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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.
1

Structural control Architecture Optimization for 3-D Systems Using Advanced Multi-Objective Genetic Algorithms

Cha, Young Jin 14 January 2010 (has links)
The architectures of the control devices in active control algorithm are an important fact in civil structural buildings. Traditional research has limitations in finding the optimal architecture of control devices such as using predefined numbers or locations of sensors and dampers within the 2-and 3-dimensional (3-D) model of the structure. Previous research using single-objective optimization only provides limited data for defining the architecture of sensors and control devices. The Linear Quadratic Gaussian (LQG) control algorithm is used as the active control strategy. The American Society of Civil Engineers (ASCE) control benchmark building definition is used to develop the building system model. The proposed gene manipulation genetic algorithm (GMGA) determines the near-optimal Pareto fronts which consist of varying numbers and locations of sensors and control devices for controlling the ASCE benchmark building by considering multi-objectives such as interstory drift and minimizing the number of the control devices. The proposed GMGA reduced the central processing unit (CPU) run time and produced more optimal Pareto fronts for the 2-D and 3-D 20-story building models. Using the GMGA provided several benefits: (1) the possibility to apply any presuggested multi-objective optimization mechanism; (2) the availability to perform a objective optimization problem; (3) the adoptability of the diverse encoding provided by the GA; (4) the possibility of including the engineering judgment in generating the next generation population by using a gene creation mechanisms; and (5) the flexibility of the gene creation mechanism in applying and changing the mechanism dependent on optimization problem. The near-optimal Pareto fronts obtained offer the structural engineer a diverse choice in designing control system and installing the control devices. The locations and numbers of the dampers and sensors in each story are highly dependent on the sensor locations. By providing near-Pareto fronts of possible solutions to the engineer that also consider diverse earthquakes, the engineer can get normalized patterns of architectures of control devices and sensors about random earthquakes.
2

When a relationship ends: The role of attachment in romantic relationship loss

2013 November 1900 (has links)
Loss is an inevitable part of the human experience. How each individual reacts to loss may be affected by various factors (e.g. an individual’s attachment style). The current studies focused on how individuals respond to and cope with the loss of one type of attachment figure, specifically the loss of a romantic partner. The relationship between romantic loss and attachment theory is discussed and an integrated model of romantic relationship loss and attachment is proposed. This model accounts for various differences in how individuals respond to the loss of romantic relationships in young adulthood. Study 1 focused on the development of a revised form of the Inventory of Daily Widowed Life (IDWL; Caserta and Lund, 2007), which was labelled the Daily Activities After Relationship Loss (DAARL), to assess loss-orientation, restoration-orientation, and the oscillation between these processes following romantic relationship loss. This measure allowed for the assessment of coping in keeping with the constructs of the Dual Process Model of Bereavement (DPM; Stroebe & Schut, 1999), but allowed for these processes to be assessed in the context of romantic relationship loss as opposed to coping following the death of a loved one. Study 1 was comprised of two parts with differing samples: Part 1 included seven (four female) graduate students and undergraduate alumni in the social sciences as participants whereas Part 2 included ninety-seven (sixty-nine female) undergraduate psychology students. Participants were presented with proposed items for the new measure, as well as definitions of loss-oriented and restoration-oriented coping, and then were asked to categorize these items as loss-oriented coping, restoration-oriented coping, both, or other. Items yielding the highest levels of inter-rater agreement were used for the DAARL in Study 2. Study 2 focussed on the attachment relationship between former romantic partners, and how individuals coped with the loss of an attachment figure following the termination of a romantic relationship. One hundred and fifty-nine (one hundred and eleven female) individuals who had been broken up with or deemed their most recent romantic loss as being a mutual break-up were asked to complete a questionnaire packet containing measures of attachment style, coping behaviours following the loss, depression, anxiety, and socially desirable responding. A model of differences in coping with romantic relationship loss based on an individual’s attachment style was proposed and tested based on Stroebe, Schut, and Stroebe’s (2005) DPM and findings by Waskowic (2010; See Figure 4). Based on the findings from the current studies there are differences between the four types of attachment (i.e., secure, dismissing, preoccupied, and fearful) in how each copes with the loss of a romantic attachment figure. In light of the current findings, a revised model of romantic grief, which integrates the Dual Process Model of Bereavement within an attachment theoretical framework is offered (See Figure 5). This new model accounts for observed differences in the way individuals cope with the loss of a romantic relationship and suggests that researchers focus on the attachment relationship to explain variability in an individual’s response following romantic loss. The results of Study 2 provide support for the new integrated model and encourage others to consider using attachment theory, when examining how individuals with different attachment styles (i.e., secure, dismissing, preoccupied, and fearful) will respond to a romantic loss. Study 1 and 2 in conjunction also provide early stage support for the validity of the DAARL. Study 1 provided initial content validity by having independent raters assess items as being consistent with restoration-oriented or loss-oriented coping. Study 2 provided empirical support of the items selected as being consistent with their intended constructs by analyzing internal consistency and item-total correlations. The findings of Study 2 suggested that the dimensions proposed represented related, but distinct constructs. The current studies aimed to advance our understanding of the relationship between attachment theory and romantic relationship loss by expanding upon relevant theories and empirical findings for bereavement following a death to other forms of loss. Further, the findings are reported in regards to specific attachment styles, rather than the secure versus insecure distinction that has been commonly utilized when conducting research on attachment style differences. Implications and future directions for research are discussed.
3

