204 research outputs found

    The Influence of the Passive Earth Pressure and other Factors on the Stability of the Underground Masonry Vaults of the Paris Metro

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    The paper introduces the main concepts and criteria presented in the Guidelines on the Analysis, Conservation and Structural Restoration elaborated by the ICOMOS/ISCARSAH committee. The guidelines have been developed with the aim to provide guidance to experts and practitioners working in the study and conservation of structures or the architectural heritage. The guidelines are based on the ICOMOS Charter on the Principles for he Analysis, Conservation and Structural Restoration of Architectural Heritage elaborated by ISCARSAH and adopted by ICOMOS in 2003. The guidelines are intended to assist the multidisciplinary teams involved in the management of historical structures across all the stages of the study and operation, including the investigation and documentation works, the structural verification and the selection and design of appropriate minimum interventions

    Chapter X: The Tour de France: a success story in spite of competitive imbalance and doping

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    International audienceThe chapter goes as follows. In the first section it is demonstrated how the Tour de France is a high quality product. This is a result from its accurate design, its management, its economic model and its finance structure, both in comparison to other mega-sporting events and with reference to tournament theory. It is not easy to assess the competitive balance in the Tour de France since, as was demonstrated in chapter 10, it is at the same time an individual and a team sport contest. After reviewing some results published in literature so far, a new metrics for evaluating competitive balanced in the Tour de France is presented in section 2. Finally, the Tour de France cannot ignore doping as a potential threat to fan attendance and TV viewing. We therefore discuss the issue of doping and a new procedure to deal with doping in section 3

    HSPG-Binding Peptide Corresponding to the Exon 6a-Encoded Domain of VEGF Inhibits Tumor Growth by Blocking Angiogenesis in Murine Model

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    Vascular endothelial growth factor VEGF165 is a critical element for development of the vascular system in physiological and pathological angiogenesis. VEGF isoforms have different affinities for heparan sulphate proteoglycan (HSPG) as well as for VEGF receptors; HSPGs are important regulators in vascular development. Therefore, inhibition of interactions between VEGF and HSPGs may prevent angiogenesis. Here, we demonstrate that an HSPG-binding synthetic peptide, corresponding to exon 6a-encoded domain of VEGF gene, has anti-angiogenic property. This 20 amino acids synthetic peptide prevents VEGF165 binding to several different cell types, mouse embryonic sections and inhibits endothelial cell migration, despite its absence in VEGF165 sequence. Our in vivo anti-tumor studies show that the peptide inhibits tumor growth in both mouse Lewis-Lung Carcinoma and human Liposarcoma tumor-bearing animal models. This is the first evidence that a synthetic VEGF fragment corresponding to exon 6a has functional antagonism both in vitro and in vivo. We conclude that the above HPSG binding peptide (6a-P) is a potent inhibitor of angiogenesis-dependent diseases

    The lived experiences of experienced Vipassana Mahasi meditators: an interpretative phenomenological analysis.

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    Research into the effects and mechanisms of mindfulness training draws predominantly on quantitative research. There is a lack of understanding about the subjective experiences of experienced mindfulness meditators, which may provide additional insights into the effects, processes and context of mindfulness training. This qualitative study explored the lived experiences of a novel group of experienced mindfulness meditators who practise Vipassana Mahasi (VM) meditation. The study aimed to understand how experienced VM practitioners make sense of the effects of practice and what processes they ascribe to it. Participants attended semistructured interviews, and their responses were analysed using interpretative phenomenological analysis. Results yielded overarching themes including (a) improvements in hedonic and eudaimonic well-being; (b) insights into self, others and perception of reality; (c) attaining equanimity; and (d) physical and interpersonal difficulties. Participants perceived VM as a ‘cleansing’ process whereby maladaptive responses were eliminated through mindfulness, other supportive mental qualities, decentering and nonattachment. The findings revealed a complex and dynamic set of interdependent outcomes and processes, which are reinforced by Buddhist teachings and ethical practices. This study highlights the need for additional interdisciplinary research into topics such as insight generation and supportive mental qualities cultivated during VM, novel states of well-being informed by Buddhist constructs and interpersonal difficulties related to long-term practice. Findings also suggest that incorporating Buddhist teachings and ethics into mindfulness-based interventions may enhance practitioner understanding and implementation of meditation techniques.N/

    An empirical examination of the factor structure of compassion

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    Compassion has long been regarded as a core part of our humanity by contemplative traditions, and in recent years, it has received growing research interest. Following a recent review of existing conceptualisations, compassion has been defined as consisting of the following five elements: 1) recognising suffering, 2) understanding the universality of suffering in human experience, 3) feeling moved by the person suffering and emotionally connecting with their distress, 4) tolerating uncomfortable feelings aroused (e.g., fear, distress) so that we remain open to and accepting of the person suffering, and 5) acting or being motivated to act to alleviate suffering. As a prerequisite to developing a high quality compassion measure and furthering research in this field, the current study empirically investigated the factor structure of the five-element definition using a combination of existing and newly generated self-report items. This study consisted of three stages: a systematic consultation with experts to review items from existing self-report measures of compassion and generate additional items (Stage 1), exploratory factor analysis of items gathered from Stage 1 to identify the underlying structure of compassion (Stage 2), and confirmatory factor analysis to validate the identified factor structure (Stage 3). Findings showed preliminary empirical support for a five-factor structure of compassion consistent with the five-element definition. However, findings indicated that the ‘tolerating’ factor may be problematic and not a core aspect of compassion. This possibility requires further empirical testing. Limitations with items from included measures lead us to recommend against using these items collectively to assess compassion. Instead, we call for the development of a new self-report measure of compassion, using the five-element definition to guide item generation. We recommend including newly generated ‘tolerating’ items in the initial item pool, to determine whether or not factor-level issues are resolved once item-level issues are addressed

