A dynamical metric and its ground state from the breaking down of the topological invariance of the Euler characteristic

Quantum state wave functionals are constructed in exact form for the graviton-like field theory obtained by breaking down the topological symmetry of the string action related with the Euler characteristic of the world-surface; their continuous and discrete symmetries are discussed. The comparison with the so-called Chern-Simons state, which may be inappropriate as quantum state, allows us to conclude that the found wave functionals will give a plausible approximation to the ground state for the considered field theory

Functionalization of p-activated alcohols by trapping carbocations in pure water under smooth conditions

Acetic acid as catalyst in pure water was found to be an excellent reaction medium for the direct dehydrative functionalization of p-activated alcohols using a wide variety of interesting C-, P-, and S-centered nucleophiles, such as indoles, pyrrole, anilines, 1, 3-dicarbonyl compounds, diphenyl phosphite and pyridine-2-thiol. The smooth reaction conditions, along with high yields, short reaction times, clean reaction crudes, an easy product isolation procedure, plus the reusability of the catalyst and the use of no excess of nucleophiles, make this approach an atom economical, green and appealing method to efficiently trap carbocations in pure water, leading to new Csp3 X bonds (X = Csp2, Csp3, P and S)

Comparative evaluation of impedanciometry combined with chromogenic agars or RNA hybridization and real-time PCR methods for the detection of L. monocytogenes in dry-cured ham

Listeria monocytogenes is an important foodborne pathogen of particular relevance in “Ready To Eat” products. Food producers require rapid methods to detect L. monocytogenes, since the reference method (ISO 11290-1) is laborious, lengthy and costly. The aim of this study was to evaluate three alternative methods to detect L. monocytogenes in dry-cured ham following the ISO 16140-2:2016 standard: (A) impedance measurement followed by plating onto chromogenic agars; (B) impedance measurement followed by RNA hybridization, and (C) real-time PCR. Inclusivity and exclusivity were evaluated. The limits of detection 50 (LOD50) and the relative limits of detection (RLOD) were obtained by analysing dry-cured ham samples inoculated with L. monocytogenes at three different levels of contamination. The sensitivity study of alternative methods, as well as the relative specificity (SP), sensitivity (SE), and Kappa Cohen''s index were calculated analysing 93 samples of sliced dry-cured ham. The inclusivity and exclusivity tests of three methods showed no interference in pathogen detection. LOD50 were very low for the three methods evaluated (<1 cfu/25 g dry-cured ham). The RLOD values of the three alternative methods were below the acceptability limit established by ISO 16140. For methods A and C, good results were obtained in the sensitivity study, as well as in the SP and SE. However, method B showed poorer results in the sensitivity study, along with lower results for SP (99.7%) and SE (79.6%), due to the occurrence of false positives and negatives in samples with presence of other Listeria spp. Methods A and C were considered to be a thoroughly appropriate control tool for use in the meat industry to improve the detection of L. monocytogenes

Spherically symmetric dissipative anisotropic fluids: A general study

The full set of equations governing the evolution of self--gravitating spherically symmetric dissipative fluids with anisotropic stresses is deployed and used to carry out a general study on the behaviour of such systems, in the context of general relativity. Emphasis is given to the link between the Weyl tensor, the shear tensor, the anisotropy of the pressure and the density inhomogeneity. In particular we provide the general, necessary and sufficient, condition for the vanishing of the spatial gradients of energy density, which in turn suggests a possible definition of a gravitational arrow of time. Some solutions are also exhibited to illustrate the discussion.Comment: 28 pages Latex. To appear in Phys.Rev.

Biochemical and molecular characterization of olive β-glucosidase in seven olive varieties during the ripening process: the role of β-glucosidase in determining the phenolic content of virgin olive oil.

Virgin olive oil (VOO) is one of the essential components of the Mediterranean diet, which includes a series of cultural habits, especially alimentary, shared to a greater or lesser extent, by all countries lapped by Mediterranean Sea. VOO is enriched with bioactive compounds which are related to its unique organoleptic characteristics, and also to its antioxidant properties, which have been associated to with the reduction of risk to suffer cardiovascular diseases and to a protective effect against cancer. The most important bioactive components in VOO are phenolics compounds [2].The phenolic composition of VOO is closely related to the content of phenolic glycosides initially present in the olive tissue. In parallel, some studies indicate that there is a positive correlation between the activity levels of β-glucosidase in the olive fruit and the final content of phenolic compounds in VOO. This enzyme plays a key role hydrolyzing phenolic profile of VOO. In consequence, its biochemical and molecular characterization is of great interest from a biotechnological point of view [1, 2].In this study, seven olive varieties (Abou-Kanani, Dokkar, Klon-14, Menya, Picual, Piñonera y Shengeh) with different phenolic contents have been selected in the World Olive Germplasm Bank. The phenolic profiles of fruits harvested at different ripening stages and their oils have been analyzed by HPLC and at the same time β-glucosidase activity has been measured in olive fruits at different ripening stages. The methods for β-glucosidase extraction and activity assessment have been optimized. Spectrophotometric activity assays have been carried out with the synthetic substrate p-nitrophenyl galactoside (p-NPG) using a calculated molar extinction coefficient (ε=552,8 M-1cm-1) for the p-nitrophenyl liberated in the reaction medium. The results obtained show that olive varieties with the highest content of phenolic glycosides in the fruit such as Piñonera, Dokkar or Menya, also have the largest β-glucosidase activity levels, which usually decrease ripening process. These results will be completed with the pertinent studies of gene expression [3]