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Buoyant magnetic flux ropes in a magnetized stellar envelope: Idealized numerical 2.5-D MHD simulations

Context: The context of this paper is buoyant toroidal magnetic flux ropes, which is a part of flux tube dynamo theory and the framework of solar-like magnetic activity. Aims: The aim is to investigate how twisted magnetic flux ropes interact with a simple magnetized stellar model envelope--a magnetic "convection zone"--especially to examine how the twisted magnetic field component of a flux rope interacts with a poloidal magnetic field in the convection zone. Method: Both the flux ropes and the atmosphere are modelled as idealized 2.5-dimensional concepts using high resolution numerical magneto-hydrodynamic (MHD) simulations. Results: It is illustrated that twisted toroidal magnetic flux ropes can interact with a poloidal magnetic field in the atmosphere to cause a change in both the buoyant rise dynamics and the flux rope's geometrical shape. The details of these changes depend primarily on the polarity and strength of the atmospheric field relative to the field strength of the flux rope. It is suggested that the effects could be verified observationally.Comment: 8 pages, 5 figures (9 files), accepted by A&

Doubled haploid ramets via embryogenesis of haploid tissue cultures

Tissue culture in the oil palm business is generally concerned with the multiplication (clonal production) of dura, pisifera and tenera palms. These are all normal diploids (2n=2x=36). Sumatra Bioscience has pioneered haploid tissue culture of oil palm (n=x=18). Haploid oil palm is the first step in producing doubled haploid palms which in turn provide parental lines for F1 hybrid production. Chromosome doubling is known to occur during embryogenesis in other haploid cultures, e.g. barley anther culture. Haploid tissue cultures in oil palm were therefore set up to investigate and exploit spontaneous chromosome doubling during embryogenesis. Flow cytometry of embryogenic tissue showed the presence of both haploid (n) and doubled haploid (2n) cells indicating spontaneous doubling. Completely doubled haploid ramets were regenerated suggesting that doubling occurred during the first mitoses of embryogenesis. This is the first report of doubled haploid production in oil palm via haploid tissue culture. The method provides a means of producing a range of doubled haploids in oil palm from the 1,000 plus haploids available at Sumatra Bioscience, in addition the method also produced doubled haploid (and haploid) clones. 1

La restricción energética en la Argentina de la era del carbón, 1860-1907

The influence of limited access to competitive energy sources on the development of Argentina in the period of national organization is analyzed in this paper. It is the period of coal, power source of the industrial revolution and the basis of England's global dominance, a mineral that Argentina lacks, unlike countries -in other senses analogous- such as Australia and Chile, where coal mining fostered industrialization. British coal imports, a burden on the external balance of the Argentine economy, were fluently integrated into the model and attenuated eventual protectionist measures. Initiatives have been identified showing that local ruling classes were not indifferent to the issue and, both in public and private sectors, aimed at supplying the resource. Despite the efforts, projects failed due to structural deficiencies and adverse geological conditions. When electricity is incorporated as a factor for transforming production, dependence on imported coal increased since the production concentrates in the plains, far from mountain rivers, thus limiting the contribution of hydraulic generation. The first industrial exploitation of oil in the territory, which failed due to the structural limitations of the model, is also studied. Despite the vision and the efforts, Argentina, a country with industrialist aspirations, went through the period as an importer of practically all the energy it needed.Este trabajo analiza la influencia que la dificultad de acceso a fuentes energéticas competitivas tuvo en el desarrollo de Argentina, en el período de la organización nacional. Era el período del carbón, motor de la revolución industrial y base del dominio global de Inglaterra, mineral del que Argentina carecía, a diferencia de países en otros sentidos análogos, como Australia y Chile, donde la explotación impulsó la industrialización. Las importaciones de carbón inglés, una carga sobre el balance externo de la economía argentina, se integraron fluidamente al modelo y atenuaron eventuales medidas proteccionistas. Las clases dirigentes no fueron indiferentes al tema y se han identificado iniciativas, públicas y de particulares, tendientes al abastecimiento del recurso, que fracasaron por carencias estructurales y las condiciones geológicas adversas. Cuando la electricidad se incorporó como factor de transformación de la producción, la dependencia del carbón importado se agravó, porque los núcleos de producción se encontraban alejados de los ríos de montaña, limitando el aporte de la generación hidráulica.  Se estudia también la primera explotación industrial de petróleo en el territorio, que fracasó debido a las limitaciones estructurales características del modelo. A pesar de la visión y de los esfuerzos, Argentina, país de vocación industrialista, atravesó el período como importador de prácticamente la totalidad de la energía que necesitaba

A coupled model of magnetic flux generation and transport in stars

We present a combined model for magnetic field generation and transport in cool stars with outer convection zones. The mean toroidal magnetic field, which is generated by a cyclic thin-layer alpha-omega dynamo at the bottom of the convection zone is taken to determine the emergence probability of magnetic flux tubes in the photosphere. Following the nonlinear rise of the unstable thin flux tubes, emergence latitudes and tilt angles of bipolar magnetic regions are determined. These quantities are put into a surface flux transport model, which simulates the surface evolution of magnetic flux under the effects of large-scale flows and turbulent diffusion. First results are discussed for the case of the Sun and for more rapidly rotating solar-type stars.Comment: Astron. Nachr. /AN, 328, 1111-1113 (2007). A newer, more extended paper related to this study can be reached here: http://arxiv.org/abs/1102.0569 (A&A 528, A135 [2011]). The supplementary animations can be reached here: http://www.aip.de/AN/movie

