Bi-stochastic kernels via asymmetric affinity functions

In this short letter we present the construction of a bi-stochastic kernel p for an arbitrary data set X that is derived from an asymmetric affinity function {\alpha}. The affinity function {\alpha} measures the similarity between points in X and some reference set Y. Unlike other methods that construct bi-stochastic kernels via some convergent iteration process or through solving an optimization problem, the construction presented here is quite simple. Furthermore, it can be viewed through the lens of out of sample extensions, making it useful for massive data sets.Comment: 5 pages. v2: Expanded upon the first paragraph of subsection 2.1. v3: Minor changes and edits. v4: Edited comments and added DO

Nonlinear Dynamics of Composite Plates and Shells

The equations of refined geometrically nonlinear theory of dynamic deformation of flexible with respect to transversal shear and compression ofplates and shells are proposed. The solutions for problems of transversal nonlinear vibrations of hinge fixedplate-strip are obtained. Numerical results are compared with the known in literature

The mechanical and microstructural behaviour of calcite-dolomite composites: An experimental investigation

The styles and mechanisms of deformation associated with many variably dolomitized limestone shear systems are strongly controlled by strain partitioning between dolomite and calcite. Here, we present experimental results from the deformation of four composite materials designed to address the role of dolomite on the strength of limestone. Composites were synthesized by hot isostatic pressing mixtures of dolomite (Dm) and calcite powders (% Dm: 25%-Dm, 35%-Dm, 51%-Dm, and 75%-Dm). In all composites, calcite is finer grained than dolomite. The synthesized materials were deformed in torsion at constant strain rate (3 × 10−4 and 1 × 10−4 s−1), high effective pressure (262 MPa), and high temperature (750 °C) to variable finite shear strains. Mechanical data show an increase in yield strength with increasing dolomite content. Composites with 50%) dolomite content samples, the addition of 25% fine-grained calcite significantly weakens dolomite, such that strain can be partially localized along narrow ribbons of fine-grained calcite. Deformation of dolomite grains by shear fracture is observed; there is no intracrystalline deformation in dolomite irrespective of its relative abundance and finite shear strain

Mesoscopic scattering of spin s particles

Quantum effects in weakly disordered systems are governed by the properties of the elementary interaction between propagating particles and impurities. Long range mesoscopic effects due to multiple scattering are derived by iterating the single scattering vertex, which has to be appropriately diagonalized. In the present contribution, we present a systematic and detailed diagonalisation of the diffuson and cooperon vertices responsible for weak localisation effects. We obtain general expressions for eigenvalues and projectors onto eigenmodes, for any spin and arbitrary elementary interaction with impurities. This description provides a common frame for a unified theory of mesoscopic spin physics for electrons, photons, and other quantum particles. We treat in detail the case of spin-flip scattering of electrons by freely orientable magnetic impurities and briefly review the case of photon scattering from degenerate dipole transitions in cold atomic gases.Comment: published version, with a new figure and new section

Барботажные химические эффекты: их виды, механизмы возникновения и геохимические проявления

