Measurement of specimen charging in scanning electron microscopy with a kelvin probe

A vibrating Kelvin probe in form of a platinum wire loop is used to measure the surface potential U_s on electron-irradiated free-floating metal and insulator specimens as a function of electron energy E. This allows an accurate measurement of the critical electron energy E₂ for no charging. At energies below E₂, the positive charging increases with decreasing energy to U_s=2–5 eV at E=0.5 keV and switching off the collector bias of the Everhart-Thornley detector. A two-to threefold increase of U_s is observed when the bias is switched on. For E > E₂, the strong increase of a negative surface potential can be measured. Insulating films free-supported on a conductive substrate show a steep decrease to small positive and negative U_s when the film thickness becomes lower than the electron range at a critical energy E₃ > E₂. At insulating specimen the temporal decrease of charging can be measured when the electron beam is switched off.     

DMET: a computer package for the design of digital microwaveline-of-sight communication routes

The computer-aided design software package DMET (Digital Microwave Engineering Tool), which has been developed to meet the needs of the telecommunication engineering community involved in the design of line-of-sight digital microwave communication routes, is described. DMET can be used either by professionals or engineering students in such a way that efforts can be concentrated on the design objectives of the link rather than on cumbersome and tedious computations. This software package is particularly useful as a tool in teaching communication engineering students the basic practical steps involved in the design of line-of-sight radio communication links. Examples of antenna height computation and radio link budget computation using DMET are presented     

Assessing Environmental Risks: Lessons From Superfund

This essay analyzes the use of risk assessment in Superfund, the controversial American hazardous waste cleanup programme. We argue that risk assessment has been used in three ways in discussing policy options in this programme: as a metric for assessing performance; as a means for resolving conflicts; and as a tool for comparing different environmental initiatives. Use of risk reduction as an analytical tool in European efforts to clean up hazardous waste sites is discussed. We conclude that while risk assessment has potential utility for each of these applications, there are also accompanying technical and political difficulties.     

Comparing the motivations of Spanish and Finnish computer personnel with those of the United States

A survey of perceptions of IS personnel – managers, technical specialists and programmer/analysts – was conducted by the Association for Technical Information in Spain, using the JDS/DP, a modification of the job diagnostic survey instrument. Data were collected on fifteen job variables, related to four motivation aspects: job components, satisfaction levels, need for growth/achievement and goal participation/feedback. The results were compared with those of a similar survey for the same job types in Finland. Results were also compared with the norms developed for computer personnel in the USA. The survey revealed that personnel attracted to the computer field have a high need for growth and a low need for social interaction. It also revealed that the work itself was ranked highest among eleven motivating factors. For both Spain and Finland, the technical specialist job had a mis-match between the job's motivating potential and the employee's need for growth, compared with similar personnel in the USA. By examining the core job dimensions, managers can redesign the job to produce a match between these two major components of motivation.     

Keynote paper: Architectures for integrating manufacturing activities and enterprises

This paper is a summary of the major technical report (Williams et al., 1993) of the IFAC/IFIP Task Force on Architectures for Integrating Manufacturing Activities and Enterprises. It presents a synopsis of the investigations of pertinent architectures undertaken, and the findings generated relating to the suitability of various architectures for the integration task. It also presents the Task Force's recommendations for achieving a “complete” architecture in terms of the necessary capabilities by “completing” a currently available architecture. The Task Force also outlined how a “best” architecture could be achieved by selecting and combining the best features of the available architectures.     

Nonlinear electrical transport in K-TCNQ at low temperatures

A remarkable nonlinearity has been observed for electric transport in K-TCNQ (potassium tetracyanoquinodimethane) quasi-one-dimensional conductor. The negative differential resistance region appears afterV _m (turn over voltage), beyond which voltage goes down with increase of current. A possible mechanism is discussed in terms of dynamics of charged solitons and domain walls in one-dimensional molecular stacks of these types of crystals.     

Concordant but different: Cognitive function, cerebral anatomy, and metabolism in monozygotic twins with Alzheimer's disease.

To illustrate the utility of the twin method in Alzheimer's disease (AD) research, a pair of monozygotic twins, concordant for the disease but markedly different in their clinical presentations, was studied in detail. Neuropsychological evaluation, magnetic resonance imaging (MRI), and cerebral glucose metabolic studies revealed a typical behavioral presentation for AD in Twin A. In contrast, Twin B showed prominent visuospatial impairments. Although there was no identified cause for the disparate presentations, a close correspondence was observed between the neuropsychological findings and the regional brain measures. The results suggest that the trajectory of AD may vary widely even in genetically identical individuals. Factors accounting for the variability include potential intrauterine, early developmental, and environmental differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of rotor profiles on the torque of a switched-reluctancemotor

The authors examine effects on the torque that simple variations of the standard rotor pole face profile could have, basically from an elementary viewpoint of how the modified profiles affect the distribution and magnitude of the radial and tangential components of the flux density. It is observed that the average torque is mostly affected by changes that alter the dominant radial component, such as changes in the effective air gap length. The other observation that an increase in the average torque can also be obtained by a favorable shift in the torque versus angle characteristics by relatively simple changes of the rotor pole profile is not so well known. Such a shift that reduces the slope of the torque angle characteristic, skewing the curve towards the unaligned position, has two advantages: one is that the phase inductance is at its maximum positive slop and, hence, the maximum torque, when the phase is energized; second, the flatter inductance profile near the aligned position when the phase current is to be commutated would allow a faster drop off of the commutated current and, thus, a smaller negative torque     

Cable insulation density profile determined from ultrasonicvelocity measurements

Density results obtained on the same cable sample with a column and from ultrasonic measurements are reported. A calibration curve relating ultrasonic velocity and cable insulation density is given for PE and crosslinked PE (XLPE) cables. The limits and advantages of deducing density profiles of cable insulation using a focused, ultrasound beam rather than the more time-consuming column measurements are discussed