Dissertationen zum Thema „Four levels of feedback“

Thesis (D. Ed.)--University of Oregon, 2006.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 111-116). Also available for download via the World Wide Web; free to University of Oregon users.

Digital teaching materials are today considered an important complement in the teaching of mathematics in today's school. As our society becomes increasingly digital, it is even more important that the school adapts and develops its knowledge in digital curricula. That teachers then have knowledge of how these teaching aids are structured and work is now even more important, partly so they know which teaching aid is most effective both for the student's knowledge and development and as an aid to the teacher's ability to assess. In this work, a qualitative content analysis of five digital teaching materials in mathematics has been done. The purpose of the content analysis was to see which digital teaching materials have feedback as part of their offer and whether the teacher has the opportunity to provide feedback to the students in the digital teaching materials in mathematics for grades 1-3. All the digital teaching materials have been analyzed based on the student's and teacher's insight into the teaching materials, this was done with the help of an analysis schedule. The results have then been set against different levels of feedback to conclude that all five digital teaching aids have feedback at the task level as an important aspect. Furthermore, the analysis showed that there are three "types" of e-textbooks. One of the digital teaching materials examined belonged to one "type" of e-textbook while the other four belonged to one and the same. Finally, it could be stated that all five digital teaching aids have some shortcomings when it comes to feedback.
Digitala läromedel anses idag vara ett viktigt komplement i undervisningen inom matematik i dagens skola. Då vårt samhälle blir allt mer digitaliserat är det ännu viktigare att skolan anpassar sig och utvecklar sina kunskaper inom digitala verktyg. Att lärare då har kunskap om hur dessa läromedel är uppbyggda och fungerar är nu ännu viktigare, dels för att de ska veta vilket läromedel som är mest effektivt både före elevens kunskapsutveckling och som hjälpmedel för lärarens möjlighet till bedömning. I detta arbete har en kvalitativ innehållsanalys av fem digitala läromedel inom matematik gjorts. Syftet med innehållsanalysen var att se vilka digitala läromedel som har återkoppling som en del av sitt utbud samt om läraren har möjlighet till att ge återkoppling till eleverna via de digitala läromedlen i matematik för år 1–3. Alla de digitala läromedlen har analyserats utifrån elevens och lärarens insyn i dem, detta gjordes med hjälp av ett analysschema. Resultatet har sedan ställts emot olika nivåer av återkoppling för att komma fram till att alla de fem digitala läromedlen har återkoppling på uppgiftsnivå som en viktig aspekt. Vidare visade analysen att det finns tre ”typer” av e-läroböcker, det vill säga digitala läromedel. Ett av dem som undersöktes tillhörde en ”typ” av e-lärobok medan de andra fyra tillhörde ett annat digitalt läromedel. Slutligen kunde det konstateras att alla de digitala läromedel som undersöktes har några brister när det kommer till återkoppling.

Simulação computacional de ambientes cirúrgicos têm sido amplamente utilizados, normalmente para treinamentos, ajudando no desenvolvimento de habilidades essenciais e minimizando erros em procedimentos cirúrgicos. Para estes ambientes, é essencial a obtenção de um comportamento mais realista, sendo importante o uso de técnicas com alta precisão, além de uma simulação em tempo real. A fim de melhor controlar este trade-off entre eficiência e eficácia, apresentamos um ambiente híbrido e adaptativo que combina um conjunto de métodos para alcançar uma boa precisão e desempenho na simulação. Nosso sistema mescla métodos físicos de deformação (Método de Elementos Finitos e Mass-Mola) com um método não-físico que aproxima o comportamento dos primeiros (Green Coordinates), sendo capaz de utilizar o método apropriado dependendo da situação. Para melhor simular um ambiente cirúrgico completo, foram implementadas ferramentas adicionais para interação, permitindo pegar e manipular, queimar, e sentir os objetos do cenário. Nosso sistema proporciona grande imersão ao usuário, consumindo menos recursos computacionais e aumentando as taxas de atualização da simulação.
Computational simulation of surgical environments have been widely used usually for trainings, improving essential skills and minimizing errors in surgical procedures. As these environments are always looking for a more realistic behavior, it is important to use high-precision techniques while ensuring a real-time simulation. In order to better manage this trade-off between efficiency and effectiveness, we present a hybrid and adaptive environment that combines a set of methods to achieve good accuracy and performance for a simulation. Our system merges physically deformation methods (Finite Elements Method and Mass Spring Damper) with a non-physical method that approximates the formers behavior (Green Coordinates), being able to use the appropriate method depending on the situation. To simulate an approximation of a complete surgical environment, we also implement interaction tools, such as picking, burning, and haptic feedback. Our system provides great immersion for the user, consuming less computational resources and increasing update rates.

The most powerful influence on student achievement is the classroom teacher and the most effective instructional strategy teachers can use to increase student learning and achievement is effective feedback (Hattie & Timperley, 2007). The research on teacher feedback in kindergarten classrooms is scarce therefore this study helps reduce the void in the literature on the importance of teacher feedback in kindergarten classrooms. The purpose of this study was to examine effective teachers’ perceptions of the amount and kind of feedback they provide to their students and to determine if their perceptions match the feedback they actually provide. The participants in the study were four teachers from a public elementary school in middle Tennessee. Each teacher received the rating of effective teacher according to their 2015-2016 state-wide teacher evaluation. This study is based upon Lev Vygotsky’s sociocultural theory which proclaims student learning can be increased when teachers provide the necessary support to complete a task at a level higher than their current level of functioning. Teacher feedback is an effective and efficient instructional strategy to bridge the gap between students’ actual level of understanding and the level required to become independently successful. It is important, therefore that teachers become knowledgeable of feedback that will encourage rather than discourage independent learning. The qualitative design of this study included observing and analyzing teacher feedback during whole group instruction in kindergarten classrooms. The researcher collected data on four observed levels of teacher feedback: feedback about the task, feedback about the process, feedback about self-regulation and personal feedback about the self. Teachers’ perceptions of the kinds of feedback they provide most frequently did not match observed levels of feedback. The participants perceived themselves to provide more feedback about the process and self-regulation which are the most effective levels of feedback to increase student achievement. Their perceptions did not match observed levels of feedback provided to their students. The results of this study may be used as a catalyst for districts to provide professional development to instruct teachers how to effectively use the four levels of teacher feedback to increase student academic progress.

