目的　本研究嚐試探討無望感與未來思考及情緒困擾間的關係，旨在驗證MacLeod的未來思考研究，以及區分病例組與對照組的敏感性。 研究對象　非病人樣本，主要為大學生以及部分社會人士，共123名；病人樣本則為台北巿立萬芳醫院的門診病患，共49名。 研究方法　非病人樣本採用隨機取樣，病人樣本採用隨機立意取樣之病例對照研究設計。 研究材料　包括「貝克無望感量表」、「貝克焦慮量表」、「貝克憂鬱量表第二版」、「語意歷程作業」、「語文流暢作業」、與「未來思考作業」共六項。 研究結果　本研究結果符合MacLeod先前的研究結果為，即(1)無望感與正向未來思考的減少有關；與(2)憂鬱與正向未來思考的減少，及負向未來思考的增加有關。不符合MacLeod的研究果為：焦慮與未來思考的關係不顯著。另外，以「正向未來思考」及「負向未來思考」來區分病人與非病人就目前的樣本而言，是不具有敏感性的。 結論　對於臨床工作而言，須注意正向未來思考減少對個案的影響，並進一步的給予適宜的處置，以預防疾病的再發。 關鍵字　無望感、正向未來思考、負向未來思考、情緒困擾

Plants are the major source of food or energy required to sustain life on the planet, but humans are grappling with the deteriorating conditions of natural ecosystems such as compositional change, desertification, invasive plants and soil erosion. In the face of global climate change and growing demands for agricultural productivity, future pressures on grassland ecosystems will intensify, therefore sustainable utilization of all plant resources is of vital importance to enhance food security within the limits of good conservation. The semi-arid grasslands of southern Africa represent major grassland resources for grazing. Herbage production in these areas is determined not only by water and nutrient availability, but also by controlled and uncontrolled fires. Since fire is regarded as a natural factor in savannas, it is essential to develop a deeper understanding of the role of fire in community structure and function for the development of appropriate burning regimes. A study was conducted in the Eastern Cape of South Africa where the rural communities are faced with the challenges of rangeland degradation in the form of encroachment by unacceptable bush, karroid, macchia and less desirable grass species, as well as soil erosion. The main objective of this thesis was to investigate the roles of competition and disturbance regimes (fire and simulated non-selective grazing) on species composition, habitat productivity and the performances of selected species from this semi-arid savanna. Long-term effects of burning frequency on herbaceous species composition, Leaf Area Index (LAI), Photosynthetically Active Radiation (PAR) within the herbaceous canopy, biomass production and soil chemical properties were investigated. These studies were conducted on a fire trial set up in 1980 at the University of Fort Hare research farm in the Eastern Cape, South Africa. The treatments comprise an annual, biennial, triennial, quadrennial, sexennial and no burn control, all replicated twice in a Complete Randomized Design. The data from the trial collected between 1980 and 2008 were used to determine compositional variation for herbaceous species using the Non-metric Multidimensional Scaling and Bray-Curtis Dissimilarity tests. The PAR ceptometer was used to determine LAI and intercepted PAR, while random samples were harvested from 1m² quadrats from each plot. Soil samples were taken at four depths (0-2 cm; 2-4 cm; 4-6 cm and 6-8 cm) from each plot and analyzed for pH, Ca, K, P, total C and total N. The Resin-Bag technique was used to determine nitrogen mineralization. Burning frequency caused significant variation in herbaceous species composition over time. The species were distributed along gradients of increasing burning frequency, and these responses were in three categories: Those that increased with burning frequency such as Themeda triandra; those that decreased with burning frequency such as Melica decumbens, and those that showed little response such as Panicum maximum. The three-year burn resulted in the highest compositional variation, light interception, Leaf Area Index, aboveground biomass production, while the annual, biennial and no burn treatments resulted in the lowest. The fact that infrequent burning resulted in higher species variation, improved habitat productivity due to increased leaf area for light interception shows that appropriate use of fire can maintain a more diverse and productive savanna system. Burning frequency had significant effects on the soil properties, while soil depth did not show any significance. Frequent burning increased soil pH, K, Ca, and Na, but reduced C, N, P and N mineralization. There was a negative correlation between burning frequency and N mineralization, but no correlation existed between N mineralization and total N, total C or the C:N ratio. These results imply that frequent burning can cause nutrient losses and a greater nutrient limitation to plants in the long-term, especially soil C and N loss from combustion of organic material in the soil top layer. The ability of shade-tolerant plants to persist under shade and regular defoliation