853 resultados para Directly modulated feedback


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Drought is the main constraint on wheat yield in Mediterranean conditions. The photosynthesis, chlorophyll fluorescence and plant growth parameters of durum wheat (Triticum turgidum, L. var. durum) were compared at three [CO2] (i.e., depleted 260 ppm, current 400ppm and elevated 700 ppm) in plants subjected to twowater regimes (i.e.,well-wateredWW, and mildwater stress by drought orwater deficit WS), during pre-anthesis, post-anthesis and the end of grain filling. We showed that [CO2] effects on plants are modulated by water availability. Plants at depleted [CO2] showed photosynthetic acclimation (i.e., up-regulation) and reduced plant biomass and Harvest Index, but depleted [CO2] combined with WS has a more negative impact on plants with decreases in C assimilation and biomass. Plants at elevated [CO2] had decreased plant growth and photosynthesis in response to a down-regulation mechanism resulting from a decrease in Rubisco and N content, but plants exposed to a combination of elevated [CO2] and WS were the most negatively affected (e.g., on plant biomass).

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Feedback-related negativity (FRN) is an ERP component that distinguishes positive from negative feedback. FRN has been hypothesized to be the product of an error signal that may be used to adjust future behavior. In addition, associative learning models assume that the trial-to-trial learning of cueoutcome mappings involves the minimization of an error term. This study evaluated whether FRN is a possible electrophysiological correlate of this error term in a predictive learning task where human subjects were asked to learn different cueoutcome relationships. Specifically, we evaluated the sensitivity of the FRN to the course of learning when different stimuli interact or compete to become a predictor of certain outcomes. Importantly, some of these cues were blocked by more informative or predictive cues (i.e., the blocking effect). Interestingly, the present results show that both learning and blocking affect the amplitude of the FRN component. Furthermore, independent analyses of positive and negative feedback event-related signals showed that the learning effect was restricted to the ERP component elicited by positive feedback. The blocking test showed differences in the FRN magnitude between a predictive and a blocked cue. Overall, the present results show that ERPs that are related to feedback processing correspond to the main predictions of associative learning models. ■

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The skill of programming is a key asset for every computer science student. Many studies have shown that this is a hard skill to learn and the outcomes of programming courses have often been substandard. Thus, a range of methods and tools have been developed to assist students’ learning processes. One of the biggest fields in computer science education is the use of visualizations as a learning aid and many visualization based tools have been developed to aid the learning process during last few decades. Studies conducted in this thesis focus on two different visualizationbased tools TRAKLA2 and ViLLE. This thesis includes results from multiple empirical studies about what kind of effects the introduction and usage of these tools have on students’ opinions and performance, and what kind of implications there are from a teacher’s point of view. The results from studies in this thesis show that students preferred to do web-based exercises, and felt that those exercises contributed to their learning. The usage of the tool motivated students to work harder during their course, which was shown in overall course performance and drop-out statistics. We have also shown that visualization-based tools can be used to enhance the learning process, and one of the key factors is the higher and active level of engagement (see. Engagement Taxonomy by Naps et al., 2002). The automatic grading accompanied with immediate feedback helps students to overcome obstacles during the learning process, and to grasp the key element in the learning task. These kinds of tools can help us to cope with the fact that many programming courses are overcrowded with limited teaching resources. These tools allows us to tackle this problem by utilizing automatic assessment in exercises that are most suitable to be done in the web (like tracing and simulation) since its supports students’ independent learning regardless of time and place. In summary, we can use our course’s resources more efficiently to increase the quality of the learning experience of the students and the teaching experience of the teacher, and even increase performance of the students. There are also methodological results from this thesis which contribute to developing insight into the conduct of empirical evaluations of new tools or techniques. When we evaluate a new tool, especially one accompanied with visualization, we need to give a proper introduction to it and to the graphical notation used by tool. The standard procedure should also include capturing the screen with audio to confirm that the participants of the experiment are doing what they are supposed to do. By taken such measures in the study of the learning impact of visualization support for learning, we can avoid drawing false conclusion from our experiments. As computer science educators, we face two important challenges. Firstly, we need to start to deliver the message in our own institution and all over the world about the new – scientifically proven – innovations in teaching like TRAKLA2 and ViLLE. Secondly, we have the relevant experience of conducting teaching related experiment, and thus we can support our colleagues to learn essential know-how of the research based improvement of their teaching. This change can transform academic teaching into publications and by utilizing this approach we can significantly increase the adoption of the new tools and techniques, and overall increase the knowledge of best-practices. In future, we need to combine our forces and tackle these universal and common problems together by creating multi-national and multiinstitutional research projects. We need to create a community and a platform in which we can share these best practices and at the same time conduct multi-national research projects easily.

