891 resultados para 230110 Calculus of Variations and Control Theory
Resumo:
Virtual machines (VMs) are powerful platforms for building agile datacenters and emerging cloud systems. However, resource management for a VM-based system is still a challenging task. First, the complexity of application workloads as well as the interference among competing workloads makes it difficult to understand their VMs’ resource demands for meeting their Quality of Service (QoS) targets; Second, the dynamics in the applications and system makes it also difficult to maintain the desired QoS target while the environment changes; Third, the transparency of virtualization presents a hurdle for guest-layer application and host-layer VM scheduler to cooperate and improve application QoS and system efficiency. This dissertation proposes to address the above challenges through fuzzy modeling and control theory based VM resource management. First, a fuzzy-logic-based nonlinear modeling approach is proposed to accurately capture a VM’s complex demands of multiple types of resources automatically online based on the observed workload and resource usages. Second, to enable fast adaption for resource management, the fuzzy modeling approach is integrated with a predictive-control-based controller to form a new Fuzzy Modeling Predictive Control (FMPC) approach which can quickly track the applications’ QoS targets and optimize the resource allocations under dynamic changes in the system. Finally, to address the limitations of black-box-based resource management solutions, a cross-layer optimization approach is proposed to enable cooperation between a VM’s host and guest layers and further improve the application QoS and resource usage efficiency. The above proposed approaches are prototyped and evaluated on a Xen-based virtualized system and evaluated with representative benchmarks including TPC-H, RUBiS, and TerraFly. The results demonstrate that the fuzzy-modeling-based approach improves the accuracy in resource prediction by up to 31.4% compared to conventional regression approaches. The FMPC approach substantially outperforms the traditional linear-model-based predictive control approach in meeting application QoS targets for an oversubscribed system. It is able to manage dynamic VM resource allocations and migrations for over 100 concurrent VMs across multiple hosts with good efficiency. Finally, the cross-layer optimization approach further improves the performance of a virtualized application by up to 40% when the resources are contended by dynamic workloads.
Resumo:
Historically, memory has been evaluated by examining how much is remembered, however a more recent conception of memory focuses on the accuracy of memories. When using this accuracy-oriented conception of memory, unlike with the quantity-oriented approach, memory does not always deteriorate over time. A possible explanation for this seemingly surprising finding lies in the metacognitive processes of monitoring and control. Use of these processes allows people to withhold responses of which they are unsure, or to adjust the precision of responses to a level that is broad enough to be correct. The ability to accurately report memories has implications for investigators who interview witnesses to crimes, and those who evaluate witness testimony. This research examined the amount of information provided, accuracy, and precision of responses provided during immediate and delayed interviews about a videotaped mock crime. The interview format was manipulated such that a single free narrative response was elicited, or a series of either yes/no or cued questions were asked. Instructions provided by the interviewer indicated to the participants that they should either stress being informative, or being accurate. The interviews were then transcribed and scored. Results indicate that accuracy rates remained stable and high after a one week delay. Compared to those interviewed immediately, after a delay participants provided less information and responses that were less precise. Participants in the free narrative condition were the most accurate. Participants in the cued questions condition provided the most precise responses. Participants in the yes/no questions condition were most likely to say “I don’t know”. The results indicate that people are able to monitor their memories and modify their reports to maintain high accuracy. When control over precision was not possible, such as in the yes/no condition, people said “I don’t know” to maintain accuracy. However when withholding responses and adjusting precision were both possible, people utilized both methods. It seems that concerns that memories reported after a long retention interval might be inaccurate are unfounded.
Resumo:
This chapter examines why policy decision-makers opt for command and control environmental regulation despite the availability of a plethora of market-based instruments which are more efficient and cost-effective. Interestingly, Sri Lanka has adopted a wholly command and control system, during both the pre and post liberalisation economic policies. This chapter first examines the merits and demerits of command and control and market-based approaches and then looks at Sri Lanka’s extensive environmental regulatory framework. The chapter then examines the likely reasons as to why the country has gone down the path of inflexible regulatory measures and has become entrenched in them. The various hypotheses are discussed and empirical evidence is provided. The chapter also discusses the consequences of an environmentally slack economy and policy implications stemming from adopting a wholly regulatory approach. The chapter concludes with a discussion of the main results.
