19,064 research outputs found

    Compressibility and probabilistic proofs

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    We consider several examples of probabilistic existence proofs using compressibility arguments, including some results that involve Lov\'asz local lemma.Comment: Invited talk for CiE 2017 (full version

    Divergence functions in Information Geometry

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    A recently introduced canonical divergence D\mathcal{D} for a dual structure (g,∇,∇∗)(\mathrm{g},\nabla,\nabla^*) is discussed in connection to other divergence functions. Finally, open problems concerning symmetry properties are outlined.Comment: 10 page

    Nd-doped aluminum oxide integrated amplifiers at 880 nm, 1060 nm, and 1330 nm

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    Neodymium-doped Al2O3 layers were deposited on thermally oxidized Si substrates and channel waveguides were patterned using reactive-ion etching. Internal net gain on the Nd3+ transitions at 880, 1064, and 1330 nm was investigated,\ud yielding a maximum gain of 6.3 dB/cm at 1064 nm. Values for the energy-transfer upconversion parameter for different Nd3+\ud concentrations were deduced

    Complexity Measures from Interaction Structures

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    We evaluate new complexity measures on the symbolic dynamics of coupled tent maps and cellular automata. These measures quantify complexity in terms of kk-th order statistical dependencies that cannot be reduced to interactions between k−1k-1 units. We demonstrate that these measures are able to identify complex dynamical regimes.Comment: 11 pages, figures improved, minor changes to the tex

    Unusual Large Sporadic Angiomyolipoma Co-existing with Huge Simple Renal Cyst

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    Renal Angiomyolipoma (AML) is an unusual benign mesenchymal tumor with no malignant potential. It is composed of adipose tissue, smooth muscle and abnormal thick walled blood vessels. It can occur sporadically or may be associated with tuberous sclerosis. Sporadic angiomyolipoma (AML) coexisting with simple renal cyst is extremely rare and only one case report is available in the literature. In our case, unique combination of sporadic AML along with simple renal cyst with huge size and weight was noted. To the best of our knowledge, ours is the second such case and first case from India. Due to its large size, complete nephrectomy was performed to avoid chances of rupture and retroperitoneal hemorrhage. Post-operative period was uneventful and the patient ahs been on regular follow-up

    Quantifying structure in networks

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    We investigate exponential families of random graph distributions as a framework for systematic quantification of structure in networks. In this paper we restrict ourselves to undirected unlabeled graphs. For these graphs, the counts of subgraphs with no more than k links are a sufficient statistics for the exponential families of graphs with interactions between at most k links. In this framework we investigate the dependencies between several observables commonly used to quantify structure in networks, such as the degree distribution, cluster and assortativity coefficients.Comment: 17 pages, 3 figure

    Widely wavelength-selective Al2O3:Er3+ ring laser

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    Integrated Al2O3:Er3+ channel waveguide ring lasers were realized on thermally oxidized silicon substrates. High pump power coupling into- and low output power coupling from the ring is achieved in a straightforward design. Wavelength\ud selection in the range 1532 to 1557 nm was demonstrated by\ud varying the length of the output coupler from the ring

    Transport and Loss of Ring Current Electrons Inside Geosynchronous Orbit During the 17 March 2013 Storm.

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    Ring current electrons (1-100 keV) have received significant attention in recent decades, but many questions regarding their major transport and loss mechanisms remain open. In this study, we use the four-dimensional Versatile Electron Radiation Belt code to model the enhancement of phase space density that occurred during the 17 March 2013 storm. Our model includes global convection, radial diffusion, and scattering into the Earth's atmosphere driven by whistler-mode hiss and chorus waves. We study the sensitivity of the model to the boundary conditions, global electric field, the electric field associated with subauroral polarization streams, electron loss rates, and radial diffusion coefficients. The results of the code are almost insensitive to the model parameters above 4.5 R E R E, which indicates that the general dynamics of the electrons between 4.5 R E and the geostationary orbit can be explained by global convection. We found that the major discrepancies between the model and data can stem from the inaccurate electric field model and uncertainties in lifetimes. We show that additional mechanisms that are responsible for radial transport are required to explain the dynamics of ≄40-keV electrons, and the inclusion of the radial diffusion rates that are typically assumed in radiation belt studies leads to a better agreement with the data. The overall effect of subauroral polarization streams on the electron phase space density profiles seems to be smaller than the uncertainties in other input parameters. This study is an initial step toward understanding the dynamics of these particles inside the geostationary orbit

    Reliable low-cost fabrication of low-loss Al2O3:Er3+Al_2O_3:Er^{3+} waveguides with 5.4-dB optical gain

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    A reliable and reproducible deposition process for the fabrication of Al2O3Al_2O_3 waveguides with losses as low as 0.1 dB/cm has been developed. The thin films are grown at ~ 5 nm/min deposition rate and exhibit excellent thickness uniformity within 1% over 50times50 mm2 area and no detectable OH−OH^{-} incorporation. For applications of the Al2O3Al_2O_3 films in compact, integrated optical devices, a high-quality channel waveguide fabrication process is utilized. Planar and channel propagation losses as low as 0.1 and 0.2 dB/cm, respectively, are demonstrated. For the development of active integrated optical functions, the implementation of rare-earth-ion doping is investigated by cosputtering of erbium during the Al2O3Al_2O_3 layer growth. Dopant levels between 0.2-5times 1020cm−31020 cm^{-3} are studied. At Er3+Er^{3+} concentrations of interest for optical amplification, a lifetime of the 4I13/2 level as long as 7 ms is measured. Gain measurements over 6.4-cm propagation length in a 700-nm-thick Al2O3:Er3+Al_2O_3:Er^{3+} channel waveguide result in net optical gain over a 41-nm-wide wavelength range between 1526-1567 nm with a maximum of 5.4 dB at 1533 n

    The Added Value of Water Footprint Assessment for National Water Policy: A Case Study for Morocco

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    A Water Footprint Assessment is carried out for Morocco, mapping the water footprint of different activities at river basin and monthly scale, distinguishing between surface- and groundwater. The paper aims to demonstrate the added value of detailed analysis of the human water footprint within a country and thorough assessment of the virtual water flows leaving and entering a country for formulating national water policy. Green, blue and grey water footprint estimates and virtual water flows are mainly derived from a previous grid-based (5×5 arc minute) global study for the period 1996–2005. These estimates are placed in the context of monthly natural runoff and waste assimilation capacity per river basin derived from Moroccan data sources. The study finds that: (i) evaporation from storage reservoirs is the second largest form of blue water consumption in Morocco, after irrigated crop production; (ii) Morocco’s water and land resources are mainly used to produce relatively low-value (in US/m3andUS/m3 and US/ha) crops such as cereals, olives and almonds; (iii) most of the virtual water export from Morocco relates to the export of products with a relatively low economic water productivity (in US$/m3); (iv) blue water scarcity on a monthly scale is severe in all river basins and pressure on groundwater resources by abstractions and nitrate pollution is considerable in most basins; (v) the estimated potential water savings by partial relocation of crops to basins where they consume less water and by reducing water footprints of crops down to benchmark levels are significant compared to demand reducing and supply increasing measures considered in Morocco’s national water strateg
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