The development of personality extremity from childhood to adolescence: relations to internalizing and externalizing problems

NARCIS (Netherlands)

van den Akker, A.L.; Prinzie, P.; Deković, M.; de Haan, A.D.; Asscher, J.J.; Widiger, T.

2013-01-01

This study investigated the development of personality extremity (deviation of an average midpoint of all 5 personality dimensions together) across childhood and adolescence, as well as relations between personality extremity and adjustment problems. For 598 children (mean age at Time 1 = 7.5

Identification of Climate Change with Generalized Extreme Value (GEV) Distribution Approach

International Nuclear Information System (INIS)

Rahayu, Anita

2013-01-01

Some events are difficult to avoid and gives considerable influence to humans and the environment is extreme weather and climate change. Many of the problems that require knowledge about the behavior of extreme values and one of the methods used are the Extreme Value Theory (EVT). EVT used to draw up reliable systems in a variety of conditions, so as to minimize the risk of a major disaster. There are two methods for identifying extreme value, Block Maxima with Generalized Extreme Value (GEV) distribution approach and Peaks over Threshold (POT) with Generalized Pareto Distribution (GPD) approach. This research in Indramayu with January 1961-December 2003 period, the method used is Block Maxima with GEV distribution approach. The result showed that there is no climate change in Indramayu with January 1961-December 2003 period.

A technical solution to a difficult problem - An update

International Nuclear Information System (INIS)

Asselstine, J.K.

1985-01-01

A goal of the Reduced Enrichment Research and Test Reactor Program (RERTR) established by the U.S. Department of Energy is to develop the technical means needed to utilize LEU instead of HEU fuels in research and test reactors and to do so without operational penalties and without affecting safety characteristics. This goal has been pursued now for seven years in cooperation with many of you who are participants in this conference. The program has made significant progress in the development, demonstration and application of new LEU research reactor fuels. According to recent projections, the percentage of HEU fuel in international commerce which is technically replaceable with LEU fuels has been growing steadily as research continues. There appears to be no technical barrier to eventual replacement of HEU fuel with LEU fuel in research and test reactors. While there are many politically complex and technically difficult issues involved in nonproliferation, I conclude that the use of highly enriched weapons grade uranium as a fuel in civilian research reactors stands out as one problem which has a straight forward technical solution. The technical solution is the effort you in the RERTR program are embarked on. Once that solution is in hand, the operators of research reactors are urged to take political and legal initiatives to make the conversion happen. By effecting this conversion they will help minimize the trade in highly enriched uranium and make the world a little safer

A technical solution to a difficult problem - An update

Energy Technology Data Exchange (ETDEWEB)

Asselstine, J K

1985-07-01

A goal of the Reduced Enrichment Research and Test Reactor Program (RERTR) established by the U.S. Department of Energy is to develop the technical means needed to utilize LEU instead of HEU fuels in research and test reactors and to do so without operational penalties and without affecting safety characteristics. This goal has been pursued now for seven years in cooperation with many of you who are participants in this conference. The program has made significant progress in the development, demonstration and application of new LEU research reactor fuels. According to recent projections, the percentage of HEU fuel in international commerce which is technically replaceable with LEU fuels has been growing steadily as research continues. There appears to be no technical barrier to eventual replacement of HEU fuel with LEU fuel in research and test reactors. While there are many politically complex and technically difficult issues involved in nonproliferation, I conclude that the use of highly enriched weapons grade uranium as a fuel in civilian research reactors stands out as one problem which has a straight forward technical solution. The technical solution is the effort you in the RERTR program are embarked on. Once that solution is in hand, the operators of research reactors are urged to take political and legal initiatives to make the conversion happen. By effecting this conversion they will help minimize the trade in highly enriched uranium and make the world a little safer.

Diagnosis and management of deep vein thrombosis of the upper extremity: a review

International Nuclear Information System (INIS)

Baarslag, Henk J.; Reekers, Jim A.; Koopman, Maria M.W.; Beek, Edwin J.R. van

2004-01-01

Deep vein thrombosis of the upper extremity is an increasing clinical problem due to the use of long-term indwelling catheters for chemotherapy or long-term feeding. The clinical diagnosis is difficult to make, and various imaging modalities have been used for this purpose. The use of (interventional) radiological procedures has been advancing in recent years. This review describes the clinical background, the imaging modalities that may be employed, treatment options and outcome of patients with upper extremity thrombosis. (orig.)

Statistical techniques for modeling extreme price dynamics in the energy market

International Nuclear Information System (INIS)

Mbugua, L N; Mwita, P N

2013-01-01

Extreme events have large impact throughout the span of engineering, science and economics. This is because extreme events often lead to failure and losses due to the nature unobservable of extra ordinary occurrences. In this context this paper focuses on appropriate statistical methods relating to a combination of quantile regression approach and extreme value theory to model the excesses. This plays a vital role in risk management. Locally, nonparametric quantile regression is used, a method that is flexible and best suited when one knows little about the functional forms of the object being estimated. The conditions are derived in order to estimate the extreme value distribution function. The threshold model of extreme values is used to circumvent the lack of adequate observation problem at the tail of the distribution function. The application of a selection of these techniques is demonstrated on the volatile fuel market. The results indicate that the method used can extract maximum possible reliable information from the data. The key attraction of this method is that it offers a set of ready made approaches to the most difficult problem of risk modeling.

Bidirectional extreme learning machine for regression problem and its learning effectiveness.

Science.gov (United States)

Yang, Yimin; Wang, Yaonan; Yuan, Xiaofang

2012-09-01

It is clear that the learning effectiveness and learning speed of neural networks are in general far slower than required, which has been a major bottleneck for many applications. Recently, a simple and efficient learning method, referred to as extreme learning machine (ELM), was proposed by Huang , which has shown that, compared to some conventional methods, the training time of neural networks can be reduced by a thousand times. However, one of the open problems in ELM research is whether the number of hidden nodes can be further reduced without affecting learning effectiveness. This brief proposes a new learning algorithm, called bidirectional extreme learning machine (B-ELM), in which some hidden nodes are not randomly selected. In theory, this algorithm tends to reduce network output error to 0 at an extremely early learning stage. Furthermore, we find a relationship between the network output error and the network output weights in the proposed B-ELM. Simulation results demonstrate that the proposed method can be tens to hundreds of times faster than other incremental ELM algorithms.

What Makes Difficult History Difficult?

Science.gov (United States)

Gross, Magdalena H.; Terra, Luke

2018-01-01

All modern nation-states have periods of difficult history that teachers fail to address or address inadequately. The authors present a framework for defining difficult histories and understanding what makes them difficult. These events 1) are central to a nation's history, 2) contradict accepted histories or values, 3) connect with present…

Image-guided ablation of painful metastatic bone tumors: a new and effective approach to a difficult problem

International Nuclear Information System (INIS)

Callstrom, Matthew R.; Charboneau, J. William; Atwell, Thomas D.; Farrell, Michael A.; Welch, Timothy J.; Maus, Timothy P.; Goetz, Matthew P.; Rubin, Joseph

2006-01-01

Painful skeletal metastases are a common problem in cancer patients. Although external beam radiation therapy is the current standard of care for cancer patients who present with localized bone pain, 20-30% of patients treated with this modality do not experience pain relief, and few further options exist for these patients. For many patients with painful metastatic skeletal disease, analgesics remain the only alternative treatment option. Recently, image-guided percutaneous methods of tumor destruction have proven effective for treatment of this difficult problem. This review describes the application, limitations, and effectiveness of percutaneous ablative methods including ethanol, methyl methacrylate, laser-induced interstitial thermotherapy (LITT), cryoablation, and percutaneous radiofrequency ablation (RFA) for palliation of painful skeletal metastases. (orig.)

Crisis management during anaesthesia: difficult intubation.

Science.gov (United States)

Paix, A D; Williamson, J A; Runciman, W B

2005-06-01

Anaesthetists may experience difficulty with intubation unexpectedly which may be associated with difficulty in ventilating the patient. If not well managed, there may be serious consequences for the patient. A simple structured approach to this problem was developed to assist the anaesthetist in this difficult situation. To examine the role of a specific sub-algorithm for the management of difficult intubation. The potential performance of a structured approach developed by review of the literature and analysis of each of the relevant incidents among the first 4000 reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual management as reported by the anaesthetists involved. There were 147 reports of difficult intubation capable of analysis among the first 4000 incidents reported to AIMS. The difficulty was unexpected in 52% of cases; major physiological changes occurred in 37% of these cases. Saturation fell below 90% in 22% of cases, oesophageal intubation was reported in 19%, and an emergency transtracheal airway was required in 4% of cases. Obesity and limited neck mobility and mouth opening were the most common anatomical contributing factors. The data confirm previously reported failures to predict difficult intubation with existing preoperative clinical tests and suggest an ongoing need to teach a pre-learned strategy to deal with difficult intubation and any associated problem with ventilation. An easy-to-follow structured approach to these problems is outlined. It is recommended that skilled assistance be obtained (preferably another anaesthetist) when difficulty is expected or the patient's cardiorespiratory reserve is low. Patients should be assessed postoperatively to exclude any sequelae and to inform them of the difficulties encountered. These should be clearly documented and appropriate steps taken to warn future anaesthetists.

Non-Supersymmetric (but) Extreme Black Holes, Scalar Hair and Other Open Problems

CERN Document Server

Ortín, Tomas

1999-01-01

We give a brief overview of black-hole solutions in four-dimensional supergravity theories and their extremal and supersymmetric limits. We also address problems like cosmic censorship and no-hair theorems in supergravity theories. While supergravity by itself seems not to be enough to enforce cosmic censorship and absence of primary scalar hair, superstring theory may be.

Beyond Psychometrics: The Difference between Difficult Problem Solving and Complex Problem Solving

Directory of Open Access Journals (Sweden)

Jens F. Beckmann

2017-10-01

Full Text Available In this paper we argue that a synthesis of findings across the various sub-areas of research in complex problem solving and consequently progress in theory building is hampered by an insufficient differentiation of complexity and difficulty. In the proposed framework of person, task, and situation (PTS, complexity is conceptualized as a quality that is determined by the cognitive demands that the characteristics of the task and the situation impose. Difficulty represents the quantifiable level of a person’s success in dealing with such demands. We use the well-documented “semantic effect” as an exemplar for testing some of the conceptual assumptions derived from the PTS framework. We demonstrate how a differentiation between complexity and difficulty can help take beyond a potentially too narrowly defined psychometric perspective and subsequently gain a better understanding of the cognitive mechanisms behind this effect. In an empirical study a total of 240 university students were randomly allocated to one of four conditions. The four conditions resulted from contrasting the semanticity level of the variable labels used in the CPS system (high vs. low and two instruction conditions for how to explore the CPS system’s causal structure (starting with the assumption that all relationships between variables existed vs. starting with the assumption that none of the relationships existed. The variation in the instruction aimed at inducing knowledge acquisition processes of either (1 systematic elimination of presumptions, or (2 systematic compilation of a mental representation of the causal structure underpinning the system. Results indicate that (a it is more complex to adopt a “blank slate” perspective under high semanticity as it requires processes of inhibiting prior assumptions, and (b it seems more difficult to employ a systematic heuristic when testing against presumptions. In combination, situational characteristics, such as the

Countering the Pedagogy of Extremism: Reflective Narratives and Critiques of Problem-Based Learning

Science.gov (United States)

Woo, Chris W. H.; Laxman, Kumar

2013-01-01

This paper is a critique against "purist" pedagogies found in the literature of student-centred learning. The article reproves extremism in education and questions the absolutism and teleological truths expounded in exclusive problem-based learning. The paper articulates the framework of a unifying pedagogical practice through Eve…

Extreme value problems without calculus: a good link with geometry and elementary maths

Science.gov (United States)

Ganci, Salvatore

2016-11-01

Some classical examples of problem solving, where an extreme value condition is required, are here considered and/or revisited. The search for non-calculus solutions appears pedagogically useful and intriguing as shown through a rich literature. A teacher, who teaches both maths and physics, (as happens in Italian High schools) can find in these kinds of problems a mind stimulating exercise compared with the standard solution obtained by the differential calculus. A good link between the geometric and analytical explanations is so established.

Problems in psychiatric care of 'difficult patients': a Delphi-study

NARCIS (Netherlands)

Koekkoek, Bauke; van Meijel, Berno; Schene, Aart; Hutschemaekers, Giel

2009-01-01

'difficult patients' may evoke strong feelings in health professionals. The ambivalent attitude of, especially, non-psychotic chronic patients towards psychiatric care may be frustrating and burdensome to professionals. Many of these patients are cared for in non-specialized services, where

Problems in psychiatric care of 'difficult patients': a Delphi-study

NARCIS (Netherlands)

Koekkoek, B.W.; Meijel, B.K.G. van; Schene, A.H.; Hutschemaekers, G.J.M.

2009-01-01

Aims - 'difficult patients' may evoke strong feelings in health professionals. The ambivalent attitude of, especially, non-psychotic chronic patients towards psychiatric care may be frustrating and burdensome to professionals. Many of these patients are cared for in non-specialized services, where

What Makes a Beam Shaping Problem Difficult

International Nuclear Information System (INIS)

Romero, Louis; Dickey, Fred M.

2000-01-01

The authors have discussed the three factors that they believe are the most important in determining the difficulty of a beam shaping problem: scaling, smoothness, and coherence. The arguments have been almost completely based on considering how these factors influence beam shaping lenses that were designed using geometrical optics. However, they believe that these factors control the difficulty of beam shaping problems even if one does not base ones design strategy on geometrical optics. For example, they have shown that a lens designed using geometrical optics will not work well unless β is large. However, they have also shown that if β is small the uncertainty principle shows that it is impossible to do a good job of beam shaping no matter how one designs ones lens

Unstable values: A difficult problem for risk assessment

International Nuclear Information System (INIS)

Fischhoff, B.; Slovic, P.; Lichtenstein, S.

1983-01-01

People with somewhat rudimentary value concepts and those searching for values are compared to one another. In order to solve problems of instability the authors look into and evaluates problems like: psychophysics of concepts of values, definition of the object of the question, influencing the outlook of the persons interviewed, changes in the interviewed persons and sensitivity analysis. (DG) [de

The greenhouse effect and extreme weather

International Nuclear Information System (INIS)

Groenaas, Sigbjoern; Kvamstoe, Nils Gunnar

2002-01-01

The article asserts that an anthropogenic global warming is occurring. This greenhouse effect is expected to cause more occurrences of extreme weather. It is extremely difficult, however, to relate specific weather catastrophes to global warming with certainty, since such extreme weather conditions are rare historically. The subject is controversial. The article also discusses the public debate and the risk of floods

Clinical review: Management of difficult airways

Science.gov (United States)

Langeron, Olivier; Amour, Julien; Vivien, Benoît; Aubrun, Frédéric

2006-01-01

Difficulties or failure in airway management are still important factors in morbidity and mortality related to anesthesia and intensive care. A patent and secure airway is essential to manage anesthetized or critically ill patients. Oxygenation maintenance during tracheal intubation is the cornerstone of difficult airway management and is always emphasized in guidelines. The occurrence of respiratory adverse events has decreased in claims for injuries due to inadequate airway management mainly at induction of anesthesia. Nevertheless, claim reports emphasize that airway emergencies, tracheal extubation and/or recovery of anesthesia phases are still associated with death or brain damage, indicating that additional educational support and management strategies to improve patient safety are required. The present brief review analyses specific problems of airway management related to difficult tracheal intubation and to difficult mask ventilation prediction. The review will focus on basic airway management including preoxygenation, and on some oxygenation and tracheal intubation techniques that may be performed to solve a difficult airway. PMID:17184555

Clinical review: management of difficult airways.

Science.gov (United States)

Langeron, Olivier; Amour, Julien; Vivien, Benoît; Aubrun, Frédéric

2006-01-01

Difficulties or failure in airway management are still important factors in morbidity and mortality related to anesthesia and intensive care. A patent and secure airway is essential to manage anesthetized or critically ill patients. Oxygenation maintenance during tracheal intubation is the cornerstone of difficult airway management and is always emphasized in guidelines. The occurrence of respiratory adverse events has decreased in claims for injuries due to inadequate airway management mainly at induction of anesthesia. Nevertheless, claim reports emphasize that airway emergencies, tracheal extubation and/or recovery of anesthesia phases are still associated with death or brain damage, indicating that additional educational support and management strategies to improve patient safety are required. The present brief review analyses specific problems of airway management related to difficult tracheal intubation and to difficult mask ventilation prediction. The review will focus on basic airway management including preoxygenation, and on some oxygenation and tracheal intubation techniques that may be performed to solve a difficult airway.

Difficult to predict early failure after major lower-extremity amputations

DEFF Research Database (Denmark)

Kristensen, Morten Tange; Holm, Gitte; Gebuhr, Peter

2015-01-01

INTRODUCTION: The successful outcome of a major amputation depends on several factors, including stump wound healing. The purpose of this study was to examine the criteria upon which the index amputation was based and to identify factors associated with early amputation failure after major non......-traumatic lower-extremity amputation. METHODS: We studied a consecutive one-year series of 36 men and 34 women with a median (25-75% quartiles) age of 72 (63-83) years who were treated in an acute orthopaedic ward; 44 below-knee and 26 above-knee amputees of whom 47 had an American Society of Anesthesiologists...... rating above two. Patient characteristics and other factors potentially influencing early amputation failure within 30 days were evaluated. RESULTS: Eleven patients died (16%) and 11 (16%) had a re-amputation at a higher level, whereas four (6%) had a major revision at the same level within 30 days...

The Markov moment problem and extremal problems

CERN Document Server

Kreĭn, M G; Louvish, D

1977-01-01

In this book, an extensive circle of questions originating in the classical work of P. L. Chebyshev and A. A. Markov is considered from the more modern point of view. It is shown how results and methods of the generalized moment problem are interlaced with various questions of the geometry of convex bodies, algebra, and function theory. From this standpoint, the structure of convex and conical hulls of curves is studied in detail and isoperimetric inequalities for convex hulls are established; a theory of orthogonal and quasiorthogonal polynomials is constructed; problems on limiting values of integrals and on least deviating functions (in various metrics) are generalized and solved; problems in approximation theory and interpolation and extrapolation in various function classes (analytic, absolutely monotone, almost periodic, etc.) are solved, as well as certain problems in optimal control of linear objects.

Rules and technical tricks in extremely difficult laparoscopic cholecystectomies

Directory of Open Access Journals (Sweden)

Liviu Drăghici

2017-11-01

Full Text Available We remind you of some technical artifices required in order to resolve difficult cases, such as: antegrade laparoscopic cholecystectomy (LC, subtotal laparoscopic cholecystectomy (SLC and the “stairs” clipping of the cystic duct. Also we acknowledge the closing of the cystic duct. We analyzed the medical records of 15251 laparoscopic cholecystectomies performed during 1994-2015, with emphasis on: surgical technique, conversion rate, hemorrhage, postoperative bile leaking, iatrogenic MBD injuries and mortality. We divided the cases in 5 study groups, group 1 (1994- 2004 N= 5138, group 2 (2005-2015 N= 10113, group 3 (fundus first cholecystectomies, N=2348, group 4 (retrograde cholecystectomies, N=12889 and group 5 (subtotal laparoscopic cholecystectomy-SLC, N=14 which we compared regarding the main parameters. We prefer to perform a “step by step” clipping each time the length of the clip does not cover all the circumference of the cystic duct. This artifices, is a simple laparoscopic gesture easy to perform and has the advantage of avoiding a large excessive and risky laparoscopic dissection in the vicinity of the main biliary duct. More seldom we appeal to the suture of the cystic stump using the intracorporeal knots or a simple stump ligation with an extracorporeal preformed not. We did not encounter any late or early complications following the implementation of this technical laparoscopic artifice. Laborious laparoscopic cholecystectomies performed by a well-trained surgical team ensure the premises of a good performance even while adopting laparoscopic ingenious and difficile gestures that also respect the intraoperatory rules and principals.

Optimization with Extremal Dynamics

International Nuclear Information System (INIS)

Boettcher, Stefan; Percus, Allon G.

2001-01-01

We explore a new general-purpose heuristic for finding high-quality solutions to hard discrete optimization problems. The method, called extremal optimization, is inspired by self-organized criticality, a concept introduced to describe emergent complexity in physical systems. Extremal optimization successively updates extremely undesirable variables of a single suboptimal solution, assigning them new, random values. Large fluctuations ensue, efficiently exploring many local optima. We use extremal optimization to elucidate the phase transition in the 3-coloring problem, and we provide independent confirmation of previously reported extrapolations for the ground-state energy of ±J spin glasses in d=3 and 4

Environmental risk evaluation of difficult substances in USES 2.0

NARCIS (Netherlands)

Beelen P van; ECO

1998-01-01

An inventory is given of the problems which arise when difficult substances are evaluated with the Uniform System for the Evaluation of Substances (USES). It gives an indication about the different classes of chemicals which can give problems in USES. Further, it describes the problems which occur

Study on the effectiveness of Extreme Cold Mist MQL system on turning process of stainless steel AISI 316

Science.gov (United States)

Jamaludin, A. S.; Hosokawa, A.; Furumoto, T.; Koyano, T.; Hashimoto, Y.

2018-03-01

Cutting process of difficult-to-cut material such as stainless steel, generates immensely excessive heat, which is one of the major causes related to shortening tool life and lower quality of surface finish. It is proven that application of cutting fluid during the cutting process of difficult-to-cut material is able to improve the cutting performance, but excessive application of cutting fluid leads to another problem such as increasing processing cost and environmental hazardous pollution of workplace. In the study, Extreme Cold Mist system is designed and tested along with various Minimum Quantity Lubrication (MQL) systems on turning process of stainless steel AISI 316. In the study, it is obtained that, Extreme Cold Mist system is able to reduce cutting force up to 60N and improve the surface roughness of the machined surface significantly.

Risk analysis and solving the nuclear waste siting problem

International Nuclear Information System (INIS)

Inhaber, H.

1993-01-01

In spite of millions of dollars and countless human resources being expended on finding nuclear wastes sites, the search has proved extremely difficult for the nuclear industry. This may be due to the approach followed, rather than inadequacies in research or funding. A new approach to the problem, the reverse Dutch auction, is suggested. It retains some of the useful elements of the present system, but it also adds new ones

Risk analysis and solving the nuclear waste siting problem

Energy Technology Data Exchange (ETDEWEB)

Inhaber, H.

1993-12-01

In spite of millions of dollars and countless human resources being expended on finding nuclear wastes sites, the search has proved extremely difficult for the nuclear industry. This may be due to the approach followed, rather than inadequacies in research or funding. A new approach to the problem, the reverse Dutch auction, is suggested. It retains some of the useful elements of the present system, but it also adds new ones.

Deformation mechanisms in a coal mine roadway in extremely swelling soft rock.

Science.gov (United States)

Li, Qinghai; Shi, Weiping; Yang, Renshu

2016-01-01

The problem of roadway support in swelling soft rock was one of the challenging problems during mining. For most geological conditions, combinations of two or more supporting approaches could meet the requirements of most roadways; however, in extremely swelling soft rock, combined approaches even could not control large deformations. The purpose of this work was to probe the roadway deformation mechanisms in extremely swelling soft rock. Based on the main return air-way in a coal mine, deformation monitoring and geomechanical analysis were conducted, as well as plastic zone mechanical model was analysed. Results indicated that this soft rock was potentially very swelling. When the ground stress acted alone, the support strength needed in situ was not too large and combined supporting approaches could meet this requirement; however, when this potential released, the roadway would undergo permanent deformation. When the loose zone reached 3 m within surrounding rock, remote stress p ∞ and supporting stress P presented a linear relationship. Namely, the greater the swelling stress, the more difficult it would be in roadway supporting. So in this extremely swelling soft rock, a better way to control roadway deformation was to control the releasing of surrounding rock's swelling potential.

Why Is the Overheating Problem Difficult: the Role of Entropy

Science.gov (United States)

Liou, Meng-Sing

2013-01-01

The development of computational fluid dynamics over the last few decades has yielded enormous successes and capabilities being routinely employed today; however there remain some open problems to be properly resolved-some are fundamental in nature and some resolvable by operational changes. These two categories are distinguished and broadly explored previously. One, that belongs to the former, is the so-called overheating problem, especially in rarefying flow. This problem up to date still dogs every method known to the author; a solution to it remains elusive. The study in this paper concludes that: (1) the entropy increase is quantitatively linked to the increase in the temperature increase, (2) it is argued that the overheating is inevitable in the current shock capturing or traditional finite difference framework, and (3) a simple hybrid method is proposed that removes the overheating problem in the rarefying problems, but also retains the property of accurate shock capturing. This remedy (enhancement of current numerical methods) can be included easily in the present Eulerian codes.

Improving extreme-scale problem solving: assessing electronic brainstorming effectiveness in an industrial setting.

Science.gov (United States)

Dornburg, Courtney C; Stevens, Susan M; Hendrickson, Stacey M L; Davidson, George S

2009-08-01

An experiment was conducted to compare the effectiveness of individual versus group electronic brainstorming to address difficult, real-world challenges. Although industrial reliance on electronic communications has become ubiquitous, empirical and theoretical understanding of the bounds of its effectiveness have been limited. Previous research using short-term laboratory experiments have engaged small groups of students in answering questions irrelevant to an industrial setting. The present experiment extends current findings beyond the laboratory to larger groups of real-world employees addressing organization-relevant challenges during the course of 4 days. Employees and contractors at a national laboratory participated, either in a group setting or individually, in an electronic brainstorm to pose solutions to a real-world problem. The data demonstrate that (for this design) individuals perform at least as well as groups in producing quantity of electronic ideas, regardless of brainstorming duration. However, when judged with respect to quality along three dimensions (originality, feasibility, and effectiveness), the individuals significantly (p industrial reliance on electronic problem-solving groups should be tempered, and large nominal groups may be more appropriate corporate problem-solving vehicles.

Methods and scales in soil erosion studies in Spain: problems and perspectives

Energy Technology Data Exchange (ETDEWEB)

Garcia-Ruiz, J. M.

2009-07-01

Soil erosion is a major problem in some areas of Spain. Research groups have studied a variety of aspects of this problem indifferent environments, and at a range of scales using a diversity of methods, from piquettes and rainfall simulation to experimental plots, catchment and large regional areas. This has increased knowledge and identified the main problems: farmland abandonment, badlands erosion, the effects of land use changes, and the role of extreme events and erosion in certain crops (particularly vineyards). However, comparison of results among various research groups has been difficult, posing problems in developing solutions from State and Regional administrators. (Author) 73 refs.

A nuclear-armed Iran: a difficult but not impossible policy problem - Lecture note

International Nuclear Information System (INIS)

Sitt, Bernard

2006-01-01

This lecture note makes an analysis of a report by Barry R. Posen from The Century Foundation (TCF) and entitled: 'A nuclear-armed Iran: a difficult but not impossible policy problem' (28 Dec 2006). In this report, the author believes that diplomacy would be the ideal outcome in handling the nuclear bomb situation in Iran, but containment and deterrence will be effective if diplomacy fails. He challenges the common fears that arise from Iran's potential possession of a bomb: The fear that Iran would use nuclear threats against nonnuclear neighbors; The fear that Iran would use nuclear weapons to annihilate the state of Israel. To ensure effective deterrence, the United States would need to pursue a strategy of coexistence with a nuclear Iran. In order to do so, the US would have to renew its commitment to the security of the Middle East; US involvement would be required to prevent regional proliferation and to ensure the protection of Iran's neighbors. The present Lecture note analyzes and discusses the 4 threats of a nuclear Iran that need to be dissuaded: a risky and more violent foreign policy; the blackmailing of some neighbor countries; the supply of nuclear weapons to non-state actors; and nuclear strikes against Israel despite inevitable retaliatory measures

Technology improves upper extremity rehabilitation.

Science.gov (United States)

Kowalczewski, Jan; Prochazka, Arthur

2011-01-01

Stroke survivors with hemiparesis and spinal cord injury (SCI) survivors with tetraplegia find it difficult or impossible to perform many activities of daily life. There is growing evidence that intensive exercise therapy, especially when supplemented with functional electrical stimulation (FES), can improve upper extremity function, but delivering the treatment can be costly, particularly after recipients leave rehabilitation facilities. Recently, there has been a growing level of interest among researchers and healthcare policymakers to deliver upper extremity treatments to people in their homes using in-home teletherapy (IHT). The few studies that have been carried out so far have encountered a variety of logistical and technical problems, not least the difficulty of conducting properly controlled and blinded protocols that satisfy the requirements of high-level evidence-based research. In most cases, the equipment and communications technology were not designed for individuals with upper extremity disability. It is clear that exercise therapy combined with interventions such as FES, supervised over the Internet, will soon be adopted worldwide in one form or another. Therefore it is timely that researchers, clinicians, and healthcare planners interested in assessing IHT be aware of the pros and cons of the new technology and the factors involved in designing appropriate studies of it. It is crucial to understand the technical barriers, the role of telesupervisors, the motor improvements that participants can reasonably expect and the process of optimizing IHT-exercise therapy protocols to maximize the benefits of the emerging technology. Copyright © 2011 Elsevier B.V. All rights reserved.

Regional anesthesia in difficult airway: The quest for a solution continues.

Science.gov (United States)

Khetarpal, Ranjana; Chatrath, Veena; Dhawan, Akshay; Attri, Joginder Pal

2016-01-01

Difficult airway, a scenario with potentially life threatening outcome, is routinely encountered by an anesthesiologist leaving him with the dilemma of whether to use regional anesthesia (RA) or general anesthesia. Our study aims to look into this problem. The literature search was performed in the Google, PubMed, and Medscape using key words "regional anesthesia, difficult airway, pregnancy, ventilation, intubation, epidural anesthesia, nerve blocks." More than 38 free full articles and books published from the year 1987 to 2014 were retrieved and studied. At first sight, RA may appear to offer an ideal solution as it helps to avoid the problem of difficult airway. However, the possibility of a total spinal block, failed or incomplete RA, local anesthetic toxicity or unforeseen surgical complication may make it imperative that the airway is secured. The correct decision can only be made by the anesthetist when all the relevant clinical information is taken into account. It is also important to ensure that before considering RA in a patient of difficult airway, an anesthesiologist must have a preformulated strategy for intubation.

Case management services for work related upper extremity disorders. Integrating workplace accommodation and problem solving.

Science.gov (United States)

Shaw, W S; Feuerstein, M; Lincoln, A E; Miller, V I; Wood, P M

2001-08-01

A case manager's ability to obtain worksite accommodations and engage workers in active problem solving may improve health and return to work outcomes for clients with work related upper extremity disorders (WRUEDs). This study examines the feasibility of a 2 day training seminar to help nurse case managers identify ergonomic risk factors, provide accommodation, and conduct problem solving skills training with workers' compensation claimants recovering from WRUEDs. Eight procedural steps to this case management approach were identified, translated into a training workshop format, and conveyed to 65 randomly selected case managers. Results indicate moderate to high self ratings of confidence to perform ergonomic assessments (mean = 7.5 of 10) and to provide problem solving skills training (mean = 7.2 of 10) after the seminar. This training format was suitable to experienced case managers and generated a moderate to high level of confidence to use this case management approach.

Game theory and extremal optimization for community detection in complex dynamic networks.

Science.gov (United States)

Lung, Rodica Ioana; Chira, Camelia; Andreica, Anca

2014-01-01

The detection of evolving communities in dynamic complex networks is a challenging problem that recently received attention from the research community. Dynamics clearly add another complexity dimension to the difficult task of community detection. Methods should be able to detect changes in the network structure and produce a set of community structures corresponding to different timestamps and reflecting the evolution in time of network data. We propose a novel approach based on game theory elements and extremal optimization to address dynamic communities detection. Thus, the problem is formulated as a mathematical game in which nodes take the role of players that seek to choose a community that maximizes their profit viewed as a fitness function. Numerical results obtained for both synthetic and real-world networks illustrate the competitive performance of this game theoretical approach.

An Improved Real-Coded Population-Based Extremal Optimization Method for Continuous Unconstrained Optimization Problems

Directory of Open Access Journals (Sweden)

Guo-Qiang Zeng

2014-01-01

Full Text Available As a novel evolutionary optimization method, extremal optimization (EO has been successfully applied to a variety of combinatorial optimization problems. However, the applications of EO in continuous optimization problems are relatively rare. This paper proposes an improved real-coded population-based EO method (IRPEO for continuous unconstrained optimization problems. The key operations of IRPEO include generation of real-coded random initial population, evaluation of individual and population fitness, selection of bad elements according to power-law probability distribution, generation of new population based on uniform random mutation, and updating the population by accepting the new population unconditionally. The experimental results on 10 benchmark test functions with the dimension N=30 have shown that IRPEO is competitive or even better than the recently reported various genetic algorithm (GA versions with different mutation operations in terms of simplicity, effectiveness, and efficiency. Furthermore, the superiority of IRPEO to other evolutionary algorithms such as original population-based EO, particle swarm optimization (PSO, and the hybrid PSO-EO is also demonstrated by the experimental results on some benchmark functions.

A child with a difficult airway: what do I do next?

Science.gov (United States)

Engelhardt, Thomas; Weiss, Markus

2012-06-01

Difficulties in pediatric airway management are common and continue to result in significant morbidity and mortality. This review reports on current concepts in approaching a child with a difficult airway. Routine airway management in healthy children with normal airways is simple in experienced hands. Mask ventilation (oxygenation) is always possible and tracheal intubation normally simple. However, transient hypoxia is common in these children usually due to unexpected anatomical and functional airway problems or failure to ventilate during rapid sequence induction. Anatomical airway problems (upper airway collapse and adenoid hypertrophy) and functional airway problems (laryngospasm, bronchospasm, insufficient depth of anesthesia and muscle rigidity, gastric hyperinflation, and alveolar collapse) require urgent recognition and treatment algorithms due to insufficient oxygen reserves. Early muscle paralysis and epinephrine administration aids resolution of these functional airway obstructions. Children with an 'impaired' normal (foreign body, allergy, and inflammation) or an expected difficult (scars, tumors, and congenital) airway require careful planning and expertise. Training in the recognition and management of these different situations as well as a suitably equipped anesthesia workstation and trained personnel are essential. The healthy child with an unexpected airway problem requires clear strategies. The 'impaired' normal pediatric airway may be handled by anesthetists experienced with children, whereas the expected difficult pediatric airway requires dedicated pediatric anesthesia specialist care and should only be managed in specialized centers.

Piecewise-linear and bilinear approaches to nonlinear differential equations approximation problem of computational structural mechanics

OpenAIRE

Leibov Roman

2017-01-01

This paper presents a bilinear approach to nonlinear differential equations system approximation problem. Sometimes the nonlinear differential equations right-hand sides linearization is extremely difficult or even impossible. Then piecewise-linear approximation of nonlinear differential equations can be used. The bilinear differential equations allow to improve piecewise-linear differential equations behavior and reduce errors on the border of different linear differential equations systems ...

Estimation of extreme risk regions under multivariate regular variation

NARCIS (Netherlands)

Cai, J.; Einmahl, J.H.J.; de Haan, L.F.M.

2011-01-01

When considering d possibly dependent random variables, one is often interested in extreme risk regions, with very small probability p. We consider risk regions of the form {z ∈ Rd : f (z) ≤ β}, where f is the joint density and β a small number. Estimation of such an extreme risk region is difficult

Discussion of difficult problems of early diagnosis of pancreatic cancer

Directory of Open Access Journals (Sweden)

GUO Xiaozhong

2014-08-01

Full Text Available Pancreatic cancer is a common malignant neoplasm of the pancreas with an extremely high mortality. Currently, the early diagnosis of pancreatic cancer is still not ideal. Attention should be paid to some clinical warning symptoms, such as unexplained abdominal and back pain, jaundice, and unexpected diabetes. Additionally, the combined use of CA19-9, CEA, and other tumor markers, the attention to biochemical indicators, the detection of mutation in KAI1 or p53 gene, and the exploration of the value of miRNA in clinical diagnosis are of great significance. On the other hand, ultrasound, CT, MRCP, ERCP, PET-CT, and other imaging methods, as well as effective collection of cytology specimens, should be performed. Thus, there is hope for the early diagnosis of pancreatic cancer.

Evolution caused by extreme events.

Science.gov (United States)

Grant, Peter R; Grant, B Rosemary; Huey, Raymond B; Johnson, Marc T J; Knoll, Andrew H; Schmitt, Johanna

2017-06-19

Extreme events can be a major driver of evolutionary change over geological and contemporary timescales. Outstanding examples are evolutionary diversification following mass extinctions caused by extreme volcanism or asteroid impact. The evolution of organisms in contemporary time is typically viewed as a gradual and incremental process that results from genetic change, environmental perturbation or both. However, contemporary environments occasionally experience strong perturbations such as heat waves, floods, hurricanes, droughts and pest outbreaks. These extreme events set up strong selection pressures on organisms, and are small-scale analogues of the dramatic changes documented in the fossil record. Because extreme events are rare, almost by definition, they are difficult to study. So far most attention has been given to their ecological rather than to their evolutionary consequences. We review several case studies of contemporary evolution in response to two types of extreme environmental perturbations, episodic (pulse) or prolonged (press). Evolution is most likely to occur when extreme events alter community composition. We encourage investigators to be prepared for evolutionary change in response to rare events during long-term field studies.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events'. © 2017 The Author(s).

Atomic collisions under extreme conditions in space

International Nuclear Information System (INIS)

Itikawa, Yukikazu

1987-01-01

In space, atoms and molecules are often placed under the extreme conditions which are very difficult to be realized on Earth. For instance, extremely hot and dense plasmas are found in and around various stellar objects (e.g., neutron stars) on one hand and extremely cold and diffuse gases prevail in interstellar space on the other. There is so strong a magnetic field that electron clouds in atoms and molecules are distorted. The study of atomic collisions under the extreme conditions is not only helpful in understanding the astrophysical environment but also reveals new aspects of the physics of atoms and molecules. This paper is an invitation to the study. (References are not exhaustive but only provide a clue with which more details can be found.) (author)

New Dandelion Algorithm Optimizes Extreme Learning Machine for Biomedical Classification Problems

Directory of Open Access Journals (Sweden)

Xiguang Li

2017-01-01

Full Text Available Inspired by the behavior of dandelion sowing, a new novel swarm intelligence algorithm, namely, dandelion algorithm (DA, is proposed for global optimization of complex functions in this paper. In DA, the dandelion population will be divided into two subpopulations, and different subpopulations will undergo different sowing behaviors. Moreover, another sowing method is designed to jump out of local optimum. In order to demonstrate the validation of DA, we compare the proposed algorithm with other existing algorithms, including bat algorithm, particle swarm optimization, and enhanced fireworks algorithm. Simulations show that the proposed algorithm seems much superior to other algorithms. At the same time, the proposed algorithm can be applied to optimize extreme learning machine (ELM for biomedical classification problems, and the effect is considerable. At last, we use different fusion methods to form different fusion classifiers, and the fusion classifiers can achieve higher accuracy and better stability to some extent.

Parenteral nutrition in patients with inborn errors of metabolism - a therapeutic problem.

Science.gov (United States)

Kaluzny, L; Szczepanik, M; Siwinska-Mrozek, Z; Borkowska-Klos, M; Cichy, W; Walkowiak, J

2014-06-01

Parenteral nutrition is now a standard part of supportive treatment in pediatric departments. We describe four cases in which parenteral nutrition was extremely difficult due to coincidence with inborn errors of metabolism. The first two cases was fatty acid beta-oxidation disorders associated with necrotizing enterocolitis and congenital heart disease. Thus, limitations of intravenous lipid intake made it difficult to maintain a good nutritional status. The third case was phenylketonuria associated with a facial region tumour (rhabdomyosarcoma), in which parenteral nutrition was complicated because of a high phenylalanine content in the amino acid formulas for parenteral nutrition. The fourth patient was a child with late-diagnosed tyrosinemia type 1, complicated with encephalopathy - during intensive care treatment the patient needed nutritional support, including parenteral nutrition - we observed amino acid formula problems similar to those in the phenylketonuria patient. Parenteral nutrition in children with inborn errors of metabolism is a rare, but very important therapeutic problem. Total parenteral nutrition formulas are not prepared for this group of diseases.

Distant Galaxy Clusters Hosting Extreme Central Galaxies

Science.gov (United States)

McDonald, Michael

2014-09-01

The recently-discovered Phoenix cluster harbors the most star-forming central cluster galaxy of any cluster in the known Universe, by nearly a factor of 10. This extreme system appears to be fulfilling early cooling flow predictions, although the lack of similar systems makes any interpretation difficult. In an attempt to find other "Phoenix-like" clusters, we have cross-correlated archival all-sky surveys (in which Phoenix was detected) and isolated 4 similarly-extreme systems which are also coincident in position and redshift with an overdensity of red galaxies. We propose here to obtain Chandra observations of these extreme, Phoenix-like systems, in order to confirm them as relaxed, rapidly-cooling galaxy clusters.

An Improved Crow Search Algorithm Applied to Energy Problems

Directory of Open Access Journals (Sweden)

Primitivo Díaz

2018-03-01

Full Text Available The efficient use of energy in electrical systems has become a relevant topic due to its environmental impact. Parameter identification in induction motors and capacitor allocation in distribution networks are two representative problems that have strong implications in the massive use of energy. From an optimization perspective, both problems are considered extremely complex due to their non-linearity, discontinuity, and high multi-modality. These characteristics make difficult to solve them by using standard optimization techniques. On the other hand, metaheuristic methods have been widely used as alternative optimization algorithms to solve complex engineering problems. The Crow Search Algorithm (CSA is a recent metaheuristic method based on the intelligent group behavior of crows. Although CSA presents interesting characteristics, its search strategy presents great difficulties when it faces high multi-modal formulations. In this paper, an improved version of the CSA method is presented to solve complex optimization problems of energy. In the new algorithm, two features of the original CSA are modified: (I the awareness probability (AP and (II the random perturbation. With such adaptations, the new approach preserves solution diversity and improves the convergence to difficult high multi-modal optima. In order to evaluate its performance, the proposed algorithm has been tested in a set of four optimization problems which involve induction motors and distribution networks. The results demonstrate the high performance of the proposed method when it is compared with other popular approaches.

Past and future changes in extreme sea levels and waves

Digital Repository Service at National Institute of Oceanography (India)

Lawe, J.A.; Woodworth, P.L.; Knutson, T.; McDonald, R.E.; Mclnnes, K.L.; Woth, K.; Von Storch, H.; Wolf, J.; Swail, V.; Bernier, N.B.; Gulev, S.; Horsburgh, K.J.; Unnikrishnan, A.S.; Hunter, J.R.; Weisse, R.

of Extreme Sea Level 11.3.1 An Introduction to Storms Both mid-latitude and tropical storms are associated with extremes of sea level. Storm surges are generated by low atmospheric pressure and intense winds over the ocean. The latter also cause high wave... timescales, extremes and mean-sea-level change are both major factors in determining coastal evolution including the development of coastal ecosystems. It will be seen below that, although it is difficult to determine how mean sea level has changed...

Extreme-Scale Bayesian Inference for Uncertainty Quantification of Complex Simulations

Energy Technology Data Exchange (ETDEWEB)

Biros, George [Univ. of Texas, Austin, TX (United States)

2018-01-12

Uncertainty quantification (UQ)—that is, quantifying uncertainties in complex mathematical models and their large-scale computational implementations—is widely viewed as one of the outstanding challenges facing the field of CS&E over the coming decade. The EUREKA project set to address the most difficult class of UQ problems: those for which both the underlying PDE model as well as the uncertain parameters are of extreme scale. In the project we worked on these extreme-scale challenges in the following four areas: 1. Scalable parallel algorithms for sampling and characterizing the posterior distribution that exploit the structure of the underlying PDEs and parameter-to-observable map. These include structure-exploiting versions of the randomized maximum likelihood method, which aims to overcome the intractability of employing conventional MCMC methods for solving extreme-scale Bayesian inversion problems by appealing to and adapting ideas from large-scale PDE-constrained optimization, which have been very successful at exploring high-dimensional spaces. 2. Scalable parallel algorithms for construction of prior and likelihood functions based on learning methods and non-parametric density estimation. Constructing problem-specific priors remains a critical challenge in Bayesian inference, and more so in high dimensions. Another challenge is construction of likelihood functions that capture unmodeled couplings between observations and parameters. We will create parallel algorithms for non-parametric density estimation using high dimensional N-body methods and combine them with supervised learning techniques for the construction of priors and likelihood functions. 3. Bayesian inadequacy models, which augment physics models with stochastic models that represent their imperfections. The success of the Bayesian inference framework depends on the ability to represent the uncertainty due to imperfections of the mathematical model of the phenomena of interest. This is a

Performance testing of extremity dosimeters, Study 2

International Nuclear Information System (INIS)

Harty, R.; Reece, W.D.; Hooker, C.D.

1990-04-01

The Health Physics Society Standards Committee (HPSSC) Working Group on Performance Testing of Extremity Dosimeters has issued a draft of a proposed standard for extremity dosimeters. The draft standard proposes methods to be used for testing dosimetry systems that determine occupational radiation dose to the extremities and the performance criterion used to determine compliance with the standard. Pacific Northwest Laboratory (PNL) has conducted two separate evaluations of the performance of extremity dosimeter processors to determine the appropriateness of the draft standard, as well as to obtain information regarding the performance of extremity dosimeters. Based on the information obtained during the facility visits and the results obtained from the performance testing, it was recommended that changes be made to ensure that the draft standard is appropriate for extremity dosimeters. The changes include: subdividing the mixture category and the beta particle category; eliminating the neutron category until appropriate flux-to-dose equivalent conversion factors are derived; and changing the tolerance level for the performance criterion to provide consistency with the performance criterion for whole body dosimeters, and to avoid making the draft standard overly difficult for processors of extremity dosimeters to pass. 20 refs., 10 figs., 6 tabs

Extreme Wind, Rain, Storm Surge, and Flooding: Why Hurricane Impacts are Difficult to Forecast?

Science.gov (United States)

Chen, S. S.

2017-12-01

The 2017 hurricane season is estimated as one of the costliest in the U.S. history. The damage and devastation caused by Hurricane Harvey in Houston, Irma in Florida, and Maria in Puerto Rico are distinctly different in nature. The complexity of hurricane impacts from extreme wind, rain, storm surge, and flooding presents a major challenge in hurricane forecasting. A detailed comparison of the storm impacts from Harvey, Irma, and Maria will be presented using observations and state-of-the-art new generation coupled atmosphere-wave-ocean hurricane forecast model. The author will also provide an overview on what we can expect in terms of advancement in science and technology that can help improve hurricane impact forecast in the near future.

Distraction during learning with hypermedia: Difficult tasks help to keep task goals on track

Directory of Open Access Journals (Sweden)

Katharina eScheiter

2014-03-01

Full Text Available In educational hypermedia environments, students are often confronted with potential sources of distraction arising from additional information that, albeit interesting, is unrelated to their current task goal. The paper investigates the conditions under which distraction occurs and hampers performance. Based on theories of volitional action control it was hypothesized that interesting information, especially if related to a pending goal, would interfere with task performance only when working on easy, but not on difficult tasks. In Experiment 1, 66 students learned about probability theory using worked examples and solved corresponding test problems, whose task difficulty was manipulated. As a second factor, the presence of interesting information unrelated to the primary task was varied. Results showed that students solved more easy than difficult probability problems correctly. However, the presence of interesting, but task-irrelevant information did not interfere with performance. In Experiment 2, 68 students again engaged in example-based learning and problem solving in the presence of task-irrelevant information. Problem-solving difficulty was varied as a first factor. Additionally, the presence of a pending goal related to the task-irrelevant information was manipulated. As expected, problem-solving performance declined when a pending goal was present during working on easy problems, whereas no interference was observed for difficult problems. Moreover, the presence of a pending goal reduced the time on task-relevant information and increased the time on task-irrelevant information while working on easy tasks. However, as revealed by mediation analyses these changes in overt information processing behavior did not explain the decline in problem-solving performance. As an alternative explanation it is suggested that goal conflicts resulting from pending goals claim cognitive resources, which are then no longer available for learning and

Lymphoscintigraphy of the lower extremity

International Nuclear Information System (INIS)

Abbasi, N.Z.

1990-01-01

Fifty one lower extremities of 26 normal healthy volunteers and 26 extremities of 13 patients with oedema have been studied. Dynamic quantitative lymphoscintigraphy using 99Tc-m antimony sulphide colloid during passive exercise as well as before and after active exercise was performed. parameters of lymphatic function including percentage of radioactivity cleared from the injection site, the percentage uptake by the inguinal lymph nodes, the time of arrival of activity at the regional lymph nodes and the lymphatic reserve index have been evaluated. The percentage clearance of activity from the injection site was found technically difficult to standardize and proved to be an unreliable parameter of lymphatic function. However, the quantitation of nodal uptake, the lymphatic transit time and the lymphatic reserve capacity accurately depicted the lymphatic functional status of an individual. The physiologic parameters of lymphatic function of the contralateral lower extremities were compared and a physiologic difference in the lymphatic capacity of the two limbs was scintigraphically documented. (author)

A compliant mechanism for inspecting extremely confined spaces

Science.gov (United States)

Mascareñas, David; Moreu, Fernando; Cantu, Precious; Shields, Daniel; Wadden, Jack; El Hadedy, Mohamed; Farrar, Charles

2017-11-01

We present a novel, compliant mechanism that provides the capability to navigate extremely confined spaces for the purpose of infrastructure inspection. Extremely confined spaces are commonly encountered during infrastructure inspection. Examples of such spaces can include pipes, conduits, and ventilation ducts. Often these infrastructure features go uninspected simply because there is no viable way to access their interior. In addition, it is not uncommon for extremely confined spaces to possess a maze-like architecture that must be selectively navigated in order to properly perform an inspection. Efforts by the imaging sensor community have resulted in the development of imaging sensors on the millimeter length scale. Due to their compact size, they are able to inspect many extremely confined spaces of interest, however, the means to deliver these sensors to the proper location to obtain the desired images are lacking. To address this problem, we draw inspiration from the field of endoscopic surgery. Specifically we consider the work that has already been done to create long flexible needles that are capable of being steered through the human body. These devices are typically referred to as ‘steerable needles.’ Steerable needle technology is not directly applicable to the problem of navigating maze-like arrangements of extremely confined spaces, but it does provide guidance on how this problem should be approached. Specifically, the super-elastic nitinol tubing material that allows steerable needles to operate is also appropriate for the problem of navigating maze-like arrangements of extremely confined spaces. Furthermore, the portion of the mechanism that enters the extremely confined space is completely mechanical in nature. The mechanical nature of the device is an advantage when the extremely confined space features environmental hazards such as radiation that could degrade an electromechanically operated mechanism. Here, we present a compliant mechanism

Extremal graph theory

CERN Document Server

Bollobas, Bela

2004-01-01

The ever-expanding field of extremal graph theory encompasses a diverse array of problem-solving methods, including applications to economics, computer science, and optimization theory. This volume, based on a series of lectures delivered to graduate students at the University of Cambridge, presents a concise yet comprehensive treatment of extremal graph theory.Unlike most graph theory treatises, this text features complete proofs for almost all of its results. Further insights into theory are provided by the numerous exercises of varying degrees of difficulty that accompany each chapter. A

When Your Child Is Difficult: Solve Your Toughest Child-Raising Problems with a Four-Step Plan That Works.

Science.gov (United States)

Silberman, Mel

Written for parents, this book discusses four steps for dealing with children's difficult behavior. The book is divided into two parts. Part 1, "The Building Blocks," discusses baseline perspectives parents need to establish in order to effectively deal with difficult behavior. Topics covered include: (1) parents' dual roles as caregivers and…

Why do people buy dogs with potential welfare problems related to extreme conformation and inherited disease? A representative study of Danish owners of four small dog breeds

OpenAIRE

Sand?e, P.; Kondrup, S. V.; Bennett, P. C.; Forkman, B.; Meyer, I; Proschowsky, H. F.; Serpell, J. A.; Lund, T. B.

2017-01-01

number of dog breeds suffer from welfare problems due to extreme phenotypes and high levels of inherited diseases but the popularity of such breeds is not declining. Using a survey of owners of two popular breeds with extreme physical features (French Bulldog and Chihuahua), one with a high load of inherited diseases not directly related to conformation (Cavalier King Charles Spaniel), and one representing the same size range but without extreme conformation and with the same level of disease...

The attitudes of neonatal nurses towards extremely preterm infants.

Science.gov (United States)

Gallagher, Katie; Marlow, Neil; Edgley, Alison; Porock, Davina

2012-08-01

The paper is a report of a study of the attitudes of neonatal nurses towards extremely preterm infants. Alongside advancing survival at extremely preterm gestational ages, ethical debates concerning the provision of invasive care have proliferated in light of the high morbidity. Despite nurses being the healthcare professionals who work closest with the infant and their family, their potential influence is usually ignored when determining how parents come to decisions about future care for their extremely premature infant. A Q methodology was employed to explore the attitudes of neonatal nurses towards caring for extremely preterm infants. Data were collected between 2007 and 2008 and analysed using PQMethod and Card Content Analysis. Thirty-six nurses from six neonatal units in the United Kingdom participated. Although there was consensus around the professional role of the nurse, when faced with the complexities of neonatal nursing three distinguishing factors emerged: the importance of parental choice in decision-making, the belief that technology should be used to assess response to treatment, and the belief that healthcare professionals should undertake difficult decisions. Neonatal nurses report unexpected difficulties in upholding their professionally defined role through highly complex and ever varied decision-making processes. Recognition of individual attitudes to the care of extremely preterm infants and the role of the family in the face of difficult decisions should facilitate more open communication between the nurse and the parents and improve the experience of both the nurse and the family during these emotional situations. © 2011 Blackwell Publishing Ltd.

Conflict Management: Difficult Conversations with Difficult People

OpenAIRE

Overton, Amy R.; Lowry, Ann C.

