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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Effects of reinforcer density versus reinforcement schedule on human behavioral momentum

Slivinski, James G. 30 March 2009 (has links)
The essential tenet of the behavioral momentum model (BMM) is that relative response rate decreases less in the face of disruption when maintained by a higher reinforcer density. Empirical support exists based on both response-dependent and response-independent reinforcement. In the present study the BMM was tested with college students in 4 multi-element experiments, each using 2 reinforcement schedules and a disrupter. Participants performed a categorical sort (by orientation) of triangles on a computer monitor. Sorting response rates were disrupted by a concurrent task, pressing the keyboard “T” key whenever 2 displayed changing numbers were equal. Initial training established fast (under VR 4) and slow (under DRL 5-s) sorting rates, and provided practice with the disrupting task. In Experiment 1 DRL 5-s provided higher reinforcer density, while in Experiment 2 VR 4 did. In Experiment 3 the higher total reinforcer density was achieved by adding VT 6-s to DRL 5-s while in Experiment 4 it was achieved by adding VT 12-s to VR 4. In all 4 experiments, sorting rate decreased with introduction of the disrupter. In Experiments 1 and 3, relative sorting rate decreased less under DRL based schedule (greater reinforcer density), supporting the BMM. However, in Experiments 2 and 4, relative sorting also decreased less under DRL (lower reinforcer density), contrary to the BMM prediction. Taken together, these data show greater relative resistance to change under DRL (versus VR), independent of reinforcer density. Thus, contrary to the BMM, the nature of the reinforcement schedule seemed to be the principal factor determining behavioral momentum.
122

From Block to Traditional Schedule: The Impact on Academic Achievement, Attendance Rates, and Dropout Rates

Schott, Patrick W. 05 1900 (has links)
The purpose of this study was to examine the impact of school schedule on student achievement and attendance of ninth and tenth grade students in metropolitan area Texas high schools (n = 22) and campus dropout rates. High schools that were analyzed in this study made a transition from A/B block scheduling in the 2003-04 school year to a traditional school schedule in the 2004-05 school year. Academic achievement, attendance rates and dropout rates were gathered through the archived files of the Texas Agency through the Academic Indicator of Excellence System (AEIS). Academic achievement was measured by the Texas Assessment of Knowledge and Skills (TAKS) Reading/Language Arts and Mathematics standardized tests. This study compared the mean scores of ninth grader student achievement, attendance, and dropout rates from the 2003-04 school year to the mean scores of the tenth graders from the same schools from the 2004-05 school year, after the schools converted from an A/B block schedule to a traditional class schedule. Each independent variable was divided into four subgroups; campus mean results, minority student results, limited English proficient (LEP) student results, and low-socioeconomic student results. Students under the A/B block scored significantly higher in reading achievement than when they were instructed the following year under a traditional schedule. Paired sample t-tests were conducted to analyze the data for each subgroup, and showed there was a statistically significance in reading / language arts student achievement scores for all subgroups. Statistical significance was determined with a ninety five percent confidence level (p < 0.05). Statistical analysis revealed varied results in mean scores for math academic achievement and attendance rates, but no statistical significant difference. Comparison of data showed a slight increase in mean scores for dropout rates in traditional schedule, however the results were not significant.
123

The frequency of social dysfunction in a general population sample and in patients with mental disorders: A comparison using the Social Interview Schedule (SIS)

Hecht, Heidemarie, Wittchen, Hans-Ulrich January 1988 (has links)
The frequency of social dysfunctions in a general population sample and in different diagnostic groups was investigated by using the Social Interview Schedule (SIS). Based on the results of the general population sample, several of the a priori derived cut-off scores of the SIS were modified. The analysis of the general population sample revealed sex-specific relationships between age and different aspects of social functioning. Especially for younger women significantly more objective social restrictions, were found due to the burden of multiple role responsibilities. With regard to different diagnostic subgroups including patients and mostly untreated cases from the community sample with Affective Disorders and Anxiety Disorders, results indicate that the degree of social impairment and dysfunctions and the degree of satisfaction with different role areas are strongly dependent on type of disorder and on former treatment status. Specific findings are: (1) The highest number of social impairments and dysfunctions were found in cases and patients with affective syndromes and in schizophrenic patients, but not in schizoaffective patients. (2) Management difficulties and dissatisfaction in intimate relationships were primarily found in depressed women. (3) Unlike anxiety patients, anxiety cases, although mostly chronically ill, had significantly less objective impairments and a lower rate of dissatisfaction than depressed cases. The results are discussed with special reference to the possible key role of depression for the development of social dysfunctions, as measured by the SIS. (4) Problems were, however, acknowledged concerning the use of the SIS with severely disturbed chronic schizophrenic patients.
124

