3,493 research outputs found

    Anisotropy and nonlinearity in superlattices

    Get PDF
    This paper uses analytical expressions for the nonlinear optical absorption of superlattices by treating them as anisotropic media. The controllable system shows that the nonlinearities increase with anisotropy suggesting that strongly anisotropic materials such as those used for solar cells may also be useful for nonlinear optical applications

    Simulations of mid infrared emission of InAsN semiconductors

    Get PDF
    This paper delivers an approximation to the complex many body problem of luminescence in semiconductors to the case of mid infrared luminescence of dilute nitrides. The results are compared with recent experimental data for InAsN semiconductors

    Photon-number-resolving segmented avalanche-photodiode detectors

    Full text link
    We investigate the feasibility and performance of photon-number-resolved photodetection employing avalanche photodiodes (APDs) with low dark counts. The main idea is to split n photons over m modes such that every mode has no more than one photon, which is detected alongside propagation by an APD. We characterize performance by evaluating the purities of positive-operator-valued measurements (POVMs), in terms of APD number and photon loss.Comment: 5 pages, 7 figures, submitted for publicatio

    Percutaneous Occlusion of Vascular Malformations in Pediatric and Adult Patients: 20-Year Experience of a Single Center

    Get PDF
    OBJECTIVE: A case series on different vascular malformations (VM) treated with percutaneous occlusion in children and adults is presented. BACKGROUND: Percutaneous occlusion is usually the preferred treatment method for VM. Previous series have mostly focused on single types of devices and/or VM. METHODS: Retrospective analysis of all patients who underwent percutaneous occlusion of VM in a single center, from 1995 to 2014, excluding patent ductus arteriosus. Clinical and angiographic data, procedural details, implanted devices, and complications were assessed. Procedural success was defined as effective device deployment with none or minimal residual flow. Predictors of procedural failure and complications were determined by multivariate analysis. RESULTS: A total of 123 VM were intervened in 47 patients with median age of 12 years (25 days-76 years). The VM included 55 pulmonary arteriovenous fistulae, 39 aortopulmonary collaterals, 10 systemic venovenous collaterals, 8 peripheral arteriovenous fistulae, 5 Blalock-Taussig shunts, 4 coronary fistulae, and 2 Fontan fenestrations. The 143 devices used included 80 vascular plugs, 38 coils, 22 duct occluders, and 3 foramen ovale or atrial septal defect occluders. Median vessel size was 4.5 (2.0-16.0) mm and device/vessel size ratio was 1.4 (1.1-2.0). Successful occlusion was achieved in 118 (95.9%) VM, including three reinterventions. Four (3.3%) clinically relevant complications occurred, without permanent sequelae. Lower body weight was independently associated with procedural failure and complications. CONCLUSION: To our knowledge, this is the largest series on different VM occluded percutaneously in children and adults, excluding patent ductus arteriosus. Percutaneous occlusion was effective and safe, using different devices.info:eu-repo/semantics/publishedVersio

    Thoracic Duct Decompression for Protein-Losing Enteropathy in Failing Fontan Circulation

    Get PDF
    An infrequent but devastating late complication of Fontan circulation is protein-losing enteropathy (PLE), which results from unbalanced lymphatic homeostasis. Surgical decompression of the thoracic duct by redirecting its drainage to the pulmonary venous atrium has been introduced recently as a possible treatment. This report describes a single-institution experience with this innovative procedure in 2 patients with failing Fontan circulation with PLE refractory to optimized medical therapy

    Mode I fracture characterization of human bone using the DCB test

    Get PDF
    Purpose – Fracture characterization of human cortical bone under pure mode I loading was performed in this work. The purpose of this paper is to validate the proposed test and procedure concerning fracture characterization of human cortical bone under pure mode I loading. Design/methodology/approach – A miniaturized version of the double cantilever beam (DCB) test was used for the experimental tests. A data reduction scheme based on crack equivalent concept and Timoshenko beam theory is proposed to overcome difficulties inherent to crack length monitoring during the test. The application of the method propitiates an easy determination of the Resistance-curves (R-curves) that allow to define the fracture energy under mode I loading from the plateau region. The average value of fracture energy was subsequently used in a numerical analysis with element method involving cohesive zone modelling. Findings – The excellent agreement obtained reveals that the proposed test and associated methodology is quite effective concerning fracture characterization of human cortical bone under pure mode I loading. Originality/value – A miniaturized version of traditional DCB test was proposed for cortical human bone fracture characterization under mode I loading owing to size restrictions imposed by human femur. In fact, DCB specimen propitiates a longer length for self-similar crack propagation without undertaking spurious effects. As a consequence, a R-curve was obtained allowing an adequate characterization of cortical bone fracture under mode I loading

    Sustainability assessment of high voltage transmission lines

    Get PDF
    This work aims to contribute to the proposal of a multi-criteria based methodology for sustainability evaluation of impacts from high voltage transmission lines integrating indicators reflecting environmental and socio-economic criteria. The proposed methodology was applied to a transmission grid project in Manaus/Amazonas, Brazil, evaluating its sustainability. From the analysis, it can be observed that the implementation of the project tends to have a significant impact during the construction phase. The most important indexes come from the environmental dimension resulting from a proximity to environmental protected areas and reduction of vegetation both during implementation and operation phases, which is particularly important for the case of Amazonia forest. As for the socio-economic index, this reflects an optimistic expectation of the population towards the arrival of electricity to communities that can lead to the creation of more jobs and improvement of cities infrastructures along with the low expected impact on local protected communities, given the previous studies addressing these concerns during the design phase. Based on the results achieved, avenues for future research are proposed.This work is financed by the ERDF – European Regional Development Fund through the Oper ational Programme for Competitiveness and Internationalisation COMPETE 2020 Programme, and by National Funds through the Portuguese funding agency, FCT Fundação para a Ciência e a Tecnologia, within project SAICTPAC/0004/2015-POCI/01/0145/FEDER/016434.as well as by the ALGORITMI research Centre POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013

    In vivo Skin Irritation Potential of a Castanea sativa (Chestnut) Leaf Extract, a Putative Natural Antioxidant for Topical Application

    Get PDF
    Topical application of natural antioxidants has proven to be effective in protecting the skin against ultraviolet-mediated oxidative damage and provides a straightforward way to strengthen the endogenous protection system. However, natural products can provoke skin adverse effects, such as allergic and irritant contact dermatitis. Skin irritation potential of Castanea sativa leaf ethanol:water (7:3) extract was investigated by performing an in vivo patch test in 20 volunteers. Before performing the irritation test, the selection of the solvent and extraction method was guided by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging test and polyphenols extraction (measured by the Folin Ciocalteu assay). Iron-chelating activity and the phenolic composition (high performance liquid chromatography/diode array detection) were evaluated for the extract obtained under optimized conditions. The extraction method adopted consisted in 5 short extractions (10 min.) with ethanol:water (7:3), performed at 40 degrees. The IC(50) found for the iron chelation and DPPH scavenging assays were 132.94 +/- 9.72 and 12.58 +/- 0.54 microg/ml (mean +/- S.E.M.), respectively. The total phenolic content was found to be 283.8 +/- 8.74 mg GAE/g extract (mean +/- S.E.M.). Five phenolic compounds were identified in the extract, namely, chlorogenic acid, ellagic acid, rutin, isoquercitrin and hyperoside. The patch test carried out showed that, with respect to irritant effects, this extract can be regarded as safe for topical application
    • …
    corecore