1,692 research outputs found

    Valuing Spectrum Allocations

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    Observing trends in which Wi-Fi and Bluetooth have become widely popular, some argue that unlicensed allocations hosting such wireless technologies are increasingly valuable and that administrative spectrum allocations should shift accordingly. We challenge that policy conclusion. A core issue is that the social value of a given spectrum allocation is widely assumed to equal the gains of the applications it is likely to host. This thinking is faulty, as vividly seen in what we deem the Broadcast TV Spectrum Valuation Fallacy – the idea that because wireless video, or broadcast network programs are popular, TV channels are efficiently defined. This approach has been appropriately rejected, in key instances, by spectrum regulators, but is similarly applied in other instances regarding unlicensed allocations. While traditional allocations have garnered widespread criticism for imposing rigid barriers tending to block innovation, and flexible-use spectrum access rights have gained favor, the regulatory methods used to allocate (or reallocate) bandwidth remain embedded in a “command and control” process. Reconfiguring spectrum usage to enable emerging wireless markets often requires lengthy, costly rule makings. The expense of this administrative overhead is generally omitted from spectrum allocation policy analysis. Yet, it constitutes an essential component of the consumer welfare analysis. We propose a more fulsome policy approach, one that includes not only the appropriate measures of marginal value and opportunity cost for rival allocations, but incorporates transaction costs. Instead of regulators attempting to guess how much bandwidth should be allocated to various types of licensed and unlicensed services – and imposing different rules within and across these allocations – a more generic approach is called for. By better enabling spontaneous adjustments to changing consumer demands and technological innovation, spectrum allocations can be more efficiently brought into their most valuable employments

    Valuing Spectrum Allocations

    Get PDF
    Observing trends in which Wi-Fi and Bluetooth have become widely popular, some argue that unlicensed allocations hosting such wireless technologies are increasingly valuable and that administrative spectrum allocations should shift accordingly. We challenge that policy conclusion. A core issue is that the social value of a given spectrum allocation is widely assumed to equal the gains of the applications it is likely to host. This thinking is faulty, as vividly seen in what we deem the Broadcast TV Spectrum Valuation Fallacy – the idea that because wireless video, or broadcast network programs are popular, TV channels are efficiently defined. This approach has been appropriately rejected, in key instances, by spectrum regulators, but is similarly applied in other instances regarding unlicensed allocations. While traditional allocations have garnered widespread criticism for imposing rigid barriers tending to block innovation, and flexible-use spectrum access rights have gained favor, the regulatory methods used to allocate (or reallocate) bandwidth remain embedded in a “command and control” process. Reconfiguring spectrum usage to enable emerging wireless markets often requires lengthy, costly rule makings. The expense of this administrative overhead is generally omitted from spectrum allocation policy analysis. Yet, it constitutes an essential component of the consumer welfare analysis. We propose a more fulsome policy approach, one that includes not only the appropriate measures of marginal value and opportunity cost for rival allocations, but incorporates transaction costs. Instead of regulators attempting to guess how much bandwidth should be allocated to various types of licensed and unlicensed services – and imposing different rules within and across these allocations – a more generic approach is called for. By better enabling spontaneous adjustments to changing consumer demands and technological innovation, spectrum allocations can be more efficiently brought into their most valuable employments

    Optical Conductivity in Mott-Hubbard Systems

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    We study the transfer of spectral weight in the optical spectra of a strongly correlated electron system as a function of temperature and interaction strength. Within a dynamical mean field theory of the Hubbard model that becomes exact in the limit of large lattice coordination, we predict an anomalous enhancement of spectral weight as a function of temperature in the correlated metallic state and report on experimental measurements which agree with this prediction in V2O3V_2O_3. We argue that the optical conductivity anomalies in the metal are connected to the proximity to a crossover region in the phase diagram of the model.Comment: 12 pages and 4 figures, to appear in Phys. Rev. Lett., v 75, p 105 (1995

