GMOR-like relation in IR-conformal gauge theories

A generalization of the GMOR relation to the case of infrared-conformal gauge theories is discussed. The starting point is the chiral Ward identity connecting the isovector pseudoscalar susceptibility to the chiral condensate, in a mass-deformed theory. A renormalization-group analysis shows that the pseudoscalar susceptibility is not saturated by the lightest state, but a contribution from the continuum part of the spectrum survives in the chiral limit. The computation also shows how infrared-conformal gauge theories behave differently, depending on whether the anomalous dimension of the chiral condensate be smaller or larger than 1.Comment: 28 pages, 1 PDF figur

Conformal vs confining scenario in SU(2) with adjoint fermions

The masses of the lowest-lying states in the meson and in the gluonic sector of an SU(2) gauge theory with two Dirac flavors in the adjoint representation are measured on the lattice at a fixed value of the lattice coupling $\beta = 4/g_0^2 = 2.25$ for values of the bare fermion mass $m_0$ that span a range between the quenched regime and the massless limit, and for various lattice volumes. Even for light constituent fermions the lightest glueballs are found to be lighter than the lightest mesons. Moreover, the string tension between two static fundamental sources strongly depends on the mass of the dynamical fermions and becomes of the order of the inverse squared lattice linear size before the chiral limit is reached. The implications of these findings for the phase of the theory in the massless limit are discussed and a strategy for discriminating between the (near--)conformal and the confining scenario is outlined.Comment: 5 pages, 4 figures using RevTeX4, Typos corrected, references added. Versions to appear on PR

Degeneracy Between the Regge Slope of Mesons and Baryons from Supersymmetry

We consider the degeneracy between the Regge slope of mesons and baryons in QCD. We argue that within the "orientifold large-N approximation" asymptotically massive mesons and baryons become supersymmetric partners and hence degenerate. To this end, we generalize QCD by a SU(N) theory with a quark in the two-index antisymmetric representation. We show that in this framework the meson is represented by an oriented bosonic QCD-string and the baryon is represented by an un-oriented fermionic QCD-string. At large-N, due to an equivalence with super Yang-Mills, the tensions of the bosonic and the fermionic strings coincide. Our description of mesons and baryons as oriented and un-oriented bosonic and fermionic QCD-strings is in full agreement with the spectra of open strings in the dual type 0' string theory.Comment: v2: extended version. Appendices and references adde

Large volumes and spectroscopy of walking theories

A detailed investigation of finite-size effects is performed for SU(2) gauge theory with two fermions in the adjoint representation, which previous lattice studies have shown to be inside the conformal window. The system is investigated with different spatial and temporal boundary conditions on lattices of various spatial and temporal extensions, for two values of the bare fermion mass representing a heavy and light fermion regime. Our study shows that the infinite-volume limit of masses and decay constants in the mesonic sector is reached only when the mass of the pseudoscalar particle MPS and the spatial lattice size L satisfy the relation LMPS≥15. This bound, which is at least a factor of three higher than what is observed in QCD, is a likely consequence of the different spectral signatures of the two theories, with the scalar isosinglet (0++ glueball) being the lightest particle in our model. In addition to stressing the importance of simulating large lattice sizes, our analysis emphasizes the need to understand quantitatively the full spectrum of the theory rather than just the spectrum in the mesonic isotriplet sector. While for the lightest fermion measuring masses from gluonic operators proves to be still challenging, reliable results for glueball states are obtained at the largest fermion mass and, in the mesonic sector, for both fermion masses. As a byproduct of our investigation, we perform a finite-size scaling of the pseudoscalar mass and decay constant. The data presented in this work support the conformal behavior of this theory with an anomalous dimension γ*≃0.37

Animal models of compulsive eating behavior

In industrialized nations, overeating is a significant problem leading to overweight, obesity, and a host of related disorders; the increase in these disorders has prompted a significant amount of research aimed at understanding their etiology. Eating disorders are multifactorial conditions involving genetic, metabolic, environmental, and behavioral factors. Considering that compulsive eating in the face of adverse consequences characterizes some eating disorders, similar to the way in which compulsive drug intake characterizes drug-addiction, it might be considered an addiction in its own right. Moreover, numerous review articles have recently drawn a connection between the neural circuits activated in the seeking/intake of palatable food and drugs of abuse. Based on this observation, “food addiction” has emerged as an area of intense scientific research and accumulating evidence suggests it is possible to model some aspects of food addiction in animals. The development of well-characterized animal models would advance our understanding of the etiologic neural factors involved in eating disorders, such as compulsive overeating, and it would permit to propose targeted pharmacological therapies. However, to date, little evidence has been reported of continued food seeking and intake despite its harmful consequences in rats and mice

TRANSCRIPTOMIC ANALYSIS OF WHOLE PISTILS AND OVULE CELLS TO IDENTIFY GENES RELATED TO APOSPORY IN HYPERICUM PERFORATUM L.

