Electronic states and optical properties of PbSe nanorods and nanowires

A theory of the electronic structure and excitonic absorption spectra of PbS and PbSe nanowires and nanorods in the framework of a four-band effective mass model is presented. Calculations conducted for PbSe show that dielectric contrast dramatically strengthens the exciton binding in narrow nanowires and nanorods. However, the self-interaction energies of the electron and hole nearly cancel the Coulomb binding, and as a result the optical absorption spectra are practically unaffected by the strong dielectric contrast between PbSe and the surrounding medium. Measurements of the size-dependent absorption spectra of colloidal PbSe nanorods are also presented. Using room-temperature energy-band parameters extracted from the optical spectra of spherical PbSe nanocrystals, the theory provides good quantitative agreement with the measured spectra.Comment: 35 pages, 12 figure

A scalable hybrid decision system (HDS) for Roman word recognition using ANN SVM: Study case on Malay word recognition

An off-line handwriting recognition (OFHR) system is a computerized system that is capable of intelligently converting human handwritten data extracted from scanned paper documents into an equivalent text format. This paper studies a proposed OFHR for Malaysian bank cheques written in the Malay language. The proposed system comprised of three components, namely a character recognition system (CRS), a hybrid decision system and lexical word classification system. Two types of feature extraction techniques have been used in the system, namely statistical and geometrical. Experiments show that the statistical feature is reliable, accessible and offers results that are more accurate. The CRS in this system was implemented using two individual classifiers, namely an adaptive multilayer feed-forward back-propagation neural network and support vector machine. The results of this study are very promising and could generalize to the entire Malay lexical dictionary in future work toward scaled-up applications

Particle physics experiments at JLC

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Systematic mechanical evaluation of electrospun gelatin meshes

Electrospinning is a simple and efficient process for producing sub-micron fibres. However, the process has many variables, and their effects on the non-woven mesh of fibres is complex. In particular, the effects on the mechanical properties of the fibre meshes are poorly understood. This paper conducts a parametric study, where the concentration and bloom strength of the gelatin solutions are varied, while all electrospinning process parameters are held constant. The effects on the fibrous meshes are monitored using scanning electron microscopy and mechanical testing under uniaxial tension. Mesh mechanical properties are relatively consistent, despite changes to the solutions, demonstrating the robustness of electrospinning. The gel strength of the solution is shown to have a statistically significant effect on the morphology, stiffness and strength of the meshes, while the fibre diameter has surprisingly little influence on the stiffness of the meshes. This experimental finding is supported by finite element analysis, demonstrating that the stiffness of the meshes is controlled by the volume fraction, rather than fibre diameter. Our results demonstrate the importance of understanding how electrospinning parameters influence the pore size of the meshes, as controlling fibre diameter alone is insufficient for consistent mechanical properties.This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) via the Doctoral Training Award, Department of Engineering, University of Cambridge, grant number 1354760

The complexities of electronic services implementation and institutionalisation in the public sector

This is the post-print version of the final paper published in Information & Management. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2013 Elsevier B.V.Electronic service implementation (ESI) in the public sector attempts to improve efficiency, effectiveness, and transparency of governmental departments. Despite having provided the necessary infrastructure and investment, many governments have struggled to realise such aims due to the various forces that challenge implementation and institutionalisation. Using institutional theory as a lens, we explored the forces influencing the implementation and institutionalisation of ESI in the public sector. While our results reinforced previous research in IT implementation and organisational transformation, they showed that the dynamic nature of technology poses unanticipated pressures, and that these can impede the implementation and institutionalisation process

Racial/Ethnic Disparities and Determinants of Sufficient Physical Activity Levels

Introduction. It is important to identify racial/ethnic groups that may be less likely to achieve sufficient physical activity levels, and to address barriers to meeting physical activity requirements. Methods. Cross-sectional data from the 2006-2015 National Health Interview Survey (NHIS) was used to compare self-reported sufficient physical activity among different racial/ethnic groups: non-Hispanic (NH) Whites, NH Blacks, NH Asians, and Hispanics. Sufficient physical activity was defined as ≥150 minutes per week of moderate-intensity physical activity, ≥75 minutes per week of vigorous-intensity physical activity, or ≥150 minutes per week of moderate and vigorous physical activity. Results. The study sample consisted of 296,802 individuals, mean age ± standard error age 46.4 ± 0.10 years, 52% women, 70% NH White, 12% NH Black, 5% NH Asian, 14% Hispanic. The prevalence of sufficient physical activity in the overall population was 46%, while it was 48% among NH Whites, 39% among NH Blacks, 45% among NH Asians, and 40% among Hispanics. In multivariable-adjusted models (odds ratio; 95% confidence interval), NH Blacks (0.79; 0.64,0.97), NH Asians (0.72; 0.62,0.85) and Hispanics (0.71; 0.61,0.82) were significantly less likely to engage in sufficient physical activity compared with NH Whites. Older age, women, and low income were inversely associated with sufficient physical activity, while a college education or higher was directly associated with it. Conclusions. NH Black, NH Asian, and Hispanic adults are less likely to engage in sufficient physical activity levels compared with NH Whites. It is important to address barriers to meeting physical activity thresholds to help achieve optimal cardiovascular health

Effectiveness of an antifungal stewardship programme at a London teaching hospital 2010–16

Background The need for antifungal stewardship is gaining recognition with increasing incidence of invasive fungal infection (IFI) and antifungal resistance alongside the high cost of antifungal drugs. Following an audit showing suboptimal practice we initiated an antifungal stewardship programme and prospectively evaluated its impact on clinical and financial outcomes. Patients and methods From October 2010 to September 2016, adult inpatients receiving amphotericin B, echinocandins, intravenous fluconazole, flucytosine or voriconazole were reviewed weekly by an infectious diseases consultant and antimicrobial pharmacist. Demographics, diagnosis by European Organization for Research and Treatment of Cancer (EORTC) criteria, drug, indication, advice, acceptance and in-hospital mortality were recorded. Antifungal consumption and expenditure, and candidaemia species and susceptibility data were extracted from pharmacy and microbiology databases. Results A total of 432 patients were reviewed, most commonly receiving AmBisome® (35%) or intravenous fluconazole (29%). Empirical treatment was often unnecessary, with 82% having no evidence of IFI. Advice was given in 64% of reviews (most commonly de-escalating or stopping treatment) and was followed in 84%. Annual antifungal expenditure initially reduced by 30% (£0.98 million to £0.73 million), then increased to 20% above baseline over a 5 year period; this was a significantly lower rise compared with national figures, which showed a doubling of expenditure over the same period. Inpatient mortality, Candida species distribution and rates of resistance were not adversely affected by the intervention. Conclusions Provision of specialist input to optimize antifungal prescribing resulted in significant cost savings without compromising on microbiological or clinical outcomes. Our model is readily implementable by hospitals with high numbers of at-risk patients and antifungal expenditure

Clinical Relevance of Nontuberculous Mycobacteria, Oman

Little is known about the clinical relevance of nontuberculous mycobacteria (NTM) in the Arabian Peninsula. We assessed the prevalence and studied a random sample of isolates at a reference laboratory in Muscat, Oman. NTM cause disease in this region, and their prevalence has increased