Sample records for study design limitations
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The Single-Group, Pre- and Posttest Design in Nursing Education Research: It's Time to Move on.
Spurlock, Darrell R
2018-02-01
Studying the effectiveness of educational interventions is centrally important to building the science of nursing education. Yet, the design most commonly used in the study of nursing education interventions-the single-group, preand posttest design-provides limited evidence to support claims of intervention effectiveness. In this Methodology Corner installment, the limitations of the single-group, preand posttest design are outlined and a review of the requirements for establishing stronger arguments for causality is presented. To overcome the limitations of single-group, preand posttest designs, nursing education researchers are encouraged to employ study designs and procedures that can significantly strengthen researchers' claims of intervention effectiveness. [J Nurs Educ. 2018;57(2):69-71.]. Copyright 2018, SLACK Incorporated.
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Sylvia, Louisa G.; Reilly-Harrington, Noreen A.; Leon, Andrew C.; Kansky, Christine I.; Ketter, Terence A.; Calabrese, Joseph R.; Thase, Michael E.; Bowden, Charles L.; Friedman, Edward S.; Ostacher, Michael J.; Iosifescu, Dan V.; Severe, Joanne; Nierenberg, Andrew A.
2013-01-01
Background High attrition rates which occur frequently in longitudinal clinical trials of interventions for bipolar disorder limit the interpretation of results. Purpose The aim of this article is to present design approaches that limited attrition in the Lithium Use for Bipolar Disorder (LiTMUS) Study. Methods LiTMUS was a 6-month randomized, longitudinal multi-site comparative effectiveness trial that examined bipolar participants who were at least mildly ill. Participants were randomized to either low to moderate doses of lithium or no lithium, in addition to other treatments needed for mood stabilization administered in a guideline-informed, empirically supported, and personalized fashion (N=283). Results Components of the study design that may have contributed to the low attrition rate of the study included use of: (1) an intent-to-treat design; (2) a randomized adjunctive single-blind design; (3) participant reimbursement; (4) intent-to-attend the next study visit (includes a discussion of attendance obstacles when intention is low); (5) quality care with limited participant burden; and (6) target windows for study visits. Limitations Site differences and the effectiveness and tolerability data have not been analyzed yet. Conclusions These components of the LiTMUS study design may have reduced the probability of attrition which would inform the design of future randomized clinical effectiveness trials. PMID:22076437
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NASA Technical Reports Server (NTRS)
Morscher, Gregory N.; Pujar, Vijay V.
2008-01-01
In-plane tensile stress-strain, tensile creep, and after-creep retained tensile properties of melt-infiltrated SiC-SiC composites reinforced with different fiber types were evaluated with an emphasis on obtaining simple or first-order microstructural design guidelines for these in-plane mechanical properties. Using the mini-matrix approach to model stress-strain behavior and the results of this study, three basic general design criteria for stress and strain limits are formulated, namely a design stress limit, a design total strain limit, and an after-creep design retained strength limit. It is shown that these criteria can be useful for designing components for high temperature applications.
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Limitations of the method of characteristics when applied to axisymmetric hypersonic nozzle design
NASA Technical Reports Server (NTRS)
Edwards, Anne C.; Perkins, John N.; Benton, James R.
1990-01-01
A design study of axisymmetric hypersonic wind tunnel nozzles was initiated by NASA Langley Research Center with the objective of improving the flow quality of their ground test facilities. Nozzles for Mach 6 air, Mach 13.5 nitrogen, and Mach 17 nitrogen were designed using the Method of Characteristics/Boundary Layer (MOC/BL) approach and were analyzed with a Navier-Stokes solver. Results of the analysis agreed well with design for the Mach 6 case, but revealed oblique shock waves of increasing strength originating from near the inflection point of the Mach 13.5 and Mach 17 nozzles. The findings indicate that the MOC/BL design method has a fundamental limitation that occurs at some Mach number between 6 an 13.5. In order to define the limitation more exactly and attempt to discover the cause, a parametric study of hypersonic ideal air nozzles designed with the current MOC/BL method was done. Results of this study indicate that, while stagnations conditions have a moderate affect on the upper limit of the method, the method fails at Mach numbers above 8.0.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Yao, Shuhuai; Bakajin, Olgica
2007-08-01
Using a microfluidic laminar flow mixer designed for studies of protein folding kinetics, we demonstrate a mixing time of 1 +/- 1 micros with sample consumption on the order of femtomoles. We recognize two limitations of previously proposed designs: (1) size and shape of the mixing region, which limits mixing uniformity and (2) the formation of Dean vortices at high flow rates, which limits the mixing time. We address these limitations by using a narrow shape-optimized nozzle and by reducing the bend of the side channel streamlines. The final design, which combines both of these features, achieves the best performance.more » We quantified the mixing performance of the different designs by numerical simulation of coupled Navier-Stokes and convection-diffusion equations and experiments using fluorescence resonance energy-transfer (FRET)-labeled DNA.« less
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Schildmann, Eva K; Higginson, Irene J
2011-06-01
Despite evidence of negative psychological sequelae and unmet needs, there are few evaluated interventions for informal caregivers in cancer and palliative care. The aim of this article is to debate the strengths and limitations of randomized controlled trials (RCTs) and other designs that can be used to evaluate the effectiveness of these interventions. Psycho-educational interventions are used as example for this debate article, as a number of studies of various designs evaluating this type of intervention have been published. Systematic searching in Medline and the bibliography of a relevant systematic review identified five RCTs, one pre-test/post-test study with a control group and six one-group pre-test/post-test studies of psycho-educational interventions for caregivers. The methodological strengths and weaknesses were assessed. RCTs are seen as the gold standard, but can have important limitations in the context of carer intervention research, including biased recruitment and low generalizability, problems with blinding and attrition. Pre-test/post-test studies with a control group may be more feasible and more generalizable. Their crucial limitation is selection bias. Before-after studies are compromised by additional specific biases and therefore are the weakest of all discussed designs. After analysing the strengths and weaknesses of the mentioned study designs, this paper presents strategies to address the limitations of RCTs evaluating psycho-educational interventions for carers in cancer or palliative care. © The Author(s) 2011
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The Development of Preschoolers' Living Kinds Concept: A Longitudinal Study
ERIC Educational Resources Information Center
Margett-Jordan, Tessa; Falcon, Rachael G.; Witherington, David C.
2017-01-01
Given limitations in the integrative scope of past research, basic questions about the organization and development of preschoolers' living kinds concept remain open to debate. This study was designed to address past limitations through use of a longitudinal design, extensive stimulus set, and alternate indices of understanding. Thirty-five…
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Limit states and reliability-based pipeline design. Final report
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zimmerman, T.J.E.; Chen, Q.; Pandey, M.D.
1997-06-01
This report provides the results of a study to develop limit states design (LSD) procedures for pipelines. Limit states design, also known as load and resistance factor design (LRFD), provides a unified approach to dealing with all relevant failure modes combinations of concern. It explicitly accounts for the uncertainties that naturally occur in the determination of the loads which act on a pipeline and in the resistance of the pipe to failure. The load and resistance factors used are based on reliability considerations; however, the designer is not faced with carrying out probabilistic calculations. This work is done during developmentmore » and periodic updating of the LSD document. This report provides background information concerning limits states and reliability-based design (Section 2), gives the limit states design procedures that were developed (Section 3) and provides results of the reliability analyses that were undertaken in order to partially calibrate the LSD method (Section 4). An appendix contains LSD design examples in order to demonstrate use of the method. Section 3, Limit States Design has been written in the format of a recommended practice. It has been structured so that, in future, it can easily be converted to a limit states design code format. Throughout the report, figures and tables are given at the end of each section, with the exception of Section 3, where to facilitate understanding of the LSD method, they have been included with the text.« less
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Aerodynamic Limits on Large Civil Tiltrotor Sizing and Efficiency
NASA Technical Reports Server (NTRS)
Acree, C W., Jr.
2014-01-01
The NASA Large Civil Tiltrotor (2nd generation, or LCTR2) has been the reference design for avariety of NASA studies of design optimization, engine and gearbox technology, handling qualities, andother areas, with contributions from NASA Ames, Glenn and Langley Centers, plus academic and industrystudies. Ongoing work includes airfoil design, 3D blade optimization, engine technology studies, andwingrotor aerodynamic interference. The proposed paper will bring the design up to date with the latestresults of such studies, then explore the limits of what aerodynamic improvements might hope toaccomplish. The purpose is two-fold: 1) determine where future technology studies might have the greatestpayoff, and 2) establish a stronger basis of comparison for studies of other vehicle configurations andmissions.
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Interpretive Research Aiming at Theory Building: Adopting and Adapting the Case Study Design
ERIC Educational Resources Information Center
Diaz Andrade, Antonio
2009-01-01
Although the advantages of case study design are widely recognised, its original positivist underlying assumptions may mislead interpretive researchers aiming at theory building. The paper discusses the limitations of the case study design for theory building and explains how grounded theory systemic process adds to the case study design. The…
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Integrating ergonomics in design processes: a case study within an engineering consultancy firm.
Sørensen, Lene Bjerg; Broberg, Ole
2012-01-01
This paper reports on a case study within an engineering consultancy firm, where engineering designers and ergonomists were working together on the design of a new hospital sterile processing plant. The objective of the paper is to gain a better understanding of the premises for integrating ergonomics into engineering design processes and how different factors either promote or limit the integration. Based on a grounded theory approach a model illustrating these factors is developed and different hypotheses about how these factors either promote and/or limit the integration of ergonomics into design processes is presented along with the model.
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ERIC Educational Resources Information Center
Svihla, Vanessa Lynn
2009-01-01
Authentic design commonly involves teams of designers collaborating on ill-structured problems over extended time periods. Nonetheless, design has been studied extensively in sequestered settings, limiting our understanding of design as process and especially of learning design process. This study addresses potential shortcomings of such studies…
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33 CFR 273.14 - Planning procedures.
Code of Federal Regulations, 2011 CFR
2011-07-01
..., D.C. 20314 will be followed by further investigations. Normally, a detailed State design memorandum... information. Field surveys and office studies should be limited to minimum essentials for further detailed... include, but not be limited to, the information contained in Appendix B. (b) State design memorandum. When...
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33 CFR 273.14 - Planning procedures.
Code of Federal Regulations, 2010 CFR
2010-07-01
..., D.C. 20314 will be followed by further investigations. Normally, a detailed State design memorandum... information. Field surveys and office studies should be limited to minimum essentials for further detailed... include, but not be limited to, the information contained in Appendix B. (b) State design memorandum. When...
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33 CFR 273.14 - Planning procedures.
Code of Federal Regulations, 2013 CFR
2013-07-01
..., D.C. 20314 will be followed by further investigations. Normally, a detailed State design memorandum... information. Field surveys and office studies should be limited to minimum essentials for further detailed... include, but not be limited to, the information contained in Appendix B. (b) State design memorandum. When...
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33 CFR 273.14 - Planning procedures.
Code of Federal Regulations, 2012 CFR
2012-07-01
..., D.C. 20314 will be followed by further investigations. Normally, a detailed State design memorandum... information. Field surveys and office studies should be limited to minimum essentials for further detailed... include, but not be limited to, the information contained in Appendix B. (b) State design memorandum. When...
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33 CFR 273.14 - Planning procedures.
Code of Federal Regulations, 2014 CFR
2014-07-01
..., D.C. 20314 will be followed by further investigations. Normally, a detailed State design memorandum... information. Field surveys and office studies should be limited to minimum essentials for further detailed... include, but not be limited to, the information contained in appendix B. (b) State design memorandum. When...
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Limited Scope Design Study for Multi-Sensor Towbody
2016-06-01
FINAL REPORT Limited Scope Design Study for Multi-Sensor Towbody SERDP Project MR-2501 JUNE 2016 Dr. Kevin Williams Tim McGinnis...prepared under contract to the Department of Defense Strategic Environmental Research and Development Program (SERDP). The publication of this...Left Blank REPORT DOCUMENTATION PAGE Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 Form Approved OMB No. 0704-0188 The public
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Systematic Review of the Use of Online Questionnaires among the Geriatric Population
Remillard, Meegan L.; Mazor, Kathleen M.; Cutrona, Sarah L.; Gurwitz, Jerry H.; Tjia, Jennifer
2014-01-01
Background/Objectives The use of internet-based questionnaires to collect information from older adults is not well established. This systematic literature review of studies using online questionnaires in older adult populations aims to 1. describe methodologic approaches to population targeting and sampling and 2. summarize limitations of Internet-based questionnaires in geriatric populations. Design, Setting, Participants We identified English language articles using search terms for geriatric, age 65 and over, Internet survey, online survey, Internet questionnaire, and online questionnaire in PubMed and EBSCO host between 1984 and July 2012. Inclusion criteria were: study population mean age ≥65 years old and use of an online questionnaire for research. Review of 336 abstracts yielded 14 articles for full review by 2 investigators; 11 articles met inclusion criteria. Measurements Articles were extracted for study design and setting, patient characteristics, recruitment strategy, country, and study limitations. Results Eleven (11) articles were published after 2001. Studies had populations with a mean age of 65 to 78 years, included descriptive and analytical designs, and were conducted in the United States, Australia, and Japan. Recruiting methods varied widely from paper fliers and personal emails to use of consumer marketing panels. Investigator-reported study limitations included the use of small convenience samples and limited generalizability. Conclusion Online questionnaires are a feasible method of surveying older adults in some geographic regions and for some subsets of older adults, but limited Internet access constrains recruiting methods and often limits study generalizability. PMID:24635138
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A Parallel Trade Study Architecture for Design Optimization of Complex Systems
NASA Technical Reports Server (NTRS)
Kim, Hongman; Mullins, James; Ragon, Scott; Soremekun, Grant; Sobieszczanski-Sobieski, Jaroslaw
2005-01-01
Design of a successful product requires evaluating many design alternatives in a limited design cycle time. This can be achieved through leveraging design space exploration tools and available computing resources on the network. This paper presents a parallel trade study architecture to integrate trade study clients and computing resources on a network using Web services. The parallel trade study solution is demonstrated to accelerate design of experiments, genetic algorithm optimization, and a cost as an independent variable (CAIV) study for a space system application.
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NASA Technical Reports Server (NTRS)
Kim, S.; Trinh, H. P.
1993-01-01
A gas generator which can be ignited reliably during the initial start-up period and offers fairly uniform gas temperature at the exit was studied numerically. Various sizes and shapes of the mixing enhancement devices and their positions were examined to evaluate the uniformity of the exit gas temperature and the change of internal pressure drop incurred by introducing the mixing enhancement devices. By introducing a turbulence ring and a splash plate with an appropriate size and position, it was possible to obtain fairly uniform gas temperature distributions and a maximum gas temperature that is within the design limit temperature of 1600 R at the generator exit. However, with the geometry studied, the pressure drop across the generator was great, approximately 1150 psi, to satisfy the assigned design limit temperature. If the design limit temperature is increased to 1650 R, the pressure drop across the generator could be lowered by as much as 350 psi.
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Aircraft Survivability: Rotorcraft Survivability. Summer 2010
2010-01-01
Loading of the shafts was conducted using two techniques. The first tech- nique applied a torsion load up to the design limit load after the article...show the ballistic impact and impact damage. Figure 11 shows a 45-degree shaft failure, a common failure type, when loaded to design limit after...SUMMER 2010 ROTORCRAFT Survivability STUDY ON ROTORCRAFT SURVIVABILITY V-22 INTEGRATED SURVIVABILITY DESIGN CH-53K HEAVY LIFT HELICOPTER 9 20 25
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de Hoop, Esther; van der Tweel, Ingeborg; van der Graaf, Rieke; Moons, Karel G M; van Delden, Johannes J M; Reitsma, Johannes B; Koffijberg, Hendrik
2015-10-30
Various papers have addressed pros and cons of the stepped wedge cluster randomized trial design (SWD). However, some issues have not or only limitedly been addressed. Our aim was to provide a comprehensive overview of all merits and limitations of the SWD to assist researchers, reviewers and medical ethics committees when deciding on the appropriateness of the SWD for a particular study. We performed an initial search to identify articles with a methodological focus on the SWD, and categorized and discussed all reported advantages and disadvantages of the SWD. Additional aspects were identified during multidisciplinary meetings in which ethicists, biostatisticians, clinical epidemiologists and health economists participated. All aspects of the SWD were compared to the parallel group cluster randomized design. We categorized the merits and limitations of the SWD to distinct phases in the design and conduct of such studies, highlighting that their impact may vary depending on the context of the study or that benefits may be offset by drawbacks across study phases. Furthermore, a real-life illustration is provided. New aspects are identified within all disciplines. Examples of newly identified aspects of an SWD are: the possibility to measure a treatment effect in each cluster to examine the (in)consistency in effects across clusters, the detrimental effect of lower than expected inclusion rates, deviation from the ordinary informed consent process and the question whether studies using the SWD are likely to have sufficient social value. Discussions are provided on e.g. clinical equipoise, social value, health economical decision making, number of study arms, and interim analyses. Deciding on the use of the SWD involves aspects and considerations from different disciplines not all of which have been discussed before. Pros and cons of this design should be balanced in comparison to other feasible design options as to choose the optimal design for a particular intervention study.
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A Case Study of Educational Computer Game Design by Middle School Students
ERIC Educational Resources Information Center
An, Yun-Jo
2016-01-01
Only a limited number of research studies have investigated how students design educational computer games and its impact on student learning. In addition, most studies on educational game design by students were conducted in the areas of mathematics and science. Using the qualitative case study approach, this study explored how seventh graders…
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Performance evaluation capabilities for the design of physical systems
NASA Technical Reports Server (NTRS)
Pilkey, W. D.; Wang, B. P.
1972-01-01
The results are presented of a study aimed at developing and formulating a capability for the limiting performance of large steady state systems. The accomplishments reported include: (1) development of a theory of limiting performance of large systems subject to steady state inputs; (2) application and modification of PERFORM, the computational capability for the limiting performance of systems with transient inputs; and (3) demonstration that use of an inherently smooth control force for a limiting performance calculation improves the system identification phase of the design process for physical systems subjected to transient loading.
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Psychogeriatric inpatient unit design: a literature review.
Dobrohotoff, John T; Llewellyn-Jones, Robert H
2011-03-01
In many parts of the world the provision of psychogeriatric inpatient units (PGUs) remains limited. More units will be required over coming decades given rapid population aging. Medline (1950-2010), psycINFO (1806-2009), EMBASE (1980-2009) and CINAHL (1982-2009) were searched for papers about PGU design. Selected non-peer reviewed literature such as government reports and unpublished academic dissertations were also reviewed. Data were also obtained from the literature related to general adult psychiatry inpatient units where there was limited information from studies of units designed for older people. Over 200 papers were reviewed and 130 were included. There are few good quality studies to guide the design of acute PGUs and much of the existing literature is based on opinion and anecdote or, at best, based on observational studies. Randomized controlled studies comparing different designs and assessing outcomes are virtually non-existent. Several studies have identified violence and trauma resulting from hospitalization as significant problems with current acute PGU care. Despite its limitations the available literature provides useful guidance on how PGU design can optimize patient and staff safety and improve clinical outcomes. There are significant problems with current acute PGUs, and patient mix on existing units is an important issue. Future research should examine patient and staff perceptions of different PGU ward environments, the relationship between ward design and clinical outcomes, the effects of segregating patients with challenging behaviors in dementia and the benefits or otherwise of gender segregation.
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Automated design of degenerate codon libraries.
Mena, Marco A; Daugherty, Patrick S
2005-12-01
Degenerate codon libraries are frequently used in protein engineering and evolution studies but are often limited to targeting a small number of positions to adequately limit the search space. To mitigate this, codon degeneracy can be limited using heuristics or previous knowledge of the targeted positions. To automate design of libraries given a set of amino acid sequences, an algorithm (LibDesign) was developed that generates a set of possible degenerate codon libraries, their resulting size, and their score relative to a user-defined scoring function. A gene library of a specified size can then be constructed that is representative of the given amino acid distribution or that includes specific sequences or combinations thereof. LibDesign provides a new tool for automated design of high-quality protein libraries that more effectively harness existing sequence-structure information derived from multiple sequence alignment or computational protein design data.
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Reproductive History and Breast Cancer Risk
... of breast cancer. However, these studies had important design limitations that could have affected the results. A ... bias . Prospective studies , which are more rigorous in design and unaffected by such bias, have consistently shown ...
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Common Sense Design for Safe Schools.
ERIC Educational Resources Information Center
Scanlon, Paul W.; Pillar, Rob M.
2000-01-01
Shows how school design can enhance study safety by facilitating supervision. Design concepts of limiting building access to outsiders, creating good traffic flow, and avoiding blind spots and informal gathering areas that resist monitoring are discussed. (GR)
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ERIC Educational Resources Information Center
Churchill, Deirdre Lyne
2014-01-01
This qualitative study examined the impact of architectural design and arrangement on the learning experiences of students. Specifically, it examined how school design and arrangement foster interactions and relationships among students and adults relevant to integral learning experiences. This case study was limited to the breadth of knowledge…
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Anywaine, Zacchaeus; Abaasa, Andrew; Levin, Jonathan; Kasirye, Ronnie; Kamali, Anatoli; Grosskurth, Heiner; Munderi, Paula; Nunn, Andrew
2015-07-01
Cotrimoxazole (CTX) prophylaxis is recommended by the World Health Organisation for HIV infected persons. However, once HIV infected patients have commenced ART in resource limited settings, the benefits of continued CTX prophylaxis are not known. The few studies that investigated the safety of discontinuing CTX prophylaxis in these settings had limitations due to their design. COSTOP is a randomised double blind placebo controlled non-inferiority trial among HIV infected Ugandan adults stabilised on anti-retroviral treatment (ART). Participants with CD4 count of 250 or more cells/mm(3) are randomised to two arms: the intervention arm in which CTX is discontinued and the control arm in which CTX prophylaxis is continued. The study aims to assess whether the intervention regimen is not inferior, with respect to the incidence of pre-defined CTX-preventable events, to the control regimen and superior with respect to the incidence of haematological adverse events. Studies that have previously evaluated the safety of discontinuing CTX prophylaxis among HIV infected adults in resource limited settings have provided moderate to low quality evidence owing in part to methodological limitations. COSTOP is designed and conducted with sufficient rigour to answer this question. The results of the trial will assist in guiding policy recommendations. This paper describes the design and methodological considerations important for the conduct of CTX cessation studies. Copyright © 2015. Published by Elsevier Inc.
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ERIC Educational Resources Information Center
Lowe, Warren C.
This report outlines the limitations and weaknesses of singlecase, time-series research designs, of which the ABAB design is one of the widely used. An alternative design, the simultaneous treatment design, proposed by Browning and Stover (1971), has several advantages over the ABAB design. The design enables an experimenter to simultaneously…
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Horga, Guillermo; Kaur, Tejal; Peterson, Bradley S
2014-06-01
The widespread use of Magnetic Resonance Imaging (MRI) in the study of child- and adult-onset developmental psychopathologies has generated many investigations that have measured brain structure and function in vivo throughout development, often generating great excitement over our ability to visualize the living, developing brain using the attractive, even seductive images that these studies produce. Often lost in this excitement is the recognition that brain imaging generally, and MRI in particular, is simply a technology, one that does not fundamentally differ from any other technology, be it a blood test, a genotyping assay, a biochemical assay, or behavioral test. No technology alone can generate valid scientific findings. Rather, it is only technology coupled with a strong experimental design that can generate valid and reproducible findings that lead to new insights into the mechanisms of disease and therapeutic response. In this review we discuss selected studies to illustrate the most common and important limitations of MRI study designs as most commonly implemented thus far, as well as the misunderstanding that the interpretations of findings from those studies can create for our theories of developmental psychopathologies. Common limitations of MRI study designs are in large part responsible thus far for the generally poor reproducibility of findings across studies, poor generalizability to the larger population, failure to identify developmental trajectories, inability to distinguish causes from effects of illness, and poor ability to infer causal mechanisms in most MRI studies of developmental psychopathologies. For each of these limitations in study design and the difficulties they entail for the interpretation of findings, we discuss various approaches that numerous laboratories are now taking to address those difficulties, which have in common the yoking of brain imaging technologies to studies with inherently stronger designs that permit more valid and more powerful causal inferences. Those study designs include epidemiological, longitudinal, high-risk, clinical trials, and multimodal imaging studies. We highlight several studies that have yoked brain imaging technologies to these stronger designs to illustrate how doing so can aid our understanding of disease mechanisms and in the foreseeable future can improve clinical diagnosis, prevention, and treatment planning for developmental psychopathologies. © 2014 The Authors. Journal of Child Psychology and Psychiatry © 2014 Association for Child and Adolescent Mental Health.
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NASA Astrophysics Data System (ADS)
Moradi, Rasoul; Beheshti, Hamid K.; Lankarani, Hamid M.
2012-12-01
Aircraft occupant crash-safety considerations require a minimum cushion thickness to limit the relative vertical motion of the seat-pelvis during high vertical impact loadings in crash landings or accidents. In military aircraft and helicopter seat design, due to the potential for high vertical accelerations in crash scenarios, the seat system must be provided with an energy absorber to attenuate the acceleration level sustained by the occupants. Because of the limited stroke available for the seat structure, the design of the energy absorber becomes a trade-off problem between minimizing the stroke and maximizing the energy absorption. The available stroke must be used to prevent bottoming out of the seat as well as to absorb maximum impact energy to protect the occupant. In this study, the energy-absorbing system in a rotorcraft seat design is investigated using a mathematical model of the occupant/seat system. Impact theories between interconnected bodies in multibody mechanical systems are utilized to study the impact between the seat pan and the occupant. Experimental responses of the seat system and the occupant are utilized to validate the results from this study for civil and military helicopters according to FAR 23 and 25 and MIL-S-58095 requirements. A model for the load limiter is proposed to minimize the lumbar load for the occupant by minimizing the relative velocity between the seat pan and the occupant's pelvis. The modified energy absorber/load limiter is then implemented for the seat structure so that it absorbs the energy of impact in an effective manner and below the tolerable limit for the occupant in a minimum stroke. Results show that for a designed stroke, the level of occupant lumbar spine injury would be significantly attenuated using this modified energy-absorber system.
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The Design of Time-Series Comparisons under Resource Constraints.
ERIC Educational Resources Information Center
Willemain, Thomas R.; Hartunian, Nelson S.
1982-01-01
Two methods for dividing an interrupted time-series study between baseline and experimental phases when study resources are limited are compared. In fixed designs, the baseline duration is predetermined. In flexible designs the baseline duration is contingent on remaining resources and the match of results to prior expectations of the evaluator.…
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Moving Aerospace Structural Design Practice to a Load and Resistance Factor Approach
NASA Technical Reports Server (NTRS)
Larsen, Curtis E.; Raju, Ivatury S.
2016-01-01
Aerospace structures are traditionally designed using the factor of safety (FOS) approach. The limit load on the structure is determined and the structure is then designed for FOS times the limit load - the ultimate load. Probabilistic approaches utilize distributions for loads and strengths. Failures are predicted to occur in the region of intersection of the two distributions. The load and resistance factor design (LRFD) approach judiciously combines these two approaches by intensive calibration studies on loads and strength to result in structures that are efficient and reliable. This paper discusses these three approaches.
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Design for Manufacture and Assembly for Product Development (Case study : Emergency Lamp)
NASA Astrophysics Data System (ADS)
Ngatilah, Y.; Pulansari, F.; Ernawati, Dira; Pujiastuti, C.; Parwati, C. I.; Prasetyo, B.
2018-01-01
Community needs that are not primary but important in everyday life are lights for lighting. State electricity company (PLN) is experiencing limitations in supplying electricity for this puIDRose. Therefore emergency lights (emergency lights) are already marketed in the community, which limited function only illuminate a very limited space. Therefore we developed the design of energy saving lamps using “Light Emitting Diode” (LED) which can illuminate the whole house as well as functioning as mobile phone charger (HP). The method used is Design for Manufacture and Assembly (DFMA), with the result of design development The percentage increase in assembly efficiency (E) is 0.01071 - 0.00645 = 0.00426 or = 39.76%. The decrease in material costs is IDR 234,000 - IDR 214,000 = IDR 20,000 or = 8.54% .Development design is received because of more assembly efficiency than the initial design. Power usage on previous products with series and designs of the original product can last only 4-5 hours non-stop, while the development of the design can survive 9-10 hours 2x more energy efficient.
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Shim, Jongmyeong; Park, Changsu; Lee, Jinhyung; Kang, Shinill
2016-08-08
Recently, studies have examined techniques for modeling the light distribution of light-emitting diodes (LEDs) for various applications owing to their low power consumption, longevity, and light weight. The energy mapping technique, a design method that matches the energy distributions of an LED light source and target area, has been the focus of active research because of its design efficiency and accuracy. However, these studies have not considered the effects of the emitting area of the LED source. Therefore, there are limitations to the design accuracy for small, high-power applications with a short distance between the light source and optical system. A design method for compensating for the light distribution of an extended source after the initial optics design based on a point source was proposed to overcome such limits, but its time-consuming process and limited design accuracy with multiple iterations raised the need for a new design method that considers an extended source in the initial design stage. This study proposed a method for designing discrete planar optics that controls the light distribution and minimizes the optical loss with an extended source and verified the proposed method experimentally. First, the extended source was modeled theoretically, and a design method for discrete planar optics with the optimum groove angle through energy mapping was proposed. To verify the design method, design for the discrete planar optics was achieved for applications in illumination for LED flash. In addition, discrete planar optics for LED illuminance were designed and fabricated to create a uniform illuminance distribution. Optical characterization of these structures showed that the design was optimal; i.e., we plotted the optical losses as a function of the groove angle, and found a clear minimum. Simulations and measurements showed that an efficient optical design was achieved for an extended source.
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Leong, H M; Carter, Mark; Stephenson, Jennifer
2015-12-01
Sensory integration therapy (SIT) is a controversial intervention that is widely used for people with disabilities. Systematic analysis was conducted on the outcomes of 17 single case design studies on sensory integration therapy for people with, or at-risk of, a developmental or learning disability, disorder or delay. An assessment of the quality of methodology of the studies found most used weak designs and poor methodology, with a tendency for higher quality studies to produce negative results. Based on limited comparative evidence, functional analysis-based interventions for challenging behavior were more effective that SIT. Overall the studies do not provide convincing evidence for the efficacy of sensory integration therapy. Given the findings of the present review and other recent analyses it is advised that the use of SIT be limited to experimental contexts. Issues with the studies and possible improvements for future research are discussed including the need to employ designs that allow for adequate demonstration of experimental control. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Design criteria monograph for valve assemblies
NASA Technical Reports Server (NTRS)
1974-01-01
Monograph is limited to valve selection factors for trade-off studies, configuration analyses, actuator selection, and integration of components. Material is organized along lines of valve design sequence.
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Young Children's Trust in Overtly Misleading Advice
ERIC Educational Resources Information Center
Heyman, Gail D.; Sritanyaratana, Lalida; Vanderbilt, Kimberly E.
2013-01-01
The ability of 3- and 4-year-old children to disregard advice from an overtly misleading informant was investigated across five studies (total "n" =212). Previous studies have documented limitations in young children's ability to reject misleading advice. This study was designed to test the hypothesis that these limitations are primarily…
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ERIC Educational Resources Information Center
Bukova-Guzel, Esra
2007-01-01
The purpose of this study is to design a constructivist learning environment that helps learning the limit concept. The study is a pretest-posttest quasi-experimental research. The control and the experimental groups were chosen from the students attending a calculus course. Worksheets were used to assess students' learning of the limit concept.…
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A new design concept for knitted external vein-graft support mesh.
Singh, Charanpreet; Wang, Xungai
2015-08-01
Autologous vein-graft failure significantly limits the long-term efficacy of coronary artery bypass procedures. The major cause behind this complication is biomechanical mismatch between the vein and coronary artery. The implanted vein experiences a sudden increase (10-12 fold) in luminal pressures. The resulting vein over-distension or 'ballooning' initiates wall thickening phenomenon and ultimate occlusion. Therefore, a primary goal in improving the longevity of a coronary bypass procedure is to inhibit vein over-distension using mechanical constriction. The idea of using an external vein-graft support mesh has demonstrated sustained benefits and wide acceptance in experimental studies. Nitinol based knitted structures have offered more promising mechanical features than other mesh designs owing to their unique loosely looped construction. However, the conventional plain knit construction still exhibits limitations (radial compliance, deployment ease, flexibility, and bending stresses) which limit this design from proving its real clinical advantage. The new knitted mesh design presented in this study is based on the concept of composite knitting utilising high modulus (nitinol and polyester) and low modulus (polyurethane) material components. The experimental comparison of the new design with a plain knit design demonstrated significant improvement in biomechanical (compliance, flexibility, extensibility, viscoelasticity) and procedural (deployment limit) parameters. The results are indicative of the promising role of new mesh in restoring the lost compliance and pulsatility of vein-graft at high arterial pressures. This way it can assist in controlled vein-graft remodelling and stepwise restoration of vein mechanical homoeostasis. Also, improvement in deployment limit parameter offers more flexibility for a surgeon to use a wide range of vein diameters, which may otherwise be rendered unusable for a plain knit mesh. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Design study for a 16x zoom lens system for visible surveillance camera
NASA Astrophysics Data System (ADS)
Vella, Anthony; Li, Heng; Zhao, Yang; Trumper, Isaac; Gandara-Montano, Gustavo A.; Xu, Di; Nikolov, Daniel K.; Chen, Changchen; Brown, Nicolas S.; Guevara-Torres, Andres; Jung, Hae Won; Reimers, Jacob; Bentley, Julie
2015-09-01
*avella@ur.rochester.edu Design study for a 16x zoom lens system for visible surveillance camera Anthony Vella*, Heng Li, Yang Zhao, Isaac Trumper, Gustavo A. Gandara-Montano, Di Xu, Daniel K. Nikolov, Changchen Chen, Nicolas S. Brown, Andres Guevara-Torres, Hae Won Jung, Jacob Reimers, Julie Bentley The Institute of Optics, University of Rochester, Wilmot Building, 275 Hutchison Rd, Rochester, NY, USA 14627-0186 ABSTRACT High zoom ratio zoom lenses have extensive applications in broadcasting, cinema, and surveillance. Here, we present a design study on a 16x zoom lens with 4 groups (including two internal moving groups), designed for, but not limited to, a visible spectrum surveillance camera. Fifteen different solutions were discovered with nearly diffraction limited performance, using PNPX or PNNP design forms with the stop located in either the third or fourth group. Some interesting patterns and trends in the summarized results include the following: (a) in designs with such a large zoom ratio, the potential of locating the aperture stop in the front half of the system is limited, with ray height variations through zoom necessitating a very large lens diameter; (b) in many cases, the lens zoom motion has significant freedom to vary due to near zero total power in the middle two groups; and (c) we discuss the trade-offs between zoom configuration, stop location, packaging factors, and zoom group aberration sensitivity.
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NASA Astrophysics Data System (ADS)
Sakamoto, Yasuaki; Kashiwagi, Takayuki; Hasegawa, Hitoshi; Sasakawa, Takashi; Fujii, Nobuo
This paper describes the design considerations and experimental verification of an LIM rail brake armature. In order to generate power and maximize the braking force density despite the limited area between the armature and the rail and the limited space available for installation, we studied a design method that is suitable for designing an LIM rail brake armature; we considered adoption of a ring winding structure. To examine the validity of the proposed design method, we developed a prototype ring winding armature for the rail brakes and examined its electromagnetic characteristics in a dynamic test system with roller rigs. By repeating various tests, we confirmed that unnecessary magnetic field components, which were expected to be present under high speed running condition or when a ring winding armature was used, were not present. Further, the necessary magnetic field component and braking force attained the desired values. These studies have helped us to develop a basic design method that is suitable for designing the LIM rail brake armatures.
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Low Life Cycle Cost Paratransit Vehicle Design Study
DOT National Transportation Integrated Search
1978-08-01
A preliminary design and cost study was performed for a low life cycle cost paratransit vehicle. The manufacturing technique and cost analysis were based on limited production of 5000 units per year for a ten year period. The vehicle configuration re...
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ERIC Educational Resources Information Center
Xu, Zeyu; Nichols, Austin
2010-01-01
The gold standard in making causal inference on program effects is a randomized trial. Most randomization designs in education randomize classrooms or schools rather than individual students. Such "clustered randomization" designs have one principal drawback: They tend to have limited statistical power or precision. This study aims to…
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ERIC Educational Resources Information Center
Hillsman, Terron L.; Kupritz, Virginia W.
2010-01-01
This ethnographic study extends the findings of earlier research that authenticated the impact of workplace design features on newly acquired communication skills back on the job. The qualitative nature of the earlier study, however, limited quantitative measurement of workplace design features that may have an impact on learned skills. This study…
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Advanced cooling techniques for high-pressure hydrocarbon-fueled engines
NASA Technical Reports Server (NTRS)
Cook, R. T.
1979-01-01
The regenerative cooling limits (maximum chamber pressure) for 02/hydrocarbon gas generator and staged combustion cycle rocket engines over a thrust range of 89,000 N (20,000lbf) to 2,669,000 N (600,000 lbf) for a reusable life of 250 missions were defined. Maximum chamber pressure limits were first determined for the three propellant combinations (O2/CH4, O2/C3H8, and O2/RP-1 without a carbon layer (unenhanced designs). Chamber pressure cooling enhancement limits were then established for seven thermal barriers. The thermal barriers evaluated for these designs were: carbon layer, ceramic coating, graphite liner, film cooling, transpiration cooling, zoned combustion, and a combination of two of the above. All fluid barriers were assessed a 3 percent performance loss. Sensitivity studies were then conducted to determine the influence of cycle life and RP-1 decomposition temperature on chamber pressure limits. Chamber and nozzle design parameters are presented for the unenahanced and enhanced designs. The maximum regenerative cooled chamber pressure limits were attained with the O2/CH4 propellant combination. The O2/RP-1 designs relied on a carbon layer and liquid gas injection chamber contours, short chamber, to be competitive with the other two propellant combinations. This was attributed to the low decomposition temperature of RP-1.
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Selimkhanov, Jangir; Thompson, W. Clayton; Guo, Juen; Hall, Kevin D.; Musante, Cynthia J.
2017-01-01
The design of well-powered in vivo preclinical studies is a key element in building knowledge of disease physiology for the purpose of identifying and effectively testing potential anti-obesity drug targets. However, as a result of the complexity of the obese phenotype, there is limited understanding of the variability within and between study animals of macroscopic endpoints such as food intake and body composition. This, combined with limitations inherent in the measurement of certain endpoints, presents challenges to study design that can have significant consequences for an anti-obesity program. Here, we analyze a large, longitudinal study of mouse food intake and body composition during diet perturbation to quantify the variability and interaction of key metabolic endpoints. To demonstrate how conclusions can change as a function of study size, we show that a simulated pre-clinical study properly powered for one endpoint may lead to false conclusions based on secondary endpoints. We then propose guidelines for endpoint selection and study size estimation under different conditions to facilitate proper power calculation for a more successful in vivo study design. PMID:28392555
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Shardell, Michelle; Harris, Anthony D; El-Kamary, Samer S; Furuno, Jon P; Miller, Ram R; Perencevich, Eli N
2007-10-01
Quasi-experimental study designs are frequently used to assess interventions that aim to limit the emergence of antimicrobial-resistant pathogens. However, previous studies using these designs have often used suboptimal statistical methods, which may result in researchers making spurious conclusions. Methods used to analyze quasi-experimental data include 2-group tests, regression analysis, and time-series analysis, and they all have specific assumptions, data requirements, strengths, and limitations. An example of a hospital-based intervention to reduce methicillin-resistant Staphylococcus aureus infection rates and reduce overall length of stay is used to explore these methods.
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Electrical coupled Morris-Lecar neurons: From design to pattern analysis
DOE Office of Scientific and Technical Information (OSTI.GOV)
Binczak, S.; Behdad, R.; Rossé, M.
2016-06-08
In this study, an experimental electronic neuron based on Morris-Lecar model is presented, able to become an experimental unit tool to study collective association of robust coupled neurons. The circuit design is given according to the ionic currents of this model. A weak coupling of such neurons under Multisim Software can generate clusters based on the boundary conditions of the neurons and their initial conditions. For this study, we work in the region close to the fold bifurcation of limit cycles. In this region two limit cycles exist, one of the cycles is stable and another one is unstable.
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Stiffness Characteristics of Composite Rotor Blades With Elastic Couplings
NASA Technical Reports Server (NTRS)
Piatak, David J.; Nixon, Mark W.; Kosmatka, John B.
1997-01-01
Recent studies on rotor aeroelastic response and stability have shown the beneficial effects of incorporating elastic couplings in composite rotor blades. However, none of these studies have clearly identified elastic coupling limits and the effects of elastic couplings on classical beam stiffnesses of representative rotor blades. Knowledge of these limits and effects would greatly enhance future aeroelastic studies involving composite rotor blades. The present study addresses these voids and provides a preliminary design database for investigators who may wish to study the effects of elastic couplings on representative blade designs. The results of the present study should provide a basis for estimating the potential benefits associated with incorporating elastic couplings without the need for first designing a blade cross section and then performing a cross-section analysis to obtain the required beam section properties as is customary in the usual one-dimensional beam-type approach.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-05-16
... NUCLEAR REGULATORY COMMISSION [NRC-2013-0095] Design Limits and Loading Combinations for Metal... Regulatory Guide (RG) 1.57, ``Design Limits and Loading Combinations for Metal Primary Reactor Containment... the NRC staff considers acceptable for design limits and loading combinations for metal primary...
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Systematic review of the use of online questionnaires of older adults.
Remillard, Meegan L; Mazor, Kathleen M; Cutrona, Sarah L; Gurwitz, Jerry H; Tjia, Jennifer
2014-04-01
To describe methodological approaches to population targeting and sampling and to summarize limitations of Internet-based questionnaires in older adults. Systematic literature review. Studies using online questionnaires in older adult populations. English-language articles using search terms for geriatric, age 65 and over, Internet survey, online survey, Internet questionnaire, and online questionnaire in PubMed and EBSCO host between 1984 and July 2012. Inclusion criteria were study population mean age 65 and older and use of an online questionnaire for research. Review of 336 abstracts yielded 14 articles for full review by two investigators; 11 articles met inclusion criteria. Articles were extracted for study design and setting, participant characteristics, recruitment strategy, country, and study limitations. Eleven articles were published after 2001. Studies had populations with a mean age of 65 to 78, included descriptive and analytical designs, and were conducted in the United States, Australia, and Japan. Recruiting methods varied widely from paper fliers and personal e-mails to use of consumer marketing panels. Investigator-reported study limitations included the use of small convenience samples and limited generalizability. Online questionnaires are a feasible method of surveying older adults in some geographic regions and for some subsets of older adults, but limited Internet access constrains recruiting methods and often limits study generalizability. © 2014, Copyright the Authors Journal compilation © 2014, The American Geriatrics Society.
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Designing and Developing Mobile Based Instruction: A Designer's Perspective
ERIC Educational Resources Information Center
Pastore, Raymond S.; Martin, Florence
2013-01-01
Mobile devices are increasingly being used in classrooms and corporations as a means to deliver instructional content. Currently, there is limited research on how to best design and develop mobile based instruction. As a result, the purpose of this research study was to examine students' perceptions of designing and developing mobile-based…
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NASA Technical Reports Server (NTRS)
Merchant, D. H.
1976-01-01
Methods are presented for calculating design limit loads compatible with probabilistic structural design criteria. The approach is based on the concept that the desired limit load, defined as the largest load occurring in a mission, is a random variable having a specific probability distribution which may be determined from extreme-value theory. The design limit load, defined as a particular of this random limit load, is the value conventionally used in structural design. Methods are presented for determining the limit load probability distributions from both time-domain and frequency-domain dynamic load simulations. Numerical demonstrations of the method are also presented.
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ERIC Educational Resources Information Center
Koo, Tae Seo
2012-01-01
Interdisciplinary design education is becoming more important as design disciplines need various perspectives and solutions. However, only a limited amount of research has been done in regard to interdisciplinary design education. The goal of this study is to begin to answer the question about how designers and researchers develop and improve…
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Myths, Artifacts, and Fatal Flaws: Identifying Limitations and Opportunities in Vitamin C Research
Michels, Alexander J.; Frei, Balz
2013-01-01
Research progress to understand the role of vitamin C (ascorbic acid) in human health has been slow in coming. This is predominantly the result of several flawed approaches to study design, often lacking a full appreciation of the redox chemistry and biology of ascorbic acid. In this review, we summarize our knowledge surrounding the limitations of common approaches used in vitamin C research. In human cell culture, the primary issues are the high oxygen environment, presence of redox-active transition metal ions in culture media, and the use of immortalized cell lines grown in the absence of supplemental ascorbic acid. Studies in animal models are also limited due to the presence of endogenous ascorbic acid synthesis. Despite the use of genetically altered rodent strains lacking synthesis capacity, there are additional concerns that these models do not adequately recapitulate the effects of vitamin C deprivation and supplementation observed in humans. Lastly, several flaws in study design endemic to randomized controlled trials and other human studies greatly limit their conclusions and impact. There also is anecdotal evidence of positive and negative health effects of vitamin C that are widely accepted but have not been substantiated. Only with careful attention to study design and experimental detail can we further our understanding of the possible roles of vitamin C in promoting human health and preventing or treating disease. PMID:24352093
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ERIC Educational Resources Information Center
Bertolli, Jeanne; And Others
1995-01-01
This article discusses methodologic limitations of four observational study designs (ecologic, case-control, cross-sectional, and cohort) that dominate the child abuse and neglect literature and identifies key features of an "ideal" study of child maltreatment. It proposes a new mixed-design strategy, which improves ability to identify child…
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Conceptual design studies of 1985 commercial VTOL transports that utilized rotors, Volume 1
NASA Technical Reports Server (NTRS)
Magee, J. P.; Clark, R. D.; Alexander, H. R.
1974-01-01
Results of conceptual design studies of commercial rotary wing transport aircraft for the 1985 time period are presented. Two aircraft configurations, a tandem helicopter and a tilt rotor, were designed for a 200 nautical mile short haul mission with an upper limit of 100 passengers. In addition to the baseline aircraft two further designs of each configuration are included to assess the impact of external noise design criteria on the aircraft size, weight, and cost.
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Poststroke Seizures and Epilepsy: Clinical Studies and Animal Models
Kelly, Kevin M.
2002-01-01
Poststroke seizures and epilepsy have been described in numerous clinical studies for many years. Most studies are retrospective in design, include relatively small numbers of patients, have limited periods of follow-up, and report a diversity of findings. Well-designed clinical trials and population studies in the recent past addressed several critical clinical issues and generated important findings regarding the occurrence of poststroke seizures and epilepsy. In contrast, the pathophysiologic events of injured brain that establish poststroke epileptogenesis are not well understood, and animal modeling has had limited development. Reviews of several important clinical studies and animal models that hold promise for a better understanding of poststroke epileptogenesis are presented. PMID:15309107
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First wall design of aluminum alloy R-tokamak
NASA Astrophysics Data System (ADS)
Hamada, Y.; Matsuoka, K.; Ogawa, Y.; Kitagawa, S.; Toi, K.; Yamazaki, K.; Abe, Y.; Amano, T.; Fujita, J.; Kaneko, O.; Kawahata, K.; Kuroda, T.; Matsuura, K.; Midzuno, Y.; Naitou, H.; Noda, N.; Ohkubo, K.; Oka, Y.; Sakurai, K.; Tanahashi, S.; Watari, T.
1984-05-01
A design study of a low-activation D-T tokamak Reacting Plasma Project In Nagoya has been finished. The study emphasizes the vacuum vessel and the bumper limiter. Our choice of materials (aluminum vacuum vessel, copper conductors, aluminum TF coil case and lead shield) results in a radiation level of about 1 × 10 -3 times that of a TFTR type design, and 1 × 10 -4 times that of JET type design, at 2 weeks after one D-T shot. Thick graphite tiles will be fixed directly on the aluminum vacuum vessel using aluminum spring washers and bolts. With this simplified structure of the bumper limiter, the inner surface temperature of the thick aluminum vacuum vessel will be less than 120°C which is required to reduce the overaging effect of the aluminum alloy.
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In-Space Manufacturing Baseline Property Development
NASA Technical Reports Server (NTRS)
Stockman, Tom; Schneider, Judith; Prater, Tracie; Bean, Quincy; Werkheiser, Nicki
2016-01-01
The In-Space Manufacturing (ISM) project at NASA Marshall Space Flight Center currently operates a 3D FDM (fused deposition modeling) printer onboard the International Space Station. In order to enable utilization of this capability by designer, the project needs to establish characteristic material properties for materials produced using the process. This is difficult for additive manufacturing since standards and specifications do not yet exist for these technologies. Due to availability of crew time, there are limitations to the sample size which in turn limits the application of the traditional design allowables approaches to develop a materials property database for designers. In this study, various approaches to development of material databases were evaluated for use by designers of space systems who wish to leverage in-space manufacturing capabilities. This study focuses on alternative statistical techniques for baseline property development to support in-space manufacturing.
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Designing Tasks to Promote and Assess Mathematical Transfer in Primary School Children
ERIC Educational Resources Information Center
Clark, Julie; Page, Shaileigh; Thornton, Steve
2013-01-01
This study aims to design learning situations and tasks that promote and assess the capacity of primary school children to transfer mathematical knowledge to new contexts. We discuss previous studies investigating mathematical transfer, and particularly the strengths and limitations of tasks used to assess transfer in these studies. We describe…
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Design Principles of Worked Examples: A Review of the Empirical Studies
ERIC Educational Resources Information Center
Shen, Chun-Yi; Tsai, Hui-Chun
2009-01-01
Many researchers investigated the efficacy of using worked examples in classroom instruction and provided evidence in the effectiveness of worked example instruction in mathematics, computer programming, physics, and etc. However, there are limited studies in worked example design. The purpose of this study is to generate the instructional design…
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Office Design: A Study of Environment.
ERIC Educational Resources Information Center
Manning, Peter, Ed.
Reporting upon a study of environment which was based on the design of office buildings and office space, the study forms part of a continuing program of environmental research sponsored by Pilkington Brothers Limited of St. Helens, England. In this report the word 'environment' is used in the sense of the sum of the physical and emotional…
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Educational Website Design Process: Changes in TPACK Competencies and Experiences
ERIC Educational Resources Information Center
Önal, Nezih; Alemdag, Ecenaz
2018-01-01
The number of technological pedagogical and content knowledge (TPACK) studies has been increasing day by day; however, limited number of studies has provided both quantitative and qualitative findings based on teachers' learning by design experiences. This study aimed to reveal the changes in pre-service teachers' TPACK competencies in the…
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Piepel, Greg F.; Cooley, Scott K.; Vienna, John D.
This article presents a case study of developing an experimental design for a constrained mixture experiment when the experimental region is defined by single-component constraints (SCCs), linear multiple-component constraints (MCCs), and a nonlinear MCC. Traditional methods and software for designing constrained mixture experiments with SCCs and linear MCCs are not directly applicable because of the nonlinear MCC. A modification of existing methodology to account for the nonlinear MCC was developed and is described in this article. The case study involves a 15-component nuclear waste glass example in which SO3 is one of the components. SO3 has a solubility limit inmore » glass that depends on the composition of the balance of the glass. A goal was to design the experiment so that SO3 would not exceed its predicted solubility limit for any of the experimental glasses. The SO3 solubility limit had previously been modeled by a partial quadratic mixture (PQM) model expressed in the relative proportions of the 14 other components. The PQM model was used to construct a nonlinear MCC in terms of all 15 components. In addition, there were SCCs and linear MCCs. This article discusses the waste glass example and how a layered design was generated to (i) account for the SCCs, linear MCCs, and nonlinear MCC and (ii) meet the goals of the study.« less
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14 CFR 29.309 - Design limitations.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Design limitations. 29.309 Section 29.309... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements General § 29.309 Design limitations. The... this subpart: (a) The design maximum and design minimum weights. (b) The main rotor r.p.m. ranges...
