Design of Superconducting Spoke Cavities for High-Velocity Applications

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β0 ~ 0.15 to β0 ~ 0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β0 = 0.8 and β0 = 1

Interaction of reed and acoustic resonator in clarinetlike systems

Sound emergence in clarinetlike instruments is investigated in terms of instability of the static regime. Various models of reed-bore coupling are considered, from the pioneering work of Wilson and Beavers ["Operating modes of the clarinet", J. Acoust. Soc. Am. 56, 653--658 (1974)] to more recent modeling including viscothermal bore losses and vena contracta at the reed inlet. The pressure threshold above which these models may oscillate as well as the frequency of oscillation at threshold are calculated. In addition to Wilson and Beavers' previous conclusions concerning the role of the reed damping in the selection of the register the instrument will play on, the influence of the reed motion induced flow is also emphasized, particularly its effect on playing frequencies, contributing to reduce discrepancies between Wilson and Beavers' experimental results and theory, despite discrepancies still remain concerning the pressure threshold. Finally, analytical approximations of the oscillating solution based on Fourier series expansion are obtained in the vicinity of the threshold of oscillation. This allows to emphasize the conditions which determine the nature of the bifurcation (direct or inverse) through which the note may emerge, with therefore important consequences on the musical playing performances

hybridModels: An R Package for the Stochastic Simulation of Disease Spreading in Dynamic Networks

Disease spreading simulations are traditionally performed using coupled differential equations. However, in the setting of metapopulations, most of the solutions provided by this method do not account for the dynamic topography of subpopulations. Conversely, the alternative approach of individual-based modeling (IBM) may add computational cost and complexity. Hybrid models allow for the study of disease spreading because they combine both aforementioned approaches by separating them across different scales: a local scale that addresses subpopulation dynamics using coupled differential equations and a global scale that addresses the contact between these subpopulations using IBM. We present a simple way of simulating the spread of disease in dynamic networks using the high-level statistical computational language R and the hybridModels package. We built four examples using disease spread models at the local scale in several different networks: an animal movement network; a three-node network, whose model solution using a stochastic simulation algorithm is compared with the ordinary differential equations approach; the commuting of individuals between patches, which we compare with the permanent migration of individuals; and the commuting of individuals within the metropolitan area of São Paulo

Risk related to pre–diabetes mellitus and diabetes mellitus in heart failure with reduced ejection fraction: insights from prospective comparison of ARNI with ACEI to determine impact on global mortality and morbidity in heart failure trial

Background—The prevalence of pre–diabetes mellitus and its consequences in patients with heart failure and reduced ejection fraction are not known. We investigated these in the Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure (PARADIGM-HF) trial. Methods and Results—We examined clinical outcomes in 8399 patients with heart failure and reduced ejection fraction according to history of diabetes mellitus and glycemic status (baseline hemoglobin A1c [HbA1c]: <6.0% [<42 mmol/mol], 6.0%–6.4% [42–47 mmol/mol; pre–diabetes mellitus], and ≥6.5% [≥48 mmol/mol; diabetes mellitus]), in Cox regression models adjusted for known predictors of poor outcome. Patients with a history of diabetes mellitus (n=2907 [35%]) had a higher risk of the primary composite outcome of heart failure hospitalization or cardiovascular mortality compared with those without a history of diabetes mellitus: adjusted hazard ratio, 1.38; 95% confidence interval, 1.25 to 1.52;P<0.001. HbA1c measurement showed that an additional 1106 (13% of total) patients had undiagnosed diabetes mellitus and 2103 (25%) had pre–diabetes mellitus. The hazard ratio for patients with undiagnosed diabetes mellitus (HbA1c, >6.5%) and known diabetes mellitus compared with those with HbA1c<6.0% was 1.39 (1.17–1.64); P<0.001 and 1.64 (1.43–1.87); P<0.001, respectively. Patients with pre–diabetes mellitus were also at higher risk (hazard ratio, 1.27 [1.10–1.47];P<0.001) compared with those with HbA1c<6.0%. The benefit of LCZ696 (sacubitril/valsartan) compared with enalapril was consistent across the range of HbA1c in the trial. Conclusions—In patients with heart failure and reduced ejection fraction, dysglycemia is common and pre–diabetes mellitus is associated with a higher risk of adverse cardiovascular outcomes (compared with patients with no diabetes mellitus and HbA1c <6.0%). LCZ696 was beneficial compared with enalapril, irrespective of glycemic status

Development of Superconducting 500 MHZ Multi-Spoke Cavity for Electron Linacs

Multi-spoke cavities are well-known options for acceleration of heavy and light ions. A recently developed multi-spoke cavity for β=1 presents an attractive opportunity to use this cavity type for electron accelerators. One of the main attractive features of this cavity type is its compactness for relatively low frequency. A simplified design at 500 MHz allowed building of a multi-spoke cavity and cryomodule in a 2-year time frame with confidence and development of effective manufacturing techniques. It also constitutes an important step in proving the usefulness of this kind of cavity design for new applications in the electron machines. Niowave is now in a position to build on the success of this cavity to help advance the design of superconducting electron accelerators. Accelerating voltage of more then 4.3 MV in a single cavity at 4.5 K is expected with peak electric field of less then 21.7 MV/m, and peak magnetic field of less then 80 mT. The paper discusses the fabrication challenges of the complete cavity and the cryomodule, as well as room temperature and cryogenic test results

