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At least 289 records · Page 16

Initial Regulatory and Certification Approach for the SUSAN Electrofan Concept

New aircraft concepts and associated technologies are required to meet emerging environ-mental impact goals, while still meeting established airworthiness certification standards and regulations. The SUbsonic Single Aft eNgine (SUSAN) Electrofan is one of these concepts, utilizing a single aft-mounted engine, electrified aircraft propulsion, and an emergency backup battery. This paper explores the current certification and regulatory barriers to this novel aircraft design and the potential methods for adapting certification and regulatory requirements for the SUSAN Electrofan concept. Although some certification requirements, such as the Extended Operations regulations for continued operation after the loss of an engine, can be met with only minor changes, other requirements require modifications to the regulations or the aircraft concept for compliance. Early insight to the certification approach for the SUSAN concept, while the design is still undergoing trade space exploration, allows the development of the aircraft alongside any modifications to certification standards.

SUSAN Electrofan↗

Integrating human factors knowledge into certification: The point of view of the Internatioanal Civil Aviation Organization (ICAO)

It is appropriate here to repeat the analogy described in the introduction to this paper which is that: The consideration of human factors requirements during the design stage of advanced, new technology systems may be seen as resting over a three-legged stool. The first leg, the equipment that a system will utilize to achieve its goals, has traditionally attracted ergonomic considerations associated with equipment design, usually centered around 'knobs and dials.' Lately, this view has expanded to include the so-called other important aspect of Human Factor's study which deals with the cognitive, behaviorial and social processes of the human operators. Study in this area must be furthered. The second leg of the stool, the procedures to operate the equipment, however, has been largely unaddressed. Procedures are not inherent to equipment, but must be developed. The importance of proper human factors consideration in the design of procedures can not be overstated. Lastly, the third leg of the stool, the certification of personnel who will operate the equipment, is very much underway, but far from being complete. The real quest now, however, is to integrate these three legs into an indivisible one. Finally, and most importantly, this workshop and its topic are extremely timely in that we are at the dawn of the most ambitious development ever undertaken in international civil aviation. This would allow us the rather unique opportunity to put theory into practice in the near future by ensuring that the concepts developed and furthered by this workshop and the follow-up are implemented in the design and certification of the ICAO future CNS/ATM systems described earlier in this paper. Now is the time to incorporate human factors requirements during the certification processes of these systems. This might act as a test to the feasibility of these ideas. Such endeavors represent a challenge for the research, engineering, training, operational and regulatory communities. But there is certainly more to be gained by attempting to meet the challenge rather than refraining from progress by decrying the difficulties involved.

Maurino, Daniel↗

Maintaining safety and high performance on shiftwork

This review of the shiftwork area focuses on aspects of safety and productivity. It discusses the situations in which shiftworker performance is critical, the types of problem that can develop and the reasons why shiftworker performance can be impaired. The review ends with a discnssion of the various advantages and disadvantages of several shift rotation systems, and of other possible solutions to the problem.

Review↗

Overview of spaceflight immunology studies

The effects of spaceflight and analogues of spaceflight are discussed here and in nine accompanying articles. In this summary we present spaceflight studies with human subjects, animal subjects, and cell cultures and we review ground-based systems used to model the observed effects of spaceflight on the immune system. Human paradigms include bed rest, academic or psychological stress, physical stress, hypobaric or high altitude stress, and confinement. Animal models include antiorthostatic and orthostatic suspension, hypobarism, and confinement. The ten manuscripts in this collection were selected to provide a summary that should give the reader an overview of the various activities of spaceflight immunology researchers throughout the history of space travel. This manuscript identifies the major contributors to the study of spaceflight immunology, explains what types of studies have been conducted, and how they have changed over the years. Also presented is a discussion of the unusual limitations associated with spaceflight research and the efforts to develop appropriate ground-based surrogate model systems. Specific details, data, and mechanistic speculations will be held to a minimum, because they will be discussed in depth in the other articles in the collection.

