Revealing the nature of magnetic shadows with numerical 3D-MHD simulations

We investigate the interaction of magneto-acoustic waves with magnetic network elements with the aim of finding possible signatures of the magnetic shadow phenomenon in the vicinity of network elements. We carried out three-dimensional numerical simulations of magneto-acoustic wave propagation in a model solar atmosphere that is threaded by a complexly structured magnetic field, resembling that of a typical magnetic network element and of internetwork regions. High-frequency waves of 10 mHz are excited at the bottom of the simulation domain. On their way through the upper convection zone and through the photosphere and the chromosphere they become perturbed, refracted, and converted into different mode types. We applied a standard Fourier analysis to produce oscillatory power-maps of the line-of-sight velocity. In the power maps of the upper photosphere and the lower chromosphere, we clearly see the magnetic shadow: a seam of suppressed power surrounding the magnetic network elements. We demonstrate that this shadow is linked to the mode conversion process and that power maps at these height levels show the signature of three different magneto-acoustic wave modes.Comment: Astronomy & Astrophysics Letters, in print 4 pages, 4 figure

MANEJO DO CRESCIMENTO DIAMÉTRICO DE Araucaria angustifolia (Bert.) O. Ktze. BASEADO NA ÁRVORE INDIVIDUAL

Neste trabalho, foi analisado o potencial do crescimento diamétrico de Araucaria angustifolia (Bert.) O. Ktze. em diferentes sítios, com o objetivo de obter informações para o manejo dessa espécie em florestas heterogêneas inequiâneas, visando à produção de madeira de alta qualidade em árvores pré-selecionadas. O material usado constitui-se de 400 árvores de florestas nativas e plantios, crescendo sob condições e tratamentos variáveis nos estados de Santa Catarina, Paraná e Rio Grande do Sul. O método usado para investigar a relação entre a largura da copa e o dap foi baseado na projeção horizontal da copa da árvore individual. Usando 16 amostras de 25 árvores, foram estudados vários estágios de desenvolvimento. Para cada amostra, foi feito um mapa de distribuição das árvores e das projeções das copas para avaliar o efeito da competição. O estudo mostra que existe uma estreita relação entre a largura da copa e o dap, que pode ser usada para o desenvolvimento de novas ferramentas de decisão aplicáveis em árvores individuais para o manejo de araucária em florestas heterogêneas inequiâneas ou para a produção de madeira de alta qualidade com árvores pré-selecionadas. Também, mostrou-se uma estreita correlação entre o crescimento de diâmetro e a qualidade do sítio, pois a expansão máxima da copa depende da qualidade deste, indicando que ele deve ser considerado como fator limitante para o manejo do crescimento

Modelos de producción de madera sólida en plantaciones de Eucalyptus globulus de Galicia

