1,542 research outputs found

    Regenerable metallic oxide systems for removal of carbon dioxide: A concept

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    Design concepts for portable canisters for removal of carbon dioxide are described. One is screen pack configuration consisting of brazed rectangular canister with four metal oxide packs inserted. Other is radial flow canister with perforated central tube. Methods of production and operating principles are presented

    Phosphonium chloride for thermal storage

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    Development of systems for storage of thermal energy is discussed. Application of phosphonium chloride for heat storage through reversible dissociation is described. Chemical, physical, and thermodynamic properties of phosphonium chloride are analyzed and dangers in using phosphonium chloride are explained

    Solid amine compounds as sorbents for carbon dioxide: A concept

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    Solid amine compounds were examined as possible absorbents for removal of carbon dioxide in life support systems of type which may be employed in high altitude aircraft, spacecraft, or submarines. Many solid amine compounds release absorbed carbon dioxide when heated in vacuum, therefore, when properly packaged spent amine compounds can be readily regenerated and put back into service

    Advanced extravehicular protective system Interim report, 1 Jul. 1970 - 31 May 1971

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    Regenerable portable life support systems concepts for EVA use in 1980 and technology assessmen

    Thermal-structural design study of an airframe-integrated Scramjet

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    Design concepts are developed and evaluated for a cooled structures assembly for the Scramjet engine, for engine subsystems mass, volume, and operating requirements, and for the aircraft/engine interface. A thermal protection system was defined that makes it possible to attain a life of 100 hours and 1000 cycles. The coolant equivalence ratio at the Mach 10 maximum thermal loading condition is 0.6, indicating a capacity for airframe cooling. The mechanical design is feasible for manufacture using conventional materials. For the cooled structures in a six-module engine, the mass per unit capture area is 12.4 KN/sq m. The total weight of a six-module engine assembly including the fuel system is 14.73 KN

    Thermal-structural design study of an airframe-integrated Scramjet

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    The development and evaluation of a design concept for the cooled structures assembly for the Scramjet engine is discussed. Development concepts for engine subsystems and design concepts for the aircraft/engine interface are included. A thermal protection system was defined which makes it possible to attain a life of 100 hr and 1000 cycles, the specified goal. The coolant equivalence ratio at the Mach 10 maximum thermal loading condition is 0.6, indicating a capacity for airframe cooling. The mechanical design is feasible for manufacture using conventional materials. For the cooled structures in a six module engine, the mass per unit capture area is 1256 kg/sq m. The total mass of a six module engine assembly including the fuel system is 1502 kg

    Novas opções para o tratamento preventivo da migrânea: revisão com considerações fisiopatológicas

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    BACKGROUND: The pharmacological treatment of migraine may be acute or preventive. Frequent, severe and long-lasting migraine attacks require prophylaxis. Multiple threads of research over the last 15 years have led to the concept that migraine is generated from a hyperexcitable brain. A variety of causes for hyperexcitability of the brain in migraine have been suggested. These causes include low cerebral magnesium levels, mitochondrial abnormalities, dysfunctions related to increased nitric oxide or the existence of a P/Q type calcium channelopathy. The better knowledge about migraine pathophisiology led us to discuss new treatment options. OBJECTIVES: The aim of the present study is to present an evidence-based review of some new drugs or some agents that even though available for a long time, are not frequently used. METHODS/RESULTS: We present a review of anticonvulsants with various mechanisms of action such as lamotrigine, gabapentin, topiramate, tiagabine, levetiracetam and zonisamide. We also review natural products, like riboflavin and magnesium, botulinum toxin A, a specific CGRP antagonist and the anti-asthma medication montelukast, with pathophysiological discussion. CONCLUSIONS: We aimed to present an update of newer or less frequently used preventive migraine therapies, drugs that might reduce the burden and the costs of a disease that should be considered as a public health problem all around the world.INTRODUÇÃO: O tratamento farmacológico da migrânea pode ser dividido em agudo e preventivo. Crises de migrânea severas, de longa duração e incapacitante requerem profilaxia. Múltiplas linhas de pesquisa ao longo dos últimos 15 anos sedimentaram o conceito de que a migrânea é gerada a partir de um cérebro hiperexcitável. Variadas causas para essa hiperexcitabilidade têm sido sugeridas e incluem baixo nível de magnésio cerebral, anormalidades mitocondriais, disfunções relacionadas ao óxido nítrico e a existência de distúrbios nos canais de cálcio do tipo P/Q. O melhor conhecimento sobre a fisiopatologia da migrânea nos permite discutir novas opções terapêuticas. OBJETIVOS: O objetivo do presente estudo é apresentar revisão baseada em evidências de novos agentes e outros que, embora disponíveis há mais tempo, não são freqüentemente utilizados, com considerações fisiopatológicas. MÉTODOS/RESULTADOS: Serão revistos anticonvulsivantes com vários mecanismos de ação, como gabapentina, lamotrigina, topiramato, tiagabina, levetiracetam e zonisamida. Serão revistos também produtos naturais, como riboflavina e magnésio, toxina botulínica do tipo A, um antagonista CGRP específico e uma nova opção para o tratamento da asma, o montelukast. CONCLUSÕES: Objetivamos apresentar artigo de atualização em opções novas ou não freqüentemente utilizadas no tratamento preventivo da migrânea, drogas que podem reduzir o fardo e os custos de uma doença que deve ser considerada um problema de saúde pública em todo o mundo

