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This article describes the basis and principles of high efficiency active radiators. First, the relation between power amplifiers and microstrip patch antennas is presented. Then, a high efficiency active patch [...]

Le régime alimentaire des adultes de gardons et de perches du lac de Pareloup a été mis en évidence par l'analyse de leurs contenus intestinaux (gardons) et stomacaux (perches) de janvier à juillet 1990. Les spectres alimentaires ont été établis grâce à l'indice de poids qui a permis de visualiser une hiérarchie des proies en fonction de la classe de taille et de la saison. Ces spectres montrent que les gardons de 100 à 209 mm ont une alimentation à base de détritus et de zooplancton alors que les individus plus âgés sont détritivores. II existe une variation saisonnière du régime des deux espèces : les détritus dominent l'alimentation du gardon en hiver; ils sont progressivement remplacés par le zooplancton (Cladocères) et, en quantité moindre, par les macroinvertébrés (Chironomidae) à partir de mars. Détritus et zooplancton (Copépodes) dominent le régime de la perche en hiver et sont remplacés plus ou moins rapidement suivant la taille des poissons par les macroinvertébrés (Chironomidae) et les Ostéichtyens (alevins de gardons). Le phytoplancton (Diatomophycées) est ingéré en grande quantité par les gardons, mais sa contribution pondérale est toujours faible; il est exclu du régime des perches. Les deux espèces se nourrissent activement pendant toute la période d'étude : les gardons de façon assez opportuniste, les perches de manière plus sélective.

In a system of deconfined quarks and gluons heavy quarkonium states are expected to be the subject of dissociation via static mechanisms such as colour screening or dynamic mechanisms such as gluon scatterings. This leads to a suppression of hidden charm states, such as J/?. On the other hand, statistical hadronization models predict an enhanced production of hidden charm states for sufficiently high charm densities. We present first preliminary STAR results on J/? production via the reconstruction of electron-positron decay pairs in p + p and Au + Au collisions at . The implications of our measurements to models that predict copious J/? production via statistical hadronization are discussed.

We present first measurements of the pseudorapidity and azimuth (η, φ) bin-size dependence of event-wise mean transverse-momentum 〈pt〉 fluctuations for Au–Au collisions at GeV. We invert that dependence to obtain pt autocorrelations on differences (ηΔ, φΔ) interpreted to represent velocity/temperature distributions on (η, φ). The general form of the autocorrelations suggests that the basic correlation mechanism is parton fragmentation. The autocorrelations vary rapidly with collision centrality, which suggests that fragmentation is strongly modified by a dissipative medium in the more central Au–Au collisions relative to peripheral or p–p collisions.

Grand canonical Monte Carlo simulations have been used to study the adsorption of homonuclear dimers on triangular and honeycomb two-dimensional lattices. Adsorption isotherms, adsorption energy, differential heat of adsorption, and configurational entropy were calculated for attractive and repulsive nearest-neighbor lateral interactions. In the second case (repulsive couplings) and low temperatures, we found two novel ordered phases in the adsorbate:  (1) low-coverage ordered phase (LCOP), with 2/5 (5/9) of the sites occupied for a triangular (honeycomb) lattice; (2) high-coverage ordered phase (HCOP), with 2/3 of the sites filled for both lattices. The locations of the ordered phases are not symmetrical around θ = 0.5; this is a consequence of the nonequivalence between vacancies and particles in the case of adsorption with multisite occupancy. The influence of the ordered structures on the thermodynamic quantities associated with the adsorbed monolayer has been analyzed and discussed in the context of the lattice−gas model.

