Rozprawy doktorskie na temat „Disturbance”

My work explores domesticity, the role reversal happening in the family dynamics, the banality of home life, and the common escapism that occurs in parents. Men play a larger role in the home and women play a larger role outside the home blurring the lines of responsibility and changing expectations. This emasculating process often creates a power struggle within the home. These common issues are the fodder for my artistic practice. Domestic pattern, utility, sexual frustration, chaos and contentment all play a part.

Nowadays global companies view the world as a single entity, sourcing materials fromanywhere and performing operations to create the optimal supply chain for their products.This leads to an increasing complexity which is driving supply management to becomea core capability of businesses. As supply chains are inherently vulnerable to disturbances,supply management will have to play a key role in the field of risk analysisand risk management. An increased awareness of sources of disturbances is essential tocreate significant improvements in the handling and prevention of disturbances.The purpose of this thesis is to identify and classify sources of disturbance which canhave a negative influence on a company’s supply management. This is achieved by theinvestigation of theories available in literature, as well as identifying and analyzing thedisturbances in the supply management of an international manufacturing company.Additionally, the theories on disturbance management are reviewed to create a foundationfor managerial implications.The company studied is Husqvarna, which currently is in a situation with several disturbancesin its supply management. The performed case study aims at both, describingthese phenomena, as well as testing of the theories. The chosen qualitative approachmakes it possible to gain in-depth knowledge and investigate different aspects ofsources of disturbances in this case study. The interviews performed are standardizedopen ended questionnaires in order to get in-depth knowledge of the situation.The empirical findings are then analyzed in regard to the purpose of the thesis. The goalof this analysis is to compare the sources of disturbances of the classification schemecreated in the literature review to the respondents’ answers from the interviews. Moreover,inputs and opinions from the respondents on how to manage disturbances are connectedwith the theories provided in the literature review within this field.Various sources of disturbance with a negative influence on the supply management ofcompanies are identified. It was also possible to compare the classification schemewhich was created based on the theoretical findings with the finding of the case study ofHusqvarna. Consequently a holistic overview of potential and actual sources of disturbancein supply management has been created. Furthermore, it is possible to contribute tothe body of knowledge on how to manage disturbances in supply management. Theprovided insights highlight implications that can help companies to successfully managedisturbances and hence improve their performance.

Thesis (D.Eng.)--Cleveland State University, 2009.
Abstract. Title from PDF t.p. (viewed on Oct. 26, 2009). Includes bibliographical references (p. 78-89). Available online via the OhioLINK ETD Center and also available in print.

Thesis (Ph. D.)--University of Florida, 1999.
Title from first page of PDF file. Document formatted into pages; contains ix, 261 p.; also includes graphics. Vita. Includes bibliographical references (p. 248-260).

This thesis reviewed the major aetiological and treatment literature on infant sleep disturbance and concluded that the conceptual and methodological limitations of this literature have prevented progress in understanding the phenomenon. A model integrating the major findings of the literature was developed. The ethics of intervening to modify infant sleep disturbance were explored, in preparation for the experimental section. There were four separate studies. The first evaluated extinction as an intervention for infant sleep disturbance and found it effective in reducing all aspects of infant sleep disturbance. These reductions were still evident at three months and two years follow-up. This study contributes to the literature through its use of a systematic multiple baseline design, its inclusion of reliability assessment and by confining its consideration to the more uniform developmental stage of infancy, rather than including infants and pre-schoolers together. The second study evaluated two administration regimes for trimeprazine, a sedative widely prescribed for sleep disturbed infants in New Zealand. Trimeprazine increased the number of nights the infants slept through, however its effect was highly variable and in most cases not clinically significant. There was no evidence that use of the medication at either dose led to a lasting decrease in sleep disturbance. Study Two had the same strengths as Study One, and also contributes to the literature by its examination of a lower dose rate than any previously published study. Study Three compared extinction alone as a treatment, with extinction plus trimeprazine and extinction plus placebo. It aimed to establish whether the use of trimeprazine would lead to less infant distress, more infant security and less parental anxiety during treatment. There was some evidence that the use of the drug led to less infant distress, but an important finding was that infant security and maternal anxiety improved for all treated groups over time. This finding was important given some of the criticisms made against the use of extinction on ethical grounds. Study Four directly measured a wide range of infant behaviours in a group treated with extinction and two control groups. There was no evidence that extinction had any negative side effects and some evidence in fact, that it had positive side effects. This series of studies answered several important questions, particularly regarding the limitations of drug use and the efficacy and safety of extinction. The combination of these two treatments has provided another treatment alternative, particularly where parents are reluctant to use extinction. Several directions for future research were highlighted. These included not only the continued investigation of treatments for infant sleep disturbance, but also the factors determining whether a sleep disturbed infant presents for treatment and the effect of behavioural interventions on the development of infant sleep per se.

