Effect of nucleon structure variation on the longitudinal response function

Using the quark-meson coupling (QMC) model, we study the longitudinal response function for quasielastic electron scattering from nuclear matter. In QMC the coupling constant between the scalar ($\sigma$) meson and the nucleon is expected to decrease with increasing nuclear density, because of the self-consistent modification of the structure of the nucleon. The reduction of the coupling constant then leads to a smaller contribution from relativistic RPA than in the Walecka model. However, since the electromagnetic form factors of the in-medium nucleon are modified at the same time, the longitudinal response function and the Coulomb sum are reduced by a total of about 20% in comparison with the Hartree contribution. We find that the relativistic RPA and the nucleon structure variation both contribute about fifty-fifty to the reduction of the longitudinal response.Comment: 14 pages, including 3 ps file

Charge Symmetry Violation in Nuclear Physics

The study of charge symmetry violation in nuclear physics is a potentially enormous subject. Through a few topical examples we aim to show that it is not a subject of peripheral interest but rather goes to the heart of our understanding of hadronic systems.Comment: Invited talk at the Int. Conference on Weak and Electromagnetic Interactions in Nuclei, Osaka, June 12-16 199

Charge symmetry breaking in mirror nuclei from quarks

The binding energy differences of the valence proton and neutron of the mirror nuclei, $^{15}$O -- $^{15}$N, $^{17}$F -- $^{17}$O, $^{39}$Ca -- $^{39}$K and $^{41}$Sc -- $^{41}$Ca, are calculated using the quark-meson coupling (QMC) model. The calculation involves nuclear structure and shell effects explicitly. It is shown that binding energy differences of a few hundred keV arise from the strong interaction, even after subtracting all electromagnetic corrections. The origin of these differences may be ascribed to the charge symmetry breaking effects set in the strong interaction through the u and d current quark mass difference.Comment: Revtex (preprint style), 11 pages, 2 postscript figures. The number of parameters has been reduced. (The d current quark mass is also calculated in the model.) Numerical results and figures revised. Version to appear in Phys. Lett.

Subjective skeletal discomfort measured using a comfort questionnaire following a load carriage exercise

Objective: Limited research has been conducted into the effect of load carriage on discomfort and injuries. This study aimed to determine the skeletal discomfort for part-time soldiers who completed a 1-hour field march carrying 24 kg. Methods: A postmarch comfort questionnaire was completed by 127 participants, with exercise withdrawals and postmarch injuries also recorded. Results: The foot was subjectively rated as the most uncomfortable skeletal region. Females reported hip discomfort to be significantly greater than males. The military experience of participants had no difference on the mean perceived comfort ratings of any of the measured regions. Finally, only one participant withdrew from the exercise, with no participants reporting a load carriage injury in the 2 to 3 days proceeding the exercise Conclusions: This study concludes that although a 1-hour period of load carriage causes noteworthy discomfort it is not sufficient to result in noncompletion of a military exercise or cause injury

A Method for Establishing Outdoor Recreation Project Priorities in Alaska

The authors thank Theodore Smith, Edward Kramer and Nat Goodhue of the Division of Parks for information and comments supplied during this study, and Frank Orth, Charles Marsh, Ed Kramer, C.E. Logsdon, and Frank Wooding for reviewing the manuscript. Thanks is also due the Department of Business Administration, University of Alaska, Fairbanks, Dale Swanson, Head, for their cooperation in this research project.The objectives of this study are to define outdoor recreation benefits to the public and to develop a priority ranking method for proposed outdoor recreation projects. A careful analysis of the benefits which people derive from outdoor recreation provides a frame of reference for evaluating a recreational facility. A project should supply those benefits which are most highly demanded by the public. Fifteen benefits of recreation are defined and discussed. They are divided into two major categories; those which accrue to recreational participants and those which accrue to non-participants.This research was supported by a grant from the Division of Parks, State of Alaska

The role of the P11(1710)P_{11}(1710) in the NN→NΣKNN{\to}N{\Sigma}K reaction

Using the resonance model, which was successfully applied for the study of the $pp{\to}p{\Lambda}K^+$ reaction, we investigate $NN{\to}N{\Sigma}K$ reactions that should provide cleaner information about resonance excitations and meson exchange contributions. For this purpose we demonstrate that the invariant mass distribution for the ${\Sigma}K$ system, as well as the Dalitz plot for the $NN{\to}N{\Sigma}K$ reaction, provide direct information about the ${\Sigma}K$ production mechanism, which can be tested in the near future by experiments at COSY.Comment: 25 pages, LaTeX, including 13 ps-figures, UGI-98-36, ADP-98-68/T335, to be publish in Nucl. Phys.

Two-scale scalar mesons in nuclei

We generalize the linear sigma model in order to develop a chiral-invariant model of nuclear structure. The model is natural, and contains not only the usual sigma meson which is the chiral partner of the pion but also a new chiral-singlet that is responsible for the medium-range nucleon-nucleon attraction. This approach provides significant advantages in terms of its description of nuclear matter and finite nuclei in comparison with conventional models based on the linear sigma model.Comment: 12 pages, including 3 tables and 3 figures; preprint number is adde