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14 CFR 29.309 - Design limitations.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Design limitations. 29.309 Section 29.309... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements General § 29.309 Design limitations. The... this subpart: (a) The design maximum and design minimum weights. (b) The main rotor r.p.m. ranges...
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48 CFR 52.236-22 - Design Within Funding Limitations.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 48 Federal Acquisition Regulations System 2 2012-10-01 2012-10-01 false Design Within Funding....236-22 Design Within Funding Limitations. As prescribed in 36.609-1(c), insert the following clause: Design Within Funding Limitations (APR 1984) (a) The Contractor shall accomplish the design services...
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48 CFR 52.236-22 - Design Within Funding Limitations.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 48 Federal Acquisition Regulations System 2 2011-10-01 2011-10-01 false Design Within Funding....236-22 Design Within Funding Limitations. As prescribed in 36.609-1(c), insert the following clause: Design Within Funding Limitations (APR 1984) (a) The Contractor shall accomplish the design services...
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48 CFR 52.236-22 - Design Within Funding Limitations.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Design Within Funding....236-22 Design Within Funding Limitations. As prescribed in 36.609-1(c), insert the following clause: Design Within Funding Limitations (APR 1984) (a) The Contractor shall accomplish the design services...
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ERIC Educational Resources Information Center
de Castro, Christopher H.
2011-01-01
This study explored the development of student's conceptual understandings of limit and derivative when utilizing specifically designed computational tools. Fourteen students from a secondary Advanced Placement Calculus AB course learned and explored the limit and derivative concepts from differential calculus using visualization tools in the…
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Mandated Change Gone Wrong? A Case Study of Law-Based School Reform in South Africa
ERIC Educational Resources Information Center
Bisschoff, Tom
2009-01-01
Purpose: This paper aims to explore and describe the limits of recent law-based school reform in South Africa from an education management perspective. Design/methodology/approach: The research design consists of a qualitative, investigative, descriptive and contextual design which Merriam would classify as a basic or generic design type.…
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ERIC Educational Resources Information Center
Burke, Catherine; Könings, Karen D.
2016-01-01
Past practices shape and limit the design imagination of teachers, pupils, parents, governors, and others concerned with designing modern schools. Bringing histories of education to the table in the participatory design process of new school buildings and curricula is necessary. Schools having an extraordinary past have the potential to draw from…
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Lean stability augmentation study. [on gas turbine combustion chambers
NASA Technical Reports Server (NTRS)
Mcvey, J. B.; Kennedy, J. B.
1979-01-01
An analytical conceptual design study and an experimental test program were conducted to investigate techniques and develop technology for improving the lean combustion limits of premixing, prevaporizing combustors applicable to gas turbine engine main burners. The use of hot gas pilots, catalyzed flameholder elements, and heat recirculation to augment lean stability limits was considered in the conceptual design study. Tests of flameholders embodying selected concepts were conducted at a pressure of 10 arm and over a range of entrance temperatures simulating conditions to be encountered during stratospheric cruise. The tests were performed using an axisymmetric flametube test rig having a nominal diameter of 10.2 cm. A total of sixteen test configurations were examined in which lean blowout limits, pollutant emission characteristics, and combustor performance were evaluated. The use of a piloted perforated plate flameholder employing a pilot fuel flow rate equivalent to 4 percent of the total fuel flow at a simulated cruise condition resulted in a lean blowout equivalence ratio of less than 0.25 with a design point (T sub zero = 600k, Phi = 0.6) NOx emission index of less than 1.0 g/kg.
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Water-cooled furnace heads for use with standard muffle tube furnaces
NASA Technical Reports Server (NTRS)
Williams, R. J.; Mullins, O.
1975-01-01
The design of water-cooled furnace seals for use in high-temperature controlled-atmosphere gas and vacuum studies is presented in detailed engineering drawings. Limiting design factors and advantages are discussed.
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Three types of solid state remote power controllers
NASA Technical Reports Server (NTRS)
Baker, D. E.
1975-01-01
Three types of solid state Remote Power Controller (RPC) circuits for 120 Vdc spacecraft distribution systems have been developed and evaluated. Both current limiting and noncurrent limiting modes of overload protection were developed and were demonstrated to be feasible. A second generation of circuits was developed which offers comparable performance with substantially less cost and complexity. Electrical efficiency for both generations is 98.5 to 99%. This paper describes various aspects of the circuit design, trade-off studies, and experimental test results. Comparisons of design parameters, component requirements, and engineering model evaluations will emphasize the high efficiency and reliability of the designs.
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A system dynamics approach to develop a recovery model in the Malaysian automotive industry
NASA Astrophysics Data System (ADS)
Mohamad-Ali, N.; Ghazilla, R. A. R.; Abdul-Rashid, S. H.; Sakundarini, N.; Ahmad-Yazid, A.; Stephenie, L.
2017-06-01
Design strategies play a significant role to enhance recovery effectiveness at the end of product life cycle. By reviewing previous study, there are many factors involved to enhance recovery effectiveness but limited to linking design strategies factors in holistic and dynamics view. Proposed method are explained and an initial model for end-of-life vehicles (ELVs) recovery model illustrated in graphical and numerical data is presented. However this is limited to authors understanding and preliminary data which requires collaboration between designers and other stakeholders to develop a model based on actual situation.
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Multidisciplinary design optimization using genetic algorithms
NASA Technical Reports Server (NTRS)
Unal, Resit
1994-01-01
Multidisciplinary design optimization (MDO) is an important step in the conceptual design and evaluation of launch vehicles since it can have a significant impact on performance and life cycle cost. The objective is to search the system design space to determine values of design variables that optimize the performance characteristic subject to system constraints. Gradient-based optimization routines have been used extensively for aerospace design optimization. However, one limitation of gradient based optimizers is their need for gradient information. Therefore, design problems which include discrete variables can not be studied. Such problems are common in launch vehicle design. For example, the number of engines and material choices must be integer values or assume only a few discrete values. In this study, genetic algorithms are investigated as an approach to MDO problems involving discrete variables and discontinuous domains. Optimization by genetic algorithms (GA) uses a search procedure which is fundamentally different from those gradient based methods. Genetic algorithms seek to find good solutions in an efficient and timely manner rather than finding the best solution. GA are designed to mimic evolutionary selection. A population of candidate designs is evaluated at each iteration, and each individual's probability of reproduction (existence in the next generation) depends on its fitness value (related to the value of the objective function). Progress toward the optimum is achieved by the crossover and mutation operations. GA is attractive since it uses only objective function values in the search process, so gradient calculations are avoided. Hence, GA are able to deal with discrete variables. Studies report success in the use of GA for aircraft design optimization studies, trajectory analysis, space structure design and control systems design. In these studies reliable convergence was achieved, but the number of function evaluations was large compared with efficient gradient methods. Applicaiton of GA is underway for a cost optimization study for a launch-vehicle fuel-tank and structural design of a wing. The strengths and limitations of GA for launch vehicle design optimization is studied.
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Katz, Matthew HG; Marsh, Robert; Herman, Joseph M.; Shi, Qian; Collison, Eric; Venook, Alan; Kindler, Hedy; Alberts, Steven; Philip, Philip; Lowy, Andrew M.; Pisters, Peter; Posner, Mitchell; Berlin, Jordan; Ahmad, Syed A.
2017-01-01
Methodological limitations of prior studies have prevented progress in the treatment of patients with borderline resectable pancreatic adenocarcinoma. Shortcomings have included the absence of staging and treatment standards and pre-existing biases with regard to the use of neoadjuvant therapy and the role of vascular resection at pancreatectomy. In this manuscript, we will review limitations of studies of borderline resectable PDAC reported to date, highlight important controversies related to this disease stage, emphasize the research infrastructure necessary for its future study, and present a recently-approved Intergroup pilot study (Alliance A0201101) that will provide a foundation upon which subsequent well-designed clinical trials can be performed. PMID:23435609
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Selimkhanov, J; Thompson, W C; Guo, J; Hall, K D; Musante, C J
2017-08-01
The design of well-powered in vivo preclinical studies is a key element in building the knowledge of disease physiology for the purpose of identifying and effectively testing potential antiobesity drug targets. However, as a result of the complexity of the obese phenotype, there is limited understanding of the variability within and between study animals of macroscopic end points such as food intake and body composition. This, combined with limitations inherent in the measurement of certain end points, presents challenges to study design that can have significant consequences for an antiobesity program. Here, we analyze a large, longitudinal study of mouse food intake and body composition during diet perturbation to quantify the variability and interaction of the key metabolic end points. To demonstrate how conclusions can change as a function of study size, we show that a simulated preclinical study properly powered for one end point may lead to false conclusions based on secondary end points. We then propose the guidelines for end point selection and study size estimation under different conditions to facilitate proper power calculation for a more successful in vivo study design.
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Mueller, Mario J; Stevenson, Graham R
2005-01-01
Increasing projected values of the circulating beam intensity in the Super Proton Synchrotron (SPS) and decreasing limits to radiation exposure, taken with the increasing non-acceptance of unjustified and unoptimised radiation exposures, have led to the need to re-assess the shielding between the ECX and ECA5 underground experimental areas of the SPS. Twenty years ago, these experimental areas at SPS-Point 5 housed the UA1 experiment, where Carlo Rubbia and his team verified the existence of W and Z bosons. The study reported here describes such a re-assessment based on simulations using the multi-purpose FLUKA radiation transport code. This study concludes that while the main shield which is made of concrete blocks and is 4.8 m thick satisfactorily meets the current design limits even at the highest intensities presently planned for the SPS, dose rates calculated for liaison areas on both sides of the main shield significantly exceed the design limits. Possible ways of improving the shielding situation are discussed.
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-08-10
... significant increased prevalence of hypertension. The cross-sectional design of this study (in which subjects.... This study was also cross-sectional in design, limiting its ability to quantify risk, establish a... for significant confounders or by other methodological concerns. Accordingly, [[Page 47927
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Environmental performance evaluation of an advanced-design solid-state television camera
NASA Technical Reports Server (NTRS)
1979-01-01
The development of an advanced-design black-and-white solid-state television camera which can survive exposure to space environmental conditions was undertaken. A 380 x 488 element buried-channel CCD is utilized as the image sensor to ensure compatibility with 525-line transmission and display equipment. Specific camera design approaches selected for study and analysis included: (1) component and circuit sensitivity to temperature; (2) circuit board thermal and mechanical design; and (3) CCD temperature control. Preferred approaches were determined and integrated into the final design for two deliverable solid-state TV cameras. One of these cameras was subjected to environmental tests to determine stress limits for exposure to vibration, shock, acceleration, and temperature-vacuum conditions. These tests indicate performance at the design goal limits can be achieved for most of the specified conditions.
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The Hip Impact Protection Project: Design and Methods
Barton, Bruce A; Birge, Stanley J; Magaziner, Jay; Zimmerman, Sheryl; Ball, Linda; Brown, Kathleen M; Kiel, Douglas P
2013-01-01
Background Nearly 340,000 hip fractures occur each year in the U.S. With current demographic trends, the number of hip fractures is expected to double at least in the next 40 years. Purpose The Hip Impact Protection Project (HIP PRO) was designed to investigate the efficacy and safety of hip protectors in an elderly nursing home population. This paper describes the innovative clustered matched-pair research design used in HIP PRO to overcome the inherent limitations of clustered randomization. Methods Three clinical centers recruited 37 nursing homes to participate in HIP PRO. They were randomized so that the participating residents in that home received hip protectors for either the right or left hip. Informed consent was obtained from either the resident or the resident's responsible party. The target sample size was 580 residents with replacement if they dropped out, had a hip fracture, or died. One of the advantages of the HIP PRO study design was that each resident was his/her own case and control, eliminating imbalances, and there was no confusion over which residents wore pads (or on which hip). Limitations Generalizability of the findings may be limited. Adherence was higher in this study than in other studies because of: (1) the use of a run-in period, (2) staff incentives, and (3) the frequency of adherence assessments. The use of a single pad is not analogous to pad use in the real world and may have caused unanticipated changes in behavior. Fall assessment was not feasible, limiting the ability to analyze fractures as a function of falls. Finally, hip protector designs continue to evolve so that the results generated using this pad may not be applicable to other pad designs. However, information about factors related to adherence will be useful for future studies. Conclusions The clustered matched-pair study design avoided the major problem with previous cluster-randomized investigations of this question – unbalanced risk factors between the experimental group and the control group. Because each resident served as his/her own control, the effects of unbalanced risk factors on treatment effect were virtually eliminated. In addition, the use of frequent adherence assessments allowed us to study the effect of various demographic and environmental factors on adherence, which was vital for the assessment of efficacy. PMID:18697849
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Improving website accessibility for people with early-stage dementia: a preliminary investigation.
Freeman, E D; Clare, Linda; Savitch, Nada; Royan, Lindsay; Litherland, Rachael; Lindsay, Margot
2005-09-01
This study, conducted collaboratively with five men who have a diagnosis of early-stage Alzheimer's disease (AD), is the first stage of a formative research project aimed at developing a new website for people with dementia. Recommendations derived from a literature review of the implications of dementia-related cognitive changes for website design were combined with general web accessibility guidelines to provide a basis for the initial design of a new website. This website was compared with an equivalent site, containing the same information but based on an existing design, in terms of accessibility, ease of use, and user satisfaction. Participants were very satisfied with both sites, but responses did indicate some specific areas where one site was preferred over another. Observational data highlighted significant strengths of the new site as well as some limitations, and resulted in clear recommendations for enhancing the design. In particular, the study suggested that limiting the size of web pages to the amount of information that can be displayed on a computer screen at any one time could reduce the level of difficulty encountered by the participants. The results also suggested the importance of reducing cognitive load through limiting the number of choices required at any one time, the very opposite of the ethos of much website design.
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Open Platform for Limit Protection with Carefree Maneuver Applications
NASA Technical Reports Server (NTRS)
Jeram, Geoffrey J.
2004-01-01
This Open Platform for Limit Protection guides the open design of maneuver limit protection systems in general, and manned, rotorcraft, aerospace applications in particular. The platform uses three stages of limit protection modules: limit cue creation, limit cue arbitration, and control system interface. A common set of limit cue modules provides commands that can include constraints, alerts, transfer functions, and friction. An arbitration module selects the "best" limit protection cues and distributes them to the most appropriate control path interface. This platform adopts a holistic approach to limit protection whereby it considers all potential interface points, including the pilot's visual, aural, and tactile displays; and automatic command restraint shaping for autonomous limit protection. For each functional module, this thesis guides the control system designer through the design choices and information interfaces among the modules. Limit cue module design choices include type of prediction, prediction mechanism, method of critical control calculation, and type of limit cue. Special consideration is given to the nature of the limit, particularly the level of knowledge about it, and the ramifications for limit protection design, especially with respect to intelligent control methods such as fuzzy inference systems and neural networks.
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ERIC Educational Resources Information Center
Texas Education Agency, Austin.
The Texas Successful Schools Study profiled the contributions of programs, policies, and school personnel to the academic success of limited English proficient (LEP) students in seven successful elementary schools. This guide shares study information with school administrators to assist them in designing, implementing, and enhancing programs for…
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Study of capabilities and limitations of 3D printing technology
NASA Astrophysics Data System (ADS)
Lemu, H. G.
2012-04-01
3D printing is one of the developments in rapid prototyping technology. The inception and development of the technology has highly assisted the product development phase of product design and manufacturing. The technology is particularly important in educating product design and 3D modeling because it helps students to visualize their design idea, to enhance their creative design process and enables them to touch and feel the result of their innovative work. The availability of many 3D printers on the market has created a certain level of challenge for the user. Among others, complexity of part geometry, material type, compatibility with 3D CAD models and other technical aspects still need in-depth study. This paper presents results of the experimental work on the capabilities and limitations of the Z510 3D printer from Z-corporation. Several parameters such as dimensional and geometrical accuracy, surface quality and strength as a function of model size, orientation and file exchange format are closely studied.
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48 CFR 36.609-1 - Design within funding limitations.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Design within funding... Services 36.609-1 Design within funding limitations. (a) The Government may require the architect-engineer... limit (funding limitation). If the price of construction proposed in response to a Government...
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Improved specificity of TALE-based genome editing using an expanded RVD repertoire.
Miller, Jeffrey C; Zhang, Lei; Xia, Danny F; Campo, John J; Ankoudinova, Irina V; Guschin, Dmitry Y; Babiarz, Joshua E; Meng, Xiangdong; Hinkley, Sarah J; Lam, Stephen C; Paschon, David E; Vincent, Anna I; Dulay, Gladys P; Barlow, Kyle A; Shivak, David A; Leung, Elo; Kim, Jinwon D; Amora, Rainier; Urnov, Fyodor D; Gregory, Philip D; Rebar, Edward J
2015-05-01
Transcription activator-like effector (TALE) proteins have gained broad appeal as a platform for targeted DNA recognition, largely owing to their simple rules for design. These rules relate the base specified by a single TALE repeat to the identity of two key residues (the repeat variable diresidue, or RVD) and enable design for new sequence targets via modular shuffling of these units. A key limitation of these rules is that their simplicity precludes options for improving designs that are insufficiently active or specific. Here we address this limitation by developing an expanded set of RVDs and applying them to improve the performance of previously described TALEs. As an extreme example, total conversion of a TALE nuclease to new RVDs substantially reduced off-target cleavage in cellular studies. By providing new RVDs and design strategies, these studies establish options for developing improved TALEs for broader application across medicine and biotechnology.
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Torrens, George Edward
2018-01-01
Summative content analysis was used to define methods and heuristics from each case study. The review process was in two parts: (1) A literature review to identify conventional research methods and (2) a summative content analysis of published case studies, based on the identified methods and heuristics to suggest an order and priority of where and when were used. Over 200 research and design methods and design heuristics were identified. From the review of the 20 case studies 42 were identified as being applied. The majority of methods and heuristics were applied in phase two, market choice. There appeared a disparity between the limited numbers of methods frequently used, under 10 within the 20 case studies, when hundreds were available. Implications for Rehabilitation The communication highlights a number of issues that have implication for those involved in assistive technology new product development: •The study defined over 200 well-established research and design methods and design heuristics that are available for use by those who specify and design assistive technology products, which provide a comprehensive reference list for practitioners in the field; •The review within the study suggests only a limited number of research and design methods are regularly used by industrial design focused assistive technology new product developers; and, •Debate is required within the practitioners working in this field to reflect on how a wider range of potentially more effective methods and heuristics may be incorporated into daily working practice.
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Aerodynamic Limits on Large Civil Tiltrotor Sizing and Efficiency
NASA Technical Reports Server (NTRS)
Acree, C W.
2014-01-01
The NASA Large Civil Tiltrotor (2nd generation, or LCTR2) is a useful reference design for technology impact studies. The present paper takes a broad view of technology assessment by examining the extremes of what aerodynamic improvements might hope to accomplish. Performance was analyzed with aerodynamically idealized rotor, wing, and airframe, representing the physical limits of a large tiltrotor. The analysis was repeated with more realistic assumptions, which revealed that increased maximum rotor lift capability is potentially more effective in improving overall vehicle efficiency than higher rotor or wing efficiency. To balance these purely theoretical studies, some practical limitations on airframe layout are also discussed, along with their implications for wing design. Performance of a less efficient but more practical aircraft with non-tilting nacelles is presented.
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A global parallel model based design of experiments method to minimize model output uncertainty.
Bazil, Jason N; Buzzard, Gregory T; Rundell, Ann E
2012-03-01
Model-based experiment design specifies the data to be collected that will most effectively characterize the biological system under study. Existing model-based design of experiment algorithms have primarily relied on Fisher Information Matrix-based methods to choose the best experiment in a sequential manner. However, these are largely local methods that require an initial estimate of the parameter values, which are often highly uncertain, particularly when data is limited. In this paper, we provide an approach to specify an informative sequence of multiple design points (parallel design) that will constrain the dynamical uncertainty of the biological system responses to within experimentally detectable limits as specified by the estimated experimental noise. The method is based upon computationally efficient sparse grids and requires only a bounded uncertain parameter space; it does not rely upon initial parameter estimates. The design sequence emerges through the use of scenario trees with experimental design points chosen to minimize the uncertainty in the predicted dynamics of the measurable responses of the system. The algorithm was illustrated herein using a T cell activation model for three problems that ranged in dimension from 2D to 19D. The results demonstrate that it is possible to extract useful information from a mathematical model where traditional model-based design of experiments approaches most certainly fail. The experiments designed via this method fully constrain the model output dynamics to within experimentally resolvable limits. The method is effective for highly uncertain biological systems characterized by deterministic mathematical models with limited data sets. Also, it is highly modular and can be modified to include a variety of methodologies such as input design and model discrimination.
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Rosenbloom, Daniel I S; Elliott, Oliver; Hill, Alison L; Henrich, Timothy J; Siliciano, Janet M; Siliciano, Robert F
2015-12-01
Limiting dilution assays are widely used in infectious disease research. These assays are crucial for current human immunodeficiency virus (HIV)-1 cure research in particular. In this study, we offer new tools to help investigators design and analyze dilution assays based on their specific research needs. Limiting dilution assays are commonly used to measure the extent of infection, and in the context of HIV they represent an essential tool for studying latency and potential curative strategies. Yet standard assay designs may not discern whether an intervention reduces an already miniscule latent infection. This review addresses challenges arising in this setting and in the general use of dilution assays. We illustrate the major statistical method for estimating frequency of infectious units from assay results, and we offer an online tool for computing this estimate. We recommend a procedure for customizing assay design to achieve desired sensitivity and precision goals, subject to experimental constraints. We consider experiments in which no viral outgrowth is observed and explain how using alternatives to viral outgrowth may make measurement of HIV latency more efficient. Finally, we discuss how biological complications, such as probabilistic growth of small infections, alter interpretations of experimental results.
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The use of medication in selective mutism: a systematic review.
Manassis, Katharina; Oerbeck, Beate; Overgaard, Kristin Romvig
2016-06-01
Despite limited evidence, selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs) are used to reduce symptoms of selective mutism (SM) in children unresponsive to psychosocial interventions. We review existing evidence for the efficacy of these medications, limitations of the literature, and resulting treatment considerations. Bibliographic searches were conducted in Medline, Embase, PsycInfo, Web of Science and Cochrane up to June 2015. Two reviewers independently sought studies of children with SM as primary psychiatric diagnosis, which reported response to medication treatment. Abstracts were limited to those reporting original data. Two reviewers independently assessed the ten papers reporting on >2 subjects regarding study design, key results, and limitations. Heterogeneity of designs mandated a descriptive summary. Symptomatic improvement was found for 66/79 children treated with SSRIs and 4/4 children treated with phenelzine. Only 3/10 studies had unmedicated comparison groups and only two were double-blinded. This review may be affected by publication bias, missed studies, and variability of outcome measures in included studies. Although there is some evidence for symptomatic improvement in SM with medication, especially SSRIs, it is limited by small numbers, lack of comparative trials, lack of consistent measures, and lack of consistent reporting on tolerability. The clinician must weigh this paucity of evidence against the highly debilitating nature of SM, and its adverse effects on the development of those children whose progress with psychosocial interventions is limited or very slow. Studies of optimal dosage and timing of medications in relation to psychosocial treatments are also needed.
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NASA Technical Reports Server (NTRS)
Cavicchi, Richard H
1956-01-01
Turbine centrifugal stress is a limiting factor for all flight conditions studied. This stress is more severe for sea-level operations than for subsonic flight at the tropopause. Turbines designed for a stress of 30,000 psi are capable of driving a light, compact, high-spedd compressor but only at high values of specific fuel consumption. An increase in turbine-inlet temperature is accompanied by an increase in turbine centrifugal stress. If stresses in excess of 50,000 psi can be tolerated, compressor aerodynamics may become a primary limitation.
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14 CFR 27.309 - Design limitations.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Design limitations. 27.309 Section 27.309... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements General § 27.309 Design limitations. The... this subpart: (a) The design maximum weight. (b) The main rotor r.p.m. ranges power on and power off...
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14 CFR 27.309 - Design limitations.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Design limitations. 27.309 Section 27.309... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements General § 27.309 Design limitations. The... this subpart: (a) The design maximum weight. (b) The main rotor r.p.m. ranges power on and power off...
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Do Particular Design Features Assist People with Aphasia to Comprehend Text? An Exploratory Study
ERIC Educational Resources Information Center
Wilson, Lucy; Read, Jennifer
2016-01-01
Background: Much of the evidence underlying guidelines for producing accessible information for people with aphasia focuses on client preference for particular design features. There is limited evidence regarding the effects of these features on comprehension. Aims: To examine the effects of specific design features on text comprehension. It was…
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Adults Living with Limited Literacy and Chronic Illness: Patient Education Experiences
ERIC Educational Resources Information Center
King, Judy; Taylor, Maurice C.
2010-01-01
The purpose of this study was to investigate how Canadian adults living with limited literacy and chronic illness made meaning of their patient education experiences. The study used a hermeneutic phenomenological research design and employed three data sources over a nine-month period. Data was interpreted and analyzed as it was collected,…
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Reasons Given by Older People for Limitation or Avoidance of Driving
ERIC Educational Resources Information Center
Ragland, David R.; Satariano, William A.; MacLeod, Kara E.
2004-01-01
Purpose: To understand the driving behavior of older adults, this study examines self-reported reasons for driving limitation or avoidance. Design and Methods: Baseline interviews were conducted (n = 2,046) as part of a community-based study of aging and physical performance in persons aged 55 years or older in Sonoma, California. Twenty-one…
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Definition of smolder experiments for Spacelab
NASA Technical Reports Server (NTRS)
Summerfield, M.; Messina, N. A.; Ingram, L. S.
1979-01-01
The feasibility of conducting experiments in space on smoldering combustion was studied to conceptually design specific smoldering experiments to be conducted in the Shuttle/Spacelab System. Design information for identified experiment critical components is provided. The analytical and experimental basis for conducting research on smoldering phenomena in space was established. Physical descriptions of the various competing processes pertaining to smoldering combustion were identified. The need for space research was defined based on limitations of existing knowledge and limitations of ground-based reduced-gravity experimental facilities.
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Design and analysis of post-marketing research.
Zhou, Xiao-Hua Andrew; Yang, Wei
2013-07-01
A post-marketing study is an integral part of research that helps to ensure a favorable risk-benefit profile for approved drugs used in the market. Because most of post-marketing studies use observational designs, which are liable to confounding, estimation of the causal effect of a drug versus a comparative one is very challenging. This article focuses on methodological issues of importance in designing and analyzing studies to evaluate the safety of marketed drugs, especially marketed traditional Chinese medicine (TCM) products. Advantages and limitations of the current designs and analytic methods for postmarketing studies are discussed, and recommendations are given for improving the validity of postmarketing studies in TCM products.
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Low Pressure Greenhouse Concepts for Mars
NASA Technical Reports Server (NTRS)
Fowler, Philip A.; Wheeler, Raymond M.; Bucklin, Ray A.; Corey, Kenneth A.
2000-01-01
A project was initiated to begin testing some environmental limits for managing plant growth systems. These limits will help determine some of the concepts for building plant enclosures for use on Mars. In particular, this study focuses on the effects of reduced atmospheric pressures. Structural design is considered as it relates to the biological processes that would occur within that structure. The design must be closely tied to the functionality of the biological system and has a few primary concerns that need to be tested to resolve the question as to the path of the design. Early tests indicate that plants can survive and grow at low (greater than 76 mb) pressure.
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Development and evaluation of task-specific NLP framework in China.
Ge, Caixia; Zhang, Yinsheng; Huang, Zhenzhen; Jia, Zheng; Ju, Meizhi; Duan, Huilong; Li, Haomin
2015-01-01
Natural language processing (NLP) has been designed to convert narrative text into structured data. Although some general NLP architectures have been developed, a task-specific NLP framework to facilitate the effective use of data is still a challenge in lexical resource limited regions, such as China. The purpose of this study is to design and develop a task-specific NLP framework to extract targeted information from particular documents by adopting dedicated algorithms on current limited lexical resources. In this framework, a shared and evolving ontology mechanism was designed. The result has shown that such a free text driven platform will accelerate the NLP technology acceptance in China.
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ERIC Educational Resources Information Center
Mintz, Chelsey A.
2017-01-01
The purpose of this action research study was to examine the effects of implementing an online professional learning community (PLC) designed explicitly for teachers of gifted and talented (GT) English language arts (ELA) courses. The present action research (AR) is a limited mixed design study, including quantitative and qualitative elements, to…
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Comparison of Geometric Design of a Brand of Stainless Steel K-Files: An In Vitro Study.
Saeedullah, Maryam; Husain, Syed Wilayat
2018-04-01
The purpose of this experimental study was to determine the diametric variations of a brand of handheld stainless-steel K-files, acquired from different countries, in accordance with the available standards. 20 Mani stainless-steel K-files of identical size (ISO#25) were acquired from Pakistan and were designated as Group A while 20 Mani K-files were purchased from London, UK and designated as Group B. Files were assessed using profile projector Nikon B 24V. Data was statistically compared with ISO 3630:1 and ADA 101 by one sample T test. Significant difference was found between Groups A and B. Average discrepancy of Group A fell within the tolerance limit while that of Group B exceeded the limit. Findings in this study call attention towards adherence to the dimensional standards of stainless-steel endodontic files.
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49 CFR 192.123 - Design limitations for plastic pipe.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 3 2012-10-01 2012-10-01 false Design limitations for plastic pipe. 192.123... Design limitations for plastic pipe. (a) Except as provided in paragraph (e) and paragraph (f) of this section, the design pressure may not exceed a gauge pressure of 100 psig (689 kPa) for plastic pipe used...
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49 CFR 192.123 - Design limitations for plastic pipe.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 3 2014-10-01 2014-10-01 false Design limitations for plastic pipe. 192.123... Design limitations for plastic pipe. (a) Except as provided in paragraph (e) and paragraph (f) of this section, the design pressure may not exceed a gauge pressure of 100 psig (689 kPa) for plastic pipe used...
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49 CFR 192.123 - Design limitations for plastic pipe.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 3 2013-10-01 2013-10-01 false Design limitations for plastic pipe. 192.123... Design limitations for plastic pipe. (a) Except as provided in paragraph (e) and paragraph (f) of this section, the design pressure may not exceed a gauge pressure of 100 psig (689 kPa) for plastic pipe used...
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Balloon-borne three-meter telescope for far-infrared and submillimeter astronomy
NASA Technical Reports Server (NTRS)
Fazio, Giovanni G.
1986-01-01
The study and revision of the gimbal design of the Three-Meter Balloon Borne Telescope (TMBBT) is discussed. Efforts were made to eliminate the alignment and limited rotation problems inherent in the flex-pivot design. A new design using ball bearings to replace the flex-pivots was designed and its performance analyzed. An error analysis for the entire gondola pointing system was also prepared.
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Code of Federal Regulations, 2013 CFR
2013-04-01
... applicant's existing facilities; (5) A flow diagram or comparative study showing daily design capacity... designed to meet the goal of limiting the perceived noise at NSAs to an Ldn of 55 dBA or what mitigation...
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Code of Federal Regulations, 2012 CFR
2012-04-01
... applicant's existing facilities; (5) A flow diagram or comparative study showing daily design capacity... designed to meet the goal of limiting the perceived noise at NSAs to an Ldn of 55 dBA or what mitigation...
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Code of Federal Regulations, 2011 CFR
2011-04-01
... applicant's existing facilities; (5) A flow diagram or comparative study showing daily design capacity... designed to meet the goal of limiting the perceived noise at NSAs to an Ldn of 55 dBA or what mitigation...
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Code of Federal Regulations, 2010 CFR
2010-04-01
... applicant's existing facilities; (5) A flow diagram or comparative study showing daily design capacity... designed to meet the goal of limiting the perceived noise at NSAs to an Ldn of 55 dBA or what mitigation...
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Code of Federal Regulations, 2014 CFR
2014-04-01
... applicant's existing facilities; (5) A flow diagram or comparative study showing daily design capacity... designed to meet the goal of limiting the perceived noise at NSAs to an Ldn of 55 dBA or what mitigation...
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Designing with non-linear viscoelastic fluids
NASA Astrophysics Data System (ADS)
Schuh, Jonathon; Lee, Yong Hoon; Allison, James; Ewoldt, Randy
2017-11-01
Material design is typically limited to hard materials or simple fluids; however, design with more complex materials can provide ways to enhance performance. Using the Criminale-Ericksen-Filbey (CEF) constitutive model in the thin film lubrication limit, we derive a modified Reynolds Equation (based on asymptotic analysis) that includes shear thinning, first normal stress, and terminal regime viscoelastic effects. This allows for designing non-linear viscoelastic fluids in thin-film creeping flow scenarios, i.e. optimizing the shape of rheological material properties to achieve different design objectives. We solve the modified Reynolds equation using the pseudo-spectral method, and describe a case study in full-film lubricated sliding where optimal fluid properties are identified. These material-agnostic property targets can then guide formulation of complex fluids which may use polymeric, colloidal, or other creative approaches to achieve the desired non-Newtonian properties.
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Studies using single-subject designs in sport psychology: 30 years of research
Martin, Garry L.; Thompson, Kendra; Regehr, Kaleigh
2004-01-01
A prominent feature of behavior-analytic research has been the use of single-subject designs. We examined sport psychology journals and behavioral journals published during the past 30 years, and located 40 studies using single-subject designs to assess interventions for enhancing the performance of athletes and coaches. In this paper, we summarize that body of research, discuss its strengths and limitations, and identify areas for future research. PMID:22478434
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Wilson, S; McKenzie, K; Quayle, E; Murray, G
2014-01-01
The family support needs of parents with an intellectual disability (ID) are relatively unknown. This paper reviewed two types of intervention for parents with ID: those designed to strengthen social relationships and those teaching parenting skills. A literature search was conducted using electronic databases and a limited number of evaluative studies were found. The evidence for interventions aimed at strengthening social relationships was inconclusive; although positive changes were observed, there were limitations in study design which restricted the generalizability of the results. The evidence for parental skills teaching suggested that behavioural based interventions are more effective than less intensive forms such as lesson booklets and the provision of normal services, although these studies also had limitations. There is a need for further large scale controlled studies in this area to provide clearer evidence and to explore additional factors relating to child, parent and family which may impact on outcomes. © 2013 John Wiley & Sons Ltd.
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Large strain cruciform biaxial testing for FLC detection
NASA Astrophysics Data System (ADS)
Güler, Baran; Efe, Mert
2017-10-01
Selection of proper test method, specimen design and analysis method are key issues for studying formability of sheet metals and detection of their forming limit curves (FLC). Materials with complex microstructures may need an additional micro-mechanical investigation and accurate modelling. Cruciform biaxial test stands as an alternative to standard tests as it achieves frictionless, in-plane, multi-axial stress states with a single sample geometry. In this study, we introduce a small-scale (less than 10 cm) cruciform sample allowing micro-mechanical investigation at stress states ranging from plane strain to equibiaxial. With successful specimen design and surface finish, large forming limit strains are obtained at the test region of the sample. The large forming limit strains obtained by experiments are compared to the values obtained from Marciniak-Kuczynski (M-K) local necking model and Cockroft-Latham damage model. This comparison shows that the experimental limiting strains are beyond the theoretical values, approaching to the fracture strain of the two test materials: Al-6061-T6 aluminum alloy and DC-04 high formability steel.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Duffey, R.B.; Rohatgi, U.S.
Maximum power limits for hypothetical designs of natural circulation plants can be described analytically. The thermal hydraulic design parameters are those which limit the flow, being the elevations, flow areas, and loss coefficients. WE have found some simple ``design`` equations for natural circulation flow to power ratio, and for the stability limit. The analysis of historical and available data for maximum capacity factor estimation shows 80% to be reasonable and achievable. The least cost is obtained by optimizing both hypothetical plant performance for a given output,a nd the plant layout and design. There is also scope to increase output andmore » reduce cost by considering design variations of primary and secondary pressure, and by optimizing component elevations and loss coefficients. The design limits for each are set by stability and maximum flow considerations, which deserve close and careful evaluation.« less
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Study of wrap-rib antenna design
NASA Technical Reports Server (NTRS)
Wade, W. D.; Sinha, A.; Singh, R.
1979-01-01
The results of a parametric design study conducted to develop the significant characteristics and technology limitations of space deployable antenna systems with aperture sizes ranging from 50 up to 300 m and F/D ratios between 0.5 and 3.0 are presented. Wrap/rib type reflectors of both the prime and offset fed geometry and associated feed support structures were considered. The significant constraints investigated as limitations on achievable aperture were inherent manufacturability, orbit dynamic and thermal stability, antenna weight, and antenna stowed volume. A data base, resulting in the defined maximum achievable aperture size as a function of diameter, frequency and estimated cost, was formed.
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NASA Technical Reports Server (NTRS)
Jefferies, K. S.; Tew, R. C.
1974-01-01
A digital computer study was made of reactor thermal transients during startup of the Brayton power conversion loop of a 60-kWe reactor Brayton power system. A startup procedure requiring the least Brayton system complication was tried first; this procedure caused violations of design limits on key reactor variables. Several modifications of this procedure were then found which caused no design limit violations. These modifications involved: (1) using a slower rate of increase in gas flow; (2) increasing the initial reactor power level to make the reactor respond faster; and (3) appropriate reactor control drum manipulation during the startup transient.
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ERIC Educational Resources Information Center
Wing, Coady; Cook, Thomas D.
2013-01-01
The sharp regression discontinuity design (RDD) has three key weaknesses compared to the randomized clinical trial (RCT). It has lower statistical power, it is more dependent on statistical modeling assumptions, and its treatment effect estimates are limited to the narrow subpopulation of cases immediately around the cutoff, which is rarely of…
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Evidence from Biochemical Pathways in Favor of Unfinished Evolution Rather than Intelligent Design
ERIC Educational Resources Information Center
Behrman, Edward J.; Marzluf, George A.
2004-01-01
An argument is made in favor of imperfect or unfinished evolution based on some metabolic pathways in which it seems that intelligent design would have done better. The case studies noted indicate the absence of highly intelligent design and are not intended as comprehensive collection but as a limited sample of inefficient situations in…
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Methods for Combining Payload Parameter Variations with Input Environment
NASA Technical Reports Server (NTRS)
Merchant, D. H.; Straayer, J. W.
1975-01-01
Methods are presented for calculating design limit loads compatible with probabilistic structural design criteria. The approach is based on the concept that the desired limit load, defined as the largest load occuring in a mission, is a random variable having a specific probability distribution which may be determined from extreme-value theory. The design limit load, defined as a particular value of this random limit load, is the value conventionally used in structural design. Methods are presented for determining the limit load probability distributions from both time-domain and frequency-domain dynamic load simulations. Numerical demonstrations of the methods are also presented.
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ERIC Educational Resources Information Center
Newcomer, Laurie J.
2010-01-01
It is essential to provide high quality interventions designed to improve struggling readers' reading comprehension while making use of limited resources. This study explored, through an holistic, multiple-case study design, volunteer-student interactions and activities in an after school reading program utilizing minimally-trained volunteers. The…
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How Revisions to Mathematical Visuals Affect Cognition: Evidence from Eye Tracking
ERIC Educational Resources Information Center
Clinton, Virginia; Cooper, Jennifer L.; Michaelis, Joseph; Alibali, Martha W.; Nathan, Mitchell J.
2017-01-01
Mathematics curricula are frequently rich with visuals, but these visuals are often not designed for optimal use of students' limited cognitive resources. The authors of this study revised the visuals in a mathematics lesson based on instructional design principles. The purpose of this study is to examine the effects of these revised visuals on…
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Immuno-oncology Clinical Trial Design: Limitations, Challenges, and Opportunities
Baik, Christina S.; Rubin, Eric H.; Forde, Patrick M.; Mehnert, Janice M.; Collyar, Deborah; Butler, Marcus O.; Dixon, Erica L.; Chow, Laura Q.M.
2017-01-01
Recent advances in immuno-oncology and regulatory approvals have been rapid and paradigm shifting in many difficult-to-treat malignancies. Despite immune checkpoint inhibitor therapy becoming the standard of care across multiple tumor types, there are many unanswered questions that need to be addressed before this therapeutic modality can be fully harnessed. Areas of limitations include treatment of patients not sufficiently represented in clinical trials, uncertainty of the optimal treatment dosing and duration, and lack of understanding regarding long-term immune related toxicities and atypical tumor responses. Patients such as those with autoimmune disease, chronic viral infections, limited performance status, and brain metastases were often excluded from initial trials due to concerns of safety. However, limited data suggest that some of these patients can benefit from therapy with manageable toxicities; thus, future studies should incorporate these patients to clearly define safety and efficacy. There are still controversies regarding the optimal dosing strategy that can vary from weight-based to flat dosing, with undefined treatment duration. Further elucidation of the optimal dosing approach and evaluation of predictive biomarkers should be incorporated in the design of future trials. Finally, there are long-term immune-mediated toxicities, atypical tumor responses such as pseudoprogression and endpoints unique to immuno-oncology that are not adequately captured by traditional trial designs; thus, novel study designs are needed. In this article, we discuss in detail the above challenges and propose needed areas of research for exploration and incorporation in the next generation of immuno-oncology clinical trials. PMID:28864727
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CFD-Based Design Optimization Tool Developed for Subsonic Inlet
NASA Technical Reports Server (NTRS)
1995-01-01
The traditional approach to the design of engine inlets for commercial transport aircraft is a tedious process that ends with a less-than-optimum design. With the advent of high-speed computers and the availability of more accurate and reliable computational fluid dynamics (CFD) solvers, numerical optimization processes can effectively be used to design an aerodynamic inlet lip that enhances engine performance. The designers' experience at Boeing Corporation showed that for a peak Mach number on the inlet surface beyond some upper limit, the performance of the engine degrades excessively. Thus, our objective was to optimize efficiency (minimize the peak Mach number) at maximum cruise without compromising performance at other operating conditions. Using a CFD code NPARC, the NASA Lewis Research Center, in collaboration with Boeing, developed an integrated procedure at Lewis to find the optimum shape of a subsonic inlet lip and a numerical optimization code, ADS. We used a GRAPE-based three-dimensional grid generator to help automate the optimization procedure. The inlet lip shape at the crown and the keel was described as a superellipse, and the superellipse exponents and radii ratios were considered as design variables. Three operating conditions: cruise, takeoff, and rolling takeoff, were considered in this study. Three-dimensional Euler computations were carried out to obtain the flow field. At the initial design, the peak Mach numbers for maximum cruise, takeoff, and rolling takeoff conditions were 0.88, 1.772, and 1.61, respectively. The acceptable upper limits on the takeoff and rolling takeoff Mach numbers were 1.55 and 1.45. Since the initial design provided by Boeing was found to be optimum with respect to the maximum cruise condition, the sum of the peak Mach numbers at takeoff and rolling takeoff were minimized in the current study while the maximum cruise Mach number was constrained to be close to that at the existing design. With this objective, the optimum design satisfied the upper limits at takeoff and rolling takeoff while retaining the desirable cruise performance. Further studies are being conducted to include static and cross-wind operating conditions in the design optimization procedure. This work was carried out in collaboration with Dr. E.S. Reddy of NYMA, Inc.
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Design and Analysis of Tooth Impact Test Rig for Spur Gear
NASA Astrophysics Data System (ADS)
Ghazali, Wafiuddin Bin Md; Aziz, Ismail Ali Bin Abdul; Daing Idris, Daing Mohamad Nafiz Bin; Ismail, Nurazima Binti; Sofian, Azizul Helmi Bin
2016-02-01
This paper is about the design and analysis of a prototype of tooth impact test rig for spur gear. The test rig was fabricated and analysis was conducted to study its’ limitation and capabilities. The design of the rig is analysed to ensure that there will be no problem occurring during the test and reliable data can be obtained. From the result of the analysis, the maximum amount of load that can be applied, the factor of safety of the machine, the stresses on the test rig parts were determined. This is important in the design consideration of the test rig. The materials used for the fabrication of the test rig were also discussed and analysed. MSC Nastran Patran software was used to analyse the model, which was designed by using SolidWorks 2014 software. Based from the results, there were limitations found from the initial design and the test rig design needs to be improved in order for the test rig to operate properly.
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Design and Testing of an Educational Water Tunnel
NASA Astrophysics Data System (ADS)
Kosaraju, Srinivas
2017-11-01
A new water tunnel is designed and tested for educational and research purposes at Northern Arizona University. The university currently owns an educational wind tunnel with a test section of 12in X 12in X 24in. However, due to limited size of test section and range of Reynolds numbers, its application is currently limited to very few experiments. In an effort to expand the educational and research capabilities, a student team is tasked to design, build and test a water tunnel as a Capstone Senior Design project. The water tunnel is designed to have a test section of 8in X 8in X 36in. and be able to test up to Re = 50E3. Multiple numerical models are used to optimize the flow field inside the test section before building the physical apparatus. The water tunnel is designed to accommodate multiple experiments for drag and lift studies. The built-in die system can deliver up to three different colors to study the streamlines and vortex shedding from the surfaces. During the first phase, a low discharge pump is used to achieve Re = 4E3 to test laminar flows. In the second phase, a high discharge pump will be used to achieve targeted Re = 50E3 to study turbulent flows.
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Alfalfa response to irrigation from limited water supplies
USDA-ARS?s Scientific Manuscript database
A five-year field study (2007-2011) of irrigated alfalfa production with a limited water supply was conducted in southwest Kansas with two years of above-average precipitation, one year of average precipitation, and two years of below-average precipitation. The irrigation treatments were designed to...
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Study design and "evidence" in patient-oriented research.
Concato, John
2013-06-01
Individual studies in patient-oriented research, whether described as "comparative effectiveness" or using other terms, are based on underlying methodological designs. A simple taxonomy of study designs includes randomized controlled trials on the one hand, and observational studies (such as case series, cohort studies, and case-control studies) on the other. A rigid hierarchy of these design types is a fairly recent phenomenon, promoted as a tenet of "evidence-based medicine," with randomized controlled trials receiving gold-standard status in terms of producing valid results. Although randomized trials have many strengths, and contribute substantially to the evidence base in clinical care, making presumptions about the quality of a study based solely on category of research design is unscientific. Both the limitations of randomized trials as well as the strengths of observational studies tend to be overlooked when a priori assumptions are made. This essay presents an argument in support of a more balanced approach to evaluating evidence, and discusses representative examples from the general medical as well as pulmonary and critical care literature. The simultaneous consideration of validity (whether results are correct "internally") and generalizability (how well results apply to "external" populations) is warranted in assessing whether a study's results are accurate for patients likely to receive the intervention-examining the intersection of clinical and methodological issues in what can be called a medicine-based evidence approach. Examination of cause-effect associations in patient-oriented research should recognize both the strengths and limitations of randomized trials as well as observational studies.
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Dose-finding design for multi-drug combinations
Wages, Nolan A; Conaway, Mark R; O'Quigley, John
2012-01-01
Background Most of the current designs used for Phase I dose finding trials in oncology will either involve only a single cytotoxic agent or will impose some implicit ordering among the doses. The goal of the studies is to estimate the maximum tolerated dose (MTD), the highest dose that can be administered with an acceptable level of toxicity. A key working assumption of these methods is the monotonicity of the dose–toxicity curve. Purpose Here we consider situations in which the monotonicity assumption may fail. These studies are becoming increasingly common in practice, most notably, in phase I trials that involve combinations of agents. Our focus is on studies where there exist pairs of treatment combinations for which the ordering of the probabilities of a dose-limiting toxicity cannot be known a priori. Methods We describe a new dose-finding design which can be used for multiple-drug trials and can be applied to this kind of problem. Our methods proceed by laying out all possible orderings of toxicity probabilities that are consistent with the known orderings among treatment combinations and allowing the continual reassessment method (CRM) to provide efficient estimates of the MTD within these orders. The design can be seen to simplify to the CRM when the full ordering is known. Results We study the properties of the design via simulations that provide comparisons to the Bayesian approach to partial orders (POCRM) of Wages, Conaway, and O'Quigley. The POCRM was shown to perform well when compared to other suggested methods for partial orders. Therefore, we comapre our approach to it in order to assess the performance of the new design. Limitations A limitation concerns the number of possible orders. There are dose-finding studies with combinations of agents that can lead to a large number of possible orders. In this case, it may not be feasible to work with all possible orders. Conclusions The proposed design demonstrates the ability to effectively estimate MTD combinations in partially ordered dosefinding studies. Because it relaxes the monotonicity assumption, it can be considered a multivariate generalization of the CRM. Hence, it can serve as a link between single and multiple-agent dosefinding trials. PMID:21652689
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Landsverk, John; Brown, C Hendricks; Rolls Reutz, Jennifer; Palinkas, Lawrence; Horwitz, Sarah McCue
2011-01-01
Implementation science is an emerging field of research with considerable penetration in physical medicine and less in the fields of mental health and social services. There remains a lack of consensus on methodological approaches to the study of implementation processes and tests of implementation strategies. This paper addresses the need for methods development through a structured review that describes design elements in nine studies testing implementation strategies for evidence-based interventions addressing mental health problems of children in child welfare and child mental health settings. Randomized trial designs were dominant with considerable use of mixed method designs in the nine studies published since 2005. The findings are discussed in reference to the limitations of randomized designs in implementation science and the potential for use of alternative designs.
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NASA Propulsion Concept Studies and Risk Reduction Activities for Resource Prospector Lander
NASA Technical Reports Server (NTRS)
Trinh, Huu P.; Williams, Hunter; Burnside, Chris
2015-01-01
The trade study has led to the selection of propulsion concept with the lowest cost and net lowest risk -Government-owned, flight qualified components -Meet mission requirements although the configuration is not optimized. Risk reduction activities have provided an opportunity -Implement design improvements while development with the early-test approach. -Gain knowledge on the operation and identify operation limit -Data to anchor analytical models for future flight designs; The propulsion system cold flow tests series have provided valuable data for future design. -The pressure surge from the system priming and waterhammer within component operation limits. -Enable to optimize the ullage volume to reduce the propellant tank mass; RS-34 hot fire tests have successfully demonstrated of using the engines for the RP mission -No degradation of performance due to extended storage life of the hardware. -Enable to operate the engine for RP flight mission scenarios, outside of the qualification regime. -Provide extended data for the thermal and GNC designs. Significant progress has been made on NASA propulsion concept design and risk reductions for Resource Prospector lander.
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Block 2 SRM conceptual design studies. Volume 1, Book 1: Conceptual design package
NASA Technical Reports Server (NTRS)
Smith, Brad; Williams, Neal; Miller, John; Ralston, Joe; Richardson, Jennifer; Moore, Walt; Doll, Dan; Maughan, Jeff; Hayes, Fred
1986-01-01
The conceptual design studies of a Block 2 Solid Rocket Motor (SRM) require the elimination of asbestos-filled insulation and was open to alternate designs, such as case changes, different propellants, modified burn rate - to improve reliability and performance. Limitations were placed on SRM changes such that the outside geometry should not impact the physical interfaces with other Space Shuttle elements and should have minimum changes to the aerodynamic and dynamic characteristics of the Space Shuttle vehicle. Previous Space Shuttle SRM experience was assessed and new design concepts combined to define a valid approach to assured flight success and economic operation of the STS. Trade studies, preliminary designs, analyses, plans, and cost estimates are documented.
