Longitudinal changing relationships between growth tempo and vertical stiffness in movement across maturation

PurposeTo determine whether average growth tempo influenced longitudinal relationships between maturity status and coordination capability using a 15-s hopping task (Aim 1). To investigate how differences in absolute growth tempo were associated with change in coordination capability within and across peak growth (Aim 2).MethodsParticipants were N₁ = 110 (Aim 1) and N₂ = 71 (Aim 2) Australian male competitive swimmers, aged 10–15 years, exposed to repeated-measures tracking (2-years, and 12-months respectively) of maturity status, growth tempo and movement coordination capability. Coordination capability was estimated via vertical stiffness (K_V) in a hopping task, reflected by participant mean K_V and between-jump coefficient of variation (CV).ResultsFor Aim 1, log-linear mixed model trends identified maturity status and growth tempo were significantly associated with K_V mean and K_V CV. For a given maturity status, mean K_V was 9% lower in the ‘High’ average growth tempo group than the ‘Low’ average tempo group. For Aim 2, mixed repeated-measures analyses of variance identified how time points of increased growth tempo were significantly associated with 7–11% reductions in mean K_V, with similar mean K_V decrements irrespective of growth tempo group. Meanwhile, K_VCV only illustrated progressive longitudinal reductions.ConclusionsWithin maturational progression, short-term accelerations in growth tempo corresponded with short-term decreases in K_V mean, suggesting temporary disruptions to movement coordination capability. Measuring growth tempo and applying hopping tasks in specific movement contexts could help consistently identify disturbances in motor coordination.     

How to do things with (recorded) words

The aim of this paper is to evaluate which context determines the illocutionary force of written or recorded utterances—those involved in written texts, films and images, conceived as recordings that can be seen or heard in different occasions. More precisely, my paper deals with the “metaphysical” or constitutive role of context—as opposed to its epistemic or evidential role: my goal is to determine which context is semantically relevant in order to fix the illocutionary force of a speech act, as distinct from the information the addressee uses to ascertain the semantically relevant context. In particular I will try to assess two different perspectives on this problem, a Conventionalist Perspective and an Intentionalist Perspective. Drawing on the literature on indexicals in written texts and recorded messages, I will argue in favor of the Intentionalist Perspective: the relevant context is the one intended by the speaker. Bringing intentions into the picture, however, requires qualification; in particular, I will distinguish my Weak Intentionalist proposal from a Strong Intentionalist one. I will show that the Weak Intentionalist Perspective is flexible enough to deal with cases of delayed communication, but not so unrestricted as to yield counter-intuitive consequences.     

Fractal growth of graphite nodules in iron

It has been found from a large number of statistical tests that graphite nodules in malleable iron grow with time according to a power law. The growth of the nodules and their fractal dimension have been investigated experimentally as a function of annealing time. Based on the assumption of carbon-diffusion-controlled growth in the initial stage, the growth equation is R _G = K ₁ t ^1/(D-1), where R _G is the radius of the graphite nodules, t the time, D the fractal dimension and K ₁ a constant. Assuming cementite-dissolution-controlled growth in the later stages of growth, the relation is R _G = K ₃ t ^3/D , where K ₃ is a constant. The fractal dimension, or the aggregate state of the graphite nodules, strongly influences the growth process.     

