Description: Sea ice leads play an essential role in ocean-ice-atmosphere exchange, in ocean circulation, geochemistry and in ice dynamics. Their precise detection is crucial for altimetric estimations of sea ice thickness and volume. This study evaluates the performance of the SARAL/AltiKa altimeter to detect leads and to monitor their spatio-temporal dynamics. We show that a pulse peakiness parameter (PP) used to detect leads by Envisat RA-2 and ERS-1,-2 altimeters is not suitable because of saturation of AltiKa return echoes over the leads. The signal saturation results in loss of 6–10% of PP data over sea ice. We propose a different parameter: maximal power of waveform, and define the threshold to discriminate the leads. Our algorithm can be applied from December until May. It detects well the leads of small and medium size: from 200 m to 3–4 km. So, the combination of the high-resolution altimetric estimates with low-resolution thermal infra-red or radiometric lead fraction products could enhance the capability of remote sensing to monitor sea ice fracturing.

Description: ABSTRACT The technical and economic success of a CO 2 geological storage project requires the preservation of the site injectivity and integrity properties over its lifetime. Unlike conventional hydrocarbon gas injection, CO 2 injection may imply geochemical reactions between acidified pore fluids and target reservoir formations, leading to modifications of their poromechanical properties. To date, the chemical effects on the host rock mechanical behaviour are not satisfactorily taken into account in site-scale numerical models of CO 2 injection, mainly due to a lack of quantitative data. The present experimental work aims at characterizing the evolution of carbonate poromechanical properties induced by acid alteration. Unlike standard experimental approaches, the implemented alteration method induces a homogeneous dissolution pattern, which ensures reliable poromechanical measurements on altered samples. These well-controlled alteration conditions allow a proper interpretation of the test results through the macroscopic continuous approach of poromechanics. Petrophysical, geomechanical, and petroacoustic properties of outcrop carbonate samples have been measured for different levels of alteration to mimic long-term exposure to reactive brine. The obtained experimental data show clear trends of chemically induced mechanical weakening. Nuclear magnetic resonance measurements and microscanner imaging performed before and after alteration have provided complementary insights into the alteration effects at the microscopic scale.

Description: Petiroc and Citiroc are the two latest ASIC from Weeroc dedicated to SiPM read-out. Petiroc is a 16-channel front-end ASIC designed to readout silicon photomultipliers (SiPMs) for particle time-of-flight measurement applications. It combines a very fast and low-jitter trigger with an accurate charge measurement. Citiroc is a 32-channel front-end ASIC designed to readout silicon photo-multipliers (SiPM). It allows triggering down to 1/3 pe and provides the charge measurement with a good noise rejection. Moreover, Citiroc outputs the 32-channel triggers with a high accuracy (100 ps). Each channel of both ASICs combines a trigger path with an accurate charge measurement path. An adjustment of the SiPM high voltage is possible using a channel-by-channel input DAC. That allows a fine SiPM gain and dark noise adjustment at the system level to correct for the non-uniformity of SiPMs. Timing measurement down to 16 ps RMS jitter for Petiroc and 100 ps RMS for Ci...

Description: Atopic dermatitis (AD) is a chronic allergic dermatosis characterized by epidermal thickening and dermal inflammatory infiltrates with a dominant Th2 profile during the acute phase, whereas a Th1 profile is characteristic of the chronic stage. Among chemokines and chemokine receptors associated with inflammation, increased levels of CX 3 CL1 (fractalkine) and its unique receptor, CX 3 CR1, have been observed in human AD. We have thus investigated their role and mechanism of action in experimental models of AD and psoriasis. AD pathology and immune responses, but not psoriasis, were profoundly decreased in CX 3 CR1-deficient mice and upon blocking CX 3 CL1–CX 3 CR1 interactions in wild-type mice. CX 3 CR1 deficiency affected neither antigen presentation nor T cell proliferation in vivo upon skin sensitization, but CX 3 CR1 expression by both Th2 and Th1 cells was required to induce AD. Surprisingly, unlike in allergic asthma, where CX 3 CL1 and CX 3 CR1 regulate the pathology by controlling effector CD4 + T cell survival within inflamed tissues, adoptive transfer experiments established CX 3 CR1 as a key regulator of CD4 + T cell retention in inflamed skin, indicating a new function for this chemokine receptor. Therefore, although CX 3 CR1 and CX 3 CL1 act through distinct mechanisms in different pathologies, our results further indicate their interest as promising therapeutic targets in allergic diseases.

Description: Article Topological order for sound remains largely unexplored. Here, Khanikaev et al . introduce the concept of topological order in classical acoustics, realizing robust topological protection and one-way edge propagation of sound in a suitably designed resonator lattice, thus expanding the ability to tailor acoustic waves. Nature Communications doi: 10.1038/ncomms9260 Authors: Alexander B. Khanikaev, Romain Fleury, S. Hossein Mousavi, Andrea Alù

Description: In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion.

Description: The SIN’XS project is a three-year activity (May 2022 – May 2025) funded by ESA in the frame of the Polar Science Cluster. In light of rapid changes of the Arctic and Antarctic sea ice cover, continued and improved observations, understanding, and predictions of its thickness are particularly important for a range of fields from climate studies to offshore operations in ice. Systematic and accurate ice thickness observations are now available from several satellite missions. However, they differ in used processing algorithms and assumptions, temporal and spatial coverage and resolution, and applicability to stakeholder needs like modelling and assimilation, numerical weather prediction, and ship routing. These differences between products have so far complicated the consistent use of the various data products and there is little consensus about Arctic and Antarctic Sea ice volume variability and change. The Sea Ice-thickness product iNter-comparison eXerciSe (SIN’XS) will identify some of these gaps by carrying out in-depth intercomparisons of a wide range of satellite ice thickness products from altimetry and other methods, in close collaboration with an international community of scientific and operational sea ice experts, and in partnership with the WMO Global Cryosphere Watch (GCW). It will develop joint protocols for the intercomparison of ice thickness products and their validation, based on established approaches from the QA4EO project and by further developing a framework for Fiducial Reference Measurements (FRMs). SIN’XS will develop an online system to engage the community with data submission and to support scientific analysis of the data sets and intercomparisons.