Online Communication and Adolescent Well-Being: Testing the Stimulation Versus the Displacement Hypothesis

The aim of this study was to contrast the validity of two opposing explanatory hypotheses about the effect of online communication on adolescents' well-being. The displacement hypothesis predicts that online communication reduces adolescents' well-being because it displaces time spent with existing friends, thereby reducing the quality of these friendships. In contrast, the stimulation hypothesis states that online communication stimulates well-being via its positive effect on time spent with existing friends and the quality of these friendships. We conducted an online survey among 1,210 Dutch teenagers between 10 and 17 years of age. Using mediation analyses, we found support for the stimulation hypothesis but not for the displacement hypothesis. We also found a moderating effect of type of online communication on adolescents' well-being: Instant messaging, which was mostly used to communicate with existing friends, positively predicted well-being via the mediating variables (a) time spent with existing friends and (b) the quality of these friendships. Chat in a public chatroom, which was relatively often used to talk with strangers, had no effect on adolescents' well-being via the mediating variables.     

Performance evaluation of efficient multi-objective evolutionary algorithms for design space exploration of embedded computer systems

Multi-objective evolutionary algorithms (MOEAs) have received increasing interest in industry because they have proved to be powerful optimizers. Despite the great success achieved, however, MOEAs have also encountered many challenges in real-world applications. One of the main difficulties in applying MOEAs is the large number of fitness evaluations (objective calculations) that are often needed before an acceptable solution can be found. There are, in fact, several industrial situations in which fitness evaluations are computationally expensive and the time available is very short. In these applications efficient strategies to approximate the fitness function have to be adopted, looking for a trade-off between optimization performance and efficiency. This is the case in designing a complex embedded system, where it is necessary to define an optimal architecture in relation to certain performance indexes while respecting strict time-to-market constraints. This activity, known as design space exploration (DSE), is still a great challenge for the EDA (electronic design automation) community. One of the most important bottlenecks in the overall design flow of an embedded system is due to simulation. Simulation occurs at every phase of the design flow and is used to evaluate a system which is a candidate for implementation. In this paper we focus on system level design, proposing an extensive comparison of the state-of-the-art of MOEA approaches with an approach based on fuzzy approximation to speed up the evaluation of a candidate system configuration. The comparison is performed in a real case study: optimization of the performance and power dissipation of embedded architectures based on a Very Long Instruction Word (VLIW) microprocessor in a mobile multimedia application domain. The results of the comparison demonstrate that the fuzzy approach outperforms in terms of both performance and efficiency the state of the art in MOEA strategies applied to DSE of a parameterized embedded system.     

Psychosocial causes and consequences of pathological gaming

Pathological use of computer and video games has been associated with indicators of psychosocial well-being, such as loneliness, low self-esteem, low social competence, and low life satisfaction. However, few studies have decisively demonstrated whether these indicators of psychosocial well-being are causes or consequences of pathological gaming. To address this gap in the literature, we conducted a two-wave panel study among 851 Dutch adolescents (543 gamers). Causal relations were analyzed using autoregressive structural equation models. These analyses indicated that social competence, self-esteem, and loneliness were significant predictors of pathological gaming six months later. Thus, lower psychosocial well-being can be considered an antecedent of pathological gaming among adolescent gamers. Our analyses further indicated that loneliness was also a consequence of pathological gaming. This suggests that displacement of real-world social interaction resulting from pathological use of video games may deteriorate existing relationships, which could explain the increase in adolescent gamers’ feelings of loneliness.     

Hepatitis a virus and poliovirus 1 inactivation in estuarine water

The hepatitis A virus (HAV) and poliovirus 1 were added to estuarine water samples and their stability in maintenance medium was compared to that in water samples untreated and treated by heat and filtration. The inactivation curves show that the inactivating factor is biological in nature.     

Density and Thermal Expansion of Liquid Au-Cu Alloys

The density of liquid Cu-Au alloys is measured using the technique of electromagnetic levitation, which entails producing a shadow image of the sample. The shadow is recorded by a digital CCD-camera, and the volume of the sample is calculated by an image processing algorithm. The density and thermal expansion of several alloys and the pure elements copper and gold are investigated at various temperatures above their melting points. In addition, the densities are also investigated as a function of the gold concentration at constant temperature. The measured values agree with literature data and with predictions obtained by molecular dynamics. It was found from data analysis that the ideal solution model applies.     

Influence of the structure in low-Pt loading electrodes for polymer electrolyte fuel cells

The influence of the structure and composition of the electrodes on a polymer electrolyte fuel cell (PEFC) performance has been investigated. Electrodes have been prepared by varying the composition of diffusion and/or catalyst layer. Improvements have been obtained by introducing a hydrophobic carbon layer between the carbon paper and the catalyst layer for the gas diffusion backing. High performance has been achieved with low Pt-loading electrodes (0.15 mg/cm²) by including the ionomer Nafion in the catalyst ink. Electrodes have been characterized by SEM-EDX analyses and electrochemical tests in a 50 cm² single cell.     

Scrotal hematoma due to neonatal adrenal hemorrhage: the value of ultrasonography in avoiding unnecessary surgery

Scrotal hematoma is an uncommon presentation of neonatal adrenal hemorrhage. Nine previous cases of such an association have been reported in the literature, and unnecessary surgery was carried out in five of these cases. The authors report three new cases observed during a 3-year period and stress the critical role of scrotal and abdominal ultrasonography in order to avoid unnecessary surgical exploration.     

The influence of Pt on the electrooxidation behaviour of carbon in phosphoric acid

The electrooxidation behaviour of Pt/C catalysts for phosphoric acid fuel cells (PAFC) has been investigated by potentiostatic tests in the potential range 0.6 ÷ 1.0 V (rhe). Results indicate that the corrosion rate increases with an increase in Pt content, and is most noticeable at 0.6 V. At higher potentials anodic dissolution of Pt takes place, thus no metal is available to catalyze the corrosion of carbon. It is concluded that a definite influence of the presence of the supported metal on the extent of carbon corrosion under practical conditions does exist, but the understanding of mechanisms involved in the Pt-promoted carbon corrosion requires further studies.     

Karen Machover (1902–1996): Obituary.

Memorializes K. Machover, whose most visible contribution to psychology was her research with the human figure drawing and Personality Projection in the Drawing of the Human Figure: A Method of Personality Investigation (1949). She also contributed to social activism, teaching, organizational development, and individual therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Superresolution video reconstruction with arbitrary samplinglattices and nonzero aperture time

Printing from an NTSC source and conversion of NTSC source material to high-definition television (HDTV) format are some of the applications that motivate superresolution (SR) image and video reconstruction from low-resolution (LR) and possibly blurred sources. Existing methods for SR image reconstruction are limited by the assumptions that the input LR images are sampled progressively, and that the aperture time of the camera is zero, thus ignoring the motion blur occurring during the aperture time. Because of the observed adverse effects of these assumptions for many common video sources, this paper proposes (i) a complete model of video acquisition with an arbitrary input sampling lattice and a nonzero aperture time, and (ii) an algorithm based on this model using the theory of projections onto convex sets to reconstruct SR still images or video from an LR time sequence of images. Experimental results with real video are provided, which clearly demonstrate that a significant increase in the image resolution can be achieved by taking the motion blurring into account especially when there exists large interframe motion.