El objetivo de este trabajo es establecer las interacciones existentes entre crecimiento diametral, crecimiento en altura y la dinámica de poda natural de Eucalyptus globulus con el objetivo de evaluar la eficiencia de distintas opciones de gestión forestal para producir madera de alta calidad. Para ello se ha desarrollado un modelo de crecimiento basados en el árbol individual. La toma de muestras comprende más de 900 Eucalyptus globulus medidos en diferentes localizaciones de Galicia (España). En esos árboles se ha encontrado una elevada correlación significativa entre el diámetro normal y el diámetro de la copa. El modelo basado en el ancho de copa permite calcular el espacio vital requerido por un árbol para alcanzar un diámetro predefinido a una cierta edad. Una vez conocido, es también posible calcular el número de árboles por hectárea así como el momento y la intensidad de las claras. Se ha podido comprobar que los eucaliptos orientados a la producción de madera aserrada en rotaciones cortas tienen que podarse y, dada la tendencia de los árboles a incluir el tocón de las ramas muertas, es recomendable realizar la poda mientras las ramas todavía están verdes. Para optimizar la producción de madera limpia, es esencial conocer el impacto de los tratamientos silvícolas y condiciones de crecimiento en el proceso de formación de la base de la copa. Se ha encontrado que la altura de la base de copa viva muestra una buena correlación con el diámetro normal, la altura del árbol y la edad. Empleando estas tres variables se ha desarrollado un modelo multivariable para predecir la altura de la primera rama viva, que puede ser de utilidad para optimizar el momento y la intensidad de las claras para producir madera de sierra de eucalipto en plantaciones de corta rotación._________________________________The study aims to point out the interactions between diameter and height growth and the self-pruning dynamics of Eucalyptus globulus in order to evaluate different management regimes according to their efficiency for high value timber production. Therefore a growth model for individual trees has been developed. The database contains over 900 trees of Eucalyptus globulus measured at different sites in Galicia / Spain. For these trees a significant relationship between diameter at breast height (d1,3) and crown diameter calculated from this area was found. The crown width model enables us to calculate the growing space needed by a tree to get a pre-defined diameter at a given age. Knowing this, it is also possible to calculate the number of trees/ha as well as time and intensity of thinning interventions. It could be shown that eucalypt grown for sawlogs in short rotations have to be pruned. Since the trees tend to include dead branches partly into the bole, it is recommendable to prune branches when still green. In order to optimize production of knot free timber, it is essential to know the impact of silvicultural treatments and growth conditions on the process of living crown base recession. It was found that height of living crown base shows good correlations with d1,3, tree height and age. Using these 3 variables a multivariate model for predicting height of the first living branch has been developed, which may be helpful to optimize time and intensity of pruning for eucalypt sawlog production in short rotation plantations

Manejo do crescimento em diâmetro da árvore individual e o impacto para a poda de Eucalyptus grandis no Brasil.

No presente estudo, foi desenvolvido um programa de desbaste e um modelo para a descrição da dinâmica da base da copa. Para esse fim, 485 árvores foram medidas em parcelas temporárias das empresas Klabin Riocell (Guaíba, hoje Aracruz), Todeschini (Cachoeira do Sul), Universidade Federal de Santa Maria (RS) e Aracruz Celulose (Espirito Santo e Bahia). Foi encontrada uma correlação linear entre a largura da copa e o diâmetro à altura do peito (DBH), usando-se a metodologia da análise de regressão. A equação obtida foi largura da copa = e0.504+0.0307* DBH, com um coeficiente de determinação de 0.78 e um erro padrão de 0.034. Com esse modelo, foi calculado o espaço da árvore individual necessário para alcançar um determinado crescimento em diâmetro durante todo o ciclo de rotação, considerando uma cobertura do dossel média de 70%. Assim, o número de árvores por hectare em diferentes estágios de desenvolvimento foi calculado para diferentes sistemas de manejo com o objetivo de produzir madeira para serraria em ciclos de rotações curtas. Também foi obtido um modelo multivariado descrevendo a altura da base da copa viva em função das variáveis diâmetro à altura do peito (DBH) e altura total. Com base nesses modelos, a dinâmica na inserção da copa viva para diferentes sistemas de manejo em sítios de diferentes qualidades pode ser calculado, possibilitando assim a determinação do ponto ótimo e da intensidade da poda.In the present work a thinning program and a model describing dynamic of crown base recession for Eucalyptus grandis was established on an individual tree basis. Therefore, 485 trees were measured on temporary plots in forests of the companies Klabin Riocell (Guaíba), Todeschini (Cachoeira do Sul), the Federal University of Santa Maria and Aracruz Company, located in Rio Grande do Sul, Espirito Santo and Bahia, Brazil. A straight relationship between crown width and diameter at breast height (DBH) was found by using regression analysis. The equation obtained was crown width = e0.504+0.0307* DBH, with a coefficient of determination of 0.78 and a standard error of 0.034. With this equation the standing space of the individual trees was calculated over the whole rotation period, taking into account a crown cover of 70 %. Therefore the number of trees which can be grown on a hectare was derived for different variants of management systems aiming to produce eucalypt sawlogs in short rotation periods. Beside this a multivariate model describing height of crown base as a function of DBH and total height was found. Based upon this model the dynamics of crown base recession for different site qualities and thinning regimes are described, giving advice for time and intensity of green pruning

