Design, analysis and implementation of voltage sensor for power-constrained systems

PhD ThesisThanks to an extensive effort by the global research community, the electronic technology has significantly matured over the last decade. This technology has enabled certain operations which humans could not otherwise easily perform. For instance, electronic systems can be used to perform sensing, monitoring and even control operations in environments such as outer space, underground, under the sea or even inside the human body. The main difficulty for electronics operating in these environments is access to a reliable and permanent source of energy. Using batteries as the immediate solution for this problem has helped to provide energy for limited periods of time; however, regular maintenance and replacement are required. Consequently, battery solutions fail wherever replacing them is not possible or operation for long periods is needed. For such cases, researchers have proposed harvesting ambient energy and converting it into an electrical form. An important issue with energy harvesters is that their operation and output power depend critically on the amount of energy they receive and because ambient energy often tends to be sporadic in nature, energy harvesters cannot produce stable or fixed levels of power all of the time. Therefore, electronic devices powered in this way must be capable of adapting their operation to the energy status of the harvester. To achieve this, information on the energy available for use is needed. This can be provided by a sensor capable of measuring voltage. However, stable and fixed voltage and time references are a prerequisite of most traditional voltage measurement devices, but these generally do not exist in energy harvesting environments. A further challenge is that such a sensor also needs to be powered by the energy harvester’s unstable voltage. In this thesis, the design of a reference-free voltage sensor, which can operate with a varying voltage source, is provided based on the capture of a portion of the total energy which is directly related to II the energy being sensed. This energy is then used to power a computation which quantifies captured energy over time, with the information directly generated as digital code. The sensor was fabricated in the 180 nm technology node and successfully tested by performing voltage measurements over the range 1.8 V to 0.8 V

Product Estimators for Hidden Markov Models

In this thesis, risk-sensitive estimation for Hidden Markov Models isstudied from a dynamical systems point of view. We show that risk-sensitive estimators belong to a broaderclass of product estimators in which risk-sensitivity willbe shown to be related to certain scaling functions.The product structureand the scaling functions perspective give us new insights into the underlying mechanism of risk-sensitive estimation.For the first time, in a series of theorems and examples, we relate risk-sensitivity to the dynamics of the underlying process and exposerelations among the transition probabilities, risk-sensitivity andthe decision regions. We introduce the risk-sensitive Maximum A Posterior Probability (MAP) criterion for HMM's with discrete rangeobservation. This criterion is the discrete time finite dimensionalversion of the classic risk-sensitive estimation problem for linear/quadratic partial observation case. The risk-sensitive filters take into account the"higher order" moments of the of the estimation error. In the context of risk-sensitive MAP for HMM's, we clarify and quantify the influence of risk-sensitivityon the behavior of the sample paths of the estimator; theproduct structure representationwill play an important role

Reliability and Makespan Optimization of Hardware Task Graphs in Partially Reconfigurable Platforms

This paper addresses the problem of reliability and makespan optimization of hardware task graphs in reconfigurable platforms by applying fault tolerance (FT) techniques to the running tasks based on the exploration of the Pareto set of solutions. In the presented solution, in contrast to the existing approaches in the literature, task graph scheduling, tasks parallelism, reconfiguration delay, and FT requirements are taken into account altogether. This paper first presents a model for hardware task graphs, task prefetch and scheduling, reconfigurable computer, and a fault model for reliability. Then, a mathematical model of an integer nonlinear multi-objective optimization problem is presented for improving the FT of hardware task graphs, scheduled in partially reconfigurable platforms. Experimental results show the positive impacts of choosing the FT techniques selected by the proposed solution, which is named Pareto-based. Thus, in comparison to nonfault-tolerant designs or other state-of-the-art FT approaches, without increasing makespan, about 850% mean time to failure (MTTF) improvement is achieved and, without degrading reliability, makespan is improved by 25%. In addition, experiments in fault-varying environments have demonstrated that the presented approach outperforms the existing state-of-the-art adaptive FT techniques in terms of both MTTF and makespan

The role of serotonin in memory: interactions with neurotransmitters and downstream signaling

Abstract Serotonin, or 5-hydroxytryptamine (5-HT), is found to be involved in many physiological or pathophysiological processes including cognitive function. Seven distinct receptors (5-HT1–7), each with several subpopulations, have been identified for serotonin, which are different in terms of localization and downstream signaling. Because of the development of selective agonists and antagonists for these receptors as well as transgenic animal models of cognitive disorders, our understanding of the role of serotonergic transmission in learning and memory has improved in recent years. A large body of evidence indicates the interplay between serotonergic transmission and other neurotransmitters including acetylcholine, dopamine, γ-aminobutyric acid (GABA) and glutamate, in the neurobiological control of learning and memory. In addition,there has been an alteration in the density of serotonergic receptors in aging and Alzheimer’s disease, and serotonin modulators are found to alter the process of amyloidogenesis and exert cognitive-enhancing properties. Here, we discuss the serotonin-induced modulation of various systems involved in mnesic function including cholinergic, dopaminergic, GABAergic, glutamatergic transmissions as well as amyloidogenesis and intracellular pathways

A case report of stomach and esophagus melanoma with liver metastases in a 63-year-old woman

BACKGROUND: Melanoma originates from melanocytes, which are dendritic pigmented cells. Malignant melanoma is divided into cutaneous and non-cutaneous types, and cutaneous one is the most common type. Gastric melanoma has rarely been reported, and is divided into primary and secondary categories.CASE REPORT: We report a 63-year-old woman with continues epigastric pain complaining of bloody defecation with elucidated blood, lack of appetite, weight loss, and icteric skin. She was a known case of hypertension, and a surgery of the left eye mass was done for her, which the patient's eye was discharged completely. The patient's biopsy sample was not sent for pathology, and there was no pathology result. The patient was evaluated with endoscopy because of epigastric pain of 6 months before. In addition to class A esophagitis, a nodule with an approximate dimension of 1 cm was seen in the Z-line of the esophagus, and two black lesions in the greater curvature of the stomach were seen, which biopsy of all these lesions was done. In the pathological study of biopsy specimens in a microscopic view, the replication of scattered hotspots in submucosa with atypical cells, large nuclei, and dark brown pigmentation were observed. In the immunohistochemistry study, HMB-25, Ki-67, carcinoembryonic antigen (CEA), and S100 were positive. Ultimately, the patient was diagnosed with melanoma.CONCLUSION: This report demonstrates the importance of medical documentation in determining the origin of diseases. as, if there was documentary evidence of the evacuated eye mass, differentiation of the primary or metastatic melanoma was possible