Person memory and causal attributions.

Three experiments with 273 college students were conducted to reconcile the apparent contradiction between the well-established finding that initial impressions are resistant to incongruent (ICG) information and the finding that information ICG with an impression is particularly likely to be recalled. Using a procedure similar to that of R. Hastie and P. A. Kumar (1979), a situational or dispositional attribution was provided for a target item, which was either congruent (CG) or ICG with an initial impression. The ICG item was more likely than the CG item to be recalled only when attributed to dispositional causes (Exp I). The congruence of the target had greater impact on impressions when attributed to dispositional causes, particularly when Ss were given little other information about the target (Exps I and II). Exp III revealed that Ss preferred situational attributions for ICG items and dispositional attributions for CG. The authors conclude that Hastie and Kumar's findings may be limited to conditions in which situational attributions for TCG information are not provided. Possible mediators of the effects of causal attributions on recall, and the relation between recall and impressions are discussed. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rising sludge in secondary settlers due to denitrification

High suspended solids concentrations in settler effluents can be caused by rising sludge, which is the effect of flotation of solids by nitrogen gas resulting from biological denitrification. Many factors influence the nitrogen gas bubble evolution. The most important factor is the rate of biological denitrification. Factors like nitrogen gas solubility and oxygen concentration in settler influent only play a minor role. The hydraulic retention time in the bottom part of the settler is, for all practical purposes, so high that sufficient nitrogen gas will be generated at temperatures above 20°C, if the nitrate content in the influent to the settler is above the critical one. For temperatures around 20°C the critical nitrate-nitrogen concentration is 6–8 g NO₃⁻-N/m³. The best measure in order to avoid rising sludge is to denitrify the wastewater in the treatment process ahead of the settler.     

Follow-up outcome in short-term group therapy for complicated grief.

This study investigated 4 types of outcome over a 6-month follow-up period for 84 psychiatric outpatients who had been treated for complicated grief using short-term group therapy. The 4 types differed in regard to whether and when patients achieved clinically significant change on a primary grief outcome variable. Approximately half of the patients achieved clinically significant change by the end of treatment and maintained it over follow-up (maintenance). Another quarter of the patients reported clinically significant change, but only at follow-up (delayed recovery). A few patients achieved clinically significant change at the end of treatment, but not at follow-up (relapse). Finally, nearly a quarter of the patients failed to achieve clinically significant change (nonrecovery). The findings suggest that investigators look beyond the end of treatment when assessing improvement in patients treated with short-term group therapy for complicated grief. Inclusion of delayed recovery patients can substantially modify conclusions about the usefulness of short-term therapies for complicated grief. Delayed recovery patients differed from the other types of patients on greater perceived social support and greater change during the follow-up period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

System fault-tolerance analysis of COTS-based satellite on-board computers

Fault-tolerance analysis reveals possible system behavior under the influence of faults. Such analysis is essential for satellites where faults might be caused by space radiation and autonomous recovery is needed. In this paper we present a statistical simulation approach for fault-tolerance analysis of satellite On-Board Computers (OBCs) that are based on Commercial Off-The-Shelf (COTS) components. Since the logic level of COTS electronics is unknown to satellite designers, a new higher-level fault-tolerance analysis is required. We propose such technique that relies on OBC modeling and fault modeling, based on the modeling principle of Single-Event Upsets (SEUs). For the first time we can compare the efficiency of fault-tolerance techniques implemented in software and Field-Programmable Gate Array (FPGA). In addition, our approach enables to analyze system fault-tolerance at early development stages. In a case study the approach is applied to an OBC with a Microsemi SmartFusion SoC, that executes a satellite attitude control algorithm. The gained statistical simulation results enabled 50% reduction in the hardware overhead of the implemented memory scrubbing technique without loss in fault-tolerance. Our method revealed critical fault-tolerance drawbacks of the initial system design that could have lead to satellite mission failure.     

Asymptotic Bias and Variance of Conventional Bispectrum Estimates for 2-D Signals

In this paper, we derive the asymptotic bias and variance of conventional bispectrum estimates of 2-D signals. Two methods have been selected for the estimation: the first one – the indirect method – is the Fourier Transform of the weighted third order moment, while the second one – the direct method – is the expectation of the Fourier component product. Most of the developments are known for 1-D signals and the first contribution of this paper is the rigorous extension of the results to 2-D signals. The calculation of the bias of the direct method is a totally original contribution. Nevertheless, we did all calculations (bias and variance) for both method in order to be able to compare the results. The second contribution of this paper consists of the comparison of the theoretical bispectrum estimate bias and variance with the measured bias and variance for two 2-D signals. The first studied signal is the output of a non-minimal phase linear system driven by a non-symmetric noise. The second signal is the output of a non-linear system with Gaussian input data. In order to assess the results, we performed the comparison for both methods with different sets of parameters. We show that the maximum bias coefficient is the one of the 1-D case multiplied by the dimensionality of the signal for both methods. We also show that the estimate variance coefficient is the 1-D case coefficient with a power equal to the signal dimensionality.Received October 21, 2002; Revised December 2003; Accepted March 25, 2004; First Online Version published in December 2004     

An overview of the development of the first wall and other principal components of a laser fusion power plant

This paper introduces the JNM Special Issue on the development of a first wall for the reaction chamber in a laser fusion power plant. In this approach to fusion energy a spherical target is injected into a large chamber and heated to fusion burn by an array of lasers. The target emissions are absorbed by the wall and encapsulating blanket, and the resulting heat converted into electricity. The bulk of the energy deposited in the first wall is in the form of X-rays (1.0-100 keV) and ions (0.1-4 MeV). In order to have a practical power plant, the first wall must be resistant to these emissions and suffer virtually no erosion on each shot. A wall candidate based on tungsten armor bonded to a low activation ferritic steel substrate has been chosen as the initial system to be studied. The choice was based on the vast experience with these materials in a nuclear environment and the ability to address most of the key remaining issues with existing facilities. This overview paper is divided into three parts. The first part summarizes the current state of the development of laser fusion energy. The second part introduces the tungsten armored ferritic steel concept, the three critical development issues (thermo-mechanical fatigue, helium retention, and bonding) and the research to address them. Based on progress to date the latter two appear to be resolvable, but the former remains a challenge. Complete details are presented in the companion papers in this JNM Special Issue. The third part discusses other factors that must be considered in the design of the first wall, including compatibility with blanket concepts, radiological concerns, and structural considerations.