Dampening Spontaneous Activity Improves the Light Sensitivity and Spatial Acuity of Optogenetic Retinal Prosthetic Responses

Retinitis pigmentosa is a progressive retinal dystrophy that causes irreversible visual impairment and blindness. Retinal prostheses currently represent the only clinically available vision-restoring treatment, but the quality of vision returned remains poor. Recently, it has been suggested that the pathological spontaneous hyperactivity present in dystrophic retinas may contribute to the poor quality of vision returned by retinal prosthetics by reducing the signal-to-noise ratio of prosthetic responses. Here, we investigated to what extent blocking this hyperactivity can improve optogenetic retinal prosthetic responses. We recorded activity from channelrhodopsin-expressing retinal ganglion cells in retinal wholemounts in a mouse model of retinitis pigmentosa. Sophisticated stimuli, inspired by those used in clinical visual assessment, were used to assess light sensitivity, contrast sensitivity and spatial acuity of optogenetic responses; in all cases these were improved after blocking spontaneous hyperactivity using meclofenamic acid, a gap junction blocker. Our results suggest that this approach significantly improves the quality of vision returned by retinal prosthetics, paving the way to novel clinical applications. Moreover, the improvements in sensitivity achieved by blocking spontaneous hyperactivity may extend the dynamic range of optogenetic retinal prostheses, allowing them to be used at lower light intensities such as those encountered in everyday life

The Immigrant Earnings Disadvantage across the Earnings and Skills Distributions: The Case of Immigrants from the EU’s New Member States in Ireland

As the movement of population from the New Member States (NMS) of the EU to the older members is a relatively new flow, it is important to build up our knowledge of who is moving within Europe and how they are performing in their destinations. In this paper, we analyse the earnings of immigrants in Ireland from the NMS using a new large-scale dataset on employees in Ireland. In so doing, we add to the emerging strand in the literature on immigrant earnings that looks beyond average earnings differentials and considers variations in such differentials across the earnings and skills distributions. We do this partly by using quantile regressions and also by analyzing earnings differentials within educational categories. We find that the average earnings difference between immigrants from the NMS and natives is between 10 percent and 18 percent, depending on the controls used. However, the difference is found to be either non-existent or low for people with low skill levels and for people at the lower end of the earnings distribution. The difference is higher for those at the upper ends of the skills and earnings distributions. This suggests that the transferability of human capital is a crucial determinant of the immigrant-native earnings gap for NMS immigrants in Ireland.new member states, Ireland, immigrant earnings, quantile regression

A note on area variables in Regge calculus

We consider the possibility of setting up a new version of Regge calculus in four dimensions with areas of triangles as the basic variables rather than the edge-lengths. The difficulties and restrictions of this approach are discussed.Comment: 4 pages, amstex. Revision has minor changes and more precise conclusion

InterVarsity Christian Fellowship

Student perspectives on worship services from Instructor Jennifer Garvin-Sanchez\u27s Religious Studies 108 Human Spirituality course at Virginia Commonwealth University

Grace and Holy Trinity Episcopal Church

Student perspectives on worship services from Instructor Jennifer Garvin-Sanchez\u27s Religious Studies 108 Human Spirituality course at Virginia Commonwealth University

Studies in the chemistry of ergosterol

Imperial Users onl

Using Virtual Reality Modelling to Enhance Electrical Safety and Design in the Built Environment.

