Bending strength and stiffness of structural laminated veneer lumber manufactured from fast-growing argentinean Eucalyptus grandis

The present paper reports the results of an investigation regarding the determination of bending strength and stiffness in specimens of laminated veneer lumber (LVL) manufactured from Argentinean Eucalyptus grandis and tested edgewise according to European standards. For this purpose an empirical research project with one sample containing 44 specimens with nominal sizes of 24.3 mm in width, 100 mm in depth and 2.44m in length was carried out. The characteristic strength value was 74 % and 118 % higher, respectively, than those adopted by Argentinean standards for the best strength class of sawn and glued laminated timber of the same species. It was similar to that reported for LVL of Norway spruce and lower than that published for LVL made from Uruguayan Eucalyptus grandis even though in the latter case the reported value was not obtained according to European standards. The modulus of elasticity mean value was 22 % and 14 % higher, respectively, than those adopted by Argentinean standards for the best strength class of sawn and glued laminated timber of the same species. Modulus of elasticity also exhibited a mean value 22 % and 53 % higher, respectively, than those published for LVL manufactured from Norway spruce and Uruguayan Eucalyptus grandis. A relatively low variation of results was found for both strength (COV = 9 %) and modulus of elasticity (COV = 10 %) and the particularly high stiffness/density relation previously published for sawn timber of this Argentinean deciduous species was confirmed by the results of this study. The coefficient of determination (R2) between density and modulus of elasticity was equal to 0.67 whereas R2 reached 0.37 between modulus of elasticity and strength and 0.19 between density and strength

Bending strength and stiffness of poles of argentinean Eucalyptus grandis

The present paper reports the results of an investigation regarding the determination of bending strength and stiffness in full-size poles of Argentinean Eucalyptus grandis. The importance of accura-tely knowing the mechanical properties of this material has increased with the increasing demand of utility poles of this species and with the use of modern procedures aimed at achieving a reliable and economical structural design. For this purpose an empirical research project with two samples contai-ning new, green, untreated poles was carried out according to the procedures adopted by both the Ame-rican standard ASTM D 1036 (2005) and the Argentinean standard IRAM 9529 (2004) for cantilever bending tests. Sample 1 enclosed 14 year-old poles with nominal length of 12 m and Sample 2 enclosed 11 year-old poles with nominal length of 8 m. The results found for the average circumference taper were similar to the values adopted by the American standard ANSI 05.1 (2002) and knot dimensions as well as knot ratio compared well with those permitted by this standard. The mean value found for maximum fi bre stress at ground line reached 62.9 N/mm2 for Sample 1 and 56.3 N/mm2 for Sample 2. These strength results are relatively high in comparison with values reported for seasoned sawn timber of the same species and they compare well with those published by the American standard ANSI 05.1c (2004) for poles of different species. Both samples showed a coeffi cient of variation of 13 % for streng-th at ground line which is relatively low in comparison with those adopted by the American standard and may be considered an advantage of this material for structural purposes. The mean value found for modulus of elasticity reached 10935 N/mm2 for Sample 1 and 9546 N/mm2 for Sample 2, with a coeffi cient of variation of 14 % for both cases. Results also revealed signifi cant differences between mechanical properties values corresponding to the two samples containing poles with different sizes and age. The correlation coeffi cient between knot ratio and strength showed the insignifi cant values of 0.09 and 0.02 for Sample 1 and 2 respectively, and the corresponding results between modulus of elasticity and strength were 0.52 and 0.37.En el presente trabajo se presentan los resultados de una investigación orientada a determinar la resistencia y la rigidez de postes de Eucalyptus grandis de Argentina. La importancia de conocer con precisión las propiedades mecánicas de este material cobró mayor relevancia con la creciente demanda de postes de esta especie y con la adopción de modernos procedimientos de cálculo orientados a lograr un diseño estructural confi able y económico. Con este fi n se llevó a cabo un proyecto empírico que abarcó dos muestras de postes en tamaño estructural, nuevos y sin tratamientos, los cuales se ensayaron en estado verde conforme a los procedimientos establecidos en la norma estadounidense ASTM D 1036 (2005) y en la Argentina IRAM 9529 (2004) para pruebas en voladizo. La muestra 1 incluyó postes con 12 m de longitud nominal y una edad de 14 años, y la muestra 2 estuvo compuesta por postes con 8 m de longitud nominal y una edad de 11 años. Los valores promedio encontrados para la conicidad fueron similares a los adoptados por la norma ANSI 05.1 (2002) y tanto el tamaño de los nudos como la nudosidad compararon bien con los valores permitidos por esta norma. El valor medio de la tensión de rotura en la línea de empotramiento fue de 62,9 N/mm2 para la Muestra 1 y de 56,3 N/mm2 para la Muestra 2. Estos resultados son relativamente altos en comparación con los publicados para madera aserrada de la misma especie ensayada en estado seco y son comparables a los adoptados por la norma ANSI 05.1c (2004) para postes de diferentes especies. Ambas muestras exhibieron un coefi ciente de variación de 13 % para la resistencia en la línea de empotramiento, valor que es relativamente bajo en comparación con los adoptados por la norma estadounidense y puede ser considerado una ventaja del material para uso estructural. El valor medio del módulo de elasticidad alcanzó 10935 N/mm2 para la muestra 1 y 9546 N/mm2 para la muestra 2, con un coefi ciente de variación de 14 % en ambos casos. Los resultados también pusieron de manifi esto diferencias signifi cativas entre los valores de las pro-piedades mecánicas de ambas muestras, integradas por postes de diferentes edades y dimensiones. El coefi ciente de correlación entre la nudosidad y la resistencia alcanzó los insignifi cantes valores de 0,09 para la muestra 1 y de 0,02 para la muestra 2, mientras que los valores correspondientes entre el módulo de elasticidad y la resistencia fueron 0,52 y 0,37

