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Sample records for perspectives structural problems

  1. Alternative Perspectives on Risk: Individual Differences in Problem Structuring

    NASA Technical Reports Server (NTRS)

    Orasanu, Judith; Fischer, Ute; Connors, Mary M. (Technical Monitor)

    1997-01-01

    Team decision making involves contributions of multiple players toward a common goal. While much has been written about the importance of developing shared mental models in order for teams to work together effectively, little has been done to determine the value of alternative perspectives on problem solving and decision making. Early studies of expertise contrasted experts with novices and noted that the two groups differ in the way they structure problems and in their selection of information as salient. Little attention has been given to differences among experts who differ in their specializations. A series of experiments was conducted to determine: (1) what dimensions of flight-related problem situations pilots judge to be most important when making flight-relevant decisions; and (2) whether pilots in different crew positions differ in the way they interpret problems relating to flight decisions. A sorting task was used to identify underlying dimensions judged as salient to individual pilots. Captains, first officers, and flight engineers from two major carriers participated in the study. Twenty-two flight scenarios were developed based on ASRS reports. Pilots were required to make judgments about how they would respond in each case and to sort the scenarios on the basis of similarity of decision factors. They were also asked to provide a verbal label that described each of their sorted categories. A second study required a different group of pilots (also captains, first officers and flight engineers) to sort on predetermined bases.

  2. Algorithmic Perspectives on Problem Formulations in MDO

    NASA Technical Reports Server (NTRS)

    Alexandrov, Natalia M.; Lewis, Robert Michael

    2000-01-01

    This work is concerned with an approach to formulating the multidisciplinary optimization (MDO) problem that reflects an algorithmic perspective on MDO problem solution. The algorithmic perspective focuses on formulating the problem in light of the abilities and inabilities of optimization algorithms, so that the resulting nonlinear programming problem can be solved reliably and efficiently by conventional optimization techniques. We propose a modular approach to formulating MDO problems that takes advantage of the problem structure, maximizes the autonomy of implementation, and allows for multiple easily interchangeable problem statements to be used depending on the available resources and the characteristics of the application problem.

  3. Comparing Multiple Solutions in the Structured Problem Solving: Deconstructing Japanese Lessons from Learner's Perspective

    ERIC Educational Resources Information Center

    Hino, Keiko

    2015-01-01

    The purpose of this study is to enhance our understanding of how students listen and attend to multiple solutions proposed by their classmates during the activity of comparison. This study examines ten consecutive lessons in each of the two eighth-grade classrooms in Tokyo that are organized in the style of "structured problem solving".…

  4. YOUTH EDUCATION, PROBLEMS, PERSPECTIVES, PROMISES.

    ERIC Educational Resources Information Center

    MUESSIG, RAYMOND H.

    IN AN ANALYSIS OF CONTEMPORARY ADOLESCENT EDUCATION BY SEVEN MEMBERS OF A YEARBOOK COMMITTEE, FIVE PERSPECTIVES--SOCIAL-PHILOSOPHICAL, PSYCHOPHYSICAL, LITERARY, CURRICULAR, AND METHODOLOGICAL--ARE CONSIDERED, AND CONSTRUCTIVE PROPOSALS FOR SOLVING RELATED PROBLEMS ARE SUGGESTED. AN INTRODUCTORY CHAPTER DISCUSSES THE BASIC TEEN-AGE PROBLEM AREAS OF…

  5. Problem-Framing: A perspective on environmental problem-solving

    NASA Astrophysics Data System (ADS)

    Bardwell, Lisa V.

    1991-09-01

    The specter of environmental calamity calls for the best efforts of an involved public. Ironically, the way people understand the issues all too often serves to discourage and frustrate rather than motivate them to action. This article draws from problem-solving perspectives offered by cognitive psychology and conflict management to examine a framework for thinking about environmental problems that promises to help rather than hinder efforts to address them. Problem-framing emphasizes focusing on the problem definition. Since how one defines a problem determines one's understanding of and approach to that problem, being able to redefine or reframe a problem and to explore the “problem space” can help broaden the range of alternatives and solutions examined. Problem-framing incorporates a cognitive perspective on how people respond to information. It explains why an emphasis on problem definition is not part of people's typical approach to problems. It recognizes the importance of structure and of having ways to organize that information on one's problem-solving effort. Finally, problem-framing draws on both cognitive psychology and conflict management for strategies to manage information and to create a problem-solving environment that not only encourages participation but can yield better approaches to our environmental problems.

  6. Perspectives on Problem Solving and Instruction

    ERIC Educational Resources Information Center

    van Merrienboer, Jeroen J. G.

    2013-01-01

    Most educators claim that problem solving is important, but they take very different perspective on it and there is little agreement on how it should be taught. This article aims to sort out the different perspectives and discusses problem solving as a goal, a method, and a skill. As a goal, problem solving should not be limited to well-structured…

  7. Theoretical and Philosophical Perspectives to Problem Solving.

    ERIC Educational Resources Information Center

    Sherman, Thomas M.; And Others

    1988-01-01

    Five articles explore various theoretical aspects of problems and problem solving skills. Highlights include strategies to learn problem solving skills; knowledge structures; metacognition; behavioral processes and cognitive psychology; erotetic logic; creativity as an aspect of computer problem solving; and programing as a problem-solving…

  8. [Addiction therapy. Limits, problems, perspectives].

    PubMed

    Kalapos, Miklós Péter

    2014-01-01

    In health care, tending is a process, which offers for the patients a continuous watching on, a control, a treatment, and the prevention of worsening of their medical status as well as the reduction of their complaints. In the article, some fundamental segments of tending in addictology are reviewed, particularly paying attention to whom, how, where and how long to take care. On the basis of literature, the author stresses whatever method is used to treat addict patients it is more beneficial to society than the avoidance of any intervention due to the negligence of the problem. Addictology has lost a lot from its power in Hungary. The author recommends the introduction of the methods of health quality assurance to decrease the effect of negative trends seen in addictology. The paper also deals with special patient groups including homeless clients, adolescents, elderly and pregnant patients as well as health care professionals. The author critically mentions the double communication of society, the dual-face character of politics and has the opinion that competences are not clear making the situation confused. As a mistake of the point of view is it regarded that the addictological problems are classified as to belonging to the authority of psychiatry. It is emphasized that multidisciplinary approach is needed to understand the problem and to treat the client. General screening for addictological diseases does not seem possible in the light of low capacity of the system, but the screening of adolescents and pregnant women is definitely recommended. And finally, a financial support for medicines to prevent craving, a moratorium for the continuous changing of rules and law, the sponsoring of harm reduction programs as well as a better utilization of opportunities offered by local drug coordinating boards are proposed. PMID:25411227

  9. Food sustainability: problems, perspectives and solutions.

    PubMed

    Garnett, Tara

    2013-02-01

    The global food system makes a significant contribution to climate changing greenhouse gas emissions with all stages in the supply chain, from agricultural production through processing, distribution, retailing, home food preparation and waste, playing a part. It also gives rise to other major environmental impacts, including biodiversity loss and water extraction and pollution. Policy makers are increasingly aware of the need to address these concerns, but at the same time they are faced with a growing burden of food security and nutrition-related problems, and tasked with ensuring that there is enough food to meet the needs of a growing global population. In short, more people need to be fed better, with less environmental impact. How might this be achieved? Broadly, three main 'takes' or perspectives, on the issues and their interactions, appear to be emerging. Depending on one's view point, the problem can be conceptualised as a production challenge, in which case there is a need to change how food is produced by improving the unit efficiency of food production; a consumption challenge, which requires changes to the dietary drivers that determine food production; or a socio-economic challenge, which requires changes in how the food system is governed. This paper considers these perspectives in turn, their implications for nutrition and climate change, and their strengths and weaknesses. Finally, an argument is made for a reorientation of policy thinking which uses the insights provided by all three perspectives, rather than, as is the situation today, privileging one over the other. PMID:23336559

  10. Individual therapy for couple problems: perspectives and pitfalls.

    PubMed

    Gurman, Alan S; Burton, Mark

    2014-10-01

    Despite the demonstrated efficacy of conjoint couple therapy, many clients seeking help for couple problems ultimately find themselves in individual therapy for these concerns. Individual therapy for couple problems (ITCP) may evolve from a partner's refusal of conjoint therapy or from the treatment format preferences of either the client or therapist. Having acknowledged the role of partner refusals, we offer some perspectives about the idiosyncratic personal factors and professional background factors that may lead therapists to provide ITCP and discuss the significant pitfalls in its practice. We emphasize five central areas of concern in the ongoing practice of ITCP: structural constraints on change; therapist side-taking and the therapeutic alliance; inaccurate assessments based on individual client reports; therapeutic focus; and ethical issues relevant to both attending and nonattending partners. We conclude by urging that this very important but largely neglected topic be paid greater attention in psychotherapy research, training and continuing education. PMID:24773422

  11. A Set-Oriented Perspective on Solving Counting Problems

    ERIC Educational Resources Information Center

    Lockwood, Elise

    2014-01-01

    In this article, I present the notion of a set-oriented perspective for solving counting problems that emerged during task-based interviews with postsecondary students. Framing the findings within Harel's "ways of thinking", I argue that students may benefit from this perspective, in which they view attending to sets of outcomes as…

  12. Affect and Problem Solving: Two Theoretical Perspectives.

    ERIC Educational Resources Information Center

    McLeod, Douglas B.

    Cognitive factors related to problem solving have been explored, but affective factors also play an important role in the teaching of mathematical problem solving. This paper outlines the theories of George Mandler and Bernard Weiner, providing a useful background for research related to affect and problem solving. Data related to the two theories…

  13. Dynamic Problem Solving: A New Assessment Perspective

    ERIC Educational Resources Information Center

    Greiff, Samuel; Wustenberg, Sascha; Funke, Joachim

    2012-01-01

    This article addresses two unsolved measurement issues in dynamic problem solving (DPS) research: (a) unsystematic construction of DPS tests making a comparison of results obtained in different studies difficult and (b) use of time-intensive single tasks leading to severe reliability problems. To solve these issues, the MicroDYN approach is…

  14. Rio Grande rift: problems and perspectives

    SciTech Connect

    Baldridge, W.S.; Olsen, K.H.; Callender, J.F.

    1984-01-01

    Topics and ideas addressed include: (1) the regional extent of the Rio Grande rift; (2) the structure of the crust and upper mantle; (3) whether the evidence for an axile dike in the lower crust is compelling; (4) the nature of faulting and extension in the crust; and (5) the structural and magmatic development of the rift. 88 references, 5 figures.

  15. PREFACE: The random search problem: trends and perspectives The random search problem: trends and perspectives

    NASA Astrophysics Data System (ADS)

    da Luz, Marcos G. E.; Grosberg, Alexander; Raposo, Ernesto P.; Viswanathan, Gandhi M.

    2009-10-01

    very important to solve computationally complex problems (e.g., protein folding), which involve optimizations in very high dimensional energy landscapes. On the other hand, random searches can also be studied from the perspective of diffusion and transport properties which is an important topic in condensed matter and statistical physics. For instance, the features of light scattered in a media, where the scatterers have a power-law distribution of sizes in many aspects, may resemble the patterns generated by a searcher performing Lévy walks. There are many questions related to random searches: how the searcher moves or should move, what are the patterns generated during the locomotion, how do the encounter rates depend on parameters of the search, etc. But perhaps, the most well known issue is how to optimize the search for specific target scenarios. The optimization can be in either continuous or discrete environments, when the information available is limited. The answer to this question determines specific strategies of movement that would maximize some properly defined search efficiency measure. The relevance of the question stems from the fact that the strategy-dynamics represents one of the most important factors that modulate the rate of encounters (e.g., the encounter rate between predator and prey). In the general context, strategy choices can be essential in determining the outcome and thus the success of a given search. For instance, realistic searches—and locomotion in general—require the expenditure of energy. Thus, inefficient search could deplete energy reserves (e.g., fat) and lead to rates of encounters below a minimum acceptable threshold (resulting in extinction of a species, for example). The framework of the random search `game' distinguishes between the two interacting players in a context of pursuit and chance. They are either a `searcher' (e.g., predator, protein, radar, `crawler') or a `target' (e.g., prey, DNA sequence, a missing

  16. A geometrical perspective for the bargaining problem.

    PubMed

    Wong, Kelvin Kian Loong

    2010-01-01

    A new treatment to determine the Pareto-optimal outcome for a non-zero-sum game is presented. An equilibrium point for any game is defined here as a set of strategy choices for the players, such that no change in the choice of any single player will increase the overall payoff of all the players. Determining equilibrium for multi-player games is a complex problem. An intuitive conceptual tool for reducing the complexity, via the idea of spatially representing strategy options in the bargaining problem is proposed. Based on this geometry, an equilibrium condition is established such that the product of their gains over what each receives is maximal. The geometrical analysis of a cooperative bargaining game provides an example for solving multi-player and non-zero-sum games efficiently. PMID:20436675

  17. Solving Math Problems Approximately: A Developmental Perspective

    PubMed Central

    Ganor-Stern, Dana

    2016-01-01

    Although solving arithmetic problems approximately is an important skill in everyday life, little is known about the development of this skill. Past research has shown that when children are asked to solve multi-digit multiplication problems approximately, they provide estimates that are often very far from the exact answer. This is unfortunate as computation estimation is needed in many circumstances in daily life. The present study examined 4th graders, 6th graders and adults’ ability to estimate the results of arithmetic problems relative to a reference number. A developmental pattern was observed in accuracy, speed and strategy use. With age there was a general increase in speed, and an increase in accuracy mainly for trials in which the reference number was close to the exact answer. The children tended to use the sense of magnitude strategy, which does not involve any calculation but relies mainly on an intuitive coarse sense of magnitude, while the adults used the approximated calculation strategy which involves rounding and multiplication procedures, and relies to a greater extent on calculation skills and working memory resources. Importantly, the children were less accurate than the adults, but were well above chance level. In all age groups performance was enhanced when the reference number was smaller (vs. larger) than the exact answer and when it was far (vs. close) from it, suggesting the involvement of an approximate number system. The results suggest the existence of an intuitive sense of magnitude for the results of arithmetic problems that might help children and even adults with difficulties in math. The present findings are discussed in the context of past research reporting poor estimation skills among children, and the conditions that might allow using children estimation skills in an effective manner. PMID:27171224

  18. Nigeria's internal petroleum problems: perspectives and choices

    SciTech Connect

    Iwayemi, A.

    1984-10-01

    Oil-producing Nigeria has been hard hit by weakening oil markets, the replacement of the civilian government by a military regime, and sporadic but severe energy supply problems. The latter included shortages of petroleum products and irregular availability of electricity. These conditions will worsen unless Nigeria takes immediate action to introduce demand management, including efficient pricing and other conservation measures, and timely investment to expand domestic energy facilities, change the institutional and policy environment, and assure the availability of imported supplies. It is also important to encourage the development of renewable energy sources. 16 references, 2 tables.

  19. Biography for Children: A Summary of Problems and Perspectives.

    ERIC Educational Resources Information Center

    Jurich, Marilyn

    This article summarizes some of the problems of and perspectives on biography for children. The major categories include: "Predominant Defects in Biographies for Younger Children," which discusses unprobed statements, oversimplified explanations leading to false ideas, the omission of "necessary" violence, the infallibility of the hero, the need…

  20. Carbapenem resistance: overview of the problem and future perspectives

    PubMed Central

    2016-01-01

    Carbapenem resistance, mainly among Gram-negative pathogens, is an ongoing public-health problem of global dimensions. This type of antimicrobial resistance, especially when mediated by transferable carbapenemase-encoding genes, is spreading rapidly causing serious outbreaks and dramatically limiting treatment options. In this article, important key points related to carbapenem resistance are reviewed and future perspectives are discussed. PMID:26862399

  1. Teacher Perspectives on Peer Relation Problems of Young Children.

    ERIC Educational Resources Information Center

    Moon, Mugyeong

    2001-01-01

    Qualitative study involving 3 teachers' perspectives of peer relationship problems of 24-year-old children in a university-affiliated preschool. Teachers used three criteria to judge peer relationships: Children's emotional well-being, motivation behind social behavior, and social skills. Finds children's efforts to control peers to be the most…

  2. [Problems and perspectives of occupational carcinogenesis].

    PubMed

    Merletti, F; Vineis, P; Bertazzi, P A

    1991-01-01

    Epidemiologic research has played an important role in identifying and confirming the carcinogenicity of chemicals. This was facilitated in the past by the high levels of exposure and by the simple correspondence between one exposure and one or few job titles. Today we are faced with a different picture: workers are exposed to complex mixtures, exposure levels have decreased while mobility of the work-force has increased. In this changing context, epidemiology needs new methodological tools to improve the validity of risk assessment. The most promising of these seem to be the new techniques of biochemical epidemiology and the development of job-exposure matrices. Among the more traditional tools, record-linkage studies may be relevant in identifying long-term occupational hazards. The methodological problems and the ethical and operative implications of these trends in research are discussed. PMID:1758341

  3. [Mortality statistics in Germany. Problems and perspectives].

    PubMed

    Schelhase, T; Weber, S

    2007-07-01

    The causes of death statistics is widely used as a major source of data for monitoring particular health indicators and their change over time. Results of these comparisons are used for epidemiologic and medical research and as a starting point to give recommendations for prevention programs and for health policy. Nevertheless, the quality of the causes of death statistics is often criticized. Beside the quality of the medical information the critic aims in particular at the restricted comparability of the data and the limitation of the statistics on mono-causal causes of death. The latter aspects refer to steps which are performed within the scope of the data processing in the statistical offices. With the introduction of an automated coding system, which is able to code all causes of deaths on the death certificate and select the underlying cause of death automatically, it will be possible to solve these problems. Furthermore the automated coding system is the prerequisite for a routine multiple-cause coding which is demanded by several medical and statistical experts. PMID:17581726

  4. [Aquaculture in the Netherlands: problems and perspectives].

    PubMed

    Hogendoorn, H

    1986-11-15

    New interest is being focussed on the more than 100-year-old field of fish culture in the Netherlands. The systems of production available show varying degrees of control of the fish and their environment, and they have a corresponding yield: 0.01-250 kg/m3/year. The recently developed recirculation systems (40-80 kg/m3) make possible the commercial production of luxury species of fish, independently of climatological conditions and having minimum effects on the environment. Some technical aspects of reproduction, housing, nutrition, growth, health control and marketing of the fish require further attention. But the absence of a solid tradition of fish culture is the main problem in the development of fish culture in the Netherlands today. Good fish stockmanship is required at farmers' level. And the organisation and governmental support, that turned agriculture into a highly successful industry, are also essential. For the moment, the most promising commercial prospects are provided by a number of luxury fish species: trout, salmon, eel, sole, turbot, tilapia, catfish, seabass and seabream. A joint effort may help to overcome the remaining technical and logistical uncertainties. PMID:3798438

  5. Problems of Teaching the Behaviorist Perspective in the Cognitive Revolution

    PubMed Central

    Abramson, Charles I.

    2013-01-01

    This article offers some personal reflections on the difficulty of teaching the behaviorist perspective in the psychology classroom. The problems focus on the inadequacy of introductory textbooks—which mischaracterize behaviorism, only present the most extreme behaviorist positions, make no mention of the neobehaviorist perspective, fail to discuss that there is no accepted criteria for determining what type of behavior is cognitive, and provide a definition of cognition that is, not only inconsistent across texts, but so broad as to overshadow the behaviorist contributions. Suggestions are provided for instructors on how to present to their students an accurate portrayal of behaviorism. PMID:25379226

  6. PREFACE: The random search problem: trends and perspectives The random search problem: trends and perspectives

    NASA Astrophysics Data System (ADS)

    da Luz, Marcos G. E.; Grosberg, Alexander; Raposo, Ernesto P.; Viswanathan, Gandhi M.

    2009-10-01

    very important to solve computationally complex problems (e.g., protein folding), which involve optimizations in very high dimensional energy landscapes. On the other hand, random searches can also be studied from the perspective of diffusion and transport properties which is an important topic in condensed matter and statistical physics. For instance, the features of light scattered in a media, where the scatterers have a power-law distribution of sizes in many aspects, may resemble the patterns generated by a searcher performing Lévy walks. There are many questions related to random searches: how the searcher moves or should move, what are the patterns generated during the locomotion, how do the encounter rates depend on parameters of the search, etc. But perhaps, the most well known issue is how to optimize the search for specific target scenarios. The optimization can be in either continuous or discrete environments, when the information available is limited. The answer to this question determines specific strategies of movement that would maximize some properly defined search efficiency measure. The relevance of the question stems from the fact that the strategy-dynamics represents one of the most important factors that modulate the rate of encounters (e.g., the encounter rate between predator and prey). In the general context, strategy choices can be essential in determining the outcome and thus the success of a given search. For instance, realistic searches—and locomotion in general—require the expenditure of energy. Thus, inefficient search could deplete energy reserves (e.g., fat) and lead to rates of encounters below a minimum acceptable threshold (resulting in extinction of a species, for example). The framework of the random search `game' distinguishes between the two interacting players in a context of pursuit and chance. They are either a `searcher' (e.g., predator, protein, radar, `crawler') or a `target' (e.g., prey, DNA sequence, a missing

  7. Random generation of structured linear optimization problems

    SciTech Connect

    Arthur, J.; Frendewey, J. Jr.

    1994-12-31

    We describe the on-going development of a random generator for linear optimization problems (LPs) founded on the concept of block structure. The general LP: minimize z = cx subject to Ax = b, x {ge} 0 can take a variety of special forms determined (primarily) by predefined structures on the matrix A of constraint coefficients. The authors have developed several random problem generators which provide instances of LPs having such structure; in particular (i) general (non-structured) problems, (ii) generalized upper bound (GUB) constraints, (iii) minimum cost network flow problems, (iv) transportation and assignment problems, (v) shortest path problems, (vi) generalized network flow problems, and (vii) multicommodity network flow problems. This paper discusses the general philosophy behind the construction of these generators. In addition, the task of combining the generators into a single generator -- in which the matrix A can contain various blocks, each of a prescribed structure from those mentioned above -- is described.

  8. Three P's in Cosmology: Progress, Problems, and Perspectives

    NASA Astrophysics Data System (ADS)

    Dolgov, A. D.

    2014-04-01

    A review on the development of cosmology for a diverse audience is presented. The first historical part is devoted to the works done half a century ago with an emphasize to those performed in Russia (or more precisely, in the Soviet Union). Then the recent data on the cosmic microwave background raditation is discussed and the impact of these data on the neutrino mass and the number of neutrino species is considered. The latter is compared with the results obtained from the big bang nucleosynthesis. Next, a short description and history of the cosmological inflation is presented. The basics of the standard cosmological model and the problems of dark matter and dark energy are considered at the end of the fist section entitled "Progress". In the next short section, "Problems", one can find a list of the unsolved cosmological and astrophysical problems, which is by no means fully comprehensive. The last supershort section contains a few words about the perspectives of future development.

  9. Trinucleotide Repeats: A Structural Perspective

    PubMed Central

    Almeida, Bruno; Fernandes, Sara; Abreu, Isabel A.; Macedo-Ribeiro, Sandra

    2013-01-01

    Trinucleotide repeat (TNR) expansions are present in a wide range of genes involved in several neurological disorders, being directly involved in the molecular mechanisms underlying pathogenesis through modulation of gene expression and/or the function of the RNA or protein it encodes. Structural and functional information on the role of TNR sequences in RNA and protein is crucial to understand the effect of TNR expansions in neurodegeneration. Therefore, this review intends to provide to the reader a structural and functional view of TNR and encoded homopeptide expansions, with a particular emphasis on polyQ expansions and its role at inducing the self-assembly, aggregation and functional alterations of the carrier protein, which culminates in neuronal toxicity and cell death. Detail will be given to the Machado-Joseph Disease-causative and polyQ-containing protein, ataxin-3, providing clues for the impact of polyQ expansion and its flanking regions in the modulation of ataxin-3 molecular interactions, function, and aggregation. PMID:23801983

  10. Structural Perspective on Enzymatic Halogenation

    PubMed Central

    2008-01-01

    Simple halogen substituents frequently afford key structural features that account for the potency and selectivity of natural products, including antibiotics and hormones. For example, when a single chlorine atom on the antibiotic vancomycin is replaced by hydrogen, the resulting antibacterial activity decreases by up to 70% (HarrisC. M.; KannanR.; KopeckaH.; HarrisT. M.J. Am. Chem. Soc.1985, 107, 6652−6658). This Account analyzes how structure underlies mechanism in halogenases, the molecular machines designed by nature to incorporate halogens into diverse substrates. Traditional synthetic methods of integrating halogens into complex molecules are often complicated by a lack of specificity and regioselectivity. Nature, however, has developed a variety of elegant mechanisms for halogenating specific substrates with both regio- and stereoselectivity. An improved understanding of the biological routes toward halogenation could lead to the development of novel synthetic methods for the creation of new compounds with enhanced functions. Already, researchers have co-opted a fluorinase from the microorganism Streptomyces cattleya to produce 18F-labeled molecules for use in positron emission tomography (PET) (DengH.; CobbS. L.; GeeA. D.; LockhartA.; MartarelloL.; McGlincheyR. P.; O’HaganD.; OnegaM.Chem. Commun.2006, 652−654). Therefore, the discovery and characterization of naturally occurring enzymatic halogenation mechanisms has become an active area of research. The catalogue of known halogenating enzymes has expanded from the familiar haloperoxidases to include oxygen-dependent enzymes and fluorinases. Recently, the discovery of a nucleophilic halogenase that catalyzes chlorinations has expanded the repertoire of biological halogenation chemistry (DongC.; HuangF.; DengH.; SchaffrathC.; SpencerJ. B.; O’HaganD.; NaismithJ. H.Nature2004, 427, 561−56514765200). Structural characterization has provided a basis toward a mechanistic understanding of the specificity

  11. Organizational Structure and Complex Problem Solving

    ERIC Educational Resources Information Center

    Becker, Selwyn W.; Baloff, Nicholas

    1969-01-01

    The problem-solving efficiency of different organization structures is discussed in relation to task requirements and the appropriate organizational behavior, to group adaptation to a task over time, and to various group characteristics. (LN)

  12. Perceived organizational problems in health care: a pilot test of the structured problem and success inventory.

    PubMed

    Nyström, Monica E; Terris, Darcey D; Sparring, Vibeke; Tolf, Sara; Brown, Claire R

    2012-01-01

    Our objective was to test whether the Structured Problem and Success Inventory (SPI) instrument could capture mental representations of organizational and work-related problems as described by individuals working in health care organizations and to test whether these representations varied according to organizational position. A convenience sample (n = 56) of middle managers (n = 20), lower-level managers (n = 20), and staff (n = 16) from health care organizations in Stockholm (Sweden) attending organizational development courses during 2003-2004 was recruited. Participants used the SPI to describe the 3 most pressing organizational and work-related problems. Data were systematically reviewed to identify problem categories and themes. One hundred sixty-four problems were described, clustered into 13 problem categories. Generally, middle managers focused on organizational factors and managerial responsibilities, whereas lower-level managers and staff focused on operational issues and what others did or ought to do. Furthermore, we observed similarities and variation in perceptions and their association with respondents' position within an organization. Our results support the need for further evaluation of the SPI as a promising tool for health care organizations. Collecting structured inventories of organizational and work-related problems from multiple perspectives may assist in the development of shared understandings of organizational challenges and lead to more effective and efficient processes of solution planning and implementation. PMID:22453820

  13. A combinatorial perspective of the protein inference problem.

    PubMed

    Yang, Chao; He, Zengyou; Yu, Weichuan

    2013-01-01

    In a shotgun proteomics experiment, proteins are the most biologically meaningful output. The success of proteomics studies depends on the ability to accurately and efficiently identify proteins. Many methods have been proposed to facilitate the identification of proteins from peptide identification results. However, the relationship between protein identification and peptide identification has not been thoroughly explained before. In this paper, we devote ourselves to a combinatorial perspective of the protein inference problem. We employ combinatorial mathematics to calculate the conditional protein probabilities (protein probability means the probability that a protein is correctly identified) under three assumptions, which lead to a lower bound, an upper bound, and an empirical estimation of protein probabilities, respectively. The combinatorial perspective enables us to obtain an analytical expression for protein inference. Our method achieves comparable results with ProteinProphet in a more efficient manner in experiments on two data sets of standard protein mixtures and two data sets of real samples. Based on our model, we study the impact of unique peptides and degenerate peptides (degenerate peptides are peptides shared by at least two proteins) on protein probabilities. Meanwhile, we also study the relationship between our model and ProteinProphet. We name our program ProteinInfer. Its Java source code, our supplementary document and experimental results are available at: >http://bioinformatics.ust.hk/proteininfer. PMID:24407311

  14. High Density Electroencephalography in Sleep Research: Potential, Problems, Future Perspective

    PubMed Central

    Lustenberger, Caroline; Huber, Reto

    2012-01-01

    High density EEG (hdEEG) during sleep combines the superior temporal resolution of EEG recordings with high spatial resolution. Thus, this method allows a topographical analysis of sleep EEG activity and thereby fosters the shift from a global view of sleep to a local one. HdEEG allowed to investigate sleep rhythms in terms of their characteristic behavior (e.g., the traveling of slow waves) and in terms of their relationship to cortical functioning (e.g., consciousness and cognitive abilities). Moreover, recent studies successfully demonstrated that hdEEG can be used to study brain functioning in neurological and neuro-developmental disorders, and to evaluate therapeutic approaches. This review highlights the potential, the problems, and future perspective of hdEEG in sleep research. PMID:22593753

  15. Structural damage assessment as an identification problem

    NASA Technical Reports Server (NTRS)

    Hajela, Prabhat; Soeiro, F. J.

    1989-01-01

    Damage assessment of structural assemblies is treated as an identification problem. A brief review of identification methods is first presented with particular focus on the output error approach. The use of numerical optimization methods in identifying the location and extent of damage in structures is studied. The influence of damage on eigenmode shapes and static displacements is explored as a means of formulating a measure of damage in the structure. Preliminary results obtained in this study are presented and special attention is directed at the shortcomings associated with the nonlinear programming approach to solving the optimization problem.

  16. Problems of Higher Education in India. An Approach to Structural Analysis and Reorganization.

    ERIC Educational Resources Information Center

    Joshi, K. L.

    Problems facing higher education in India are examined in terms of systems analysis, structural changes, input-output ratios, and critical perspectives of the system itself. Part I (Introduction and Present Position) provides an introduction to the problems, information on the education commission, and planning in education. Part II (Higher…

  17. Structural and Linguistic Variables in Problem Solving.

    ERIC Educational Resources Information Center

    Jerman, Max; Mirman, Sanford

    This paper reports on an experiment designed to investigate the effect of structural and linguistic variables on level of difficulty in solving arithmetic word problems. Identification of such variables is intended to assist curriculum writers in preparing exercises at a specified level of difficulty for students at various age levels. The study…

  18. Structured eigenvalue problems for rational gauss quadrature

    NASA Astrophysics Data System (ADS)

    Fasino, Dario; Gemignani, Luca

    2007-08-01

    The connection between Gauss quadrature rules and the algebraic eigenvalue problem for a Jacobi matrix was first exploited in the now classical paper by Golub and Welsch (Math. Comput. 23(106), 221?230, 1969). From then on many computational problems arising in the construction of (polynomial) Gauss quadrature formulas have been reduced to solving direct and inverse eigenvalue problems for symmetric tridiagonals. Over the last few years (rational) generalizations of the classical Gauss quadrature formulas have been studied, i.e., formulas integrating exactly in spaces of rational functions. This paper wants to illustrate that stable and efficient procedures based on structured numerical linear algebra techniques can also be devised for the solution of the eigenvalue problems arising in the field of rational Gauss quadrature.

  19. Unifying Temporal and Structural Credit Assignment Problems

    NASA Technical Reports Server (NTRS)

    Agogino, Adrian K.; Tumer, Kagan

    2004-01-01

    Single-agent reinforcement learners in time-extended domains and multi-agent systems share a common dilemma known as the credit assignment problem. Multi-agent systems have the structural credit assignment problem of determining the contributions of a particular agent to a common task. Instead, time-extended single-agent systems have the temporal credit assignment problem of determining the contribution of a particular action to the quality of the full sequence of actions. Traditionally these two problems are considered different and are handled in separate ways. In this article we show how these two forms of the credit assignment problem are equivalent. In this unified frame-work, a single-agent Markov decision process can be broken down into a single-time-step multi-agent process. Furthermore we show that Monte-Carlo estimation or Q-learning (depending on whether the values of resulting actions in the episode are known at the time of learning) are equivalent to different agent utility functions in a multi-agent system. This equivalence shows how an often neglected issue in multi-agent systems is equivalent to a well-known deficiency in multi-time-step learning and lays the basis for solving time-extended multi-agent problems, where both credit assignment problems are present.

  20. Research Problems in Developing Giftedness: A Worldwide Perspective.

    ERIC Educational Resources Information Center

    Passow, A. Harry; Schiff, Jacob H.

    1991-01-01

    This paper describes world perspectives on gifted education, focusing on definitions, identification procedures, and attitudes. It then examines key areas in gifted education that require further clarification and rigorous examination. (Author/JDD)

  1. Structural information in the inverse problem

    NASA Astrophysics Data System (ADS)

    Karaoulis, M.; Larson, T. H.; Ahmed, I.; Revil, A.; Thomason, J.

    2013-12-01

    Data integration in geophysics provides additional information to elucidate subsurface structure and reduce non-uniqueness of inverted models. There are several strategies for incorporating data integration into numerical models. A traditional approach is to use this information as a-priori knowledge, as an initial model or layer boundary specified on the mesh before the inversion. Although in some cases this approach has proven effective, the information is not directly incorporated into the inverse problem and might be lost in the final model. Another strategy is through joint inversion, where data and models are inverted simultaneous. The data integration comes from the joint operator as structural similarity or petrophysical equations. There are some limitations with this approach. In particular, structural similarity doesn't take into account different sensitivity patterns which differ for different geophysical methods, e.g. in a crosswell configuration electrical resistivity tomography is sensitive close to the borehole region while seismic waves are sensitive towards the center part. Moreover different methods have differing resolution. Therefore, a single joint operator might not be effective in all cases. In this work we demonstrate the use of image-guided inversion, where structural information is taken directly from a high resolution geophysical image (e.g. ground penetrating radar or seismic reflection) or from a geological cross-section. This structural information is introduced into the inverse problem through a weighted smoothing matrix, where it correlates and favors formations related to a specific structural feature and not just uniformly across the entire model. Both sharp and smooth features can be imaged and the recovered models can have a more realistic distribution of values. As an example of the method we use migrated seismic reflection images to extract the structural information and resistivity imaging to recover the resistivity

  2. Two-particle problem in comblike structures

    NASA Astrophysics Data System (ADS)

    Agliari, Elena; Cassi, Davide; Cattivelli, Luca; Sartori, Fabio

    2016-05-01

    Encounters between walkers performing a random motion on an appropriate structure can describe a wide variety of natural phenomena ranging from pharmacokinetics to foraging. On homogeneous structures the asymptotic encounter probability between two walkers is (qualitatively) independent of whether both walkers are moving or one is kept fixed. On infinite comblike structures this is no longer the case and here we deepen the mechanisms underlying the emergence of a finite probability that two random walkers will never meet, while one single random walker is certain to visit any site. In particular, we introduce an analytical approach to address this problem and even more general problems such as the case of two walkers with different diffusivity, particles walking on a finite comb and on arbitrary bundled structures, possibly in the presence of loops. Our investigations are both analytical and numerical and highlight that, in general, the outcome of a reaction involving two reactants on a comblike architecture can strongly differ according to whether both reactants are moving (no matter their relative diffusivities) or only one is moving and according to the density of shortcuts among the branches.

  3. The relativistic inverse stellar structure problem

    SciTech Connect

    Lindblom, Lee

    2014-01-14

    The observable macroscopic properties of relativistic stars (whose equations of state are known) can be predicted by solving the stellar structure equations that follow from Einstein’s equation. For neutron stars, however, our knowledge of the equation of state is poor, so the direct stellar structure problem can not be solved without modeling the highest density part of the equation of state in some way. This talk will describe recent work on developing a model independent approach to determining the high-density neutron-star equation of state by solving an inverse stellar structure problem. This method uses the fact that Einstein’s equation provides a deterministic relationship between the equation of state and the macroscopic observables of the stars which are composed of that material. This talk illustrates how this method will be able to determine the high-density part of the neutron-star equation of state with few percent accuracy when high quality measurements of the masses and radii of just two or three neutron stars become available. This talk will also show that this method can be used with measurements of other macroscopic observables, like the masses and tidal deformabilities, which can (in principle) be measured by gravitational wave observations of binary neutron-star mergers.

  4. Current structural vibration problems associated with noise

    NASA Technical Reports Server (NTRS)

    Mixson, J. S.

    1974-01-01

    As the performance of aerospace vehicles has increased, the noise generated by the propulsion system and by the passage of the vehicle through the air has also increased. Further increases in performance are now underway for space vehicles such as the space shuttle vehicle and for short distance takeoff and landing (STOL) aircraft, and are being planned for supersonic aircraft. The flight profiles and design features of these high-performance vehicles are reviewed and an estimate made of selected noise-induced structural vibration problems. Considerations for the prevention of acoustic fatigue, noise transmission, and electronic instrument malfunction are discussed.

  5. Glycoprotein Structural Genomics: Solving the Glycosylation Problem

    PubMed Central

    Chang, Veronica T.; Crispin, Max; Aricescu, A. Radu; Harvey, David J.; Nettleship, Joanne E.; Fennelly, Janet A.; Yu, Chao; Boles, Kent S.; Evans, Edward J.; Stuart, David I.; Dwek, Raymond A.; Jones, E. Yvonne; Owens, Raymond J.; Davis, Simon J.

    2007-01-01

    Summary Glycoproteins present special problems for structural genomic analysis because they often require glycosylation in order to fold correctly, whereas their chemical and conformational heterogeneity generally inhibits crystallization. We show that the “glycosylation problem” can be solved by expressing glycoproteins transiently in mammalian cells in the presence of the N-glycosylation processing inhibitors, kifunensine or swainsonine. This allows the correct folding of the glycoproteins, but leaves them sensitive to enzymes, such as endoglycosidase H, that reduce the N-glycans to single residues, enhancing crystallization. Since the scalability of transient mammalian expression is now comparable to that of bacterial systems, this approach should relieve one of the major bottlenecks in structural genomic analysis. PMID:17355862

  6. Reading Multimodal Texts: Perceptual, Structural and Ideological Perspectives

    ERIC Educational Resources Information Center

    Serafini, Frank

    2010-01-01

    This article presents a tripartite framework for analyzing multimodal texts. The three analytical perspectives presented include: (1) perceptual, (2) structural, and (3) ideological analytical processes. Using Anthony Browne's picturebook "Piggybook" as an example, assertions are made regarding what each analytical perspective brings to the…

  7. Computational strategies to address chromatin structure problems.

    PubMed

    Perišić, Ognjen; Schlick, Tamar

    2016-01-01

    While the genetic information is contained in double helical DNA, gene expression is a complex multilevel process that involves various functional units, from nucleosomes to fully formed chromatin fibers accompanied by a host of various chromatin binding enzymes. The chromatin fiber is a polymer composed of histone protein complexes upon which DNA wraps, like yarn upon many spools. The nature of chromatin structure has been an open question since the beginning of modern molecular biology. Many experiments have shown that the chromatin fiber is a highly dynamic entity with pronounced structural diversity that includes properties of idealized zig-zag and solenoid models, as well as other motifs. This diversity can produce a high packing ratio and thus inhibit access to a majority of the wound DNA. Despite much research, chromatin's dynamic structure has not yet been fully described. Long stretches of chromatin fibers exhibit puzzling dynamic behavior that requires interpretation in the light of gene expression patterns in various tissue and organisms. The properties of chromatin fiber can be investigated with experimental techniques, like in vitro biochemistry, in vivo imagining, and high-throughput chromosome capture technology. Those techniques provide useful insights into the fiber's structure and dynamics, but they are limited in resolution and scope, especially regarding compact fibers and chromosomes in the cellular milieu. Complementary but specialized modeling techniques are needed to handle large floppy polymers such as the chromatin fiber. In this review, we discuss current approaches in the chromatin structure field with an emphasis on modeling, such as molecular dynamics and coarse-grained computational approaches. Combinations of these computational techniques complement experiments and address many relevant biological problems, as we will illustrate with special focus on epigenetic modulation of chromatin structure. PMID:27345617

  8. Computational strategies to address chromatin structure problems

    NASA Astrophysics Data System (ADS)

    Perišić, Ognjen; Schlick, Tamar

    2016-06-01

    While the genetic information is contained in double helical DNA, gene expression is a complex multilevel process that involves various functional units, from nucleosomes to fully formed chromatin fibers accompanied by a host of various chromatin binding enzymes. The chromatin fiber is a polymer composed of histone protein complexes upon which DNA wraps, like yarn upon many spools. The nature of chromatin structure has been an open question since the beginning of modern molecular biology. Many experiments have shown that the chromatin fiber is a highly dynamic entity with pronounced structural diversity that includes properties of idealized zig-zag and solenoid models, as well as other motifs. This diversity can produce a high packing ratio and thus inhibit access to a majority of the wound DNA. Despite much research, chromatin’s dynamic structure has not yet been fully described. Long stretches of chromatin fibers exhibit puzzling dynamic behavior that requires interpretation in the light of gene expression patterns in various tissue and organisms. The properties of chromatin fiber can be investigated with experimental techniques, like in vitro biochemistry, in vivo imagining, and high-throughput chromosome capture technology. Those techniques provide useful insights into the fiber’s structure and dynamics, but they are limited in resolution and scope, especially regarding compact fibers and chromosomes in the cellular milieu. Complementary but specialized modeling techniques are needed to handle large floppy polymers such as the chromatin fiber. In this review, we discuss current approaches in the chromatin structure field with an emphasis on modeling, such as molecular dynamics and coarse-grained computational approaches. Combinations of these computational techniques complement experiments and address many relevant biological problems, as we will illustrate with special focus on epigenetic modulation of chromatin structure.

  9. Firefighter Hand Anthropometry and Structural Glove Sizing: A New Perspective

    PubMed Central

    Hsiao, Hongwei; Whitestone, Jennifer; Kau, Tsui-Ying; Hildreth, Brooke

    2015-01-01

    Objective We evaluated the current use and fit of structural firefighting gloves and developed an improved sizing scheme that better accommodates the U.S. firefighter population. Background Among surveys, 24% to 30% of men and 31% to 62% of women reported experiencing problems with the fit or bulkiness of their structural firefighting gloves. Method An age-, race/ethnicity-, and gender-stratified sample of 863 male and 88 female firefighters across the United States participated in the study. Fourteen hand dimensions relevant to glove design were measured. A cluster analysis of the hand dimensions was performed to explore options for an improved sizing scheme. Results The current national standard structural firefighting glove-sizing scheme underrepresents firefighter hand size range and shape variation. In addition, mismatch between existing sizing specifications and hand characteristics, such as hand dimensions, user selection of glove size, and the existing glove sizing specifications, is significant. An improved glove-sizing plan based on clusters of overall hand size and hand/finger breadth-to-length contrast has been developed. Conclusion This study presents the most up-to-date firefighter hand anthropometry and a new perspective on glove accommodation. The new seven-size system contains narrower variations (standard deviations) for almost all dimensions for each glove size than the current sizing practices. Application The proposed science-based sizing plan for structural firefighting gloves provides a step-forward perspective (i.e., including two women hand model–based sizes and two wide-palm sizes for men) for glove manufacturers to advance firefighter hand protection. PMID:26169309

  10. Problem Solving in the School Curriculum from a Design Perspective

    ERIC Educational Resources Information Center

    Toh, Tin Lam; Leong, Yew Hoong; Dindyal, Jaguthsing; Quek, Khiok Seng

    2010-01-01

    In this symposium, the participants discuss some preliminary data collected from their problem solving project which uses a design experiment approach. Their approach to problem solving in the school curriculum is in tandem with what Schoenfeld (2007) claimed: "Crafting instruction that would make a wide range of problem-solving strategies…

  11. Team-Based Complex Problem Solving: A Collective Cognition Perspective

    ERIC Educational Resources Information Center

    Hung, Woei

    2013-01-01

    Today, much problem solving is performed by teams, rather than individuals. The complexity of these problems has exceeded the cognitive capacity of any individual and requires a team of members to solve them. The success of solving these complex problems not only relies on individual team members who possess different but complementary expertise,…

  12. Sound absorption by subwavelength membrane structures: A geometric perspective

    NASA Astrophysics Data System (ADS)

    Yang, Min; Li, Yong; Meng, Chong; Fu, Caixing; Mei, Jun; Yang, Zhiyu; Sheng, Ping

    2015-12-01

    Decorated membranes comprising a thin layer of elastic film with small rigid platelets fixed on top have been found to be efficient absorbers of low-frequency sound. In this work we consider the problem of sound absorption from a perspective aimed at deriving upper bounds under different scenarios, i.e., whether the sound is incident from one side only or from both sides, and whether there is a reflecting surface on the back side of the membrane. By considering the negligible thickness of the membrane, usually on the order of a fraction of one millimeter, we derive a relation showing that the sum of the incoming sound waves' (complex) pressure amplitudes, averaged over the area of the membrane, must be equal to that of the outgoing waves. By using this relation, and without going to any details of the wave solutions, it is shown that the maximum absorption achievable from one-sided incidence is 50%, while the maximum absorption with a back-reflecting surface can reach 100%. The latter was attained by the hybridized resonances. All the results are shown to be in excellent agreement with the experiments. This generalized perspective, when used together with the Green function's formalism, can be useful in gaining insights into the constraints on what are achievable in scatterings and absorption by thin film structures and delineating them.

  13. Triumph or Triage? The World Food Problem in Geographical Perspective. Resource Paper No. 75-3.

    ERIC Educational Resources Information Center

    Knight, C. Gregory; Wilcox, R. Paul

    Emphasizing a problem-solving perspective, the document investigates the world food scene. Simply defined, the world food problem is the apparent inability of the world's people to feed themselves adequately and consistently. Intended for use by college level geography instructors as they develop courses on human uses of the environment, the…

  14. Solving Spatial Perspective-Taking Problems by Rule vs. Computation: A Developmental Study.

    ERIC Educational Resources Information Center

    Flavell, John H.; And Others

    This paper describes two experiments in which children in grades 1, 3, and 5 were given three kinds of spatial perspective-taking problems to solve as quickly as they could: (1) C problems, solvable only by computation (that is, noting which features of a particular object array were closest to another observer in order to estimate how the array…

  15. Externalizing Behavior Problems during Adolescence: An Ecological Perspective

    ERIC Educational Resources Information Center

    White, Rachel; Renk, Kimberly

    2012-01-01

    Given the ramifications of difficulties related to externalizing behavior problems, the present study examined the relationships among adolescents' externalizing behavior problems, characteristics of adolescents' families, their perceived neighborhood support, and their acculturation. As part of this study, a culturally diverse sample of…

  16. Problem-Based Learning: A Critical Rationalist Perspective

    ERIC Educational Resources Information Center

    Parton, Graham; Bailey, Richard

    2008-01-01

    Although problem-based learning is being adopted by many institutions around the world as an effective model of learning in higher education, there is a surprising lack of critique in the problem-based learning literature in relation to its philosophical characteristics. This paper explores epistemology as a starting point for investigating the…

  17. Youth Education and Unemployment Problems. An International Perspective.

    ERIC Educational Resources Information Center

    Gordon, Margaret S.; Trow, Martin

    Essays focusing on issues concerning youth education and unemployment problems are presented in this document. It is divided into three general areas. The first, Youth Unemployment in Western Industrial Countries, reviews general dimensions of the problem, the cyclical hypothesis, the demand hypothesis, the supply hypothesis, disaggregating…

  18. Dyscalculia and Other Learning Problems in Arithmetic: A Historical Perspective.

    ERIC Educational Resources Information Center

    Sharma, Mahesh C.

    1986-01-01

    Evidence on learning problems due to dyscalculia is surveyed. Definitions, factors responsible for dyscalculia, split-brain research and hemispheric roles, mathematics learning problems and personality, materials for instruction, and levels of knowing mathematics are among the topics discussed with an extensive list of references. (MNS)

  19. Facilitating Flexible Problem Solving: A Cognitive Load Perspective

    ERIC Educational Resources Information Center

    Kalyuga, Slava; Renkl, Alexander; Paas, Fred

    2010-01-01

    The development of flexible, transferable problem-solving skills is an important aim of contemporary educational systems. Since processing limitations of our mind represent a major factor influencing any meaningful learning, the acquisition of flexible problem-solving skills needs to be based on known characteristics of our cognitive architecture…

  20. Problem Solving in Technology Education: A Taoist Perspective.

    ERIC Educational Resources Information Center

    Flowers, Jim

    1998-01-01

    Offers a new approach to teaching problem solving in technology education that encourages students to apply problem-solving skills to improving the human condition. Suggests that technology teachers incorporate elements of a Taoist approach in teaching by viewing technology as a tool with a goal of living a harmonious life. (JOW)

  1. Problems and Opportunities in School Financial Management: A Consultant's Perspective.

    ERIC Educational Resources Information Center

    Chabotar, Kent John

    1987-01-01

    Summarizes major problems in school financial management and suggests practical improvements to aid external reporting of financial data and internal management. Sections of the article describe these categories of problems: (1) budget presentation; (2) management control; (3) cost accounting; and (4) financial reporting. (PS)

  2. Effects of Exposure to Microwaves: Problems and Perspectives*

    PubMed Central

    Michaelson, Sol M.

    1974-01-01

    During the last 25 years, there has been a remarkable development and increase in the number of processes and devices that utilize or emit microwaves. Such devices are used in all sectors of our society for military, industrial, telecommunications, and consumer applications. Although there is information on biologic effects and potential hazard to man from exposure to microwaves, considerable confusion and misinformation has permeated not only the public press but also some scientific and technical publications. The purpose of this review is to place the available information on biologic effects of microwaves in proper perspective and to suggest approaches to future studies. PMID:4620329

  3. Bringing a Bayesian Perspective to Large Dimensional Problems in Geophysics

    NASA Astrophysics Data System (ADS)

    Duputel, Z.; Simons, M.; Jolivet, R.; Zaroli, C.; Rivera, L. A.; Ampuero, J. P.; Gombert, B.; Minson, S. E.

    2015-12-01

    The last decade has seen a substantial expansion of geophysical observations. Exploiting this wealth of data involves large ill-conditioned inverse problems requiring large numbers of uncertain parameters. A common approach in geophysics is to use some form of regularization that transforms the inversion into a well-conditioned optimization problem. While this approach is convenient and computationally inexpensive, the inherent non-uniqueness of our problems suggest that we should not simply search for a single optimal model, but rather attempt to describe the ensemble of plausible models that can fit the data and are consistent with prior information. This talk will present various applications of full Bayesian analysis techniques to large ill-posed inverse problems in geophysics. Despite significant computational cost, Bayesian sampling is a powerful tool to combine prior information, theoretical knowledge and data in order to address scientific problems probabilistically. We shall illustrate this by showing recent results for two types of problems: (1) the study of earthquakes sources and (2) imaging of the Earth interior. In particular, we will present different strategies that can be employed in order to achieve realistic uncertainty estimates.

  4. [Preimplantation Genetic Diagnosis by Blastocentesis: Problems and Perspectives].

    PubMed

    Zhigalina, D I; Skryabin, N A; Artyukhova, V G; Svetlakov, A V; Lebedev, I N

    2016-01-01

    The discovery of cell-free DNA in blastocoele fluid opens new perspectives for the development of preimplantation genetic diagnosis of human chromosomal and genetic diseases. In this review we analyzed the results of the first studies, which made it possible to evaluate the effectiveness of the application of a new source of biological material and showed a high degree of agreement between the results of molecular karyotyping with cell-free DNA and blastocyst cells. The results suggest the possibility of developing a noninvasive method of preimplantation genetic diagnosis, which may open a new round of progress in the field of assisted reproductive technologies and the genetics of early stages of human ontogenesis. PMID:27183788

  5. Characteristics of Problems for Problem-Based Learning: The Students' Perspective

    ERIC Educational Resources Information Center

    Sockalingam, Nachamma; Schmidt, Henk G.

    2011-01-01

    This study aimed to identify salient problem characteristics perceived by students in problem-based curricula. To this end, reflective essays from biomedical students (N = 34) on characteristics of good problems were text-analyzed. Students identified eleven characteristics, of which they found the extent to which the problem leads to desired…

  6. Melt Structure and Properties: a Spectroscopic Perspective

    NASA Astrophysics Data System (ADS)

    Stebbins, J.

    2006-12-01

    Entropy, volume, and their P/T derivatives are at the heart of models of the thermodynamics of silicate melts and magmas. Quantitative characterization of glass structure is leading to important new insights into the links from "Microscopic to Macroscopic" that can at least guide interpretations of data and in some cases even have predictive power. A few recent examples will be discussed here. The often-large configurational components to heat capacities, thermal expansivities, and compressibilities of melts strongly indicate that structural changes with temperature and pressure are of key importance. At least some aspects of thermal increases in configurational (as opposed to vibrational) disorder are amenable to spectroscopic detection, either with in situ methods or on glasses with varying quench rates and thus varying fictive temperatures. In some systems, such changes are now clear, and can be shown to make significant contributions to properties. These include network cation coordination in systems such as borate liquids (BO4 to BO3 at higher T), and Al-Si disordering in aluminosilicates. In general, however, progress in this rich problem has only begun. It has long been suspected from thermodynamic analyses (and theoretical simulations) that configurational changes in melts play a key role in volume compression at high pressure, over and above that which can be expressed in "normal" equations of state or from those expected from bond compression and bending. Scattering and spectroscopic studies have revealed some of the important aspects of pressure-induced structural changes, but again we are just at the beginning of full understanding. For example, binary silicate glasses quenched from high-P melts clearly record some systematic increases in Si coordination, while aluminosilicates record systematic pressure and compositional (modifier cation field strength) effects on Al coordination in recovered samples with large, quenched-in density increases

  7. The experiences of nurses with mental health problems: colleagues' perspectives.

    PubMed

    Joyce, Terry; Higgins, Isabel; Magin, Parker; Goode, Susan; Pond, Dimity; Stone, Teresa; Elsom, Stephen; O'Neill, Kerry

    2012-08-01

    A 3-stage qualitative study conducted in 2008 aimed to explore the issues to inform a mental health education program to deliver to nurses. This article presents the findings of Stage 1. Data were collected from semistructured interviews conducted with 14 Australian nurses. The interviews explored nurses' knowledge and understanding of mental health problems and their workplace experiences of working with nurses with mental health problems. The interviews were audiotaped, transcribed, and analyzed for the main themes: textbook knowledge, day-to-day support, and workplace considerations. These nurses' narratives guided the implementation of a mental health education workshop targeting nurses (Stage 2). PMID:22835752

  8. Problems and Potentials of Construction Cost Analysis: The State Perspective

    ERIC Educational Resources Information Center

    Keegan, Mary E.; Cohen, Edward

    1978-01-01

    Developing comparable data for policy-making and financial support allocation for health professions education creates difficult problems for state-level decision-makers. The experience of the New Jersey Department of Higher Education in collaboration with the College of Medicine and Dentistry of New Jersey is reported. (Author/LBH)

  9. Accumulation of Welfare Problems in a Longitudinal Perspective

    ERIC Educational Resources Information Center

    Hallerod, Bjorn; Bask, Miia

    2008-01-01

    The central aim of the present paper is to analyse the degree to which welfare problems accumulate over time and to what extent such an accumulation is related to class position and household formation. We utilize longitudinal data from the Swedish Survey of Living Conditions, following a panel that was first interviewed in 1979 and, thereafter,…

  10. A Neuropsychological Perspective on Attention Problems in Neurofibromatosis Type 1

    ERIC Educational Resources Information Center

    Templer, Alexandra K.; Titus, Jeffrey B.; Gutmann, David H.

