V405 Peg (RBS 1955): A Nearby, Low-Luminosity Cataclysmic Binary

(Abridged). The cataclysmic binary V405 Peg, originally discovered as ROSAT Bright Source (RBS) 1955 (= 1RXS J230949.6+213523), shows a strong contribution from a late-type secondary star in its optical spectrum, which led Schwope et al. to suggest it to be among the nearest cataclysmic binaries. We present extensive optical observations of V405 Peg. Time-series spectroscopy shows the orbital period, Porb, to be 0.1776469(7) d (= 4.2635 hr), or 5.629 cycle/d. We classify the secondary as M3 - M4.5. Astrometry with the MDM 2.4m telescope gives a parallax 7.2 +- 1.1 milli-arcsec, and a relative proper motion of 58 mas/yr. Our best estimate of the distance yields d = 149 (+26, -20) pc. The secondary stars's radial velocity has K2 = 92 +- 3 km/s, indicating a fairly low orbital inclination if the masses are typical. Extensive I-band time-series observations in the show the system varying between a minimum brightness level of I = 14.14 and states of enhanced activity about 0.2 mag brighter. While the low-state shows an ellipsoidal modulation, an additional photometric modulation appears in the high state, with 0.1 mag amplitude and period 220-280 min. The frequency of this modulation appears to be stable for a month or so, but no single period was consistently detected from one observing season to the next. We estimate the system luminosity by combining optical measurements with the archival X-ray spectrum. The implied mass accretion rate is orders of magnitudes below the predictions for the standard angular momentum loss above the period gap. The system may possibly belong to a largely undiscovered population of hibernating CVs.Comment: 11 figures; 7 of these are .png or .jpg to save space. In press for Publications of the Astronomical Society of the Pacifi

Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: comparison with the SDSS DR7 observed sample

Detached white dwarf + main sequence (WD+MS) systems represent the simplest population of post-common envelope binaries (PCEBs). Since the ensemble properties of this population carries important information about the characteristics of the common-envelope (CE) phase, it deserves close scrutiny. However, most population synthesis studies do not fully take into account the effects of the observational selection biases of the samples used to compare with the theoretical simulations. Here we present the results of a set of detailed Monte Carlo simulations of the population of WD+MS binaries in the Sloan Digital Sky Survey (SDSS) Data Release 7. We used up-to-date stellar evolutionary models, a complete treatment of the Roche lobe overflow episode, and a full implementation of the orbital evolution of the binary systems. Moreover, in our treatment we took into account the selection criteria and all the known observational biases. Our population synthesis study allowed us to make a meaningful comparison with the available observational data. In particular, we examined the CE efficiency, the possible contribution of internal energy, and the initial mass ratio distribution (IMRD) of the binary systems. We found that our simulations correctly reproduce the properties of the observed distribution of WD+MS PCEBs. In particular, we found that once the observational biases are carefully taken into account, the distribution of orbital periods and of masses of the WD and MS stars can be correctly reproduced for several choices of the free parameters and different IMRDs, although models in which a moderate fraction (<=10%) of the internal energy is used to eject the CE and in which a low value of CE efficiency is used (<=0.3) seem to fit better the observational data. We also found that systems with He-core WDs are over-represented in the observed sample, due to selection effects.Comment: 15 pages, 7 figures, accepted for publication in A&

Nuevas aportaciones al estudio polínico de sedimentos del Parque Natural de los Alcornocales (Cádiz, sur de España)

Nuevas apotaciones al estudio polínico de sedimentos del Parque Natural de los Alcornocales (Cádiz, Sur de España). En este trabajo se completa el contenido polínico de una columna de sedimento de 300 cm, extraida de una zona semiturbosa de la Sierra del Aljibe en el Parque Natural de los Alcornocales (Cádiz). Se discuten las variaciones polínicas porcentuales de los taxones identificados, consideradas de nuevo aquí a la luz de los nuevos datos, fundamentalmente la datación con radiocarbono, y se interpretan los diagramas polínicos resultantes en términos paleoecológicos. Por otro lado, y en base a estudios previos en el norte de Marruecos, zona de características ecológicas e históricas similares a la zona estudiada, se concluye el uso diferente del territorio a ambos lados del estrecho

Estudio comparativo de la incidencia de la Directiva Seveso por ámbitos territoriales. El caso particular de la región de Andalucía

Desde la entrada en vigor de la primera Directiva Seveso en Europa, el concepto de prevención de accidentes graves por sustancias peligrosas ha evolucionado de forma diferente dependiendo de la transposición particular de cada Estado Miembro a su propio ordenamiento jurídico. Adicionalmente, cada región con competencias en materia de seguridad industrial o protección civil ha contribuido, aún más, a la dispersión normativa existente lo que no favorece una regulación de forma universal o estándar. Uno de los aspectos normativos merecedor de una profunda actualización ante la próxima puesta en vigor de la nueva Directiva Seveso III, es aquel que incide sobre las zonas de influencia donde existen establecimientos industriales afectados por la Directiva. En el presente trabajo se va a realizar una evolución histórica de la afectación por ámbito geográfico en la década 2002-2012. El análisis territorial comienza con la distribución geográfica de laafectación en la Unión Europea. De manera similar, se vadescendiendo geográficamente hasta estudiar el estadoespañol y, finalmente, alcanzará a la región de Andalucíadonde, se profundizará aún más, hasta alcanzar el nivelterritorial de provincias y, municipios. Del análisis se deducenunas primeras conclusiones particulares relativas tanto a las concentraciones de establecimientos Seveso y de los sectores industriales más significativos cubiertos por dicha normativa

Small violations of unitarity, the phase in Bs mixing and visible t->cZ decays at the LHC

