Electroretinagram (ERG) is the recording of electrical activity of retinal cells elicited by light stimulation, which has been widely used to help diagnose different types of retinal dysfunctions. The ERG response signal is a short non-stationary signal that contains overlapping components. Different Digital Signal Processing (DSP) techniques are investigated using MATLAB to study the time-frequency responses of the ERG signal such as Short Time Fourier Transform (STFT), Continuous Wavelet Transform (CWT) and Discrete Wavelet Transform (DWT). The Photopic ERG signal was processed and analyzed in this thesis and the results of each technique have been investigated in detail. The Photopic ERG components have been extracted using DWT and ERG Models.

Master of Science / Department of Architectural Engineering and Construction Science / Raphael A. Yunk / Sustainable design and green engineering practices have become a priority in the architectural design industry over the past few years. Energy codes and standards have become more stringent as energy costs rise and buildings become larger, consuming more energy and having a larger impact on the environment. One major area for improvement to meet these new requirements is in the lighting area. Kansas State University (KSU) in Manhattan, KS has had the same campus walkway lighting system for over 50 years and it does not meet the current energy codes and standards. This paper will perform a case study of the current walkway lighting system on the KSU campus, specifically focusing on the Quad area and applying the same principles to the entire campus. The illumination and fixture distribution characteristics will first be established and analyzed to determine an accurate baseline for later comparison. Issues regarding the illumination, efficiency, aesthetics, maintenance, and landscaping will be addressed once the current conditions are established. Lighting technology has changed dramatically in the past year with the development of high efficiency fluorescent, induction, and light emitting diode (LED) lighting. New LED technology has proven to be the most efficient and has been adapted to create outdoor LED fixtures that could help KSU surpass the current energy standards and improve the overall quality of light to correct some of the current issues the existing lighting creates. A full analysis of the illumination, efficiency, aesthetics, and economic feasibility will be performed. The economic analysis will compare existing maintenance and energy costs to that of the first-cost with maintenance, and energy costs to determine an estimated payback. Once the analysis is complete, future options for KSU to implement new lighting technology will be discussed. By creating a more environmentally conscious campus, using high efficiency lighting, KSU could set an example for other universities to pursue sustainable technology and design.

Studies demonstrate short-wavelength cone pathway dysfunction in patients with diabetes and no clinically visible DR. Poor glycemic control, as measured by hemoglobin A1c (HbA1c), is a strong risk factor for DR. We hypothesized that raised HbA1c was associated with short-wavelength cone sensitive visual evoked potential (S-VEP) and electroretinogram (sERG) dysfunction. Forty adolescents with diabetes and 39 controls were tested using the S-VEP. Latencies to a short-wavelength stimulus were delayed in patients at low contrasts. Patient S-VEP latencies were not associated with HbA1c when controlling for age and time since diagnosis. Twenty-one adolescents with diabetes and 19 controls were tested using the sERG. Implicit times of the b-wave were delayed but not associated with HbA1c when controlling for time since diagnosis.Patient PhNR amplitudes were reduced. A one-unit increase in HbA1c was associated with a 15% sERG PhNR amplitude reduction (p=0.004). The sERG PhNR may be a potential biomarker for DR.

Studies demonstrate short-wavelength cone pathway dysfunction in patients with diabetes and no clinically visible DR. Poor glycemic control, as measured by hemoglobin A1c (HbA1c), is a strong risk factor for DR. We hypothesized that raised HbA1c was associated with short-wavelength cone sensitive visual evoked potential (S-VEP) and electroretinogram (sERG) dysfunction. Forty adolescents with diabetes and 39 controls were tested using the S-VEP. Latencies to a short-wavelength stimulus were delayed in patients at low contrasts. Patient S-VEP latencies were not associated with HbA1c when controlling for age and time since diagnosis. Twenty-one adolescents with diabetes and 19 controls were tested using the sERG. Implicit times of the b-wave were delayed but not associated with HbA1c when controlling for time since diagnosis.Patient PhNR amplitudes were reduced. A one-unit increase in HbA1c was associated with a 15% sERG PhNR amplitude reduction (p=0.004). The sERG PhNR may be a potential biomarker for DR.

After over a decade of its discovery, the Electroretinogram (ERG) still remains the objective tool that is conventionally used in assessment of retinal function in health and disease. Although there is ongoing research in developing ERG- recording techniques, interpretation and clinical applications, there is still a limited understanding on how each photoreceptor class contribute to the ERG waveform and their role and/or susceptibilities in various retinal diseases still remains unclear. Another limitation with currently used conventional testing protocols in a clinical setting is the requirement of an adaptation period which is time-consuming. Furthermore, the ERG responses derived in this manner are recorded under different stimulus conditions, thus, making comparison of these signals difficult. To address these issues and develop a new testing method, we employed silent substitution paradigm in obtaining cone- and rod- isolating ERGs using sine- and square- wave temporal profiles. The ERGs achieved in this manner were shown to be photoreceptor-selective. Furthermore, these responses did not only provide the functional index of photoreceptors but their contributions to their successive postreceptoral pathways. We believe that the substitution stimuli used in this thesis could be a valuable tool in functional assessment of individual photoreceptor classes in normal and pathological conditions. Furthermore, we speculate that this method of cone/rod activity isolation could possibly be used in developing faster and efficient photoreceptor-selective testing protocols without the need of adaptation. / Bradford School of Optometry and Vision Sciences

