Search of low-dimensional magnetics on the basis of structural data: spin-1/2 antiferromagnetic zigzag chain compounds In2VO5, beta-Sr(VOAsO4)2,(NH4,K)2VOF4 and alpha-ZnV3O8

A new technique for searching low-dimensional compounds on the basis of structural data is presented. The sign and strength of all magnetic couplings at distances up to 12 A in five predicted new antiferromagnetic zigzag spin-1/2 chain compounds In2VO5, beta-Sr(VOAsO4)2, (NH4)2VOF4, K2VOF4 and alpha-ZnV3O8 were calculated. It was stated that in the compound In2VO5 zigzag spin chains are frustrated, since the ratio (J2/J1) of competing antiferromagnetic (AF) nearest- (J1) and AF next-to-nearest-neighbour (J2) couplings is equal to 1.68 that exceeds the Majumdar-Ghosh point by 1/2. In other compounds the zigzag spin chains are AF magnetically ordered single chains as value of ratios J2/J1 is close to zero. The interchain couplings were analyzed in detail.Comment: 14 pages, 6 figure, 1 table, minor change

Physics Reach of High-Energy and High-Statistics IceCube Atmospheric Neutrino Data

This paper investigates the physics reach of the IceCube neutrino detector when it will have collected a data set of order one million atmospheric neutrinos with energies in the 0.1 \sim 10^4 TeV range. The paper consists of three parts. We first demonstrate how to simulate the detector performance using relatively simple analytic methods. Because of the high energies of the neutrinos, their oscillations, propagation in the Earth and regeneration due to \tau decay must be treated in a coherent way. We set up the formalism to do this and discuss the implications. In a final section we apply the methods developed to evaluate the potential of IceCube to study new physics beyond neutrino oscillations. Not surprisingly, because of the increased energy and statistics over present experiments, existing bounds on violations of the equivalence principle and of Lorentz invariance can be improved by over two orders of magnitude. The methods developed can be readily applied to other non-conventional physics associated with neutrinos.Comment: 21 pages, 7 figures, Revtex

Radiography of the Earth's Core and Mantle with Atmospheric Neutrinos

A measurement of the absorption of neutrinos with energies in excess of 10 TeV when traversing the Earth is capable of revealing its density distribution. Unfortunately, the existence of beams with sufficient luminosity for the task has been ruled out by the AMANDA South Pole neutrino telescope. In this letter we point out that, with the advent of second-generation kilometer-scale neutrino detectors, the idea of studying the internal structure of the Earth may be revived using atmospheric neutrinos instead.Comment: 4 pages, LaTeX file using RevTEX4, 2 figures and 1 table included. Matches published versio

Crystal chemistry search of multiferroics with the stereochemically active lone pair

On the basis of our previous studies of magnetoelectric ordering of BiFeO3, TbMnO3, TbMn2O5 and BiMn2O5 we formulate the crystal chemistry criteria for the search of multiferroics and reveal potential multiferroics Pb2Cu(OH)4Cl2, Pb5Cr3F19, Mn(SeO3){\dot}H2O and BiPbSr2MnO6 each containing the ion with a lone pair.Comment: 4 pages, 8 figures,submitted to J Supercond Nov Mag

ІННОВАЦІЙНИЙ МЕНЕДЖМЕНТ У РЕГІОНАЛЬНОМУ РОЗВИТКУ: МЕТОДОЛОГІЧНІ АСПЕКТИ

Formation of innovative economic model and effective regional policy necessitates the justification of methodological foundations of modern region`s management system. The purpose of the article is improving the components of the methodology of organizational and institutional development of the regional administration system that will promote the introduction of innovative management of socio-economic processes in regions. This article explores the structural differentiation, functional subsystems and process control systems to regional development, the necessity of reorienting its essence — content elements. Established that the underestimation of competence, creative and cultural aspects in modern system of innovation management is the most important reason for low level of professionalism and effective implementation of management functions. It is grounded most important components of innovation management in the region, institutional, cultural, cognitive, competence which use for modern development, make and implement strategic decisions on which can improve procedural and resource subsystem. Scientific novelty author has proposed a fundamentally new system — integration model of Regional Development. Its use will facilitate the formation of complex of integrated totality, which forms the system that has synergistic properties and able to provide the strategic development of the region. Practical significance has strategic integration of all subsystems of Innovation Management and proposed by the author organizational and institutional approach to ensure the future development of the region. The consistent use of these key components of the proposed model can provide science-based approach to innovation development of the strategic management of the economy of the region in conditions of modernization, introduction the effective regional policy.Формування інноваційної моделі економіки та ефективної регіональної політики зумовлює необхідність обґрунтування методологічних основ сучасного розвитку системи менеджменту регіонів. Мета статті — удосконалення складових методології організаційно-інституційного розвитку системи регіонального управління, що сприятиме запровадженню в регіонах інноваційного менеджменту соціально-економічних процесів. Досліджено розмежування структурної, функціональної і процесної підсистем системи управління регіональним розвитком, доведена необхідність переорієнтації її сутнісно-змістовних елементів. Установлено, що недооцінка компетентнісних, творчих і культурних аспектів у сучасній системі інноваційного менеджменту є найважливішою причиною слабкого рівня професіоналізму та ефективного здійснення управлінських функцій. Обґрунтовано найважливіші складові інноваційного менеджменту регіону: інституційна, культурна, когнітивна, компетентнісна, які покликані формувати сучасний розвиток, ухвалювати і реалізовувати стратегічні рішення, на основі яких отримають удосконалення ресурсна і процедурна підсистеми. Наукову новизну має запропонована принципово нова системно-інтеграційна модель органів управління розвитком регіону. Її застосування сприятиме формуванню складної інтегрованої сукупності, яка утворює систему, що володіє синергетичними властивостями і здатна забезпечити стратегічний розвиток регіону, Практичне значення має стратегічна інтеграція всіх підсистем інноваційного менеджменту та запропонований організаційно-інституціональний підхід для забезпечення перспективного розвитку регіону. Послідовне використання основних складових запропонованої моделі здатне забезпечити науково обґрунтований підхід до інноваційного розвитку системи стратегічного управління економікою регіону в умовах модернізації, впровадженню ефективної регіональної політики

