882 research outputs found

    Class II ADP-ribosylation factors are required for efficient secretion of Dengue viruses

    Get PDF
    This article is available open access through the publisher’s website.Identification and characterization of virus-host interactions are very important steps toward a better understanding of the molecular mechanisms responsible for disease progression and pathogenesis. To date, very few cellular factors involved in the life cycle of flaviviruses, which are important human pathogens, have been described. In this study, we demonstrate a crucial role for class II Arf proteins (Arf4 and Arf5) in the dengue flavivirus life cycle. We show that simultaneous depletion of Arf4 and Arf5 blocks recombinant subviral particle secretion for all four dengue serotypes. Immunostaining analysis suggests that class II Arf proteins are required at an early pre-Golgi step for dengue virus secretion. Using a horseradish peroxidase protein fused to a signal peptide, we show that class II Arfs act specifically on dengue virus secretion without altering the secretion of proteins through the constitutive secretory pathway. Co-immunoprecipitation data demonstrate that the dengue prM glycoprotein interacts with class II Arf proteins but not through its C-terminal VXPX motif. Finally, experiments performed with replication-competent dengue and yellow fever viruses demonstrate that the depletion of class II Arfs inhibits virus secretion, thus confirming their implication in the virus life cycle, although data obtained with West Nile virus pointed out the differences in virus-host interactions among flaviviruses. Our findings shed new light on a molecular mechanism used by dengue viruses during the late stages of the life cycle and demonstrate a novel function for class II Arf proteins.Research Fund for Control of Infectious Diseases of Hong Kong and BNP Paribas Corporate and Investment Banking

    Beyond Worst-Case Analysis for Joins with Minesweeper

    Full text link
    We describe a new algorithm, Minesweeper, that is able to satisfy stronger runtime guarantees than previous join algorithms (colloquially, `beyond worst-case guarantees') for data in indexed search trees. Our first contribution is developing a framework to measure this stronger notion of complexity, which we call {\it certificate complexity}, that extends notions of Barbay et al. and Demaine et al.; a certificate is a set of propositional formulae that certifies that the output is correct. This notion captures a natural class of join algorithms. In addition, the certificate allows us to define a strictly stronger notion of runtime complexity than traditional worst-case guarantees. Our second contribution is to develop a dichotomy theorem for the certificate-based notion of complexity. Roughly, we show that Minesweeper evaluates ÎČ\beta-acyclic queries in time linear in the certificate plus the output size, while for any ÎČ\beta-cyclic query there is some instance that takes superlinear time in the certificate (and for which the output is no larger than the certificate size). We also extend our certificate-complexity analysis to queries with bounded treewidth and the triangle query.Comment: [This is the full version of our PODS'2014 paper.

    Real-world Experience With Sunitinib Treatment in Patients With Metastatic Renal Cell Carcinoma: Clinical Outcome According to Risk Score.

    Get PDF
    BACKGROUND: ADONIS is an ongoing observational study in 9 European countries, designed to evaluate treatment patterns/outcomes in patients with metastatic renal cell carcinoma (mRCC) treated with first-line sunitinib and/or second-line axitinib post sunitinib. We present an evaluation of sunitinib efficacy by risk group, in the real-world setting examined in ADONIS. PATIENTS AND METHODS: Patients were enrolled at the start of first-line sunitinib treatment or second-line axitinib post sunitinib treatment. Evaluation of sunitinib efficacy was assessed by International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) and Memorial Sloan Kettering Cancer Center risk criteria. RESULTS: For all patients in this analysis (N = 467), the median progression-free survival was 23.8 months (95% confidence interval [CI], 16.5-28.5 months), 11.8 months (95% CI, 8.1-17.4 months), and 4.6 months (95% CI, 2.5-7.7 months) for IMDC favorable-, intermediate-, and poor-risk groups, respectively. The median overall survival was 97.1 months (95% CI, 46.3 months-not evaluable [NE]), 33.5 months (95% CI, 20.5-46.6 months), and 10.0 months (95% CI, 4.5-19.8 months) for the respective risk groups. Data on individual risk factors were available for a subgroup of patients, allowing analysis by intermediate risk by 1 versus 2 risk factors. When including this subgroup (n = 120), the median overall survival for IMDC favorable-, intermediate-1, and intermediate-2 risk factors was 21.6 months (95% CI, 16.3 months-NE), 20.5 months (15.5 months-NE), and 15.1 months (4.1 months-NE), respectively. CONCLUSIONS: For patients overall and by risk-group stratification, survival estimates were aligned with previously published data. In patients with intermediate-1 risk, overall survival was very similar to patients with favorable risk. However, further exploration of outcome data from different sources is needed to confirm these observations

