Search results for "flux"

Une envahissante dans le paysage : cas de l’ambroisie à feuilles d’armoise

2014

L’ambroisie à feuilles d’armoise (Ambrosia artemisiifolia L.) est une espèce annuelle envahissante introduite en France à la fin du XIXe siècle. Plante rudérale, tolérante à de nombreux stress, l’ambroisie se développe essentiellement dans les habitats perturbés. Les principaux milieux occupés sont les parcelles agricoles, les bords de route et les zones perturbées par les activités anthropiques (jachères industrielles, zone de dépôt de matériaux …). Les berges de rivière constituent le seul habitat naturel dans lequel l’ambroisie peut former d’importantes populations. La semence d’ambroisie n’a pas de structure particulière favorisant son invasion. Trop lourde pour être dispersée par le ve…

Les frontières de la libre circulation dans le football européen : vers une mondialisation des flux de joueurs?

2005

Les frontières étatiques sont de moins en moins pertinentes pour définir les limites entre territoires souverains. En termes de mobilité des personnes, cependant, bien que parfois déplacées à la périphérie de nouveaux territoires en gestation, elles continuent à jouer un rôle primordial dans le contrôle et la régulation des flux, surtout pour les migrants non qualifiés. Notre article se concentre sur le cas des footballeurs professionnels, une population le plus souvent considérée comme faisant partie d’une élite migratoire bien intégrée dans un marché du travail mondial, pour laquelle les frontières n’ont plus d’importance. En réalité, nous mettons en exergue l’existence de logiques géogra…

The gallium anomaly revisited

2019

The gallium anomaly, i.e. the missing electron-neutrino flux from $^{37}$Ar and $^{51}$Cr electron-capture decays as measured by the GALLEX and SAGE solar-neutrino detectors, has been among us already for about two decades. We present here a new estimate of the significance of this anomaly based on cross-section calculations using nuclear shell-model wave functions obtained by exploiting recently developed two-nucleon interactions. The gallium anomaly of the GALLEX and SAGE experiments is found to be smaller than that obtained in previous evaluations, decreasing the significance from 3.0σ to 2.3σ. This result is compatible with the recent indication in favor of short-baseline ν¯e disappeara…

Oesophageal pH/impedance monitoring in children treated for oesophageal atresia

2008

Characteristics of induced sputum in adult with mild asthma and in patients with asthma-like symptoms by gastroesophageal reflux disease.

2007

Volcanic Gas Emissions Along the Colombian Arc Segment of the Northern Volcanic Zone (CAS-NVZ): Implications for volcano monitoring and volatile budg…

2019

Studying spatial and temporal trends in volcanic gas compositions and fluxes is crucial both to volcano monitoring and to constrain the origin and recycling efficiency of volatiles at active convergent margins. New volcanic gas compositions and volatile fluxes are here reported for Nevado del Ruiz, Galeras, and Purace, three of the most persistently degassing volcanoes located in the Colombian Arc Segment of the Northern Volcanic Zone. At Nevado del Ruiz, from 2014 to 2017, plume emissions showed an average molar CO2/S-T ratio of 3.9 +/- 1.6 (S-T is total sulfur, S). Contemporary, fumarolic chemistry at Galeras progressively shifted toward low-temperature, S-depleted fumarolic gas discharge…

Substrate quality of drained organic soils—Implications for carbon dioxide fluxes

2021

Ultraviolet camera measurements of passive and explosive (Strombolian) sulphur dioxide emissions at Yasur volcano, Vanuatu

2020

Here, we present the first ultraviolet (UV) camera measurements of sulphur dioxide (SO2) flux from Yasur volcano, Vanuatu, for the period 6–9 July 2018. These data yield the first direct gas-measurement-derived calculations of explosion gas masses at Yasur. Yasur typically exhibits persistent passive gas release interspersed with frequent Strombolian explosions. We used compact forms of the “PiCam” Raspberry Pi UV camera system [1,2] powered through solar panels to collect images. Our daily median SO2 fluxes ranged from 4 to 5.1 kg s−1, with a measurement uncertainty of −12.2% to +14.7%, including errors from the gas cell calibration drift, uncertainties in plume direction and distance, and…

Mapping fumarolic fields in volcanic areas: A methodological approach based on the case study of La Fossa cone, Vulcano island (Italy)

2016

Abstract Changes in the activity state of a volcano can be inferred by monitoring the steam flux from fumarolic fields, in terms of 4D (x, y, z, time) variations in temperature and extension of the zone. During the last decades, several studies in this field have been conducted worldwide, and at Vulcano island (Italy) in particular. Both direct and remotely sensed measurements have been used for identifying thermally anomalous areas, but the possible role of the hydrothermal alteration of volcanic products, producing a sealing effect that obscures the surface thermal evidence of fumarolic activity, have never been explored. The novelty of the present study, carried out at La Fossa cone (Vul…

First observations of the fumarolic gas output from a restless caldera: Implications for the current period of unrest (2005-2013) at Campi Flegrei

2013

[1] The fumarolic gas output has not been quantified for any of the currently deforming calderas worldwide, due to the lack of suitable gas flux sensing techniques. In view of resumption of ground uplift (since 2005) and the associated variations in gas chemistry, Campi Flegrei, in southern Italy, is one of the restless calderas where gas flux observations are especially necessary. Here we report the first ever obtained estimate of the Campi Flegrei fumarolic gas output, based on a set of MultiGAS surveys (performed in 2012 and 2013) with an ad-hoc-designed measurement setup. We estimate that the current Campi Flegrei fumarolic sulphur (S) flux is low, on the order of 1.5–2.2 tons/day, sugg…