CRADA ORNL 91-0046B final report: Assessment of IBM advanced computing architectures

This was a Cooperative Research and Development Agreement (CRADA) with IBM to assess their advanced computer architectures. Over the course of this project three different architectures were evaluated. The POWER/4 RIOS1 based shared memory multiprocessor, the POWER/2 RIOS2 based high performance workstation, and the J30 PowerPC based shared memory multiprocessor. In addition to this hardware several software packages where beta tested for IBM including: ESSO scientific computing library, nv video-conferencing package, Ultimedia multimedia display environment, FORTRAN 90 and C++ compilers, and the AIX 4.1 operating system. Both IBM and ORNL benefited from the research performed in this project and even though access to the POWER/4 computer was delayed several months, all milestones were met

Collective communication routines in PVM

The collective communication routines of scatter, gather, and reduce are frequently implemented as part of the native library for parallel architectures. These operations have been implemented in PVM for use among a heterogeneous system of workstations and parallel computers forming a virtual parallel machine. In the case of the Intel Paragon machines, the PVM implementation of the reduce operation utilizes the corresponding native mode library routines whenever possible. This paper describes the implementation of these collective communication routines in PVM including the utilization of the Intel Paragon native mode operations. Performance data is also given comparing the use of the native Intel Paragon collective routines and the PVM implementation on top of these routines on a dedicated Intel Paragon. For our timing results an average latency of 109 {mu}s is incurred using PVM as compared to the native Intel global sum routine. This extra startup is independent of the size of the message being sent and the number of nodes in the group. It is demonstrated that the use of static groups is preferable in time efficiency over the use of dynamic groups

Multi-vessel stenting during primary percutaneous coronary intervention for acute myocardial infarction. A single-center experience

BACKGROUND: Recanalization of the culprit lesion is the main goal of primary angioplasty for acute ST-segment elevation myocardial infarction (STEMI). Patients presenting with acute myocardial infarction and multivessel disease are, therefore, usually subjected to staged procedures, with the primary percutaneous coronary intervention (PCI) confined to recanalization of the infarct-related artery (IRA). Theoretically at least, early relief of stenoses of non-infarct-related arteries could promote collateral circulation, which could help to limit the infarct size. However, the safety and feasibility of such an approach has not been adequately established. METHODS: In this single-center prospective study we examined 73 consecutive patients who had an acute STEMI and at least one or more lesions > or = 70% in a major epicardial vessel other than the infarct-related artery. In the first 28 patients, forming the multi-vessel (MV) PCI group, all lesions were treated during the primary procedure. In the following 45 patients, forming the culprit-only (CO) PCI group, only the culprit lesion was treated during the initial procedure, followed by either planned-staged or ischemia-driven revascularization of the non-culprit lesions. Fluoroscopy time and contrast dye amount were compared between both groups, and patients were followed up for one year for major adverse cardiac events (MACE) and other significant clinical events. RESULTS: The two groups were well balanced in terms of clinical characteristics, number of diseased vessels and angiographic characteristics of the culprit lesion. In the MV-PCI group, 2.51 lesions per patient were treated using 2.96 +/- 1.34 stents (1.00 lesions and 1.76 +/- 1.17 stents in the CO-PCI group, both p < 0.001). The fluoroscopy time increased from 10.3 (7.2-16.9) min in the CO-PCI group to 12.5 (8.5-19.3) min in the MV-PCI group (p = 0.22), and the amount of contrast used from 200 (180-250) ml to 250 (200-300) ml, respectively (p = 0.16). Peak CK and CK-MB were significantly lower in patients of the MV-PCI group (843 +/- 845 and 135 +/- 125 vs 1652 +/- 1550 and 207 +/- 155 U/l, p < 0.001 and 0.01, respectively). Similar rates of major adverse cardiac events at one year were observed in the two groups (24% and 28% in multi-vessel and culprit treatment groups, p = 0.73). The incidence of new revascularization in both infarct- and non-infarct-related arteries was also similar (24% and 28%, respectively, p = 0.73). CONCLUSION: We may state from this limited experience that a multi-vessel stenting approach for patients with acute STEMI and multi-vessel disease is feasible and probably safe during routine clinical practice. Our data suggest that this approach may help to limit the infarct size. However, larger studies, perhaps using drug-eluting stents, are still needed to further evaluate the safety and efficiency of this procedure, and whether it is associated with a lower need of subsequent revascularization and lower costs