    2013-01-01

    Cognitive problems are common in children with neurofibromatosis type 1 and they can often complicate treatment. The current literature review examines cognitive functioning in neurofibromatosis type 1, with a specific focus on executive functioning. This includes exploration of how deficits in executive functioning are expressed in children with…

  11. A Historical Perspective on Problems in Botany Teaching.

    ERIC Educational Resources Information Center

    Hershey, David R.

    1996-01-01

    Discusses how the many problems in botany teaching are interrelated and most have existed since at least the early 1900s. Considers botany teaching at both the precollege and introductory college levels. Discusses botany neglect in biology teaching, botanical illiteracy, uninteresting or irrelevant botany teaching, zoochauvinism, research…

  12. Adolescent Health Problems: Behavioral Perspectives. Advances in Pediatric Psychology.

    ERIC Educational Resources Information Center

    Wallander, Jan L., Ed.; Siegel, Lawrence J., Ed.

    This book examines the relationship between adolescent risk-taking behaviors and health. The health-related problems of adolescents frequently are manifestations of social, economic, or behavioral factors. Following an overview (Siegal), the chapters in the first section of the book explore general and conceptual issues: (1) "Epidemiology of…

  13. Glasnost and the Business Information Sector: Soviet Problems and Perspectives.

    ERIC Educational Resources Information Center

    Konn, Tania

    1991-01-01

    Discussion of the effect of glasnost on the availability of business information from the Soviet Union and Eastern Europe highlights online services.These include general information sources, specialized business services, industry-specific services, new services, and forthcoming developments. Problems in dealing with the increased availability of…

  14. Perspective on Microfluidic Cell Separation: A Solved Problem?

    PubMed Central

    2015-01-01

    The purification and sorting of cells using microfluidic methodologies has been a remarkably active area of research over the past decade. Much of the scientific and technological work associated with microfluidic cell separation has been driven by needs in clinical diagnostics and therapeutic monitoring, most notably in the context of circulating tumor cells. The last several years have seen advances in a broad range of separation modalities ranging from miniaturized analogs of established techniques such as fluorescence- and magnetic-activated cell sorting (FACS and MACS, respectively), to more specialized approaches based on affinity, dielectrophoretic mobility, and inertial properties of cells. With several of these technologies nearing commercialization, there is a sense that the field of microfluidic cell separation has achieved a high level of maturity over an unusually short span of time. In this Perspective, we set the stage by describing major scientific and technological advances in this field and ask what the future holds. While many scientific questions remain unanswered and new compelling questions will undoubtedly arise, the relative maturity of this field poses some unique challenges. PMID:25350696

  15. Four years of problem-based learning: a student's perspective.

    PubMed Central

    von Doebeln, G.

    1996-01-01

    After four years as a student in a medical school using problem-based learning I still find it an excellent way to learn. Group work has developed my personal skills and abilities. Learning how to obtain knowledge on my own has given me independence and confidence. Motivation to study has been encouraged by early clinical experience. Training in critical thinking has been further enhanced by in-depth studies. Medical education at the University of Linkoping has developed over the years and a contributing factor has been students' involvement in designing the medical training. There are benefits and disadvantages with problem-based learning, but on the whole it is an enjoyable and fruitful experience. Images p98-a PMID:8871459

  16. Modelling Ill-Structured Problem Solving with Schema Theory.

    ERIC Educational Resources Information Center

    Nagy, Philip

    This study assesses the ability of schema theory to address ill-structured problems without becoming unwieldy. Prior to addressing the study proper, the paper reviews the literature on memory for complex phenomena, ill-structured problems, expert-novice differences, administration as problem solving, and assessment of complex learning outcomes.…

  17. Bipolar disorder-methodological problems and future perspectives

    PubMed Central

    Angst, Jules

    2008-01-01

    Since its “rebirth” in 1966, bipolar disorder (BPD) has rapidly come to occupy a central position in the research and treatment of mood disorders. Compared with major depressive disorder (MDD), BPD is a more serious condition, characterized by much more frequent recurrence, more complex comorbidity, and higher mortality. One major problem is the lack of valid definitions in adult and in child psychiatry; the current definitions are unsatisfactory, and heavily favor an overdiagnosis of MDD. Biological research is partially based on those definitions, which have a short half-life. An additional, dimensional, approach, quantifying hypomania, depression, and anxiety by self-assessment and symptom checklists is recommended, A further, related problem is the early recognition of the onset of BPD, especially in adolescence, and the identification of correlates in childhood. Early and timely diagnosis of BPD is necessary to enable prompt intervention and secondary prevention of the disorder. The paper describes the current status and future directions of developing clinical concepts of bipolarity PMID:18689284

  18. The Problems of "Competence" and Alternatives from the Scandinavian Perspective of "Bildung"

    ERIC Educational Resources Information Center

    Willbergh, Ilmi

    2015-01-01

    The paper aims to show how competence as an educational concept for the 21st century is struggling with theoretical problems for which the concept of "Bildung" in the European tradition can offer alternatives, and to discuss the possibility of developing a sustainable educational concept from the perspectives of competence and…

  19. International Perspectives on Problem-Based Learning: Contexts, Cultures, Challenges, and Adaptations

    ERIC Educational Resources Information Center

    Hmelo-Silver, Cindy E.

    2012-01-01

    The theme of this special issue is timely as the world becomes increasingly flat and globally connected (Friedman, 2007). By focusing on an international perspective in problem-based learning (PBL), it puts culture squarely in the center, whether it is a national or disciplinary culture. The articles in this special issue represent Thailand, South…

  20. Learner Perspectives of Online Problem-Based Learning and Applications from Cognitive Load Theory

    ERIC Educational Resources Information Center

    Chen, Ruth

    2016-01-01

    Problem-based learning (PBL) courses have historically been situated in physical classrooms involving in-person interactions. As online learning is embraced in higher education, programs that use PBL can integrate online platforms to support curriculum delivery and facilitate student engagement. This report describes student perspectives of the…

  1. Problem-Based Learning in a Physical Therapy Program and Subsequent Clinical Practice: The Practitioners' Perspectives.

    ERIC Educational Resources Information Center

    Wilson, Stanley H.; Gallagher, Jo D.; Elbaum, Leonard; Smith, Douglas H.

    This study examined the perspectives of three graduates of a problem-based learning (PBL) physical therapy (PT) program about their clinical practice. Researchers used qualitative methods of observation, interview, and journaling to gather the data. Three sessions of audiotaped interviews and two observation sessions were conducted with the three…

  2. Using Ontological Engineering to Overcome AI-ED Problems: Contribution, Impact and Perspectives

    ERIC Educational Resources Information Center

    Mizoguchi, Riichiro; Bourdeau, Jacqueline

    2016-01-01

    This article reflects on the ontology engineering methodology discussed by the paper entitled "Using Ontological Engineering to Overcome AI-ED Problems" published in this journal in 2000. We discuss the achievements obtained in the last 10 years, the impact of our work as well as recent trends and perspectives in ontology engineering for…

  3. The cosmological 7Li problem from a nuclear physics perspective

    NASA Astrophysics Data System (ADS)

    Broggini, C.; Canton, L.; Fiorentini, G.; Villante, F. L.

    2012-06-01

    The primordial abundance of 7Li as predicted by Big Bang Nucleosynthesis (BBN) is more than a factor 2 larger than what has been observed in metal-poor halo stars. Herein, we analyze the possibility that this discrepancy originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. To do this, we introduce an efficient method to calculate the changes in the 7Li abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. Then, considering that 7Li is mainly produced from 7Be via the electron capture process 7Be+e- → 7Li+νe, we assess the impact of the various channels of 7Be destruction. Differently from previous analysis, we consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration and that does not rely on the use of the narrow-resonance approximation. As a result of this, the possibility of a nuclear physics solution to the 7Li problem is significantly suppressed. Given the present experimental and theoretical constraints, it is unlikely that the 7Be+n destruction rate is underestimated by the 2.5 factor required to solve the problem. We exclude, moreover, that resonant destruction in the channels 7Be+t and 7Be+3He can explain the 7Li puzzle. New unknown resonances in 7Be+d and 7Be+α could potentially produce significant effects. Recent experimental results have ruled out such a possibility for 7Be+d. On the other hand, for the 7Be+α channel very favorable conditions are required. The possible existence of a partially suitable resonant level in 11C is studied in the framework of a coupled-channel model and the possibility of a direct measurement is considered.

  4. PREFACE: Open Problems in Nuclear Structure Theory: Introduction Open Problems in Nuclear Structure Theory: Introduction

    NASA Astrophysics Data System (ADS)

    Dobaczewski, Jacek

    2010-06-01

    Nuclear structure theory is a domain of physics faced at present with great challenges and opportunities. A larger and larger body of high-precision experimental data has been and continues to be accumulated. Experiments on very exotic short-lived isotopes are the backbone of activity at numerous large-scale facilities. Over the years, tremendous progress has been made in understanding the basic features of nuclei. However, the theoretical description of nuclear systems is still far from being complete and is often not very precise. Many questions, both basic and practical, remain unanswered. The goal of publishing this special focus issue of Journal of Physics G: Nuclear and Particle Physics on Open Problems in Nuclear Structure Theory (OPeNST) is to construct a fundamental inventory thereof, so that the tasks and available options become more clearly exposed and that this will help to stimulate a boost in theoretical activity, commensurate with the experimental progress. The requested format and scope of the articles on OPeNST was quite flexible. The journal simply offered the possibility to provide a forum for the material, which is very often discussed at conferences during the coffee breaks but does not normally have sufficient substance to form regular publications. Nonetheless, very often formulating a problem provides a major step towards its solution, and it may constitute a scientific achievement on its own. Prospective authors were therefore invited to find their own balance between the two extremes of very general problems on the one hand (for example, to solve exactly the many-body equations for a hundred particles) and very specific problems on the other hand (for example, those that one could put in one's own grant proposal). The authors were also asked not to cover results already obtained, nor to limit their presentations to giving a review of the subject, although some elements of those could be included to properly introduce the subject matter

  5. [Health system in Afghanistan: problems and institutional perspectives].

    PubMed

    Lejars, M

    2008-10-01

    Afghanistan has been ravaged by years of conflict. To provide emergency services and restore access health services, the Public Health Ministry with the assistance of partners developed first a package of basic health services delivered by NGO contractors and second a package of essential hospital services. The Ministry's role consists of providing guidance. To reduce the many issues and problems affecting this role, reforms are now being undertaken and a new national health care strategy is being developed within the framework of the National Development Strategy. An institution-building project has been initiated with European Union funding to allow the Health Ministry to carry out its stewardship and management functions with greater effectiveness and transparency. This project is essential for the successful outcome of all future strategies and programs planned by the Health Ministry to enhance its institutional effectiveness. The objectives of this project are to strengthen planning and auditing activities, promote quality assurance, implement funding mechanisms for health-related activities, organize management of human resources, maintain ongoing efforts to reform the administration and fight against corruption, and lay the foundations for managing finances and procurement. The scope of this project underlines the importance of its outcome. However the institution-building process will be long and constantly threatened by political instability and insecurity. PMID:19068975

  6. Determination of channeling perspectives for complex crystal structures

    SciTech Connect

    Allen, W.R.

    1993-03-01

    Specification of the atomic arrangement for axes and planes of high symmetry is essential for crystal alignment using Rutherford backscattering and for studies of the lattice location of impurities in single crystals. By rotation of an inscribed orthogonal coordinate system, a visual image for a given perspective of a crystal structure can be specified. Knowledge of the atomic arrangement permits qualitative channeling perspectives to be visualized and calculation of continuum potentials for channeling. Channeling angular-yield profiles can then be analytically modeled and, subsequently, shadowing by host atoms of positions within the unit cell predicted. Software to calculate transformed atom positions for a channeling perspective in a single crystal are described and illustrated for the spinel crystal structure.

  7. Current perspectives on RNA secondary structure probing.

    PubMed

    Kenyon, Julia; Prestwood, Liam; Lever, Andrew

    2014-08-01

    The range of roles played by structured RNAs in biological systems is vast. At the same time as we are learning more about the importance of RNA structure, recent advances in reagents, methods and technology mean that RNA secondary structural probing has become faster and more accurate. As a result, the capabilities of laboratories that already perform this type of structural analysis have increased greatly, and it has also become more widely accessible. The present review summarizes established and recently developed techniques. The information we can derive from secondary structural analysis is assessed, together with the areas in which we are likely to see exciting developments in the near future. PMID:25110033

  8. On some structure-turbulence interaction problems

    NASA Technical Reports Server (NTRS)

    Maekawa, S.; Lin, Y. K.

    1976-01-01

    The interactions between a turbulent flow structure; responding to its excitation were studied. The turbulence was typical of those associated with a boundary layer, having a cross-spectral density indicative of convection and statistical decay. A number of structural models were considered. Among the one-dimensional models were an unsupported infinite beam and a periodically supported infinite beam. The fuselage construction of an aircraft was then considered. For the two-dimensional case a simple membrane was used to illustrate the type of formulation applicable to most two-dimensional structures. Both the one-dimensional and two-dimensional structures studied were backed by a cavity filled with an initially quiescent fluid to simulate the acoustic environment when the structure forms one side of a cabin of a sea vessel or aircraft.

  9. Problem-Based Learning: Using Ill-Structured Problems in Biology Project Work

    ERIC Educational Resources Information Center

    Chin, Christine; Chia, Li-Gek

    2006-01-01

    This case study involved year 9 students carrying out project work in biology via problem-based learning. The purpose of the study was to (a) find out how students approach and work through ill-structured problems, (b) identify some issues and challenges related to the use of such problems, and (c) offer some practical suggestions on the…

  10. Perspective view. Fivestory reinforced concrete factory building reveals the structural ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view. Five-story reinforced concrete factory building reveals the structural frame on the exterior of the facade. Twelve bay facade facing onto Clay Avenue (north facade) has first floor openings bricked up. Mix of typical factory windows and glass block windows fill the majority of the openings on the rest of building - Russell Industrial Center, 1600 Clay Avenue, Detroit, MI

  11. A structural perspective of compensatory evolution

    PubMed Central

    Ivankov, Dmitry N; Finkelstein, Alexei V; Kondrashov, Fyodor A

    2014-01-01

    The study of molecular evolution is important because it reveals how protein functions emerge and evolve. Recently, several types of studies indicated that substitutions in molecular evolution occur in a compensatory manner, whereby the occurrence of a substitution depends on the amino acid residues at other sites. However, a molecular or structural basis behind the compensation often remains obscure. Here, we review studies on the interface of structural biology and molecular evolution that revealed novel aspects of compensatory evolution. In many cases structural studies benefit from evolutionary data while structural data often add a functional dimension to the study of molecular evolution. PMID:24981969

  12. RNA structure in splicing: An evolutionary perspective.

    PubMed

    Lin, Chien-Ling; Taggart, Allison J; Fairbrother, William G

    2016-09-01

    Pre-mRNA splicing is a key post-transcriptional regulation process in which introns are excised and exons are ligated together. A novel class of structured intron was recently discovered in fish. Simple expansions of complementary AC and GT dimers at opposite boundaries of an intron were found to form a bridging structure, thereby enforcing correct splice site pairing across the intron. In some fish introns, the RNA structures are strong enough to bypass the need of regulatory protein factors for splicing. Here, we discuss the prevalence and potential functions of highly structured introns. In humans, structured introns usually arise through the co-occurrence of C and G-rich repeats at intron boundaries. We explore the potentially instructive example of the HLA receptor genes. In HLA pre-mRNA, structured introns flank the exons that encode the highly polymorphic β sheet cleft, making the processing of the transcript robust to variants that disrupt splicing factor binding. While selective forces that have shaped HLA receptor are fairly atypical, numerous other highly polymorphic genes that encode receptors contain structured introns. Finally, we discuss how the elevated mutation rate associated with the simple repeats that often compose structured intron can make structured introns themselves rapidly evolving elements. PMID:27454491

  13. Interlocked Problem Posing and Children's Problem Posing Performance in Free Structured Situations

    ERIC Educational Resources Information Center

    Cankoy, Osman

    2014-01-01

    The aim of this study is to explore the mathematical problem posing performance of students in free structured situations. Two classes of fifth grade students (N = 30) were randomly assigned to experimental and control groups. The categories of the problems posed in free structured situations by the 2 groups of students were studied through…

  14. Minimum structural controllability problems of complex networks

    NASA Astrophysics Data System (ADS)

    Yin, Hongli; Zhang, Siying

    2016-02-01

    Controllability of complex networks has been one of the attractive research areas for both network and control community, and has yielded many promising and significant results in minimum inputs and minimum driver vertices. However, few studies have been devoted to studying the minimum controlled vertex set through which control over the network with arbitrary structure can be achieved. In this paper, we prove that the minimum driver vertices driven by different inputs are not sufficient to ensure the full control of the network when the associated graph contains the inaccessible strongly connected component which has perfect matching and propose an algorithm to identify a minimum controlled vertex set for network with arbitrary structure using convenient graph and mathematical tools. And the simulation results show that the controllability of network is correlated to the number of inaccessible strongly connected components which have perfect matching and these results promote us to better understand the relationship between the network's structural characteristics and its control.

  15. Local structure of equality constrained NLP problems

    SciTech Connect

    Mari, J.

    1994-12-31

    We show that locally around a feasible point, the behavior of an equality constrained nonlinear program is described by the gradient and the Hessian of the Lagrangian on the tangent subspace. In particular this holds true for reduced gradient approaches. Applying the same ideas to the control of nonlinear ODE:s, one can device first and second order methods that can be applied also to stiff problems. We finally describe an application of these ideas to the optimization of the production of human growth factor by fed-batch fermentation.

  16. SPS structures and control: A perspective

    NASA Technical Reports Server (NTRS)

    Ried, R. C.

    1980-01-01

    The characteristics and design requirements for the structure and control systems for a solar power satellite were evaluated. A simplistic, indicative analysis on a representative configuration was developed. Representative configuration masses and dimensions are given in convenient approximate magnitudes. The significance of structure control interaction and the significance of stiffness to the minimization of dynamic energy was demonstrated. It was found that the thermal environment for the SPS was dominated by solar radiation and waste heat rejection by the antenna. A more in-depth assessment of the control system design and associated system performance is still needed, specifically the inter-relatonships between control sensors, actuators, and structural response.

  17. Interface Problems: Structural Constraints on Interpretation?

    ERIC Educational Resources Information Center

    Frazier, Lyn; Clifton, Charles; Rayner, Keith; Deevy, Patricia; Koh, Sungryong; Bader, Markus

    2005-01-01

    Five experiments investigated the interpretation of quantified noun phrases in relation to discourse structure. They demonstrated, using questionnaire and on-line reading techniques, that readers in English prefer to give a quantified noun phrase in (VP-external) subject position a presuppositional interpretation, in which the noun phrase limits…

  18. New Perspectives on Structured Life Education Groups.

    ERIC Educational Resources Information Center

    Apgar, Kathryn; Coplon, Jennifer Kane

    1985-01-01

    Defines life education groups as educational, time-limited groups focusing on family and personal growth issues. Discusses the conceptual framework of the groups, the value of structure, prevention and intervention, and responding to the needs of diverse groups. (JAC)

  19. A Topological Perspective of Neural Network Structure

    NASA Astrophysics Data System (ADS)

    Sizemore, Ann; Giusti, Chad; Cieslak, Matthew; Grafton, Scott; Bassett, Danielle

    The wiring patterns of white matter tracts between brain regions inform functional capabilities of the neural network. Indeed, densely connected and cyclically arranged cognitive systems may communicate and thus perform distinctly. However, previously employed graph theoretical statistics are local in nature and thus insensitive to such global structure. Here we present an investigation of the structural neural network in eight healthy individuals using persistent homology. An extension of homology to weighted networks, persistent homology records both circuits and cliques (all-to-all connected subgraphs) through a repetitive thresholding process, thus perceiving structural motifs. We report structural features found across patients and discuss brain regions responsible for these patterns, finally considering the implications of such motifs in relation to cognitive function.

  20. Structural dynamics technology research in NASA: Perspective on future needs

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The perspective of a NASA ad hoc study group on future research needs in structural dynamics within the aerospace industry is presented. The common aspects of the design process across the industry are identified and the role of structural dynamics is established through a discussion of various design considerations having their basis in structural dynamics. The specific structural dynamics issues involved are identified and assessed as to their current technological status and trends. Projections of future requirements based on this assessment are made and areas of research to meet them are identified.

  1. Solving Fluid Structure Interaction Problems with an Immersed Boundary Method

    NASA Technical Reports Server (NTRS)

    Barad, Michael F.; Brehm, Christoph; Kiris, Cetin C.

    2016-01-01

    An immersed boundary method for the compressible Navier-Stokes equations can be used for moving boundary problems as well as fully coupled fluid-structure interaction is presented. The underlying Cartesian immersed boundary method of the Launch Ascent and Vehicle Aerodynamics (LAVA) framework, based on the locally stabilized immersed boundary method previously presented by the authors, is extended to account for unsteady boundary motion and coupled to linear and geometrically nonlinear structural finite element solvers. The approach is validated for moving boundary problems with prescribed body motion and fully coupled fluid structure interaction problems. Keywords: Immersed Boundary Method, Higher-Order Finite Difference Method, Fluid Structure Interaction.

  2. Androgen-metabolizing enzymes: A structural perspective.

    PubMed

    Manenda, Mahder Seifu; Hamel, Charles Jérémie; Masselot-Joubert, Loreleï; Picard, Marie-Ève; Shi, Rong

    2016-07-01

    Androgen-metabolizing enzymes convert cholesterol, a relatively inert molecule, into some of the most potent chemical messengers in vertebrates. This conversion involves thermodynamically challenging reactions catalyzed by P450 enzymes and redox reactions catalyzed by Aldo-Keto Reductases (AKRs). This review covers the structures of these enzymes with a focus on active site interactions and proposed mechanisms. Due to their role in a number of diseases, particularly in cancer, androgen-metabolizing enzymes have been targets of drug design. Hence we will also highlight how existing knowledge of structure is being used to this end. PMID:26924584

  3. New perspectives on the Popigai impact structure

    NASA Technical Reports Server (NTRS)

    Garvin, J. B.; Deino, A. L.

    1992-01-01

    The record of large-scale cratering on Earth is scant, and the only currently 'proven' 100-km-class impact structure known to have formed within the Cenozoic is Popigai, located in the Siberian Arctic at 71.5 deg N, 111 deg E. Popigai is clearly a multiringed impact basin formed within the crystalline shield rocks (Anabar) and platform sediments of the Siberian taiga, and estimates of the volume of preserved impact melt typically exceed 1700 cu km, which is within a factor of 2-3 of what would be predicted using scaling relationships. We present the preliminary results of an analysis of the present-day topography of the Popigai structure, together with refined absolute age estimates, in order to reconstruct the pre-erosional morphology of the basin, as well as to quantify the erosion or sediment infill rates in the Popigai region.

  4. HSCT materials and structures: An MDC perspective

    NASA Technical Reports Server (NTRS)

    Sutton, Jay O.

    1992-01-01

    The key High Speed Civil Transport (HSCT) features which control the materials selection are discussed. Materials are selected based on weight and production economics. The top-down and bottoms-up approaches to material selection are compared for the Mach 2.4 study baseline aircraft. The key materials and structures related tasks which remain to be accomplished prior to proceeding with the building of the HSCT aircraft are examined.

  5. Sphingosine-1-phosphate metabolism: A structural perspective.

    PubMed

    Pulkoski-Gross, Michael J; Donaldson, Jane C; Obeid, Lina M

    2015-01-01

    Sphingolipids represent an important class of bioactive signaling lipids which have key roles in numerous cellular processes. Over the last few decades, the levels of bioactive sphingolipids and/or their metabolizing enzymes have been realized to be important factors involved in disease development and progression, most notably in cancer. Targeting sphingolipid-metabolizing enzymes in disease states has been the focus of many studies and has resulted in a number of pharmacological inhibitors, with some making it into the clinic as therapeutics. In order to better understand the regulation of sphingolipid-metabolizing enzymes as well as to develop much more potent and specific inhibitors, the field of sphingolipids has recently taken a turn toward structural biology. The last decade has seen the structural determination of a number of sphingolipid enzymes and effector proteins. In these terms, one of the most complete arms of the sphingolipid pathway is the sphingosine-1-phosphate (S1P) arm. The structures of proteins involved in the function and regulation of S1P are being used to investigate further the regulation of said proteins as well as in the design and development of inhibitors as potential therapeutics. PMID:25923252

  6. Children with Emotional/Behavioral Problems and Their Family Structures.

    ERIC Educational Resources Information Center

    Lenhart, Tammy L.; Chudzinski, Julie

    This study investigated the family structures of 30 children (ages 7 to 18) with emotional/behavioral problems receiving treatment in a mental health agency. Traditional family structure was defined as a home in which both biological parents are present. Nontraditional family structures included: (1) single-parent families with one biological…

  7. [Individuals and their peers: a structural perspective].

    PubMed

    Schäfer, Mechthild; von Salisch, Maria

    2013-01-01

    Peer relationships are diverse in the sense that their degree of obligation, their intensity, their stability and even their number of participants vary. At the same time they have effects on the intraindividual and interindividual development of children and adolescents who tend to value them highly. Sociometric peer nominations provide one way of describing the complexity of peer relationships and of analyzing their various determinants. Peers are sources of information in the context of a defined system like a classroom in school. The consistency of this information (how many children like A and how many children like B), its reciprocity, and its stability are structural parameters that--in concert with other psychological constructs--may provide valuable cues and predictions about the optimal conditions for a positive peer socialization. The present article attempts to use these structural elements as the point of departure by navigating through the complexity, in order to delineate existing knowledge before the background of open questions and important question marks. PMID:23596897

  8. Exploring Teacher and School Resilience as a New Perspective to Solve Persistent Problems in the Educational Sector

    ERIC Educational Resources Information Center

    Schelvis, Roosmarijn M. C.; Zwetsloot, Gerard I. J. M.; Bos, Evelien H.; Wiezer, Noortje M.

    2014-01-01

    In this paper, we will explore the relevance, meaning and perspectives of teacher, team and school resilience. The central research questions are: does the concept of teacher, team and school resilience offer new and promising perspectives on persistent problems in the educational sector? And secondly; how can resilience at individual, team and…

  9. Supporting teachers who introduce curricular innovations into their classrooms: A problem-solving perspective

    NASA Astrophysics Data System (ADS)

    Yerushalmi, Edit; Eylon, Bat-Sheva

    2013-06-01

    When classroom teachers introduce curricular innovations that conflict with their former deeply rooted practices, the teachers themselves experience a process of change. One professional development framework intended to support this change is the customization workshop, in which teachers cooperatively customize innovations to their own classroom contexts, reflect on the strengths and weaknesses of classroom implementation, and refine their innovations. Two goals sometimes conflict in such workshops: developing teachers’ skills as reflective practitioners (process) and maintaining crucial characteristics of the original innovations (product). This paper explores how to meet both challenges using the insights from a perspective that provides a striking parallel: developing expertlike problem-solving skills (process) as well as conceptual understanding (product) in the physics classroom. We apply this perspective by (a) characterizing an expertlike approach to pedagogical problem solving in the context of customization workshops, (b) determining the nature of pedagogical problems best suited for developing such an expertlike approach, (c) suggesting how to design customization workshops that support teachers to develop an expertlike approach to pedagogical problem solving. In particular, we hypothesize that applying cognitive apprenticeship in customization workshops in a manner similar to its application in the teaching of expertlike problem solving in the physics classroom should effectively help teachers approach the pedagogical problem of customization in an expertlike manner. We support our hypothesis with an empirical study of three year-long cooperative customization workshops for physics teachers that differed in terms of mentoring approach. We examined the questions (a) under which mentoring approaches did teachers perform an expertlike pedagogical problem-solving process and (b) which practices and perceptions emerged through execution of this process?

  10. Incremental Validity and Informant Effect from a Multi-Method Perspective: Assessing Relations between Parental Acceptance and Children's Behavioral Problems.

    PubMed

    Izquierdo-Sotorrío, Eva; Holgado-Tello, Francisco P; Carrasco, Miguel Á

    2016-01-01

    This study examines the relationships between perceived parental acceptance and children's behavioral problems (externalizing and internalizing) from a multi-informant perspective. Using mothers, fathers, and children as sources of information, we explore the informant effect and incremental validity. The sample was composed of 681 participants (227 children, 227 fathers, and 227 mothers). Children's (40% boys) ages ranged from 9 to 17 years (M = 12.52, SD = 1.81). Parents and children completed both the Parental Acceptance Rejection/Control Questionnaire (PARQ/Control) and the check list of the Achenbach System of Empirically Based Assessment (ASEBA). Statistical analyses were based on the correlated uniqueness multitrait-multimethod matrix (model MTMM) by structural equations and different hierarchical regression analyses. Results showed a significant informant effect and a different incremental validity related to which combination of sources was considered. A multi-informant perspective rather than a single one increased the predictive value. Our results suggest that mother-father or child-father combinations seem to be the best way to optimize the multi-informant method in order to predict children's behavioral problems based on perceived parental acceptance. PMID:27242582

  11. Structural qualia: a solution to the hard problem of consciousness

    PubMed Central

    Loorits, Kristjan

    2014-01-01

    The hard problem of consciousness has been often claimed to be unsolvable by the methods of traditional empirical sciences. It has been argued that all the objects of empirical sciences can be fully analyzed in structural terms but that consciousness is (or has) something over and above its structure. However, modern neuroscience has introduced a theoretical framework in which also the apparently non-structural aspects of consciousness, namely the so called qualia or qualitative properties, can be analyzed in structural terms. That framework allows us to see qualia as something compositional with internal structures that fully determine their qualitative nature. Moreover, those internal structures can be identified which certain neural patterns. Thus consciousness as a whole can be seen as a complex neural pattern that misperceives some of its own highly complex structural properties as monadic and qualitative. Such neural pattern is analyzable in fully structural terms and thereby the hard problem is solved. PMID:24672510

  12. Analytic semigroups: Applications to inverse problems for flexible structures

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Rebnord, D. A.

    1990-01-01

    Convergence and stability results for least squares inverse problems involving systems described by analytic semigroups are presented. The practical importance of these results is demonstrated by application to several examples from problems of estimation of material parameters in flexible structures using accelerometer data.

  13. Invisible hand or fatherly hand? Problems of paternalism in the New Perspective on health.

    PubMed

    Weale, A

    1983-01-01

    This article examines the charge that the "New Perspective" on health (as exemplified by the Lalonde Report in Canada, by Prevention and Health in the United Kingdom) represents an abandonment of liberal principles in favor of a collectivist and paternalistic role for the state. It looks first at the problems confronting modern health policy, and at the reasoning behind the New Perspective's approach. It then explores whether and how the charge of paternalism applies to that approach, and just what such a charge implies. The article concludes with a discussion of the "liberal paternalist" viewpoint towards health policy, a viewpoint that combines respect for individual liberty with an interest in taking effective public action to improve the health status of modern populations. PMID:6841937

  14. Whither Ribosome Structure and Dynamics Research? (A Perspective).

    PubMed

    Frank, Joachim

    2016-09-11

    As high-resolution cryogenic electron microscopy (cryo-EM) structures of ribosomes proliferate, at resolutions that allow atomic interactions to be visualized, this article attempts to give a perspective on the way research on ribosome structure and dynamics may be headed, and particularly the new opportunities we have gained through recent advances in cryo-EM. It is pointed out that single-molecule FRET and cryo-EM form natural complements in the characterization of ribosome dynamics and transitions among equilibrating states of in vitro translational systems. PMID:27178840

  15. The Lunar Internal Structure Model: Problems and Solutions

    NASA Astrophysics Data System (ADS)

    Nefedyev, Yuri; Gusev, Alexander; Petrova, Natalia; Varaksina, Natalia

    The report is devoted the problems of the internal structure and gravitational field of the Moon. New data received from 14 newest instruments installed on low-orbit satellite Kaguya essentially enriched our knowledge of the Moon. Chinese satellite ChagE-1 and Indian Сhandrayan-1 have demonstrated strong potential of China and India in the field of lunar research and obtained new data on gravitational field, mascons, crust, and geochemical composition of the circumlunar space. Internal structure of the Moon: There are some essential arguments in favor of existence of a small-sized Moon’s core made of metallic iron alloyed with a small amount of sulfur and/or oxygen, and availability of hot viscous lower mantle. Structure of gravitational field of the Moon, determined by the comparison of high-precision trajectory measurements by Lunar Prospector (1998- 1999) with the results of laser altimetry obtained by Clementine (1994), as well as with data sets of laser ranging of the Moon (1970-2006), assumes the presence of a metal core. Interpretation of the polar moment value within the framework of chemical, thermal and density models of lunar crust and mantle informed conclusions about the weight and size of the core. LLR analysis of dissipation of rotation of the Moon points at two possible sources of dissipation: monthly solid-state inflows and liquid core, rotation of which differs from viscous-elastic mantle. Liquid (melted) core has its unique impact on the Moon’s rotation. In particular, there are two force moments due to topographical and phase interaction at the boundary between liquid core and elastic mantle (CMB). Liquid core can rotate independently from solid mantle Selenoid satellites (SS) open new and most perspective opportunities in the study of gravitational field and the Moon’s figure. SSs “Moon 10”, “Apollo”, “Clementine”, “Lunar Prospector” trajectory tracking data processing has allowed for identification of coefficients in

  16. Teaching problem solving through cooperative grouping. Part 2: Designing problems and structuring groups

    NASA Astrophysics Data System (ADS)

    Heller, Patricia; Hollabaugh, Mark

    1992-07-01

    A supportive environment based on cooperative grouping was developed to foster students' learning of an effective problem-solving strategy. Experiments to adapt the technique of cooperative grouping to physics problem solving were carried out in two diverse settings: a large introductory course at state university, and a small modern physics class at a community college. Groups were more likely to use an effective problem-solving strategy when given context-rich problems to solve than when given standard textbook problems. Well-functioning cooperative groups were found to result from specific structural and management procedures governing group members' interactions. Group size, the gender and ability composition of groups, seating arrangement, role assignment, textbook use, and group as well as individual testing were all found to contribute to the problem-solving performance of cooperative groups.

  17. Home care assistants’ perspectives on detecting mental health problems and promoting mental health among community-dwelling seniors with multimorbidity

    PubMed Central

    Grundberg, Åke; Hansson, Anna; Religa, Dorota; Hillerås, Pernilla

    2016-01-01

    Introduction Elderly people with multiple chronic conditions, or multimorbidity, are at risk of developing poor mental health. These seniors often remain in their homes with support from home care assistants (HCAs). Mental health promotion by HCAs needs to be studied further because they may be among the first to observe changes in clients’ mental health status. Aim To describe HCAs’ perspectives on detecting mental health problems and promoting mental health among homebound seniors with multimorbidity. Methods We applied a descriptive qualitative study design using semi-structured interviews. Content analyses were performed on five focus group interviews conducted in 2014 with 26 HCAs. Results Most HCAs stated that they were experienced in caring for clients with mental health problems such as anxiety, depression, sleep problems, and high alcohol consumption. The HCAs mentioned as causes, or risk factors, multiple chronic conditions, feelings of loneliness, and social isolation. The findings reveal that continuity of care and seniors’ own thoughts and perceptions were essential to detecting mental health problems. Observation, collaboration, and social support emerged as important means of detecting mental health problems and promoting mental health. Conclusion The HCAs had knowledge of risk factors, but they seemed insecure about which health professionals had the primary responsibility for mental health. They also seemed to have detected early signs of mental health problems, even though good personal knowledge of the client and continuity in home visits were crucial to do so. When it came to mental health promotion, the suggestions related to the aim of ending social isolation, decreasing feelings of loneliness, and increasing physical activity. The results indicate that the HCAs seemed dependent on supervision by district nurses and on care managers’ decisions to support the needed care, to schedule assignments related to the detection of mental health

  18. Algebraic multigrid methods applied to problems in computational structural mechanics

    NASA Technical Reports Server (NTRS)

    Mccormick, Steve; Ruge, John

    1989-01-01

    The development of algebraic multigrid (AMG) methods and their application to certain problems in structural mechanics are described with emphasis on two- and three-dimensional linear elasticity equations and the 'jacket problems' (three-dimensional beam structures). Various possible extensions of AMG are also described. The basic idea of AMG is to develop the discretization sequence based on the target matrix and not the differential equation. Therefore, the matrix is analyzed for certain dependencies that permit the proper construction of coarser matrices and attendant transfer operators. In this manner, AMG appears to be adaptable to structural analysis applications.

  19. Variational structure of inverse problems in wave propagation and vibration

    SciTech Connect

    Berryman, J.G.

    1995-03-01

    Practical algorithms for solving realistic inverse problems may often be viewed as problems in nonlinear programming with the data serving as constraints. Such problems are most easily analyzed when it is possible to segment the solution space into regions that are feasible (satisfying all the known constraints) and infeasible (violating some of the constraints). Then, if the feasible set is convex or at least compact, the solution to the problem will normally lie on the boundary of the feasible set. A nonlinear program may seek the solution by systematically exploring the boundary while satisfying progressively more constraints. Examples of inverse problems in wave propagation (traveltime tomography) and vibration (modal analysis) will be presented to illustrate how the variational structure of these problems may be used to create nonlinear programs using implicit variational constraints.

  20. Environmental Policies and Problems in Japan, China, and Hong Kong: Travel Perspectives.

    ERIC Educational Resources Information Center

    Therivel, Riki; Wrisberg, Mette

    1988-01-01

    Compared are some of the environmental planning policies and developmental policies of three regions of the Far East. Discusses the relationship between social structures and environmental problems such as pollution, erosion, waste disposal, and the uses of technology. (CW)

  1. The Association between Sleep Problems and Psychotic Symptoms in the General Population: A Global Perspective

    PubMed Central

    Koyanagi, Ai; Stickley, Andrew

    2015-01-01

    Study Objectives: To assess the prevalence of sleep problems and their association with psychotic symptoms using a global database. Design: Community-based cross-sectional study. Setting: Data were analyzed from the World Health Organization's World Health Survey (WHS), a population-based survey conducted in 70 countries between 2002 and 2004. Patients or Participants: 261,547 individuals aged ≥ 18 years from 56 countries. Interventions: N/A. Measurements and Results: The presence of psychotic symptoms in the past 12 months was established using 4 questions pertaining to positive symptoms from the psychosis screening module of the Composite International Diagnostic Interview. Sleep problems referred to severe or extreme sleep problems in the past 30 days. Multivariable logistic regression was used to estimate the associations. The overall prevalence of sleep problems was 7.6% and ranged from 1.6% (China) to 18.6% (Morocco). Sleep problems were associated with significantly higher odds for at least one psychotic symptom in the vast majority of countries. In the pooled sample, after adjusting for demographic factors, alcohol consumption, smoking, and chronic medical conditions, having sleep problems resulted in an odds ratio (OR) for at least one psychotic symptom of 2.41 (95% confidence interval [CI] 2.18–2.65). This OR was 1.59 (1.40–1.81) when further adjusted for anxiety and depression. Conclusions: A strong association between sleep problems and psychotic symptoms was observed globally. These results have clinical implications and serve as a basis for future studies to elucidate the causal association between psychotic symptoms and sleep problems. Citation: Koyanagi A, Stickley A. The association between sleep problems and psychotic symptoms in the general population: a global perspective. SLEEP 2015;38(12):1875–1885. PMID:26085291

  2. Structure-based virtual screening for drug discovery: a problem-centric review.

    PubMed

    Cheng, Tiejun; Li, Qingliang; Zhou, Zhigang; Wang, Yanli; Bryant, Stephen H

    2012-03-01

    Structure-based virtual screening (SBVS) has been widely applied in early-stage drug discovery. From a problem-centric perspective, we reviewed the recent advances and applications in SBVS with a special focus on docking-based virtual screening. We emphasized the researchers' practical efforts in real projects by understanding the ligand-target binding interactions as a premise. We also highlighted the recent progress in developing target-biased scoring functions by optimizing current generic scoring functions toward certain target classes, as well as in developing novel ones by means of machine learning techniques. PMID:22281989

  3. A Qualitative Approach to a Better Understanding of the Problems Underlying Drug Shortages, as Viewed from Belgian, French and the European Union's Perspectives.

    PubMed

    Bogaert, Petronille; Bochenek, Tomasz; Prokop, Anna; Pilc, Andrzej

    2015-01-01

    The problem of drug shortages has been reported worldwide, gaining prominence in multiple domains and several countries in recent years. The aim of the study was to analyze, characterise and assess this problem in Belgium and France, while also adopting a wider perspective from the European Union. A qualitative methodological approach was employed, including semi-structured interviews with the representatives of respective national health authorities, pharmaceutical companies and wholesalers, as well as hospital and community pharmacists. The research was conducted in early 2014. Four themes, which were identified through the interviews, were addressed in the paper, i.e. a) defining drug shortages, b) their dynamics and perception, c) their determinants, d) the role of the European and national institutions in coping with the problem. Three groups of determinants of drug shortages were identified throughout this study: manufacturing problems, distribution and supply problems, and problems related to economic aspects. Currently, the Member States of the European Union are striving to resolve the problem very much on their own, although a far more focused and dedicated collaboration may well prove instrumental in coping with drug shortages throughout Europe more effectively. To the best of the authors' knowledge, this is the first qualitative study to investigate the characteristics, key determinants, and the problem drivers of drug shortages, focusing on this particular group of countries, while also adopting the European Union's perspective. PMID:25942432

  4. A Qualitative Approach to a Better Understanding of the Problems Underlying Drug Shortages, as Viewed from Belgian, French and the European Union’s Perspectives

    PubMed Central

    Prokop, Anna; Pilc, Andrzej

    2015-01-01

    The problem of drug shortages has been reported worldwide, gaining prominence in multiple domains and several countries in recent years. The aim of the study was to analyze, characterise and assess this problem in Belgium and France, while also adopting a wider perspective from the European Union. A qualitative methodological approach was employed, including semi-structured interviews with the representatives of respective national health authorities, pharmaceutical companies and wholesalers, as well as hospital and community pharmacists. The research was conducted in early 2014. Four themes, which were identified through the interviews, were addressed in the paper, i.e. a) defining drug shortages, b) their dynamics and perception, c) their determinants, d) the role of the European and national institutions in coping with the problem. Three groups of determinants of drug shortages were identified throughout this study: manufacturing problems, distribution and supply problems, and problems related to economic aspects. Currently, the Member States of the European Union are striving to resolve the problem very much on their own, although a far more focused and dedicated collaboration may well prove instrumental in coping with drug shortages throughout Europe more effectively. To the best of the authors’ knowledge, this is the first qualitative study to investigate the characteristics, key determinants, and the problem drivers of drug shortages, focusing on this particular group of countries, while also adopting the European Union’s perspective. PMID:25942432

  5. Iraqi primary care system in Kurdistan region: providers’ perspectives on problems and opportunities for improvement

    PubMed Central

    2012-01-01

    Background As part of a comprehensive study on the primary health care system in Iraq, we sought to explore primary care providers’ perspectives about the main problems influencing the provision of primary care services and opportunities to improve the system. Methods A qualitative study based on four focus groups involving 40 primary care providers from 12 primary health care centres was conducted in Erbil governorate in the Iraqi Kurdistan region between July and October 2010. A topic guide was used to lead discussions and covered questions on positive aspects of and current problems with the primary care system in addition to the priority needs for its improvement. The discussions were fully transcribed and the qualitative data was analyzed by content analysis, followed by a thematic analysis. Results Problems facing the primary care system included inappropriate health service delivery (irrational use of health services, irrational treatment, poor referral system, poor infrastructure and poor hygiene), health workforce challenges (high number of specialists, uneven distribution of the health workforce, rapid turnover, lack of training and educational opportunities and discrepancies in the salary system), shortage in resources (shortage and low quality of medical supplies and shortage in financing), poor information technology and poor leadership/governance. The greatest emphasis was placed on poor organization of health services delivery, particularly the irrational use of health services and the related overcrowding and overload on primary care providers and health facilities. Suggestions for improving the system included application of a family medicine approach and ensuring effective planning and monitoring. Conclusions This study has provided a comprehensive understanding of the factors that negatively affect the primary care system in Iraq’s Kurdistan region from the perspective of primary care providers. From their experience, primary care providers

  6. The damper placement problem for large flexible space structures

    NASA Technical Reports Server (NTRS)

    Kincaid, Rex K.

    1992-01-01

    The damper placement problem for large flexible space truss structures is formulated as a combinatorial optimization problem. The objective is to determine the p truss members of the structure to replace with active (or passive) dampers so that the modal damping ratio is as large as possible for all significant modes of vibration. Equivalently, given a strain energy matrix with rows indexed on the modes and the columns indexed on the truss members, we seek to find the set of p columns such that the smallest row sum, over the p columns, is maximized. We develop a tabu search heuristic for the damper placement problems on the Controls Structures Interaction (CSI) Phase 1 Evolutionary Model (10 modes and 1507 truss members). The resulting solutions are shown to be of high quality.

  7. An Event-Based Solution to the Perspective-n-Point Problem

    PubMed Central

    Reverter Valeiras, David; Kime, Sihem; Ieng, Sio-Hoi; Benosman, Ryad Benjamin

    2016-01-01

    The goal of the Perspective-n-Point problem (PnP) is to find the relative pose between an object and a camera from a set of n pairings between 3D points and their corresponding 2D projections on the focal plane. Current state of the art solutions, designed to operate on images, rely on computationally expensive minimization techniques. For the first time, this work introduces an event-based PnP algorithm designed to work on the output of a neuromorphic event-based vision sensor. The problem is formulated here as a least-squares minimization problem, where the error function is updated with every incoming event. The optimal translation is then computed in closed form, while the desired rotation is given by the evolution of a virtual mechanical system whose energy is proven to be equal to the error function. This allows for a simple yet robust solution of the problem, showing how event-based vision can simplify computer vision tasks. The approach takes full advantage of the high temporal resolution of the sensor, as the estimated pose is incrementally updated with every incoming event. Two approaches are proposed: the Full and the Efficient methods. These two methods are compared against a state of the art PnP algorithm both on synthetic and on real data, producing similar accuracy in addition of being faster. PMID:27242412

  8. Teaching Mathematical Word Problem Solving: The Quality of Evidence for Strategy Instruction Priming the Problem Structure

    ERIC Educational Resources Information Center

    Jitendra, Asha K.; Petersen-Brown, Shawna; Lein, Amy E.; Zaslofsky, Anne F.; Kunkel, Amy K.; Jung, Pyung-Gang; Egan, Andrea M.

    2015-01-01

    This study examined the quality of the research base related to strategy instruction priming the underlying mathematical problem structure for students with learning disabilities and those at risk for mathematics difficulties. We evaluated the quality of methodological rigor of 18 group research studies using the criteria proposed by Gersten et…

  9. Measuring the impact and distress of health problems from the individual's perspective: development of the Perceived Impact of Problem Profile (PIPP)

    PubMed Central

    Pallant, Julie F; Misajon, RoseAnne; Bennett, Elizabeth; Manderson, Lenore

    2006-01-01

    Background The aim of this study was to develop and conduct preliminary validation of the Perceived Impact of Problem Profile (PIPP). Based on the biopsychosocial model of health and functioning, the PIPP was intended as a generic research and clinical measurement tool to assess the impact and distress of health conditions from the individuals' perspective. The ICF classification system was used to guide the structure of the PIPP with subscales included to assess impact on self-care, mobility, participation, relationships and psychological well-being. While the ICF focuses on the classification of objective health and health related status, the PIPP broadens this focus to address the individuals' subjective experience of their health condition. Methods An item pool of 23 items assessing both impact and distress on five key domains was generated. These were administered to 169 adults with mobility impairment. Rasch analysis using RUMM2020 was conducted to assess the psychometric properties of each set of items. Preliminary construct validation of the PIPP was performed using the EQ5D. Results For both the Impact and Distress scales of the PIPP, the five subscales (Self-care, Mobility, Participation, Relationships, and Psychological Well-being) showed adequate psychometric properties, demonstrating fit to the Rasch model. All subscales showed adequate person separation reliability and no evidence of differential item functioning for sex, age, educational level or rural vs urban residence. Preliminary validity testing using the EQ5D items provided support for the subscales. Conclusion This preliminary study, using a sample of adults with mobility impairment, provides support for the psychometric properties of the PIPP as a potential clinical and research measurement tool. The PIPP provides a brief, but comprehensive means to assess the key ICF components, focusing on the individuals' perspective of the impact and distress caused by their health condition. Further

  10. Understanding congestion in China's medical market: an incentive structure perspective.

    PubMed

    Sun, Zesheng; Wang, Shuhong; Barnes, Stephen R

    2016-04-01

    Congestion has become one of the most important factors leading to patient dissatisfaction and doctor-patient conflicts in the medical market of China. In this study, we explore the causes and effects of structural congestion in the Chinese medical market from an incentive structure perspective. Our analysis reveals that prior medical system reforms with price regulation in China have induced hospitals to establish incentives for capital-intensive investments, while ignoring human capital, and have driven medical staff and patients to higher-level hospitals, reinforcing an incentive structure in which congestion in higher-level hospitals and idle resources in lower-level hospitals coexist. The existing incentive structure has led to cost increases and degradation of human capital and specific factor effects. Recent reforms to reduce congestion in the Chinese medical market were not effective. Most of them had no impact on and did not involve the existing distorted incentive structure. Future reforms should consider rebalancing expectations for medical quality, free flow of human capital and price regulation reforms to rebuild a new incentive structure. PMID:26185181

  11. Structural DNA Nanotechnology: State of the Art and Future Perspective

    PubMed Central

    2015-01-01

    Over the past three decades DNA has emerged as an exceptional molecular building block for nanoconstruction due to its predictable conformation and programmable intra- and intermolecular Watson–Crick base-pairing interactions. A variety of convenient design rules and reliable assembly methods have been developed to engineer DNA nanostructures of increasing complexity. The ability to create designer DNA architectures with accurate spatial control has allowed researchers to explore novel applications in many directions, such as directed material assembly, structural biology, biocatalysis, DNA computing, nanorobotics, disease diagnosis, and drug delivery. This Perspective discusses the state of the art in the field of structural DNA nanotechnology and presents some of the challenges and opportunities that exist in DNA-based molecular design and programming. PMID:25029570

  12. Structural DNA nanotechnology: state of the art and future perspective.

    PubMed

    Zhang, Fei; Nangreave, Jeanette; Liu, Yan; Yan, Hao

    2014-08-13

    Over the past three decades DNA has emerged as an exceptional molecular building block for nanoconstruction due to its predictable conformation and programmable intra- and intermolecular Watson-Crick base-pairing interactions. A variety of convenient design rules and reliable assembly methods have been developed to engineer DNA nanostructures of increasing complexity. The ability to create designer DNA architectures with accurate spatial control has allowed researchers to explore novel applications in many directions, such as directed material assembly, structural biology, biocatalysis, DNA computing, nanorobotics, disease diagnosis, and drug delivery. This Perspective discusses the state of the art in the field of structural DNA nanotechnology and presents some of the challenges and opportunities that exist in DNA-based molecular design and programming. PMID:25029570

  13. Family Structure, Community Context, and Adolescent Problem Behaviors

    ERIC Educational Resources Information Center

    Hoffman, John P.

    2006-01-01

    A number of models have been proposed to explain the relationship between family structure and adolescent problem behaviors, including several that consider parent-child relations, family income, stress, and residential mobility. However, studies have not explored whether the different types of communities within which families reside affect the…

  14. Detection of structural deterioration and associated airline maintenance problems

    NASA Technical Reports Server (NTRS)

    Henniker, H. D.; Mitchell, R. G.

    1972-01-01

    Airline operations involving the detection of structural deterioration and associated maintenance problems are discussed. The standard approach to the maintenance and inspection of aircraft components and systems is described. The frequency of inspections and the application of preventive maintenance practices are examined. The types of failure which airline transport aircraft encounter and the steps taken to prevent catastrophic failure are reported.

  15. PARTI primitives for unstructured and block structured problems

    NASA Technical Reports Server (NTRS)

    Sussman, Alan; Saltz, Joel; Das, Raja; Gupta, S.; Mavriplis, Dimitri; Ponnusamy, Ravi; Crowley, Kay

    1992-01-01

    Described here is a set of primitives (PARTI) developed to efficiently execute unstructured and block structured problems on distributed memory parallel machines. We present experimental data from a 3-D unstructured Euler solver run on the Intel Touchstone Delta to demonstrate the usefulness of our methods.

  16. Data structures on data flow computers: implementations and problems

    SciTech Connect

    Samet, S.; Gokhale, M.

    1984-01-01

    This paper examines hybrid mechanisms which have been developed to solve the problem of implementing data structures on dataflow machines. These methods require that the data delivery system transmit a pointer to the structure rather than all the elements of the array. The array is then stored in a separate memory, and only the pointer travels on the arc. Schemes used by the Utah DDM, the MIT data flow machine, and the Manchester University machine are presented. Implications for the use of complex data structures on dataflow machines are also discussed. 13 references.

  17. Dynamic Programming for Structured Continuous Markov Decision Problems

    NASA Technical Reports Server (NTRS)

    Dearden, Richard; Meuleau, Nicholas; Washington, Richard; Feng, Zhengzhu

    2004-01-01

    We describe an approach for exploiting structure in Markov Decision Processes with continuous state variables. At each step of the dynamic programming, the state space is dynamically partitioned into regions where the value function is the same throughout the region. We first describe the algorithm for piecewise constant representations. We then extend it to piecewise linear representations, using techniques from POMDPs to represent and reason about linear surfaces efficiently. We show that for complex, structured problems, our approach exploits the natural structure so that optimal solutions can be computed efficiently.

  18. CALL FOR PAPERS: Special issue on the random search problem: trends and perspectives

    NASA Astrophysics Data System (ADS)

    da Luz, Marcos G. E.; Grosberg, Alexander Y.; Raposo, Ernesto P.; Viswanathan, Gandhi M.

    2008-11-01

    field. The subject can be approached from the perspective of different fields: ecology, networks, transport problems, molecular biology, etc. The study of the problem is particularly suited to the concepts and methods of statistical physics and stochastic processes; for example, fractals, random walks, anomalous diffusion. Discrete landscapes can be approached via graph theory, random lattices and complex networks. Such topics are regularly discussed in Journal of Physics A: Mathematical and Theoretical. All such aspects of the problem fall within the scope and focus of this special issue on the random search problem: trends and perspectives. Editorial policy All contributions to the special issue will be refereed in accordance with the refereeing policy of the journal. In particular, all research papers will be expected to be original work reporting substantial new results. The issue will also contain a number of review articles by invitation only. The Guest Editors reserve the right to judge whether a contribution fits the scope of the special issue. Guidelines for preparation of contributions We aim to publish the special issue in August 2009. To realize this, the DEADLINE for contributed papers is 15 January 2009. There is a page limit of 15 printed pages (approximately 9000 words) per contribution. For papers exceeding this limit, the Guest Editors reserve the right to request a reduction in length. Further advice on document preparation can be found at www.iop.org/Journals/jphysa. Contributions to the special issue should if possible be submitted electronically by web upload at www.iop.org/Journals/jphysa, or by email to jphysa@iop.org, quoting 'J. Phys. A Special Issue— Random Search Problem'. Please state whether the paper has been invited or is contributed. Submissions should ideally be in standard LaTeX form. Please see the website for further information on electronic submissions. Authors unable to submit electronically may send hard-copy contributions to

  19. Finite element solution of transient fluid-structure interaction problems

    NASA Technical Reports Server (NTRS)

    Everstine, Gordon C.; Cheng, Raymond S.; Hambric, Stephen A.

