307 research outputs found

    High efficiency symmetric beam splitter for cold atoms with a standing wave light pulse sequence

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    In a recent experiment [1], it was observed that a sequence of two standing wave square pulses can split a BEC at rest into +/- 2 h_bar k diffraction orders with almost 100% efficiency. By truncating the Raman-Nath equations to a 2-state model, we provide an intuitive picture that explains this double square pulse beamsplitter scheme. We further show it is possible to optimize a standingwave multi square pulse sequence to efficiently diffract an atom at rest to symmetric superposition of +/- 2n h_bar k diffraction order with n>1. The approach is considered to be qualitatively different from the traditional light pulse schemes in the Bragg or the Raman-Nath region, and can be extended to more complex atomic optical elements that produce various tailored output momentum states from a cold atom source.Comment: 22 pages, 4 figures, 1 tabl

    Interactions with M cells and macrophages as key steps in the pathogenesis of enterohemorrhagic Escherichia coli infections

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    Enterohemorrhagic Escherichia coli (EHEC) are food-borne pathogens that can cause serious infections ranging from diarrhea to hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). Translocation of Shiga-toxins (Stx) from the gut lumen to underlying tissues is a decisive step in the development of the infection, but the mechanisms involved remain unclear. Many bacterial pathogens target the follicle-associated epithelium, which overlies Peyer's patches (PPs), cross the intestinal barrier through M cells and are captured by mucosal macrophages. Here, translocation across M cells, as well as survival and proliferation of EHEC strains within THP-1 macrophages were investigated using EHEC O157:H7 reference strains, isogenic mutants, and 15 EHEC strains isolated from HC/HUS patients. We showed for the first time that E. coli O157:H7 strains are able to interact in vivo with murine PPs, to translocate ex vivo through murine ileal mucosa with PPs and across an in vitro human M cell model. EHEC strains are also able to survive and to produce Stx in macrophages, which induce cell apoptosis and Stx release. In conclusion, our results suggest that the uptake of EHEC by M cells and underlying macrophages in the PP may be a critical step in Stx translocation and release in vivo. A new model for EHEC infection in humans is proposed that could help in a fuller understanding of EHEC-associated diseases

    Measurement and analysis of single-hop delay on an IP backbone network

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    Pressure Sores Prevention for Paraplegic People: Effects of Visual, Auditory and Tactile Supplementations on Overpressures Distribution in Seated Posture

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    This paper presents a study on the usage of different informative modalities as biofeedbacks of a perceptual supplementation device aiming at reducing overpressure at the buttock area. Visual, audio and lingual electrotactile modalities are analysed and compared with a non-biofeedback session. In conclusion, sensory modalities have a positive and equal effect, but they are not equally judged in terms of comfort and disturbance with some other activities

    Risk factors for death and the 3-year survival of patients with systemic sclerosis: the French ItinérAIR-Sclérodermie study

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    Objectives. This longitudinal study investigated survival, risk factors and causes of death in the multicentre ItinérAIR-Sclérodermie cohort of patients with SSc without severe pulmonary fibrosis or severe left heart disease at baseline

    Aérosols de médicaments

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    L\u27aérosolthérapie a bénéficié ces dernières années de progrès technologiques considérables au niveau des générateurs d\u27aérosols. Les aérosols doseurs liquides HFA avec ou sans chambre d\u27inhalation, les aérosols doseurs de poudre ont vu leurs indications respectives précisées. Les systèmes de nébulisation ont également progressé avec notamment l\u27apparition des nébuliseurs à membranes. La nébulisation permet de traiter les formes les plus sévères des maladies repiratoires, asthme, BPCO, mucoviscidose, par les bronchodilatateurs, les corticoïdes, les antibiotiques et la rhDNase I. L\u27utilisation de la nébulisation trouve depuis peu des applications pour le traitement de maladies systémiques telles que le diabète ou l\u27hypertension artérielle pulmonaire. Des perspectives apparaissent également pour la chimiothérapie antitumorale et la vaccination par aérosols. Les conditions optimales de prescription, d\u27administration et de suivi de l\u27aérosolthérapie ont été définies

    Inter-Destination Multimedia Synchronization; Schemes, Use Cases and Standardization

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    Traditionally, the media consumption model has been a passive and isolated activity. However, the advent of media streaming technologies, interactive social applications, and synchronous communications, as well as the convergence between these three developments, point to an evolution towards dynamic shared media experiences. In this new model, geographically distributed groups of consumers, independently of their location and the nature of their end-devices, can be immersed in a common virtual networked environment in which they can share multimedia services, interact and collaborate in real-time within the context of simultaneous media content consumption. In most of these multimedia services and applications, apart from the well-known intra and inter-stream synchronization techniques that are important inside the consumers playout devices, also the synchronization of the playout processes between several distributed receivers, known as multipoint, group or Inter-destination multimedia synchronization (IDMS), becomes essential. Due to the increasing popularity of social networking, this type of multimedia synchronization has gained in popularity in recent years. Although Social TV is perhaps the most prominent use case in which IDMS is useful, in this paper we present up to 19 use cases for IDMS, each one having its own synchronization requirements. Different approaches used in the (recent) past by researchers to achieve IDMS are described and compared. As further proof of the significance of IDMS nowadays, relevant organizations (such as ETSI TISPAN and IETF AVTCORE Group) efforts on IDMS standardization (in which authors have been and are participating actively), defining architectures and protocols, are summarized.This work has been financed, partially, by Universitat Politecnica de Valencia (UPV), under its R&D Support Program in PAID-05-11-002-331 Project and in PAID-01-10, and by TNO, under its Future Internet Use Research & Innovation Program. The authors also want to thank Kevin Gross for providing some of the use cases included in Sect. 1.2.Montagud, M.; Boronat Segui, F.; Stokking, H.; Van Brandenburg, R. (2012). Inter-Destination Multimedia Synchronization; Schemes, Use Cases and Standardization. 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    Ribosomal RNA 2′O-methylation as a novel layer of inter-tumour heterogeneity in breast cancer

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    International audienceRecent epitranscriptomics studies unravelled that ribosomal RNA (rRNA) 2′O-methylation is an additional layer of gene expression regulation highlighting the ribosome as a novel actor of translation control. However, this major finding lies on evidences coming mainly, if not exclusively, from cellular models. Using the innovative next-generation RiboMeth-seq technology, we established the first rRNA 2′O-methylation landscape in 195 primary human breast tumours. We uncovered the existence of compulsory/stable sites, which show limited inter-patient variability in their 2′O-methylation level, which map on functionally important sites of the human ribosome structure and which are surrounded by variable sites found from the second nucleotide layers. Our data demonstrate that some positions within the rRNA molecules can tolerate absence of 2′O-methylation in tumoral and healthy tissues. We also reveal that rRNA 2′O-methylation exhibits intra- and inter-patient variability in breast tumours. Its level is indeed differentially associated with breast cancer subtype and tumour grade. Altogether, our rRNA 2′O-methylation profiling of a large-scale human sample collection provides the first compelling evidence that ribosome variability occurs in humans and suggests that rRNA 2′O-methylation might represent a relevant element of tumour biology useful in clinic. This novel variability at molecular level offers an additional layer to capture the cancer heterogeneity and associates with specific features of tumour biology thus offering a novel targetable molecular signature in cancer
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