Експериментально досліджено зміни значень pH і Eh у воді і водних розчинах NaCl при 20 ºС під час пропускання чистих газів (N2, O2, повітря без CO2) в різних режимах барботажу. Результати проаналізовано з врахуванням сучасних уявлень про структуру рідкої води і її поверхні (інтерфейсу). Як правило, барботажний процес складається із двох етапів: I – перші 10 хвилин із швидким збільшенням значення рН і зменшенням значення Eh внаслідок вимивання розчинених CO2 і O2; II – до 2–3 годин, коли значення Eh продовжує повільно зменшуватись, а значення pH може як зростати (лужний БХЕ) так і зменшуватись (кислотний БХЕ), що вказує на кислотний характер поверхні газ/вода і утворених при барботажі аерозолів. Спеціальні досліди на магнітній мішалці показали, що помітні зміни pH і Eh починаються лише після переходу перемішування із ламінарного режиму в турбулентний, що приводить до значного підвищення структурної температури води і відповідного зменшення розчинності кисню та величини Eh. Це і є основна причина змін на першому етапі барботажу, який можна назвати турбулентним БХЕ. Окремо потрібно виділити диференціацію йонів під час барботажу у змішаних розчинах солей. Для пояснення явища йонного БХЕ запропонована і обґрунтовано гіпотезу нейтральних йонних пар, яка задовільно пояснює генезис і властивості морських аерозолів.The changes of pH and Eh in water and aqueous NaCl – solutions at 20 °C during the transmission of pure gases (N2, O2, air, CO22) in different modes of barbotage are experimentally investigated. The results are analyzed taking into account modern notions of the structure of liquid water and its surface (interface). Generally, the barbotage process consists of two stages: I – the first 10 minutes with the rapid increasing in pH and decreasing in Eh due to leaching of dissolved CO2 and O2; II – up to 2-3 hours when Eh continues to decrease slowly, but pH can increase (alkaline BCE) or decrease (acid BCE), indicating the acidic nature of gas/water surface and aerosols produced during barbotage. Special experiments on the magnetic stirrer showed that noticeable changes in pH and Eh begin only after the transition from laminar regime of mixing to turbulent, which leads to a significant increasing of the structural temperature of water and a corresponding reduction in the solubility of oxygen and Eh values. This is the main reason for the changes at the first step of barbotage, which can be called as the turbulent BCE. We must highlight the differentiation of ions during barbotage in mixed salt solutions. To explain this phenomenon of ion BCE, the hypothesis of neutral ion pairs has been proposed and substantiated, which satisfactorily explains the genesis and properties of marine aerosols.Экспериментально исследованы изменения значений pH и Eh в воде и водных растворах NaCl при 20 ºС во время пропускания чистых газов (N2, O2, воздуха без CO2) в различных режимах барботажа. Результаты проанализированы с учетом современных представлений о структуре жидкой воды и ее поверхности (интерфейса). Как правило, барботажный процесс состоит из двух этапов: I – первые 10 минут с быстрым увеличением значений рН и уменьшением Eh, вследствие вымывания растворенных CO2 и O2; II – до 2-3 часов, когда Eh продолжают медленно уменьшаться, а pH может как расти (щелочной БХЕ) так и уменьшаться (кислотный БХЕ), что указывает на кислотный характер поверхности раздела фаз газ/вода и аэрозолей, образованных при барботаже. Специальные опыты на магнитной мешалке показали, что заметные изменения значений pH и Eh начинаются только после перехода перемешивания из ламинарного режима в турбулентный, что приводит к значительному повышению структурной температуры воды и соответствует уменьшению растворимости кислорода и величины Eh. Это и есть основная причина изменений на первом этапе барботажа, который можно назвать турбулентным БХЕ. Отдельно нужно выделить дифференциацию ионов при барботаже в смешанных растворах солей. Для объяснения этого явления ионного БХЕ предложена и обоснована гипотеза нейтральных ионных пар, которая удовлетворительно объясняет генезис и свойства морских аэрозолей

Galaxy Clusters as Reservoirs of Heavy Dark Matter and High-Energy Cosmic Rays: Constraints from Neutrino Observations

Galaxy Clusters (GCs) are the largest reservoirs of both dark matter and cosmic rays (CRs). Dark matter self-annihilation can lead to a high luminosity in gamma rays and neutrinos, enhanced by a strong degree of clustering in dark matter substructures. Hadronic CR interactions can also lead to a high luminosity in gamma rays and neutrinos, enhanced by the confinement of CRs from cluster accretion/merger shocks and active galactic nuclei. We show that IceCube/KM3Net observations of high-energy neutrinos can probe the nature of GCs and the separate dark matter and CR emission processes, taking into account how the results depend on the still-substantial uncertainties. Neutrino observations are relevant at high energies, especially at >10 TeV. Our results should be useful for improving experimental searches for high-energy neutrino emission. Neutrino telescopes are sensitive to extended sources formed by dark matter substructures and CRs distributed over large scales. Recent observations by Fermi and imaging atmospheric Cherenkov telescopes have placed interesting constraints on the gamma-ray emission from GCs. We also provide calculations of the gamma-ray fluxes, taking into account electromagnetic cascades inside GCs, which can be important for injections at sufficiently high energies. This also allows us to extend previous gamma-ray constraints to very high dark matter masses and significant CR injections at very high energies. Using both neutrinos and gamma rays, which can lead to comparable constraints, will allow more complete understandings of GCs. Neutrinos are essential for some dark matter annihilation channels, and for hadronic instead of electronic CRs. Our results suggest that the multi-messenger observations of GCs will be able to give useful constraints on specific models of dark matter and CRs. [Abstract abridged.]Comment: 31 pages, 20 figures, 1 table, accepted for publication in JCAP, references and discussions adde