Detection of changes in speed and direction of motion: Reaction time analysis

Observers reacted to the change in the movement of a random-dot field whose initial velocity,V _o, was constant for a random period and then switched abruptly to another value,V ₁. The two movements, both horizontally oriented, were either in the same direction (speed increments or decrements), or in the opposite direction but equal in speed (direction reversals). One of the two velocities,V ₀ orV ₁, could be zero (motion onset and offset, respectively). in the range of speeds used, 0–16 deg/sec (dps), the mean reaction time (MRT) for a given value ofV ₀ depended on |V ₁-V ₀| only: MRT ≈r +c(V ₀/|V ₁ ?V ₀|) ^β , where β=2/3,r is a velocity-independent component of MRT, andc(V ₀) is a parameter whose value is constant for low values ofV ₀ (0–4 dps), and increases beginning with some value ofV ₀ between 4 and 8 dps. These and other data reviewed in the paper are accounted for by a model in which the time-position function of a moving target is encoded by mass activation of a network of Reichardt-type encoders. Motion-onset detection (V ₀=0) is achieved by weighted temporal summation of the outputs of this network, the weights assigned to activated encoders being proportional to their squared spatial spans. By means of a “subtractive normalization,” the visual system effectively reduces the detection of velocity changes (a change fromV ₀ toV ₁) to the detection of motion onset (a change from 0 toV ₁-V ₀). Subtractive normalization operates by readjustment of weights: the weights of all encoders are amplified or attenuated depending on their spatial spans, temporal spans, and the initial velocityV ₀. Assignment of weights and weighted temporal summation are thought of as special-purpose computations performed on the dynamic array of activations in the motion-encoding network, without affecting the activations themselves.     

Manual discrimination of force using active finger motion

In these experiments, two plates were grasped between the thumb and forefinger and squeezed together along a linear track. An electromechanical system presented a constant resistance force during the squeeze up to a predetermined location on the track, whereupon the force effectively went to infinity (simulating a wall) or to zero (simulating a cliff). The task of the subject was to discriminate between two alternative levels of the constant resistance force (a reference level and a reference-plus-increment level). Results of these experiments indicate a just noticeable difference of roughly 7% of the reference force using a one-interval paradigm with trial-by-trial feedback over the ranges 2.5≤F _o≤10.0 newtons, 5≤D≤30 mm, 45≤S≤125 mm, and 25≤V≤160 mm/sec, whereF _o is the reference force,D is the distance squeezed,S is the initial finger-span, andV is the mean velocity of the squeeze. These results, based on tests with 5 subjects, are consistent with a wide range of previous results, some of which are associated with other body surfaces and muscle systems and many of which were obtained with different psychophysical methods.     

Finite axiomatization for some intermediate logics

LetN. be the set of all natural numbers (except zero), and letD _n ^* = {k ∈N ∶k|n} ∪ {0} wherek¦n if and only ifn=k.x f or somex∈N. Then, an ordered setD _n ^* = 〈D _n ^* , ? _n , wherex? _ny iffx¦y for anyx, y∈D _n ^* , can easily be seen to be a pseudo-boolean algebra. In [5], V.A. Jankov has proved that the class of algebras {D _n ^* ∶n∈B}, whereB =,{k ∈N∶ ? \(\mathop \exists \limits_{n \in N} \) (n > 1 ≧n ² k)is finitely axiomatizable. The present paper aims at showing that the class of all algebras {D _n ^* ∶n∈B} is also finitely axiomatizable. First, we prove that an intermediate logic defined as follows: $$LD = Cn(INT \cup \{ p_3 \vee [p_3 \to (p_1 \to p_2 ) \vee (p_2 \to p_1 )]\} )$$ finitely approximatizable. Then, defining, after Kripke, a model as a non-empty ordered setH = 〈K, ?〉, and making use of the set of formulas true in this model, we show that any finite strongly compact pseudo-boolean algebra ? is identical with. the set of formulas true in the Kripke modelH _B = 〈P(?), ?〉 (whereP(?) stands for the family of all prime filters in the algebra ?). Furthermore, the concept of a structure of divisors is defined, and the structure is shown to beH D _n ^* = 〈P (D _n ^* ), ?〉for anyn∈N. Finally, it is proved that for any strongly compact pseudo-boolean algebraU satisfying the axiomp ₃∨ [p ₃→(p₁→p₂)∨(p₂→p₁)] there is a structure of divisorsD _* ⁿ such that it is possible to define a strong homomorphism froomiH D _n ^* ontoH D _U . Exploiting, among others, this property, it turns out to be relatively easy to show that \(LD = \mathop \cap \limits_{n \in N} E(\mathfrak{D}_n^* )\) .     