such as in burnt and grazed systems may be of greater importance for long-term productivity and sustainability of forage crops. It is therefore imperative to explore the mechanisms by which some species were favoured by frequent burning which created low shade conditions, while others were favoured by high shade conditions where burning is infrequent or absent. A pot experiment was conducted to investigate the shade tolerances of seven grass species that were abundant in the long-term fire trial. The test species were Cymbopogon plurinodis, Digitaria eriantha, Eragrostis curvula, Melica decumbens, Panicum maximum, Sporobolus fimbriatus and Themeda triandra. Individual grass tillers of each species were collected from the natural vegetation, propagated in separate seedling trays and transplanted into individual pots, and were grown under five shading treatments: full sun (0 % shading), 55 %; 70 %; 85 % and 93 % shading respectively. Shading significantly reduced the dry matter production of all the species. Biomass production of all the species decreased linearly to varying degrees with an increase in shade intensity. Digitaria eriantha and Eragrostis curvula were most adversely affected by shading, hence are classified as shade intolerant, while Melica decumbens was the least affected by shading, and is hence classified as shade tolerant. Cymbopogon plurinodis, Panicum maximum, Sporobolus fimbriatus and Themeda triandra are classified as moderately shade-tolerant. From the results it was apparent that some species could perform optimally in partial shade than in full sunlight, and these results lead to a conclusion that for satisfactory natural regeneration and seedling growth of this savanna vegetation would require a gap large enough to provide at least 30 % of ambient light. Investigating patterns in competitive effects and responses of species in these communities may not only explain the abundance of each species, but may also provide insight into the nature of forces that affect the structure and function of that community. Since fire, herbivory and soil nutrients are natural drivers of savanna community structure and function, their influence on competitive interactions of selected species were investigated. Two experiments were conducted to investigate the competitive effects and responses of eight selected common species in the area. The test species (phytometers) included one woody shrub, Acacia karroo and seven grass species namely: Cymbopogon plurinodis, Digitaria eriantha, Eragrostis curvula, Melica decumbens, Panicum maximum, Sporobolus fimbriatus and Themeda triandra. In an outdoor plot experiment the responses of the phytometers to competition from neighbours (0; 2 and eight neighbours respectively), fertility (fertilized, unfertilized) and clipping (clipping, no clipping) were investigated. The second comprised a pot experiment where the competitive effects of the species were investigated. Each species was grown under 3 levels of fertility (0 %; 50 % and 100 % Hoagland‘s solution) and clipping (clipping, no clipping) in pots filled with fine river sand and 4 neighbours. Competition intensity, soil fertility and clipping had significant effects on the biomass production of the phytometer species. Acacia karroo and Melica decumbens, exhibited the weakest competitive effects and responses, and incurred the highest mortalities after clipping and with 8 neighbours. Digitaria eriantha and Panicum maximum exhibited the strongest competitive effects and responses, especially in high fertility, and experienced the lowest mortalities. T.triandra exhibited stronger competitive effect after clipping in low fertility, while A. karroo and C. plurinodis exhibited stronger competitive effects in moderate (50 %) fertility. Cymbopogon plurinodis, Eragrostis curvula and Sporobolus fimbriatus ranked between these two extreme groups in terms of competitive effects and responses. Relative Competitive Interaction increased with soil fertility and number of neighbours in the absence of clipping. These results indicate that in general, taller or broad-leaved grass species outgrow the shorter ones, and this gives them a competitive advantage over light and soil resources. One of the range management objectives in the False Thornveld of the Eastern Cape is to promote the abundance of Themeda triandra, which is of high forage value and an indicator of rangeland that is in good condition. The general situation under livestock farming conditions in this area is that if the grass sward is optimally grazed and rested then there is a great potential