Laser radiation as an adjunct to nonsurgical treatment of periodontal disease.

Peer Reviewe

Formation of asymmetric arms in barred galaxies

ABSTRACTWe establish a dynamical mechanism to explain the origin of the asymmetry between the arms observed in some barred disc galaxies, where one of the two arms emanating from the bar ends is very well defined, while the second one displays a ragged structure, extending between its ridge and the bar. To this purpose, we study the invariant manifolds associated with the Lyapunov periodic orbits around the unstable equilibrium points at the ends of the bar. Matter from the galaxy centre is transported along these manifolds to the periphery, forming this way the spiral arms that emanate from the bar ends. If the mass distribution in the galaxy centre is not homogeneous, because of an asymmetric bar with one side stronger than the other, or because of a non-centred bulge, the dynamics about the two unstable Lagrange points at the ends of the bar will not be symmetric as well. One of their invariant manifolds becomes more extended than the other, enclosing a smaller section and the escaping orbits on it are fewer and dispersed in a wider region. The result is a weaker arm and more ragged than the one at the other end of the bar

Forming first-ranked early-type galaxies through hierarchical dissipationless merging

We have developed a computationally competitive N-body model of a previrialized aggregation of galaxies in a flat LambdaCDM universe to assess the role of the multiple mergers that take place during the formation stage of such systems in the configuration of the remnants assembled at their centres. An analysis of a suite of 48 simulations of low-mass forming groups (of about 1E13 solar masses) demonstrates that the gravitational dynamics involved in their hierarchical collapse is capable of creating realistic first-ranked galaxies without the aid of dissipative processes. Our simulations indicate that the brightest group galaxies (BGGs) constitute a distinct population from other group members, sketching a scenario in which the assembly path of these objects is dictated largely by the formation of their host system. We detect significant differences in the distribution of Sersic indices and total magnitudes, as well as a luminosity gap between BGGs and the next brightest galaxy that is positively correlated with the total luminosity of the parent group. Such gaps arise from both the grow of BGGs at the expense of lesser companions and the decrease in the relevance of second-ranked objects in equal measure. This results in a dearth of intermediate-mass galaxies which explains the characteristic central dip detected in their luminosity functions in dynamically young galaxy aggregations. The fact that the basic global properties of our BGGs define a thin mass fundamental plane strikingly similar to that followed giant early-type galaxies in the local universe reinforces confidence in the results obtained.Comment: 25 pages, 14 figures, 3 tables. Accepted to MNRA

Benchmarking CPUs and GPUs on embedded platforms for software receiver usage

Smartphones containing multi-core central processing units (CPUs) and powerful many-core graphics processing units (GPUs) bring supercomputing technology into your pocket (or into our embedded devices). This can be exploited to produce power-efficient, customized receivers with flexible correlation schemes and more advanced positioning techniques. For example, promising techniques such as the Direct Position Estimation paradigm or usage of tracking solutions based on particle filtering, seem to be very appealing in challenging environments but are likewise computationally quite demanding. This article sheds some light onto recent embedded processor developments, benchmarks Fast Fourier Transform (FFT) and correlation algorithms on representative embedded platforms and relates the results to the use in GNSS software radios. The use of embedded CPUs for signal tracking seems to be straight forward, but more research is required to fully achieve the nominal peak performance of an embedded GPU for FFT computation. Also the electrical power consumption is measured in certain load levels.Peer ReviewedPostprint (published version

Redescription of Caprella hirsuta Mayec 1890 (Crustacea, Amphipoda, Caprellidea) from the Strait of Gibraltar

Caprella hirsuta Mayer, 1890 is redescribed based on specimens collected from the Strait of Gibraltar (Southern Spain-Northern Africa) during a study of the amphipod fauna from these coasts. Careful examination of these caprellids revealed differences with the previous descriptions, mainly the structure of gnathopod 2, pereopods and abdomen. Key words: Crustacea, Amphipoda, Caprellidea, Caprella hirsuta, Strait of Gibraltar, Redescription.Caprella hirsuta Mayer, 1890 is redescribed based on specimens collected from the Strait of Gibraltar (Southern Spain-Northern Africa) during a study of the amphipod fauna from these coasts. Careful examination of these caprellids revealed differences with the previous descriptions, mainly the structure of gnathopod 2, pereopods and abdomen. Key words: Crustacea, Amphipoda, Caprellidea, Caprella hirsuta, Strait of Gibraltar, Redescription.Caprella hirsuta Mayer, 1890 is redescribed based on specimens collected from the Strait of Gibraltar (Southern Spain-Northern Africa) during a study of the amphipod fauna from these coasts. Careful examination of these caprellids revealed differences with the previous descriptions, mainly the structure of gnathopod 2, pereopods and abdomen. Key words: Crustacea, Amphipoda, Caprellidea, Caprella hirsuta, Strait of Gibraltar, Redescription

Conservation status and updated census of Patella ferruginea (Gastropoda, Patellidae) in Ceuta: distribution patterns and new evidence of the effects of environmental parameters on population structure

