La Empresariabilidad en Prestadores de Servicios Profesionales Agropecuarios del Estado de Campeche, México

La empresarialidad definida como la capacidad o competencia para generar y crear nuevas iniciativas empresariales tiene su relevancia en el desarrollo territorial y económico. Por lo que los gobiernos estatales buscan apoyar a los productores agropecuarios en el desarrollo de sus competencias empresariales basados en una red de prestadores de servicios profesionales (PSP). El objetivo del artículo fue analizar la construcción del concepto de empresarialidad derivado de auto-percepciones (actitudes positivas) y características de los PSP del medio agropecuario (edad y años como prestadores). Se aplicó un cuestionario con 60 afirmaciones evaluadas en una escala de Likert de 0 a 6, a 105 PSP del estado de Campeche, México; de los que sólo se retuvieron 71 observaciones completas y validas y con las cuales se generó un índice de empresarialidad. El índice se obtuvo como la suma de los valores individuales de cada reactivo, donde 0 era el mínimo y 360 el máximo posible (M= 279.23, DS= 35.30, Min= 62, Max= 339). A fin de reducir el número de variables, frases que reflejaban actitudes positivas y que explicaban el índice de empresarialidad, se realizó un análisis factorial obteniéndose 14 constructos, se conservaron dos frases independientes, así como la edad y el número de años como PSP, para ser utilizados en un análisis de regresión jerárquica. Los resultados muestran que las variables de persistencia, innovación, autoestima, independencia, compromiso, y preferir estar sólo, así como otras características están positiva y significativamente asociadas con mayores niveles de empresarialidad (pmenor que0.001), mientras que las variables que no explicaron la misma fueron el riesgo y tomar la iniciativa. La edad y los años de experiencia no estuvieron significativamente asociados con mayores niveles de empresarialidad. Por lo que se concluye que las actitudes positivas son importantes para explicar la autopercepción de empresarialidad, mientras que esta última no depende de la edad de los sujetos. La consecuencia del estudio para los gobiernos estatales radica en fomentar proyectos productivos que impliquen el desarrollo de competencias relacionadas con ser emprendedor, ya que se logran actitudes positivas en los actores locales que repercutirán en una mayor competitividad

Electronic structure and properties of (TiZrNbCu)_1-xNi_x high entropy amorphous alloys

A comprehensive study of selected properties of four (TiZrNbCu)_1-xNi_x (x \le 0.25) amorphous high entropy alloys (a-HEA) has been performed. The samples were ribbons about 20 \mum thick and their fully amorphous state was verified by X-ray diffraction and thermal analysis. The surface morphology, precise composition and the distribution of components were studied with a Scanning electron microscope (SEM) with an energy dispersive spectroscopy (EDS) attachment. The properties selected were the melting temperature (T_m), the low temperature specific heat (LTSH), the magnetic susceptibility \chi_exp and the Young^,s modulus (E). Whereas LTSH and \chi_exp were measured for the as-cast samples, E was measured both for as-cast samples and relaxed samples (after a short anneal close to the glass transition temperature). The LTSH showed that the electronic density of states at the Fermi level, N_0(E_F), decreases with increasing x, whereas the Debye temperature (\theta_D) increases with x. This is similar to what is observed in binary and ternary amorphous alloys of early transition metals (TE) with late transition metals (TL) and indicates that N_0(E_F) is dominated by the d-electrons of the TE. The LTSH also showed the absence of superconductivity down to 1.8K and indicated the emergence of the Boson peak above 4K in all alloys.The free-electron like paramagnetic contribution to \chi_exp also decreases with x, whereas E, like \theta_D, increases with x, indicating enhanced interatomic bonding on addition of Ni. The applicability of the rule of mixtures to these and other similar HEAs is briefly discussed

Reconocimiento geológico y métodos de estabilización de taludes rocosos en formaciones volcánicas del sur de Gran Canaria y Fuerteventura, Islas Canarias.

