894 resultados para Analysis of teaching process


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The primary goal of this dissertation is the study of patterns of viral evolution inferred from serially-sampled sequence data, i.e., sequence data obtained from strains isolated at consecutive time points from a single patient or host. RNA viral populations have an extremely high genetic variability, largely due to their astronomical population sizes within host systems, high replication rate, and short generation time. It is this aspect of their evolution that demands special attention and a different approach when studying the evolutionary relationships of serially-sampled sequence data. New methods that analyze serially-sampled data were developed shortly after a groundbreaking HIV-1 study of several patients from which viruses were isolated at recurring intervals over a period of 10 or more years. These methods assume a tree-like evolutionary model, while many RNA viruses have the capacity to exchange genetic material with one another using a process called recombination. ^ A genealogy involving recombination is best described by a network structure. A more general approach was implemented in a new computational tool, Sliding MinPD, one that is mindful of the sampling times of the input sequences and that reconstructs the viral evolutionary relationships in the form of a network structure with implicit representations of recombination events. The underlying network organization reveals unique patterns of viral evolution and could help explain the emergence of disease-associated mutants and drug-resistant strains, with implications for patient prognosis and treatment strategies. In order to comprehensively test the developed methods and to carry out comparison studies with other methods, synthetic data sets are critical. Therefore, appropriate sequence generators were also developed to simulate the evolution of serially-sampled recombinant viruses, new and more through evaluation criteria for recombination detection methods were established, and three major comparison studies were performed. The newly developed tools were also applied to "real" HIV-1 sequence data and it was shown that the results represented within an evolutionary network structure can be interpreted in biologically meaningful ways. ^

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This research focuses on the design and verification of inter-organizational controls. Instead of looking at a documentary procedure, which is the flow of documents and data among the parties, the research examines the underlying deontic purpose of the procedure, the so-called deontic process, and identifies control requirements to secure this purpose. The vision of the research is a formal theory for streamlining bureaucracy in business and government procedures. ^ Underpinning most inter-organizational procedures are deontic relations, which are about rights and obligations of the parties. When all parties trust each other, they are willing to fulfill their obligations and honor the counter parties’ rights; thus controls may not be needed. The challenge is in cases where trust may not be assumed. In these cases, the parties need to rely on explicit controls to reduce their exposure to the risk of opportunism. However, at present there is no analytic approach or technique to determine which controls are needed for a given contracting or governance situation. ^ The research proposes a formal method for deriving inter-organizational control requirements based on static analysis of deontic relations and dynamic analysis of deontic changes. The formal method will take a deontic process model of an inter-organizational transaction and certain domain knowledge as inputs to automatically generate control requirements that a documentary procedure needs to satisfy in order to limit fraud potentials. The deliverables of the research include a formal representation namely Deontic Petri Nets that combine multiple modal logics and Petri nets for modeling deontic processes, a set of control principles that represent an initial formal theory on the relationships between deontic processes and documentary procedures, and a working prototype that uses model checking technique to identify fraud potentials in a deontic process and generate control requirements to limit them. Fourteen scenarios of two well-known international payment procedures—cash in advance and documentary credit—have been used to test the prototype. The results showed that all control requirements stipulated in these procedures could be derived automatically.^

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This study explained the diversity of corporate financial practices in two nations. Existing studies have emphasized the reliance on equity finance in U.S. firms and bank loans in Japanese firms. In fact, patterns of corporate finance were much more complex. Financial institutions, which were created by national economic policy and regulation, affected corporate financial practices, but corporate financial practices often differed from what policymakers expected. Differences in corporate financial practices between nations also reflected differences in the mixture of industries in each nation. Many factors such as the amount of fixed capital, the process of production, the level of risk, the degree of innovation, and the importance of the industry in the national economy affected corporate financial practices. In addition, corporate financial practices within each nation differed from firm to firm due to managers’ considerations about stock ownership, which would affect their control power; corporate finance was closely related to control over management through ownership. To explain these complexities of corporate financial practices, the study linked corporate finance with the development of financial institutions in the United States and in Japan. While financial institutions affected corporate financial practices, the response of the firms to financial institutions and opportunities were diverse. The study also attempted to grasp variations in corporate financial practices by dealing with companies in three sectors: railroads, public utilities, and manufacturing. Finally, the study examined the structure of firm ownership. Contradictory to the widely held belief that U.S. firms distributed securities more widely to the public than did Japanese firms, many large American firms remained closely held, while some Japanese counterparts built publicly-held corporations.