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I likhet med vanliga plaster är de π-konjugerade polymererna flexibla, lösliga och processbara vid låga temperaturer (< 150 ºC). Därutöver har de egenskapen att leda ström. Konduktivitetsintervallet är brett och omfattar nästintill metallisk ledningsförmåga å ena sidan, via halvledarkonduktiva till isolerande å andra sidan. Polymererna utgörs av regelbundna kedjor av kolatomer och associeras sålunda till organiska material. Sedan de första vetenskapliga rapporterna publicerades vid slutet av 1970-talet har π-konjugerade polymerer använts och utvecklats i exempelvis solceller, dioder, lysdioder och transistorer. Nobelpriset i kemi tilldelades år 2000 åt Hideki Shirakawa, Alan J. Heeger och Alan G. MacDiarmid för upptäckten och utvecklandet av ledande polymerer. I min avhandling har jag arbetat med att utveckla och förstå lågspännings jonmodulerade organiska transistorer. Två typer av jonmodulerade organiska transistorer studeras: (1) den jonmodulerade organiska fälteffekt transistorn (jonmodulerade OFETen), som utgör den centrala transistorn i avhandlingen, samt (2) den elektrokemiska transistorn. Den första typen fungerar som en konventionell OFET. Strömmen i halvledaren moduleras av det elektriska fältet över isolatorn. Med användandet av en elektrolyt ”isolator” orsakar polariseringen av jonerna däremot ett högt elektriskt fält vid elektrolyt/halvledargränssnittet och man åstadkommer modulering av strömmen redan vid några volts drivspänningar. I den andra typen utnyttjas elektrokemi för att medelst reduktion/oxidation modulera strömmen i den π-konjugerade polymeren. Ett viktigt ändamål i avhandlingen har också varit att kunna tillverka transistorerna med masstillverkningsmetoder. I avhandlingen presenteras de jonmodulerade organiska transistorernas möjlighet att framställas med masstillverkningsmetoder. Nya koncept introduceras och svagheter identifieras. Skillnaderna mellan OFETen, jonmodulerade OFETen och den elektrokemiska transistorn klargörs. Arbetet skall däremot inte anses fullbordat utan forskningen fortgår för att kringgå svagheterna, öka på transistorernas stabilitet och framförallt tillämpa dem i innovativa applikationer.

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Fornecer feedback aos alunos é um importante aspecto da aprendizagem e um papel essencial dos docentes. No contexto da educação médica clínica, feedback se refere às informações que descrevem o desempenho dos alunos em determinada situação ou atividade. A habilidade de dar e receber feedback melhora os resultados da aprendizagem, uma vez que fornece a base para a aprendizagem autodirecionada e para a reflexão crítica, auxilia os alunos a corrigirem seus erros, reforça comportamentos desejáveis e mostra como o aluno pode melhorar. Apesar da evidente falta de feedback durante o curso médico, os alunos desejam e valorizam essa ferramenta construtiva, considerando-a um aspecto importante do ensino de qualidade. O feedback eficaz deve ser: assertivo, respeitoso, descritivo, oportuno e específico. Docentes e alunos deveriam ser preparados para dar e receber feedback. Coordenadores e diretores deveriam reconhecer o papel do feedback como uma importante estratégia de ensino- aprendizagem na graduação.