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Evaluation of Geometric Design Needs of Freeway Systems Based on Traffic and Geometric Data
DOT National Transportation Integrated Search
2013-10-20
In Las Vegas, Nevada, the increased traffic competes for the limited spaces available in the freeway system and thus reduces safety performance. This study identified geometric design issues on freeway systems in Las Vegas, Nevada, based on available...
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Denoising Sparse Images from GRAPPA using the Nullspace Method (DESIGN)
Weller, Daniel S.; Polimeni, Jonathan R.; Grady, Leo; Wald, Lawrence L.; Adalsteinsson, Elfar; Goyal, Vivek K
2011-01-01
To accelerate magnetic resonance imaging using uniformly undersampled (nonrandom) parallel imaging beyond what is achievable with GRAPPA alone, the Denoising of Sparse Images from GRAPPA using the Nullspace method (DESIGN) is developed. The trade-off between denoising and smoothing the GRAPPA solution is studied for different levels of acceleration. Several brain images reconstructed from uniformly undersampled k-space data using DESIGN are compared against reconstructions using existing methods in terms of difference images (a qualitative measure), PSNR, and noise amplification (g-factors) as measured using the pseudo-multiple replica method. Effects of smoothing, including contrast loss, are studied in synthetic phantom data. In the experiments presented, the contrast loss and spatial resolution are competitive with existing methods. Results for several brain images demonstrate significant improvements over GRAPPA at high acceleration factors in denoising performance with limited blurring or smoothing artifacts. In addition, the measured g-factors suggest that DESIGN mitigates noise amplification better than both GRAPPA and L1 SPIR-iT (the latter limited here by uniform undersampling). PMID:22213069
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48 CFR 1336.609-1 - Design within funding limitations.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Design within funding limitations. 1336.609-1 Section 1336.609-1 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE... Services 1336.609-1 Design within funding limitations. The designee authorized to make the determination...
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10 CFR Appendix A to Subpart D of... - Categorical Exclusions Applicable to General Agency Actions
Code of Federal Regulations, 2012 CFR
2012-01-01
... agreements for energy research and development A1Routine DOE business actions Routine actions necessary to... dissemination Information gathering (including, but not limited to, literature surveys, inventories, site visits... (including, but not limited to, conceptual design, feasibility studies, and analytical energy supply and...
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10 CFR Appendix A to Subpart D of... - Categorical Exclusions Applicable to General Agency Actions
Code of Federal Regulations, 2014 CFR
2014-01-01
... International agreements for energy research and development A1 Routine DOE business actions Routine actions... dissemination Information gathering (including, but not limited to, literature surveys, inventories, site visits... (including, but not limited to, conceptual design, feasibility studies, and analytical energy supply and...
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10 CFR Appendix A to Subpart D of... - Categorical Exclusions Applicable to General Agency Actions
Code of Federal Regulations, 2013 CFR
2013-01-01
... agreements for energy research and development A1Routine DOE business actions Routine actions necessary to... dissemination Information gathering (including, but not limited to, literature surveys, inventories, site visits... (including, but not limited to, conceptual design, feasibility studies, and analytical energy supply and...
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ERIC Educational Resources Information Center
Misra, Anjali; Schloss, Patrick J.
1989-01-01
The critical analysis of 23 studies using respondent techniques for the reduction of excessive emotional reactions in school children focuses on research design, dependent variables, independent variables, component analysis, and demonstrations of generalization and maintenance. Results indicate widespread methodological flaws that limit the…
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ERIC Educational Resources Information Center
Moore, Jacob; Williams, Christopher B.; North, Christopher; Johri, Aditya; Paretti, Marie
2015-01-01
Traditional instructional materials such as textbooks contain significant educational content, but the navigational mechanisms to access that content are limited and, more importantly, not designed with learning in mind. To address this gap, we present the Adaptive Map, a novel organization and navigation tool designed to help students better…
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Design and Usability Testing of an mHealth Application for Midwives in Rural Ghana
ERIC Educational Resources Information Center
Velez, Olivia
2011-01-01
Midwives in Ghana provide the majority of rural primary and maternal healthcare services, but have limited access to data for decision making and knowledge work. Few mobile health (mHealth) applications have been designed for midwives. The study purpose was to design and test an mHealth application (mClinic) that can improve data access and reduce…
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Acoustic Treatment Design Scaling Methods. Volume 1; Overview, Results, and Recommendations
NASA Technical Reports Server (NTRS)
Kraft, R. E.; Yu, J.
1999-01-01
Scale model fan rigs that simulate new generation ultra-high-bypass engines at about 1/5-scale are achieving increased importance as development vehicles for the design of low-noise aircraft engines. Testing at small scale allows the tests to be performed in existing anechoic wind tunnels, which provides an accurate simulation of the important effects of aircraft forward motion on the noise generation. The ability to design, build, and test miniaturized acoustic treatment panels on scale model fan rigs representative of the fullscale engine provides not only a cost-savings, but an opportunity to optimize the treatment by allowing tests of different designs. The primary objective of this study was to develop methods that will allow scale model fan rigs to be successfully used as acoustic treatment design tools. The study focuses on finding methods to extend the upper limit of the frequency range of impedance prediction models and acoustic impedance measurement methods for subscale treatment liner designs, and confirm the predictions by correlation with measured data. This phase of the program had as a goal doubling the upper limit of impedance measurement from 6 kHz to 12 kHz. The program utilizes combined analytical and experimental methods to achieve the objectives.
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48 CFR 436.609-1 - Design within funding limitations.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false Design within funding limitations. 436.609-1 Section 436.609-1 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE... 436.609-1 Design within funding limitations. (a) Should the head of the contracting activity appoint a...
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Practical Guidelines for Evaluating Sampling Designs in Survey Studies.
ERIC Educational Resources Information Center
Fan, Xitao; Wang, Lin
The popularity of sample surveys in evaluation and research makes it necessary for consumers to tell a good survey from a poor one. Several sources were identified that gave advice on how to evaluate a sample design used in a survey study. The sources are either too limited or too extensive to be useful practically. The purpose of this paper is to…
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Integrated source and channel encoded digital communication system design study
NASA Technical Reports Server (NTRS)
Huth, G. K.; Trumpis, B. D.; Udalov, S.
1975-01-01
Various aspects of space shuttle communication systems were studied. The following major areas were investigated: burst error correction for shuttle command channels; performance optimization and design considerations for Costas receivers with and without bandpass limiting; experimental techniques for measuring low level spectral components of microwave signals; and potential modulation and coding techniques for the Ku-band return link. Results are presented.
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Health literacy and patient web portals.
Coughlin, Steven S; Stewart, Jessica L; Young, Lufei; Heboyan, Vahé; De Leo, Gianluca
2018-05-01
There is limited evidence about the association between health literacy and use of patient web portals in patients with chronic illnesses. The objective of this review was to learn more about health literacy and use of patient web portals. Bibliographic searches were conducted in PubMed and CINAHL using relevant MeSH search terms and Boolean algebra commands. Qualitative studies and studies with a cross-sectional, cohort, or pre-/post-test design have shown that persons with limited health literacy are less likely to use patient web portals, although there is inconsistency in the association across studies. The conflicting findings may be partially due to racial and ethnic differences in health literacy or level of comfort in sharing private health information using mobile technologies. Several opportunities exist to improve the usability and acceptability of web portals for patients with limited health literacy including enhancements in the design of the portals, patient and provider education and training, and engagement of proxies such as caregivers and close family members. Copyright © 2018 Elsevier B.V. All rights reserved.
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Medication safety research by observational study design.
Lao, Kim S J; Chui, Celine S L; Man, Kenneth K C; Lau, Wallis C Y; Chan, Esther W; Wong, Ian C K
2016-06-01
Observational studies have been recognised to be essential for investigating the safety profile of medications. Numerous observational studies have been conducted on the platform of large population databases, which provide adequate sample size and follow-up length to detect infrequent and/or delayed clinical outcomes. Cohort and case-control are well-accepted traditional methodologies for hypothesis testing, while within-individual study designs are developing and evolving, addressing previous known methodological limitations to reduce confounding and bias. Respective examples of observational studies of different study designs using medical databases are shown. Methodology characteristics, study assumptions, strengths and weaknesses of each method are discussed in this review.
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Mass of materials: the impact of designers on construction ergonomics.
Smallwood, John
2012-01-01
Many construction injuries are musculoskeletal related in the form of sprains and strains arising from the handling of materials, which are specified by designers. The paper presents the results of a study conducted among delegates attending two 'designing for H&S' (DfH&S) seminars using a questionnaire. The salient findings include: the level of knowledge relative to the mass and density of materials is limited; designers generally do not consider the mass and density of materials when designing structures and elements and specifying materials; to a degree designers appreciate that the mass and density of materials impact on construction ergonomics; designers rate their knowledge of the mass and density of materials as limited, and designers appreciate the potential of the consideration of the mass and density of materials to contribute to an improvement in construction ergonomics. Conclusions include: designers lack the requisite knowledge relative to the mass and density of materials; designers are thus precluded from conducting optimum design hazard identification and risk assessments, and tertiary built environment designer education does not enlighten designers relative to construction ergonomics. Recommendations include: tertiary built environment designer education should construction ergonomics; professional associations should raise the level of awareness relative to construction ergonomics, and design practices should include a category 'mass and density of materials' in their practice libraries.
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NASA Technical Reports Server (NTRS)
Sullivan, Roy M.; Palko, Joseph L.; Tornabene, Robert T.; Bednarcyk, Brett A.; Powers, Lynn M.; Mital, Subodh K.; Smith, Lizalyn M.; Wang, Xiao-Yen J.; Hunter, James E.
2006-01-01
A series of engineering analysis studies were conducted to investigate the potential application of nanoclay-enhanced graphite/epoxy composites and polymer cross-linked silica aerogels in cryogenic hydrogen storage tank designs. This assessment focused on the application of these materials in spherical tank designs for unmanned aeronautic vehicles with mission durations of 14 days. Two cryogenic hydrogen tank design concepts were considered: a vacuum-jacketed design and a sandwiched construction with an aerogel insulating core. Analyses included thermal and structural analyses of the tank designs as well as an analysis of hydrogen diffusion to specify the material permeability requirements. The analyses also provided material property targets for the continued development of cross-linked aerogels and nanoclay-enhanced graphite/epoxy composites for cryogenic storage tank applications. The results reveal that a sandwiched construction with an aerogel core is not a viable design solution for a 14-day mission. A vacuum-jacketed design approach was shown to be far superior to an aerogel. Aerogel insulation may be feasible for shorter duration missions. The results also reveal that the application of nanoclay-enhanced graphite/epoxy should be limited to the construction of outer tanks in a vacuum-jacketed design, since a graphite/epoxy inner tank does not provide a significant weight savings over aluminum and since the ability of nanoclay-enhanced graphite/epoxy to limit hydrogen permeation is still in question.
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ERIC Educational Resources Information Center
Barton, Marlin C.; And Others
An exploratory study of a prison community is presented. The study employed a three-phase design: (1) a pre-survey of the prison community, (2) limited intervention, based on findings of the pre-survey, and (3) a post-survey to determine effects of intervention and to validate findings of the pre-survey for which no intervention had been designed.…
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Seismic design repair and retrofit strategies for steel roof deck diaphragms
NASA Astrophysics Data System (ADS)
Franquet, John-Edward
Structural engineers will often rely on the roof diaphragm to transfer lateral seismic loads to the bracing system of single-storey structures. The implementation of capacity-based design in the NBCC 2005 has caused an increase in the diaphragm design load due to the need to use the probable capacity of the bracing system, thus resulting in thicker decks, closer connector patterns and higher construction costs. Previous studies have shown that accounting for the in-plane flexibility of the diaphragm when calculating the overall building period can result in lower seismic forces and a more cost-efficient design. However, recent studies estimating the fundamental period of single storey structures using ambient vibration testing showed that the in-situ approximation was much shorter than that obtained using analytical means. The difference lies partially in the diaphragm stiffness characteristics which have been shown to decrease under increasing excitation amplitude. Using the diaphragm as the energy-dissipating element in the seismic force resisting system has also been investigated as this would take advantage of the diaphragm's ductility and limited overstrength; thus, lower capacity based seismic forces would result. An experimental program on 21.0m by 7.31m diaphragm test specimens was carried out so as to investigate the dynamic properties of diaphragms including the stiffness, ductility and capacity. The specimens consisted of 20 and 22 gauge panels with nailed frame fasteners and screwed sidelap connections as well a welded and button-punch specimen. Repair strategies for diaphragms that have previously undergone inelastic deformations were devised in an attempt to restitute the original stiffness and strength and were then experimentally evaluated. Strength and stiffness experimental estimations are compared with those predicted with the Steel Deck Institute (SDI) method. A building design comparative study was also completed. This study looks at the difference in design and cost yielded by previous and current design practice with EBF braced frames. Two alternate design methodologies, where the period is not restricted by code limitations and where the diaphragm force is limited to the equivalent shear force calculated with RdR o = 1.95, are also used for comparison. This study highlights the importance of incorporating the diaphragm stiffness in design and the potential cost savings.
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Preliminary design of a mini-Brayton Compressor-Alternator-Turbine (CAT)
NASA Technical Reports Server (NTRS)
1973-01-01
The preliminary design of a mini-Brayton compressor-alternator-turbine system is discussed. The program design goals are listed. The optimum system characteristics over the entire range of power output were determined by performing a wide-range parametric study. The ability to develop the required components to the degree necessary within the limitations of present technology is evaluated. The sensitivity of the system to various individual design parameters was analyzed.
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SUSTAINABLE ENERGY SYSTEMS DESIGN FOR A TRIBAL VILLAGE IN INDIA
Lab testing and limited field testing revealed the effectiveness of the following products designed in this study:Some design considerations for solar-powered aircraftNASA Technical Reports Server (NTRS)
Phillips, W. H.
1980-01-01
Performance and operating characteristics are presented for a solar powered aircraft intended to remain aloft for long periods. The critical technologies which limit the performance are identified. By using the techniques presented, the effects of variation in the system parameters are studied. Practical design consideration are discussed.
Early detection network design and search strategy issues
We conducted a series of field and related modeling studies (2005-2012) to evaluate search strategies for Great Lakes coastal ecosystems that are at risk of invasion by non-native aquatic species. In developing a network, we should design to achieve an acceptable limit of detect...
EVALUATION OF AN ADVANCED ENGINEERING TEST REACTOR DESIGN
DOE Office of Scientific and Technical Information (OSTI.GOV)
McVey, M.; Bradfute, J.O.; Buck, K.E.
1958-07-15
The scope of the study was primarily concerned with optimization of the geometrical and core-composition variables to achieve maximum flux in the loop region per unit core power without exceeding heat transfer and other engineering limitations. Centain other design questions are to be investigated. (A.C.)
Design study for electronic system for Jupiter Orbit Probe (JOP)
NASA Technical Reports Server (NTRS)
Elero, B. P., Jr.; Carignan, G. R.
1978-01-01
The conceptual design of the Jupiter probe spectrometer is presented. Block and circuit diagrams are presented along with tabulated parts lists. Problem areas are considered to be (1) the schedule, (2) weight limitations for the electronic systems, and (3) radiation hardness of the electronic devices.
Progress toward Topology Optimization (TO) for Additive Manufacturing (AM) and Fatigue
2017-06-15
traditional manufacturing processes due to cost, tool-path constraints, or operator limitations. While AM significantly widens the design space for TO... manufacturing constraints and limitations remain1 and should be addressed in the design process. An objective of this work is to consider manufacturing ...account for AM limitations within the design . The limitations of interest in this work are the production of support material and enclosed pores. Both
NASA Astrophysics Data System (ADS)
Kaur, Parneet; Singh, Sukhwinder; Garg, Sushil; Harmanpreet
2010-11-01
In this paper we study about classification algorithms for farm DSS. By applying classification algorithms i.e. Limited search, ID3, CHAID, C4.5, Improved C4.5 and One VS all Decision Tree on common data set of crop with specified class, results are obtained. The tool used to derive results is SPINA. The graphical results obtained from tool are compared to suggest best technique to develop farm Decision Support System. This analysis would help to researchers to design effective and fast DSS for farmer to take decision for enhancing their yield.
A Strategic Approach to Medical Care for Exploration Missions
NASA Technical Reports Server (NTRS)
Canga, Michael A.; Shah, Ronak V.; Mindock, Jennifer A.; Antonsen, Erik L.
2016-01-01
Exploration missions will present significant new challenges to crew health, including effects of variable gravity environments, limited communication with Earth-based personnel for diagnosis and consultation for medical events, limited resupply, and limited ability for crew return. Providing health care capabilities for exploration class missions will require system trades be performed to identify a minimum set of requirements and crosscutting capabilities, which can be used in design of exploration medical systems. Medical data, information, and knowledge collected during current space missions must be catalogued and put in formats that facilitate querying and analysis. These data are used to inform the medical research and development program through analysis of risk trade studies between medical care capabilities and system constraints such as mass, power, volume, and training. Medical capability as a quantifiable variable is proposed as a surrogate risk metric and explored for trade space analysis that can improve communication between the medical and engineering approaches to mission design. The resulting medical system design approach selected will inform NASA mission architecture, vehicle, and subsystem design for the next generation of spacecraft.
Investigation of Microcavitation-Induced Effects using in Vitro Models for Traumatic Brain Injury
2016-08-25
four MOSFET switches (IXFB38N I OOQ2) stacking in series . The designing details of such stacking circuit can be found in [25] . In brief, the gate... time of the mechanical vibration of the piezotransducer. The on- time in this study was limited to ~2 s. B. Microbubble chamber design Rev. Sci...60 s. This long collapse time may be favored for biological studies where the observation of time evolution is of essence. We purposely designed the
CubeSat Material Limits For Design for Demise
NASA Technical Reports Server (NTRS)
Kelley, R. L.; Jarkey, D. R.
2014-01-01
The CubeSat form factor of nano-satellite (a satellite with a mass between one and ten kilograms) has grown in popularity due to their ease of construction and low development and launch costs. In particular, their use as student led payload design projects has increased due to the growing number of launch opportunities. CubeSats are often deployed as secondary or tertiary payloads on most US launch vehicles or they may be deployed from the ISS. The focus of this study will be on CubeSats launched from the ISS. From a space safety standpoint, the development and deployment processes for CubeSats differ significantly from that of most satellites. For large satellites, extensive design reviews and documentation are completed, including assessing requirements associated with reentry survivability. Typical CubeSat missions selected for ISS deployment have a less rigorous review process that may not evaluate aspects beyond overall design feasibility. CubeSat design teams often do not have the resources to ensure their design is compliant with reentry risk requirements. A study was conducted to examine methods to easily identify the maximum amount of a given material that can be used in the construction of a CubeSats without posing harm to persons on the ground. The results demonstrate that there is not a general equation or relationship that can be used for all materials; instead a limiting value must be defined for each unique material. In addition, the specific limits found for a number of generic materials that have been previously used as benchmarking materials for reentry survivability analysis tool comparison will be discussed.
CubeSat Material Limits for Design for Demise
NASA Technical Reports Server (NTRS)
Kelley, R. L.; Jarkey, D. R.
2014-01-01
The CubeSat form factor of nano-satellite (a satellite with a mass between one and ten kilograms) has grown in popularity due to their ease of construction and low development and launch costs. In particular, their use as student led payload design projects has increased due to the growing number of launch opportunities. CubeSats are often deployed as secondary or tertiary payloads on most US launch vehicles or they may be deployed from the ISS. The focus of this study will be on CubeSats launched from the ISS. From a space safety standpoint, the development and deployment processes for CubeSats differ significantly from that of most satellites. For large satellites, extensive design reviews and documentation are completed, including assessing requirements associated with re-entry survivability. Typical CubeSat missions selected for ISS deployment have a less rigorous review process that may not evaluate aspects beyond overall design feasibility. CubeSat design teams often do not have the resources to ensure their design is compliant with re-entry risk requirements. A study was conducted to examine methods to easily identify the maximum amount of a given material that can be used in the construction of a CubeSats without posing harm to persons on the ground. The results demonstrate that there is not a general equation or relationship that can be used for all materials; instead a limiting value must be defined for each unique material. In addition, the specific limits found for a number of generic materials that have been previously used as benchmarking materials for re-entry survivability analysis tool comparison will be discussed.
Preschool Age Populations Research Needs - NCS Dietary Assessment Literature Review
Drawing conclusions from the validation studies on preschool populations discussed in this chapter is difficult because of the varied study designs, the relatively small study populations, and limited number of studies on each dietary assessment method.
Unique Study Designs in Nephrology: N-of-1 Trials and Other Designs.
Samuel, Joyce P; Bell, Cynthia S
2016-11-01
Alternatives to the traditional parallel-group trial design may be required to answer clinical questions in special populations, rare conditions, or with limited resources. N-of-1 trials are a unique trial design which can inform personalized evidence-based decisions for the patient when data from traditional clinical trials are lacking or not generalizable. A concise overview of factorial design, cluster randomization, adaptive designs, crossover studies, and n-of-1 trials will be provided along with pertinent examples in nephrology. The indication for analysis strategies such as equivalence and noninferiority trials will be discussed, as well as analytic pitfalls. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.
Preliminary design study of an alternate heat source assembly for a Brayton isotope power system
NASA Technical Reports Server (NTRS)
Strumpf, H. J.
1978-01-01
Results are presented for a study of the preliminary design of an alternate heat source assembly (HSA) intended for use in the Brayton isotope power system (BIPS). The BIPS converts thermal energy emitted by a radioactive heat source into electrical energy by means of a closed Brayton cycle. A heat source heat exchanger configuration was selected and optimized. The design consists of a 10 turn helically wound Hastelloy X tube. Thermal analyses were performed for various operating conditions to ensure that post impact containment shell (PICS) temperatures remain within specified limits. These limits are essentially satisfied for all modes of operation except for the emergency cooling system for which the PICS temperatures are too high. Neon was found to be the best choice for a fill gas for auxiliary cooling system operation. Low cycle fatigue life, natural frequency, and dynamic loading requirements can be met with minor modifications to the existing HSA.
A health literacy and usability heuristic evaluation of a mobile consumer health application.
Monkman, Helen; Kushniruk, Andre
2013-01-01
Usability and health literacy are two critical factors in the design and evaluation of consumer health information systems. However, methods for evaluating these two factors in conjunction remain limited. This study adapted a set of existing guidelines for the design of consumer health Web sites into evidence-based evaluation heuristics tailored specifically for mobile consumer health applications. In order to test the approach, a mobile consumer health application (app) was then evaluated using these heuristics. In addition to revealing ways to improve the usability of the system, this analysis identified opportunities to augment the content to make it more understandable by users with limited health literacy. This study successfully demonstrated the utility of converting existing design guidelines into heuristics for the evaluation of usability and health literacy. The heuristics generated could be applied for assessing and revising other existing consumer health information systems.
Balloon-borne 3-meter telescope for far-infrared and submillimeter astronomy
NASA Technical Reports Server (NTRS)
Fazio, G. G.
1986-01-01
The gimbal design was studied and revised to eliminate the alignment and limited rotation problems inherent in the flex-pivot design. A new design using ball-bearings to replace the flex-pivot was defined and its performance analyzed. An error analysis for the entire gondola pointing system was also prepared. Mirror development and the test program using mirror test blanks from Dornier were continued.
76 FR 64788 - Airworthiness Directives; BAE SYSTEMS (Operations) Limited Model 4101 Airplanes
Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-19
... ``Certification Maintenance Requirements'', and, --05-10-30 ``Critical Design Configuration Control Limitations... Limitations''; 05-10-20, ``Certification Maintenance Requirements''; and 05-10-30, ``Critical Design... BAE Systems (Operations) Limited Jetstream Series 4100 AMM, Revision 35, dated February 15, 2011. We...
ERIC Educational Resources Information Center
Pitner, Nancy J.; Russell, James S.
1986-01-01
This paper critically reviews studies of administrator work activities which follow the work of Henry Mintzberg (1973), concentrating on these shortcomings of the method: (1) procedural difficulties in coding; (2) design limitations of classifying activities; (3) inadequate testing of Mintzberg's hypotheses; and (4) failure to explore antecedents…
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NASA Technical Reports Server (NTRS)
Hyer, Michael W.; Charette, Robert F.
1988-01-01
Further studies to determine the potential for using a curvilinear fiber format in the design of composite laminates are reported. The curvilinear format is in contrast to the current practice of having the fibers aligned parallel to each other and in a straight line. The problem of a plate with a central circular hole is used as a candidate problem for this study. The study concludes that for inplane tensile loading the curvilinear format is superior. The limited results to date on compression buckling loads indicate that the curvilinear designs are poorer in resistant buckling. However, for the curvilinear design of interest, the reduction in buckling load is minimal and so overall there is a gain in considering the curvilinear design.
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Davis, William E; Hicks, Joshua A
2013-12-01
Four studies tested the hypothesis that limited time perceptions are associated with lower levels of hope, and that this effect is buffered by high levels of authenticity. Study 1 (n = 256) utilized a cross-sectional design in which participants completed dispositional measures of time perspective, hope, and authenticity. Three subsequent studies tested our hypothesis experimentally. In a pilot study (n = 124), participants reported their perceived authenticity, future time perspective (FTP) was manipulated (limited vs. open-ended), and state hope was assessed. Study 2 (n = 156) introduced a new manipulation of FTP, and Study 3 (n = 242) replicated Study 2 with the addition of a neutral control condition. Across all studies, individuals who perceived time as limited reported lower levels of hope relative to those who perceived time as open-ended (or those in a neutral control condition), but, importantly, this effect was attenuated for highly authentic individuals.
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Andreuccetti, Gabriel; Ye, Yu; Kang, Jaewook; Korcha, Rachael; Witbrodt, Jane A.; Carvalho, Heraclito B.; Cherpitel, Cheryl J.
2018-01-01
Recent evidence has indicated that cannabis use before driving is associated with a modest but increased risk for traffic-related injuries. However, the question of whether recent cannabis use is associated with a greater risk for other types of injuries remains unanswered. Aiming to understand better how acute cannabis use might affect the risk for all causes of injury, we have summarized the limited data available in the literature on the risk of non-traffic injuries associated with recent cannabis use. Very few studies were able to provide estimate risks for all injuries or injuries other than those related to road traffic injuries, with the limited evidence available showing mixed findings. The only significant risk found (in only one study) suggests an inverse association between all injuries and cannabis use. Study designs are limited, and the majority of studies have neither data on acute cannabis use among injured individuals nor a valid control group for estimating injury risk attributable to cannabis. In conclusion, studies of the association between cannabis and non-traffic injuries present several limitations, particularly regarding sampling strategies, injury risk assessment for different causes of injury, and a dose-response risk relationship with injury. Further studies, incorporating better design for different causes of injury and drug testing, are required to reach firmer conclusions on the association between cannabis use and non-traffic injury risk. PMID:29456273
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Fuzzy analysis of serviceability limit state of slender steel beam under bending
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kala, Zdeněk; Valeš, Jan
In the present paper, deformations of a beam under equal end moments solved with influence of lateral buckling are studied. It has been found by numerical studies that the lateral deflection of slender beam under major axis bending can be relatively high.The acceptability of high values of lateral deflections within the framework of serviceability limit state is discussed. In the next part of the paper, the limit value of maximum deflection was introduced as a fuzzy number. The fuzzy analysis of the maximum moment which causes the maximum deflection was carried out. The slendernesses of beams for which the serviceabilitymore » limit state is the limiting state for design were identified.« less
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Roe, Justin W G; Carding, Paul N; Dwivedi, Raghav C; Kazi, Rehan A; Rhys-Evans, Peter H; Harrington, Kevin J; Nutting, Christopher M
2010-10-01
A systematic review to establish what evidence is available for swallowing outcomes following IMRT for head and neck cancer. Online electronic databases were searched to identify papers published in English from January 1998 to December 2009. Papers were independently appraised by two reviewers for methodological quality, method of swallowing evaluation and categorized according to the World Health Organisation's International Classification of Health Functions. The impact of radiation dose to dysphagia aspiration risk structures (DARS) was also evaluated. Sixteen papers met the inclusion criteria. The literature suggests that limiting the radiation dose to certain structures may result in favourable swallowing outcomes. Methodological limitations included variable assessment methods and outcome measures and heterogeneity of patients. There are only limited prospective data, especially where pre-treatment measures have been taken and compared to serial post-treatment assessment. Few studies have investigated the impact of IMRT on swallow function and the impact on everyday life. Initial studies have reported potential benefits but are limited in terms of study design and outcome data. Further well designed, prospective, longitudinal swallowing studies including multidimensional evaluation methods are required to enable a more comprehensive understanding of dysphagia complications and inform pre-treatment counselling and rehabilitation planning. Copyright © 2010 Elsevier Ltd. All rights reserved.
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Limitations of self-care in reducing the risk of lymphedema: supportive-educative systems.
Armer, Jane M; Brooks, Constance W; Stewart, Bob R
2011-01-01
The purpose of this study was to examine patient perceptions of limitations related to self-care measures to reduce lymphedema risk following breast cancer surgery. Secondary analysis of survey data from a companion study to a study piloting a behavioral-educational intervention was conducted to examine the specific limitations in performing lymphedema risk-reduction self-care measures. Findings suggest a more comprehensive approach is needed if patients are to engage in self-care actions to reduce lymphedema risk. Understanding the concepts of self-care and personal support interventions that include motivational interviewing can help nurses design supportive-educative care systems that assist patients in overcoming limitations in the estimative, transitional, and productive phases of self-care necessary to reduce lymphedema risk.
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Split-mouth design in Paediatric Dentistry clinical trials.
Pozos-Guillén, A; Chavarría-Bolaños, D; Garrocho-Rangel, A
2017-03-01
The aim of this article was to describe the essential concepts of the split-mouth design, its underlying assumptions, advantages, limitations, statistical considerations, and possible applications in Paediatric Dentistry clinical investigation. In Paediatric Dentistry clinical investigation, and as part of randomised controlled trials, the split-mouth design is commonly used. The design is characterised by subdividing the child's dentition into halves (right and left), where two different treatment modalities are assigned to one side randomly, in order to allow further outcome evaluation. Each participant acts as their own control by making within- patient rather than between-patient comparisons, thus diminishing inter-subject variability and increasing study accuracy and power. However, the main problem with this design comprises the potential contamination of the treatment effect from one side to the other, or the "carry-across effect"; likewise, this design is not indicated when the oral disease to be treated is not symmetrically distributed (e.g. severity) in the mouth of children. Thus, in spite of its advantages, the split-mouth design can only be applied in a limited number of strictly selected cases. In order to obtain valid and reliable data from split mouth design studies, it is necessary to evaluate the risk of carry-across effect as well as to carefully analise and select adequate inclusion criteria, sample-size calculation and method of statistical analysis.
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NASA Technical Reports Server (NTRS)
Rouse, Marshall; Ambur, Damodar R.; Bodine, Jerry; Dopker, Bernhard
1997-01-01
The results from an experimental and analytical study of a composite sandwich fuselage side panel for a transport aircraft are presented. The panel has two window cutouts and three frames, and has been evaluated with internal pressure loads that generate biaxial tension loading conditions. Design limit load and design ultimate load tests have been performed on the graphite-epoxy sandwich panel with the middle frame removed to demonstrate the suitability of this two-frame design for supporting the prescribed biaxial loading conditions with twice the initial frame spacing of 20 inches. The two-frame panel was damaged by cutting a notch that originates at the edge of a cutout and extends in the panel hoop direction through the window-belt area. This panel with a notch was tested in a combined-load condition to demonstrate the structural damage tolerance at the design limit load condition. The two panel configurations successfully satisfied all design load requirements in the experimental part of the study, and the three-frame and two-frame panel responses are fully explained by the analysis results. The results of this study suggest that there is potential for using sandwich structural concepts with greater than the usual 20-in.-wide frame spacing to further reduce aircraft fuselage structural weight.
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A case study on topology optimized design for additive manufacturing
NASA Astrophysics Data System (ADS)
Gebisa, A. W.; Lemu, H. G.
2017-12-01
Topology optimization is an optimization method that employs mathematical tools to optimize material distribution in a part to be designed. Earlier developments of topology optimization considered conventional manufacturing techniques that have limitations in producing complex geometries. This has hindered the topology optimization efforts not to fully be realized. With the emergence of additive manufacturing (AM) technologies, the technology that builds a part layer upon a layer directly from three dimensional (3D) model data of the part, however, producing complex shape geometry is no longer an issue. Realization of topology optimization through AM provides full design freedom for the design engineers. The article focuses on topologically optimized design approach for additive manufacturing with a case study on lightweight design of jet engine bracket. The study result shows that topology optimization is a powerful design technique to reduce the weight of a product while maintaining the design requirements if additive manufacturing is considered.
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14 CFR 25.937 - Turbopropeller-drag limiting systems.
Code of Federal Regulations, 2013 CFR
2013-01-01
...-drag limiting systems. Turbopropeller power airplane propeller-drag limiting systems must be designed... results in propeller drag in excess of that for which the airplane was designed under § 25.367. Failure of...
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14 CFR 25.937 - Turbopropeller-drag limiting systems.
Code of Federal Regulations, 2012 CFR
2012-01-01
...-drag limiting systems. Turbopropeller power airplane propeller-drag limiting systems must be designed... results in propeller drag in excess of that for which the airplane was designed under § 25.367. Failure of...
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14 CFR 25.937 - Turbopropeller-drag limiting systems.
Code of Federal Regulations, 2011 CFR
2011-01-01
...-drag limiting systems. Turbopropeller power airplane propeller-drag limiting systems must be designed... results in propeller drag in excess of that for which the airplane was designed under § 25.367. Failure of...
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14 CFR 25.937 - Turbopropeller-drag limiting systems.
Code of Federal Regulations, 2010 CFR
2010-01-01
...-drag limiting systems. Turbopropeller power airplane propeller-drag limiting systems must be designed... results in propeller drag in excess of that for which the airplane was designed under § 25.367. Failure of...
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14 CFR 25.937 - Turbopropeller-drag limiting systems.
Code of Federal Regulations, 2014 CFR
2014-01-01
...-drag limiting systems. Turbopropeller power airplane propeller-drag limiting systems must be designed... results in propeller drag in excess of that for which the airplane was designed under § 25.367. Failure of...
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Literature Review of Research on Chronic Pain and Yoga in Military Populations
Miller, Shari; Gaylord, Susan; Buben, Alex; Brintz, Carrie; Rae Olmsted, Kristine; Asefnia, Nakisa; Bartoszek, Michael
2017-01-01
Background: Although yoga is increasingly being provided to active duty soldiers and veterans, studies with military populations are limited and effects on chronic pain are largely unknown. We reviewed the existing body of literature and provide recommendations for future research. Methods: We conducted a literature review of electronic databases (PubMed, PsychINFO, Web of Science, Science Citation Index Expanded, Social Sciences Citation Index, Conference Proceedings Citation Index—Science, and Conference Proceedings Citation Index—Social Science & Humanities). The studies were reviewed for characteristics such as mean age of participants, sample size, yoga type, and study design. Only peer-reviewed studies were included in the review. Results: The search yielded only six studies that examined pain as an outcome of yoga for military populations. With one exception, studies were with veteran populations. Only one study was conducted with Operation Enduring Freedom (OEF) or Operation Iraqi Freedom (OIF) veterans. One study was a randomized controlled trial (RCT). Four of the five studies remaining used pre/post design, while the last study used a post-only design. Conclusions: Studies on the use of yoga to treat chronic pain in military populations are in their infancy. Methodological weaknesses include small sample sizes, a lack of studies with key groups (active duty, OEF/IEF veterans), and use of single group uncontrolled designs (pre/post; post only) for all but one study. Future research is needed to address these methodological limitations and build on this small body of literature. PMID:28930278
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Factors Associated With Exercise Behavior in People With Parkinson Disease
Cavanaugh, James T.; Earhart, Gammon M.; Ford, Matthew P.; Foreman, K. Bo; Fredman, Lisa; Boudreau, Jennifer K.; Dibble, Leland E.
2011-01-01
Background The benefits of exercise for reducing disability in people with Parkinson disease (PD) are becoming more evident. Optimal benefit, however, requires regular and sustained participation. Factors associated with engaging in regular exercise have received little scientific scrutiny in people with PD. Objective The purpose of this study was to explore factors associated with exercise behavior in patients with PD using the International Classification of Functioning, Disability and Health (ICF) as a guiding framework. Design This was a cross-sectional study. Methods The participants in this study were 260 patients with PD from 4 institutions. Participants were designated as “exercisers” or “nonexercisers” based on responses to the Stages of Readiness to Exercise Questionnaire. Exercise status was validated using the Physical Activity Scale for the Elderly and an activity monitor. Factors potentially associated with exercise behavior included measures of body structure and function, activity, participation, environmental factors, and personal factors. Their relative contributions were analyzed using logistic regression and quantified with odds ratios. Results One hundred sixty-four participants (63%) were designated as exercisers. Participants with high self-efficacy were more than twice as likely to engage in regular exercise than those with low self-efficacy (adjusted odds ratio=2.34, 95% confidence interval=1.30–4.23). College educated and older participants also were more likely to exercise. Disabling influences of impairments, activity limitations, and participation restrictions were not associated with exercise behavior. Limitations The cross-sectional nature of the study limited the ability to make causal inferences. Conclusions Self-efficacy, rather than disability, appears to be strongly associated with whether ambulatory, community-dwelling people with PD exercise regularly. The results of this study suggest that physical therapists should include strategies to increase exercise self-efficacy when designing patient intervention programs for patients with PD. PMID:22003171
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A Strategic Approach to Medical Care for Exploration Missions
NASA Technical Reports Server (NTRS)
Antonsen, E.; Canga, M.
2016-01-01
Exploration missions will present significant new challenges to crew health, including effects of variable gravity environments, limited communication with Earth-based personnel for diagnosis and consultation for medical events, limited resupply, and limited ability for crew return. Providing health care capabilities for exploration class missions will require system trades be performed to identify a minimum set of requirements and crosscutting capabilities which can be used in design of exploration medical systems. Current and future medical data, information, and knowledge must be cataloged and put in formats that facilitate querying and analysis. These data may then be used to inform the medical research and development program through analysis of risk trade studies between medical care capabilities and system constraints such as mass, power, volume, and training. These studies will be used to define a Medical Concept of Operations to facilitate stakeholder discussions on expected medical capability for exploration missions. Medical Capability as a quantifiable variable is proposed as a surrogate risk metric and explored for trade space analysis that can improve communication between the medical and engineering approaches to mission design. The resulting medical system approach selected will inform NASA mission architecture, vehicle, and subsystem design for the next generation of spacecraft.
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Field Validation of the Stability Limit of a Multi MW Turbine
NASA Astrophysics Data System (ADS)
Kallesøe, Bjarne S.; Kragh, Knud A.
2016-09-01
Long slender blades of modern multi-megawatt turbines exhibit a flutter like instability at rotor speeds above a critical rotor speed. Knowing the critical rotor speed is crucial to a safe turbine design. The flutter like instability can only be estimated using geometrically non-linear aeroelastic codes. In this study, the estimated rotor speed stability limit of a 7 MW state of the art wind turbine is validated experimentally. The stability limit is estimated using Siemens Wind Powers in-house aeroelastic code, and the results show that the predicted stability limit is within 5% of the experimentally observed limit.
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Fusion reactor blanket/shield design study
NASA Astrophysics Data System (ADS)
Smith, D. L.; Clemmer, R. G.; Harkness, S. D.; Jung, J.; Krazinski, J. L.; Mattas, R. F.; Stevens, H. C.; Youngdahl, C. K.; Trachsel, C.; Bowers, D.
1979-07-01
A joint study of Tokamak reactor first wall/blanket/shield technology was conducted to identify key technological limitations for various tritium breeding blanket design concepts, establishment of a basis for assessment and comparison of the design features of each concept, and development of optimized blanket designs. The approach used involved a review of previously proposed blanket designs, analysis of critical technological problems and design features associated with each of the blanket concepts, and a detailed evaluation of the most tractable design concepts. Tritium breeding blanket concepts were evaluated according to the proposed coolant. The effort concentrated on evaluation of lithium and water cooled blanket designs and helium and molten salt cooled designs. Generalized nuclear analysis of the tritium breeding performance, an analysis of tritium breeding requirements, and a first wall stress analysis were conducted as part of the study. The impact of coolant selection on the mechanical design of a Tokamak reactor was evaluated. Reference blanket designs utilizing the four candidate coolants are presented.
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Design of control-group conditions in clinical trials of behavioral interventions.
Lindquist, Ruth; Wyman, Jean F; Talley, Kristine M C; Findorff, Mary J; Gross, Cynthia R
2007-01-01
To review considerations in the design of placebo (attention) control conditions for community-based clinical trials of health behavior change interventions and to provide practical strategies for the design of control conditions. A well-designed control condition is an essential component of a clinical trial to foster the unambiguous interpretation of study findings. Pitfalls in the design of control conditions in clinical trials of behavioral interventions are identified and strategies to address them are offered. Types of control conditions that have been used in fall prevention trials are described, along with their strengths and weaknesses. The control condition used in the recent fall evaluation and prevention program (FEPP) was designed to overcome limitations of previous trial designs; it is provided to illustrate how to apply specific design principles. Pitfalls in the design of behavioral intervention studies may be avoided with the application of sound design principles. The FEPP active control condition can be used as a model in the design of future studies.
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Investigating rate-limiting barriers to nanoscale nonviral gene transfer with nanobiophotonics
NASA Astrophysics Data System (ADS)
Chen, Hunter H.
Nucleic acids are a novel class of therapeutics poised to address many unmet clinical needs. Safe and efficient delivery remains a significant challenge that has delayed the realization of the full therapeutic potential of nucleic acids. Nanoscale nonviral vectors offer an attractive alternative to viral vectors as natural and synthetic polymers or polypeptides may be rationally designed to meet the unique demands of individual applications. A mechanistic understanding of cellular barriers is necessary to develop guidelines for designing custom gene carriers which are expected to greatly impact this delivery challenge. The work herein focused on the relationships among nanocomplex stability, intracellular trafficking and unpacking kinetics, and DNA degradation. Ultrasensitive nanosensors based on QD-FRET were developed to characterize the biophysical properties of nanocomplexes and study these rate-limiting steps. Quantitative image analysis enabled the distributions of the subpopulation of condensed or released DNA to be determined within the major cellular compartments encountered during gene transfer. The steady state stability and unpacking kinetics within these compartments were found to impact transgene expression, elucidating multiple design strategies to achieve efficient gene transfer. To address enzymatic barriers, a novel two-step QD-FRET nanosensor was developed to analyze unpacking and DNA degradation simultaneously, which has not been accomplished previously. Bioresponsive strategies such as disulfide crosslinking and thermosensitivity were evaluated by QD-FRET and quantitative compartmental analysis as case studies to determine appropriate design specifications for thiolated polymers and thermoresponsive polypeptides. Relevant nanobiophotonic tools were developed as a platform to study major rate-limiting barriers to nanomedicine and demonstrated the feasibility of using mechanistic information gained from these tools to guide the rational design of gene carriers and achieve the desired properties that enable efficient gene transfer.
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Williams, David M; Ussher, Michael; Dunsiger, Shira; Miranda, Robert; Gwaltney, Chad J; Monti, Peter M; Emerson, Jessica
2014-01-01
Aerobic exercise has been proposed as a stand-alone or adjunct smoking cessation treatment, but findings have been mixed. Laboratory studies have shown that individual exercise sessions lead to decreases in withdrawal symptoms and cigarette cravings, but findings are limited by lack of follow-up and artificial settings. On the other hand, smoking cessation treatment RCTs have generally failed to show positive effects of exercise on smoking cessation, but have been plagued by poor and/or unverified compliance with exercise programs. This paper describes the rationale and design for Quit for Health (QFH)--an RCT designed to determine the efficacy of aerobic exercise as an adjunct smoking cessation treatment among women. To overcome limitations of previous research, compliance with the exercise (and wellness contact control) program is incentivized and directly observed, and ecological momentary assessment is used to examine change over time in withdrawal symptoms and cigarette cravings in participants' natural environments. Copyright © 2013 Elsevier Inc. All rights reserved.
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Williams, David M.; Ussher, Michael; Dunsiger, Shira; Miranda, Robert; Gwaltney, Chad J.; Monti, Peter M.; Emerson, Jessica
2013-01-01
Aerobic exercise has been proposed as a stand-alone or adjunct smoking cessation treatment, but findings have been mixed. Laboratory studies have shown that individual exercise sessions lead to decreases in withdrawal symptoms and cigarette cravings, but findings are limited by lack of follow-up and artificial settings. On the other hand, smoking cessation treatment RCTs have generally failed to show positive effects of exercise on smoking cessation, but have been plagued by poor and/or unverified compliance with exercise programs. This paper describes the rationale and design for Quit for Health (QFH)—an RCT designed to determine the efficacy of aerobic exercise as an adjunct smoking cessation treatment among women. To overcome limitations of previous research, compliance with the exercise (and wellness contact control) program is incentivized and directly observed, and ecological momentary assessment is used to examine change over time in withdrawal symptoms and cigarette cravings in participants’ natural environments. PMID:24246818
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Mark DeHart; William Skerjanc; Sean Morrell
2012-06-01
Analysis of the performance of the ATR with a LEU fuel design shows promise in terms of a core design that will yield the same neutron sources in target locations. A proposed integral cladding burnable absorber design appears to meet power profile requirements that will satisfy power distributions for safety limits. Performance of this fuel design is ongoing; the current work is the initial evaluation of the core performance of this fuel design with increasing burnup. Results show that LEU fuel may have a longer lifetime that HEU fuel however, such limits may be set by mechanical performance of themore » fuel rather that available reactivity. Changes seen in the radial fuel power distribution with burnup in LEU fuel will require further study to ascertain the impact on neutron fluxes in target locations. Source terms for discharged fuel have also been studied. By its very nature, LEU fuel produces much more plutonium than is present in HEU fuel at discharge. However, the effect of the plutonium inventory appears to have little affect on radiotoxicity or decay heat in the fuel.« less
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Design and evaluation of a kitchen for persons with visual impairments.
Kutintara, Benjamas; Somboon, Pornpun; Buasri, Virajada; Srettananurak, Metinee; Jedeeyod, Piyanooch; Pornpratoom, Kittikan; Iam-cham, Veraya
2013-03-01
Visually impaired people need skills on daily living, such as cooking, and Ratchasuda College offers independent living training for them. In order to fulfill their needs, a suitable kitchen should be designed with the consideration of their limitations. The objective of this study was to design and evaluate a kitchen for persons with visual impairments. Before designing the kitchen, interviews and an observation were carried out to obtain information on the needs of blind and low vision persons. Consequently, a kitchen model was developed, and it was evaluated by 10 persons with visual impairments. After the design improvement, the kitchen was built and has been routinely used for training persons with visual impairments to prepare meals. Finally, a post-occupancy evaluation of the kitchen was conducted by observing and interviewing both trainers and those with visual impairments during the food preparation training. The results of the study indicated that kitchens for persons with visual impairments should have safety and usability features. The results of the post-occupancy evaluation showed that those who attended cooking courses were able to cook safely in the kitchen. However, the kitchen still had limitations in some features.
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Multi-path transportation futures study: Results from Phase 1
DOE Office of Scientific and Technical Information (OSTI.GOV)
Patterson, Phil; Singh, Margaret; Plotkin, Steve
2007-03-09
This PowerPoint briefing provides documentation and details for Phase 1 of the Multi-Path Transportation Futures Study, which compares alternative ways to make significant reductions in oil use and carbon emissions from U.S. light vehicles to 2050. Phase I, completed in 2006, was a scoping study, aimed at identifying key analytic issues and constructing a study design. The Phase 1 analysis included an evaluation of several pathways and scenarios; however, these analyses were limited in number and scope and were designed to be preliminary.
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Jonsson, B; Martinalbo, J; Pignatti, F
2017-05-01
In the development of highly active anticancer drugs, the European situation may be viewed as paradoxical. Limited data may support marketing authorization, but may be insufficient for the health economic appraisal needed for reimbursement and market uptake. To achieve this, conventional confirmatory studies may be needed. For products of special interest, studies aimed at optimizing cost-effectiveness may be warranted. Efficient designs of studies to meet these objectives constitute challenges to all stakeholders. © 2017 ASCPT.
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Amasya, Gulin; Badilli, Ulya; Aksu, Buket; Tarimci, Nilufer
2016-03-10
With Quality by Design (QbD), a systematic approach involving design and development of all production processes to achieve the final product with a predetermined quality, you work within a design space that determines the critical formulation and process parameters. Verification of the quality of the final product is no longer necessary. In the current study, the QbD approach was used in the preparation of lipid nanoparticle formulations to improve skin penetration of 5-Fluorouracil, a widely-used compound for treating non-melanoma skin cancer. 5-Fluorouracil-loaded lipid nanoparticles were prepared by the W/O/W double emulsion - solvent evaporation method. Artificial neural network software was used to evaluate the data obtained from the lipid nanoparticle formulations, to establish the design space, and to optimize the formulations. Two different artificial neural network models were developed. The limit values of the design space of the inputs and outputs obtained by both models were found to be within the knowledge space. The optimal formulations recommended by the models were prepared and the critical quality attributes belonging to those formulations were assigned. The experimental results remained within the design space limit values. Consequently, optimal formulations with the critical quality attributes determined to achieve the Quality Target Product Profile were successfully obtained within the design space by following the QbD steps. Copyright © 2016 Elsevier B.V. All rights reserved.
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Concept development of a Mach 4 high-speed civil transport
NASA Technical Reports Server (NTRS)
Domack, Christopher S.; Dollyhigh, Samuel M.; Beissner, Fred L., Jr.; Geiselhart, Karl A.; Mcgraw, Marvin E., Jr.; Shields, Elwood W.; Swanson, Edward E.
1990-01-01
A study was conducted to configure and analyze a 250 passenger, Mach 4 High Speed Civil Transport with a design range of 6500 n.mi. The design mission assumed an all-supersonic cruise segment and no community noise or sonic boom constraints. The study airplane was developed in order to examine the technology requirements for such a vehicle and to provide an unconstrained baseline from which to assess changes in technology levels, sonic boom limits, or community noise constraints in future studies. The propulsion, structure, and materials technologies utilized in the sizing of the study aircraft were assumed to represent a technology availability date of 2015. The study airplane was a derivative of a previously developed Mach 3 concept and utilized advanced afterburning turbojet engines and passive airframe thermal protection. Details of the configuration development, aerodynamic design, propulsion system, mass properties, and mission performance are presented. The study airplane was estimated to weigh approx. 866,000 lbs. Although an aircraft of this size is a marginally acceptable candidate to fit into the world airport infrastructure, it was concluded that the inclusion of community noise or sonic boom constraints would quickly cause the aircraft to grow beyond acceptable limits using the assumed technology levels.
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40 CFR 300.515 - Requirements for state involvement in remedial and enforcement response.
Code of Federal Regulations, 2012 CFR
2012-07-01
... not limited to, remedial investigations, feasibility studies, and remedial designs, the state agency... later than the early stages of the comparative analysis described in § 300.430(e)(9), such that... separate phase or activity, for supervising the remedial design and construction of the entire remedy. (2...
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40 CFR 300.515 - Requirements for state involvement in remedial and enforcement response.
Code of Federal Regulations, 2010 CFR
2010-07-01
... not limited to, remedial investigations, feasibility studies, and remedial designs, the state agency... later than the early stages of the comparative analysis described in § 300.430(e)(9), such that... separate phase or activity, for supervising the remedial design and construction of the entire remedy. (2...
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40 CFR 300.515 - Requirements for state involvement in remedial and enforcement response.
