On Solving Groundwater Flow and Transport Models with Algebraic Multigrid Preconditioning.

Iterative solvers preconditioned with algebraic multigrid have been devised as an optimal technology to speed up the response of large sparse linear systems. In this work, this technique was implemented in the framework of the dual delineation approach. This involves a single groundwater flow linear solution and a pure advective transport solution with different right-hand sides. The new solver was compared with other preconditioned iterative methods, the MODFLOW's GMG solver, and direct sparse solvers. Test problems include two- and three-dimensional benchmarks spanning homogeneous and highly heterogeneous and anisotropic formations. For the groundwater flow problems, using the algebraic multigrid preconditioning speeds up the numerical solution by one to two orders of magnitude. The algebraic multigrid preconditioner efficiency was preserved for the three dimensional heterogeneous and anisotropic problem unlike for the MODFLOW's GMG solver. Contrarily, a sparse direct solver was the most efficient for the pure advective transport processes such as the forward travel time simulations. Hence, the best sparse solver for the more general advection-dispersion transport equation is likely to be Péclet number dependent. When equipped with the best solvers, processing multimillion grid blocks by the dual delineation approach is a matter of seconds. This paves the way for its routine application to large geological models. The paper gives practical hints on the strategies and conditions under which algebraic multigrid preconditioning would remain competitive for the class of nonlinear and/or transient problems.

Unstructured Gridding for MODFLOW from Prior Groundwater Flow Models: A New Paradigm.

This work introduces a new unstructured gridding approach relying on feedback from a previous groundwater flow model. All cells in a relatively coarse model using a rectilinear grid are recursively subdivided following a cell wise specific discharge-based indicator to generate quadtree, octree or Voronoï grids. This technique leverages the full potential of the latest MODFLOW engines. The suitability of this approach is demonstrated on challenging single and multilayered heterogeneous formations. The proposed method is straightforward to implement in existing software packages. It supports iterative updating of groundwater flow models from the legacy rectilinear to unstructured grids.

Automatic Generation of Locally Refined Composite Grids for Efficient Solute Transport Modeling.

Widely used numerical models of solute transport processes in subsurface aquifers are limited to nonlocally refined rectangular, or logically rectangular, structured grids. This presents an unsuitable option to efficient numerical simulations maintaining an acceptable level of accuracy. Optimal selection of locally refined cells for efficient solute transport models is challenging to the current generation of numerical models. We present a novel and relatively simple to implement algorithm addressing these shortcomings. This method operates in four steps involving travel times simulations, a grid coarsening stage followed by a selective local grid refinement based on a cell-wise indicator, and a final postprocessing step. The refinement index is the sum of weighted logarithmic distributions of scaled forward and backward travel times. We calculate representative flow and transport properties at the two scales of the composite grid with a flow-based upscaling technique. We present two test problems to demonstrate the performances of this new gridding algorithm. We obtain the most important speedups for composite grids generated with the highest indicator thresholds. When hydrodynamic dispersion effects increase, we obtain less important speedups. An important outcome of this work is that grid design depends on nature and strength of the underlying flow and solute transport processes. Therefore, we suggest developing solute transport workflows integrating this grid generation algorithm as an integral component to build comprehensive and efficient groundwater models.

A Practical Grid-Based Alternative Method to Advective Particle Tracking.

Advective particle tracking is a conventional groundwater modeling technique that is widely used as a screening tool but lacks robustness as a reliable method for general applications. In this work, we investigate the suitability of industry-standard, finite-difference, grid-based methods as an alternative to the conventional particle-tracking approach. The presented method is classified as a particular case of the more general forward- or backward-in-time advective-dispersive probabilistic transport approaches. The proposed method is used as a powerful screening tool to accurately delineate and visualize capture zones around abstraction wells or outflow boundaries, the swept zones formed by injection wells or inflow boundaries, and the partitions associated with injection-pumping well doublets or inflowing-outflowing boundary pairs. Moreover, we show that the forward or backward travel times and residence time distributions are robustly simulated and visualized on the computational grid with little computational effort. Two examples are given to illustrate the key advantages of this method in groundwater applications. The first example considers a synthetic pump-and-treat remediation system in an irregularly layered aquifer. The second example involves four doublet wells operating for heat extraction in the Dogger geothermal reservoir in the Paris Basin, a leading European scale project. The presented approach is far more comprehensive as a screening tool than the conventional method, providing a natural intermediate step before processing the more general time-dependent advective-dispersive simulations.

