808 research outputs found
A Geometrical Interpretation of Hyperscaling Breaking in the Ising Model
In random percolation one finds that the mean field regime above the upper
critical dimension can simply be explained through the coexistence of infinite
percolating clusters at the critical point. Because of the mapping between
percolation and critical behaviour in the Ising model, one might check whether
the breakdown of hyperscaling in the Ising model can also be intepreted as due
to an infinite multiplicity of percolating Fortuin-Kasteleyn clusters at the
critical temperature T_c. Preliminary results suggest that the scenario is much
more involved than expected due to the fact that the percolation variables
behave differently on the two sides of T_c.Comment: Lattice2002(spin
Microfabricated and multilayered PLGA structure for the development of co-cultured in vitro liver models
One of the main advantages of having an in vitro model is the possibility of reducing toxic effects of drugs on human body and evaluate their response to pharmacological treatments to improve the efficacy of a patient-specific therapy. The limitation of such in vitro model is the use of monolayer hepatocytes cultures that show some problems of protein secretion and hepatic functionality. In order to overcome these drawbacks, we present two innovative multilayer structures based on micro-stamped poly(lactic-co-glycolic acid) (PLGA) structures and hepatocytes and fibroblast co-cultures. In particular, the first model consisted of 1 up to 5 layers of PLGA seeded with the previously cited co-culture, while the second model consisted of various sandwich structures of PLGA functionalised (or not) with collagen and seeded with hepatocytes and/or fibroblasts. A mechanical analysis, contact angle and surface charge density measurements were carried out. After these preliminary tests, a metabolic analysis was performed evaluating glucose consumption and urea and albumin production over a culture period of 11 days. Results showed promising application of these in vitro liver models, in particular considering the field of cirrhotic liver treatment
Low temperature deactivation of Ge heavily n-type doped by ion implantation and laser thermal annealing
International audienceHeavy doping of Ge is crucial for several advanced micro-and optoelectronic applications, but, at the same time, it still remains extremely challenging. Ge heavily n-type doped at a concentration of 1 X 10(20) cm(-3) by As ion implantation and melting laser thermal annealing (LTA) is shown here to be highly metastable. Upon post-LTA conventional thermal annealing As electrically deactivates already at 350 degrees C reaching an active concentration of similar to 4 x 10(19) cm(-3). No significant As diffusion is detected up to 450 degrees C, where the As activation decreases further to similar to 3 x 10(19) cm(-3). The reason for the observed detrimental deactivation was investigated by Atom Probe Tomography and in situ High Resolution X-Ray Diffraction measurements. In general, the thermal stability of heavily doped Ge layers needs to be carefully evaluated because, as shown here, deactivation might occur at very low temperatures, close to those required for low resistivity Ohmic contacting of n-type Ge
The role of obesity and adipokines in coronary microvascular dysfunction: a systematic review and meta-analysis
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Patients with obesity present structural and functional changes in the heart and in the coronary circulation, which ultimately leads to an increased risk of cardiovascular disease. Obesity is associated with a low chronic state of inflammation which seems to be linked to a compromised coronary vasoreactivity, which is shown to be a forerunner and a long-term predictor of clinically relevant cardiovascular events.
Methods
A systematic review was performed by searching PubMed, Embase and Cochrane Library database. Selection criteria were applied leading to the inclusion of studies of any level of evidence published in peer-reviewed journals reporting clinical or preclinical results. Relative data were extracted and critically analysed. PRISMA guidelines were applied and risk of bias was assessed, as well as the methodological quality of the included studies. After this assessment, we excluded all the articles with serious risk of bias and/or low quality. Meta-analysis was conducted on the data collected regarding coronary blood flow (CFR) and hyperemic myocardial blood flow (MBF), while for the other parameters a descriptive analysis was performed.
Results
After applying the described criteria, we included 15 articles on human and animal literature assessed as medium or high quality. The data of 1399 patients were examined, 456 of which with obesity (BMI ≥ 30). A pooled effect size analysis shows that coronary flow reserve (CFR) is significantly reduced in patients with obesity [Random Effect (RE): -47.7%, 95% confidence interval (CI) -80.2% – -15.2%; n = 422]. Increased BMI is associated with reduced CFR. The same trend is found evaluating pharmacological induced stress MBF, which was reduced in patients with obesity [RE: -47.8%, 95% CI -73.7% – -21.8%; n = 409]. Nevertheless, MBF at rest did not show a significant difference in patients with obesity from our analysis [RE: 15%, 95% CI -24% - 53%; n = 409]. Pro-inflammatory adipokines secretion, as leptin and CRP, seems to correlate with a significant decrease of stress-induced MBF and reduced CFR.
