Optimal Soil Management and Environmental Policy

This paper studies the effects of environmental policy on the farmers soil optimal management. We consider a dynamic economic model of soil erosion where the intensity use of inputs allows the farmer to control soil losses. Therefore, inputs use induces a pollution which is accentuated by the soil fragility. We show, at the steady state, that environmental tax induces a more conservative farmer behavior for soil, but in some cases it can exacerbates pollution. These effects can be moderated when farmer introduces abatement activity.soil erosion, pollution, environmental policy, optimal soil conservation, abatement activities, Environmental Economics and Policy, Q12, Q24, Q28, Q52, H23,

Optimal Soil Management and Environmental Policy

This paper studies the effects of environmental policy on the farmer’s soil optimal management. We consider a dynamic economic model of soil erosion where the intensity use of inputs allows the farmer to control soil losses. Therefore, inputs use induces a pollution which is accentuated by the soil fragility. We show, at the steady state, that the environmental tax induces a more conservative farmer behavior for soil, but in some cases it can exacerbate pollution. These effects can be moderated when farmers introduce abatement activity.Soil erosion, Pollution, Environmental policy, Optimal soil conservation, Abatement activities

Energy loss and inelastic diffraction of fast atoms at grazing incidence

The diffraction of fast atoms at grazing incidence on crystal surfaces (GIFAD) was first interpreted only in terms of elastic diffraction from a perfectly periodic rigid surface with atoms fixed at equilibrium position. Recently, a new approach have been proposed, referred here as the quantum binary collision model (QBCM). The QBCM takes into account both the elastic and inelastic momentum transfer via the Lamb-Dicke probability. It suggests that the shape of the inelastic diffraction profiles are log-normal distributions with a variance proportional to the nuclear energy loss deposited on the surface. For keV Neon atoms impinging the LiF surface, the predictions of the QBCM in its analytic version are compared with numerical trajectory simulations. Some of the assumptions such as the planar continuous form, the possibility to neglect the role of lithium atoms and the influence of temperature are investigated. A specific energy loss dependence $\Delta E\propto\theta^7$ is identified in the quasi-elastic regime merging progressively to the classical onset $\Delta E\propto\theta^3$. The ratio of these two predictions highlight the role of quantum effects in the energy loss.Comment: 9 pages 8 figures paper prepared for IISC-2

On some problems of the Tunisian lexical stock

This article is devoted to some problems of the Tunisian lexicon from the point of view of contact between the Tunisian Arabic language community and other language communities. The terms Tunisian Arabic language community, General Tunisian Arabic and Pan-Arabic language community are first defined. Contacts between the Tunisian Arabic language community and other language communities are discussed while part of the lexicon stemming from Arabic and French is analyzed.This article is devoted to some problems of the Tunisian lexicon from the point of view of contact between the Tunisian Arabic language community and other language communities. The terms Tunisian Arabic language community, General Tunisian Arabic and Pan-Arabic language community are first defined. Contacts between the Tunisian Arabic language community and other language communities are discussed while part of the lexicon stemming from Arabic and French is analyzed

Organisation de la filière paysage en milieu urbain

Le paysage est défini par la Convention européenne du paysage comme « une partie de territoire telle que perçue par les populations, dont le caractère résulte de l\u27action de facteurs naturels et/ou humains et de leurs interrelations ». C’est, à maints égards, une construction politique, culturelle et économique des rapports qu’entretiennent les sociétés humaines à l’espace.Quels sont les éléments qui fondent l’organisation sociale de l’espace ? Quels sont les mécanismes à l’origine de son évolution ? Qu’est-ce qui rassemble les individus, malgré la divergence de leurs intérêts ? L’approche économique du paysage s’est développée ces dernières années pour répondre à ces questions et à bien d’autres. Cet ouvrage collectif réunit les résultats récents de la recherche sur ce thèm