    1991-01-01

    A finite element approach using NASTRAN is developed for solving time-dependent fluid-structure interaction problems, with emphasis on the transient scattering of acoustic waves from submerged elastic structures. Finite elements are used for modeling both structure and fluid domains to facilitate the graphical display of the wave motion through both media. For the liquid, the use of velocity potential as the fundamental unknown results in a symmetric matrix equation. The approach is illustrated for the problem of transient scattering from a submerged elastic spherical shell subjected to an incident tone burst. The use of an analogy between the equations of elasticity and the wave equation of acoustics, a necessary ingredient to the procedure, is summarized.

  20. Assessment of structural analysis technology for elastic shell collapse problems

    NASA Technical Reports Server (NTRS)

    Knight, N. F., Jr.; Macy, S. C.; Mccleary, S. L.

    1989-01-01

    The prediction of the ultimate load carrying capability for compressively loaded shell structures is a challenging nonlinear analysis problem. Selected areas of finite element technology research and nonlinear solution technology are assessed. Herein, a finite element analysis procedure is applied to four shell collapse problems which have been used by computational structural mechanics researchers in the past. This assessment will focus on a number of different shell element formulations and on different approaches used to account for geometric nonlinearities. The results presented confirm that these aspects of nonlinear shell analysis can have a significant effect on the predicted nonlinear structural response. All analyses were performed using the CSM Testbed software system which allowed a convenient assessment of different element formulations with a consistent approach to solving the discretized nonlinear equations.

  1. [Between idealization and devaluation--problems and perspectives of theoretical analyses of female homo- and heterosexuality].

    PubMed

    Flaake, K

    1995-01-01

    Female homosexuality remains a controversial topic. Comparing psychoanalytic and sociological-feminist approaches to the phenomenon, the author points up clear theoretical distinctions between the two perspectives. Feminist authors tend towards an idealization of female homosexuality, while psychoanalysts display an inclination to devalue it as something pathological. However, the latent messages in both discourses have a number of points in common, traceable to a key problem they both have to come to grips with, the "lesbian complex". In lesbian relationships Flaake discerns a "third chance", an area not sanctioned by society, in which it is possible to re-attempt something left unattained in the early mother-daughter relationship: the appropriation of the female body. PMID:7480810

  2. A framework for solving ill-structured community problems

    NASA Astrophysics Data System (ADS)

    Keller, William Cotesworth

    A multifaceted protocol for solving ill-structured community problems has been developed. It embodies the lessons learned from the past by refining and extending features of previous models from the systems thinkers, and the fields of behavioral decision making and creative problem solving. The protocol also embraces additional features needed to address the unique aspects of community decision situations. The essential elements of the protocol are participants from the community, a problem-solving process, a systems picture, a facilitator, a modified Delphi method of communications, and technical expertise. This interdisciplinary framework has been tested by a quasi experiment with a real world community problem (the high cost of electrical power on Long Island, NY). Results indicate the protocol can enable members of the community to understand a complicated, ill-structured problem and guide them to action to solve the issue. However, the framework takes time (over one year in the test case) and will be inappropriate for crises where quick action is needed.

  3. MSClique: Multiple Structure Discovery through the Maximum Weighted Clique Problem

    PubMed Central

    Alquézar, René; Serratosa, Francesc; Moreno-Noguer, Francesc; Andrade-Cetto, Juan; González Ballester, Miguel Ángel

    2016-01-01

    We present a novel approach for feature correspondence and multiple structure discovery in computer vision. In contrast to existing methods, we exploit the fact that point-sets on the same structure usually lie close to each other, thus forming clusters in the image. Given a pair of input images, we initially extract points of interest and extract hierarchical representations by agglomerative clustering. We use the maximum weighted clique problem to find the set of corresponding clusters with maximum number of inliers representing the multiple structures at the correct scales. Our method is parameter-free and only needs two sets of points along with their tentative correspondences, thus being extremely easy to use. We demonstrate the effectiveness of our method in multiple-structure fitting experiments in both publicly available and in-house datasets. As shown in the experiments, our approach finds a higher number of structures containing fewer outliers compared to state-of-the-art methods. PMID:26766071

  4. MSClique: Multiple Structure Discovery through the Maximum Weighted Clique Problem.

    PubMed

    Sanroma, Gerard; Penate-Sanchez, Adrian; Alquézar, René; Serratosa, Francesc; Moreno-Noguer, Francesc; Andrade-Cetto, Juan; González Ballester, Miguel Ángel

    2016-01-01

    We present a novel approach for feature correspondence and multiple structure discovery in computer vision. In contrast to existing methods, we exploit the fact that point-sets on the same structure usually lie close to each other, thus forming clusters in the image. Given a pair of input images, we initially extract points of interest and extract hierarchical representations by agglomerative clustering. We use the maximum weighted clique problem to find the set of corresponding clusters with maximum number of inliers representing the multiple structures at the correct scales. Our method is parameter-free and only needs two sets of points along with their tentative correspondences, thus being extremely easy to use. We demonstrate the effectiveness of our method in multiple-structure fitting experiments in both publicly available and in-house datasets. As shown in the experiments, our approach finds a higher number of structures containing fewer outliers compared to state-of-the-art methods. PMID:26766071

  5. Mathematical theory of a relaxed design problem in structural optimization

    NASA Technical Reports Server (NTRS)

    Kikuchi, Noboru; Suzuki, Katsuyuki

    1990-01-01

    Various attempts have been made to construct a rigorous mathematical theory of optimization for size, shape, and topology (i.e. layout) of an elastic structure. If these are represented by a finite number of parametric functions, as Armand described, it is possible to construct an existence theory of the optimum design using compactness argument in a finite dimensional design space or a closed admissible set of a finite dimensional design space. However, if the admissible design set is a subset of non-reflexive Banach space such as L(sup infinity)(Omega), construction of the existence theory of the optimum design becomes suddenly difficult and requires to extend (i.e. generalize) the design problem to much more wider class of design that is compatible to mechanics of structures in the sense of variational principle. Starting from the study by Cheng and Olhoff, Lurie, Cherkaev, and Fedorov introduced a new concept of convergence of design variables in a generalized sense and construct the 'G-Closure' theory of an extended (relaxed) optimum design problem. A similar attempt, but independent in large extent, can also be found in Kohn and Strang in which the shape and topology optimization problem is relaxed to allow to use of perforated composites rather than restricting it to usual solid structures. An identical idea is also stated in Murat and Tartar using the notion of the homogenization theory. That is, introducing possibility of micro-scale perforation together with the theory of homogenization, the optimum design problem is relaxed to construct its mathematical theory. It is also noted that this type of relaxed design problem is perfectly matched to the variational principle in structural mechanics.

  6. Nonlinear Transient Problems Using Structure Compatible Heat Transfer Code

    NASA Technical Reports Server (NTRS)

    Hou, Gene

    2000-01-01

    The report documents the recent effort to enhance a transient linear heat transfer code so as to solve nonlinear problems. The linear heat transfer code was originally developed by Dr. Kim Bey of NASA Largely and called the Structure-Compatible Heat Transfer (SCHT) code. The report includes four parts. The first part outlines the formulation of the heat transfer problem of concern. The second and the third parts give detailed procedures to construct the nonlinear finite element equations and the required Jacobian matrices for the nonlinear iterative method, Newton-Raphson method. The final part summarizes the results of the numerical experiments on the newly enhanced SCHT code.

  7. [SENS is making sense - on the way to an innovative approach to structure Palliative Care problems].

    PubMed

    Eychmüller, Steffen

    2012-02-01

    Assessment in Palliative Care is a broad field trying to integrate various dimensions from physical, psychological, social and spiritual problems and suffering. Medical diagnosis alone may not successfully reflect this multidimensional aspects, as it may be true for nursing diagnosis. In addition, any assessment procedures in palliative care needs a) to be performed in an interprofessional way, i.e. integrating various perspectives, b) to avoid additional burden for the patient, and c) to allow repetitive longitudinal follow up in order to assess the outcomes of interventions. Derived from WHO definition of Palliative Care from 2002 we developed at our centre the problem- rather than diagnosis based SENS-Model and started its clinical implementation. This new tool to structure narratives from patients may facilitate not only to prioritize the various problems, but also to define tasks and responsibilities within the team including the evaluation of the intended benefit. Apart, SENS may help to avoid medicalisation and focus on pathological rather then salutogenetic interpretation. By this, SENS may develop towards a first problem - based ";classification and assessment system" in palliative care, possibly valuable for other chronic diseases and its multidimensional problems, too. PMID:22334197

  8. Transition of Library and Information Science Education in China: Problems and Perspective.

    ERIC Educational Resources Information Center

    Xiaoying, Dong

    1997-01-01

    Discusses problems in Chinese educational reform and trends in professional education. Based on the curriculum of 17 Chinese schools of library and information science, this article provides data on required courses, specialized elective courses, and nonspecialized courses to determine the state-of-the-art structure of the knowledge base and to…

  9. Potential structural material problems in a hydrogen energy system

    NASA Technical Reports Server (NTRS)

    Gray, H. R.; Nelson, H. G.; Johnson, R. E.; Mcpherson, W. B.; Howard, F. S.; Swisher, J. H.

    1976-01-01

    Potential structural material problems that may be encountered in the three components of a hydrogen energy system - production, transmission/storage, and utilization - have been identified. Hydrogen embrittlement, corrosion, oxidation, and erosion may occur during the production of hydrogen. Hydrogen embrittlement is of major concern during both transmission and utilization of hydrogen. Specific materials research and development programs necessary to support a hydrogen energy system are described. An awareness of probable shortages of strategic materials has been maintained in these suggested programs.

  10. Potential structural material problems in a hydrogen energy system

    NASA Technical Reports Server (NTRS)

    Gray, H. R.; Nelson, H. G.; Johnson, R. E.; Mcpherson, B.; Howard, F. S.; Swisher, J. H.

    1975-01-01

    Potential structural material problems that may be encountered in the three components of a hydrogen energy system - production, transmission/storage, and utilization - were identified. Hydrogen embrittlement, corrosion, oxidation, and erosion may occur during the production of hydrogen. Hydrogen embrittlement is of major concern during both transmission and utilization of hydrogen. Specific materials research and development programs necessary to support a hydrogen energy system are described.

  11. Expert-Like Performance in Everyday Domains: The Effects of Thinking Styles and Problem Structure on Problem-Solving Performance

    ERIC Educational Resources Information Center

    Gau, Roland

    2009-01-01

    An examination of research on expertise reveals potential gaps in current conceptualizations. Examinations of expertise often involve problems in ill-structured domains, which require abstract problem solving. Thus, conceptualizations of expertise are characterized by the use of relatively advanced, abstract problem-solving skills. Problems in…

  12. Recent advances, trends and new perspectives via enthalpy-based finite element formulations for applications to solidification problems

    NASA Technical Reports Server (NTRS)

    Tamma, Kumar K.; Namburu, Raju R.

    1990-01-01

    The present paper describes recent advances and trends in finite element developments and applications for solidification problems. In particular, in comparison to traditional methods of approach, new enthalpy-based architectures based on a generalized trapezoidal family of representations are presented which provide different perspectives, physical interpretation and solution architectures for effective numerical simulation of phase change processes encountered in solidification problems. Various numerical test models are presented and the results support the proposition for employing such formulations for general phase change applications.

  13. REVIEWS OF TOPICAL PROBLEMS: 21st century: what is life from the perspective of physics?

    NASA Astrophysics Data System (ADS)

    Ivanitskii, Genrikh R.

    2010-07-01

    The evolution of the biophysical paradigm over 65 years since the publication in 1944 of Erwin Schrödinger's What is Life? The Physical Aspects of the Living Cell is reviewed. Based on the advances in molecular genetics, it is argued that all the features characteristic of living systems can also be found in nonliving ones. Ten paradoxes in logic and physics are analyzed that allow defining life in terms of a spatial-temporal hierarchy of structures and combinatory probabilistic logic. From the perspective of physics, life can be defined as resulting from a game involving interactions of matter one part of which acquires the ability to remember the success (or failure) probabilities from the previous rounds of the game, thereby increasing its chances for further survival in the next round. This part of matter is currently called living matter.

  14. Employability Skills, Personal Qualities, and Early Employment Problems of Entry-Level Auditors: Perspectives from Employers, Lecturers, Auditors, and Students

    ERIC Educational Resources Information Center

    Lim, Yet-Mee; Lee, Teck Heang; Yap, Ching Seng; Ling, Chui Ching

    2016-01-01

    The authors examine the issue of employability of university accounting students from the perspectives of accounting firm employers, junior auditors, accounting lecturers, and accounting students. Areas of investigation include perceived importance of employability skills and desirable personal qualities; and early employment problems encountered…

  15. Rethinking policy perspectives on childhood stunting: time to formulate a structural and multifactorial strategy.

    PubMed

    Subramanian, S V; Mejía-Guevara, Iván; Krishna, Aditi

    2016-05-01

    Stunting and chronic undernutrition among children in South Asia remain a major unresolved global health issue. There are compelling intrinsic and moral reasons to ensure that children attain their optimal growth potential facilitated via promotion of healthy living conditions. Investments in efforts to ensure that children's growth is not faltered also have substantial instrumental benefits in terms of cognitive and economic development. Using the case of India, we critique three prevailing approaches to reducing undernutrition among children: an over-reliance on macroeconomic growth as a potent policy instrument, a disproportionate focus on interpreting undernutrition as a demand-side problem and an over-reliance on unintegrated single-factorial (one at a time) approaches to policy and research. Using existing evidence, we develop a case for support-led policy approach with a focus on integrated and structural factors to addressing the problem of undernutrition among children in India. Key messages Eliminating child undernutrition is important from an intrinsic perspective and offers considerable instrumental benefits to individual and society. Evidence suggests that an exclusive reliance on a growth-mediated strategy to eliminate stunting needs to be reconsidered, suggesting the need for a substantial support-led strategy. Interpreting and addressing undernutrition as a demand-side problem with proximal single-factorial interventions is futile. There is an urgent need to develop interventions that address the broader structural and upstream causes of child undernutrition. PMID:27187918

  16. Debates—Perspectives on socio-hydrology: Changing water systems and the "tyranny of small problems"—Socio-hydrology

    NASA Astrophysics Data System (ADS)

    Sivapalan, Murugesu

    2015-06-01

    We are well and truly in the Anthropocene. Humans can no longer be considered as mere external drivers or boundary conditions in the hydrologic systems we study. The interactions and feedbacks between human actions and water cycle dynamics on the planet, combined with the evolution of human norms/values in relation to water, are throwing up a range of emergent "big problems." Understanding and offering sustainable solutions to these "big problems" require a broadening of hydrologic science to embrace the perspectives of both social and natural scientists. The new science of socio-hydrology was introduced with this in mind, yet faces major challenges due to the wide gulf that separates the knowledge foundations and methodologies of natural and social sciences. Yet, the benefits of working together are enormous, including through adoption of natural science methods for social science problems, and vice versa. Bringing together the perspectives of both social and natural scientists dealing with water is good for hydrologic science, having the salutary effect of revitalizing it as use-inspired basic science. It is good for management too, in that the broader, holistic perspectives provided by socio-hydrology can help recognize potential "big" problems that may otherwise be unforeseen and, equally, identify potential "alternative" solutions to otherwise intractable problems.

  17. The Influence of Family Structure, the TPH2 G-703T and the 5-HTTLPR Serotonergic Genes upon Affective Problems in Children Aged 10-14 Years

    ERIC Educational Resources Information Center

    Nobile, Maria; Rusconi, Marianna; Bellina, Monica; Marino, Cecilia; Giorda, Roberto; Carlet, Ombretta; Vanzin, Laura; Molteni, Massimo; Battaglia, Marco

    2009-01-01

    Background: Both genetic and psychosocial risk factors influence the risk for depression in development. While the impacts of family structure and of serotonergic polymorphisms upon individual differences for affective problems have been investigated separately, they have never been considered together in a gene-environment interplay perspective.…

  18. Intriguing structures in iterative maps motivated by N-body problem

    NASA Astrophysics Data System (ADS)

    Mittal, Ashok Kumar; Gupta, Ashok Kumar

    2011-03-01

    Conventional approaches to modeling any system try to incorporate increasingly realistic features into the model, thereby making it more and more complex. An opposite approach seeks to build simpler and simpler conceptual models capable of capturing some observed features of a system. This trend began with Lorenz, who simplified models of the atmosphere to obtain the Lorenz model consisting of a system of only three equations. Despite the simplicity of these equations, this system displayed surprisingly rich properties, and has been used as a conceptual model in diverse disciplines. Poincare maps help study ordinary differential equations from a qualitative perspective. Several investigators like Henon and Feigenbaum followed this simplification approach. Instead of investigating Poincare maps of realistic systems, they, along with several others, investigated simple maps for their own sake. Despite lack of realism, this approach proved to be very fruitful. A map, as simple as the Logistic map, became an important conceptual modeling paradigm. It provided a tool for understanding bifurcation routes to chaos, which were verified experimentally through various experiments in diverse fields. Coupled map lattices (CML) help explore partial differential equations (PDE). Further simplification led to the introduction of Cellular Automata (CA). These fields continue to be explored with vigor and have given rise to a rich body of knowledge, conceptually useful over a wide spectrum of disciplines. In this paper, we follow the simplification approach for modeling the N-body problem. N-body simulations, say in Gravitation, give rise to filamentary structures. Such structures are observed in the actual observed Galactic distribution. The mechanism for creation of such structures is not well understood. We present a simple iterative dynamical model, motivated by the N-body problem, which, though unrealistic, produces such filamentary structures. This model also exhibits a

  19. Consumption, Ecological Footprints and Global Inequality: A Lesson in Individual and Structural Components of Environmental Problems

    ERIC Educational Resources Information Center

    Obach, Brian K.

    2009-01-01

    As evidence of the growing ecological crisis mounts, it is imperative that sociologists speak to this social problem and incorporate a sociological perspective on environmental issues into the curriculum. Central to understanding how social issues relate to environmental problems is an examination of the ties between consumption and its ecological…

  20. Time-limited, structured youth mentoring and adolescent problem behaviors

    PubMed Central

    Haddock, Shelley A.; Zimmerman, Toni S.; Henry, Kimberly L.; Krafchick, Jennifer L.; Youngblade, Lise M.

    2015-01-01

    Youth mentoring can have a profound impact on the lives of high-risk youth. This study presents the Campus Corps program, a time-limited (12-week), structured mentoring program for high-risk youth (ages 11–18), and results from a quasi-experimental pilot evaluation. Baseline and post-intervention problem behavior data from 315 offending youth were used in multiple regression analyses. After accounting for baseline group differences, pre-intervention scores, and demographic covariates, Campus Corps participants (n=187, 63.1% male) reported less engagement in problem behavior, lower acceptance of problem behavior, and greater sense of autonomy from marijuana use post-intervention than participants in the comparison condition (n=128, 66.4% male). Conversely, post-intervention group differences were not observed for peer refusal skills or autonomy from alcohol use. A description of the Campus Corps program design and supplemental preliminary findings contribute to the growing knowledge base of youth mentoring program designs and outcomes. PMID:26640362

  1. On path-following methods for structural failure problems

    NASA Astrophysics Data System (ADS)

    Stanić, Andjelka; Brank, Boštjan; Korelc, Jože

    2016-08-01

    We revisit the consistently linearized path-following method that can be applied in the nonlinear finite element analysis of solids and structures in order to compute a solution path. Within this framework, two constraint equations are considered: a quadratic one (that includes as special cases popular spherical and cylindrical forms of constraint equation), and another one that constrains only one degree-of-freedom (DOF), the critical DOF. In both cases, the constrained DOFs may vary from one solution increment to another. The former constraint equation is successful in analysing geometrically nonlinear and/or standard inelastic problems with snap-throughs, snap-backs and bifurcation points. However, it cannot handle problems with the material softening that are computed e.g. by the embedded-discontinuity finite elements. This kind of problems can be solved by using the latter constraint equation. The plusses and minuses of the both presented constraint equations are discussed and illustrated on a set of numerical examples. Some of the examples also include direct computation of critical points and branch switching. The direct computation of the critical points is performed in the framework of the path-following method by using yet another constraint function, which is eigenvector-free and suited to detect critical points.

  2. Internal structure of oceanic lithosphere: A perspective from tectonic windows

    NASA Astrophysics Data System (ADS)

    Karson, Jeffrey A.

    Major faulted escarpments on the seafloor provide "tectonic windows" into oceanic crust and upper mantle. Direct observations in these settings reveal that the spatial arrangement, internal structure, and contacts between major rock units are significantly more complex than commonly anticipated on the basis of seismic studies and ophiolite analogs. From this perspective, a stratiform, ophiolite-like sequence of rock units, including basaltic volcanic rocks, sheeted diabase dike complex, isotropic and layered gabbroic and ultramafic rocks over upper mantle peridotites—all separated by generally horizontal contacts, may be much less common in the oceanic lithosphere than generally thought. Conversely, documented examples of large outcrop areas (tens of kilometers across) that lack the ophiolite-like sequence or that contain structures that do not conform to the ophiolite model call into question the basic assumptions made in the reconstruction and interpretation of ophiolite complexes. Historically, the stratiform ophiolite architecture has been the basis for inferences of the interaction between tectonism and magmatism at mid-ocean ridge spreading centers. A growing number of constraints on geological relations along seafloor escarpments hint at much broader range of interactions between tectonic deformation and magmatic construction. Along slow-spreading ridges, the magma budget (volume of magma per unit plate separation) is highly variable, giving rise to a wide range of morphologic and geologic features along wide rift valleys. The diversity of crustal architectures and internal structures seen in tectonic windows is correspondingly large. Although it is possible that a relatively simple, layered ophiolite-like crust develops in regions of relatively high magma budget (Reykjanes Ridge, Azores region, etc.), more complex structures that differ from those of stratiform ophiolites are present where lower magma budgets prevail. Significant deviations from a simple

  3. Evolutionary perspectives of telomerase RNA structure and function.

    PubMed

    Podlevsky, Joshua D; Chen, Julian J-L

    2016-08-01

    Telomerase is the eukaryotic solution to the 'end-replication problem' of linear chromosomes by synthesising the highly repetitive DNA constituent of telomeres, the nucleoprotein cap that protects chromosome termini. Functioning as a ribonucleoprotein (RNP) enzyme, telomerase is minimally composed of the highly conserved catalytic telomerase reverse transcriptase (TERT) and essential telomerase RNA (TR) component. Beyond merely providing the template for telomeric DNA synthesis, TR is an innate telomerase component and directly facilitates enzymatic function. TR accomplishes this by having evolved structural elements for stable assembly with the TERT protein and the regulation of the telomerase catalytic cycle. Despite its prominence and prevalence, TR has profoundly diverged in length, sequence, and biogenesis pathway among distinct evolutionary lineages. This diversity has generated numerous structural and mechanistic solutions for ensuring proper RNP formation and high fidelity telomeric DNA synthesis. Telomerase provides unique insights into RNA and protein coevolution within RNP enzymes. PMID:27359343

  4. Representation and constraints: the inverse problem and the structure of visual space.

    PubMed

    Hatfield, Gary

    2003-11-01

    Visual space can be distinguished from physical space. The first is found in visual experience, while the second is defined independently of perception. Theorists have wondered about the relation between the two. Some investigators have concluded that visual space is non-Euclidean, and that it does not have a single metric structure. Here it is argued (1) that visual space exhibits contraction in all three dimensions with increasing distance from the observer, (2) that experienced features of this contraction (including the apparent convergence of lines in visual experience that are produced from physically parallel stimuli in ordinary viewing conditions) are not the same as would be the experience of a perspective projection onto a frontoparallel plane, and (3) that such contraction is consistent with size constancy. These properties of visual space are different from those that would be predicted if spatial perception resulted from the successful solution of the inverse problem. They are consistent with the notion that optical constraints have been internalized. More generally, they are also consistent with the notion that visual spatial structures bear a resemblance relation to physical spatial structures. This notion supports a type of representational relation that is distinct from mere causal correspondence. The reticence of some philosophers and psychologists to discuss the structure of phenomenal space is diagnosed in terms of the simple materialism and the functionalism of the 1970s and 1980s. PMID:14670704

  5. Interactions in Bacterial Biofilm Development: A Structural Perspective

    PubMed Central

    Garnett, James A; Matthews, Steve

    2012-01-01

    A community-based life style is the normal mode of growth and survival for many bacterial species. These cellular accretions or biofilms are initiated upon recognition of solid phases by cell surface exposed adhesive moieties. Further cell-cell interactions, cell signalling and bacterial replication leads to the establishment of dense populations encapsulated in a mainly self-produced extracellular matrix; this comprises a complex mixture of macromolecules. These fascinating architectures protect the inhabitants from radiation damage, dehydration, pH fluctuations and antimicrobial compounds. As such they can cause bacterial persistence in disease and problems in industrial applications. In this review we discuss the current understandings of these initial biofilm-forming processes based on structural data. We also briefly describe latter biofilm maturation and dispersal events, which although lack high-resolution insights, are the present focus for many structural biologists working in this field. Finally we give an overview of modern techniques aimed at preventing and disrupting problem biofilms. PMID:23305361

  6. Symplectic structures related with higher order variational problems

    NASA Astrophysics Data System (ADS)

    Kijowski, Jerzy; Moreno, Giovanni

    2015-06-01

    In this paper, we derive the symplectic framework for field theories defined by higher order Lagrangians. The construction is based on the symplectic reduction of suitable spaces of iterated jets. The possibility of reducing a higher order system of partial differential equations to a constrained first-order one, the symplectic structures naturally arising in the dynamics of a first-order Lagrangian theory, and the importance of the Poincaré-Cartan form for variational problems, are all well-established facts. However, their adequate combination corresponding to higher order theories is missing in the literature. Here we obtain a consistent and truly finite-dimensional canonical formalism, as well as a higher order version of the Poincaré-Cartan form. In our exposition, the rigorous global proofs of the main results are always accompanied by their local coordinate descriptions, indispensable to work out practical examples.

  7. Structural approaches to spin glasses and optimization problems

    NASA Astrophysics Data System (ADS)

    de Sanctis, Luca

    We introduce the concept of Random Multi-Overlap Structure (RaMOSt) as a generalization of the one introduced by M. Aizenman et al. for non-diluted spin glasses. We use this concept to find generalized bounds for the free energy of the Viana-Bray model of diluted spin glasses and to formulate and prove the Extended Variational Principle that implicitly provides the free energy of the model. Then we exhibit a theorem for the limiting RaMOSt, analogous to the one found by F. Guerra for the Sherrington-Kirkpatrick model, that describes some stability properties of the model. We also show how our technique can be used to prove the existence of the thermodynamic limit of the free energy. We then propose an ultrametric breaking of replica symmetry for diluted spin glasses in the framework of Random Multi-Overlap Structures (RaMOSt). Such a proposal is closer to the Parisi theory for non-diluted spin glasses than the theory based on the iterative approach. Our approach allows to formulate an ansatz in which the Broken Replica Symmetry trial function depends on a set of numbers, over which one has to take the infimum (as opposed to a nested chain of probabilty distributions). Our scheme suggests that the order parameter is determined by the probability distribution of the multi-overlap in a similar sense as in the non-diluted case, and it is not necessarily a functional. Such results are then extended to the K-SAT and p-XOR-SAT optimization problems, and to the spherical mean field spin glass. The ultrametric structure exhibits a factorization property similar to the one of the optimal structures for the Viana-Bray model. The present work paves the way to a revisited Parisi theory for diluted spin systems. Moreover, it emphasizes some structural analogies among different models, which also seem to be plausible for models that still escape good mathematical control. This structural analysis seems quite promising both mathematically and physically.

  8. Solving Optimal Control Problems by Exploiting Inherent Dynamical Systems Structures

    NASA Astrophysics Data System (ADS)

    Flaßkamp, Kathrin; Ober-Blöbaum, Sina; Kobilarov, Marin

    2012-08-01

    Computing globally efficient solutions is a major challenge in optimal control of nonlinear dynamical systems. This work proposes a method combining local optimization and motion planning techniques based on exploiting inherent dynamical systems structures, such as symmetries and invariant manifolds. Prior to the optimal control, the dynamical system is analyzed for structural properties that can be used to compute pieces of trajectories that are stored in a motion planning library. In the context of mechanical systems, these motion planning candidates, termed primitives, are given by relative equilibria induced by symmetries and motions on stable or unstable manifolds of e.g. fixed points in the natural dynamics. The existence of controlled relative equilibria is studied through Lagrangian mechanics and symmetry reduction techniques. The proposed framework can be used to solve boundary value problems by performing a search in the space of sequences of motion primitives connected using optimized maneuvers. The optimal sequence can be used as an admissible initial guess for a post-optimization. The approach is illustrated by two numerical examples, the single and the double spherical pendula, which demonstrates its benefit compared to standard local optimization techniques.

  9. Rigid Structure from Motion from a Blind Source Separation Perspective

    PubMed Central

    Fortuna, Jeff

    2013-01-01

    We present an information theoretic approach to define the problem of structure from motion (SfM) as a blind source separation one. Given that for almost all practical joint densities of shape points, the marginal densities are non-Gaussian, we show how higher-order statistics can be used to provide improvements in shape estimates over the methods of factorization via Singular Value Decomposition (SVD), bundle adjustment and Bayesian approaches. Previous techniques have either explicitly or implicitly used only second-order statistics in models of shape or noise. A further advantage of viewing SfM as a blind source problem is that it easily allows for the inclusion of noise and shape models, resulting in Maximum Likelihood (ML) or Maximum a Posteriori (MAP) shape and motion estimates. A key result is that the blind source separation approach has the ability to recover the motion and shape matrices without the need to explicitly know the motion or shape pdf. We demonstrate that it suffices to know whether the pdf is sub-or super-Gaussian (i.e., semi-parametric estimation) and derive a simple formulation to determine this from the data. We provide extensive experimental results on synthetic and real tracked points in order to quantify the improvement obtained from this technique. PMID:23682206

  10. An embodied perspective on expertise in solving the problem of making a geologic map

    NASA Astrophysics Data System (ADS)

    Callahan, Caitlin Norah

    The task of constructing a geologic map is a cognitively and physically demanding field-based problem. The map produced is understood to be an individual's two-dimensional interpretation or mental model of the three-dimensional underlying geology. A popular view within the geoscience community is that teaching students how to make a geologic map is valuable for preparing them to deal with disparate and incomplete data sets, for helping them develop problem-solving skills, and for acquiring expertise in geology. Few previous studies have focused specifically on expertise in geologic mapping. Drawing from literature related to expertise, to problem solving, and to mental models, two overarching research questions were identified: How do geologists of different levels of expertise constrain and solve an ill-structured problem such as making a geologic map? How do geologists address the uncertainties inherent to the processes and interpretations involved in solving a geologic mapping problem? These questions were answered using a methodology that captured the physical actions, expressed thoughts, and navigation paths of geologists as they made a geologic map. Eight geologists, from novice to expert, wore a head-mounted video camera with an attached microphone to record those actions and thoughts, creating "video logs" while in the field. The video logs were also time-stamped, which allowed the visual and audio data to be synchronized with the GPS data that tracked participants' movements in the field. Analysis of the video logs yielded evidence that all eight participants expressed thoughts that reflected the process of becoming mentally situated in the mapping task (e.g. relating between distance on a map and distance in three-dimensional space); the prominence of several of these early thoughts waned in the expressed thoughts later in the day. All participants collected several types of data while in the field; novices, however, did so more continuously throughout

  11. Adult Perspectives on Behavior and Emotional Problems in African American Children.

    ERIC Educational Resources Information Center

    Lambert, Michael Canute; Puig, Marieva; Lyubansky, Mikhail; Rowan, George T.; Winfrey, Tyrone

    2001-01-01

    Using vignettes describing African American children with internalizing versus externalizing problems, parents, teachers, and clinicians judged problem seriousness, prognosis, etiology, referral, and intervention needs. Opinions differed widely among groups, particularly on judgements about children with externalizing problems. More clinicians…

  12. How Students "Unpack" the Structure of a Word Problem: Graphic Representations and Problem Solving

    ERIC Educational Resources Information Center

    Edens, Kellah; Potter, Ellen

    2008-01-01

    This research investigated how fourth and fifth grade students spontaneously "unpacked" a word problem when generating a graphic representation to aid in problem solution. Relationships among the type of graphic representation produced, spatial visualization, drawing ability, gender, and problem solving also were examined and described.…

  13. The population problem in Turkey (as seen from the perspective of a foreign donor).

    PubMed

    Holzhausen, W

    1987-01-01

    From the perspective of the UN Fund for Population Activities, Turkey has a population problem of some magnitude. In 1987 the population reached 50 million, up from 25 million in 1957. Consistent with world trends, the population growth rate in Turkey declined from 2.5% between 1965-73 to 2.2% between 1973-84; it is expected to further decrease to 2.0% between 1980 and 2000. This is due primarily to a marked decline of the crude birthrate from 41/1000 in 1965 to 30/1000 in 1984. These effects have been outweighed by a more dramatic decline in the death rate from 14/1000 in 1965 to 9/1000 in 1984. Assuming Turkey to reach a Net Reproduction Rate of 1 by 2010, the World Bank estimates Turkey's population to reach some 109 million by the middle of the 21st century. The population could reach something like 150 million in the mid-21st century. Some significant progress has been made in Turkey in recent years in the area of family planning. Yet, some policy makers do not seem fully convinced of the urgency of creating an ever-increasing "awareness" among the population and of the need for more forceful family planning strategies. Government allocations for Maternal and Child Health and Family Planning (MCH/FP) services continue to be insufficient to realize a major breakthrough in curbing the population boom in the foreseeable future. Most foreign donors do not consider Turkey a priority country. It is believed to have sufficient expertise in most fields and to be able to raise most of the financial resources it needs for development. The UNFPA is the leading donor in the field of family planning, spending some US $800,000 at thi time. Foreign inputs into Turkey's family planning program are modest, most likely not exceeding US $1 million/year. Government expenditures are about 10 times higher. This independence in decision making is a positive factor. Turkey does not need to consider policy prescriptions that foreign donors sometimes hold out to recipients of aid. It

  14. Effects of a Problem-Based Structure of Physics Contents on Conceptual Learning and the Ability to Solve Problems

    ERIC Educational Resources Information Center

    Becerra-Labra, Carlos; Gras-Marti, Albert; Torregrosa, Joaquin Martinez

    2012-01-01

    A model of teaching/learning is proposed based on a "problem-based structure" of the contents of the course, in combination with a training in paper and pencil problem solving that emphasizes discussion and quantitative analysis, rather than formulae plug-in. The aim is to reverse the high failure and attrition rate among engineering…

  15. Incremental Validity and Informant Effect from a Multi-Method Perspective: Assessing Relations between Parental Acceptance and Children’s Behavioral Problems

    PubMed Central

    Izquierdo-Sotorrío, Eva; Holgado-Tello, Francisco P.; Carrasco, Miguel Á.

    2016-01-01

    This study examines the relationships between perceived parental acceptance and children’s behavioral problems (externalizing and internalizing) from a multi-informant perspective. Using mothers, fathers, and children as sources of information, we explore the informant effect and incremental validity. The sample was composed of 681 participants (227 children, 227 fathers, and 227 mothers). Children’s (40% boys) ages ranged from 9 to 17 years (M = 12.52, SD = 1.81). Parents and children completed both the Parental Acceptance Rejection/Control Questionnaire (PARQ/Control) and the check list of the Achenbach System of Empirically Based Assessment (ASEBA). Statistical analyses were based on the correlated uniqueness multitrait-multimethod matrix (model MTMM) by structural equations and different hierarchical regression analyses. Results showed a significant informant effect and a different incremental validity related to which combination of sources was considered. A multi-informant perspective rather than a single one increased the predictive value. Our results suggest that mother–father or child–father combinations seem to be the best way to optimize the multi-informant method in order to predict children’s behavioral problems based on perceived parental acceptance. PMID:27242582

  16. Problems in understanding the structure and assembly of viruses

    SciTech Connect

    King, J.

    1997-12-01

    Though viruses infect the cells of all groups of animals, plants, and microorganisms, their structures follow a limited number of general themes; spherical or cylindrical shells built of hundreds of repeated protein subunits enclosing a nucleic acid - DNA or RNA - genome. Since the 1960s it has been known that the protein shells of spherical viruses in fact conform to icosahedral symmetry or to subtle deviations from icosahedral symmetry. The construction of the shell lattices and the transformations they go through in the different stages of the viral life cycle are not fully understood. The shells contain the nucleic in a highly condensed state, of unknown coiling/organization. Features of the well studied bacterial viruses will be reviewed, with examples from adenoviruses, herpesviruses, poliovirus, and HIV. The emergence of new viral disease has led to increased interest in the development of agents which interfere with virus reproduction at the level of the assembly or function of the organized particle. Recently computational approaches to the problem of virus assembly have made important contributions to clarifying shell assembly processes. 1 ref.

  17. Practice Constraints, Behavioral Problems, and Dementia Care: Primary Care Physicians’ Perspectives

    PubMed Central

    Hinton, Ladson; Reddy, Geetha; Flores, Yvette; Kravitz, Richard L.; Barker, Judith C.

    2007-01-01

    Objectives To examine how practice constraints contribute to barriers in the health care of persons with dementia and their families, particularly with respect to behavioral aspects of care. Design Cross-sectional qualitative interview study of primary care physicians. Setting Physicians’ offices. Participants Forty primary care physicians in Northern California. Measurements Open-ended interviews lasted 30–60 minutes and were structured by an interview guide covering clinician background and practice setting, clinical care of a particular patient, and general approach to managing patients with AD or dementia. Interviews were transcribed and themes reflecting constraints of practice were identified through a systematic coding process. Results Recurring themes (i.e., those present in ≥25% of physician interviews) included insufficient time, difficulty in accessing and communicating with specialists, low reimbursement, poor connections with community social service agencies, and lack of interdisciplinary teams. Physician narratives suggest that these constraints may lead to delayed detection of behavior problems, “reactive” as opposed to proactive management of dementia, and increased reliance on pharmacological rather than psychosocial approaches. Conclusion Physicians often feel challenged in caring for dementia patients, particularly those who are more behaviorally complex, because of time and reimbursement constraints as well as other perceived barriers. Our results suggest that more effective educational interventions (for families and physicians) and broader structural changes are needed to better meet the needs of the elderly with dementia and their families now and in the future. Without these changes, dementia care is likely to continue to fall short. PMID:17823840

  18. The Space Physics ``Data Problem'' from the Perspectives of Different Stakeholders (Invited)

    NASA Astrophysics Data System (ADS)

    Donovan, E. F.

    2010-12-01

    Researchers, the PIs of VOs, and funding agencies frequently refer to an overarching “the data problem”. The Heliophysical Data Environment and other programs in the US and around the world have been put in place to address this issue. The data environment in space physics has evolved significantly in the last decade, and as a result there has been a dramatic and definitely positive increase in the effectiveness of systems for delivery of data to the research community. This has manifested itself in the form of in general much shorter (frequently less than a day) times between observation and the availability of scientific data products, greater uniformity in and long-term stability of file types and structures, the implementation of metadata standards, the establishment of remarkably effective summary plots and web-based browsing tools, and the growing availability of software that makes working with the scientific data products much easier than it used to be. Still, there are issues related to data and data services that need to be revisited as the data environment continues to evolve. Foremost in my mind is a sense that from the perspectives of funding agencies, producers of different types of data, and data users there is certainly not one “data problem”. For example, as a general rule funding agencies want data widely used, while university researchers who are producing data want to lead discovery-type research that uses that data in some key way. The PI of a big project usually benefits optimally if the data is totally open and widely utilized, while the interests of a grad student carrying out a project that centers in some way on data are often best served by a possibly years-long period during which access to that specific data is not open to the broader community. Novice or one-time users of a type of data are often best served by a web-based tool that will make a straightforward plot for them, while expert users usually just want access to a

  19. The Use of Video Cases in a Multimedia Learning Environment for Facilitating High School Students' Inquiry into a Problem from Varying Perspectives

    NASA Astrophysics Data System (ADS)

    Zydney, Janet Mannheimer; Grincewicz, Amy

    2011-12-01

    This study investigated the connection between the use of video cases within a multimedia learning environment and students' inquiry into a socio-scientific problem. The software program was designed based on principles from the Cognitive Flexibility Theory (CFT) and incorporated video cases of experts with differing perspectives. Seventy-nine 10th-grade students in an urban high school participated in this study. After watching the expert videos, students generated investigative questions and reflected on how their ideas changed over time. This study found a significant correlation between the time students spent watching the expert videos and their ability to consider the problem's perspectives as well as their ability to integrate these perspectives within their questions. Moreover, problem-solving ability and time watching the videos were detected as possible influential predictors of students' consideration of the problem's perspectives within their questions. Although students watched all video cases in equivalent ways, one of the video cases, which incorporated multiple perspectives as opposed to just presenting one perspective, appeared most influential in helping students integrate the various perspectives into their own thinking. A qualitative analysis of students' reflections indicated that many students appreciated the complexity, authenticity, and ethical dimensions of the problem. It also revealed that while the majority of students thought critically about the problem, some students still had naïve or simplistic ways of thinking. This study provided some preliminary evidence that offering students the opportunity to watch videos of different perspectives may influence them to think in alternative ways about a complex problem.

  20. Promoting Issues-Based STSE Perspectives in Science Teacher Education: Problems of Identity and Ideology

    ERIC Educational Resources Information Center

    Pedretti, Erminia G.; Bencze, Larry; Hewitt, Jim; Romkey, Lisa; Jivraj, Ashifa

    2008-01-01

    Although science, technology, society and environment (STSE) education has gained considerable force in the past few years, it has made fewer strides in practice. We suggest that "science" teacher identity plays a role in the adoption of STSE perspectives. Simply put, issues-based STSE education challenges traditional images of a science teacher…

  1. The Problem of the Pyramid or Egyptian Mathematics from a Postmodern Perspective

    ERIC Educational Resources Information Center

    Shutler, Paul M. E.

    2009-01-01

    We consider Egyptian mathematics from a postmodern perspective, by which we mean suspending judgement as to strict correctness in order to appreciate the genuine mathematical insights which they did have in the context in which they were working. In particular we show that the skill which the Egyptians possessed of obtaining the general case from…

  2. When Your "Problem" Becomes Mine: Adult Female Siblings' Perspectives of Having a Brother with a Disability

    ERIC Educational Resources Information Center

    Pompeo, Michelle N.

    2009-01-01

    This study is a retrospective look at adult female siblings' perspectives of their childhoods and present identities based on having a brother with a disability. This paper focuses on siblings' experiences within educational and public domains, and how such experiences have shaped their personalities and career choices. Qualitative findings were…

  3. "Sometimes I Feel like the Problems Started with Desegregation": Exploring Black Superintendent Perspectives on Desegregation Policy

    ERIC Educational Resources Information Center

    Horsford, Sonya Douglass; McKenzie, Kathryn Bell

    2008-01-01

    This paper is drawn from a larger qualitative study that explores the perspectives of eight retired Black school superintendents who personally experienced segregated schools as students and subsequent desegregation efforts as administrators. Unlike much of the mainstream literature that extols the virtues of desegregation for Black children,…

  4. The Problem of Data in the Cognitive Linguistic Research on Metonymy: A Cross-Linguistic Perspective

    ERIC Educational Resources Information Center

    Brdar-Szabo, Rita; Brdar, Mario

    2012-01-01

    The general goal of the present paper is to demonstrate how cross-linguistic (contrastive) data can broaden the perspective in cognitive linguistic research on metonymy, which may raise a host of questions calling for a revision of some widely accepted views. A more specific, methodological goal is to show how the introspection-driven research and…

  5. Shyness and Social Phobia: A Social Work Perspective on a Problem in Living.

    ERIC Educational Resources Information Center

    Walsh, Joseph

    2002-01-01

    Social phobia can be conceptualized from a social work perspective as an extreme shyness that can be overcome with cognitive learning and behavioral rehearsal. This article reviews the biopsychosocial causes of social phobia and presents a summary of cognitive and behavioral interventions with empirically demonstrated effectiveness. (Author)

  6. Semantic Annotation of Complex Text Structures in Problem Reports

    NASA Technical Reports Server (NTRS)

    Malin, Jane T.; Throop, David R.; Fleming, Land D.

    2011-01-01

    Text analysis is important for effective information retrieval from databases where the critical information is embedded in text fields. Aerospace safety depends on effective retrieval of relevant and related problem reports for the purpose of trend analysis. The complex text syntax in problem descriptions has limited statistical text mining of problem reports. The presentation describes an intelligent tagging approach that applies syntactic and then semantic analysis to overcome this problem. The tags identify types of problems and equipment that are embedded in the text descriptions. The power of these tags is illustrated in a faceted searching and browsing interface for problem report trending that combines automatically generated tags with database code fields and temporal information.

  7. On the Structure of the Fixed Charge Transportation Problem

    ERIC Educational Resources Information Center

    Kowalski, K.

    2005-01-01

    This work extends the theory of the fixed charge transportation problem (FCTP), currently based mostly on a forty-year-old publication by Hirsch and Danzig. This paper presents novel properties that need to be considered by those using existing, or those developing new methods for optimizing FCTP. It also defines the problem in an easier way,…

  8. Perspectives.

    ERIC Educational Resources Information Center

    Robertson, Shari; Camerini, Michael

    2001-01-01

    Provides background information on the U.S. Immigration and Naturalization Service Asylum office. Uses the perspective of two movie producers as they filmed a documentary film, "Well-founded Fear", about asylum and refugee protection. Includes information on how to order a classroom aid and the film. (CMK)

  9. Perspectives

    ERIC Educational Resources Information Center

    Tarone, Elaine

    2013-01-01

    The topic of this "Perspectives" column is "Requiring a Proficiency Level as a Requirement for U.S. K-12 Teacher Licensure." In 1998, the American Council of Teachers of Foreign Languages (ACTFL) began to work with the National Council for Accreditation of Teacher Education (NCATE), which accredits teacher education programs…

  10. Parent and Teacher Perspectives about Problem Behavior in Children with Williams Syndrome

    ERIC Educational Resources Information Center

    Klein-Tasman, Bonita P.; Lira, Ernesto N.; Li-Barber, Kirsten T.; Gallo, Frank J.; Brei, Natalie G.

    2015-01-01

    Problem behavior of 52 children with Williams syndrome ages 6 to 17 years old was examined based on both parent and teacher report. Generally good inter-rater agreement was found. Common areas of problem behavior based both on parent and teacher report included attention problems, anxiety difficulties, repetitive behaviors (e.g., obsessions,…

  11. Middle School Children's Problem-Solving Behavior: A Cognitive Analysis from a Reading Comprehension Perspective

    ERIC Educational Resources Information Center

    Pape, Stephen J.

    2004-01-01

    Many children read mathematics word problems and directly translate them to arithmetic operations. More sophisticated problem solvers transform word problems into object-based or mental models. Subsequent solutions are often qualitatively different because these models differentially support cognitive processing. Based on a conception of problem…

  12. How Can One Learn Mathematical Word Problems in a Second Language? A Cognitive Load Perspective

    ERIC Educational Resources Information Center

    Moussa-Inaty, Jase; Causapin, Mark; Groombridge, Timothy

    2015-01-01

    Language may ordinarily account for difficulties in solving word problems and this is particularly true if mathematical word problems are taught in a language other than one's native language. Research into cognitive load may offer a clear theoretical framework when investigating word problems because memory, specifically working memory, plays a…

  13. Using a Brief Form of Problem-Based Learning in a Research Methods Class: Perspectives of Instructor and Students

    ERIC Educational Resources Information Center

    Elder, Anastasia D.

    2015-01-01

    Problem based learning (PBL) is an instructional method aimed at engaging students in collaboratively solving an ill-structured problem. PBL has been presented and researched as an overhaul of existing curriculum design, yet a modified version may be attractive to college instructors who desire active learning on the part of their students, but…

  14. Elimination of Leprosy as a public health problem by 2000 AD: an epidemiological perspective

    PubMed Central

    Nsagha, Dickson Shey; Bamgboye, Elijah Afolabi; Assob, Jules Clement Nguedia; Njunda, Anna Longdoh; Kamga, Henri Lucien Foumou; Zoung-Kanyi Bissek, Anne-Cécile; Tabah, Earnest Nji; Oyediran, Alain Bankole OO; Njamnshi, Alfred Kongnyu

    2011-01-01

    Introduction Leprosy is caused by Mycobacterium leprae and manifests as damage to the skin and peripheral nerves. The disease is dreaded because it causes deformities, blindness and disfigurement. Worldwide, 2 million people are estimated to be disabled by leprosy. Multidrug therapy is highly effective in curing leprosy, but treating the nerve damage is much more difficult. The World Health Assembly targeted to eliminate leprosy as a public health problem from the world by 2000. The objective of the review was to assess the successes of the leprosy elimination strategy, elimination hurdles and the way forward for leprosy eradication. Methods A structured search was used to identify publications on the elimination strategy. The keywords used were leprosy, elimination and 2000. To identify potential publications, we included papers on leprosy elimination monitoring, special action projects for the elimination of leprosy, modified leprosy elimination campaigns, and the Global Alliance to eliminate leprosy from the following principal data bases: Cochrane data base of systematic reviews, PubMed, Medline, EMBASE, and the Leprosy data base. We also scanned reference lists for important citations. Key leprosy journals including WHO publications were also reviewed. Results The search identified 63 journal publications on leprosy-related terms that included a form of elimination of which 19 comprehensively tackled the keywords including a book on leprosy elimination. In 1991, the 44th World Health Assembly called for the elimination of leprosy as a public health problem in the world by 2000. Elimination was defined as less than one case of leprosy per 10000-population. Elimination has been made possible by a confluence of several orders of opportunities: the scientific (the natural history of leprosy at the present state of knowledge), technological (multi-drug therapy and the blister pack); political (commitment of governments) and financial (support from NGOs for example

  15. Pre-Service Elementary Teachers' Motivation and Ill-Structured Problem Solving in Korea

    ERIC Educational Resources Information Center

    Kim, Min Kyeong; Cho, Mi Kyung

    2016-01-01

    This article examines the use and application of an ill-structured problem to pre-service elementary teachers in Korea in order to find implications of pre-service teacher education with regard to contextualized problem solving by analyzing experiences of ill-structured problem solving. Participants were divided into small groups depending on the…

  16. Mathematical Abstraction in the Solving of Ill-Structured Problems by Elementary School Students in Korea

    ERIC Educational Resources Information Center

    Hong, Jee Yun; Kim, Min Kyeong

    2016-01-01

    Ill-structured problems can be regarded as one of the measures that meet recent social needs emphasizing students' abilities to solve real-life problems. This study aimed to analyze the mathematical abstraction process in solving such problems, and to identify the mathematical abstraction level ([I] Recognition of mathematical structure through…

  17. Solution to certain problems in the failure of composite structures

    NASA Astrophysics Data System (ADS)

    Goodsell, Johnathan

    The present work contains the solution of two problems in composite structures. In the first, an approximate elasticity solution for prediction of the displacement, stress and strain fields within the m-layer, symmetric and balanced angle-ply composite laminate of finite-width subjected anticlastic bending deformation is developed. The solution is shown to recover classical laminated plate theory predictions at interior regions of the laminate and thereby illustrates the boundary layer character of this interlaminar phenomenon. The results exhibit the anticipated response in congruence with the solutions for uniform axial extension and uniform temperature change, where divergence of the interlaminar shearing stress is seen to occur at the intersection of the free-edge and planes between lamina of +theta and -theta orientation. The analytical results show excellent agreement with the finite-element predictions for the same boundary-value problem and thereby provide an efficient and compact solution available for parametric studies of the influence of geometry and material properties. The solution is combined with previously developed solutions for uniform axial extension and uniform temperature change of the identical laminate and the combined solution is exercised to compare the relative magnitudes of free-edge phenomenon arising from the different loading conditions, to study very thick laminates and laminates where the laminate width is less than the laminate thickness. Significantly, it was demonstrated that the solution is valid for arbitrary stacking sequence and the solution was exercised to examine antisymmetric and non-symmetric laminates. Finally, the solution was exercised to determine the dimensions of the boundary layer for very large numbers of layers. It was found that the dimension of the boundary layer width in bending is approximately twice that in uniform axial extension and uniform temperature change. In the second, the intrinsic flaw concept is

  18. The structure of problem behaviours among Irish adolescents.

    PubMed

    Grube, J W; Morgan, M

    1990-05-01

    Problem behaviour theory proposes that adolescent substance use and other problem behaviours comprise a single dimension reflecting a general underlying tendency towards deviance. This general deviance hypothesis was tested with survey data obtained from 2731 adolescents from Dublin, Ireland. A series of hierarchical maximum likelihood factor analyses indicated that three specific factors were necessary to account for the covariation among problem behaviour measures. These factors corresponded to substance use (drinking, smoking, marijuana use, and other drug use), relatively minor problem behaviours (swearing, lying), and relatively serious problem behaviours (stealing, vandalism). Contrary to the general deviance hypothesis, a second order factor representing general deviance accounted for only 14% of the variance in substance use, on the average, as opposed to 74% of the variance in minor and serious problem behaviours. These findings thus indicate that substance use among these Irish adolescents is relatively independent of a general tendency toward deviance. They also suggest that the general deviance hypothesis, as it usually is applied, may be culturally specific and relevant only for adolescents from the United States and similar cultural contexts. PMID:2354284

  19. Integrated Force Method Solution to Indeterminate Structural Mechanics Problems

    NASA Technical Reports Server (NTRS)

    Patnaik, Surya N.; Hopkins, Dale A.; Halford, Gary R.

    2004-01-01

    Strength of materials problems have been classified into determinate and indeterminate problems. Determinate analysis primarily based on the equilibrium concept is well understood. Solutions of indeterminate problems required additional compatibility conditions, and its comprehension was not exclusive. A solution to indeterminate problem is generated by manipulating the equilibrium concept, either by rewriting in the displacement variables or through the cutting and closing gap technique of the redundant force method. Compatibility improvisation has made analysis cumbersome. The authors have researched and understood the compatibility theory. Solutions can be generated with equal emphasis on the equilibrium and compatibility concepts. This technique is called the Integrated Force Method (IFM). Forces are the primary unknowns of IFM. Displacements are back-calculated from forces. IFM equations are manipulated to obtain the Dual Integrated Force Method (IFMD). Displacement is the primary variable of IFMD and force is back-calculated. The subject is introduced through response variables: force, deformation, displacement; and underlying concepts: equilibrium equation, force deformation relation, deformation displacement relation, and compatibility condition. Mechanical load, temperature variation, and support settling are equally emphasized. The basic theory is discussed. A set of examples illustrate the new concepts. IFM and IFMD based finite element methods are introduced for simple problems.

  20. "It's a Difficult Matter": Historical Perspectives on the Enduring Problem of the Practicum in Teacher Preparation

    ERIC Educational Resources Information Center

    Vick, Malcolm

    2006-01-01

    Current reviews of teacher education pay considerable attention to problems associated with the practicum, and often claim to propose major changes in order to improve the quality of new graduates. Many of the problems they address concerning the practicum and its relation to the "theoretical" component of programs are longstanding, and have been…

  1. Critical Thinking in Problem Solving: A Perspective for the Language Arts Teacher.

    ERIC Educational Resources Information Center

    Lundsteen, Sara W.

