The spectroscopic orbits and the geometrical configuration of the symbiotic binary AR Pavonis

We analyze optical and near infrared spectra of intermediate and high resolution of the eclipsing symbiotic system AR Pavonis. We have obtained the radial velocity curves for the red and the hot component from the M-giant absorption lines and from the wings of Halpha, H and He II4686 emission profiles, respectively. From the orbital elements we have derived the masses, Mgiant=2.5 and Mhot =1.0 solar masses, for the red giant and the hot component, respectively. We also present and discuss radial velocity patterns in the blue cF absorption spectrum as well as various emission lines. In particular, we confirm that the blue absorption lines are associated with the hot component. The radial velocity curve of the blue absorption system, however, does not track the hot companion's orbital motion in a straightforward way, and its departures from an expected circular orbit are particularly strong when the hot component is active. We suggest that the cF-type absorption system is formed in material streaming from the giant presumably in a region where the stream encounters an accretion disk or an extended envelope around the hot component. The broad emission wings originate from the inner accretion disk or the envelope around the hot star.We also suggest that the central absorption in H profiles is formed in a neutral portion of the cool giant's wind which is strongly concentrated towards the orbital plane. The nebula in AR Pav seems to be bounded by significant amount of neutral material in the orbital plane. The forbidden emission lines are probably formed in low density ionized regions extended in polar directions and/or the wind-wind interaction zone.Comment: 12 pages, 5 figures, accepted by A&

Management discriminant properties in semiarid soils

The physical properties of coarse - textured soils in semiarid regions often deteriorate with use. We hypostatized that the changes in the physical properties of the soil were related to the cropping sistem employed. 5urface sampled of 52 Entic Haplustolls under three diferents uses (24 under continuous cultivation), 18 under rotation wuth grass Ieys (R), and 10 virgin soils M were analyzed for c1ay, silt, organic malter anrd water content, bulk density, compaction and aggregate stability. Data were analyzed statistically using principal components, canonical variables, and discriminant functions. A satisfactory segregation of the soils according to discriminant properties (coarse organic matter, aggregate stability, and suceptibility lo compaction) was obtained. The model developed satisfactory classified the soils under different uses (100% R, 83% e, and 88% V). Principal component analysis also showed that bulck density, compaction, and wet aggregate salability are related lo organic matter content. We conclude that, in the studied region, the lower the ratio of organic matter lo clay + soil content, the more severe the physical deterioration of the soils.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.)Publicado en Soil Science, Vol 163 N°7

Evolution of the symbiotic nova RX Puppis

We present and discuss a hundred year history of activity of the hot component of RX Pup based on optical photometry and spectroscopy. The outburst evolution of RX Pup resembles that of other symbiotic novae whereas at quiescence the hot component shows activity (high and low activity states) resembling that of symbiotic recurrent novae T CrB and RS Oph.Comment: To appear in in M. Hernanz, J. Jose, eds, Classical Novae Explosions, AIP; 5 pages, 2 figure

Evolution of the symbiotic nova RX Puppis

We present and discuss a hundred year history of activity of the hot component of RX Pup based on optical photometry and spectroscopy. The outburst evolution of RX Pup resembles that of other symbiotic novae whereas at quiescence the hot component shows activity (high and low activity states) resembling that of symbiotic recurrent novae T CrB and RS Oph.Comment: To appear in in M. Hernanz, J. Jose, eds, Classical Novae Explosions, AIP; 5 pages, 2 figure

Spin and Center of Mass in Axially Symmetric Einstein-Maxwell Spacetimes

We give a definition and derive the equations of motion for the center of mass and angular momentum of an axially symmetric, isolated system that emits gravitational and electromagnetic radiation. A central feature of this formulation is the use of Newman-Unti cuts at null infinity that are generated by worldlines of the spacetime. We analyze some consequences of the results and comment on the generalization of this work to general asymptotically flat spacetimes.Comment: 20 page

Microstructure and reconstitution of freeze-dried gum Arabic at a range of concentrations and primary drying temperatures

Freeze-drying is an energy intensive unit operation used for the production of dehydrated foods, such as instant coffee and dried fruits, and results in high sensorial, nutritional and reconstitution properties of the final products. Understanding the relationships between operating conditions and product quality is essential to design processes that are energy efficient, whilst producing high quality dried foods. In this work, the properties (microstructure and reconstitution) of freeze-dried gum arabic samples (with initial concentrations ranging between 20 and 60% solids by weight) were evaluated. The materials were dried at three different primary drying shelf temperatures, Ts (- 20, - 30 and - 40 ◦C). Sample temperatures recorded throughout freeze-drying were close to the pre-set Ts, with the exception of the 60% initial concentration system, where the sample was hotter than the shelf by 10–15 ◦C, in particular on increasing Ts. This was attributed to a combination of local temperature and pressure conditions that may have resulted in partial melting of the material. For the 20–50% systems, the properties of the freeze-dried materials were mainly affected by the initial concentration of the system, with increasing initial concentration generally resulting in lower porosities (ranging between 20 and 40%) and higher reconstitution times (ranging between 0.5 and 10min for 95% reconstitution). Pores were generally needle-shaped and <200 μm. Large (200–1800 μm), circular pores were observed in high initial concentration systems, and they were dominant in the microstructure of the freeze-dried 60% sample. The presence of these large bubbles was linked to the partial melting of the material, which enabled its expansion and puffing. For the 60% system, primary drying temperature had a profound effect on the properties of the freeze-dried solid, with samples dried at higher temperature showing higher porosity (e.g. 60–70% for Ts = -¬¬ 20◦C) and faster reconstitution rates (e.g. 3min for 95% reconstitution at Ts = - 20◦C). Overall, this study demonstrates the significance of formulation and shelf temperature on the porous structure of freeze-dried samples, which directly influences product performance

