563 research outputs found

    Design patterns and software techniques for large-scale, open and reproducible data reduction

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    The preparation for the construction of the Square Kilometre Array, and the introduction of its operational precursors, such as LOFAR and MeerKAT, mark the beginning of an exciting era for astronomy. Impressive new data containing valuable science just waiting for discovery is already being generated, and these devices will produce far more data than has ever been collected before. However, with every new data instrument, the data rates grow to unprecedented quantities of data, requiring novel new data-processing tools. In addition, creating science grade data from the raw data still requires significant expert knowledge for processing this data. The software used is often developed by a scientist who lacks proper training in software development skills, resulting in the software not progressing beyond a prototype stage in quality. In the first chapter, we explore various organisational and technical approaches to address these issues by providing a historical overview of the development of radioastronomy pipelines since the inception of the field in the 1940s. In that, the steps required to create a radio image are investigated. We used the lessons-learned to identify patterns in the challenges experienced, and the solutions created to address these over the years. The second chapter describes the mathematical foundations that are essential for radio imaging. In the third chapter, we discuss the production of the KERN Linux distribution, which is a set of software packages containing most radio astronomy software currently in use. Considerable effort was put into making sure that the contained software installs appropriately, all items next to one other on the same system. Where required and possible, bugs and portability fixes were solved and reported with the upstream maintainers. The KERN project also has a website, and issue tracker, where users can report bugs and maintainers can coordinate the packaging effort and new releases. The software packages can be used inside Docker and Singularity containers, enabling the installation of these packages on a wide variety of platforms. In the fourth and fifth chapters, we discuss methods and frameworks for combining the available data reduction tools into recomposable pipelines and introduce the Kliko specification and software. This framework was created to enable end-user astronomers to chain and containerise operations of software in KERN packages. Next, we discuss the Common Workflow Language (CommonWL), a similar but more advanced and mature pipeline framework invented by bio-informatics scientists. CommonWL is supported by a wide range of tools already; among other schedulers, visualisers and editors. Consequently, when a pipeline is made with CommonWL, it can be deployed and manipulated with a wide range of tools. In the final chapter, we attempt something unconventional, applying a generative adversarial network based on deep learning techniques to perform the task of sky brightness reconstruction. Since deep learning methods often require a large number of training samples, we constructed a CommonWL simulation pipeline for creating dirty images and corresponding sky models. This simulated dataset has been made publicly available as the ASTRODECONV2019 dataset. It is shown that this method is useful to perform the restoration and matches the performance of a single clean cycle. In addition, we incorporated domain knowledge by adding the point spread function to the network and by utilising a custom loss function during training. Although it was not possible to improve the cleaning performance of commonly used existing tools, the computational time performance of the approach looks very promising. We suggest that a smaller scope should be the starting point for further studies and optimising of the training of the neural network could produce the desired results

    Making Teams More Resilient:Effects of Shared Transformational Leadership Training on Resilience

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    Resilience is of great importance to teams operating in complex environments, such as command and control teams. Team resilience is the ability of teams to respond to sudden, unanticipated demands for performance quickly and with minimum decrement of performance. The objective of this study was to design and test a training intervention to make teams more resilient. In a between-subjects design utilizing a sample of 35 three-person teams, two training manipulations were compared to each other and a control group. Higher levels of team resilience were found when shared leadership was enforced through brief training of transformational-leadership behaviors. This study demonstrated the effectiveness of a relatively small training intervention in boosting resilience

    A mycotic aneurysm of the abdominal aorta in a child

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    A 6-year-old boy with a previous history of intracardiac correction of a partial atrioventricular canal defect presented with infective endocarditis. Despite antibiotic therapy and reoperation, he developed a mycotic abdominal aneurysm. In situ aortoiliac reconstruction with a prosthesis and an omental flap was performed. At follow-up after 2 {Mathematical expression} years there were no signs of prosthetic infection or problems with the anastomoses

    Simultaneous Epstein Barr Virus and Cytomegalovirus Infection Accompanied by Leiomyomatous Change in a Well-Differentiated Liposarcoma in a Patient With Long-Term Corticosteroid Treatment

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    Patient. A 59-year-old woman presented with a large tumour of the abdominal wall. She had been taking corticosteroids for severe chronic obstructive pulmonary disease for 15 years. On CT scan the tumour had the characteristics of lipomatous tissue with a dense core

    Long-term pulmonary sequelae in children with congenital diaphragmatic hernia.

