Extra force and extra mass from noncompact Kaluza-Klein theory in a cosmological model

Using the Hamilton-Jacobi formalism, we study extra force and extra mass in a recently introduced noncompact Kaluza-Klein cosmological model. We examine the inertial 4D mass $m_0$ of the inflaton field on a 4D FRW bulk in two examples. We find that $m_0$ has a geometrical origin and antigravitational effects on a non inertial 4D bulk should be a consequence of the motion of the fifth coordinate with respect to the 4D bulk.Comment: final version to be published in EPJ

The evolution of the universe from noncompact Kaluza-Klein theory

We develope a 5D mechanism inspired in the Campbell's theorem, to explain the (neutral scalar field governed) evolution of the universe from a initially inflationary expansion that has a change of phase towards a decelerated expansion and thereinafter evolves towards the present day observed celerated (quintessential) expansion.Comment: version accepted in Eur. Phys. J.

Chiral-loop and vector-meson contributions to eta -> pi pi gamma gamma decays

The process eta -> pi0 pi0 gamma gamma is discussed in Chiral Perturbation Theory (ChPT) extending two recent analyses. Special attention is devoted to one-loop corrections, eta-eta' mixing effects and vector-meson dominance of ChPT counter-terms. The less interesting eta -> pi^+ pi^- gamma gamma transition is briefly discussed too.Comment: 15 pages, 3 Postscript figures, uses epsfig.st

Study of the decay asymmetry parameter and CP violation parameter in the Lambdac+ --> Lambda pi+ decay

Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter alpha(Lambdac) in Lambdac --> Lambda pi decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter : A = [alpha(Lambdac)+alpha(antiLambda_c)]/[alpha(Lambdac)-alpha(antiLambda_c)]. We obtain alpha(Lambdac)=-0.78+-0.16+-0.13 and A = -0.07+-0.19+-0.12 where errors are statistical and systematic.Comment: 18 pages, to be submitted to Phys. Lett. B For a list of the FOCUS collaboration, see http://www-focus.fnal.gov/authors.htm

Electromagnetic Dissociation as a Tool for Nuclear Structure and Astrophysics

Coulomb dissociation is an especially simple and important reaction mechanism. Since the perturbation due to the electric field of the (target) nucleus is exactly known, firm conclusions can be drawn from such measurements. Electromagnetic matrixelements and astrophysical S-factors for radiative capture processes can be extracted from experiments. We describe the basic elements of the theory of nonrelativistic and relativistic electromagnetic excitation with heavy ions. This is contrasted to electromagnetic excitation with leptons (electrons), with their small electric charge and the absence of strong interactions. We discuss various approaches to the study of higher order electromagnetic effects and how these effects depend on the basic parameters of the experiment. The dissociation of neutron halo nuclei is studied in a zero range model using analytical methods. We also review ways how to treat nuclear interactions, show their characteristics and how to avoid them (as far as possible). We review the experimental results from a theoretical point of view. Of special interest for nuclear structure physics is the appearence of low lying electric dipole strength in neutron rich nuclei. Applications of Coulomb dissociation to some selected radiative capture reactions relevant for nuclear astrophysics are discussed. The Coulomb dissociation of 8B is relevant for the solar neutrino problem. The potential of the method especially for future investigations of (medium) heavy exotic nuclei for nuclear structure and astrophysics is explored. We conclude that the Coulomb dissociation mechanism is theoretically well understood, the potential difficulties are identified and can be taken care of. Many interesting experiments have been done in this field and many more are expected in the future.Comment: review article accepted for publication in "Prog. in Part. and Nucl. Physics", 75 pages, 31 figure

Coping with the demands of being a collegiate student-athlete: an exploratory investigation coupled with a set of procedural guidelines for athletic department personnel and related services providers

Research in sport psychology has identified some general reactions of collegiate student-athletes when meeting the academic requirements and sport performance demands of their institutions. Despite such awareness, limited information has been reported regarding: (a) the extent to which the day to day and longer range demands are considered as problematic and stressful for collegiate student-athletes; (b) how student-athletes cope with these situations; and (c) student-athletes' views on being provided support in managing their role as student and athlete. In an effort to obtain a more in depth understanding of these issues, a survey was created and distributed electronically to 550 student-athletes enrolled at an NCAA Division-1 college in Pennsylvania, with data being collected and used from 231 participants. Data for the entire sample was analyzed to identify areas of sport, school, and life that respondents found stressful, along with the coping mechanisms they used in their self management as student-athletes. Data was then analyzed based on gender, year in college, and sport. Out of the fifteen items included in the survey, twelve were rated as stressful by more than half of the participants. Although many items were rated as stressful, 5 out of the 12 items received moderate to extreme stress ratings. Specifically, not meeting their own expectations and grades received the highest stress ratings followed by pressure to win, balancing sport and academic demands, and being nervous before or during competition. In order to help manage these stressors, a majority of the student-athletes reported that they spend time with friends, take a break, exercise, and ask friends and family for advice, suggesting that they utilize both problem-focused and emotion-focused coping skills. Responses from the survey were used to create a set of guidelines for athletic department personnel and other professionals working with collegiate student-athletes in an effort to increase their understanding of stress and coping and how to further proceed in learning how to balance sport and academic demands.Psy.DIncludes bibliographical references (p. 212-216)by Denise Dreitlein SteinerIncludes abstrac