Modeling of complex melting and solidification behavior in laser-irradiated materials (a description and users guide to the LASER8 computer program)

The conceptual foundation of a computational model and a computer program based on it have been developed for treating various aspects of the complex melting and solidification behavior observed in pulsed laser-irradiated materials. A particularly important feature of the modeling is the capability of allowing melting and solidification to occur at temperatures other than the thermodynamic phase change temperatures. As a result, interfacial undercooling and overheating can be introduced and various types of nucleation events can be simulated. Calculations on silicon with the model have shown a wide variety of behavior, including the formation and propagation of multiple phase fronts. Although originally developed as a tool for studying certain problems arising in the field of laser annealing of semiconductors, the program should be useful in treating many types of systems in which phase changes and nucleation phenomena play important roles. This report describes the underlying physical and mathematical ideas and the basic relations used in LASER8. It also provides enough specific and detailed information on the program to serve as a guide for its use; a listing of one version of the program is given

The influence of melt flux and crustal processing on Re–Os isotope systematics of ocean island basalts: Constraints from Galápagos

New rhenium–osmium data for high-MgO (>9 wt.%) basalts from the Galápagos Archipelago reveal a large variation in 187Os/188Os (0.1304 to 0.173), comparable with the range shown by primitive global ocean island basalts (OIBs). Basalts with the least radiogenic 187Os/188Os occur closest to the Galápagos plume stem: those in western Galápagos have low 187Os/188Os, moderate 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb and high 3He/4He whereas basalts in the south also have low 187Os/188Os but more radiogenic 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb and 3He/4He. Our new Os isotope data are consistent with the previously established spatial zonation of the common global isotopic mantle reservoir “C” and ancient recycled oceanic crust in the mantle plume beneath western and southern parts of Galápagos, respectively. Galápagos basalts with the most radiogenic 187Os/188Os (up to 0.1875) typically have moderate MgO (7–9 wt.%) and low Os (<50 pg g−1) but have contrastingly unenriched Sr, Nd and Pb isotope signatures. We interpret this decoupling of chalcophile and lithophile isotopic systems as due to assimilation of young Pacific lower crust during crystal fractionation. Mixing models show the assimilated crust must have higher contents of Re and Os, and more radiogenic 187Os/188Os (0.32), than previously proposed for oceanic gabbros. We suggest the inferred, exceptionally-high radiogenic 187Os of the Pacific crust may be localised and due to sulfides precipitated from hydrothermal systems established at the Galápagos Spreading Centre. High 187Os/188Os Galápagos basalts are found where plume material is being dispersed laterally away from the plume stem to the adjacent spreading centre (i.e. in central and NE parts of the archipelago). The extent to which crustal processing influences 187Os/188Os appears to be primarily controlled by melt flux: as distance from the stem of the Galápagos plume increases, the melt flux decreases and crustal assimilation becomes proportionally greater, accounting for co-variations in Os and 187Os/188Os. The Os concentration threshold below which the 187Os/188Os of Galápagos basalts are contaminated (100 pg g−1) is higher than the canonical value (<50 pg g−1) assumed for many other global OIBs (e.g. for Iceland, Grande Comore and Hawaii). This most likely reflects the low overall melt flux to the crust from the Galápagos plume, which has only a moderate excess temperature and buoyancy flux. Our findings have implications for the interpretation of 187Os/188Os ratios in other ocean island settings, especially those where large variations in 187Os/188Os have been linked to heterogeneity in mantle lithology or sulfide populations: the effect of crustal contamination on 187Os/188Os may be greater than previously recognised, particularly for basalts associated with weak, low melt flux mantle plumes, such as Tristan, Bouvet, Crozet and St Helena

