Second-harmonic generation in optically trapped nonlinear particles with pulsed lasers

Pulsed lasers are used for simultaneous single-beam three-dimensional optical trapping of and second-harmonic generation in 50-100-nm nonlinear particles. The emission power of the frequency-doubled light, the trapping stability, and the particle degradation are investigated for KTP and LiNbO(3) particles trapped by 25-kHz-repetition-rate Q-switched Nd:YAG and 76-MHz mode-locked Ti:sapphire l a s e r s . Typically 1 pW-10 nW of frequency-doubled light is detected from stably trapped particles. The particles may be used as probes for nonintrusively scanned near-field optical microscopy.     

Analysis and synthesis of a high-speed pneumatic machine drive

The paper deals with the problem of increasing the velocity of actuating elements in a pneumatic machine drive. A rational structure of the drive is chosen by a comparative analysis of the dynamic characteristics of different drives. A dynamic analysis by computer of the most promising drive with different parameters is given. As a result the most important design parameters are established. The dynamic synthesis of this drive is made on the basis of reference data generated by the computer using a limited variation of essential parameters. The maximal piston velocity received at limited size and weight of the drive was taken as an optimal criterion. Accordingly, for this method, design parameters of the drive were chosen for which velocity is much higher than for common drives.     

Thermodynamic assessment of the Fe-Zn system

The Fe-Zn binary system is assessed thermodynamically. A two-sublattice model is adopted to describe the intermetallic compounds, which are treated as nonstoichiometric. A set of parameters consistent with most of the available experimental data on both phase diagram and activities measurements is obtained through optimization. A comparison with previous work is also presented.     

A semi-empirical model for electric defrosting of a cylindrical coil cooler

Frost growth on cooling surfaces held at subfreezing temperatures has been shown to cause degradation of the heat transfer performance of the cooler. Despite the initial increase in the heat transfer rate due to the temporary increase in the heat transfer area, periodic frost removal is necessary. This paper presents a model for defrosting a cylindrical coil cooler employing the electric defrosting method. © 1998 John Wiley & Sons, Ltd.     

Bio-psycho-social consequences of migration stress: a multidimensional approach

In presurgical evaluation of epilepsy, unilateral cerebral inactivation by means of intracarotid injection of amobarbital is used for the determination of cerebral dominance for language and memory functions. This intracarotid amobarbital test (IAT) is intended to yield prognoses concerning postsurgical neuropsychological and neurological deficits. In the present review, neuroradiological and neuropsychological aspects of the procedure are discussed. Each IAT is preceded by a cerebral angiography to exclude or detect vascular anomalies that might be relevant to the interpretation of neuropsychological test data. The main methodological problems of the IAT are interference of various cognitive deficits and monitoring of the course of amobarbital action. Alternative procedures of determination of hemispheric asymmetries--positron emission tomography, electrical stimulation mapping, and noninvasive methods like tachistoscopy--mainly yield data complementary to the results of the IAT and hence are not taken as substitutes of that technique.     

Odour recognition and segmentation by a model olfactory bulb and cortex

We present a model of an olfactory system that performs odour segmentation. Based on the anatomy and physiology of natural olfactory systems, it consists of a pair of coupled modules, bulb and cortex. The bulb encodes the odour inputs as oscillating patterns. The cortex functions as an associative memory: when the input from the bulb matches a pattern stored in the connections between its units, the cortical units resonate in an oscillatory pattern characteristic of that odour. Further circuitry transforms this oscillatory signal to a slowly varying feedback to the bulb. This feedback implements olfactory segmentation by suppressing the bulbar response to the pre-existing odour, thereby allowing subsequent odours to be singled out for recognition.     

Vaporization of (SN)x and TTF-TCNQ

The vaporization of (SN)x was studied by electron impact and chemical ionization mass spectrometry. Comparison of the spectra with those of S₄N₄ suggests that vaporization generates an unstable, acyclic S₄N₄ which subsequently fragments to a cyclic S₃N₃⁺ and SN⁺ ion in the mass spectrometer. Mass spectrometry may be used to analyze (SN)x for S₈ and cage S₄N₄. Vaporization of TTF-TCNQ produced the component donor and acceptor molecules.     

Renal vein thrombosis in a newborn: a case report with emphasis on pathological and radiological features

A case of renal vein thrombosis in a newborn is presented. Trauma during pregnancy is suggested as an etiological factor. In contradistinction to most cases reported the newborn showed no signs of acute illness except for a palpable abdominal mass. Therefore, surgical intervention was delayed for 10 months but this did not impair the infant's growth and well-being.