We investigate in detail two multiuser opportunistic scheduling problems in centralized wireless systems: the scheduling of "delay-sensitive" flows with packet delay requirements of a few tens to few hundreds of milliseconds over the air interface, and the scheduling of "best-effort" flows with the objective of minimizing mean file transfer delay. Schedulers for delay-sensitive flows are characterized by a fundamental tradeoff between "maximizing total service rate by being opportunistic" and "balancing unequal queues (or delays) across users". In choosing how to realize this tradeoff in schedulers, our key premise is that "robustness" should be a primary design objective alongside performance. Different performance objectives -- mean packet delay, the tail of worst user's queue distribution, or that of the overall queue distribution -- result in remarkably different scheduling policies. Different design objectives and resulting schedulers are also not equally robust, which is important due to the uncertainty and variability in both the wireless environment and the traffic. The proposed class of schedulers offers low packet delays, less sensitivity to the scheduler parameters and channel characteristics, and a more graceful degradation of service in terms of the fraction of users meeting their delay requirements under transient overloads, when compared with other well-known schedulers. Schedulers for best-effort flows are characterized by a fundamental tradeoff between "maximizing the total service rate" and "prioritizing flows with short residual sizes". We characterize two regimes based on the "degree" of opportunistic gain present in the system. In the first regime -- where the opportunistic capacity of the system increases sharply with the number of users -- the use of residual flow-size information in scheduling will 'not' result in a significant reduction in flow-level delays. Whereas, in the second regime -- where the opportunistic capacity increases slowly with the number of users -- using flow-size information alongside channel state information 'may' result in a significant reduction. We then propose a class of schedulers which offers good performance in either regime, in terms of mean file transfer delays as well as probability of blocking for systems that enforce flow admission control. This thesis provides a comprehensive theoretical study of these fundamental tradeoffs for opportunistic schedulers, as well as an exploration of some of the practical ramifications to engineering wireless systems. / text

Glaucoma is an ophthalmic pathology that is the second leading cause of blindness. The laboratory design of a Polarization Sensitive Spectral Domain Optical Coherence Tomographic System aims to detect early glaucoma symptoms and prevent vision loss that occurs due to late or no glaucoma diagnosis. In order to perform human clinical trials at partner hospitals across the country, a miniaturized and portable version of the laboratory system was developed. The system facilitates easy transportation and clinical testing of the otherwise voluminous laboratory system across different eye centers. Significant consideration was given for performance optimization, cost reduction, design improvements and providing a friendly user-patient interface. / text

A large number of machine learning algorithms are critically dependent on the underlying distance/metric/similarity function. Learning an appropriate distance function is therefore crucial to the success of many methods. The class of distance functions that can be learned accurately is characterized by the amount and type of supervision available to the particular application. In this thesis, we explore a variety of such distance learning problems using different amounts/types of supervision and provide efficient and scalable algorithms to learn appropriate distance functions for each of these problems. First, we propose a generic regularized framework for Mahalanobis metric learning and prove that for a wide variety of regularization functions, metric learning can be used for efficiently learning a kernel function incorporating the available side-information. Furthermore, we provide a method for fast nearest neighbor search using the learned distance/kernel function. We show that a variety of existing metric learning methods are special cases of our general framework. Hence, our framework also provides a kernelization scheme and fast similarity search scheme for such methods. Second, we consider a variation of our standard metric learning framework where the side-information is incremental, streaming and cannot be stored. For this problem, we provide an efficient online metric learning algorithm that compares favorably to existing methods both theoretically and empirically. Next, we consider a contrasting scenario where the amount of supervision being provided is extremely small compared to the number of training points. For this problem, we consider two different modeling assumptions: 1) data lies on a low-dimensional linear subspace, 2) data lies on a low-dimensional non-linear manifold. The first assumption, in particular, leads to the problem of matrix rank minimization over polyhedral sets, which is a problem of immense interest in numerous fields including optimization, machine learning, computer vision, and control theory. We propose a novel online learning based optimization method for the rank minimization problem and provide provable approximation guarantees for it. The second assumption leads to our geometry-aware metric/kernel learning formulation, where we jointly model the metric/kernel over the data along with the underlying manifold. We provide an efficient alternating minimization algorithm for this problem and demonstrate its wide applicability and effectiveness by applying it to various machine learning tasks such as semi-supervised classification, colored dimensionality reduction, manifold alignment etc. Finally, we consider the task of learning distance functions under no supervision, which we cast as a problem of learning disparate clusterings of the data. To this end, we propose a discriminative approach and a generative model based approach and we provide efficient algorithms with convergence guarantees for both the approaches. / text