    Because language arts processes and related skills depend on thinking processes, teachers should know, use, and guide creative problem-solving processes in their language arts class. Creative problem solving involves a balance of divergent and convergent thought, reflected in the processes of creative and critical thinking. Divergent, or creative,…

  2. Developing Physics Concepts through Hands-On Problem Solving: A Perspective on a Technological Project Design

    ERIC Educational Resources Information Center

    Hong, Jon-Chao; Chen, Mei-Yung; Wong, Ashley; Hsu, Tsui-Fang; Peng, Chih-Chi

    2012-01-01

    In a contest featuring hands-on projects, college students were required to design a simple crawling worm using planning, self-monitoring and self-evaluation processes to solve contradictive problems. To enhance the efficiency of problem solving, one needs to practice meta-cognition based on an application of related scientific concepts. The…

  3. Solving the Teacher Shortage Problem in Ghana: Critical Perspectives for Understanding the Issues

    ERIC Educational Resources Information Center

    Cobbold, Cosmas

    2015-01-01

    The problem of getting sufficient numbers of qualified teachers to staff classrooms is one of the most significant public policy issues facing many countries. In Ghana, the problem of teacher shortage has been a perennial one, necessitated by educational expansion as well as adverse socio-economic and political circumstances, and exacerbated by…

  4. Cone-Deciphered Modes of Problem Solving Action (MPSA Cone): Alternative Perspectives on Diversified Professions.

    ERIC Educational Resources Information Center

    Lai, Su-Huei

    A conceptual framework of the modes of problem-solving action has been developed on the basis of a simple relationship cone to assist individuals in diversified professions in inquiry and implementation of theory and practice in their professional development. The conceptual framework is referred to as the Cone-Deciphered Modes of Problem Solving…

  5. Cognitive Load for Configuration Comprehension in Computer-Supported Geometry Problem Solving: An Eye Movement Perspective

    ERIC Educational Resources Information Center

    Lin, John Jr-Hung; Lin, Sunny S. J.

    2014-01-01

    The present study investigated (a) whether the perceived cognitive load was different when geometry problems with various levels of configuration comprehension were solved and (b) whether eye movements in comprehending geometry problems showed sources of cognitive loads. In the first investigation, three characteristics of geometry configurations…

  6. Saudi English-Major Undergraduates' Academic Writing Problems: A Taif University Perspective

    ERIC Educational Resources Information Center

    Al-Khairy, Mohamed Ali

    2013-01-01

    This study attempted to investigate Saudi English-major undergraduates studying at Taif University to identify a) the types of academic writing Saudi English-major undergraduates carry out at English departments, b) Saudi English-major undergraduates' writing problems, c) the reasons behind Saudi English-major undergraduates' writing problems and…

  7. A Developmental Perspective on Peer Rejection, Deviant Peer Affiliation, and Conduct Problems Among Youth.

    PubMed

    Chen, Diane; Drabick, Deborah A G; Burgers, Darcy E

    2015-12-01

    Peer rejection and deviant peer affiliation are linked consistently to the development and maintenance of conduct problems. Two proposed models may account for longitudinal relations among these peer processes and conduct problems: the (a) sequential mediation model, in which peer rejection in childhood and deviant peer affiliation in adolescence mediate the link between early externalizing behaviors and more serious adolescent conduct problems; and (b) parallel process model, in which peer rejection and deviant peer affiliation are considered independent processes that operate simultaneously to increment risk for conduct problems. In this review, we evaluate theoretical models and evidence for associations among conduct problems and (a) peer rejection and (b) deviant peer affiliation. We then consider support for the sequential mediation and parallel process models. Next, we propose an integrated model incorporating both the sequential mediation and parallel process models. Future research directions and implications for prevention and intervention efforts are discussed. PMID:25410430

  8. Statistical properties and network structure of the marriage problem

    NASA Astrophysics Data System (ADS)

    Bouzat, Sebastián; Zanette, Damián H.

    2007-07-01

    We study the statistical properties of the distribution of total energies (or costs) over the set of N! configurations for the marriage problem with N men and N women. Analytical results and exhaustive numerical calculations for the whole configuration space are presented, taking into account several definitions of the individual energies. The distribution of the minimal energy is evaluated approximately. Moreover, we point out a natural association between the configuration space of the marriage problem and a network. We study the topological and metric properties of this network, as well as the distribution of local energy minima on it.

  9. [Problems of formal organizational structure of industrial health care complexes].

    PubMed

    Włodarczyk, C

    1978-01-01

    The author formulates the thesis that the description of organizational structure of industrial health care complex calls for isolation of the following aspects:--structure of territorial links--systemof organizational units and divisions--organization of basic functions--structure of management--structure of supervision of middle and lowe-level personnel--composition of health care complex council--system of accessibility ranges. Each of the above aspects has been considered on the basis of operative rules of law, using organizational analysis methods. PMID:745544

  10. Structuring Video Cases to Support Future Teachers' Problem Solving

    ERIC Educational Resources Information Center

    Kale, Ugur; Whitehouse, Pamela

    2012-01-01

    This study examined preservice teachers' problem-solving skills through the use of an online video case study. Eighty preservice teachers participated in the study with a three-level video presentation by a two-grade-level between-subjects factorial design. The study incorporates a content analysis framework to examine both the components and the…

  11. Typical Behavior of the Linear Programming Method for Combinatorial Optimization Problems: A Statistical-Mechanical Perspective

    NASA Astrophysics Data System (ADS)

    Takabe, Satoshi; Hukushima, Koji

    2014-04-01

    The typical behavior of the linear programming (LP) problem is studied as a relaxation of the minimum vertex cover problem, which is a type of integer programming (IP) problem. To deal with LP and IP using statistical mechanics, a lattice-gas model on the Erdös-Rényi random graphs is analyzed by a replica method. It is found that the LP optimal solution is typically equal to that given by IP below the critical average degree c*=e in the thermodynamic limit. The critical threshold for LP = IP extends the previous result c = 1, and coincides with the replica symmetry-breaking threshold of the IP.

  12. Perspective: Role of structure prediction in materials discovery and design

    NASA Astrophysics Data System (ADS)

    Needs, Richard J.; Pickard, Chris J.

    2016-05-01

    Materials informatics owes much to bioinformatics and the Materials Genome Initiative has been inspired by the Human Genome Project. But there is more to bioinformatics than genomes, and the same is true for materials informatics. Here we describe the rapidly expanding role of searching for structures of materials using first-principles electronic-structure methods. Structure searching has played an important part in unraveling structures of dense hydrogen and in identifying the record-high-temperature superconducting component in hydrogen sulfide at high pressures. We suggest that first-principles structure searching has already demonstrated its ability to determine structures of a wide range of materials and that it will play a central and increasing part in materials discovery and design.

  13. Low NO{sub x} retrofit problems and solutions: A joint perspective

    SciTech Connect

    Penterson, C.A.; Dorman, D.E.

    1995-12-31

    Several utility boilers have been retrofitted with low NO{sub x} burner technology during the past five (5) years in response to the 1990 Clean Air Act Amendments. Though most of the projects have been successful in achieving the primary objective of reducing NO{sub x} emissions, other problems have been created. The most significant problem has been with increased flyash unburned carbon. This paper discusses experiences, problems and some solutions involving three (3) low NO{sub x} retrofit projects implemented by American Electric Power Service Company. These low NO{sub x} retrofit projects involved the following utility boilers: Glen Lyn Unit 6 -- 240 MW front wall fired; Muskingum River Unit 5 -- 600 MW opposed wall cell fired; and Conesville Unit 3 -- 165 MW front wall fired. Performance data will be presented along with solutions to some of the problems encountered.

  14. The Quality of High School Students' Problem Solving from an Expertise Development Perspective

    ERIC Educational Resources Information Center

    Elvira, Quincy; Imants, Jeroen; deMaeyer, Sven; Segers, Mien

    2015-01-01

    The ability to solve problems is a key skill and is essential to our day-to-day lives, at home, at school and at work. The present study explores the quality of managerial problem-solving of participants who are in secondary education. We studied 10th, 11th, and 12th graders following a business track in the Netherlands. Participants were asked to…

  15. A Structure-Agency Perspective on Young Children's Engagement in School Science: Carlos's Performance and Narrative

    ERIC Educational Resources Information Center

    Varelas, Maria; Tucker-Raymond, Eli; Richards, Kimberly

    2015-01-01

    Guided by sociological perspectives that view (young) children as agents who are shaped by and shape the structures of social systems in which they live, we studied forms that agency of young children from historically marginalized groups may take in science class when offered opportunities to engage in science in a variety of ways, how curricular…

  16. Extending the Multiple-Goal Perspective to Tertiary Classroom Goal Structures

    ERIC Educational Resources Information Center

    James, Vennessa H.; Yates, Shirley M.

    2007-01-01

    The multiple-goal perspective has recently been applied to teacher behaviours in primary school classrooms through experimental intervention (Linnenbrink, 2005) and objective observation (Sideridis, 2005). However, there is evidence suggesting that rather than centered only on teacher behaviour, classroom goal structures are a whole class feature…

  17. Cognitive Structures of the Gifted: Theoretical Perspectives, Factor Analysis, Triarchic Theories of Intelligence, and Insight Issues.

    ERIC Educational Resources Information Center

    Shaughnessy, Michael F.

    The paper reviews research on the cognitive structures of gifted students. Theories of R. Sternberg and his triarchic model of intelligence are described. Sternberg asserts that three processes appear to account for insight: selective encoding, selective combination, and selective comparison. H. Gardner's perspective citing six types of…

  18. Nuclear Structure and Decay Data Evaluation: Challenges and Perspectives

    NASA Astrophysics Data System (ADS)

    Kondev, F. G.; Tuli, J. K.

    2003-10-01

    The expression ``Nuclear Structure and Decay Data'' refers to complex nuclear level schemes and tables of numerical values, which quantify fundamental properties of nuclear structure, such as level energies, quantum numbers and state lifetimes, as well as various decay modes and associated radiation. These data are not only at the core of basic nuclear structure and nuclear astrophysics research, but they are also relevant for many applied technologies, including nuclear energy production, reactor design and safety, medical diagnostic and radiotherapy, health physics, environmental research and monitoring, safeguards, material analysis, etc. The mission of the Nuclear Structure and Decay Data Working Group of the US DOE funded Nuclear Data Program is to evaluate, compile, maintain, and disseminate nuclear structure and decay data for all known nuclei (more than 2900!). The network's principal effort is devoted to the timely revision of information in the ENSDF (Evaluated Nuclear Structure Data File) database. However, in recent years, special attention has been given to topical evaluations of properties of particular interest to the nuclear structure community, such as log ft values, α- and proton decay properties, super-deformed and magnetic dipole collective structures, nuclear moments, and nuclear isomers (under development). This presentation will briefly review recent achievements of the network, present on-going activities, and reflect on ideas for future projects and challenges in the field of nuclear structure and decay data evaluation.

  19. Optimal structural design via optimality criteria as a nonsmooth mechanics problem

    NASA Astrophysics Data System (ADS)

    Tzaferopoulos, M. Ap.; Stravroulakis, G. E.

    1995-06-01

    In the theory of plastic structural design via optimality criteria (due to W. Prager), the optimal design problem is transformed to a nonlinear elastic structural analysis problem with appropriate stress-strain laws, which generally include complete vertical branches. In this context, the concept of structural universe (in the sense of G. Rozvany) permits the treatment of complicated optimal layout problems. Recent progress in the field of nonsmooth mechanics makes the solution of structural analysis problems with this kind of 'complete' law possible. Elements from the two fields are combined in this paper for the solution of optimal design and layout problems for structures. The optimal layout of plane trusses with various specific cost functions is studied here as a representative problem. The use of convex, continuous and piecewise linear specific cost functions for the structural members leads to problems of linear variational inequalities or equivalently piecewise linear, convex but nonsmooth optimization problems, which are solved by means of an iterative algorithm based on sequential linear programming techniques. Numerical examples illustrate the theory and its applicability to practical engineering structures. Following a parametric investigation of an optimal bridge design, certain aspects of the optimal truss layout problem are discussed, which can be extended to other types of structural systems as well.

  20. Sampling problems: The small scale structure of precipitation

    NASA Technical Reports Server (NTRS)

    Crane, R. K.

    1981-01-01

    The quantitative measurement of precipitation characteristics for any area on the surface of the Earth is not an easy task. Precipitation is rather variable in both space and time, and the distribution of surface rainfall data given location typically is substantially skewed. There are a number of precipitation process at work in the atmosphere, and few of them are well understood. The formal theory on sampling and estimating precipitation appears considerably deficient. Little systematic attention is given to nonsampling errors that always arise in utilizing any measurement system. Although the precipitation measurement problem is an old one, it continues to be one that is in need of systematic and careful attention. A brief history of the presently competing measurement technologies should aid us in understanding the problem inherent in this measurement task.

  1. The Structure of Metastable States in The Thomson Problem

    NASA Astrophysics Data System (ADS)

    Bondarenko, A. N.; Karchevskiy, M. N.; Kozinkin, L. A.

    2015-11-01

    A practical numerical method for the effective solution of the Thomson Problem is proposed. The developed iterative algorithm allows to conduct theoretical researches such as study of the number of asymptotic solutions depending on the particle count. Metastable states of charged point systems on a unit sphere were considered and the probability of falling into the basin of each state was obtained. Founded upon the algorithm and dual lattice representation approach, the framework for rapid construction of capped carbon nanotubes was created.

  2. Characterising Responsibility in Organisational Structures: The Problem of Many Hands

    NASA Astrophysics Data System (ADS)

    Mastop, Rosja

    Sometimes it is impossible to attribute responsibility to individuals when something goes wrong, or right, especially when many different agents are involved. Moral norms may dictate that certain events are not to happen, but responsibility can only be attributed to an agent if this agent was able to do the right thing, she knew what she ought to do, and she did not accidentally fail in completing her task. The fact that we cannot attribute responsibility for certain unfortunate events due to the absence of these conditions is called the problem of many hands. This contribution presents a logical analysis of the problem of many hands in the framework of XSTIT with intentions, as developed by Jan Broersen. The problem of many hands is analysed in terms of an inference from the existence of a norm and the fact that all agents are acting responsibly to the conclusion that the norm is obeyed. To make that inference valid, additional assumptions are necessary, to ensure that the fairness conditions are met. As the formal analysis shows, tasks can be distributed so as to minimize the gap in this inference, but it cannot be completely bridged: at some point we have to acknowledge that moral responsibility falls short of guaranteeing moral norm fulfilment.

  3. Consensus Problems on Small World Graphs: A Structural Study

    NASA Astrophysics Data System (ADS)

    Hovareshti, Pedram; Baras, John S.

    Consensus problems arise in many instances of collaborative control of multi-agent complex systems; where it is important for the agents to act in coordination with the other agents. To reach coordination, agents need to share information. In large groups of agents the information sharing should be local in some sense, due to energy limitations, reliability, and other constraints. A consensus protocol is an iterative method that provides the group with a common coordination variable. However, local information exchange limits the speed of convergence of such protocols. Therefore, in order to achieve high convergence speed, we should be able to design appropriate network topologies. A reasonable conjecture is that the small world graphs should result in good convergence speed for consensus problems because their low average pairwise path length should speed the diffusion of information in the system. In this paper we address this conjecture by simulations and also by studying the spectral properties of a class of matrices corresponding to consensus problems on small world graphs.

  4. Active Women: Perspectives on Their Structural Position in the Community.

    ERIC Educational Resources Information Center

    Moyer, Harriett; And Others

    An exploratory pilot study to determine the personal characteristics of women community leaders and their position in the power structure was conducted in Chippewa and Eau Claire Counties, Wisconsin. The research design involved a comparison of three samples: the traditional power structure identified through reputational techniques; the active…

  5. Illuminating the dark matter of social neuroscience: Considering the problem of social interaction from philosophical, psychological, and neuroscientific perspectives

    PubMed Central

    Przyrembel, Marisa; Smallwood, Jonathan; Pauen, Michael; Singer, Tania

    2012-01-01

    Successful human social interaction depends on our capacity to understand other people's mental states and to anticipate how they will react to our actions. Despite its importance to the human condition, the exact mechanisms underlying our ability to understand another's actions, feelings, and thoughts are still a matter of conjecture. Here, we consider this problem from philosophical, psychological, and neuroscientific perspectives. In a critical review, we demonstrate that attempts to draw parallels across these complementary disciplines is premature: The second-person perspective does not map directly to Interaction or Simulation theories, online social cognition, or shared neural network accounts underlying action observation or empathy. Nor does the third-person perspective map onto Theory-Theory (TT), offline social cognition, or the neural networks that support Theory of Mind (ToM). Moreover, we argue that important qualities of social interaction emerge through the reciprocal interplay of two independent agents whose unpredictable behavior requires that models of their partner's internal state be continually updated. This analysis draws attention to the need for paradigms in social neuroscience that allow two individuals to interact in a spontaneous and natural manner and to adapt their behavior and cognitions in a response contingent fashion due to the inherent unpredictability in another person's behavior. Even if such paradigms were implemented, it is possible that the specific neural correlates supporting such reciprocal interaction would not reflect computation unique to social interaction but rather the use of basic cognitive and emotional processes combined in a unique manner. Finally, we argue that given the crucial role of social interaction in human evolution, ontogeny, and every-day social life, a more theoretically and methodologically nuanced approach to the study of real social interaction will nevertheless help the field of social cognition

  6. Advances in understanding glycosyltransferases from a structural perspective

    PubMed Central

    Gloster, Tracey M

    2014-01-01

    Glycosyltransferases (GTs), the enzymes that catalyse glycosidic bond formation, create a diverse range of saccharides and glycoconjugates in nature. Understanding GTs at the molecular level, through structural and kinetic studies, is important for gaining insights into their function. In addition, this understanding can help identify those enzymes which are involved in diseases, or that could be engineered to synthesize biologically or medically relevant molecules. This review describes how structural data, obtained in the last 3–4 years, have contributed to our understanding of the mechanisms of action and specificity of GTs. Particular highlights include the structure of a bacterial oligosaccharyltransferase, which provides insights into N-linked glycosylation, the structure of the human O-GlcNAc transferase, and the structure of a bacterial integral membrane protein complex that catalyses the synthesis of cellulose, the most abundant organic molecule in the biosphere. PMID:25240227

  7. Quantum few-body problem with internal structure. I. Two-body problem

    SciTech Connect

    Kuperin, Yu.A.; Makarov, K.A.; Merkur'ev, S.P.; Motovilov, A.K.; Pavlov, B.S.

    1988-12-01

    The methods of the theory of extensions to an auxiliary Hilbert space are used to construct in the two-particle sector a scattering theory for particles possessing internal structure. The analytic properties of the amplitudes of resonance scattering and Green's functions corresponding to a class of singular energy-dependent interactions are investigated.

  8. PREDICTORS OF EMOTIONAL AND BEHAVIORAL PROBLEMS IN 1-YEAR-OLD CHILDREN: A LONGITUDINAL PERSPECTIVE.

    PubMed

    Sirvinskiene, Giedre; Zemaitiene, Nida; Jusiene, Roma; Markuniene, Egle

    2016-07-01

    Emotional and behavioral problems at an early age can reasonably be considered a high-risk factor for later mental health disorders. The aim of the article is to reveal predictive factors of 1½-year-old children's emotional and behavioral problems. The study was a part of a prospective birth-cohort study. The study sample consisted of 172 full-term infants (born during Gestational Weeks 37-42) and their mothers. Emotional and behavioral problems at the age of 1½ years were measured using the Child Behavior Checklist for Ages 1½-5 (T. Achenbach & L. Rescorla, 2000), which was completed by mothers. Emotional and behavioral problems at age of 1½ years were more prevalent in infants born via cesarean section, as compared to infants born vaginally without administration of medication. Newborns' suboptimal functioning after birth, complicated emotional acceptance of pregnancy, a couple's nonsatisfactory relationship during pregnancy, maternal distress during pregnancy and in the first months after childbirth, and inflexible and parent-oriented attitudes toward infant-rearing also predicted children's emotional and behavioral problems independent of sociodemographic factors. Results suggest that biomedical and psychosocial factors which manifest themselves in the prenatal and perinatal periods can have associations with later infant and child mental health. PMID:27336695

  9. Bioinformatics and variability in drug response: a protein structural perspective

    PubMed Central

    Lahti, Jennifer L.; Tang, Grace W.; Capriotti, Emidio; Liu, Tianyun; Altman, Russ B.

    2012-01-01

    Marketed drugs frequently perform worse in clinical practice than in the clinical trials on which their approval is based. Many therapeutic compounds are ineffective for a large subpopulation of patients to whom they are prescribed; worse, a significant fraction of patients experience adverse effects more severe than anticipated. The unacceptable risk–benefit profile for many drugs mandates a paradigm shift towards personalized medicine. However, prior to adoption of patient-specific approaches, it is useful to understand the molecular details underlying variable drug response among diverse patient populations. Over the past decade, progress in structural genomics led to an explosion of available three-dimensional structures of drug target proteins while efforts in pharmacogenetics offered insights into polymorphisms correlated with differential therapeutic outcomes. Together these advances provide the opportunity to examine how altered protein structures arising from genetic differences affect protein–drug interactions and, ultimately, drug response. In this review, we first summarize structural characteristics of protein targets and common mechanisms of drug interactions. Next, we describe the impact of coding mutations on protein structures and drug response. Finally, we highlight tools for analysing protein structures and protein–drug interactions and discuss their application for understanding altered drug responses associated with protein structural variants. PMID:22552919

  10. Cognitive Processes and Knowledge Structures Used in Solving Physics Problems. Final Technical Report.

    ERIC Educational Resources Information Center

    Novak, Gordon S., Jr.

    Cognitive processes and knowledge structures used in physics problem-solving at the high school or freshmen college level were investigated by analysis of expert and novice human problem-solving behavior and by development of computer programs which can solve informally-stated physics problems. Computer representations for the information…

  11. Using Jigsaw-Style Spectroscopy Problem-Solving to Elucidate Molecular Structure through Online Cooperative Learning

    ERIC Educational Resources Information Center

    Winschel, Grace A.; Everett, Renata K.; Coppola, Brian P.; Shultz, Ginger V.

    2015-01-01

    Cooperative learning was employed as an instructional approach to facilitate student development of spectroscopy problem solving skills. An interactive online environment was used as a framework to structure weekly discussions around spectroscopy problems outside of class. Weekly discussions consisted of modified jigsaw-style problem solving…

  12. Analyzing Pre-Service Primary Teachers' Fraction Knowledge Structures through Problem Posing

    ERIC Educational Resources Information Center

    Kilic, Cigdem

    2015-01-01

    In this study it was aimed to determine pre-service primary teachers' knowledge structures of fraction through problem posing activities. A total of 90 pre-service primary teachers participated in this study. A problem posing test consisting of two questions was used and the participants were asked to generate as many as problems based on the…

  13. Structural changes to electronic gaming machines as effective harm minimization strategies for non-problem and problem gamblers.

    PubMed

    Sharpe, Louise; Walker, Michael; Coughlan, Maree-Jo; Enersen, Kirsten; Blaszczynski, Alex

    2005-01-01

    This study aimed to evaluate the effectiveness of three proposed modifications to the structural characteristics of electronic gaming machines as harm minimisation strategies for non-problem and probable problem gamblers. Structural changes included reducing the maximum bet size, reducing reel spin and removing large note acceptors. Behavioural patterns of play were observed in 779 participants attending clubs and hotels. Observations were conducted in the gaming venue during regular gaming sessions. Eight experimental machines were designed to represent every combination of the modifications. 210 participants played at least one modified and one unmodified machine. Following play, the South Oaks Gambling Screen (SOGS) was administered. More problem than non-problem gamblers used high denomination bill acceptors and bet over one-dollar per wager. Machines modified to accept the one-dollar maximum bet were played for less time and were associated with smaller losses, fewer individual wagers and lower levels of alcohol consumption and smoking. It was concluded that the reduction of maximum bet levels was the only modification likely to be effective as a harm minimization strategy for problem gamblers. PMID:16311879

  14. Problems of providing services to people affected by HIV/AIDS: service providers and recipients perspectives.

    PubMed

    Moradi, G; Mohraz, M; Gouya, M M; Dejman, M; Alinaghi, S S; Rahmani, K; Malekafzali-Ardakani, H

    2015-01-01

    This qualitative study aimed to identify the health-care problems of people living with HIV (PLHIV) in 2 large cities: Tehran and Kermanshah. Two main groups of stakeholders - service providers (policy-makers, managers, physicians and counsellors) and service recipients (PLHIV and their relatives) - participated in focus group discussions and in-depth interviews. We identified 24 themes covering the major health problems of PLHIV, including: incomplete and inadequate coverage of health-care services; patients' substance abuse; patients' fear of stigma; occupational burnout of certain service providers; patients' dissatisfaction with some of the services provided by counselling centres/clinics; medical staff's failure to observe confidentiality; and patients' lack of access to required specialized services. The problems and needs identified can inform the design and implementation of health programmes in our country and elsewhere in the Eastern Mediterranean Region. PMID:25907189

  15. Fusion proteins as alternate crystallization paths to difficult structure problems

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Rueker, Florian; Ho, Joseph X.; Lim, Kap; Keeling, Kim; Gilliland, Gary; Ji, Xinhua

    1994-01-01

    The three-dimensional structure of a peptide fusion product with glutathione transferase from Schistosoma japonicum (SjGST) has been solved by crystallographic methods to 2.5 A resolution. Peptides or proteins can be fused to SjGST and expressed in a plasmid for rapid synthesis in Escherichia coli. Fusion proteins created by this commercial method can be purified rapidly by chromatography on immobilized glutathione. The potential utility of using SjGST fusion proteins as alternate paths to the crystallization and structure determination of proteins is demonstrated.

  16. [A historical-epistemological perspective of the ontological problem of Positivism. Positivism and psychiatry].

    PubMed

    Fantin, Juan Carlos

    2005-01-01

    The present article reviews epistemological problems related to the philosophical and scientific current known as Positivism. The revision begins with the study of the historical period during which the Logical Positivism emerges (early in the decade of 1920); and finishes with the analysis of its influence on psychiatry and its relation with other epistemological currents in the same period. The article reviews the historical and epistemological outlook at te beginning of the XX th century, when the problem of language became ontologically outstanding. The question of language remains important in the present discussions. PMID:16314903

  17. Relative Effects of Three Questioning Strategies in Ill-Structured, Small Group Problem Solving

    ERIC Educational Resources Information Center

    Byun, Hyunjung; Lee, Jung; Cerreto, Frank A.

    2014-01-01

    The purpose of this research is to investigate the relative effectiveness of using three different question-prompt strategies on promoting metacognitive skills and performance in ill-structured problem solving by examining the interplay between peer interaction and cognitive scaffolding. An ill-structured problem-solving task was given to three…

  18. Perspectives for the structure-based design of acetylcholinesterase reactivators.

    PubMed

    Ochoa, Rodrigo; Rodriguez, Carlos A; Zuluaga, Andres F

    2016-07-01

    Rational design of active molecules through structure-based methods has been gaining adepts during the last decades due to the wider availability of protein structures, most of them conjugated with relevant ligands. Acetylcholinesterase (AChE) is a molecular target with a considerable amount of data related to its sequence and 3-dimensional structure. In addition, there are structural insights about the mechanism of action of the natural substrate and drugs used in Alzheimer's disease, organophosphorus compounds, among others. We looked for AChE structural data useful for in silico design of potential interacting molecules. In particular, we focused on information regarding the design of ligands aimed to reactivate AChE catalytic activity. The structures of 178 AChE were annotated and categorized on different subsets according to the nature of the ligand, source organisms and experimental details. We compared sequence homology among the active site from Torpedo californica, Mus musculus and Homo sapiens with the latter two species having the closest relationship (88.9% identity). In addition, the mechanism of organophosphorus binding and the design of effective reactivators are reviewed. A curated data collection obtained with information from several sources was included for researchers working on the field. Finally, a molecular dynamics simulation with human AChE indicated that the catalytic pocket volume stabilizes around 600 Å(3), providing additional clues for drug design. PMID:27450771

  19. Adolescent Adjustment in Stepfamilies: Structural or Process Problem?

    ERIC Educational Resources Information Center

    Saint-Jacques, Marie-Christine

    Using Bronfenbrenner's ecological model of human development, this study tested the hypothesis that family processes contribute more to adolescent adjustment than does family structure. Subjects for the study were 234 adolescents between 12 and 16 years old living in a stepfamily on a regular basis. This sample is a sub-sample of a representative…

  20. The Effects of Teaching Programming via Scratch on Problem Solving Skills: A Discussion from Learners' Perspective

    ERIC Educational Resources Information Center

    Kalelioglu, Filiz; Gülbahar, Yasemin

    2014-01-01

    Computer programming is perceived as an important competence for the development of problem solving skills in addition to logical reasoning. Hence, its integration throughout all educational levels, as well as the early ages, is considered valuable and research studies are carried out to explore the phenomenon in more detail. In light of these…

  1. Age and Gender Differences in Coping Style across Various Problems: Omani Adolescents' Perspective

    ERIC Educational Resources Information Center

    Al-Bahrani, Muna; Aldhafri, Said; Alkharusi, Hussain; Kazem, Ali; Alzubiadi, Abdulqawi

    2013-01-01

    This study examines adolescents' coping styles, with relation to their gender and age and level, of six types of problems. The participants were 1843 adolescents (51.7% female and 48.3% male) from the Sultanate of Oman with a mean age of 15.75. Two scales examining general adaptive and maladaptive coping styles and levels of school, economic,…

  2. ESP Teaching at the Institutions of Higher Education in Modern Russia: Problems and Perspectives

    ERIC Educational Resources Information Center

    Prudnikova, Nadezhda

    2013-01-01

    The author analyses ESP teaching at the institutions of higher education in modern Russia, explains the main problems and suggests the ways of their solving, details the quality control system of the students' progress improvement, presents the complex approach to interactive ESP teaching and views it as an integral part of up-to-date…

  3. Children's Comprehension Problems in Oral and Written Language: A Cognitive Perspective. Challenges in Language and Literacy

    ERIC Educational Resources Information Center

    Cain, Kate, Ed.; Oakhill, Jane, Ed.

    2007-01-01

    Comprehension is the ultimate aim of reading and listening. How do children develop the ability to comprehend written and spoken language, and what can be done to help those who are having difficulties? This book presents cutting-edge research on comprehension problems experienced by children without any formal diagnosis as well as those with…

  4. Medical/Behavioral Treatment Perspectives: Case Studies of Mentally Retarded Persons with Maladaptive Behavior Problems.

    ERIC Educational Resources Information Center

    Antonelli, Charles J.

    Five case studies of mentally retarded persons with maladaptive behavior problems are presented to demonstrate an interdisciplinary approach which emphasized coordination between medical and behavioral input in client treatment plans. Case studies involve persons in group home settings who engaged in such maladaptive behaviors as aggression…

  5. Using Problem-Based Case Studies to Learn about Knowledge Translation Interventions: An Inside Perspective

    ERIC Educational Resources Information Center

    Bhogal, Sanjit K.; Murray, Mary Ann; McLeod, Katherine M.; Bergen, Anne; Bath, Brenna; Menon, Anita; Kho, Michelle E.; Stacey, Dawn

    2011-01-01

    Knowledge translation (KT) interventions can facilitate the successful implementation of best practices by engaging and actively involving various stakeholders in the change process. However, for novices, the design of KT interventions can be overwhelming. In this article, we describe our experience as participants in a problem-based case study on…

  6. Cortisol Reactivity, Distress Behavior, and Behavioral and Psychological Problems in Young Adolescents: A Longitudinal Perspective.

    ERIC Educational Resources Information Center

    Susman, Elizabeth J.; And Others

    1997-01-01

    Examined blood cortisol levels, at three 6-month intervals, for young adolescent outpatients in relation to psychological measures derived from patient interviews preceding clinic visits and observed stress behaviors during visits. Found that adolescents in the increased cortisol reactivity group reported more behavior problems and depression…

  7. Students' Perspectives on Problem-Based Learning in a Transitional Doctorate of Physical Therapy Program

    ERIC Educational Resources Information Center

    Larin, Helene M.; Buccieri, Kathleen M.; Wessel, Jean

    2010-01-01

    Doctor of physical therapy (DPT) graduates are expected to be competent in professional behaviors, communication, critical inquiry, clinical decision making, and evidence-based practice. The purpose of this qualitative study was to describe the experience of students enrolled in a single, problem-based learning (PBL) course within a conventional…

  8. A Modeling Perspective on the Teaching and Learning of Mathematical Problem Solving

    ERIC Educational Resources Information Center

    Mousoulides, Nicholas G.; Christou, Constantinos; Sriraman, Bharath

    2008-01-01

    This study analyzed the processes used by students when engaged in modeling activities and examined how students' abilities to solve modeling problems changed over time. Two student populations, one experimental and one control group, participated in the study. To examine students' modeling processes, the experimental group participated in an…

  9. Do Students Trust in Mathematics or Intuition during Physics Problem Solving? An Epistemic Game Perspective

    ERIC Educational Resources Information Center

    Yavuz, Ahmet

    2015-01-01

    This study aims to investigate (1) students' trust in mathematics calculation versus intuition in a physics problem solving and (2) whether this trust is related to achievement in physics in the context of epistemic game theoretical framework. To achieve this research objective, paper-pencil and interview sessions were conducted. A paper-pencil…

  10. Facilitators' Perspectives of the Factors That Affect the Effectiveness of Problem-Based Learning Process

    ERIC Educational Resources Information Center

    Chan, Cecilia K. Y.

    2016-01-01

    Many educational researchers have established problem-based learning (PBL) as a total approach to education--both a product and a process--from a pedagogical instructional strategy to skills development to assessment. This study provides qualitative evidences from educational practitioners in various professional disciplines, namely, Medicine,…

  11. A Perspective on information fusion problems, Extended Abstract, Journal of Distributed Sensor Neworks

    SciTech Connect

    Rao, Nageswara S

    2009-04-01

    Information fusion problems have a rich history spanning four centuries and several disciplines as diverse as political economy, reliability engineering, target tracking, bioinformatics, forecasting, distributed detection, robotics, cyber security, nuclear engineering, distributed sensor networks, and others. Over the past decade, the area of information fusion has been established as a discipline by itself with several contributions to its foundations as well as applications. In a basic formulation of the information fusion problem, each component is characterized by a probability distribution. The goal is to estimate a fusion rule for combining the outputs of components to achieve a specified objective such as better performance or functionality compared to the components. If the sensor error distributions are known, several fusion rule estimation problems have been formulated and solved using deterministic methods. In the area of pattern recognition a weighted majority fuser was shown to be optimal in combining outputs from pattern recognizers under statistical independence conditions. A simpler version of this problem corresponds to the Condorcet Jury theorem proposed in 1786. This result was rediscovered since then in other disciplines including by von Neumann in 1959 in building reliable computing devices. The distributed detection problem, studied extensively in the target tracking area, can be viewed as a generalization of the above two problems. In these works, the underlying distributions are assumed to be known, which is quite reasonable in the areas these methods are applied. In a different formulation, we consider estimating the fuser based on empirical data when no information is available about the underlying distributions of components. Using the empirical estimation methods, this problem is shown to be solvable in principle, and the fuser performance may be sharpened based on the specific formulation. The isolation fusers perform at least as good

  12. Health promotion teams' effectiveness: a structural perspective from Israel.

    PubMed

    Drach-Zahavy, Anat; Baron-Epel, Orna

    2006-09-01

    This study addressed the question of how to structure coalitions in order to increase their engagement in multiple strategies for health promotion and consequently to improve their effectiveness. Three structural variables were chosen: (i) coalition's heterogeneity, captured by the professional diversity of its members; (ii) coalition's configuration, defined as the way members were involved in the coalition: full- or part-cycle membership, full- or part-time assignment, and core or peripheral membership; and (iii) coalition's contractual collaborations with external professionals. A large non-profit network of community centers served as the setting for this study. The sample consisted of 37 coordinators of local coalitions for health promotion in Israel. The study's design was a cross-sectional survey. Data were collected by a multimethod (semistructured interviews, self reported questionnaires and administrative data) approach. Effectiveness was assessed by a self-report questionnaire administrated to coalition coordinators. Engagements in multistrategies as well as structural variables were measured by semistructured interviews with coalition coordinators. Results demonstrated that while a homogeneous, bounded structure seemed to promote the implementation of health education programs, a more flexible coalition configuration with frequent use of professionals contributed more to working by multiple strategies and improved coalition's effectiveness. In addition, the use of external professionals promoted action for a healthier environment, but did not add to empowering the community. The results contribute to shifting the conception of a coalition as a tightly bounded, well-defined, stable entity to that of a more fluid and permeable structure interacting with an external environment. These findings highlight the importance of incorporating structural considerations into the management of coalitions and are discussed in light of the potential costs and benefits

  13. Synthesis, spectroscopic and structural perspective of new ferrocenyl amides

    NASA Astrophysics Data System (ADS)

    Etter, Martin; Nigar, Asifa; Ali, Naveed Zafar; Akhter, Zareen; Dinnebier, Robert E.

    2016-05-01

    Two new ferrocene derivatives with amide linkages were synthesized by the condensation of 4-ferrocenylaniline with n-alkyl acid chloride derivatives as pristine orange solids in good yields. FTIR and 1H/13C NMR studies have confirmed the basic structure of the molecules with the involvement of intermolecular H-bonding, which together with the ferrocene-like packing ensures the stability of the crystal structure. Crystal structures for both compounds were solved by Rietveld refinements of high resolution X-ray powder diffraction data. The XRD results show that both compounds crystallize in the monoclinic space group P21/c. The primary feature of the crystal structure is a double layer of ferrocenyl groups stretched out in the b-c -plane perpendicular to the a-axis, with packing of the ferrocenyl groups occurring in a manner similar to that of pure ferrocene. Despite the close structural similarity, both compounds differ in the optimized geometry of respective Ferrocene conformers. The Cp rings are eclipsed for one Ferrocene conformer and close to staggered for the other, owing to the low energy barrier for the rotation of a cyclopentadienyl ring relative to the rest of the molecule.

  14. [Rehabilitation after kidney transplantation: Old problems and new structures].

    PubMed

    Schiffer, L; Krautzig, S; Gerbig, D; Bintaro, P; Haller, H; Schiffer, M

    2016-01-01

    Kidney transplantation is currently the best therapeutic option for patients with end stage renal disease. Alternative treatment with hemo- or peritoneal dialysis is associated with higher comorbidities, higher morbidity/mortality, and reduced quality of life. Thus, a major aim in posttransplant care is to develop strategies to increase transplant survival and reduce known risk factors and comorbidities. In this overview, we propose a concept to include rehabilitation clinics in all aspects of the transplant process. This concept includes pretransplant care on the waiting list to prepare the patient for the transplant, the direct postoperative treatment phase, and repeated and risk adapted stays in rehabilitation clinics during long-term follow-up to address specific and individual problems. PMID:26684185

  15. Cosmological structure problem of the pre-big bang scenario

    NASA Astrophysics Data System (ADS)

    Hwang, Jai-chan

    1998-02-01

    We calculate the density and gravitational wave spectrums generated in a version of string cosmology termed pre-big bang scenario. The large scale structures are originated from quantum fluctuations of the metric and dilaton field during a pole-like inflation stage driven by a potential-less dilaton field realized in the low-energy effective action of string theory. The generated classical density field and the gravitational wave in the second horizon crossing epoch show tilted spectrums with n ⋍ 4 and n T ⋍ 3 , respectively. These differ from the observed spectrum of the large angular scale anisotropy of the cosmic microwave background radiation which supports scale invariant ones with n ⋍ 1 and n T ⋍ 0 . This suggests that the pre-big bang stage is not suitable for generating the present day observable large scale structures, and suggests the importance of investigating the quantum generation processes during stringy era with higher order quantum correction terms.

  16. NASA Langley's Approach to the Sandia's Structural Dynamics Challenge Problem

    NASA Technical Reports Server (NTRS)

    Horta, Lucas G.; Kenny, Sean P.; Crespo, Luis G.; Elliott, Kenny B.

    2007-01-01

    The objective of this challenge is to develop a data-based probabilistic model of uncertainty to predict the behavior of subsystems (payloads) by themselves and while coupled to a primary (target) system. Although this type of analysis is routinely performed and representative of issues faced in real-world system design and integration, there are still several key technical challenges that must be addressed when analyzing uncertain interconnected systems. For example, one key technical challenge is related to the fact that there is limited data on target configurations. Moreover, it is typical to have multiple data sets from experiments conducted at the subsystem level, but often samples sizes are not sufficient to compute high confidence statistics. In this challenge problem additional constraints are placed as ground rules for the participants. One such rule is that mathematical models of the subsystem are limited to linear approximations of the nonlinear physics of the problem at hand. Also, participants are constrained to use these models and the multiple data sets to make predictions about the target system response under completely different input conditions. Our approach involved initially the screening of several different methods. Three of the ones considered are presented herein. The first one is based on the transformation of the modal data to an orthogonal space where the mean and covariance of the data are matched by the model. The other two approaches worked solutions in physical space where the uncertain parameter set is made of masses, stiffnesses and damping coefficients; one matches confidence intervals of low order moments of the statistics via optimization while the second one uses a Kernel density estimation approach. The paper will touch on all the approaches, lessons learned, validation 1 metrics and their comparison, data quantity restriction, and assumptions/limitations of each approach. Keywords: Probabilistic modeling, model validation

  17. A Structural Perspective on the Regulation of the EGF Receptor

    PubMed Central

    Kovacs, Erika; Zorn, Julie Anne; Huang, Yongjian; Barros, Tiago; Kuriyan, John

    2015-01-01

    The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that plays a critical role in the pathogenesis of many cancers. EGFR is unique in that its ligand-induced dimerization is established solely by contacts between regions of the receptor that are occluded within the monomeric, unliganded state. Activation of EGFR depends on the formation of an asymmetric dimer of the intracellular module of two receptor molecules, a configuration observed in crystal structures of the EGFR kinase domain in the active state. Coupling between the extracellular and intracellular modules is achieved by a switch between alternative geometries of the transmembrane and juxtamembrane segments within the receptor dimer. As the structure of the full-length receptor is yet to be determined, here we review recent structural studies on isolated modules of EGFR and molecular dynamics simulations that have provided much of our current understanding of its signaling mechanism, including how its regulation is compromised by oncogenic mutations. PMID:25621509

  18. Nuclear Structure and Decay Data: Current Status and Future Perspectives

    SciTech Connect

    Kondev, Filip G.; Tuli, Jagdish K.

    2006-03-13

    The nuclear structure databases provide physicists around the world with a useful collection of reliable and well documented datasets. The Evaluated Nuclear Structure Data File (ENSDF) database, produced by the International Nuclear Structure and Decay Data Network (NSDD) under the auspices of the International Atomic Energy Agency (IAEA), contains evaluated experimental information for all known nuclei. The bibliographical database Nuclear Science References (NSR) provides references to published data in the field of Nuclear Physics. The Experimental Unevaluated Nuclear Data List (XUNDL) provides a method for rapid access to formatted (compiled) data from recently published articles. Detailed information regarding these databases, as well as other products and services, can be found at the National Nuclear Data Center (NNDC) and IAEA web portals.

  19. Structural Evolution in Nuclei: The Importance of a Systematic Perspective

    SciTech Connect

    Casten, R.F.

    2005-05-24

    One of the signature features of Raman's work was the love and exploitation of nuclear systematics as a tool to discern interesting structural phenomena and to understand better the evolution of structure with nucleon number. Such a tool, properly used, can be extremely powerful, especially when data are correlated with a physically meaningful variable that yields simple and compact trajectories. It can reveal trends that reflect basic elements of nucleonic interactions, it can reveal nuclei with special symmetries, or anomalous nuclei, and it can point to possibly incorrect measurements. We focus on several uses of correlations of nuclear data, illustrating the above ideas. Particular aspects are proton-neutron interactions, quadrupole collectivity, the search for phase transitional behavior and critical point nuclei, and a new mapping of collective nuclear structure across large parts of the nuclear chart, leading to a discovery of an 'arc of regularity' characterizing certain nuclei while others nearby in Z and N exhibit chaotic spectra.

  20. Perspective: Closing the Dietary Fiber Gap: An Ancient Solution for a 21st Century Problem.

    PubMed

    Thompson, Henry J; Brick, Mark A

    2016-07-01

    An important gap exists between the daily amounts of fiber recommended in the human diet (28-42 g/d) and that which is actually consumed (median intake, 12-14 g/d). In fact, <5% of Americans meet the recommended intake for dietary fiber, and the magnitude of the gap is large, approximately a 50-70% shortfall. Because considerable evidence indicates that dietary fiber affects normal physiologic function and the onset of chronic diseases and their progression, the fiber gap represents an opportune target at which dietary interventions can be directed. This perspective considers whether a scientific basis exists for the current lack of emphasis on pulse crops, that is, grain legumes (common bean, chickpea, lentils, and garden pea) as a concentrated, inexpensive, and widely available source of dietary fiber. Attention is directed to this topic because the fiber gap has existed for decades with little improvement despite nutrition labeling, consumer education about the value of whole-grain cereal crop-based products, and the introduction of many fiber-enriched foods. The time is long overdue to identify additional approaches that have the potential to close the dietary fiber gap. To this end, the potential role of pulse crops in remediating this gap is examined. PMID:27422499

  1. Gauging the Potential of Socially Critical Environmental Education (EE): Examining Local Environmental Problems through Children's Perspective

    ERIC Educational Resources Information Center

    Tsoubaris, Dimitris; Georgopoulos, Aleksandros

    2013-01-01

    The objective of this qualitative research work is to detect the needs, aspirations and feelings of pupils experiencing local environmental problems and elaborate them through the prism of a socially critical educational approach. Semi-structured focus group interviews are used as a research method applied to four primary schools located near…

  2. Strengths and weaknesses of Problem Based Learning from the professional perspective of registered nurses 1

    PubMed Central

    Cónsul-Giribet, María; Medina-Moya, José Luis

    2014-01-01

    OBJECTIVE: to identify competency strengths and weaknesses as perceived by nursing professionals who graduated with a integrated curriculum and competency-based through Problem Based Learning in small groups. METHOD: an intrinsic case study method was used, which analyzes this innovation through former students (from the first class) with three years of professional experience. The data were collected through a questionnaire and discussion groups. RESULTS: the results show that their competency level is valued in a very satisfactory manner. This level paradoxically contrasts with the lack of theoretical knowledge they perceived at the end of their education, when they started working in clinical practice. CONCLUSIONS: the teaching strategy was key to motivate an in-depth study and arouse the desire to know. In addition, Problem Based Learning favors and reinforces the decision to learn, which is that necessary in the course of professional life. PMID:25493666

  3. Human IgG4: a structural perspective

    PubMed Central

    Davies, Anna M; Sutton, Brian J

    2015-01-01

    IgG4, the least represented human IgG subclass in serum, is an intriguing antibody with unique biological properties, such as the ability to undergo Fab-arm exchange and limit immune complex formation. The lack of effector functions, such as antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity, is desirable for therapeutic purposes. IgG4 plays a protective role in allergy by acting as a blocking antibody, and inhibiting mast cell degranulation, but a deleterious role in malignant melanoma, by impeding IgG1-mediated anti-tumor immunity. These findings highlight the importance of understanding the interaction between IgG4 and Fcγ receptors. Despite a wealth of structural information for the IgG1 subclass, including complexes with Fcγ receptors, and structures for intact antibodies, high-resolution crystal structures were not reported for IgG4-Fc until recently. Here, we highlight some of the biological properties of human IgG4, and review the recent crystal structures of IgG4-Fc. We discuss the unexpected conformations adopted by functionally important Cγ2 domain loops, and speculate about potential implications for the interaction between IgG4 and FcγRs. PMID:26497518

  4. The Structure of Women's Employment in Comparative Perspective

    ERIC Educational Resources Information Center

    Pettit, Becky; Hook, Jennifer Lynn

    2005-01-01

    In this paper we analyze social survey data from 19 countries using multi-level modeling methods in an effort to synthesize structural and institutional accounts for variation in women's employment. Observed demographic characteristics show much consistency in their relationship to women's employment across countries, yet there is significant…

  5. Research Articles in Applied Linguistics: Structures from a Functional Perspective

    ERIC Educational Resources Information Center

    Ruiying, Yang; Allison, Desmond

    2004-01-01

    This paper presents the main lines of a genre analysis of the macro-structures of research articles (RAs) in applied linguistics, an area that deserves more attention both for pedagogic and research reasons. The analysis is based upon a detailed study of a corpus of 40 RAs, selected as random sets of 10 drawn from four leading journals in the…

  6. Perspectives of pupils, parents, and teachers on mental health problems among Vietnamese secondary school pupils

    PubMed Central

    2013-01-01

    Background Secondary school can be a stressful period for adolescents, having to cope with many life changes. Very little research has been conducted on the mental health status of secondary school pupils in South East Asian countries, such as Vietnam. The study aimed to explore perceptions of mental health status, risk factors for mental health problems and strategies to improve mental health among Vietnamese secondary school students. Methods A qualitative design was used to address the main study question including: six in-depth interviews conducted with professionals (with two researchers, two psychiatrists, and two secondary school teachers) to learn about their experience of mental health problems among secondary school pupils; 13 focus group discussions (four with teachers, four with parents, and five with pupils); and 10 individual in-depth interviews with pupils who did not take part in the FGDs, to reflect on the collected data and to deepen the authors’ understanding. All interviews and FGDs were audio-taped, transcribed and analyzed for the identification of emerging issues using qualitative techniques of progressive coding, analytic memoing and ongoing comparison. Results Our study confirms the need to pay attention to mental health of pupils in Vietnam. Depression, anxiety, stress, suicidal thoughts and suicide attempts were seen as major problems by all stakeholders. Mental health problems were mainly associated with academic pressure, resulting from an overloaded curriculum and pressure from teachers and parents to succeed. The study found that pupils’ mental health demands interventions at many levels, including at the level of government (Ministry of Education and Training), schools, communities, families and pupils themselves. Conclusions Vietnamese secondary school pupils feel that their mental health status is poor, because of many risk factors in their learning and living environment. The need now is to investigate further to identify and

  7. [Music therapy and "brain music": state of the art, problems and perspectives].

    PubMed

    Fedotchev, A I; Radchenko, G S

    2013-01-01

    Recent literature on the problem of interaction between music and the brain is reviewed and summarized. Mechanisms and effects of two most popular music therapy applications are picked out, including music listening and music making. Special attention is paid to relatively new line of investigations that is called "music of the brain" and deals with transformation of bioelectric processes of human organism into music. Unresolved questions of music therapy are identified and some promising lines of future investigations are delineated. PMID:25438561

  8. [Music therapy and "brain music": state of the art, problems and perspectives].

    PubMed

    2013-01-01

    Recent literature on the problem of interaction between music and the brain is reviewed and summarized. Mechanisms and effects of two most popular music therapy applications are picked out, including music listening and music making. Special attention is paid to relatively new line of investigations that is called "music of the brain" and deals with transformation of bioelectric processes of human organism into music. Unresolved questions of music therapy are identified and some promising lines of future investigations are delineated. PMID:25508092

  9. Cognitive conflict as a teaching strategy in solving chemistry problems: A dialectic-constructivist perspective

    NASA Astrophysics Data System (ADS)

    Niaz, Mansoor

    The main objective of this study was to evaluate the effect of teaching experiments within a dialectic-constructivist framework based on the following considerations: (a) Cognitive conflicts used in the teaching experiments must be based on problem-solving strategies that students find relatively convincing: (b) after having generated a cognitive conflict, it is essential that the students be provided with an experience that could facilitate the resolution of the conflict; and (c) the teaching strategy developed is used by an interactive constructivist approach within an intact classroom. The study was based on two sections of freshman students who had registered for Chemistry I at the Universidad de Oriente, Venezuela. One of the sections was randomly designated as the control group and the other as the experimental group. To introduce cognitive conflict, the experimental group was exposed to two teaching experiments dealing with stoichiometry problems based on the concept of limiting reagent. Students in the control group were exposed to the same problems - however, without the cognitive conflict teaching experiments format. To evaluate the effect of the teaching experiments, both groups were evaluated on five different problems at different intervals during the semester, referred to as posttests. All posttests formed part of the regular evaluation of the students. Results obtained show the advantage of the experimental group on four of the posttests. It is concluded that the experimental treatment was effective in improving performance on the immediate posttests. It was observed that some students protect their core belief [see Lakatos, I. (1970). Falsification and the methodology of scientific research programmes. In I. Lakatos & A. Musgrave (Eds.), Criticism and the growth of knowledge (pp. 91-196). Cambridge: Cambridge University Press] in stoichiometry (establishing equivalent relations between different elements or compounds) by ignoring the conflicting

  10. The Experimental Investigation of the Missing N*- and Δ-RESONANCES Problem:. Current Status and Perspectives

    NASA Astrophysics Data System (ADS)

    Sumachev, V. V.; Bekrenev, V. S.; Beloglazov, Yu. A.; Filimonov, E. A.; Kovalev, A. I.; Kozlenko, N. G.; Kruglov, S. P.; Kulbardis, A. A.; Lopatin, I. V.; Novinsky, D. V.; Shchedrov, V. A.; Trautman, V. Yu.; Alekseev, I. G.; Budkovsky, P. E.; Kanavets, V. P.; Koroleva, L. I.; Morozov, B. V.; Nesterov, V. M.; Ryltsov, V. V.; Sulimov, A. D.; Svirida, D. N.; Bazhanov, N. A.; Bunyatova, E. I.

    2007-11-01

    Numerous attempts to create a model that would exactly reproduce the N* - and Δ - resonances spectrum (that was presented in the Review of Particle Physics) failed. The existing models usually predicted considerably more resonances (twice or more in number) than were found in elastic πN - scattering. This problem is known as the problem of "missing" resonances. The recent partial wave analysis (PWA) SP06 that was made at George Washington University (2006) and included the modern experimental data revealed considerably fewer (approximately half) the N*- and Δ-resonances than those presented in the Review of Particle Physics (RPP) tables (2006). This disagreement invites further experimental investigation of the pion-nucleon interactions. Recent spin rotation parameter A and R measurements of the PNPI and PNPI-ITEP collaborations resolved a part of the twofold ambiguities of the PWA's. These results were used in the last PWA of the George Washington University (GWU) groups. The proposal for the additional measurements of the differential cross section and spin-rotation parameters R and A in the resonance region of the πN interactions is motivated. Such additional experiments are necessary to resolve the problem of the narrow (Γ < 30 MeV) baryon resonances existing and to complete monosemantic PWA of the πN elastic scattering.

