Scaling behavior of electron decoherence in a graphene Mach-Zehnder interferometer.

Over the past 20 years, many efforts have been made to understand and control decoherence in 2D electron systems. In particular, several types of electronic interferometers have been considered in GaAs heterostructures, in order to protect the interfering electrons from decoherence. Nevertheless, it is now understood that several intrinsic decoherence sources fundamentally limit more advanced quantum manipulations. Here, we show that graphene offers a unique possibility to reach a regime where the decoherence is frozen and to study unexplored regimes of electron interferometry. We probe the decoherence of electron channels in a graphene quantum Hall PN junction, forming a Mach-Zehnder interferometer1,2, and unveil a scaling behavior of decay of the interference visibility with the temperature scaled by the interferometer length. It exhibits a remarkable crossover from an exponential decay at higher temperature to an algebraic decay at lower temperature where almost no decoherence occurs, a regime previously unobserved in GaAs interferometers.

Quantum Hall Valley Splitters and a Tunable Mach-Zehnder Interferometer in Graphene.

Graphene is a very promising test bed for the field of electron quantum optics. However, a fully tunable and coherent electronic beam splitter is still missing. We report the demonstration of electronic beam splitters in graphene that couple quantum Hall edge channels having opposite valley polarizations. The electronic transmission of our beam splitters can be tuned from zero to near unity. By independently setting the beam splitters at the two corners of a graphene p-n junction to intermediate transmissions, we realize a fully tunable electronic Mach-Zehnder interferometer. This tunability allows us to unambiguously identify the quantum interferences due to the Mach-Zehnder interferometer, and to study their dependence with the beam-splitter transmission and the interferometer bias voltage. The comparison with conventional semiconductor interferometers points toward universal processes driving the quantum decoherence in those two different 2D systems, with graphene being much more robust to their effect.

[Changes in malaria prevalence and management of fevers from 2000 to 2012 in Casamance, Senegal]. / Évolution de la prévalence du paludisme et de la prise en charge des fièvres de 2000 et 2012 en Casamance, Sénégal.

Before 2006 in Senegal, in the absence of clinical diagnosis, all fever cases were considered as malaria and treated with chloroquine. Between 2004-2006, to face the dramatic increase of Plasmodium falciparum resistance to chloroquine, the combination of amodiaquine plus sulfadoxine-pyriméthamine was recommended for treatment. In 2006, rapid diagnostic tests were introduced and the treatment with a combination of artesunate plus amodiaquine (ASAQ) became the national recommendation for malaria treatment in 2007. This coincided with a decrease of the prevalence of malaria cases and change in fever management. Since 1995 in Mlomp in Casamance, thin and thick blood smear examination has systematically been done in patients with fever and clinical signs of malaria, and treatment with ASAQ given as experimental procedure. Between 2000 and 2012, 70,892 outpatients were attending the health center, and 51.2% of them for fever. Among these fever cases, 72.4% were suspected of malaria and 27.6% were identified as bacterial and viral infections. Confirmed malaria cases decreased dramatically from 1365 in 2000 to 53 in 2012. While comparing the 2 periods 2000-2006 and 2007-2012, the number of fever cases decreased by half, the number of fever identified as non malaria doubled and malaria treatment given decreased by 86%. Improvement of fever management in Mlomp has contributed to a better identification of their cause and to a decrease of inappropriate malaria treatments.

[Gametocyte carriage in asymptomatic Plasmodium falciparum infections in Haiti (2010-2013)]. / Portage de gamétocytes de Plasmodium falciparum en Haïti en 2010-2013.

A survey conducted from May 2010 to October 2013 in five from ten departments of Haiti among 5,342 persons aged from 1 to 107 years showed a gametocytic rate = 3.2%. However, it varies greatly from one Department to another, ranging from 0.5% in Grande Anse Department to 5.9% in Southeast Department. Malaria is present in Haiti in heterogeneous coastal foci. Gametocytes occur at all ages, but two times most often in male under 20 years. Entomological studies in Haiti are needed to better characterize the relationships between man and the vector Anopheles albimanus, adapting the fight more effectively.

