Orbits and masses in the young triple system TWA 5

We aim to improve the orbital elements and determine the individual masses of the components in the triple system TWA 5. Five new relative astrometric positions in the H band were recorded with the adaptive optics system at the Very Large Telescope (VLT). We combine them with data from the literature and a measurement in the Ks band. We derive an improved fit for the orbit of TWA 5Aa-b around each other. Furthermore, we use the third component, TWA 5B, as an astrometric reference to determine the motion of Aa and Ab around their center of mass and compute their mass ratio. We find an orbital period of 6.03+/-0.01 years and a semi-major axis of 63.7+/-0.2 mas (3.2+/-0.1 AU). With the trigonometric distance of 50.1+/-1.8 pc, this yields a system mass of 0.9+/-0.1 Msun, where the error is dominated by the error of the distance. The dynamical mass agrees with the system mass predicted by a number of theoretical models if we assume that TWA5 is at the young end of the age range of the TW Hydrae association. We find a mass ratio of M_Ab / M_Aa = 1.3 +0.6/-0.4, where the less luminous component Ab is more massive. This result is likely to be a consequence of the large uncertainties due to the limited orbital coverage of the observations.Comment: 9 pages, 8 figures, accepted by Astronomy and Astrophysic

Multiple energetic injections in a strong spike-like solar burst

An intense and fast spike-like solar burst was built up of short time scale structures superimposed on an underlying gradual emission, the time evolution of which shows remarkable proportionality between hard X-ray and microwave fluxes. The finer time structure were best defined at mm-microwaves. At the peak of the event, the finer structures repeat every 30x60ms. The more slowly varying component with a time scale of about 1 second was identified in microwave hard X-rays throughout the burst duration. It is suggested that X-ray fluxes might also be proportional to the repetition rate of basic units of energy injection (quasi-quantized). The relevant parameters of one primary energy release site are estimated both in the case where hard X-rays are produced primarily by thick-target bremsstrahlung, and when they are purely thermal. The relation of this figure to global energy considerations is discussed

Valores, actitudes y comportamientos sociopolíticos de los estudiantes portugueses de economía

Previous research on the Portuguese case confirmed free-riding, free-marketer and right-wing political inclinations among economics students. Further scrutiny was endeavored here, perceiving also a considerably increased interest for politics, notwithstanding the lack of concern for public problems. Various aspects of free-riding proclivity were distinguished and discussed, relating them with youngsters’ risk-loving and sensation-seeking tendencies, but also with a number of other facets specific to economics students, including: prevalence of achievement values, contextual influences on morals, peer pressure, perceived group status and social expectations regarding the economic profession.Pesquisas anteriores sobre o caso português confirmaram inclinações políticas de direita e pró-mercado entre os estudantes de economia, a par duma maior tendência para o free-riding. Investigação subsequente, ora exposta, permitiu perceber também uma atração acrescida pela política, não obstante a falta de interesse pelos problemas públicos. Diversos aspetos da inclinação free-rider foram distinguidos, relacionando-os com propensão juvenil para o risco e a busca de sensações, mas também com traços específicos dos estudantes de economia, incluindo: prevalência de valores de realização, influências contextuais na moralidade, pressão dos pares, perceção de status e expetativas associadas à profissão de economista.Des études antérieures ont confirmé la prévalence de tendances politiques de droite et pro-marché parmi les étudiants d’économie au Portugal, parallèlement à une inclination accrue pour le free-riding. Des recherches subséquentes, ici exposés, ont détecté aussi une intense attraction par la politique, malgré l’indifférence vers la vie publique. Plusieurs aspects de la pente vers le free-riding ont été distingués, en les rapportant à la propension des jeunes pour le risque et la recherche de sensations, mais également à des traits spécifiques des étudiants d’économie, nommément: valeurs d’accomplissement, influences contextuelles sur la moralité, pression des pairs, perception de statut et attentes relatives à la profession d’économiste.Pesquisas anteriores en el caso portugués confirmaron inclinaciones políticas de derecha y pro-mercado entre los estudiantes de economía, en paralelo con una mayor tendencia al free-riding. Investigación subsiguiente, aquí expuesta, permitió percibir también una mayor atracción por la política, pero sin interés por asuntos públicos. Diversos aspectos de la inclinación free-rider fueron distinguidos, relacionándolos con la propensión juvenil hacia el riesgo y la búsqueda de sensaciones, pero también con aspectos específicos de los estudiantes de economía: prevalencia de valores de realización, influencias contextuales en la moralidad, presión de los pares, percepción de status y expectativas relativas a la profesión de economista

Dynamic capabilities: Antecedents and implications for firms' performance

Purpose: This paper aims to explore a new causal link between learning, market and entrepreneurial orientations and firms' performance by introducing dynamic capabilities and competitive advantages as mediator variables. Design/methodology/approach: The mediating role of dynamic capabilities and competitive advantages is tested using a sample of 1,190 Portuguese firms, and structural equation models. Findings: It is shown that dynamic capabilities mediate the relationship between the three orientations–learning, market and entrepreneurial–and competitive advantages of differentiation and cost leadership, and both competitive advantages lead to firm's performance. It is also shown that learning orientation is an antecedent of market orientation and entrepreneurial orientation. Practical implications: This research shows that firm's performance depends on the capacity of firms to learn, innovate, be proactive, take risks and collect the best market data. Indeed, by optimizing the internal management and knowledge dissemination, firms will develop a set of capabilities and competitive advantages that lead to an appropriate response to market challenges. Originality/value: This study tests the relationship between strategic orientations and firm's performance by taking the mediating effects of dynamic capabilities and competitive advantages into account. This research was conducted in Portugal.info:eu-repo/semantics/acceptedVersio