Intensive Care Unit Competencies of New Nursing Graduates in Saudi Arabia, Nurse Educator and Preceptor Perspectives

2013 November 1900 (has links)
The purpose of this study was to describe the competencies needed by nursing intern students as identified by their preceptors and nurse educators, who choose to work as registered nurses in intensive care units in Saudi Arabia. The research questions this study investigated were 1) what do nurse preceptors and nurse educators believe are the competencies for new graduates to allow them to work safely in an intensive care unit in Saudi Arabia, 2) what are the competencies they should possess at the end of their internships. 3) Is there a difference between nurse educators and preceptors in the perception of required or expected competencies of the nursing role in the Intensive Care Unit (ICU)? Through the Interpretive Description methodology, data were collected through interviews, the guide for which was developed based on the Canadian Association of Critical Care Nurses standards for critical care nursing practice. The data were analyzed to identify common themes. Themes for intensive care unit competencies included: 1) needed skill competencies; 2) development of knowledge application competencies; and 3) strategies for quality improvement. A notable aspect of this study was the finding that Saudi Arabia, there was agreement among participants that nursing intern students were not prepared to work in ICU immediately after their internship year. Building on participants’ responses, nursing intern students may acquire satisfactory preparation during their internship through continuous evaluation, consistent guidance, extended time period, and orientation. Consequently, it represents a significant contribution to enriching the nursing intern students’ internship outcomes as well as the literature in the context of Saudi Arabia and in advancing the nursing workforce in Intensive Care Units in Saudi Arabia.
4

