332 research outputs found

    Counting function fluctuations and extreme value threshold in multifractal patterns: the case study of an ideal 1/f1/f noise

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    To understand the sample-to-sample fluctuations in disorder-generated multifractal patterns we investigate analytically as well as numerically the statistics of high values of the simplest model - the ideal periodic 1/f1/f Gaussian noise. By employing the thermodynamic formalism we predict the characteristic scale and the precise scaling form of the distribution of number of points above a given level. We demonstrate that the powerlaw forward tail of the probability density, with exponent controlled by the level, results in an important difference between the mean and the typical values of the counting function. This can be further used to determine the typical threshold xmx_m of extreme values in the pattern which turns out to be given by xm(typ)=2clnlnM/lnMx_m^{(typ)}=2-c\ln{\ln{M}}/\ln{M} with c=3/2c=3/2. Such observation provides a rather compelling explanation of the mechanism behind universality of cc. Revealed mechanisms are conjectured to retain their qualitative validity for a broad class of disorder-generated multifractal fields. In particular, we predict that the typical value of the maximum pmaxp_{max} of intensity is to be given by lnpmax=αlnM+32f(α)lnlnM+O(1)-\ln{p_{max}} = \alpha_{-}\ln{M} + \frac{3}{2f'(\alpha_{-})}\ln{\ln{M}} + O(1), where f(α)f(\alpha) is the corresponding singularity spectrum vanishing at α=α>0\alpha=\alpha_{-}>0. For the 1/f1/f noise we also derive exact as well as well-controlled approximate formulas for the mean and the variance of the counting function without recourse to the thermodynamic formalism.Comment: 28 pages; 7 figures, published version with a few misprints corrected, editing done and references adde

    Using [C II] 158 μm Emission from Isolated ISM Phases as a Star Formation Rate Indicator

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    The brightest observed emission line in many star-forming galaxies is the [C II] 158 μm line, making it detectable up to z ~ 7. In order to better understand and quantify the [C II] emission as a tracer of star formation, the theoretical ratio between the [N II] 205 μm emission and the [C II] 158 μm emission has been employed to empirically determine the fraction of [C II] emission that originates from the ionized and neutral phases of the interstellar medium (ISM). Sub-kiloparsec measurements of the [C II] 158 μm and [N II] 205 μm lines in nearby galaxies have recently become available as part of the Key Insights in Nearby Galaxies: a Far Infrared Survey with Herschel (KINGFISH) and Beyond the Peak programs. With the information from these two far-infrared lines along with the multi-wavelength suite of KINGFISH data, a calibration of the [C II] emission line as a star formation rate (SFR) indicator and a better understanding of the [C II] deficit are pursued. [C II] emission is also compared to polycyclic aromatic hydrocarbon (PAH) emission in these regions to compare photoelectric heating from PAH molecules to cooling by [C II] in the neutral and ionized phases of the ISM. We find that the [C II] emission originating in the neutral phase of the ISM does not exhibit a deficit with respect to the infrared luminosity and is therefore preferred over the [C II] emission originating in the ionized phase of the ISM as an SFR indicator for the normal star-forming galaxies included in this sample

    Entre a fronteira do aprender e o fracasso escolar no Transtorno de Déficit de Atenção e Hiperatividade / Between the frontier of learning and school failure in Attention Deficit Hyperactivity Disorder

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    A escolarização da criança com Transtorno de Déficit de Atenção e Hiperatividade (TDAH) ainda constitui um grande desafio, visto que além das dificuldades em responder às demandas acadêmicas em termos de aprendizagem, o padrão de interações sociais, com os colegas e os professores, também impõe obstáculos para a participação efetiva em todas as atividades do ambiente escolar. Levantar fatores que levam as crianças com TDAH a não aprenderam na escola foi o objetivo deste estudo longitudinal retrospectivo do tipo coorte histórico que utilizou a revisão de 49 prontuários, com 3 unidades de análise: dados pessoais e socioeconômicos, dados de formação educacional e dados específicos contendo questões dicotômicas de resposta única. Os dados mostrados aqui para os portadores de TDHA da amostra são: 4,1% de histórico de adoção, 2% de existência de patologia de base, 22,4% de histórico de drogadição para o pai e 10,2% para a mãe. Dado discordante da literatura: 87,7% de não reprovação. É primordial buscar constantemente conhecer mais acerca desse transtorno, tanto por parte dos profissionais da educação quanto da família, desde o diagnóstico até o tratamento, de forma a contribuir para oferecer, no âmbito escolar, um ensino significativo para os portadores de TDAH