Twenty six male and two female participants in the Cardiac Therapy Program at Virginia Tech were stratified, based upon level of total cholesterol (TC) and length of time in the Cardiac Program, and then randomly assigned to either experimental or control groups. Participants ranged in age from 43 to 68 years and all had baseline TC levels greater than 200 mg/dl. There were no significant differences between groups in terms of baseline TC (control M : 248 mg/dl; experimental M = 251 mg/dl), blood pressure (BP), weight, predicted percent body fat, dietary fat/cholesterol, age, education, or program attendance.
Master of Science

This study examines teachers’ beliefs and practices of feedback in their writing classrooms, focusing particularly on the factors that shape these beliefs and practices. It also investigates junior and senior students’ preferences for feedback and their problems and strategies for handling feedback. It explores students’ reasons for their preferences. Further, it diagnoses the impact of students’ experience on their preferences, problems and strategies. It identifies the matches and mismatches between preferences of students and teachers’ practices. To achieve these objectives, junior and senior students’ data from questionnaire and interview were integrated, and teachers’ data from questionnaire, interview and analysis of teachers’ written feedback were triangulated. The findings suggest that not all teachers’ beliefs about feedback are translated into their practices. The factors shape teachers’ beliefs and practices are contextual factors (time allocated to writing classes, classroom size and availability of resources), teacher factors (teachers’ experiences with feedback as teachers and as student, teachers’ knowledge and their training) and student factors (students’ level of proficiency and students’ needs and preferences). The teachers’ ways of providing feedback are also guided by several pedagogical reasons (e.g. securing students’ understanding of feedback, prompting students’ engagement with feedback, meeting students’ needs). The results also reveal that the students seem to value feedback on their writing. However, there are some differences between junior and senior students’ preferences for the different aspects of feedback and differences between their difficulties and strategies for handling feedback. These results indicate that students’ experience has an impact on their preferences and ability to deal with feedback. Junior students seem to be more dependent on their teachers and classmates than senior students are. The findings also identify some differences between teachers’ practices and students’ views. This suggests that teachers’ practices may not always influence students’ preferences. These findings imply that feedback might be more effective if teachers consider their context of teaching, students’ experience, students’ proficiency level and needs. They also need to work cooperatively for extending their knowledge about feedback and developing their ways of providing feedback. The educational authorities need to offer information resources and training opportunities to enhance teachers’ professional development in responding to students’ writing effectively.

Thesis (Ed.D.)--Indiana University, Dept. of Instructional Systems Technology, 2008.
Title from home page (viewed on Jul 28, 2009). Source: Dissertation Abstracts International, Volume: 69-12, Section: A, page: 4693.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
A pesquisa objetivou testar raÃÃes (50% concentrado e 50% volumoso), utilizando diferentes nÃveis de substituiÃÃo de milho por resÃduo de panificaÃÃo. Foram utilizados 16 ovinos machos, sem raÃa definida, com peso vivo entre 18,5 e 26,5 kg. O perÃodo experimental teve duraÃÃo de 21 dias, sendo 14 dias para adaptaÃÃo e 7 dias para coleta de amostras. O delineamento experimental utilizado foi inteiramente casualizado com 4 tratamentos (substituiÃÃo de 20,0;40,0;60,0 e 80,0% do milho por resÃduo de panificaÃÃo), cada um com 4 repetiÃÃes. NÃo foram observadas diferenÃas significativas entre os tratamentos para os parÃmetros: digestibilidade de matÃria seca, proteÃna bruta, matÃria orgÃnica, extrato etÃreo, energia bruta, fibra em detergente neutro, ao nÃvel de 5% de probabilidade pelo teste de Tukey. O resÃduo de panificaÃÃo pode ser utilizado em atà 80% de substituiÃÃo ao milho em raÃÃes para ovinos em fase de terminaÃÃo, sendo a relaÃÃo volumoso: concentrado de 50:50.
The research objectified to test rations, (50% concentrate and 50% forrage), utilize different levels of substituition of corn for waste bakery (WB), in the concentrate.16 males sheeps were used without defined race and weigtht live between 18,5 and 26,5 kg. The experimental period had duration of 21 days, being 14 days for adptation and 7 days for collections of samples. The used experimental delineament was it entirely casuality with 4 treatments (levels of substituition of corn for remainder bakery in the concentrate 20,0;40,0;60,0 e 80,0%), each one with 4 repetitions. Significant differences were not observed among the treatments in the appraised produtive parameters ( it test of Tukey P>0,05), digestibility of dry matter (DM), crude protein (CP), organic matter (OM), ether extract (E.E), gross energy (GE), fyber on neutral detergent (FND). The remainder of bakery can be utilize in 80% of substituition the corn in rations to sheeps in the stage of termination, each the relacion forrage: concentrate of 50:50.

This study explored the comparison of microlab discussions of interpersonal competencies and corrective feedback on counselor trainees' defensiveness levels. Additionally, the effects of microlab discussions of interpersonal competencies or corrective feedback on counselor trainees' beliefs about their ability to communicate more clearly, receive corrective feedback with less difficulty, and act on corrective feedback receive more easily were explored. Participants in this study (N = 72) were counselor trainees enrolled in three different universities within the New Orleans metropolitan area. Participants completed the Tennessee Self-Concept Scale: Second Edition (TSCS: 2; Fitts & Warren, 1996) at least three weeks before taking part in a microlab discussion of interpersonal competencies or corrective feedback or not taking part in any discussion. Upon completion of the microlab discussion, participants in the treatment conditions completed the TSCS: 2 for the second time. Participants in the control condition simply met and completed the second administration of the TSCS: 2. Analyses of covariance were conducted on the posttest scores using the pretest as a covariate. Also, interaction effects were explored between demographic characteristics and treatment condition on posttest scores as well as responses to a group evaluation. Results did not support any of the hypotheses associated with participants who engaged in microlab discussion would have a lower defensiveness score as compared to a control group. Promising findings resulted from reactions to both microlabs by participants regarding their beliefs about their abilities to communicate more clearly, receive corrective feedback with less difficulty, and act on corrective feedback received more easily in the future. Also, a pattern associated with the number of courses completed was indicated due to a significant correlation with change in defensiveness course and interaction effects with treatment condition on responses to question 1 and 3 of the group evaluation. Counselor education programs, counselors who work with groups, and counselor trainees may benefit from exploring the possible benefits associated with microlab discussions as a form of pregroup training. Future research may provide more insight into the development of an instrument to more effectively measure defensiveness within the context of receiving corrective feedback. Also, the development of multi-session pregroup training may prove to be more effective in reducing defensiveness levels.

This study investigated the impact of working with domestic violence victims on domestic violence shelter workers. Recent research has shown that working with trauma victims may have a profound impact on the worker, including levels of intrusive and avoidant PTSD symptoms as well as distorted beliefs about the self and others. This was the first study to examine secondary traumatization in the domestic violence worker population. Results suggested that domestic violence workers are experiencing levels of secondary traumatization slightly higher than sexual assault counselors, a group used for comparison due to their similar job demands and client population. Though this study attempted to ameliorate symptom levels by providing feedback, and feedback with suggestions for improvement to two treatment groups, no significant effects were found post-treatment. Various reasons were offered for this lack of effect, including the lack of adequate sample size at follow-up. Overall, several predictors of secondary traumatization were confirmed, the most notable of which was social support. Individuals with high levels of social support tended to have less symptoms of secondary traumatization, and individuals with high levels of social avoidance tended to have more symptoms of secondary traumatization. For this sample, trauma history was not found to predict secondary traumatization symptoms. These findings were discussed in relation to the vicarious traumatization model of indirect trauma. Clinical implications and implications for future research were also offered. This study was supported in full by the Agency for Healthy Care Policy and Research Grant for Health Service Dissertation Award, number R03 HS10036-01.
Ph. D.

