Endoscopic optical coherence tomography : design and application

This thesis presents an investigation on endoscopic optical coherence tomography (OCT). As a noninvasive imaging modality, OCT emerges as an increasingly important diagnostic tool for many clinical applications. Despite of many of its merits, such as high resolution and depth resolvability, a major limitation is the relatively shallow penetration depth in tissue (about 2∼3 mm). This is mainly due to tissue scattering and absorption. To overcome this limitation, people have been developing many different endoscopic OCT systems. By utilizing a minimally invasive endoscope, the OCT probing beam can be brought to the close vicinity of the tissue of interest and bypass the scattering of intervening tissues so that it can collect the reflected light signal from desired depth and provide a clear image representing the physiological structure of the region, which can not be disclosed by traditional OCT. In this thesis, three endoscope designs have been studied. While they rely on vastly different principles, they all converge to solve this long-standing problem.

A hand-held endoscope with manual scanning is first explored. When a user is holding a hand- held endoscope to examine samples, the movement of the device provides a natural scanning. We proposed and implemented an optical tracking system to estimate and record the trajectory of the device. By registering the OCT axial scan with the spatial information obtained from the tracking system, one can use this system to simply ‘paint’ a desired volume and get any arbitrary scanning pattern by manually waving the endoscope over the region of interest. The accuracy of the tracking system was measured to be about 10 microns, which is comparable to the lateral resolution of most OCT system. Targeted phantom sample and biological samples were manually scanned and the reconstructed images verified the method.

Next, we investigated a mechanical way to steer the beam in an OCT endoscope, which is termed as Paired-angle-rotation scanning (PARS). This concept was proposed by my colleague and we further developed this technology by enhancing the longevity of the device, reducing the diameter of the probe, and shrinking down the form factor of the hand-piece. Several families of probes have been designed and fabricated with various optical performances. They have been applied to different applications, including the collector channel examination for glaucoma stent implantation, and vitreous remnant detection during live animal vitrectomy.

Lastly a novel non-moving scanning method has been devised. This approach is based on the EO effect of a KTN crystal. With Ohmic contact of the electrodes, the KTN crystal can exhibit a special mode of EO effect, termed as space-charge-controlled electro-optic effect, where the carrier electron will be injected into the material via the Ohmic contact. By applying a high voltage across the material, a linear phase profile can be built under this mode, which in turn deflects the light beam passing through. We constructed a relay telescope to adapt the KTN deflector into a bench top OCT scanning system. One of major technical challenges for this system is the strong chromatic dispersion of KTN crystal within the wavelength band of OCT system. We investigated its impact on the acquired OCT images and proposed a new approach to estimate and compensate the actual dispersion. Comparing with traditional methods, the new method is more computational efficient and accurate. Some biological samples were scanned by this KTN based system. The acquired images justified the feasibility of the usage of this system into a endoscopy setting. My research above all aims to provide solutions to implement an OCT endoscope. As technology evolves from manual, to mechanical, and to electrical approaches, different solutions are presented. Since all have their own advantages and disadvantages, one has to determine the actual requirements and select the best fit for a specific application.

Achieving Coherence between Strategies and Value Systems in Collaborative Networks

Part 8: Business Strategies Alignment

An ESL/EFL Computer Assisted Language Instruction (CALIS) Micro-Teaching Lesson on Coherence Through Sentences When Writing Compositions in the Foreign Language Classroom

[Sin resumen]

Quality of life, sense of coherence and levels of sedentarism of faculty and staff from the Presbítero Benjamín Núnez, U.N.A.

The aim of this study was to analyze the quality of life of faculty and staff of the Presbítero Benjamín Núñez Campus of Universidad Nacional (UNA, Costa Rica) as well as to assess the influence of two factors, sense of coherence and physical exercise, in the quality of life of the subjects.  A group of 37 faculty members and 30 staff members participated in the study.  The SF-36 Questionnaire, the Sense of Coherence Scale, and a survey to measure physical exercise habits were used.  In general, results showed a relatively good quality of life and similar scores were found in the Sense of Coherence Scale.  Additionally, significant connections were found between certain factors related to sense of coherence and quality of life.  Data confirmed that persons who practice physical exercise have a better quality of life than those who are not physically active.  It was concluded that, although quality of life and sense of coherence were relatively good, new proposals must be designed and implemented to improve both aspects.  In this sense, physical exercise proved to be one of the pillars in the development of innovative proposals aimed at bettering health in university employees, all of this within the “Healthy Universities” concept.