Spin-Parity Analysis of the Centrally produced KsKs system at 800 GeV

Results are presented of the spin-parity analysis on a sample of centrally produced mesons in the reaction (p p -> p_{slow} K_s K_s p_{fast}) with 800 GeV protons on liquid hydrogen. The spin-parity analysis in the mass region between threshold and 1.58 GeV/c^2 shows that the (K_s K_s) system is produced mainly in S-wave. The f_0(1500) is clearly observed in this region. Above 1.58 GeV/c^2 two solutions are possible, one with mainly S-wave and another with mainly D-wave. This ambiguity prevents a unique determination of the spin of the f_J(1710) meson.Comment: 6 pages, including 6 figures. LaTex, uses 'espcrc2.sty'. To appear in LEAP'96 proceeding

Altibajos de la expansión algodonera hacia nuevas áreas, una mirada retrospectiva

Desde la campaña algodonera 2012/13 y hasta la actual 2014/15 se continúan con los estudiosexploratorios del proyecto que lleva adelante el INTA Reconquista y APPA (Asociación para la Promoción de la Producción de Algodón) con la fuerte colaboración del sector privado, con el fin de generar información de las características suelo-planta-ambiente y sus relaciones, para lograruna producción de algodón sustentable, adaptado a las condiciones agroecológicas de los Bajos Submeridionales y zona de transición hacia el Domo Occidental de Santa Fe.Fil: Paytas, Marcelo Javier. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Mieres, Luciano Nicolás. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Szwarc, Diego Ernesto. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Sosa, M.A. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Vitti Scarel, Daniela Elizabeth. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Almada, Melina Soledad. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bianchi, Enzo Dario. No especifíca;Fil: Sager, Guillermo. No especifíca

Comportamiento productivo e indicadores de bienestar en pollos de engorda en pastoreo

