2,307 research outputs found

    Ultracold polarized Fermi gas at intermediate temperatures

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    We consider non-zero temperature properties of the polarized two-component Fermi gas. We point out that stable polarized paired states which are more stable than their phase separated counterparts with unpolarized superfluid region can exist below the critical temperature. We also solve the system behavior in a trap using the local density approximation and find gradually increasing polarization in the center of the system as the temperature is increased. However, in the strongly interacting region the central polarization increases most rapidly close to the mean-field critical temperature, which is known to be substantially higher than the critical temperature for superfluidity. This indicates that most of the phase separation occurs in the fluctuation region prior to superfluidity and that the polarization in the actual superfluid is modest.Comment: Final published versio

    Long term ordering kinetics of the two dimensional q-state Potts model

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    We studied the non-equilibrium dynamics of the q-state Potts model in the square lattice, after a quench to sub-critical temperatures. By means of a continuous time Monte Carlo algorithm (non-conserved order parameter dynamics) we analyzed the long term behavior of the energy and relaxation time for a wide range of quench temperatures and system sizes. For q>4 we found the existence of different dynamical regimes, according to quench temperature range. At low (but finite) temperatures and very long times the Lifshitz-Allen-Cahn domain growth behavior is interrupted with finite probability when the system stuck in highly symmetric non-equilibrium metastable states, which induce activation in the domain growth, in agreement with early predictions of Lifshitz [JETP 42, 1354 (1962)]. Moreover, if the temperature is very low, the system always gets stuck at short times in a highly disordered metastable states with finite life time, which have been recently identified as glassy states. The finite size scaling properties of the different relaxation times involved, as well as their temperature dependency are analyzed in detail.Comment: 10 pages, 17 figure

    A virtual collaborative platform to support building information modeling implementation for energy efficiency

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    There is increased interest in complying with the new regulations and policies associated with the climate change. In particular industries such as the AEC (Architecture, Engineering and Construction) industry seek to find new strategies and practices for facilitating sustainability but also new regulations to improve efficiency at the building level. Institutions and industrial bodies are now in the process of alignment with new legislative stipulations regarding carbon emissions with wider reflection into environment, social and economic models. At building level such strategies refer to decarbonisation and energy efficiency supported with data driven techniques enriched with virtual collaboration and optimization methods. The increased interest of the research community in Building Information Modeling (BIM) has facilitated numerous solutions ranging from digital products, information retrieval, and optimization techniques all aiming at addressing energy optimization and performance gap reduction. In this paper we present how a virtual collaborative system can be efficiently used for implementing BIM based energy optimization for controlling, monitoring buildings and running energy optimization, greatly contributing to creating a BIM construction community with energy practices. The solution described, known as energy-bim.com platform, disseminates energy efficient practices and community engagement and provides support for building managers in implementing energy efficient optimization plans

    Somatostatin agonist pasireotide inhibits exercise stimulated growth in the male Siberian hamster (Phodopus sungorus)

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    R.Dumbell was supported by a University of Aberdeen PhD studentship and a research visit grant awarded by the British Society of Neuroendocrinology. Further support was provided by the Scottish Government Rural and Environment Science and Analytical Services Division (Barrett and the German Research Foundation (DFG; STE 331/8-1; Steinlechner lab). We are grateful for technical assistance from Dana Wilson at RINH and Siegried Hiliken at UVMH, and thank Dr Claus-Dieter Mayer of Biomathematics & Statistics Scotland for valuable advice on statistical analysis.Peer reviewedPostprin

    Glassy behaviour in short range lattice models without quenched disorder

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    We investigate the quenching process in lattice systems with short range interaction and several crystalline states as ground states. We consider in particular the following systems on square lattice: - hard particle (exclusion) model; - q states planar Potts model. The system is initially in a homogeneous disordered phase and relaxes toward a new equilibrium state as soon as the temperature is rapidly lowered. The time evolution can be described numerically by a stochastic process such as the Metropolis algorithm. The number of pure, equivalent, ground states is q for the Potts model and r for the hard particle model, and it is known that for r or q larger or equal to d+1, the final equilibrium state may be polycrystalline, i.e. not made of a uniform phase. We find that in addition n_g and q_g exist such that for r > r_g, or q > q_g the system evolves toward a glassy state, i.e. a state in which the ratio of the interaction energy among the different crystalline phases to the total energy of the system never vanishes; moreover we find indications that r_g=q_g. We infer that q=q_g (and r=r_g) corresponds to the crossing from second order to discontinuous transition in the phase diagram of the system.Comment: 10 pages, 3 figure

    Exponential torsion growth for random 3-manifolds

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    We show that a random 3-manifold with positive first Betti number admits a tower of cyclic covers with exponential torsion growth

