Dynamical interferences to probe short-pulse photoassociation of Rb atoms and stabilization of Rb_2 dimers

We analyze the formation of Rb_2 molecules with short photoassociation pulses applied to a cold Rb-85 sample. A pump laser pulse couples a continuum level of the ground electronic state X ^1\Sigma_{g}^+ with bound levels in the 0_{u}^+ (5S+5P_{1/2}) and 0_{u}^+ (5S+5P_{3/2}) vibrational series. The nonadiabatic coupling between the two excited channels induces time-dependent beatings in the populations. We propose to take advantage of these oscillations to design further laser pulses that probe the photoassociation process via photoionization or that optimize the stabilization in deep levels of the ground state.Comment: 4 pages, 5 figures. v2: major changes in introduction, discussion clarified. v3: minor corrections. v4: matches published versio

Sierre, Salgesch et environs: création d'une communauté digitale pour l'oenotourisme

La région de Sierre, Salgesch et Environs a pour objectif d’améliorer la communication de son oenotourisme au travers de son organe de promotion Sierre-Anniviers Marketing. La présente étude démontre de quelle façon la création d’une communauté sur les réseaux sociaux peut répondre aux attentes des entités viticoles de la région. Une enquête réalisée auprès des encaveurs confirme leurs espoirs et attentes envers ces nouveaux supports de communication. Par ailleurs, le benchmark, effectué en profondeur sur Facebook, illustre le potentiel que possèdent les communautés digitales de vin. Il se concentre non seulement sur les régions viticoles européennes (Allemagne, Espagne/Portugal, France, Italie, Suisse), mais également sur le continent américain et l’Australie. Les best practices de ce recensement sont analysés afin de cibler les raisons de leur succès. Puis, à partir du benchmark Facebook, l’étudiant ressort les meilleures pratiques de Twitter, YouTube, Pinterest et Instagram. Tous ces résultats amènent à la création de la communauté oenotouristique de Sierre, Salgesch et Environs : Vinum Montis. La dernière partie du travail s’articule autour du développement et des perspectives d’avenir de cette nouvelle communauté

Apc mutation induces resistance of colonic cells to lipoperoxide-triggered apoptosis induced by faecal water from haem-fed rats

Recent epidemiological studies suggest that high meat intake is associated with promotion of colon cancer linked to haem-iron intake. We previously reported that dietary haem, in the form of either haemoglobin or meat, promotes precancerous lesions in the colon of rats given a low-calcium diet. The mechanism of promotion by haem is not known, but is associated with increased lipid peroxidation in faecal water and strong cytotoxic activity of faecal water on a cancerous mouse colonic epithelial cell line. To better understand the involvement of faecal water components of haem-fed rats in colon cancer promotion, we explored the effect of faecal water on normal (Apc +/+) or premalignant cells (Apc Min/+). Further, we tested if this effect was correlated to lipoperoxidation and 4-hydroxynonenal (HNE). We show here for the first time that heterozygote Apc mutation represents a strong selective advantage, via resistance to apoptosis induction (caspase 3 pathway), for colonic cells exposed to a haem-iron induced lipoperoxidation. The fact that HNE treatment of the cells provoked the same effects as the faecal water of rats fed the haem-rich diet suggests that this compound triggers apoptosis in those cells. We propose that this mechanism could be involved in the promotion of colon carcinogenesis by haem in vivo

Mapping soil and substratum at a very high spatial resolution in the hillslope of Couchey (France)

International audienceIn this work, we present a method based on very high spatial resolution (VHSR) aerial images acquired in the visible domain and that map soil surface diversity at the hillslope scale with a spatial resolution of a few centimeters. This method combines aerial VHSR image classification with local soil sampling. Principal component analysis (PCA) and non-supervised classification was performed on image characteristics to define soil surface characteristic classes (SSC). Then soil surface mapping was combined with soil surface descriptions and soil profiles to define soil types by physical and chemical characteristics. As soil results from parent material alteration, identifying the geological substratum can help to explain the diversity of vineyard soils. The confrontation between soil map and geological map at a 1:10000 scale highlights a good correlation between the geological substratum and soils classes for this hillslope

La pratique de l’Essai chez Hume : une tentative de commercer au mieux avec autrui