<p>Two new aspects of the dynamic behaviour in the audible frequency range of magneto-sensitive (MS) rubber are highlighted: the existence of an amplitude dependence of the shear modulus—referred to as the Fletcher–Gent effect—for even small displacements, and the appearance of large MS effects. These results have been obtained experimentally and are subsequently used to model two examples of magneto-sensitive rubber isolators to show how by means of MS rubber they can be improved. The first model calculates the transfer stiffness of a torsionally excited isolator and the second one the energy flow into the foundation for a bushing inserted between a vibrating mass and an infinite plate. In both examples notable improvements in isolation can be obtained</p>

Context-sensitive cognitive rehabilitation aims to address the specific deficits of patients by taking into account the unique strengths and weaknesses of each brain-injured individual. However, this approach requires customized assessments and trainings that are difficult to validate, time-consuming or simply unavailable for daily clinical use. Given the currently struggling economy and an increasing number of patients with brain injuries, a feasible and efficient solution for this individualized rehabilitation concept is needed. This dissertation addresses the development and evaluation of a VE-based training and assessment for context-sensitive cognitive rehabilitation. The proposed application is designed to closely resemble real-world places that are relevant to each individual neurological patient. Despite such an ecologically valid approach to rehabilitation, the application also integrates traditional process-specific tasks that offer potential for standardization and collection of normative data across patient populations. Three cognitive tasks (navigation, orientation, spatial memory) have been identified for use in individualized VEs. In three experimental trials the feasibility and validity of the technological implementation and theoretical foundation of these tasks has been assessed. In a fourth trial one of the tasks has been used for the rehabilitation of a brain-injured patient. Based on the results of these studies a workflow for the rapid development of VEs has been established which allows a VR developer to provide clinicians with individualized cognitive tasks. In addition, promising results for the clinical use and validation of the proposed system form the basis for future randomized controlled clinical trials. In conclusion, this dissertation elaborates how context-sensitive and process-specific rehabilitation approaches each offer a unique perspective on cognitive rehabilitation and how combining both through the means of VR technology may offer new opportunities to further this clinical discipline.

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Syftet var att undersöka högkänslighet och stress hos studenter. Metoden var en kvantitativ jämförande studie mellan grupper (kvinnor och män). Undersökningen genomfördes genom en elektronisk enkät. Urvalet var ett tillfällighetsurval av kvinnor och män i åldrarna 19 – 56 som studerade vid ett universitet, totalt 122 stycken deltagare, 31 män och 91 kvinnor. Deltagarna besvarade en enkät som bestod av bakgrundsfrågor och mätinstrument som mätte stress och högkänslighet. Resultatet visade på att högkänslighet och stress var skattad högst bland kvinnorna. Slutsatsen är att kvinnor och män skiljer sig i högkänslighet och stress samt att stress och högkänslighet korrelerar med varandra. / The aim was to investigate high sensitivity and stress among students. The method was a quantitative comparative study between groups (women and men). The survey was conducted through an electronic questionnaire. The selection was an opportunity sample of women and men who studied at a university and was between the ages of 19-56, a total of 122 participants 31 men and 91 women. The participants answered a questionnaire that consisted of background questions and instruments to measure stress and high sensitivity. The results showed that high sensitivity and stress was underestimated highest among women. The conclusion is that women and men differ in high sensitivity and stress, and that stress and high sensitivity correlate.