El relieve natural de las islas volcánicas montañosas tiene profundos barrancos taludes rocosos de pronunciadas pendientes y elevados acantilados costeros. Las formaciones geológicas de origen volcánico incluyen materiales rocosos y suelos muy heterogéneos en cuanto a su disposición espacial y comportamiento geomecánico. Además, en las zonas del sur de Gran Canaria y Fuerteventura, con frecuencia las construcciones civiles y de edificación muestran altos taludes practicados en el terreno y, como resultado en diversos puntos se ven afectados por desprendimientos de rocas y deslizamientos En el presente trabajo se muestran dos casos de estudio: 1) Estudio del riesgo de desprendimientos de rocas y métodos de estabilización aplicados en el talud de Los Teques, T.M. de Mogán, sur de Gran Canaria, y 2) Estudio geológico-geotécnico para el proyecto de construcción del paseo peatonal en el acantilado costero de Morro Jable T.M. de Pájara, sur de Fuerteventura. La variación espacial de las formaciones volcamcas, su grado de soldadura y alteración variables y la dificultad de establecer familias de fracturas características, han hecho que los métodos clásicos de clasificación geomecanica resultaran poco eficaces. En estos casos, el reconocimiento geológico detallado y una estimación del comportamiento geomecánico de los materiales ha sido el método empleado para definir y evaluar las zonas inestables en los taludes y para establecer los métodos de estabilización más convenientes

Production of al foams using the SDP method: Processing parameters and introduction of a new sintering device

The processing of aluminum (Al) foams with maximum porosity of around 70 %, regular pore size and interconnected pores were successfully produced by means of the powder metallurgy method of Sintering Dissolution Process (SDP). The metal powder used for the present study was Al powder with 99.5 % of purity and diameters between 75 μ m and 200 μ m. The chosen Space Holder Particles (SHP) were spherical carbamide CH4N2O particles with diameters ranging from 1 to 2 mm. The optimum sinterization temperature was found at 620 °C, at this temperature, a number of necks between Al particles surfaces were observed; indicating a good cohesion between Al particles, while keeping the porous structure of the green compact. The level of porosity was dependent of the carbamide content and the voids formed within the Al particles after the sinterization process. The sample with 60 wt.% of carbamide showed the lowest yield stress value than those for the samples with 40 and 50 wt.%. The strain values significantly increased when the carbamide content increased from 40 to 60 wt.%. Finally, the results obtained from a new sintering device for producing metallic foams at temperatures below 900 °C are also discussed

Microstructure and texture evolution of the Al-20sn alloy processed by equal-channel angular pressing using route C

In this work, the microstructure and texture evolution of an Al-20Sn (mass%) alloy processed by Equal Channel Angular Pressing is presented. The evolution of dislocation cells into subgrains and the mechanical response of the deformed alloy have been emphasized. Samples were characterized by transmission electron microscopy, X-ray diffraction (for microstrain and texture measurements) and Vickers microhardness. It was found, that Al grains, suffered the highest degree of deformation during the ECAP process, however, the evidence showed that the deformation was largely heterogeneous, in terms of crystalline domain and feasibly in misorientation angles. The initial copper texture changes throughout the ECAP process forming an incipient shear texture component (111)[11-2]. The heterogeneity of the results obtained from the Vickers microhardness mapping could be associated to the microstructure resulted after the ECAP process. © 2014 The Japan Institute of Metals and Materials

Texture and Lattice Distortion Study of an Al-6061-T6 Alloy Produced by ECAP

Equal channel angular pressing (ECAP) is a severe plastic deformation (SPD) technique that produces nanostructured materials. Based on a remarkable grain size reduction, this process has led to improve mechanical properties, such as yield strength, fatigue, UTS, etc. In this work the characterization of the microstructure of the aluminum 6061-T6 alloy; plastically deformed up to ε ≈ 6, by the ECAP process, following route Bc, is presented. For this purpose, the ECAP processed samples were characterized by means of X-ray diffraction (for texture and line profile analysis) and transmission electron microscopy. The initial crystallographic texture vanished after one ECAP pass and a new, well defined, shear texture Cθ was generated. For the subsequent ECAP passes, more shear components: A1θ *, Bθ and \bar{B}θ were also developed. From the orientation distribution function analysis, a shift (generally less than 15°) between some experimental maxima and the reported ideal shear texture positions was observed. From these results, it was found that the microstructure generated with this process was stabilized after the 5th ECAP pass. Finally, the micro-strain analyses, in addition to the texture and transmission electron microscopy, contributed to the understanding of the effect of the physical and mechanical processes that were activated during the SPD-ECAP technique

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