Growth control of GaAs nanowires using pulsed laser deposition with arsenic over pressure

Using pulsed laser ablation with arsenic over pressure, the growth conditions for GaAs nanowires have been systematically investigated and optimized. Arsenic over pressure with As$_2$ molecules was introduced to the system by thermal decomposition of polycrystalline GaAs to control the stoichiometry and shape of the nanowires during growth. GaAs nanowires exhibit a variety of geometries under varying arsenic over pressure, which can be understood by different growth processes via vapor-liquid-solid mechanism. Single-crystal GaAs nanowires with uniform diameter, lengths over 20 $\mu$m, and thin surface oxide layer were obtained and can potentially be used for further electronic characterization

GlobVolcano Project Overview

The GlobVolcano project is part of the ESA DUE programme. The project aims at demonstrating EO-based services to support the Volcanological Observatories and other mandate users (e.g. Civil Protection authorities, scientific communities of volcanoes) in their monitoring activities. During the project a worldwide selection of user organizations will cooperate with the GlobVolcano team in order to harmonize user’s requirements and to evaluate the EO-based services . The “Osservatorio Vesuviano” of Naples (INGV-Italy) coordinates the communications between the project and the User Community. IPGP of Paris is responsible for the scientific coordination and the validation activities. The project activities are split in two phases. During the first phase (completed in June 2008) the service infrastructure and interface to the users have been developed. Prototype EO-based information products have been generated and validated. Service provision on pre-operational basis will take place during the second phase

Cost-effective intervention thresholds against osteoporotic fractures based on FRAX® in Switzerland

Summary: FRAX-based cost-effective intervention thresholds in the Swiss setting were determined. Assuming a willingness to pay at 2× Gross Domestic Product per capita, an intervention aimed at reducing fracture risk in women and men with a 10-year probability for a major osteoporotic fracture at or above 15% is cost-effective. Introduction: The fracture risk assessment algorithm FRAX® has been recently calibrated for Switzerland. The aim of the present analysis was to determine FRAX-based fracture probabilities at which intervention becomes cost-effective. Methods: A previously developed and validated state transition Markov cohort model was populated with Swiss epidemiological and cost input parameters. Cost-effective FRAX-based intervention thresholds (cost-effectiveness approach) and the cost-effectiveness of intervention with alendronate (original molecule) in subjects with a FRAX-based fracture risk equivalent to that of a woman with a prior fragility fracture and no other risk factor (translational approach) were calculated based on the Swiss FRAX model and assuming a willingness to pay of 2 times Gross Domestic Product per capita for one Quality-adjusted Life-Year. Results: In Swiss women and men aged 50years and older, drug intervention aimed at decreasing fracture risk was cost-effective with a 10-year probability for a major osteoporotic fracture at or above 13.8% (range 10.8% to 15.0%) and 15.1% (range 9.9% to 19.9%), respectively. Age-dependent variations around these mean values were modest. Using the translational approach, treatment was cost-effective or cost-saving after the age 60years in women and 55 in men who had previously sustained a fragility fracture. Using the latter approach leads to considerable underuse of the current potential for cost-effective interventions against fractures. Conclusions: Using a FRAX-based intervention threshold of 15% for both women and men should permit cost-effective access to therapy to patients at high fracture probability based on clinical risk factors and thereby contribute to further reduce the growing burden of osteoporotic fractures in Switzerlan

Tunable few electron quantum dots in InAs nanowires

Quantum dots realized in InAs are versatile systems to study the effect of spin-orbit interaction on the spin coherence, as well as the possibility to manipulate single spins using an electric field. We present transport measurements on quantum dots realized in InAs nanowires. Lithographically defined top-gates are used to locally deplete the nanowire and to form tunneling barriers. By using three gates, we can form either single quantum dots, or two quantum dots in series along the nanowire. Measurements of the stability diagrams for both cases show that this method is suitable for producing high quality quantum dots in InAs.Comment: 8 pages, 4 figure

