Infinite horizon impulse control problem with jumps using doubly reflected BSDEs

Existence results for adapted solutions of infinite horizon doubly reflected backward stochastic differential equations with jumps are established. These results are applied to get the existence of an optimal impulse control strategy for an infinite horizon impulse control problem. The properties of the Snell envelope reduce the problem to the existence of a pair of right continuous left limited processes. Finally, some numerical results are provided

Evaluación del riesgo de contaminación por metales pesados en sedimentos superficiales de la Laguna Sur de Túnez mediante un procedimiento de extracción secuencial

In this study, the total concentrations and chemical forms of heavy metals (Fe, Zn, Pb, Cu, Cr, Cd, and Ni) in surface sediments of the South Lagoon of Tunis located in northeast Tunisia were investigated. Multiple geochemical indices were applied to assess the potential environmental risks. The South Lagoon is a valuable regional resource for fisheries, tourism and aquaculture. Total metal concentrations exhibited significant spatial variation attributed to the principal water circulation direction (east to west). The chemical speciation of Fe, Cr and Ni shows that they were mostly related to the residual fraction (Fe 34.8%, Cr 37.4% and Ni 37.9%), while Pb, Zn, Cu, and Cd were mostly related to the non-residual fraction (labile fraction Pb 89.4%, Zn 26.1%, Cu 71.8% and Cd 84.3%). Pb, Zn, Cu and Cr are of high potential bioavailability. The highest pollution was found on the west side of the lagoon according to the calculated global contamination factors. Besides, individual contamination factors, Pb followed by Zn and Cu, posed the highest risk of contamination. This study shows that, even after dredging, the persistence of low concentrations of some contaminants may cause environmental problems in certain physico-chemical conditions.En este estudio, se investigaron las concentraciones totales y las formas químicas de los metales pesados (Fe, Zn, Pb, Cu, Cr, Cd y Ni) en los sedimentos superficiales de la Laguna Sur de Túnez, ubicada en el noreste de Túnez. Se aplicaron múltiples índices geoquímicos para evaluar los riesgos ambientales potenciales. La Laguna Sur es un valioso recurso regional para la pesca, el turismo y la acuicultura. Las concentraciones totales de metales exhibieron una variación espacial significativa, atribuida a la dirección principal de circulación del agua (Este a Oeste). La especiación química de Fe, Cr y Ni muestra que están esencialmente relacionados con la fracción residual (Fe: 34,8%, Cr: 37,4% y Ni: 37,9%), mientras que Pb, Zn, Cu y Cd se encontraron mayoritariamente en la fracción no residual. -fracción residual (fracción lábil Pb: 89,4%, Zn: 26,1%, Cu: 71,8% y Cd: 84,3%). Estos elementos (Pb, Zn, Cu y Cr) tienen un alto potencial de biodisponibilidad. La mayor contaminación se encontró en el lado oeste de la laguna, según los factores de contaminación global calculados. Además, los factores de contaminación individuales, Pb seguido de Zn y Cu, presentaron el mayor riesgo de contaminación. Este estudio muestra que, incluso después de la operación de dragado, la persistencia de bajas concentraciones de algunos contaminantes puede causar problemas ambientales en determinadas condiciones físico-químicas

Infinite Horizon Impulse Control Problem with Jumps and Continuous Switching Costs

paru au Arab Journal of Mathematical Sciences 2021-01-27International audienceExistence results for adapted solutions of infinite horizon doubly reflected backward stochastic differential equations with jumps are established. These results are applied to get the existence of an optimal impulse control strategy for an infinite horizon impulse control problem. The properties of the Snell envelope reduce the problem to the existence of a pair of right continuous left limited processes. Finally, some numerical results are provided

Assessment of the Trophic Status of the South Lagoon of Tunis (Tunisia, Mediterranean Sea): Geochemical and Statistical Approaches

The trophic status assessment of the South Lagoon of Tunis, a shallow Mediterranean coastal area after its restoration, is addressed herein with respect to its various environmental settings which are taken as indicators of water quality. The lagoon had, in the past, witnessed severe environmental quality issues. To resolve these problems, a large restoration project of the lagoon was undertaken which consisted of dredging the bottom sediments removing areas of water stagnation and improving water circulation. After this restoration work, the lagoon morphology has radically changed. In this paper, we attempt to evaluate the lagoon water’s trophic state to analyze the eutrophication risk after almost 16 years. In order to achieve these purposes, two water quality monitoring campaigns were conducted (July 2013 and February 2014). Natural and anthropogenic factors controlling the nutrient content of the lagoon water have been assessed through both geochemical methods and multivariate statistical tools. The results show that the nutrients are from external sources due to the discharge of municipal and industrial wastewater from the surrounding city of the catchment in the lagoon’s south side. According to the TRIX index, the lagoon remains eutrophic presenting a “poor” water quality, notwithstanding the engineering project due to the high level of nutrients