Weighted hypergroups and some questions in abstract harmonic analysis

2013 November 1900 (has links)
Weighted group algebras have been studied extensively in Abstract Harmonic Analysis.Complete characterizations have been found for some important properties of weighted group algebras, namely, amenability and Arens regularity. Also studies on some other features of these algebras, say weak amenability and isomorphism to operator algebras, have attracted attention. Hypergroups are generalized versions of locally compact groups. When a discrete group has all its conjugacy classes finite, the set of all conjugacy classes forms a discrete commutative hypergroup. Also the set of equivalence classes of irreducible unitary representations of a compact group forms a discrete commutative hypergroup. Other examples of discrete commutative hypergroups come from families of orthogonal polynomials. The center of the group algebra of a discrete finite conjugacy (FC) group can be identified with a hypergroup algebra. For a specific class of discrete FC groups, the restricted direct products of finite groups (RDPF), we study some properties of the center of the group algebra including amenability, maximal ideal space, and existence of a bounded approximate identity of maximal ideals. One of the generalizations of weighted group algebras which may be considered is weighted hypergroup algebras. Defining weighted hypergroups, analogous to weighted groups, we study a variety of examples, features and applications of weighted hypergroup algebras. We investigate some properties of these algebras including: dual Banach algebra structure, Arens regularity, and isomorphism with operator algebras. We define and study Folner type conditions for hypergroups. We study the relation of the Folner type conditions with other amenability properties of hypergroups. We also demonstrate some results obtained from the Leptin condition for Fourier algebras of certain hypergroups. Highlighting these tools, we specially study the Leptin condition on duals of compact groups for some specific compact groups. An application is given to Segal algebras on compact groups.
5

A comparison of item selection procedures using different ability estimation methods in computerized adaptive testing based on the generalized partial credit model

Ho, Tsung-Han 17 September 2010 (has links)
Computerized adaptive testing (CAT) provides a highly efficient alternative to the paper-and-pencil test. By selecting items that match examinees’ ability levels, CAT not only can shorten test length and administration time but it can also increase measurement precision and reduce measurement error. In CAT, maximum information (MI) is the most widely used item selection procedure. However, the major challenge with MI is the attenuation paradox, which results because the MI algorithm may lead to the selection of items that are not well targeted at an examinee’s true ability level, resulting in more errors in subsequent ability estimates. The solution is to find an alternative item selection procedure or an appropriate ability estimation method. CAT studies have not investigated the association between these two components of a CAT system based on polytomous IRT models. The present study compared the performance of four item selection procedures (MI, MPWI, MEI, and MEPV) across four ability estimation methods (MLE, WLE, EAP-N, and EAP-PS) under the mixed-format CAT based on the generalized partial credit model (GPCM). The test-unit pool and generated responses were based on test-units calibrated from an operational national test that included both independent dichotomous items and testlets. Several test conditions were manipulated: the unconstrained CAT as well as the constrained CAT in which the CCAT was used as the content-balancing, and the progressive-restricted procedure with maximum exposure rate equal to 0.19 (PR19) served as the exposure control in this study. The performance of various CAT conditions was evaluated in terms of measurement precision, exposure control properties, and the extent of selected-test-unit overlap. Results suggested that all item selection procedures, regardless of ability estimation methods, performed equally well in all evaluation indices across two CAT conditions. The MEPV procedure, however, was favorable in terms of a slightly lower maximum exposure rate, better pool utilization, and reduced test and selected-test-unit overlap than with the other three item selection procedures when both CCAT and PR19 procedures were implemented. It is not necessary to implement the sophisticated and computing-intensive Bayesian item selection procedures across ability estimation methods under the GPCM-based CAT. In terms of the ability estimation methods, MLE, WLE, and two EAP methods, regardless of item selection procedures, did not produce practical differences in all evaluation indices across two CAT conditions. The WLE method, however, generated significantly fewer non-convergent cases than did the MLE method. It was concluded that the WLE method, instead of MLE, should be considered, because the non-convergent case is less of an issue. The EAP estimation method, on the other hand, should be used with caution unless an appropriate prior θ distribution is specified. / text
6

The phiX174 Lysis Protein E: a Protein Inhibitor of the Conserved Translocase MraY