    Membrane patterned by pulsed laser micromachining for proton exchange membrane fuel cell with sputtered ultra-low catalyst loadings

    Get PDF
    International audienceProton exchange membranes were nano-and micro-patterned on their cathode side by pressing them against stainless steel molds previously irradiated by a Ti:Sapphire femtosecond laser. The membranes were associated to ultra-low loaded thin catalytic layers (25 ”gPt cm-2) prepared by plasma magnetron sputtering. The Pt catalyst was sputtered either on the membrane or on the porous electrode. The fuel cell performance in dry conditions were found to be highly dependent on the morphology of the membrane surface. When nanometric ripples covered by a Pt catalyst were introduced on the surface of the membrane, the fuel cell outperformed the conventional one with a flat membrane. By combining nano-and micro-patterns (nanometric ripples and 11-24 ”m deep craters), the performance of the cells was clearly enhanced. The maximum power density achieved by the fuel cell was multiplied by a factor of 3.6 (at 50 °C and 3 bars): 438 mW cm-2 vs 122 mW cm-2. This improvement is due to high catalyst utilization with a high membrane conductivity. When Pt is sputtered on the porous electrode (and not on the membrane), the contribution of the patterned membrane to the fuel cell efficiency was less significant, except in the presence of nanometric ripples. This result suggests that the patterning of the membrane must be consistent with the way the catalyst is synthesized, on the membrane or on the porous electrode

    A High-Resolution Atlas of Uranium-Neon in the H Band

    Full text link
    We present a high-resolution (R ~ 50 000) atlas of a uranium-neon (U/Ne) hollow-cathode spectrum in the H-band (1454 nm to 1638 nm) for the calibration of near-infrared spectrographs. We obtained this U/Ne spectrum simultaneously with a laser-frequency comb spectrum, which we used to provide a first-order calibration to the U/Ne spectrum. We then calibrated the U/Ne spectrum using the recently-published uranium line list of Redman et al. (2011), which is derived from high-resolution Fourier transform spectrometer measurements. These two independent calibrations allowed us to easily identify emission lines in the hollow cathode lamp that do not correspond to known (classified) lines of either uranium or neon, and to compare the achievable precision of each source. Our frequency comb precision was limited by modal noise and detector effects, while the U/Ne precision was limited primarily by the signal-to-noise ratio (S/N) of the observed emission lines and our ability to model blended lines. The standard deviation in the dispersion solution residuals from the S/N-limited U/Ne hollow cathode lamp were 50% larger than the standard deviation of the dispersion solution residuals from the modal-noise-limited laser frequency comb. We advocate the use of U/Ne lamps for precision calibration of near-infrared spectrographs, and this H-band atlas makes these lamps significantly easier to use for wavelength calibration.Comment: 23 pages, 7 figures, submitted and accepted in ApJSS. Online-only material to be published online by ApJS

    The Significance of Energy Storage for Renewable Energy Generation and the Role of Instrumentation and Measurement

