Showing papers by "University of Jyväskylä published in 1983"

A simple method for measurement of mechanical power in jumping.

Abstract: A simple test for the measurement of mechanical power during a vertical rebound jump series has been devised. The test consists of measuring the flight time with a digital timer (+/- 0.001 s) and counting the number of jumps performed during a certain period of time (e.g., 15-60 s). Formulae for calculation of mechanical power from the measured parameters were derived. The relationship between this mechanical power and a modification of the Wingate test (r = 0.87, n = 12 males) and 60 m dash (r = 0.84, n = 12 males) were very close. The mechanical power in a 60 s jumping test demonstrated higher values (20 W X kgBW-1) than the power in a modified (60 s) Wingate test (7 W X kgBW-1) and a Margaria test (14 W X kgBW-1). The estimated powers demonstrated different values because both bicycle riding and the Margaria test reflect primarily chemo-mechanical conversion during muscle contraction, whereas in the jumping test elastic energy is also utilized. Therefore the new jumping test seems suitable to evaluate the power output of leg extensor muscles during natural motion. Because of its high reproducibility (r = 0.95) and simplicity, the test is suitable for laboratory and field conditions.

An Interactive Multiple Objective Linear Programming Method for a Class of Underlying Nonlinear Utility Functions

Abstract: This paper develops a method for interactive multiple objective linear programming assuming an unknown pseudo concave utility function satisfying certain general properties. The method is an extension of our earlier method published in this journal Zionts, S., Wallenius, J. 1976. An interactive programming method for solving the multiple criteria problem. Management Sci.22 6 652-663.. Various technical problems present in predecessor versions have been resolved. In addition to presenting the supporting theory and algorithm, we discuss certain options in implementation and summarize our practical experience with several versions of the method.

Some biomechanical aspects of the foot and ankle in athletes with and without shin splints

Abstract: Thirteen adult male athletes (long-distance runners and orienteerers without foot problems) and 35 male athletes with shin splints were compared with respect to: 1) the position of the lower leg and the heel while standing, 2) the passive range of mobility in the subtalar joint, and 3) the angular displacement between the calcaneus and the midline of the lower leg (Achilles tendon angle) while running with bare feet on a treadmill. In standing, the two groups differed statistically significantly in the Achilles tendon angle, which values were greater in the shin splint group. With respect to passive mobility, the athletes with shin splints had significantly greater (P less than 0.05-0.01) angular displacement values in inversion, eversion, and in their sum than the control group. While running, the Achilles tendon angle of the shin splint group was significantly greater (P less than 0.01) at the heel strike. Further, the shin splints group had a significantly greater (P less than 0.01) angular displacement between the heel strike and the maximal everted position. The results suggest structural and functional differences in the feet and ankles between healthy athletes and those with shin splints.

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.

Atoms embedded in an electron gas: Phase shifts and cross sections

Abstract: The Fermi-level scattering phase shifts and the transport cross sections are reported for atoms embedded in a homogeneous electron gas. The applications of the results are discussed, using the electronic stopping power for slow ions and impurity resistivity as examples.

Mechanical power test and fiber composition of human leg extensor muscles.

Abstract: The present study was undertaken to assess the relationship between the mechanical power developed during new anaerobic power test and muscular fiber distribution. Ten track and field male athletes were used as subjects, whose muscle fiber composition (m. vastus lateralis) varied from 25 to 58 fast twitch (FT) fibers. The test consisted of measuring the flight time with a special timer during 60 s continuous jumping. A formula was derived to allow the calculation of mechanical power during a certain period of time (e.g., in the present study every 15 s during 60 s of jumping performance). The relationship between the mechanical power for the first 15 s period correlated best with fast twitch (FT) fiber distribution (r = 0.86, p less than 0.005). However, the power output during the successive 15 s periods demonstrated lower correlation with FT, and this relationship became statistically non-significant after 30 s of work. The sensitivity to fatigue of the test was supported by the relationship observed between the decrease of power during 60 s jumping performance and the percentage of FT fibers (r = 0.73, p less than 0.01). Thus, the present findings suggest that muscular performance, as determined by the new jumping test, is influenced by skeletal muscle fiber composition. The new test, which primarily evaluates maximal short term muscular power, also proved sensitive in assessing fatigue patterns during 60 s of strenuous work.