MODELAGEM DA DESRAMA NATURAL DE Araucaria angustifolia (BERT.) O. KTZE

Neste trabalho foi analisada a dinâmica e a qualidade da desrama natural de Araucaria angustifolia (Bert.) O. Ktze. em diferentes sítios no Sul do Brasil, dentro de uma estratégia da produção de madeira de alta qualidade. O material usado se constitui de 400 árvores de florestas nativas e plantadas, crescendo sob variadas condições e tratamentos. O método usado foi a análise exploratória dados levantados de parcelas temporárias. Foram feito mapas de distribuição das árvores e das projeções das copas para avaliar a competição e o seu efeito na desrama. O estudo mostra que existe uma relação estreita entre o crescimento em altura e diâmetro, numa idade determinada, e a inserção da copa. O primeiro galho morto está estreitamente ligado com a inserção da copa. Estas variáveis foram usadas para modelar o desenvolvimento da inserção da copa e da altura comercial ao longo do tempo. Além disso, podem ser derivados destes modelos a dimensão do núcleo enodado. Foi mostrado que para o manejo de araucaria em rotações curtas uma poda artificial aumenta significativamente à parte da madeira valiosa sem nós. MODELLING SELF-PRUNING OF ARAUCARIA ANGUSTIFOLIA (BERT.) O. KTZE Abstract In the present study the self-pruning dynamics and quality of Araucaria angustifolia (Bert.) O Ktze. on different sites in Southern Brazil was analyzed in the framework of a strategy of high quality wood production. The material consisted of 400 trees from native forests and plantations growing under varying site conditions and treatments in the Brazilian states of Santa Catarina, Parana and Rio Grande do Sul. The research method applied was an explorative analysis of data taken from temporary sample plots. For each plot stem distribution and crown projection map was established in order to determine the competition status and its impact on self-pruning. The study shows that diameter and height at a certain age are good estimators for predicting height of crown base. The lowest dead branch is closely related to crown base. These parameters are used to model the dynamics of self-pruning depending on radial increment and height growth. Moreover, the dimension of the knotty core was calculated. It could be shown that Araucaria angustifolia has a retarded self-pruning because of its tendency of maintaining dead branches at the stem. Especially for target diameters of 40 to 50 cm within short rotation periods an artificial pruning is recommended in order to reduce the knotty core

The UNSW Extrasolar Planet Search: Methods and First Results from a Field Centred on NGC 6633

We report on the current status of the University of New South Wales Extrasolar Planet Search project, giving details of the methods we use to obtain millimagnitude precision photometry using the 0.5m Automated Patrol Telescope. We use a novel observing technique to optimally broaden the PSF and thus largely eliminate photometric noise due to intra-pixel sensitivity variations on the CCD. We have observed 8 crowded Galactic fields using this technique during 2003 and 2004. Our analysis of the first of these fields (centred on the open cluster NGC 6633) has yielded 49 variable stars and 4 shallow transit candidates. Follow-up observations of these candidates have identified them as eclipsing binary systems. We use a detailed simulation of our observations to estimate our sensitivity to short-period planets, and to select a new observing strategy to maximise the number of planets detected.Comment: 16 pages, 9 figures, version published in MNRAS Updated figures, references, and additional discussion in section

MODELING THE EFFECT OF PRUNING AND THINNING ON GROWTH STRAIN OF Eucalyptus globulus Labill.