Procedural validity of standardized symptom questions for the assessment of psychotic symptoms: A comparison of the DIS with two clinical methods

Spengler, Peter A., Wittchen, Hans-Ulrich January 1988 (has links)
The study examines to what degree well-documented present and life-time psychotic symptoms in a group of former psychiatric inpatients are ascertained when using the Diagnostic Interview Schedule (DIS). The Inpatient Multidimensional Psychiatric Scale (IMPS) and the Manual for the Assessment and Documentation of Psychopathology/Diagnostische Sichtlochkartei (AMDP/DiaSika) Interview-Checklist approach were used for the “clinical” evaluations of symptoms. The results indicate fair concordance between the two clinical approaches and the DIS with regard to the presence of any delusional or hallucination symptoms. Low to poor agreement was found in the assessment of many of the rather specific hallucinations and delusions. Generally, the concordance found was higher when compared to the more clinical AMDP/DiaSiKa approach than to the IMPS. More detailed comparisons with diagnostic subgroups of schizophrenic and schizoaffective patients substantiated the findings in the overall sample. Overall it was reconfirmed that the DIS approach is limited to those patients who are cooperative and at least partly remitted.
125

[pt] OTIMIZAÇÃO DE RECURSOS PARA PROCEDIMENTOS CIRÚRGICOS ELETIVOS UTILIZANDO ALGORITMOS GENÉTICOS COM INSPIRAÇÃO QUÂNTICA / [en] RESOURCE OPTIMIZATION FOR ELECTIVE SURGICAL PROCEDURES USING QUANTUM-INSPIRED GENETIC ALGORITHMS

RENE GONZALEZ HERNANDEZ 29 March 2019 (has links)
[pt] Atualmente as Unidades de Saúde, em um grande número de países do mundo, apresentam demandas de serviços que superam suas capacidades reais. Por esta razão, o surgimento das listas de espera é inevitável. Preparar o planejamento das mesmas, de modo otimizado resulta, portanto, em um grande desafio, devido à quantidade de recursos que devem ser considerados. O caso particular dos procedimentos cirúrgicos é particularmente crítico pela quantidade de recursos que se precisam para a realização do mesmo. Poucos projetos têm sido desenvolvidos para a gestão completa dessas listas. O trabalho desenvolvido nesta Dissertação propõe o uso de um modelo, baseado em algoritmos genéticos com inspiração quântica, para a automatização e otimização do planejamento de procedimentos cirúrgicos eletivos. Este modelo, denominado Algoritmo Evolucionário com Inspiração Quântica para a Área de Saúde (AEIQ-AS), além de alocar os pacientes e os recursos necessários para que o processo cirúrgico seja exitoso, procura reduzir o tempo total para que todas as cirurgias sejam realizadas. Este trabalho apresenta também uma ferramenta que permite a modelagem, de modo simplificado, de uma Unidade Cirúrgica de Saúde. Esta ferramenta possibilita a realização de simulações com o objetivo de ver o efeito de diferentes configurações dos recursos nas Unidades de Saúde. Para a validação do modelo proposto foi criada, de modo artificial e fazendo uso da ferramenta de simulação, uma lista de espera de 2000 cirurgias. Caso as cirurgias fossem realizadas seguindo a ordem de chegada, seriam necessárias pouco mais de 37 semanas e teria 1066 operações fora do prazo. Foram feitos vários experimentos onde se buscava a otimização destes valores. Esta busca foi feita, primeiramente, tomando em consideração só um dos parâmetros e a continuação eles em conjunto. Na primeira abordagem o AEIQ-AS consegue a realização das mesmas cirurgias em aproximadamente 31 semanas. Assim, observa se que há uma redução de aproximadamente 16,25 porcento do tempo. O número de operações fora do prazo, por sua vez, foi reduzido pelo modelo para 927 (13,04 porcento). Na abordagem simultânea, o AEIQ-AS, consegue uma diminuição do tempo total de alocação em 16,22 porcento e o número de operações fora do prazo em 9,76 porcento. Foram feitas, também, várias simulações da Unidade de Saúde mantendo as caraterísticas da lista de cirurgias para ver seu efeito no tempo total de alocação de todos os processos cirúrgicos. / [en] Currently, Health Units in a large number of countries in the world present service demand that exceed their real capacities. For this reason, is inevitable the emergence of the waiting lists. To prepare the planning of this in an optimized manner results in a substantial challenge due to the number of resources that should be considered. The case of chirurgical procedures is particularly critical by the number of resources needed for their realization. A small quantity of projects has been developed to fully manage these lists. The work developed in this Dissertation proposes the use of a model based on evolutionary algorithms with quantum inspiration for the automation and optimization of the planning of elective chirurgical procedures. This model, denominated Evolutionary Algorithm with Quantum Inspiration for the Health Field (AEIQ-AS), beyond patients and necessary resources for the successful completion of the chirurgical procedure allocation, pursue the reduction of the total time of realization of all the surgeries. The work presents also a tool that allows the modeling, in a simplified manner, of a Chirurgical Health Unit. This tool enables the realization of simulations with the objective of seeing the effect of different configurations of the resources in the Health Units. To validate the proposed model was created, in artificial mode and employing the simulation tool, a waiting list of 2000 surgeries. In case that the surgeries were realized following the arrival order, will be needed a little more than 37 weeks and will have 1066 surgeries out of time. Several experiments were conducted in order to optimize these values. This search was executed, firstly, considering only one of the parameters and, in continuation, all together. In the first approach, the AEIQ-AS obtains the realization of the same surgeries in approximately 16,25 percent of the time. The number of operations out of time was reduced by the model to 927 (13,04 percent). In the simultaneous approach, the AEIQAS achieves a decrease of the allocation total time in 16,22 percent and the number of operations out of time in 9,76 percent. It were done, also, several simulations of the Health Unit maintaining the characteristics of the surgeries list in order to look the effect in the allocation total time of all the chirurgical procedures.
126

