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denote the largest product of distinct primes whose sum does not exceed
. The main result of this paper is that the property for all
, we have
denotes the inverse function of the logarithmic integral) is equivalent to the Riemann hypothesis.
We report the discovery of the first young brown dwarf in the Serpens cloud (BD-Ser 1). It is obscured by more than ten magnitudes of visual absorption as indicated by near infrared (NIR) photometric survey at the NTT and confirmed by NIR spectroscopy at the VLT. We estimate the mass of this brown dwarf to be M ~ 0.05 M⊙ and its age to be ~ 3.5 Myr. Available NIR indices in the literature (designed for field brown dwarfs) fail to provide its current spectral type but using a model they correctly determine its future spectral type to be T. This is the first young brown dwarf ever found deeply embedded in the Serpens star formation region
This is the first record of the black scorpionfish Scorpaena porcus being found in the eastern English Channel. A specimen was caught on 15 October 2012 off the port of Courseulles-sur-mer. It measured 31.6 cm and weighted 800 g. From a study of its sagittal otolith, this specimen appeared to be 9 years old.
The aim of this project was to evaluate the impact of probiotic (Phaeobacter gallaeciensis, X34 strain) treatment on the complete development (from veliger to metamorphosis) of Pecten maximus larvae in the context of a bacterial challenge and in conditions more representative of hatchery practices. To that effect, the present study was divided into two main steps. In the first, we used in vitro analyses (antibiograms and microplate assays) to validate the inhibition abilities of X34 on the growth of four Vibrio pathogen species. During the second step, we added pathogens (Vibrio pectenicida) into rearing tanks after two weeks of pre-treatment with the probiotic and then followed the larval development of Pecten maximus through the monitoring of survival rates, shell lengths and metamorphosis ability. Moreover, antioxidant (catalase and superoxide dismutase) and lipids peroxidation activities were also measured after bacterial challenge in order to evaluate the physiological response of larvae to pathogen exposition. Our results indicated an activation of the two selected antioxidant enzymes after bacterial challenge, but the increase was significantly lower in probiotic treated larvae. At the end of the experiment, the strain X34 treatment prevented a mass mortality event and showed a significant increase in the number of individuals reaching competence, when compared to untreated larvae.
Gestational methyl donor deficiency (MDD) leads to growth retardation as well as to cognitive and motor disorders in 21-d-old rat pups. These disorders are related to impaired neurogenesis in the cerebral neurogenic areas. Olfactory bulbs (OB), the main target of neuronal progenitors originating from the subventricular zone, play a critical role during the postnatal period by allowing the pups to identify maternal odour. We hypothesised that growth retardation could result from impaired suckling due to impaired olfactory discrimination through imbalanced apoptosis/neurogenesis in the OB. Since neurosteroidogenesis modulates neurogenesis in OB, in the present study, we investigated whether altered neurosteroidogenesis could explain some these effects. Pups born to dams fed a normal diet (n 24) and a MDD diet (n 27) were subjected to olfactory tests during the lactation and weaning periods (n 24 and 20, respectively). We studied the markers of apoptosis/neurogenesis and the expression levels of the key neurosteroidogenic enzyme aromatase, the cholesterol-transfer protein StAR (steroidogenic acute regulatory protein) and the ERα oestrogen receptor and the content of oestradiol in OB. The 21-d-old MDD female pups displayed lower body weight and impaired olfactory discrimination when compared with the control pups. MDD led to greater homocysteine accumulation and more pronounced apoptosis, along with impaired cell proliferation in the OB of female pups. The expression levels of aromatase, StAR and ERα as well as the content of oestradiol were lower in the OB of the MDD female pups than in those of the control female pups. In conclusion, gestational MDD may alter olfactory discrimination performances by affecting neurogenesis, apoptosis and neurosteroidogenesis in OB in a sex-dependent manner. It may be involved in growth retardation through impaired suckling.
Catherine Esnouf, Institut National de la Recherche Agronomique (INRA), Paris,Marie Russel, Institut National de la Recherche Agronomique (INRA), Paris,Nicolas Bricas, Centre de Co-opération Internationale en Recherche Agronomique pour le Développement (CIRAD), Paris
Regional and global food systems are constantly evolving, thus the contextual elements presented in Chapter 1 are likely to evolve, and food systems will be transformed. Because it is impossible to predict the food systems of tomorrow, we have adopted a foresight approach in order to try and understand possible future changes. Our approach, which is presented in the first part of this chapter, has therefore mainly been based on identifying the main drivers of the transformation of food systems. This work was the fruit of collective discussions by a multidisciplinary group made up of some 15 experts. The plurality of their views and their areas of competence allowed them to analyse the potential impacts of the different evolutions identified relative to the sustainability of food systems in terms of their nutritional, economic, social, cultural, environmental and territorial dimensions. This step of the analysis also enabled us to highlight a certain number of points at issue, which are presented in the second part of the chapter; this does not end with a presentation of different scenarios (as might have been expected), but concludes with the three transversal messages arising from debate by this workshop: issues linked to inequalities of access to food, territorial dynamics and the governance of food systems.
Food systems evolving under the effects of various factors
Through the identification of factors underlying the transformation of food systems, it appears clearly that some trends have already been identified (see, in particular, Chapter 1 on the context and the challenges of food systems, and the retrospective analysis described in Chapter 2). Nevertheless, these trends involve a certain number of questions and uncertainties, notably regarding the nature and degree of their potential effects. These uncertainties thus open the way to contrasting scenarios for food systems throughout the world (see Figure 9.1).
