The dependence of computed tomography number to relative electron density conversion on phantom geometry and its impact on planned dose

A computed tomography number to relative electron density (CT-RED) calibration is performed when commissioning a radiotherapy CT scanner by imaging a calibration phantom with inserts of specified RED and recording the CT number displayed. In this work, CT-RED calibrations were generated using several commercially available phantoms to observe the effect of phantom geometry on conversion to electron density and, ultimately, the dose calculation in a treatment planning system. Using an anthropomorphic phantom as a gold standard, the CT number of a material was found to depend strongly on the amount and type of scattering material surrounding the volume of interest, with the largest variation observed for the highest density material tested, cortical bone. Cortical bone gave a maximum CT number difference of 1,110 when a cylindrical insert of diameter 28 mm scanned free in air was compared to that in the form of a 30 × 30 cm2 slab. The effect of using each CT-RED calibration on planned dose to a patient was quantified using a commercially available treatment planning system. When all calibrations were compared to the anthropomorphic calibration, the largest percentage dose difference was 4.2 % which occurred when the CT-RED calibration curve was acquired with heterogeneity inserts removed from the phantom and scanned free in air. The maximum dose difference observed between two dedicated CT-RED phantoms was ±2.1 %. A phantom that is to be used for CT-RED calibrations must have sufficient water equivalent scattering material surrounding the heterogeneous objects that are to be used for calibration.

Spirituality in Indian University students and its associations with socioeconomic status, religious background, social support, and mental health

The present study aimed to understand spirituality and its relationships with socioeconomic status (SES), religious background, social support, and mental health among Indian university students. It was hypothesized that: - (1) female university students will be more spiritual than male university students, - (2) four domains of spirituality will differ significantly across socioeconomic and religious background of the university students in addition to social support, and; - (3) there will be a positive relationship between spirituality and mental health of university students, irrespective of gender. A group of 475 postgraduate students aged 20–27 years, 241 males and 234 females, from various disciplines of Pondicherry University, India, participated in the study. Students’ background was collected using a structured questionnaire. Overall spirituality and its four dimensions were measured using the Spirituality Attitude Inventory, while mental health status was estimated based on scores of the psychological subscale of the WHO Quality of Life Questionnaire. Female students were significantly more spiritual than male students, particularly in spiritual practice and sense of purpose/connection. Hindu religion and lower family income were associated with lower spirituality. Higher spirituality was associated with congenial family environment and more support from teachers and classmates. There was a strong association between overall spirituality and two spirituality domains (spiritual belief and sense of purpose/connection) with better mental health. Findings suggest an opportunity for open dialogue on spirituality for university students as part of their mental health and support services that fosters a positive mind set and enhancement of resilience.

Molecular dynamics simulations of CXCL-8 and its interactions with a receptor peptide, heparin fragments, and sulfated linked cyclitols

CXCL-8 (Interleukin 8) is a CXC chemokine with a central role in the human immune response. We have undertaken extensive in silico analyses to elucidate the interactions of CXCL-8 with its various binding partners, which are crucial for its biological function. Sequence and structure analyses showed that residues in the thirdq β-sheet and basic residues in the heparin binding site are highly variable, while residues in the second β-sheet are highly conserved. Molecular dynamics simulations in aqueous solution of dimeric CXCL-8 have been performed with starting geometries from both X-ray and NMR structures showed shearing movements between the two antiparallel C-terminal helices. Dynamic conservation analyses of these simulations agreed with experimental data indicating that structural differences between the two structures at quaternary level arise from changes in the secondary structure of the N-terminal loop, the 310-helix, the 30s, 40s, and 50s loops and the third β-sheet, resulting in a different interhelical separation. Nevertheless, the observation of these different states indicates that CXCL-8 has the potential to undergo conformational changes, and it seems likely that this feature is relevant to the mode of binding of glycosaminoglycan (GAG) mimetics such as cyclitols. Simulations of the receptor peptide fragment−CXCL-8 complex identified several specific interactions of the receptor peptide with CXCL-8 that could be exploited in the structure-based design of competitive peptides and nonpeptidic molecules targeting CXCL-8 for combating inflammatory diseases. Simulations of the CXCL-8 dimer complexed with a 24-mer heparin fragment and of the CXCL-8−receptor peptide complex revealed that Arg60, Lys64, and Arg68 in the dimer bind to cyclitols in a horseshoe pattern, defining a region which is spatially distinct from the receptor binding site. There appears to be an optimum number of sulfates and an optimum length of alkyl spacers required for the interaction of cyclitol inhibitors with the dimeric form of CXCL-8. Calculation of the binding affinities of cyclitol inhibitors reflected satisfactorily the ranking of experimentally determined inhibitory potencies. The findings of these molecular modeling studies will help in the search for inhibitors which can modulate various CXCL-8 biological activities and serve as an excellent model system to study CXC-inhibitor interactions.