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This study examined the feasibility of using a session impact measure with a sample of 24 at risk high school students participating in an intervention targeting identity and intimacy. Three therapists led 3 intervention groups with the same format. The study investigated the impact of therapy process, including Group, Facilitator, Skills, and Exploration impacts as measured by the Session Evaluation Form (SEF). The study also investigated the differential impact of session process on intervention outcome as measured by the CPSS, EPSI, RAVS, EIPQ and Youth Report Form. Analyses were conducted using descriptive statistics, frequencies, one-way analysis of variance (ANOVA), and Chi square tests. The results supported the utility of the SEF and they tentatively supported the impact of the therapist on participants' perceptions of therapeutic processes and on intervention outcome. In particular, Group 1 performed better than Group 3. This study found that the SEF is a useful session impact measure.

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This research focuses on the design and verification of inter-organizational controls. Instead of looking at a documentary procedure, which is the flow of documents and data among the parties, the research examines the underlying deontic purpose of the procedure, the so-called deontic process, and identifies control requirements to secure this purpose. The vision of the research is a formal theory for streamlining bureaucracy in business and government procedures. Underpinning most inter-organizational procedures are deontic relations, which are about rights and obligations of the parties. When all parties trust each other, they are willing to fulfill their obligations and honor the counter parties’ rights; thus controls may not be needed. The challenge is in cases where trust may not be assumed. In these cases, the parties need to rely on explicit controls to reduce their exposure to the risk of opportunism. However, at present there is no analytic approach or technique to determine which controls are needed for a given contracting or governance situation. The research proposes a formal method for deriving inter-organizational control requirements based on static analysis of deontic relations and dynamic analysis of deontic changes. The formal method will take a deontic process model of an inter-organizational transaction and certain domain knowledge as inputs to automatically generate control requirements that a documentary procedure needs to satisfy in order to limit fraud potentials. The deliverables of the research include a formal representation namely Deontic Petri Nets that combine multiple modal logics and Petri nets for modeling deontic processes, a set of control principles that represent an initial formal theory on the relationships between deontic processes and documentary procedures, and a working prototype that uses model checking technique to identify fraud potentials in a deontic process and generate control requirements to limit them. Fourteen scenarios of two well-known international payment procedures -- cash in advance and documentary credit -- have been used to test the prototype. The results showed that all control requirements stipulated in these procedures could be derived automatically.

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Parental involvement is an integral part of the educational system in the U.S. Yet, parents from non-mainstream racial/ethnic backgrounds have not fully grasped the nature of parental involvement expectations in the educational process and how these expectations may impact student achievement. The purpose of this study was to identify Haitian parents’ perceptions of their children with disabilities and the education these children were receiving. Several authors have conducted studies on parents of children with disabilities to better gain an understanding of the level of their involvement with their children’s education, their perceptions of the children, and their views on the school system (Harry, 1992a, 1992b). In this study, Haitian parents of children with disabilities were interviewed using an interview protocol. Through these interviews, this study explored 10 Haitian parents’ perceptions of their child with a disability, the education the child was receiving, their interaction with the school system, and how the disability had affected their relationship with their child and their involvement with the school. Findings of the present study revealed that these Haitian parents seldom disagreed with school personnel and did not seem to fully grasp the different methods available to address their concerns as parents of children with disabilities nor the role they were expected to play in the process. The majority did not have basic literacy skills in Creole or English. The parents in this study were overwhelmed by school written communication. Additionally, this study discovered that parents’ perceptions were guided by two core concepts: coping mechanisms and locus of control. Parents with an internal locus of control, who tended to be more educated, focused inward to find solutions to problems encountered. Those with an external locus of control relied on outside influences to resolve their problems. Parental involvement was strongly influenced by their values, beliefs, customs, and conceptual knowledge about disability; all closely aligned with culture and acculturation. Overall, these parents’ perceptions greatly influenced their thoughts and behaviors when they realized that their children with disabilities might fall short of their immigrant dreams of success they held for these children.

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One of the major problems in the analysis of beams with Moment of Inertia varying along their length, is to find the Fixed End Moments, Stiffness, and Carry-Over Factors. In order to determine Fixed End Moments, it is necessary to consider the non-prismatic member as integrated by a large number of small sections with constant Moment of Inertia, and to find the M/EI values for each individual section. This process takes a lot of time from Designers and Structural Engineers. The object of this thesis is to design a computer program to simplify this repetitive process, obtaining rapidly and effectively the Final Moments and Shears in continuous non-prismatic Beams. For this purpose the Column Analogy and the Moment Distribution Methods of Professor Hardy Cross have been utilized as the principles toward the methodical computer solutions. The program has been specifically designed to analyze continuous beams of a maximum of four spans of any length, integrated by symmetrical members with rectangular cross sections and with rectilinear variation of the Moment of Inertia. Any load or combination of uniform and concentrated loads must be considered. Finally sample problems will be solved with the new Computer Program and with traditional systems, to determine the accuracy and applicability of the Program.

