A white dwarf-neutron star relativistic binary model for soft gamma-ray repeaters

A scenario for SGRs is introduced in which gravitational radiation reaction effects drive the dynamics of an ultrashort orbital period X-ray binary embracing a high-mass donor white dwarf (WD) to a rapidly rotating low magnetised massive neutron star (NS) surrounded by a thick, dense and massive accretion torus. Driven by GR reaction, sparsely, the binary separation reduces, the WD overflows its Roche lobe and the mass transfer drives unstable the accretion disk around the NS. As the binary circular orbital period is a multiple integer number ($m$) of the period of the WD fundamental mode (Pons et al. 2002), the WD is since long pulsating at its fundamental mode; and most of its harmonics, due to the tidal interaction with its NS orbital companion. Hence, when the powerful irradiation glows onto the WD; from the fireball ejected as part of the disk matter slumps onto the NS, it is partially absorbed. This huge energy excites other WD radial ($p$-mode) pulsations (Podsiadlowski 1991,1995). After each mass-transfer episode the binary separation (and orbital period) is augmented significantly (Deloye & Bildsten 2003; Al\'ecyan & Morsink 2004) due to the binary's angular momentum redistribution. Thus a new adiabatic inspiral phase driven by GR reaction starts which brings the binary close again, and the process repeats. This model allows to explain most of SGRs observational features: their recurrent activity, energetics of giant superoutbursts and quiescent stages, and particularly the intriguing subpulses discovered by BeppoSAX (Feroci et al. 1999), which are suggested here to be {\it overtones} of the WD radial fundamental mode (see the accompanying paper: Mosquera Cuesta 2004b).Comment: This paper was submitted as a "Letter to the Editor" of MNRAS in July 17/2004. Since that time no answer or referee report was provided to the Author [MNRAS publication policy limits reviewal process no longer than one month (+/- half more) for the reviewal of this kind of submission). I hope this contribution is not receiving a similar "peer-reviewing" as given to the A. Dar and A. De Rujula's "Cannonball model for gamma-ray bursts", or to the R.K. Williams' "Penrose process for energy extraction from rotating black holes". The author welcomes criticisms and suggestions on this pape

Calibration of GRB Luminosity Relations with Cosmography

For the use of Gamma-Ray Bursts (GRBs) to probe cosmology in a cosmology-independent way, a new method has been proposed to obtain luminosity distances of GRBs by interpolating directly from the Hubble diagram of SNe Ia, and then calibrating GRB relations at high redshift. In this paper, following the basic assumption in the interpolation method that objects at the same redshift should have the same luminosity distance, we propose another approach to calibrate GRB luminosity relations with cosmographic fitting directly from SN Ia data. In cosmography, there is a well-known fitting formula which can reflect the Hubble relation between luminosity distance and redshift with cosmographic parameters which can be fitted from observation data. Using the Cosmographic fitting results from the Union set of SNe Ia, we calibrate five GRB relations using GRB sample at $z\leq1.4$ and deduce distance moduli of GRBs at $1.4< z \leq 6.6$ by generalizing above calibrated relations at high redshift. Finally, we constrain the dark energy parameterization models of the Chevallier-Polarski-Linder (CPL) model, the Jassal-Bagla-Padmanabhan (JBP) model and the Alam model with GRB data at high redshift, as well as with the Cosmic Microwave Background radiation (CMB) and the baryonic acoustic oscillation (BAO) observations, and we find the $\Lambda$CDM model is consistent with the current data in 1-$\sigma$ confidence region.Comment: 15 pages, 4 figures, 2 tables; accepted for publication in IJMP

La franquicia, ¿una oportunidad de negocio?. (Caso de estudio)

EN ESTE CASO SE PRESENTAN LAS SIGUIENTES SITUACIOES: En este caso se plasma la decisión de inversión de una persona del común, que vive la situación actual del país y que por cuestiones de la recesión económica y otros factores de orden político que vive actualmente la economía colombiana fue liquidado de la empresa en la cual laboraba; situación que le hace pensar en cual es la mejor manera de invertir el dinero obtenido por su liquidación y decidir su ocupación de aquí en adelante. Esta persona trabajo en el sector automotriz por lo cual posee un conocimiento, que decide aprovechar y toma la decisión de montar un negocio para la prestación de servicios automotrices. Al tomar esta decisión encuentra que el mercado le ofrece diferentes alternativas entre las cuales y de acuerdo a su presupuesto decide evaluar si establece su negocio a través de una Franquicia o establece el negocio como persona independiente. Finalmente decidirá cual de las dos opciones es la más adecuada para invertir su dinero. Teniendo en cuenta las variables financieras y los aspectos no financieros en la evaluación del proyecto para la toma de su decisión

