Aerospace Medicine and Biology. A continuing bibliography with indexes

This bibliography lists 244 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1981. Aerospace medicine and aerobiology topics are included. Listings for physiological factors, astronaut performance, control theory, artificial intelligence, and cybernetics are included

Exoteric effects at nanoscopic interfaces - Uncommon negative compressibility of nanoporous materials and unexpected cavitation at liquid/liquid interfaces

This PhD thesis is devoted to the investigation of some peculiar effects happening at nanoscopic interfaces between immiscible liquids or liquids and solids via molecular dynamics simulations. The study of the properties of interfaces at a nanoscopic scale is driven by the promise of many interesting technological applications, including: a novel technology for developing both eco-friendly energy storage devices in the form of mechanical batteries, as well as energy dissipation systems and, in particular, shock absorbers for the automotive market; biomedical applications related to cavitation, such as High-Intensity Focused Ultrasound (HIFU) ablation of cancer tissues and localised drug delivery, and many more. The kinetics of phenomena taking places at these scales is typically determined by large free-energy barriers separating the initial and final states, and even intermediate metastable states, when they are present. Because of such barriers, the phenomena we are interested in are "rare events", i.e. the system attempts the crossing of the barrier(s) many times before finally succeeding when an energy fluctuation makes it possible. At the same time, the magnitude of the barrier is determined by the energetics and dynamics of atoms, which forces us to model the system by taking into account both the femtosecond atomistic timescale and the timescale of the relevant phenomena, typically exceeding the former by several orders of magnitude. These longer timescales are inaccessible to standard molecular dynamics, so, in order to tackle this issue, advanced MD techniques need to be employed. The thesis is divided into two parts, corresponding to the main lines of research investigated, which are (I) the interfaces between water and complex nanoporous solids, and (II) planar solid-liquid and liquid-liquid interfaces. Anticipating some results, atomistic simulations helped uncovering the microscopic mechanism behind the (incredibly rare!) giant negative compressibility exhibited by the ZIF-8 metal organic framework (MOF) upon water intrusion. Molecular dynamics simulations also supported experimental results showing how it is possible to change the intermediate intrusion-extrusion performance of ZIF-8 by changing its grain morphology and arrangement, from a fine powder to compact monolith. Free-energy MD calculations allowed to explain the exceptional stability of surface nanobubbles in water, at undersaturated conditions, on a surprisingly wide variety of substrates, characterized by disparate hydrophobicities and gas affinities; and yet, how they catastrophically destabilize in organic solvents. Finally, through simulations, some light was shed upon the working mechanism behind the novelly discovered phenomenon of how the interface between two immiscible liquids can act as a nucleation site for cavitation

Analysis and correction of the helium speech effect by autoregressive signal processing

SIGLELD:D48902/84 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Research and Technology

Johnson Space Center (JSC) accomplishments in new and advanced concepts during 1989 are highlighted. This year, reports are grouped in sections, Medical Science, Solar System Sciences, Space Transportation Technology, and Space Systems Technology. Summary sections describing the role of JSC in each program are followed by descriptions of significant tasks. Descriptions are suitable for external consumption, free of technical jargon, and illustrated to increase ease of comprehension

PREDICTING NECROTIZING ENTEROCOLITIS IN HOSPITALIZED NEONATES

Necrotizing enterocolitis (NEC), a devastating disease of premature bowel, is challenging to predict. The disease is rare, with incompletely understood pathogenesis, rapid onset and progression, and insufficient diagnostic criteria. Using a systematic review of the literature, a cultivated dataset of published neonatal radiographs, and a publicly available neonatal critical care database, this dissertation examines novel approaches to improve predictions of NEC. First, in a review piece, we summarize surgical care for patients with NEC (Chapter 2). We provide a foundational framework to understanding NEC by describing the diverse presentations of the disease and discussing current best practices to reduce NEC-associated morbidity and mortality. Second, we conduct a systematic review of published prognostic models for predicting NEC onset and progression in hospitalized infants (Chapter 3). We find that published models have fair to poor discrimination of NEC outcomes and high risk of bias, limiting model clinical utility. Third, we develop an image classifier to support surgical resident recognition of pneumatosis intestinalis, a radiographic sign of NEC (Chapter 4). We find that a deep convolutional neural network trained on neonatal abdominal radiographs can successfully detect pneumatosis and performs comparably well to senior surgical residents. Fourth, we use the MIMIC III Clinical Database to develop an early warning score for NEC based on routinely available clinical data during an infant's stay in a neonatal intensive care unit (NICU) (Chapter 5). We find that models accurately predict NEC before disease onset, with first NEC risk detection occurring days previously. Fifth, in a perspective piece, we reflect on the promises and challenges of utilizing machine learning methods in NEC prediction and research (Chapter 6). We advocate for policy and practice changes to improve NEC prediction efforts. Overall, this dissertation highlights strengths and limitations of existing NEC prediction models and offers novel solutions to improve predictions of NEC in hospitalized neonates. We hope this dissertation helps researchers in pediatric surgery and neonatology identify steps to improve early detection of NEC, promote timely clinical management, and minimize the high morbidity and mortality of this disease

Novas abordagens para controlar e detetar estirpes enterotóxicas de Staphylococcus aureus

