Search results for "equation"
showing 10 items of 4219 documents
Selectivity in Probabilistic Causality: Where Psychology Runs Into Quantum Physics
2011
Given a set of several inputs into a system (e.g., independent variables characterizing stimuli) and a set of several stochastically non-independent outputs (e.g., random variables describing different aspects of responses), how can one determine, for each of the outputs, which of the inputs it is influenced by? The problem has applications ranging from modeling pairwise comparisons to reconstructing mental processing architectures to conjoint testing. A necessary and sufficient condition for a given pattern of selective influences is provided by the Joint Distribution Criterion, according to which the problem of "what influences what" is equivalent to that of the existence of a joint distr…
Entertainment 2.0? The Role of Intrinsic and Extrinsic Need Satisfaction for the Enjoyment of Facebook Use
2014
While intrinsic motivation has received broad attention in recent entertainment research, the effects of extrinsic motivation, such as social pressure to use media, on media enjoyment remain unknown. Based on an online-survey (N = 230), this study tested the effects of intrinsic need satisfaction and perceived social pressure on the enjoyment of Facebook use with structural equation modeling. The results reveal complex effects of extrinsic motivation: While social pressure negatively affected autonomy need satisfaction, it was positively related to competence and relatedness need satisfaction. This study is the first to develop and test a theoretical model of entertainment experience in the…
The Guilty Couch Potato: The Role of Ego Depletion in Reducing Recovery Through Media Use
2014
This article addresses ego depletion as a mechanism influencing media-based stress recovery processes. Using structural equation modeling, relationships between ego depletion, procrastination, guilt, enjoyment, vitality, and recovery experience were tested using data from an online survey (N = 471). Results suggest that ego depletion may increase the risk of negatively appraising the use of interactive (video games) and noninteractive (television) entertaining media as a form of procrastination. The resulting guilt is negatively related to the recovery experience associated with using entertainment. Therefore, ego-depleted individuals may benefit less from the psychological recovery potenti…
The Irritation Scale as an Instrument to Measure Stress among University Students
2013
AbstractThe objective of this study was to verify the factor validity and structure of the “Irritation Scale” in a sample of 578 Spanish university students. At the same time, the study aimed to verify the criterion-related validity of the scale, analyzing the results obtained through correlation with other variables, such as general self-efficacy, self-regulation, depression, and certain personality dimensions. The results obtained through the Exploratory Structural Equation Modeling approach (ESEM) using Mplus confirmed the presence of two factors in the Irritation Scale, as observed in other international studies within a workplace setting. The significant correlations obtained between t…
Extremal Problems for Elliptic Systems
1998
The specific properties of optimal control problems for elliptic systems, if compared with the case of a single equation, are described. Within them are: strong closures of sets of feasible states; the relaxability via convexification; the type of necessary optimality conditions.
UNIQUENESS OF PERIODIC SOLUTIONS OF THE LIENARD EQUATION
1981
This chapter analyzes the uniqueness of periodic solutions of the Lienard equation. It considers the Lienard equation = y − F ( x ) and y = − x where F (0) = 0 , F ( x ) ∈ Lip( R ). The chapter discusses the existence of periodic solutions. It highlights that the origin is the only stationary point of the system = y − F ( x ) and y = − x , and therefore all nontrivial periodic solutions must circle around the origin. The existence of at least one periodic solution is proved by constructing a Poincare–Bendixson domain. The chapter also emphasizes that to prove the uniqueness of periodic solutions, additional assumptions are also needed. In the literature there are numerous uniqueness results…
Multiple period annuli in Liénard type equations
2010
Abstract We consider the equation x ″ x 1 − x 2 x ′ 2 + g ( x ) = 0 , where g ( x ) is a polynomial. We provide the conditions for existence of multiple period annuli enclosing several critical points.
Local uniqueness of the solutions for a singularly perturbed nonlinear nonautonomous transmission problem
2020
Abstract We consider the Laplace equation in a domain of R n , n ≥ 3 , with a small inclusion of size ϵ . On the boundary of the inclusion we define a nonlinear nonautonomous transmission condition. For ϵ small enough one can prove that the problem has solutions. In this paper, we study the local uniqueness of such solutions.
Friend Influence and Susceptibility to Influence: Changes in Mathematical Reasoning as a Function of Relative Peer Acceptance and Interest in Mathema…
2016
This study investigated friend influence over mathematics achievement in 202 same-sex friendship dyads (106 girl dyads). Participants were in the third grade (around age 9) at the outset. Each friend completed a questionnaire describing interest in mathematics and a standardized mathematical reasoning assessment. Peer nominations provided a measure of peer acceptance. The results revealed evidence that interest in mathematics moderates both the degree to which the higher-accepted friend was influential and the degree to which the lower-accepted friend was susceptible to influence. Specifically, the third-grade mathematical reasoning of the higher-accepted friend predicted an increase in the…
On the long-term response of elastic-perfectly plastic solids to dynamic cyclic loads
1992
It is shown that the long-term response of an elastic-perfectly plastic solid subjected to dynamic actions cyclically varying in time is characterized by stresses, plastic strain rates and velocities that are all periodic with the same period of the external actions, and are in perfect analogy with the quasi-static case; on the other hand, plastic strains and displacements are in general nonperiodic (except in case of alternating plasticity) and may increase indefinitely (except when elastic or plastic shakedown occurs). Besides, the work performed by the external actions in the steady cycle equals the work performed by the elastic stresses (i.e. pertaining to the elastic response of the bo…