Hawksbill (Eretmochelys imbricata) and Green Turtle (Chelonia mydas) Nesting and Beach Selection at Príncipe Island, West Africa

Hawksbills (Eretmochelys imbricata) and green turtles (Chelonia mydas) are the predominant nesting sea turtle species on the beaches of Príncipe Island in the Gulf of Guinea. The extent of nesting has been largely unknown, but such information is essential for management and conservation. Our study is the first island-wide nesting assessment. Results from the survey, conducted from 1 December 2009 to 18 January 2010 (during peak nesting season), show that the potential suitable nesting area (10 km) is scattered around the island’s 50 beaches. Sea turtles nested on 32 of the beaches (hawksbills, 20; green turtles, 28) and used 7.5 km of the suitable nesting habitat (hawksbills, 5.8 km; green turtles, 7.0 km). We estimated that 101 (95% CI = 86–118) clutches were deposited by 17-29 hawksbills and 1088 (95% CI = 999–1245) clutches were deposited by 166-429 green turtles on Príncipe from November 2009 to February 2010 (nesting season). Long-term green turtle nest count data collected from 2007/08 to 2015/16 suggest a positive trend. Analyses of clutch densities in relation to beach characteristics suggested that both species preferred areas where human presence is lower, which coincided with the most sheltered areas. These findings should be used to inform coastal planning and minimize impacts on nesting beaches, as Príncipe is currently targeted for tourism development. Overall, results highlight that Príncipe beaches are very important for the conservation of West African hawksbill and green turtle populations.info:eu-repo/semantics/publishedVersio

4,5-bis(benzoylsulfanyl)-1,3-dithiol-2-one

Peer reviewedPublisher PD

Exponential behavior of the interlayer exchange coupling across non-magnetic metallic superlattices

It is shown that the coupling between magnetic layers separated by non-magnetic metallic superlattices can decay exponentially as a function of the spacer thickness $N$, as opposed to the usual $N^{-2}$ decay. This effect is due to the lack of constructive contributions to the coupling from extended states across the spacer. The exponential behavior is obtained by properly choosing the distinct metals and the superlattice unit cell composition.Comment: To appear in Phys. Rev.

Temperature effect on (2+1) experimental Kardar-Parisi-Zhang growth

We report on the effect of substrate temperature (T) on both local structure and long-wavelength fluctuations of polycrystalline CdTe thin films deposited on Si(001). A strong T-dependent mound evolution is observed and explained in terms of the energy barrier to inter-grain diffusion at grain boundaries, as corroborated by Monte Carlo simulations. This leads to transitions from uncorrelated growth to a crossover from random-to-correlated growth and transient anomalous scaling as T increases. Due to these finite-time effects, we were not able to determine the universality class of the system through the critical exponents. Nevertheless, we demonstrate that this can be circumvented by analyzing height, roughness and maximal height distributions, which allow us to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang (KPZ) equation in a broad range of T. More important, one finds positive (negative) velocity excess in the growth at low (high) T, indicating that it is possible to control the KPZ non-linearity by adjusting the temperature.Comment: 6 pages, 5 figure

Qualitative analysis of a scalar-tensor theory with exponential potential

A qualitative analysis of a scalar-tensor cosmological model, with an exponential potential for the scalar field, is performed. The phase diagram for the flat case is constructed. It is shown that solutions with an initial and final inflationary behaviour appear. The conditions for which the scenario favored by supernova type Ia observations becomes an attractor in the space of the solutions are established.Comment: Latex file, 9 pages, 1 figur