Electron-phonon interaction in quantum-dot/quantum-well semiconductor heterostructures

Polar optical phonons are studied in the framework of the dielectric continuum approach for a prototypical quantum-dot/quantum-well (QD/QW) heterostructure, including the derivation of the electron-phonon interaction Hamiltonian and a discussion of the effects of this interaction on the electronic energy levels. The particular example of the CdS/HgS QD/QW is addressed and the system is modelled according to the spherical geometry, considering a core sphere of material "1" surrounded by a spherically concentric layer of material "2", while the whole structure is embedded in a host matrix assumed as an infinite dielectric medium. The strength of the electron-LO phonon coupling is discussed in details and the polaronic corrections to both ground state and excited state electron energy levels are calculated. Interesting results concerning the dependence of polaronic corrections with the QD/QW structure size are analyzed.Comment: 8 pages, 5 figure

HBIM FROM A FIRST CENTURY ICONOGRAPHY

Abstract. Protecting and enhancing inherited assets is a duty of every age; ours requires disclosure through the services of the interconnected network, the only one, to date, capable of reaching a wide audience and with it attracting adequate economic resources for the implementation of programs. In keeping with the international definition of "Cultural Heritage", the paper describes the methodology that guided the construction in 3D of the monumental building sculpted in the iconographies between 52 and 62 AD on the marble slab now preserved at the archaeological museum of Perugia. An informative workflow on what has been collected is proposed to then discuss the potential of its uses. The focus lies in particular on the possibility of the model to act as an interoperable collector to compare the reconstructive hypotheses.The final objective looks at the opportunity to create multimedia, multimodal and cross modal collaboration spaces to remedy aspects that, by affecting a wider audience of users, encourage socio-economic policies

On the Use of the Theory of Critical Distances with Mesh Control for Fretting Fatigue Lifetime Assessment

This work analyses the viability of the theory of critical distances (TCD) using mesh control for fretting fatigue lifetime assessment. More than seven hundred sets of simulations were performed by taking seventy different experimental tests reported previously in the literature. The outcome of the present study suggests that the TCD mesh control method can be extended to fretting fatigue problems by the reasonable assumption of setting the right element size proportional to critical distance. In this study, a significant computational time reduction of up to 97% was obtained. Thus, this study provides a simple method to design complex 3D industrial components subjected to fretting fatigue phenomena using finite element analysis efficiently without requiring complex remeshing techniques

Interface optical phonons in spheroidal dots: Raman selection rules

The contribution of interface phonons to the first order Raman scattering in nanocrystals with non spherical geometry is analyzed. Interface optical phonons in the spheroidal geometry are discussed and the corresponding Frohlich-like electron-phonon interaction is reported in the framework of the dielectric continuum approach. It is shown that the interface phonon modes are strongly dependent on the nanocrystal geometry, particularly on the ellipsoid's semi-axis ratio. The new Raman selection rules have revealed that solely interface phonon modes with even angular momentum are allowed to contribute to the first order phonon-assisted scattering of light. On this basis we are able to give an explanation for the observed low frequency shoulders present in the Raman cross-section of several II-VI semiconductor nanostructures.Comment: 8 pages, 2 figure

Management of Operational Parameters and Novel Spinneret Configurations for the Electrohydrodynamic Processing of Functional Polymers