St. John\u2019s wort (Hypericum perforatum L.) is a medicinal plant that produces important metabolites with antidepressant and anticancer activities. Beside the pharmaceutical interest, recently gained information has shown that H. perforatum is also an attractive model system for the study of aposporous apomixis, that is a reproductive strategy, which, unlike sexual reproduction, permits the inheritance of the maternal genome over generations without genetic recombination events. This asexual mode of seed formation is believed to be a trait with enormous economic and social potential in agriculture. Its innovative use in this area relies upon the idea that indefinitely fixing highly complex genotypes, including hybrid cultivars, through apomixis would have tremendous advantages in plant breeding, biomass and seed production. During the last decades, the understanding of the molecular basis of apomixis in this species has been complicated by the lack of biological data, e.g. genomic or even transcriptomic sequences. The aim of our research project was the sequencing, annotation and comparative investigation of the H. perforatum flower transcriptome, as critical steps toward a better understanding of the genetic control of aposporic and sexual reproduction in the facultative apomict H. perforatum. To this end, next generation sequencing technologies have been used to sequence the flower transcriptomes of obligate sexual and unrelated apomictic H. perforatum genotypes. This approach has enabled the assembly and annotation of large cDNA repositories and their exploitation to design a custom array to be used in flower expression studies. Global gene expression analysis of H. perforatum was initially performed on ovaries collected from sexual and aposporic plant accessions for the purpose of identifying genes and processes potentially associated with apomixis in this model species. Overall, across two selected developmental stages, 224 and 973 unigenes were found to be significantly upand down-regulated. Ontological annotation of differentially expressed genes indicated that terms related to cell cycle, single-organism cellular process DNA (cytosine-5-)-methyltransferase activity, among others, were significantly enriched. In a following step, a laser-capture microdissection approach was adopted in combination the RNA-seq technology with the aim of identifying genes differentially expressed in the ovule cell types primarily involved in the differentiation of the megaspore mother cells and aposporous initials. On the whole, our data suggest that phenotypic expression of apospory is concomitant with the modulation of key genes involved in the sexual reproductive pathway and the responsive to hormonal stimuli. Annotation of all identified flower transcripts as well as their qualitative and quantitative expression data will be presented and critically discussed as they prove a far better understanding of molecular bases of pistil development, embyo sac and egg cell formation in sexual and apomictic H. perforatum

Improved Lattice Spectroscopy of Minimal Walking Technicolor

We present a numerical study of spectroscopic observables in the SU(2) gauge theory with two adjoint fermions using improved source and sink operators. We compare in detail our improved results with previous determinations of masses that used point sources and sinks and we investigate possible systematic effects in both cases. Such comparison enables us to clearly assess the impact of a short temporal extent on the physical picture, and to investigate some effects due to the finite spatial box. While confirming the IR-conformal behaviour of the theory, our investigation shows that in order to make firm quantitative predictions, a better handle on finite size effects is needed.Comment: 33 pages, 30 figures, 18 table

Domain Walls and Metastable Vacua in Hot Orientifold Field Theories

We consider "Orientifold field theories", namely SU(N) gauge theories with Dirac fermions in the two-index representation at high temperature. When N is even these theories exhibit a spontaneously broken Z2 centre symmetry. We study aspects of the domain wall that interpolates between the two vacua of the theory. In particular we calculate its tension to two-loop order. We compare its tension to the corresponding domain wall in a SU(N) gauge theory with adjoint fermions and find an agreement at large-N, as expected from planar equivalence between the two theories. Moreover, we provide a non-perturbative proof for the coincidence of the tensions at large-N. We also discuss the vacuum structure of the theory when the fermion is given a large mass and argue that there exist N-2 metastable vacua. We calculate the lifetime of those vacua in the thin wall approximation.Comment: 29 pages, 4 figures. v2: minor changes in the introduction section. to appear in JHE

Gd-EOB-DTP-enhanced MRC in the preoperative percutaneous management of intra and extrahepatic biliary leakages: Does it matter?

Postoperative bile leakage is a common complication of abdominal surgical procedures and a precise localization of is important to choose the best management. Many techniques are available to correctly identify bile leaks, including ultrasound (US), computed tomography (CT) or magnetic resonance imaging (MRI), being the latter the best to clearly depict "active" bile leakages. This paper presents the state of the art algorithm in the detection of biliary leakages in order to plan a percutaneous biliary drainage focusing on widely available and safe contrast agent, the Gb-EOB-DPA. We consider its pharmacokinetic properties and impact in biliary imaging explain current debates to optimize image quality. We report common sites of leakage after surgery with special considerations in cirrhotic liver to show what interventional radiologists should look to easily detect bile leaks