130,776 research outputs found
Slow light with interleaved p-n junction to enhance performance of integrated Mach-Zehnder silicon modulators
No full textSlow light is a very important concept in nanophotonics, especially in the context of photonic crystals. In this work, we apply our previous design of band-edge slow light in silicon waveguide gratings [M. Passoni et al, Opt. Express 26, 8470 (2018)] to Mach-Zehnder modulators based on the plasma dispersion effect. The key idea is to employ an interleaved p-n junction with the same periodicity as the grating, in order to achieve optimal matching between the electromagnetic field profile and the depletion regions of the p-n junction. The resulting modulation efficiency is strongly improved as compared to common modulators based on normal rib waveguides, even in a bandwidth of 20–30 nm near the band edge, while the total insertion loss due to free carriers is not increased. The present concept is promising in view of realizing slow-light modulators for silicon photonics with reduced energy dissipation
Target normal sheath acceleration analytical modeling, comparative study and developments
No full textUltra-intense laser interaction with solid targets appears to be an extremely promising technique to accelerate ions up to several MeV, producing beams that exhibit interesting properties for many foreseen applications. Nowadays, most of all the published experimental results can be theoretically
explained in the framework of the target normal sheath acceleration (TNSA) mechanism proposed by Wilks et al. [Phys. Plasmas 8(2), 542 (2001)]. As an alternative to numerical simulation various analytical or semi-analytical TNSA models have been published in the latest years, each of them trying to provide predictions for some of the ion beam features, given the initial laser and target parameters. However, the problem of developing a reliable model for the TNSA process is still open, which is why the purpose of this work is to enlighten the present situation of TNSA modeling and experimental results, by means of a quantitative comparison between measurements and theoretical predictions of the maximum ion energy. Moreover, in the light of such an analysis, some indications
for the future development of the model proposed by Passoni and Lontano [Phys. Plasmas 13(4), 042102 (2006)] are then presented
Target normal sheath acceleration analytical modeling, comparative study and developments
No full textUltra-intense laser interaction with solid targets appears to be an extremely promising technique to accelerate ions up to several MeV, producing beams that exhibit interesting properties for many foreseen applications. Nowadays, most of all the published experimental results can be theoretically explained in the framework of the target normal sheath acceleration (TNSA) mechanism proposed by Wilks [Phys. Plasmas 8(2), 542 (2001)10.1063/1.1333697]. As an alternative to numerical simulation various analytical or semi-analytical TNSA models have been published in the latest years, each of them trying to provide predictions for some of the ion beam features, given the initial laser and target parameters. However, the problem of developing a reliable model for the TNSA process is still open, which is why the purpose of this work is to enlighten the present situation of TNSA modeling and experimental results, by means of a quantitative comparison between measurements and theoretical predictions of the maximum ion energy. Moreover, in the light of such an analysis, some indications for the future development of the model proposed by Passoni and Lontano [Phys. Plasmas 13(4), 042102 (2006)10.1063/1.2184067] are then presented. © 2012 American Institute of Physics
Superstrong2010: Special issue of Nuclear Instruments and Methods A (vol. 653)
No full textThe special issue ‘‘Superstrong2010’ ’of Nuclear Instruments
and Methods A constitutes the proceedings of the Fourth International
Conference on Superstrong Fields in Plasmas, which took
place in Varenna, Italy,from October 3 to October 9, 2010
Preface to the special issue "Superstrong 2010" of Nuclear Instruments and Methods in Physics Research A.
No full textThis is the preface of the special issue of Nuclear Instruments and Methods A, vol. 653, for which I am Guest Editor
A new large-eddy simulation near-wall treatment
No full textTwo different types of instantaneous wall boundary conditions have been proposed for resolved large scale simulations that extend inside the viscous sublayer. These conditions transfer the physical no-slip and impermeability/permeability information,which can only be rigorously applied to the unfiltered variables,to the filtered variables. The first condition is universal,while the second one specifies the wall stress and relevant distribution and can be used to treat inverse flow problems. The filter scale close to the wall is a function which varies according to its position and thus the problem of the noncommutation of the filter and differentiation operators arises. Used together with the explicit noncommutation procedure by Iovieno and Tordella,these boundary conditions constitute a wall treatment which could improve the use of the large-eddy methodology in relation to aspects that are independent of the modeling of the subgrid scale motion. When applied in the test case of the plane periodic channel,intentionally using the most crude subgrid scale model (Smagorinsky,with no dynamic procedure or wall damping function) to prove its efficacy,the proposed near-wall treatment yielded resolved large-eddy simulations which compare well with both direct numerical simulations and with experimental data. The effects of the Reynolds number on the structure of the flow are retained. Distributions of the noncommutation error on the turbulent solution are also reported
Developments in Target Normal Sheath Acceleration theoretical modeling: Ion cut-off energy dependence on target thickness and transverse size
No full textExperimental Tests on the Benefits of a More Rigorous Model in IMU/GPS System Calibration
No full text
Nutritional challenges during pregnancy
No full textNutrition and lifestyle during pregnancy and preconceptional period represent a major public health challenge, influencing the development of the embryo, fetus, and placenta, with considerable potential to influence not only maternal health but also that of future generations. However, the risk of inadequate maternal nutrition is high both in underdevel-oped and in industrialized countries, where inflammation due to maternal obesi-ty, stress and pollution seems to play a major role in mediating maternal, perinatal and long-term adverse outcomes. These dietary inadequacies are due to complex socio-cultural and economic in-teracting factors and it is to date mandatory to incorporate in clinician’s appoint-ment brief nutrition discussions supported by easy questionnaires and to pro-pose simple and personalized multidisciplinary interventions
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