Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling

Ground-based observations of dayside auroral forms and magnetic perturbations in the arctic sectors of Svalbard and Greenland, in combination with the high-resolution measurements of ionospheric ion drift and temperature by the EISCAT radar, are used to study temporal/spatial structures of cusp-type auroral forms in relation to convection. Large-scale patterns of equivalent convection in the dayside polar ionosphere are derived from the magnetic observations in Greenland and Svalbard. This information is used to estimate the ionospheric convection pattern in the vicinity of the cusp/cleft aurora. The reported observations, covering the period 0700-1130 UT, on January 11, 1993, are separated into four intervals according to the observed characteristics of the aurora and ionospheric convection. The morphology and intensity of the aurora are very different in quiet and disturbed intervals. A latitudinally narrow zone of intense and dynamical 630.0 nm emission equatorward of 75 degrees MLAT, was observed during periods of enhanced antisunward convection in the cusp region. This (type 1 cusp aurora) is considered to be the signature of plasma entry via magnetopause reconnection at low magnetopause latitudes, i.e. the low-latitude boundary layer (LLB I,). Another zone of weak 630.0 nm emission (type 2 cusp aurora) was observed to extend up to high latitudes (similar to 79 degrees MLAT) during relatively quiet magnetic conditions, when indications of reverse (sunward) convection was observed in the dayside polar cap. This is postulated to be a signature of merging between a northward directed IMF (B-z > 0) and the geomagnetic field poleward of the cusp. The coexistence of type 1 and 2 auroras was observed under intermediate circumstances. The optical observations from Svalbard and Greenland were also used to determine the temporal and spatial evolution of type 1 auroral forms, i.e. poleward-moving auroral events occurring in the vicinity of a rotational convection reversal in the early post-noon sector. Each event appeared as a local brightening at the equatorward boundary of the pre-existing type 1 cusp aurora, followed by poleward and eastward expansions of luminosity. The auroral events were associated with poleward-moving surges of enhanced ionospheric convection and F-layer ion temperature as observed by the EISCAT radar in Tromso. The EISCAT ion flow data in combination with the auroral observations show strong evidence for plasma flow across the open/closed field line boundary.

Statistical characterisation of the growth and spatial scales of the substorm onset arc

We present the first multi-event study of the spatial and temporal structuring of the aurora to provide statistical evidence of the near-Earth plasma instability which causes the substorm onset arc. Using data from ground-based auroral imagers, we study repeatable signatures of along-arc auroral beads, which are thought to represent the ionospheric projection of magnetospheric instability in the near-Earth plasma sheet. We show that the growth and spatial scales of these wave-like fluctuations are similar across multiple events, indicating that each sudden auroral brightening has a common explanation. We find statistically that growth rates for auroral beads peak at low wavenumber with the most unstable spatial scales mapping to an azimuthal wavelength λ≈1700 − 2500 km in the equatorial magnetosphere at around 9-12 RE. We compare growth rates and spatial scales with a range of theoretical predictions of magnetotail instabilities, including the cross-field current instability and the shear-flow ballooning instability. We conclude that, although the cross-field current instability can generate similar magnitude of growth rates, the range of unstable wavenumbers indicates that the shear-flow ballooning instability is the most likely explanation for our observations.

Temporal and spatial variability of surface fluxes over the ice edge zone in the northern Baltic Sea

Three land-fast ice stations (one of them was the Finnish research ice breaker Aranda) and the German research aircraft Falcon were applied to measure the turbulent and radiation fluxes over the ice edge zone in the northern Baltic Sea during the Baltic Air-Sea-Ice Study (BASIS) field experiment from 16 February to 6 March 1998. The temporal and spatial variability of the surface fluxes is discussed. Synoptic weather systems passed the experimental area in a rapid sequence and dominated the conditions (wind speed, airsurface temperature difference, cloud field) for the variability of the turbulent and radiation fluxes. At the ice stations, the largest upward sensible heat fluxes of about 100 Wm�2 were measured during the passage of a cold front when the air cooled faster (�5 K per hour) than the surface. The largest downward flux of about �200 Wm�2 occurred during warm air advection when the air temperature reached +10�C but the surface temperature remained at 0�C. Spatial variability of fluxes was observed from the small scale (scale of ice floes and open water spots) to the mesoscale (width of the ice edge zone). The degree of spatial variability depends on the synoptic situation: during melting conditions downward heat fluxes were the same over ice and open water, whereas during strong cold-air advection upward heat fluxes differed by more than 100 Wm�2. A remarkable amount of grey ice with intermediate surface temperature was observed. The ice in the Baltic Sea cannot be described by one ice type only.

