Factorial structure of the Chinese version of the 12-item General Health Questionnaire in adolescents

Aims. To evaluate the underlying factor structure of the Chinese version of General Health Questionnaire-12 using exploratory and confirmatory factor analyses in Chinese adolescents and find out which factor model proposed by previous empirical research is the best-fit model. Background. The 12-item General Health Questionnaire has been extensively used with adolescents in the West. Yet, it has not been used with adolescents in a Hong Kong Chinese context. Design. A cross-sectional study was employed. Method. Chinese students between the ages of 12-19 from four secondary schools were invited to participate in the study using the multiple-stage stratified random sampling method during the period from December 2007-February, 2008. The total sample size included in the final analysed was 1883. Results. The General Health Questionnaire-12 was found to be internally consistent. The results of exploratory factor analysis showed that there are two factors underlying the General Health Questionnaire-12. Of nine factor models were tested by means of confirmatory factor analysis, only three factor model: the eight-item two-factor model, 12-item three-factor model and 10-item two-factor model, demonstrated good model fit across all model fit indices. Conclusion. This study addressed a gap in the literature by evaluating the factorial structure of the Chinese version of General Health Questionnaire-12 using exploratory and confirmatory factor analyses in Chinese adolescents. The findings revealed that the eight-item two-factor model is the best-fit model. Relevance to clinical practice. The adolescent mental health problem is alarming and aggravating and warrants special attention. It is essential for community nurses to differentiate psychological distress in adolescents and to identify those adolescents who are at a higher risk of suffering from mental health problems. The availability of a valid and reliable instrument that measures adolescents' psychological distress is crucial before any nursing interventions to promote their mental health can be appropriately planned, implemented and evaluated. © 2009 Blackwell Publishing Ltd.postprin

Axially graded heteroepitaxy and Raman spectroscopic characterizations of Si1-xGex nanowires

We report the axially graded heteroepitaxy of Si1-xGex nanowires, by the kinetic controls of the Au-catalytic decomposition of precursors during chemical vapor syntheses. Transmission electron microscope studies demonstrate that the relative composition of Si and Ge is continuously graded along the uniformly thick nanowires, sharing the same crystal structures with the continuously varying lattices. We also employed a confocal Raman scattering imaging technique, and showed that the local variations in Raman phonon bands, specific to Si and Ge alloying (nu(Si-Si), nu(Si-Ge), and nu(Ge-Ge)), can be spatially and spectrally resolved along the individual nanowires, within the spatial resolution of similar to 500 nm. (c) 2008 American Institute of Physics.open111213Nsciescopu

Quantum fluctuations can promote or inhibit glass formation

The very nature of glass is somewhat mysterious: while relaxation times in glasses are of sufficient magnitude that large-scale motion on the atomic level is essentially as slow as it is in the crystalline state, the structure of glass appears barely different than that of the liquid that produced it. Quantum mechanical systems ranging from electron liquids to superfluid helium appear to form glasses, but as yet no unifying framework exists connecting classical and quantum regimes of vitrification. Here we develop new insights from theory and simulation into the quantum glass transition that surprisingly reveal distinct regions where quantum fluctuations can either promote or inhibit glass formation.Comment: Accepted for publication in Nature Physics. 22 pages, 3 figures, 1 Tabl

‘Do i care?’ young adults' recalled experiences of early adolescent overweight and obesity: a qualitative study

<p>Objective: Individual behaviour change to reduce obesity requires awareness of, and concern about, weight. This paper therefore describes how young adults, known to have been overweight or obese during early adolescence, recalled early adolescent weight-related awareness and concerns. Associations between recalled concerns and weight-, health- and peer-related survey responses collected during adolescence are also examined.</p> <p>Design: Qualitative semi-structured interviews with young adults; data compared with responses to self-report questionnaires obtained in adolescence.</p> <p>Participants: A total of 35 participants, purposively sub-sampled at age 24 from a longitudinal study of a school year cohort, previously surveyed at ages 11, 13 and 15. Physical measures during previous surveys allowed identification of participants with a body mass index (BMI) indicative of overweight or obesity (based on British 1990 growth reference) during early adolescence. Overall, 26 had been obese, of whom 11 had BMI99.6th centile, whereas 9 had been overweight (BMI=95th–97.9th centile).</p> <p>Measures: Qualitative interview responses describing teenage life, with prompts for school-, social- and health-related concerns. Early adolescent self-report questionnaire data on weight-worries, self-esteem, friends and victimisation (closed questions).</p> <p>Results: Most, but not all recalled having been aware of their overweight. None referred to themselves as having been obese. None recalled weight-related health worries. Recollection of early adolescent obesity varied from major concerns impacting on much of an individual's life to almost no concern, with little relation to actual severity of overweight. Recalled concerns were not clearly patterned by gender, but young adult males recalling concerns had previously reported more worries about weight, lower self-esteem, fewer friends and more victimisation in early adolescence; no such pattern was seen among females. Conclusion: The popular image of the unhappy overweight teenager was not borne out. Many obese adolescents, although well aware of their overweight recalled neither major dissatisfaction nor concern. Weight-reduction behaviours are unlikely in such circumstances.</p&gt

