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The objective of this dissertation study is to provide the theoretical foundation for collaborative information technology moderation on team performance and give empirical evidence to support this relationship. The model provided in this study is supported by analytical proofs for the proposed hypotheses to define relationships among constructs in this research including departure (reduction in the number of team members), collaborative information technology functionality, transactive memory strength, and team performance. This research offers a theory that utilizes transactive memory systems (TMS) to examine the departure problem. The main research question is: Can collaborative information technologies (CIT) alleviate negative effects of departure? The theory in this study is structured around the indicators of TMS: specialization, coordination, and credibility. Findings showed that CIT functionality level plays a role in enhancing the group performance. This role is not direct but instead, is a moderation effect that alleviates the negative departure impact. In absence of departure, CIT impact can be confusing as it can be either positive or negative. My analytical results explain why information systems literature has had conflicting arguments on the role of technology. I propose that particular dynamic events and incidents, such as employee departure, help us understand the impact of CIT more clearly. Moreover, I employ transactive memory theory to explain how individuals develop and exchange knowledge in a group and how skills and knowledge can be lost due to departure. I also explain why and how team performance benefits from CIT when departure occurs. / text

<p>Travel demand management policies such as congestion charges encourage car-users to change among other things route, mode and departure time. Departure time may be especially affected by time-varying charges, since car-users can avoid high peak hour charges by travelling earlier or later, so called peak spreading effects. Conventional transport models do not include departure time choice as a response. For evaluation of time-varying congestion charges departure time choice is essential.</p><p>In this thesis a transport model called SILVESTER is implemented for Stockholm. It includes departure time, mode and route choice. Morning trips, commuting as well as other trips, are modelled and time is discretized into fifteen-minute time periods. This way peak spreading effects can be analysed. The implementation is made around an existing route choice model called CONTRAM, for which a Stockholm network already exists. The CONTRAM network has been in use for a long time in Stockholm and an origin-destination matrix calibrated against local traffic counts and travel times guarantee local credibility. On the demand side, an earlier developed departure time and mode choice model of mixed logit type is used. It was estimated on CONTRAM travel times to be consistent with the route choice model. The behavioural response under time-varying congestion charges was estimated from a hypothetical study conducted in Stockholm.</p><p>Paper I describes the implementation of SILVESTER. The paper shows model structure, how model run time was reduced and tests of convergence. As regards run time, a 75% cut down was achieved by reducing the number of origin-destination pairs while not changing travel time and distance distributions too much.</p><p>In Paper II car-users underlying preferred departure times are derived using a method called reverse engineering. This method derives preferred departure times that reproduce as well as possible the observed travel pattern of the base year. Reverse engineering has previously only been used on small example road networks. Paper II shows that application of reverse engineering to a real-life road network is possible and gives reasonable results.</p> / Silvester

