Formation of X-ray emitting stationary shocks in magnetized protostellar jets

X-ray observations of protostellar jets show evidence of strong shocks heating the plasma up to temperatures of a few million degrees. In some cases, the shocked features appear to be stationary. They are interpreted as shock diamonds. We aim at investigating the physics that guides the formation of X-ray emitting stationary shocks in protostellar jets, the role of the magnetic field in determining the location, stability, and detectability in X-rays of these shocks, and the physical properties of the shocked plasma. We performed a set of 2.5-dimensional magnetohydrodynamic numerical simulations modelling supersonic jets ramming into a magnetized medium and explored different configurations of the magnetic field. The model takes into account the most relevant physical effects, namely thermal conduction and radiative losses. We compared the model results with observations, via the emission measure and the X-ray luminosity synthesized from the simulations. Our model explains the formation of X-ray emitting stationary shocks in a natural way. The magnetic field collimates the plasma at the base of the jet and forms there a magnetic nozzle. After an initial transient, the nozzle leads to the formation of a shock diamond at its exit which is stationary over the time covered by the simulations (~ 40 - 60 yr; comparable with time scales of the observations). The shock generates a point-like X-ray source located close to the base of the jet with luminosity comparable with that inferred from X-ray observations of protostellar jets. For the range of parameters explored, the evolution of the post-shock plasma is dominated by the radiative cooling, whereas the thermal conduction slightly affects the structure of the shock.Comment: Accepted for publication in Astronomy and Astrophysic

La primera década del conflicto en defensa de la Autonomía Local

First decade of constitutional conflict in defense of local autonomy has not demonstrated its success in order to promote local Governments powers. This paper analyzes the causes of that and it promotes to seek solutions to local government problems beyond the Constitutional Court. Challenges facing local autonomy in Spain, as local Governments’ adequate structure, financial coverage of local powers and the correction of democratic rules at local institutions are examined here.El examen de la práctica del conflicto en defensa de la autonomía local en en su primera década de funcionamiento refleja una escasa eficacia del mismo como medio para incrementar los poderes del gobierno local español. El trabajo examina las razones de esta escasa eficacia práctica y aboga por buscar, más allá de los remedios procesales, las soluciones a los retos que enfrenta el mundo local, como la dimensión y estructura organizativa del nivel local de gobierno, la financiación de las entidades locales y el funcionamiento de las instituciones locales desde el punto de vista del buen gobierno democrático

Especialización vertical, outsourcing e inversión directa en la industria española

No se puede entender la globalización sin estudiar la creciente expansión del comercio internacional de bienes intermedios. Las medidas de outsourcing aquí utilizadas a partir de la tablas input-output permiten explicar la evolución del comercio intra-industrial e inter-industrial de la industria española entre 1995 y 2000. La especialización vertical permite avanzar un poco más, al vincular las importaciones de inputs que requiere un país con las exportaciones que éste realiza. Además, se analiza el papel que han jugado tanto la presencia de multinacionales extranjeras como los flujos de entrada y de salida de inversiones directas en el outsourcing. Los resultados indican que en las ramas de alta tecnología la presencia de multinacionales va asociada a un alto outsourcing intra-industrial y que en algunas ramas tradicionales el outsourcing va acompañado de inversiones españolas en el exterior. ____________________________________________ It is not possible to understand the globalisation process without studying the growing expansion of international trade in intermediate goods. The outsourcing measures used in this paper are calculated from input-output tables and allow us to explain the evolution of intra –and inter– industrial trade for the Spanish manufactures in 1995-2000. Vertical specialization goes a step further by linking imports of inputs required by a country and its exports. Furthermore, this paper analyses the impact on outsourcing of both the presence of multinational firms (MNEs) and the inward and outward flows of direct investment. Our results indicate that in high-tech sectors, the presence of MNEs is linked to high intra-industrial outsourcing, and in some traditional (low-tech) outsourcing is related to Spanish outward FDI

Optimizing tip-surface interactions in ESR-STM experiments

Electron-spin resonance carried out with scanning tunneling microscopes (ESR-STM) is a recently developed experimental technique that is attracting enormous interest on account of its potential to carry out single-spin on-surface resonance with subatomic resolution. Here we carry out a theoretical study of the role of tip-adatom interactions and provide guidelines for choosing the experimental parameters in order to optimize spin resonance measurements. We consider the case of the Fe adatom on a MgO surface and its interaction with the spin-polarized STM tip. We address three problems: first, how to optimize the tip-sample distance to cancel the effective magnetic field created by the tip on the surface spin, in order to carry out proper magnetic field sensing. Second, how to reduce the voltage dependence of the surface-spin resonant frequency, in order to minimize tip-induced decoherence due to voltage noise. Third, we propose an experimental protocol to infer the detuning angle between the applied field and the tip magnetization, which plays a crucial role in the modeling of the experimental results.Comment: 10 pages, 5 Figure

XMM-Newton monitoring of the close pre-main-sequence binary AK Sco. Evidence of tide-driven filling of the inner gap in the circumbinary disk