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The primary purpose of this thesis was to present a theoretical large-signal analysis to study the power gain and efficiency of a microwave power amplifier for LS-band communications using software simulation. Power gain, efficiency, reliability, and stability are important characteristics in the power amplifier design process. These characteristics affect advance wireless systems, which require low-cost device amplification without sacrificing system performance. Large-signal modeling and input and output matching components are used for this thesis. Motorola's Electro Thermal LDMOS model is a new transistor model that includes self-heating affects and is capable of small-large signal simulations. It allows for most of the design considerations to be on stability, power gain, bandwidth, and DC requirements. The matching technique allows for the gain to be maximized at a specific target frequency. Calculations and simulations for the microwave power amplifier design were performed using Matlab and Microwave Office respectively. Microwave Office is the simulation software used in this thesis. The study demonstrated that Motorola's Electro Thermal LDMOS transistor in microwave power amplifier design process is a viable solution for common-source amplifier applications in high power base stations. The MET-LDMOS met the stability requirements for the specified frequency range without a stability-improvement model. The power gain of the amplifier circuit was improved through proper microwave matching design using input/output-matching techniques. The gain and efficiency of the amplifier improve approximately 4dB and 7.27% respectively. The gain value is roughly .89 dB higher than the maximum gain specified by the MRF21010 data sheet specifications. This work can lead to efficient modeling and development of high power LDMOS transistor implementations in commercial and industry applications.

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Thiosalt species are unstable, partially oxidized sulfur oxyanions formed in sulfur-rich environments but also during the flotation and milling of sulfidic minerals especially those containing pyrite (FeS₂) and pyrrhotite (Fe₍₁₋ₓ₎S, x = 0 to 0.2). Detecting and quantifying the major thiosalt species such as sulfate (SO₄²⁻), thiosulfate (S₂O₃²⁻), trithionate (S₃O₆²⁻), tetrathionate (S₄O₆²⁻) and higher polythionates (SₓO₆²⁻, where 3 ≤ x ≤ 10) in the milling process and in the treated tailings is important to understand how thiosalts are generated and provides insight into potential treatment. As these species are unstable, a fast and reliable analytical technique is required for their analysis. Three capillary zone electrophoresis (CZE) methods using indirect UV-vis detection were developed for the simultaneous separation and determination of five thiosalt anions: SO₄²⁻, S₂O₃²⁻, S₃O₆²⁻, S₄O₆²⁻ and S₅O₆²⁻. Both univariate and multivariate experimental design approaches were used to optimize the most critical factors (background electrolyte (BGE) and instrumental conditions) to achieve fast separation and quantitative analysis of the thiosalt species. The mathematically predicted responses for the multivariate experiments were in good agreement with the experimental results. Limits of detection (LODs) (S/N = 3) for the methods were between 0.09 and 0.34 μg/mL without a sample stacking technique and nearly four-fold increase in LODs with the application of field-amplified sample stacking. As direct analysis of thiosalts by mass spectrometry (MS) is limited by their low m/z values and detection in negative mode electrospray ionization (ESI), which is typically less sensitive than positive ESI, imidazolium-based (IP-L-Imid and IP-T-Imid) and phosphonium-based (IP-T-Phos) tricationic ion-pairing reagents were used to form stable high mass ions non-covalent +1 ion-pairs with these species for ESI-MS analysis and the association constants (Kassoc) determined for these ion-pairs. Kassoc values were between 6.85 × 10² M⁻¹ and 3.56 × 10⁵ M⁻¹ with the linear IP-L-Imid; 1.89 ×10³ M⁻¹ and 1.05 × 10⁵ M⁻¹ with the trigonal IP-T-Imid ion-pairs; and 7.51×10² M⁻¹ and 4.91× 10⁴ M⁻¹ with the trigonal IP-T-Phos ion-pairs. The highest formation constants were obtained for S₃O₆²⁻ and the imidazolium-based linear ion-pairing reagent (IP-L-Imid), whereas the lowest were for IP-L-Imid: SO₄²⁻ ion-pair.

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Acknowledgements This article is based on a doctoral research project of the first author which was sponsored by an international drilling rig operator. The views presented are those of the authors and should not be taken to represent the position or policy of the sponsor. The authors wish to thank the industrial supervisor and the drilling experts for their contribution and patience, as well as Aberdeen Drilling School for allowing the first author to attend one of their well control courses.

