Silicon-substrate microelectrode arrays for parallel recording ofneural activity in peripheral and cranial nerves

A new process for the fabrication of regeneration microelectrode arrays for peripheral and cranial nerve applications is presented. This type of array is implanted between the severed ends of nerves, the axons of which regenerate through via holes in the silicon and are thereafter held fixed with respect to the microelectrodes. The process described is designed for compatibility with industry-standard CMOS or BiCMOS processes (it does not involve high-temperature process steps nor heavily-doped etch-stop layers), and provides a thin membrane for the via holes, surrounded by a thick silicon supporting rim. Many basic questions remain regarding the optimum via hole and microelectrode geometries in terms of both biological and electrical performance of the implants, and therefore passive versions were fabricated as tools for addressing these issues in on-going work. Versions of the devices were implanted in the rat peroneal nerve and in the frog auditory nerve. In both cases, regeneration was verified histologically and it was observed that the regenerated nerves had reorganized into microfascicles containing both myelinated and unmyelinated axons and corresponding to the grid pattern of the via holes. These microelectrode arrays were shown to allow the recording of action potential signals in both the peripheral and cranial nerve settings, from several microelectrodes in parallel     

Inertia-preserving secant updates

Corrections to the last two equations of Ref. 1 are given.     

Toward customer-usable all-optical networks

Although all-optical networks were being thought about almost ten years ago, until recently it would have been premature to talk about such networks as being truly usable. Now, ways of removing most of the roadblocks to practicality have come clearly into view. It is generally agreed that time-division packet switching in the form of asynchronous transfer mode (ATM) is likely to constitute the next generation of networking, both local and wide area; but what about the generation after that? While people are evolving SONET/ATM, the present Internet, and such emerging ambitions as the National Information Infrastructure (NII), in order to serve the needs anticipated for the next decade, optical fiber is being steadily installed at a rate of 700 miles per day in the United States alone. Furthermore, this resource is being extended steadily outward from the telco or cable provider backbone into customer premises, so that within the lifetime of the ATM generation, we may expect extremely rich fiber connectivity of a large number of homes and offices     

A neural network control system with parallel adaptive enhancementsapplicable to nonlinear servomechanisms

In this paper, we present a technique for using an additional parallel neural network to provide adaptive enhancements to a basic fixed neural network-based nonlinear control system. This proposed parallel adaptive neural network control system is applicable to nonlinear dynamical systems of the type commonly encountered in many practical position control servomechanisms. Properties of the controller are discussed, and it is shown that if Gaussian radial basis function networks are used for the additional parallel neural network, uniformly stable adaptation is assured and the approximation error converges to zero asymptotically. In the paper, the effectiveness of the proposed parallel adaptive neural network control system is demonstrated in real-time implementation experiments for position control in a servomechanism with asymmetrical loading and changes in the load     

Evolution of flat-panel displays

The evolution in performance and manufacturability of liquid-crystal displays has created a new reality in the electronic information displays industry. LCD's now outnumber all other flat-panel displays in production volume, by more than two orders of magnitude. LCD's may equal CRT's in market sales by the year 2000. However, LCD's are still an order of magnitude more expensive than comparable performing CRT's. LCD's are enabling new products, such as personal digital assistants, moving map navigators, picture telephones, etc., which could not he readily done with CRTs because of their size and sensitivity to ambient illuminations. The LCD technology in various modes, from passive twisted nematic to active matrix, is being used in all product sizes, from the 0.7-in camcorder viewfinder to the 14-in full-color display with XGA resolution. Full color is very important in future products and any flat-panel display technology without it will be relegated to niche markets     

FDTD simulation of microwave sintering of ceramics in multimodecavities

Microwave sintering of ceramics in multimode cavities, particularly the use of picket-fence arrangements, has recently received considerable attention. Various types of ceramics have been successfully sintered and, in some cases, a desirable and unique “microwave effect” has been observed. At present, various aspects of the sintering profess such as preparation of sample sizes and shapes, types of insulations, and the desirability of including a process stimulus such as SiC rods are considered forms of art and highly dependent on human expertise. The simulation of realistic sintering experiments in a multimode cavity may provide an improved understanding of critical parameters involved and allow for the development of guidelines towards the optimization of the sintering process. In this paper, we utilize the FDTD technique to model various geometrical arrangements and material compatibility aspects in multimode microwave cavities and to simulate realistic sintering experiments. The FDTD procedure starts with the simulation of a field distribution in multimode microwave cavities that resembles a set of measured data using liquid crystal sheets. Also included in the simulation is the waveguide feed as well as a ceramic loading plate placed at the base of the cavity     

Describing collaborative forms: a profile of the team-writingprocess

The paper examines collaborative writing practices students in the Air Force Institute of Technology's Graduate School of Logistics and Acquisition Management use to produce team-authored theses. In analyzing how student writing teams plan, execute, and assess writing activities, the researchers identify and describe some of the forms that collaboration takes, thereby successfully connecting their work within a broader research continuum concerning collaborative writing, particularly when applied in academic settings     

Best structures for deep submicrometer (0.1-0.3 μm) MOS devices

Summary form only given. The LDD-type structure has begun to encounter difficulties in satisfying transistor requirements in manufacturing due to a basic conflict between the need to have a graded drain profile for hot carrier suppression and the requirements for manufacturability and performance which place emphasis on a shallow, steeply profiled drain. One approach for overcoming this conflict and limitation is a MOS transistor structure called the hot-carrier suppressed (HCS) MOSFET. In this approach, a lower doped drain region is placed behind, or above, the shallow, heavier doped drain region rather than being placed adjacent to the channel region. This structure is described in detail, and its simulated performance compared with that of the LDD and conventional MOSFET structures     

Rainbow Net analysis of VAXcluster system availability

A system modeling technique, Rainbow Nets, is used to evaluate the availability and mean-time-to-interrupt of the VAXcluster. These results are compared to the exact analytic results showing that reasonable accuracy is achieved through simulation. The complexity of the Rainbow Net implemented for the VAXcluster does not increase as the number of processors increases, but remains constant. This is unlike a Markov model which increases in size exponentially. The constancy is achieved by using tokens with identity attributes (items) that can have additional attributes associated with them (features) which can exist in multiple states. The time to perform the simulation increases, but this is a polynomial increase rather than exponential. With Rainbow Nets, there is no restriction on distributions used for transition firing times. This freedom allows real situations to be modeled more accurately by choosing the distribution which best fits the system performance. This eliminates the need to make the many simplifying assumptions that are typically required to keep analytic calculations from becoming intractable