Flux-Bubble Models and Mesonic Molecules

It has been shown that the string-flip potential model reproduces most of the bulk properties of nuclear matter, with the exception of nuclear binding. Furthermore, it was postulated that this model, with the inclusion of the colour-hyperfine interaction, should produce binding. In some recent work a modified version of the string-flip potential model was developed, called the flux-bubble model, which would allow for the addition of perturbative QCD interactions. In attempts to construct a simple $q\bar q$ nucleon system using the flux-bubble model (which only included colour-Coulomb interactions) difficulties arose with trying to construct a many-body variational wave function that would take into account the locality of the flux-bubble interactions. In this talk we consider a toy system, a mesonic molecule in order to understand these difficulties. En route, a new variational wave function is proposed that may have a significant enough impact on the old string-flip potential model results that the inclusion of perturbative effects may not be needed.Comment: 8 pages, Latex, avec 9 eps files, http://www.physics.carleton.ca/~boyce/papers/mrst97.p

Modeling the strangeness content of hadronic matter

The strangeness content of hadronic matter is studied in a string-flip model that reproduces various aspects of the QCD-inspired phenomenology, such as quark clustering at low density and color deconfinement at high density, while avoiding long range van der Waals forces. Hadronic matter is modeled in terms of its quark constituents by taking into account its internal flavor (u,d,s) and color (red, blue, green) degrees of freedom. Variational Monte-Carlo simulations in three spatial dimensions are performed for the ground-state energy of the system. The onset of the transition to strange matter is found to be influenced by weak, yet not negligible, clustering correlations. The phase diagram of the system displays an interesting structure containing both continuous and discontinuous phase transitions. Strange matter is found to be absolutely stable in the model.Comment: 14 pages, 1 table, 8 eps figures, revtex. Submitted to Phys. Rev. C, Presented at INPC2001 Berkeley, Ca. july 29-Aug

Splenectomy for splenomegaly and secondary hypersplenism

Splenomegaly and secondary hypersplenism may be associated with acute and chronic infections, autoimmune states, portal hypertension or splenic vein thrombosis, and a number of infiltrative and neoplastic conditions involving the spleen. Our experience and that of others with these various conditions demonstrates that the decision to perform splenectomy should be based on well-defined and often strictly limited indications. Except for idiopathic splenomegaly, the presence and severity of secondary hypersplenism or severely symptomatic splenomegaly should be well documented. In each case, the potential for palliation and known mean duration of expected response must be weighed against the increased morbidity and mortality of splenectomy (as compared to operation for “primary” hypersplenism) . La splénomégalie avec hypersplénisme secondaire relève de multiples causes: infection aigue ou chronique, états autoimmunologiques, hypertension portale, thrombose de la veine splénique, lésions tumorales spléniques. L'expérience de l'auteur qui rejoint celle de nombreux collègues lui permet d'affirmer que les indications de la splénectomie doivent être bien définies et sont strictement limitées. A l'exception de la splénomégalie idiopathique, l'existence et l'intensité de l'hypersplénisme, l'importance des symptomes provoqués par la splénomégalie doivent être aprréciées avec précision. Dans chaque cas le potentiel de la rémission de l'affection et la durée de la rémission doivent être pris en considération en fonction de l'éventuelle morbidité et de l'éventuelle mortalité de la splénectomie (par comparaison avec la splénectomie pour hypersplénisme primaire). Eplenomegalia e hiperesplenismo secundario pueden estar asociados con infecciones agudas y crónicas, estados autoinmunes (síndrome de Felty, lupus eritematoso sistémico), “esplenomegalia congestiva” por hipertensión portal o trombosis de la vena esplénica y con una variedad de entidades de tipo infiltrativo y neoplásico que afectan al bazo (sarcoidosis, enfermedad de Gaucher, varios desórdenes mieloproliferativos y linfomas). Nuestra experiencia, y aquella de otros autores, con tales condiciones demuestra que la decisión de realizar esplenectomía debe estar fundamentada en indicaciones bien definidas y estrictamente limitadas. Excepto en casos de esplenomegalia idiopática, la presencia y severidad del hiperesplenismo secundario o de esplenomegalia severamente sintomática debe ser bien documentada. En cada caso debe determinarse el potencial de paliación y la duración de la respuesta que se espera obtener frente a la incrementada morbilidad y mortalidad de la esplenectomía (en comparación con la operación que se realiza por hiperesplenismo “primario”).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41318/1/268_2005_Article_BF01655279.pd

SU(3) String-Flip Potential Models and Nuclear Matter

A Monte Carlo model for nuclear matter using a many body $SU_c(3)$ string flip potential, with fixed colour, is investigated. The potential is approximated by considering colour singlet flux tube formations that connect only three quarks at a time. The model is compared with a similar string flip model, proposed by Horowitz and Piekarewicz \cite{kn:HorowitzI}, that approximates higher order flux tube formations by connecting quarks in colour singlet chains. The former model gives an EMC nucleon ``swelling'' effect, whereas the latter gives an opposite effect. Possible discrepancies between the two models are discussed.Comment: 15 pages with figures included using epsf, postscript version of paper avialable with figures via anonymous ftp from ftp.physics.carleton.ca in /pub/theory/watson/ocipc9317.ps, OCIP/C-93-1