349 research outputs found

    Density profiles and collective excitations of a trapped two component Fermi vapour

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    We discuss the ground state and the small-amplitude excitations of a degenerate vapour of fermionic atoms placed in two hyperfine states inside a spherical harmonic trap. An equations-of-motion approach is set up to discuss the hydrodynamic dissipation processes from the interactions between the two components of the fluid beyond mean-field theory and to emphasize analogies with spin dynamics and spin diffusion in a homogeneous Fermi liquid. The conditions for the establishment of a collisional regime via scattering against cold-atom impurities are analyzed. The equilibrium density profiles are then calculated for a two-component vapour of 40K atoms: they are little modified by the interactions for presently relevant values of the system parameters, but spatial separation of the two components will spontaneously arise as the number of atoms in the trap is increased. The eigenmodes of collective oscillation in both the total particle number density and the concentration density are evaluated analytically in the special case of a symmetric two-component vapour in the collisional regime. The dispersion relation of the surface modes for the total particle density reduces in this case to that of a one-component Fermi vapour, whereas the frequencies of all other modes are shifted by the interactions.Comment: 14 pages, 4 figure

    Particulate matter and airborne fungi concentrations in schools in Athens

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    Indoor Air Quality degradation is of exceptional concern due to the potential adverse effects indoor air pollutants have on human’s health. Students are a susceptible group of people, who spend a lot of their time within classrooms. The purpose of this study is to investigate the concentration levels of particulate matter (PM) and total airborne fungi, in school classrooms. Further objective is to examine possible correlations between PM10, PM2.5, PM1, ultrafine particles (UFPs, diameter<100 nm), and airborne fungi. The measurements were performed using fully automated instrumentation. The results indicate that a lot of PM10 concentrations exceeded the proposed daily limit of 50μg/m3. Also, in some cases the concentration of the total airborne fungi indoors, exceeded their concentration outdoors. There is evidence that certain correlations exist between PM and airborne fungi

    Failure of ultrasound to diagnose a giant ovarian cyst: a case report

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    Ultrasonography is the method of choice in the diagnosis of ovarian cysts. In this case report, a cyst of enormous volume (>35 litres) was limiting the application of ultrasound techniques giving the false impression of ascites. A 55-year-old woman was finally diagnosed as having a giant ovarian mucosal-serosal cystadenoma of borderline potential after undergoing a total abdominal hysterectomy with salpingo-oophorectomy and excision of the cyst. In the literature, similar conditions have been described with the term ‘empty abdomen’

    Spirulina in Clinical Practice: Evidence-Based Human Applications

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    Spirulina or Arthrospira is a blue-green alga that became famous after it was successfully used by NASA as a dietary supplement for astronauts on space missions. It has the ability to modulate immune functions and exhibits anti-inflammatory properties by inhibiting the release of histamine by mast cells. Multiple studies investigating the efficacy and the potential clinical applications of Spirulina in treating several diseases have been performed and a few randomized controlled trials and systematic reviews suggest that this alga may improve several symptoms and may even have an anticancer, antiviral and antiallergic effects. Current and potential clinical applications, issues of safety, indications, side-effects and levels of evidence are addressed in this review. Areas of ongoing and future research are also discussed

    Embryo with XYY syndrome presenting with clubfoot: a case report

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    Talipes equinovarus (clubfoot) is a skeletal anomaly of the embryo’s legs, with a frequency of 1-3:1000 living born babies. It may occur as an independent anomaly, or as part of a syndrome with concomitant chromosomal abnormalities

    Multi-disciplinary analysis of light shelves application within a student dormitory refurbishment

