724 research outputs found

    Functionally graded titanium implants: Characteristic enhancement induced by combined severe plastic deformation

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    Commercially pure titanium was processed by equal channel angular pressing (ECAP) and surface mechanical attrition treatment (SMAT) for the purpose of developing functionally graded titanium used for implants and a gradient structure including nanostructured, deformed and undeformed zones were produced on the samples. In particular, it was aimed to design the gradient-structure in the titanium with enhanced properties by applying 4 ECAP passes to form bulk structure of ultrafine-grains and subsequently subjecting SMAT to the surface of ECAPed samples to produce nanostructured surface region. Microstructural examination was made by electron back scatter diffraction (EBSD). Also, microhardness, nanoindentation, topography, roughness and wettability were evaluated. To examine the biological response, human osteosarcoma cells were cultured in contact with the samples in various time periods and morphology change, cell viability and alkaline phosphate activity were conducted also cell morphology was monitored. EBSD showed development of ultrafine-grained structure after 4 passes of ECAP with an average grain size of 500 nm. Applying SMAT resulted in additional refinement in the ECAP samples, particularly in the subsurface regions to a depth of 112 μm. Furthermore, the SMATed samples showed an enhancement in roughness, wettability and hardness magnitudes. Viability enhanced up to 7% in SMATed + ECAPed sample, although the acceptable cell adhesion, improved cell differentiation and mineralization were seen. The combined use of ECAP and SMAT has shown a good potential for optimizing the design of modern functionally graded medical devices and implants

    Fast temporal dynamics and causal relevance of face processing in the human temporal cortex

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    We measured the fast temporal dynamics of face processing simultaneously across the human temporal cortex (TC) using intracranial recordings in eight participants. We found sites with selective responses to faces clustered in the ventral TC, which responded increasingly strongly to marine animal, bird, mammal, and human faces. Both face-selective and face-active but non-selective sites showed a posterior to anterior gradient in response time and selectivity. A sparse model focusing on information from the human face-selective sites performed as well as, or better than, anatomically distributed models when discriminating faces from non-faces stimuli. Additionally, we identified the posterior fusiform site (pFUS) as causally the most relevant node for inducing distortion of conscious face processing by direct electrical stimulation. These findings support anatomically discrete but temporally distributed response profiles in the human brain and provide a new common ground for unifying the seemingly contradictory modular and distributed modes of face processing

    Evidence of a structure in (K)over-bar(0)Lambda(+)(c) consistent with a charged Xi(c)(2930)(+), and updated measurement of (B)over-bar(0) -> (K)over-bar(0)Lambda(+)(c) (Lambda)over-bar(c)(-) at Belle

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    We report evidence for the charged charmed-strange baryon Xi(c)(2930)(+) with a signal significance of 3.9 sigma with systematic errors included. The charged Xi(c)(2930)(+) is found in its decay to K-S(0)Lambda(+)(c) in the substructure of (B) over bar (0) -> K-S(0)Lambda(+)(c)(Lambda) over bar (-)(c) decays. The measured mass and width are [2942.3 +/- 4.4(stat.) +/- 1.5(syst.)] MeV/c(2) and [14.8 +/- 8.8(stat.) +/- 2.5(syst.)] MeV, respectively, and the product branching fraction is B((B) over bar (0) -> Xi(c)(2930)(+)(Lambda) over bar (-)(c)) B(Xi(c)(2930)(+) -> (K) over bar (0)(S)Lambda(+)(c)) = [2.37 +/- 0.51(stat.) +/- 0.31 (syst.)] x 10(-4). We also measure B((B) over bar (0) -> (K) over bar (0)(S)Lambda(+)(c)(Lambda) over bar (-)(c)) = [3.99 +/- 0.76(stat.) +/- 0.51(syst.)] x 10(-4) with greater precision than previous experiments, and present the results of a search for the charmonium-like state Y (4660) and its spin partner, Y-eta, in the Lambda(+)(c)(Lambda) over bar (-)(c) invariant mass spectrum. No clear signals of the Y (4660) or Y-eta are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. Thesemeasurements are obtained from a sample of (772 +/- 11) x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider

    Measurement of the CKM Matrix Element Vcb|V_{cb}| from B0D+νB^{0} \to D^{*-} \ell^+ \nu_\ell at Belle

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    We present a new measurement of the CKM matrix element Vcb|V_{cb}| from B0D+νB^{0} \to D^{*-} \ell^+ \nu_\ell decays, reconstructed with the full Belle data set of 711fb1711 \, \rm fb^{-1} integrated luminosity. Two form factor parameterizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product F(1)ηEWVcb\mathcal{F}(1)\eta_{\rm EW}|V_{cb}| and the decay form factors, where F(1)\mathcal{F}(1) is the normalization factor and ηEW\eta_{\rm EW} is a small electroweak correction. In the CLN parameterization we find F(1)ηEWVcb=(35.06±0.15±0.56)×103\mathcal{F}(1)\eta_{\rm EW}|V_{cb}| = (35.06 \pm 0.15 \pm 0.56) \times 10^{-3}, ρ2=1.106±0.031±0.007\rho^{2}=1.106 \pm 0.031 \pm 0.007, R1(1)=1.229±0.028±0.009R_{1}(1)=1.229 \pm 0.028 \pm 0.009, R2(1)=0.852±0.021±0.006R_{2}(1)=0.852 \pm 0.021 \pm 0.006. For the BGL parameterization we obtain F(1)ηEWVcb=(34.93±0.23±0.59)×103\mathcal{F}(1)\eta_{\rm EW}|V_{cb}|= (34.93 \pm 0.23 \pm 0.59)\times 10^{-3}, which is consistent with the World Average when correcting for F(1)ηEW\mathcal{F}(1)\eta_{\rm EW}. The branching fraction of B0D+νB^{0} \to D^{*-} \ell^+ \nu_\ell is measured to be B(B0D+ν)=(4.90±0.02±0.16)%\mathcal{B}(B^{0}\rightarrow D^{*-}\ell^{+}\nu_{\ell}) = (4.90 \pm 0.02 \pm 0.16)\%. We also present a new test of lepton flavor universality violation in semileptonic BB decays, B(B0De+ν)B(B0Dμ+ν)=1.01±0.01±0.03 \frac{{\cal B }(B^0 \to D^{*-} e^+ \nu)}{{\cal B }(B^0 \to D^{*-} \mu^+ \nu)} = 1.01 \pm 0.01 \pm 0.03~. The errors correspond to the statistical and systematic uncertainties respectively. This is the most precise measurement of F(1)ηEWVcb\mathcal{F}(1)\eta_{\rm EW}|V_{cb}| and form factors to date and the first experimental study of the BGL form factor parameterization in an experimental measurement

    Measurement of the τ\tau lepton polarization and R(D)R(D^*) in the decay BˉDτνˉτ\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau with one-prong hadronic τ\tau decays at Belle

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    With the full data sample of 772×106772 \times 10^6 BBˉB{\bar B} pairs recorded by the Belle detector at the KEKB electron-positron collider, the decay BˉDτνˉτ\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau is studied with the hadronic τ\tau decays τπντ\tau^- \rightarrow \pi^- \nu_\tau and τρντ\tau^- \rightarrow \rho^- \nu_\tau. The τ\tau polarization Pτ(D)P_\tau(D^*) in two-body hadronic τ\tau decays is measured, as well as the ratio of the branching fractions R(D)=B(BˉDτνˉτ)/B(BˉDνˉ)R(D^{*}) = \mathcal{B}(\bar {B} \rightarrow D^* \tau^- \bar{\nu}_\tau) / \mathcal{B}(\bar{B} \rightarrow D^* \ell^- \bar{\nu}_\ell), where \ell^- denotes an electron or a muon. Our results, Pτ(D)=0.38±0.51(stat)0.16+0.21(syst)P_\tau(D^*) = -0.38 \pm 0.51 {\rm (stat)} ^{+0.21}_{-0.16} {\rm (syst)} and R(D)=0.270±0.035(stat)0.025+0.028(syst)R(D^*) = 0.270 \pm 0.035{\rm (stat)} ^{+0.028}_{-0.025}{\rm (syst)}, are consistent with the theoretical predictions of the Standard Model. The polarization values of Pτ(D)>+0.5P_\tau(D^*) > +0.5 are excluded at the 90\% confidence level.Comment: 17 pages, 11 figures, submitted to Physical Review

