16,080 research outputs found

    Fluid Dynamical Description of the Chiral Transition

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    We investigate the dynamics of the chiral transition in an expanding quark-anti-quark plasma. The calculations are made within a linear sigma model with explicit quark and antiquark degrees of freedom. We solve numerically the classical equations of motion for chiral fields coupled to the fluid dynamical equations for the plasma. Fast initial growth and strong oscillations of the chiral field and strong amplification of long wavelength modes of the pion field are observed in the course of the chiral transition.Comment: 9 pages LaTeX, 4 postscript figure

    Dapagliflozin stimulates glucagon secretion at high glucose: experiments and mathematical simulations of human A-cells.

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    Glucagon is one of the main regulators of blood glucose levels and dysfunctional stimulus secretion coupling in pancreatic A-cells is believed to be an important factor during development of diabetes. However, regulation of glucagon secretion is poorly understood. Recently it has been shown that Na(+)/glucose co-transporter (SGLT) inhibitors used for the treatment of diabetes increase glucagon levels in man. Here, we show experimentally that the SGLT2 inhibitor dapagliflozin increases glucagon secretion at high glucose levels both in human and mouse islets, but has little effect at low glucose concentrations. Because glucagon secretion is regulated by electrical activity we developed a mathematical model of A-cell electrical activity based on published data from human A-cells. With operating SGLT2, simulated glucose application leads to cell depolarization and inactivation of the voltage-gated ion channels carrying the action potential, and hence to reduce action potential height. According to our model, inhibition of SGLT2 reduces glucose-induced depolarization via electrical mechanisms. We suggest that blocking SGLTs partly relieves glucose suppression of glucagon secretion by allowing full-scale action potentials to develop. Based on our simulations we propose that SGLT2 is a glucose sensor and actively contributes to regulation of glucagon levels in humans which has clinical implications

    Quasi-Dynamic Frame Coordination For Ultra- Reliability and Low-Latency in 5G TDD Systems

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    The fifth generation (5G) mobile technology features the ultra-reliable and low-latency communications (URLLC) as a major service class. URLLC applications demand a tight radio latency with extreme link reliability. In 5G dynamic time division duplexing (TDD) systems, URLLC requirements become further challenging to achieve due to the severe and fast-varying cross link interference (CLI) and the switching time of the radio frame configurations (RFCs). In this work, we propose a quasi-dynamic inter-cell frame coordination algorithm using hybrid frame design and a cyclic-offset-based RFC code-book. The proposed solution adaptively updates the RFCs in time such that both the average CLI and the user-centric radio latency are minimized. Compared to state-of-the-art dynamic TDD studies, the proposed scheme shows a significant improvement in the URLLC outage latency, i.e., 92% reduction gain, while boosting the cell-edge capacity by 189% and with a greatly reduced coordination overhead space, limited to B-bit

    Repair Scheduling in Wireless Distributed Storage with D2D Communication

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    We consider distributed storage (DS) for a wireless network where mobile devices arrive and depart according to a Poisson random process. Content is stored in a number of mobile devices, using an erasure correcting code. When requesting a piece of content, a user retrieves the content from the mobile devices using device-to-device communication or, if not possible, from the base station (BS), at the expense of a higher communication cost. We consider the repair problem when a device that stores data leaves the network. In particular, we introduce a repair scheduling where repair is performed (from storage devices or the BS) periodically. We derive analytical expressions for the overall communication cost of repair and download as a function of the repair interval. We illustrate the analysis by giving results for maximum distance separable codes and regenerating codes. Our results indicate that DS can reduce the overall communication cost with respect to the case where content is only downloaded from the BS, provided that repairs are performed frequently enough. The required repair frequency depends on the code used for storage and the network parameters. In particular, minimum bandwidth regenerating codes require very frequent repairs, while maximum distance separable codes give better performance if repair is performed less frequently. We also show that instantaneous repair is not always optimal.Comment: To be presented at IEEE Information Theory Workshop (ITW) 2015, Jeju Island, Korea, October 201

    Distributed Storage in Mobile Wireless Networks with Device-to-Device Communication

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    We consider the use of distributed storage (DS) to reduce the communication cost of content delivery in wireless networks. Content is stored (cached) in a number of mobile devices using an erasure correcting code. Users retrieve content from other devices using device-to-device communication or from the base station (BS), at the expense of higher communication cost. We address the repair problem when a device storing data leaves the cell. We introduce a repair scheduling where repair is performed periodically and derive analytical expressions for the overall communication cost of content download and data repair as a function of the repair interval. The derived expressions are then used to evaluate the communication cost entailed by DS using several erasure correcting codes. Our results show that DS can reduce the communication cost with respect to the case where content is downloaded only from the BS, provided that repairs are performed frequently enough. If devices storing content arrive to the cell, the communication cost using DS is further reduced and, for large enough arrival rate, it is always beneficial. Interestingly, we show that MDS codes, which do not perform well for classical DS, can yield a low overall communication cost in wireless DS.Comment: After final editing for publication in TCO

    A study of flux lines lattice order and critical current with time of flight small angle neutron scattering

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    Small angle neutron scattering (SANS) is an historical technique to study the flux lines lattice (FLL) in a superconductor. Structural characteristics of the FLL can be revealed, providing fundamental information for the physics of vortex lattice. However, the spatial resolution is limited and all the correlation lengths of order are difficult to extract with precision. We show here that a time of flight technique reveals the Bragg peak of the FLL, and also its translational order with a better resolution. We discuss the implication of these results for pinning mechanisms in a Niobium sample.Comment: accepted in PR

    Artificial Intelligence: Application Today and Implications Tomorrow

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    This paper analyzes the applications of artificial intelligence to the legal industry, specifically in the fields of legal research and contract drafting. First, it will look at the implications of artificial intelligence (A.I.) for the current practice of law. Second, it will delve into the future implications of A.I. on law firms and the possible regulatory challenges that come with A.I. The proliferation of A.I. in the legal sphere will give laymen (clients) access to the information and services traditionally provided exclusively by attorneys. With an increase in access to these services will come a change in the role that lawyers must play. A.I. is a tool that will increase access to cheaper and more efficient services, but non-lawyers lack the training to analyze and understand information it puts out. The role of lawyers will change to fill this role, namely utilizing these tools to create a better work product with greater efficiency for their clients

    Centralized and Distributed Solutions for Fast Muting Adaptation in LTE-Advanced HetNets

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    A codesign case study: implementing arithmetic functions in FPGAs

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    Different way of implementing and designing arithmetic functions for 16/32 bit integers in FPGA technology are studied. This also includes a comparison of four different design methods. The results are used to increase the overall system performance in a dedicated 3D image analysis prototype system by moving a vector length calculation from software to hardware. The conclusion is that by adding one relatively simple board containing two FPGA's in the prototype setup, the total computing time is reduced by 30 %. The total amount of image data, in this case 300 Mbyte which has to be transmitted via network, is reduced by a factor of two, and the required network bandwidth is reduced similarly. 1 Introduction This paper describes and analyses different ways of designing and implementing the arithmetic functions X 2 + Y 2 and p Z, where X and Y are 16 bit integers and Z is a 32 bit integer, in FPGA 1 technology. In a prototype setup, there is 2.5 ÂŻs available for calculating the..
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