1,371 research outputs found
Tests for Trends in Binary Response
Tests for trend in binary response are especially important when analyzing animal experiments where the response in various dose--groups is of interest. Among the nonparametric tests the approach of Cochran and Armitage is the one which is most commonly used. This test (CA-test) is actually a test for a linear trend. The result of this test is highly dependent on the quantification of the dose. Varying score assignments can lead to totally different results. As an alternative isotonic regression is proposed. The result of this approach is independent of any monotonic transformation of the dose. The p--value related with the isotonic regression can be obtained either from considering all possible combinations of the total number of events in the dose--groups or by analyzing a random sample of all permutations. Both tests are compared within a simulation--study and on data from an experiment considering whether a certain type of fibre, para--aramid, is carcinogenic. The result of the commonly used CA--test is highly dependent on the event rate in the lowest and highest dose--group. Based on our analyses we recommend to use the isotonic regression instead of the test proposed by Cochran and Armitage
Two Results on Slime Mold Computations
We present two results on slime mold computations. In wet-lab experiments
(Nature'00) by Nakagaki et al. the slime mold Physarum polycephalum
demonstrated its ability to solve shortest path problems. Biologists proposed a
mathematical model, a system of differential equations, for the slime's
adaption process (J. Theoretical Biology'07). It was shown that the process
convergences to the shortest path (J. Theoretical Biology'12) for all graphs.
We show that the dynamics actually converges for a much wider class of
problems, namely undirected linear programs with a non-negative cost vector.
Combinatorial optimization researchers took the dynamics describing slime
behavior as an inspiration for an optimization method and showed that its
discretization can -approximately solve linear programs with
positive cost vector (ITCS'16). Their analysis requires a feasible starting
point, a step size depending linearly on , and a number of steps
with quartic dependence on , where is
the difference between the smallest cost of a non-optimal basic feasible
solution and the optimal cost ().
We give a refined analysis showing that the dynamics initialized with any
strongly dominating point converges to the set of optimal solutions. Moreover,
we strengthen the convergence rate bounds and prove that the step size is
independent of , and the number of steps depends logarithmically
on and quadratically on
Algorithms for routing in planar graphs
We present algorithms for solving routing problems for two-terminal nets in planar graphs. Our algorithms run in time O(n2) for general planar graphs and in time O(bn) for grid graphs where n is the number of vertices and b is the number of vertices on the boundary of the infinite face
20 Years of Microplasma Research: A Status Report
The field of microplasmas gained recognition as a well-defined area of research and application within the larger field of plasma science and technology about 20 years ago. Since then, the activity in microplasma research and applications has continuously increased. A survey of peer reviewed papers on microplasmas published annually shows a steady increase from fewer than 20 papers in 1995 to about 75 in 2005 and more than 150 in 2014. This count excludes papers that deal exclusively with technological applications where the microplasma is used solely as a tool. This topical review aims to provide a snap shot of the current state of microplasma research and applications. Given the rapid proliferation of microplasma applications, the topical review will focus primarily on the status of microplasma science and our understanding of the physics principles that enable microplasma operation. Where appropriate, we will also address microplasma applications, however, we will limit the discussion of microplasma applications to examples where the application is closely tied to the plasma science. No attempt is made to provide a comprehensive and in-depth review of the diverse range of all microplasma applications, except for the inclusion of a few key references to recent reviews of microplasma applications
Final report: A participatory method for need based capacity development projects and programmes
The three-year research project funded by MSB applies design science, in combination with traditional scientific investigation, to develop a method to guide the planning phase of capacity development projects for disaster risk reduction and climate change adaptation. The method facilitates local participation and ownership as it builds on the strengths of the Logical Framework Approach (LFA), while contextualising it to suit capacity development for disaster risk management and climate change adaptation
