Energy estimation of cosmic rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30-80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy-corrected for geometrical effects-is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.

Measurement of the radiation energy in the radio signal of extensive air showers as a universal estimator of cosmic-ray energy.

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 +/- 0.7 (stat) +/- 6.7 (syst) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principles calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.

Granulometry, geochemistry, amino acids, radiocarbon ages and paleomagnetics of samples from Heidemann Valley

A Pliocene (2.6-3.5 Ma) age is determined from glacial sediments studied in a 20m long, 4 m deep trench excavated in Heidemann Valley, Vestfold Hills, East Antarctica. The age determination is based on a combined study of amino acid racemization, diatoms, foraminifera, and magnetic polarity, and supports earlier estimates of the age of the sedimentary section; all are beyond 14C range. Four till units are recognized and documented, and 16 subunits are identified. All are ascribed to deposition during a Late Pliocene glaciation that was probably the last time the entire Vestfold Hills was covered by an enlarged East Antarctic Ice Sheet (EAIS). Evidence for other more recent glacial events of the 'Vestfold Glaciation' may have been due to lateral expansion of the Sorsdal Glacier and limited expansion of the icesheet margin during the Last Glacial Maximum rather than a major expansion of the EAIS. The deposit appears to correlate with a marine deposition event recorded in Ocean Drilling Program Site 1166 in Prydz Bay, possibly with the Bardin Bluffs Formation of the Prince Charles Mountains and with part of the time represented in the ANDRILL AND-1B core in the Ross Sea.

Micropaleontological investigation of sediment core Kronsmoor

Benthic foraminiferal and calcareous nannofossil assemblages, as well as stable isotope data from the Campanian/Maastrichtian boundary interval (~71.4 to ~70.7 Ma) of the Kronsmoor section (North German Basin), were investigated in order to characterize changes in surface-water productivity and oxygen content at the seafloor and their link to climatic and paleoceanographic changes. A nutrient index based on calcareous nannofossils is derived for the high-latitude, epicontinental North German Basin, reflecting changes in surface-water productivity. Oxygen isotopes of well-preserved planktic foraminiferal specimens of Heterohelix globulosa reflect warmer surface-water temperatures in the lower part of the studied succession and a cooling of up to 2°C (0.5 per mil) in the upper part (after 71.1 Ma). For the lower and warmer part of the investigated succession, benthic foraminiferal assemblages and the calcareous nannofossils indicate well-oxygenated bottom waters and low-surface water productivity. In contrast, the upper part of the succession is characterized by cooler conditions, lower oxygen content at the seafloor and increasing surface-water productivity. It is proposed that the cooling phase starting at 71.1 Ma was accompanied by increasing surface-water mixing caused by westerly winds. As a consequence of mixing, nutrients were advected from sub-surface waters into the mixed layer, resulting in increased surface-water productivity and enhanced organic matter flux to the seafloor. We hypothesize that global sea-level fall during the earliest Maastrichtian (~71.3 Ma), indicated by decreasing carbon isotope values, may have led to a weaker water mass exchange through narrower gateways between the Boreal Realm and the open North Atlantic and Tethys oceans. Both the weaker water mass exchange and enhanced surface-water productivity may have led to slightly less ventilated bottom waters of the upper part of the studied section. Our micro-paleontological and stable isotopic approach indicates short-term (<100 kyr) changes in oxygen consumption at the seafloor and surface-water productivity across the homogeneous Boreal White Chalk succession of the North German Basin.

Foraminiferal assemblage and statistical analysis of surface sediment samples from the Golfe d'Arguin, Mauritania

With the growing pressure of eutrophication in tropical regions, the Mauritian shelf provides a natural situation to understand the variability in mesotrophic assemblages. Site-specific dynamics occur throughout the 1200 m depth gradient. The shallow assemblages divide into three types of warm-water mesotrophic foraminiferal assemblages, which is not only a consequence of high primary productivity restricting light to the benthos but due to low pore water oxygenation, shelf geomorphology, and sediment partitioning. In the intermediate depth (approx. 500 m), the increase in foraminiferal diversity is due to the cold-water coral habitat providing a greater range of micro niches. Planktonic species characterise the lower bathyal zone, which emphasizes the reduced benthic carbonate production at depth. Although, due to the strong hydrodynamics within the Golf, planktonic species occur in notable abundances through out the whole depth gradient. Overall, this study can easily be compared to other tropical marine settings investigating the long-term effects of tropical eutrophication and the biogeographic distribution of carbonate producing organisms.

Biogenic opal and diatoms in surface sediments of the South Western Atlantic

Based on 66 surface sediment samples collected in the SW Atlantic Ocean between 27 and 50°S, this study presents an overview of the spatial distribution of biogenic opal and diatom concentrations, and diatom assemblages. Biogenic opal has highest values in the deepest, pelagic stations and decreases toward the slope. Diatoms closely follow the spatial trend of opal. Diatom assemblages reflect the present-day dominant hydrographical features. Antarctic diatoms are the main contributors to the preserved diatom community in core top sediments, with coastal planktonic and tropical/subtropical diatoms as secondary components. Dominance of Antarctic diatoms between 35 and 50°S in the pelagic realm mirrors the northward displacement of Antarctic-source water masses, characterized by high nutrient content and low salinity. Northward of ca. 35°S, the highest contribution of tropical/subtropical, pelagic diatoms, typical for nutrient-poor and high salinity waters, matches the main southward path of the Brazil Current. Mixing of Antarctic and tropical waters down up to 45°S is clearly illustrated by the diatom assemblage. Concentrations of biogenic opal and diatoms rather reflect the path of predominant water masses, but are less correlated with surface water productivity in the SW Atlantic.