Body image, broadly defined as an individual's general experience of his or her physical appearance, is a multidimensional phenomenon that has been found to affect functioning throughout the lifetime. Although some degree of dissatisfaction has been found to be a common aspect of the female experience, research suggests that a disturbance in body image can result in a number of clinical complications, particularly the development of an eating disorder (ED). Despite the relationship between body image and EDs, examinations of the cognitive underpinnings of the relationship between body image disturbance and EDs are relatively few and inconclusive. Research indicates that individuals with an ED diagnosis exhibit cognitive rigidity (deficits in set-shifting ability) and weak central coherence(as demonstrated by performance on measures of information processing style). However, research has not established whether individuals with body image disturbance who do not meet criteria for an ED exhibit comparable performance. The aim of the current study was to determine whether individuals with body image disturbance exhibit similar patterns of neuropsychological functioning. A sample of women with high levels of body image disturbance completed a battery of cognitive tests and outcomes were compared to a group of women with little disturbance and also compared with performance of individuals with diagnosed EDs as cited in previous studies. Overall, the results do not clearly indicate that women with body image disturbance have difficulties with set-shifting tasks and global information processing, however some preliminary patterns did emerge. These preliminary findings extend existing theoretical models of body image and have potential to inform clinical efforts aimed at improving treatment protocols for body image disturbance and EDs by targeting these aspects of neurocognition during treatment.
Ph.D.
Department of Psychology
Sciences
Psychology PhD

Até há bem pouco tempo atrás, os Registradores de Perturbação utilizados em subestações de energia elétrica eram baseados em circuitos analógicos sendo a plotagem realizada através de Oscilógrafos que se utilizavam de papel foto-sensível ou gráfico. Como saída, estes equipamentos forneciam uma plotagem das formas de onda das tensões e correntes da pré-falta e da falta mas, no entanto, devido à tecnologia utilizada, não era possível se obter nem precisão das grandezas monitoradas (tensão ou corrente) nem informações sobre harmônicos presentes no sistema. Devido ao desenvolvimento de sistemas de aquisição de dados baseados em microprocessadores, novos Registradores de Perturbação (RP) têm sido desenvolvidos tendo como características: maior precisão na aquisição das grandezas; integração de funções de registros e cálculos variados; transferência de dados adquiridos via sistema de comunicação para os centros de análise; armazenamento dos dados em memória de massa (fita ou disco) para posterior manipulação matemática por computadores; sistemas de autodiagnóstico e automonitoramento para falhas em hardware e software, etc. Este trabalho se propõe apresentar alguns programas de pós- processamento que se utilizam dos dados adquiridos pelos RP, permitindo de uma forma rápida e de baixo custo informações como: tipo de falta ocorrida, componentes simétricas de seqüência positiva, negativa e zero; componentes harmônicas, a partir da análise espectral das grandezas adquiridas; localização da falta em LT`s, com indicação da distância do ponto de falta. Vários programas de teste foram desenvolvidos, além da utilização do EMTP (Electromagnectic Transient Program) e uma unidade de aquisição ARTUS para a comprovação dos algoritmos propostos.
Up until recently, disturbance recorder utilized in electric energy sub-stations were based on analog circuits and the plotting was done by oscilographs that utilized photo-sensitive paper or graph paper. As a result, these instruments provided a plotting of the kinds of waves of tensions and current of the pre-fault and of the fault. However, because of the technology that was used, it was not possible to get either precision of the monitored data (tension/current) or information about harmonic elements present in the system. Due to the development of data acquisition systems based on microprocessors, new disturbance recorders have been developed with the following characteristics: greater precision in acquisition of the data; integration of the functions of registers and various calculation; transfer of acquired data to the center of analysis through a communication system; storage of data in mass memory (tape or disc) for later mathematic manipulation by computer; systems of auto-diagnosis and auto-monitoring of hardware and software failures, etc. This work presents a few programs of post-processing that utilize data acquired by the disturbance recorder providing a fast, low-cost way to get information such as: the kind of failure that occurred; symmetrical components of positive, negative and zero sequences; harmonic components from the spectral analysis of the acquired data; localization of failures on LT`S, indicating the distance of the point of failure. Several test programs were developed to prove the proposed algorythms, including the utilization of EMTP (Electromagnectic Transient Program) and a unit of acquisition ARTUS.

This thesis explores the relationship between sound, word and image as mediated by technology. It is situated within the discipline of ‘performance art’ or ‘live art’ – both terms that I have come to challenge in my work because they fail to encompass the contemporary developments within this expanding field. My research pays particular attention to the technological conditions that affect contemporary performative practice. It investigates these conditions with special regard to the interrelated themes of improvisation, composition and exhibition, proposing constellations between performer, instrument, text and stage. This written component of my practice-based Ph.D follows the exhibition Melech at the Stanley Picker Gallery in January 2014, which brought together the key elements of my research over the course of four years. These manifested themselves as a triple-­‐screen video projection, a 45-­‐minute live performance, a photographic installation and the vinyl LP Melech. The following text focuses on the central working method of my practice, which I call the ‘sonic image’. I define the sonic image as an effect created when sound and gesture are added to words. My key area of investigation is the ‘instant feedback’ that occurs when the voice mediates text using technology. As a vocal performer working within a visual art context, my concern is with the sound of the spoken/sung word during a performance. During the course of my research I have developed the term ‘OpeRaArt’ to describe work that results from the performance of lyrical text. OpeRaart resonates with the Italian word opus (meaning ‘work’), ‘the opera’ being the performance constructed around the libretto (the opera’s text). In order to demonstrate the dynamic interaction of visual, sonic and semantic elements that govern the performance of language, I chose to make the spelling of the word OpeRaArt changeable – by shifting the capital letters. This reflects one of my major research findings: that visual, sonic and semantic elements have shifting statuses in the vocal delivery of words during a performance. Sometimes the visual element shapes/overrides the sonic, and at other times the sonic shapes/overrides the visual. The semantic element, rather than preceding sonic and visual elements as the ‘guarantor’ of the work’s content, is seen as developing from them. By making links between random fragments of language and signs, my research has enabled me to see how meaning can be generated without assuming that the sonic and the visual elements are directly answerable to a semantic one. Rather, the content surfaces through a constant migration between all three elements. 1920s and 1950s avant-­‐garde devices have strong links to methods and principles developed in my work. Although I consider these methods within their various historical contexts, I am primarily interested in their relation to the three axes of performance that dominate my method: improvisation, composition and exhibition. This triangulated way of thinking about performance guides the structure of my thinking, the thesis being concerned with how the core of an effective artwork will always involve oscillation between these three axes.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 69).
We have designed and built a Reluctance Actuator Gap Disturbance Testbed. The testbed emulates the short stroke and long stroke interaction of modern lithography stages. The testbed can be used to impart gap disturbance of the order of 10[mu]m to a target platten thereby providing a gap disturbance to the reluctance actuator. The testbed is equipped with three single-axis load cells that can measure a normal force, a roll torque and a pitch torque. We keep track of the orientation and position of the stage by using capacitance probes. The gap disturbance is imparted with three piezos capable of a stroke of 15[mu]m.We have also fabricated several reluctance actuators that fit into this testbed. These actuators use a two coil winding per core to prevent leakage and reduce stray torques. The cores of these actuators are made of Cobalt Iron, the soft magnetic material with the highest flux density saturation. Both a single actuator and a double actuator were fabricated. The double actuator can impart a roll torque as well as a normal force. Finite Element Method was utilized to design the actuators and to understand the nature of the rotational stiffness of the actuator. Experiments to do disturbance rejection were carried out and also different methods of force control (like Flux Feedback) are discussed and implemented
by Roberto J. Meléndez H.
S.M.