    A Computational Simulation Study of Benzamidine Derivatives Binding to Arginine-Specific Gingipain (HRgpA) from Periodontopathogen Porphyromonas gingivalis

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    We have shown that the binding free energy calculation from molecular dynamics can be adapted successfully to cysteine proteinases, such as arginine-specific gingipain (HRgpA) from Porphyromonas gingivalis. The binding free energy obtained is in good agreement with the available experimental data for eight benzamidine derivatives including urea and ether linker. The calculations showed that the electrostatic energies between HRgpA and inhibitors were important in determining the relative affinities of the inhibitors to the HRgpA, with an average binding free energy of about −5 kcal/mol. The average structures of the eight complexes suggest that benzamidine inhibitors interact with Asp387, His435, and Cys468 by hydrogen bonding and with Trp508 by hydrophilic interactions that are essential for the activities of benzamidine inhibitors. It can therefore be expected that the method provides a reliable tool for the investigation of new HRgpA inhibitors. This finding could significantly benefit the future design of HRgpA inhibitors

    Information and communication technology solutions for outdoor navigation in dementia

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    INTRODUCTION: Information and communication technology (ICT) is potentially mature enough to empower outdoor and social activities in dementia. However, actual ICT-based devices have limited functionality and impact, mainly limited to safety. What is an ideal operational framework to enhance this field to support outdoor and social activities? METHODS: Review of literature and cross-disciplinary expert discussion. RESULTS: A situation-aware ICT requires a flexible fine-tuning by stakeholders of system usability and complexity of function, and of user safety and autonomy. It should operate by artificial intelligence/machine learning and should reflect harmonized stakeholder values, social context, and user residual cognitive functions. ICT services should be proposed at the prodromal stage of dementia and should be carefully validated within the life space of users in terms of quality of life, social activities, and costs. DISCUSSION: The operational framework has the potential to produce ICT and services with high clinical impact but requires substantial investment

    26Al kinematics: superbubbles following the spiral arms? : Constraints from the statistics of star clusters and HI supershells

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    High energy resolution spectroscopy of the 1.8 MeV radioactive decay line of 26Al with the SPI instrument on board the INTEGRAL satellite has recently revealed that diffuse 26Al has large velocities in comparison to other components of the interstellar medium in the Milky Way. 26Al shows Galactic rotation in the same sense as the stars and other gas tracers, but reaches excess velocities up to 300 km s−1Peer reviewe

    Genome wide association and linkage analyses identified three loci-4q25, 17q23.2, and 10q11.21-associated with variation in leukocyte telomere length: The long life family study

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    Leukocyte telomere length is believed to measure cellular aging in humans, and short leukocyte telomere length is associated with increased risks of late onset diseases, including cardiovascular disease, dementia, etc. Many studies have shown that leukocyte telomere length is a heritable trait, and several candidate genes have been identified, including TERT, TERC, OBFC1, and CTC1. Unlike most studies that have focused on genetic causes of chronic diseases such as heart disease and diabetes in relation to leukocyte telomere length, the present study examined the genome to identify variants that may contribute to variation in leukocyte telomere length among families with exceptional longevity. From the genome wide association analysis in 4,289 LLFS participants, we identified a novel intergenic SNP rs7680468 located near PAPSS1 and DKK2 on 4q25 (p = 4.7E-8). From our linkage analysis, we identified two additional novel loci with HLOD scores exceeding three, including 4.77 for 17q23.2, and 4.36 for 10q11.21. These two loci harbor a number of novel candidate genes with SNPs, and our gene-wise association analysis identified multiple genes, including DCAF7, POLG2, CEP95, and SMURF2 at 17q23.2; and RASGEF1A, HNRNPF, ANF487, CSTF2T, and PRKG1 at 10q11.21. Among these genes, multiple SNPs were associated with leukocyte telomere length, but the strongest association was observed with one contiguous haplotype in CEP95 and SMURF2. We also show that three previously reported genes—TERC, MYNN, and OBFC1—were significantly associated with leukocyte telomere length at p(empirical) < 0.05
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