350 research outputs found

    X-Ray crystallographic studies of four organo-metallic compounds

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    Pulmonary Hydatid Cyst with Complicating Aspergillus Infection Presenting as a Refractory Lung Abscess

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    Background Hydatid disease is rare in the United States. Rarely the hydatid cyst can become infected with mycotic organisms, such as Aspergillus . We describe a young male who presents with clinical features of suppurative lung abscess whose workup diagnosed hydatid cyst complicated by Aspergillus co-infection. Case presentation A 27-year-old Peruvian male was hospitalized because of fever, chills, and productive cough of three months’ duration. Clinical features were consistent with a suppurative lung abscess. Significant findings included leukocytosis with eosinophilia and a chest x-ray showing a large lingular lobe thick walled cavity with a wavy irregular fluid level. The patient ultimately underwent surgical resection of the lingular lobe. Examination of the surgical specimen revealed the cavity to be a hydatid cyst. Histologic examination of the cyst wall showed intense inflammation and several septate hyphae of Aspergillus species. The patient recovered fully and has remained in good health. Conclusion A thick-walled cavity and a wavy meniscus constitute unusual features for an ordinary pyogenic lung abscess and suggests other possibilities. Endogenous cases of hydatid disease are uncommon in the United States, with the majority of cases occurring in immigrants. There are few published case reports describing incidental findings of Aspergillus in a hydatid cyst. The rare occurrence of such a condition can lead to a delay in diagnosis and treatment

    On the importance of nonlinear modeling in computer performance prediction

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    Computers are nonlinear dynamical systems that exhibit complex and sometimes even chaotic behavior. The models used in the computer systems community, however, are linear. This paper is an exploration of that disconnect: when linear models are adequate for predicting computer performance and when they are not. Specifically, we build linear and nonlinear models of the processor load of an Intel i7-based computer as it executes a range of different programs. We then use those models to predict the processor loads forward in time and compare those forecasts to the true continuations of the time seriesComment: Appeared in "Proceedings of the 12th International Symposium on Intelligent Data Analysis

    Wegner-Houghton equation and derivative expansion

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    We study the derivative expansion for the effective action in the framework of the Exact Renormalization Group for a single component scalar theory. By truncating the expansion to the first two terms, the potential UkU_k and the kinetic coefficient ZkZ_k, our analysis suggests that a set of coupled differential equations for these two functions can be established under certain smoothness conditions for the background field and that sharp and smooth cut-off give the same result. In addition we find that, differently from the case of the potential, a further expansion is needed to obtain the differential equation for ZkZ_k, according to the relative weight between the kinetic and the potential terms. As a result, two different approximations to the ZkZ_k equation are obtained. Finally a numerical analysis of the coupled equations for UkU_k and ZkZ_k is performed at the non-gaussian fixed point in D<4D<4 dimensions to determine the anomalous dimension of the field.Comment: 15 pages, 3 figure

    Anthropogenic Space Weather

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    Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

    A shooting algorithm for problems with singular arcs

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    In this article we propose a shooting algorithm for a class of optimal control problems for which all control variables appear linearly. The shooting system has, in the general case, more equations than unknowns and the Gauss-Newton method is used to compute a zero of the shooting function. This shooting algorithm is locally quadratically convergent if the derivative of the shooting function is one-to-one at the solution. The main result of this paper is to show that the latter holds whenever a sufficient condition for weak optimality is satisfied. We note that this condition is very close to a second order necessary condition. For the case when the shooting system can be reduced to one having the same number of unknowns and equations (square system) we prove that the mentioned sufficient condition guarantees the stability of the optimal solution under small perturbations and the invertibility of the Jacobian matrix of the shooting function associated to the perturbed problem. We present numerical tests that validate our method.Comment: No. RR-7763 (2011); Journal of Optimization, Theory and Applications, published as 'Online first', January 201

    Cerebral microcirculation and histological mapping after severe head injury: a contusion and acceleration experimental model

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    Background: Cerebral microcirculation after severe head injury is heterogeneous and temporally variable. Microcirculation is dependent upon the severity of injury, and it is unclear how histology relates to cerebral regional blood flow. Objective: This study assesses the changes of cerebral microcirculation blood flow over time after an experimental brain injury model in sheep and contrasts these findings with the histological analysis of the same regions with the aim of mapping cerebral flow and tissue changes after injury. Methods: Microcirculation was quantified using flow cytometry of color microspheres injected under intracardiac ultrasound to ensure systemic and homogeneous distribution. Histological analysis used amyloid precursor protein staining as a marker of axonal injury. A mapping of microcirculation and axonal staining was performed using adjacent layers of tissue from the same anatomical area, allowing flow and tissue data to be available from the same anatomical region. A mixed effect regression model assessed microcirculation during 4 h after injury, and those results were then contrasted to the amyloid staining qualitative score. results: Microcirculation values for each subject and tissue region over time, including baseline, ranged between 20 and 80 ml/100 g/min with means that did not differ statistically from baseline flows. However, microcirculation values for each subject and tissue region were reduced from baseline, although their confidence intervals crossing the horizontal ratio of 1 indicated that such reduction was not statistically significant. Histological analysis demonstrated the presence of moderate and severe score on the amyloid staining throughout both hemispheres. conclusion: Microcirculation at the ipsilateral and contralateral site of a contusion and the ipsilateral thalamus and medulla showed a consistent decline over time. Our data suggest that after severe head injury, microcirculation in predefined areas of the brain is reduced from baseline with amyloid staining in those areas reflecting the early establishment of axonal injuryJudith Bellapart, Kylie Cuthbertson, Kimble Dunster, Sara Diab, David G. Platts, Owen Christopher Raffel, Levon Gabrielian, Adrian Barnett, Jenifer Paratz, Rob Boots and John F. Frase

    Measuring children’s involvement as an indicator of curriculum effectiveness : a curriculum evaluation of a selected child study centre in Singapore

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    This paper presents one aspect of a research project evaluating a curriculum model of a selected child study centre in Singapore. An issue of worldwide interest and concern is the &lsquo;quality of learning&rsquo; debate as it relates to early childhood centres. In Singapore, the government is focusing on expansion in child care settings and increases in the amount of funded training. One of the issues surrounding prior-to-school education raises the question of how one measures the quality of teaching and learning, to describe the value of using, funding and promoting early education. The research reported in this study used a quasi experimental research paradigm to assess one aspect of the quality of a curriculum programme in a child study centre in Singapore. Children aged between 18 months and 6 years (N = 81) participated in the research. Using the observation scale of Laevers&rsquo; Child Involvement Scale, the active involvement of children in learning experiences was measured. The findings are presented and discussed

    Examining the validity of the Athlete Engagement Questionnaire (AEQ) within a Portuguese sport setting

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    Sport psychology literature suggests that understanding engagement levels is pivotal to promote positive sporting experiences among athletes. The purpose of this study was to examine the psychometric properties of the Athlete Engagement Questionnaire among Portuguese sport athletes. Two distinct samples of Portuguese athletes from different competitive levels were collected, and the results of a confirmatory factor analysis demonstrated a good fit of the model to the data. A review of the psychometric properties indicated that all factors showed good composite reliability, convergent validity, and discriminant validity. In addition, a multi-groups analysis showed the invariance of the model in two independent samples providing evidence of cross validity. Implications of these results for scholars and coaches are discussed and guidelines for future studies are suggested
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