4,966 research outputs found
Spectral weight redistribution in (LaNiO3)n/(LaMnO3)2 superlattices from optical spectroscopy
We have studied the optical properties of four
(LaNiO)/(LaMnO) superlattices (SL) (=2, 3, 4, 5) on
SrTiO 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
LaNiO 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 (LaNiO)/(LaMnO) SLs is not a linear
combination of the LaMnO and LaNiO 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)
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
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
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
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
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
Global ocean re-analyses for climate applications
One of the main objectives of the global ocean modelling activities
at Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC)
is the production of global ocean re-analyses over multidecadal
periods to reconstruct the state of the ocean and the large scale cir-
culation over the recent past. The re-analyses are used for climate applications
and for the assessment of the benefits of assimilating
ocean
observations on seasonal and longer predictions.
Here
we present the main characteristics of an optimal interpola-
tion
based assimilation system used to produce a set of global ocean
re-analyses
validated against a set of high quality in situ observa-
tions
and independent data. Differences among the experiments
of
the set are analyzed in terms of improvements in the method
used
to assimilate the data and the quality of observations them-
selves.
For example, the integrated ocean heat content, which can
be
taken as an indicator of climate changes, is examined to detect
possible
sources of uncertainty of its long-term changes. Global and
basin
scale upper ocean heat content exhibits warming trends over
the
last few decades that still depend in a significant way on the
assimilated
observations and the formulation of the background
covariances.
However, all the re-analyses show a global warming
trend
of the oceanic uppermost 700 m over the last five decades
that
falls within the range of the most recent observation-based
estimates.
The largest discrepancies between our estimates and
observational
based ones are confined in the upwelling regions of
the
PacificandAtlanticOceans.Finally,theresultsshow that the climatological
heat and salt transports as a function of latitude also
fall
within the range of the estimates based on observations and
atmospheric
re-analyses
HyBIS: Windows Guest Protection through Advanced Memory Introspection
Effectively protecting the Windows OS is a challenging task, since most
implementation details are not publicly known. Windows has always been the main
target of malwares that have exploited numerous bugs and vulnerabilities.
Recent trusted boot and additional integrity checks have rendered the Windows
OS less vulnerable to kernel-level rootkits. Nevertheless, guest Windows
Virtual Machines are becoming an increasingly interesting attack target. In
this work we introduce and analyze a novel Hypervisor-Based Introspection
System (HyBIS) we developed for protecting Windows OSes from malware and
rootkits. The HyBIS architecture is motivated and detailed, while targeted
experimental results show its effectiveness. Comparison with related work
highlights main HyBIS advantages such as: effective semantic introspection,
support for 64-bit architectures and for latest Windows (8.x and 10), advanced
malware disabling capabilities. We believe the research effort reported here
will pave the way to further advances in the security of Windows OSes
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