NASA Discipline Number 18-10↗

HRP's Healthcare Spin-Offs Through Computational Modeling and Simulation Practice Methodologies

Spaceflight missions expose astronauts to novel operational and environmental conditions that pose health risks that are currently not well understood, and perhaps unanticipated. Furthermore, given the limited number of humans that have flown in long duration missions and beyond low Earth-orbit, the amount of research and clinical data necessary to predict and mitigate these health and performance risks are limited. Consequently, NASA's Human Research Program (HRP) conducts research and develops advanced methods and tools to predict, assess, and mitigate potential hazards to the health of astronauts. In this light, NASA has explored the possibility of leveraging computational modeling since the 1970s as a means to elucidate the physiologic risks of spaceflight and develop countermeasures. Since that time, substantial progress has been realized in this arena through a number of HRP funded activates such as the Digital Astronaut Project (DAP) and the Integrated Medical Model (IMM). Much of this success can be attributed to HRP's endeavor to establish rigorous verification, validation, and credibility (VV&C) processes that ensure computational models and simulations (M&S) are sufficiently credible to address issues within their intended scope. This presentation summarizes HRP's activities in credibility of modeling and simulation, in particular through its outreach to the community of modeling and simulation practitioners. METHODS: The HRP requires all M&S that can have moderate to high impact on crew health or mission success must be vetted in accordance to NASA Standard for Models and Simulations, NASA-STD-7009 (7009) [5]. As this standard mostly focuses on engineering systems, the IMM and DAP have invested substantial efforts to adapt the processes established in this standard for their application to biological M&S, which is more prevalent in human health and performance (HHP) and space biomedical research and operations [6,7]. These methods have also generated substantial interest by the broader medical community though institutions like the National Institutes of Health (NIH) and the Food and Drug Administration (FDA) to develop similar standards and guidelines applicable to the larger medical operations and research community. DISCUSSION: Similar to NASA, many leading government agencies, health institutions and medical product developers around the world are recognizing the potential of computational M&S to support clinical research and decision making. In this light, substantial investments are being made in computational medicine and notable discoveries are being realized [8]. However, there is a lack of broadly applicable practice guidance for the development and implementation of M&S in clinical care and research in a manner that instills confidence among medical practitioners and biological researchers [9,10]. In this presentation, we will give an overview on how HRP is working with the NIH's Interagency Modeling and Analysis Group (IMAG), the FDA and the American Society of Mechanical Engineers (ASME) to leverage NASA's biomedical VV&C processes to establish a new regulatory standard for Verification and Validation in Computational Modeling of Medical Devices, and Guidelines for Credible Practice of Computational Modeling and Simulation in Healthcare.

Mulugeta, Lealem↗

RNA-binding proteins in plants: the tip of an iceberg?

RNA-binding proteins, which are involved in the synthesis, processing, transport, translation, and degradation of RNA, are emerging as important, often multifunctional, cellular regulatory proteins. Although relatively few RNA-binding proteins have been studied in plants, they are being identified with increasing frequency, both genetically and biochemically. RNA-binding proteins that regulate chloroplast mRNA stability and translation in response to light and that have been elegantly analyzed in Clamydomonas reinhardtii have counterparts with similar functions in higher plants. Several recent reports describe mutations in genes encoding RNA-binding proteins that affect plant development and hormone signaling.

Review↗

Environmentally regulated aerospace coatings

Aerospace coatings represent a complex technology which must meet stringent performance requirements in the protection of aerospace vehicles. Topcoats and primers are used, primarily, to protect the structural elements of the air vehicle from exposure to and subsequent degradation by environmental elements. There are also many coatings which perform special functions, i.e., chafing resistance, rain erosion resistance, radiation and electric effects, fuel tank coatings, maskants, wire and fastener coatings. The scheduled promulgation of federal environmental regulations for aerospace manufacture and rework materials and processes will regulate the emissions of photochemically reactive precursors to smog and air toxics. Aerospace organizations will be required to identify, qualify and implement less polluting materials. The elimination of ozone depleting chemicals (ODC's) and implementation of pollution prevention requirements are added constraints which must be addressed concurrently. The broad categories of operations affected are the manufacture, operation, maintenance, and repair of military, commercial, general aviation, and space vehicles. The federal aerospace regulations were developed around the precept that technology had to be available to support the reduction of organic and air toxic emissions, i.e., the regulations cannot be technology forcing. In many cases, the regulations which are currently in effect in the South Coast Air Quality Management District (SCAQMD), located in Southern California, were used as the baseline for the federal regulations. This paper addresses strategies used by Southern California aerospace organizations to cope with these regulatory impacts on aerospace productions programs. All of these regulatory changes are scheduled for implementation in 1993 and 1994, with varying compliance dates established.