AK Sco stands out among pre-main-sequence binaries because of its prominent ultraviolet excess, the high eccentricity of its orbit, and the strong tides driven by it. AK Sco consists of two F5-type stars that get as close as 11 R-* at periastron passage. The presence of a dense (n(e) similar to 10(11) cm(-3)) extended envelope has been unveiled recently. In this article, we report the results from an XMM-Newton-based monitoring of the system. We show that at periastron, X-ray and UV fluxes are enhanced by a factor of similar to 3 with respect to the apastron values. The X-ray radiation is produced in an optically thin plasma with T similar to 6.4 x 10(6) K and it is found that the N-H column density rises from 0.35 x 10(21) cm(-2) at periastron to 1.11 x 10(21) cm(-2) at apastron, in good agreement with previous polarimetric observations. The UV emission detected in the Optical Monitor band seems to be caused by the reprocessing of the high-energy magnetospheric radiation on the circumstellar material. Further evidence of the strong magnetospheric disturbances is provided by the detection of line broadening of 278.7 km s(-1) in the Nv line with Hubble Space Telescope/Space Telescope Imaging Spectrograph. Numerical simulations of the mass flow from the circumbinary disk to the components have been carried out. They provide a consistent scenario with which to interpret AK Sco observations. We show that the eccentric orbit acts like a gravitational piston. At apastron, matter is dragged efficiently from the inner disk border, filling the inner gap and producing accretion streams that end as ring-like structures around each component of the system. At periastron, the ring-like structures come into contact, leading to angular momentum loss, and thus producing an accretion outburst

Reduced Graphene Oxides as Carbocatalysts in Acceptorless Dehydrogenation of N-Heterocycles

[EN] The catalytic properties of graphene-derived materials are evaluated in acceptorless dehydrogenation of N-heterocycles. Among them, reduced graphene oxides (rGOs) are active (quantitative yields in 23 h) under mild conditions (130 degrees C) and act as efficient heterogeneous carbocatalysts. rGO exhibits reusability and stability at least during eight consecutive runs. Mechanistic investigations supported by experimental evidence (i.e., organic molecules as model compounds, purposely addition of metal impurities and selective functional group masking experiments) suggest a preferential contribution of ketone carbonyl groups as active sites for this transformation.Supported by MCIN/AEI/10.13039/501100011033/FEDER (Grant Nos. RTI2018-098237-B-C21, RTI2018-098237-BC22, and PID2019-105881RB-I00), Generalitat Valenciana (No. PROMETEU/2020/028), and Universitat Jaume I (No. UJI-B2018-23).Mollar-Cuni, A.; Ventura-Espinosa, D.; Martin, S.; García Gómez, H.; Mata, JA. (2021). Reduced Graphene Oxides as Carbocatalysts in Acceptorless Dehydrogenation of N-Heterocycles. ACS Catalysis. 11(23):1-6. https://doi.org/10.1021/acscatal.1c04649S16112

Basic walking and running patterns in 5 to 8 Year old girls by nonlinear feature extraction

Fueron caracterizados los patrones básicos de movimien-to caminar y correr, en niñas de 5 a 8 años, residentes en áreas urbanas, mediante extracción no lineal de característi-cas. Se evaluaron 48 niñas, entre 5,7 y 8,9 años de edad (X 7,05±0,99 años), de un colegio privado de Manizales-Cal-das, Colombia. Se emplearon técnicas de reconocimiento automatizado de patrones para obtener información acerca de posibles deficiencias motoras, fortalecer la detección temprana de falencias o deterioro biomecánico. La captura de imagen fue hecha con ocho cámaras de rayos infrarrojos que, mediante el programa OptiTrack Arena versión 1.7.0, permitieron formar esquemas de postura y posteriormente evaluados por expertos. Un consentimiento informado fue firmado por padres o acudientes. Las evaluadas, se despla-zaron a velocidad submáxima autoelegida. Para propósitos de familiarización con la prueba, las participantes completa-ron dos intentos de práctica caminando o corriendo. Se en-contró que un 57,14% presentó anormalidades en el patrón de caminar y un 46,94%, en el de correr. Frente a lo esperado para la edad, se concluyó que un 56,12% de las niñas eva-luadas presenta patrones inmaduros para su edad, por lo que se recomienda incluir estos temas, con las respectivas correcciones, en los procesos de desarrollo motor.Basic movement patterns, walking and jogging, were characterized in girls 5 to 8 years old living in urban areas, using non-linear features extraction. 48 girls were evaluated, aged between 5.7 to 8.9 years (mean 7.05±0.99 years) from a private school on Manizales, Caldas, Colombia. Automated pattern recognition techniques were used to obtain information about possible motor deficiencies, strengthen early detection of flaws or biomechanical deterioration. Image capture was done with eight infrared cameras allowing through Arena OptiTrack version 1.7.0 form posture schemes, later assessed by experts. Informed consent was signed by parents or guardians. The evaluated individuals moved at submaximal auto elected speed. For the purpose of familiarization with the test, the participants completed two attempts to practice walking or running. It was found that a 57.14% had abnormalities in the walking pattern and a 46.94% in the running one. Faced with the expectancy for age, it was concluded that a 56.12% of the evaluated girls showed immature patterns for their age; therefore it is recommended to include these issues with the respective corrections in motor development processes.Incluye referencias bibliográfica