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In this paper, we study the dynamics of a quantum two-mesh LC circuit with discrete charge subject to rapidly oscillating voltage sources. A time-independent effective Hamiltonian for this system is derived in a high-frequency series expansion upto ω − 2 whose dominant behavior indicates the possibility of observing two physical phenomena: first, the controlled manipulation and suppression of the mesh currents by setting specific values of the voltage source amplitudes and, second, the onset of a DC regime (in the single–mesh case) which could be inferred by interpreting the quasi-degenerate quantum states. [ABSTRACT FROM AUTHOR]

Oceanic island ecosystems favour the appearance of novel interactions as a consequence of their depauperate and disharmonic flora and fauna. We investigated Echium simplex, endemic to the Anaga Biosphere Reserve in NE Tenerife, Canary Islands, belongs to the Canarian bird–flower element.Along two flowering seasons, we studied the breeding system of E. simplex, identified the floral visitors and compared the pollination effectiveness of different animal guilds (insects versus vertebrates) by means of selective exclosures.E. simplex is self‐compatible but selfing significantly reduced fruit set. The flowers were visited by five bird species (mostly Phylloscopus canariensis and Serinus canarius, but also Cyanistes teneriffae, Sylvia atricapilla and Sylvia melanocephala), a lizard species (Gallotia galloti) and over a hundred insect species (mainly hymenopterans and coleopterans). Flying insects increased fruit set whereas small flower dwellers (mostly beetles) decreased both fruit and seed set. Vertebrates had a negligible effect on reproductive success.We conclude that although the floral resources provided by E. simplex may be important to some vertebrate species, these do not appear to contribute to increase fitness of the plant, which was more dependent upon flying insects for fruit and seed set. We additionally found that plant reproductive structures are heavily damaged by feral goats, which threaten the maintenance of this Canarian endemic species. [ABSTRACT FROM AUTHOR]

We consider the semiclassical model of an extended tight-binding Hamiltonian comprising nearest- and next-to-nearest-neighbor interactions for a charged particle hopping in a lattice in the presence of a static arbitrary field and a rapidly oscillating uniform field. The application of Kapitza's method yields a time-independent effective Hamiltonian with long-range hopping elements that depend on the external static and oscillating fields. Our calculations show that the semiclassical approximation is quite reliable as it yields, for a homogeneous oscillating field, the same effective hopping elements as those derived within the quantum approach. Besides, by controlling the oscillating field, we can engineer the interactions so as to suppress the otherwise dominant interactions (nearest neighbors) and leave as observable effects those due to the otherwise remanent interactions (distant neighbors). [ABSTRACT FROM AUTHOR]

Three multiresistant clinical isolates of Pseudomonas aeruginosa were evaluated, by the chequerboard and the killing curve methods, for in-vitro synergy between cephalosporins and aminoglycosides. The killing-curve method was standardized to give results comparable with those obtained with the chequerboard test (FIC index). This was achieved with combinations showing synergy by chequerboard (FIC less than or equal to 0.75) by using in the killing curves subinhibitory concentrations: half the MIC in single antibiotic assay and one eighth the MIC in the combinations. For combinations that showed indifference by chequerboard (FIC = 1) half the MIC was used for antibiotics alone and in combination. For the antagonistic combinations by chequerboard (FIC greater than 2) concentrations equal to the MIC were used with single antibiotics and combinations in the killing curve experiments. Prediction of killing curve results could then be obtained with the FIC index. The killing curve results could not be explained by pH changes or inactivation of the antibiotics. [ABSTRACT FROM AUTHOR]

Populations of feral (not owned by humans) and domestic cats F elis catus coexist in most inhabited islands, and they have similar impacts on native species. Feral cats are generally believed to vary their diet according to prey availability; however, no previous studies of diet have tested this hypothesis on insular ecosystems with a limited range of available prey. Because domestic cats kill prey independently of hunger, the spatial extent of their impact on wildlife will be influenced by home-range size. In this study, we combined dietary information with cat movements to assess the impacts of feral and domestic cats on island biodiversity. We quantified the diet of cats from scat samples collected across one year and tested whether diet varies by season. The abundance of main prey categories was also estimated to document seasonal variation in prey availability for cats. Finally, we tracked domestic cats by global positioning system units in all four seasons to examine whether home-range patterns varied seasonally. The diet of cats constituted three prey groups (rodents, birds and invertebrates), and the seasonal variation in consumption of each taxon matched the seasonal variation in prey availability, thus supporting the generalist behaviour of cats on oceanic islands. Roaming behaviour varied among individuals and across seasons, but could not be explained by availability of prey. Unconfined cats had larger home-ranges than confined cats, but most domestic cats strayed <1 km from home. Thus, confinement of domestic cats might reduce the spatial extent of cat impact on native prey populations on oceanic islands. [ABSTRACT FROM AUTHOR]