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-09-23T14:07:17Z No. of bitstreams: 1 cristianogomescasagrande.pdf: 22950240 bytes, checksum: 13f9d8db507365054c57ae6d1bfd91ae (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-09-26T20:30:58Z (GMT) No. of bitstreams: 1 cristianogomescasagrande.pdf: 22950240 bytes, checksum: 13f9d8db507365054c57ae6d1bfd91ae (MD5) / Made available in DSpace on 2016-09-26T20:30:58Z (GMT). No. of bitstreams: 1 cristianogomescasagrande.pdf: 22950240 bytes, checksum: 13f9d8db507365054c57ae6d1bfd91ae (MD5) Previous issue date: 2016-04-14 / Os sistemas de iluminação pública (IP) no Brasil atravessam um momento de mudanças significativas, que implicam em novos paradigmas, desafios e perspectivas para o setor. Essas transformações começam com a transferência dos ativos de IP para os municípios, exigindo que os gestores municipais estejam preparados e capacitados para assumir esse serviço público essencial que anteriormente não era de sua responsabilidade. Além disso, novas tecnologias de iluminação, como os diodos emissores de luz (LEDs), surgem como alternativa às tecnologias convencionais, acarretando muitos impactos e alterações de conceitos no projeto, gestão e manutenção dos sistemas de IP. Assim, esta tese traça um panorama da iluminação pública no país, abrangendo questões referentes à gestão e manutenção do sistema, enfatizando os desafios ligados à transferência dos ativos de iluminação pública para os municípios, além da complexidade inerente à mudança de tecnologia para os LEDs. A discussão é organizada em duas vertentes principais: a gestão da IP, com ênfase nos desafios associados à transferência dos ativos; e a consolidação de novas tecnologias, sobretudo os LEDs. Nesse âmbito, com o objetivo de contribuir para uma utilização mais eficiente dos sistemas de iluminação, este trabalho propõe a consolidação da fotometria mesópica na elaboração de projetos luminotécnicos de IP, uma vez que, nesses casos, é comum deparar-se com condições de baixa luminância, nas quais a sensibilidade espectral da visão humana é diferente das condições supostas pela fotometria clássica. Neste sentido, procura-se explorar em detalhes a recomendação CIE 191:2010, que propõe multiplicadores de correção para a adaptação de grandezas fotométricas convencionais em grandezas mesópicas. Todavia, para se obter tais multiplicadores, é necessária a obtenção da relação entre os fluxos escotópico e fotópico da fonte luminosa (relação S/P), o que exige equipamentos especiais não facilmente disponíveis à maior parte dos projetistas. Com o objetivo de contornar essa dificuldade, esta tese de doutorado propõe uma equação geral que permita realizar o cálculo de S/P em função da temperatura de cor correlata e do índice de reprodução de cor da fonte de luz a ser empregada, que são informações normalmente disponibilizadas nos catálogos de fabricantes ou embalagens de lâmpadas comerciais. A equação encontrada apresentou coeficientes de correlação e de determinação próximos da unidade, o que lhe garante boa confiabilidade. Pela obtenção da relação S/P com auxílio da técnica proposta, um projeto luminotécnico típico tem sua rotina alterada, algo que é demonstrado e exemplificado ao final do texto. / The street lighting systems in Brazil are going through a time of significant changes that involve new paradigms, challenges and prospects for the sector. These changes begin with the transfer of street lighting assets to municipalities, demanding that municipal managers are prepared and able to manage this essential public service that previously was not your responsibility. In addition, new lighting technologies such as light-emitting diodes (LED) are an alternative to conventional technologies, resulting in many impacts and changes of concepts in the design, management and maintenance of street lighting systems. Thus, this thesis provides an overview of street lighting in Brazil, covering issues relating to the management and maintenance of the system, emphasizing the challenges linked to the transfer of street lighting assets to the municipalities, in addition to the inherent complexity of LED technology. The discussion is organized into two main areas: the management of system, with emphasis on the challenges associated with the transfer of assets; and the consolidation of new technologies, especially the LED. In this context, in order to contribute to a more efficient use of lighting systems, this thesis proposes the consolidation of mesopic photometry in the development of street lighting projects, since in such cases it is common to encounter poor conditions luminance, in which the spectral sensitivity of human vision is different from the conditions in the classical photometry. In this sense, it is covered in detail the CIE 191:2010 technical report, which proposes correction factors for the adaptation of conventional photometric quantities in mesopic quantities. However, to obtain such factors, it is required to obtain the relationship between the scotopic and photopic luminous flux of light source (S/P ratio), which requires special equipment not readily available to most lighting designers. Thus, this PhD thesis proposes a general equation that provides the S/P ratio as a mathematical function of correlated color temperature and color rendering index of the light source, which are information usually available in catalogs of manufacturers or products packaging. The proposed equation showed correlation coefficient and coefficient of determination parameters closed to unity, which guarantees good reliability. By obtaining the S/P ratio with the aid of proposed technique, a typical lighting design has changed his routine, something that is demonstrated and exemplified in final of the text.