Security framework and protocols for the internet of things

This study was conducted to protect security of human beings and businesses from intruders in the context of IoT which is next generation internet. We have developed a universal framework and a number of communication protocols to provide security that will make IoT cyber world safer for all t users.

Staff compliance with protocols to improve the management of behavioral and psychological symptoms of dementia

Using data from a larger study investigating the effectiveness of a structured clinical protocol to manage individuals in residential facilities who experience behavioral and psychological symptoms of dementia (BPSD), the current study investigated whether external clinical support in using the protocol with specific residents increased compliance in its use, over and above only providing a generic workshop about the protocol and management of BPSD. Results indicated that provision of the workshop, in addition to clinical support, was associated with significantly higher compliance. However, compliance was only found to be related to positive outcomes when staff received the generic workshop and not clinical support. When clinical support was provided, compliance was not related to outcomes or worse outcomes. These findings, when considered in the context of the results of the larger trial, suggest that the relationship among clinical support, compliance with BPSD protocols, and clinical outcomes for residents and staff is complex and needs further investigation.

Energy-efficiency analysis of cluster-based routing protocols in wireless sensor network

This paper extends the conditions of the cluster-based routing protocols in terms of general algorithm complexity of data fusion, general compressing ratio of data fusion, and network area with long distance. Corresponding three general evaluation methods to evaluate the energy efficiency of the cluster-based routing protocols such as LEACH, PEGASIS, and BCDCP are provided. Moreover, three facts are found in them: (1) High-level software energy macro model is used to compute the energy dissipation of general data fusion software and make the constant value of energy dissipation of 1-bit data fusion an especial instance. (2) Multi-hop energy efficiency is related to the radio hardware parameters and the dynamic topology of network and the above protocols do not exploit the best use of the energy efficiency of multi-hop scheme. (3) High-energy dissipation non-cluster-head nodes, whose number changes with the density of the sensor nodes in clusters, worsen the death of nodes. The numerical results of experiments reprove these discoveries. Furthermore, they provide helpful guide for improving the above routing protocols to extent their application ranges.

Australian prosecutors perceptions of the utility of child investigative interview protocols

Investigative interviews with alleged victims form the central plank of evidence in the prosecution of child sexual abuse. Despite interviewers being provided with a guiding framework, child sexual abuse cases are often not prosecuted because of poor-quality evidence. The purpose of this study was to elicit feedback from prosecutors about the structure and format of current interview protocols and the ways in which these could potentially be improved from an evidential perspective. Focus group discussions (ranging in length from 180 to 190 minutes) were conducted with 13 Crown prosecutors representing every jurisdiction of Australia. Thematic analysis of the focus group discussions revealed that prosecutors were supportive of the structure of interview protocols, however, concerns were raised about four of the interview elements. These elements were the oath and truth–lie competency test, the ground rules, the practice narrative and eliciting a disclosure. The prosecutors’ concerns and their implications for protocol developers and trainers are discussed.

Planning for country: empowering built environment students with Indigenous protocols and knowledge

