Uniform semiclassical wave function for coherent 2D electron flow

We find a uniform semiclassical (SC) wave function describing coherent branched flow through a two-dimensional electron gas (2DEG), a phenomenon recently discovered by direct imaging of the current using scanned probed microscopy. The formation of branches has been explained by classical arguments, but the SC simulations necessary to account for the coherence are made difficult by the proliferation of catastrophes in the phase space. In this paper, expansion in terms of "replacement manifolds" is used to find a uniform SC wave function for a cusp singularity. The method is then generalized and applied to calculate uniform wave functions for a quantum-map model of coherent flow through a 2DEG. Finally, the quantum-map approximation is dropped and the method is shown to work for a continuous-time model as well.Comment: 9 pages, 7 figure

Interaction between genes and lifestyle factors on obesity.

Obesity originates from a failure of the body-weight control systems, which may be affected by changing environmental influences. Basically, the obesity risk depends on two important mutually-interacting factors: (1) genetic variants (single-nucleotide polymorphisms, haplotypes); (2) exposure to environmental risks (diet, physical activity etc.). Common single-nucleotide polymorphisms at candidate genes for obesity may act as effect modifiers for environmental factors. More than 127 candidate genes for obesity have been reported and there is evidence to support the role of twenty-two genes in at least five different populations. Gene-environment interactions imply that the synergy between genotype and environment deviates from either the additive or multiplicative effect (the underlying model needs to be specified to appraise the nature of the interaction). Unravelling the details of these interactions is a complex task. Emphasis should be placed on the accuracy of the assessment methods for both genotype and lifestyle factors. Appropriate study design (sample size) is crucial in avoiding false positives and ensuring that studies have enough power to detect significant interactions, the ideal design being a nested case-control study within a cohort. A growing number of studies are examining the influence of gene-environmental interactions on obesity in either epidemiological observational or intervention studies. Positive evidence has been obtained for genes involved in adiposity, lipid metabolism or energy regulation such as PPARgamma2 (Pro12Ala), beta-adrenoceptor 2 (Gln27Glu) or uncoupling proteins 1, 2 and 3. Variants on other genes relating to appetite regulation such as melanocortin and leptin receptors have also been investigated. Examples of some recently-identified interactions are discussed

A traditional mediterranean diet effectively reduces inflammation and improves cardiovascular health

Chrysohoou et al. fifteen years ago, showed in an elegant analysis nested within the ATTICA study [1] that a dietary score reflecting adherence to the traditional Mediterranean diet (MedDiet) was inversely associated with plasma biomarkers of low-grade inflammation. Specifically, participants in the highest tertile of adherence to the MedDiet presented 20% lower levels of highly-sensitive C reactive protein (hs-CRP), 17% lower levels of interleukin-6 (IL-6), and 14% lower white blood cell counts. This was an observational study that could be affected by residual confounding and other potential imperfections. However, another similar study, this time nested within the Nurses Cohort in the USA [2], assessed hs-CRP, IL-6, E-selectin, soluble intercellular cell adhesion molecule 1, and soluble vascular cell adhesion molecule 1 and found that better adherence to the MedDiet was also associated with a reduction in inflammatory biomarker concentrations, with relative reductions of 24% in hs-CRP, 16% in IL-6, and 13% in E-selectin concentrations [2]. These well conducted observational studies were subsequently confirmed by a randomized clinical trial (the pilot study of the PREDIMED (PREvención con DIeta MEDiterránea) trial) where we were able to show that an intervention with 2 MedDiets maintained during 3 months was able to reduce hs-CRP, IL-6 (in both cases) and adhesion molecules compared to a low-fat diet [3]. However, hs-CRP was reduced only when the MedDiet was supplemented with polyphenol-rich extra-virgin olive oil, but not with nuts

Bifurcations and Slow-Fast Analysis in a Cardiac Cell Model for Investigation of Early Afterdepolarizations

In this study, we teased out the dynamical mechanisms underlying the generation of arrhythmogenic early afterdepolarizations (EADs) in a three-variable model of a mammalian ventricular cell. Based on recently published studies, we consider a 1-fast, 2-slow variable decomposition of the system describing the cellular action potential. We use sweeping techniques, such as the spike-counting method, and bifurcation and continuation methods to identify parametric regions with EADs. We show the existence of isolas of periodic orbits organizing the different EAD patterns and we provide a preliminary classification of our fast-slow decomposition according to the involved dynamical phenomena. This investigation represents a basis for further studies into the organization of EAD patterns in the parameter space and the involved bifurcations

Mediterranean diet as the ideal model for preventing non-alcoholic fatty liver disease (NAFLD)

