1,467 research outputs found

    Fast reactor core heat removal

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    New approaches to probing Minkowski functionals

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    We generalize the concept of the ordinary skew-spectrum to probe the effect of non-Gaussianity on the morphology of cosmic microwave background (CMB) maps in several domains: in real space (where they are commonly known as cumulant-correlators), and in harmonic and needlet bases. The essential aim is to retain more information than normally contained in these statistics, in order to assist in determining the source of any measured non-Gaussianity, in the same spirit as Munshi & Heavens skew-spectra were used to identify foreground contaminants to the CMB bispectrum in Planck data. Using a perturbative series to construct the Minkowski functionals (MFs), we provide a pseudo-C based approach in both harmonic and needlet representations to estimate these spectra in the presence of a mask and inhomogeneous noise. Assuming homogeneous noise, we present approximate expressions for error covariance for the purpose of joint estimation of these spectra. We present specific results for four different models of primordial non-Gaussianity local, equilateral, orthogonal and enfolded models, as well as non-Gaussianity caused by unsubtracted point sources. Closed form results of nextorder corrections to MFs too are obtained in terms of a quadruplet of kurt-spectra. We also use the method of modal decomposition of the bispectrum and trispectrum to reconstruct the MFs as an alternative method of reconstruction of morphological properties of CMB maps. Finally, we introduce the odd-parity skew-spectra to probe the odd-parity bispectrum and its impact on the morphology of the CMB sky. Although developed for the CMB, the generic results obtained here can be useful in other areas of cosmology

    Molecular Organization and Patterning of the Medulla Oblongata in Health and Disease

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    The medulla oblongata, located in the hindbrain between the pons and the spinal cord, is an important relay center for critical sensory, proprioceptive, and motoric information. It is an evolutionarily highly conserved brain region, both structural and functional, and consists of a multitude of nuclei all involved in different aspects of basic but vital functions. Understanding the functional anatomy and developmental program of this structure can help elucidate potential role(s) of the medulla in neurological disorders. Here, we have described the early molecular patterning of the medulla during murine development, from the fundamental units that structure the very early medullary region into 5 rhombomeres (r7–r11) and 13 different longitudinal progenitor domains, to the neuronal clusters derived from these progenitors that ultimately make-up the different medullary nuclei. By doing so, we developed a schematic overview that can be used to predict the cell-fate of a progenitor group, or pinpoint the progenitor domain of origin of medullary nuclei. This schematic overview can further be used to help in the explanation of medulla-related symptoms of neurodevelopmental disorders, e.g., congenital central hypoventilation syndrome, Wold–Hirschhorn syndrome, Rett syndrome, and Pitt–Hopkins syndrome. Based on the genetic defects seen in these syndromes, we can use our model to predict which medullary nuclei might be affected, which can be used to quickly direct the research into these diseases to the likely affected nuclei

    The effect of a multispecies probiotic on the composition of the faecal microbiota and bowel habits in chronic obstructive pulmonary disease patients treated with antibiotics

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    Short-term antibiotic treatment profoundly affects the intestinal microbiota, which may lead to sustained changes in microbiota composition. Probiotics may restore such a disturbance. The objective of the present study was to investigate the effect of a multispecies probiotic on the faecal microbiota during and after antibiotic intake in patients with a history of frequent antibiotic use. In this randomised, placebo-controlled, double-blind study, thirty chronic obstructive pulmonary disease (COPD) patients treated with antibiotics for a respiratory tract infection received 5 g of a multispecies probiotic or placebo twice daily for 2 weeks. Faecal samples were collected at 0, 7, 14 and 63 d. Changes in the composition of the dominant faecal microbiota were determined by PCR-denaturing gradient gel electrophoresis (DGGE). Changes in bacterial subgroups were determined by quantitative PCR and culture. Bowel movements were scored daily according to the Bristol stool form scale. During and after antibiotic treatment, DGGE-based similarity indices (SI) were high ( >/= 84 %) and band richness was relatively low, both remaining stable over time. No difference in SI was observed between patients with and without diarrhoea-like bowel movements. The multispecies probiotic had a modest effect on the bacterial subgroups. Nevertheless, it affected neither the composition of the dominant faecal microbiota nor the occurrence of diarrhoea-like bowel movements. The dominant faecal microbiota was not affected by antibiotics in this COPD population, suggesting an existing imbalance of the microbiota, which may also have contributed to the lack of effect by probiotic intak

    A strong web presence can equalize the playing field for long shot candidates in Presidential party nominations

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    While few would doubt that the Internet is now an important component in any election, especially the presidential, what effects does a candidates’ web presence have on their electoral chances, and is this something that they are able to influence? Using data from the 2008 presidential nominations, Dino P. Christenson, Corwin D. Smidt and Costas Panagopoulos investigate how candidate’s web presence differs from traditional indicators of campaign performance and if it can help them to gain greater financial and electoral support. They find that campaign frontrunners have a limited ability to control their web presence, but that outsider candidates can have more success. They also show that candidates with a greater web presence see greater successes in fundraising
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