2013-01-01

Conflict occurs frequently in any workplace; health care is not an exception. The negative consequences include dysfunctional team work, decreased patient satisfaction, and increased employee turnover. Research demonstrates that training in conflict resolution skills can result in improved teamwork, productivity, and patient and employee satisfaction. Strategies to address a disruptive physician, a particularly difficult conflict situation in healthcare, are addressed.

Conflict management: difficult conversations with difficult people.

Science.gov (United States)

Overton, Amy R; Lowry, Ann C

2013-12-01

Conflict occurs frequently in any workplace; health care is not an exception. The negative consequences include dysfunctional team work, decreased patient satisfaction, and increased employee turnover. Research demonstrates that training in conflict resolution skills can result in improved teamwork, productivity, and patient and employee satisfaction. Strategies to address a disruptive physician, a particularly difficult conflict situation in healthcare, are addressed.

Computational discovery of extremal microstructure families

Science.gov (United States)

Chen, Desai; Skouras, Mélina; Zhu, Bo; Matusik, Wojciech

2018-01-01

Modern fabrication techniques, such as additive manufacturing, can be used to create materials with complex custom internal structures. These engineered materials exhibit a much broader range of bulk properties than their base materials and are typically referred to as metamaterials or microstructures. Although metamaterials with extraordinary properties have many applications, designing them is very difficult and is generally done by hand. We propose a computational approach to discover families of microstructures with extremal macroscale properties automatically. Using efficient simulation and sampling techniques, we compute the space of mechanical properties covered by physically realizable microstructures. Our system then clusters microstructures with common topologies into families. Parameterized templates are eventually extracted from families to generate new microstructure designs. We demonstrate these capabilities on the computational design of mechanical metamaterials and present five auxetic microstructure families with extremal elastic material properties. Our study opens the way for the completely automated discovery of extremal microstructures across multiple domains of physics, including applications reliant on thermal, electrical, and magnetic properties. PMID:29376124

Difficult behaviors in the emergency department: a cohort study of housed, homeless and alcohol dependent individuals.

Directory of Open Access Journals (Sweden)

Tomislav Svoboda

Full Text Available This study contrasted annual rates of difficult behaviours in emergency departments among cohorts of individuals who were homeless and low-income housed and examined predictors of these events.Interviews in 1999 with men who were chronically homeless with drinking problems (CHDP (n = 50, men from the general homeless population (GH (n = 61, and men residing in low-income housing (LIH (n = 58 were linked to catchment area emergency department records (n = 2817 from 1994 to 1999. Interview and hospital data were linked to measures of difficult behaviours.Among the CHDP group, annual rates of visits with difficult behaviours were 5.46; this was 13.4 (95% CI 10.3-16.5 and 14.3 (95% CI 11.2-17.3 times higher than the GH and LIH groups. Difficult behaviour incidents included physical violence, verbal abuse, uncooperativeness, drug seeking, difficult histories and security involvement. Difficult behaviours made up 57.54% (95% CI 55.43-59.65%, 24% (95% CI 19-29%, and 20% (95% CI 16-24% of CHDP, GH and LIH visits. Among GH and LIH groups, 87% to 95% were never involved in verbal abuse or violence. Intoxication increased all difficult behaviours while decreasing drug seeking and leaving without being seen. Verbal abuse and violence were less likely among those housed, with odds ratios of 0.24 (0.08, 0.72 and 0.32 (0.15, 0.69, respectively.Violence and difficult behaviours are much higher among chronically homeless men with drinking problems than general homeless and low-income housed populations. They are concentrated among subgroups of individuals. Intoxication is the strongest predictor of difficult behaviour incidents.

Infant difficult behaviors in the context of perinatal biomedical conditions and early child environment

Directory of Open Access Journals (Sweden)

Sirvinskiene Giedre

2012-04-01

Full Text Available Abstract Background Problems experienced within the first year of an infant's life can be precursors of later mental health conditions. The purpose of this study was to examine the frequency and continuity of difficult behaviors in infants at 3 and 6 months of age and the associations of these difficulties with biomedical and psychosocial factors. Methods This study was a part of an ongoing prospective birth-cohort study. Study participants were 189 uniparous mothers and their full-term newborns. The index of infant difficult behavior was constructed. This index was then associated with the following factors: delivery mode, newborn function after birth, maternal emotional well-being, risk behavior, subjective evaluation of the quality of the relationship of the couple, and attitudes toward infant-rearing. Results Common difficult behaviors, including crying, sleeping and eating problems, were characteristic for 30.2% of 3 month old and for 22.2% of 6 month old full-term infants. The expression of infant difficult behaviors at the age of 3 months increased the likelihood of the expression of these difficulties at 6 months by more than 5 times. Factors including younger maternal age, poor prenatal and postnatal emotional well-being, prenatal alcohol consumption, low satisfaction with the couple's relationship before pregnancy, and deficiency of infant-centered maternal attitudes towards infant-rearing increased the likelihood of difficult behaviors in infants at the age of 3 months. Low maternal satisfaction with the relationship of the couple before pregnancy, negative emotional reactions of both parents toward pregnancy (as reported by the mother and the deficiency of an infant-centered maternal attitude towards infant-rearing increased the likelihood of infant difficult behaviors continuing between the ages of 3 to 6 months. Perinatal biomedical conditions were not related to the difficult behaviors in infants. Conclusions Our study suggests

The year 2000 problem as seen by manufacturers; Das Jahr-2000-Problem in deutschen Kernkraftwerken. Aus der Sicht der Hersteller

Energy Technology Data Exchange (ETDEWEB)

Graf, A. [Siemens AG, Erlangen (Germany). Bereich KWU

1999-11-01

The Y2K problem has many facets due mainly to two reasons: The extremely wide use of microcomputers, and the complexity of automation in modern industrial plants. For the past two years, Siemens AG has been checking the Y2K conformity of its products. The result of these investigations is this: All automation equipment, almost without exception, is in conformity with the year 2000 requirements as it works without the date function causing the errors. A few occasional malfunctions were discovered in older computer-supported operating and monitoring stations and in process computer applications. However, malfunctions are not going to cause failures of the system but only make its use more difficult. (orig.) [German] Ursache des Jahr-2000-Problems ist die Unfaehigkeit gewisser aelterer Software, das Jahresdatum 2000 beim Uebergang der letzten beiden Ziffern von '99' auf '00' richtig zu verarbeiten. Potenziell betroffen sind alle Geraete und Systeme, die in irgendeiner Form Rechner oder Mikrorechner enthalten. Das Jahr-2000-Problem ist sehr vielschichtig. Dies resultiert im Wesentlichen aus zwei Gruenden: Der extrem weiten Verbreitung von Mikrorechnern und der Komplexitaet der Automatisierung moderner Industrieanlagen. Die Siemens AG ueberprueft seit zwei Jahren die 2000-Jahr-Konformitaet ihrer Produkte. Ergebnis der Untersuchungen ist: Automatisierungsgeraete sind fast ausnahmslos Jahr-2000 konform, da sie ohne die fehlerverursachenden Datumsfunktionen auskommen. Vereinzelte Fehlfunktionen wurden in aelteren rechnergestuetzten Bedien- und Beobachtungssystemen sowie in Prozessrechneranwendungen gefunden. Fehlfunktionen fuehren jedoch meist nicht zum Versagen des Systems, sondern erschweren nur dessen Nutzung. In den sicherheitsrelevanten Bereichen der Kernkraftwerke werden ausschliesslich die vom Jahr-2000-Problem nicht betroffenen Automatisierungsgeraete eingesetzt. (orig.)

Review of heat transfer problems associated with magnetically-confined fusion reactor concepts

International Nuclear Information System (INIS)

Hoffman, M.A.; Werner, R.W.; Carlson, G.A.; Cornish, D.N.

1976-01-01

Conceptual design studies of possible fusion reactor configurations have revealed a host of interesting and sometimes extremely difficult heat transfer problems. The general requirements imposed on the coolant system for heat removal of the thermonuclear power from the reactor are discussed. In particular, the constraints imposed by the fusion plasma, neutronics, structure and magnetic field environment are described with emphasis on those aspects which are unusual or unique to fusion reactors. Then the particular heat transfer characteristics of various possible coolants including lithium, flibe, boiling alkali metals, and helium are discussed in the context of these general fusion reactor requirements. Some specific areas where further experimental and/or theoretical work is necessary are listed for each coolant along with references to the pertinent research already accomplished. Specialized heat transfer problems of the plasma injection and removal systems are also described. Finally, the challenging heat transfer problems associated with the superconducting magnets are reviewed, and once again some of the key unsolved heat transfer problems are enumerated

The "difficult" patient reconceived: an expanded moral mandate for clinical ethics.

Science.gov (United States)

Fiester, Autumn

2012-01-01

Between 15 and 60% of patients are considered "difficult" by their treating physicians. Patient psychiatric pathology is the conventional explanation for why patients are deemed "difficult." But the prevalence of the problem suggests the possibility of a less pathological cause. I argue that the phenomenon can be better explained as a response to problematic interactions related to health care delivery. If there are grounds to reconceive the "difficult" patient as reacting to the perception of ill treatment, then there is an ethical obligation to address this perception of harm. Resolution of such conflicts currently lies with the provider and patient. But the ethical stakes place these conflicts into the province of the ethics consult service. As the resource for addressing ethical dilemmas, there is a moral mandate to offer assistance in the resolution of these ethically charged conflicts that is no less pressing than the more familiar terrain of clinical ethics consultation.

Soft tissue masses of extremities: MR findings

Energy Technology Data Exchange (ETDEWEB)

Son, Seok Hyun; Yang, Seoung Oh; Choi, Jong Chul; Park, Byeong Ho; Lee, Ki Nam; Choi, Sun Seob; Chung, Duck Hwan [Dong-A University College of Medicine, Pusan (Korea, Republic of)

1993-11-15

To evaluate MR findings of soft tissue masses in extremities and to find the helpful findings of distinguish benignity from malignancy, 28 soft tissue masses (22 benign and 6 malignant) in extremities were reviewed. TI-weighted, proton density, T2-weighted and Gd-DTPA enhanced images were obtained. MR images allowed a specific diagnosis in large number of benign masses, such as hemangioma(8/9), lipoma(2/2), angiolipoma(1/1), epidermoid cyst(2/2), myositis ossificans(1/1), synovial chondromatosis(1/1) and pigmented villonodular synovitis(1/2). Specific diagnosis was difficult in the rest of the masses including malignancy. However, inhomogeneous signal intensities with necrosis and inhomogeneous enhancement may suggest malignant masses.

Extremism from the perspective of a system approach

Directory of Open Access Journals (Sweden)

Zinchenko, Yury P.

2014-03-01

Full Text Available Extremism is seen as a complex, multilevel, and multicomponent phenomenon. The problems of modern science in understanding extremism are revealed. The following bases of extremism as a system phenomenon are singled out: social factors, latent extremism, and extremist acts. It is demonstrated that a system approach makes it possible to shape a notion of a subject as a system, to identify patterns of the manifestations of the given phenomenon, and to translate them into concrete practices.

An anatomy of countertransference: staff reactions to difficult psychiatric hospital patients.

Science.gov (United States)

Colson, D B; Allen, J G; Coyne, L; Dexter, N; Jehl, N; Mayer, C A; Spohn, H

1986-09-01

Countertransference among hospital staff was investigated as part of ongoing research on difficult-to-treat psychiatric hospital patients. Staff's ratings of their emotional reactions to 127 patients on long-term units were analyzed by factor analysis, and the resulting factors were correlated by discipline with patient problem behaviors. Among the conclusions were that different forms of psychopathology elicit characteristic patterns of emotional reaction from staff; that some dimensions of psychopathology, particularly suicidal-depressed behavior and violence-agitation, elicit different emotional reactions among different disciplines, thus laying the groundwork for division among staff; and that the more difficult the process of hospital treatment, the more likely staff will experience a variety of emotions.

Maxillofacial trauma patient: coping with the difficult airway

Directory of Open Access Journals (Sweden)

Barak Michal

2009-05-01

Full Text Available Abstract Establishing a secure airway in a trauma patient is one of the primary essentials of treatment. Any flaw in airway management may lead to grave morbidity and mortality. Maxillofacial trauma presents a complex problem with regard to the patient's airway. By definition, the injury compromises the patient's airway and it is, therefore, must be protected. In most cases, the patient undergoes surgery for maxillofacial trauma or for other, more severe, life-threatening injuries, and securing the airway is the first step in the introduction of general anaesthesia. In such patients, we anticipate difficult endotracheal intubation and, often, also difficult mask ventilation. In addition, the patient is usually regarded as having a "full stomach" and has not been cleared of a C-spine injury, which may complicate airway management furthermore. The time available to accomplish the task is short and the patient's condition may deteriorate rapidly. Both decision-making and performance are impaired in such circumstances. In this review, we discuss the complexity of the situation and present a treatment approach.

Identifying barriers to recovery from work related upper extremity disorders: use of a collaborative problem solving technique.

Science.gov (United States)

Shaw, William S; Feuerstein, Michael; Miller, Virginia I; Wood, Patricia M

2003-08-01

Improving health and work outcomes for individuals with work related upper extremity disorders (WRUEDs) may require a broad assessment of potential return to work barriers by engaging workers in collaborative problem solving. In this study, half of all nurse case managers from a large workers' compensation system were randomly selected and invited to participate in a randomized, controlled trial of an integrated case management (ICM) approach for WRUEDs. The focus of ICM was problem solving skills training and workplace accommodation. Volunteer nurses attended a 2 day ICM training workshop including instruction in a 6 step process to engage clients in problem solving to overcome barriers to recovery. A chart review of WRUED case management reports (n = 70) during the following 2 years was conducted to extract case managers' reports of barriers to recovery and return to work. Case managers documented from 0 to 21 barriers per case (M = 6.24, SD = 4.02) within 5 domains: signs and symptoms (36%), work environment (27%), medical care (13%), functional limitations (12%), and coping (12%). Compared with case managers who did not receive the training (n = 67), workshop participants identified more barriers related to signs and symptoms, work environment, functional limitations, and coping (p Problem solving skills training may help focus case management services on the most salient recovery factors affecting return to work.

Sexuality in persons with lower extremity amputations.

Science.gov (United States)

Bodenheimer, C; Kerrigan, A J; Garber, S L; Monga, T N

2000-06-15

There is a paucity of information regarding sexual functioning in persons with lower extremity amputations. The purpose of this study was to describe sexual and psychological functioning and health status in persons with lower extremity amputation. Self-report surveys assessed sexual functioning (Derogatis Inventory), depression (Beck Depression Inventory, anxiety (State-Trait Anxiety Inventory), and health status (Health Status Questionnaire) in a convenience sample of 30 men with lower extremity amputations. Mean age of the participants was 57 years (range 32-79). Mean duration since amputation was 23 months (range 3-634 months). Twenty one subjects (70%) had trans-tibial and seven subjects (23%) had trans-femoral amputations. A majority of subjects were experiencing problems in several domains of sexual functioning. Fifty three percent (n = 16) of the subjects were engaged in sexual intercourse or oral sex at least once a month. Twenty seven percent (n = 8) were masturbating at least once a month. Nineteen subjects (63%) reported orgasmic problems and 67% were experiencing erectile difficulties. Despite these problems, interest in sex was high in over 90% of the subjects. There was no evidence of increased prevalence of depression or anxiety in these subjects when compared to other outpatient adult populations. Sexual problems were common in the subjects studied. Despite these problems, interest in sex remained high. Few investigations have been directed toward identifying the psychological and social factors that may contribute to these problems and more research with a larger population is needed in this area.

Effective communication during difficult conversations.

Science.gov (United States)

Polito, Jacquelyn M

2013-06-01

A strong interest and need exist in the workplace today to master the skills of conducting difficult conversations. Theories and strategies abound, yet none seem to have found the magic formula with universal appeal and success. If it is such an uncomfortable skill to master is it better to avoid or initiate such conversations with employees? Best practices and evidence-based management guide us to the decision that quality improvement dictates effective communication, even when difficult. This brief paper will offer some suggestions for strategies to manage difficult conversations with employees. Mastering the skills of conducting difficult conversations is clearly important to keeping lines of communication open and productive. Successful communication skills may actually help to avert confrontation through employee engagement, commitment and appropriate corresponding behavior

Spatial planning via extremal optimization enhanced by cell-based local search

International Nuclear Information System (INIS)

Sidiropoulos, Epaminondas

2014-01-01

A new treatment is presented for land use planning problems by means of extremal optimization in conjunction to cell-based neighborhood local search. Extremal optimization, inspired by self-organized critical models of evolution has been applied mainly to the solution of classical combinatorial optimization problems. Cell-based local search has been employed by the author elsewhere in problems of spatial resource allocation in combination with genetic algorithms and simulated annealing. In this paper it complements extremal optimization in order to enhance its capacity for a spatial optimization problem. The hybrid method thus formed is compared to methods of the literature on a specific characteristic problem. It yields better results both in terms of objective function values and in terms of compactness. The latter is an important quantity for spatial planning. The present treatment yields significant compactness values as emergent results

Spatial extreme value analysis to project extremes of large-scale indicators for severe weather.

Science.gov (United States)

Gilleland, Eric; Brown, Barbara G; Ammann, Caspar M

2013-09-01

Concurrently high values of the maximum potential wind speed of updrafts ( W max ) and 0-6 km wind shear (Shear) have been found to represent conducive environments for severe weather, which subsequently provides a way to study severe weather in future climates. Here, we employ a model for the product of these variables (WmSh) from the National Center for Atmospheric Research/United States National Center for Environmental Prediction reanalysis over North America conditioned on their having extreme energy in the spatial field in order to project the predominant spatial patterns of WmSh. The approach is based on the Heffernan and Tawn conditional extreme value model. Results suggest that this technique estimates the spatial behavior of WmSh well, which allows for exploring possible changes in the patterns over time. While the model enables a method for inferring the uncertainty in the patterns, such analysis is difficult with the currently available inference approach. A variation of the method is also explored to investigate how this type of model might be used to qualitatively understand how the spatial patterns of WmSh correspond to extreme river flow events. A case study for river flows from three rivers in northwestern Tennessee is studied, and it is found that advection of WmSh from the Gulf of Mexico prevails while elsewhere, WmSh is generally very low during such extreme events. © 2013 The Authors. Environmetrics published by JohnWiley & Sons, Ltd.

To the fringe and back: Violent extremism and the psychology of deviance.

Science.gov (United States)

Kruglanski, Arie W; Jasko, Katarzyna; Chernikova, Marina; Dugas, Michelle; Webber, David

2017-04-01

We outline a general psychological theory of extremism and apply it to the special case of violent extremism (VE). Extremism is defined as motivated deviance from general behavioral norms and is assumed to stem from a shift from a balanced satisfaction of basic human needs afforded by moderation to a motivational imbalance wherein a given need dominates the others. Because motivational imbalance is difficult to sustain, only few individuals do, rendering extreme behavior relatively rare, hence deviant. Thus, individual dynamics translate into social patterns wherein majorities of individuals practice moderation, whereas extremism is the province of the few. Both extremism and moderation require the ability to successfully carry out the activities that these demand. Ability is partially determined by the activities' difficulty, controllable in part by external agents who promote or oppose extremism. Application of this general framework to VE identifies the specific need that animates it and offers broad guidelines for addressing this pernicious phenomenon. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Hygienic diagnosis in extreme conditions

International Nuclear Information System (INIS)

Sofronov, G.A.

1997-01-01

Review for book by M.P. Zakharchenko, S.A. Lopatin, G.N. Novozhilov, V.I. Zakharov Hygienic diagnosis in extreme conditions is presented discussing the problem of people health preservation under extreme conditions. Hygienic diagnosis is considered illustrated by cases of hostilities (Afghan War), earthquake response in Armenia (1988) and Chernobyl accident response. Attention is paid to the estimation of radiation doses to people and characteristics of main types of dosimeters. The high scientific level of the book is marked

Digital dice computational solutions to practical probability problems

CERN Document Server

Nahin, Paul J

2013-01-01

Some probability problems are so difficult that they stump the smartest mathematicians. But even the hardest of these problems can often be solved with a computer and a Monte Carlo simulation, in which a random-number generator simulates a physical process, such as a million rolls of a pair of dice. This is what Digital Dice is all about: how to get numerical answers to difficult probability problems without having to solve complicated mathematical equations. Popular-math writer Paul Nahin challenges readers to solve twenty-one difficult but fun problems, from determining the

PREDICTION OF THE EXTREMAL SHAPE FACTOR OF SPHEROIDAL PARTICLES

Directory of Open Access Journals (Sweden)

Daniel Hlubinka

2011-05-01

Full Text Available In the stereological unfolding problem for spheroidal particles the extremal shape factor is predicted. The theory of extreme values has been used to show that extremes of the planar shape factor of particle sections tend to the same limit distribution as extremes of the original shape factor for both the conditional and marginal distribution. Attention is then paid to the extreme shape factor conditioned by the particle size. Normalizing constants are evaluated for a parametric model and the numerical procedure is tested on real data from metallography.

Maritime Military Decision Making in Environments of Extreme Information Ambiguity: An Initial Exploration

National Research Council Canada - National Science Library

Reeves, Andrew T

2005-01-01

... to make effective decisions. An environment of extreme information ambiguity, a dependent variable, is one of the most difficult components of a battle where the decision maker may reach a confusing and debilitating point...

Extremity doses to interventional radiologists

International Nuclear Information System (INIS)

Wihtby, M.; Martin, C. J.

2002-01-01

Radiologists performing interventional procedures are often required to stand close to the patient's side when carrying out manipulations under fluoroscopic control. This can result in their extremities receiving a high radiation dose, due to scattered radiation. These doses are sometimes high enough to warrant that the radiologist in question be designated a classified radiation worker. Classification in the UK is a result of any worker receiving or likely to receive in the course of their duties in excess of 3/10ths of any annual dose limit (500mSv to extremities, skin). The doses to the legs of radiologists have received less attention than those to the hands, however the doses may be high, due to the proximity of the legs and feet to scattered radiation. The legs can be exposed to a relatively high level of scattered radiation as the radiation in produced from scatter of the un attenuated beam from the bottom of the patient couch. The routine monitoring of extremity doses in interventional radiology is difficult due to several factors. Firstly a wide range of interventional procedures in undertaken in every radiology department, and these procedures require many different techniques, equipment and skills. This means that the position the radiologist adopts in relation to scattering medium and therefore their exposure, depends heavily on the type of procedure. As the hands which manipulate the catheters within the patient are often located close to the patients side and to the area under irradiation, the distribution of dose across the hands can be variable, with very high localised doses, making routine monitoring difficult. The purpose of this study was to determine the magnitude and distribution of dose to the hands and legs of interventional radiologists carrying out a wide range of both diagnostic and therapeutic interventional procedures. To ascertain the most effective method of monitoring the highest dose in accordance with the Basic safety standards

Why do people buy dogs with potential welfare problems related to extreme conformation and inherited disease? A representative study of Danish owners of four small dog breeds.

Science.gov (United States)

Sandøe, P; Kondrup, S V; Bennett, P C; Forkman, B; Meyer, I; Proschowsky, H F; Serpell, J A; Lund, T B

2017-01-01

A number of dog breeds suffer from welfare problems due to extreme phenotypes and high levels of inherited diseases but the popularity of such breeds is not declining. Using a survey of owners of two popular breeds with extreme physical features (French Bulldog and Chihuahua), one with a high load of inherited diseases not directly related to conformation (Cavalier King Charles Spaniel), and one representing the same size range but without extreme conformation and with the same level of disease as the overall dog population (Cairn Terrier), we investigated this seeming paradox. We examined planning and motivational factors behind acquisition of the dogs, and whether levels of experienced health and behavior problems were associated with the quality of the owner-dog relationship and the intention to re-procure a dog of the same breed. Owners of each of the four breeds (750/breed) were randomly drawn from a nationwide Danish dog registry and invited to participate. Of these, 911 responded, giving a final sample of 846. There were clear differences between owners of the four breeds with respect to degree of planning prior to purchase, with owners of Chihuahuas exhibiting less. Motivations behind choice of dog were also different. Health and other breed attributes were more important to owners of Cairn Terriers, whereas the dog's personality was reported to be more important for owners of French Bulldogs and Cavalier King Charles Spaniels but less important for Chihuahua owners. Higher levels of health and behavior problems were positively associated with a closer owner-dog relationship for owners of Cavalier King Charles Spaniels and Chihuahuas but, for owners of French Bulldogs, high levels of problems were negatively associated with an intention to procure the same breed again. In light of these findings, it appears less paradoxical that people continue to buy dogs with welfare problems.

Techniques for applying subatmospheric pressure dressing to wounds in difficult regions of anatomy.

Science.gov (United States)

Greer, S E; Duthie, E; Cartolano, B; Koehler, K M; Maydick-Youngberg, D; Longaker, M T

1999-09-01

Subatmospheric pressure dressing (SPD) has been commercially available in the United States since 1995 as the vacuum-assisted closure (VAC) device. SPD increases local blood flow, decreases edema and bacterial count, and promotes the formation of granulation tissue. Despite recent clinical successes with the use of SPD in a variety of wound types, problems may occur with application of VAC system in certain areas of the body. The main limitation occurs when attempting to maintain an airtight seal over irregular surfaces surrounding a wound. For example, application of the adhesive drape and creation of a seal are particularly difficulty in the hip and perineum. In addition, wounds of the lower extremity can occur in multiple sites, posing the problem of providing a vacuum dressing to more than one wound from one suction pump machine. To address these challenging clinical wounds, we have developed techniques to allow the successful application of SPD to sacral pressure ulcers near the anus, and to multiple large lower extremity ulcers.

Transductive and matched-pair machine learning for difficult target detection problems

Science.gov (United States)

Theiler, James

2014-06-01

This paper will describe the application of two non-traditional kinds of machine learning (transductive machine learning and the more recently proposed matched-pair machine learning) to the target detection problem. The approach combines explicit domain knowledge to model the target signal with a more agnostic machine-learning approach to characterize the background. The concept is illustrated with simulated data from an elliptically-contoured background distribution, on which a subpixel target of known spectral signature but unknown spatial extent has been implanted.

Arctic sea ice, Eurasia snow, and extreme winter haze in China.

Science.gov (United States)

Zou, Yufei; Wang, Yuhang; Zhang, Yuzhong; Koo, Ja-Ho

2017-03-01

The East China Plains (ECP) region experienced the worst haze pollution on record for January in 2013. We show that the unprecedented haze event is due to the extremely poor ventilation conditions, which had not been seen in the preceding three decades. Statistical analysis suggests that the extremely poor ventilation conditions are linked to Arctic sea ice loss in the preceding autumn and extensive boreal snowfall in the earlier winter. We identify the regional circulation mode that leads to extremely poor ventilation over the ECP region. Climate model simulations indicate that boreal cryospheric forcing enhances the regional circulation mode of poor ventilation in the ECP region and provides conducive conditions for extreme haze such as that of 2013. Consequently, extreme haze events in winter will likely occur at a higher frequency in China as a result of the changing boreal cryosphere, posing difficult challenges for winter haze mitigation but providing a strong incentive for greenhouse gas emission reduction.

Study of neutronic problems related to the xenon instability in the pressurized water reactor

International Nuclear Information System (INIS)

Mathonniere, G.

1988-03-01

Xenon instabilities lead to increase initial errors. So it is extremely difficult to get an accurate calculation schema able to deal with these problems which are very important for electrical grid whose electronuclear output is large. The main task was to build a tridimensional calculation schema including nuclear, thermal hydraulic feedback. It was qualified by comparing its results with an actual experiment. Many technical problems were investigated through analytical studies or calculation results: time step, spatial mesh, finite element, convergence criterion, modelization for grids and fast control rod moves. Moreover, a 1D model, for less expensive, was studied. Its comparison with the 3D results allowed to check its accuracy and to validate the modelization of the radial laplacien and the modelization of the control rods [fr

DIRECTIONS OF EXTREME TOURISM IN UKRAINE

Directory of Open Access Journals (Sweden)

L. V. Martseniuk

2016-02-01

Full Text Available Purpose. In the world market of tourist services the extreme tourism is very popular, as it does not require the significant financial costs and enables year on year to increase the offers of holiday packages, associated with active travel. Ukraine has significant potential for the development of extreme kinds of rest, but it is not developed enough. Forms of extreme tourism are unknown for domestic tourists, and therefore, they formed a negative attitude. The aim of the article is the analysis of extreme resort potential of Ukraine and promotion of the development of extreme tourism destinations in the travel market. Theoretical and methodological basis of research is the system analysis of the problems of ensuring the competitiveness of the tourism industry, theoretical principles of economic science in the field of the effectiveness of extreme tourism and management of tourist flows. Methodology. The author offers the directions of tourist flows control, which differ from the current expansion of services to tourists in Ukraine. The development of extreme tourism with the help of co-operation of railways and sport federations was proposed. Findings. During the research the author proved that the implementation of the tasks will be promote: 1 increase in budget revenues at all levels of the inner extreme tourism; 2 raise the image of Ukraine and Ukrainian Railways; 3 increase the share of tourism and resorts in the gross domestic product to the level of developed countries; 4 bringing the number of employees in tourism and resorts to the level of developed countries; 5 the creation of an effective system of monitoring the quality of tourist services; 6 the creation of an attractive investment climate for attracting the investment in the broad development of tourism, engineering and transport and municipal infrastructure; 7 improvement the safety of tourists, ensure the effective protection of their rights and legitimate interests and

Pediatric lower extremity mower injuries.

Science.gov (United States)

Hill, Sean M; Elwood, Eric T

2011-09-01

Lawn mower injuries in children represent an unfortunate common problem to the plastic reconstructive surgeon. There are approximately 68,000 per year reported in the United States. Compounding this problem is the fact that a standard treatment algorithm does not exist. This study follows a series of 7 pediatric patients treated for lower extremity mower injuries by a single plastic surgeon. The extent of soft tissue injury varied. All patients were treated with negative pressure wound therapy as a bridge to definitive closure. Of the 7 patients, 4 required skin grafts, 1 required primary closure, 1 underwent a lower extremity amputation secondary to wounds, and 1 was repaired using a cross-leg flap. Function limitations were minimal for all of our patients after reconstruction. Our basic treatment algorithm is presented with initial debridement followed by the simplest method possible for wound closure using negative pressure wound therapy, if necessary.

Extreme Value Theory Approach to Simultaneous Monitoring and Thresholding of Multiple Risk Indicators

NARCIS (Netherlands)

Einmahl, J.H.J.; Li, J.; Liu, R.Y.

2006-01-01

Risk assessments often encounter extreme settings with very few or no occurrences in reality.Inferences about risk indicators in such settings face the problem of insufficient data.Extreme value theory is particularly well suited for handling this type of problems.This paper uses a multivariate

Challenging problems in algebra

CERN Document Server

Posamentier, Alfred S

1996-01-01

Over 300 unusual problems, ranging from easy to difficult, involving equations and inequalities, Diophantine equations, number theory, quadratic equations, logarithms, more. Detailed solutions, as well as brief answers, for all problems are provided.

The 50-th anniversary of the Federal Department for Biomedical and Extreme Problems at the Ministry of Health of Russia

International Nuclear Information System (INIS)

Reva, V.D.

1997-01-01

Due to the 50-th anniversary of the Federal Department for Biomedical and Extreme Problems of the Ministry of Health of Russian Federation, formerly the Third Main Department of the USSR Ministry of Health the, basic stages are considered of the establishment and development of this system amalgamating treatment-and-prophylactic, sanitary-and-antiepidemic, scientific and industrial institutions aimed at the health protection of personnel dealing with ionizing radiation. Organizational and staff structures are discussed as well as activities of the institutions of the Department under present economic conditions

Risk analysis and solving the nuclear waste siting problem

International Nuclear Information System (INIS)

Inhaber, H.

1994-01-01

In spite of millions of dollars and countless human resources being expended on finding nuclear wastes sites, the search has proved extremely difficult for the nuclear industry. This may be due to the approach followed, rather than inadequacies in research or funding. A new approach to the problem, the reverse Dutch auction, is suggested. It retains some of the useful elements of the present system, but it also adds new ones. It allows natural market forces to set the level of compensation, rather than relying on close-door negotiations or theoretical calculations. Two flow charts show the pre-bid and post-bid steps of the reverse Duch auction system of Inhaber. It is assumed that a state wishes to site a waste facility somewhere in its boundaries. 22 refs., 3 figs

Numerical solution of the state-delayed optimal control problems by a fast and accurate finite difference θ-method

Science.gov (United States)

Hajipour, Mojtaba; Jajarmi, Amin

2018-02-01

Using the Pontryagin's maximum principle for a time-delayed optimal control problem results in a system of coupled two-point boundary-value problems (BVPs) involving both time-advance and time-delay arguments. The analytical solution of this advance-delay two-point BVP is extremely difficult, if not impossible. This paper provides a discrete general form of the numerical solution for the derived advance-delay system by applying a finite difference θ-method. This method is also implemented for the infinite-time horizon time-delayed optimal control problems by using a piecewise version of the θ-method. A matrix formulation and the error analysis of the suggested technique are provided. The new scheme is accurate, fast and very effective for the optimal control of linear and nonlinear time-delay systems. Various types of finite- and infinite-time horizon problems are included to demonstrate the accuracy, validity and applicability of the new technique.

Extreme climatic events in relation to global change and their impact on life histories

Directory of Open Access Journals (Sweden)

Juan MORENO, Anders Pape Møller

2011-06-01

Full Text Available Extreme weather conditions occur at an increasing rate as evidenced by higher frequency of hurricanes and more extreme precipitation and temperature anomalies. Such extreme environmental conditions will have important implications for all living organisms through greater frequency of reproductive failure and reduced adult survival. We review examples of reproductive failure and reduced survival related to extreme weather conditions. Phenotypic plasticity may not be sufficient to allow adaptation to extreme weather for many animals. Theory predicts reduced reproductive effort as a response to increased stochasticity. We predict that patterns of natural selection will change towards truncation selection as environmental conditions become more extreme. Such changes in patterns of selection may facilitate adaptation to extreme events. However, effects of selection on reproductive effort are difficult to detect. We present a number of predictions for the effects of extreme weather conditions in need of empirical tests. Finally, we suggest a number of empirical reviews that could improve our ability to judge the effects of extreme environmental conditions on life history [Current Zoology 57 (3: 375–389, 2011].

Infill sampling criteria to locate extremes

CSIR Research Space (South Africa)

Watson, AG

1995-07-01

Full Text Available Three problem-dependent meanings for engineering ''extremes'' are motivated, established, and translated into formal geostatistical (model-based) criteria for designing infill sample networks. (I) Locate an area within the domain of interest where a...

Design, fabrication, and characterization of high-efficiency extreme ultraviolet diffusers

Energy Technology Data Exchange (ETDEWEB)

Naulleau, Patrick P.; Liddle, J. Alexander; Salmassi, Farhad; Anderson, Erik H.; Gullikson, Eric M.

2004-02-19

As the development of extreme ultraviolet (EUV) lithography progresses, interest grows in the extension of traditional optical components to the EUV regime. The strong absorption of EUV by most materials and its extremely short wavelength, however, makes it very difficult to implement many components that are commonplace in the longer wavelength regimes. One such example is the diffuser often implemented with ordinary ground glass in the visible light regime. Here we demonstrate the fabrication of reflective EUV diffusers with high efficiency within a controllable bandwidth. Using these techniques we have fabricated diffusers with efficiencies exceeding 10% within a moderate angular single-sided bandwidth of approximately 0.06 radians.

Consistency of extreme flood estimation approaches

Science.gov (United States)

Felder, Guido; Paquet, Emmanuel; Penot, David; Zischg, Andreas; Weingartner, Rolf

2017-04-01

Estimations of low-probability flood events are frequently used for the planning of infrastructure as well as for determining the dimensions of flood protection measures. There are several well-established methodical procedures to estimate low-probability floods. However, a global assessment of the consistency of these methods is difficult to achieve, the "true value" of an extreme flood being not observable. Anyway, a detailed comparison performed on a given case study brings useful information about the statistical and hydrological processes involved in different methods. In this study, the following three different approaches for estimating low-probability floods are compared: a purely statistical approach (ordinary extreme value statistics), a statistical approach based on stochastic rainfall-runoff simulation (SCHADEX method), and a deterministic approach (physically based PMF estimation). These methods are tested for two different Swiss catchments. The results and some intermediate variables are used for assessing potential strengths and weaknesses of each method, as well as for evaluating the consistency of these methods.

Overcoming difficult conversations in clinical supervision

Directory of Open Access Journals (Sweden)

Williams B

2016-06-01

Full Text Available Brett Williams,1 Christine King,1 Tanya Edlington,21Department of Community Emergency Health and Paramedic Practice, Monash University, Franskton, VIC, 2The Conversation Clinic Pty Ltd, Melbourne, VIC, Australia Background: Clinical supervisors are responsible for managing many facets of clinical learning and face a range of challenges when the need for "difficult" conversations arises, including the need to manage conflict and relationships. Methods: Spotlight on Conversations Workshop was developed to improve the capacity of clinical supervisors to engage in difficult conversations. They were designed to challenge the mindset of clinical supervisors about difficult conversations with students, the consequences of avoiding difficult conversations, and to offer activities for practicing difficult conversations. Preworkshop, postworkshop, and 4-month follow-up evaluations assessed improvements in knowledge, intent to improve, and confidence along with workshop satisfaction. Results: Nine workshops were delivered in a range of locations across Victoria, Australia, involving a total of 117 clinical supervisors. Preworkshop evaluations illustrated that more than half of the participants had avoided up to two difficult conversations in the last month in their workplace. Postworkshop evaluation at 4 months showed very high levels of satisfaction with the workshop's relevancy, content, and training, as well as participants' intention to apply knowledge and skills. Also shown were significant changes in participants' confidence to have difficult conversations not only with students but also with other peers and colleagues. In follow-up in-depth interviews with 20 of the 117 participants, 75% said they had made definite changes in their practice because of what they learned in the workshop and another 10% said they would make changes to their practice, but had not had the opportunity yet to do so. Conclusion: We conclude that the Spotlight on

Risk Factors for Lower-Extremity Injuries Among Contemporary Dance Students.

Science.gov (United States)

van Seters, Christine; van Rijn, Rogier M; van Middelkoop, Marienke; Stubbe, Janine H

2017-10-10

To determine whether student characteristics, lower-extremity kinematics, and strength are risk factors for sustaining lower-extremity injuries in preprofessional contemporary dancers. Prospective cohort study. Codarts University of the Arts. Forty-five first-year students of Bachelor Dance and Bachelor Dance Teacher. At the beginning of the academic year, the injury history (only lower-extremity) and student characteristics (age, sex, educational program) were assessed using a questionnaire. Besides, lower-extremity kinematics [single-leg squat (SLS)], strength (countermovement jump) and height and weight (body mass index) were measured during a physical performance test. Substantial lower-extremity injuries during the academic year were defined as any problems leading to moderate or severe reductions in training volume or in performance, or complete inability to participate in dance at least once during follow-up as measured with the Oslo Sports Trauma Research Center (OSTRC) Questionnaire on Health Problems. Injuries were recorded on a monthly basis using a questionnaire. Analyses on leg-level were performed using generalized estimating equations to test the associations between substantial lower-extremity injuries and potential risk factors. The 1-year incidence of lower-extremity injuries was 82.2%. Of these, 51.4% was a substantial lower-extremity injury. Multivariate analyses identified that ankle dorsiflexion during the SLS (OR 1.25; 95% confidence interval, 1.03-1.52) was a risk factor for a substantial lower-extremity injury. The findings indicate that contemporary dance students are at high risk for lower-extremity injuries. Therefore, the identified risk factor (ankle dorsiflexion) should be considered for prevention purposes.

Angiography of the upper extremity

International Nuclear Information System (INIS)

Janevski, B.K.

1982-01-01

This thesis provides a description of the technical and medical aspects of arteriography of the upper extremity and an extensive analysis of the angiographic anatomy and pathology of 750 selective studies performed in more than 500 patients. A short historical review is provided of angiography as a whole and of arteriography of the hand in particular. The method of percutaneous transfemoral catheterization of the arteries of the upper extremity and particularly the arteries of the hand is considered, discussing the problems the angiographer encounters frequently, describing the angiographic complications which may occur and emphasizing the measures to keep them to a minimum. The use of vasodilators in hand angiography is discussed. A short description of the embryological patterns persisting in the arteries of the arm is included in order to understand the congenital variations of the arteries of the upper extremity. The angiographic patterns and clinical aspects of the most common pathological processes involving the arteries of the upper extremities are presented. Special attention is paid to the correlation between angiography and pathology. (Auth.)

The stories they tell: How third year medical students portray patients, family members, physicians, and themselves in difficult encounters.

Science.gov (United States)

Shapiro, Johanna; Rakhra, Pavandeep; Wong, Adrianne

2016-10-01

Physicians have long had patients whom they have labeled "difficult", but little is known about how medical students perceive difficult encounters with patients. In this study, we analyzed 134 third year medical students' reflective essays written over an 18-month period about difficult student-patient encounters. We used a qualitative computerized software program, Atlas.ti to analyze students' observations and reflections. Main findings include that students described patients who were angry and upset; noncompliant with treatment plans; discussed "nonmedical" problems; fearful, worried, withdrawn, or "disinterested" in their health. Students often described themselves as anxious, uncertain, confused, and frustrated. Nevertheless, they saw themselves behaving in empathic and patient-centered ways while also taking refuge in "standard" behaviors not necessarily appropriate to the circumstances. Students rarely mentioned receiving guidance from attendings regarding how to manage these challenging interactions. These third-year medical students recognized the importance of behaving empathically in difficult situations and often did so. However, they often felt overwhelmed and frustrated, resorting to more reductive behaviors that did not match the needs of the patient. Students need more guidance from attending physicians in order to approach difficult interactions with specific problem-solving skills while maintaining an empathic, patient-centered context.

Determining extreme parameter correlation in ground water models

DEFF Research Database (Denmark)

Hill, Mary Cole; Østerby, Ole

2003-01-01

can go undetected even by experienced modelers. Extreme parameter correlation can be detected using parameter correlation coefficients, but their utility depends on the presence of sufficient, but not excessive, numerical imprecision of the sensitivities, such as round-off error. This work...... investigates the information that can be obtained from parameter correlation coefficients in the presence of different levels of numerical imprecision, and compares it to the information provided by an alternative method called the singular value decomposition (SVD). Results suggest that (1) calculated...... correlation coefficients with absolute values that round to 1.00 were good indicators of extreme parameter correlation, but smaller values were not necessarily good indicators of lack of correlation and resulting unique parameter estimates; (2) the SVD may be more difficult to interpret than parameter...

LDRD final report for improving human effectiveness for extreme-scale problem solving : assessing the effectiveness of electronic brainstorming in an industrial setting.

Energy Technology Data Exchange (ETDEWEB)

Dornburg, Courtney C.; Stevens, Susan Marie; Davidson, George S.; Hendrickson, Stacey M. Langfitt

2008-09-01

An experiment was conducted comparing the effectiveness of individual versus group electronic brainstorming in order to address difficult, real world challenges. While industrial reliance on electronic communications has become ubiquitous, empirical and theoretical understanding of the bounds of its effectiveness have been limited. Previous research using short-term, laboratory experiments have engaged small groups of students in answering questions irrelevant to an industrial setting. The present experiment extends current findings beyond the laboratory to larger groups of real-world employees addressing organization-relevant challenges over the course of four days. Employees and contractors at a national security laboratory participated, either in a group setting or individually, in an electronic brainstorm to pose solutions to a 'wickedly' difficult problem. The data demonstrate that (for this design) individuals perform at least as well as groups in producing quantity of electronic ideas, regardless of brainstorming duration. However, when judged with respect to quality along three dimensions (originality, feasibility, and effectiveness), the individuals significantly (p<0.05) out-performed the group working together. When idea quality is used as the benchmark of success, these data indicate that work-relevant challenges are better solved by aggregating electronic individual responses, rather than electronically convening a group. This research suggests that industrial reliance upon electronic problem solving groups should be tempered, and large nominal groups might be the more appropriate vehicle for solving wicked corporate issues.

Modeling visual problem solving as analogical reasoning.

Science.gov (United States)

Lovett, Andrew; Forbus, Kenneth

2017-01-01

We present a computational model of visual problem solving, designed to solve problems from the Raven's Progressive Matrices intelligence test. The model builds on the claim that analogical reasoning lies at the heart of visual problem solving, and intelligence more broadly. Images are compared via structure mapping, aligning the common relational structure in 2 images to identify commonalities and differences. These commonalities or differences can themselves be reified and used as the input for future comparisons. When images fail to align, the model dynamically rerepresents them to facilitate the comparison. In our analysis, we find that the model matches adult human performance on the Standard Progressive Matrices test, and that problems which are difficult for the model are also difficult for people. Furthermore, we show that model operations involving abstraction and rerepresentation are particularly difficult for people, suggesting that these operations may be critical for performing visual problem solving, and reasoning more generally, at the highest level. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Chiral gravity, log gravity, and extremal CFT

International Nuclear Information System (INIS)

Maloney, Alexander; Song Wei; Strominger, Andrew

2010-01-01

We show that the linearization of all exact solutions of classical chiral gravity around the AdS 3 vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

Malignant bone tumors of the pelvis and of the extremities

International Nuclear Information System (INIS)

Gullotta, U.; Reiser, M.; Feuerbach, S.; Biehl, T.; Technische Univ. Muenchen

1981-01-01

Bone tumors of the extremities are usually diagnosed by conventional radiography. A good angiogram may render information not only about intra- and extraosseous extension of the tumor, but often also about the biological dignity. CT is usually not necessary, especially since it is sometimes difficult to define the extraosseous borders of these extremity tumors with this method. In bone tumors of the pelvis, however, neither conventional radiography nor angiography render reliable information about the extent of the tumor, which CT is very well able to do. Therefore CT is primarily indicated for evaluation of bone tumors in this region. Angiography is done only for preoperative evaluation of the vascular architecture or for potential therapeutic embolisation. (orig.) [de

Organizing of medical ensurance of human population under extreme conditions. Summaries of reports of scientific-practical conference

International Nuclear Information System (INIS)

1994-01-01

Summary of reports are presented of Scientific-Practical conference on the organizing of medical ensurance of human population under extreme conditions including radiation accidents. The conference held in Moscow in October, 1994. It covered problems of organizing medical ensurance of population, medical surveillance problems, sanitary-hygienic and epidemiological problems (including radiation protection), and medical provision problems under extreme conditions

Dynamical properties and extremes of Northern Hemisphere climate fields over the past 60 years

Science.gov (United States)

Faranda, Davide; Messori, Gabriele; Alvarez-Castro, M. Carmen; Yiou, Pascal

2017-12-01

Atmospheric dynamics are described by a set of partial differential equations yielding an infinite-dimensional phase space. However, the actual trajectories followed by the system appear to be constrained to a finite-dimensional phase space, i.e. a strange attractor. The dynamical properties of this attractor are difficult to determine due to the complex nature of atmospheric motions. A first step to simplify the problem is to focus on observables which affect - or are linked to phenomena which affect - human welfare and activities, such as sea-level pressure, 2 m temperature, and precipitation frequency. We make use of recent advances in dynamical systems theory to estimate two instantaneous dynamical properties of the above fields for the Northern Hemisphere: local dimension and persistence. We then use these metrics to characterize the seasonality of the different fields and their interplay. We further analyse the large-scale anomaly patterns corresponding to phase-space extremes - namely time steps at which the fields display extremes in their instantaneous dynamical properties. The analysis is based on the NCEP/NCAR reanalysis data, over the period 1948-2013. The results show that (i) despite the high dimensionality of atmospheric dynamics, the Northern Hemisphere sea-level pressure and temperature fields can on average be described by roughly 20 degrees of freedom; (ii) the precipitation field has a higher dimensionality; and (iii) the seasonal forcing modulates the variability of the dynamical indicators and affects the occurrence of phase-space extremes. We further identify a number of robust correlations between the dynamical properties of the different variables.

Automatic residue removal for high-NA extreme illumination

Science.gov (United States)

Moon, James; Nam, Byong-Sub; Jeong, Joo-Hong; Kong, Dong-Ho; Nam, Byung-Ho; Yim, Dong Gyu

2007-10-01

An epidemic for smaller node has been that, as the device architecture shrinks, lithography process requires high Numerical Aperture (NA), and extreme illumination system. This, in turn, creates many lithography problems such as low lithography process margin (Depth of Focus, Exposure Latitude), unstable Critical Dimension (CD) uniformity and restricted guideline for device design rule and so on. Especially for high NA, extreme illumination such as immersion illumination systems, above all the related problems, restricted design rule due to forbidden pitch is critical and crucial issue. This forbidden pitch is composed of numerous optical effects but majority of these forbidden pitch compose of photo resist residue and these residue must be removed to relieve some room for already tight design rule. In this study, we propose automated algorithm to remove photo resist residue due to high NA and extreme illumination condition. This algorithm automatically self assembles assist patterns based on the original design layout, therefore insuring the safety and simplicity of the generated assist pattern to the original design and removes any resist residue created by extreme illumination condition. Also we tested our automated algorithm on full chip FLASH memory device and showed the residue removal effect by using commercial verification tools as well as on actual test wafer.

SPECIFICITY OF SELF-PRESERVATION MOTIVATION IN EXTREME SITUATION

Directory of Open Access Journals (Sweden)

Ekaterina Anatolevna Karacheva

2015-02-01

Full Text Available The article presents the results of the study motivation of self-preservation in an extreme situation. Usually extreme situation unfold from the point of view of functioning, health, high negative level mental stress and tension. The extreme situation is the situation of human activity to which man acts, carrying out certain activities. The article provides an overview of russian and foreign authors dealing with this problem. Theoretical models of motivation of self-preservation Z. Freud, A. Maslow, G. Murray, M. Magomed-Eminov. The study explores the leading motivation in an extreme situation and analyzed the levels of motivation of self-preservation. The study was conducted in the Afghan veterans, using a method of unfinished sentences and other. Identified two levels of motivation of self-preservation: individual and personal. Revealed that the motivation of self-preservation is the leading motivation in an extreme situation.

Arm Volumetry Versus Upper Extremity Lymphedema Index: Validity of Upper Extremity Lymphedema Index for Body-Type Corrected Arm Volume Evaluation.

Science.gov (United States)

Yamamoto, Nana; Yamamoto, Takumi; Hayashi, Nobuko; Hayashi, Akitatsu; Iida, Takuya; Koshima, Isao

2016-06-01

Volumetry, measurement of extremity volume, is a commonly used method for upper extremity lymphedema (UEL) evaluation. However, comparison between different patients with different physiques is difficult with volumetry, because body-type difference greatly affects arm volume. Seventy arms of 35 participants who had no history of arm edema or breast cancer were evaluated. Arm volume was calculated using a summed truncated cone model, and UEL index was calculated using circumferences and body mass index (BMI). Examinees' BMI was classified into 3 groups, namely, low BMI (BMI, 25 kg/m). Arm volume and UEL index were compared with corresponding BMI groups. Mean (SD) arm volume was 1090.9 (205.5) mL, and UEL index 96.9 (5.6). There were significant differences in arm volume between BMI groups [low BMI vs middle BMI vs high BMI, 945.2 (107.4) vs 1045.2 (87.5) vs 1443.1 (244.4) mL, P 0.5]. Arm volume significantly increased with increase of BMI, whereas UEL index stayed constant regardless of BMI. Upper extremity lymphedema index would allow better body-type corrected arm volume evaluation compared with arm volumetry.

Detecting change-points in extremes

KAUST Repository

Dupuis, D. J.

2015-01-01

Even though most work on change-point estimation focuses on changes in the mean, changes in the variance or in the tail distribution can lead to more extreme events. In this paper, we develop a new method of detecting and estimating the change-points in the tail of multiple time series data. In addition, we adapt existing tail change-point detection methods to our specific problem and conduct a thorough comparison of different methods in terms of performance on the estimation of change-points and computational time. We also examine three locations on the U.S. northeast coast and demonstrate that the methods are useful for identifying changes in seasonally extreme warm temperatures.

Advanced Life Systems for Extreme Environments: An Arctic Application

Science.gov (United States)

Lewis, Carol E.; Stanford, Kerry L.; Bubenheim, David L.; Covington, Alan (Technical Monitor)

1995-01-01

The problems of obtaining adequate pure drinking water and disposing of liquid and solid waste in the U.S. Arctic, a region where virtually all water is frozen solid for much of the year, has led to unsanitary solutions (U.S. Arctic Research Commission). These solutions are also damaging to the environment. Sanitation and a safe water supply are particularly problems in rural villages. About one-fourth of Alaska's 86.000 Native residents live in these communities. They are without running water and use plastic buckets for toilets. The outbreak of diseases is believed to be partially attributable to exposure to human waste. Villages with the most frequent outbreaks of disease are those in which running water is difficult to obtain (Office of Technology Assessment, 1994). Waste is emptied into open lagoons, rivers, or onto the sea coast. It does not degrade rapidly and in addition to affecting human health, can be harmful to the fragile ecology of the Arctic and the indigenous wildlife and fish populations. Advanced Life Systems for Extreme Environments (ALSEE) provides a solution to sanitation and safe water problems. The system uses an advanced integrated technology developed for Antarctic and space applications. ALSEE uses the systems approach to address more than waste and water problems. By incorporating hydroponic horticulture and aquaculture into the waste treatment system, ALSEE addresses the quality and quantity of fresh foods available to Arctic residents. A temperate climate is required for year-round plant growth. ALSEE facilities can be designed to include a climate controlled area within the structure. This type of environment is a change from the long periods of darkness and cold found in the Arctic and can help alleviate stress so often associated with these extremes. While the overall concept of ALSEE projects is advanced, system facilities can be operated by village residents with appropriate training. ALSEE provides continuing training and

An overview on extremity dosimetry in medical applications

International Nuclear Information System (INIS)

Vanhavere, F.; Carinou, E.; Donadille, L.; Ginjaume, M.; Jankowski, J.; Rimpler, A.; Sans Merce, M.

