On the origin of two unidentified radio/X-ray sources discovered with XMM-Newton

We aim at clarifying the nature of the emission of two spatially related unidentified X-ray sources detected with XMM-Newton telescope at intermediate-low Galactic latitude. Observations reveal a point-like source aligned with elongated diffuse emission. The X-ray spectra are best-fitted by absorbed power laws with photon indices ~1.7 for the point-like and ~2.0 for the extended one. Both sources show nonthermal radio-continuum counterparts that might indicate a physical association. From the available data, we did not detect variability on the point-like source in several timescales. Two possible scenarios are analyzed: first, based on HI line absorption, assuming a Galactic origin, we infer a distance upper bound of <2 kpc, which poses a constraint on the height over the Galactic plane of <200 pc and on the linear size of the system of 10^32 erg/s and >7.5 x 10^32 erg/s, for the point-like and extended sources, respectively; second, an extra-Galactic nature is discussed, where the point-like source might be the core of a radio galaxy and the extended source its lobe. In this case, we compare derived fluxes, spectral indices, and spatial correlation with those typical from the radio galaxy population, showing the feasibility of this alternative astrophysical scenario. From the available observational evidence, we suggest that the most promising scenario to explain the nature of these sources is a system consisting of a one-sided radio galaxy, where the point-like source is an active galactic nucleus and the extended source corresponds to the emission from its lobe. Other possibilities include a PSR/PWN origin, where the radio/X-ray emission originates from the synchrotron cooling of relativistic particles in the PSR magnetic field or a casual alignment between two unrelated sources, such as an AGN core and a Galactic X-ray blob.Comment: 6 pages, 2 figures. Accepted for publication in Astronomy and Astrophysics (A&A

Performance and ownership in the governance of urban water

In this paper the differences in terms of performance between public and the private governance in urban water management are investigated. A statistical ranking is implemented to determine programmatic efficiency differences in DEA, using an incomplete panel data that gathers information on 20 water utilities in Andalusia, in Southern Spain. In the model, labour and operational costs are considered as inputs. The volume of revenue water, the number of connections and the network length are used as outputs. The analysis indicates that private management is more efficient. The efficiency indicators adjusted by a variable related to quality are estimated and demonstrate that privatization of the service does not mean any loss in terms of quality. However, there are no significant differences between both types of management including as a desirable input hydraulic yield as a proxy of the degree of network renovation. A lower hydraulic efficiency in private management would suggest that the need to make significant investments could be an important factor when making the decision to privatize the management of the urban water service: Water supply; Management; Local government;

Fifteen years follow-up of photorefractive keratectomy up to 10 D of myopia: outcomes and analysis of the refractive regression

PURPOSE: To evaluate outcomes of photorefractive keratectomy up to -10.00 D of myopia and -4.50 of astigmatism and to develop a predictive model for the refractive changes in the long term. SETTING: Vissum Corporation and Miguel Hernandez University (Alicante, Spain). DESIGN: Retrospective-prospective observational series of cases. METHODS: This study included 33 eyes of 33 patients aged 46.79±7.04 years (range 40-57) operated with the VISX 20/20 excimer laser with optical zones of 6 mm. No mitomycin C was used in any of these cases. The minimum follow-up was 15 years. The main outcome measures were: uncorrected and corrected distance visual acuity, manifest refraction and corneal topography. Linear regression models were developed from the observed refractive changes over time. RESULTS: Safety and efficacy indexes at 15 years were 1.18 and 0.83, respectively. No statistically significant differences were detected for any keratometric variable during the follow-up (p≥0.103). 15 years after the surgery 54.55% of the eyes were within ±1.00 D of spherical equivalent and 84.85% within ±2.00 D. The uncorrected distance visual acuity at 15 years was 20/25 or better in 60.6% of the eyes and 20/40 or better in 72.73% of the eyes. The correlation between the attempted and the achieved refractions was r=0.948 (p<0.001) at 1 year, and r=0.821 (p<0.001) at 15 years. No corneal ectasia was detected in any case during the follow-up. CONCLUSIONS: Photorefractive keratectomy is a safe refractive procedure in the long term within the range of myopia currently considered suitable for its use, although its efficacy decreases with time, especially, in high myopia. The model developed predicts a myopic regression of 2.00 D at 15 years for an ablation depth of 130 µm

Interbank Rate and the Liquidity of the Market.

In this paper we study the dynamics of the interbank rate in Chile, with special attention to the role of liquidity provided by private depositors and by the central bank’s open market operations on a daily basis. The main aim of this paper is the use of disaggregated and high frequency data on such variables. The most relevant findings are related to the statistical and economic significance of speed of convergence, calendar effects and repos operations. The Central Bank plays a more important role injecting than draining liquidity through discretionary operations. However, there are not asymmetries in terms of the effectiveness of the discretionary injections and drainages operations depending on the liquidity market status. In terms of effect by class of bank, large- and medium-size banks are less receptive to monetary operations; by contrast small-size banks are the most responsive, which is consistent with its traditional position as a liquidity demander. Finally, private deposits do not play an important role on the dynamics of the interbank rate during the sample period.

Effects of Vacancies on Properties of Relaxor Ferroelectrics: a First-Principles Study

A first-principles-based model is developed to investigate the influence of lead vacancies on the properties of relaxor ferroelectric Pb(Sc1/2Nb1/2)O3 (PSN). Lead vacancies generate large, inhomogeneous, electric fields that reduce barriers between energy minima for different polarization directions. This naturally explains why relaxors with significant lead vacancy concentrations have broadened dielectric peaks at lower temperatures, and why lead vacancies smear properties in the neighborhood of the ferroelectric transition in PSN. We also reconsider the conventional wisdom that lead vacancies reduce the magnitude of dielectric response.Comment: 11 pages, 1 figur

Power quality in the Argentine competitive market : Five years of control experience

In this document we show the main advances in Quality Service control, provided by the Distribution companies which supply power for the city of Buenos Aires and its surroundings, involving approximately 5 million customers. We have particularly addressed aspects related to the Technical Product (i.e. voltage level and .distortions) and to the Technical Service (i.e. frequency and duration of interruptions). Controls started in September 1993, one year after the first privatizations were made, by means of performance global indicators of companies, to change, since 1996, into idividual indicators for each customer. We could mention that, as a consequence of controls and penalties imposed, the companies have improved the service quality level, thus evidencing their response to the clear economic signals they received. They have had to make investments, not only in those facilities directly affected to the service supply, but also in the management tools which allowed them to acknowledge the situation and take the necessary correction measures.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Power quality in the Argentine competitive market : Five years of control experience

In this document we show the main advances in Quality Service control, provided by the Distribution companies which supply power for the city of Buenos Aires and its surroundings, involving approximately 5 million customers. We have particularly addressed aspects related to the Technical Product (i.e. voltage level and .distortions) and to the Technical Service (i.e. frequency and duration of interruptions). Controls started in September 1993, one year after the first privatizations were made, by means of performance global indicators of companies, to change, since 1996, into idividual indicators for each customer. We could mention that, as a consequence of controls and penalties imposed, the companies have improved the service quality level, thus evidencing their response to the clear economic signals they received. They have had to make investments, not only in those facilities directly affected to the service supply, but also in the management tools which allowed them to acknowledge the situation and take the necessary correction measures.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE