The O(N) model on a squashed S^3 and the Klebanov-Polyakov correspondence

We solve the O(N) vector model at large N on a squashed three-sphere with a conformal mass term. Using the Klebanov-Polyakov version of the AdS_4/CFT_3 correspondence we match various aspects of the strongly coupled theory with the physics of the bulk AdS Taub-NUT and AdS Taub-Bolt geometries. Remarkably, we find that the field theory reproduces the behaviour of the bulk free energy as a function of the squashing parameter. The O(N) model is realised in a symmetric phase for all finite values of the coupling and squashing parameter, including when the boundary scalar curvature is negative.Comment: 1+27 pages. 6 figures. LaTeX. References adde

Microwave irradiation synthesis to obtain La0.7-xPrxCa0.3MnO3 perovskites : electrical and electrochemical performance

Atzin Ferrel is grateful for her grants from CONACYT and SIP- IPN. The authors also appreciate the financial support provided by the Consejo Nacional de Ciencia y Tecnología (CONACYT), México, Comisión de Operación y Fomento de Actividades Académicas del IPN (COFAA), México and Secretaría de Investigación y Posgrado (SIP) of the Instituto Politécnico Nacional (IPN) México through the CB2015–252181, 20201278, 20201279, 20201280, 20202443 and 20200909 projects as well as the SNI-CONACyT.La0.7-xPrxCa0.3MnO3 (LPCM) perovskites previously synthesized by the microwave-assisted method at 4 min and with different stoichiometry (x = 0.35, 0.52 and 0.63) were evaluated through thermogravimetric analysis (TGA), electrical conductivity, thermal expansion coefficient (TEC), scanning electron microscopy (SEM), Brunauer- Emmet- Teller (BET) analysis and electrochemical impedance spectroscopy (EIS) using yttria stabilized zirconia (YSZ) as an electrolyte. The results are discussed in terms of the potential as cathode material to be applied in solid oxide fuel cells (SOFCs) applications at temperatures from 600 to 800 °C. Results derived from TGA showed that Pr promotes the uncoupling oxygen and oxygen vacancies favoring the fuel combusting. Also, TEC analysis revealed adequate stability between the YSZ electrolyte and the La0.7-xPrxCa0.3MnO3 to avoid cracking or failing, especially with high amount of Pr. The transition in morphology from irregular to regular shapes improves the BET and Barret- Joyner- Halenda (BJH) surfaces and promotes the triple phase boundary (TPB) connectivity. The electrical conductivity correlated to the availability in oxygen vacancies showed maximum conductivities in the order of 10−2 S cm−1. Activation energy (Ea) was found to be reduced with a minimum quantity of Pr (0.071 eV). EIS results indicate that the oxygen vacancies in the LPCM/YSZ system were better promoted with the highest amount of Pr = 0.63 (η = 0.9 V, 800 °C and 0.06 V of amplitude) in comparison with the minimum, Pr = 0.35 (η = 1.2 V, 800 °C and 0.06 V of amplitude).PostprintPeer reviewe

Physicochemical and melissopalynological profiles of Citrus limon honey from Tucumán-Argentina. Hesperidin as a suitable marker of floral origin

