2,661 research outputs found
On the finding of the Indo-Pacific fish Scomberomorus commerson in Rhodes (Greece)
The occurrence of the Indo-Pacific fish Scomberomorus commerson was observed for the first time in the Hellenic waters of the SE Aegean Sea during the spring 2008. The record may represent a first indication of a population expansion of this alien species along the southern coasts of the Aegean Sea
Gonioinfradens paucidentatus (A. Milne Edwards, 1861) (Crustacea, Decapoda, Portunidae): a new alien crab in the Mediterranean Sea
The first record for the Mediterranean Sea of the Red Sea/Indo-Pacific portunid Gonioinfradens paucidentatus (red swimming crab) is documented. A detailed description of the specimens collected at Rodos Island (southeastern Aegean Sea) is given, while possible introduction vectors of the species in the area are discussed
Conservation of information and the foundations of quantum mechanics
We review a recent approach to the foundations of quantum mechanics inspired
by quantum information theory. The approach is based on a general framework,
which allows one to address a large class of physical theories which share
basic information-theoretic features. We first illustrate two very primitive
features, expressed by the axioms of causality and purity-preservation, which
are satisfied by both classical and quantum theory. We then discuss the axiom
of purification, which expresses a strong version of the Conservation of
Information and captures the core of a vast number of protocols in quantum
information. Purification is a highly non-classical feature and leads directly
to the emergence of entanglement at the purely conceptual level, without any
reference to the superposition principle. Supplemented by a few additional
requirements, satisfied by classical and quantum theory, it provides a complete
axiomatic characterization of quantum theory for finite dimensional systems.Comment: 11 pages, contribution to the Proceedings of the 3rd International
Conference on New Frontiers in Physics, July 28-August 6 2014, Orthodox
Academy of Crete, Kolymbari, Cret
Modelling and experimental validation of a fluidized bed reactor freeboard region: application to natural gas combustion
A theoretical and experimental study of natural gas-air mixture combustion in a fluidized bed of sand particles is presented. The operating temperatures are lower than a critical temperature of 800 °C above which the combustion occurs in the vicinity of the fluidized bed. Our study focusses on the freeboard zone where most of the methane combustion takes place at such temperatures. Experimental results show the essential role of the projection zone in determining the global thermal efficiency of the reactor. The dense bed temperature, the fluidizing velocity and the mean particle diameter significantly affect the thermal behaviours. A model for natural gas-air mixture combustion in fluidized beds is proposed, counting for interactions between dense and dilute regions of the reactor [Pré et al. (1998)] supplemented with the freeboard region modelling of Kunii-Levenspiel (1990). Thermal exchanges due to the convection between gas and particles, and due to the conduction and radiation phenomena between the gas-particle suspension and the reactor walls are counted. The kinetic scheme for the methane conversion is that proposed by Dryer and Glassman (1973). Model predictions are in good agreement with the measurements
Probabilistic Feasibility for Nonlinear Systems with Non-Gaussian Uncertainty using RRT
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
Avenues of cognition of nongravitational local gauge field theories
This controbution is devoted to present basic fearures of a unifying local gauge field theory, prevailing up to a mass scale of approximately 10 16 GeV , allowing the neglect of gravitational curvature effects – indicated by the attribute : ’nongravitational’ in the title above
Azimuthal angular correlations of D mesons with charged particles in pp collisions at √s = 7 TeV and p-Pb collisions at √s = 7 TeV and p-Pb collisions at √S NN
Performance Studies of Micromegas Chambers for the New Small Wheel Upgrade Project
Micromegas, an abbreviation for Micro MEsh Gaseous Structure (MM), is a robust detector with excellent spatial resolution and high rate capability. An activity, called Muon ATLAS MicroMegas Activity (MAMMA), was initiated in 2007 in order to explore the potential of the MM technology for use in the ATLAS experiment. After several years of prototyping and testing, the ATLAS collaboration has chosen the MM technology along with the small-strip Thin Gap Chambers (sTGC) for the upgrade of the inner muon station in the high-rapidity region, the so called New Small Wheel (NSW) upgrade project. It will employ eight layers of MM and eight layers of sTGC detectors per wheel. The NSW project requires fully efficient MM chambers, able to cope with the maximum expected rate of featuring single plane spatial resolution better than . The MM detectors will cover a total active area of and will be operated in a moderate magnetic field with intensity up to . Moreover, together with the precise tracking capability the NSW MM chambers will contribute to the ATLAS Level-1 trigger system. An extensive program is ongoing to determine the best configuration that satisfies these requirements. Several tests have been performed on small () and medium () size prototypes using medium () and high momentum () hadron beams at CERN. A brief overview of the results obtained from recent performance tests concerning the aspects discussed above is presented
Understanding lived experiences and perceptions of resilience in black and South Asian Muslim children living in East London: a qualitative study protocol.
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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