The recent star formation history of the Hipparcos solar neighbourhood

We use data from the Hipparcos catalogue to construct colour-magnitude diagrams for the solar neighbourhood, which are then treated using advanced Bayesian analysis techniques to derive the star formation history, $SFR(t)$, of this region over the last 3 Gyr. The method we use allows the recovery of the underlying $SFR(t)$ without the need of assuming any {\it a priori} structure or condition on $SFR(t)$, and hence yields a highly objective result. The remarkable accuracy of the data permits the reconstruction of the local $SFR(t)$ with an unprecedented time resolution of $\approx 50$ Myr. A $SFR(t)$ having an oscillatory component of period $\approx 0.5$ Gyr is found, superimposed on a small level of constant star formation activity. Problems arising from the non-uniform selection function of the Hipparcos satellite are discussed and treated. Detailed statistical tests are then performed on the results, which confirm the inferred $SFR(t)$ to be compatible with the observed distribution of stars.Comment: 9 pages including figures, MNRAS in pres

An inverse method to interpret colour-magnitude diagrams

An inverse method is developed to determine the star formation history, the age-metallicity relation, and the IMF slope from a colour-magnitude diagram. The method is applied to the Hipparcos HR diagram. We found that the thin disk of our Galaxy shows a peak of stellar formation 1.6 Gyr ago. The stars close to the Sun have a solar metallicity and a mean IMF index equal to 3.2. However, the model and the evolutionary tracks do not correctly reproduce the horizontal giant branch.Comment: 14 pages, 11 figures. To be published in Astronomy & Astrophysic

Synthesis and Electrical Characterization of PLZT Piezoelectric-Ceramic

This research describes the synthesis of an outstanding ceramic-composite piezoelectric CCP (lead-lanthanum-zirconate-titanate, PLZT) by means of powders technique procedures. Full dense CCP compacts were obtained with a platinum wire implanted in the center of the piezoelectric, which were used to investigate the microstructural and opto-thermal properties. The microstructural details of this ceramic were investigated by optical microscopy; whereas the opto-thermal characterization was performed by measuring the electrical signal in a bidimensional setup under four different temperatures: 20°C, 35°C, 50°C and 75°C. A 160mW/cm2 LASER beam was used in order to produce the optical energy which is detected by the CCP. A total of one hundred of measurements were registered. Measurements showed that, in the explored thermal range, the CCP signal magnitude increased from 87.2 to 147.2 pA. About the microstructural analysis, the microstructure obtained show different phases as characteristic of the processing method, including porosity. The peculiar optical and thermal properties observed in the piezoelectric ceramic are promising for possible applications in temperature-controlled optical devices that require electrical outputs

Perturbations to the IGF1 growth pathway and adult energy homeostasis following disruption of mouse chromosome 12 imprinting

AIM: Disruption to insulin-like growth factor (IGF) signalling pathways during early life causes growth retardation and defects of developing metabolic organs that can alter set points of energy homeostasis for a lifetime. Inheritance of two maternal copies of human chromosome 14q32.2 (Temple syndrome) causes severe foetal growth retardation and post-natal failure to thrive. Disruption of imprinted gene dosage in the orthologous region on mouse chromosome 12 also affects growth. Here, we investigated whether altering chromosome 12-imprinted gene dosage can affect IGF signalling. METHODS: We investigated mice with a transgene insertion at the imprinted domain of chromosome 12. This lesion causes misexpression of neighbouring genes such that the expression of non-coding RNAs is elevated, and levels of delta-like homologue 1 (Dlk1), retrotransposon-like 1 (Rtl1) and deiodinase 3 (Dio3) transcripts are reduced. RESULTS: We observed three key phenotypes in these mice: (i) embryonic growth retardation associated with altered expression of IGF1 binding proteins, (ii) peri-natal failure to thrive accompanied by hypothyroidism and low serum IGF1. Unexpectedly this phenotype was growth hormone independent. (iii) Adult animals had reduced glucose tolerance as a result of endocrine pancreatic insufficiency. CONCLUSIONS: We propose that all of these phenotypes are attributable to impaired IGF action and show for the first time that the chromosome 12 cluster in the mouse is an imprinted locus that modulates the IGF signalling pathway. We propose that growth retardation observed in human Temple syndrome might have a similar cause

Influencia del Marketing del servicio en el proceso de decisión de compra en el Supermercado La Colonia-Matagalpa, II Semestre del año 2020

El presente documento abordó la Influencia del Marketing del servicio en el proceso de decisión de compra en el supermercado la colonia, departamento de Matagalpa en el segundo semestre del año 2020. Con el fin de Identificar la aplicación de los elementos de la flor Servicio con los que el cliente entra en contacto mediante el servicio, también se determinó el proceso de decisión de compra que se ejecuta en el supermercado y por último se valoró la influencia del marketing del servicio en la decisión de compra. La temática de estudio fue de gran importancia, ya que, esta busca el manejo de la satisfacción a través de las percepciones positivas del servicio en general, los instrumentos utilizados para esta son métodos empíricos y teóricos tales como: Diferencial Semántico, Entrevista, Guía de Observación y Mapa perceptual a los clientes sobre el Marketing de servicio, los elementos de la flor del servicio y el proceso de decisión de compra, esto con el objetivo de proporcionar diferentes opiniones o percepciones de los clientes que fueron de gran ayuda para la investigación. Los resultados obtenidos en esta investigación revelan que el supermercado La Colonia posee una buena imagen mayor a la media de imagen positiva, de la misma manera que el en todo el proceso de decisión de compra el supermercado está presente excepto en la etapa post compra y de la misma manera que él se ha ejecutado excelente el marketing de servicio debido a la variedad de estrategias. Palabras Clave: Marketing de Servicio, decisión de compra, atención al cliente, Cliente, Supermercado, Consumidore