Forest biomass burned for energy purposes does not need to be accounted for under IPCC rules. This has led to a number of countries considering tree stump harvesting as a source of forest biomass. However there are concerns that the soil disturbance that this may entail could have adverse environmental effects, including the loss of sequestered carbon from the soil. Published results differ in the degree and nature of stump harvesting soil disturbance. Two widely used measures employed in stump harvesting soil disturbance studies are visual assessment of disturbance extent and bulk density measures of the nature of disturbance. Each of these has limitations. This study seeks to extend the insight into both the nature and extent of soil disturbance resulting from stump harvesting by the application of additional techniques. In this way the physical effects of soil disturbance by stump harvesting will be compared with those of other forestry practices. To overcome the two-dimensional and subjective nature of visual assessment, a radiometric approach was adopted, utilising residual Chernobyl 137Cs fallout to determine the degree of soil mixing. To complement bulk density measurements, micromorphological analyses of soil thin sections taken from field samples were carried out to investigate the impact of compressive force on pore space. Low-cost tracer devices were deployed in the soil around stumps prior to extraction to permit the monitoring of the lateral movement of soil during stump extraction. These methods were applied to a stump harvesting operation carried out under current UK guidance at a UPM Tilhill managed site in south west Scotland. The radiometric method demonstrated its capacity to recognise differing degrees of soil disturbance in an operational forest environment, including some disturbance that might escape visual assessment. Analysis of soil thin sections provided the evidence of a significant increase in the pore capacity of disturbed soil. The soil movement tracers developed for this project provided the capability to examine the various trajectories of soil during stump extraction as well as dimensioning the resulting disturbance crater. The study indicated that under current UK management and operational practice, stump harvesting generated a higher level of soil disturbance compared to ground preparation by trench mounding, with an estimated 1260 m3 ha-1 of soil disturbed by stump harvesting compared to 250 m3 ha-1 from trench mounding. Stump harvesting was found to generate a net reduction in soil bulk density in the affected areas, contrary to the findings of some other studies. This outcome is dependent on adhering to particular site management and operational procedures. The practice of raking over the site following stump harvesting is estimated to add a further 10% to the volume of soil disturbed, and is a questionable activity under soil sustainability guidance. This work was part-funded and actively supported by the UK Forestry Commission and UPM Tilhill.

Disturbance rejection is an important topic in control design since disturbances are inevitable in practical systems. To realise this target for nonlinear systems, this thesis brings in an assumption about the existence of a controlled invariant mani- fold and a Desired Feedforward Control (DFC) which is contained in the input to compensate the influence of disturbances. According to the approximation property of Neural Networks (NN) that any periodic signals defined in a compact set can be approximated by NN, the NN-based disturbance approximator is applied to approximate the DFC. Algorithmically, two important types of NN approximators that are Multi-layer Neural Networks (MNN) and Radial Basis Function Neural Networks (RBFNN) are presented in detail.In this thesis, a variety of nonlinear systems in standard canonical form are looked into. These forms are the output feedback form, the extended output feedback form, the decentralised output feedback form and the partial state feedback form. For these systems, four types of uncertainties are mainly considered. The first one is the disturbance that can be eliminated by the DFC. Secondly, the parameter uncertainty is taken into account. To get rid of this uncertainty, the adaptive control technique is employed for the estimation of unknown parameters, e.g. the NN gain matrix. The third one is the nonlinear uncertainty. For the case that nonlinear uncertainties are polynomials, it has a bound consisting of an unknown constant and a function of the regulated error such that this uncertainty can be also treated as the parameter uncertainty. Delay is the last type of uncertainty. Particularly, the delay is supposed to appear in output only. This uncertainty can be eliminated together with the nonlinear uncertainty. To establish the closed- loop stability, a Lyapunov-Krasovskii function is invoked. In addition, due to the requirement of the system structure or the stability analysis, some general control techniques are also involved such like the backstepping control and the high gain control.Throughout the results are illustrated by simulations.

