34,982 research outputs found

    Improving Resource Efficiency with Partial Resource Muting for Future Wireless Networks

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    We propose novel resource allocation algorithms that have the objective of finding a good tradeoff between resource reuse and interference avoidance in wireless networks. To this end, we first study properties of functions that relate the resource budget available to network elements to the optimal utility and to the optimal resource efficiency obtained by solving max-min utility optimization problems. From the asymptotic behavior of these functions, we obtain a transition point that indicates whether a network is operating in an efficient noise-limited regime or in an inefficient interference-limited regime for a given resource budget. For networks operating in the inefficient regime, we propose a novel partial resource muting scheme to improve the efficiency of the resource utilization. The framework is very general. It can be applied not only to the downlink of 4G networks, but also to 5G networks equipped with flexible duplex mechanisms. Numerical results show significant performance gains of the proposed scheme compared to the solution to the max-min utility optimization problem with full frequency reuse.Comment: 8 pages, 9 figures, to appear in WiMob 201

    Corneal alterations associated with pseudoexfoliation syndrome and glaucoma: A literature review

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    A systematic literature review was performed evaluating articles examining the effects of pseudoexfoliation syndrome (PEX) and glaucoma (PEXG) on the cornea with a focus on the corneal endothelium. We searched for articles relevant to pseudoexfoliation syndrome, pseudoexfoliation glaucoma and corneal endothelial cell counts using Pubmed, Google Scholar Database, Web of Science and cochrane Library databases published prior to September of 2016. We then screened the references of these retrieved papers and performed a Web of Science cited reference search. corneal characteristics analyzed included central corneal thickness (ccT), corneal nerve density, endothelial cell density (EcD), polymegathism, and pleomorphism. These parameters were compared in the following populations: control, PEX, PEXG, and primary open angle glaucoma (POAG). Over 30 observational studies were reviewed. Most studies showed a statistically significant lower EcD in PEX and PEXG populations compared to controls. Overall, PEX eyes had a non-statistically significant trend of lower EcDs compared to PEXG eyes. No consistent trends were found when analyzing differences in ccT amongst control, PEX and PEXG groups. For the few studies that looked at corneal nerve characteristics, the control groups were found to have statistically significantly greater nerve densities than PEX eyes, which had significantly greater densities than PEXG eyes. EcD and corneal nerve densities may be potential metrics for risk-stratifying patients with PEX and PEXG. Our literature review provided further evidence of the significant negative influence PEX has on the cornea, worsening as patients convert to PEXG

    Evidence for Multiple Pathways to Deuterium Enhancements in Protoplanetary Disks

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    The distributions of deuterated molecules in protoplanetary disks are expected to depend on the molecular formation pathways. We use observations of spatially resolved DCN emission from the disk around TW Hya, acquired during ALMA Science verification with a ~3" synthesized beam, together with comparable DCO+ observations from the Submillimeter Array, to investigate differences in the radial distributions of these species and hence differences in their formation chemistry. In contrast to DCO+, which shows an increasing column density with radius, DCN is better fit by a model that is centrally peaked. We infer that DCN forms at a smaller radii and thus at higher temperatures than DCO+. This is consistent with chemical network model predictions of DCO+ formation from H2D+ at T<30 K and DCN formation from additional pathways involving CH2D+ at higher temperatures. We estimate a DCN/HCN abundance ratio of ~0.017, similar to the DCO+/HCO+ abundance ratio. Deuterium fractionation appears to be efficient at a range of temperatures in this protoplanetary disk. These results suggest caution in interpreting the range of deuterium fractions observed in Solar System bodies, as multiple formation pathways should be taken into account.Comment: accepted for publication in Ap

    Fluctuations in Number of Cercospora beticola Conidia in Relationship to Environment and Disease Severity in Sugar Beet

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    All content of Phytopathology is open access without restriction 12 months after publicationCercospora leaf spot, caused by Cercospora beticola, is the most damaging foliar disease of sugar beet in Minnesota (MN) and North Dakota (ND). Research was conducted to characterize the temporal progression of aerial concentration of C. beticola conidia in association with the environment and disease severity in sugar beet. In 2003 and 2004, volumetric spore traps were placed within inoculated sugar beet plots to determine daily dispersal of conidia at Breckenridge, MN, and St. Thomas, ND. Plots were rated weekly for disease severity. At both locations, conidia were first collected in early July 2003 and late June in 2004. Peaks of conidia per cubic meter of air were observed with maxima in late August 2003 and in early September 2004 at both locations. Peaks of airborne conidium concentration were significantly correlated with the average temperature of daily hours when relative humidity was greater than 87%. Weekly mean hourly conidia per cubic meter of air was significantly (P <0.01) associated with disease severity during both years and across locations. This study showed that C. beticola conidial numbers may be used to estimate potential disease severity that, with further research, could be incorporated in a disease forecasting model to rationalize Cercospora leaf spot management.Peer reviewe

    On the Application of Gluon to Heavy Quarkonium Fragmentation Functions

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    We analyze the uncertainties induced by different definitions of the momentum fraction zz in the application of gluon to heavy quarkonium fragmentation function. We numerically calculate the initial g→J/ψg \to J / \psi fragmentation functions by using the non-covariant definitions of zz with finite gluon momentum and find that these fragmentation functions have strong dependence on the gluon momentum k⃗\vec{k}. As ∣k⃗∣→∞| \vec{k} | \to \infty, these fragmentation functions approach to the fragmentation function in the light-cone definition. Our numerical results show that large uncertainties remains while the non-covariant definitions of zz are employed in the application of the fragmentation functions. We present for the first time the polarized gluon to J/ψJ/\psi fragmentation functions, which are fitted by the scheme exploited in this work.Comment: 11 pages, 7 figures;added reference for sec.
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