A high-order Nystrom discretization scheme for boundary integral equations defined on rotationally symmetric surfaces

A scheme for rapidly and accurately computing solutions to boundary integral equations (BIEs) on rotationally symmetric surfaces in R^3 is presented. The scheme uses the Fourier transform to reduce the original BIE defined on a surface to a sequence of BIEs defined on a generating curve for the surface. It can handle loads that are not necessarily rotationally symmetric. Nystrom discretization is used to discretize the BIEs on the generating curve. The quadrature is a high-order Gaussian rule that is modified near the diagonal to retain high-order accuracy for singular kernels. The reduction in dimensionality, along with the use of high-order accurate quadratures, leads to small linear systems that can be inverted directly via, e.g., Gaussian elimination. This makes the scheme particularly fast in environments involving multiple right hand sides. It is demonstrated that for BIEs associated with the Laplace and Helmholtz equations, the kernel in the reduced equations can be evaluated very rapidly by exploiting recursion relations for Legendre functions. Numerical examples illustrate the performance of the scheme; in particular, it is demonstrated that for a BIE associated with Laplace's equation on a surface discretized using 320,800 points, the set-up phase of the algorithm takes 1 minute on a standard laptop, and then solves can be executed in 0.5 seconds.Comment: arXiv admin note: substantial text overlap with arXiv:1012.56301002.200

Age effect on retina and optic disc normal values

Purpose: To investigate retinal thickness and optic disc parameters by the Retinal Thickness Analyzer (RTA) glaucoma program in older normal subjects and to determine any age effect. Methods: Subjects over 40 years of age without any prior history of eye diseases were recruited. Only subjects completely normal on clinical ophthalmologic examination and on visual field testing by Humphrey Field Analyzer (HFA) using the SITA 24-2 program were included. A total of 74 eyes from 74 subjects with even age distribution over the decades were enrolled and underwent topographic measurements of the posterior pole and of the optic disc by RTA. The `glaucoma full' program in software version 4.11B was applied. Results: Mean patient age was 59.9 +/- 10.3 years with a range from 40 to 80 years. The only parameter intraocular pressure (IOP) correlated with was retinal posterior pole asymmetry (r=0.27, p=0.02). IOP itself increased significantly with age (r=0.341, p=0.003). Mean defect and pattern standard deviation of the HFA did not correlate with any of the retinal or optic disc measurements. Increasing age correlated significantly with some of the morphologic measurements of the RTA: decreasing perifoveal minimum thickness (r=-0.258, p=0.026), increased cup-to-disc area ratio (r=0.302, p=0.016) and increased cup area (r=0.338 p=0.007). Conclusions: An age effect exists for some of the retina and optic disc measurements obtained by the RTA. Copyright (C) 2005 S. Karger AG, Basel

The evolution of drug discovery strategies

The modem pharmaceutical organisation is driven by the need to discover, develop and market innovative pharmaceutical products. Key to this mission is the process of drug discovery that involves allocating vast resources to (i) identify appropriate target diseases, (ii) discover and confirm appropriate solutions, (iii) clinically develop and legally approve the solution, for (iv) manufacture and supply of the product. Historically the drug discovery process was led by curiosity and pure research, but today it is akin to a factory system that conducts mass volume, applied and market focused research This change in focus has also been companied by numerous advancements in science, technology and market expectations As will be shown and verified in this thesis, there is relatively little in the way of existing literature and studies that focus on drug discovery strategies, and what does exist is fragmented across a number of disciplines including technology management, chemistry, automation, marketing, knowledge management and strategy. With this background, the aim of this thesis is to make a contribution that includes understanding and defining the concept of drug discovery as a strategy, and exploring how such strategies change through time. Within management and organisational literature, there is a body of knowledge that seeks to understand how and why organisations develop different strategies and organisational forms. This thesis adopts this evolutionary and classification paradigm to examine, define and classify the different strategies that exist to discover drugs In particular, four requirements of evolution (existence in populations, the process of variation, the process of heredity, and the process of selection) are identified and translated into a strategic management and drug discovery context to create four testable hypotheses. These are: 1. There are similar drug discovery strategies employed by different organisations to form populations whose (the population’s) size follows a concave pattern of growth and decline. 2. Within a drug discovery population, there are strategies that differ to each other in terms of their characteristics and their fitness. 3. Those characteristics of drug discovery strategies credited with successful drug discovery performance are likely to appear in future strategic configurations, while those characteristics that are not, are likely to be absent. 4 With a change in the environmental conditions those drug discovery strategies that remain, are the ones whose strategic characteristics are favoured by the environment. To address these hypotheses a business historical study is conducted using data that investigates how the pharmaceutical industry has evolved in terms of technology, knowledge, human capital and the surrounding environment. The result is an evolutionary classification that has been constructed using the cladistic method. This classification provides a system of information, evidence and assumptions that is the basis for testing the four hypotheses. The classification also provides a framework that integrates and presents the key contributions to knowledge made by this thesis: These include: • The creation of a definition for drug discovery strategy • The identification of the factors that influence the change of drug discovery strategies The creation of an evolutionary classification that identifies and arranges different types of drug discovery strategy, and reveals the characteristics of the fittest. The validation of evolution as a process for understanding change in drug discovery strategies

