355 research outputs found

    Order and chaos in the local disc stellar kinematics induced by the Galactic bar

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    (Abridged) The Galactic bar causes a characteristic splitting of the disc phase space into regular and chaotic orbit regions which is shown to play an important role in shaping the stellar velocity distribution in the Solar neighbourhood. A detailed orbital analysis within an analytical 2D rotating barred potential reveals that this splitting is mainly dictated by the value of the Hamiltonian H and the bar induced resonances. Test particle and N-body simulations reveal how the decoupled evolution of the disc distribution function in the two kind of regions and the process of chaotic mixing lead to overdensities in the H>H_12 chaotic part of the u-v velocity distributions outside corotation, where H_12 is the effective potential at the Lagrangian points L_1/2. In particular, for realistic space positions of the Sun near or slightly beyond the outer Lindblad resonance and if u is defined positive towards the anti-centre, the eccentric quasi-periodic orbits trapped around the stable x1(1) orbits - i.e. the bar-aligned closed orbits which asymptotically become circular at larger distances - produce a broad u<0 regular arc in velocity space extending within the H>H_12 zone, whereas the corresponding u>0 region appears as an overdensity of chaotic orbits forced to avoid that arc. This chaotic overdensity provides an original interpretation, distinct from the anti-bar elongated quasi-periodic orbit interpretation proposed by Dehnen (2000), for the prominent stream of high asymmetric drift and predominantly outward moving stars clearly emerging from the Hipparcos data. The effects of spiral arms and of molecular clouds are also briefly discussed within this context.Comment: 25 pages, 20 figures (3 in gif format). A&A, in press. Full resolution postscript paper (5Mb) and MPEG movies available at http://www.mso.anu.edu.au/~fux/streams.htm

    Assimilation of All-Weather GMI and ATMS Observations into HWRF

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    We propose a novel Bayesian Monte Carlo Integration (BMCI) technique to retrieve the profiles of temperature, water vapor, and cloud liquid/ice water content from microwave cloudy measurements in the presence of TCs. These retrievals then can either be directly used by meteorologists to analyze the structure of TCs or be assimilated to provide accurate initial conditions for the NWP models. The technique is applied to the data from the Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar-orbiting Partnership (NPP) and Global Precipitation Measurement (GPM) Microwave Imager (GMI)

    Assimilation of All-Weather GMI and ATMS Observations into HWRF

    Get PDF
    We propose a novel Bayesian Monte Carlo Integration (BMCI) technique to retrieve the profiles of temperature, water vapor, and cloud liquid/ice water content from microwave cloudy measurements in the presence of TCs. These retrievals then can either be directly used by meteorologists to analyze the structure of TCs or be assimilated to provide accurate initial conditions for the NWP models. The technique is applied to the data from the Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar-orbiting Partnership (NPP) and Global Precipitation Measurement (GPM) Microwave Imager (GMI)

    Fear and fitness: An evolutionary analysis of anxiety disorders

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    This article reviews the evolutionary origins and functions of the capacity for anxiety, and relevant clinical and research issues. Normal anxiety is an emotion that helps organisms defend against a wide variety of threats. There is a general capacity for normal defensive arousal, and subtypes of normal anxiety protect against particular kinds of threats. These normal subtypes correspond somewhat to mild forms of various anxiety disorders. Anxiety disorders arise from dysregulation of normal defensive responses, raising the possibility of a hypophobic disorder (too little anxiety). If a drug were discovered that abolished all defensive anxiety, it could do harm as well as good. Factors that have shaped anxiety-regulation mechanisms can explain prepotent and prepared tendencies to associate anxiety more quickly with certain cues than with others. These tendencies lead to excess fear of largely archaic dangers, like snakes, and too little fear of new threats, like cars. An understanding of the evolutionary origins, functions, and mechanisms of anxiety suggests new questions about anxiety disorders.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31354/1/0000265.pd

    The Economic Theory of Housing Demand: A Critical Review

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    Despite thirty years of modeling housing markets, housing analysts still have difficulty accurately assessing housing demand. This article reviews the current state of the art in economic modeling of housing demand determinants and suggests a future direction for further research. The fully developed economic theory of the housing market for analyzing housing decisions is the neoclassical consumer theory of housing demand. The review of the various modifications that have been made to better operationalize the imperfect and noncompetitive features of the housing market show that these modifications have been introduced in several partial models. These models include tenure choice models, search models, mobility models, and housing trait models. There is currently no single model that incorporates all of the modifications attempted in these partial models. In fact, it may be impossible to operationalize and incorporate all of the modifications of the neoclassical model into a single model. Therefore, the most feasible and conceptually correct research strategy to advance our understanding of housing consumption decisions is to analyze the impact of demographic and social processes on housing consumption decisions. There is a need to research how to include demographic and sociological constructs that capture the attitudes, preferences, and perceptions of the consumer into the classical economic model of housing demand.

