Determination of band offsets in heterostructured colloidal nanorods using scanning tunneling spectroscopy

The ability to tailor the properties of semiconductor nanocrystals through creating core/shell heterostructures is the cornerstone for their diverse application in nanotechnology. The band-offsets between the heterostructure components are determining parameters for their optoelectronic properties, dictating for example the degree of charge-carrier separation and localization. So far, however, no method was reported for direct measurement of these factors in colloidal nanocrystals and only indirect information could be derived from optical measurements. Here we demonstrate that scanning tunneling spectroscopy along with theoretical modeling can be used to determine band-offsets in such nanostructures. Applying this approach to CdSe/CdS quantum-dot/nanorod core/shell nanocrystals portrays its type I band structure where both the hole and electron ground state are localized in the CdSe core, in contrast to previous reports which predicted electron delocalization. The generality of the approach is further demonstrated in ZnSe/CdS nanocrystals where their type II band alignment, leading to electron-hole separation, is manifested.     

Exhumed Geogrid-Reinforced Retaining Wall

An instrumented geogrid-reinforced wall constructed on a highly compressible foundation was deconstructed 16 months after its completion, providing a unique opportunity to exhume and examine the instrumented geogrids that were used to construct the wall. The objectives of this post mortem study were: (1) to inspect the condition of the strain gauges that were attached to the geogrid layers before construction and to verify the reliability of their output; (2) to develop a procedure in which the residual (plastic) strains along exhumed geogrid panels could be determined; and (3) to assess the in situ strain and force distribution along geogrid panels based on the measured residual strains from the exhumed geogrids. After exhumation, it was observed that many of the attached strain gauges failed due to full or partial debonding from the geogrid, thus rendering outputs which potentially underestimated the actual strain. Combining aperture measurements of virgin and exhumed geogrids, all from the same manufacturing lots, enabled the assessment of residual strains following stress relaxation. Laboratory simulation of loading and unloading, including creep and relaxation, yielded a relationship between the measured residual strains and the in situ strain and force distribution; i.e., the residual strain fingerprint provided insight into the behavior of the geogrids within the wall prior to its deconstruction. The mobilized maximum tensile strains in the geogrid panels along the height of the wall were roughly uniform, in the range 4±1%. These findings imply that if the same type of reinforcement had been used throughout the height of the wall, the mobilized force along the height would have been relatively uniform. The back-calculated maximum force in the geogrids indicated that the factor of safety on the long-term strengths of the geogrids ranged from about 1.4 on the stronger/stiffer geogrid to about 1.8 on the weaker/softer geogrid.     

A Smart Sensor System for Carbon Monoxide Detection

This paper illustrates a smart sensor system for carbonmonoxide detection. An innovative technological approach hasbeen pursued to fabricate gas sensors on silicon substrate, compatiblewith IC fabrication. A mixed analog-digital electronic interfaceprocesses the outputs of three sensors to compensate relativehumidity and interfering gases. Sigma-delta signal processingand low-frequency noise reduction techniques are used to minimizesilicon area and to meet the required performance in a standardCMOS technology.     

Seasickness as a self-fulfilling prophecy: Raising self-efficacy to boost performance at sea.

Applying the self-fulfilling prophecy (SFP) approach to combating seasickness, the authors experimentally augmented the self-efficacy of naval cadets by telling them that they were unlikely to experience seasickness and that, if they did, it was unlikely to affect their performance at sea. Naval cadets (N?=?25) in the Israel Defense Forces were randomly assigned to experimental and control conditions. At the end of a 5-day training cruise, experimental cadets reported less seasickness and were rated as better performers by naive training officers than were the control cadets. There was a nonsignificant tendency for the experimental effects to be stronger among cadets of lower initial self-efficacy, suggestive of behavioral plasticity. Reducing seasickness by verbally enhancing self-efficacy is discussed as an application of "verbal placebo." These findings extend the generalizability of the SFP-at-work model and suggest new arenas for its practical application. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Empathy and ego development": Correction.

Reports an error in the original article by A. F. Carlozzi et al (Journal of Counseling Psychology, 1983[Jan], Vol 30[1], 113-116). A sentence was omitted on page 115. The missing sentence is provided. (The following abstract of this article originally appeared in record 1983-10448-001.) Examined the relationship between empathy and ego development to determine whether, as J. Loevinger (1976) suggested, empathy is characteristic of higher levels of ego development. 51 undergraduates (dormitory advisors) completed the Affective Sensitivity Scale (a measure of empathy) and the Loevinger Sentence Completion Test (a measure of ego development). Analysis of test scores indicated that Ss at higher levels of ego development (I-3/4 and above) had significantly higher empathy scores than did those at lower ego levels. Findings have implications for the selection and training of individuals to serve in counseling or quasi-counseling roles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-efficacy training to speed reemployment: Helping people to help themselves.

Assessed the impact of training designed to boost general self-efficacy (GSE) on job-search activity and on reemployment among 66 persons unemployed for up to 18 wks. Randomly assigned experimental participants attended 8 behavioral-modeling workshop sessions over 2.5 wks. The manipulation check showed that training boosted GSE as intended. The workshop also increased job-search activity, confirming the hypothesis that raising GSE motivates intensification of effort. The treatment increased reemployment among participants low in initial GSE but not among those with high GSE. The greater plasticity of individuals low in GSE suggests that the practical utility of training is moderated by initial GSE. It is concluded that individuals of low GSE should be given priority access to scarce behavioral-modeling training resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time-limited and band-limited environment: Signals and systems

Of concern is an environment made up of signals and systems tightly confined both in time and frequency. Such an environment is often encountered in transmission line circuits, radar, sonar, and optical circuits, and when the principal signals are well-defined sharp pulses. It will be seen that once this environment is achieved, the signals and systems possess some attractive properties. A conventional system may preserve the symmetry of a propagating signal or change its symmetry from even to odd or from odd to even. Another system may be used to predict the arrival of an incoming pulse with a high degree of accuracy. Electrical networks may also be associated with these properties. Approximation problems, existence theorems, and realization schemes will be addressed and developed.     

Impulse stress wave propagation in elongated bodies: Apparent deviations from circuit realizability principles

Of concern is the undistorted propagation of pulse stress waves in long thin bodies. The primary signals are arbitrarily sharp pulses projected along thex-axis. It will be seen that these pulses travel close to the speed of sound in unbounded media. Secondary pulses follow representing interactive disturbances traveling along they-axis. But the process brings out certain anomalies in circuit realizability requirements. These issues, transmission parameters, and coupling between the various signals are studied in detail. The results are supported by experiments.Work supported by TecSonics Inc., Twinsburg Ohio.