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A avaliação é fundamental para o processo ensino-aprendizagem. Diferentes métodos de avaliação e diversos atores envolvidos na avaliação podem fornecer elementos distintos, que, somados, fornecem melhor compreensão sobre a efetividade do processo educacional em suas variadas dimensões. A avaliação de habilidades e atitudes de estudantes tem recebido grande atenção recentemente. O envolvimento de pacientes no processo pode ser contributivo, pois sua perspectiva acrescenta informações ímpares. O presente estudo avaliou a aquisição de competências e habilidades de estudantes de Medicina no internato de Obstetrícia, sob o ponto de vista de gestantes. As pacientes responderam a um questionário segundo escala de Likert, com itens de avaliação divididos em habilidades de comunicação, exame físico e profissionalismo. Os resultados mostraram boa avaliação dos estudantes em geral, o que atribuímos ao sentimento de gratidão das pacientes. Algumas questões com maiores frequências de respostas negativas, porém, apontam aspectos que merecem maior atenção da escola médica pelo impacto que podem trazer à prática profissional. A perspectiva de pacientes na avaliação do estudante de Medicina poderá balizar estratégias de feedback para qualificar a formação médica.

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The use of intensity-modulated radiotherapy (IMRT) has increased extensively in the modern radiotherapy (RT) treatments over the past two decades. Radiation dose distributions can be delivered with higher conformality with IMRT when compared to the conventional 3D-conformal radiotherapy (3D-CRT). Higher conformality and target coverage increases the probability of tumour control and decreases the normal tissue complications. The primary goal of this work is to improve and evaluate the accuracy, efficiency and delivery techniques of RT treatments by using IMRT. This study evaluated the dosimetric limitations and possibilities of IMRT in small (treatments of head-and-neck, prostate and lung cancer) and large volumes (primitive neuroectodermal tumours). The dose coverage of target volumes and the sparing of critical organs were increased with IMRT when compared to 3D-CRT. The developed split field IMRT technique was found to be safe and accurate method in craniospinal irradiations. By using IMRT in simultaneous integrated boosting of biologically defined target volumes of localized prostate cancer high doses were achievable with only small increase in the treatment complexity. Biological plan optimization increased the probability of uncomplicated control on average by 28% when compared to standard IMRT delivery. Unfortunately IMRT carries also some drawbacks. In IMRT the beam modulation is realized by splitting a large radiation field to small apertures. The smaller the beam apertures are the larger the rebuild-up and rebuild-down effects are at the tissue interfaces. The limitations to use IMRT with small apertures in the treatments of small lung tumours were investigated with dosimetric film measurements. The results confirmed that the peripheral doses of the small lung tumours were decreased as the effective field size was decreased. The studied calculation algorithms were not able to model the dose deficiency of the tumours accurately. The use of small sliding window apertures of 2 mm and 4 mm decreased the tumour peripheral dose by 6% when compared to 3D-CRT treatment plan. A direct aperture based optimization (DABO) technique was examined as a solution to decrease the treatment complexity. The DABO IMRT technique was able to achieve treatment plans equivalent with the conventional IMRT fluence based optimization techniques in the concave head-and-neck target volumes. With DABO the effective field sizes were increased and the number of MUs was reduced with a factor of two. The optimality of a treatment plan and the therapeutic ratio can be further enhanced by using dose painting based on regional radiosensitivities imaged with functional imaging methods.

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Robotic grasping has been studied increasingly for a few decades. While progress has been made in this field, robotic hands are still nowhere near the capability of human hands. However, in the past few years, the increase in computational power and the availability of commercial tactile sensors have made it easier to develop techniques that exploit the feedback from the hand itself, the sense of touch. The focus of this thesis lies in the use of this sense. The work described in this thesis focuses on robotic grasping from two different viewpoints: robotic systems and data-driven grasping. The robotic systems viewpoint describes a complete architecture for the act of grasping and, to a lesser extent, more general manipulation. Two central claims that the architecture was designed for are hardware independence and the use of sensors during grasping. These properties enables the use of multiple different robotic platforms within the architecture. Secondly, new data-driven methods are proposed that can be incorporated into the grasping process. The first of these methods is a novel way of learning grasp stability from the tactile and haptic feedback of the hand instead of analytically solving the stability from a set of known contacts between the hand and the object. By learning from the data directly, there is no need to know the properties of the hand, such as kinematics, enabling the method to be utilized with complex hands. The second novel method, probabilistic grasping, combines the fields of tactile exploration and grasp planning. By employing well-known statistical methods and pre-existing knowledge of an object, object properties, such as pose, can be inferred with related uncertainty. This uncertainty is utilized by a grasp planning process which plans for stable grasps under the inferred uncertainty.

