Características de la anidación de la tortuga verde Chelonia mydas (Testudinata, Cheloniidae) en la playa Caleta de los Piojos, Cuba, a partir de marcaciones externas

Green turtle (Chelonia mydas) females nesting during 2002 and 2003 nesting seasons at Caleta de los Piojos Beach, Cuba, were studied using data from individual tagging. Nesting occurred on average twice per season with a mean interval of 10.9 days. A high number of turtles nested only once per season (39% and 40% respectively). The percentage of failed multiple nesting attempts was high in both seasons. However, the percentage of failed attempts prior to the first nesting was higher in the 2003 season. Vegetation areas seem to be the most suitable sites for nesting and have a significant effect on nest–site selection behaviour. Fidelity to first nest–site was high, 50.3% and 72.9% respectively for 2002 and 2003. Observed mean clutch size (117 eggs) was closely related to body dimensions. Key words: Green turtle, Chelonia mydas, Nesting, Tagging, Guanahacabibes Peninsula.En el presente estudio se caracterizan aspectos reproductivos de las hembras de tortuga verde (Chelonia mydas), que anidaron entre los años 2002 y 2003, en la playa Caleta de los Piojos, Cuba. Se utiliza la información recopilada a partir de la colocación de marcas metálicas en cada tortuga observada. Durante las temporadas en estudio se comprobó que las tortugas anidan dos veces como promedio, con intervalo de 10.9 días. Un gran número de tortugas anidaron sólo una vez en toda la etapa reproductiva (39% y 40% respectivamente). El mayor porcentaje de intentos fallidos de anidación para ambos años ocurrió entre anidaciones consecutivas. Sin embargo en la temporada de anidación 2003 se observó un mayor porcentaje de intentos fallidos antes de la primera anidación, respecto al año 2002. La zona de vegetación fue la más utilizada para la anidación y tiene un efecto significativo en la conducta de selección del sitio de anidación. Se observó un 50,3% y 72,9% respectivamente para 2002 y 2003, de fidelidad al lugar de primera anidación. El tamaño promedio de la nidada (117 huevos) depende de las dimensiones corporales de la hembra anidadora. Palabras clave: Tortuga verde, Chelonia mydas, Anidación, Marcación, Península de Guanahacabibes

PPAK Wide-field Integral Field Spectroscopy of NGC 628: II. Emission line abundance analysis

In this second paper of the series, we present the 2-dimensional (2D) emission line abundance analysis of NGC 628, the largest object within the PPAK Integral Field Spectroscopy (IFS) Nearby Galaxies Survey: PINGS. We introduce the methodology applied to the 2D IFS data in order to extract and deal with large spectral samples, from which a 2D abundance analysis can be later performed. We obtain the most complete and reliable abundance gradient of the galaxy up-to-date, by using the largest number of spectroscopic points sampled in the galaxy, and by comparing the statistical significance of different strong-line metallicity indicators. We find features not previously reported for this galaxy that imply a multi-modality of the abundance gradient consistent with a nearly flat-distribution in the innermost regions of the galaxy, a steep negative gradient along the disc and a shallow gradient or nearly-constant metallicity beyond the optical edge of the galaxy. The N/O ratio seems to follow the same radial behaviour. We demonstrate that the observed dispersion in metallicity shows no systematic dependence with the spatial position, signal-to-noise or ionization conditions, implying that the scatter in abundance for a given radius is reflecting a true spatial physical variation of the oxygen content. Furthermore, by exploiting the 2D IFS data, we were able to construct the 2D metallicity structure of the galaxy, detecting regions of metal enhancement, and showing that they vary depending on the choice of the metallicity estimator. The analysis of axisymmetric variations in the disc of NGC 628 suggest that the physical conditions and the star formation history of different-symmetric regions of the galaxy have evolved in a different manner.Comment: Accepted for publication in MNRAS, 40 pages, 22 figures, online data: http://www.ast.cam.ac.uk/ioa/research/ping

The role of gas infall in the evolution of disc galaxies

Spiral galaxies are thought to acquire their gas through a protracted infall phase resulting in the inside-out growth of their associated discs. For field spirals, this infall occurs in the lower density environments of the cosmic web. The overall infall rate, as well as the galactocentric radius at which this infall is incorporated into the star-forming disc, plays a pivotal role in shaping the characteristics observed today. Indeed, characterising the functional form of this spatio-temporal infall in-situ is exceedingly difficult, and one is forced to constrain these forms using the present day state of galaxies with model or simulation predictions. We present the infall rates used as input to a grid of chemical evolution models spanning the mass spectrum of discs observed today. We provide a systematic comparison with alternate analytical infall schemes in the literature, including a first comparison with cosmological simulations. Identifying the degeneracies associated with the adopted infall rate prescriptions in galaxy models is an important step in the development of a consistent picture of disc galaxy formation and evolution.Comment: 12 pages, 12 figures, MNRAS, accepte