Doutoramento em BiologiaWith 25 million cases of foodborne diseases occurring annually worldwide, food safety is a major concern. Despite considerable efforts to improve food safety, outbreaks of foodborne diseases due to the presence of pathogenic microorganisms, such as Staphylococcus aureus, are well described in the literature. S. aureus is a well-adapted opportunistic pathogen, which is able to grow in numerous types of food, producing an extensive number virulence factors, including enterotoxins, which are responsible for staphylococcal food poisoning. This type of food poisoning is one of the most prevalent foodborne diseases in the world. With an increased demand for safer food, new food preservation technologies have been developed. Among these technologies is high pressure processing (HPP), which is a non-thermal food preservation method that enables the inactivation or control of pathogenic microorganisms and microorganisms responsible for food spoilage, maintaining food properties. The quick and specific detection of pathogenic microorganisms (or of microorganisms responsible for food spoilage) has become increasingly important in the food industry. Usually the detection, and identification of bacteria is performed using traditional methods based on biochemical and/or serological tests and also on molecular methods based on DNA or RNA analysis. However, these methods are costly, time consuming and laborious. Consequently, it is necessary to develop new alternative methods, such as those based on microbial metabolomics, which can be used as a tool to detect microorganisms in the food industry. Microbial metabolomics uses the metabolites released by microorganisms, being able to allow not only the detection and distinction of microbial species, but also the distinction of their strains. One of the objectives of this work was to evaluate the efficacy of HPP treatment for the inactivation of non-enterotoxic and enterotoxic S. aureus strains. Thus, to accomplish this objective, 1) the effectiveness of different treatments (different pressures and holding times were evaluated); 2) the impact of the treatments on virulence factors, fermentation of mannitol and methicillin susceptibility was evaluated; 3) the development of resistance along several successive HPP cycles was evaluated, and 4) the recovery capacity after 14 days of treatment was also assessed. Other objective of this study was to characterize the volatile exometabolome of S. aureus and evaluate its potential to distinguish the enterotoxic strains from the non-enterotoxic strain. For this purpose, 1) the profile of the volatile exometabolome of S. aureus was characterized using an advanced gas chromatography technique; 2) the S. aureus profile was analyzed as a whole and evaluated the presence of specific compounds already described for this species as well as its metabolic origin; 3) a multivariate statistical analysis method was applied in order to obtain a set of volatile compounds responsible for the distinction of the three strains used; and 4) these set of volatile compounds were analyzed in detail in order to explain the differences between strains, thus justifying their separation. The results of inactivation by HPP showed a higher barotolerance of the non-enterotoxic strain (ATCC 6538), not being completely inactivated at 600 MPa for 30 minutes (maintaining a viability of approximately 4 Log CFU.mL-1). The two enterotoxic strains (2153 MA and 2065 MA) were completely inactivated using these treatment conditions. Both strains ATCC 6538 and 2153 MA (with an enterotoxin) were able to withstand 10 successive pressurization cycles, whereas the strain 2065 MA (with three enterotoxins) was completely inactivated after 4 cycles, with a decrease of 9.2 log CFU.mL-1. The HPP treatment did not affect none of the tested virulence factors, the mannitol fermentation ability and methicillin susceptibility of any of the strains. Moreover, none of the strains were able to recover their viability after 14 days of incubation in any of the treatment cycles. The study of the volatile exometabolome of S. aureus allowed the detection of 240 volatile organic compounds, belonging to 10 chemical families, having as main metabolic origins the degradation of amino acids, the metabolism of pyruvate and oxidative stress. It was also possible to find 10 of the most reported volatile compounds in studies concerning the volatile exometabolome of S. aureus. The detailed analysis of the volatile exometabolome allowed selecting 10 volatile compounds that have been reported more frequently in other studies concerning the volatile exometaboloma of S. aureus. The multivariate statistical analysis, allowed to distinguish the strains based on the number (or absence) of enterotoxins. The strains ATCC 6538 and 2153 MA are more similar to each other, being separated from the strain 2065 MA. This distinction is due to the latter strain has larger amounts of volatile compounds, resulting from the degradation of branched-chain amino acids, while the strain ATCC 6538 showed higher amounts of volatile compounds with origin in the degradation of methionine. In conclusion, the results showed that HPP is effective in the control of S. aureus, not allowing the development of resistance or recovery of viability after successive treatments. Although the virulence factors were not affected by HPP treatment, the enterotoxic strains were more easily inactivated than the non-enterotoxic strain. It was also concluded that the volatile exometabolome of S. aureus is quite complex and that the exometabolome analysis allows to distinguish enterotoxic strains from non-enterotoxic strains. It was possible to select a set of 10 compounds that can be potentially used as biomarkers of S. aureus.Anualmente, em todo o mundo, existem 25 milhões de casos de doenças transmitidas por alimentos fazendo com que a segurança