Guest displacement in silicon clathrates

We study both theoretically and experimentally the structure of the doped silicon clathrate II NaxSi34. We find that contrary to published works, the sodium atoms do not retain the T-d symmetry inside the Si-28 cages and move about 1 A away from the center of the cage. This displacement, in conjunction with that of a sodium atom in an adjacent Si-28 cage, leads to a "dimerization" of sodium atoms. As a consequence, Rietveld refinements of x-ray diffraction spectra and transport, vibrational, and electronic properties must be revisited

Fresnel diffraction in an interferometer: application to MATISSE

While doing optical study in an instrument similar to the interferometers dedicated to the Very Large Telescope (VLT), we have to take care of the pupil and focus conjugations. Modules with artificial sources are designed to simulate the stellar beams, in terms of collimation and pupil location. They constitute alignment and calibration tools. In this paper, we present such a module in which the pupil mask is not located in a collimated beam thus introducing Fresnel diffraction. We study the instrumental contrast taking into account the spatial coherence of the source, and the pupil diffraction. The considered example is MATISSE, but this study can apply to any other instrument concerned with Fresnel diffraction.Comment: 8 pages- to appear in Proceedings of SPIE Astronomical Telescopes and Instrumentation 201

What is the Profitability of a Photovoltaic Installation in France for an Individual?

The energy transition will require the use of renewable energy resources that will allow us to reach our decarbonization objectives. In addition to states and institutions, individuals have an important role to play in this transition, particularly with the installation of photovoltaic panels. But for individuals to use this source of energy, they must be guaranteed a financial return that encourages them to take the plunge. Several companies, in a commercial approach, guarantee returns on investment after 2–3 years for any installation. But is the financial profitability always guaranteed? In France, several types of photovoltaic installations are possible, total resale and self-consumption. For each one, the profitability will vary and depends on many parameters such as the initial and daily investment, the irradiation, the electricity buy-back price, and the consumption. This paper explains the calculation methodology for both typologies and shows that currently, in most cases, a self-consumption installation is more profitable than a full resale installation but is far from obtaining the returns on investment predicted by the commercials. If self-consumption is more profitable today, this is due to the fact that the investment (initial or annual) is less important, and that the price of electricity becomes more and more expensive while at the same time the price of resale decreases from year to year

Parasitic Interference in Long Baseline Optical Interferometry: Requirements for Hot Jupiter-like Planet Detection

International audienceThe observable quantities in optical interferometry, which are the modulus and the phase of the complex visibility, may be corrupted by parasitic fringes superimposed on the genuine fringe pattern. These fringes are due to an interference phenomenon occurring from stray light effects inside an interferometric instrument. We developed an analytical approach to better understand this phenomenon when stray light causes cross talk between beams. We deduced that the parasitic interference significantly affects the interferometric phase and thus the associated observables including the differential phase and the closure phase. The amount of parasitic flux coupled to the piston between beams appears to be very influential in this degradation. For instance, considering a point-like source and a piston ranging from λ/500 to λ/5 in the L band (λ = 3.5 μm), a parasitic flux of about 1% of the total flux produces a parasitic phase reaching at most one-third of the intrinsic phase. The piston, which can have different origins (instrumental stability, atmospheric perturbations, etc.), thus amplifies the effect of parasitic interference. According to the specifications of piston correction in space or at ground level (respectively λ/500 ≈ 2 nm and λ/30 ≈ 100 nm), the detection of hot Jupiter-like planets, one of the most challenging aims for current ground-based interferometers, limits parasitic radiation to about 5% of the incident intensity. This was evaluated by considering different types of hot Jupiter synthetic spectra. Otherwise, if no fringe tracking is used, the detection of a typical hot Jupiter-like system with a solar-like star would admit a maximum level of parasitic intensity of 0.01% for piston errors equal to λ/15. If the fringe tracking specifications are not precisely observed, it thus appears that the allowed level of parasitic intensity dramatically decreases and may prevent the detection. In parallel, the calibration of the parasitic phase by a reference star, at this accuracy level, seems very difficult. Moreover, since parasitic phase is an object-dependent quantity, the use of a hypothetical phase abacus, directly giving the parasitic phase from a given parasitic flux level, is also impossible. Some instrumental solutions, implemented at the instrument design stage for limiting or preventing this parasitic interference, appear to be crucial and are presented in this paper

Mycophenolic Acid overcomes imatinib and nilotinib resistance of chronic myeloid leukemia cells by apoptosis or a senescent-like cell cycle arrest.

International audienceWe used K562 cells sensitive or generated resistant to imatinib or nilotinib to investigate their response to mycophenolic acid (MPA). MPA induced DNA damage leading to cell death with a minor contribution of apoptosis, as revealed by annexin V labeling (up to 25%). In contrast, cell cycle arrest and positive staining for senescence-associated β-galactosidase activity were detected for a large cell population (80%). MPA-induced cell death was potentialized by the inhibition of autophagy and this is associated to the upregulation of apoptosis. In contrast, senescence was neither decreased nor abrogated in autophagy deficient K562 cells. Primary CD34 cells from CML patients sensitive or resistant to imatinib or nilotinib respond to MPA although apoptosis is mainly detected. These results show that MPA is an interesting tool to overcome resistance in vitro and in vivo mainly in the evolved phase of the disease

Is There a Relationship between Ovarian Epithelial Dysplasia and Infertility?

