We tested the hypothesis that long-term caffeine intake prevents the development of insulin resistance and hypertension in two pathological animal models: the high-fat (HF) and the high-sucrose (HSu) diet rat. We used six groups of animals: control; caffeine-treated (Caff; 1 g/l in drinking water during 15 d); HF; caffeine-treated HF (HFCaff); HSu; caffeine-treated HSu (HSuCaff). Insulin sensitivity was assessed using the insulin tolerance test. Blood pressure, weight gain, visceral fat, hepatic glutathione, plasma caffeine, insulin and NO, and serum NEFA and catecholamines were measured. Caffeine reversed insulin resistance and hypertension induced by both the HF and HSu diets. In the HF-fed animals caffeine treatment restored fasting insulin levels to control values and reversed increased weight gain and visceral fat mass. In the HSu group, caffeine reversed fasting hyperglycaemia and restored NEFA to control values. There were no changes either in plasma NO or in hepatic glutathione levels. In contrast, caffeine totally prevented the increase in serum catecholamines induced by HF and HSu diets. To test the hypothesis that inhibition of the sympathetic nervous system prevents the development of diet-induced insulin resistance we administered carvedilol, an antagonist of b1, b2 and also a1 adrenoceptors, to HF and HSu rats. Carvedilol treatment fully prevented diet-induced insulin resistance and hypertension, mimicking the effect of caffeine. We concluded that long-term caffeine intake prevented the development of insulin resistance and hypertension in HF and HSu models and that this effect was related to a decrease in circulating catecholamines.

Abstract:We study the SU(3) gauge theory with twelve flavours of fermions in the fundamental representation as a prototype of non-Abelian gauge theories inside the conformal window. Guided by the pattern of underlying symmetries, chiral and conformal, we analyze the two-point functions theoretically and on the lattice, and determine the finite size scaling and the infinite volume fermion mass dependence of the would-be hadron masses. We show that the spectrum in the Coulomb phase of the system can be described in the context of a universal scaling analysis and we provide the nonperturbative determination of the fermion mass anomalous dimension γ * = 0.235(46) at the infrared fixed point. We comment on the agreement with the four-loop perturbative prediction for this quantity and we provide a unified description of all existing lattice results for the spectrum of this system, them being in the Coulomb phase or the asymptotically free phase. Our results corroborate the view that the fixed point we are studying is not associated to a physical singularity along the bare coupling line and estimates of physical observables can be attempted on either side of the fixed point. Finally, we observe the restoration of the U(1) axial symmetry in the two-point functions.

In this work we revisit the MIT bag model to describe quark matter within both the usual Fermi-Dirac and the Tsallis statistics. We verify the effects of the non-additivity of the latter by analysing two different pictures: the first order phase transition of the QCD phase diagram and stellar matter properties. While, the QCD phase diagram is visually affected by the Tsallis statistics, the resulting effects on quark star macroscopic properties are barely noticed.

We study the SU(3) gauge theory with N f = 12 flavors in the fundamental representation by use of lattice simulations with staggered fermions. With a non-improved action we observe a chiral zero-temperature (bulk) transition separating a region at weak coupling, where chiral symmetry is realized, from a region at strong coupling where chiral symmetry is broken. With improved actions, a more complicated pattern emerges, and in particular two first order transitions in the chiral limit appear. We observe that at sufficiently strong coupling the next-to-nearest neighbor terms of the improved lattice action are no longer irrelevant and can indeed modify the pattern observed without improvement. Baryon number conservation can be realized in an unusual way, allowing for an otherwise prohibited oscillating term in the pseudoscalar channel. We discuss the phenomenon by means of explicit examples borrowed from statistical mechanics. Finally, these observations can also be useful when simulating other strongly coupled systems on the lattice, such as graphene.

We discuss our results on QCD with a number of fundamental fermions ranging from zero to sixteen. These theories exhibit a wide array of fascinating phenomena which have been under close scrutiny, especially in recent years, first and foremost is the approach to conformality. To keep this review focused, we have chosen scale generation, or lack thereof as a guiding theme, however the discussion will be set in the general framework of the analysis of the phases and phase transitions of strong interactions at zero and nonzero temperature. I. ADDING MATTER : QCD WITH AN ARBITRARY FLAVOR NUMBERUsual QCD dynamics is characterized by spontaneous symmetry breaking and dynamical mass generation, with the associated scale Λ QCD . However, when the number of flavors exceeds a critical number, an infra-red fixed point (IRFP) appears and prevents the coupling from growing large enough to break chiral symmetry. The theory is then scale invariant -even conformal invariant. In the intermediate region, the coupling 'walks' rather than runs between two typical scales -this is the phenomena of scale separation for which our results provide a preliminary evidence. From a general field theory viewpoint, the analysis of the phase diagram of strong interactions as a function of the number of flavor adds to our knowledge of the theoretical basis of strong interactions and their fundamental mechanisms. From a phenomenological viewpoint, this study deals with a class of models which might play a relevant role in model building beyond the standard model (BSM) [1][2][3][4][5][6], which explain the origin of mass using strong coupling mechanisms realized in QCD with a large number of flavors. All these topics are under active scrutiny both theoretically and experimentally A. ConformalityConformal invariance is anticipated to emerge in the non-Abelian gauge theory with many species (flavors) of fermions [59][60][61][62][63]. This is due to the IRFP for N f > N * f at a coupling which is not strong enough to break chiral symmetry: a second zero of the two-loop beta-function of a non-Abelian gauge theory implies, at least perturbatively, the appearance of IRFP conformal symmetry [59,60]. In color SU(3) gauge theory with N f massless fundamental fermions, the second zero appears at N f 8.05, before the loss of asymptotic freedom (LAF) B. Pre-conformalityThe direct inspection of theories at fixed N f is often inconclusive, especially close to the expected threshold N * f . An alternative approach to establish the existence of the conformal window is to (try to) observe directly the approach to conformality by monitoring the evolution of the results obtained in the broken phase as a function of N f .Moreover, the pre-conformal dynamics at flavor numbers just before the onset of conformal invariance might serve as a paradigm for the BSM model buildings that invokes non-perturbative mechanisms of electroweak symmetry breaking [3][4][5][6]. In such pre-conformal region, the coupling should vary little -should walk -with the scale, at