Search results for "Clima"
showing 10 items of 6069 documents
Resonant origin for density fluctuations deep within the Sun: helioseismology and magneto-gravity waves
2003
We analyze helioseismic waves near the solar equator in the presence of magnetic fields deep within the solar radiative zone. We find that reasonable magnetic fields can significantly alter the shapes of the wave profiles for helioseismic g-modes. They can do so because the existence of density gradients allows g-modes to resonantly excite Alfven waves, causing mode energy to be funnelled along magnetic field lines, away from the solar equatorial plane. The resulting wave forms show comparatively sharp spikes in the density profile at radii where these resonances take place. We estimate how big these waves might be in the Sun, and perform a first search for observable consequences. We find …
Southern-Tyrrhenian seismicity in space-time-magnitude domain
2006
An analysis is conducted on a catalogue containing more than 2000 seismic events occurred in the southern Tyrrhenian Sea between 1988 and October 2002, as an attempt to characterise the main seismogenetic processes active in the area in space, time and magnitude domain by means of the parameters of phenomenological laws. We chose to adopt simple phenomenological models, since the low number of data did not allow to use more complex laws. The two main seismogenetic volumes present in the area were considered for the purpose of this work. The first includes a nearly homogeneous distribution of hypocentres in a NW steeply dipping layer as far as a…
Spatial Analysis, Cartography and Climate
2010
International audience
New insights into the neolithisation process in southwest Europe according to spatial density analysis from calibrated radiocarbon dates
2017
The agricultural way of life spreads throughout Europe via two main routes: the Danube corridor and the Mediterranean basin. Current archaeological literature describes the arrival to the Western Mediterranean as a rapid process which involves both demic and cultural models, and in this regard, the dispersal movement has been investigated using mathematical models, where the key factors are time and space. In this work, we have created a compilation of all available radiocarbon dates for the whole of Iberia, in order to draw a chronological series of maps to illustrate temporal and spatial patterns in the neolithisation process. The maps were prepared by calculating the calibrated 14C date …
Characterizing a hybrid zone between a cryptic species pair of freshwater snails.
2015
Characterizing hybrid zones and their dynamics is a central goal in evolutionary biology, but this is particularly challenging for morphologically cryptic species. The lack of conspicuous divergence between parental types means intermediate hybrid forms often go undetected. We aimed to detect and characterize a suspected hybrid zone between a pair of morphologically cryptic lineages of the freshwater snail, Radix. We sampled Radix from across a contact zone between two mitochondrial lineages (Radix balthica and an undescribed lineage termed 'MOTU3') and detected admixture between two nuclear genotype clusters, which were significantly but not categorically associated with the mitochondrial …
Evenness, biodiversity, and ecosystem function of intertidal communities along the Italian coasts: Experimental short-term response to ambient and ex…
2023
Biodiversity can promote ecosystem functioning in both terrestrial and marine environments, emphasizing the neces- sity ofbiodiversity conservation in order to preserve critical ecosystem functions and associated services. However, the role of biodiversity in buffering ecosystem functioning under extreme events caused by climate change remains a major scientific issue, especially for intertidal systems experiencing stressors from both terrestrial and marine drivers. We performed a regional-scale field experiment along the Italian coast to investigate the response of unmanipulated intertidal communities (by using a natural biodiversity gradient) to low tide aerial exposure to both ambient an…
Model, software and database for line-mixing effects in the nu3 and nu4 bands of CH4 and tests using laboratory and planetary measurements - II : H2 …
2006
International audience; The absorption shapes of the nu(2), nu(3) and nu(4) infrared bands of CH4 perturbed by H-2 in large ranges of pressure and temperature have been measured in the laboratory. In order to model these spectra, the theoretical approach accounting for line-mixing effects proposed for CH4-N-2 and CH4-air and successfully tested in the companion paper (1), is used. As before, state-to-state rotational rates are used together with some empirical parameters that are deduced from a fit of a single room temperature spectrum of the nu(3) band at about 50 atm. The comparisons between measured and calculated spectra in the nu(3) and nu(4) regions under a vast variety of conditions …
INTEGRAL and RXTE observations of accreting millisecond pulsar IGR J00291+5934 in outburst
2005
Simultaneous observations of the accretion-powered millisecond pulsar IGR J00291+5934 by International Gamma-Ray Astrophysics Laboratory and Rossi X-ray Timing Explorer during the 2004 December outburst are analysed. The average spectrum is well described by thermal Comptonization with an electron temperature of 50 keV and Thomson optical depth tau_T ~ 1 in a slab geometry. The spectral shape is almost constant during the outburst. We detect a spin-up of the pulsar with nudot=8.4x10E-13 Hz/s. The ISGRI data reveal the pulsation of X-rays at a period of 1.67 milliseconds up to ~150 keV. The pulsed fraction is shown to increase from 6 per cent at 6 keV to 12--20 per cent at 100 keV. This is n…
Vicarious calibration of MERIS over dark waters in the near infrared
2005
Abstract We propose to evaluate the calibration of MERIS (MEdium Resolution Imaging Spectrometer) over dark waters in the near infrared. We work with 5 months of data, from July to November 2003, over five world sites: Venice and Lampedusa in Italy, El Arenosillo in Spain, MOBY/Lanai and CalCOFI/San Nicolas in the United States. The sites are all equipped with a CIMEL station that forms part of the AERONET network. The basic idea is to associate CIMEL sky radiance measurements with MERIS level-1b data in a twin geometry which corresponds to the same scattering angle. This vicarious calibration relies on an accurate description of the atmospheric scattering based on the CIMEL measurements. A…
SPEECH AND SILENCE IN CICERO'S FINAL DAYS
2014
Composed in spring of 46 BC, Cicero's Brutus emphasizes oratorical silence, in stark contrast with the prominence of the speech act found in the Pro Marcello and first Philippic. Yet in the face of those difficult times and amidst the silence that such times engender, Cicero ironically finds his voice. This paper will demonstrate Cicero's acute awareness, in his final days, of the need to employ his rediscovered voice in light of eloquence's changed role in Rome's new political climate.