Les profits " excessifs " des commerçants de fruits et légumes en Algérie : réalité ou préjugé infondé ? Le cas de la tomate primeur à Biskra

Dans les pays en développement, les agriculteurs dépendent, pour la commercialisation de leurs produits, d'un réseau complexe d'intermédiaires, souvent accusés de réaliser des profits excessifs. C'est le cas en Algérie, où ce discours est relayé par les agriculteurs et les consommateurs. Est-ce une réalité ou un préjugé infondé ? Cette étude se focalise sur la filière tomate primeur d'El Ghrous (wilaya de Biskra, dans le Sahara algérien), dont la production a connu un développement fulgurant ces 20 dernières années. Dans un premier temps, les facteurs, endogènes et exogènes, déterminant la formation des prix sont identifiés. Dans un second temps, la répartition de la valeur ajoutée le long de la filière est analysée à travers le calcul du délai de récupération des fonds investis et une comparaison des taux de marge des acteurs. Les résultats montrent que, pour cette filière, les intermédiaires ne réalisent pas de profits excessifs au détriment des agriculteurs. Le marché de gros d'El Ghrous est efficace, ce qui constitue un atout majeur pour le développement des cultures maraîchères dans la région. (Résumé d'auteur

LA LUTTE CONTRE LA DESERTIFICATION DES PARCOURS STEPPIQUES : L'APPROCHE DU DEVELOPPEMENT AGRO-PASTORAL INTEGRE

N° ISBN - 978-2-7380-1284-5International audienceThe Algerian steppe suffered for several decades a serious problem of desertification, under the combined effect of anthropogenic and natural factors. This desertification means the installation of a "semi-desert" ecosystem in place of the steppic ecosystem which used to support an ancestral socio-economic system based on pastoral livestock. The scarcity of forage resources, the decline of farming activity and the degradation of living conditions of steppe inhabitants are among problems posed by desertification on nearly 80% of agricultural land in the country. The fight against this phenomenon constitutes a strategic challenge for Algeria for which significant public funds have been committed. The mixed results of these efforts prove the ineffectiveness of the adopted approaches and methods. Exploring new approaches to analyze the problem of desertification and consider new ways of thinking and implementing the fight against this phenomenon and more generally for sustainable development of the steppe, is required. This paper shows the first results of a project on participatory action research which is testing a bottom up and integrated approach to fight against desertification based on the reorientation of the agro pastoral systems towards a logic that attempts to reconcile valorisation and sustainable preservation of rangelands natural resources. Five integrated models of agro pastoral production systems have been designed with the active participation of rural development actors, including agro pastoralists. These models are currently being tested with a group of agro-pastoralists experimenters

Contrat et confiance pour la gestion des risques de defaillances dans les transactions de financement informel dans le secteur agricole en Algerie

Penser et mettre en oeuvre de nouveaux mécanismes de gestion des risques de défaillance dans les transactions de financement agricole, qui soient plus efficaces et moins contraignants pour les agriculteurs, constituent l’un des défis majeurs du développement des systèmes financiers ruraux dans les pays en développement. L’étude du financement informel, très fréquent dans ces pays, peut alimenter la réflexion sur ce type d’innovations. Cet article présente les résultats d’une étude empirique sur les mécanismes de gestion des risques de défaillance dans les transactions d’association de production, l’une des transactions de financement informel les plus répandues dans le secteur agricole en Algérie. Les risques sont gérés, dans ces transactions, à travers des mécanismes contractuels et la confiance. L'analyse du fonctionnement de ces mécanismes démontre qu'une conception et une gestion adéquate des relations contractuelles est précisément la clé de l'émergence de la confiance qui une fois acquise, contribue au bon fonctionnement et à l’efficience des transactions de financement informel.MOTS CLES: Financement informel, association de production, gestion de risque de défaillance, confiance, contrat

Transformer-based Self-supervised Multimodal Representation Learning for Wearable Emotion Recognition