There remains limited research on the gap between the participation and persistence to graduation rates for American Indian students in higher education. It is pertinent to explore the experiences of these students who did not persist to graduation to be able to gain a better understanding of the factors involved in this gap. The primary purpose of this qualitative study was to gain a greater understanding of why twenty American Indian college students who were high-achieving and received the Gates Millennium scholarship (AIGMS) did not persist to graduation. To achieve this greater understanding from an Indigenous perspective, it was important to utilize existing theoretical frameworks developed by Native scholars that employed critical, culturally sensitive lenses for the analysis. Through the lenses of Tribal Critical Race Theory, Cultural Models of Education and the Family Education Model, the research questions were developed with a critical focus on the institutional influence of the participants' experiences. This study employed a phenomenological qualitative approach guided by an Indigenous research paradigm. The findings of this research inquiry were broken down into five main sections. The first section discussed the pre-collegiate experiences of AIGMS. This set of findings emerged throughout the interviews as participants shared their experiences in college, they often referred back to influential moments with their families and tribal communities leading up to college. The second section highlighted the conditions that impeded AIGMS' success in institutions of higher education. What emerged as the major factors of AIGMS' non persistence within higher education was GMSP's inflexible deferment policy and missing structures on campus to represent participants’ Native and Gates scholar identities, such as space for AIGMS to practice their cultural spirituality and direct support on campus for being a Gates scholar. The third section reveals the push-pull factors influential to AIGMS' experiences on campus and back home in their tribal communities. The main push factor from the institution was the lack of support they felt from key institutional agents, such as from a multicultural center director, financial aid officer or academic advisor. The fourth section describes the impact of the campus racial climate on AIGMS' experiences on their respective campuses. Some AIGMS assumed that being awarded this prestigious scholarship would be acknowledged either through their faculty or staff on campus. Instead they described examples of exclusion, lack of belonging, marginalization, isolation and invisibility on campus. The final section described the experiences of AIGMS who returned to higher education, including those who have found success in tribal colleges as well as those who have since completed their degrees without funding from GSMP. This finding is of particular importance because it demonstrates that the loss of financial aid affected the type of institution AIGMS' returned. Principally, AIGMS were thoughtful and rational about their decision to defer from higher education, taking into account the factors pulling them from outside the institution – such as family/medical/health issues. They were also impacted by their experiences within their institutions that pushed them out from within – such as experiences with invisibility and marginalization on campus. Faculty, institutional agents and their peers played into these experiences. The Gates Millennium Scholarship Program and institutions’ lack of cultural understanding of how to serve these AIGMS led to a disconnection with these students. These AIGMS’ experiences with push and pull factors places more responsibility on the institution and the scholarship program for their non-persistence.

Using Tinto's longitudinal model of institutional departure as the theoretical basis for this research, the purpose was to determine what extent selected motivational factors measured by the College Student Inventory (CSI) predict academic success and persistence of at-risk students at the University of North Texas (UNT). The study focused on United States citizens and permanent residents entering UNT as at-risk first-time freshmen admitted via individual approval for the fall 1994 semester. The 409 subjects were enrolled in a developmental course titled Personal and Academic Effectiveness where the CSI was administered during the first 2 weeks of class. Selected predictor variables were tested in relation to the separate criterion variables of grade point average and enrolled status during the 2nd and 4th years of the study. Grade point averages and enrollment data for the 1995-96 and 1997-98 academic years were extracted from the student information management system. The research design employed appropriate multiple regressions, multiple correlations, multiple discriminant analyses, and bivariate correlations. Findings confirmed the ability of five CSI factors to predict grade point average (p < .05) of at-risk students over the time frames used in this study. Nine factors predicting enrolled status were also significant at the .05 level; however, results were not meaningful in the 2nd year as factors classified 95% of all subjects as persisters. By the end of the 4th year, the factors were able to predict correct classification of both persisters and nonpersisters approximately 24% better than chance. This research provides support for Tinto's institutional departure model, particularly associated with pre-entry attributes and goals/commitments over time. The CSI is a viable instrument for use with at-risk first-time freshmen at a metropolitan university; however, required enrollment in a developmental course likely confounded the ability of selected variables to meaningfully predict enrolled status during the 2nd year.

Master of Science / Department of Clinical Sciences / Daniel U. Thomson / Bovine respiratory disease (BRDC) is a multifaceted disease that causes considerable economic loss in both the beef and dairy industry. However, because there may be lingering effects of BRDC in the dairy industry, the full economic costs of the disease may not be realized. These lingering effects may include an increased departure from the herd, decreased milk production, and decreased reproductive performance. All of these outcomes are affected by multiple variables, but proper statistical modeling can control for many of the different influences. Few studies have attempted to look at the long term effects of calfhood BRDC but consistent associations have not been identified. The objective of this observational, retrospective study was to determine the association between calfhood BRDC prior to 120 d of age and departure from the herd, milk production, and reproductive performance. The association between the occurrence of BRDC with departure from the herd prior to first calving depended on the birth year, but for 5 of the 6 years, animals that contracted BRDC were 1.62 to 4.98 times more likely to leave the herd than animals that did not contract BRDC. In addition, animals that contracted BRDC were also 1.28 times more likely to leave the herd between first and second calving than animals that did not contract BRDC. Furthermore, the age at BRDC occurrence was associated with departure from the herd. Animals that contracted BRDC pre-weaning were 2.62 times more likely to leave the herd prior to first calving than animals that contracted BRDC post-weaning. However, age of BRDC occurrence was not significantly associated with departure from the herd between first and second calving. The occurrence of BRDC during the first 120 d of life was associated with a 233 kg decrease in lactation-one production, but was not significantly associated with production in subsequent lactations. Finally, calfhood BRDC was not significantly associated with a decreased reproductive performance measured by calving interval. In conclusion, calfhood BRDC negatively impacts productivity both prior to and after first calving.

This thesis presents an overall picture of demographic and socio-economic characteristics as well as journey to work travel behavior characteristics in Florida. In addition, detailed comparisons of journey to work private vehicle occupancy distribution, travel time distribution, mode choice and departure time distribution by household and individual characteristics are also provided based on three data files: American Community Survey Public Use Microdata Samples data file, Summary File 3 Public Use Microdata Samples 1% and Public Use Microdata Samples 5% data files. Utilizing the three data files, this thesis not only investigates current commuting patterns but also provides more reliable information on current journey to work characteristics and helps to gain knowledge that is useful to identify problems and provide creative solutions on related transportation issues in the state of Florida. In analyzing the data, several socio-economic and journey to work travel behavior characteristics were identified. Interesting findings include the lower utilization of transit, the lower private vehicle occupancies for individuals in Florida, and different journey to work departure time distribution by gender, by young people and by senior citizens from other adult categories. The data analysis shows that the three data files reflect acknowledged demographic trends and capture known changes such as aging of population, smaller household size, and increasing car ownership. The comparison analysis shows that in most cases, ACS PUMS data files approximate SF3 PUMS 1% and 5% data files very well. The detailed comparison of the three data files regarding journey to work travel behavior characteristics in Florida is important to decision makers who will make informed choices when evaluating alternative transportation programs and related policy issues. The knowledge of reliability of data regarding journey to work travel behavior will also help transportation professionals for travel demand modeling, transportation and land use planning and related studies.

Incoming first year students have varying expectations for their college experience. As Florida public education budgets are more closely aligned with student persistence and graduation rates, it is vital institutions retain more first time in college students. The purpose of this study was to better understand how first year student college expectations on academic preparation, co-curricular involvement, socializing, and institutional commitment relate to persistence into the second year of college at one of Florida’s large, preeminent public research universities. This quantitative study utilized the Beginning College Survey of Student Engagement (BCSSE) in order to better understand incoming student expectations. The study sample consisted of 3,723 first time in college students and was collected during orientation for the summer and fall 2015 cohort. Tinto’s Model of Student Departure (1975b), which served as the theoretical framework, states a student’s individual characteristics he/she possess when starting college influence his/her persistence as well as initial commitment to the institution and ultimately a degree. Logistic regression was used to determine the strength of the relationship between students’ expectations and persistence into the second year of college. The overall findings of this study contribute to the increased understanding of first year student expectations and help administrators understand how to best support students. The findings illustrate a statistically significant relationship between high school GPA and persistence into the second year. Expected involvement in organized campus co-curricular activities, self-perception of academic preparation, and a first year student’s commitment to the institution were not found to be statistically significant to first year student persistence into the second year. Additional key findings and their implications for practice in higher education are presented along with recommendations for future research.

Departure punctuality has increasingly gained attention over the last few years. This development is due to the realization what important role this issue plays in the economics of the airline industry. Punctuality is not just a sound performance indicator but also allows airlines to differentiate themselves from their competitors. In addition the issue holds a significant potential for cost savings. For this reason many airlines have started special programmes to improve their punctuality performance, and so did Lufthansa. However, despite this increasing attention, outbound punctuality levels have not yet reached satisfactory levels. Therefore, this study aimed at contributing to this process by identifying potential ontime performance improvements at the Lufthansa station at Frankfurt Airport. As an underlying framework, a Human Factors approach was chosen. Central issues in the focus of the study were the individual perceptions and attitudes towards punctuality by the relevant front line staff. In order to examine these issues a survey among the Flight Managers, Assistant Flight Managers, and Section leaders was carried out. The results of this survey were then put into correlation with the delay statistics published. The results of the survey indicate a potential lack of communication among the front line staff as well as between them and higher organizational entities. Moreover, certain distrust towards the delay statistics became evident. Although the staff members seem quite well motivated, they feel a lack of commitment by their superiors. In addition, the survey gathered some interesting ideas for punctuality improvements held by the front line staff members. Besides very concrete topics for discussion, the central outcome of the study was the recommendation to analyze all relevant processes at the Lufthansa station from a Human Factors perspective in order to improve the communicative situation. Moreover, the study suggests introducing appropriate incentive schemes in order to promote better on-time performance. Altogether these should result in a noticeable improvement of the punctuality situation at the Lufthansa station.