Distribution of diatom species as abundance estimates from vertical multinet hauls from 150 m water depth in the Indian Ocean

During the Indian Ocean Expedition of R/V METEOR phytoplankton samples were taken with a multiple closing net (Multinet) at 103 stations. In this material the diatoms were investigated. In all 247 taxa could be identified which belong to 242 species and 5 varieties of formae of 80 genera. Of these 1 variety, 15 pecies, and 3 genera are newly described. New combinations were made for 18 species, and a number of old combinations was reinstated.

Dispersão de sementes por aves na galeria ripícola e matriz envolvente

As galerias ripícolas são habitats com uma grande disponibilidade de recursos alimentares e abrigo para a fauna, estando entre os habitats mais importantes e vulneráveis do mundo. São uma fonte de produção de frutos, o que atrai muitos animais, como as aves frugívoras, que são os principais dispersores de sementes na bacia do Mediterrâneo. O objetivo principal deste estudo foi estudar os padrões de dispersão de sementes por aves na interface galeria ripícola-matriz florestal envolvente (Montado). Foram marcadas com fluorescência plantas-mãe produtoras de frutos, e utilizadas armadilhas para sementes e transectos, para a recolha dos dejetos de aves onde, posteriormente, se detetaram as sementes dispersadas. Constatou-se que a dispersão de sementes e a abundância de plantas-mãe foi superior a distâncias mais próximas da ribeira, diminuindo à medida que esta distância aumenta. A espécie mais dispersada foi Smilax aspera e as espécies com sementes de menor dimensão, foram dispersadas a uma maior distância da planta-mãe, provavelmente devido a este tipo de sementes permanecerem mais tempo no trato intestinal das aves. Os resultados deste estudo apresentam algumas implicações para a colonização da matriz adjacente por plantas produtoras de frutos; ABSTRACT: Riparian galleries are habitats with a large availability food resources and shelter for animals, being among the most important and vulnerable habitats in the world. These zones are a great source of fruits attracting many animals, such as frugivorous birds, which are the main seed dispersers in the Mediterranean basin. The objective of this thesis is the study of seed dispersal patterns by birds, in the riparian gallery and in the surrounding forest matrix (Montado). Fruits of several plant species were used to collect bird droppings and detect fluorescent seeds in those droppings. Fruit abundance and seed dispersal were higher close to the stream, and decreased rapidly with an increase in distance from the stream. From all species, the most dispersed was Smilax aspera and species with smaller seed were found at a significantly larger distance from parents plants than species with large seeds. This can be explained by the fact that smaller seed stay longer in the intestinal tract of the birds. The results of this study present some implications for the colonization of freshly fruit plants from the riparian gallery into the adjacent matrix.

Measurement of the energy spectrum of cosmic rays above 10(18) eV using the Pierre Auger Observatory

We report a measurement of the flux of cosmic rays with unprecedented precision and Statistics using the Pierre Auger Observatory Based on fluorescence observations in coincidence with at least one Surface detector we derive a spectrum for energies above 10(18) eV We also update the previously published energy spectrum obtained with the surface detector array The two spectra are combined addressing the systematic uncertainties and, in particular. the influence of the energy resolution on the spectral shape The spectrum can be described by a broken power law E-gamma with index gamma = 3 3 below the ankle which is measured at log(10)(E-ankle/eV) = 18 6 Above the ankle the spectrum is described by a power law with index 2 6 followed by a flux suppression, above about log(10)(E/eV) = 19 5, detected with high statistical significance (C) 2010 Elsevier B V All rights reserved

Effects of the spermatozoa: oocyte ratio, water volume and water temperature on artificial fertilization and sperm activation of cascudo-preto

The objective of this study was to evaluate the effects of water volume and water temperature on the sperm motility duration and the number of spermatozoa, and the water volume on the fertilization rates of oocytes of Rhinelepis aspera. Experiments were carried out to evaluate the effect of semen dilutions (1.74×10-5, 1.74×10-4, 1.74×10-3, 1.74×10-2, 1.74×10-1 and 1.00 mL of sperm.mL-1 of water) and water temperature (5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 ºC) on spermatozoa motility duration. In addition, the effects of insemination dose (7×10³, 7×10(4), 7×10(5), 7×10(6) and 7×10(7) spermatozoa.oocyte-1) and water volume (1.0, 30.0, 60.0, 90.0 and 120.0 mL water.2.0 mL-1 oocytes) on the artificial fertilization rates of oocytes were evaluated. The longest sperm motility duration were observed for the semen dilution of 1.74×10-5 mL semen.mL-1 water and in water at 5 ºC. The highest fertilization rates were obtained for insemination doses between 7.00×10³ and 1.23×10(7) spermatozoa. oocyte-1 and water volume of 28.11 mL water.2.0 mL-1 oocytes.

Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers

To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accuracy by this correction. First, we operate a "beacon transmitter" which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA.