325 research outputs found

    On a Holographic Model for Confinement/Deconfinement

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    We study the thermodynamics of the hard wall model, which consists in the introduction of an infrared cut-off in asymptotically AdS spaces. This is a toy model for confining backgrounds in the context of the gauge/gravity correspondence. We use holographic renormalization and reproduce the existence of a Hawking Page phase transition recently discussed by Herzog. We also show that the entropy jumps from N0N^0 to N2N^2, which reinforces the interpretation of this transition as the gravity dual of confinement/deconfinement. We also show that similar results hold for the phenomenologically motivated soft wall model, underlining the potential universality of our analysis.Comment: 14 pages. V2: We included a new section discussing the soft wall model and new references. V3: We clarified some points and updated the references. Results unchanged. Version published in PR

    Deep Inelastic Scattering in Conformal QCD

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    We consider the Regge limit of a CFT correlation function of two vector and two scalar operators, as appropriate to study small-x deep inelastic scattering in N=4 SYM or in QCD assuming approximate conformal symmetry. After clarifying the nature of the Regge limit for a CFT correlator, we use its conformal partial wave expansion to obtain an impact parameter representation encoding the exchange of a spin j Reggeon for any value of the coupling constant. The CFT impact parameter space is the three-dimensional hyperbolic space H3, which is the impact parameter space for high energy scattering in the dual AdS space. We determine the small-x structure functions associated to the exchange of a Reggeon. We discuss unitarization from the point of view of scattering in AdS and comment on the validity of the eikonal approximation. We then focus on the weak coupling limit of the theory where the amplitude is dominated by the exchange of the BFKL pomeron. Conformal invariance fixes the form of the vector impact factor and its decomposition in transverse spin 0 and spin 2 components. Our formalism reproduces exactly the general results predict by the Regge theory, both for a scalar target and for gamma*-gamma* scattering. We compute current impact factors for the specific examples of N=4 SYM and QCD, obtaining very simple results. In the case of the R-current of N=4 SYM, we show that the transverse spin 2 component vanishes. We conjecture that the impact factors of all chiral primary operators of N=4 SYM only have components with 0 transverse spin.Comment: 44+16 pages, 7 figures. Some correction

    Genomic landscape and immune-related gene expression profiling of epithelial ovarian cancer after neoadjuvant chemotherapy

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    Ovarian cancerCàncer d'ovariCáncer de ovarioPlatinum-based neoadjuvant chemotherapy followed by interval debulking surgery is an accepted treatment for patients with stage III or IV epithelial ovarian cancer who are not suitable for primary debulking surgery. The identification of suitable adjuvant treatments in these patients is an unmet need. Here, we explore potential genomic characteristics (mutational and immune-associated expression profiles) in a series of patients undergoing neoadjuvant chemotherapy. Tumor samples from biopsy and interval debulking surgery were analyzed for mutational landscape and immune profiling, together with detailed immunohistochemistry using different immune cell markers, and correlated with clinicopathological characteristics and potential response to neoadjuvant chemotherapy. No major differences in the mutational landscape were observed in paired biopsy and surgery samples. Genomic loss of heterozygosity was found to be higher in patients with total/near-total tumor response. The immune gene expression profile after neoadjuvant chemotherapy revealed activation of several immune regulation-related pathways in patients with no/minimal or partial response. In parallel, neoadjuvant therapy caused a significant increase of tumor-infiltrating lymphocyte population abundance, primarily due to an augmentation of the CD8+ T cell population. Remarkably, these changes occurred irrespective of potential homologous recombination defects, such as those associated with BRCA1/2 mutations. Our study strengthens the use of loss of heterozygosity as a biomarker of homologous repair deficiency. The changes of immune states during neoadjuvant chemotherapy reveal the dynamic nature of tumor-host immune interactions and suggest the potential use of immune checkpoint inhibitors or their combination with poly-ADP polymerase inhibitors in high stage and grade epithelial ovarian cancer patients undergoing neoadjuvant therapy.This study was funded by GlaxoSmithKline (GSK). I.L. position is funded by Fundación Científica Asociación Española Contra el Cáncer (AECC), Predoctoral AECC 2019 grant number PRDMA19024LODE. L. Morales position is funded by AECC, Postdoctoral AECC 2019 grant number POSTD19036MORA. This study was partially co-funded by European Regional Development Fund (FEDER) grants from Science and Innovation (SAF2015-66015-R and PID2019-110758RB-I00 to J.M.P.) and Instituto de Salud Carlos III (CIBERONC no. CB16/12/00228 to J.M.P.)