A MAP/PH/1 queue is a queue having a Markov arrival process (MAP), and a single server with phase-type (PH -type) distributed service time. This thesis considers the departure process from these type of queues. We use matrix analytic methods, the Jordan canonical form of matrices, non-linear filtering and approximation techniques. The departure process of a queue is important in the analysis of networks of queues, as it may be the arrival process to another queue in the network. If a simple description were to exist for a departure process, the analysis of at least feed-forward networks of these queues would then be analytically tractable. Chapter 1 is an introduction to some of the literature and ideas surrounding the departure process from MAP/PH/1 queues. Chapter 2 sets up the basic notation and establishes some results which are used throughout the thesis. It contains a preliminary consideration of PH -type distributions, PH -renewal processes, MAP s, MAP/PH/1 queues, non-linear filtering and the Jordan canonical form. Chapter 3 is an expansion of "The Output process of an MMPP/M/1 queue", where the question of whether a MAP description can exist for the departure process of a non-trivial MAP/M/1 queue is considered. In a 1994 paper, Olivier and Walrand conjectured that the departure process of a MAP/PH/1 queue is not a MAP unless the queue is a stationary M/M/1 queue. This conjecture was prompted by their claim that the departure process of an MMPP/M/1 queue is not MAP unless the queue is a stationary M/M/1 queue. We show that their proof has an algebraic error, which leaves open the above question of whether the departure process of an MMPP/PH/1 queue is a MAP or not. In Chapter 4, the more fundamental problem of identifying stationary M/M/1 queues in the class of MAP/PH/1 queues is considered. It is essential to be able to determine from its generator when a stationary MAP is a Poisson process. This does not appear to have been discussed in the literature prior to the author's paper, where this deficiency was remedied using ideas from non-linear filtering theory, to give a characterisation as to when a stationary MAP is a Poisson process. Chapter 4 expands upon "When is a MAP Poisson". This investigation of higher order representations of the Poisson process is motivated by first considering when a higher order PH -type distribution is just negative exponential. In Chapter 5, we consider the related question of minimal order representations for PH -type distributions, an issue which has attracted much interest in the literature. A discussion of other authors' ideas is given and these ideas are then inter-related to the work presented in Chapter 4 on the PH -type distributions. The MAP/M/1 queue is then considered in Chapter 6 from the perspective of whether having an exact level and phase independent stationary distribution of the geometric form [Formula - Not available: see pdf version of the abstract] implies that the MAP is Poisson. The answer is in the affirmative for this question, but the converse is not strictly true. Apart from showing the ubiquitous asymptotic form of level and phase independence exhibited by all stable MAP/M/1 queues, we prove that a very large class of stable queues, exhibits what we have termed shift-one level and phase independence. Stable MAP/M/1 queues exhibiting shift-one level and phase independence, are characterised by a stationary distribution of the following form: [Formula - Not Available: see pdf version of the abstract] In Chapter 7, a family of approximations is proposed for the output process of a stationary MAP/PH/1 queue. To check the viability of these approximations, they are used as input to another single server queue. Performance measures for the second server are obtained analytically in both the tandem and approximation cases, thus eliminating the need for simulation to compare results. Comparison of these approximations is also made against other approximation methods in the literature. In Chapter 8, we show that our approximations from Chapter 7 have the property of exactly matching the inter-departure time distribution. Our kth approximation also accurately captures the first k-1 lag-correlation coefficients of the stationary departure process. The proofs of this direct association between lag-correlation coefficients and the level of complexity k are given. / Thesis (Ph.D.)--School of Applied Mathematics, 1999.