374 research outputs found
High-Order Numerical Method for 1D Non-local Diffusive Equation
In this paper we present a non-local numerical scheme based on the Local
Discontinuous Galerkin method for a non-local diffusive partial differential
equation with application to traffic flow. In this model, the velocity is
determined by both the average of the traffic density as well as the changes in
the traffic density at a neighborhood of each point. We discuss nonphysical
behaviors that can arise when including diffusion, and our measures to prevent
them in our model. The numerical results suggest that this is an accurate
method for solving this type of equation and that the model can capture desired
traffic flow behavior. We show that computation of the non-local convolution
results in complexity, but the increased computation time
can be mitigated with high-order schemes like the one proposed.Comment: 17 pages and 8 figure
Regenerative potential of DPSCs and revascularization. direct, paracrine or autocrine effect?
A new source of mesenchymal stem cells has recently been discovered, the so-called dental pulp derived stem cells (DPSCs) which therefore could represent potentially tools for regenerative medicine. DPSC originate from the neural crest and are physiologically involved in dentin homeostasis; moreover, they contribute to bone remodeling and differentiation into several tissues including cartilage, bone, adipose and nervous tissues. DPSCs have also been shown to influence the angiogenesis process, for example through the release of secretory factors or by differentiating into vascular and/or perivascular cells. Angiogenesis, that has a pivotal role in tissue regeneration and repair, is defined as the formation of new vessels from preexisting vessels and is mediated by mutual and reciprocal interactions between endothelial cells and perivascular cells. It is also known that co-cultures of perivascular and endothelial cells (ECs) can form a vascular network in vitro and also in vivo. Since DPSCs seem to have characteristics similar to pericytes, understanding the possible mechanism of interaction between DPSCs and ECs during neo-angiogenesis is dramatically important for the development of advanced clinical application in the field of regeneration. Graphical abstract: [Figure not available: see fulltext.
Elevated alanine aminotransferase in blood donors: role of different factors and multiple viral infections.
Many different aetiological agents stimulate alanine aminotransferase (ALT) production. Viral markers and other aetiologies were investigated in 2166 individuals, randomly selected from 10 000 consecutive blood donors. Elevation of ALT was found in 10.8% of subjects. Grouping donors according to ALT level and correlating with, respectively, hepatitis B core antibody (HBcAb), cytomegalovirus antibody alone, or associated with HBcAb, showed similar findings (high ALT 11.1%, normal 11.6%; high 85.4%, normal 81.4%; high 10.2%, normal 11.0%, respectively). Hepatitis C virus (HCV) antibody was found to be significantly associated with elevated ALT levels (high 1.7%, normal 0.26%). Other causes of ALT elevation were alcohol abuse (17%), obesity (25%) and dyslipidaemia (38%), but in 11% there was no obvious aetiology. Although HCV is a rare cause of elevated ALT in blood donors, it seems to be the only virus, among those tested, to account for liver damage. This may be due to the non-protective role of HCV antibody, the low specificity of ALT, or the pathogenic role of uninvestigated viruses
Synthesis, Structural, Magnetic and Computational Studies of a One-Dimensional Ferromagnetic Cu(II) Chain Assembled from a New Schiff Base Ligand
A new asymmetrically substituted ONOO Schiff base ligand N-(2′-hydroxy-1′-naphthylidene)-3-amino-2-naphthoic acid (nancH2) was prepared from the condensation of 2–hydroxy–1–naphthaldehyde and 3–amino–2–naphthoic acid. nancH2 reacts with Cu2(O2CMe)4·2H2O in the presence of Gd(O2CMe)3·6H2O to afford a uniform one-dimensional homometallic chain, [CuII(nanc)]n (1). The structure of 1 was elucidated via single crystal X-ray diffraction studies, which revealed that the Cu(II) ions adopt distorted square planar geometries and are coordinated in a tridentate manner by an [ONO] donor set from one nanc2− ligand and an O− of a bridging carboxylate group from a second ligand. The bridging carboxylato group of the nanc2− ligand adopts a syn, anti-η1:η1:μ conformation linking neighboring Cu(II) ions, forming a 1D chain. The magnetic susceptibility of 1 follows Curie–Weiss law in the range 45–300 K (C = 0.474(1) emu K mol-1, θ = +7.9(3) K), consistent with ferromagnetic interactions between S = ½ Cu(II) ions with g = 2.248. Subsequently, the data fit well to the 1D quantum Heisenberg ferromagnetic (QHFM) chain model with g = 2.271, and J = +12.3 K. DFT calculations, implementing the broken symmetry approach, were also carried out on a model dimeric unit extracted from the polymeric chain structure. The calculated exchange coupling via the carboxylate bridge (J = +13.8 K) is consistent with the observed ferromagnetic exchange between neighbouring Cu(II) centres. © 2023 by the authors.
This article belongs to the Special Issue Coordination Chemistry: Current Developments and Future Perspectives — a Themed Issue in Honor of Professor Spyros P. Perlepes on the Occasion of His 70th Birthday)
This article contains supplementary material. It is available for download as a supplementary file
What kind of hepatitis
Finding one major hepatotropic virus may not be enough to identify the aetiology of liver disease when risk factors are present, particularly in patients with past or present infection with other viral agents, or chronic liver disease. The pathogenic process in these cases is often complex. In the five cases we report, acute hepatitis (initiated by halothane, cytomegalovirus or Epstein-Barr virus) preceded the reactivation of hepatitis B infection, and these events occurred in patients with chronic hepatitis C infection. Each case demonstrates how several viruses can be implicated in the development of hepatitis, either as single agents or via cross-activation of T cells. The nosography of hepatitis, therefore, and the optimum therapeutic choices, can puzzle the clinical team
A Presence- and Performance-Driven Framework to Investigate Interactive Networked Music Learning Scenarios
Cooperative music making in networked environments has been subject of extensive research, scientific and artistic. Networked music performance (NMP) is attracting renewed interest thanks to the growing availability of effective technology and tools for computer-based communications, especially in the area of distance and blended learning applications. We propose a conceptual framework for NMP research and design in the context of classical chamber music practice and learning: presence-related constructs and objective quality metrics are used to problematize and systematize the many factors affecting the experience of studying and practicing music in a networked environment. To this end, a preliminary NMP experiment on the effect of latency on chamber music duos experience and quality of the performance is introduced. The degree of involvement, perceived coherence, and immersion of the NMP environment are here combined with measures on the networked performance, including tempo trends and misalignments from the shared score. Early results on the impact of temporal factors on NMP musical interaction are outlined, and their methodological implications for the design of pedagogical applications are discussed
Cooperative Driving for Speed Harmonization in Mixed-Traffic Environments
Autonomous driving systems present promising methods for congestion
mitigation in mixed autonomy traffic control settings. In particular, when
coupled with even modest traffic state estimates, such systems can plan and
coordinate the behaviors of automated vehicles (AVs) in response to observed
downstream events, thereby inhibiting the continued propagation of congestion.
In this paper, we present a two-layer control strategy in which the upper layer
proposes the desired speeds that predictively react to the downstream state of
traffic, and the lower layer maintains safe and reasonable headways with
leading vehicles. This method is demonstrated to achieve an average of over 15%
energy savings within simulations of congested events observed in Interstate 24
with only 4% AV penetration, while restricting negative externalities imposed
on traveling times and mobility. The proposed strategy that served as the
"speed planner" was deployed on 100 AVs in a massive traffic experiment
conducted on Nashville's I-24 in November 2022
Comparison of the economic impact of different wind power forecast systems for producers
Deterministic forecasts of wind production for the next 72 h at a single
wind farm or at the regional level are among the main end-users requirement.
However, for an optimal management of wind power production and distribution
it is important to provide, together with a deterministic prediction, a
probabilistic one. A deterministic forecast consists of a single value for
each time in the future for the variable to be predicted, while
probabilistic forecasting informs on probabilities for potential future
events. This means providing information about uncertainty (i.e. a forecast
of the PDF of power) in addition to the commonly provided single-valued
power prediction. A significant probabilistic application is related to the
trading of energy in day-ahead electricity markets. It has been shown that,
when trading future wind energy production, using probabilistic wind power
predictions can lead to higher benefits than those obtained by using
deterministic forecasts alone. In fact, by using probabilistic forecasting
it is possible to solve economic model equations trying to optimize the
revenue for the producer depending, for example, on the specific penalties
for forecast errors valid in that market. In this work we have applied a
probabilistic wind power forecast systems based on the "analog ensemble"
method for bidding wind energy during the day-ahead market in the case of a
wind farm located in Italy. The actual hourly income for the plant is
computed considering the actual selling energy prices and penalties
proportional to the unbalancing, defined as the difference between the
day-ahead offered energy and the actual production. The economic benefit of
using a probabilistic approach for the day-ahead energy bidding are
evaluated, resulting in an increase of 23% of the annual income for a
wind farm owner in the case of knowing "a priori" the future energy
prices. The uncertainty on price forecasting partly reduces the economic
benefit gained by using a probabilistic energy forecast system
New 3,4-seco ent-kaurenes from Croton caracasana flowers
Two new 3,4-seco- ent-kaurenes, caracasine (1) and caracasine acid (2), were isolated from non-polar extracts of the flowers of Croton caracasana (Euphorbiaceae), together with six known terpenes, stigmasterol (4), stigmastenone (5), 2,6-dimethylocta-3,7-diene-2, 6-diol (6), spathulenol (7), caryophyllene oxide (8), and aromadendrene (9), and the flavonoid tribuloside (10). The chemical structures were determined by spectroscopic means and chemical correlations. All isolated compounds are being described for the first time for this species
- …