Polymorphisms of the NOS3 gene in Tunisian patients with Behçet's disease.

Behçet's disease (BD) is a multisystem inflammatory disease characterized by recurrent orogenital ulceration, ocular inflammation and skin lesions. Reduced plasma nitric oxide (NO) levels in patients with BD have been implicated in the development of the endothelial abnormalities and thrombotic complications occurring in these patients. Polymorphisms in the endothelial nitric oxide synthase gene (NOS3) have been inconsistently associated with BD. This inconsistency may derive from population stratification secondary to ethnic diversity, and consideration limited to only one rather than combinations of polymorphisms. We studied three genetic variations in the NOS3 gene: a single nucleotide polymorphism in the promoter region -786T>C, in exon 7 (Glu298Asp), and a variable number of tandem repeats in intron 4 (4a4b) of the NOS3 gene in 100 unrelated Tunisian patients with BD and 148 healthy controls. In addition, we also examined the association of NOS3 gene haplotypes with BD. Analyses of the Glu298Asp, -786T>C and 4a4b polymorphisms were made by the polymerase chain reaction (PCR) restriction fragment length polymorphism technique and PCR genotyping, respectively. The distribution of the Glu298Asp genotype differed significantly between patients with BD and controls (P = 0.01). Allele Asp298 was significantly more frequent in patients with BD than in controls (P = 0.005, OR = 1.70, 95% CI 1.14-2.54). In contrast, distribution of alleles and genotypes of -786T>C and 4a4b polymorphisms was not different between the control and BD group. However, the frequency of Asp-T-4b haplotype was significantly higher in patients with BD than in healthy controls. By gender, the signification remained only for heterozygous men (P = 0.03) and homozygous women (P = 0.02). These results suggest that Glu298Asp polymorphism of the NOS3 gene is associated with BD susceptibility in Tunisian patients.

[Familial histoid leprosy]. / Lèpre histoïde familiale.

BACKGROUND: Histoid leprosy is a very particular and rare anatomoclinical form of lepromatous leprosy. Familial cases are extremely rare. We report two new cases of histoid leprosy in a sister and brother born of a non-consanguineous marriage. PATIENTS AND METHODS: We report the case of a sister and brother, aged 21 and 25 years respectively, who were admitted to the National Leprology Centre for multibacillary leprosy. Questioning revealed the existence of family contact with an uncle and two maternal cousins, all of whom had histoid leprosy. On clinical examination, multiple erythematous papules and nodules were noted, some of which were umbilicated while others were ulcerated. Palpation also revealed subcutaneous nodules on the thighs and forearms. No neurological disorders were found in the two patients. Histopathological analysis of cutaneous biopsy samples of nodular lesions for the two patients showed dermal-hypodermic nodular infiltrates comprising spindle cells with a few macrophages. Ziehl-Neelsen staining showed numerous alcohol-acid resistant bacilli (BAAR) without globi. Both patients were placed on the multi-drug regimen recommended by the WHO for multibacillary leprosy. An extremely favourable therapeutic response was obtained after 3 months of treatment. The patients had presented no relapse of erythema nodosum leprosum after two years of follow-up. CONCLUSION: Histoid leprosy is a clinical entity that must be clearly differentiated through its clinical and histopathological features, which distinguish it from polar lepromatous leprosy. There may be a genetic predisposition to this clinical leprosy form, but this requires confirmation by genetic studies.

[Malignant transformation of plantar ulcers in leprosy: experience of National Leprosy Center in Casablanca]. / Dégénérescence carcinomateuse des maux perforants plantaires d'origine lépreuse: expérience du Centre national de léprologie de Casablanca.

Malignant degeneration is a late complication of plantar ulcers in leprosy. The objective of this study is to describe and analyze the epidemiological, clinical, and therapeutic aspects of this complication in Morocco. A retrospective study was conducted from January 2000 to December 2009 at the National Center of Leprosy (CNL) in Casablanca. All our patients had a histological confirmation. Ten patients were included in this study. There were seven men and three women, with a mean age of 58.8 years. Six patients had a multibacillary form of leprosy and four had a paucibacillary form. The average duration of the plantar ulcers was 34.4 years. Clinical appearance at diagnosis was an ulcerative and vegetative tumor. Treatment was by radical amputation. Evolution was marked by metastatic spread in six patients. One patient died of disseminated disease. In Morocco, leprosy has been on the decline since 1990, but the occurrence of late complications in the leprosy patient as carcinoma of plantar ulcers persists. Prevention of these complications should be part of the national fight against leprosy.