Se estudi\uf3 una plantaci\uf3n de Eucalyptus globulus ubicada en el sector precordillerano andino de la regi\uf3n del B\uedo B\uedo, Chile, con el objetivo de evaluar y modelar el efecto de la poda y raleo sobre las deformaciones residuales longitudinales (DRL). El lugar de estudio correspondi\uf3 a un rodal de 12 a\uf1os de edad, el cual fue intervenido a los 2 a\uf1os y medio de establecido, donde se evaluaron distintas intensidades de poda (0% y 60% de la altura total) y densidades de raleo (1.600 \ue1rb\ub7ha-1 (sin raleo) y 800 \ue1rb\ub7ha-1). En cada tratamiento definido por la combinaci\uf3n de los dos niveles de poda y raleo, se estudi\uf3 adem\ue1s, el efecto de la clase de copa (dominante, codominante e intermedia) sobre el comportamiento de las DRL. En cada unidad de muestreo se registraron variables a nivel de \ue1rbol individual, estimando los par\ue1metros de rodal m\ue1s relevantes. Se muestre\uf3 un total de 36 \ue1rboles, midi\ue9ndose en cada uno de ellos las DRL a nivel del Dap con un extens\uf3metro dise\uf1ado por el CIRAD-For\ueat. Los resultados determinaron que la poda y raleo no afectaron significativamente el comportamiento de las DRL en Eucalyptus globulus; en cambio, la clase de copa, tuvo un efecto altamente significativo sobre la variaci\uf3n de las deformaciones residuales, presentando los \ue1rboles dominantes mayores niveles de deformaci\uf3n que las clases de copa codominante e intermedia, respectivamente. El modelo de estimaci\uf3n incluy\uf3 como variables predictivas del comportamiento de las DRL, las expresiones logar\uedtmicas del Dap y del inverso multiplicativo de la varianza de los radios de copa, adem\ue1s de la poda, presentando un R2 de 0,44 y un EEE de 0,132.A 12-year-old Eucalyptus globulus plantation forest was studied with the aim of assessing and modeling the effect of both pruning and thinning activities on the growth strain. The stand is located in the Andean foothills of B\uedo B\uedo region in Chile. Two forest management activities were carried out after 2 and half years from planting, and were evaluated according to different pruning intensities (from 0 to 60 % from total height of the tree) and different thinning densities (800 UPH with thinning and 1.600 UPH without thinning). Furthermore, the effect of the crown classes (dominant, co-dominant and intermediate crown) was studied by the combination of two treatments on the behavior of the growth strain. Each treatment was defined by two levels of pruning and thinning. Data at single-tree level were collected to each sampling unit for estimating the most relevant parameter for the stand. Thirty-three trees in total were sampled. The growth strain was measured at the dbh in each one of them, with an extensometer designed by the CIRAD-For\ueat. The pruning and thinning did not significantly affect the behavior of the growth strain in Eucalyptus globulus according to the research study; on the other hand, the crown class had a highly significant affect on the variation of strains, showing the highest levels of it in dominant crown class trees that trees belonging to co-dominant and intermediate crown classes, respectively. The logarithmic functions and the variance obtained by measurements of dbh, crown radii, and pruning respectively, were entered into regression models as predictor variables of behavior of growth strain, showing a R2 0,44 and a SEE 0,132

MODELACIÓN DEL EFECTO DE LA PODA Y RALEO SOBRE LAS DEFORMACIONES RESIDUALES LONGITUDINALES EN Eucalyptus globulus Labill.

