Scaled momentum distributions for K-S(0) and Λ /̄ Λ in DIS at HERA

Scaled momentum distributions for the strange hadrons K0S and Λ/Λ¯ were measured in deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 330 pb−1. The evolution of these distributions with the photon virtuality, Q 2, was studied in the kinematic region 10 < Q 2  < 40000 GeV2 and 0.001 < x < 0.75, where x is the Bjorken scaling variable. Clear scaling violations are observed. Predictions based on different approaches to fragmentation were compared to the measurements. Leading-logarithm parton-shower Monte Carlo calculations interfaced to the Lund string fragmentation model describe the data reasonably well in the whole range measured. Next-to-leading-order QCD calculations based on fragmentation functions, FFs, extracted from e + e − data alone, fail to describe the measurements. The calculations based on FFs extracted from a global analysis including e + e −, ep and pp data give an improved description. The measurements presented in this paper have the potential to further constrain the FFs of quarks, anti-quarks and gluons yielding K0S and Λ/Λ¯ strange hadrons

Combined measurement and QCD analysis of the inclusive e(+/-)p scattering cross sections at HERA

A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e ± p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q 2, and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result

Study of tau-pair production at HERA

A study of events containing two tau leptons with high transverse momentum has been performed with the ZEUS detector at HERA, using a data sample corresponding to an integrated luminosity of 0.33 fb−1. The tau candidates were identified from their decays into electrons, muons or hadronic jets. The number of tau-pair candidates has been compared with the prediction from the Standard Model, where the largest contribution is expected from Bethe-Heitler processes. The total visible cross section was extracted. Standard Model expectations agree well with the measured distributions, also at high invariant mass of the tau pair. <br/

Measurement of dijet photoproduction for events with a leading neutron at HERA

Differential cross sections for dijet photoproduction and this process in association with a leading neutron, e+ + p -> e+ + jet + jet + X (+ n), have been measured with the ZEUS detector at HERA using an integrated luminosity of 40 pb-1. The fraction of dijet events with a leading neutron was studied as a function of different jet and event variables. Single- and double-differential cross sections are presented as a function of the longitudinal fraction of the proton momentum carried by the leading neutron, xL, and of its transverse momentum squared, pT^2. The dijet data are compared to inclusive DIS and photoproduction results; they are all consistent with a simple pion-exchange model. The neutron yield as a function of xL was found to depend only on the fraction of the proton beam energy going into the forward region, independent of the hard process. No firm conclusion can be drawn on the presence of rescattering effects.Comment: 40 pages, 18 figure

Contribution of variable viscosity between domains for the generation and propagation of turbulence

Este trabalho apresenta a comparação qualitativa e quantitativa de dois métodos para a resolução de modelos hidrodinâmicos, fluidodinâmica computacional (CFD) e soluções analíticas, para obter respostas da turbulência à jusante de corpos submersos. Devido a dificuldade de se prever respostas fiéis do comportamento turbulento, o objetivo principal é avaliar os efeitos da variação local da viscosidade cinemática entre os domínios presentes no sistema, sólido e fluido, na discretização das equações que regem o escoamento. Como estratégia de solução, os sólidos são considerados como pseudofluidos de fônons, a fim de justificar a reação no fluido provida desta variação da viscosidade. Pequenas alterações no equacionamento das soluções analíticas apresentaram modificações de resultados expressivas na resolução da turbulência devido ao gradiente gerado pela variação local da viscosidade cinemática.This paper presents a quantitative and qualitative comparison of two methods for solving hydrodynamic models; computational fluid dynamics (CFD) and analytical solutions in order to get answers on the turbulence of downstream submerged bodies. Due to the difficulty of predicting a faithfull turbulent behavior response the main objective is to evaluate the effects of local variation of kinematic viscosity between the domains present in the system, solid and fluid, on the discretization of the equations governing the flow. As a solution strategy, the solids are designed as pseudofluid of phonons in order to justify the reaction provided the atomic excitation generated in the fluid. Small changes in addressing the responses in the analytical results showed significant changes in resolution due to the gradient of the turbulence generated by the local variation of kinematic viscosity

Contribution of variable viscosity between domains for the generation and propagation of turbulence

Este trabalho apresenta a comparação qualitativa e quantitativa de dois métodos para a resolução de modelos hidrodinâmicos, fluidodinâmica computacional (CFD) e soluções analíticas, para obter respostas da turbulência à jusante de corpos submersos. Devido a dificuldade de se prever respostas fiéis do comportamento turbulento, o objetivo principal é avaliar os efeitos da variação local da viscosidade cinemática entre os domínios presentes no sistema, sólido e fluido, na discretização das equações que regem o escoamento. Como estratégia de solução, os sólidos são considerados como pseudofluidos de fônons, a fim de justificar a reação no fluido provida desta variação da viscosidade. Pequenas alterações no equacionamento das soluções analíticas apresentaram modificações de resultados expressivas na resolução da turbulência devido ao gradiente gerado pela variação local da viscosidade cinemática.This paper presents a quantitative and qualitative comparison of two methods for solving hydrodynamic models; computational fluid dynamics (CFD) and analytical solutions in order to get answers on the turbulence of downstream submerged bodies. Due to the difficulty of predicting a faithfull turbulent behavior response the main objective is to evaluate the effects of local variation of kinematic viscosity between the domains present in the system, solid and fluid, on the discretization of the equations governing the flow. As a solution strategy, the solids are designed as pseudofluid of phonons in order to justify the reaction provided the atomic excitation generated in the fluid. Small changes in addressing the responses in the analytical results showed significant changes in resolution due to the gradient of the turbulence generated by the local variation of kinematic viscosity

Fabrication, Mechanical Properties and In-Vitro Behavior of Akermanite Bioceramic

Pure nanocrystalline akermanite (Ca2MgSi2O7) powder was synthesized by mechanical activation with subsequent annealing of talc, calcium carbonate, and silicate powders as the initial materials. Powder samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) techniques. The results showed that pure nanocrystalline akermanite with a crystalline size of 35 nm was synthesized after ball milling the initial powders for 20 h with subsequent annealing at 900 °C for 1 h. Mechanical properties of bulk akermanite samples were studied as well. The results showed that the produced akermanite tablets sintered at 1200 °C for 5 h had a Young’s modulus of 3800 MPa, an ultimate compressive strength of 24.7 MPa, and a density of 2.489 g/cm3. The in-vitro behavior of the produced akermanite was evaluated by soaking the samples in an SBF solution. The results showed that the produced akermanite had the apatite formation ability on its surface and can be a good candidate for bone tissue engineering applications.</jats:p

Fabrication, Mechanical Properties and In-Vitro Behavior of Akermanite Bioceramic

Pure nanocrystalline akermanite (Ca2MgSi2O7) powder was synthesized by mechanical activation with subsequent annealing of talc, calcium carbonate, and silicate powders as the initial materials. Powder samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) techniques. The results showed that pure nanocrystalline akermanite with a crystalline size of 35 nm was synthesized after ball milling the initial powders for 20 h with subsequent annealing at 900 &deg;C for 1 h. Mechanical properties of bulk akermanite samples were studied as well. The results showed that the produced akermanite tablets sintered at 1200 &deg;C for 5 h had a Young&rsquo;s modulus of 3800 MPa, an ultimate compressive strength of 24.7 MPa, and a density of 2.489 g/cm3. The in-vitro behavior of the produced akermanite was evaluated by soaking the samples in an SBF solution. The results showed that the produced akermanite had the apatite formation ability on its surface and can be a good candidate for bone tissue engineering applications