Endurance training reduces the susceptibility of mouse skeletal muscle to lipid peroxidation in vitro.

Abstract: Selected estimates of the lipid peroxidative capacity were assayed in the red and white skeletal muscles of control and endurance-trained mice. Endurance training decreased the lipid peroxidation rate in vitro in both muscle types. The concentration of lipids susceptible to Fe2+-induced lipid peroxidation was greater in the red than in the white skeletal muscle and increased after endurance training in the red muscle. Endurance training, however, decreased highly significantly the sensitivity of red muscle to in vitro stimulated lipid peroxidation. The activity of catalase and the concentration of vitamin E were considerably higher in the red muscle, whereas the activity of glutathione peroxidase was slightly higher in the white muscle. Endurance training caused no changes in these antioxidants. Endurance training increased the concentrations of reduced and total non-protein glutathione in the red skeletal muscle but not in the white muscle. The total sulfhydryl group contents were unaffected. Our results suggest that endurance training may increase the resistance of skeletal muscle to injuries caused by lipid peroxidation.

Quantum Motion of Chemisorbed Hydrogen on Ni Surfaces

Abstract: Quantum mechanical energy levels and wave functions have been calculated for the motion of chemisorbed hydrogen atoms on Ni surfaces. The results show considerable quantum effects for the adatom in both the ground and the excited states. The description of the adparticles as being delocalized along the surface offers a novel interpretation of several phenomena, in particular the vibrational excitations.

Influence of lactate accumulation of EMG frequency spectrum during repeated concentric contractions

Abstract: One hundred and twenty consecutive maximal leg extensions at a constant angular velocity of 1.5 radians . s-1 were performed by nine physical education students. Integrated electromyographic (IEMG) activity and power spectrum density function (PSDF) of the EMG were recorded from m. vastus lateralis, vastus medialis and m. rectus femoris using bipolar surface electrodes. Muscle biopsies were obtained from m. vastus lateralis before and after exercise. Tissue samples were analyzed for muscle fiber type distribution and lactate and glycogen concentration. Muscle force and IEMG decreased in parallel over the exercise period. Thus, the IEMG/force ratio was unchanged. Mean power frequency (MPF) of PSDF of the three nucleus decreased by 10% (p less than 0.001) during the initial 25 contractions with no further decline during the latter part of exercise. The relative contribution of the highest bandwidth (130-500 Hz) of the PSDF decreased (p less than 0.001) between the first and final contractions. Muscle glycogen concentration decreased from 85 +/- 23 to 68 +/- 22 mmol . kg-1 w.w. during the exercise. Muscle and blood lactate concentration averaged 12.1 +/- 8.8 mmol . kg-1 w.w. and 3.8 +/- 0.8 mmol . l-1, respectively. The relative changes in MPF and in the highest bandwidth were correlated with muscle lactate concentration and fiber type distribution: in individuals with a high proportion of fast twitch muscle fibres and/or the greatest lactate accumulation, MPF and high frequency components of EMG PSDF decreased most markedly. Reductions in muscle force and IEMG are suggested to be partly due to a decreased motor neuron firing rate. It is discussed whether lactate or associated metabolic changes are influencing the motor unit action potential through feedback processes.

Relationship between isokinetic performance and ballistic movement.

Abstract: The present experiments were carried out to assess the relationship between the mechanical behaviour of the leg extensor muscles in 12 male athletes during activities of a ballistic type and torque production, during: (1) torque production during isokinetic contraction; (2) ballistic type activities (vertical jumps from static position = SJ, with counter-movement = CMJ and after a fall from different heights = DJ) and (3) a new anaerobic test (Bosco 1983a). This consisted of performing continuous jump work for a certain period of time (e.g., 60s). Both ballistic activities and anaerobic power tests demonstrated the highest relationship with peak torques when this was developed respectively at π and 4.2 rad·s−1. Peak torque was related to SJ (r=0.71, p<0.01); to CMJ (r=0.74, p<0.005); to best DJ (r=0.60, p<0.05), to 15 s anaerobic power (r=0.70, p<0.01) and 60 s anaerobic power (r=0.68, p<0.01). The power output during ballistic activities was much higher than the power measured during zero acceleration performances. The difference noted was explained in the light of the fact that, when jumping, three different extensor muscle groups in each leg contract with re-use during the concentric phase of elastic energy stored during the eccentric phase. The relationship between isokinetic contraction and ballistic motion is discussed in terms of fiber type recruitment and their velocity dependency.