Aim. Ovarian epithelial dysplasia was initially described in material from prophylactic oophorectomies performed in patients at genetic risk of ovarian cancer. Similar histopathological abnormalities have been revealed after ovulation stimulation. Since infertility is also a risk factor for ovarian neoplasia, the aim of this study was to study the relationship between infertility and ovarian dysplasia. Methods. We blindly reviewed 127 histopathological slides of adnexectomies or ovarian cystectomies according to three groups—an exposed group to ovulation induction (n = 30), an infertile group without stimulation (n = 35), and a spontaneously fertile control group (n = 62)—in order to design an eleven histopathological criteria scoring system. Results. The ovarian dysplasia score was significantly higher in exposed group whereas dysplasia score was low in infertile and control groups (resp., 8.21 in exposed group, 3.69 for infertile patients, and 3.62 for the controls). In the subgroup with refractory infertility there was a trend towards a more severe dysplasia score (8.53 in ovulation induction group and 5.1 in infertile group). Conclusion. These results raise questions as to the responsibility of drugs used to induce ovulation and/or infertility itself in the genesis of ovarian epithelial dysplasia

Importance of Massularia accuminata (Myrtaceae), Piptadiniastrum africanum (Fabaceae), and Costus afer (Zingiberaceae), Three Plants of the Cameroonian Traditional Medicine Used in the Treatment of Sinusitis by the Village Populations of Bomb-Lissomb and

Costus afer, Massularia acuminate and Piptadeniastrum africanum are three plants used in Cameroonian traditional medicine to treat sinusitis. The aim of this study is to justify the interest granted to this three species in the treatment of this disease and to promote their sustainable management. The study was carried out at Bomb-Lissomb and at the goat market. Several types of data were collected: data on the use of these plants in traditional anti-sinus medicine, data on their varied other uses by local residents, data on the availability of these plants as well as data on the interest that these species could generate. Furthermore, the evolution of treatment in patients who received plant extracts was followed after two months to justify their efficiency against sinusitis. The technique used for the removal of organs from the plant's vegetative growth was described. Finally, phytochemical screening of extracts obtained after aqueous maceration of plant organs was performed.  Amongst the informants who took part to this study, 17 mentioned barks of Piptadeniastrum africanum and 29 mentioned fruits of Massularia acuminata to treat sinusitis. Treatments administered to patients are made either from monospecific recipes or from a mixture of two or three plants. The average duration of treatment is 29 days when patients are only treated with fruits of Massularia acuminata and 12 days when they are subjected to treatments based on a recipe made from stem barks of Piptadeniastrum africanum and fruits of Massularia acuminate. Treatment seems to be effective from the 2nd time the medication is taken. Harvesting techniques allowing large quantities of organs to be removed from a few individuals affects the regeneration of these individuals. Stems barks and leaves of Massularia acuminata contain almost the same bioactive compounds as fruits

Studying complex interventions : reflections from the FEMHealth project on evaluating fee exemption policies in West Africa and Morocco

Peer reviewedPublisher PD

Tissue-Specific Biomarker Responses in the Blue Mussel Mytilus spp. Exposed to a Mixture of Microplastics at Environmentally Relevant Concentrations

The impact of a microplastic (MP) mixture composed of polyethylene (PE) and polypropylene (PP) plastic particles, prepared from commercially available products, was evaluated in blue mussels Mytilus spp. exposed to three environmentally relevant concentrations: 0.008 μg L−1 (low), 10 μg L−1 (medium), and 100 μg L−1 (high). Organisms were exposed for 10 days followed by 10 days of depuration in clean seawater under controlled laboratory conditions. The evaluation of MP effects on mussel clearance rate, tissue structure, antioxidant defenses, immune and digestive parameters, and DNA integrity were investigated while the identification of plastic particles in mussel tissues (gills, digestive gland, and remaining tissues), and biodeposits (feces and pseudofaeces) was performed using infrared microscopy (μFT-IR). Results showed the presence of MPs only in the digestive gland of mussels exposed to the highest tested concentration of MPs with a mean of 0.75 particle/mussel (after the 10 days of exposure). In biodeposits, PE and PP particles were detected following exposure to all tested concentrations confirming the ingestion of MPs by the organisms. A differential response of antioxidant enzyme activities between digestive gland and gills was observed. Significant increases in superoxide dismutase (SOD) and catalase (CAT) activities were measured in the digestive gland of mussels exposed to the low (0.008 μg L−1) and medium (10 μg L−1) concentrations of MPs and in the gills from mussels exposed to the highest concentration (100 μg L−1) of MPs that could be indicative of a change in the redox balance. Moreover, an increase in acid phosphatase activity was measured in hemolymph of mussels exposed to 0.008 and 10 μg L−1 concentrations. No significant difference was observed in the clearance rate, and histopathological parameters between control and exposed mussels. This study brings new insights on the potential sublethal impacts of MPs at environmentally relevant concentrations in marine bivalves