Fabrication of Si1-xGex alloy nanowire field-effect transistors

The authors present the demonstration of nanowire field-effect transistors incorporating group IV alloy nanowires, Si1-xGex. Single-crystalline Si1-xGex alloy nanowires were grown by a Au catalyst-assisted chemical vapor synthesis using SiH4 and GeH4 precursors, and the alloy composition was reproducibly controlled in the whole composition range by controlling the kinetics of catalytic decomposition of precursors. Complementary in situ doping of Si1-xGex nanowires was achieved by PH3 and B2H6 incorporation during the synthesis for n- and p-type field-effect transistors. The availability of both n- and p-type Si1-xGex nanowire circuit components suggests implications for group IV semiconductor nanowire electronics and optoelectronics. (C) 2007 American Institute of Physics.X114125Nsciescopu

Histological response of peritoneal carcinomatosis after hyperthermic intraperitoneal chemoperfusion (HIPEC) in experimental investigations

BACKGROUND: In selected patients with peritoneal carcinomatosis from colorectal cancer prognosis can be improved by hyperthermic intraperitoneal chemotherapy (HIPEC) after cytoreductive surgery. The aim of this study was to evaluate the tumor response of peritoneal carcinomatosis in tumor-bearing rats treated with HIPEC. METHODS: CC531 colon carcinoma (2,5 × 10(6 )cells), implanted intraperitoneally in Wag/Rija rats, was treated by hyperthermic intraperitoneal chemotherapy. After 10 days of tumor growth the animals were randomized into five groups of six animals each: group I: control (n = 6), group II: sham operated animals (n = 6), group III: hyperthermic intraperitoneal perfusion (HIP) without cytostatic drugs, group IV: HIPEC with mitomycin C in a concentration of 15 mg/m(2 )(n = 6), group V: mitomycin C i.p. alone in a concentration of 10 mg/m(2 )(n = 6). After 10 days the extent of tumor spread and histological outcome were analysed by autopsy. RESULTS: All control animals developed extensive intraperitoneal tumor growth. Histological tumor load was significantly reduced in group III and group V and was lowest in group IV. In group II tumor load was significantly higher than in group I. Implanted metastases were significantly decreased in group IV compared with group I and group II. CONCLUSION: These findings indicate that HIPEC is an effective treatment for peritoneal carcinomatosis in this animal model. HIPEC reduced macroscopic and microscopic intraperitoneal tumor spread

Coverage, Continuity and Visual Cortical Architecture

The primary visual cortex of many mammals contains a continuous representation of visual space, with a roughly repetitive aperiodic map of orientation preferences superimposed. It was recently found that orientation preference maps (OPMs) obey statistical laws which are apparently invariant among species widely separated in eutherian evolution. Here, we examine whether one of the most prominent models for the optimization of cortical maps, the elastic net (EN) model, can reproduce this common design. The EN model generates representations which optimally trade of stimulus space coverage and map continuity. While this model has been used in numerous studies, no analytical results about the precise layout of the predicted OPMs have been obtained so far. We present a mathematical approach to analytically calculate the cortical representations predicted by the EN model for the joint mapping of stimulus position and orientation. We find that in all previously studied regimes, predicted OPM layouts are perfectly periodic. An unbiased search through the EN parameter space identifies a novel regime of aperiodic OPMs with pinwheel densities lower than found in experiments. In an extreme limit, aperiodic OPMs quantitatively resembling experimental observations emerge. Stabilization of these layouts results from strong nonlocal interactions rather than from a coverage-continuity-compromise. Our results demonstrate that optimization models for stimulus representations dominated by nonlocal suppressive interactions are in principle capable of correctly predicting the common OPM design. They question that visual cortical feature representations can be explained by a coverage-continuity-compromise.Comment: 100 pages, including an Appendix, 21 + 7 figure

P-value based visualization of codon usage data

Two important and not yet solved problems in bacterial genome research are the identification of horizontally transferred genes and the prediction of gene expression levels. Both problems can be addressed by multivariate analysis of codon usage data. In particular dimensionality reduction methods for visualization of multivariate data have shown to be effective tools for codon usage analysis. We here propose a multidimensional scaling approach using a novel similarity measure for codon usage tables. Our probabilistic similarity measure is based on P-values derived from the well-known chi-square test for comparison of two distributions. Experimental results on four microbial genomes indicate that the new method is well-suited for the analysis of horizontal gene transfer and translational selection. As compared with the widely-used correspondence analysis, our method did not suffer from outlier sensitivity and showed a better clustering of putative alien genes in most cases