Potential of a cyclone prototype spacer to improve in vitro dry powder delivery

Copyright The Author(s) 2013. This article is published with open access at Springerlink.com. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are creditedPurpose: Low inspiratory force in patients with lung disease is associated with poor deagglomeration and high throat deposition when using dry powder inhalers (DPIs). The potential of two reverse flow cyclone prototypes as spacers for commercial carrierbased DPIs was investigated. Methods: Cyclohaler®, Accuhaler® and Easyhaler® were tested with and without the spacers between 30-60 Lmin-1. Deposition of particles in the next generation impactor and within the devices was determined by high performance liquid chromatography. Results: Reduced induction port deposition of the emitted particles from the cyclones was observed due to the high retention of the drug within the spacers (e.g. salbutamol sulphate (SS): 67.89 ± 6.51 % at 30 Lmin-1 in Cheng 1). Fine particle fractions of aerosol as emitted from the cyclones were substantially higher than the DPIs alone. Moreover, the aerodynamic diameters of particles emitted from the cyclones were halved compared to the DPIs alone (e.g. SS from the Cyclohaler® at 4 kPa: 1.08 ± 0.05 μm vs. 3.00 ± 0.12 μm, with and without Cheng 2, respectively) and unaltered with increased flow rates. Conclusion: This work has shown the potential of employing a cyclone spacer for commercial carrier-based DPIs to improve inhaled drug delivery.Peer reviewe

Twinning superlattices in indium phosphide nanowires

Here, we show that we control the crystal structure of indium phosphide (InP) nanowires by impurity dopants. We have found that zinc decreases the activation barrier for 2D nucleation growth of zinc-blende InP and therefore promotes the InP nanowires to crystallise in the zinc blende, instead of the commonly found wurtzite crystal structure. More importantly, we demonstrate that we can, by controlling the crystal structure, induce twinning superlattices with long-range order in InP nanowires. We can tune the spacing of the superlattices by the wire diameter and the zinc concentration and present a model based on the cross-sectional shape of the zinc-blende InP nanowires to quantitatively explain the formation of the periodic twinning.Comment: 18 pages, 4 figure

Fabular: regression formulas as probabilistic programming

Regression formulas are a domain-specific language adopted by several R packages for describing an important and useful class of statistical models: hierarchical linear regressions. Formulas are succinct, expressive, and clearly popular, so are they a useful addition to probabilistic programming languages? And what do they mean? We propose a core calculus of hierarchical linear regression, in which regression coefficients are themselves defined by nested regressions (unlike in R). We explain how our calculus captures the essence of the formula DSL found in R. We describe the design and implementation of Fabular, a version of the Tabular schema-driven probabilistic programming language, enriched with formulas based on our regression calculus. To the best of our knowledge, this is the first formal description of the core ideas of R's formula notation, the first development of a calculus of regression formulas, and the first demonstration of the benefits of composing regression formulas and latent variables in a probabilistic programming language.Adam Ścibior received travel support from the DARPA PPAML programme. Marcin Szymczak was supported by Microsoft Research through its PhD Scholarship Programme.This is the author accepted manuscript. The final version is available from the Association of Computer Machinery via http://dx.doi.org/10.1145/2837614.283765

MONITORING THE CAMPI FLEGREI CALDERA BY EXPLOITING SAR AND GEODETICAL DATA: RECENT RESULTS AND FUTURE APPLICATIONS

Geodetical monitoring of the Campi Flegrei caldera (Naples, Italy), has been historically carried out by ground networks giving an information related only to a certain number of measuring points; this limitation can be greatly relieved by exploiting the space-borne DInSAR which allows to extract the geodetic information on wide areas, with a good time coverage in comparison with the mean repetition time of the campaign measurements. In this work we will show recent results on Campi Flegrei, obtained by using all the ENVISAT ASAR available data from both ascending and descending orbits. The processed data revealed that the uplift phase of Campi Flegrei, which became very clear in summer 2005 with an average velocity of about 2.8 mm/year, has definitely reduced the uplift velocity since spring 2007. This conclusion is consistent with independent deformation measurements carried out by the Vesuvius Observatory (INGV-OV). Differences, in terms of limits and potentialities of DInSAR with respect to classical geodetic techniques and vice-versa and the way they can be compared/integrated, is still a very interesting matter of debate suggesting, as an optimal solution for monitoring purposes in active volcanic areas, the integration of all the available techniques.UnpublishedFrascati1.10. TTC - Telerilevamentoope