2008-01-01

Some activities of EURADOS Working Group 9 (WG9) are presently funded by the European Commission (CONRAD project). The objective of WG9 is to promote and co-ordinate research activities for the assessment of occupational exposures to staff at workplaces in interventional radiology (IR) and nuclear medicine. For some of these applications, the skin of the fingers is the limiting organ for individual monitoring of external radiation. Therefore, sub-group 1 of WG9 deals with the use of extremity dosemeters in medical radiation fields. The wide variety of radiation field characteristics present in a medical environment together with the difficulties in measuring a local dose that is representative for the maximum skin dose, usually with one single detector, makes it difficult to perform accurate extremity dosimetry. Sub-group 1 worked out a thorough literature review on extremity dosimetry issues in diagnostic and therapeutic nuclear medicine and positron emission tomography, interventional radiology and interventional cardiology and brachytherapy. Some studies showed that the annual dose limits could be exceeded if the required protection measures are not taken, especially in nuclear medicine. The continuous progress in new applications and techniques requires an important effort in radiation protection and training. (authors)

Management of the difficult airway.

Science.gov (United States)

Schwartz, D E; Wiener-Kronish, J P

1991-09-01

For clinicians involved in airway management, a plan of action for dealing with the difficult airway or a failed intubation should be developed well in advance of encountering a patient in whom intubation is not routine. When difficulty is anticipated, the equipment necessary for performing a difficult intubation should be immediately available. It also is prudent to have a surgeon skilled in performing a tracheotomy and a criothyroidotomy stand by. The intubation should be attempted in the awake state, preferably using the fiberoptic bronchoscope. The more challenging situation is when the difficult airway is confronted unexpectedly. After the first failed attempt at laryngoscopy, head position should be checked and the patient ventilated with oxygen by mask. A smaller styletted tube and possibly a different laryngoscope blade should be selected for a second attempt at intubation. The fiberoptic bronchoscope and other equipment for difficult intubation should be obtained. A second attempt should then be made. If this is unsuccessful, the patient should be reoxygenated, and assistance including a skilled anesthesiologist and surgeon should be summoned. On a third attempt, traction to the tongue can be applied by an assistant, a tube changer could be used to enter the larynx, or one of the other special techniques previously described can be used. If this third attempt fails, it may be helpful to have a physician more experienced in airway management attempt intubation after oxygen has been administered to the patient. If all attempts are unsuccessful, then invasive techniques to secure the airway will have to be performed.

Interevent Time Distribution of Renewal Point Process, Case Study: Extreme Rainfall in South Sulawesi

Science.gov (United States)

Sunusi, Nurtiti

2018-03-01

The study of time distribution of occurrences of extreme rain phenomena plays a very important role in the analysis and weather forecast in an area. The timing of extreme rainfall is difficult to predict because its occurrence is random. This paper aims to determine the inter event time distribution of extreme rain events and minimum waiting time until the occurrence of next extreme event through a point process approach. The phenomenon of extreme rain events over a given period of time is following a renewal process in which the time for events is a random variable τ. The distribution of random variable τ is assumed to be a Pareto, Log Normal, and Gamma. To estimate model parameters, a moment method is used. Consider Rt as the time of the last extreme rain event at one location is the time difference since the last extreme rainfall event. if there are no extreme rain events up to t 0, there will be an opportunity for extreme rainfall events at (t 0, t 0 + δt 0). Furthermore from the three models reviewed, the minimum waiting time until the next extreme rainfall will be determined. The result shows that Log Nrmal model is better than Pareto and Gamma model for predicting the next extreme rainfall in South Sulawesi while the Pareto model can not be used.

Differential equations problem solver

CERN Document Server

Arterburn, David R

2012-01-01

REA's Problem Solvers is a series of useful, practical, and informative study guides. Each title in the series is complete step-by-step solution guide. The Differential Equations Problem Solver enables students to solve difficult problems by showing them step-by-step solutions to Differential Equations problems. The Problem Solvers cover material ranging from the elementary to the advanced and make excellent review books and textbook companions. They're perfect for undergraduate and graduate studies.The Differential Equations Problem Solver is the perfect resource for any class, any exam, and

Psychopathology in difficult asthma

NARCIS (Netherlands)

Prins, L.C.; van Son, M.J.M.; Keimpema, A.R.; van Ranst, D; Pommer, A; Meijer, J.W.; Pop, V.J.M.

2015-01-01

OBJECTIVE: Within the asthma population, difficult asthma (DA) is a severe condition in which patients present with frequent exacerbations, hospitalizations and emergency room visits. The identification and treatment of psychopathology is included in the management of DA. Psychopathology is supposed

Support of the extremal measure in a vector equilibrium problem

International Nuclear Information System (INIS)

Lapik, M A

2006-01-01

A generalization of the Mhaskar-Saff functional is obtained for a vector equilibrium problem with an external field. As an application, the supports of the equilibrium measures are found in a special vector equilibrium problem with Nikishin matrix.

Diversity of life. Effects of power generation and transmission on biodiversity difficult to assess

Energy Technology Data Exchange (ETDEWEB)

Hongisto, M.; Nikula, A.

1996-11-01

Scientific theories do not necessarily enable us to forecast the consequences of our actions on wildlife. Presumably, nature is able to adapt to environmental changes through variations on the genetic, species and ecosystem level; i.e. by means of biodiversity. The first studies conducted within the electricity sector show that the effects of emissions form an individual power plant on biodiversity are extremely difficult to assess because of long-range dispersion of the emission and many other factors simultaneously acting on the environment. Some concrete information about the impact of power transmission lines on biodiversity was obtained. These effects were primarily reversible. Some transmission line zones may even have favourable effects on biodiversity and on the living conditions of certain endangered species. (orig.)

Diversity of life. Effects of power generation and transmission on biodiversity difficult to assess

International Nuclear Information System (INIS)

Hongisto, M.; Nikula, A.

1996-01-01

Scientific theories do not necessarily enable us to forecast the consequences of our actions on wildlife. Presumably, nature is able to adapt to environmental changes through variations on the genetic, species and ecosystem level; i.e. by means of biodiversity. The first studies conducted within the electricity sector show that the effects of emissions form an individual power plant on biodiversity are extremely difficult to assess because of long-range dispersion of the emission and many other factors simultaneously acting on the environment. Some concrete information about the impact of power transmission lines on biodiversity was obtained. These effects were primarily reversible. Some transmission line zones may even have favourable effects on biodiversity and on the living conditions of certain endangered species. (orig.)

Validated questionnaires heighten detection of difficult asthma comorbidities.

Science.gov (United States)

Radhakrishna, Naghmeh; Tay, Tunn Ren; Hore-Lacy, Fiona; Stirling, Robert; Hoy, Ryan; Dabscheck, Eli; Hew, Mark

2017-04-01

Multiple extra-pulmonary comorbidities contribute to difficult asthma, but their diagnosis can be challenging and time consuming. Previous data on comorbidity detection have focused on clinical assessment, which may miss certain conditions. We aimed to locate relevant validated screening questionnaires to identify extra-pulmonary comorbidities that contribute to difficult asthma, and evaluate their performance during a difficult asthma evaluation. MEDLINE was searched to identify key extra-pulmonary comorbidities that contribute to difficult asthma. Screening questionnaires were chosen based on ease of use, presence of a cut-off score, and adequate validation to help systematically identify comorbidities. In a consecutive series of 86 patients referred for systematic evaluation of difficult asthma, questionnaires were administered prior to clinical consultation. Six difficult asthma comorbidities and corresponding screening questionnaires were found: sinonasal disease (allergic rhinitis and chronic rhinosinusitis), vocal cord dysfunction, dysfunctional breathing, obstructive sleep apnea, anxiety and depression, and gastro-oesophageal reflux disease. When the questionnaires were added to the referring clinician's impression, the detection of all six comorbidities was significantly enhanced. The average time for questionnaire administration was approximately 40 minutes. The use of validated screening questionnaires heightens detection of comorbidities in difficult asthma. The availability of data from a battery of questionnaires prior to consultation can save time and allow clinicians to systematically assess difficult asthma patients and to focus on areas of particular concern. Such an approach would ensure that all contributing comorbidities have been addressed before significant treatment escalation is considered.

Patterns and singular features of extreme fluctuational paths of a periodically driven system

International Nuclear Information System (INIS)

Chen, Zhen; Liu, Xianbin

2016-01-01

Large fluctuations of an overdamped periodically driven oscillating system are investigated theoretically and numerically in the limit of weak noise. Optimal paths fluctuating to certain point are given by statistical analysis using the concept of prehistory probability distribution. The validity of statistical results is verified by solutions of boundary value problem. Optimal paths are found to change topologically when terminating points lie at opposite side of a switching line. Patterns of extreme paths are plotted through a proper parameterization of Lagrangian manifold having complicated structures. Several extreme paths to the same point are obtained by multiple solutions of boundary value solutions. Actions along various extreme paths are calculated and associated analysis is performed in relation to the singular features of the patterns. - Highlights: • Both extreme and optimal paths are obtained by various methods. • Boundary value problems are solved to ensure the validity of statistical results. • Topological structure of Lagrangian manifold is considered. • Singularities of the pattern of extreme paths are studied.

Relationships and their potential for change developed in difficult type 1 diabetes

DEFF Research Database (Denmark)

Zoffmann, Vibeke; Kirkevold, Marit

2007-01-01

Few researchers have explored how relationships between patients and providers might change problem solving in clinical practice. The authors used grounded theory to study dyads of 11 people with diabetes and poor glycemic control, and 8 nurses interacting in diabetes teams. Relational Potential...... for Change was identified as a core category that involved three types of relationships. Professionals mostly shifted between less effective relationships characterized by I-you-distant provider dominance and I-you-blurred sympathy. Although rarely seen, a third relationship, I-you-sorted mutuality proved...... more effective than the others in exploiting the Relational Potential for Change. The three types of relationship differed in (a) scope of problem solving, (b) the roles assigned to the patient and the professionals, (c) use of difficult feelings and different points of view, and (d) quality...

Dynamical properties and extremes of Northern Hemisphere climate fields over the past 60 years

Directory of Open Access Journals (Sweden)

D. Faranda

2017-12-01

Full Text Available Atmospheric dynamics are described by a set of partial differential equations yielding an infinite-dimensional phase space. However, the actual trajectories followed by the system appear to be constrained to a finite-dimensional phase space, i.e. a strange attractor. The dynamical properties of this attractor are difficult to determine due to the complex nature of atmospheric motions. A first step to simplify the problem is to focus on observables which affect – or are linked to phenomena which affect – human welfare and activities, such as sea-level pressure, 2 m temperature, and precipitation frequency. We make use of recent advances in dynamical systems theory to estimate two instantaneous dynamical properties of the above fields for the Northern Hemisphere: local dimension and persistence. We then use these metrics to characterize the seasonality of the different fields and their interplay. We further analyse the large-scale anomaly patterns corresponding to phase-space extremes – namely time steps at which the fields display extremes in their instantaneous dynamical properties. The analysis is based on the NCEP/NCAR reanalysis data, over the period 1948–2013. The results show that (i despite the high dimensionality of atmospheric dynamics, the Northern Hemisphere sea-level pressure and temperature fields can on average be described by roughly 20 degrees of freedom; (ii the precipitation field has a higher dimensionality; and (iii the seasonal forcing modulates the variability of the dynamical indicators and affects the occurrence of phase-space extremes. We further identify a number of robust correlations between the dynamical properties of the different variables.

Chronic Expanding Hematoma in the Extremities: A Clinical Problem of Adhesion to the Surrounding Tissues

Science.gov (United States)

Okamoto, Takeshi; Matsuda, Shuichi

2017-01-01

Chronic expanding hematoma is characterized by continuous growth of a blood collection. We analyzed the clinical features of 7 patients with chronic expanding hematomas in the extremities, with an average age of 65.6 years. All lesions occurred in the lower extremities, with 4 seen in the thigh and 3 in the knee region. Six patients had subcutaneous hematomas, while 1 was deep-seated in the thigh. The magnetic resonance features of the lesion were compatible with those of a standard hematoma. A low signal intensity on T1- and T2-weighted imaging at the pseudocapsule was also characteristic. Cystic features were seen in 5 of 7 patients. All lesions were resected together with their pseudocapsule. In the subcutaneous lesions, it was necessary to resect adherent fascia, with or without involved skin. In the deep-seated thigh lesion, the common peroneal nerve was completely adherent to the pseudocapsule, a phenomenon from absence of the common peroneal nerve which appeared after resection. Chronic expanding hematomas of the extremities are predominantly located in the subcutaneous tissue of the lower extremity. The surrounding pseudocapsule is adherent to the adjacent tissues, and clinicians must be aware of this, especially when resecting a deep-seated lesion. PMID:28642872

Chronic Expanding Hematoma in the Extremities: A Clinical Problem of Adhesion to the Surrounding Tissues

Directory of Open Access Journals (Sweden)

Akio Sakamoto

2017-01-01

Full Text Available Chronic expanding hematoma is characterized by continuous growth of a blood collection. We analyzed the clinical features of 7 patients with chronic expanding hematomas in the extremities, with an average age of 65.6 years. All lesions occurred in the lower extremities, with 4 seen in the thigh and 3 in the knee region. Six patients had subcutaneous hematomas, while 1 was deep-seated in the thigh. The magnetic resonance features of the lesion were compatible with those of a standard hematoma. A low signal intensity on T1- and T2-weighted imaging at the pseudocapsule was also characteristic. Cystic features were seen in 5 of 7 patients. All lesions were resected together with their pseudocapsule. In the subcutaneous lesions, it was necessary to resect adherent fascia, with or without involved skin. In the deep-seated thigh lesion, the common peroneal nerve was completely adherent to the pseudocapsule, a phenomenon from absence of the common peroneal nerve which appeared after resection. Chronic expanding hematomas of the extremities are predominantly located in the subcutaneous tissue of the lower extremity. The surrounding pseudocapsule is adherent to the adjacent tissues, and clinicians must be aware of this, especially when resecting a deep-seated lesion.

On some interconnections between combinatorial optimization and extremal graph theory

Directory of Open Access Journals (Sweden)

Cvetković Dragoš M.

2004-01-01

Full Text Available The uniting feature of combinatorial optimization and extremal graph theory is that in both areas one should find extrema of a function defined in most cases on a finite set. While in combinatorial optimization the point is in developing efficient algorithms and heuristics for solving specified types of problems, the extremal graph theory deals with finding bounds for various graph invariants under some constraints and with constructing extremal graphs. We analyze by examples some interconnections and interactions of the two theories and propose some conclusions.

Some types of difficulty encountered during the simulation of heat exchangers (1961); Quelques types de difficultes rencontrees lors de la simulation des echangeurs (1961)

Energy Technology Data Exchange (ETDEWEB)

Bettembourg, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

After recalling that the simulation of exchangers poses problems which are often difficult to solve, the author points out that these problems appear first of all when the physical phenomena are described in terms of equations. They appear also during the solving of the equations since expressions which are more and more complex can give rise to unstable electronic structures. These difficulties are developed during the analysis of various types of exchangers and in each case the solutions chosen are given. (author) [French] On rappelle que la simulation des echangeurs pose un certain nombre de problemes souvent difficiles a resoudre. Les difficultes apparaissent d'abord lors de la mise en equations des phenomenes physiques; elles apparaissent ensuite au moment de la resolution, car des formulations de plus en plus complexes peuvent donner lieu a des structures electroniques instables. On developpe ces difficultes en faisant l'analyse de quelques types varies d'echangeurs et l'on indique dans chacun des cas les solutions qui ont ete retenues. (auteur)

Violent Extremism, Community-Based Violence Prevention, and Mental Health Professionals.

Science.gov (United States)

Weine, Stevan M; Stone, Andrew; Saeed, Aliya; Shanfield, Stephen; Beahrs, John; Gutman, Alisa; Mihajlovic, Aida

2017-01-01

New community-based initiatives being developed to address violent extremism in the United States are utilizing mental health services and leadership. This article reviews current approaches to preventing violent extremism, the contribution that mental illness and psychosocial problems can make to violent extremism, and the rationale for integrating mental health strategies into preventing violent extremism. The authors describe a community-based targeted violence prevention model and the potential roles of mental health professionals. This model consists of a multidisciplinary team that assesses at-risk individuals with comprehensive threat and behavioral evaluations, arranges for ongoing support and treatment, conducts follow-up evaluations, and offers outreach, education, and resources for communities. This model would enable mental health professionals in local communities to play key roles in preventing violent extremism through their practice and leadership.

The Positive Effect of Resilience on Stress and Business Outcomes in Difficult Work Environments.

Science.gov (United States)

Shatté, Andrew; Perlman, Adam; Smith, Brad; Lynch, Wendy D

2017-02-01

To examine whether resilience has a protective effect in difficult work environments. A survey of 2063 individuals measured individual resilience, stress, burnout, sleep problems, likelihood of depression, job satisfaction, intent to quit, absences, and productivity. It also measured work characteristics: job demands, job influence, and social support. Multivariate and logistic regression models examined the main effects and interactions of resilience and job characteristics. High strain work environments (high demand, low influence, and low support) have an unfavorable effect on all outcomes. Resilience has a protective effect on all outcomes. For stress, burnout, and sleep, higher resilience has a more protective effect under low-strain conditions. For depression, absence and productivity, resilience has a more protective effect when job strain is high. Workers with high resilience have better outcomes in difficult work environments.

Modern architectures for intelligent systems: reusable ontologies and problem-solving methods.

Science.gov (United States)

Musen, M A

1998-01-01

When interest in intelligent systems for clinical medicine soared in the 1970s, workers in medical informatics became particularly attracted to rule-based systems. Although many successful rule-based applications were constructed, development and maintenance of large rule bases remained quite problematic. In the 1980s, an entire industry dedicated to the marketing of tools for creating rule-based systems rose and fell, as workers in medical informatics began to appreciate deeply why knowledge acquisition and maintenance for such systems are difficult problems. During this time period, investigators began to explore alternative programming abstractions that could be used to develop intelligent systems. The notions of "generic tasks" and of reusable problem-solving methods became extremely influential. By the 1990s, academic centers were experimenting with architectures for intelligent systems based on two classes of reusable components: (1) domain-independent problem-solving methods-standard algorithms for automating stereotypical tasks--and (2) domain ontologies that captured the essential concepts (and relationships among those concepts) in particular application areas. This paper will highlight how intelligent systems for diverse tasks can be efficiently automated using these kinds of building blocks. The creation of domain ontologies and problem-solving methods is the fundamental end product of basic research in medical informatics. Consequently, these concepts need more attention by our scientific community.

Extreme hydronephrosis due to uretropelvic junction obstruction in infant (case report).

Science.gov (United States)

Krzemień, Grażyna; Szmigielska, Agnieszka; Bombiński, Przemysław; Barczuk, Marzena; Biejat, Agnieszka; Warchoł, Stanisław; Dudek-Warchoł, Teresa

2016-01-01

Hydronephrosis is the one of the most common congenital abnormalities of urinary tract. The left kidney is more commonly affected than the right side and is more common in males. To determine the role of ultrasonography, renal dynamic scintigraphy and lowerdose computed tomography urography in preoperative diagnostic workup of infant with extreme hydronephrosis. We presented the boy with antenatally diagnosed hydronephrosis. In serial, postnatal ultrasonography, renal scintigraphy and computed tomography urography we observed slightly declining function in the dilated kidney and increasing pelvic dilatation. Pyeloplasty was performed at the age of four months with good result. Results of ultrasonography and renal dynamic scintigraphy in child with extreme hydronephrosis can be difficult to asses, therefore before the surgical procedure a lower-dose computed tomography urography should be performed.

Lectures on mathematical theory of extremum problems

CERN Document Server

1972-01-01

The author of this book, Igor' Vladimirovich Girsanov, was one of the first mathematicians to study general extremum problems and to realize the feasibility and desirability of a unified theory of extremal problems, based on a functional­ analytic approach. He actively advocated this view, and his special course, given at the Faculty of Mechanics and Mathematics of the Moscow State University in 1963 and 1964, was apparently the first systematic exposition of a unified approach to the theory of extremal problems. This approach was based on the ideas of Dubovitskii and Milyutin [1]. The general theory of extremal problems has developed so intensely during the past few years that its basic concepts may now be considered finalized. Nevertheless, as yet the basic results of this new field of mathematics have not been presented in a form accessible to a wide range of readers. (The profound paper of Dubovitskii and Milyutin [2] can hardly be recommended for a first study of the theory, since, in particular, it doe...

A new extremity dosemeter for beta and gamma radiation

International Nuclear Information System (INIS)

Heinzelmann, M.; Pagenkamper, M.

1988-01-01

An extremity dosemeter developed at the Juelich Nuclear Research Centre is very well suited for the precise and energy-independent measurement of the skin dose generated by beta or gamma radiation. This is also confirmed by the results of this intercomparison programme. The dosemeter contains three TLDs of LiF in Teflon mounted behind a window of 0.9 mg/cm 2 . The great advantage of this dosemeter is three TLD's enabling statements about the radiation quality. However, the dosemeter has two disadvantages The dosemeter is complicated to manufacture. A very thin plastic foil of 0.9 mg/cm 2 must be attached to a support. This work is difficult and time-consuming and cannot be automated. The window in front of the TLD is not sturdy enough and is occasionally destroyed when the dosemeter is being worn. These two disadvantages prevent this extremity dosemeter from being used more frequently. For this reason, work was begun on developing a new extremity dosemeter without these two disadvantages. The great advantage of the previous dosemeter of obtaining statements about the type of radiation with the aid of readings from three TLD's was to be retained. The improved extremity dosemeter has a more sturdy and thicker window with a similar response as the previous dosemeter with a thinner window

Non-Stationary Dependence Structures for Spatial Extremes

KAUST Repository

Huser, Raphaël

2016-03-03

Max-stable processes are natural models for spatial extremes because they provide suitable asymptotic approximations to the distribution of maxima of random fields. In the recent past, several parametric families of stationary max-stable models have been developed, and fitted to various types of data. However, a recurrent problem is the modeling of non-stationarity. In this paper, we develop non-stationary max-stable dependence structures in which covariates can be easily incorporated. Inference is performed using pairwise likelihoods, and its performance is assessed by an extensive simulation study based on a non-stationary locally isotropic extremal t model. Evidence that unknown parameters are well estimated is provided, and estimation of spatial return level curves is discussed. The methodology is demonstrated with temperature maxima recorded over a complex topography. Models are shown to satisfactorily capture extremal dependence.

How extreme is enough to cause a threshold response of ecosystem

Science.gov (United States)

Niu, S.; Zhang, F.; Yang, Q.; Song, B.; Sun, J.

2017-12-01

Precipitation is a primary determinant of terrestrial ecosystem productivity over much of the globe. Recent studies have shown asymmetric or threshold responses of ecosystem productivity to precipitation gradient. However, it's not clear how extreme is enough to cause a threshold response of ecosystem. We conducted a global meta-analysis of precipitation experiments, a site level precipitation gradient experiment, and a remote sensing data mining on the relationship between precipitation extreme vs NDVI extreme. The meta-analysis shows that ANPP, BNPP, NEE, and other carbon cycle variables, showed similar response magnitudes to either precipitation increase or decrease when precipitation levels were normalized to the medium value of treatments (40%) across all the studies. Overall, the response ratios of these variables were linearly correlated with changes in precipitation amounts and soil water content. In the field gradient study with treatments of 1/12, 1/8. 1/4, 1/2, control, and 5/4 of ambient precipitation, the threshold of NPP, SR, NEE occurred when precipitation was reduced to the level of 1/8-1/12 of ambient precipitation. This means that only extreme drought can induce a threshold response of ecosystem. The regional remote sensing data showed that climate extremes with yearly low precipitation from 1982 to 2013 rarely cause extreme responses of vegetation, further suggesting that it is very difficult to detect threshold responses to natural climatic fluctuation. Our three studies together indicate that asymmetrical responses of vegetation to precipitation are likely detected, but only in very extreme precipitation events.

Simulating variable source problems via post processing of individual particle tallies

International Nuclear Information System (INIS)

Bleuel, D.L.; Donahue, R.J.; Ludewigt, B.A.; Vujic, J.

2000-01-01

Monte Carlo is an extremely powerful method of simulating complex, three dimensional environments without excessive problem simplification. However, it is often time consuming to simulate models in which the source can be highly varied. Similarly difficult are optimization studies involving sources in which many input parameters are variable, such as particle energy, angle, and spatial distribution. Such studies are often approached using brute force methods or intelligent guesswork. One field in which these problems are often encountered is accelerator-driven Boron Neutron Capture Therapy (BNCT) for the treatment of cancers. Solving the reverse problem of determining the best neutron source for optimal BNCT treatment can be accomplished by separating the time-consuming particle-tracking process of a full Monte Carlo simulation from the calculation of the source weighting factors which is typically performed at the beginning of a Monte Carlo simulation. By post-processing these weighting factors on a recorded file of individual particle tally information, the effect of changing source variables can be realized in a matter of seconds, instead of requiring hours or days for additional complete simulations. By intelligent source biasing, any number of different source distributions can be calculated quickly from a single Monte Carlo simulation. The source description can be treated as variable and the effect of changing multiple interdependent source variables on the problem's solution can be determined. Though the focus of this study is on BNCT applications, this procedure may be applicable to any problem that involves a variable source

Extremal black holes in N=2 supergravity

NARCIS (Netherlands)

Katmadas, S.

2011-01-01

An explanation for the entropy of black holes has been an outstanding problem in recent decades. A special case where this is possible is that of extremal black holes in N=2 supergravity in four and five dimensions. The best developed case is for black holes preserving some supersymmetry (BPS),

The Difficult Chore of Measuring Coordination by EXAFS

International Nuclear Information System (INIS)

Ravel, B.; Kelly, S. D.

2007-01-01

Neither the theory nor the interpretation of Extended X-Ray-Absorption Fine-Structure (EXAFS) spectroscopy requires assumptions of crystalline symmetry or periodicity. As a result, EXAFS is a tool applied to a wide range of scientific disciplines and to a wide variety of experimental systems. A simple enumeration of the atoms in the coordination environment of the absorber is often the primary goal of an EXAFS experiment. There are, however, a number of pitfalls in the way of an accurate determination of coordination number (CN). These include statistical limitations of the EXAFS fitting problem, empirical effects due to sample preparation, and the assumptions made about the physical structure surrounding the absorber in the course of data analysis. In this paper we examine several of these pitfalls and their effects upon the determination of CN. Where possible, we offer suggestions for avoiding or mitigating the pitfalls. We hope this paper will help guide the general EXAFS practitioner through the difficult chore of accurately determining CN

Making marketing difficult

DEFF Research Database (Denmark)

Meyer, Gitte

2005-01-01

embraced by the market-place, while maintaining the old scientific alienation from political life. The case is made that modern science was born ambiguous towards the market-place, and that such ambivalence - relating to different interpretations of the idea of knowledge as a common good - is still...... to be encountered among scientists. Drawing on series of interviews with scientists from bioscience and biotechnology it is argued that, on the one hand, scientists are into marketing and PR exercises; but, on the other hand, they also voice a demand that journalists should make such marketing difficult...

Physiotherapy in the postpartum problems

Directory of Open Access Journals (Sweden)

Witold Słomko

2017-04-01

Full Text Available Female after childbirth recovering at different rates, in theory, it is assumed that the confinement takes from 6 to 8 weeks. At this time maternal should return of the condition before pregnancy and childbirth. Sometimes that the return to full fitness is difficult, because of the problems typical for the postpartum. This article presents physiotherapeutic methods are effective in treating: diastasis of the rectus muscle of abdomen, stretch marks, difficult  healing scars after a cesarean section, lactating problems, incontinence. Appropriate treatment results prevention of these symptoms, although if they appear, it helps to fight them down. Kinesitherapy and physical therapy are used in the treatment. Also can be used massage and kinesiotaping.

Acceptance issues for large items and difficult waste

International Nuclear Information System (INIS)

Palmer, J.; Lock, Peter

2002-01-01

Peter Lock described some particular cases which had given rise to difficult acceptance issues at NIREX, ranging from large size items to the impacts of chemicals used during decontamination on the mobility of radionuclides in a disposal facility: The UK strategy for intermediate level and certain low level radioactive waste disposal is based on production of cementitious waste-forms packaged in a standard range of containers as follows: 500 litre Drum - the normal container for most operational ILW (0.8 m diameter x 1.2 m high); 3 m"3 Box - a larger container for solid wastes (1.72 m x 1.72 m plan x 1.2 m high); 3 m"3 Drum - a larger container for in-drum mixing and immobilisation of sludge waste-forms (1.72 m diameter x 1.2 m high); 4 m Box - for large items of waste, especially from decommissioning (4.0 m x 2.4 m plan x 2.2 m high); 2 m LLW Box - for higher-density wastes (2.0 m x 2.4 m plan x 2.2 m high). In addition the majority of LLW is packaged by supercompaction followed by grouting in modified ISO freight containers (6 m x 2.5 m x 2.5 m). Some wastes do not fit easily into this strategy. These wastes include: very large items, (too big for the 4 m box) which, if dealt with whole, pose transport and disposal problems. These items are discussed further in Section 2; waste whose characteristics make packaging difficult. Such wastes are described in more detail in Section 3

The optimal graph partitioning problem

DEFF Research Database (Denmark)

Sørensen, Michael Malmros; Holm, Søren

1993-01-01

. This problem can be formulated as a MILP, which turns out to be completely symmetrical with respect to the p classes, and the gap between the relaxed LP solution and the optimal solution is the largest one possible. These two properties make it very difficult to solve even smaller problems. In this paper...

LIHTC Difficult to Develop Areas

Data.gov (United States)

Department of Housing and Urban Development — A Difficult Development Area (DDA) for the Low Income Housing Tax Credit program is an area designated by the U.S. Department of Housing and Urban Development (HUD)...

Wind simulation for extreme and fatigue loads

Energy Technology Data Exchange (ETDEWEB)

Nielsen, M.; Larsen, G.C.; Mann, J.; Ott, S.; Hansen, K.S.; Pedersen, B.J.

2004-01-01

Measurements of atmospheric turbulence have been studied and found to deviate from a Gaussian process, in particular regarding the velocity increments over small time steps, where the tails of the pdf are exponential rather than Gaussian. Principles for extreme event counting and the occurrence of cascading events are presented. Empirical extreme statistics agree with Rices exceedence theory, when it is assumed that the velocity and its time derivative are independent. Prediction based on the assumption that the velocity is a Gaussian process underpredicts the rate of occurrence of extreme events by many orders of magnitude, mainly because the measured pdf is non-Gaussian. Methods for simulation of turbulent signals have been developed and their computational efficiency are considered. The methods are applicable for multiple processes with individual spectra and probability distributions. Non-Gaussian processes are simulated by the correlation-distortion method. Non-stationary processes are obtained by Bezier interpolation between a set of stationary simulations with identical random seeds. Simulation of systems with some signals available is enabled by conditional statistics. A versatile method for simulation of extreme events has been developed. This will generate gusts, velocity jumps, extreme velocity shears, and sudden changes of wind direction. Gusts may be prescribed with a specified ensemble average shape, and it is possible to detect the critical gust shape for a given construction. The problem is formulated as the variational problem of finding the most probable adjustment of a standard simulation of a stationary Gaussian process subject to relevant event conditions, which are formulated as linear combination of points in the realization. The method is generalized for multiple correlated series, multiple simultaneous conditions, and 3D fields of all velocity components. Generalization are presented for a single non-Gaussian process subject to relatively

Tribal Colleges: The Original Extreme Makeover Experts

Science.gov (United States)

Powless, Donna

2015-01-01

In this article, the author states "our experience with education is a prime example in proving we are experts at problem-solving and are the originators of the extreme makeover." Educational institutions were introduced to the Native people in an outrageous manner--often as a mask for assimilating American Indians, routinely resulting…

Block Model Approach in Problem Solving: Effects on Problem Solving Performance of the Grade V Pupils in Mathematics

Science.gov (United States)

de Guzman, Niño Jose P.; Belecina, Rene R.

2012-01-01

The teaching of mathematics involves problem solving skills which prove to be difficult on the part of the pupils due to misrepresentation of the word problems. Oftentimes, pupils tend to represent the phrase "more than" as addition and the word difference as "- ". This paper aims to address the problem solving skills of grade…

Difficult to control atopic dermatitis

NARCIS (Netherlands)

U. Darsow (U.); A. Wollenberg (A.); D. Simon; A. Taieb; T. Werfel; A.P. Oranje (Arnold); C. Gelmetti (C.); Ã. Svensson (Ãke); M. Deleuran (M.); A.M. Calza; F. Giusti; J. Lübbe (Jann); S. Seidenari (Stefania); J. Ring (J.)

2013-01-01

textabstractDifficult to control atopic dermatitis (AD) presents a therapeutic challenge and often requires combinations of topical and systemic treatment. Anti-inflammatory treatment of severe AD most commonly includes topical glucocorticosteroids and topical calcineurin antagonists used for

How Difficult It Is to Be God

DEFF Research Database (Denmark)

Wilson, Fiona

2014-01-01

Book review of Carlos Iván Degregori, How Difficult It Is to Be God: Shining Path's Politics of War in Peru,1980–1999 (Madison, WI: University of Wisconsin Press, 2012)......Book review of Carlos Iván Degregori, How Difficult It Is to Be God: Shining Path's Politics of War in Peru,1980–1999 (Madison, WI: University of Wisconsin Press, 2012)...

Determining the Extremes of the Cellular NAD(H) Level by Using an Escherichia coli NAD+-Auxotrophic Mutant ▿

OpenAIRE

Zhou, Yongjin; Wang, Lei; Yang, Fan; Lin, Xinping; Zhang, Sufang; Zhao, Zongbao K.

2011-01-01

NAD (NAD+) and its reduced form (NADH) are omnipresent cofactors in biological systems. However, it is difficult to determine the extremes of the cellular NAD(H) level in live cells because the NAD+ level is tightly controlled by a biosynthesis regulation mechanism. Here, we developed a strategy to determine the extreme NAD(H) levels in Escherichia coli cells that were genetically engineered to be NAD+ auxotrophic. First, we expressed the ntt4 gene encoding the NAD(H) transporter in the E. co...

Psychopathology in difficult asthma : Review

NARCIS (Netherlands)

Prins, L.C.J.; van Son, M.A.C.; van Keimpema, A.R.J.; van Ranst, D.; Antonissen-Pommer, A.M.; Meijer, J.W.G.; Pop, V.J.M.

2015-01-01

Objective: Within the asthma population, difficult asthma (DA) is a severe condition in which patients present with frequent exacerbations, hospitalizations and emergency room visits. The identification and treatment of psychopathology is included in the management of DA. Psychopathology is supposed

Oral to nasal tube exchange under fibroscopic view: a new technique for nasal intubation in a predicted difficult airway.

Science.gov (United States)

Monclus, Enric; Garcés, Antonio; Artés, David; Mabrock, Maged

2008-07-01

For a predicted difficult airway, oral intubation techniques are well established in pediatric anesthesia, but nasotracheal intubation remains a problem. There are many reports concerning this, but the risk of bleeding, added to the lack of cooperation make this procedure difficult and hazardous. We describe a modification of the nasal intubation technique in two stages. First an oral intubation and then exchanging the oral for a nasal tube, in the case of a 13-year-old boy affected by an advanced stage of cherubism. Oral intubation using a laryngeal mask technique has already been reported, but problems appear during the exchange procedure and even more when direct laryngoscopy is impossible. Fiberscopic control of the exchange, and the introduction of a Cook Exchange Catheter into the trachea through the oral tube before withdrawal, permits oxygenation of the patient and acts as a guide for oral tube reintroduction if required.

Assessment of vertical transfer in problem solving: Mapping the problem design space

Science.gov (United States)

Von Korff, Joshua; Hu, Dehui; Rebello, N. Sanjay

2012-02-01

In schema-based theories of cognition, vertical transfer occurs when a learner constructs a new schema to solve a transfer task or chooses between several possible schemas. Vertical transfer is interesting to study, but difficult to measure. Did the student solve the problem using the desired schema or by an alternative method? Perhaps the problem cued the student to use certain resources without knowing why? In this paper, we consider some of the threats to validity in problem design. We provide a theoretical framework to explain the challenges faced in designing vertical transfer problems, and we contrast these challenges with horizontal transfer problem design. We have developed this framework from a set of problems that we tested on introductory mechanics students, and we illustrate the framework using one of the problems.

Cause and Properties of the Extreme Space Weather Event of 2012 July 23

Science.gov (United States)

Liu, Y. D.; Luhmann, J. G.; Kajdic, P.; Kilpua, E.; Lugaz, N.; Nitta, N.; Lavraud, B.; Bale, S. D.; Farrugia, C. J.; Galvin, A. B.

2013-12-01

Extreme space weather refers to extreme conditions in space driven by solar eruptions and subsequent disturbances in interplanetary space, or otherwise called solar superstorms. Understanding extreme space weather events is becoming ever more vital, as the vulnerability of our society and its technological infrastructure to space weather has increased dramatically. Instances of extreme space weather, however, are very rare by definition and therefore are difficult to study. Here we report and investigate an extreme event, which occurred on 2012 July 23 with a maximum speed of about 3050 km/s near the Sun. This event, with complete modern remote sensing and in situ observations from multiple vantage points, provides an unprecedented opportunity to study the cause and consequences of extreme space weather. It produced a superfast shock with a peak solar wind speed of 2246 km/s and a superstrong magnetic cloud with a peak magnetic field of 109 nT observed near 1 AU at STEREO A. The record solar wind speed and magnetic field would produce a record geomagnetic storm since the space era with a minimum Dst of -1200 - -600 nT, if this event hit the Earth. We demonstrate how successive coronal mass ejections (CMEs) can be enhanced into a solar superstorm as they interact en route from the Sun to 1 AU. These results not only provide a benchmark for studies of extreme space weather, but also present a new view of how an extreme space weather event can be generated from usual solar eruptions.

Examining problem solving in physics-intensive Ph.D. research

Directory of Open Access Journals (Sweden)

Anne E. Leak

2017-07-01

Full Text Available Problem-solving strategies learned by physics undergraduates should prepare them for real-world contexts as they transition from students to professionals. Yet, graduate students in physics-intensive research face problems that go beyond problem sets they experienced as undergraduates and are solved by different strategies than are typically learned in undergraduate coursework. This paper expands the notion of problem solving by characterizing the breadth of problems and problem-solving processes carried out by graduate students in physics-intensive research. We conducted semi-structured interviews with ten graduate students to determine the routine, difficult, and important problems they engage in and problem-solving strategies they found useful in their research. A qualitative typological analysis resulted in the creation of a three-dimensional framework: context, activity, and feature (that made the problem challenging. Problem contexts extended beyond theory and mathematics to include interactions with lab equipment, data, software, and people. Important and difficult contexts blended social and technical skills. Routine problem activities were typically well defined (e.g., troubleshooting, while difficult and important ones were more open ended and had multiple solution paths (e.g., evaluating options. In addition to broadening our understanding of problems faced by graduate students, our findings explore problem-solving strategies (e.g., breaking down problems, evaluating options, using test cases or approximations and characteristics of successful problem solvers (e.g., initiative, persistence, and motivation. Our research provides evidence of the influence that problems students are exposed to have on the strategies they use and learn. Using this evidence, we have developed a preliminary framework for exploring problems from the solver’s perspective. This framework will be examined and refined in future work. Understanding problems

Examining problem solving in physics-intensive Ph.D. research

Science.gov (United States)

Leak, Anne E.; Rothwell, Susan L.; Olivera, Javier; Zwickl, Benjamin; Vosburg, Jarrett; Martin, Kelly Norris

2017-12-01

Problem-solving strategies learned by physics undergraduates should prepare them for real-world contexts as they transition from students to professionals. Yet, graduate students in physics-intensive research face problems that go beyond problem sets they experienced as undergraduates and are solved by different strategies than are typically learned in undergraduate coursework. This paper expands the notion of problem solving by characterizing the breadth of problems and problem-solving processes carried out by graduate students in physics-intensive research. We conducted semi-structured interviews with ten graduate students to determine the routine, difficult, and important problems they engage in and problem-solving strategies they found useful in their research. A qualitative typological analysis resulted in the creation of a three-dimensional framework: context, activity, and feature (that made the problem challenging). Problem contexts extended beyond theory and mathematics to include interactions with lab equipment, data, software, and people. Important and difficult contexts blended social and technical skills. Routine problem activities were typically well defined (e.g., troubleshooting), while difficult and important ones were more open ended and had multiple solution paths (e.g., evaluating options). In addition to broadening our understanding of problems faced by graduate students, our findings explore problem-solving strategies (e.g., breaking down problems, evaluating options, using test cases or approximations) and characteristics of successful problem solvers (e.g., initiative, persistence, and motivation). Our research provides evidence of the influence that problems students are exposed to have on the strategies they use and learn. Using this evidence, we have developed a preliminary framework for exploring problems from the solver's perspective. This framework will be examined and refined in future work. Understanding problems graduate students

Terminological and Definitional Problems of Deficit and Debt in the Polish and EU Law of Public Finance

Directory of Open Access Journals (Sweden)

Ewa Lotko

2016-06-01

Full Text Available In the Polish and the EU public finances law there are serious terminological difficulties concerning the deficit and the debt. They arise first from the terminological chaos in this field and second from the parallel application of the EU and the Polish methodology of calculating of deficit and debt. Thus, the paper aims to explain the terminological and definitional problems of deficit and debt in the public finances law using unobtrusive research consisting of the detailed analysis of the Polish and EU legislation. Although there is no doubt that it would be desirable to order the applied terms, in the current legal situation, it would be extremely difficult, as it would require the changes to the Constitution, laws, and modification of translations of UE acts. The solution to the problem, presenting additional advantages, could consist of full transition to the EU methodology by the renouncement from the Polish methodology.

Solving Classical Insight Problems without Aha! Experience: 9 Dot, 8 Coin, and Matchstick Arithmetic Problems

Science.gov (United States)

Danek, Amory H.; Wiley, Jennifer; Öllinger, Michael

2016-01-01

Insightful problem solving is a vital part of human thinking, yet very difficult to grasp. Traditionally, insight has been investigated by using a set of established "insight tasks," assuming that insight has taken place if these problems are solved. Instead of assuming that insight takes place during every solution of the 9 Dot, 8 Coin,…

Metacognition: Student Reflections on Problem Solving

Science.gov (United States)

Wismath, Shelly; Orr, Doug; Good, Brandon

2014-01-01

Twenty-first century teaching and learning focus on the fundamental skills of critical thinking and problem solving, creativity and innovation, and collaboration and communication. Metacognition is a crucial aspect of both problem solving and critical thinking, but it is often difficult to get students to engage in authentic metacognitive…

A new Class of Extremal Composites

DEFF Research Database (Denmark)

Sigmund, Ole

2000-01-01

microstructure belonging to the new class of composites has maximum bulk modulus and lower shear modulus than any previously known composite. Inspiration for the new composite class comes from a numerical topology design procedure which solves the inverse homogenization problem of distributing two isotropic......The paper presents a new class of two-phase isotropic composites with extremal bulk modulus. The new class consists of micro geometrics for which exact solutions can be proven and their bulk moduli are shown to coincide with the Hashin-Shtrikman bounds. The results hold for two and three dimensions...... and for both well- and non-well-ordered isotropic constituent phases. The new class of composites constitutes an alternative to the three previously known extremal composite classes: finite rank laminates, composite sphere assemblages and Vigdergauz microstructures. An isotropic honeycomb-like hexagonal...

Guidelines and algorithms for managing the difficult airway.

Science.gov (United States)

Gómez-Ríos, M A; Gaitini, L; Matter, I; Somri, M

2018-01-01

The difficult airway constitutes a continuous challenge for anesthesiologists. Guidelines and algorithms are key to preserving patient safety, by recommending specific plans and strategies that address predicted or unexpected difficult airway. However, there are currently no "gold standard" algorithms or universally accepted standards. The aim of this article is to present a synthesis of the recommendations of the main guidelines and difficult airway algorithms. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics*

OpenAIRE

Mushambi, M C; Kinsella, S M; Popat, M; Swales, H; Ramaswamy, K K; Winton, A L; Quinn, A C

2015-01-01

The Obstetric Anaesthetists' Association and Difficult Airway Society have developed the first national obstetric guidelines for the safe management of difficult and failed tracheal intubation during general anaesthesia. They comprise four algorithms and two tables. A master algorithm provides an overview. Algorithm 1 gives a framework on how to optimise a safe general anaesthetic technique in the obstetric patient, and emphasises: planning and multidisciplinary communication; how to prevent ...

How to manage a child with difficult asthma?

Science.gov (United States)

Saglani, Sejal; Fleming, Louise

2016-08-01

Children with difficult asthma have significant morbidity and fail to achieve asthma control despite being prescribed high dose maintenance treatment. If control remains poor after diagnostic confirmation, detailed assessments of the reasons for asthma being difficult-to-control are needed. Underlying modifiable factors including non-adherence to medication, persistent environmental exposures that trigger asthma symptoms and psychosocial factors contribute to poor control in these patients. The focus of this review is to provide a practical approach to the diagnosis and management of difficult asthma including an overview of long term assessments to identify potential progression to true, severe asthma. A multi-disciplinary team is critical to enable modifiable factors to be identified and addressed. Significant resources are required to manage paediatric difficult asthma optimally and only specialist centres should be tasked with the assessment of these patients. Although this may have an impact on healthcare resources, long term benefits for lung health are significant. Expert commentary: The management of paediatric difficult asthma is not simple and involves numerous professionals with varied expertise. However, if it is not undertaken with the appropriate skills, there is a significant risk of children receiving inappropriate invasive investigations and therapies that will have no impact on morbidity.

Deterring violent extremism in America by utilizing good counter-radicalization practices from abroad: a policy perspective

OpenAIRE

Bonanno, Amy Fires

2017-01-01

Approved for public release; distribution is unlimited The problem of violent extremism is approaching a critical point in America. American government and community leaders must find an effective approach to deterring violent extremism immediately. A national and comprehensive approach to deter violent extremism in America is currently lacking. This comparative policy perspective seeks to determine whether the United Kingdom and Australia have good practices to deter violent extremism tha...

The inverse problem of sensing the mass and force induced by an adsorbate on a beam nanomechanical resonator

Energy Technology Data Exchange (ETDEWEB)

Liu, Yun [Faculty of Information and Automation, Kunming University of Science and Technology, Kunming, Yunnan Province 65005 (China); Zhang, Yin [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190 (China)

2016-06-08

The mass sensing superiority of a micro/nanomechanical resonator sensor over conventional mass spectrometry has been, or at least, is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the analyte/adsorbate mass, many other factors such as position and axial force can also cause the shifts of resonant frequencies. The in-situ measurement of the adsorbate position and axial force is extremely difficult if not impossible, especially when an adsorbate is as small as a molecule or an atom. Extra instruments are also required. In this study, an inverse problem of using three resonant frequencies to determine the mass, position and axial force is formulated and solved. The accuracy of the inverse problem solving method is demonstrated and how the method can be used in the real application of a nanomechanical resonator is also discussed. Solving the inverse problem is helpful to the development and application of mechanical resonator sensor on two things: reducing extra experimental equipments and achieving better mass sensing by considering more factors.

A branch-and-price algorithm for the capacitated facility location problem

DEFF Research Database (Denmark)

Klose, Andreas; Görtz, Simon

2007-01-01

to compute optimal solutions to large or difficult problem instances by means of a branch-and-bound procedure information about such a primal fractional solution can be advantageous. In this paper, a (stabilized) column generation method is, therefore, employed in order to solve a corresponding master...... problem exactly. The column generation procedure is then employed within a branch-and-price algorithm for computing optimal solutions to the CFLP. Computational results are reported for a set of larger and difficult problem instances....

Investigating NARCCAP Precipitation Extremes via Bivariate Extreme Value Theory (Invited)

Science.gov (United States)

Weller, G. B.; Cooley, D. S.; Sain, S. R.; Bukovsky, M. S.; Mearns, L. O.

2013-12-01

We introduce methodology from statistical extreme value theory to examine the ability of reanalysis-drive regional climate models to simulate past daily precipitation extremes. Going beyond a comparison of summary statistics such as 20-year return values, we study whether the most extreme precipitation events produced by climate model simulations exhibit correspondence to the most extreme events seen in observational records. The extent of this correspondence is formulated via the statistical concept of tail dependence. We examine several case studies of extreme precipitation events simulated by the six models of the North American Regional Climate Change Assessment Program (NARCCAP) driven by NCEP reanalysis. It is found that the NARCCAP models generally reproduce daily winter precipitation extremes along the Pacific coast quite well; in contrast, simulation of past daily summer precipitation extremes in a central US region is poor. Some differences in the strength of extremal correspondence are seen in the central region between models which employ spectral nudging and those which do not. We demonstrate how these techniques may be used to draw a link between extreme precipitation events and large-scale atmospheric drivers, as well as to downscale extreme precipitation simulated by a future run of a regional climate model. Specifically, we examine potential future changes in the nature of extreme precipitation along the Pacific coast produced by the pineapple express (PE) phenomenon. A link between extreme precipitation events and a "PE Index" derived from North Pacific sea-surface pressure fields is found. This link is used to study PE-influenced extreme precipitation produced by a future-scenario climate model run.

Working with Child Prostitutes in Thailand: Problems of Practice and Interpretation

Science.gov (United States)

Montgomery, Heather

2007-01-01

Conducting anthropological fieldwork on the emotive issue of child prostitution raises difficult issues for anthropologists and other researchers. This article examines the ethical dilemmas of working with these extremely vulnerable children, focusing on the difference between the researcher's own interpretations and those given by the children…

Statistical analysis and ANN modeling for predicting hydrological extremes under climate change scenarios: the example of a small Mediterranean agro-watershed.

Science.gov (United States)

Kourgialas, Nektarios N; Dokou, Zoi; Karatzas, George P

2015-05-01

The purpose of this study was to create a modeling management tool for the simulation of extreme flow events under current and future climatic conditions. This tool is a combination of different components and can be applied in complex hydrogeological river basins, where frequent flood and drought phenomena occur. The first component is the statistical analysis of the available hydro-meteorological data. Specifically, principal components analysis was performed in order to quantify the importance of the hydro-meteorological parameters that affect the generation of extreme events. The second component is a prediction-forecasting artificial neural network (ANN) model that simulates, accurately and efficiently, river flow on an hourly basis. This model is based on a methodology that attempts to resolve a very difficult problem related to the accurate estimation of extreme flows. For this purpose, the available measurements (5 years of hourly data) were divided in two subsets: one for the dry and one for the wet periods of the hydrological year. This way, two ANNs were created, trained, tested and validated for a complex Mediterranean river basin in Crete, Greece. As part of the second management component a statistical downscaling tool was used for the creation of meteorological data according to the higher and lower emission climate change scenarios A2 and B1. These data are used as input in the ANN for the forecasting of river flow for the next two decades. The final component is the application of a meteorological index on the measured and forecasted precipitation and flow data, in order to assess the severity and duration of extreme events. Copyright © 2015 Elsevier Ltd. All rights reserved.

Convergence of Extreme Value Statistics in a Two-Layer Quasi-Geostrophic Atmospheric Model

Directory of Open Access Journals (Sweden)

Vera Melinda Gálfi

2017-01-01

Full Text Available We search for the signature of universal properties of extreme events, theoretically predicted for Axiom A flows, in a chaotic and high-dimensional dynamical system. We study the convergence of GEV (Generalized Extreme Value and GP (Generalized Pareto shape parameter estimates to the theoretical value, which is expressed in terms of the partial information dimensions of the attractor. We consider a two-layer quasi-geostrophic atmospheric model of the mid-latitudes, adopt two levels of forcing, and analyse the extremes of different types of physical observables (local energy, zonally averaged energy, and globally averaged energy. We find good agreement in the shape parameter estimates with the theory only in the case of more intense forcing, corresponding to a strong chaotic behaviour, for some observables (the local energy at every latitude. Due to the limited (though very large data size and to the presence of serial correlations, it is difficult to obtain robust statistics of extremes in the case of the other observables. In the case of weak forcing, which leads to weaker chaotic conditions with regime behaviour, we find, unsurprisingly, worse agreement with the theory developed for Axiom A flows.

Prevention through policy: Urban macroplastic leakages to the marine environment during extreme rainfall events

OpenAIRE

Axelsson, Charles; van Sebille, Erik

2017-01-01

The leakage of large plastic litter (macroplastics) into the ocean is a major environmental problem. A significant fraction of this leakage originates from coastal cities, particularly during extreme rainfall events. As coastal cities continue to grow, finding ways to reduce this macroplastic leakage is extremely pertinent. Here, we explore why and how coastal cities can reduce macroplastic leakages during extreme rainfall events. Using nine global cities as a basis, we establish that while c...

The Solving of Problems in Chemistry: the more open-ended problems

Science.gov (United States)

Reid, Norman; Yang, Mei-Jung

2002-01-01

Most problem solving in chemistry tends to be algorithmic in nature, while problems in life tend to be very open ended. This paper offers a simple classification of problems and seeks to explore the many factors which may be important in the successful solving of problems. It considers the place of procedures and algorithms. It analyses the role of long-term memory, not only in terms of what is known, but how that knowledge was acquired. It notes the great importance of the limitations of working memory space and the importance of confidence which comes from experience. Finally, various psychological factors are discussed. This paper argues that solving open-ended problems is extremely important in education and that offering learners experience of this in a group work context is a helpful way forward.

Extreme groundwater levels caused by extreme weather conditions - the highest ever measured groundwater levels in Middle Germany and their management

Science.gov (United States)

Reinstorf, F.; Kramer, S.; Koch, T.; Pfützner, B.

