Self-esteem stability and depressive symptoms in acute stroke rehabilitation: Methodological and conceptual expansion.

Objectives: Explore the relationship of self-esteem level, self-esteem stability, and other moderating variables with depressive symptoms in acute stroke rehabilitation. Measures: One hundred twenty participants completed measures of state self-esteem, perceived recovery, hospitalization-based hassles, impairment-related distress, and tendency to overgeneralize negative self-connotations of bad events. Self-report of depressive symptoms was collected at admission and on discharge. Four regression analyses explored the relationship of self-esteem level and stability and each of 4 moderating variables (perceived recovery, hassles, impairment-related distress, and overgeneralization) with depressive symptoms at discharge. Results: Analyses indicated significant 3-way interactions in the 4 regression models. In general, individuals with unstable high self-esteem endorsed greater depressive symptoms under conditions of vulnerability (e.g., lower perceived recovery) than did individuals with stable high self-esteem. Under conditions of vulnerability, participants with stable low self-esteem indicated the highest levels of depressive symptoms. Implications: Self-esteem level and stability interact with psychological, environmental, and stroke-specific variables to predict depressive symptoms at discharge from stroke rehabilitation. This suggests the viability of self-esteem stability in exploring depressive symptoms in this setting and the complexity of emotional adjustment early after stroke. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanoscale vibration analysis of embedded multi-layered graphene sheets under various boundary conditions

The present article deals with the vibrational analysis of multi-layered graphene sheets with different boundary conditions amongst sheets. An elastic multiple-plate model is utilized in which the nested plates are coupled with each other through the van der Waals interlayer force. The interaction of van der Waals forces between adjacent and non-adjacent layers and the reaction from the surrounding media are included in the Reissner–Mindlin-type field equations on which the theoretical formulation is based. The set of coupled equations of motion for the multi-layered graphene sheets is then solved by the generalized differential quadrature method. The numerical analysis presented herein provides the possibility of considering various combinations of layerwise boundary conditions in a multi-layered graphene sheet. Based on exact solution, explicit formulas for the frequencies of a double-layered graphene sheet with all edges simply supported are also obtained. The results of the present numerical solution are shown to be in excellent agreement with those of exact solution for simply supported graphene sheets.     

Terrorist targeting and energy security

Sudden, short-term disruptions seriously endangering energy security can be triggered by a variety of events—among them attacks by terrorists. This study investigates terrorist attack practices against energy infrastructures and discusses how we may understand them. Our results indicate that attacks against energy infrastructures are comparatively few. Also, we find no strong connection between the ideologies of various terrorist groups and their proclivity to attack. In addition, the highly disproportionate number of attacks in a handful of countries highlights the strong geographic concentration of attacks. To explain these findings, we analyze terrorist targeting incentives including intimidation levels, symbolism, attack feasibility, and concerns for stakeholders. We argue that terrorists in general have comparatively few incentives to attack energy supply infrastructures based on our assessment of these factors. Moreover, higher levels of terrorist incidents in states more prone to internal violent conflict may suggest stronger incentives to attack energy infrastructures. When outlining energy security policies, the low frequency of worldwide attacks coupled with the high concentration of attacks in certain unstable countries should be taken into consideration. Energy importing countries could benefit from developing strategies to increase stability in key energy supply and/or transit countries facing risks of internal instability.     

Awareness of faces is modulated by their emotional meaning.

A central question in perception is how stimuli are selected for access to awareness. This study investigated the impact of emotional meaning on detection of faces using the attention blink paradigm. Experiment 1 showed that fearful faces were detected more frequently than neutral faces, and Experiment 2 revealed preferential detection of fearful faces compared with happy faces. To rule out image artifacts as a cause for these results, Experiment 3 manipulated the emotional meaning of neutral faces through fear conditioning and showed a selective increase in detection of conditioned faces. These results extend previous reports of preferential detection of emotional words or schematic objects and suggest that fear conditioning can modulate detection of formerly neutral stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of perceptual load on attention-induced motion blindness: The efficiency of selective inhibition.

