276 research outputs found

    Resolving the microscopic hydrodynamics at the moving contact line

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    The molecular structure of moving contact lines (MCLs) and the emergence of a corresponding macroscopic dissipation have made the MCL a paradigm of fluid dynamics. Through novel averaging techniques that remove capillary waves smearing we achieve an unprecedented resolution in molecular dynamics simulations and find that they match with the continuum description obtained by finite element method down to molecular scales. This allows us to distinguish dissipation at the liquid-solid interface (Navier-slip) and at the contact line, the latter being negligible for the rather smooth substrate considered

    A comparative analysis of the causes of air pollution in three cities of the Danube region: implications for the implementation of the air quality directives

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    The causes of air pollution in three cities of the Danube region (Budapest, Sofia and Zagreb) were studied using datasets of measurements and modelling tools. The contributions from different activity sectors, including natural sources and their geographical origin were quantified. It was observed that most of the pollutants are emitted locally. However, the medium to long range transport may be also considerable. On the basis of the output of the source identification, a series of measures were proposed to deal wtih the pollution problem at local, national and international levels.JRC.H.2-Air and Climat

    Ensemble Inequivalence in Single Molecule Experiments

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    In bulk systems the calculation of the main thermodynamic quantities leads to the same expectation values in the thermodynamic limit, regardless of the choice of the statistical ensemble. Single linear molecules can be still regarded as statistical systems, where the thermodynamic limit is represented by infinitely long chains. The question of equivalence between different ensembles is not at all obvious and has been addressed in the literature, with sometimes contradicting conclusions. We address this problem by studying the scaling properties of the ensemble difference for two different chain models, as a function of the degree of polymerization. By characterizing the scaling behavior of the difference between the isotensional (Gibbs) and isometric (Helmholtz) ensembles in the transition from the low-stretching to the high-stretching regime, we show that ensemble equivalence cannot be reached for macroscopic chains in the low force regime, and we characterize the transition from the inequivalence to the equivalence regime.Comment: Typos in equations fixed. Reference list updated and corrected. Extende

    The withdrawal from oncogenetic counselling and testing for hereditary and familial breast and ovarian cancer. A descriptive study of an Italian sample

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    <p>Abstract</p> <p>Background</p> <p>Oncogenetic counselling is seldom followed through, even when individuals are eligible according to the test criteria. The basic variables which influence the decision to undergo the genetic counselling process are: risk perception, expected benefit or limitations of genetic testing, general psychological distress or cancer-specific distress, lack of trust in one's emotional reactions when faced with negative events, expected level of family support and communications within the family. The aim of this study was to describe the psychosocial variables of an Italian sample that forgoes genetic counselling.</p> <p>Methods</p> <p>From May 2002 to December 2006 a psychological questionnaire was sent out to one hundred and six subjects, who freely requested a first genetic informative consultation, and never asked to have a second visit and the family tree drawn up in order to inquire about their eligibility for genetic testing. Statistical analysis was performed by Pearson chi-square test, t-test and Spearman RHO coefficient.</p> <p>Results</p> <p>The survey presents a lack of emotional cohesion and structured roles and rules within the family system and a positive correlation between the number of children, anxiety and risk perception. The main reasons for giving up on counselling were a sense that testing was a waste of time and the inability to emotionally handle the negative consequences of the test outcome. The subjects who maintained that test and an early diagnosis were a "waste of time" experienced more anxiety.</p> <p>Conclusion</p> <p>The study revealed the importance to ac knowledging the whole persona and their family system as well as provide information highlighting usefulness of early diagnosis.</p

    Properties of the Liquid-Vapor Interface of Acetone-Water Mixtures. A Computer Simulation and ITIM Analysis Study

