520 research outputs found
Crossover to non-Fermi-liquid spin dynamics in cuprates
The antiferromagnetic spin correlation function , the staggered
spin susceptibility and the energy scale are studied numerically within the t-J model and the Hubbard
model, as relevant to cuprates. It is shown that , related to the
onset of the non-Fermi-liquid spin response at , is very low in
the regime below the 'optimum' hole doping , while it
shows a steep increase in the overdoped regime. A quantitative analysis of NMR
spin-spin relaxation-rate 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
Stability study and uncertainty evaluation of CO2 certified reference materials for greenhouse gases monitoring
The continuous rising in the concentration of carbon dioxide (CO2) in the atmosphere is one of the main causes of
the increase in the greenhouse effect and global warming. To monitor the alarming scenario and to provide
Governments and decision makers with reliable emission data, gaseous certified reference materials (CRMs) at
atmospheric CO2 amount fraction are needed. This paper describes two independent metrological traceability
paths established at INRiM for the preparation of this kind of CRMs. The aim of this publication is to show a
method for evaluating the uncertainty associated with CRM stability and to demonstrate that there is no significant
trend in the results over time. Such CRMs are produced as an intermediate step towards the development
of novel generation CRMs certified also for the isotopic composition
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
- …