122 research outputs found

    Shuttle Shortfalls and Lessons Learned for the Sustainment of Human Space Exploration

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    Much debate and national soul searching has taken place over the value of the Space Shuttle which first flew in 1981 and which is currently scheduled to be retired in 2010. Originally developed post-Saturn Apollo to emphasize affordability and safety, the reusable Space Shuttle instead came to be perceived as economically unsustainable and lacking the technology maturity to assure safe, routine access to low earth orbit (LEO). After the loss of two crews, aboard Challenger and Columbia, followed by the decision to retire the system in 2010, it is critical that this three decades worth of human space flight experience be well understood. Understanding of the past is imperative to further those goals for which the Space Shuttle was a stepping-stone in the advancement of knowledge. There was significant reduction in life cycle costs between the Saturn Apollo and the Space Shuttle. However, the advancement in life cycle cost reduction from Saturn Apollo to the Space Shuttle fell far short of its goal. This paper will explore the reasons for this shortfall. Shortfalls and lessons learned can be categorized as related to design factors, at the architecture, element and sub-system levels, as well as to programmatic factors, in terms of goals, requirements, management and organization. Additionally, no review of the Space Shuttle program and attempt to take away key lessons would be complete without a strategic review. That is, how do national space goals drive future space transportation development strategies? The lessons of the Space Shuttle are invaluable in all respects - technical, as in design, program-wise, as in organizational approach and goal setting, and strategically, within the context of the generational march toward an expanded human presence in space. Beyond lessons though (and the innumerable papers, anecdotes and opinions published on this topic) this paper traces tangible, achievable steps, derived from the Space Shuttle program experience, that must be a part of any 2l century initiatives furthering a growing human presence beyond earth

    The Need for Technology Maturity of Any Advanced Capability to Achieve Better Life Cycle Cost (LCC)

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    Programs such as space transportation systems are developed and deployed only rarely, and they have long development schedules and large development and life cycle costs (LCC). They have not historically had their LCC predicted well and have only had an effort to control the DDT&E phase of the programs. One of the factors driving the predictability, and thus control, of the LCC of a program is the maturity of the technologies incorporated in the program. If the technologies incorporated are less mature (as measured by their Technology Readiness Level - TRL), then the LCC not only increases but the degree of increase is difficult to predict. Consequently, new programs avoid incorporating technologies unless they are quite mature, generally TRL greater than or equal to 7 (system prototype demonstrated in a space environment) to allow better predictability of the DDT&E phase costs unless there is no alternative. On the other hand, technology development programs rarely develop technologies beyond TRL 6 (system/subsystem model or prototype demonstrated in a relevant environment). Currently the lack of development funds beyond TRL 6 and the major funding required for full scale development leave little or no funding available to prototype TRL 6 concepts so that hardware would be in the ready mode for safe, reliable and cost effective incorporation. The net effect is that each new program either incorporates little new technology or has longer development schedules and costs, and higher LCC, than planned. This paper presents methods to ensure that advanced technologies are incorporated into future programs while providing a greater accuracy of predicting their LCC. One method is having a dedicated organization to develop X-series vehicles or separate prototypes carried on other vehicles. The question of whether such an organization should be independent of NASA and/or have an independent funding source is discussed. Other methods are also discussed. How to make the choice of which technologies to pursue to the prototype level is also discussed since, to achieve better LCC, first the selection of the appropriate technologies

    Propulsion System Choices and Their Implications

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    In defining a space vehicle architecture, the propulsion system and related subsystem choices will have a major influence on achieving the goals and objectives desired. There are many alternatives and the choices made must produce a system that meets the performance requirements, but at the same time also provide the greatest opportunity of reaching all of the required objectives. Recognizing the above, the SPST Functional Requirements subteam has drawn on the knowledge, expertise, and experience of its members, to develop insight that wiIJ effectively aid the architectural concept developer in making the appropriate choices consistent with the architecture goals. This data not only identifies many selected choices, but also, more importantly, presents the collective assessment of this subteam on the "pros" and the "cons" of these choices. The propulsion system choices with their pros and cons are presented in five major groups. A. System Integration Approach. Focused on the requirement for safety, reliability, dependability, maintainability, and low cost. B. Non-Chemical Propulsion. Focused on choice of propulsion type. C. Chemical Propulsion. Focused on propellant choice implications. D. Functional Integration. Focused on the degree of integration of the many propulsive and closely associated functions, and on the choice of the engine combustion power cycle. E. Thermal Management. Focused on propellant tank insulation and integration. Each of these groups is further broken down into subgroups, and at that level the consensus pros and cons are presented. The intended use of this paper is to provide a resource of focused material for architectural concept developers to use in designing new advanced systems including college design classes. It is also a possible source of input material for developing a model for designing and analyzing advanced concepts to help identify focused technology needs and their priorities