Theories of high commitment management (HCM) ascribe a central role to high trust relationships between management and labour if organisations are to achieve high performance (Legge, 2005; Appelbaum et al, 2000). However, such relations are difficult to achieve within the capitalist employment relationship, particularly so within liberal market economies such as the UK (Godard, 2002; Hall and Soskice, 2001). Employee involvement (EI) and participation initiatives potentially constitute a principal mechanism through which trust may be achieved, although wider evidence suggests that desired performance improvements may only accrue where participation is'meaningful' (Delbridge and Whitfield, 2001). Conversely, EI can be used to intensify the work process and achieve tighter control, although whether this is done through managerial 'commission' or 'omission' remains open to debate. This study sought to explore these questions. The critical realist paradigm was deemed to be the most appropriate methodological approach, and a'firm-insector' approach was applied. This facilitated investigation of meso-level, as well as macro-level, effects on enterpriselevel processes and outcomes. Four manufacturing plants, drawn from the pharmaceuticals and automotive components sectors, constituted the units of analysis. It was postulated that the pharmaceuticals sector might constitute a more conducive environment in which to cultivate trust. Conversely, it was averred that the encroachment of the 'customer' into the management of the employment relationship within the components supply business might encourage a control orientation. In keeping with a general predilection of British management, it was found that 'genuine' trust existed in none of the organisations at the time of the fieldwork (Thompson, 2003; Claydon, 1998). Management sought to (or had done so) substitute 'meaningless' EI for collective organisation. However, at two of the plants, employees reported previous instances where trust had existed. Significantly, this was not confined to the pharmaceutical sector. This facilitated identification of the antecedent conditions necessary for trust to develop, namely a value orientation on the part of senior management, strong organisational performance, effective trade unionism and participative, 'informal' management styles.

Master of Science
Department of Psychology
Kimberly Kirkpatrick
Several studies have examined timing and impulsive choice behavior in spontaneously hypertensive rats (SHR) as a possible pre-clinical model for Attention Deficit Hyperactivity Disorder (ADHD). However, the strain has not been specifically selected for the traits of ADHD and as a result their appropriateness as a model has been questioned. This study investigated whether SHR would exhibit timing deficits, poor reward processing and impulsive behavior in comparison to the Wistar Kyoto (WKY) control strain in a discrete-trial choice task. In addition, as a first approach to find another potential animal model of ADHD, we evaluated a strain that has shown high levels of impulsivity, the Lewis (LEW) rats and compared them with the Wistar (WIS) rats. In the first phase of the experiment, rats could chose a lever associated with a Smaller-sooner (SS) reward of 1 pellet delivered after 10 s and a Larger-later (LL) reward of 2 pellets delivered after 30 s. Subsequently, the rats were exposed to different phases, where the reward on the LL choice was increased to 3 and 4 pellets and where the delay to the SS choice was increased to 15 and 20 s. The SHR and WKY strains did not differ in their timing or choice behavior. In comparison to WIS, LEW showed timing deficits in both manipulations and deficits in choice behavior in the delay manipulation, indicating deficits in time processing. Individual differences among the rat within a strain accounted a significant proportion of the total variance and contributed more variance than the strain of the rat. These results indicate that the SHR and LEW strains are not sufficiently homogeneous with respect to impulsive choice behavior to be considered as viable models for impulse control disorders such as ADHD.

C. halicacabum (Sapindaceae) is an invasive plant that is considered a nuisance species in Texas riparian environments. Little is known of the tolerance of C. halicacabum to flooding and drought; however, this information may provide insight into the characteristics that contribute to C. halicacabum purported invasiveness. C. halicacabum seedlings (n = 92) were exposed to one of four levels of water availability (flooded, saturated, intermediate and dry) over six weeks under greenhouse conditions. Plant performance was affected by water availability; however, there was no effect on survivorship. Flooded and saturated plants exhibited morphological adaptations; producing adventitious roots, hypertrophy, and aerenchyma tissue. Morphological measures, anatomical responses, and patterns of biomass allocation all indicate that C. halicacabum is able to survive periodic inundation, perform in saturation, and establish and thrive on the drier end of a moisture gradient.

This study examined four levels of sexual involvement among adolescents. Levels of sexual involvement were (1) adolescents who had experienced sexual intercourse; (2) adolescents who had been involved in petting but had never had intercourse; (3) adolescents who had made out but had never petted or had sexual intercourse; and (4) adolescents who had never made out, petted, or had sexual intercourse. The sample consisted of 308 eleventh graders from a semi-rural area of the state of Utah. Dating patterns, particularly early age at first date, were found to be significantly associated with most levels of sexual involvement. Early age at first date was associated with a high level of sexual involvement, with 90% of the adolescents who dated at age 13 or before having experienced sexual intercourse by their junior year in high school. Having a steady boyfriend or girlfriend was also associated with a higher level of sexual involvement, with 58% of those who reported having a steady dating partner reporting sexual intercourse involvement. Close relationships with family, father, and mother were more predictive of less female involvement in sexual activity than male. Relationship with mother was not significant for adolescent male sexual involvement. Having peers who approved of adolescent sexual involvement was more associated with male than female sexual activity. Higher frequency of church attendance was a strong predictor of less sexual involvement for both genders. More factors proved to be predictive of adolescent female than male sexual activity on all levels of sexual involvement. A history of sexual abuse and having high educational goals were significantly associated with female sexual involvement only.

University of Central Florida College of Arts and Sciences Thesis
The study examined the nubmer of significant factors in the Hackman and Oldham (1980) job characteristics model. The original factors were: Skill Variety, Task Significance, Task Identity, Autonomy, and Feedback. Scores on these dimensions for 84 employees of the University of Central Florida (21 supervisory and 63 non-supervisory subjects) were used as the basis for this study through a mail administration of the Hackman and Oldham Job Diagnostic Survey (JDS) and their Job Rating Form (JRF). It was hypothesized that: (a) only four significant job dimensions would emerge from factor analysis of the data; (b) that the motiviating potential ratings from job incumbents would be significantly different from those provided by supervisors; and (c) that these motiviating potential scores would be significantly lower than the norm for the job families into which those positions fell. the data failed to lend support to any of the preceeding hypotheses. First, only one significant factor (Skill Variety) was extracted from the non-supervisory data while two factors (Skill Variety and Task Identity) were extracted from the supervisory data. Second, incumbents' ratings were not significantly different from those of their supervisors and third, the motivating potential scores of incumbents were found to be higher than the norm for most of hte job families sampled in the study.
M.S.;
Arts and Sciences;
Industrial/Organizational Psychology
89 p.
viii, 89 leaves, bound : ill. ; 28 cm.

Particular English language learners have a need to demonstrate high levels of accuracy in their written and spoken language production. Dynamic corrective feedback (dynamic CF) has been shown to facilitate L2 learner written accuracy attainment through providing manageable, meaningful, timely and constant feedback on authentic and frequent written language production. The research of this thesis examined the benefits of altering the dynamic CF model to be responsive to students' spoken production rather than solely their written production and measured the impact this adaptation would have on the established benefits of the instructional strategy on students' gains in written accuracy. The study also looked at the impact of both forms of dynamic CF on students' attainment of written complexity, fluency, and lexical development. The study included two groups of students whose language proficiency ranged from intermediate-low to advanced-mid who were studying English for academic purposes in an intensive English language program. These students participated in a one-semester Linguistic Accuracy course. Half of the students received the traditional form of dynamic CF in which they received feedback on only their written production, and the other half received a modified version of dynamic CF that provided students with feedback on only their spoken production. Before and after the treatment, samples of students' written production were collected through a thirty-minute essay test. These writing samples were analyzed for accuracy, fluency, complexity, and lexical development. Changes in each of these variables for both groups were contrasted using a mixed-model repeated measure Analysis of Variance (ANOVA). These tests revealed that there was not a significant difference in terms of the changes in accuracy or lexical development between the two groups; however, participants receiving the modified variation of dynamic CF did perform significantly better on the measurement of written complexity. Also, lower proficiency students receiving the modified version of dynamic CF did significantly better on the measurement of written fluency than students of a similar proficiency receiving the traditional form.