    Quantitative assessment of chronic lung disease of infancy using computed tomography

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    The aims of this study were to determine whether infants and toddlers with chronic lung disease of infancy (CLDI) have smaller airways and lower lung density compared with full-term healthy controls. Multi-slice computed tomography (CT) chest scans were obtained at elevated lung volumes during a brief respiratory pause in sedated infants and toddlers;38 CLDI were compared with 39 full-term controls. For CLDI subjects, gestational age at birth ranged from 25 to 29 weeks. Airway size was measured for the trachea and the next three to four generations into the right lower lobe;lung volumes and tissue density were also measured. The relationship between airway size and airway generation differed between the CLDI and full-term groups;the sizes of the first and second airway generations were larger in the shorter CLDI than in the shorter full-term subjects. The increased size in the airways in the CLDI subjects was associated with increasing mechanical ventilation time in the neonatal period. CLDI subjects had a greater heterogeneity of lung density compared with full-term subjects. Our results indicate that quantitative analysis of multi-slice CT scans at elevated volumes provides important insights into the pulmonary pathology of infants and toddlers with CLDI

    Mapping assessments instruments for headache disorders against the icf biopsychosocial model of health and disability

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    Headache disorders have a strong impact on sufferers’ lives. However, the “content” of assessment instruments addressing concepts, such as disability and quality of life (QoL), has not comprehensively been addressed. We searched SCOPUS for research papers in which outcome measures were used in adult populations of patients with migraine, tension-type headache (TTH), and cluster headache (CH). The content of single instruments was then mapped against the International Classification of Functioning, Disability, and Health. A total of 150 papers and 26 instruments were included: 15 addressed disability or impact, two addressed work-related difficulties, and nine addressed QoL. Few instruments were commonly used across the conditions and covered domains of functioning were impact on daily life activities, homework, school, and work-related tasks, leisure time, informal and family relations, pain, emotional difficulties, energy level, and impulse control. Most of the research is based on instruments that were developed for migraine, which is critical for CH, and the impact of headache disorders on work-related activities is poorly acknowledged. Further research is needed to expand the scope of headaches impact on daily life activities, and on environmental factors relevant to headache disorders to raise knowledge on the less represented areas, e.g., TTH impact

    Subordinates’ Resistance and Managers’ Evaluations of Subordinates’ Performance

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    The authors explored the validity of two perspectives as to how managers evaluate subordinates who resist downward influence attempts: a uniformly dysfunctional perspective (i.e., managers regard all manifestations of resistance as indicators of ineffective influence and rate subordinates unfavorably when they resist) and a multifunctional perspective (i.e., managers regard some manifestations of resistance as more constructive than others and rate subordinates more favorably when they employ constructive resistance tactics). The results of two studies provided support for an interactive model, which predicts that the uniformly dysfunctional perspective is characteristic of lower quality leader-member exchange (LMX) relationships and that the multifunctional perspective is characteristic of higher quality leader-member exchanges
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