A Multiparameter, Numerical Stability Analysis of a Standing Cantilever Conveying Fluid

In this paper, we numerically examine the stability of a standing cantilever conveying fluid in a multiparameter space. Based on nonlinear beam theory, our mathematical model turns out to be replete with exciting behavior, some of which was totally unexpected and novel, and some of which confirm our intuition as well as the work of others. The numerical bifurcation results obtained from applying the Library of Continuation Algorithms (LOCA) reveal a plethora of one, two, and higher codimension bifurcations. For a vertical or standing cantilever beam, bifurcations to buckled solutions (via symmetry breaking) and oscillating solutions are detected as a function of gravity and the fluid-structure interaction. The unfolding of these results as a function of the orientation of the beam compared to gravity is also revealed

Size Selective Parasitism of Rainbow Trout (Oncorhynchus mykiss) by Chestnut Lampreys (Ichthyomyzon castaneus) in an Artificial Setting

Paradigms of optimal resource utilization by animals, both classical and more recent, were not originally developed in the context of parasitism. Though this oversight has slowly been reversed, little attention has been paid to optimal resource utilization by parasitic fishes, such as lampreys. Multiple explanations for host size selection by parasitic lampreys may be plausible, but results from previous studies have been inconsistent. We studied host size selection by Chestnut Lampreys (Ichthyomyzon castaneus) parasitizing Rainbow Trout (Oncorhynchus mykiss) in fish hatchery raceways in north central Arkansas during the late winter and early spring of 2013. Parasitized Rainbow Trout were significantly shorter than non-parasitized conspecifics. Using the relative weight metric of condition, evidence was found that parasitized Rainbow Trout were in better condition than non-parasitized Rainbow Trout. Our findings are not consistent with previous studies of parasitic lamprey host size selection, but do suggest that Chestnut Lampreys are capable of determining a fish’s suitability as a host based on their plumpness even in a setting with low host size heterogeneity and high host density

THE ACCURACY OF THE SKI-JUMPER'S TAKE-OFF

Introduction The Ski-jumper's take-off is the key phase in Ski-jumping. The difficulty lies in the take-off is done a t great speed (20-30 m.6- ) and in a very short amount of time (0.2-0,4sec.). Based on multifactor theory .We have defined 5 factors which are necessary to solve in one movement act: vigour, accuracy, aerodynamics, rotation, arm activity (VAVERKA, 1987).The take-off is accurate in the moment when the acceleration of the center of gravity is finished and passes through the edge of the take-off area. Problem The main goals of t h i s paper are: - quantification of the take-off accuracy (kinematic and dynamic Aspect), - the relation of the accuracy t o the other factors of the take-off and to final performance in ski-jumping, - to create a model of take-off accuracy (kinematic and dynamic point of view) which would be useful in ski-jumper's training method We have been interested in solving these problems Prom the years 1984-1992. We used the following methods: - dynamometry of the ski-jumper's take-off in natural conditions of the jumping hill in Frenstat p.R. (the length of measured platform 6 m, artificially covered jumping-hill), about 800 take-offs were analysed, - kinematic analyses of the take-off (in years 1990-1991, about450 take-offs) analysed from different jumping hills - measurement of the speed during the run-on phase, - statistical and graphical methods. Results The long term observation of these problems revealed: - a large variability of this factor in relation to different levels of performers, different forms of hill surfaces, and patterns of take-off force-time curves, - close relation of accuracy to the length of jump and other factors of the take-off, especially vigour, - t h e possibility to create a statistical model enabling the quantification of the take-off accuracy by using results from dynamometric measurements and kinematic analyses

COMPARISON OF ISOMETRIC AND DYNAMIC METHODS OF STRENGTH TRAINING PROGRAM

The purpose of this study was to determine the difference in the quality of muscle strength employing two methods of strength training (isometric, dynamic). Nineteen male university students volunteered to participate in the experiment, encompassing a five week strength training sessions. The dynamic method was applied to the elbow flexion and extension of the right side (load totalling 60 % of maximal performance) and the isometric method applied on the same muscle groups of the left side (maximal voluntary isometric contraction). Pre- and post-test measurements included maximal isometric strength, the angle a expressed the speed of increasing muscle strength and the number of repetitions performed for each exercise (at a of load 60 % max), as a measure of muscle endurance. No differences were found between the results of strength training when using both methods (isometric, dynamic). A five week training program improved the isometric force by about 8-14 % of pre-test values, and by about 34-54 % in repetition exercises with the load. No differences were exhibited in the rate of the speed of increasing muscle strength

Automating embedded analysis capabilities and managing software complexity in multiphysics simulation part II: application to partial differential equations

A template-based generic programming approach was presented in a previous paper that separates the development effort of programming a physical model from that of computing additional quantities, such as derivatives, needed for embedded analysis algorithms. In this paper, we describe the implementation details for using the template-based generic programming approach for simulation and analysis of partial differential equations (PDEs). We detail several of the hurdles that we have encountered, and some of the software infrastructure developed to overcome them. We end with a demonstration where we present shape optimization and uncertainty quantification results for a 3D PDE application