Humans are continuously exposed to complex mixtures of anthropogenic chemicals. This thesis focus on human exposure to persistent organic pollutants (POPs). POPs ability to bioaccumulate and biomagnify together with the extensive historical use of POPs in e.g. agriculture and industry have resulted in detection of these compounds in humans and animals from all over the world. Adverse health effects caused by POPs are of particular concern for newborns and young individuals. The objective of this thesis is to assess human exposure to a selected set of POPs and their metabolites. More specifically, one aim of my thesis is to determine the exposure to polychlorinated biphenyls (PCBs) and in particular their methylsulfonyl and hydroxylated metabolites in humans from a “hot-spot” area of PCB contamination in eastern Slovakia. The maternal transfer of these chemicals is studied. Further, another specific aim is to determine occurrence, levels and, when possible, temporal trends of POPs in children and adults from three developing countries, Nicaragua, Guinea-Bissau and Bangladesh. High concentrations of PCBs and their metabolites are shown in men and women from Michalovce in eastern Slovakia. Placental transfer of methylsulfonyl-metabolites of PCBs and 4,4’-DDE was observed for the first time. Decreasing temporal trends of the majority of POPs are shown in serum from a cohort of policemen from Guinea-Bissau. In contrast, the levels of polybrominated diphenyl ethers (PBDEs) show an increasing time trend. Within five years, decreasing levels of POPs were also shown in children working and living at a waste disposal site in Nicaragua. Children working and living at waste disposal sites in Bangladesh have considerably lower levels of POPs compared to the children from Nicaragua except for 4,4’-DDT and 4,4’-DDE that are present at very high concentrations, indicating ongoing use of technical DDT. There are many studies on levels and trends of environmental pollutants from the developed industrial countries in the world, whereas data from developing countries is still scarce. This thesis contributes to partly fill this data gap since it includes assessments of POPs in children and adults from four countries on four continents.
At the time of doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript. Paper 6: Manuscript.

While much research exists on self-efficacy in music programs, few research studies have qualitatively examined the impact of vocal performance settings on music education majors' self-efficacies and career goals. This collective case study examines the self-efficacy perceptions of four undergraduate vocal music education students in five vocal performance and rehearsal settings: (a) voice lessons, (b) studio classes, (c) choral rehearsals, (d) choral performances, and (e) juries. During a spring semester at a major university in the southwestern United States, I examined how participants' perceptions of their family backgrounds, career goals, lifestyles, peers, and student-teacher relationships influenced their vocal self-efficacy perceptions and music career goals. Data collection included observations, individual interviews with participants, and one focus group interview. Coding methods were used to analyze the interview transcripts and observation field notes. Triangulation, peer review, and member checks of transcriptions were used to ensure accuracy. Findings are documented case-by-case and as cross-case themes. I found that mastery experiences and family support during adolescence influenced participants' initial decisions to major in music but had little influence on vocal self-efficacy during the study. Secondly, self-efficacy changes noted throughout the study influenced participants' career goals. Other emergent themes included the role of memory, teacher feedback, concept comprehension and socialization. I conclude with cross-case themes and offer ideas for future self-efficacy research.

With public opinion shifting to a believe in climate change in the early 2000s the interest in energy efficiency has been increasing. EU Directives set the goal of deploying smart meters if cost efficient for providing more detailed energy consumption. The main goal is to better inform consumers and to give individual households the power to change possibly energy wasting behaviours. This paper evaluates through a literature review the effectiveness of intelligent electricity metering systems with a focus on the DACH region, the provision of different types of feedback and its persistence. It can be concluded that energy feedback enabled by smart meters can lead to savings in the range of 0% to 4.5% in this region. If feedback is provided continuously savings persist. However, several aspects have to be considered to ensure effectiveness of smart meter deployment.

This study was conducted to investigate the effects of four drip irrigation treatments on five fruiting characteristics of cotton (Gossypium hirsutum L.) using periodic observations to gauge the relative impact of these effects over time. The fruiting characteristics measured were: (1) number of flowers, (2) percent boll set, (3) number of bolls, (4) weight boll-1, and (5) seedcotton production. The irrigation treatments included four levels that in total season applied irrigation equaled 60, 68, 76, and 83 cm of water. Periodic observations included three, 3-week-intervals from the onset of flowering (26 June) to cutout (29 August). Results indicate that irrigation treatments had a significant effect on all characters measured, only in the later stages of development (later in the season) with higher amounts of irrigation applied producing higher levels of each character measured. Significant differences were found among periods of observation for all characters measured.

Although the association between elevated serum cholesterol levels and cardiovascular risk has been known for many years, few studies, with freely living individuals have used a full complirnent of intervention strategies to attempt to alter practices associated with elevated serum cholesterol. Two studies, (Study 1, n=4; Study 2, n=8) with 12 middle age men (mean age = 47.3 years) and with elevated serum cholesterol (x= 238.7 mg/dl) are presented that use multiple measures of serum cholesterol (using the Boehringer Mannheim Reflotron and finger stick technique). The main intervention strategies included a combination of procedures using education, frequent serum cholesterol feedback (two to three times per week), and specific dietary feedback (one to two times per week). A less intensive intervention that is similar to recent studies in the literature was also implemented and assessed for half the subjects in Study The results of the two studies indicated that within approximately 14 weeks, the combination of enhanced procedures reduced serum cholesterol by about 14%, or about double that found in prior studies. The less intensive intervention showed reductions of 9.1% The use of multiple measures also allowed for the study of intraindividual variability. issues pertaining to maintenance of effect, cost-effectiveness, and generalizability are also discussed.

Master of Science

In this study I attempted to create a historically informed performance of Handel's Four Coronation Anthems at the pitch of a1 = 423, without the benefit of baroque instruments. The issue of lowering the performance pitch from a1 = 440 to a1 = 423 had varying effects on the singers and instrumentalists. Replicating the baroque sound required some modifications to modern instruments and some mental and vocal adjustments for the singers. Several singers experienced vocal relief due to the lowered pitch, while some instrumentalists were faced with re-adjusting their technique to compensate for the modifications made to their instruments. The modifications ranged from exchanging the violin and viola strings from steel to gut to lengthening the oboe reeds and the bassoon's bocal enough to effectively lower the pitch almost a half step, or .17 Hertz (Hz.). Through the aid of audio and visual recordings of the performance and the performer's questionnaires, several discoveries were made about creating a historically informed performance. Primarily, when changing the pitch of a composition, it is better to adjust the pitch in half steps rather than quarter-tone increments. It was further revealed when changing the pitch that some singers experienced difficulty maintaining pitch due to their vocal muscle memory, whereas, some instrumentalists possess varying degrees of individual pitch memory and perception. In order to deal effectively with the issue of maintaining pitch, it was revealed that it is important to have more rehearsal time at the adjusted pitch. With respect to the modifications made to the instruments, it is vital to the success of the performance to allow the players enough time with modified instruments to be able to maintain consistent tuning within the instrument. The musician's individual pitch perception and preference have an affect on the performance, and the conductor would be well advised to refer to the discoveries presented in this document. This study was successful in discovering ways to present a historically informed performance at a pitch other than a1 = 440 and several suggestions for creating further historically informed performances were explored.