Code of Federal Regulations, 2014 CFR
2014-07-01
... not limited to, remedial investigations, feasibility studies, and remedial designs, the state agency... later than the early stages of the comparative analysis described in § 300.430(e)(9), such that... separate phase or activity, for supervising the remedial design and construction of the entire remedy. (2...
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40 CFR 300.515 - Requirements for state involvement in remedial and enforcement response.
Code of Federal Regulations, 2013 CFR
2013-07-01
... not limited to, remedial investigations, feasibility studies, and remedial designs, the state agency... later than the early stages of the comparative analysis described in § 300.430(e)(9), such that... separate phase or activity, for supervising the remedial design and construction of the entire remedy. (2...
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40 CFR 300.515 - Requirements for state involvement in remedial and enforcement response.
Code of Federal Regulations, 2011 CFR
2011-07-01
... not limited to, remedial investigations, feasibility studies, and remedial designs, the state agency... later than the early stages of the comparative analysis described in § 300.430(e)(9), such that... separate phase or activity, for supervising the remedial design and construction of the entire remedy. (2...
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ERIC Educational Resources Information Center
Phan, Huy P.; Ngu, Bing H.
2017-01-01
In social sciences, the use of stringent methodological approaches is gaining increasing emphasis. Researchers have recognized the limitations of cross-sectional, non-manipulative data in the study of causality. True experimental designs, in contrast, are preferred as they represent rigorous standards for achieving causal flows between variables.…
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Impact of Instructor Teaching Style and Content Course on Mathematics Anxiety of Preservice Teachers
ERIC Educational Resources Information Center
Van der Sandt, Suriza; O'Brien, Steve
2017-01-01
Integrative-STEM methodologies entail integrating multiple disciplines with active design-centric teaching and learning methods. If math anxiety is prevalent, for teachers or students, then both the level of integration and design thinking may be limited. This quantitative study of 160 preservice teachers investigated how math anxiety was impacted…
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Beyond Member-Checking: A Dialogic Approach to the Research Interview
ERIC Educational Resources Information Center
Harvey, Lou
2015-01-01
This article presents a dialogic qualitative interview design for a narrative study of six international UK university students' motivation for learning English. Based on the work of Mikhail Bakhtin, this design was developed in order to address the limitations of member-checking [Lincoln, Y. S., and E. G. Guba. 1985. "Naturalistic…
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Colour Size Illusion on Liquid Crystal Displays and Design Guidelines for Bioinformatics Tools
ERIC Educational Resources Information Center
Yoo, Hyun Seung; Smith-Jackson, Tonya L.
2011-01-01
Although the influence of colour on size perception has been known for a century, there is only limited research on interventions that can reduce this effect. This study was therefore undertaken in order to identify appropriate interventions and propose design guidelines for information visualisation, especially in applications where size…
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An Empirical Study of Eight Nonparametric Tests in Hierarchical Regression.
ERIC Educational Resources Information Center
Harwell, Michael; Serlin, Ronald C.
When normality does not hold, nonparametric tests represent an important data-analytic alternative to parametric tests. However, the use of nonparametric tests in educational research has been limited by the absence of easily performed tests for complex experimental designs and analyses, such as factorial designs and multiple regression analyses,…
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An Approach to Participatory Instructional Design in Secondary Education: An Exploratory Study
ERIC Educational Resources Information Center
Konings, Karen D.; Brand-Gruwel, Saskia; van Merrienboer, Jeroen J. G.
2010-01-01
Background: Teachers have limited insight in students' perspectives on education, although these perspectives influence quality of learning. As students' and teachers' perspectives differ considerably, there is a need for teachers to learn more about students' experiences and ideas about education. Participatory design might be a good strategy for…
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Sexuality Education in South African Schools: The Challenge for Civil Society Organisations
ERIC Educational Resources Information Center
Adams Tucker, Leigh; George, Gavin; Reardon, Candice; Panday, Saadhna
2017-01-01
Objective: Drawing on the perceptions of various key stakeholders, the paper explores the strengths and limitations of involving civil society organisations in the delivery of HIV and AIDS and sexuality education in South African schools. Design: Qualitative study with a cross-sectional design. Setting: Research was conducted at 16 public…
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From Airy to Abbe: quantifying the effects of wide-angle focusing for scalar spherical waves
NASA Astrophysics Data System (ADS)
Calm, Yitzi M.; Merlo, Juan M.; Burns, Michael J.; Naughton, Michael J.
2017-10-01
Recent advances in optical microscopy have enabled imaging with spatial resolution beyond the diffraction limit. This limit is sometimes taken as one of several different criteria according to different conventions, including Rayleigh’s 0.61λ /NA, Abbe’s 0.5λ /NA, and Sparrow’s 0.47λ /NA. In this paper, we perform a parametric study, numerically integrating the scalar Kirchhoff diffraction integrals, and we propose new functional forms for the resolution limits derived from scalar focusing. The new expressions remain accurate under wide angle focusing, up to 90^\\circ . Our results could materially impact the design of high intensity focused ultrasound systems, and can be used as a qualitative guideline for the design of a particular type of planar optical element: the flat lens metasurface.
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NASA Astrophysics Data System (ADS)
Lai, Bang-Cheng; He, Jian-Jun
2018-03-01
In this paper, we construct a novel 4D autonomous chaotic system with four cross-product nonlinear terms and five equilibria. The multiple coexisting attractors and the multiscroll attractor of the system are numerically investigated. Research results show that the system has various types of multiple attractors, including three strange attractors with a limit cycle, three limit cycles, two strange attractors with a pair of limit cycles, two coexisting strange attractors. By using the passive control theory, a controller is designed for controlling the chaos of the system. Both analytical and numerical studies verify that the designed controller can suppress chaotic motion and stabilise the system at the origin. Moreover, an electronic circuit is presented for implementing the chaotic system.
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Impact of care pathways for in-hospital management of COPD exacerbation: a systematic review.
Lodewijckx, C; Sermeus, W; Panella, M; Deneckere, S; Leigheb, F; Decramer, M; Vanhaecht, K
2011-11-01
In-hospital management of COPD exacerbation is suboptimal, and outcomes are poor. Care pathways are a possible strategy for optimizing care processes and outcomes. The aim of the literature review was to explore characteristics of existing care pathways for in-hospital management of COPD exacerbations and to address their impact on performance of care processes, clinical outcomes, and team functioning. A literature search was conducted for articles published between 1990 and 2010 in the electronic databases of Medline, CINAHL, EMBASE, and Cochrane Library. Main inclusion criteria were (I) patients hospitalized for a COPD exacerbation; (II) implementation and evaluation of a care pathway; (III) report of original research, including experimental and quasi experimental designs, variance analysis, and interviews of professionals and patients about their perception on pathway effectiveness. Four studies with a quasi experimental design were included. Three studies used a pre-post test design; the fourth study was a non randomized controlled trial comparing an experimental group where patients were treated according to a care pathway with a control group where usual care was provided. The four studied care pathways were multidisciplinary structured care plans, outlining time-specific clinical interventions and responsibilities by discipline. Statistic analyses were rarely performed, and the trials used very divergent indicators to evaluate the impact of the care pathways. The studies described positive effects on blood sampling, daily weight measurement, arterial blood gas measurement, referral to rehabilitation, feelings of anxiety, length of stay, readmission, and in-hospital mortality. Research on COPD care pathways is very limited. The studies described few positive effects of the care pathways on diagnostic processes and on clinical outcomes. Though due to limited statistical analysis and weak design of the studies, the internal validity of results is limited. Therefore, based on these studies the impact of care pathways on COPD exacerbation is inconclusive. These findings indicate the need for properly designed research like a cluster randomized controlled trial to evaluate the impact of COPD care pathways on performance of care processes, clinical outcomes, and teamwork. Copyright © 2011 Elsevier Ltd. All rights reserved.
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NASA Astrophysics Data System (ADS)
Robati, Masoud
This Doctorate program focuses on the evaluation and improving the rutting resistance of micro-surfacing mixtures. There are many research problems related to the rutting resistance of micro-surfacing mixtures that still require further research to be solved. The main objective of this Ph.D. program is to experimentally and analytically study and improve rutting resistance of micro-surfacing mixtures. During this Ph.D. program major aspects related to the rutting resistance of micro-surfacing mixtures are investigated and presented as follow: 1) evaluation of a modification of current micro-surfacing mix design procedures: On the basis of this effort, a new mix design procedure is proposed for type III micro-surfacing mixtures as rut-fill materials on the road surface. Unlike the current mix design guidelines and specification, the new mix design is capable of selecting the optimum mix proportions for micro-surfacing mixtures; 2) evaluation of test methods and selection of aggregate grading for type III application of micro-surfacing: Within the term of this study, a new specification for selection of aggregate grading for type III application of micro-surfacing is proposed; 3) evaluation of repeatability and reproducibility of micro-surfacing mixture design tests: In this study, limits for repeatability and reproducibility of micro-surfacing mix design tests are presented; 4) a new conceptual model for filler stiffening effect on asphalt mastic of micro-surfacing: A new model is proposed, which is able to establish limits for minimum and maximum filler concentrations in the micro-surfacing mixture base on only the filler important physical and chemical properties; 5) incorporation of reclaimed asphalt pavement and post-fabrication asphalt shingles in micro-surfacing mixture: The effectiveness of newly developed mix design procedure for micro-surfacing mixtures is further validated using recycled materials. The results present the limits for the use of RAP and RAS amount in micro-surfacing mixtures; 6) new colored micro-surfacing formulations with improved durability and performance: The significant improvement of around 45% in rutting resistance of colored and conventional micro-surfacing mixtures is achieved through employing low penetration grade bitumen polymer modified asphalt emulsion stabilized using nanoparticles.
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USDA-ARS?s Scientific Manuscript database
Objectives To determine the associations between diet quality, body mass index (BMI), and health-related quality of life (HRQOL) as assessed by the health and activity limitation index (HALex) in older adults. Design Multivariate linear regression models were used to analyze associations between Di...
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ERIC Educational Resources Information Center
McIntyre, Patrick J.
1974-01-01
Reported is a study to verify the pattern of bias associated with the Model Identification Test and to determine its source. This instrument is a limited verbal science test designed to determine the knowledge possessed by elementary school children of selected concepts related to "the particle nature of matter." (PEB)
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Yeh, Chun-Ting; Brunette, T J; Baker, David; McIntosh-Smith, Simon; Parmeggiani, Fabio
2018-02-01
Computational protein design methods have enabled the design of novel protein structures, but they are often still limited to small proteins and symmetric systems. To expand the size of designable proteins while controlling the overall structure, we developed Elfin, a genetic algorithm for the design of novel proteins with custom shapes using structural building blocks derived from experimentally verified repeat proteins. By combining building blocks with compatible interfaces, it is possible to rapidly build non-symmetric large structures (>1000 amino acids) that match three-dimensional geometric descriptions provided by the user. A run time of about 20min on a laptop computer for a 3000 amino acid structure makes Elfin accessible to users with limited computational resources. Protein structures with controlled geometry will allow the systematic study of the effect of spatial arrangement of enzymes and signaling molecules, and provide new scaffolds for functional nanomaterials. Copyright © 2017 Elsevier Inc. All rights reserved.
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Design and Analysis of Precise Pointing Systems
NASA Technical Reports Server (NTRS)
Kim, Young K.
2000-01-01
The mathematical models of Glovebox Integrated Microgravity Isolation Technology (g- LIMIT) dynamics/control system, which include six degrees of freedom (DOF) equations of motion, mathematical models of position sensors, accelerometers and actuators, and acceleration and position controller, were developed using MATLAB and TREETOPS simulations. Optimal control parameters of G-LIMIT control system were determined through sensitivity studies and its performance were evaluated with the TREETOPS model of G-LIMIT dynamics and control system. The functional operation and performance of the Tektronix DTM920 digital thermometer were studied and the inputs to the crew procedures and training of the DTM920 were documented.
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Code of Federal Regulations, 2012 CFR
2012-04-01
... Designated contract market and swap execution facility position limits and accountability rules. (a) Spot... rules and procedures for monitoring and enforcing spot-month position limits set at levels no greater... monitoring and enforcing spot-month position limits set at levels no greater than 25 percent of estimated...
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Code of Federal Regulations, 2013 CFR
2013-04-01
... Designated contract market and swap execution facility position limits and accountability rules. (a) Spot... rules and procedures for monitoring and enforcing spot-month position limits set at levels no greater... monitoring and enforcing spot-month position limits set at levels no greater than 25 percent of estimated...
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ERIC Educational Resources Information Center
Kelley, Todd R.; Sung, Euisuk
2017-01-01
The purpose of this article is to provide awareness of the danger of design fixation and promote the uses of brainstorming early in the design process--before fixation limits creative ideas. The authors challenged technology teachers to carefully limit the use of design examples too early in the process and provided suggestions for facilitating…
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48 CFR 36.609-1 - Design within funding limitations.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Design within funding... Services 36.609-1 Design within funding limitations. (a) The Government may require the architect-engineer contractor to design the project so that construction costs will not exceed a contractually specified dollar...
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ASSESSING WATERBORNE RISKS: AN INTRODUCTION
Information in this article can help readers evaluate the results of epidemiologic studies of
waterborne disease risks. It is important that readers understand the various epidemiologic study
designs, their strengths and limitations, and potential biases. Terminolog... -
Brownell, Sara E.; Kloser, Matthew J.; Fukami, Tadashi; Shavelson, Richard J.
2013-01-01
The shift from cookbook to authentic research-based lab courses in undergraduate biology necessitates the need for evaluation and assessment of these novel courses. Although the biology education community has made progress in this area, it is important that we interpret the effectiveness of these courses with caution and remain mindful of inherent limitations to our study designs that may impact internal and external validity. The specific context of a research study can have a dramatic impact on the conclusions. We present a case study of our own three-year investigation of the impact of a research-based introductory lab course, highlighting how volunteer students, a lack of a comparison group, and small sample sizes can be limitations of a study design that can affect the interpretation of the effectiveness of a course. PMID:24358380
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Brownell, Sara E; Kloser, Matthew J; Fukami, Tadashi; Shavelson, Richard J
2013-01-01
The shift from cookbook to authentic research-based lab courses in undergraduate biology necessitates the need for evaluation and assessment of these novel courses. Although the biology education community has made progress in this area, it is important that we interpret the effectiveness of these courses with caution and remain mindful of inherent limitations to our study designs that may impact internal and external validity. The specific context of a research study can have a dramatic impact on the conclusions. We present a case study of our own three-year investigation of the impact of a research-based introductory lab course, highlighting how volunteer students, a lack of a comparison group, and small sample sizes can be limitations of a study design that can affect the interpretation of the effectiveness of a course.
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Goodman, Michael; Dana Flanders, W
2007-04-01
We compare methodological approaches for evaluating gene-environment interaction using a planned study of pediatric leukemia as a practical example. We considered three design options: a full case-control study (Option I), a case-only study (Option II), and a partial case-control study (Option III), in which information on controls is limited to environmental exposure only. For each design option we determined its ability to measure the main effects of environmental factor E and genetic factor G, and the interaction between E and G. Using the leukemia study example, we calculated sample sizes required to detect and odds ratio (OR) of 2.0 for E alone, an OR of 10 for G alone and an interaction G x E of 3. Option I allows measuring both main effects and interaction, but requires a total sample size of 1,500 cases and 1,500 controls. Option II allows measuring only interaction, but requires just 121 cases. Option III allows calculating the main effect of E, and interaction, but not the main effect of G, and requires a total of 156 cases and 133 controls. In this case, the partial case-control study (Option III) appears to be more efficient with respect to its ability to answer the research questions for the amount of resources required. The design options considered in this example are not limited to observational epidemiology and may be applicable in studies of pharmacogenomics, survivorship, and other areas of pediatric ALL research.
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Controlling hazardous reactions during voltage reversal of high energy lithium cells
NASA Technical Reports Server (NTRS)
Domeniconi, M.
1983-01-01
The roll of general cell design characteristics in preventing hazardous reactions during voltage reversal of lithium cells is discussed. Anode limited versus cathode limited design and case positive versus case negative design are addressed.
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Silicon ribbon study program. [dendritic crystals for use in solar cells
NASA Technical Reports Server (NTRS)
Seidensticker, R. G.; Duncan, C. S.
1975-01-01
The feasibility is studied of growing wide, thin silicon dendritic web for solar cell fabrication and conceptual designs are developed for the apparatus required. An analysis of the mechanisms of dendritic web growth indicated that there were no apparent fundamental limitations to the process. The analysis yielded quantitative guidelines for the thermal conditions required for this mode of crystal growth. Crucible designs were then investigated: the usual quartz crucible configurations and configurations in which silicon itself is used for the crucible. The quartz crucible design is feasible and is incorporated into a conceptual design for a laboratory scale crystal growth facility capable of semi-automated quasi-continuous operation.
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Microstructural evaluation of cumulative fatigue damage in a plant component sample
DOE Office of Scientific and Technical Information (OSTI.GOV)
Fukuoka, C.; Nakagawa, Y.G.; Yoshida, K.
1996-12-31
Fatigue damage accumulated in a real plant was evaluated in terms of microstructural conditioning. Microstructural damage induced in laboratory by cyclic deformation near and below the fatigue limit was also examined. A Transmission Electron Microscopy (TEM) technique called the Selected Area Diffraction (SAD) method was employed in this study. In earlier studies, it was found that the SAD value indicating a magnitude of crystallographic misorientation in the substructure (dislocation cells) was increasing with the increase of fatigue damage accumulation. Small samples removed from PWR feed water nozzle welds were examined by the SAD. It was found that the damage statemore » measured by the SAD well agreed with the morphological evidence. Cyclic stresses near or below the fatigue limit were applied to samples taken from a SA508 steel plate at various stresses. The SAD value increased even below the fatigue limit, but there was no sign of microstructural conditioning below the stresses of 50% of the fatigue limit. These results suggested that at stresses below the current design curve (below half the fatigue limit) no microstructural conditioning proceeded. It was concluded that the microstructural method was effective to evaluate damage accumulation in real plant components, and also that the current design curve was adequate in terms of microstructural conditioning state.« less
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Optimization of Root Section for Ultra-long Steam Turbine Rotor Blade
NASA Astrophysics Data System (ADS)
Hála, Jindřich; Luxa, Martin; Šimurda, David; Bobčík, Marek; Novák, Ondřej; Rudas, Bartoloměj; Synáč, Jaroslav
2018-04-01
This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Mach number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements (optical and pneumatic).
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Robust EM Continual Reassessment Method in Oncology Dose Finding
Yuan, Ying; Yin, Guosheng
2012-01-01
The continual reassessment method (CRM) is a commonly used dose-finding design for phase I clinical trials. Practical applications of this method have been restricted by two limitations: (1) the requirement that the toxicity outcome needs to be observed shortly after the initiation of the treatment; and (2) the potential sensitivity to the prespecified toxicity probability at each dose. To overcome these limitations, we naturally treat the unobserved toxicity outcomes as missing data, and use the expectation-maximization (EM) algorithm to estimate the dose toxicity probabilities based on the incomplete data to direct dose assignment. To enhance the robustness of the design, we propose prespecifying multiple sets of toxicity probabilities, each set corresponding to an individual CRM model. We carry out these multiple CRMs in parallel, across which model selection and model averaging procedures are used to make more robust inference. We evaluate the operating characteristics of the proposed robust EM-CRM designs through simulation studies and show that the proposed methods satisfactorily resolve both limitations of the CRM. Besides improving the MTD selection percentage, the new designs dramatically shorten the duration of the trial, and are robust to the prespecification of the toxicity probabilities. PMID:22375092
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Aboalnaja, Khaled Omer; Yaghmoor, Soonham; Kumosani, Taha Abdullah; McClements, David Julian
2016-09-01
The efficacy of many hydrophobic bioactives (pharmaceuticals, supplements, and nutraceuticals) is limited due to their relatively low or highly variable bioavailability. Nanoemulsions consisting of small lipid droplets (r < 100 nm) dispersed in water can be designed to improve bioavailability. The major factors limiting the oral bioavailability of hydrophobic bioactive agents are highlighted: bioaccessibility, absorption and transformation. Two nanoemulsion-based approaches to control these processes and improve bioavailability are discussed: nanoemulsion delivery systems (NDS) and nanoemulsion excipient systems (NES). In NDS, hydrophobic bioactives are dissolved within the lipid phase of oil-in-water nanoemulsions. In NES, the bioactives are present within a conventional drug, supplement, or food, which is consumed with an oil-in-water nanoemulsion. Examples of NDS and NES utilization to improve bioactive bioavailability are given. Considerable progress has been made in nanoemulsion design, fabrication, and testing. This knowledge facilitates the design of new formulations to improve the bioavailability of pharmaceuticals, supplements, and nutraceuticals. NDS and NES must be carefully designed based on the major factors limiting the bioavailability of specific bioactives. Research is still required to ensure these systems are commercially viable, and to demonstrate their safety and efficacy using animal and human feeding studies.
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Designing a biomechanics investigation: choosing the right model.
Olson, Steven A; Marsh, J Lawrence; Anderson, Donald D; Latta Pe, Loren L
2012-12-01
Physical testing is commonly performed to answer important biomechanical questions in the treatment of patients with fractures and other orthopaedic conditions. However, a variety of mistakes that are made in performing such investigations can severely limit their impact. The goal of this article is to discuss important aspects of study design to consider when planning for biomechanical investigations so that the studies can provide maximal benefit to the field. The best mechanical investigations begin with a good research question, one that comes out of patient care experience, is clearly defined, and can be stated concisely. The first practical issue to be considered is often choosing the type of physical specimens to be tested to address the research question. A related issue involves determining how many specimens will be needed to answer the posed mechanical question. Cadavers are generally still the closest to the actual clinical situation, but they are limited by interspecimen variability, which often requires a matched pair design that can address only one question. Simulated bone specimens limit variability and can replicate normal and osteoporotic bone. In planning the physical testing, the critical mechanical variables involved in answering the research question must be identified and due consideration given to deciding how best to measure them. Another important issue that arises relates to whether or not single static loadings will suffice in the testing (eg, to study construct stiffness) or whether cyclic dynamic testing is necessary (eg, to study late failure likely attributable to fatigue). To summarize, experimental design should be carefully planned before initiating mechanical testing. Sample size calculations should be performed to ensure adequate power and that clinically relevant differences can be detected. This pregame analysis can save significant time and cost and greatly increase the likelihood that the results will advance knowledge.
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Design considerations for near-infrared filter photometry: effects of noise sources and selectivity.
Tarumi, Toshiyasu; Amerov, Airat K; Arnold, Mark A; Small, Gary W
2009-06-01
Optimal filter design of two-channel near-infrared filter photometers is investigated for simulated two-component systems consisting of an analyte and a spectrally overlapping interferent. The degree of overlap between the analyte and interferent bands is varied over three levels. The optimal design is obtained for three cases: a source or background flicker noise limited case, a shot noise limited case, and a detector noise limited case. Conventional photometers consist of narrow-band optical filters with their bands located at discrete wavelengths. However, the use of broadband optical filters with overlapping responses has been proposed to obtain as much signal as possible from a weak and broad analyte band typical of near-infrared absorptions. One question regarding the use of broadband optical filters with overlapping responses is the selectivity achieved by such filters. The selectivity of two-channel photometers is evaluated on the basis of the angle between the analyte and interferent vectors in the space spanned by the relative change recorded for each of the two detector channels. This study shows that for the shot noise limited or detector noise limited cases, the slight decrease in selectivity with the use of broadband optical filters can be compensated by the higher signal-to-noise ratio afforded by the use of such filters. For the source noise limited case, the best quantitative results are obtained with the use of narrow-band non-overlapping optical filters.
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Strategic Design and Fabrication of Engineered Scaffolds for Articular Cartilage Repair
Izadifar, Zohreh; Chen, Xiongbiao; Kulyk, William
2012-01-01
Damage to articular cartilage can eventually lead to osteoarthritis (OA), a debilitating, degenerative joint disease that affects millions of people around the world. The limited natural healing ability of cartilage and the limitations of currently available therapies make treatment of cartilage defects a challenging clinical issue. Hopes have been raised for the repair of articular cartilage with the help of supportive structures, called scaffolds, created through tissue engineering (TE). Over the past two decades, different designs and fabrication techniques have been investigated for developing TE scaffolds suitable for the construction of transplantable artificial cartilage tissue substitutes. Advances in fabrication technologies now enable the strategic design of scaffolds with complex, biomimetic structures and properties. In particular, scaffolds with hybrid and/or biomimetic zonal designs have recently been developed for cartilage tissue engineering applications. This paper reviews critical aspects of the design of engineered scaffolds for articular cartilage repair as well as the available advanced fabrication techniques. In addition, recent studies on the design of hybrid and zonal scaffolds for use in cartilage tissue repair are highlighted. PMID:24955748
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A study on the optimum fast neutron flux for boron neutron capture therapy of deep-seated tumors.
Rasouli, Fatemeh S; Masoudi, S Farhad
2015-02-01
High-energy neutrons, named fast neutrons which have a number of undesirable biological effects on tissue, are a challenging problem in beam designing for Boron Neutron Capture Therapy, BNCT. In spite of this fact, there is not a widely accepted criterion to guide the beam designer to determine the appropriate contribution of fast neutrons in the spectrum. Although a number of researchers have proposed a target value for the ratio of fast neutron flux to epithermal neutron flux, it can be shown that this criterion may not provide the optimum treatment condition. This simulation study deals with the determination of the optimum contribution of fast neutron flux in the beam for BNCT of deep-seated tumors. Since the dose due to these high-energy neutrons damages shallow tissues, delivered dose to skin is considered as a measure for determining the acceptability of the designed beam. To serve this purpose, various beam shaping assemblies that result in different contribution of fast neutron flux are designed. The performances of the neutron beams corresponding to such configurations are assessed in a simulated head phantom. It is shown that the previously used criterion, which suggests a limit value for the contribution of fast neutrons in beam, does not necessarily provide the optimum condition. Accordingly, it is important to specify other complementary limits considering the energy of fast neutrons. By analyzing various neutron spectra, two limits on fast neutron flux are proposed and their validity is investigated. The results show that considering these limits together with the widely accepted IAEA criteria makes it possible to have a more realistic assessment of sufficiency of the designed beam. Satisfying these criteria not only leads to reduction of delivered dose to skin, but also increases the advantage depth in tissue and delivered dose to tumor during the treatment time. The Monte Carlo Code, MCNP-X, is used to perform these simulations. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Laursen, Esben Skov; Møller, Louise
2015-01-01
This paper describes a case study comparing the understanding of design intent between industrial designers and design engineers. The study is based on the hypothesis that it is not all aspects of the design intent that are equally difficult to share between industrial designers and design engineers in the product development process. The study builds on five semi-structured interviews, where two industrial designers and three design engineers were interviewed about different aspects of the design intent. Based on our results, there seem to be indications that the more complex and abstract elements of industrial design knowledge such as the meaning, semantics, values, emotions and social aspects of the product are less shared by the design engineers. Moreover, the results also indicate that the different aspects of the design intent are perceived separately, rather than as part of a whole by the design engineers. The connection between the different aspects of the design intent is not shared between the industrial designer and design engineer making the shared knowledge less meaningful to the design engineers. The results of this study cannot be claimed to be conclusive due to the limited empirical material. Further investigation and analytically richer data are required in order to verify and broaden the findings. More case studies have therefore been planned in order to understand the area better.
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Systematic review of stigma reducing interventions for African/Black diasporic women
Loutfy, Mona; Tharao, Wangari; Logie, Carmen; Aden, Muna A; Chambers, Lori A; Wu, Wei; Abdelmaseh, Marym; Calzavara, Liviana
2015-01-01
Introduction Literature indicates that racism, sexism, homophobia and HIV-related stigma have adverse impacts on health, well-being, and quality of life among HIV-positive women of African descent (African/Black diaspora). However, limited evidence exists on the effectiveness of interventions aimed at reducing stigma tailored for these women. This study systematically reviewed randomized controlled trials (RCTs), non-randomized observational and quasi-experimental studies evaluating the effectiveness of interventions aimed at reducing stigma experienced by this population. Methods The Cochrane methodology was used to develop a search strategy in consultation with a librarian scientist. Databases searched included the Cochrane Library, Ovid EMBASE, PsycInfo, and 10 others. Two reviewers independently assessed the studies for potential relevance and conducted the Cochrane grading of RCTs to assess risk of bias and the Newcastle–Ottawa scale to assess the quality of non-randomized studies. Eligible papers were selected if they employed an intervention design with African/Black diasporic women living with HIV as the target population and had a primary outcome of stigma reduction. Results Of the five studies that met all of the eligibility criteria, four demonstrated the effectiveness of interventions in reducing HIV-related stigma. Only two of the five studies were designed specifically for HIV-positive African/Black diasporic women. Limitations included the absence of interventions addressing other forms of stigma and discrimination (e.g. gender discrimination, racism, heterosexism). Conclusions Our findings suggest that there are limited interventions designed to address multiple forms of stigma, including gender and racial discrimination, experienced by HIV-positive African/Black diasporic women. PMID:25862565
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Systematic review of stigma reducing interventions for African/Black diasporic women.
Loutfy, Mona; Tharao, Wangari; Logie, Carmen; Aden, Muna A; Chambers, Lori A; Wu, Wei; Abdelmaseh, Marym; Calzavara, Liviana
2015-01-01
Literature indicates that racism, sexism, homophobia and HIV-related stigma have adverse impacts on health, well-being, and quality of life among HIV-positive women of African descent (African/Black diaspora). However, limited evidence exists on the effectiveness of interventions aimed at reducing stigma tailored for these women. This study systematically reviewed randomized controlled trials (RCTs), non-randomized observational and quasi-experimental studies evaluating the effectiveness of interventions aimed at reducing stigma experienced by this population. The Cochrane methodology was used to develop a search strategy in consultation with a librarian scientist. Databases searched included the Cochrane Library, Ovid EMBASE, PsycInfo, and 10 others. Two reviewers independently assessed the studies for potential relevance and conducted the Cochrane grading of RCTs to assess risk of bias and the Newcastle-Ottawa scale to assess the quality of non-randomized studies. Eligible papers were selected if they employed an intervention design with African/Black diasporic women living with HIV as the target population and had a primary outcome of stigma reduction. Of the five studies that met all of the eligibility criteria, four demonstrated the effectiveness of interventions in reducing HIV-related stigma. Only two of the five studies were designed specifically for HIV-positive African/Black diasporic women. Limitations included the absence of interventions addressing other forms of stigma and discrimination (e.g. gender discrimination, racism, heterosexism). Our findings suggest that there are limited interventions designed to address multiple forms of stigma, including gender and racial discrimination, experienced by HIV-positive African/Black diasporic women.
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Mindfulness-based interventions with youth: A comprehensive meta-analysis of group-design studies.
Klingbeil, David A; Renshaw, Tyler L; Willenbrink, Jessica B; Copek, Rebecca A; Chan, Kai Tai; Haddock, Aaron; Yassine, Jordan; Clifton, Jesse
2017-08-01
The treatment effects of Mindfulness-Based Interventions (MBIs) with youth were synthesized from 76 studies involving 6121 participants. A total of 885 effect sizes were aggregated using meta-regression with robust variance estimation. Overall, MBIs were associated with small treatment effects in studies using pre-post (g=0.305, SE=0.039) and controlled designs (g=0.322, SE=0.040). Treatment effects were measured after a follow-up period in 24 studies (n=1963). Results demonstrated that treatment effects were larger at follow-up than post-treatment in pre-post (g=0.462, SE=0.118) and controlled designs (g=0.402, SE=0.081). Moderator analyses indicated that intervention setting and intervention dosage were not meaningfully related to outcomes after controlling for study design quality. With that said, the between-study heterogeneity in the intercept-only models was consistently small, thus limiting the amount of variance for the moderators to explain. A series of exploratory analyses were used to investigate the differential effectiveness of MBIs across four therapeutic process domains and seven therapeutic outcome domains. Small, positive results were generally observed across the process and outcome domains. Notably, MBIs were associated with moderate effects on the process variable of mindfulness in controlled studies (n=1108, g=0.510). Limitations and directions for future research and practice are discussed. Copyright © 2017 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.
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Waste Handeling Building Conceptual Study
DOE Office of Scientific and Technical Information (OSTI.GOV)
G.W. Rowe
2000-11-06
The objective of the ''Waste Handling Building Conceptual Study'' is to develop proposed design requirements for the repository Waste Handling System in sufficient detail to allow the surface facility design to proceed to the License Application effort if the proposed requirements are approved by DOE. Proposed requirements were developed to further refine waste handling facility performance characteristics and design constraints with an emphasis on supporting modular construction, minimizing fuel inventory, and optimizing facility maintainability and dry handling operations. To meet this objective, this study attempts to provide an alternative design to the Site Recommendation design that is flexible, simple, reliable,more » and can be constructed in phases. The design concept will be input to the ''Modular Design/Construction and Operation Options Report'', which will address the overall program objectives and direction, including options and issues associated with transportation, the subsurface facility, and Total System Life Cycle Cost. This study (herein) is limited to the Waste Handling System and associated fuel staging system.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Goulart, Bernardo H.L., E-mail: bhg@uw.edu; University of Washington, Seattle, Washington; Ramsey, Scott D.
Comparative effectiveness research (CER) has emerged as an approach to improve quality of care and patient outcomes while reducing healthcare costs by providing evidence to guide healthcare decisions. Randomized controlled trials (RCTs) have represented the ideal study design to support treatment decisions in head-and-neck (H and N) cancers. In RCTs, formal chance (randomization) determines treatment allocation, which prevents selection bias from distorting the measure of treatment effects. Despite this advantage, only a minority of patients qualify for inclusion in H and N RCTs, which limits the validity of their results to the broader H and N cancer patient population seenmore » in clinical practice. Randomized controlled trials often do not address other knowledge gaps in the management of H and N cancer, including treatment comparisons for rare types of H and N cancers, monitoring of rare or late toxicity events (eg, osteoradionecrosis), or in some instances an RCT is simply not feasible. Observational studies, or studies in which treatment allocation occurs independently of investigators' choice or randomization, may address several of these gaps in knowledge, thereby complementing the role of RCTs. This critical review discusses how observational CER studies complement RCTs in generating the evidence to inform healthcare decisions and improve the quality of care and outcomes of H and N cancer patients. Review topics include a balanced discussion about the strengths and limitations of both RCT and observational CER study designs; a brief description of design and analytic techniques to handle selection bias in observational studies; examples of observational studies that inform current clinical practices and management of H and N cancers; and suggestions for relevant CER questions that could be addressed by an observational study design.« less
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Goulart, Bernardo H L; Ramsey, Scott D; Parvathaneni, Upendra
2014-01-01
Comparative effectiveness research (CER) has emerged as an approach to improve quality of care and patient outcomes while reducing healthcare costs by providing evidence to guide healthcare decisions. Randomized controlled trials (RCTs) have represented the ideal study design to support treatment decisions in head-and-neck (H&N) cancers. In RCTs, formal chance (randomization) determines treatment allocation, which prevents selection bias from distorting the measure of treatment effects. Despite this advantage, only a minority of patients qualify for inclusion in H&N RCTs, which limits the validity of their results to the broader H&N cancer patient population seen in clinical practice. Randomized controlled trials often do not address other knowledge gaps in the management of H&N cancer, including treatment comparisons for rare types of H&N cancers, monitoring of rare or late toxicity events (eg, osteoradionecrosis), or in some instances an RCT is simply not feasible. Observational studies, or studies in which treatment allocation occurs independently of investigators' choice or randomization, may address several of these gaps in knowledge, thereby complementing the role of RCTs. This critical review discusses how observational CER studies complement RCTs in generating the evidence to inform healthcare decisions and improve the quality of care and outcomes of H&N cancer patients. Review topics include a balanced discussion about the strengths and limitations of both RCT and observational CER study designs; a brief description of design and analytic techniques to handle selection bias in observational studies; examples of observational studies that inform current clinical practices and management of H&N cancers; and suggestions for relevant CER questions that could be addressed by an observational study design. Copyright © 2014 Elsevier Inc. All rights reserved.
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Comparison of study designs for acute otitis media trials.
Pichichero, Michael E; Casey, Janet R
2008-06-01
A framework for evaluating the efficacy of antibiotics in development as well as those currently approved for acute otitis media (AOM) is needed. Review strengths and limitations of various antibiotic trial designs and their outcome measures. A review of 157 published trials involving 36,710 subjects for the treatment of AOM. AOM trials have three designs: (1) clinical, clinical diagnosis and assessment of outcomes; (2) single tympanocentesis, microbiologic diagnosis (by middle ear fluid culture) and clinical assessment of outcomes; and (3) double tympanocentesis, microbiologic diagnosis and microbiologic outcome assessment. Identifiable strengths and limitations of each design are reviewed. Case definitions for entry of children in trials of AOM vary widely. The lack of stringent diagnostic criteria in a clinical design allows for inclusion of a significant proportion of children with a non-bacterial etiology (i.e., viral AOM or otitis media with effusion). Tympanocentesis increases diagnostic accuracy at study entry; however, the procedure is confounding because of its potentially therapeutic benefit and the procedure is not performed in a uniform manner. A second tympanocentesis allows a high sensitivity to detect microbiologic eradication, but it does not correlate with clinical outcomes in half of the cases. The timing of outcome assessment also varies widely among trials. Improved clinical diagnosis criteria for AOM are needed to enhance specificity; emphasis on a bulging tympanic membrane has the best evidence base. Tympanocentesis within study designs has merits. At study entry it assures diagnostic accuracy but may alter outcomes and it is useful to document microbiologic outcomes but lacks specificity for clinical outcomes. For all designs, test of cure assessment 2-7 days after completion of therapy seems most appropriate.
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Physics issues in diffraction limited storage ring design
NASA Astrophysics Data System (ADS)
Fan, Wei; Bai, ZhengHe; Gao, WeiWei; Feng, GuangYao; Li, WeiMin; Wang, Lin; He, DuoHui
2012-05-01
Diffraction limited electron storage ring is considered a promising candidate for future light sources, whose main characteristics are higher brilliance, better transverse coherence and better stability. The challenge of diffraction limited storage ring design is how to achieve the ultra low beam emittance with acceptable nonlinear performance. Effective linear and nonlinear parameter optimization methods based on Artificial Intelligence were developed for the storage ring physical design. As an example of application, partial physical design of HALS (Hefei Advanced Light Source), which is a diffraction limited VUV and soft X-ray light source, was introduced. Severe emittance growth due to the Intra Beam Scattering effect, which is the main obstacle to achieve ultra low emittance, was estimated quantitatively and possible cures were discussed. It is inspiring that better performance of diffraction limited storage ring can be achieved in principle with careful parameter optimization.
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FLUORESCENT TRACER EVALUATION OF PROTECTIVE CLOTHING PERFORMANCE
Field studies evaluating chemical protective clothing (CPC), which is often employed as a primary control option to reduce occupational exposures during pesticide applications, are limited. This study, supported by the U.S. Environmental Protection Agency (EPA), was designed to...
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[The case-case-time-control study design].
Wang, Jing; Zhuo, Lin; Zhan, Siyan
2014-12-01
Although the 'self-matched case-only studies' (such as the case-cross-over or self-controlled case-series method) can control the time-invariant confounders (measured or unmeasured) through design of the study, however, they can not control those confounders that vary with time. A bidirectional case-crossover design can be used to adjust the exposure-time trends. In the areas of pharmaco-epidemiology, illness often influence the future use of medications, making a bidirectional study design problematic. Suissa's case-time-control design combines the case-crossover and the case-control design which could adjust for exposure-trend bias, but the control group may reintroduce selection bias, if the matching does not go well. We propose a "case-case-time-control" design which is an extension of the case-time-control design. However, rather than using a sample of external controls, we choose those future cases as controls for current cases to counter the bias that arising from temporal trends caused by exposure to the target of interest. In the end of this article we will discuss the strength and limitations of this design based on an applied example.
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Zarit, Steven H.; Liu, Yin; Bangerter, Lauren R.; Rovine, Michael J.
2017-01-01
Objectives There is growing emphasis on empirical validation of the efficacy of community-based services for older people and their families, but research on services such as respite care faces methodological challenges that have limited the growth of outcome studies. We identify problems associated with the usual research approaches for studying respite care, with the goal of stimulating use of novel and more appropriate research designs that can lead to improved studies of community-based services. Method Using the concept of research validity, we evaluate the methodological approaches in the current literature on respite services, including adult day services, in-home respite and overnight respite. Results Although randomized control trials (RCTs) are possible in community settings, validity is compromised by practical limitations of randomization and other problems. Quasi-experimental and interrupted time series designs offer comparable validity to RCTs and can be implemented effectively in community settings. Conclusion An emphasis on RCTs by funders and researchers is not supported by scientific evidence. Alternative designs can lead to development of a valid body of research on community services such as respite. PMID:26729467
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Zarit, Steven H; Bangerter, Lauren R; Liu, Yin; Rovine, Michael J
2017-03-01
There is growing emphasis on empirical validation of the efficacy of community-based services for older people and their families, but research on services such as respite care faces methodological challenges that have limited the growth of outcome studies. We identify problems associated with the usual research approaches for studying respite care, with the goal of stimulating use of novel and more appropriate research designs that can lead to improved studies of community-based services. Using the concept of research validity, we evaluate the methodological approaches in the current literature on respite services, including adult day services, in-home respite and overnight respite. Although randomized control trials (RCTs) are possible in community settings, validity is compromised by practical limitations of randomization and other problems. Quasi-experimental and interrupted time series designs offer comparable validity to RCTs and can be implemented effectively in community settings. An emphasis on RCTs by funders and researchers is not supported by scientific evidence. Alternative designs can lead to development of a valid body of research on community services such as respite.
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The Pitfalls of Mobile Devices in Learning: A Different View and Implications for Pedagogical Design
ERIC Educational Resources Information Center
Ting, Yu-Liang
2012-01-01
Studies have been devoted to the design, implementation, and evaluation of mobile learning in practice. A common issue among students' responses toward this type of learning concerns the pitfalls of mobile devices, including small screen, limited input options, and low computational power. As a result, mobile devices are not always perceived by…
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The Lifestyle Behaviours and Exercise Beliefs of Undergraduate Student Nurses: A Descriptive Study
ERIC Educational Resources Information Center
Burke, Eimear; McCarthy, Bernard
2011-01-01
Purpose: Only limited published research is available exploring the lifestyle practices of student nurses. The purpose of this paper is to explore the lifestyle behaviours and exercise beliefs of Irish student nurses. Design/methodology/approach: A descriptive survey design was used. First-year and third-year undergraduate student nurses (n=182)…
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Structural Limitations of Model Reference Adaptive Controllers
1989-04-01
Global Uncertainty CkpVps)I4(s) kWVh(s) In [3) a design rule similar the one studied heme Dps(ms+Cs)V~)Ds = s (4) (ectly the samne when n-m--l) was...Ir represent the under the uncertainty indicated by ES and Eu. output of this structured singular value analysis, p: is an Defint 6: The Design
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ERIC Educational Resources Information Center
Crawford, April D.; Zucker, Tricia A.; Williams, Jeffrey M.; Bhavsar, Vibhuti; Landry, Susan H.
2013-01-01
Although coaching is a popular approach for enhancing the quality of Tier 1 instruction, limited research has addressed observational measures specifically designed to focus coaching on evidence-based practices. This study explains the development of the prekindergarten (pre-k) Classroom Observation Tool (COT) designed for use in a data-based…
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Design requirements for operational earth resources ground data processing
NASA Technical Reports Server (NTRS)
Baldwin, C. J.; Bradford, L. H.; Burnett, E. S.; Hutson, D. E.; Kinsler, B. A.; Kugle, D. R.; Webber, D. S.
1972-01-01
Realistic tradeoff data and evaluation techniques were studied that permit conceptual design of operational earth resources ground processing systems. Methodology for determining user requirements that utilize the limited information available from users is presented along with definitions of sensor capabilities projected into the shuttle/station era. A tentative method is presented for synthesizing candidate ground processing concepts.
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ERIC Educational Resources Information Center
Ghisletta, Paolo; Lindenberger, Ulman
2005-01-01
Cross-sectional and longitudinal analyses of age-heterogeneous samples have revealed correlational links between and within intellectual, sensory, and sensorimotor domains. Due to basic limitations of cross-sectional designs and a reluctance to disentangle antecedent-consequent relations in longitudinal designs, the functional significance and…
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Reusable Reentry Satellite (RRS): Thermal control trade study
NASA Technical Reports Server (NTRS)
Wallace, Clark
1990-01-01
The design and assessment work performed in defining the on-orbit Thermal Control Subsystem (TCS) requirements for the Reusable Reentry Satellite (RRS) is discussed. Specifically, it describes the hardware and design measures necessary for maintaining the Payload Module (PM) Environmental Control Life Support System (ECLSS) heat exchanger, the hydrazine propellant, and PM water supply within their required temperature limits.
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Make-Her-Spaces as Hybrid Places: Designing and Resisting Self Constructions in Urban Classrooms
ERIC Educational Resources Information Center
Norris, Aaminah
2014-01-01
This qualitative study analyzes how an urban schoolteacher guided her 19 tenth grade Latina and African American young women in developing positive self-concepts as expressed through the implementation of design thinking processes. This work examines how young women who had limited access to digital media negotiated their identities as they…
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Multiple Measures of Juvenile Drug Court Effectiveness: Results of a Quasi-Experimental Design
ERIC Educational Resources Information Center
Rodriguez, Nancy; Webb, Vincent J.
2004-01-01
Prior studies of juvenile drug courts have been constrained by small samples, inadequate comparison groups, or limited outcome measures. The authors report on a 3-year evaluation that examines the impact of juvenile drug court participation on recidivism and drug use. A quasi-experimental design is used to compare juveniles assigned to drug court…
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Effects of work hour reduction on residents' lives: a systematic review.
Fletcher, Kathlyn E; Underwood, Willie; Davis, Steven Q; Mangrulkar, Rajesh S; McMahon, Laurence F; Saint, Sanjay
2005-09-07
The Accreditation Council for Graduate Medical Education implemented mandatory work hour limitations in July 2003, partly out of concern for residents' well-being in the setting of sleep deprivation. These limitations are likely to also have an impact on other aspects of the lives of residents. To summarize the literature regarding the effect of interventions to reduce resident work hours on residents' education and quality of life. We searched the English-language literature about resident work hours from 1966 through April 2005 using MEDLINE, EMBASE, and Current Contents, supplemented with hand-search of additional journals, reference list review, and review of abstracts from national meetings. Studies were included that assessed a system change designed to counteract the effects of resident work hours, fatigue, or sleep deprivation; included an outcome directly related to residents; and were conducted in the United States. For each included study, 2 investigators independently abstracted data related to study quality, subjects, interventions, and findings using a standard data abstraction form. Fifty-four articles met inclusion criteria. The interventions used to decrease resident work hours varied but included night and day float teams, extra cross-coverage, and physician extenders. Outcomes included measures of resident education (operative experience, test scores, satisfaction) and quality of residents' lives (amount of sleep, well-being). Interventions to reduce resident work hours resulted in mixed effects on both operative experience and on perceived educational quality but generally improved residents' quality of life. Many studies had major limitations in their design or conduct. Past interventions suggest that residents' quality of life may improve with work hour limitations, but interpretation of the outcomes of these studies is hampered by suboptimal study design and the use of nonvalidated instruments. The long-term impact of reducing resident work hours on education remains unknown. Current and future interventions should be evaluated with more rigorous methods and should investigate links between residents' quality of life and quality of patient care.
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Eon-duval, Alex; Valax, Pascal; Solacroup, Thomas; Broly, Hervé; Gleixner, Ralf; Strat, Claire L E; Sutter, James
2012-10-01
The article describes how Quality by Design principles can be applied to the drug substance manufacturing process of an Fc fusion protein. First, the quality attributes of the product were evaluated for their potential impact on safety and efficacy using risk management tools. Similarly, process parameters that have a potential impact on critical quality attributes (CQAs) were also identified through a risk assessment. Critical process parameters were then evaluated for their impact on CQAs, individually and in interaction with each other, using multivariate design of experiment techniques during the process characterisation phase. The global multi-step Design Space, defining operational limits for the entire drug substance manufacturing process so as to ensure that the drug substance quality targets are met, was devised using predictive statistical models developed during the characterisation study. The validity of the global multi-step Design Space was then confirmed by performing the entire process, from cell bank thawing to final drug substance, at its limits during the robustness study: the quality of the final drug substance produced under different conditions was verified against predefined targets. An adaptive strategy was devised whereby the Design Space can be adjusted to the quality of the input material to ensure reliable drug substance quality. Finally, all the data obtained during the process described above, together with data generated during additional validation studies as well as manufacturing data, were used to define the control strategy for the drug substance manufacturing process using a risk assessment methodology. Copyright © 2012 Wiley-Liss, Inc.
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Experimental Design: Review and Comment.
1984-02-01
increasing the chance of finding an optimal exact design. The space- saving methods make it possible to study larger problems. Galil and Kiefer also...building along this line is limited; see, for example, Box and Hunter (1962), Hunter and Mezaki (1964), Draper and Herzberg (1971), and Box and Draper (1982...criterion a requirement that p/n not be too large. Draper and Herzberg (1979) extended the work of Box and Draper (1975) by studying the effect of
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Advanced EVA system design requirements study
NASA Technical Reports Server (NTRS)
Woods, T. G.
1988-01-01
The results are presented of a study to identify specific criteria regarding space station extravehicular activity system (EVAS) hardware requirements. Key EVA design issues include maintainability, technology readiness, LSS volume vs. EVA time available, suit pressure/cabin pressure relationship and productivity effects, crew autonomy, integration of EVA as a program resource, and standardization of task interfaces. A variety of DOD EVA systems issues were taken into consideration. Recommendations include: (1) crew limitations, not hardware limitations; (2) capability to perform all of 15 generic missions; (3) 90 days on-orbit maintainability with 50 percent duty cycle as minimum; and (4) use by payload sponsors of JSC document 10615A plus a Generic Tool Kit and Specialized Tool Kit description. EVA baseline design requirements and criteria, including requirements of various subsystems, are outlined. Space station/EVA system interface requirements and EVA accommodations are discussed in the areas of atmosphere composition and pressure, communications, data management, logistics, safe haven, SS exterior and interior requirements, and SS airlock.
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Geothermal-retrofit study for the National Orange Show Facilities in San Bernardino, California
DOE Office of Scientific and Technical Information (OSTI.GOV)
Not Available
1981-11-17
The cost and feasibility of retrofitting the National Orange Show Facilities to use geothermal heat instead of natural gas for heating are determined. Because of the limited usage of the smaller facilities the study was limited to the conversion of the six major buildings: Domed, Hobby, Citrus, Auditorium, Restaurant and Commercial. A major problem is that most of the buildings are used on a very limited basis. This drastically reduced the amount of savings that could be used to amortize the retrofit cost. Another problem is that the buildings are spread over a large area and so the below grademore » piping costs were high. Finally, all of the buildings except for the Auditorium have direct gas fired heaters that would require all new terminal heating systems. In order to limit the retrofit cost, the retrofit system was designed to handle less than the peak load. This seemed appropriate because the facility might not even be in operation when a peak load condition occurred. Also, the existing systems could be used to supplement the geothermal system if necessary. The calculated and design peak loads are summarized.« less
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Music and the brain - design of an MEG compatible piano.