alimentar seja um tópico de grande importância. Apesar do esforço considerável para melhorar a segurança alimentar, a incidência de intoxicações e infeções transmitidas por alimentos é ainda bastante elevada. Staphylococcus aureus é uma bactéria patogénica oportunista que possui a capacidade de crescer em vários tipos de alimentos, bem como a capacidade de produzir um grande número de fatores de virulência, incluindo enterotoxinas, as quais são responsáveis pela intoxicação alimentar estafilocócica. Esta é uma das doenças alimentares mais predominante a nível mundial. Com o aumento da procura de alimentos mais seguros, têm sido desenvolvidas novas tecnologias para a sua preservação. Entre essas tecnologias encontra-se o processamento por alta pressão (PAP), que é um método não térmico que possibilita a inativação ou o controlo de microrganismos patogénicos e de microrganismos responsáveis pela deterioração dos alimentos, ao mesmo tempo que mantém as propriedades dos alimentos. A deteção rápida e específica de microrganismos patogénicos (ou de microrganismos que podem provocar deterioração de alimentos) tornou-se cada vez mais importante na indústria alimentar. Atualmente, para detetar e identificar bactérias são utilizados métodos tradicionais baseados em testes bioquímicos e/ou serológicos e também em métodos moleculares baseados em análise de DNA ou RNA. No entanto, estes métodos são dispendiosos, demorados e/ou laboriosos. Consequentemente, é necessário desenvolver novos métodos alternativos como por exemplo, com base na metabolómica microbiana, que pode ser explorada como ferramenta para deteção de microrganismos na indústria alimentar. A metabolómica microbiana utiliza os metabolitos libertados pelos microrganismos, podendo permitir não apenas a deteção e distinção de espécies microbianas mas também das suas estirpes. Um dos objetivos deste trabalho foi avaliar a eficácia do tratamento por PAP, na inativação de estirpes não enterotóxicas e enterotóxicas de S. aureus. Deste modo, foi 1) avaliada a eficácia dos diferentes tratamentos (diversas pressões e tempos de pressurização); 2) avaliado o impacto dos tratamentos nos fatores de virulência, na capacidade de fermentação do manitol e na suscetibilidade à meticilina; 3) avaliado o desenvolvimento de resistência após vários ciclos sucessivos de PAP, e 4) avaliada a capacidade de recuperação da viabilidade após 14 dias de tratamento. Neste trabalho também se caracterizou o exometaboloma volátil de S. aureus e avaliou o seu potencial para distinguir as estirpes enterotóxicas de não enterotóxica. Assim, 1) o perfil do exometaboloma volátil de S. aureus foi caracterizado utilizando uma técnica avançada de cromatografia em fase gasosa; 2) o perfil de S. aureus foi analisado no total, avaliando a presença de compostos específicos já descritos para esta espécie bem como a sua origem metabólica; 3) aplicou-se um método de análise estatística multivariada, de forma a obter um conjunto de compostos voláteis de forma a distinguir as diferentes estirpes, nomeadamente distinguir as estirpes enterotóxicas das não enterotóxicas; e 4) este conjunto de compostos voláteis foi analisado em detalhe de forma a compreender as diferenças entre estirpes e assim justificar a sua distinção. Os resultados da inativação por PAP mostraram maior barotolerância da estirpe não enterotóxica (ATCC 6538), não sendo esta completamente inativada a 600 MPa durante 30 minutos (mantendo uma viabilidade de aproximadamente 4.0 log UFC.mL-1). Utilizando estas condições de tratamento, as duas estirpes enterotóxicas (2153 MA e 2065 MA) foram completamente inativadas. Tanto a estirpe ATCC 6538 como a estirpe 2153 MA (com uma enterotoxina) suportaram 10 ciclos de pressurização sucessivos, contrariamente à estirpe 2065 MA (com três enterotoxinas) que foi totalmente inativada ao fim de 4 ciclos, com um decréscimo de 9.2 log UFC.mL-1. O tratamento por PAP não afetou os fatores de virulência testados, nem a capacidade de fermentação do manitol e a suscetibilidade à meticilina de nenhuma das estirpes. Nenhuma das estirpes foi capaz de recuperar a viabilidade após 14 dias de incubação, em nenhum dos 10 ciclos de tratamento. O estudo do exometaboloma volátil de S. aureus permitiu detetar 240 compostos, pertencentes a 10 famílias químicas, tendo como principal origem metabólica a degradação de aminoácidos, o metabolismo do piruvato e o stresse oxidativo. A análise em detalhe do exometaboloma volátil permitiu selecionar 10 compostos voláteis que têm sidomais frequentemente reportados noutros estudos sobre o exometaboloma volátil de S. aureus. Após análise estatística multivariada, foi possível distinguir as estirpes testadas com base no número (ou na ausência) de enterotoxinas. As estirpes ATCC 6538 e 2153 MA são mais similares entre si, encontrando-se separadas da estirpe 2065 MA. Esta distinção deve-se ao facto desta última estirpe produzir maiores concentrações de compostos voláteis resultantes da degradação de aminoácidos de cadeia ramificada, enquanto a estirpe ATCC 6538 produz maiores concentrações de compostos voláteis resultantes da degradação da metionina. Em conclusão, os resultados deste estudo mostraram que o tratamento por PAP é eficaz para controlar estirpes enterotóxicas de S. aureus, não permitindo o desenvolvimento de resistência nem a recuperação da viabilidade após tratamentos sucessivos. Embora os fatores de virulência não tenham sido afetados pelo tratamento por PAP, as estirpes enterotóxicas foram mais facilmente inativadas quando comparadas com a estirpe não enterotóxica. Concluiu-se ainda que o exometaboloma volátil de S. aureus é bastante complexo e que através do estudo do exometaboloma é possível distinguir estirpes enterotóxicas de estirpes não enterotóxicas. Foi possível selecionar um conjunto de 10 compostos que poderão potencialmente vir a ser utilizados como biomarcadores da presença de S. aureus