La restricción energética en la Argentina en la era del carbón: 1860-1907

Fil: Caligari, Rubén Oscar. Universidad de Buenos Aires. Facultad de Ciencias Económicas. Buenos Aires, Argentina

Genetic variation and quantitative trait loci associated with developmental stability and the environmental correlation between traits in maize

11 páginas, 4 figuras, 5 tablas.There is limited experimental information about the genetic basis of micro-environmental variance (VE) (developmental stability) and environmental correlations. This study, by using a population of maize recombinant inbred lines (RIL) and simple sequence repeat (SSR) polymorphic markers, aims at the following: firstly, to quantify the genetic component of the VE or developmental stability for four traits in maize and the environmental correlation between these traits, and secondly, to identify quantitative trait loci (QTLs) that influence these quantities. We found that, when estimating variances and correlations and testing their homogeneity, estimates and tests are needed that are not highly dependent on normality assumptions. There was significant variation among the RILs in VE and in the environmental correlation for some of the traits, implying genetic heterogeneity in the VE and environmental correlations. The genetic coefficient of variation of the environmental variance (GCVVE) was estimated to be 20%, which is lower than estimates obtained for other species. A few genomic regions involved in the stability of one trait or two traits were detected, and these did not have an important influence on the mean of the trait. One region that could be associated with the environmental correlations between traits was also detected.The National Plan for Research and Development of Spain (project code AGL2006-13140) is acknowledged for financial support. B. Ordas acknowledges a contract from the Spanish National Research Council (I3P Program).Peer reviewe

Vardagsmotivationens betydelse för personer med Anorexia Nervosa

The motivation within the psychiatric disease Anorexia Nervosa is often measured with focus on the anorectic’s wish to recover. Even though this motivation is important for a recover from Anorexia Nervosa most studies evaluate this from the single perspective motivation to change. This article is focusing on the relation between motivation and Anorexia Nervosa. An internet survey including 33 questions (30 measuring motivation and 3 measuring Anorexia Nervosa) was formed from the main question about motivation towards everyday life in people suffering from Anorexia Nervosa. The study was directed to young people in the age between 16-24 years old, separated into two groups (Anorectics and Non-anorectics) depending on their answer to the questions about Anorexia Nervosa. The difference between the groups was equivalent, but the Non-Anorectics got a higher result than the Anorectics.Motivation hos anorektiker mäts ofta i samband med förändring, medan andra motivationsområden inte berörs. Genom att bryta ner begreppet i mindre byggstenar syftar denna uppsats till att belysa förhållandet mellan vardagsmotivation och Anorexia Nervosa. Med utgångspunkt i frågeställningen kring anorektikers motivation inför vardagsaktiviteter utformades ett självskattningsformulär bestående av 33 frågor (30 frågor mäter motivation och 3 frågor mäter Anorexia Nervosa) om motivation inför vardagsaktiviteter. Studien riktade sig till unga personer i åldern 16-24 år. Beroende på hur deltagarna skattade sig på frågorna om Anorexia Nervosa delades de in i två grupper (Anorektiker och Icke-Anorektiker). Resultatet var signifikant, men bekräftade inte hypotesen. Vardagsmotivationen var likvärdig hos båda grupperna, men Icke-Anorektiker skattade motivation något högre än Anorektiker

A simple, high throughput method to locate single copy sequences from Bacterial Artificial Chromosome (BAC) libraries using High Resolution Melt analysis

BACKGROUND: The high-throughput anchoring of genetic markers into contigs is required for many ongoing physical mapping projects. Multidimentional BAC pooling strategies for PCR-based screening of large insert libraries is a widely used alternative to high density filter hybridisation of bacterial colonies. To date, concerns over reliability have led most if not all groups engaged in high throughput physical mapping projects to favour BAC DNA isolation prior to amplification by conventional PCR. RESULTS: Here, we report the first combined use of Multiplex Tandem PCR (MT-PCR) and High Resolution Melt (HRM) analysis on bacterial stocks of BAC library superpools as a means of rapidly anchoring markers to BAC colonies and thereby to integrate genetic and physical maps. We exemplify the approach using a BAC library of the model plant Arabidopsis thaliana. Super pools of twenty five 384-well plates and two-dimension matrix pools of the BAC library were prepared for marker screening. The entire procedure only requires around 3 h to anchor one marker. CONCLUSIONS: A pre-amplification step during MT-PCR allows high multiplexing and increases the sensitivity and reliability of subsequent HRM discrimination. This simple gel-free protocol is more reliable, faster and far less costly than conventional PCR screening. The option to screen in parallel 3 genetic markers in one MT-PCR-HRM reaction using templates from directly pooled bacterial stocks of BAC-containing bacteria further reduces time for anchoring markers in physical maps of species with large genomes

3-D non-linear evolution of a magnetic flux tube in a spherical shell: the isentropic case

We present recent 3-D MHD numerical simulations of the non-linear dynamical evolution of magnetic flux tubes in an adiabatically stratified convection zone in spherical geometry, using the anelastic spherical harmonic (ASH) code. We seek to understand the mechanism of emergence of strong toroidal fields from the base of the solar convection zone to the solar surface as active regions. We confirm the results obtained in cartesian geometry that flux tubes that are not twisted split into two counter vortices before reaching the top of the convection zone. Moreover, we find that twisted tubes undergo the poleward-slip instability due to an unbalanced magnetic curvature force which gives the tube a poleward motion both in the non-rotating and in the rotating case. This poleward drift is found to be more pronounced on tubes originally located at high latitudes. Finally, rotation is found to decrease the rise velocity of the flux tubes through the convection zone, especially when the tube is introduced at low latitudes.Comment: 4 pages, 6 ps figure