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    Molecular dynamics simulations of the liquid-vapor interface of acetone-water mixtures of different compositions, covering the entire composition range have been performed on the canonical (N, V, T) ensemble at 298 K, using a model combination that excellently describes the mixing properties of these compounds. The properties of the intrinsic liquid surfaces have been analyzed in terms of the Identification of the Truly Interfacial Molecules (ITIM) method. Thus, the composition, width, roughness, and separation of the subsurface molecular layers, as well as self-association, orientation, and dynamics of exchange with the bulk phase of the surface molecules have been analyzed in detail. Our results show that acetone molecules are strongly adsorbed at the liquid surface, and this adsorption extends to several molecular layers. Like molecules in the surface layer are found to form relatively large lateral self-associates. The effect of the vicinity of the vapor phase on a number of properties of the liquid phase vanishes beyond the first molecular layer, with the second subsurface layer already part of the bulk liquid phase in these respects. The orientational preferences of the surface molecules are governed primarily by the dipole-dipole interaction of the neighboring acetone molecules, and hydrogen bonding interaction of the neighboring acetone-water pairs. (Figure Presented). © 2015 American Chemical Society

    Treatment with Natalizumab in Relapsing–Remitting Multiple Sclerosis Patients Induces Changes in Inflammatory Mechanism

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    Natalizumab is a widely accepted drug for the relapsing–remitting subtype of multiple sclerosis (RRMS). The present longitudinal exploratory study in RRMS patients analyzes the effects of natalizumab treatment on the levels of pro-inflammatory and anti-inflammatory cytokine protein levels and also the frequency and suppressor function of regulatory T cells. Flow cytometry was used to determine cytokines and regulatory T cell frequency while regulatory T cell suppressor function was assayed in vitro at different time-points after starting with natalizumab. Results showed serum levels of pro-inflammatory interferon gamma and interleukin (IL)-12p70, as well as anti-inflammatory IL-4 and IL-10, were elevated just a few hours or days after first IV infusion of natalizumab. Interestingly, other cytokines like IL-5 or IL-13 were also elevated while pro-inflammatory IL-17, IL-2, and IL-1ÎČ increased only after a long-term treatment, suggesting different immune mechanisms. In contrast, we did not observe any effect of natalizumab treatment on regulatory T cell frequency or activity. In conclusion, these results suggest natalizumab has other immunological effects beyond VLA-4 interaction and inhibition of CNS extravasation, the relevance of which is as yet unknown and warrants further investigation

    Epigenetic modification of histone 3 at lysine 9 in sheep zygotes and its relationship with DNA methylation

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    <p>Abstract</p> <p>Background</p> <p>Previous studies indicated that, unlike mouse zygotes, sheep zygotes lacked the paternal DNA demethylation event. Another epigenetic mark, histone modification, especially at lysine 9 of histone 3 (H3K9), has been suggested to be mechanically linked to DNA methylation. In mouse zygotes, the absence of methylated H3K9 from the paternal pronucleus has been thought to attribute to the paternal DNA demethylation.</p> <p>Results</p> <p>By using the immunofluorescence staining approach, we show that, despite the difference in DNA methylation, modification of H3K9 is similar between the sheep and mouse zygotes. In both species, H3K9 is hyperacetylated or hypomethylated in paternal pronucleus relative to maternal pronucleus. In fact, sheep zygotes can also undergo paternal DNA demethylation, although to a less extent than the mouse. Further examinations of individual zygotes by double immunostaining revealed that, the paternal levels of DNA methylation were not closely associated with that of H3K9 acetylation or tri-methylation. Treatment of either 5-azacytidine or Trichostatin A did not induce a significant decrease of paternal DNA methylation levels.</p> <p>Conclusion</p> <p>Our results suggest that in sheep lower DNA demethylation of paternal genomes is not due to the H3K9 modification and the methylated DNA sustaining in paternal pronucleus does not come from DNA <it>de novo </it>methylation.</p

    Subjective versus objective risk in genetic counseling for hereditary breast and/or ovarian cancers

