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An N200 speller integrating the spatial profile for the detection of the non-control state

Dan Zhang, Huaying Song, Honglai Xu, Wei Wu, Shangkai Gao and Bo Hong — 2012-03-14T00:00:00Z

The N200 speller is a recently developed non-flashing visual brain–computer interface (BCI) paradigm utilizing the overt attention modulation effects on motion-onset visual evoked potentials (mVEP). In this study, a novel algorithm is proposed and applied in an online N200 speller. The proposed algorithm integrates the spatial information of the speller matrix to provide a more precise description of the mVEP response patterns, which is defined as the ‘spatial profile’. More importantly, only control state data are used in the algorithm to train a classifier that nonetheless can detect the non-control state effectively. Compared to an algorithm with similar structure but not using the spatial profile information, the proposed algorithm shows significantly higher performance for the recognition of the non-control state while achieving a comparable performance for classifying different control states. Offline and online classification results show that the proposed N200 speller is ...

One-pot synthesis of PVA-capped silver nanoparticles their characterization and biomedical application

2012-03-14T00:00:00Z

The rapid one-pot synthesis of silver nanoparticles (SNPs) at room temperature by using hydrazine hydrate as reducing agent and polyvinyl alcohol as stabilizing agent is reported. The SNPs were characterized with UV-visible (UV-Vis) spectroscopy, x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The synthesized silver nanoparticle shows surface plasmon resonance at 410 nm. The XRD reveals face-centered cubic (FCC) structure of SNPs. FE-SEM, AFM and TEM show that nanoparticles have spherical morphology with diameters in the range of 10–60 nm. The antimicrobial activity of synthesized hybrid material against strains of four different bacteria ( Bacillus cereus, Escherichia coli, Staphylococus aureus, Proteus vulgaris ), that are commonly found in hospitals has been studied. The results indicate that such particles have potential applications in biotechnology and biomedical sc...

China’s water–energy nexus: greenhouse-gas emissions from groundwater use for agriculture

2012-03-14T00:00:00Z

China is the world’s largest emitter of greenhouse gases (GHGs) and the agricultural sector in China is responsible for 17–20% of annual emissions and 62% of total freshwater use. Groundwater abstraction in China has increased rapidly from 10 km 3 yr −1 in the 1950s to more than 100 km 3 yr −1 in the 2000s, such that roughly 70% of the irrigated area in northern China is now groundwater-fed. Pumping of water for irrigation is one of the most energy consuming on-farm processes; however, to date this source of GHG emissions in China and elsewhere has been relatively neglected. We derive the first detailed estimate of GHG emissions from groundwater pumping for irrigation in China, using extensive village survey data from 11 provinces, broadly representative of the situation during the mid-2000s. The 11 provinces cover roughly half of China’s irrigated cropland and we upscale to the national level using government statistics for the remaining ...

Formation and growth of nanocavities and cavities induced by He + implantation in silicon

My Anh Nguyen, Marie-Odile Ruault and Franck Fortuna — 2012-03-14T00:00:00Z

Nanocavities and cavities are known to be efficient gettering sites for metallic impurities in silicon. Here, we report results from implanted ##IMG## [http://ej.iop.org/icons/Entities/lang.gif] {lang} 100 ##IMG## [http://ej.iop.org/icons/Entities/rang.gif] {rang} silicon at room temperature with 50 keV helium ions at a dose of 3×10 16 cm −2 . Due to its low solubility, He segregates in gas-vacancy complexes and forms nanobubbles. Then, during an N 2 ambient annealing at 800 °C using either rapid thermal annealing (RTA) or conventional furnace annealing, nanobubbles grow and He is released from the nanobubbles by gas exodiffusion, leading to (nano)cavities' formation. (Nano)cavities and residual defects were observed by transmission electron microscopy (TEM). The fraction of retained helium was shown to decr...

Nd–Fe–B-based anisotropic nanocrystalline hard magnetic alloys

2012-03-14T00:00:00Z

Nd 10.5 Fe 83.5− x Ga x B 6 ( x =1.5, 3 and 4.5) ribbons were prepared by melt-spinning method with various wheel speeds from 5 to 40 m s −1 . Strong crystallographic texture with c-axis of Nd 2 Fe 14 B crystallites along normal of the ribbon surface was observed. The texture degree can be enhanced by decreasing the quenching rate during solidification of the melt and by increasing the concentration of Ga. Preferred orientation of the nanocrystallites with their size of 10–30 nm is obtained not only by controlling the quenching rate of the melt during solidification but also by appropriately annealing the over-quenched ribbons. The texture of microstructure clearly affects magnetic anisotropy of the ribbons. With increasing concentration of Ga, the magnetic anisotropy of the ribbons is considerably increased. The coercivity above 6.5 kOe and maximum energy products larger than 15 MGOe can be achieve...

