Intra-specific variability and unusual organization of the repetitive units in a satellite DNA from Rana dalmatina: molecular evidence of a new mechanism of DNA repair acting on satellite DNA.

We have characterized the S1 satellite from eight European populations of Rana dalmatina by Southern blot, cloning and a new method that determines the sequence variability of repetitive units in the genome. This report completes our previous studies on this satellite DNA family, thus providing the first characterization of the overall variability of the structure and genomic organization of a satellite DNA within a species and among related species. The S1 satellite from R. dalmatina has a pericentromeric location on ten chromosome pairs and presents two homologous repeats S1a (494 bp) and S1b (332 bp), mostly organized as composite S1a-S1b repetitive units. In other brown frog species, both repeats have different sequences and locations, and are usually organized as separate arrays, although composite S1a-S1b repeats represent a minor, widely variable component in Rana italica. The average genomic sequences indicate that the species contains an enormous number of variants of each repeat derived from a unique, species-specific common sequence. The repeat variability is restricted to specific base changes in specific sequence positions in all population samples. Our data show that the structure and evolution of S1 satellite family is not due to crossing-over and gene conversion, but to a mechanism that maintains the ability of the satellite DNA to assemble in constitutive heterochromatin by replacing altered satellite segments with new arrays generated by rolling circle amplification. The mode of action of this repair process not only directly explains the intra- and inter-specific variability of the structure and organization of the S1 satellite repeats from European brown frogs, but also accounts for all general features of satellite DNA in eukaryotes, including its discontinuous evolution. This repair mechanism can maintain the satellite structure in a species indefinitely, but also promote a rapid generation of new variants or types of satellite DNA when environmental conditions favor the formation of new species

Flavored tetraquark spectroscopy

The recent confirmation of the charged charmonium like resonance Z(4430) by the LHCb experiment strongly suggests the existence of QCD multi quark bound states. Some preliminary results about hypothetical flavored tetraquark mesons are reported. Such states are particularly amenable to Lattice QCD studies as their interpolating operators do not overlap with those of ordinary hidden-charm mesons

Adult Education to Become Citizen. An Experience from Southern Europe

In this paper, we present a reflection on experiences with adult education and participation. We consider citizenship as something connected to social justice and to social inclusion

Comparison of two bias reduction techniques for the Rasch model

This study examines the effect of two different techniques of bias reduction in the case of the fixed persons-fixed items formulation of the Rasch model. A first approach can be considered “corrective”, because it consists simply in correcting ex-post the joint maximum likelihood estimates by a factor (m-1)/m, were m represents the number of items and/or persons. A second approach, which is an application of a quite general formula for reducing the maximum likelihood estimation bias, can be considered “preventive”, because it arises from a modification of the score function. A comparative study of these two techniques was done using simulated data

Non-autonomous overdetermined problems for the normalized p -Laplacian

We present existence and nonexistence results on the solution of an overdetermined problem for the normalized p-Laplacian in a bounded open set, with p ranging from 1 to infinity. More precisely we consider a non-constant Neumann condition at the boundary. The definitions and statements needed to understand the main results are recalled in detail

TOXICITY OF PREDNISOLONE, DEXAMETHASONE AND THEIR PHOTOCHEMICAL DERIVATIVES ON AQUATIC ORGANISMS

Light exposure of aqueous suspensions of prednisolone and dexamethasone causes their partial phototransformation. The photoproducts, isolated by chromatographic techniques, have been identified by spectroscopic means. Prednisolone, dexamethasone and their photoproducts have been tested to evaluate their acute and chronic toxic effects on some freshwater chain organisms. The rotifer Brachionus calyciflorus and the crustaceans Thamnocephalus platyurus and Daphnia magna were chosen to perform acute toxicity tests, while the alga Pseudokircheneriella subcapitata (formerly known as Selenastrum capricornutum) and the crustacean Ceriodaphnia dubia to perform chronic tests. The photochemical derivatives are more toxic than the parent compounds. Generally low acute toxicity was found. Chronic exposure to this class of pharmaceuticals caused inhibition of growth population on the freshwater crustacean C. dubia while the alga P. subcapitata seems to be less affected by the presence of these drugs

Propuesta de implementación de mantenimiento productivo total (TPM) en el área de extracción de jugo trapiche para medir el impacto de la productividad de la agroindustria Pomalca SAA

El presente trabajo tiene como propósito proponer la implementación de mantenimiento productivo total (TPM) en el área de extracción de jugo trapiche para medir el impacto de la productividad de la agroindustria Pomalca SAA, en el presente estudio se enfoca en la situación actual de la compañía mediante un análisis para determinar cómo está realizando y de que forma el mantenimiento puede causar la disminución en el proceso de extracción de jugo de caña, dando origen a pérdidas económicas en la productividad. Por tal motivo se plantearon objetivos como realizar un diagnóstico basado en la identificación de las pérdidas ocasionadas en el área de extracción de jugo de caña, calcular la efectividad global de los equipos en el área de extracción de jugo de caña, proponer la implementación del mantenimiento total productivo apoyado con el mantenimiento autónomo y realizar un análisis costo beneficio de la propuesta para disminuir las pérdidas de la productividad. La propuesta estará basada en el análisis previo mediante la eficiencia global de los equipos y como mejorarla para poder incrementar las paradas con la mejora en el mantenimiento. Una vez identificado la OEE de los equipos, se determinó que un correcto mantenimiento, para una molienda de 252 138,24 t de caña se obtuvo 28 540,65 t de azúcar, con la mejora se va a llegar a 29 093,4 t de azúcar, recuperando 552,72 t de azúcar