This thesis presents the design of a broadband and high speed dc-coupled AGC amplifier for multi-level (4-PAM) signaling with a symbol rate of 1-GS/s ( 2-Gb/s ) . It is a high frequency analog design with several design challenges such as high -3 dB bandwidth ( greater than 500 MHz ) and highly linear gain while accommodating a large input swing range ( 120 mVp-p to 1800 mVp-p diff.) and delivering constant

differential output swing of 1700 mVp-p to 50-ohm off-chip loads at high speed. Moreover, the gain control circuit has been designed in analog domain. The amplifier incorporates both active and passive feedback in shunt-shunt topology in order to achieve wide bandwidth. This standalone chip has been implemented in AMS 0.35 micron CMOS process. The post layout eye-diagrams seem to be quite satisfactory.

The achievement gap between African American students and other races was continuously widening. School districts across the country were examining several programs to address the issue. This study attempted to examine the overall benefit of summer school attendance on reading achievement. It evaluated the relationship between summer school attendance and lexile levels of African American students from a low socio-economical area, in grades one through four. Participants for the study were not recruited as secondary data was used for the research. The study site school district's secondary data from the summer school session of 2012 was analyzed. The data included the spring 2012 and fall 2012 AimsWeb RCBM scores, along with the lexile levels. The study site school district collected lexile level data before and after summer school instruction. The summer school program was a four-week program that focused on math and reading. The program was voluntary and any student in the school district was able to attend. Data from the AimsWeb RCBM Assessment provided two measures for analysis: fluency and lexile level. The central research question was "What effect will summer school attendance have on reading lexile levels for African American Students from a low socio-economic area?" This quantitative study explored whether attendance in summer school contributed to an increase in the reading level, decrease in the reading level, or no effect on the reading level. This study used secondary data from a controlled group of students who did not attend summer school and an intervention group of students who attended summer school during 2012. A stratified random sampling of 60 students from the school's population of 343 was used to conduct the research.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
O presente estudo foi conduzido objetivando-se avaliar a influÃncia dos nÃveis de inclusÃo e graus de moagem do resÃduo de caju (Anacardium occidentale, L.) sobre o consumo, coeficientes de digestibilidade, parÃmetros de comportamento ingestivo e o pH do lÃquido ruminal de dietas experimentais isoenergÃticas e isoprotÃicas contendo o resÃduo de caju fornecidas a ovinos em terminaÃÃo. Vinte e quatro ovinos foram distribuÃdos em delineamento inteiramente casualizado em esquema fatorial 4 X 2, quatro nÃveis de inclusÃo (11, 21, 28 e 33%) de subproduto de caju em dois graus de moagem (trÃs e 19 mm de diÃmetro da peneira do triturador de grÃos, representando moagem fina e grosseira, respectivamente), em substituiÃÃo ao feno de capim Aruana (Panicum maximum cv. Aruana), milho e torta de algodÃo, perfazendo oito tratamentos experimentais. O consumo, com exceÃÃo das hemiceluloses, e os coeficientes de digestibilidade dos parÃmetros avaliados nÃo foram afetados pelos graus de moagem aplicados ao subproduto de caju. A inclusÃo do subproduto de caju, em dietas para pequenos ruminantes, em atà 33% do total dietÃtico nÃo afeta o consumo. Quando incluso em nÃveis superiores a 21 %, o subproduto de caju pode provocar reduÃÃo nos coeficientes de digestibilidade do EE e FDN dietÃticos. Jà a inclusÃo deste subproduto em nÃveis superiores a 28% à dieta, pode reduzir a digestibilidade da MS, MO, e energia bruta. O tempo gasto com alimentaÃÃo foi reduzido com a inclusÃo do resÃduo em altas proporÃÃes da dieta, entretanto, elevados nÃveis de inclusÃo do resÃduo de caju nÃo promoveram reduÃÃo no tempo gasto com ruminaÃÃo. O pH do lÃquido ruminal foi maior para as dietas com os maiores nÃveis de inclusÃo do resÃduo. Os resultados indicam que o resÃduo de caju pode ser utilizado em dietas para ovinos em terminaÃÃo, nas mesmas condiÃÃes aplicadas neste trabalho, em nÃveis de atà 21%, em ambos os graus de moagem.

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Ting, Lena; Committee Member: Chang, Young-Hui; Committee Member: Nichols, T. Richard; Committee Member: Schumacher, Eric; Committee Member: Thoroughman, Kurt. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This study was conducted in the old arable land located in Lushington communal area in the Eastern Cape province of South Africa. The objectives of the study were to assess the effect of legume introduction on biomass yield, forage and soil mineral levels of the arable lands planted to four leguminous pastures in four seasons. Planting was done in March and October 2008 in Lushington. All legumes were subjected to grow under rain fed conditions. Trifolium vesiculosum (arrowleaf clover), Lespedeza cuneata (sericea lespedeza), Trifolium repens (white clover) and Lotus corniculatus (birdsfoot trefoil) are the four forage legume species that were sampled for the purposes of this study. The four legume species persisted out of the fourteen species that were initially tested for adaptability and persistence in the environmental conditions of Lushington communal area. The legumes, grasses and soils from these legume plots were sampled to determine the effect of legume introduction on the forage yield, mineral contents of the companion grasses and soils over four seasons. Plant and soil samples were collected once in spring (November) 2013, summer (February), autumn (March) and winter (May) 2014 for biomass production, macro and micronutrients determination. Results indicated that legume inclusion and season affected (P < 0.05) the total dry matter (TDM) yield production. Plots with Lespedeza cuneata had the highest TDM (1843 kg/ha) and control plots had the least dry matter production (1091 kg/ha). Summer season provided the highest (P < 0.05) TDM compared to the other seasons. Both legume and grass quality was also affected (P < 0.05) by legume inclusion in different seasons. Accordingly, grasses harvested from Trifolium repens plot showed higher CP level (10.90 percent) than those harvested from other plots whereas the lowest grass CP content (6.90 percent) was measured in the control treatment. L. cuneate had the highest (P < 0.05) CP level (11.00 percent) and T. repens had the least CP (6.63 percent) level. Grasses harvested in autumn had the highest (P < 0.05) CP level (12.50 percent) and those harvested in winter had the least CP level (4.60 percent). Similarly, all legume pastures harvested in spring had superior (P < 0.05) CP (10.80 percent) levels and those harvested in winter had the least CP (3.50 percent) level. Legume inclusion had an effect (P < 0.05) on both grass and legume macro nutrient contents. Trifolium repens plot had the highest grass K (1.07 percent), Ca (1.50 percent) and Mg (1.83 percent), whereas there were lower K (0.12 percent), Ca (1.25 percent) and Mg (1.08 percent) contents in grasses harvested from the control and T. vesiculosum plots, respectively. In legumes, macro nutrient concentrations: K (0.68 percent), Ca (1.75 percent) were superior in the T. vesiculosum plot in comparison to other plots. Season also affected (P < 0.05) both grass and legume macro nutrient content. There was higher K (0.90 percent), Ca (1.30 percent) and Mg (0.94 percent) content in grasses harvested in autumn whereas there were lower levels in winter harvests. In legumes, superior K (0.74 percent) and Mg (1.87 percent) content were attained during spring while the least were measured in winter (0.07 percent) and autumn (0.75 percent), respectively. Likewise, both legume inclusion and season had an significant effect (P < 0.05) on the forages micronutrient levels. During spring, there was superior soil P content (36.28 mg/kg) while during autumn; there was less P (22.58 mg/kg) content. The highest SOC level (1.49 percent) was measured in the T. repens plot whereas the lowest SOC (1.15 percent) was attained in the control plot. The results of this study showed that grass legume mixtures produced forages with high nutrient content and herbage yield. Legume planting in the old arable lands has a potential to improve soil quality parameters such as soil P and SOC content.