A novel BCI based on ERP components sensitive to configural processing of human faces

Yu Zhang, Qibin Zhao, Jin Jing, Xingyu Wang and Andrzej Cichocki — 2012-03-14T00:00:00Z

This study introduces a novel brain–computer interface (BCI) based on an oddball paradigm using stimuli of facial images with loss of configural face information (e.g., inversion of face). To the best of our knowledge, till now the configural processing of human faces has not been applied to BCI but widely studied in cognitive neuroscience research. Our experiments confirm that the face-sensitive event-related potential (ERP) components N170 and vertex positive potential (VPP) have reflected early structural encoding of faces and can be modulated by the configural processing of faces. With the proposed novel paradigm, we investigate the effects of ERP components N170, VPP and P300 on target detection for BCI. An eight-class BCI platform is developed to analyze ERPs and evaluate the target detection performance using linear discriminant analysis without complicated feature extraction processing. The online classification accuracy of 88.7% and information transfer rate of 38.7 bits...

Crystallization and magnetic properties of amorphous iron–chromium oxide nanoparticles synthesized by sonochemistry

2012-03-14T00:00:00Z

Amorphous iron–chromium oxide Fe 2− x Cr x O 3 ( x =0, 0.05, 0.10, 0.15, 0.20) nanoparticles were synthesized by sonochemical method at 80 °C. Crystallization process of the annealed samples showed a strong ferromagnetic behavior due to the existence of the maghemite phase. The effect of chromium replacing iron in the crystallization process of Fe 2− x Cr x O 3 nanoparticles was systematically studied by adjusting initial concentration of Cr 3+ . The activation energy of the samples deduced from thermal analysis and increased with doping chromium showed that the existence of chromium can significantly slow down the ageing effect of the amorphous iron oxide.

Affleck-Dine baryogenesis in inflating curvaton scenario with ##IMG## [http://ej.iop.org/icons/Entities/calO.gif] {Script O} (10–10 2 TeV) mass moduli curvaton

Kazuyuki Furuuchi and Chia-Min Lin — 2012-03-14T00:00:00Z

We study the Affleck-Dine (AD) baryogenesis in the inflating curvaton scenario, when the curvaton is a moduli field with ##IMG## [http://ej.iop.org/icons/Entities/calO.gif] {Script O} (10–10 2 TeV) mass. A moduli field with such mass is known to be free from the Polonyi problem, and furthermore its decay products can explain the present cold dark matter abundance. In our scenario, it further explains the primordial curvature perturbation and the present baryon density all together. The current observational bound on the baryon isocurvature perturbation, which severely constrains the AD baryogenesis with the original oscillating moduli curvaton scenario, is shown to put practically negligible constraint if we replace the oscillating curvaton with the inflating curvaton.

Synthesis and investigations on CO catalytic oxidation activity of nanostructured Ce 0.5 Zr 0.5 O 2 prepared by combustion method using polyvinyl alcohol

Ngoc Nhiem Dao and Minh Dai Luu — 2012-03-14T00:00:00Z

Nanostructured Ce 0.5 Zr 0.5 O 2 samples were synthesized by the combustion of the gel obtained from a mixture of polyvinyl alcohol (PVA) and metal nitrates at a temperature as low as 600 °C. The prepared samples were investigated by x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Their specific surface areas were determined from N 2 adsorption measurement at 77 K by Brunauer–Emmet–Teller (BET) method and their CO catalytic oxidation activities were investigated using a Landcom II instrument. The XRD and FE-SEM results revealed that Ce 0.5 Zr 0.5 O 2 nanocrystallines began to grow isotropically at 600 °C with the nanostructure found in all prepared samples. Further thermal treatment at 600 °C for 2 h yields the single crystalline phase Ce 0.5 Zr 0.5 O 2 nanostructured samples with average crystalline size < 50 nm and specific surface area of about 73 ...

Cosmological constraints on extended Galileon models

Antonio De Felice and Shinji Tsujikawa — 2012-03-14T00:00:00Z

The extended Galileon models possess tracker solutions with de Sitter attractors along which the dark energy equation of state is constant during the matter-dominated epoch, i.e. w DE = −1− s , where s is a positive constant. Even with this phantom equation of state there are viable parameter spaces in which the ghosts and Laplacian instabilities are absent. Using the observational data of the supernovae type Ia, the cosmic microwave background (CMB), and baryon acoustic oscillations, we place constraints on the tracker solutions at the background level and find that the parameter s is constrained to be s = 0.034 −0.034 +0.327 (95 % CL) in the flat Universe. In order to break the degeneracy between the models we also study the evolution of cosmological density perturbations relevant to the large-scale structure (LSS) and the Integrated-Sachs-Wolfe (ISW) effect in CMB. We show that, depending on the model parameters, the...