Resumo:
A work-based professional development program was offered to a group of registered nurses working in palliative care. The goal of the program was to improve skills in psychosocial care (Yates et al., 1996). Participants were encouraged to reflect critically on their practice experience within a group setting. The focus of the group discussion and reflection were shared practice incidents. Each participant was given the opportunity to identify and describe an incident from their professional practice that presented a challenging issue within palliative nursing. This paper explores the themes of conflict and control, evident within the collection of fifteen practice incidents and discusses the nurses role as mediator. The concepts of patient advocacy and professional autonomy are challenged through the nurses experience of providing care within a hierarchical and bureaucratic health service. The outcome of reflection for the organization is most effective when shared experience and collective action (rather than individual practice) are the focus.
Resumo:
Throughout Australia (and in comparable urban contexts around the world) public spaces may be said to be under attack by developers and also attempts by civic authorities to regulate, restrict, rebrand and reframe them. A consequence of the increasingly security driven, privatised and surveilled nature of public space is the exclusion and displacement of those considered flawed and unwelcome in the ‘spectacular’ consumption spaces of many major urban centres. In the name of urban regeneration, processes of securitisation, ‘gentrification’ and creative cities discourses can refashion public space as sites of selective inclusion and exclusion. In this context of monitoring and control procedures, children and young people’s use of space in parks, neighbourhoods, shopping malls and streets is often viewed as a threat to the social order, requiring various forms of punitive and/or remedial action. This paper discusses developments in the surveillance, governance and control of public space used by children and young people in particular and the capacity for their displacement and marginality, diminishing their sense of place and belonging, and right to public space as an expression of their civil, political and social citizenship(s).
Resumo:
Throughout much of the world, urban and rural public spaces may be said to be under attack by property developers, commercial interests and also attempts by civic authorities to regulate, restrict, reframe and rebrand these spaces. A consequence of the increasingly security driven, privatised, commercial and surveilled nature of public space is the exclusion and displacement of those considered ‘flawed’ and unwelcome in the ‘spectacular’ consumption spaces of many major urban centres. In the name of urban regeneration, processes of securitisation, ‘gentrification’ and creative cities initiatives can act to refashion public space as sites of selective inclusion and exclusion. The use of surveillance and other control technologies as deployed in and around the UK ‘Riots’ of 2011 may help to promote and encourage a passing sense of personal safety and confidence in using public space. Through systems of social sorting, the same surveillance assemblages can also further the physical, emotional and psychological exclusion of certain groups and individuals, deemed to be both ‘out of time and out of place’ in major zones of urban, conspicuous, consumption. In this harsh environment of monitoring and control procedures, children and young people’s use of public spaces and places in parks, neighbourhoods, shopping malls and streets is often viewed as a threat to social order, requiring various forms of punitive and/or remedial action. Much of this civic action actively excludes some children and young people from participation and as a consequence, their trust in local processes and communities is eroded. This paper discusses worldwide developments in the surveillance, governance and control of the public space environments used by children and young people in particular and the capacity for their displacement and marginality, diminishing their sense of belonging, wellbeing and rights to public space as an expression of their social, political and civil citizenship(s).
Resumo:
Throughout Australia (and elsewhere in the world) public spaces are under attack by developers and also attempts by civic authorities to regulate, restrict and reframe them. A consequence of the increasingly security driven, privatised and surveilled nature of public space is the exclusion and displacement of those considered flawed and unwelcome in the “spectacular” consumption spaces of major urban centres. In this context of monitoring and control procedures, children and young people’s use of public space in parks, neighbourhoods, shopping malls and streets is often viewed as a threat to social order, requiring various forms of punitive and/or remedial action. This paper discusses developments in the surveillance, governance and control of public space used by children and young people in particular and the capacity for their displacement and marginality, diminishing their sense of belonging, wellbeing and right to public space as an expression of social, political and civil citizenship.
