1,198 research outputs found

    Comparative Analysis of File Transfer Performance Between Java and.NET Using a Hybrid Encryption Protocol with AES and RSA

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    The purpose of the research project was to carry out the comparative analysis of the performance of a computer system using a hybrid encryption protocol (symmetric AES and asymmetric RSA) and the mechanism of sockets between the JAVA and.NET platforms, applied to the system of information backups for the Loja Technical Office of the Zonal Coordination 7 of the Identification and Certification of the Civil Registry. To determine the performance between both platforms, the analysis of each indicator obtained from the FURPS Model was done with a sample of 335 files distributed among 200 light, 100 medium and 35 heavy, for which the nonparametric analysis algorithm Mann–Whiney was used, obtaining as a result a significant difference in favor of C # in terms of response time, while for the consumption of resources (RAM and CPU) a significant difference was found in favor of Java.   Keywords: cryptography, AES, RSA, Java, C

    A model for stem cell population dynamics with regulated maturation delay

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    We develop a structured population model for the maturation process of stem cells in the form of a state-dependent delay differential equation. Moreover, results on existence, uniqueness and positivity of solutions as well as conditions of existence for equilibria and representations of these are established. We give biological interpretations for the conditions of existence of equilibria

    Global dynamics of two-compartment models for cell production systems with regulatory mechanisms

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    We present a global stability analysis of two-compartment models of a hierarchical cell production system with a nonlinear regulatory feedback loop. The models describe cell differentiation processes with the stem cell division rate or the self-renewal fraction regulated by the number of mature cells. The two-compartment systems constitute a basic version of the multicompartment models proposed recently by Marciniak-Czochra and collaborators [25] to investigate the dynamics of the hematopoietic system. Using global stability analysis, we compare different regulatory mechanisms. For both models, we show that there exists a unique positive equilibrium that is globally asymptotically stable if and only if the respective reproduction numbers exceed one. The proof is based on constructing Lyapunov functions, which are appropriate to handle the specific nonlinearities of the model. Additionally, we propose a new model to test biological hypothesis on the regulation of the fraction of differentiating cells. We show that such regulatory mechanism is incapable of maintaining homeostasis and leads to unbounded cell growth. Potential biological implications are discussed

    Encapsulation of gold nanostructures and oil-in-water nanocarriers in microgels with biomedical potential

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    Indexación: Scopus.Funding: This research was funded by FONDECYT 1161450, 1150744, 11130494 and 1170929, FONDEQUIP EQM160157, EQM170111, CONICYT-FONDAP 15130011, and CONICYT PhD Scholarship 21141137.Here we report the incorporation of gold nanostructures (nanospheres or nanorods, functionalized with carboxylate-end PEG) and curcumin oil-in-water (O/W) nanoemulsions (CurNem) into alginate microgels using the dripping technique. While gold nanostructures are promising nanomaterials for photothermal therapy applications, CurNem possess important pharmacological activities as reported here. In this sense, we evaluated the effect of CurNem on cell viability of both cancerous and non-cancerous cell lines (AGS and HEK293T, respectively), demonstrating preferential toxicity in cancer cells and safety for the non-cancerous cells. After incorporating gold nanostructures and CurNem together into the microgels, microstructures with diameters of 220 and 540 µm were obtained. When stimulating microgels with a laser, the plasmon effect promoted a significant rise in the temperature of the medium; the temperature increase was higher for those containing gold nanorods (11–12 ◦ C) than nanospheres (1–2 ◦ C). Interestingly, the incorporation of both nanosystems in the microgels maintains the photothermal properties of the gold nanostructures unmodified and retains with high efficiency the curcumin nanocarriers. We conclude that these results will be of interest to design hydrogel formulations with therapeutic applications. © 2018 by the authors.https://www.mdpi.com/1420-3049/23/5/120

    Resonant Magnetic Vortices

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    By using the complex angular momentum method, we provide a semiclassical analysis of electron scattering by a magnetic vortex of Aharonov-Bohm-type. Regge poles of the SS-matrix are associated with surface waves orbiting around the vortex and supported by a magnetic field discontinuity. Rapid variations of sharp characteristic shapes can be observed on scattering cross sections. They correspond to quasibound states which are Breit-Wigner-type resonances associated with surface waves and which can be considered as quantum analogues of acoustic whispering-gallery modes. Such a resonant magnetic vortex could provide a new kind of artificial atom while the semiclassical approach developed here could be profitably extended in various areas of the physics of vortices.Comment: 6 pages, 7 figure

    Nonlinear Aharonov-Bohm scattering by optical vortices

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    We study linear and nonlinear wave scattering by an optical vortex in a self-defocusing nonlinear Kerr medium. In the linear case, we find a splitting of a plane-wave front at the vortex proportional to its circulation, similar to what occurs in the scattered wave of electrons for the Aharonov-Bohm effect. For larger wave amplitudes, we study analytically and numerically the scattering of a dark-soliton stripe (a nonlinear analog of a small-amplitude wavepacket) by a vortex and observe a significant asymmetry of the scattered wave. Subsequently, a wavefront splitting of the scattered wave develops into transverse modulational instability, ``unzipping'' the stripe into trains of vortices with opposite charges.Comment: 4 pages, 4 figure

    Linking the rates of neutron star binaries and short gamma-ray bursts

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    Short gamma-ray bursts are believed to be produced by both binary neutron star (BNS) and neutron star-black hole (NSBH) mergers. We use current estimates for the BNS and NSBH merger rates to calculate the fraction of observable short gamma-ray bursts produced through each channel. This allows us to constrain merger rates of BNS to RBNS=384−213+431Gpc−3yr−1\mathcal{R}_{\rm{BNS}}=384^{+431}_{-213}{\rm{Gpc}^{-3} \rm{yr}^{-1}} (90%90\% credible interval), a 16%16\% decrease in the rate uncertainties from the second LIGO--Virgo Gravitational-Wave Transient Catalog, GWTC-2. Assuming a top-hat emission profile with a large Lorentz factor, we constrain the average opening angle of gamma-ray burst jets produced in BNS mergers to ≈15∘\approx 15^\circ. We also measure the fraction of BNS and NSBH mergers that produce an observable short gamma-ray burst to be 0.02−0.01+0.020.02^{+0.02}_{-0.01} and 0.01±0.010.01 \pm 0.01, respectively and find that ≳40%\gtrsim 40\% of BNS mergers launch jets (90\% confidence). We forecast constraints for future gravitational-wave detections given different modelling assumptions, including the possibility that BNS and NSBH jets are different. With 2424 BNS and 5555 NSBH observations, expected within six months of the LIGO-Virgo-KAGRA network operating at design sensitivity, it will be possible to constrain the fraction of BNS and NSBH mergers that launch jets with 10%10\% precision. Within a year of observations, we can determine whether the jets launched in NSBH mergers have a different structure than those launched in BNS mergers and rule out whether ≳80%\gtrsim 80\% of binary neutron star mergers launch jets. We discuss the implications of future constraints on understanding the physics of short gamma-ray bursts and binary evolution.Comment: Accepted in Physical Review D: 13 pages, 5 figure
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