Intercomparison of the northern hemisphere winter mid-latitude atmospheric variability of the IPCC models

We compare, for the overlapping time frame 1962-2000, the estimate of the northern hemisphere (NH) mid-latitude winter atmospheric variability within the XX century simulations of 17 global climate models (GCMs) included in the IPCC-4AR with the NCEP and ECMWF reanalyses. We compute the Hayashi spectra of the 500hPa geopotential height fields and introduce an integral measure of the variability observed in the NH on different spectral sub-domains. Only two high-resolution GCMs have a good agreement with reanalyses. Large biases, in most cases larger than 20%, are found between the wave climatologies of most GCMs and the reanalyses, with a relative span of around 50%. The travelling baroclinic waves are usually overestimated, while the planetary waves are usually underestimated, in agreement with previous studies performed on global weather forecasting models. When comparing the results of various versions of similar GCMs, it is clear that in some cases the vertical resolution of the atmosphere and, somewhat unexpectedly, of the adopted ocean model seem to be critical in determining the agreement with the reanalyses. The GCMs ensemble is biased with respect to the reanalyses but is comparable to the best 5 GCMs. This study suggests serious caveats with respect to the ability of most of the presently available GCMs in representing the statistics of the global scale atmospheric dynamics of the present climate and, a fortiori, in the perspective of modelling climate change.Comment: 39 pages, 8 figures, 2 table

Relationship between serum testosterone and fracture risk in men: a comparison of RIA and LC-MS/MS

BACKGROUND: Serum testosterone can be measured byLC-MS/MS and RIA. We investigated whether the testosterone–fracture relationship was affected by the method of measurement. METHODS: We measured total testosterone (TT) by LCMS/MS (TTLC-MS/MS) and RIA (TTRIA) in serum samples collected from 602 men whose incident fractures had been continuously ascertained by x-ray reports from 1989 to 2010. We measured bone mineral density (BMD) by dual-energy x-ray absorptiometry. The association between TT and fracture risk was assessed by the Cox proportional hazards model, taking into account the effect of age and BMD. CONCLUSIONS: The concordance between LC-MS/MS and RIA in the measurement of serum TT was moderate. Moreover, the magnitude of association between testosterone and fracture risk in older men was largely unaffected by the method of measurement. © 2015 American Association for Clinical Chemistr

Magnetic fields and Sunyaev-Zel'dovich effect in galaxy clusters

In this work we study the contribution of magnetic fields to the Sunyaev Zeldovich (SZ) effect in the intracluster medium. In particular we calculate the SZ angular power spectrum and the central temperature decrement. The effect of magnetic fields is included in the hydrostatic equilibrium equation by splitting the Lorentz force into two terms one being the force due to magnetic pressure which acts outwards and the other being magnetic tension which acts inwards. A perturbative approach is adopted to solve for the gas density profile for weak magnetic fields (< 4 micro G}). This leads to an enhancement of the gas density in the central regions for nearly radial magnetic field configurations. Previous works had considered the force due to magnetic pressure alone which is the case only for a special set of field configurations. However, we see that there exists possible sets of configurations of ICM magnetic fields where the force due to magnetic tension will dominate. Subsequently, this effect is extrapolated for typical field strengths (~ 10 micro G) and scaling arguments are used to estimate the angular power due to secondary anisotropies at cluster scales. In particular we find that it is possible to explain the excess power reported by CMB experiments like CBI, BIMA, ACBAR at l > 2000 with sigma_8 ~ 0.8 (WMAP 5 year data) for typical cluster magnetic fields. In addition we also see that the magnetic field effect on the SZ temperature decrement is more pronounced for low mass clusters ( ~ 2 keV). Future SZ detections of low mass clusters at few arc second resolution will be able to probe this effect more precisely. Thus, it will be instructive to explore the implications of this model in greater detail in future works.Comment: 20 pages, 8 figure