Analysis and Optimization for Volume Holographic Recrording

Methods for analysis and optimization of volume holographic recording are presented for two main groups of applications. In the first group of applications (mainly storage systems), the designs and the techniques of volume holography are well known and the main optimization effort is finding the proper material to store the holograms. One of the results of this research is complete global optimization of dynamic range and sensitivity in two-center recording that is the best technique for persistent rewritable storage. For this purpose, a complete theoretical analysis as well as experimental demonstration is presented. Also, other effects and processes such as electron tunneling and recording at high temperature are considered for possible improvement of the dynamic range of the material. For the second group of applications (mainly holographic optical elements), the focus of this research is on analysis and optimization of the design of the volume holograms in contrast to material optimization. A new method (multi-grating method) is developed for the analysis of an arbitrary hologram that is based on the representation of the hologram as the superposition of several plane wave gratings. Based on this method, a new class of optical devices that integrates the functionalities of different optical elements into a simple volume hologram is introduced and analyzed. As a result, very compact, low cost, and easy to use devices such as portable spectrometers can be made with particular applications in biological and environmental sensing.Ph.D.Committee Chair: Adibi, Ali; Committee Member: Buck, John; Committee Member: Gaylord, Thomas; Committee Member: Smith, Glenn; Committee Member: Trebino, Ric

Human factors considerations in designing for infection prevention and control in neonatal care – findings from a pre-design inquiry

Qualitative data collection methods drawn from the early stages of human-centred design frameworks combined with thematic analysis were used to develop an understanding of infection prevention practice within an existing neonatal intensive care unit. Findings were used to generate a framework of understanding which in turn helped inform a baseline approach for future research and design development. The study revealed that a lack of clarity between infection transmission zones and a lack of design attributes needed to uphold infection prevention measures may be undermining healthcare workers’ understanding and application of good practice. The issue may be further complicated by well-intentioned behavioural attitudes to meeting work objectives; undue influences from spatial constraints; the influence of inadvertent and excessive touch-based interactions; physical and/or cognitive exertion to maintain transmission barriers; and the impact of expanding job design and increased workload to supplement for lack of effective barriers

Evaluation of critical thinking skills in ordinary and gifted secondary math curricula

Background and Objective:The art of arithmetic is as old as man, and critical thinking skills are always one of the tools that human beings use to face life's challenges. We face daily decisions that require reasoning, comprehension, interpretation, analysis, and evaluation of information. Critical thinking skills enable a person to make credible and valuable decisions, to behave ethically, and to be able to adapt to environmental conditions. However, some math teachers seem to have difficulty in instilling the concept of critical thinking in their teaching methods, so students also perform below average performance in math tests due to difficulty in understanding this concept. Therefore, students lack the necessary ability to formulate hypotheses and evaluate them using abstract ideas. Despite the emphasis on the development of critical thinking, numerous studies indicate that schools do not yet have critical thinking on their agenda. On the other hand, the international study of mathematics and science education trends (TIMSS), which is one of the most important and largest comparative studies in the field of academic achievement evaluation, reveals the fact of the weakness of Iranian students in mathematics. However, despite the high investment in the mathematics sector, the gap between Iranian students' mathematical knowledge and other countries is worrying. The purpose of the present study was to evaluate the status of critical thinking skills in mathematics curriculum in ordinary and gifted schools. Methods: The sample consisted of 71 math teachers, 360 students, three math textbooks and three supplementary math books of junior high school in the city of Shiraz, along with TIMSS mathematics questions. California critical thinking skills test (CCTST) was used to evaluate the critical thinking skills of students and teachers of mathematics. Math textbooks, math supplementary books, and TIMSS mathematical questions were analyzed using quantitative content analysis. The gathered data were analyzed through t-test for independent variable, one sample t-test, and chi square test. Findings: The following were found: Critical thinking skills are significant contributors in TIMSS. Also, the results of content analysis showed that in textbooks and supplementary math books, analysis component was the highest portion and inductive reasoning and evaluation had a minimal contribution. On the other hand, there was no significant difference between ordinary and gifted students in math exam. There was significant difference between ordinary and gifted students only in analysis skills. There was no significant difference between ordinary and gifted teachers in critical thinking. Conclusion:The weakness of Iranian students in the Thames test is a significant consequence of the weakness of math teachers in critical thinking skills and also the small share of math textbooks in the components of critical thinking skills. Therefore, it is suggested that the module of the five critical thinking skills course be designed while serving educators and implemented for math teacher