[EN] Functional materials have become key drivers in the development of multiple high-end technologies. Electrohydrodynamic processing (EHDP) is a straightforward method to generate polymer micro- and nanostructures that can be applied to the food, pharmaceutical, environmental, and biomedical areas, among others, since these can yield materials with higher performance. Some of the EHDP's advantages over other polymer processing technologies rely on its high versatility, by which the final assembly can be modified in different ways to combine materials with multiple properties and also in different morphological structures, and the use of room processing conditions, meaning that thermolabile ingredients can be incorporated with minimal activity loss. This review provides the historical background, process basics, and the state-of-the-art of the most recent advances achieved in the EHDP technology dealing with the control of its operational parameters to optimize processability and achieve end-product quality and homogeneity. It also focuses on the newly developed modes of operation and spinneret configurations that can lead to the formation of a wide range of micro- and nanostructures with different functionalities and solve some of its current technical limitations. Finally, it also further highlights the potential applications of the resultant hierarchical functional polymer-based materials obtained by these novel EHDP methods.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and by the I&D&I AgriFood XXI project, operation number NORTE-01-0145-FEDER-000041, co-financed by the European Regional Development Fund (FEDER) under the scope of NORTE 2020 (ProgramaOperacional Regional do Norte 2014/2020). Pedro Silva is the recipient of a fellowship (SFRD/BD/130247/2017) supported by FCT. S. TorresGiner acknowledges Spanish Ministry of Science and Innovation (MICI) for the funding received during his Ramon y Cajal contract (RYC2019027784-I).Silva, PM.; Torres-Giner, S.; Vicente, AA.; Cerqueira, MA. (2022). Management of Operational Parameters and Novel Spinneret Configurations for the Electrohydrodynamic Processing of Functional Polymers. Macromolecular Materials and Engineering. 307(5):1-21. https://doi.org/10.1002/mame.202100858121307

Discrete time analysis of cognitive radio networks with imperfect sensing and saturated source of secondary users, Computer Communications

Sensing is one of the most challenging issues in cognitive radio networks. Selection of sensing parameters raises several tradeoffs between spectral efficiency, energy efficiency and interference caused to primary users (PUs). In this paper we provide representative mathematical models that can be used to analyze sensing strategies under a wide range of conditions. The activity of PUs in a licensed channel is modeled as a sequence of busy and idle periods, which is represented as an alternating Markov phase renewal process. The representation of the secondary users (SUs) behavior is also largely general: the duration of transmissions, sensing periods and the intervals between consecutive sensing periods are modeled by phase type distributions, which constitute a very versatile class of distributions. Expressions for several key performance measures in cognitive radio networks are obtained from the analysis of the model. Most notably, we derive the distribution of the length of an effective white space; the distributions of the waiting times until the SU transmits a given amount of data, through several transmission epochs uninterruptedly; and the goodput when an interrupted SU transmission has to be restarted from the beginning due to the presence of a PU. (C) 2015 Elsevier B.V. All rights reserved.The research of A. S. Alfa was partially supported by the NSERC (Natural Sciences and Engineering Research Council) of Canada under Grant G00315156. Most of the contribution of V. Pla was done while visiting the University of Manitoba. This visit was supported by the Ministerio de Educacion of Spain under Grant PR2011-0055, and by the UPV through the Programa de Apoyo a la Investigacion y Desarrollo (PAID-00-12). The research of the authors from the Universitat Politecnica de Valencia was partially supported by the Ministry of Economy and Competitiveness of Spain under Grant TIN2013-47272-C2-1-R.Alfa, AS.; Pla, V.; Martínez Bauset, J.; Casares Giner, V. (2016). Discrete time analysis of cognitive radio networks with imperfect sensing and saturated source of secondary users, Computer Communications. Computer Communications. 79:53-65. https://doi.org/10.1016/j.comcom.2015.11.012S53657

Initial management of and outcome in patients with pneumococcal bacteremia: a retrospective study at a Swiss university hospital, 2003-2009