Power system generators are interconnected in a distributed network to allow sharing of power. If one of the generators cannot meet the power demand, spare power is diverted from neighbouring generators. However, this approach also allows for propagation of electric disturbances. An oscillation arising from a disturbance at a given generator site will affect the normal operation of neighbouring generators and might cause them to fail. Hours of production time will be lost in the time it takes to restart the power plant. If the disturbance is detected early, appropriate control measures can be applied to ensure system stability. The aim of this study is to improve existing algorithms that estimate the oscillation parameters from acquired generator data to detect potentially dangerous power system disturbances. When disturbances occur in power systems (due to load changes or faults), damped oscillations (or "modes") are created. Modes which are heavily damped die out quickly and pose no threat to system stability. Lightly damped modes, by contrast, die out slowly and are more problematic. Of more concern still are "negatively damped" modes which grow exponentially with time and can ultimately cause the power system to fail. Widespread blackouts are then possible. To avert power system failures it is necessary to monitor the damping of the oscillating modes. This thesis proposes a number of damping estimation algorithms for this task. If the damping is found to be very small or even negative, then additional damping needs to be introduced via appropriate control strategies. This thesis presents a number of new algorithms for estimating the damping of modal oscillations in power systems. The first of these algorithms uses multiple orthogonal sliding windows along with least-squares techniques to estimate the modal damping. This algorithm produces results which are superior to those of earlier sliding window algorithms (that use only one pair of sliding windows to estimate the damping). The second algorithm uses a different modification of the standard sliding window damping estimation algorithm - the algorithm exploits the fact that the Signal to Noise Ratio (SNR) within the Fourier transform of practical power system signals is typically constant across a wide frequency range. Accordingly, damping estimates are obtained at a range of frequencies and then averaged. The third algorithm applied to power system analysis is based on optimal estimation theory. It is computationally efficient and gives optimal accuracy, at least for modes which are well separated in frequency.

Power system generators are interconnected in a distributed network to allow sharing of power. If one of the generators cannot meet the power demand, spare power is diverted from neighbouring generators. However, this approach also allows for propagation of electric disturbances. An oscillation arising from a disturbance at a given generator site will affect the normal operation of neighbouring generators and might cause them to fail. Hours of production time will be lost in the time it takes to restart the power plant. If the disturbance is detected early, appropriate control measures can be applied to ensure system stability. The aim of this study is to improve existing algorithms that estimate the oscillation parameters from acquired generator data to detect potentially dangerous power system disturbances. When disturbances occur in power systems (due to load changes or faults), damped oscillations (or "modes") are created. Modes which are heavily damped die out quickly and pose no threat to system stability. Lightly damped modes, by contrast, die out slowly and are more problematic. Of more concern still are "negatively damped" modes which grow exponentially with time and can ultimately cause the power system to fail. Widespread blackouts are then possible. To avert power system failures it is necessary to monitor the damping of the oscillating modes. This thesis proposes a number of damping estimation algorithms for this task. If the damping is found to be very small or even negative, then additional damping needs to be introduced via appropriate control strategies. This thesis presents a number of new algorithms for estimating the damping of modal oscillations in power systems. The first of these algorithms uses multiple orthogonal sliding windows along with least-squares techniques to estimate the modal damping. This algorithm produces results which are superior to those of earlier sliding window algorithms (that use only one pair of sliding windows to estimate the damping). The second algorithm uses a different modification of the standard sliding window damping estimation algorithm - the algorithm exploits the fact that the Signal to Noise Ratio (SNR) within the Fourier transform of practical power system signals is typically constant across a wide frequency range. Accordingly, damping estimates are obtained at a range of frequencies and then averaged. The third algorithm applied to power system analysis is based on optimal estimation theory. It is computationally efficient and gives optimal accuracy, at least for modes which are well separated in frequency.

Abstract Neurosensory disturbance is a common complication of bilateral sagittal split osteotomy (BSSO). This study focuses on the evaluation of factors affecting neurosensory disturbance after BSSO. Furthermore, the study focuses on the measurement of neurosensory disturbance with easily available bedside tests, not only on evaluating the state of sensory disturbance at each follow-up, but also on predicting the potential for recovery. Moreover, panoramic radiography, computerized tomography (CT) and conventional spiral tomography are assessed on locating the mandibular canal. The study was carried out involving a total of 50 patients undergoing BSSO for the correction of mandibular deficiency. In addition, 20 voluntary healthy students participated in this study. Questionnaires, a battery of neurosensory tests and preoperative imaging of the mandibular canal were used. A high incidence of neurosensory disturbance of the lower lip and chin was found after BSSO. However, recovery of sensation occurred with increasing frequency during the follow-up, and after one year sensation of the lower lip and chin returned to the presurgical situation in most patients. A prolonged neurosensory disturbance was more frequent in older patients, in large surgical movements of the mandible and in cases where the inferior alveolar nerve was manipulated during surgery. The bedside tests used in this study correlated well with the patients' subjective evaluation of neurosensory disturbance, and the repeatability of these tests was good. Furthermore, the sensibility testing of the mandibular teeth correlated well with the other tests and patient's subjective evaluation. Four days after surgery, sensibility testing of the mandibular teeth was an efficient test alone to predict the recovery from neurosensory disturbance. On radiographic imaging, the risk for neurosensory disturbance after BSSO could not be predicted from the panoramic radiograph. Before BSSO, CT was the best method to visualize the buccolingual location of the mandibular canal. After BSSO, a clinical follow-up using a battery of mechano- and nociceptive tests in the examination of sensation of the lower lip and chin, sensibility testing of the teeth, and subjective evaluation is needed. CT should be a part of treatment planning of the patients with thin rami or severe asymmetries of the mandible.