Chacon-Castano, Julian; Rathbone, Daniel R; Hoffman, Rachel; Heng Yang; Pantazis, Dimitrios; Yang, Jason; Hornberger, Erik; Hanumara, Nevan C
2017-07-01
Magnetoencephalography (MEG) neuroimaging has been used to study subjects' responses when listening to music, but research into the effects of playing music has been limited by the lack of MEG compatible instruments that can operate in a magnetically shielded environment without creating electromagnetic interference. This paper describes the design and preliminary testing of an MEG compatible piano keyboard with 25 full size keys that employs a novel 3-state optical encoder design and electronics to provide realistic velocity-controlled volume modulation. This instrument will allow researchers to study musical performance on a finer timescale than fMRI and enable a range of MEG studies.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kashikhin, V. V.; Novitski, I.; Zlobin, A. V.
2017-05-01
High filed accelerator magnets with operating fields of 15-16 T based on themore » $$Nb_3Sn$$ superconductor are being considered for the LHC energy upgrade or a future Very High Energy pp Collider. Magnet design studies are being conducted in the U.S., Europe and Asia to explore the limits of the $$Nb_3Sn$$ accelerator magnet technology while optimizing the magnet design and performance parame-ters, and reducing magnet cost. The first results of these studies performed at Fermilab in the framework of the US-MDP are reported in this paper.« less
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Response of Composite Fuselage Sandwich Side Panels Subjected to Internal Pressure and Axial Tension
NASA Technical Reports Server (NTRS)
Rouse, Marshall; Ambur, Damodar R.; Dopker, Bernard; Shah, Bharat
1998-01-01
The results from an experimental and analytical study of two composite sandwich fuselage side panels for a transport aircraft are presented. Each panel has two window cutouts and three frames and utilizes a distinctly different structural concept. These panels have been evaluated with internal pressure loads that generate biaxial tension loading conditions. Design limit load and design ultimate load tests have been performed on both panels. One of the sandwich panels was tested with the middle frame removed to demonstrate the suitability of this two-frame design for supporting the prescribed biaxial loading conditions with twice the initial frame spacing of 20 inches. A damage tolerance study was conducted on the two-frame panel by cutting a notch in the panel that originates at the edge of a cutout and extends in the panel hoop direction through the window-belt area. This panel with a notch was tested in a combined-load condition to demonstrate the structural damage tolerance at the design limit load condition. Both the sandwich panel designs successfully satisfied all desired load requirements in the experimental part of the study, and experimental results from the two-frame panel with and without damage are fully explained by the analytical results. The results of this study suggest that there is potential for using sandwich structural concepts with greater than the usual 20-in. wide frame spacing to further reduce aircraft fuselage structural weight.
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Applications of space teleoperator technology to the problems of the handicapped
NASA Technical Reports Server (NTRS)
Malone, T. B.; Deutsch, S.; Rubin, G.; Shenk, S. W.
1973-01-01
The identification of feasible and practical applications of space teleoperator technology for the problems of the handicapped were studied. A teleoperator system is defined by NASA as a remotely controlled, cybernetic, man-machine system designed to extend and augment man's sensory, manipulative, and locomotive capabilities. Based on a consideration of teleoperator systems, the scope of the study was limited to an investigation of these handicapped persons limited in sensory, manipulative, and locomotive capabilities. If the technology being developed for teleoperators has any direct application, it must be in these functional areas. Feasible and practical applications of teleoperator technology for the problems of the handicapped are described, and design criteria are presented with each application. A development plan is established to bring the application to the point of use.
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Implications of privacy needs and interpersonal distancing mechanisms for space station design
NASA Technical Reports Server (NTRS)
Harrison, Albert A.; Sommer, Robert; Struthers, Nancy; Hoyt, Kathleen
1988-01-01
Isolation, confinement, and the characteristics of microgravity will accentuate the need for privacy in the proposed NASA space station, yet limit the mechanism available for achieving it. This study proposes a quantitative model for understanding privacy, interpersonal distancing, and performance, and discusses the practical implications for Space Station design. A review of the relevant literature provided the basis for a database, definitions of physical and psychological distancing, loneliness, and crowding, and a quantitative model of situational privacy. The model defines situational privacy (the match between environment and task), and focuses on interpersonal contact along visual, auditory, olfactory, and tactile dimensions. It involves summing across pairs of crew members, contact dimensions, and time, yet also permits separate analyses of subsets of crew members and contact dimensions. The study concludes that performance will benefit when the type and level of contact afforded by the environment align with that required by the task. The key to achieving this is to design a flexible, definable, and redefinable interior environment that provides occupants with a wide array of options to meet their needs for solitude, limited social interaction, and open group activity. The report presents 49 recommendations in five categories to promote a wide range of privacy options despite the space station's volumetric limitations.
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Foret-Bruno, J Y; Trosseille, X; Page, Y; Huère, J F; Le Coz, J Y; Bendjellal, F; Diboine, A; Phalempin, T; Villeforceix, D; Baudrit, P; Guillemot, H; Coltat, J C
2001-11-01
In France, as in other countries, accident research studies show that a large proportion of restrained occupants who sustain severe or fatal injuries are involved in frontal impacts (65% and 50%, respectively). In severe frontal impacts with restrained occupants and where intrusion is not preponderant, the oldest occupants very often sustain severe thoracic injuries due to the conventional seat belt. As we have been observing over the last years, we will expect in the coming years developments which include more solidly-built cars, as offset crash test procedures are widely used to evaluate the passive safety of production vehicles. The reduction of intrusion for the most severe frontal impacts, through optimization of car deformation, usually translates into an increase in restraint forces and hence thoracic injury risk with a conventional retractor seat belt for a given impact severity. It is, therefore essential to limit the restraint forces exerted by the seat belt on the thorax in order to reduce the number of road casualties. In order to address thoracic injury risk in frontal impact, Renault cars have been equipped with the Programmed Restraint System (PRS) since 1995. The PRS is a restraint system that combines belt load limitation and pyrotechnic belt pretension. In an initial design of the Programmed Restraint System (PRS1), the belt load limiter was a steel component designed to shear at a given shoulder force, namely 6 kN. It was mounted between the retractor and the lower anchorage point of the belt. The design of the PRS was modified in 1998 (PRS2), but the principle of load limitation was maintained. The threshold was decreased to 4 kN and this lower belt belt-force limiter has been combined with a specially designed airbag. This paper reports on 347 real-world frontal accidents where the EES (Equivalent Energy Speed) ranged from 35 to 75 km/h. One hundred and ninety-eight (198) of these accidents involved cars equipped with the 6 kN load limiter, and 149 involved cars equipped with the 4 kN load limiter. Based on this accident data, the study compares the thoracic injury risk for two occupant populations: belted occupants involved in accidents in which the vehicle was not equipped with a load limiter (378 cases with pyrotechnic pretensioners), and belted occupants involved in accidents in which the vehicles were equipped with 4 or 6 kN load limiters and pyrotechnic pretensioners (347 cases). One observes that a 4 kN load limitation results in a very important reduction of thoracic injury risk for all AIS levels, compared to others samples. 50 to 60% reduction for AIS 2+ was observed, as well as 75 to 85% for AIS 3+. The complete absence of AIS 4+ with a 4 kN load limiter must be stressed, though it remains more than 8% for the other samples (no limiter and 6 kN limiter).
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Considerations of study design.
Koretz, Ronald L
2007-12-01
Research projects attempt to answer specific questions. The particular study design that is selected will depend in large measure on the nature of the question and the time and resources available. There are 5 common categories of clinical questions; they relate to etiology, prognosis, utility of diagnostic tests, efficacy of proposed interventions, and cost of treatment in specific disease states. A number of study designs can be used. Case reports serve to memorialize unusual or novel aspects of diseases. Retrospective case series are useful for defining natural history. Case-control studies are used by epidemiologists to elucidate potential etiologies of diseases. Prospective cohort studies can be used to assess natural history or to assess potential disease etiologies. Controlled trials are designed to assess the efficacy of therapeutic interventions. Studies that define the sensitivity and specificity of diagnostic tests can be used to assess the utility of those tests. Economic analyses estimate the costs that particular diseases or therapies will require. Each of these study designs has limitations; with the exception of high-quality randomized trials, none of these study designs can establish a causative relationship between putative etiologic (or therapeutic) factors and disease (outcomes).
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Combining band recovery data and Pollock's robust design to model temporary and permanent emigration
Lindberg, M.S.; Kendall, W.L.; Hines, J.E.; Anderson, M.G.
2001-01-01
Capture-recapture models are widely used to estimate demographic parameters of marked populations. Recently, this statistical theory has been extended to modeling dispersal of open populations. Multistate models can be used to estimate movement probabilities among subdivided populations if multiple sites are sampled. Frequently, however, sampling is limited to a single site. Models described by Burnham (1993, in Marked Individuals in the Study of Bird Populations, 199-213), which combined open population capture-recapture and band-recovery models, can be used to estimate permanent emigration when sampling is limited to a single population. Similarly, Kendall, Nichols, and Hines (1997, Ecology 51, 563-578) developed models to estimate temporary emigration under Pollock's (1982, Journal of Wildlife Management 46, 757-760) robust design. We describe a likelihood-based approach to simultaneously estimate temporary and permanent emigration when sampling is limited to a single population. We use a sampling design that combines the robust design and recoveries of individuals obtained immediately following each sampling period. We present a general form for our model where temporary emigration is a first-order Markov process, and we discuss more restrictive models. We illustrate these models with analysis of data on marked Canvasback ducks. Our analysis indicates that probability of permanent emigration for adult female Canvasbacks was 0.193 (SE = 0.082) and that birds that were present at the study area in year i - 1 had a higher probability of presence in year i than birds that were not present in year i - 1.
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Discussing study limitations in reports of biomedical studies- the need for more transparency.
Puhan, Milo A; Akl, Elie A; Bryant, Dianne; Xie, Feng; Apolone, Giovanni; ter Riet, Gerben
2012-02-23
Unbiased and frank discussion of study limitations by authors represents a crucial part of the scientific discourse and progress. In today's culture of publishing many authors or scientific teams probably balance 'utter honesty' when discussing limitations of their research with the risk of being unable to publish their work. Currently, too few papers in the medical literature frankly discuss how limitations could have affected the study findings and interpretations. The goals of this commentary are to review how limitations are currently acknowledged in the medical literature, to discuss the implications of limitations in biomedical studies, and to make suggestions as to how to openly discuss limitations for scientists submitting their papers to journals. This commentary was developed through discussion and logical arguments by the authors who are doing research in the area of hedging (use of language to express uncertainty) and who have extensive experience as authors and editors of biomedical papers. We strongly encourage authors to report on all potentially important limitations that may have affected the quality and interpretation of the evidence being presented. This will not only benefit science but also offers incentives for authors: If not all important limitations are acknowledged readers and reviewers of scientific articles may perceive that the authors were unaware of them. Authors should take advantage of their content knowledge and familiarity with the study to prevent misinterpretations of the limitations by reviewers and readers. Articles discussing limitations help shape the future research agenda and are likely to be cited because they have informed the design and conduct of future studies. Instead of perceiving acknowledgment of limitations negatively, authors, reviewers and editors should recognize the potential of a frank and unbiased discussion of study limitations that should not jeopardize acceptance of manuscripts.
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Experimental Design for Hanford Low-Activity Waste Glasses with High Waste Loading
DOE Office of Scientific and Technical Information (OSTI.GOV)
Piepel, Gregory F.; Cooley, Scott K.; Vienna, John D.
This report discusses the development of an experimental design for the initial phase of the Hanford low-activity waste (LAW) enhanced glass study. This report is based on a manuscript written for an applied statistics journal. Appendices A, B, and E include additional information relevant to the LAW enhanced glass experimental design that is not included in the journal manuscript. The glass composition experimental region is defined by single-component constraints (SCCs), linear multiple-component constraints (MCCs), and a nonlinear MCC involving 15 LAW glass components. Traditional methods and software for designing constrained mixture experiments with SCCs and linear MCCs are not directlymore » applicable because of the nonlinear MCC. A modification of existing methodology to account for the nonlinear MCC was developed and is described in this report. One of the glass components, SO 3, has a solubility limit in glass that depends on the composition of the balance of the glass. A goal was to design the experiment so that SO 3 would not exceed its predicted solubility limit for any of the experimental glasses. The SO 3 solubility limit had previously been modeled by a partial quadratic mixture model expressed in the relative proportions of the 14 other components. The partial quadratic mixture model was used to construct a nonlinear MCC in terms of all 15 components. In addition, there were SCCs and linear MCCs. This report describes how a layered design was generated to (i) account for the SCCs, linear MCCs, and nonlinear MCC and (ii) meet the goals of the study. A layered design consists of points on an outer layer, and inner layer, and a center point. There were 18 outer-layer glasses chosen using optimal experimental design software to augment 147 existing glass compositions that were within the LAW glass composition experimental region. Then 13 inner-layer glasses were chosen with the software to augment the existing and outer-layer glasses. The experimental design was completed by a center-point glass, a Vitreous State Laboratory glass, and replicates of the center point and Vitreous State Laboratory glasses.« less
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Parameter Design and Optimal Control of an Open Core Flywheel Energy Storage System
NASA Technical Reports Server (NTRS)
Pang, D.; Anand, D. K.; Kirk, J. A.
1996-01-01
In low earth orbit (LEO) satellite applications spacecraft power is provided by photovoltaic cells and batteries. To overcome battery shortcomings the University of Maryland, working in cooperation with NASA/GSFC and NASA/LeRC, has developed a magnetically suspended flywheel for energy storage applications. The system is referred to as an Open Core Composite Flywheel (OCCF) energy storage system. Successful application of flywheel energy storage requires integration of several technologies, viz. bearings, rotor design, motor/generator, power conditioning, and system control. In this paper we present a parameter design method which has been developed for analyzing the linear SISO model of the magnetic bearing controller for the OCCF. The objective of this continued research is to principally analyze the magnetic bearing system for nonlinear effects in order to increase the region of stability, as determined by high speed and large air gap control. This is achieved by four tasks: (1) physical modeling, design, prototyping, and testing of an improved magnetically suspended flywheel energy storage system, (2) identification of problems that limit performance and their corresponding solutions, (3) development of a design methodology for magnetic bearings, and (4) design of an optimal controller for future high speed applications. Both nonlinear SISO and MIMO models of the magnetic system were built to study limit cycle oscillations and power amplifier saturation phenomenon observed in experiments. The nonlinear models include the inductance of EM coils, the power amplifier saturation, and the physical limitation of the flywheel movement as discussed earlier. The control program EASY5 is used to study the nonlinear SISO and MIMO models. Our results have shown that the characteristics and frequency responses of the magnetic bearing system obtained from modeling are comparable to those obtained experimentally. Although magnetic saturation is shown in the bearings, there are good correlations between the theoretical model and experimental data. Both simulation and experiment confirm large variations of the magnetic bearing characteristics due to air gap growth. Therefore, the gap growth effect should be considered in the magnetic bearing system design. Additionally, the magnetic bearing control system will be compared to other design methods using not only parameter design but H-infinity optimal control and mu synthesis.
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Shen, Jenny I; Lum, Erik L; Chang, Tara I
2016-09-01
Because large randomized clinical trials (RCTs) in dialysis have been relatively scarce, evidence-based dialysis care has depended heavily on the results of observational studies. However, when results from RCTs appear to contradict the findings of observational studies, nephrologists are left to wonder which type of study they should believe. In this editorial, we explore the key differences between observational studies and RCTs in the context of such seemingly conflicting studies in dialysis. Confounding is the major limitation of observational studies, whereas low statistical power and problems with external validity are more likely to limit the findings of RCTs. Differences in the specification of the population, exposure, and outcomes can also contribute to different results among RCTs and observational studies. Rigorous methods are required regardless of what type of study is conducted, and readers should not automatically assume that one type of study design is superior to the other. Ultimately, dialysis care requires both well-designed, well-conducted observational studies and RCTs to move the field forward. © 2016 Wiley Periodicals, Inc.
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Shen, Jenny I.; Lum, Erik L.; Chang, Tara I.
2016-01-01
Because large randomized clinical trials (RCTs) in dialysis have been relatively scarce, evidence-based dialysis care has depended heavily on the results of observational studies. However, when results from RCTs appear to contradict the findings of observational studies, nephrologists are left to wonder which type of study they should believe. In this editorial we explore the key differences between observational studies and RCTs in the context of such seemingly conflicting studies in dialysis. Confounding is the major limitation of observational studies, while low statistical power and problems with external validity are more likely to limit the findings of RCTs. Differences in the specification of the population, exposure, and outcomes can also contribute to different results among RCTs and observational studies. Rigorous methods are required regardless of what type of study is conducted, and readers should not automatically assume that one type of study design is superior to the other. Ultimately, dialysis care requires both well-designed, well-conducted observational studies and RCTs to move the field forward. PMID:27207819
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Design of an Eye Limiting Resolution Visual System Using Commercial-Off-the-Shelf Equipment
NASA Technical Reports Server (NTRS)
Sweet, Barbara T.; Giovannetti, Dean P.
2008-01-01
A feasibility study was conducted to determine if a flight simulator with an eye-limiting resolution out-the-window (OTW) visual system could be built using commercial off-the-shelf (COTS) technology and used to evaluate the visual performance of Air Force pilots in an operations context. Results of this study demonstrate that an eye limiting OTW visual system can be built using COTS technology. Further, a series of operationally-based tasks linked to clinical vision tests can be used within the synthetic environment to demonstrate a correlation and quantify the level of correlation between vision and operational aviation performance.
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Quality improvement nursing facilities: a nursing leadership perspective.
Adams-Wendling, Linda; Lee, Robert
2005-11-01
The purposes of this study were to characterize the state of quality improvement (QI) in nursing facilities and to identify barriers to improvement from nursing leaders' perspectives. The study employed a non-experimental descriptive design, using closed- and open-ended survey questions in a sample of 51 nursing facilities in a midwestern state. Only two of these facilities had active QI programs. Furthermore, turnover and limited training among these nursing leaders represented major barriers to rapid implementation of such programs. This study is consistent with earlier findings that QI programs are limited in nursing homes.
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Optimal design study of high efficiency indium phosphide space solar cells
NASA Technical Reports Server (NTRS)
Jain, Raj K.; Flood, Dennis J.
1990-01-01
Recently indium phosphide solar cells have achieved beginning of life AMO efficiencies in excess of 19 pct. at 25 C. The high efficiency prospects along with superb radiation tolerance make indium phosphide a leading material for space power requirements. To achieve cost effectiveness, practical cell efficiencies have to be raised to near theoretical limits and thin film indium phosphide cells need to be developed. The optimal design study is described of high efficiency indium phosphide solar cells for space power applications using the PC-1D computer program. It is shown that cells with efficiencies over 22 pct. AMO at 25 C could be fabricated by achieving proper material and process parameters. It is observed that further improvements in cell material and process parameters could lead to experimental cell efficiencies near theoretical limits. The effect of various emitter and base parameters on cell performance was studied.
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Geopotential research mission, science, engineering and program summary
NASA Technical Reports Server (NTRS)
Keating, T. (Editor); Taylor, P. (Editor); Kahn, W. (Editor); Lerch, F. (Editor)
1986-01-01
This report is based upon the accumulated scientific and engineering studies pertaining to the Geopotential Research Mission (GRM). The scientific need and justification for the measurement of the Earth's gravity and magnetic fields are discussed. Emphasis is placed upon the studies and conclusions of scientific organizations and NASA advisory groups. The engineering design and investigations performed over the last 4 years are described, and a spacecraft design capable of fulfilling all scientific objectives is presented. In addition, critical features of the scientific requirements and state-of-the-art limitations of spacecraft design, mission flight performance, and data processing are discussed.
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NASA Technical Reports Server (NTRS)
Brooks, George W.
1985-01-01
The options for the design, construction, and testing of a dynamic model of the space station were evaluated. Since the definition of the space station structure is still evolving, the Initial Operating Capacity (IOC) reference configuration was used as the general guideline. The results of the studies treat: general considerations of the need for and use of a dynamic model; factors which deal with the model design and construction; and a proposed system for supporting the dynamic model in the planned Large Spacecraft Laboratory.
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Bowden, Jack; Relton, Caroline; Davey Smith, George
2016-01-01
Mendelian randomization (MR) is an increasingly important tool for appraising causality in observational epidemiology. The technique exploits the principle that genotypes are not generally susceptible to reverse causation bias and confounding, reflecting their fixed nature and Mendel’s first and second laws of inheritance. The approach is, however, subject to important limitations and assumptions that, if unaddressed or compounded by poor study design, can lead to erroneous conclusions. Nevertheless, the advent of 2-sample approaches (in which exposure and outcome are measured in separate samples) and the increasing availability of open-access data from large consortia of genome-wide association studies and population biobanks mean that the approach is likely to become routine practice in evidence synthesis and causal inference research. In this article we provide an overview of the design, analysis, and interpretation of MR studies, with a special emphasis on assumptions and limitations. We also consider different analytic strategies for strengthening causal inference. Although impossible to prove causality with any single approach, MR is a highly cost-effective strategy for prioritizing intervention targets for disease prevention and for strengthening the evidence base for public health policy. PMID:26961927
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Feasibility study of patient-specific surgical templates for the fixation of pedicle screws.
Salako, F; Aubin, C-E; Fortin, C; Labelle, H
2002-01-01
Surgery for scoliosis, as well as other posterior spinal surgeries, frequently uses pedicle screws to fix an instrumentation on the spine. Misplacement of a screw can lead to intra- and post-operative complications. The objective of this study is to design patient-specific surgical templates to guide the drilling operation. From the CT-scan of a vertebra, the optimal drilling direction and limit angles are computed from an inverse projection of the pedicle limits. The first template design uses a surface-to-surface registration method and was constructed in a CAD system by subtracting the vertebra from a rectangular prism and a cylinder with the optimal orientation. This template and the vertebra were built using rapid prototyping. The second design uses a point-to-surface registration method and has 6 adjustable screws to adjust the orientation and length of the drilling support device. A mechanism was designed to hold it in place on the spinal process. A virtual prototype was build with CATIA software. During the operation, the surgeon places either template on patient's vertebra until a perfect match is obtained before drilling. The second design seems better than the first one because it can be reused on different vertebra and is less sensible to registration errors. The next step is to build the second design and make experimental and simulations tests to evaluate the benefits of this template during a scoliosis operation.
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Postpolio Syndrome: Using a Single Case Study
ERIC Educational Resources Information Center
Obringer, S. John; Elrod, G. Franklin
2004-01-01
The purpose of this study was to identify the major characteristics of postpolio syndrome (PPS), investigate physical and psychological limitations, and comprehensively review current medical interventions through a single subject design. The study addresses the symptoms and characteristics, the effect on life style, and the current recommended…
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Yao, Chu K; Gibson, Peter R; Shepherd, Susan J
2013-05-01
Clear guiding principles for the design and conduct of dietary intervention trials in functional gastrointestinal disorders (FGID) are lacking. This narrative review examines the specific challenges associated with the design and reporting in dietary intervention trials. Dietary intervention trials need to address the collinearity between food, nutrients, and bioactive components that obscure the relationship between food and their effects in the gut. Randomized, double-blinded, placebo-controlled studies remain the gold standard for dietary trials, but are limited by difficulties in adequate masking of study food or inappropriate choice of placebo food/diets. Provision of study diets as the preferred delivery method can somewhat address these limitations, although allowing good adherence compared with education-based dietary interventions. Issues associated with participant expectancies and dietary behaviors can alter the true effectiveness of a diet. In addition, failure to adjust for or report baseline intake of nutrients of interest can reduce their magnitude of benefit. Bias in subjective reports and choice of measurement tools can preclude accurate assessment of food-intake data. In the design of elimination and rechallenge studies, sufficient time period and adequate exclusion of dietary triggers are essential to ensure symptoms are well-controlled before rechallenging. The route and frequency of challenging, design of test food, and/or placebo should match the aims of the rechallenge phase. Long-term efficacy data of such therapeutic diets has been poorly documented in most studies. Standardized guidelines that address many of the challenges outlined above are suggested to strengthen the quality of evidence for dietary therapies in FGID.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Dr. Pavel V. Tsvetkov
2009-05-20
This project assessed the advantages and limitations of using minor actinides as a fuel component to achieve ultra-long life Very High Temperature Reactor (VHTR) configurations. Researchers considered and compared the capabilities of pebble-bed and prismatic core designs with advanced actinide fuels to achieve ultra-long operation without refueling. Since both core designs permit flexibility in component configuration, fuel utilization, and fuel management, it is possible to improve fissile properties of minor actinides by neutron spectrum shifting through configuration adjustments. The project studied advanced actinide fuels, which could reduce the long-term radio-toxicity and heat load of high-level waste sent to a geologicmore » repository and enable recovery of the energy contained in spent fuel. The ultra-long core life autonomous approach may reduce the technical need for additional repositories and is capable to improve marketability of the Generation IV VHTR by allowing worldwide deployment, including remote regions and regions with limited industrial resources. Utilization of minor actinides in nuclear reactors facilitates developments of new fuel cycles towards sustainable nuclear energy scenarios.« less
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A firefly algorithm for optimum design of new-generation beams
NASA Astrophysics Data System (ADS)
Erdal, F.
2017-06-01
This research addresses the minimum weight design of new-generation steel beams with sinusoidal openings using a metaheuristic search technique, namely the firefly method. The proposed algorithm is also used to compare the optimum design results of sinusoidal web-expanded beams with steel castellated and cellular beams. Optimum design problems of all beams are formulated according to the design limitations stipulated by the Steel Construction Institute. The design methods adopted in these publications are consistent with BS 5950 specifications. The formulation of the design problem considering the above-mentioned limitations turns out to be a discrete programming problem. The design algorithms based on the technique select the optimum universal beam sections, dimensional properties of sinusoidal, hexagonal and circular holes, and the total number of openings along the beam as design variables. Furthermore, this selection is also carried out such that the behavioural limitations are satisfied. Numerical examples are presented, where the suggested algorithm is implemented to achieve the minimum weight design of these beams subjected to loading combinations.
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Outcomes of the Bobath concept on upper limb recovery following stroke.
Luke, Carolyn; Dodd, Karen J; Brock, Kim
2004-12-01
To determine the effectiveness of the Bobath concept at reducing upper limb impairments, activity limitations and participation restrictions after stroke. Electronic databases were searched to identify relevant trials published between 1966 and 2003. Two reviewers independently assessed articles for the following inclusion criteria: population of adults with upper limb disability after stroke; stated use of the Bobath concept aimed at improving upper limb disability in isolation from other approaches; outcomes reflecting changes in upper limb impairment, activity limitation or participation restriction. Of the 688 articles initially identified, eight met the inclusion criteria. Five were randomized controlled trials, one used a single-group crossover design and two were single-case design studies. Five studies measured impairments including shoulder pain, tone, muscle strength and motor control. The Bobath concept was found to reduce shoulder pain better than cryotherapy, and to reduce tone compared to no intervention and compared to proprioceptive neuromuscular facilitation (PNF). However, no difference was detected for changes in tone between the Bobath concept and a functional approach. Differences did not reach significance for measures of muscle strength and motor control. Six studies measured activity limitations, none of these found the Bobath concept was superior to other therapy approaches. Two studies measured changes in participation restriction and both found equivocal results. Comparisons of the Bobath concept with other approaches do not demonstrate superiority of one approach over the other at improving upper limb impairment, activity or participation. However, study limitations relating to methodological quality, the outcome measures used and contextual factors investigated limit the ability to draw conclusions. Future research should use sensitive upper limb measures, trained Bobath therapists and homogeneous samples to identify the influence of patient factors on the response to therapy approaches.
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Spectrally And Temporally Resolved Low-Light Level Video Microscopy
NASA Astrophysics Data System (ADS)
Wampler, John E.; Furukawa, Ruth; Fechheimer, Marcus
1989-12-01
The IDG law-light video microscope system was designed to aid studies of localization of subcellular luminescence sources and stimulus/response coupling in single living cells using luminescent probes. Much of the motivation for design of this instrument system came from the pioneering efforts of Dr. Reynolds (Reynolds, Q. Rev. Biophys. 5, 295-347; Reynolds and Taylor, Bioscience 30, 586-592) who showed the value of intensified video camera systems for detection and localizion of fluorescence and bioluminescence signals from biological tissues. Our instrument system has essentially two roles, 1) localization and quantitation of very weak bioluminescence signals and 2) quantitation of intracellular environmental characteristics such as pH and calcium ion concentrations using fluorescent and bioluminescent probes. The instrument system exhibits over one million fold operating range allowing visualization and enhancement of quantum limited images with quantum limited response, spectral analysis of fluorescence signals, and transmitted light imaging. The computer control of the system implements rapid switching between light regimes, spatially resolved spectral scanning, and digital data processing for spectral shape analysis and for detailed analysis of the statistical distribution of single cell measurements. The system design and software algorithms used by the system are summarized. These design criteria are illustrated with examples taken from studies of bioluminescence, applications of bioluminescence to study developmental processes and gene expression in single living cells, and applications of fluorescent probes to study stimulus/response coupling in living cells.
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GeneratorSE: A Sizing Tool for Variable-Speed Wind Turbine Generators
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sethuraman, Latha; Dykes, Katherine L
This report documents a set of analytical models employed by the optimization algorithms within the GeneratorSE framework. The initial values and boundary conditions employed for the generation of the various designs and initial estimates for basic design dimensions, masses, and efficiency for the four different models of generators are presented and compared with empirical data collected from previous studies and some existing commercial turbines. These models include designs applicable for variable-speed, high-torque application featuring direct-drive synchronous generators and low-torque application featuring induction generators. In all of the four models presented, the main focus of optimization is electromagnetic design with themore » exception of permanent-magnet and wire-wound synchronous generators, wherein the structural design is also optimized. Thermal design is accommodated in GeneratorSE as a secondary attribute by limiting the winding current densities to acceptable limits. A preliminary validation of electromagnetic design was carried out by comparing the optimized magnetic loading against those predicted by numerical simulation in FEMM4.2, a finite-element software for analyzing electromagnetic and thermal physics problems for electrical machines. For direct-drive synchronous generators, the analytical models for the structural design are validated by static structural analysis in ANSYS.« less
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Placement of English as a Second Language (ESL) Student Learners in Higher Education
ERIC Educational Resources Information Center
Banegas, Michael R.
2013-01-01
Immigration into the U.S. will continue to increase in the coming years, thereby increasing the postsecondary enrollment of ESL students. Yet there is still a limited amount of research designed to evaluate which ESL placement programs are most effective. This study was designed to determine if the use of correct testing instruments would ensure…
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ERIC Educational Resources Information Center
Krause, George A.; Lewis, David E.; Douglas, James W.
2013-01-01
Governments make policy decisions in the same areas in quite different institutions. Some assign policymaking responsibility to institutions designed to be insulated from myopic partisan and electoral pressures and others do not. In this study, we claim that differences in political context and institutional design constrain the policy choices…
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Six Criteria for Survey Sample Design Evaluation.
ERIC Educational Resources Information Center
Wang, Lin; Fan, Xitao
The popularity of the sample survey in educational research makes it necessary for consumers to tell a good study from a poor one. Several sources were identified that gave advice on how to evaluate a sample design. The sources are either limited or too extensive to use in a practical sense. The purpose of this paper is to recommend six important…
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ERIC Educational Resources Information Center
Ercikan, Kadriye; Roth, Wolff-Michael
2014-01-01
Context: Generalization is a critical concept in all research designed to generate knowledge that applies to all elements of a unit (population) while studying only a subset of these elements (sample). Commonly applied criteria for generalizing focus on experimental design or representativeness of samples of the population of units. The criteria…
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ERIC Educational Resources Information Center
Whatley Blum, Janet E.; Davee, Anne-Marie; Beaudoin, Christina M.; Jenkins, Paul L.; Kaley, Lori A.; Wigand, Debra A.
2008-01-01
Objective: To examine change in high school students' beverage consumption patterns pre- and post-intervention of reduced availability of sugar-sweetened beverages (SSB) and diet soda in school food venues. Design: A prospective, quasi-experimental, nonrandomized study design. Setting: Public high schools. Participants: A convenience sample from…
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ERIC Educational Resources Information Center
Kelley, Elizabeth Spencer; Goldstein, Howard; Spencer, Trina D.; Sherman, Amber
2015-01-01
This early efficacy study examined the effects of an automated storybook intervention designed to promote school readiness among at-risk prekindergarten children. Story Friends is a small-group intervention in which vocabulary and question-answering lessons are embedded in a series of storybooks.A randomized group design with an embedded…
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17 CFR 1.73 - Clearing futures commission merchant risk management.
Code of Federal Regulations, 2014 CFR
2014-04-01
... maintain systems of risk controls reasonably designed to ensure compliance with the limits; (iii) When a... for clearing, it shall establish and maintain systems of risk management controls reasonably designed... maintain systems of risk management controls reasonably designed to ensure compliance with the limits. (v...
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17 CFR 1.73 - Clearing futures commission merchant risk management.
Code of Federal Regulations, 2013 CFR
2013-04-01
... maintain systems of risk controls reasonably designed to ensure compliance with the limits; (iii) When a... for clearing, it shall establish and maintain systems of risk management controls reasonably designed... maintain systems of risk management controls reasonably designed to ensure compliance with the limits. (v...
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Nierenberg, Andrew A.; Sylvia, Louisa G.; Leon, Andrew C.; Reilly-Harrington, Noreen; Shesler, Leah W.; McElroy, Susan L.; Friedman, Edward S.; Thase, Michael E.; Shelton, Richard C.; Bowden, Charles; Tohen, Mauricio; Singh, Vivek; Deckersbach, Thilo; Ketter, Terence; Kocsis, James; McInnis, Melvin G.; Schoenfeld, David; Bobo, William V.; Calabrese, Joseph R.
2015-01-01
Background Classic and second generation antipsychotic mood stabilizers are recommended for treatment of bipolar disorder, yet there are no randomized comparative effectiveness studies that have examined the “real-world” advantages and disadvantages of these medications Purpose We describe the strategic decisions in the design of the Clinical and Health Outcomes Initiative in Comparative Effectiveness for Bipolar Disorder (Bipolar CHOICE). This paper outlines the key issues and solutions the investigators faced in designing a clinical trial that would maximize generalizability and inform real-world clinical treatment of bipolar disorder. Methods Bipolar CHOICE was a 6-month, multi-site, prospective, randomized clinical trial of outpatients with bipolar disorder. This study compares the effectiveness of quetiapine versus lithium, each with adjunctive personalized treatments. The co-primary outcomes selected are the overall benefits and harms of the study medications (as measured by the Clinical Global Impression-Efficacy Index) and the Necessary Clinical Adjustments (a measure of the number of medication changes). Secondary outcomes are continuous measures of mood, the Framingham General Cardiovascular Risk Score and the Longitudinal Interval Follow up Evaluation Range of Impaired Functioning Tool. Results The final study design consisted of a single-blind, randomized comparative effectiveness trial of quetiapine versus lithium, plus adjunctive personalized treatment (APT), across ten sites. Other important study considerations included limited exclusion criteria to maximize generalizability, flexible dosing of APT medications to mimic real-world treatment, and an intent-to-treat analysis plan. 482 participants were randomized to the study and 364 completed. Limitations The potential limitations of the study include the heterogeneity of APT, selection of study medications, lack of a placebo-control group, and participants’ ability to pay for study medications. Conclusion We expect that this study will inform our understanding of the benefits and harms of lithium, a classic mood stabilizer, compared to quetiapine, a second generation antipsychotic with broad-spectrum activity in bipolar disorder and will provide an example of a well-designed and well-conducted randomized comparative effectiveness clinical trial. PMID:24346608
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Design and analysis of multiple diseases genome-wide association studies without controls.
Chen, Zhongxue; Huang, Hanwen; Ng, Hon Keung Tony
2012-11-15
In genome-wide association studies (GWAS), multiple diseases with shared controls is one of the case-control study designs. If data obtained from these studies are appropriately analyzed, this design can have several advantages such as improving statistical power in detecting associations and reducing the time and cost in the data collection process. In this paper, we propose a study design for GWAS which involves multiple diseases but without controls. We also propose corresponding statistical data analysis strategy for GWAS with multiple diseases but no controls. Through a simulation study, we show that the statistical association test with the proposed study design is more powerful than the test with single disease sharing common controls, and it has comparable power to the overall test based on the whole dataset including the controls. We also apply the proposed method to a real GWAS dataset to illustrate the methodologies and the advantages of the proposed design. Some possible limitations of this study design and testing method and their solutions are also discussed. Our findings indicate that the proposed study design and statistical analysis strategy could be more efficient than the usual case-control GWAS as well as those with shared controls. Copyright © 2012 Elsevier B.V. All rights reserved.
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Thermosyphon Flooding in Reduced Gravity Environments
NASA Technical Reports Server (NTRS)
Gibson, Marc Andrew
2013-01-01
An innovative experiment to study the thermosyphon flooding limits was designed and flown on aparabolic flight campaign to achieve the Reduced Gravity Environments (RGE) needed to obtainempirical data for analysis. Current correlation models of Faghri and Tien and Chung do not agreewith the data. A new model is presented that predicts the flooding limits for thermosyphons inearths gravity and lunar gravity with a 95 confidence level of +- 5W.
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Johnson, Lucas B; Gintner, Lucas P; Park, Sehoo; Snow, Christopher D
2015-08-01
Accuracy of current computational protein design (CPD) methods is limited by inherent approximations in energy potentials and sampling. These limitations are often used to qualitatively explain design failures; however, relatively few studies provide specific examples or quantitative details that can be used to improve future CPD methods. Expanding the design method to include a library of sequences provides data that is well suited for discriminating between stabilizing and destabilizing design elements. Using thermophilic endoglucanase E1 from Acidothermus cellulolyticus as a model enzyme, we computationally designed a sequence with 60 mutations. The design sequence was rationally divided into structural blocks and recombined with the wild-type sequence. Resulting chimeras were assessed for activity and thermostability. Surprisingly, unlike previous chimera libraries, regression analysis based on one- and two-body effects was not sufficient for predicting chimera stability. Analysis of molecular dynamics simulations proved helpful in distinguishing stabilizing and destabilizing mutations. Reverting to the wild-type amino acid at destabilized sites partially regained design stability, and introducing predicted stabilizing mutations in wild-type E1 significantly enhanced thermostability. The ability to isolate stabilizing and destabilizing elements in computational design offers an opportunity to interpret previous design failures and improve future CPD methods. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
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Hodek, Ondřej; Křížek, Tomáš; Coufal, Pavel; Ryšlavá, Helena
2017-03-01
In this study, we optimized a method for the determination of free amino acids in Nicotiana tabacum leaves. Capillary electrophoresis with contactless conductivity detector was used for the separation of 20 proteinogenic amino acids in acidic background electrolyte. Subsequently, the conditions of extraction with HCl were optimized for the highest extraction yield of the amino acids because sample treatment of plant materials brings some specific challenges. Central composite face-centered design with fractional factorial design was used in order to evaluate the significance of selected factors (HCl volume, HCl concentration, sonication, shaking) on the extraction process. In addition, the composite design helped us to find the optimal values for each factor using the response surface method. The limits of detection and limits of quantification for the 20 proteinogenic amino acids were found to be in the order of 10 -5 and 10 -4 mol l -1 , respectively. Addition of acetonitrile to the sample was tested as a method commonly used to decrease limits of detection. Ambiguous results of this experiment pointed out some features of plant extract samples, which often required specific approaches. Suitability of the method for metabolomic studies was tested by analysis of a real sample, in which all amino acids, except for L-methionine and L-cysteine, were successfully detected. The optimized extraction process together with the capillary electrophoresis method can be used for the determination of proteinogenic amino acids in plant materials. The resulting inexpensive, simple, and robust method is well suited for various metabolomic studies in plants. As such, the method represents a valuable tool for research and practical application in the fields of biology, biochemistry, and agriculture.
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Varekar, Vikas; Karmakar, Subhankar; Jha, Ramakar
2016-02-01
The design of surface water quality sampling location is a crucial decision-making process for rationalization of monitoring network. The quantity, quality, and types of available dataset (watershed characteristics and water quality data) may affect the selection of appropriate design methodology. The modified Sanders approach and multivariate statistical techniques [particularly factor analysis (FA)/principal component analysis (PCA)] are well-accepted and widely used techniques for design of sampling locations. However, their performance may vary significantly with quantity, quality, and types of available dataset. In this paper, an attempt has been made to evaluate performance of these techniques by accounting the effect of seasonal variation, under a situation of limited water quality data but extensive watershed characteristics information, as continuous and consistent river water quality data is usually difficult to obtain, whereas watershed information may be made available through application of geospatial techniques. A case study of Kali River, Western Uttar Pradesh, India, is selected for the analysis. The monitoring was carried out at 16 sampling locations. The discrete and diffuse pollution loads at different sampling sites were estimated and accounted using modified Sanders approach, whereas the monitored physical and chemical water quality parameters were utilized as inputs for FA/PCA. The designed optimum number of sampling locations for monsoon and non-monsoon seasons by modified Sanders approach are eight and seven while that for FA/PCA are eleven and nine, respectively. Less variation in the number and locations of designed sampling sites were obtained by both techniques, which shows stability of results. A geospatial analysis has also been carried out to check the significance of designed sampling location with respect to river basin characteristics and land use of the study area. Both methods are equally efficient; however, modified Sanders approach outperforms FA/PCA when limited water quality and extensive watershed information is available. The available water quality dataset is limited and FA/PCA-based approach fails to identify monitoring locations with higher variation, as these multivariate statistical approaches are data-driven. The priority/hierarchy and number of sampling sites designed by modified Sanders approach are well justified by the land use practices and observed river basin characteristics of the study area.
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... cancer risk. Despite the limitations of the study designs, there is consistent evidence that higher amounts of ... the National Cancer Institute.” Please note that blog posts that are written by individuals from outside the ...
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Reply to Comment by Briere and Elliott.
ERIC Educational Resources Information Center
Nash, Michael R.; And Others
1993-01-01
Nash et al. respond to Briere and Elliott's (this issue) comments regarding their study (this issue) on effects of controlling for family environment when studying sexual abuse sequelae. Cites limitations of Briere and Elliott's survey study database. Agrees with Briere and Elliott in call for longitudinal, multimethod designs for examining…
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The Home Instruction Program for Preschool Youngsters (HIPPY).
ERIC Educational Resources Information Center
Baker, Amy J. L.; Piotrkowski, Chaya S.; Brooks-Gunn, Jeanne
1999-01-01
Describes the Home Instruction Program for Preschool Youngsters (HIPPY), a two-year home-based early-education intervention program designed to help parents with limited formal education prepare their children for school. Presents findings from a two-site HIPPY study, a one-site case study, and a three-site qualitative study. (SLD)
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One Size Fits All? Slow Cortical Potentials Neurofeedback: A Review
ERIC Educational Resources Information Center
Mayer, Kerstin; Wyckoff, Sarah N.; Strehl, Ute
2013-01-01
Objective: The intent of this manuscript was to review all published studies on slow cortical potentials (SCP) neurofeedback for the treatment of ADHD, with emphasis on neurophysiological rationale, study design, protocol, outcomes, and limitations. Method: For review, PubMed, MEDLINE, ERIC, and Google Scholar searches identified six studies and…
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NASA Technical Reports Server (NTRS)
Arnold, William, Sr.; Stahl, H Philip
2017-01-01
This design study was conducted to support the HABEX project. There are a number of companion papers at this conference which go into detail on what all the HABEX goals are. The objective of this paper is to establish a baseline primary mirror design which satisfies the following structural related requirements. The designs in this study have a high TRL (Technology Readiness Level), realistic manufacturing limits and performance in line with the HABEX mission. A secondary goal of the study was to evaluate a number competing criteria for the selection. Questions such as differences in the on axis versus off axis static and dynamic response to disturbances. This study concentrates on the structural behavior, companion papers cover thermal and long term stability aspects of the problem.
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NASA Astrophysics Data System (ADS)
Zhou, Hanying; Krist, John; Nemati, Bijan
2016-08-01
Current coronagraph instrument design (CGI), as a part of a proposed NASA WFIRST (Wide-Field InfraRed Survey Telescope) mission, allocates two subband filters per full science band in order to contain system complexity and cost. We present our detailed investigation results on the adequacy of such limited number of finite subband filters in achieving full band dark hole contrast with shaped pupil coronagraph. The study is based on diffraction propagation modeling with realistic WFIRST optics, where each subband's complex field estimation is obtained, using Electric Field Conjugation (EFC) wavefront sensing / control algorithm, from pairwise pupil plane deformable mirror (DM) probing and image plane intensity averaging of the resulting fields of multiple (subband) wavelengths. Multiple subband choices and probing and control strategies are explored, including standard subband probing; mixed wavelength and/or weighted Jacobian matrix; subband probing with intensity subtraction; and extended subband probing with intensity subtraction. Overall, the investigation shows that the achievable contrast with limited number of finite subband EFC probing is about 2 2.5x worse than the designed post-EFC contrast for current SPC design. The result suggests that for future shaped pupil design, slightly larger over intended full bandwidth should be considered if it will be used with limited subbands for probing.
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Thermal and cryogenic design study for space infrared telescope facility (SIRTF)
NASA Technical Reports Server (NTRS)
Urbach, A. R.; Kelly, T.; Poley, R.
1984-01-01
A study was conducted to determine the ability of an all superfluid helium design to meet the performance requirements of background limited to 200 micrometer, and a two year lifetime for a one meter class free flying infrared observatory. Both a 98 deg and 28.5 deg inclination orbits were examined, and aperture shade designs were developed for both orbits. A unique forebaffle cooling design significantly reduces the sensitivity to aperture heat loads. With certain restrictions on observing modes, the study determined that an all superfluid helium Dewar will meet the temperature and lifetime requirements. A dual cryogen SFHe/SH2 system was also investigated for the 28.5 deg orbit and found to provide a more constant forebaffle temperature but with only a slight improvement in lifetime.
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NASA Technical Reports Server (NTRS)
Hepler, A. K.; Zeck, H.; Walker, W. H.; Polack, A.
1982-01-01
Control requirements of Controlled Configured Design Approach vehicles with far-aft center of gravity locations are studied. The baseline system investigated is a fully reusable vertical takeoff/horizontal landing single stage-to-orbit vehicle with mission requirements similar to that of the space shuttle vehicle. Evaluations were made to determine dynamic stability boundaries, time responses, trim control, operational center-of-gravity limits, and flight control subsystem design requirements. Study tasks included a baseline vehicle analysis, an aft center of gravity study, a payload size study, and a technology assessment.
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48 CFR 1336.609-1 - Design within funding limitations.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Design within funding limitations. 1336.609-1 Section 1336.609-1 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1336.609-1 Design within funding...
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48 CFR 436.609-1 - Design within funding limitations.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 48 Federal Acquisition Regulations System 4 2012-10-01 2012-10-01 false Design within funding limitations. 436.609-1 Section 436.609-1 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.609-1 Design within funding...
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48 CFR 436.609-1 - Design within funding limitations.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 48 Federal Acquisition Regulations System 4 2013-10-01 2013-10-01 false Design within funding limitations. 436.609-1 Section 436.609-1 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.609-1 Design within funding...
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48 CFR 436.609-1 - Design within funding limitations.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false Design within funding limitations. 436.609-1 Section 436.609-1 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.609-1 Design within funding...
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48 CFR 1336.609-1 - Design within funding limitations.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Design within funding limitations. 1336.609-1 Section 1336.609-1 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1336.609-1 Design within funding...
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48 CFR 36.609-1 - Design within funding limitations.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false Design within funding limitations. 36.609-1 Section 36.609-1 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 36.609-1 Design within funding...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-07-07
...) Protection, Limit Engine Torque Loads for Sudden Engine Stoppage, and Design Roll Maneuver Requirement AGENCY... design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. These design features include limit engine torque loads for sudden engine...
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The case-control design in veterinary sciences: A survey.
Cullen, Jonah N; Sargeant, Jan M; Makielski, Kelly M; O'Connor, Annette M
2016-11-01
The case-control study design is deceptively simple. However, many design considerations influence the estimated effect measure. An investigation of case-control studies in the human health literature suggested that some of these considerations are not described in reports of case-control studies. Our hypothesis was that the majority of veterinary studies labeled as case-controls would be incident density designs, and many would not interpret the effect measure obtained from those studies as the rate ratio rather than the odds ratio. Reference databases were searched for author-designated case-control studies. A survey of 100 randomly selected studies was conducted to examine the different design options described and estimated effect measures. Of the 100 author-identified case-control studies, 83 assessed an exposure-outcome association and, of those, only 54 (65.1%) sampled the study population based on an outcome and would thus be considered case-control designs. Twelve studies were incidence density designs but none used this terminology. Of the studies that reported an odds ratio as the effect measure, none reported on additional considerations that would have enabled a more interpretable result. This survey indicated many case-control-labeled studies were not case-control designs and among case-control studies, key design aspects were not often described. The absence of information about study design elements and underlying assumptions in case-control studies limits the ability to establish the effect measured by the study and the evidentiary value of the study might be underestimated. Copyright © 2016 Elsevier B.V. All rights reserved.
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Towards a general object-oriented software development methodology
NASA Technical Reports Server (NTRS)
Seidewitz, ED; Stark, Mike
1986-01-01
Object diagrams were used to design a 5000 statement team training exercise and to design the entire dynamics simulator. The object diagrams are also being used to design another 50,000 statement Ada system and a personal computer based system that will be written in Modula II. The design methodology evolves out of these experiences as well as the limitations of other methods that were studied. Object diagrams, abstraction analysis, and associated principles provide a unified framework which encompasses concepts from Yourdin, Booch, and Cherry. This general object-oriented approach handles high level system design, possibly with concurrency, through object-oriented decomposition down to a completely functional level. How object-oriented concepts can be used in other phases of the software life-cycle, such as specification and testing is being studied concurrently.
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Can emergency medicine research benefit from adaptive design clinical trials?
Flight, Laura; Julious, Steven A; Goodacre, Steve
2017-04-01
Adaptive design clinical trials use preplanned interim analyses to determine whether studies should be stopped or modified before recruitment is complete. Emergency medicine trials are well suited to these designs as many have a short time to primary outcome relative to the length of recruitment. We hypothesised that the majority of published emergency medicine trials have the potential to use a simple adaptive trial design. We reviewed clinical trials published in three emergency medicine journals between January 2003 and December 2013. We determined the proportion that used an adaptive design as well as the proportion that could have used a simple adaptive design based on the time to primary outcome and length of recruitment. Only 19 of 188 trials included in the review were considered to have used an adaptive trial design. A total of 154/165 trials that were fixed in design had the potential to use an adaptive design. Currently, there seems to be limited uptake in the use of adaptive trial designs in emergency medicine despite their potential benefits to save time and resources. Failing to take advantage of adaptive designs could be costly to patients and research. It is recommended that where practical and logistical considerations allow, adaptive designs should be used for all emergency medicine clinical trials. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
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Patient engagement and the design of digital health
Birnbaum, Faith; Lewis, Dana M.; Rosen, Rochelle; Ranney, Megan L.
2015-01-01
Digital health is an area of growing interest for physicians, patients, and technology companies alike. It promises the ability to engage patients in their care, before, during, and after an emergency department visit. Current efforts to create, study, and disseminate digital health have been limited by lack of user engagement. In this commentary, we outline the imperative for engaging end-users in each phase of digital health design, as well as a few techniques to facilitate better digital health design and implementation. PMID:25997375
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Human Factors Engineering and Ergonomics in Systems Engineering
NASA Technical Reports Server (NTRS)
Whitmore, Mihriban
2017-01-01
The study, discovery, and application of information about human abilities, human limitations, and other human characteristics to the design of tools, devices, machines, systems, job tasks and environments for effective human performance.