Purpose: The aim of this quality control study was to assess the time to initial diagnostic procedures and the time to the first dose of antibiotics in patients with pneumococcal bacteremia, and to investigate whether the timeliness of these interventions influenced outcome. Methods: We retrospectively studied patient characteristics, chronological sequence of diagnostic and therapeutic steps, and the course of disease of all patients with pneumococcal bacteremia at a Swiss university hospital between 2003 and 2009, and we analyzed associations between these factors and the length of hospital stay (LOS) and mortality. Results: A total of 102 episodes of pneumococcal bacteremia in 98 patients were analyzed, of whom 15.7% died during hospitalization. The median time (interquartile range [IQR]) to the first antibiotic dose was 4.0 (2.0-5.9)h, and the median times (IQR]) to blood cultures, chest radiograph, lumbar puncture, and brain computed tomography (CT) scan or magnetic resonance imaging (MRI) were 1.4 (0.5-3.3), 2.5 (1.2-4.2), 4.2 (2.7-7.2), and 2.3 (0.6-6.2)h, respectively. The time to diagnostic procedures and therapy were not associated with LOS or death. Risk factors for death in the univariable analysis were: Charlson comorbidity index [odds ratio [OR] (95% confidence interval) per unit increase, 1.3 (1.1-1.6)], neutropenia [OR 10.1 (2.0-51.0)], human immunodeficiency virus (HIV) infection [OR 3.9 (1.1-13.8)], chronic respiratory disease [OR 4.4 (1.2-16.0)], chronic liver disease [OR 3.2 (1.0-9.7)], smoking [OR 3.8 (1.1-13.5)], injection drug use [OR 9.7 (1.5-63.7)], and antibiotic therapy within 6months before admission [OR 4.0 (1.3-12.5)]. The multivariable analysis revealed age >60years (P=0.048) and alcoholism (P=0.009) as risks for prolonged LOS. Conclusions: The outcome of pneumococcal bacteremia may be more influenced by patient characteristics than by minor differences in the timeliness of initial diagnostic and therapeutic measures within the first several hours after hospital admissio

Evaluation of the performance of three serological tests for diagnosis of Leishmania infantum infection in dogs using latent class analysis

Canine leishmaniasis (CanL) is a disease caused by Leishmania infantum. Serological methods are the most common diagnostic techniques used for the diagnosis of the CanL. The objective of our study was to estimate the sensitivity and specificity of one in-house ELISA kit (ELISA UNIZAR) and three commercially available serological tests (MEGACOR Diagnostik GmbH) including an immunochromatographic rapid test (FASTest LEISH®), an immunofluorescent antibody test (MegaFLUO LEISH®) and an enzyme-linked immunosorbent assay (MegaELISA LEISH®), using latent class models in a Bayesian analysis. Two hundred fifteen serum samples were included. The highest sensitivity was achieved for FASTest LEISH® (99.38%), ELISA UNIZAR (99.37%), MegaFLUO LEISH® (99.36%) followed by MegaELISA LEISH® (98.49%). The best specificity was obtained by FASTest LEISH® (98.43%), followed by ELISA UNIZAR (97.50%), whilst MegaFLUO LEISH® and MegaELISA LEISH® obtained the lower specificity (91.94% and 91.93%, respectively). The results of present study indicate that the immunochromatographic rapid test evaluated FASTest LEISH® show similar levels of sensitivity and specificity to the quantitative commercial tests. Among quantitative serological tests, sensitivity and specificity were similar considering ELISA or IFAT techniques. A leishmaniose canina (Lcan) é uma doença causada pela Leishmania infantum. Os métodos sorológicos são as técnicas diagnósticas mais utilizadas para o diagnóstico da leishmaniose canina. O objetivo do nosso estudo foi estimar a sensibilidade e a especificidade de um kit ELISA interno (ELISA UNIZAR) e de três testes sorológicos disponíveis comercialmente, feitos pelo mesmo fabricante (MEGACOR Diagnostik GmbH), incluindo um teste rápido imunocromatográfico (FASTest LEISH®), um teste de anticorpos imunofluorescentes (Megafluo LEISH®) e um ensaio de imunoabsorção enzimática (Megaelisa LEISH®), utilizando-se modelos de classe latentes numa análise bayesiana. Foram incluídas duzentas e quinze amostras de soro. A maior sensibilidade foi alcançada para Fastest LEISH® (99, 38%), ELISA UNIZAR (99, 37%), Megafluo LEISH® (99, 36%) seguida por Megaelisa LEISH® (98, 49%). A melhor especificidade foi obtida por FASTest LEISH® (98, 43%), seguida por ELISA UNIZAR (97, 50%), enquanto Megafluo LEISH® e Megaelisa LEISH® obtiveram a menor especificidade (91, 94% e 91, 93%, respectivamente). Os resultados do presente estudo indicam que o teste rápido imunocromatográfico, avaliado por FASTest LEISH® mostra níveis similares de sensibilidade e especificidade aos testes comerciais quantitativos incluídos. Entre os testes sorológicos quantitativos, a sensibilidade e a especificidade foram semelhantes, considerando-se as técnicas de ELISA ou IFI