    Assessing Vividness of Mental Imagery: The Plymouth Sensory Imagery Questionnaire

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    Publisher allows archiving of submitted msMental imagery may occur in any sensory modality, although visual imagery has been most studied. A sensitive measure of the vividness of imagery across a range of modalities is needed: the shorter version of Bett’s QMI (Sheehan, 1967) uses outdated items and has an unreliable factor structure. We report the development and initial validation of the Plymouth Sensory Imagery Questionnaire (Psi-Q) comprising items for each of the following modalities: Vision, Sound, Smell, Taste, Touch, Bodily Sensation and Emotional Feeling. An Exploratory Factor Analysis on a 35-item form indicated that these modalities formed separate factors, rather than a single imagery factor, and this was replicated by confirmatory factor analysis. The Psi-Q was validated against the Spontaneous Use of Imagery Scale (Reisberg, Pearson & Kosslyn, 2003) and Marks’ (1995) Vividness of Visual Imagery Questionnaire-2. A short 21-item form comprising the best three items from the seven factors correlated with the total score and subscales of the full form, and with the VVIQ-2. Inspection of the data shows that while visual and sound imagery is most often rated as vivid, individuals who rate one modality as strong and the other as weak are not uncommon. Findings are interpreted within a working memory framework and point to the need for further research to identify the specific cognitive processes underlying the vividness of imagery across sensory modalities

    Pseudomonas oryzihabitans sepsis in a 1-year-old child with multiple skin rashes: a case report.

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    BACKGROUND: Pseudomonas oryzihabitans is a Pseudomonas bacterial organism rarely implicated in human infections. The bacterium has been isolated in a few reported cases of neurosurgical infections and patients with end-stage cirrhosis, sickle cell disease, and community-acquired urinary tract infections. Limited information exists in developing countries, however, because of the lack of advanced microbiological tools for identification and characterization of this bacterium. This case report describes the isolation of a rare Pseudomonas bacterium in a patient presenting with sepsis and skin infection. CASE PRESENTATION: A 1-year-old girl was presented to a hospital in the northeastern part of Ghana with a 1-week history of pustular rashes on her scalp and neck, which occasionally ruptured, along with discharge of yellowish purulent fluid. The child is of Mole-Dagbon ethnicity and hails from the northern part of Ghana. Pseudomonas oryzihabitans was identified in the patient's blood culture using the 16S ribosomal deoxyribonucleic acid sequencing technique. The rash on the patient's scalp and skin resolved after continuous treatment with gentamicin while her condition improved clinically. CONCLUSIONS: This finding suggests the potential of this bacterium to cause disease in unsuspected situations and emphasizes the need to have evidence for the use of the appropriate antibiotic in clinical settings, particularly in rural settings in Africa. It also brings to the fore the unreliability of conventional methods for identification of Pseudomonas bacteria in clinical samples and thus supports the use of 16S ribosomal deoxyribonucleic acid in making the diagnosis

    Epidemiological Change of Atopic Dermatitis and Food Allergy in School-Aged Children in Korea between 1995 and 2000

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    Little is known about the prevalence of atopic dermatitis and food allergy outside North America and Europe. We evaluated the prevalence of atopic dermatitis and food allergy with the comparison of prevalence between 1995 and 2000 in Korea and evaluated the correlation of prevalence between atopic dermatitis and food allergy. A cross-sectional questionnaire survey was conducted on random samples of schoolchildren 6 to 14 yr at two time points, 1995 and 2000 throughout Korea. The last twelve months prevalence of atopic dermatitis in Korean school-aged children was increased from 1995 to 2000. The twelve-month prevalence of atopic dermatitis and food allergy were higher in Seoul than in any other provincial cities in 1995, but the prevalence of both diseases in Seoul and Provincial Centers became to be similar in 2000. The rate responded to food allergy of children with atopic dermatitis (9.5%) was lower than that of the western countries (60%). And our data demonstrated paternal and maternal allergy history is very significantly correlated to developing atopic dermatitis in their offspring. The further objective evaluations are required to confirm these outcomes because the environmental and risk factors may be different among the countries according to their living cultures
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