The Strait of Gibraltar has important populations of the highly endangered patellid limpet Patella ferruginea. Between 2006 and 2010, an exhaustive census was carried out in Ceuta. The total coastline was divided into 17 sectors. The coast of each sector was examined by using 10 m transects. For the case of those sectors composed of breakwaters, jetties or islets, no transects were used, and instead, the total number of individuals was recorded. Each individual was measured to the nearest millimetre using a calliper. Moreover, the complete rocky shore length where the species could potentially be present was calculated, and an estimation of the total number of individuals that each sector could host was made. Results indicate that Ceuta could be home to around 44,000 individuals. The species found in Point Benzú, its westernmost limit of distribution on the North African coasts. The largest populations were recorded on the South Bay, with higher Mediterranean influence. Our results indicate that substrate roughness (topographic heterogeneity) and the area’s accessibility highly influence the abundance and population structure. Those populations located on high topographic heterogeneity substrates show higher recruitment rates and lower percentages of larger individuals, while medium to low rugosity surfaces presented the opposite pattern. Additionally, easily accessible areas (and frequented by humans) presented smaller average shell sizes. Implications of the results for conservation purposes are discussed

The management of lifeguards in natural acuatic spaces (beaches)

Este estudio nace con la necesidad de establecer criterios básicos y descripción de recomendaciones para mejorar el nivel de atención de los socorristas acuáticos profesionales en los espacios acuáticos naturales, concretamente en el trabajo realizado en las playas, con el objetivo de aumentar la seguridad de estas zonas de baño. El estudio se ha desarrollado en la Comunidad Autónoma de Cataluña, concretamente en tres playas de varios municipios de la provincia de Barcelona. Se puede afirmar que tras esta investigación la mayor parte de los socorristas acuáticos que han participado en el estudio valoraron positivamente las medidas y criterios propuestos, asumiendo que con los mismos se puede desempeñar mejor su trabajoThis study arises from the need to establish basic criteria and the description of recommendations to improve the level of responsiveness of lifeguards in natural aquatic areas, specifically in the work done on the beaches, in order to increase the safety of these bathing areas. The study was developed Cataluña, in three beaches of different municipalities in the province of Barcelona. We can aver after this research that most of the lifeguards who participated in the study value positively the proposed measures and criteria, through the assumption that these features help improve their wor

Gender differences in adventure tourists who practice kayaking in Extremadura

Adventure tourism is among the sectors that has experienced the greatest growth in participation in recent years. In addition, it provides a unique opportunity to generate different benefits for rural populations as well as for the preservation of their environment. The objective of this study was to analyze gender differences in the profile, estimated expenditure, perception of economic impact and satisfaction of adventure tourists visiting the Valle del Jerte (Extremadura, Spain) for kayaking activities. The sample was composed of 511 tourists who kayaked in the Valle del Jerte. Gender differences were analyzed by the Mann-Whitney U test in continuous variables and Pearson’s chi-square test in categorical variables. The predominant profile of the kayaking tourist is Spanish, married, employed, with university education, lives with their partner with children at home, chooses a rural home for accommodation, travels with companions, uses their own car for transportation, spends 550 euros on average, has good perceptions of the economic impact of the activity on the destination and is satisfied with the kayak service received. This information is relevant for public and private organizations as well as for the local community to be able to offer services more oriented to the tourist who engages in these activities, as well as to attract more tourists

The abundances and distributions of molluscs in the southern Iberian Peninsula: A comparison of marine and terrestrial systems

Molluscs are the second most diverse of all animal phyla, and occur in many habitat types. They are, therefore, a particularly good phylum with which to compare and contrast differences between ecosystems. Mollusc data from a number of sites along the southern coast of the Iberian Peninsula are analysed to study patterns of diversity and distribution using a range of multivariate techniques. Within each site, data are presented from three locations -fully terrestrial, rocky intertidal and soft bottom benthic (10 m and 20 m depths)- all in close proximity. The species are then classified in relation to morphology and size, and analysed at supraspecific levels to elucidate underlying patterns. The observed patterns are briefly discussed, with particular reference to the differential scope and importance of controlling factors in each ecosystem, such as dispersal processes. The results from the systems are compared and discussed in the context of ecological and evolutionary constraints in Mollusca.Los moluscos constituyen el segundo filo animal más diverso y se encuentran en muchos tipos de hábitat, por lo que son idóneos para establecer comparaciones entre distintos ecosistemas. Se han analizado los datos de los moluscos obtenidos en una serie de emplazamientos que cubrían el sur de la península Ibérica para determinar, empleando distintas técnicas multivariantes, los patrones de diversidad y distribución de estos organismos. Los datos se tomaron de ejemplares capturados en lugares del medio terrestre próximos a la línea de costa, de la franja intermareal rocosa y de sedimentos de fondos marinos situados a 10 y 20 m de profundidad. Las especies fueron clasificadas atendiendo a la morfología y el tamaño, y se analizaron a nivel supraespecífico para elucidar los patrones generales, que se discuten aquí, brevemente, con especial énfasis en las diferencias según la importancia de los factores que controlan cada ecosistema, como, por ejemplo, los procesos de dispersión. Los resultados de los distintos sistemas se comparan y discuten en el contexto de las tendencias ecológicas y evolutivas de los moluscos.Instituto Español de Oceanografí