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.

Toward a 3-P Model of Workplace Learning: a Literature Review

Abstract: The interest in research focusing on learning taking place at work, through work and for work has considerably increased over the past two decades. The purpose of the paper is to review and structure this wide and diverse research field. A tentative holistic model—the 3-P model of workplace learning—is presented, in relation to which the following six lines of research are identified: (1) studies describing the nature of workplace learning, (2) research on work identities and agency in workplace learning, (3) studies on the development of professional expertise, (4) analyses of competence development in education–work contexts in vocational education and training as well as in higher education, (5) research on communities of practice, and (6) research on organisational learning. The research lines and the holistic 3-P model should be seen as analytic tools for understanding the diversity in workplace learning research. They may also serve as a kind of map for individual researchers, helping them to locate their main areas of interest in this broad field of research and to outline research designs for future studies.

A Surrogate-Assisted Reference Vector Guided Evolutionary Algorithm for Computationally Expensive Many-Objective Optimization

Abstract: We propose a surrogate-assisted reference vector guided evolutionary algorithm (EA) for computationally expensive optimization problems with more than three objectives The proposed algorithm is based on a recently developed EA for many-objective optimization that relies on a set of adaptive reference vectors for selection The proposed surrogate-assisted EA (SAEA) uses Kriging to approximate each objective function to reduce the computational cost In managing the Kriging models, the algorithm focuses on the balance of diversity and convergence by making use of the uncertainty information in the approximated objective values given by the Kriging models, the distribution of the reference vectors as well as the location of the individuals In addition, we design a strategy for choosing data for training the Kriging model to limit the computation time without impairing the approximation accuracy Empirical results on comparing the new algorithm with the state-of-the-art SAEAs on a number of benchmark problems demonstrate the competitiveness of the proposed algorithm

Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy

Abstract: A randomized-controlled single-blind trial was conducted to investigate the clinical, structural and functional effects of peritendinous corticosteroid injections (CORT), eccentric decline squat training (ECC) and heavy slow resistance training (HSR) in patellar tendinopathy. Thirty-nine male patients were randomized to CORT, ECC or HSR for 12 weeks. We assessed function and symptoms (VISA-p questionnaire), tendon pain during activity (VAS), treatment satisfaction, tendon swelling, tendon vascularization, tendon mechanical properties and collagen crosslink properties. Assessments were made at 0 weeks, 12 weeks and at follow-up (half-year). All groups improved in VISA-p and VAS from 0 to 12 weeks (Po0.05). VISA-p and VAS improvements were maintained at follow-up in ECC and HSR but deteriorated in CORT (Po0.05). In CORT and HSR, tendon swelling decreased ( � 13 � 9% and � 12 � 13%, Po0.05) and so did vascularization ( � 52 � 49% and � 45 � 23%, Po0.01) at 12 weeks. Tendon mechanical properties were similar in healthy and injured tendons and were unaffected by treatment. HSR yielded an elevated collagen network turnover. At the half-year follow-up, treatment satisfaction differed between groups, with HSR being most satisfied. Conclusively, CORT has good short-term but poor long-term clinical effects, in patellar tendinopathy. HSR has good short- and long-term clinical effects accompanied by pathology improvement and increased collagen turnover.

Combined effect of elastic energy and myoelectrical potentiation during stretch-shortening cycle exercise

Abstract: In addition to the utilization of muscle's elastic energy enhancement of performance in exercise involving stretch-shortening cycle might be also due to simultaneous increase of myoelectrical activity. This hypothesis was tested by examining three athletes during jumping exercise on force-platform. Vertical jumps were performed with and without preliminary counter-movement, and the jumps were called counter-movement jump (CMJ) and squatting jump (SJ), respectively. In both conditions several jumps were performed also with extra loads on the shoulders (15–220% of b. wt.). Additional droppingjumps (DJ) were executed from different heights (20–100 cm). During jumping exercise myoelectrical activity of selected muscles from the quadriceps femoris was monitored with surface electrodes. The results obtained were similar to those reported in isolated muscle and as expected, the prestretch in CMJ shifted the force-velocity curve of concentric work to the right. In two cases enhancement of performance was attributed primarily to restitution of elastic energy because myoelectrical activity was similar to that observed in SJ. In one subject increased myoelectrical activity was observed during the concentric phase of CMJ. In DJ condition the EMG activity during eccentric phase was much higher than in SJ. Therefore the high performance in this condition was attributed to both elastic energy and reflex potentiation. In eccentric work of CMJ the average force decreased with the increase of stretching speed. This phenomenon was associated with a light increase of EMG activity. The observed results emphasize that both elastic energy and reflex potentiation may operate effectively during stretch-shortening cycle activity.

Maximal strength and power characteristics in isometric and dynamic actions of the upper and lower extremities in middle-aged and older men.

Abstract: Muscle cross-sectional area of the quadriceps femoris (CSAQF), maximal isometric strength (handgrip test and unilateral knee extension/flexion), the shape of isometric force-time curves, and power-load curves during concentric and stretch-shortening cycle (SSC) actions with loads ranging from 15 to 70% of one repetition maximum half-squat (1RMHS) and bench-press (1RMBP) were examined in 26 middle-aged men in the 40-year-old (M40) (mean age 42, range 35-46) and 21 elderly men in the 65-year-old age group (M65) (mean age 65, range 60-74). Maximal bilateral concentric (1RMHS and 1RMBP), unilateral knee extension (isometric; MIFKE and concentric; 1RMKE) strength and muscle CSA in M65 were lower (P < 0.001) than in M40. The individual values of the CSAQF correlated with the individual values of maximal concentric 1RMHS, 1RMKE and MIFKE in M65, while the corresponding correlations were lower in M40. The maximal MIFKE value per CSA of 4.54 +/- 0.7 N m cm-2 in M40 was greater (P < 0. 05-0.01) than that of 4.02 +/- 0.7 N m cm-2 recorded in M65. The maximal rate of force development of the knee extensors and flexors in M65 was lower (P < 0.01-0.001) and the heights in squat and counter-movement jumps as much as 27-29% lower (P < 0.001) than those recorded in M40. M65 showed lower (P < 0.001) concentric power values for both upper and lower extremity performances than those recorded for M40. Maximal power output was maximized at the 30-45% loads for the upper extremity and at the 60-70% loads for the lower extremity extensors in both age groups. Muscle activation of the antagonists was significantly higher (P < 0.01-0.001) during the isometric and dynamic knee extension actions in M65 than in M40. The present results support a general concept that parallel declines in muscle mass and maximal strength take place with increasing age, although loss of strength may vary in both lower and upper extremity muscles in relation to the type of action and that ageing may also lead to a decrease in voluntary neural drive to the muscles. Explosive strength and power seem to decrease with increasing age even more than maximal isometric strength in both actions but power was maximized at the 30-45% loads for the upper and at the 60-70% loads for the lower extremity action in both age groups. High antagonist muscle activity may limit the full movement efficiency depending on the type of muscle action, testing conditions and the velocity and/or the time duration of the action, especially in the elderly.