    Get PDF
    International audienceEnergy storage is not a new concept but is currently getting increasing importance in the context of energy transition paradigm. Indeed, it is expected to play a key role as an enabling technology for lowering the carbon footprint of the electric power system. In fact, the growing development of renewable energy resources and their increasing share in the energy mix, are introducing significant challenges to the existing power grid due to the high variability of these sources/loads. In particular, maintaining the generation-consumption balance of the electric power in real time, as well as the overall power system security, when these special energy sources/loads are present at a significant scale is a major concern. With competitive energy storage, it will be possible to introduce more flexibility in the electrical system thus helping it to better manage the overall energy balance with better system response in case of severe contingencies. Energy storage technologies were historically used for managing the load curve while observing generation dynamic constraints. The most well-known storage technology is the pumped hydro storage where the energy is stored in a hydraulic form (water potential energy). With the event of open access and the corresponding unbundling of electric power industry segments, valorizing energy storage options under market conditions has become tricky. The major present barriers for deploying energy storage systems (ESS) are high cost, competitive economic value, efficiency and energy density, together with energy policies. The new energy paradigm has put a new emphasis on energy storage, and many research roadmaps have pointed out the need for overcoming the current barriers. The decision makers' awareness of the importance of energy storage is also on the rise. However, adequate incentives for encouraging massive deployment of ESS and storage technology within the electric power system are still lacking. Currently, most of the effort is dedicated to in situ demonstration projects in striving for smarter grids and support of innovations with the corresponding proofs of concept and feedback experience. Additionally, different grid applications are assessed for both centralized to decentralized uses. Various energy storage applications for frequency regulation, voltage support, investment optimization, or peak shaving are under consideration. In this article, some of the main energy storage technologies will be reviewed according to their main application domains. That will be followed by a focus on battery energy storage. Some key elements of battery management system (BMS) technologies and ESS architecture and characterization will be addressed. Then some aspects of ESS protection will be presented and the key trends and indications of emerging concepts for energy storage will be identified

    Quelle R&D Mener pour le DĂ©veloppement Des RĂ©seaux D'Ă©nergie De Demain ? Les Propositions de L'ancre en 2015

    Get PDF
    Feuille de route sur les rĂ©seaux Ă©lectriques et stockage Ă©laborĂ©e par le GP10 RĂ©seaux et Stockages de l'Energie de l'ANCRECette feuille de route concerne les rĂ©seaux d’énergie Ă©lectrique, de chaleur et de froid, les rĂ©seaux de gaz (hydrogĂšne, gaz naturel), leurs stockages associĂ©s, ainsi que leurs couplages Ă  venir dans le cadre de la transition Ă©nergĂ©tique et des Ă©volutionsqui l’accompagneront, que ce soit sur les modes de production d’énergie ou sur l’évolution des usages.Le focus est portĂ© sur les rĂ©seaux Ă©lectriques qui seront les premiers impactĂ©s par cette transition Ă©nergĂ©tique. Hormisquelques Ă©lĂ©ments trĂšs spĂ©cifiques aux rĂ©seaux Ă©lectriques (et qui seront notĂ©s dans le texte par une couleur diffĂ©rente)il est Ă  souligner que la quasi-totalitĂ© des considĂ©rations et axes de R&D Ă©voquĂ©s pour les rĂ©seauxĂ©lectriques et le dĂ©veloppement de leur « intelligence » et/ou de leur flexibilitĂ© s’appliquentĂ©galement aux autres rĂ©seaux d’énergie. Par ailleurs, si le groupe programmatique« RĂ©seaux et Stockage » de l’ANCRE (GP10) s’est largement appuyĂ© sur les nombreuses feuilles de route Ă©mises tant au niveau national, dont celles de l’ADEME, qu’europĂ©en, il a Ă©galement souhaitĂ© s’en dĂ©marquer en insistantlargement et en dĂ©taillant les recherches scientifiques et technologiques Ă  mener face aux verrous actuellement identifiĂ©s

    Improved Laboratory Transition Probabilities for Neutral Chromium and Re-determination of the Chromium Abundance for the Sun and Three Stars

    Full text link
    Branching fraction measurements from Fourier transform spectra in conjunction with published radiative lifetimes are used to determine transition probabilities for 263 lines of neutral chromium. These laboratory values are employed to derive a new photospheric abundance for the Sun: log Ï”\epsilon(Cr I)⊙_{\odot} = 5.64±\pm0.01 (σ=0.07\sigma = 0.07). These Cr I solar abundances do not exhibit any trends with line strength nor with excitation energy and there were no obvious indications of departures from LTE. In addition, oscillator strengths for singly-ionized chromium recently reported by the FERRUM Project are used to determine: log Ï”\epsilon(Cr II)⊙_{\odot} = 5.77±\pm0.03 (σ=0.13\sigma = 0.13). Transition probability data are also applied to the spectra of three stars: HD 75732 (metal-rich dwarf), HD 140283 (metal-poor subgiant), and CS 22892-052 (metal-poor giant). In all of the selected stars, Cr I is found to be underabundant with respect to Cr II. The possible causes for this abundance discrepancy and apparent ionization imbalance are discussed.Comment: 44 pages, 6 figure
    • 

    corecore