for Themeda triandra to dominate.The results of the competition experiments indicated that the species exhibits strong competitive interaction, and also exhibited stronger competitive effect after clipping in low fertility. These results imply that it has a low response and a high effect, an attribute that would enhance its performance if it is moderately grazed or the area is burnt. The species is also moderately shade tolerant, and this may explain why it thrives in burnt and moderately grazed areas. These studies have demonstrated the important role that competition and disturbance in the form of fire and herbivory play in the maintenance of this savanna grassland. Through natural selection species are able to occupy different niches in the same area and coexist in a heterogeneous environment and minimize their chances of extinction. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Research on aversive control of behaviour has dramatically declined over the past decades. This trend is primarily a consequence of an over-reliance on shock-based procedures, which have been increasingly criticized on ethical, practical, and ecological validity grounds. The continued study of aversive regulation thus requires the development of viable alternatives. Six preliminary experiments, triggered by serendipitous observations of Betta splendens’ reactions to unintended water disturbances, allowed for (a) developing a water flows (WFs) experimental paradigm; (b) confirming the aversive function of WFs; and (c) demonstrating the feasibility of the WFs paradigm as an alternative to the use of electric shock, as it does not involve painful stimulation and carries a higher level of inherent ecological validity. Based on the relevance of free-operant avoidance phenomena (Sidman, 1953a) for the study of aversive control, the fact that these have only been demonstrated in one fish species (goldfish) using shocks, and that the only attempt to show another form of avoidance in Betta splendens produced inconclusive results (Otis & Cerf, 1963), the WFs paradigm was implemented in two experiments aimed at addressing these issues. These studies were aligned with a research program on spatiotemporal analysis of behaviour that has demonstrated, over the course of several decades, that a comprehensive understanding of behavioural processes requires an approach that includes, but is not limited to, the study of rates of discrete responses (e.g., key pecks of a pigeon). Accordingly, a more holistic interpretation of experimental data than is typical for behavioural studies was attained through a combined analysis of the frequency and temporal distribution of a target response (crossings in a shuttle-tank), patterns of swimming trajectories, instances and durations of the aversive stimulus, and the occurrence of behaviour related to different features of the experimental tank. In Experiment 1, Betta splendens exposed to a free-operant avoidance procedure reliably escaped WFs but did not develop avoidance behaviour even though escape improved with practice. Moreover, adding a warning stimulus (curtains of air bubbles - CABs) to the free-operant procedure did not produce increments in avoidance behaviour, as has been demonstrated in other species. Considering these findings, Experiment 2 maintained the same free-operant avoidance contingencies, but escape responses were now scheduled to produce the WFs (punishment and extinction of escape). The result of this manipulation was not a substantial decrease of escape, but an initial large increase of this response, followed by a progressive decrease to approximately pre-punishment levels. In addition, punishment did not result in increased avoidance responding as an alternative response. The explanations for these unexpected findings relate to the duration of the CABs; sign- and goal-tracking effects; uncontrolled stimulation produced by water pump activation/operation; unintended reinforcement (mirror reflections and delay between the pump activation and WFs reaching full strength); and the development of responses that allowed the fish to reduce their exposure to high-intensity WFs (i.e., alternative behaviour). The need for investigating the effects of adjusting the WF procedures to the ecology and biology of Betta splendens is also discussed, particularly in regard to their territoriality and predominant defensive response (immobility) in relation to the experimental apparatuses and the target response (changing compartments).

Diss. (sammanfattning) Stockholm : Karolinska institutet 2006. / Härtill 4 uppsatser.