    Chandra X-ray Observations of the Spiral Galaxy M81

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    A Chandra X-Ray Observatory ACIS-S imaging observation is used to study the population of X-ray sources in the nearby Sab galaxy M81 (NGC 3031). A total of 177 sources are detected with 124 located within the D25 isophote to a limiting X-ray luminosity of 3e36 ergs/cm2/s. Source positions, count rates, luminosities in the 0.3-8.0 keV band, limiting optical magnitudes, and potential counterpart identifications are tabulated. Spectral and timing analysis of the 36 brightest sources are reported including the low-luminosity active galactic nucleus, SN 1993J, and the Einstein-discovered ultra-luminous X-ray source X6.Comment: 27 pages, 17 figures, 2 tables, submitted to Ap

    Achalasia - An Update

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    Achalasia is an esophageal motility disorder of unknown cause, characterized by aperistalsis of the esophageal body and impaired lower esophageal sphincter relaxation. Patients present at all ages, primarily with dysphagia for solids/liquids and bland regurgitation. The diagnosis is suggested by barium esophagram and confirmed by esophageal manometry. Achalasia cannot be cured. Instead, our goal is to relieve symptoms, improve esophageal emptying and prevent the development of megaesophagus. The most successful therapies are pneumatic dilation and surgical myotomy. The overall success rate of graded pneumatic dilation is 78%, with women and older patients responding best. Laparoscopic myotomy, usually combined with a partial fundoplication, has an overall success rate of 87%. Young patients, especially men, are the best candidates for surgical myotomy. Botulinum toxin injection into the lower esophageal sphincter and smooth muscle relaxants are usually reserved for older patients or those with co-morbid illness. The prognosis for achalasia patients to return to near normal swallowing is good, but the disease is rarely "cured" with a single procedure and intermittent touch-up procedures may be required

    Complete genomic sequences of Propionibacterium freudenreichii phages from Swiss cheese reveal greater diversity than Cutibacterium (formerly Propionibacterium) acnes phages

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    Background:A remarkable exception to the large genetic diversity often observed for bacteriophages infecting aspecific bacterial host was found for the Cutibacterium acnes (formerly Propionibacterium acnes) phages, which are highly homogeneous. Phages infecting the related species, which is also a member of the Propionibacteriaceae family, Propionibacterium freudenreichii , a bacterium used in production of Swiss-type cheeses, have also been described and are common contaminants of the cheese manufacturing process. However, little is known about their genetic composition and diversity.Results:We obtained seven independently isolated bacteriophages that infect P. freudenreichii from Swiss-typecheese samples, and determined their complete genome sequences. These data revealed that all seven phage isolates are of similar genomic length and GC% content, but their genomes are highly diverse, including genes encoding the capsid, tape measure, and tail proteins. In contrast to C. acnes phages, all P. freudenreichii phage genomes encode a putative integrase protein, suggesting they are capable of lysogenic growth. This is supported by the finding of related prophages in some P. freudenreichii strains. The seven phages could further be distinguished as belonging to two distinct genomic types, or ‘ clusters ’ , based on nucleotide sequences, and host range analyses conducted on a collection of P. freudenreichii strains show a higher degree of host specificity than is observed for the C. acnes phages.Conclusions:Overall, our data demonstrate P. freudenreichii bacteriophages are distinct from C. acnes phages, asevidenced by their higher genetic diversity, potential for lysogenic growth, and more restricted host ranges. This suggests substantial differences in the evolution of these related species from the Propionibacteriaceae family and their phages, which is potentially related to their distinct environmental niches

    Using [C II] 158 μm Emission from Isolated ISM Phases as a Star Formation Rate Indicator

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    The brightest observed emission line in many star-forming galaxies is the [C II] 158 μm line, making it detectable up to z ~ 7. In order to better understand and quantify the [C II] emission as a tracer of star formation, the theoretical ratio between the [N II] 205 μm emission and the [C II] 158 μm emission has been employed to empirically determine the fraction of [C II] emission that originates from the ionized and neutral phases of the interstellar medium (ISM). Sub-kiloparsec measurements of the [C II] 158 μm and [N II] 205 μm lines in nearby galaxies have recently become available as part of the Key Insights in Nearby Galaxies: a Far Infrared Survey with Herschel (KINGFISH) and Beyond the Peak programs. With the information from these two far-infrared lines along with the multi-wavelength suite of KINGFISH data, a calibration of the [C II] emission line as a star formation rate (SFR) indicator and a better understanding of the [C II] deficit are pursued. [C II] emission is also compared to polycyclic aromatic hydrocarbon (PAH) emission in these regions to compare photoelectric heating from PAH molecules to cooling by [C II] in the neutral and ionized phases of the ISM. We find that the [C II] emission originating in the neutral phase of the ISM does not exhibit a deficit with respect to the infrared luminosity and is therefore preferred over the [C II] emission originating in the ionized phase of the ISM as an SFR indicator for the normal star-forming galaxies included in this sample
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