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    The achievement of sustainable cities and communities is closely linked to an accurate design of the buildings. In this context, the transparent elements of the building envelope have a crucial role since, on one hand, they are a bottleneck in regards to heat and mass transfers and sound propagation, while, on the other hand, they must allow daylight penetration. Thus, they are responsible for occupants' thermal and visual comfort and their health. Considering passive solutions for windows, the light shelves can improve natural light penetration, reducing the lights' electricity demand and controlling windows' related thermal aspects. The scientific literature is characterized by several studies that analyze this topic, which, however, focus only on the daylight field and sometimes the energy saving for lights. Moreover, they often refer to fixed sky type for the simulations. The aim of the present study is to analyze the application of the light shelves with a multi-disciplinary approach, by means of dynamic simulations, in the EnergyPlus engine, for a whole year. A new methodological approach is presented in order to investigate the technology under different fields of interest: daylight, lighting energy, cooling and heating needs, and thermo-hygrometric comfort. The case study chosen is an existing building, a student dormitory belonging to the University of Athens. It is subject to a deep energy renovation to conform to the "nearly Zero Energy Building" target, in the frame of a European research project called Pro-GET-onE (G.A No. 723747). By means of the calibrated numerical model of this HVAC-building system, ten different configurations of light shelves have been investigated. The best solution is given by the application of an internal horizontal light shelf placed at 50 cm from the top of the window with a depth of 90 or 60 cm. It has been found that despite the reduction in electricity demand for lighting, the variation in heating and cooling needs does not always lead to a benefit

    Application of light shelves in a refurbished student dormitory: Energy, lightings and comfort aspects

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    The transparent elements of the building envelope have a crucial role not only in term of heat and mass transfers control, but also for natural light penetration, sound insulation, thermal and visual comfort of the occupants and their health. Among passive technologies, the light shelves could be architectural solutions for improving daylight penetration and for controlling thermal loads. The available research papers usually focus on one aspect. For this reason, the aim of the present study is to analyse the application of the light shelves with multidisciplinary approach and thus, taking into account: daylight, electricity for lighting, cooling and heating needs and thermo-hygrometric comfort. The case study is a real dormitory building placed in Athens and subject to a deep energy renovation toward the nearly zero energy building target. EnergyPlus, by means of DesignBuilder interface, has been used as dynamic simulation tool. Among ten different configurations, the optimal one turns out to be the internal horizontal light shelf placed at 50 cm from the top of the window with a depth of 90 cm or 60 cm. It has been found that in some cases the reduction of electricity for lighting cannot balance the variation in heating and cooling needs

    Designing normative open virtual enterprises

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    This is an Accepted Manuscript of an article published by Taylor & Francis Group in Enterprise Information Systems on 23/03/2016, available online: http://www.tandfonline.com/10.1080/17517575.2015.1036927.[EN] There is an increasing interest on developing virtual enterprises in order to deal with the globalisation of the economy, the rapid growth of information technologies and the increase of competitiveness. In this paper we deal with the development of normative open virtual enterprises (NOVEs). They are systems with a global objective that are composed of a set of heterogeneous entities and enterprises that exchange services following a specific normative context. In order to analyse and design systems of this kind the multi-agent paradigm seems suitable because it offers a specific solution for supporting the social and contractual relationships between enterprises and for formalising their business processes. This paper presents how the Regulated Open Multiagent systems (ROMAS) methodology, an agent-oriented software methodology, can be used to analyse and design NOVEs. ROMAS offers a complete development process that allows identifying and formalising of the structure of NOVEs, their normative context and the interactions among their members. The use of ROMAS is exemplified by means of a case study that represents an automotive supply chain.This work was partially supported by the projects [PROMETEOII/2013/019], [TIN2012-36586-C03-01], [FP7-29493], [TIN2011-27652-C03-00] and [CSD2007-00022], and the CASES project within the 7th European Community Framework Programme [grant agreement number 294931].Garcia Marques, ME.; Giret Boggino, AS.; Botti Navarro, VJ. (2016). Designing normative open virtual enterprises. Enterprise Information Systems. 10(3):303-324. https://doi.org/10.1080/17517575.2015.1036927S303324103Cardoso, H. L., Urbano, J., Brandão, P., Rocha, A. P., & Oliveira, E. (2012). 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