3,495 research outputs found

    Are the energy and virial routes to thermodynamics equivalent for hard spheres?

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    The internal energy of hard spheres (HS) is the same as that of an ideal gas, so that the energy route to thermodynamics becomes useless. This problem can be avoided by taking an interaction potential that reduces to the HS one in certain limits. In this paper the square-shoulder (SS) potential characterized by a hard-core diameter σ\sigma', a soft-core diameter σ>σ\sigma>\sigma' and a shoulder height ϵ\epsilon is considered. The SS potential becomes the HS one if (i) ϵ0\epsilon\to 0, or (ii) ϵ\epsilon\to\infty, or (iii) σσ\sigma'\to\sigma or (iv) σ0\sigma'\to 0 and ϵ\epsilon\to\infty. The energy-route equation of state for the HS fluid is obtained in terms of the radial distribution function for the SS fluid by taking the limits (i) and (ii). This equation of state is shown to exhibit, in general, an artificial dependence on the diameter ratio σ/σ\sigma'/\sigma. If furthermore the limit σ/σ1\sigma'/\sigma\to 1 is taken, the resulting equation of state for HS coincides with that obtained through the virial route. The necessary and sufficient condition to get thermodynamic consistency between both routes for arbitrary σ/σ\sigma'/\sigma is derived.Comment: 10 pages, 4 figures; v2: minor changes; to be published in the special issue of Molecular Physics dedicated to the Seventh Liblice Conference on the Statistical Mechanics of Liquids (Lednice, Czech Republic, June 11-16, 2006

    Managing expert knowledge in water network expansion project implementation

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    The implementation of expansion projects of water networks supplying growing cities is deemed to be a complex decision-making problem involving both technical aspects and expert knowledge. Management and control processes must rely on experts in the field whose knowhow must be coupled with techniques able to deal with the natural subjectivity that affects input evaluations. Given the presence of many decision-making elements, the choice of proper hydraulic technical parameters may be linked to the main aspects of analysis requiring formal expert evaluation. In this contribution, the simulation of hydraulic indicators is integrated with a multi-criteria approach able to eventually determine those areas of a water network through which organising the expansion may be more beneficial. The software EPAnet 2.0 is first used for hydraulic simulations, whereas the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) will eventually rank network's nodes. A case study is solved to demonstrate the applicability and effectiveness of the proposed approach. Copyright (C) 2021 The Authors

    A hybrid intelligent agent for notification of users distracted by mobile phones in an urban environment

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    Mobile devices are now ubiquitous in daily life and the number of activities that can be performed using them is continually growing. This implies increased attention being placed on the device and diverted away from events taking place in the surrounding environment. The impact of using a smartphone on pedestrians in the vicinity of urban traffic has been investigated in a multimodal, fully immersive, virtual reality environment. Based on experimental data collected, an agent to improve the attention of users in such situations has been developed. The proposed agent uses explicit, contextual data from experimental conditions to feed a statistical learning model. The agent’s decision process is aimed at notifying users when they become unaware of critical events in their surroundings

    Evaluating estuarine nursery use and life history patterns of Pomatomus saltatrix in eastern Australia

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    Estuaries provide important nursery habitats for juvenile fish, but many species move between estuarine and coastal habitats throughout their life. We used otolith chemistry to evaluate the use of estuaries and the coastal marine environment by juvenile Pomatomus saltatrix in eastern Australia. Otolith chemical signatures of juveniles from 12 estuaries, spanning 10° of latitude, were characterised using laser ablation-inductively coupled plasma-mass spectrometry. Based upon multivariate otolith elemental signatures, fish collected from most estuaries could not be successfully discriminated from one another. This was attributed to the varying influence of marine water on otolith elemental composition in fish from all estuaries. Using a reduced number of estuarine groups, the multivariate juvenile otolith elemental signatures and univariate Sr:Ca ratio suggest that between 24 and 52% of adult P. saltatrix had a juvenile period influenced by the marine environment. Elemental profiles across adult (age-1) otoliths highlighted a variety of life history patterns, not all consistent with a juvenile estuarine phase. Furthermore, the presence of age-0 juveniles in coastal waters was confirmed from historical length-frequency data from coastal trawls. Combining multiple lines of evidence suggests considerable plasticity in juvenile life history for P. saltatrix in eastern Australia through their utilisation of both estuarine and coastal nurseries. Knowledge of juvenile life history is important for the management of coastal species of commercial and recreational importance such as P. saltatrix.info:eu-repo/semantics/publishedVersio

    Detection of multipartite entanglement with two-body correlations

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    We show how to detect entanglement with criteria built from simple two-body correlation terms. Since many natural Hamiltonians are sums of such correlation terms, our ideas can be used to detect entanglement by energy measurement. Our criteria can straightforwardly be applied for detecting different forms of multipartite entanglement in familiar spin models in thermal equilibrium.Comment: 5 pages including 2 figures, LaTeX; for the proceedings of the DPG spring meeting, Berlin, March 200

    Sweet's syndrome associated with cellulitis - a challenging diagnosis

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    Sweet's syndrome is a neutrophilic dermatosis with worldwide distribution that has been associated with inflammatory autoimmune diseases, infections, malignancies, drugs, and pregnancy. The disease is idiopathic in up to 50% of patients. A 64-year-old woman, diagnosed with right limb cellulitis (4 days of evolution), was seen at our department, due to persistent cellulitis and progressive appearance of painful nodules and plaques in both shins and the right forearm (2 days of evolution). Taken together, clinical, laboratory and pathological data suggested the diagnosis of Sweet's syndrome, probably secondary to cellulitis of the right inferior limb. We suggest that cellulitis may be associated with Sweet's syndrome, a rare association in the literature

    Five-year review of an international clinical research-training program

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    The exponential increase in clinical research has profoundly changed medical sciences. Evidence that has accumulated in the past three decades from clinical trials has led to the proposal that clinical care should not be based solely on clinical expertise and patient values, and should integrate robust data from systematic research. As a consequence, clinical research has become more complex and methods have become more rigorous, and evidence is usually not easily translated into clinical practice. Therefore, the instruction of clinical research methods for scientists and clinicians must adapt to this new reality. To address this challenge, a global distance-learning clinical research-training program was developed, based on collaborative learning, the pedagogical goal of which was to develop critical thinking skills in clinical research. We describe and analyze the challenges and possible solutions of this course after 5 years of experience (2008-2012) with this program. Through evaluation by students and faculty, we identified and reviewed the following challenges of our program: 1) student engagement and motivation, 2) impact of heterogeneous audience on learning, 3) learning in large groups, 4) enhancing group learning, 5) enhancing social presence, 6) dropouts, 7) quality control, and 8) course management. We discuss these issues and potential alternatives with regard to our research and background
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