Best practices for automation and control of mine dewatering systems / Phillip Johannes Oberholzer

Oberholzer, Phillip Johannes January 2015 (has links)
Typical deep level mines use up to 27 ML water per day for mining operations. Multistage centrifugal pumps up to 2500 MW are used in an upward cascading manor to dewater the shaft. The dewatering systems at some mines are automated to enable surface control. Automation of the pumps is typically based on the best practice procedure known when implemented. Best practice procedures are used to ensure safe pumping operations. It was found that pump failures could still occur even with the best practice implemented. Unexpected failures of pumps are of major concern because they can result in the flooding of a mine. Flooding increases the risk of environmental damage and injury to the mining personnel. An additional concern is the maintenance cost of multistage centrifugal pumps. Overhaul cost of a seized multistage centrifugal pump is almost R1-million. The aim of this study was to improve established best practice procedures for pump automation. This could be achieved by investigating the general root cause of failures of automated pumps. Additional instrumentation and protection devices to prevent similar incidents were examined. Revised system control parameters were developed to ensure that the pumps operated within the design specifications. The improved best practices proved to prevent failures as a result of overheating and cavitation. Increasing the pump reliability and availability enabled surface control. The control of the automated dewatering system realised an electricity cost saving of R6-million. The automated system also made it possible to calculate the real-time pump efficiency within 5%. Previous best practice procedure was found to be inadequate to prevent all possibilities of failure. Additional precaution measurements were added to prevent pump failure. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015
127

Best practices for automation and control of mine dewatering systems / Phillip Johannes Oberholzer

Oberholzer, Phillip Johannes January 2015 (has links)
Typical deep level mines use up to 27 ML water per day for mining operations. Multistage centrifugal pumps up to 2500 MW are used in an upward cascading manor to dewater the shaft. The dewatering systems at some mines are automated to enable surface control. Automation of the pumps is typically based on the best practice procedure known when implemented. Best practice procedures are used to ensure safe pumping operations. It was found that pump failures could still occur even with the best practice implemented. Unexpected failures of pumps are of major concern because they can result in the flooding of a mine. Flooding increases the risk of environmental damage and injury to the mining personnel. An additional concern is the maintenance cost of multistage centrifugal pumps. Overhaul cost of a seized multistage centrifugal pump is almost R1-million. The aim of this study was to improve established best practice procedures for pump automation. This could be achieved by investigating the general root cause of failures of automated pumps. Additional instrumentation and protection devices to prevent similar incidents were examined. Revised system control parameters were developed to ensure that the pumps operated within the design specifications. The improved best practices proved to prevent failures as a result of overheating and cavitation. Increasing the pump reliability and availability enabled surface control. The control of the automated dewatering system realised an electricity cost saving of R6-million. The automated system also made it possible to calculate the real-time pump efficiency within 5%. Previous best practice procedure was found to be inadequate to prevent all possibilities of failure. Additional precaution measurements were added to prevent pump failure. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015
128