This thesis investigates how small disturbances influence community structure in three permanent pastures. Small disturbances play an important role in providing spatial heterogeneity that permits new recruits to enter populations in closed sward communities, thereby promoting diversity and species co-existence. The thesis has four components: the first two are based on observation and measurement of the occurrence of small disturbances, molehills and dung pats, in three pastures. Within pasture seasonal changes in disturbance regime were related to changes in patterns of species abundance by multidimensional contingency table analysis. Dactylis glomerata, Agropyron repens and Taraxacum officinale increased in highly disturbed plots, whereas Holcus lanatus and Trifolium repens decreased. Invasion of molehills and dung pats was usually by rhizomes or stolons from surrounding plants. Seedling recruitment was rare: Trifolium repens was the only species dependent on small gaps for sexual regeneration. Patterns of species replacement on and around the disturbances were non-random. The third part of the thesis investigated the effects of selective removal of Lolium perenne, Holcus lanatus and Trifolium repens from the oldest and youngest pastures. Strong responses to the removal of these species were found only in grasses in the youngest pasture. This is consistent with the hypothesis that competition decreases over time because of niche divergence, but may also reflect biological accommodation to grazing pressure. The fourth part of the thesis investigated changes in species composition in simulated swards in response to different regimes of mowing, fertilizer and small gap creation. Species composition was strongly influenced by mowing and fertilization but was unresponsive to small gap creation.
Science, Faculty of
Botany, Department of
Graduate

Thesis (M.S.)--West Virginia University, 2008.
Title from document title page. Document formatted into pages; contains viii, 70 p. : ill. Includes abstract. Includes bibliographical references (p. 37-45).

This study addresses violent urban disturbances which occurred in England in the early 1980s with particular reference to the Bristol ‘riots’ of April 1980 and the numerous disorders which followed in July 1981. Revisiting two concepts traditionally utilised to explain the spread of collective violence, namely ‘diffusion’ and ‘contagion,’ it argues that the latter offers a more useful model for understanding the above-mentioned events. Diffusion used in this context implies that such disturbances are independent of each other and occur randomly. It is associated with the concept of ‘copycat riots’, which were commonly invoked by the national media as a way of explaining the spread of urban disturbances in July 1981. Contagion by contrast holds that urban disturbances are related to one another and involve a variety of communication processes and rational collective decision-making. This implies that such events can only be fully understood if they are studied in terms of their local dynamics. Providing the first comprehensive macro-historical analysis of the disturbances of July 1981, this thesis utilises a range of quantitative techniques to argue that the temporal and spatial spread of the unrest exhibited patterns of contagion. These mini-waves of disorder located in several conurbations were precipitated by major disturbances in inner-city multi-ethnic areas. This contradicts more conventional explanations which credit the national media as the sole driver of riotous behaviour. The thesis then proceeds to offer a micro analysis of disturbances in Bristol in April 1980, incorporating both qualitative and quantitative techniques. Exploiting previously unexplored primary sources and recently collected oral histories from participants, it establishes detailed narratives of three related disturbances in the city. The anatomy of the individual incidents and local contagious effects are examined using spatial mapping, social network and ethnographic analyses. The results suggest that previously ignored educational, sub-cultural and ethnographic intra- and inter-community linkages were important factors in the spread of the disorders in Bristol. The case studies of the Bristol disorders are then used to illuminate our understanding of the processes at work during the July 1981 disturbances. It is argued that the latter events were essentially characterised by anti-police and anti-racist collective violence, which marked a momentary recomposition of working-class youth across ethnic divides.

Wind energy, like all renewable energy production, is a sustainable resource with a far lower carbon footprint than the burning of fossil fuels and consequently plays a role in mitigating climate change. There has been a rapid rise in its use over the last 15 years. However, there are concerns regarding the potential effects of wind turbines on wildlife, especially birds and bats. Potential effects include disturbance through direct or indirect habitat loss, or fatality through collision with turbine blades. First, I investigated the potential of using existing bird monitoring data collected by Environmental Impact Assessments (EIAs) and post-construction monitoring for developing an evidence base for the impacts of wind turbines on bird populations. As EIAs are required for wind farms to predict and mitigate potential negative effects, vast amounts of data are gathered by wind farm companies but subsequently not used to assess the effects, due to the associated logistical issues of obtaining these data (despite being officially available in the public domain). Using data from seven wind farm sites, I found that lekking black grouse (Tetrao tetrix) that were initially close to the wind turbines (up to 500m) moved locally after wind farm construction but their abundance at the wind farm sites did not change. I conclude that data from EIAs and post-construction monitoring can be used to assess potential effects of wind farms on biodiversity and should be widely available for scientists and policy-makers, ideally via a central data repository. Second, I investigated whether noise from wind farms might affect birds as bird song could be potentially masked. It is widely known that anthropogenic noise such as traffic and urban noise affects communication in birds. To investigate whether birds are affected by wind turbine noise, I modelled how song from iii birds propagates in a hypothetical environment with and without wind turbine noise. I found that songs from species where most of the energy lies in the lower frequencies are masked by wind turbine noise. As this model can predict potential disturbance effects for specific species, it could be used as a tool during EIAs by identifying which species will be affected by wind turbine noise. Third, as bird communication is masked by wind turbine noise, male-male, male-female and parent-offspring communication could be affected. I investigated if male-male interaction in European robins (Erithacus rubecula) is affected by wind turbine noise. Males responded less aggressively during simulated territorial intrusion with background wind turbine noise. This could lead to reduced breeding success as males might not be able to effectively defend their respective territories. Finally, I explored whether bioaoustic recorders could be used as a replacement for human wildlife surveys. Using the European nightjar (Caprimulgus europaeus) as an example, I found that survey methods using bioacoustic recorders are much more accurate and cheaper than surveys by humans. This could aid EIAs as they require wildlife surveys to determine which species might be affected by the development.