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    Neonates with congenital diaphragmatic hernia (CDH) often suffer from respiratory insufficiency due to lung hypoplasia and pulmonary hypertension. Artificial ventilation is frequently required, and this leads to a high incidence of bronchopulmonary dysplasia. Long-term follow-up studies have shown persisting airway obstruction. To evaluate the long-term pulmonary sequelae in CDH, we studied 40 CDH patients of age 7 to 18 yr (median 11.7 yr) and 65 age-matched controls without CDH and lung hypoplasia who underwent similar neonatal treatment. Mild airway obstruction was found in both groups with more peripheral airway obstruction in CDH patients than in control subjects. Both groups had normal TLC and single-breath carbon monoxide diffusion capacity (DLCO). CDH patients had increased residual volume (RV) and RV/TLC compared with controls. Increased airway responsiveness to methacholine (MCH) was common but bronchoconstriction to inhaled metabisulfite (MBS) was rare both in CDH and control subjects. We conclude that this group of CDH patients has minor residual lung function impairment. Mild airway obstruction and increased airway responsiveness to inhaled MCH but not to MBS suggest that structural changes in distal airways are involved and not autonomic nerve dysfunction. Both artificial ventilation in the neonatal period and residual lung hypoplasia seem important determinants of persistent lung function abnormalities in CDH patients

    New energy carriers in vehicles and their impact on confined infrastructures Overview of previous research and research needs

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    International audienceThe global warming debate forces the vehicle industry to come up with new environmentally friendly solutions. In 10 years time, or even faster depending on the pressure from different governments in particular in Europe, vehicles will not only use gasoline, diesel and LPG, but also CNG, Hydrogen, ethanol, DME and other bio-fuels, as well as batteries and fuel cells. This quick development and the diversity of new energy carriers can jeopardize the safety in underground infrastructures such as tunnels or car parks. This can cause a major drawback in the adoption of new energy carriers as regulators or operators may prohibit use of these vehicles in underground systems if no new relevant measures will be taken. Unclear situation will also affect the implementation of international policies aiming at reducing the environmental footprint and especially CO2 emission in road traffic. The problem became clear after a workshop with the vehicle industry, tunnel operators, authorities, and safety experts organised in November 2008 by L-surF Services with the support of ITA-COSUF, ECTP and HYSAFE. This workshop demonstrated that the construction sector lacks appropriate design data and tools as well as knowledge to build safe underground infrastructure compatible with a diversity of new and alternative energy carriers. Vehicle industry, infrastructure operators and regulators have not yet addressed this problem. In a first part, an overview of the regulatory situation regarding safety and security of the admission of new energy carriers for vehicles in underground infrastructures is presented. Then, a detailed review of previous relevant research projects performed makes it possible to formulate recommendations in terms of a strategic research & development agenda. The overview shows that it is necessary to develop an integrated risk assessment and management method specific for underground transport systems, metros and hubs in confined spaces taking into account the "emerging risk" aspects

    Islet cell cytoplasmic antibody reactivity in midgestational human fetal pancreas

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    The reactivity of islet cell cytoplasmic antibodies (ICA)-positive and ICA-negative sera of recent onset type 1 diabetic patients was studied in human fetal pancreata of 12-18 weeks' gestation and compared with the reactivity of these sera in adult human control pancreata. The aims of the study were: (1) to observe the presence of ICA staining in human fetal islet cells; (2) to compare endpoint titres (in Juvenile Diabetes Foundation units) of ICA-positive patient sera in fetal pancreata and adult human control pancreata. Ten ICA-positive sera and eight ICA-negative sera from newly diagnosed diabetic patients and four sera from healthy controls were tested on three human adult and eight human fetal pancreata. As in the adult control pancreata. ICA-positive sera reacted to insulin-, glucagon-, and somatostatin-positive cells of fetal pancreata of all gestational ages. This was observed both in single cells and in cells in islet-like cell clusters. Dilution of a reference serum gave similar results in both adult and fetal pancreata. In contrast, the ICA-positive patient sera yielded a striking heterogeneity in fetal as well as in adult pancreata. However, end-point titres between adult and fetal pancreata did not differ significantly (P>0.05). In conclusion, ICA-positive sera from recent onset diabetic patients show that the expression of molecules to which ICA react is present in all islet cells and starts before week 12 of gestation
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