Board 87: Work in Progress WIP Comparing the most demanded skills for Electrical and Computer Engineers (ECE) Graduates in the United States from the Perspective of ECE Academic Department Heads and ECE Professional Engineers
When students graduate from an Electrical and Computer Engineering (ECE) program, there is a discrepancy or imbalance between the job-related competencies that firms require and what academic institutions deliver. As a result, there are more graduates who lack the skills that the market dictates. Due to the skills gap, recently recruited engineers may still need more training to gain necessary competencies, costing companies both time and money. The primary purpose of this study is to compare the skills ECE graduates should have upon graduation from ECE industry perspective and ECE academic department heads’ perspectives. In this context, this paper presents the outcomes of two surveys, one distributed to ECE professional engineers and the other to ECE department heads in the U.S. Both surveys used in this study were obtained from The College and Career Readiness and Success Center at the U.S. Department of Education. The surveys focus on nine major categories: applied academic skills, critical thinking skills, interpersonal skills, personal skills, resource management skills, information use skills, communication skills, system thinking skills, and technology use skills. In addition, ECE professional engineers and ECE department heads were asked to rank several skills on a 1-5 Likert scale, where one is not important and five is vital. Forty-five ECE department heads and 45 ECE professionals completed the surveys regarding the required skills ECE graduates should possess upon graduation and how vital these skills are. The results of the surveys highlight the gap between academic outcomes and industry expectations for ECE graduates. System thinking, communication, and resource management skills are the most important skills for ECE graduates from an ECE professional engineer’s point of view. Furthermore, ECE department heads believed that applied academic skills, critical thinking skills, and technology use skills are the most important, highlighting the difference between academia and industry. Furthermore, independent samples t-test was utilized to compare the data from the two surveys to determine whether statistically significant differences existed between the department head\u27s and professional engineers\u27 assessments of the technical aptitude of Electrical and Computer Engineering graduates
Collisional and Radiative Processes in High-Pressure Discharge Plasmas
Discharge plasmas at high pressures (up to and exceeding atmospheric pressure), where single collision conditions no longer prevail, provide a fertile environment for the experimental study of collisions and radiative processes dominated by (i) step-wise processes, i.e., the excitation of an already excited atomic/molecular state and by (ii) three-body collisions leading, for instance, to the formation of excimers. The dominance of collisional and radiative processes beyond binary collisions involving ground-state atoms and molecules in such environments allows for many interesting applications of high-pressure plasmas such as high power lasers, opening switches, novel plasma processing applications and sputtering, absorbers and reflectors for electromagnetic waves, remediation of pollutants and waste streams, and excimer lamps and other noncoherent vacuum-ultraviolet light sources. Here recent progress is summarized in the use of hollow cathode discharge devices with hole dimensions in the range 0.1-0.5 mm for the generation of vacuum-ultraviolet light
Cluster Issue on Microplasmas
Atmospheric-pressure diffuse discharge plasmas are susceptible to instabilities and, in particular, to arcing (the glow-to-arc transition). Some of the most promising approaches to ‘stabilizing’ atmospheric-pressure plasmas are based on the recognition that arc formation can be avoided when the plasmas are generated and maintained in spatially constricted geometries with dimensions from tens to hundreds of microns. Known as microplasmas or microdischarges, these weakly-ionized discharges represent a new and fascinating realm of plasma science in which several scientific issues, such as the potential breakdown of pd scaling and the role of boundary-based phenomena, come to the fore. In contrast to ‘macroplasmas’ typically produced at pressures well below one atmosphere, high-pressure microdischarges offer the formation of transient molecular species, such as the rare gas excimers, that are generated by three-body collisions. When excited with sub-microsecond pulses, microplasmas can exhibit significant shifts in electron and ion temperatures and in the electron and ion energy distribution functions, which can be exploited in applications such as intense UV/VUV light sources and for the selective production of chemically reactive radicals. The technological applications of these stable high-pressure microplasmas have outpaced the detailed understanding of the plasma physics and the key processes in these plasmas on a microscopic level