The Behavior of Hydroxyl Units of Synthetic Goethite and its Dehydroxylated Product Hematite

The behavior of the hydroxyl units of synthetic goethite and its dehydroxylated product hematite was characterized using a combination of Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) during the thermal transformation over a temperature range of 180-270 degrees C. Hematite was detected at temperatures above 200 degrees C by XRD while goethite was not observed above 230 degrees C. Five intense OH vibrations at 3212-3194, 1687-1674, 1643-1640, 888-884 and 800-798 cm(-1), and a H2O vibration at 3450-3445 cm(-1) were observed for goethite. The intensity of hydroxyl stretching and bending vibrations decreased with the extent of dehydroxylation of goethite. Infrared absorption bands clearly show the phase transformation between goethite and hematite: in particular. the migration of excess hydroxyl units from goethite to hematite. Two bands at 536-533 and 454-452 cm(-1) are the low wavenumber vibrations of Fe-O in the hematite structure. Band component analysis data of FTIR spectra support the fact that the hydroxyl units mainly affect the a plane in goethite and the equivalent c plane in hematite.

The Scored Patient-Generated Subjective Global Assessment (PG-SGA) and its Association with Quality of Life in Ambulatory Patients Receiving Radiotherapy

OBJECTIVE: To evaluate the scored Patient-generated Subjective Global Assessment (PG-SGA) tool as an outcome measure in clinical nutrition practice and determine its association with quality of life (QoL). DESIGN: A prospective 4 week study assessing the nutritional status and QoL of ambulatory patients receiving radiation therapy to the head, neck, rectal or abdominal area. SETTING: Australian radiation oncology facilities. SUBJECTS: Sixty cancer patients aged 24-85 y. INTERVENTION: Scored PG-SGA questionnaire, subjective global assessment (SGA), QoL (EORTC QLQ-C30 version 3). RESULTS: According to SGA, 65.0% (39) of subjects were well-nourished, 28.3% (17) moderately or suspected of being malnourished and 6.7% (4) severely malnourished. PG-SGA score and global QoL were correlated (r=-0.66, P<0.001) at baseline. There was a decrease in nutritional status according to PG-SGA score (P<0.001) and SGA (P<0.001); and a decrease in global QoL (P<0.001) after 4 weeks of radiotherapy. There was a linear trend for change in PG-SGA score (P<0.001) and change in global QoL (P=0.003) between those patients who improved (5%) maintained (56.7%) or deteriorated (33.3%) in nutritional status according to SGA. There was a correlation between change in PG-SGA score and change in QoL after 4 weeks of radiotherapy (r=-0.55, P<0.001). Regression analysis determined that 26% of the variation of change in QoL was explained by change in PG-SGA (P=0.001). CONCLUSION: The scored PG-SGA is a nutrition assessment tool that identifies malnutrition in ambulatory oncology patients receiving radiotherapy and can be used to predict the magnitude of change in QoL.

IT professionals' experience of ethics and its implications for IT education

This study investigates variation in IT professionals' experience of ethics with a view to enhancing their formation and support. This is explored through an examination of the experience of IT, IT professional ethics and IT professional ethics education. The study's principal contribution is the empirical study and description of IT professionals' experience of ethics. The empirical phase is preceded by a review of conceptions of IT and followed by an application of the findings to IT education. The study's empirical findings are based on 30 semi-structured interviews with IT professionals who represent a wide demographic, experience and IT sub-discipline range. Their experience of ethics is depicted as five citizenships: Citizenship of my world, Citizenship of the corporate world, Citizenship of a shared world, Citizenship of the client's world and Citizenship of the wider world. These signify an expanding awareness, which progressively accords rights to others and defines responsibility in terms of others. The empirical findings inform a Model of Ethical IT. This maps an IT professional space increasingly oriented towards others. Such a model provides a conceptual tool, available to prompt discussion and reflection, and which may be employed in pursuing formation aimed at experiential change. Its usefulness for the education of IT professionals with respect to ethics is explored. The research approach employed in this study is phenomenography. This method seeks to elicit and represent variation of experience. It understands experience as a relationship between a subject (IT professionals) and an object (ethics), and describes this relationship in terms of its foci and boundaries. The study's findings culminate in three observations, that change is indicated in the formation and support of IT professionals in: 1. IT professionals' experience of their discipline, moving towards a focus on information users; 2. IT professionals' experience of professional ethics, moving towards the adoption of other-centred attitudes; and 3. IT professionals' experience of professional development, moving towards an emphasis on a change in lived experience. Based on these results, employers, educators and professional bodies may want to evaluate how they approach professional formation and support, if they aim to promote a comprehensive awareness of ethics in IT professionals.