The design of active resistors and transductors in a CMOS technology

Merged with duplicate record 10026.1/2618 on 07.20.2017 by CS (TIS)This thesis surveys linearisation techniques for implementing monolithic MOS active resistors and transconductors, and investigates the design of linear tunable resistors and transconductors. Improving linearity and tunability in the presence of non-ideal factors such as bulk modulation, mobility-degradation effects and mismatch of transistors is a principal objective. A family of new non-saturation-mode resistors and two novel saturation-mode transconductors are developed. Where possible, approximate analytical expressions are derived to explain the principles of operation. Performance comparisons of the new structures are made with other well-known circuits and their relative advantages and disadvantages evaluated. Experimental and simulation results are presented which validate the proposed linearisation techniques. It is shown that the proposed family of resistors offers improved linearity whilst the transconductors combine extended tunability with low distortion. Continuous-time filter examples are given to demonstrate the potential of these circuits for application in analogue signal-processing tasks.GEC Plessey Semiconductors, Plymout

Appetite regulation by leptin

Obesity is a prevalent problem in modern society, which requires the upmost attention in the biomedical sciences. A leading cause of obesity related diseases is due to overeating, especially in industrialized countries. Leptin is the hormone that is secreted by fat cells responsible for communicating body nutritional status to the brain. Leptin interacts with other bodily systems such as the cognitive, digestive, neuronal, and endocrine systems. Leptin acts mainly on the Ob-Rb receptor in the arcuate nucleus of the hypothalamus and largely suppresses food intake and increases energy expenditure by activating Proopiomelanocortin and Cocaine- and amphetamine-regulated transcript (anorexigenic signals) neurons and by suppressing Neuropeptide Y and Agouti-related peptide (orexigenic signals) neurons, among other chemical signaling pathways. In both rodent and human studies, exogenous leptin administration resulted in elevated plasma leptin concentrations. When researchers tried to use leptin for weight reducing medical treatments in humans, the results show difficulty in establishing clinical efficacy. However, for diseases such as congenital leptin deficiency, obesity related leptin resistance, and lipodystrophy, medical treatments involving exogenous leptin have been relatively successful. The goal of this thesis is to give readers an understanding of leptin’s role in regulating appetite and the different leptin associated diseases. Leptin’s role is still continuing to be developed and more research is needed to fully utilize leptin for therapeutic benefit

Molecular detection of minimal residual disease for patients with leukemia and lymphoma

Although a complete clinical remission can often be achieved with chemotherapy for patients with leukaemia and lymphoma, relapses still occur. Residual tumour cells probably have survived therapy and account for subsequent disease relapse. The sensitivity of conventioned ways of detecting residual tumour cells, such as morphological studies, immunophenotyping, and cytogenetics, is only about 1% to 5% and may be inadequate. Polymerase chain reaction technology had provided a simple and highly sensitive means for the detection of minimal residual disease. The technology has been successfully applied to study biopsy samples obtained from patients with leukaemia and lymphpma. Its clinical usefulness, however, requires further evaluation by prospective clinical studies.published_or_final_versio

Modeling of epoxy dispensing process using a hybrid fuzzy regression approach

In the semiconductor manufacturing industry, epoxy dispensing is a popular process commonly used in die bonding as well as in microchip encapsulation for electronic packaging. Modeling the epoxy dispensing process is important because it enables us to understand the process behavior, as well as determine the optimum operating conditions of the process for a high yield, low cost, and robust operation. Previous studies of epoxy dispensing have mainly focused on the development of analytical models. However, an analytical model for epoxy dispensing is difficult to develop because of its complex behavior and high degree of uncertainty associated with the process in a real-world environment. Previous studies of modeling the epoxy dispensing process have not addressed the development of explicit models involving high-order and interaction terms, as well as fuzziness between process parameters. In this paper, a hybrid fuzzy regression (HFR) method integrating fuzzy regression with genetic programming is proposed to make up the deficiency. Two process models are generated for the two quality characteristics of the process, encapsulation weight and encapsulation thickness based on the HFR, respectively. Validation tests are performed. The performance of the models developed based on the HFR outperforms the performance of those based on statistical regression and fuzzy regression

Creating interaction in online learning: a case study

This paper uses the case‐study method to examine detailed data related to student and tutor usage of an asynchronous discussion board as an interactive communication forum during a first‐semester associate degree course in applied psychology at the City University of Hong Kong. The paper identifies ‘what works’ in relation to discussion board use, demonstrating how students might gradually create an online community of their own, but only if prompted in a timely and appropriate way by the course structure. It also identifies three distinct phases in online interaction and suggests these might, to some extent, be mediated by assessment tasks

Neuroprotection and acidosis induced by cortical spreading depression

We read with interest the article “Cortical spreading depression produces a neuroprotective effect activating mitochondrial uncoupling protein-5” published in Neuropsychiatr Dis Treat by Viggiano et al.1 The authors showed that cerebral spreading depression (CSD) triggered uncoupling protein-5 (UCP-5),1 which had been reported to exert a long-term effect upon neuron protection.2 The result is another piece in CSD literature on modifying gene expressions to provide neuroprotection to subsequent ischemic episodes.3,

Susceptibility of the upper respiratory tract to influenza virus infection following desialyation

Conference Theme: Translating Health Research into Policy and Practice for Health of the PopulationPoster Presentations - Emerging / Infectious Diseases: no. P132-Ab0100BACKGROUND: Influenza infection begins with the attachment of the viral haemagglutinin (HA) to the surface receptor of a cell. This binding involves a glycan called sialic acid (Sia). Previous studies have suggested that the affinity of influenza viruses isolated from different species depends on the linkage between this Sia and the adjacent sugar (usually galactose). In general, human and swine viruses prefer Sia with an α2-6 linkage while avian viruses prefer an α2-3 linkage. Though there are commercially available therapies that block influenza virus release, there has been limited information on controlling influenza virus infection by …published_or_final_versio