Grain size and heavy minerals of the Late Quaternary eolian sediments from the Imbituba-Jaguaruna coast, Southern Brazil: Depositional controls linked to relative sea-level changes

The stratigraphic subdivision and correlation of dune deposits is difficult, especially when age datings are not available. A better understanding of the controls on texture and composition of eolian sands is necessary to interpret ancient eolian sediments. The Imbituba-Jaguaruna coastal zone (Southern Brazil, 28 degrees-29 degrees S) stands out due to its four well-preserved Late Pleistocene (eolian generation 1) to Holocene eolian units (eolian generations 2, 3, and 4). In this study, we evaluate the grain-size and heavy-mineral characteristics of the Imbituba-Jaguartma eolian units through statistical analysis of hundreds of sediment samples. Grain-size parameters and heavy-mineral content allow us to distinguish the Pleistocene from the Holocene units. The grain size displays a pattern of fining and better sorting from generation 1 (older) to 4 (younger), whereas the content of mechanically stable (dense and hard) heavy minerals decreases from eolian generation 1 to 4. The variation in grain size and heavy-mineral content records shifts in the origin and balance (input versus output) of eolian sediment supply attributable mainly to relative sea-level changes. Dunefields submitted to relative sea-level lowstand conditions (eolian generation 1) are characterized by lower accumulation rates and intense post-depositional dissection by fluvial incision. Low accumulation rates favor deflation in the eolian system, which promotes concentration of denser and stable heavy minerals (increase of ZTR index) as well as coarsening of eolian sands. Dissection involves the selective removal of finer sediments and less dense heavy minerals to the coastal source area. Under a high rate of relative sea-level rise and transgression (eolian generation 2), coastal erosion prevents deflation through high input of sediments to the coastal eolian source. This condition favors dunefield growth. Coastal erosion feeds sand from local sources to the eolian system. including sands from previous dunefields (eolian generation 1) and from drowned incised valleys. Therefore, dunefields corresponding to transgressive phases inherit the grain-size and heavy-mineral characteristics of previous dunefields, leading to selective enrichment of finer sands and lighter minerals. Eolian generations 3 and 4 developed during a regressive-progradational phase (Holocene relative sea level highstand). The high rate of sediment supply during the highstand phase prevents deflation. The lack of coastal erosion favors sediment supply from distal sources (fluvial sediments rich in unstable heavy minerals). Thus, dunefields of transgressive and highstand systems tracts may be distinguished from dunefields of the lowstand systems tract through high rates of accumulation (low deflation) in the former. The sediment source of the transgressive dunefields (high input of previously deposited coastal sands) differs from that of the highstand dunefields (high input of fluvial distal sands). Based on this case study, we propose a general framework for the relation between relative sea level, sediment supply and the texture and mineralogy of eolian sediments deposited in siliciclastic wet coastal zones similar to the Imbituba-Jaguaruna coast (C) 2009 Elsevier B.V. All rights reserved.

Prediction of the economic activity from the short and long-term interest rate differential: new evidences in Chile and the United States of America cases

The purpose of this work is to verify the stability of the relationship between real activity and interest rate spread. The test is based on Chen (1988) and Osorio and Galea (2006). The analysis is applied to Chile and the United States, from 1980 to 1999. In general, in both cases the relationship was statistically significant in early 80s, but a break point is found in both countries during that decades, suggesting that the relationship depends on the monetary rule follow by the Central Bank.

Terrain forms and spatial variability of soil properties in an area cultivatedwith citrus

A técnica de agricultura de precisão e a relação solo-paisagem permitem delimitar áreas para o manejo localizado, o que permite a aplicação localizada de insumos agrícolas e, consequentemente, pode contribuir para a preservação de recursos naturais. Portanto, o objetivo deste trabalho foi caracterizar a variabilidade espacial das propriedades químicas e do teor de argila, no contexto da relação solo-paisagem, em um Latossolo sob cultivo de citros. Amostras de solo foram coletadas na profundidade de 0,0-0,2 m, em uma área de 83,5 ha cultivada com citros, na forma de malha, com intervalos regulares de 50 m, com 129 pontos na forma de relevo côncava e 206 pontos na forma plana, totalizando 335 pontos. Os valores obtidos para as variáveis que expressam as propriedades químicas e para o teor de argila do solo foram submetidos à análise estatística descritiva e geoestatística com a modelagem de semivariogramas para a confecção de mapas de krigagem. Os valores de alcance e mapas de krigagem indicaram maiores variabilidades na forma de relevo côncava (segmento topo), quando comparada com a forma plana (segmentos meia encosta e encosta inferior). A identificação de diferentes formas de relevo mostrou-se eficiente no entendimento da variabilidade espacial das propriedades químicas e do teor de argila do solo sob cultivo de citros.

