4,101 research outputs found

    d_{xy}-Density wave in fermion-fermion cold atom mixtures

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    We study density wave instabilities in a doubly-degenerate Fermi-Fermi mixture with SU(2)×SU(2)SU(2)\times SU(2) symmetry on a square lattice. For sufficiently large on-site inter-species repulsion, when the two species of fermions are both at half-filling, two conventional (ss-wave) number density waves are formed with a π\pi-phase difference between them to minimize the inter-species repulsion. Upon moving one species away from half-filling, an unconventional density wave with dxyd_{xy}-wave symmetry emerges. When both species are away from the vicinity of half-filling, superconducting instabilities dominate. We present results of a functional renormalization-group calculation that maps out the phase diagram at weak couplings. Also, we provide a simple explanation for the emergence of the dxyd_{xy}-density wave phase based on a four-patch model. We find a robust and general mechanism for dxyd_{xy}-density-wave formation that is related to the shape and size of the Fermi surfaces. The density imbalance between the two species of fermions in the vicinity of half-filling leads to phase-space discrepancy for different inter-species Umklapp couplings. Using a phase space argument for leading corrections in the one-loop renormalization group approach to fermions, we show that the phase-space discrepancy in our system causes opposite flows for the two leading intra-species Umklapp couplings and that this triggers the dxyd_{xy}-density-wave instability.Comment: revised long version; 8 pages, 7 figure

    JUMPS IN DIFFERENT LEVELS OF WATER: AN OPTIMAL ENVIRONMENT TO JUMP ON LAND

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    The purpose of this study was to compare rate of force development (RFD) and rate of impact force (RIF) among on-land and in different levels of water jumps. Fourteen male participants were recruited in this study. Participants carried out the testing on land first and followed by testing in knee-high (LOW), trochanter major high (MID), and nasal-high (HIGH) of water. In each condition, participants performed 3 countermovement jumps (CMJ) separated by 15 sec rest. RFD and RIF were calculated. A repeated measure ANOVA was used for assessing the differences of variables among different conditions. The results showed that RFD for LOW is significantly lower than the others, and loading impact on-land is significantly higher than the others. Jumping in MID and HIGH are optimal levels of water for jumps training

    Implementing an institutional repository for digital archive communities: Experiences from National Taiwan University

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    This paper presents an empirical study of expanding and extending DSpace digital repository system for an academic institution. National Taiwan University created a portal web site, the Digital Archives Resource Centre (DARC), to provide the digital archives communities with preservation base for their rich research materials, and to provide the public with a helpful information retrieval service. Several modifications and extensions for the DSpace system are made in order to integrate various database resources with different formats among university departments. In this paper, we will present our empirical case in which adjustments of the DSpace system are made in areas such as data submission, metadata mapping, digital rights management, user interface and visualization. Our discussion will be focused on the useful applications in which digital archives communities benefit from the adapted DSpace system in disseminating their contents and long-term preservation within NTU campus. We will also discuss the ways in which the users benefit from the new system for searching and using digital archives

    A Web-Services-Based P2P Computing-Power Sharing Architecture

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    As demands of data processing and computing power are increasing, existing information system architectures become insufficient. Some organizations try to figure out how to keep their systems work without purchasing new hardware and software. Therefore, a Webservices-based model which shares the resource over the network like a P2P network will be proposed to meet this requirement in this paper. In addition, this paper also discusses some problems about security, motivation, flexibility, compatibility and workflow management for the traditional P2P power sharing models. Our new computing architecture - Computing Power Services (CPS) - will aim to address these problems. For the shortcomings about flexibility, compatibility and workflow management, CPS utilizes Web Services and Business Process Execution Language (BPEL) to overcome them. Because CPS is assumed to run in a reliable network where peers trust each other, the concerns about security and motivation will be negated. In essence, CPS is a lightweight Web-Services-based P2P power sharing environment and suitable for executing computing works in batch in a reliable networ

    Novel microinjector for carrying bone substitutes for bone regeneration in periodontal diseases

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    Background/PurposeTraditionally, guide bone regeneration (GBR) was a widely used method for repairing bone lost from periodontal disease. There were some disadvantages associated with the GBR method, such as the need for a stable barrier membrane and a new creative cavity during the surgical process. To address these disadvantages, the purpose of this study was to evaluate a novel microinjector developed for dental applications. The microinjector was designed to carry bone graft substitutes to restore bone defects for bone regeneration in periodontal diseases. The device would be used to replace the GBR method.MethodsIn this study, the injected force and ejected volume of substitutes (including air, water, and ethanol) were defined by Hooke's law (n = 3). The optimal particle size of bone graft substitutes was determined by measuring the recycle ratio of bone graft substitutes from the microinjector (n = 3). Furthermore, a novel agarose gel model was used to evaluate the feasibility of the microinjector.ResultsThe current study found that the injected force was less than 0.4 N for obtaining the ejected volume of approximately 2 mL, and when the particle size of tricalcium phosphate (TCP) was smaller than 0.5 mm, 80% TCP could be ejected from the microinjector. Furthermore, by using an agarose model to simulate the periodontal soft tissue, it was also found that bone graft substitutes could be easily injected into the gel.ConclusionThe results confirmed the feasibility of this novel microinjector for dental applications to carry bone graft substitutes for the restoration of bone defects of periodontal disease

    The influences of cognition of institutional logics and triple helix relations on innovation performance: An empirical study of firms in industrial park in Taiwan

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    Abstract. The present study set out to investigate into the influences of cognition of institutional logics and triple helix relationships (i.e., the industry-university-government linkages) on firm innovation performance in the context of Taiwan industrial parks. The data from 131 organizational-level questionnaires collected from firms located in different industrial parks were analyzed. The results showed that cognition of institutional logics is positively associated with firms’ innovation performance. Furthermore, such positive relationship is strengthened by the number of triple helix relationships in the form of mediation but not moderation effect. Theoretical and practical implications were elaborated. Keywords. Cognition of institutional logics, Triple helix, Innovation performance, Industrial park.JEL. M10, M14

    The influences of perceived organizational slacks on firms’ satisfaction in industrial park service: Moderation effect of park attributes and administrative supports

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    Abstract. This study examines the effect of perceived organizational slack on firms’ satisfaction in services offered by industrial park. Survey questionnaires were collected from 131 firms located in various industrial parks in Taiwan. Results supports that, first, perceived organizational slack is negatively related to firms’ satisfaction in industrial park’s services. Moreover, the strengths of such negative relationships were differentiated due to the moderation effect of different park attributes and administrative supports. Policy and theoretical implications were discussed.Keywords. Perceived organizational slacks, Service satisfaction, Park attributes and administrative supports.JEL. M10, M11, M14
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