The use of a quantitative differential mode delay technique to improve fiber bandwidth

Three iterations of a simple quantitative differential mode delay (DMD) technique increased the bandwidth of multimode graded-index fibers at 1300 nm from an average of 530 MHz, km to an average of 1417 MHz . km. The bandwidth at other wavelengths showed a commensurate increase.     

A specialized doctoral program in health psychology: Considerations in its evolution.

The Graduate Group in Psychology at the University of California, San Francisco, began in 1970 to develop a specialized program in health psychology. A dual emphasis on both operational and theoretical value from the research shaped a curriculum that stresses basic courses in social, personality, and cognitive psychology; research methodology; and introductions to the health system and biomedical science. Responses from health care settings to the program have been positive. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Field independence and perceptions of task characteristics: A laboratory investigation.

In 2 consecutive laboratory studies using virtually identical methods, undergraduate Ss (45 and 133 Ss for Studies 1 and 2, respectively) completed the Group Embedded Figures Test in group sessions. They then performed an assembly task in a laboratory setting and completed a measure designed to assess the "immediate" and "projected" perceptions of task characteristics. Results of Study 1 show significant correlations between field independence and immediate perceptions of variety, task identity, and feedback. These results were replicated in Study 2. In addition, Study 2 revealed significant correlations between field independence and (a) immediate perceptions of interaction and (b) projected perceptions of variety and interaction. Results suggest that field independence may be a determinant of individuals' perceptions of task characteristics. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of an acute increase in renal perfusion pressure on sodium transport in the rat kidney

Twenty-two young adult patients with femoral-neck fractures fitting the following criteria were evaluated. All patients (1) were between twenty and forty years old, (2) had clinical and follow-up roentgenograms at least twelve months after the injury, (3) incurred fracture of the neck of the femur through normal bone, and (4) did not incur a stress fracture. The incidence of non-union was 59 per cent (thirteen of twenty-two patients) and of avascular necrosis, 86 per cent (nineteen of twenty-two patients). Evaluation of patients and results are discussed.     

Partial-discharge-inception testing on low-voltage motors

This is a review of one manufacturer's efforts toward testing National Electrical Manufacturers Association (NEMA) low-voltage motor insulation for compatibility with adjustable-speed drives (ASDs). Partial-discharge-inception-voltage (PDIV) measurements were selected as a tool to evaluate the future performance of the stator insulation system to resist deterioration by the drives. PDIV measurement is explained in terms of procedure and accuracy. Data are presented from tests made on motors from several prominent manufacturers.     

Anaesthesia of the tympanic membrane using iontophoresis

Experience is described of the use of iontophoresis of 2% lignocaine to achieve effective tympanic membrane anaesthesia. The main uses are for outpatient myringotomy and transtympanic electrocochleography. Complete anaesthesia of the drum has been obtained in all cases, and those patients who had previously had these procedures carried out without anaesthetic, or with surface 'anaesthesia' only, all stated a marked preference for iontophoresis. No complications have occurred.     

1.2 Gb/s closely-spaced FDMA-FSK direct-detection star network

For the frequency-division-multiple-access-frequency-shift-keying (FDMA-FSK) network, the FSK signal is converted to amplitude-shift-keyed (ASK) format by a tunable fiber Fabry-Perot (FFP) filter that acts simultaneously as a demodulator and demultiplexer. Frequency-tunable two-electrode distributed-feedback (DFB) laser transmitters produce distorted FSK spectra due to nonuniform FM response for modulation frequencies above ~200 Mb/s. The frequency-domain properties of the laser are related directly to the time-domain properties of the transmitted data stream. The critical dependence on the FFP passband width and center frequency location for undistorted signal recovery is shown. By optimizing these parameters, the data transmission rate can be increased while keeping the power penalty due to signal distortion below 1 dB     

Mid-infrared gas sensing using a photonic bandgap fiber

We demonstrate methane sensing based on Fourier transform infrared spectroscopy using a hollow-core photonic bandgap fiber guiding in the mid-infrared and idler pulses from a femtosecond optical parametric oscillator. Transmission measurements are presented for several fibers, and sensing is demonstrated using a fiber whose bandgap overlaps the methane fundamental absorption lines. The gas filling process of the air core is described, and qualitative methane concentrations measurements to 1000 ppm (parts in 10(6)) are reported. Operation down to 50 ppm based on our current experiment is predicted.     

Cephalopod coloration model. I. Squid chromatophores and iridophores

We have developed a mathematical model of skin coloration in cephalopods, a class of aquatic animals. Cephalopods utilize neurological and physiological control of various skin components to achieve active camouflage and communication. Specific physical processes of this coloration are identified and modeled, utilizing available biological materials data, to simulate active spectral changes in pigment-bearing organs and structural iridescent cells. Excellent agreement with in vitro measurements of squid skin is obtained. A detailed understanding of the physical principles underlying cephalopod coloration is expected to yield insights into the behavioral ecology of these animals.     

Magnitude estimation and categorical rating scaling in social sciences: a theoretical and psychometric controversy

This paper revisits a half-century long theoretical controversy associated with the use of magnitude estimation scaling (MES) and category rating scaling (CRS) procedures in measurement. The MES procedure in this study involved instructing participants to write a number that matched their impression of difficulty of a test item. Participants were not restricted in the range of numbers they could choose for their scale. They also had the choice of disclosing their individual scale. After the MES task was completed, participants were given a blank copy of the test to rate the perceived difficulty of each item using a researcher-imposed categorical rating scale from 1 (very easy) to 6 (very difficult). The MES and CRS data were both analyzed using Rasch Rating scale model. Additionally, the MES data were examined with Rasch Partial Credit model. Results indicate that knowing each person's scale is associated with smaller errors of measurement.