143 research outputs found

    Macropolyhedral boron-containing cluster chemistry. Ligand-induced two-electron variations of intercluster bonding intimacy. Structures of nineteen-vertex[(eta(5)-C5Me5) HIrB18H19(PMe2Ph)] and the related carbene complex [(eta(5)-C5Me5)HIrB18H19{C(NHMe)(2)}]

    Get PDF
    Addition of PMe2Ph to fused-cluster syn-[(η5-C5Me5)IrB18H20] 1 to give [(η5-C5Me5)HIrB18H19(PMe2Ph)] 3 entails a diminution in the degree of intimacy of the intercluster fusion, rather than retention of inter-subcluster binding intimacy and a nido → arachno conversion of the character of either of the subclusters. Reaction with MeNC gives [(η5-C5Me5)HIrB18H19{C(NHMe)2}] 4 which has a similar structure, but with the ligand now being the carbene {:C(NHMe)2}, resulting from a reductive assembly reaction involving two MeNC residues and the loss of a carbon atom

    Macropolyhedral boron-containing cluster chemistry: two-electron variations in intercluster bonding intimacy. Contrasting structures of 19-vertex [(eta(5)-C5Me5)HIrB18H19(PHPh2)] and [(eta(5) -C5Me5)IrB18H18(PH2Ph)]

    Get PDF
    Fused double-cluster [(5-C5Me5)IrB18H18(PH2Ph)]8, from syn-[(5-C5Me5)IrB18H20] 1 and PH2Ph, retains the three-atoms-in-common cluster fusion intimacy of 1, in contrast to [(5-C5Me5)HIrB18H19(PHPh2)]6, from PHPh2 with 1, which exhibits an opening to a two atoms-in-common cluster fusion intimacy. Compound 8 forms via spontaneous dihydrogen loss from its precursor [(5-C5Me5)HIrB18H19(PH2Ph)]7, which has two-atoms-in-common cluster-fusion intimacy and is structurally analogous to 6

    Inter-rater reliability of the EPUAP pressure ulcer classification system using photographs

    No full text
    Background. Many classification systems for grading pressure ulcers are discussed in the literature. Correct identification and classification of a pressure ulcer is important for accurate reporting of the magnitude of the problem, and for timely prevention. The reliability of pressure ulcer classification systems has rarely been tested. Aims and objectives. The purpose of this paper is to examine the inter-rater reliability of classifying pressure ulcers according to the European Pressure Ulcer Advisory Panel classification system when using pressure ulcer photographs.Design. Survey was among pressure ulcer experts.Methods. Fifty-six photographs were presented to 44 pressure ulcer experts. The experts classified the lesions as normal skin, blanchable erythema, pressure ulcer (four grades) or incontinence lesion. Inter-rater reliability was calculated.Results. The multirater-Kappa for the entire group of experts was 0.80 (P < 0.001).Various groups of experts obtained comparable results. Differences in classifications are mainly limited to 1 degree of difference. Incontinence lesions are most often confused with grade 2 (blisters) and grade 3 pressure ulcers (superficial pressure ulcers).Conclusions. The inter-rater reliability of the European Pressure Ulcer Advisory Panel classification appears to be good for the assessment of photographs by experts. The difference between an incontinence lesion and a blister or a superficial pressure ulcer does not always seem clear.Relevance to clinical practice. The ability to determine correctly whether a lesion is a pressure ulcer lesion is important to assess the effectiveness of preventive measures. In addition, the ability to make a correct distinction between pressure ulcers and incontinence lesions is important as they require different preventive measures. A faulty classification leads to mistaken measures and negative results. Photographs can be used as a practice instrument to learn to discern pressure ulcers from incontinence lesions and to get to know the different grades of pressure ulcers. The Pressure Ulcer Classification software package has been developed to facilitate learning

    Heavy Quarks and Heavy Quarkonia as Tests of Thermalization

    Full text link
    We present here a brief summary of new results on heavy quarks and heavy quarkonia from the PHENIX experiment as presented at the "Quark Gluon Plasma Thermalization" Workshop in Vienna, Austria in August 2005, directly following the International Quark Matter Conference in Hungary.Comment: 8 pages, 5 figures, Quark Gluon Plasma Thermalization Workshop (Vienna August 2005) Proceeding

