A double-recessed Al0.24GaAs/In0.16GaAspseudomorphic HEMT for Ka- and 𝒬-band power applications

A double-recessed 0.2-μm-gate-length pseudomorphic HEMT (PHEMT) has been demonstrated with 500 mW of output power (833 mW/mm of gate periphery), 6-dB gain, and 35% power-added efficiency (PAE) at 32 GHz. At 44 GHz, the device exhibited 494 mW of output power (823 mW/mm), 4.3-dB gain, and 30% PAE. This level of performance is attributed to excellent MBE material, optimized epitaxial layer design, and the use of individual source vias and of double recess with tight channel dimensions. Excellent 3-in-wafer uniformity was also observed: DC yield was greater than 95% and the interquartile range for all DC parameters was less than 20% of the median value (most are significantly lower)     

Human influenza virus A/HongKong/156/97 (H5N1) infection

Introduction of influenza viruses with gene segments of avian origin into the human population may result in the emergence of new pathogenic human influenza viruses. The recent infection of a 3-year-old boy with an influenza A (H5N1) virus of avian origin can be considered as an example of such an event. However, this virus, influenza A/Hong Kong/156/97 (H5N1) and the 17 additional H5N1 viruses isolated from humans by the end of 1997 lack the ability to spread efficiently amongst humans and therefore have limited pandemic potential. However, the possibility of reassortment of these viruses with currently circulating human viruses illustrates the need for pandemic preparedness.     

Patterns of neuropsychological impairment in mild dementia: a comparison between Alzheimer''s disease and multi-infarct dementia

Left ventricular wall motion abnormalities secondary to stress-induced myocardial ischemia can be detected with difficulty by mentally comparing echocardiographic images sequentially recorded on videotape. Digital stress-echocardiography, a combination of ultrasound imaging and digital archiving technologies, at least partially can overcome this problem: the technique is based on reviewing images at rest and after stress (exercise or pharmacological) side by side in dual- or quad-screen digital format, in a synchronized cine-loop, as if obtained simultaneously. This technique however is presently not widely used, due to the high cost of most commercially available systems. We have developed a digital stress-echo system, which is easy to use and relatively inexpensive, running on a Macintosh II personal computer with 8-bit graphics. The 2-D echocardiographic images recorded on videotape are digitized offline using a video digitizing board. The image can be displayed and analyzed using the public domain NIH image software developed by Wayne Rasband, without loss in image quality and resolution, particularly if using Super-VHS videotape. We have made a macro procedure for the montage in a quad-screen format of four digital recorded echocardiographic cardiac cycles of six frames that takes only a little more time than commercially available systems. In conclusion, the use of a personal computer and low-cost software may help to make digital stress-echo techniques more widely feasible in the clinical setting and increase the diagnostic power of the ultrasound technique in the evaluation of patients with known or suspected coronary artery disease.