Accelerating AGN jets to parsec scales using general relativistic MHD simulations

Accreting black holes produce collimated outflows, or jets, that traverse many orders of magnitude in distance, accelerate to relativistic velocities, and collimate into tight opening angles. Of these, perhaps the least understood is jet collimation due to the interaction with the ambient medium. In order to investigate this interaction, we carried out axisymmetric general relativistic magnetohydrodynamic simulations of jets produced by a large accretion disc, spanning over 5 orders of magnitude in time and distance, at an unprecedented resolution. Supported by such a disc, the jet attains a parabolic shape, similar to the M87 galaxy jet, and the product of the Lorentz factor and the jet half-opening angle, $\gamma\theta\ll 1$, similar to values found from very long baseline interferometry (VLBI) observations of active galactic nuclei (AGN) jets; this suggests extended discs in AGN. We find that the interaction between the jet and the ambient medium leads to the development of pinch instabilities, which produce significant radial and lateral variability across the jet by converting magnetic and kinetic energy into heat. Thus pinched regions in the jet can be detectable as radiating hotspots and may provide an ideal site for particle acceleration. Pinching also causes gas from the ambient medium to become squeezed between magnetic field lines in the jet, leading to enhanced mass-loading of the jet and potentially contributing to the spine-sheath structure observed in AGN outflows.Comment: 18 pages, 24 figures, submitted to MNRAS, revised version. See our Youtube channel for accompanying animations: https://www.youtube.com/playlist?list=PLjldVlE2vDFzHMGn75tgc2Lod0kcTWZd

Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

Using Suzaku and the Rossi X-ray Timing Explorer, we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard low states. Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the focused wind from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating. These latter spectra are crucial for revealing the ionized absorption due to the secondary's focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c^2. All three models also agree that the known spectral break at 10\,keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, {thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is >40 GM/c^2.Comment: 22 pages, 16 figures. Uses emulateapj style. Final three tables inserted as a figure to avoid issues with astro-ph's version of latex mangling the use of lscape. To be published in the Astrophysical Journal, January, 201

Thermodynamical Study on the Heavy-Fermion Superconductor PrOs4Sb12: Evidence for Field-Induced Phase Transition

We report measurements of low-temperature specific heat on the 4f^2-based heavy-fermion superconductor PrOs4Sb12. In magnetic fields above 4.5 T in the normal state, distinct anomalies are found which demonstrate the existence of a field-induced ordered phase (FIOP). The Pr nuclear specific heat indicates an enhancement of the 4f magnetic moment in the FIOP. Utilizing a Maxwell relation, we conclude that anomalous entropy, which is expected for a single-site quadrupole Kondo model, is not concealed below 0.16 K in zero field. We also discuss two possible interpretations of the Schottky-like anomaly at ~3 K, i.e., a crystalline-field excitation or a hybridization gap formation.Comment: 5 pages with 5 figures, a note with two references added in proo

Identificação de polimorfismos em genótipos de Coffea arabica de uma coleção da Etiópia.

Os marcadores moleculares são ferramentas importantes para acelerar os programas de melhoramento. Para o cafeeiro, uma espécie perene, o uso de marcadores é particularmente desejável devido ao tempo e recursos gastos para o lançamento de uma nova cultivar. Duas espécies do gênero Coffea são responsáveis por quase toda a produção de café: Coffea arabica e C. canephora. Contudo, para C. arabica, o número de marcadores polimórficos é relativamente baixo comparado a C. canephora e outras culturas, uma vez que a espécie apresenta baixa diversidade genética. Muitos estudos com marcadores genéticos foram feitos para analisar a diversidade da C. arabica, mas os resultados não foram eficientes para a discriminação genotípica detalhada e mapeamento genético. O Instituto Agronômico do Paraná (IAPAR) possui uma coleção de 132 acessos de C. arabica originários da Etiópia, que apresentam variabilidade fenotípica com potencial para serem utilizados para exploração da diversidade. Neste sentido, este estudo buscou analisar a diversidade nucleotídica pela identificação de polimorfismos, SNPs e INDELs, de uma população do centro de origem de C. arabica, associado com o sequenciamento de nova geração. O RNA-seq de dois tecidos, frutos e folhas, de quatro genótipos de C. arabica de uma população da Etiópia, C. arabica cv. Mundo Novo e de um dos seus ancestrais de C. arabica ? C. eugenioides, foram sequenciados pela metodologia Illumina HiSeq2000. Os reads obtidos foram processados e posteriormente as sequências foram mapeadas em uma referência de C. canephora para identificação dos polimorfismos. Foram feitas duas estratégias: i) na primeira estratégia, foi utilizado uma ferramenta chamada SNiPloid com critérios de cobertura para o polimorfismo identificado e ii) uma segunda estratégia que considera os polimorfismos encontrados diretamente dos arquivos de detecção dos polimorfismos. Os resultados identificaram um número grande de polimorfismos. Na primeira estratégia, foram encontrados pelo menos 5.500 SNPs potenciais para a genotipagem e na segunda, 103.791 SNPs potenciais. Para essa última, ainda é necessário estabelecer critérios e filtros para escolher os polimorfismos que serão inicialmente genotipados. Os dados também mostraram a importância de utilizar um grupo mais diverso de genótipos associado com o sequenciamento de nova geração para detecção de SNPs. Este trabalho será importante para direcionar futuros trabalhos na caracterização da diversidade genética em C. arabica, além de estudos de mapeamento genético por associação

Multi-layer adaptation of group coordination in musical ensembles

Group coordination passes through an efficient integration of multimodal sources of information. This study examines complex non-verbal communication by recording movement kinematics from conductors and two sections of violinists of an orchestra adapting to a perturbation affecting their normal pattern of sensorimotor communication (rotation of half a turn of the first violinists’ section). We show that different coordination signals are channeled through ancillary (head kinematics) and instrumental movements (bow kinematics). Each one of them affect coordination either at the inter-group or intra-group levels, therefore tapping into different modes of cooperation: complementary versus imitative coordination. Our study suggests that the co-regulation of group behavior is based on the exchange of information across several layers, each one of them tuned to carry specific coordinative signals. Multi-layer sensorimotor communication may be the key musicians and, more generally humans, use to flexibly communicate between each other in interactive sensorimotor tasks

Analysis of Diterpens in Green and Roasted Coffee of Coffea arabica Cultivars Growing in the Same Edapho-Climatic Conditions.

