Search for Exotic Strange Quark Matter in High Energy Nuclear Reactions

We report on a search for metastable positively and negatively charged states of strange quark matter in Au+Pb reactions at 11.6 A GeV/c in experiment E864. We have sampled approximately six billion 10% most central Au+Pb interactions and have observed no strangelet states (baryon number A < 100 droplets of strange quark matter). We thus set upper limits on the production of these exotic states at the level of 1-6 x 10^{-8} per central collision. These limits are the best and most model independent for this colliding system. We discuss the implications of our results on strangelet production mechanisms, and also on the stability question of strange quark matter.Comment: 21 pages, 9 figures, to be published in Nuclear Physics A (Carl Dover memorial edition

Treatment of bacteriobilia decreases wound infection rates after pancreaticoduodenectomy

AbstractBackgroundAlthough mortality following pancreaticoduodenectomy is decreasing, postoperative morbidity remains high. It was hypothesized that culture-directed treatment of bacteriobilia would decrease the incidence of infectious complications following pancreaticoduodenectomy.MethodsIn a retrospective study of 197 pancreaticoduodenectomy patients, those in the control group (n = 128, 2005–2009) were given perioperative prophylactic antibiotics, whereas those in the treatment group (n = 69, 2009–2011) were continued on antibiotics until intraoperative bile culture results became available. Patients with bacteriobilia received 10 days of antibiotic treatment, which was otherwise discontinued in patients without bacteriobilia. Various complication rates were compared using Fisher's exact test for categorical variables, Wilcoxon rank sum test for ordinal variables, and a two-sample t-test for continuous variables.ResultsDemographics, comorbidities, baseline clinical characteristics, and intraoperative and postoperative variables were similar between the two groups. There were higher incidences of elevated creatinine (19% versus 4%; P = 0.004) and preoperative hyperglycaemia (18% versus 7%; P = 0.053) in the control group. Fewer patients in the control group underwent preoperative biliary stenting (48% versus 67%; P = 0.017) and intraperitoneal drains were placed at the time of resection more frequently in the control group (85% versus 38%; P < 0.001). Bacteriobilia was found in 59% of patients. Treatment of bacteriobilia was associated with a decrease in the rate of postoperative wound infections (12% in the control group versus 3% in the treatment group; P = 0.036) and overall complication severity score (1 in the control group versus 0 in the treatment group; P = 0.027).ConclusionsProlonged antibiotic therapy for bacteriobilia may decrease postoperative wound infection rates after pancreaticoduodenectomy. A randomized prospective trial is warranted to provide evidence to further support this practice

Assembly, Verification, and Initial Annotation of the NIA Mouse 7.4K cDNA Clone Set

A set of 7407 cDNA clones (NIA mouse 7.4K) was assembled from >20 cDNA libraries constructed mainly from early mouse embryos, including several stem cell libraries. The clone set was assembled from embryonic and newborn organ libraries consisting of ∼120,000 cDNA clones, which were initially re-arrayed into a set of ∼11,000 unique cDNA clones. A set of tubes was constructed from the racks in this set to prevent contamination and potential mishandling errors in all further re-arrays. Sequences from this set (11K) were analyzed further for quality and clone identity, and high-quality clones with verified identity were re-arrayed into the final set (7.4K). The set is freely available, and a corresponding database was built to provide comprehensive annotation for those clones with known identity or homology, and has been made available through an extensive Web site that includes many link-outs to external databases and analysis servers. [The sequence data from this study have been submitted to GenBank under accession nos. BQ550036–BQ563104.

Search for charged strange quark matter produced in 11.5A GeV/c Au+Pb collisions

We present results of a search for strange quark matter (strangelets) in 11.5A GeV/c Au + Pb collisions from the 1994 and 1995 runs of experiment E864 at Brookhaven's Alternating Gradient Synchrotron. We observe no strangelet candidates and set a 90% confidence level upper limit of approximately 3 X 10(-8) per 10% central interaction for the production of \Z\ = 1 and \Z\ = 2 strangelets over a large mass range and with metastable lifetimes of about 50 ns or more. These results place constraints primarily on quark-gluon plasma based production models for strangelets. [S0031-9007(97)04465-7]

Antiproton production in 11.5A GeV/c Au+Pb nucleus-nucleus collisions

We present the first results from the E864 Collaboration on the production of antiprotons in 10% central 11.5A GeV/c Au + Ph nucleus collisions at the Brookhaven Alternating Gradient Synchrotron. We report invariant multiplicities for antiproton production in the kinematic region 1.4 < y < 2.2 and 50 < p(T) < 300 MeV/c, and compare our data with a first collision scaling model and previously published results from the E878 Collaboration. The differences between the E864 and E878 antiproton measurements and the implications for antihyperon production are discussed