Virtual Reality Prototype of a Linear Accelerator Simulator for Oncological Radiotherapy Training

Learning to operate medical equipment is one of the essential skills for providing efficient treatment to patients. One of the current problems faced by many medical institutions is the lack or shortage of specialized infrastructure for medical practitioners to conduct hands-on training. Medical equipment is mostly used for patients, limiting training time drastically. Virtual simulation can help alleviate this problem by providing the virtual embodiment of the medical facility in an affordable manner. This paper reports the current results of an ongoing project aimed at providing virtual reality-based technical training on various medical equipment to radiophysicist trainees. In particular, we introduce a virtual reality (VR) prototype of a linear accelerator simulator for oncological radiotherapy training. The paper discusses the main challenges and features of the VR prototype, including the system design and implementation. A key factor for trainees’ access and usability is the user interface, particularly tailored in our prototype to provide a powerful and versatile yet friendly user interaction

Effect of interstitial Li + ion and vacant site Li + ion on the properties of novel Li 2.05 ZnAl 0.05 Si 0.95 O 4 and Li 1.95 Zn 0.95 Cr 0.05 SiO 4 ceramic electrolytes

Lisicon-typeceramic electrolytes, Li2.05ZnAl0.05Si0.95O4 (interstitial Li-ion) and Li1.95Zn0.95Cr0.05SiO4 (Li-ion vacant site) were synthesized by sol gel method. X-ray diffraction was applied to investigate the phase, structure and unit cell parameters of both solid electrolytes. Complex impedance spectroscopy was carried out in the 10 Hz–10 MHzfrequency range and temperature range from 303–773 K to study the electrical properties of the electrolytes. Both compounds were indexed to the monoclinic unit cell in the space group P21/m. Li2.05ZnAl0.05Si0.95O4 compound gave slightly higher total conductivity values of 3.39×10−5 S cm−1 at ambient temperature and 1.03×10−4 S cm−1 at 773 K compared to Li1.95Zn0.95Cr0.05SiO4 which showed total conductivity values of 4.17×10−6 S cm−1 at ambient temperature and 4.01×10−5 S cm−1 at 773 K. It’s evident that, the Li2.05ZnAl0.05Si0.95O4 yielded a compound containing a greater number of ions with higher mobility compared to the Li1.95Zn0.95Cr0.05SiO4 compound. Linear sweep voltammetry results demonstrated that the Li1.95Zn0.95Cr0.05SiO4 and Li2.05ZnAl0.05Si0.95O4 ceramic electrolytes were electrochemically stable up to 2.7 V versus a Li/Li+

Effects of Mg2+ interstitial ion on the properties of Mg0.5+x/2Si2-xAlx(PO4)3 ceramic electrolytes

Nasicon type, Mg0.5+x/2Si2-xAlx(PO4)3 was synthesized using citric acid assisted sol-gel method. The X-ray diffraction was applied to investigate the effect of extra Mg2+ interstitial ion on the phase, unit cell parameters and structure of the samples. The Mg0.625Si1.75Al0.25(PO4)3 sample exhibited highest bulk conductivity value of 1.54 × 10−4 S cm−1 at ambient temperature. The frequency dependence of the σac of these ceramic electrolytes follows the universal power law variation, σac (ω) = σo + Aωα. The conductivity parameters such as hopping frequencies, charge carrier concentration and mobile ion concentration proved that the increase in conductivity with x was due to the existence of Mg2+ interstitial ions. The experiment results also revealed that the dielectric constant and dielectric loss decreased with frequency. The Mg0.625Si1.75Al0.25(PO4)3 was found to be electrochemically stable up to 2.51 V at ambient temperature. Keywords: Ceramic, Electrolyte, Mg electrolyte, Interstitial ion, Nasico

Evaluation of gram-chromotrope kinyoun staining technique: its effectiveness in detecting microsporidial spores in fecal specimens

This study was conducted to evaluate the modification of the usual Gram-chromotrope staining technique developed in-house known as Gram-chromotrope Kinyoun (GCK) in comparison with the Weber Modified Trichrome (WMT) staining technique; as the reference technique. Two hundred and ninety fecal specimens received by the Microbiology Diagnostic Laboratory of Hospital Universiti Kebangsaan Malaysia were examined for the presence of microsporidial spores. The sensitivity and specificity of GCK compared to the reference technique were 98 and 98.3, respectively. The positive and negative predictive values were 92.5 and 99.6, respectively. The agreement between the reference technique and the GCK staining technique was statistically significant by Kappa statistics (K = 0.941, P < 0.001). It is concluded that the GCK staining technique has high sensitivity and specificity in the detection of microsporidial spores in fecal specimens. Hence, it is recommended to be used in the diagnosis of intestinal microsporidiosis. (C) 2011 Elsevier Inc. All rights reserved

A comparison of leaf and petal senescence in wallflower reveals common and distinct patterns of gene expression and physiology

Petals and leaves share common evolutionary origins but perform very different functions. However, few studies have compared leaf and petal senescence within the same species. Wallflower (Erysimum linifolium), an ornamental species closely related to Arabidopsis (Arabidopsis thaliana), provide a good species in which to study these processes. Physiological parameters were used to define stages of development and senescence in leaves and petals and to align these stages in the two organs. Treatment with silver thiosulfate confirmed that petal senescence in wallflower is ethylene dependent, and treatment with exogenous cytokinin and 6-methyl purine, an inhibitor of cytokinin oxidase, suggests a role for cytokinins in this process. Subtractive libraries were created, enriched for wallflower genes whose expression is up-regulated during leaf or petal senescence, and used to create a microarray, together with 91 senescence-related Arabidopsis probes. Several microarray hybridization classes were observed demonstrating similarities and differences in gene expression profiles of these two organs. Putative functions were ascribed to 170 sequenced DNA fragments from the libraries. Notable similarities between leaf and petal senescence include a large proportion of remobilization-related genes, such as the cysteine protease gene SENESCENCE-ASSOCIATED GENE12 that was up-regulated in both tissues with age. Interesting differences included the up-regulation of chitinase and glutathione S-transferase genes in senescing petals while their expression remained constant or fell with age in leaves. Semiquantitative reverse transcription-polymerase chain reaction of selected genes from the suppression subtractive hybridization libraries revealed more complex patterns of expression compared with the array data. © 2008 American Society of Plant Biologists