Recent visual marking studies have shown that the carry-over of distractor inhibition can impair the ability of singletons to capture attention if the singleton and distractors share features. The current study extends this finding to first-order motion targets and distractors, clearly separated in time by a visual cue (the letter X). Target motion discrimination was significantly impaired, a result attributed to the carry-over of distractor inhibition. Increasing the difficulty of cue detection increased the motion target impairment, as distractor inhibition is thought to increase under demanding (high load) conditions in order to maximize selection efficiency. The apparent conflict with studies reporting reduced distractor inhibition under high load conditions was resolved by distinguishing between the effects of "cognitive" and "perceptual" load. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A microfluidic platform using molecular beacon-based temperature calibration for thermal dehybridization of surface-bound DNA

This work presents a simple microfluidic device with an integrated thin-film heater for studies of DNA hybridization kinetics and double-stranded DNA melting temperature measurements. The heating characteristics of the device were evaluated with a novel, noninvasive indirect technique using molecular beacons as temperature probes inside reaction chambers. This is the first microfluidic device in which thermal dehybridization of surface-bound oligonucleotides was performed for measurement of double-stranded DNA melting temperatures with +/- 1 degrees C precision. Surface modification and oligonucleotide immobilization were performed by continuously flowing reagents through the microchannels. The resulting reproducibility of oligonucleotide surface densities, at 9% RSD, was better than for the same modification chemistries on glass slides in unstirred reagent solutions (RSD=20%). Moreover, the surface density of immobilized DNA probe molecules could be varied controllably by changing the concentration of the reagent solution used for immobilization. Thus, excellent control of surface characteristics was made possible, something which is often difficult to achieve with larger devices. Solid-phase hybridization reactions, a fundamental aspect of microarray technologies often taking several hours in conventional systems, were reduced to minutes in this device. It was also possible to determine forward rate constants for hybridization, k. These varied from 820,000 to 72,000 M(-1) s(-1), decreasing as surface densities increased. Surface densities could therefore be optimized to obtain rapid hybridization using such an approach. Taken together, this combined microfluidic/small-volume heating approach represents a powerful tool for surface-based DNA analysis.     

High-fidelity bilateral teleoperation systems and the effect of multimodal haptics.

In master-slave teleoperation applications that deal with a delicate and sensitive environment, it is important to provide haptic feedback of slave/environment interactions to the user's hand as it improves task performance and teleoperation transparency (fidelity), which is the extent of telepresence of the remote environment available to the user through the master-slave system. For haptic teleoperation, in addition to a haptics-capable master interface, often one or more force sensors are also used, which warrant new bilateral control architectures while increasing the cost and the complexity of the teleoperation system. In this paper, we investigate the added benefits of using force sensors that measure hand/master and slave/environment interactions and of utilizing local feedback loops on the teleoperation transparency. We compare the two-channel and the four-channel bilateral control systems in terms of stability and transparency, and study the stability and performance robustness of the four-channel method against nonidealities that arise during bilateral control implementation, which include master-slave communication latency and changes in the environment dynamics. The next issue addressed in the paper deals with the case where the master interface is not haptics capable, but the slave is equipped with a force sensor. In the context of robotics-assisted soft-tissue surgical applications, we explore through human factors experiments whether slave/environment force measurements can be of any help with regard to improving task performance. The last problem we study is whether slave/environment force information, with and without haptic capability in the master interface, can help improve outcomes under degraded visual conditions.     

Analysis of fair rate calculations in resilient packet ring aggressive mode

Resilient packet ring (RPR) standardized as IEEE 802.17 is a new medium access control (MAC) protocol for metro-ring networks. RPR supports spatial reuse which increases the achieved throughput but it can also result in congestion and starvation of nodes on the ring. Therefore, it is necessary to employ mechanisms to enforce a fair allocation of the ring bandwidth in RPR. In order to maintain fairness among nodes, a fairness algorithm is deployed at each RPR node. When a node detects congestion, it calculates a fair rate which is advertised to all upstream nodes contributing to congestion. Upon receiving the fair rate, the upstream nodes limit the rate of their injected traffic to the advertised fair rate. Consequently, the congested node can utilize the unused capacity and add its local traffic to the ring. In this paper, we develop an analytical model for fair rate calculation in the RPR aggressive mode fairness algorithm in the parking-lot scenario. This model provides an insight on dynamics of the RPR fairness algorithm and can be used to evaluate its performance. We investigate this problem in two cases. First, we assume that the link propagation delay is zero and derive the fair rate equations for this ideal case. We then consider the link propagation delay and develop a more realistic model. We verify the accuracy of our model by simulation results. Furthermore, we use the developed model to study the impact of various parameters on convergence of the fair rate.