Strategic Bidding in Electricity Pools with Short-Lived Bids: An Application to the Spanish Market

We generalize von der Fehr and Harbord’s [Econ. J. 103 (1993) 531] multi-unit auction model for the case of a deterministic demand allowing for any technology mix and elastic demand in order to account for demand-side bidding. We obtain a general characterization of the equilibrium and show that this is bounded above by the Cournot equilibrium. We simulate the Spanish electricity pool and show that price–cost margins substantially increased with the 1996 merger that took the industry from a six-firm structure to its current four-firm structure. Our results show that, in terms of market power, this is similar to a nearly symmetric duopoly. The introduction of demand-side bidding is not likely to change this situation.Publicad

Statistical analysis of Ni nanowires breaking processes: a numerical simulation study

A statistical analysis of the breaking behavior of Ni nanowires is presented. Using molecular dynamic simulations, we have determined the time evolution of both the nanowire atomic structure and its minimum cross section (Sm(t)). Accumulating thousands of independent breaking events, Sm histograms are built and used to study the influence of the temperature, the crystalline stretching direction and the initial nanowire size. The proportion of monomers, dimers and more complex structures at the latest stages of the breaking process are calculated, finding important differences among results obtained for different nanowire orientations and sizes. Three main cases have been observed. (A) [111] stretching direction and large nanowire sizes: the wire evolves from more complex structures to monomers and dimers prior its rupture; well ordered structures is presented during the breaking process. (B) Large nanowires stretched along the [100] and [110] directions: the system mainly breaks from complex structures (low probability of finding monomers and dimers), having disordered regions during their breakage; at room temperature, a huge histogram peak around Sm=5 appears, showing the presence of long staggered pentagonal Ni wires with ...-5-1-5-... structure. (C) Initial wire size is small: strong size effects independently on the temperature and stretching direction. Finally, the local structure around monomers and dimmers do not depend on the stretching direction. These configurations differ from those usually chosen in static studies of conductance.Comment: 18 pages, 13 figure

PopStar Evolutionary Synthesis Models II: Optical emission-line spectra from Giant H{\sc ii} regions

This is the second paper of a series reporting the results from the PopStar evolutionary synthesis models. Here we present synthetic emission line spectra of H{\sc ii} regions photoionized by young star clusters, for seven values of cluster masses and for ages between 0.1 and 5.2 Myr. The ionizing Spectral Energy Distributions (SEDs) are those obtained by the PopStar code \citep*{mgb09} for six different metallicities, with a very low metallicity set, Z=0.0001, not included in previous similar works. We assume that the radius of the H{\sc ii} region is the distance at which the ionized gas is deposited by the action of the mechanical energy of the winds and supernovae from the central ionizing young cluster. In this way the ionization parameter is eliminated as free argument, since now its value is obtained from the cluster physical properties (mass, age and metallicity) and from the gaseous medium characteristics (density and abundances). We discuss our results and compare them with those from previous models and also with a large and data set of giant H{\sc ii} regions for which abundances have been derived in a homogeneous manner. The values of the [OIII] lines (at $\lambda\lambda$ 4363, 4959, 5007\AA) in the lowest metallicity nebulae are found to be very weak and similar to those coming from very high metallicity regions (solar or over-solar). Thus, the sole use of the oxygen lines is not enough to distinguish between very low and very high metallicity regions. In these cases we emphasize the need of the additional support of alternative metallicity tracers, like the [SIII] lines in the near-\textit{IR}.Comment: 20 pages, 26 figures, accepted for publication in MNRAS Main Journa

Genomic Evolution of Two Acinetobacter baumannii Clinical Strains from ST-2 Clones Isolated in 2000 and 2010 (ST-2_clon_2000 and ST-2_clon_2010)

Acinetobacter baumannii is a successful nosocomial pathogen due to its ability to persist in hospital environments by acquiring mobile elements such as transposons, plasmids, and phages. In this study, we compared two genomes of A. baumannii clinical strains isolated in 2000 (ST-2_clon_2000) and 2010 (ST-2_clon_2010) from GenBank project PRJNA308422

Composición de ácidos grasos de la carne de capones de raza Mos y estirpes comerciales sacrificados a diferentes edades