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This work studied the drying kinetics of the organic fractions of municipal solid waste (MSW) samples with different initial moisture contents and presented a new method for determination of drying kinetic parameters. A series of drying experiments at different temperatures were performed by using a thermogravimetric technique. Based on the modified Page drying model and the general pattern search method, a new drying kinetic method was developed using multiple isothermal drying curves simultaneously. The new method fitted the experimental data more accurately than the traditional method. Drying kinetic behaviors under extrapolated conditions were also predicted and validated. The new method indicated that the drying activation energies for the samples with initial moisture contents of 31.1 and 17.2 % on wet basis were 25.97 and 24.73 kJ mol−1. These results are useful for drying process simulation and industrial dryer design. This new method can be also applied to determine the drying parameters of other materials with high reliability.

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One commonality across the leadership and knowledge related literature is the apparent neglect of the leaders own knowledge. This thesis sought to address this issue through conducting exploratory research into the content of leader’s personal knowledge and the process of knowing it. The empirical inquiry adopted a longitudinal approach, with interviews conducted at two separate time periods with an extended time-interval between each. The findings from this research contrast with images of leadership which suggest leaders are in control of what they know, that they own their own knowledge. The picture that emerges is one of individuals struggling to keep abreast of the knowledge required to deal with the dynamics and uncertainties of organisational life. Much knowledge is tacit, provisional and perishable and the related process of knowing more organic, evolutionary and informal than any structured or orchestrated approach. The collective nature of knowing is a central feature, with these leaders embedded in networks of uncontrollable relationships. In view of the indeterminate nature of knowing, the boundary between what is known and what one needs to know is both amorphous and ephemeral, and the likelihood of knowledge-absences is escalated. A significant finding in this regard is the identification of two critical points where not-knowing is most likely (entry and exit from role) and the differing implications of each. Overtime the knowledge that is legitimised or prioritised is significantly altered as these leaders replace the dogmas that were previously held in high esteem with the lessons from their own experience. This experience brings increased self-knowledge and a deeper appreciation of the values and morals instilled in their early lives. In view of the above findings, this study makes theoretical contribution to a number of core literatures: authentic leadership, role transition and knowledge-absences. In terms of leadership development, the findings point to the necessity to prepare leaders for the challenges they will encounter at the pivotal stages of the leadership role.

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Olfactory sensory neurons (OSNs), which detect a myriad of odorants, are known to express one allele of one olfactory receptor (OR) gene (Olfr) from the largest gene family in the mammalian genome. The OSNs expressing the same OR project their axons to the main olfactory bulb where they converge to form glomeruli. This “One neuron-one receptor rule” makes the olfactory epithelium (OE), which consists of a vast number of OSNs expressing unique ORs, one of the most heterogeneous cell populations. However, the mechanism of how the single OR allele is chosen remains unclear along with the question of whether one OSN only expresses a single OR gene, a hypothesis that has not been rigorously verified while we performed the experiments. Moreover, failure of axonal targeting to single glomerulus was observed in MeCP2 deficient OSNs where delayed development was proposed as an explanation for the phenotype. How Mecp2 mutation caused this aberrant targeting is not entirely understood.

In this dissertation, we explored the transcriptomes of single and mature OSNs by single-cell RNA-Seq to reveal their heterogeneity and further studied the OR gene expression from these isolated OSNs. The singularity of sequenced OSNs was ensured by the observation of monoallelic expression of X-linked genes from the hybrid samples from crosses between mice of different strains where strain-specific polymorphisms could be used to track the allelic origins of SNP-containing reads. The clustering of expression profiles from triplicates that originated from the same cell assured that the transcriptomic identities of OSNs were maintained through the experimental process. The average gene expression profiles of sequenced OSNs correlated well to the conventional transcriptome data of FACS-sorted Omp-positive cells, and the top-ranked expression of OR was conceded in the single-OSN transcriptomes. While exploring cellular diversity, in addition to OR genes, we revealed nearly 200 differentially expressed genes among the sequenced OSNs in this study. Among the 36 sequenced OSNs, eight cells (22.2%) showed multiple OR gene expression and the presences of additional ORs were not restricted to the neighbor loci that shared the transcriptional effect of the primary OR expression, suggesting that the “One neuron-one receptor rule” might not be strictly true at the transcription level. All of the inferable ORs, including additional co-expressed ORs, were shown to be monoallelic. Our sequencing of 21 Mecp2308 mutant OSNs, of which 62% expressed more than one OR genes, and the expression levels of the additional ORs were significantly higher than those in the wild-type, suggested that MeCP2 plays a role in the regulation of singular OR gene expression. Dual label in situ hybridization along with the sequence data revealed that dorsal and ventral ORs were co-expressed in the same Mecp2 mutant OSN, further implying that MeCP2 might be involved in regulation of OR territories in the OE. Our results suggested a new role of MeCP2 in OR gene choice and ratified that this multiple-OR expression caused by Mecp2 mutation did not accompany delayed OSN development that has been observed in the previous studies on the Mecp2 mutants.