    DNA analysis of breast tumour fine needle aspirates using flow cytometry.

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    Cellular DNA was analysed by flow cytometry in fine needles aspirates (FNA) from both benign and malignant breast lesions in order to determine the feasibility of flow cytometric analysis. In 22 of 26 (84%) benign and 69 of 74 (93%) malignant aspirates, sufficient cells were present to produce good quality DNA histograms. DNA in all 22 benign lesions was diploid. In contrast, of the 69 cancers with sufficient cells for analysis, 40.6% had a diploid DNA content alone, whilst 59.4% had an additional DNA aneuploid line. These results indicate that the majority of FNAs provide sufficient material for flow cytometric analysis of DNA profiles. Such aspirates taken in a sequential manner may also prove to be an ideal method of studying tumour response to therapy

    Concepts for Life Cycle Cost Control Required to Achieve Space Transportation Affordability and Sustainability

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    Cost control must be implemented through the establishment of requirements and controlled continually by managing to these requirements. Cost control of the non-recurring side of life cycle cost has traditionally been implemented in both commercial and government programs. The government uses the budget process to implement this control. The commercial approach is to use a similar process of allocating the non-recurring cost to major elements of the program. This type of control generally manages through a work breakdown structure (WBS) by defining the major elements of the program. If the cost control is to be applied across the entire program life cycle cost (LCC), the approach must be addressed very differently. A functional breakdown structure (FBS) is defined and recommended. Use of a FBS provides the visibifity to allow the choice of an integrated solution reducing the cost of providing many different elements of like function. The different functional solutions that drive the hardware logistics, quantity of documentation, operational labor, reliability and maintainability balance, and total integration of the entire system from DDT&E through the life of the program must be fully defined, compared, and final decisions made among these competing solutions. The major drivers of recurring cost have been identified and are presented and discussed. The LCC requirements must be established and flowed down to provide control of LCC. This LCC control will require a structured rigid process similar to the one traditionally used to control weight/performance for space transportation systems throughout the entire program. It has been demonstrated over the last 30 years that without a firm requirement and methodically structured cost control, it is unlikely that affordable and sustainable space transportation system LCC will be achieved

    Advanced Space Transportation Concepts and Propulsion Technologies for a New Delivery Paradigm

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    This paper describes Advanced Space Transportation Concepts and Propulsion Technologies for a New Delivery Paradigm. It builds on the work of the previous paper "Approach to an Affordable and Productive Space Transportation System". The scope includes both flight and ground system elements, and focuses on their compatibility and capability to achieve a technical solution that is operationally productive and also affordable. A clear and revolutionary approach, including advanced propulsion systems (advanced LOX rich booster engine concept having independent LOX and fuel cooling systems, thrust augmentation with LOX rich boost and fuel rich operation at altitude), improved vehicle concepts (autogeneous pressurization, turbo alternator for electric power during ascent, hot gases to purge system and keep moisture out), and ground delivery systems, was examined. Previous papers by the authors and other members of the Space Propulsion Synergy Team (SPST) focused on space flight system engineering methods, along with operationally efficient propulsion system concepts and technologies. This paper continues the previous work by exploring the propulsion technology aspects in more depth and how they may enable the vehicle designs from the previous paper. Subsequent papers will explore the vehicle design, the ground support system, and the operations aspects of the new delivery paradigm in greater detail