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Target company of this study is a large machinery company, which is, inter alia, engaged in energy and pulp engineering, procurement and construction management (EPCM) supply business. The main objective of this study was to develop cost estimation of the target company by providing more accurate, reliable and up-to-date information through enterprise resource planning (ERP) system. Another objective was to find cost-effective methods to collect total cost of ownership information to support more informed supplier selection decision making. This study is primarily action-oriented, but also constructive, and it can be divided in two sections: theoretical literature review and empirical study on the abovementioned part of the target company’s business. Development of information collection is, in addition to literature review, based on nearly 30 qualitative interviews of employees at various organizational units, functions and levels at the target company. At the core of development was to make initial data more accurate, reliable and available, a necessary prerequisite for informed use of the information. Certain development suggestions and paths were presented in order to regain confidence in ERP system as information source by reorganizing work breakdown structure and by complementing mere cost information with quantitative, technical and scope information. Several methods to use the information ever more effectively were also discussed. While implementation of the development suggestions outreached the scope of this study, it was forwarded in test environment and interest groups.

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Over the past decade, organizations worldwide have begun to widely adopt agile software development practices, which offer greater flexibility to frequently changing business requirements, better cost effectiveness due to minimization of waste, faster time-to-market, and closer collaboration between business and IT. At the same time, IT services are continuing to be increasingly outsourced to third parties providing the organizations with the ability to focus on their core capabilities as well as to take advantage of better demand scalability, access to specialized skills, and cost benefits. An output-based pricing model, where the customers pay directly for the functionality that was delivered rather than the effort spent, is quickly becoming a new trend in IT outsourcing allowing to transfer the risk away from the customer while at the same time offering much better incentives for the supplier to optimize processes and improve efficiency, and consequently producing a true win-win outcome. Despite the widespread adoption of both agile practices and output-based outsourcing, there is little formal research available on how the two can be effectively combined in practice. Moreover, little practical guidance exists on how companies can measure the performance of their agile projects, which are being delivered in an output-based outsourced environment. This research attempted to shed light on this issue by developing a practical project monitoring framework which may be readily applied by organizations to monitor the performance of agile projects in an output-based outsourcing context, thus taking advantage of the combined benefits of such an arrangement Modified from action research approach, this research was divided into two cycles, each consisting of the Identification, Analysis, Verification, and Conclusion phases. During Cycle 1, a list of six Key Performance Indicators (KPIs) was proposed and accepted by the professionals in the studied multinational organization, which formed the core of the proposed framework and answered the first research sub-question of what needs to be measured. In Cycle 2, a more in-depth analysis was provided for each of the suggested Key Performance Indicators including the techniques for capturing, calculating, and evaluating the information provided by each KPI. In the course of Cycle 2, the second research sub-question was answered, clarifying how the data for each KPI needed to be measured, interpreted, and acted upon. Consequently, after two incremental research cycles, the primary research question was answered describing the practical framework that may be used for monitoring the performance of agile IT projects delivered in an output-based outsourcing context. This framework was evaluated by the professionals within the context of the studied organization and received positive feedback across all four evaluation criteria set forth in this research, including the low overhead of data collection, high value of provided information, ease of understandability of the metric dashboard, and high generalizability of the proposed framework.