We show that it is possible to accommodate the observed size of the phase in $B^0_s$--$\bar B^0_s$, mixing in the framework of a model with violation of $3\times 3$ unitarity. This violation is associated to the presence of a new $Q=2/3$ isosinglet quark $T$, which mixes both with $t$ and $c$ and has a mass not exceeding 500 GeV. The crucial point is the fact that this framework allows for $\chi\equiv\arg(-V_{ts}V_{cb}V_{tb}^*V_{cs}^*)$ of order $\lambda$, to be contrasted with the situation in the Standard Model, where $\chi$ is constrained to be of order $\lambda^2$. We point out that this scenario implies rare top decays $t\to cZ$ at a rate observable at the LHC and $|V_{tb}|$ significantly different from unity. In this framework, one may also account for the observed size of $D^0$--$\bar D^0$ mixing without having to invoke long distance contributions. It is also shown that in the present scenario, the observed size of $D^0$--$\bar D^0$ mixing constrains $\chi^\prime\equiv\arg(-V_{cd}V_{us}V_{cs}^*V_{ud}^*)$ to be of order $\lambda^4$, which is significantly smaller than what is allowed in generic models with violations of $3\times 3$ unitarity.Comment: 20 pages. References added. Additional observables considered, updated numerical examples, conclusions unchange

Fauna malacológica de Les Planes de Son y La Mata de València (Alt Àneu, Pallars Sobirà, Pirineo Catalán): revisión biliográfica y nuevos datos

La revisió de citacions bibliogràfiques situades a les Planes de Son i la Mata de València (municipi d’Alt Àneu, Pallars Sobirà) ha permès identificar 33 espècies de mol·luscs (set de les quals corresponents a llimacs) presents històricament en la zona. Una campanya de camp portada a terme recentment (2006–2007) ha detectat 50 espècies de mol·luscs no-llimacs, dues de les quals representades amb dues subespècies cadascuna. Es proporcionen les dades detallades dels dos inventaris faunístics. Paraules clau: Pirineus, Fauna, Mollusca.The survey of bibliograpic information on the presence of molluscs at the Planes de Son and Mata de València (municipality of Alt Àneu, county of Pallars Sobirà, Catalan Pyrenees) has accounted for a list of 33 species of molluscs (seven of them are slugs) inhabiting historically this area. A current field survey (2006-2007) has detected 50 species of molluscs not slugs, two of these species are splitted in two subspecies. Detailed data from both faunistic inventories are provided. Key words: Pyrenees, Fauna, Mollusca.La revisión de las citas bibliográficas situadas en Les Planes de Son y La Mata de València (municipio de Alt Àneu, comarca del Pallars Sobirà, Pirineo Catalán) ha permitido identificar 33 especies de moluscos (siete de ellas correspondientes a babosas) presentes históricamente en la zona. Una reciente campaña de campo (2006-2007) ha detectado 50 especies de moluscos no babosas, dos de ellas representadas con dos subespecies cada una. Se proporcionan los datos detallados de los dos inventarios faunísticos. Palabras clave: Pirineo, Fauna, Mollusca

Influencia de la altitud en la riqueza de especies de moluscos: variaciones en el valle de Alinyà, Alt Urgell, Lleida

The species richness of land molluscs is negatively correlated with altitude, while the altitudinal range of the species inhabiting at higher elevations is greater than in low levels. At the low scale of this study factors other than elevation may account better for the species richness.La riqueza de especies de moluscos terrestres está negativamente correlacionada con la altitud, mientras que el rango altitudinal de las especies lo está positivamente. En estudios locales como éste la altitud no explica suficientemente la distribución de la riqueza de especies

The changing accretion states of the intermediate polar MU Camelopardalis

We study the timing and spectral properties of the intermediate polar MU Camelopardalis (1RXS J062518.2+733433) to determine the accretion modes and the accretion geometry from multi-wavelength, multi-epoch observational data. Light curves in different observed energy ranges (optical, UV, X-ray) are extracted. The timescales of variability in these light curves are determined using Analysis of Variance. Phase-resolved X-ray spectra are created with respect to the most prominent detected periodicities and each fitted with an identical model, to quantify the differences in the fitted components. The published tentative value for the spin period is unambiguously identified with the rotation period of the white dwarf. We detect a distinct soft X-ray component that can be reproduced well by a black body. The analysis of data obtained at different epochs demonstrates that the system is changing its accretion geometry from disk-dominated to a combination of disk- plus stream-dominated, accompanied with a significant change in brightness at optical wavelengths.Comment: Accepted for publication in Astron. Astrophys., 13 pages, 10 figure

Efficacy of different antifouling treatments for seawater cooling systems

In an industrial seawater cooling system, the effects of three different antifouling treatments, viz. sodium hypochlorite (NaClO), aliphatic amines (Mexel1432) and UV radiation, on the characteristics of the fouling formed were evaluated. For this study a portable pilot plant, as a side-stream monitoring system and seawater cooling system, was employed. The pilot plant simulated a power plant steam condenser, having four titanium tubes under different treatment patterns, where fouling progression could be monitored. The nature of the fouling obtained was chiefly inorganic, showing a clear dependence on the antifouling treatment employed. After 72 days the tubes under treatment showed a reduction in the heat transfer resistance (R) of around 70% for NaClO, 48% for aliphatic amines and 55% for UV, with respect to the untreated tube. The use of a logistic model was very useful for predicting the fouling progression and the maximum asymptotic value of the increment in the heat transfer resistance (DRmax). The apparent thermal conductivity (l) of the fouling layer showed a direct relationship with the percentage of organic matter in the collected fouling. The characteristics and mode of action of the different treatments used led to fouling with diverse physicochemical properties