[Epidemiological characteristics of malaria in the village of Corail, Grand'Anse, Haiti]. / Caractéristiques épidémiologiques du paludisme dans la commune de Corail, Grande Anse, Haïti.

Malaria is considered to be a major problem of public health in Haiti. However the impact of Plasmodium falciparum on health is poorly known in this country. The objective of this study is to verify the incidence of malaria as the cause of hospital consultation and to evaluate the rate of P. falciparum gametocytes carriage among the population living in a municipality within the Department of Grand'Anse where the prevalence of malaria is considered one of the strongest in Haiti. Analysis of hospital statistics of Corail (Grand'Anse) showed that only 17.4% of consultations of patients presenting with fever are due to microscopically confirmed malaria. The fraction of the population most affected is that of adults aged 15-39 years (55% of cases). Children under five represent only 11% of the cases. A community survey showed the rarity of the carriage of gametocytes in asymptomatic persons (0.9%). In Haiti, the epidemiological characteristics of malaria must have specified and documented field studies in order to adapt a strategy for fighting against this parasitic disease with greater efficiency.

Rapid multi-residue and multi-class qualitative screening for veterinary drugs in foods of animal origin by UHPLC-MS/MS.

Multi-class UHPLC-MS/MS was developed for the analysis of more than 160 regulated or banned compounds of various classes: anthelmintics including benzimidazoles, avermectins and others; antibiotics including amphenicols, beta-lactams, macrolides, pyrimidines, quinolones, sulphonamides and tetracyclines; beta-agonists; corticosteroids; ionophores; nitroimidazoles; non-steroidal anti-inflammatory agents; steroids; and tranquillisers. Samples were extracted with acetonitrile, without any additional purification step, and analysed by using UHPLC-MS/MS. Validation was done in accordance with the guidelines laid down by European Commission Decision 2002/657/EC for qualitative screening methods. This simple method proved applicable to routine screening for residues in egg, honey, milk and muscle samples at half the maximum concentration permitted by the European Union for each drug. In most cases, the target value was set at 5 µg kg(-1) for unauthorised compounds.

Dosing accuracy of artesunate and amodiaquine as treatment for falciparum malaria in Casamance, Senegal.

OBJECTIVES: Several products of artesunate plus amodiaquine (AS + AQ) are being deployed in malaria-endemic countries for treating uncomplicated falciparum malaria but dosing accuracy and consequential effects on efficacy and tolerability have not been examined. METHODS: Patients with parasitologically confirmed, uncomplicated falciparum malaria were treated and followed by research teams or local health centre staff in Casamance, Senegal. AS + AQ was given as: (i) loose combination (AS 50 mg, AQ 200 mg), dosed on body weight, or (ii) co-blistered product (AS 50 mg, AQ 153 mg) dosed by weight or age. Target doses were: (i) AS 4 (2-10) mg/kg/day and (ii) AQ 10 (7.5-15) mg/kg/day. Patients receiving therapeutic doses defined dosing accuracy. Treatment-emergent signs and symptoms (TESS) were recorded. RESULTS: A total of 3277 patients were treated with loose (n = 1972, weight-dosed) or co-blistered (n = 1305, 962 age-dosed, 343 weight-dosed) AS + AQ by the research team (n = 966) or clinic staff (n = 2311). AS was dosed correctly in >99% with all regimens. Loose AQ by weight was 98% correct. The co-blister AQ overdosed 18% of patients when dosed by age and underdosed 13% by weight. Low weight was an independent risk factor for overdosing. The co-blister had significantly more TESS than the loose product [117/1305 (9%) vs. 41/1972 (2%), relative risk = 4.3 (95% CI: 3.0-6.1, P < 0.0001)]. Age-based dosing accounted for the difference. TESS occurred mostly within one day (72%) and were mild or moderate (75%). CONCLUSION: Artesunate is easier to dose than AQ. Currently available age-dosed, co-blistered AS + AQ tends to overdose AQ and is less well tolerated than loose tablets. It is not the optimal presentation of AS + AQ.