African American women ages 25-44 have been identified as one of the most at risk groups for HIV/AIDS infection. This study examines the factors which contribute to HIV risk behavior, predict HIV risk behavior, and impact HIV risk behavior reduction. Objectives of this study are to identify the types and prevalence of HIV risk behavior in a sample of African American women ages 25-44, and to determine the extent to which seven identified psychosocial variables predict HIV risk behavior in this sample of women. The variables are HIV risk knowledge, perceived HIV risk, risk reduction behavior intentions, perceptions of safer sex peer norms, condom barrier beliefs, conversations with male partners about condom and AIDS concerns, and substance use patterns. Anonymous questionnaires were administered to 148 African American women ages 25-44 who were enrolled in graduate classes at Clark Atlanta University. The purpose was to determine their levels of HIV risk behavior and predictors of HIV risk practices. Results indicate over one half of the women were at high risk for HIV because of inconsistent or no condom use during sexual intercourse and sexual relationships with multiple and high risk male partners. HIV risk was significantly higher among women who held weak behavioral intentions to reduce risk behavior through condom use, perceived more relationship barriers to condom use, believed peer norms did not support condom use, and accurately perceived themselves at high personal risk for HIV infection. HIV prevention and interventions efforts are needed that effectively incorporate attitudes, communication modes, and behavior change methods congruent with the values of African American men and women for whom the efforts are designed. Prevention and intervention should focus on increasing intentions to reduce risk behavior and overcoming barriers to condom use.

Abstract  The present work is a quantitative and qualitative analysis of pragmatic strategies for delivering critique, and types of politeness, used by undergraduate L2 students of English at different stages of peer-review discussion. The material examined consists of four corpora of authentic conversations between students, the main purpose of which was to give feedback on each other’s contributions during an English A-level course, at Mid-Sweden University. The conversations explored were carried out electronically, and represent four different online environments, or modes of computer-mediated communication (CMC). The material from the two asynchronous modes of CMC is comprised of L2 students’ written discussion board messages and spoken posts recorded using online software. The two synchronous environments under investigation are text-based and voice-based chat. Taking Brown and Levinson’s (1987) framework of politeness as a point of departure, the present study uses a combination of corpus and conversation analytical methods. The basic unit of analysis has been defined as the shortest message of peer-review critique that constitutes a thematic unit: these have been examined in terms of their content and politeness features associated with them, and analyzed in terms of the pragmatic strategy and type of politeness adopted. The types of pragmatic strategies or message organization patterns at different stages, i.e. initial versus subsequent feedback, of the peer-review discussion have also been analyzed. The results of the study show that the pragmatic strategies aimed at praise and agreement prevail in the corpus data produced by predominantly native speakers of Swedish. Even though the pragmatic strategies used for disagreement and negative evaluation are rich in propositional content, their occurrences and distribution vary across the four modes of CMC examined. These results seem to have wider implications in the context of online L2 learning activities, providing insights about the language of peer-review critique in a Swedish academic setting.   Keywords: computer-mediated communication (CMC), Conversation Analysis (CA), conversation management, discussion boards, feedback category, mode of CMC, peer-review discussion, politeness theory, pragmatic strategy, speech act of critique, text-based chat, type of politeness, voice-based chat, VoiceThread

The purpose of this study was to determine the impact of the levels of implementation of four Response to Intervention (RTI) components on the overall special education referral rates of elementary school students at 35 schools. The four RTI components are (a) using intervention teams to problem-solve for struggling students, (b) selecting the appropriate intervention, (c) monitoring student progress, and (d) graphing data for visual analysis. The four levels of implementation are (a) lacks skills or basic knowledge of this component, (b) beginning to learn this component (beginning level), (c) developing skill with this component (intermediate level), and (d) fully competent in this component (advanced level).

Data were analyzed on 483 responders from 35 elementary schools. The quantitative research designs were the descriptive-survey and causal comparative designs. Findings for research question one showed the highest percentages of responders from the schools perceived the four components were at the advanced level or intermediate level of implementation. Results for research question two showed the male subgroup had the highest mean referral rate, while the African American subgroup had the second highest mean referral rate.

For research question three, findings showed there was a significant difference in the referral rate for special education services based on the implementation levels of RTI (F(2, 32) = 7.25, p = 0.003. Results for research question four showed the level of implementation had an impact on the rate of referral for special education services based on demographic factors of gender and ethnicity.

Ph. D.

La représentation de la consommation d’électricité et des comportements associés est abordée sous l’angle des anticipations que l’individu met en œuvre. Selon la théorie des niveaux de construit (Trope & Liberman, 2003) nous avons demandé à des individus d’apprécier leur consommation d’électricité en termes de gestes (bas niveau de construit) et de consommation (haut-niveau de construit) à différentes échelles temporelles (d’aujourd’hui à 15 ans). Dans un premier programme de recherche, les estimations étaient exprimées en termes comparatifs (se comparer à quelqu’un de votre âge). Une distance temporelle longue entraîne des estimations plus désirables dans le sens où les individus (population étudiante et générale) déclarent davantage d’actions chez eux que leurs pairs. Les participants déclarent effectuer plus de gestes et consommer moins d’électricité à long terme plutôt qu'à court terme. Cet effet est annulé par des habitudes pro-environnementales fortes et disparait au-delà de 50 ans. Des feedbacks normatifs permettent de corriger ces estimations. Un second programme de recherche portait sur l’influence de feedbacks normatifs sur la mise en veille de son ordinateur dans un contexte professionnel. Ce type de feedback permet d’obtenir une augmentation importante de mise en veille (jusqu’à un mois après) chez les individus effectuant peu par le passé ce comportement. La promotion de la réduction de la consommation d’électricité peut être renforcée par les niveaux de construit et les feedbacks normatifs
The representation of electric energy consumption and the-related behaviours is addressed from the perspective of the individual's forecasting. According to the construal level theory (Trope & Liberman, 2003) we asked individuals to assess their electric energy consumption in terms of actions (low level of construal) and consumption (high level of construal) at different time perspectives (from today to 15 years from now). In a first research program, the assessments were expressed comparatively (same as people of my age). A long temporal distance leads to more desirable assessments in that the individuals (students and general population) reported more actions relatively to their peers. Participants stated that they would perform more actions and consume less electric energy consumption in long term rather than short term. This effect is cancelled through strong pro-environmental habits and disappears beyond 50 years old. Normative feedbacks allow for correcting these assessments. A second research program dealt with the influence of normative feedbacks on the use of the computer sleep mode within a professional context. This type of feedback provides significant increase in setting up sleep mode (up to one month after) for individuals that previously didn't do it much. The promotion of energy conservation can be enhanced by construal levels and normative feedbacks