    Single Electrons from Heavy Flavor Decays in p+p Collisions at sqrt(s) = 200 GeV

    Get PDF
    The invariant differential cross section for inclusive electron production in p+p collisions at sqrt(s) = 200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range $0.4 <= p_T <= 5.0 GeV/c at midrapidity (eta <= 0.35). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e. charm quarks or, at high p_T, bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined as sigma_(c c^bar) = 0.92 +/- 0.15 (stat.) +- 0.54 (sys.) mb.Comment: 329 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Nuclear Modification of Electron Spectra and Implications for Heavy Quark Energy Loss in Au+Au Collisions at sqrt(s_NN)=200 GeV

    Get PDF
    The PHENIX experiment has measured mid-rapidity transverse momentum spectra (0.4 < p_T < 5.0 GeV/c) of electrons as a function of centrality in Au+Au collisions at sqrt(s_NN)=200 GeV. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of pi^0 and eta mesons, were removed. The resulting non-photonic electron spectra are primarily due to the semi-leptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to non-photonic electrons in p+p collisions. A significant suppression of electrons at high p_T is observed in central Au+Au collisions, indicating substantial energy loss of heavy quarks.Comment: 330 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Independent susceptibility markers for atrial fibrillation on chromosome 4q25

    Get PDF
    Background-: Genetic variants on chromosome 4q25 are associated with atrial fibrillation (AF). We sought to determine whether there is more than 1 susceptibility signal at this locus. Methods and results-: Thirty-four haplotype-tagging single-nucleotide polymorphisms (SNPs) at the 4q25 locus were genotyped in 790 case and 1177 control subjects from Massachusetts General Hospital and tested for association with AF. We replicated SNPs associated with AF after adjustment for the most significantly associated SNP in 5066 case and 30 661 referent subjects from the German Competence Network for Atrial Fibrillation, Atherosclerosis Risk In Communities Study, Cleveland Clinic Lone AF Study, Cardiovascular Health Study, and Rotterdam Study. All subjects were of European ancestry. A multimarker risk score composed of SNPs that tagged distinct AF susceptibility signals was constructed and tested for association with AF, and all results were subjected to meta-analysis. The previously reported SNP, rs2200733, was most significantly associated with AF (minor allele odds ratio 1.80, 95% confidence interval 1.50 to 2.15, P=1.2×10) in the discovery sample. Adjustment for rs2200733 genotype revealed 2 additional susceptibility signals marked by rs17570669 and rs3853445. A graded risk of AF was observed with an increasing number of AF risk alleles at SNPs that tagged these 3 susceptibility signals. Conclusions-: We identified 2 novel AF susceptibility signals on chromosome 4q25. Consideration of multiple susceptibility signals at chromosome 4q25 identifies individuals with an increased risk of AF and may localize regulatory elements at the locus with biological relevance in the pathogenesis of AF

    Measurement of Transverse Single-Spin Asymmetries for Mid-rapidity Production of Neutral Pions and Charged Hadrons in Polarized p+p Collisions at sqrt(s) = 200 GeV

    Get PDF
    The transverse single-spin asymmetries of neutral pions and non-identified charged hadrons have been measured at mid-rapidity in polarized proton-proton collisions at sqrt(s) = 200 GeV. The data cover a transverse momentum (p_T) range 0.5-5.0 GeV/c for charged hadrons and 1.0-5.0 GeV/c for neutral pions, at a Feynman-x (x_F) value of approximately zero. The asymmetries seen in this previously unexplored kinematic region are consistent with zero within statistical errors of a few percent. In addition, the inclusive charged hadron cross section at mid-rapidity from 0.5 < p_T < 7.0 GeV/c is presented and compared to NLO pQCD calculations. Successful description of the unpolarized cross section above ~2 GeV/c using NLO pQCD suggests that pQCD is applicable in the interpretation of the asymmetry results in the relevant kinematic range.Comment: 331 authors, 6 pages text, 2 figures, 3 tables. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration

    Full text link
    Extensive experimental data from high-energy nucleus-nucleus collisions were recorded using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The comprehensive set of measurements from the first three years of RHIC operation includes charged particle multiplicities, transverse energy, yield ratios and spectra of identified hadrons in a wide range of transverse momenta (p_T), elliptic flow, two-particle correlations, non-statistical fluctuations, and suppression of particle production at high p_T. The results are examined with an emphasis on implications for the formation of a new state of dense matter. We find that the state of matter created at RHIC cannot be described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted to Nuclear Physics A as a regular article; v3 has minor changes in response to referee comments. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Diving into the vertical dimension of elasmobranch movement ecology

    Get PDF
    Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements
    corecore