Pseudodiagnosticity

Subjects selected data in order to decide from which of two ‘islands’ an ‘archeological find’ had come. The results replicated two established phenomena in cognitive psychology: (1) the tendency to ignore base rate data given individuating information, and (2) the tendency to seek confirmatory evidence.The major outcome of the study was, however, to reveal a new phenomenon in information search. Subjects displayed a surprising and strong tendency to seek diagnostically worthless information. They then altered their conclusion based on that information. For example, subjects who had already obtained P(D₁/H₁) selected P(D₂/H₁) when P(D₁/H₂) was equally easily available, and when they had no relevant experience to bring to bear on the estimation of P(D₁/H₂). This phenomenon, which appears to be a wholly dysfunctional cognitive tendency, was labeled pseudodiagnosticity.     

The basic parameters of human information processing: Their role in the determination of intelligence

Information psychology deals with information processing in humans which is measured in terms of time units (sec) and information units (bits) and is described by relatively simple models. The model of psychostructure is crucial. It adequately refers to information processing which runs as sequential dichotomous decisions on a ‘yes-no’ or an ‘on-off’ basis. The information unit 1 bit is allocated to each decision.Three basic parameters are important in central information processing: (1) The information flow to the short term storage C_K (15.0 ± 3.1 bit/sec in adults). (2) The duration of presence (retention in primary memory) = T_R (5.4 ± 0.8 sec in adults). (3) The basic speed of learning C_V (depending on the time to retrieval: 0.01 to 1.00 bit/sec in adults). These capacities increase continuously from childhood to adulthood. Within each age group there are remarkable individual differences which exceed variations of biological variables such as body length or brain weight by far.The prerequisite of information psychological measurement is to determine the information content of the stimuli and the reactions and to measure the time between the stimulus and the response. Based on this it is shown that the basic parameters are unspecific, because the type of information, the sensory modalities and the repertory of signs do not alter the results. Besides, the parameters are independent of each other and reach the level of a ratio scale. According to other concepts and other empirical findings, C_K and T_R determine the intelligence quotient including the vocabulary while C_V corresponds to mechanical learning. Tests for these parameters are given.     

How accurate is size and distance perception for very far terrestrial objects? Function and causality

This study investigated absolute estimation of size and distance for natural and artificial objects at viewing distances of 1.1–15.3 km (Experiments 1 and 2) and 0.4–5.0 m (Experiment 3). The main results were that, regardless of distance range, size and distance estimates (S′ andD′) were related to objective size and distance (S andD), respectively, by a power function with an exponent of unity, but great individual differences in exponent were obtained for the far objects. The ratioS′/D′ was reasonably represented byS′/D′ =Kθ ⁿ andS′/D′ = tan(aθ +b), rather thanS′/D′ = tan θ, where θ is the visual angle. Partial correlations were obtained to examine whether (1) apparent size is determined by taking apparent distance into account or (2) both apparent size and apparent distance are determined directly by external stimuli. The combined data for the far objects and the data for the close objects showed that there were high correlations betweenS andS′ and betweenD andD′ and a low correlation betweenD′ andS′. The data of Experiment 2 showed that bothD′ andS′ were highly correlated withS D, and θ, and there was a high positive correlation betweenD′ andS′. It was suggested that the direct-perception model is valid under some situations, but the taking-into-account model is not supported in any set of data.     

Dissimilarity cumulation theory and subjective metrics

We present a new mathematical notion, dissimilarity function, and based on it, a radical extension of Fechnerian Scaling, a theory dealing with the computation of subjective distances from pairwise discrimination probabilities. The new theory is applicable to all possible stimulus spaces subject to the following two assumptions: (A) that discrimination probabilities satisfy the Regular Minimality law and (B) that the canonical psychometric increments of the first and second kind are dissimilarity functions. A dissimilarity function Dab for pairs of stimuli in a canonical representation is defined by the following properties: (1) a≠b?Dab>0; (2) Daa=0; (3) If and , then ; and (4) for any sequence {a_nX_nb_n}_n∈N, where X_n is a chain of stimuli, Da_nX_nb_n→0?Da_nb_n→0. The expression DaXb refers to the dissimilarity value cumulated along successive links of the chain aXb. The subjective (Fechnerian) distance between a and b is defined as the infimum of DaXb+DbYa across all possible chains X and Y inserted between a and b.     

Student-athletes’ dual commitment to school and sport: Compatible or conflicting?

