University of Jyväskylä

About: University of Jyväskylä is a education organization based out in Jyvaskyla, Finland. It is known for research contribution in the topics: Population & Context (language use). The organization has 8066 authors who have published 25168 publications receiving 725033 citations. The organization is also known as: Jyväskylän yliopisto & Kasvatusopillinen korkeakoulu.

Hund's Rules and Spin Density Waves in Quantum Dots

Abstract: Spin density functional theory is used to calculate the ground state electronic structures of circular parabolic quantum dots. We find that such dots either have a spin configuration determined by Hund's rule or make a spin-density-wave-like state with zero total spin. The dependence of the spin-density-wave amplitudes on the density of the two-dimensional electron gas is studied.

The Dark Side of Internet Use: Two Longitudinal Studies of Excessive Internet Use, Depressive Symptoms, School Burnout and Engagement Among Finnish Early and Late Adolescents.

Abstract: Recent research shows an increased concern with well-being at school and potential problems associated with students’ use of socio-digital technologies, i.e., the mobile devices, computers, social media, and the Internet. Simultaneously with supporting creative social activities, socio-digital participation may also lead to compulsive and addictive behavioral patterns affecting both general and school-related mental health problems. Using two longitudinal data waves gathered among 1702 (53 % female) early (age 12–14) and 1636 (64 % female) late (age 16–18) Finnish adolescents, we examined cross-lagged paths between excessive internet use, school engagement and burnout, and depressive symptoms. Structural equation modeling revealed reciprocal cross-lagged paths between excessive internet use and school burnout among both adolescent groups: school burnout predicted later excessive internet use and excessive internet use predicted later school burnout. Reciprocal paths between school burnout and depressive symptoms were also found. Girls typically suffered more than boys from depressive symptoms and, in late adolescence, school burnout. Boys, in turn, more typically suffered from excessive internet use. These results show that, among adolescents, excessive internet use can be a cause of school burnout that can later spill over to depressive symptoms.

Courtship song and immune function in the field cricket Gryllus bimaculatus

Abstract: It has been assumed that sexual ornaments have evolved to reveal males’ health and vigour for females. Choosy females may indirectly use ornaments as an indicator of the presence and effectiveness of genes for resistance against parasites. In this study we tested whether females of the Mediterranean field cricket, Gryllus bimaculatus, can use courtship song as a cue for choosing males with high immunocompetence, measured as encapsulation rate of nylon implants and lytic activity of haemolymph. We found that female crickets preferred courtship songs from males with a high encapsulation rate. Female crickets also had a tendency to prefer courtship songs with high tick rate and long high-frequency tick duration. These preferred song components were positively correlated with encapsulation rate, but negatively correlated with lytic activity of the male. In contrast to previous studies of crickets, there was no correlation between male weight and encapsulation rate or lytic activity. There is some evidence in another cricket species that the ability to encapsulate pathogens is heritable. Thus, in light of this study it seems possible that by preferring males according to their courtship song, females might benefit by increasing the parasite resistance of their offspring. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 79, 503–510.

Maternal affection moderates the impact of psychological control on a child's mathematical performance.

Abstract: This study investigated the extent to which mothers' psychological control predicts their children's mathematical performance during the children's transition from preschool to primary school over and above the impact of maternal affection and behavioral control. Also investigated was the extent to which maternal affection and behavioral control moderate the impact of mothers' psychological control. Children 5-6 years old at baseline (N=196) were followed up 6 times to measure their performance in mathematics over a 3-year period from preschool to 2nd grade. Mothers were asked to fill in a questionnaire measuring their parenting styles once every year over the 3-year period. A high level of psychological control exercised by mothers predicted their children's slow progress in mathematics. However, this impact was particularly evident among those children whose mothers reported a high level of affection. No evidence was found that children's mathematical performance had any effect on their mothers' parenting styles.

Quantifying Artifacts in Ewald Simulations of Inhomogeneous Systems with a Net Charge

Abstract: Ewald summation, which has become the de facto standard for computing electrostatic interactions in biomolecular simulations, formally requires that the simulation box is neutral. For non-neutral systems, the Ewald algorithm implicitly introduces a uniform background charge distribution that effectively neutralizes the simulation box. Because a uniform distribution of counter charges typically deviates from the spatial distribution of counterions in real systems, artifacts may arise, in particular in systems with an inhomogeneous dielectric constant. Here, we derive an analytical expression for the effect of using an implicit background charge instead of explicit counterions, on the chemical potential of ions in heterogeneous systems, which (i) provides a quantitative criterium for deciding if the background charge offers an acceptable trade-off between artifacts arising from sampling problems and artifacts arising from the homogeneous background charge distribution, and (ii) can be used to correct this artifact in certain cases. Our model quantifies the artifact in terms of the difference in charge density between the non-neutral system with a uniform neutralizing background charge and the real neutral system with a physically correct distribution of explicit counterions. We show that for inhomogeneous systems, such as proteins and membranes in water, the artifact manifests itself by an overstabilization of ions inside the lower dielectric by tens to even hundreds kilojoules per mole. We have tested the accuracy of our model in molecular dynamics simulations and found that the error in the calculated free energy for moving a test charge from water into hexadecane, at different net charges of the system and different simulation box sizes, is correctly predicted by the model. The calculations further confirm that the incorrect distribution of counter charges in the simulation box is solely responsible for the errors in the PMFs.