Optically achieved p-i-n diode switch utilizing a two-dimensionallaser array at 808 nm as an optical source

The design, fabrication, and application of optically activated switches is described. A 0.25-mm-thick Si p-i-n diode, 3.0 mm in diameter, was tested using an 808-nm 2-D diode laser array (measuring about 2 mm×5 mm) as an optical source. Preliminary testing of a 0.25-mm-thick device has demonstrated a holding voltage of 1000 V and a conduction of 10 A upon activation with 200 W of optical power (the pulse width was 10 μs). The same device, while being pulse biased to 2.0 kV, has demonstrated 20-A pulses (100-ns pulse width) with less than 10-ns risetime. The laser peak power was 500 W     

Signal transduction abnormalities in Alzheimer's disease: evidence of a pathogenic stimuli

Hippocampal and select cortical neuronal populations in Alzheimer's disease exhibit phenotypic changes characteristic of cells re-entering the cell division cycle. Therefore, in this study, we investigated whether components, known to trigger cellular proliferation and differentiation, upstream of the ras/mitogen-activated kinase pathway, could contribute to the activation of a signal transduction cascade in Alzheimer's disease. We found that proteins implicated in signal transduction from cell surface receptors via the ras pathway, namely Grb2 and SOS-1, were altered in cases of Alzheimer's disease in comparison to age-matched controls. SOS is increased in susceptible pyramidal neurons, while Grb2 shows more subtle alterations in subcellular distribution. Importantly, both SOS-1 and Grb2 show considerable overlap with early cytoskeletal abnormalities suggesting that the alteration in signal transduction molecules is a concurrent, if not preceding, event in the pathogenesis of Alzheimer's disease. Taken together with the cell cycle abnormalities previously reported, these findings suggest that a signal derived from the cell surface contributes to a stimulus for neurons in Alzheimer's disease to re-enter the cell cycle.     

Abnormal expression of the cell cycle regulators P16 and CDK4 in Alzheimer's disease

In this study, we demonstrate that two important regulators of the cell cycle, cyclin-dependent kinase-4 and its inhibitor p16, are increased in the brains of cases of Alzheimer's disease patients compared with age-matched controls. Both proteins are increased in the pyramidal neurons of the hippocampus, including those neurons containing neurofibrillary tangles and granulovacuolar degeneration. As p16 is not normally found in terminally differentiated neurons, it seems paradoxical that it is increased in Alzheimer's disease unless it is responding to increases in cyclin-dependent kinase-4 or other cell cycle regulators. Induction of the latter, a protein that signals re-entry and progression through the cell cycle, may itself be the consequence of alpha response to a growth stimulus. Re-entry into the cell cycle is likely deleterious in terminally differentiated neurons and may contribute to the biochemical abnormalities, such as oxidative stress and hyperphosphorylated tau protein, as well as the neuronal degeneration characteristic of the pathology of Alzheimer's disease.     

Return on Infrastructure, the New ROI

IT executives frequently must be able to communicate IT's value in real economic terms, characterizing how technology infrastructure financially benefits the business relative to the company's financial performance objectives. Traditionally, the approach taken has focused on the capital investment process, with return on investment being the primary metric. However, ROI approaches identify financial results pertaining to a specific project, rather than IT programs as a whole, and can be misleading. A new financial metric, return on infrastructure employed (ROIE), has economic and real practical meaning to senior executive management because it recognizes IT as both an asset and a service. ROIE is a new financial management tool with which to judge the business contribution of IT as a whole; using it can motivate management behaviors and disciplines that are essential for success in the modern-day information economy.     

High power, high-efficiency 770 nm 2D laser diode array

A two-dimensional (2D) AlGaAs laser diode array is described which operates at a power density of 2 kW/cm², with an overall efficiency of 35% and a slope efficiency of 56%. The wavelength of operation is 770 nm     

Validation of a fully integrated microfluidic array device for influenza A subtype identification and sequencing

Rapid detection and identification of influenza virus is becoming increasingly important in the face of concerns over an influenza pandemic. A fully integrated and self-contained microfluidic device has been developed to rapidly identify influenza A hemagglutinin and neuraminidase subtypes and sequence portions of both genes. The device consists of a DNA microarray with 12 000 features and a microfluidic cartridge that automates the fluidic handling steps required to carry out a genotyping assay for pathogen identification and sequencing. The fully integrated microfluidic device consists of microfluidic pumps, mixers, valves, fluid channels, reagent storage chambers, and DNA microarray silicon chip. Microarray hybridization and subsequent fluidic handling and reactions were performed in this fully automated and miniature device before fluorescent image scanning of the microarray chip. A micromixing technique based on gas bubbling generated by electrochemical micropumps was developed. Low-cost check valves were implemented in the cartridge to prevent cross talk of the stored reagents. The genotyping results showed that the device identified influenza A hemagglutinin and neuraminidase subtypes and sequenced portions of both genes, demonstrating the potential of integrated microfluidic and microarray technology for multiple virus detection. The device provides a cost-effective solution to eliminate labor-intensive and time-consuming fluidic handling steps and allows the detection and identification of influenza virus in a rapid and automated fashion.     

1 kW peak power 808 nm 2-D laser diode array

A 2-D laser array delivering a peak power of 1 kW, with an overall efficiency of 33.4% is described. The operating parameters of this array are a 100- mu s pulse width, a 15-Hz reception rate, a temperature of 16 degrees C, and at the nominal wavelengths of 808 nm. The spectrometer used in the system is an ISA model HR-320 monochromator. In conjunction with the PAR mode 1453 1024-element array, a resolution of 0.6 nm/element is achieved which allows a 61 nm range to be displayed at any one time.<>