Youthful smoking and drinking in a longitudinal perspective.

Abstract: The incidence and continuity of smoking and drinking, precursory social-behavioral characteristics of smokers and drinkers, and life conditions related to smoking and drinking are described. The study was part of an extensive Finnish longitudinal study of social development, the original sample of which consisted of 8-year-old subjects (196 boys, 173 girls) studied in 1968 by employing peer nomination and teacher ratings. The follow-up studies were made at ages 14 and 20. 154 Ss at age 14 and 135 Ss at age 20 were interviewed about their smoking and drinking habits, among others. The results showed that about 20% of the subjects smoked at age 14 and about 30% at age 20. The proportion of abstainers was about 25% at age 14 and 10% at age 20. The differences between the sexes were negligible. Smoking at age 20 was predictable on the basis of early initiation, but drinking was not. Aggressiveness at age 8, and orientation towards peers and negativism at age 14 predicted male and female smoking and male drinking and alcohol offences at age 20. Social characteristics did not predict female drinking. At age 20, male and female smoking and heavy drinking belonged to the way of life of Reveller, and smoking also to that of Loser. Smoking and drinking were related to parental models at age 20, but in puberty the influence of peers' smoking and drinking was stronger than that of the parental models. Lack of parental encouragement and affectional interaction with the parents was related to female smoking and male drinking. Youthful smoking and drinking were not connected with family socioeconomic status.

Positron Surface States on Clean and Oxidized Al and in Surface Vacancies

Abstract: Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Nieminen, R. M.; Puska, Martti

Alterations of mechanical characteristics of human skeletal muscle during strength training

Abstract: To investigate the influence of strength training on the mechanical characteristics of human skeletal muscle, 14 male subjects went through training of combined heavy concentric and eccentric contractions three times a week for 16 weeks. The strength training program consisted mainly of dynamic exercises for leg extensors with loads of 80 to 120% of one maximum repetition. The force-time curves produced during various vertical jumps were the basis for calculation of various mechanical parameters. In addition to a great increase (p<0.001) in maximal isometric force, heavy resistance strength training also caused significant (p<0.05−0.01) increases in heights and in various mechanical parameters in positive work phases of vertical and drop jumps. The increase in positive force during a fast dynamic contraction was correlated (p<0.01) with the reduced time to produce a certain submaximal force level in isometric condition. No changes in the elastic properties of the muscle were observed as judged from the difference between the counter-movement and squat jumps. When the training was followed by the 8-week detraining period a great decrease (p<0.001) in maximal force took place, but only minor changes (ns) were observed in fast force production.

On a relation between massive Yang-Mills theories and dual string models

Abstract: The relations between mass terms in Yang-Mills theories, projective representations of the group of gauge transformations, boundary conditions on vector potentials and Schwinger terms in local charge algebra commutation relations are discussed. The commutation relations (with Schwinger terms) are similar to the current algebra commutation relations of the SU(N) extended dual string model.

Mass spectra of chlorinated aromatics formed in pulp bleaching: I—chlorinated catechols

Abstract: The fragmentation of chlorinated guaiacols (2-methoxyphenols) on electron impact has been studied. The most common fragmentation processes are interpreted and in some cases the small differences between spectra of positional isomers are explained. In addition to the well-known alkyl-oxygen fission (loss of methyl radical), metastable ion studies and deuterium labelling have indicated several new fragmentation pathways. The most characteristic are the formation of [MCH3HCl]+ and [MCH3Cl]+· ions. In general, however, the spectra of positional isomers are shown to be very similar.