This thesis presents a prototype desktop virtual reality model entitled ‘Virtual Electrical Services’, to enhance electrical safety and design in the built environment. The model presented has the potential to be used as an educational tool for third level students, a design tool for industry, or as a virtual electrical safety manual for the general public. A description of the development of the virtual reality model is presented along with the applications that were developed within the model. As part of the VR development process, this research investigates the cause and effects of electrical accidents in domestic properties. This highlights the high-risk activities, which lead to receiving an electric shock in a domestic property and identifies at-risk groups that could most benefit from electrical safety interventions. It also examines the theory of transfer touch voltage calculations and expands on it to show how to carry out a sensitivity analysis in relation to the design parameters that are being used by designers and installers. The use of Desktop Virtual Reality systems for enhancing electrical safety and engineering design is a novel prospect for both practicing and student electrical services engineers. This innovative approach, which can be readily accessed via the World Wide Web, constitutes a marked shift in conventional learning and design techniques to a more immersive, interactive and intuitive working and learning environment. A case study is carried out to evaluate the users’ attitudes toward VR learning environments and also the usability of the prototype model developed. From the completed case study, it appears that there is sufficient evidence to suggest that virtual reality could enhance electrical safety and design in the built environment and also advance training methods used to educate electrical services engineers and electricians. The thesis includes a discussion on the limitations of the system developed and the potential for future research and developmen

Information transmission in normal vision and optogenetically resensitised dystrophic retinas

Phd ThesisThe retina is a sophisticated image processing machine, transforming the visual scene as detected by the photoreceptors into a pattern of action potentials that is sent to the brain by the retinal ganglion cells (RGCs), where it is further processed to help us understand and navigate the world. Understanding this encoding process is important on a number of levels. First, it informs the study of upstream visual processing by elucidating the signals higher visual areas receive as input and how they relate to the outside world. Second, it is important for the development of treatments for retinal blindness, such as retinal prosthetics. In this thesis, I present work using multielectrode array (MEA) recordings of RGC populations from ex-vivo retinal wholemounts to study various aspects of retinal information processing. My results fall into two main themes. In the rst part, in collaboration with Dr Geo rey Portelli and Dr Pierre Kornprobst of INRIA, I use ashed gratings of varying spatial frequency and phase to compare di erent coding strategies that the retina might use. These results show that information is encoded synergistically by pairs of neurons and that, of the codes tested, a Rank Order Code based on the relative order of ring of the rst spikes of a population of neurons following a stimulus provides information about the stimulus faster and more e ciently than other codes. In the later parts, I use optogenetic stimulation of RGCs in congenitally blind retinas to study how visual information is corrupted by the spontaneous hyperactivity that arises as a result of photoreceptor degeneration. I show that by dampening this activity with the gap junction blocker meclofenamic acid, I can improve the signal-to-noise ratio, spatial acuity and contrast sensitivity of prosthetically evoked responses. Taken together, this work provides important insights for the future development of retinal prostheses

Illinois Vocational Student Service Network Equal Employment Opportunity/Affirmative Action Policy Development

The dual purposes of this field study were to ascertain the legislative, court, and administrative rule requirements for equal employment opportunity and affirmative action for the newly created Illinois Vocational Student Services Network and to develop equal employment opportunity and affirmative action policies for the network. The findings of this field study are applicable to Educational Service Regions in the State of Illinois and projects, entities, or programs that utilize Educational Service Regions as fiscal agents. With minor modifications, the affirmative action policy could be utilized by school districts and other public agencies. The study is divided into five major sections. The section entitled The Problem provides background material and states the problem and delineates the limitations of the study. The section entitled Review of Legislation, Administrative Rules and Court Cases reviews the sources as they impact equal employment opportunities and affirmative action policies. The section entitled Design of Study explains how the study was organized. The following section entitled Development of Necessary Policies and Procedures explains the necessity for each section, states the policy, and lists an implementation schedule. The final section, entitled Conclusion and Recommendations, draws upon the literature review to make specific recommendations

Immigrants and Employer-Provided Training

Much has been written about the labour market outcomes for immigrants in their host countries, particularly with regard to earnings, employment and occupational attainment. However, much less attention has been paid to the question of whether immigrants are as likely to receive employer-provided training relative to comparable natives. As such training should be crucial in determining the labour market success of immigrants in the long run it is a critically important question. Using data from a large scale survey of employees in Ireland, we find that immigrants are less likely to receive training from employers, with immigrants from the New Member States of the EU experiencing a particular disadvantage. The immigrant training disadvantage arises in part from a failure on the part of immigrants to get employed by training-oriented firms. However, they also experience a training disadvantage relative to natives within firms where less training is provided.immigrants, employer-provided training, Ireland