High-throughput technologies for rapid measurement of vast numbers of biolog- ical variables offer the potential for highly discriminatory diagnosis and prognosis; however, high dimensionality together with small samples creates the need for fea- ture selection, while at the same time making feature-selection algorithms less reliable. Feature selection is required to avoid overfitting, and the combinatorial nature of the problem demands a suboptimal feature-selection algorithm. In this dissertation, we have found that feature selection is problematic in small- sample settings via three different approaches. First we examined the feature-ranking performance of several kinds of error estimators for different classification rules, by considering all feature subsets and using 2 measures of performance. The results show that their ranking is strongly affected by inaccurate error estimation. Secondly, since enumerating all feature subsets is computationally impossible in practice, a suboptimal feature-selection algorithm is often employed to find from a large set of potential features a small subset with which to classify the samples. If error estimation is required for a feature-selection algorithm, then the impact of error estimation can be greater than the choice of algorithm. Lastly, we took a regression approach by comparing the classification errors for the optimal feature sets and the errors for the feature sets found by feature-selection algorithms. Our study shows that it is unlikely that feature selection will yield a feature set whose error is close to that of the optimal feature set, and the inability to find a good feature set should not lead to the conclusion that good feature sets do not exist.

The digital product increases widely and vastly. We need a converter to change analog signal to digital one. However, the requirement of analog-to-digital converter is rising due to progress of DSP (Digital Signal Processor). In most ADC structure there have an important building block called the front-end sample-and-hold circuit (SHA) . I will design and implement a high speed and low power sample and hold circuit. In this thesis, the circuits are designed with UMC 90nm 1P9M CMOS process and 1.2V of supply voltage. The speed and resolution of SHA are 100Ms/s and 10bits individually. The circuit is implemented with class AB amplifier.

Over the past decades, bulk metallic glasses (BMGs) have attracted extensive interests because of their unique properties such as good corrosion resistance, large elastic limit, as well as high strength and hardness. However, with the advent of micro-electro-mechanical systems (MEMS) and other microscaled devices, the fundamental properties of micrometer-sized BMGs have become increasingly more important. Thus, in this study, a methodology for performing uniaxial compression tests on BMGs having micron-sized dimensions is presented. Micropillar with diameters of 3.8, 1 and 0.7 £gm are fabricated successfully from the Mg65Cu25Gd10 and Zr63.8Ni16.2Cu15Al5 BMGs using focus ion beam, and then tested in microcompression at room temperature and strain rates from 1 x 10-4 to 1 x 10-2 s-1. Microcompression tests on the Mg- and Zr-based BMG pillar samples have shown an obvious sample size effect, with the yield strength increasing with decreasing sample diameter. The strength increase can be rationalized by the Weibull statistics for brittle materials, and the Weibull moduli of the Mg- and Zr-based BMGs are estimated to be about 35 and 60, respectively. The higher Weibull modulus of the Zr-based BMG is consistent with the more ductile nature of this system. In additions, high temperature microcompression tests are performed to investigate the deformation behavior of micron-sized Au49Ag5.5Pd2.3Cu26.9Si16.3 BMG pillar samples from room to their glass transition temperature (~400 K). For the 1 £gm Au-based BMG pillars, a transition from inhomogeneous flow to homogeneous flow is clearly observed at or near the glass transition temperature. Specifically, the flow transition temperature is about 393 K atthe strain rate of 1 x 10-2 s-1. For the 3.8 £gm Au-based BMG pillars, in order to investigate the homogeneous deformation behavior, microcompression tests are performed at 395.9-401.2 K. The strength is observed to decrease with increasing temperature and decreasing strain rate. Plastic flow behavior can be described by a shear transition zone model. The activation energy and the size of the basic flow unit are deduced and compared favorably with the theory.