Study of Even Gd Nuclei by Decay of Oriented Tb, With Analysis by Simple Boson Models

Abstract: We have studied low-spin states of 150,152,154,156Gd by nuclear orientation of β-decaying Tb in a Gd host. Especially by means of multipole mixing ratios, including E0/E2, we have checked and revised spin-parities and assignments to (quasi) rotational ground, β and γ bands. For 150Gd we propose the new interpretation 1207.2 keV (0β+), 1518.5 keV (2β+), 1700.1 keV (4β+), 1430.5 keV (2γ+), 1988.0 keV (3γ+), 2080.0 keV (4γ+). For 152,154,156Gd we find agreement with recent literature. Our comparison with theory includes available data on 158,160Gd and on states up to 10g+, 10β+, 7γ+. We review our previously proposed "projection model", which is basically of the Bohr-Mottelson geometrical type; its essential feature is angular-momentum projection from an intrinsic coherent phonon state. The algebraic boson model IBA-1 is also discussed. Both models are applied to energies and to E2 and E0 transition probabilities. Roughly viewed, the fits by both models are good for the energies, fair for the E2 transitions and poor for the E0 transitions. The four-parameter version of IBA-1 applied is unable to reproduce the nonadiabatic details of the bands, while even the two-parameter projection model does better. For 150Gd the simple boson models seem over-extended because of the proximity of doubly magic 14664Gd82. Description of the N = 88-90 shape transition requires discontinuous parameter behaviour in both models.

Susceptibility of mouse skeletal muscles to exercise injuries

Abstract: The susceptibility to exercise-induced myopathy was studied by histological and biochemical methods in various skeletal muscles of mice 3-4 days after a single bout of prolonged running. The degree of exercise injuries varied greatly in different muscles. Soleus and the red deep parts of quadriceps femoris were the most severely affected muscles. Extensive or scattered necrosis of muscle fibers was associated with focal inflammation and a five- to nine-fold increase in the activity of beta-glucuronidase in these muscles. Slight necrotic changes and a two- to three-fold increase in the activity of beta-glucuronidase were observed in tibialis anterior, plantaris, and the red deep parts of gastrocnemius. A statistically significant increase in beta-glucuronidase activity was also observed in the white distal part of quadriceps femoris, biceps femoris, gracilis, extensor digitorum longus, and peroneal muscles but necrotic lesions were infrequent in these muscles. The degree of exercise injuries is probably affected by the different recruitment of muscles during running and by the anatomical location of muscles in separate compartments, which could expose them to different levels of ischemic compression by postexercise edema.

A Study of the Nuclear Structure at High Energy and Low Spin

Abstract: A novel method to study nuclear structure at low spin as a function of temperature is developed and used on 146,148Sm, 154,156Gd and 160,162Dy, by means of the (3He, α) reaction. The nuclear level density for a wide energy range is also studied. The γ-multiplicities and the first generation γ-ray spectra indicate a structure change in deformed nuclei at about 6 MeV.

In-Beam Study of 213Rn, 215Ra and 217Ra: Strongly Enhanced E3 Transitions in Odd-A N = 127 Isotones

Abstract: With the aim of searching for high-spin configurations involving the high-j neutron orbitals, excited states in 213Rn, 215Ra and 217Ra were populated in the bombardment of 208Pb with 13C ions. Gamma-ray singles, excitation functions and angular distributions, pulsed-beam-γ timing and γ-γ(t) coincidences were measured. Six isomeric levels were observed in 213Rn, three in 215Ra while none in 217Ra. The lowest-lying 15/2- states in all odd-A N = 127 isotones are de-excited by E3 transitions with a strength of about 23 W.u, suggesting that they are all coupled to the octupole phonon. In 217Ra no evidence for collective behavior is found despite its closeness to the actinide region. The low-lying states in the level scheme can be interpreted as arising from three-neutron configurations. The wave function of a Jπ = (37/2+) state in 213Rn is proposed to include about 30% admixture from the two-octupole configuration πh9/23f7/2 ⊗ vg9/2 ⊗ (3-)2 since the de-exciting E3 transition has a strength of about 40 W.u. This is the first indication of such an excitation in the lead region.