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 & Neutron. The organization has 8066 authors who have published 25168 publications receiving 725033 citations. The organization is also known as: Jyväskylän yliopisto & Kasvatusopillinen korkeakoulu.

Dynamic packet scheduling performance in UTRA Long Term Evolution downlink

Abstract: In this paper we evaluate the performance of dynamic Packet Scheduling (PS) of 3GPP UTRAN Long Term Evolution (LTE) Downlink. Packet scheduling is of utmost importance in 3G LTE, because all traffic types with different Quality of Service requirements are competing of the resources. We present a decoupled time and frequency domain packet scheduling framework for LTE downlink. Simulation results with three basic packet scheduler combinations with different amount of fairness are presented in four different 3GPP macro simulation cases to show the both extremes in tradeoff between fairness and spectral efficiency. In addition, the effect of multiuser diversity on packet scheduling performance is studied. It is shown that by dividing the packet scheduler into a time domain and a frequency domain and utilizing different algorithms in both domains, the throughput fairness between users can be effectively controlled.

Predicting delayed letter knowledge development and its relation to grade 1 reading achievement among children with and without familial risk for dyslexia.

Abstract: The authors examined the developmental trajectories of children's early letter knowledge in relation to measures spanning and encompassing their prior language-related and cognitive measures and environmental factors and their subsequent Grade 1 reading achievement. Letter knowledge was assessed longitudinally at ages 4.5, 5.0, 5.5, and 6.5 years; earlier language skills and environmental factors were assessed at ages 3.5 and 4.5 years; and reading achievement was assessed at the beginning and end of Grade 1. The analyses were conducted on a longitudinal data set involving children with and without familial risk for dyslexia. Emerging from the trajectory analysis of letter knowledge were 3 separate clusters: delayed (n = 63), linearly growing (n = 73), and precocious (n = 51). The members of the delayed cluster were predominantly children with familial risk for dyslexia, and the members of the precocious cluster were predominantly control group children. Phonological sensitivity, phonological memory, and rapid naming skills predicted delayed letter knowledge. Environmental predictors included level of maternal education and the amount of letter name teaching. Familial risk for dyslexia made a significant contribution to the predictive relations. Membership in the delayed cluster predicted poor reading performance at Grade 1.

Efficient numerical methods for pricing American options under stochastic volatility

Abstract: Five numerical methods for pricing American put options under Heston's stochastic volatility model are described and compared. The option prices are obtained as the solution of a two-dimensional parabolic partial differential inequality. A finite difference discretization on nonuniform grids leading to linear complementarity problems with M-matrices is proposed. The projected SOR, a projected multigrid method, an operator splitting method, a penalty method, and a componentwise splitting method are considered. The last one is a direct method while all other methods are iterative. The resulting systems of linear equations in the operator splitting method and in the penalty method are solved using a multigrid method. The projected multigrid method and the componentwise splitting method lead to a sequence of linear complementarity problems with one-dimensional differential operators that are solved using the Brennan and Schwartz algorithm. The numerical experiments compare the accuracy and speed of the considered methods. The accuracies of all methods appear to be similar. Thus, the additional approximations made in the operator splitting method, in the penalty method, and in the componentwise splitting method do not increase the error essentially. The componentwise splitting method is the fastest one. All multigrid-based methods have similar rapid grid independent convergence rates. They are about two or three times slower that the componentwise splitting method. On the coarsest grid the speed of the projected SOR is comparable with the multigrid methods while on finer grids it is several times slower. ©John Wiley & Sons, Inc. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007

A developmental approach to alcohol drinking behaviour in adulthood: a follow‐up study from age 8 to age 42

Abstract: AIMS: To study the links of family background, child and adolescent social behaviour, and (mal)adaptation with heavy drinking by age 20 and with the frequency of drinking, binge drinking, Cut-down, Annoyed, Guilt, Eye-opener (CAGE) questionnaire scores and problems due to drinking at ages 27 and 42 years. DESIGN: In the Finnish Jyvaskyla Longitudinal Study of Personality and Social Development, data have been collected by interviews, inventories and questionnaires. Behavioural data were gathered at ages 8 and 14; data on alcohol consumption were gathered at ages 14, 20, 27, 36 and 42. PARTICIPANTS: A total of 184 males and 163 females; 94% of the original sample of the 8-year-olds. FINDINGS: Family adversities, externalizing problem behaviours, low school success, truancy and substance use in adolescence were associated in early middle age with problems due to drinking in both genders, and to binge drinking and CAGE scores in females. The antecedents varied, however, across the indicators of drinking and gender. The frequency of drinking was least predictable by the studied antecedents. Childhood and adolescent antecedents and drinking up to age 20 explained 43% of males' and 31% of females' problem drinking atage 42; 31% and 19%, respectively, at age 27. CONCLUSIONS: The early warning signs of drinking problems should be taken seriously in the preventive work for alcohol abuse. Problem drinking in early middle age is preceded by maladjustment to school, early age of onset of drinking and heavy drinking in adolescence even more significantly than problem drinking in early adulthood. Language: en

An evaluation of the microscopical counting methods of the tape in hirst-burkard pollen and spore trap

Abstract: Three different sampling units in current use and different sampling strategies were tested. Randomly placed microscope fields are good in estimating the daily mean concentration, but very big sample size is needed. Traverses across the slide in systematic order are best to estimate the shortterm concentrations and diurnal variation. A formula for the estimation of the error in one transverse traverse is given. Twelve transverse traverses in systematic order is also enough to estimate the daily mean concentration. One or two traverses along the length of the slide give often unreliable estimates because of the irregularities in the transverse variation of the particle concentrations on the slide. For the same reason it is not safe to choose an “effectively collecting area”. Instead the whole width of the tape should be studied.