Traditionally, the southern botanists, facing much richer floras, dedicated their attention more to the disciplines of taxonomy and phytosociology. This created a detailed and extensive floristic knowledge on plant geographical distribution, poorly supported by an understanding of dynamic processes. This project was aimed to fill as much as possible of this lack of ecological approach in Mediterranean vegetation studies in Italy. The study area was located in the Campania region, southern Italy. The thesis programme was conceived as a series of investigations, starting with surveys and gradually narrowing down to specific experiments and analytical investigations. Site history is discussed as a key factor for the understanding of the regional variation of vegetation. Multivariate methods (Cluster Analysis, Principal Component Analysis) were used to analyse the vegetation composition data. They suggested that most observed changes of vegetation could reflect successional and degradation gradients rather than environmental differences. This view was supported by historical evidences of past-disturbance and dynamic processes, by study of ancient manuscripts, maps, paintings and photographs and by demographical data. The results of observations of both natural and experimental fires showed high ability to recover by vegetative sprouting and seed germination. Most fires were followed by 100&'37 survival with few exceptions in the case of the dry winter 1989 and of very hot fires. In these cases, Erica arborea was the most sensitive species. In contrast to fire, cutting depressed regrowth at one of the study sites located on most exposed and dry conditions. Recolonization after complete vegetation removal showed a different succession with an initial dominance of Dittrichia viscosa, later suppressed by Cistus spp. and Ampelodesmos mauritanicus. E.arborea did not recolonize after this kind of disturbance.

Loneliness is a risk factor for premature mortality but the mechanics of this relationship remain obscure. A potential mechanism is sleep disturbance. The present study aimed to examine the association between loneliness and sleep disturbance, evaluate loneliness as a risk factor for sleep disturbance and vice-versa, model effects between loneliness and sleep disturbance over time, and evaluate a mediation model of loneliness, sleep disturbance, and health. Data came from the 2006-2012 waves of the Health and Retirement Study, a nationally-representative study of older Americans; participants > 65 were included (n=11,400). Analyses included (i) linear regressions accounting for complex sampling and (ii) path analysis (cross-lagged panel and mediation models). Loneliness and sleep disturbance were correlated and were risk factors for one another. Cross-lagged panel models showed reciprocal effects between loneliness and sleep disturbance. Cross-lagged mediation models showed that loneliness predicted subsequent sleep disturbance, which in turn predicted poor self-reported health. Moreover, there was evidence of a direct and indirect effect of loneliness on sleep disturbance. All associations were weakened— but remained—when accounting for demographics, isolation, and depression. Collectively, these findings are consistent with the theory that sleep disturbance is a mechanism through which loneliness damages health. However, effects between loneliness and sleep are reciprocal, rather than unidirectional. Moreover, longitudinal effects were very small. Further research is necessary to speak to causality, assess daily associations between loneliness and sleep, assess a comprehensive model of the mechanics of loneliness and health, and examine loneliness and sleep in the context of other factors.