The purpose of this paper is to approach stimulated infrared thermography possibilities in terms of measuring longitudinal thermal diffusivity of mural paintings in situ. The measuring method principle is first submitted. It is based on temporal analysis of changes in the characteristic radius beams of spatial profiles of the photothermal signal, measured on the spot of the laser excitation. The feasibility of the method is demonstrated, thanks to a series of simulations. Lastly, the method enables to correctly estimate longitudinal thermal diffusivity in a test sample, and further in a fragment copy of “Saint Christophe” belonging to the Campana collection in the Louvre.
The direct measurement of the radiation pattern of an antenna is often unreachable. A near-field sampling followed by a near-field/far-field (NF/FF) transformation is therefore substituted. This process is, in most cases, applied to antennas placed in free-space or over a perfect electric conductor. On the contrary, few results concern real environment conditions. Nevertheless, it is well known that the nature of the soil can drastically change the radiating characteristic of an antenna. The lack of information about the behavior of the antenna in real conditions can give rise to substantial errors in the evaluation of the performances of electromagnetic devices. The aim of this paper is then to propose a new NF/FF transformation able to reliably supply the field radiated by an antenna placed over a plane, homogeneous, dielectric, and lossy interface. The method is based on the cylindrical-wave expansion of the electric field. The real soil is taken into account by means of its reflection coefficients. First results are given for simple antennas and for both transverse magnetic and transverse electric polarizations.
Several alloys of the Zr65×−yTixAlyCu22Ni13 system were found to be bulk metallic glasses. They have been investigated by DSC and in-situ neutron diffraction. DSC and neutron studies were performed at the same heating rates in order to correlate the evolution of the characteristic temperatures to the crystallization of phases. The first phase appearing at crystallization is dependant on the titanium content, being Zr2Ni for Ti ≈ 5% and a quasi- crystalline phase for Ti ≈ 2.5%. These phases are metastable and transform to Zr2Cu and other phases.
On the last years, gallium nitride (GaN) technology has made a remarked breakthrough in the world of microwave electronics. Power transistors are now available. How this GaN technology would impact space-borne units is now a priority concern. Although the power capability of GaN technology is the first obvious profit, GaN could also be used for other applications like low noise amplifiers, mixers, and probably more. The high sustainable temperature of GaN transistors is most striking advantage for in-flight use. This is connected to packaging design which is also experiencing a lot of activities and quick progresses. Of course, space application is dependent upon the full demonstration of reliability and this constitutes another field of investigation. Finally, after 8 years of GaN studies, experimental results are presented: they open wide the road a revolution inside space-borne electronics: the rise of GaN.
We report on accretion- and outflow-related X-rays from T Tauri stars, based on results from the “XMM-Newton Extended Survey of the Taurus Molecular Cloud.” X-rays potentially form in shocks of accretion streams near the stellar surface, although we hypothesize that direct interactions between the streams and magnetic coronae may occur as well. We report on the discovery of a “soft excess” in accreting T Tauri stars supporting these scenarios. We further discuss a new type of X-ray source in jet-driving T Tauri stars. It shows a strongly absorbed coronal component and a very soft, weakly absorbed component probably related to shocks in microjets. The excessive coronal absorption points to dust-depletion in the accretion streams.
The performance of hand disinfection by staff in a 31-bed department of intensive care was monitored. During 32 hours of observation, 727 opportunities for hand disinfection were observed, and the compliance rate was 27.9%. The level of work experience was not correlated with hand disinfection compliance rates.
French mollusc production is based mainly on the Pacific cupped oyster, Crassostrea gigas. Since 1991, annual mass mortality of juveniles has been reported during summer months. These recurring episodes concern professionals who fear that like Portugese oyster, C. angulata, C. gigas could in turn disappear following one of these epizooties. Previously, bacteriological analysis of moribund oyster juveniles yielded an isolate of a Vibrio splendidus biovar II strain, named TNEMF6. This isolate was demonstrated to be pathogenic to Crassostrea gigas spat by experimental challenge. To study the association between summer oyster mortality and presence of TNEMF6 cluster strains, Vibrionaceae fauna were isolated from infected spat along the French Atlantic coast between 1997-1998. Strains related to V. splendidus biovar II were selected. Comparison with TNEMF6 was performed by classical biochemical tests and polymerase chain reaction – restriction fragment length polymorphism (PCR-RFLP) of SSU rDNA, rpoD, and gyrB genes. Genomic similarities were confirmed by DNA/DNA hybridization. Only one strain out of 14, TNNIII7, was found to be closely related to the pathogenic bacteria. Neither the phenotypic nor the genotypic markers used in this study were able to distinguish pathogenic from non-pathogenic strains of the widespread V. splendidus. However, future genetic comparisons of TNEMF6 and TNNIII7 is likely to reveal genes involved in pathogenicity.
On dit qu'un nombre entier A est hautement composé si tout nombre M plus petit que A a moins de diviseurs que A. Si l'on définit d(n) = nombre de diviseurs de n, on sait que, si la décomposition en facteurs premiers de n est n = Πi piai, on a:
La définition devient: A est hautement composé si et seulement si:
Ramanujan  a défini et étudié les nombres hautement composés, démontrant les propriétés suivantes:
Si A = 2a2 3a3 … pkapk est un nombre hautement composé, on a:
et à l'exception de A = 4 et A = 36, on a: apk = 1 [8, §8].
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