The structural patterns and trophodynamics of the different fish species in the reef complex of Palancar-Chunchakaab, located in the South of Cozumel Island, Mexican Caribbean, were studied. A total of 166 species were identified for the whole reef complex. The analysis of 19,636 recorded and 2291 fish collected allowed the populations to be characterized in terms of diversity, distribution, abundance, dominant species and habitat-fish interactions. Using these parameters, three well defined reef-fish communities were described in relation to three zones: (1) Thalassia zone (THZ), (2) Lagoon (LA) and (3) Shelf-Edge Reef (SER). These communities included 64 species (39% of the total number) that were restricted to a single zone,. The remaining 61% consisted of migratory species that interacted between the defined zones (interdependence of habitat): (1) THZ-LA, (2) THZ-LA-SER, and (3) LA-SER. Diversity was highest in the rainy season in SER (H' n = 3.3). Analysis of distribution and frequency of 42 of the recorded species revealed that for 25%, life cycle and THZ-SER were closely related. The remaining 75% were more associated with SER or THZ and they used these habitats for feeding, breeding and/or protection. In THZ, > 70% of the total number of species were juveniles; in LA, 40% were preadults-adults; and in SER 80% were adults. The obvious interdependence between habitats suggested a distinct use of the resources by means of migration patterns. By decreasing the order of importance, the major diet types can be ranked as follows: (1) type I carnivores, mainly active by day, preying on small organisms such as crustaceans, polychaetes, mollusks, echinoderms; (2) type II carnivores, nocturnal species consuming larger crustaceans and fish; (3) strict piscivores species; (4) herbivores species; (5) planktivores species; (6) omnivores species; and (7) sessile invertebrate browsers. With the exception of SER, 14%-44% of the type II invertebrate feeders were restricted to the three defined habitats. Of the migratory species, the large invertebrate feeders were the dominant group (21%-41%). The present study suggests that the variation of species diversity patterns and trophic structure are associated with sequential habitat use according to the life cycle. This type of study allowed us to compare the diversity and trophic community of reef fish of the same system and to recognize the energetic interdependence that exists between the habitats.

Les préférences alimentaires des gardons du lac de Pareloup ont été mises en évidence par l'analyse de leurs contenus intestinaux de janvier à juillet 1990. Les spectres alimentaires ont été établis grâce à l'indice de poids qui a permis de visualiser une hiérarchie des proies en fonction de la classe de taille et de la saison. Ces spectres montrent que les gardons de 10 à 21 cm ont une alimentation à base de détritus et de zooplancton alors que les individus plus âgés sont détritivores. Il existe une variation saisonnière du régime des gardons : les détritus dominent en hiver ; ils sont progressivement remplacés par le zooplancton (Cladocères) et, en quantité moindre, par les macroinvertébrés (Chironomidae) à partir de mars. Le phytoplancton (Diatomophycées) est ingéré en grande quantité, mais sa contribution pondérale est toujours faible. Les gardons de Pareloup se nourrissent activement pendant toute la période d'étude et de façon assez opportuniste.

The analysis of perturbative quantities is a powerful tool to distinguish between different dark energy models and gravity theories degenerated at the background level. In this work, we generalize the integral solution of the matter density contrast for general relativity gravity [V. Sahni and A. Starobinsky, Int. J. Mod. Phys. D 15, 2105 (2006)., U. Alam, V. Sahni, and A. A. Starobinsky, Astrophys. J. 704, 1086 (2009).] to a wide class of modified gravity (MG) theories. To calculate this solution, it is necessary to have prior knowledge of the Hubble rate, the density parameter at the present epoch (Ωm0), and the functional form of the effective Newton's constant that characterizes the gravity theory. We estimate in a model-independent way the Hubble expansion rate by applying a nonparametric reconstruction method to model-independent cosmic chronometer data and high-z quasar data. In order to compare our generalized solution of the matter density contrast, using the nonparametric reconstruction of H(z) from observational data, with a purely theoretical one, we choose a parametrization of the screened modified gravity and the Ωm0 from WMAP-9 Collaborations. Finally, we calculate the growth index for the analyzed cases, finding very good agreement between theoretical values and the obtained ones using the approach presented in this work. [ABSTRACT FROM AUTHOR]

Since there is no known symmetry in nature that prevents a nonminimal coupling between the dark energy (DE) and cold dark matter (CDM) components, such a possibility constitutes an alternative to standard cosmology, with its theoretical and observational consequences being of great interest. In this paper, we propose a new null test on the standard evolution of the dark sector based on the time dependence of the ratio between the CDM and DE energy densities which, in the standard ΛCDM scenario, scales necessarily as a-3. We use the latest measurements of type Ia supernovae, cosmic chronometers and angular baryonic acoustic oscillations to reconstruct the expansion history using model-independent machine learning techniques, namely, the linear model formalism and Gaussian processes. We find that while the standard evolution is consistent with the data at 3σ level, some deviations from the ΛCDM model are found at low redshifts, which may be associated with the current tension between local and global determinations of H0. [ABSTRACT FROM AUTHOR]