    Anti-de Sitter boundary in Poincare coordinates

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    We study the space-time boundary of a Poincare patch of Anti-de Sitter (AdS) space. We map the Poincare AdS boundary to the global coordinate chart and show why this boundary is not equivalent to the global AdS boundary. The Poincare AdS boundary is shown to contain points of the bulk of the entire AdS space. The Euclidean AdS space is also discussed. In this case one can define a semi-global chart that divides the AdS space in the same way as the corresponding Euclidean Poincare chart.Comment: In this revised version we add a discussion of the physical consequences of the choice of a coordinate system for AdS space. We changed figure 1 and added more references. Version to be published in Gen. Relat. Grav

    Pharmacologic concentrations of linezolid modify oxidative phosphorylation function and adipocyte secretome

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    The oxidative phosphorylation system is important for adipocyte differentiation. Therefore, xenobiotics inhibitors of the oxidative phosphorylation system could affect adipocyte differentiation and adipokine secretion. As adipokines impact the overall health status, these xenobiotics may have wide effects on human health. Some of these xenobiotics are widely used therapeutic drugs, such as ribosomal antibiotics. Because of its similarity to the bacterial one, mitochondrial translation system is an off-target for these compounds. To study the influence of the ribosomal antibiotic linezolid on adipokine production, we analyzed its effects on adipocyte secretome. Linezolid, at therapeutic concentrations, modifies the levels of apolipoprotein E and several adipokines and proteins related with the extracellular matrix. This antibiotic also alters the global methylation status of human adipose tissue-derived stem cells and, therefore, its effects are not limited to the exposure period. Besides their consequences on other tissues, xenobiotics acting on the adipocyte oxidative phosphorylation system alter apolipoprotein E and adipokine production, secondarily contributing to their systemic effects

    Holographic zero sound at finite temperature in the Sakai-Sugimoto model

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    In this paper, we study the fate of the holographic zero sound mode at finite temperature and non-zero baryon density in the deconfined phase of the Sakai-Sugimoto model of holographic QCD. We establish the existence of such a mode for a wide range of temperatures and investigate the dispersion relation, quasi-normal modes, and spectral functions of the collective excitations in four different regimes, namely, the collisionless quantum, collisionless thermal, and two distinct hydrodynamic regimes. For sufficiently high temperatures, the zero sound completely disappears, and the low energy physics is dominated by an emergent diffusive mode. We compare our findings to Landau-Fermi liquid theory and to other holographic models.Comment: 1+24 pages, 19 figures, PDFTeX, v2: some comments and references added, v3: some clarifications relating to the different regimes added, matches version accepted for publication in JHEP, v4: corrected typo in eq. (3.18

    Deep inelastic scattering of baryons in a modified soft wall model

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    We calculate the structure functions for unpolarized deep inelastic scattering of baryons using an AdS/QCD soft wall model that considers a dressed mass for the bulk fermionic fields. Considering the regime of large Bjorken parameter x, we compare the results for the proton structure function F2F_2 with experimental results.Comment: We improved the comparison with experimental data and included more references, version to appear in EPJ

    Development, implementation, and evaluation of the Apollo model of pediatric rehabilitation service delivery

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    This article presents the experience of a rehabilitation program that un- dertook the challenge to reorganize its services to address accessibility issues and im- prove service quality. The context in which the reorganization process occurred, along with the relevant literature justifying the need for a new service delivery model, and an historical perspective on the planning; implementation; and evaluation phases of the process are described. In the planning phase, the constitution of the working committee, the data collected, and the information found in the literature are presented. Apollo, the new service delivery model, is then described along with each of its components (e.g., community, group, and individual interventions). Actions and lessons learnt during the implementation of each component are presented. We hope by sharing our experiences that we can help others make informed decisions about service reorganization to im- prove the quality of services provided to children with disabilities, their families, and their communities

    Protein trafficking through the endosomal system prepares intracellular parasites for a home invasion

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    Toxoplasma (toxoplasmosis) and Plasmodium (malaria) use unique secretory organelles for migration, cell invasion, manipulation of host cell functions, and cell egress. In particular, the apical secretory micronemes and rhoptries of apicomplexan parasites are essential for successful host infection. New findings reveal that the contents of these organelles, which are transported through the endoplasmic reticulum (ER) and Golgi, also require the parasite endosome-like system to access their respective organelles. In this review, we discuss recent findings that demonstrate that these parasites reduced their endosomal system and modified classical regulators of this pathway for the biogenesis of apical organelles
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