When assessing preferences of individuals with developmental disabilities, choices can be described vocally or presented using objects or pictures in preference assessments. For individuals who are unable to perform auditory-visual discriminations and visual identity matching, objects instead of pictures or vocalizations need to be used for preference assessments to be effective. Considering the practical advantages of using pictures over objects, recent research has begun to focus on identifying and teaching skills needed for picture preference assessments. Although object-to-picture, picture-to-object, and generalized matching have been implicated as possible skills needed for picture preference assessments, further systematic studies are needed. The present study examined the relation between preference assessments (object vs. picture groups) and 5 discrimination skills. Based on direct paired-stimulus preference assessments completed at the beginning of the study, participants who could indicate their preferences with objects, but not with picture or vocal presentation, were assigned to the Object Group (n = 11); and participants who could indicate their preferences with both objects and pictures, but not vocal presentation, were assigned to the Picture Group (n = 9). The 5 discrimination tasks included: (a) object-picture matching and (b) its symmetry, picture-object matching; (c) generalized object-picture matching and (d) its symmetry, generalized picture-object matching; and (e) generalized identity picture-picture matching. All task stimuli were parts from everyday objects. Independent sample t-tests with Bonferroni correction showed that the percentages of correct responses were significantly higher in the Picture Group than in the Object Group on 4 of the 5 tasks (p < .01). Individual data showed that 8 of the 9 Picture Group participants met the pass criterion (80% or higher correct responses) on at least 1 discrimination task, with 6 participants passing 2 or more tasks. In contrast, only 1 of the 11 Object Group participants met the pass criterion on 1 discrimination task. The findings suggest that the effectiveness of picture preference assessments is not dependent on one specific discrimination, but possibly the ability to perform generalized matching.

Tedlar™ bags are a promising medium for remote breath collection and later analysis using SIFT-MS for disease diagnosis. It is important to understand the changes in integrity of samples stored in Tedlar™ bags. However, there is little work into this problem completed to date, and thus little known about these issues. Therefore, a study into the integrity of samples stored in Tedlar™ bags and analysed using SIFT-MS was undertaken. The sample integrity of ammonia, acetone, ethanol, isoprene and pentane, all initially at 3ppm in breath and nitrogen substrates, and stored in Tedlar™ bags was investigated. Experiments tested the effect of storage size (0.5, 1, 3L), storage time (6-48 hours), storage temperature (23℃ - 25℃, 37℃), humidity (0.4 - 4.5% absolute) and inter-bag variation using triplicate bags. The SIFT-MS instrument used was LDI2 located at Christchurch Hospital. The repeatability and precision of LDI2 was established using prepared cylinder samples (0.05% absolute humidity) of acetone, pentane and ethanol tested at seven times over a 250 min time period. A generalised Cauchy distribution was used to give a combined distribution from multiple bags for the sample humidity and compound concentration. A combined measure of the repeatability and precision, T s , ranged between 217 - 349 ppb for ethanol, acetone and pentane. The factors affecting the repeatability and precision were both machine and compound dependant. The effect of the factors differed over time, with different precursors and compounds. No obvious effects of bag storage size on the sample integrity of pentane, isoprene, ethanol and acetone were observed. The absolute humidity change within bag samples was linked to the volume to surface area ratio because it was more affected by permeation and condensation. All compounds in the nitrogen substrate (except for 37℃ stored acetone (NO+)) displayed decreases in sample integrity with time. All compounds in the breath substrate displayed regular losses of sample integrity, except for the 37℃ and 23℃ - 25℃ stored ethanol (NO+) and 37℃ stored ethanol (H3O+), pentane (O2+) and ammonia (H3O+, O2+). The average change of sample integrity for pentane, isoprene, ethanol and acetone ranged from 0.2 to 3.6 times the maximum T s , while ammonia ranged from 0.9 - 10 times. All observed behaviour was reproducible. Absolute humidity and storage temperature affected the sample integrity of acetone, ethanol and ammonia. Generally, the intra-bag variance was comparable between all storage temperatures and substrates while the inter-bag variation was affected by the absolute humidity. Only the initial and final concentrations between precursors for the 23℃ - 25℃ stored breath and nitrogen substrates agreed. The breath substrate samples gave erroneous values for ammonia. Permeation of compounds into the bags from the atmosphere was not significant. The overall issues surrounding storing breath in Tedlar™ bags for analysis using SIFTMS is not the loss of sample integrity, but the kinetics, precision and repeatability of the SIFT-MS instrument. The current kinetics are not adequate to accurately monitor acetone, isoprene, pentane, ammonia and ethanol in breath and stored in Tedlar™ bags at breath absolute humidity levels greater than 3%. Generally, the loss of sample integrity was only marginally outside the repeatability and precision of the machine.