Invasive home mechanical ventilation, mainly focused on neuromuscular disorders
Introduction and background Invasive home mechanical ventilation is used for patients with chronic respiratory insufficiency. This elaborate and technology-dependent ventilation is carried out via an artificial airway (tracheal cannula) to the trachea. Exact numbers about the incidence of home mechanical ventilation are not available. Patients with neuromuscular diseases represent a large portion of it. Research questions Specific research questions are formulated and answered concerning the dimensions of medicine/nursing, economics, social, ethical and legal aspects. Beyond the technical aspect of the invasive home, mechanical ventilation, medical questions also deal with the patient's symptoms and clinical signs as well as the frequency of complications. Economic questions pertain to the composition of costs and the differences to other ways of homecare concerning costs and quality of care. Questions regarding social aspects consider the health-related quality of life of patients and caregivers. Additionally, the ethical aspects connected to the decision of home mechanical ventilation are viewed. Finally, legal aspects of financing invasive home mechanical ventilation are discussed. Methods Based on a systematic literature search in 2008 in a total of 31 relevant databases current literature is viewed and selected by means of fixed criteria. Randomized controlled studies, systematic reviews and HTA reports (health technology assessment), clinical studies with patient numbers above ten, health-economic evaluations, primary studies with particular cost analyses and quality-of-life studies related to the research questions are included in the analysis. Results and discussion Invasive mechanical ventilation may improve symptoms of hypoventilation, as the analysis of the literature shows. An increase in life expectancy is likely, but for ethical reasons it is not confirmed by premium-quality studies. Complications (e. g. pneumonia) are rare. Mobile home ventilators are available for the implementation of the ventilation. Their technical performance however, differs regrettably.Studies comparing the economic aspects of ventilation in a hospital to outpatient ventilation, describe home ventilation as a more cost-effective alternative to in-patient care in an intensive care unit, however, more expensive in comparison to a noninvasive (via mask) ventilation. Higher expenses arise due to the necessary equipment and the high expendi tur e of time for the partial 24-hour care of the affected patients through highly qualified personnel. However, none of the studies applies to the German provisionary conditions. The calculated costs strongly depend on national medical fees and wages of caregivers, which barely allows a transmission of the results.The results of quality-of-life studies are mostly qualitative. The patient's quality of life using mechanical ventilation is predominantly considered well. Caregivers of ventilated patients report positive as well as negative ratings. Regarding the ethical questions, it was researched which aspects of ventilation implementation will have to be considered.From a legal point of view the financing of home ventilation, especially invasive mechanical ventilation, requiring specialised technical nursing is regulated in the code of social law (Sozialgesetzbuch V). The absorption of costs is distributed to different insurance carriers, who often, due to cost pressures within the health care system, insurance carriers, who consider others and not themselves as responsible. Therefore in practice, the necessity to enforce a claim of cost absorption often arises in order to exercise the basic right of free choice of location. Conclusion Positive effects of the invasive mechanical ventilation (overall survival and symptomatic) are highly probable based on the analysed literature, although with a low level of evidence. An establishment of a home ventilation registry and health care research to ascertain valid data to improve outpatient structures is necessary. Gathering specific German data is needed to adequately depict the national concepts of provision and reimbursement. A differentiation of the cost structure according to the type of chosen outpatient care is currently not possible. There is no existing literature concerning the difference of life quality depending on the chosen outpatient care (homecare, assisted living, or in a nursing home specialised in invasive home ventilation). Further research is required.For a so called participative decision - made by the patient after intense counselling - an early and honest patient education pro respectively contra invasive mechanical ventilation is needed. Besides the long term survival, the quality of life and individual, social and religious aspects have also to be considered.Einleitung und Hintergrund Die invasive Heimbeatmung wird bei Patienten mit chronisch respiratorischer Insuffizienz (unzureichender Atemfähigkeit) durchgeführt. Die aufwendige und technologielastige Beatmung erfolgt über einen künstlichen