Recent activity of the Be/X-ray binary system SAX J2103.5+4545

Aims. We present a multiwavelength study of the Be/X-ray binary system SAX J2103.5+4545 with the goal of better characterizing the transient behaviour of this source. Methods. SAX J2103.5+4545 was observed by Swift-XRT four times in 2007 from April 25 to May 5, and during quiescence in 2012 August 31. In addition, this source has been monitored from the ground-based astronomical observatories of El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain) and Sierra Nevada (Granada, Spain) since 2011 August, and from the TUBITAK National Observatory (Antalya, Turkey) since 2009 June. We have performed spectral and photometric temporal analyses in order to investigate the different states exhibited by SAX J2103.5+4545. Results. In X-rays, an absorbed power law model provided the best fit for all the XRT spectra. An iron-line feature at ~6.42 keV was present in all the observations except for that taken during quiescence in 2012. The photon indexes are consistent with previous studies of SAX J2103.5+4545 in high/low luminosity states. Pulsations were found in all the XRT data from 2007 (2.839(2) mHz; MJD 54222.02), but not during quiescence. Both optical outbursts in 2010 and 2012 lasted for about 8/9 months (as the one in 2007 probably did and the current one in 2014 might do) and were most probably caused by mass ejection events from the Be star that eventually fed the circumstellar disc. All of these outbursts started about 3 months before the triggering of the X-ray activity, and about the same period before the maximum of the H_alpha line equivalent width (in emission) was reached at only ~ -5 \AA. In this work we found that the global correlation between the BV variability and the X-ray intensity was also observed at longer wavelengths in the IR domain.Comment: 11 pages, 7 figures, and online material (2 tables). Submitted to A&A in 2014 Januar

The individual’s perception of institutional environments and entrepreneurial motivation in developing economies: Evidence from Cape Verde

Background: International organisations and national governments have made great efforts to stimulate entrepreneurial activity in the less-advanced economies, but the results of their programmes have often been disappointing. This may be because a distinction between the institutional factors that generate an individual’s desire to become an entrepreneur and those that generate a motivation that actually leads to entrepreneurial action has not been considered sufficiently. Aim: This work is an attempt to respond to the following question on the basis of the individual’s perception of regulative, normative and cognitive institutions: In developing economies, what institutional factors generate an entrepreneurial motivation that makes individuals desire to become entrepreneurs and what factors cause an entrepreneurial motivation that actually leads them to entrepreneurial action? Setting: We use empirical evidence from the African nation of Cape Verde for the analysis. The study was carried out on 6 of the 10 islands of the archipelago. Method: The sample of study comprises 237 people: 93 entrepreneurs and 144 individuals with different levels of desire to become an entrepreneur. We used multiple linear regression analysis to test the hypotheses. Results: Our findings show that institutional factors which generate the entrepreneurial motivation that forges an individual’s desire to become an entrepreneur, and those which generate the motivation that leads him or her to actually set up his or her own business are not the same. We also find differences in the institutional factors that influence the opportunity, necessity and social components of entrepreneurial motivation. Conclusion: Theoretical implications for better understanding the factors that condition entrepreneurship in developing economies and practical implications useful for improving the planning of growth in these countries are offered

PROBLEMÁTICA DE LA APLICACIÓN DE AGUA MARINA DESALINIZADA AL RIEGO AGRÍCOLA. CASO DE ESTUDIO DEL CANAL DEL CAMPO DE CARTAGENA

[ES] En este trabajo se presenta una revisión de las principales cuestiones agronómicas y de manejo que se deben considerar cuando se plantea la incorporación de agua marina desalinizada en el riego agrícola. Este análisis se fundamenta en una revisión bibliográfica a escala internacional de las primeras experiencias que se están dando a conocer mediante publicaciones en el ámbito científico. Los principales aspectos a considerar en el riego con agua marina desalinizada son: (1) carencias y desequilibrios nutricionales en la composición química, que pueden limitar el desarrollo de los cultivos; (2) elevada concentración de boro, que puede producir problemas de fitotoxicidad en cultivos sensibles; (3) elevada acidez y poder corrosivo como consecuencia de la escasa mineralización del agua, que puede afectar a las instalaciones de riego; y (4) necesidad de una mayor capacidad de control y gestión del agua en las explotaciones agrícolas. Además, se analiza la problemática en un caso de estudio concreto, que se corresponde con la incorporación de agua marina desalinizada al embalse de La Pedrera, analizándose la mitigación de sus posibles inconvenientes mediante la mezcla en distintas proporciones con el agua continental suministrada habitualmente a dicho embalse mediante las infraestructuras del postrasvase Tajo-Segura.Martínez-Alvarez, V.; Martin-Gorriz, B.; Soto-Garcia, M. (2015). PROBLEMÁTICA DE LA APLICACIÓN DE AGUA MARINA DESALINIZADA AL RIEGO AGRÍCOLA. CASO DE ESTUDIO DEL CANAL DEL CAMPO DE CARTAGENA. En XXXIII CONGRESO NACIONAL DE RIEGOS. Valencia 16-18 junio de 2015. Editorial Universitat Politècnica de València. https://doi.org/10.4995/CNRiegos.2015.1438OC

