La lagune de Ghar El Melh : Diagnostic écologique et perspectives d'aménagement hydraulique

La lagune de Ghar El Melh, située au Nord de la Tunisie (dans le Golfe de Tunis), est caractérisée par une superficie de 28,5 km2, une faible profondeur et une faible communication avec la mer. Actuellement, sous l'effet des actions anthropiques (les rejets terrestres), elle connaît une dégradation progressive de la qualité de ses eaux et sédiments dont les conséquences sont la chute de la richesse biologique et la réduction des ressources halieutiques de la lagune.Dans ce travail, nous présentons les résultats de l'analyse des caractéristiques physico-chimiques et biologiques des eaux de la lagune. Ces analyses montent bien l'hyper-eutrophisation du milieu caractérisé par de fortes concentrations des eaux en azote total et en phosphore total. Les résultats de simulation du fonctionnement hydrodynamique, que nous avons réalisée à l'aide d'un modèle à 2 dimensions intégré sur la hauteur, montrent une stagnation des eaux dans environ 80% de surface de la lagune qui a fortement amplifié la dégradation de la qualité de l'écosystème. Parmi plusieurs scénarios d'aménagements simulés, nous proposons la création d'une nouvelle communication avec la mer dont la simulation hydrodynamique montre une nette augmentation des échanges d'eau mer-lagune. Nous présentons ensuite un modèle écologique homogène de la lagune de Ghar El Melh qui a été mis au point et calibré en s'appuyant sur les mesures de terrain. Les simulations, avec ce modèle, montrent que l'arrêt total des rejets terrestres et la création d'un nouveau grau réduisent considérablement l'eutrophisation du milieu ce qui conduiraient certainement à une nette amélioration de la production halieutique dans la lagune.The Ghar El Melh lagoon is a Mediterranean water body, situated in Northeastern Tunisia, on the Northwestern side of the Gulf of Tunis. The Ghar El Melh lagoon is a vestigial part of the Utique Sea, and this lagoon was largely open at the time of the Roman invasion. Due to a combination of the shape of the coastline and alluvium deposits from the Medjerda River, this small gulf has become progressively closed from the Utique Sea, causing the lagoon to become progressively shaped to its present morphology. The coastal barrier separating the lagoon from the Mediterranean Sea was interrupted, allowing a permanent hydraulic communication across a local opening. The lagoon has an elliptical shape of approximately 28.5 km2 and an average depth of 0.8 m. Due to human activities within the lagoon itself and in the surrounding area, the lagoon ecosystem has suffered a progressive deterioration. This deterioration has led to a reduction in biodiversity resulting mainly in a decrease in fish resources and production.In order to improve the water quality of the lagoon for ecological and economical purposes, a diagnostic survey was carried out to characterize the present site conditions and to provide data for calibration of hydrodynamic and ecological models. The main results of the annual survey of biotic and non-biotic parameters demonstrated the existence of zones within the lagoon, with some seasonal variation. Thus, a decreasing biotic and non-biotic gradient was measured from the area of the lagoon under marine influence towards the bottom of the lagoon, under the continental and anthropogenic influence of the west side. The lagoon could be considered hypereutrophic with an annual average concentration of total phosphorus of 350 mg/m3. In order to conceptualize and optimise hydraulic structures for water quality improvement in the lagoon, a numerical model of the velocity fields (depth averaged) and water depth was used. The hydrodynamic model used was bi-dimensional, adapted for use in shallow lagoons. After model calibration using in-situ measurements, simulations were carried out to analyse the present hydrodynamic condition of the lagoon. Several stagnation zones were detected, which contributed to the altered water quality that was observed. Several management practices were proposed and simulated, aiming to control and improve the internal circulation and water exchange between the lagoon and the Mediterranean Sea. The main goal of these simulations was to improve water mobility inside the lagoon, and thus improve the water quality. The proposed hydraulic development measures consisted mainly of the creation of a new hydraulic communication in the south-eastern area of the lagoon, by dredging the south part of the lake or by channel creation in front of the new communication, reaching the stagnation zones of the lagoon. The impact assessment of the proposed development was verified with simulations using the bi-dimensional hydrodynamic model.An ecological model based on nitrogen and phosphorus cycling, was also developed for Ghar El Melh lagoon. It took into account one ecological compartment, the macro algae, that included Cladophora sp., Ulva sp. and Enteromorpha sp. Algae (A), inorganic nitrogen (NA), inorganic phosphorus (PA), organic nitrogen (NEorg) and organic phosphorus (PEorg), were the main variables of this model. After calibration of the model, a 10-yr simulation showed that all variables demonstrated a steady behaviour and that the lagoon eutrophication level remained. Model sensitivity analysis allowed the choice of some restoration scenarios and the prediction of their impacts on the ecological behaviour of the ecosystem. The simulations showed that wastewater load deviation combined with an increase in the sea-lagoon water exchange, instead of a decrease of nutrient diffusion from the sediments, led to a substantial decrease in the eutrophication level of the lagoon. Indeed, the annual average nutrient concentrations decreased from 270 to 60 mg/m3 for total nitrogen and from 350 to 20 mg/m3 for total phosphorus in the Ghar El Melh lagoon