The prevalence of nonalcoholic fatty liver disease (NAFLD) has dramatically increased in the 2–3 last decades and it represents the most frequent global cause of liver disease, affecting 25% to 45% of adults in most studies (1). The worldwide elevation in the population rates of NAFLD has come in parallel with rising unprecedented pandemics of obesity and diabetes. There is no specific medication for NAFLD and dietary/lifestyle modifications are the main foundations for the treatment of NAFLD. They are also very likely to be effective for its primary prevention. In this context, a dietary pattern that meets most requirements to become the ideal model for the prevention of NAFLD is the traditional Mediterranean diet (2). In addition to the potential for preventing NAFLD, the Mediterranean diet has sufficiently demonstrated its great ability to improve cardiovascular health. The accrual of prospective and well conducted studies showing cardiovascular benefits associated with better adherence to a high-quality food pattern is superior for the traditional Mediterranean food pattern than for any other dietary pattern (3)

Prevención cardiovascular y de la osteoporosis con terapia hormonal sustitutiva

Se recomienda actualmente que todo médico -sea cual sea su especialidad- aproveche la oportunidad que supone la atención clínica a cualquier mujer postmenopáusica o que se halle en torno a la menopausia para aconsejarle acerca de los beneficios y riesgos que supone la terapia hormonal sustitutiva (THS) con estrógenos y progesterona. Una vez que sea adecuadamente informada de estos beneficios y riesgos, debe ser la propia mujer quien decida si va a iniciar o no esta terapia, teniendo en cuenta no sólo su propio perfil de riesgo sino también sus preferencias. Los beneficios más claros se refieren a la reducción del riesgo de osteoporosis y de fracturas, así como al control y prevención de algunos síntomas frecuentes en la menopausia. Para prevenir la osteoporosis se requiere un uso continuado de IaTHS. También existen cada vez más argumentos que sugieren una reducción del riesgo de un primer episodio coronario. No obstante, no hay pruebas de que laTHS sea útil en la prevención secundaria de la cardiopatía isquémica o aporte alguna protección frente a los accidentes cerebrovasculares. Las desventajas más importantes de la THS se refieren a un mayor riesgo de hiperplasia de endometrio y de cáncer endometrial cuando se usan estrógenos solos, sin combinarlos con progestágenos. También existe un pequeño incremento del riesgo de cáncer de mama cuando se prolonga la THS, también cuando se asocian progestágenos

Evaluation of pressure and temperature effect on the structure and properties of Ca2.93Sr0.07Co4O9 ceramic materials

In this work, the effect of hot-pressing conditions on the performances of Sr-doped Ca3Co4O9 materials has been investigated. The samples were prepared from attrition milled precursors, which reduced the processing time. Samples were hot-pressed at temperatures (T) between 800 and 900 °C and pressures (P) from 51 to 71 MPa. The out-of-plane X-ray diffraction (XRD) showed that all samples are formed by the thermoelectric phase, with a good grain orientation which is improved with T, and P, as demonstrated by their Lotgering factor. The observations through Scanning Electron Microscopy (SEM) have revealed that grain sizes and orientation are enhanced with T, and P, as well as density through Archimedes''s method. All these trends are reflected in the flexural strength and microhardness. The electrical resistivity is lower when the T, or P, is increased, reaching 6.4 mO cm for samples processed at 900 °C and 71 MPa, which is about the best reported values in the literature. On the other hand, contrarily to the expected results, they also showed the highest S values, 182 µV/K, which are similar to the best reported values for highly dense textured materials. Thermal conductivity values do not follow a regular evolution with the hot-pressing conditions, probably due to internal stresses, reaching the lowest values at 800 °C in samples processed at 800 °C and 51 MPa (1.51 W/(K*m)) or 900 °C and 61 MPa (1.53 W/(K*m)). Consequently, the highest ZT values have been determined in samples processed at 900 °C and 61 MPa (0.35) which is higher than the best reported values in literature for bulk textured samples, to the best of our knowledge. © 2021 The Author

Influence of a commercial antithrombotic filter on the caval blood flow during neutra and valsalva maneuver

Anticoagulants are the treatment of choice for pulmonary embolism. When these fail or are contraindicated, vena cava filters are effective devices for preventing clots from the legs from migrating to the lung. Many uncertainties exist when a filter is inserted, especially during physiological activity such as normal breathing and the Valsalva maneuver. These activities are often connected with filter migration and vena cava damage due to the various related vein geometrical configurations. In this work, we analyzed the response of the vena cava during normal breathing and Valsalva maneuver, for a healthy vena cava and after insertion of a commercial Günther-Tulip® filter. Validated computational fluid dynamics (CFD) and patient specific data are used for analyzing blood flow inside the vena cava during these maneuvers. While during normal breathing, the vena cava flow can be considered almost stationary with a very low pressure gradient, during Valsalva the extravascular pressure compresses the vena cava resulting in a drastic reduction of the vein section, a global flow decrease through the cava but increasing the velocity magnitude. This change in the section is altered by the presence of the filter which forces the section of the vena cava before the renal veins to keep open. The effect of the presence of the filter is investigated during these maneuvers showing changes in wall shear stress and velocity patterns