Alumina-Based Composites Reinforced With Silver Particles

Al2O3/Ag composite ceramics were fabricated by the use of mechanical milling and pressureless sintering. Al2O3 + 10 wt.% Ag were mixed and milled during 12 h at 300 rpm in a horizontal mill, then with the powder mixture it was conformed cylindrical samples by uniaxial pressing using 300 MPa. The pressed samples were sintered during 1 h in an electrical furnace at 1300, 1400 and 1500°C respectively. Sinter was performed using an argon atmosphere inside the furnace in order to inhibit silver oxidation. XRD results established that silver retains its crystalline structure. On the other hand, density of samples is better with increments in temperature. However, the final relative density is small and about of 91%. Scanning electron microscopy observations show alumina’s microstructure with very fine and homogeneous distributions of silver particles. Increments in sintering temperature are reflected as enhancements of the density and consequently of the fracture toughness of the Al2O3/Ag composite ceramics

PRODUCCIÓN ORGÁNICA DE LECHE DE OVEJA

Los sistemas de producción orgánicos se basan en procesos naturales, aprovechamiento de recursos locales y disminución en la degradación del suelo. La efectividad de la producción de leche de los sistemas orgánicos vs los sistemas de producción convenciona les es un tema abierto a debate. Son diversos los estudios en los cuales se observa un efecto positivo de los sistemas orgánicos de producción de leche de oveja en relación al bienestar y salud animal, calidad de los productos e impacto ambiental. No obsta nte, algunos autores citan rendimientos lácteos inferiores, así como mayor susceptibilidad a condiciones medioambientales comparados con los obtenidos en sistemas convencionales. Los menores rendimientos en los sistemas orgánicos de producción de leche de oveja, están relacionados con el limitado aporte nutricional, el bajo potencial genético, así como las cambiantes condiciones medioambientales. Estos sistemas ovinos son principalmente un método de producción para un mercado específico que ofrece productos con calidad Premium y elevados estándares de calidad en sus procesos de producción. Por lo que una empresa ovina orgánica de producción de leche debe ser considerada viable en la medida que presente un balance positivo a nivel de sostenibilidad global, es decir, que sea socialmente benéfica , económicamente viable y medioambientalmente responsable

Programmed Cell Death-Related Proteases in Plants

From an ancient Greek term related to the “leavening of bread” (en, in; zyme, leaven), an enzyme can be defined as a substance showing the properties of a catalyst that is produced as a result of cellular activity. Every proteinaceous enzyme that performs hydrolysis of peptide bonds is appropriately termed “protease” (peptidase). All of them share aspects of catalytic strategy, but with some variation. As a result, the proteases are grouped into six different catalytic families: serine, threonine, cysteine, aspartic, glutamic and metallopeptidases (http://merops.sanger.ac.uk/). The larger families (cysteine, serine, aspartic and metallopeptidases) have a wide range of distribution on living organism groups, and are also present in the “controversial” viruses. As a well‐represented family, the cysteine proteases play important roles in events such as signalling pathways, programmed cell death (PCD), nutrient mobilization, protein maturing, hormone synthesis and degradation. In the past two decades, an increased interest was driven to the study of the programmed cell death (PCD), mainly after the discovery of caspase‐related proteins and caspase‐like activities in organisms not metazoan. Caspases are cysteine proteases that cleave their substrate after aspartate residues and are part of signalling cascades of the apoptotic PCD process (also in inflammatory process), unique of metazoan. The caspase‐related proteins are named paracaspases and metacaspases. Paracaspases are found on metazoan and Dictyostelium, whereas the metacaspases are present on plants, fungi and groups of protozoan. On plants, PCD has features that are distinct from that of animals and is an important pathway on developmental events, defensive and stress response (biotic and abiotic). All these events have their own particularities, but the participation of proteases seems to be universal with those responsible for caspase‐like activities and metacaspases having an increasing number of reports that put them as important for plant PCD. In this chapter, we tackle important aspects of the proteases, in special that involved in plant PDC, as well as their specific regulators. Aspects of function, catalytic mechanisms and interaction with ligands will be on focus

Correlation between Simulations and Experimentation: Simple Approach for Technological Teaching / Correlação Entre Simulação e Experimentação: Abordagem Simples Para o Ensino Tecnológico

Technological education requires high-cost equipment that, in most cases, does not favor a good understanding of the phenomenon occurring during its use. A possible solution is simulation; however, without the corresponding experimentation, it does not contribute for elucidation of real problems when using such equipment. A critical problem for Chemical Engineering and Chemistry is heating of fluids in small dimensions, as occurs in chromatographic columns and distillation tower. Therefore, this work aims the manufacturing of a prototype and corresponding simulation, for such learning process. The obtained product was manufactured with low-cost materials and conventional machining instruments. Simulation used FEMLAB® program and was carried out in 1D. The device is miniaturized and suitable for classroom demonstrations. Moreover, it allows an easy understanding between temperature programming and the corresponding chromatographic peak profile, essential parameter in performance measurement. Thus, simple ways of manufacturing were developed with low costs but accurate equipment.