Allergic fungal sinusitis in the southeastern USA: involvement of a new agent Epicoccum nigrum Ehrenb. ex Schlecht. 1824

The purpose of this study is to find the correlation between middle latency auditory evoked potentials (MLAEP) and sound activated single photon emission computed tomography (SPECT) studies. This study was performed on six normal right-handed volunteers with a mean age of 35.2 +/- 7.6 years, using the split-dose technique. First, a SPECT study was performed on subjects in blinded, awake and silent states. After bilateral ears were stimulated with a click sound, MLAEP and a second SPECT study were performed. Subtraction of the first SPECT from the second SPECT revealed a statistically significant increase of cerebral blood flow (CBF) in the bilateral superior temporal region. Bilateral Na amplitudes of MLAEP had a statistically significant and good correlation with the percentages of CBF changes in the bilateral superior temporal region. The superior temporal cerebral blood flow activation can be expressed by electrophysiological activation. Moreover, correlation during the left Na components and left frontal and occipital lobe are discussed.     

An automated microwave measurements experience for undergraduates

Experiments in microwave measurements for an undergraduate laboratory course are described that bridge the gap between point-by-point manual measurements and automatic network analyzer measurements. In the sequence of 10 laboratory experiments, the basic parameters of frequency versus wavelength in a waveguide are explored, first in point-by-point measurements versus frequency. Swept frequency measurements are taken up next in the form of an open-ended design experiment investigating a simple two-pole band pass filter. Following this, scalar transmission and reflection measurements are made using a PC as a controller and data-acquisition unit. Lastly, the Hewlett-Packard 8510B Automatic Network Analyzer is used by the students to perform the measurements on the same device as a verification of the earlier results. This paper concentrates on the design of the computer-aided measurements experiment, describing the requirements for the experimental content as well as the peripheral content, such as the controller language (HP BASIC) and the interface (HPIB-HP Interface Bus)     

Category learning deficits in Parkinson's disease.

Sixteen patients with Parkinson's disease (PD), 15 older controls (OCs), and 109 younger controls (YCs) were compared in 2 category-learning tasks. Participants attempted to assign colored geometric figures to 1 of 2 categories. In rule-based tasks, category membership was defined by an explicit rule that was easy to verbalize, whereas in information-integration tasks, there was no salient verbal rule and accuracy was maximized only if information from 3 stimulus components was integrated at some predecisional stage. The YCs performed the best on both tasks. The PD patients were highly impaired compared with the OCs, in the rule-based categorization task but were not different from the OCs in the information-integration task. These results support the hypothesis that learning in these 2 tasks is mediated by functionally separate systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of microcavity VCSEL lasing modes using a full-vectorweighted index method

Presents a semi-analytic full-vector method for calculating the spatial profile, optical confinement factor resonant frequency, absorption loss, and mirror loss of lasing modes in cylindrically symmetric microcavity vertical-cavity surface-emitting lasers (VCSEL's). It can be shown that this method gives the best separable approximation for the electric and magnetic vector potentials. Our technique can model the entire VCSEL structure and can treat complex media. We apply the method to etched-post and oxide-apertured VCSEL's designed for 980-nm emission and find a blueshift in cavity resonance as the cavity radius shrinks. We also find a minimum optical cavity radius below which radially bound lasing modes cannot be supported. This radius depends on the device geometry and lies between 0.5 and 1 μm for the devices studied. Once this model is augmented to include diffraction losses-the dominant loss mechanism for conventional small aperture lasers-it will provide a complete picture of lasing eigenmodes in microcavity VCSEL's     

Novel, wide bandwidth, micromachined ultrasonic transducers

Surface micromachined, capacitive ultrasonic transducers have been fabricated using a low thermal budget, CMOS-compatible process. This process allows inherent control of parameters such as membrane size and thickness, cavity size and the intrinsic stress in the membrane to be achieved. Devices fabricated using this process exhibit interesting properties for transduction in air at frequencies in excess of 1 MHz when driven from a standard ultrasonic voltage source. Experiments have been performed with devices containing silicon nitride membranes of variable thicknesses over a 2 μm thick air cavity and with device dimensions of up to 5 mm square. This is much larger than has been reported for a device with a single membrane. Calibration measurements using 1/8 inch microphones in air, and miniature PVDF hyrdophones in water, have been performed. The dependence on d.c. bias voltage is examined, involving static membrane deflection measurements and received peak voltages. Pulse-echo and pitch-catch mode operation have been achieved. Interferometric measurements of membrane displacement have been performed in air to illustrate the membrane deflection characteristics. Operation in liquids is also discussed     

Small-geometry, high-performance, Si-Si1-xGexheterojunction bipolar transistors

Si-Si_1-xGe_x heterojunction bipolar transistors (HBTs) with very heavily doped bases, fabricated using electron-beam lithography to obtain very small feature sizes, are discussed. Emitter, base, and collector epitaxial layers were grown in situ in a lamp-heated, chemical-vapor-deposition reactor. Transistors with common-emitter current gain of approximately 50 and f_t of about 28 GHz have been obtained. Analysis indicates that the frequency response is limited by parasitic resistances and capacitances in the simple demonstration structure used, rather than by the intrinsic device characteristics. Simple ring oscillators have been fabricated using HBTs in the inverse-active mode of operation