Systematic review of utilities in abdominal aortic aneurysm.

INTRODUCTION: Two main treatments exist for the repair of abdominal aortic aneurysm (AAA). Open surgical repair has been the standard treatment, but more recently endovascular aneurysm repair (EVAR) has been introduced as a less invasive technique. To compare the long-term outcomes of these, utility outcomes have been suggested to be relevant. OBJECTIVE: To review studies comparing the utility outcomes of open repair and EVAR treatment for AAA. DESIGN: database search with strict inclusion and exclusion criteria. MATERIALS AND METHODS: The search was performed in PubMed and EMBASE covering terms relating to AAA and utility. Studies were analysed qualitatively. RESULTS: 10 studies of AAA met the review criteria. The comparative utility scores for the different treatments varied considerably between studies. A Canadian cohort study estimated EVAR as more favorable than open repair, while randomised controlled trials reported lower utilities with EVAR, except for one month post-surgery in the EVAR 1 trial. Furthermore, after screening for AAA, patients testing positive gave similar QoL-5D scores, but worse visual analogue scores than those testing negative. CONCLUSION: There were few studies calculating utilities in AAA, with inconsistent findings. The limited reporting of data prevents in-depth analysis to explain the differences.

[Tolerance of amodiaquine]. / Tolérance de l'amodiaquine.

Amodiaquin is still considered as a poorly tolerated antimalarial causing hematological and hepatic toxicity. In view of complications observed during prophylaxis, the WHO has advised against the use of amodiaquin for prophylaxis as well as treatment. However due to the rapid increase in chloroquine resistance and to the absence of reported cases of toxicity during treatment, the WHO has reconsidered its position and now accepts therapeutic use of amodiaquin under some conditions. It has been demonstrated that amodiaquin activates release of quinoneimine granulocytes causing hematological toxicity. In liver microsomes, metabolism into desethyl derivatives is catalyzed by cytochrome P450 CYP2C8 that has several variant forms with low activity on amodiaquin clearance. Carriers of these variants are at a higher risk for adverse effects. Currently the safety and effectiveness of amodiaquin in association with artesunate has been documented and this therapeutic combination is now recommended for first line treatment of uncomplicated Plasmodium falciparum malaria in 18 African countries.

Poisoning by Cnestis ferruginea in Casamance (Senegal): an etiological approach.

Since several years, in the area of Kabrousse in Casamance (Senegal), a neurotoxic syndrome has caused more than 50 human deaths. Field studies showed that epidemic could be due to consumption of leave decoction of Cnestis ferruginea, a tropical plant belonging to the Connaraceae family. An ethnobotanical study has been conducted in order to investigate the traditional uses of C. ferruginea, and describe the circumstances and the symptoms of this plant poisoning. As a first experimental approach, the leave decoction was tested for its ability to induce cytotoxic effects using the XTT method. A phytochemical approach revealed the presence of methionine sulfoximine (MSX), a neurotoxic amino acid, in the plant extract by gas chromatography-mass spectrometry (GC-MS). The description of this poisoning, the cytotoxic activity of the decoction and the occurence of MSX in leaves of C. ferruginea constituted the first etiological data on this poisoning.

[Treatment of pediatric malaria in Africa: act at issue]. / Traitement du paludisme de l'enfant en Afrique: les act en question.

Artemisinin-based combination therapies (ACT) have been proposed as alternatives to currently used antimalarials and are poised large-scale deployment in Africa. These combinations are particularly attractive for managing malaria in children. Expected benefits of ACT include enhanced efficacy, rapid action, stabilized antimalarial resistance growth and lower malaria transmission. This article discusses what can be reasonably expected of ACT in an African setting with emphasis on patient comfort.

[Malignant peripheral nerve sheath tumor in the posterior mediastinum]. / Tumeur maligne de la gaine d'un nerf périphérique: une lésion rare du médiastin postérieur.

