Energetic Particles Measured in and out of the Ecliptic Plane During the Last Gnevyshev Gap

Solar Physics - We analyzed the temporal variation of energetic particles measured by the Low Energy Telescope (LET), the Kiel Electron Telescope (KET), and the High Energy Telescope (HET)...     

A comparison of integrated and discrete depth sampling for monitoring toxic species of Dinophysis

Dinophysis acuminata and Dinophysis acuta produce lipophilic toxins that cause most shellfish harvesting closures in the Atlantic coastal waters of Europe. Dinophysis often exhibit patchy distributions and sampling with conventional methods may fail to detect them. A 6-month calibration study in 2006, plus an additional sampling in 2010 were carried out in Galicia to compare Dinophysis counts obtained from weekly high vertical resolution bottle samples with depth-integrated hose samples. Counts with these two methods were comparable at some depth-ranges, but hose maxima were over one order of magnitude lower under thin-layer scenarios. Estimates from hose samplers should be used with caution in programmes using a "Dinophysis index", either to trigger shellfish sampling or to establish precautionary harvesting closures. In general, hose samplers provide reliable information on the occurrence of Dinophysis except under extreme site-specific hydrodynamic conditions. This study adds new information about the heterogeneous, specific vertical distributions of two Dinophysis spp.     

Semi-Periodic Sequences and Extraneous Events in Earthquake Forecasting. II: Application,Forecasts for Japan and Venezuela

In order to analyze observed seismicity in central Japan and Venezuela, we applied a new method to identify semi-periodic sequences in the occurrence times of large earthquakes, which allows for the presence of multiple periodic sequences and/or events not belonging to any sequence in the time series. We also explored a scheme for diminishing the effects of a sharp cutoff magnitude threshold in selecting the events to analyze. A main four-event sequence with probability P _c  = 0.991 of not having occurred by chance was identified for earthquakes with M ≥ 8.0 in central Japan. Venezuela is divided, from West to East, into four regions; for each of these, the magnitude ranges and identified sequences are as follows. Region 1: M ≥ 6.0, a six-event sequence with P _c  = 0.923, and a four-event sequence with P _c  = 0.706. Region 2: M ≥ 5.6, a five-event sequence with P _c  = 0.942. Region 3: M ≥ 5.6, a four-event sequence with P _c  = 0.882. Region 4: M ≥ 6.0, a five-event sequence with P _c  = 0.891. Forecasts are made and evaluated for all identified sequences having four or more events and probabilities ≥0.5. The last event of all these sequences was satisfactorily aftcast by previous events. Whether the identified sequences do, in fact, correspond to physical processes resulting in semi-periodic seismicity is, of course, an open question; but the forecasts, properly used, may be useful as a factor in seismic hazard estimation.     

Semi-Periodic Sequences and Extraneous Events in Earthquake Forecasting: I. Theory and Method,Parkfield Application

We present a new method to identify semi-periodic sequences in the occurrence times of large earthquakes, which allows for the presence of multiple semi-periodic sequences and/or events not belonging to any identifiable sequence in the time series. The method, based on the analytic Fourier transform, yields estimates of the departure from periodicity of an observed sequence, and of the probability that the sequence is not due to chance. These estimates are used to make and to evaluate forecasts of future events belonging to each sequence. Numerous tests with synthetic catalogs show that the method is surprisingly capable of correctly identifying sequences, unidentifiable by eye, in complicated time series. Correct identification of a given sequence depends on the number of events it contains, on the sequence’s departure from periodicity, and, in some cases, on the choice of starting and ending times of the analyzed time window; as well as on the total number of events in the time series. Some particular data combinations may result in spectra where significant periods are obscured by large amplitudes artifacts of the transform, but artifacts can be usually recognized because they lack harmonics; thus, in most of these cases, true semi-periodic sequences may not be identified, but no false identifications will be made. A first example of an application of the method to real seismicity data is the analysis of the Parkfield event series. The analysis correctly aftcasts the September 2004 earthquake. Further applications to real data from Japan and Venezuela are shown in a companion paper.     