Stellar and circumstellar properties of visual binaries in the Orion Nebula Cluster

Our general understanding of multiple star and planet formation is primarily based on observations of young multiple systems in low density regions like Tau-Aur and Oph. Since many, if not most, of the stars are born in clusters, observational constraints from young binaries in those environments are fundamental for understanding both the formation of multiple systems and planets in multiple systems throughout the Galaxy. We build upon the largest survey for young binaries in the Orion Nebula Cluster (ONC) which is based on Hubble Space Telescope observations to derive both stellar and circumstellar properties of newborn binary systems in this cluster environment. We present Adaptive Optics spatially-resolved JHKL'-band photometry and K-band R$\sim$\,5000 spectra for a sample of 8 ONC binary systems from this database. We characterize the stellar properties of binary components and obtain a census of protoplanetary disks through K-L' color excess. For a combined sample of ONC binaries including 7 additional systems with NIR spectroscopy from the literature, we derive mass ratio and relative age distributions. We compare the stellar and circumstellar properties of binaries in ONC with those in Tau-Aur and Oph from samples of binaries with stellar properties derived for each component from spectra and/or visual photometry and with a disk census obtained through K-L color excess. The mass ratio distribution of ONC binaries is found to be indistinguishable from that of Tau-Aur and, to some extent, to that of Oph in the separation range 85-560\,AU and for primary mass in the range 0.15 to 0.8\,M_{\sun}.A trend toward a lower mass ratio with larger separation is suggested in ONC binaries which is not seen in Tau-Aur binaries.The components of ONC binaries are found to be significantly more coeval than the overall ONC population and as coeval as components of binaries in Tau-Aur and Oph[...]Comment: Accepted for publication in Astronomy & Astrophysic

Single-chip CMOS optical microspectrometer

Numerous applications, e.g., systems for chemical analysis by optical absorption and emission line characterization, will benefit from the availability of low-cost single-chip spectrometers. A single-chip CMOS optical microspectrometer containing an array of 16 addressable Fabry–Perot etalons (each one with different resonance cavity length), photodetectors and circuits for read-out, multiplexing and driving a serial bus interface has been fabricated. The result is a chip that can operate using only four external connections (including Vdd and Vss). covering the visible spectral range of the spectrum with FWHM = 18 nm. Frequency output and serial bus interface allow easy multi-sensor, multi-chip interfacing using a microcontroller or a personal computer. Power consumption is 1250 µW for a clock frequency of 1 MHzFundação para a Ciência e a Tecnologia (FCT

Subsídios para uma estratégia emergencial de redução dos efeitos da seca na pecuária no Semi-Árido brasileiro.

As secas constituem um fenômeno recorrente na região semi-árida brasileira e, portanto, deveriam ser consideradas pelos pecuaristas como um entre os muitos fatores de produção. Tal, contudo, não acontece e os prejuízos causados por períodos prolongados de seca são sempre acentuados. Pesquisadores da Embrapa Semi-Árido, em Petrolina, PE, propõem uma estratégia para reduzir expressivamente esses prejuízos, nos casos em que os produtores não contam com suficientes pastos nem forragem estocada para enfrentar uma estiagem prolongada que se prenuncia. Ela se baseia no enfoque de preservação de um capital mínimo e no estabelecimento de medidas institucionais, a serem conduzidas por comissões técnicas, de nível municipal ou micro-regional, e de medidas de caráter individual, a serem adotadas pelos pecuaristas, ao nível de Propriedade. O trabalho apresenta as principais ações a serem desenvolvidas pelas comissões e pelos produtores para conviver emergencialmente com as secas, caracterizando as vantagens potenciais de sua adoçã

Analysis of cosmic ray variations observed by the CARPET in association with solar flares in 2011-2012

The CARPET cosmic ray detector was installed on April 2006 at CASLEO (Complejo Astronmico El Leoncito) at the Argentinean Andes (31.8S, 69.3W, 2550 m, Rc=9.65 GV). This instrument was developed within an international cooperation between the Lebedev Physical Institute RAS (LPI; Russia), the Centro de Radio Astronomia e Astrofsica Mackenzie (CRAAM; Brazil) and the Complejo Astronmico el Leoncito (CASLEO; Argentina). In this paper we present results of analysis of cosmic ray variations recorded by the CARPET during increased solar flare activity in 2011-2012. Available solar and interplanetary medium observational data obtained onboard GOES, FERMI, ISS, as well as cosmic ray measurements by ground-based neutron monitor network were also used in the present analysis.Fil: Makhmutov, V.. Lebedev Physical Institute; Rusia. Universidade Presbiteriana Mackenzie; BrasilFil: Raulin, J. P.. Universidade Presbiteriana Mackenzie; BrasilFil: De Mendonca, R. R. S.. National Institute for Space Research; BrasilFil: Bazilevskaya, G. A.. Lebedev Physical Institute; RusiaFil: Correia, E.. Universidade Presbiteriana Mackenzie; Brasil. National Institute for Space Research; BrasilFil: Kaufmann, Pierre. Universidade Presbiteriana Mackenzie; BrasilFil: Marun, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Fernandez, German Enzo Leonel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Echer, E.. National Institute for Space Research; Brasi