    Cochrane rehabilitation: 2020 Annual report

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    during its fourth year of existence, cochrane rehabilitation went on to promote evidence-informed health decision-making in rehabilitation. in 2020, the outbreak of the coVid-19 pandemic has made it necessary to alter priorities. in these challenging times, cochrane rehabilitation has firstly changed its internal organisation and established a new relevant project in line with pandemic needs: the REH-COVER (Rehabilitation – coVid-19 evidence-based response) action. the aim was to focus on the timely collection, review and dissemination of summarised and synthesised evidence relating to COVID-19 and rehabilitation. Cochrane Rehabilitation REH-COVER action has included in 2020 five main initiatives: 1) rapid living systematic reviews on rehabilitation and coVid-19; 2) interactive living evidence map on rehabilitation and coVid-19; 3) definition of the research topics on “rehabilitation and COVID-19” in collaboration with the World Health Organization (WHO) rehabilitation programme; 4) Cochrane Library special collection on Coronavirus (COVID-19) rehabilitation; and 5) collaboration with COVID-END for the topics “rehabilitation” and “disability.” Furthermore, we are still carrying on five different special projects: Be4rehab; RCTRACK; definition of rehabilitation for research purposes; ebook project; and a prioritization exercise for Cochrane Reviews production. The Review Working Area continued to identify and “tag” the rehabilitation-relevant reviews published in the cochrane library; the publication Working area went on to publish Cochrane Corners, working more closely with the Cochrane Review Groups (CRGs) and Cochrane Networks, particularly with Cochrane Musculoskeletal, oral, skin and sensory Network; the Education Working area, the most damaged in 2020, tried to continue performing educational activities such as workshops in different online meetings; the Methodology Working area organized the third and fourth cochrane Rehabilitation Methodological (CRM) meetings respectively in Milan and Orlando; the Communication Working Area spread rehabilitation evidences through different channels and translated the contents in different languages

    Interventions to increase engagement with rehabilitation in adults with acquired brain injury: A systematic review

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    Rehabilitation in adults with acquired brain injury is often hampered by a lack of client engagement with the rehabilitation process, leading to frustration, withdrawal of services and poorer recovery. Motivation, apathy and awareness are potential mechanisms underlying engagement, but few studies have suggested potential intervention techniques. A systematic review of the literature was carried out to identify and evaluate interventions designed to increase rehabilitation engagement in adults with acquired brain injury. Database searches used the following terms: rehabilitation, brain injury, and compliance/engagement/adherence in PsychInfo, Medline, Cinahl, Embase, AMED, Web of Knowledge, PsycBite, Cochrane clinical trials, and clinicaltrials.org. Hand searches were conducted of reference lists and relevant journals. Fifteen studies were included in the review. Intervention techniques fell into two broad categories: behavioural modification techniques and cognitive/meta-cognitive skills. Contingent reward techniques were most effective at increasing adherence and compliance, while interventions enabling clients' active participation in rehabilitation appeared to increase engagement and motivation. The review highlighted methodological and measurement inconsistencies in the field and suggested that interventions should be tailored to clients' abilities and circumstances

    Towards a New Definition of Return-to-Work Outcomes in Common Mental Disorders from a Multi-Stakeholder Perspective

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    Objectives: To examine the perspectives of key stakeholders involved in the return-to-work (RTW) process regarding the definition of successful RTW outcome after sickness absence related to common mental disorders (CMD's). Methods: A mixed-method design was used: First, we used qualitative methods (focus groups, interviews) to identify a broad range of criteria important for the definition of successful RTW (N = 57). Criteria were grouped into content-related clusters. Second, we used a quantitative approach (online questionnaire) to identify, among a larger stakeholder sample (N = 178), the clusters and criteria most important for successful RTW. Results: A total of 11 clusters, consisting of 52 unique criteria, were identified. In defining successful RTW, supervisors and occupational physicians regarded "Sustainability'' and "At-work functioning" most important, while employees regarded "Sustainability," "Job satisfaction," "Work-home balance,'' and " Mental Functioning" most important. Despite agreement on the importance of certain criteria, considerable differences among stakeholders were observed. Conclusions: Key stakeholders vary in the aspects and criteria they regard as important when defining successful RTW after CMD-related sickness absence. Current definitions of RTW outcomes used in scientific research may not accurately reflect these key stakeholder perspectives. Future studies should be more aware of the perspective from which they aim to evaluate the effectiveness of a RTW intervention, and define their RTW outcomes accordingly
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