L'étude des phénomènes de marée gravimétrique

Cet article présente une description des phénomènes de marée terrestre et des méthodes de mesure. Les résultats des profils mondiaux de marée gravimétrique sont corrigés des effets indirects liés aux marées océaniques. Une corrélation entre marées gravimétriques, flux de chaleur et tectonique globale est proposé

Tidal gravity observations at Mt. Etna and Stromboli: results concerning the modeled and observed tidal factors

Continuous gravity observations performed in the last few years, both at Mt. Etna and Stromboli, have prompted the need to improve the tidal analysis in order to acquire the best corrected data for the detection of volcano related signals. On Mt. Etna, the sites are very close to each other and the expected tidal factor differences are negligible. It is thus useful to unify the tidal analysis results of the different data sets in a unique tidal model. This tidal model, which can be independently confirmed by a modeling of the tidal parameters based on the elastic response of the Earth to tidal forces and the computation of the ocean tides effects on gravity, is very useful for the precise tidal gravity prediction required by absolute or relative discrete gravity measurements. The change in time of the gravimeters’ sensitivity is also an important issue to be checked since it affects not only the results of tidal analysis but also the accuracy of the observed gravity changes. Conversely, if a good tidal model is available, the sensitivity variations can be accurately reconstructed so as to retune observed tidal records with the synthetic tide, since the tidal parameters are assumed to be constant at a given location

High precision tilt observation at Mt. Etna Volcano, Italy

In 2007-2008, we installed on Mt. Etna two deep tilt stations using high resolution, self-leveling instruments. These installations are the result of accurate instrument tests, site selection, drilling and sensor positioning that has allowed detecting variations related to the principal diurnal and semidiurnal tides for first time on Mt. Etna using tilt data. We analyzed the tidal effects recorded on tilt signals and we removed tidal effects from signals, thereby allowing to detect changes of about 20 nanoradians with a considerable improvement respect to the previous installation. Tilt changes have accompanied the Mt. Etna main eruptive phases and are generally related to the rapid rise of magma and formation of dikes and eruptive fissures. However, tilt changes characterize lava fountains, earthquakes and inflation-deflation phases. The 2008-2009 eruption represents an example of the potential of these tiltmeters providing new perspectives for highly precise monitoring of ground deformation on volcanoes

Clinical Practice Guidelines for Childbearing Female Candidates for Bariatric Surgery, Pregnancy, and Post-partum Management After Bariatric Surgery

Emerging evidence suggests that bariatric surgery improves pregnancy outcomes of women with obesity by reducing the rates of gestational diabetes, pregnancy-induced hypertension, and macrosomia. However, it is associated with an increased risk of a small-for-gestational-age fetus and prematurity. Based on the work of a multidisciplinary task force, we propose clinical practice recommendations for pregnancy management following bariatric surgery. They are derived from a comprehensive review of the literature, existing guidelines, and expert opinion covering the preferred type of surgery for women of childbearing age, timing between surgery and pregnancy, contraception, systematic nutritional support and management of nutritional deficiencies, screening and management of gestational diabetes, weight gain during pregnancy, gastric banding management, surgical emergencies, obstetrical management, and specific care in the postpartum period and for newborns

The “resort effect”: Can tourist islands act as refuges for coral reef species?

There is global consensus that marine protected areas offer a plethora of benefits to the biodiversity within and around them. Nevertheless, many organisms threatened by human impacts also find shelter in unexpected or informally protected places. For coral reef organisms, refuges can be tourist resorts implementing local environment-friendly bottom-up management strategies. We used the coral reef ecosystem as a model to test whether such practices have positive effects on the biodiversity associated with de facto protected areas.USAI

The Enigma of Soil Animal Species Diversity Revisited: The Role of Small-Scale Heterogeneity

Peer reviewedPublisher PD

An European Tidal Gravity Profile over a 30º Latitude difference (Kevo - Bruxelles - Madrid)

Comunicación presentada en el "X Symposium Internacional de Mareas Terrestres", celebrado en Madrid, en 1985, y publicada en "Proceedings [of the] X International Symposium on Earth Tides".Tidal gravlty measuraments have been performed ln 1984-85 at Kevo (North Flnland). Bruxelles and Madrld wlth two LaCoste-Rombarg model"G grav1metars transformed lnto zara method lnstruments. All grav1meters wara normallzad at Brussels. Accordlng to the Wahr modelo a thirty degrees latltude difference should produce more than one per cent dacrease of the ó factor between Madr1d and Kevo. Oue to the uncerta1nties ln tha oceanic"loadlng computat10ns we cannot der1va f1nnconclus10ns for the semldlurnal wava5. The lat1tude effeet 15 elear1y seen on the dlurnal waves betwaen Bruxellas and Kevo but not between Madrld and Bruxe11es. It may be concludad that local anomalles may eonceal the latltude effect.Peer reviewe

Seasonal height change influence in GPS and gravimetric campaign data

Low motion rates, typical of intraplate settings, make it particularly difficult to isolate a tectonic signal in vertical displacements of the ground dominated by near-surface influences. Since the spring 2003, we have performed half-yearly GPS and gravimetric campaigns in NE Ardenne in order to evaluate the seasonal changes imposed to the ground height by groundwater variations. The GPS height data show an excellent negative correlation with a proxy for groundwater variations, based on rainfall in the 6 months before the survey, that allows a reliable correction of the measured height changes. During the 2003-2005 time span, the seasonal groundwater-dependent height changes have amounted to a maximum 7.5 mm. The gravimetric campaigns were able to detect reliably only gravity changes larger than 10 mu gal, which corresponds to the upper limit of the gravity changes associated with the proposed groundwater-GPS model. No conclusive result may therefore be derived from the gravity observations. (c) 2006 Elsevier Ltd. All rights reserved