Robust variable selection in partially varying coefficient single-index model

By combining basis function approximations and smoothly clipped absolute deviation (SCAD) penalty, this paper proposes a robust variable selection procedure for a partially varying coefficient single-index model based on modal regression. The proposed procedure simultaneously selects significant variables in the parametric components and the nonparametric components. With appropriate selection of the tuning parameters, we establish the theoretical properties of our procedure, including consistency in variable selection and the oracle property in estimation. Furthermore, we also discuss the bandwidth selection and propose a modified expectation-maximization (EM)-type algorithm for the proposed estimation procedure. The finite sample properties of the proposed estimators are illustrated by some simulation examples.The research of Zhu is partially supported by National Natural Science Foundation of China (NNSFC) under Grants 71171075, 71221001 and 71031004. The research of Yu is supported by NNSFC under Grant 11261048

M-SSE: an effective searchable symmetric encryption with enhanced security for mobile devices

Searchable Encryption (SE) allows mobile devices with limited computing and storage resources to outsource data to an untrusted cloud server. Users are able to search and retrieve the outsourced, however, it suffers from information and privacy leakage. The reason is that most of the previous works rely on the single cloud model, which allows that the cloud server get all the search information from users. In this paper, we present a new scheme M-SSE that achieves both forward and backward security based on a multi-cloud technique. The new scheme is secure against both adaptive file injection attack and size pattern attack by utilizing multiple cloud servers. Experiment results show that our scheme is effective compared with the other existing schemes

Ultrarelativistic electrons in counterpropagating laser beams

The dynamics and radiation of ultrarelativistic electrons in strong counterpropagating laser beams are investigated. Assuming that the particle energy is the dominant scale in the problem, an approximate solution of classical equations of motion is derived and the characteristic features of the motion are examined. A specific regime is found with comparable strong field quantum parameters of the beams, when the electron trajectory exhibits ultrashort spike-like features, which bears great significance to the corresponding radiation properties. An analytical expression for the spectral distribution of spontaneous radiation is derived in the framework of the Baier-Katkov semiclassical approximation based on the classical trajectory. All the analytical results are further validated by exact numerical calculations. We consider a non-resonant regime of interaction, when the laser frequencies in the electron rest frame are far from each other, avoiding stimulated emission. Special attention is devoted to settings when the description of radiation via the local constant field approximation fails and to corresponding spectral features. Periodic and non-periodic regimes are considered, when lab frequencies of the laser waves are always commensurate. The sensitivity of spectra with respect to the electron beam spread, focusing and finite duration of the laser beams is explored.Comment: 23 papes, 10 figure

Effect of montmorillonite on arsenic accumulation in common carp

The effect of montmorillonite (MMT) on dietary arsenic (As(III)) accumulation in tissues of common carp was investigated. Growth rates and survival do not appear to be sensitive indicators of dietary As(III) toxicity under lower exposure concentration. However, the toxicity increases as As(III) exposure concentration increase, and this can be alleviated with added MMT concentration. Exposure of common carp to dietary As(III) resulted in a significant As(III) accumulation in the tissues of common carp in the order: intestine>bone>gill>liver>muscle>brain (P<0.05), indicating accumulation of these tissues. When fed with MMT, there was a reduction in As(III) concentration of these tissues compared with the control group. The ratio of oxidized glutathione to reduced glutathione (GSSG/GSH) revealed a significant effect with MMT concentration (1.0%) (p<0.05) and post-hoc analysis also revealed that the group treated with MMT exhibited a decrease in the ratio of GSSG/GSH when compared to the fish not treated with MMT. Moreover, the addition of MMT to the diet with As(III) decreased metallothionein concentration. The added dietary MMT was therefore clearly protective against the bioaccumulation of As(III).Key words: Montmorillonite, arsenic, common carp

High-brilliance ultra-narrow-band x-rays via electron radiation in colliding laser pulses

A setup of a unique x-ray source is put forward employing a relativistic electron beam interacting with two counter-propagating laser pulses in the nonlinear few-photon regime. In contrast to Compton scattering (CS) sources, the envisaged x-ray source exhibits an extremely narrow relative bandwidth of $10^{-5}$ to $10^{-4}$, comparable to the x-ray free-electron laser (XFEL). The brilliance of the x-rays can be $2 - 3$ orders of magnitude higher than a state-of-the-art CS source, while the angle spreading of the radiation is much smaller. By tuning the laser intensities and the electron energy, one can realize either a single peak or a comb-like x-ray source around keV energy. The laser intensity and the electron energy in the suggested setup are rather moderate, rendering this scheme compact and table-top size, as opposed to XFEL and synchrotron infrastructures