Analysis of the Self-heating Effect on Unfilled Poly(Methyl Methacrylate) Due to Cyclic Behavior

Poly(methyl methacrylate, (PMMA) has been implemented as part of the supporting structure in complete hip and knee replacements since the 1950s. Known as bone cement while in the body, PMMA is known to undergo compressive and tensile stresses that wear down the bio-compatible barrier and cause pieces to come loose inside the human body. These pieces are then attacked by the body’s own nervous system, leading to inflammation, and eventually necessitating replacement. It has been documented that under cyclic loading PMMA can reach temperatures that start to degrade its tensile capabilities. In this study the potential cause of self-heating was examined via ASTM D638 type I dog bone samples. These specimens underwent cyclic tension-tension tests run on an Instron 8801 tensile tester at varying frequencies for a total of 10,000 cycles each. Digital image correlation (DIC) was implemented to analyze displacement of the gage section as well as to calculate strain. At the same time thermography images were taken and then compared with DIC to ascertain whether localized strain would be an indicator for any localized thermal activity. The same was done for a second set of tests where a stress concentration, in the form of a 2.78 mm hole was introduced into the center of the dog bone sample. The introduction of the hole in the specimen highlighted the role that stress concentrators have in self heating. While there was little correlation for the non-holed specimens between concentrated areas of strain and localized thermal activity, the holed specimens correlated extremely well between where the strain had localized around the hole and the self-heating had similarly localized

Special issue on microscopic image processing

Cataloged from PDF version of article

First Demonstration of a Pixelated Charge Readout for Single-Phase Liquid Argon Time Projection Chambers

Liquid Argon Time Projection Chambers (LArTPCs) have been selected for the future long-baseline Deep Underground Neutrino Experiment (DUNE). To allow LArTPCs to operate in the high-multiplicity near detector environment of DUNE, a new charge readout technology is required. Traditional charge readout technologies introduce intrinsic ambiguities, combined with a slow detector response, these ambiguities have limited the performance of LArTPCs, until now. Here, we present a novel pixelated charge readout that enables the full 3D tracking capabilities of LArTPCs. We characterise the signal to noise ratio of charge readout chain, to be about 14, and demonstrate track reconstruction on 3D space points produced by the pixel readout. This pixelated charge readout makes LArTPCs a viable option for the DUNE near detector complex.Comment: 13 pages, 9 figure

Business cycles, international trade and capital flows: Evidence from Latin America

This paper adopts a flexible framework to assess both short- and long-run business cycle linkages between six Latin American (LA) countries and the four largest economies in the world (namely the US, the Euro area, Japan and China) over the period 1980:I-2011:IV. The result indicate that within the LA region there are considerable differences between countries, success stories coexisting with extremely vulnerable economies. They also show that the LA region as a whole is largely dependent on external developments, especially in the years after the great recession of 2008 and 2009. The trade channel appears to be the most important source of business cycle comovement, whilst capital flows are found to have a limited role, especially in the very short run

The influence of COMT Val158Met genotype on the character dimension cooperativeness in healthy females

Objectives: Although the Val(158)Met catechol-O-methyltransferase (COMT) gene has been linked with the temperament dimension Novelty Seeking (NS), new insights in this polymorphism might point to a major role for character features as well. Given that individual life experiences may influence Val(158) and Met(158) allele carriers differently it has been suggested that the character trait cooperativeness could be implicated. Case report: A homogeneous group of eighty right-handed Caucasian healthy female university students were assessed with the TCI and genotyped for the COMT Val(158)Met polymorphism (rs4680). Gene determination showed that eighteen were Val(158) homozygotes, forty-four Val/Met(158) heterozygotes, and eighteen were Met(158) homozygotes. All were within the same age range and never documented to have suffered from any neuropsychiatric illness. Bonferroni corrected non-parametric analyses showed that only for the character scale cooperativeness Val(158) homozygotes displayed significant higher scores when compared to Met(158) homozygotes. No significant differences on cooperativeness scores were found between Val(158) and Val/Met(158) carriers or between Met(158) and Val/Met(158) carriers. No differences were observed for the COMT Val(158) Met polymorphism and the other temperament and character scales. Conclusions: Our findings support the assumption that the Val(158)Met single nucleotide polymorphism (SNP) influences character traits and not only temperament. Our results add to the notion that Val(158) homozygotes are considered to be helpful and empathic and it suggest that these cooperativeness character traits are related to the dopaminergic system

Prevalence and distribution of the fabella: a radiographic study in Turkish subjects

Background: The purpose of this study is to examine the plain knee radiographs in Turkish subjects in order to determine the prevalence of the fabella and analyse the differences between age, gender, laterality and its symmetry pattern. Materials and methods: Bilateral antero-posterior and lateral knee radiographs of 500 patients (250 male and 250 female subjects, 1000 knee radiographs) were randomly selected from the clinical database and retrospectively evaluated. Data on patient age, gender, and knee laterality (right–left) were evaluated from hospital records. The differences between the sesamoid bones at a particular location and the side, sex and age groups were analysed. Results: The overall prevalence of the fabella (unilateral or bilateral) was 22.8% (114 subjects). The fabella was present unilaterally in 38 (7.6%) subjects, while it was present bilaterally in 76 (15.2%) subjects. The prevalence of the fabella was similar between the body sides. The prevalence of the fabella was also similar between genders (unilateral or bilateral cases) and age groups. Conclusions: We examined the prevalence, symmetry pattern, age and gender differences in Turkish population. It is the first study performed on Turkish population with the largest sample in current literature. Prevalence of fabella is found to be 22.8% which is quite similar with other Caucasian ethnic populations