Trust model for certificate revocation in Ad hoc networks

In this paper we propose a distributed trust model for certificate revocation in Adhoc networks. The proposed model allows trust to be built over time as the number of interactions between nodes increase. Furthermore, trust in a node is defined not only in terms of its potential for maliciousness, but also in terms of the quality of the service it provides. Trust in nodes where there is little or no history of interactions is determined by recommendations from other nodes. If the nodes in the network are selfish, trust is obtained by an exchange of portfolios. Bayesian networks form the underlying basis for this model

Stimulated Raman scattering in a non-eigenmode regime

Stimulated Raman scattering (SRS) in plasma in a non-eigenmode regime is studied theoretically and numerically. Different from normal SRS with the eigen electrostatic mode excited, the non-eigenmode SRS is developed at plasma density 0.25nc when the laser amplitude is larger than a certain threshold. To satisfy the phase-matching conditions of frequency and wavenumber, the excited electrostatic mode has a constant frequency around half of the incident light frequency, which is no longer the eigenmode of electron plasma wave. Both the scattered light and the electrostatic wave are trapped in plasma with their group velocities being zero. Super-hot electrons are produced by the non-eigen electrostatic wave. Our theoretical model is validated by particle-in-cell simulations. The SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than

Polychromatic drivers for inertial fusion energy

Although tremendous achievements have been made toward inertial confinement fusion, laser plasma instabilities (LPIs) remain to be an inevitable problem for current drive schemes. To mitigate these instabilities, significant efforts have been paid to produce high-power broadband ultraviolet lasers. However, no practical scheme has been demonstrated up to now for efficient triple-frequency conversion of broadband laser. Here we propose the design of polychromatic drivers for the generation of multicolor beams mainly based upon the optical parametric amplification, which can significantly enhance the third-harmonic conversion efficiency. Each polychromatic light has four colors of monochromatic beamlets with a full spectrum width of 3\%, and the beamlet colors of any two adjacent flanges are different. The suppression effects of such polychromatic lights have been investigated via large scale particle-in-cell simulations, which indicate that more than 35\% of the incident energy can be saved from the LPIs compared with monochromatic lasers for the direct-drive scheme, or high-density filled target for the indirect-drive scheme. The proposed polychromatic drivers are based on the matured technologies, and thus may pave the way towards realization of robust and high-efficiency fusion ignition

Plasma modulator for high-power intense lasers

A type of plasma-based optical modulator is proposed for the generation of broadband high-power laser pulses. Compared with normal optical components, plasma-based optical components can sustain much higher laser intensities. Here we illustrate via theory and simulation that a high-power sub-relativistic laser pulse can be self-modulated to a broad bandwidth over 100% after it passes through a tenuous plasma. In this scheme, the self-modulation of the incident picoseconds sub-relativistic pulse is realized via stimulated Raman forward rescattering in the quasi-linear regime, where the stimulated Raman backscattering is heavily dampened. The optimal laser and plasma parameters for this self-modulation have been identified. For a laser with asub-relativistic intensity of I ∼ 1017W/cm2, the time scale for the development of self-modulation is around 103 light periods when stimulated Raman forward scattering has been fully developed. Consequently, the spatial scale required for such a self-modulation is in the order of millimeters. For a tenuous plasma, the energy conversion efficiency of this self-modulation is around 90%. Theoretical predictions are verified by both one-dimensional and two-dimensional particle-in-cell simulations

The Correctional Model of Population Development Equation

ABSTRACT The problem of population development has always been the key problem of restricting the development of our country. In order to increase the prediction accuracy, we analyze the exponential model, logistic model and continuous model. Also, the improved discrete population development model is provided to control the quantity and improve the quality of population

Suppression of parametric instabilities in inhomogeneous plasma with multi-frequency light

The development of parametric instabilities in a large scale inhomogeneous plasma with an incident laser beam composed of multiple frequency components is studied theoretically and numerically. Firstly, theoretical analyses of the coupling between two laser beamlets with certain frequency difference δω 0 for parametric instabilities is presented. It suggests that the two beamlets will be decoupled when δω 0 is larger than certain thresholds, which are derived for stimulated Raman scattering, stimulated Brillouin scattering, and two plasmon decay, respectively. In this case, the parametric instabilities for the two beamlets develop independently and can be controlled at a low level provided the laser intensity for individual beamlet is low enough. Secondly, numerical simulations of parametric instabilities with two or more beamlets (N ∼ 20) have been carried out and the above theory model is validated. Simulations confirm that the development of parametric instabilities with multiple beamlets can be controlled at a low level, provided the threshold conditions for δω 0 is satisfied, even though the total laser intensity is as high as ∼10 15 W cm -2. With such a laser beam structure of multiple frequency components and total bandwidth of a few percentages (⪆4%ω 0), the parametric instabilities can be well-controlled

Absolute instability modes due to rescattering of stimulated Raman scattering in a large nonuniform plasma

Absolute instability modes due to rescattering of SRS in a large nonuniform plasma is studied theoretically and numerically. The backscattered light of convective SRS can be considered as a pump light with a finite bandwidth. The different frequency components of the backscattered light can be coupled to develop absolute stimulated Raman scattering (SRS) and two plasmon decay (TPD) instability near their quarter-critical densities via rescattering process. The absolute SRS mode develops a Langmuir wave with a high phase velocity about c/ √3 with c the light speed in vacuum. Given that most electrons are at low velocities in the linear stage, the absolute SRS mode grows with much weak Landau damping. When the interaction evolves into the nonlinear regime, the Langmuir wave can heat abundant electrons up to a few hundred keV. Our theoretical model is validated by particle-in-cell simulations. The absolute instabilities may play a considerable role for the indirect-drive experiments of inertial confined fusion

Genome-Wide Profiling of Prognostic Alternative Splicing Signature in Colorectal Cancer

Background: This study was to explore differential RNA splicing patterns and elucidate the function of the splice variants served as prognostic biomarkers in colorectal cancer (CRC).Methods: Genome-wide profiling of prognostic alternative splicing (AS) events using RNA-seq data from The Cancer Genome Atlas (TCGA) program was conducted to evaluate the roles of seven AS patterns in 330 colorectal cancer cohort. The prognostic predictors models were assessed by integrated Cox proportional hazards regression. Based on the correlations between survival associated AS events and splicing factors, splicing networks were built.Results: A total of 2,158 survival associated AS events in CRC were identified. Interestingly, most of these top 20 survival associated AS events were adverse prognostic factors. The prognostic models were built by each type of splicing patterns, performing well for risk stratification in CRC patients. The area under curve (AUC) of receiver operating characteristic (ROC) for the combined prognostic predictors model could reach 0.963. Splicing network also suggested distinguished correlation between the expression of splicing factors and AS events in CRC patients.Conclusion: The ideal prognostic predictors model for risk stratification in CRC patients was constructed by differential splicing patterns of 13 genes. Our findings enriched knowledge about differential RNA splicing patterns and the regulation of splicing, providing generous biomarker candidates and potential targets for the treatment of CRC

Ultrafast phenomena and terahertz waves : introduction

In this introduction, we provide an overview of the papers that were accepted for publication in the feature issue on ultrafast phenomena and terahertz (THz) waves. This feature issue presents cutting-edge research on ultrafast phenomena and highlights recent developments in THz technology