Limits to Sympathetic Evaporative Cooling of a Two-Component Fermi Gas

We find a limit cycle in a quasi-equilibrium model of evaporative cooling of a two-component fermion gas. The existence of such a limit cycle represents an obstruction to reaching the quantum ground state evaporatively. We show that evaporatively the \beta\mu ~ 1. We speculate that one may be able to cool an atomic fermi gas further by photoassociating dimers near the bottom of the fermi sea.Comment: Submitted to Phys. Rev

Transition metal-free, visible-light mediated synthesis of 1,10-phenanthroline derived ligand systems

A broad range of 1,10-phenanthroline substrates was efficiently C-H functionalised, providing rapid, gram-scale access to substituted heteroaromatic cores of broad utility. Furthermore, this C-H functionalisation pathway was extended to the synthesis of previously inaccessible, ultra-soluble, 2,9-bis-triazinyl-1,10-phenanthroline (BTPhen) ligands for advanced nuclear fuel cycles

Exploring the Subtle Effect of Aliphatic Ring Size on Minor Actinide-Extraction Properties and Metal Ion Speciation in Bis-1,2,4-Triazine Ligands

Calling all actinides! Bis-1,2,4-triazine ligands bearing five-membered rings were synthesized and evaluated as actinide-selective extractants. Tuning the size of the aliphatic ring leads to subtle changes in actinide-extraction properties. The origins of these changes were elucidated at the molecular level, paving the way for the rational design of improved actinide-selective extractants for reprocessing of spent nuclear fuel., The synthesis and evaluation of three novel bis-1,2,4-triazine ligands containing five-membered aliphatic rings are reported. Compared to the more hydrophobic ligands 1–3 containing six-membered aliphatic rings, the distribution ratios for relevant f-block metal ions were approximately one order of magnitude lower in each case. Ligand 10 showed an efficient, selective and rapid separation of AmIII and CmIII from nitric acid. The speciation of the ligands with trivalent f-block metal ions was probed using NMR titrations and competition experiments, time-resolved laser fluorescence spectroscopy and X-ray crystallography. While the tetradentate ligands 8 and 10 formed Ln$^{III}$ complexes of the same stoichiometry as their more hydrophobic analogues 2 and 3, significant differences in speciation were observed between the two classes of ligand, with a lower percentage of the extracted 1:2 complexes being formed for ligands 8 and 10. The structures of the solid state 1:1 and 1:2 complexes formed by 8 and 10 with Y$^{III}$, Lu$^{III}$ and Pr$^{III}$ are very similar to those formed by 2 and 3 with Ln$^{III}$. Ligand 10 forms Cm$^{III}$ and Eu$^{III}$ 1:2 complexes that are thermodynamically less stable than those formed by ligand 3, suggesting that less hydrophobic ligands form less stable An$^{III}$ complexes. Thus, it has been shown for the first time how tuning the cyclic aliphatic part of these ligands leads to subtle changes in their metal ion speciation, complex stability and metal extraction affinity

Copyright & Privacy - Through the Copyright Lens, 4 J. Marshall Rev. Intell. Prop. L. 212 (2005)

This panel examines the recent litigation by the recording industry against peer-to-peer (“P2P”) users in the U.S. and Canada. How are users’ identities being obtained? Is the process working well enough or too well? What are the technical, evidentiary, procedural, privacy and substantive copyright issues in play

Hard probes in heavy ion collisions at the LHC: PDFs, shadowing and pApA collisions

This manuscript is the outcome of the subgroup ``PDFs, shadowing and $pA$ collisions'' from the CERN workshop ``Hard Probes in Heavy Ion Collisions at the LHC''. In addition to the experimental parameters for $pA$ collisions at the LHC, the issues discussed are factorization in nuclear collisions, nuclear parton distributions (nPDFs), hard probes as the benchmark tests of factorization in $pA$ collisions at the LHC, and semi-hard probes as observables with potentially large nuclear effects. Also, novel QCD phenomena in $pA$ collisions at the LHC are considered. The importance of the $pA$ program at the LHC is emphasized.Comment: The writeup of the working group "PDFs, shadowing and $pA$ collisions" for the CERN Yellow Report on Hard Probes in Heavy Ion Collisions at the LHC, 121 pages. Subgroup convenors: K.J. Eskola, J.w. Qiu (theory) and W. Geist (experiment). Editor: K.J. Eskol