Voluntary and professional disaster-workers: similarities and differences in reactions

Forty-three rescuers responding to a bus crash that killed 12 children and 4 adults and injured many more answered questionnaires at 1 and 13 months following the crash. This study compared the responses of the voluntary and professional helpers, using the Impact of Event Scale (IES) and the General Health Questionnaire (GHQ). For all helpers taken together, the decline in IES-intrusion and IES-total scores was significant from 1 to 13 months. The voluntary helpers reported significantly more intrusion and avoidance on the IES at 1 month than professional helpers, and for avoidance the voluntary helpers still evidenced a significantly higher score than professional helpers at 13 months. The GHQ scores at 13 months reflected that the long-term negative impact of the event was low.     

Multipulse operation of a high average power, good beam qualityzig-zag dye laser

A laser pumped zig-zag dye laser operating at 568 nm with a pulse length ~2 μs has been sealed to high power using a MOPA configuration. Pulse energies in excess of 7 J with beam quality <2 XDL have been achieved under repetitively pulsed, 10 Hz operation. RMS jitter was measured as 0.12 of a 1 XDL spot. The device has operated with over 70 W output for runs up to 5 s. Substantially longer run times and output powers are possible. This device represents an advance in dye laser capabilities. Improvement in pointing accuracy of better than an order of magnitude have been demonstrated. In addition, an improvement in beam quality by about an order of magnitude has been achieved compared to other dye lasers operating in this power range     

Electrical characterization of very-narrow-gap bulk HgCdTe single crystals by variable magnetic field hall measurements

Variable-magnetic-field Hall measurements (0 to 1.5 T) are performed on very-narrow-gap bulk-grown Hg_1−xCd_xTe single crystals (0.165 ≤ x ≤ 0.2) at various temperatures (10 to 300K). The electron densities and mobilities are obtained within the one-carrier (electrons) approximation of the reduced-con-ductivity-tensor scheme. The present data together with the selected data set reported by other workers exhibit a pronounced peak when the electron mobility is plotted against the alloy composition x-value which has been predicted to be due to the effective-mass minimum at the bandgap-crossing (E_g ≈ 0). The observed position (x ≈ 0.165), height (≈4 x 10² m²Vs), and width (≈0.01 in x) of the mobility-peak can be explained by a simple simulation involving only ionized-impurity scattering. A lower bound of the effective mass is introduced as a fitting parameter to be consistent with the finiteness of the observed electron mobility and is found to be of the order of 10⁻⁴ of the mass of a free electron.     

On the geometrical material structure of anelasticity

Summary G-structures are the geometric backbone of the theory of material uniformity in continuum mechanics. Within this geometric framework, anelasticity is seen as a result of evolving distributions of inhomogeneity reflected as material nonintegrability. Constitutive principles governing thetime evolution of the G-structure underlying the finite-strain theory of anelasticity (e.g., plasticity) are proposed. The material Eshelby stress tensor is shown to be thedriving force behind this evolution. This should allow for a thermodynamically admissible formulation of anelasticity viewed as a G-structure evolution.     

Rotation at the crack tip under uniform heat flow in an infinite medium

A complex analysis of rigid body rotation is presented. The crack-tip rotation for a line crack subjected to steady uniform heat flow is obtained in terms of thermal stress intensity factor in shear mode of the crack, the material and thermal parameters and coordinates of points close to the crack tip. The shear strip configuration is analysed on the basis of rotation and displacement at the end of the shear strip.     

Effect of beam voltage on the properties of aluminium nitride prepared by ion beam assisted deposition

The effects of nitrogen-beam voltage on the structure, stress, energy band gap and hardness of AIN thin films deposited on Si (111), Si (100) and sapphire (0001) by ion beam assisted deposition (IBAD) are reported. As the nitrogen-beam voltage was increased from 50 to 200 V, the stress and disorder in the AIN films increased as determined by X-ray diffraction, FTIR and Raman spectroscopy. The preferred orientation of the film's c-axis changed from completely normal to the film at 100 V, to a mixture of normal and in the plane of the film at 200 V. For AIN films deposited under the same conditions, the films were more highly oriented on sapphire (0001) than in Si (111). The hardness of the films increased from 18.2 to 23.7 GPa with the nitrogen-beam voltage, and possible reasons for this change in hardness are considered.     

Erbium-doped silicon and porous silicon for optoelectronics

Silicon forms the backbone of the microelectronics industry, and possibly, of the optoelectronics industry, hitherto dominated by III/V materials. One of the remaining goals is to build an optical source in silicon. Erbium exhibits luminescent 1.54 μm intra-4f transitions in both silicon and porous silicon. This paper reviews the work which has been carried out in this field and discusses some possible additional applications of erbium-doped silicon in optoelectronics, such as a novel on-chip temperature sensor.     

Sequential discrete multilevel automated system for recording electron-diffraction patterns

This article considers a discrete sequential multilevel automated system for recording electron-diffraction patterns. A comparative analysis is presented, along with experimental results that make it possible to evaluate the effectiveness of the technical decisions on which the device is based. The general design of the system is presented. Translated from Izmeritel'naya Tekhnika No. 5, pp. 16–18, May, 1996.