Resumo:
Objective: The purpose of the study was to examine the relationship of surveillance and control activities in Canadian hospitals with rates of nosocomial methicillin-resistant S. aureus (MRSA), C. difficile associated diarrhea (CDAD), and vancomycin-resistant Enterococcus (VRE). Methods: Surveys were sent to Infection Control programs in hospitals that participated in an earlier survey of infection control practices in Canadian acute care hospitals. Results: One hundred and twenty of 145 (82.8%) hospitals responded to the survey. The mean MRSA rate was 2.0 (SD 2.9) per 1,000 admissions, the mean CDAD rate was 3.8 (SD 4.3), and the mean VRE rate was 0.4 (SD 1.5). Multiple stepwise regression analysis found hospitals that reported infection rates by specific risk groups (r = - 0.27, p < 0.01) and that kept attendance records of infection control teaching activities (r = - 0.23, p < 0.01) were associated with lower MRSA rates. Multiple stepwise regression analysis found larger hospitals (r = 0.25, p < 0.01) and hospitals where infection control committees or staff had the direct authority to close a ward or unit to further admissions due to outbreaks (r = 0.22, p < 0.05) were associated with higher CDAD rates. Multiple logistic regression analysis found larger hospitals (OR = 1.6, CI 1.2 - 2.0, p = 0.003) and teaching hospitals (OR = 3.7, CI 1.2 - 11.8, p = 0.02) were associated with the presence of VRE. Hospitals were less likely to have VRE when infection control staff frequently contacted physicians and nurses for reports of new infections (OR = 0.5, CI 0.3 - 0.7, p = 0.02) and there were in-service programs for updating nursing and ancillary staff on current infection control practices (OR = 0.2, CI 0.1 - 0.7, p = 0.01). Conclusions: Surveillance and control activities were associated with MRSA and CDAD rates and the presence of VRE. Surveillance and control activities might be especially beneficial in large and teaching hospitals.
Resumo:
The purpose of this paper is to document the prevalent ownership concentration, structure and control in the top 100 companies listed on the Istanbul Stock Exchange. The results are discussed in the context of emerging corporate governance trends in Turkey. Where appropriate, comparisons with other countries are provided. The results of the study indicate that ownership of Turkish companies is highly concentrated, families being the dominant shareholders. The separation of ownership and control among Turkish companies is mainly achieved through pyramidal ownership structures and the presence of big business groups. However, the cash flow and voting rights in Turkish companies are relatively more aligned compared to other family–ownership–dominated insider–system countries.
Resumo:
This paper presents a practical algorithm for the simulation of interactive deformation in a 3D polygonal mesh model. The algorithm combines the conventional simulation of deformation using a spring-mass-damping model, solved by explicit numerical integration, with a set of heuristics to describe certain features of the transient behaviour, to increase the speed and stability of solution. In particular, this algorithm was designed to be used in the simulation of synthetic environments where it is necessary to model realistically, in real time, the effect on non-rigid surfaces being touched, pushed, pulled or squashed. Such objects can be solid or hollow, and have plastic, elastic or fabric-like properties. The algorithm is presented in an integrated form including collision detection and adaptive refinement so that it may be used in a self-contained way as part of a simulation loop to include human interface devices that capture data and render a realistic stereoscopic image in real time. The algorithm is designed to be used with polygonal mesh models representing complex topology, such as the human anatomy in a virtual-surgery training simulator. The paper evaluates the model behaviour qualitatively and then concludes with some examples of the use of the algorithm.