There is general agreement that for collegiate student-athletes to thrive in academics and athletics these individuals must develop and maintain quality commitments to both school and sport throughout college. Yet, limited research has investigated student-athletes’ concurrent negotiation of their discrete commitments to school and sport, and its consequences for these individuals' academic, athletic, and general lives. The purpose of the present study was threefold: (a) identify distinct profiles representing collegiate students-athletes’ dual commitment to school and sport, (b) detect whether these dual commitment profiles demonstrated compatibility versus conflict, and (c) examine the relationships between dual commitment profiles and student-athletes’ academic, athletic, and general life outcomes. A sample of 248 NCAA Division I student-athletes (Mage = 19.87 years, SD = 1.33 years) completed measures of commitment, engagement, and burnout in school and sport, as well as global psychological well-being indices (i.e., life satisfaction and subjective vitality). Using latent profile analyses, results supported a four-profile solution comprising dual commitment profiles with unique configurations of enthusiastic (EC) and constrained (CC) commitment to school and sport: Weak CC-Dominant: School/Strong EC-Dominant: Sport (n = 43), Weak CC-Dominant: School/Strong CC-Dominant: Sport (n = 71), Moderate Commitment: School & Sport (n = 91), and Strong EC-Dominant: School & Sport (n = 43). Dual commitment profiles characterized by enthusiastic-dominant commitment patterns were associated with higher levels of school/sport engagement and global psychological well-being, as well as lower levels of school/sport burnout. Overall, our findings established that collegiate student-athletes are tied to school and sport for various reasons and speak to a potential need for enhanced support networks and services catered to student-athletes’ academic role in the United States.     

Effects of response type on pigeons' sensitivity to variation in reinforcer amount and reinforcer delay

Twelve pigeons, divided into two groups, responded on concurrent nonindependent variable-interval schedules to obtain access to grain by either pecking keys or pressing treadles. Either the amount of grain or the delay to the receipt of grain was varied in separate conditions to determine the sensitivity of relative responding to variation in reinforcer amount (s_A), the sensitivity to variation in reinforcer delay (s_D), and s_A/s_D, a measure related to self-control. There were no significant differences between the two groups in the values of s_A, s_D, and s_A/s_D. These results suggest that the values of s_A, s_D, and s_A/s_D for pigeons may be similar across these two types of responses.     

Hopping skill in individuals with Down syndrome: A qualitative and quantitative assessment

IntroductionIndividuals with Down syndrome (DS) show a delayed acquisition of gross motor skills. Among gross motor skills, hopping is a particular form of jumping that can be performed using one leg. Despite its large use during play and physical activity, this skill in adults with DS has not received much attention so far. Here, we aim at investigating hopping skill in adults with DS both from a quantitative and qualitative point of view.MethodsCenter of mass and dominant leg kinematics during hopping over distance were recorded from 24 adult individuals with DS and from 21 typically developed adults (TD) using two inertial measurement units positioned on the posterior aspect of the lower back and on the lateral malleolus of the hopping leg. From linear acceleration and angular velocity signals, hopping frequency (HF), cycle, stance and flight duration (CD, SD, FD), vertical stiffness (K_V) and peak to peak linear acceleration and angular velocities about the cranio-caudal, antero-posterior and medio-lateral axes were extracted. A qualitative process assessment of the hopping skill was carried out using the performance criteria of the test for gross motor development (TGMD-3). The extracted parameters were submitted to analysis of covariance, with stature as a covariate to rule-out possible confounding effects.ResultsThe qualitative assessment highlighted a poorer hopping performance in the DS group compared to the TD group. DS participants showed higher HF and K_V, shorter CD, SD, FD and lower angular velocity about the cranio-caudal axis compared to the TD group. Significant correlations between the temporal parameters of the quantitative assessment and the results of the qualitative assessment were observed.DiscussionThe poorer motor competence in hopping in individuals with DS compared to TD peers may be related to the shorter flight time and higher vertical stiffness observed in TD peers. The adopted instrumental approach, overcoming the limitations of subjective evaluations, represents a promising opportunity to quantify motor competence in hopping.     

