Nano-Optomechanical Systems for Gas Chromatography.

Microgas chromatography (GC) is promising for portable chemical analysis. We demonstrate a nano-optomechanical system (NOMS) as an ultrasensitive mass detector in gas chromatography. Bare, native oxide, silicon surfaces are sensitive enough to monitor volatile organic compounds at ppm levels, while simultaneously demonstrating chemical selectivity. The NOMS is able to sense GC peaks from derivatized metabolites at physiological concentrations. This is an important milestone for small-molecule quantitation assays in next generation metabolite analyses for applications such as disease diagnosis and personalized medicine. The optical microring, which plays an important role in the nanomechanical signal transduction mechanism, can also be used as an analyte concentration sensor. Different adsorption kinetics regimes are realized at different temperatures allowing temporary condensation of the analyte onto the sensor surfaces. This effect amplifies the signal, resulting in a 1 ppb level limit of detection, without partition enhancement from absorbing media. This sensitivity bodes well for NOMS as universal, ultrasensitive detectors in micro-GC, breath analysis, and other chemical-sensing applications.

Determinants of inappropriate complementary feeding practices in infant and young children in Bangladesh: secondary data analysis of Demographic Health Survey 2007.

Suboptimal and inappropriate complementary feeding practices are one of the major causes of child undernutrition in the first 2 years of life in South Asian countries including Bangladesh. The aim of this study was to use the newly developed World Health Organization infant feeding indicators to identify the potential risk factors associated with inappropriate complementary feeding practices. We used data for 1728 children aged 6-23 months obtained from nationally representative data from the 2007 Bangladesh Demographic and Health Survey to assess the association between complementary feeding and other characteristics using multivariate models. Only 71% of infants were consuming soft, semi-solid and solid food by 6-8 months of age. In the multivariate analysis, mothers who had no education had a higher risk for not introducing timely complementary feeds [adjusted odds ratio (AOR)=2.14; 95% confidence interval (CI): 1.08-4.23, P=0.03], not meeting the minimum dietary diversity (AOR=1.69; 95% CI: 1.14-2.54, P=0.01), minimum acceptable diet (AOR=1.70, 95% CI: 1.09-2.67, P=0.02) and minimum meal frequency (AOR=1.73; 95% CI: 1.20-2.49, P=0.003) than the mothers who had secondary or higher education. Infants born in Sylhet, Chittagong and Barisal division had higher risks for not meeting minimum dietary diversity, meal frequency and acceptable diet (P<0.001). The poorest two quintiles had poor levels of minimum meal frequency but dietary quality improved with age. In Bangladesh addressing the fourth Millennium Development Goal (MDG) target will require substantial improvement in complementary feeding practices. Appropriate Infant and Young Child feeding massages should to be development and delivered through existing health system.

Comparisons of complementary feeding indicators and associated factors in children aged 6-23 months across five South Asian countries.

Improving infant and young child feeding practices will help South Asian countries achieve the Millennium Development Goal of reducing child mortality. This paper aims to compare key indicators of complementary feeding and their determinants in children aged 6-23 months across five South Asian countries - Bangladesh, India, Nepal, Pakistan and Sri Lanka. The latest Demographic and Health Survey and National Family Health Survey India data were used. The analyses were confined to last-born children aged 6-23 months - 1728 in Bangladesh, 15,028 in India, 1428 in Nepal, 2106 in Sri Lanka and 443 infants aged 6-8 months in Pakistan. Introduction of solid, semi-solid or soft foods, minimum dietary diversity, minimum meal frequency and minimum acceptable diet, and their significant determinants were compared across the countries. Minimum dietary diversity among children aged 6-23 months ranged from 15% in India to 71% in Sri Lanka, with Nepal (34%) and Bangladesh (42%) in between. Minimum acceptable diet among breastfed children was 9% in India, 32% in Nepal, 40% in Bangladesh and 68% in Sri Lanka. The most consistent determinants of inappropriate complementary feeding practices across all countries were the lack of maternal education and lower household wealth. Limited exposure to media, inadequate antenatal care and lack of post-natal contacts by health workers were among predictors of inappropriate feeding. Overall, complementary feeding practices among children aged 6-23 months need improvement in all South Asian countries. More intensive interventions are necessary targeting the groups with sup-optimal practices, while programmes that cover entire populations are being continued.

Prevalence and predicting factors of perceived stress among Bangladeshi university students using machine learning algorithms.

BACKGROUND: Stress-related mental health problems are one of the most common causes of the burden in university students worldwide. Many studies have been conducted to predict the prevalence of stress among university students, however most of these analyses were predominantly performed using the basic logistic regression (LR) model. As an alternative, we used the advanced machine learning (ML) approaches for detecting significant risk factors and to predict the prevalence of stress among Bangladeshi university students. METHODS: This prevalence study surveyed 355 students from twenty-eight different Bangladeshi universities using questions concerning anthropometric measurements, academic, lifestyles, and health-related information, which referred to the perceived stress status of the respondents (yes or no). Boruta algorithm was used in determining the significant prognostic factors of the prevalence of stress. Prediction models were built using decision tree (DT), random forest (RF), support vector machine (SVM), and LR, and their performances were evaluated using parameters of confusion matrix, receiver operating characteristics (ROC) curves, and k-fold cross-validation techniques. RESULTS: One-third of university students reported stress within the last 12 months. Students' pulse rate, systolic and diastolic blood pressures, sleep status, smoking status, and academic background were selected as the important features for predicting the prevalence of stress. Evaluated performance revealed that the highest performance observed from RF (accuracy = 0.8972, precision = 0.9241, sensitivity = 0.9250, specificity = 0.8148, area under the ROC curve (AUC) = 0.8715, k-fold accuracy = 0.8983) and the lowest from LR (accuracy = 0.7476, precision = 0.8354, sensitivity = 0.8250, specificity = 0.5185, AUC = 0.7822, k-fold accuracy = 07713) and SVM with polynomial kernel of degree 2 (accuracy = 0.7570, precision = 0.7975, sensitivity = 0.8630, specificity = 0.5294, AUC = 0.7717, k-fold accuracy = 0.7855). Overall, the RF model performs better and authentically predicted stress compared with other ML techniques, including individual and interaction effects of predictors. CONCLUSION: The machine learning framework can be detected the significant prognostic factors and predicted this psychological problem more accurately, thereby helping the policy-makers, stakeholders, and families to understand and prevent this serious crisis by improving policy-making strategies, mental health promotion, and establishing effective university counseling services.