Morris, Virginia L.↗

Explicate '78: Uncovering the Implicit Assurance Case in DO-178C

For about two decades, compliance with Software Considerations in Airborne Systems and Equipment Certification (DO-178B/ED-12B) has been the primary means for receiving regulatory approval for using software on commercial airplanes. A new edition of the standard, DO-178C/ED-12C, was published in December 2011, and recognized by regulatory bodies in 2013. The purpose remains unchanged: to provide guidance 'for the production of software for airborne systems and equipment that performs its intended function with a level of confidence in safety that complies with airworthiness requirements.' The text of the guidance does not directly explain how its collection of objectives contributes to achieving this purpose; thus, the assurance case for the document is implicit. This paper presents an explicit assurance case developed as part of research jointly sponsored by the Federal Aviation Administration and the National Aeronautics and Space Administration.

Holloway, C. Michael↗

Smart medical systems with application to nutrition and fitness in space

Smart medical systems are being developed to allow medical treatments to address alterations in chemical and physiologic status in real time. In a smart medical system, sensor arrays assess subject status, which is interpreted by computer processors that analyze multiple inputs and recommend treatment interventions. The response of the subject to the treatment is again assessed by the sensor arrays, thus closing the loop. An early form of "smart medicine" has been practiced in space to assess nutrition. Nutrient levels are assessed with food frequency questionnaires, which are interpreted by flight surgeons to recommend inflight alterations in diet. In the future, sensor arrays will directly probe body chemistry. Near-infrared spectroscopy can be used to non-invasively measure several blood and tissue parameters that are important in the assessment of nutrition and fitness. In particular, this technology can be used to measure blood hematocrit and interstitial fluid pH. The non-invasive measurement of interstitial pH is discussed as a surrogate for blood lactate measurement for the development and real-time assessment of exercise protocols in space. Earth-based application of these sensors is also described.

NASA Discipline Life Sciences Technologies↗

Use of animal models for space flight physiology studies, with special focus on the immune system

Animal models have been used to study the effects of space flight on physiological systems. The animal models have been used because of the limited availability of human subjects for studies to be carried out in space as well as because of the need to carry out experiments requiring samples and experimental conditions that cannot be performed using humans. Experiments have been carried out in space using a variety of species, and included developmental biology studies. These species included rats, mice, non-human primates, fish, invertebrates, amphibians and insects. The species were chosen because they best fit the experimental conditions required for the experiments. Experiments with animals have also been carried out utilizing ground-based models that simulate some of the effects of exposure to space flight conditions. Most of the animal studies have generated results that parallel the effects of space flight on human physiological systems. Systems studied have included the neurovestibular system, the musculoskeletal system, the immune system, the neurological system, the hematological system, and the cardiovascular system. Hindlimb unloading, a ground-based model of some of the effects of space flight on the immune system, has been used to study the effects of space flight conditions on physiological parameters. For the immune system, exposure to hindlimb unloading has been shown to results in alterations of the immune system similar to those observed after space flight. This has permitted the development of experiments that demonstrated compromised resistance to infection in rodents maintained in the hindlimb unloading model as well as the beginning of studies to develop countermeasures to ameliorate or prevent such occurrences. Although there are limitations to the use of animal models for the effects of space flight on physiological systems, the animal models should prove very valuable in designing countermeasures for exploration class missions of the future.

Review↗

The Civil Aviation Sector in Lebanon: Institutional Reforms - Part 1

Civil aviation is one of the key contributors to a successful economic system. This has been recognized within Lebanon, which is undertaking developing a new civil aviation strategy encompassing a program of organizational reform, coordinated internationally, to meet the challenges of the new century. Such strategy is vital, as it will provide a coherent vision for the sector, compliment the extensive investments deployed by Lebanon in its aviation infrastructure, and guide future planning and investments. The proposed Civil Aviation Strategy for Lebanon has two major components: (1) institutional reform aiming at creating effective overall legal and regulatory frameworks in-line with current international best practice; and (2) implementation of liberalization measures and open skies policy. This paper aims to: (1) present Lebanon's current institutional arrangements; (2) review the institutional arrangements in key select countries (in order to define current trends in best institutional practice); (3) discuss the proposed institutional reform (which are at the basis of Lebanon's Draft Civil Aviation Reform Law) while showing that they conform with the identified best institutional trends; and (4) outline an implementation plan. The Draft Law has been approved by the Council of Ministers and now awaits Parliamentary endorsement.