THE RELATIONSHIPS BETWEEN ANTHROPOMOTORIC BODY DIMENSIONS AND THE FORCE - TIME STRUCTURE OF THE VERTICAL JUMP

INTRODUCTION: The take - off activities are quite various and many of their modifications are used in sport. The final result of the jump is influenced by a great variety of factors such as the quality of produced muscle strength timing of the jump, range of movement, arm activities etc. The basic determinants of many movement activities are the body dimensions (length and mass variables). This paper is focused on the questions concerning the relationship between the forcetime structure of the vertical jump (time, distance, velocity, force, final results) and the body dimensions. METHODS: The counter-movement vertical jump (CMJ) with an arm swing was registered on a KISTLER platform. The reaction force Fz (t) was analysed on an ON-LINE system using software developed in our lab. 23 variables describing the structure of CMJ from the point of view of time, distance, velocity of the centre of mass (CM), and produced force were computed in real time. Eleven values of body dimensions were measured for each subject (length variables of the lower limbs, body height, mass, width of knee, and ankle). The subjects of this research were two groups of students of physical education (men, n=54, age: 18 - 20 years, height: 178.40 ± 6.12cm, body mass: 79.00 ± 6.36 kg; women, n=47, height: 168.48 ± 6.20 cm, body mass: 59.77 ± 6.44 kg). Correlation and factor analysis (STATGRAPHICS package) were used for the statistical analysis. RESULTS: The factor analysis of eleven anthropometric values showed two groups of dependent variables (length parameters and body height - 1st factor, and body mass and width variables - 2nd factor). The three factor model of the CMJ structure selected three groups of dependent variables for both the men and women (1st - time and distance variables, 2nd - impulse momentum and variables of the final results of CMJ, 3rd - variables of the preparatory phase of the CMJ). The factor analysis of body dimension and CMJ variables has shown that the body dimensions are an independent group of variables and that they do not have a relationship to the CMJ structure. CONCLUSION: Factor analysis confirms the relative independence of the three groups of CMJ variables (time and distance, impulse momentum and final variables of the CMJ, the preparatory phase variables). The set of body dimension parameters does not have a relationship to the structure of CMJ. This finding was the same for both groups of men and women

Scaling behavior in economics: I. Empirical results for company growth

We address the question of the growth of firm size. To this end, we analyze the Compustat data base comprising all publicly-traded United States manufacturing firms within the years 1974-1993. We find that the distribution of firm sizes remains stable for the 20 years we study, i.e., the mean value and standard deviation remain approximately constant. We study the distribution of sizes of the ``new'' companies in each year and find it to be well approximated by a log-normal. We find (i) the distribution of the logarithm of the growth rates, for a fixed growth period of one year, and for companies with approximately the same size $S$ displays an exponential form, and (ii) the fluctuations in the growth rates -- measured by the width of this distribution $\sigma_1$ -- scale as a power law with $S$, $\sigma_1\sim S^{-\beta}$. We find that the exponent $\beta$ takes the same value, within the error bars, for several measures of the size of a company. In particular, we obtain: $\beta=0.20\pm0.03$ for sales, $\beta=0.18\pm0.03$ for number of employees, $\beta=0.18\pm0.03$ for assets, $\beta=0.18\pm0.03$ for cost of goods sold, and $\beta=0.20\pm0.03$ for property, plant, & equipment.Comment: 16 pages LateX, RevTeX 3, 10 figures, to appear J. Phys. I France (April 1997

Scaling behavior in economics: II. Modeling of company growth

In the preceding paper we presented empirical results describing the growth of publicly-traded United States manufacturing firms within the years 1974--1993. Our results suggest that the data can be described by a scaling approach. Here, we propose models that may lead to some insight into these phenomena. First, we study a model in which the growth rate of a company is affected by a tendency to retain an ``optimal'' size. That model leads to an exponential distribution of the logarithm of the growth rate in agreement with the empirical results. Then, we study a hierarchical tree-like model of a company that enables us to relate the two parameters of the model to the exponent $\beta$, which describes the dependence of the standard deviation of the distribution of growth rates on size. We find that $\beta = -\ln \Pi / \ln z$, where $z$ defines the mean branching ratio of the hierarchical tree and $\Pi$ is the probability that the lower levels follow the policy of higher levels in the hierarchy. We also study the distribution of growth rates of this hierarchical model. We find that the distribution is consistent with the exponential form found empirically.Comment: 19 pages LateX, RevTeX 3, 6 figures, to appear J. Phys. I France (April 1997

Affective Processes as Potential Pathways Between Intimate Relationship Quality and Perceived Health

Intimate relationship quality has been linked to diverse health outcomes ranging from subjective clinical endpoints like perceived health to objective clinical endpoints like mortality. In major theories of relationship functioning and physical health, affective processes have been consistently presented as a plausible mediator, such that high relationship quality would be thought to impact affective processes directly and to buffer the impact of stress on negative affect generation. However, limited research to date has investigated to what extent changes in relationship quality may impact health via changes in affective processes. In the present study, data on relationship satisfaction, positive and negative affect, perceived health, and stress exposure were collected from couples before and after participating in an online self-help program based on principles of integrative behavioral couple therapy. Paired t-tests were conducted to examine changes in relational and individual functioning, and the SPSS macro MEMORE was used to evaluate a 2-instance repeated-measures path analysis model, wherein changes in perceived health were modeled as occurring via changes in relationship satisfaction and negative affect (i.e., serial mediation). Finally, Steiger&rsquo;s test for equality of dependent correlations was used to test the hypothesis that negative affect and stress exposure would be less strongly correlated post-intervention relative to pre-intervention. Results of the paired t-tests indicated significant increases in relationship satisfaction and decreases in negative affect for both women and men, and significant increases in perceived health for men. Results of the path analyses indicated that improvement in relationship satisfaction was associated with decrease in negative affect for women, but there was not a significant serial mediation effect for either women or men. The between-person association of stress exposure and negative affect was significantly stronger at post-intervention relative to pre-intervention for both men and women, contrary to expectations. Results partially support theories of intimate relationships and health, by suggesting that improving relationship satisfaction can have a positive impact on affective processes. However, there may not be a corresponding short-term impact on perceived health. Continued research is needed to elucidate how and for whom changing relationship satisfaction and affective processes may impact different aspects of health.</p