ABSTRACT
The yield for the multistrange Xi(-) hyperon has been measured in 6A GeV Au+Au collisions via reconstruction of its decay products pi(-) and Lambda, the latter also being reconstructed from its daughter tracks of pi(-) and p. The measurement is rather close to the threshold for Xi(-) production and therefore provides an important test of model predictions. The measured yield for Xi(-) and Lambda are compared for several centralities. In central collisions the Xi(-) yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multistrange hadron production approaches chemical equilibrium in high baryon density nuclear matter.
ABSTRACT
Source images are extracted from two-particle correlations constructed from strange and nonstrange hadrons produced in 6A GeV Au+Au collisions. Very different source images result from pp vs p Lambda vs pi(-)pi(-) correlations. Scaling by transverse mass can describe the apparent source size ratio for p/pi(-) but not for Lambda/pi(-) or Lambda/p. These observations suggest important differences in the space-time emission histories for protons, pions, and neutral strange baryons produced in the same events.
ABSTRACT
Rapidity distributions of protons from central 197Au+197Au collisions measured by the E895 Collaboration in the energy range from (2-8)A GeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity,
ABSTRACT
Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy.
ABSTRACT
Infectious crystalline keratopathy (ICK) is a chronic corneal infection characterized by interlamellar plaques of gram-positive coccal bacteria in the absence of inflammatory cells. It generally occurs within a corneal graft. Viridans streptococci are usually isolated, but the clinical response to antibiotics is poor and disparate with the in vitro antimicrobial sensitivities. These features suggest the possibility of unusual bacterial factors in pathogenesis. Four cases caused by nutritionally variant viridans streptococci are described. The organisms were fully characterized. They have a rare nutritional requirement for pyridoxal and require defined culture conditions and specific identification. Nutritional variant streptococci (NVS) are principally described as causing endocarditis, another infection involving an avascular collagenous tissue, and exhibiting similar biologic behavior. Electronmicrographic evidence is also adduced that suggests the possible importance of intracorneal glycocalyx deposition. Such factors might explain the anomalous clinical characteristics of this condition.
Subject(s)
Corneal Diseases/microbiology , Eye Infections, Bacterial/microbiology , Streptococcal Infections/microbiology , Streptococcus/physiology , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/therapeutic use , Bacterial Outer Membrane Proteins/metabolism , Corneal Diseases/drug therapy , Corneal Diseases/pathology , Eye Infections, Bacterial/drug therapy , Eye Infections, Bacterial/pathology , Female , Humans , Keratoplasty, Penetrating , Pyridoxal/metabolism , Streptococcal Infections/drug therapy , Streptococcal Infections/pathology , Streptococcus/isolation & purification , Streptococcus/metabolismABSTRACT
Two patients with infectious crystalline keratopathy associated with topical anesthetic abuse are described. No previously reported predisposing factors existed, including topical corticosteroid use during active Herpes simplex or Acanthamoeba keratitis, or following penetrating keratoplasty. Cultures from corneal biopsies of both patients grew Streptococcus viridans. Both infections resulted in corneal scarring with vascularization. Ultimately, corneal transplantation was performed in one case.