Lipids are important components of coffee beverage flavor and aroma. Coffee oil is rich in diterpens of the kaurane family, mainly cafestol (C20H28O3) and kahweol (C20H26O3), which have increasingly received attention in recent years due to their physiological effects in human health. However, few studies have been conducted on the effects of the genetic variability for those lipids in Coffea arabica. In this work we initiate the characterization of cafestol and kahweol in different cultivars of Coffea arabica, growing in the same edaphoclimatic conditions. Mature coffee fruits from cultivars Catuaí, Icatu and three Catucaí derived the cultivars IPR 100, IPR 102 and IPR 106. They were harvested at the Agricultural Field Station of the Coop COCARI, Mandaguari, Paraná, Brazil, from May to July 2009. Although the time of harvesting was according to the maturation of each cultivar, harvesting and post-harvesting conditions were the same for all cultivars. The five samples were subjected to medium roasting for 8 to 11 minutes at 200-210 °C, until the degree of roasting light/media (L* around 28). The extraction of diterpens was carried out in green or roasted coffee by direct saponification with KOH, extraction with terc-butyl methyl ether, and clean up with water. A reverse-phase HPLC column with isocratic elution with acetonitrile/water (55/45 v/v) was used for detection and quantification of kahweol at 290 nm and cafestol at 220 nm. In green beans, the level of kahweol was higher than cafestol, for all three IPR cultivars. Meanwhile, the inverse was observed for green beans cultivars Catuaí and Icatu, where cafestol levels were higher than kahweol. The higher levels of kahweol in relation to cafestol were again observed in roasted coffee of the three IPR cultivars. In cultivars Icatu the values for kahweol and cafestol were similar (635 and 683 mg/100 g, respectively). The highest levels of kahweol were observed in cultivar IPR 106 (1096 mg/100 g). The cultivar IPR 102 showed the highest level of cafestol (394 mg/100g). Association of this data with gene expression profile can be useful to find genes involved in cafestol and kahweol metabolism as well as to develop molecular markers for diterpens in coffee

Going with the flow: can the base of jets subsume the role of compact accretion disk coronae?

The hard state of X-ray binaries (XRBs) is characterized by a power law spectrum in the X-ray band, and a flat/inverted radio/IR spectrum associated with occasionally imaged compact jets. It has generally been thought that the hard X-rays result from Compton upscattering of thermal accretion disk photons by a hot, coronal plasma whose properties are inferred via spectral fitting. Interestingly, these properties-especially those from certain magnetized corona models-are very similar to the derived plasma conditions at the jet footpoints. Here we explore the question of whether the `corona' and `jet base' are in fact related, starting by testing the strongest premise that they are synonymous. In such models, the radio through the soft X-rays are dominated by synchrotron emission, while the hard X-rays are dominated by inverse Compton at the jet base - with both disk and synchrotron photons acting as seed photons. The conditions at the jet base fix the conditions along the rest of the jet, thus creating a direct link between the X-ray and radio emission. We also add to this model a simple iron line and convolve the spectrum with neutral reflection. After forward-folding the predicted spectra through the detector response functions, we compare the results to simultaneous radio/X-ray data obtained from the hard states of the Galactic XRBs GX339-4 and Cygnus X-1. Results from simple Compton corona model fits are also presented for comparison. We demonstrate that the jet model fits are statistically as good as the single-component corona model X-ray fits, yet are also able to address the simultaneous radio data.Comment: Accepted to the Astrophysical Journal. 14 pages, emulateapj.st

An extended mixed-effects framework for meta-analysis

Standard methods for meta‐analysis are limited to pooling tasks in which a single effect size is estimated from a set of independent studies. However, this setting can be too restrictive for modern meta‐analytical applications. In this contribution, we illustrate a general framework for meta‐analysis based on linear mixed‐effects models, where potentially complex patterns of effect sizes are modeled through an extended and flexible structure of fixed and random terms. This definition includes, as special cases, a variety of meta‐analytical models that have been separately proposed in the literature, such as multivariate, network, multilevel, dose‐response, and longitudinal meta‐analysis and meta‐regression. The availability of a unified framework for meta‐analysis, complemented with the implementation in a freely available and fully documented software, will provide researchers with a flexible tool for addressing nonstandard pooling problems

Detection of Potential Induced Degradation in c-Si PV Panels Using Electrical Impedance Spectroscopy

Impedance spectroscopy (IS) is an established characterization and diagnostic method for different electrical and chemical research areas such as batteries and fuel cells, but not yet widely adopted for photovoltaics (PV). This work, for the first time, investigates an IS based method for detecting potential-induced degradation (PID) in c-Si PV panels. The method has been experimentally tested on a set of panels that were confirmed to be affected by PID by using traditional current-voltage (I-V) characterization methods, as well as electroluminescence (EL) imaging. The results confirm the effectiveness of the new approach to identify PID in PV panels.</p