Isospin non-equilibrium in heavy-ion collisions at intermediate energies

We study the equilibration of isospin degree of freedom in intermediate energy heavy-ion collisions using an isospin-dependent BUU model. It is found that there exists a transition from the isospin equilibration at low energies to non-equilibration at high energies as the beam energy varies across the Fermi energy in central, asymmetric heavy-ion collisions. At beam energies around 55 MeV/nucleon, the composite system in thermal equilibrium but isospin non-equilibrium breaks up into two primary hot residues with N/Z ratios closely related to those of the target and projectile respectively. The decay of these forward-backward moving residues results in the strong isospin asymmetry in space and the dependence of the isotopic composition of fragments on the N/Z ratios of the target and projectile. These features are in good agreement with those found recently in experiments at NSCL/MSU and TAMU, implications of these findings are discussed.Comment: 9 pages, latex, + 3 figures available upon reques

Unusual Presentation of Rare Case of Papillary Adenofibroma of Cervix in a Young Woman

Adenofibroma is an extremely rare benign biphasic neoplasm that is classified into the mixed epithelial and mesenchymal tumor group. These tumors tend to occur in postmenopausal and elderly women. We report the case of a large polypoidal mass per vagina occupying the whole pelvis in a young woman. Preoperative biopsy showed benign epithelial and mullerian mesenchymal components suggestive of mullerian adenofibroma. Total hysterectomy with bilateral salpingectomy was done. The diagnosis of papillary adenofibroma of cervix was made. The total surgery assured complete excision and permitted adequate sampling to exclude malignancy

Isospin relaxation time in heavy-ion collisions at intermediate energies

Using an isospin-dependent transport model, we have studied the isospin and momentum relaxation times in the heavy residues formed in heavy-ion collisions at intermediate energies. It is found that only at incident energies below the Fermi energy, chemical or thermal equilibrium can be reached before dynamical instability is developed in the heavy residues. Also, the isospin relaxation time is shorter (longer) than that for momentum at beam energies lower (higher) than the Fermi energy.Comment: 8 pages Latex + 2 ps Figs.; Phys. Rev. C in pres

Emerging Issues and Innovations in Public PK-12 Education: Implications for Strategic Planning

This research and policy brief from the Metropolitan Educational Research Consortium (MERC) explores emerging issues and innovations that PK-12 school districts should consider when engaging in strategic planning. It includes a discussion of peer reviewed literature related to how PK-12 school districts engage in strategic planning, a thematic analysis of strategic plans across Virginia (as well as the largest school districts in the United States), and an exploration of Google trends related to prominent topics in PK-12 education over the previous five years. It explores the following questions: 1) How do PK-12 school systems engage in strategic planning?, 2) What are the priorities, goals, and strategies in strategic plans across Virginia and the country? 3) What trends in public PK-12 education should school districts consider in their strategic plans? The brief concludes with a series of key takeaways and recommendations for strategic planning in PK-12 school districts

Isospin Physics in Heavy-Ion Collisions at Intermediate Energies

In nuclear collisions induced by stable or radioactive neutron-rich nuclei a transient state of nuclear matter with an appreciable isospin asymmetry as well as thermal and compressional excitation can be created. This offers the possibility to study the properties of nuclear matter in the region between symmetric nuclear matter and pure neutron matter. In this review, we discuss recent theoretical studies of the equation of state of isospin-asymmetric nuclear matter and its relations to the properties of neutron stars and radioactive nuclei. Chemical and mechanical instabilities as well as the liquid-gas phase transition in asymmetric nuclear matter are investigated. The in-medium nucleon-nucleon cross sections at different isospin states are reviewed as they affect significantly the dynamics of heavy ion collisions induced by radioactive beams. We then discuss an isospin-dependent transport model, which includes different mean-field potentials and cross sections for the proton and neutron, and its application to these reactions. Furthermore, we review the comparisons between theoretical predictions and available experimental data. In particular, we discuss the study of nuclear stopping in terms of isospin equilibration, the dependence of nuclear collective flow and balance energy on the isospin-dependent nuclear equation of state and cross sections, the isospin dependence of total nuclear reaction cross sections, and the role of isospin in preequilibrium nucleon emissions and subthreshold pion production.Comment: 101 pages with embedded epsf figures, review article for "International Journal of Modern Physics E: Nuclear Physics". Send request for a hard copy to 1/author