Se ha estudiado la influencia de la raza [Mos (raza española autóctona), Sasso T-44 y X-44 (estirpes comerciales)] y la edad (5, 6, 7 y 8 meses) de los capones (gallos castrados) en la composición de ácidos grasos de la carne de la pechuga y del muslo. La carne de los capones de raza Mos presentó menor concentración de ácidos grasos monoinsaturados y mayor de poliinsaturados que la carne de las otras razas. Además, dichos capones mostraron mayor contenido de los ácidos margárico (C17:0) y esteárico (C18:0) que las estirpes comerciales; sin embargo, no hubo diferencias significativas entre las distintas razas en el total de ácidos grasos saturados. La carne de los animales más jóvenes mostró menor concentración de ácidos grasos monoinsaturados y mayor de poliinsaturados que la de los animales de mayor edad. Sin embargo, la edad influyó menos que la razaThe influence of the breed [Mos (Spanish indigenous breed), Sasso T-44 and X-44 (commercial strains)] and the age (5, 6, 7 and 8 months) of capons (castrated male cockerels) on the fatty acid compositions of breast and drumstick meat were studied. The meat of the Mos capons showed lower contents of monounsaturated fatty acids and higher concentrations of polyunsaturated fatty acids than those of the other breeds. In addition, the Mos breed showed higher contents of margaric acid (C17:0) and stearic acid (C18:0) as compared to the commercial strains; however, no significant effects of breed were observed in the total contents of saturated fatty acids in the meat. The meat of the youngest animals showed lower contents of monounsaturated fatty acids and higher concentrations of polyunsaturated fatty acids than that of the older ones. Nevertheless, the effect of age was less important than the effect of breedThis study was financially supported by project PGIDIT04RAG012E [Consellería de Innovación, Industria e Comercio da Xunta de Galicia and Asociación de Criadores de Capón de Vilalba]S

Extracting Hα\alpha flux from photometric data in the J-PLUS survey

We present the main steps that will be taken to extract H$\alpha$ emission flux from Javalambre Photometric Local Universe Survey (J-PLUS) photometric data. For galaxies with $z\lesssim0.015$, the H$\alpha$+[NII] emission is covered by the J-PLUS narrow-band filter $F660$. We explore three different methods to extract the H$\alpha$ + [NII] flux from J-PLUS photometric data: a combination of a broad-band and a narrow-band filter ($r'$ and $F660$), two broad-band and a narrow-band one ($r'$, $i'$ and $F660$), and a SED-fitting based method using 8 photometric points. To test these methodologies, we simulated J-PLUS data from a sample of 7511 SDSS spectra with measured H$\alpha$ flux. Based on the same sample, we derive two empirical relations to correct the derived H$\alpha$+[NII] flux from dust extinction and [NII] contamination. We find that the only unbiased method is the SED fitting based one. The combination of two filters underestimates the measurements of the H$\alpha$ + [NII] flux by a 28%, while the three filters method by a 9%. We study the error budget of the SED-fitting based method and find that, in addition to the photometric error, our measurements have a systematic uncertainty of a 4.3%. Several sources contribute to this uncertainty: differences between our measurement procedure and the one used to derive the spectroscopic values, the use of simple stellar populations as templates, and the intrinsic errors of the spectra, which were not taken into account. Apart from that, the empirical corrections for dust extinction and [NII] contamination add an extra uncertainty of 14%. Given the J-PLUS photometric system, the best methodology to extract H$\alpha$ + [NII] flux is the SED-fitting based one. Using this method, we are able to recover reliable H$\alpha$ fluxes for thousands of nearby galaxies in a robust and homogeneous way.Comment: 11 pages, 14 figures. Minor changes to match the published versio

Carbon and oxygen in HII regions of the Magellanic Clouds: abundance discrepancy and chemical evolution

We present C and O abundances in the Magellanic Clouds derived from deep spectra of HII regions. The data have been taken with the Ultraviolet-Visual Echelle Spectrograph at the 8.2-m VLT. The sample comprises 5 HII regions in the Large Magellanic Cloud (LMC) and 4 in the Small Magellanic Cloud (SMC). We measure pure recombination lines (RLs) of CII and OII in all the objects, permitting to derive the abundance discrepancy factors (ADFs) for O^2+, as well as their O/H, C/H and C/O ratios. We compare the ADFs with those of other HII regions in different galaxies. The results suggest a possible metallicity dependence of the ADF for the low-metallicity objects, but more uncertain for high-metallicity objects. We compare nebular and B-type stellar abundances and we find that the stellar abundances agree better with the nebular ones derived from collisionally excited lines (CELs). Comparing these results with other galaxies we observe that stellar abundances seem to agree better with the nebular ones derived from CELs in low-metallicity environments and from RLs in high-metallicity environments. The C/H, O/H and C/O ratios show almost flat radial gradients, in contrast with the spiral galaxies where such gradients are negative. We explore the chemical evolution analysing C/O vs. O/H and comparing with the results of HII regions in other galaxies. The LMC seems to show a similar chemical evolution to the external zones of small spiral galaxies and the SMC behaves as a typical star-forming dwarf galaxy.Comment: Accepted for publication in MNRAS, 17 pages, 11 figures, 8 table