Publications

In this work, ZnO thin films were investigated to sense NO2, a gas exhausted by the most common combustion systems polluting the environment. To this end, ZnO thin films were grown by RF sputtering on properly designed and patterned substrates to allow the measurement of the electrical response of the material when exposed to different concentrations of the gas. X-ray diffraction was carried out to correlate the material’s electrical response to the morphological and microstructural features of the sensing materials. Electrical conductivity measurements showed that the transducer fabricated in this work exhibits the optimal performance when heated at 200 °C, and the detection of 0.1 ppm concentration of NO2 was possible. Ab initio modeling allowed the understanding of the sensing mechanism driven by the competitive adsorption of NO2 and atmospheric oxygen mediated by heat. The combined theoretical and experimental study here reported provides insights into the sensing mechanism which will aid the optimization of ZnO transducer design for the quantitative measurement of NO2 exhausted by combustion systems which will be used, ultimately, for the optimized adjustment of combustion resulting into a reduced pollutants and greenhouse gases emission.

© 2016 The Author(s).Background: Motor vehicle collisions (MVCs) are a substantial contributor to the global burden of disease and lead to subsequent post-traumatic stress disorder (PTSD). However, the relevant literature originates in only a few countries, and much remains unknown about MVC-related PTSD prevalence and predictors. Methods: Data come from the World Mental Health Survey Initiative, a coordinated series of community epidemiological surveys of mental disorders throughout the world. The subset of 13 surveys (5 in high income countries, 8 in middle or low income countries) with respondents reporting PTSD after life-threatening MVCs are considered here. Six classes of predictors were assessed: socio-demographics, characteristics of the MVC, childhood family adversities, MVCs, other traumatic experiences, and respondent history of prior mental disorders. Logistic regression was used to examine predictors of PTSD. Mental disorders were assessed with the fully-structured Composite International Diagnostic Interview using DSM-IV criteria. Results: Prevalence of PTSD associated with MVCs perceived to be life-threatening was 2.5 {%} overall and did not vary significantly across countries. PTSD was significantly associated with low respondent education, someone dying in the MVC, the respondent or someone else being seriously injured, childhood family adversities, prior MVCs (but not other traumatic experiences), and number of prior anxiety disorders. The final model was significantly predictive of PTSD, with 32 {%} of all PTSD occurring among the 5 {%} of respondents classified by the model as having highest PTSD risk. Conclusion: Although PTSD is a relatively rare outcome of life-threatening MVCs, a substantial minority of PTSD cases occur among the relatively small proportion of people with highest predicted risk. This raises the question whether MVC-related PTSD could be reduced with preventive interventions targeted to high-risk survivors using models based on predictors assessed in the immediate aftermath of the MVCs.

Copyright © Cambridge University Press 2016Background: Research on post-traumatic stress disorder (PTSD) following natural and human-made disasters has been undertaken for more than three decades. Although PTSD prevalence estimates vary widely, most are in the 20–40{%} range in disaster-focused studies but considerably lower (3–5{%}) in the few general population epidemiological surveys that evaluated disaster-related PTSD as part of a broader clinical assessment. The World Mental Health (WMH) Surveys provide an opportunity to examine disaster-related PTSD in representative general population surveys across a much wider range of sites than in previous studies. Method: Although disaster-related PTSD was evaluated in 18 WMH surveys, only six in high-income countries had enough respondents for a risk factor analysis. Predictors considered were socio-demographics, disaster characteristics, and pre-disaster vulnerability factors (childhood family adversities, prior traumatic experiences, and prior mental disorders). Results: Disaster-related PTSD prevalence was 0.0–3.8{%} among adult (ages 18+) WMH respondents and was significantly related to high education, serious injury or death of someone close, forced displacement from home, and pre-existing vulnerabilities (prior childhood family adversities, other traumas, and mental disorders). Of PTSD cases 44.5{%} were among the 5{%} of respondents classified by the model as having highest PTSD risk. Conclusion: Disaster-related PTSD is uncommon in high-income WMH countries. Risk factors are consistent with prior research: severity of exposure, history of prior stress exposure, and pre-existing mental disorders. The high concentration of PTSD among respondents with high predicted risk in our model supports the focus of screening assessments that identify disaster survivors most in need of preventive interventions.

Background: Unexpected death of a loved one (UD) is the most commonly reported traumatic experience in cross-national surveys. However, much remains to be learned about posttraumatic stress disorder (PTSD) after this experience. The WHO World Mental Health (WMH) survey ini-tiative provides a unique opportunity to address these issues. Methods: Data from 19 WMH surveys (n = 78,023; 70.1{%} weighted response rate) were collated. Potential predictors of PTSD (respondent sociodemographics, characteristics of the death, history of prior trauma exposure, history of prior mental disorders) after a representative sample of UDs were examined using logistic regression. Simulation was used to estimate overall model strength in targeting individuals at highest PTSD risk. Results: PTSD prevalence after UD averaged 5.2{%} across surveys and did not differ signifi-cantly between high-income and low-middle income countries. Significant multivariate predictors included the deceased being a spouse or child, the respondent being female and believing they could have done something to prevent the death, prior trauma exposure, and history of prior men-tal disorders. The final model was strongly predictive of PTSD, with the 5{%} of respondents having highest estimated risk including 30.6{%} of all cases of PTSD. Positive predictive value (i.e., the pro-portion of high-risk individuals who actually developed PTSD) among the 5{%} of respondents with highest predicted risk was 25.3{%}. Conclusions: The high prevalence and meaningful risk of PTSD make UD a major public health issue. This study provides novel insights into predictors of PTSD after this experience and sug-gests that screening assessments might be useful in identifying high-risk individuals for preventive interventions.

Objective Little is known about the reproductive health or family planning needs of street-connected children and youth in resource-constrained countries. The study objective was to describe how street-connected children and youth (SCCY) in Eldoret, Kenya, perceive pregnancy. Methods This qualitative study was conducted between August 2013 and February 2014. A total of 65 SCCY aged 11–24 years were purposively sampled from the three referral points: 1) A dedicated study clinic for vulnerable children and youth at Moi Teaching and Referral Hospital (MTRH); 2) Primary locations in which street children reside known as “bases/barracks”; and 3) Street youth community-based organizations. In-depth interviews and focus group discussions were audio recorded, transcribed, and translated into English. Content analysis was performed after thematic coding by 4 independent coders. Results The majority of SCCY interviewed were male (69%) and sexually active (81.5%). None had gone beyond primary level of education. The strong desire for SCCY to go through conventional life experiences including marriage and child bearing was evident. Sub-themes around desired pregnancies included: sense of identity with other SCCY, sense of hope, male ego, lineage, source of income, and avoiding stigmatization. The desire for children was highly gendered with male SCCY more focused on their social status in the street community, while for females it was primarily for survival on the street. Female SCCY generally lacked agency around reproductive health issues and faced gender-based violence. Abortions (either assisted or self-induced), infanticide, and child abandonment were reported. Respondents described a lucrative market for babies born to SCCY and alleged that healthcare workers were known to abduct these babies following hospital deliveries. Conclusion Our findings indicate gender differences in the reasons why SCCY become pregnant and have children. We also noted gender inequalities in reproductive health decisions. SCCY friendly interventions that provide tailored reproductive health services are needed.