Heat and fluid flow in a scraped-surface heat exchanger containing a fluid with temperature-dependent viscosity

Scraped-surface heat exchangers (SSHEs) are extensively used in a wide variety of industrial settings where the continuous processing of fluids and fluid-like materials is involved. The steady non-isothermal flow of a Newtonian fluid with temperature-dependent viscosity in a narrow-gap SSHE when a constant temperature difference is imposed across the gap between the rotor and the stator is investigated. The mathematical model is formulated and the exact analytical solutions for the heat and fluid flow of a fluid with a general dependence of viscosity on temperature for a general blade shape are obtained. These solutions are then presented for the specific case of an exponential dependence of viscosity on temperature. Asymptotic methods are employed to investigate the behaviour of the solutions in several special limiting geometries and in the limits of weak and strong thermoviscosity. In particular, in the limit of strong thermoviscosity (i.e., strong heating or cooling and/or strong dependence of viscosity on temperature) the transverse and axial velocities become uniform in the bulk of the flow with boundary layers forming either just below the blade and just below the stationary upper wall or just above the blade and just above the moving lower wall. Results are presented for the most realistic case of a linear blade which illustrate the effect of varying the thermoviscosity of the fluid and the geometry of the SSHE on the flow

Change, stress and sustainability: aquatic ecosystem resilience in North Africa

Summary report of a workshop held at the Institute Scientifique, University Mohammed V, Rabat, Morocco, 2-5th December 1998. Cassarina report no. 4

EMPREGO DE FIBRAS DE TRIGO E SOJA NA ELABORAÇÃO DE MORTADELAS

A mortadela está entre os produtos cárneos mais consumidos no Brasil. A substituição parcial de gordura animal por fibras vegetais na elaboração de mortadelas foi o objetivo do presente estudo, uma vez que as fibras possuem valor nutricional de interesse para a saúde humana, além de possuírem baixo custo. A gordura por sua vez é importante na formulação, pois atua na formação da emulsão. No desenvolvimento da pesquisa foram utilizadas três formulações de mortadela, sendo elas respectivamente: padrão (A), com substituição parcial de gordura por fibra de trigo (B) e com substituição parcial de gordura por soja (C). O estudo buscou atender o Regulamento Técnico de Identidade e Qualidade de Mortadela do Ministério da Agricultura, Pecuária e Abastecimento (MAPA), e as mortadelas foram avaliadas físico-químicamente. Os resultados médios obtidos nas análises foram comparados aos citados pelo MAPA foram, respectivamente, para a mortadela A, B e C: 60,4%, 59,3% e 61,1% de umidade; 5,5%, 5,3% e 4,5% de cinzas; 15,5%, 14,1% e 13,5% de gordura; 1,52%, 3,5% e 4,2% de fibras e 16,32%, 17,2% e 15,9% de proteína. Estes resultados demonstram a viabilidade tecnológica para elaboração de novos produtos cárneos