Optimering och balansering av cyklisk produktion : En studie på Sandvik Materials Technology PU Borrstål

Hedlund, Tommy, Kvarnlöf, Daniel January 2016 (has links)
Aim: The purpose of this study is to present and test an algorithm that gives acceptable solutions in the optimization of a dedicated production line consisting of several machines, with regards of inventory holding cost and available capacity. The aim is also to suggest possible improvements in the practical case that has been used to test the model, which have been made in cooperation with Sandvik Materials Technology and it’s product unit Rock Drill Steel, located in Sandviken, Sweden. Method: An algorithm has been elaborated from articles and science reports and has then been tested with data from the practical case. The result has then been evaluated through an analysis where the algorithm’s ability to acceptable solutions and show potential savings with regards to capital tied up in stock of finished products, safety stock and products in work in process. Results and conclusions: The study shows that the algorithm has the ability to create acceptable solutions when given a specific demand rate, cycle time and capacity. The study also shows potential savings when using a shorter production cycle, given that the unit works in a structured way in order to shorten the production cycle. Suggestions for future research: The algorithm tested in this study needs more evaluations regarding its limits and possible benefits through practical and theoretical case studies. Contributions: The algorithm the possibility to combine principles and models aimed at solving the ELSP (Economic Lot Schedule Problem) and the principles of Schedule Leveling, which is a common term in lean production to a model that optimize inventory holding costs. These theories have similar approaches to cyclic production, but have different aims. Key words: cyclic scheduling, ELSP, economic lot size problem, schedule leveling, heijunka, lean production / Titel: Optimering och balansering av cyklisk produktion - en studie på Sandvik Materials Technology PU Borrstål Nivå: C-uppsats i ämnet Industriell Ekonomi Författare: Tommy Hedlund, Daniel Kvarnlöf Handledare: Mohammad Abid Datum: 2016 - Mars Syfte: Studiens syfte är att presentera och testa en algoritm som ger godkända resultat vid optimering av en dedikerad produktionslina bestående av flera produktionsresurser, med avseende på lagerhållningskostnad i omsättningslager samt tillgänglig kapacitet, samt att presentera möjliga förbättringsförslag utifrån de resultat som ges i det praktiska fall som simuleringsmodellen utvärderas genom. Det praktiska fallet i denna studie är Sandvik Materials Technology och dess produktenhet Borrstål. Metod: Studien har genomförts genom att en algoritm har tagits fram utifrån artiklar och forskningsrapporter på området, som sedan har prövats mot studiens praktiska fall. Resultatet har sedan utvärderats genom en analys av algoritmens förmåga att ge godkända lösningar, samt möjlig besparingspotential i det aktuella fallet utifrån kapitalbindning i omsättningslager, säkerhetslager och produkter i arbete. Resultat &amp; slutsats: Studien visar att algoritmen har en god förmåga att skapa godkända resultat utifrån en specifik efterfrågan, cykeltid och kapacitet. Studien visar även på stora potentiella besparingar i kapitalbindning till följd av kortare cykeltid i såväl omsättningslager, säkerhetslager och produkter i arbete, givet att produktenheten arbetar strukturerat med att söka minska cykeltiden. Förslag till fortsatt forskning: Algoritmen behöver ytterligare forskning kring dess begränsningar genom att utvärderas utifrån fler praktiska och teoretiska fall. Uppsatsens bidrag: Algoritmen visar på en möjlighet att kombinera ELSP (economic lot scheduling problem) och dess modeller med de principer som återfinns inom Schedule Leveling, som är ett vanligt begrepp inom lean production. Dessa teorier liknar varandra men har till viss del skilda syften, vilka kan kombineras till en modell som optimerar produktionen med avseende på lagerhållningskostnaderna.
129