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NASA Astrophysics Data System (ADS)
Jiao, Yi; Duan, Zhe
2017-01-01
In a diffraction-limited storage ring, half integer resonances can have strong effects on the beam dynamics, associated with the large detuning terms from the strong focusing and strong sextupoles as required for an ultralow emittance. In this study, the limitation of half integer resonances on the available momentum acceptance (MA) was statistically analyzed based on one design of the High Energy Photon Source (HEPS). It was found that the probability of MA reduction due to crossing of half integer resonances is closely correlated with the level of beta beats at the nominal tunes, but independent of the error sources. The analysis indicated that for the presented HEPS lattice design, the rms amplitude of beta beats should be kept below 1.5% horizontally and 2.5% vertically to reach a small MA reduction probability of about 1%.
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NASA Astrophysics Data System (ADS)
Bellier, Quentin; Bouit, Pierre-Antoine; Kamada, Kenji; Feneyrou, Patrick; Malmström, E.; Maury, Olivier; Andraud, Chantal
2009-09-01
The rapid development of frequency-tunable pulsed lasers up to telecommunication wavelengths (1400-1600 nm) led to the design of new materials for nonlinear absorption in this spectral range. In this context, two families of near infra-red (NIR) chromophores, namely heptamethine cyanine and aza-borondipyrromethene (aza-bodipy) dyes were studied. In both cases, they show significant two-photon absorption (TPA) cross-sections in the 1400-1600 nm spectral range and display good optical power limiting (OPL) properties. OPL curves were interpreted on the basis of TPA followed by excited state absorption (ESA) phenomena. Finally these systems have several relevant properties like nonlinear absorption properties, gram scale synthesis and high solubility. In addition, they could be functionalized on several sites which open the way to numerous practical applications in biology, solid-state optical limiting and signal processing.
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Guo, Wenbin; Liu, Feng; Chen, Jindong; Wu, Renrong; Li, Lehua; Zhang, Zhikun; Chen, Huafu; Zhao, Jingping
2017-03-01
Abnormal regional activity and functional connectivity of the default-mode network (DMN) have been reported in schizophrenia. However, previous studies may have been biased by unmatched case-control design. To limit such bias, the present study used both the family-based case-control design and the traditional case-control design to investigate abnormal regional activity of the DMN in patients with schizophrenia at rest.Twenty-eight first-episode, drug-naive patients with schizophrenia, 28 age-, sex-matched unaffected siblings of the patients (family-based controls, FBC), and 40 healthy controls (HC) underwent resting-state functional magnetic resonance imaging (fMRI) scans. The group-independent component analysis and fractional amplitude of low-frequency fluctuation (fALFF) methods were used to analyze the data.Patients with schizophrenia show increased fALFF in an overlapped region of the right superior medial prefrontal cortex (MPFC) relative to the FBC and the HC. Compared with the HC, the patients and the FBC exhibit increased fALFF in an overlapped region of the left posterior cingulate cortex/precuneus (PCC/PCu). Furthermore, the z values of the 2 overlapped regions can separate the patients from the FBC/HC, and separate the patients/FBC from the HC with relatively high sensitivity and specificity.Both the family-based case-control and traditional case-control designs reveal hyperactivity of the DMN in first-episode, drug-naive patients with paranoid schizophrenia, which highlights the importance of the DMN in the neurobiology of schizophrenia. Family-based case-control design can limit the confounding effects of environmental factors in schizophrenia. Combination of the family-based case-control and traditional case-control designs may be a viable option for the neuroimaging studies.
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Fabrizio, Cecilia S; van Liere, Marti; Pelto, Gretel
2014-01-01
As stunting moves to the forefront of the global agenda, there is substantial evidence that behaviour change interventions (BCI) can improve infant feeding practices and growth. However, this evidence has not been translated into improved outcomes on a national level because we do not know enough about what makes these interventions work, for whom, when, why, at what cost and for how long. Our objective was to examine the design and implementation of complementary feeding BCI, from the peer-reviewed literature, to identify generalisable key determinants. We identified 29 studies that evaluated BCI efficacy or effectiveness, were conducted in developing countries, and reported outcomes on infant and young children aged 6–24 months. Two potential determinants emerged: (1) effective studies used formative research to identify cultural barriers and enablers to optimal feeding practices, to shape the intervention strategy, and to formulate appropriate messages and mediums for delivery; (2) effective studies delineated the programme impact pathway to the target behaviour change and assessed intermediary behaviour changes to learn what worked. We found that BCI that used these developmental and implementation processes could be effective despite heterogeneous approaches and design components. Our analysis was constrained, however, by the limited published data on how design and implementation were carried out, perhaps because of publishing space limits. Information on cost-effectiveness, sustainability and scalability was also very limited. We suggest a more comprehensive reporting process and a more strategic research agenda to enable generalisable evidence to accumulate. PMID:24798264
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From randomized controlled trials to observational studies.
Silverman, Stuart L
2009-02-01
Randomized controlled trials are considered the gold standard in the hierarchy of research designs for evaluating the efficacy and safety of a treatment intervention. However, their results can have limited applicability to patients in clinical settings. Observational studies using large health care databases can complement findings from randomized controlled trials by assessing treatment effectiveness in patients encountered in day-to-day clinical practice. Results from these designs can expand upon outcomes of randomized controlled trials because of the use of larger and more diverse patient populations with common comorbidities and longer follow-up periods. Furthermore, well-designed observational studies can identify clinically important differences among therapeutic options and provide data on long-term drug effectiveness and safety.
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Szerkus, O; Jacyna, J; Wiczling, P; Gibas, A; Sieczkowski, M; Siluk, D; Matuszewski, M; Kaliszan, R; Markuszewski, M J
2016-09-01
Fluoroquinolones are considered as gold standard for the prevention of bacterial infections after transrectal ultrasound guided prostate biopsy. However, recent studies reported that fluoroquinolone- resistant bacterial strains are responsible for gradually increasing number of infections after transrectal prostate biopsy. In daily clinical practice, antibacterial efficacy is evaluated only in vitro, by measuring the reaction of bacteria with an antimicrobial agent in culture media (i.e. calculation of minimal inhibitory concentration). Such approach, however, has no relation to the treated tissue characteristics and might be highly misleading. Thus, the objective of this study was to develop, with the use of Design of Experiments approach, a reliable, specific and sensitive ultra-high performance liquid chromatography- diode array detection method for the quantitative analysis of levofloxacin in plasma and prostate tissue samples obtained from patients undergoing prostate biopsy. Moreover, correlation study between concentrations observed in plasma samples vs prostatic tissue samples was performed, resulting in better understanding, evaluation and optimization of the fluoroquinolone-based antimicrobial prophylaxis during transrectal ultrasound guided prostate biopsy. Box-Behnken design was employed to optimize chromatographic conditions of the isocratic elution program in order to obtain desirable retention time, peak symmetry and resolution of levofloxacine and ciprofloxacine (internal standard) peaks. Fractional Factorial design 2(4-1) with four center points was used for screening of significant factors affecting levofloxacin extraction from the prostatic tissue. Due to the limited number of tissue samples the prostatic sample preparation procedure was further optimized using Central Composite design. Design of Experiments approach was also utilized for evaluation of parameter robustness. The method was found linear over the range of 0.030-10μg/mL for human plasma and 0.300-30μg/g for human prostate tissue samples. The intra-day and inter-day variability for levofloxacine from both plasma and prostate samples were less than 10%, with accuracies between 93 and 108% of the nominal values. The limit of detection and the limit of quantification for human plasma were 0.01μg/mL and 0.03μg/mL, respectively. For the prostate tissue, the limit of detection and the limit of quantification were 0.1μg/g and 0.3μg/g, respectively. The average recoveries of levofloxacin were in the range from 99 to 106%. Also, the method fulfills requirements of robustness what was determined and proved by Design of Experiments. The developed method was successfully applied to examine prostate tissue and plasma samples from 140 hospitalized patients enrolled into the clinical study, 12h after oral administration of LVF at a dose of 500mg. The mean (±SD) LVF concentration in prostate was 6.22±3.52μg/g and in plasma 2.54±1.14μg/mL. Due to simplicity of the method and relative small amount of sample needed for the assay, the method can be applied in clinical practice for monitoring of LVF concentrations in plasma and prostate gland. Copyright © 2016 Elsevier B.V. All rights reserved.
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Mhaskar, Rahul; Pathak, Elizabeth Barnett; Wieten, Sarah; Guterbock, Thomas M; Kumar, Ambuj; Djulbegovic, Benjamin
2015-08-01
Institutional Review Board (IRB) members have a duty to protect the integrity of the research process, but little is known about their basic knowledge of clinical research study designs. A nationwide sample of IRB members from major US research universities completed a web-based questionnaire consisting of 11 questions focusing on basic knowledge about clinical research study designs. It included questions about randomized controlled trials (RCTs) and other observational research study designs. Potential predictors (age, gender, educational attainment, type of IRB, current IRB membership, years of IRB service, clinical research experience, and self-identification as a scientist) of incorrect answers were evaluated using multivariate logistic regression models. 148 individuals from 36 universities participated. The majority of participants, 68.9% (102/148), were holding a medical or doctoral degree. Overall, only 26.5% (39/148) of participants achieved a perfect score of 11. On the six-question subset addressing RCTs, 46.6% (69/148) had a perfect score. Most individual questions, and the summary model of overall quiz score (perfect vs. not perfect), revealed no significant predictors - indicating that knowledge deficits were not limited to specific subgroups of IRB members. For the RCT knowledge score there was one significant predictor: compared with MDs, IRB members without a doctoral degree were three times as likely to answer at least one RCT question incorrectly (Odds Ratio: 3.00, 95% CI 1.10-8.20). However, even among MD IRB members, 34.1% (14/41) did not achieve a perfect score on the six RCT questions. This first nationwide study of IRB member knowledge about clinical research study designs found significant knowledge deficits. Knowledge deficits were not limited to laypersons or community advocate members of IRBs, as previously suggested. Akin to widespread ethical training requirements for clinical researchers, IRB members should undergo systematic training on clinical research designs.
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Time delay compensation for closed-loop insulin delivery systems: a simulation study.
Reboldi, G P; Home, P D; Calabrese, G; Fabietti, P G; Brunetti, P; Massi Benedetti, M
1991-06-01
Closed loop insulin therapy certainly represents the best possible approach to insulin replacement. However, present limitations preclude wider application of the so-called artificial pancreas. Therefore, a thorough understanding of these limitations is needed to design better systems for future long-term use. The present simulation study was design: to obtain better information on the impact of the measurement delay of currently available closed-loop devices both during closed-loop insulin delivery and blood glucose clamp studies, and to design and test a time delay compensator based on the method originally described by O.J. Smith. Simulations were performed on a Compaq Deskpro 486/25 personal computer under MS-DOS operating system using Simnon rel. 3.00 software. There was a direct relationship between measurement delay and amount of insulin delivered, i.e., the longer the delay the higher the insulin dose needed to control a rise in blood glucose; the closed-loop response in presence of a time delay was qualitatively impaired both during insulin delivery and blood glucose clamp studies; time delay compensation was effective in reducing the insulin dose and improving controller stability during the early phase of clamp studies. However, the robustness of a Smith's predictor-based controller should be carefully evaluated before implementation in closed-loop systems can be considered.
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Methodological Considerations in Designing and Evaluating Animal-Assisted Interventions.
Stern, Cindy; Chur-Hansen, Anna
2013-02-27
This paper presents a discussion of the literature on animal-assisted interventions and describes limitations surrounding current methodological quality. Benefits to human physical, psychological and social health cannot be empirically confirmed due to the methodological limitations of the existing body of research, and comparisons cannot validly be made across different studies. Without a solid research base animal-assisted interventions will not receive recognition and acceptance as a credible alternative health care treatment. The paper draws on the work of four systematic reviews conducted over April-May 2009, with no date restrictions, focusing exclusively on the use of canine-assisted interventions for older people residing in long-term care. The reviews revealed a lack of good quality studies. Although the literature base has grown in volume since its inception, it predominantly consists of anecdotal accounts and reports. Experimental studies undertaken are often flawed in aspects of design, conduct and reporting. There are few qualitative studies available leading to the inability to draw definitive conclusions. It is clear that due to the complexities associated with these interventions not all weaknesses can be eliminated. However, there are basic methodological weaknesses that can be addressed in future studies in the area. Checklists for quantitative and qualitative research designs to guide future research are offered to help address methodological rigour.
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49 CFR 192.201 - Required capacity of pressure relieving and limiting stations.
Code of Federal Regulations, 2010 CFR
2010-10-01
... Design of Pipeline Components § 192.201 Required capacity of pressure relieving and limiting stations. (a) Each pressure relief station or pressure limiting station or group of those stations installed to... part of the pipeline or distribution system in excess of those for which it was designed, or against...
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NASA Astrophysics Data System (ADS)
1981-04-01
Overriding considerations, including type of hoist, capacity limitations, operating speed, haulage ropes, guides, conveyance, and landings were studied within the context both of feasibility and of minimizing equipment costs. The study led to the selection of a twin drum, twin electric drive hoist, and for depths as much as 5000 ft, hoist capacities of up to 300 tons were found to be feasible. A brief reference is made to the requirements for hoisting equipment other than for heavy loads.
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NASA Technical Reports Server (NTRS)
Bentley, Nicole L.; Brower, David V.; Le, Suy Q.; Seaman, Calvin H.; Tang, Henry H.
2017-01-01
This paper presents the design and development of a friction-based coupling device for a fiber-optic monitoring system that can be deployed on existing subsea structures. This paper provides a summary of the design concept, prototype development, prototype performance testing, and design refinements of the device. The results of the laboratory testing of the first prototype performed at the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) are included in this paper. Limitations of the initial design were identified and future design improvements were proposed. These new features will enhance the coupling of the device and improve the monitoring system measurement capabilities. A major challenge of a post-installed instrumentation monitoring system is to ensure adequate coupling between the instruments and the structure of interest for reliable measurements. Friction-based coupling devices have the potential to overcome coupling limitations caused by marine growth and soil contamination on subsea structures, flowlines or risers. The work described in this paper investigates the design of a friction-based coupling device (friction clamp), which is applicable for pipelines and structures that are suspended in the water column and those that are resting on the seabed. The monitoring elements consist of fiber-optic sensors that are bonded to a metal clamshell with a high-friction coating. The friction clamp has a single hinge design to facilitate the operation of the clamp and dual rows of opposing fasteners to distribute the clamping force on the structure. The friction clamp can be installed by divers in shallow depths or by remotely operated vehicles in deep-water applications. NASA-JSC was involved in the selection and testing of the friction coating, and in the design and testing of the prototype clamp device. Four-inch diameter and eight-inch diameter sub-scale friction clamp prototypes were built and tested to evaluate the strain measuring capabilities of the design under different loading scenarios. The testing revealed some limitations of the initial design concept, and subsequent refinements were explored to improve the measurement performance of the system. This study was part of a collaboration between NASA-JSC and Astro Technology, Inc. within a study called Clear Gulf. The primary objective of the Clear Gulf study is to develop advanced instrumentation technologies that will improve operational safety and reduce the risk of hydrocarbon spillage. NASA provided unique insights, expansive test facilities, and technical expertise to advance these technologies that would benefit the environment, the public, and commercial industries.
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NASA Technical Reports Server (NTRS)
Bentley, Nicole; Brower, David; Le, Suy Q.; Seaman, Calvin; Tang, Henry
2017-01-01
This paper presents the design and development of a friction-based coupling device for a fiber-optic monitoring system that can be deployed on existing subsea structures. This paper provides a summary of the design concept, prototype development, prototype performance testing, and design refinements of the device. The results of the laboratory testing of the first prototype performed at the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) are included in this paper. Limitations of the initial design were identified and future design improvements were proposed. These new features will enhance the coupling of the device and improve the monitoring system measurement capabilities. A major challenge of a post-installed instrumentation monitoring system is to ensure adequate coupling between the instruments and the structure of interest for reliable measurements. Friction-based coupling devices have the potential to overcome coupling limitations caused by marine growth and soil contamination on subsea structures, flowlines or risers. The work described in this paper investigates the design of a friction-based coupling device (friction clamp), which is applicable for pipelines and structures that are suspended in the water column and those that are resting on the seabed. The monitoring elements consist of fiber-optic sensors that are bonded to a metal clamshell with a high-friction coating. The friction clamp has a single hinge design to facilitate the operation of the clamp and dual rows of opposing fasteners to distribute the clamping force on the structure. The friction clamp can be installed by divers in shallow depths or by remotely operated vehicles in deep-water applications. NASA-JSC was involved in the selection and testing of the friction coating, and in the design and testing of the prototype clamp device. Four-inch diameter and eight-inch diameter sub-scale friction clamp prototypes were built and tested to evaluate the strain measuring capabilities of the design under different loading scenarios. The testing revealed some limitations of the initial design concept, and subsequent refinements were explored to improve the measurement performance of the system. This study was part of a collaboration between NASA-JSC and Astro Technology, Inc. within a study called Clear Gulf. The primary objective of the Clear Gulf study is to develop advanced instrumentation technologies that will improve operational safety and reduce the risk of hydrocarbon spillage. NASA provided unique insights, expansive test facilities, and technical expertise to advance these technologies that would benefit the environment, the public, and commercial industries.
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Anaby, Dana; Lal, Shalini; Huszczynski, Justine; Maich, Jana; Rogers, Jade; Law, Mary
2014-11-01
Comparative effectiveness research (CER) strives for evidence to inform clinical decisions for specific clients in typical health care settings. While the randomized controlled trial (RCT) is well-aligned with the objectives of CER, this design may not be feasible or applicable to all research questions, particularly those pertaining to clinical decision making and individually based change. It is important, therefore, to consider alternative approaches, especially when studying complex and subjective outcomes such as children's participation. We propose the use of interrupted time series (ITS) quasi-experimental design for its potential application in determining the effectiveness of participation-focused interventions. In this perspective, ITS design is described, ascertaining its advantages and limitations, and suggestions are provided to overcome challenges to implementation. Results of a case study using the ITS approach to evaluate changes in participation of an adolescent with physical disabilities are described. Finally, strategies to implement this design in practice are suggested.
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Safeguards Approaches for Black Box Processes or Facilities
DOE Office of Scientific and Technical Information (OSTI.GOV)
Diaz-Marcano, Helly; Gitau, Ernest TN; Hockert, John
2013-09-25
The objective of this study is to determine whether a safeguards approach can be developed for “black box” processes or facilities. These are facilities where a State or operator may limit IAEA access to specific processes or portions of a facility; in other cases, the IAEA may be prohibited access to the entire facility. The determination of whether a black box process or facility is safeguardable is dependent upon the details of the process type, design, and layout; the specific limitations on inspector access; and the restrictions placed upon the design information that can be provided to the IAEA. Thismore » analysis identified the necessary conditions for safeguardability of black box processes and facilities.« less
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Design of an occulter testbed at flight Fresnel numbers
NASA Astrophysics Data System (ADS)
Sirbu, Dan; Kasdin, N. Jeremy; Kim, Yunjong; Vanderbei, Robert J.
2015-01-01
An external occulter is a spacecraft flown along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. Laboratory verification of occulter designs is necessary to validate the optical models used to design and predict occulter performance. At Princeton, we are designing and building a testbed that allows verification of scaled occulter designs whose suppressed shadow is mathematically identical to that of space occulters. Here, we present a sample design operating at a flight Fresnel number and is thus representative of a realistic space mission. We present calculations of experimental limits arising from the finite size and propagation distance available in the testbed, limitations due to manufacturing feature size, and non-ideal input beam. We demonstrate how the testbed is designed to be feature-size limited, and provide an estimation of the expected performance.
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Educational Robotics as Mindtools
ERIC Educational Resources Information Center
Mikropoulos, Tassos A.; Bellou, Ioanna
2013-01-01
Although there are many studies on the constructionist use of educational robotics, they have certain limitations. Some of them refer to robotics education, rather than educational robotics. Others follow a constructionist approach, but give emphasis only to design skills, creativity and collaboration. Some studies use robotics as an educational…
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ERIC Educational Resources Information Center
Ziller, Erika C.; Coburn, Andrew F.; Anderson, Nathaniel J.; Loux, Stephenie L.
2008-01-01
Context: Although research shows higher uninsured rates among rural versus urban individuals, prior studies are limited because they do not examine coverage across entire rural families. Purpose: This study uses the Medical Expenditure Panel Survey (MEPS) to compare rural and urban insurance coverage within families, to inform the design of…
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Limitations to the study of man in space in the U.S. space program
NASA Technical Reports Server (NTRS)
Bishop, Phillip A.; Greenisen, Mike
1993-01-01
Research on humans conducted during spaceflight is fraught both with great opportunities and great obstacles. The purpose of this paper is to review some of the limitations to research in space in the United States with hope that an informed scientific community may lead to more rapid and efficient solution of these problems. Limitations arise because opportunities to study the same astronauts in well-controlled situations on repeated spaceflights are practically non-existent. Human research opportunities are further limited by the necessity of avoiding simultaneous mutually-interfering experiments. Environmental factors, including diet and other physiological perturbations concomitant with spaceflight, also complicate research design and interpretation. Technical limitations to research methods and opportunities further restrict the development of the knowledge base. Finally, Earth analogues of space travel all suffer from inadequacies. Though all of these obstacles will eventually be overcome, creativity, diligence, and persistence are required to further our knowledge of humans in space.
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Limitations to the study of man in the United States space program
NASA Technical Reports Server (NTRS)
Bishop, Phillip A.; Greenisen, Mike
1992-01-01
Research on humans conducted during space flight is fraught both with great opportunities and great obstacles. The purpose of this paper is to review some of the limitations to United States research in space in the hope that an informed scientific community may lead to more rapid and efficient solution of these problems. Limitations arise because opportunities to study the same astronauts in well-controlled situations on repeated space flights are practically non-existent. Human research opportunities are further limited by the necessity of avoiding simultaneous mutually-interfereing experiments. Environmental factors including diet and other physiological perturbations concomitant with space flight also complicates research design and interpretation. Technical limitations to research methods and opportunities further restrict the development of the knowledge base. Finally, earth analogues of space travel all suffer from inadequacies. Though all of these obstacles will eventually be overcome; creativity, diligence, and persistence are required to further our knowledge of humans in space.
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Limitations to the study of man in space in the U.S. space program.
Bishop, P A; Greenisen, M
1993-03-01
Research on humans conducted during spaceflight is fraught both with great opportunities and great obstacles. The purpose of this paper is to review some of the limitations to research in space in the United States with hope that an informed scientific community may lead to more rapid and efficient solution of these problems. Limitations arise because opportunities to study the same astronauts in well-controlled situations on repeated spaceflights are practically non-existent. Human research opportunities are further limited by the necessity of avoiding simultaneous mutually-interfering experiments. Environmental factors, including diet and other physiological perturbations concomitant with spaceflight, also complicate research design and interpretation. Technical limitations to research methods and opportunities further restrict the development of the knowledge base. Finally, Earth analogues of space travel all suffer from inadequacies. Though all of these obstacles will eventually be overcome, creativity, diligence, and persistence are required to further our knowledge of humans in space.
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Revised Point of Departure Design Options for Nuclear Thermal Propulsion
NASA Technical Reports Server (NTRS)
Fittje, James E.; Schnitzler, Bruce G.; Borowoski, Stanley
2015-01-01
Four Revised Point of Departure NTR Engines were Designed and Analyzed using MCNP and NESS. All Four Engines Have Thermodynamically Closed Cycles at Nominal Chamber Pressures. 111 kilonewton (25 kip-force) Cermet Design Required Dedicated Heater Elements to Close the Cycle. Cermet Based Designs had Slightly Higher TW Ratios, but Required Substantially More U-235. NERVA Derived Criticality Limited Engine Could Operate at Lower Power and Thrust Levels Compared to the Criticality Limited Cermet Design.
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NASA Astrophysics Data System (ADS)
Mbagwu, Chukwuka Chijindu
High speed, air-breathing hypersonic vehicles encounter a varied range of engine and operating conditions traveling along cruise/ascent missions at high altitudes and dynamic pressures. Variations of ambient pressure, temperature, Mach number, and dynamic pressure can affect the combustion conditions in conflicting ways. Computations were performed to understand propulsion tradeoffs that occur when a hypersonic vehicle travels along an ascent trajectory. Proper Orthogonal Decomposition methods were applied for the reduction of flamelet chemistry data in an improved combustor model. Two operability limits are set by requirements that combustion efficiency exceed selected minima and flameout be avoided. A method for flameout prediction based on empirical Damkohler number measurements is presented. Operability limits are plotted that define allowable flight corridors on an altitude versus flight Mach number performance map; fixed-acceleration ascent trajectories were considered for this study. Several design rules are also presented for a hypersonic waverider with a dual-mode scramjet engine. Focus is placed on ''vehicle integration" design, differing from previous ''propulsion-oriented" design optimization. The well-designed waverider falls between that of an aircraft (high lift-to-drag ratio) and a rocket (high thrust-to-drag ratio). 84 variations of an X-43-like vehicle were run using the MASIV scramjet reduced order model to examine performance tradeoffs. Informed by the vehicle design study, variable-acceleration trajectory optimization was performed for three constant dynamic pressures ascents. Computed flameout operability limits were implemented as additional constraints to the optimization problem. The Michigan-AFRL Scramjet In-Vehicle (MASIV) waverider model includes finite-rate chemistry, applied scaling laws for 3-D turbulent mixing, ram-scram transition and an empirical value of the flameout Damkohler number. A reduced-order modeling approach is justified (in lieu of higher-fidelity computational simulations) because all vehicle forces are computed multiple thousands of times to generate multi-dimensional performance maps. The findings of this thesis work present a number of compelling conclusions. It is found that the ideal operating conditions of a scramjet engine are heavily dependent on the ambient and combustor pressure (and less strongly on temperature). Combustor pressures of approximately 1.0 bar or greater achieve the highest combustion efficiency, in line with industry standards of more than 0.5 bar. Ascent trajectory analysis of combustion efficiency and lean-limit flameout dictate best operation at higher dynamic pressures and lower altitudes, but these goals are traded off by current structural limitations whereby dynamic pressures must remain below 100 kPa. Hypersonic waverider designs varied between an "airplane" and a "rocket" are found to have better performance with the latter design, with controllability and minimum elevon/rudder surface area as a stability constraint for the vehicle trim. Ultimately, these findings are beneficial and contribute to the overall understanding of dynamically stable waverider vehicles at hypersonic speeds. These types of vehicles have a range of applications from technology demonstration, to earth-to-low orbit payload transit, to most compellingly another step in the development and realization of viable supersonic commercial transport.
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Bernie, Charmaine; Harvey, Adrienne R; McGinley, Jennifer L; Spittle, Alicia J
2017-01-01
Objectives The primary objective is to systematically evaluate the evidence for the effectiveness of task-specific training (TST) of gross motor skills for improving activity and/or participation outcomes in ambulant school-aged children with cerebral palsy (CP). The secondary objective is to identify motor learning strategies reported within TST and assess relationship to outcome. Design Systematic review. Method Relevant databases were searched for studies including: children with CP (mean age >4 years and >60% of the sample ambulant); TST targeting gross motor skills and activity (skill performance, gross motor function and functional skills) and/or participation-related outcomes. Quality of included studies was assessed using standardised tools for risk of bias, study design and quality of evidence across outcomes. Continuous data were summarised for each study using standardised mean difference (SMD) and 95% CIs. Results Thirteen studies met inclusion criteria: eight randomised controlled trials (RCTs), three comparative studies, one repeated-measures study and one single-subject design study. Risk of bias was moderate across studies. Components of TST varied and were often poorly reported. Within-group effects of TST were positive across all outcomes of interest in 11 studies. In RCTs, between-group effects were conflicting for skill performance and functional skills, positive for participation-related outcomes (one study: Life-HABITS performance SMD=1.19, 95% CI 0.3 to 2.07, p<0.001; Life-HABITS satisfaction SMD=1.29, 95% CI 0.40 to 2.18, p=0.001), while no difference or negative effects were found for gross motor function. The quality of evidence was low-to-moderate overall. Variability and poor reporting of motor learning strategies limited assessment of relationship to outcome. Conclusions Limited evidence for TST for gross motor skills in ambulant children with CP exists for improving activity and participation-related outcomes and recommendations for use over other interventions are limited by poor study methodology and heterogeneous interventions. Registration PROSPERO ID42016036727 PMID:29637118
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Conceptual design studies of the 5 m terahertz antenna for Dome A, Antarctica
NASA Astrophysics Data System (ADS)
Yang, Ji; Zuo, Ying-Xi; Lou, Zheng; Cheng, Jing-Quan; Zhang, Qi-Zhou; Shi, Sheng-Cai; Huang, Jia-Sheng; Yao, Qi-Jun; Wang, Zhong
2013-12-01
As the highest, coldest and driest place in Antarctica, Dome A provides exceptionally good observing conditions for ground-based observations over terahertz wavebands. The 5 m Dome A Terahertz Explorer (DATE5) has been proposed to explore new terahertz windows, primarily over wavelengths between 350 and 200 μm. DATE5 will be an open-air, fully-steerable telescope that can function by unmanned operation with remote control. The telescope will be able to endure the harsh polar environment, including high altitude, very low temperature and very low air pressure. The unique specifications, including high accuracies for surface shape and pointing and fully automatic year-around remote operation, along with a stringent limit on the periods of on-site assembly, testing and maintenance, bring a number of challenges to the design, construction, assembly and operation of this telescope. This paper introduces general concepts related to the design of the DATE5 antenna. Beginning from an overview of the environmental and operational limitations, the design specifications and requirements of the DATE5 antenna are listed. From these, major aspects on the conceptual design studies, including the antenna optics, the backup structure, the panels, the subreflector, the mounting and the antenna base structure, are explained. Some critical issues of performance are justified through analyses that use computational fluid dynamics, thermal analysis and de-icing studies, and the proposed approaches for test operation and on-site assembly. Based on these studies, we conclude that the specifications of the DATE5 antenna can generally be met by using enhanced technological approaches.
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Epidemiological designs for vaccine safety assessment: methods and pitfalls.
Andrews, Nick
2012-09-01
Three commonly used designs for vaccine safety assessment post licensure are cohort, case-control and self-controlled case series. These methods are often used with routine health databases and immunisation registries. This paper considers the issues that may arise when designing an epidemiological study, such as understanding the vaccine safety question, case definition and finding, limitations of data sources, uncontrolled confounding, and pitfalls that apply to the individual designs. The example of MMR and autism, where all three designs have been used, is presented to help consider these issues. Copyright © 2011 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.
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Study of an engine flow diverter system for a large scale ejector powered aircraft model
NASA Technical Reports Server (NTRS)
Springer, R. J.; Langley, B.; Plant, T.; Hunter, L.; Brock, O.
1981-01-01
Requirements were established for a conceptual design study to analyze and design an engine flow diverter system and to include accommodations for an ejector system in an existing 3/4 scale fighter model equipped with YJ-79 engines. Model constraints were identified and cost-effective limited modification was proposed to accept the ejectors, ducting and flow diverter valves. Complete system performance was calculated and a versatile computer program capable of analyzing any ejector system was developed.
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Power and sample size for multivariate logistic modeling of unmatched case-control studies.
Gail, Mitchell H; Haneuse, Sebastien
2017-01-01
Sample size calculations are needed to design and assess the feasibility of case-control studies. Although such calculations are readily available for simple case-control designs and univariate analyses, there is limited theory and software for multivariate unconditional logistic analysis of case-control data. Here we outline the theory needed to detect scalar exposure effects or scalar interactions while controlling for other covariates in logistic regression. Both analytical and simulation methods are presented, together with links to the corresponding software.
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2016-10-14
ABSTRACT DTAGs have proven to be a valuable tool for the study of marine mammal acoustics and fine scale motion. The success of the DTAG has resulted in...Underwater Acoustics , Digital Communications 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF a. REPORT b. ABSTRACT c. THIS PAGE ABSTRACT u u u...continuously monitor and improve the tag design.\\ OBJECTIVES Dtags have proven to be a valuable tool for the study of marine mammal acoustics and fine
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Matthews, M; Rathleff, M S; Claus, A; McPoil, T; Nee, R; Crossley, K; Vicenzino, B
2017-12-01
Patellofemoral pain (PFP) is a multifactorial and often persistent knee condition. One strategy to enhance patient outcomes is using clinically assessable patient characteristics to predict the outcome and match a specific treatment to an individual. A systematic review was conducted to determine which baseline patient characteristics were (1) associated with patient outcome (prognosis); or (2) modified patient outcome from a specific treatment (treatment effect modifiers). 6 electronic databases were searched (July 2016) for studies evaluating the association between those with PFP, their characteristics and outcome. All studies were appraised using the Epidemiological Appraisal Instrument. Studies that aimed to identify treatment effect modifiers underwent a checklist for methodological quality. The 24 included studies evaluated 180 participant characteristics. 12 studies investigated prognosis, and 12 studies investigated potential treatment effect modifiers. Important methodological limitations were identified. Some prognostic studies used a retrospective design. Studies aiming to identify treatment effect modifiers often analysed too many variables for the limiting sample size and typically failed to use a control or comparator treatment group. 16 factors were reported to be associated with a poor outcome, with longer duration of symptoms the most reported (>4 months). Preliminary evidence suggests increased midfoot mobility may predict those who have a successful outcome to foot orthoses. Current evidence can identify those with increased risk of a poor outcome, but methodological limitations make it difficult to predict the outcome after one specific treatment compared with another. Adequately designed randomised trials are needed to identify treatment effect modifiers. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
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Fitzpatrick, Cole D; Rakasi, Saritha; Knodler, Michael A
2017-01-01
Speed is one of the most important factors in traffic safety as higher speeds are linked to increased crash risk and higher injury severities. Nearly a third of fatal crashes in the United States are designated as "speeding-related", which is defined as either "the driver behavior of exceeding the posted speed limit or driving too fast for conditions." While many studies have utilized the speeding-related designation in safety analyses, no studies have examined the underlying accuracy of this designation. Herein, we investigate the speeding-related crash designation through the development of a series of logistic regression models that were derived from the established speeding-related crash typologies and validated using a blind review, by multiple researchers, of 604 crash narratives. The developed logistic regression model accurately identified crashes which were not originally designated as speeding-related but had crash narratives that suggested speeding as a causative factor. Only 53.4% of crashes designated as speeding-related contained narratives which described speeding as a causative factor. Further investigation of these crashes revealed that the driver contributing code (DCC) of "driving too fast for conditions" was being used in three separate situations. Additionally, this DCC was also incorrectly used when "exceeding the posted speed limit" would likely have been a more appropriate designation. Finally, it was determined that the responding officer only utilized one DCC in 82% of crashes not designated as speeding-related but contained a narrative indicating speed as a contributing causal factor. The use of logistic regression models based upon speeding-related crash typologies offers a promising method by which all possible speeding-related crashes could be identified. Published by Elsevier Ltd.
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Optimization of Designs for Nanotube-based Scanning Probes
NASA Technical Reports Server (NTRS)
Harik, V. M.; Gates, T. S.; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
Optimization of designs for nanotube-based scanning probes, which may be used for high-resolution characterization of nanostructured materials, is examined. Continuum models to analyze the nanotube deformations are proposed to help guide selection of the optimum probe. The limitations on the use of these models that must be accounted for before applying to any design problem are presented. These limitations stem from the underlying assumptions and the expected range of nanotube loading, end conditions, and geometry. Once the limitations are accounted for, the key model parameters along with the appropriate classification of nanotube structures may serve as a basis for the design optimization of nanotube-based probe tips.
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NASA Technical Reports Server (NTRS)
Zinnecker, Alicia M.; Csank, Jeffrey
2015-01-01
Designing a closed-loop controller for an engine requires balancing trade-offs between performance and operability of the system. One such trade-off is the relationship between the 95 percent response time and minimum high-pressure compressor (HPC) surge margin (SM) attained during acceleration from idle to takeoff power. Assuming a controller has been designed to meet some specification on response time and minimum HPC SM for a mid-life (nominal) engine, there is no guarantee that these limits will not be violated as the engine ages, particularly as it reaches the end of its life. A characterization for the uncertainty in this closed-loop system due to aging is proposed that defines elliptical boundaries to estimate worst-case performance levels for a given control design point. The results of this characterization can be used to identify limiting design points that bound the possible controller designs yielding transient results that do not exceed specified limits in response time or minimum HPC SM. This characterization involves performing Monte Carlo simulation of the closed-loop system with controller constructed for a set of trial design points and developing curve fits to describe the size and orientation of each ellipse; a binary search procedure is then employed that uses these fits to identify the limiting design point. The method is demonstrated through application to a generic turbofan engine model in closed-loop with a simplified controller; it is found that the limit for which each controller was designed was exceeded by less than 4.76 percent. Extension of the characterization to another trade-off, that between the maximum high-pressure turbine (HPT) entrance temperature and minimum HPC SM, showed even better results: the maximum HPT temperature was estimated within 0.76 percent. Because of the accuracy in this estimation, this suggests another limit that may be taken into consideration during design and analysis. It also demonstrates the extension of the characterization to other attributes that contribute to the performance or operability of the engine. Metrics are proposed that, together, provide information on the shape of the trade-off between response time and minimum HPC SM, and how much each varies throughout the life cycle, at the limiting design points. These metrics also facilitate comparison of the expected transient behavior for multiple engine models.
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NASA Technical Reports Server (NTRS)
Zinnecker, Alicia M.; Csank, Jeffrey T.
2015-01-01
Designing a closed-loop controller for an engine requires balancing trade-offs between performance and operability of the system. One such trade-off is the relationship between the 95% response time and minimum high-pressure compressor (HPC) surge margin (SM) attained during acceleration from idle to takeoff power. Assuming a controller has been designed to meet some specification on response time and minimum HPC SM for a mid-life (nominal) engine, there is no guarantee that these limits will not be violated as the engine ages, particularly as it reaches the end of its life. A characterization for the uncertainty in this closed-loop system due to aging is proposed that defines elliptical boundaries to estimate worst-case performance levels for a given control design point. The results of this characterization can be used to identify limiting design points that bound the possible con- troller designs yielding transient results that do not exceed specified limits in response time or minimum HPC SM. This characterization involves performing Monte Carlo simulation of the closed-loop system with controller constructed for a set of trial design points and developing curve fits to describe the size and orientation of each ellipse; a binary search procedure is then employed that uses these fits to identify the limiting design point. The method is demonstrated through application to a generic turbofan engine model in closed- loop with a simplified controller; it is found that the limit for which each controller was designed was exceeded by less than 4.76%. Extension of the characterization to another trade-off, that between the maximum high-pressure turbine (HPT) entrance temperature and minimum HPC SM, showed even better results: the maximum HPT temperature was estimated within 0.76%. Because of the accuracy in this estimation, this suggests another limit that may be taken into consideration during design and analysis. It also demonstrates the extension of the characterization to other attributes that contribute to the performance or operability of the engine. Metrics are proposed that, together, provide information on the shape of the trade-off between response time and minimum HPC SM, and how much each varies throughout the life cycle, at the limiting design points. These metrics also facilitate comparison of the expected transient behavior for multiple engine models.
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Wyman, Peter A; Henry, David; Knoblauch, Shannon; Brown, C Hendricks
2015-10-01
The dynamic wait-listed design (DWLD) and regression point displacement design (RPDD) address several challenges in evaluating group-based interventions when there is a limited number of groups. Both DWLD and RPDD utilize efficiencies that increase statistical power and can enhance balance between community needs and research priorities. The DWLD blocks on more time units than traditional wait-listed designs, thereby increasing the proportion of a study period during which intervention and control conditions can be compared, and can also improve logistics of implementing intervention across multiple sites and strengthen fidelity. We discuss DWLDs in the larger context of roll-out randomized designs and compare it with its cousin the Stepped Wedge design. The RPDD uses archival data on the population of settings from which intervention unit(s) are selected to create expected posttest scores for units receiving intervention, to which actual posttest scores are compared. High pretest-posttest correlations give the RPDD statistical power for assessing intervention impact even when one or a few settings receive intervention. RPDD works best when archival data are available over a number of years prior to and following intervention. If intervention units were not randomly selected, propensity scores can be used to control for non-random selection factors. Examples are provided of the DWLD and RPDD used to evaluate, respectively, suicide prevention training (QPR) in 32 schools and a violence prevention program (CeaseFire) in two Chicago police districts over a 10-year period. How DWLD and RPDD address common threats to internal and external validity, as well as their limitations, are discussed.
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Wyman, Peter A.; Brown, C. Hendricks
2015-01-01
The dynamic wait-listed design (DWLD) and regression point displacement design (RPDD) address several challenges in evaluating group-based interventions when there is a limited number of groups. Both DWLD and RPDD utilize efficiencies that increase statistical power and can enhance balance between community needs and research priorities. The DWLD blocks on more time units than traditional wait-listed designs, thereby increasing the proportion of a study period during which intervention and control conditions can be compared, and can also improve logistics of implementing intervention across multiple sites and strengthen fidelity. We discuss DWLDs in the larger context of roll-out randomized designs and compare it with its cousin the Stepped Wedge design. The RPDD uses archival data on the population of settings from which intervention unit(s) are selected to create expected posttest scores for units receiving intervention, to which actual posttest scores are compared. High pretest-posttest correlations give the RPDD statistical power for assessing intervention impact even when one or a few settings receive intervention. RPDD works best when archival data are available over a number of years prior to and following intervention. If intervention units were not randomly selected, propensity scores can be used to control for nonrandom selection factors. Examples are provided of the DWLD and RPDD used to evaluate, respectively, suicide prevention training (QPR) in 32 schools and a violence prevention program (CeaseFire) in 2 Chicago police districts over a 10-year period. How DWLD and RPDD address common threats to internal and external validity, as well as their limitations, are discussed. PMID:25481512
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NASA Astrophysics Data System (ADS)
Yim, S.-W.; Park, B.-C.; Jeong, Y.-T.; Kim, Y.-J.; Yang, S.-E.; Kim, W.-S.; Kim, H.-R.; Du, H.-I.
2013-01-01
A 22.9 kV class hybrid fault current limiter (FCL) developed by Korea Electric Power Corporation and LS Industrial Systems in 2006 operates using the line commutation mechanism and begins to limit the fault current after the first half-cycle. The first peak of the fault current is available for protective coordination in the power system. However, it also produces a large electromagnetic force and imposes a huge stress on power facilities such as the main transformer and gas-insulated switchgear. In this study, we improved the operational characteristics of the hybrid FCL in order to reduce the first peak of the fault current. While maintaining the structure of the hybrid FCL system, we developed a superconducting module that detects and limits the fault current during the first half-cycle. To maintain the protective coordination capacity, the hybrid FCL was designed to reduce the first peak value of the fault current by up to approximately 30%. The superconducting module was also designed to produce a minimum AC loss, generating a small, uniform magnetic field distribution during normal operation. Performance tests confirmed that when applied to the hybrid FCL, the superconducting module showed successful current limiting operation without any damage.
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Gimbal system configurations and line-of-sight control techniques for small UAV applications
NASA Astrophysics Data System (ADS)
Miller, Rick; Mooty, Greg; Hilkert, J. M.
2013-05-01
The proliferation of small Unmanned Air Vehicles (UAVs) in the past decade has been driven, in part, by the diverse applications that various industries have found for these platforms. Originally, these applications were predominately military in nature but now include law enforcement/security, environmental monitoring/remote sensing, agricultural surveying, movie making and others. Many of these require sensors/payloads such as cameras, laser pointers/ illuminators/rangefinders and other systems that must be pointed and/or stabilized and therefore require a precision miniature gimbal or other means to control their line-of-sight (LOS). Until now, these markets have been served by traditional/larger gimbals; however, the latest class of small UAVs demands much smaller gimbals while maintaining high-performance. The limited size and weight of these gimbaled devices result in design challenges unique to the small-gimbal design field. In the past five years, Ascendant Engineering Solutions has engaged in designing, analyzing and building several small-gimbal systems to meet these challenges and has undertaken a number of trade studies to investigate techniques to achieve optimal performance within the inherent limitations mentioned above. These have included investigating various gimbal configurations, feedback sensors such as gyros, IMUs and encoders, drive train configurations, control system techniques, packaging and interconnect, as well as technology such as fast-steering mirrors and image-stabilization algorithms. This paper summarizes the results of these trade studies, attempts to identify inherent trends and limitations in the various design approaches and techniques, and discusses some practical issues such as test and verification.
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48 CFR 52.236-22 - Design Within Funding Limitations.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 48 Federal Acquisition Regulations System 2 2014-10-01 2014-10-01 false Design Within Funding Limitations. 52.236-22 Section 52.236-22 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION (CONTINUED) CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses 52.236-22 Design Within Funding...
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ERIC Educational Resources Information Center
Hannan, Michael T.; Tuma, Nancy Brandon
This document is part of a series of chapters described in SO 011 759. Working from the premise that temporal analysis is indispensable for the study of change, the document examines major alternatives in research design of this nature. Five sections focus on the features, advantages, and limitations of temporal analysis. Four designs which…
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Autonomous Aerodynamic Control of Micro Air Vehicles
2009-10-19
Wind tunnel studies have also begun in which detailed aerodynamic quantification can be mad regarding MAV performance with flexible airframes...research. The design is similar to existing MAVs. The airframe has a conventional aircraft design to allow for easy determination of aerodynamic...exceeded in normal flight by conventional aircraft ; however, it is not uncommon for a MAV to surpass the limits due to its low inertia. While collecting
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ERIC Educational Resources Information Center
See, Lai-Chu; Huang, Yu-Hsun; Chang, Yi-Hu; Chiu, Yeo-Ju; Chen, Yi-Fen; Napper, Vicki S.
2010-01-01
This study examines the timing using computer-enriched instruction (CEI), before or after a traditional lecture to determine cross-over effect, period effect, and learning effect arising from sequencing of instruction. A 2 x 2 cross-over design was used with CEI to teach central limit theorem (CLT). Two sequences of graduate students in nursing…
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1981-09-18
of bern current to space-charge limited Langmuir current - Cathode surface current density S 2 a Cylindrical diode geometry function (tabulated in...design factor . t -13- " r =J... .. ::!, qm ! . ... ... - . , m- d nc- Cd (3) lsically, this equation arises from the recognition that the gap...S. Beam Current as a Fraction of the Limiting Langmuir Current (o/IL) Equation 5 in Table I is basically intended to provide a measure of the C
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Design research and the globalization of healthcare environments.
Shepley, Mardelle McCuskey; Song, Yilin
2014-01-01
Global healthcare practice has expanded in the past 20 years. At the same time the incorporation of research into the design process has gained prominence as a best practice among architects. The authors of this study investigated the status of design research in a variety of international settings. We intended to answer the question, "how pervasive is healthcare design research outside of the United States?" The authors reviewed the international literature on the design of healthcare facilities. More than 500 international studies and conference proceedings were incorporated in this literature review. A team of five research assistants searched multiple databases comparing approximately 16 keywords to geographic location. Some of those keywords included: evidence-based design, salutogenic design, design research, and healthcare environment. Additional articles were gathered by contacting prominent researchers and asking for their personal assessment of local health design research studies. While there are design researchers in most parts of the world, the majority of studies focus on the needs of populations in developed countries and generate guidelines that have significant cost and cultural implications that prohibit their implementation in developing countries. Additionally, the body of literature discussing the role of culture in healthcare environments is extremely limited. Design researchers must address the cultural implications of their studies. Additionally, we need to expand our research objectives to address healthcare design in countries that have not been previous considered. © 2014 Vendome Group, LLC.
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Vitas, Selin; Keplinger, Tobias; Reichholf, Nico; Figi, Renato; Cabane, Etienne
2018-05-09
In this study, the chemical modification of bulk beech wood is described along with its utilization as biosorbent for the remediation of copper from water. The material was prepared by esterification using anhydrides, and reaction conditions were optimized to propose a greener process, in particular by reducing the amount of solvent. This modification yields a lignocellulosic material whose native structure is preserved, with an increased amount of carboxylic groups (up to 3 mmol/g). We demonstrate that the material can remove up to 95% of copper from low concentration solutions (100- 500 ppm). The adsorption efficiency decreases with concentrated copper solutions, and we show that a limited number of -COOH groups participate in copper binding (ca. 0.1 Cu/-COOH). This result suggests a limited accessibility of -COOH groups in the wood scaffold. This was demonstrated by the characterization of -COOH and copper distributions inside wood. Raman and EDX imaging confirmed that most -COOH groups are located inside the wood cell walls, thereby limiting interactions with copper. According to this study, critical limitations of bulk wood as a biosorbent were identified, and the results will be used to improve the material and design an efficient wood filter for heavy metal remediation. Copyright © 2018 Elsevier B.V. All rights reserved.
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NASA Astrophysics Data System (ADS)
Kolstein, M.; Chmeissani, M.
2016-01-01
The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.
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Advancing Health Professions Education Research by Creating a Network of Networks.
Carney, Patricia A; Brandt, Barbara; Dekhtyar, Michael; Holmboe, Eric S
2018-02-27
Producing the best evidence to show educational outcomes, such as competency achievement and credentialing effectiveness, across the health professions education continuum will require large multisite research projects and longitudinal studies. Current limitations that must be overcome to reach this goal include the prevalence of single-institution study designs, assessments of a single curricular component, and cross-sectional study designs that provide only a snapshot in time of a program or initiative rather than a longitudinal perspective.One solution to overcoming these limitations is to develop a network of networks that collaborates, using longitudinal approaches, across health professions and regions of the United States. Currently, individual networks are advancing educational innovation toward understanding the effectiveness of educational and credentialing programs. Examples of such networks include: (1) the American Medical Association's Accelerating Change in Medical Education initiative, (2) the National Center for Interprofessional Practice and Education, and (3) the Accreditation Council for Graduate Medical Education's Accreditation System. In this Invited Commentary, the authors briefly profile these existing networks, identify their progress and the challenges they have encountered, and propose a vigorous way forward toward creating a national network of networks designed to determine the effectiveness of health professions education and credentialing.
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Wang, Ruixue; Soll, Lindsey; Dugan, Vivien; Runstadler, Jonathan; Happ, George; Slemons, Richard D; Taubenberger, Jeffery K
2008-05-25
This study presents an interconnected approach for circumventing two inherent limitations associated with studies defining the natural history of influenza A viruses in wild birds. The first limiting factor is the ability to maintain a cold chain from specimen collection to the laboratory when study sites are in more remote locations. The second limiting factor is the ability to identify all influenza A virus HA subtypes present in an original sample. We report a novel method for molecular subtyping of avian influenza A virus hemagglutinin genes using degenerate primers designed to amplify all known hemagglutinin subtypes. It was shown previously that templates larger than 200 bp were not consistently amplifiable from ethanol-fixed cloacal swabs. For this study, new primer sets were designed within these constraints. This method was used to perform subtyping RT-PCR on 191 influenza RNA-positive ethanol-fixed cloacal swabs obtained from 880 wild ducks in central Alaska in 2005. Seven different co-circulating hemagglutinin subtypes were identified in this study set, including H1, H3, H4, H5, H6, H8, and H12. In addition, 16% of original cloacal samples showed evidence of mixed infection, with samples yielding from two-to-five different hemagglutinin subtypes. This study further demonstrates the complex ecobiology of avian influenza A viruses in wild birds.
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Wang, Ruixue; Soll, Lindsey; Dugan, Vivien; Runstadler, Jonathan; Happ, George; Slemons, Richard D.; Taubenberger, Jeffery K.
