Genetic variation of wood density components in coastal Douglas- fir and their relationships to growth rhythm

Overall wood density is a complex trait resulting from the interaction of three components: average earlywood density, average latewood density, and latewood proportion. In order to better understand the genetic control of wood density in juvenile Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and to assess the utility of information on its components for improving the efficiency of selection for overall wood density, wood density components were examined in 15-year-old trees of 60 open-pollinated families. Wood density traits were obtained on a ring-by-ring basis by X-ray densitometry of increment cores. In addition to providing information on overall wood density traits over the entire cores, these data made it possible to examine changes in wood density traits with increasing distance from the pith. Relationships between wood density traits and growth phenology, and their implications for tree breeding, were also examined. Overall core density showed strong genetic control (h = 0.59) and a negative genetic correlation with bole volume (rA = -0.52). Wood density components were strongly genetically related with overall core density, but they were also strongly related among themselves and had lower heritability than overall core density. Therefore, information on density components would not be useful for improving the efficiency of selection for overall core density, or for reducing the negative correlated response on volume growth. It is possible, however, to substantially increase volume growth without loss in wood density, or even while slightly increasing wood density, when both traits are included in selection indices. Genetic control of overall core density and its components increased with age (ages 7 to 15). Overall core density and its components at age 15 were also strongly genetically correlated with their respective traits at all younger ages examined. Thus, early selection for overall core density at age 15 would be very effective. Including density components as secondary traits did not enhance the efficiency of early selection for overall core density. Ring density and its components (adjusted by ring size) followed different age trends, but the slopes of the trends did not differ significantly among families. A plateau in the earlywood density trend was observed around age 12 in some trees, and families varied in the proportion of trees having this plateau. This proportion was not correlated with overall core density or with growth traits at age 15. It is hypothesized that the plateau in earlywood density trend might be related to an earlier juvenile-mature transition age. Overall core density and all its components were negatively correlated with dates of cambial growth initiation and latewood transition, and positively correlated with date of cambial growth cessation. Thus, selection for higher wood density would cause a slight extension in the cambial growth period, and an earlier transition to latewood formation. Wood density was not genetically correlated with the date of budburst

Information Technology and Competitive Advantage: The Role of the Ownership Structure

This paper analyses the relationship between information technology use (IT) and competitive advantage. Previous empirical research shows that IT improves competitive advantage when it acts together with some human or managerial resources of an intangible nature. In this work we propose a new complementary resource to IT: democratic ownership structure. We empirically analyse whether ownership structure and IT have a positive, combined impact on competitive advantage. Results show that ownership structure is a key element in explaining competitive advantage differences. Nonetheless, we did not find any IT-ownership structure complementary effect

Síntesis de nanopartículas de TiO2 con alta área superficial para degradación de contaminantes en agua

Síntesis de nanopartículas con baja aglomeración a partir del método sol-gel, con el uso de un surfactante Polivinilpirrolidona PVP.El dióxido de titanio es uno de los materiales más importantes y básicos de nuestra vida diaria, ha emergido como un material con excelente propiedades fotocatalíticas para la purificación del medio ambiente. Sin embargo existen limitaciones debido a la naturaleza de la muestra que impiden que incremente su eficiencia de degradación de colorantes orgánicos. La originalidad de este proyecto consiste en sintetizar dióxido de titanio con alta área superficial. El preparar materiales a escala nanométrica tiene grandes ventajas debido a que para alguna aplicaciones los materiales incrementan sus propiedades enormemente. Sin embargo para el proceso de fotocatálisis existe un fenómeno que disminuye su eficiencia, llamado “aglomeración”. Dicho fenómeno consiste en que las partículas con tamaño nanométrico, se unen mediante fuerzas electrostáticas, reduciendo el área expuesta. En este proyecto se trabajaron con surfactantes orgánicos que tienen la función de evitar que las partículas se aglomeren y con ello aumenten su eficiencia fotocatalítica. Los resultados de microscopía electrónica de barrido de alta resolución muestran que el surfactante tiene el efecto que se deseaba debido a que se muestran partículas menos aglomeradas. Dicha propiedad aumento la eficiencia de degradación del azul de metileno general, el cual presenta deplorables condiciones