Objective: To evaluate the productive performance and welfare indicators of pastured broiler chickens. Methodology: One hundred sixty-eight straight-run broilers Ross 308 of 33 d of age were randomly assigned to two treatments: T1, confinement with ad libitum feeding and T2, system with eight hours of pasture access and concentrated feed restricted to 40% of the consumption of T1 chickens. Productive performance from 33 to 54 d of age, walking ability (Hc), latency to lie down (Lp), foot pad lesions (Qp), valgus/varus angulation (AngV), tendon breaking strength (RRTe) and tibia breaking strength (RRTi), were evaluated. Results: Productive performance between treatments was different (P < 0.05). Chickens in T1 had a higher live weight at 54 d of age (3,379 ± 39 g) than T2 (2,223 ± 39 g). Likewise, feed conversion ratio from 33 to 54 d of age was lower in confined birds (2.05 ± 0.05 g/g) than in pastured chickens (2.28 ± 0.05 g/g). These latter birds showed a better (P < 0.05) Hc and Lp, but no differences were detected between treatments (P ? 0.05) for AngV, Qp and RRTe. Implications of the study: The results are only valid for straight-run Ross 308 broiler chickens and under the specified management conditions. Conclusion: Pasture-raised broiler chickens with restricted consumption of concentrated feed, have better welfare indicators (Hc and Lp), but worse productive performance.Objetivo: Evaluar el comportamiento productivo e indicadores de bienestar de pollos de engorda en pastoreo. Metodología: Se utilizaron 168 pollos mixtos Ross 308 de 33 d de edad, que se asignaron al azar a dos tratamientos: T1, crianza en confinamiento con alimentación ad libitum y T2, sistema con ocho horas de pastoreo y ración de concentrado restringida al 40% del consumo de los pollos del T1. Se evaluó el comportamiento productivo de 33 a 54 d de edad, habilidad para caminar (Hc), latencia a postrarse (Lp), quemadura de almohadillas plantares (Qp), angulación valgus/varus (AngV), resistencia a la ruptura del tendón gastrocnemio (RRTe) y de la tibia (RRTi). Resultados: El comportamiento productivo entre tratamientos fue diferente (P < 0.05). Los pollos en T1 tuvieron mayor peso vivo a 54 d de edad (3,379 ± 39 g) que T2 (2,223 ± 39 g). Asimismo, la conversión alimenticia  de 33 a 54 d de edad fue menor en aves confinamiento (2.05 ± 0.05 g/g) que en pastoreo (2.28 ± 0.05 g/g). Estas últimas mostraron una mejor (P < 0.05) Hc y Lp, pero no se detectaron diferencias entre tratamientos (P ? 0.05) para AngV, Qp y RRTe.    Implicaciones del estudio: Los resultados obtenidos sólo son válidos para pollos de engorda mixtos Ross 308 y bajo las condiciones de manejo especificadas.   Conclusión: El pastoreo con restricción del consumo de concentrado, mejora los indicadores de bienestar Hc y Lp, pero afecta el comportamiento productivo

Social Cohesion, Structural Holes, and a Tale of Two Measures

EMBARGOED - author can archive pre-print or post-print on any open access repository after 12 months from publication. Publication date is May 2013 so embargoed until May 2014.This is an author’s accepted manuscript (deposited at arXiv arXiv:1211.0719v2 [physics.soc-ph] ), which was subsequently published in Journal of Statistical Physics May 2013, Volume 151, Issue 3-4, pp 745-764. The final publication is available at link.springer.com http://link.springer.com/article/10.1007/s10955-013-0722-

Characterization of six microsatellite loci in Myrica faya (Myricaceae) and cross amplification in the endangered endemic M. rivas-martinezii in Canary Islands, Spain

Six novel polymorphic microsatellite markers were isolated from enriched libraries in Myrica faya Ait., recently renamed Morella faya, (fayatree, firetree, or firebush) in order to examine the genetic diversity in natural populations. Also, test cross-specific amplification and genetic diversity in Myrica rivas-martinezii, which is endemic on the Canary islands. Microsatellite loci were screened in 225 individuals of both species from different islands of the Canarian archipelago. All markers were successfully amplified from both Myrica species, with an average number of 6.5 and 9.3 alleles per locus in M. rivas-martinezii and M. faya, respectively. There was no evidence for linkage disequilibrium between loci, and the probability of null alleles ranged from 0.01 to 0.17