2008-01-01
This study presents an interconnected approach for circumventing two inherent limitations associated with studies defining the natural history of influenza A viruses in wild birds. The first limiting factor is the ability to maintain a cold chain from specimen collection to the laboratory when study sites are in more remote locations. The second limiting factor is the ability to identify all influenza A virus HA subtypes present in an original sample. We report a novel method for molecular subtyping of avian influenza A virus hemagglutinin genes using degenerate primers designed to amplify all known hemagglutinin subtypes. It was shown previously that templates larger than 200 bp were not consistently amplifiable from ethanol-fixed cloacal swabs. For this study, new primer sets were designed within these constraints. This method was used to perform subtyping RT-PCR on 191 influenza RNA-positive ethanol-fixed cloacal swabs obtained from 880 wild ducks in central Alaska in 2005. Seven different co-circulating hemagglutinin subtypes were identified in this study set, including H1, H3, H4, H5, H6, H8, and H12. In addition, 16% of original cloacal samples showed evidence of mixed infection, with samples yielding from two-to-five different hemagglutinin subtypes. This study further demonstrates the complex ecobiology of avian influenza A viruses in wild birds. PMID:18308356
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50 CFR 660.130 - Trawl fishery-management measures.
Code of Federal Regulations, 2012 CFR
2012-10-01
... is a trip limit, size limit, scientific sorting designation, quota, harvest guideline, ACL or ACT or..., scientific sorting designation, quota, harvest guideline, ACL or ACT or OY applied.” The States of Washington...
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50 CFR 660.130 - Trawl fishery-management measures.
Code of Federal Regulations, 2011 CFR
2011-10-01
... limit, size limit, scientific sorting designation, quota, harvest guideline, ACL or ACT or OY, if the... designation, quota, harvest guideline, ACL or ACT or OY applied.” The States of Washington, Oregon, and...
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Dobscha, Steven K.; Clark, Michael E.; Morasco, Benjamin J.; Freeman, Michele; Campbell, Rose; Helfand, Mark
2010-01-01
Objective To review the literature addressing the assessment and management of pain in patients with polytraumatic injuries including traumatic brain injury (TBI) and blast-related headache, and to identify patient, clinician and systems factors associated with pain-related outcomes. Design Systematic review. Methods We conducted searches in MEDLINE of literature published from 1950 through July 2008. Due to a limited number of studies using controls or comparators, we included observational and rigorous qualitative studies. We systematically rated the quality of systematic reviews, cohort, and case-control design studies. Results One systematic review, 93 observational studies, and one qualitative research study met inclusion criteria. The literature search yielded no published studies that assessed measures of pain intensity or pain-related functional interference among patients with cognitive deficits due to TBI, that compared patients with blast-related headache with patients with other types of headache, or that assessed treatments for blast-related headache pain. Studies on the association between TBI severity and pain reported mixed findings. There was limited evidence that the following factors are associated with pain among TBI patients: severity, location, and multiplicity of injuries; insomnia; fatigue; depression; and post-traumatic stress disorder. Conclusions Very little evidence is currently available to guide pain assessment and treatment approaches in patients with polytrauma. Further research employing systematic observational as well as controlled intervention designs is clearly indicated. PMID:19818031
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Study of novel concepts of power transmission gears
NASA Technical Reports Server (NTRS)
Rivin, Eugene I.
1991-01-01
Two concepts in power transmission gear design are proposed which provide a potential for large noise reduction and for improving weight to payload ratio due to use of advanced fiber reinforced and ceramic materials. These concepts are briefly discussed. Since both concepts use ultrathin layered rubber-metal laminates for accommodating limited travel displacements, properties of the laminates, such as their compressive strength, compressive and shear moduli were studied. Extensive testing and computational analysis were performed on the first concept gears (laminate coated conformal gears). Design and testing of the second conceptual design (composite gear with separation of sliding and rolling motions) are specifically described.
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Dionyssopoulos, Alexander; Karalis, Thanassis; Panitsides, Eugenia A
2014-12-31
Recent research has evidenced that although investment in Continuing Medical Education (CME), both in terms of participation as well as financial resources allocated to it, has been steadily increasing to catch up with accelerating advances in health information and technology, effectiveness of CME is reported to be rather limited. Poor and disproportional returns can be attributed to failure of CME courses to address and stimulate an adult audience. The present study initially drew on research findings and adult learning theories, providing the basis for comprehending adult learning, while entailing practical implications on fostering effectiveness in the design and delivery of CME. On a second level, a qualitative study was conducted with the aim to elucidate parameters accounting for effectiveness in educational interventions. Qualitative data was retrieved through 12 in-depth interviews, conducted with a random sample of participants in the 26th European Workshop of Advanced Plastic Surgery (EWAPS). The data underwent a three level qualitative analysis, following the "grounded theory" methodology, comprising 'open coding', 'axial coding' and 'selective coding'. Findings from the EWAPS study come in line with relevant literature, entailing significant implications for the necessity to apply a more effective and efficient paradigm in the design and delivery of educational interventions, advocating for implementing learner-centered schemata in CME and benefiting from a model that draws on the learning environment and social aspects of learning. What emerged as a pivotal parameter in designing educational interventions is to focus on small group educational events which could provide a supportive friendly context, enhance motivation through learner-centered approaches and allow interaction, experimentation and critical reflection. It should be outlined however that further research is required as the present study is limited in scope, having dealt with a limited sample.
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Thermal design of composite materials high temperature attachments
NASA Technical Reports Server (NTRS)
1972-01-01
The thermal aspects of using filamentary composite materials as primary airframe structures on advanced atmospheric entry spacecraft such as the space shuttle vehicle were investigated to identify and evaluate potential design approaches for maintaining composite structures within allowable temperature limits at thermal protection system (TPS) attachments and/or penetrations. The investigation included: (1) definition of thermophysical data for composite material structures; (2) parametric characterization and identification of the influence of the aerodynamic heating and attachment design parameters on composite material temperatures; (3) conceptual design, evaluation, and detailed thermal analyses of temperature limiting design concepts; and (4) the development of experimental data for assessment of the thermal design methodologies and data used for evaluation of the temperature-limiting design concepts. Temperature suppression attachment concepts were examined for relative merit. The simple isolator was identified as the most weight-effective concept and was selected for detail design, thermal analysis, and testing. Tests were performed on TPS standoff attachments to boron/aluminum, boron/polyimide and graphite/epoxy composite structures.
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Crystal, S; Fleishman, J A; Hays, R D; Shapiro, M F; Bozzette, S A
2000-12-01
Functional limitations of persons living with HIV affect their care needs and ability to perform social roles such as employment. Earlier estimates are outdated, and nationally representative estimates of prevalence and distribution of these limitations have not previously been available. The objectives of this study were to characterize physical and role limitations experienced by adults in care for HIV disease in the United States and to analyze variations by demographic and health characteristics in a multivariate framework. Among 2,836 respondents in the HIV Cost and Services Utilization Survey, we assessed physical functioning with a 9-item scale designed to span a broad continuum of tasks and administered the 2-item ACTG SF-21 role functioning scale. Linearization methods were used to account for the multistage survey design. Limitation in complex roles-working at a job, working around the house, or going to school-was more prevalent than limitation in most specific physical tasks. Among physical tasks, limitation was more prevalent in energy-demanding activities such as climbing stairs (43%) or walking >1 block (26%) than in self-care tasks such as bathing and dressing (14%). Greater limitation was associated with older age, lower educational attainment, more advanced disease, and higher symptom burden. Protease inhibitor treatment was associated with somewhat less physical limitation but no difference in role limitation. Functional status varied widely, suggesting the need for flexible, individualized care system responses. Results identified subgroups whose needs warrant special attention. Symptom intensity, pain, and fatigue were strongly associated with limitation; improved management of these disease manifestations might improve physical and social functioning.
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NASA Astrophysics Data System (ADS)
Kumlu, Kadriye Burcu Yavuz; Tüdeş, Şule
2017-10-01
The sustainability agenda has maintained its importance since the days, when the production system took its capitalist form, as well as the population in the urban areas started to rise. Increasing number of both goods and the people have caused the degradation of the certain systems, which generate the urban areas. These systems could mainly be classified as social, environmental, physical and economical systems. Today, urban areas still have difficulty to protect those systems, due to the significant demand of the population. Therefore, studies related with the sustainable issues are significant in the sense of continuity of the urban systems. Therefore, in this paper, those studies in the context of the effects of physical decisions taken in the spatial planning process on urban sustainability, will be examined. The components of the physical decisions are limited to land use, density and design. Land use decisions will be examined in the context of mixed land use. On the other hand, decisions related with density will be analyzed in the sense of population density and floor area ratio (FAR). Besides, design decisions will be examined, by linking them with neighborhood design criteria. Additionally, the term of urban sustainability will only be limited to its social and environmental contexts in this study. Briefly stated, studies in the sustainable literature concerned with the effects of land use, density and design decisions taken in the spatial planning process on the social and environmental sustainability will be examined in this paper. After the compilation and the analyze of those studies, a theoretical approach will be proposed to determine social and environmental sustainability in the context of land use, density and design decisions, taken in the spatial planning process.
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Li, Y; Chappell, A; Nyamdavaa, B; Yu, H; Davaasuren, D; Zoljargal, K
2015-03-01
The (137)Cs technique for estimating net time-integrated soil redistribution is valuable for understanding the factors controlling soil redistribution by all processes. The literature on this technique is dominated by studies of individual fields and describes its typically time-consuming nature. We contend that the community making these studies has inappropriately assumed that many (137)Cs measurements are required and hence estimates of net soil redistribution can only be made at the field scale. Here, we support future studies of (137)Cs-derived net soil redistribution to apply their often limited resources across scales of variation (field, catchment, region etc.) without compromising the quality of the estimates at any scale. We describe a hybrid, design-based and model-based, stratified random sampling design with composites to estimate the sampling variance and a cost model for fieldwork and laboratory measurements. Geostatistical mapping of net (1954-2012) soil redistribution as a case study on the Chinese Loess Plateau is compared with estimates for several other sampling designs popular in the literature. We demonstrate the cost-effectiveness of the hybrid design for spatial estimation of net soil redistribution. To demonstrate the limitations of current sampling approaches to cut across scales of variation, we extrapolate our estimate of net soil redistribution across the region, show that for the same resources, estimates from many fields could have been provided and would elucidate the cause of differences within and between regional estimates. We recommend that future studies evaluate carefully the sampling design to consider the opportunity to investigate (137)Cs-derived net soil redistribution across scales of variation. Copyright © 2014 Elsevier Ltd. All rights reserved.
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DOT National Transportation Integrated Search
1981-02-01
This volume documents the results of an analysis of the impact that various truck size and weight limits have on the carrier equipment selection process as a result of changes, in the design payload and design density of individual trucks. An analysi...
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Structural and functional connectivity as a driver of hillslope erosion following disturbance
USDA-ARS?s Scientific Manuscript database
Hydrologic response to rainfall input on fragmented or burnt hillslopes is strongly influenced by the ensuing connectivity of runoff and erosion processes. Yet, cross-scale process connectivity is seldom evaluated in field studies due scale limitations in experimental design. This study quantified...
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Radiation Protection for Lunar Mission Scenarios
NASA Technical Reports Server (NTRS)
Clowdsley, Martha S.; Nealy, John E.; Wilson, John W.; Anderson, Brooke M.; Anderson, Mark S.; Krizan, Shawn A.
2005-01-01
Preliminary analyses of shielding requirements to protect astronauts from the harmful effects of radiation on both short-term and long-term lunar missions have been performed. Shielding needs for both solar particle events (SPEs) and galactic cosmic ray (GCR) exposure are discussed for transit vehicles and surface habitats. This work was performed under the aegis of two NASA initiatives. The first study was an architecture trade study led by Langley Research Center (LaRC) in which a broad range of vehicle types and mission scenarios were compared. The radiation analysis for this study primarily focused on the additional shielding mass required to protect astronauts from the rare occurrence of a large SPE. The second study, led by Johnson Space Center (JSC), involved the design of lunar habitats. Researchers at LaRC were asked to evaluate the changes to mission architecture that would be needed if the surface stay were lengthened from a shorter mission duration of 30 to 90 days to a longer stay of 500 days. Here, the primary radiation concern was GCR exposure. The methods used for these studies as well as the resulting shielding recommendations are discussed. Recommendations are also made for more detailed analyses to minimize shielding mass, once preliminary vehicle and habitat designs have been completed. Here, methodologies are mapped out and available radiation analysis tools are described. Since, as yet, no dosimetric limits have been adopted for missions beyond low earth orbit (LEO), radiation exposures are compared to LEO limits. Uncertainties associated with the LEO career effective dose limits and the effects of lowering these limits on shielding mass are also discussed.
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Apovian, C M; Singer, M R; Campbell, W W; Bhasin, S; McCarthy, A C; Shah, M; Basaria, S; Moore, L L
2017-01-01
Nutrition impacts the development of sarcopenia and protein intake is an important modulator of skeletal muscle mass loss in older people. The Optimizing Protein Intake in Older Men with Mobility Limitation (OPTIMEN) Trial was designed to assess the independent and combined effects of higher protein intake and a promyogenic agent, testosterone, on lean body mass, muscle strength and physical function in older men with mobility disability. The purpose of this paper is to describe the experimental design and nutrition intervention, including techniques used by research dietitians to develop and deliver energy and protein-specific meals to the homes of community-dwelling participants. Strategies to enhance long-term dietary compliance are detailed. Randomized, double-blind, placebo-controlled six-month intervention trial. Participants were recruited from Boston MA USA and surrounding communities. Older men who were mobility-limited (Short Physical Performance Battery (SPPB) 3-10) and consuming less protein (<0.83 g/kg/day) were recruited for this study. Here we report the successful implementation of a double-blind, placebo-controlled, parallel group, randomized controlled trial with a 6-month intervention period among community-living men, age 65 years and older with a mobility limitation. A controlled feeding plan was used to deliver required energy intakes and prescribed protein quantities of 0.8 or 1.3 grams/kilogram/day (g/kg/d) in three meals plus snacks and supplements. A 2x2 factorial design was used to assess the effects of protein level alone and in combination with testosterone (vs. placebo) on changes in lean body mass (primary outcome), muscle strength, and physical function. A total of 154 men met the eligibility criteria; 112 completed a 2-week run-in period designed to evaluate compliance with the nutrition intervention. Of these, 92 subjects met compliance eligibility criteria and agreed to be randomized; 85% completed the full trial. The study successfully delivered three meals per day to subjects, with a high degree of compliance and subject satisfaction. Overall self-reported compliance rates were 80% and 93% for the meals and supplements, respectively. Details of compliance strategies are discussed. This community-based study design may serve as a model for longer-term nutritional interventions requiring monitoring of dietary compliance in a home-based feeding and supplementation trial.
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The SAZA study: implementing health financing reform in South Africa and Zambia.
Gilson, Lucy; Doherty, Jane; Lake, Sally; McIntyre, Di; Mwikisa, Chris; Thomas, Stephen
2003-03-01
This paper explores the policy-making process in the 1990s in two countries, South Africa and Zambia, in relation to health care financing reforms. While much of the analysis of health reform programmes has looked at design issues, assuming that a technically sound design is the primary requirement of effective policy change, this paper explores the political and bureaucratic realities shaping the pattern of policy change and its impacts. Through a case study approach, it provides a picture of the policy environment and processes in the two countries, specifically considering the extent to which technical analysts and technical knowledge were able to shape policy change. The two countries' experiences indicate the strong influence of political factors and actors over which health care financing policies were implemented, and which not, as well as over the details of policy design. Moments of political transition in both countries provided political leaders, specifically Ministers of Health, with windows of opportunity in which to introduce new policies. However, these transitions, and the changes in administrative structures introduced with them, also created environments that constrained the processes of reform design and implementation and limited the equity and sustainability gains achieved by the policies. Technical analysts, working either inside or outside government, had varying and often limited influence. In part, this reflected the limits of their own capacity as well as weaknesses in the way they were used in policy development. In addition, the analysts were constrained by the fact that their preferred policies often received only weak political support. Focusing almost exclusively on designing policy reforms, these analysts gave little attention to generating adequate support for the policy options they proposed. Finally, the country experiences showed that front-line health workers, middle level managers and the public had important influences over policy implementation and its impacts. The limited attention given to communicating policy changes to, or consulting with, these actors only heightened the potential for reforms to result in unanticipated and unwanted impacts. The strength of the paper lies in its 'thick description' of the policy process in each country, an empirical case study approach to policy that is under-represented in the literature. While such an approach allows only a cautious drawing of general conclusions, it suggests a number of ways in which to strengthen the implementation of financing policies in each country.
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NASA Astrophysics Data System (ADS)
Zhang, Ke; Cao, Ping; Ma, Guowei; Fan, Wenchen; Meng, Jingjing; Li, Kaihui
2016-07-01
Using the Chengmenshan Copper Mine as a case study, a new methodology for open pit slope design in karst-prone ground conditions is presented based on integrated stochastic-limit equilibrium analysis. The numerical modeling and optimization design procedure contain a collection of drill core data, karst cave stochastic model generation, SLIDE simulation and bisection method optimization. Borehole investigations are performed, and the statistical result shows that the length of the karst cave fits a negative exponential distribution model, but the length of carbonatite does not exactly follow any standard distribution. The inverse transform method and acceptance-rejection method are used to reproduce the length of the karst cave and carbonatite, respectively. A code for karst cave stochastic model generation, named KCSMG, is developed. The stability of the rock slope with the karst cave stochastic model is analyzed by combining the KCSMG code and the SLIDE program. This approach is then applied to study the effect of the karst cave on the stability of the open pit slope, and a procedure to optimize the open pit slope angle is presented.
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Assessing the first wave of epidemiological studies of nanomaterial workers
NASA Astrophysics Data System (ADS)
Liou, Saou-Hsing; Tsai, Candace S. J.; Pelclova, Daniela; Schubauer-Berigan, Mary K.; Schulte, Paul A.
2015-10-01
The results of early animal studies of engineered nanomaterials (ENMs) and air pollution epidemiology suggest that it is important to assess the health of ENM workers. Initial epidemiological studies of workers' exposure to ENMs (<100 nm) are reviewed and characterized for their study designs, findings, and limitations. Of the 15 studies, 11 were cross-sectional, 4 were longitudinal (1 was both cross-sectional and longitudinal in design), and 1 was a descriptive pilot study. Generally, the studies used biologic markers as the dependent variables. All 11 cross-sectional studies showed a positive relationship between various biomarkers and ENM exposures. Three of the four longitudinal studies showed a negative relationship; the fourth showed positive findings after a 1-year follow-up. Each study considered exposure to ENMs as the independent variable. Exposure was assessed by mass concentration in 10 studies and by particle count in six studies. Six of them assessed both mass and particle concentrations. Some of the studies had limited exposure data because of inadequate exposure assessment. Generally, exposure levels were not very high in comparison to those in human inhalation chamber studies, but there were some exceptions. Most studies involved a small sample size, from 2 to 258 exposed workers. These studies represent the first wave of epidemiological studies of ENM workers. They are limited by small numbers of participants, inconsistent (and in some cases inadequate) exposure assessments, generally low exposures, and short intervals between exposure and effect. Still, these studies are a foundation for future work; they provide insight into where ENM workers are experiencing potentially adverse effects that might be related to ENM exposures.
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USDA-ARS?s Scientific Manuscript database
While animal studies found vitamin K treatment reduced vascular calcification, human data are limited. Using a case-cohort design, we determined the association between vitamin K status and coronary artery calcium (CAC) progression in the Multi-ethnic Study of Atherosclerosis. Serum phylloquinone (v...
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What Factors Are Important in Smoking Cessation Amongst Deprived Communities?: A Qualitative Study
ERIC Educational Resources Information Center
Henderson, Hazel J.; Memon, Anjum; Lawson, Kate; Jacobs, Barbara; Koutsogeorgou, Eleni
2011-01-01
Objective: There is limited evidence regarding effective smoking cessation interventions in deprived communities. This study explored what factors are considered most important in smoking cessation, from the perspective of a group of NHS Stop Smoking Service users from a deprived community. Design: A qualitative study. Setting: A deprived…
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The Subjective Well-Being of Israeli Adolescents Attending Specialized School Classes
ERIC Educational Resources Information Center
Orkibi, Hod; Ronen, Tammie; Assoulin, Naama
2014-01-01
Although adolescents' well-being has long been considered a central goal in therapy and education, research focusing on the link between subjective well-being (SWB; happiness) and studying in specialized school classes is rather limited. Using a between-subjects design, the present study examined whether adolescents studying in sports, arts, or…
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Effectiveness of Software Training Using Simulations: An Exploratory Study
ERIC Educational Resources Information Center
McElroy, Arnold D., Jr.; Pan, Cheng-Chang
2009-01-01
This study was designed to explore the effectiveness in student performance and confidence of limited and full device simulators. The 30 employees from an information technology company who participated in this study were assigned to one of three groups. Each group received practice for learning a complex software procedure using traditional…
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An Analysis of a Plan to Improve Graduation Rates in Johnston County Schools
ERIC Educational Resources Information Center
Renfrow, David Ross
2015-01-01
There have been limited qualitative case studies exploring effective strategies designed to improve graduation rates in rural school districts. Specifically, few studies have presented information based solely upon the voices of practitioners themselves in solving the graduation crisis in America's public schools. This study will add to the…
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Impact of Contact Lens Material, Design, and Fitting on Discomfort.
Stapleton, Fiona; Tan, Jacqueline
2017-01-01
To review the effect of contact lens (CL) material, design, and fitting characteristics on CL discomfort. A PubMed search identified publications describing subjective comfort and CL material, fitting, and design parameters. The review included clinical signs associated with discomfort that may be a consequence of these parameters. Reduced lens movement or more CL tightness were associated with improved comfort. Increased lens-induced paralimbal conjunctival staining and indentation, considered as quasi-indicators of CL fitting or edge design, were also associated with better comfort. No recent studies have evaluated varying CL design parameters and subjective comfort. Silicone hydrogel CLs are no different in comfort compared with hydrogel CLs. Lower equilibrium water content is associated with improved comfort in hydrogel CL wear. Coefficient of friction shows promise as a material factor potentially associated with comfort. Lid wiper epitheliopathy and lid-parallel conjunctival folds have been linked with comfort in established wearers. Recent studies have confirmed the association between more mobile CLs and more discomfort, whereas closer conformity of the CL to the bulbar conjunctiva improved subjective comfort. There is no evidence to support the perceived comfort difference between silicone hydrogel and hydrogel CL. There has been limited progress in understanding the impact of varying specific CL design parameters. Although specific clinical signs may be predictive of discomfort, their role in the natural history of discomfort remains unclear. A better understanding of the relationship between coefficient of friction and comfort and strategies to improve lubricity may hold promise for limiting CL discomfort.
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Mi, Michael Y.; Betensky, Rebecca A.
2013-01-01
Background Currently, a growing placebo response rate has been observed in clinical trials for antidepressant drugs, a phenomenon that has made it increasingly difficult to demonstrate efficacy. The sequential parallel comparison design (SPCD) is a clinical trial design that was proposed to address this issue. The SPCD theoretically has the potential to reduce the sample size requirement for a clinical trial and to simultaneously enrich the study population to be less responsive to the placebo. Purpose Because the basic SPCD design already reduces the placebo response by removing placebo responders between the first and second phases of a trial, the purpose of this study was to examine whether we can further improve the efficiency of the basic SPCD and if we can do so when the projected underlying drug and placebo response rates differ considerably from the actual ones. Methods Three adaptive designs that used interim analyses to readjust the length of study duration for individual patients were tested to reduce the sample size requirement or increase the statistical power of the SPCD. Various simulations of clinical trials using the SPCD with interim analyses were conducted to test these designs through calculations of empirical power. Results From the simulations, we found that the adaptive designs can recover unnecessary resources spent in the traditional SPCD trial format with overestimated initial sample sizes and provide moderate gains in power. Under the first design, results showed up to a 25% reduction in person-days, with most power losses below 5%. In the second design, results showed up to a 8% reduction in person-days with negligible loss of power. In the third design using sample size re-estimation, up to 25% power was recovered from underestimated sample size scenarios. Limitations Given the numerous possible test parameters that could have been chosen for the simulations, the study’s results are limited to situations described by the parameters that were used, and may not generalize to all possible scenarios. Furthermore, drop-out of patients is not considered in this study. Conclusions It is possible to make an already complex design such as the SPCD adaptive, and thus more efficient, potentially overcoming the problem of placebo response at lower cost. Ultimately, such a design may expedite the approval of future effective treatments. PMID:23283576
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Thermal Control Subsystem Design for the Avionics of a Space Station Payload
NASA Technical Reports Server (NTRS)
Moran, Matthew E.
1996-01-01
A case study of the thermal control subsystem development for a space based payload is presented from the concept stage through preliminary design. This payload, the Space Acceleration Measurement System 2 (SAMS-2), will measure the acceleration environment at select locations within the International Space Station. Its thermal control subsystem must maintain component temperatures within an acceptable range over a 10 year life span, while restricting accessible surfaces to touch temperature limits and insuring fail safe conditions in the event of loss of cooling. In addition to these primary design objectives, system level requirements and constraints are imposed on the payload, many of which are driven by multidisciplinary issues. Blending these issues into the overall system design required concurrent design sessions with the project team, iterative conceptual design layouts, thermal analysis and modeling, and hardware testing. Multiple tradeoff studies were also performed to investigate the many options which surfaced during the development cycle.
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Applications of Ontology Design Patterns in Biomedical Ontologies
Mortensen, Jonathan M.; Horridge, Matthew; Musen, Mark A.; Noy, Natalya F.
2012-01-01
Ontology design patterns (ODPs) are a proposed solution to facilitate ontology development, and to help users avoid some of the most frequent modeling mistakes. ODPs originate from similar approaches in software engineering, where software design patterns have become a critical aspect of software development. There is little empirical evidence for ODP prevalence or effectiveness thus far. In this work, we determine the use and applicability of ODPs in a case study of biomedical ontologies. We encoded ontology design patterns from two ODP catalogs. We then searched for these patterns in a set of eight ontologies. We found five patterns of the 69 patterns. Two of the eight ontologies contained these patterns. While ontology design patterns provide a vehicle for capturing formally reoccurring models and best practices in ontology design, we show that today their use in a case study of widely used biomedical ontologies is limited. PMID:23304337
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Challenges of Obtaining Evidence-Based Information Regarding Medications and Male Fertility.
Drobnis, Erma Z; Nangia, Ajay K
2017-01-01
In the clinic, the existing literature is insufficient to counsel our infertile men on medication use. Most studies have flaws that limit their application to evidence-based practice. In this chapter, we discuss the limitations of the current literature and the challenges to designing more useful studies. Among the most important weaknesses of existing studies is lack of power; that is, too few men are included to draw conclusions about the existence and size of medication effects. Adequate power is particularly important when confirming an absence of medication effect. Bias is also a problem in most studies. Early studies were rarely randomized, placebo-controlled, or blinded; a common example is patients receiving different medication regimes based on the severity of their symptoms-making it impossible to attribute differences between treated and untreated men to the medications. Additional bias is introduced by failing to include other factors that influence the outcome in the experimental design. A uniform population amenable to randomization and placebo-control are experimental species, and useful information has been gained from these models. However, application to humans is limited by differences from other species in route of drug administration, absorption of the drug, concentration in the male genital tract tissues, and genital tract physiology. To a lesser degree, there is variation among individual men in their response to drugs. In addition, drugs in the same class may have different effects, limiting the applicability of data across drugs of a single class. Complicating matters further, a toxic medication may seem to improve fertility endpoints by improving a disease condition that diminishes fertility. Finally, drug interactions have not been studied, and actual fertility data (pregnancy/fecundity) in humans are rare. A healthy dose of skepticism is warranted when evaluating studies of medications and male reproductive health.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-11-21
...) Study. (A) F-2 post-secondary/vocational study. (1) Authorized Study at SEVP-Certified Schools. An F-2... Assignment and Study by F-2 and M-2 Nonimmigrants AGENCY: U.S. Immigration and Customs Enforcement, DHS... programs and increase opportunities for study by spouses and children of nonimmigrant students. The...
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Obesity and the community food environment: a systematic review.
Holsten, Joanna E
2009-03-01
To examine the relationship between obesity and the community and/or consumer food environment. A comprehensive literature search of multiple databases was conducted and seven studies were identified for review. Studies were selected if they measured BMI and environmental variables related to food outlets. Environmental variables included the geographic arrangement of food stores or restaurants in communities and consumer conditions such as food price and availability within each outlet. The study designs, methods, limitations and results related to obesity and the food environment were reviewed, and implications for future research were synthesized. The reviewed studies used cross-sectional designs to examine the community food environment defined as the number per capita, proximity or density of food outlets. Most studies indirectly identified food outlets through large databases. The studies varied substantially in sample populations, outcome variables, units of measurement and data analysis. Two studies did not find any significant association between obesity rates and community food environment variables. Five studies found significant results. Many of the studies were subject to limitations that may have mitigated the validity of the results. Research examining obesity and the community or consumer food environment is at an early stage. The most pertinent gaps include primary data at the individual level, direct measures of the environment, studies examining the consumer environment and study designs involving a time sequence. Future research should directly measure multiple levels of the food environment and key confounders at the individual level.
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ERIC Educational Resources Information Center
Gomez-Lanier, Lilia
2017-01-01
Experiential education programs, such as international and domestic study tours, bridge the limitations of formal learning classroom by allowing students to experience reality in a new learning dimension. This mixed-methods study explores experiential learning during a domestic interior design study tour to New York City and an international…
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Saunders, Gabrielle H; Biswas, Kousick; Serpi, Tracey; McGovern, Stephanie; Groer, Shirley; Stock, Eileen M; Magruder, Kathryn M; Storzbach, Daniel; Skelton, Kelly; Abrams, Thad; McCranie, Mark; Richerson, Joan; Dorn, Patricia A; Huang, Grant D; Fallon, Michael T
2017-11-01
Posttraumatic stress disorder (PTSD) is a leading cause of impairments in quality of life and functioning among Veterans. Service dogs have been promoted as an effective adjunctive intervention for PTSD, however published research is limited and design and implementation flaws in published studies limit validated conclusions. This paper describes the rationale for the study design, a detailed methodological description, and implementation challenges of a multisite randomized clinical trial examining the impact of service dogs on the on the functioning and quality of life of Veterans with PTSD. Trial design considerations prioritized participant and intervention (dog) safety, selection of an intervention comparison group that would optimize enrollment in all treatment arms, pragmatic methods to ensure healthy well-trained dogs, and the selection of outcomes for achieving scientific and clinical validity in a Veteran PTSD population. Since there is no blueprint for conducting a randomized clinical trial examining the impact of dogs on PTSD of this size and scope, it is our primary intent that the successful completion of this trial will set a benchmark for future trial design and scientific rigor, as well as guiding researchers aiming to better understand the role that dogs can have in the management of Veterans experiencing mental health conditions such as PTSD. Published by Elsevier Inc.
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Dimairo, Munyaradzi; Julious, Steven A; Todd, Susan; Nicholl, Jonathan P; Boote, Jonathan
2015-12-23
Appropriately conducted adaptive designs (ADs) offer many potential advantages over conventional trials. They make better use of accruing data, potentially saving time, trial participants, and limited resources compared to conventional, fixed sample size designs. However, one can argue that ADs are not implemented as often as they should be, particularly in publicly funded confirmatory trials. This study explored barriers, concerns, and potential facilitators to the appropriate use of ADs in confirmatory trials among key stakeholders. We conducted three cross-sectional, online parallel surveys between November 2014 and January 2015. The surveys were based upon findings drawn from in-depth interviews of key research stakeholders, predominantly in the UK, and targeted Clinical Trials Units (CTUs), public funders, and private sector organisations. Response rates were as follows: 30(55 %) UK CTUs, 17(68 %) private sector, and 86(41 %) public funders. A Rating Scale Model was used to rank barriers and concerns in order of perceived importance for prioritisation. Top-ranked barriers included the lack of bridge funding accessible to UK CTUs to support the design of ADs, limited practical implementation knowledge, preference for traditional mainstream designs, difficulties in marketing ADs to key stakeholders, time constraints to support ADs relative to competing priorities, lack of applied training, and insufficient access to case studies of undertaken ADs to facilitate practical learning and successful implementation. Associated practical complexities and inadequate data management infrastructure to support ADs were reported as more pronounced in the private sector. For funders of public research, the inadequate description of the rationale, scope, and decision-making criteria to guide the planned AD in grant proposals by researchers were all viewed as major obstacles. There are still persistent and important perceptions of individual and organisational obstacles hampering the use of ADs in confirmatory trials research. Stakeholder perceptions about barriers are largely consistent across sectors, with a few exceptions that reflect differences in organisations' funding structures, experiences and characterisation of study interventions. Most barriers appear connected to a lack of practical implementation knowledge and applied training, and limited access to case studies to facilitate practical learning.
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50 CFR 660.230 - Fixed gear fishery-management measures.
Code of Federal Regulations, 2012 CFR
2012-10-01
... limit, size limit, scientific sorting designation, quota, harvest guideline, ACL or ACT or OY, if the... designation, quota, harvest guideline, ACL or ACT or OY applied.” The States of Washington, Oregon, and...
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50 CFR 660.230 - Fixed gear fishery-management measures.
Code of Federal Regulations, 2011 CFR
2011-10-01
... limit, size limit, scientific sorting designation, quota, harvest guideline, ACL or ACT or OY, if the... designation, quota, harvest guideline, ACL or ACT or OY applied.” The States of Washington, Oregon, and...
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Leblond, Frederic; Tichauer, Kenneth M.; Pogue, Brian W.
2010-01-01
The spatial resolution and recovered contrast of images reconstructed from diffuse fluorescence tomography data are limited by the high scattering properties of light propagation in biological tissue. As a result, the image reconstruction process can be exceedingly vulnerable to inaccurate prior knowledge of tissue optical properties and stochastic noise. In light of these limitations, the optimal source-detector geometry for a fluorescence tomography system is non-trivial, requiring analytical methods to guide design. Analysis of the singular value decomposition of the matrix to be inverted for image reconstruction is one potential approach, providing key quantitative metrics, such as singular image mode spatial resolution and singular data mode frequency as a function of singular mode. In the present study, these metrics are used to analyze the effects of different sources of noise and model errors as related to image quality in the form of spatial resolution and contrast recovery. The image quality is demonstrated to be inherently noise-limited even when detection geometries were increased in complexity to allow maximal tissue sampling, suggesting that detection noise characteristics outweigh detection geometry for achieving optimal reconstructions. PMID:21258566
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The MANIFEST prototyping design study
NASA Astrophysics Data System (ADS)
Lawrence, Jonathan S.; Ben-Ami, Sagi; Brown, David M.; Brown, Rebecca A.; Case, Scott; Chapman, Steve; Churilov, Vladimir; Colless, Matthew; Content, Robert; Depoy, Darren; Evans, Ian; Farrell, Tony; Goodwin, Michael; Jacoby, George; Klauser, Urs; Kuehn, Kyler; Lorente, Nuria P. F.; Mali, Slavko; Marshall, Jennifer; Muller, Rolf; Nichani, Vijay; Pai, Naveen; Prochaska, Travis; Saunders, Will; Schmidt, Luke; Shortridge, Keith; Staszak, Nicholas F.; Szentgyorgyi, Andrew; Tims, Julia; Vuong, Minh V.; Waller, Lewis G.; Zhelem, Ross
2016-08-01
MANIFEST is a facility multi-object fibre system for the Giant Magellan Telescope, which uses `Starbug' fibre positioning robots. MANIFEST, when coupled to the telescope's planned seeing-limited instruments, GMACS, and G-CLEF, offers access to: larger fields of view; higher multiplex gains; versatile reformatting of the focal plane via IFUs; image-slicers; and in some cases higher spatial and spectral resolution. The Prototyping Design Study phase for MANIFEST, nearing completion, has focused on developing a working prototype of a Starbugs system, called TAIPAN, for the UK Schmidt Telescope, which will conduct a stellar and galaxy survey of the Southern sky. The Prototyping Design Study has also included work on the GMT instrument interfaces. In this paper, we outline the instrument design features of TAIPAN, highlight the modifications that will be necessary for the MANIFEST implementation, and provide an update on the MANIFEST/instrument interfaces.
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The Use and Interpretation of Quasi-Experimental Studies in Medical Informatics
Harris, Anthony D.; McGregor, Jessina C.; Perencevich, Eli N.; Furuno, Jon P.; Zhu, Jingkun; Peterson, Dan E.; Finkelstein, Joseph
2006-01-01
Quasi-experimental study designs, often described as nonrandomized, pre-post intervention studies, are common in the medical informatics literature. Yet little has been written about the benefits and limitations of the quasi-experimental approach as applied to informatics studies. This paper outlines a relative hierarchy and nomenclature of quasi-experimental study designs that is applicable to medical informatics intervention studies. In addition, the authors performed a systematic review of two medical informatics journals, the Journal of the American Medical Informatics Association (JAMIA) and the International Journal of Medical Informatics (IJMI), to determine the number of quasi-experimental studies published and how the studies are classified on the above-mentioned relative hierarchy. They hope that future medical informatics studies will implement higher level quasi-experimental study designs that yield more convincing evidence for causal links between medical informatics interventions and outcomes. PMID:16221933
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Typing single polymorphic nucleotides in mitochondrial DNA as a way to access Middle Pleistocene DNA
Valdiosera, Cristina; García, Nuria; Dalén, Love; Smith, Colin; Kahlke, Ralf-Dietrich; Lidén, Kerstin; Angerbjörn, Anders; Arsuaga, Juan Luis; Götherström, Anders
2006-01-01
In this study, we have used a technique designed to target short fragments containing informative mitochondrial substitutions to extend the temporal limits of DNA recovery and study the molecular phylogeny of Ursus deningeri. We present a cladistic analysis using DNA recovered from 400 kyr old U. deningeri remains, which demonstrates U. deningeri's relation to Ursus spelaeus. This study extends the limits of recovery from skeletal remains by almost 300 kyr. Plant material from permafrost environments has yielded DNA of this age in earlier studies, and our data suggest that DNA in teeth from cave environments may be equally well preserved. PMID:17148299
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-03-26
... will be cancelled. \\4\\ See BOX Rule 7110(c). The Limit Up/Limit-Down Plan is designed to prevent... designed to promote just and equitable principles of trade, to remove impediments to and perfect the... the public interest. Specifically, the Exchange believes that the proposal is designed to help...
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Real-time PCR probe optimization using design of experiments approach.
Wadle, S; Lehnert, M; Rubenwolf, S; Zengerle, R; von Stetten, F
2016-03-01
Primer and probe sequence designs are among the most critical input factors in real-time polymerase chain reaction (PCR) assay optimization. In this study, we present the use of statistical design of experiments (DOE) approach as a general guideline for probe optimization and more specifically focus on design optimization of label-free hydrolysis probes that are designated as mediator probes (MPs), which are used in reverse transcription MP PCR (RT-MP PCR). The effect of three input factors on assay performance was investigated: distance between primer and mediator probe cleavage site; dimer stability of MP and target sequence (influenza B virus); and dimer stability of the mediator and universal reporter (UR). The results indicated that the latter dimer stability had the greatest influence on assay performance, with RT-MP PCR efficiency increased by up to 10% with changes to this input factor. With an optimal design configuration, a detection limit of 3-14 target copies/10 μl reaction could be achieved. This improved detection limit was confirmed for another UR design and for a second target sequence, human metapneumovirus, with 7-11 copies/10 μl reaction detected in an optimum case. The DOE approach for improving oligonucleotide designs for real-time PCR not only produces excellent results but may also reduce the number of experiments that need to be performed, thus reducing costs and experimental times.
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Bernstein, Judith A; Bernstein, Edward; Heeren, Timothy C
2010-09-01
Reductions in control group consumption over time that are possibly related to research design affect the impact of brief alcohol interventions (BAI) in clinical settings. We conducted a systematic review to identify research design factors that may contribute to control group change, strategies to limit these effects and implications for researchers. Studies with control group n > 30 were selected if they published baseline and outcome consumption data, conducted trials in clinical settings in Anglophone countries and did not censor gender or age. Among 38 studies cited in 20 reviews through October 2009, 16 met criteria (n = 31-370). In 54%, controls received alcohol specific handouts, advice and/or referral. Both the number and depth of assessments were highly variable. The percentage change in consumption ranged from-0.10 to-0.84 (mean-0.32), and effect size from 0.04 to 0.70 (mean 0.37). Published data were insufficient for meta-analysis. Researchers should consider strategies to reduce the impact of research design factors, such as procedures to enhance sample diversity, blind subjects to study purpose to limit social desirability bias, reduce the number and depth of instruments (assessment reactivity), and finally, analytic techniques to decrease the impact of outliers and regression to the mean. This review identifies problems with retrospective analysis of predictors of control group change, and underscores the need to design prospective studies to permit identification, quantification and adjustment for potential sources of bias in BAI trials.
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NASA Astrophysics Data System (ADS)
Meng, Q. Y.; Svendsgaard, D.; Kotchmar, D. J.; Pinto, J. P.
2012-09-01
Although positive associations between ambient NO2 concentrations and personal exposures have generally been found by exposure studies, the strength of the associations varied among studies. Differences in results could be related to differences in study design and in exposure factors. However, the effects of study design, exposure factors, and sampling and measurement errors on the strength of the personal-ambient associations have not been evaluated quantitatively in a systematic manner. A quantitative research synthesis was conducted to examine these issues based on peer-reviewed publications in the past 30 years. Factors affecting the strength of the personal-ambient associations across the studies were also examined with meta-regression. Ambient NO2 was found to be significantly associated with personal NO2 exposures, with estimates of 0.42, 0.16, and 0.72 for overall pooled, longitudinal and daily average correlation coefficients based on random-effects meta-analysis. This conclusion was robust after correction for publication bias with correlation coefficients of 0.37, 0.16 and 0.45. We found that season and some population characteristics, such as pre-existing disease, were significant factors affecting the strength of the personal-ambient associations. More meaningful and rigorous comparisons would be possible if greater detail were published on the study design (e.g. local and indoor sources, housing characteristics, etc.) and data quality (e.g., detection limits and percent of data above detection limits).
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Seckler, Tobias; Jagielski, Kai; Stunder, Dominik
2015-01-01
Electromagnetic interference is a concern for people wearing cardiovascular implantable electronic devices (CIEDs). The aim of this study was to assess the electromagnetic compatibility between CIEDs and the magnetic field of a common wireless charging technology. To do so the voltage induced in CIEDs by Qi A13 design magnetic fields were measured and compared with the performance limits set by ISO 14117. In order to carry this out a measuring circuit was developed which can be connected with unipolar or bipolar pacemaker leads. The measuring system was positioned at the four most common implantation sites in a torso phantom filled with physiological saline solution. The phantom was exposed by using Helmholtz coils from 5 µT to 27 µT with 111 kHz sine-bursts or by using a Qi A13 design wireless charging board (Qi-A13-Board) in two operating modes “power transfer” and “pinging”. With the Helmholtz coils the lowest magnetic flux density at which the performance limit was exceeded is 11 µT. With the Qi-A13-Board in power transfer mode 10.8% and in pinging mode 45.7% (2.2% at 10 cm distance) of the performance limit were reached at maximum. In neither of the scrutinized cases, did the voltage induced by the Qi-A13-Board exceed the performance limits. PMID:26024360
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Seckler, Tobias; Jagielski, Kai; Stunder, Dominik
2015-05-27
Electromagnetic interference is a concern for people wearing cardiovascular implantable electronic devices (CIEDs). The aim of this study was to assess the electromagnetic compatibility between CIEDs and the magnetic field of a common wireless charging technology. To do so the voltage induced in CIEDs by Qi A13 design magnetic fields were measured and compared with the performance limits set by ISO 14117. In order to carry this out a measuring circuit was developed which can be connected with unipolar or bipolar pacemaker leads. The measuring system was positioned at the four most common implantation sites in a torso phantom filled with physiological saline solution. The phantom was exposed by using Helmholtz coils from 5 µT to 27 µT with 111 kHz sine‑bursts or by using a Qi A13 design wireless charging board (Qi‑A13‑Board) in two operating modes "power transfer" and "pinging". With the Helmholtz coils the lowest magnetic flux density at which the performance limit was exceeded is 11 µT. With the Qi‑A13‑Board in power transfer mode 10.8% and in pinging mode 45.7% (2.2% at 10 cm distance) of the performance limit were reached at maximum. In neither of the scrutinized cases, did the voltage induced by the Qi‑A13‑Board exceed the performance limits.
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A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ren, J.; Zuo, G. Z.; Hu, J. S.
2015-02-15
A program involving the extensive and systematic use of lithium (Li) as a “first,” or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak—both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thinmore » flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST.« less
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QMI: Rising to the Space Station Design Challenge
NASA Astrophysics Data System (ADS)
Carswell, W. E.; Farmer, J.; Coppens, C.; Breeding, S.; Rose, F.
2002-01-01
The Quench Module Insert (QMI) materials processing furnace is being designed to operate for 8000 hours over four years on the International Space Station as part of the first Materials Science Research Rack of the Materials Science Research Facility. The Bridgman-type furnace is being built for the directional solidification processing of metals and alloys in the microgravity environment of space. Most notably it will be used for processing aluminum and related alloys. Designing for the space station environment presents intriguing design challenges in the form of a ten-year life requirement coupled with both limited opportunities for maintenance and resource constraints in the form of limited power and space. The long life requirement has driven the design of several features in the furnace, including the design of the heater core, the selection and placement of the thermocouples, overall performance monitoring, and the design of the chill block. The power and space limitations have been addressed through a compact furnace design using efficient vacuum insulation. Details on these design features, as well as development test performance results to date, are presented.
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QMI: Rising to the Space Station Design Challenge
NASA Technical Reports Server (NTRS)
Carswell, W. E.; Farmer, J.; Coppens, C.; Breeding, S.; Rose, F.; Curreri, Peter A. (Technical Monitor)
2002-01-01
The Quench Module Insert (QMI) materials processing furnace is being designed to operate for 8000 hours over four years on the International Space Station (ISS) as part of the first Materials Science Research Rack (MSRR-1) of the Materials Science Research Facility (MSRF). The Bridgman-type furnace is being built for the directional solidification processing of metals and alloys in the microgravity environment of space. Most notably it will be used for processing aluminum and related alloys. Designing for the space station environment presents intriguing design challenges in the form of a ten-year life requirement coupled with both limited opportunities for maintenance and resource constraints in the form of limited power and space. The long life requirement has driven the design of several features in the furnace, including the design of the heater core, the selection and placement of the thermocouples, overall performance monitoring, and the design of the chill block. The power and space limitations have been addressed through a compact furnace design using efficient vacuum insulation. Details on these design features, as well as development test performance results to date, are presented.
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NASA Astrophysics Data System (ADS)
Mandal, Saptarshi; Agarwal, Anchal; Ahmadi, Elaheh; Mahadeva Bhat, K.; Laurent, Matthew A.; Keller, Stacia; Chowdhury, Srabanti
2017-08-01
In this work, a study of two different types of current aperture vertical electron transistor (CAVET) with ion-implanted blocking layer are presented. The device fabrication and performance limitation of a CAVET with a dielectric gate is discussed, and the breakdown limiting structure is evaluated using on-wafer test structures. The gate dielectric limited the device breakdown to 50V, while the blocking layer was able to withstand over 400V. To improve the device performance, an alternative CAVET structure with a p-GaN gate instead of dielectric is designed and realized. The pGaN gated CAVET structure increased the breakdown voltage to over 400V. Measurement of test structures on the wafer showed the breakdown was limited by the blocking layer instead of the gate p-n junction.
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Currens, C.R.; Liss, W.J.; Hoffman, R.L.
2007-01-01
The formation of amphibian population structure is directly affected by predation. Although aquatic predators have been shown to have direct negative effects on larval salamanders in laboratory and field experiments, the potential impacts of gape-limited fish on larval salamander growth has been largely underexplored. We designed an enclosure experiment conducted in situ to quantify the effects of gape-limited Brook Trout (Salvelinus fontinalis) on larval Northwestern Salamander (Ambystoma gracile) growth. We specifically tested whether the presence of fish too small to consume larvae had a negative effect on larval growth. The results of this study indicate that the presence of a gape-limited S. fontinalis can have a negative effect on growth of larval A. gracile salamanders. Copyright 2007 Society for the Study of Amphibians and Reptiles.
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DOT National Transportation Integrated Search
2013-06-01
The objective of the proposed study is to design, test, and evaluate high-volume fly ash concrete mixtures. Traditional specifications : limit the amount of fly ash to 40% or less cement replacement. This program attempts to increase the ash content ...
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NASA Astrophysics Data System (ADS)
Lin, Tzu-Yung; Green, Roger J.; O'Connor, Peter B.
2011-12-01
The nature of the ion signal from a 12-T Fourier-transform ion cyclotron resonance mass spectrometer and the electronic noise were studied to further understand the electronic detection limit. At minimal cost, a new transimpedance preamplifier was designed, computer simulated, built, and tested. The preamplifier design pushes the electronic signal-to-noise performance at room temperature to the limit, because of its enhanced tolerance of the capacitance of the detection device, lower intrinsic noise, and larger flat mid-band gain (input current noise spectral density of around 1 pA/sqrt{Hz} when the transimpedance is about 85 dBΩ). The designed preamplifier has a bandwidth of ˜3 kHz to 10 MHz, which corresponds to the mass-to-charge ratio, m/z, of approximately 18 to 61 k at 12 T. The transimpedance and the bandwidth can be easily adjusted by changing the value of passive components. The feedback limitation of the circuit is discussed. With the maximum possible transimpedance of 5.3 MΩ when using an 0402 surface mount resistor, the preamplifier was estimated to be able to detect ˜110 charges in a single scan.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Lin, Tzu-Yung; Green, Roger J.; O'Connor, Peter B.
2011-12-15
The nature of the ion signal from a 12-T Fourier-transform ion cyclotron resonance mass spectrometer and the electronic noise were studied to further understand the electronic detection limit. At minimal cost, a new transimpedance preamplifier was designed, computer simulated, built, and tested. The preamplifier design pushes the electronic signal-to-noise performance at room temperature to the limit, because of its enhanced tolerance of the capacitance of the detection device, lower intrinsic noise, and larger flat mid-band gain (input current noise spectral density of around 1 pA/{radical}(Hz) when the transimpedance is about 85 dB{Omega}). The designed preamplifier has a bandwidth of {approx}3more » kHz to 10 MHz, which corresponds to the mass-to-charge ratio, m/z, of approximately 18 to 61 k at 12 T. The transimpedance and the bandwidth can be easily adjusted by changing the value of passive components. The feedback limitation of the circuit is discussed. With the maximum possible transimpedance of 5.3 M{Omega} when using an 0402 surface mount resistor, the preamplifier was estimated to be able to detect {approx}110 charges in a single scan.« less
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Microfluidic converging/diverging channels optimised for homogeneous extensional deformation.
Zografos, K; Pimenta, F; Alves, M A; Oliveira, M S N
2016-07-01
In this work, we optimise microfluidic converging/diverging geometries in order to produce constant strain-rates along the centreline of the flow, for performing studies under homogeneous extension. The design is examined for both two-dimensional and three-dimensional flows where the effects of aspect ratio and dimensionless contraction length are investigated. Initially, pressure driven flows of Newtonian fluids under creeping flow conditions are considered, which is a reasonable approximation in microfluidics, and the limits of the applicability of the design in terms of Reynolds numbers are investigated. The optimised geometry is then used for studying the flow of viscoelastic fluids and the practical limitations in terms of Weissenberg number are reported. Furthermore, the optimisation strategy is also applied for electro-osmotic driven flows, where the development of a plug-like velocity profile allows for a wider region of homogeneous extensional deformation in the flow field.
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NASA Technical Reports Server (NTRS)
Lester, H. C.; Posey, J. W.
