731 research outputs found

    Performance of Timber, Masonry and Earth houses in the Christchurch earthquakes New Zealand September 2010 and February 2011

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    Two earthquakes struck close to Christchurch city in New Zealand generating high level ground excitations that caused severe geotechnical effects and widespread structural damage. This paper focuses on damage to timber and masonry that resulted from the geotechnical effects experienced including liquefaction, lateral spreading, rock fall, horizontal and vertical ground accelerations. Light timber framed construction performed well for life safety but there were a large number seriously damaged, heavy masonry caused significant problems when inadequately reinforced. Changes to the construction standards are needed to improve foundation requirements and lateral wall bracing. Earth building damage to modern houses is discussed in reference to the New Zealand Earth Building Standards, and particularly the non-specific design clauses which specify a consistent reinforcing approach. Double skin pressed earth brick and earth brick veneers performed badly and will be excluded in a future revision. Historic unreinforced earth buildings suffered serious damage that was typical for the level of shakin

    Anomalous Effects of "Guest" Charges Immersed in Electrolyte: Exact 2D Results

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    We study physical situations when one or two "guest" arbitrarily-charged particles are immersed in the bulk of a classical electrolyte modelled by a Coulomb gas of positive/negative unit point-like charges, the whole system being in thermal equilibrium. The models are treated as two-dimensional with logarithmic pairwise interactions among charged constituents; the (dimensionless) inverse temperature β\beta is considered to be smaller than 2 in order to ensure the stability of the electrolyte against the collapse of positive-negative pairs of charges. Based on recent progress in the integrable (1+1)-dimensional sine-Gordon theory, exact formulas are derived for the chemical potential of one guest charge and for the asymptotic large-distance behavior of the effective interaction between two guest charges. The exact results imply, under certain circumstances, anomalous effects such as an effective attraction (repulsion) between like-charged (oppositely-charged) guest particles and the charge inversion in the electrolyte vicinity of a highly-charged guest particle. The adequacy of the concept of renormalized charge is confirmed in the whole stability region of inverse temperatures and the related saturation phenomenon is revised.Comment: 21 pages, 1 figur

    Eureka and beyond: mining's impact on African urbanisation

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    This collection brings separate literatures on mining and urbanisation together at a time when both artisanal and large-scale mining are expanding in many African economies. While much has been written about contestation over land and mineral rights, the impact of mining on settlement, notably its catalytic and fluctuating effects on migration and urban growth, has been largely ignored. African nation-states’ urbanisation trends have shown considerable variation over the past half century. The current surge in ‘new’ mining countries and the slow-down in ‘old’ mining countries are generating some remarkable settlement patterns and welfare outcomes. Presently, the African continent is a laboratory of national mining experiences. This special issue on African mining and urbanisation encompasses a wide cross-section of country case studies: beginning with the historical experiences of mining in Southern Africa (South Africa, Zambia, Zimbabwe), followed by more recent mineralizing trends in comparatively new mineral-producing countries (Tanzania) and an established West African gold producer (Ghana), before turning to the influence of conflict minerals (Angola, the Democratic Republic of Congo and Sierra Leone)

    Pion photoproduction on the nucleon in the quark model

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    We present a detailed quark-model study of pion photoproduction within the effective Lagrangian approach. Cross sections and single-polarization observables are investigated for the four charge channels, γpπ+n\gamma p\to \pi^+ n, γnπp\gamma n\to \pi^- p, γpπ0p\gamma p\to \pi^0 p, and γnπ0n\gamma n\to \pi^0 n. Leaving the πNΔ\pi N\Delta coupling strength to be a free parameter, we obtain a reasonably consistent description of these four channels from threshold to the first resonance region. Within this effective Lagrangian approach, strongly constrainted by the quark model, we consider the issue of double-counting which may occur if additional {\it t}-channel contributions are included.Comment: Revtex, 35 pages, 16 eps figures; version to appear on PR

