Abstract: The natural radiative atmospheric environment is composed of secondary cosmic rays produced when primary cosmic rays hit the atmosphere. Understanding atmospheric radiations and their dynamics is essential for evaluating single event effects, so that radiation risks in aviation and the space environment (space weather) can be assessed. In this article, we present an atmospheric radiation model, named ATMORAD (Atmospheric Radiation), which is based on GEANT4 simulations of extensive air showers according to primary spectra that depend only on the solar modulation potential (force-field approximation). Based on neutron spectrometry, solar modulation potential can be deduced using neutron spectrometer measurements and ATMORAD. Some comparisons between our methodology and standard approaches or measurements are also discussed. This work demonstrates the potential for using simulations of extensive air showers and neutron spectroscopy to monitor solar activity.

Abstract: The amount of energy that organisms can allocate to self-maintenance and/or reproduction largely depends on their foraging strategies. Because of corticosterone (CORT) involvement in the control of energy metabolism, food intake and locomotor activity, recent studies have sought to demonstrate the role of this hormone in foraging decisions and performance. Moreover, considerable recent advances in animal-attached loggers now allow the study of behaviour in free-living animals. In order to assess the effects of CORT administration on the foraging behaviour of free-living Adelie Penguins Pygoscelis adeliae, we studied a group with CORT implants and a control group without CORT implants, by attaching time-depth recorders to the two groups and monitoring them throughout up to seven consecutive foraging trips during the guard stage (in Adelie Land, Antarctica). We found that foraging trips duration was similar between both groups. Dive durations, time spent at the bottom phase of dives, and the number of undulations per dive of CORT-implanted birds were all significantly higher than those of controls. However, CORT-implanted birds performed fewer dives overall (ca. 4,400) than controls (ca. 6,250) and spent many (13 and 6 times for penguins #3 and #4, respectively) long periods (>3 h) without diving. The low foraging effort and long resting periods support the view that CORT-implanted birds probably gained less energy than did the control birds. CORT treatment appears then to result in redirecting bird behaviour from costly activity (i.e. reproduction) to a behaviour promoting the preservation of energy reserves. Future studies are therefore needed to assess body condition and reproductive success of CORT-manipulated birds in parallel with the recording of their diving performances.

Abstract: During the 2005-06 Austral Summer, we carried out a joint observational campaign in the area of the David Glacier, South Victoria Land, with the aim of collecting simultaneous time series of geodetic and seismological data. We installed 7 temporary seismographic stations on rock outcrops surrounding the glacier and 3 temporary geodetic stations both on flowing ice and on rock. The seismic network registered a significant low-energy seismic activity, principally originated by ice creeping and basal stress at the interface between the ice and the bedrock. The geodetic stations allowed us to survey the glacier kinematics forced by the Ross Sea tides, and to infer the grounding line location. Here we show some details about data analysis and preliminary results.

Abstract: Cherry leaf roll virus (CLRV) is a well-known virus belonging to the genus Nepovirus, but unlike most members of this genus, it is not known to be transmitted by nematodes but only through seeds and pollen. Since its first description in 1955 on Prunus avium L. in England (1), CLRV has been shown to have a worldwide distribution and a wide natural host range. During a survey of plant viruses in the French sub-Antarctic islands, samples from nasturtium plants (Tropaeolum majus), an introduced plant species, showing symptoms of leaf mosaic, deformation, and veinal necrosis were collected on Amsterdam Island. Upon mechanical transmission with sap extracts, necrotic ringspot and oak-leaf symptoms typical of Nepovirus infection were observed on the leaves of inoculated Nicotiana clevelandii and N. tabacum plants. Inoculation of healthy nasturtium plants resulted in mosaic and pin-point necrosis symptoms. Electron microscopy on negatively stained sap extracts revealed the presence of icosahedral virions, 28 to ...

Abstract: The three Arctic Calanus species, C. finmarchicus (Gunnerus, 1765), C. glacialis (Jaschov, 1955), and C. hyperboreus, are the most important herbivores in Arctic seas in terms of species biomass. They play a key role in the lipid-based energy flux in the Arctic, converting low-energy carbohydrates and proteins in ice algae and phytoplankton into high-energy wax esters. In this paper we review the over-wintering strategy, seasonal migration, stage development, life span, feeding strategy, body size, lipid biochemistry and the geographic distribution of the three dominant Calanus species in Arctic waters. We then relate these parameters to other biotic and abiotic factors, such as the timing of the Arctic phytoplankton and ice algae bloom, sea ice cover and climate variability. We also present new data on fatty acid and fatty alcohol content in the three Calanus species in addition to reviewing the available literature on these topics. These data are analysed for species homogeneity and geographic grouping. The dominance of diatom fatty acid trophic markers in the lipids of Calanus underpins the importance of diatoms as Arctic primary producers, even if dinoflagellates and Phaeocystis pouchetii can also be important food sources for the calanoid copepods. We conclude that the Arctic Calanus species are herbivores, engineered to feed on the Arctic bloom, and that the timing of the bloom is the most important factor in determining the life strategies of the individual species.