Zugang (Trachealkanüle) zur Luftröhre. Genaue Zahlen über die Häufigkeit dieser Form von Beatmung in häuslicher Umgebung liegen nicht vor. Patienten mit neuromuskulären Erkrankungen machen einen großen Anteil aus. Forschungsfragen Zu unterschiedlichen Dimensionen Medizin/Pflege, Ökonomie, Soziales, Ethik und Recht werden spezifische Forschungsfragen formuliert und beantwortet. Medizinische Fragen behandeln neben technischen Aspekten der häuslichen invasiven Beatmung, die Symptomatik bzw. die klinischen Befunde der Patienten sowie die Häufigkeit von Komplikationen. Ökonomische Fragestellungen beziehen sich auf die Zusammensetzung der Kosten und die Unterschiede zu anderen Versorgungsformen bezüglich Kosten und Qualität der Pflege. Fragestellungen zu sozialen Aspekten berücksichtigen die gesundheitsbezogene Lebensqualität der Patienten und Betreuungspersonen. Zusätzlich werden die mit der Entscheidung zu Heimbeatmung verbundenen ethischen Gesichtspunkte betrachtet. Zuletzt werden rechtliche Aspekte der Finanzierung der invasiven Heimbeatmung erörtert. Methodik Auf Basis einer systematischen Literatursuche 2008 in insgesamt 31 relevanten Datenbanken wird die derzeit aktuelle Literatur gesichtet und anhand festgelegter Kriterien ausgewählt. Randomisierte kontrollierte Studien, systematische Reviews und HTA-Berichte (HTA = Health Technology Assessment), klinische Studien mit Patientenzahlen über zehn, gesundheitsökonomische Evaluationen, Primärstudien ggf. mit eigenen Kostenberechnungen und Lebensqualitätsstudien mit Bezug zu den Forschungsfragen führen zum Einschluss in die Analyse. Ergebnisse und Diskussion Invasive Beatmung kann die Symptome der Hypoventilation verbessern, wie sich aus der Analyse der Literatur ergibt. Darüber hinaus ist eine Lebensverlängerung wahrscheinlich, jedoch aus ethischen Gründen nicht durch qualitativ hochwertige Studien abgesichert. Komplikationen (z. B. Pneumonie) treten relativ selten auf. Für die Durchführung der Beatmung stehen mobile Heimbeatmungsgeräte zur Verfügung, deren technische Performance leider sehr unterschiedlich ist.Studien, die die ökonomischen Aspekte der Beatmung im Krankenhaus mit der außerklinischen Beatmung vergleichen, beschreiben Heimbeatmung als kostengünstigere Alternative zur stationären Versorgung auf einer Intensivstation, jedoch als teuerer im Vergleich zur nichtinvasiven (über Maske) Beatmung. Die höheren Aufwendungen entstehen aufgrund des notwendigen Equipments und des hohen Zeitaufwands für die teilweise 24-stündige Pflege der betroffenen Patienten durch hochqualifiziertes Personal. Jedoch bezieht sich keine der Studien auf den deutschen Versorgungskontext. Die ermittelten Kosten sind stark von nationalen Honorarplänen und Arbeitslöhnen der Pflegedienste abhängig, was eine Übertragung kaum zulässt.Ergebnisse von Lebensqualitätsstudien sind meistens qualitativ. Die Lebensqualität der Patienten unter Beatmung wird von ihnen selbst überwiegend als gut bewertet. Bei den Pflegepersonen von beatmeten Patienten zeigen sich sowohl positive als auch negative Einschätzungen. Im Hinblick auf die ethischen Fragestellungen wurde untersucht, welche Aspekte bei der Beatmungseinleitung berücksichtigt werden müssen. Rechtlich gesehen ist die Finanzierung der häuslichen Beatmung, v. a. bei invasiver Beatmung mit der Notwendigkeit einer Behandlungspflege, durch das Sozialgesetzbuch (SGB) V geregelt. Die Übernahme der Kosten verteilt sich auf verschiedene Kostenträger, die häufig, u. a. aufgrund des allgemeinen Kostendrucks im Gesundheitswesen, nicht sich selbst, sondern andere in der Pflicht sehen. Deswegen ergibt sich in der Praxis häufig die Notwendigkeit, die Kostenübernahme vor Gericht einzuklagen, um das Grundrecht auf freie Wahl des Aufenthaltsorts wahrnehmen zu können. Schlussfolgerung Positive Effekte der invasiven Heimbeatmung (Gesamtüberleben und Symptomatik) sind aufgrund der analysierten Literatur hochwahrscheinlich, wenn auch nur mit geringer Evidenz belegt. Hier ist durch Aufbau eines Heimbeatmungs-Registers und der Versorgungsforschung die Erhebung valider Daten, zur Verbesserung ambulanter Strukturen, notwendig. Die Erhebung von deutschen Daten ist notwendig, um nationale Versorgungs- und Vergütungskonzepte adäquat darstellen zu können. Eine Differenzierung der Kostenstruktur nach Art der gewählten außerklinischen Versorgung ist aktuell nicht möglich. Literatur bezüglich Unterschiede in der Lebensqualität in Abhängigkeit von der gewählten außerklinischen Versorgungsform (Versorgung in der eigenen Wohnung, in einer betreuten Wohngruppe oder im auf invasive Beatmung spezialisierten Pflegeheim) existiert nicht. Auch hier herrscht weiterer Forschungsbedarf.Eine frühzeitige und ehrliche Patientenaufklärung ist für eine sogenannte partizipative Entscheidung - die eigenständig durch den Patienten nach eingehender Aufklärung und Beratung getroffen wird - pro bzw. kontra invasive Beatmung notwendig. Neben dem Langzeitüberleben müssen auch Lebensqualität und individuelle, soziale sowie religiöse Aspekte berücksichtigt werden
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