    CuBIC: cumulant based inference of higher-order correlations in massively parallel spike trains

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    Recent developments in electrophysiological and optical recording techniques enable the simultaneous observation of large numbers of neurons. A meaningful interpretation of the resulting multivariate data, however, presents a serious challenge. In particular, the estimation of higher-order correlations that characterize the cooperative dynamics of groups of neurons is impeded by the combinatorial explosion of the parameter space. The resulting requirements with respect to sample size and recording time has rendered the detection of coordinated neuronal groups exceedingly difficult. Here we describe a novel approach to infer higher-order correlations in massively parallel spike trains that is less susceptible to these problems. Based on the superimposed activity of all recorded neurons, the cumulant-based inference of higher-order correlations (CuBIC) presented here exploits the fact that the absence of higher-order correlations imposes also strong constraints on correlations of lower order. Thus, estimates of only few lower-order cumulants suffice to infer higher-order correlations in the population. As a consequence, CuBIC is much better compatible with the constraints of in vivo recordings than previous approaches, which is shown by a systematic analysis of its parameter dependence

    Network-State Modulation of Power-Law Frequency-Scaling in Visual Cortical Neurons

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    Various types of neural-based signals, such as EEG, local field potentials and intracellular synaptic potentials, integrate multiple sources of activity distributed across large assemblies. They have in common a power-law frequency-scaling structure at high frequencies, but it is still unclear whether this scaling property is dominated by intrinsic neuronal properties or by network activity. The latter case is particularly interesting because if frequency-scaling reflects the network state it could be used to characterize the functional impact of the connectivity. In intracellularly recorded neurons of cat primary visual cortex in vivo, the power spectral density of Vm activity displays a power-law structure at high frequencies with a fractional scaling exponent. We show that this exponent is not constant, but depends on the visual statistics used to drive the network. To investigate the determinants of this frequency-scaling, we considered a generic recurrent model of cortex receiving a retinotopically organized external input. Similarly to the in vivo case, our in computo simulations show that the scaling exponent reflects the correlation level imposed in the input. This systematic dependence was also replicated at the single cell level, by controlling independently, in a parametric way, the strength and the temporal decay of the pairwise correlation between presynaptic inputs. This last model was implemented in vitro by imposing the correlation control in artificial presynaptic spike trains through dynamic-clamp techniques. These in vitro manipulations induced a modulation of the scaling exponent, similar to that observed in vivo and predicted in computo. We conclude that the frequency-scaling exponent of the Vm reflects stimulus-driven correlations in the cortical network activity. Therefore, we propose that the scaling exponent could be used to read-out the “effective” connectivity responsible for the dynamical signature of the population signals measured at different integration levels, from Vm to LFP, EEG and fMRI

    Timescales of Multineuronal Activity Patterns Reflect Temporal Structure of Visual Stimuli

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    The investigation of distributed coding across multiple neurons in the cortex remains to this date a challenge. Our current understanding of collective encoding of information and the relevant timescales is still limited. Most results are restricted to disparate timescales, focused on either very fast, e.g., spike-synchrony, or slow timescales, e.g., firing rate. Here, we investigated systematically multineuronal activity patterns evolving on different timescales, spanning the whole range from spike-synchrony to mean firing rate. Using multi-electrode recordings from cat visual cortex, we show that cortical responses can be described as trajectories in a high-dimensional pattern space. Patterns evolve on a continuum of coexisting timescales that strongly relate to the temporal properties of stimuli. Timescales consistent with the time constants of neuronal membranes and fast synaptic transmission (5–20 ms) play a particularly salient role in encoding a large amount of stimulus-related information. Thus, to faithfully encode the properties of visual stimuli the brain engages multiple neurons into activity patterns evolving on multiple timescales

    Time perception and the experience of agency in meditation and hypnosis

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    Mindfulness meditation and hypnosis are related in opposing ways to awareness of intentions. The cold control theory of hypnosis proposes that hypnotic responding involves the experience of involuntariness while performing an actually intentional action. Hypnosis therefore relies upon inaccurate metacognition about intentional actions and experiences. Mindfulness meditation centrally involves awareness of intentions and is associated with improved metacognitive access to intentions. Therefore, mindfulness meditators and highly hypnotizable people may lie at opposite ends of a spectrum with regard to metacognitive access to intention‐related information. Here we review the theoretical background and evidence for differences in the metacognition of intentions in these groups, as revealed by chronometric measures of the awareness of voluntary action: the timing of an intention to move (Libet's “W” judgments) and the compressed perception of time between an intentional action and its outcome (“intentional binding”). We review these measures and critically evaluate their proposed connection to the experience of volition and sense of agency
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