Designing a Compensated–Kidney Donation System

Osteochondral lesions of the talus (OLTs) are the third most common type of osteochondral lesion and can cause pain and instability of the ankle joint. Episurf Medical AB is a medical technology company that develops individualized implants for patients who are suffering from focal cartilage lesions. Episurf have recently started a project that aims to implement their implantation technique in the treatment of OLTs. This master thesis was a part of Episurf’s talus project and the main goal of the thesis was to find the optimal implantation angle of the Episurf implant when treating OLTs. The optimal implantation angle was defined as the angle that minimized the maximum equivalent (von Mises) strain acting on the implant shaft during the stance phase of a normal gait cycle. It is desirable to minimize the strain acting on the implant shaft, since a reduction of the strain can improve the longevity of the implant. To find the optimal implantation angle a finite element model of an ankle joint treated with the Episurf implant was developed. In the model an implant with a diameter of 12 millimeters was placed in the middle part of the medial side of the talar dome. An optimization algorithm was designed to find the implantation angle, which minimized the maximum equivalent strain acting on the implant shaft. The optimal implantation angle was found to be a sagittal angle of 12.5 degrees and a coronal angle of 0 degrees. Both the magnitude and the direction of the force applied to the ankle joint in the simulated stance phase seemed to influence the maximum equivalent strain acting on the implant shaft. A number of simplifications have been done in the simulation of this project, which might affect the accuracy of the results. Therefore it is recommended that further, more detailed, simulations based on this project are performed in order to improve the result accuracy.Fokala broskskador på talusbenet är den tredje vanligaste typen av fokala broskskador och kan ge upphov till smärta och instabilitet av fotleden. Episurf Medical AB är ett medicintekniskt företag som utvecklar individanpassade implantat för patienter med fokala broskskador. Episurf har nyligen påbörjat ett projekt där deras teknik ska användas i behandlingen av fokala broskskador på talusbenet. Den här masteruppsatsen var en del i Episurfs talusprojekt och dess huvudmål var att finna den optimala implantationsvinkeln av Episurfs implantat i behandlingen av fokala broskskador på talusbenet. Den optimala implanteringsvinkeln definierades som den vinkel som minimerade den effektiva von Mises-töjningen som verkade på implantatskaftet under stance-fasen i en normal gångcykel. Det är eftersträvansvärt att minimera belastningen på implantatskaftet eftersom en reducering av belastningen kan förbättra implantatets livslängd. En finita element-modell av en fotled behandlad med Episurfs implantat utvecklades för att för att finna den optimala implantationsvinkeln. I modellen placerades ett implantat med en diameter på 12 millimeter på mittendelen av talus mediala sida. En optimeringsalgoritm utformades för att finna implantationsvinkeln som minimerade den effektiva von Mises-töjningen på implantatskaftet. Den funna optimala implantationsvinkeln bestod av en vinkel på 12.5 grader i sagittalplan och en vinkel på 0 grader i koronalplan. Både storleken och riktningen på kraften som applicerats på fotleden under den simulerade stance-fasen av gångcykeln verkade påverka belastningen på implantatskaftet. Ett antal förenklingar har gjorts i projektets simuleringar, vilket kan påverka noggrannheten i resultatet. Därför rekommenderas att ytterligare, mer detaljerade simuleringar baserade på det här projektet görs för att förbättra resultatets noggrannhet

Do Repatriation Taxes Matter? Evidence from the Tax Returns of U.S. Multinationals

An open question in the literature on the taxation of multinational corporations is whether repatriation taxes influence whether the profits of foreign subsidiaries are repatriated or reinvested abroad. Theoretical models suggest that dividend remittances should not be influenced by repatriation taxes. The results of recent empirical work indicate that dividend remittances are sensitive to repatriation taxes. This paper investigates whether the empirical evidence can be reconciled with the theoretical results by recognizing that repatriation taxes on dividends may vary over time and provide firms with an incentive to time repatriations so that they occur in years when repatriation tax rates are relatively low. We use information about cross-country differences in tax rates to separately estimate the influence of permanent tax changes, as would occur due to changes in statutory tax rates, and transitory tax changes on dividend repatriations. Our data contains U.S. tax return information for a large sample of U.S. corporations and their foreign subsidiaries. We find that the permanent tax price effect is significantly different from the transitory price effect and is not significantly different from zero, while the transitory tax price effect is negative and significant. This suggests that repatriation taxes do affect dividend repatriation behavior but only to the extent that they vary over time. Previous empirical work has apparently measured the effect of timing behavior.

Letter from W. T. Randolph

Letter concerning sheep inspecting at Utah Agricultural College

Investigation of Additively Manufactured Molybdenum-tungsten-Rhenium Alloys

The process of creating metal components through additive manufacturing is changing the way different industries can avoid the shortcomings of traditional metal production. Metals such as tungsten, molybdenum, and rhenium have many advantages for different applications, especially when alloyed together. In this study, an additively manufactured alloy containing 70% molybdenum, 25% tungsten, and 5% rhenium (70Mo-25W-5Re) is tested for its strength, ductility, hardness, and porosity. The 70Mo-25W-5Re alloy is printed through Laser Powder Bed Fusion (LPBF) under different conditions such as printing speed and printing atmosphere. Additionally, the effects of post printing heat treatment are conducted to understand the advantages to its property changes. The printed alloys are subject to flexural loading and its physical characteristics are tested and observed. The alloy is found to be stronger at slower printing speeds which corresponds to a greater input energy density. Additionally, heat treatments acted to improve strength but had little effect on porosity or hardness. The benefits of the 70Mo-25W-5Re alloy have a potential for real world applications due to its ease in production. The findings of this research demonstrated how readily alloys of these elements can be studied by leveraging additive manufacturing and post processing heat treatments. This technique will encourage research into different combinations of the constituent elements to find promising compositions in the alloy space

Enrichment Procedures for Soft Clusters: A Statistical Test and its Applications

Clusters, typically mined by modeling locality of attribute spaces, are often evaluated for their ability to demonstrate ‘enrichment’ of categorical features. A cluster enrichment procedure evaluates the membership of a cluster for significant representation in pre-defined categories of interest. While classical enrichment procedures assume a hard clustering definition, in this paper we introduce a new statistical test that computes enrichments for soft clusters. We demonstrate an application of this test in refining and evaluating soft clusters for classification of remotely sensed images

An SMP Soft Classification Algorithm for Remote Sensing

This work introduces a symmetric multiprocessing (SMP) version of the continuous iterative guided spectral class rejection (CIGSCR) algorithm, a semiautomated classification algorithm for remote sensing (multispectral) images. The algorithm uses soft data clusters to produce a soft classification containing inherently more information than a comparable hard classification at an increased computational cost. Previous work suggests that similar algorithms achieve good parallel scalability, motivating the parallel algorithm development work here. Experimental results of applying parallel CIGSCR to an image with approximately 10^8 pixels and six bands demonstrate superlinear speedup. A soft two class classification is generated in just over four minutes using 32 processors

A Time-Series Analysis of U.S. Kidney Transplantation and the Waiting List: Donor Substitution Effects and "Dirty Altruism"

This paper provides an econometric analysis of the relationship between live and deceased (cadaveric) kidney donations for the United States for the period 1992:IV through 2006:II. Statistical analysis shows that increases in deceased donor transplants reduce future live donor grafts, controlling for both waiting list effects and exogenous trends. This result has important, and potentially dire, implications for efforts to reduce the organ shortage by increasing use of cadaver donors.Kidney Transplantations; Donor Substitution Effects; Dirty Altruism; Cointegration