Bioavailability and Assessment of Metal Contamination in Surface Sediments of Rades-Hamam Lif Coast, around Meliane River (Gulf of Tunis, Tunisia, Mediterranean Sea)

The total concentration and the speciation of heavy metals (Pb, Cd, Cu, Zn, Ni, and Cr) in surface sediments of Rades-Hamam Lif coast were determined, with particular focus on the effect that urban and industrial waste in the Meliane river has on the estuary and coastal surface sediments of the Rades-Hamam Lif coast, off the Mediterranean Sea. Several geochemical indices were applied to assess the risk of contamination and the environmental risks of heavy metals on surface sediments. The total concentrations of these heavy metals are influenced by runoff, industrial, and urban wastewater. The Cd, Pb, Zn, and Ni are affected by anthropogenic sources, especially at the mouth of the Meliane river. The sequential extraction of Cd was presented dominantly in the exchangeable fraction and thus the high potential bioavailability. In contrast, Cr and Cu were mostly bound to the residual fraction indicating their low toxicity and bioavailability. The order of migration and transformation sequence was Cd > Pb > Ni > Zn > Cr > Cu, and the degree of pollution was Cd > Pb > Ni > Zn > Cr > Cu

Post-operative radiotherapy of conjunctival malignancies: A series of 24 cases

Objective: To assess the results of post-operative radiation therapy in the management of incompletely resected conjunctival malignancies. Methods: In this retrospective case series, we reviewed the clinical records of all cases of conjunctival tumors treated with post-operative radiotherapy in the radiation oncology department of Salah Azaïz Institute of Tunis, from January 1990 to December 2015. We focused on clinico-pathological characteristics, treatment modalities and patients’ outcome. Results: Twenty four patients were enrolled in our study: 19 men and 5 women. The mean age of our patients was 54 years (range: 20 to 84). The mean basal diameter of the tumor was 11 mm (range 6 to 20 mm). The mean tumor thickness was 4 mm (range 1 to 15 mm). The most frequent histological type was squamous cell carcinoma in 23 cases. One patient had a malignant conjunctival fibrohistiocytoma. Radiation therapy was post-operative for positive or narrow surgical margins in all cases. Eighteen patients were treated with kilovoltage radiation therapy (KVRT). The mean delivered dose to the tumor bed was 64 Gy (range: 60 to 70 Gy). Four patients were treated with an association of KVRT and Strontium 90 plaque brachytherapy. Two patients were treated only with Strontium 90 plaque brachytherapy (2 fractions of 17 Gy). After a median follow-up of 110 months, 19 patients were alive with no evidence of local recurrence in 17 patients. Two patients had a local recurrence and were referred to surgery. Two patients were lost to follow up. The 5-year relapse free survival rate was 90.9%. Radiation-induced side effects were conjunctivitis, cataract, eye watering and glaucoma. Conclusion: Post-operative radiation therapy allows good local control with acceptable toxicities in conjunctival malignancies. Management of these tumors needs a broad collaboration between ophthalmologists and radiation oncologists, to allow a conservative treatment with the lowest rates of local recurrence

PROYECTO UTICA. INVESTIGACIÓN EN LA CIUDAD FENICIO-PÚNICA. VII INFORME PRELIMINAR DE LA CAMPAÑA DE EXCAVACIÓN DE 2017

Imed Ben Jerbania, José Luis López Castro (directores)Resultado de la campaña llevada a cabo en el yacimiento de Utica en el año 2017Los trabajos de campo y laboratorio han sido financiados con las subvenciones anuales concedidas por el programa de excavaciones arqueológicas en el exterior del Ministerio de Educación, Cultura y Deporte del Gobierno de España (campañas de 2010, 2012, 2014, 2015 y 2016), así como por proyectos de investigación de diferentes organismos concedidos a la Universidad de Almería, para las campañas de 2013 y 2017

Proyecto Útica. Investigación en la ciudad fenicio-púnica: informe preliminar de la campaña de excavación de 2018

Resultado de la campaña llevada a cabo en el yacimiento de Utica en el año 2018Ministerio de Ciencia, Innovación y Universidade