Cette thèse se développe sur deux fronts: nous nous concentrons sur les méthodes numériques des problèmes de contrôle optimal, en particulier sur le Principe de la Programmation Dynamique et sur le Model Predictive Control (MPC) et nous présentons des applications de techniques de contrôle en biologie. Dans la première partie, nous considérons l'approximation d'un problème de contrôle optimal avec horizon infini, qui combine une première étape, basée sur MPC permettant d'obtenir rapidement une bonne approximation de la trajectoire optimal, et une seconde étape, dans la quelle l¿équation de Bellman est résolue dans un voisinage de la trajectoire de référence. De cette façon, on peux réduire une grande partie de la taille du domaine dans lequel on résout l¿équation de Bellman et diminuer la complexité du calcul. Le deuxième sujet est le contrôle des méthodes Level Set: on considère un problème de contrôle optimal, dans lequel la dynamique est donnée par la propagation d'un graphe à une dimension, contrôlé par la vitesse normale. Un état finale est fixé, l'objectif étant de le rejoindre en minimisant une fonction coût appropriée. On utilise la programmation dynamique grâce à une réduction d'ordre de l'équation utilisant la Proper Orthogonal Decomposition. La deuxième partie est dédiée à l'application des méthodes de contrôle en biologie. On présente un modèle décrit par une équation aux dérivées partielles qui modélise l'évolution d'une population de cellules tumorales. On analyse les caractéristiques du modèle et on formule et résout numériquement un problème de contrôle optimal concernant ce modèle, où le contrôle représente la quantité du médicament administrée
This thesis is divided in two parts: in the first part we focus on numerical methods for optimal control problems, in particular on the Dynamic Programming Principle and on Model Predictive Control (MPC), in the second part we present some applications of the control techniques in biology. In the first part of the thesis, we consider the approximation of an optimal control problem with an infinite horizon, which combines a first step based on MPC, to obtain a fast but rough approximation of the optimal trajectory and a second step where we solve the Bellman equation in a neighborhood of the reference trajectory. In this way, we can reduce the size of the domain in which the Bellman equation can be solved and so the computational complexity is reduced as well. The second topic of this thesis is the control of the Level Set methods: we consider an optimal control, in which the dynamics is given by the propagation of a one dimensional graph, which is controlled by the normal velocity. A final state is fixed and the aim is to reach the trajectory chosen as a target minimizing an appropriate cost functional. To apply the Dynamic Programming approach we firstly reduce the size of the system using the Proper Orthogonal Decomposition. The second part of the thesis is devoted to the application of control methods in biology. We present a model described by a partial differential equation that models the evolution of a population of tumor cells. We analyze the mathematical and biological features of the model. Then we formulate an optimal control problem for this model and we solve it numerically