Influencia del ambiente edáfico y la fertilización nitrogenada, en cultivares de trigo diferenciados por su potencial

The purpose of the present study was to evaluate the effect of soil environment on yield and response of three wheat cultivars to fertilization with three doses (0, 40 and 120 kg.ha-1). The differences were analyzed with analysis of variance and Fisher's LSD test. Gross margins of each treatment were calculated. All four factors tested in this experiment (site, environment, cultivar and fertilization) had a significant influence on crop performance. Yield and fertilization response were related to water availability which differed among environments. The yield component that most affected yield was the number of grains per square meter, showing strong variability among treatments (5000 to 15000 g.m-2). These differences produced a wide range of variation in gross margins between environments, where a negative effect of fertilization in the more moisture limited environment could be observed, while in those with less moisture restrictions a positive contribution of fertilization to gross margin was found.El objetivo del trabajo fue evaluar el efecto del ambiente edáfico sobre el rendimiento y la respuesta de tres variedades de trigo a la fertilización nitrogenada a la siembra (dosis 0, 40 y 120 Kg N.ha-1). Las diferencias fueron evaluadas mediante ANOVA doble y LSD de Fisher. Se calcularon los márgenes brutos por tratamiento. Los cuatro factores considerados en el ensayo (sitio, ambiente, cultivar y fertilización) influenciaron significativamente sobre el cultivo. El rendimiento y la respuesta a la fertilización se relacionaron con la disponibilidad de agua que resultó contrastante entre ambientes. El número de granos m2 fue el componente con mayor incidencia sobre el rendimiento variando ampliamente entre tratamientos (desde 5000 a 15000 granos.m-2). Estas diferencias dieron lugar a un amplio rango de variación en los márgenes brutos entre ambientes, comprobándose un efecto negativo de la fertilización en el ambiente con mayores restricciones y una contribución positiva en el margen bruto en los ambientes con menores restricciones hídricas

Estudio de la composición química de las semillas y aceites seminales de Ligustrum lucidum Ait y Ligustrum sinense Lour

The fruits of Ligustrum lucidum Ait and Ligustrum sinense Lour were harvested in Olavarria (Province of Buenos Aires, Argentine). The seeds and extracted oils were analysed for characteristics and composition. The seed contained 8,7-10 and 10,7 % (dry basis), respectively. The physicochemical characteristics of the crude oils were: refractive index 1,4647 and 1,4640 (at 25ºC), iodine value 93,7 and 88,8, saponification index 167 and 154, unsaponifiable matter 11 and 18 %, and free fatty acid content of 4,8 and 9,2 (mg KOH/g), respectively. Gas chromatographic analysis of the oils revealed high levels of oleic acid (57,8 and 51,10%), about 25,1 and 29,6 % of saturated acids, respectively, most of them consisting of palmitic acid, but they have a significant content of acid of more than 18 atoms of carbon. The residual seed meals contained low level of crude protein and of available lysine (2.45, 3.65, g/16g N, respectively). Total and phytic acid phosphorous, calcium, ash, crude fiber, and polysaccharides (non presence of starch) contents are reported.Frutos de Ligustrum lucidum Ait y Ligustrum sinense Lour fueron cosechados en Olavarría (provincia de Buenos Aires, Argentina) y sus semillas separadas en forma manual. Las semillas se agotaron con n-hexano, obteniendo los aceites crudos con rendimientos del 8,7-10% y 10,7 % (base seca), respectivamente. Los aceites crudos se examinaron en sus características fisicoquímicas (Índice de refracción: 1,4647 y 1,4640 (a 25ºC), Indice de iodo: 93,7 y 88,8, Indice de saponificación: 167 y 154, insaponificable: 11 y 18 %, Indice de acidez: 4,8 y 9,2 (mgKOH/g) respectivamente. El análisis por cromatografía gaseosa de los ésteres metílicos reveló alto porcentaje de ácido oleico (57,8 y 51,1%), alrededor de un 25,1 y 29,6 % de ácidos saturados, respectivamente, predominando el ácido palmítico, pero con un significativo contenido de ácidos de más de 18 átomos de carbono. Las harinas residuales de extracción contenían baja proporción de proteína cruda y de lisina disponible. Se informan valores de fósforo total y de ácido fítico, cenizas, calcio, fibra cruda, hidratos de carbono