When assessing preferences of individuals with developmental disabilities, choices can be described vocally or presented using objects or pictures in preference assessments. For individuals who are unable to perform auditory-visual discriminations and visual identity matching, objects instead of pictures or vocalizations need to be used for preference assessments to be effective. Considering the practical advantages of using pictures over objects, recent research has begun to focus on identifying and teaching skills needed for picture preference assessments. Although object-to-picture, picture-to-object, and generalized matching have been implicated as possible skills needed for picture preference assessments, further systematic studies are needed. The present study examined the relation between preference assessments (object vs. picture groups) and 5 discrimination skills. Based on direct paired-stimulus preference assessments completed at the beginning of the study, participants who could indicate their preferences with objects, but not with picture or vocal presentation, were assigned to the Object Group (n = 11); and participants who could indicate their preferences with both objects and pictures, but not vocal presentation, were assigned to the Picture Group (n = 9). The 5 discrimination tasks included: (a) object-picture matching and (b) its symmetry, picture-object matching; (c) generalized object-picture matching and (d) its symmetry, generalized picture-object matching; and (e) generalized identity picture-picture matching. All task stimuli were parts from everyday objects. Independent sample t-tests with Bonferroni correction showed that the percentages of correct responses were significantly higher in the Picture Group than in the Object Group on 4 of the 5 tasks (p < .01). Individual data showed that 8 of the 9 Picture Group participants met the pass criterion (80% or higher correct responses) on at least 1 discrimination task, with 6 participants passing 2 or more tasks. In contrast, only 1 of the 11 Object Group participants met the pass criterion on 1 discrimination task. The findings suggest that the effectiveness of picture preference assessments is not dependent on one specific discrimination, but possibly the ability to perform generalized matching.

This thesis explores the practical use of kernel smoothing in three areas: binary regression, density estimation and Poisson regression sample size calculations. Both nonparametric and semiparametric binary regression estimators are examined in detail, and extended to two bandwidth cases. The asymptotic behaviour of these estimators is presented in a unified way, and the practical performance is assessed using a simulation experiment. It is shown that, when using the ideal bandwidth, the two bandwidth estimators often lead to dramatically improved estimation. These benefits are not reproduced, however, when two general bandwidth selection procedures described briefly in the literature are applied to the estimators in question. Only in certain circumstances does the two bandwidth estimator prove superior to the one bandwidth semiparametric estimator, and a simple rule-of-thumb based on robust scale estimation is suggested. The second part summarises and compares many different approaches to improving upon the standard kernel method for density estimation. These estimators all have asymptotically 'better' behaviour than the standard estimator, but a small-sample simulation experiment is used to examine which, if any, can give important practical benefits. Very simple bandwidth selection rules which rely on robust estimates of scale are then constructed for the most promising estimators. It is shown that a particular multiplicative bias-correcting estimator is in many cases superior to the standard estimator, both asymptotically and in practice using a data-dependent bandwidth. The final part shows how the sample size or power for Poisson regression can be calculated, using knowledge about the distribution of covariates. This knowledge is encapsulated in the moment generating function, and it is demonstrated that, in most circumstances, the use of the empirical moment generating function and related functions is superior to kernel smoothed estimates.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on October 14, 2009. Major professor: David Clague, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Engineering, with specializations in Biomedical Engineering." "September 2009." Includes bibliographical references (p. 125-127).

JPEG and Excel data files for six siRNAs designed to silence Renilla luciferase transfected in Hela cells. For experimental details please see associated manuscript to be published in Cell Biology Education, 2006. A smaller data set and practice exercise are also included here.

abstract: The front end of almost all ADCs consists of a Sample and Hold Circuit in order to make sure a constant analog value is digitized at the end of ADC. The design of Track and Hold Circuit (THA) mainly focuses on following parameters: Input frequency, Sampling frequency, dynamic Range, hold pedestal, feed through error. This thesis will discuss the importance of these parameters of a THA to the ADCs and commonly used architectures of THA. A new architecture with SiGe HBT transistors in BiCMOS 130 nm technology is presented here. The proposed topology without complicated circuitry achieves high Spurious Free Dynamic Range(SFDR) and Total Harmonic Distortion (THD).These are important figure of merits for any THA which gives a measure of non-linearity of the circuit. The proposed topology is implemented in IBM8HP 130 nm BiCMOS process combines typical emitter follower switch in bipolar THAs and output steering technique proposed in the previous work. With these techniques and the cascode transistor in the input which is used to isolate the switch from the input during the hold mode, better results have been achieved. The THA is designed to work with maximum input frequency of 250 MHz at sampling frequency of 500 MHz with input currents not more than 5mA achieving an SFDR of 78.49 dB. Simulation and results are presented, illustrating the advantages and trade-offs of the proposed topology. / Dissertation/Thesis / M.S. Electrical Engineering 2012