Antibaryons in massive heavy ion reactions: Importance of potentials

In the framework of RQMD we investigate antiproton observables in massive heavy ion collisions at AGS energies and compare to preliminary results of the E878 collaboration. We focus here on the considerable influence of the *real* part of an antinucleon--nucleus optical potential on the antiproton momentum spectra

The rodent research animal holding facility as a barrier to environmental contamination

The rodent Research Animal Holding Facility (RAHF), developed by NASA Ames Research Center (ARC) to separately house rodents in a Spacelab, was verified as a barrier to environmental contaminants during a 12-day biocompatibility test. Environmental contaminants considered were solid particulates, microorganisms, ammonia, and typical animal odors. The 12-day test conducted in August 1988 was designed to verify that the rodent RAHF system would adequately support and maintain animal specimens during normal system operations. Additional objectives of this test were to demonstrate that: (1) the system would capture typical particulate debris produced by the animal; (2) microorganisms would be contained; and (3) the passage of animal odors was adequately controlled. In addition, the amount of carbon dioxide exhausted by the RAHF system was to be quantified. Of primary importance during the test was the demonstration that the RAHF would contain particles greater than 150 micrometers. This was verified after analyzing collection plates placed under exhaust air ducts and rodent cages during cage maintenance operations, e.g., waste tray and feeder changeouts. Microbiological testing identified no additional organisms in the test environment that could be traced to the RAHF. Odor containment was demonstrated to be less than barely detectable. Ammonia could not be detected in the exhaust air from the RAHF system. Carbon dioxide levels were verified to be less than 0.35 percent

Lambda flow in heavy-ion collisions: the role of final-state interactions

Lambda flow in Ni+Ni collisions at SIS energies is studied in the relativistic transport model (RVUU 1.0). It is found that for primordial lambdas the flow is considerably weaker than proton flow. The inclusion of final-state interactions, especially the propagation of lambdas in mean-field potential, brings the lambda flow close to that of protons. An accurate determination of lambda flow in heavy-ion experiments is shown to be very useful for studying lambda properties in dense matter.Comment: 14 pages, LaTeX, figures available from [email protected], to appear in Phys. Rev.

Are we close to the QGP? - Hadrochemical vs. microscopic analysis of particle production in ultrarelativistic heavy ion collisions

Ratios of hadronic abundances are analyzed for pp and nucleus-nucleus collisions at sqrt(s)=20 GeV using the microscopic transport model UrQMD. Secondary interactions significantly change the primordial hadronic cocktail of the system. A comparison to data shows a strong dependence on rapidity. Without assuming thermal and chemical equilibrium, predicted hadron yields and ratios agree with many of the data, the few observed discrepancies are discussed.Comment: 12 pages, 4 figure

Collective Flow from the Intranuclear Cascade Model

The phenomenon of collective flow in relativistic heavy ion collisions is studied using the hadronic cascade model ARC. Direct comparison is made to data gathered at the Bevalac, for Au+Au at $p=1-2$ GeV/c. In contrast to the standard lore about the cascade model, collective flow is well described quantitatively without the need for explicit mean field terms to simulate the nuclear equation of state. Pion collective flow is in the opposite direction to nucleon flow as is that of anti-nucleons and other produced particles. Pion and nucleon flow are predicted at AGS energies also, where, in light of the higher baryon densities achieved, we speculate that equation of state effects may be observable.Comment: 9 pages, 2 figures include

Antiproton Production in p+Ap+A Collisions at AGS Energies

Inclusive and semi-inclusive measurements are presented for antiproton ($\bar{p}$) production in proton-nucleus collisions at the AGS. The inclusive yields per event increase strongly with increasing beam energy and decrease slightly with increasing target mass. The $\bar{p}$ yield in 17.5 GeV/c p+Au collisions decreases with grey track multiplicity, $N_g$, for $N_g>0$, consistent with annihilation within the target nucleus. The relationship between $N_g$ and the number of scatterings of the proton in the nucleus is used to estimate the $\bar{p}$ annihilation cross section in the nuclear medium. The resulting cross section is at least a factor of five smaller than the free $\bar{p}-p$ annihilation cross section when assuming a small or negligible formation time. Only with a long formation time can the data be described with the free $\bar{p}-p$ annihilation cross section.Comment: 8 pages, 6 figure

Mutations in PTRH2 cause novel infantile-onset multisystem disease with intellectual disability, microcephaly, progressive ataxia, and muscle weakness

OBJECTIVE: To identify the cause of a so-far unreported phenotype of infantile-onset multisystem neurologic, endocrine, and pancreatic disease (IMNEPD). METHODS: We characterized a consanguineous family of Yazidian-Turkish descent with IMNEPD. The two affected children suffer from intellectual disability, postnatal microcephaly, growth retardation, progressive ataxia, distal muscle weakness, peripheral demyelinating sensorimotor neuropathy, sensorineural deafness, exocrine pancreas insufficiency, hypothyroidism, and show signs of liver fibrosis. We performed whole-exome sequencing followed by bioinformatic analysis and Sanger sequencing on affected and unaffected family members. The effect of mutations in the candidate gene was studied in wild-type and mutant mice and in patient and control fibroblasts. RESULTS: In a consanguineous family with two individuals with IMNEPD, we identified a homozygous frameshift mutation in the previously not disease-associated peptidyl-tRNA hydrolase 2 (PTRH2) gene. PTRH2 encodes a primarily mitochondrial protein involved in integrin-mediated cell survival and apoptosis signaling. We show that PTRH2 is highly expressed in the developing brain and is a key determinant in maintaining cell survival during human tissue development. Moreover, we link PTRH2 to the mTOR pathway and thus the control of cell size. The pathology suggested by the human phenotype and neuroimaging studies is supported by analysis of mutant mice and patient fibroblasts. INTERPRETATION: We report a novel disease phenotype, show that the genetic cause is a homozygous mutation in the PTRH2 gene, and demonstrate functional effects in mouse and human tissues. Mutations in PTRH2 should be considered in patients with undiagnosed multisystem neurologic, endocrine, and pancreatic disease