  11. A Historical Perspective and Overview of Protein Structure Prediction

    NASA Astrophysics Data System (ADS)

    Wooley, John C.; Ye, Yuzhen

    Carrying on many different biological functions, proteins are all composed of one or more polypeptide chains, each containing from several to hundreds or even thousands of the 20 amino acids. During the 1950s at the dawn of modern biochemistry, an essential question for biochemists was to understand the structure and function of these polypeptide chains. The sequences of protein, also referred to as their primary structures, determine the different chemical properties for different proteins, and thus continue to captivate much of the attention of biochemists. As an early step in characterizing protein chemistry, British biochemist Frederick Sanger designed an experimental method to identify the sequence of insulin (Sanger et al., 1955). He became the first person to obtain the primary structure of a protein and in 1958 won his first Nobel Price in Chemistry. This important progress in sequencing did not answer the question of whether a single (individual) protein has a distinctive shape in three dimensions (3D), and if so, what factors determine its 3D architecture. However, during the period when Sanger was studying the primary structure of proteins, American biochemist Christian Anfinsen observed that the active polypeptide chain of a model protein, bovine pancreatic ribonuclease (RNase), could fold spontaneously into a unique 3D structure, which was later called native conformation of the protein (Anfinsen et al., 1954). Anfinsen also studied the refolding of RNase enzyme and observed that an enzyme unfolded under extreme chemical environment could refold spontaneously back into its native conformation upon changing the environment back to natural conditions (Anfinsen et al., 1961). By 1962, Anfinsen had developed his theory of protein folding (which was summarized in his 1972 Nobel acceptance speech): "The native conformation is determined by the totality of interatomic interactions and hence, by the amino acid sequence, in a given environment."

  12. Structural problems of the Brooks Range ophiolite, Alaska

    SciTech Connect

    Harris, R.A.; Bickerstaff, D. . Dept. of Geology); Stone, D.B. . Geophysical Inst.)

    1993-04-01

    Structural and paleogeographic restorations of the Brooks Range ophiolite (hereafter BRO) and other associated mafic and ultramafic bodies of N. Alaska are difficult because of ambiguous relations between sheeted dikes, cover sediments, and steep NW and SE dipping magmatic flow fabrics. Paleomagnetically enhanced structural studies at Misheguk, Avan, and Siniktanneyak Mountains provide new constraints for the initial dip and sequence of deformation for various structural features of the BRO. The angle between magmatic layers near the petrologic moho and the paleomagnetic inclination of these layers is 50--63[degree] at Misheguk. High level gabbro layers that are disrupted by syn- and post-cooling intrusions display a greater variation. Assuming that the characteristic magnetization is primary, and that the primary inclination was > 80[degree], magmatic layers and the moho had initial dips from 17--40[degree]. These layers now dip 40--70[degree]SE suggesting some post-magmatic tilt. The variation of inclinations with depth in the ophiolite suggest that high level gabbro has tilted most. Sheeted dikes are documented at the Maiyumerak and Siniktanneyak ophiolite bodies. At both locations the dikes dip steeply and strike NE-SW. Sedimentary and volcanic flow layers associated with the dikes have the same strike and dip 0--30[degree]. Parallelism between various planar features throughout the BRO indicates that rotations about a vertical axis are either uniform throughout the ophiolite belt or negligible. Assuming the later, the BRO may represent a linear zone of SSZ magmatism that was oriented NE-SW prior to collision. Post-emplacement long wavelength folding of the ophiolite lid can account for its variation in facing direction and some steepening of magmatic layers.

  13. The cosmic-ray shock structure problem for relativistic shocks

    NASA Technical Reports Server (NTRS)

    Webb, G. M.

    1985-01-01

    The time asymptotic behaviour of a relativistic (parallel) shock wave significantly modified by the diffusive acceleration of cosmic-rays is investigated by means of relativistic hydrodynamical equations for both the cosmic-rays and thermal gas. The form of the shock structure equation and the dispersion relation for both long and short wavelength waves in the system are obtained. The dependence of the shock acceleration efficiency on the upstream fluid spped, long wavelength Mach number and the ratio N = P sub co/cP sub co+P sub go)(Psub co and P sub go are the upstream cosmic-ray and thermal gas pressures respectively) are studied.

  14. The extension problem for partial Boolean structures in quantum mechanics

    NASA Astrophysics Data System (ADS)

    Budroni, Costantino; Morchio, Giovanni

    2010-12-01

    Alternative partial Boolean structures, implicit in the discussion of classical representability of sets of quantum mechanical predictions, are characterized, with definite general conclusions on the equivalence of the approaches going back to Bell and Kochen-Specker. An algebraic approach is presented, allowing for a discussion of partial classical extension, amounting to reduction of the "number of contexts," classical representability arising as a special case. As a result, known techniques are generalized and some of the associated computational difficulties overcome. The implications on the discussion of Boole-Bell inequalities are indicated.

  15. Manipulation of logical structure of chemistry problems and its effect on student performance

    NASA Astrophysics Data System (ADS)

    Niaz, Mansoor; Robinson, William R.

    It has been shown previously that manipulation of the M demand (amount of information needed for processing) of chemistry problems affects student performance, which suggests that manipulation of logical structure of chemistry problems could also lead to significant changes in performance. The objective of this study is to investigate the following: Given the opportunity for training, what is the effect of increasing (manipulation) the complexity of logical structure of chemistry problems on student performance, and to what extent can cognitive variables explain changes in performance. Results obtained show that (a) even a small increase in the logical structure of a problem can change the role of cognitive variables (mental capacity and formal reasoning) to the extent that increase in logical complexity outweighs the advantage students may have gained through training on a similar problem; (b) the use of algorithms and training on particular types of chemistry problems could lead to a situation in which formal reasoning is the only cognitive variable that explains variance in performance significantly; and (c) after having solved very similar problems on two different occasions with improving performance, the improvement is not retained if the logical structure of a third problem increases considerably. It is concluded that when dealing with significant changes in logical complexity of chemistry problems, developmental level of students is the most consistent predictor of success. A model for the qualitative analysis of logical complexity of chemistry problems is presented.

  16. Evolutionary perspectives of telomerase RNA structure and function

    PubMed Central

    Podlevsky, Joshua D.; Chen, Julian J.-L.

    2016-01-01

    ABSTRACT Telomerase is the eukaryotic solution to the ‘end-replication problem’ of linear chromosomes by synthesising the highly repetitive DNA constituent of telomeres, the nucleoprotein cap that protects chromosome termini. Functioning as a ribonucleoprotein (RNP) enzyme, telomerase is minimally composed of the highly conserved catalytic telomerase reverse transcriptase (TERT) and essential telomerase RNA (TR) component. Beyond merely providing the template for telomeric DNA synthesis, TR is an innate telomerase component and directly facilitates enzymatic function. TR accomplishes this by having evolved structural elements for stable assembly with the TERT protein and the regulation of the telomerase catalytic cycle. Despite its prominence and prevalence, TR has profoundly diverged in length, sequence, and biogenesis pathway among distinct evolutionary lineages. This diversity has generated numerous structural and mechanistic solutions for ensuring proper RNP formation and high fidelity telomeric DNA synthesis. Telomerase provides unique insights into RNA and protein coevolution within RNP enzymes. PMID:27359343

  17. Molecular solutes in ionic liquids: a structural perspective.

    PubMed

    Pádua, Agílio A H; Costa Gomes, Margarida F; Canongia Lopes, José N A

    2007-11-01

    Understanding physicochemical properties of ionic liquids is important for their rational use in extractions, reactions, and other applications. Ionic liquids are not simple fluids: their ions are generally asymetric, flexible, with delocalized electrostatic charges, and available in a wide variety. It is difficult to capture their subtle properties with models that are too simplistic. Molecular simulation using atomistic force fields, which describe structures and interactions in detail, is an excellent tool to gain insights into their liquid-state organization, how they solvate different compounds, and what molecular factors determine their properties. The identification of certain ionic liquids as self-organized phases, with aggregated nonpolar and charged domains, provides a new way to interpret the solvation and structure of their mixtures. Many advances are the result of a successful interplay between experiment and modeling, possible in this field where none of the two methodologies had a previous advance. PMID:17661440

  18. Buckling of structures with uncertain imperfections - Personal perspective

    NASA Technical Reports Server (NTRS)

    Elishakoff, Isaac

    1998-01-01

    The previous review on stochastic buckling of structures was written by Amazigo in 1976. This review summarizes some of the developments which took place in recent two decades. A brief overview is given of the effect on uncertainty in the initial geometric imperfections, elastic moduli, applied forces, and thickness variation. For the benefit of the thinking reader, the review has a critical nature. It should be noted that this manuscript has yet to be completed.

  19. A global perspective on marine photosynthetic picoeukaryote community structure

    PubMed Central

    Kirkham, Amy R; Lepère, Cécile; Jardillier, Ludwig E; Not, Fabrice; Bouman, Heather; Mead, Andrew; Scanlan, David J

    2013-01-01

    A central goal in ecology is to understand the factors affecting the temporal dynamics and spatial distribution of microorganisms and the underlying processes causing differences in community structure and composition. However, little is known in this respect for photosynthetic picoeukaryotes (PPEs), algae that are now recognised as major players in marine CO2 fixation. Here, we analysed dot blot hybridisation and cloning–sequencing data, using the plastid-encoded 16S rRNA gene, from seven research cruises that encompassed all four ocean biomes. We provide insights into global abundance, α- and β-diversity distribution and the environmental factors shaping PPE community structure and composition. At the class level, the most commonly encountered PPEs were Prymnesiophyceae and Chrysophyceae. These taxa displayed complementary distribution patterns, with peak abundances of Prymnesiophyceae and Chrysophyceae in waters of high (25:1) or low (12:1) nitrogen:phosphorus (N:P) ratio, respectively. Significant differences in phylogenetic composition of PPEs were demonstrated for higher taxonomic levels between ocean basins, using Unifrac analyses of clone library sequence data. Differences in composition were generally greater between basins (interbasins) than within a basin (intrabasin). These differences were primarily linked to taxonomic variation in the composition of Prymnesiophyceae and Prasinophyceae whereas Chrysophyceae were phylogenetically similar in all libraries. These data provide better knowledge of PPE community structure across the world ocean and are crucial in assessing their evolution and contribution to CO2 fixation, especially in the context of global climate change. PMID:23364354

  20. The Influence of Gender and Sexual Orientation on Alcohol Use and Alcohol-Related Problems: Toward a Global Perspective.

    PubMed

    Hughes, Tonda L; Wilsnack, Sharon C; Kantor, Lori Wolfgang

    2016-01-01

    Although there are wide differences in alcohol use patterns among countries, men are consistently more likely than women to be drinkers and to drink heavily. Studies of alcohol use among sexual minorities (SMs), however, reflect a more complex picture. Such research has found higher rates of alcohol use and alcohol-related problems among SM persons than among heterosexuals and greater differences between SM and heterosexual women than between SM and heterosexual men. A variety of factors may contribute to differences in alcohol use and alcohol-related problems between men and women and between SM and heterosexual people. An improved understanding of these factors is important to guide prevention and treatment efforts. Although there is a dearth of literature on use of alcohol by SMs in many parts of the world, especially lower- and middle-income countries, we attempt to review and integrate the sparse data that are available from these lower-resourced countries. The global perspective presented in this article is the first attempt to go beyond a general review of literature in the Western world to document the gender paradox in alcohol use among heterosexuals and SMs in diverse countries worldwide. PMID:27159819

  1. Raman-based geobarometry of ultrahigh-pressure metamorphic rocks: applications, problems, and perspectives.

    PubMed

    Korsakov, Andrey V; Zhukov, Vladimir P; Vandenabeele, Peter

    2010-08-01

    Raman-based geobarometry has recently become increasingly popular because it is an elegant way to obtain information on peak metamorphic conditions or the entire pressure-temperature-time (P-T-t) path of metamorphic rocks, especially those formed under ultrahigh-pressure (UHP) conditions. However, several problems need to be solved to get reliable estimates of metamorphic conditions. In this paper we present some examples of difficulties which can arise during the Raman spectroscopy study of solid inclusions from ultrahigh-pressure metamorphic rocks. PMID:20582407

  2. Pilins in gram-positive bacteria: A structural perspective.

    PubMed

    Krishnan, Vengadesan

    2015-07-01

    Pilins or fimbrilins are a class of proteins found in bacterial surface pilus, a hair-like surface appendage. Both the Gram-negative and -positive bacteria produce pilins to assemble pili on their cell-surface for different purposes including adherence, twitching motility, conjugation, immunomodulation, biofilm formation, and electron transfer. Immunogenic properties of the pilins make them attractive vaccine candidates. The polymerized pilins play a key role in the initiation of host adhesion, which is a critical step for bacterial colonization and infection. Because of their key role in adhesion and exposure on the cell surface, targeting the pilins-mediated adhesion (anti-adhesion therapy) is also seen as a promising alternative approach for preventing and treating bacterial infections, one that may overcome their ever-increasing repertoires of resistance mechanisms. Individual pilins interact with each other non-covalently to assemble the pilus fiber with the help of associated proteins like chaperones and Usher in Gram-negative bacteria. In contrast, the pilins in Gram-positive bacteria often connect with each other covalently, with the help of sortases. Certain unique structural features present on the pilins distinguish them from one another across different bacterial strains, and these dictate their cellular targets and functions. While the structure of pilins has been extensively studied in Gram-negative pathogenic bacteria, the pilins in Gram-positive pathogenic bacteria have been in only during the last decade. Recently, the discovery of pilins in non-pathogenic bacteria, such as Lactobacillus rhamnosus GG, has received great attention, though traditionally the attention was on pathogenic bacteria. This review summarizes and discusses the current structural knowledge of pilins in Gram-positive bacteria with emphasis on those pilins which are sortase substrates. PMID:26178080

  3. Near Earth Objects and Cascading Effects from the Policy Perspective: Implications from Problem and Solution Definition

    NASA Astrophysics Data System (ADS)

    Lindquist, Eric

    2016-04-01

    The characterization of near-Earth-objects (NEOs) in regard to physical attributes and potential risk and impact factors presents a complex and complicates scientific and engineering challenge. The societal and policy risks and impacts are no less complex, yet are rarely considered in the same context as material properties or related factors. Further, NEO impacts are typically considered as discrete events, not as initial events in a dynamic cascading system. The objective of this contribution is to position the characterization of NEOs within the public policy process domain as a means to reflect on the science-policy nexus in regard to risks and multi-hazard impacts associated with these hazards. This will be accomplished through, first, a brief overview of the science-policy nexus, followed by a discussion of policy process frameworks, such as agenda setting and the multiple streams model, focusing events, and punctuated equilibrium, and their application and appropriateness to the problem of NEOs. How, too, for example, does NEO hazard and risk compare with other low probability, high risk, hazards in regard to public policy? Finally, we will reflect on the implications of alternative NEO "solutions" and the characterization of the NEO "problem," and the political and public acceptance of policy alternatives as a way to link NEO science and policy in the context of the overall NH9.12 panel.

  4. The Dreyfus model of clinical problem-solving skills acquisition: a critical perspective

    PubMed Central

    Peña, Adolfo

    2010-01-01

    Context The Dreyfus model describes how individuals progress through various levels in their acquisition of skills and subsumes ideas with regard to how individuals learn. Such a model is being accepted almost without debate from physicians to explain the ‘acquisition’ of clinical skills. Objectives This paper reviews such a model, discusses several controversial points, clarifies what kind of knowledge the model is about, and examines its coherence in terms of problem-solving skills. Dreyfus' main idea that intuition is a major aspect of expertise is also discussed in some detail. Relevant scientific evidence from cognitive science, psychology, and neuroscience is reviewed to accomplish these aims. Conclusions Although the Dreyfus model may partially explain the ‘acquisition’ of some skills, it is debatable if it can explain the acquisition of clinical skills. The complex nature of clinical problem-solving skills and the rich interplay between the implicit and explicit forms of knowledge must be taken into consideration when we want to explain ‘acquisition’ of clinical skills. The idea that experts work from intuition, not from reason, should be evaluated carefully. PMID:20563279

  5. Characterization of NEOs from the Policy Perspective: Implications from Problem and Solution Definitions

    NASA Astrophysics Data System (ADS)

    Lindquist, E.

    2015-12-01

    The characterization of near-Earth-objects (NEOs) in regard to physical attributes and potential risk and impact factors presents a complex and complicates scientific and engineering challenge. The societal and policy risks and impacts are no less complex, yet are rarely considered in the same context as material properties or related factors. The objective of this contribution is to position the characterization of NEOs within the public policy process domain as a means to reflect on the science-policy nexus in regard to risks associated with NEOs. This will be accomplished through, first, a brief overview of the science-policy nexus, followed by a discussion of several policy process frameworks, such as agenda setting and the multiple streams model, focusing events, and punctuated equilibrium, and their application and appropriateness to the problem of NEOs. How, too, for example, does NEO hazard and risk compare with other low probability, high risk, hazards in regard to public policy? Finally, we will reflect on the implications of alternative NEO "solutions" and the characterization of the NEO "problem," and the political and public acceptance of policy alternatives as a way to link NEO science and policy in the context of the overall NH004 panel.

  6. A Perspective on the Differences between Expert and Novice Performance in Solving Physics Problems.

    ERIC Educational Resources Information Center

    Champagne, Audrey B.; And Others

    The research described in this paper leads to an instructional design approach which is an alternative to the consideration of such issues as mathematical skills or level of cognitive development. The approach uses an analysis of traditional instructional tasks to specify the underlying cognitive processes and structures necessary for the…

  7. The effect of neighborhood structures on tabu search algorithm in solving university course timetabling problem

    NASA Astrophysics Data System (ADS)

    Shakir, Ali; AL-Khateeb, Belal; Shaker, Khalid; Jalab, Hamid A.

    2014-12-01

    The design of course timetables for academic institutions is a very difficult job due to the huge number of possible feasible timetables with respect to the problem size. This process contains lots of constraints that must be taken into account and a large search space to be explored, even if the size of the problem input is not significantly large. Different heuristic approaches have been proposed in the literature in order to solve this kind of problem. One of the efficient solution methods for this problem is tabu search. Different neighborhood structures based on different types of move have been defined in studies using tabu search. In this paper, different neighborhood structures on the operation of tabu search are examined. The performance of different neighborhood structures is tested over eleven benchmark datasets. The obtained results of every neighborhood structures are compared with each other. Results obtained showed the disparity between each neighborhood structures and another in terms of penalty cost.

  8. Comments on the three papers by the FDA/CDER research team on the regulatory perspective of the missing data problem.

    PubMed

    Shih, Weichung Joe

    2016-07-30

    This communication comments on the three papers by the FDA CDER research team on the regulatory perspective of the missing data problem. The focus is on two topics: causal estimand and sensitivity analysis. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27374355

  9. Clinician and Parent Perspectives on Parent and Family Contextual Factors that Impact Community Mental Health Services for Children with Behavior Problems

    ERIC Educational Resources Information Center

    Baker-Ericzen, Mary J.; Jenkins, Melissa M.; Brookman-Frazee, Lauren

    2010-01-01

    The present study employed qualitative methods to examine multiple stakeholder perspectives regarding the role of parent and family contextual factors on community child mental health treatment for children with behavior problems. Findings suggest agreement between clinicians and parents on the number, types and importance of parent and family…

  10. The Use of Video Cases in a Multimedia Learning Environment for Facilitating High School Students' Inquiry into a Problem from Varying Perspectives

    ERIC Educational Resources Information Center

    Zydney, Janet Mannheimer; Grincewicz, Amy

    2011-01-01

    This study investigated the connection between the use of video cases within a multimedia learning environment and students' inquiry into a socio-scientific problem. The software program was designed based on principles from the Cognitive Flexibility Theory (CFT) and incorporated video cases of experts with differing perspectives. Seventy-nine…

  11. Gelatin yarns inspired by tendons--structural and mechanical perspectives.

    PubMed

    Selle, Hila Klein; Bar-On, Benny; Marom, Gad; Wagner, H Daniel

    2015-02-01

    Tendons are among the most robust structures in nature. Using the structural properties of natural tendon as a foundation for the development of micro-yarns may lead to innovative composite materials. Gelatin monofilaments were prepared by casting and spinning and small yarns--with up to ten filaments--were assembled into either parallel or 15° twisted yarns. The latter were intended as an attempt to generate mechanical effects similar to those arising from the crimp pattern in tendon. The mechanical properties of parallel and 15° twisted gelatin yarns were compared. The effect of an increasing number of filaments per yarn was also examined. The mechanical properties were mostly affected by the increasing number of filaments, and no benefit arose from twisting small yarns by 15°. However, since gelatin filaments are elasto-plastic rather than fully elastic, much increased toughness (by up to a factor of five for a ten filament yarn) can be achieved with yarns made of elasto-plastic filaments, as demonstrated by experiments and numerical simulations. The resulting effect shows some resemblance to the effect of crimp in tendons. Finally, we developed a dependable procedure to measure the toughness of single filaments based on the test of a yarn rather than on a large number of individual filament tests. PMID:25492166

  12. Structure-property relationships of multiferroic materials: A nano perspective

    NASA Astrophysics Data System (ADS)

    Bai, Feiming

    The integration of sensors, actuators, and control systems is an ongoing process in a wide range of applications covering automotive, medical, military, and consumer electronic markets. Four major families of ceramic and metallic actuators are under development: piezoelectrics, electrostrictors, magnetostrictors, and shape-memory alloys. All of these materials undergo at least two phase transformations with coupled thermodynamic order parameters. These transformations lead to complex domain wall behaviors, which are driven by electric fields (ferroelectrics), magnetic fields (ferromagnetics), or mechanical stress (ferroelastics) as they transform from nonferroic to ferroic states, contributing to the sensing and actuating capabilities. This research focuses on two multiferroic crystals, Pb(Mg1/3Nb 2/3)O3-PbTiO3 and Fe-Ga, which are characterized by the co-existence and coupling of ferroelectric polarization and ferroelastic strain, or ferro-magnetization and ferroelastic strain. These materials break the conventional boundary between piezoelectric and electrostrictors, or magnetostrictors and shape-memory alloys. Upon applying field or in a poled condition, they yield not only a large strain but also a large strain over field ratio, which is desired and much benefits for advanced actuator and sensor applications. In this thesis, particular attention has been given to understand the structure-property relationships of these two types of materials from atomic to the nano/macro scale. X-ray and neutron diffraction were used to obtain the lattice structure and phase transformation characteristics. Piezoresponse and magnetic force microscopy were performed to establish the dependence of domain configurations on composition, thermal history and applied fields. It has been found that polar nano regions (PNRs) make significant contributions to the enhanced electromechanical properties of PMN-x%PT crystals via assisting intermediate phase transformation. With increasing PT

  13. A Conceptual Framework Mapping the Application of Information Search Strategies to Well and Ill-Structured Problem Solving

    ERIC Educational Resources Information Center

    Laxman, Kumar

    2010-01-01

    Problem-based learning (PBL) is an instructional approach that is organized around the investigation and resolution of problems. Problems are neither uniform nor similar. Jonassen (1997, 2000) in his design theory of problem solving has categorized problems into two broad types--well-structured and ill-structured. He has also described a host of…

  14. Palaeo sea-level and ice-sheet databases: problems, strategies and perspectives

    NASA Astrophysics Data System (ADS)

    Düsterhus, A.; Rovere, A.; Carlson, A. E.; Barlow, N. L. M.; Bradwell, T.; Dutton, A.; Gehrels, R.; Hibbert, F. D.; Hijma, M. P.; Horton, B. P.; Klemann, V.; Kopp, R. E.; Sivan, D.; Tarasov, L.; Törnqvist, T. E.

    2015-06-01

    Sea-level and ice-sheet databases are essential tools for evaluating palaeoclimatic changes. However, database creation poses considerable challenges and problems related to the composition and needs of scientific communities creating raw data, the compiliation of the database, and finally using it. There are also issues with data standardisation and database infrastructure, which should make the database easy to understand and use with different layers of complexity. Other challenges are correctly assigning credit to original authors, and creation of databases that are centralised and maintained in long-term digital archives. Here, we build on the experience of the PALeo constraints on SEA level rise (PALSEA) community by outlining strategies for designing a self-consistent and standardised database of changes in sea level and ice sheets, identifying key points that need attention when undertaking the task of database creation.

  15. A theoretical perspective on particle acceleration by interplanetary shocks and the Solar Energetic Particle problem

    NASA Astrophysics Data System (ADS)

    Verkhoglyadova, Olga P.; Zank, Gary P.; Li, Gang

    2015-02-01

    Understanding the physics of Solar Energetic Particle (SEP) events is of importance to the general question of particle energization throughout the cosmos as well as playing a role in the technologically critical impact of space weather on society. The largest, and often most damaging, events are the so-called gradual SEP events, generally associated with shock waves driven by coronal mass ejections (CMEs). We review the current state of knowledge about particle acceleration at evolving interplanetary shocks with application to SEP events that occur in the inner heliosphere. Starting with a brief outline of recent theoretical progress in the field, we focus on current observational evidence that challenges conventional models of SEP events, including complex particle energy spectra, the blurring of the distinction between gradual and impulsive events, and the difference inherent in particle acceleration at quasi-parallel and quasi-perpendicular shocks. We also review the important problem of the seed particle population and its injection into particle acceleration at a shock. We begin by discussing the properties and characteristics of non-relativistic interplanetary shocks, from their formation close to the Sun to subsequent evolution through the inner heliosphere. The association of gradual SEP events with shocks is discussed. Several approaches to the energization of particles have been proposed, including shock drift acceleration, diffusive shock acceleration (DSA), acceleration by large-scale compression regions, acceleration by random velocity fluctuations (sometimes known as the "pump mechanism"), and others. We review these various mechanisms briefly and focus on the DSA mechanism. Much of our emphasis will be on our current understanding of the parallel and perpendicular diffusion coefficients for energetic particles and models of plasma turbulence in the vicinity of the shock. Because of its importance both to the DSA mechanism itself and to the particle

  16. Materials by Design-A Perspective From Atoms to Structures.

    PubMed

    Buehler, Markus J

    2013-02-01

    Biological materials are effectively synthesized, controlled, and used for a variety of purposes-in spite of limitations in energy, quality, and quantity of their building blocks. Whereas the chemical composition of materials in the living world plays a some role in achieving functional properties, the way components are connected at different length scales defines what material properties can be achieved, how they can be altered to meet functional requirements, and how they fail in disease states and other extreme conditions. Recent work has demonstrated this by using large-scale computer simulations to predict materials properties from fundamental molecular principles, combined with experimental work and new mathematical techniques to categorize complex structure-property relationships into a systematic framework. Enabled by such categorization, we discuss opportunities based on the exploitation of concepts from distinct hierarchical systems that share common principles in how function is created, linking music to materials science. PMID:24163499

  17. Twin Masks of Spiral Structure? A Local Perspective

    NASA Astrophysics Data System (ADS)

    Steiman-Cameron, Thomas Y.

    We examine models for the spiral structure of the Milky Way proposed over the past half century. Many approaches have been pursued to decipher the geometry of the Galaxy's spiral arms, often with conflicting results. While a general consensus exists that a global pattern exists, considerable disagreement remains in the details. Arm geometries, orientations, and even the number of arms are still debated. Close examination of the literature reveals a clear division between four- and two-arm spiral arms. Four-arm models follow naturally from observations of classical tracers of spiral arms - enhanced gas densities and associated star formation - while two-arm models primarily flow from observations linked to the distribution of cool evolved stars. We examine the dichotomy between two-arm and four-arm models and discuss its implications.

  18. Structural and Electronic Properties of Isolated Nanodiamonds: A Theoretical Perspective

    SciTech Connect

    Raty, J; Galli, G

    2004-09-09

    Nanometer sized diamond has been found in meteorites, proto-planetary nebulae and interstellar dusts, as well as in residues of detonation and in diamond films. Remarkably, the size distribution of diamond nanoparticles appears to be peaked around 2-5 nm, and to be largely independent of preparation conditions. Using ab-initio calculations, we have shown that in this size range nanodiamond has a fullerene-like surface and, unlike silicon and germanium, exhibit very weak quantum confinement effects. We called these carbon nanoparticles bucky-diamonds: their atomic structure, predicted by simulations, is consistent with many experimental findings. In addition, we carried out calculations of the stability of nanodiamond which provided a unifying explanation of its size distribution in extra-terrestrial samples, and in ultra-crystalline diamond films. Here we present a summary of our theoretical results and we briefly outline work in progress on doping of nanodiamond with nitrogen.

  19. 8-Hydroxyquinolines in medicinal chemistry: A structural perspective.

    PubMed

    Oliveri, Valentina; Vecchio, Graziella

    2016-09-14

    8-Hydroxyquinolines are heterocyclic compounds characterized by a moderate metal-binding affinity. The interest in 8-hydroxyquinolines has grown exponentially in the last two decades as they are privileged structures for the design of new drug candidates that exert a host of biological effects on various targets. The study of biological activities such as neuroprotection, anticancer, antibacterial, antifungal activity has been further promoted by the synthetic versatility of 8-hydroxyquinoline, which allows the generation of a large number of derivatives. These include numerous multifunctional analogues having the metal-binding motif of 8-hydroxyquinoline. In this review, we have summarized 8-hydroxyquinolines, 8-hydroxyquinoline-like compounds, 8-hydroxyquinoline-loaded nanoparticle systems with respect to their biological activities, interaction with metal ions and mechanisms of action. PMID:27191619

  20. Structure, function and evolution of the gas exchangers: comparative perspectives

    PubMed Central

    Maina, JN

    2002-01-01

    Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that ‘necessity is the mother of invention’, gas exchangers have been inaugurated through stiff cost–benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural–functional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones ofthe modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices – water or air – within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animalshave adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water–air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed. PMID:12430953

  1. Some New Problems on Shells and Thin Structures

    NASA Technical Reports Server (NTRS)

    Vlasov, V. S.

    1949-01-01

    Cylindrical shells of arbitrary section, reinforced by longitudinal and transverse members (stringers and ribs) are considered by us, for a sufficiently close spacing of the ribs, as in our previously published papers (references 1 end 2), as thin-walled orthotropic spatial systems at the cross-sections of which only axial (normal and shearing) forces can arise. The longitudinal bending and twisting moments, due to their weak effect on the stress state of the shell, are taken equal to zero. Along the longitudinal sections of the shell there may arise transverse forces in addition to the normal d shearing forces. Under the so-called static assumptions there is taken for the computation model of the shell a thin-walled spatial system consisting along its length (along a generator) of an infinite number of elementary strips capable of bending. Each of these strips is likened to a curved rod operating in each of its sections not only in tension (compression)but also in transverse bending and shear. The interaction between two adjoining transverse strips in the shell expresses itself in the transmission from one strip to the other of only the normal and shearing stresses. The static structure of the computation model here described is shown in figure 1, where the connections through which the normal and shearing stresses transmitted from one transverse strip to smother are indicated schematically by the rods located in the middle surface of the shell. In addition to the static hypothesis we introduce also geometric hypotheses. According to the latter the elongational deformations of the shell along lines parallel to the generator of its middle surface and the shear deformations in the middle surface, as ma+gitudes having . little effect on the state of the fundamental internal forces of the shell, are taken equal to zero. The deformations of the shell in our computational model are such that in the first place the lines of this surface perpendicular to the generator are

  2. Structure-approximating inverse protein folding problem in the 2D HP model.

    PubMed

    Gupta, Arvind; Manuch, Ján; Stacho, Ladislav

    2005-12-01

    The inverse protein folding problem is that of designing an amino acid sequence which has a particular native protein fold. This problem arises in drug design where a particular structure is necessary to ensure proper protein-protein interactions. In this paper, we show that in the 2D HP model of Dill it is possible to solve this problem for a broad class of structures. These structures can be used to closely approximate any given structure. One of the most important properties of a good protein (in drug design) is its stability--the aptitude not to fold simultaneously into other structures. We show that for a number of basic structures, our sequences have a unique fold. PMID:16379538

  3. Structural vulnerability and problem drinking among Latino migrant day laborers in the San Francisco Bay Area.

    PubMed

    Worby, Paula A; Organista, Kurt C; Kral, Alex H; Quesada, James; Arreola, Sonya; Khoury, Sahar

    2014-08-01

    Latino migrant day laborers (LMDLs) live under challenging conditions in the San Francisco Bay Area. This study explored day laborer alcohol use guided by a structural vulnerability framework, specifically problem vs. non-problem drinking as perceived by LMDLs and how they cope with or try to avoid problem drinking given their broader environment. The study utilized ethnographic methods including in-depth semi-structured qualitative interviews with 51 LMDLs. Findings revealed the considerable challenge of avoiding problem drinking given socio-environmental factors that influence drinking: impoverished living and working conditions, prolonged separation from home and family, lack of work authorization, consequent distress and negative mood states, and peer pressure to drink. While participants shared strategies to avoid problem drinking, the success of individual-level efforts is limited given the harsh structural environmental factors that define day laborers' daily lives. Discussed are implications for prevention and intervention strategies at the individual, community, national and international levels. PMID:25130240

  4. The cosmological {sup 7}Li problem from a nuclear physics perspective

    SciTech Connect

    Broggini, C.; Canton, L.; Fiorentini, G.; Villante, F.L. E-mail: luciano.canton@pd.infn.it E-mail: francesco.villante@lngs.infn.it

    2012-06-01

    The primordial abundance of {sup 7}Li as predicted by Big Bang Nucleosynthesis (BBN) is more than a factor 2 larger than what has been observed in metal-poor halo stars. Herein, we analyze the possibility that this discrepancy originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. To do this, we introduce an efficient method to calculate the changes in the {sup 7}Li abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. Then, considering that {sup 7}Li is mainly produced from {sup 7}Be via the electron capture process {sup 7}Be+e{sup −} → {sup 7}Li+ν{sub e}, we assess the impact of the various channels of {sup 7}Be destruction. Differently from previous analysis, we consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration and that does not rely on the use of the narrow-resonance approximation. As a result of this, the possibility of a nuclear physics solution to the {sup 7}Li problem is significantly suppressed. Given the present experimental and theoretical constraints, it is unlikely that the {sup 7}Be+n destruction rate is underestimated by the 2.5 factor required to solve the problem. We exclude, moreover, that resonant destruction in the channels {sup 7}Be+t and {sup 7}Be+{sup 3}He can explain the {sup 7}Li puzzle. New unknown resonances in {sup 7}Be+d and {sup 7}Be+α could potentially produce significant effects. Recent experimental results have ruled out such a possibility for {sup 7}Be+d. On the other hand, for the {sup 7}Be+α channel very favorable conditions are required. The possible existence of a partially suitable resonant level in {sup 11}C is studied in the framework of a coupled-channel model and the possibility of a direct measurement is considered.

  5. Metals for Cryotank Structures. Present and Future: MSFC Perspective

    NASA Technical Reports Server (NTRS)

    Vaughn, Timothy P.

    1999-01-01

    The Cryogenic Tank Technology Program (CTTP) program has been a cooperative effort between NASA LARC, NASA MSFC, NASA Headquarters, and industry (Lockheed Martin Aeronautics, Lockheed Martin Manned Space Systems, Wyman Gordon, and Ladish). The scope of the CTTP is to develop state-of-the-art, flight-size, flight-quality, low cost hardware, and use this hardware to design, fabricate and test an all aluminum-lithium, all near net shape-component 14' diameter cryogenic tank with a unique low profile bulkhead design. The logical conclusion to the CTTP is to validate these various technologies to a Technology Readiness Level (TRL) of 6 through the proposed structural test program. The CTTP supports the advancement of key enabling technologies required for aluminum lithium cryogenic tanks. The technologies are focused towards innovative and low cost manufacturing processes such as near net shape technologies: one piece spun formed domes, extruded barrel panels, and one piece roll forged ring frames. Other innovative technologies include the friction stir weld process and weight-efficient low profile bulkhead designs. All of these technologies are of primary importance for NASA's mission plan for reusable and expendable launch vehicles. This program fills the niche for an all 2195 aluminum lithium alloy cryogenic tank which is not being covered by existing NASA technology work.

  6. Fission of Entangled Spins: An Electronic Structure Perspective

    NASA Astrophysics Data System (ADS)

    Feng, Xintian; Luzanov, Anatoliy; Krylov, Anna

    2014-03-01

    Electronic structure aspects of singlet fission process are discussed. Correlated adiabatic wave functions of the bright singlet and dark multiexciton states of tetracene and pentacene dimers are analyzed in terms of their character (excitonic, charge-resonance, multiexciton). At short interfragment separation (3.5-4.0 angstroms), both multiexcitonic and singly-excited singlet states have noticeable charge-resonance contributions that fall off quickly at longer distances. Non-adiabatic couplings between the states are discussed. The limitations of diabatic framework in the context of singlet fission are explained. Based on the Cauchy-Schwarz inequality, we propose using the norm of one-particle transition density matrix, | | γ | | , as a proxy for couplings. The analysis of | | γ | | and state characters reveals that the couplings between the multiexciton and singly-excited states depend strongly on the weights of charge-resonance configurations in these states. To characterize energetics relevant to triplets separation step, we consider multiexciton binding energy (Eb) defined as the difference between the quintet and singlet multiexciton states. The effect of fragment orientation on the couplings and Eb is analyzed.

  7. Identification and brief treatment of alcohol problems with medical patients: an international perspective.

    PubMed

    Barnett, Nancy P; Monti, Peter M; Cherpitel, Cheryl; Bendtsen, Preben; Borges, Guilherme; Colby, Suzanne M; Nordqvist, Cecilia; Johansson, Kjell

    2003-02-01

    This article summarizes the proceedings of a symposium at the 2002 RSA meeting in San Francisco, California. The chair was Peter Monti and co-chair was Nancy Barnett. The aim of the symposium was to bring together researchers from the United States, Sweden, and Mexico to present current findings on the development and implementation of screening and intervention research in Emergency Departments (ED). Cheryl Cherpitel presented findings on the performance of the Rapid Alcohol Problems Screen (RAPS4), a 4-item instrument used for screening for alcohol dependence and harmful drinking in the ED. Dr. Cherpitel also presented for her collaborator, Guilherme Borges, their research on the performance of a number of screening measures including the RAPS among Mexicans and Mexican-Americans with alcohol-related disorders in the ED. Preben Bendtsen described the implementation of an alcohol screening and intervention procedure delivered by ordinary ED staff in Sweden. Nancy Barnett presented data on characteristics related to readiness to change alcohol use in a sample of young adults who were treated in an ED for injury or intoxication. PMID:12605075

  8. Debates—Perspectives on socio-hydrology: Modeling flood risk as a public policy problem

    NASA Astrophysics Data System (ADS)

    Gober, Patricia; Wheater, Howard S.

    2015-06-01

    Socio-hydrology views human activities as endogenous to water system dynamics; it is the interaction between human and biophysical processes that threatens the viability of current water systems through positive feedbacks and unintended consequences. Di Baldassarre et al. implement socio-hydrology as a flood risk problem using the concept of social memory as a vehicle to link human perceptions to flood damage. Their mathematical model has heuristic value in comparing potential flood damages in green versus technological societies. It can also support communities in exploring the potential consequences of policy decisions and evaluating critical policy tradeoffs, for example, between flood protection and economic development. The concept of social memory does not, however, adequately capture the social processes whereby public perceptions are translated into policy action, including the pivotal role played by the media in intensifying or attenuating perceived flood risk, the success of policy entrepreneurs in keeping flood hazard on the public agenda during short windows of opportunity for policy action, and different societal approaches to managing flood risk that derive from cultural values and economic interests. We endorse the value of seeking to capture these dynamics in a simplified conceptual framework, but favor a broader conceptualization of socio-hydrology that includes a knowledge exchange component, including the way modeling insights and scientific results are communicated to floodplain managers. The social processes used to disseminate the products of socio-hydrological research are as important as the research results themselves in determining whether modeling is used for real-world decision making.

  9. Studies on clonogenic hemopoietic cells of vertebrate in space: problems and perspectives

    NASA Astrophysics Data System (ADS)

    Domaratskaya, E. I.; Michurina, T. V.; Bueverova, E. I.; Bragina, E. V.; Nikonova, T. A.; Starostin, V. I.; Khrushchov, N. G.

    Hemopoietic tissues were studied in vertebrates launched aboard the Soviet (Russian) biosatellites ("Cosmos-1129, 1514, 1667, 1887 and 2044"; "Bion-10 and 11") between 1980 and 1996. In the bone marrow of rats exposed to spaceflight conditions, a statistically significant decrease in cell number was revealed in the progenitor cell compartment accounting for the compensatory response of granulocyte—macrophage (CFU-gm) and erythrocyte lineages (BFU-e and CFU-e) and in the compartment of multipotent hemopoietic stem cells (CFU-s), which is responsible for the permanent renewal of hemopoietic tissue. The number of stromal fibroblastic progenitors (CFC-f) in the bone marrow of these rats was also reduced. Apparently, changes in the hemopoietic stroma damage the hemopoietic microenvironment and, hence, may be responsible for changes observed in the hemopoietic tissue proper. Attempts were made to develop methods for analyzing morphologically indiscernible clonogenic hemopoietic cells of newts, and studies on the effects of spaceflight factors on these cells were performed. The results showed that the numbers of clonogenic cells in newts of the flight group newts were significantly lower than in control newts. The data obtained are used as the basis for formulating the problems to be studied, drawing up a program for further research on the effects of spaceflight factors on stem and other clonogenic hemopoietic cells, and developing new experimental models for analyzing stem cells, the state of the hemopoietic stroma, etc.

  10. Richat Structure, Mauritania, Perspective View, Landsat Image over SRTM Elevation

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This prominent circular feature, known as the Richat Structure, in the Sahara desert of Mauritania is often noted by astronauts because it forms a conspicuous 50-kilometer-wide (30-mile-wide) bull's-eye on the otherwise rather featureless expanse of the desert. Initially mistaken for a possible impact crater, it is now known to be an eroded circular anticline (structural dome) of layered sedimentary rocks.

    Extensive sand dunes occur in this region and the interaction of bedrock topography, wind, and moving sand is evident in this scene. Note especially how the dune field ends abruptly short of the cliffs at the far right as wind from the northeast (lower right) apparently funnels around the cliff point, sweeping clean areas near the base of the cliff. Note also the small isolated peak within the dune field. That peak captures some sand on its windward side, but mostly deflects the wind and sand around its sides, creating a sand-barren streak that continues far downwind.

    This view was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view uses a 6-times vertical exaggeration to greatly enhance topographic expression. For vertical scale, note that the height of the mesa ridge in the back center of the view is about 285 meters (about 935 feet) tall. Colors of the scene were enhanced by use of a combination of visible and infrared bands, which helps to differentiate bedrock (browns), sand (yellow, some white), minor vegetation in drainage channels (green), and salty sediments (bluish whites). Some shading of the elevation model was included to further highlight the topographic features.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR

  11. Plant centromeric retrotransposons: a structural and cytogenetic perspective

    PubMed Central

    2011-01-01

    Background The centromeric and pericentromeric regions of plant chromosomes are colonized by Ty3/gypsy retrotransposons, which, on the basis of their reverse transcriptase sequences, form the chromovirus CRM clade. Despite their potential importance for centromere evolution and function, they have remained poorly characterized. In this work, we aimed to carry out a comprehensive survey of CRM clade elements with an emphasis on their diversity, structure, chromosomal distribution and transcriptional activity. Results We have surveyed a set of 190 CRM elements belonging to 81 different retrotransposon families, derived from 33 host species and falling into 12 plant families. The sequences at the C-terminus of their integrases were unexpectedly heterogeneous, despite the understanding that they are responsible for targeting to the centromere. This variation allowed the division of the CRM clade into the three groups A, B and C, and the members of each differed considerably with respect to their chromosomal distribution. The differences in chromosomal distribution coincided with variation in the integrase C-terminus sequences possessing a putative targeting domain (PTD). A majority of the group A elements possess the CR motif and are concentrated in the centromeric region, while members of group C have the type II chromodomain and are dispersed throughout the genome. Although representatives of the group B lack a PTD of any type, they appeared to be localized preferentially in the centromeres of tested species. All tested elements were found to be transcriptionally active. Conclusions Comprehensive analysis of the CRM clade elements showed that genuinely centromeric retrotransposons represent only a fraction of the CRM clade (group A). These centromeric retrotransposons represent an active component of centromeres of a wide range of angiosperm species, implying that they play an important role in plant centromere evolution. In addition, their transcriptional activity

  12. Evidence of Second-Order Factor Structure in a Diagnostic Problem Space: Implications for Medical Education.

    ERIC Educational Resources Information Center

    Papa, Frank J.; And Others

    1997-01-01

    Chest pain was identified as a specific medical problem space, and disease classes were modeled to define it. Results from a test taken by 628 medical residents indicate a second-order factor structure that suggests that chest pain is a multidimensional problem space. Implications for medical education are discussed. (SLD)

  13. Ill-Structured Problem Solving of Novice Reading Specialists and Expert Assessment Specialists: Learning and Expertise

    ERIC Educational Resources Information Center

    Currie-Rubin, Rachel

    2012-01-01

    This dissertation examines the problem-solving processes of seven graduate student novices enrolled in a course in educational assessment and ten educational assessment experts. Using Jonassen's (1997) ill- and well-structured problem-solving frameworks, I analyze think-aloud protocols of experts and novices as they examine ill-structured…

  14. How Instructional Design Experts Use Knowledge and Experience to Solve Ill-Structured Problems

    ERIC Educational Resources Information Center

    Ertmer, Peggy A.; Stepich, Donald A.; York, Cindy S.; Stickman, Ann; Wu, Xuemei (Lily); Zurek, Stacey; Goktas, Yuksel

    2008-01-01

    This study examined how instructional design (ID) experts used their prior knowledge and previous experiences to solve an ill-structured instructional design problem. Seven experienced designers used a think-aloud procedure to articulate their problem-solving processes while reading a case narrative. Results, presented in the form of four…

  15. Structural Variables That Determine Problem-Solving Difficulty in Computer Assisted Instruction

    ERIC Educational Resources Information Center

    Loftus, Elizabeth F.; Suppes, Patrick

    1972-01-01

    Analysis showed that a word problem is difficult to solve if: it is of a different type from the problem that preceded it; its solution requires a large number of different operations; its surface structure is complex; it has a large number of words; or it requires a conversion of units. (Authors)

  16. Perceptual Learning in Early Mathematics: Interacting with Problem Structure Improves Mapping, Solving and Fluency

    ERIC Educational Resources Information Center

    Thai, Khanh-Phuong; Son, Ji Y.; Hoffman, Jessica; Devers, Christopher; Kellman, Philip J.

    2014-01-01

    Mathematics is the study of structure but students think of math as solving problems according to rules. Students can learn procedures, but they often have trouble knowing when to apply learned procedures, especially to problems unlike those they trained with. In this study, the authors rely on the psychological mechanism of perceptual learning…

  17. Structured Parenting of Toddlers at High versus Low Genetic Risk: Two Pathways to Child Problems

    ERIC Educational Resources Information Center

    Leve, Leslie D.; Harold, Gordon T.; Ge, Xiaojia; Neiderhiser, Jenae M.; Shaw, Daniel; Scaramella, Laura V.; Reiss, David

    2009-01-01

    Objective: Little is known about how parenting might offset genetic risk to prevent the onset of child problems during toddlerhood. We used a prospective adoption design to separate genetic and environmental influences and test whether associations between structured parenting and toddler behavior problems were conditioned by genetic risk for…

  18. Preparation of biosilica structures from frustules of diatoms and their applications: current state and perspectives.

    PubMed

    Wang, Yu; Cai, Jun; Jiang, Yonggang; Jiang, Xinggang; Zhang, Deyuan

    2013-01-01

    Frustules, the silica shells of diatoms, have unique porous architectures with good mechanical strength. In recent years, biologists have learned more about the mechanism of biosilica shells formation; meanwhile, physicists have revealed their optical and microfluidic properties, and chemists have identified ways to modify them into various materials while maintaining their hierarchical structures. These efforts have provided more opportunities to use biosilica structures in microsystems and other commercial products. This review focuses on the preparation of biosilica structures and their applications, especially in the development of microdevices. We discuss existing methods of extracting biosilica from diatomite and diatoms, introduce methods of separating biosilica structures by shape and sizes, and summarize recent studies on diatom-based devices used for biosensing, drug delivery, and energy applications. In addition, we introduce some new findings on diatoms, such as the elastic deformable characteristics of biosilica structures, and offer perspectives on planting diatom biosilica in microsystems. PMID:23179621

  19. Geographic Variation in Plant Community Structure of Salt Marshes: Species, Functional and Phylogenetic Perspectives

    PubMed Central

    Guo, Hongyu; Chamberlain, Scott A.; Elhaik, Eran; Jalli, Inder; Lynes, Alana-Rose; Marczak, Laurie; Sabath, Niv; Vargas, Amy; Więski, Kazimierz; Zelig, Emily M.; Pennings, Steven C.

    2015-01-01

    In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in

  20. Packing, Scheduling and Covering Problems in a Game-Theoretic Perspective

    NASA Astrophysics Data System (ADS)

    Karlstrom, Leif

    Magma transport pathways through Earth's crust span 12--15 orders of magnitude in time and space, with unsteadiness at all scales. However emergent organization of this system is widespread, recorded by spatial loci of volcanism at the surface and large-scale, rapid outpourings of magma throughout the geologic record. This thesis explores several mechanisms for the organization and time evolution of magma transport, from the deep crust to the surface. A primary focus (Chapters 2--5) is the filling, stability and drainage of magma chambers, structures which function both as reservoirs feeding individual volcanic eruptions and as stalling points in the crust where magma accumulates and differentiation occurs. We show that magma chambers may dictate the spatio-temporal organization of magma rising through crust (Chapters 2--3), control the surface eruptive progression of extreme mantle melting events (Chapter 4), and actively set the size of calderas that form during shallow, crystal rich eruptions (Chapter 5). Each of these chapters explores variations on a hypothesis: interactions between magma chamber stresses and the rheology of surrounding crustal materials evolve during magma transport and this unsteady process helps determine the magnitude, location, and timing of surface eruptions. The last part of this thesis (Chapters 6--7) focuses on surface transport processes, the meandering of melt channels on the surface of glaciers and lava flows. We show that the meandering instability is a generic feature of flow over an erodable substrate, despite significantly different fluid characteristics and erosion mechanics.

  1. Outpatients' Perspectives on Problems and Needs Related to Female Genital Mutilation/Cutting: A Qualitative Study from Somaliland

    PubMed Central

    Fried, Sarah; Mahmoud Warsame, Amina; Berggren, Vanja; Isman, Elisabeth; Johansson, Annika

    2013-01-01

    Aim. To explore female outpatients' perspectives on problems related to female genital mutilation/cutting (FGM/C) and their views on information, care, and counseling. Setting. An FGM/C support center at a maternity clinic in Hargeisa, Somaliland. Methods. A qualitative, descriptive study, using content analysis of seven semistructured interviews with female outpatients. Results. All participants had been ignorant of the etiology of their FGM/C-related complications and hesitant to seek care. All had undergone infibulation but did not wish the same for their daughters. In recent years they had learnt through religious leaders and media campaigns that infibulation was unapproved by Islam. A less severe FGM/C type, “Sunna,” was more accepted; however, few could define what “Sunna” meant. Condemning and ridiculing attitudes against uncircumcised women prevailed in their community. Conclusions. New ideas and concepts related to FGM/C enter the common discourse in the Somali society while traditional norms and values still prevail. Religion was shown to have a strong impact on FGM/C practices and beliefs. Interventions aiming to raise awareness of health consequences of all types of FGM/C, as well as where to seek care for complications, are needed in Somaliland. Involvement of religious leaders in anti-FGM/C programs is essential. PMID:24151505

  2. US EPA (Environmental Protection Agency) perspective on AOC (assimilable organic carbon) research as related to coliform colonization and compliance problems

    SciTech Connect

    Reasoner, D.J.; Rice, E.W.

    1989-01-01

    The biological stability of treated drinking water has become a major concern for water utilities. The U.S. E.P.A. is concerned from the perspective of coliform MCL compliance and remediation of coliform biofilm problems. The levels of readily assimilable nutrients present in treated water are affected by water treatment processes, but of greatest concern are those processes, such as ozonation, that cause increases in the levels of assimilable organic carbon (AOC) and therefore contribute to biological instability of the water. Thus, the combined use of ozonation (pre-oxidant) and a lower disinfectant residual as an approach to reducing disinfectant byproducts may result in increased bacterial growth, including coliforms, in the distribution system. Information is needed on: the AOC flux level that stimulate coliform growth in biofilm: the specific nutrients and concentrations that can stimulate growth of both coliforms and HPC; treatment strategies to reduce AOC levels and strategies to effectively control biofilm formation where AOC levels cannot be reduced.

  3. The problems of offenders with mental disorders: a plurality of perspectives within a single mental health care organisation.

    PubMed

    Davies, Jacqueline P; Heyman, Bob; Godin, Paul M; Shaw, Monica P; Reynolds, Lisa

    2006-08-01

    Managers, doctors, nurses, occupational therapists, social workers, psychologists, unqualified staff and service users were interviewed for a qualitative study of risk management and rehabilitation in an inner city medium secure forensic mental health care unit. Different professional orientations to service user problems were identified. Doctors focused primarily on the diagnosis of mental disorder, which they managed mainly through pharmaceutical interventions. Psychologists were principally concerned with personal factors, for example service user insight into their biographical history. Occupational therapists concentrated mainly on daily living skills, and social workers on post-discharge living arrangements. Some front line nurses, held accountable for security lapses, adopted a criminogenic approach. Service users were more likely than professionals to understand their needs in terms of their wider life circumstances. These differences are explored qualitatively in relation to four models of crossdisciplinary relationships: monoprofessional self-organisation combined with restricted communication; hermeneutic reaching out to other perspectives; the establishment of interdisciplinary sub-systems; and transdisciplinary merger. Relationships between professions working in this unit, as portrayed in qualitative interviews, corresponded mainly to the first model of monoprofessional self-organisation. Reasons for restricted crossdisciplinary understanding, particularly the wide power/status differences between the medical and other professions, and between staff and patients, are discussed. PMID:16690185

  4. Outpatients' perspectives on problems and needs related to female genital mutilation/cutting: a qualitative study from somaliland.

    PubMed

    Fried, Sarah; Mahmoud Warsame, Amina; Berggren, Vanja; Isman, Elisabeth; Johansson, Annika

    2013-01-01

    Aim. To explore female outpatients' perspectives on problems related to female genital mutilation/cutting (FGM/C) and their views on information, care, and counseling. Setting. An FGM/C support center at a maternity clinic in Hargeisa, Somaliland. Methods. A qualitative, descriptive study, using content analysis of seven semistructured interviews with female outpatients. Results. All participants had been ignorant of the etiology of their FGM/C-related complications and hesitant to seek care. All had undergone infibulation but did not wish the same for their daughters. In recent years they had learnt through religious leaders and media campaigns that infibulation was unapproved by Islam. A less severe FGM/C type, "Sunna," was more accepted; however, few could define what "Sunna" meant. Condemning and ridiculing attitudes against uncircumcised women prevailed in their community. Conclusions. New ideas and concepts related to FGM/C enter the common discourse in the Somali society while traditional norms and values still prevail. Religion was shown to have a strong impact on FGM/C practices and beliefs. Interventions aiming to raise awareness of health consequences of all types of FGM/C, as well as where to seek care for complications, are needed in Somaliland. Involvement of religious leaders in anti-FGM/C programs is essential. PMID:24151505

  5. Palaeo sea-level and ice-sheet databases: problems, strategies and perspectives

    NASA Astrophysics Data System (ADS)

    Rovere, Alessio; Düsterhus, André; Carlson, Anders; Barlow, Natasha; Bradwell, Tom; Dutton, Andrea; Gehrels, Roland; Hibbert, Fiona; Hijma, Marc; Horton, Benjamin; Klemann, Volker; Kopp, Robert; Sivan, Dorit; Tarasov, Lev; Törnqvist, Torbjorn

    2016-04-01

    Databases of palaeoclimate data have driven many major developments in understanding the Earth system. The measurement and interpretation of palaeo sea-level and ice-sheet data that form such databases pose considerable challenges to the scientific communities that use them for further analyses. In this paper, we build on the experience of the PALSEA (PALeo constraints on SEA level rise) community, which is a working group inside the PAGES (Past Global Changes) project, to describe the challenges and best strategies that can be adopted to build a self-consistent and standardised database of geological and geochemical data related to palaeo sea levels and ice sheets. Our aim in this paper is to identify key points that need attention and subsequent funding when undertaking the task of database creation. We conclude that any sea-level or ice-sheet database must be divided into three instances: i) measurement; ii) interpretation; iii) database creation. Measurement should include postion, age, description of geological features, and quantification of uncertainties. All must be described as objectively as possible. Interpretation can be subjective, but it should always include uncertainties and include all the possible interpretations, without unjustified a priori exclusions. We propose that, in the creation of a database, an approach based on Accessibility, Transparency, Trust, Availability, Continued updating, Completeness and Communication of content (ATTAC3) must be adopted. Also, it is essential to consider the community structure that creates and benefits of a database. We conclude that funding sources should consider to address not only the creation of original data in specific research-question oriented projects, but also include the possibility to use part of the funding for IT-related and database creation tasks, which are essential to guarantee accessibility and maintenance of the collected data.