Effects of corn particle size and physical form of the diet on the gastrointestinal structures of broiler chickens

The objective of this experiment was to investigate the effects of different particle sizes, expressed as Geometric Mean Diameter (GMD) of corn (0.336mm, 0.585mm, 0.856mm and 1.12mm) of mash and pelleted broiler chicken diets on the weight of the gizzard, duodenum and jejunum+ileum; on the pH of the gizzard and small intestine and on the characteristics of the duodenal mucous layer (number and height of villi and crypt depth) in 42-day-old broilers. The physical form and the particle size of the diet had no significant effect on gizzard and intestine pH (p > 0.05). A greater gizzard weight was seen in the birds receiving pelleted diet and particle size of 0.336mm (p < 0.008). However, for the particle sizes of 0.856 and 1.12 mm, a greater weight was found in birds that received mash diet (p < 0.039 and p < 0.006, respectively). Also, gizzard weight was greater with increasing corn GMD independent of the physical form of the diet. In the mash diet, the increase in particle size promoted a quadratic response in the weight of duodenum and jejunum + ileum. The pelleted diet promoted a greater number of villi per transverse duodenum cut (p < 0.007) and greater crypt depth (p < 0.05). As the particle size increased, there was a linear increase of villus height and crypt depth in the duodenum, irrespective of the physical form of the diet.

Effects of meal size and proximal-distal segmentation on gastric activity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fecundity, body size and population dynamics of Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Annual, seasonal and spatial variation of abundance of the shrimp Artemesia longinaris (Decapoda : Penaeoidea) in south-eastern Brazil

The influence of several environmental factors oil the abundance and spatial-temporal distribution of the shrimp Artemesia longinaris were investigated from January 1998 to December 1999 in the Ubatuba region of São Paulo State, Brazil. Collections were performed monthly in the bays of Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV). Six sampling transects were estabilshed in each bay, four were parallel to the shore line, and two were next to the rocky shores. A commercial shrimp fishing boat equipped with two 'double-rig' nets was used. A total of 11,503 individuals was collected, including 1633 from UBM, 6344 from UBA and 3526 from MV the majority of the captured specimens came from the deeper areas (15 to 20 m) with high salinity (34 to 36 ppt). The highest abundance of A. longinaris in Ubatuba bay was recorded in areas where fine and very fine sand comprised more than 70% of the sediment. Moreover, the abundance of A. longinaris followed a seasonal trend, being higher during the summer, when intrusions of cold South Atlantic Coastal Waters (SACW) are frequent. Thus, type of sediment, temperature and salinity are determinant factors in the distribution of A. longinaris in the studied region.

Species composition and spatial distribution of a stream fish assemblage in the east coast of Brazil: comparison of two field study methodologies

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Seed dispersal and spatial distribution of Attalea geraensis (Arecaceae) in two remnants of Cerrado in Southeastern Brazil

The seed dispersal system of Attalea geraensis (Arecaceae), an acaulescent palm, was investigated during one year in two Cerrado fragments in the state of São Paulo, southeastern Brazil. A. geraensis had inflorescences and infrutescences throughout the year. Two scatter-hoarding rodents (the spiny rat, Clyomys bishopi and agoutis, Dasyptocta azarae) were identified as seed predators/dispersers, able to move seeds up to 30 in from the palms, although most of the fruits (57.5%) were dispersed less than 2 in. The removal rates were high and after 20 days, 97.2% of the fruits were removed. Fruit fate was not related to fruit mass, length and diameter. The application of Morisita's index showed a more clumped distribution of adults in the smaller fragment, probably because of the absence of agoutis. Higher seed removal by rodents in the large Cerrado remnant may decrease seed predation by beetles. (C) 2007 Elsevier Masson SAS. All rights reserved.

Density and Spatial Distribution of Buffy-tufted-ear Marmosets (Callithrix aurita) in a Continuous Atlantic Forest

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diet and Spatial Pattern of Foraging in Ectatomma opaciventre (Hymenoptera: Formicidae) in an Anthropic Area

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)