Zheng, Yi 2009 May 1900 (has links)
Most bacteriophages release progeny virions at the end of the infection cycle by lysis of the host. Large phages with double-stranded DNA genomes use a multigene strategy based on holins, small membrane proteins, and bacteriolytic enzymes, or endolysins. Holins mediate the control of endolysin activity and thus the timing of lysis. Phages with small genomes only encode a single protein for cell lysis. There are three known unrelated single protein lysis systems: the ?X174 E protein, the MS2 L protein, and the Q? A2 protein. None of these phages encodes a cell wall degrading activity, and previous work has shown that the lytic activity of E stems from its ability to inhibit the host enzyme, MraY, which catalyzes the formation of lipid I, the first lipid intermediate in cell wall synthesis. The purpose of the work described in this dissertation was to characterize the ?X174 E-mediated inhibition of MraY using genetic and biochemical strategies. A fundamental question was why no large phages use the single gene system. This was addressed by constructing a recombinant phage, ?E, in which the holin-endolysin based lysis cassette of ? was replaced with E. ?E was compared with ? in genetic and physiological experiments, with the results indicating that the holin-endolysin system increases fitness in terms of adjusting lysis timing to environmental conditions. Using ?E, physiological experiments were conducted to characterize the interaction between E and MraY in vivo. Transmembrane domains (TMD) 5 and 9 have been identified as the potential E binding site by isolating MraY mutants resistant to E inhibition. The five Eresistant MraY mutants were found to fall into three classes, which reflect the apparent affinity of the mutant proteins for E. Finally, an assay for MraY activity employing the dansylated UDP-MurNAc-pentapeptide and phytol-P, was used to demonstrate the inhibition of MraY by purified E protein. It was determined that E is a non-competitive inhibitor for MraY in respect with both substrates. A model for E-mediated inhibition of MraY was proposed, in which E binds to TMDs 5 and 9 in MraY and thus inactivates the enzyme by inducing a conformational change.
7

The Relative Effectiveness of Positive Interdependence and Group Processing on Student Achievement, Interaction, and Attitude in Online Cooperative Learning

Nam, Chang Woo 14 January 2010 (has links)
The purpose of this study was to investigate the relative effectiveness of positive interdependence and group processing on student achievement, interaction, and attitude in online cooperative learning. All of the participants, 144 college students enrolled in one of three different courses, received initial general instruction about teamwork skills and cooperative learning at the start of the study. Participants were then randomly assigned to one of three treatment groups: positive interdependence, group processing, and no structure. The ?positive interdependence? groups received subsequent positive interdependence skills training which were then utilized in their instructional activities. The ?group processing? groups received subsequent group processing skills training for use in their instructional activities. The ?no structure? groups received no additional instructional treatment beyond the initial basic teamwork and cooperative learning training. Results indicated that there were significant differences among students in the ?positive interdependence,? ?group processing,? and ?no structure? groups with respect to their achievement scores and interactions. Participants in the ?positive interdependence? groups had significantly higher achievement than participants in either the ?group processing? groups or the ?no structure? groups. In addition, participants in the ?positive interdependence? groups and the ?group processing? groups interacted with each other to a greater extent than those in the ?no structure? groups. This study also examined the relative effectiveness of positive interdependence and group processing on types of student interaction. The results indicated that ?positive interdependence? strategies were relatively more effective than ?group processing? strategies on ?sharing and comparing of information? interactions, whereas ?group processing? strategies were relatively more effective than ?positive interdependence? strategies on ?negotiation of meaning and co-construction of knowledge? interactions. Regarding student attitude towards the experiences of cooperative learning: participation, communication resources, and online activities, there was no significant difference among any of the three groups. The overall results of this study suggest that instructors would be advised to incorporate positive interdependence strategies in their online courses to help students perceive that they should actively contribute to their online group activities. In addition, instructors are recommended to inform groups of the individual progress of each member?s activities periodically by employing group processing strategies.
8