  6. Exploring the views of people with mental health problems' on the concept of coercion: Towards a broader socio-ethical perspective.

    PubMed

    Norvoll, Reidun; Pedersen, Reidar

    2016-05-01

    In mental health care, coercion is a controversial issue that has led to much debate and research on its nature and use. Yet, few previous studies have explicitly explored the views on the concept of coercion among people with first-hand experiences of being coerced. This study includes semi-structured focus-groups and individual interviews with 24 participants who had various mental health problems and experiences with coercion. Data were collected in 2012-2013 in three regions of Norway and analysed by a thematic content analysis. Findings show that participants had wide-ranging accounts of coercion, including formal and informal coercion across health- and welfare services. They emphasised that using coercion reflects the mental health system's tendency to rely on coercion and the lack of voluntary services and treatment methods that are more helpful. Other core characteristics of coercion were deprivation of freedom, power relations, in terms of powerlessness and 'counter-power,' and coercion as existential and social life events. Participants' views are consistent with prevailing theories of coercion and research on perceived coercion. However, this study demonstrates a need for broader existential and socio-ethical perspectives on coercion that are intertwined with treatment and care systems in research and practice. Implications for mental health policy and services are discussed. PMID:27054304

  7. Main problems and perspectives of the synthesis of nanocomposite coatings on the surface of complex-shaped components

    NASA Astrophysics Data System (ADS)

    Brzhozovskii, B.; Martynov, V.; Zinina, E.; Brovkova, M.

    2016-02-01

    The main methods for composite coating synthesis in the surface layer of complex-shaped workpiece with dissipative properties have been investigated in this study. The problem of their application can be solved by using low-temperature plasma of combined discharge. The plasma is formed directly around the treated surface, which allows the use of the maximum amount of energy transmitted by its ions for the synthesis process itself. The main mechanism is the synthesis of three-body recombination, in which surface structures are heated to temperatures that change the phase of their constituent atoms. As a result, the original structure of the surface layer of the workpiece is transformed into a composite structure consisting of nanoclusters of ∼ 50 ... 100 nm in size and an amorphous layer of particles which acts as binder, and gradient transition from the coating to the base material filling the microvoids.

  8. An integer programming approach to the phase problem for centrosymmetric structures.

    PubMed

    Vaia, Anastasia; Sahinidis, Nikolaos V

    2003-09-01

    The problem addressed in this paper is the determination of three-dimensional structures of centrosymmetric crystals from X-ray diffraction measurements. The 'minimal principle' that a certain quantity is minimized only by the crystal structure is employed to solve the phase problem. The mathematical formulation of the minimal principle is a nonconvex nonlinear optimization problem. To date, local optimization techniques and advanced computer architectures have been used to solve this problem, which may have a very large number of local optima. In this paper, the minimal principle model is reformulated for the case of centrosymmetric structures into an integer programming problem in terms of the missing phases. This formulation is solvable by well established combinatorial optimization techniques that are guaranteed to provide the global optimum in a finite number of steps without explicit enumeration of all possible combinations of phases. Computational experience with the proposed method on a number of structures of moderate complexity is provided and demonstrates that the approach yields a fast and reliable method that resolves the crystallographic phase problem for the case of centrosymmetric structures. PMID:12944609

  9. Problems of Access in the Context of Academic Structures. Yale Higher Education Program Working Paper.

    ERIC Educational Resources Information Center

    Clark, Burton R.

    We need conceptual assistance in thinking about access to higher education, systematic categories that will help us analyze and compare the national academic structures that condition problems of access and solutions thereto. An approach that centers on basic structure directs attention to the heavy historical momentum of massive systems of higher…

  10. The Influence of Science Knowledge Structures on Children's Success in Solving Academic Problems.

    ERIC Educational Resources Information Center

    Champagne, Audrey B.; And Others

    Presented is a study of eighth-grade students' academic problem-solving ability based on their knowledge structures, or their information stored in semantic or long-term memory. The authors describe a technique that they developed to probe knowledge structures with an extension of the card-sort method. The method, known as the Concept Structure…

  11. Analysis, preliminary design and simulation systems for control-structure interaction problems

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alvin, Kenneth F.

    1991-01-01

    Software aspects of control-structure interaction (CSI) analysis are discussed. The following subject areas are covered: (1) implementation of a partitioned algorithm for simulation of large CSI problems; (2) second-order discrete Kalman filtering equations for CSI simulations; and (3) parallel computations and control of adaptive structures.

  12. Opportunity Structure for Gambling and Problem Gambling among Employees in the Transport Industry

    ERIC Educational Resources Information Center

    Revheim, Tevje; Buvik, Kristin

    2009-01-01

    Working conditions for employees in the transport sector might present an opportunity structure for gambling by providing access to gambling during the workday. This study investigates connections between opportunity structure, gambling during the workday, and gambling problems among employees in the transport sector. Data has been collected from…

  13. Perspective: Structural dynamics in condensed matter mapped by femtosecond x-ray diffraction

    SciTech Connect

    Elsaesser, T.; Woerner, M.

    2014-01-14

    Ultrashort soft and hard x-ray pulses are sensitive probes of structural dynamics on the picometer length and femtosecond time scales of electronic and atomic motions. Recent progress in generating such pulses has initiated new directions of condensed matter research, exploiting a variety of x-ray absorption, scattering, and diffraction methods to probe photoinduced structural dynamics. Atomic motion, changes of local structure and long-range order, as well as correlated electron motion and charge transfer have been resolved in space and time, providing a most direct access to the physical mechanisms and interactions driving reversible and irreversible changes of structure. This perspective combines an overview of recent advances in femtosecond x-ray diffraction with a discussion on ongoing and future developments.

  14. Perspectives of solution NMR spectroscopy for structural and functional studies of integral membrane proteins

    NASA Astrophysics Data System (ADS)

    Reckel, Sina; Hiller, Sebastian

    2013-04-01

    This article discusses future perspectives of solution NMR spectroscopy to study structures and functions of integral membrane proteins at atomic resolution, based on a review of recent progress in this area. Several selected examples of structure determinations, as well as functional studies of integral membrane proteins are highlighted. We expect NMR spectroscopy to make future key scientific contributions to understanding membrane protein function, in particular for large membrane protein systems with known three-dimensional structure. Such situations can benefit from the fact that functional NMR studies have substantially less limitations by molecular size than a full de novo structure determination. Therefore, the general potential for NMR spectroscopy to solve biologic key questions associated with integral membrane proteins is very promising.

  15. Exact solution to the problem of N bodies forming a multi-layer rotating structure.

    PubMed

    Smulsky, Joseph J

    2015-01-01

    Exact solutions to the problem of the Newtonian gravitational interaction of N material points moving around N 2 concentric circular orbits are considered. Each circular orbit contains N 3 axisymmetrically located bodies having identical masses. The structure as a whole rotates around its symmetry axis. Such structures are identical to the homographic-dynamics configurations, or planar central configurations, known from literature. Conceptually, those structures can be considered as structures formed by mutually embedded polygons with point bodies placed at polygon vortices. For structures involving less than 20 bodies, solutions were obtained using Hamiltonian-mechanics methods. In the study, the forces acting on each body in the rotating structure from the side of all other bodies were found. The differential motion equations of the bodies were reduced to a system of linear algebraic equations for the body masses. Solutions in various forms were obtained. For specifying the initial parameters and for calculating all other characteristics of the structures, a computer program RtCrcSt2.for has been developed. Structures comprising up to one million bodies have been calculated. Graphical images of obtained structures are presented, and their properties are described. Stability problems for examined structures are considered, and possible application of obtained results to celestial- and space-mechanics problems is discussed. PMID:26203407

  16. Finite element analysis of structural engineering problems using a viscoplastic model incorporating two back stresses

    NASA Technical Reports Server (NTRS)

    Arya, Vinod K.; Halford, Gary R.

    1993-01-01

    The feasibility of a viscoplastic model incorporating two back stresses and a drag strength is investigated for performing nonlinear finite element analyses of structural engineering problems. To demonstrate suitability for nonlinear structural analyses, the model is implemented into a finite element program and analyses for several uniaxial and multiaxial problems are performed. Good agreement is shown between the results obtained using the finite element implementation and those obtained experimentally. The advantages of using advanced viscoplastic models for performing nonlinear finite element analyses of structural components are indicated.

  17. Family Structure and Adolescent Alcohol Use Problems: Extending Popular Explanations to American Indiansc

    PubMed Central

    Eitle, Tamela McNulty; Johnson-Jennings, Michelle; Eitle, David J.

    2013-01-01

    Competing explanations of the relationship between family structure and alcohol use problems are examined using a sample of American Indian adolescents from the National Longitudinal Study of Adolescent Health. Living in a single-parent family is found to be a marker for the unequal distribution of stress exposure and parental alcohol use, but the effects of other family structures like non-parent families and the presence of under 21-year-old extended family or non-family members emerge or remain as risk or protective factors for alcohol use problems after a consideration of SES, family processes, peer socialization, and social stress. In particular, a non-parent family structure that has not been considered in prior research emerged as a protective family structure for American Indian adolescent alcohol use problems. PMID:24014896

  18. The Transition to Preschool: A Problem or an Opportunity for Children? A Sociological Perspective in the Context of a "Split System"

    ERIC Educational Resources Information Center

    Amerijckx, Gaëlle; Humblet, Perrine C.

    2015-01-01

    This article discusses the central issue of the transition to preschool. Individual semi-structured interviews with school professionals and parents in the Brussels region revealed that this issue is crucial for the well-being of young children, from both an educational and a social perspective. We discovered that the education system works under…

  19. Problems in functioning from the patient perspective using the International Classification of Functioning, Disability and Health (ICF) as a reference.

    PubMed

    Gradinger, Felix; Köhler, Barbara; Khatami, Ramin; Mathis, Johannes; Cieza, Alarcos; Bassetti, Claudio

    2011-03-01

    We conducted a qualitative, multicenter study using a focus group design to explore the lived experiences of persons with any kind of primary sleep disorder with regard to functioning and contextual factors using six open-ended questions related to the International Classification of Functioning, Disability and Health (ICF) components. We classified the results using the ICF as a frame of reference. We identified the meaningful concepts within the transcribed data and then linked them to ICF categories according to established linking rules. The six focus groups with 27 participants yielded a total of 6986 relevant concepts, which were linked to a total of 168 different second-level ICF categories. From the patient perspective, the ICF components: (1) Body Functions; (2) Activities & Participation; and (3) Environmental Factors were equally represented; while (4) Body Structures appeared poignantly less frequently. Out of the total number of concepts, 1843 concepts (26%) were assigned to the ICF component Personal Factors, which is not yet classified but could indicate important aspects of resource management and strategy development of those who have a sleep disorder. Therefore, treatment of patients with sleep disorders must not be limited to anatomical and (patho-)physiological changes, but should also consider a more comprehensive view that includes patient's demands, strategies and resources in daily life and the contextual circumstances surrounding the individual. PMID:20642749

  20. Formal analysis, hardness, and algorithms for extracting internal structure of test-based problems.

    PubMed

    Jaśkowski, Wojciech; Krawiec, Krzysztof

    2011-01-01

    Problems in which some elementary entities interact with each other are common in computational intelligence. This scenario, typical for coevolving artificial life agents, learning strategies for games, and machine learning from examples, can be formalized as a test-based problem and conveniently embedded in the common conceptual framework of coevolution. In test-based problems, candidate solutions are evaluated on a number of test cases (agents, opponents, examples). It has been recently shown that every test of such problem can be regarded as a separate objective, and the whole problem as multi-objective optimization. Research on reducing the number of such objectives while preserving the relations between candidate solutions and tests led to the notions of underlying objectives and internal problem structure, which can be formalized as a coordinate system that spatially arranges candidate solutions and tests. The coordinate system that spans the minimal number of axes determines the so-called dimension of a problem and, being an inherent property of every problem, is of particular interest. In this study, we investigate in-depth the formalism of a coordinate system and its properties, relate them to properties of partially ordered sets, and design an exact algorithm for finding a minimal coordinate system. We also prove that this problem is NP-hard and come up with a heuristic which is superior to the best algorithm proposed so far. Finally, we apply the algorithms to three abstract problems and demonstrate that the dimension of the problem is typically much lower than the number of tests, and for some problems converges to the intrinsic parameter of the problem--its a priori dimension. PMID:21815770

  1. ATLAS, an integrated structural analysis and design system. Volume 5: System demonstration problems

    NASA Technical Reports Server (NTRS)

    Samuel, R. A. (Editor)

    1979-01-01

    One of a series of documents describing the ATLAS System for structural analysis and design is presented. A set of problems is described that demonstrate the various analysis and design capabilities of the ATLAS System proper as well as capabilities available by means of interfaces with other computer programs. Input data and results for each demonstration problem are discussed. Results are compared to theoretical solutions or experimental data where possible. Listings of all input data are included.

  2. Approximate analysis for repeated eigenvalue problems with applications to controls-structure integrated design

    NASA Technical Reports Server (NTRS)

    Kenny, Sean P.; Hou, Gene J. W.

    1994-01-01

    A method for eigenvalue and eigenvector approximate analysis for the case of repeated eigenvalues with distinct first derivatives is presented. The approximate analysis method developed involves a reparameterization of the multivariable structural eigenvalue problem in terms of a single positive-valued parameter. The resulting equations yield first-order approximations to changes in the eigenvalues and the eigenvectors associated with the repeated eigenvalue problem. This work also presents a numerical technique that facilitates the definition of an eigenvector derivative for the case of repeated eigenvalues with repeated eigenvalue derivatives (of all orders). Examples are given which demonstrate the application of such equations for sensitivity and approximate analysis. Emphasis is placed on the application of sensitivity analysis to large-scale structural and controls-structures optimization problems.

  3. Effects of problem structure and dialogue type on the performance of the man/machine interface

    SciTech Connect

    Palko, J.B.

    1986-01-01

    This research project is intended to provide guidance for software designers who must decide on a dialogue style for interactive problem solving support for new or infrequent users. In addition, it examines the relative performance of these dialogues in environments with a varying amount of problem structure. The three dialogue styles that are recommended by various writers in the field of information systems are: (1) menu driven, (2) question/response, and (3) form filling. It is concluded that if an interface is properly designed it probably does not matter which dialogue style is used in some problem settings. It is also clear that adding problem parameters reduces the ability of the problem solver to determine the best solution.

  4. Solution theorems for the standard eigenvalue problem of structures with uncertain-but-bounded parameters

    NASA Astrophysics Data System (ADS)

    Qiu, Zhiping; Wang, Xiaojun

    2005-04-01

    Generalized eigenvalue problems from the modal analysis are often converted to the standard eigenvalue problems. In this paper, it evaluates the upper and lower bounds on the eigenvalues of the standard eigenvalue problem of structures subject to severely deficient information about the structural parameters. Here, we focus on non-probabilistic interval analysis models of uncertainty, which are adapted to the case of severe lack of information on uncertainty. Non-probabilistic, interval analysis method in which uncertainties are defined by interval numbers appears as an alternative to the classical probabilistic models. For the standard eigenvalue problem of structures with uncertain-but-bounded parameters, the vertex solution theorem, the positive semi-definite solution theorem and the parameter decomposition solution theorem for the standard eigenvalue problem are presented, and compared with Deif's solution theorem in numerical examples. It is shown that, for the upper and lower bounds on the eigenvalues of the standard eigenvalue problem with uncertain-but-bounded parameters, the presented vertex solution theorem is unconditional, and the positive semi-definite solution theorem and the parameter decomposition solution theorem have less limitary conditions compared with Deif's solution theorem. The effectiveness of the vertex solution theorem, the positive semi-definite solution theorem and the parameter decomposition solution theorem are illustrated by numerical examples

  5. The management of a sexually charged clinical problem: social structural and psychoanalytic functionalist approaches in a therapeutic community.

    PubMed

    James, O W

    1986-03-01

    An event in a therapeutic community is examined from the perspectives of the structuralism of Durkheim and the functionalism of psychoanalysis. Although these two approaches might appear theoretically contradictory, analysis of the evidence shows them to be clinically complementary. The role of social structure in therapeutic communities requires deliberate conceptualization if such communities are to be demonstrably therapeutic. PMID:3964583

  6. Use of a structured descriptive assessment methodology to identify variables affecting problem behavior.

    PubMed Central

    Anderson, Cynthia M; Long, Ethan S

    2002-01-01

    This study evaluated a variation of functional assessment methodology, the structured descriptive assessment (SDA). The SDA is conducted in an individual's natural environment and involves systematically manipulating antecedent variables while leaving consequences free to vary. Results were evaluated by comparing the results of an SDA with results obtained from an analogue functional analysis with 4 children who exhibited problem behavior. For 3 of 4 participants, the results of the two assessments suggested similar hypotheses about variables maintaining problem behavior. Interventions based on the results of the SDA were implemented for 3 children and resulted in significant reductions in rates of problem behavior. PMID:12102134

  7. The Lie-Poisson structure of the symmetry reduced regularized n-body problem

    NASA Astrophysics Data System (ADS)

    Arunasalam, Suntharan; Dullin, Holger R.; Nguyen, Diana M. H.

    2015-02-01

    This paper investigates the symmetry reduction of the regularized n-body problem. The three body problem, regularized through quaternions, is examined in detail. We show that for a suitably chosen symmetry group action the space of quadratic invariants is closed and the Hamiltonian can be written in terms of the quadratic invariants. The corresponding Lie-Poisson structure is isomorphic to the Lie algebra u(3,3). Finally, we generalize this result to the n-body problem for n\\gt 3.

  8. Numerical investigation of transport mechanism in four-body problem using Lagrangian coherent structure

    NASA Astrophysics Data System (ADS)

    Qi, Rui; Huang, Biao

    2016-01-01

    Transport mechanism is critical for understanding natural phenomena in the solar system and is beneficial to space mission design. In this study, transport mechanism in the bicircular four-body problem is numerically explored by using Lagrangian coherent structure (LCS), a tool widely used for identifying transport barriers in fluid flow. First, equations of motion of the bicircular problem are derived and five topology configurations of forbidden region are presented. Then, definition and computational method of LCS are introduced. Finally, properties of LCS which are useful for revealing transport mechanism in the four-body problem are numerically investigated.

  9. A vorticity based approach to handle the fluid-structure interaction problems

    NASA Astrophysics Data System (ADS)

    Farahbakhsh, Iman; Ghassemi, Hassan; Sabetghadam, Fereidoun

    2016-02-01

    A vorticity based approach for the numerical solution of the fluid-structure interaction problems is introduced in which the fluid and structure(s) can be viewed as a continuum. Retrieving the vorticity field and recalculating a solenoidal velocity field, specially at the fluid-structure interface, are the kernel of the proposed algorithm. In the suggested method, a variety of constitutive equations as a function of left Cauchy-Green deformation tensor can be applied for modeling the structure domain. A nonlinear Mooney-Rivlin and Saint Venant-Kirchhoff model are expressed in terms of the left Cauchy-Green deformation tensor and the presented method is able to model the behavior of a visco-hyperelastic structure in the incompressible flow. Some numerical experiments, with considering the neo-Hookean model for structure domain, are executed and the results are validated via the available results from literature.

  10. Emotional and Behavioral Problems among Impoverished Kenyan Youth: Factor Structure and Sex-Differences

    PubMed Central

    Harder, Valerie S.; Mutiso, Victoria N.; Khasakhala, Lincoln I.; Burke, Heather M.; Rettew, David C.; Ivanova, Masha Y.; Ndetei, David M.

    2014-01-01

    Data on youth emotional and behavioral problems from societies in Sub-Saharan Africa are lacking. This may be due to the fact that few youth mental health assessments have been tested for construct validity of syndrome structure across multicultural societies that include developing countries, and almost none have been tested in Sub-Saharan Africa. The Youth Self-Report (YSR), for example, has shown great consistency of its syndrome structure across many cultures, yet data from only one developing country in Sub-Saharan Africa have been included. In this study, we test the factor structure of YSR syndromes among Kenyan youth ages 11–18 years from an informal settlement in Nairobi, Kenya and examine sex-differences in levels of emotional and behavioral problems. We find the eight syndrome structure of the YSR to fit these data well (Root Mean Square Error of Approximation=.049). While Kenyan girls have significantly higher internalizing (Anxious/Depressed, Withdrawn/Depressed, Somatic) problem scores than boys, these differences are of similar magnitude to published multicultural findings. The results support the generalizability of the YSR syndrome structure to Kenyan youth and are in line with multicultural findings supporting the YSR as an assessment of emotional and behavioral problems in diverse societies. PMID:25419046

  11. Understanding ill-structured engineering ethics problems through a collaborative learning and argument visualization approach.

    PubMed

    Hoffmann, Michael; Borenstein, Jason

    2014-03-01

    As a committee of the National Academy of Engineering recognized, ethics education should foster the ability of students to analyze complex decision situations and ill-structured problems. Building on the NAE's insights, we report about an innovative teaching approach that has two main features: first, it places the emphasis on deliberation and on self-directed, problem-based learning in small groups of students; and second, it focuses on understanding ill-structured problems. The first innovation is motivated by an abundance of scholarly research that supports the value of deliberative learning practices. The second results from a critique of the traditional case-study approach in engineering ethics. A key problem with standard cases is that they are usually described in such a fashion that renders the ethical problem as being too obvious and simplistic. The practitioner, by contrast, may face problems that are ill-structured. In the collaborative learning environment described here, groups of students use interactive and web-based argument visualization software called "AGORA-net: Participate - Deliberate!". The function of the software is to structure communication and problem solving in small groups. Students are confronted with the task of identifying possible stakeholder positions and reconstructing their legitimacy by constructing justifications for these positions in the form of graphically represented argument maps. The argument maps are then presented in class so that these stakeholder positions and their respective justifications become visible and can be brought into a reasoned dialogue. Argument mapping provides an opportunity for students to collaborate in teams and to develop critical thinking and argumentation skills. PMID:23420467

  12. Social problem solving among depressed adolescents is enhanced by structured psychotherapies

    PubMed Central

    Dietz, Laura J.; Marshal, Michael P.; Burton, Chad M.; Bridge, Jeffrey A.; Birmaher, Boris; Kolko, David; Duffy, Jamira N.; Brent, David A.

    2014-01-01

    Objective Changes in adolescent interpersonal behavior before and after an acute course of psychotherapy were investigated as outcomes and mediators of remission status in a previously described treatment study of depressed adolescents. Maternal depressive symptoms were examined as moderators of the association between psychotherapy condition and changes in adolescents’ interpersonal behavior. Method Adolescents (n = 63, mean age = 15.6 years, 77.8% female, 84.1% Caucasian) engaged in videotaped interactions with their mothers before randomization to cognitive behavior therapy (CBT), systemic behavior family therapy (SBFT), or nondirective supportive therapy (NST), and after 12–16 weeks of treatment. Adolescent involvement, problem solving and dyadic conflict were examined. Results Improvements in adolescent problem solving were significantly associated with CBT and SBFT. Maternal depressive symptoms moderated the effect of CBT, but not SBFT, on adolescents’ problem solving; adolescents experienced increases in problem solving only when their mothers had low or moderate levels of depressive symptoms. Improvements in adolescents’ problem solving were associated with higher rates of remission across treatment conditions, but there were no significant indirect effects of SBFT on remission status through problem solving. Exploratory analyses revealed a significant indirect effect of CBT on remission status through changes in adolescent problem solving, but only when maternal depressive symptoms at study entry were low. Conclusions Findings provide preliminary support for problem solving as an active treatment component of structured psychotherapies for depressed adolescents and suggest one Pathway by which maternal depression may disrupt treatment efficacy for depressed adolescents treated with CBT. PMID:24491077

  13. Structural fuzzy reliability analysis and its applications in strength problems for ships

    SciTech Connect

    Shao, W.

    1995-12-31

    In the universe there are two different kinds of uncertain phenomena: stochastic and fuzzy or vague. Both uncertain phenomena have been found in structural problems. Therefore, rational decisions concerning the design of marine structures cannot be made without resorting to the methods which can take the uncertainties into account. The fundamental concept of structural fuzzy reliability problems and the methods to give the fuzzy solution are introduced in the paper. Based on the principle of fuzzy decision-making the method to obtain the crisp solution of structural fuzzy reliability analysis is proposed by means of the Bound Search method. Illustrative numerical examples, ship bottom plates under slamming impact pressures are solved. The influence of variation of allowable tolerances in the fuzzy reliability indexes is discussed.

  14. A perspective on coherent structures and conceptual models for turbulent boundary layer physics

    NASA Technical Reports Server (NTRS)

    Robinson, Stephen K.

    1990-01-01

    Direct numerical simulations of turbulent boundary layers have been analyzed to develop a unified conceptual model for the kinematics of coherent motions in low Reynolds number canonical turbulent boundary layers. All classes of coherent motions are considered in the model, including low-speed streaks, ejections and sweeps, vortical structures, near-wall and outer-region shear layers, sublayer pockets, and large-scale outer-region eddies. The model reflects the conclusions from the study of the simulated boundary layer that vortical structures are directly associated with the production of turbulent shear stresses, entrainment, dissipation of turbulence kinetic energy, and the fluctuating pressure field. These results, when viewed from the perspective of the large body of published work on the subject of coherent motions, confirm that vortical structures may be considered the central dynamic element in the maintenance of turbulence in the canonical boundary layer. Vortical structures serve as a framework on which to construct a unified picture of boundary layer structure, providing a means to relate the many known structural elements in a consistent way.

  15. Response to Masafumi Ogawa, "Music Teacher Education in Japan: Structure, Problems, and Perspectives"

    ERIC Educational Resources Information Center

    Wheeler, Peggy

    2004-01-01

    Masafumi Ogawa's paper presents challenge after challenge facing the teacher and the teacher educator in Japan. One has the sense that a lifetime of frustrations with the national curriculum, the set-up of student teaching, and the definition of music as a school subject each made its way into the paper. Even choosing to focus on teacher training…

  16. Response to Masafumi Ogawa, "Music Teacher Education in Japan: Structure, Problems, and Perspectives"

    ERIC Educational Resources Information Center

    Hornbach, Christina

    2004-01-01

    Masafumi Ogawa cares deeply about improving music teacher education and has grave concerns about Japan's current music education and teacher training system. He notes reduced instructional time, cuts in teaching positions, and classroom management issues resulting in the devaluing of music education by administrators, students, and the general…

  17. A semi-implicit level set method for multiphase flows and fluid-structure interaction problems

    NASA Astrophysics Data System (ADS)

    Cottet, Georges-Henri; Maitre, Emmanuel

    2016-06-01

    In this paper we present a novel semi-implicit time-discretization of the level set method introduced in [8] for fluid-structure interaction problems. The idea stems from a linear stability analysis derived on a simplified one-dimensional problem. The semi-implicit scheme relies on a simple filter operating as a pre-processing on the level set function. It applies to multiphase flows driven by surface tension as well as to fluid-structure interaction problems. The semi-implicit scheme avoids the stability constraints that explicit scheme need to satisfy and reduces significantly the computational cost. It is validated through comparisons with the original explicit scheme and refinement studies on two-dimensional benchmarks.

  18. Lagrangian heuristic method for the wireless sensor network design problem in railway structural health monitoring

    NASA Astrophysics Data System (ADS)

    Hada, Akio; Soga, Kenichi; Liu, Ruoshui; Wassell, Ian J.

    2012-04-01

    In this paper, we study a design method for minimizing the total cost of a wireless sensor network (WSN) used for health monitoring of railway structures. First, we present the problem, that is to simultaneously determine the number of relays and their deployment locations, the transmission power level for each sensor and relay, and the routes for transferring sensor data to a gateway using multi-hop wireless communication. Second, we formulate this task as a mathematical programming problem, and to solve this problem, we propose a near optimal algorithm based on the Lagrangian heuristic method. Finally, we verify the effectiveness of our algorithm through computational experiments carried out using data acquired from a real WSN used for railway structural health monitoring.

  19. Application of the multi-scale finite element method to wave propagation problems in damaged structures

    NASA Astrophysics Data System (ADS)

    Casadei, F.; Ruzzene, M.

    2011-04-01

    This work illustrates the possibility to extend the field of application of the Multi-Scale Finite Element Method (MsFEM) to structural mechanics problems that involve localized geometrical discontinuities like cracks or notches. The main idea is to construct finite elements with an arbitrary number of edge nodes that describe the actual geometry of the damage with shape functions that are defined as local solutions of the differential operator of the specific problem according to the MsFEM approach. The small scale information are then brought to the large scale model through the coupling of the global system matrices that are assembled using classical finite element procedures. The efficiency of the method is demonstrated through selected numerical examples that constitute classical problems of great interest to the structural health monitoring community.

  20. Using hierarchically structured problem-solving knowledge in a rule-based process planning system

    SciTech Connect

    Hummel, K.E.; Brooks, S.L.

    1987-06-01

    A rule-based expert system, XCUT, currently is being developed which will generate process plans for the production of machined parts, given a feature-based part description. Due to the vast and dynamic nature of process planning knowledge, a technique has been used in the development of XCUT that segments problem solving knowledge into multiple rule bases. These rule bases are structured in a hierarchical manner that is reflective of the problem decomposition procedure used to generate a plan. An inference engine, HERB (Hierarchical Expert Rule Bases), has been developed which supports the manipulation of multiple rule bases during the planning process. This paper illustrates the hierarchical nature of problem-solving knowledge in the XCUT system and describes the use of HERB for programming with hierarchically structured rule bases. 6 refs., 21 figs.

  1. Developing Ill-Structured Problem-Solving Skills through Wilderness Education

    ERIC Educational Resources Information Center

    Collins, Rachel H.; Sibthorp, Jim; Gookin, John

    2016-01-01

    In a society that is becoming more dynamic, complex, and diverse, the ability to solve ill-structured problems (ISPs) has become an increasingly critical skill. Students who enter adult roles with the cognitive skills to address ISPs will be better able to assume roles in the emerging economies. Opportunities to develop and practice these skills…

  2. Epistemological Beliefs and Ill-Structured Problem-Solving in Solo and Paired Contexts

    ERIC Educational Resources Information Center

    Angeli, Charoula; Valanides, Nicos

    2012-01-01

    A mixed-method exploratory approach was employed to examine the relationship between epistemological beliefs and quality of thinking when participants first thought about an ill-structured problem alone, and then with another person in a dyad. The results showed that there was not a systematic connection between epistemological beliefs and…

  3. Structured Medication Review to Improve Pharmacotherapy in People with Intellectual Disability and Behavioural Problems

    ERIC Educational Resources Information Center

    Scheifes, Arlette; Egberts, Toine C. G.; Stolker, Joost Jan; Nijman, Henk. L. I.; Heerdink, Eibert R.

    2016-01-01

    Background: Polypharmacy and chronic drug use are common in people with intellectual disability and behavioural problems, although evidence of effectiveness and safety in this population is lacking. This study examined the effects of a structured medication review and aimed to improve pharmacotherapy in inpatients with intellectual disability.…

  4. Factor Structure, Internal Consistency, and Interrater Reliability of the Early Childhood Behavior Problem Screening Scale

    ERIC Educational Resources Information Center

    Nelson, Ron; Epstein, Michael; Griffith, Annette; Hopper, John

    2007-01-01

    The current study examined the initial psychometrics of the "Early Childhood Behavior Problem Screening Scale" (ECBPSS; Epstein & Nelson, 2006), namely the factor structure and associated internal consistency of factor items of parent and teacher versions as well as interrater reliability. Data came from samples of preschool- and kindergarten-age…

  5. Case Designs for Ill-Structured Problems: Analysis and Implications for Practice

    ERIC Educational Resources Information Center

    Dabbagh, Nada; Blijd, Cecily Williams

    2009-01-01

    This study is a third in a series of studies that examined students' information seeking and problem solving behaviors while interacting with one of two types of web-based representations of an ill-structured instructional design case: hierarchical (tree-like) and heterarchical (network-like). A Java program was used to track students' hypermedia…

  6. Solving the Problems of Iowa Food Deserts: Food Insecurity and Civic Structure

    ERIC Educational Resources Information Center

    Morton, Lois Wright; Bitto, Ella Annette; Oakland, Mary Jane; Sand, Mary

    2005-01-01

    Rural regions include places where food sources are not evenly distributed, leading to areas of concentration and food desert--places where few or no grocery stores exist. Individuals are hypothesized to depend on personal connections and the civic structure of where they live to help them solve the problem of food insecurity. We find that…

  7. The impact of general chemistry course structure on students' exam performance, attitudes and problem solving strategies

    NASA Astrophysics Data System (ADS)

    Caruthers, Heather Anne

    Analysis of the effect of course structure, including motivational tools, laboratory and how problem solving was presented in lecture on students' exam performance, attitudes toward the subject of chemistry, and problem solving strategy use. Exam performance indicates that the use of ressurection points on the final exam benefits students' learning, especially for the Middle Bottom quartile of students. Laboratory improves students' understanding when the exams correspond to laboratory content. Attitude differences, as measured by the Attitude toward the subject of chemistry inventory version 2, show some differences and the influence of the level of expertise in graduate student teaching assistants. The use of dimensional analysis to solve stoichiometry problems in lecture leads students to use that process to solve novel tasks in a similiar way, even if it is not efficient or effective. The students' familiarity with the content, as well as the problem solving process, influence how they solve tasks.

  8. Hybrid preconditioning for iterative diagonalization of ill-conditioned generalized eigenvalue problems in electronic structure calculations

    SciTech Connect

    Cai, Yunfeng; Bai, Zhaojun; Pask, John E.; Sukumar, N.

    2013-12-15

    The iterative diagonalization of a sequence of large ill-conditioned generalized eigenvalue problems is a computational bottleneck in quantum mechanical methods employing a nonorthogonal basis for ab initio electronic structure calculations. We propose a hybrid preconditioning scheme to effectively combine global and locally accelerated preconditioners for rapid iterative diagonalization of such eigenvalue problems. In partition-of-unity finite-element (PUFE) pseudopotential density-functional calculations, employing a nonorthogonal basis, we show that the hybrid preconditioned block steepest descent method is a cost-effective eigensolver, outperforming current state-of-the-art global preconditioning schemes, and comparably efficient for the ill-conditioned generalized eigenvalue problems produced by PUFE as the locally optimal block preconditioned conjugate-gradient method for the well-conditioned standard eigenvalue problems produced by planewave methods.

  9. A molecular picture of the problems in ensuring structural purity of tazofelone

    NASA Astrophysics Data System (ADS)

    Price, Louise S.; McMahon, Jennifer A.; Lingireddy, Sreenivas R.; Lau, Suk-Fai; Diseroad, Benjamin A.; Price, Sarah L.; Reutzel-Edens, Susan M.

    2014-12-01

    Almost twenty years after the crystal polymorphism of tazofelone was first studied at Lilly, the compound was revisited by calculating the crystal energy landscape and complementing the calculations with experimental work for calibration purposes. The crystal structure prediction study confirmed the stability of racemic form II (RCII) and showed that the racemic compound had greater potential for polymorphism than the single enantiomer. The seeding experiment that has previously been shown to produce a racemic solid solution (SS) correlates with the isostructurality between some low energy racemic structures and the enantiopure form. Other low energy structures have the same layer structure as both racemic polymorphs and the newly-discovered, but closely related, polymorph RCIII, which accounts for the difficulty in obtaining phase pure samples of the metastable RCI and RCIII and the problems of structural purity evidenced by streaked diffraction spots for RCI-III in the single crystal diffraction. This molecular picture of the problems in ensuring structural purity in the layer structure polymorphs of tazofelone not only explains the crystal dependent thermochemistry measurements of tazofelone, but also shows the value of combining a range of experimental and computational techniques to investigate the organic solid state.

  10. Gastropod diversification and community structuring processes in ancient Lake Ohrid: a metacommunity speciation perspective

    NASA Astrophysics Data System (ADS)

    Hauffe, T.; Albrecht, C.; Wilke, T.

    2015-09-01

    The Balkan Lake Ohrid is the oldest and most speciose freshwater lacustrine system in Europe. However, it remains unclear whether the diversification of its endemic taxa is mainly driven by neutral processes, environmental factors, or species interactions. This calls for a holistic perspective involving both evolutionary processes and ecological dynamics. Such a unifying framework - the metacommunity speciation model - considers how community assembly affects diversification and vice versa by assessing the relative contribution of the three main community assembly processes, dispersal limitation, environmental filtering, and species interaction. The current study therefore used the species-rich model taxon Gastropoda to assess how extant communities in Lake Ohrid are structured by performing process based metacommunity analyses. Specifically, the study aimed at (i) identifying the relative importance of the three community assembly processes and (ii) to test whether the importance of these individual processes changes gradually with lake depth or whether they are distinctively related to eco-zones. Based on specific simulation steps for each of the three processes, it could be demonstrated that dispersal limitation had the strongest influence on gastropod community structures in Lake Ohrid. However, it was not the exclusive assembly process but acted together with the other two processes - environmental filtering, and species interaction. In fact, the relative importance of the three community assembly processes varied both with lake depth and eco-zones, though the processes were better predicted by the latter. The study thus corroborated the high importance of dispersal limitation for both maintaining species richness in Lake Ohrid (through its impact on community structure) and generating endemic biodiversity (via its influence on diversification processes). However, according to the metacommunity speciation model, the inferred importance of environmental

  11. The mediating role of perceived peer support in the relation between quality of attachment and internalizing problems in adolescence: a longitudinal perspective.

    PubMed

    Pace, Ugo; Zappulla, Carla; Di Maggio, Rosanna

    2016-10-01

    The study was aimed to verify, from a longitudinal perspective, whether perceived peer support would mediate the relationship between attachment and internalizing problems. Longitudinal participants included 482 adolescents (245 boys) aged 14-15 years in Wave 1 and 17-18 years in Wave 2. Participants in Wave 1 completed the Relationship Questionnaire, and those in Wave 2 completed the Social Support Questionnaire and the Youth Self-Report. Results showed that secure attachment positively predicted high levels of perceived peer support and negatively predicted internalizing problems, whereas fearful and preoccupied attachment negatively predicted perceived peer support and positively predicted internalizing problems. The mediation models showed that perceived peer support partially mediated the relationship between secure attachment and internalizing problems as well as between preoccupied attachment and internalizing problems and between fearful attachment and internalizing problems. Our results confirm the role of subjective perception of peer support in contributing to the prediction of internalizing problems beyond attachment styles. PMID:27354278

  12. Geometric structure in seismic data, sampling and computational inverse problems (Invited)

    NASA Astrophysics Data System (ADS)

    De Hoop, M. V.; Andersson, F.; Tricoche, X.; Xia, J.; Yeh, R.

    2013-12-01

    In (nonlinear) seismic inverse problems one requires data from available large arrays acquired for many events. These data, naturally, contain information about Earth's interior over a large range of scales. From the viewpoint of detecting broadband wavefields, however, sampling often remains a challenge. We discuss various concepts and techniques which aid in analyzing and partitioning (or decomposing) such data, including compression with a novel, multi-scale, frame of Gaussian wavepackets, graph cuts and (extended) structure tensors. We emphasize the underlying geometric structure both in the physical embedding and in the associated space where the data find a natural representation. We consider several dimensionality reduction approaches including manifold learning, and develop possible notions of distance. These enable the development of methods of comparing data, for example, within and between arrays, and comparing observed with simulated data for inverse problems and regularization. Within the context of inverse problems we briefly mention the synthesis of the Dirichlet-to-Neumann map from the data, randomized sampling and direct structured solvers of the direct problem using hierarchically semi-separable (HSS) matrices in a multi-frequency formulation enabling an efficient workflow with a large number of events.

  13. Numerical Study of the Structure of Metastable Configurations for the Thomson Problem

    NASA Astrophysics Data System (ADS)

    Bondarenko, A. N.; Bugueva, T. V.; Kozinkin, L. A.

    2016-05-01

    A numerical method is proposed for solving the Thomson problem - finding stable positions for a system of N point charges distributed on a sphere that minimize the potential energy of the system. The behavior of this system is essentially nonlinear, and the number of metastable structures grows exponentially with N. This makes the problem of finding all stable configurations extremely difficult. The results of testing of the developed algorithm and of numerical study of the properties of the local potential energy minima for a system of point charges are presented.

  14. Analytical solution to a fracture problem in a tough layered structure

    NASA Astrophysics Data System (ADS)

    Hamamoto, Yukari; Okumura, Ko

    2008-08-01

    Nacre causes the shining beauty of pearl due to its remarkable layered structure, which is also strong. We reconsider a simplified layered model of nacre proposed previously [Okumura and de Gennes, Eur. Phys. J. E 4, 121 (2001)] and obtain an analytical solution to a fundamental crack problem. The result asserts that the fracture toughness is enhanced due to a large displacement around the crack tip (even if the crack-tip stress is not reduced). The derivation offers ideas for solving a number of boundary problems for partial differential equations important in many fields.

  15. Exploiting special problem structure when reliably investigating the solution of systems of IVPs and DDEs

    NASA Astrophysics Data System (ADS)

    Enright, W. H.

    2016-06-01

    In recent years we have developed a class of reliable order p methods for the approximate solution of general systems of initial value problems (IVPs) and delay differential equations (DDEs). In the theoretical analysis of these methods we have identified several trade-offs that do arise and have to be addressed when applying these methods to problems that exhibit special structure. Similar trade-offs also arise when one is concerned with investigating other important properties of the solutions. We will give examples of such trade-offs that arise when investigating the sensitivities of the solutions, and when very accurate approximate solutions are required.

  16. Elaborating the Structures of a Science Discipline to Improve Problem-Solving Instruction: An Account of Classical Genetics' Theory Structure, Function, and Development.

    ERIC Educational Resources Information Center

    Hafner, Robert; Culp, Sylvia

    1996-01-01

    Provides further details regarding a philosophical reconstruction of the structure of Classical Genetics Theory that can facilitate problem-solving instruction. Describes how that reconstruction can facilitate realistic problem solving on the part of students. Contains 60 references. (DDR)

  17. Single-parent family structure and sleep problems in black and white adolescents

    PubMed Central

    Troxel, Wendy M.; Lee, Laisze; Hall, Martica; Matthews, Karen A.

    2014-01-01

    Objectives Sleep is critical for adolescent health and is influenced by the family environment. In our study, we examined if family structure defined as single- vs 2-parent households affected adolescent sleep. Methods Participants were 242 (57% black; 47% boys) healthy adolescents (mean age, 15.7 years). Sleep was measured using self-report and wrist actigraphy over 7 consecutive nights. Outcomes were actigraphy-assessed sleep duration and sleep efficiency (SE) for the full week and weekends and weekdays separately, as well as self-reported sleep-wake problems and variability in bedtimes. Linear regression examined the relationship between family structure and sleep, after adjusting for age, sex, race, body mass index, and depressive symptoms, parental education, family conflict, and financial strain. Race and sex were examined as potential moderators. Results After adjusting for covariates, adolescents from single-parent households had poorer SE across the week and shorter sleep duration on weekends. White adolescents from 2-parent households had the fewer sleep-wake problems and lower bedtime variability, whereas black adolescents from single-parent households had the lowest weekend SE. There were no significant differences in family structure*sex interactions. Conclusion Our findings are the first to demonstrate that single-parent family structure is an independent correlate of sleep problems in adolescents, and they highlight the moderating role of race. PMID:24424100

  18. Investigating information-processing performance of different command team structures in the NATO Problem Space.

    PubMed

    Stanton, Neville A; Rothrock, Ling; Harvey, Catherine; Sorensen, Linda

    2015-01-01

    The structure of command teams is a significant factor on their communications and ability to process, and act upon, information. The NATO Problem Space was used in this study to represent three of the main dimensions in the battle-space environment: familiarity, rate of change, and strength of information position. Results show that the five common team structures (chain, Y, circle, wheel and all-connected) did not generally perform as predicted in team literature. Findings suggest that under dynamic and highly variable conditions, high levels of synchronisation and trust should be present. On the other hand, synchronisation and trust are less important in hierarchical, highly centralised structures, because team members are more willing to accept the authority of a single leader and this tight control ensures that these teams can perform well as long as the Problem Space is familiar, information is explicit and the environment does not change. Practitioner Summary: Some types of team structures are better suited to particular constraints of the battle-space than others. This research has shown that the much touted all-connected structure is often the worst performing structure and that the traditional hierarchy of command and control has much merit in the digital information age. PMID:25992491

  19. Parallel-vector computation for structural analysis and nonlinear unconstrained optimization problems

    NASA Technical Reports Server (NTRS)

    Nguyen, Duc T.

    1990-01-01

    Practical engineering application can often be formulated in the form of a constrained optimization problem. There are several solution algorithms for solving a constrained optimization problem. One approach is to convert a constrained problem into a series of unconstrained problems. Furthermore, unconstrained solution algorithms can be used as part of the constrained solution algorithms. Structural optimization is an iterative process where one starts with an initial design, a finite element structure analysis is then performed to calculate the response of the system (such as displacements, stresses, eigenvalues, etc.). Based upon the sensitivity information on the objective and constraint functions, an optimizer such as ADS or IDESIGN, can be used to find the new, improved design. For the structural analysis phase, the equation solver for the system of simultaneous, linear equations plays a key role since it is needed for either static, or eigenvalue, or dynamic analysis. For practical, large-scale structural analysis-synthesis applications, computational time can be excessively large. Thus, it is necessary to have a new structural analysis-synthesis code which employs new solution algorithms to exploit both parallel and vector capabilities offered by modern, high performance computers such as the Convex, Cray-2 and Cray-YMP computers. The objective of this research project is, therefore, to incorporate the latest development in the parallel-vector equation solver, PVSOLVE into the widely popular finite-element production code, such as the SAP-4. Furthermore, several nonlinear unconstrained optimization subroutines have also been developed and tested under a parallel computer environment. The unconstrained optimization subroutines are not only useful in their own right, but they can also be incorporated into a more popular constrained optimization code, such as ADS.

  20. Correlations among knowledge structures, force concept inventory, and problem-solving behaviors

    NASA Astrophysics Data System (ADS)

    Malone, Kathy L.

    2008-12-01

    The modeling instruction pedagogy for the teaching of physics has been proven to be quite effective at increasing the conceptual understanding and problem-solving abilities of students to a much greater extent than that of nonmodeling students. Little research has been conducted concerning the cognitive and metacognitive skills that modeling students develop that allow for these increases. Two studies were designed to answer the following question: In what ways do the knowledge structures, metacognitive skills, and problem-solving abilities differ between modeling and nonmodeling students? In study 1, the knowledge structures developed by two groups of high school physics students taught using differing pedagogies (modeling instruction in physics and traditional methods) were determined using a card-sort task. The student’s knowledge structures were then correlated with the scores they obtained on two measures: the force concept inventory (FCI) and a problem-solving task (PS task) developed for this study. The modeling students had a more expertlike knowledge structure, while the nonmodeling students produced structures that were novicelike. In addition, the expert score correlated highly with performance on both the FCI and PS task scores demonstrating that a higher expert score predicted a higher value on each of these measures while a higher surface feature score predicted a lower score on both of these measures. In study 2, a verbal protocol design allowed for a detailed study of the problem-solving and metacognitive skills utilized by the two groups. It was determined that the skills utilized by the modeling instruction students were more expertlike. In addition, the modeling students produced significantly fewer physics errors while catching and repairing a greater percentage of their errors.

  1. Multidimensional Riemann problem with self-similar internal structure. Part I - Application to hyperbolic conservation laws on structured meshes

    NASA Astrophysics Data System (ADS)

    Balsara, Dinshaw S.

    2014-11-01

    Multidimensional Riemann solvers have been formulated recently by the author (Balsara, 2010, 2012) [6,7]. They operate at the vertices of a two-dimensional mesh, taking input from all the neighboring states and yielding the resolved state and fluxes as output. The multidimensional Riemann problem produces a self-similar strongly interacting state which is the result of several one-dimensional Riemann problems interacting with each other. The prior work was restricted to the use of one-dimensional HLLC Riemann solvers as building blocks. In this paper, we formulate the problem in similarity variables. As a result, any self-similar one-dimensional Riemann solver can be used as a building block for the multidimensional Riemann solver. This paper focuses on the structure of the strongly-interacting state. (A video introduction to multidimensional Riemann solvers is available on http://www.nd.edu/~dbalsara/Numerical-PDE-Course.) In this work the strongly-interacting state is expanded in a set of basis functions that depend on the similarity variables. Consequently, the resolved state and the fluxes can be endowed with considerably richer sub-structure compared to prior work. Unlike the multidimensional HLLC Riemann solver, the need to independently specify a direction for the evolution of the contact discontinuity is eliminated. The richer sub-structure in the strongly-interacting state naturally accommodates waves that may be moving in any direction relative to the mesh, thereby minimizing mesh-imprinting. Two formulations are presented. The first formulation does not linearize the problem around a favorable state. Its derivation takes a few cues from the derivation of the multidimensional HLL Riemann solver. The second formulation identifies such a state and carries out a linearization of the fluxes about that state. This paper is the very first time that a series solution of the multidimensional Riemann problem has been presented. Explicit formulae are presented for

  2. Supporting Graduate Students of Color in Educational Administration Preparation Programs: Faculty Perspectives on Best Practices, Possibilities, and Problems

    ERIC Educational Resources Information Center

    Young, Michelle D.; Brooks, Jeffrey S.

    2008-01-01

    Overview: This article presents findings from a study that examined faculty perspectives on how individual faculty members and institutions support graduate students of color in educational administration preparation programs. Purpose: The purpose of this study was to identify strategies that faculty members and institutions employ to support…

  3. Parents’ Perceived Similarity to Their Children, and Parents’ Perspective Taking Efforts: Associations of Cross-Informant Discrepancies with Adolescent Problem Behavior

    PubMed Central

    Vierhaus, Marc; Rueth, Jana E.; Lohaus, Arnold

    2016-01-01

    The main goal of this study is to provide empirical evidence for a theoretical mechanism underlying cross-informant discrepancies (CID), which occur between reports of different informants (e.g., children/adolescents and parents) of children’s/adolescents’ problem behavior. Studies comprehensively corroborate the existence of CID. However, an explanation of CID is rudimentary and inconsistent. Respective research often suffers from methodological problems and is often atheoretical. Addressing these critics, this study uses polynomial regression and is based on research on mind perception and anchoring-and-adjustment theory. It was assumed that higher CID are associated with parents’ perceived similarity to their children, whereas lower CID are related to parents’ perspective-taking efforts. Analyses were based on N = 168 parent–child dyads (children’s mean age: 12.50 years). Reports on problem behavior displayed substantial mean differences and medium-sized correlations. Polynomial regressions on CID partly supported the influence of parents’ perceived similarity and perspective taking efforts on CID. Results are discussed in the context of a possible theoretical fundament for CID. PMID:27014169

  4. Teachers' Perspectives on Principal Mistreatment

    ERIC Educational Resources Information Center

    Blase, Joseph; Blase, Jo

    2006-01-01

    Although there is some important scholarly work on the problem of workplace mistreatment/abuse, theoretical or empirical work on abusive school principals is nonexistent. Symbolic interactionism was the theoretical structure for the present study. This perspective on social research is founded on three primary assumptions: (1) individuals act…

  5. The significance of the evanescent spectrum in structure-waveguide interaction problems.

    PubMed

    Tsouvalas, Apostolos; van Dalen, Karel N; Metrikine, Andrei V

    2015-10-01

    Modal decomposition is often applied in elastodynamics and acoustics for the solution of problems related to propagation of mechanical disturbances in waveguides. One of the key elements of this method is the solution of an eigenvalue problem for obtaining the roots of the dispersion equation, which signify the wavenumbers of the waves that may exist in the system. For non-dissipative media, the wavenumber spectrum consists of a finite number of real roots supplemented by infinitely many imaginary and complex ones. The former refer to the propagating modes in the medium, whereas the latter constitute the so-called evanescent spectrum. This study investigates the significance of the evanescent spectrum in structure-waveguide interaction problems. Two cases are analysed, namely, a beam in contact with a fluid layer and a cylindrical shell interacting with an acousto-elastic waveguide. The first case allows the introduction of a modal decomposition method and the establishment of appropriate criteria for the truncation of the modal expansions in a simple mathematical framework. The second case describes structure-borne wave radiation in an offshore environment during the installation of a pile with an impact hammer-a problem that has raised serious concerns in recent years due to the associated underwater noise pollution. PMID:26520340

  6. A tabu search approach for the NMR protein structure-based assignment problem.

    PubMed

    Cavuşlar, Gizem; Çatay, Bülent; Apaydın, Mehmet Serkan

    2012-01-01

    Spectroscopy is an experimental technique which exploits the magnetic properties of specific nuclei and enables the study of proteins in solution. The key bottleneck of NMR studies is to map the NMR peaks to corresponding nuclei, also known as the assignment problem. Structure-Based Assignment (SBA) is an approach to solve this computationally challenging problem by using prior information about the protein obtained from a homologous structure. NVR-BIP used the Nuclear Vector Replacement (NVR) framework to model SBA as a binary integer programming problem. In this paper, we prove that this problem is NP-hard and propose a tabu search (TS) algorithm (NVR-TS) equipped with a guided perturbation mechanism to efficiently solve it. NVR-TS uses a quadratic penalty relaxation of NVR-BIP where the violations in the Nuclear Overhauser Effect constraints are penalized in the objective function. Experimental results indicate that our algorithm finds the optimal solution on NVRBIP’s data set which consists of seven proteins with 25 templates (31 to 126 residues). Furthermore, it achieves relatively high assignment accuracies on two additional large proteins, MBP and EIN (348 and 243 residues, respectively), which NVR-BIP failed to solve. The executable and the input files are available for download at http://people.sabanciuniv.edu/catay/NVR-TS/NVR-TS.html. PMID:23221084

  7. Parents' conceptualization of adolescents' mental health problems: who adopts a psychiatric perspective and does it make a difference?