    Circadian Organization in Hemimetabolous Insects

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    The circadian system of hemimetabolous insects is reviewed in respect to the locus of the circadian clock and multioscillatory organization. Because of relatively easy access to the nervous system, the neuronal organization of the clock system in hemimetabolous insects has been studied, yielding identification of the compound eye as the major photoreceptor for entrainment and the optic lobe for the circadian clock locus. The clock site within the optic lobe is inconsistent among reported species; in cockroaches the lobula was previously thought to be a most likely clock locus but accessory medulla is recently stressed to be a clock center, while more distal part of the optic lobe including the lamina and the outer medulla area for the cricket. Identification of the clock cells needs further critical studies. Although each optic lobe clock seems functionally identical, in respect to photic entrainment and generation of the rhythm, the bilaterally paired clocks form a functional unit. They interact to produce a stable time structure within individual insects by exchanging photic and temporal information through neural pathways, in which serotonin and pigment-dispersing factor (PDF) are involved as chemical messengers. The mutual interaction also plays an important role in seasonal adaptation of the rhythm

    Internet-Enabled Co-Production: Partnering or Competing with Customers?

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    The Internet is democratizing commerce by turning economic models that were based on a strict separation between providers and consumers into models where this distinction is increasingly blurred. This implies significant opportunities and challenges for organizations, particularly with respect to the role that their customers play in the generation of economic value. Are customers partners or competitors? While firms typically strive to implement business models that leverage the customers as a resource (i.e., customer co-production), models in which customers are competitors (i.e., peer production) are frequently met with attempts to co-opt these customers (i.e., hybrid co-production). The purpose of this panel, presented at the 2006 International Conference on Information Systems, is to explore the range of Internet-enabled co-production models (i.e., customer and hybrid co-production) and the opportunities and challenges that they present for firms

    Open Repair Versus Thoracic Endovascular Aortic Repair in Multiple-Injured Patients: Observations From a Level-1 Trauma Center

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    Background: Blunt trauma of the thoracic aorta is a rare but potentially life-threatening entity. Intimal tears are a domain of non-operative management, whereas all other types of lesions should be repaired urgently. There is now a clear trend favoring minimally invasive stent grafting over open surgical repair. Objectives: The aim of the present study was to retrospectively evaluate the mortality and morbidity with either treatment option. Therefore, a retrospective observational study was performed to compare two different treatment methods at two different time periods at one trauma center. Patients and Methods: Between 1977 and 2012, all severely injured patients referred to our level 1 trauma center were screened for blunt aortic injuries. We compared baseline characteristics, 30-day and overall mortality, morbidity, duration of intensive care treatment, procedure time, and transfusion of packed red blood between patients who underwent open surgical or stent repair. Results: During the observation period, 45 blunt aortic injuries were recorded. The average Injury Severity Score (ISS) was 41.8 (range 29 - 68). Twenty-five patients underwent Open Repair (OR), and another 20 patients were scheduled to emergency stent grafting. The 30-day mortality in the surgical and stent groups were 5/25 (20%) and 2/20 (10%), respectively. The average time for open surgery was 151 minutes; the mean time for stent grafting was 67 minutes (P = 0.001). Postoperative stay on the intensive care unit was between one and 59 days (median 10) in group one and between four and 50 days in group two (median 26)(P = 0.03). Patients undergoing OR required transfusion of 6.0 units of packed red cells in median; patients undergoing stent grafting required a median of 2.0 units of packed red cells (P < 0.001). In the stent grafting group, 30-day mortality was 10% (2/20). Conclusions: Due to more sophisticated diagnostic tools and surgical approaches, mortality and morbidity of blunt aortic injuries were significantly reduced over the years compared to thoracic endovascular aortic repair and OR over two different time periods

    The Trans-Pacific Partnership Agreement: Looking Ahead to the Next Steps

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    Pressure has been building for the conclusion of the 12-country Trans-Pacific Partnership (TPP) negotiations. Getting the deal done is important, but the TPP is not just another free trade agreement (FTA). It represents the chance to set a trade agenda for the future across a wide range of topics for countries throughout the Asia-Pacific region. This means that the agreement should not be settled in haste. More importantly, it also means that key decisions need to be reached about broader issues related to the institutional structure of the TPP. These decisions must be made now, before the deal is closed, on issues such as how to create the TPP as a living agreement, the formation of a TPP Secretariat, and the clarification of entry conditions for future members such as the People’s Republic of China (PRC). These choices must be made deliberately and carefully even while officials are struggling with reaching closure on the most highly sensitive issues still remaining in the agreement. It will not be easy, but wise decisions are necessary now to ensure the long-term success of the TPP
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