2017-12-01

Extreme weather conditions during the years 2009 - 2011 in combination with changes in the regional water management led to maximum groundwater levels in large areas of Germany in 2011. This resulted in extensive water logging, with problems especially in urban areas near rivers, where water logging produced huge problems for buildings and infrastructure. The acute situation still exists in many areas and requires the development of solution concepts. Taken the example of the Elbe-Saale-Region in the Federal State of Saxony-Anhalt, were a pilot research project was carried out, the analytical situation, the development of a management tool and the implementation of a groundwater management concept are shown. The central tool is a coupled water budget - groundwater flow model. In combination with sophisticated multi-scale parameter estimation, a high-resolution groundwater level simulation was carried out. A decision support process with an intensive stakeholder interaction combined with high-resolution simulations enables the development of a management concept for extreme groundwater situations in consideration of sustainable and environmentally sound solutions mainly on the base of passive measures.

Temporal changes in morality attributed to heat extremes for 57 cities in Northeast Asia.

Science.gov (United States)

Lee, Whanhee; Choi, Hayon Michelle; Kim, Dahye; Honda, Yasushi; Guo, Yue-Liang Leon; Kim, Ho

2018-03-01

Recent studies have reported that heat-related mortality decreased by adaptation during decades. However, since the frequency of extreme heat events is increasing, it is difficult to conclude with certainty that the heat mortality burden is decreasing. To examine temporal changes in mortality attributed to heat extremes in Northeast Asia, we collected temperature and mortality data covering the years 1972-2012 from 57 cities of 3 countries (Taiwan, Korea, and Japan) in Northeast Asia. Poisson regression curves were fitted to the data from each city. The temporal changes in heat-mortality association were estimated with a time-varying distributed lag non-linear model. Heat extremes were defined as temperatures greater than the 97.5th percentiles of city-specific average temperatures. Attributable deaths were calculated considering temporal variations in exposure and relative risk. The estimates were then pooled through meta-analysis. The results show that the mortality risk on extreme heat days declined during the study period in all countries. However, as summer temperatures in Japan have shown more heat extremes over time, the mortality risk attributed to heat increased during 2003-2012 (0.32%) compared with 1972-1981 (0.19%). Thus, to assess the total health burden due to heat extremes related to climate change, public health strategies should focus on the temporal variation in heat-mortality association as well as changes in the distribution of heat extremes overtime. Copyright © 2017 Elsevier B.V. All rights reserved.

Distributed Extreme Learning Machine for Nonlinear Learning over Network

Directory of Open Access Journals (Sweden)

Songyan Huang

2015-02-01

Full Text Available Distributed data collection and analysis over a network are ubiquitous, especially over a wireless sensor network (WSN. To our knowledge, the data model used in most of the distributed algorithms is linear. However, in real applications, the linearity of systems is not always guaranteed. In nonlinear cases, the single hidden layer feedforward neural network (SLFN with radial basis function (RBF hidden neurons has the ability to approximate any continuous functions and, thus, may be used as the nonlinear learning system. However, confined by the communication cost, using the distributed version of the conventional algorithms to train the neural network directly is usually prohibited. Fortunately, based on the theorems provided in the extreme learning machine (ELM literature, we only need to compute the output weights of the SLFN. Computing the output weights itself is a linear learning problem, although the input-output mapping of the overall SLFN is still nonlinear. Using the distributed algorithmto cooperatively compute the output weights of the SLFN, we obtain a distributed extreme learning machine (dELM for nonlinear learning in this paper. This dELM is applied to the regression problem and classification problem to demonstrate its effectiveness and advantages.

Progressive problems higher grade physics

CERN Document Server

Kennedy, William

2001-01-01

This book fully covers all three Units studied in Scotland's Higher Grade Physics course, providing a systematic array of problems (from the simplest to the most difficult) to lead variously abled pupils to examination success.

Evaluation of BICRON NE MCP DXT-RAD passive extremity dosemeter

CERN Document Server

Yuen, P S; Frketich, G; Rotunda, J

1999-01-01

Passive extremity dosemeters currently used in dosimetry communities worldwide have shortcomings. In general, an extremity dosemeter has too thick a detector element, and the dosemeter response is highly energy dependent for beta rays with energies ranging from 200 keV to 2 MeV. It often does not have dosemeter identification, causing problems in the chain of custody. It is often read manually, rendering reading/packing operations very labour intensive. As a result of collaboration between AECL and BICRON NE, a new extremity dosemeter, incorporating a highly sensitive LiF:Mg,Cu,P TLD and tentatively code named MCP DXT-RAD, was developed. It has been evaluated for radiological performance against an ISO draft standard for extremity dosemeters in twelve categories: homogeneity, detection threshold, beta ray energy response, beta angular response, photon energy response, photon angular response, reproducibility, stability under various climatic conditions, linearity, residue, self irradiation, and effect of ligh...

Predicting Growth Curves of Early Childhood Externalizing Problems: Differential Susceptibility of Children with Difficult Temperament

Science.gov (United States)

Mesman, Judi; Stoel, Reinoud; Bakermans-Kranenburg, Marian J.; van IJzendoorn, Marinus H.; Juffer, Femmie; Koot, Hans M.; Alink, Lenneke R. A.

2009-01-01

Using an accelerated longitudinal design, the development of externalizing problems from age 2 to 5 years was investigated in relation to maternal psychopathology, maternal parenting, gender, child temperament, and the presence of siblings. The sample consisted of 150 children selected at age 2-3 years for having high levels of externalizing…

Do changes in the frequency, magnitude and timing of extreme climatic events threaten the population viability of coastal birds?

NARCIS (Netherlands)

van de Pol, Martijn; Ens, Bruno J.; Heg, Dik; Brouwer, Lyanne; Krol, Johan; Maier, Martin; Exo, Klaus-Michael; Oosterbeek, Kees; Lok, Tamar; Eising, Corine M.; Koffijberg, Kees

P>1. Climate change encompasses changes in both the means and the extremes of climatic variables, but the population consequences of the latter are intrinsically difficult to study. 2. We investigated whether the frequency, magnitude and timing of rare but catastrophic flooding events have changed

Model of geophysical fields representation in problems of complex correlation-extreme navigation

Directory of Open Access Journals (Sweden)

Volodymyr KHARCHENKO

2015-09-01

Full Text Available A model of the optimal representation of spatial data for the task of complex correlation-extreme navigation is developed based on the criterion of minimum deviation of the correlation functions of the original and the resulting fields. Calculations are presented for one-dimensional case using the approximation of the correlation function by Fourier series. It is shown that in the presence of different geophysical map data fields their representation is possible by single template with optimal sampling without distorting the form of the correlation functions.

Non-linear time series extreme events and integer value problems

CERN Document Server

Turkman, Kamil Feridun; Zea Bermudez, Patrícia

2014-01-01

This book offers a useful combination of probabilistic and statistical tools for analyzing nonlinear time series. Key features of the book include a study of the extremal behavior of nonlinear time series and a comprehensive list of nonlinear models that address different aspects of nonlinearity. Several inferential methods, including quasi likelihood methods, sequential Markov Chain Monte Carlo Methods and particle filters, are also included so as to provide an overall view of the available tools for parameter estimation for nonlinear models. A chapter on integer time series models based on several thinning operations, which brings together all recent advances made in this area, is also included. Readers should have attended a prior course on linear time series, and a good grasp of simulation-based inferential methods is recommended. This book offers a valuable resource for second-year graduate students and researchers in statistics and other scientific areas who need a basic understanding of nonlinear time ...

Structural Identification Problem

Directory of Open Access Journals (Sweden)

Suvorov Aleksei

2016-01-01

Full Text Available The identification problem of the existing structures though the Quasi-Newton and its modification, Trust region algorithms is discussed. For the structural problems, which could be represented by means of the mathematical modelling of the finite element code discussed method is extremely useful. The nonlinear minimization problem of the L2 norm for the structures with linear elastic behaviour is solved by using of the Optimization Toolbox of Matlab. The direct and inverse procedures for the composition of the desired function to minimize are illustrated for the spatial 3D truss structure as well as for the problem of plane finite elements. The truss identification problem is solved with 2 and 3 unknown parameters in order to compare the computational efforts and for the graphical purposes. The particular commands of the Matlab codes are present in this paper.

[Ethical problems in organ transplantation].

Science.gov (United States)

Valenta, J; Treska, V; Hasman, D

1999-02-01

Organ transplantation is an accepted therapeutic method with good results, but it is connected with many not only medical but also ethical problems. One of the most important problems is the donor programme. In cadaverous donors the main ethical and legal question is the decision who can issue the consent with organ retrieval; in living donors it is the problem of motivation and financial compensation. Allocation of organs with low compatibility or from non-ideal donors, and the recipient's consent in these cases may involve difficult decisions.

Infrared spectrum of an extremely cool white-dwarf star

Science.gov (United States)

Hodgkin; Oppenheimer; Hambly; Jameson; Smartt; Steele

2000-01-06

White dwarfs are the remnant cores of stars that initially had masses of less than 8 solar masses. They cool gradually over billions of years, and have been suggested to make up much of the 'dark matter' in the halo of the Milky Way. But extremely cool white dwarfs have proved difficult to detect, owing to both their faintness and their anticipated similarity in colour to other classes of dwarf stars. Recent improved models indicate that white dwarfs are much more blue than previously supposed, suggesting that the earlier searches may have been looking for the wrong kinds of objects. Here we report an infrared spectrum of an extremely cool white dwarf that is consistent with the new models. We determine the star's temperature to be 3,500 +/- 200 K, making it the coolest known white dwarf. The kinematics of this star indicate that it is in the halo of the Milky Way, and the density of such objects implied by the serendipitous discovery of this star is consistent with white dwarfs dominating the dark matter in the halo.

A novel cannulation technique for difficult urethral catheterization

Directory of Open Access Journals (Sweden)

Mehmet Kaynar

2016-03-01

Full Text Available Introduction: To propose a novel cannulation technique for difficult urethral catheterization procedures. Technique: The sheath tip of an intravenous catheter is cut off, replaced to the needle tip and pushed through the distal drainage side hole to Foley catheter tip, and finally withdrawn for cannulation. In situations making urethral catheterization difficult, a guide wire is placed under direct vision. The modified Foley catheter is slid successfully over the guide wire from its distal end throughout the urethral passage into the bladder. Results: The modified Foley catheter was used successfully in our clinic in cases requiring difficult urethral catheterization. Conclusions: This easy and rapid modification of a Foley catheter may minimize the potential complications of blind catheter placement in standard catheterization.

Environmental policy-making in a difficult context: motorized two-wheeled vehicle emissions in India

International Nuclear Information System (INIS)

Badami, Madhav G.

2004-01-01

Motor vehicle activity is growing rapidly in India and other less-industrialized countries in Asia. This growth is contributing to serious health and welfare effects due to vehicle emissions, and energy insecurity, acidification and climate change. This paper applies the problem-structuring tools of 'value-focused thinking' to inform policy-making and implementation related to this complex problem in a difficult context, with specific reference to motorized two-wheeled vehicles, which play an important role in transport air pollution but also provide affordable mobility to millions with few other attractive options. The paper describes the process used to elicit and structure objectives and measures, based on interviews conducted by the author, and demonstrates how the objectives and measures can be used to more effectively characterize policy impacts, and create policy packages that have a better chance of long-term success

Dealing with difficult pasts

DEFF Research Database (Denmark)

McAtackney, Laura

2013-01-01

develop. I argue that such politically loaded manifestations of difficult pasts are highly significant during post-conflict renegotiations of society. They act as reminders of what happened, a commentary on how far society has – or has not moved on – and the potential for future relations and directions....... Using Robben Island and Long Kesh / Maze as case-studies this paper will explore the physical manifestations of political imprisonment, their experiences in the post-conflict context and reveal contestations of meaning at these dark heritage sites....

Automatic mesh adaptivity for CADIS and FW-CADIS neutronics modeling of difficult shielding problems

International Nuclear Information System (INIS)

Ibrahim, A. M.; Peplow, D. E.; Mosher, S. W.; Wagner, J. C.; Evans, T. M.; Wilson, P. P.; Sawan, M. E.

2013-01-01

The CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques dramatically increase the efficiency of neutronics modeling, but their use in the accurate design analysis of very large and geometrically complex nuclear systems has been limited by the large number of processors and memory requirements for their preliminary deterministic calculations and final Monte Carlo calculation. Three mesh adaptivity algorithms were developed to reduce the memory requirements of CADIS and FW-CADIS without sacrificing their efficiency improvement. First, a macro-material approach enhances the fidelity of the deterministic models without changing the mesh. Second, a deterministic mesh refinement algorithm generates meshes that capture as much geometric detail as possible without exceeding a specified maximum number of mesh elements. Finally, a weight window coarsening algorithm de-couples the weight window mesh and energy bins from the mesh and energy group structure of the deterministic calculations in order to remove the memory constraint of the weight window map from the deterministic mesh resolution. The three algorithms were used to enhance an FW-CADIS calculation of the prompt dose rate throughout the ITER experimental facility. Using these algorithms resulted in a 23.3% increase in the number of mesh tally elements in which the dose rates were calculated in a 10-day Monte Carlo calculation and, additionally, increased the efficiency of the Monte Carlo simulation by a factor of at least 3.4. The three algorithms enabled this difficult calculation to be accurately solved using an FW-CADIS simulation on a regular computer cluster, obviating the need for a world-class super computer. (authors)

Automatic mesh adaptivity for hybrid Monte Carlo/deterministic neutronics modeling of difficult shielding problems

International Nuclear Information System (INIS)

Ibrahim, Ahmad M.; Wilson, Paul P.H.; Sawan, Mohamed E.; Mosher, Scott W.; Peplow, Douglas E.; Wagner, John C.; Evans, Thomas M.; Grove, Robert E.

2015-01-01

The CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques dramatically increase the efficiency of neutronics modeling, but their use in the accurate design analysis of very large and geometrically complex nuclear systems has been limited by the large number of processors and memory requirements for their preliminary deterministic calculations and final Monte Carlo calculation. Three mesh adaptivity algorithms were developed to reduce the memory requirements of CADIS and FW-CADIS without sacrificing their efficiency improvement. First, a macromaterial approach enhances the fidelity of the deterministic models without changing the mesh. Second, a deterministic mesh refinement algorithm generates meshes that capture as much geometric detail as possible without exceeding a specified maximum number of mesh elements. Finally, a weight window coarsening algorithm decouples the weight window mesh and energy bins from the mesh and energy group structure of the deterministic calculations in order to remove the memory constraint of the weight window map from the deterministic mesh resolution. The three algorithms were used to enhance an FW-CADIS calculation of the prompt dose rate throughout the ITER experimental facility. Using these algorithms resulted in a 23.3% increase in the number of mesh tally elements in which the dose rates were calculated in a 10-day Monte Carlo calculation and, additionally, increased the efficiency of the Monte Carlo simulation by a factor of at least 3.4. The three algorithms enabled this difficult calculation to be accurately solved using an FW-CADIS simulation on a regular computer cluster, eliminating the need for a world-class super computer

Extremal black holes in dynamical Chern–Simons gravity

International Nuclear Information System (INIS)

McNees, Robert; Stein, Leo C; Yunes, Nicolás

2016-01-01

Rapidly rotating black hole (BH) solutions in theories beyond general relativity (GR) play a key role in experimental gravity, as they allow us to compute observables in extreme spacetimes that deviate from the predictions of GR. Such solutions are often difficult to find in beyond-general-relativity theories due to the inclusion of additional fields that couple to the metric nonlinearly and non-minimally. In this paper, we consider rotating BH solutions in one such theory, dynamical Chern–Simons (dCS) gravity, where the Einstein–Hilbert action is modified by the introduction of a dynamical scalar field that couples to the metric through the Pontryagin density. We treat dCS gravity as an effective field theory and work in the decoupling limit, where corrections are treated as small perturbations from GR. We perturb about the maximally rotating Kerr solution, the so-called extremal limit, and develop mathematical insight into the analysis techniques needed to construct solutions for generic spin. First we find closed-form, analytic expressions for the extremal scalar field, and then determine the trace of the metric perturbation, giving both in terms of Legendre decompositions. Retaining only the first three and four modes in the Legendre representation of the scalar field and the trace, respectively, suffices to ensure a fidelity of over 99% relative to full numerical solutions. The leading-order mode in the Legendre expansion of the trace of the metric perturbation contains a logarithmic divergence at the extremal Kerr horizon, which is likely to be unimportant as it occurs inside the perturbed dCS horizon. The techniques employed here should enable the construction of analytic, closed-form expressions for the scalar field and metric perturbations on a background with arbitrary rotation. (paper)

Diagnosis, treatment, and rehabilitation of stress fractures in the lower extremity in runners

Science.gov (United States)

Kahanov, Leamor; Eberman, Lindsey E; Games, Kenneth E; Wasik, Mitch

2015-01-01

Stress fractures account for between 1% and 20% of athletic injuries, with 80% of stress fractures in the lower extremity. Stress fractures of the lower extremity are common injuries among individuals who participate in endurance, high load-bearing activities such as running, military and aerobic exercise and therefore require practitioner expertise in diagnosis and management. Accurate diagnosis for stress fractures is dependent on the anatomical area. Anatomical regions such as the pelvis, sacrum, and metatarsals offer challenges due to difficulty differentiating pathologies with common symptoms. Special tests and treatment regimes, however, are similar among most stress fractures with resolution between 4 weeks to a year. The most difficult aspect of stress fracture treatment entails mitigating internal and external risk factors. Practitioners should address ongoing risk factors to minimize recurrence. PMID:25848327

[Difficult Ventilation Requiring Emergency Endotracheal Intubation during Awake Craniotomy Managed by Laryngeal Mask Airway].

Science.gov (United States)

Matsuda, Asako; Mizota, Toshiyuki; Tanaka, Tomoharu; Segawa, Hajime; Fukuda, Kazuhiko

2016-04-01

We report a case of difficult ventilation requiring emergency endotracheal intubation during awake craniotomy managed by laryngeal mask airway (LMA). A 45-year-old woman was scheduled to receive awake craniotomy for brain tumor in the frontal lobe. After anesthetic induction, airway was secured using ProSeal LMA and patient was mechanically ventilated in pressure-control mode. Patient's head was fixed with head-pins at anteflex position, and the operation started. About one hour after the start of the operation, tidal volume suddenly decreased. We immediately started manual ventilation, but the airway resistance was extremely high and we could not adequately ventilate the patient. We administered muscle relaxant for suspected laryngospasm, but ventilatory status did not improve; so we decided to conduct emergency endotracheal intubation. We tried to intubate using Airwayscope or LMA-Fastrach, but they were not effective in our case. Finally trachea was intubated using transnasal fiberoptic bronchoscopy. We discuss airway management during awake craniotomy, focusing on emergency endotracheal intubation during surgery.

Mandelbrot's Extremism

NARCIS (Netherlands)

Beirlant, J.; Schoutens, W.; Segers, J.J.J.

2004-01-01

In the sixties Mandelbrot already showed that extreme price swings are more likely than some of us think or incorporate in our models.A modern toolbox for analyzing such rare events can be found in the field of extreme value theory.At the core of extreme value theory lies the modelling of maxima

The Role of Expository Writing in Mathematical Problem Solving

Science.gov (United States)

Craig, Tracy S.

2016-01-01

Mathematical problem-solving is notoriously difficult to teach in a standard university mathematics classroom. The project on which this article reports aimed to investigate the effect of the writing of explanatory strategies in the context of mathematical problem solving on problem-solving behaviour. This article serves to describe the…

Stochastic Procedures for Extreme Wave Load Predictions- Wave Bending Moment in Ships

DEFF Research Database (Denmark)

Jensen, Jørgen Juncher

2009-01-01

A discussion of useful stochastic procedures for stochastic wave load problems is given, covering the range from slightly linear to strongly non-linear (bifurcation) problems. The methods are: Hermite transformation, Critical wave episodes and the First Order Reliability Method (FORM). The proced......). The procedures will be illustrated by results for the extreme vertical wave bending moment in ships....

Making Energy-Water Nexus Scenarios more Fit-for-Purpose through Better Characterization of Extremes

Science.gov (United States)

Yetman, G.; Levy, M. A.; Chen, R. S.; Schnarr, E.

2017-12-01

Often quantitative scenarios of future trends exhibit less variability than the historic data upon which the models that generate them are based. The problem of dampened variability, which typically also entails dampened extremes, manifests both temporally and spatially. As a result, risk assessments that rely on such scenarios are in danger of producing misleading results. This danger is pronounced in nexus issues, because of the multiple dimensions of change that are relevant. We illustrate the above problem by developing alternative joint distributions of the probability of drought and of human population totals, across U.S. counties over the period 2010-2030. For the dampened-extremes case we use drought frequencies derived from climate models used in the U.S. National Climate Assessment and the Environmental Protection Agency's population and land use projections contained in its Integrated Climate and Land Use Scenarios (ICLUS). For the elevated extremes case we use an alternative spatial drought frequency estimate based on tree-ring data, covering a 555-year period (Ho et al 2017); and we introduce greater temporal and spatial extremes in the ICLUS socioeconomic projections so that they conform to observed extremes in the historical U.S. spatial census data 1790-present (National Historical Geographic Information System). We use spatial and temporal coincidence of high population and extreme drought as a proxy for energy-water nexus risk. We compare the representation of risk in the dampened-extreme and elevated-extreme scenario analysis. We identify areas of the country where using more realistic portrayals of extremes makes the biggest difference in estimate risk and suggest implications for future risk assessments. References: Michelle Ho, Upmanu Lall, Xun Sun, Edward R. Cook. 2017. Multiscale temporal variability and regional patterns in 555 years of conterminous U.S. streamflow. Water Resources Research. . doi: 10.1002/2016WR019632

Adaptive Control Using Fully Online Sequential-Extreme Learning Machine and a Case Study on Engine Air-Fuel Ratio Regulation

Directory of Open Access Journals (Sweden)

Pak Kin Wong

2014-01-01

Full Text Available Most adaptive neural control schemes are based on stochastic gradient-descent backpropagation (SGBP, which suffers from local minima problem. Although the recently proposed regularized online sequential-extreme learning machine (ReOS-ELM can overcome this issue, it requires a batch of representative initial training data to construct a base model before online learning. The initial data is usually difficult to collect in adaptive control applications. Therefore, this paper proposes an improved version of ReOS-ELM, entitled fully online sequential-extreme learning machine (FOS-ELM. While retaining the advantages of ReOS-ELM, FOS-ELM discards the initial training phase, and hence becomes suitable for adaptive control applications. To demonstrate its effectiveness, FOS-ELM was applied to the adaptive control of engine air-fuel ratio based on a simulated engine model. Besides, controller parameters were also analyzed, in which it is found that large hidden node number with small regularization parameter leads to the best performance. A comparison among FOS-ELM and SGBP was also conducted. The result indicates that FOS-ELM achieves better tracking and convergence performance than SGBP, since FOS-ELM tends to learn the unknown engine model globally whereas SGBP tends to “forget” what it has learnt. This implies that FOS-ELM is more preferable for adaptive control applications.

Why Translation Is Difficult

DEFF Research Database (Denmark)

Carl, Michael; Schaeffer, Moritz Jonas

2017-01-01

The paper develops a definition of translation literality that is based on the syntactic and semantic similarity of the source and the target texts. We provide theoretical and empirical evidence that absolute literal translations are easy to produce. Based on a multilingual corpus of alternative...... translations we investigate the effects of cross-lingual syntactic and semantic distance on translation production times and find that non-literality makes from-scratch translation and post-editing difficult. We show that statistical machine translation systems encounter even more difficulties with non-literality....

ONE TYPICAL EXTREMUM IN ELECTRICAL PROBLEMS

Directory of Open Access Journals (Sweden)

V. I. Goroshko

2014-01-01

contrastive analysis of equations for calculation of extreme parameters in different electrical problems were used in this article. And as a result, it was determined that there is the same T-structure in equations, and this allow to develop the single approach for extreme parameters determination. It was shown that looking of extreme parameters in many electrical problems leads to analysis of the single mathematical T-structure. On the basis of T-structure analysis was obtained the single algorithm of extremum seeking. These five examples from different fields of electrical engineering present, first, typicalness of T-structure, the second, the simplicity obtaining of extreme parameters on the base of algorithm.

Extreme Politics: on Some Approaches to the Definition of the Category and Boundaries of the Phenomenon

Directory of Open Access Journals (Sweden)

Михаил Григорьевич Анохин

2010-06-01

Full Text Available The article is dedicated to the actual and underdeveloped problem of defining «extreme politics». The authors suppose that «extreme politics» is a special kind of human activities. Extreme politics is defined by the authors as an activity conducted for power in extreme conditions (situations tied with insufficiency of different resources, lack of time for analysis and long-term prognosis of political situation and political decision-making, deficit of actual information and its free circulation, dominance of authoritative leaders-competitors.

Therapist reactions in self-experienced difficult situations: an exploration

NARCIS (Netherlands)

Smith, A.J.M.; Kleijn, W.C.; Hutschemaekers, G.J.M.

2007-01-01

This article describes a qualitative study of 63 difficult therapeutic situations described by 26 therapists. The study was part of research on specific reactions of therapists to traumatized clients. The research questions for the current analyses focused on the categorization of difficult

Fiberoptic intubation through laryngeal mask airway for management of difficult airway in a child with Klippel-Feil syndrome

Directory of Open Access Journals (Sweden)

Ravi Bhat

2014-01-01

Full Text Available The ideal airway management modality in pediatric patients with syndromes like Klippel-Feil syndrome is a great challenge and is technically difficult for an anesthesiologist. Half of the patients present with the classic triad of short neck, low hairline, and fusion of cervical vertebra. Numerous associated anomalies like scoliosis or kyphosis, cleft palate, respiratory problems, deafness, genitourinary abnormalities, Sprengel′s deformity (wherein the scapulae ride high on the back, synkinesia, cervical ribs, and congenital heart diseases may further add to the difficulty. Fiberoptic bronchoscopy alone can be technically difficult and patient cooperation also becomes very important, which is difficult in pediatric patients. Fiberoptic bronchoscopy with the aid of supraglottic airway devices is a viable alternative in the management of difficult airway in children. We report a case of Klippel-Feil syndrome in an 18-month-old girl posted for cleft palate surgery. Imaging of spine revealed complete fusion of the cervical vertebrae with hypoplastic C3 and C6 vertebrae and thoracic kyphosis. We successfully managed airway in this patient by fiberoptic intubation through classic laryngeal mask airway (LMA. After intubation, we used second smaller endotracheal tube (ETT to stabilize and elongate the first ETT while removing the LMA.

How extreme is extreme hourly precipitation?

Science.gov (United States)

Papalexiou, Simon Michael; Dialynas, Yannis G.; Pappas, Christoforos

2016-04-01

The importance of accurate representation of precipitation at fine time scales (e.g., hourly), directly associated with flash flood events, is crucial in hydrological design and prediction. The upper part of a probability distribution, known as the distribution tail, determines the behavior of extreme events. In general, and loosely speaking, tails can be categorized in two families: the subexponential and the hyperexponential family, with the first generating more intense and more frequent extremes compared to the latter. In past studies, the focus has been mainly on daily precipitation, with the Gamma distribution being the most popular model. Here, we investigate the behaviour of tails of hourly precipitation by comparing the upper part of empirical distributions of thousands of records with three general types of tails corresponding to the Pareto, Lognormal, and Weibull distributions. Specifically, we use thousands of hourly rainfall records from all over the USA. The analysis indicates that heavier-tailed distributions describe better the observed hourly rainfall extremes in comparison to lighter tails. Traditional representations of the marginal distribution of hourly rainfall may significantly deviate from observed behaviours of extremes, with direct implications on hydroclimatic variables modelling and engineering design.

Problem solving and Program design using the TI-92

NARCIS (Netherlands)

Ir.ing. Ton Marée; ir Martijn van Dongen

2000-01-01

This textbook is intended for a basic course in problem solving and program design needed by scientists and engineers using the TI-92. The TI-92 is an extremely powerful problem solving tool that can help you manage complicated problems quickly. We assume no prior knowledge of computers or

Classification of Near-Horizon Geometries of Extremal Black Holes

Directory of Open Access Journals (Sweden)

Hari K. Kunduri

2013-09-01

Full Text Available Any spacetime containing a degenerate Killing horizon, such as an extremal black hole, possesses a well-defined notion of a near-horizon geometry. We review such near-horizon geometry solutions in a variety of dimensions and theories in a unified manner. We discuss various general results including horizon topology and near-horizon symmetry enhancement. We also discuss the status of the classification of near-horizon geometries in theories ranging from vacuum gravity to Einstein–Maxwell theory and supergravity theories. Finally, we discuss applications to the classification of extremal black holes and various related topics. Several new results are presented and open problems are highlighted throughout.

Classification of Near-Horizon Geometries of Extremal Black Holes.

Science.gov (United States)

Kunduri, Hari K; Lucietti, James

2013-01-01

Any spacetime containing a degenerate Killing horizon, such as an extremal black hole, possesses a well-defined notion of a near-horizon geometry. We review such near-horizon geometry solutions in a variety of dimensions and theories in a unified manner. We discuss various general results including horizon topology and near-horizon symmetry enhancement. We also discuss the status of the classification of near-horizon geometries in theories ranging from vacuum gravity to Einstein-Maxwell theory and supergravity theories. Finally, we discuss applications to the classification of extremal black holes and various related topics. Several new results are presented and open problems are highlighted throughout.

Extreme weather and climate events with ecological relevance: a review.

Science.gov (United States)

Ummenhofer, Caroline C; Meehl, Gerald A

2017-06-19

Robust evidence exists that certain extreme weather and climate events, especially daily temperature and precipitation extremes, have changed in regard to intensity and frequency over recent decades. These changes have been linked to human-induced climate change, while the degree to which climate change impacts an individual extreme climate event (ECE) is more difficult to quantify. Rapid progress in event attribution has recently been made through improved understanding of observed and simulated climate variability, methods for event attribution and advances in numerical modelling. Attribution for extreme temperature events is stronger compared with other event types, notably those related to the hydrological cycle. Recent advances in the understanding of ECEs, both in observations and their representation in state-of-the-art climate models, open new opportunities for assessing their effect on human and natural systems. Improved spatial resolution in global climate models and advances in statistical and dynamical downscaling now provide climatic information at appropriate spatial and temporal scales. Together with the continued development of Earth System Models that simulate biogeochemical cycles and interactions with the biosphere at increasing complexity, these make it possible to develop a mechanistic understanding of how ECEs affect biological processes, ecosystem functioning and adaptation capabilities. Limitations in the observational network, both for physical climate system parameters and even more so for long-term ecological monitoring, have hampered progress in understanding bio-physical interactions across a range of scales. New opportunities for assessing how ECEs modulate ecosystem structure and functioning arise from better scientific understanding of ECEs coupled with technological advances in observing systems and instrumentation.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events

Problems in diagnosing and forecasting power equipment reliability

Energy Technology Data Exchange (ETDEWEB)

Popkov, V I; Demirchyan, K S

1979-11-01

This general survey deals with approaches to the resolution of such problems as the gathering, analysis and systematization of data on component defects in power equipment and setting up feedback with the manufacturing plants and planning organizations to improve equipment reliability. Such efforts on the part of designers, manufacturers and operating and repair organizations in analyzing faults in 300 MW turbogenerators during 1974-1977 reduced the specific fault rate by 20 to 25% and the downtime per failure by 35 to 40%. Since power equipment should operate for several hundreds of thousands of hours (20 to 30 years) and the majority of power components have guaranteed service lives of no more than 10/sup 5/ hours, an extremely difficult problem is the determination of the reliability of equipment past the 10/sup 5/ point. The present trend in the USSR Unified Power System towards increasing the number of shutdowns and startups, which in the case of turbogenerators of up 1200 MW power can reach 7500 to 10,000 cycles is noted. Other areas briefly treated are: MHD generator reliability and economy; nuclear power plant reliability and safety; the reliability of high-power high-voltage thyristor converters; the difficulties involved in scale modeling of power system reliability and the high cost of the requisite full-scale studies; the poor understanding of long term corrosion and erosion processes. The review concludes with arguments in favor of greater computerization of all aspects of power system management.

What is the right way to talk about extreme events?

Science.gov (United States)

Sobel, A. H.

2013-12-01

Extreme weather events draw the attention of the public. By demonstrating the vulnerability of human society to climate, extreme events can cause nonscientists -government leaders as well as the broader population - to take the danger posed by anthropogenic global warming more seriously than they otherwise might. An extreme event that draws media attention can become a 'teachable moment'. But extreme events are difficult to talk about in a way that honors both the strengths and weaknesses of the underlying science. No single event can be attributed to climate change, and some types of events are not even clearly influenced by it (or not in any ways our science can yet demonstrate). Strong, media-friendly statements that closely connect specific events to climate - designed to make best use of the moment's teachability - can easily overstate the case. This will raise the hackles of one's colleagues, at a minimum, and at worst, may damage the credibility of the field more broadly. Yet talking too much about the uncertainties runs the risk of understating the basic truth that global warming is real and dangerous, and may lend inadvertent support to anti-scientific denialism. I will discuss this tension in the context of my own experiences in the media after 'Superstorm' Sandy. I will address arguments I have heard, from social scientists and media consultants, to the effect that climate scientists should adopt communications strategies that lead to stronger, more media-friendly statements, and learn to suppress the tendency, bred into us during our scientific training, to emphasize the uncertainties.

Clinical application of lower extremity CTA and lower extremity perfusion CT as a method of diagnostic for lower extremity atherosclerotic obliterans

Energy Technology Data Exchange (ETDEWEB)

Moon, Il Bong; Dong, Kyung Rae [Dept. Radiological Technology, Gwangju Health University, Gwangju (Korea, Republic of); Goo, Eun Hoe [Dept. Radiological Science, Cheongju University, Cheongju (Korea, Republic of)

2016-11-15

The purpose of this study was to assess clinical application of lower extremity CTA and lower extremity perfusion CT as a method of diagnostic for lower extremity atherosclerotic obliterans. From January to July 2016, 30 patients (mean age, 68) were studied with lower extremity CTA and lower extremity perfusion CT. 128 channel multi-detector row CT scans were acquired with a CT scanner (SOMATOM Definition Flash, Siemens medical solution, Germany) of lower extremity perfusion CT and lower extremity CTA. Acquired images were reconstructed with 3D workstation (Leonardo, Siemens, Germany). Site of lower extremity arterial occlusive and stenosis lesions were detected superficial femoral artery 36.6%, popliteal artery 23.4%, external iliac artery 16.7%, common femoral artery 13.3%, peroneal artery 10%. The mean total DLP comparison of lower extremity perfusion CT and lower extremity CTA, 650 mGy-cm and 675 mGy-cm, respectively. Lower extremity perfusion CT and lower extremity CTA were realized that were never be two examination that were exactly the same legions. Future through the development of lower extremity perfusion CT soft ware programs suggest possible clinical applications.

Thermodynamics of extremal rotating thin shells in an extremal BTZ spacetime and the extremal black hole entropy

Science.gov (United States)

Lemos, José P. S.; Minamitsuji, Masato; Zaslavskii, Oleg B.

2017-02-01

In a (2 +1 )-dimensional spacetime with a negative cosmological constant, the thermodynamics and the entropy of an extremal rotating thin shell, i.e., an extremal rotating ring, are investigated. The outer and inner regions with respect to the shell are taken to be the Bañados-Teitelbom-Zanelli (BTZ) spacetime and the vacuum ground state anti-de Sitter spacetime, respectively. By applying the first law of thermodynamics to the extremal thin shell, one shows that the entropy of the shell is an arbitrary well-behaved function of the gravitational area A+ alone, S =S (A+). When the thin shell approaches its own gravitational radius r+ and turns into an extremal rotating BTZ black hole, it is found that the entropy of the spacetime remains such a function of A+, both when the local temperature of the shell at the gravitational radius is zero and nonzero. It is thus vindicated by this analysis that extremal black holes, here extremal BTZ black holes, have different properties from the corresponding nonextremal black holes, which have a definite entropy, the Bekenstein-Hawking entropy S (A+)=A/+4G , where G is the gravitational constant. It is argued that for extremal black holes, in particular for extremal BTZ black holes, one should set 0 ≤S (A+)≤A/+4G;i.e., the extremal black hole entropy has values in between zero and the maximum Bekenstein-Hawking entropy A/+4 G . Thus, rather than having just two entropies for extremal black holes, as previous results have debated, namely, 0 and A/+4 G , it is shown here that extremal black holes, in particular extremal BTZ black holes, may have a continuous range of entropies, limited by precisely those two entropies. Surely, the entropy that a particular extremal black hole picks must depend on past processes, notably on how it was formed. A remarkable relation between the third law of thermodynamics and the impossibility for a massive body to reach the velocity of light is also found. In addition, in the procedure, it

Web Based Information System for Job Training Activities Using Personal Extreme Programming (PXP)

Science.gov (United States)

Asri, S. A.; Sunaya, I. G. A. M.; Rudiastari, E.; Setiawan, W.

2018-01-01

Job training is one of the subjects in university or polytechnic that involves many users and reporting activities. Time and distance became problems for users to reporting and to do obligations tasks during job training due to the location where the job training took place. This research tried to develop a web based information system of job training to overcome the problems. This system was developed using Personal Extreme Programming (PXP). PXP is one of the agile methods is combination of Extreme Programming (XP) and Personal Software Process (PSP). The information system that has developed and tested which are 24% of users are strongly agree, 74% are agree, 1% disagree and 0% strongly disagree about system functionality.

Moral responsibility and the problem of many hands

NARCIS (Netherlands)

Poel, van de I.R.; Royakkers, L.M.M.; Zwart, S.D.

2015-01-01

When many people are involved in an activity, it is often difficult, if not impossible, to pinpoint who is morally responsible for what, a phenomenon known as the 'problem of many hands.' This term is increasingly used to describe problems with attributing individual responsibility in collective

CHRISTMAS 2014 : GOING TO EXTREMES Nintendo related injuries and other problems: review

NARCIS (Netherlands)

Jalink, Maarten B.; Heineman, Erik; Pierie, Jean-Pierre E. N.; Hoedemaker, Henk O. ten Cate

2014-01-01

Objective To identify all reported cases of injury and other problems caused by using a Nintendo video gaming system. Design Review. Data sources and review methods Search of PubMed and Embase in June 2014 for reports on injuries and other problems caused by using a Nintendo gaming system. Results

Symmetry-adapted basis sets automatic generation for problems in chemistry and physics

CERN Document Server

Avery, John Scales; Avery, James Emil

2012-01-01

In theoretical physics, theoretical chemistry and engineering, one often wishes to solve partial differential equations subject to a set of boundary conditions. This gives rise to eigenvalue problems of which some solutions may be very difficult to find. For example, the problem of finding eigenfunctions and eigenvalues for the Hamiltonian of a many-particle system is usually so difficult that it requires approximate methods, the most common of which is expansion of the eigenfunctions in terms of basis functions that obey the boundary conditions of the problem. The computational effort needed

One-dimensional Gromov minimal filling problem

International Nuclear Information System (INIS)

Ivanov, Alexandr O; Tuzhilin, Alexey A

2012-01-01

The paper is devoted to a new branch in the theory of one-dimensional variational problems with branching extremals, the investigation of one-dimensional minimal fillings introduced by the authors. On the one hand, this problem is a one-dimensional version of a generalization of Gromov's minimal fillings problem to the case of stratified manifolds. On the other hand, this problem is interesting in itself and also can be considered as a generalization of another classical problem, the Steiner problem on the construction of a shortest network connecting a given set of terminals. Besides the statement of the problem, we discuss several properties of the minimal fillings and state several conjectures. Bibliography: 38 titles.

Extreme value distributions

CERN Document Server

Ahsanullah, Mohammad

2016-01-01

The aim of the book is to give a through account of the basic theory of extreme value distributions. The book cover a wide range of materials available to date. The central ideas and results of extreme value distributions are presented. The book rwill be useful o applied statisticians as well statisticians interrested to work in the area of extreme value distributions.vmonograph presents the central ideas and results of extreme value distributions.The monograph gives self-contained of theory and applications of extreme value distributions.

Lingual traction to facilitate fiber-optic intubation of difficult airways: a single-anesthesiologist randomized trial.

Science.gov (United States)

Ching, Yiu-Hei; Karlnoski, Rachel A; Chen, Henian; Camporesi, Enrico M; Shah, Vimal V; Padhya, Tapan A; Mangar, Devanand

2015-04-01

Flexible fiber-optic bronchoscope-guided orotracheal intubation is a valuable technique with demonstrated benefits in the management of difficult airways. Despite its popularity with anesthesia providers, the technique is not fail-safe and airway-related complications secondary to failed intubation attempts remain an important problem. We sought to determine the effect of incorporating lingual traction on the success rate of fiber-optic bronchoscope-guided intubation in patients with anticipated difficult airways. In this prospective, randomized, cohort study, we enrolled 91 adult patients with anticipated difficult airways scheduled for elective surgery to undergo fiber-optic bronchoscope-guided orotracheal intubation alone or with lingual traction by an individual anesthesiologist after induction of general anesthesia and neuromuscular blockade. A total of 78 patients were randomized: 39 patients to the fiber-optic bronchoscope-guided intubation with lingual traction group and 39 patients to the fiber-optic bronchoscope-guided intubation alone group. The primary endpoint was the rate of successful first attempt intubations. The secondary outcome was sore throat grade on post-operative day 1. Fiber-optic intubation with lingual traction compared to fiber-optic intubation alone resulted in a higher success rate (92.3 vs. 74.4 %, χ (2) = 4.523, p = 0.033) and greater odds for successful first attempt intubation (OR 4.138, 95 % CI 1.041-16.444, p = 0.044). Sore throat severity on post-operative day 1 was not significantly different but trended towards worsening grades with lingual traction. In this study, lingual traction was shown to be a valuable maneuver for facilitating fiber-optic bronchoscope-guided intubation in the management of patients with anticipated difficult airways.

Impact of extreme load requirements and quality assurance on nuclear power plant costs

International Nuclear Information System (INIS)

Stevenson, J.D.

1993-01-01

Definitive costs, applicable to nuclear power plant concrete structures, as a function of National Regulatory Requirements, standardization, the effect of extreme load design associated with both design basis accidents and extreme external events and quality assurance are difficult to develop since such effects are interrelated and not only differ widely from country to country, project to project but also vary in time. Table 1 shows an estimate of the of the overall plant cost effects of external event extreme load design on nuclear power plant design for the U.S -and selected foreign countries for which experience with LWRs exist- Germany is the most expensive primarily due to a military aircraft crash resistance. However, the German requirement for 4 safeguards trains rather than 2 and the containment design requirement to consider one Steam Generator blowdown concurrent with a RCS blowdown. This presentation will concentrate on the direct current impact extreme load design and quality assurance have on concrete structures, systems and components for nuclear plants. This presentation is considered timely due to the increased interest in the c potential backfit of Eastern European nuclear power stations of the WWER 440 and WWER 1000 types which typically did not consider the extreme loads identified in Table 1 and accident loads in Table 3 and quality assurance in Table 5 in their original design. Concrete structures in particular are highlighted because they typically form the last barrier to radioactive release from the containment and other Safety Related Structures

An Electrostatics Approach to the Determination of Extremal Measures

Energy Technology Data Exchange (ETDEWEB)

Meinguet, Jean [Universite Catholique de Louvain, Institut Mathematique, Chemin du Cyclotron 2 (Belgium)], E-mail: meinguet@anma.ucl.ac.be

2000-12-15

One of the most important aspects of the minimal energy (or induced equilibrium) problem in the presence of an external field - sometimes referred to as the Gauss variation problem - is the determination of the support of its solution (the so-called extremal measure associated with the field). A simple electrostatic interpretation is presented here, which is apparently new and anyway suggests a novel, rather systematic approach to the solution. By way of illustration, the classical results for Jacobi, Laguerre and Freud weights are explicitly recovered by this alternative method.

An Electrostatics Approach to the Determination of Extremal Measures

International Nuclear Information System (INIS)

Meinguet, Jean

2000-01-01

One of the most important aspects of the minimal energy (or induced equilibrium) problem in the presence of an external field - sometimes referred to as the Gauss variation problem - is the determination of the support of its solution (the so-called extremal measure associated with the field). A simple electrostatic interpretation is presented here, which is apparently new and anyway suggests a novel, rather systematic approach to the solution. By way of illustration, the classical results for Jacobi, Laguerre and Freud weights are explicitly recovered by this alternative method

Can Concentration - Discharge Relationships Diagnose Material Source During Extreme Events?

Science.gov (United States)

Karwan, D. L.; Godsey, S.; Rose, L.

2017-12-01

Floods can carry >90% of the basin material exported in a given year as well as alter flow pathways and material sources. In turn, sediment and solute fluxes can increase flood damages and negatively impact water quality and integrate physical and chemical weathering of landscapes and channels. Concentration-discharge (C-Q) relationships are used to both describe export patterns as well as compute them. Metrics for describing C-Q patterns and inferring their controls are vulnerable to infrequent sampling that affects how C-Q relationships are interpolated and interpreted. C-Q relationships are typically evaluated from multiple samples, but because hydrological extremes are rare, data are often unavailable for extreme events. Because solute and sediment C-Q relationships likely respond to changes in hydrologic extremes in different ways, there is a pressing need to define their behavior under extreme conditions, including how to properly sample to capture these patterns. In the absence of such knowledge, improving load estimates in extreme floods will likely remain difficult. Here we explore the use of C-Q relationships to determine when an event alters a watershed system such that it enters a new material source/transport regime. We focus on watersheds with sediment and discharge time series include low-frequency and/or extreme events. For example, we compare solute and sediment patterns in White Clay Creek in southeastern Pennsylvania across a range of flows inclusive of multiple hurricanes for which we have ample ancillary hydrochemical data. TSS is consistently mobilized during high flow events, even during extreme floods associated with hurricanes, and sediment fingerprinting indicates different sediment sources, including in-channel remobilization and landscape erosion, are active at different times. In other words, TSS mobilization in C-Q space is not sensitive to the source of material being mobilized. Unlike sediments, weathering solutes in this watershed

Exascale Co-design for Modeling Materials in Extreme Environments

Energy Technology Data Exchange (ETDEWEB)

Germann, Timothy C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-07-08

Computational materials science has provided great insight into the response of materials under extreme conditions that are difficult to probe experimentally. For example, shock-induced plasticity and phase transformation processes in single-crystal and nanocrystalline metals have been widely studied via large-scale molecular dynamics simulations, and many of these predictions are beginning to be tested at advanced 4th generation light sources such as the Advanced Photon Source (APS) and Linac Coherent Light Source (LCLS). I will describe our simulation predictions and their recent verification at LCLS, outstanding challenges in modeling the response of materials to extreme mechanical and radiation environments, and our efforts to tackle these as part of the multi-institutional, multi-disciplinary Exascale Co-design Center for Materials in Extreme Environments (ExMatEx). ExMatEx has initiated an early and deep collaboration between domain (computational materials) scientists, applied mathematicians, computer scientists, and hardware architects, in order to establish the relationships between algorithms, software stacks, and architectures needed to enable exascale-ready materials science application codes within the next decade. We anticipate that we will be able to exploit hierarchical, heterogeneous architectures to achieve more realistic large-scale simulations with adaptive physics refinement, and are using tractable application scale-bridging proxy application testbeds to assess new approaches and requirements. Such current scale-bridging strategies accumulate (or recompute) a distributed response database from fine-scale calculations, in a top-down rather than bottom-up multiscale approach.

Fast, Simple and Accurate Handwritten Digit Classification by Training Shallow Neural Network Classifiers with the 'Extreme Learning Machine' Algorithm.

Directory of Open Access Journals (Sweden)

Mark D McDonnell

Full Text Available Recent advances in training deep (multi-layer architectures have inspired a renaissance in neural network use. For example, deep convolutional networks are becoming the default option for difficult tasks on large datasets, such as image and speech recognition. However, here we show that error rates below 1% on the MNIST handwritten digit benchmark can be replicated with shallow non-convolutional neural networks. This is achieved by training such networks using the 'Extreme Learning Machine' (ELM approach, which also enables a very rapid training time (∼ 10 minutes. Adding distortions, as is common practise for MNIST, reduces error rates even further. Our methods are also shown to be capable of achieving less than 5.5% error rates on the NORB image database. To achieve these results, we introduce several enhancements to the standard ELM algorithm, which individually and in combination can significantly improve performance. The main innovation is to ensure each hidden-unit operates only on a randomly sized and positioned patch of each image. This form of random 'receptive field' sampling of the input ensures the input weight matrix is sparse, with about 90% of weights equal to zero. Furthermore, combining our methods with a small number of iterations of a single-batch backpropagation method can significantly reduce the number of hidden-units required to achieve a particular performance. Our close to state-of-the-art results for MNIST and NORB suggest that the ease of use and accuracy of the ELM algorithm for designing a single-hidden-layer neural network classifier should cause it to be given greater consideration either as a standalone method for simpler problems, or as the final classification stage in deep neural networks applied to more difficult problems.

Application of Extreme Learning Machines to inverse neutron kinetics

International Nuclear Information System (INIS)

Picca, Paolo; Furfaro, Roberto

2017-01-01

Highlights: • The paper applies the Extreme Learning Machines (ELMs) to inverse reactor problems. • Multi-group transport model is used for the inversion as opposed to point kinetics. • ELMs are compared against Artificial Neural Networks (ANNs). • Various options are tested to improve the reliability of the estimation. • Results highlight the potential of the ELM approach. - Abstract: The paper presents the application of Extreme Leaning Machines (ELMs) for inverse reactor kinetic applications. ELMs were proposed by Huang and co-workers (2004, 2006a,b, 2015), which showed their enhances capabilities in terms of training speed and generalization with respect to classical Artificial Neural Networks (ANNs). ELMs are here implemented for reactivity determination as an alternative to ANNs (e.g. Picca et al. (2008)) and Gaussian Processes (Picca and Furfaro, 2012). After a review of the main features of ELMs, their application to inverse kinetic problems is proposed. The ELMs performance is tested on a typical accelerator drive system configuration (Yalina reactor) and the inversion is carried out on an accurate kinetic model (multi-group transport).

An Extremal Eigenvalue Problem for a Two-Phase Conductor in a Ball

International Nuclear Information System (INIS)

Conca, Carlos; Mahadevan, Rajesh; Sanz, Leon

2009-01-01

The pioneering works of Murat and Tartar (Topics in the mathematical modeling of composite materials. PNLDE 31. Birkhaeuser, Basel, 1997) go a long way in showing, in general, that problems of optimal design may not admit solutions if microstructural designs are excluded from consideration. Therefore, assuming, tactilely, that the problem of minimizing the first eigenvalue of a two-phase conducting material with the conducting phases to be distributed in a fixed proportion in a given domain has no true solution in general domains, Cox and Lipton only study conditions for an optimal microstructural design (Cox and Lipton in Arch. Ration. Mech. Anal. 136:101-117, 1996). Although, the problem in one dimension has a solution (cf. Krein in AMS Transl. Ser. 2(1):163-187, 1955) and, in higher dimensions, the problem set in a ball can be deduced to have a radially symmetric solution (cf. Alvino et al. in Nonlinear Anal. TMA 13(2):185-220, 1989), these existence results have been regarded so far as being exceptional owing to complete symmetry. It is still not clear why the same problem in domains with partial symmetry should fail to have a solution which does not develop microstructure and respecting the symmetry of the domain. We hope to revive interest in this question by giving a new proof of the result in a ball using a simpler symmetrization result from Alvino and Trombetti (J. Math. Anal. Appl. 94:328-337, 1983)

Secondary stressors and extreme events and disasters: a systematic review of primary research from 2010-2011

Science.gov (United States)

Lock, Sarah; Rubin, G. James; Murray, Virginia; Rogers, M. Brooke; Amlôt, Richard; Williams, Richard

2012-01-01

Introduction Extreme events and disasters, such as earthquakes and floods, cause distress and are associated with some people developing mental disorders. Primary stressors inherent in many disasters can include injuries sustained or watching someone die. The literature recognises the distress which primary stressors cause and their association with mental disorders. Secondary stressors such as a lack of financial assistance, the gruelling process of submitting an insurance claim, parents’ worries about their children, and continued lack of infrastructure can manifest their effects shortly after a disaster and persist for extended periods of time. Secondary stressors, and their roles in affecting people’s longer-term mental health, should not be overlooked. We draw attention in this review to the nature of secondary stressors that are commonly identified in the literature, assess how they are measured, and develop a typology of these stressors that often affect people after extreme events. Methods We searched for relevant papers from 2010 and 2011 using MEDLINE®, Embase and PsycINFO®. We selected primary research papers that evaluated the associations between secondary stressors and distress or mental disorders following extreme events, and were published in English. We extracted information on which secondary stressors were assessed, and used thematic analysis to group the secondary stressors into a typology. Results Thirty-two relevant articles published in 2010 and 2011 were identified. Many secondary stressors were poorly defined and difficult to differentiate from primary stressors or other life events. We identified 11 categories of secondary stressors, though some extend over more than one category. The categories include: economic stressors such as problems with compensation, recovery of and rebuilding homes; loss of physical possessions and resources; health-related stressors; stress relating to education and schooling; stress arising from media

Multidisciplinary Difficult Airway Course: An Essential Educational Component of a Hospital-Wide Difficult Airway Response Program.

Science.gov (United States)

Leeper, W Robert; Haut, Elliott R; Pandian, Vinciya; Nakka, Sajan; Dodd-O, Jeffrey; Bhatti, Nasir; Hunt, Elizabeth A; Saheed, Mustapha; Dalesio, Nicholas; Schiavi, Adam; Miller, Christina; Kirsch, Thomas D; Berkow, Lauren

2018-04-05

A hospital-wide difficult airway response team was developed in 2008 at The Johns Hopkins Hospital with three central pillars: operations, safety monitoring, and education. The objective of this study was to assess the outcomes of the educational pillar of the difficult airway response team program, known as the multidisciplinary difficult airway course (MDAC). The comprehensive, full-day MDAC involves trainees and staff from all provider groups who participate in airway management. The MDAC occurs within the Johns Hopkins Medicine Simulation Center approximately four times per year and uses a combination of didactic lectures, hands-on sessions, and high-fidelity simulation training. Participation in MDAC is the main intervention being investigated in this study. Data were collected prospectively using course evaluation survey with quantitative and qualitative components, and prepost course knowledge assessment multiple choice questions (MCQ). Outcomes include course evaluation scores and themes derived from qualitative assessments, and prepost course knowledge assessment MCQ scores. Tertiary care academic hospital center PARTICIPANTS: Students, residents, fellows, and practicing physicians from the departments of Surgery, Otolaryngology Head and Neck Surgery, Anesthesiology/Critical Care Medicine, and Emergency Medicine; advanced practice providers (nurse practitioners and physician assistants), nurse anesthetists, nurses, and respiratory therapists. Totally, 23 MDACs have been conducted, including 499 participants. Course evaluations were uniformly positive with mean score of 86.9 of 95 points. Qualitative responses suggest major value from high-fidelity simulation, the hands-on skill stations, and teamwork practice. MCQ scores demonstrated significant improvement: median (interquartile range) pre: 69% (60%-81%) vs post: 81% (72%-89%), p < 0.001. Implementation of a MDAC successfully disseminated principles and protocols to all airway providers. Demonstrable

Neural architecture design based on extreme learning machine.

Science.gov (United States)

Bueno-Crespo, Andrés; García-Laencina, Pedro J; Sancho-Gómez, José-Luis

2013-12-01

Selection of the optimal neural architecture to solve a pattern classification problem entails to choose the relevant input units, the number of hidden neurons and its corresponding interconnection weights. This problem has been widely studied in many research works but their solutions usually involve excessive computational cost in most of the problems and they do not provide a unique solution. This paper proposes a new technique to efficiently design the MultiLayer Perceptron (MLP) architecture for classification using the Extreme Learning Machine (ELM) algorithm. The proposed method provides a high generalization capability and a unique solution for the architecture design. Moreover, the selected final network only retains those input connections that are relevant for the classification task. Experimental results show these advantages. Copyright © 2013 Elsevier Ltd. All rights reserved.

Overweight, Obesity, and Extreme Obesity Among Mississippi Adults, 2001?2010 and 2011?2015

OpenAIRE

Mendy, Vincent L.; Vargas, Rodolfo; Cannon-Smith, Gerri; Payton, Marinelle

2017-01-01

Introduction In 2015, about 1.5 million adults in Mississippi were overweight or obese. Obesity is associated with increased risk for diabetes and cardiovascular problems. We examined trends in the prevalence of overweight, obesity, and extreme obesity from 2001 through 2010 and 2011 through 2015. Methods We used data from the Mississippi Behavioral Risk Factor Surveillance System to analyze trends in the prevalence of overweight, obesity, and extreme obesity among adults from 2001 through 20...

Computational problems in engineering

CERN Document Server

Mladenov, Valeri

2014-01-01

This book provides readers with modern computational techniques for solving variety of problems from electrical, mechanical, civil and chemical engineering. Mathematical methods are presented in a unified manner, so they can be applied consistently to problems in applied electromagnetics, strength of materials, fluid mechanics, heat and mass transfer, environmental engineering, biomedical engineering, signal processing, automatic control and more.   • Features contributions from distinguished researchers on significant aspects of current numerical methods and computational mathematics; • Presents actual results and innovative methods that provide numerical solutions, while minimizing computing times; • Includes new and advanced methods and modern variations of known techniques that can solve difficult scientific problems efficiently.  

Disarming Contankerous People: Coping with Difficult Personalities in ECE Work Settings

Science.gov (United States)

Hernandez, Luis; Smith, Connie Jo

2009-01-01

Difficult personalities come in a variety of roles in just about every setting. While types have been identified in the typical corporate and business culture, difficult work personalities also inhabit the world of early childhood education (ECE) workplaces. Because difficult people have an impact on workplace morale and productivity, the topic…

The effectiveness of search dogs compared with humans in searching difficult terrain at turbine sites for bat fatalities

Energy Technology Data Exchange (ETDEWEB)

Mathews, Fiona

2011-07-01

Full text: Many wind farms in the UK and elsewhere in northern Europe are situated in habitat with dense tall vegetation such as arable fields and upland heaths. This makes surveying for bat fatalities extremely difficult. To facilitate a multi-centre study of the effects of wind turbines on British bats, we have therefore conducted controlled trials of the relative success of trained search dogs and ecologists in retrieving bat carcasses. Although dogs have been used previously in ecological surveys for bats, this is the first time they have been specifically trained for use in 'difficult to survey' habitats. Two ecologists and two Labrador dogs with handlers were each given the opportunity to retrieve up to 45 bat carcasses in a range of habitat types. Their efficiency in terms of overall search time, costs, and retrieval abilities were evaluated. Our results indicate that high rates of retrieval can be achieved by dogs, even in dense vegetation up to 75cm high. Further, a typical 100m2 search area can be surveyed in less than half the time taken by humans. The limitations of using search dogs, and their ability to detect the presence of bats that have been scavenged are also presented (presentation supported with video footage). (Author)

Extremely Preterm Birth

Science.gov (United States)

... Events Advocacy For Patients About ACOG Extremely Preterm Birth Home For Patients Search FAQs Extremely Preterm Birth ... Spanish FAQ173, June 2016 PDF Format Extremely Preterm Birth Pregnancy When is a baby considered “preterm” or “ ...

The three-body problem

CERN Document Server

Marchal, Christian

1990-01-01

Recent research on the theory of perturbations, the analytical approach and the quantitative analysis of the three-body problem have reached a high degree of perfection. The use of electronics has aided developments in quantitative analysis and has helped to disclose the extreme complexity of the set of solutions. This accelerated progress has given new orientation and impetus to the qualitative analysis that is so complementary to the quantitative analysis. The book begins with the various formulations of the three-body problem, the main classical results and the important questions and conje

Statistical physics of hard optimization problems

International Nuclear Information System (INIS)

Zdeborova, L.

2009-01-01

Optimization is fundamental in many areas of science, from computer science and information theory to engineering and statistical physics, as well as to biology or social sciences. It typically involves a large number of variables and a cost function depending on these variables. Optimization problems in the non-deterministic polynomial (NP)-complete class are particularly difficult, it is believed that the number of operations required to minimize the cost function is in the most difficult cases exponential in the system size. However, even in an NP-complete problem the practically arising instances might, in fact, be easy to solve. The principal question we address in this article is: How to recognize if an NP-complete constraint satisfaction problem is typically hard and what are the main reasons for this? We adopt approaches from the statistical physics of disordered systems, in particular the cavity method developed originally to describe glassy systems. We describe new properties of the space of solutions in two of the most studied constraint satisfaction problems - random satisfy ability and random graph coloring. We suggest a relation between the existence of the so-called frozen variables and the algorithmic hardness of a problem. Based on these insights, we introduce a new class of problems which we named ”locked” constraint satisfaction, where the statistical description is easily solvable, but from the algorithmic point of view they are even more challenging than the canonical satisfy ability.

Statistical physics of hard optimization problems

International Nuclear Information System (INIS)

Zdeborova, L.

2009-01-01

Optimization is fundamental in many areas of science, from computer science and information theory to engineering and statistical physics, as well as to biology or social sciences. It typically involves a large number of variables and a cost function depending on these variables. Optimization problems in the non-deterministic polynomial-complete class are particularly difficult, it is believed that the number of operations required to minimize the cost function is in the most difficult cases exponential in the system size. However, even in an non-deterministic polynomial-complete problem the practically arising instances might, in fact, be easy to solve. The principal the question we address in the article is: How to recognize if an non-deterministic polynomial-complete constraint satisfaction problem is typically hard and what are the main reasons for this? We adopt approaches from the statistical physics of disordered systems, in particular the cavity method developed originally to describe glassy systems. We describe new properties of the space of solutions in two of the most studied constraint satisfaction problems - random satisfiability and random graph coloring. We suggest a relation between the existence of the so-called frozen variables and the algorithmic hardness of a problem. Based on these insights, we introduce a new class of problems which we named 'locked' constraint satisfaction, where the statistical description is easily solvable, but from the algorithmic point of view they are even more challenging than the canonical satisfiability (Authors)

Statistical physics of hard optimization problems

Science.gov (United States)

Zdeborová, Lenka

2009-06-01

Optimization is fundamental in many areas of science, from computer science and information theory to engineering and statistical physics, as well as to biology or social sciences. It typically involves a large number of variables and a cost function depending on these variables. Optimization problems in the non-deterministic polynomial (NP)-complete class are particularly difficult, it is believed that the number of operations required to minimize the cost function is in the most difficult cases exponential in the system size. However, even in an NP-complete problem the practically arising instances might, in fact, be easy to solve. The principal question we address in this article is: How to recognize if an NP-complete constraint satisfaction problem is typically hard and what are the main reasons for this? We adopt approaches from the statistical physics of disordered systems, in particular the cavity method developed originally to describe glassy systems. We describe new properties of the space of solutions in two of the most studied constraint satisfaction problems - random satisfiability and random graph coloring. We suggest a relation between the existence of the so-called frozen variables and the algorithmic hardness of a problem. Based on these insights, we introduce a new class of problems which we named "locked" constraint satisfaction, where the statistical description is easily solvable, but from the algorithmic point of view they are even more challenging than the canonical satisfiability.

Extreme fluxes in solar energetic particle events: Methodological and physical limitations

International Nuclear Information System (INIS)

Miroshnichenko, L.I.; Nymmik, R.A.

2014-01-01

In this study, all available data on the largest solar proton events (SPEs), or extreme solar energetic particle (SEP) events, for the period from 1561 up to now are analyzed. Under consideration are the observational, methodological and physical problems of energy-spectrum presentation for SEP fluxes (fluences) near the Earth's orbit. Special attention is paid to the study of the distribution function for extreme fluences of SEPs by their sizes. The authors present advances in at least three aspects: 1) a form of the distribution function that was previously obtained from the data for three cycles of solar activity has been completely confirmed by the data for 41 solar cycles; 2) early estimates of extremely large fluences in the past have been critically revised, and their values were found to be overestimated; and 3) extremely large SEP fluxes are shown to obey a probabilistic distribution, so the concept of an “upper limit flux” does not carry any strict physical sense although it serves as an important empirical restriction. SEP fluxes may only be characterized by the relative probabilities of their appearance, and there is a sharp break in the spectrum in the range of large fluences (or low probabilities). It is emphasized that modern observational data and methods of investigation do not allow, for the present, the precise resolution of the problem of the spectrum break or the estimation of the maximum potentialities of solar accelerator(s). This limitation considerably restricts the extrapolation of the obtained results to the past and future for application to the epochs with different levels of solar activity. - Highlights: • All available data on the largest solar proton events (SPEs) are analyzed. • Distribution function obtained for 3 last cycles is confirmed for 41 solar cycles. • Estimates of extremely large fluences in the past are found to be overestimated. • Extremely large SEP fluxes are shown to obey a probabilistic distribution. �

An unusual cause of difficult weaning in a patient with newly diagnosed small cell lung cancer

Directory of Open Access Journals (Sweden)

G. Deslypere

2015-01-01

Full Text Available We describe a patient with acute respiratory insufficiency and difficult ventilator weaning in the ICU ward, leading to diagnosis of small cell lung cancer with superior vena cava superior syndrome. Bilateral vocal cord paralysis caused his respiratory distress and weaning difficulties. Thyroidectomy and neurological problems (such as Parkinson disease and Guillain Barré syndrome are more common causes of bilateral vocal cord paralysis. Lung cancer patients are also at risk due to mediastinal invasion. The left recurrent laryngeal nerve is more prone to paralysis because of the typical anatomy. In contrary, bilateral vocal cord paralysis is rare and doesn't result in speech problems but rather breathing difficulties. Tracheostomy is the classic therapy, but laser cordectomy and Botulinum toxin injection in the laryngeal muscles are alternatives.

Agent Based Simulation of Group Emotions Evolution and Strategy Intervention in Extreme Events

Directory of Open Access Journals (Sweden)

Bo Li

2014-01-01

Full Text Available Agent based simulation method has become a prominent approach in computational modeling and analysis of public emergency management in social science research. The group emotions evolution, information diffusion, and collective behavior selection make extreme incidents studies a complex system problem, which requires new methods for incidents management and strategy evaluation. This paper studies the group emotion evolution and intervention strategy effectiveness using agent based simulation method. By employing a computational experimentation methodology, we construct the group emotion evolution as a complex system and test the effects of three strategies. In addition, the events-chain model is proposed to model the accumulation influence of the temporal successive events. Each strategy is examined through three simulation experiments, including two make-up scenarios and a real case study. We show how various strategies could impact the group emotion evolution in terms of the complex emergence and emotion accumulation influence in extreme events. This paper also provides an effective method of how to use agent-based simulation for the study of complex collective behavior evolution problem in extreme incidents, emergency, and security study domains.

Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

Directory of Open Access Journals (Sweden)

Judit Lecina-Diaz

Full Text Available Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1 determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together and (2 ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires. The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn

Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

Science.gov (United States)

Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

2014-01-01

Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme

Parental Reflective Functioning Moderates the Relationship between Difficult Temperament in Infancy and Behavior Problems in Toddlerhood

Science.gov (United States)

Wong, Kristyn; Stacks, Ann M.; Rosenblum, Katherine L.; Muzik, Maria

2017-01-01

This study assessed the links between infant negative affect, parental reflective functioning (RF), and toddler behavior problems in a sample of 84 women and their infants. Mothers provided self-report demographic data and completed the Infant Behavior Questionnaire-Revised during a home visit when the infant was 7 months old. They also completed…

Unusual tumour ablations: report of difficult and interesting cases

OpenAIRE

Mauri, Giovanni; Nicosia, Luca; Varano, Gianluca Maria; Shyn, Paul; Sartori, Sergio; Tombesi, Paola; Di Vece, Francesca; Orsi, Franco; Solbiati, Luigi

2017-01-01

Image-guided ablations are nowadays applied in the treatment of a wide group of diseases and in different organs and regions, and every day interventional radiologists have to face more difficult and unusual cases of tumour ablation. In the present case review, we report four difficult and unusual cases, reporting some tips and tricks for a successful image-guided treatment.

Extreme environment electronics

CERN Document Server

Cressler, John D

2012-01-01

Unfriendly to conventional electronic devices, circuits, and systems, extreme environments represent a serious challenge to designers and mission architects. The first truly comprehensive guide to this specialized field, Extreme Environment Electronics explains the essential aspects of designing and using devices, circuits, and electronic systems intended to operate in extreme environments, including across wide temperature ranges and in radiation-intense scenarios such as space. The Definitive Guide to Extreme Environment Electronics Featuring contributions by some of the world's foremost exp

Adequacy of current systems for monitoring extremity exposures at nuclear power plants

International Nuclear Information System (INIS)

Reece, W.D.; Harty, R.

1985-01-01

In general, only a small portion of workers at commercial nuclear power plants are limited by extremity exposures, and these workers can be readily identified. There seems to be no need for increased badging among the radiation workers. However, those workers who are extremity limited may not be receiving adequate dosimetry. For workers handling compact sources, unless contrary information is available, the tip of the thumb of the dominant hand can be assumed to be the limiting site, and dose to the thumb tip averaged over one square centimeter at the basal layer of the skin should be measured or estimated. As discussed briefly in this paper, the assessment of dose in high gradient fields can be a difficult task. The particular dosimeter studied is a band-aid type composed of a thermoluminescent material embedded in a carbon matrix under 4 mils of plastic. Advantages and disadvantages of the technique are discussed

Early identification of cerebral visual impairments in infants born extremely preterm

NARCIS (Netherlands)

Pel, Johan J M; Dudink, Jeroen; Vonk, Mark; Plaisier, Annemarie; Reiss, Irwin K M; van der Steen, Johannes

2016-01-01

AIM: Children born extremely preterm are at risk of visual processing problems related to brain damage. Damage in visual pathways can remain undetected by conventional magnetic resonance imaging (MRI) and functional consequences cannot always be predicted. The aim of this study was to assess the

A Case Report on Upper Extremity Pain of Cardiac Origin

Directory of Open Access Journals (Sweden)

Turgay Altınbilek

2016-08-01

Full Text Available Upper extremity pain can originate from the musculoskeletal system, or be a reflection of problems originating from various organs. Therefore, it is highly important to perform a detailed clinical evaluation on patients during differential diagnosis. In this case report, we present a 61 year-old male patient who was admitted with pain in both upper extremities and the upper back that presumed to be of cardiac origin following our clinical evaluations. The patient was referred to the cardiology department, where he was diagnosed with coronary heart disease. The patient’s complaints of pain were fully resolved through the application of an intracoronary stent.

How libraries make tough choices in difficult times purposeful abandonment

CERN Document Server

Stern, David

2013-01-01

Contemporary library managers face the need to make difficult choices regarding resource allocation in the modern business environment. How Libraries Make Tough Choices in Difficult Times is a practical guide for library managers, offering techniques to analyze existing and potential services, implement best practices for maximizing existing resources, and utilize pressing financial scenarios in order to justify making difficult reallocation decisions. The book begins by asking the fundamental questions of why, what, and how, moving on to look at how to manage expectations and report to both a

Important plasma problems in astrophysics

International Nuclear Information System (INIS)

Kulsrud, R.M.

1995-01-01

In astrophysics, plasmas occur under very extreme conditions. For example, there are ultrastrong magnetic fields in neutron stars, relativistic plasmas around black holes and in jets, extremely energetic particles such as cosmic rays in the interstellar medium, extremely dense plasmas in accretion disks, and extremely large magnetic Reynolds numbers in the interstellar medium. These extreme limits for astrophysical plasmas make plasma phenomena much simpler to analyze in astrophysics than in the laboratory. An understanding of such phenomena often results in an interesting way, by simply taking the extreme limiting case of a known plasma theory. The author will describe one of the more exciting examples and will attempt to convey the excitement he felt when he was first exposed to it. However, not all plasma astrophysical phenomena are so simple. There are certain important plasma phenomena in astrophysics that have not been so easily resolved. In fact, a resolution of them is blocking significant progress in astrophysical research. They have not yet yielded to attacks by theoretical astrophysicists nor to extensive numerical simulation. The author will attempt to describe one of the more important of these plasma--astrophysical problems, and discuss why its resolution is so important to astrophysics. This significant example is fast, magnetic reconnection. Another significant example is the large-magnetic-Reynolds number magnetohydrodynamics (MHD) dynamos

Benefits of visualization in the mammography problem

DEFF Research Database (Denmark)

Khan, Azam; Breslav, Simon; Glueck, Michael

2015-01-01

Abstract Trying to make a decision between two outcomes, when there is some level of uncertainty, is inherently difficult because it involves probabilistic reasoning. Previous studies have shown that most people do not correctly apply Bayesian inference to solve probabilistic problems for decision...... making under uncertainty. In an effort to improve decision making with Bayesian problems, previous work has studied supplementing the textual description of problems with visualizations, such as graphs and charts. However, results have been varied and generally indicate that visualization...

Use of versapoint to refashion the cervical canal to overcome unusually difficult embryo transfers and improve in-vitro fertilization-embryo transfer outcome: A case series

Directory of Open Access Journals (Sweden)

Nalini Mahajan

2011-01-01

Full Text Available Background : Smooth atraumatic embryo transfer is paramount for the success of in-vitro fertilization (IVF. In difficult cases, cervical canal manipulation may be required. Aim : To see if surgical correction of the cervical canal or cervical canal refashioning could improve ease of embryo transfer. Setting : Private infertility and IVF hospital. Design : Prospective study. Materials and Methods : Patients: 11 women with failed 1-3 IVF cycles with history of extremely difficult embryo transfers (ETs despite undergoing cervical dilatation in the cycle prior to IVF. Interventions : Operative hysteroscopy using Versapoint for refashioning of the cervical canal. Main Outcome Measures : Ease of ET in the subsequent IVF cycle. Secondary outcome measure was to assess reproductive outcome. Results : Easy and atraumatic ET in the IVF cycle after procedure in 100% patients. PR was 46.5%. Conclusions : Use of Versapoint for refashioning the cervical canal can improve the quality of ET and PR.

Emotional distance to so-called difficult patients

DEFF Research Database (Denmark)

Michaelsen, Jette Joost

2012-01-01

Scand J Caring Sci; 2011 Emotional distance to so-called difficult patients Purpose: To explore nurses' relationships with patients they regard as being difficult. How do nurses feel about such patients and relate to them, and what are the consequences for nurse and patient? Design and methods....... Patients' case records were studied and four meetings with the staff were arranged to discuss the findings. Data collection lasted 18 months in all. Findings: Three strategies were identified: persuasion, avoidance (emotional distance), and compromise. Interestingly, in the relationship with a particular...... patient, the avoidance strategy did not necessarily represent the terminal stage, since a nurse could revert to the compromise strategy. Some of the nurses experienced painful emotions regarding these interactions. Conclusions: The avoidance strategy (emotional distance) resulted in important social...

Physical health problems in adults with Prader-Willi syndrome

NARCIS (Netherlands)

Sinnema, M.; Maaskant, M.A.; Schrojenstein Lantman-de Valk, H.M.J. van; Nieuwpoort, I.C. van; Drent, M.L.; Curfs, L.M.G.; Schrander-Stumpel, C.T.R.M.

2011-01-01

Prader-Willi syndrome (PWS) is a genetic disorder which is characterized by severe hypotonia and feeding problems in early infancy. In later childhood and adolescence, this is followed by hyperphagia and extreme obesity if the diet is not strictly controlled. Data on physical health problems in

A modified estimation distribution algorithm based on extreme elitism.

Science.gov (United States)

Gao, Shujun; de Silva, Clarence W

2016-12-01

An existing estimation distribution algorithm (EDA) with univariate marginal Gaussian model was improved by designing and incorporating an extreme elitism selection method. This selection method highlighted the effect of a few top best solutions in the evolution and advanced EDA to form a primary evolution direction and obtain a fast convergence rate. Simultaneously, this selection can also keep the population diversity to make EDA avoid premature convergence. Then the modified EDA was tested by means of benchmark low-dimensional and high-dimensional optimization problems to illustrate the gains in using this extreme elitism selection. Besides, no-free-lunch theorem was implemented in the analysis of the effect of this new selection on EDAs. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Religious extremism as a challenge to tertiary education in Nigeria ...

African Journals Online (AJOL)

Extremists use religion as a shield either for political or economic agenda and manipulate their gullible followers in order to impose their ideology on them. The reality of religious extremism in Nigeria is a challenge to tertiary education to search for a lasting solution that will enable Nigerians overcome the problem and focus ...

Observed increase in extreme daily rainfall in the French Mediterranean

Science.gov (United States)

Ribes, Aurélien; Thao, Soulivanh; Vautard, Robert; Dubuisson, Brigitte; Somot, Samuel; Colin, Jeanne; Planton, Serge; Soubeyroux, Jean-Michel

2018-04-01

We examine long-term trends in the historical record of extreme precipitation events occurring over the French Mediterranean area. Extreme events are considered in terms of their intensity, frequency, extent and precipitated volume. Changes in intensity are analysed via an original statistical approach where the annual maximum rainfall amounts observed at each measurement station are aggregated into a univariate time-series according to their dependence. The mean intensity increase is significant and estimated at + 22% (+ 7 to + 39% at the 90% confidence level) over the 1961-2015 period. Given the observed warming over the considered area, this increase is consistent with a rate of about one to three times that implied by the Clausius-Clapeyron relationship. Changes in frequency and other spatial features are investigated through a Generalised Linear Model. Changes in frequency for events exceeding high thresholds (about 200 mm in 1 day) are found to be significant, typically near a doubling of the frequency, but with large uncertainties in this change ratio. The area affected by severe events and the water volume precipitated during those events also exhibit significant trends, with an increase by a factor of about 4 for a 200 mm threshold, again with large uncertainties. All diagnoses consistently point toward an intensification of the most extreme events over the last decades. We argue that it is difficult to explain the diagnosed trends without invoking the human influence on climate.

Extreme events in the Mediterranean area: A mixed deterministic-statistical approach

International Nuclear Information System (INIS)

Speranza, A.; Tartaglione, N.

2006-01-01

Statistical inference suffers for severe limitations when applied to extreme meteo-climatic events. A fundamental theorem proposes a constructive theory for a universal distribution law (the Generalized Extreme Value distribution) of extremes. Use of this theorem and of its derivations is nowadays quite common. However, when applying it, the selected events should be real extremes. In practical applications a major source of errors is the fact that there is no strict criterion for selecting extremes and, in order to fatten the statistical sample very mild selection criteria are often used. The theorem in question applies to stationary processes. When a trend is introduced, inference becomes even more problematic. Experience shows that any available a priori knowledge concerning the system can play a fundamental role in the analysis, in particular if it lowers the dimensionality of the parameter space to be explored. The inference procedures serve, then, the purpose of testing the reliability of inductive hypothesis, rather than proving them. Within the above general context, analysis of the hypothesis that the frequency and/or intensity of extreme weather events in the Mediterranean area may be changing is proposed. The analysis is based on a combined deterministic-statistical approach: dynamical analysis of intense perturbations is combined with statistical techniques in order to try to formulate the problem in such a way that meaningful conclusion may be achieved

Microwave tomography for functional imaging of extremity soft tissues: feasibility assessment

International Nuclear Information System (INIS)

Semenov, Serguei; Kellam, James; Althausen, Peter; Williams, Thomas; Abubakar, Aria; Bulyshev, Alexander; Sizov, Yuri

2007-01-01

It is important to assess the viability of extremity soft tissues, as this component is often the determinant of the final outcome of fracture treatment. Microwave tomography (MWT) and sensing might be able to provide a fast and mobile assessment of such properties. MWT imaging of extremities possesses a complicated, nonlinear, high dielectric contrast inverse problem of diffraction tomography. There is a high dielectric contrast between bone and soft tissue in the extremities. A contrast between soft tissue abnormalities is less pronounced when compared with the high bone-soft tissue contrast. The goal of this study was to assess the feasibility of MWT for functional imaging of extremity soft tissues, i.e. to detect a relatively small contrast within soft tissues in closer proximity to high contrast boney areas. Both experimental studies and computer simulation were performed. Experiments were conducted using live pigs with compromised blood flow and compartment syndrome within an extremity. A whole 2D tomographic imaging cycle at 1 GHz was computer simulated and images were reconstructed using the Newton, MR-CSI and modified Born methods. Results of experimental studies demonstrate that microwave technology is sensitive to changes in the soft tissue blood content and elevated compartment pressure. It was demonstrated that MWT is feasible for functional imaging of extremity soft tissues, circulatory-related changes, blood flow and elevated compartment pressure

[Correlation between obstructive apnea syndrome and difficult airway in ENT surgery].

Science.gov (United States)

Pera, Marcia Hiray; Tardelli, Maria Angela; Novo, Neil Ferreira; Juliano, Yara; Silva, Helga Cristina Almeida da

2017-12-21

ENT patients with obstructive sleep apnea syndrome have a tendency of collapsing the upper airways in addition to anatomical obstacles. Obstructive sleep apnea syndrome is related to the increased risk of difficult airway and also increased perioperative complications. In order to identify these patients in the preoperative period, the STOP Bang questionnaire has been highlighted because it is summarized and easy to apply. Evaluate through the STOP Bang questionnaire whether patients undergoing ENT surgery with a diagnosis of obstructive sleep apnea syndrome have a higher risk of complications, particularly the occurrence of difficult airway. Measurements of anatomical parameters for difficult airway and questionnaire application for clinical prediction of obstructive sleep apnea syndrome were performed in 48 patients with a previous polysomnographic study. The sample detected difficult airway in about 18.7% of patients, all of them with obstructive sleep apnea syndrome. This group had older age, cervical circumference > 40cm, ASA II and Cormack III/IV. Patients with obstructive sleep apnea syndrome had higher body mass index, cervical circumference, and frequent apnea. In subgroup analysis, the group with severe obstructive sleep apnea syndrome showed a significantly higher SB score compared to patients without this syndrome or with a mild/moderate obstructive sleep apnea syndrome. The STOP Bang questionnaire was not able to predict difficult airway and mild obstructive sleep apnea syndrome, but it identified marked obstructive sleep apnea syndrome. All patients with difficult airway had moderate and marked obstructive sleep apnea syndrome, although this syndrome did not involve difficult airway. The variables Cormack III/IV and BMI greater than 35 Kg.m -2 were able to predict difficult airway and obstructive sleep apnea syndrome, respectively. Copyright © 2017 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Extreme cosmos

CERN Document Server

Gaensler, Bryan

2011-01-01

The universe is all about extremes. Space has a temperature 270°C below freezing. Stars die in catastrophic supernova explosions a billion times brighter than the Sun. A black hole can generate 10 million trillion volts of electricity. And hypergiants are stars 2 billion kilometres across, larger than the orbit of Jupiter. Extreme Cosmos provides a stunning new view of the way the Universe works, seen through the lens of extremes: the fastest, hottest, heaviest, brightest, oldest, densest and even the loudest. This is an astronomy book that not only offers amazing facts and figures but also re

Botulinum therapy for poststroke spasticity of the lower extremity (clinical cases

Directory of Open Access Journals (Sweden)

L. V. Krylova

2014-01-01

Full Text Available The paper deals with the topical problem – the medical rehabilitation of patients with poststroke spasticity. It describes clinical cases of patients with poststroke spasticity of the upper and lower extremities who have received combined therapy using botulinum toxin type A (Botox injections.

Problems in quantum mechanics with solutions

CERN Document Server

d'Emilio, Emilio

2017-01-01

This second edition of an extremely well-received book presents more than 250 nonrelativistic quantum mechanics problems of varying difficulty with the aim of providing students didactic material of proven value, allowing them to test their comprehension and mastery of each subject. The coverage is extremely broad, from themes related to the crisis of classical physics through achievements within the framework of modern atomic physics to lively debated, intriguing aspects relating to, for example, the EPR paradox, the Aharonov-Bohm effect, and quantum teleportation. Compared with the first edition, a variety of improvements have been made and additional topics of interest included, especially focusing on elementary potential scattering. The problems themselves range from standard and straightforward ones to those that are complex but can be considered essential because they address questions of outstanding importance or aspects typically overlooked in primers. The book offers students both an excellent tool f...

Evolving neural networks for strategic decision-making problems.

Science.gov (United States)

Kohl, Nate; Miikkulainen, Risto

2009-04-01

Evolution of neural networks, or neuroevolution, has been a successful approach to many low-level control problems such as pole balancing, vehicle control, and collision warning. However, certain types of problems-such as those involving strategic decision-making-have remained difficult for neuroevolution to solve. This paper evaluates the hypothesis that such problems are difficult because they are fractured: The correct action varies discontinuously as the agent moves from state to state. A method for measuring fracture using the concept of function variation is proposed and, based on this concept, two methods for dealing with fracture are examined: neurons with local receptive fields, and refinement based on a cascaded network architecture. Experiments in several benchmark domains are performed to evaluate how different levels of fracture affect the performance of neuroevolution methods, demonstrating that these two modifications improve performance significantly. These results form a promising starting point for expanding neuroevolution to strategic tasks.

Problem in the surgical correction of long-face with vertical open bite

Directory of Open Access Journals (Sweden)

Coen Pramono D

2005-12-01

Full Text Available Long-face cases usually need both treatment of orthodontic and surgery. The problem appearing in the correction of long-face might be able to be related with some difficult factors such as the crowded teeth and excessive vertical height. A class III malocclusion and excessive open bite can be also followed in long face. This situation might worsen the facial aesthetic condition and increase the difficulty in orthodontic treatment. The orthodontic approach is oriented toward positioning the teeth pre-surgically to facilitate the surgical plan. The form of mandible which has grown in the downward direction in the area of mandible angle makes an extreme vertical open bite. The maxilla is usually presented with a maxillary hypolasia. Double-jaw surgery was done as the correction of the lower jaw alone would produce a flattened face appearance and difficulty in repositioning the mandible to achieve a good facial performance. Several cephalometric points were measured to observe the facial situation progress after surgery. Two cases of longface are reported, and the same surgical treatments were performed and showed different results.

Characteristic aspects of the housing and utilitiescomplex as a difficult organizational and economic system

Directory of Open Access Journals (Sweden)

Butyrin Andrey Yur'evich

2014-02-01

Full Text Available The existing system of housing and utility services functioning is carried out for providing the relevant living environment standards to the population by means of effective functioning of the system of uninterrupted providing housing and utility services according to existing requirements of the Russian standards. Today there is a number of problems, which doesn't allow housing and utility services to function effectively. The main of them is providing high-quality housing and utility services to the population and system of their objective cost assessment. This problem is solved by means of reforming the housing and utility sphere with the possibility of attracting financial resources from private investors. Housing and Utility of the Russian Federation, the basis of which is the housing stock, has a very high specific weight in fixed assets of all the economy.Thus, Housing and Utility is a typical difficult organizational and economic system possessing characteristic features of openness, nonlinearity and dissipativity. In this re-gard, the reasonable approach to Housing and Utility development assumes the need to account for the principles of systemacity, focus and complexity, and also can be based on the existing in the theory and practice of management methodology by difficult organizational and economic systems.Now Housing and Utility development and financing investment programs of the municipal complex organizations is carried out according to the relevant Federal law, according to which the establishment system of limit indexes of change of tariffs and investment extra charges to tariffs for services of the organizations of a municipal complex. Also, innovative ways of energy efficiency increase and decrease in wear of funds is an attempt of the state to develop effective mechanisms of attracting private funds from investors.

The long shadows of the difficult past?

DEFF Research Database (Denmark)

Wolnik, Kevin; Busse, Britta; Tholen, Jochen

2017-01-01

This paper focuses on the question of how young people today evaluate the Second World War today and how this ‘difficult past’ determines their political attitudes. Furthermore, the channels through which the current young generation in Europe is informed about the events dating back to the first...... half of the twentieth century (e.g. parents and grandparents, schools, the media) are examined. The theoretical basis chosen for addressing these questions is the work of Mannheim (1928) on the formation of successive generations, and the theories of collective memories and identities of Eisenstadt...... and his followers. Our empirical evidence comes from a transnational comparison of young people’s memories of this difficult past in Denmark, Finland and Germany. From a historical perspective a comparison of the three countries is particularly interesting as they played different roles during the Second...

Adaptive extremal optimization by detrended fluctuation analysis

International Nuclear Information System (INIS)

Hamacher, K.

2007-01-01

Global optimization is one of the key challenges in computational physics as several problems, e.g. protein structure prediction, the low-energy landscape of atomic clusters, detection of community structures in networks, or model-parameter fitting can be formulated as global optimization problems. Extremal optimization (EO) has become in recent years one particular, successful approach to the global optimization problem. As with almost all other global optimization approaches, EO is driven by an internal dynamics that depends crucially on one or more parameters. Recently, the existence of an optimal scheme for this internal parameter of EO was proven, so as to maximize the performance of the algorithm. However, this proof was not constructive, that is, one cannot use it to deduce the optimal parameter itself a priori. In this study we analyze the dynamics of EO for a test problem (spin glasses). Based on the results we propose an online measure of the performance of EO and a way to use this insight to reformulate the EO algorithm in order to construct optimal values of the internal parameter online without any input by the user. This approach will ultimately allow us to make EO parameter free and thus its application in general global optimization problems much more efficient

Comparison on the Analysis on PM10 Data based on Average and Extreme Series

Directory of Open Access Journals (Sweden)

Mohd Amin Nor Azrita

2018-01-01

Full Text Available The main concern in environmental issue is on extreme phenomena (catastrophic instead of common events. However, most statistical approaches are concerned primarily with the centre of a distribution or on the average value rather than the tail of the distribution which contains the extreme observations. The concept of extreme value theory affords attention to the tails of distribution where standard models are proved unreliable to analyse extreme series. High level of particulate matter (PM10 is a common environmental problem which causes various impacts to human health and material damages. If the main concern is on extreme events, then extreme value analysis provides the best result with significant evidence. The monthly average and monthly maxima PM10 data for Perlis from 2003 to 2014 were analysed. Forecasting for average data is made by Holt-Winters method while return level determine the predicted value of extreme events that occur on average once in a certain period. The forecasting from January 2015 to December 2016 for average data found that the highest forecasted value is 58.18 (standard deviation 18.45 on February 2016 while return level achieved 253.76 units for 24 months (2015-2016 return periods.

Further outlooks: extremely uncomfortable; Die weiteren Aussichten: extrem ungemuetlich

Energy Technology Data Exchange (ETDEWEB)

Resenhoeft, T.

2006-07-01

Climate is changing extremely in the last decades. Scientists dealing with extreme weather, should not only stare at computer simulations. They have also to turn towards psyche, seriously personal experiences, knowing statistics, relativise supposed sensational reports and last not least collecting more data. (GL)

VARIABILITY OF THE INFRARED EXCESS OF EXTREME DEBRIS DISKS

International Nuclear Information System (INIS)

Meng, Huan Y. A.; Rieke, George H.; Su, Kate Y. L.; Rujopakarn, Wiphu; Ivanov, Valentin D.; Vanzi, Leonardo

2012-01-01

Debris disks with extremely large infrared excesses (fractional luminosities >10 –2 ) are rare. Those with ages between 30 and 130 Myr are of interest because their evolution has progressed well beyond that of protoplanetary disks (which dissipate with a timescale of order 3 Myr), yet they represent a period when dynamical models suggest that terrestrial planet building may still be progressing through large, violent collisions that could yield large amounts of debris and large infrared excesses. For example, our Moon was formed through a violent collision of two large protoplanets during this age range. We report two disks around the solar-like stars ID8 and HD 23514 in this age range where the 24 μm infrared excesses vary on timescales of a few years, even though the stars are not variable in the optical. Variations this rapid are difficult to understand if the debris is produced by collisional cascades, as it is for most debris disks. It is possible that the debris in these two systems arises in part from condensates from silicate-rich vapor produced in a series of violent collisions among relatively large bodies. If their evolution is rapid, the rate of detection of extreme excesses would indicate that major collisions may be relatively common in this age range.

Intramuscular vascular malformations of an extremity: findings on MR imaging and pathologic correlation

International Nuclear Information System (INIS)

Kim, E.Y.; Ahn, J.M.; Yoon, H.K.; Do, Y.S.; Kim, S.H.; Choo, S.W.; Choo, I.W.; Suh, Y.L.; Kim, S.M.; Kang, H.S.

1999-01-01

Objective. To analyze the findings of intramuscular vascular malformations of an extremity on MR imaging and to correlate these findings with histopathologic examination.Design and patients. The findings on MR imaging and the medical records of 14 patients with an intramuscular vascular malformation of the extremity were retrospectively studied. All patients underwent surgical excision. Diagnoses were based on the results of pathologic examination. Findings on MR imaging were noted and correlated with the histopathologic findings.Results. Intramuscular vascular malformations of an extremity showed multi-septate, honeycomb, or mixed appearance on MR imaging. Multi-septate areas correlated with dilated and communicating vascular spaces with flattened endothelium. Honeycomb areas corresponded to vascular spaces with inconspicuous small lumina and thickened vascular walls. Areas of increased signal intensity on T2-weighted images were found in all intramuscular vascular malformations. Infiltrative margins were more commonly seen in intramuscular lymphaticovenous malformations. Adherence to neurovascular structures and orientation of the lesion along the long axis of the affected muscle were more commonly seen in intramuscular venous malformations.Conclusions. Intramuscular vascular malformations showed either a multi-septate, honeycomb, or mixed appearance, reflecting the size of the vascular spaces and the thickness of the smooth muscles of the vessel walls. Prediction of the subtype of an intramuscular vascular malformation of an extremity on MR imaging seems to be difficult, although there are associated findings that may be helpful in the differential diagnosis of each subtype. (orig.)

Deformation of extremal black holes from stringy interactions

Science.gov (United States)

Chen, Baoyi; Stein, Leo C.

2018-04-01

Black holes are a powerful setting for studying general relativity and theories beyond GR. However, analytical solutions for rotating black holes in beyond-GR theories are difficult to find because of the complexity of such theories. In this paper, we solve for the deformation to the near-horizon extremal Kerr metric due to two example string-inspired beyond-GR theories: Einstein-dilaton-Gauss-Bonnet and dynamical Chern-Simons theory. We accomplish this by making use of the enhanced symmetry group of NHEK and the weak-coupling limit of EdGB and dCS. We find that the EdGB metric deformation has a curvature singularity, while the dCS metric is regular. From these solutions, we compute orbital frequencies, horizon areas, and entropies. This sets the stage for analytically understanding the microscopic origin of black hole entropy in beyond-GR theories.

Similarity and scaling laws for transient arcs in a strongly accelerating gas flow

International Nuclear Information System (INIS)

Blundell, R.E.; Fang, M.T.C.; Terrill, R.M.

1995-01-01

A high-power electric arc, such as that burning in the interrupter (usually a supersonic nozzle) of a gas-blast circuit-breaker, presents a challenging problem both to theoretical and experimental investigators. The complex non-linear nature of the governing equations and steep radial gradients of arc quantities make analytic and numerical solution of the equations extremely difficult. Experimental work is also difficult due to the extreme physical conditions encountered. It is therefore highly desirable to use similarity theory to extend the limited results available to as wide a variety of arcing conditions as possible

Incidence and predictors of difficult laryngoscopy in 11,219 pediatric anesthesia procedures.

Science.gov (United States)

Heinrich, Sebastian; Birkholz, Torsten; Ihmsen, Harald; Irouschek, Andrea; Ackermann, Andreas; Schmidt, Joachim

2012-08-01

Difficult laryngoscopy in pediatric patients undergoing anesthesia. This retrospective analysis was conducted to investigate incidence and predictors of difficult laryngoscopy in a large cohort of pediatric patients receiving general anesthesia with endotracheal intubation. Young age and craniofacial dysmorphy are predictors for the difficult pediatric airway and difficult laryngoscopy. For difficult laryngoscopy, other general predictors are not yet described. Retrospectively, from a 5-year period, data from 11.219 general anesthesia procedures in pediatric patients with endotracheal intubation using age-adapted Macintosh blades in a single center (university hospital) were analyzed statistically. The overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was 1.35%. In patients younger than 1 year, the incidence of CML III or IV was significantly higher than in the older patients (4.7% vs 0.7%). ASA Physical Status III and IV, a higher Mallampati Score (III and IV) and a low BMI were all associated (P pediatric anesthesia is lower than in adults. Our results show that the risk of difficult laryngoscopy is much higher in patients below 1 year of age, in underweight patients and in ASA III and IV patients. The underlying disease might also contribute to the risk. If the Mallampati score could be obtained, prediction of difficult laryngoscopy seems to be reliable. Our data support the existing recommendations for a specialized anesthesiological team to provide safe anesthesia for infants and neonates. © 2012 Blackwell Publishing Ltd.

Semi-supervised tracking of extreme weather events in global spatio-temporal climate datasets

Science.gov (United States)

Kim, S. K.; Prabhat, M.; Williams, D. N.

2017-12-01

Deep neural networks have been successfully applied to solve problem to detect extreme weather events in large scale climate datasets and attend superior performance that overshadows all previous hand-crafted methods. Recent work has shown that multichannel spatiotemporal encoder-decoder CNN architecture is able to localize events in semi-supervised bounding box. Motivated by this work, we propose new learning metric based on Variational Auto-Encoders (VAE) and Long-Short-Term-Memory (LSTM) to track extreme weather events in spatio-temporal dataset. We consider spatio-temporal object tracking problems as learning probabilistic distribution of continuous latent features of auto-encoder using stochastic variational inference. For this, we assume that our datasets are i.i.d and latent features is able to be modeled by Gaussian distribution. In proposed metric, we first train VAE to generate approximate posterior given multichannel climate input with an extreme climate event at fixed time. Then, we predict bounding box, location and class of extreme climate events using convolutional layers given input concatenating three features including embedding, sampled mean and standard deviation. Lastly, we train LSTM with concatenated input to learn timely information of dataset by recurrently feeding output back to next time-step's input of VAE. Our contribution is two-fold. First, we show the first semi-supervised end-to-end architecture based on VAE to track extreme weather events which can apply to massive scaled unlabeled climate datasets. Second, the information of timely movement of events is considered for bounding box prediction using LSTM which can improve accuracy of localization. To our knowledge, this technique has not been explored neither in climate community or in Machine Learning community.

Categories children find easy and difficult to process in figural analogies

Directory of Open Access Journals (Sweden)

Claire E Stevenson

2014-08-01

Full Text Available Analogical reasoning, the ability to learn about novel phenomena by relating it to structurally similar knowledge, develops with great variability in children. Furthermore, the development of analogical reasoning coincides with greater working memory efficiency and increasing knowledge of the objects and rules present in analogy problems. In figural matrices, a classical form of analogical reasoning assessment, some categories, such as color, appear easier for children to encode and infer than others, such as orientation. Yet, few studies have structurally examined differences in the difficulty of rule-types across different age-groups. This cross-sectional study of figural analogical reasoning examined which underlying rules in figural analogies were easier or more difficult for children to correctly process. School children (N=1422, M=7.0 years, SD=21 months, range 4.5-12.5 years were assessed in analogical reasoning using classical figural matrices and memory measures. The transformations the children had to induce and apply concerned the categories: animal, color, orientation, position, quantity and size. The role of age and memory span on the children’s ability to correctly process each type of transformation was examined using explanatory item response theory models. The results showed that with increasing age and/or greater memory span all transformations were processed more accurately. The what transformations animal, color, quantity and size were easiest, whereas the where transformations orientation and position were most difficult. However, animal, orientation and position became relatively easier with age and increased memory efficiency. The implications are discussed in terms of the development of visual processing in object recognition versus position and motion encoding, the ventral (what and dorsal (where pathways respectively.

Nostalgia: retreat or support in difficult times?

Science.gov (United States)

Batcho, Krystine Irene

2013-01-01

The relationship between nostalgia and coping during difficult times was explored in 2 empirical studies. In the first, 80 undergraduates, 60 women and 20 men, completed the Nostalgia Inventory, a measure of nostalgia proneness, the COPE Inventory, a dispositional measure of strategies for coping with stressful events, and the Childhood Survey, a survey of impressions of childhood experiences. Nostalgia proneness correlated with use of adaptive coping, including emotional social support, expressing emotions, turning to religion, and suppressing competing activities, and did not correlate with escapist or avoidance strategies, including denial, behavioral disengagement, and substance abuse. Nostalgia proneness was related positively to favorable emotional and behavioral childhood experiences and did not correlate with adverse experiences. Favorable impressions of childhood correlated positively with adaptive coping strategies and inversely with dysfunctional ones, whereas unfavorable childhood experiences correlated positively with dysfunctional coping. Regression analyses suggested that the relationship between nostalgia proneness and certain coping strategies may be mediated in part by childhood experiences. In a second study, 100 undergraduates, 86 women and 14 men, completed the Nostalgia Inventory, recalled autobiographical memories that illustrated how childhood is either special or similar to their present life, and rated their likely use of strategies in dealing with 2 hypothetical problems. Nostalgia proneness correlated with emotional and instrumental social coping and with the goal-directed strategies of planning, taking action, and positive reframing. Further research is recommended to explore the role of childhood memories in coping and to identify mechanisms that mediate the relationship between nostalgia and coping.

Fault Diagnosis for Engine Based on Single-Stage Extreme Learning Machine

Directory of Open Access Journals (Sweden)

Fei Gao

2016-01-01

Full Text Available Single-Stage Extreme Learning Machine (SS-ELM is presented to dispose of the mechanical fault diagnosis in this paper. Based on it, the traditional mapping type of extreme learning machine (ELM has been changed and the eigenvectors extracted from signal processing methods are directly regarded as outputs of the network’s hidden layer. Then the uncertainty that training data transformed from the input space to the ELM feature space with the ELM mapping and problem of the selection of the hidden nodes are avoided effectively. The experiment results of diesel engine fault diagnosis show good performance of the SS-ELM algorithm.

Legacies from extreme drought increase ecosystem sensitivity to future extremes

Science.gov (United States)

Smith, M. D.; Knapp, A.; Hoover, D. L.; Avolio, M. L.; Felton, A. J.; Wilcox, K. R.

2016-12-01

Climate extremes, such as drought, are increasing in frequency and intensity, and the ecological consequences of these extreme events can be substantial and widespread. Although there is still much to be learned about how ecosystems will respond to an intensification of drought, even less is known about the factors that determine post-drought recovery of ecosystem function. Such knowledge is particularly important because post-drought recovery periods can be protracted depending on the extent to which key plant populations, community structure and biogeochemical processes are affected. These drought legacies may alter ecosystem function for many years post-drought and may impact future sensitivity to climate extremes. We experimentally imposed two extreme growing season droughts in a central US grassland to assess the impacts of repeated droughts on ecosystem resistance (response) and resilience (recovery). We found that this grassland was not resistant to the first extreme drought due to reduced productivity and differential sensitivity of the co-dominant C4 grass (Andropogon gerardii) and C3 forb (Solidago canadensis) species. This differential sensitivity led to a reordering of species abundances within the plant community. Yet, despite this large shift in plant community composition, which persisted post-drought, the grassland was highly resilient post-drought, due to increased abundance of the dominant C4 grass. Because of this shift to increased C4 grass dominance, we expected that previously-droughted grassland would be more resistant to a second extreme drought. However, contrary to these expectations, previously droughted grassland was more sensitive to drought than grassland that had not experienced drought. Thus, our result suggest that legacies of drought (shift in community composition) may increase ecosystem sensitivity to future extreme events.

Noninvasive carcinoma ex pleomorphic adenoma of the parotid gland: A difficult diagnosis on fine needle aspiration

Directory of Open Access Journals (Sweden)

Theresa Scognamiglio

2015-01-01

Full Text Available Carcinoma ex pleomorphic adenoma (CXPA is a rare epithelial malignancy that arises from a primary or recurrent pleomorphic adenoma (PA. It may be noninvasive (NI or invasive. NI CXPA is extremely rare. Preoperative diagnosis on fine needle aspiration (FNA of CXPA may be difficult and poses a diagnostic challenge to clinicians and pathologists. Herein, we describe the FNA findings of a case of NI-CXPA. A 69-year-old woman presented with rapid enlargement of a stable parotid mass of 25 years. Cytologically, malignant cells were focally associated with metachromatic fibromyxoid matrix that was homogeneous and dense with a vague fibrillary quality. There were cell groups, papillary-like clusters and single malignant cells. The nuclei were pleomorphic with irregularly dispersed chromatin, and the cytoplasm was ill-defined and granular. Nucleoli were small to inconspicuous. Mitoses and necrosis were not seen. Cytological features were not specific for any type of salivary gland carcinoma. The FNA diagnosis was primary high-grade adenocarcinoma of the parotid gland, not otherwise specified. Facial nerve-sparing total parotidectomy was performed, which histologically showed PA interspersed with ducts and nests composed of pleomorphic atypical nuclei surrounded by extensive hyalinization. Single cells were also noted. No capsular infiltration was seen in the entirely sampled tumor. Immunohistochemistry for Ki-67 showed a higher proliferation rate in the malignant ducts and p63 positive cells focally surrounded some of the malignant ducts. Histological diagnosis was NI-CXPA. Accurate diagnosis is important for proper surgical management; however, the preoperative diagnosis of NI-CXPA is difficult to make on FNA.

Noninvasive carcinoma ex pleomorphic adenoma of the parotid gland: A difficult diagnosis on fine needle aspiration

Science.gov (United States)

Scognamiglio, Theresa; Joshi, Rohan; Kuhel, William I.; Tabbara, Sana O.; Rezaei, M. Katayoon; Hoda, Rana S.

2015-01-01

Carcinoma ex pleomorphic adenoma (CXPA) is a rare epithelial malignancy that arises from a primary or recurrent pleomorphic adenoma (PA). It may be noninvasive (NI) or invasive. NI CXPA is extremely rare. Preoperative diagnosis on fine needle aspiration (FNA) of CXPA may be difficult and poses a diagnostic challenge to clinicians and pathologists. Herein, we describe the FNA findings of a case of NI-CXPA. A 69-year-old woman presented with rapid enlargement of a stable parotid mass of 25 years. Cytologically, malignant cells were focally associated with metachromatic fibromyxoid matrix that was homogeneous and dense with a vague fibrillary quality. There were cell groups, papillary-like clusters and single malignant cells. The nuclei were pleomorphic with irregularly dispersed chromatin, and the cytoplasm was ill-defined and granular. Nucleoli were small to inconspicuous. Mitoses and necrosis were not seen. Cytological features were not specific for any type of salivary gland carcinoma. The FNA diagnosis was primary high-grade adenocarcinoma of the parotid gland, not otherwise specified. Facial nerve-sparing total parotidectomy was performed, which histologically showed PA interspersed with ducts and nests composed of pleomorphic atypical nuclei surrounded by extensive hyalinization. Single cells were also noted. No capsular infiltration was seen in the entirely sampled tumor. Immunohistochemistry for Ki-67 showed a higher proliferation rate in the malignant ducts and p63 positive cells focally surrounded some of the malignant ducts. Histological diagnosis was NI-CXPA. Accurate diagnosis is important for proper surgical management; however, the preoperative diagnosis of NI-CXPA is difficult to make on FNA. PMID:25972908

Evaluation of Truview evo2® Laryngoscope In Anticipated Difficult Intubation-A Comparison To Macintosh Laryngoscope

Directory of Open Access Journals (Sweden)

Ishwar Singh

2009-01-01

Full Text Available The aim of the study was to assess and compare laryngoscopic view of Truview evo2 laryngoscope with that of Macintosh laryngoscope in patients with one or more predictors of difficult intubation (PDI. Moreover ease of intubation with Truview evo2 in terms of absolute time requirement was also aimed at. Patients for elective surgery requiring endotracheal intubation were initially assessed for three PDI parameters - modified Mallampati test, thyro-mental distance& Atlanto-occipital (AO joint extension. Patients with cumulative PDI scores of 2 to 5 (in a scale of 0 to 8 were evaluated for Cormack& Lehane (CL grading by Macintosh blade after standard induction. Cases with CL grade of two or more were further evaluated by Truview evo2 laryngoscope and corresponding CL grades were assigned. Intubation attempted under Truview evo2 vision and time required for each successful tracheal intubation (i.e. tracheal intubation completed within one minute was noted. Total fifty cases were studied. The CL grades assigned by Macintosh blade correlated well with the cumulative PDI scores assigned preoperatively, confirming there predictability. Truview evo2 improved laryngeal view in 92 % cases by one or more CL grade. Intubation with Truview evo2 was possible in 88% cases within stipulated time of one minute and mean time of 28.6 seconds with SD of 11.23 was reasonably quick. No significant complication like oro- pharyngeal trauma or extreme pressor response to laryngoscopy was noticed. To conclude, Truview evo2 proved to be a better tool than conventional laryngoscope in anticipated difficult situations.