Thesis (Masters) -- The College of Saint Elizabeth, 2010. / Typescript. Available at The College of Saint Elizabeth - Office of Graduate Programs. "March 2010"

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This thesis addresses the problems of design and control of small cooperative unmanned autonomous quadrotor aerial vehicles. A new approach is proposed, for the modeling of the system’s dynamics using linearized Piecewise AffineModels. The Piecewise Affine dynamic–models cover a large part of the quadrotor’s flight envelope while also taking into account the additive effects of environmental disturbances. The effects of aerodynamic forces and moments were also examined. A small quadrotor is designed and developed that emphasizes in the areas of increased on–board computational capabilities, state estimation and modular connectivity. Based on the translational and rotational system’s dynamics: a) a switching model predictive controller, b) an explicitly solved constrained finite time optimal control strategy, and c) a cascade control scheme comprised of classical Proportional Integral Derivative control scheme augmented with angular acceleration feedback, were designed and experimentally tested in order to achieve trajectory tracking under the presence of wind–gusts. The efficiency of the proposed control methods was verified through extended experimental studies. The final quadrotor design utilizes a powerful control unit, a sensor system that provides state estimation based on inertial sensors, ultrasound sonars, GPS and vision chips, and an efficient actuating system. The research effort extended in the field of unmanned aerial vehicles cooperation. Cooperation strategies were proposed in order to address the problems of: a) Forest Fire Monitoring and b) Unknown Area Exploration and Target Acquisition. The Forest FireMonitoring algorithm is formulated based on consensus systems theory formulated as a spatiotemporal rendezvous problem in between the quadrotors. The Area Exploration and Target Acquisition algorithm is formulated based on market–based approaches. / Η συγκεκριμένη διατριβή καταπιάνεται με τα προβλήματα της σχεδίασης και ελέγχου μικρού μεγέθους συνεργαζόμενων μη επανδρωμένων αεροσκαφών με έμφαση στα συστήματα Κάθετης Απογείωσης και Προσγείωσης και ιδιαίτερα στη συστήματα τύπου Quadrotor. Μια νέα προσέγγιση για την μοντελοποίηση της δυναμικής του συστήματος η οποία βασίζεται στη θεωρία των Piecewise Affine συστημάτων προτείνεται. Η μοντελοποίηση με βάση τη θεωρία των Piecewise Affine συστημάτων καλύπτει ένα μεγάλο μέρος του φακέλου πτήσης του αεροσκάφους καθότι συνυπολογίζει μέρος της μη-γραμμικότητας του συστήματος ενώ παράλληλα δίνει τη δυνατότητα να χρησιμοποιηθούν τα ιδιαίτερα ανεπτυγμένα εργαλεία του γραμμικού ελέγχου. Αναπτύσσεται νέα πειραματική πλατφόρμα αεροσκάφους τύπου quadrotor η οποία χαρακτηρίζεται από ιδιαίτερες ικανότητες υπολογιστικής ισχύος, αυτόνομη εκτίμηση κατάστασης, πολλαπλή συνδεσιμότητα και αποδοτικό σύστημα πρόωσης. Η τελική πλατφόρμα quadrotor ελικοπτέρου UPATcopter ενσωματώνει μικρουπολογιστικό σύστημα υψηλών δυνατοτήτων, ειδικά συστήματα εκτίμησης κατάστασης τόσο σε εσωτερικούς όσο και σε εξωτερικούς χώρους μέρος των οποίων αναπτύχθηκε στα πλαίσια της διατριβής και αποδοτικό υποσύστημα πρόωσης. Τρεις διαφορετικοί νόμοι ελέγχου αναπτύχθηκαν και δοκιμάστηκαν πειραματικά. Αρχικά δοκιμάσθηκε ένας Constrained Finite Time Optimal Controller, ο οποίος υπολογίζεται πολύ-παραμετρικά και συνυπολογίζει την επίδραση των περιορισμών εισόδου και κατάστασης. Ο συγκεκριμένος ελεγκτής υπολογίσθηκε με βάση μια οικογένεια Piecewise Affine αναπαραστάσεων του υποσυστήματος προσανατολισμού και δοκιμάσθηκε επιτυγχάνοντας αποδοτικό έλεγχο του προσανατολισμού του σκάφους. Ακολούθως δοκιμάσθηκε ένας Switching Model Predictive Control βασισμένος στην Piecewise Affine μοντελοποίηση του συστήματος ο οποίος επίσης συνυπολογίζει την επίδραση των περιορισμών του συστήματος και του ρόλου των διαταραχών. Με τη χρήση αυτού του ελεγκτή επιτεύχθηκε έλεγχος προσανατολισμού και θέσης του αεροσκάφους τόσο σε άπνοια όσο και υπό την επίδραση ισχυρών διαταραχών ανέμου. Επιπρόσθετα, δοκιμάσθηκε ελεγκτής βασισμένος στη θεωρία PID ελέγχου επαυξημένος με ανάδραση γωνιακής επιτάχυνσης του συστήματος. Τέλος, η έρευνα επεκτάθηκε και στις στρατηγικές συνεργασίας μη επανδρωμένων αεροσκαφών προτείνοντας δύο αλγόριθμους. Συγκεκριμένα προτάθηκε αλγόριθμος για την αντιμετώπιση των προβλημάτων επιθεώρησης δασικής πυρκαγιάς και αλγόριθμος εξερεύνησης μιας άγνωστης περιοχής από ομάδα ετερογενών αεροσκαφών.