    Isomeric and β-decay spectroscopy of 173,174Ho

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    β-decay spectroscopy of 173,174Ho (Z =67, N =106,107) was conducted at Radioactive Isotope Beam Factory at RIKEN by using in-flight fission of a 345-MeV/u 238U primary beam. A previously unreported isomeric state at 405 keV with half-life of 3.7(12) μs and a spin and parity of (3/2+) is identified in 173 Ho. Moreover, a new state with a spin and parity of 9− was discovered in 174 Er. The experimental log ft values of 5.84(20) and 5.25(18) suggest an allowed-hindered β decay from the ground state of 174Ho to the Kπ=8−isomeric state in 174Er. Configuration-constrained potential energy surface (PES) calculations were performed and the predictions are in reasonable agreement with the experimental results.Part of the WAS3ABi was supported by the Rare Isotopes Science Project which is funded by MSIP and NRF of Korea. This work was supported by JSPS KAKENHI Grants No. 24740188, No. 25247045, and No. 25287065, STFC (UK authors), the UK National Measurement Office (P.H.R.), the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-06CH11357 (F.G.K.), NRF Korea Grants No. 2016R1D1A1A09917463, No. 2017M2A2A6A02071071 (C.S.L.), No. 2019R1F1A1058370, and No. 2016R1A5A1013277 (K.Y.C.), and Science Foundation Ireland under Grant No. 12/IP/1288 (O.J.R.)

    High pTp_{T} non-photonic electron production in pp+pp collisions at s\sqrt{s} = 200 GeV

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    We present the measurement of non-photonic electron production at high transverse momentum (pT>p_T > 2.5 GeV/cc) in pp + pp collisions at s\sqrt{s} = 200 GeV using data recorded during 2005 and 2008 by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The measured cross-sections from the two runs are consistent with each other despite a large difference in photonic background levels due to different detector configurations. We compare the measured non-photonic electron cross-sections with previously published RHIC data and pQCD calculations. Using the relative contributions of B and D mesons to non-photonic electrons, we determine the integrated cross sections of electrons (e++e2\frac{e^++e^-}{2}) at 3 GeV/c<pT< c < p_T <~10 GeV/cc from bottom and charm meson decays to be dσ(Be)+(BDe)dyeye=0{d\sigma_{(B\to e)+(B\to D \to e)} \over dy_e}|_{y_e=0} = 4.0±0.5\pm0.5({\rm stat.})±1.1\pm1.1({\rm syst.}) nb and dσDedyeye=0{d\sigma_{D\to e} \over dy_e}|_{y_e=0} = 6.2±0.7\pm0.7({\rm stat.})±1.5\pm1.5({\rm syst.}) nb, respectively.Comment: 17 pages, 17 figure

    Evolution of the differential transverse momentum correlation function with centrality in Au+Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

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    We present first measurements of the evolution of the differential transverse momentum correlation function, {\it C}, with collision centrality in Au+Au interactions at sNN=200\sqrt{s_{NN}} = 200 GeV. {\it C} exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of {\it C} with increasing centrality to estimate the ratio of the shear viscosity to entropy density, η/s\eta/s, of the matter formed in central Au+Au interactions. We obtain an upper limit estimate of η/s\eta/s that suggests that the produced medium has a small viscosity per unit entropy.Comment: 7 pages, 4 figures, STAR paper published in Phys. Lett.

    Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm

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    The PHENIX experiement has measured the electron-positron pair mass spectrum from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions from light meson decays to e^+e^- pairs have been determined based on measurements of hadron production cross sections by PHENIX. They account for nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair yield remaining after subtracting these contributions is dominated by semileptonic decays of charmed hadrons correlated through flavor conservation. Using the spectral shape predicted by PYTHIA, we estimate the charm production cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which is consistent with QCD calculations and measurements of single leptons by PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables. Submitted to Physics Letters B. v2 fixes technical errors in matching authors to institutions. 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

    Inclusive cross section and double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton

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    The PHENIX experiment presents results from the RHIC 2005 run with polarized proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at mid-rapidity. Unpolarized cross section results are given for transverse momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both lower and higher p_T. The cross section is described well for p_T < 1 GeV/c by an exponential in p_T, and, for p_T > 2 GeV/c, by perturbative QCD. Double helicity asymmetries A_LL are presented based on a factor of five improvement in uncertainties as compared to previously published results, due to both an improved beam polarization of 50%, and to higher integrated luminosity. These measurements are sensitive to the gluon polarization in the proton, and exclude maximal values for the gluon polarization.Comment: 375 authors, 7 pages, 3 figures. Submitted to Phys. Rev. D, Rapid Communications. 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
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