Energy,compressibility and covalency in the carbon subgroup

It is shown that a scaling relation of the type K V ₀/ E ₀ constant, where K₀, V₀ and E₀ are the bulk modulus, volume and total energy respectively at normal pressure, holds for the C subgroup of the Mendeleev periodic table of elements, which consists of C itself, Si, Ge, Sn and Pb. This means that so-called covalency does not contribute significantly to the compressibility of the corresponding substances. The extreme high value of the bulk modulus of diamond is clearly the result of its highest known atomic density.     

Kripke Sheaf Completeness of some Superintuitionistic Predicate Logics with a Weakened Constant Domains Principle

The completeness w.r.t. Kripke frames with equality (or, equivalently, w.r.t. Kripke sheaves, [8] or [4, Sect. 3.6]) is established for three superintuitionistic predicate logics: (Q-H + D*), (Q-H + D*&K), (Q-H + D*&K&J). Here Q-H is intuitionistic predicate logic, J is the principle of the weak excluded middle, K is Kuroda’s axiom, and D* (cf. [12]) is a weakened version of the well-known constant domains principle D. Namely, the formula D states that any individual has ancestors in earlier worlds, and D* states that any individual has ${\neg\neg}$ -ancestors (i.e., ancestors up to ${\neg\neg}$ -equality) in earlier worlds. In particular, the logic (Q-H + D*&K&J) is the Kripke sheaf completion of (Q-H + E&K&J), where E is a version of Markov’s principle (cf. [12]). On the other hand, we show that the logic (Q-H + D*&J) is incomplete w.r.t. Kripke sheaves.     

Hick's law revisited

In 1952, Hick proposed his ‘information theory’, that in making choice reactions the subject gains information at a constant rate such that: Mean reaction time = K log₂ (N + 1).     

Realism,relativism, and constructivism

This paper gives a critical evaluation of the philosophical presuppositions and implications of two current schools in the sociology of knowledge: the Strong Programme of Bloor and Barnes; and the Constructivism of Latour and Knorr-Cetina. Bloor's arguments for his externalist symmetry thesis (i.e., scientific beliefs must always be explained by social factors) are found to be incoherent or inconclusive. At best, they suggest a Weak Programme of the sociology of science: when theoretical preferences in a scientific community, SC, are first internally explained by appealing to the evidence, e, and the standards or values, V, accepted in SC, then a sociologist may sometimes step in to explain why e and V were accepted in SC. Latour's story about the social construction of facts in scientific laboratories is found to be misleading or incredible. The idea that scientific reality is an artifact turns out to have some interesting affinities with classical pragmatism, instrumentalism, phenomenology, and internal realism. However, the constructivist account of theoretical entities in terms of negotiation and social consensus is less plausible than the alternative realist story which explains consensus by the preexistence of mind-independent real entities. The author concludes that critical scientific realism, developed with the concept of truthlikeness, is compatible with the thesis that scientific beliefs or knowledge claims may be relative to various types of cognitive and practical interests. However, the realist denies, with good reasons, the stronger type of relativism which takes reality and truth to be relative to persons, groups, or social interests.This paper was presented at the 8th Inter-Nordic Philosophical Symposium, Oslo, 18–20 May 1989. Some ideas from this paper were first expressed in a lecture in Professor Aant Elzinga's seminar in Gothenburg, 22 April 1988.     

Influence of win-loss ratio on performance,satisfaction and preference for opponents

Hypotheses about the preference for opponents in competitive situations, about performance under various win-loss ratios, and about task and opponent satisfaction under various win-loss ratios were tested. A 5 × 5 latin square with four replications and a repeated measure factor of trials was the design used with 20 female college students as subjects. The five different win percents were W₁₀, W₃₀, W₅₀, W₇₀, and W₉₀. A manipulative maze task was used with subjects receiving 20 trials against each of five confederate opponents. Results indicated that (a) when a person knows little or nothing about her ability level she initially prefers to compete with opponents of low ability but with each subsequent contest opponents of higher ability levels are preferred; (b) subjects performed better in the W₅₀ condition; (c) task satisfaction is higher when the percent of wins is equal to or greater than the percent of losses; and (d) opponent satisfaction is greater for opponents who perform equal to or better than the subject.