710 research outputs found

    Template-stripped gold surfaces with 0.4 nm rms roughness suitable for force measurements. Application to the Casimir force in the 20-100 nm range

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    Using a template-stripping method, macroscopic gold surfaces with root-mean-square (rms) roughness less than 0.4 nm have been prepared, making them useful for studies of surface interactions in the nanometer range. The utility of such substrates is demonstrated by measurements of the Casimir force at surface separations between 20 and 100 nm, resulting in good agreement with theory. The significance and quantification of this agreement is addressed, as well as some methodological aspects regarding the measurement of the Casimir force with high accuracy.Comment: 7 figure

    Analytical method validation for in vitro permeation of Calendula officinalis L. gel

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    The objective of this study was to evaluate preliminary stability, as well as to validate an analytical method for in vitro skin permeation study of a gel containing tincture of Calendula officinalis L., aiming at the implementation and consolidation of methodologies to be used as prototype for future development of herbal medicine in the Brazilian Amazon region. The gel showed a satisfactory result during the assessment of its preliminary stability considering that the formulation remained stable throughout cycles at temperatures of 45 °C and 25 °C. Parameters obtained in the validation of the analytical method presented satisfactory results for specificity, linearity (r > 0.99), precision (intra-day and inter-day) with relative standard deviation values (R.S.D. %) below the required maximum of 5 %. Accuracy and robustness were consistent with both the objectives of the work and recommendations of the existing laws, providing the reliability of the data obtained during the skin permeation study, evidenced by the gel tendency to promote the permeation of flavonoids, expressed in rutin, through models of synthetic and biological membrane. However, it was observed that the gel had a higher permeability ratio through synthetic membrane, due to greater cumulative mass of rutin quantified after permeation.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Safety and Immunogenicity of a Recombinant Adenovirus Serotype 35-Vectored HIV-1 Vaccine in Adenovirus Serotype 5 Seronegative and Seropositive Individuals.

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    BACKGROUND: Recombinant adenovirus serotype 5 (rAd5)-vectored HIV-1 vaccines have not prevented HIV-1 infection or disease and pre-existing Ad5 neutralizing antibodies may limit the clinical utility of Ad5 vectors globally. Using a rare Ad serotype vector, such as Ad35, may circumvent these issues, but there are few data on the safety and immunogenicity of rAd35 directly compared to rAd5 following human vaccination. METHODS: HVTN 077 randomized 192 healthy, HIV-uninfected participants into one of four HIV-1 vaccine/placebo groups: rAd35/rAd5, DNA/rAd5, and DNA/rAd35 in Ad5-seronegative persons; and DNA/rAd35 in Ad5-seropositive persons. All vaccines encoded the HIV-1 EnvA antigen. Antibody and T-cell responses were measured 4 weeks post boost immunization. RESULTS: All vaccines were generally well tolerated and similarly immunogenic. As compared to rAd5, rAd35 was equally potent in boosting HIV-1-specific humoral and cellular immunity and responses were not significantly attenuated in those with baseline Ad5 seropositivity. Like DNA, rAd35 efficiently primed rAd5 boosting. All vaccine regimens tested elicited cross-clade antibody responses, including Env V1/V2-specific IgG responses. CONCLUSIONS: Vaccine antigen delivery by rAd35 is well-tolerated and immunogenic as a prime to rAd5 immunization and as a boost to prior DNA immunization with the homologous insert. Further development of rAd35-vectored prime-boost vaccine regimens is warranted

    The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

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    Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect

    Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope

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    Nearby clusters and groups of galaxies are potentially bright sources of high-energy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than ~200 GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits exclude large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gamma-ray flux by a factor of ~5 over a smooth-halo assumption. We also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. In this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.Comment: accepted to JCAP, Corresponding authors: T.E. Jeltema and S. Profumo, minor revisions to be consistent with accepted versio

    Physicochemical and phytochemical control of Arrabidaea chica (H. & B.) Verlot leaf powder and standardized tincture

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    The quality control of herbal drugs and their intermediates is essential, especially when they are used as feedstock for medicine development. This study aimed at applying the methodologies established by Brazilian legislation for the development of parameters concerning the characterization and quality control of leaf powder and tincture of Arrabidaea chica (H & B) Verlot. Known as cipó-pau (vinestick), carajeru, pariri, among others, it presents antifungal activity and is used in several diseases such as mycosis and ringworm. The physico-chemical characteristics of the plant drug. The phytochemical screening of the t inc tur e indi cat ed the pr e s enc e of r educ ing sugar s , anthocyanidins , anthocyanins , anthraquinones, steroids, triterpenoids, phenols, flavanonols, flavanols, flavanones, saponins and tannins catechists. HPLC chromatograms showed peaks at 275 nm and 290 nm, with Rt of 8.91 and 13.57 min, whose corresponding spectra showed absorption maxima which is characteristic of flavones and biflavonols -283 nm and 334 nm. Some metabolites found in the phytochemical screening and detected by HPLC may justify the popular use of A. chica as antimicrobial and antifungal medicine.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Improved Cryptanalysis of Skein

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    The hash function Skein is the submission of Ferguson et al. to the NIST Hash Competition, and is arguably a serious candidate for selection as SHA-3. This paper presents the rst third-party analysis of Skein, with an extensive study of its main component: the block cipher Three sh. We notably investigate near collisions, distinguishers, impossible di erentials, key recovery using related-key di erential and boomerang attacks. In particular, we present near collisions on up to 17 rounds, an impossible di erential on 21 rounds, a related-key boomerang distinguisher on 34 rounds, a known-related-key boomerang distinguisher on 35 rounds, and key recovery attacks on up to 32 rounds, out of 72 in total for Threefish-512. None of our attacks directly extends to the full Skein hash. However, the pseudorandomness of Threefish is required to validate the security proofs on Skein, and our results conclude that at least 3

    Transitory Microbial Habitat in the Hyperarid Atacama Desert

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    Traces of life are nearly ubiquitous on Earth. However, a central unresolved question is whether these traces always indicate an active microbial community or whether, in extreme environments, such as hyperarid deserts, they instead reflect just dormant or dead cells. Although microbial biomass and diversity decrease with increasing aridity in the Atacama Desert, we provide multiple lines of evidence for the presence of an at times metabolically active, microbial community in one of the driest places on Earth. We base this observation on four major lines of evidence: a physico-chemical characterization of the soil habitability after an exceptional rain event, identified biomolecules indicative of potentially active cells [e.g., presence of ATP, phospholipid fatty acids (PLFAs), metabolites, and enzymatic activity], measurements of in situ replication rates of genomes of uncultivated bacteria reconstructed from selected samples, and microbial community patterns specific to soil parameters and depths. We infer that the microbial populations have undergone selection and adaptation in response to their specific soil microenvironment and in particular to the degree of aridity. Collectively, our results highlight that even the hyperarid Atacama Desert can provide a habitable environment for microorganisms that allows them to become metabolically active following an episodic increase in moisture and that once it decreases, so does the activity of the microbiota. These results have implications for the prospect of life on other planets such as Mars, which has transitioned from an earlier wetter environment to today's extreme hyperaridity. [Abstract copyright: Copyright © 2018 the Author(s). Published by PNAS.
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