Questa ricerca ha avuto come oggetto di studio le modificazioni ecologiche indotte da un disturbo su vasta scala, analizzate a diversi livelli gerarchici di organizzazione biologica (individuo, popolazione, comunità, ecosistema). Lo scopo è stato quello di compararne l'importanza e considerare le risposte omeostatiche che conferiscono stabilità ai sistemi ecologici. Come fonte di disturbo ecologico è stata considerata l'attività di pesca demersale. A livello individuale, il processo di cattura dovuto all'azione di pesca è stato analizzato nei suoi componenti principali (danneggiamento fisico, esposizione all'aria, shock termico) considerando gli effetti singoli e sinergici rispetto ad una specie di crostaceo brachiuro Liocarcinus depurator, in termini di alterazioni metaboliche, stress a livello fisiologico, sopravvivenza ed eventuali modificazioni di alcuni moduli comportamentali (Capp. 2, 3, 4). I risultati hanno mostrato che l'esposizione all'aria ad elevate temperature determina i maggiori effetti su questo decapode, in quanto esso è adattato e diffuso in ambienti sublirtorali caratterizzati da fluttuazioni ambientali ridotte. A livello di popolazione la valutazione del danneggiamento fisico conseguente alle fasi di cattura e sorting a bordo dei pescherecci, è stata realizzata quantificando numero e tipologia delle appendici perdute, e confrontando i danneggi amenti cronici e quelli recenti in aree soggette a diverso sforzo di pesca (Ch. 5). Le analisi condotte hanno permesso di evidenziare una maggiore incidenza di danneggiamenti cronici nelle aree intensamente sfruttate. Nonostante l'elevata mortalità legata al disturbo della pesca, L. depurator è tuttora piuttosto diffuso anche in aree intensamente sfruttate. Tutto ciò è da porsi in relazione alla presenza di una sorta di "trade-off ' tra i costi energetici associati al disturbo della pesca (stress, mortalità, perdita di appendici, menomazione di alcune funzioni) ed i ridotti costi energetici di foraggiamento, associati alla capacità di questo brachiuro di nutrirsi degli organismi scartati dall'attività di pesca. Tutto ciò potrebbe rendere meno deleteri gli effetti del disturbo indotto dalla pesca conferendo una maggiore stabilità alle popolazioni disturbante. A livello intra-specifico, le caratteristiche strutturali e di stabilità dell'emocianina di L. depurator sono state considerate confrontando 7 differenti popolazioni provenienti dal mare Adriatico e dall'Oceano Atlantico Nord occidentale, mentre per un confronto inter-specifico sono state analizzate emocianine provenienti da 6 specie congeneri o appartenenti, comunque, alla famiglia dei Portunidi (Cap. 6) provenienti dalle medesime aree. I risultati hanno permesso di evidenziare una marcata eterogeneità sia a livello intra che interspecifico, che è stata messa in relazione all'ecologia delle specie (in termini di habitat occupati) ed alla variabilità ambientale delle diverse aree campionate. A livello di comunità bentonica, sono stati considerati gli aspetti funzionali in merito al processo di ricolonizzazione a seguito di un singolo evento di disturbo fisico. Le analisi sono state condotte comparativamente in due comunità del Nord Adriatico adottando uno schema sperimentale del tipo BACI ed esaminando i pattern relativi ad i principali gruppi trofici (Cap. 7). Il fenomeno di ricolonizzazione è guidato, nelle fasi iniziali, dagli "scavengers" potenziali in entrambi gli habitat, sebbene, come evidenziato mediante l'applicazione di indici termodinamici quali l'exergia, i processi coinvolti abbiano caratteristiche e tempistica sito-specifiche. Il confronto tra i siti sperimentali ed aree intensamente sfruttate contigue, ha permesso di verificare come l'intensa attività di pesca induca una riduzione della produzione e della biomassa della comunità bentonica. Gli effetti cronici dell'attività di pesca a livello di Nord Adriatico sono stati valutati comparando quantità e composizione dello scarto delle diverse attività di pesca a strascico durante il 2002 con dati storici relativi a campagne di monitoraggio della pesca e precedenti descrizioni delle comunità bentoniche (Cap. 8). Queste analisi hanno evidenziato fenomeni rilevanti quali la forte riduzione del rapporto scarto:commerciale, l'omogenizzazione della comunità bentonica e la scomparsa delle specie più vulnerabili (elevate dimensioni, crescita lenta). I risultati ottenuti hanno permesso infine di stimare in 25-35%, la frazione di produzione primaria del bacino Nord Adriatico necessaria per sostenere l'attività di pesca in tale bacino (Cap. 9). In conclusione, la ricerca realizzata ha permesso di descrivere come l'applicazione di un disturbo ecologico su vasta scala induca negli organismi delle risposte a livello individuale legate alle caratteristiche ecologiche delle specie ed alle peculiarità degli agenti di disturbo. I risultati conseguiti, hanno evidenziato come l'insieme delle relazioni dirette ed indirette influenzino le risposte dei livelli gerarchici superiori, mediante la comparsa di proprietà emergenti, quali la stabilità dinamica e le traiettorie dello sviluppo, determinando così la configurazione strutturale e funzionale delle comunità e dell'ecosistema nel suo complesso. This research focused on the effect of large-scale disturbance at several hierarchical levels of biological organisation (individual, population, community, ecosystem) and aimed to provide a comparison between the magnitude of the agents of disturbance and the homeostatic responses which confer stability on the ecological systems. Demersal fishing activity was considered as the source of ecological disturbance. At an individual level, the process of capture associated with fishing was analysed in its components (i.e. physical damage, exposure to air, thermal shock) taking into account both their individual and synergistic effects. Alterations in the metabolism and homeostatic capabilities, physiological stress, survival rates and the agonistic behaviour in the crustacean Brachyura Liocarcinus depurator were assessed (Ch. 2, 3, 4). Results highlighted that exposure to air at high temperatures during the sorting operations has the most detrimental effects on this decapod, due to the fact that L. depurator is a sublittoral species, adapted to rather stable environments. At a population level the sub-lethal injury frequencies, in terms of limbs lost resulting from the capture process, were assessed by comparing the level of chronic and recent damage (induced by the fishing activity itself) among different populations in the Northern Adriatic Sea (Ch. 5). Chronic damage was shown to be more frequent in the high fishing effort areas confirming a link with the trawl fishing activity. Notwithstanding the high damage and fishing mortality suffered in these areas, L. depurator revealed to be one of the dominant species, and this could be associated with a sort of trade-off between the high energetic costs payed by the populations due to the fishing activities (mortality, sub-lethal damages and subsequent function impairment) and the low costs associated to feeding on species discarded by the fishing activity. At an intra-specific level, the patterns of haemocyanin expression were compared among 7 populations of L. depurator from the Northern Adriatic Sea and the North West Atlantic Ocean. At an inter-specific level the haemocyanin stability of 6 species belonging to the same genus or family and collected in the same areas were carried out (Ch. 6). Results revealed an intra- and inter-specific structural variability in the sub-unit composition and stability of haemocyanins, which were to species ecology (habitat) and sampling sites environmental variability. At a community level, the shift from equilibrium and the recovery dynamics after a pulse disturbance were compared between two different benthic communities (mud and sand grounds) in the Northern Adriatic Sea, by adopting a BACI experimental scheme and paying special attention to the functional role of the trophic guilds (Ch. 7). In both habitats, the early successional stages of the recovery were driven by the potential scavengers even if, as highlighted by the application of the Exergy, some differences occurred in the patterns and timing of this process. The analyses of the benthic communities in heavily fished grounds allowed us to show that in these sites the intensive fishing activies induced a reduction in the benthic community biomass and production. At an ecosystem level, the chronic effects of fishing disturbance on the Northern Adriatic Sea were assessed by comparing the quantity and composition of the species discarded by different demersal fishing activities in 2002 to historical data from trawl surveys and the pre-existing benthic communities (Ch. 8). These analyses highlighted a steep reduction in the discard ratio (discarded catch:commercial catch) and the occurrence of a homogenisation of the benthic community and the depletion of highly vulnerable populations (large sized individuals, slow growth). The primary production required to sustain demersal fishery was estimated to be 25-35% of the total primary production of this area (Ch. 9). In conclusion, this research allowed us to show that large-scale ecological disturbance induces on organisms individual responses which depend both on the ecological features of the disturbed species and on the characteristics of the agents of disturbance. Results showed that the direct and the indirect relationshps determine the response of the higher hierarchical levels of organisation through emerging properties like their dynamic stability and development trajectories, thus determining the structure and functioning of the community and the ecosystem.