Baaj, M. Hadi↗

Air Quality Data Fusion with Sensors, Satellites, and Models

Global forecasting models, satellite remote sensing, and ground-based regulatory and low-cost monitors all have strengths and weaknesses with respect to providing locally relevant information about air quality. This presentation will give a brief overview of these data sources and then discuss a method for combining them via data fusion to support near-real-time air quality estimation and forecasting at sub-city scales. The basic idea behind the approach will be summarized, followed by an update on recent developments towards creating an operational system using Google Earth Engine and on quantifying uncertainties related to data fusion outputs.

Carl Malings↗

Baroreflex dysfunction induced by microgravity: potential relevance to postflight orthostatic intolerance

Microgravity imposes adaptive changes in the human body. This review focuses on the changes in baroreflex function produced by actual spaceflight, or by experimental models that simulate microgravity, e.g., bed rest. We will analyze separately studies involving baroreflexes arising from carotid sinus and aortic arch afferents ("high-pressure baroreceptors"), and cardiopulmonary afferents ("low-pressure receptors"). Studies from unrelated laboratories using different techniques have concluded that actual or simulated exposure to microgravity reduces baroreflex function arising from carotid sinus afferents ("carotic-cardiac baroreflex"). The techniques used to study the carotid-cardiac baroreflex, using neck suction and compression to simulate changes in blood pressure, have been extensively validated. In contrast, it is more difficult to selectively study aortic arch or cardiopulmonary baroreceptors. Nonetheless, studies that have examined these baroreceptors suggest that microgravity produces the opposite effect, ie, an increase in the gain of aortic arch and cardiopulmonary baroreflexes. Furthermore, most studies have focus on instantaneous changes in heart rate, which almost exclusively examines the vagal limb of the baroreflex. In comparison, there is limited information about the effect of microgravity on sympathetic function. A substantial proportion of subjects exposed to microgravity develop transient orthostatic intolerance. It has been proposed that alterations in baroreflex function play a role in the orthostatic intolerance induced by microgravity. The evidence in favor and against this hypothesis is reviewed.

manned↗

Beta-adrenoceptor dysfunction after inhibition of NO synthesis

G(s) protein-coupled beta-adrenoceptors rapidly desensitize on exposure to agonists in reconstituted membrane preparations, whereas rapid tachyphylaxis to beta-adrenoceptor-mediated vasodilation does not readily occur in vivo. This study examined the possibility that endothelium-derived nitrosyl factors prevent the rapid desensitization of beta-adrenoceptors in the vascular smooth muscle of resistance arteries in pentobarbital-anesthetized rats. The fall in mean arterial blood pressure and in hindquarter vascular resistance produced by the beta-adrenoceptor agonist isoproterenol (ISO, 0.1 to 10 microg/kg IV) was slightly but significantly smaller in rats treated with the NO synthase inhibitor N:(G)-nitro-L-arginine methyl ester (L-NAME, 100 micromol/kg IV) than in saline-treated rats. The ISO-induced fall in mesenteric resistance was similar in L-NAME-treated and in saline-treated rats. The fall in hindquarter vascular resistance and in mesenteric resistance produced by ISO (8 x 10 microg/kg IV) was subject to tachyphylaxis on repeated injection in rats treated with L-NAME (100 micromol/kg IV) but not in rats treated with saline. Injections of L-S:-nitrosocysteine (1200 nmol/kg IV), a lipophobic S:-nitrosothiol, before each injection of ISO (10 microg/kg IV) prevented tachyphylaxis to ISO in L-NAME-treated rats. The vasodilator effects of ISO (0.1 to 10 microg/kg IV) in L-NAME-treated rats that received 8 injections of ISO (10 microg/kg IV) were markedly smaller than in L-NAME-treated rats that received 8 injections of saline. These results indicate that (1) the vasodilator actions of ISO in pentobarbital-anesthetized rats only minimally involve the release of endothelium-derived nitrosyl factors, (2) the effects of ISO are subject to development of tachyphylaxis in L-NAME-treated rats, and (3) tachyphylaxis to ISO is prevented by L-S:-nitrosocysteine. These findings suggest that endothelium-derived nitrosyl factors may prevent desensitization of beta-adrenoceptors in vivo.