Optimization approaches for designing baseball scout networks under uncertainty

Ozlu, Ahmet Oguzhan 27 May 2016 (has links)
Major League Baseball (MLB) is a 30-team North American professional baseball league and Minor League Baseball (MiLB) is the hierarchy of developmental professional baseball teams for MLB. Most MLB players first develop their skills in MiLB, and MLB teams employ scouts, experts who evaluate the strengths, weaknesses, and overall potential of these players. In this dissertation, we study the problem of designing a scouting network for a Major League Baseball (MLB) team. We introduce the problem to the operations research literature to help teams make strategic and operational level decisions when managing their scouting resources. The thesis consists of three chapters that aim to address decisions such as how the scouts should be assigned to the available MiLB teams, how the scouts should be routed around the country, how many scouts are needed to perform the major scouting tasks, are there any trade-off s between the scouting objectives, and if there are any, what are the outcomes and insights. In the first chapter, we study the problem of assigning and scheduling minor league scouts for Major League Baseball (MLB) teams. There are multiple objectives in this problem. We formulate the problem as an integer program, use decomposition and both column-generation-based and problem-specific heuristics to solve it, and evaluate policies on multiple objective dimensions based on 100 bootstrapped season schedules. Our approach can allow teams to improve operationally by finding better scout schedules, to understand quantitatively the strategic trade-offs inherent in scout assignment policies, and to select the assignment policy whose strategic and operational performance best meets their needs. In the second chapter, we study the problem under uncertainty. In reality we observe that there are always disruptions to the schedules: players are injured, scouts become unavailable, games are delayed due to bad weather, etc. We presented a minor league baseball season simulator that generates random disruptions to the scout's schedules and uses optimization based heuristic models to recover the disrupted schedules. We evaluated the strategic benefits of different policies for team-to-scout assignment using the simulator. Our results demonstrate that the deterministic approach is insufficient for evaluating the benefits and costs of each policy, and that a simulation approach is also much more effective at determining the value of adding an additional scout to the network. The real scouting network design instances we solved in the first two chapters have several detailed complexities that can make them hard to study, such as idle day constraints, varying season lengths, off days for teams in the schedule, days where some teams play and others do not, etc. In the third chapter, we analyzed a simplified version of the Single Scout Problem (SSP), stripping away much of the real-world complexities that complicate SSP instances. Even for this stylized, archetypal version of SSP, we find that even small instances can be computationally difficult. We showed by reduction from Minimum Cost Hamiltonian Path Problem that archetypal version of SSP is NP-complete, even without all of the additional complexity introduced by real scheduling and scouting operations.
130

PRECLINICAL AND CLINICAL DEVELOPMENT OF THE LIPOPHILIC CAMPTOTHECIN ANALOGUE AR-67

Tsakalozou, Eleftheria 01 January 2013 (has links)
AR-67 is a lipophilic third generation camptothecin analogue, currently under early stage clinical trials. It acts by targeting Topoisomerase 1 (Top1), a nuclear enzyme essential for DNA replication and transcription and is present in two forms, the pharmacologically active lipophilic lactone and the charged carboxylate. In oncology patients participating in a phase I clinical trial, AR-67 lactone was the predominant species in plasma. Similarly to other camptothecins, the identified dose-limiting toxicities for AR-67 were neutropenia, thrombocytopenia and fatigue. In addition, in vitro metabolism studies indicated AR-67 lactone as a substrate for CYP3A4/5 as well as the UGT1A7 and UGT1A8 enzymes localizing in the liver and the gut. Numerous studies have demonstrated the over-expression of transporters in certain tumor types. Here, the effect of interactions between AR-67 and efflux or uptake transporters on the antitumor efficacy of AR-67 in vitro was studied. We showed that BCRP and MDR1 overexpression confers resistance to AR-67. Moreover, we demonstrated the therapeutic superiority of protracted dosing over more intense dosing regimens of AR-67 using xenografts models. Our studies indicated the schedule-dependent expression of Top1 and the preferential partitioning of AR-67 in the tumor tissue. We reason that these are factors that need to be taken into consideration when designing dosing schedules aiming to maximize efficacy. As most cytotoxic drugs, AR-67 has a narrow therapeutic window. Thus, it is essential to identify the variables influencing exposure to this camptothecin analogue. A thorough compartmental pharmacokinetic analysis was performed on the patient data obtained in a phase 1 clinical trial on AR-67. Moreover, sources of intersubject variability associated with obtaining pharmacokinetic parameter estimates were identified and a population covariate pharmacokinetic model was developed. In conclusion, the drug development of AR-67 is a work in process. Findings presented above provide an insight on the factors contributing to its efficacy and toxicity when given to cancer patients.

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