In this paper, we consider a quantum-mechanical LC circuit connected to a peri-odic source and with elastic capacitor. In the limit of negligible inductor energy, we present explicitly an exact solution for the wave function and spectrum of the spring-capacitor-source system. Considering the inductor energy as a perturbative term, the time-dependent probability amplitudes for the complete system are derived. We show that the mechanical degrees of freedom lead a suppression of the capacitor's charg-ing/discharging process. Finally, we show the existence of a class of memristive compo-nent due to charge discreteness. [ABSTRACT FROM AUTHOR]

In this paper, we present results on germination patterns of the seed dispersal system of an endemic Macaronesian plant ( Rubia fruticosa). Seeds from this plant are mainly dispersed by endemic lizards and native warblers; therefore, we included three different treatments: control seeds, seeds extracted from lizards and seeds found in warbler droppings. Seeds from the same pool of every treatment were germinated in two different seasons, one in autumn, coinciding with the arrival of the first rains, and another in spring, coinciding with the arrival of the dry season. A clear differential pattern of germination success was observed between the two seasons. Seeds planted in autumn achieved a higher percentage of germination than those sown in spring in all treatments. The great robustness of these results seems to indicate that germination timing is strongly selected in R. fruticosa and this evolutionary trend probably extends to other vascular plants growing in xeric coastal environments of the Macaronesian islands. [ABSTRACT FROM AUTHOR]

1. The ecological effects and distribution of 13 invasive non-native mammal species on the Canary Islands are reviewed. 2. Six species, representing six different taxonomic orders, are widely distributed and live on all seven main islands of the Canarian Archipelago: Felis catus, Capra hircus, Rattus rattus, Rattus norvegicus, Mus domesticus and Oryctolagus cuniculus. Atelerix algirus is found on four islands while six further species are present on only one island: Crocidura russula, Suncus etruscus, Rousettus egyptiacus, Ovis gmelini, Ammotragus lervia and Atlantoxerus getulus. 3. Five species have an omnivorous diet, four are herbivorous, two insectivorous, one frugivorous and one carnivorous. The ecological effects and damage caused by these species in the natural habitats of the Canaries are similar to those in other insular regions. To our knowledge, the effects of two species, A. lervia (herbivorous) and A. getulus (omnivorous), are as yet unreported for other insular environments. 4. Two of the most pernicious effects caused by invasive non-native mammal species in the Canaries consist of predation by feral cats of the three giant lizard species present in the western islands, but especially Gallotia gomerana, which is now on the verge of extinction; and the damage that the four species of herbivores cause to the endemic flora of the archipelago. [ABSTRACT FROM AUTHOR]

Summary Indirect seed dispersal in the system Lycium intricatum (Solanaceae)–lizards (Gallotia atlantica) –shrikes (Lanius excubitor) was studied in Alegranza, a xerophytic small island of the Canarian archipelago. A total of 835 seeds (224 obtained from lizard droppings and 611 from shrike pellets) was found by analysing 123 droppings and 146 pellets. Lycium fruit remains (including seeds) were observed in 31.7% of the lizard droppings and 50% of the shrike pellets. As would be expected for legitimate seed dispersers, external seed damage produced by each species was negligible. Lycium seeds were significantly matched with the presence of lizard remains in shrike pellets. Seeds in shrike pellets have come from fruit consumed by lizards that have been predated by the shrikes, and not directly from bird frugivory. Seeds from shrike pellets showed significantly higher germination rates than those from uneaten fruits and lizard droppings. It seems probable that different treatments in the guts of each species and retention time are two main factors influencing the germination process. While gut pass time in G. atlantica has been estimated to be 2.42 days on average, the retention time of a seed inside a shrike gizzard is much shorter (45–55 min). This is a new case of the scarcely known phenomenon of indirect seed dispersal, which seems to acquire a relatively important role in small islands where the animal–plant interaction is very intense and all the elements of the system are native. [ABSTRACT FROM AUTHOR]

This paper presents the first data on the diet of the Raven Corvus corax in the Canary Islands, based on analysis of 2315 pellets collected from all of the islands and islets in the archipelago. The Ravens on three groups of island showed differences in diet, but in all cases the diet was clearly omnivorous, both in its qualitative and quantitative composition. It is evident that a broadening of the Raven's trophic niche has occurred in comparison with those living in continental areas. While the diet has a strong plant component on the wetter islands (frequency of occurrence > 87%), an appreciable animal component in the diet (principally vertebrates) is more frequent on the drier islands of the archipelago (frequency of occurrence > 96%). The composition of the plant component of the diet varied markedly from one island to another. Remains of refuse are more commonly found in the Raven's diet on the central and western islands. We concluded that while the animal diet is essential from the bioenergetic point of view, the vegetation diet is only a complementary food source. The Raven plays an important role in seed dispersal among the different habitats within each island. [ABSTRACT FROM AUTHOR]