High salt intake contributes to the development of hypertension in salt-sensitive humans and animals and the mechanistic causes are poorly understood. In Dahl salt-sensitive (S) but not salt-resistant (R) rats, high salt diet increases cerebrospinal fluid (CSF) [Na+] and activates an aldosterone-mineralocorticoid receptor-epithelial sodium channel-endogenous ouabain (MR-ENaC-EO) neuromodulatory pathway in the brain that enhances the activity of sympatho-excitatory angiotensinergic and glutamatergic pathways, leading to an increase in sympathetic nerve activity (SNA) and blood pressure (BP). We hypothesize that high salt diet in Dahl S rats enhances Ang II release in the paraventricular nucleus (PVN), causing a decrease in local nitric oxide (NO) action and an increase in local glutamate release thereby elevating SNA, BP and heart rate (HR). The present study evaluated the effects of agonists or blockers of MR, ENaC, EO, nitric oxide synthase (NOS) or glutamate and AT1-receptors on the BP and HR responses to acute infusions of Na+ rich aCSF, intracerebroventricularly (icv), or in the PVN of Dahl S, R or Wistar rats or to high salt diet in Dahl S and R rats. In Wistar rats, aldosterone in the PVN enhanced the BP and HR responses to infusion of Na+ rich aCSF in the PVN, but not in the CSF, and only the enhancement was prevented by blockers of MR, ENaC and EO in the PVN. AT1-receptor blockers in the PVN fully blocked the enhancement by aldosterone and the responses to infusion of Na+ rich aCSF icv, or in the PVN. Na+ rich aCSF in the PVN caused larger increases in BP and HR in Dahl S vs. R rats and the responses to Na+ were fully blocked by an AT1-receptor blocker in the PVN. BP and HR responses to a NOS blocker in the PVN were the same, but L-NAME enhanced Na+ effects more in Dahl R than S rats. High salt diet attenuated increases in BP from L-NAME in the PVN of Dahl S but not R rats. AT1 and glutamate receptor blockers candesartan and kynurenate in the PVN decreased BP in Dahl S but not R rats on high salt diet. At the peak BP response to candesartan, kynurenate in the PVN further decreased BP whereas candesartan did not further decrease BP at the peak BP response to kynurenate. Our findings indicate that both an acute increase in CSF [Na+] and high salt intake in Dahl S rats increases AT1-receptor activation and decreases NO action in the PVN thereby contributing to the pressor responses to Na+ and presumably, to dietary salt-induced hypertension. The increased BP response to AT1-receptor activation in the PVN of Dahl S is mediated by enhanced local glutamate receptor activation. An MR-ENaC-EO pathway in the PVN can be functionally active and further studies need to assess its role in Dahl S rats on high salt intake.

Enhancing primary care is key to the Canadian health care reform. Considered as an indicator of primary care access and quality, hospitalisations for ambulatory care sensitive (ACS) conditions are commonly reported by Canadian organisations as sentinel events signaling problems with the delivery of primary care. However, the literature calls for further research to identify what lies behind ACS hospitalisation rates in regions with a predominantly urban population benefiting from universal access to health care. A theoretical model was built and, using an ecological design, multiple regressions were implemented to identify which neighbourhood characteristics explained the socio-economic gradient in ACS hospitalisation rates observed in Ottawa. Among these neighbourhoods, healthy behaviour and - to a certain extent - health status were significantly associated with ACS hospitalisation rates. Evidence of an association with primary care accessibility was also signaled for the more rural neighbourhoods. Smoking prevention and cessation campaigns may be the most relevant health care strategies to push forward by policy makers hoping to prevent ACS hospitalisations in Ottawa. From a health care equity perspective, targeting these campaigns to neighbourhoods of low socio-economic status may contribute to closing the gap in ACS hospitalisations described in this current study. Reducing the socio-economic inequalities of neighbourhoods would also contribute to health equity.

The integration of primary care and mental health care is a requirement of the Patient Protection and Affordable Care Act of 2010 and has challenged primary care providers to address gaps in the quality of care provided for patients with mental health issues. Vulnerable populations, such as the American Indian people experience gaps in quality health care, especially communication gaps and language barriers. This quality improvement project used a survey design to explore the potential for primary care providers to adopt a culturally sensitive electronic mental health, screening tool to bridge communication gaps and language barriers. Primary care providers recruited from the Northern Arizona University (NAU) Campus Health Services clinic evaluated the concept of a touch screen iPad technology to implement the Patient Health Questionnaire-9 (PHQ-9), which screens for depression using audio options in English and in the Navajo language to accommodate American Indian patients. A PowerPoint overview of the iPad technology was sent via email to the NAU providers and included; the PHQ-9 screening results, which are to be immediately accessible in the patient's electronic health record along with a screening report. The screening report included the PHQ-9 depression score, interpretation of the score, best treatment choices, and a graph for monitoring patient progress. This survey results concluded providers perceive the iPad technology for mental health screening to be useful in their integrated primary care clinic. A modified Technology Acceptance Model (Davis, 1989) was used to evaluate the providers' perception of the iPad Technology, and the University of Arizona's Qualtrics survey system provided data analysis of the survey results.