Showing papers by "University of Avignon published in 2018"

Exploring gravity with the MIGA large scale atom interferometer

Abstract: We present the MIGA experiment, an underground long baseline atom interferometer to study gravity at large scale. The hybrid atom-laser antenna will use several atom interferometers simultaneously interrogated by the resonant mode of an optical cavity. The instrument will be a demonstrator for gravitational wave detection in a frequency band (100 mHz-1 Hz) not explored by classical ground and space-based observatories, and interesting for potential astrophysical sources. In the initial instrument configuration, standard atom interferometry techniques will be adopted, which will bring to a peak strain sensitivity of ⋅ 2 10 Hz / 13 − at 2 Hz. This demonstrator will enable to study the techniques to push further the sensitivity for the future development of gravitational wave detectors based on large scale atom interferometers. The experiment will be realized at the underground facility of the Laboratoire Souterrain Bas Bruit (LSBB) in Rustrel-France, an exceptional site located away from major anthropogenic disturbances and showing very low background noise. In the following, we present the measurement principle of an in-cavity atom interferometer, derive the method for Gravitational Wave signal extraction from the antenna and determine the expected strain sensitivity. We then detail the functioning of the different systems of the antenna and describe the properties of the installation site.

The Chemical Reactivity of Anthocyanins and Its Consequences in Food Science and Nutrition

Abstract: Owing to their specific pyrylium nucleus (C-ring), anthocyanins express a much richer chemical reactivity than the other flavonoid classes. For instance, anthocyanins are weak diacids, hard and soft electrophiles, nucleophiles, prone to developing π-stacking interactions, and bind hard metal ions. They also display the usual chemical properties of polyphenols, such as electron donation and affinity for proteins. In this review, these properties are revisited through a variety of examples and discussed in relation to their consequences in food and in nutrition with an emphasis on the transformations occurring upon storage or thermal treatment and on the catabolism of anthocyanins in humans, which is of critical importance for interpreting their effects on health.

OZCAR: The French Network of Critical Zone Observatories

Abstract: The French critical zone initiative, called OZCAR (Observatoires de la Zone Critique–Application et Recherche or Critical Zone Observatories–Application and Research) is a National Research Infrastructure (RI). OZCAR-RI is a network of instrumented sites, bringing together 21 pre-existing research observatories monitoring different compartments of the zone situated between “the rock and the sky,” the Earth’s skin or critical zone (CZ), over the long term. These observatories are regionally based and have specific initial scientific questions, monitoring strategies, databases, and modeling activities. The diversity of OZCAR-RI observatories and sites is well representative of the heterogeneity of the CZ and of the scientific communities studying it. Despite this diversity, all OZCAR-RI sites share a main overarching mandate, which is to monitor, understand, and predict (“earthcast”) the fluxes of water and matter of the Earth’s near surface and how they will change in response to the “new climatic regime.” The vision for OZCAR strategic development aims at designing an open infrastructure, building a national CZ community able to share a systemic representation of the CZ , and educating a new generation of scientists more apt to tackle the wicked problem of the Anthropocene. OZCAR articulates around: (i) a set of common scientific questions and cross-cutting scientific activities using the wealth of OZCAR-RI observatories, (ii) an ambitious instrumental development program, and (iii) a better interaction between data and models to integrate the different time and spatial scales. Internationally, OZCAR-RI aims at strengthening the CZ community by providing a model of organization for pre-existing observatories and by offering CZ instrumented sites. OZCAR is one of two French mirrors of the European Strategy Forum on Research Infrastructure (eLTER-ESFRI) project.

Assessing and mapping urban resilience to floods with respect to cascading effects through critical infrastructure networks

Abstract: The urban environment is very concerned by network failures. These failures are propagating risks in area generally considered as non-vulnerable. There are various causes of possible disruptions in critical infrastructure networks (CIs), such as natural hazards, technological hazards, accidents, human errors and terrorism. However, in the last years it became harder to identify the possible failures of complex networks and to forecast their effects on the urban environment. New challenges such as climate change and the ageing of CIs are likely to increase the difficulty to secure the lifelines, raising the potential of damages and economic losses caused by failures. This paper suggests some new methods to assess and map resilience levels to floods taking into account critical infrastructure networks as risk propagators at different spatial scales. The conclusions support the development of innovative strategies and decision support systems for new resilient urban environments.

Thermodynamics, transport phenomena, and electrochemistry of external field-assisted nonthermal food technologies.

