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

Finite energy spin fluctuation as a pairing glue in systems with coexisting electron and hole bands

We study, within the fluctuation exchange approximation, the spin-fluctuation-mediated superconductivity in Hubbard-type models possessing electron and hole bands, and compare them with a model on a square lattice with a large Fermi surface. In the square lattice model, superconductivity is more enhanced for better nesting for a fixed band filling. By contrast, in the models with electron and hole bands, superconductivity is optimized when the Fermi surface nesting is degraded to some extent, where finite energy spin fluctuation around the nesting vector develops. The difference lies in the robustness of the nesting vector, namely, in models with electron and hole bands, the wave vector at which the spin susceptibility is maximized is fixed even when the nesting is degraded, whereas when the Fermi surface is large, the nesting vector varies with the deformation of the Fermi surface. We also discuss the possibility of realizing in actual materials the bilayer Hubbard model, which is a simple model with electron and hole bands, and is expected to have a very high T_c

Nesting, spin-fluctuations, and odd-gap superconductivity in NaxCoO2 yH2O

We have calculated the one-electron susceptibility of hydrated NaxCoO2 and find strong nesting nearly commensurate with a 2X2 superstructure. The nesting involves about 70% of all electrons at the Fermi level and is robust with respect to doping. This nesting creates a tendency to a charge density wave compatible with the charge order often seen at x approx 0.5, which is usually ascribed to electrostatic repulsion of Na ions. In the spin channel, it gives rise to strong spin-fluctuations, which should be important for superconductivity. The superconducting state most compatible with this nesting structure is an odd-gap triplet s-wave state.Comment: 4 figure

Nesting Success of Kemp’s Ridley Sea Turtles, Lepidochelys kempi, at Rancho Nuevo, Tamaulipas, Mexico, 1982–2004

The Kemp’s ridley sea turtle, Lepidochelys kempi, was on the edge of extinction owing to a combination of intense egg harvesting and incidental capture in commercial fishing trawls. Results from a cooperative conservation strategy initiated in 1978 between Mexico and the United States to protect and restore the Kemp’s ridley turtle at the main nesting beach at Rancho Nuevo, Tamaulipas, Mexico are assessed. This strategy appears to be working as there are signs that the species is starting to make a recovery. Recovery indicators include: 1) increased numbers of nesting turtles, 2) increased numbers of 100+ turtle nesting aggregations (arribadas), 3) an expanding nesting season now extending from March to August, and 4) significant nighttime nesting since 2003. The population low point at Rancho Nuevo was in 1985 (706 nests) and the population began to significantly increase in 1997 (1,514 nests), growing to over 4,000 nests in 2004. The size and numbers of arribadas have increased each year since 1983 but have yet to exceed the 1,000+ mark; most arribadas are still 200–800+ turtles

Trap-Nest Design for Small Trap-nesting Hymenoptera

(excerpt) Many solitary bees and wasps construct brood cells in pre-existing natural cavities such as beetle borings or in excavations of pithy stems and twigs like Sambucus and Juglans. Artificial nesting materials are also acceptable and provide a convenient approach to study nest architecture, nesting activity, provisions and parasites. Arti- ficial nesting materials have included bamboo, glass tubes, plastic straws, cuttings of twigs and stems, and trap-nests. However, use of many of these materials have significant drawbacks

Discriminating between nesting and non-nesting habitat in a vulnerable bird species: Implications for behavioural ecology

Nowadays, partitioning amongst nesting and non-nesting habitats is not much studied. Here, I investigate whether or not the turtle dove (Streptopelia turtur) nesting habitats overlap with those used for other purposes in a North African agroforestry system. A total of 33 nest points and 33 turtle dove presence points were considered. The study, conducted in May to June 2017, attempted to determine the factors that may play a role in discriminating between the nesting habitats and non-nesting habitats. I used a linear discriminant analysis (LDA) to test the relevance of proximity of food resources, forest edge and human presence variables in the distribution of the species. The results show substantial segregation in the habitats selected for nesting and those selected for other uses [average distance was 1129.69 ± 169.40 m (n = 66) with a maximum of 1518.6 m and a minimum of 617.72 m], with selection depending primarily on the proximity to forest edge and feeding areas. I discuss these findings and their implications on behavioural ecology and future researches of this vulnerable species. I suggest guidelines for future studies that will seek to better understand the behavioural dynamics of turtle doves in the Mediterranean agroforestry systems. This can only be done when disturbance covariates, such as: (i) forest logging, (ii) cereal harvesting and (iii) hunting and predation pressures, were imperatively taken into account

"Nested and Overlapping Regimes in the Transatlantic Banana Trade Dispute"

The decade long trans-Atlantic banana dispute was not a traditional trade conflict stemming from antagonistic producers’ interests. Instead, this article argues that the banana dispute is one of the most complex illustrations of the legal and political difficulties created by the nesting and overlapping of international institutions and commitments. The contested Europe-wide banana policy was an artifact of nesting--the fruit of efforts to reconcile the single market with Lomé obligations which then ran afoul of WTO rules. Using counter-factual analysis, this article explores how the nesting of international commitments contributed to creating the dispute, provided forum shopping opportunities which themselves complicated the options of decisionmakers, and hindered resolution of what would otherwise be a pretty straightforward trade dispute. We then draw out implications from this case for the EU, an institution increasingly nested within multilateral mechanisms, and for the issue of the nesting of international institutions in general

Strain effects on electronic structure of the iron selenide superconductor

The influence of various strains on crystal and electronic structures of superconducting FeSe has been studied ab initio. We consider changes in the Fermi surface nesting with a vector Q=(0.5,0.5)*(2\pi /a) as crucial for rising superconductivity (SC) mediated by spin-fluctuations (SF). Our results indicate that the c-axis strained FeSe exhibits the most imperfect nesting, which enhances SF and, hence, also SC. In turn, the ab-plane compressive strain slightly weakens this} nesting while the tensile strain destroys it completely. These findings are consistent with reported earlier experimental dependencies of superconducting transition temperatures on strain in FeSe thin films