Symmetry-breaking phase transition in a dynamical decision model

We consider a simple decision model in which a set of agents randomly choose one of two competing shops selling the same perishable products (typically food). The satisfaction of agents with respect to a given store is related to the freshness of the previously bought products. Agents select with a higher probability the store they are most satisfied with. Studying the model from a statistical physics perspective, both through numerical simulations and mean-field analytical methods, we find a rich behaviour with continuous and discontinuous phase transitions between a symmetric phase where both stores maintain the same level of activity, and a phase with broken symmetry where one of the two shops attracts more customers than the other.Comment: 13 pages, 6 figures, submitted to JSTA

Synthesis by solid route and physicochemical characterizations of blends of calcium orthophosphate powders and mesoporous silicon particles

The purpose of the study was to investigate the synthesis of economic calcium phosphate powders from recycled oyster shells, using a ball milling method. The oyster shell powder and a calcium pyrophosphate powder were used as starting materials and ball milled, then heat treated at 1,050°C for 5 h to produce calcium phosphate powders through a solid-state reaction. Electrochemically synthesized mesoporous silicon microparticles were then added to the prepared phosphate powders by mechanical mixer. The final powders were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy to analyze their chemical composition and determine the most suitable process conditions. The biocompatibility of the produced powders was also tested in vitro using murine cells and the results showed good biocompatibility

Measuring currents, ice drift, and waves from space: the Sea Surface KInematics Multiscale monitoring (SKIM) concept

We propose a new satellite mission that uses a near-nadir Ka-band Doppler radar to measure surface currents, ice drift and ocean waves at spatial scales of 40?km and more, with snapshots at least every day for latitudes 75 to 82, and every few days otherwise. The use of incidence angles at 6 and 12 degrees allows a measurement of the directional wave spectrum which yields accurate corrections of the wave-induced bias in the current measurements. The instrument principle, algorithm for current velocity and mission performance are presented here. The proposed instrument can reveal features on tropical ocean and marginal ice zone dynamics that are inaccessible to other measurement systems, as well as a global monitoring of the ocean mesoscale that surpasses the capability of today?s nadir altimeters. Measuring ocean wave properties facilitates many applications, from wave-current interactions and air-sea fluxes to the transport and convergence of marine plastic debris and assessment of marine and coastal hazards

Altimetry for the future: Building on 25 years of progress

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

Altimetry for the future: building on 25 years of progress

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

Symmetry-breaking phase transition in a dynamical decision model

13 pages, 6 figures, submitted to JSTATInternational audienceWe consider a simple decision model in which a set of agents randomly choose one of two competing shops selling the same perishable products (typically food). The satisfaction of agents with respect to a given store is related to the freshness of the previously bought products. Agents select with a higher probability the store they are most satisfied with. Studying the model from a statistical physics perspective, both through numerical simulations and mean-field analytical methods, we find a rich behaviour with continuous and discontinuous phase transitions between a symmetric phase where both stores maintain the same level of activity, and a phase with broken symmetry where one of the two shops attracts more customers than the other

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Mice exposed to food-grade titanium dioxide from in utero life to adulthood show sex-specific gut microbiota and metabolic disorders which are aggravated under Western-diet