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The purpose of this doctoral thesis is to widen and develop our theoretical frameworks for discussion and analyses of feedback practices in management accounting, particularly shedding light on its formal and informal aspects. The concept of feedback in management accounting has conventionally been analyzed within cybernetic control theory, in which feedback flows as a diagnostic or comparative loop between measurable outputs and pre-set goals (see e.g. Flamholtz et al. 1985; Flamholtz 1996, 1983), i.e. as a formal feedback loop. However, the everyday feedback practices in organizations are combinations of formal and informal elements. In addition to technique-driven feedback approaches (like budgets, measurement, and reward systems) we could also categorize social feedback practices that managers see relevant and effective in the pursuit of organizational control. While cybernetics or control theories successfully capture rational and measured aspects of organizational performance and offer a broad organizational context for the analysis, many individual and informal aspects remain vague and isolated. In order to discuss and make sense of the heterogeneous field of interpretations of formal and informal feedback, both in theory and practice, dichotomous approaches seem to be insufficient. Therefore, I suggest an analytical framework of formal and informal feedback with three dimensions (3D’s): source, time, and rule. Based on an abductive analysis of the theoretical and empirical findings from an interpretive case study around a business unit called Division Steelco, the 3Dframework and formal and informal feedback practices are further elaborated vis-á-vis the four thematic layers in the organizational control model by Flamholtz et al. (1985; Flamholtz 1996, 1983): core control system, organizational structure, organizational culture, and external environment. Various personal and cultural meanings given to the formal and informal feedback practices (“feedback as something”) create multidimensional interpretative contexts. Multidimensional frameworks aim to capture and better understand both the variety of interpretations and their implications to the functionality of feedback practices, important in interpretive research.

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Solanum glaucophyllum (Sg) [= S. malacoxylon] is a calcinogenic plant inducing "Enzootic Calcinosis" in cattle. The 1,25-dihydroxyvitamin D3, its main toxic principle, regulates bone and calcium metabolism and also exerts immunomodulatory effects. Thymocyte precursors from bone marrow-derived progenitor cells differentiate into mature T-cells. Differentiation of most T lymphocytes is characterized not only by the variable expression of CD4/CD8 receptor molecules and increased surface density of the T cell antigen receptor, but also by changes in the glycosylation pattern of cell surface glycolipids or glycoproteins. Thymocytes exert a feedback influence on thymic non-lymphoid cells. Sg-induced modifications on cattle thymus T-lymphocytes and on non-lymphoid cells were analysed. Heifers were divided into 5 groups (control, intoxicated with Sg during 15, 30 or 60 days, and probably recovered group). Histochemical, immunohistochemical, lectinhistochemical and morphometric techniques were used to characterize different cell populations of the experimental heifers. Sg-poisoned heifers showed a progressive cortical atrophy that was characterized using the peanut agglutinin (PNA) lectin that recognizes immature thymocytes. These animals also increased the amount of non-lymphoid cells per unit area detected with the Picrosirius technique, WGA and DBA lectins, and pancytokeratin and S-100 antibodies. The thymus atrophy found in intoxicated animals resembled that of the physiological aging process. A reversal effect on these changes was observed after suppression of the intoxication. These findings suggest that Sg-intoxication induces either directly, through the 1,25-dihydroxyvitamin D3 itself, or indirectly through the hypercalcemia, the observed alteration of the thymus.

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Myocardial contractility depends on several mechanisms such as coronary perfusion pressure (CPP) and flow as well as on a1-adrenoceptor stimulation. Both effects occur during the sympathetic stimulation mediated by norepinephrine. Norepinephrine increases force development in the heart and produces vasoconstriction increasing arterial pressure and, in turn, CPP. The contribution of each of these factors to the increase in myocardial performance needs to be clarified. Thus, in the present study we used two protocols: in the first we measured mean arterial pressure, left ventricular pressure and rate of rise of left ventricular pressure development in anesthetized rats (N = 10) submitted to phenylephrine (PE) stimulation before and after propranolol plus atropine treatment. These observations showed that in vivo a1-adrenergic stimulation increases left ventricular-developed pressure (P<0.05) together with arterial blood pressure (P<0.05). In the second protocol, we measured left ventricular isovolumic systolic pressure (ISP) and CPP in Langendorff constant flow-perfused hearts. The hearts (N = 7) were perfused with increasing flow rates under control conditions and PE or PE + nitroprusside (NP). Both CPP and ISP increased (P<0.01) as a function of flow. CPP changes were not affected by drug treatment but ISP increased (P<0.01). The largest ISP increase was obtained with PE + NP treatment (P<0.01). The results suggest that both mechanisms, i.e., direct stimulation of myocardial a1-adrenoceptors and increased flow, increased cardiac performance acting simultaneously and synergistically.