    PubMed

    Moses, Tally

    2011-02-01

    How parents give meaning to the problems of adolescents diagnosed with mental disorders and receiving treatment is likely related to important outcomes including parental well-being and commitment to treatment, as well as their own behaviors and reactions to their child. The aim of this cross-sectional, mixed-method study of 70 parents of adolescents receiving wraparound mental health services is to examine: (1) how parents conceptualize their child's MH problems; (2) factors related to parents' conceptualization of youths' problems using medical model terms; and (3) associations between parents' problem conceptualization and their emotional or coping responses to their child having psychiatric problem(s). Content analysis indicated that 54.3% of parents definitively conceptualized adolescents' problems using psychiatric terms, 37.1% reported uncertainty about the nature of their child's problems, and 8.6% gave alternative, non-psychiatric explanations for their child's problems. We found significant relationships between parents' problem conceptualization and their attitudes and experience with MH treatment, demographics, as well as with adolescents' clinical characteristics. Parents who conceptualized problems using psychiatric terminology were more likely to express sadness and pessimism relative to other parents, though there were no differences in expressions of worry, guilt, pragmatism and optimism by problem conceptualization. PMID:19847647

  8. Coulombic Interaction in Finnish Middle School Chemistry: A Systemic Perspective on Students' Conceptual Structure of Chemical Bonding

    ERIC Educational Resources Information Center

    Joki, Jarkko; Lavonen, Jari; Juuti, Kalle; Aksela, Maija

    2015-01-01

    The aim of this study was to design a novel and holistic way to teach chemical bonding at the middle school level according to research on the teaching and learning of bonding. A further aim was to investigate high achieving middle school students' conceptual structures concerning chemical bonding by using a systemic perspective. Students in one…

  9. Structural and Psychological Empowerment Climates, Performance, and the Moderating Role of Shared Felt Accountability: A Managerial Perspective

    ERIC Educational Resources Information Center

    Wallace, J. Craig; Johnson, Paul D.; Mathe, Kimberly; Paul, Jeff

    2011-01-01

    The authors proposed and tested a model in which data were collected from managers (n = 539) at 116 corporate-owned quick service restaurants to assess the structural and psychological empowerment process as moderated by shared-felt accountability on indices of performance from a managerial perspective. The authors found that empowering leadership…

  10. Experiences and Perspectives of Diverse Adolescent Youth Who Are Gifted: Navigating the Social and Organizational Structures of Public Schooling

    ERIC Educational Resources Information Center

    Baker, Jamie S.

    2012-01-01

    This qualitative case study explores the experiences and perspectives of seven diverse adolescent youth who are gifted as they navigate the social and organizational structures of public schooling as participants in gifted programming. Recent trends in education and the historical exploitations of giftedness that service the few, rather than the…

  11. Hybrid state vector methods for structural dynamic and aeroelastic boundary value problems

    NASA Technical Reports Server (NTRS)

    Lehman, L. L.

    1982-01-01

    A computational technique is developed that is suitable for performing preliminary design aeroelastic and structural dynamic analyses of large aspect ratio lifting surfaces. The method proves to be quite general and can be adapted to solving various two point boundary value problems. The solution method, which is applicable to both fixed and rotating wing configurations, is based upon a formulation of the structural equilibrium equations in terms of a hybrid state vector containing generalized force and displacement variables. A mixed variational formulation is presented that conveniently yields a useful form for these state vector differential equations. Solutions to these equations are obtained by employing an integrating matrix method. The application of an integrating matrix provides a discretization of the differential equations that only requires solutions of standard linear matrix systems. It is demonstrated that matrix partitioning can be used to reduce the order of the required solutions. Results are presented for several example problems in structural dynamics and aeroelasticity to verify the technique and to demonstrate its use. These problems examine various types of loading and boundary conditions and include aeroelastic analyses of lifting surfaces constructed from anisotropic composite materials.

  12. Application of Composite Structures in Bridge Engineering. Problems of Construction Process and Strength Analysis

    NASA Astrophysics Data System (ADS)

    Flaga, Kazimierz; Furtak, Kazimierz

    2015-03-01

    Steel-concrete composite structures have been used in bridge engineering from decades. This is due to rational utilisation of the strength properties of the two materials. At the same time, the reinforced concrete (or prestressed) deck slab is more favourable than the orthotropic steel plate used in steel bridges (higher mass, better vibration damping, longer life). The most commonly found in practice are composite girder bridges, particularly in highway bridges of small and medium spans, but the spans may reach over 200 m. In larger spans steel truss girders are applied. Bridge composite structures are also employed in cable-stayed bridge decks of the main girder spans of the order of 600, 800 m. The aim of the article is to present the cionstruction process and strength analysis problems concerning of this type of structures. Much attention is paid to the design and calculation of the shear connectors characteristic for the discussed objects. The authors focused mainly on the issues of single composite structures. The effect of assembly states on the stresses and strains in composite members are highlighted. A separate part of problems is devoted to the influence of rheological factors, i.e. concrete shrinkage and creep, as well as thermal factors on the stresses and strains and redistribution of internal forces.

  13. A Philosophical Perspective on the Relation between Cortical Midline Structures and the Self

    PubMed Central

    Musholt, Kristina

    2013-01-01

    In recent years there has been increasing evidence that an area in the brain called the cortical midline structures (CMSs) is implicated in what has been termed self-related processing. This article will discuss recent evidence for the relation between CMS and self-consciousness in light of several important philosophical distinctions. First, we should distinguish between being a self (i.e., being a subject of conscious experience) and being aware of being a self (i.e., being able to think about oneself as such). While the former consists in having a first-person perspective on the world, the latter requires the ability to explicitly represent one’s own perspective as such. Further, we should distinguish between being aware of oneself “as subject” and being aware of oneself “as object.” The focus of existing studies investigating the relation between CMS and self has been predominantly on the ability to think about oneself (and in particular thinking of oneself “as object”), while the more basic aspects involved in being a self have been neglected. However, it is important to widen the scope of the cognitive neuroscience to include the latter, not least because this might have important implications for a better understanding of disorders of the self, such as those involved in schizophrenia. In order to do so, cognitive neuroscience should work together with philosophy, including phenomenology. Second, we need to distinguish between personal and subpersonal level explanations. It will be argued that although it is important to respect this distinction, in principle, some subpersonal facts can enter into constitutive conditions of personal-level phenomena. However, in order for this to be possible, one needs both careful conceptual analysis and knowledge about relevant cognitive mechanisms. PMID:24032013

  14. Identifying the number of population clusters with structure: problems and solutions.

    PubMed

    Gilbert, Kimberly J

    2016-05-01

    The program structure has been used extensively to understand and visualize population genetic structure. It is one of the most commonly used clustering algorithms, cited over 11 500 times in Web of Science since its introduction in 2000. The method estimates ancestry proportions to assign individuals to clusters, and post hoc analyses of results may indicate the most likely number of clusters, or populations, on the landscape. However, as has been shown in this issue of Molecular Ecology Resources by Puechmaille (), when sampling is uneven across populations or across hierarchical levels of population structure, these post hoc analyses can be inaccurate and identify an incorrect number of population clusters. To solve this problem, Puechmaille () presents strategies for subsampling and new analysis methods that are robust to uneven sampling to improve inferences of the number of population clusters. PMID:27062588

  15. Analysis of random structure-acoustic interaction problems using coupled boundary element and finite element methods

    NASA Technical Reports Server (NTRS)

    Mei, Chuh; Pates, Carl S., III

    1994-01-01

    A coupled boundary element (BEM)-finite element (FEM) approach is presented to accurately model structure-acoustic interaction systems. The boundary element method is first applied to interior, two and three-dimensional acoustic domains with complex geometry configurations. Boundary element results are very accurate when compared with limited exact solutions. Structure-interaction problems are then analyzed with the coupled FEM-BEM method, where the finite element method models the structure and the boundary element method models the interior acoustic domain. The coupled analysis is compared with exact and experimental results for a simplistic model. Composite panels are analyzed and compared with isotropic results. The coupled method is then extended for random excitation. Random excitation results are compared with uncoupled results for isotropic and composite panels.

  16. You Need to Know: There Is a Causal Relationship between Structural Knowledge and Control Performance in Complex Problem Solving Tasks

    ERIC Educational Resources Information Center

    Goode, Natassia; Beckmann, Jens F.

    2010-01-01

    This study investigates the relationships between structural knowledge, control performance and fluid intelligence in a complex problem solving (CPS) task. 75 participants received either complete, partial or no information regarding the underlying structure of a complex problem solving task, and controlled the task to reach specific goals.…

  17. Algorithmic Perspectives of Network Transitive Reduction Problems and their Applications to Synthesis and Analysis of Biological Networks

    PubMed Central

    Aditya, Satabdi; DasGupta, Bhaskar; Karpinski, Marek

    2013-01-01

    In this survey paper, we will present a number of core algorithmic questions concerning several transitive reduction problems on network that have applications in network synthesis and analysis involving cellular processes. Our starting point will be the so-called minimum equivalent digraph problem, a classic computational problem in combinatorial algorithms. We will subsequently consider a few non-trivial extensions or generalizations of this problem motivated by applications in systems biology. We will then discuss the applications of these algorithmic methodologies in the context of three major biological research questions: synthesizing and simplifying signal transduction networks, analyzing disease networks, and measuring redundancy of biological networks. PMID:24833332

  18. Activity Structures and the Unfolding of Problem-Solving Actions in High-School Chemistry Classrooms

    NASA Astrophysics Data System (ADS)

    Criswell, Brett A.; Rushton, Greg T.

    2014-02-01

    In this paper, we argue for a more systematic approach for studying the relationship between classroom practices and scientific practices—an approach that will likely better support the systemic reforms being promoted in the Next Generation Science Standards in the USA and similar efforts in other countries. One component of that approach is looking at how the nature of the activity structure may influence the relative alignment between classroom and scientific practices. To that end, we build on previously published research related to the practices utilized by five high-school chemistry teachers as they enacted problem-solving activities in which students were likely to generate proposals that were not aligned with normative scientific understandings. In that prior work, our analysis had emphasized micro-level features of the talk interactions and how they related to the way students' ideas were explored; in the current paper, the analysis zooms out to consider the macro-level nature of the enactments associated with the activity structure of each lesson examined. Our data show that there were two general patterns to the activity structure across the 14 lessons scrutinized, and that each pattern had associated with it a constellation of features that impinged on the way the problem space was navigated. A key finding is that both activity structures (the expansive and the open) had features that aligned with scientific practices espoused in the Next Generation Science Standards—and both had features that were not aligned with those practices. We discuss the nature of these two structures, evidence of the relationship of each structure to key features of how the lessons unfolded, and the implications of these findings for both future research and the training of teachers.

  19. Semi-analytic approach for electromagnetic problems of large arrays structures

    NASA Astrophysics Data System (ADS)

    Rostami-Angas, Masoud

    helps us in finding the microscopic charactristics of the structure. Building on the theory that the molecules can be modeled by electric dipoles; a semi-analytic and semi-classical approach is developed to solve the electromagnetic problem of large array of dipoles and simulate the optical response of molecular aggregates. In chapter 3, a double negative (DNG) metamaterial structure is designed by unit cells of multilayer (concentric) spheres. The dispersion diagram is analyzed to find the frequency band with negative group velocity and the losses in DNG region. Basically, the combination of a positive permittivity dielectric and a negative permittivity plasmonic material can control the resonances of unit cells and therefore the effective permittivity of the 3-D structure. It is also discussed how a novel design of multilayer sphere unit cells leads to the DNG performance at the desired frequency band. In chapter 4, analytical solution to the problem of electromagnetic wave scattering by an arbitrary array of non-concentric spheres is derived. A full wave multipole expansion method is applied to express the electromagnetic fields in terms of the electric and magnetic dipole modes and the higher order moments. Vector spherical wave functions are used as the basis functions of the multipole expansions and the translation addition theorem is implemented to expand fields in desired coordinate systems. The accuracy and computational performance of the model are investigated and some interesting applications are discussed.

  20. Possibilities of the particle finite element method for fluid-soil-structure interaction problems

    NASA Astrophysics Data System (ADS)

    Oñate, Eugenio; Celigueta, Miguel Angel; Idelsohn, Sergio R.; Salazar, Fernando; Suárez, Benjamín

    2011-09-01

    We present some developments in the particle finite element method (PFEM) for analysis of complex coupled problems in mechanics involving fluid-soil-structure interaction (FSSI). The PFEM uses an updated Lagrangian description to model the motion of nodes (particles) in both the fluid and the solid domains (the later including soil/rock and structures). A mesh connects the particles (nodes) defining the discretized domain where the governing equations for each of the constituent materials are solved as in the standard FEM. The stabilization for dealing with an incompressibility continuum is introduced via the finite calculus method. An incremental iterative scheme for the solution of the non linear transient coupled FSSI problem is described. The procedure to model frictional contact conditions and material erosion at fluid-solid and solid-solid interfaces is described. We present several examples of application of the PFEM to solve FSSI problems such as the motion of rocks by water streams, the erosion of a river bed adjacent to a bridge foundation, the stability of breakwaters and constructions sea waves and the study of landslides.

  1. Towards high performance computing for molecular structure prediction using IBM Cell Broadband Engine - an implementation perspective

    PubMed Central

    2010-01-01

    Background RNA structure prediction problem is a computationally complex task, especially with pseudo-knots. The problem is well-studied in existing literature and predominantly uses highly coupled Dynamic Programming (DP) solutions. The problem scale and complexity become embarrassingly humungous to handle as sequence size increases. This makes the case for parallelization. Parallelization can be achieved by way of networked platforms (clusters, grids, etc) as well as using modern day multi-core chips. Methods In this paper, we exploit the parallelism capabilities of the IBM Cell Broadband Engine to parallelize an existing Dynamic Programming (DP) algorithm for RNA secondary structure prediction. We design three different implementation strategies that exploit the inherent data, code and/or hybrid parallelism, referred to as C-Par, D-Par and H-Par, and analyze their performances. Our approach attempts to introduce parallelism in critical sections of the algorithm. We ran our experiments on SONY Play Station 3 (PS3), which is based on the IBM Cell chip. Results Our results suggest that introducing parallelism in DP algorithm allows it to easily handle longer sequences which otherwise would consume a large amount of time in single core computers. The results further demonstrate the speed-up gain achieved in exploiting the inherent parallelism in the problem and also elicits the advantages of using multi-core platforms towards designing more sophisticated methodologies for handling a fairly long sequence of RNA. Conclusion The speed-up performance reported here is promising, especially when sequence length is long. To the best of our literature survey, the work reported in this paper is probably the first-of-its-kind to utilize the IBM Cell Broadband Engine (a heterogeneous multi-core chip) to implement a DP. The results also encourage using multi-core platforms towards designing more sophisticated methodologies for handling a fairly long sequence of RNA to predict

  2. Socio-Demographic and Practice-Oriented Factors Related to Proficiency in Problem Solving: A Lifelong Learning Perspective

    ERIC Educational Resources Information Center

    Desjardins, Richard; Ederer, Peer

    2015-01-01

    This article explores the relative importance of different socio-demographic and practice-oriented factors that are related to proficiency in problem solving in technology-rich environments (PSTREs) and by extension may be related to complex problem solving (CPS). The empirical analysis focuses on the proficiency measurements of PSTRE made…

  3. Co-morbidity Between Gambling Problems and Depressive Symptoms: A Longitudinal Perspective of Risk and Protective Factors.

    PubMed

    Dussault, Frédéric; Brendgen, Mara; Vitaro, Frank; Carbonneau, René; Boivin, Michel; Tremblay, Richard E

    2016-06-01

    In both adolescents and adults, gambling problems and depressive symptoms co-occur and share some common risk factors (e.g., impulsivity and socio-family risk). However, little is known about (1) the developmental course of the co-morbidity of these problems; (2) variables that may moderate the effect of these common risk factors on gambling problems and depressive symptoms. Of specific interest could be individuals' social relationships with significant others such as parents and friends, because research shows that they moderate the effect of other risk factors on gambling problems and depressive symptoms. The goals of this study were to: (a) identify developmental pathways for gambling problems and depressive symptoms, with a focus on co-morbidity; (b) assess the moderating effect of relationship quality with parents and friends on the link between common risk factors and the trajectories of gambling problems and depressive symptoms. Study participants were 878 males. Predictors were assessed during childhood and adolescence and gambling problems and depressive symptoms were assessed in late adolescence and young adulthood. Latent class analysis revealed four distinct joint trajectories of gambling problems and depressive symptoms. Subsequent logistic regression revealed that impulsivity predicted membership in all pathogenic trajectories, and quality of the relationship with parents predicted membership in depressogenic trajectories. In addition, we found that the membership in the comorbid trajectory can be predicted by an interaction between friendship quality and socio-family risk. PMID:25994287

  4. Predicting Change in Early Adolescent Problem Behavior in the Middle School Years: A Mesosystemic Perspective on Parenting and Peer Experiences

    ERIC Educational Resources Information Center

    Veronneau, Marie-Helene; Dishion, Thomas J.

    2010-01-01

    The transition into middle school may be a risky period in early adolescence. In particular, friendships, peer status, and parental monitoring during this developmental period can influence the development of problem behavior. This study examined interrelationships among peer and parenting factors that predict changes in problem behavior over the…

  5. Talking Physics during Small-Group Work with Context-Rich Problems--Analysed from an Ownership Perspective

    ERIC Educational Resources Information Center

    Enghag, Margareta; Gustafsson, Peter; Jonsson, Gunnar

    2009-01-01

    This study provides analyses of the conversations when university students work in small groups solving context-rich physics problems. We constructed context-rich, open-ended physics problems related to everyday life situations that lack some information required to solve and complete the tasks. The students' ownership of learning, their actions…

  6. Long-term management of AAR-affected structures - An international perspective

    SciTech Connect

    Charlwood, R.G.; Solymar, Z.V.

    1995-12-31

    The objective of the paper is to review international practice and comment on progress made in the long-term management of existing AAR-affected dams and hydroelectric plants. A updated detailed worldwide listing which now includes 104 AAR-affected structures constructed since 1900 will be presented. The listing gives summary data on the year of construction, the year that significant problems were noted, aggregate and cement types, measured expansion rates, test data, time to initial deterioration, duration of reaction, damage to the structures and effects on equipment, and repairs or replacement. A comprehensive bibliography will also be given. Analysis of the database and significant case histories will be used to identify issues affecting dam safety, plant operations, remedial measures and long-term performance of AAR-affected structures. The presentation will be illustrated by several case histories where remedial measures have been implemented.

  7. The Effectiveness of the Perfectly Matched Layer in Fluid-Structure Interaction Problems

    NASA Astrophysics Data System (ADS)

    Zhang, Lucy; Yang, Jubiao

    2015-11-01

    It is well recognized that spurious reflections on computational domain boundaries can have contamination of the flow field when solving fluid and/or wave equations. The effects are even more pronounced in fluid-structure interaction (FSI) problems, since the solid responses may be distorted due to the contaminated flow field. In this work, we implemented the perfectly matched layer (PML) technique and applied it in our fully-coupled immersed finite element method (IFEM), where Navier-Stokes equations are solved in the fluid domain with finite element method. With PML included as an absorbing layer it successfully absorbs outgoing waves from the interior of the computational domain and therefore keeps them from reflecting back from the computational boundary. Validation cases are shown to demonstrate the effectiveness of the PML in pure computational fluid dynamics cases, and then followed by FSI problems.

  8. Noncontradictory method of calculating radiation transfer, and problem of shock wave structure

    NASA Astrophysics Data System (ADS)

    Vyskrebentsev, A. I.; Nuzhnyy, V. A.; Rayzer, Y. P.

    1984-07-01

    Detail numerical calculations of equations of radiation transport and gas dynamics for a steady shock wave in air done by Zinn and Anderson have shown that for waves with amplitude near the critical point the iteration process does not converge to a final solution. This would seem to indicate that supercritical steady-state shock waves cannot exist. The problem of shock wave structure is analyzed with consideration of radiant heat exchange in the one-dimensinal steady state in a coordinate system fixed to the wavefront. The iteration procedure used in solving the problem eliminated the possibility of contradiction by matching the computational procedure with the factors that do not allow the temperature at any point in front of the shock to rise above the temperature behind the wavefront. The procedure yields temperature distribution in complete qualitative agreement with predictions of analytical theory, unambiguously demonstrating the fundamental possibility of existence of supercritical waves.

  9. Reliable use of determinants to solve nonlinear structural eigenvalue problems efficiently

    NASA Technical Reports Server (NTRS)

    Williams, F. W.; Kennedy, D.

    1988-01-01

    The analytical derivation, numerical implementation, and performance of a multiple-determinant parabolic interpolation method (MDPIM) for use in solving transcendental eigenvalue (critical buckling or undamped free vibration) problems in structural mechanics are presented. The overall bounding, eigenvalue-separation, qualified parabolic interpolation, accuracy-confirmation, and convergence-recovery stages of the MDPIM are described in detail, and the numbers of iterations required to solve sample plane-frame problems using the MDPIM are compared with those for a conventional bisection method and for the Newtonian method of Simpson (1984) in extensive tables. The MDPIM is shown to use 31 percent less computation time than bisection when accuracy of 0.0001 is required, but 62 percent less when accuracy of 10 to the -8th is required; the time savings over the Newtonian method are about 10 percent.

  10. SEMI-DEFINITE PROGRAMMING TECHNIQUES FOR STRUCTURED QUADRATIC INVERSE EIGENVALUE PROBLEMS

    PubMed Central

    LIN, MATTHEW M.; DONG, BO; CHU, MOODY T.

    2014-01-01

    In the past decade or so, semi-definite programming (SDP) has emerged as a powerful tool capable of handling a remarkably wide range of problems. This article describes an innovative application of SDP techniques to quadratic inverse eigenvalue problems (QIEPs). The notion of QIEPs is of fundamental importance because its ultimate goal of constructing or updating a vibration system from some observed or desirable dynamical behaviors while respecting some inherent feasibility constraints well suits many engineering applications. Thus far, however, QIEPs have remained challenging both theoretically and computationally due to the great variations of structural constraints that must be addressed. Of notable interest and significance are the uniformity and the simplicity in the SDP formulation that solves effectively many otherwise very difficult QIEPs. PMID:25392603

  11. Characterization of the Phase Space Structure of Circular Restricted Three-Body Problem: An Alternative Approach

    NASA Astrophysics Data System (ADS)

    Gupta, Beena R.; Kumar, Vinay

    In this paper, we have considered Time-Frequency Analysis (TFA) and Poincaré Surface of Section (PSS) for the study of the phase space structure of nonlinear dynamical system. We have examined a sample of orbits taken in the framework of Circular Restricted Three-Body Problem (CRTBP). We have computed ridge-plots (i.e. time-frequency landscape) using the phase of the continuous wavelet transform. Clear visualization of resonance trappings and the transitions is an important feature of this method, which is presented using ridge-plots. The identification between periodic and quasi-periodic, chaotic sticky and nonsticky and regular and chaotic orbits are done in comparatively less time and with less computational effort. The spatial case of Circular Restricted Three-Body problem is considered to show the strength of Time-Frequency Analysis to higher dimensional systems. Also, with the help of ridge-plots, we can visualize the phenomenon of transient chaos.

  12. Self-assembly and structural-functional flexibility of oxygenic photosynthetic machineries: personal perspectives.

    PubMed

    Garab, Győző

    2016-01-01

    This short review, with a bit of historical aspect and a strong personal bias and emphases on open questions, is focusing on the (macro-)organization and structural-functional flexibilities of the photosynthetic apparatus of oxygenic photosynthetic organisms at different levels of the structural complexity-selected problems that have attracted most my attention in the past years and decades. These include (i) the anisotropic organization of the pigment-protein complexes and photosynthetic membranes-a basic organizing principle of living matter, which can, and probably should be adopted to intelligent materials; (ii) the organization of protein complexes into chiral macrodomains, large self-assembling highly organized but structurally flexible entities with unique spectroscopic fingerprints-structures, where, important, high-level regulatory functions appear to 'reside'; (iii) a novel, dissipation-assisted mechanism of structural changes, based on a thermo-optic effect: ultrafast thermal transients in the close vicinity of dissipation of unused excitation energy, which is capable of inducing elementary structural changes; it makes plants capable of responding to excess excitation with reaction rates proportional to the overexcitation above the light-saturation of photosynthesis; (iv) the 3D ultrastructure of the granum-stroma thylakoid membrane assembly and other multilamellar membrane systems, and their remodelings-associated with regulatory mechanisms; (v) the molecular organization and structural-functional plasticity of the main light-harvesting complex of plants, in relation to their crystal structure and different in vivo and in vitro states; and (vi) the enigmatic role of non-bilayer lipids and lipid phases in the bilayer thylakoid membrane-warranting its high protein content and contributing to its structural flexibility. PMID:26494196

  13. A new evolutionary algorithm with structure mutation for the maximum balanced biclique problem.

    PubMed

    Yuan, Bo; Li, Bin; Chen, Huanhuan; Yao, Xin

    2015-05-01

    The maximum balanced biclique problem (MBBP), an NP-hard combinatorial optimization problem, has been attracting more attention in recent years. Existing node-deletion-based algorithms usually fail to find high-quality solutions due to their easy stagnation in local optima, especially when the scale of the problem grows large. In this paper, a new algorithm for the MBBP, evolutionary algorithm with structure mutation (EA/SM), is proposed. In the EA/SM framework, local search complemented with a repair-assisted restart process is adopted. A new mutation operator, SM, is proposed to enhance the exploration during the local search process. The SM can change the structure of solutions dynamically while keeping their size (fitness) and the feasibility unchanged. It implements a kind of large mutation in the structure space of MBBP to help the algorithm escape from local optima. An MBBP-specific local search operator is designed to improve the quality of solutions efficiently; besides, a new repair-assisted restart process is introduced, in which the Marchiori's heuristic repair is modified to repair every new solution reinitialized by an estimation of distribution algorithm (EDA)-like process. The proposed algorithm is evaluated on a large set of benchmark graphs with various scales and densities. Experimental results show that: 1) EA/SM produces significantly better results than the state-of-the-art heuristic algorithms; 2) it also outperforms a repair-based EDA and a repair-based genetic algorithm on all benchmark graphs; and 3) the advantages of EA/SM are mainly due to the introduction of the new SM operator and the new repair-assisted restart process. PMID:25137737

  14. First-passage problems: A probabilistic dynamic analysis for degraded structures

    NASA Technical Reports Server (NTRS)

    Shiao, Michael C.; Chamis, Christos C.

    1990-01-01

    Structures subjected to random excitations with uncertain system parameters degraded by surrounding environments (a random time history) are studied. Methods are developed to determine the statistics of dynamic responses, such as the time-varying mean, the standard deviation, the autocorrelation functions, and the joint probability density function of any response and its derivative. Moreover, the first-passage problems with deterministic and stationary/evolutionary random barriers are evaluated. The time-varying (joint) mean crossing rate and the probability density function of the first-passage time for various random barriers are derived.

  15. Control of large space structures: Status report on achievements and current problems

    NASA Technical Reports Server (NTRS)

    Lyons, M. G.; Aubrun, J. N.

    1983-01-01

    The objectives, state-of-the-art, and problems of large space structures control are outlined. The general objectives range from basic deployment and maneuvering, where some vibration modes may be suppressed, to disturbance rejection for very high performance imaging applications. The controls selected generally must produce some combination of eigenvalue/eigenvector and loads modification in order to achieve the mission objectives. An experiment illustrating the dynamic control of a suspended circular plate is described. Analysis methods used in system modelling, signal processing, and process control and monitoring are discussed. Sensor and actuator performance are assessed.

  16. Nuclear structure constrains on resonant energies: A solution of the cosmological 7Li problem?

    NASA Astrophysics Data System (ADS)

    Civitarese, O.; Mosquera, M. E.

    2013-01-01

    In this work, we study the cosmological 7Li problem from a nuclear structure point of view, by including resonances in the reactions which populate beryllium. The calculation of primordial abundances is performed by solving the balance equations semi-analytically. It is found that the primordial abundance of lithium is indeed reduced, as a consequence of the presence of resonant channels in the relevant cross sections. We set limits on the resonant energy for each reaction relevant for the chain leading to 7Li, by performing a statistical analysis of the available observational data.

  17. Analysis of factors affecting satisfaction level on problem based learning approach using structural equation modeling

    NASA Astrophysics Data System (ADS)

    Hussain, Nur Farahin Mee; Zahid, Zalina

    2014-12-01

    Nowadays, in the job market demand, graduates are expected not only to have higher performance in academic but they must also be excellent in soft skill. Problem-Based Learning (PBL) has a number of distinct advantages as a learning method as it can deliver graduates that will be highly prized by industry. This study attempts to determine the satisfaction level of engineering students on the PBL Approach and to evaluate their determinant factors. The Structural Equation Modeling (SEM) was used to investigate how the factors of Good Teaching Scale, Clear Goals, Student Assessment and Levels of Workload affected the student satisfaction towards PBL approach.

  18. Fractal structures for the Jacobi Hamiltonian of restricted three-body problem

    NASA Astrophysics Data System (ADS)

    Rollin, G.; Lages, J.; Shepelyansky, D. L.

    2016-08-01

    We study the dynamical chaos and integrable motion in the planar circular restricted three-body problem and determine the fractal dimension of the spiral strange repeller set of non-escaping orbits at different values of mass ratio of binary bodies and of Jacobi integral of motion. We find that the spiral fractal structure of the Poincaré section leads to a spiral density distribution of particles remaining in the system. We also show that the initial exponential drop of survival probability with time is followed by the algebraic decay related to the universal algebraic statistics of Poincaré recurrences in generic symplectic maps.

  19. Preferential flow in connected soil structures and the principle of "maximum energy dissipation": A thermodynamic perspective

    NASA Astrophysics Data System (ADS)

    Zehe, E.; Blume, T.; Bloeschl, G.

    2009-04-01

    "There is preferential flow at all scales"? This was a key message in a talk on ?Idle thoughts on a unifying theory of catchment hydrology? given by Bloeschl (2006). In this context ?preferential flow? was used to address rapid water flow along spatially connected flow paths of minimum flow resistance. Preferential flow seems in fact rather the rule than the exception. It occurs locally in non capillary macropores, at the hillslope scale in surface rills or through subsurface pipes. Rapid flow in connected biopores or sometimes shrinkage cracks is today accepted to play a key role for transport of agrochemicals in cohesive soils. The spatial distribution of worm burrows in the landscape may, furthermore, exert crucial control on rainfall runoff response and sediment yields at the hillslope and catchment scales. However, even if the population of connected biopores/macropores is known in soil we struggle in predicting onset, timing and strength of preferential flow events. Preferential flow is an intermittent, threshold phenomenon. Onset and intensity seems to be determined by the strength of the rainfall forcing and the wetness state of the soil. Furthermore, burrows of deep digging aenecic earthworms can ? even when being abandoned ? persist over decades as suggested by accumulation of clay particles or even radio nuclides. Thus, these structures ?survive? severe rainfall and subsurface flow events and still remain functional in the hydrological system. Why is it sometimes ?favourable? to take flow paths of minimum flow resistance and sometimes not? Why do these flow paths/ structures persist such a long time? Following Kleidon and Schimansky (2008) we suggest that a thermodynamic perspective ? looking at soil water flow as dissipative process in an open, non equilibrium thermodynamic system ? may help unrevealing these questions. However, we suggest a complementary perspective on soil water flow focusing rather on entropy production but on dissipation of

  20. The intentional stance as structure learning: a computational perspective on mindreading.

    PubMed

    Dindo, Haris; Donnarumma, Francesco; Chersi, Fabian; Pezzulo, Giovanni

    2015-10-01

    Recent theories of mindreading explain the recognition of action, intention, and belief of other agents in terms of generative architectures that model the causal relations between observables (e.g., observed movements) and their hidden causes (e.g., action goals and beliefs). Two kinds of probabilistic generative schemes have been proposed in cognitive science and robotics that link to a "theory theory" and "simulation theory" of mindreading, respectively. The former compares perceived actions to optimal plans derived from rationality principles and conceptual theories of others' minds. The latter reuses one's own internal (inverse and forward) models for action execution to perform a look-ahead mental simulation of perceived actions. Both theories, however, leave one question unanswered: how are the generative models - including task structure and parameters - learned in the first place? We start from Dennett's "intentional stance" proposal and characterize it within generative theories of action and intention recognition. We propose that humans use an intentional stance as a learning bias that sidesteps the (hard) structure learning problem and bootstraps the acquisition of generative models for others' actions. The intentional stance corresponds to a candidate structure in the generative scheme, which encodes a simplified belief-desire folk psychology and a hierarchical intention-to-action organization of behavior. This simple structure can be used as a proxy for the "true" generative structure of others' actions and intentions and is continuously grown and refined - via state and parameter learning - during interactions. In turn - as our computational simulations show - this can help solve mindreading problems and bootstrap the acquisition of useful causal models of both one's own and others' goal-directed actions. PMID:26168854

  1. Associations between Psychological Problems and Quality of Life in Pediatric Short Stature from Patients’ and Parents’ Perspectives

    PubMed Central

    Bullinger, Monika; Sommer, Rachel; Rohenkohl, Anja Christine; Bernardino Da Silva, Neuza Maria

    2016-01-01

    Short stature has been associated with psychosocial impairments, but whether treatments and achieved height impact on health-related quality of life (HrQoL) and psychological functioning of children/adolescents is still controversial. This study aimed to examine the effects of height deviation and treatment status on psychosocial adaptation outcomes and to identify clinical and psychosocial determinants of internalizing/externalizing problems in a large cohort of short statured children/adolescents from seven European countries. Participants were 345 children aged 8–18 years with a clinical diagnosis of short stature and 421 parents of 4–18 year-old patients. Children and parents reported on psychological problems (Strengths and Difficulties Questionnaire), generic (KIDSCREEN) and condition-specific HrQoL (QoLISSY). According to analyses of covariance, children/adolescents with current short stature presented more parent-reported internalizing problems and lower self- and parent-reported condition-specific HrQoL, compared to patients with an achieved height above -2SD. Treated children self-reported better HrQoL than the untreated group. Hierarchical regression analysis showed that, rather than height–related clinical variables, children’s sex, younger age and poorer HrQoL were the best predictors of psychological problems, explaining 39% of the variance in patient- and 42% in parent-reported internalizing problems, and 22% of the variance in patient- and 24% in parent-reported externalizing problems. Treatment status also moderated the negative links between patient-reported HrQoL and internalizing problems, explaining 2% of additional variance. These results suggest that children with current short stature are at greater risk for internalizing problems. Routine assessment of HrQoL in pediatric healthcare may help identify children for referral to specialized psychological assessment and intervention. PMID:27097033

  2. Associations between Psychological Problems and Quality of Life in Pediatric Short Stature from Patients' and Parents' Perspectives.

    PubMed

    Quitmann, Julia Hannah; Bullinger, Monika; Sommer, Rachel; Rohenkohl, Anja Christine; Bernardino Da Silva, Neuza Maria

    2016-01-01

    Short stature has been associated with psychosocial impairments, but whether treatments and achieved height impact on health-related quality of life (HrQoL) and psychological functioning of children/adolescents is still controversial. This study aimed to examine the effects of height deviation and treatment status on psychosocial adaptation outcomes and to identify clinical and psychosocial determinants of internalizing/externalizing problems in a large cohort of short statured children/adolescents from seven European countries. Participants were 345 children aged 8-18 years with a clinical diagnosis of short stature and 421 parents of 4-18 year-old patients. Children and parents reported on psychological problems (Strengths and Difficulties Questionnaire), generic (KIDSCREEN) and condition-specific HrQoL (QoLISSY). According to analyses of covariance, children/adolescents with current short stature presented more parent-reported internalizing problems and lower self- and parent-reported condition-specific HrQoL, compared to patients with an achieved height above -2SD. Treated children self-reported better HrQoL than the untreated group. Hierarchical regression analysis showed that, rather than height-related clinical variables, children's sex, younger age and poorer HrQoL were the best predictors of psychological problems, explaining 39% of the variance in patient- and 42% in parent-reported internalizing problems, and 22% of the variance in patient- and 24% in parent-reported externalizing problems. Treatment status also moderated the negative links between patient-reported HrQoL and internalizing problems, explaining 2% of additional variance. These results suggest that children with current short stature are at greater risk for internalizing problems. Routine assessment of HrQoL in pediatric healthcare may help identify children for referral to specialized psychological assessment and intervention. PMID:27097033

  3. The four ingredients of single-sequence RNA secondary structure prediction. A unifying perspective

    PubMed Central

    Rivas, Elena

    2013-01-01

    Any method for RNA secondary structure prediction is determined by four ingredients. The architecture is the choice of features implemented by the model (such as stacked basepairs, loop length distributions, etc.). The architecture determines the number of parameters in the model. The scoring scheme is the nature of those parameters (whether thermodynamic, probabilistic, or weights). The parameterization stands for the specific values assigned to the parameters. These three ingredients are referred to as “the model.” The fourth ingredient is the folding algorithms used to predict plausible secondary structures given the model and the sequence of a structural RNA. Here, I make several unifying observations drawn from looking at more than 40 years of methods for RNA secondary structure prediction in the light of this classification. As a final observation, there seems to be a performance ceiling that affects all methods with complex architectures, a ceiling that impacts all scoring schemes with remarkable similarity. This suggests that modeling RNA secondary structure by using intrinsic sequence-based plausible “foldability” will require the incorporation of other forms of information in order to constrain the folding space and to improve prediction accuracy. This could give an advantage to probabilistic scoring systems since a probabilistic framework is a natural platform to incorporate different sources of information into one single inference problem. PMID:23695796

  4. Modulation of Epigenetic Targets for Anticancer Therapy: Clinicopathological Relevance, Structural Data and Drug Discovery Perspectives

    PubMed Central

    Andreol, Federico; Barbosa, Arménio Jorge Moura; Daniele Parenti, Marco; Rio, Alberto Del

    2013-01-01

    Research on cancer epigenetics has flourished in the last decade. Nevertheless growing evidence point on the importance to understand the mechanisms by which epigenetic changes regulate the genesis and progression of cancer growth. Several epigenetic targets have been discovered and are currently under validation for new anticancer therapies. Drug discovery approaches aiming to target these epigenetic enzymes with small-molecules inhibitors have produced the first pre-clinical and clinical outcomes and many other compounds are now entering the pipeline as new candidate epidrugs. The most studied targets can be ascribed to histone deacetylases and DNA methyltransferases, although several other classes of enzymes are able to operate post-translational modifications to histone tails are also likely to represent new frontiers for therapeutic interventions. By acknowledging that the field of cancer epigenetics is evolving with an impressive rate of new findings, with this review we aim to provide a current overview of pre-clinical applications of small-molecules for cancer pathologies, combining them with the current knowledge of epigenetic targets in terms of available structural data and drug design perspectives. PMID:23016851

  5. Application of the SEA Directive to EU structural funds: Perspectives on effectiveness

    SciTech Connect

    Theophilou, Vassilia; Bond, Alan; Cashmore, Mat

    2010-02-15

    The European Union (EU) has two potentially conflicting policy goals: the Lisbon Agenda and the Cardiff process which, respectively, aim to make the EU most competitive and dynamic knowledge-based economy in the world, and integrate the environment into all EU policies. This research uses two case studies of Operational Programmes drawing on EU structural funds. Such programmes have recently been made subject to Strategic Environmental Assessment (SEA) under the EU SEA Directive, and allowed an assessment of the substantive (does it achieve its goals) and transactive (is it cost efficient) effectiveness of the SEA process, (i.e. does it support the Cardiff process or the Lisbon agenda?). Documentary review and interviews were the primary method drawing on actors involved both in the two case studies, and within the EU. The results indicate that transactive and substantive effectiveness are intrinsically linked and that both cases demonstrated some substantive effectiveness, but only one was transactively effective. Effectiveness was judged to be a function of design, procedure, substance as well as transaction, influenced by political issues. As with other research, we find that perspectives of effectiveness are very much driven by individual expectations, suggesting that a true measure of effectiveness might be the extent to which SEA can change expectations.

  6. Structuring policy problems for plastics, the environment and human health: reflections from the UK

    PubMed Central

    Shaxson, Louise

    2009-01-01

    How can we strengthen the science–policy interface for plastics, the environment and human health? In a complex policy area with multiple stakeholders, it is important to clarify the nature of the particular plastics-related issue before trying to understand how to reconcile the supply and demand for evidence in policy. This article proposes a simple problem typology to assess the fundamental characteristics of a policy issue and thus identify appropriate processes for science–policy interactions. This is illustrated with two case studies from one UK Government Department, showing how policy and science meet over the environmental problems of plastics waste in the marine environment and on land. A problem-structuring methodology helps us understand why some policy issues can be addressed through relatively linear flows of science from experts to policymakers but why others demand a more reflexive approach to brokering the knowledge between science and policy. Suggestions are given at the end of the article for practical actions that can be taken on both sides. PMID:19528061

  7. A practical solution in delineating thin conducting structures and suppression problem in direct current resistivity sounding

    NASA Astrophysics Data System (ADS)

    Sharma, Shashi Prakash; Biswas, Arkoprovo

    2013-08-01

    In hard rock areas, conventional apparent resistivity measurement using Schlumberger resistivity sounding fails to detect thin conducting structures (2-D and 3-D fractures filled with groundwater and mineral aggregate) concealed at a large depth. In the present study, an attempt is made to way-out the detection problem of deep seated thin conducting layer. It is proposed to study the apparent conductance simultaneously with resistivity sounding to detect such conductive zones qualitatively. Apparent conductance is defined as the magnitude of current flowing in the subsurface for a unit applied voltage through current electrodes. Even though such measurement is of qualitative importance, it gives extremely valuable information for the presence of conductive zones at depth in challenging hard rock terrain. It has been observed that apparent conductance increases significantly when groundwater bearing fractures and conductive bodies are encountered in the subsurface. Field data from different locations are presented to demonstrate the efficacy of such measurement. The measurement assists to the conventional resistivity sounding for successful prediction of groundwater zones at large depth in different hard rock areas and is of enormous importance. The approach is also used for possible solution of suppression problem in the DC resistivity sounding when intermediate layer is not reflected in the resistivity sounding curve. Finally, the approach can be used together with resistivity sounding to solve many practical problems.

  8. A memory structure adapted simulated annealing algorithm for a green vehicle routing problem.

    PubMed

    Küçükoğlu, İlker; Ene, Seval; Aksoy, Aslı; Öztürk, Nursel

    2015-03-01

    Currently, reduction of carbon dioxide (CO2) emissions and fuel consumption has become a critical environmental problem and has attracted the attention of both academia and the industrial sector. Government regulations and customer demands are making environmental responsibility an increasingly important factor in overall supply chain operations. Within these operations, transportation has the most hazardous effects on the environment, i.e., CO2 emissions, fuel consumption, noise and toxic effects on the ecosystem. This study aims to construct vehicle routes with time windows that minimize the total fuel consumption and CO2 emissions. The green vehicle routing problem with time windows (G-VRPTW) is formulated using a mixed integer linear programming model. A memory structure adapted simulated annealing (MSA-SA) meta-heuristic algorithm is constructed due to the high complexity of the proposed problem and long solution times for practical applications. The proposed models are integrated with a fuel consumption and CO2 emissions calculation algorithm that considers the vehicle technical specifications, vehicle load, and transportation distance in a green supply chain environment. The proposed models are validated using well-known instances with different numbers of customers. The computational results indicate that the MSA-SA heuristic is capable of obtaining good G-VRPTW solutions within a reasonable amount of time by providing reductions in fuel consumption and CO2 emissions. PMID:25056743

  9. Structuring policy problems for plastics, the environment and human health: reflections from the UK.

    PubMed

    Shaxson, Louise

    2009-07-27

    How can we strengthen the science-policy interface for plastics, the environment and human health? In a complex policy area with multiple stakeholders, it is important to clarify the nature of the particular plastics-related issue before trying to understand how to reconcile the supply and demand for evidence in policy. This article proposes a simple problem typology to assess the fundamental characteristics of a policy issue and thus identify appropriate processes for science-policy interactions. This is illustrated with two case studies from one UK Government Department, showing how policy and science meet over the environmental problems of plastics waste in the marine environment and on land. A problem-structuring methodology helps us understand why some policy issues can be addressed through relatively linear flows of science from experts to policymakers but why others demand a more reflexive approach to brokering the knowledge between science and policy. Suggestions are given at the end of the article for practical actions that can be taken on both sides. PMID:19528061

  10. Differential evolution: Global search problem in LEED-IV surface structural analysis

    SciTech Connect

    Nascimento, V.B.; Plummer, E.W.

    2015-02-15

    The search process associated with the quantitative theory–experiment comparison in Low Energy Electron Diffraction surface structural analysis can be very time consuming, especially in the case of complex materials with many atoms in the unit cell. Global search algorithms need to be employed to locate the global minimum of the reliability factor in the multi-dimensional structural parameter space. In this study we investigate the use of the Differential Evolution algorithm in Low Energy Electron Diffraction structural analysis. Despite the simplicity of its mechanism the Differential Evolution algorithm presents an impressive performance when applied to ultra-thin films of BaTiO{sub 3}(001) in a theory–theory comparison. A scaling relation of N{sup (1.47} {sup ±} {sup 0.08)} was obtained, where N is the total number of parameters to be optimized. - Highlights: • We investigated the use of the Differential Evolution algorithm (DE) for the LEED search problem. • The DE method was applied to the optimization of the surface structure of the BaTiO{sub 3}(001) ultra-thin films. • A very favorable scaling relation of N{sup 1.47} was obtained, where N is the total number of parameters to be optimized.

  11. Climate-Change Problem Solving: Structured Approaches Based on Real-World Experiences

    NASA Astrophysics Data System (ADS)

    Rood, R. B.; Briley, L. J.; Brown, D. A.

    2012-12-01

    Nearly two decades of experience using both seasonal and long-term climate model projections has led to the identification of a set of characteristics of the successful use of climate knowledge in planning and adaptation applications. These characteristics include end-to-end knowledge systems, co-generation or co-production of solution approaches by scientists and practitioners, and tailoring climate model information to the decision-making processes of the specific application. Glisaclimate.org strives to apply the growing body of research into the successful use of climate knowledge using a set of prototype, real-world applications. We describe an online problem-solving environment whose design is based on the characteristics of the successful use of climate predictions and projections by practitioners such as resource managers, urban planners, public health professionals, and policy makers. Design features of Glisaclimate.org include: Based on principles extracted from social science studies of the use of climate information. Anchored on structured templates of problem solving with the identification of common steps in problem solving that are repeated in one application to the next. Informed by interviews with real-world users who desire to incorporate climate-science knowledge into their decision making. Built with open-source tools to allow participation of a community of developers and to facilitate the sustainability of the effort. A structured approach to problem solving is described by four functions of information management. At the foundation of problem solving is the collection of existing information, an inventory stage. Following the collection of the information there are analysis and evaluation stages. In the analysis stage interfaces are described and knowledge gaps are identified. The evaluation stage assesses the quality of the information and the relevance of the information to the specific attributes of the problem. The development of plans

  12. Detection and characterization of usability problems in structured data entry interfaces in dentistry

    PubMed Central

    Walji, Muhammad F; Kalenderian, Elsbeth; Tran, Duong; Kookal, Krishna K; Nguyen, Vickie; Tokede, Oluwabunmi; White, Joel M; Vaderhobli, Ram; Ramoni, Rachel; Stark, Paul C; Kimmes, Nicole S.; Schoonheim-Klein, Meta E.; Patel, Vimla L

    2012-01-01

    Background Poor usability is one of the major barriers for optimally using electronic health records (EHRs). Dentists are increasingly adopting EHRs, and are using structured data entry interfaces to enter data such that the data can be easily retrieved and exchanged. Until recently, dentists have lacked a standardized terminology to consistently represent oral health diagnoses. Objectives In this study we evaluated the usability of a widely used EHR interface that allow the entry of diagnostic terms, using multi-faceted methods to identify problems and work with the vendor to correct them using an iterative design method. Methods Fieldwork was undertaken at two clinical sites, and dental students as subjects participated in user testing (n=32), interviews (n=36) and observations (n=24). Results User testing revealed that only 22–41% of users were able to successfully complete a simple task of entering one diagnosis, while no user was able to complete a more complex task. We identified and characterized 24 high-level usability problems reducing efficiency and causing user errors. Interface-related problems included unexpected approaches for displaying diagnosis, lack of visibility, and inconsistent use of UI widgets. Terminology related issues included missing and mis-categorized concepts. Work domain issues involved both absent and superfluous functions. In collaboration with the vendor, each usability problem was prioritized and a timeline set to resolve the concerns. Discussion Mixed methods evaluations identified a number of critical usability issues relating to the user interface, underlying terminology of the work domain. The usability challenges were found to prevent most users from successfully completing the tasks. Our further work we will determine if changes to the interface, terminology and work domain do result in improved usability. PMID:22749840

  13. A systematic review of qualitative research on the contributory factors leading to medicine-related problems from the perspectives of adult patients with cardiovascular diseases and diabetes mellitus

    PubMed Central

    Al Hamid, A; Ghaleb, M; Aljadhey, H; Aslanpour, Z

    2014-01-01

    Objectives To synthesise contributing factors leading to medicine-related problems (MRPs) in adult patients with cardiovascular diseases and/or diabetes mellitus from their perspectives. Design A systematic literature review of qualitative studies regarding the contributory factors leading to MRPs, medication errors and non-adherence, followed by a thematic synthesis of the studies. Data sources We screened Pubmed, EMBASE, ISI Web of Knowledge, PsycInfo, International Pharmaceutical Abstract and PsycExtra for qualitative studies (interviews, focus groups and questionnaires of a qualitative nature). Review methods Thematic synthesis was achieved by coding and developing themes from the findings of qualitative studies. Results The synthesis yielded 21 studies that satisfied the inclusion and exclusion criteria. Three themes emerged that involved contributing factors to MRPs: patient-related factors including socioeconomic factors (beliefs, feeling victimised, history of the condition, lack of finance, lack of motivation and low self-esteem) and lifestyle factors (diet, lack of exercise/time to see the doctor, obesity, smoking and stress), medicine-related factors (belief in natural remedies, fear of medicine, lack of belief in medicines, lack of knowledge, non-adherence and polypharmacy) and condition-related factors (lack of knowledge/understanding, fear of condition and its complications, and lack of control). Conclusions MRPs represent a major health threat, especially among adult patients with cardiovascular diseases and/or diabetes mellitus. The patients’ perspectives uncovered hidden factors that could cause and/or contribute to MRPs in these groups of patients. PMID:25239295

  14. Clinician and Parent Perspectives on Parent and Family Contextual Factors that Impact Community Mental Health Services for Children with Behavior Problems

    PubMed Central

    Jenkins, Melissa M.; Brookman-Frazee, Lauren

    2010-01-01

    The present study employed qualitative methods to examine multiple stakeholder perspectives regarding the role of parent and family contextual factors on community child mental health treatment for children with behavior problems. Findings suggest agreement between clinicians and parents on the number, types and importance of parent and family factors in children’s mental health services; however, stakeholders differed in reports of which factors were most salient. Specifically, clinicians endorsed most factors as being equally salient, while parents described a few salient factors, with parental stress and inadequate social support being the most frequently discussed. These qualitative data further elucidate the context of community services and have implications for evidence-based practice implementation and improving community care. PMID:21170419

  15. Structural geology practice and learning, from the perspective of cognitive science

    NASA Astrophysics Data System (ADS)

    Shipley, Thomas F.; Tikoff, Basil; Ormand, Carol; Manduca, Cathy

    2013-09-01

    Spatial ability is required by practitioners and students of structural geology and so, considering spatial skills in the context of cognitive science has the potential to improve structural geology teaching and practice. Spatial thinking skills may be organized using three dichotomies, which can be linked to structural geology practice. First, a distinction is made between separating (attending to part of a whole) and combining (linking together aspects of the whole). While everyone has a basic ability to separate and combine, experts attend to differences guided by experiences of rock properties in context. Second, a distinction is made between seeing the relations among multiple objects as separate items or the relations within a single object with multiple parts. Experts can flexibly consider relations among or between objects to optimally reason about different types of spatial problems. Third, a distinction is made between reasoning about stationary and moving objects. Experts recognize static configurations that encode a movement history, and create mental models of the processes that led to the static state. The observations and inferences made by a geologist leading a field trip are compared with the corresponding observations and inferences made by a cognitive psychologist interested in spatial learning. The presented framework provides a vocabulary for discussing spatial skills both within and between the fields of structural geology and cognitive psychology.

  16. Problem-Based Learning at the Receiving End: A "Mixed Methods" Study of Junior Medical Students' Perspectives

    ERIC Educational Resources Information Center

    Maudsley, Gillian; Williams, Evelyn M. I.; Taylor, David C. M.

    2008-01-01

    Qualitative insights about students' personal experience of inconsistencies in implementation of problem-based learning (PBL) might help refocus expert discourse about good practice. Aim: This study explored how junior medical students conceptualize: PBL; good tutoring; and less effective sessions. Methods: Participants comprised junior medical…

  17. Developing Resiliency in Students with Behavioural Problems in Hong Kong Secondary Schools: Teachers' Narratives from a School Guidance Perspective

    ERIC Educational Resources Information Center

    Hue, Ming-Tak

    2011-01-01

    Hong Kong schools are concerned about how students with behavioural problems could be supported. This article reports the findings of a study investigating teachers' constructs of students' resilience. Specifically it examines how it could be promoted through school guidance and factors affecting the development of students' resilient capability.…

  18. A Perspective Evaluation of Problem-Based Learning in ESL Classroom in the Malaysian Higher School Certificate Program

    ERIC Educational Resources Information Center

    Rashid, Radzuwan Ab.

    2011-01-01

    This study was initiated to explore how pre-university students who enrolled in the Malaysian Higher School Certificate program perceived their experiences in learning ESL through Problem-Based Learning (PBL). This small scale study involved 35 pre-university students in an upper sixth form in a secondary school in Kelantan, Malaysia. Participants…

  19. Interagency Collaboration in Vocational Rehabilitation for Persons with Mental Health Problems: The Perspective of the Service Users and the Professionals

    ERIC Educational Resources Information Center

    Germundsson, Per; Hillborg, Helene; Danermark, Berth

    2011-01-01

    There is an aspiration and policy within the European Union to fully involve persons with disabilities in the community; this implies an opportunity to gainful employment. A large percentage of disabled persons remain unemployed despite this policy, especially persons with mental health problems. This study aims at investigating how people with…

  20. Structure of ionic interfaces from an absolutely convergent solution of the Madelung problem

    SciTech Connect

    Wolf, D.

    1994-09-01

    The classic Madelung problem, i.e., the divergence associated with the r{sup -1} term in the Coulomb potential of condensed ionic systems, was cast into an absolutely convergent form that is readily evaluated by direct lattice summation, revealing a net r{sup -5} range of this potential. The realization that Coulomb interactions in condensed systems can actually be rather short ranged (if the system is overall neutral) permits novel physical insights into their structure and energetics to be gained. As an example, it was demonstrated that an understanding of the range and the nature of the convergence of the Coulomb potential leads naturally to the prediction, verified by computer simulations for rocksalt-structured surfaces, that all surfaces in predominantly ionic materials should be fundamentally reconstructed. The work also provides a conceptual framework for the theoretical treatment of polar surfaces and interfaces, as demonstrated for the case of the (111) stacking fault and of the (111) twin boundary in the rocksalt structure.

  1. Investigation of the problems with using gas adsorption to probe catalyst pore structure evolution during coking.

    PubMed

    Gopinathan, Navin; Greaves, Malcolm; Wood, Joseph; Rigby, Sean P

    2013-03-01

    A common approach to try to understand the mechanism of coking in heterogeneous catalysts is to monitor the evolution of the pore structure using gas adsorption analysis of discharged pellets. However, the standard methods of analysis of gas adsorption data, to obtain pore-size distributions, make the key assumption of thermodynamically-independent pores. This assumption neglects the possibility of co-operative adsorption phenomena, which will shown to be a critical problem when looking at coking catalysts. In this work the serial adsorption technique has been used to detect and assess the extent of co-operative effects in adsorption within coking catalysts. The reaction of decane over a hydroprocessing catalyst was used as a case study. It has been shown that the conventional analysis method would lead to a flawed picture of the pore structure changes during the coking process. For the case-study considered in this work, it was found that co-operative adsorption effects meant that 26% of the measured adsorption was occurring in pores up to three times larger than the size conventional analysis would presume. The serial adsorption technique was thus shown to provide important additional information on pore structure evolution during coking. A study of the kinetics of adsorption has been used to infer information about the general spatial location of the coking process within a pellet. PMID:23141698

  2. Parallel-vector computation for linear structural analysis and non-linear unconstrained optimization problems

    NASA Technical Reports Server (NTRS)

    Nguyen, D. T.; Al-Nasra, M.; Zhang, Y.; Baddourah, M. A.; Agarwal, T. K.; Storaasli, O. O.; Carmona, E. A.

