5,307 research outputs found

    Spectral weight redistribution in (LaNiO3)n/(LaMnO3)2 superlattices from optical spectroscopy

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    We have studied the optical properties of four (LaNiO3_3)n_n/(LaMnO3_3)2_2 superlattices (SL) (nn=2, 3, 4, 5) on SrTiO3_3 substrates. We have measured the reflectivity at temperatures from 20 K to 400 K, and extracted the optical conductivity through a fitting procedure based on a Kramers-Kronig consistent Lorentz-Drude model. With increasing LaNiO3_3 thickness, the SLs undergo an insulator-to-metal transition (IMT) that is accompanied by the transfer of spectral weight from high to low frequency. The presence of a broad mid-infrared band, however, shows that the optical conductivity of the (LaNiO3_3)n_n/(LaMnO3_3)2_2 SLs is not a linear combination of the LaMnO3_3 and LaNiO3_3 conductivities. Our observations suggest that interfacial charge transfer leads to an IMT due to a change in valence at the Mn and Ni sites.Comment: Accepted for publication in Phys. Rev. Lett. 5 pages, 5 figure

    The CMCC-INGV Global Ocean Data Assimilation System (CIGODAS)

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    This report summarizes the technical structure and main characteristics of the CMCCINGV Global Ocean Data Assimilation System (CIGODAS) based on a Reduced Order Optimal Interpolation scheme and a coarse resolution Global Ocean Model for the assimilation of temperature and salinity observations. It is intended to be a reference guide for new users who are interested in setting up and running an experiment using this approach and producing estimates of the timevarying, threedimensional state of the global ocean

    Infectious agents in atherosclerotic cardiovascular diseases through oxidative stress

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    Accumulating evidence demonstrates that vascular oxidative stress is a critical feature of atherosclerotic process, potentially triggered by several infectious agents that are considered as risk co-factors for the atherosclerotic cardiovascular diseases (CVDs). C. pneumoniae has been shown to upregulate multiple enzymatic systems capable of producing reactive oxygen species (ROS) such as NADPH oxidase (NOX) and cyclooxygenase in vascular endothelial cells, NOX and cytochrome c oxidase in macrophages as well as nitric oxide synthase and lipoxygenase in platelets contributing to both early and late stages of atherosclerosis. P. gingivalis seems to be markedly involved in the atherosclerotic process as compared to A. actinomycetemcomitans contributing to LDL oxidation and foam cell formation. Particularly interesting is the evidence describing the NLRP3 inflammasome activation as a new molecular mechanism underlying P. gingivalis-induced oxidative stress and inflammation. Amongst viral agents, immunodeficiency virus-1 and hepatitis C virus seem to have a major role in promoting ROS production, contributing, hence, to the early stages of atherosclerosis including endothelial dysfunction and LDL oxidation. In conclusion, oxidative mechanisms activated by several infectious agents during the atherosclerotic process underlying CVDs are very complex and not well-known, remaining, thus, an attractive target for future research

    Tactile Thresholds are Preserved yet Cortical Sensory Function is Impaired in Chronic Non-Specific Low Back Pain Patients

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    Introduction: A substantial amount of evidence points to an alteration in brain structure and function patients with chronic non-specific low back pain (CNSLBP) [1-6]. One interpretation of these findings is that the observed brain changes may represent a disruption of the brain’s representations of the body part and the resultant body perception disturbance may underpin this clinical problem. The current study aimed to investigate sensory dysfunction in CNSLBP. Specifically we aimed to distinguish cortically mediated sensory dysfunction from peripheral dysfunction by comparing simple tactile thresholds with more complex cortically mediated sensory tests Methods: We investigated tactile thresholds (TTH), two point discrimination (TPD) and graphaesthesia over the lumbar spine of 19 CLBP patients and 19 age and sex matched healthy controls as a way of investigating whether CLBP patients present with a perceptual disturbance of their lumbar spine. Differences in performance of the sensory tests was explored using the Mann Whitney U Test and one-way between groups multivariate analysis of variance. Results: We found no difference in tactile threshold between the two groups (P=.0.751). There was a statistically significant difference between controls and LBP for TPD: F(1,36)=10.15, p=.003 and letter error rate: F(1, 36)=6.54 p=0.015. The data indicate that LBP patients had a larger lumbar TPD distance and a greater letter recognition error rate. Discussion: Both TPD and graphaesthesia are dependant on the integrity of the primary sensory cortex [7]. These data support existing findings of perceptual abnormality in chronic back pain [8] and the preservation of tactile thresholds is suggestive of cortical rather than peripheral sensory dysfunction. Amelioration of these abnormalities may present a target for therapeutic intervention

    Phase diagram and optical conductivity of La1.8-xEu0.2SrxCuO4

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    La1.8-xEu0.2SrxCuO4 (LESCO) is the member of the 214 family which exhibits the largest intervals among the structural, charge ordering (CO), magnetic, and superconducting transition temperatures. By using new dc transport measurements and data in the literature we construct the phase diagram of LESCO between x = 0.8 and 0.20. This phase diagram has been further probed in ac, by measuring the optical conductivity {\sigma}1({\omega}) of three single crystals with x = 0.11, 0.125, and 0.16 between 10 and 300 K in order to associate the extra-Drude peaks often observed in the 214 family with a given phase. The far-infrared peak we detect in underdoped LESCO is the hardest among them, survives up to room temperature and is associated with charge localization rather than with ordering. At the CO transition for the commensurate doping x = 0.125 instead the extra-Drude peak hardens and a pseudogap opens in {\sigma}1({\omega}), approximately as wide as the maximum superconducting gap of LSCO.Comment: 6 pages, 6 figure

    Waste reduction in production processes through simulation and VSM

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    Corporate managers often face the need to choose the optimal configurations of production processes to reduce waste. Research has shown that simulation is an effective tool among those conceived to support the manager's decisions. Nevertheless, the use of simulation at the company level remains limited due to the complexity in the design phase. In this context, the Value Stream Map (VSM)-a tool of the Lean philosophy-is here exploited as a link between the strategic needs of the management and the operational aspect of the simulation process in order to approach sustainability issues. The presented approach is divided into two main parts: a set of criteria for expanding the VSM are identified in order to increase the level of details of the represented processes; then, data categories required for the inputs and outputs of each sub-process modeling are defined, including environmental indicators. Specifically, an extended version of the classical VSM (X-VSM), conceived to support process simulation, is here proposed: the X-VSM is used to guide the design of the simulation so that the management decisions, in terms of waste reduction, can be easily evaluated. The proposal was validated on a production process of a large multinational manufacturing company
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