Spatial distribution of micrometre‐scale porosity and permeability across the damage zone of a reverse‐reactivated normal fault in a tight sandstone : Insights from the Otway Basin, SE Australia

This research forms part of a PhD project supported by the Australian Research Council [Discovery Project DP160101158] and through an Australian Government Research Training Program Scholarship. Dave Healy acknowledges the support of the Natural Environment Research Council (NERC, UK) through the award NE/N003063/1 ‘Quantifying the Anisotropy of Permeability in Stressed Rock’. This study was also funded by scholarships from the Petroleum Exploration Society of Australia and the Australian Petroleum Production and Exploration Association. We thank Gordon Holm for preparing thin sections and Colin Taylor for carrying out particle size measurements and mercury injection capillary pressure analyses. Aoife McFadden and David Kelsey from Adelaide Microscopy, Braden Morgan, and Sophie Harland are acknowledged for their assistance with laboratory work. Field assistants James Hall, Rowan Hansberry, and Lachlan Furness are also gratefully acknowledged for their assistance with sample collection. Discussions with Ian Duddy on the mineralogy of the Eumeralla Formation are also greatly appreciated. This forms TRaX record 416.Peer reviewedPublisher PD

PRODUÇÃO E CARACTERIZAÇÃO FISÍCO-QUÍMICA DE FARINHAS DE MANDARINA VERDE ORGÂNICA (Citrus rediculata)

Para melhorar a qualidade demandarinasdo mercado in natura, a técnica do raleio manual é utilizada pelos citricultores, sendo necessário ralear 60 a 80% dos frutos.Propôs-se elaborar farinhas a partir da casca e da polpa de mandarinas verdes orgânicas oriundas do raleio, caracterizando sua composição proximal a fim de introduzi-las na alimentação humana.As farinhas foram obtidas pela trituração úmida, lavagem, secagem e trituração seca do resíduo desidratado das mandarinas. As análisesdas farinhas de polpa (FP) e de polpa com casca (FPC) de mandarina verde orgânica foram realizadas segundo as metodologias preconizadas pelo Instituto Adolfo Lutz (2008). A umidade (FP=3,78%; FPC=3,03%), cinzas (FP=2,19%; FPC=2,46%) e proteínas (FP=15,83%; FPC=11,38%) das farinhas ficaram dentro do permitido pela legislação brasileira para farinha de trigo comum e/ou integral; apresentaram um teor de fibra bruta alto (FP=18,45%; FPC=17,25%), baixo teor de gorduras (FP=1,25%; FPC=0,85%), boa quantidade de carboidratos (FP=58,14%; FPC=66,25%) e menos calorias (FP=307,25 Kcal/100g; FPC=318,30 Kcal/100g) que a farinha de trigo comum. As farinhas de mandarina verde orgânica são uma alternativa para o enriquecimento de produtos de panificação, agregando não só valor nutricional como minimizando o desperdício de resíduos

PRODUÇÃO DE UMA FARINHA DE ALBEDO DE LARANJA COMO FORMA DE APROVEITAMENTO DE RESÍDUO

O Brasil é um dos maiores produtores de suco de laranja e exporta cerca de 70% da sua produção. Durante o processamento do suco de laranja são gerados subprodutos, como o bagaço denominado também de albedo. Visando a diversificação tecnológica, este trabalho possui como objetivo a elaboração de uma farinha a partir de um subproduto da indústria de sucos, que possa ser utilizada como enriquecimento nutricional em formulações de produtos de panificação. A farinha foi obtida pela trituração úmida, lavagem, secagem e trituração seca do resíduo desidratado das laranjas. As análises físico-químicas da farinha de albedo de laranja foram realizadas segundo as metodologias preconizadas pelo Instituto Adolfo Lutz (2008). A umidade (11,75%) da farinha ficou dentro do máximo permitido pela legislação brasileira; apresentou um baixo teor de gorduras (0,42%) e calorias em torno de 18% a menos que a farinha de trigo. A fibra bruta da farinha de albedo da laranja (16,20%) é cinco vezes maior, em comparação a uma farinha tradicional de trigo (3,2%), podendo ser considerada um ingrediente funcional. A farinha de albedo de laranja é uma excelente alternativa para enriquecimento de produtos de panificação, agregando não só valor econômico como valor nutricional, com considerável teor de fibras

