454 research outputs found

    Two-peaked and flat-top perfect bright solitons in epsilon-near-zero nonlinear metamaterials: novel Kerr self-trapping mechanisms

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    We analytically investigate transverse magnetic (TM) spatial bright solitons, as exact solutions of Maxwell's equations, propagating through nonlinear metamaterials whose linear dielectric permittivity is very close to zero and whose effective nonlinear Kerr parameters can be tailored to achieve values not available in standard materials. Exploiting the fact that, in the considered medium, linear and nonlinear polarization can be comparable at feasible and realistic optical intensities, we identify two novel self-trapping mechanisms able to support two-peaked and flat-top solitons, respectively. Specifically, these two novel mechanisms are based on the occurrence of critical points at which the effective nonlinear permittivity vanishes, the two mechanisms differing in the way the compensation between linear and nonlinear polarization is achieved through the non-standard values of the nonlinear parameters.Comment: 7 pages, 4 figure

    Extreme nonlinear electrodynamics in metamaterials with very small linear dielectric permittivity

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    We consider a sub-wavelength periodic layered medium whose slabs are filled by arbitrary linear metamaterials and standard nonlinear Kerr media and we show that the homogenized medium behaves as a Kerr medium whose parameters can assume values not available in standard materials. Exploiting such a parameter availability, we focus on the situation where the linear relative dielectric permittivity is very small thus allowing the observation of the extreme nonlinear regime where the nonlinear polarization is comparable with or even greater than the linear part of the overall dielectric response. The behavior of the electromagnetic field in the extreme nonlinear regime is very peculiar and characterized by novel features as, for example, the transverse power flow reversing. In order to probe the novel regime, we consider a class of fields (transverse magnetic nonlinear guided waves) admitting full analytical description and we show that these waves are allowed to propagate even in media with ϔ0\epsilon0 since the nonlinear polarization produces a positive overall effective permittivity. The considered nonlinear waves exhibit, in addition to the mentioned features, a number of interesting properties like hyper-focusing induced by the phase difference between the field components.Comment: 12 pages, 7 figure

    Integrating Information Technology and Stem Learning Models in Industrial 4.0 Revolution

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    At present the world is entering the era of industrial revolution 4.0 which is closely related to information technology on the basis of human life (Kemenristekdikti, 2018a). With these changes, of course the world of education must also immediately respond to these changes. The steps that can be taken is by integrating information technology with innovative learning models. As a teacher in the Indonesian era 4.0 gave birth to a term known as Teacher 4.0 Challenges & Requirements. To become a 4.0 teacher must have 3 components, namely: 1) Human - Based & Didactical Challengee; 2) Organizational Challengee and 3) Technological Challengee. (Abdelrazeq, 2016). To support these competencies, one of the learning models that can be used is the STEM-based learning model. STEM Education is a combination of areas of Science, Technology, Engineering, and Mathematics (STEM) (Duran, et al., 2016). This paper aims to: 1) explain the perception of information technology and STEM learning for prospective economic teachers. 2) describes the efforts to integrate Information Technology and STEM-based Learning Models in the face of the Age of Industrial Revolution 4.0. Keywords: Industrial Revolution Era 4.0, Information Technology, and Innovative Learning Models, STEM, Teacher Competencies 4.0

    Management and efficacy of intensified insulin therapy starting in outpatients

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    Diabetic patients under multiple injection insulin therapy (i.e., intensified insulin therapy, IIT) usually start this treatment during hospitalization. We report here on the logistics, efficacy, and safety of IIT, started in outpatients. Over 8 months, 52 type I and type II diabetics were followed up whose insulin regimens consecutively had been changed from conventional therapy to IIT. Two different IIT strategies were compared: free mixtures of regular and intermediate (12 hrs)-acting insulin versus the basal and prandial insulin treatment with preprandial injections of regular insulin, and ultralente (24 hrs-acting) or intermediate insulin for the basal demand. After 8 months HbA1 levels had decreased from 10.6%±2.4% to 8.0%±1.3% (means±SD). There was no difference between the two regimens with respect to metabolic control; but type II patients maintained the lowered HbA1 levels better than type I patients. Only two patients were hospitalized during the follow-up time because of severe hypoglycemia. An increase of body weight due to the diet liberalization during IIT became a problem in one-third of the patients. Our results suggest that outpatient initiation of IIT is safe and efficacious with respect to near-normoglycemic control. Weight control may become a problem in IIT patients

    All-optical active plasmonic devices with memory and power switching functionalities based on epsilon-near-zero nonlinear metamaterials

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    All-optical active plasmonic devices are of fundamental importance for designing efficient nanophotonic circuits. We theoretically propose and numerically investigate an active plasmonic device made up of a nonlinear epsilon-near-zero metamaterial slab of thickness smaller than 100 nanometers lying on a linear epsilon-near-zero metamaterial substrate. We predict that, in free-space coupling configuration, the device, operating at low-intensity, would display plasmon mediated hysteresis behavior since the phase difference between the reflected and the incident optical waves turns out to be multi-valued and dependent on the history of the excitation process. Such an hysteresis behavior would allow to regard the proposed device as a compact memory unit whose state is accessible by measuring either the mentioned phase difference or the power, which is multi-valued as well, carried by the nonlinear plasmon wave. Since multiple plasmon powers comprise both positive and negative values, the device would also operate as a switch of the plasmon power direction at each jump along an hysteresis loop.Comment: 9 pages, 4 figure