ESTUDIOS POR FOTORREFLECTANCIA Y AUGER DE LA REACTIVIDAD DE PELICULAS DE CdTe SOMETIDAS A FLUJOS DE Zn o Se

Se presentan los resultados obtenidos de la caracterización óptica por medio de la técnica de Fotorreflectancia (FR) y Auger de heteroestructuras de CdTe/GaAs crecidas por epitaxia de haces moleculares (Molecular Beam Epitaxy, MBE). Las películas de CdTe fueron crecidas sobre substratos de GaAs con espesores nominales de 100 Å. Cada una de estas películas fue expuesta separadamente a flujos de Zn o Se. El cambio en la forma de línea y el incremento de la señal en los puntos críticos E0 y E0+ Δ 0 en el espectro de FR del GaAs es un indicativo de la reactividad que se presenta en la superficie de la heteroestructura de CdTe/GaAs

Effect of Boriding on the Mechanical Properties of AISI 1045 Steel

Efecto en las propiedades mecánicas de un acero borurado 1045.Some mechanical properties of AISI 1045 borided steels were estimated in the present work. The boriding process was carried out by the powder pack method at 950°C with 8 h of treatment. The fatigue strength on borided notched specimens was evaluated with rotating bending tests (R=1) considering a stress concentration factor (Kt) of 2.53. Likewise, the presence of residual stresses in boride layers was established by the XRD technique. The Daimler-Benz Rockwell C test was used, also, to estimate the strength adhesion of the coated system. The results show a decrease in the fatigue strength of AISI borided steels due to the presence of high porosity in the layers. Finally, the Rockwell-C adhesion test showed no coating failure for the boride layer

Internet-enabled lab-on-a-chip technology for education

Despite many interventions, science education remains highly inequitable throughout the world. Internet-enabled experimental learning has the potential to reach underserved communities and increase the diversity of the scientific workforce. Here, we demonstrate the use of lab-on-a-chip (LoC) technologies to expose Latinx life science undergraduate students to introductory concepts of computer programming by taking advantage of open-loop cloud-integrated LoCs. We developed a context-aware curriculum to train students at over 8000 km from the experimental site. Through this curriculum, the students completed an assignment testing bacteria contamination in water using LoCs. We showed that this approach was sufficient to reduce the students' fear of programming and increase their interest in continuing careers with a computer science component. Altogether, we conclude that LoC-based internet-enabled learning can become a powerful tool to train Latinx students and increase the diversity in STEM

Association of the microsatellite in the 3' untranslated region of the CD154 gene with rheumatoid arthritis in females from a Spanish cohort: a case-control study

CD40–CD154 interaction is an important mediator of inflammation and has been implicated in T helper type 1-mediated autoimmune diseases including rheumatoid arthritis (RA). Linkage studies have shown association of markers in the proximity of the CD154 gene. In the present work we investigated whether specific allele variants of the microsatellite in the 3' UTR of the CD154 gene might modulate the risk of RA. The study, in a case-control setting, included 189 patients and 150 healthy controls from the Canary Islands, Spain. The 24CAs allele was less represented in female patients than in controls (0.444 in controls versus 0.307 in patients, P = 0.006, odds ratio (OR) 0.556, 95% confidence interval (CI) 0.372 to 0.831) but not in males (0.414 versus 0.408), and only when homozygous (P = 0.012; OR 0.35, 95% CI 0.16 to 0.77). We also verified that CD154 association with RA was independent of human leukocyte antigen (HLA) phenotype. A further functional study showed that after stimulation anti-CD3, CD154 mRNA was more stable in CD4+ T lymphocytes from patients with RA bearing the 24CAs allele (mRNA half-life 208 minutes) than in patients without the 24CAs allele (109 minutes, P = 0.009). However, a lower percentage of CD154+CD4+ T lymphocytes was seen in freshly isolated peripheral blood mononuclear cells from patients carrying 24CAs alleles (mean 4.28 versus 8.12; P = 0.033), and also in CD4+ T lymphocytes stimulated with anti-CD3 (median 29.40 versus 47.60; P = 0.025). These results were concordant with the smaller amounts of CD154 mRNA isolated from stimulated T lymphocytes with 24CAs alleles. The CD154 microsatellite therefore seems to affect the expression of the gene in a complex manner that implies not only mRNA stability. These data suggest that the CD154 microsatellite contributes to the regulation of mRNA and protein expression, although further studies will be necessary to elucidate its role in disease predisposition

Bioética. El final de la vida y las voluntades anticipadas

Esta obra contiene textos elaborados por investigadores de diferentes áreas del conocimiento: medicina, filosofía, derecho, entre otras especialidades, pertenecientes a distintos países: España, Chile y México. El objetivo principal de este libro es servir de referente teórico a otros investigadores de bioética, y especialmente a los que son o desean estar especializados en la comprensión del final de la vida y las voluntades anticipadas en el ámbito sanitario en cualquier país del mundo