University of Costa Rica

About: University of Costa Rica is a education organization based out in San José, Costa Rica. It is known for research contribution in the topics: Population & Venom. The organization has 9817 authors who have published 16781 publications receiving 238208 citations. The organization is also known as: UCR & Universidad de Costa Rica.

Universality of Generalized Parton Distributions in Light-Front Holographic QCD.

Abstract: The structure of generalized parton distributions is determined from light-front holographic QCD up to a universal reparametrization function w(x) which incorporates Regge behavior at small x and inclusive counting rules at x→1 A simple ansatz for w(x) that fulfills these physics constraints with a single-parameter results in precise descriptions of both the nucleon and the pion quark distribution functions in comparison with global fits The analytic structure of the amplitudes leads to a connection with the Veneziano model and hence to a nontrivial connection with Regge theory and the hadron spectrum

Further Study of the Linear Trinickel(II) Complex of Dipyridylamide

Abstract: The title compound, Ni3(dpa)4Cl2 (dpa = di(2-pyridyl)amido anion), first reported 30 years ago, structurally characterized in 1991, has been obtained in two new crystal forms, Ni3(dpa)4Cl2·2CH2Cl2 (tetragonal, space group I4, with a = 27.3046(7) A, c = 12.2452(2) A, Z = 8) and Ni3(dpa)4Cl2·THF (orthorhombic, space group Pccn, with a = 12.673(1) A, b = 14.138(3) A, c = 23.890(2) A, Z = 4). They have been examined structurally, and the magnetic properties of one of them determined from 2 to 300 K. Also the proton NMR spectrum has been recorded. These data allow the following conclusions to be drawn: (1) the molecular structure is invariant in the three crystalline forms and has a symmetrical chain of nickel atoms, (2) the terminal metal atoms each have two unpaired electrons, while the central one is typical of diamagnetic square-planar NiII complexes, (3) the magnetic moments of the two terminal nickel(II) ions display antiferromagnetic coupling, with 2J = −108 cm-1, and (4) the Ni3 chain remains symmetr...

Future time perspective as a motivational variable: Content and extension of future goals affect the quantity and quality of motivation

Abstract: In the first part we briefly discuss the concept of future time perspective (FTP) as a cognitive-motivational construct. By setting goals in the rather near or more distant future, human beings develop their individual FTP that can be characterized by its content (i.e., what people are striving for) and extension or depth (i.e. how far into the future individuals set their goals). Individual differences in the content and exten- sion of the FTP have motivational consequences. In the second part we discuss our own empirical studies showing that not only does the number of future goals matter, but even more so their motivational content. Finally we will report empirical data on the correlates of present and future temporal orientations among adolescents and emerging adults in Europe, South Africa and Latin America. These empirical studies are based on Future Time Perspective Theory, Expectancy*Value Theory and Self- determination Theory.

Kinesiological factors in vertical jump performance: Differences within individuals

Abstract: The purpose of this study was to examine the changes in both the coordination patterns of segmental actions and the dynamics of vertical jumping that accompany changes in vertical jump performance (VJP) occurring from trial to trial in single subjects. Ground reaction forces and video data were analyzed for 50 maximal vertical jumps for 8 subjects. It was possible to predict VJP from whole-body or even segmental kinematics and kinetics in spite of the small jump performance variability. Best whole-body models included peak and average mechanical power, propulsion time, and peak negative impulse. Best segmental models included coordination variables and a few joint torques and powers. Contrary to expectations, VJP was lower for trials with a proximal-to-distal sequence of joint reversals.