Report from the 5th Workshop on Extremely Large Databases

Directory of Open Access Journals (Sweden)

Jacek Becla

2012-03-01

Full Text Available The 5th XLDB workshop brought together scientific and industrial users, developers, and researchers of extremely large data and focused on emerging challenges in the healthcare and genomics communities, spreadsheet-based large scale analysis, and challenges in applying statistics to large scale analysis, including machine learning. Major problems discussed were the lack of scalable applications, the lack of expertise in developing solutions, the lack of respect for or attention to big data problems, data volume growth exceeding Moore's Law, poorly scaling algorithms, and poor data quality and integration. More communication between users, developers, and researchers is sorely needed. A variety of future work to help all three groups was discussed, ranging from collecting challenge problems to connecting with particular industrial or academic sectors.

Advanced Dynamically Adaptive Algorithms for Stochastic Simulations on Extreme Scales

Energy Technology Data Exchange (ETDEWEB)

Xiu, Dongbin [Univ. of Utah, Salt Lake City, UT (United States)

2017-03-03

The focus of the project is the development of mathematical methods and high-performance computational tools for stochastic simulations, with a particular emphasis on computations on extreme scales. The core of the project revolves around the design of highly efficient and scalable numerical algorithms that can adaptively and accurately, in high dimensional spaces, resolve stochastic problems with limited smoothness, even containing discontinuities.

Nuclear decommissioning: A problem that won't go away

International Nuclear Information System (INIS)

Lenssen, N.

1999-01-01

The problem of shutdown reactors is growing steadily. As of the beginning of 1999, 94 reactors have been shutdown, only 429 were in operation, meaning that one out of 5.5 reactors ever built was permanently closed. Yet only a handful of these have actually been dismantled. Some countries as Japan and USA, have announced their policies that hey plan to dismantle their reactors in a decade or two after closure. Other countries like Canada or France intend to wait several decades. At the extreme United Kingdom decided to wait more than 100 years. This old shutdown reactors could become a near permanent fixture in some countries. The problem is that, the longer the reactors run, the more radioactive their interiors become, the more difficult, dangerous and expensive is to dismantle the plants, to store and bury the residual radioactive waste. Despite some early real experience with the cost of decommissioning plants, it still remains uncertain just what those costs will be and who will pay. Estimates of the dismantling cost have ranged from 10% of the initial capital investment up to 40% and even 100%. Thus, decommissioning could become the largest remaining expense facing the nuclear industry and the governments who have supported it, particularly if efforts to confine radioactive waste fail. The challenge facing the human societies is to keep nuclear waste including the shuttered plants in isolation for the many millennia that make up the hazardous life of these materials. In this light, no matter what becomes of nuclear power, the nuclear age will continue for a very long time

THE CONTEMPORARY MIGRATION PHENOMENON – THE (UN SOLVED PROBLEM OF THE EUROPEAN COMMUNITY?!

Directory of Open Access Journals (Sweden)

Stelian MANOLACHE

2016-12-01

Full Text Available It is obvious that the migration wave from the Orient is a challenge for Europe and especially for the Catholic and Protestant countries. Its geopolitical, economic, social, cultural, theological and spiritual significance have hardly any competition in the old evolution of the world, the secularisation from the 17th century or the globalisation from the 21st century. From this perspective, it is necessary to study carefully the migration phenomenon in its assembly, trying to present an integrated and multi-criteria diagnosis, especially due to the fact that the migration phenomenon brings closer to each of us the huge and extremely difficult problem of Muslim radicalisation, together with its cohort of terrorist manifestations endangering the most important human right: the right to life. Our study is intentionally intended to evaluate and commensurate, using Orthodox theological criteria, the impact of the actual migration phenomenon, the life of the Muslim community – umma, related to the Christian community from the multicultural European society. We start from the opposed manner the two sides relate to society, understand freedom and the dialogue between religions.

Clinical review: Management of difficult airways

OpenAIRE

Langeron, Olivier; Amour, Julien; Vivien, Benoît; Aubrun, Frédéric

2006-01-01

Difficulties or failure in airway management are still important factors in morbidity and mortality related to anesthesia and intensive care. A patent and secure airway is essential to manage anesthetized or critically ill patients. Oxygenation maintenance during tracheal intubation is the cornerstone of difficult airway management and is always emphasized in guidelines. The occurrence of respiratory adverse events has decreased in claims for injuries due to inadequate airway management mainl...

The Efficacy of Using Diagrams When Solving Probability Word Problems in College

Science.gov (United States)

Beitzel, Brian D.; Staley, Richard K.

2015-01-01

Previous experiments have shown a deleterious effect of visual representations on college students' ability to solve total- and joint-probability word problems. The present experiments used conditional-probability problems, known to be more difficult than total- and joint-probability problems. The diagram group was instructed in how to use tree…

A fire danger rating system for Hawaii

Science.gov (United States)

Robert E. Burgan; Francis M. Fujioka; George H. Hirata

1974-01-01

Extremes in rainfall on the Hawaiian Islands make it difficult to judge forest fire danger conditions. The use of an automatic data collection and computer processing system helps to monitor the problem.

Controlling spatio-temporal extreme events by decreasing the localized energy

International Nuclear Information System (INIS)

Du Lin; Xu Wei; Li Zhanguo; Zhou Bingchang

2011-01-01

The problem of controlling extreme events in spatially extended dynamical systems is investigated in this Letter. Based on observations of the system state, the control technique we proposed locally decreases the spatial energy of the amplitude in the vicinity of the highest burst, without needs of any knowledge or prediction of the system model. Considering the specific Complex Ginzburg-Landau equation, we provide theoretical analysis for designing the localized state feedback controller. More exactly, a simple control law by varying a damping parameter at control region is chose to achieve the control. Numerical simulations and statistic analysis demonstrate that extreme events can be efficiently suppressed by our strategy. In particular, the cost of the control and the tolerant time delay in applying the control is considered in detail. - Highlights: → We propose a local control scheme to suppress spatio-temporal extreme events. → The control is address by decreasing the spatial energy of the system locally. → The detail control law is to apply localized state feedback based on observations. → The cost of the control increases with the size of the control region exponentially. → The tolerant delay of the control is about 5-6 times of lifetime of extreme events.

Musculoskeletal extremity pain in Danish school children - how often and for how long? The CHAMPS study-DK.

Science.gov (United States)

Fuglkjær, Signe; Hartvigsen, Jan; Wedderkopp, Niels; Boyle, Eleanor; Jespersen, Eva; Junge, Tina; Larsen, Lisbeth Runge; Hestbæk, Lise

2017-11-25

Musculoskeletal pain is common in childhood and adolescence, and may be long-lasting and recurrent. Musculoskeletal problems tend to follow adolescents into adulthood, and therefore it is important to design better prevention strategies and early effective treatment. To this end, we need in-depth knowledge about the epidemiology of musculoskeletal extremity problems in this age group, and therefore, the aim of this study was to determine the prevalence, frequency and course of musculoskeletal pain in the upper and lower extremities in a cohort of Danish school children aged 8-14 years at baseline. This was a prospective 3-year school-based cohort study, with information about musculoskeletal pain collected in two ways. Parents answered weekly mobile phone text messages about the presence or absence of musculoskeletal pain in their children, and a clinical consultation was performed in a subset of the children. We found that approximately half the children had lower extremity pain every study year. This pain lasted on average for 8 weeks out of a study year, and the children had on average two and a half episodes per study year. Approximately one quarter of the children had upper extremity pain every study year that lasted on average 3 weeks during a study year, with one and a half episodes being the average. In general, there were more non-traumatic pain episodes compared with traumatic episodes in the lower extremities, whereas the opposite was true in the upper extremities. The most common anatomical pain sites were 'knee' and 'ankle/ft'. Lower extremity pain among children and adolescents is common, recurrent and most often of non-traumatic origin. Upper extremity pain is less common, with fewer and shorter episodes, and usually with a traumatic onset. Girls more frequently reported upper extremity pain, whereas there was no sex-related difference in the lower extremities. The most frequently reported locations were 'knee' and 'ankle/ft'.

Pharmacotherapeutic approaches for treating psoriasis in difficult-to-treat areas.

Science.gov (United States)

Kivelevitch, Dario; Frieder, Jillian; Watson, Ian; Paek, So Yeon; Menter, M Alan

2018-04-01

Despite great therapeutic advancements in psoriasis, four notable difficult-to-treat areas including the scalp, nails, intertriginous (including genitals), and palmoplantar regions, pose a challenge to both physicians and patients. Localized disease of these specific body regions inflicts a significant burden on patients' quality of life and requires an adequate selection of treatments. Areas covered: This manuscript discusses appropriate therapies and important treatment considerations for these difficult-to-treat areas based on the available clinical data from the literature. Expert opinion: Clinical trials assessing therapies for the difficult-to-treat areas have been inadequate. With the first biological clinical trial for genital psoriasis pending publication, it is with hope that other biological agents will be evaluated for region-specific psoriasis. A greater understanding of the genetic and immunologic aspects of regional psoriasis, as well as identification of unique biomarkers, will further guide management decisions. For example, the recent discovery of the IL-36 receptor gene for generalized pustular psoriasis may prove valuable for other forms of psoriasis. Ultimately, identification of the most beneficial treatments for each psoriasis subtype and difficult-to-treat area will provide patients with maximal quality of life.

The Interference of Stereotype Threat with Women's Generation of Mathematical Problem-Solving Strategies.

Science.gov (United States)

Quinn, Diane M.; Spencer, Steven J.

2001-01-01

Investigated whether stereotype threat would depress college women's math performance. In one test, men outperformed women when solving word problems, though women performed equally when problems were converted into numerical equivalents. In another test, participants solved difficult problems in high or reduced stereotype threat conditions. Women…

Global patterns of NDVI-indicated vegetation extremes and their sensitivity to climate extremes

International Nuclear Information System (INIS)

Liu Guo; Liu Hongyan; Yin Yi

2013-01-01

Extremes in climate have significant impacts on ecosystems and are expected to increase under future climate change. Extremes in vegetation could capture such impacts and indicate the vulnerability of ecosystems, but currently have not received a global long-term assessment. In this study, a robust method has been developed to detect significant extremes (low values) in biweekly time series of global normalized difference vegetation index (NDVI) from 1982 to 2006 and thus to acquire a global pattern of vegetation extreme frequency. This pattern coincides with vegetation vulnerability patterns suggested by earlier studies using different methods over different time spans, indicating a consistent mechanism of regulation. Vegetation extremes were found to aggregate in Amazonia and in the semi-arid and semi-humid regions in low and middle latitudes, while they seldom occurred in high latitudes. Among the environmental variables studied, extreme low precipitation has the highest slope against extreme vegetation. For the eight biomes analyzed, these slopes are highest in temperate broadleaf forest and temperate grassland, suggesting a higher sensitivity in these environments. The results presented here contradict the hypothesis that vegetation in water-limited semi-arid and semi-humid regions might be adapted to drought and suggest that vegetation in these regions (especially temperate broadleaf forest and temperate grassland) is highly prone to vegetation extreme events under more severe precipitation extremes. It is also suggested here that more attention be paid to precipitation-induced vegetation changes than to temperature-induced events. (letter)

The problems of simulating electrical power systems within the energy economy

International Nuclear Information System (INIS)

Tuma, I.

1984-01-01

The article examines the problems of developing an electrical power system within the framework of the energy economy as a whole and an energy complex. Whereas in the past it was possible to forecast the development of such a system relatively accurately for ten years or more, the situation is now much more difficult. For the purposes of making forecasts, formalized mathematical methods have been developed and used systematically for many years both in research and in forecasting. For electricity demand, these include balance methods, methods of direct and indirect extrapolation, methods of simple and multiple correlation, methods of international comparison, multicomponent combined models of consumption and so on. The main problem in using them lies in the extremely limited validity of statistically compared interrelationships between a limited number of values in the context of explicitly step-wise changes in the domestic and world economy, in the power production of a country and so forth, which means that these methods do not produce good results. The report analyses the importance of the interrelationship between forecasts of the direction of electrical power development and the power complex as a whole and stresses that the main problem of forecasting the development of electrical power and its individual elements lies in selecting the right approach and deciding how to organize the use of methods in a situation where complex economic conditions operate simultaneously. The article also examines one of the possible ways of improving methods for forecasting energy consumption for the period considered. This consists in using data obtained from the analysis and consideration of factors affecting energy consumption in individual major areas of the economy

Application of a fast skyline computation algorithm for serendipitous searching problems

Science.gov (United States)

Koizumi, Kenichi; Hiraki, Kei; Inaba, Mary

2018-02-01

Skyline computation is a method of extracting interesting entries from a large population with multiple attributes. These entries, called skyline or Pareto optimal entries, are known to have extreme characteristics that cannot be found by outlier detection methods. Skyline computation is an important task for characterizing large amounts of data and selecting interesting entries with extreme features. When the population changes dynamically, the task of calculating a sequence of skyline sets is called continuous skyline computation. This task is known to be difficult to perform for the following reasons: (1) information of non-skyline entries must be stored since they may join the skyline in the future; (2) the appearance or disappearance of even a single entry can change the skyline drastically; (3) it is difficult to adopt a geometric acceleration algorithm for skyline computation tasks with high-dimensional datasets. Our new algorithm called jointed rooted-tree (JR-tree) manages entries using a rooted tree structure. JR-tree delays extend the tree to deep levels to accelerate tree construction and traversal. In this study, we presented the difficulties in extracting entries tagged with a rare label in high-dimensional space and the potential of fast skyline computation in low-latency cell identification technology.

Outcomes for Extremely Premature Infants

Science.gov (United States)

Glass, Hannah C.; Costarino, Andrew T.; Stayer, Stephen A.; Brett, Claire; Cladis, Franklyn; Davis, Peter J.

2015-01-01

Premature birth is a significant cause of infant and child morbidity and mortality. In the United States, the premature birth rate, which had steadily increased during the 1990s and early 2000s, has decreased annually for four years and is now approximately 11.5%. Human viability, defined as gestational age at which the chance of survival is 50%, is currently approximately 23–24 weeks in developed countries. Infant girls, on average, have better outcomes than infant boys. A relatively uncomplicated course in the intensive care nursery for an extremely premature infant results in a discharge date close to the prenatal EDC. Despite technological advances and efforts of child health experts during the last generation, the extremely premature infant (less than 28 weeks gestation) and extremely low birth weight infant (ELBW) (CPAP, mechanical ventilation, and exogenous surfactant increased survival and spurred the development of neonatal intensive care in the 1970s through the early 1990s. Routine administration of antenatal steroids during premature labor improved neonatal mortality and morbidity in the late 1990s. The recognition that chronic postnatal administration of steroids to infants should be avoided may have improved outcomes in the early 2000s. Evidence from recent trials attempting to define the appropriate target for oxygen saturation in preterm infants suggests arterial oxygen saturation between 91–95% (compared to 85–89%) avoids excess mortality. However, final analyses of data from these trials have not been published, so definitive recommendations are still pending The development of neonatal neurocognitive care visits may improve neurocognitive outcomes in this high-risk group. Long-term follow up to detect and address developmental, learning, behavioral, and social problems is critical for children born at these early gestational ages. The striking similarities in response to extreme prematurity in the lung and brain imply that agents and

Fast and Efficient Discrimination of Traveling Salesperson Problem Stimulus Difficulty

Science.gov (United States)

Dry, Matthew J.; Fontaine, Elizabeth L.

2014-01-01

The Traveling Salesperson Problem (TSP) is a computationally difficult combinatorial optimization problem. In spite of its relative difficulty, human solvers are able to generate close-to-optimal solutions in a close-to-linear time frame, and it has been suggested that this is due to the visual system's inherent sensitivity to certain geometric…

Medical Students' Personal Determinants of Overcoming Strategies in Difficult Situations

Directory of Open Access Journals (Sweden)

Veretelnikova Yu.Ya.

2013-03-01

Full Text Available Goal of the research was to study conditionality of overcoming strategies in difficult situations of social interaction by personal representations of attitude to others among medical students. Material and methods. 134 first-year students of Saratov State Medical University n.a. V. I. Razumovsky took part in the comparative diagnostic study. Results. Comparison of average indices of various strategies evidence in coping behaviour allowed revealing statistically significant dependence of coping behaviour modi in difficult situations of social interaction upon types of personal representations of attitude toward others and gender features of forming effective strategies of coping behaviour among medical students. Conclusion. Correlation between coping behaviour modi in difficult situations of social interaction and typology of personal representations of attitudes toward others among medical students was marked.

Weather extremes could affect agriculture

Science.gov (United States)

Balcerak, Ernie

2012-05-01

As Earth's climate warms, agricultural producers will need to adapt. Changes, especially increases in extreme events, are already having an impact on food production, according to speakers at a 1 May session on agriculture and food security at the AGU Science Policy Conference. Christopher Field, director of the Department of Global Ecology at the Carnegie Institution for Science of Washington, D. C., pointed out the complex factors that come into play in understanding food security, including spatially varying controls and stresses, incomplete models, and the potential for threshold responses. Factors that are likely to cause problems include increasing population; increasing preference for meat, which needs more land and energy inputs to produce; climate change; and increasing use of agricultural lands for biomass energy.

Early warnings of extreme winds using the ECMWF Extreme Forecast Index

OpenAIRE

Petroliagis, Thomas I.; Pinson, Pierre

2014-01-01

The European FP7 SafeWind Project aims at developing research towards a European vision of wind power forecasting, which requires advanced meteorological support concerning extreme wind events. This study is focused mainly on early warnings of extreme winds in the early medium-range. Three synoptic stations (airports) of North Germany (Bremen, Hamburg and Hannover) were considered for the construction of time series of daily maximum wind speeds. All daily wind extremes were found to be linked...

High levels of IGF-1 predict difficult intubation of patients with acromegaly.

Science.gov (United States)

Zhang, Yu; Guo, Xiaopeng; Pei, Lijian; Zhang, Zhuhua; Tan, Gang; Xing, Bing

2017-08-01

To investigate the characteristics of difficult intubation and identify novel efficient predictors in patients with acromegaly. Patients with either untreated acromegaly or non-functional pituitary adenomas were enrolled. Patients with acromegaly underwent hormone assays, upper airway computed tomography and magnetic resonance imaging examinations and preoperative overnight polysomnography. The modified Mallampati classification, mouth opening, neck circumference, and neck extension were assessed, and the Cormack-Lehane grades and the time of tracheal intubation were recorded. Patients with acromegaly had a higher incidence of difficult intubation (62.5%). The time of tracheal intubation was prolonged, the neck circumference was enlarged, and the neck extension was confined. In patients with acromegaly and difficult intubation, the insulin-like growth factor 1 levels and apnea/hypoxia index were significantly higher compared to patients without difficult intubation (1115.40 ± 253.73 vs. 791.67 ± 206.62 ng/ml, P = 0.020; 22.17 ± 23.25 vs. 2.47 ± 2.84, P = 0.026, respectively). The bilateral regression analysis revealed that high levels of insulin-like growth factor 1 were an independent risk factor for developing difficult intubation (p = 0.042, Exp B = 1.006). The modified Mallampati classification was positively correlated with apnea/hypoxia index and could be calculated using the following logarithmic equation: MMC = 0.2982 * ln (AHI) + 2.1836. In patients with acromegaly, neck movement is confined, the time of tracheal intubation is prolonged, and the neck circumference is enlarged, and these patients suffer from an increased incidence of difficult intubation (62.5%) during anesthesia induction. The apnea/hypoxia index and insulin-like growth factor 1 levels are both increased in acromegalic patients with difficult intubation, and elevated insulin-like growth factor 1 levels are an independent risk factor of difficult

Medical and psychosocial implications of adolescent extreme obesity - acceptance and effects of structured care, short: Youth with Extreme Obesity Study (YES).

Science.gov (United States)

Wabitsch, Martin; Moss, Anja; Reinehr, Thomas; Wiegand, Susanna; Kiess, Wieland; Scherag, André; Holl, Reinhard; Holle, Rolf; Hebebrand, Johannes

2013-08-29

Prevalence rates of overweight and obesity have increased in German children and adolescents in the last three decades. Adolescents with extreme obesity represent a distinct risk group. On the basis of data obtained by the German Child and Youth Survey (KiGGS) and the German district military offices we estimate that the group of extremely obese adolescents (BMI ≥ 35 kg/m2) currently encompasses approximately 200.000 adolescents aged 14 to 21 yrs. Conventional approaches focusing on weight reduction have largely proven futile for them. In addition, only a small percentage of adolescents with extreme obesity seek actively treatment for obesity while contributing disproportionately strong to health care costs. Because of somatic and psychiatric co-morbidities and social problems adolescents with extreme obesity require special attention within the medical care system. We have initiated the project "Medical and psychosocial implications of adolescents with extreme obesity--acceptance and effects of structured care, short: 'Youths with Extreme Obesity Study (YES)'", which aims at improving the medical care and social support structures for youths with extreme obesity in Germany. We focus on identification of these subjects (baseline examination) and their acceptance of diagnostic and subsequent treatment procedures. In a randomized controlled trial (RCT) we will investigate the effectiveness of a low key group intervention not focusing on weight loss but aimed at the provision of obesity related information, alleviation of social isolation, school and vocational integration and improvement of self-esteem in comparison to a control group treated in a conventional way with focus on weight loss. Interested individuals who fulfill current recommended criteria for weight loss surgery will be provided with a structured preparation and follow-up programs. All subjects will be monitored within a long-term observational study to elucidate medical and psychosocial outcomes

Solving Constraint Satisfaction Problems with Networks of Spiking Neurons.

Science.gov (United States)

Jonke, Zeno; Habenschuss, Stefan; Maass, Wolfgang

2016-01-01

Network of neurons in the brain apply-unlike processors in our current generation of computer hardware-an event-based processing strategy, where short pulses (spikes) are emitted sparsely by neurons to signal the occurrence of an event at a particular point in time. Such spike-based computations promise to be substantially more power-efficient than traditional clocked processing schemes. However, it turns out to be surprisingly difficult to design networks of spiking neurons that can solve difficult computational problems on the level of single spikes, rather than rates of spikes. We present here a new method for designing networks of spiking neurons via an energy function. Furthermore, we show how the energy function of a network of stochastically firing neurons can be shaped in a transparent manner by composing the networks of simple stereotypical network motifs. We show that this design approach enables networks of spiking neurons to produce approximate solutions to difficult (NP-hard) constraint satisfaction problems from the domains of planning/optimization and verification/logical inference. The resulting networks employ noise as a computational resource. Nevertheless, the timing of spikes plays an essential role in their computations. Furthermore, networks of spiking neurons carry out for the Traveling Salesman Problem a more efficient stochastic search for good solutions compared with stochastic artificial neural networks (Boltzmann machines) and Gibbs sampling.

Causes of learning problems in primary school students

Directory of Open Access Journals (Sweden)

Mirkov Snežana I.

2003-01-01

Full Text Available Investigations were conducted on learning problems using the sample of eighth-grade students of primary school (N=335. The respondents opted for one or more than seven offered statements related to: insufficient previous knowledge, insufficient studying, teaching contents (extensive, difficult unintelligible, textbook and teacher’s method of presenting the contents. On the basis of the results obtained, one-third of students have problems in mastering teaching contents of foreign language, physics and chemistry, and about one-fourth in mastering those of history and mathematics. All the mentioned causes of problems are present in varying degrees in some school subjects. The causes of learning problems are markedly present in a larger number of school subjects and they are related to some characteristics of teaching contents. Respondents point out, to a large extent, that teaching contents of technical education are uninteresting. In addition, students’ responses indicate that it is necessary to improve the method for mastering the teaching contents in various school subjects i.e. methods applied in the teaching process. Subjective causes, as pointed out by students, are connected with some of the subjects they have characterized as the most difficult. Unintelligible textbook is stressed to the lowest extent as a cause of learning problems compared to other causes stated for the majority of school subjects.

Preoperative Ultrasonography as a Predictor of Difficult ...

African Journals Online (AJOL)

patient.[8]. On the basis of ultrasound findings, surgeons can select the cases appropriate for their skills aiming at reducing operative complications and minimizing the waste of operative time.[2]. Based on ... bed-more than 20 min. 4. Spillage of bile and ... gallbladder turned out to be difficult laparoscopically. The positive ...

Childhood Obesity: A Heavy Problem

Science.gov (United States)

Costley, Kevin C.; Leggett, Timothy

2010-01-01

The youth of today are faced with a big problem; they are becoming more obese every day. The time of children playing outside all day and being extremely active has been overtaken by the television and video games. The days of sitting down as a family and eating a good healthy meal has been replaced by the rush to the nearest fast food…

Applying behavior analysis to school violence and discipline problems: Schoolwide positive behavior support

Science.gov (United States)

Anderson, Cynthia M.; Kincaid, Donald

2005-01-01

School discipline is a growing concern in the United States. Educators frequently are faced with discipline problems ranging from infrequent but extreme problems (e.g., shootings) to less severe problems that occur at high frequency (e.g., bullying, insubordination, tardiness, and fighting). Unfortunately, teachers report feeling ill prepared to deal effectively with discipline problems in schools. Further, research suggests that many commonly used strategies, such as suspension, expulsion, and other reactive strategies, are not effective for ameliorating discipline problems and may, in fact, make the situation worse. The principles and technology of behavior analysis have been demonstrated to be extremely effective for decreasing problem behavior and increasing social skills exhibited by school children. Recently, these principles and techniques have been applied at the level of the entire school, in a movement termed schoolwide positive behavior support. In this paper we review the tenets of schoolwide positive behavior support, demonstrating the relation between this technology and applied behavior analysis. PMID:22478439

Prevention of Dental Damage and Improvement of Difficult Intubation Using a Paraglossal Technique With a Straight Miller Blade

Directory of Open Access Journals (Sweden)

Yu-Feng Huang

2010-10-01

Full Text Available Patients with diseased teeth, or those who are difficult to intubate, have a higher risk of dental injury during laryngoscopy. We report 3 cases of smooth endotracheal intubation using a paraglossal technique with a straight Miller blade in patients with poor dentition. Three patients with poor dentition were scheduled to undergo surgery under general anesthesia. All patients presented with extremely loose upper central incisors and had lost the other right upper teeth, while micrognathia and prominent, loose upper incisors were noted in 1 case. We elected to use a straight Miller blade using a paraglossal approach. A nasopharyngeal airway was inserted after induction of general anesthesia to facilitate mask ventilation and prevent air leakage from the mask. The Miller blade was then inserted from the right corner of the mouth, avoiding contact with the vulnerable incisors, and advanced along the groove between the tongue and tonsil. The endotracheal tube was subsequently smoothly inserted after obtaining a grade 1 Cormack and Lehane view without dental trauma in all 3 cases. Direct laryngoscopy using the paraglossal straight blade technique avoids dental damage in patients with mobile upper incisors and no right maxillary molars. It is a practical alternative method that differs from the traditional Macintosh laryngoscope in patients with a high risk of dental injury during the procedure. This technique, which provides an improved view of the larynx, might also be helpful with patients in whom intubation is difficult.

[Analysis of difficult problems on European Union laws and regulations of traditional herbal medicinal products].

Science.gov (United States)

Qu, Li-Ping; Zhang, Xiao-Qun; Xiong, Yan; Wang, Yi-Tao; Zou, Wen-Jun

2017-10-01

Registration of Chinese patent medicine in European Union (EU) is of great significance to the internationalization of traditional Chinese medicine as EU market acts as an important position in the global botanical market. In retrospect, the domestic studies on EU regulations of traditional herbal medicinal products have been conducted for more than 10 years, but there is still some cognitive bias and lack of research. In this paper, a review of the relevant research progress and the main misunderstanding problems about Directive 2004/24/EC, like the centralized and decentralized supervision system of traditional herbal medicinal products in the EU, marketing authorization procedures for traditional herbal medicinal products, Community Herbal Monograph and List Entries, would be systematically analyzed, so as to provide reference for the registration of Chinese patent medicine in EU. Copyright© by the Chinese Pharmaceutical Association.

Wireless pilot monitoring system for extreme race conditions.

Science.gov (United States)

Pino, Esteban J; Arias, Diego E; Aqueveque, Pablo; Melin, Pedro; Curtis, Dorothy W

2012-01-01

This paper presents the design and implementation of an assistive device to monitor car drivers under extreme conditions. In particular, this system is designed in preparation for the 2012 Atacama Solar Challenge to be held in the Chilean desert. Actual preliminary results show the feasibility of such a project including physiological and ambient sensors, real-time processing algorithms, wireless data transmission and a remote monitoring station. Implementation details and field results are shown along with a discussion of the main problems found in real-life telemetry monitoring.

Difficult Tracheal Intubation in Obese Gastric Bypass patients

DEFF Research Database (Denmark)

Dohrn, Niclas; Sommer, Thorbjørn; Bisgaard, J.

2016-01-01

Endotracheal intubation is commonly perceived to be more difficult in obese patients than in lean patients. Primarily, we investigated the association between difficult tracheal intubation (DTI) and obesity, and secondarily, the association between DTI and validated scoring systems used to assess...... the airways, the association between DTI and quantities of anesthetics used to induce general anesthesia, and the association between DTI and difficulties with venous and arterial cannulation. This is a monocentric prospective observational clinical study of a consecutive series of 539 obese patients...... was 3.5 % and the patients with DTI were more frequently males, had higher CLC, higher American Society of Anesthesiologists physical status classification (ASA), and noticeably, a lower BMI compared to the patients with easy tracheal intubation. After adjustment with multivariable analyses body mass...

Seeking the best training model for difficult conversations in neonatology.

Science.gov (United States)

Lechner, Beatrice E; Shields, Robin; Tucker, Richard; Bender, G Jesse

2016-05-01

We hypothesize that a formal simulation curriculum prepares neonatology fellows for difficult conversations better than traditional didactics. Single-center neonatology fellowship graduates from 1999 to 2013 were sent a retrospective web-based survey. Some had been exposed to a Difficult Conversations curriculum (simulation group), others had not (no simulation group). The simulation group participated in one workshop annually, consisting of lecture, simulation, and debriefing. Scenarios were customized to year of training. Epoch comparisons were made between the simulation and no simulation groups. Self-rated baseline effectiveness at discussing difficult topics was not different. The simulation group reported more supervised family meetings and feedback after fellow-led meetings. Simulations were rated very positively. The simulation group reported increased comfort levels. Strategic pause and body positioning were specific communication skills more frequently acquired in the simulation group. In both groups, the highest ranked contributors to learning were mentor observation and clinical practice. In the simulation group, simulation and debriefing outranked didactics or other experiences. Simulation-based workshops improve communication skills in high stakes conversations. However, they do not substitute for mentor observation and experience. Establishing a structured simulation-based difficult conversations curriculum refines vital communication skills necessary for the high stakes conversations neonatologists direct in clinical practice.

McKenzie Classification of Extremity Lesions - An audit of primary care patients in 3 clinics

DEFF Research Database (Denmark)

Melbye, Martin

2007-01-01

Syndrome classification based on mechanical testing guides clinical decision making in conservative musculoskeletal care. The aim of this audit was to investigate how many patients presenting with problems in the extremities could be classified into the mechanical syndromes described by Robin Mc...... ranged from 4,5 to 6 years. The mechanical classification  determined by the therapists,  and was recorded on the first three visits. Mechanical classification was based on strict operational definitions. Assessment sheets were collected from each therapist, to determine their adherence...... to the operational definitions. 135 consecutive patients were included over an 18 months period and 28 patients were excluded. Of  the 107 patients with extremity joint problems, 73% were classified into one of McKenzie's mechanical syndromes by therapists trained in the McKenzie method. 34% of patients were...

The difficult issue of age assessment on pedo-pornographic material.

Science.gov (United States)

Cattaneo, Cristina; Ritz-Timme, Stefanie; Gabriel, Peter; Gibelli, Daniele; Giudici, Elena; Poppa, Pasquale; Nohrden, Doerte; Assmann, Sabine; Schmitt, Roland; Grandi, Marco

2009-01-10

The issue of juvenile pornography has seen an increase in the past few years of the number of expert opinions requested to forensic pathologists, paediatricians and other various experts within the forensic and medical fields concerning the age of represented individuals. Regardless of the entity of the problem, no actual method exists which can allow us to give an objective and scientific answer, particularly in the postpubertal stage. Using parameters related to sexual maturation can be very dangerous. Nonetheless some experts still insist with similar types of "expertises". This study aims at verifying the ability of different experts in assessing age of postpubertal individuals represented in pornographic material. Results underline the difficulties and major uncertainties of age evaluation by visual observation of photographic material particularly when the subjects have reached the sexual maturation stage - and therefore in verifying whether the individual is above or below 18 years of age (an important age limit for most European countries as far as this type of crime is concerned). Furthermore the study stresses the need both to search for an alternate approach and to apply extreme caution in judicial evaluation.

Extreme meteorological conditions

International Nuclear Information System (INIS)

Altinger de Schwarzkopf, M.L.

1983-01-01

Different meteorological variables which may reach significant extreme values, such as the windspeed and, in particular, its occurrence through tornadoes and hurricanes that necesarily incide and wich must be taken into account at the time of nuclear power plants' installation, are analyzed. For this kind of study, it is necessary to determine the basic phenomenum of design. Two criteria are applied to define the basic values of design for extreme meteorological variables. The first one determines the expected extreme value: it is obtained from analyzing the recurence of the phenomenum in a convened period of time, wich may be generally of 50 years. The second one determines the extreme value of low probability, taking into account the nuclear power plant's operating life -f.ex. 25 years- and considering, during said lapse, the occurrence probabilities of extreme meteorological phenomena. The values may be determined either by the deterministic method, which is based on the acknowledgement of the fundamental physical characteristics of the phenomena or by the probabilistic method, that aims to the analysis of historical statistical data. Brief comments are made on the subject in relation to the Argentine Republic area. (R.J.S.) [es

Cognitive Development, Genetics Problem Solving, and Genetics Instruction: A Critical Review.

Science.gov (United States)

Smith, Mike U.; Sims, O. Suthern, Jr.

1992-01-01

Review of literature concerning problem solving in genetics and Piagetian stage theory. Authors conclude the research suggests that formal-operational thought is not strictly required for the solution of the majority of classical genetics problems; however, some genetic concepts are difficult for concrete operational students to understand.…

On the Combinatorics of SAT and the Complexity of Planar Problems

DEFF Research Database (Denmark)

Talebanfard, Navid

In this thesis we study several problems arising in Boolean satisfiability ranging from lower bounds for SAT algorithms and proof systems to extremal properties of formulas. The first problem is about construction of hard instances for k-SAT algorithms. For PPSZ algorithm [40] we give the first...

3D seismic experiment in difficult area in Japan; Kokunai nanchiiki ni okeru sanjigen jishin tansa jikken

Energy Technology Data Exchange (ETDEWEB)

Minegishi, M; Nakagami, K; Tanaka, H [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

1997-05-27

Difficult area in this context means an exploration-difficult area supposed to store oil/gas but retarded in exploration for the lack of knowledge about the geological structure due to poor quality of available seismic survey records. Discussed in this paper is a survey conducted into an area covering the southern part of Noshiro-shi, Akita-ken, and Yamamoto-cho, Yamamoto-gun, Akita-ken. An area size suitable for data collection at a target depth of 2500m is determined using an interpretation structure compiled on the basis of available well data and 2D seismic survey data. The plan for siting shock points and receiving points is modified case by case as restrictive factors come to the surface (resulting from the complicated hilly terrain, presence of pipes for agricultural water, etc.). The peculiarities of seismic waves in the terrain are studied through the interpretation of the available well data and 2D seismic survey data for the construction of a 3D velocity model for the confirmation of the appropriateness of the plan for siting shock points and receiving points. Efforts are exerted through enhanced coordination with the contractor to acquire data so that a technologically best design may be won within the limits of the budget. The quality of the data obtained from this experiment is in general better than those obtained from previous experiments, yet many problems remain to be settled in future studies about exploration-difficult areas. 4 refs., 4 figs., 1 tab.

Durango: Scalable Synthetic Workload Generation for Extreme-Scale Application Performance Modeling and Simulation

Energy Technology Data Exchange (ETDEWEB)

Carothers, Christopher D. [Rensselaer Polytechnic Institute (RPI); Meredith, Jeremy S. [ORNL; Blanco, Marc [Rensselaer Polytechnic Institute (RPI); Vetter, Jeffrey S. [ORNL; Mubarak, Misbah [Argonne National Laboratory; LaPre, Justin [Rensselaer Polytechnic Institute (RPI); Moore, Shirley V. [ORNL

2017-05-01

Performance modeling of extreme-scale applications on accurate representations of potential architectures is critical for designing next generation supercomputing systems because it is impractical to construct prototype systems at scale with new network hardware in order to explore designs and policies. However, these simulations often rely on static application traces that can be difficult to work with because of their size and lack of flexibility to extend or scale up without rerunning the original application. To address this problem, we have created a new technique for generating scalable, flexible workloads from real applications, we have implemented a prototype, called Durango, that combines a proven analytical performance modeling language, Aspen, with the massively parallel HPC network modeling capabilities of the CODES framework.Our models are compact, parameterized and representative of real applications with computation events. They are not resource intensive to create and are portable across simulator environments. We demonstrate the utility of Durango by simulating the LULESH application in the CODES simulation environment on several topologies and show that Durango is practical to use for simulation without loss of fidelity, as quantified by simulation metrics. During our validation of Durango's generated communication model of LULESH, we found that the original LULESH miniapp code had a latent bug where the MPI_Waitall operation was used incorrectly. This finding underscores the potential need for a tool such as Durango, beyond its benefits for flexible workload generation and modeling.Additionally, we demonstrate the efficacy of Durango's direct integration approach, which links Aspen into CODES as part of the running network simulation model. Here, Aspen generates the application-level computation timing events, which in turn drive the start of a network communication phase. Results show that Durango's performance scales well when

Difficult intubation: are you prepared for it?

Science.gov (United States)

Balcom, C

1994-01-01

The endotracheal intubation of a patient for surgery requires an anaesthetist who is aided by a skilled and experienced helper. This paper explores reasons why some patients are difficult to intubate. Some are predictable on pre-operative assessment and others are not. Suggestions are given on how the helper is useful to the anaesthetist in this potentially critical situation.

Preoperative Prediction of Difficult Laparoscopic Cholecystectomy: A ...

African Journals Online (AJOL)

Pujahari[2] [Table 1]. The scores were added up to get a total score and the patients were divided into categories of risks based on the total score [Table 2]. The following operative parameters ... The timing was noted from the first port site incision till the last ports closure. ..... Dhanke PS, Vgane SP. Factors predicting difficult ...

Prevention through policy: Urban macroplastic leakages to the marine environment during extreme rainfall events.

Science.gov (United States)

Axelsson, Charles; van Sebille, Erik

2017-11-15

The leakage of large plastic litter (macroplastics) into the ocean is a major environmental problem. A significant fraction of this leakage originates from coastal cities, particularly during extreme rainfall events. As coastal cities continue to grow, finding ways to reduce this macroplastic leakage is extremely pertinent. Here, we explore why and how coastal cities can reduce macroplastic leakages during extreme rainfall events. Using nine global cities as a basis, we establish that while cities actively create policies that reduce plastic leakages, more needs to be done. Nonetheless, these policies are economically, socially and environmentally cobeneficial to the city environment. While the lack of political engagement and economic concerns limit these policies, lacking social motivation and engagement is the largest limitation towards implementing policy. We recommend cities to incentivize citizen and municipal engagement with responsible usage of plastics, cleaning the environment and preparing for future extreme rainfall events. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Educational reform as a dynamic system of problems and solutions: Towards an analytic instrument

NARCIS (Netherlands)

Luttenberg, J.; Carpay, T.; Veugelers, W.

2013-01-01

Large-scale educational reforms are difficult to realize and often fail. In the literature, the course of reform and problems associated with this are frequently discussed. The explanations and recommendations then provided are so diverse that it is difficult to gain a comprehensive overview of what

Diagnosis and management of vascular diseases

International Nuclear Information System (INIS)

Fan Xindong; Zheng Lianzhou

2011-01-01

Vascular disorders mainly include hemangiomas and vascular malformations, and constitute some of the most difficult diagnostic and therapeutic enigmas that can be encountered in the clinical practice. The clinical presentations are extremely variable and can range from an asymptomatic birthmark to life-threatening congestive heart failure. Attributing any of these extremely varied symptoms that a patients may present with to a vascular malformation may be a challenge to the most experienced clinical. This problem is compounded by the extreme rarity of these vascular lesions. If a clinician meets such a patient once every few years, it will be extremely difficult for the physicians to gain a steep learning curve. In such circumstances, it is difficult to formulate a standard of diagnosis and treatment for these vascular disorders. This paper aims to make a comprehensive and detailed description of the classification and diagnosis of the vascular disorders, the common used embolization agents, the concepts of interventional diagnosis and management and the therapies of various hemangiomas and vascular malformations. (authors)

Visual relations children find easy and difficult to process in figural analogies.

Science.gov (United States)

Stevenson, Claire E; Alberto, Rosa A; van den Boom, Max A; de Boeck, Paul A L

2014-01-01

Analogical reasoning, the ability to learn about novel phenomena by relating it to structurally similar knowledge, develops with great variability in children. Furthermore, the development of analogical reasoning coincides with greater working memory efficiency and increasing knowledge of the entities and relations present in analogy problems. In figural matrices, a classical form of analogical reasoning assessment, some features, such as color, appear easier for children to encode and infer than others, such as orientation. Yet, few studies have structurally examined differences in the difficulty of visual relations across different age-groups. This cross-sectional study of figural analogical reasoning examined which underlying rules in figural analogies were easier or more difficult for children to correctly process. School children (N = 1422, M = 7.0 years, SD = 21 months, range 4.5-12.5 years) were assessed in analogical reasoning using classical figural matrices and memory measures. The visual relations the children had to induce and apply concerned the features: animal, color, orientation, position, quantity and size. The role of age and memory span on the children's ability to correctly process each type of relation was examined using explanatory item response theory models. The results showed that with increasing age and/or greater memory span all visual relations were processed more accurately. The "what" visual relations animal, color, quantity and size were easiest, whereas the "where" relations orientation and position were most difficult. However, the "where" visual relations became relatively easier with age and increased memory efficiency. The implications are discussed in terms of the development of visual processing in object recognition vs. position and motion encoding in the ventral ("what") and dorsal ("where") pathways respectively.

Early warnings of extreme winds using the ECMWF Extreme Forecast Index

DEFF Research Database (Denmark)

Petroliagis, Thomas I.; Pinson, Pierre

2014-01-01

The European FP7 SafeWind Project aims at developing research towards a European vision of wind power forecasting, which requires advanced meteorological support concerning extreme wind events. This study is focused mainly on early warnings of extreme winds in the early medium-range. Three synoptic...... regimes. Overall, it becomes clear that the first indications of an extreme wind event might come from the ECMWF deterministic and/or probabilistic components capturing very intense weather systems (possible windstorms) in the medium term. For early warnings, all available EPS Extreme Forecast Index (EFI......) formulations were used, by linking daily maximum wind speeds to EFI values for different forecast horizons. From all possible EFI schemes deployed for issuing early warnings, the highest skill was found for the Gust Factor formulation (EFI-10FGI). Using EFI-10FGI, the corresponding 99% threshold could provide...

Diagnosis, treatment, and rehabilitation of stress fractures in the lower extremity in runners

Directory of Open Access Journals (Sweden)

Kahanov L

2015-03-01

Full Text Available Leamor Kahanov,1 Lindsey E Eberman,2 Kenneth E Games,2 Mitch Wasik2 1College of Health Science, Misericordia University, Dallas, PA, USA; 2Department of Applied Medicine and Rehabilitation, Indiana State University, Terre Haute, IN, USA Abstract: Stress fractures account for between 1% and 20% of athletic injuries, with 80% of stress fractures in the lower extremity. Stress fractures of the lower extremity are common injuries among individuals who participate in endurance, high load-bearing activities such as running, military and aerobic exercise and therefore require practitioner expertise in diagnosis and management. Accurate diagnosis for stress fractures is dependent on the anatomical area. Anatomical regions such as the pelvis, sacrum, and metatarsals offer challenges due to difficulty differentiating pathologies with common symptoms. Special tests and treatment regimes, however, are similar among most stress fractures with resolution between 4 weeks to a year. The most difficult aspect of stress fracture treatment entails mitigating internal and external risk factors. Practitioners should address ongoing risk factors to minimize recurrence. Keywords: medial tibial stress syndrome, stress injury, nonunion stress fracture

Measures taken by the supervisory authority to reduce extremity doses in nuclear medicine facilities in Switzerland

International Nuclear Information System (INIS)

Stritt, Nicolas; Linder, Reto

2011-01-01

In its capacity as the supervisory authority, the Swiss Federal Office of Public Health (SFOPH) has responded to the increase in extremity doses observed in nuclear medicine facilities in Switzerland over the past decade by introducing facility-specific radiation protection audits. These audits have raised the awareness of the staff members concerned with the problem of high extremity doses which arise from handling beta emitters and PET nuclides and prevented any further rise in the extremity doses. However, the evaluation of these audits has also shown that there is still considerable scope for improvement in terms of reducing extremity doses and that further measures are therefore required. Facility-specific and person-specific investigations are currently being conducted with the support of the SFOPH. Their aim is to show facilities which operations during the preparation and application of diagnostic and therapeutic radiopharmaceuticals lead to high extremity doses. This will enable the reduction of extremity doses for nuclear medicine staff as well as ensure that the dose limits are adhered to, in spite of the increasing numbers of examinations.

Full truckload vehicle routing problem with profits

Directory of Open Access Journals (Sweden)

Jian Li

2014-04-01

Full Text Available A new variant of the full truckload vehicle routing problem is studied. In this problem there are more than one delivery points corresponding to the same pickup point, and one order is allowed to be served several times by the same vehicle or different vehicles. For the orders which cannot be assigned because of resource constraint, the logistics company outsources them to other logistics companies at a certain cost. To maximize its profits, logistics company decides which to be transported by private fleet and which to be outsourced. The mathematical model is constructed for the problem. Since the problem is NP-hard and it is difficult to solve the large-scale problems with an exact algorithm, a hybrid genetic algorithm is proposed. Computational results show the effectiveness of the hybrid genetic algorithm.

Defining difficult laryngoscopy findings by using multiple parameters: A machine learning approach

Directory of Open Access Journals (Sweden)

Moustafa Abdelaziz Moustafa

2017-04-01

Conclusion: “Alex Difficult Laryngoscopy Software” (ADLS is a machine learning program for prediction of difficult laryngoscopy. New cases can be entered to the training set thus improving the accuracy of the software.

Difficult Sudoku Puzzles Created by Replica Exchange Monte Carlo Method

OpenAIRE

Watanabe, Hiroshi

2013-01-01

An algorithm to create difficult Sudoku puzzles is proposed. An Ising spin-glass like Hamiltonian describing difficulty of puzzles is defined, and difficult puzzles are created by minimizing the energy of the Hamiltonian. We adopt the replica exchange Monte Carlo method with simultaneous temperature adjustments to search lower energy states efficiently, and we succeed in creating a puzzle which is the world hardest ever created in our definition, to our best knowledge. (Added on Mar. 11, the ...

Language and mathematical problem solving among bilinguals.

Science.gov (United States)

Bernardo, Allan B I

2002-05-01

Does using a bilingual's 1st or 2nd language have an effect on problem solving in semantically rich domains like school mathematics? The author conducted a study to determine whether Filipino-English bilingual students' understanding and solving of word problems in arithmetic differed when the problems were in the students' 1st and 2nd languages. Two groups participated-students whose 1st language was Filipino and students whose 1st language was English-and easy and difficult arithmetic problems were used. The author used a recall paradigm to assess how students understood the word problems and coded the solution accuracy to assess problem solving. The results indicated a 1st-language advantage; that is, the students were better able to understand and solve problems in their 1st language, whether the 1st language was English or Filipino. Moreover, the advantage was more marked with the easy problems. The theoretical and practical implications of the results are discussed.

Prevention through policy : Urban macroplastic leakages to the marine environment during extreme rainfall events

NARCIS (Netherlands)

Axelsson, Charles; van Sebille, Erik

2017-01-01

The leakage of large plastic litter (macroplastics) into the ocean is a major environmental problem. A significant fraction of this leakage originates from coastal cities, particularly during extreme rainfall events. As coastal cities continue to grow, finding ways to reduce this macroplastic

Fistula Campaigns—Are They of Any Benefit?

Directory of Open Access Journals (Sweden)

Cetin Cam

2010-09-01

Conclusion: It is extremely difficult to meet the needs of this global problem with short term programs and volunteers. Directing these efforts to specialist fistula centers and creating reliable scientific evidence should be the main goal.

Narcissistic Personality Disorder

Science.gov (United States)

... this mask of extreme confidence lies a fragile self-esteem that's vulnerable to the slightest criticism. A narcissistic ... another mental health problem. But perceived insults to self-esteem may make it difficult to accept and follow ...

Protection of mineral deposits - a way towards difficult compromises

Science.gov (United States)

Radwanek-Bąk, Barbara; Nieć, Marek

2014-05-01

Mineral deposits are non-renewable natural resources. Their protection and reasonable exploitation are crucial requests resulting from sustainable development principles. Those are also fundamental issues in frame of the intergeneration justice and fairness concept. Protection of mineral resources should be based on interrelated activities: maintaining the possibility of economic use of the identified mineral resources, reduced consumption of mineral resources and ensuring satisfactory results of new prospecting and development of innovative technologies for the mineral resources base. The main problem with guarantee to the use of mineral resources is the accessibility to sites with documented deposits and prospective areas of their occurrence. Often, this contradicts with the interests of residents, planners and needs of the biotic environment protection, thus is often a source of conflicts. Legislative regulations are necessary to mitigate such arguable matters. SWOT analysis carried out with respect to introducing such legal regulations serves to identify the sources of conflicts and difficulties associated with their solution. Consensus reaching is a difficult task, so all decision makers are required to show their mutual understanding and willingness to achieve the goals taking into consideration all benefits for the population (including future generations). Foundations for finding the middle ground are: making the communities aware of their demands on minerals and of indispensable conditions for satisfying these demands; providing complete and accessible information; factual, non-emotional negotiations between decision makers and the public.

From Drought to Flood: Biological Responses of Large River Salmonids and Emergent Management Challenges Under California's Extreme Hydroclimatic Variability

Science.gov (United States)

Anderson, C.

2017-12-01

California's hydroclimatic regime is characterized by extreme interannual variability including periodic, multi-year droughts and winter flooding sequences. Statewide, water years 2012-2016 were characterized by extreme drought followed by likely one of the wettest years on record in water year 2017. Similar drought-flood patterns have occurred multiple times both in the contemporary empirical record and reconstructed climate records. Both the extreme magnitude and rapid succession of these hydroclimatic periods pose difficult challenges for water managers and regulatory agencies responsible for providing instream flows to protect and recover threatened and endangered fish species. Principal among these riverine fish species are federally listed winter-run and spring-run Chinook salmon (Oncorhynchus tshawytscha), Central Valley steelhead (Oncorhynchus mykiss), and the pelagic species Delta smelt (Hypomesus transpacificus). Poor instream conditions from 2012-2016 resulted in extremely low abundance estimates and poor overall fish health, and while fish monitoring results from water year 2017 are too preliminary to draw substantive conclusions, early indicators show continued downward population trends despite the historically wet conditions. This poster evaluates California's hydroclimatic conditions over the past decade and quantifies resultant impacts of the 2012-2016 drought and the extremely wet 2017 water year to both adult escapement and juvenile production estimates in California's major inland salmon rivers over that same time span. We will also examine local, state, and federal regulatory actions both in response to the extreme hydroclimatic variability and in preparation for future drought-flood sequences.

Robust Matching Pursuit Extreme Learning Machines

Directory of Open Access Journals (Sweden)

Zejian Yuan

2018-01-01

Full Text Available Extreme learning machine (ELM is a popular learning algorithm for single hidden layer feedforward networks (SLFNs. It was originally proposed with the inspiration from biological learning and has attracted massive attentions due to its adaptability to various tasks with a fast learning ability and efficient computation cost. As an effective sparse representation method, orthogonal matching pursuit (OMP method can be embedded into ELM to overcome the singularity problem and improve the stability. Usually OMP recovers a sparse vector by minimizing a least squares (LS loss, which is efficient for Gaussian distributed data, but may suffer performance deterioration in presence of non-Gaussian data. To address this problem, a robust matching pursuit method based on a novel kernel risk-sensitive loss (in short KRSLMP is first proposed in this paper. The KRSLMP is then applied to ELM to solve the sparse output weight vector, and the new method named the KRSLMP-ELM is developed for SLFN learning. Experimental results on synthetic and real-world data sets confirm the effectiveness and superiority of the proposed method.