Recently, wearable emotion recognition based on peripheral physiological signals has drawn massive attention due to its less invasive nature and its applicability in real-life scenarios. However, how to effectively fuse multimodal data remains a challenging problem. Moreover, traditional fully-supervised based approaches suffer from overfitting given limited labeled data. To address the above issues, we propose a novel self-supervised learning (SSL) framework for wearable emotion recognition, where efficient multimodal fusion is realized with temporal convolution-based modality-specific encoders and a transformer-based shared encoder, capturing both intra-modal and inter-modal correlations. Extensive unlabeled data is automatically assigned labels by five signal transforms, and the proposed SSL model is pre-trained with signal transformation recognition as a pretext task, allowing the extraction of generalized multimodal representations for emotion-related downstream tasks. For evaluation, the proposed SSL model was first pre-trained on a large-scale self-collected physiological dataset and the resulting encoder was subsequently frozen or fine-tuned on three public supervised emotion recognition datasets. Ultimately, our SSL-based method achieved state-of-the-art results in various emotion classification tasks. Meanwhile, the proposed model proved to be more accurate and robust compared to fully-supervised methods on low data regimes.Comment: Accepted IEEE Transactions On Affective Computin

Fusion of Physiological and Behavioural Signals on SPD Manifolds with Application to Stress and Pain Detection

Existing multimodal stress/pain recognition approaches generally extract features from different modalities independently and thus ignore cross-modality correlations. This paper proposes a novel geometric framework for multimodal stress/pain detection utilizing Symmetric Positive Definite (SPD) matrices as a representation that incorporates the correlation relationship of physiological and behavioural signals from covariance and cross-covariance. Considering the non-linearity of the Riemannian manifold of SPD matrices, well-known machine learning techniques are not suited to classify these matrices. Therefore, a tangent space mapping method is adopted to map the derived SPD matrix sequences to the vector sequences in the tangent space where the LSTM-based network can be applied for classification. The proposed framework has been evaluated on two public multimodal datasets, achieving both the state-of-the-art results for stress and pain detection tasks.Comment: International Conference on Systems, Man, and Cybernetics, IEEE SMC 2022, October 9-12, 202

The role of citizenship values and civic education for the development of social skills at secondary schools

This paper seeks to empirically investigate the question of citizenship values and civic education in Moroccan secondary schools. It undertakes a comparative study based on an interdisciplinary approach in order to measure the presence of these values in Physics and English educational practices. The study is realized via a questionnaire administered to and interviews conducted with practicing teachers of Physics and English throughout different schools in Morocco. Data collection and analysis were performed by adopting a statistical descriptive method. The study is accomplished by targeting a number that reached 84 teachers in both disciplines. Our results demonstrate that teachers have different conceptions concerning values and they show less interest in implementing those values in the teaching/learning operation. Physics teachers believe that Physics as a purely scientific discipline cannot lead itself to integrating citizenship values and they can be integrated only in Humanities disciplines. Furthermore, we find that teachers not only never benefited from a basic or in-service training but also professional interaction among them about those values is very lacking. Besides, a considerable number of respondents agree that citizenship values are decreasing among learners. In this sense, majority of respondents suggest that training, motivation and well-prepared institutional strategies are fundamental prerequisites to overcome those difficulties.

Gyro-Chirality Effect of Bianisotropic Substrate On the operational of Rectangular Microstrip Patch Antenna

yesIn this paper, the gyrotropic bi-anisotropy of the chiral medium in substrate constitutive parameters (ξc and ηc) of a rectangular microstrip patch antenna is introduced in order to observe its effects on the complex resonant frequency, half-power bandwidth and input impedance. Numerical calculations and analysis based on the dominant mode are carried out to show that the latter is directly related to the former. This paper is based on the Moment Method as full-wave spectral domain approach using sinusoidal basis functions. Two new results, namely the appearance of the difference (ξc-ηc) and sum (ξc+ηc) of the two magneto-electric elements are obtained in the electric transverse components and Green tensor expressions, respectively. These new results can be considered as a generalisation form of the previously published work