    Use of Genuine Sources of Ergot Resistance in Species of the \u3ci\u3edilatata\u3c/i\u3e Group of \u3ci\u3ePaspalum\u3c/i\u3e

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    Paspalum dilatatum Poir. (dallisgrass) is an excellent C4 forage for summer production, highly productive with a wide distribution within warm-temperate regions. P. dilatatum is native to South America with special relevance for milk and meat production since its forage quality is superior to that of other C4 forage grasses and it shows tolerance to frost and water stress. In situations of temperate and warm temperate climate, the presence of these species plays a key role in the ecological stability of the system due to the complementarity of the growth cycles between winter and summer grasses. Claviceps paspali (ergot) is a fungus that mainly parasitizes Paspalum spp., generating a structure called sclerotia, in which indole-diterpenoid alkaloids are isolated. Despite the excellent forage characteristics of Paspalum species, there is a need for the generation of varieties able to overcome two major limitations that were identified early on in this species, such as ergot susceptibility and seed production. With this objective, selected genotypes were crossed between apomictic and sexual species of different ploidy using P. malacophyllum as a source of immunity. Immunity to ergot has been evaluated in the field for two years in different representative regions of Uruguay and the accessions that did not get sick were selected as pollen donors. Crosses made with P. flavescens showed a germination percentage ranging between 1.7 and 7.09, while in P. dilatatum var. ChirĂș the range was reduced between 0.99 and 1.25 according to the employed parents. The hybrid nature of the progeny is being verified by microsatellites and functional markers associated with immunity and DNA content estimated by flow cytometry. This work aims to generate the basis to transfer immunity from P. malacophyllum in selected genotypes of Paspalum species predominant in Pampa biome and to improve seed production

    The Richardson's Law in Large-Eddy Simulations of Boundary Layer flows

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    Relative dispersion in a neutrally stratified planetary boundary layer (PBL) is investigated by means of Large-Eddy Simulations (LES). Despite the small extension of the inertial range of scales in the simulated PBL, our Lagrangian statistics turns out to be compatible with the Richardson t3t^3 law for the average of square particle separation. This emerges from the application of nonstandard methods of analysis through which a precise measure of the Richardson constant was also possible. Its values is estimated as C2∌0.5C_2\sim 0.5 in close agreement with recent experiments and three-dimensional direct numerical simulations.Comment: 15 LaTex pages, 4 PS figure

    Determinants of barley grain yield in drought-prone Mediterranean environments

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    The determinants of barley grain yield in drought-prone Mediterranean environments have been studied in the Nure x Tremois (NT) population. A large set of yield and other morpho-physiological data were recorded in 118 doubled haploid (DH) lines of the population, in multi-environment field trials (18 site-year combination). Agrometeorological variables have been recorded and calculated at each site too. Four main periods of barley development were considered, vegetative, reproductive early and late grain filling phases, to dissect the effect on yield traits of the growth phases. Relationships between agrometeorological variables, grain yield (GY) and its main components (GN and GW) were also investigated by correlation. Results firstly gave a clear indication of the involvement of water consumption in determining GY and GW (r2=0.616, P=0.007 and r2=0.703, P=0.005, respectively) calculated from sowing to the early grain filling period, while GN showed its highest correlation with the total photothermal quotient (PQ) calculated for the same period (r2=0.646, P=0.013). With the only exception of total PQ calculated during the vegetative period, all significant correlations with GY were associated to water-dependent agrometeorological parameters. As a second result, the NT segregating population allowed us to weight the amount of interaction due to genotypes over environments or to environments in relation to genotypes by a GGE analysis; 47.67% of G+GE sum of squares was explained by the first two principal components. Then, the introduction of genomic information at major barley genes regulating the length of growth cycle allowed us to explain patterns of adaptation of different groups of NT lines according to the variants (alleles) harbored at venalization (Vrn-H1) in combination with earliness (Eam6) genes. The superiority of the lines carrying the Nure allele at Eam6 was confirmed by factorial ANOVA testing the four possible haplotypes obtained combining alternative alleles at Eam6 and Vrn-H1. Maximum yield potential and differentials among the NT genotypes was finally explored through Finlay-Wilkinson model to interpret grain yield of NT genotypes together with yield adaptability (Ya), as the regression coefficient bi; Ya ranged from 0.71 for NT77 to 1.20 for NT19. Lines simply harboring the Nure variants at the two genes behaved as highest yielding (3.04 t ha\u20131), and showed the highest yield adaptability (bi=1.05). The present study constitutes a starting point towards the introduction of genomic variables in agronomic models for barley grain yield in Mediterranean environments
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