University of Grenoble

About: University of Grenoble is a education organization based out in Saint-Martin-d'Hères, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 25658 authors who have published 45143 publications receiving 909760 citations.

Shadows and spirals in the protoplanetary disk HD 100453

Abstract: ESO; CNRS (France); MPIA (Germany); INAF (Italy); FINES (Switzerland); NOVA (Netherlands); European Commission, Optical Infrared Coordination Network for Astronomy (OPTICON) [RII3-Ct-2004-001566, 226604, 312430]; Programme National de Planetologie (PNP); Programme National de Physique Stellaire (PNPS) of CNRS-INSU; French Labex OSUG@2020 (Investissements d'avenir) [ANR10 LABX56]; NASA's Science Mission Directorate; DISCSIM project - European Research Council [341137]; Italian Ministry of Education, University, and Research

Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network

Abstract: Long-term monitoring of data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS) project was funded by the European Commission (http://www.gmos.eu) and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010-2015), analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both.

Indefinite Causal Order in a Quantum Switch

Abstract: Quantum mechanics allows events to happen with no definite causal order: this can be verified by measuring a causal witness, in the same way that an entanglement witness verifies entanglement. Here, we realize a photonic quantum switch, where two operations (A) over cap and (B) over cap act in a quantum superposition of their two possible orders. The operations are on the transverse spatial mode of the photons; polarization coherently controls their order. Our implementation ensures that the operations cannot be distinguished by spatial or temporal position-further it allows qudit encoding in the target. We confirm our quantum switch has no definite causal order by constructing a causal witness and measuring its value to be 18 standard deviations beyond the definite-order bound.

Modulation of Wind-Work by Oceanic Current Interaction with the Atmosphere

Abstract: In this study uncoupled and coupled ocean-atmosphere simulations are carried out for the California Upwelling System to assess the dynamic ocean-atmosphere interactions, viz.,the ocean surface current feedback to the atmosphere. We show the current feedback by modulating the energy transfer from the atmosphere to the ocean, controls the oceanic Eddy Kinetic Energy (EKE). For the first time, we demonstrate the current feedback has an effect on the surface stress and an counteracting effect on the wind itself. The current feedback acts as an oceanic eddy killer, reducing by half the surface EKE, and by 27% the depth-integrated EKE. On one hand, it reduces the coastal generation of eddies by weakening the surface stress and hence the near-shore supply of positive wind work (i.e., the work done by the wind on the ocean). On the other hand, by inducing a surface stress curl opposite to the current vorticity, it deflects energy from the geostrophic current into the atmosphere and dampens eddies. The wind response counteracts the surface stress response. It partly re-energizes the ocean in the coastal region and decreases the offshore return of energy to the atmosphere. Eddy statistics confirm the current feedback dampens the eddies and reduces their lifetime, improving the realism of the simulation. Finally, we propose an additional energy element in the Lorenz diagram of energy conversion, viz., the current-induced transfer of energy from the ocean to the atmosphere at the eddy scale.

Improved limit to the diffuse flux of ultrahigh energy neutrinos from the Pierre Auger Observatory

Abstract: Neutrinos in the cosmic ray flux with energies near 1 EeV and above are detectable with the Surface Detector array (SD) of the Pierre Auger Observatory. We report here on searches through Auger data from 1 January 2004 until 20 June 2013. No neutrino candidates were found, yielding a limit to the diffuse flux of ultrahigh energy neutrinos that challenges the Waxman-Bahcall bound predictions. Neutrino identification is attempted using the broad time structure of the signals expected in the SD stations, and is efficiently done for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for "Earth-skimming" neutrino interactions in the case of tau neutrinos. In this paper the searches for downward-going neutrinos in the zenith angle bins 60°-75°and 75°-90°as well as for upward-going neutrinos, are combined to give a single limit. The 90% C.L. single-flavor limit to the diffuse flux of ultrahigh energy neutrinos with an E-2 spectrum in the energy range 1.0×1017eV-2.5×1019eV is Eν2dNν/dEν<6.4×10-9GeVcm-2s-1sr-1.