Geographical Indications (GI) are tools used to add value, protect and recognize the differentiated quality of a product as a consequence of environmental and territorial influence. The objective of this work was to determine physicochemical, melissopalynological and sugar profiles plus chemical markers of Citrus limon monofloral honey produced in Tucumán-Argentina, to the development of the GI “Lemon blossom honey from Tucumán”. Samples harvested between August and October 2016, 2017 and 2018 were analyzed. It was established that in addition to Citrus limon, the most frequent pollen species was Salix type. This honey is very light in color (≤ 30 mm Pfund), slightly acidic (≤ 20 meq.kg-1), with moisture values from 15 to 19 g/100g, low diastatic activity (≤ 27 Gothe units), HMF (≤ 3.0 mg.kg-1) and electrical conductivity (≤ 0.32 mS.cm-1). Color inversely correlates with the amount of Citrus limon pollen. The sugar profile showed a higher fructose content than glucose, sucrose and maltose, and intermediate tendency towards crystallization. Hesperidin was easily detected and quantified in all samples. The content of methyl anthranilate was much lower than the international reference for citrus honeys and also, was not detected in some samples. Hence, should be a complementary indicator and hesperidin could be used instead as a chemical marker of genuineness.Las Indicaciones Geográficas (IG) son herramientas utilizadas para agregar valor y para proteger y reconocer la calidad diferencial de un producto como consecuencia de la influencia ambiental y territorial. El objetivo de este trabajo consistió en determinar los perfiles físicoquímicos, melisopalinológicos y de azúcares, además de marcadores químicos de mieles monoflorales de Citrus limon producidas en Tucumán-Argentina, para el desarrollo de la IG “Miel de azahar de limón de Tucumán”. Se analizaron muestras cosechadas entre agosto y octubre de 2016, 2017 y 2018. Se estableció que además de Citrus limon, la especie de polen más frecuente fue la del tipo Salix. Esta miel es de color muy claro (≤ 30 mm Pfund), ligeramente ácida (≤ 20 meq.kg-1), con valores de humedad de 15 a 19 g/100 g, baja actividad diastásica (≤ 27 unidades Gothe), HMF (≤ 3,0 mg.kg-1) y conductividad eléctrica (≤ 0,32 mS.cm-1). El color se correlaciona inversamente con la cantidad de polen de Citrus limon. El perfil de azúcares mostró mayor contenido de fructosa que glucosa, sacarosa y maltosa, y una tendencia intermedia a la cristalización. La hesperidina se detectó y cuantificó fácilmente en todas las muestras. El contenido de metil antranilato fue mucho menor que la referencia internacional para mieles de cítricos y además, no se detectó en algunas muestras. Por lo tanto, debería ser un indicador complementario y la hesperidina podría usarse en su lugar como un marcador químico de autenticidad.EEA FamailláFil: Maldonado, Luis Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; ArgentinaFil: Marcinkevicius, Karenina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Marcinkevicius, Karenina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; ArgentinaFil: Salomon, Virginia María. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; ArgentinaFil: Sanchez, A.C. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas; ArgentinaFil: Sanchez, A.C. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ecorregiones Andinas; Argentina.Fil: Alvarez, Alejandro Raul. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; ArgentinaFil: Lupo, Liliana Concepción. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas; ArgentinaFil: Lupo, Liliana Concepción. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ecorregiones Andinas; Argentina.Fil: Bedascarrasbure, Enrique Luciano. Instituto Nacional de Tecnología Agropecuaria (INTA). Centro de Investigación de Agroindustria. Programa Nacional Apícola (PROAPI); Argentin

Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV

Quasi-elastic scattering of 6He at E_lab=27 MeV from 197Au has been measured in the angular range of 6-72 degrees in the laboratory system employing LEDA and LAMP detection systems. These data, along with previously analysed data of 6He + 208Pb at the same energy, are analyzed using Optical Model calculations. The role of Coulomb dipole polarizability has been investigated. Large imaginary diffuseness parameters are required to fit the data. This result is an evidence for long range absorption mechanisms in 6He induced reactions.Comment: 10 pages, 10 figures, minor corrections. To appear in Nucl. Phys.

Field Theoretical Quantum Effects on the Kerr Geometry

We study quantum aspects of the Einstein gravity with one time-like and one space-like Killing vector commuting with each other. The theory is formulated as a \coset nonlinear $\sigma$-model coupled to gravity. The quantum analysis of the nonlinear $\sigma$-model part, which includes all the dynamical degrees of freedom, can be carried out in a parallel way to ordinary nonlinear $\sigma$-models in spite of the existence of an unusual coupling. This means that we can investigate consistently the quantum properties of the Einstein gravity, though we are limited to the fluctuations depending only on two coordinates. We find the forms of the beta functions to all orders up to numerical coefficients. Finally we consider the quantum effects of the renormalization on the Kerr black hole as an example. It turns out that the asymptotically flat region remains intact and stable, while, in a certain approximation, it is shown that the inner geometry changes considerably however small the quantum effects may be.Comment: 16 pages, LaTeX. The hep-th number added on the cover, and minor typos correcte