    1991-01-01

    Several parallel-vector computational improvements to the unconstrained optimization procedure are described which speed up the structural analysis-synthesis process. A fast parallel-vector Choleski-based equation solver, pvsolve, is incorporated into the well-known SAP-4 general-purpose finite-element code. The new code, denoted PV-SAP, is tested for static structural analysis. Initial results on a four processor CRAY 2 show that using pvsolve reduces the equation solution time by a factor of 14-16 over the original SAP-4 code. In addition, parallel-vector procedures for the Golden Block Search technique and the BFGS method are developed and tested for nonlinear unconstrained optimization. A parallel version of an iterative solver and the pvsolve direct solver are incorporated into the BFGS method. Preliminary results on nonlinear unconstrained optimization test problems, using pvsolve in the analysis, show excellent parallel-vector performance indicating that these parallel-vector algorithms can be used in a new generation of finite-element based structural design/analysis-synthesis codes.

  3. Validation Study of a Method for Assessing Complex Ill-Structured Problem Solving by Using Causal Representations

    ERIC Educational Resources Information Center

    Eseryel, Deniz; Ifenthaler, Dirk; Ge, Xun

    2013-01-01

    The important but little understood problem that motivated this study was the lack of research on valid assessment methods to determine progress in higher-order learning in situations involving complex and ill-structured problems. Without a valid assessment method, little progress can occur in instructional design research with regard to designing…

  4. Design of a Dual-Mapping Learning Approach for Problem Solving and Knowledge Construction in Ill-Structured Domains

    ERIC Educational Resources Information Center

    Wu, Bian; Wang, Minhong; Spector, J. Michael; Yang, Stephen J. H.

    2013-01-01

    Problem solving has been increasingly used as an important approach to learning especially in ill-structured domains. It is assumed that knowledge can be better consolidated and extended through problem-solving experience. However, many learners do not have the ability to separate general knowledge from specific cases, which inhibits successful…

  5. The Male Role, Alcohol Use, and Alcohol Problems: A Structural Modeling Examination in Adult Women and Men.

    ERIC Educational Resources Information Center

    McCreary, Donald R.; Newcomb, Michael D.; Sadava, Stanley W.

    1999-01-01

    Utilizes structural model to examine relationships between three male-role variables, alcohol consumption, and alcohol-related problems in sample of men and women. For men, traditional attitudes led to more alcohol consumption, whereas agentic traits protected them from experiencing alcohol-related problems and from experiencing masculine…

  6. A Structured Approach to Teaching Applied Problem Solving through Technology Assessment.

    ERIC Educational Resources Information Center

    Fischbach, Fritz A.; Sell, Nancy J.

    1986-01-01

    Describes an approach to problem solving based on real-world problems. Discusses problem analysis and definitions, preparation of briefing documents, solution finding techniques (brainstorming and synectics), solution evaluation and judgment, and implementation. (JM)

  7. An Objective Structured Clinical Examination to Assess Problem-Based Learning

    PubMed Central

    O'Connell, Mary Beth; Garwood, Candice L.; Lehr, Victoria Tutag; Abdallah, Karina

    2012-01-01

    Objectives. To compare pharmacy students’ performance on an objective structured clinical examination (OSCE) to their performance on a written examination for the assessment of problem-based learning (PBL); and to determine students’ and faculty members’ perceptions of OSCEs for PBL evaluations. Design. Four OSCEs were added to the written examination to assess 4 PBL cases in a third-year pharmacotherapy course. OSCE scores were compared to written examination scores. Faculty members evaluated student performance. Assessment. OSCE performance did not correlate with the written-examination scores. Most students (≥ 75%) agreed that OSCEs reflected their learning from PBL and measured knowledge, communication, and clinical skills. A majority of faculty members (≥75%) agreed that OSCEs should be part of PBL assessment. Conclusions. Addition of an OSCE to written examinations was valued and provided a more comprehensive assessment of the PBL experience. PMID:22544961

  8. Method of adiabatic modes in studying problems of smoothly irregular open waveguide structures

    SciTech Connect

    Sevastianov, L. A.; Egorov, A. A.; Sevastyanov, A. L.

    2013-02-15

    Basic steps in developing an original method of adiabatic modes that makes it possible to solve the direct and inverse problems of simulating and designing three-dimensional multilayered smoothly irregular open waveguide structures are described. A new element in the method is that an approximate solution of Maxwell's equations is made to obey 'inclined' boundary conditions at the interfaces between themedia being considered. These boundary conditions take into account the obliqueness of planes tangent to nonplanar boundaries between the media and lead to new equations for coupled vector quasiwaveguide hybrid adiabatic modes. Solutions of these equations describe the phenomenon of 'entanglement' of two linear polarizations of an irregular multilayered waveguide, the appearance of a new mode in an entangled state, and the effect of rotation of the polarization plane of quasiwaveguide modes. The efficiency of the method is demonstrated by considering the example of numerically simulating a thin-film generalized waveguide Lueneburg lens.

  9. Graph theory approach to the eigenvalue problem of large space structures

    NASA Technical Reports Server (NTRS)

    Reddy, A. S. S. R.; Bainum, P. M.

    1981-01-01

    Graph theory is used to obtain numerical solutions to eigenvalue problems of large space structures (LSS) characterized by a state vector of large dimensions. The LSS are considered as large, flexible systems requiring both orientation and surface shape control. Graphic interpretation of the determinant of a matrix is employed to reduce a higher dimensional matrix into combinations of smaller dimensional sub-matrices. The reduction is implemented by means of a Boolean equivalent of the original matrices formulated to obtain smaller dimensional equivalents of the original numerical matrix. Computation time becomes less and more accurate solutions are possible. An example is provided in the form of a free-free square plate. Linearized system equations and numerical values of a stiffness matrix are presented, featuring a state vector with 16 components.

  10. ALPS: The Age-Layered Population Structure for Reducing the Problem of Premature Convergence

    NASA Technical Reports Server (NTRS)

    Hornby, Gregory S.

    2006-01-01

    To reduce the problem of premature convergence we define a new attribute of an individual, its age, and propose the Age-Layered Population Structure (ALPS), in which age is used to restrict competition and breeding between members of the population. ALPS differs from a typical EA by segregating individuals into different age-layers by their age - a measure of how long the genetic material has been in the population - and by regularly replacing all individuals in the bottom layer with randomly generated ones. The introduction of new, randomly generated individuals at regular intervals results in an EA that is never completely converged and is always looking at new parts of the fitness landscape. By using age to restrict competition and breeding search is able to develop promising young individuals without them being dominated by older ones. We demonstrate the effectiveness of the ALPS algorithm on an antenna design problem in which evolution with ALPS produces antennas more than twice as good as does evolution with two other types of EAs. Further analysis shows that the ALPS model does allow the offspring of newly generated individuals to move the population out of mediocre local-optima to better parts of the fitness landscape.

  11. A nonlocal structure tensor-based approach for multicomponent image recovery problems.

    PubMed

    Chierchia, Giovanni; Pustelnik, Nelly; Pesquet-Popescu, Béatrice; Pesquet, Jean-Christophe

    2014-12-01

    Nonlocal total variation (NLTV) has emerged as a useful tool in variational methods for image recovery problems. In this paper, we extend the NLTV-based regularization to multicomponent images by taking advantage of the structure tensor (ST) resulting from the gradient of a multicomponent image. The proposed approach allows us to penalize the nonlocal variations, jointly for the different components, through various l(1, p)-matrix-norms with p ≥ 1. To facilitate the choice of the hyperparameters, we adopt a constrained convex optimization approach in which we minimize the data fidelity term subject to a constraint involving the ST-NLTV regularization. The resulting convex optimization problem is solved with a novel epigraphical projection method. This formulation can be efficiently implemented because of the flexibility offered by recent primal-dual proximal algorithms. Experiments are carried out for color, multispectral, and hyperspectral images. The results demonstrate the interest of introducing a nonlocal ST regularization and show that the proposed approach leads to significant improvements in terms of convergence speed over current state-of-the-art methods, such as the alternating direction method of multipliers. PMID:25347882

  12. Lagrangian coherent structures in the planar elliptic restricted three-body problem

    NASA Astrophysics Data System (ADS)

    Gawlik, Evan S.; Marsden, Jerrold E.; Du Toit, Philip C.; Campagnola, Stefano

    2009-03-01

    This study investigates Lagrangian coherent structures (LCS) in the planar elliptic restricted three-body problem (ER3BP), a generalization of the circular restricted three-body problem (CR3BP) that asks for the motion of a test particle in the presence of two elliptically orbiting point masses. Previous studies demonstrate that an understanding of transport phenomena in the CR3BP, an autonomous dynamical system (when viewed in a rotating frame), can be obtained through analysis of the stable and unstable manifolds of certain periodic solutions to the CR3BP equations of motion. These invariant manifolds form cylindrical tubes within surfaces of constant energy that act as separatrices between orbits with qualitatively different behaviors. The computation of LCS, a technique typically applied to fluid flows to identify transport barriers in the domains of time-dependent velocity fields, provides a convenient means of determining the time-dependent analogues of these invariant manifolds for the ER3BP, whose equations of motion contain an explicit dependency on the independent variable. As a direct application, this study uncovers the contribution of the planet Mercury to the Interplanetary Transport Network, a network of tubes through the solar system that can be exploited for the construction of low-fuel spacecraft mission trajectories.

  13. Early problem behavior among children from low-income, mother-headed families: a multiple risk perspective.

    PubMed

    Olson, Sheryl L; Ceballo, Rosario; Park, Curie

    2002-12-01

    Examined proximal and contextual factors most strongly related to externalizing behavior among young children growing up in low-income, mother-headed families. Participants were 50 low-income single mothers and their preschool-age children who were visited twice in the home setting. Measures of proximal (low levels of supportive parenting, high levels of punitive disciplinary practices, low levels of maternal emotional well-being) and contextual (low maternal support, high levels of family stress) risk were assessed in relation to maternal reports of child externalizing behavior and an index of negative child behavior during a clean-up task. Child defiance during the clean-up task was highly associated with punitive maternal control in the same situation but had no other direct correlates. However, multiple risk factors representing both proximal and contextual variables were associated with variations in children's behavior problem scores. Mothers of children with high behavior problem scores reported lower feelings of self-efficacy in handling child care and emotional stressors, more frequent use of punitive child disciplinary practices, and lower feelings of satisfaction with the quality of their supportive resources than others. Maternal self-evaluations of coping efficacy mediated the relation between perceived support and child behavior problems, suggesting that constructs of personal control are important to represent in future studies of highly stressed parents. PMID:12402562

  14. The soil-like substrate: problems and perspective of its use for higher plants cultivation in LSS

    NASA Astrophysics Data System (ADS)

    Tikhomirov, Alexander A.; Velichko, Vladimir; Nickolay Manukovsky, D..; Ushakova, Sofya; Kovalev, Vladimir

    Being the product of biological mineralization of plant wastes, the soil-like substrate (SLS) contains sufficient amount of nutrients required for plant growth and development. The multiple experiments carried out at the IBP SB RAS demonstrated the SLS fitness for cultivation of higher plant of phototrophic unit in biological-technical life support systems (BTLSS). Together with it, some problems demanding further investigations and solutions had revealed. One of the cardinal problems was interlinked with a relatively low allowance of assimilable nitrogen in comparison with other elements contained in the SLS. Different problems arising under a durational plant cultivation on the SLS in a regime of multi-species uneven-aged conveyer is considered. The work attends considerable attention to analysis of questions occurring at plant cultivation on a reusable SLS that resulted in a yield decrease. The ways of more effective exploitation of the SLS both as a bioreactor for plant wastes mineralization and as a substrate for plant cultivation in a long-functioning BTLSS of an increased closure level of mass exchange processes are suggested.

  15. Tackling pseudosymmetry problems in electron backscatter diffraction (EBSD) analyses of perovskite structures

    NASA Astrophysics Data System (ADS)

    Mariani, Elisabetta; Kaercher, Pamela; Mecklenburgh, Julian; Wheeler, John

    2016-04-01

    Perovskite minerals form an important mineral group that has applications in Earth science and emerging alternative energy technologies, however crystallographic quantification of these minerals with electron backscatter diffraction (EBSD) is not accurate due to pseudosymmetry problems. The silicate perovskite Bridgmanite, (Mg,Fe)SiO3, is understood to be the dominant phase in the Earth's lower mantle. Gaining insight into its physical and rheological properties is therefore vital to understand the dynamics of the Earth's deep interior. Rock deformation experiments on analogue perovskite phases, for example (Ca,Sr)TiO3, combined with quantitative microstructural analyses of the recovered samples by EBSD, yield datasets that can reveal what deformation mechanisms may dominate the flow of perovskite in the lower mantle. Additionally, perovskite structures have important technological applications as new, suitable cathodes for the operation of more efficient and environmentally-friendly solid oxide fuel cells (SOFC). In recent years they have also been recognised as a potential substitute for silicon in the next generation of photovoltaic cells for the construction of economic and energy efficient solar panels. EBSD has the potential to be a valuable tool for the study of crystal orientations achieved in perovskite substrates as crystal alignment has a direct control on the properties of these materials. However, perovskite structures currently present us with challenges during the automated indexing of Kikuchi bands in electron backscatter diffraction patterns (EBSPs). Such challenges are represented by the pseudosymmetric character of perovskites, where atoms are subtly displaced (0.005 nm to 0.05 nm) from their higher symmetry positions. In orthorhombic Pbnm perovskites, for example, pseudosymmetry may be evaluated from the c/a unit cell parameter ratio, which is very close to 1. Two main types of distortions from the higher symmetry structure are recognised: a

  16. Effects of structural and dynamic family characteristics on the development of depressive and aggressive problems during adolescence. The TRAILS study.

    PubMed

    Sijtsema, J J; Oldehinkel, A J; Veenstra, R; Verhulst, F C; Ormel, J

    2014-06-01

    Both structural (i.e., SES, familial psychopathology, family composition) and dynamic (i.e., parental warmth and rejection) family characteristics have been associated with aggressive and depressive problem development. However, it is unclear to what extent (changes in) dynamic family characteristics have an independent effect on problem development while accounting for stable family characteristics and comorbid problem development. This issue was addressed by studying problem development in a large community sample (N = 2,230; age 10-20) of adolescents using Linear Mixed models. Paternal and maternal warmth and rejection were assessed via the Egna Minnen Beträffande Uppfostran for Children (EMBU-C). Aggressive and depressive problems were assessed via subscales of the Youth/Adult Self-Report. Results showed that dynamic family characteristics independently affected the development of aggressive problems. Moreover, maternal rejection in preadolescence and increases in paternal rejection were associated with aggressive problems, whereas decreases in maternal rejection were associated with decreases in depressive problems over time. Paternal and maternal warmth in preadolescence was associated with fewer depressive problems during adolescence. Moreover, increases in paternal warmth were associated with fewer depressive problems over time. Aggressive problems were a stable predictor of depressive problems over time. Finally, those who increased in depressive problems became more aggressive during adolescence, whereas those who decreased in depressive problems became also less aggressive. Besides the effect of comorbid problems, problem development is to a large extent due to dynamic family characteristics, and in particular to changes in parental rejection, which leaves much room for parenting-based interventions. PMID:24043499

  17. Existence of a weak solution to a fluid-elastic structure interaction problem with the Navier slip boundary condition

    NASA Astrophysics Data System (ADS)

    Muha, Boris; Čanić, Sunčica

    2016-06-01

    We study a nonlinear, moving boundary fluid-structure interaction (FSI) problem between an incompressible, viscous Newtonian fluid, modeled by the 2D Navier-Stokes equations, and an elastic structure modeled by the shell or plate equations. The fluid and structure are coupled via the Navier slip boundary condition and balance of contact forces at the fluid-structure interface. The slip boundary condition might be more realistic than the classical no-slip boundary condition in situations, e.g., when the structure is "rough", and in modeling FSI dynamics near, or at a contact. Cardiovascular tissue and cell-seeded tissue constructs, which consist of grooves in tissue scaffolds that are lined with cells, are examples of "rough" elastic interfaces interacting with an incompressible, viscous fluid. The problem of heart valve closure is an example of a FSI problem with a contact involving elastic interfaces. We prove the existence of a weak solution to this class of problems by designing a constructive proof based on the time discretization via operator splitting. This is the first existence result for fluid-structure interaction problems involving elastic structures satisfying the Navier slip boundary condition.

  18. On Index Structures in Hybrid Metaheuristics for Routing Problems with Hard Feasibility Checks: An Application to the 2-Dimensional Loading Vehicle Routing Problem

    NASA Astrophysics Data System (ADS)

    Strodl, Johannes; Doerner, Karl F.; Tricoire, Fabien; Hartl, Richard F.

    In this paper we study the impact of different index structures used within hybrid solution approaches for vehicle routing problems with hard feasibility checks. We examine the case of the vehicle routing problem with two-dimensional loading constraints, which combines the loading of freight into the vehicles and the routing of the vehicles to satisfy the demands of the customers. The problem is solved by a variable neighborhood search for the routing part, in which we embed an exact procedure for the loading subproblem. The contribution of the paper is threefold: i) Four different index mechanisms for managing the subproblems are implemented and tested. It is shown that simple index structures tend to lead to better solutions than more powerful albeit complex ones, when using the same runtime limits. ii) The problem of balancing the CPU budget between exploration of different solutions and exact solution of the loading subproblem is investigated; experiments show that solving exactly hard subproblems can lead to better solution quality over the whole solution process. iii) New best results are presented on existing benchmark instances.

  19. Platelet-rich plasma therapy for knee joint problems: review of the literature, current practice and legal perspectives in Korea.

    PubMed

    Park, Yong-Geun; Han, Seung Beom; Song, Sang Jun; Kim, Tae Jin; Ha, Chul-Won

    2012-06-01

    Platelet-rich plasma (PRP) is a concentrate extract of platelets from autologous blood, and represents a possible treatment option for the stimulation and acceleration of soft-tissue healing and regeneration in orthopedics. Currently, the availability of devices for outpatient preparation and delivery contributes to the increase in the clinical use of PRP therapy in practical setting of orthopedic fields. However, there is still paucity of scientific evidence in the literature to prove efficacy of PRP therapy for the treatment of ligament or tendon problems around the knee joint. Moreover, strong evidence from well-designed clinical trials to support the PRP therapy for osteoarthritis of the knee joint is yet scanty in the literature. Scientific studies need to be performed to assess clinical indications, efficacy, and safety of PRP, and this will require high powered randomized controlled trials. Nonetheless, some hospitals exaggeratedly advertise PRP procedures as the ultimate treatment and a novel technology with abundant scientific evidence for the treatment of knee problems. As a matter of fact, PRP protocols are currently approved only for use in clinical trials and research, and are not allowed for treatment purpose by any institutions in Korea. At present, clinical use of PRP therapy for ligament or tendon problems or osteoarthritis of knee joint is defined as illegal medical practice, regardless of whether it is performed as a sole procedure or as a part of prolotherapy, because the safety and validity are not yet approved by the Ministry of Health and Welfare and Health Insurance Review and Assessment Service. Practicing physicians should remember that injection of PRP to patients by imposing medical charge is still illegal as per the current medical law in Korea. PMID:22708106

  20. [Gender identity disorder and related sexual behavior problems in children and adolescents: from the perspective of development and child psychiatry].

    PubMed

    Yamashita, Hiroshi

    2013-01-01

    exaggerates to gender-related problems. However, these views do not explain all cases; true comorbidity of ASD and GID should be considered. A full assessment including evaluation of the family, school, and social environment is essential as other emotional and behavioral problems are very common and unresolved issues in the child's environment are often present e. g., loss. Separation problems are particularly common in the younger group. Intervention should aim to assist development, particularly that of gender identity. It should focus on ameliorating the comorbid problems and difficulties in the child's life and reducing the distress experienced by the child. PMID:23691817

  1. Structural antioxidant defense mechanisms in the mammalian and nonmammalian kidney: different solutions to the same problem?

    PubMed

    O'Connor, Paul M; Evans, Roger G

    2010-09-01

    Tissue oxygen levels are tightly regulated in all organs. This poses a challenge for the kidney, as its function requires blood flow, and thus, oxygen delivery to greatly exceed its metabolic requirements. Because superoxide production in the kidney is dependent on oxygen availability, tissue hyperoxia could drive oxidative stress. In the mammalian renal cortex, this problem may have been solved, in part, through a structural antioxidant defense mechanism. That is, arteries and veins are closely associated in a countercurrent arrangement, facilitating diffusional arterial-to-venous (AV) oxygen shunting. Because of this mechanism, a proportion of the oxygen delivered in the renal artery never reaches kidney tissue but instead diffuses to the closely associated renal veins, thus limiting oxygen transport to tissue. In the nonmammalian kidney, arteries and veins are not arranged in an intimate countercurrent fashion as in mammals; thus AV oxygen shunting is likely less important in regulation of kidney oxygenation in these species. Instead, the kidney's blood supply is predominately of venous origin. This likely has a similar impact on tissue oxygenation as AV oxygen shunting, of limiting delivery of oxygen to renal tissue. Thus, we hypothesize the evolution of structural antioxidant mechanisms that are anatomically divergent but functionally homologous in the mammalian and nonmammalian kidney. PMID:20660108

  2. Designing a Beryllium-Free Deep-Ultraviolet Nonlinear Optical Material without a Structural Instability Problem.

    PubMed

    Zhao, Sangen; Kang, Lei; Shen, Yaoguo; Wang, Xiaodong; Asghar, Muhammad Adnan; Lin, Zheshuai; Xu, Yingying; Zeng, Siyuan; Hong, Maochun; Luo, Junhua

    2016-03-01

    A beryllium-free deep-ultraviolet (deep-UV) nonlinear optical (NLO) material K3Ba3Li2Al4B6O20F is developed mainly by the element substitution of Be for Al and Li from Sr2Be2B2O7 that was considered as one of the most promising deep-UV NLO materials. K3Ba3Li2Al4B6O20F preserves the structural merits of Sr2Be2B2O7 and thus exhibits no layering growth tendency and possesses the optical properties required for deep-UV NLO applications, including deep-UV transparency, phase-matchability, and sufficiently large second-harmonic generation (1.5 × KH2PO4). Furthermore, it overcomes the structural instability problem of Sr2Be2B2O7, which is confirmed by the obtainment of large single crystals and phonon dispersion calculations. These attributes make it very attractive for next-generation deep-UV NLO materials. The substitution of Be for Al and Li in beryllium borates provides a new opportunity to design beryllium-free deep-UV NLO materials with good performance. PMID:26889570

  3. "Teacher Talk": The Problems, Perspectives and Possibilities of Developing a Comprehensive Sexual Health Education Curriculum for Australian Muslim Students

    ERIC Educational Resources Information Center

    Sanjakdar, Fida

    2009-01-01

    This paper reports on a study that examines how a group of teachers at a Victorian Islamic College deliberated on how to develop an appropriate sexual health education curriculum for their Muslim students. Teachers found themselves challenged by the current restrictive curriculum structures, policies and practices at their school. They also found…

  4. Key Problems in Organizing and Structuring University Research in Vietnam: The Lack of an Effective Research "Behaviour Formalization" System

    ERIC Educational Resources Information Center

    Nguyen, Huong Thi Lan; Meek, Vincent Lynn

    2016-01-01

    Structure and organization seems to be at the root of many of the questions raised about institutional behaviour; however, with respect to research on university capacity building, few studies have examined research organizational problems, particularly in developing countries. This study investigates academic reactions to the structure and…

  5. Structured Group Counseling and Bibliotherapy as In-School Strategies for Preventing Problems in Children from Changing Families.

    ERIC Educational Resources Information Center

    Sheridan, John T.

    The change in family structure precipitated by divorce, separation, death and other parental absences often creates psychological, social and economic problems for some individuals. Of specific interest to school counselors are findings about the effect of changed family structure on children's in-school behavior. The effectiveness of structured…

  6. Error and Uncertainty in the Structure of a Model: A Philosophical Perspective (Invited)

    NASA Astrophysics Data System (ADS)

    Beck, B.; Lin, Z.

    2009-12-01

    Working before the advent of the now commonplace computational model, American pragmatist philosopher Lewis held that there were three elements to the growth of knowledge: the set of concepts; the given data; and those acts which reconcile the data with the concepts. Today, we might call this third element the matter of system identification, or, more precisely, model structure identification. We review briefly the historical developments in dealing with structural error, structural uncertainty, and structural change in models of the behavior of environmental systems. Our focus, however, is on scientific visualization of model structure and the way in which such can assist the process of model structure identification. It is obvious that there has been literally a huge expansion over the decades in our capacity to realize Lewis’s “set of concepts”, as in the ever expanding scope and complexity of our computer-based models, i.e., very high order models (or VHOMs). Together with the oncoming environmental cyber-infrastructure, including novel sensors and sensor technologies, the Environmental Observatories (EOs) of the US National Science Foundation (NSF) share the collective ambition of bringing unprecedented streams of observations to bear on Environmental Science in the decades to come. In short, we can expect a yet further massive expansion in the “given data”. Under such prospects, it has to be the case that Lewis’s “acts” — system identification and, more especially, model structure identification — will likewise be presented with new opportunities for progress and (just as much) confronted with new barriers to be overcome in achieving such progress. Current developments in addressing some of these problems of model structure identification are illustrated using a field case study of nutrient cycling and biomass dynamics in a manipulated aquaculture pond and a simple, hypothetical, biotechnical system. We employ the latter for sharpening our

  7. [Violence and impunity in check: problems and perspectives under the optics of the forensic anthropology in Brazil].

    PubMed

    Lessa, Andrea

    2009-01-01

    Forensic anthropology is playing an increasingly important role facing violence and impunity in many countries. A research performed at police stations of Civil Police and Forensic Institutes of six Brazilian capitals demonstrated that the practice of recover and positive identification of human remains has been neglected in different levels. The main problem is the lack of specific training of the professionals that accomplish the expertise in field and laboratory, but also the fact that no anthropological database of disappeared people is available. As a result of this situation, an expressive number of human remains leave the forensic institutes without positive identification, and criminal inquiries of homicides stay without resolution, contributing to the aggravation of the violence and impunity scenery that devastates the country. PMID:19851598

  8. Problems and Barriers in Ensuring Effective Acute and Post-Operative Pain Management--an International Perspective.

    PubMed

    Mędrzycka-Dąbrowska, Wioletta; Dąbrowski, Sebastian; Basiński, Andrzej

    2015-01-01

    Pain management originated at the turn of the 1960s and 70s in the United States, and spread to Western Europe almost a decade later. It is estimated today that a lack of adequate pain management affects 80% of the global population, and is a serious problem in over 150 countries. At the national level, the greatest burden of inadequate pain management is borne by the elderly, pregnant and breastfeeding women, children, people coping with addictions to harmful substances, and the mentally ill. In spite of enormous progress, there are still significant barriers to comprehensive pain management. Pain management should be considered a priority. It is an interdisciplinary task requiring the cooperation of the whole medical staff. The current review of literature revealed a number of factors limiting the possibility of achieving effective pain management, related to healthcare systems, medical staff and patients. PMID:26768644

  9. Investigating Singapore Pre-Service Teachers' Ill-Structured Problem-Solving Processes in an Asynchronous Online Environment: Implications for Reflective Thinking

    ERIC Educational Resources Information Center

    Ng, Connie S. L.; Tan, Charlene

    2006-01-01

    Background: Solving ill-structured problems is an important aspect in many professions, including the teaching profession. It is therefore appropriate to engage pre-service teachers in solving ill-structured problems. Aim: This study investigates the ill-structured problem-solving processes in an un-moderated asynchronous discussion for one group…

  10. Patch size and distance: modelling habitat structure from the perspective of clonal growth

    PubMed Central

    Oborny, Beáta; Hubai, Andras G.

    2014-01-01

    Background and Aims This study considers the spatial structure of patchy habitats from the perspective of plants that forage for resources by clonal growth. Modelling is used in order to compare two basic strategies, which differ in the response of the plant to a patch boundary. The ‘avoiding plant’ (A) never grows out of a good (resource-rich) patch into a bad (resource-poor) region, because the parent ramet withdraws its subsidy from the offspring. The ‘entering plant’ (E) always crosses the boundary, as the offspring is subsidized at the expense of the parent. In addition to these two extreme scenarios, an intermediate mixed strategy (M) will also be tested. The model is used to compare the efficiency of foraging in various habitats in which the proportion of resource-rich areas (p) is varied. Methods A stochastic cellular automata (CA) model is developed in which habitat space is represented by a honeycomb lattice. Each cell within the lattice can accommodate a single ramet, and colonization can occur from a parent ramet's cell into six neighbouring cells. The CA consists of two layers: the population layer and the habitat. In the population layer, a cell can be empty or occupied by a ramet; in the habitat layer, a cell can be good (resource-rich) or bad (resource-poor). The habitat layer is constant; the population layer changes over time, according to the birth and death of ramets. Key Results Strategies M and E are primarily limited by patch distance, whereas A is more sensitive to patch size. At a critical threshold of the proportion of resource-rich areas, p = 0·5, the mean patch size increases abruptly. Below the threshold, E is more efficient than A, whilst above the threshold the opposite is true. The mixed strategy (M) is more efficient than either of the pure strategies across a broad range of p values. Conclusions The model predicts more species/genotypes with the ‘entering’ strategy, E, in habitats where resource-rich patches are

  11. A review of maturation diets for mud crab genus Scylla broodstock: Present research, problems and future perspective

    PubMed Central

    Azra, Mohamad N.; Ikhwanuddin, Mhd

    2015-01-01

    Study of broodstock maturation diets is important in order to increase the quality of berried females, which indirectly improve the larval quantity in the hatchery production of cultured species. This paper reviewed the studies on the maturation diets for mud crab broodstock, genus Scylla and compared independently to identify their effect on reproductive performance and larval quality. The broodstock is usually caught from the wild and held in the spawning or maturation tank for further use of hatchery seed production. Mud crab broodstock was fed either natural diet, artificial diet or mixed diet. Trash fishes were commonly used as a natural feed for mud crab broodstock; meanwhile artificial diets are from formulated fish meal and various kinds of feed. The results indicated that mud crab broodstock has a high dietary requirement for lipids, fatty acids and protein which are to be used during the maturation and breeding processes. However, the natural diet produce better larval quality compared to the artificial diet. The mixed diet is the better diet which resulted in better reproductive performances such as growth, survival, fecundity and maturation processes. This review also discusses the problems in the previous studies for the potential future research to develop very high quality and cost-effective formulated diet for the enhancement of broodstock and seed production technology. Information from this review can be useful in developing a better quality of crustacean broodstock’s diet for commercial hatchery production. PMID:26981008

  12. Indian medical students’ perspectives on problem-based learning experiences in the undergraduate curriculum: One size does not fit all

    PubMed Central

    2013-01-01

    Purpose: Problem-based learning (PBL) is a well-established method for facilitating the learning of basic science concepts in the context of clinical cases. Relevant evidence is lacking regarding PBL’s effectiveness and acceptability as perceived by students accustomed to classical traditional teaching in India. Hence, this study gathered students’ opinions on PBL versus Traditional teaching methods to generate a foundation for institutional policymaking and ultimately, changes in the policy of regulatory bodies. Methods: A total of 773 first year medical students admitted from 2007-2010 in Kasturba Medical College Manipal, Manipal University, India were asked to respond to a 15-item questionnaire evaluating their preferences for PBL or traditional methods such as lectures after undergoing a systematically conducted PBL session in physiology. Their responses were analyzed with an unpaired t-test. Their comments were also collected. Results: PBL scored significantly higher for most items in the questionnaire for “learning efficiency” and “student-teacher relationship”. The students’ comments highlighted the importance of a trained tutor/facilitator to enhance the learning process. Conclusion: Our students are willing to adapt to the PBL method, although they recognize certain benefits of traditional pedagogy. For learning efficiency and the student-teacher relationship, the students feel that neither method holds an advantage. We recommend that the future medical curriculum in India be a hybrid form of PBL and traditional methods with specific training on the unfamiliar PBL approach for both faculty and students. PMID:24498472

  13. A review of maturation diets for mud crab genus Scylla broodstock: Present research, problems and future perspective.

    PubMed

    Azra, Mohamad N; Ikhwanuddin, Mhd

    2016-03-01

    Study of broodstock maturation diets is important in order to increase the quality of berried females, which indirectly improve the larval quantity in the hatchery production of cultured species. This paper reviewed the studies on the maturation diets for mud crab broodstock, genus Scylla and compared independently to identify their effect on reproductive performance and larval quality. The broodstock is usually caught from the wild and held in the spawning or maturation tank for further use of hatchery seed production. Mud crab broodstock was fed either natural diet, artificial diet or mixed diet. Trash fishes were commonly used as a natural feed for mud crab broodstock; meanwhile artificial diets are from formulated fish meal and various kinds of feed. The results indicated that mud crab broodstock has a high dietary requirement for lipids, fatty acids and protein which are to be used during the maturation and breeding processes. However, the natural diet produce better larval quality compared to the artificial diet. The mixed diet is the better diet which resulted in better reproductive performances such as growth, survival, fecundity and maturation processes. This review also discusses the problems in the previous studies for the potential future research to develop very high quality and cost-effective formulated diet for the enhancement of broodstock and seed production technology. Information from this review can be useful in developing a better quality of crustacean broodstock's diet for commercial hatchery production. PMID:26981008

  14. Magnetohydrodynamic Riemann problem and the structure of the magnetic reconnection layer

    NASA Technical Reports Server (NTRS)

    Wu, C. C.

    1995-01-01

    We present a complete solution for a set of magnetohydrodynamic (MHD) Riemann problems in which the upstream and downstream states have the same total pressure, and in which the normal component of the magnetic field is very small. These solutions are pertinent to subfast flows in the earth's magnetic tail and near the magnetopause. In a coplanar situation a family of solutions exists that depend on two parameters as well as on dissapation mechanisms. In the parallel case the transverse magnetic field either does not change direction or changes the direction twice by involving two intermediate shocks. In the antiparallel case an intermediate shock is always required, except when the solution consists of two switch-off shocks. In a noncoplanar case the solution is not self-similar as a function of x/t, but continues to evolve. At early times the evolution is similar to the coplanar case. In general two time-dependent intermediate shocks are required to rotate the magnetic fields. The velocity shear has a strong effect on the Riemann solution. In some cases no Riemann solution can exist because of the cavitation caused by the slow refraction waves. The calculated magnetopause structure resembles the observed structure for northward interplanetary magnetic field (IMF). However, for southward IMF, the MHD result shows the existence of a depletion layer, which is not supported by observations. We also show that on the magnetosheath side, the Walen relation, which is exact for a rotational discontinuity, can also be well satisfied by a slow shock, an intermediate shock, or the head of a slow rarefaction wave.

  15. Child Development within Culturally Structured Environments. Volume 3: Comparative-Cultural and Constructivist Perspectives.

    ERIC Educational Resources Information Center

    Valsiner, Jaan, Ed.

    Using a comparative-cultural perspective, this collection of essays examines the co-constructivist nature of human development in culturally organized environments. The contributions also cover a large age span--infancy to adulthood. Chapters in part 1 cover two different directions in the study of early adult-infant interaction from a comparative…

  16. School Structure and the Identity of Teacher Leaders: Perspectives of Principals and Teachers

    ERIC Educational Resources Information Center

    Angelle, Pamela S.; Schmid, Jessie B.

    2007-01-01

    This qualitative study examines the concept of teacher leadership from the perspective of those who practice it. Viewed through the lens of identity theory, analysis yielded five categories that define and describe a teacher leader--namely, as a decision maker, an educational role model, a positional designee, a supra-practitioner, and a…

  17. Psychosocial Problems among Truant Youths: A Multi-Group, Exploratory Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C.; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven

    2012-01-01

    Truant youths represent a critical group needing problem-oriented research and involvement in effective services. The limited number of studies on the psychosocial functioning of truant youths have focused on one or a few problem areas, rather than examining comorbid problem behaviors. The present study addresses the need to examine the…

  18. From video to computation of biological fluid-structure interaction problems

    NASA Astrophysics Data System (ADS)

    Dillard, Seth I.; Buchholz, James H. J.; Udaykumar, H. S.

    2016-04-01

    This work deals with the techniques necessary to obtain a purely Eulerian procedure to conduct CFD simulations of biological systems with moving boundary flow phenomena. Eulerian approaches obviate difficulties associated with mesh generation to describe or fit flow meshes to body surfaces. The challenges associated with constructing embedded boundary information, body motions and applying boundary conditions on the moving bodies for flow computation are addressed in the work. The overall approach is applied to the study of a fluid-structure interaction problem, i.e., the hydrodynamics of swimming of an American eel, where the motion of the eel is derived from video imaging. It is shown that some first-blush approaches do not work, and therefore, careful consideration of appropriate techniques to connect moving images to flow simulations is necessary and forms the main contribution of the paper. A combination of level set-based active contour segmentation with optical flow and image morphing is shown to enable the image-to-computation process.

  19. Low Dimensional Tools for Flow-Structure Interaction Problems: Application to Micro Air Vehicles

    NASA Technical Reports Server (NTRS)

    Schmit, Ryan F.; Glauser, Mark N.; Gorton, Susan A.

    2003-01-01

    A low dimensional tool for flow-structure interaction problems based on Proper Orthogonal Decomposition (POD) and modified Linear Stochastic Estimation (mLSE) has been proposed and was applied to a Micro Air Vehicle (MAV) wing. The method utilizes the dynamic strain measurements from the wing to estimate the POD expansion coefficients from which an estimation of the velocity in the wake can be obtained. For this experiment the MAV wing was set at five different angles of attack, from 0 deg to 20 deg. The tunnel velocities varied from 44 to 58 ft/sec with corresponding Reynolds numbers of 46,000 to 70,000. A stereo Particle Image Velocimetry (PIV) system was used to measure the wake of the MAV wing simultaneously with the signals from the twelve dynamic strain gauges mounted on the wing. With 20 out of 2400 POD modes, a reasonable estimation of the flow flow was observed. By increasing the number of POD modes, a better estimation of the flow field will occur. Utilizing the simultaneously sampled strain gauges and flow field measurements in conjunction with mLSE, an estimation of the flow field with lower energy modes is reasonable. With these results, the methodology for estimating the wake flow field from just dynamic strain gauges is validated.

  20. Combined aerodynamic and structural dynamic problem emulating routines (CASPER): Theory and implementation

    NASA Technical Reports Server (NTRS)

    Jones, William H.

    1985-01-01

    The Combined Aerodynamic and Structural Dynamic Problem Emulating Routines (CASPER) is a collection of data-base modification computer routines that can be used to simulate Navier-Stokes flow through realistic, time-varying internal flow fields. The Navier-Stokes equation used involves calculations in all three dimensions and retains all viscous terms. The only term neglected in the current implementation is gravitation. The solution approach is of an interative, time-marching nature. Calculations are based on Lagrangian aerodynamic elements (aeroelements). It is assumed that the relationships between a particular aeroelement and its five nearest neighbor aeroelements are sufficient to make a valid simulation of Navier-Stokes flow on a small scale and that the collection of all small-scale simulations makes a valid simulation of a large-scale flow. In keeping with these assumptions, it must be noted that CASPER produces an imitation or simulation of Navier-Stokes flow rather than a strict numerical solution of the Navier-Stokes equation. CASPER is written to operate under the Parallel, Asynchronous Executive (PAX), which is described in a separate report.

  1. Iterative solution of multiple radiation and scattering problems in structural acoustics using the BL-QMR algorithm

    SciTech Connect

    Malhotra, M.

    1996-12-31

    Finite-element discretizations of time-harmonic acoustic wave problems in exterior domains result in large sparse systems of linear equations with complex symmetric coefficient matrices. In many situations, these matrix problems need to be solved repeatedly for different right-hand sides, but with the same coefficient matrix. For instance, multiple right-hand sides arise in radiation problems due to multiple load cases, and also in scattering problems when multiple angles of incidence of an incoming plane wave need to be considered. In this talk, we discuss the iterative solution of multiple linear systems arising in radiation and scattering problems in structural acoustics by means of a complex symmetric variant of the BL-QMR method. First, we summarize the governing partial differential equations for time-harmonic structural acoustics, the finite-element discretization of these equations, and the resulting complex symmetric matrix problem. Next, we sketch the special version of BL-QMR method that exploits complex symmetry, and we describe the preconditioners we have used in conjunction with BL-QMR. Finally, we report some typical results of our extensive numerical tests to illustrate the typical convergence behavior of BL-QMR method for multiple radiation and scattering problems in structural acoustics, to identify appropriate preconditioners for these problems, and to demonstrate the importance of deflation in block Krylov-subspace methods. Our numerical results show that the multiple systems arising in structural acoustics can be solved very efficiently with the preconditioned BL-QMR method. In fact, for multiple systems with up to 40 and more different right-hand sides we get consistent and significant speed-ups over solving the systems individually.

  2. Studying illicit drug trafficking on Darknet markets: Structure and organisation from a Canadian perspective.

    PubMed

    Broséus, J; Rhumorbarbe, D; Mireault, C; Ouellette, V; Crispino, F; Décary-Hétu, D

    2016-07-01

    Cryptomarkets are online marketplaces that are part of the Dark Web and mainly devoted to the sale of illicit drugs. They combine tools to ensure anonymity of participants with the delivery of products by mail to enable the development of illicit drug trafficking. Using data collected on eight cryptomarkets, this study provides an overview of the Canadian illicit drug market. It seeks to inform about the most prevalent illicit drugs vendors offer for sale and preferred destination countries. Moreover, the research gives an insight into the structure and organisation of distribution networks existing online. In particular, we provide information about how vendors are diversifying and replicating across marketplaces. We inform on the number of listings each vendor manages, the number of cryptomarkets they are active on and the products they offer. This research demonstrates the importance of online marketplaces in the context of illicit drug trafficking. It shows how the analysis of data available online may elicit knowledge on criminal activities. Such knowledge is mandatory to design efficient policy for monitoring or repressive purposes against anonymous marketplaces. Nevertheless, trafficking on Dark Net markets is difficult to analyse based only on digital data. A more holistic approach for investigating this crime problem should be developed. This should rely on a combined use and interpretation of digital and physical data within a single collaborative intelligence model. PMID:26978791

  3. Public Investments in Training: Perspectives on Macro-Level Structural Issues and Micro-Level Delivery Systems. EQW Working Papers WP24.

    ERIC Educational Resources Information Center

    Cascio, Wayne F.

    Training issues can be examined from at least two perspectives: the structural level (macro-level) and the micro-level. Structural issues in the delivery of training include the following: absent or uneven corporate commitment, inadequate expenditures by businesses, degrees awarded by schools that do not guarantee skill mastery, poaching of…

  4. Structural Damage Prediction and Analysis for Hypervelocity Impact. BUMPERII Suggestion and Problem Reports

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the course of preparing the SD_SURF space debris analysis code, several problems and possibilities for improvement of the BUMPERII code were documented and sent to MSFC. These suggestions and problem reports are included here as a part of the contract final report. This includes reducing BUMPERII memory requirements, compiling problems with BUMPERII, FORTRAN-lint analysis of BUMPERII, and error in function PRV in BUMPERII.

  5. Can ill-structured problems reveal beliefs about medical knowledge and knowing? A focus-group approach

    PubMed Central

    Roex, Ann; Clarebout, Geraldine; Dory, Valerie; Degryse, Jan

    2009-01-01

    Background Epistemological beliefs (EB) are an individual's cognitions about knowledge and knowing. In several non-medical domains, EB have been found to contribute to the way individuals reason when faced with ill-structured problems (i.e. problems with no clear-cut, right or wrong solutions). Such problems are very common in medical practice. Determining whether EB are also influential in reasoning processes with regard to medical issues to which there is no straightforward answer, could have implications for medical education. This study focused on 2 research questions: 1. Can ill-structured problems be used to elicit general practice trainees' and trainers' EB? and 2. What are the views of general practice trainees and trainers about knowledge and how do they justify knowing? Methods 2 focus groups of trainees (n = 18) were convened on 3 occasions during their 1st year of postgraduate GP training. 2 groups of GP trainers (n = 11) met on one occasion. Based on the methodology of the Reflective Judgement Interview (RJI), participants were asked to comment on 11 ill-structured problems. The sessions were audio taped and transcribed and an adapted version of the RJI scoring rules was used to assess the trainees' reasoning about ill-structured problems. Results Participants made a number of statements illustrating their EB and their importance in clinical reasoning. The level of EB varied widely form one meeting to another and depending on the problem addressed. Overall, the EB expressed by trainees did not differ from those of trainers except on a particular ill-structured problem regarding shoulder pain. Conclusion The use of focus groups has entailed some difficulties in the interpretation of the results, but a number of preliminary conclusions can be drawn. Ill-structured medical problems can be used to elicit EB. Most trainees and trainers displayed pre-reflective and quasi-reflective EB. The way trainees and doctors view and justify knowledge are likely to be

  6. Family Structure and Problem Behavior of Adolescents and Young Adults: A Growth-Curve Study

    ERIC Educational Resources Information Center

    VanderValk, Inge; Spruijt, Ed; de Goede, Matijn; Maas, Cora; Meeus, Wim

    2005-01-01

    In the present longitudinal 3-wave study of 1274 adolescents and young adults, aged 12-24 at the 1st wave, it is examined whether youngsters from intact versus postdivorce families show long-term differences in internalizing and externalizing problems. Furthermore, possible differences in the development of this problem behavior between offspring…

  7. Behavior Problems among Children from Different Family Structures: The Influence of Genetic Self-Selection.

    ERIC Educational Resources Information Center

    Cleveland, H. Harrington; Wiebe, Richard P.; van den Oord, Edwin J. C. G.; Rowe, David C.

    2000-01-01

    Examined influences on children's behavior problems in households defined by marital status and sibling relatedness. Found that genetic influences accounted for 81 to 94 percent of mean-level difference in behavior problems between two-parent/full sibling, and the mother-only/half sibling groups. Shared environmental influences accounted for 67 to…

  8. Development of the Structured Problem Posing Skills and Using Metaphoric Perceptions

    ERIC Educational Resources Information Center

    Arikan, Elif Esra; Unal, Hasan

    2014-01-01

    The purpose of this study was to introduce problem posing activity to third grade students who have never met before. This study was also explored students' metaphorical images on problem posing process. Participants were from Public school in Marmara Region in Turkey. Data was analyzed both qualitatively (content analysis for difficulty and…

  9. Hypersonic structures: An aerodynamicist's perspective, or one man's dream is another man's nightmare

    NASA Technical Reports Server (NTRS)

    Watts, J. D.; Jackson, L. R.; Hunt, J. L.

    1978-01-01

    The relationship between hypersonic aerodynamic and structural design is reviewed. The evolution of the hypersonic vehicle design is presented. Propulsion systems, structural materials, and fuels are emphasized.

  10. Identifying Configurations of Perceived Teacher Autonomy Support and Structure: Associations with Self-Regulated Learning, Motivation and Problem Behavior

    ERIC Educational Resources Information Center

    Vansteenkiste, Maarten; Sierens, Eline; Goossens, Luc; Soenens, Bart; Dochy, Filip; Mouratidis, Athanasios; Aelterman, Nathalie; Haerens, Leen; Beyers, Wim

    2012-01-01

    Grounded in self-determination theory, the aim of this study was (a) to examine naturally occurring configurations of perceived teacher autonomy support and clear expectations (i.e., a central aspect of teacher structure), and (b) to investigate associations with academic motivation, self-regulated learning, and problem behavior. Based on…

  11. Issues in Implementing a Structured Problem-Based Learning Strategy in a Volcano Unit: A Case Study

    ERIC Educational Resources Information Center

    Lee, Hyunju; Bae, Sungah

    2008-01-01

    The purpose of this study was to understand how an 8th grade science class used a structured problem-based learning (PBL) strategy to study volcanoes and to discuss some of the issues that science teachers might encounter when designing and implementing the PBL strategy. This study took place at Collins Middle School, which is located in a…

  12. Effect of structure in problem based learning on science teaching efficacy beliefs and science content knowledge of elementary preservice teachers

    NASA Astrophysics Data System (ADS)

    Sasser, Selena Kay

    This study examined the effects of differing amounts of structure within the problem based learning instructional model on elementary preservice teachers' science teaching efficacy beliefs, including personal science teaching efficacy and science teaching outcome expectancy, and content knowledge acquisition. This study involved sixty (60) undergraduate elementary preservice teachers enrolled in three sections of elementary science methods classes at a large Midwestern research university. This study used a quasi-experimental nonequivalent design to collect and analyze both quantitative and qualitative data. Participants completed instruments designed to assess science teaching efficacy beliefs, science background, and demographic data. Quantitative data from pre and posttests was obtained using the science teaching efficacy belief instrument-preservice (STEBI-B) developed by Enochs and Riggs (1990) and modified by Bleicher (2004). Data collection instruments also included a demographic questionnaire, an analytic rubric, and a structured interview; both created by the researcher. Quantitative data was analyzed by conducting ANCOVA, paired samples t-test, and independent samples t-test. Qualitative data was analyzed using coding and themes. Each of the treatment groups received the same problem scenario, one group experienced a more structured PBL setting, and one group experienced a limited structure PBL setting. Research personnel administered pre and posttests to determine the elementary preservice teachers' science teaching efficacy beliefs. The results show elementary preservice teachers'science teaching efficacy beliefs can be influence by the problem based learning instructional model. This study did not find that the amount of structure in the form of core ideas to consider and resources for further research increased science teaching efficacy beliefs in this sample. Results from the science content knowledge rubric indicated that structure can increase

  13. ET-Motif: Solving the Exact (l, d)-Planted Motif Problem Using Error Tree Structure.

    PubMed

    Al-Okaily, Anas; Huang, Chun-Hsi

    2016-07-01

    Motif finding is an important and a challenging problem in many biological applications such as discovering promoters, enhancers, locus control regions, transcription factors, and more. The (l, d)-planted motif search, PMS, is one of several variations of the problem. In this problem, there are n given sequences over alphabets of size [Formula: see text], each of length m, and two given integers l and d. The problem is to find a motif m of length l, where in each sequence there is at least an l-mer at a Hamming distance of [Formula: see text] of m. In this article, we propose ET-Motif, an algorithm that can solve the PMS problem in [Formula: see text] time and [Formula: see text] space. The time bound can be further reduced by a factor of m with [Formula: see text] space. In case the suffix tree that is built for the input sequences is balanced, the problem can be solved in [Formula: see text] time and [Formula: see text] space. Similarly, the time bound can be reduced by a factor of m using [Formula: see text] space. Moreover, the variations of the problem, namely the edit distance PMS and edited PMS (Quorum), can be solved using ET-Motif with simple modifications but upper bands of space and time. For edit distance PMS, the time and space bounds will be increased by [Formula: see text], while for edited PMS the increase will be of [Formula: see text] in the time bound. PMID:27152692

  14. Molecular structure matching by simulated annealing. II. An exploration of the evolution of configuration landscape problems.

    PubMed

    Barakat, M T; Dean, P M

    1990-09-01

    This paper considers some of the landscape problems encountered in matching molecules by simulated annealing. Although the method is in theory ergodic, the global minimum in the objective function is not always encountered. Factors inherent in the molecular data that lead the trajectory of the minimization away from its optimal route are analysed. Segments comprised of the C alpha atoms of dihydrofolate reductase are used as test data. The evolution of a reverse ordering landscape problem is examined in detail. Where such patterns in the data could lead to incorrect matches, the problem can in part be circumvented by assigning an initial random ordering to the molecules. PMID:2280267

  15. Problems and perspectives in paraplegia

    NASA Technical Reports Server (NTRS)

    Nashold, B.

    1974-01-01

    Improved clinical treatment of the paraplegic, developed during World War II, has reduced the overall mortality rate from close to 100 percent to 30 percent. Despite major clinical improvements, mainly in treatment of the acute phase of paraplegia, and despite greater rehabilitation efforts, the spinal injured person is never rehabilitated in the sense that he reaches an optimum and stays there. He is always exposed to the constant threat of deterioration of his physiological, sociological, and psychological state.

  16. Image databases: Problems and perspectives

    NASA Technical Reports Server (NTRS)

    Gudivada, V. Naidu

    1989-01-01

    With the increasing number of computer graphics, image processing, and pattern recognition applications, economical storage, efficient representation and manipulation, and powerful and flexible query languages for retrieval of image data are of paramount importance. These and related issues pertinent to image data bases are examined.

  17. Rediscovery in a Course for Nonscientists: Use of Molecular Models to Solve Classical Structural Problems

    ERIC Educational Resources Information Center

    Wood, Gordon W.

    1975-01-01

    Describes exercises using simple ball and stick models which students with no chemistry background can solve in the context of the original discovery. Examples include the tartaric acid and benzene problems. (GS)

  18. Parents and peer group as mediators of the effect of community structure on adolescent problem behavior.

    PubMed

    Simons, R L; Johnson, C; Beaman, J; Conger, R D; Whitbeck, L B

    1996-02-01

    Used a sample of 207 single-parent families residing in 104 small, Midwestern communities to test hypotheses regarding the link between community context and adolescent conduct problems and psychological distress. For boys, community disadvantage had a direct affect on psychological distress, while it indirectly boosted the probability of conduct problems by disrupting parenting and increasing affiliation with deviant peers. Community disadvantage was unrelated to the deviant behavior or emotional well-being of girls. Proportion of single-parent households in the community had a direct effect on girls' conduct problems. It also contributed indirectly to girls' conduct problems by increasing the probability of involvement with deviant peers. Possible explanations for these gender differences are provided. PMID:8712184

  19. On the interaction structure of linear multi-input feedback control systems. M.S. Thesis; [problem solving, lattices (mathematics)

    NASA Technical Reports Server (NTRS)

    Wong, P. K.

    1975-01-01

    The closely-related problems of designing reliable feedback stabilization strategy and coordinating decentralized feedbacks are considered. Two approaches are taken. A geometric characterization of the structure of control interaction (and its dual) was first attempted and a concept of structural homomorphism developed based on the idea of 'similarity' of interaction pattern. The idea of finding classes of individual feedback maps that do not 'interfere' with the stabilizing action of each other was developed by identifying the structural properties of nondestabilizing and LQ-optimal feedback maps. Some known stability properties of LQ-feedback were generalized and some partial solutions were provided to the reliable stabilization and decentralized feedback coordination problems. A concept of coordination parametrization was introduced, and a scheme for classifying different modes of decentralization (information, control law computation, on-line control implementation) in control systems was developed.

  20. Development and Applications of a Modular Parallel Process for Large Scale Fluid/Structures Problems

    NASA Technical Reports Server (NTRS)

    Guruswamy, Guru P.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    A modular process that can efficiently solve large scale multidisciplinary problems using massively parallel supercomputers is presented. The process integrates disciplines with diverse physical characteristics by retaining the efficiency of individual disciplines. Computational domain independence of individual disciplines is maintained using a meta programming approach. The process integrates disciplines without affecting the combined performance. Results are demonstrated for large scale aerospace problems on several supercomputers. The super scalability and portability of the approach is demonstrated on several parallel computers.