[Histoid leprosy in Morocco: retrospective study of 18 cases]. / Lèpre histoïde au Maroc: etude rétrospective de 18 cas.

INTRODUCTION: Histoid leprosy is a special and rare anatomoclinical form of multibacillary leprosy. Most of the few large series describing this entity In literature have been reported from India. The purpose of this study was to analyze the epidemiological, clinical and therapeutic characteristics of patients with histoid leprosy in Morocco. MATERIAL AND METHODS: This retrospective study was conducted at the National Centre of Leprology (CNL) in Casablanca from January 1991 to December 2006. Only histologially confirmed cases of histoid leprosy were included. Epidemiological, clinical, histological and therapeutic characteristics were compiled from records and analyzed using EPI-Info version 6. RESULTS: Confirmed histoid leprosy accounted for 18 of the new cases of leprosy recorded at CNL recorded during the 16-year study period. There were 13 men and 5 women with a mean age of 35.2 years. Family exposure was noted in 9 patients (50%) including two who had more than two relatives with leprosy. Nodules/subcutaneous nodules were the most common morphological pattern (88.8%). Neurological involvement was found in 10 patients. Seven patients had grade 1 deformities. Slit skin smears from histoid lesions revealed abundant bacilli with a high bacteriological index ranging from 3 + to 5 + according to the Ridley index. All patients received antibiotic treatment according to the Moroccan protocol. Outcome was favorable in all patients. Six patients (33.3%) developed erythema nodosum leprosum during the course of disease. With a average follow-up of 9 years, no recurrence has been observed. DISCUSSION: Because of its multibacillary character and despite its rarity, histoid leprosy poses a challenge to the leprosy eradication in Morocco. Like other forms of multibacillary leprosy, histoid leprosy requires early detection and prompt multidrug therapy. These requirments should be made a priority in the national program against leprosy.

[The reversed homodigital island flap: 28 cases]. / Le lambeau en îlot homodigital à contre-courant : à propos de 28 cas.

AIMS: The purpose of the study is to evaluate the coverage of the distal tissue defect of long fingers using reversed homodigital island flap and comparison with other flaps. PATIENTS AND METHOD: It was a retrospective study of 28 cases of reversed homodigital island flap practiced in 28 patients to cover skin finger distal loss. The mean age was 29 years, the sex ratio was 0.17. The variety of à pédicule exclusivement vasculaire was the most used (89%). Partial necrosis of the flap was noticed only in two cases (7%). Six criteria were used to evaluate this coverage: the quality of the flap, the donor site, the neuroma formation, the cold intolerance, the mobility of the finger, and the satisfaction of the patient. A final score for every case was attributed. RESULTS: At the middle last follow-up, the results were good in 89% and average in 11%. CONCLUSION: The reversed homodigital island flap is a safe method offering multiple advantages and constitutes an interesting alternative in front of the distal tissue defect of the long finger.

[Pseudo-Kaposi's sarcoma secondary to superficial arteriovenous malformation: Stewart-Bluefarb syndrome]. / Pseudomaladie de Kaposi secondaire à une malformation artérioveineuse superficielle: syndrome de Stewart-Bluefarb.

BACKGROUND: Pseudo-Kaposi's sarcoma or Stewart-Bluefarb subtype acroangiodermatitis is uncommon and is caused by arteriovenous fistula and malformation. We report a new case. CASE REPORT: A 33-year-old man presented with painful red-violet plaque on the dorsum of the toes with angiomatous nodules on the sole. Histological and immunohistochemical studies for CD34 were consistent with Kaposi's sarcoma. Doppler ultrasonography and femoral angiography showed multiple distal arteriovenous shunts. Free-flow embolisation with fragments of Ethibloc gelatin sponge was performed and arteriography, performed immediately afterwards, showed delayed venous drainage. The outcome was good with complete drainage of the angiomatous lesions. DISCUSSION: Pseudo-Kaposi's sarcoma Stewart-Bluefarb subtype begins early in life in male subjects, with unilateral skin lesions. It bears clinical and histological resemblance to Kaposi's sarcoma. Doppler ultrasonography and angiography show arteriovenous fistulas that classically develop at shunts, explaining the role of traumatism and high vascular pressure in the genesis of this disease.

[Impact of polymetallic mine (Zn, Pb, Cu) residues on surface water, sediments and soils at the vicinity (Marrakech, Morocco)]. / Impact des residus d'une mine polymetallique (Zn, Pb, Cu) sur les eaux de surface, les sediments et les sols avoisinants (Marrakech, Maroc).