ESTABLISHING A VALID AND RELIABLE COMPETENCY ASSESSMENT FOR GYMNASTICS COACH CERTIFICATION

2014 August 1900 (has links)
Coaches in Canada are trained through the National Coaching Certification Program (NCCP) administered by The Coaching Association of Canada. The NCCP is the national standard and recently shifted its educational emphasis from the transfer of knowledge to the development of coaching competency. As a result, coaches are required to demonstrate competency in a specified sport and level prior to being awarded a coaching certification. The purpose of this study was to establish validity and reliability of an NCCP coaching competency assessment. Gymnastics Canada agreed to have their Community Sport coaching competency instrument tested for content validity, face validity, inter-rater reliability and intra-rater reliability. Their original assessment instrument was revised during content validity testing based on recommendations from five coaching context experts. Removing six items, adding one item, and revising four items for clarity modified the original 48-item instrument. An assessment of overall competency was added to the instrument to rate the coach as Beginner, Competent, Proficient, or Expert. Three certified coaches confirmed the face validity of the modified instrument. Reliability tests were conducted on the ratings provided by ten experts who observed a coach’s lesson on video. The result was a moderate level of inter-rater reliability, displayed by an Agreement Coefficient (AC1) of 0.43 and a Percent of Agreement (PA) of 72%. Nine of the ten raters assessed the coach’s performance as Competent, Proficient or Expert, while one of the ten rated the coach as Beginner. After a repeat observation of the same coaching performance, the intra-rater reliability of five raters resulted in agreement levels of Moderate (AC1 = 0.45; PA = 67%), Substantial (AC1 = 0.75, 0.77; PA = 81%, 89%), and Almost Perfect (AC1 = 0.87, 0.82; PA = 93%, 90%). The modified instrument has content and face validity. However, its usefulness is impacted by variability in rater preferences. The inter-rater reliability results attest to concerns about the consistency in assessment of a coaching certificate for Community Sport Artistic Gymnastics coaches. Suggestions to improve the reliability of the instrument include training raters to classify the coach’s competency on a standardized scale of sport-specific expertise.
9

THE EFFECTS OF ELECTRON BEAM IRRADIATION AND SANITIZERS IN THE REDUCTION OF PATHOGENS AND ATTACHMENT PREVENTION ON SPINACH

Neal, Jack A. 2009 May 1900 (has links)
The effects of electron beam (e-beam) irradiation and sanitizers in the reduction of Escherichia coli O157:H7 and Salmonella counts and attachment prevention on spinach was studied. Survival of these pathogens in spinach was observed at multiple times and temperatures. Inoculated spinach was examined by confocal microscopy to determine attachment sites and internalization of these pathogens. To determine the effectiveness of sanitizers in reducing pathogen numbers, inoculated spinach was treated with L-lactic acid, peroxyacetic acid, calcium hypochlorite, ozone, and chlorine dioxide. Inoculated spinach was exposed to e-beam irradiation and tested for counts of both pathogens immediately after irradiation treatment to determine bacterial reduction, and at 2 day intervals over 8 days to determine effects of ionizing irradiation on pathogen survival. Respiration rates were measured on spinach exposed to e-beam. The effectiveness of e-beam irradiation on the microbiological and sensory characteristics of spinach was studied. For spinach samples stored at 4�C and 10�C for 8 days, E. coli O157:H7 survived and grew significantly in samples stored at 21�C for 24 h. Confocal microscopy images provided valuable information on the attachment sites and internalization of the pathogens on spinach. The greatest reduction by a chemical sanitizer was 55�C L-lactic acid with a 2.7 log CFU/g reduction for E. coli O157:H7 and 2.3 log CFU/g reduction for Salmonella. Each dose of e-beam irradiation significantly reduced populations of both pathogens. Respiration rates of spinach increased as irradiation treatment doses increased. Total aerobic plate counts were reduced by 2.6 and 3.2 log CFU/g at 0.7 and 1.4 kGy, respectively. Lactic acid bacteria were reduced at both doses but grew slowly over the 35 day period. Yeasts and molds were not reduced in samples exposed to 0.7 kGy whereas 1.4 kGy had significantly reduced counts. Gas compositions for samples receiving 0.7 and 1.4 kGy were significantly different than controls. Irradiation did not affect the objective color or basic taste, aromatic or mouthfeel attributes of spinach. These results suggest that low dose e-beam irradiation may be a viable tool for reducing microbial populations or eliminating E. coli O157:H7 and Salmonella from spinach with minimal product damage.

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