Improving Multi-Instance Multi-Label Learning by Extreme Learning Machine

Directory of Open Access Journals (Sweden)

Ying Yin

2016-05-01

Full Text Available Multi-instance multi-label learning is a learning framework, where every object is represented by a bag of instances and associated with multiple labels simultaneously. The existing degeneration strategy-based methods often suffer from some common drawbacks: (1 the user-specific parameter for the number of clusters may incur the effective problem; (2 SVM may bring a high computational cost when utilized as the classifier builder. In this paper, we propose an algorithm, namely multi-instance multi-label (MIML-extreme learning machine (ELM, to address the problems. To our best knowledge, we are the first to utilize ELM in the MIML problem and to conduct the comparison of ELM and SVM on MIML. Extensive experiments have been conducted on real datasets and synthetic datasets. The results show that MIMLELM tends to achieve better generalization performance at a higher learning speed.

Computing several eigenpairs of Hermitian problems by conjugate gradient iterations

International Nuclear Information System (INIS)

Ovtchinnikov, E.E.

2008-01-01

The paper is concerned with algorithms for computing several extreme eigenpairs of Hermitian problems based on the conjugate gradient method. We analyse computational strategies employed by various algorithms of this kind reported in the literature and identify their limitations. Our criticism is illustrated by numerical tests on a set of problems from electronic structure calculations and acoustics

Schwartz distributions in the Lagrange variational problem

International Nuclear Information System (INIS)

Anton, H.; Bahar, L.Y.

1978-01-01

Schwartz distributions are used to eliminate the necessity of imposing a priori conditions on the class of admissible functions in the Lagrange fixed end-point variational problem. This makes it possible to defer the imposition of conditions on the extremals until such conditions become apparent from physical considerations

Sociodrama: Group Creative Problem Solving in Action.

Science.gov (United States)

Riley, John F.

1990-01-01

Sociodrama is presented as a structured, yet flexible, method of encouraging the use of creative thinking to examine a difficult problem. An example illustrates the steps involved in putting sociodrama into action. Production techniques useful in sociodrama include the soliloquy, double, role reversal, magic shop, unity of opposites, and audience…

Child outcomes of home-visiting for families with complex and multiple problems

NARCIS (Netherlands)

van Assen, Arend; Dickscheit, Jana; Post, Wendy; Grietens, Hans

2016-01-01

Introduction Families with complex and multiple problems are faced with an accumulation of problems across multiple areas of life. Furthermore, these families are often considered to be ‘difficult to treat’. Children and teenagers growing up in these families are exposed to an accumulation of risks

An observational and modeling study of the August 2017 Florida climate extreme event.

Science.gov (United States)

Konduru, R.; Singh, V.; Routray, A.

2017-12-01

A special report on the climate extremes by the Intergovernmental Panel on Climate Change (IPCC) elucidates that the sole cause of disasters is due to the exposure and vulnerability of the human and natural system to the climate extremes. The cause of such a climate extreme could be anthropogenic or non-anthropogenic. Therefore, it is challenging to discern the critical factor of influence for a particular climate extreme. Such kind of perceptive study with reasonable confidence on climate extreme events is possible only if there exist any past case studies. A similar rarest climate extreme problem encountered in the case of Houston floods and extreme rainfall over Florida in August 2017. A continuum of hurricanes like Harvey and Irma targeted the Florida region and caused catastrophe. Due to the rarity of August 2017 Florida climate extreme event, it requires the in-depth study on this case. To understand the multi-faceted nature of the event, a study on the development of the Harvey hurricane and its progression and dynamics is significant. Current article focus on the observational and modeling study on the Harvey hurricane. A global model named as NCUM (The global UK Met office Unified Model (UM) operational at National Center for Medium Range Weather Forecasting, India, was utilized to simulate the Harvey hurricane. The simulated rainfall and wind fields were compared with the observational datasets like Tropical Rainfall Measuring Mission rainfall datasets and Era-Interim wind fields. The National Centre for Environmental Prediction (NCEP) automated tracking system was utilized to track the Harvey hurricane, and the tracks were analyzed statistically for different forecasts concerning the Harvey hurricane track of Joint Typhon Warning Centre. Further, the current study will be continued to investigate the atmospheric processes involved in the August 2017 Florida climate extreme event.

Endotypes of difficult-to-control asthma in inner-city African American children.

Directory of Open Access Journals (Sweden)

K R Brown

Full Text Available African Americans have higher rates of asthma prevalence, morbidity, and mortality in comparison with other racial groups. We sought to characterize endotypes of childhood asthma severity in African American patients in an inner-city pediatric asthma population. Baseline blood neutrophils, blood eosinophils, and 38 serum cytokine levels were measured in a sample of 235 asthmatic children (6-17 years enrolled in the NIAID (National Institute of Allergy and Infectious Diseases-sponsored Asthma Phenotypes in the Inner City (APIC study (ICAC (Inner City Asthma Consortium-19. Cytokines were quantified using a MILLIPLEX panel and analyzed on a Luminex analyzer. Patients were classified as Easy-to-Control or Difficult-to-Control based on the required dose of controller medications over one year of prospective management. A multivariate variable selection procedure was used to select cytokines associated with Difficult-to-Control versus Easy-to-Control asthma, adjusting for age, sex, blood eosinophils, and blood neutrophils. In inner-city African American children, 12 cytokines were significant predictors of Difficult-to-Control asthma (n = 235. CXCL-1, IL-5, IL-8, and IL-17A were positively associated with Difficult-to-Control asthma, while IL-4 and IL-13 were positively associated with Easy-to-Control asthma. Using likelihood ratio testing, it was observed that in addition to blood eosinophils and neutrophils, serum cytokines improved the fit of the model. In an inner-city pediatric population, serum cytokines significantly contributed to the definition of Difficult-to-Control asthma endotypes in African American children. Mixed responses characterized by TH2 (IL-5 and TH17-associated cytokines were associated with Difficult-to-Control asthma. Collectively, these data may contribute to risk stratification of Difficult-to-Control asthma in the African American population.

An Evolutionary Approach for Bilevel Multi-objective Problems

Science.gov (United States)

Deb, Kalyanmoy; Sinha, Ankur

Evolutionary multi-objective optimization (EMO) algorithms have been extensively applied to find multiple near Pareto-optimal solutions over the past 15 years or so. However, EMO algorithms for solving bilevel multi-objective optimization problems have not received adequate attention yet. These problems appear in many applications in practice and involve two levels, each comprising of multiple conflicting objectives. These problems require every feasible upper-level solution to satisfy optimality of a lower-level optimization problem, thereby making them difficult to solve. In this paper, we discuss a recently proposed bilevel EMO procedure and show its working principle on a couple of test problems and on a business decision-making problem. This paper should motivate other EMO researchers to engage more into this important optimization task of practical importance.

Scaling of cross-sections for asymmetric (e,3e) process on helium ...

Indian Academy of Sciences (India)

, India ... (e, 3e) process; five-fold differential cross-section; scaling; helium isoelec- tronic ions. ... ration and experimental control of the target and the intensity related problems make the measurements extremely difficult. The scaling laws of ...

Scintigraphy in diagnostics of algodystrophy in the upper extremity: a review

International Nuclear Information System (INIS)

Zyluk, A.

1995-01-01

Basing on the literature, the information concerning usefulness of the three phase scintigraphy in algodystrophy of the upper extremity, both in diagnostic and etiopathogenetic aspects were presented. Delayed image phase is the examination of the best value in the diagnostics of the condition (the highest sensitivity and specificity). Typical feature of algodystrophy on the bone scan is diffuse periarticular hyperfixation of the tracer, in many joints of the distal part of the extremity. Early phases of scintigraphy are valuable in staging of the disease (distinguishing between 1. and 2. stage), in choice of the method of the treatment (vasoconstrictive or vasodilatative) and in monitoring of the course of the treatment. Haemodynamic changes in dystrophic extremity, appearing in early phases, provide interesting information about the etiopathogenesis of algodystrophy. Prognostic implications of scintigraphy (the prediction of the possibility of algodystrophy developing and prediction of good result of the treatment) were mentioned. The method of quantitative analysis of the scans and the problems concerning the choice of proper region of interesting were discussed. (author). 20 refs, 1 tab

Optimal bounds and extremal trajectories for time averages in dynamical systems

Science.gov (United States)

Tobasco, Ian; Goluskin, David; Doering, Charles

2017-11-01

For systems governed by differential equations it is natural to seek extremal solution trajectories, maximizing or minimizing the long-time average of a given quantity of interest. A priori bounds on optima can be proved by constructing auxiliary functions satisfying certain point-wise inequalities, the verification of which does not require solving the underlying equations. We prove that for any bounded autonomous ODE, the problems of finding extremal trajectories on the one hand and optimal auxiliary functions on the other are strongly dual in the sense of convex duality. As a result, auxiliary functions provide arbitrarily sharp bounds on optimal time averages. Furthermore, nearly optimal auxiliary functions provide volumes in phase space where maximal and nearly maximal trajectories must lie. For polynomial systems, such functions can be constructed by semidefinite programming. We illustrate these ideas using the Lorenz system, producing explicit volumes in phase space where extremal trajectories are guaranteed to reside. Supported by NSF Award DMS-1515161, Van Loo Postdoctoral Fellowships, and the John Simon Guggenheim Foundation.

Ideologies and Discourses: Extreme Narratives in Extreme Metal Music

Directory of Open Access Journals (Sweden)

Bojana Radovanović

2016-10-01

Full Text Available Historically speaking, metal music has always been about provoking a strong reaction. Depending on the characteristics of different sub-genres, one can focus on the sound, technique, visual appearance, and furthermore, the ideologies and ideas that are the foundation for each of the sub-genres. Although the majority of the metal community rejects accusations of being racially intolerant, some ideologies of extreme sub-genres (such as black metal are in fact formed around the ideas of self-conscious elitism expressed through interest in pagan mythology, racism, Nazism and fascism. There has been much interest in the Nazi era within the extreme metal scene thus influencing other sub-genres and artists. The aim of this paper is to examine various appearances of extreme narratives such as Nazism and racism in  different sub-genres of metal, bearing in mind variations dependent on geographical, political, and other factors.

Some unsolved problems in discrete mathematics and mathematical cybernetics

Science.gov (United States)

Korshunov, Aleksei D.

2009-10-01

There are many unsolved problems in discrete mathematics and mathematical cybernetics. Writing a comprehensive survey of such problems involves great difficulties. First, such problems are rather numerous and varied. Second, they greatly differ from each other in degree of completeness of their solution. Therefore, even a comprehensive survey should not attempt to cover the whole variety of such problems; only the most important and significant problems should be reviewed. An impersonal choice of problems to include is quite hard. This paper includes 13 unsolved problems related to combinatorial mathematics and computational complexity theory. The problems selected give an indication of the author's studies for 50 years; for this reason, the choice of the problems reviewed here is, to some extent, subjective. At the same time, these problems are very difficult and quite important for discrete mathematics and mathematical cybernetics. Bibliography: 74 items.

Some unsolved problems in discrete mathematics and mathematical cybernetics

International Nuclear Information System (INIS)

Korshunov, Aleksei D

2009-01-01

There are many unsolved problems in discrete mathematics and mathematical cybernetics. Writing a comprehensive survey of such problems involves great difficulties. First, such problems are rather numerous and varied. Second, they greatly differ from each other in degree of completeness of their solution. Therefore, even a comprehensive survey should not attempt to cover the whole variety of such problems; only the most important and significant problems should be reviewed. An impersonal choice of problems to include is quite hard. This paper includes 13 unsolved problems related to combinatorial mathematics and computational complexity theory. The problems selected give an indication of the author's studies for 50 years; for this reason, the choice of the problems reviewed here is, to some extent, subjective. At the same time, these problems are very difficult and quite important for discrete mathematics and mathematical cybernetics. Bibliography: 74 items.

Extremal surface barriers

International Nuclear Information System (INIS)

Engelhardt, Netta; Wall, Aron C.

2014-01-01

We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy

Self-affirmation improves problem-solving under stress.

Science.gov (United States)

Creswell, J David; Dutcher, Janine M; Klein, William M P; Harris, Peter R; Levine, John M

2013-01-01

High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indicated their perceived chronic stress over the previous month and were randomly assigned to either a self-affirmation or control condition. They then completed 30 difficult remote associate problem-solving items under time pressure in front of an evaluator. Results showed that self-affirmation improved problem-solving performance in underperforming chronically stressed individuals. This research suggests a novel means for boosting problem-solving under stress and may have important implications for understanding how self-affirmation boosts academic achievement in school settings.

Lifetime Reliability Estimate and Extreme Permanent Deformations of Randomly Excited Elasto-Plastic Structures

DEFF Research Database (Denmark)

Nielsen, Søren R.K.; Sørensen, John Dalsgaard; Thoft-Christensen, Palle

1983-01-01

plastic deformation during several loadings can be modelled as a filtered Poisson process. Using the Markov property of this quantity the considered first-passage problem as well as the related extreme distribution problems are then solved numerically, and the results are compared to simulation studies.......A method is presented for life-time reliability' estimates of randomly excited yielding systems, assuming the structure to be safe, when the plastic deformations are confined below certain limits. The accumulated plastic deformations during any single significant loading history are considered...

An application of extreme value theory in estimating liquidity risk

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Sonia Benito Muela

2017-09-01

Full Text Available The last global financial crisis (2007–2008 has highlighted the weaknesses of value at risk (VaR as a measure of market risk, as this metric by itself does not take liquidity risk into account. To address this problem, the academic literature has proposed incorporating liquidity risk into estimations of market risk by adding the VaR of the spread to the risk price. The parametric model is the standard approach used to estimate liquidity risk. As this approach does not generate reliable VaR estimates, we propose estimating liquidity risk using more sophisticated models based on extreme value theory (EVT. We find that the approach based on conditional extreme value theory outperforms the standard approach in terms of accurate VaR estimates and the market risk capital requirements of the Basel Capital Accord.

Integrating Worked Examples into Problem Posing in a Web-Based Learning Environment

Science.gov (United States)

Hsiao, Ju-Yuan; Hung, Chun-Ling; Lan, Yu-Feng; Jeng, Yoau-Chau

2013-01-01

Most students always lack of experience and perceive difficult regarding problem posing. The study hypothesized that worked examples may have benefits for supporting students' problem posing activities. A quasi-experiment was conducted in the context of a business mathematics course for examining the effects of integrating worked examples into…

Trajectories of psychopathology in extremely low birth weight survivors from early adolescence to adulthood: a 20-year longitudinal study.

Science.gov (United States)

Van Lieshout, Ryan J; Ferro, Mark A; Schmidt, Louis A; Boyle, Michael H; Saigal, Saroj; Morrison, Katherine M; Mathewson, Karen J

2018-04-18

Individuals born extremely preterm are exposed to significant perinatal stresses that are associated with an increased risk of psychopathology. However, a paucity of longitudinal studies has prevented the empirical examination of long-term, dynamic effects of perinatal adversity on mental health. Here, internalizing and externalizing problems from adolescence through adulthood were compared in individuals born at extremely low birth weight (ELBW; 2,500 g). Internalizing and externalizing data were collected over 20 years in three waves, during adolescence, young adulthood, and adulthood. Growth models were used to compare longitudinal trajectories in a geographically based sample of 151 ELBW survivors and 137 NBW control participants born between 1977 and 1982 matched for age, sex, and socioeconomic status at age 8. After adjusting for sex, socioeconomic and immigrant status, and family functioning, ELBW survivors failed to show the normative, age-related decline in internalizing problems over time relative to their NBW peers (β = .21; p Self-esteem (but not physical health, IQ, or maternal mood) partially mediated the association between ELBW status and internalizing problems. Extremely low birth weight survivors experienced a blunting of the expected improvement in depression and anxiety from adolescence to adulthood. These findings suggest that altered physiological regulatory systems supporting emotional and cognitive processing may contribute to the maintenance of internalizing problems in this population. © 2018 Association for Child and Adolescent Mental Health.

Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access.

Science.gov (United States)

Costantino, Thomas G; Parikh, Aman K; Satz, Wayne A; Fojtik, John P

2005-11-01

We assess the success rate of emergency physicians in placing peripheral intravenous catheters in difficult-access patients who were unsuccessfully cannulated by emergency nurses. A technique using real-time ultrasonographic guidance by 2 physicians was compared with traditional approaches using palpation and landmark guidance. This was a prospective, systematically allocated study of all patients requiring intravenous access who presented to 2 university hospitals between October 2003 and March 2004. Inclusion criterion was the inability of any available nurse to obtain intravenous access after at least 3 attempts on a subgroup of patients who had a history of difficult intravenous access because of obesity, history of intravenous drug abuse, or chronic medical problems. Exclusion criterion was the need for central venous access. Patients presenting on odd days were allocated to the ultrasonographic-guided group, and those presenting on even days were allocated to the traditional-approach group. Endpoints were successful cannulation, number of sticks, time, and patient satisfaction. Sixty patients were enrolled, 39 on odd days and 21 on even days. Success rate was greater for the ultrasonographic group (97%) versus control (33%), difference in proportions of 64% (95% confidence interval [CI] 39% to 71%). The ultrasonographic group required less overall time (13 minutes versus 30 minutes, for a difference of 17 [95% CI 0.8 to 25.6]), less time to successful cannulation from first percutaneous puncture (4 minutes versus 15 minutes, for a difference of 11 [95% CI 8.2 to 19.4]), and fewer percutaneous punctures (1.7 versus 3.7, for a difference of 2.0 [95% CI 1.27 to 2.82]) and had greater patient satisfaction (8.7 versus 5.7, for a difference of 3.0 [95% CI 1.82 to 4.29]) than the traditional landmark approach. Ultrasonographic-guided peripheral intravenous access is more successful than traditional "blind" techniques, requires less time, decreases the number of

Difficult airway management of children in ambulatory anesthesia: challenges and solutions

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Huang AS

2016-11-01

Full Text Available Andrea S Huang,1 Lindsey Rutland,2 John Hajduk,1 Narasimhan Jagannathan1,2 1Department of Pediatric Anesthesia, Ann and Robert H. Lurie Children’s Hospital of Chicago, 2Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Abstract: As the field of pediatric ambulatory anesthesia expands, anesthesiologists can anticipate encountering an increasing number of patients with expected and unexpected difficult airways. This unique setting and patient population both present challenges in making a decision whether and how to safely proceed in the case of a child with a difficult airway. A host of patient, provider, procedure, and facility-specific factors should be considered. Providers should understand the differences between the pediatric and adult airway, recognize common features and syndromes associated with difficult airways, and be comfortable with different airway equipment and techniques available in the ambulatory setting. Early anticipation, a comprehensive patient assessment, and a clear decision-making algorithm with multiple airway management plans are all critical in safely and effectively managing these patients. These issues and recommendations will be discussed in this comprehensive narrative review. Keywords: difficult airway, pediatrics, ambulatory surgery, airway devices, children

Braving difficult choices alone: children's and adolescents' medical decision making.

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Azzurra Ruggeri

Full Text Available OBJECTIVE: What role should minors play in making medical decisions? The authors examined children's and adolescents' desire to be involved in serious medical decisions and the emotional consequences associated with them. METHODS: Sixty-three children and 76 adolescents were presented with a cover story about a difficult medical choice. Participants were tested in one of four conditions: (1 own informed choice; (2 informed parents' choice to amputate; (3 informed parents' choice to continue a treatment; and (4 uninformed parents' choice to amputate. In a questionnaire, participants were asked about their choices, preference for autonomy, confidence, and emotional reactions when faced with a difficult hypothetical medical choice. RESULTS: Children and adolescents made different choices and participants, especially adolescents, preferred to make the difficult choice themselves, rather than having a parent make it. Children expressed fewer negative emotions than adolescents. Providing information about the alternatives did not affect participants' responses. CONCLUSIONS: Minors, especially adolescents, want to be responsible for their own medical decisions, even when the choice is a difficult one. For the adolescents, results suggest that the decision to be made, instead of the agent making the decision, is the main element influencing their emotional responses and decision confidence. For children, results suggest that they might be less able than adolescents to project how they would feel. The results, overall, draw attention to the need to further investigate how we can better involve minors in the medical decision-making process.

Braving difficult choices alone: children's and adolescents' medical decision making.

Science.gov (United States)

Ruggeri, Azzurra; Gummerum, Michaela; Hanoch, Yaniv

2014-01-01

What role should minors play in making medical decisions? The authors examined children's and adolescents' desire to be involved in serious medical decisions and the emotional consequences associated with them. Sixty-three children and 76 adolescents were presented with a cover story about a difficult medical choice. Participants were tested in one of four conditions: (1) own informed choice; (2) informed parents' choice to amputate; (3) informed parents' choice to continue a treatment; and (4) uninformed parents' choice to amputate. In a questionnaire, participants were asked about their choices, preference for autonomy, confidence, and emotional reactions when faced with a difficult hypothetical medical choice. Children and adolescents made different choices and participants, especially adolescents, preferred to make the difficult choice themselves, rather than having a parent make it. Children expressed fewer negative emotions than adolescents. Providing information about the alternatives did not affect participants' responses. Minors, especially adolescents, want to be responsible for their own medical decisions, even when the choice is a difficult one. For the adolescents, results suggest that the decision to be made, instead of the agent making the decision, is the main element influencing their emotional responses and decision confidence. For children, results suggest that they might be less able than adolescents to project how they would feel. The results, overall, draw attention to the need to further investigate how we can better involve minors in the medical decision-making process.

Braving Difficult Choices Alone: Children's and Adolescents' Medical Decision Making

Science.gov (United States)

Ruggeri, Azzurra; Gummerum, Michaela; Hanoch, Yaniv

2014-01-01

Objective What role should minors play in making medical decisions? The authors examined children's and adolescents' desire to be involved in serious medical decisions and the emotional consequences associated with them. Methods Sixty-three children and 76 adolescents were presented with a cover story about a difficult medical choice. Participants were tested in one of four conditions: (1) own informed choice; (2) informed parents' choice to amputate; (3) informed parents' choice to continue a treatment; and (4) uninformed parents' choice to amputate. In a questionnaire, participants were asked about their choices, preference for autonomy, confidence, and emotional reactions when faced with a difficult hypothetical medical choice. Results Children and adolescents made different choices and participants, especially adolescents, preferred to make the difficult choice themselves, rather than having a parent make it. Children expressed fewer negative emotions than adolescents. Providing information about the alternatives did not affect participants' responses. Conclusions Minors, especially adolescents, want to be responsible for their own medical decisions, even when the choice is a difficult one. For the adolescents, results suggest that the decision to be made, instead of the agent making the decision, is the main element influencing their emotional responses and decision confidence. For children, results suggest that they might be less able than adolescents to project how they would feel. The results, overall, draw attention to the need to further investigate how we can better involve minors in the medical decision-making process. PMID:25084274

Musculoskeletal extremity pain in Danish school children -how often and for how long?

DEFF Research Database (Denmark)

Fuglkjær, Signe; Hartvigsen, Jan; Wedderkopp, Niels

2017-01-01

need in-depth knowledge about the epidemiology of musculoskeletal extremity problems in this age group, and therefore, the aim of this study was to determine the prevalence, frequency and course of musculoskeletal pain in the upper and lower extremities in a cohort of Danish school children aged 8......-14 years at baseline. METHODS: This was a prospective 3-year school-based cohort study, with information about musculoskeletal pain collected in two ways. Parents answered weekly mobile phone text messages about the presence or absence of musculoskeletal pain in their children, and a clinical consultation...... was performed in a subset of the children. RESULTS: We found that approximately half the children had lower extremity pain every study year. This pain lasted on average for 8 weeks out of a study year, and the children had on average two and a half episodes per study year. Approximately one quarter...

Parental Perception and Attitude to Children's Violent Acts in Ife

African Journals Online (AJOL)

Engr E. Egbochukwu

curriculum are, violence makes it difficult for students to learn. Children who are ... esteem, truancy, depression, post-traumatic stress disorder and in extreme cases, suicide ... parents but often this doesn't solve the problem. Many parents also ...

Topology optimization of Channel flow problems

DEFF Research Database (Denmark)

Gersborg-Hansen, Allan; Sigmund, Ole; Haber, R. B.

2005-01-01

function which measures either some local aspect of the velocity field or a global quantity, such as the rate of energy dissipation. We use the finite element method to model the flow, and we solve the optimization problem with a gradient-based math-programming algorithm that is driven by analytical......This paper describes a topology design method for simple two-dimensional flow problems. We consider steady, incompressible laminar viscous flows at low to moderate Reynolds numbers. This makes the flow problem non-linear and hence a non-trivial extension of the work of [Borrvall&Petersson 2002......]. Further, the inclusion of inertia effects significantly alters the physics, enabling solutions of new classes of optimization problems, such as velocity--driven switches, that are not addressed by the earlier method. Specifically, we determine optimal layouts of channel flows that extremize a cost...

Implications of Age-Related Changes in Anatomy for Geriatric-Focused Difficult Airways

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Shih-Yi Lee

2017-09-01

Full Text Available The structure and function surrounding the airway change by the age, which may ultimately result in having anatomic features of difficult airways in the elderly. Hence, we reviewed the literature focusing on the age-related anatomic changes and accordingly to compare the characteristics of difficult airways. With age, teeth wear and loss, protein and collagen synthesis reduction, and bone loss and muscle atrophy results in aged face (chin protrusion, cheek retraction and drooping, jaw restriction (temporo-madibular joint disc displacement and osteoarthritis, neck and back stiffness, and kyphotic deformities (degeneration of spinal articular cartilage, intervertebral discs, and spinal osteoporosis. These age-related changes in anatomy are compatible with the predictors of a difficult airway. We hope that these age-related anatomic approaches will prospectively allow a detailed understanding of the hallmarks resulting in geriatric-focused difficult airways in the future studies.

Occupational performance, pain, and global quality of life in women with upper extremity fractures

DEFF Research Database (Denmark)

Dekkers, Merete Klindt; Nielsen, Tove Lise

2010-01-01

on the COPM and with the COPM satisfaction score, and it can be argued that a finding of a low DASH score in elderly women with upper extremity fractures should be followed up by a referral to occupational therapy. Future studies, preferably follow-up studies, are called for to further explore the multiple......To examine pain, occupational performance problems, and quality of life (QoL) and possible associations between these variables, 41 elderly women with acute pain due to a fracture of the upper extremity were assessed with COPM, DASH, validated questions on pain, and a global question on Qo...

Main problems experienced by children with epidermolysis bullosa : A qualitative study with semi-structured interviews

NARCIS (Netherlands)

van Scheppingen, Corinne; Lettinga, Ant T.; Duipmans, Jose C.; Maathuis, Care G. B.; Jonkman, Marcel F.

2008-01-01

The objective of this study was to identify and specify the problems of children with epidermolysis bullosa. The questions explored were: (i) What do children with epidermolysis bullosa experience as the most difficult problems; (it) What is the impact of these problems on their daily life; and

Constraint satisfaction problems with isolated solutions are hard

International Nuclear Information System (INIS)

Zdeborová, Lenka; Mézard, Marc

2008-01-01

We study the phase diagram and the algorithmic hardness of the random 'locked' constraint satisfaction problems, and compare them to the commonly studied 'non-locked' problems like satisfiability of Boolean formulae or graph coloring. The special property of the locked problems is that clusters of solutions are isolated points. This simplifies significantly the determination of the phase diagram, which makes the locked problems particularly appealing from the mathematical point of view. On the other hand, we show empirically that the clustered phase of these problems is extremely hard from the algorithmic point of view: the best known algorithms all fail to find solutions. Our results suggest that the easy/hard transition (for currently known algorithms) in the locked problems coincides with the clustering transition. These should thus be regarded as new benchmarks of really hard constraint satisfaction problems

The classical Stefan problem basic concepts, modelling and analysis

CERN Document Server

Gupta, SC

2003-01-01

This volume emphasises studies related toclassical Stefan problems. The term "Stefan problem" isgenerally used for heat transfer problems with phase-changes suchas from the liquid to the solid. Stefan problems have somecharacteristics that are typical of them, but certain problemsarising in fields such as mathematical physics and engineeringalso exhibit characteristics similar to them. The term``classical" distinguishes the formulation of these problems fromtheir weak formulation, in which the solution need not possessclassical derivatives. Under suitable assumptions, a weak solutioncould be as good as a classical solution. In hyperbolic Stefanproblems, the characteristic features of Stefan problems arepresent but unlike in Stefan problems, discontinuous solutions areallowed because of the hyperbolic nature of the heat equation. Thenumerical solutions of inverse Stefan problems, and the analysis ofdirect Stefan problems are so integrated that it is difficult todiscuss one without referring to the other. So no...

Solving fuzzy shortest path problem by genetic algorithm

Science.gov (United States)

Syarif, A.; Muludi, K.; Adrian, R.; Gen, M.

2018-03-01

Shortest Path Problem (SPP) is known as one of well-studied fields in the area Operations Research and Mathematical Optimization. It has been applied for many engineering and management designs. The objective is usually to determine path(s) in the network with minimum total cost or traveling time. In the past, the cost value for each arc was usually assigned or estimated as a deteministic value. For some specific real world applications, however, it is often difficult to determine the cost value properly. One way of handling such uncertainty in decision making is by introducing fuzzy approach. With this situation, it will become difficult to solve the problem optimally. This paper presents the investigations on the application of Genetic Algorithm (GA) to a new SPP model in which the cost values are represented as Triangular Fuzzy Number (TFN). We adopts the concept of ranking fuzzy numbers to determine how good the solutions. Here, by giving his/her degree value, the decision maker can determine the range of objective value. This would be very valuable for decision support system in the real world applications.Simulation experiments were carried out by modifying several test problems with 10-25 nodes. It is noted that the proposed approach is capable attaining a good solution with different degree of optimism for the tested problems.

Too difficult to govern? An assessment of the governability of transport biofuels in the EU

International Nuclear Information System (INIS)

Di Lucia, Lorenzo

2013-01-01

Transport biofuels are currently the subject of heated debate in the EU. In the past decade the deployment of these technologies has been justified by claims of attractive environmental, geopolitical and rural development benefits. However, expectations have rapidly turned into deep criticism regarding the sustainability of these technologies and the desirability of pursuing the biofuel path. This situation has generated an on-going controversy and policy deadlock at EU level. This study explores these issues from a governance perspective. Employing the concept of system governability, derived from interactive governance theory, it attempts to shed some light on the problems facing the governance of biofuels and on how the quality of the governance system could be improved. The analysis showed that the governability of the system decreased substantially in the period 2003–2012 due to increasing governing needs and decreasing governing capacity. The quality of the governance system can be improved by (i) improving governing capacity by reducing conflicts among governing actors, advancing consistency among institutions and creating capacity at international and global level; and (ii) promoting advanced technologies and adjusting societal ambitions and expectations regarding biofuels. - highlights: • Biofuels in the EU are significantly more difficult to govern today than in 2003. • This is due to the qualities of the system to be governed and the governing system. • Sustainable biofuel systems are inherently difficult to govern

Improved production of membrane proteins in Escherichia coli by selective codon substitutions

DEFF Research Database (Denmark)

Nørholm, Morten H.H.; Toddo, Stephen; Virkki, Minttu T.I.

2013-01-01

Membrane proteins are extremely challenging to produce in sufficient quantities for biochemical and structural analysis and there is a growing demand for solutions to this problem. In this study we attempted to improve expression of two difficult-to-express coding sequences (araH and narK) for me......Membrane proteins are extremely challenging to produce in sufficient quantities for biochemical and structural analysis and there is a growing demand for solutions to this problem. In this study we attempted to improve expression of two difficult-to-express coding sequences (araH and nar......K) for membrane transporters. For both coding sequences, synonymous codon substitutions in the region adjacent to the AUG start led to significant improvements in expression, whereas multi-parameter sequence optimization of codons throughout the coding sequence failed. We conclude that coding sequences can be re...

Applying Cooperative Techniques in Teaching Problem Solving

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Krisztina Barczi

2013-12-01

Full Text Available Teaching how to solve problems – from solving simple equations to solving difficult competition tasks – has been one of the greatest challenges for mathematics education for many years. Trying to find an effective method is an important educational task. Among others, the question arises as to whether a method in which students help each other might be useful. The present article describes part of an experiment that was designed to determine the effects of cooperative teaching techniques on the development of problem-solving skills.

The difficult doctor? Characteristics of physicians who report frustration with patients: an analysis of survey data

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Garrett Joanne M

2006-10-01

Full Text Available Abstract Background Literature on difficult doctor-patient relationships has focused on the "difficult patient." Our objective was to determine physician and practice characteristics associated with greater physician-reported frustration with patients. Methods We conducted a secondary analysis of the Physicians Worklife Survey, which surveyed a random national sample of physicians. Participants were 1391 family medicine, general internal medicine, and medicine subspecialty physicians. The survey assessed physician and practice characteristics, including stress, depression and anxiety symptoms, practice setting, work hours, case-mix, and control over administrative and clinical practice. Physicians estimated the percentage of their patients who were "generally frustrating to deal with." We categorized physicians by quartile of reported frustrating patients and compared characteristics of physicians in the top quartile to those in the other three quartiles. We used logistic regression to model physician characteristics associated with greater frustration. Results In unadjusted analyses, physicians who reported high frustration with patients were younger (p 55 per week, higher stress, practice in a medicine subspeciality, and greater number of patients with psychosocial problems or substance abuse. Conclusion Personal and practice characteristics of physicians who report high frustration with patients differ from those of other physicians. Understanding factors contributing to physician frustration with patients may allow us to improve the quality of patient-physician relationships.

Extremity dosimetry in medical applications within Europe: an overview of doses and monitoring practices

International Nuclear Information System (INIS)

Donadille, Laurent; Carinou, E.; Ginjaume, M.; Jankowski, J.; Rimpler, A.; Sans Merce, M.; Vanhavere, F.

2008-01-01

Full text: Some activities of the EURADOS Working Group 9 (WG9) related to the radiation protection dosimetry of medical staff were funded by the European Commission in the framework of the CONRAD project, Work Package 7. The objective of WG9 was to promote and co-ordinate research activities for the assessment of occupational exposure to staff at workplaces in therapeutic and diagnostic radiology and nuclear medicine. At these workplaces, from the point of view of the individual monitoring for external radiation, the skin of the fingers is generally the limiting organ. Subgroup 1 of WG9 had as main objective the study of the use of extremity dosemeters in medical radiation fields. The wide variety of radiation field characteristics present in medicine together with the difficulties of measuring a local dose which should be representative for the maximum skin dose using one single detector, makes it difficult to perform extremity dosimetry with an accuracy similar to that of whole-body one. A recent intercomparison organised by WG9 showed that some types of dosemeters significantly underestimate or overestimate skin doses. Subgroup 1 carried out a thorough literature review on extremity dosimetry issues. It covered diagnostic and therapeutic nuclear medicine and PET, interventional radiology and cardiology, and brachytherapy. It has notably pointed out the consensus about the requirement of regular extremity dose monitoring for nuclear medicine and PET, and the great difficulty of measuring extremity doses for procedures in interventional radiology and cardiology, activities for which routine extremity dose monitoring has been found to be poor. Furthermore, information on the status of extremity dosimetry in medical applications and associated monitoring practices was gathered from 7 European countries: France, Germany, Greece, Ireland, Poland, Spain and Switzerland. Interpretation of the data was not easy because of the wide range of procedures involved and also

Technology of magnetic abrasive finishing in machining of difficult-to-machine alloy complex surface

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Fujian MA

2016-10-01

Full Text Available The technology of magnetic abrasive finishing is one of the important finishing technologies. Combining with low-frequency vibration and ultrasonic vibration, it can attain higher precision, quality and efficiency. The characteristics and the related current research of magnetic abrasive finishing, vibration assisted magnetic abrasive finishing and ultrasonic assisted magnetic abrasive finishing are introduced. According to the characteristics of the difficult-to-machine alloy's complex surface, the important problems for further study are presented to realize the finishing of complex surface with the technology of magnetic abrasive finishing, such as increasing the machining efficiency by enhancing the magnetic flux density of machining gap and compounding of magnetic energy and others, establishing of the control function during machining and the process planning method for magnetic abrasive finishing of complex surface under the space geometry restraint of complex surface on magnetic pole, etc.

Decomposition principles applied to the dynamic production and work-force scheduling problem

NARCIS (Netherlands)

Aardal, K.I.; Ari, A.

1987-01-01

One of the most important problems in the production and inventory planning field, is the scheduling of production and work force in a dynamic environment. Although this problem can be formulated as a linear program, it is often quite difficult to solve directly, due to its large scale. Instead, it

Interpersonal Problems and Developmental Trajectories of Binge Eating Disorder

Science.gov (United States)

Blomquist, Kerstin K.; Ansell, Emily B.; White, Marney A.; Masheb, Robin M.; Grilo, Carlos M.

2012-01-01

Objective To explore associations between specific interpersonal constructs and the developmental progression of behaviors leading to binge eating disorder (BED). Method Eighty-four consecutively evaluated, treatment-seeking obese (BMI ≥ 30) men and women with BED were assessed with structured diagnostic and clinical interviews and completed a battery of established measures to assess the current and developmental eating- and weight-related variables as well as interpersonal functioning. Results Using the interpersonal circumplex structural summary method, amplitude, elevation, the affiliation dimension, and the quadratic coefficient for the dominance dimension were associated with eating and weight-related developmental variables. The amplitude coefficient and more extreme interpersonal problems on the dominance dimension (quadratic)—i.e., problems with being extremely high (domineering) or low in dominance (submissive)—were significantly associated with ayounger age at onset of binge eating, BED, and overweight as well as accounted for significant variance in age at binge eating, BED, and overweight onset. Greater interpersonal problems with having an overly affiliative interpersonal style were significantly associated with, and accounted for significant variance in, ayounger age at diet onset. Discussion Findings provide further support for the importance of interpersonal problems among adults with BED and converge with recent work highlighting the importance of specific types of interpersonal problems for understanding heterogeneity and different developmental trajectories of individuals with BED. PMID:22727087

Political Limits to the Processing of Policy Problems

Directory of Open Access Journals (Sweden)

Peter J. May

2013-07-01

Full Text Available This contribution addresses political limits to the processing of policy problems in the United States. Our foci are the forces that limit policymakers' attention to different aspects of problems and how this affects the prospects for problem resolution. We theorize about three sets of forces: interest engagement, linkages among relevant institutions for policymaking, and partisan conflict. We show how the interplay of these forces limits efforts to address complex problems. Based on secondary accounts, we consider these underlying dynamics for ten complex problems. These include the thorny problems of the financial crisis, climate change, and health care; the persistent problems of K-12 education, drug abuse, and food safety; and the looming problems associated with critical infrastructure, the obesity epidemic, ocean health, and terrorism and extreme events. From these accounts we identify different patterns that we label fractured, allied, bureaucratic, and anemic policymaking.

Medical and psychosocial implications of adolescent extreme obesity – acceptance and effects of structured care, short: Youth with Extreme Obesity Study (YES)

Science.gov (United States)

2013-01-01

Background Prevalence rates of overweight and obesity have increased in German children and adolescents in the last three decades. Adolescents with extreme obesity represent a distinct risk group. On the basis of data obtained by the German Child and Youth Survey (KiGGS) and the German district military offices we estimate that the group of extremely obese adolescents (BMI ≥ 35 kg/m2) currently encompasses approximately 200.000 adolescents aged 14 to 21 yrs. Conventional approaches focusing on weight reduction have largely proven futile for them. In addition, only a small percentage of adolescents with extreme obesity seek actively treatment for obesity while contributing disproportionately strong to health care costs. Because of somatic and psychiatric co-morbidities and social problems adolescents with extreme obesity require special attention within the medical care system. We have initiated the project “Medical and psychosocial implications of adolescents with extreme obesity - acceptance and effects of structured care, short: ‘Youths with Extreme Obesity Study (YES)’”, which aims at improving the medical care and social support structures for youths with extreme obesity in Germany. Methods/Design We focus on identification of these subjects (baseline examination) and their acceptance of diagnostic and subsequent treatment procedures. In a randomized controlled trial (RCT) we will investigate the effectiveness of a low key group intervention not focusing on weight loss but aimed at the provision of obesity related information, alleviation of social isolation, school and vocational integration and improvement of self-esteem in comparison to a control group treated in a conventional way with focus on weight loss. Interested individuals who fulfill current recommended criteria for weight loss surgery will be provided with a structured preparation and follow-up programs. All subjects will be monitored within a long-term observational study to

Difficult physician-patient relationships.

Science.gov (United States)

Reifsteck, S W

1998-01-01

Changes in the delivery of health care services in the United States are proceeding so rapidly that many providers are asking how the working relationships between doctors and patients will be effected. Accelerated by cost containment, quality improvement and the growth of managed care, these changes have caused some critics to feel that shorter visits and gatekeeper systems will promote an adversarial relationship between physicians and patients. However, proponents of the changing system feel that better prevention, follow-up care and the attention to customer service these plans can offer will lead to increased patient satisfaction and improved doctor-patient communication. Dedicated to addressing these concerns, the Bayer Institute for Health Care Communication was established in 1987 as a continuing medical education program (CME) focusing on this topic. A half-day workshop on clinician-patient communication to enhance health outcomes was introduced in 1992 and a second workshop, "Difficult' Clinician-Patient Relationships," was developed two years later. The two courses discussed in this article are offered to all physicians, residents, medical students, mid-level providers and other interested staff within the Carle system.

Strategic Models and the Response of Government Agencies to Extreme Emergencies

DEFF Research Database (Denmark)

Casler, Catherine; Pierides, Dean

Government agencies that are tasked with responding to extreme emergencies are constantly battling with the tensions and trade-offs of centralized control versus decentralized decision-making. Many of today’s emergency management organizations are a product of World War II and as such they have...... by the growth of managerialism, these models attend to very different organizational realities from those of the military and of civil service. This is over and above the reduction of specificity within management and organizational theories that already characterizes them. In this paper, we focus on strategy...... and address how military and strategic management models organize the response of government agencies to extreme emergencies whilst also failing to address their core organizational problems. We are interested in the relatively recent creation of centralized organizations like the US Federal Emergency...

Interesting cases which were difficult to diagnose by CT

International Nuclear Information System (INIS)

Ueki, Koji; Okubo, Koichi; Shinohara, Shinji

1981-01-01

Computed tomography (CT) clinically provides us with much more useful diagnostic informations regarding the localization, size, shape, extent and inner structure of the lesions and then in some cases the specific diagnosis can be also obtained by CT alone. However, it is usually difficult to define the longitudinal extent of the lesions, their relation to adjacent tissues, the originated site in enormous lesion and histological type also. At CT examination, it is essential to recognize these drawback and limitation on CT. From these points of view, six interesting cases (i.e. pericardial diverticulum, hepatoma with retroperitoneal metastasis, cholangiohepatoma, afferent loop syndrome, invagination and retroperitoneal malignant schwannoma) which were difficult to diagnose by CT and proved ultimately with operation or autopsy were illustrated with some reviews. (author)

Adaptive learning by extremal dynamics and negative feedback

International Nuclear Information System (INIS)

Bak, Per; Chialvo, Dante R.

2001-01-01

We describe a mechanism for biological learning and adaptation based on two simple principles: (i) Neuronal activity propagates only through the network's strongest synaptic connections (extremal dynamics), and (ii) the strengths of active synapses are reduced if mistakes are made, otherwise no changes occur (negative feedback). The balancing of those two tendencies typically shapes a synaptic landscape with configurations which are barely stable, and therefore highly flexible. This allows for swift adaptation to new situations. Recollection of past successes is achieved by punishing synapses which have once participated in activity associated with successful outputs much less than neurons that have never been successful. Despite its simplicity, the model can readily learn to solve complicated nonlinear tasks, even in the presence of noise. In particular, the learning time for the benchmark parity problem scales algebraically with the problem size N, with an exponent k∼1.4

Difficult management of posterior urethra gunshot wound combined ...

African Journals Online (AJOL)

Posterior urethra gunshot wounds are poorly described in the literature. They are often associated with pelvic vital lesions making difficult early repair of urethral injuries. They can be complicated by urethrorectal fistula, which makes their management more complicated. We report a new case of posterior urethra disruption ...

Videolaryngoscopy versus Fiber-optic Intubation through a Supraglottic Airway in Children with a Difficult Airway: An Analysis from the Multicenter Pediatric Difficult Intubation Registry.

Science.gov (United States)

Burjek, Nicholas E; Nishisaki, Akira; Fiadjoe, John E; Adams, H Daniel; Peeples, Kenneth N; Raman, Vidya T; Olomu, Patrick N; Kovatsis, Pete G; Jagannathan, Narasimhan; Hunyady, Agnes; Bosenberg, Adrian; Tham, See; Low, Daniel; Hopkins, Paul; Glover, Chris; Olutoye, Olutoyin; Szmuk, Peter; McCloskey, John; Dalesio, Nicholas; Koka, Rahul; Greenberg, Robert; Watkins, Scott; Patel, Vikram; Reynolds, Paul; Matuszczak, Maria; Jain, Ranu; Khalil, Samia; Polaner, David; Zieg, Jennifer; Szolnoki, Judit; Sathyamoorthy, Kumar; Taicher, Brad; Riveros Perez, N Ricardo; Bhattacharya, Solmaletha; Bhalla, Tarun; Stricker, Paul; Lockman, Justin; Galvez, Jorge; Rehman, Mohamed; Von Ungern-Sternberg, Britta; Sommerfield, David; Soneru, Codruta; Chiao, Franklin; Richtsfeld, Martina; Belani, Kumar; Sarmiento, Lina; Mireles, Sam; Bilen Rosas, Guelay; Park, Raymond; Peyton, James

2017-09-01

The success rates and related complications of various techniques for intubation in children with difficult airways remain unknown. The primary aim of this study is to compare the success rates of fiber-optic intubation via supraglottic airway to videolaryngoscopy in children with difficult airways. Our secondary aim is to compare the complication rates of these techniques. Observational data were collected from 14 sites after management of difficult pediatric airways. Patient age, intubation technique, success per attempt, use of continuous ventilation, and complications were recorded for each case. First-attempt success and complications were compared in subjects managed with fiber-optic intubation via supraglottic airway and videolaryngoscopy. Fiber-optic intubation via supraglottic airway and videolaryngoscopy had similar first-attempt success rates (67 of 114, 59% vs. 404 of 786, 51%; odds ratio 1.35; 95% CI, 0.91 to 2.00; P = 0.16). In subjects less than 1 yr old, fiber-optic intubation via supraglottic airway was more successful on the first attempt than videolaryngoscopy (19 of 35, 54% vs. 79 of 220, 36%; odds ratio, 2.12; 95% CI, 1.04 to 4.31; P = 0.042). Complication rates were similar in the two groups (20 vs. 13%; P = 0.096). The incidence of hypoxemia was lower when continuous ventilation through the supraglottic airway was used throughout the fiber-optic intubation attempt. In this nonrandomized study, first-attempt success rates were similar for fiber-optic intubation via supraglottic airway and videolaryngoscopy. Fiber-optic intubation via supraglottic airway is associated with higher first-attempt success than videolaryngoscopy in infants with difficult airways. Continuous ventilation through the supraglottic airway during fiber-optic intubation attempts may lower the incidence of hypoxemia.

Some unsolved problems in discrete mathematics and mathematical cybernetics

Energy Technology Data Exchange (ETDEWEB)

Korshunov, Aleksei D [S.L. Sobolev Institute for Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

2009-10-31

There are many unsolved problems in discrete mathematics and mathematical cybernetics. Writing a comprehensive survey of such problems involves great difficulties. First, such problems are rather numerous and varied. Second, they greatly differ from each other in degree of completeness of their solution. Therefore, even a comprehensive survey should not attempt to cover the whole variety of such problems; only the most important and significant problems should be reviewed. An impersonal choice of problems to include is quite hard. This paper includes 13 unsolved problems related to combinatorial mathematics and computational complexity theory. The problems selected give an indication of the author's studies for 50 years; for this reason, the choice of the problems reviewed here is, to some extent, subjective. At the same time, these problems are very difficult and quite important for discrete mathematics and mathematical cybernetics. Bibliography: 74 items.

Difficult to control atopic dermatitis

Science.gov (United States)

2013-01-01

Difficult to control atopic dermatitis (AD) presents a therapeutic challenge and often requires combinations of topical and systemic treatment. Anti-inflammatory treatment of severe AD most commonly includes topical glucocorticosteroids and topical calcineurin antagonists used for exacerbation management and more recently for proactive therapy in selected cases. Topical corticosteroids remain the mainstay of therapy, the topical calcineurin inhibitors tacrolimus and pimecrolimus are preferred in certain locations. Systemic anti-inflammatory treatment is an option for severe refractory cases. Microbial colonization and superinfection contribute to disease exacerbation and thus justify additional antimicrobial / antiseptic treatment. Systemic antihistamines (H1) may relieve pruritus but do not have sufficient effect on eczema. Adjuvant therapy includes UV irradiation preferably of UVA1 wavelength. “Eczema school” educational programs have been proven to be helpful. PMID:23663504

Observation of two-dimensional Faraday waves in extremely shallow depth.

Science.gov (United States)

Li, Xiaochen; Yu, Zhengyue; Liao, Shijun

2015-09-01

A family of two-dimensional Faraday waves in extremely shallow depth (1 mm to 2 mm) of absolute ethanol are observed experimentally using a Hele-Shaw cell that vibrates vertically. The same phenomena are not observed by means of water, ethanol solution, and silicone oil. These Faraday waves are quite different from the traditional ones. These phenomena are helpful to deepen and enrich our understandings about Faraday waves, and besides provide a challenging problem for computational fluid dynamics.

Self-affirmation improves problem-solving under stress.

Directory of Open Access Journals (Sweden)

J David Creswell

Full Text Available High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indicated their perceived chronic stress over the previous month and were randomly assigned to either a self-affirmation or control condition. They then completed 30 difficult remote associate problem-solving items under time pressure in front of an evaluator. Results showed that self-affirmation improved problem-solving performance in underperforming chronically stressed individuals. This research suggests a novel means for boosting problem-solving under stress and may have important implications for understanding how self-affirmation boosts academic achievement in school settings.

Designs of goal-free problems for trigonometry learning

Science.gov (United States)

Retnowati, E.; Maulidya, S. R.

2018-03-01

This paper describes the designs of goal-free problems particularly for trigonometry, which may be considered a difficult topic for high school students.Goal-free problem is an instructional design developed based on a Cognitive load theory (CLT). Within the design, instead of asking students to solve a specific goal of a mathematics problem, the instruction is to solve as many Pythagoras as possible. It was assumed that for novice students, goal-free problems encourage students to pay attention more to the given information and the mathematical principles that can be applied to reveal the unknown variables. Hence, students develop more structured knowledge while solving the goal-free problems. The resulted design may be used in regular mathematics classroom with some adjustment on the difficulty level and the allocated lesson time.

EEG Estimates of Cognitive Workload and Engagement Predict Math Problem Solving Outcomes

Science.gov (United States)

Beal, Carole R.; Galan, Federico Cirett

2012-01-01

In the present study, the authors focused on the use of electroencephalography (EEG) data about cognitive workload and sustained attention to predict math problem solving outcomes. EEG data were recorded as students solved a series of easy and difficult math problems. Sequences of attention and cognitive workload estimates derived from the EEG…

DETERMINATION OF THE TIME LIMITS OF ELIGIBILITY IN A STATE OF EXTREME NECESSITY

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Vyacheslav Victorovich Naumov

2015-12-01

Full Text Available Up to now the limits of eligibility of extreme necessity were not the subject of independent research.The problems of definition of the time limits of p eligibility are considered in this article based on the scientific and monographic literature analysis. Relevance of the considered matter is defined by the fact that the correct establishment of time limits of eligibility of act is of great importance in the law enforcement activity in order to establish the non-delinquency of act in state of extreme necessity. The purpose of this research is the analysis of definition of time limits of extreme necessity eligibility and drawing proposals on this basis for improvement of legislative regulations and existing laws enforcement efficiency with regards to extreme necessity. Research methods: dialectic, formal-logical, system. The author empha-sizes the eligibility limits of admissible harm and the temporary limits. When determining the time limits the author emphasizes the following criteria: the value of danger, intensity of actions, and also identifies an "initial" and "final" moments in the defense of legally protected interests. The improvement of the existing legisla-tion was proposed based on the carried-out analysis.

Genetic evidence of multiple loci in dystocia - difficult labour

Directory of Open Access Journals (Sweden)

Westgren Magnus

2010-06-01

Full Text Available Abstract Background Dystocia, difficult labour, is a common but also complex problem during childbirth. It can be attributed to either weak contractions of the uterus, a large infant, reduced capacity of the pelvis or combinations of these. Previous studies have indicated that there is a genetic component in the susceptibility of experiencing dystocia. The purpose of this study was to identify susceptibility genes in dystocia. Methods A total of 104 women in 47 families were included where at least two sisters had undergone caesarean section at a gestational length of 286 days or more at their first delivery. Study of medical records and a telephone interview was performed to identify subjects with dystocia. Whole-genome scanning using Affymetrix genotyping-arrays and non-parametric linkage (NPL analysis was made in 39 women exhibiting the phenotype of dystocia from 19 families. In 68 women re-sequencing was performed of candidate genes showing suggestive linkage: oxytocin (OXT on chromosome 20 and oxytocin-receptor (OXTR on chromosome 3. Results We found a trend towards linkage with suggestive NPL-score (3.15 on chromosome 12p12. Suggestive linkage peaks were observed on chromosomes 3, 4, 6, 10, 20. Re-sequencing of OXT and OXTR did not reveal any causal variants. Conclusions Dystocia is likely to have a genetic component with variations in multiple genes affecting the patient outcome. We found 6 loci that could be re-evaluated in larger patient cohorts.