Spacesuit Hard Upper Torso Assembly: Development Of Fit Metrics And Customized Design Frameworks

The Hard Upper Torso (HUT) of the spacesuit pressure garment is a central component of a spacesuit, enclosing the upper body and connecting with the shoulder joints, bearings, helmet, hatch, and waist-brief-hip components. The shape and positioning of the HUT and its connected components are critical for ensuring comfort, range of motion, field of view, and minimizing astronaut injury risk.This dissertation aims to build upon previous work on spacesuit sizing and develop new spacesuit fit metrics. Motion-tracking technology has been utilized to define the reach envelope and range of motion for test subjects wearing a HUT. Subjective surveys have also been conducted to evaluate suit mobility, feature alignment, indexing, and discomfort. These tools can be adapted to investigate the effects of HUT sizing, leading to the proposal of new metrics ideal for the fit and mobility of HUT based on these technologies. Additive manufacturing can be employed to create custom spacesuit hardware with minimal additional manufacturing steps. This technique enables efficient testing and benchmarking of a wide variety of HUT prototypes. With the development of fit and performance metrics, it becomes logical to utilize these metrics to design optimally sized HUT geometry. The above goals were pursued through the following activities: 1. Define two separate HUT design frameworks: The first framework will result in an optimally distributed discreet HUT sizing system, while the second will establish a framework for the rapid prediction and design of customized HUTs. 2. Investigate the subjective effect of HUT customization on HUT fitment using a subjective fit survey, demonstrating the benefits of HUT customization. 3. Explore the effect of HUT customization using human in-the-loop testing, including range of motion and reach envelope analyses, highlighting the benefits of HUT customization on suited mobility. 4. Confirm the preliminary feasibility of 3D printed HUTs through stress analysis of virtual HUT prototypes using a range of pressures, shell thicknesses, and candidate materials

Contrast-Enhanced Ultrasound for the Assessment of Response to Therapy

Accurate assessment of cancer response to therapy is important for effective treatment outcome and limiting unnecessary therapeutics. The clinical gold standard for evaluating response to therapy consists of tracking changes in volume, which works well for cytotoxic treatments such and radio or chemo therapies, which directly induce cancer cell death. However, tumor volume is ineffective for tracking response to treatments such as antiangiogenic therapies, which target the formation of new blood vessels, and often lags behind the real effect of the drugs. Studies have shown that techniques such as dynamic contrast-enhanced magnetic resonance imaging, computed tomography, and positron emission tomography perform better at predicting and assessing response to therapy than changes in volume. However, these imaging modalities are expensive, cumbersome, expose patients to ionizing radiation, and use contrast agents that can often be harmful to patients. Contrast-enhanced ultrasound (CEUS) is an imaging modality that is inexpensive, real-time, and uses microbubble contrast agents that are safe and can be used to obtain quantitative measurements of blood perfusion and levels of endothelial biomarker expression. Moreover, CEUS has been shown to assess response to therapy more accurately than tumor volume in rodent tumor models. The first hypothesis of this dissertation is that that CEUS can evaluate and track response to therapies more accurately than changes in tumor volume. The results show that CEUS can assess response to therapies that are disruptive to tumor vessel formation earlier than tumor volume. Specifically, the techniques discussed here include perfusion imaging, ultrasound molecular imaging of angiogenesis biomarkers, and acoustic angiography, which can provide metrics about microvessel morphology and density. The second hypothesis is that CEUS can be performed using phase-change contrast agents (PCCAs). PCCAs have better circulation times than conventional microbubbles and can be small enough to escape the vasculature for extravascular diagnostic imaging, and thus, may provide multiple advantages for the assessment of response to therapy. The development of techniques to perform perfusion and molecular imaging using PCCAs is described. The results show that PCCAs can be used for intravascular molecular imaging, but major modifications to the formulation are required to obtain meaningful measurements of perfusion.Doctor of Philosoph

Brain Injury

The present two volume book "Brain Injury" is distinctive in its presentation and includes a wealth of updated information on many aspects in the field of brain injury. The Book is devoted to the pathogenesis of brain injury, concepts in cerebral blood flow and metabolism, investigative approaches and monitoring of brain injured, different protective mechanisms and recovery and management approach to these individuals, functional and endocrine aspects of brain injuries, approaches to rehabilitation of brain injured and preventive aspects of traumatic brain injuries. The collective contribution from experts in brain injury research area would be successfully conveyed to the readers and readers will find this book to be a valuable guide to further develop their understanding about brain injury