ÁCIDO LINOLEICO CONJUGADO: UMA BREVE REVISÃO

O ácido linoleico conjugado (CLA) é um ácido graxo poli-insaturado natural, encontrado principalmente na gordura do leite e na carne de animais ruminantes. Seus isômeros geométricos e de posição c9t11 e t10c12 vêm despertando interesse, uma vez que o primeiro é considerado um agente anticarcinogênico natural e o segundo, um repartidor de nutrientes efetivo. Pesquisas relacionam o CLA a outros efeitos positivos à saúde como a redução de aterosclerose, prevenção e tratamento do diabetes mellitus, estimulação do sistema imunológico, redução da pressão arterial e da gordura corporal com aumento da massa magra. Apresenta propriedade hipocolesteronica além de atuar como poderoso antioxidante. Assim, este trabalho de revisão tem por objetivo o enfoque na produção de CLA, seus benefícios à saúde, bem como os métodos analíticos de quantificação do mesmo em alimentos

Modelling credit spreads with time volatility, skewness, and kurtosis

This paper seeks to identify the macroeconomic and financial factors that drive credit spreads on bond indices in the US credit market. To overcome the idiosyncratic nature of credit spread data reflected in time varying volatility, skewness and thick tails, it proposes asymmetric GARCH models with alternative probability density functions. The results show that credit spread changes are mainly explained by the interest rate and interest rate volatility, the slope of the yield curve, stock market returns and volatility, the state of liquidity in the corporate bond market and, a heretofore overlooked variable, the foreign exchange rate. They also confirm that the asymmetric GARCH models and Student-t distributions are systematically superior to the conventional GARCH model and the normal distribution in in-sample and out-of-sample testing

High resolution human leukocyte antigen (HLA) class I and class II allele typing in Mexican mestizo women with sporadic breast cancer: case-control study

<p>Abstract</p> <p>Background</p> <p>The development of breast cancer is multifactorial. Hormonal, environmental factors and genetic predisposition, among others, could interact in the presentation of breast carcinoma. Human leukocyte antigen (HLA) alleles play an important role in immunity (cellular immunity) and may be important genetic traits. HLAAllele-specific interaction has not been well established. Recently, several studies had been conducted in order to do so, but the results are controversial and in some instances contradictory.</p> <p>Methods</p> <p>We designed a case-control study to quantify the association of HLA class I and II genes and breast cancer. HLA typing was performed by high resolution sequence-specific oligotyping after DNA amplification (PCR-SSOP) of 100 breast cancer Mexican mestizo patients and 99 matched healthy controls.</p> <p>Results</p> <p>HLA-A frequencies that we were able to observe that there was no difference between both groups from the statistical viewpoint. HLA-B*1501 was found three times more common in the case group (OR, 3.714; <it>p </it>= 0.031). HLA-Cw is not a marker neither for risk, nor protection for the disease, because we did not find significant statistical differences between the two groups. DRB1*1301, which is expressed in seven cases and in only one control, observing an risk increase of up to seven times and DRB1*1602, which behaves similarly in being present solely in the cases (OR, 16.701; 95% CI, 0.947 – 294.670). DQ*0301-allele expression, which is much more common in the control group and could be protective for the presentation of the disease (OR, 0.078; 95% CI, 0.027–0.223, <it>p </it>= 0.00001).</p> <p>Conclusion</p> <p>Our results reveal the role of the MHC genes in the pathophysiology of breast cancer, suggesting that in the development of breast cancer exists a disorder of immune regulation. The triggering factor seems to be restricted to certain ethnic groups and certain geographical regions since the relevant MHC alleles are highly diverse. This is the first study in Mexican population where high resolutions HLA typing has been performed in order to try to establish an association with malignancy.</p