A 12-year-old Eucalyptus globulus plantation forest was studied with the aim of assessing and modeling the effect of both pruning and thinning activities on the growth strain. The stand is located in the Andean foothills of Bío Bío region in Chile. Two forest management activities were carried out after 2 and half years from planting, and were evaluated according to different pruning intensities (from 0 to 60 % from total height of the tree) and different thinning densities (800 UPH with thinning and 1.600 UPH without thinning). Furthermore, the effect of the crown classes (dominant, co-dominant and intermediate crown) was studied by the combination of two treatments on the behavior of the growth strain. Each treatment was defined by two levels of pruning and thinning. Data at single-tree level were collected to each sampling unit for estimating the most relevant parameter for the stand. Thirty-three trees in total were sampled. The growth strain was measured at the dbh in each one of them, with an extensometer designed by the CIRAD-Forêt. The pruning and thinning did not significantly affect the behavior of the growth strain in Eucalyptus globulus according to the research study; on the other hand, the crown class had a highly significant affect on the variation of strains, showing the highest levels of it in dominant crown class trees that trees belonging to co-dominant and intermediate crown classes, respectively. The logarithmic functions and the variance obtained by measurements of dbh, crown radii, and pruning respectively, were entered into regression models as  predictor variables of  behavior of growth strain, showing a R2 0,44 and a SEE 0,132.El lugar de estudio correspondió a un rodal de 12 años de edad, el cual fue intervenido a los 2 años y medio de establecido, donde se evaluaron distintas intensidades de poda (0% y 60% de la altura total) y densidades de raleo (1.600 árb·ha-1 (sin raleo) y 800 árb·ha-1). En cada tratamiento definido por la combinación de los dos niveles de poda y raleo, se estudió además, el efecto de la clase de copa (dominante, codominante e intermedia) sobre el comportamiento de las DRL. En cada unidad de muestreo se registraron variables a nivel de árbol individual, estimando los parámetros de rodal más relevantes. Se muestreó un total de 36 árboles, midiéndose en cada uno de ellos las DRL a nivel del Dap con un extensómetro diseñado por el CIRAD-Forêt. Los resultados determinaron que la poda y raleo no afectaron significativamente el comportamiento de las DRL en Eucalyptus globulus; en cambio, la clase de copa, tuvo un efecto altamente significativo sobre la variación de las deformaciones residuales, presentando los árboles dominantes mayores niveles de deformación que las clases de copa codominante e intermedia, respectivamente. El modelo de estimación incluyó como variables predictivas del comportamiento de las DRL, las expresiones logarítmicas del Dap y del inverso multiplicativo de la varianza de los radios de copa, además de la poda, presentando un R2 de 0,44 y un EEE de 0,132

Detection of vortex tubes in solar granulation from observations with Sunrise

We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory Sunrise. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. From cross sections through the computational domain of the simulation, we conclude that these `granular lanes' are the visible signature of (horizontally oriented) vortex tubes. The characteristic optical appearance of vortex tubes at the solar surface is explained. We propose that the observed vortex tubes may represent only the large-scale end of a hierarchy of vortex tubes existing near the solar surface.Comment: Astrophysical Journal Letters: Sunrise Special Issue, reveived 2010 June 16; accepted 2010 August

Ergonomic aspects and productivity of different pruning tools for a first pruning lift of Eucalyptus grandis Hill ex Maiden

For the substitution of wood from tropical rainforests pruning of for producing valuable hardwoods in short rotation plantations has become important. Existing tools and ergonomic aspects of pruning were not yet well analysed under these conditions. The objective of the study is to evaluate the productivity and ergonomics of three different pruning tools in a pruning lift up to 3 m in height. The trees used in the study came from an 18-month-old clonal stand planted in a 5.0 x 2.8 m spacing. Two manual pruning tools and an electric shear were tested for productivity by using time studies. Ergonomic aspects were evaluated by two test persons using pulse meter equipment. The highest productivity could be shown for the electric shear (236 trees per working day), followed by the manual shear (196 trees/day) and the handsaw (180 trees/day). The heartbeat rate of the two test persons ranged from a level of âvery hard workâ for the manual tools to âmiddle hardâ and âhard workâ for the electric shear. The workload level to achieve the productivity currently reached in practice using purely manual tools is extremely high, exceeding the permanent working capacity of the operators and leading to physical degradation on the long run.EucalyptusEucalyptus grandi