Structure-property relationships of inorganic semiconductor materials

Ph.DDOCTOR OF PHILOSOPH

Structured ZnO-based contacts deposited by non-reactive rf magnetron sputtering on ultra-thin SiO2/Si through a stencil mask

In this paper, we study the localized deposition of ZnO micro and nanostructures deposited by non-reactive rf-magnetron sputtering through a stencil mask on ultra-thin (10 nm) SiO2 layers containing a single plane of silicon nanocrystals (NCs), synthetized by ultra-low energy ion implantation followed by thermal annealing. The localized ZnO-deposited areas are reproducing the exact stencil mask patterns. A resistivity of around 5×10−3 Ω cm is measured on ZnO layer. The as-deposited ZnO material is 97% transparent above the wavelength at 400 nm. ZnO nanostructures can thus be used as transparent electrodes for Si NCs embedded in the gate-oxide of MOS devices

Patient-defined recovery from depression in primary care in Singapore

Research on consumer-defined recovery from mental illness has been criticised for a lack of quantitative analyses and conceptual clarity. This study aims to address this by statistically testing the possible associations between a major model of the stages of recovery and five postulated processes that have been theorised to drive recovery. Eighty-eight participants, who attended psychological consultation for depression at the National Healthcare Group Polyclinics, were recruited. Questionnaires on recovery stages and the five recovery processes were directly administered, while the measure for depressive symptoms were extracted from case file data. Results showed that the five recovery processes were associated with the recovery stages in a manner that supported this recovery model for patients with depression in primary care. However, most of these associations became nonsignificant when the severity of depression was controlled for. Thus, further research is needed to precisely identify the impact of the severity of depression on the patients’ experience of their recovery journeys

Predictors of motivation for type 2 diabetes mellitus self management of patients in primary care in Singapore

Background: Diabetes is among the top 10 causes of death in Singapore, which has the second-highest proportion of diabetics among all developed nations. Diabetic patients’ self-management is often driven by their perceptions about their own chronic condition. This study explored specific aspects of patients’ (1) cognitive appraisal, (2) emotional distress and (3) a motivational measure in relation to their diabetic condition and attitude toward self-management. Methods: Seventy adult participants (41 female and 29 male) with type-2 diabetes were recruited in this cross-sectional study from patients who sought psychological consultation at polyclinics. The questionnaires administered were (1) Brief Illness Perception Questionnaire, (2) Diabetes Distress Scale, (3) Generalised Anxiety Disorder-7, (4) Insomnia Severity Index, (5) Patient Health Questionnaire-9, (6) Readiness-to-Change Ruler and (7) Sheehan Disability Scale. Results: Multiple regression analysis showed that severity of insomnia symptoms (β = -.26 , p < .05), emotional distress of diabetes (β = -.48 , p < .05), interpersonal distress of diabetes (β = -.35 , p < .05), total distress of diabetes (β = .58 , p < .05), and perception of personal control over diabetes (β = .-.30, p < .05) were significantly associated with reported motivation for engaging in diabetes self-management (R2 = .26, F(5, 62) = 4.26, p < 0.01). Conclusion: Insomnia, emotional distress and perception of personal control over diabetes significantly predicted patients’ reported motivation for diabetes self-management. It may be more productive for clinicians to focus their interventions on these particular aspects of diabetic patients’ experience in promoting self-management behaviour. Future studies may involve (1) the measurement of actual self-management behaviour beyond participants’ report of their motivation to engage in such desirable behavior and (2) qualitative approaches for understanding subjective dimensions of “insomnia,” “distress” and “personal control” in relation to diabetes self-management

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

Peer reviewe

Study of W boson production in pPb collisions at vsNN = 5.02 TeV

The first study of W boson production in pPb collisions is presented, for bosons decaying to a muon or electron, and a neutrino. The measurements are based on a data sample corresponding to an integrated luminosity of 34.6 nb-1 at a nucleon–nucleon centre-of-mass energy of vsNN = 5.02 TeV, collected by the CMS experiment. The W boson differential cross sections, lepton charge asymmetry, and forward–backward asymmetries are measured for leptons of transverse momentum exceeding 25 GeV/c, and as a function of the lepton pseudorapidity in the |?lab| < 2.4range. Deviations from the expectations based on currently available parton distribution functions are observed, showing the need for including W boson data in nuclear parton distribution global fits

Ki67 expression has prognostic significance in relation to human papillomavirus status in oropharyngeal squamous cell carcinoma

Background. Human papillomavirus (HPV) is the major predictor of outcome in oropharyngeal squamous cell carcinoma (OSCC) but the disease is heterogeneous and there is limited understanding of the prognostic significance of other molecular markers in relation to HPV. This multi-institutional, retrospective study examined the prognostic significance of Ki67 expression in association with HPV status in OSCC. Methods. The 105 patients recruited had a median follow-up of 70 months. Tumor HPV status was determined by HPV E6-targeted multiplex real-time polymerase chain reaction/p16 semiquantitative immunohistochemistry and Ki67 expression by semiquantitative immunohistochemistry. Determinants of recurrence and mortality hazards were modelled using Cox regression with censoring at dates of last follow-up. Results. HPV and Ki67 positivity rates were 46 and 44 %, respectively. HPV-positive cancers were more likely to be Ki67-positive. On multivariate analysis, both HPV and Ki67 were predictors of outcome. Ki67-positive cancers were associated with a 3.13-fold increased risk of disease-related death compared with Ki67-negative cancers. Among HPV-negative patients, Ki67-positive disease was associated with 5.6-fold increased risk of oropharyngeal cancer-related death (p = 0.002), 5.5-fold increased risk of death from any cause (p = 0.001), and 2.9-fold increased risk of any event (p = 0.013). The risk of locoregional failure was lowest in patients with HPV-positive/Ki67-positive cancers. Conclusions.Ki67 predicts disease-related death in oropharyngeal cancer independent of HPV status. A combination of Ki67 and HPV status provides improved prognostic information relative to HPV status alone. Our data suggest, for the first time, that Ki67 status has prognostic value, particularly in HPV-negative oropharyngeal cancer