International audienceBackground: Food additives are one major hallmark of ultra-processed food in the Western diet, a food habit often associated with metabolic disorders. Among these additives, the whitener and opacifying agent titanium dioxide (TiO2, E171 in EU) raises public health issues due to systemic passage, organ accumulation (including placenta) and a maternofetal passage of TiO2 nanoparticles (found in the meconium) in human, showing early life exposure. In this context, exposure to TiO2 with biocidal properties could alter the gut colonization by the microbiota that plays a key role in intestinal and metabolic functions, leading to health effects at adulthood. Our aim in mice was to assess the fetal passage of TiO2 (E171) particles given to dams and the consequences on gut microbiota and metabolic functions of the offspring.Methods: Female mice (F0) were exposed to a control or E171-enriched normal diet at a human dose level (10 mg/kg bw/day) during pregnancy and lactation. At weaning, part of the descendants (F1) were fed with the same diet as their mother and the other part received a Western diet (WD) supplemented or not with the E171 (10 mg/kg bw/day) until postnatal day (PND) 150. Total fetal titanium (Ti) content was measured by ICP-MS at day 18 of pregnancy, and in the liver of F1 descendants at PND150. Intestinal inflammation and microbiota composition were studied at PND150 using ELISA for cytokines and 16S gene sequencing, respectively. Metabolic status was evaluated using oral glucose tolerance test and fasting insulin.Results: Compared to controls, high Ti level was detected in fetuses of E171-exposed mothers, while further liver Ti accumulation was evidenced at PND150 in F1 descendants fed with the same E171-enriched diet, regardless of the sex. Under normal diet, chronic E171 exposure starting in utero increased production of the pro-inflammatory cytokine IL1β in the colon of adult F1 males. Changes in the gut microbiota composition occurred in males only, showing an increase of β-diversity and Firmicutes/Bacteroidetes ratio. This occurred concomitantly to glucose intolerance and higher fasting insulin levels, while the same E171 treatment fostered WD-induced colon inflammation and glucose intolerance. In contrast, decreased secretion of pro- (IL1β, TNFα, IFNγ, IL17) and anti-(IL10) inflammatory cytokines occurred in the colon of E171-exposed F1 females under normal diet, while the metabolic alterations induced by WD showed no worsening.Conclusions: These results showed that a long-term exposure to food-grade TiO2 (E171) starting from in utero life alters intestinal and metabolic homeostasis in a sex-dependent manner, characterized by altered glucose metabolism, gut dysbiosis and worsening of WD-induced metabolic disorders in male mice only. Taken together, these data suggest that a lifespan exposure to TiO2 from dietary sources could both initiate and promote the development of metabolic disorders in humans

Mice exposed to food-grade TiO 2 from in utero life to adulthood show sex-specific gut microbiota and metabolic disorders

International audienceThe use of titanium dioxide (TiO 2) particles as a food additive (E171 in EU) in ultra-processed foods raises public health issues. Our previous study showed transplacental passage of TiO 2 nanoparticles in the human placenta, and presence of TiO 2 particles in meconium, demonstrating foetal exposure. Due to biocidal properties of TiO 2 , whether E171 exposure starting early during pregnancy may alter the establishment of gut microbiota homeostasis with potential deleterious effects at adulthood has not been explored. The current study in mice aimed to assess the perinatal fate of E171 given to dams and the consequences on gut microbiota and metabolic functions of the offspring. Female mice were exposed to a control or E171-enriched diet at a human relevant level (10 mg/kg bw/day) during pregnancy and lactation until weaning of pups, then the descendants were fed with the same diet as their mother until postnatal day (PND) 150. Oral glucose tolerance and fasting insulin were assessed at PND143. At PND150, all mice were sacrificed and gut microbiota composition as well as intestinal pro-and anti-inflammatory cytokine production were measured by 16S gene sequencing and ELISA, respectively. Biodistribution of TiO 2 particles was also studied by ICP-MS in fetus at day 18 of pregnancy, and in the liver at PND150. In E171-exposed mice, higher Ti level was first detected in fetus, and Ti accumulation was reported in liver at PND150 compared to controls regardless of the sex. Changes in gut microbiota composition occurred in E171-exposed male only, showing increased βdiversity and of the Firmicutes/Bacteroidetes ratio. Increased production of the pro-inflammatory cytokine IL1β in the colon as well as glucose intolerance and higher fasting insulin levels were also reported in E171-exposed male relative to controls. In contrast, decreased secretion of pro-(IL1β, TNFα, IFNγ, IL17) and anti-(IL10) inflammatory cytokines occurred in the colon of E171-exposed females, without other changes. These results showed that long term exposure to E171 from in utero life alters intestinal and metabolic homeostasis in a sex-dependent manner, characterized by altered glucose metabolism and gut dysbiosis in male mice only