Temperatura promedio de la superficie del mar frente a la costa peruana, periodo 1928-1969

El área considerada en el presente estudio es una pequeña porción costera del Pacífico Tropical Oriental, que se extiende entre las latitudes de 1°S-20°S y entre la costa y la longitud de 86°W. En la descripción empleamos el término de zona norte para referirnos a la parte situada al norte de los 6°S. Cuando decimos aguas oceánicas nos referimos a las aguas del océano abierto. Cuando hablamos de estaciones del año nos referimos a las estaciones del Hemisferio Sur. Las temperaturas promedio de la superficie del mar corresponden a observaciones realizadas en el período 1928-1969 (que viene a representar algo más de 4 décadas), y, por la densidad de las observaciones, son más representativas de las 4 estaciones del año pertenecen a: febrero, abril, setiembre y noviembre.

An experimental study of discharge partitioning and flow structure at symmetrical bifurcations

Recent research has examined the factors controlling the geometrical configuration of bifurcations, determined the range of stability conditions for a number of bifurcation types and assessed the impact of perturbations on bifurcation evolution. However, the flow division process and the parameters that influence flow and sediment partitioning are still poorly characterized. To identify and isolate these parameters, three-dimensional velocities were measured at 11 cross-sections in a fixed-walled experimental bifurcation. Water surface gradients were controlled, and systematically varied, using a weir in each distributary. As may be expected, the steepest distributary conveyed the most discharge ( was dominant) while the mildest distributary conveyed the least discharge ( was subordinate). A zone of water surface super-elevation was co-located with the bifurcation in symmetric cases or displaced into the subordinate branch in asymmetric cases. Downstream of a relatively acute-angled bifurcation, primary velocity cores were near to the water surface and against the inner banks, with near-bed zones of lower primary velocity at the outer banks. Downstream of an obtuse-angled bifurcation, velocity cores were initially at the outer banks, with near-bed zones of lower velocities at the inner banks, but patterns soon reverted to match the acute-angled case. A single secondary flow cell was generated in each distributary, with water flowing inwards at the water surface and outwards at the bed. Circulation was relatively enhanced within the subordinate branch, which may help explain why subordinate distributaries remain open, may play a role in determining the size of commonly-observed topographic features, and may thus exert some control on the stability of asymmetric bifurcations. Further, because larger values of circulation result from larger gradient disadvantages, the length of confluence-diffluence units in braided rivers or between diffluences within delta distributary networks may vary depending upon flow structures inherited from upstream and whether, and how, they are fed by dominant or subordinate distributaries. Copyright (C) 2011 John Wiley & Sons, Ltd.

Contributions to the knowledge of Banasa Stål (Hemiptera, Heteroptera, Pentatomidae): Banasa chaca Thomas

Contributions to the knowledge of Banasa Stål (Hemiptera, Heteroptera, Pentatomidae): Banasa chaca Thomas. The male of Banasa chaca Thomas is described with emphasis on external and internal genitalia and the female internal genitalia is described. Banasa chaca is newly recorded from Buenos Aires Province (Argentina).

Pineus boerneri Annand, 1928 (Hemiptera, Adelgidae) - a new species to Brazil: morphology of eggs, nymphs and adults

Pineus boerneri Annand, 1928 (Hemiptera, Adelgidae) _ a new species to Brazil: morphology of eggs, nymphs and adults. Pineus boerneri represents the first Adelgidae species recorded in Brazil. This aphid species forms extensive colonies on branches and trunk of Pinus spp., with apterous oviparous females, eggs and nymphs covered with white wax. The aim of this research is to study the morphology of eggs, nymphs, and adults to provide useful data for species identification in order to solve taxonomic issues. The study was based on morphometric data and optical and scanning electron microscopy images. First instar nymphs are active and can be easily distinguished from the others by their elongate minute yellowish body; well developed legs bearing a pair of sensorial setae at the apex of the second tarsomere; and antenna with three segments with a large rhinarium and distinct apical setae on the last segment. From the second to the fourth instar, nymphs are sessile, with round red body; they loose the third antennal segment and its sensorial structures, as well as the setae on the second tarsomere. The oviparous female is reddish-brown, with round body with about 0.76 mm diameter; legs reduced; antennae one-segmented; ovipositor distinct; numerous wax glands are present, mainly on the head. Accurate characterization of the species and distinction of the nymphal instars of P. boerneri were made possible by canonical analysis of morphometric data and morphological characters.

Helsinki 19.12.1928

Kirje