927 research outputs found

    Super-resolution provided by the arbitrarily strong superlinearity of the blackbody radiation

    Get PDF
    Blackbody radiation is a fundamental phenomenon in nature, and its explanation by Planck marks a cornerstone in the history of Physics. In this theoretical work, we show that the spectral radiance given by Planck's law is strongly superlinear with temperature, with an arbitrarily large local exponent for decreasing wavelengths. From that scaling analysis, we propose a new concept of super-resolved detection and imaging: if a focused beam of energy is scanned over an object that absorbs and linearly converts that energy into heat, a highly nonlinear thermal radiation response is generated, and its point spread function can be made arbitrarily smaller than the excitation beam focus. Based on a few practical scenarios, we propose to extend the notion of super-resolution beyond its current niche in microscopy to various kinds of excitation beams, a wide range of spatial scales, and a broader diversity of target objects

    Granular size segregation in underwater sand ripples

    Full text link
    We report an experimental study of a binary sand bed under an oscillating water flow. The formation and evolution of ripples is observed. The appearance of a granular segregation is shown to strongly depend on the sand bed preparation. The initial wavelength of the mixture is measured. In the final steady state, a segregation in volume is observed instead of a segregation at the surface as reported before. The correlation between this phenomenon and the fluid flow is emphasised. Finally, different ``exotic'' patterns and their geophysical implications are presented.Comment: 8 page

    Thermal effects on electron-phonon interaction in silicon nanostructures

    Full text link
    Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.Comment: 9 Pages, 3 Figures and 1 Tabl

    a simulative model of a 5g telco operator network

    Get PDF
    Abstract In the near future, an important milestone for the evolution of wireless technologies will be the deployment of 5G network, having the target of supporting very huge data rate generated by a very high number of devices. One of the main technological enablers in this evolution is the joint SDN/NFV paradigm, defined in the last years to support the softwarization process of the Telco Operator networks. Given the very hard quality of experience (QoE) and quality of service (QoS) requirements in some application scenarios, mainly in terms of end-to-end delay, a challenging activity is to realize tools that can support network architects in performance evaluation and network design. With this in mind, this paper proposes a simulative tool for 5G networks, which is able to capture delay statistics due to both CPU load and transmission link congestions in NFVI-PoP nodes. The model is then applied to a case study to demonstrate how it can be applied for performance evaluation

    Precision measurements of Linear Scattering Density using Muon Tomography

    Full text link
    We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.Comment: 16 pages, 4 figure

    Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating

    Full text link
    We model the photoelectric emission from and charging of interstellar dust and obtain photoelectric gas heating efficiencies as a function of grain size and the relevant ambient conditions. Using realistic grain size distributions, we evaluate the net gas heating rate for various interstellar environments, and find less heating for dense regions characterized by R_V=5.5 than for diffuse regions with R_V=3.1. We provide fitting functions which reproduce our numerical results for photoelectric heating and recombination cooling for a wide range of interstellar conditions. In a separate paper we will examine the implications of these results for the thermal structure of the interstellar medium. Finally, we investigate the potential importance of photoelectric heating in H II regions, including the warm ionized medium. We find that photoelectric heating could be comparable to or exceed heating due to photoionization of H for high ratios of the radiation intensity to the gas density. We also find that photoelectric heating by dust can account for the observed variation of temperature with distance from the galactic midplane in the warm ionized medium.Comment: 50 pages, including 18 figures; corrected title and abstract field

    A NEW SHORT VERSION OF INTERNET GAMING DISORDER-20: AN EXPLORATORY STRUCTURAL EQUATION MODELING

    Get PDF
    Objective: The purpose of this paper was to contribute to the psychometric properties and dimensionality of the IGD-20. Method: An online survey was completed by 392 Italian online gamers (Mage = 29.2, SD = 11.3; 45.2% males). A battery of self-report questionnaires was administered to assess internet gaming disorder, internet addiction, loneliness, anxiety, depression, stress, social-interaction anxiety, self-esteem, and perceived social support. To test the factor structure of IGD-20, both traditional (i.e., EFA and CFA) and innovative (i.e., ESEM) techniques were applied. Convergent, concurrent, discriminant, and criterion-related validity were evaluated. Results: Our study revealed the outperforming 3-factor ESEM model (χ2=39.951, p = 0.0021; RMSEA = 0.056, 90% C.I. [0.032 - 0.079]; CFI = 0.986; TLI = 0.965; and SRMR = 0.017; ω = .76, .77, and .79, respectively) as a new short version (IGD- 10SV) for the IGD-20. The validity of the IGD-10SV was supported by significant associations with theoretically related measures. Conclusions: The current findings support the adoption of the analytic ESEM approach for complex multidimensional measures and the use of the IGD-10SV for the assessment of internet gaming disorder

    Napoleone Colajanni La Grande guerra e la Rivoluzione russa

    Get PDF
    In this essay the author studies the influence of Russian revolutionary events on the democratic interventionist Napoleone Colajanni's institutional and political activity, during and after WWI. From the analysis of his written work, published in many magazines, emerges Colajanni's enthusiasm for the February Revolution and his condemnation of the October Revolution. He considered the latter anti-democratic and authoritarian, because of its application of Bolshevik ideology, and also that it had influenced Italian reformism to adopt maximalist positions. From this derived his efforts to conjugate socialism and democracy, even if before his death Colajanni showed some appreciation for the first steps of Fascism
    corecore