Système alimentaire | EPFL Graph Search

vignette|redresse=1.8|Diagramme représentant la transformation du système alimentaire conventionnel en système alimentaire durable. Un système alimentaire est un ensemble de processus concernant la nutrition, l'alimentation, la santé, le développement communautaire et l'agriculture. Il comprend tous les processus et infrastructures urbaines impliqués dans l'alimentation d'une population : culture, récolte, transformation, emballage, transport, commercialisation, consommation, distribution alimentaire et élimination des aliments et des articles liés à l'alimentation. Il comprend également les entrées nécessaires et les sorties générées à chacune de ces étapes. Un système alimentaire fonctionne dans des contextes sociaux, politiques, économiques et environnementaux. Il nécessite également des ressources humaines pour fournir la main-d'œuvre, et assurer la recherche et l'éducation. Les systèmes alimentaires sont conventionnels ou alternatifs selon leur modèle de durée de conservation des

Computational Approaches for Studying Dietary Behaviors with Digital Traces

Kristina Gligoric

Human nutrition and dietary habits shape our health, daily life, societies, the environment, and life on earth in general. However, it remains challenging to understand and attempt to change dietary behaviors using traditional methods due to measurement and causal identification challenges.In this thesis, we contribute computational and causal approaches leveraging large-scale passively sensed digital traces to shed new light on our dietary behaviors and derive novel scientific insights. We study dietary behaviors in two types of contexts: campus-wide and worldwide. Based on digital traces capturing behaviors of tens of thousands of people on campus and millions of internet users, we develop observational study designs that enable the isolation of causal effects of implicit behavioral interventions, including forming social ties, being exposed to the food choice of others, and stay-at-home interventions. The thesis is organized into three parts.The first part presents studies based on situated on-campus food purchase logs. In the first study, we show how, when a person acquires a new eating partner on campus, the healthiness of their food choice shifts significantly in the direction of their new eating partner's dietary patterns. In the second study, we identify purchasing mimicry, i.e., copying the food choices of others in the purchasing queue, as a specific behavioral mechanism for how similarities in dietary behaviors between individuals occur on campus. The second part of the thesis leverages online information-seeking traces (Google search query logs). Studying worldwide dietary behaviors, we identify and describe global shifts in dietary interests during the first wave of the COVID-19 pandemic, larger and longer-lasting than the typical changes during the end-of-year holidays in Western countries.In the third part, we critically investigate the limits to how much computational approaches can reveal about dietary behaviors in the general population. We contribute a framework for reasoning about biases of digital traces and present a case study of food consumption in Switzerland. The bias estimates derived in the case study imply that researchers should aim to establish evidence of validity before relying on social media and tracking apps---two frequently used digital traces---as proxies for true food consumption in the general population.The novel scientific findings and methodological advances presented here contribute to the existing knowledge about human dietary behaviors and inform the design of future food systems, policies, and behavioral interventions.

EPFL2022

Transition of the Swiss Phosphorus System towards a Circular Economy — Part 1: Current State and Historical Developments

Claudia Rebeca Binder Signer, Jonas Ramon Mehr

Current phosphorus (P) use in European countries is highly dependent on mineral P imports and not sustainably managed. In order to identify and implement measures for sustainable P management, a comprehensive understanding of national P flows and stocks and their temporal dynamics is essential. We conduct a substance flow analysis (SFA) of the Swiss P system of the year 2015, and study the dynamics of the national P system by looking into its development since 1989. Furthermore, we investigate how political-legislative interventions affected the P system during this period. The results show that between 1989 and 2015, the P efficiency in Swiss agriculture increased from 59% to 94%, mainly due to a considerable reduction of fertilization in the agricultural subsystem. At the same time, Switzerland's P import dependency decreased from 33% to 24% between 1989 and 2002 because of a reduction of mineral fertilizer import and use. Between 2002 and 2015, the import dependency stagnated because further improvements in P use efficiency in agriculture were outweighed by a decrease of P recycling and an increase of P losses in the waste management system. By embedding these temporal dynamics in their political-legislative context, we found that top-down interventions such as incentives for a balanced nutrient budget in agriculture, restrictions of the use of animal by-products in the agri-food system or the ban of direct sewage sludge recycling in agriculture significantly affected and shaped the national P system. Our analysis provides profound quantitative and qualitative insights into past and present P management in Switzerland and is followed by part 2 of the paper, where we analyze possible future pathways of P management.

2018

Comparative assessment of selected sugarcane biorefinery-centered systems in Brazil: A multi-criteria method based on sustainability indicators

Edgard Gnansounou, Catarina Marciano Alves, Elia Mercedes Ruiz Pachon, Pavel Vaskan

This work proposes a new sustainability assessment framework aiming to compare selected options of biorefineries subject to provide the same services to a community. At this end, a concept of biorefinery-centered system helps to develop a joint resources and policy-oriented comparison. When an option of biorefinery cannot provide the given amounts of certain services from its own production, it complements its supply portfolio by purchasing the lacking amounts from complementary and conventional production systems. The proposed sustainability assessment framework includes a multi-criteria method used to compare the selected biorefinery options resulting in identifying their respective weaknesses and strengths against categories of criteria. Finally, the methodology helps finding the non-dominated option. Application to selected sugarcane-based biorefineries shows promising results that match with those obtained in a previous work. However, the new methodology allows extended and richer analyses. (C) 2017 Elsevier Ltd. All rights reserved.

Elsevier2017

Computational Approaches for Studying Dietary Behaviors with Digital Traces

Kristina Gligoric

EPFL2022