We report the case of a 52-year-old male patient who developed a malignant peripheral nerve sheath tumor (MPNST) localized in the posterior mediastinum. The diagnosis of this rare tumor is difficult because the clinical presentation of the benign or malignant types is often similar, i.e. elective pain and bone erosions. Similarly, radiological procedures do not always allow distinction between the two types. MNR and CT-scan are the first line procedures: they localize and characterize the lesions, and CT-scan can also be a guide for biopsies. Histological diagnosis is required, but diagnosis can be compromised by the heterogeneous nature of the tumor. Surgical treatment should be undertaken whenever possible. Survival was unusually long in our patient, more than 5 years after discovery of the MPNST. This type of sarcoma is often very aggressive with frequent development of local recurrences and metastases.

Plasmodium falciparum in vitro susceptibility to antimalarial drugs in Casamance (southwestern Senegal) during the first 5 years of routine use of artesunate-amodiaquine.

We have monitored the in vitro sensitivities of Plasmodium falciparum isolates predeployment and during the deployment of artesunate plus amodiaquine treatment in Mlomp, Casamance (southwestern Senegal) during 2000 to 2004. Parasites remained susceptible to both drugs. Chloroquine resistance levels were high but stable. Quinine continues to be effective.

The silent sinus syndrome.

Silent sinus syndrome is a rare clinical entity typically characterized by spontaneous and progressive enophthalmos and hypoglobus caused by an alteration of the normal orbital architecture and function from maxillary collapse in the setting of the chronic maxillary sinus hypoventilation. The authors report an unusual case revealed by mild dental pain, present the imaging (before, during and after the development of the disease), discuss the different theories related to pathogenesis and comment the treatment.

Traitement du paludisme de l'enfant en Afrique : les ACT en question

Les Artemisinin-based Combination Therapies (ACT) representent la majorite des alternatives aux antipaludiques de reference et sont sur le point d'etre deployees largement en Afrique. Elles sont particulierement attractives pour traiter les enfants. Les vertus annoncees de ces associations sont multiples : puissance accrue; rapidite d'action; stabilisation de la chimioresistance et reduction de la transmission. L'abondante litterature consacree aux ACT depuis quelques annees permet de faire le point sur ces divers aspects; en insistant sur la question du confort des enfants malades

Economic evaluation of a policy change from single-agent treatment for suspected malaria to artesunate-amodiaquine for microscopically confirmed uncomplicated falciparum malaria in the Oussouye District of south-western Senegal.

Senegal is changing policy for case management of uncomplicated falciparum malaria, which hitherto is diagnosed clinically and treated with chloroquine or intramuscular quinine. The WHO recommends artemisinin-based combinations for treating falciparum malaria, preferably based on a parasitological diagnosis. There are no economic projections if such a policy were introduced in Senegal. We have conducted a preliminary economic assessment of such a policy change. The study took place in the chloroquine-resistant district of Oussouye in south-western Senegal. We reviewed clinic registers of the district health posts (n=5) from 1996 to 2001, and piloted artesunate combined with amodiaquine (at 4 and 10 mg/kg/day x 3 days respectively) (AS--AQ) for treating slide-proven falciparum malaria during two rainy seasons (2000 and 2001) at one health centre. These data were used to calculate current direct patient costs (clinic visit, diagnosis, drugs) of malaria treatment and project future costs for the district. The robustness of the model was tested by allowing for different drug failure rates and costs of diagnosis. During 1996--2001, the mean number of primary treatments per year was 7654 for a mean, direct cost of 17,452 US dollars to the community. Clinical diagnosis resulted in over-treatment: 56% and 66% in the wet and dry seasons respectively. Current policy leads to substantial drug wastage and excess direct costs for the community. The direct costs of implementing AS-AQ for slide-proven malaria would be 8,150 US dollars (53% less expensive). Studies examining the public health effect and economics of deploying AS--AQ on a wider scale are underway in Senegal.