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    Background. Despite the fact that genetic counseling in oncology provides information regarding objective risks, it can be found a contrast between the subjective and objective risk. The aims of this study were to evaluate the accuracy of the perceived risk compared to the objective risk estimated by the BRCApro computer model and to evaluate any associations between medical, demographic and psychological variables and the accuracy of risk perception. Methods. 130 subjects were given medical-demographic file, Cancer and Genetic Risk Perception, Hospital Anxiety-Depression Scale. It was also computed an objective evaluation of the risk by the BRCApro model. Results. The subjective risk was significantly higher than objective risk. The risk of tumour was overestimated by 56%, and the genetic risk by 67%. The subjects with less cancer affected relatives significantly overestimated their risk of being mutation carriers and made a more innacurate estimation than high risk subjects. Conclusion. The description of this sample shows: general overestimation of the risk, inaccurate perception compared to BRCApro calculation and a more accurate estimation in those subjects with more cancer affected relatives (high risk subjects). No correlation was found between the levels of perception of risk and anxiety and depression. Based on our findings, it is worth pursuing improved communication strategies about the actual cancer and genetic risk, especially for subjects at "intermediate and slightly increased risk" of developing an hereditary breast and/or ovarian cancer or of being mutation carrier

    A new mutant genetic resource for tomato crop improvement by TILLING technology

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    <p>Abstract</p> <p>Background</p> <p>In the last decade, the availability of gene sequences of many plant species, including tomato, has encouraged the development of strategies that do not rely on genetic transformation techniques (GMOs) for imparting desired traits in crops. One of these new emerging technology is TILLING (Targeting Induced Local Lesions In Genomes), a reverse genetics tool, which is proving to be very valuable in creating new traits in different crop species.</p> <p>Results</p> <p>To apply TILLING to tomato, a new mutant collection was generated in the genetic background of the processing tomato cultivar Red Setter by treating seeds with two different ethylemethane sulfonate doses (0.7% and 1%). An associated phenotype database, LycoTILL, was developed and a TILLING platform was also established. The interactive and evolving database is available online to the community for phenotypic alteration inquiries. To validate the Red Setter TILLING platform, induced point mutations were searched in 7 tomato genes with the mismatch-specific ENDO1 nuclease. In total 9.5 kb of tomato genome were screened and 66 nucleotide substitutions were identified. The overall mutation density was estimated and it resulted to be 1/322 kb and 1/574 kb for the 1% EMS and 0.7% EMS treatment respectively.</p> <p>Conclusions</p> <p>The mutation density estimated in our collection and its comparison with other TILLING populations demonstrate that the Red Setter genetic resource is suitable for use in high-throughput mutation discovery. The Red Setter TILLING platform is open to the research community and is publicly available via web for requesting mutation screening services.</p

    Evaluation of receptor and chemical transport models for PM10 source apportionment

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    In this study, the performance of two types of source apportionment models was evaluated by assessing the results provided by 40 different groups in the framework of an intercomparison organised by FAIRMODE WG3 (Forum for air quality modelling in Europe, Working Group 3). The evaluation was based on two performance indicators: z-scores and the root mean square error weighted by the reference uncertainty (RMSEu), with pre-established acceptability criteria. By involving models based on completely different and independent input data, such as receptor models (RMs) and chemical transport models (CTMs), the intercomparison provided a unique opportunity for their cross-validation. In addition, comparing the CTM chemical profiles with those measured directly at the source contributed to corroborate the consistency of the tested model results. The most commonly used RM was the US EPA- PMF version 5. RMs showed very good performance for the overall dataset (91% of z-scores accepted) while more difficulties were observed with the source contribution time series (72% of RMSEu accepted). Industrial activities proved to be the most difficult sources to be quantified by RMs, with high variability in the estimated contributions. In the CTMs, the sum of computed source contributions was lower than the measured gravimetric PM10 mass concentrations. The performance tests pointed out the differences between the two CTM approaches used for source apportionment in this study: brute force (or emission reduction impact) and tagged species methods. The sources meeting the z-score and RMSEu acceptability criteria tests were 50% and 86%, respectively. The CTM source contributions to PM10 were in the majority of cases lower than the RM averages for the corresponding source. The CTMs and RMs source contributions for the overall dataset were more comparable (83% of the z-scores accepted) than their time series (successful RMSEu in the range 25% - 34%). The comparability between CTMs and RMs varied depending on the source: traffic/exhaust and industry were the source categories with the best results in the RMSEu tests while the most critical ones were soil dust and road dust. The differences between RMs and CTMs source reconstructions confirmed the importance of cross validating the results of these two families of models
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