Silvopastoral Systems: Analyses of an Alternative to Open Swards

Silvopasture is a sustainable land use management practiced in most continents in the world including parts of southern Europe, but is not broadly used in northern and western Europe. The importance of this practice has been recognised and the last draft of the EU regulation by the European Agricultural Fund for Rural Development (http://europa.eu.int/comm/agriculture/capreform/rurdevprop_en.pdf) includes specifically funding for establishment of agroforestry practices in Europe. This paper discusses the advantages of managing semi intensive grassland within a silvopastoral system from an ecological, productive and social point of view in the south, south-central and western countries of Europe

Nonlinear electrodynamics and the surface redshift of pulsars

Currently is argued that the best method of determining the neutron star (NS) fundamental properties is by measuring the {\it gravitational redshift} ($z$) of spectral lines produced in the star photosphere. Measurement of $z$ at the star surface provides a unique insight on the NS mass-to-radius relation and thus on its equation of state (EoS), which reflects the physics of the strong interaction between particles making up the star. Evidence for such a measurement has been provided quite recently by Cottam, Paerels & Mendez (2002), and also by Sanwal et {\it al.} (2002). Here we argue that although the quoted observations are undisputed for canonical pulsars, they could be misidentified if the NS is endowed with a super strong $B$ as in the so-called magnetars (Duncan & Thompson 1992) and strange quark magnetars (Zhang 2002), as in the spectral line discovered by Ibrahim et {\it al.} (2002;2003). The source of this new "confusion" redshift is related to nonlinear electrodynamics (NLEDs) effects.Comment: 5 pages, emulateapj.sty, accepted for publication in Astrophysical Journa

Measuring Microlensing using Spectra of Multiply Lensed Quasars

We report on a program of spectroscopic observations of gravitationally-lensed QSOs with multiple images. We seek to establish whether microlensing is occurring in each QSO image using only single-epoch observations. We calculate flux ratios for the cores of emission lines in image pairs to set a baseline for no microlensing. The offset of the continuum flux ratios relative to this baseline yields the microlensing magnification free from extinction, as extinction affects the continuum and the lines equally. When we find chromatic microlensing, we attempt to constrain the size of the QSO accretion disk. SDSSJ1004+4112 and HE1104-1805 show chromatic microlensing with amplitudes $0.2< |\Delta m| < 0.6$ and $0.2< |\Delta m| < 0.4$ mag, respectively. Modeling the accretion disk with a Gaussian source ($I\propto \exp(-R^2/2r_s^2)$) of size $r_s\propto \lambda^p$ and using magnification maps to simulate microlensing we find $r_s(\lambda 3363)=7\pm3 light-days (18.1\pm7.8 \times 10^{15} cm$) and $p=1.1\pm 0.4$ for SDSS1004+4112, and $r_s(\lambda 3363)=6\pm2 light-days (15.5\pm5.2 \times 10^{15} cm$) and $p=0.7\pm0.1$ for HE1104-1805. For SDSSJ1029+2623 we find strong chromaticity of $\sim 0.4$ mag in the continuum flux ratio, which probably arises from microlensing although not all the available data fit within this explanation. For Q0957+561 we measure B-A magnitude differences of 0.4 mag, much greater than the $\sim$0.05 mag amplitude usually inferred from lightcurve variability. It may substantially modify the current interpretations of microlensing in this system, likely favoring the hypothesis of smaller sources and/or larger microdeflectors. For HS0818+1227, our data yield posible evidence of microlensing.Comment: 45pp, 17figs, ApJ accepted (june 4th 2012

Enhanced Recovery after Surgery in a Single High-Volume Surgical Oncology Unit: Details Matter

Benefits of ERAS protocol have been well documented; however, it is unclear whether the improvement stems from the protocol or shifts in expectations. Interdisciplinary educational seminars were conducted for all health professionals. However, one test surgeon adopted the protocol. 394 patients undergoing elective abdominal surgery from June 2013 to April 2015 with a median age of 63 years were included. The implementation of ERAS protocol resulted in a decrease in the length of stay (LOS) and mortality, whereas the difference in cost was found to be insignificant. For the test surgeon, ERAS was associated with decreased LOS, cost, and mortality. For the control providers, the LOS, cost, mortality, readmission rates, and complications remained similar both before and after the implementation of ERAS. An ERAS protocol on the single high-volume surgical unit decreased the cost, LOS, and mortality

Cosmological Model-independent Gamma-ray Bursts Calibration and its Cosmological Constraint to Dark Energy

As so far, the redshift of Gamma-ray bursts (GRBs) can extend to $z\sim 8$ which makes it as a complementary probe of dark energy to supernova Ia (SN Ia). However, the calibration of GRBs is still a big challenge when they are used to constrain cosmological models. Though, the absolute magnitude of GRBs is still unknown, the slopes of GRBs correlations can be used as a useful constraint to dark energy in a completely cosmological model independent way. In this paper, we follow Wang's model-independent distance measurement method and calculate their values by using 109 GRBs events via the so-called Amati relation. Then, we use the obtained model-independent distances to constrain $\Lambda$CDM model as an example.Comment: 16 pages, 5 figure