Increasingly, Built Environment (BE) professionals, including planner, architect and landscape architect practitioners, are becoming involved in the planning and design of projects for, and in direct consultation with Indigenous communities and their proponents. These projects range from inserting Indigenous cultural landscape analysis into planning schemes, including Indigenous protocols and aspirations in policy statements; designing cultural centres, information centres and housing; drafting cultural tourism strategies and devising cross-cultural land management plans. This entails working with Indigenous communities or their nominated representatives as stakeholders in community engagement, consultation, and planning processes. Critically, BE professionals must be able to plan and design with regard to Indigenous community’s cultural protocols, issues and values. Yet many (domestic and or international) students graduate with little or no comprehension of Indigenous knowledge systems or the protocols for engagement with the communities in which they are required to work, whether they be Australian or international Indigenous communities. Contextually, both PIA and the planning academe have struggled with coming to terms with this realm over the last 10 years. This paper will report on a recently completed Australian Government Office of Learning & Teaching (OLT) funded research project that has sought to improve opportunities to improve the knowledge and skills of tertiary students in the BE professions through the enhancement of their competency, appreciation and respect for Indigenous protocols and processes that also implicates the professional accreditation systems that these courses are accountable. It has proposed strategies and processes to expose students in the BE professions to Australian Indigenous knowledge and cultural systems and the protocols for engaging with Indigenous Australians about their rights, interests, needs and aspirations. Included in these findings is the provision of a tool that enables and offers guidance to BE tertiary students and academics how to enhance comprehension, exposure to, and knowledge and cultural systems of, Indigenous Australians. While the scope of this report is cross-BE, this paper will focus upon the planning practice, policy and academe realms.

Effect of pharmacological pupil dilation on measurements and iol power calculation made using the new swept-source optical coherence tomography-based optical biometer

Purpose: to determine whether pupil dilation affects biometric measurements and intraocular lens (IOL) power calculation made using the new swept-source optical coherence tomography-based optical biometer (IOLMaster 700©; Carl Zeiss Meditec, Jena, Germany). Procedures: eighty-one eyes of 81 patients evaluated for cataract surgery were prospectively examined using the IOLMaster 700© before and after pupil dilation with tropicamide 1%. The measurements made were: axial length (AL), central corneal thickness (CCT), aqueous chamber depth (ACD), lens thickness (LT), mean keratometry (MK), white-to-white distance (WTW) and pupil diameter (PD). Holladay II and SRK/T formulas were used to calculate IOL power. Agreement between measurement modes (with and without dilation) was assessed through intraclass correlation coefficients (ICC) and Bland-Altman plots. Results: mean patient age was 75.17 ± 7.54 years (range: 57–92). Of the variables determined, CCT, ACD, LT and WTW varied significantly according to pupil dilation. Excellent intraobserver correlation was observed between measurements made before and after pupil dilation. Mean IOL power calculation using the Holladay 2 and SRK/T formulas were unmodified by pupil dilation. Conclusions: the use of pupil dilation produces statistical yet not clinically significant differences in some IOLMaster 700© measurements. However, it does not affect mean IOL power calculation.

Agreement and clinical comparison between a new swept-source optical coherence tomography-based optical biometer and an optical low-coherence reflectometry biometer

Purpose To compare measurements taken using a swept-source optical coherence tomography-based optical biometer (IOLmaster 700) and an optical low-coherence reflectometry biometer (Lenstar 900), and to determine the clinical impacts of differences in their measurements on intraocular lens (IOL) power predictions. Methods Eighty eyes of 80 patients scheduled to undergo cataract surgery were examined with both biometers. The measurements made using each device were axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), lens thickness (LT), mean keratometry (MK), white-to-white distance (WTW), and pupil diameter (PD). Holladay 2 and SRK/T formulas were used to calculate IOL power. Differences in measurement between the two biometers were determined using the paired t-test. Agreement was assessed through intraclass correlation coefficients (ICC) and Bland–Altman plots. Results Mean patient age was 76.3±6.8 years (range 59–89). Using the Lenstar, AL and PD could not be measured in 12.5 and 5.25% of eyes, respectively, while IOLMaster 700 took all measurements in all eyes. The variables CCT, AQD, LT, and MK varied significantly between the two biometers. According to ICCs, correlation between measurements made with both devices was excellent except for WTW and PD. Using the SRK/T formula, IOL power prediction based on the data from the two devices were statistically different, but differences were not clinically significant. Conclusions No clinically relevant differences were detected between the biometers in terms of their measurements and IOL power predictions. Using the IOLMaster 700, it was easier to obtain biometric measurements in eyes with less transparent ocular media or longer AL.