Hume, homme de lettres plus que philosophe, s’est efforcé de rendre son œuvre accessible au plus grand nombre, en retravaillant sans cesse la forme de sa pensée. Après l’échec du Traité de la nature humaine, jugé trop dogmatique, il présente ses raisonnements sous la forme plus souple et plus consensuelle d’essais censés être en phase avec l’opinion. Il semblerait alors que pour ce penseur qui s’est perçu avant tout comme un passeur du monde du savoir à celui de la conversation, la recherche de l’adhésion et de l’assentiment d’autrui, par le biais de la sympathie, constitue l’essentiel, pour une philosophie qui se donne comme tâche première, la mise en relation. Toutefois, si la sympathie consiste à ressentir vivement ce que nous imaginons qu’autrui ressent et si l’imagination peut me faire imaginer qu’autrui ressent ce qu’il ne ressent pas, ne suis-je pas nécessairement condamné à me tromper sur autrui, m’obligeant ainsi à de perpétuelles corrections et reprises ? De fait, la sympathie me porte de façon naturelle, en direction d’une famille de pensée ou d’un clan, de façon partiale, m’obligeant sans cesse à un effort de rectification, pour que j’étende au-delà du cercle limité de mes proches ce que ma sympathie se contentait de considérer. En d’autres termes, l’essai en tant que promesse d’une transformation à venir, d’un ajustement à accomplir, d’une extension de la sympathie à obtenir, paraît être le passage nécessaire et obligé d’une pensée axée sur la rencontre avec autrui. Mais alors, la pensée humienne ne court-elle pas le risque de ne pas transformer l’essai tenté par la sympathie ?Relating David Hume with the idea of the Essay is very fitting since Hume’s efforts are two-fold. Firstly, he strived to make his philosophy readable and accessible to his readers. In order to achieve that goal, he never refrained from correcting or rephrasing his ideas according to a process of trial and error which was aimed at confirming and substantiating his claims. Then, taking for granted human sociability, he relentlessly endeavored to help his fellow citizens. His relationship with Rousseau was an illustration of his attempts to support people in difficult predicaments. But if in comparison, it is easier to redraft a work, trying to maintain a stable relationship with people is much more complicated. The scope of sympathy is more limited than expected since we tend only to sympathize with people who are close or similar to us. Despite good intentions, trying to connect with people who are too different from us is a hopeless effort and is bound to fail no matter how hard we try. Sympathy is in itself a problem since it leads us into a world of simplifications in which it seems that we all look alike. So in order to be in touch with reality and with his audience, Hume never stopped transforming his work and his attitudes. Nevertheless, is there not a price to pay? We may wonder if Hume’s philosophy has ever achieved stability and if the best it can achieve is a state of flux. Is this state, being in a difficult equilibrium, not bound to change according to the moods of his powerful readers or to the latest dominant ideas

Increasing the stability of sacB transcript improves levansucrase production in Bacillus subtilis.

Aims: To develop a strategy to increase the stability of transcripts of structural genes expressed under the control of sacR, the leader region of Bacillus subtilis levansucrase gene. Methods and Results: Insertion of Shine Dalgarno like sequences in the 5'-untranslated sacR region controlling the expression of sacB. Depending on the number of stabilizing sequences inserted and the position of these sequences with respect to the translation start codon, it was observed that the mRNA stability and the final protein production could be increased or decreased. Conclusions: This mRNA stabilization can be used to increase exocellular protein production in the degU32 (Hy) mutant. Significance and Impact of the Study: This approach can be applied to the expression of heterologous genes of biotechnological interest

Genetic isolation by distance and landscape connectivity in the American marten ( Martes americana )

Empirical studies of landscape connectivity are limited by the difficulty of directly measuring animal movement. ‘Indirect' approaches involving genetic analyses provide a complementary tool to ‘direct' methods such as capture-recapture or radio-tracking. Here the effect of landscape on dispersal was investigated in a forest-dwelling species, the American marten (Martes americana) using the genetic model of isolation by distance (IBD). This model assumes isotropic dispersal in a homogeneous environment and is characterized by increasing genetic differentiation among individuals separated by increasing geographic distances. The effect of landscape features on this genetic pattern was used to test for a departure from spatially homogeneous dispersal. This study was conducted on two populations in homogeneous vs. heterogeneous habitat in a harvested boreal forest in Ontario (Canada). A pattern of IBD was evidenced in the homogeneous landscape whereas no such pattern was found in the near-by harvested forest. To test whether landscape structure may be accountable for this difference, we used effective distances that take into account the effect of landscape features on marten movement instead of Euclidean distances in the model of isolation by distance. Effective distances computed using least-cost modeling were better correlated to genetic distances in both landscapes, thereby showing that the interaction between landscape features and dispersal in Martes americana may be detected through individual-based analyses of spatial genetic structure. However, the simplifying assumptions of genetic models and the low proportions in genetic differentiation explained by these models may limit their utility in quantifying the effect of landscape structur

Autogenous modulation of the Bacillus subtilis sacB-levB-yveA levansucrase operon by levB transcript.

Silencing of levB, the second structural gene of the tricistronic levansucrase operon encoding the endolevanase LevB, decreases the level of levansucrase expression. Conversely, independent expression of levB greatly stimulates operon expression in Bacillus subtilis. This autogenous effect is mediated by the levB transcript, which carries an internal sequence (5'-AAAGCAGGCAA-3') involved in the enhancing effect. In vitro, the levB transcript displays an affinity to the N-terminal fragment of SacY (KD 0.2 µM), the regulatory protein that prevents transcription termination of levansucrase operon. This positive feed back loop leads to an increase in the operon expression when B. subtilis is growing in the presence of high sucrose concentrations. Under these conditions, extracellular levan synthesized by the fructosyl polymerase activity of levansucrase can be degraded mainly into levanbiose by the action of LevB. Levanbiose is neither taken up nor metabolized by the bacteria. This work modifies the present view of the status of levansucrase in B. subtilis physiology