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.

Monte-Carlo calculations of keV electron and positron slowing down in solids

Abstract: A Monte-Carlo simulation technique based on the screened Rutherford differential cross section for the elastic scattering and Gryzinski's semiempirical expression for the inelastic core and valence electron excitation is used to describe electrons and positrons slowing down in solids. The theoretical results are compared with the experimental backscattering, absorption and transmission results for aluminum, silicon, copper, and gold thin film and semi-infinite targets and good agreement is observed. The simulated stopping profiles are fitted with a simple analytic expression. The profiles are Laplace-transformed to give a useful data base for analyzing phenomena associated with slow positron re-emission from solids.

Population variability in space and time

Abstract: One of the most ubiquitous phenomena of all natural populations is their variability in numbers in space and time. However, there are notable differences among populations in the way the population size fluctuates. One of the major challenges in population and community ecology is to explain and understand this variety and to find possible underlying rules that might be modified from case-to-case. Population variability also has a spatial component because fluctuations are often synchronized over relatively large distances. Recently, this has led to growing interest in how 'internal' (density-dependent) processes interact with 'external' factors such as environmental variability.

In vivo human triceps surae and quadriceps femoris muscle function in a squat jump and counter movement jump.

Abstract: An optic fibre method was used to measure in humans in vivo Achilles (ATF) and patellar tendon forces (PTF) during submaximal squat jumps (SJ) and counter movement jumps (CMJ). Normal two-legged jumps on a force plate and one-legged jumps on a sledge apparatus were made by four volunteers. Kinetics, kinematics, and muscle activity from seven muscles were recorded. The loading patterns of the tendomuscular system differed among the jumping conditions, but were similar when the jumping height was varied. Peak PTF were greater than ATF in each condition. In contrast to earlier simulation studies it was observed that tendomuscular force could continue to increase during the shortening of muscle-tendon unit in CMJ. The concentric tendomuscular output was related to the force at the end of the stretching phase while the enhancement of the output in CMJ compared to SJ could not be explained by increases in muscle activity. The stretching phase in CMJ was characterised by little or no electromyogram activity. Therefore, the role of active stretch in creating beneficial conditions for the utilisation of elastic energy in muscle was only minor in these submaximal performances. The modelling, as used in the present study, showed, however, that tendon underwent a stretch-shortening cycle, thus having potential for elastic energy storage and utilisation. In general, the interaction between muscle and tendon components may be organised in a manner that takes advantage of the basic properties of muscle at given submaximal and variable activity levels of normal human locomotion.

The enigma of frequency-dependent selection

Abstract: Frequency-dependent selection is so fundamental to modern evolutionary thinking that everyone `knows' the concept. Yet the term is used to refer to different types of selection. The concept is well defined in the original context of population genetics theory, which focuses on short-term evolutionary change. The original concept becomes ambiguous, however, when used in the context of long-term evolution, where density dependence becomes essential. Weak and strong frequency dependence, as distinguished in this article, refer to two very different forms of selection.

Over 100 Years of Age But Still Entrepreneurially Active in Business: Exploring the Values and Family Characteristics of Old Finnish Family Firms

Abstract: This article, based on an exploratory study of old Finnish family firms, examines two main research questions: “How do certain firms that have been involved in business for over one century perceive and rank their business values?” and “How do the members of the owner-families selfassess their family characteristics in these century-old family firms?” There are only 68 companies that belong to either the FBN-Finland Association (Perheyritysten liitto ry) or the Association of Finnish Entrepreneurs (Suomen yrittajat ry) that are over 100 years of age. The data, based on self-assessments of the present active family executives working at the top level, were drawn from 10 FBN companies and 17 non-FBN companies (response rate 39.7%). When ranking the values, the Finnish respondents generally scored the desirable modes of conduct much higher than the desirable end-states. The top values were honesty, credibility, obeying the law, quality, and industriousness, which are all modes of good ethical conduct. The values of yielding good economic return to owners, willingness to grow, and to get social recognition all scored surprisingly low. The adjectives best describing the characteristics of owning families were: committed, responsible, fair, hardworking, and successful.