15,630 research outputs found

    Optimal technology policy: subsidies versus monitoring

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    We analyze the optimal technology policy to solve a free-riding problem between the members of a RJV. We assume that when intervening the Government suffers an additional adverse selection problem because it is not able to distinguish the value of the potential innovation. Although subsidies and monitoring may be equivalent policy tools to solve firms' free-riding problem, they imply different social losses if the Government is not able to perfectly distinguish the value of the potential innovation. The supremacy of monitoring tools over subsidies is proved to depend on which type of information the Government is able to obtain about firms' R&D performance.RJV, moral hazard, adverse selection, subsidies, monitoring

    Combining dark matter detectors and electron-capture sources to hunt for new physics in the neutrino sector

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    In this letter we point out the possibility to study new physics in the neutrino sector using dark matter detectors based on liquid xenon. These are characterized by very good spatial resolution and extremely low thresholds for electron recoil energies. When combined with a radioactive Îœe\nu_e source, both features in combination allow for a very competitive sensitivity to neutrino magnetic moments and sterile neutrino oscillations. We find that, for realistic values of detector size and source strength, the bound on the neutrino magnetic moment can be improved by an order of magnitude with respect to the present value. Regarding sterile neutrino searches, we find that most of the gallium anomaly could be explored at the 95% confidence level just using shape information.Comment: 5 pages, 2 figures. Minor modifications, references added. Version accepted for publication in JHE

    A generic radio channel emulator to evaluate higher layer protocols in a CDMA system

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    Currently, we are involved in the standardisation process to specify the next mobile system generation. A wideband code division multiple access (WCDMA) system is considered in most of the region versions. It would be very useful to count on a radio channel emulator which allows one to evaluate higher layers protocols within this context. This paper presents a radio channel emulator developed for a code division multiple access (CDMA) based system. Its versatility and low complexity have been exposed, and the validation process to check the model accuracy has also been shown for this system as an example.Peer ReviewedPostprint (published version

    Contemporaneity of Spain rural architecture intervention and economic sustainability

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    From the second half of the 20th century onwards, Spanish rural architecture has suffered a transformation regarding its farming and ranching model. The economic unsustainability of the family economy has led to further action for the viability of the system. This transformation has meant a new mindset to the owner of the farm and livestock, who had to consider whether continuity was given to the exploitation or the countryside/field was changed and adapted to a new use such as rural tourism, restoration, or for collective uses such as holiday camps, cultural centers or others. Owners who have decided to continue the exploitation they were developing have had to industrialize it and thus extend it in a considerable percentage. That has meant the need to intervene significantly in the rural architectural heritage. A wide and varied range of results has been obtained in these interventions: from the fossilization or destruction of assets, to the achievement of harmony and coexistence between tradition and modernity in this heritage, the result of which represents the contemporaneity of rural architecture.Peer ReviewedPostprint (published version

    A radio channel emulator for WCDMA, based on the hidden Markov model (HMM)

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    One of the main development and research subjects within the telecommunications area activity is the 3G mobile systems standardisation. The radio access is, of course, the main trouble in mobile systems, so it is important to investigate its implication. This paper describes a radio channel emulator for the UTRA-FDD made, based on the hidden Markov model (HMM). Since a statistical system behaviour is needed to train the HMM, off-line simulations have been made. The results between simulated and emulated statistics are presented. The use of emulation models implies a loss of accuracy with respect to simulation models, but is adequate to operate in real time. Certainly, the main advantage of using HMM in the emulator is the huge reduction in time, resources and effort with regard to a real simulation of the system. The emulator will allow in future works, for fast testing and comparison of several higher layer protocols and error control schemes.Peer ReviewedPostprint (published version

    Performance of a linear interference canceller for a ds/cdma synchronous system based on the ekf delay estimator

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    Since the conventional detector often fails to produce reliable decisions for a CDMA channel, several new multiuser detectors have previously proposed. In the present paper, the authors propose both a simple linear scheme for interference cancellation, which exhibits good performance, and a synchronism scheme based on the extended Kalman filter (EKF) to achieve synchronization among the different users at the base station, for a direct-sequence code-division multiple-access (DS/CDMA) synchronous system. The influence of the synchronism scheme on the performance of the interference canceller is analyzed under Rayleigh multipath fading.Peer ReviewedPostprint (published version

    On soft/hard handoff for packet data services in cellular CDMA mobiles systems

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    Benefits of macrodiversity operation for packet data services in third generation mobile systems are not obvious. Retransmission procedures to enhance link performance and higher downlink bandwidth requirements could question macrodiversity usage. This paper describes a simple methodology to compare soft and hard handoff performance in terms of transmission delay for packet data services. The handover procedures are based exclusively on power criteria and hysteresis margins.Peer ReviewedPostprint (published version

    Multiple slot allocation for voice/data transmission over PRMA++ applied to FRAMES multiple access mode 1

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    This paper presents some simulation results of PRMA++ for voice and data transmission over a physical air interface platform defined in the ACTS European project FRAMES. Variations on the statistics of speech sources (activity factor, petition rate) are studied and conclusions are obtained for optimal frame dimensioning. For data transmission, a multiple slot allocation scheme is presented and results are shown for different source rates and packet lengths.Peer ReviewedPostprint (published version

    Bipartite all-versus-nothing proofs of Bell's theorem with single-qubit measurements

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    If we distribute n qubits between two parties, which quantum pure states and distributions of qubits would allow all-versus-nothing (or Greenberger-Horne-Zeilinger-like) proofs of Bell's theorem using only single-qubit measurements? We show a necessary and sufficient condition for the existence of these proofs for any number of qubits, and provide all distinct proofs up to n=7 qubits. Remarkably, there is only one distribution of a state of n=4 qubits, and six distributions, each for a different state of n=6 qubits, which allow these proofs.Comment: REVTeX4, 4 pages, 2 figure
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