The extinction law in high redshift galaxies

We estimate the dust extinction laws in two intermediate redshift galaxies. The dust in the lens galaxy of LBQS1009-0252, which has an estimated lens redshift of zl~0.88, appears to be similar to that of the SMC with no significant feature at 2175 A. Only if the lens galaxy is at a redshift of zl~0.3, completely inconsistent with the galaxy colors, luminosity or location on the fundamental plane, can the data be fit with a normal Galactic extinction curve. The dust in the zl=0.68 lens galaxy for B0218+357, whose reddened image lies behind a molecular cloud, requires a very flat ultraviolet extinction curve with (formally) R(V)=12 +- 2. Both lens systems seem to have unusual extinction curves by Galactic standards.Comment: 15 pages, 3 figures. ApJ in pres

Groupoids and an index theorem for conical pseudo-manifolds

We define an analytical index map and a topological index map for conical pseudomanifolds. These constructions generalize the analogous constructions used by Atiyah and Singer in the proof of their topological index theorem for a smooth, compact manifold $M$. A main ingredient is a non-commutative algebra that plays in our setting the role of $C_0(T^*M)$. We prove a Thom isomorphism between non-commutative algebras which gives a new example of wrong way functoriality in $K$-theory. We then give a new proof of the Atiyah-Singer index theorem using deformation groupoids and show how it generalizes to conical pseudomanifolds. We thus prove a topological index theorem for conical pseudomanifolds

North America’s oldest boreal trees are more efficient water users due to increased [CO2], but do not grow faster

Due to anthropogenic emissions and changes in land use, trees are now exposed to atmospheric levels of [CO2] that are unprecedented for 650,000 y [Lüthi et al. (2008) Nature 453:379–382] (thousands of tree generations). Trees are expected to acclimate by modulating leaf–gas exchanges and alter water use efficiency which may result in forest productivity changes. Here, we present evidence of one of the strongest, nonlinear, and unequivocal postindustrial increases in intrinsic water use efficiency (iWUE) ever documented (+59%). A dual-isotope tree-ring analysis (δ13C and δ18O) covering 715 y of growth of North America’s oldest boreal trees (Thuja occidentalis L.) revealed an unprecedented increase in iWUE that was directly linked to elevated assimilation rates of CO2 (A). However, limited nutrient availability, changes in carbon allocation strategies, and changes in stomatal density may have offset stem growth benefits awarded by the increased iWUE. Our results demonstrate that even in scenarios where a positive CO2 fertilization effect is observed, other mechanisms may prevent trees from assimilating and storing supplementary anthropogenic emissions as above-ground biomass. In such cases, the sink capacity of forests in response to changing atmospheric conditions might be overestimated

The evolution of clusters in the CLEF cosmological simulation: X-ray structural and scaling properties

We present results from a study of the X-ray cluster population that forms within the CLEF cosmological hydrodynamics simulation, a large N-body/SPH simulation of the Lambda CDM cosmology with radiative cooling, star formation and feedback. The scaled projected temperature and entropy profiles at z=0 are in good agreement with recent high-quality observations of cool core clusters, suggesting that the simulation grossly follows the processes that structure the intracluster medium (ICM) in these objects. Cool cores are a ubiquitous phenomenon in the simulation at low and high redshift, regardless of a cluster's dynamical state. This is at odds with the observations and so suggests there is still a heating mechanism missing from the simulation. Using a simple, observable measure of the concentration of the ICM, which correlates with the apparent mass deposition rate in the cluster core, we find a large dispersion within regular clusters at low redshift, but this diminishes at higher redshift, where strong "cooling-flow" systems are absent in our simulation. Consequently, our results predict that the normalisation and scatter of the luminosity-temperature relation should decrease with redshift; if such behaviour turns out to be a correct representation of X-ray cluster evolution, it will have significant consequences for the number of clusters found at high redshift in X-ray flux-limited surveys.Comment: 20 pages, 21 figures, MNRAS, accepted with minor modifications to original manuscrip

Bregman Voronoi Diagrams: Properties, Algorithms and Applications

The Voronoi diagram of a finite set of objects is a fundamental geometric structure that subdivides the embedding space into regions, each region consisting of the points that are closer to a given object than to the others. We may define many variants of Voronoi diagrams depending on the class of objects, the distance functions and the embedding space. In this paper, we investigate a framework for defining and building Voronoi diagrams for a broad class of distance functions called Bregman divergences. Bregman divergences include not only the traditional (squared) Euclidean distance but also various divergence measures based on entropic functions. Accordingly, Bregman Voronoi diagrams allow to define information-theoretic Voronoi diagrams in statistical parametric spaces based on the relative entropy of distributions. We define several types of Bregman diagrams, establish correspondences between those diagrams (using the Legendre transformation), and show how to compute them efficiently. We also introduce extensions of these diagrams, e.g. k-order and k-bag Bregman Voronoi diagrams, and introduce Bregman triangulations of a set of points and their connexion with Bregman Voronoi diagrams. We show that these triangulations capture many of the properties of the celebrated Delaunay triangulation. Finally, we give some applications of Bregman Voronoi diagrams which are of interest in the context of computational geometry and machine learning.Comment: Extend the proceedings abstract of SODA 2007 (46 pages, 15 figures