Investigation of two heavy element scintillators by Monte-Carlo methods

The aim of this study was to estimate the influence of K-characteristic radiation on the performance of x-ray scintillating screens containing two heavy elements by Monte Carlo methods. K-characteristic radiation is produced within materials of at least one heavy (high atomic number) element. This radiation may result either in spatial resolution degradation or in emission efficiency decrease. The scintillators studied were the following: LYSO (Lu1.8Y0.2SiO5 and LuYSiO5), CsI and YTaO4. All the aforementioned scintillators have two heavy elements, thus the K-characteristic radiation of the high-Z element can produce additional K-characteristic photons on the low-Z element, resulting in further degradation. Scintillator performance was described in terms of the: (a) Probability of generation and reabsorption of a K-characteristic photon (PKR) and (b) Spatial distribution of K-characteristic radiation within the scintillator material. A custom validated Monte Carlo model was used, in order to simulate the transport of K-characteristic radiation within the above scintillator materials. Results showed that, depending on screen thickness (20-100 mg/cm2) and incident photon energy (20-80 keV) the scintillator's emission efficiency may be significantly reduced. © 2009 IOP Publishing Ltd and SISSA

Radioluminescence properties of the CdSe/ZnS Quantum Dot nanocrystals with analysis of long-memory trends

This paper reports radioluminescence properties of the CdSe/ZnS quantum dots. Three quantum dot samples were prepared with concentrations 14.2 × 10−5 mg/mL, 21.3 × 10−5 mg/mL and 28.5 × 10−5 mg/mL, respectively. The ultraviolet induced emission spectra of CdSe/ZnS dots exhibited a peak at 550 nm ranging between 450 nm and 650 nm. Discrepancies observed between 250 nm and 450 nm were attributed to the solvent and cuvette. The absolute efficiency calculated from random fractional-Gaussian luminescence segments varied. Long-memory fractional-Brownian segments were also found. The quantum dot solution with concentration of 21.3 × 10−5 mg/mL exhibited the maximum absolute efficiency value at 90 kVp. The CdSe/ZnS dots have demonstrated potential for detection of X-rays in the medical imaging energy range

A case of bilateral self-induced keratoconus in a patient with tourette syndrome associated with compulsive eye rubbing: case report

<p>Abstract</p> <p>Background</p> <p>Tourette syndrome is a neurologic disorder that is characterized by repetitive muscle contractions that produce stereotyped movements or sounds. Approximately 50% of individuals with TS also exhibit obsessive-compulsive behaviors including eye rubbing. We report a case of bilateral self-induced keratoconus in a patient with TS, associated with compulsive eye rubbing.</p> <p>Case presentation</p> <p>A 35-year-old man was first seen in our clinic as an outpatient due to rapid deterioration of vision in his right eye associated with pain and tearing, over a period of one month. Slit lamp biomicroscopy of the right eye showed a central stromal scar due to corneal hydrops. Clinical examination and corneal topography of the left eye were normal. Six months later the patient developed corneal hydrops of his left eye. During the following examinations his vision continued to deteriorate in both eyes, while a central stromal scar was forming in his left cornea. Four years after the initial examination the patient's visual acuity was no light perception in the right eye and counting fingers at 33 cm in the left eye. His right eye was phthisic.</p> <p>Conclusions</p> <p>Our patient developed a rapidly progressing bilateral corneal ectasia and phthisis of his right eye during a time period of 4 years. This unusual pattern suggests that the patient's compulsive behavior compromised both of his corneas and led to bilateral keratoconus.</p

Anti-androgens act jointly in suppressing spiggin concentrations in androgen-primed female three-spined sticklebacks - Prediction of combined effects by concentration addition

This is the post-print version of the final paper published in Aquatic Toxicology. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2013 Elsevier B.V.Increasing attention is being directed at the role played by anti-androgenic chemicals in endocrine disruption of wildlife within the aquatic environment. The co-occurrence of multiple contaminants with anti-androgenic activity highlights a need for the predictive assessment of combined effects, but information about anti-androgen mixture effects on wildlife is lacking. This study evaluated the suitability of the androgenised female stickleback screen (AFSS), in which inhibition of androgen-induced spiggin production provides a quantitative assessment of anti-androgenic activity, for predicting the effect of a four component mixture of anti-androgens. The anti-androgenic activity of four known anti-androgens (vinclozolin, fenitrothion, flutamide, linuron) was evaluated from individual concentration-response data and used to design a mixture containing each chemical at equipotent concentrations. Across a 100-fold concentration range, a concentration addition approach was used to predict the response of fish to the mixture. Two studies were conducted independently at each of two laboratories. By using a novel method to adjust for differences between nominal and measured concentrations, good agreement was obtained between the actual outcome of the mixture exposure and the predicted outcome. This demonstrated for the first time that androgen receptor antagonists act in concert in an additive fashion in fish and that existing mixture methodology is effective in predicting the outcome, based on concentration-response data for individual chemicals. The sensitivity range of the AFSS assay lies within the range of anti-androgenicity reported in rivers across many locations internationally. The approach taken in our study lays the foundations for understanding how androgen receptor antagonists work together in fish and is essential in informing risk assessment methods for complex anti-androgenic mixtures in the aquatic environment.European Commission and Natural Environment Research Council

First Evidence of Genetic Association Between AKT2 and Polycystic Ovary Syndrome

OBJECTIVE—Insulin resistance has been reported in up to 70% of women with polycystic ovary syndrome (PCOS). Physiologic and genetic data currently implicate post–insulin receptor signaling defects in substrates such as glycogen synthase kinase 3β (GSK3β). The AKT2 gene was chosen as a candidate for PCOS because its product affects glucose metabolism and mitogenic signaling, interacts with GSK3β, and mediates cell survival in the ovary