An integrative computational model for intestinal tissue renewal

Objectives\ud \ud The luminal surface of the gut is lined with a monolayer of epithelial cells that acts as a nutrient absorptive engine and protective barrier. To maintain its integrity and functionality, the epithelium is renewed every few days. Theoretical models are powerful tools that can be used to test hypotheses concerning the regulation of this renewal process, to investigate how its dysfunction can lead to loss of homeostasis and neoplasia, and to identify potential therapeutic interventions. Here we propose a new multiscale model for crypt dynamics that links phenomena occurring at the subcellular, cellular and tissue levels of organisation.\ud \ud Methods\ud \ud At the subcellular level, deterministic models characterise molecular networks, such as cell-cycle control and Wnt signalling. The output of these models determines the behaviour of each epithelial cell in response to intra-, inter- and extracellular cues. The modular nature of the model enables us to easily modify individual assumptions and analyse their effects on the system as a whole.\ud \ud Results\ud \ud We perform virtual microdissection and labelling-index experiments, evaluate the impact of various model extensions, obtain new insight into clonal expansion in the crypt, and compare our predictions with recent mitochondrial DNA mutation data. \ud \ud Conclusions\ud \ud We demonstrate that relaxing the assumption that stem-cell positions are fixed enables clonal expansion and niche succession to occur. We also predict that the presence of extracellular factors near the base of the crypt alone suffices to explain the observed spatial variation in nuclear beta-catenin levels along the crypt axis

The Recognizability and Localizability of Auditory Alarms: Setting Global Medical Device Standards.

Objective Four sets of eight audible alarms matching the functions specified in IEC 60601-1-8 were designed using known principles from auditory cognition with the intention that they would be more recognizable and localizable than those currently specified in the standard. Background The audible alarms associated with IEC 60601-1-8, a global medical device standard, are known to be difficult to learn and retain, and there have been many calls to update them. There are known principles of design and cognition that might form the basis of more readily recognizable alarms. There is also scope for improvement in the localizability of the existing alarms. Method Four alternative sets of alarms matched to the functions specified in IEC 60601-1-8 were tested for recognizability and localizability and compared with the alarms currently specified in the standard. Results With a single exception, all prototype sets of alarms outperformed the current IEC set on both recognizability and localizability. Within the prototype sets, auditory icons were the most easily recognized, but the other sets, using word rhythms and simple acoustic metaphors, were also more easily recognized than the current alarms. With the exception of one set, all prototype sets were also easier to localize. Conclusion Known auditory cognition and perception principles were successfully applied to an existing audible alarm problem. Application This work constitutes the first (benchmarking) phase of replacing the alarms currently specified in the standard. The design principles used for each set demonstrate the relative ease with which different alarm types can be recognized and localized

Validation of digital pathology imaging for primary histopathological diagnosis

Aims: Digital pathology (DP) offers advantages over glass slide microscopy (GS), but data demonstrating a statistically valid equivalent (i.e. non-inferior) performance of DP against GS are required to permit its use in diagnosis. The aim of this study is to provide evidence of non-inferiority. Methods and results: Seventeen pathologists re-reported 3017 cases by DP. Of these, 1009 were re-reported by the same pathologist, and 2008 by a different pathologist. Re-examination of 10 138 scanned slides (2.22 terabytes) produced 72 variances between GS and DP reports, including 21 clinically significant variances. Ground truth lay with GS in 12 cases and with DP in nine cases. These results are within the 95% confidence interval for existing intraobserver and interobserver variability, proving that DP is non-inferior to GS. In three cases, the digital platform was deemed to be responsible for the variance, including a gastric biopsy, where Helicobacter pylori only became visible on slides scanned at the ×60 setting, and a bronchial biopsy and penile biopsy, where dysplasia was reported on DP but was not present on GS. Conclusions: This is one of the largest studies proving that DP is equivalent to GS for the diagnosis of histopathology specimens. Error rates are similar in both platforms, although some problems e.g. detection of bacteria, are predictable

Designing informative warning signals: Effects of indicator type, modality, and task demand on recognition speed and accuracy

An experiment investigated the assumption that natural indicators which exploit existing learned associations between a signal and an event make more effective warnings than previously unlearned symbolic indicators. Signal modality (visual, auditory) and task demand (low, high) were also manipulated. Warning effectiveness was indexed by accuracy and reaction time (RT) recorded during training and dual task test phases. Thirty-six participants were trained to recognize 4 natural and 4 symbolic indicators, either visual or auditory, paired with critical incidents from an aviation context. As hypothesized, accuracy was greater and RT was faster in response to natural indicators during the training phase. This pattern of responding was upheld in test phase conditions with respect to accuracy but observed in RT only in test phase conditions involving high demand and the auditory modality. Using the experiment as a specific example, we argue for the importance of considering the cognitive contribution of the user (viz., prior learned associations) in the warning design process. Drawing on semiotics and cognitive psychology, we highlight the indexical nature of so-called auditory icons or natural indicators and argue that the cogniser is an indispensable element in the tripartite nature of signification