Karst environments are unique landscapes that contain important resources, including freshwater aquifers and specialized ecosystems, which are easily disturbed due to the interconnected nature of the surface and subsurface. The anthropogenic impacts on karst are deleterious to the ecosystems that are dependent on the karst environment and also to groundwater supplies. The Karst Disturbance Index (KDI) is a holistic tool used to measure anthropogenic impacts associated with karst environments, which has been applied and refined through studies performed in Florida and Italy, yet still remains untested and susceptible to modification for other areas. Application of the KDI in Arecibo, Puerto Rico, which is geographically isolated, and highly vulnerable due to its sensitive karst resources, provides an opportunity to test the index in an island setting. This research resulted in two KDI scores for the study area using both the original and recently modified methods. The scores reflect a significant to severe disturbance to the municipality’s karst environment of 0.54 and 0.68, respectively. Issues regarding the KDI were found from the application and comparison of these methodologies and revealed the need for adding additional indicators, including Mogote Removal and Coastal Karst, as well as several additional refinements and recommendations pertaining to scale, weighting, and incorporating the two methods together to create a single, more practical KDI tool. The disseminated results of the assessment of the area using the KDI will educate and help to foster stewardship of this vital resource in Puerto Rico.

During the last years, there has been an increase in the number and intensity of disturbances, and their consequences related with global change, which have corroborated the already forecasted scenarios. One example are wildfires, which are expected to increase both in intensity and extension in the near future. However, although the extensive research carried out to understand wildfire impacts, there is still a lack of knowledge regarding its consequences on freshwater temporary ponds. These temporary habitats constitute small biodiversity reservoirs, holding singular and iconic fauna. Nowadays, these habitats are endangered mostly due to habitat loss. Consequently, to cope with the future climatic scenario, which predicts an increase in wildfire disturbances as well as greater habitat loss, it becomes mandatory to better comprehend and study wildfire impacts on these small biodiversity jewels.Throghout this thesis I study the Jonquera wildfire consequences on the Albera temporary ponds
Durant els últims anys, l’increment de pertorbacions lligades al context de canvi global està corroborant cada dia els pronòstics més negatius. En aquesta mateixa línia, i en relació a les pertorbacions d’abast regional com els incendis, les prediccions no fan res més que pronosticar-ne un augment, tant en la intensitat com en l’extensió. Tanmateix, tot i la gran quantitat de recerca sobre els impactes dels incendis se sap poc en relació al seu impacte sobre els estanys temporanis d’aigua dolça. Aquests, constitueixen un reservori de biodiversitat únic i molt valuós en les regions com la Mediterrània i actualment es troben greument amenaçats a causa de la seva desaparició. En conseqüència, davant de les futures perspectives climàtiques d’increment dels incendis i d’una major pèrdua d’habitat, esdevé cabdal conèixer quins són els impactes dels incendis sobre els estanys temporanis mediterranis. En aquesta tesi s'aprofundeix en els afectes de l'incendi de la Jonquera sobre els estanys temporanis de l'Albera

Researchers and managers have sought for centuries to model the dynamics of river systems for hazard protection, water management, and ecological restoration. Models of channel dynamics generally assume that rivers adopt a constant geometry in response to a set of relatively static governing parameters. In this research, we develop two stochastic biogeomorphic models which we use to simulate the range of channel conditions associated with fluctuating governing conditions, including wood loading and discharge. We begin by developing a version of the Reach Scale Channel Simulator (RSCS) that models the impact of riparian disturbance on channel morphology at a range of channel scales, in a reach subject to an annual flood event of constant magnitude and duration. The simulations show that small- to intermediate-sized channels are the most morphologically sensitive to fluctuations in wood loading. We then develop a STochastic CHannel Adjustment SIMulator (STOCHASIM) that simulates the competition between bank erosion and vegetation colonization in a reach subject to variable annual floods. The model produces a dynamic channel geometry that adjusts in response to individual floods. The results challenge a major underlying assumption of most regime models by demonstrating that the return period of the formative flow varies with watershed hydrology. Introducing variable floods and lateral migration has important implications for wood loading, as bank erosion increases wood recruitment and changes piece characteristics. In the final chapters, we use data from a series of flume experiments to investigate the effects of piece characteristics on wood stability and transport. Rootwads -- which are more common on wood pieces recruited through bank erosion than via toppling -- increase piece stability while reducing travel distance. We use this research to further modify the RSCS model to account for wood inputs through bank erosion, as well as temporal changes in channel geometry and flood magnitude. When lateral mobility is considered, bank erosion inputs dominate wood loading while piece stability and morphologic impact decreases. As these stochastic models produce a range of channel conditions they are more likely to encompass the range of variability observed in natural systems than deterministic models of channel dynamics.
Arts, Faculty of
Graduate