Metal sulphide tailings present a potential risk for the environment because of their natural oxidability which leads to the production of acid mine drainage. The prospected site close to Marrakech includes zinc, lead and copper sulphide deposits. This site is located in an agricultural area near the Tensift River which is used for irrigation. In addition to the tailing leachates, underground mine waters are also discharged into the river. This represents a potential risk for the environment and human health. The aim of this study was to assess the tailings impact on surface water, sediments and soil qualities. Chemical analysis of surface water and sediments collected downstream of the mine revealed that, water and sediments present high concentrations of major ions and heavy metals. The analysis also revealed spatial as well as temporal changes in the chemical properties of the studied water and sediments. These changes are attributed to the rising phenomena. The soil near the mine presents high content of sulphate. Its Zn, Pb, Cu and Fe contents are respectively 38, 15, 11 and 1.6 times higher than non contaminated soils located far away from the site. The soil irrigated with underground mine waters shows concentrations of SO4(2-), Cu, Zn, Fe, Cd and Pb which are respectively 4, 10, 28, 2, 9 and 12 times higher than soils which are not irrigated with this mine water. This study also showed that there has been a change in the physicochemical characteristics of water and sediments in the sampling points downstream of the mine before its closure and after its activity renewal.

[Impact of mining wastes on the physicochemical and biological characteristics of groundwater in a mining area in Marrakech (Morocco)]. / Impact des rejets miniers sur la qualite physico-chimique et biologique des eaux souterraines d'une zone miniere dans la region de Marrakech (Maroc).

Metal sulphide tailings represent a potential risk basically for the environment and particularly for water resources, because of their natural oxidisability which leads to the production of acid/neutral mine drainage. The prospected site close to Marrakech includes zinc, lead and copper sulphide deposits. This site is located in an agricultural area where ground water is used both for irrigation and drinking. Eco-toxicological investigations have been undertaken in order to asses the tailings impact on water quality in nearby wells. These investigations include physico-chemical characterization of the groundwaters as well as faunistic population determination. As compared to standard wells, waters from the wells located downstream of the mining site, have high electrical conductivities and high major ions contents, which can reach: 755 mg l(-1) in SO4(2-), 1670 mg l(-1) in Ca2+, 528 mg l(-1) in Mg2+, 2289 mg I(-1) in Na+ and 14981 mg l(-1) in Cl-. The fauna distribution analysis carried out around the studied wells shows qualitative and quantitative differences according to the flow gradient of the groundwaters. Areas located upstream of the mine tailings site are richer in stygobite species (Type and quantity) than those located downstream or close to it. It is likely that these biological differences are due to water quality alteration induced by the mining activity.

[Congenital cutaneous candidiasis: a case report and review]. / La candidose cutanée congenitale: a propos d'une observation et revue de la littérature.

The aim of this article is to report a case of congenital cutaneous candidiasis (CCC). We describe the clinical features and emphasize the role of laboratory testings to assess diagnosis in the newborn and to prevent this condition by screening vaginal candidiasis in pregnant women. A full-term, 3500-g male was born by spontaneous vaginal delivery to a 30-year-old healthy woman. On physical examination, he was a well-developed, vigorous newborn. Since the first hours of his life he presented erythematous maculae diffusely distributed on the skin and pustules overlying areas of confluent macular erythema on his trunk and extremities. The palms and soles were not affected. Neither oral thrush nor peri-anal lesions have been observed. The rest of the physical examination was normal. Microscopic examination of skin scrapings showed the presence of many yeasts and the culture permitted the identification of a strain of Candida albicans. Precocity and extent of the cutaneous signs attest a congenital cutaneous candidiasis and eliminate the other skin diseases of similar clinical symptoms. Topical antifungal therapy (econazole) was given and the cutaneous lesions disappeared after 20 days. CCC appears to be acquired in utero by the ascension of organisms from an infected vagina into the uterine cavity. This condition is preventable with systematic screening and treatment of vulvo-vaginitis due to Candida albicans in pregnant women, The important role played by the laboratory of mycology remains essential.

[Porphyria cutanea tarda in a hemodialysed patient with hepatitis C virus infection: efficacy treatment by small repeated phlebotomies]. / Porphyrie cutanée tardive chez un hémodialysé ayant une hépatite virale C: efficacité du traitement par petites phlébotomies.