Abstract: Interest in the development and adoption of nonthermal technologies is burgeoning within the food and bioprocess industry, the associated research community, and among the consumers. This is evident from not only the success of some innovative nonthermal technologies at industrial scale, but also from the increasing number of publications dealing with these topics, a growing demand for foods processed by nonthermal technologies and use of natural ingredients. A notable feature of the nonthermal technologies such as cold plasma, electrohydrodynamic processing, pulsed electric fields, and ultrasound is the involvement of external fields, either electric or sound. Therefore, it merits to study the fundamentals of these technologies and the associated phenomenon with a unified approach. In this review, we revisit the fundamental physical and chemical phenomena governing the selected technologies, highlight similarities, and contrasts, describe few successful applications, and finally, identify the gaps in research.

Sporulation environment influences spore properties in Bacillus: evidence and insights on underlying molecular and physiological mechanisms.

Abstract: Bacterial spores are resistant to physical and chemical insults, which makes them a major concern for public health and industry. Spores help bacteria to survive extreme environmental conditions that vegetative cells cannot tolerate. Spore resistance and dormancy are important properties for applications in medicine, veterinary health, food safety, crop protection and other domains. The resistance of bacterial spores results from a protective multilayered structure and from the unique composition of the spore core. The mechanisms of sporulation and germination, the first stage after breaking of dormancy, and organization of spore structure have been extensively studied in Bacillus species. This review aims to illustrate how far the structure, composition and properties of spores are shaped by the environmental conditions in which spores form. We look at the physiological and molecular mechanisms underpinning how sporulation media and environment deeply affect spore yield, spore properties like resistance to wet heat and physical and chemical agents, germination and further growth. For example, spore core water content decreases as sporulation temperature increases, and resistance to wet heat increases. Controlling the fate of Bacillus spores is pivotal to controlling bacterial risks and process efficiencies in, for example, the food industry, and better control hinges on better understanding how sporulation conditions influence spore properties.

Priority actions to improve provenance decision-making

Abstract: Selecting the geographic origin-the provenance-of seed is a key decision in restoration. The last decade has seen a vigorous debate on whether to use local or nonlocal seed. The use of local seed has been the preferred approach because it is expected to maintain local adaptation and avoid deleterious population effects (e.g., maladaptation and outbreeding depression). However, the impacts of habitat fragmentation and climate change on plant populations have driven the debate on whether the local-is-best standard needs changing. This debate has largely been theoretical in nature, which hampers provenance decision-making. Here, we detail cross-sector priority actions to improve provenance decision-making, including embedding provenance trials into restoration projects; developing dynamic, evidence-based provenance policies; and establishing stronger research–practitioner collaborations to facilitate the adoption of research outcomes. We discuss how to tackle these priority actions in order to help satisfy the restoration sector’s requirement for appropriately provenanced seed.

Extraction of bioactives from fruit and vegetables: State of the art and perspectives

Abstract: Fruit and vegetables are rich in bioactive compounds that contribute to the prevention of a number of degenerative diseases. These components are also present, often in even higher concentrations, in the co-products from fruit and vegetable processing. Such fact, makes these co-products an attractive source for the extraction of bioactives, turning the extraction itself into an attractive valorization strategy for these co-products. There has been recently renewed interest in extraction methods, notably with a process intensification using physical phenomena and the search for alternative solvents. This paper will present the main bioactives in fruit and vegetables, and their co-products, and the precautions to preserve these molecules in the food processing chain, with a main focus on the pros and cons of recently proposed extraction developments, particularly on extraction mechanisms, sample pre-treatment, and solvent choice.

SNO KARST: a French network of observatories for the multidisciplinary study of critical zone processes in karst watersheds and aquifers

Abstract: Karstaquifers and watersheds represent a major source of drinking water around the world. They are also known as complex and often highly vulnerable hydrosystems due to strong surface-groundwater interactions. Improving the understanding of karst functioning is thus a major issue for the efficient management of karst groundwater resources. A comprehensive understanding of the various processes can be achieved only by studying karst systems across a wide range of spatiotemporal scales under different geological, geomorphological, climatic, and soil cover settings. The objective of the French Karst National Observatory Service (SNO KARST) is to supply the international scientific community with appropriate data and tools, with the ambition of (i) facilitating the collection of long-term observations of hydrogeochemical variables in karst, and (ii) promoting knowledge sharing and developing cross-disciplinary research on karst. This paper provides an overview of the monitoring sites and collective achievements, such as the KarstMod modular modeling platform and the PaPRIKa toolbox, of SNO KARST. It also presents the research questions addressed within the framework of this network, along with major research results regarding (i) the hydrological response of karst to climate and anthropogenic changes, (ii) the influence of karst on geochemical balance of watersheds in the critical zone, and (iii) the relationships between the structure and hydrological functioning of karst aquifers and watersheds.

