1,436 research outputs found

    On the Frequency Dependency of Radio Channel's Delay Spread: Analyses and Findings From mmMAGIC Multi-frequency Channel Sounding

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    This paper analyzes the frequency dependency of the radio propagation channel's root mean square (rms) delay spread (DS), based on the multi-frequency measurement campaigns in the mmMAGIC project. The campaigns cover indoor, outdoor, and outdoor-to-indoor (O2I) scenarios and a wide frequency range from 2 to 86 GHz. Several requirements have been identified that define the parameters which need to be aligned in order to make a reasonable comparison among the different channel sounders employed for this study. A new modelling approach enabling the evaluation of the statistical significance of the model parameters from different measurements and the establishment of a unified model is proposed. After careful analysis, the conclusion is that any frequency trend of the DS is small considering its confidence intervals. There is statistically significant difference from the 3GPP New Radio (NR) model TR 38.901, except for the O2I scenario.Comment: This paper has been accepted to the 2018 12th European Conference on Antennas and Propagation (EuCAP), London, UK, April 201

    A 115,000-year-old expedient bone technology at Lingjing, Henan, China

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    Activities attested since at least 2.6 Myr, such as stone knapping, marrow extraction, and woodworking may have allowed early hominins to recognize the technological potential of discarded skeletal remains and equipped them with a transferable skillset fit for the marginal modification and utilization of bone flakes. Identifying precisely when and where expedient bone tools were used in prehistory nonetheless remains a challenging task owing to the multiple natural and anthropogenic processes that can mimic deliberately knapped bones. Here, we compare a large sample of the faunal remains from Lingjing, a 115 ka-old site from China which has yielded important hominin remains and rich faunal and lithic assemblages, with bone fragments produced by experimentally fracturing Equus caballus long bones. Our results provide a set of qualitative and quantitative criteria that can help zooarchaeologists and bone technologists distinguish faunal remains with intentional flake removal scars from those resulting from carcass processing activities. Experimental data shows marrow extraction seldom generates diaphyseal fragments bearing more than six flake scars arranged contiguously or in interspersed series. Long bone fragments presenting such characteristics can, therefore, be interpreted as being purposefully knapped to be used as expediency tools. The identification, based on the above experimental criteria, of 56 bone tools in the Lingjing faunal assemblage is consistent with the smaller size of the lithics found in the same layer. The continuity gradient observed in the size of lithics and knapped bones suggests the latter were used for tasks in which the former were less or not effective.publishedVersio

    Fish oil-based emulsion for the treatment of parenteral nutrition associated liver disease in an adult patient

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    Background & aims: Reversal of parenteral nutrition associated liver disease with fish oil emulsion (FO) has been reported in infants. We report a similar case in an adult patient. Methods: A 58 year-old female on home parenteral nutrition for a short bowel syndrome due to Crohn's disease, showed a progressive worsening of liver steatosis, and a persistent increase of the plasma liver function tests (LFTs). LFTs, serum alpha-tochopherol, red blood cell membrane fatty acids and liver histology were evaluated before and after an 8 month treatment with FO. Results: The patient's LFT's improved. There was an increase of the n-3 and a decrease of the n-6 series of fatty acids in erythrocyte membrane. There was an approximate 30% increase in vitamin E status. Before FO, liver histology showed a non-alcoholic steatohepatitis with grade 2 steatosis and inflammation and stage 3 fibrosis. After the treatment, steatosis and inflammation were grade 1, whereas fibrosis remained at stage 3. Conclusions: Infusion of FO was associated with consistent changes of cell membrane fatty acid structure and with mild improvement of vitamin E status. A potential role of FO in decreasing liver steatosis and inflammation with no change of liver fibrosis might be suggested. © 2010 European Society for Clinical Nutrition and Metabolism

    On the order of BEC transition in weakly interacting gases predicted by mean-field theory

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    Predictions from Hartree-Fock (HF), Popov (P), Yukalov-Yukalova (YY) and tt-matrix approximations regarding the thermodynamics from the normal to the BEC phase in weakly interacting Bose gases are considered. By analyzing the dependence of the chemical potential μ\mu on temperature TT and particle density ρ\rho we show that none of them predicts a second-order phase transition as required by symmetry-breaking general considerations. In this work we find that the isothermal compressibility κT\kappa_{T} predicted by these theories does not diverge at criticality as expected in a true second-order phase transition. Moreover the isotherms μ=μ(ρ,T)\mu=\mu(\rho,T) typically exhibit a non-singled valued behavior in the vicinity of the BEC transition, a feature forbidden by general thermodynamic principles. This behavior can be avoided if a first order phase transition is appealed. The facts described above show that although these mean field approximations give correct results near zero temperature they are endowed with thermodynamic anomalies in the vicinity of the BEC transition. We address the implications of these results in the interpretation of current experiments with ultracold trapped alkali gases.Comment: 16 pages, 5 figure

    Coarse-Graining the Lin-Maldacena Geometries

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    The Lin-Maldacena geometries are nonsingular gravity duals to degenerate vacuum states of a family of field theories with SU(2|4) supersymmetry. In this note, we show that at large N, where the number of vacuum states is large, there is a natural `macroscopic' description of typical states, giving rise to a set of coarse-grained geometries. For a given coarse-grained state, we can associate an entropy related to the number of underlying microstates. We find a simple formula for this entropy in terms of the data that specify the geometry. We see that this entropy function is zero for the original microstate geometries and maximized for a certain ``typical state'' geometry, which we argue is the gravity dual to the zero-temperature limit of the thermal state of the corresponding field theory. Finally, we note that the coarse-grained geometries are singular if and only if the entropy function is non-zero.Comment: 29 pages, LaTeX, 3 figures; v2 references adde

    Detection of Zak phases and topological invariants in a chiral quantum walk of twisted photons

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    Topological insulators are fascinating states of matter exhibiting protected edge states and robust quantized features in their bulk. Here, we propose and validate experimentally a method to detect topological properties in the bulk of one-dimensional chiral systems. We first introduce the mean chiral displacement, and we show that it rapidly approaches a multiple of the Zak phase in the long time limit. Then we measure the Zak phase in a photonic quantum walk, by direct observation of the mean chiral displacement in its bulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe, and combine the two windings to characterize the full phase diagram of this Floquet system. Finally, we prove the robustness of the measure by introducing dynamical disorder in the system. This detection method is extremely general, as it can be applied to all one-dimensional platforms simulating static or Floquet chiral systems.Comment: 10 pages, 7 color figures (incl. appendices) Close to the published versio

    A new cylindrical borehole detector for radiographic imaging with muons

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    Muon radiography is a methodology which enables measuring the mass distribution within large objects. It exploits the abundant flux of cosmic muons and uses detectors with different technologies depending on the application. As the sensitive surface and geometric acceptance are two fundamental parameters for increasing the collection of muons, the optimization of the detectors is very significant. Here we show a potentially innovative detector of size and shape suitable to be inserted inside a borehole, that optimizes the sensitive area and maximizes the angular acceptance thanks to its cylindrical geometry obtained using plastic arc-shaped scintillators. Good spatial resolution is obtained with a reasonable number of channels. The dimensions of the detector make it ideal for use in 25 cm diameter wells. Detailed simulations based on Monte Carlo methods show great cavity detection capability. The detector has been tested in the laboratory, achieving overall excellent performance

    Localization and Expression of Osteopontin in Mineralized and Nonmineralized Tissues of the Periodontium a

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72134/1/j.1749-6632.1995.tb44628.x.pd
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