    Search for CPCP violation in the D+π+π0D^{+}\to\pi^{+}\pi^{0} decay at Belle

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    We search for CPCP violation in the charged charm meson decay D+π+π0D^{+}\to\pi^{+}\pi^{0}, based on a data sample corresponding to an integrated luminosity of 921 fb1\rm 921~fb^{-1} collected by the Belle experiment at the KEKB e+ee^{+}e^{-} asymmetric-energy collider. The measured CPCP violating asymmetry is [+2.31±1.24(stat)±0.23(syst)]%[+2.31\pm1.24({\rm stat})\pm0.23({\rm syst})]\%, which is consistent with the standard model prediction and has a significantly improved precision compared to previous results.Comment: 8 pages, 3 figure

    Measurement of eta_c(1S), eta_c(2S) and non-resonant eta' pi+ pi- production via two-photon collisions

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    We report the measurement of gamma gamma to eta_c(1S), eta_c(2S) to eta' pi+ pi- with eta' decays to gamma rho and eta pi+ pi- using 941 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The eta_c(1S) mass and width are measured to be M = [2984.6\pm0.7 (stat.)\pm2.2 (syst.)] MeV/c^{2} and \Gamma = [30.8^{+2.3}_{-2.2}~(stat.) \pm 2.5~(syst.)] MeV, respectively. First observation of eta_c(2S) to eta' pi+ pi- with a significance of 5.5sigma including systematic error is obtained, and the eta_c(2S) mass is measured to be M = [3635.1\pm3.7~(stat.)\pm2.9~(syst.)] MeV/c^{2}. The products of the two-photon decay width and branching fraction (B) of decays to eta'pi+ pi- are determined to be \Gamma_{gamma gamma}B = [65.4\pm2.6~(stat.)\pm6.9~(syst.)] eV for eta_c(1S) and [5.6^{+1.2}_{-1.1}~(stat.)\pm1.1~(syst.)] eV for eta_c(2S). A new decay mode for the eta_c(1S) to eta'f_0(2080) with f_0(2080) to pi+ pi- is observed with a statistical significance of 20sigma. The f_0(2080) mass and width are determined to be M = [2083^{+63}_{-66}~(stat.)\pm 32~(syst.)] MeV/c^{2} and \Gamma = [178^{+60}_{-178}~(stat.) \pm 55~(syst.)] MeV. The cross sections for gamma gamma to eta' pi+ pi- and eta'f_{2}(1270) are measured for the first time.Comment: 19 pages, 14 figure

    Observation of an alternative χc0(2P)\chi_{c0}(2P) candidate in e+eJ/ψDDˉe^+ e^- \rightarrow J/\psi D \bar{D}

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    We perform a full amplitude analysis of the process e+eJ/ψDDˉe^+ e^- \rightarrow J/\psi D \bar{D}, where DD refers to either D0D^0 or D+D^+. A new charmoniumlike state X(3860)X^*(3860) that decays to DDˉD \bar{D} is observed with a significance of 6.5σ6.5\sigma. Its mass is (386232+2613+403862^{+26}_{-32}{}^{+40}_{-13}) MeV/c2c^2 and width is (20167+15482+88201^{+154}_{-67}{}^{+88}_{-82}) MeV. The JPC=0++J^{PC}=0^{++} hypothesis is favored over the 2++2^{++} hypothesis at the level of 2.5σ2.5\sigma. The analysis is based on the 980 fb1\mathrm{fb}^{-1} data sample collected by the Belle detector at the asymmetric-energy e+ee^+ e^- collider KEKB.Comment: 17 pages, 11 figure
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