279 research outputs found

    Nonlinear Schr\"odinger equation in the Bopp-Podolsky electrodynamics: solutions in the electrostatic case

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    We study the following nonlinear Schr\"odinger-Bopp-Podolsky system {−Δu+ωu+q2ϕu=∣u∣p−2u−Δϕ+a2Δ2ϕ=4πu2 in R3 \begin{cases} -\Delta u + \omega u + q^{2}\phi u = |u|^{p-2}u -\Delta \phi + a^2 \Delta^2 \phi = 4\pi u^2 \end{cases} \hbox{ in }\mathbb{R}^3 with a,ω>0a,\omega>0. We prove existence and nonexistence results depending on the parameters q,pq,p. Moreover we also show that, in the radial case, the solutions we find tend to solutions of the classical Schr\"odinger-Poisson system as a→0a\to0.Comment: 30 pages, the nonexistence result has been improve

    Klein-Gordon-Maxwell System in a bounded domain

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    This paper is concerned with the Klein-Gordon-Maxwell system in a bounded spatial domain. We discuss the existence of standing waves ψ=u(x)e−iωt\psi=u(x)e^{-i\omega t} in equilibrium with a purely electrostatic field E=−∇ϕ(x)\mathbf{E}=-\nabla\phi(x). We assume an homogeneous Dirichlet boundary condition on uu and an inhomogeneous Neumann boundary condition on ϕ\phi. In the "linear" case we characterize the existence of nontrivial solutions for small boundary data. With a suitable nonlinear perturbation in the matter equation, we get the existence of infinitely many solutions.Comment: 17 page

    On fractional Choquard equations

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    We investigate a class of nonlinear Schrodinger equations with a generalized Choquard nonlinearity and fractional diffusion. We obtain regularity, existence, nonexistence, symmetry as well as decays properties.Comment: revised version, 22 page

    Detection of Plasmodium falciparum male and female gametocytes and determination of parasite sex ratio in human endemic populations by novel, cheap and robust RTqPCR assays

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    The presence of Plasmodium falciparum gametocytes in peripheral blood is essential for human to mosquito parasite transmission. The detection of submicroscopic infections with gametocytes and the estimation of the gametocyte sex ratio are crucial to assess the human host potential ability to infect mosquitoes and transmit malaria parasites

    Pull-In Voltage and Stress in Fixed-Fixed Beams of RF MEMS Switches

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    Electrostatically actuated microelectromechanical system (MEMS) switches with fixed- fixed beams were fabricated. FEM modeling was used to calculate the contributions of stress in the fabricated beams from the measured values of pull-in voltage. The reported study provides useful guidelines to optimize the design of fixed-fixed beams, in order to reduce the stress contributions for the successful development of efficient and reliable electrostatically actuated MEMS devices

    Supervised Expert System for Wearable MEMS Accelerometer-Based Fall Detector

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    Falling is one of the main causes of trauma, disability, and death among older people. Inertial sensors-based devices are able to detect falls in controlled environments. Often this kind of solution presents poor performances in real conditions. The aim of this work is the development of a computationally low-cost algorithm for feature extraction and the implementation of a machine-learning scheme for people fall detection, by using a triaxial MEMS wearable wireless accelerometer. The proposed approach allows to generalize the detection of fall events in several practical conditions. It appears invariant to the age, weight, height of people, and to the relative positioning area (even in the upper part of the waist), overcoming the drawbacks of well-known threshold-based approaches in which several parameters need to be manually estimated according to the specific features of the end user. In order to limit the workload, the specific study on posture analysis has been avoided, and a polynomial kernel function is used while maintaining high performances in terms of specificity and sensitivity. The supervised clustering step is achieved by implementing an one-class support vector machine classifier in a stand-alone PC

    TOF Sensor Network for AAL Monitoring Services

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    AbstractThe main goal of Ambient Assisted Living solutions is to provide assistive technologies and services in smart environments allowing to elderly people to have high quality of life. Since Time-Of-Flight vision technologies are increasingly investigated as monitoring solution able to outperform traditional approaches, in this work a monitoring framework based on a Time-Of-Flight sensor network has been investigated with the aim to provide a wide-range solution suitable in several assisted living scenarios. Detector nodes are managed by a low-power embedded PC to process Time-Of-Flight streams and extract features related with person's activities. The feature level of detail is tuned in an application-driven manner in order to optimize both bandwidth and computational resources. The event detection capabilities were validated by using data collected in real-home environments

    Real-time PCR assays for detection and quantification of early P. falciparum gametocyte stages

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    Introduction The use of reverse transcription, quantitative qRT-PCR assays for detection and quantification of late gametocyte stages has revealed the high transmission capacity of the human malaria parasite, Plasmodium falciparum. A full understanding how the parasite adjusts its transmission in response to varying in-host environmental conditions during natural infections requires simultaneous quantification of early and late gametocytes. Here, we describe qRT-PCR assays that are specific for detection and quantification of early-stage gametocytes of P. falciparum. Methods The assays are based on expression of known early gametocyte genes (pfpeg4, pfg27, pfge1, pfge3 and pfgexp5). The specificity of the qRT-PCR assays was tested using purified stage II and stage V gametocytes. These validated assays were used with qRT-PCR assays targeting late stage (pfs25) and all-stage (pfs16) gametocyte-specific transcripts to quantify gametocytes in natural P. falciparum infections and in a controlled human clinical infection study. Results The relative expression of pfpeg4, pfg27 and pfge3, but not of pfge1 and pfgexp5, was significantly higher in purified stage II compared to stage V gametocytes, indicating early gametocyte specificity. In natural infections, 71.2% of individuals had both early and late gametocyte transcripts (pfpeg4/pfg27 plus pfs25), 12.6% harboured only early gametocytes transcripts (pfpeg4/pfg27), and 15.2% had only late gametocytes transcripts (pfs25). In natural infections, the limit of detection was equivalent to 190 and 390 gametocytes/mL blood for pfpeg4 and pfg27, respectively. In infected volunteers, transcripts of pfpeg4 and pfg27 were detected shortly after the onset of blood stage infection, demonstrating the specificity of the assays. Conclusion The pfpeg4 and pfg27 qRT-PCR assays can be used specifically to quantify circulating immature gametocytes. Quantification of early gametocytes will improve understanding of epidemiological processes that modulate P. falciparum transmission and enhance the evaluation of transmission blocking interventions
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