Chestnut rots: disease incidence and molecular identification of causal agents

Dupla diplomação com a Université Libre de TunisChestnut fruits are popular fruits commercialized as fresh or processed ready to be used as products. Because of its high moisture and suitable nutrient content, the chestnut kernel has the potential to support the growth of a wide spectrum of spoilage fungi. The major postharvest problems associated with stored chestnut fruits are rots, which result in major losses in fruit quality. Although the empirical knowledge determines a high level of rot in Portuguese chestnuts, there are no scientific studies on the incidence and severity of the problem, and the causal agents have never been identified. This knowledge is of the utmost importance and urgency for industry and retailers to correctly address the issue, in an effort to reduce yield loss due to rot. The aims of this work were: i) to determine the incidence, abundance and diversity of rots in three chestnut varieties of Trás-os-Montes – Judia, Longal and Martaínha – at different postharvest stages of storage and processing, and ii) to identify the main potential agents of rots. For this purpose chestnuts were internally and externally inspected for presence of damages, infestation and infection. Samples from variety Martaínha were identified as the most resistant to fungal growth, while samples from variety Longal were less resistant to fungal growth and infestation. A high diversity of species has been molecularly identified by sequencing the ITS region: 37 different species belonging to 16 genera. The dominant fungal species found with high frequency were Mucor racemosus f. sphaerosporus (24.2% of frequency), Penicillium brevicompactum (16.7%) and Penicillium thomii (causal agents of green rot; 13.9%), Ciboria batschiana (the causal agent of black rot; 10.6%) and Botrytis cinerea (the causal agent of grey rot10.6%). Gnomoniopsis smithogilvyi, the causal agent of brown rot, was also identified with a frequency of 6.4%. The results show that the causal agents of various chestnut rots already identified in other countries are also present in Portuguese nuts. Studies must follow with the aim of developing control measures against the identified rot-causing fungi.A castanha é um fruto popular comercializado e consumido tanto em fresco como processado. Devido à sua elevada humidade e teor de nutrientes, a castanha tem o potencial de permitir o crescimento de um amplo espectro de fungos de deterioração. Os principais problemas pós-colheita associados à castanha armazenada são as podridões, que resultam em grandes perdas na qualidade dos frutos. Embora o conhecimento empírico evidencie um alto nível de podridão nas castanhas portuguesas, não existem estudos científicos sobre a incidência e gravidade do problema, e os agentes causais nunca foram identificados. Esse conhecimento é da maior importância e urgência para a indústria e os comerciantes resolverem o problema adequadamente, no sentido de reduzirem as perdas de rendimento devido à podridão. Os objetivos deste trabalho foram: i) determinar a incidência, abundância e diversidade de podridões em três variedades de castanha de Trás-os-Montes - Judia, Longal e Martaínha - em diferentes estágios pós-colheita de armazenamento e processamento; e ii) identificar os principais agentes causais das podridões. Para esse fim, as castanhas foram inspecionadas interna e externamente quanto à presença de danos, infestações e infeções. Amostras da variedade Martaínha foram identificadas como as mais resistentes ao crescimento de fungos, enquanto amostras da variedade Longal foram menos resistentes ao crescimento e infestação de fungos. Uma alta diversidade de espécies de fungos foi identificada molecularmente através da região ITS: 37 espécies diferentes pertencentes a 16 géneros. As espécies dominantes encontradas com alta frequência foram Mucor racemosus f. sphaerosporus (24.2% de frequência), Penicillium brevicompactum (16.7%) e Penicillium thomii (13.9%) (agentes causais de podridão verde), Ciboria batschiana (agente causal da podridão negra; 10.6%) e Botrytis cinerea (agente causal da podridão cinzenta; 10.6%). Gnomoniopsis smithogilvyi, agente causal da podridão castanha, também foi identificado, com frequência de 6.4%. Estes resultados mostram que os principais agentes causais das podridões da castanha se encontram também nas castanhas portuguesas. Estão em curso estudos para desenvolvimento de métodos de controlo des fungos nas castanhas.This work was developed under the scope of the project “ValorCast - Valorização da castanha e otimização da sua comercialização”, ref. PDR2020-101-032030. Funded by Fundo Europeu Agrícola de Desenvolvimento Rural (FEADER) and Portuguese Government, under the scope of Ação 1.1 «Grupos Operacionais», Medida 1. «Inovação», PDR 2020 – Programa de Desenvolvimento Rural do Continente

Stick-slip waves between elastic and rigid half-spaces

International audienceThe construction of an analytic solution of the problem of stick-slip waves crossing the interface between an elastic half-space and a tigid one under unilateral contact and Coulomb friction is considered. The method of solution is based on the analytic continuation method of Radok's complex potentials within the framework of steady elastodynamic problems. The governing equations combined with the boundary conditions are reduced to a Riemann-Hilbert problem with discontinuous coefficient, and closed-form expressions of the solution are derived. It is found that the existence of solutions depends on the additional velocity, which is related to the longitudinal elongation. If this velocity is ignored, there is no solution, if not, it is possible to construct weakly singular solutions satisfying all stick-slip conditions except over a narrow zone where the waves exhibit a crack-like behaviour

Dendritic Cell-Based Graft Tolerance

It has recently been demonstrated that mouse and human dendritic cells (DCs) can produce IL-2 after activation. However the role of the IL2/IL2R pathway in DC functions has not yet been fully elucidated. The results presented in this study provide several new insights into the role of this pathway in DCs. We report that stimulation of human monocyte-derived DCs with LPS strongly upregulated CD25 (α chain of the IL2R) expression. In additon, by using a humanized monoclonal antibody against CD25, we demonstrated that the IL2 signalling in DC upregulated both IL-12 and γIFN production but decreased IL10 synthesis. We also found that LPS-matured DCs produced IL2. Taken together, these results suggest that IL-2 actively contributes to the DC activation through an autocrine pathway. Furthermore, our results indicate that the IL2 pathway in DC is involved in the development of T-helper priming ability and in the upregulation of surface markers characteristic of a “mature” phenotype. This study therefore provide new molecular clues regarding the split between these two phenomena and unravel new mechanisms of action of anti-CD25 monoclonal antibodies that may contribute to their action in several human immunological disorders such as autoimmune diseases and acute allograft rejection