NEUTRINOS FROM PRIMORDIAL BLACK HOLES

The emission of particles from black holes created in the early Universe has detectable astrophysical consequences. The most stringent bound on their abundance has been obtained from the absence of a detectable diffuse flux of 100 MeV photons. Further scrutiny of these bounds is of interest as they, for instance, rule out primordial black holes as a dark matter candidate. We here point out that these bounds can, in principle, be improved by studying the diffuse cosmic neutrino flux. Measurements of near-vertical atmospheric neutrino fluxes in a region of low geomagnetic latitude can provide a competitive bound. The most favorable energy to detect a possible diffuse flux of primordial black hole origin is found to be a few MeV. We also show that measurements of the diffuse $\nu _\tau$ flux is the most promising to improve the existing bounds deduced from gamma-ray measurements. Neutrinos from individual black hole explosions can be detected in the GeV-TeV energy region. We find that the kilometer-scale detectors, recently proposed, are able to establish competitive bounds.Comment: 19 pages plus 9 uuencoded and compressed postscript figure

Quasiparticle dynamics and phonon softening in FeSe superconductors

Quasiparticle dynamics of FeSe single crystals revealed by dual-color transient reflectivity measurements ({\Delta}R/R) provides unprecedented information on Fe-based superconductors. The amplitude of fast component in {\Delta}R/R clearly tells a competing scenario between spin fluctuations and superconductivity. Together with the transport measurements, the relaxation time analysis further exhibits anomalous changes at 90 K and 230 K. The former manifests a structure phase transition as well as the associated phonon softening. The latter suggests a previously overlooked phase transition or crossover in FeSe. The electron-phonon coupling constant {\lambda} is found to be 0.16, identical to the value of theoretical calculations. Such a small {\lambda} demonstrates an unconventional origin of superconductivity in FeSe.Comment: Final published version; 5 pages; 4 figure

Crystal chemistry aspects of the magnetically induced ferroelectricity in TbMn2O5 and BiMn2O5

The origin of magnetic frustration was stated and the ions whose shift is accompanied by emerging magnetic ordering and ferroelectricity in TbMn2O5 and BiMn2O5 were determined on the basis of calculation of magnetic coupling parameters by using the structural data. The displacements accompanying the magnetic ordering are not polar, they just induce changes of bond valence (charge disordering) of Mn1 and Mn2, thus creating instability of the crystal structure. To approximate again the bond valence to the initial value (charge ordering) under magnetic ordering conditions is possible only due to polar displacement of Mn2 (or O1) and O4 ions along the b axis that is the cause of ferroelectric transition.Comment: 17 pages, 3 figures, 5 table

Prompt neutrino fluxes from atmospheric charm

We calculate the prompt neutrino flux from atmospheric charm production by cosmic rays, using the dipole picture in a perturbative QCD framework, which incorporates the parton saturation effects present at high energies. We compare our results with the next-to-leading order perturbative QCD result and find that saturation effects are large for neutrino energies above 10^6 GeV, leading to a substantial suppression of the prompt neutrino flux. We comment on the range of prompt neutrino fluxes due to theoretical uncertainties.Comment: 13 pages with 11 figures; expanded discussion, added references, version to be published in Phys. Rev.

Granular Rheology in Zero Gravity

We present an experimental investigation on the rheological behavior of model granular media made of nearly elastic spherical particles. The experiments are performed in a cylindrical Couette geometry and the experimental device is placed inside an airplane undergoing parabolic flights to cancel the effect of gravity. The corresponding curves, shear stress versus shear rate, are presented and a comparison with existing theories is proposed. The quadratic dependence on the shear rate is clearly shown and the behavior as a function of the solid volume fraction of particles exhibits a power law function. It is shown that theoretical predictions overestimate the experiments. We observe, at intermediate volume fractions, the formation of rings of particles regularly spaced along the height of the cell. The differences observed between experimental results and theoretical predictions are discussed and related to the structures formed in the granular medium submitted to the external shear.Comment: 10 pages, 6 figures to be published in Journal of Physics : Condensed Matte