Amniorrexe prematuro, embarazo de riesgo, se convirtió en preocupación mundial debido a los agravios en la gestante y en el feto. Objetivamos identificar el conocimiento de las gestantes sobre amniorrexe prematura y conocer sus percepciones y sus sentimientos ante esta patología. Estudio descriptivo con un enfoque cualitativo, desarrollado en una maternidad pública. Participaron 11 gestantes hospitalizadas con diagnóstico de amniorrexe prematura, en los meses de septiembre y octubre de 2007. Se utilizó en la recogida de datos entrevista semi-estructurada a partir de la cual surgieron las categorías: conocimiento de las gestantes en relación con amniorrexe prematura, que requieren la información, los sentimientos experimentados, la reacción ante la ruptura de la bolsa de aguas. Los resultados mostraron que las mujeres saben poco de la enfermedad, el temor por la vida de sus hijos y no saben qué hacer ante esta situación. De ahí la necesidad de los profesionales de la salud de mirar a las gestantes como seres que necesitan de apoyo y comprensión.Amniorrexe prematura, gestação de risco, tornou-se preocupação mundial devido os agravos na gestante e no feto. Objetivamos identificar o conhecimento de gestantes sobre amniorrexe prematura e conhecer suas percepções e seus sentimentos diante desta patologia. Estudo descritivo com abordagem qualitativa, desenvolvido em uma maternidade pública. Participaram 11 gestantes internadas com o diagnóstico de amniorrexe prematura, nos meses de setembro e outubro de 2007. Utilizou-se na coleta de dados entrevista semi-estruturada de onde emergiram as categorias: conhecimento das gestantes em relação à amniorrexe prematura, necessitando de informações, sentimentos vivenciados, reação diante do rompimento da bolsa das águas. Os resultados revelaram que as gestantes pouco conhecem da patologia, temem pela vida dos filhos e não sabem o que fazer diante dessa situação. Consideramos então a necessidade dos profissionais de saúde olhar para as gestantes como seres que necessitam de apoio e compreensão

    An evaluation of enteral nutrition practices and nutritional provision in children during the entire length of stay in critical care

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    <b>Background</b> Provision of optimal nutrition in children in critical care is often challenging. This study evaluated exclusive enteral nutrition (EN) provision practices and explored predictors of energy intake and delay of EN advancement in critically ill children.<p></p> <b>Methods</b> Data on intake and EN practices were collected on a daily basis and compared against predefined targets and dietary reference values in a paediatric intensive care unit. Factors associated with intake and advancement of EN were explored.<p></p> <b>Results</b> Data were collected from 130 patients and 887 nutritional support days (NSDs). Delay to initiate EN was longer in patients from both the General Surgical and congenital heart defect (CHD) Surgical groups [Median (IQR); CHD Surgical group: 20.3 (16.4) vs General Surgical group: 11.4 (53.5) vs Medical group: 6.5 (10.9) hours; p <= 0.001]. Daily fasting time per patient was significantly longer in patients from the General Surgical and CHD Surgical groups than those from the Medical group [% of 24 h, Median (IQR); CHD Surgical group: 24.0 (29.2) vs General Surgical group: 41.7 (66.7) vs Medical group: 9.4 (21.9); p <= 0.001]. A lower proportion of fluids was delivered as EN per patient (45% vs 73%) or per NSD (56% vs 73%) in those from the CHD Surgical group compared with those with medical conditions. Protein and energy requirements were achieved in 38% and 33% of the NSDs. In a substantial proportion of NSDs, minimum micronutrient recommendations were not met particularly in those patients from the CHD Surgical group. A higher delivery of fluid requirements (p < 0.05) and a greater proportion of these delivered as EN (p < 0.001) were associated with median energy intake during stay and delay of EN advancement. Fasting (31%), fluid restriction (39%) for clinical reasons, procedures requiring feed cessation and establishing EN (22%) were the most common reasons why target energy requirements were not met.<p></p> <b>Conclusions</b> Provision of optimal EN support remains challenging and varies during hospitalisation and among patients. Delivery of EN should be prioritized over other "non-nutritional" fluids whenever this is possible.<p></p&gt

    New occurrence of B chromosomes in Partamonahelleri (Friese, 1900) (Hymenoptera, Meliponini)

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    Cytogenetic analyses of the stingless bee Partamona helleri collected in the state of Bahia, Northeast Brazil revealed the chromosome numbers n = 18 in the haploid males and 2n = 35 in the diploid females. All karyotypes displayed one large acrocentric B chromosome, which differs from the minute B chromosomes previously described in the populations from southeastern Brazil. Giemsa staining, C-banding and DAPI/CMA3 fluorochrome staining also revealed a remarkable interpopulational divergence regarding both the regular karyotype and the B chromosomes. The B chromosomes found in the samples from Jequié, Bahia, were entirely heterochromatic, while those found in Cravolândia, Bahia, displayed a euchromatic portion at the telomeric end of the long arm. CMA 3 labeling sites varied from seven to eight between the two localities in Bahia, due to the presence of an extra GC-rich block in the karyotype of the samples from Jequié. This is the first report of a large B chromosome in P. helleri and reveals the occurrence of a geographic differentiation within this species

    Lessons to be learnt from Leishmania studies

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    Leishmaniasis is a disease caused by infection with the protozoan parasite Leishmania, which is responsible for three main types of disease: cutaneous leishmaniasis, visceral leishmaniasis and mucocutaneous leishmaniasis based to the site of infection for the particular species. This presents a major challenge to successful drug treatment, as a drug must not only reach antileishmanial concentrations in infected macrophages, the parasites' host cell, but also reach infected cells in locations specific to the type of disease. In this paper we discuss how studies using Leishmania have contributed to our knowledge on how drug delivery systems can be used to improve drug efficacy and delivery
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