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Les travaux présentés dans cette thèse sont réalisés dans le cadre du projet européen ACCENT et s’inscrivent dans la problématique de l’utilisation de la surveillance d’usinage dans la fabrication des pièces critiques de moteurs aéronautiques. L’objectif est de définir une technique de surveillance de l’usure de l’outil dans l’usinage de l’alésage central d’un disque haute pression réalisé en superalliage à base nickel. Trois grandes étapes peuvent être identifiées dans notre démarche : l’identification des modes de dégradation dans le perçage de l’Udimet® 720 LI, la définition de relations entre les différents types d’usure et les grandeurs physiques mesurées et finalement, la proposition de stratégies de surveillance basées sur les résultats précédents. Afin de répondre aux objectifs, un protocole expérimental a été défini. Les campagnes expérimentales nous ont permis de caractériser l’usure du foret et de définir une cartographie des modes de dégradation en fonction de conditions de coupe testées. Par ailleurs, l’impact des perturbations d’usinage (coupure de lubrification, modification du pourcentage d’émulsion du lubrifiant, défaut de position de l’outil par rapport à l’avant-trou, etc.) a été étudié. La deuxième partie consiste à identifier les relations entre les modes de dégradation et les signaux de surveillance enregistrés (efforts, couple, puissance, vibrations, etc.). Pour cela, nous avons privilégié deux pistes : une explication directe de l’évolution des signaux par des phénomènes physiques et une approche selon « la base de données », pour développer des modèles d’usures par des critères statistiques extraits sur les signaux. Cette analyse a aussi permis la détection de certaines perturbations d’usinage en utilisant les grandeurs physiques mesurées. Il s’agit notamment d’un défaut d’excentration de l’outil dans le porte-outil et d’un problème d’évacuation de copeaux. La troisième étape porte sur la sensibilité des signaux afin de détecter l’ensemble des phénomènes et la définition des stratégies de surveillance pouvant être mises en œuvre. Pour chaque relation définie, nous avons déterminé une probabilité de détection. Ensuite, nous avons utilisé les signaux en parallèle afin d’accroitre la robustesse de la détection. Les taux de probabilité ont été améliorés, en se basant sur l’hypothèse d’indépendance des signaux (sans calculer les biais existants). Enfin, l’association de l’approche phénoménologique à l’approche dite « statistique » a permis d’augmenter la robustesse de la surveillance. / The work presented in this thesis is a part of European project ACCENT and fits into the context of using process monitoring in the manufacture of critical parts for aircraft engines. The aim is to define a monitoring technique for the tool wear in the machining of the central bore of a high pressure disk made in nickel based superalloy. The major stages can be identified in our approach: identification of tool failure modes in drilling Udimet® 720 LI, defining the relationships between wear and measured physical quantities and finally, a proposal for monitoring strategies based on the previous results. In order to complete the objectives, an experimental protocol was defined. The experimental campaigns allowed us to characterize the drill wear and to define cartography of tool failure modes depending on cutting conditions tested. Moreover, the impact of machining disturbances (lubricant stop, change in percentage of lubricant emulsion, the position over the before hole, etc.) was studied. In the second part, the relations between the tool failure modes and monitoring signals recorded during the machining (forces, torque, power, vibrations, etc.) were identified. For this task, we focused on two directions: a straightforward explanation of signals evolution by physical phenomena and “black box” approach to develop wear models from a database obtained by statistical criteria extracts from the signals. This analysis also allowed the detection of certain machining disturbances using the physical quantities. These include an eccentricity of the tool in the tool holder and a chips evacuation problem. The third part concerns the signals sensitivity to detect the different phenomena and the definition of monitoring strategies which can be implemented. For each relation defined, a detection probability was determined. Further, we used signals in parallel to increase the robustness of detection. The probabilities were improved, with an assumption of independent signals (without calculating existing biases). Finally, the combination of the phenomenological approach to the so-called "statistical" has increased the robustness of the monitoring technique.