An Advanced ACA/BEM for Solving 2D Large-Scale Elastic Problems with Multi-Connected Domains

An advanced Boundary Element method (BEM) accelerated via Adaptive Cross Approximation (ACA) and Hierarchical Matrices (HM) techniques is presented for the solution of large-scale elastostatic problems with multi-connected domains like in fiber reinforced composite materials. Although the proposed ACA/ BEM is demonstrated for two-dimensional (2D) problems, it is quite general and it can be used for 3D problems. Different forms of ACA technique are employed for exploring their efficiency when they combined with a BEM code. More precisely, the fully and partially pivoted ACA with and without recompression are utilized, while the solution of the final linear system of equations is accelerated via an iterative GMRES solver. The proposed methodology is demonstrated with the solution of large scale, plane strain elastic problems dealing with the bending of unidirectional fiber composite plates with large numbers of periodically or randomly distributed cylindrical elastic fibers embedded in a matrix medium

“A Textbook on Ophthalmology” by Ι.L. Bistis, Athens, 1908

In 1908, John L. Bistis wrote a textbook on Ophthalmology in order to provide the students of Medicine of his time with the appropriate material and facilitate his teaching. The book is divided in two parts. The first part of the book deals with the direct and subjective eye examination and describes the methods and means used for this purpose. The second part refers to the eye anatomy and physiology, the symptoms and etiology of the diseases, as well as their prognosis and treatment. The diseases of conjuctiva, sclera and uvea are described and analyzed, the diseases of iris and ciliary body are defined and the surgical operations on iris are mentioned. Useful scientific information is provided about the diseases of choroid, of vitreous body, retina and the optic nerve. Glaucoma, eyelid and lacrymal apparatus diseases are extensively described as well as kinetic eye disorders and orbital diseases. The book concludes with the description of the refractive er­rors and the ocular adaptation disorders

Value creation through knowledge sharing in virtual community of practice

Value creation through knowledge sharing in virtual community of practic

Influence of Intraocular Lens Asphericity and Blue Light Filtering on Visual Outcome, Contrast Sensitivity, and Aberrometry after Uneventful Cataract Extraction

Purpose: To evaluate the effect of asphericity and blue light filter (BLF) of three different intraocular lenses (IOLs) on the visual performance, second- and third-order aberrations (defocus, coma, trefoil), and contrast sensitivity after uneventful cataract surgery. Methods: One hundred and twenty eyes of 60 patients with clinically significant cataract were randomly assigned to receive one of the three IOL types: Bioline Yellow Accurate (aspheric, with BLF, i-medical, Germany), BioAcryl 60125 (spherical, without BLF, Biotech, France), and H65C/N (aspheric, without BLF, PhysIOL, Belgium). Each IOL was implanted in 40 eyes. Complete ophthalmologic examination, functional acuity contrast testing and wavefront analysis were performed 60 days postoperatively. Results: The mean postoperative best-corrected visual acuity (BCVA) was 0.95 ± 0.08, not differing statistically among the IOL groups (P = 0.83). Mean defocus and coma values did not yield any statistically significant difference through the IOL groups varying from –0.784 to –0.614 μm and 0.129 to 0.198 μm (P = 0.79 and 0.34, respectively). Bioline Yellow Accurate IOL presented less trefoil aberrations, 0.108 ± 0.05 μm, compared to the other two IOL types (BioAcryl [0.206 ± 0.19 μm] and Physiol [0.193 ± 0.17 μm], P < 0.05). Contrast sensitivity values did not differ among the groups under all lighting conditions. Bioline Yellow IOL showed a statistically higher loss of contrast sensitivity (between mesopic and mesopic with glare conditions) compared to the BioAcryl and PhysIOL in 12 and 3 cpd spatial frequencies, respectively (P < 0.05). Conclusion: Bioline Yellow IOL indicated lower contrast sensitivity under mesopic conditions when glare was applied but resulted in less trefoil aberrations after uneventful cataract surgery. No further differences were noted in postoperative visual performance among three IOL groups

Greek Translation and Cultural Adaptation of the Short Version of the Maastricht Utrecht Adherence in Hypertension Questionnaire

Background: The recently published short version of the Maastricht Utrecht Adherence in Hypertension (MUAH) questionnaire (MUAH-16) suggests that MUAH-16 better represents a patient's adherence to antihypertensive medication than the original MUAH questionnaire. Objective: The aim of our study was the cultural adaptation and validation of the short MUAH-16 questionnaire in the Greek population. Methods: 10 patients were involved in the process of translation and cultural adaptation of MUAH-16, providing feedback on the final version, which was then administered to 100 patients. All patients received at least one antihypertensive drug during the last three months and were followed in the Hypertension-24h ABPM ESH Center of Excellence, Outpatient Clinic for the Treatment of Hypertension in the 3rd Internal Medicine Department of Papageorgiou General Hospital of Thessaloniki. Results: A factor analysis revealed a similar internal structure with four subscales that closely resembled the subscales in the original version of the questionnaire. Internal reliability indexes are equal or better than those of the original subscale structure. Conclusions: The Greek translation of the MUAH-16 is a good match for the original version with small, cultural differences. More research is needed in order to validate the proposed revised internal structure with a larger sample