INTRODUCTION: Porphyria cutanea tarda (PCT) is a disorder of heme biosynthesis resulting from deficiency in the enzyme uroporphyrinogen decarboxylase. In the sporadic form of PCT, there are many agents that trigger the clinical manifestations. EXEGESIS: We report a case of PCT in an hemodialysed patient with hepatitis C virus infection (HVC). He was treated with small repeated phlebotomies of 50 ml every week with photoprotection, eviction of traumatismes and inducing drugs. A clinical remission was induced after five months of treatment. CONCLUSION: A proper diagnosis of PCT in non uremic hemodialysed patients requires fractionation of serum and fecal porphyrin changes. Management of this patients is difficult. Small repeated phlebotomies (50-100 ml) could be an interesting therapy.

[Histoid leprosy with erythema nodosum leprosum]. / Lèpre histoïde avec érythème noueux lépreux.

Histoid leprosy is a particular variant of lepromatous leprosy presenting as cutaneous or subcutaneous nodular and/or plaque-like lesions arising form apparently normal skin. It is characterized histologically by spindle-shaped histiocytes in interlacing bundles and whorls, containing numerous intact and rod-shaped Mycobacterium leprae. It can occur de novo or secondary in patients treated for a long course by dapsone alone. We describe a case of lepromatous leprosy treated according to the national Moroccan protocol who developed histoid lesions during his treatment by dapsone. The patient responded well to fluoroquinolone, rifampicin and clofazimine, with however, the occurrence of erythema nodosum leprosum.

[Cutaneous filariasis Loa Loa: 26 moroccan cases of importation]. / Filariose cutanée à Loa Loa. 26 cas marocains d'importation.

INTRODUCTION: Loa Loa filariasis or loiasis is a subcutaneous and bloody vectorial parasitosis. It is endemic in forest and swamp areas of west and central Africa. PATIENTS AND METHODS: We reviewed 26 moroccan cases of importation. All patients had visited Equatorial Guinea. Transient and migratory edema with pruritus were described in all cases and seen in 5 cases. A history of eyeworm was reported in 13 patients and subcutaneous migration of adult Loa Loa in 19 patients. Other features including fever and asthenia were reported in 11 patients. Microfilaremia was positive in 8 patients and eosinophilia was present in 22 patients. Fifteen patients were treated with diethylcarbamazine alone and 9 patients with ivermectin and diethylcarbamazine. Two patients were treated with ivermectin alone. Relapses were noted in 8 cases. No visceral complications were noted excepting one case of terminal hematury. DISCUSSION: Loiasis is a filarial infection of man that occurs exclusively in central and West Africa. The most common symptoms being pruritus with temporary, localised edema, subcutaneous and subconjonctival eye passage of the adult worm, fever and fatigue. The biologic diagnosis of loaisis is made on peripheral microfilariae, filarial serology and eosinophil count. Travel and visits endemic areas were at the origin of the emergence of this pathology in Morocco. Filarial Loa Loa infection should be treated with diethylcarbamazine and/or ivermectin.

The chaperonin GroEL and other heat-shock proteins, besides DnaK, participate in ribosome biogenesis in Escherichia coli.

It has been shown that in Escherichia coli the chaperone DnaK is necessary for the late stages of 50S and 30S ribosomal subunit assembly in vivo. Here we focus on the roles of other HSPs (heat-shock proteins), including the chaperonin GroEL, in addition to DnaK, in ribosome biogenesis at high temperature. GroEL is shown to be required for the very late 45S-->50S step in the biogenesis of the large ribosome subunit, but not for 30S assembly. Interestingly, overproduction of GroES/GroEL can partially compensate for a lack of DnaK/DnaJ at 44 degrees C.

DnaK-dependent ribosome biogenesis in Escherichia coli: competition for dominance between the alleles dnaK756 and dnaK+.

The Escherichia coli chaperone DnaK is vital for many cellular functions, including ribosome biogenesis at high temperature. Thus, the dnaK756-ts (lambdaR) mutant, at the non-permissive temperature, is inhibited at a late stage of ribosome assembly, yielding 21S, 32S and 45S precursor particles. This defect, unlike the lambda resistance and thermosensitivity phenotypes, is not complemented by lysogenisation with a transducing phage lambda dnaK+ bearing the wild-type dnaK gene. However this dominant phenotype becomes recessive when dnaK+ is expressed from a medium-copy-number plasmid. On the other hand, an excess of DnaK causes an unexpected dominant-lethal effect of the dnaK756 allele near non-permissive temperatures. This interplay between the dnaK+ and dnaK756 alleles supports the idea of that DnaK oligomers form in the cell.