Beyond the species pool: modification of species dispersal, establishment, and assembly by habitat restoration

Abstract: Species dispersal, establishment, and assembly are crucial stages of the life history of plants, and clear understanding of the governing forces and rules that shape species composition in a particular community is vital for successful ecological restoration. In this article, we focus on five aspects of seed dispersal and plant establishment, which should be considered during habitat restoration actions. In the first two sections, we discuss the success of spontaneous dispersal and establishment on restoration based on either spatial dispersal or local seed banks. In the third section, we assess the possibilities of species introduction and assisted dispersal. In the fourth section, we introduce some possibilities for the improvement of establishment success of spontaneously dispersed or introduced species. Finally, we highlight issues influencing long‐term persistence and sustainability of restored habitats, related to the alteration of management type and intensity, climate change, and spread of non‐native species. With the present article, we introduce the special issue entitled “Seed dispersal and soil seed banks – promising sources for ecological restoration” containing 15 papers by 62 authors from 10 countries arranged in the abovementioned five topics.

Biorefining of Bilberry (Vaccinium myrtillus L.) Pomace Using Microwave Hydrodiffusion and Gravity, Ultrasound-Assisted, and Bead-Milling Extraction

Abstract: Bio-refining of bilberry pomace using innovative technologies such as microwave hydro diffusion and gravity extraction (MHG) and ultrasound assisted extraction (UAE) with different concentrations of ethanol/water as the solvent was established. Bead milling was also utilized in this sequential extraction scheme to remove the lipophilic fraction. Solubility index of target polyphenols was predicted using a computational tool (COSMO-RS) and compared to experimental results obtained by in vitro antioxidant activity assessments. MHG extracts obtained using microwave power of 2 W/g had the highest Folin-Ciocalteu reducing capacity (43.46 ± 0.48 mg GAE/g of extract), total flavonoid (4.17 ± 0.04 mg QE/g of extract), total monomeric anthocyanin content (12.19 ± 0.13 mg D3GE/g of extract) and radical scavenging capacity (22.64 ± 2.23 mg TE/g of extract). In UA ethanol/water extracts the highest flavonoid (10.41 ± 0.08 mg QE/g of extract) and anthocyanin content (12.19 ± 0.51 D3GE mg/g of extract) was present in e...

Restoring Brazilian savanna ground layer vegetation by topsoil and hay transfer

Abstract: Tropical grassy biomes have been widely neglected for conservation and, after unplanned land use conversion, ecological restoration becomes urgent. The majority of interventions have been based on the misapplication of forest restoration techniques, because there are no validated techniques to restore the species-rich ground layer. In search for innovative techniques to restore the herbaceous layer of the cerrado vegetation, we carried out an experiment based upon topsoil and hay transfer, in the state of Sao Paulo, Brazil. The restoration treatments were: (1) transfer of topsoil collected at the end of the dry season; (2) topsoil collected at the end of the rainy season; (3) transfer of hay collected at the end of the dry season; (4) topsoil + hay collected at the end of the dry season; and (5) control. We used an old-growth grassland as source of material and as reference ecosystem to assess the efficacy of the restoration techniques applied to an area severely degraded after invasion by African grasses. After 211 days, hay transfer apparently inhibited germination and did not contribute to grassland vegetation recovery. Topsoil transfer, however, was effective at reintroducing herbaceous plants, including target species. The season of topsoil collection mattered: material collected at the end of the rainy season provided better results in terms of density and richness of the restored community than that from the dry season. The remaining challenge is to find sources of topsoil not invaded by exotic grasses in large enough amounts to support restoration initiatives without jeopardizing the source ecosystems.

What is the best ethanol-water ratio for the extraction of antioxidants from rosemary? Impact of the solvent on yield, composition, and activity of the extracts.

Abstract: Extracts rich in antioxidants, such as rosemary extracts, are currently obtained by extraction of the plant material using hydro-alcoholic mixtures with high ethanol content. As this ratio is generally chosen by default and scarcely optimized, we intended to investigate the impact of the hydro-alcoholic composition on extract characteristics such as extraction yield, composition profile in selected compounds, and antioxidant/reducing activity such as Folin-Ciocalteu, DPPH, and ORAC. A theoretical determination of rosmarinic (RA) and carnosic (CA) acid solubilities in ethanol:water mixtures was also performed using COSMO-RS and was confronted to experiments. While the best solubilizing solvent (100% ethanol) was also the best extracting solvent for CA, it was not the case with RA since pure ethanol appeared as a poor solvent compared to 30% ethanol which was optimal. Finally, the best antioxidant activities were obtained with 30% ethanol.