The role of gas infall in the evolution of disc galaxies

Spiral galaxies are thought to acquire their gas through a protracted infall phase resulting in the inside-out growth of their associated discs. For field spirals, this infall occurs in the lower density environments of the cosmic web. The overall infall rate, as well as the galactocentric radius at which this infall is incorporated into the star-forming disc, plays a pivotal role in shaping the characteristics observed today. Indeed, characterising the functional form of this spatio-temporal infall in-situ is exceedingly difficult, and one is forced to constrain these forms using the present day state of galaxies with model or simulation predictions. We present the infall rates used as input to a grid of chemical evolution models spanning the mass spectrum of discs observed today. We provide a systematic comparison with alternate analytical infall schemes in the literature, including a first comparison with cosmological simulations. Identifying the degeneracies associated with the adopted infall rate prescriptions in galaxy models is an important step in the development of a consistent picture of disc galaxy formation and evolution

Integrating The Five Practices of Exemplary Leadership Model into Entrepreneurship Education

Entrepreneurship educators can assess their students by focusing on leadership self-efficacy dimensions that align with desirable entrepreneurship behaviors. To support this claim, we used the Student Leadership Practices Inventory (S-LPI) to survey a group of 46 undergraduate students in Mexico and 49 undergraduate students in Spain that were involved in entrepreneurship education programs. Independent samples t-tests show statistically significant differences between the two groups. We also compared the whole sample in terms of gender and found no differences. We propose that educators integrate Five Practices of Exemplary Leadership model into de design and assessment of their curricular and co-curricular entrepreneurship development programs. Specifically, the model serves educators from different countries, in this case Mexico and Spain, by identifying the leadership behaviors that their students enact. By integrating the five practices of exemplary leadership model, educators can account for variables like nation of origin and gender, and identify differences between groups

Optimization of actuation and cooling systems for advanced convergent-divergent nozzles of combat aircraft

The system or components of a convergent-divergent (CONDI) nozzle that offer better perspectives for improvement and optimization are the actuation and cooling systems. Performance offers little margin for a direct improvement, and the utilization of advanced materials in many components of the nozzle presents no specific problems as compared with those of other parts of the engine, with the exception of the petals, in which the introduction of ceramic materials has a direct influence on cooling and performance, and it will be included in the cooling optimization. The introduction of a thrust vectoring capability is a major improvement, though not the subjet of this paper. The problem of the optimization of the actuation system was preliminary discussed in ref. 1, mainly in connection with the utilization of one versus two parameters actuation system. Since that time, SENER and FTP have carried out many studies and tests on actuation systems and on cooling optimization. They have also accumulated experience by means of theoretical and experimental studies on the utilization of ceramic petals. Some results and the main conclusions of these studies and tests are presented in the present work

Thermal effects on the structure and relaxation properties of poly(monocyclopentyl itaconate)

[EN] The effect of thermal treatment and subsequent chemical structural modifications on the viscoelastic and dielectric properties of PMCPI (poly(monocyclopentyl itaconate)) was studied. The low temperature relaxation (gamma-relaxation) is unaffected by the thermal history or chemical modifications. The intermediate relaxation (beta-relaxation) is shifted by about 40 degrees C to higher temperature after thermal treatment. The alpha-relaxation (related to the glass transition temperature T-g) suffers more striking changes when moving to higher temperatures.Díaz Calleja, R.; Sanchis Sánchez, MJ.; Gargallo, L.; Radic, D. (1995). Thermal effects on the structure and relaxation properties of poly(monocyclopentyl itaconate). Macromolecular Chemistry and Physics. 196(11):3789-3796. doi:10.1002/macp.1995.021961129S378937961961

Secure store and forward proxy for dynamic IoT applications over M2M networks

Internet of Things (IoT) applications are expected to generate a huge unforeseen amount of traffic flowing from Consumer Electronics devices to the network. In order to overcome existing interoperability problems, several standardization bodies have joined to bring a new generation of Machine to Machine (M2M) networks as a result of the evolution of wireless sensor/actor networks and mobile cellular networks to converged networks. M2M is expected to enable IoT paradigms and related concepts into a reality at a reasonable cost. As part of the convergence, several technologies preventing new IoT services to interfere with existing Internet services are flourishing. Responsive, message-driven, resilient and elastic architectures are becoming essential parts of the system. These architectures will control the entire data flow for an IoT system requiring sometimes to store, shape and forward data among nodes of a M2M network to improve network performance. However, IoT generated data have an important personal component since it is generated in personal devices or are the result of the observation of the physical world, so rises significant security concerns. This article proposes a novel opportunistic flexible secure store and forward proxy for M2M networks and its mapping to asynchronous protocols that guarantees data confidentiality