Noninvasive Neural Prostheses Using Mobile and Wireless EEG

Neural prosthetic technologies have helped many patients by restoring vision, hearing, or movement and relieving chronic pain or neurological disorders. While most neural prosthetic systems to date have used invasive or implantable devices for patients with inoperative or malfunctioning external body parts or internal organs, a much larger population of ldquohealthyrdquo people who suffer episodic or progressive cognitive impairments in daily life can benefit from noninvasive neural prostheses. For example, reduced alertness, lack of attention, or poor decision-making during monotonous, routine tasks can have catastrophic consequences. This study proposes a noninvasive mobile prosthetic platform for continuously monitoring high-temporal resolution brain dynamics without requiring application of conductive gels on the scalp. The proposed system features dry microelectromechanical system electroencephalography sensors, low-power signal acquisition, amplification and digitization, wireless telemetry, online artifact cancellation, and signal processing. Its implications for neural prostheses are examined in two sample studies: 1) cognitive-state monitoring of participants performing realistic driving tasks in the virtual-reality-based dynamic driving simulator and 2) the neural correlates of motion sickness in driving. The experimental results of these studies provide new insights into the understanding of complex brain functions of participants actively performing ordinary tasks in natural body positions and situations within real operational environments.     

Development of wireless brain computer interface with embedded multitask scheduling and its application on real-time driver's drowsiness detection and warning

Biomedical signal monitoring systems have been rapidly advanced with electronic and information technologies in recent years. However, most of the existing physiological signal monitoring systems can only record the signals without the capability of automatic analysis. In this paper, we proposed a novel brain-computer interface (BCI) system that can acquire and analyze electroencephalogram (EEG) signals in real-time to monitor human physiological as well as cognitive states, and, in turn, provide warning signals to the users when needed. The BCI system consists of a four-channel biosignal acquisition/amplification module, a wireless transmission module, a dual-core signal processing unit, and a host system for display and storage. The embedded dual-core processing system with multitask scheduling capability was proposed to acquire and process the input EEG signals in real time. In addition, the wireless transmission module, which eliminates the inconvenience of wiring, can be switched between radio frequency (RF) and Bluetooth according to the transmission distance. Finally, the real-time EEG-based drowsiness monitoring and warning algorithms were implemented and integrated into the system to close the loop of the BCI system. The practical online testing demonstrates the feasibility of using the proposed system with the ability of real-time processing, automatic analysis, and online warning feedback in real-world operation and living environments.     

Comparison between oxide-reduced and water-atomized copper powders used in making sintered wicks of heat pipe

Oxide-reduced copper powder can be produced efficiently at low cost. The volume shrinkage, porosity, maximum pore size, permeability and thermal conductivity of wicks sintered from two oxide-reduced （OR） powders were compared with one from water-atomized （WA） powder. The green specimens were sintered at temperatures from 800 to 1000 ℃ in a tube furnace under a reduction stream of 10% hydrogen and 90% argon. The results show that the property variations of OR - 100 and WA wicks due to porosity changes have a similar tendency and range. Nine hundred degree celsius is a recommended sintering temperature for producing ideal wicks for use in heat pipes. A smaller maximum pore size can be obtained by increasing the green density.2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.     

1,2-dimetallacyclo-1,2-hexyne compounds of molybdenum and tungsten

From the reactions between 1,4-dilithiobutane and 1,2-M₂Cl₂(NMe₂)₄ compounds in hydrocarbon solvents, the 1,2-dimetallacyclo-1,2-hexyne compounds M₂(CH₂)₄(NMe₂)₄(MM), where M = Mo and W, have been obtained as yellow—orange, volatile microcrystalline compounds. Spectroscopic data are consistent with expectations based on previous studies of gauche 1,2-M₂R₂(NMe₂)₄ compounds in solution and a structural model based on the observed molecular structure of 1,2-Mo₂Et₂(NMe₂)₄ is presented and compared with the observed molecular structure of Mo₂(CH₂)₄(NMe₂)₄ found in the solid state. Pertinent bond distances (Å) and angles (°) are: Mo—Mo = 2.200(1), Mo—N = 1.96(1) (averaged), Mo—C = 2.165(8) (averaged), Mo—Mo—N = 105(1), Mo—Mo—C = 97(1).     

Quantum well lasers

Basic issues of quantum well lasers, such as the gain, temperature dependence of the threshold current and modulation characteristics are reviewed and discussed.     

Bis(dimethylphosphino)methane (dmpm) complexes of iron,molybdenum and chromium: X-ray crystal structures of FeCr(CO)6(μ-dmpm)2 and Fe2(CO)4(μ-CO)(μ-dmpm)2

The photolysis of Fe(η¹-dmpm)(dmpm)₂ [dmpm = bis(dimethylphosphino) methane) with Cr(CO)₆ and Fe(CO)₅ under UV irradiation produces FeCr(CO)₆(μ-dmpm)₂, Fe₂(CO)₆(μ-CO)(μ-dmpm) and Fe₂(CO)₄(μ-CO)(μ-dmpm)₂ respectively. The interaction of Mo(CO)₃(MeCN)₃ and (C₇H₈)Cr(CO)₃ with dmpm produces Mo₂(CO)₆(μ-dmpm)₃ and cis-Cr(CO)₂(dmpm)₂ respectively. The X-ray crystal structure of FeCr(CO)₆(μ-dmpm)₂ shows the molecule to contain a trigonal bipyramidal Fe(CO)₃P₂ unit plus a square pyramidal Cr(CO)₃P₂ unit held closely together by the methylene bridges of the dmpm ligands with steric compression between the CO groups causing distortions from ideal geometry in each case. The Cr … Fe distance is 3.111(6) Å and there seems to be little structural evidence of any form of interaction between the 16e Cr(O) centre and the Fe-containing unit. The structure of Fe₂(CO)₄(μ-CO)(μ-dmpm)₂ contains a symmetrical μ₂-carbonyl and a single bond between the two symmetry related (m) iron atoms. The Fe … Fe distance is 2.719(4) Å.     

Algorithms for compressing compound document images with large text/background overlap

Two algorithms are presented for compressing image documents, with a high compression ratio for both colour and monochromatic compound document images. The proposed algorithms apply a new method of segmentation to separate the text from the image in a compound document in which the text overlaps the background. The segmentation method classifies document images into three planes: the text plane, the background (non-text) plane and the text's colour plane, each of which are processed using different compression techniques. The text plane is compressed using the pattern matching technique, called JB2. Wavelet transform and zerotree coding are used to compress the background plane and the text's colour plane. Assigning bits for different planes yields high-quality compound document images with both a high compression ratio and well presented text. The proposed algorithms greatly outperform two well known image compression methods, JPEG and DjVu, and enable the effective extraction of the text from a complex background, achieving a high compression ratio for compound document images.     

Cubic Ramanujan graphs

A fimily of cubic Ramanujan graph is explicitly constructed. They are realized as Cayley graphs of a certain free group acting on the 3-regular tree; this group is obtained from a definite quaternion algebra that splits at the prime 2 and has a maximal order of class number 1.     

Suppression of lateral autodoping from arsenic buried layer byselective epitaxy capping

An effective way to suppress lateral autodoping from the heavily arsenic-doped buried layer during silicon epitaxy is described. By using this simple technique, collector-substrate capacitance (C_cs) is minimized. This process is ideal for high-speed BiCMOS and bipolar technology. A thin epilayer is first grown selectively on the buried layer. This selectively grown film suppresses the release of arsenic during the subsequent epi growth. High-performance bipolar devices have been fabricated in this epi material. Electrical measurements indicate that the crystalline quality is excellent