1976-01-01
A discrete frequency study is made of the influence of source characteristics on the optimal properties of acoustically lined uniform and two section ducts. Two simplified sources, a plane wave and a monopole, are considered in some detail and over a greater frequency range than has been previously studied. Source and termination impedance effects are given limited examination. An example of a turbomachinery source and three associated source variants is also presented. Optimal liner designs based on modal theory approach the Cremer criterion at low frequencies and the geometric acoustics limit at high frequencies. Over an intermediate frequency range, optimal two section liners produced higher transmission losses than did the uniform configurations. Source distribution effects were found to have a significant effect on optimal liner design, but source and termination impedance effects appear to be relatively unimportant.
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Microfluidic converging/diverging channels optimised for homogeneous extensional deformation
Zografos, K.; Oliveira, M. S. N.
2016-01-01
In this work, we optimise microfluidic converging/diverging geometries in order to produce constant strain-rates along the centreline of the flow, for performing studies under homogeneous extension. The design is examined for both two-dimensional and three-dimensional flows where the effects of aspect ratio and dimensionless contraction length are investigated. Initially, pressure driven flows of Newtonian fluids under creeping flow conditions are considered, which is a reasonable approximation in microfluidics, and the limits of the applicability of the design in terms of Reynolds numbers are investigated. The optimised geometry is then used for studying the flow of viscoelastic fluids and the practical limitations in terms of Weissenberg number are reported. Furthermore, the optimisation strategy is also applied for electro-osmotic driven flows, where the development of a plug-like velocity profile allows for a wider region of homogeneous extensional deformation in the flow field. PMID:27478523
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Aligning Accreditation and Academic Program Reviews: A Canadian Case Study
ERIC Educational Resources Information Center
Bowker, Lynne
2017-01-01
Purpose: This paper aims to investigate the potential benefits and limitations associated with aligning accreditation and academic program reviews in post-secondary institutions, using a descriptive case study approach. Design/methodology/approach: The paper describes two Canadian graduate programs that are subject to both external professional…
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Korean Elementary School Students' Perceptions of Relationship with Marine Organisms
ERIC Educational Resources Information Center
Kim, Jong-Mun; Anderson, David; Scott, Sandra
2013-01-01
This exploratory study examined the perceptions of, and relationship with, marine organisms of 81 urban sixth grade Korean students using a specifically designed survey questionnaire. The study outcomes revealed that these Korean students have limited experience with and different levels of connectedness to marine organisms. Viewed through…
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34 CFR 656.30 - What are allowable costs and limitations on allowable costs?
Code of Federal Regulations, 2010 CFR
2010-07-01
... FOREIGN LANGUAGE AND AREA STUDIES OR FOREIGN LANGUAGE AND INTERNATIONAL STUDIES What Conditions Must Be...) Library acquisitions; (3) Teaching and research materials; (4) Curriculum planning and development; (5...; and (8) Summer institutes in the United States or abroad designed to provide language and area...
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Origins, Methods and Advances in Qualitative Meta-Synthesis
ERIC Educational Resources Information Center
Nye, Elizabeth; Melendez-Torres, G. J.; Bonell, Chris
2016-01-01
Qualitative research is a broad term encompassing many methods. Critiques of the field of qualitative research argue that while individual studies provide rich descriptions and insights, the absence of connections drawn between studies limits their usefulness. In response, qualitative meta-synthesis serves as a design to interpret and synthesise…
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Plants. Environmental Education Curriculum.
ERIC Educational Resources Information Center
Topeka Public Schools, KS.
The study of plants is often limited to studying plant structure with little emphasis on the vital role plants play in our natural system and the variety of ways man uses plants. This unit, designed for intermediate level elementary students, reviews basic plant structure, discusses roles of plants in nature's system, illustrates plant…
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Developing a Short-Term, Faculty-Led Sports Medicine Study Abroad Experience
ERIC Educational Resources Information Center
Jutte, Lisa S.
2011-01-01
Context: While sports medicine study abroad opportunities have recently increased, the literature regarding their development is non-existent in athletic training education literature and very limited in general education literature. Objective: The purpose of this manuscript is to draw upon my experience to describe the essential design elements…
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High-Dose Vitamin C (PDQ®)—Health Professional Version
High-dose vitamin C, with and without conventional cancer therapies, appeared promising in early studies and was well tolerated. However, these studies have several limitations due to lack of rigor in trial design. Get detailed information about high-dose vitamin C in cancer in this clinician summary.
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A Course of Study in Cooperation and Cooperatives.
ERIC Educational Resources Information Center
Bjoraker, Walter T., Ed.
Designed for teachers with limited experience in cooperatives, this course of study was prepared by seminar students for use in high school or adult education programs, and emphasizes the principles of cooperation, the operation and management of cooperatives, and the communication required for their effective functioning. Units requiring a total…
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ERIC Educational Resources Information Center
McClintic, Sandra; Petty, Karen
2015-01-01
This qualitative case study explored how early childhood teachers' beliefs and practices influence the function of preschool outdoor play. Teachers believed that supervision was paramount. They perceived that the physical design of the outdoor environment posed limitations for planning, preparation, and implementation. Teachers' recollections of…
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Is Infertility Associated with Childhood Autism?
ERIC Educational Resources Information Center
Grether, Judith K.; Qian, Yinge; Croughan, Mary S.; Wu, Yvonne W.; Schembri, Michael; Camarano, Loretta; Croen, Lisa A.
2013-01-01
Concerns persist about a possible link between infertility and risk of autism spectrum disorders (ASD). Interpretation of existing studies is limited by racial/ethnic homogeneity of study populations and other factors. Using a case-control design, we evaluated infertility history and treatment documented in medical records of members of Kaiser…
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Adult Beginner Instrumentalists' Practice, Self-Regulation, and Self-Efficacy: A Pilot Study
ERIC Educational Resources Information Center
Ritchie, Laura; Kearney, Phil
2018-01-01
The self-regulation of practice behaviour has repeatedly been shown to distinguish between novice and expert performers, however interventions designed to encourage self-regulation by novice musicians have shown limited effectiveness. Guided by successful research in sporting contexts, the present study investigated the behaviours of beginner…
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Export Market Orientation Behavior of Universities: The British Scenario
ERIC Educational Resources Information Center
Asaad, Yousra; Melewar, T. C.; Cohen, Geraldine
2015-01-01
This study seeks to extend our knowledge of export market orientation (EMO) in the context of British universities with regard to recruitment of international students. Export marketing remains an area of limited focus in the marketization of higher education literature. The study predominantly follows a quantitative research design using survey…
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Reed, Darcy A; Fletcher, Kathlyn E; Arora, Vineet M
2010-12-21
The Accreditation Council for Graduate Medical Education's new duty-hour standards limit interns' shifts to 16 hours and night float to 6 consecutive nights. Protected sleep time (that is, "nap") is strongly encouraged. As duty-hour reforms are implemented, examination of the quality and outcomes of the relevant literature is important. To systematically review the literature examining shift length, protected sleep time, and night float. MEDLINE, PREMEDLINE, and EMBASE from January 1989 through May 2010. Studies examined the associations of shift length, protected sleep time, or night float with patient care, resident health, and education outcomes among residents in practice settings. Study quality was measured by using the validated Medical Education Research Study Quality Instrument and the U.S. Preventive Services Task Force criteria. Two investigators independently rated study quality, and interrater agreement was calculated. Sixty-four studies met inclusion criteria. Most studies used single-group cross-sectional (19 studies [29.7%]) or pre-post (41 studies [64.1%]) designs, and 4 (6.3%) were randomized, controlled trials. Five studies (7.8%) were multi-institutional. Twenty-four of 33 (72.7%) studies examining shift length reported that shorter shifts were associated with decreased medical errors, motor vehicle crashes, and percutaneous injuries. Only 2 studies assessed protected sleep time and reported that residents' adherence to naps was poor. Night floats described in 33 studies involved 5 to 7 consecutive nights. Most studies used single-institution, observational designs. Publication bias is likely but difficult to assess in this methodologically weak and heterogeneous body of evidence. For the limited outcomes measured, most studies supported reducing shift length but did not adequately address the optimal shift duration. Studies had numerous methodological limitations and unclear generalizability for most outcomes. Specific recommendations about shift length, protected sleep time, and night float should acknowledge the limitations of this evidence. Accreditation Council for Graduate Medical Education.
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Alcohol Policies and Suicide: A Review of the Literature
Xuan, Ziming; Naimi, Timothy S.; Kaplan, Mark S.; Bagge, Courtney L.; Few, Lauren R.; Maisto, Stephen; Saitz, Richard; Freeman, Robert
2016-01-01
Both intoxication and chronic heavy alcohol use are associated with suicide. There is extensive population-level evidence linking per capita alcohol consumption with suicide. While alcohol policies can reduce excessive alcohol consumption, the relationship between alcohol policies and suicide warrants a critical review of the literature. This review summarizes the associations between various types of alcohol policies and suicide, both in the United States and internationally, as presented in English-language literature published between 1999 and 2014. Study designs, methodological challenges, and limitations in ascertaining the associations are discussed. Because of the substantial between-states variation in alcohol policies, U.S.-based studies contributed substantially to the literature. Repeated cross-sectional designs at both the ecological level and decedent level were common among U.S.-based studies. Non-U.S. studies often used time series data to evaluate pre-post comparisons of a hybrid set of policy changes. Although inconsistency remained, the published literature in general supported the protective effect of restrictive alcohol policies on reducing suicide as well as the decreased level of alcohol involvement among suicide decedents. Common limitations included measurement and selection bias, and a focus on effects of a limited number of alcohol policies without accounting for other alcohol policies. This review summarizes a number of studies that suggest restrictive alcohol policies may contribute to suicide prevention on a general population level, and to a reduction of alcohol involvement among suicide deaths. PMID:27618526
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Heterogeneous Mixtures as NLO Christiansen Filters for Optical Limiting
DOE Office of Scientific and Technical Information (OSTI.GOV)
Exarhos, Gregory J.; Ferris, Kim F.; Samuels, William D.
Mixtures of two non-absorbing and index-matched materials with contrasting nonlinear optical response have been shown to optically limit above a critical fluence of pulsed nanosecond laser light. Under these conditions, index mismatch is induced between the disparate phases leading to strong Tyndall scattering. The effect has been demonstrated previously by the authors in both solid-liquid mixtures (hexadecane and calcium fluoride), and surfactant-stabilized liquid-liquid emulsions consisting of dichloroethane as the organic phase and a concentrated aqueous phase of sodium thiocyanate (NaSCN). Materials used in these studies exhibit low absorption coefficients over extended wavelength regions allowing for a broadband response of themore » limiter. Recently, limiting has been observed at 532 nm in a polymer composite consisting of barium fluoride and poly-(n-butyl acrylate). A modified open-aperture z-scan method was used to quantify optical limiter performance in this system. Modeling studies provide the basis for designing optical limiters based upon this light scattering mechanism and show the importance of size resonance and constituent optical properties on limiter performance.« less
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Computerized crash reports usability and design investigation : final report.
DOT National Transportation Integrated Search
2016-06-01
Electronic crash reports are advantageous because they can limit missing data, transcription errors, and the space : limitations of a single sheet of paper. Advancing electronic reports through user-centered design affords an : opportunity to improve...
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-12-20
...-Regulatory Organizations; ICE Clear Europe Limited; Notice of Designation of a Longer Period for Commission... October 15, 2012, ICE Clear Europe Limited (``ICE Clear Europe'') filed with the Securities and Exchange...-day time period. \\5\\ 15 U.S.C. 78s(b)(2). The proposed rule change would permit ICE Clear Europe to...
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Code of Federal Regulations, 2013 CFR
2013-10-01
... 45 Public Welfare 4 2013-10-01 2013-10-01 false Is there a limit on the amount of transferred... to Public Welfare (Continued) CORPORATION FOR NATIONAL AND COMMUNITY SERVICE TRANSFER OF EDUCATION AWARDS § 2530.50 Is there a limit on the amount of transferred awards a designated individual may receive...
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Effect of mold designs on molten metal behaviour in high-pressure die casting
NASA Astrophysics Data System (ADS)
Ibrahim, M. D.; Rahman, M. R. A.; Khan, A. A.; Mohamad, M. R.; Suffian, M. S. Z. M.; Yunos, Y. S.; Wong, L. K.; Mohtar, M. Z.
2017-04-01
This paper presents a research study conducted in a local automotive component manufacturer that produces aluminium alloy steering housing local and global markets. This study is to investigate the effect of design modification of mold in die casting as to improve the production rate. Design modification is carried out on the casting shot of the mold. Computer flow simulation was carried out to study the flow of molten metal in the mold with respect to the mold design modification. The design parameters of injection speed, die temperature and clamping force has been included in the study. The result of the simulation showed that modifications of casting shot give significant impact towards the molten flow behaviour in casting process. The capabilities and limitations of die casting process simulation to conduct defect analysis had been optimized. This research will enhance the efficiency of the mass production of the industry of die casting with the understanding of defect analysis, which lies on the modification of the mold design, a way early in its stages of production.
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NASA Astrophysics Data System (ADS)
Saffar, Seha; Azni Jafar, Fairul; Jamaludin, Zamberi
2016-02-01
A case study was selected as a method to collect data in actual industry situation. The study aimed to assess the influences of automated material handling system in automotive industry by proposing a new design of integration system through simulation, and analyze the significant effect and influence of the system. The method approach tool will be CAD Software (Delmia & Quest). The process of preliminary data gathering in phase 1 will collect all data related from actual industry situation. It is expected to produce a guideline and limitation in designing a new integration system later. In phase 2, an idea or concept of design will be done by using 10 principles of design consideration for manufacturing. A full factorial design will be used as design of experiment in order to analyze the performance measured of the integration system with the current system in case study. From the result of the experiment, an ANOVA analysis will be done to study the performance measured. Thus, it is expected that influences can be seen from the improvement made in the system.
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NASA Technical Reports Server (NTRS)
Dorn, H. C.; Wang, J. S.; Glass, T. E.
1986-01-01
This study involves the development of C-13 nuclear resonance as an on-line detector for liquid chromatography (LC-C-13 NMR) for the chemical characterization of aviation fuels. The initial focus of this study was the development of a high sensitivity flow C-13 NMR probe. Since C-13 NMR sensitivity is of paramount concern, considerable effort during the first year was directed at new NMR probe designs. In particular, various toroid coil designs were examined. In addition, corresponding shim coils for correcting the main magnetic field (B sub 0) homogeneity were examined. Based on these initial probe design studies, an LC-C-13 NMR probe was built and flow C-13 NMR data was obtained for a limited number of samples.
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Measuring safety climate in health care.
Flin, R; Burns, C; Mearns, K; Yule, S; Robertson, E M
2006-04-01
To review quantitative studies of safety climate in health care to examine the psychometric properties of the questionnaires designed to measure this construct. A systematic literature review was undertaken to study sample and questionnaire design characteristics (source, no of items, scale type), construct validity (content validity, factor structure and internal reliability, concurrent validity), within group agreement, and level of analysis. Twelve studies were examined. There was a lack of explicit theoretical underpinning for most questionnaires and some instruments did not report standard psychometric criteria. Where this information was available, several questionnaires appeared to have limitations. More consideration should be given to psychometric factors in the design of healthcare safety climate instruments, especially as these are beginning to be used in large scale surveys across healthcare organisations.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Not Available
1994-04-30
As part of the U.S. effort to evaluate technologies offering solutions for the safe disposal or utilization of surplus nuclear materials, the fiscal year 1993 Energy and Water Appropriations legislation provided the Department of Energy (DOE) the necessary funds to conduct multi-phased studies to determine the technical feasibility of using reactor technologies for the triple mission of burning weapons grade plutonium, producing tritium for the existing smaller weapons stockpile, and generating commercial electricity. DOE limited the studies to five advanced reactor designs. Among the technologies selected is the ABB-Combustion Engineering (ABB-CE) System 80+. The DOE study, currently in Phase ID,more » is proceeding with a more detailed evaluation of the design`s capability for plutonium disposition.« less
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Indications and Warning Analysis Management System IWAMS. A Design Study
1980-03-01
First, we must understand the process of warning analysis; we must develop an -;adequate functional model. In the present research we have divided ...and changeable). (In subsequent discussions, considerable attention will be focused on these issues.) -77-7-12Z ’m,77+-U 21 WARNING ANALYSIS MODEL...have charted limitations in man’s memory, attention span, reasoning capability and other cognitive functions. These limitations considerably affect man’s
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Evaluation of agile designs in first-in-human (FIH) trials--a simulation study.
Perlstein, Itay; Bolognese, James A; Krishna, Rajesh; Wagner, John A
2009-12-01
The aim of the investigation was to evaluate alternatives to standard first-in-human (FIH) designs in order to optimize the information gained from such studies by employing novel agile trial designs. Agile designs combine adaptive and flexible elements to enable optimized use of prior information either before and/or during conduct of the study to seamlessly update the study design. A comparison of the traditional 6 + 2 (active + placebo) subjects per cohort design with alternative, reduced sample size, agile designs was performed by using discrete event simulation. Agile designs were evaluated for specific adverse event models and rates as well as dose-proportional, saturated, and steep-accumulation pharmacokinetic profiles. Alternative, reduced sample size (hereafter referred to as agile) designs are proposed for cases where prior knowledge about pharmacokinetics and/or adverse event relationships are available or appropriately assumed. Additionally, preferred alternatives are proposed for a general case when prior knowledge is limited or unavailable. Within the tested conditions and stated assumptions, some agile designs were found to be as efficient as traditional designs. Thus, simulations demonstrated that the agile design is a robust and feasible approach to FIH clinical trials, with no meaningful loss of relevant information, as it relates to PK and AE assumptions. In some circumstances, applying agile designs may decrease the duration and resources required for Phase I studies, increasing the efficiency of early clinical development. We highlight the value and importance of useful prior information when specifying key assumptions related to safety, tolerability, and PK.
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Standardization and program effect analysis (Study 2.4). Volume 3: Design-to-cost analysis
NASA Technical Reports Server (NTRS)
Shiokari, T.
1975-01-01
The program procedures that were incorporated into an on-going "design-to-cost" spacecraft program are examined. Program procedures are the activities that support the development and operations of the flight unit: contract management, documents, integration meetings, engineering, and testing. This report is limited to the program procedures that were implemented, with emphasis on areas that may depart from normal satellite development practices.
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School-Based Service-Learning for Promoting Citizenship in Young People: A Systematic Review
2005-09-06
nonequivalent pre- and post-test design with control group was utilized but participants were not randomized to groups . The sample...other methodology. She notes the limitations of the research chosen for the review (i.e., most studies lack a control group , do not track effects over...experimental and control groups Pre- and post- test design Surveys “Service-learning”12 Intervention groups : Service-learning
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DESIGNING PHASE 0 CANCER CLINICAL TRIALS
Murgo, Anthony J.; Kummar, Shivaani; Rubinstein, Larry; Gutierrez, Martin; Collins, Jerry; Kinders, Robert; Parchment, Ralph E.; Ji, Jiuping; Steinberg, Seth M.; Yang, Sherry X.; Hollingshead, Melinda; Chen, Alice; Helman, Lee; Wiltrout, Robert; Tomaszewski, Joseph E.; Doroshow, James H.
2008-01-01
Phase 0 trials are designed primarily to evaluate the pharmacodynamic and/or pharmacokinetic properties of selected investigational agents prior to initiating more traditional phase 1 testing. One of the major objectives of phase 0 trials is to interrogate and refine a target or biomarker assay for drug effect in human samples implementing procedures developed and validated in preclinical models. Thus, close collaboration between laboratory scientists and clinical investigators is essential to the design and conduct of phase 0 trials. Given the relatively small number of patients and tissue samples, demonstrating a significant drug effect in phase 0 trials requires precise and reproducible assay procedures and innovative statistical methodology. Furthermore, phase 0 trials involving limited exposure of study agent administered at low doses and/or for a short period allows them to be initiated under the FDA Exploratory IND Guidance with less preclinical toxicity data than usually required for traditional first-in-human studies. Because of the very limited drug exposure, phase 0 trials offer no chance of therapeutic benefit, which can impede patient enrollment, particularly if invasive tumor biopsies are required. However, the challenges to accrual are not insurmountable, and well-designed and executed phase 0 trials are feasible and have great potential for improving the efficiency and success of subsequent trials, particularly those evaluating molecularly targeted agents. PMID:18559582
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Nagel, O G; Molina, M P; Basílico, J C; Zapata, M L; Althaus, R L
2009-06-01
To use experimental design techniques and a multiple logistic regression model to optimize a microbiological inhibition test with dichotomous response for the detection of Penicillin G in milk. A 2(3) x 2(2) robust experimental design with two replications was used. The effects of three control factors (V: culture medium volume, S: spore concentration of Geobacillus stearothermophilus, I: indicator concentration), two noise factors (Dt: diffusion time, Ip: incubation period) and their interactions were studied. The V, S, Dt, Ip factors and V x S, V x Ip, S x Ip interactions showed significant effects. The use of 100 microl culture medium volume, 2 x 10(5) spores ml(-1), 60 min diffusion time and 3 h incubation period is recommended. In these elaboration conditions, the penicillin detection limit was of 3.9 microg l(-1), similar to the maximum residue limit (MRL). Of the two noise factors studied, the incubation period can be controlled by means of the culture medium volume and spore concentration. We were able to optimize bioassays of dichotomous response using an experimental design and logistic regression model for the detection of residues at the level of MRL, aiding in the avoidance of health problems in the consumer.
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Design optimization for active twist rotor blades
NASA Astrophysics Data System (ADS)
Mok, Ji Won
This dissertation introduces the process of optimizing active twist rotor blades in the presence of embedded anisotropic piezo-composite actuators. Optimum design of active twist blades is a complex task, since it involves a rich design space with tightly coupled design variables. The study presents the development of an optimization framework for active helicopter rotor blade cross-sectional design. This optimization framework allows for exploring a rich and highly nonlinear design space in order to optimize the active twist rotor blades. Different analytical components are combined in the framework: cross-sectional analysis (UM/VABS), an automated mesh generator, a beam solver (DYMORE), a three-dimensional local strain recovery module, and a gradient based optimizer within MATLAB. Through the mathematical optimization problem, the static twist actuation performance of a blade is maximized while satisfying a series of blade constraints. These constraints are associated with locations of the center of gravity and elastic axis, blade mass per unit span, fundamental rotating blade frequencies, and the blade strength based on local three-dimensional strain fields under worst loading conditions. Through pre-processing, limitations of the proposed process have been studied. When limitations were detected, resolution strategies were proposed. These include mesh overlapping, element distortion, trailing edge tab modeling, electrode modeling and foam implementation of the mesh generator, and the initial point sensibility of the current optimization scheme. Examples demonstrate the effectiveness of this process. Optimization studies were performed on the NASA/Army/MIT ATR blade case. Even though that design was built and shown significant impact in vibration reduction, the proposed optimization process showed that the design could be improved significantly. The second example, based on a model scale of the AH-64D Apache blade, emphasized the capability of this framework to explore the nonlinear design space of complex planform. Especially for this case, detailed design is carried out to make the actual blade manufacturable. The proposed optimization framework is shown to be an effective tool to design high authority active twist blades to reduce vibration in future helicopter rotor blades.
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Quantitative Imaging Biomarkers: A Review of Statistical Methods for Computer Algorithm Comparisons
2014-01-01
Quantitative biomarkers from medical images are becoming important tools for clinical diagnosis, staging, monitoring, treatment planning, and development of new therapies. While there is a rich history of the development of quantitative imaging biomarker (QIB) techniques, little attention has been paid to the validation and comparison of the computer algorithms that implement the QIB measurements. In this paper we provide a framework for QIB algorithm comparisons. We first review and compare various study designs, including designs with the true value (e.g. phantoms, digital reference images, and zero-change studies), designs with a reference standard (e.g. studies testing equivalence with a reference standard), and designs without a reference standard (e.g. agreement studies and studies of algorithm precision). The statistical methods for comparing QIB algorithms are then presented for various study types using both aggregate and disaggregate approaches. We propose a series of steps for establishing the performance of a QIB algorithm, identify limitations in the current statistical literature, and suggest future directions for research. PMID:24919829
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Guidelines for the Design and Conduct of Clinical Studies in Knee Articular Cartilage Repair
Mithoefer, Kai; Saris, Daniel B.F.; Farr, Jack; Kon, Elizaveta; Zaslav, Kenneth; Cole, Brian J.; Ranstam, Jonas; Yao, Jian; Shive, Matthew; Levine, David; Dalemans, Wilfried; Brittberg, Mats
2011-01-01
Objective: To summarize current clinical research practice and develop methodological standards for objective scientific evaluation of knee cartilage repair procedures and products. Design: A comprehensive literature review was performed of high-level original studies providing information relevant for the design of clinical studies on articular cartilage repair in the knee. Analysis of cartilage repair publications and synopses of ongoing trials were used to identify important criteria for the design, reporting, and interpretation of studies in this field. Results: Current literature reflects the methodological limitations of the scientific evidence available for articular cartilage repair. However, clinical trial databases of ongoing trials document a trend suggesting improved study designs and clinical evaluation methodology. Based on the current scientific information and standards of clinical care, detailed methodological recommendations were developed for the statistical study design, patient recruitment, control group considerations, study endpoint definition, documentation of results, use of validated patient-reported outcome instruments, and inclusion and exclusion criteria for the design and conduct of scientifically sound cartilage repair study protocols. A consensus statement among the International Cartilage Repair Society (ICRS) and contributing authors experienced in clinical trial design and implementation was achieved. Conclusions: High-quality clinical research methodology is critical for the optimal evaluation of current and new cartilage repair technologies. In addition to generally applicable principles for orthopedic study design, specific criteria and considerations apply to cartilage repair studies. Systematic application of these criteria and considerations can facilitate study designs that are scientifically rigorous, ethical, practical, and appropriate for the question(s) being addressed in any given cartilage repair research project. PMID:26069574
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A systematic review of sensory-based treatments for children with disabilities.
Barton, Erin E; Reichow, Brian; Schnitz, Alana; Smith, Isaac C; Sherlock, Daniel
2015-02-01
Sensory-based therapies are designed to address sensory processing difficulties by helping to organize and control the regulation of environmental sensory inputs. These treatments are increasingly popular, particularly with children with behavioral and developmental disabilities. However, empirical support for sensory-based treatments is limited. The purpose of this review was to conduct a comprehensive and methodologically sound evaluation of the efficacy of sensory-based treatments for children with disabilities. Methods for this review were registered with PROSPERO (CRD42012003243). Thirty studies involving 856 participants met our inclusion criteria and were included in this review. Considerable heterogeneity was noted across studies in implementation, measurement, and study rigor. The research on sensory-based treatments is limited due to insubstantial treatment outcomes, weak experimental designs, or high risk of bias. Although many people use and advocate for the use of sensory-based treatments and there is a substantial empirical literature on sensory-based treatments for children with disabilities, insufficient evidence exists to support their use. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Barrett, Jeffrey S; Jayaraman, Bhuvana; Patel, Dimple; Skolnik, Jeffrey M
2008-06-01
Previous exploration of oncology study design efficiency has focused on Markov processes alone (probability-based events) without consideration for time dependencies. Barriers to study completion include time delays associated with patient accrual, inevaluability (IE), time to dose limiting toxicities (DLT) and administrative and review time. Discrete event simulation (DES) can incorporate probability-based assignment of DLT and IE frequency, correlated with cohort in the case of DLT, with time-based events defined by stochastic relationships. A SAS-based solution to examine study efficiency metrics and evaluate design modifications that would improve study efficiency is presented. Virtual patients are simulated with attributes defined from prior distributions of relevant patient characteristics. Study population datasets are read into SAS macros which select patients and enroll them into a study based on the specific design criteria if the study is open to enrollment. Waiting times, arrival times and time to study events are also sampled from prior distributions; post-processing of study simulations is provided within the decision macros and compared across designs in a separate post-processing algorithm. This solution is examined via comparison of the standard 3+3 decision rule relative to the "rolling 6" design, a newly proposed enrollment strategy for the phase I pediatric oncology setting.
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Al Mortadi, Noor; Eggbeer, Dominic; Lewis, Jeffrey; Williams, Robert J
2013-04-01
The aim of this study was to analyze the latest innovations in additive manufacture techniques and uniquely apply them to dentistry, to build a sleep apnea device requiring rotating hinges. Laser scanning was used to capture the three-dimensional topography of an upper and lower dental cast. The data sets were imported into an appropriate computer-aided design software environment, which was used to design a sleep apnea device. This design was then exported as a stereolithography file and transferred for three-dimensional printing by an additive manufacture machine. The results not only revealed that the novel computer-based technique presented provides new design opportunities but also highlighted limitations that must be addressed before the techniques can become clinically viable.
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Practical Loop-Shaping Design of Feedback Control Systems
NASA Technical Reports Server (NTRS)
Kopasakis, George
2010-01-01
An improved methodology for designing feedback control systems has been developed based on systematically shaping the loop gain of the system to meet performance requirements such as stability margins, disturbance attenuation, and transient response, while taking into account the actuation system limitations such as actuation rates and range. Loop-shaping for controls design is not new, but past techniques do not directly address how to systematically design the controller to maximize its performance. As a result, classical feedback control systems are designed predominantly using ad hoc control design approaches such as proportional integral derivative (PID), normally satisfied when a workable solution is achieved, without a good understanding of how to maximize the effectiveness of the control design in terms of competing performance requirements, in relation to the limitations of the plant design. The conception of this improved methodology was motivated by challenges in designing control systems of the types needed for supersonic propulsion. But the methodology is generally applicable to any classical control-system design where the transfer function of the plant is known or can be evaluated. In the case of a supersonic aerospace vehicle, a major challenge is to design the system to attenuate anticipated external and internal disturbances, using such actuators as fuel injectors and valves, bypass doors, and ramps, all of which are subject to limitations in actuator response, rates, and ranges. Also, for supersonic vehicles, with long slim type of structures, coupling between the engine and the structural dynamics can produce undesirable effects that could adversely affect vehicle stability and ride quality. In order to design distributed controls that can suppress these potential adverse effects, within the full capabilities of the actuation system, it is important to employ a systematic control design methodology such as this that can maximize the effectiveness of the control design in a methodical and quantifiable way. The emphasis is in generating simple but rather powerful design techniques that will allow even designers with a layman s knowledge in controls to develop effective feedback control designs. Unlike conventional ad hoc methodologies of feedback control design, in this approach actuator rates are incorporated into the design right from the start: The relation between actuator speeds and the desired control bandwidth of the system is established explicitly. The technique developed is demonstrated via design examples in a step-by-step tutorial way. Given the actuation system rates and range limits together with design specifications in terms of stability margins, disturbance rejection, and transient response, the procedure involves designing the feedback loop gain to meet the requirements and maximizing the control system effectiveness, without exceeding the actuation system limits and saturating the controller. Then knowing the plant transfer function, the procedure involves designing the controller so that the controller transfer function together with the plant transfer function equate to the designed loop gain. The technique also shows what the limitations of the controller design are and how to trade competing design requirements such as stability margins and disturbance rejection. Finally, the technique is contrasted against other more familiar control design techniques, like PID control, to show its advantages.
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NanoSat Constellation Mission Design
NASA Technical Reports Server (NTRS)
Concha, Marco; DeFazio, Robert
1998-01-01
The NanoSat constellation concept mission proposes simultaneous operation of multiple swarms of as many as 22 identical 10 kg spacecraft per swarm. The various orbits in a NanoSat swarm vary from 3x12 to 3x42 R(sub e) in geometry. In this report the unique flight dynamics issues of this constellation satellite mission design are addressed. Studies include orbit design, orbit determination, and error analysis. A preliminary survey determined the orbital parameters that would limit the maximum shadow condition while providing adequate ground station access for three ground stations.
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IPAC-Inlet Performance Analysis Code
NASA Technical Reports Server (NTRS)
Barnhart, Paul J.
1997-01-01
A series of analyses have been developed which permit the calculation of the performance of common inlet designs. The methods presented are useful for determining the inlet weight flows, total pressure recovery, and aerodynamic drag coefficients for given inlet geometric designs. Limited geometric input data is required to use this inlet performance prediction methodology. The analyses presented here may also be used to perform inlet preliminary design studies. The calculated inlet performance parameters may be used in subsequent engine cycle analyses or installed engine performance calculations for existing uninstalled engine data.
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NASA transmission research and its probable effects on helicopter transmission design
NASA Technical Reports Server (NTRS)
Zaretsky, E. V.; Coy, J. J.; Townsend, D. P.
1983-01-01
Transmissions studied for application to helicopters in addition to the more conventional geared transmissions include hybrid (traction/gear), bearingless planetary, and split torque transmissions. Research is being performed to establish the validity of analysis and computer codes developed to predict the performance, efficiency, life, and reliability of these transmissions. Results of this research should provide the transmission designer with analytical tools to design for minimum weight and noise with maximum life and efficiency. In addition, the advantages and limitations of drive systems as well as the more conventional systems will be defined.
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NASA transmission research and its probable effects on helicopter transmission design
NASA Technical Reports Server (NTRS)
Zaretsky, E. V.; Coy, J. J.; Townsend, D. P.
1984-01-01
Transmissions studied for application to helicopters in addition to the more conventional geared transmissions include hybrid (traction/gear), bearingless planetary, and split torque transmissions. Research is being performed to establish the validity of analysis and computer codes developed to predict the performance, efficiency, life, and reliability of these transmissions. Results of this research should provide the transmission designer with analytical tools to design for minimum weight and noise with maximum life and efficiency. In addition, the advantages and limitations of drive systems as well as the more conventional systems will be defined.
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Design Methodology for Magnetic Field-Based Soft Tri-Axis Tactile Sensors.
Wang, Hongbo; de Boer, Greg; Kow, Junwai; Alazmani, Ali; Ghajari, Mazdak; Hewson, Robert; Culmer, Peter
2016-08-24
Tactile sensors are essential if robots are to safely interact with the external world and to dexterously manipulate objects. Current tactile sensors have limitations restricting their use, notably being too fragile or having limited performance. Magnetic field-based soft tactile sensors offer a potential improvement, being durable, low cost, accurate and high bandwidth, but they are relatively undeveloped because of the complexities involved in design and calibration. This paper presents a general design methodology for magnetic field-based three-axis soft tactile sensors, enabling researchers to easily develop specific tactile sensors for a variety of applications. All aspects (design, fabrication, calibration and evaluation) of the development of tri-axis soft tactile sensors are presented and discussed. A moving least square approach is used to decouple and convert the magnetic field signal to force output to eliminate non-linearity and cross-talk effects. A case study of a tactile sensor prototype, MagOne, was developed. This achieved a resolution of 1.42 mN in normal force measurement (0.71 mN in shear force), good output repeatability and has a maximum hysteresis error of 3.4%. These results outperform comparable sensors reported previously, highlighting the efficacy of our methodology for sensor design.
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Design Methodology for Magnetic Field-Based Soft Tri-Axis Tactile Sensors
Wang, Hongbo; de Boer, Greg; Kow, Junwai; Alazmani, Ali; Ghajari, Mazdak; Hewson, Robert; Culmer, Peter
2016-01-01
Tactile sensors are essential if robots are to safely interact with the external world and to dexterously manipulate objects. Current tactile sensors have limitations restricting their use, notably being too fragile or having limited performance. Magnetic field-based soft tactile sensors offer a potential improvement, being durable, low cost, accurate and high bandwidth, but they are relatively undeveloped because of the complexities involved in design and calibration. This paper presents a general design methodology for magnetic field-based three-axis soft tactile sensors, enabling researchers to easily develop specific tactile sensors for a variety of applications. All aspects (design, fabrication, calibration and evaluation) of the development of tri-axis soft tactile sensors are presented and discussed. A moving least square approach is used to decouple and convert the magnetic field signal to force output to eliminate non-linearity and cross-talk effects. A case study of a tactile sensor prototype, MagOne, was developed. This achieved a resolution of 1.42 mN in normal force measurement (0.71 mN in shear force), good output repeatability and has a maximum hysteresis error of 3.4%. These results outperform comparable sensors reported previously, highlighting the efficacy of our methodology for sensor design. PMID:27563908
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Design Issues of the Pre-Compression Rings of Iter
NASA Astrophysics Data System (ADS)
Knaster, J.; Baker, W.; Bettinali, L.; Jong, C.; Mallick, K.; Nardi, C.; Rajainmaki, H.; Rossi, P.; Semeraro, L.
2010-04-01
The pre-compression system is the keystone of ITER. A centripetal force of ˜30 MN will be applied at cryogenic conditions on top and bottom of each TF coil. It will prevent the `breathing effect' caused by the bursting forces occurring during plasma operation that would affect the machine design life of 30000 cycles. Different alternatives have been studied throughout the years. There are two major design requirements limiting the engineering possibilities: 1) the limited available space and 2) the need to hamper eddy currents flowing in the structures. Six unidirectionally wound glass-fibre composite rings (˜5 m diameter and ˜300 mm cross section) are the final design choice. The rings will withstand the maximum hoop stresses <500 MPa at room temperature conditions. Although retightening or replacing the pre-compression rings in case of malfunctioning is possible, they have to sustain the load during the entire 20 years of machine operation. The present paper summarizes the pre-compression ring R&D carried out during several years. In particular, we will address the composite choice and mechanical characterization, assessment of creep or stress relaxation phenomena, sub-sized rings testing and the optimal ring fabrication processes that have led to the present final design.
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Optimization of Dynamic Aperture of PEP-X Baseline Design
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Min-Huey; /SLAC; Cai, Yunhai
2010-08-23
SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-{angstrom} x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. Themore » latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.« less
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Closed-loop transfer recovery with observer-based controllers. I - Analysis. II - Design
NASA Technical Reports Server (NTRS)
Chen, Ben M.; Saberi, Ali; Ly, Uy-Loi
1992-01-01
A detailed study is presented of three fundamental issues related to the problem of closed-loop transfer (CLT) recovery. The first issues concerns what can and cannot be achieved for a given system and for an arbitrary target CLT function (TCLTF). The second issue involves developing necessary and/or sufficient conditions for a TCLTF to be recoverable either exactly or approximately. The third issue involves the necessary and/or sufficient conditions on a given system such that it has at least one recoverable TCLTF. The results of the analysis identify some fundamental limitations of the given system as a consequence of its structural properties which enables designers to appreciate at the outset different design limitations incurred in the synthesis of output-feedback controllers. Then, the actual design of full-order or reduced-order observer-based controllers is addressed which will achieve as close as possibly the desired TCLTF. Three design methods are considered: (1) the ATEA method, (2) a method that minimizes the H2-norm of a recovery matrix, and (3) a method that minimizes the respective H(infinity) norm. The relative merits of the methods are discussed.
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Modified Fully Utilized Design (MFUD) Method for Stress and Displacement Constraints
NASA Technical Reports Server (NTRS)
Patnaik, Surya; Gendy, Atef; Berke, Laszlo; Hopkins, Dale
1997-01-01
The traditional fully stressed method performs satisfactorily for stress-limited structural design. When this method is extended to include displacement limitations in addition to stress constraints, it is known as the fully utilized design (FUD). Typically, the FUD produces an overdesign, which is the primary limitation of this otherwise elegant method. We have modified FUD in an attempt to alleviate the limitation. This new method, called the modified fully utilized design (MFUD) method, has been tested successfully on a number of designs that were subjected to multiple loads and had both stress and displacement constraints. The solutions obtained with MFUD compare favorably with the optimum results that can be generated by using nonlinear mathematical programming techniques. The MFUD method appears to have alleviated the overdesign condition and offers the simplicity of a direct, fully stressed type of design method that is distinctly different from optimization and optimality criteria formulations. The MFUD method is being developed for practicing engineers who favor traditional design methods rather than methods based on advanced calculus and nonlinear mathematical programming techniques. The Integrated Force Method (IFM) was found to be the appropriate analysis tool in the development of the MFUD method. In this paper, the MFUD method and its optimality are presented along with a number of illustrative examples.
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Harvesting renewable energy from Earth's mid-infrared emissions.
Byrnes, Steven J; Blanchard, Romain; Capasso, Federico
2014-03-18
It is possible to harvest energy from Earth's thermal infrared emission into outer space. We calculate the thermodynamic limit for the amount of power available, and as a case study, we plot how this limit varies daily and seasonally in a location in Oklahoma. We discuss two possible ways to make such an emissive energy harvester (EEH): A thermal EEH (analogous to solar thermal power generation) and an optoelectronic EEH (analogous to photovoltaic power generation). For the latter, we propose using an infrared-frequency rectifying antenna, and we discuss its operating principles, efficiency limits, system design considerations, and possible technological implementations.
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SwaMURAy - Swapping Memory Unit for Radio Astronomy
NASA Astrophysics Data System (ADS)
Winberg, Simon
2016-03-01
This paper concerns design and performance testing of an HDL module called SwaMURAy that is a configurable, high-speed data sequencing and flow control module serving as an intermediary between data acquisition and subsequent processing stages. While a FIFO suffices for many applications, our case needed a more elaborate solution to overcome legacy design limitations. The SwaMURAy is designed around a system where a block of sampled data is acquired at a fast rate and is then distributed among multiple processing paths to achieve a desired overall processing rate. This architecture provides an effective design pattern around which various software defined radio (SDR) and radio astronomy applications can be built. This solution was partly in response to legacy design restrictions of the SDR platform we used, a difficulty likely experienced by many developers whereby new sampling peripherals are inhibited by legacy characteristics of an underlying reconfigurable platform. Our SDR platform had a planned lifetime of at least five years as a complete redesign and refabrication would be too costly. While the SwaMURAy overcame some performance problems, other problems arose. This paper overviews the SwaMURAy design, performance improvements achieved in an SDR case study, and discusses remaining limitations and workarounds we expect will achieve further improvements.
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Leavy, Justine E; Bull, Fiona C; Rosenberg, Michael; Bauman, Adrian
2011-12-01
Internationally, mass media campaigns to promote regular moderate-intensity physical activity have increased recently. Evidence of mass media campaign effectiveness exists in other health areas, however the evidence for physical activity is limited. The purpose was to systematically review the literature on physical activity mass media campaigns, 2003-2010. A focus was on reviewing evaluation designs, theory used, formative evaluation, campaign effects and outcomes. Literature was searched resulting in 18 individual adult mass media campaigns, mostly in high-income regions and two in middle-income regions. Designs included: quasi experimental (n = 5); non experimental (n = 12); a mixed methods design (n = 1). One half used formative research. Awareness levels ranged from 17 to 95%. Seven campaigns reported significant increases in physical activity levels. The review found that beyond awareness raising, changes in other outcomes were measured, assessed but reported in varying ways. It highlighted improvements in evaluation, although limited evidence of campaign effects remain. It provides an update on the evaluation methodologies used in the adult literature. We recommend optimal evaluation design should include: (1) formative research to inform theories/frameworks, campaign content and evaluation design; (2) cohort study design with multiple data collection points; (3) sufficient duration; (4) use of validated measures; (5) sufficient evaluation resources.
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An information model to support user-centered design of medical devices.
Hagedorn, Thomas J; Krishnamurty, Sundar; Grosse, Ian R
2016-08-01
The process of engineering design requires the product development team to balance the needs and limitations of many stakeholders, including those of the user, regulatory organizations, and the designing institution. This is particularly true in medical device design, where additional consideration must be given for a much more complex user-base that can only be accessed on a limited basis. Given this inherent challenge, few projects exist that consider design domain concepts, such as aspects of a detailed design, a detailed view of various stakeholders and their capabilities, along with the user-needs simultaneously. In this paper, we present a novel information model approach that combines a detailed model of design elements with a model of the design itself, customer requirements, and of the capabilities of the customer themselves. The information model is used to facilitate knowledge capture and automated reasoning across domains with a minimal set of rules by adopting a terminology that treats customer and design specific factors identically, thus enabling straightforward assessments. A uniqueness of this approach is that it systematically provides an integrated perspective on the key usability information that drive design decisions towards more universal or effective outcomes with the very design information impacted by the usability information. This can lead to cost-efficient optimal designs based on a direct inclusion of the needs of customers alongside those of business, marketing, and engineering requirements. Two case studies are presented to show the method's potential as a more effective knowledge management tool with built-in automated inferences that provide design insight, as well as its overall effectiveness as a platform to develop and execute medical device design from a holistic perspective. Copyright © 2016 Elsevier Inc. All rights reserved.
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ERIC Educational Resources Information Center
Hindes, Yvonne L.; Andrews, Jac J. W.
2011-01-01
Twelve empirical studies published since 1996 regarding the effects of gender on the supervisory relationship are reviewed. Each study was reviewed and critiqued in relation to its methodology, research design, critical findings, and limitations. The results of these studies indicate that (a) gender influences the openness and affiliation one…
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Gender Differences in Japanese College Students' Participation in a Qualitative Study
ERIC Educational Resources Information Center
Scott, Douglass J.
2008-01-01
Lincoln and Guba (1985) reminded us that a qualitative study can change midcourse, taking the researcher into areas of inquiry they did not anticipate at the beginning. This case study was originally designed to ascertain the benefits and limitations of video-equipped cellular telephone use by Japanese college students. When the data were…
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Caribbean Regional Communications Service Study. Report.
ERIC Educational Resources Information Center
Lalor, Gerald C.
A follow-up to a limited experiment with the use of satellites in education and public service conducted by the University of the West Indies (UWI) in 1978, this study explores the feasibility of providing a number of services, which would include an extension system based on the use of the UWI telecommunications network. The study was designed to…
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34 CFR 656.30 - What are allowable costs and limitations on allowable costs?
Code of Federal Regulations, 2014 CFR
2014-07-01
... FOREIGN LANGUAGE AND AREA STUDIES OR FOREIGN LANGUAGE AND INTERNATIONAL STUDIES What Conditions Must Be...; and (8) Summer institutes in the United States or abroad designed to provide language and area... study in the subject area on which the Center focuses. (3) Grant funds may not be used to supplant funds...
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34 CFR 656.30 - What are allowable costs and limitations on allowable costs?
Code of Federal Regulations, 2013 CFR
2013-07-01
... FOREIGN LANGUAGE AND AREA STUDIES OR FOREIGN LANGUAGE AND INTERNATIONAL STUDIES What Conditions Must Be...; and (8) Summer institutes in the United States or abroad designed to provide language and area... study in the subject area on which the Center focuses. (3) Grant funds may not be used to supplant funds...
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34 CFR 656.30 - What are allowable costs and limitations on allowable costs?
Code of Federal Regulations, 2012 CFR
2012-07-01
... FOREIGN LANGUAGE AND AREA STUDIES OR FOREIGN LANGUAGE AND INTERNATIONAL STUDIES What Conditions Must Be...; and (8) Summer institutes in the United States or abroad designed to provide language and area... study in the subject area on which the Center focuses. (3) Grant funds may not be used to supplant funds...
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34 CFR 656.30 - What are allowable costs and limitations on allowable costs?
Code of Federal Regulations, 2011 CFR
2011-07-01
... FOREIGN LANGUAGE AND AREA STUDIES OR FOREIGN LANGUAGE AND INTERNATIONAL STUDIES What Conditions Must Be...; and (8) Summer institutes in the United States or abroad designed to provide language and area... study in the subject area on which the Center focuses. (3) Grant funds may not be used to supplant funds...
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Adaptive clinical trial design.
Chow, Shein-Chung
2014-01-01
In recent years, the use of adaptive design methods in clinical trials based on accumulated data at interim has received much attention because of its flexibility and efficiency in pharmaceutical/clinical development. In practice, adaptive design may provide the investigators a second chance to modify or redesign the trial while the study is still ongoing. However, it is a concern that a shift in target patient population may occur after significant adaptations are made. In addition, the overall type I error rate may not be preserved. Moreover, the results may not be reliable and hence are difficult to interpret. As indicated by the US Food and Drug Administration draft guidance on adaptive design clinical trials, the adaptive design has to be a prospectively planned opportunity and should be based on information collected within the study, with or without formal statistical hypothesis testing. This article reviews the relative advantages, limitations, and feasibility of commonly considered adaptive designs in clinical trials. Statistical concerns when implementing adaptive designs are also discussed.
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Benefit design innovations: implications for consumer-directed health care.
Tu, Ha T; Ginsburg, Paul B
2007-02-01
Current health insurance benefit designs that simply rely on higher, one-size-fits-all patient cost sharing have limited potential to curb rapidly rising costs, but innovations in benefit design can potentially make cost sharing a more effective tool, according to a new study by the Center for Studying Health System Change (HSC). Innovative benefit designs include incentives to encourage healthy behaviors; incentives that vary by service type, patient condition or enrollee income; and incentives to use efficient providers. But most applications of these innovative designs are not widespread, suggesting that any significant cost impact is many years off. Moreover, regulations governing high-deductible, consumer-directed health plans eligible for health savings accounts (HSAs) preclude some promising benefit design innovations and dilute the incentives in others. A movement away from a one-size-fits-all HSA benefit structure toward a more flexible design might broaden the appeal of HSA plans and enable them to incorporate features that promote cost-effective care.
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Graphical Tests for Power Comparison of Competing Designs.
Hofmann, H; Follett, L; Majumder, M; Cook, D
2012-12-01
Lineups have been established as tools for visual testing similar to standard statistical inference tests, allowing us to evaluate the validity of graphical findings in an objective manner. In simulation studies lineups have been shown as being efficient: the power of visual tests is comparable to classical tests while being much less stringent in terms of distributional assumptions made. This makes lineups versatile, yet powerful, tools in situations where conditions for regular statistical tests are not or cannot be met. In this paper we introduce lineups as a tool for evaluating the power of competing graphical designs. We highlight some of the theoretical properties and then show results from two studies evaluating competing designs: both studies are designed to go to the limits of our perceptual abilities to highlight differences between designs. We use both accuracy and speed of evaluation as measures of a successful design. The first study compares the choice of coordinate system: polar versus cartesian coordinates. The results show strong support in favor of cartesian coordinates in finding fast and accurate answers to spotting patterns. The second study is aimed at finding shift differences between distributions. Both studies are motivated by data problems that we have recently encountered, and explore using simulated data to evaluate the plot designs under controlled conditions. Amazon Mechanical Turk (MTurk) is used to conduct the studies. The lineups provide an effective mechanism for objectively evaluating plot designs.
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Professional development for design-based learning in engineering education: a case study
NASA Astrophysics Data System (ADS)
Gómez Puente, Sonia M.; van Eijck, Michiel; Jochems, Wim
2015-01-01
Design-based learning (DBL) is an educational approach in which students gather and apply theoretical knowledge to solve design problems. In this study, we examined how critical DBL dimensions (project characteristics, design elements, the teacher's role, assessment, and social context) are applied by teachers in the redesign of DBL projects. We conducted an intervention for the professional development of the DBL teachers in the Mechanical Engineering and the Electrical Engineering departments. We used the Experiential Learning Cycle as an educational model for the professionalisation programme. The findings show that the programme encouraged teachers to apply the DBL theoretical framework. However, there are some limitations with regard to specific project characteristics. Further research into supporting teachers to develop open-ended and multidisciplinary activities in the projects that support learning is recommended.
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Spectral diffraction efficiency characterization of broadband diffractive optical elements.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Choi, Junoh; Cruz-Cabrera, Alvaro Augusto; Tanbakuchi, Anthony
Diffractive optical elements, with their thin profile and unique dispersion properties, have been studied and utilized in a number of optical systems, often yielding smaller and lighter systems. Despite the interest in and study of diffractive elements, the application has been limited to narrow spectral bands. This is due to the etch depths, which are optimized for optical path differences of only a single wavelength, consequently leading to rapid decline in efficiency as the working wavelength shifts away from the design wavelength. Various broadband diffractive design methodologies have recently been developed that improve spectral diffraction efficiency and expand the workingmore » bandwidth of diffractive elements. We have developed diffraction efficiency models and utilized the models to design, fabricate, and test two such extended bandwidth diffractive designs.« less