Resumo:
T1 tegumental antigen was isolated from a homogenate of eight- to 10-week-old Fasciola hepatica using a T1-specific monoclonal antibody bound to sepharose in an antibody-affinity column. Rats and mice were vaccinated with T1 antigen in Freund's complete adjuvant, and control groups received equivalent amounts of non-T1 antigen (eluted from the antibody-affinity column) or ovalbumin. On completion of the immunisation programme, serum samples were collected for ELISA and IFA testing. The animals were challenged by oral infection with F hepatica metacercariae or, for several vaccinated rats, by intraperitoneal transplantation of live adult flukes. At autopsy, worm-burden and liver damage was assessed for each animal and the condition of transplanted flukes was examined. Comparison of test and control groups of animals showed that neither T1 nor non-T1 antigens provided significant protection against challenge, although specific antibody responses against the appropriate sensitising antigen were engendered. Flukes transplanted to the peritoneal cavity of immunised rats survived without damage, although they became encased in hollow fibrous capsules of host origin. The results lend support to the pre-existing concept that glycocalyx turnover by discharge of T1 secretory bodies at the apical surface of migrating flukes provides an efficient means of protection for the parasite against host immunity.
Resumo:
Genetic chimeras made by aggregating early mouse embryos have many uses in developmental biology and have also provided insights into embryonic growth regulation. There is an indication that the embryo can regulate for an increase in size because although aggregation chimeras are twice as big as normal embryos when made, they are born of normal size. Upward regula..... tion of size reduced embryos is also possible. Half embryos made by the isolation or destruction of one of the blastomeres of a 2-cell embryo are also born of normal size. Little is known about the timing or the mechanism of this size regulation. In this study, the timing of size regulation in double and half embryos was clearly established by comparison of cell numbers derived from serial reconstruction of light microscope sections of control and experimental embryos. It was shown that size regulation in double embryos occurred around 6dl6h and in half embryos by 7dOh. Size regulation occurred in all tissues at the same time indicating a single control mechanism for the entire embryo. More detailed examination of the growth of double embryos revealed that size regulation occurred by alteration in cell cycle length~ No excessive cell death was found in double embryos compared to the controls and continuous labelling with [3H] thymidine showed no large non-dividing cell population in double embryos. However, a comparison of the mitotic index of double and control embryos after colcemid treatment, revealed a large difference between the two around 5dl6h to 6d16h. During this period, control embryos underwent a proliferative burst not shown by the double embryos. The mechanism for cell cycle control is not clear; it may be intrinsic to the embryo or determined by the uterine environment. Evidence was found suggesting that differentiation in the postimplantation embryo was cell number dependent. The timing of differentiative events was examined in half, double and control embryos. Proamnion formation, which occurs prior to size regulation, occurs at the same cell number but at different times in the three groups of embryos. However mesoderm which appears after size regulation was seen at the same time in all grollps of embryos.
Resumo:
There has been recent interest in using temporal difference learning methods to attack problems of prediction and control. While these algorithms have been brought to bear on many problems, they remain poorly understood. It is the purpose of this thesis to further explore these algorithms, presenting a framework for viewing them and raising a number of practical issues and exploring those issues in the context of several case studies. This includes applying the TD(lambda) algorithm to: 1) learning to play tic-tac-toe from the outcome of self-play and of play against a perfectly-playing opponent and 2) learning simple one-dimensional segmentation tasks.
Resumo:
Platelets are involved in the maintenance of haemostasis but their inappropriate activation leads to thrombosis, a principal trigger for heart attack and ischemic stroke. Although platelets circulate in isolation, upon activation they accumulate or aggregate together to form a thrombus, where they function in a coordinated manner to prevent loss of blood and control wound repair. Recent reports indicate that the stability and functions of a thrombus are maintained through sustained, contact dependent signalling between platelets. Given the role of gap junctions in the coordination of tissue responses, it was hypothesized that gap junctions may be present within a thrombus and mediate intercellular communication between platelets. Therefore studies were performed to explore the presence and functions of connexins in platelets. In this brief review, the roles of hemichannels and gap junctions in the control of thrombosis and haemostasis and the future directions for this research will be discussed.