Breast cancer PAM50 signature: Correlation and concordance between RNA-Seq and digital multiplexed gene expression technologies in a triple negative breast cancer series

Background: Full RNA-Seq is a fundamental research tool for whole transcriptome analysis. However, it is too costly and time consuming to be used in routine clinical practice. We evaluated the transcript quantification agreement between RNA-Seq and a digital multiplexed gene expression platform, and the subtype call after running the PAM50 assay in a series of breast cancer patients classified as triple negative by IHC/FISH. The goal of this study is to analyze the concordance between both expression platforms overall, and for calling PAM50 triple negative breast cancer intrinsic subtypes in particular. Results: The analyses were performed in paraffin-embedded tissues from 96 patients recruited in a multicenter, prospective, non-randomized neoadjuvant triple negative breast cancer trial (NCT01560663). Pre-treatment core biopsies were obtained following clinical practice guidelines and conserved as FFPE for further RNA extraction. PAM50 was performed on both digital multiplexed gene expression and RNA-Seq platforms. Subtype assignment was based on the nearest centroid classification following this procedure for both platforms and it was concordant on 96% of the cases (N = 96). In four cases, digital multiplexed gene expression analysis and RNA-Seq were discordant. The Spearman correlation to each of the centroids and the risk of recurrence were above 0.89 in both platforms while the agreement on Proliferation Score reached up to 0.97. In addition, 82% of the individual PAM50 genes showed a correlation coefficient > 0.80. Conclusions: In our analysis, the subtype calling in most of the samples was concordant in both platforms and the potential discordances had reduced clinical implications in terms of prognosis. If speed and cost are the main driving forces then the preferred technique is the digital multiplexed platform, while if whole genome patterns and subtype are the driving forces, then RNA-Seq is the preferred method

The inverse problem of determining the filtration function and permeability reduction in flow of water with particles in porous media

The original publication can be found at www.springerlink.comDeep bed filtration of particle suspensions in porous media occurs during water injection into oil reservoirs, drilling fluid invasion of reservoir production zones, fines migration in oil fields, industrial filtering, bacteria, viruses or contaminants transport in groundwater etc. The basic features of the process are particle capture by the porous medium and consequent permeability reduction. Models for deep bed filtration contain two quantities that represent rock and fluid properties: the filtration function, which is the fraction of particles captured per unit particle path length, and formation damage function, which is the ratio between reduced and initial permeabilities. These quantities cannot be measured directly in the laboratory or in the field; therefore, they must be calculated indirectly by solving inverse problems. The practical petroleum and environmental engineering purpose is to predict injectivity loss and particle penetration depth around wells. Reliable prediction requires precise knowledge of these two coefficients. In this work we determine these quantities from pressure drop and effluent concentration histories measured in one-dimensional laboratory experiments. The recovery method consists of optimizing deviation functionals in appropriate subdomains; if necessary, a Tikhonov regularization term is added to the functional. The filtration function is recovered by optimizing a non-linear functional with box constraints; this functional involves the effluent concentration history. The permeability reduction is recovered likewise, taking into account the filtration function already found, and the functional involves the pressure drop history. In both cases, the functionals are derived from least square formulations of the deviation between experimental data and quantities predicted by the model.Alvarez, A. C., Hime, G., Marchesin, D., Bedrikovetski, P

Clostridium difficile sortase recognizes a (S/P)PXTG sequence motif and can accommodate diaminopimelic acid as a substrate for transpeptidation

AbstractCovalent attachment of surface proteins to the cell wall of Gram-positive bacteria requires a sortase-mediated transpeptidation reaction. In almost all Gram-positive bacteria, the housekeeping sortase, sortase A, recognizes the canonical recognition sequence LPXTG (X=any amino acid). The human pathogen Clostridium difficile carries a single putative sortase gene (cd2718) but neither transpeptidation activity nor specificity of CD2718 has been investigated. We produced recombinant CD2718 and examined its transpeptidation activity in vitro using synthetic peptides and MALDI-ToF(-ToF) MS analysis. We demonstrate that CD2718 has sortase activity with specificity for a (S/P)PXTG motif and can accommodate diaminopimelic acid as a substrate for transpeptidation