Crossover to non-Fermi-liquid spin dynamics in cuprates

The antiferromagnetic spin correlation function $S_{\bf Q}$, the staggered spin susceptibility $\chi_{\bf Q}$ and the energy scale $\omega_{FL}=S_{\bf Q}/\chi_{\bf Q}$ are studied numerically within the t-J model and the Hubbard model, as relevant to cuprates. It is shown that $\omega_{FL}$, related to the onset of the non-Fermi-liquid spin response at $T>\omega_{FL}$, is very low in the regime below the 'optimum' hole doping $c_h < c_h^* \sim 0.16$, while it shows a steep increase in the overdoped regime. A quantitative analysis of NMR spin-spin relaxation-rate $1/T_{2G}$ for various cuprates reveals a similar behavior, indicating on a sharp, but continuous, crossover between a Fermi-liquid and a non-Fermi-liquid behavior as a function of doping.Comment: 4 pages, 4 figures. Submitted to PR

Double dispersion of the magnetic resonant mode in cuprates

The magnetic excitation spectra in the vicinity of the resonant peak, as observed by inelastic neutron scattering in cuprates, are studied within the memory-function approach. It is shown that at intermediate doping the superconducting gap induces a double dispersion of the peak, with an anisotropy rotated between the downward and upward branch. Similar behavior, but with a spin-wave dispersion at higher energies, is obtained for the low-doping case assuming a large pairing pseudogap.Comment: 4 LaTeX pages, 4 figure

Puckering Free Energy of Pyranoses: an NMR and Metadynamics--Umbrella Sampling Investigation

We present the results of a combined metadynamics--umbrella sampling investigation of the puckered conformers of pyranoses described using the gromos 45a4 force field. The free energy landscape of Cremer--Pople puckering coordinates has been calculated for the whole series of alpha and beta aldohexoses, showing that the current force field parameters fail in reproducing proper puckering free energy differences between chair conformers. We suggest a modification to the gromos 45a4 parameter set which improves considerably the agreement of simulation results with theoretical and experimental estimates of puckering free energies. We also report on the experimental measurement of altrose conformers populations by means of NMR spectroscopy, which show good agreement with the predictions of current theoretical models

Traumatic brain injury and NADPH oxidase: A deep relationship

Traumatic brain injury (TBI) represents one of the major causes of mortality and disability in the world. TBI is characterized by primary damage resulting from the mechanical forces applied to the head as a direct result of the trauma and by the subsequent secondary injury due to a complex cascade of biochemical events that eventually lead to neuronal cell death. Oxidative stress plays a pivotal role in the genesis of the delayed harmful effects contributing to permanent damage. NADPH oxidases (Nox), ubiquitary membrane multisubunit enzymes whose unique function is the production of reactive oxygen species (ROS), have been shown to be a major source of ROS in the brain and to be involved in several neurological diseases. Emerging evidence demonstrates that Nox is upregulated after TBI, suggesting Nox critical role in the onset and development of this pathology. In this review, we summarize the current evidence about the role of Nox enzymes in the pathophysiology of TBI

Traumatic brain injury and NADPH oxidase: A deep relationship

Traumatic brain injury (TBI) represents one of the major causes of mortality and disability in the world. TBI is characterized by primary damage resulting from the mechanical forces applied to the head as a direct result of the trauma and by the subsequent secondary injury due to a complex cascade of biochemical events that eventually lead to neuronal cell death. Oxidative stress plays a pivotal role in the genesis of the delayed harmful effects contributing to permanent damage. NADPH oxidases (Nox), ubiquitary membrane multisubunit enzymes whose unique function is the production of reactive oxygen species (ROS), have been shown to be a major source of ROS in the brain and to be involved in several neurological diseases. Emerging evidence demonstrates that Nox is upregulated after TBI, suggesting Nox critical role in the onset and development of this pathology. In this review, we summarize the current evidence about the role of Nox enzymes in the pathophysiology of TBI

Mesoscopic simulations of the counterion-induced electroosmotic flow - a comparative study

We present mesoscopic simulations of the counterion-induced electroosmotic flow in different electrostatic coupling regimes. Two simulation methods are compared, Dissipative Particle Dynamics (DPD) and coupled Lattice-Boltzmann/Molecular Dynamics (LB/MD). A general mapping scheme to match DPD to LB/MD is developed. For the weak-coupling regime, analytic expressions for the flow profiles in the presence of partial-slip as well as no-slip boundary conditions are derived from the Poisson-Boltzmann and Stokes equations, which are in good agreement with the numerical results. The influence of electrofriction and partial slip on the flow profiles is discussed.Comment: 10 pages, 8 figures, 3 tables, additional references and minor changes in the tex

Correlation of test results and influence of a mass balance constraint on risks in conformity assessment of a substance or material

When components of a substance or material are subject to a mass balance constraint, test results of the components’ contents are intrinsically correlated because of the constraint. This so-called ‘spurious’ correlation is observed in addition to possible metrologically-related correlation of test results, and natural and/or technological correlation of the components’ contents. Such correlations may influence understanding of test results and evaluation of risks of false decisions, due to measurement uncertainty, in conformity assessment of the substance or material. The objective of the present paper is the development of a technique for appropriate evaluation of the risks. A Bayesian multivariate approach to evaluate the conformance probability of materials or objects and relevant risks is discussed for different scenarios of the data modelling, taking into account all observed correlations. A Monte Carlo method, including the mass balance constraint, written in the R programming environment, is provided for the necessary calculations

The contribution of major risk factors and job strain to occupational class differences in coronary heart disease incidence: the MONICA Brianza and PAMELA population-based cohorts

Objectives We investigated the contribution of major coronary heart disease (CHD) risk factors and job strain to occupational class differences in CHD incidence in a pooled-cohort prospective study in northern Italy. Methods 2964 men aged 25-74 from four northern Italian population-based cohorts were investigated at baseline and followed for first fatal or non-fatal CHD event (171 events). Standardised procedures were used for baseline risk factor measurements, follow-up and validation of CHD events. Four occupational classes were derived from the Erikson-Goldthorpe-Portocarero social class scheme: higher and lower professionals and administrators, non-manual workers, skilled and unskilled manual workers, and the self-employed. HRs were estimated with Cox models. Results Among CHD-free subjects, with non-manual workers as the reference group, age-adjusted excess risks were found for professionals and administrators (+84%, p=0.02), the self-employed (+72%, p=0.04) and manual workers (+63%, p=0.04). The relationship was consistent across different CHD diagnostic categories. Adjusting for major risk factors only slightly reduced the reported excess risks. In a sub-sample of currently employed subjects, adjusting for major risk factors, sport physical activity and job strain reduced the excess risk for manual workers (relative change = -71.4%) but did not substantially modify the excess risks of professionals and administrators and the self-employed. Conclusions In our study, we found higher CHD incidence rates for manual workers, professionals and administrators, and the self-employed, compared to non-manual workers. When the entire spectrum of job categories is considered, the job strain model helped explain the CHD excess risk for manual workers but not for other occupational classes