Improving mechanical sensor performance through larger damping.

Mechanical resonances are used in a wide variety of devices, from smartphone accelerometers to computer clocks and from wireless filters to atomic force microscopes. Frequency stability, a critical performance metric, is generally assumed to be tantamount to resonance quality factor (the inverse of the linewidth and of the damping). We show that the frequency stability of resonant nanomechanical sensors can be improved by lowering the quality factor. At high bandwidths, quality-factor reduction is completely mitigated by increases in signal-to-noise ratio. At low bandwidths, notably, increased damping leads to better stability and sensor resolution, with improvement proportional to damping. We confirm the findings by demonstrating temperature resolution of 60 microkelvin at 300-hertz bandwidth. These results open the door to high-performance ultrasensitive resonators in gaseous or liquid environments, single-cell nanocalorimetry, nanoscale gas chromatography, atmospheric-pressure nanoscale mass spectrometry, and new approaches in crystal oscillator stability.

Effects of zinc supplementation as adjunct therapy on the systemic immune responses in shigellosis.

BACKGROUND: Zinc is lost during diarrheal diseases, and zinc deficiency induces intestinal morphology-altering inflammatory responses that zinc supplementation can correct. OBJECTIVE: We assessed the in vivo effect of zinc supplementation on systemic and mucosal responses in mildly to moderately malnourished (defined as <-1 but >-2 and <-2 but >-3 weight-for-height z scores, respectively, based on the National Center for Health Statistics growth reference) children with shigellosis. DESIGN: A double-blind placebo-controlled trial was conducted in Shigella flexneri-infected children aged 12-59 mo. Daily for 14 d, elemental zinc (20 mg) and multivitamins (vitamins A and D, thiamine, riboflavin, and nicotinamide) plus calcium were given at twice the US recommended dietary allowance to the zinc group (n=28), and multivitamins plus calcium were given to the control group (n=28). All subjects received standard antibiotic therapy. RESULTS: There was no significant interaction between zinc supplementation and time, but zinc supplementation showed a significant effect on serum zinc concentrations. With a >or=4-fold increase in serum shigellacidal antibody titers from baseline used as the cutoff, the proportion of children with shigellacidal antibody response was greater in the zinc group than in the control group (P<0.03). There was a significant (P=0.02) treatment x time interaction for the proportions of circulating CD20+ and CD20+CD38+ cells, which were higher on day 7 in the zinc group than in the control group (P<0.007). No effect was seen on histopathologic features or the expression of innate and inflammatory mediators in the rectum. CONCLUSION: Adjunct therapy with zinc during acute shigellosis significantly improved seroconversion to shigellacidal antibody response and increased the proportions of circulating B lymphocytes and plasma cells.

Efficacy of zinc in young infants with acute watery diarrhea.

BACKGROUND: Recent studies reported that zinc significantly reduced the duration and volume of acute watery diarrhea in children aged > or = 4 mo, but there were no data specifically on infants aged < 6 mo. OBJECTIVE: This study investigated the effect of zinc on the duration of illness and the stool quantity in acute watery diarrhea of infants aged 1-6 mo by comparing a 20 mg Zn/d dose with a 5 mg Zn/d dose. DESIGN: Infants hospitalized with at least some dehydration (by World Health Organization classification) were enrolled in a double-blind, randomized, placebo-controlled trial. Infants were randomly assigned to receive 20 mg Zn (acetate)/d, 5 mg Zn/d, or placebo for the duration of illness. RESULTS: Two hundred seventy-five infants were enrolled between 20 September 1998 and 18 December 2000. Neither diarrhea duration nor mean stool volume differed between groups. There were no significant differences in fluid intake, the need for unscheduled intravenous fluid, weight gain, or vomiting rates between the groups. CONCLUSIONS: Zinc supplementation did not affect diarrhea duration or stool volume in young infants. Young infants tolerated both zinc doses. A beneficial effect on subsequent illness cannot be ruled out.

Sexually harassing behavior against adolescent girls in rural Bangladesh: implications for achieving millennium development goals.

This study examines the extent and type of sexually harassing behavior or intimidations unmarried adolescent girls experienced on their way to school, college or social visits and type of perpetrators in victims' view in rural Bangladesh using data of the 2004 National Nutrition Programme baseline survey. The survey collected self-reported data on sexual harassments of 5,106 girls aged 13-19 years selected randomly. Results reveal that gendered harassments were experienced by 35% of the girls, unwanted sexual attentions by 34%, and sexual intimidations by 14%, yielding prevalence of sexual harassments of any type 43%. Higher girls' education and household economic status heightened their risks of being harassed. Perpetrators were male young spoilt bullies (64%), neighborhood youths (30%), students (22%) and hoodlums (6%). High prevalence of sexual harassments mirrors vulnerability of adolescent girls in the community and deserves to be tackled to achieve millennium development goals (MDGs) in gender equality in health and social development.