NASA Discipline Regulatory Physiology↗

Calcium metabolism before, during, and after a 3-mo spaceflight: kinetic and biochemical changes

The loss of bone during spaceflight is considered a physiological obstacle for the exploration of other planets. This report of calcium metabolism before, during, and after long-duration spaceflight extends results from Skylab missions in the 1970s. Biochemical and endocrine indexes of calcium and bone metabolism were measured together with calcium absorption, excretion, and bone turnover using stable isotopes. Studies were conducted before, during, and after flight in three male subjects. Subjects varied in physical activity, yet all lost weight during flight. During flight, calcium intake and absorption decreased up to 50%, urinary calcium excretion increased up to 50%, and bone resorption (determined by kinetics or bone markers) increased by over 50%. Osteocalcin and bone-specific alkaline phosphatase, markers of bone formation, increased after flight. Subjects lost approximately 250 mg bone calcium per day during flight and regained bone calcium at a slower rate of approximately 100 mg/day for up to 3 mo after landing. Further studies are required to determine the time course of changes in calcium homeostasis during flight to develop and assess countermeasures against flight-induced bone loss.

NASA Discipline Regulatory Physiology↗

Predicting sudden cardiac death from T wave alternans of the surface electrocardiogram: promise and pitfalls

Sudden cardiac death remains a preeminent public health problem. Despite advances in preventative treatment for patients known to be at risk, to date we have been able to identify, and thus treat, only a small minority of these patients. Therefore, there is a major need to develop noninvasive diagnostic technologies to identify patients at risk. Recent studies have demonstrated that measurement of microvolt-level T wave alternans is a promising technique for the accurate identification of patients at risk for ventricular arrhythmias and sudden cardiac death. In this article, we review the clinical data establishing the relationship between microvolt T wave alternans and susceptibility to ventricular arrhythmias. We also review the methods and technology that have been developed to measure microvolt levels of T wave alternans noninvasively in broad populations of ambulatory patients. In particular, we examine techniques that permit the accurate measurement of T wave alternans during exercise stress testing.

Review, Tutorial↗

Final Report - Regulatory Considerations for Adaptive Systems

This report documents the findings of a preliminary research study into new approaches to the software design assurance of adaptive systems. We suggest a methodology to overcome the software validation and verification difficulties posed by the underlying assumption of non-adaptive software in the requirementsbased- testing verification methods in RTCA/DO-178B and C. An analysis of the relevant RTCA/DO-178B and C objectives is presented showing the reasons for the difficulties that arise in showing satisfaction of the objectives and suggested additional means by which they could be satisfied. We suggest that the software design assurance problem for adaptive systems is principally one of developing correct and complete high level requirements and system level constraints that define the necessary system functional and safety properties to assure the safe use of adaptive systems. We show how analytical techniques such as model based design, mathematical modeling and formal or formal-like methods can be used to both validate the high level functional and safety requirements, establish necessary constraints and provide the verification evidence for the satisfaction of requirements and constraints that supplements conventional testing. Finally the report identifies the follow-on research topics needed to implement this methodology.

Wilkinson, Chris↗

Development and characterization of Histoplasma capsulatum-reactive murine T-cell lines and clones

Several Histoplasma capsulatum-reactive murine cloned T-cell lines (TCLs) were isolated from spleens of C57BL/6 mice immunized with viable H. capsulatum yeast cells, using the methodology of Kimoto and Fathman (1980). These T-cells were characterized phenotypically as Thy-1.2(+) Lyt-1(+) L3T4(+) Lyt-2(-), that is, as the helper/inducer phenotype. The cloned T cells proliferate in response to histoplasmin and, in some cases, to heterologous fungal anigens. Upon injection of mice with the antigen, the T-cells mediate local delayed-type hypersensitivity responses and, after stimulation, release regulatory lymphokines.

Deepe, George S., Jr.↗