In Particle Accelerators, the Low-Level RF (LLRF) is the control system of the RF, and in the end, of the purpose of the machine, that is the energy transfer and acceleration of particles. It implements algorithms synchronizing the RF conveying the energy to the beam and tailoring its longitudinal parameters. For this, the LLRF uses beam-related signals whose spectral content changes during the acceleration. The increase in energy results in an increase of the beam velocity, and for circular accelerators (Synchrotrons) a decrease in revolution period. This is especially relevant for Hadron machines whose injection energy is low resulting in a significant increase of their velocity before reaching relativistic speeds. Hence, the LLRF needs to continuously tune its processing to the beam; we call this technique Beam Synchronous Processing. One important task of the LLRF is the compensation of the beam-induced voltage in the accelerating cavities (Beam Loading). In the CERN SPS the regulation bandwidth must cover 5 MHz on each side of the 200 MHz RF. With a beam revolution period around 23 µs more than a hundred revolution frequency harmonics, present in the beam signal, fall in the RF sidebands. The variation in beam velocity changes the position and spacing of the harmonics in the spectrum. The large number of harmonics and their varying positions make the algorithm reconfiguration an undesirable option. To cope with this, the early digital implementations used a system clock derived from the sweeping RF. This locks the sampling and the processing to the beam, by design. This historical solution, that is still in use in several machines, is now a limiting factor for the use of modern technologies. The Thesis presents a novel Beam Synchronous Processing Architecture, using a fixed frequency clocking, and capable of treating periodic signals with known and varying fundamental frequency. The Architecture is an alternative to the burden of reconfiguration in processing algorithms; it tunes the spectrum to the processing by resampling the input data. Two Resamplers are combined in the so-called resampling sandwich. The application algorithm requiring synchronism with the input signal is placed in the middle. The key element is a novel All-Digital Farrow-based Resampler, that accepts arbitrary resampling ratios that can be modified in real-time. The hardware uses a single fixed frequency system clock, making its implementation feasible in State-Of-the-Art FPGAs, ASICs and systems such as the new uTCA platform currently being deployed in the CERN SPS LLRF system. The input and output ports of the Resampler, and all the processing within the Architecture, are synchronous to this fixed frequency clock and accept data streams whose sampling rate can be variable and modified in real time. The Architecture has been commissioned in a LLRF uTCA crate hosting the One Turn FeedBack algorithm to control a real SPS cavity. The algorithm compensates the Beam Loading. The Architecture has demonstrated its capability to track in real-time an energy ramp with an RF frequency following a linear sawtooth pattern ramped at 2.4 MHz per second. The complete uTCA implementation has successfully passed all the functional validation and qualitative tests. The Architecture suits seamless the two technological paradigm changes adopted for the new CERN SPS LLRF system; first, the instantaneous value of the RF frequency is transmitted as a numerical word (used to set the resampling ratio), via a deterministic network, the White Rabbit. And second, the reference signal is now the fixed frequency clock recovered from this network. Both paradigms benefit from the all-digital Resampler and the Beam Synchronous Architecture that fulfil the techniques and technological needs for its implementation enabling novel LLRF algorithms and solutions.
En un Acelerador de Partículas, el Low Level RF (LLRF) es el sistema de control de la RF, e implícitamente, de la transferencia de energía y aceleración de partículas, objetivo último de la máquina. El LLRF implementa algoritmos que sincronizan la transferencia de energía de RF hacia el haz, y controla sus parámetros longitudinales. Usa señales del haz, cuyo contenido espectral se modifica con la aceleración. El incremento en energía implica un incremento en velocidad del haz que, para aceleradores circulares (Sincrotrones), resulta en un decremento del periodo de revolución. Esto es relevante en aceleradores de Hadrones, en los cuales la baja energía de inyección favorece grandes incrementos de velocidad antes de alcanzar valores relativistas. El LLRF necesita por tanto sintonizar continuamente el procesado y el haz (Beam Synchronous Processing). Una misión del LLRF es la compensación de la tensión inducida por el haz en cavidades aceleradoras (Beam Loading). En el sincrotrón SPS del CERN, el ancho de banda de regulación cubre 5 MHz a cada lado de la RF (200 MHz). Con un periodo de revolución de aproximadamente 23 µs, más de cien harmónicos de la frecuencia de revolución, presentes en la señal del haz, aparecen en las bandas alrededor de la RF. La variación en velocidad del haz cambia la posición y espaciado de estos harmónicos en el espectro. Su número y posición cambiante hacen una opción poco deseable la reconfiguración en algoritmos de control. La solución histórica es un reloj de sistema derivado de la RF, por tanto variable, que liga por diseño el muestreo y procesado al haz. Aún en uso en varias máquinas, este reloj es ahora un factor limitante para el uso de nuevas tecnologías. Esta Tesis presenta una nueva Arquitectura para Tratamiento Síncrono de Señales derivadas del Haz, mediante un reloj de sistema con frecuencia fija, que posibilita el tratamiento de señales periódicas en las que el harmónico fundamental tiene una frecuencia variable y conocida. La Arquitectura es una alternativa válida al problema de reconfiguración de algoritmos de procesado; sintoniza el espectro al procesado mediante el re-muestreo de los datos. Dos Re-muestreadores (Resamplers) son combinados en el denominada sándwich de re-muestreo. El algoritmo requiriendo sincronismo con el haz, se sitúa en medio de este sándwich. El elemento clave es un novedoso Resampler digital que acepta relaciones de re-muestreo arbitrarias y modificables en tiempo real. El hardware usa un único reloj de sistema de frecuencia fija, facilitando la implementación en FPGAs, ASICs y sistemas de última generación, como los controladores uTCA en los sistemas LLRF del SPS en el CERN. Los puertos de entrada y salida del Resampler, y todo el procesado en la Arquitectura, son síncronos a este reloj, y aceptan señales con una frecuencia de muestreo variable en tiempo real.La Arquitectura ha sido implementada en un controlador uTCA de una cavidad del SPS albergando el algoritmo One Turn FeedBack. El algoritmo compensa el Beam Loading. La Arquitectura demuestra ser viable operando sintonizada a una rampa de aceleración del haz, con una RF cuya frecuencia varia linealmente a 2.4 MHz por segundo siguiendo un patrón en diente de sierra. La implementación de la Arquitectura ha pasado toda la validación funcional y test cualitativos. La Arquitectura se adapta de manera sin igual a dos cambios de paradigma tecnológico adoptados por el LLRF del SPS; primero, la distribución del valor instantáneo de la frecuencia de RF es ahora hecho mediante una palabra digital con una red determinista, White Rabbit. Y segundo, la señal de referencia es ahora un reloj con frecuencia fija extraído de esta red. La adopción de ambos paradigmas se ve beneficiada por el uso de la Arquitectura y Resampler, que satisfacen los requerimientos técnicos y tecnológicos para la implementación de nuevos algoritmos y soluciones LLRF.
Dans le monde des Accélérateurs de Particules, le Low-Level RF (LLRF) est le système de contrôle de la RF et, in-fine, du transfert d'énergie et de l'accélération des particules. Il met en oeuvre des algorithmes synchronisant la RF transférant l'énergie au faisceau et adaptant ses paramètres longitudinaux. Pour cela, le LLRF utilise des signaux liés au faisceau dont le contenu spectral est modifié par l'accélération. L'augmentation d'énergie se traduit par une augmentation de la vitesse du faisceau, et pour les accélérateurs circulaires (Synchrotrons), une diminution de la période de révolution. Cela est particulièrement pertinent pour les machines à Hadrons dont l’énergie d’injection est faible, avec la conséquence d’une augmentation significative de leur vitesse durant l’accélération. Le LLRF doit donc ajuster en permanence son traitement au faisceau ; nous appelons cette exigence Beam Synchronous Processing. Une tâche importante du LLRF est la compensation de la tension induite par le faisceau (Beam Loading). Dans le SPS au CERN, la régulation couvre 5 MHz de chaque côté de la RF (200 MHz). Avec une période de révolution autour de 23 μs, plus d'une centaine d’harmoniques de fréquence de révolution, présentes dans le spectre du faisceau, tombent dans la bande +- 5 MHz. La variation de vitesse du faisceau modifie la position et l'espacement des harmoniques dans le spectre. Le grand nombre de raies spectrales et leur position variable font de la reconfiguration de l'algorithme une option indésirable. Les solutions digitales existantes ont donc préféré changer l’horloge d’échantillonnage : Celle-ci est verrouillée sur la RF, ce qui synchronise par conception l'échantillonnage et le traitement du faisceau. Cette solution historique, toujours en usage dans plusieurs machines, est aujourd'hui un facteur limitant pour les technologies modernes. La Thèse présente une nouvelle Architecture de traitement synchrone de faisceau, utilisant une horloge fixe, et capable de traiter des signaux périodiques de fréquence fondamentale connue et possiblement variable. L'Architecture apporte une alternative au fardeau de la reconfiguration dans les algorithmes ; il ajuste le spectre au traitement en rééchantillonnant les données d'entrée. Deux Rééchantillonneurs ont été combinés dans le sandwich de rééchantillonnage. L'algorithme d'application nécessitant un synchronisme avec le signal d'entrée est placé au milieu. L'élément clé est un nouveau Ré-échantillonneur entièrement numérique basé sur une architecture Farrow, qui accepte des taux de rééchantillonnage arbitraires pouvant également être modifiés en temps réel. L’implémentation utilise une seule horloge système à fréquence fixe, ce qui rend sa mise en œuvre possible dans les FPGA, ASIC et systèmes de pointe comme la nouvelle plate-forme uTCA actuellement déployée dans le SPS du CERN. L’entrée et la sortie du Ré-échantillonneur, et tout le traitement dans l'Architecture, sont synchrones avec cette horloge et acceptent un taux d’échantillonnage variable que peut être modifiée en temps réel. L'Architecture a été déployée dans un châssis uTCA hébergeant l'algorithme One Turn FeedBack pour contrôler une véritable cavité SPS. L'algorithme compense le Beam Loading. L'Architecture a démontré sa capacité à suivre en temps réel une rampe d'énergie avec une fréquence RF suivant une modulation en dent de scie, à 2.4 MHz par seconde. L’implémentation complète sur uTCA a passé avec succès les tests de validation fonctionnelle et qualitative. L'Architecture convient parfaitement aux deux paradigmes technologiques adoptés pour le nouveau système LLRF du SPS ; premièrement, la valeur instantanée de la fréquence RF est transmise sous forme de mot numérique (qui donnera le taux de rééchantillonnage), via un réseau déterministe, le White Rabbit. Et deuxièmement, le signal de référence est maintenant l'horloge à fréquence fixe récupérée de ce réseau. La solution présentée respecte ces deux paradigmes grâce au Réchantillonneur entièrement numérique et à l'horloge fixe.
Ciència i enginyeria de materials

 

The interaction between light and organometallic chromophores has been investigated theoretically in a strive for fast optical filters. The main emphasis is on two-photon absorption and excited state absorption as illustrated in the Jablonski diagram. We stress the need for relativistic calculations and have developed methods to address this issue. Furthermore, we present how quantum chemical calculations can be combined with Maxwell's equations in order to simulate propagation of laser pulses through a materials doped with chromophores with high two-photon absorption cross sections. Finally, we also discuss how fast agile filters using spin-transition materials can be modeled in order to accomplish theoretical material design.

Report code: LIU-TEK-LIC-2006:55. On the day of the defence date the status on article III was Manuscript, article IV was Accepted and article V was Submitted.