Instantons and <A2><A^2> Condensate

We argue that the $$condensate found in the Landau gauge on lattices, when an Operator Product Expansion of Green functions is performed, might be explained by instantons. We use cooling to estimate the instanton contribution and extrapolate back the result to the thermalised configuration. The resulting$$ is similar to $$.Comment: 6 pages, 1 fig., 1 tab., RevTeX to be use

The evolution of Balmer jump selected galaxies in the ALHAMBRA survey

We present a new color-selection technique, based on the Bruzual & Charlot models convolved with the bands of the ALHAMBRA survey, and the redshifted position of the Balmer jump to select star-forming galaxies in the redshift range 0.5 < z < 1.5. These galaxies are dubbed Balmer jump Galaxies BJGs. We apply the iSEDfit Bayesian approach to fit each detailed SED and determine star-formation rate (SFR), stellar mass, age and absolute magnitudes. The mass of the haloes where these samples reside are found via a clustering analysis. Five volume-limited BJG sub-samples with different mean redshifts are found to reside in haloes of median masses $\sim 10^{12.5 \pm 0.2} M_\odot$ slightly increasing toward z=0.5. This increment is similar to numerical simulations results which suggests that we are tracing the evolution of an evolving population of haloes as they grow to reach a mass of $\sim 10^{12.7 \pm 0.1} M_\odot$ at z=0.5. The likely progenitors of our samples at z$\sim$3 are Lyman Break Galaxies, which at z$\sim$2 would evolve into star-forming BzK galaxies, and their descendants in the local Universe are elliptical galaxies.Hence, this allows us to follow the putative evolution of the SFR, stellar mass and age of these galaxies. From z$\sim$1.0 to z$\sim$0.5, the stellar mass of the volume limited BJG samples nearly does not change with redshift, suggesting that major mergers play a minor role on the evolution of these galaxies. The SFR evolution accounts for the small variations of stellar mass, suggesting that star formation and possible minor mergers are the main channels of mass assembly.Comment: 14 pages, 10 figures. Submitted to A&A. It includes first referee's comments. Abstract abridged due to arXiv requirement

Certainty relations between local and nonlocal observables

We demonstrate that for an arbitrary number of identical particles, each defined on a Hilbert-space of arbitrary dimension, there exists a whole ladder of relations of complementarity between local, and every conceivable kind of joint (or nonlocal) measurements. E.g., the more accurate we can know (by a measurement) some joint property of three qubits (projecting the state onto a tripartite entangled state), the less accurate some other property, local to the three qubits, become. We also show that the corresponding complementarity relations are particularly tight for particles defined on prime dimensional Hilbert spaces.Comment: 4 pages, no figure

Detection of a large Be circumstellar disk during X-ray quiescence of XTE J1946+274

We present a multiwavelength study of the Be/X-ray binary system XTE J1946+274 with the main goal of better characterizing its behavior during X-ray quiescence. We aim to shed light on the mechanism which triggers the X-ray activity for this source. XTE J1946+274 was observed by Chandra-ACIS during quiescence in 2013 March 12. In addition, this source has been monitored from the ground-based astronomical observatories of El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain) and Sierra Nevada (Granada, Spain) since 2011 September, and from the TUBITAK National Observatory (Antalya, Turkey) since 2005 April. We have performed spectral and photometric temporal analyses in order to investigate the quiescent state and transient behavior of this binary system. In 2006, a long mass ejection event took place from the Be star, lasting for about seven years. We also found that a large Be circumstellar disk was present during quiescence, although major X-ray activity was not observed. We made an attempt to explain this scenario by assuming the permanently presence of a tilted and warped Be circumstellar disk. The 0.3-10 keV X-ray spectrum during quiescence was well fitted with either an absorbed blackbody or absorbed power-law models. The main parameters obtained for these models were kT=1.43+/-0.17 and Gamma=0.9+/-0.4 (with N_H~2-7E+22 cm-2). The 0.3-10 keV flux of the source was ~0.8E-12 erg-1 cm-2 s-1. Pulsations were found with P_pulse=15.757(1) s (MJD 56363.115) and an rms pulse fraction of 32.1(3)%. The observed X-ray luminosity during quiescent periods may be explained by the neutron star being in supersonic propeller regimen.Comment: 9 pages, 7 figures, accepte