Search results for "Cycling"
showing 10 items of 516 documents
Synchronie entre l'offre et la demande dans le cycle des nutriments: apprendre des écosystèmes naturels pour construire des agrosystèmes durables
2023
Redesigning agrosystems with more ecological regulations can help feed a growing population, preserve soils for future productivity and reduce environmental impacts. However, guidelines for redesigning agrosystems from natural systems are limited. Reviewing the last knowledge of ecosystem functioning, we outlined four ecological systems synchronizing the supply of soluble nutrients by soil biota to fluctuating plant nutrient demand. This synchrony limits deficiencies and excesses of soluble nutrient, which usually penalize both production and regulating services of agrosystems such as nutrient retention and soil carbon storage. We detail how ecological systems promoting synchrony can be ins…
Legacy effects of contrasting water and N-availability patterns on plantmicrobial response to rewetting
2019
National audience; Introduction. Shifts in the frequency and magnitude of rain events (precipitation regime) associated with climate change may affect plant morphological and physiological strategies as well as soil microbial activity.Objectives. The objective of this study was to determine i) how precipitation history shapes the response dynamics of soil bacterial and fungal communities to rewetting, as well as plant-microbial competition for N, and ii) how the N status of the system may modulate the effect of precipitation regime.Materials & methods. The legacy effects of 12 weeks of contrasting precipitation (frequent or infrequent watering, equal total water input) and N inputs was asse…
Soil carbon dynamics and nutrient cycling
2015
Chapitre 7 Section 2 SPE EcolDur; The quantity of organic carbon in soil and the quantity and type of organic inputs have profound impacts on the dynamics of nutrients. Soil organic matter itself represents a large reservoir of nutrients that are released gradually through the action of soil fauna and microorganisms: this is especially important for the supply of N, P and S to plants, whether agricultural crops or natural vegetation. Organic matter also modifies the behaviour and availability of nutrients through a range of mechanisms including increasing the cation exchange capacity of soil, thus leading to greater retention of positively charged nutrient ions such as Ca, Mg, K, Fe, Zn and…
Nitrogen cycling microbial communities: from diversity to interactions and functions
2019
Soil microorganisms form one of the largest biodiversity reservoirs on earth. They also play essential roles in ecosystem functions such as biogeochemical cycling. However, the importance of microbial community diversity and composition for ecosystem functioning is still debated. A sound understanding of the ecological processes governing the assembly of these communities in the environment is also missing. In this talk, I will give examples of how we addressed these knowledge gaps using nitrogen cycling microorganisms as model functional guilds. Nitrogen is the most limiting nutrient for crop production in agriculture. The nitrogen cycle is also one which was pushed by human activities out…
Showing the Invisible: The Economic Cycle of Stone Tools
2023
This contribution takes place in a broader theme, that of “the invisible economy of recyclable materials”. It aims to illustrate the phenomena of recovery of materials from lithic tools and their consequences. The classification of tools by material, although classic, is not relevant from a technical point of view. The material of a tool, in particular its mechanical properties, is to be taken into consideration in its technical analysis, but it cannot constitute a determining criterion in a classification system. Function should come first, as most functional categories use multiple materials. The most striking example, if one can say so, is that of the striking supports, where one finds, …
Pierres et carrières : réflexions autour de différentes stratégies d’approvisionnement sur les chantiers bourguignons médiévaux
2021
In this paper, we want to discuss the complexity of the mechanisms of medieval building stone supplying based on a diachronically and multidisciplinary inquiry on several Cistercian and ducal study cases. The first results enlighten the constraint caused by land property that limits the builders to a supplying network shaped by domain and law. Thanks to the growing vitality of trade and the arrival of independent stone providers, criteria of selection gradually focus on stone itself. Both global and individual strategies evolve then, reinventing the networks of stone providing and the markets.
Public employees in South-Western Norway using an e-bike or a regular bike for commuting – A cross-sectional comparison on sociodemographic factors, …
2019
Large-scale analyses on the travel behavior of e-bikes are scarce, and current knowledge regarding who the e-bike owners are is inconsistent. Also, commuters represent a relevant user group with an unexploited potential. Therefore, the purpose of the present study was to examine (i) associations between type of bike (e-bike vs. regular bike) with place of residence (county), sociodemographic variables (age, sex, educational level, income and ethnicity) and habitual physical activity level, and (ii) if public employees possessing an e-bike cycle more often and longer distances to work. A cross-sectional survey was conducted in 2017 among 1977 (5.2% of eligible subjects) public employees in S…
Investigating the Viability of Multi-Recycling of Asphalt Mixtures through a Preliminary Binder Level Characterization
2022
The incorporation of reclaimed asphalt (RA) in hot mix asphalt mixtures is widely considered a sustainable solution for road infrastructure development. Under the scope of the circular economy (CE), the multiple recycling capability of RA has to be assessed in order to ensure its performance at each recycling cycle and also its viability with different additives. The performance of asphalt mixtures with RA strongly depends on the type of rejuvenator, binder, and their degree of blending in the mix. For this reason, it is essential to know the properties of the aged binder extracted from RA to better understand its rheological properties and optimal dosage of rejuvenation to design a satisfa…
Toward the Decarbonization of Plastic: Monopolymer Blend of Virgin and Recycled Bio-Based, Biodegradable Polymer.
2022
Decarbonization of plastics is based on two main pillars: bio-based polymers and recycling. Mechanical recycling of biodegradable polymers could improve the social, economic and environmental impact of the use of these materials. In this regard, the aim of this study was to investigate whether concentrations of the same recycled biopolymer could significantly affect the rheological and mechanical properties of biodegradable monopolymer blends. Monopolymer blends are blends made of the same polymers, virgin and recycled. A sample of commercially available biodegradable blend was reprocessed in a single-screw extruder until two extrusion cycles were completed. These samples were exposed to gr…
Concurrent endurance and strength training : neuromuscular, cardiorespiratory and hormonal effects of the exercise order in previously untrained and …
2015
The aim of the present thesis was two-fold. First, to investigate physiological adaptations to concurrent endurance and strength training performed in the same session with different exercise orders (i.e. commencing training with endurance or strength, respectively; E+S vs. S+E) in previously untrained men (n=42) (study 1). Second, to examine physiological adaptations when strength training was always performed immediately after endurance running in the same session (E+S) compared to endurance training alone (E) in recreational endurance runners (n=30) (study 2). In study 1, training consisted of 2 - 3 weekly combined endurance cycling and mixed hypertrophic and maximal strength training se…