The optical (free-carrier) absorption of a hole-electron plasma in silicon

The near-IR absorption of a heavily injected silicon p-i-n diode has been measured. This is thought to be the first comprehensive measurement of the free-carrier absorption of a hole-electron plasma, and it behaves as expected with temperature, injection level and wavelength.

However, the absolute value of the absorption is higher than can be accounted for by ionized impurity scattering mechanisms by a factor of about 2.     

Verbal encoding effects on the visual short-term memory of learning disabled and normal readers.

Investigated the hypothesis that reading difficulties of learning disabled children are attributable to deficiencies in verbal encoding. Adopting a probe-type serial memory task, 60 normal and learning disabled readers matched on CA (9 yrs old), IQ, and sex were compared on recall performance after pretraining of named and unnamed stimulus conditions. The named condition for normal readers was superior in terms of recall performance. Consistent with the findings of F. Vellutino et al (1972, 1973, 1975), no difference was found in recall of nonverbal stimuli between normal and learning disabled readers. These data suggest that primary reading deficits in learning disabled children are related to verbal encoding deficiencies (visual–verbal integration) and not to deficiencies of visual memory, as suggested by the perceptual deficit hypothesis. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Absence of tonic electromyographic activity during sleep in normal and spastic nonmimetic skeletal muscles in man

An electromyographic study of nonmimetic skeletal muscles was carried out in 8 normal adults and 4 patients with spastic hemiparesis during all stages of sleep for a total of 21 nights. All normal subjects showed absence of tonic electromyographic activity in all nonmimetic skeletal muscles in all stages of sleep. Also, during quiet, relaxed wakefulness, tonic muscle discharges disappeared in the normal subjects. Three patients with upper motor neuron spasticity demonstrated results during sleep similar to those obtained in the normal subjects. In the fourth patient, tonic muscle discharges persisted into stage 2 non-REM sleep, disappeared within 30 to 240 seconds following the onset of stage 2 sleep, and were absent during stages 3 and 4 sleep and REM sleep.     

Layered double hydroxide platelets exfoliation into a water‐based polyester

Nitrate layered double hydroxide (LDH) phase Zn₂Al(OH)₆(NO₃)·2H₂O is successfully exfoliated in the presence of polyester under mild conditions using water as essential solvent and at room temperature under air. From small angle X‐ray scattering spectroscopy a total exfoliation is found to be achieved using up to 10 wt % LDH, while intercalated polymer nanocomposite structures largely extended up to 14 nm are observed for loading ranging from 10 to 20 wt %. The process is found to be explained by the diffusion of the polymer chain into the interlayer host structure. Starting from an initial value of 0.89 nm, ≈3, 7, 10, 14, and 20 nm transient interleaved nanostructures are formed without any carbonate uptake. The collective gap distance is certainly due to a defined number of polymer chains diffusing into the LDH interstices. Similarly, starting from an aqueous polyester solution highly concentrated in LDH nitrate phase up to 50% w.w, successive dilutions yield platelet exfoliation, thus rendering a smooth chemistry process attractive for potential applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preferential interactions of fluorescent probe Prodan with cholesterol

The fluorescent probe Prodan has been widely used as a probe of model and biological membranes. Its fluorescent maxima in phospholipid bilayers vary as a function of phase state, with maxima at 485 for the liquid crystal Lalpha, 435 nm for the gel L'beta, and 507 nm for the interdigitated gel LbetaI phase, with excitation at 359 nm. These spectral changes have been used for the detection of phase changes among these phases. In the present study, the fluorescent properties and partition coefficients of Prodan in model membranes of phosphatidylcholines and phosphatidylethanols have been studied as a function of lipid phase state and cholesterol content. It is shown that the Prodan spectrum in the presence of cholesterol no longer reflects the known phase state of the lipid; in each phase state, the presence of cholesterol leads to a spectrum with the maximum at 435 nm, characteristic of the noninterdigitated gel phase. The partition coefficient of Prodan into these lipids also varies with the phase state, giving values of 0.35 x 10(4) in the interdigitated gel, 1.8 x 10(4) in the noninterdigitated gel, and 7. 6 x 10(4) in the liquid crystal phase. In the presence of cholesterol these partition coefficients are increased to 13 x 10(4) for the liquid crystal and the gel phase, and 5.1 x 10(4) in the presence of 100 mg/ml ethanol. These results suggest that Prodan has preferential interactions with cholesterol, and is thus not a randomly distributed fluorescent reporter probe in membranes containing cholesterol. These results suggest that Prodan should be used only with great caution in complex lipid mixtures, particularly biological membranes.     

Authoritative parenting and college students' academic adjustment and success.

This study examined connections between college students' adjustment and success and characteristics of their relationships with their parents. A sample of 236 students completed the Student Attitudes and Perceptions Survey, a 135-item anonymous self-report instrument. Students' grades, confidence level, persistence, task involvement, and rapport with their teachers were generally predicted by both current and childhood levels of parental autonomy granting, demandingness, and supportiveness. Ratings of parenting characteristics were equally predictive of adjustment and success among students living with their parents and those living on their own. They were somewhat less predictive of seniors' adjustment and success than they were for freshmen, sophomores, and juniors. These findings suggest that parenting style continues to play an important role in the academic lives of college students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heterodyne Spatial Tracking System for Optical Space Communication

Design considerations for an optical spatial tracking system for both coherent and noncoherent heterodyne detection are addressed. Heterodyne detection systems are much less susceptible to background radiation and device noise than conventional direct detection systems. In addition, the angle discriminator profile in a heterodyne detection system can be tailored via the local oscillator spatial distribution. An optimal LO distribution is described and its performance is compared to some Suboptimal distributions. It is shown that an ideal quadrant detector can achieve near optimal performance, since the LO effectively acts like a continuum of detectors. Cramer-Rao tracking bounds and other performance criteria are given under the conservative assumption that the angular process to be tracked is a single-pole process. The method used is directly applicable to other types of angular processes. Experimental verification of some of the basic concepts is presented.