Genetic evidence of multiple loci in dystocia - difficult labour

Science.gov (United States)

2010-01-01

Background Dystocia, difficult labour, is a common but also complex problem during childbirth. It can be attributed to either weak contractions of the uterus, a large infant, reduced capacity of the pelvis or combinations of these. Previous studies have indicated that there is a genetic component in the susceptibility of experiencing dystocia. The purpose of this study was to identify susceptibility genes in dystocia. Methods A total of 104 women in 47 families were included where at least two sisters had undergone caesarean section at a gestational length of 286 days or more at their first delivery. Study of medical records and a telephone interview was performed to identify subjects with dystocia. Whole-genome scanning using Affymetrix genotyping-arrays and non-parametric linkage (NPL) analysis was made in 39 women exhibiting the phenotype of dystocia from 19 families. In 68 women re-sequencing was performed of candidate genes showing suggestive linkage: oxytocin (OXT) on chromosome 20 and oxytocin-receptor (OXTR) on chromosome 3. Results We found a trend towards linkage with suggestive NPL-score (3.15) on chromosome 12p12. Suggestive linkage peaks were observed on chromosomes 3, 4, 6, 10, 20. Re-sequencing of OXT and OXTR did not reveal any causal variants. Conclusions Dystocia is likely to have a genetic component with variations in multiple genes affecting the patient outcome. We found 6 loci that could be re-evaluated in larger patient cohorts. PMID:20587075

Comparison of different tests to determine difficult intubation in pediatric patients

Directory of Open Access Journals (Sweden)

Mehmet Turan Inal

2014-12-01

Full Text Available Background: The difficulties with airway management is the main reason for pediatric anesthesia-related morbidity and mortality. Objective: To assess the value of modified Mallampati test, Upper-Lip-Bite test, thyromental distance and the ratio of height to thyromental distance to predict difficult intubation in pediatric patients. Design: Prospective analysis. Measurements and results: Data were collected from 5 to 11 years old 250 pediatric patients requiring tracheal intubation. The Cormack and Lehane classification was used to evaluate difficult laryngoscopy. Sensitivity, specificity, positive predictive value and AUC values for each test were measured. Results: The sensitivity and specificity of modified Mallampati test were 76.92% and 95.54%, while those for ULBT were 69.23% and 97.32%. The optimal cutoff point for the ratio of height to thyromental distance and thyromental distance for predicting difficult laryngoscopy was 23.5 (sensitivity, 57.69%; specificity, 86.61% and 5.5 cm (sensitivity, 61.54%; specificity, 99.11%. The modified Mallampati was the most sensitive of the tests. The ratio of height to thyromental distance was the least sensitive test. Conclusion: These results suggested that the modified Mallampati and Upper-Lip-Bite tests may be useful in pediatric patients for predicting difficult intubation.

Satellite skill in detecting extreme episodes in near-surface air quality

Science.gov (United States)

Ruiz, D. J.; Prather, M. J.

2017-12-01

Ozone (O3) contributes to ambient air pollution, adversely affecting public health, agriculture, and ecosystems. Reliable, long-term, densely distributed surface networks are required to establish the scale, intensity and repeatability of major pollution events (designated here in a climatological sense as air quality extremes, AQX as defined in Schnell's work). Regrettably, such networks are only available for North America (NA) and Europe (EU), which does not include many populated regions where the deaths associated with air pollution exposure are alarmingly high. Directly measuring surface pollutants from space without lidar is extremely difficult. Mapping of daily pollution events requires cross-track nadir scanners and these have limited sensitivity to surface O3 levels. This work examines several years of coincident surface and OMI satellite measurements over NA-EU, in combination with a chemistry-transport model (CTM) hindcast of that period to understand how the large-scale AQX episodes may extend into the free troposphere and thus be more amenable to satellite mapping. We show how extreme NA-EU episodes are measured from OMI and then look for such patterns over other polluted regions of the globe. We gather individual high-quality O3 surface site measurements from these other regions, to check on our satellite detection. Our approach with global satellite detection would avoid issues associated with regional variations in seasonality, chemical regime, data product biases; and it does not require defining a separate absolute threshold for each data product (surface site and satellite). This also enables coherent linking of the extreme events into large-scale pollution episodes whose magnitude evolves over 100's of km for several days. Tools used here include the UC Irvine CTM, which shows that much of the O3 surface variability is lost at heights above 2 km, but AQX local events are readily seen in a 0-3 km column average. The OMI data are taken from X

Difficult Children

DEFF Research Database (Denmark)

Christensen, Else

. Especially on children and their development in social relations to children at the same age, on how the mothers experience their child and on the parent’s resources concerning health, education and job situation. The paper presents results from the first two data collections (1996 and 1999) in a prospective...... in contact with their peers, more attention-related problems and less emotional or psychological resources. Furthermore the mothers experience more trouble in child rearing than what is found in an average family. The results are important in the way that they attract attention to the child’s own situation...... the family in a poor position regarding the children’s well-being, health and development, but not so severe that the child is to be placed out of home. The paper concentrates attention on differences between families with and without contact to the social service department for reasons related to the child...

Statistics of Extremes

KAUST Repository

Davison, Anthony C.

2015-04-10

Statistics of extremes concerns inference for rare events. Often the events have never yet been observed, and their probabilities must therefore be estimated by extrapolation of tail models fitted to available data. Because data concerning the event of interest may be very limited, efficient methods of inference play an important role. This article reviews this domain, emphasizing current research topics. We first sketch the classical theory of extremes for maxima and threshold exceedances of stationary series. We then review multivariate theory, distinguishing asymptotic independence and dependence models, followed by a description of models for spatial and spatiotemporal extreme events. Finally, we discuss inference and describe two applications. Animations illustrate some of the main ideas. © 2015 by Annual Reviews. All rights reserved.

Students' perceptions of difficult concepts in biology in senior ...

African Journals Online (AJOL)

Students' perceptions of difficult concepts in biology in senior secondary schools in ... that students in Senior Secondary School Two (SSII) have difficulties in learning, the ... However, teaching strategies, students' attitude, inadequate learning ...

The difficult wind power

International Nuclear Information System (INIS)

Groenaas, Sigbjoern

2005-01-01

The article presents a brief survey of the conditions for wind power production in Norway and points out that several areas should be well suited. A comparison to Danish climate is made. The wind variations, turbulence problems and regional conditions are discussed

Moving in extreme environments: what's extreme and who decides?

Science.gov (United States)

Cotter, James David; Tipton, Michael J

2014-01-01

Humans work, rest and play in immensely varied extreme environments. The term 'extreme' typically refers to insufficiency or excess of one or more stressors, such as thermal energy or gravity. Individuals' behavioural and physiological capacity to endure and enjoy such environments varies immensely. Adverse effects of acute exposure to these environments are readily identifiable (e.g. heat stroke or bone fracture), whereas adverse effects of chronic exposure (e.g. stress fractures or osteoporosis) may be as important but much less discernable. Modern societies have increasingly sought to protect people from such stressors and, in that way, minimise their adverse effects. Regulations are thus established, and advice is provided on what is 'acceptable' exposure. Examples include work/rest cycles in the heat, hydration regimes, rates of ascent to and duration of stay at altitude and diving depth. While usually valuable and well intentioned, it is important to realise the breadth and importance of limitations associated with such guidelines. Regulations and advisories leave less room for self-determination, learning and perhaps adaptation. Regulations based on stress (e.g. work/rest cycles relative to WBGT) are more practical but less direct than those based on strain (e.g. core temperature), but even the latter can be substantively limited (e.g. by lack of criterion validation and allowance for behavioural regulation in the research on which they are based). Extreme Physiology & Medicine is publishing a series of reviews aimed at critically examining the issues involved with self- versus regulation-controlled human movement acutely and chronically in extreme environments. These papers, arising from a research symposium in 2013, are about the impact of people engaging in such environments and the effect of rules and guidelines on their safety, enjoyment, autonomy and productivity. The reviews will cover occupational heat stress, sporting heat stress, hydration, diving

All India Difficult Airway Association 2016 guidelines for the management of unanticipated difficult tracheal intubation in obstetrics

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Venkateswaran Ramkumar

2016-01-01

Full Text Available The various physiological changes in pregnancy make the parturient vulnerable for early and rapid desaturation. Severe hypoxaemia during intubation can potentially compromise two lives (mother and foetus. Thus tracheal intubation in the pregnant patient poses unique challenges, and necessitates meticulous planning, ready availability of equipment and expertise to ensure maternal and foetal safety. The All India Difficult Airway Association (AIDAA proposes a stepwise plan for the safe management of the airway in obstetric patients. These guidelines have been developed based on available evidence; wherever robust evidence was lacking, recommendations were arrived at by consensus opinion of airway experts, incorporating the responses to a questionnaire sent to members of the AIDAA and the Indian Society of Anaesthesiologists (ISA. Modified rapid sequence induction using gentle intermittent positive pressure ventilation with pressure limited to ≤20 cm H 2 O is acceptable. Partial or complete release of cricoid pressure is recommended when face mask ventilation, placement of supraglottic airway device (SAD or tracheal intubation prove difficult. One should call for early expert assistance. Maternal SpO 2 should be maintained ≥95%. Apnoeic oxygenation with nasal insufflation of 15 L/min oxygen during apnoea should be performed in all patients. If tracheal intubation fails, a second- generation SAD should be inserted. The decision to continue anaesthesia and surgery via the SAD, or perform fibreoptic-guided intubation via the SAD or wake up the patient depends on the urgency of surgery, foeto-maternal status and availability of resources and expertise. Emergency cricothyroidotomy must be performed if complete ventilation failure occurs.

Survey of extreme load design regulatory agency licensing requirements for nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Stevenson, J D

1976-04-01

Since 1965, when extreme load requirements began to be considered explicitly in nuclear power plant design, there has been a gradual divergence in requirements imposed by national regulatory agencies. However, nuclear plant safety is an international problem because of the potential international effects of any postulated plant failure. For this reason this paper has been prepared in an attempt to highlight the differences in national criteria currently used in the extreme load design of nuclear plant facilities. No attempt has been made to evaluate the relative merit of the criteria established by the various national regulatory agencies. This paper presents the results of a recent survey made of national atomic energy regulatory agencies and major nuclear steam supply design agencies, which requested a summary of current licensing criteria associated with earthquake, extreme wind (tornado), flood, airplane crash and accident (pipe break) loads applicable within the various national jurisdictions. Also presented are a number of comparisons which are meant to illustrate the differences in national regulatory criteria.

Survey of extreme load design regulatory agency licensing requirements for nuclear power plants

International Nuclear Information System (INIS)

Stevenson, J.D.

1976-01-01

Since 1965, when extreme load requirements began to be considered explicitly in nuclear power plant design, there has been a gradual divergence in requirements imposed by national regulatory agencies. However, nuclear plant safety is an international problem because of the potential international effects of any postulated plant failure. For this reason this paper has been prepared in an attempt to highlight the differences in national criteria currently used in the extreme load design of nuclear plant facilities. No attempt has been made to evaluate the relative merit of the criteria established by the various national regulatory agencies. This paper presents the results of a recent survey made of national atomic energy regulatory agencies and major nuclear steam supply design agencies, which requested a summary of current licensing criteria associated with earthquake, extreme wind (tornado), flood, airplane crash and accident (pipe break) loads applicable within the various national jurisdictions. Also presented are a number of comparisons which are meant to illustrate the differences in national regulatory criteria. (Auth.)

[Outlier cases in surgical disciplines. Micro-economic and macro-economic problems].

Science.gov (United States)

Tecklenburg, A; Liebeneiner, J; Schaefer, O

2009-09-01

Postoperative complications will always occur and the negative impact puts strain on patients, relatives and the attending physicians. The conversion to a remuneration system based on flat rates (diagnosis-related groups) presents additional economic problems for hospitals in some resource-intensive treatments. This particularly pertains to extremely cost-intensive cases in which costs succeed revenue by the factor of 2 and are often surgical procedures. Here the economic risk increases with the number of interventions performed. Despite improvements in the remuneration system this problem persists. An improved payment for these treatments is desirable. To achieve this it is necessary to systematically analyze the extremely cost-intensive cases by experts of different medical disciplines to create a data basis for a proposal of a cost-covering payment.

Spectral collocation for multiparameter eigenvalue problems arising from separable boundary value problems

Science.gov (United States)

Plestenjak, Bor; Gheorghiu, Călin I.; Hochstenbach, Michiel E.

2015-10-01

In numerous science and engineering applications a partial differential equation has to be solved on some fairly regular domain that allows the use of the method of separation of variables. In several orthogonal coordinate systems separation of variables applied to the Helmholtz, Laplace, or Schrödinger equation leads to a multiparameter eigenvalue problem (MEP); important cases include Mathieu's system, Lamé's system, and a system of spheroidal wave functions. Although multiparameter approaches are exploited occasionally to solve such equations numerically, MEPs remain less well known, and the variety of available numerical methods is not wide. The classical approach of discretizing the equations using standard finite differences leads to algebraic MEPs with large matrices, which are difficult to solve efficiently. The aim of this paper is to change this perspective. We show that by combining spectral collocation methods and new efficient numerical methods for algebraic MEPs it is possible to solve such problems both very efficiently and accurately. We improve on several previous results available in the literature, and also present a MATLAB toolbox for solving a wide range of problems.

Modified Inverse First Order Reliability Method (I-FORM) for Predicting Extreme Sea States.

Energy Technology Data Exchange (ETDEWEB)

Eckert-Gallup, Aubrey Celia; Sallaberry, Cedric Jean-Marie; Dallman, Ann Renee; Neary, Vincent Sinclair

2014-09-01

Environmental contours describing extreme sea states are generated as the input for numerical or physical model simulation s as a part of the stand ard current practice for designing marine structure s to survive extreme sea states. Such environmental contours are characterized by combinations of significant wave height ( ) and energy period ( ) values calculated for a given recurrence interval using a set of data based on hindcast simulations or buoy observations over a sufficient period of record. The use of the inverse first - order reliability method (IFORM) i s standard design practice for generating environmental contours. In this paper, the traditional appli cation of the IFORM to generating environmental contours representing extreme sea states is described in detail and its merits and drawbacks are assessed. The application of additional methods for analyzing sea state data including the use of principal component analysis (PCA) to create an uncorrelated representation of the data under consideration is proposed. A reexamination of the components of the IFORM application to the problem at hand including the use of new distribution fitting techniques are shown to contribute to the development of more accurate a nd reasonable representations of extreme sea states for use in survivability analysis for marine struc tures. Keywords: In verse FORM, Principal Component Analysis , Environmental Contours, Extreme Sea State Characteri zation, Wave Energy Converters

Press problem related to nuclear energy news reporting

International Nuclear Information System (INIS)

Arai, Mitsuo

2008-01-01

Since the event of Niigataken Chuetsu-oki Earthquake in 2007 and the subsequent press reports on damage of nuclear power station after it, a stance of media is being questioned. In order to clear this problem, basic organizational structure of the press related to nuclear energy news was analyzed. Local news department, social news department, science news department and economical news department involve in nuclear energy news the accordance with their own situations and concerns. This structure makes problem of nuclear energy news reporting complicated. Changing this system is required but very difficult. It is concluded that the press problem around nuclear energy news is strange. (author)

Recent Research Trends in Genetic Algorithm Based Flexible Job Shop Scheduling Problems

OpenAIRE

Amjad, Muhammad Kamal; Butt, Shahid Ikramullah; Kousar, Rubeena; Ahmad, Riaz; Agha, Mujtaba Hassan; Faping, Zhang; Anjum, Naveed; Asgher, Umer

2018-01-01

Flexible Job Shop Scheduling Problem (FJSSP) is an extension of the classical Job Shop Scheduling Problem (JSSP). The FJSSP is known to be NP-hard problem with regard to optimization and it is very difficult to find reasonably accurate solutions of the problem instances in a rational time. Extensive research has been carried out in this area especially over the span of the last 20 years in which the hybrid approaches involving Genetic Algorithm (GA) have gained the most popularity. Keeping in...

Dealing with the problem countries

International Nuclear Information System (INIS)

Jones, R.W.

1985-01-01

The test of America's policies to prevent nuclear proliferation is the so-called problem countries, those states that pose the greatest risk of ''going nuclear.'' Most visible - and the source of greatest concern - are those countries which have developed or appear to be in the process of developing nuclear weapons capabilities. In addition to Pakistan, near-nuclear countries of note include India, Israel, South Africa, Argentina, South Korea, and Taiwan. Several other countries, including Iraq, Iran, Libya, and Brazil, seem to pose proliferation risks in the longer term. More problematic are countries, such as Mexico, that, although they seem to represent little or no proliferation risk themselves, pose difficult problems by challenging restrictions in nuclear export policy. The author examines US policy toward some of the problem countries, paying particular attention to Pakistan. The constants in US policy and the few changes wrought by the Reagan administration are noted throughout

Noticing relevant problem features: activating prior knowledge affects problem solving by guiding encoding

Science.gov (United States)

Crooks, Noelle M.; Alibali, Martha W.

2013-01-01

This study investigated whether activating elements of prior knowledge can influence how problem solvers encode and solve simple mathematical equivalence problems (e.g., 3 + 4 + 5 = 3 + __). Past work has shown that such problems are difficult for elementary school students (McNeil and Alibali, 2000). One possible reason is that children's experiences in math classes may encourage them to think about equations in ways that are ultimately detrimental. Specifically, children learn a set of patterns that are potentially problematic (McNeil and Alibali, 2005a): the perceptual pattern that all equations follow an “operations = answer” format, the conceptual pattern that the equal sign means “calculate the total”, and the procedural pattern that the correct way to solve an equation is to perform all of the given operations on all of the given numbers. Upon viewing an equivalence problem, knowledge of these patterns may be reactivated, leading to incorrect problem solving. We hypothesized that these patterns may negatively affect problem solving by influencing what people encode about a problem. To test this hypothesis in children would require strengthening their misconceptions, and this could be detrimental to their mathematical development. Therefore, we tested this hypothesis in undergraduate participants. Participants completed either control tasks or tasks that activated their knowledge of the three patterns, and were then asked to reconstruct and solve a set of equivalence problems. Participants in the knowledge activation condition encoded the problems less well than control participants. They also made more errors in solving the problems, and their errors resembled the errors children make when solving equivalence problems. Moreover, encoding performance mediated the effect of knowledge activation on equivalence problem solving. Thus, one way in which experience may affect equivalence problem solving is by influencing what students encode about the

Social Problems in Canadian Ice Hockey: An Exploration Through Film

Directory of Open Access Journals (Sweden)

Fogel Curtis A.

2014-12-01

Full Text Available While celebrated as a highly popular sport in Canada, there are many social problems existing within and around Canadian ice hockey. These problems are often overlooked and rarely depicted in academic and journalistic research on sport. These social problems include, but are not limited to: extreme violence resulting in injuries and death, hazing rituals, multiple types of sexual violence, drug abuse, financial corruption, as well as various forms of prejudice and discrimination. Prompted by pop-cultural depictions in films, this paper further identifies and explores social problems in Canadian ice hockey revealing the realism embedded within various seemingly fictional films.

Efficient authentication scheme based on near-ring root extraction problem

Science.gov (United States)

Muthukumaran, V.; Ezhilmaran, D.

2017-11-01

An authentication protocolis the type of computer communication protocol or cryptography protocol specifically designed for transfer of authentication data between two entities. We have planned a two new entity authentication scheme on the basis of root extraction problem near-ring in this article. We suggest that this problem is suitably difficult to serve as a cryptographic assumption over the platform of near-ring N. The security issues also discussed.

A Comparison of Approaches for Solving Hard Graph-Theoretic Problems

Science.gov (United States)

2015-04-29

and Search”, in Discrete Mathematics and Its Applications, Book 7, CRC Press (1998): Boca Raton. [6] A. Lucas, “Ising Formulations of Many NP Problems...owner. 14. ABSTRACT In order to formulate mathematical conjectures likely to be true, a number of base cases must be determined. However, many... combinatorial problems are NP-hard and the computational complexity makes this research approach difficult using a standard brute force approach on a

Difficult airway management patterns among anesthesiologists practicing in Cairo University Hospitals

Directory of Open Access Journals (Sweden)

Neamat I. Abdel rahman

2016-01-01

Conclusion: The practice of anesthesiologists in Cairo university hospitals is close to the recommendations of the ASA guidelines for management of difficult airway. There is increased skills in fiberoptic bronchoscopes and SGA with increased frequency of difficult airway managements training courses; however, they need to improve their skills in awake fiberoptic intubations technique and they need to be trained on invasive airway management access to close the discrepancy between their theoretical choices in different situations and their actual skills.

Variable effects of climate on forest growth in relation to climate extremes, disturbance, and forest dynamics.

Science.gov (United States)

Itter, Malcolm S; Finley, Andrew O; D'Amato, Anthony W; Foster, Jane R; Bradford, John B

2017-06-01

Changes in the frequency, duration, and severity of climate extremes are forecast to occur under global climate change. The impacts of climate extremes on forest productivity and health remain difficult to predict due to potential interactions with disturbance events and forest dynamics-changes in forest stand composition, density, size and age structure over time. Such interactions may lead to non-linear forest growth responses to climate involving thresholds and lag effects. Understanding how forest dynamics influence growth responses to climate is particularly important given stand structure and composition can be modified through management to increase forest resistance and resilience to climate change. To inform such adaptive management, we develop a hierarchical Bayesian state space model in which climate effects on tree growth are allowed to vary over time and in relation to past climate extremes, disturbance events, and forest dynamics. The model is an important step toward integrating disturbance and forest dynamics into predictions of forest growth responses to climate extremes. We apply the model to a dendrochronology data set from forest stands of varying composition, structure, and development stage in northeastern Minnesota that have experienced extreme climate years and forest tent caterpillar defoliation events. Mean forest growth was most sensitive to water balance variables representing climatic water deficit. Forest growth responses to water deficit were partitioned into responses driven by climatic threshold exceedances and interactions with insect defoliation. Forest growth was both resistant and resilient to climate extremes with the majority of forest growth responses occurring after multiple climatic threshold exceedances across seasons and years. Interactions between climate and disturbance were observed in a subset of years with insect defoliation increasing forest growth sensitivity to water availability. Forest growth was particularly

Variable effects of climate on forest growth in relation to climate extremes, disturbance, and forest dynamics

Science.gov (United States)

Itter, Malcolm S.; Finley, Andrew O.; D'Amato, Anthony W.; Foster, Jane R.; Bradford, John B.

2017-01-01

Changes in the frequency, duration, and severity of climate extremes are forecast to occur under global climate change. The impacts of climate extremes on forest productivity and health remain difficult to predict due to potential interactions with disturbance events and forest dynamics—changes in forest stand composition, density, size and age structure over time. Such interactions may lead to non-linear forest growth responses to climate involving thresholds and lag effects. Understanding how forest dynamics influence growth responses to climate is particularly important given stand structure and composition can be modified through management to increase forest resistance and resilience to climate change. To inform such adaptive management, we develop a hierarchical Bayesian state space model in which climate effects on tree growth are allowed to vary over time and in relation to past climate extremes, disturbance events, and forest dynamics. The model is an important step toward integrating disturbance and forest dynamics into predictions of forest growth responses to climate extremes. We apply the model to a dendrochronology data set from forest stands of varying composition, structure, and development stage in northeastern Minnesota that have experienced extreme climate years and forest tent caterpillar defoliation events. Mean forest growth was most sensitive to water balance variables representing climatic water deficit. Forest growth responses to water deficit were partitioned into responses driven by climatic threshold exceedances and interactions with insect defoliation. Forest growth was both resistant and resilient to climate extremes with the majority of forest growth responses occurring after multiple climatic threshold exceedances across seasons and years. Interactions between climate and disturbance were observed in a subset of years with insect defoliation increasing forest growth sensitivity to water availability. Forest growth was particularly

Invited Article: Visualisation of extreme value events in optical communications

Science.gov (United States)

Derevyanko, Stanislav; Redyuk, Alexey; Vergeles, Sergey; Turitsyn, Sergei

2018-06-01

Fluctuations of a temporal signal propagating along long-haul transoceanic scale fiber links can be visualised in the spatio-temporal domain drawing visual analogy with ocean waves. Substantial overlapping of information symbols or use of multi-frequency signals leads to strong statistical deviations of local peak power from an average signal power level. We consider long-haul optical communication systems from this unusual angle, treating them as physical systems with a huge number of random statistical events, including extreme value fluctuations that potentially might affect the quality of data transmission. We apply the well-established concepts of adaptive wavefront shaping used in imaging through turbid medium to detect the detrimental phase modulated sequences in optical communications that can cause extreme power outages (rare optical waves of ultra-high amplitude) during propagation down the ultra-long fiber line. We illustrate the concept by a theoretical analysis of rare events of high-intensity fluctuations—optical freak waves, taking as an example an increasingly popular optical frequency division multiplexing data format where the problem of high peak to average power ratio is the most acute. We also show how such short living extreme value spikes in the optical data streams are affected by nonlinearity and demonstrate the negative impact of such events on the system performance.

What if solar energy becomes really cheap? A thought experiment on environmental problem shifting

NARCIS (Netherlands)

Bergh, Van den Jeroen; Folke, Carl; Polasky, Stephen; Scheffer, Marten; Steffen, Will

2015-01-01

Solving one environmental problem may often invoke or intensify another one. Such environmental problem shifting (EPS) is a neglected topic in global sustainability research. Indeed, it is difficult to study as it requires the merging of insights from various research areas. Here we identify

What if solar energy becomes really cheap? A thought experiment on environmental problem shifting

NARCIS (Netherlands)

van den Bergh, J.C.J.M.; Folke, C.; Polasky, S.; Scheffer, M.; Steffen, W.

2015-01-01

Solving one environmental problem may often invoke or intensify another one. Such environmental problem shifting (EPS) is a neglected topic in global sustainability research. Indeed, it is difficult to study as it requires the merging of insights from various research areas. Here we identify

A Modified Alternating Direction Method for Variational Inequality Problems

International Nuclear Information System (INIS)

Han, D.

2002-01-01

The alternating direction method is an attractive method for solving large-scale variational inequality problems whenever the subproblems can be solved efficiently. However, the subproblems are still variational inequality problems, which are as structurally difficult to solve as the original one. To overcome this disadvantage, in this paper we propose a new alternating direction method for solving a class of nonlinear monotone variational inequality problems. In each iteration the method just makes an orthogonal projection to a simple set and some function evaluations. We report some preliminary computational results to illustrate the efficiency of the method

An efficient and accurate solution methodology for bilevel multi-objective programming problems using a hybrid evolutionary-local-search algorithm.

Science.gov (United States)

Deb, Kalyanmoy; Sinha, Ankur

2010-01-01

Bilevel optimization problems involve two optimization tasks (upper and lower level), in which every feasible upper level solution must correspond to an optimal solution to a lower level optimization problem. These problems commonly appear in many practical problem solving tasks including optimal control, process optimization, game-playing strategy developments, transportation problems, and others. However, they are commonly converted into a single level optimization problem by using an approximate solution procedure to replace the lower level optimization task. Although there exist a number of theoretical, numerical, and evolutionary optimization studies involving single-objective bilevel programming problems, not many studies look at the context of multiple conflicting objectives in each level of a bilevel programming problem. In this paper, we address certain intricate issues related to solving multi-objective bilevel programming problems, present challenging test problems, and propose a viable and hybrid evolutionary-cum-local-search based algorithm as a solution methodology. The hybrid approach performs better than a number of existing methodologies and scales well up to 40-variable difficult test problems used in this study. The population sizing and termination criteria are made self-adaptive, so that no additional parameters need to be supplied by the user. The study indicates a clear niche of evolutionary algorithms in solving such difficult problems of practical importance compared to their usual solution by a computationally expensive nested procedure. The study opens up many issues related to multi-objective bilevel programming and hopefully this study will motivate EMO and other researchers to pay more attention to this important and difficult problem solving activity.

Myth 15: High-Ability Students Don't Face Problems and Challenges

Science.gov (United States)

Moon, Sidney M.

2009-01-01

One rationale for failure to address the needs of high-ability students in schools is that high-ability students do not need special services because they do not face any special problems or challenges. A more extreme corollary of this attitude is the notion that high ability is so protective that students with high ability do not face problems or…

Student Homicidal Violence in Schools: An International Problem

Science.gov (United States)

Bondu, Rebecca; Cornell, Dewey G.; Scheithauer, Herbert

2011-01-01

School homicides have become a worldwide phenomenon. In the decade following the Columbine shooting there have been at least forty similar events in other countries. This article addresses the international scope of this problem and some of the complex conceptual issues that make student homicidal violence difficult to define and study. Meaningful…

A Large-Scale Multi-Hop Localization Algorithm Based on Regularized Extreme Learning for Wireless Networks.

Science.gov (United States)

Zheng, Wei; Yan, Xiaoyong; Zhao, Wei; Qian, Chengshan

2017-12-20

A novel large-scale multi-hop localization algorithm based on regularized extreme learning is proposed in this paper. The large-scale multi-hop localization problem is formulated as a learning problem. Unlike other similar localization algorithms, the proposed algorithm overcomes the shortcoming of the traditional algorithms which are only applicable to an isotropic network, therefore has a strong adaptability to the complex deployment environment. The proposed algorithm is composed of three stages: data acquisition, modeling and location estimation. In data acquisition stage, the training information between nodes of the given network is collected. In modeling stage, the model among the hop-counts and the physical distances between nodes is constructed using regularized extreme learning. In location estimation stage, each node finds its specific location in a distributed manner. Theoretical analysis and several experiments show that the proposed algorithm can adapt to the different topological environments with low computational cost. Furthermore, high accuracy can be achieved by this method without setting complex parameters.

Consideration of Task Performance for Robots Engaged in Extremely Dangerous Environment in Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Hong, Seung Mo; Han, Kee Soo; Yi, Sung Deok; Kim, Seoung Rae [Nuclear Engineering Service and Solution Co. Ltd., Daejeon (Korea, Republic of); Choi, Young [KAERI, Daejeon (Korea, Republic of)

2015-05-15

After Fukushima Daiichi Nuclear Accident, it is started to pay more attention to operation and accident of nuclear power plants (NPPs). For domestic nuclear industry, it was recommended to establish corresponding strategies against accidents due to extremely dangerous natural disasters. Each nuclear power plant is also preparing to establish strategies to secure nuclear safety functions by estimating the counterplans for extreme accidents. Robots are particularly being used to access the areas where those are dangerous for human beings to access or to restore the accident. Robot technologies in NPPs are emerging cutting-edge technologies that are just a start except the developed countries like USA, Japan, etc. But they are carefully considered because they have the advantages of performing tasks in extremely dangerous environment in NPPs instead of human beings. In this study, the applicability of robots will be considered in extremely dangerous environment in NPPs. Accurate judgment of the inside situation of the plant and quick actions in the extreme condition like earthquake accompanied by loss of all AC powers should be considered as major function in terms of prevention of accident spread. According to the reported stress test results of domestic NPPs, the difficult things for operators to carry out in extreme conditions can be predictable, therefore the active use of robots as accident mitigation strategies will be helpful to reduce the unnecessary spending for facility improvement. Current trend of domestic and foreign robot technology development focuses on the information search of the inside of the plant and development of preventive maintenance of NPPs. As seen actually in Fukushima Daiichi, main roles of robots place emphasis on measuring the inside radiation level accessing to the area where operator cannot access and delivering information which can support operator's decision-making and actions. Therefore, it is considered that development of

Distractor dwelling, skipping, and revisiting determine target absent performance in difficult visual search

Directory of Open Access Journals (Sweden)

Gernot Horstmann

2016-08-01

Full Text Available Some targets in visual search are more difficult to find than others. In particular, a target that is similar to the distractors is more difficult to find than a target that is dissimilar to the distractors. Efficiency differences between easy and difficult searches are manifest not only in target-present trials but also in target-absent trials. In fact, even physically identical displays are searched through with different efficiency depending on the searched-for target. Here, we monitored eye movements in search for a target similar to the distractors (difficult search versus a target dissimilar to the distractors (easy search. We aimed to examine three hypotheses concerning the causes of differential search efficiencies in target-absent trials: (a distractor dwelling (b distractor skipping, and (c distractor revisiting. Reaction times increased with target similarity which is consistent with existing theories and replicates earlier results. Eye movement data indicated guidance in target trials, even though search was very slow. Dwelling, skipping, and revisiting contributed to low search efficiency in difficult search, with dwelling being the strongest factor. It is argued that differences in dwell time account for a large amount of total search time differences.

Distractor Dwelling, Skipping, and Revisiting Determine Target Absent Performance in Difficult Visual Search

Science.gov (United States)

Horstmann, Gernot; Herwig, Arvid; Becker, Stefanie I.

2016-01-01

Some targets in visual search are more difficult to find than others. In particular, a target that is similar to the distractors is more difficult to find than a target that is dissimilar to the distractors. Efficiency differences between easy and difficult searches are manifest not only in target-present trials but also in target-absent trials. In fact, even physically identical displays are searched through with different efficiency depending on the searched-for target. Here, we monitored eye movements in search for a target similar to the distractors (difficult search) versus a target dissimilar to the distractors (easy search). We aimed to examine three hypotheses concerning the causes of differential search efficiencies in target-absent trials: (a) distractor dwelling (b) distractor skipping, and (c) distractor revisiting. Reaction times increased with target similarity which is consistent with existing theories and replicates earlier results. Eye movement data indicated guidance in target trials, even though search was very slow. Dwelling, skipping, and revisiting contributed to low search efficiency in difficult search, with dwelling being the strongest factor. It is argued that differences in dwell time account for a large amount of total search time differences. PMID:27574510

Low-cost approaches to problem-driven hydrologic research: The case of Arkavathy watershed, India.

Science.gov (United States)

Srinivasan, V.; Ballukraya, P. N.; Jeremiah, K.; R, A.

2014-12-01

Groundwater depletion is a major problem in the Arkavathy Basin and it is the probable cause of declining flows in the Arkavathy River. However, investigating groundwater trends and groundwater-surface water linkages is extremely challenging in a data-scarce environment where basins are largely ungauged so there is very little historical data; often the data are missing, flawed or biased. Moreover, hard-rock aquifer data are very difficult to interpret. In the absence of reliable data, establishing a trend let alone the causal linkages is a severe challenge. We used a combination of low-cost, participatory, satellite based and conventional data collection methods to maximize spatial and temporal coverage of data. For instance, long-term groundwater trends are biased because only a few dug wells with non-representative geological conditions still have water - the vast majority of the monitoring wells drilled in the 1970s and 1980s have dried up. Instead, we relied on "barefoot hydrology" techniques. By conducting a comprehensive well census, engaging farmers in participatory groundwater monitoring and using locally available commercial borewell scanning techniques we have been able to better establish groundwater trends and spatial patterns.

An Assessment of the Effect of Collaborative Groups on Students' Problem-Solving Strategies and Abilities

Science.gov (United States)

Cooper, Melanie M.; Cox, Charles T., Jr.; Nammouz, Minory; Case, Edward; Stevens, Ronald

2008-01-01

Improving students' problem-solving skills is a major goal for most science educators. While a large body of research on problem solving exists, assessment of meaningful problem solving is very difficult, particularly for courses with large numbers of students in which one-on-one interactions are not feasible. We have used a suite of software…

Likelihood estimators for multivariate extremes

KAUST Repository

Huser, Raphaë l; Davison, Anthony C.; Genton, Marc G.

2015-01-01

The main approach to inference for multivariate extremes consists in approximating the joint upper tail of the observations by a parametric family arising in the limit for extreme events. The latter may be expressed in terms of componentwise maxima, high threshold exceedances or point processes, yielding different but related asymptotic characterizations and estimators. The present paper clarifies the connections between the main likelihood estimators, and assesses their practical performance. We investigate their ability to estimate the extremal dependence structure and to predict future extremes, using exact calculations and simulation, in the case of the logistic model.

Likelihood estimators for multivariate extremes

KAUST Repository

Huser, Raphaël

2015-11-17

The main approach to inference for multivariate extremes consists in approximating the joint upper tail of the observations by a parametric family arising in the limit for extreme events. The latter may be expressed in terms of componentwise maxima, high threshold exceedances or point processes, yielding different but related asymptotic characterizations and estimators. The present paper clarifies the connections between the main likelihood estimators, and assesses their practical performance. We investigate their ability to estimate the extremal dependence structure and to predict future extremes, using exact calculations and simulation, in the case of the logistic model.

Characteristics of Extreme Extratropical Cyclones in a High-Resolution Global Climate Model

Science.gov (United States)

Catalano, A. J.; Broccoli, A. J.; Kapnick, S. B.; Janoski, T. P.

2017-12-01

In the northeastern United States, many of the strongest impacts from extratropical cyclones (ETCs) are associated with storms that exhibit slow movement, unusual tracks, or exceptional intensity. Examples of extreme ETCs include the Appalachian storm of November 1950, the Perfect Storm of October 1991, and the Superstorm of March 1993. Owing to the rare nature of these events, it is difficult to quantify the associated risks (e.g. high winds, storm surge) given the limited duration of high-quality observational datasets. Furthermore, storms with even greater impacts than those observed may be possible, particularly in a warming climate. In the context of tropical cyclones, Lin and Emanuel (2016) have used the metaphor "grey swans" to refer to high-impact events that have not been observed but may be physically possible. One method for analyzing "grey swans" is to generate a larger sample of ETCs using a coupled climate model. Therefore, we use long simulations (over 1,000 years with atmospheric constituents fixed at 1990 levels) from a global climate model (GFDL FLOR) with 50km atmospheric resolution. FLOR has been shown to realistically simulate the spatial distribution and climatology of ETCs during the reanalysis era. We will discuss the climatological features of these extreme ETC events.

Working in a difficult regime

International Nuclear Information System (INIS)

Pesic, M.; Cupac, S.

1996-01-01

RA and RB, the two research reactors at the Vinca Institute of Nuclear sciences were built in the late 1950s. Both were designed according to the national (former Yugoslavia) plan for developing nuclear energy. Although some modifications have been successfully made, they are now suffering from problems of ageing and funding since the attitude to the country's nuclear program has changed. Some of the equipment is fit for a museum. But the problem of ageing components is only one of the difficulties faced by the operators, they also cope with the political and financial conditions prevailing in the country

Mapped Fourier Methods for stiff problems in toroidal geometry

OpenAIRE

Guillard , Herve

2014-01-01

Fourier spectral or pseudo-spectral methods are usually extremely efficient for periodic problems. However this efficiency is lost if the solutions have zones of rapid variations or internal layers. For these cases, a large number of Fourier modes are required and this makes the Fourier method unpractical in many cases. This work investigates the use of mapped Fourier method as a way to circumvent this problem. Mapped Fourier method uses instead of the usual Fourier interpolant the compositio...

Self-teaching neural network learns difficult reactor control problem

International Nuclear Information System (INIS)

Jouse, W.C.

1989-01-01

A self-teaching neural network used as an adaptive controller quickly learns to control an unstable reactor configuration. The network models the behavior of a human operator. It is trained by allowing it to operate the reactivity control impulsively. It is punished whenever either the power or fuel temperature stray outside technical limits. Using a simple paradigm, the network constructs an internal representation of the punishment and of the reactor system. The reactor is constrained to small power orbits

Bluefin tuna fishing and ranching: a difficult management problem

NARCIS (Netherlands)

Stefano, de V.; Heijden, van der P.G.M.

2007-01-01

The fish processing industry and consumers in Japan are willing to pay high (and sometimes outrageous) prices for fresh bluefin tuna with fat content and flesh colour just right to be served raw as sashimi or sushi. This willingness was and still is the economic incentive for a high fishing pressure

Classifying Returns as Extreme

DEFF Research Database (Denmark)

Christiansen, Charlotte

2014-01-01

I consider extreme returns for the stock and bond markets of 14 EU countries using two classification schemes: One, the univariate classification scheme from the previous literature that classifies extreme returns for each market separately, and two, a novel multivariate classification scheme tha...

A Social Network Approach to Provisioning and Management of Cloud Computing Services for Enterprises

DEFF Research Database (Denmark)

Kuada, Eric

been extremely difficult in the past; but with the advent of cloud computing, this problem should be less difficult to solve. Opportunistic Cloud Services (OCS) is about enterprises leveraging cloud computing technologies to contribute spare IT resources to a platform so that others on the platform can...... utilize them as and when needed. The OCS network is modelled as a social network of enterprises collaborating strategically in contributing and utilizing cloud services without entering into any business agreements. Such a platform faces several problems. One of such problems is the free riding problem...... challenges that were discovered during this study, the obtained results demonstrate both the technical feasibility and the existence of enabling conditions for the implementation of opportunistic cloud services for enterprises....

Some human-related problems in radiation protection

International Nuclear Information System (INIS)

Yoshizawa, Yasuo

1980-01-01

Radiation protection includes both human and source-related problems. The human problems have not only medical but also social aspects, such as labor management. Special attention should be paid to the fact that the subject of radiation protection is not a human being as living thing but as member of society. ICRP recommended that conditions of work can be divided into two classed, working condition A and B, according to annual exposure. This application is of great value to radiation protection practice. Nevertheless the legal regulations do not adopt it yet. The present condition of the medical surveillance of radiation workers is not appropriate from the scientific standpoint. This is the difficult problem which is caused by the delay of the legal application of ICRP recommendation. Compensation for occupational radiation hazards should be overlooked. This problem have been investigated by an authorized committee, but a number of unsolved problems still remain. (author)

Moisture-driven fracture in solid wood

DEFF Research Database (Denmark)

Larsen, Finn; Ormarsson, Sigurdur; Olesen, John Forbes

2011-01-01

Moisture-induced fractures in solid timber create considerable problems for both building industries and sawmills. Cracks caused by kiln-drying of solid timber are extremely difficult to predict. This paper reports on experiments concerned with methods of reducing cracks in wood and with the crac......Moisture-induced fractures in solid timber create considerable problems for both building industries and sawmills. Cracks caused by kiln-drying of solid timber are extremely difficult to predict. This paper reports on experiments concerned with methods of reducing cracks in wood...... process, suggesting that sealing the ends of timber logs while in the green moisture state could considerably reduce the development of end-cracks. The initial moisture content and the shrinkage properties of the wood varied markedly from pith to bark. The importance of taking material inhomogeneities...... into account when modelling crack propagation in solid wood is emphasized. © 2011 Taylor & Francis....

Transactional relations between caregiving stress, executive functioning, and problem behavior from early childhood to early adolescence

Science.gov (United States)

LaGasse, Linda L.; Conradt, Elisabeth; Karalunas, Sarah L.; Dansereau, Lynne M.; Butner, Jonathan E.; Shankaran, Seetha; Bada, Henrietta; Bauer, Charles R.; Whitaker, Toni M.; Lester, Barry M.

2016-01-01

Developmental psychopathologists face the difficult task of identifying the environmental conditions that may contribute to early childhood behavior problems. Highly stressed caregivers can exacerbate behavior problems, while children with behavior problems may make parenting more difficult and increase caregiver stress. Unknown is: (1) how these transactions originate, (2) whether they persist over time to contribute to the development of problem behavior and (3) what role resilience factors, such as child executive functioning, may play in mitigating the development of problem behavior. In the present study, transactional relations between caregiving stress, executive functioning, and behavior problems were examined in a sample of 1,388 children with prenatal drug exposures at three developmental time points: early childhood (birth-age 5), middle childhood (ages 6 to 9), and early adolescence (ages 10 to 13). Transactional relations differed between caregiving stress and internalizing versus externalizing behavior. Targeting executive functioning in evidence-based interventions for children with prenatal substance exposure who present with internalizing problems and treating caregiving psychopathology, depression, and parenting stress in early childhood may be particularly important for children presenting with internalizing behavior. PMID:27427803

Quantitative Sensory Testing and Current Perception Threshold Testing in Patients With Chronic Pain Following Lower Extremity Fracture.

Science.gov (United States)

Griffioen, Mari A; Greenspan, Joel D; Johantgen, Meg; Von Rueden, Kathryn; O'Toole, Robert V; Dorsey, Susan G; Renn, Cynthia L

2018-01-01

Chronic pain is a significant problem for patients with lower extremity injuries. While pain hypersensitivity has been identified in many chronic pain conditions, it is not known whether patients with chronic pain following lower extremity fracture report pain hypersensitivity in the injured leg. To quantify and compare peripheral somatosensory function and sensory nerve activation thresholds in persons with chronic pain following lower extremity fractures with a cohort of persons with no history of lower extremity fractures. This was a cross-sectional study where quantitative sensory testing and current perception threshold testing were conducted on the injured and noninjured legs of cases and both legs of controls. A total of 14 cases and 28 controls participated in the study. Mean time since injury at the time of testing for cases was 22.3 (standard deviation = 12.1) months. The warmth detection threshold ( p = .024) and nerve activation thresholds at 2,000 Hz ( p sensory nerve function at the site of injury in patients with chronic pain following lower extremity fractures using quantitative sensory testing and current perception threshold testing.

Probabilistic analysis of extreme wind events

Energy Technology Data Exchange (ETDEWEB)

Chaviaropoulos, P.K. [Center for Renewable Energy Sources (CRES), Pikermi Attikis (Greece)

1997-12-31

A vital task in wind engineering and meterology is to understand, measure, analyse and forecast extreme wind conditions, due to their significant effects on human activities and installations like buildings, bridges or wind turbines. The latest version of the IEC standard (1996) pays particular attention to the extreme wind events that have to be taken into account when designing or certifying a wind generator. Actually, the extreme wind events within a 50 year period are those which determine the ``static`` design of most of the wind turbine components. The extremes which are important for the safety of wind generators are those associated with the so-called ``survival wind speed``, the extreme operating gusts and the extreme wind direction changes. A probabilistic approach for the analysis of these events is proposed in this paper. Emphasis is put on establishing the relation between extreme values and physically meaningful ``site calibration`` parameters, like probability distribution of the annual wind speed, turbulence intensity and power spectra properties. (Author)

EMA beamline at SIRIUS: extreme condition X-ray methods of analysis

International Nuclear Information System (INIS)

Souza Neto, Narcizo

2016-01-01

Full text: The EMA beamline (Extreme condition X-ray Methods of Analysis) is one of the hard x-ray undulator beamlines within the first phase of the new synchrotron source in Brazil (Sirius project). This beamline is thought to make a difference where a high brilliance (high flux of up to 2 x 10 14 photons/sec with beam size down to 0.5 x 0.5 μm 2 ) is essential, which is the case for extreme pressures that require small focus and time-resolved that require high photon flux. With that in mind we propose the beamline to have two experimental hutches to cover most of the extreme condition techniques today employed at synchrotron laboratories worldwide. These two stations are thought to provide the general infrastructure for magnets and lasers experiments, which may evolve as new scientific problems appear. In addition to the hutches, support laboratories will be strongly linked and supportive to the experiments at the beamline, covering high pressure instrumentations using diamond anvil cells and pump-and-probe requirements for ultrafast and high power lasers. Along these lines, we will describe the following techniques covered at this beamline: magnetic spectroscopy (XMCD) and scattering (XRMS) under high pressure and very low temperature in order to fully probe both ferromagnetic and antiferromagnetic materials and the dependence with pressure; extreme pressure and temperature XRD and XAS experiments using very small diamond culet anvils and high power lasers. (author)

EMA beamline at SIRIUS: extreme condition X-ray methods of analysis

Energy Technology Data Exchange (ETDEWEB)

Souza Neto, Narcizo, E-mail: narcizo.souza@lnls.br [Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP (Brazil)

2016-07-01

Full text: The EMA beamline (Extreme condition X-ray Methods of Analysis) is one of the hard x-ray undulator beamlines within the first phase of the new synchrotron source in Brazil (Sirius project). This beamline is thought to make a difference where a high brilliance (high flux of up to 2 x 10{sup 14} photons/sec with beam size down to 0.5 x 0.5 μm{sup 2}) is essential, which is the case for extreme pressures that require small focus and time-resolved that require high photon flux. With that in mind we propose the beamline to have two experimental hutches to cover most of the extreme condition techniques today employed at synchrotron laboratories worldwide. These two stations are thought to provide the general infrastructure for magnets and lasers experiments, which may evolve as new scientific problems appear. In addition to the hutches, support laboratories will be strongly linked and supportive to the experiments at the beamline, covering high pressure instrumentations using diamond anvil cells and pump-and-probe requirements for ultrafast and high power lasers. Along these lines, we will describe the following techniques covered at this beamline: magnetic spectroscopy (XMCD) and scattering (XRMS) under high pressure and very low temperature in order to fully probe both ferromagnetic and antiferromagnetic materials and the dependence with pressure; extreme pressure and temperature XRD and XAS experiments using very small diamond culet anvils and high power lasers. (author)

MAIN PROBLEMS OF MOULDING OF SILUMINS. WAYS OF SOLUTION

Directory of Open Access Journals (Sweden)

E. I. Marukovich

2016-01-01

Full Text Available The main problems of silumin’ moulding are connected with insufficient modifying of casting structure, their considerable inclination to gas porosity, difficult to remove nonmetallic inclusions and these features are shown in the article. Protection of liquid silumin from influence of the air atmosphere; use of crucibles from aluminum oxide; refinement of fusion from nonmetallic inclusions and application of the accelerated hydrogen hardening of castings were used to solve these problems, as it is shown in the article.

Management and outcome of extremely low birth weight infants

Directory of Open Access Journals (Sweden)

Apostolos Papageorgiou

2014-06-01

Full Text Available Survival of extremely low birth weight (ELBW and extremely premature (EP infants has shown consistent improvement thanks to advances and innovations in perinatal and neonatal care. Regionalization, with high-risk deliveries in a tertiary perinatal center, offers the coordinated, collaborative, expert and specialized care needed by these mothers and their infants. Despite decreasing rates of the major neonatal morbidities observed in recent years, these continue still to be significant for ELBW/EP infants, impacting their overall prognosis. After NICU discharge and in the first years of life, issues with health, growth and development are common. In school age and adolescence, problems with behavior, socialization and cognition are prevalent. Adult outcomes of ELBW/EP need further clarity, emphasizing the importance for consistent long-term follow-up for this special cohort. Proceedings of the 10th International Workshop on Neonatology · Cagliari (Italy · October 22nd-25th, 2014 · The last ten years, the next ten years in Neonatology Guest Editors: Vassilios Fanos, Michele Mussap, Gavino Faa, Apostolos Papageorgiou

The Relationship between Spatial and Temporal Magnitude Estimation of Scientific Concepts at Extreme Scales

Science.gov (United States)

Price, Aaron; Lee, H.

2010-01-01

Many astronomical objects, processes, and events exist and occur at extreme scales of spatial and temporal magnitudes. Our research draws upon the psychological literature, replete with evidence of linguistic and metaphorical links between the spatial and temporal domains, to compare how students estimate spatial and temporal magnitudes associated with objects and processes typically taught in science class.. We administered spatial and temporal scale estimation tests, with many astronomical items, to 417 students enrolled in 12 undergraduate science courses. Results show that while the temporal test was more difficult, students’ overall performance patterns between the two tests were mostly similar. However, asymmetrical correlations between the two tests indicate that students think of the extreme ranges of spatial and temporal scales in different ways, which is likely influenced by their classroom experience. When making incorrect estimations, students tended to underestimate the difference between the everyday scale and the extreme scales on both tests. This suggests the use of a common logarithmic mental number line for both spatial and temporal magnitude estimation. However, there are differences between the two tests in the errors student make in the everyday range. Among the implications discussed is the use of spatio-temporal reference frames, instead of smooth bootstrapping, to help students maneuver between scales of magnitude and the use of logarithmic transformations between reference frames. Implications for astronomy range from learning about spectra to large scale galaxy structure.

Stationary and non-stationary extreme value modeling of extreme temperature in Malaysia

Science.gov (United States)

Hasan, Husna; Salleh, Nur Hanim Mohd; Kassim, Suraiya

2014-09-01

Extreme annual temperature of eighteen stations in Malaysia is fitted to the Generalized Extreme Value distribution. Stationary and non-stationary models with trend are considered for each station and the Likelihood Ratio test is used to determine the best-fitting model. Results show that three out of eighteen stations i.e. Bayan Lepas, Labuan and Subang favor a model which is linear in the location parameter. A hierarchical cluster analysis is employed to investigate the existence of similar behavior among the stations. Three distinct clusters are found in which one of them consists of the stations that favor the non-stationary model. T-year estimated return levels of the extreme temperature are provided based on the chosen models.

Difficult factors in Management of Impacted Dental Prosthesis in Esophagus

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Efiaty A. Soepardi

2005-03-01

Full Text Available A dental prosthesis which ingested and impacted in esophagus, is an emergency case and life threatening, so require immediate esophagoscopy intervention for removing. The objective of this study is to assess some factors can caused dtfficulties in diagnosing and treating the ingested and impacted dental prosthesis in the esophagus and their complications. This retrospective study analyzed patient’s chart whose underwent esophagoscopy for removing the impacted dental prosthesis in Dr. Cipto Mangunkusumo General Hospital, Jakarta, Indonesia during a period between January 1997 and December 2003. Neck-chest X-ray and esophagoscopy were performed in all patients to identify the existence of the dental prosthesis as a diagnostic and treatment procedure. The length of time for removing the dental prosthesis was recorded and stated as a less difficult esophagoscopy when it takes time less than 60 minutes and as a difficult  esophagoscopy takes 60 minutes or longer. Some risk difficulties factors were statistically analyzed. There were 53 patients of ingested dental prosthesis in esophagus. Only 51 cases were analyzed According to the length of time for removing the dental prosthesis by esophagoscopy, 22 patients were recorded as less difficult cases and 29 patients as difficult cases. Two cases among the cases needed cervicotomy after unsuccessful esophagoscopy removal. The difficulties to diagnose an impacted dental prosthesis in the esophagus caused by unreliable clinical history, unclear signs and symptoms, unable to be detected by X-ray and was not found during esophagoscopy. The difficulties in treating due to mucosal laceration, edema, bleeding, failure of the first extraction and conformity with the size and shape, the wire outside the dental prosthesis and the length of time stayed in the esophagus. (Med J Indones 2005; 14: 33-6Keywords: ingested dental prosthesis, radioluscent foreign body, length of time of esophagoscopy