Xidian University

About: Xidian University is a education organization based out in Xi'an, China. It is known for research contribution in the topics: Antenna (radio) & Computer science. The organization has 32099 authors who have published 38961 publications receiving 431820 citations. The organization is also known as: University of Electronic Science and Technology at Xi'an & Xīān Diànzǐ Kējì Dàxué.

Wavelet Fusion on Ratio Images for Change Detection in SAR Images

Abstract: This letter presents a novel method based on wavelet fusion for change detection in synthetic aperture radar (SAR) images. The proposed approach is applied to generate the difference image (DI) by using complementary information from mean-ratio and log-ratio images. To restrain the background (unchanged areas) information and enhance the information of changed regions in the fused DI, fusion rules based on weight averaging and minimum standard deviation are chosen to fuse the wavelet coefficients for low- and high-frequency bands, respectively. Experiments on real SAR images confirm that the proposed approach does better than the mean-ratio, log-ratio, and Rayleigh-distribution-ratio operators.

CPW-Fed S-Shaped Slot Antenna for Broadband Circular Polarization

Abstract: In this letter, a new broadband circularly polarized (CP) printed-slot antenna fed by a coplanar waveguide (CPW) is designed and fabricated. To achieve a broadband CP wave, an S-shaped slot is employed in the ground to produce orthogonal surface currents for right-hand circular polarization (RHCP). Furthermore, an L-shaped radiator is introduced to obtain a broad impedance bandwidth that can cover the whole CP bandwidth completely. Good agreement is achieved between the simulation and measurement, which shows that the presented antenna covers an impedance bandwidth (S11 <; -10 dB) of 104% from 1.78 to 5.64 GHz, and a 3-dB axial-ratio bandwidth (ARBW) of 58.6% from 2.85 to 5.21 GHz. The surface current analysis and a parametric study of the design are also carried out to explain the mechanism of circular polarization.

Electrodeposition of silver nanoparticles on a zinc oxide film: improvement of amperometric sensing sensitivity and stability for hydrogen peroxide determination

Abstract: A strategy to fabricate a hydrogen peroxide (HP) sensor is developed by electrodepositing silver nanoparticles (Ag NPs) on a modified glassy carbon electrode (GCE) with a zinc oxide (ZnO) film. The Ag NPs/ZnO/GCE has been characterized by scanning electron microscopy, cyclic voltammetry, and chronoamperometry. It has been found that the Ag NPs synthesized in the presence of ZnO film provide an electrode with enhanced sensitivity and excellent stability. The sensitivity to HP is enhanced 3-fold by using Ag NPs/ZnO/GCE compared to Ag NPs/GCE. The HP sensor exhibits good linear behavior in the concentration range 2 µM to 5.5 mM for the quantitative analysis of HP with a detection limit of 0.42 µM (S/N = 3).

Predicting subsequent relapse by drug-related cue-induced brain activation in heroin addiction: an event-related functional magnetic resonance imaging study

Abstract: Abnormal salience attribution is implicated in heroin addiction. Previously, combining functional magnetic resonance imaging (fMRI) and a drug cue-reactivity task, we demonstrated abnormal patterns of subjective response and brain reactivity in heroin-dependent individuals. However, whether the changes in cue-induced brain response were related to relapse was unknown. In a prospective study, we recruited 49 heroin-dependent patients under methadone maintenance treatment, a gold standard treatment (average daily dose 41.8 ± 16.0 mg), and 20 healthy subjects to perform the heroin cue-reactivity task during fMRI. The patients' subjective craving was evaluated. They participated in a follow-up assessment for 3 months, during which heroin use was assessed and relapse was confirmed by self-reported relapse or urine toxicology. Differences between relapsers and non-relapsers were analyzed with respect to the results from heroin-cue responses. Compared with healthy subjects, relapsers and non-relapsers commonly demonstrated significantly increased brain responses during the processing of heroin cues in the mesolimbic system, prefrontal regions and visuospatial-attention regions. However, compared with non-relapsers, relapsers demonstrated significantly greater cue-induced craving and the brain response mainly in the bilateral nucleus accumbens/subcallosal cortex and cerebellum. Although the cue-induced heroin craving was low in absolute measures, the change in craving positively correlated with the activation of the nucleus accumbens/subcallosal cortex among the patients. These findings suggest that in treatment-seeking heroin-dependent individuals, greater cue-induced craving and greater specific regional activations might be related to reward/craving and memory retrieval processes. These responses may predict relapse and represent important targets for the development of new treatment for heroin addiction.