CCD and photon-counting photometric observations of asteroids carried out at Padova and Catania observatories

We present the results of observational campaigns of asteroids performed at Asiago Station of Padova Astronomical Observatory and at M.G. Fracastoro Station of Catania Astrophysical Observatory, as part of the large research programme on Solar System minor bodies undertaken since 1979 at the Physics and Astronomy Department of Catania University. Photometric observations of six Main-Belt asteroids (27 Euterpe, 173 Ino, 182 Elsa, 539 Pamina, 849 Ara, and 984 Gretia), one Hungaria (1727 Mette), and two Near-Earth Objects (3199 Nefertiti and 2004 UE) are reported. The first determination of the synodic rotational period of 2004 UE was obtained. For 182 Elsa and 1727 Mette the derived synodic period of 80.23±0.08 and , respectively, represents a significant improvement on the previously published values. For 182 Elsa the first determination of the H-G magnitude relation is also presented.     

Daily and annual cycle of CO2 concentration near the surface depending on boundary layer structure at a rural site in Spain

CO₂ in the rural atmosphere is related to respiration–photosynthesis processes, although the evolution of the low atmosphere is also a determinant factor. CO₂ concentrations were measured at surface and meteorological variables obtained from a radio acoustic sounding system sodar at a flat rural site during a 3-year campaign. Yearly and daily cycles of CO₂ were described. Maxima were observed in spring and autumn during the night. Wind speed and thermal structure of the lower atmosphere were analysed. Low level jets were observed during the night, their core proving lower in summer. Surface inversions observed with low winds reached up to 100 m. The turbulence layer which developed during the day extended up to 300–400 m and was capped by a stable layer. Median vertical wind speed reached 1 m s^?1 in super-adiabatic conditions in summer. Determination of decoupled low level jets proved difficult with the device used and corresponding concentrations were slightly higher than medians calculated with all the observations. The bulk Richardson number was calculated in the lower atmosphere and four intervals were considered: drainage, transitional, shear flows and unstable conditions. Median CO₂ concentrations were split according to these intervals. Higher values corresponded to drainage flow, which was associated to more stable conditions being less frequent and lower values to shear flow and unstable conditions, revealing a satisfactory link between the bulk Richardson number as a turbulence indicator in the low atmosphere and CO₂ surface concentrations.     

Study of terrestrial fossils in phyllosilicate-rich soils: Implication in the search for biosignatures on Mars

The search for biosignatures in the soil of Mars is a major objective of the planet exploration, but the detection of such structures is not straightforward due to the degradation of the organic material. In a previous work our group has analyzed the spectral reaction to thermal processing of biomineral carbonate samples including fresh and fossil shells. We found that two terrestrial fossil shells collected from clay deposits preserve their biomineral characteristics much better than coeval fossils not embedded in clay layers.In the present paper we extend our analysis to a set of fossils found in three different terrestrial clay deposits. Our results confirm that the level of degradation may be much lower than the standard values if fossils are surrounded by clay minerals. As a result these fossils have a spectroscopic response to thermal treatment which make them much more distinguishable from their abiotic counterparts than coeval fossils not collected from clay deposits. This result implies that the phyllosilicates regions recently discovered on Mars may represent very interesting environments that can provide conditions favorable to preserve evidence of biomarkers, and hence can be regarded as good candidate locations for their detection.     

A new jadeitite jade locality (Sierra del Convento, Cuba): first report and some petrological and archeological implications

A new jadeitite jade locality has been discovered in the serpentinite-matrix subduction mélange of the Sierra del Convento (eastern Cuba) in a context associated with tectonic blocks of garnet-epidote amphibolite, tonalitic–trondhjemitic epidote gneiss, and blueschist. The mineral assemblages of jadeitite jade and jadeite rocks are varied and include combinations of jadeite, omphacite, albite, paragonite, analcime, clinozoisite-epidote, apatite, phlogopite, phengite, chlorite, glaucophane, titanite, rutile, zircon, and quartz formed during various stages in their P–T evolution. Field relationships are obscure, but some samples made almost exclusively of jadeite show evidence of crystallization from fluid in veins. In one of these samples studied in detail jadeite shows complex textural and chemical characteristics (including oscillatory zoning) that denote growth in a changing chemical medium. It is proposed that interaction of an Al–Na rich fluid with ultramafic rocks produced Al–Na–Mg–Ca fluids of varying composition. Episodic infiltration of these fluids, as a result of episodic opening of the veins, developed oscillatory zoning by direct precipitation from fluid and after reaction of fluid with pre-existing jadeite. The latest infiltrating fluids were richer in Mg–Ca, favouring the formation of omphacite and Mg–Ca rich jadeite in open voids and the replacement of earlier jadeite by fine-grained omphacite + jadeite at 550–560°C. This new occurrence of jadeite in Cuba opens important perspectives for archeological studies of pre-Columbian jade artifacts in the Caribbean region.