Conclusions
Obesity is associated with a significant higher risk of coronary microvascular disfunction, which is reflected by diminished CFR and stress MBF. Systemic inflammation and the imbalance of adipokines related to obesity has been closely linked to a blunt coronary flow. CMD is a pre-clinical heart conditions that often remains undiagnosed. Further evidence is required to clear out the role of Obesity from a molecular point of view on the coronary endothelium
An innovative microprocessor-based system for Human Activity Recognition: A fast and reliable classification algorithm
Vortex critical behavior at the de-confinement phase transition
The de-confinement phase transition in SU(2) Yang-Mills theory is revisited
in the vortex picture. Defining the world sheets of the confining vortices by
maximal center projection, the percolation properties of the vortex lines in
the hypercube consisting of the time axis and two spatial axis are studied.
Using the percolation cumulant, the temperature for the percolation transition
is seen to be in good agreement with the critical temperature of the thermal
transition. The finite size scaling function for the cumulant is obtained. The
critical index of the finite size scaling function is consistent with the index
of the 3D Ising model.Comment: 4 pages, 4 PS figures, using revtex4, paragraph and refs added, typo
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A paraoxonase gene polymorphism, PON 1 (55), as an independent risk factor for increased carotid intima-media tickness in middle-aged women.
Vascular Regenerative Surgery: Promised Land for Tissue Engineers?
Cardiovascular cell therapy is a promising new eld for the development of treatments for cardiovascular diseases, which remain a major cause of mortality around the world. In this review, we highlight the options currently available for the development of speci c cell therapy approaches applied to regeneration of cardiac and vascular tissues. Different cell types have attracted a lot of attention and extensive investigations for the treatment of vascular diseases, including embryonic stem cells, mesenchymal stem cells, induced pluripotent stem cells, and endothelial progenitors. The combination of human cells and increasingly safe and physiologically compliant biomaterials is currently offering an unprecedented opportunity to develop effective cell therapy for either major blood vessels or the microvasculature. Ef cacy and safety of cell therapy are the challenges for the new generation of regenerative medicine scientists determined to develop new remedies for car- diovascular diseases. Here we present the state of the art in this biomedical eld and the options in terms of cell types and biomaterials currently available for cardiovascular cell therapy
Search for the gravity functional form via gaussian processes
The gravity models, for which is the Ricci scalar and is the
trace of the energy-momentum tensor, elevate the degrees of freedom of the
renowned theories, by making the Einstein field equations of the theory
to also depend on . While such a dependence can be motivated by quantum
effects, the existence of imperfect or extra fluids, or even a cosmological
``constant'' which effectively depends on , the formalism can truly surpass
some deficiencies of gravity. As the function is arbitrary,
several parametric models have been proposed {\it ad hoc} in the literature and
posteriorly confronted with observational data. In the present article, we use
gaussian process to construct an model. To apply the gaussian
process we use a series of measurements of the Hubble parameter. We then
analytically obtain the functional form of the function. By construction, this
form, which is novel in the literature, is well-adjusted to cosmological data.
In addition, by extrapolating our reconstruction to redshift , we were
able to constrain the Hubble constant value to $\rm \ km \
s^{-1} \ Mpc^{-1}5\%$ precision. Lastly, we encourage the application
of the functional form herewith obtained to other current problems of
observational cosmology and astrophysics, such as the rotation curves of
galaxies
1.32 ÎĽm InAs/InGaAs/GaAs quantum dot lasers operating at room temperature with low threshold current density
We report on the growth and characterization of low threshold 1.32-μm quantum dots (QDs) laser diodes. The quantum dot active region was optimised to get the highest photoluminescence emission and the lowest Full Width at Half Maximum (FWHM). From samples containing multilayer QDs and using the Limited-Area Photoluminescence (LAPL) technique we have shown that the gain of an N-layer structure is higher than N times that of a single layer. This enhancement is attributed to the increase of the quantum dot density in the upper layers and also to the use of the high growth temperature spacer layer. Broad area laser diodes were processed from the grown samples containing three layers of InAs QDs grown directly on GaAs and capped with 4-nm-thick In x Ga 1-x As layer. Than measurements were performed at room temperature under pulsed excitation. The laser diodes operate at room temperature and emit between 1.29 and 1.32-μm which is beyond the strategic telecommunication wavelength. The characteristic temperature is around 80 K and very stable in the hole range of the operating temperature (from 0 to 90 °C). The internal quantum efficiency is 53% and the modal gain per QD layer was estimated to be ~ 6 cm -1 . For an infinite cavity length a threshold current density of 8 A/cm 2 per QD layer was obtained. From the calculation of the optical confinement of QDs, we have estimated a material gain of 1979 cm -1
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