2,420 research outputs found

    An Inconsistency in the Simulation of Bose-Einstein Correlations

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    We show that the formalism commonly used to implement Bose-Einstein correlations in Monte-Carlo simulations can lead to values of the two-particle correlator significantly smaller than unity, in the case of sources with strong position-momentum correlations. This is more pronounced when the phase space of the emitted particles is strongly reduced by experimental acceptance or kinematic analysis selections. It is inconsistent with general principles according to which the Bose-Einstein correlator is larger than unity. This inconsistency seems to be rooted in the fact that quantum mechanical localization properties are not taken into account properly.Comment: 10 pages, LaTe

    Evaluation of the Beam Background Contribution to the pp Minimum Bias Sample Used for First Physics

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    The note describes the beam background conditions during first physics data taking with ALICE and the strategy for the evaluation of the LHC beam background contribution to the minimum bias event sample used for first physics

    Update of marine alien species in Hellenic waters

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    The list of marine alien species in Hellenic waters is updated taking into account new findings (published and unpublished data). According to the present work, the number of these species has increased from 90 (known until end 2003) to 128. Most of them are zoobenthic species followed by fish and macroalgae. An interannual analysis revealed an important increase of alien species during the last years. The study of their geographic distribution showed that their majority is present in the southeastern Aegean. More than 55% of them are well established, while about 40% are casual records. Their main pathway of introduction seems to be the Suez Canal followed by shipping, whereas the Straits of Gibraltar, aquaculture and the Straits of Dardanelles appear to play a less important role in their invasion of Hellenic waters. These findings are discussed considering environmental and anthropogenic factors

    Thirty years after - dramatic change in the coastal marine habitats of Kos Island (Greece), 1981-2013.

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    Results of recent fieldwork were compared with data collected in 1981, taken as a reference condition. Surveys were conducted with the same method (time-based visual census along random paths), in the same sites, by the same people. Semi-quantitative inventories of conspicuous species were analysed by univariate and multivariate techniques. Available information on the main potential stressors indicated that a regime shift has occurred in these 30+ years: sea surface temperature rose by1-2°C, human pressure grew impressively, and invasion by several alien species took place. Consistently, a phase shift occurred in the biological communities. Of the 120 conspicuous species found in total, only 51 were common to both surveys; 31 species ('losses') were found in 1981 but not again in 2013, 38 ('gains') were found exclusively in 2013, 16 ('winners') increased their abundance, 8 ('losers') got scarcer, and 27 underwent little or no change. Gains included 7 alien, 2 nitrophilic, and 7 thermophilic species. Multivariate analysis evidenced biotic homogenisation in 2013 and huge change in rocky reef habitats. The once flourishing algal forests have disappeared to leave space to sponges and wide areas of bare substratum. This has most probably been the result of overgrazing by alien herbivorous fishes (Siganus luridus and S. rivulatus), whose establishment and spread has been favoured by seawater warming; the synergic action of local human impacts was also evidenced

    A critical role for the Sp1-binding sites in the transforming growth factor-β-mediated inhibition of lipoprotein lipase gene expression in macrophages

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    Increasing evidence suggests that the cytokine transforming growth factor-β (TGF-β) inhibits the development of atherosclerosis. The lipoprotein lipase (LPL) enzyme expressed by macrophages has been implicated in the pathogenesis of atherosclerosis by stimulating the uptake of lipoprotein particles. Unfortunately, the action of TGF-β on the expression of LPL in macrophages remains largely unclear. We show that TGF-β inhibits LPL gene expression at the transcriptional level. Transient transfection assays reveal that the −31/+187 sequence contains the minimal TGF-β-responsive elements. Electrophoretic mobility shift assays show that Sp1 and Sp3 interact with two regions in the −31/+187 sequence. Mutations of these Sp1/Sp3 sites abolish the TGF-β-mediated suppression whereas multimers of the sequence impart the response to a heterologous promoter. TGF-β has no effect on the binding or steady-state polypeptide levels of Sp1 and Sp3. These results, therefore, suggest a novel mechanism for the TGF-β-mediated repression of LPL gene transcription that involves regulation of the action of Sp1 and Sp3

    The first confirmed record of the Atlantic blue crab Callinectes sapidus Rathbun, 1896 (Decapoda, Brachyura) from Maltese waters

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    The invasive portunid species Callinectes sapidus is hereby recorded for the first time from Maltese waters, thus updating the known distribution of this decapod of Atlantic origin within the Mediterranean. Potential introduction pathways of the species to Maltese waters are discussed

    Probabilistic Feasibility for Nonlinear Systems with Non-Gaussian Uncertainty using RRT

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    For motion planning problems involving many or unbounded forms of uncertainty, it may not be possible to identify a path guaranteed to be feasible, requiring consideration of the trade-o between planner conservatism and the risk of infeasibility. Recent work developed the chance constrained rapidly-exploring random tree (CC-RRT) algorithm, a real-time planning algorithm which can e ciently compute risk at each timestep in order to guarantee probabilistic feasibility. However, the results in that paper require the dual assumptions of a linear system and Gaussian uncertainty, two assumptions which are often not applicable to many real-life path planning scenarios. This paper presents several extensions to the CC-RRT framework which allow these assumptions to be relaxed. For nonlinear systems subject to Gaussian process noise, state distributions can be approximated as Gaussian by considering a linearization of the dynamics at each timestep; simulation results demonstrate the e ective of this approach for both open-loop and closed-loop dynamics. For systems subject to non-Gaussian uncertainty, we propose a particle-based representation of the uncertainty, and thus the state distributions; as the number of particles increases, the particles approach the true uncertainty. A key aspect of this approach relative to previous work is the consideration of probabilistic bounds on constraint satisfaction, both at every timestep and over the duration of entire paths.United States. Air Force (USAF, grant FA9550-08-1-0086)United States. Air Force Office of Scientific Research (AFOSR, Grant FA9550-08-1-0086

    Understanding lived experiences and perceptions of resilience in black and South Asian Muslim children living in East London: a qualitative study protocol.

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    INTRODUCTION: It is important to promote resilience in preadolescence; however, there is limited research on children's understandings and experiences of resilience. Quantitative approaches may not capture dynamic and context-specific aspects of resilience. Resilience research has historically focused on white, middle-class Western adults and adolescents, creating an evidence gap regarding diverse experiences of resilience in middle childhood which could inform interventions. East London's Muslim community represents a diverse, growing population. Despite being disproportionately affected by deprivation and racial and cultural discrimination, this population is under-represented in resilience research. Using participatory and arts-based methods, this study aims to explore lived experiences and perceptions of resilience in black and South Asian Muslim children living in East London. METHODS AND ANALYSIS: We propose a qualitative study, grounded in embodied inquiry, consisting of a participatory workshop with 6-12 children and their parents/carers to explore lived experiences and perceptions of resilience. Participants will be identified and recruited from community settings in East London. Eligible participants will be English-speaking Muslims who identify as being black or South Asian, have a child aged 8-12 years and live in East London. The workshop (approx. 3.5 hours) will take place at an Islamic community centre and will include body mapping with children and a focus group discussion with parents/carers to explore resilience perspectives and meanings. Participants will also complete a demographic survey. Workshop audio recordings will be transcribed verbatim and body maps and other paper-based activities will be photographed. Data will be analysed using systematic visuo-textual analysis which affords equal importance to visual and textual data. ETHICS AND DISSEMINATION: The Queen Mary Ethics of Research Committee at Queen Mary University of London has approved this study (approval date: 9 October 2023; ref: QME23.0042). The researchers plan to publish the results in peer-reviewed journals and present findings at academic conferences
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