Contributing to urban resilience to floods with neighbourhood design: the case of Am Sandtorkai/Dalmannkai in Hamburg

Abstract: On‐going changes in cities caused by rapid urbanisation and climate change have increased both the flood probability and the severity of flooding. Consequently, there is a need for all cities to adapt to climate and socio‐economic changes by developing new strategies for flood risk management. The following risk paradigm shifts from traditional to more integrated approaches, since one of the main emerging tasks for city managers is the development of resilient cities. The concept of resilience is becoming more and more important, despite the many challenges that interfere with its implementation. The goal of this research is to create knowledge on how to operationalise flood resilience at the neighbourhood level through neighbourhood design. A research approach was used and a qualitative analysis tool, the DS3 model, was developed in order to study a particular neighbourhood of HafenCity, in Hamburg. Results show that design measures involving transportation infrastructure, land use (open public spaces) and buildings have been the main contributions to the flood resilience of the neighbourhood.

Estimation of leaf traits from reflectance measurements: comparison between methods based on vegetation indices and several versions of the PROSPECT model.

Abstract: Leaf biochemical composition corresponds to traits related to the plant state and its functioning. This study puts the emphasis on the main leaf absorbers: chlorophyll a and b ( $$C_{ab}$$ ), carotenoids ( $$C_{c}$$ ), water ( $$C_{w}$$ ) and dry mater ( $$C_{m}$$ ) contents. Two main approaches were used to estimate [ $$C_{ab} ,$$ $$C_{c}$$ , $$C_{w}$$ , $$C_{m}$$ ] in a non-destructive way using spectral measurements. The first one consists in building empirical relationships from experimental datasets using either the raw reflectances or their combination into vegetation indices (VI). The second one relies on the inversion of physically based models of leaf optical properties. Although the first approach is commonly used, the calibration of the empirical relationships is generally conducted over a limited dataset. Consequently, poor predictions may be observed when applying them on cases that are not represented in the training dataset, i.e. when dealing with different species, genotypes or under contrasted environmental conditions. The retrieval performances of the selected VIs were thus compared to the ones of four PROSPECT model versions based on reflectance data acquired at two phenological stages, over six wheat genotypes grown under three different nitrogen fertilizations and two sowing density modalities. Leaf reflectance was measured in the lab with a spectrophotometer equipped with an integrating sphere, the leaf being placed in front of a white Teflon background to increase the sensitivity to leaf biochemical composition. Destructive measurements of [ $$C_{ab} ,$$ $$C_{c}$$ , $$C_{w}$$ , $$C_{m}$$ ] were performed concurrently. The destructive measurements demonstrated that the carotenoid, $$C_{c}$$ , and chlorophyll, $$C_{ab}$$ , contents were strongly correlated (r2 = 0.91). The sum of $$C_{ab}$$ and $$C_{c}$$ , i.e. the total chlorophyllian pigment content, $$C_{abc}$$ , was therefore used in this study. When inverting the PROSPECT model, accounting for the brown pigment content, $$C_{bp}$$ , was necessary when leaves started to senesce. The values of $$C_{abc}$$ and $$C_{w}$$ were well estimated (r2 = 0.81 and r2 = 0.88 respectively) while the dry matter content, $$C_{m}$$ , was poorly estimated (r2 = 0.00). Retrieval of $$C_{w}$$ from PROSPECT versions was only slightly biased, while substantial overestimation of $$C_{abc }$$ was observed. The ranking between estimated values of $$C_{abc}$$ and $$C_{w}$$ from the several PROSPECT versions and that derived using the VIs were similar to the ranking observed over the destructively measured values of $$C_{abc}$$ and $$C_{w}$$ . PROSPECT model inversion and empirical VI approach provide similar retrieval performances and are useful methods to estimate leaf biochemical composition from spectral measurements. However, the PROSPECT model inversion gives potential access to additional traits on surface reflectivity and leaf internal structure. This study suggests that non-destructive estimation of leaf chlorophyll and water contents is a relevant method to provide leaf traits with relatively high throughput.

Assessment of groundwater recharge processes through karst vadose zone by cave percolation monitoring

Abstract: Recharge processes of karst aquifers are difficult to assess given their strong heterogeneity and the poorly known effect of vadose zone on infiltration. However, recharge assessment is crucial for the evaluation of groundwater resources. Moreover, the vulnerability of karst aquifers depends on vadose zone behaviour because it is the place where most contamination takes place. In this work, an in situ experimental approach was performed to identify and quantify flow and storage processes occurring in karst vadose zone. Cave percolation monitoring and dye tracing were used to investigate unsaturated zone hydrological processes. Two flow components (diffuse and quick) were identified and, respectively, account for 66% and 34% of the recharge. Quickflow was found to be the result of bypass phenomenon in vadose zone related to water saturation. We identify the role of epikarst as a shunting area, most of the storage in the vadose zone occurring via the diffuse flow component in low permeability zones. Relationship between rainfall intensity and transit velocity was demonstrated, with 5 times higher velocities for the quick recharge mode than the diffuse mode. Modelling approach with KarstMod software allowed to simulate the hybrid recharge through vadose zone and shows promising chances to properly assess the recharge processes in karst aquifer based on simple physical models.