662 research outputs found
Abelian Landau-Pomeranchuk-Migdal effects
It is shown that the high-energy expansion of the scattering amplitude
calculated from Feynman diagrams factorizes in such a way that it can be
reduced to the eikonalized form up to the terms of inverse power in energy in
accordance with results obtained by solving the Klein-Gordon equation.
Therefore the two approaches when applied to the suppression of the emission of
soft photons by fast charged particles in dense matter should give rise to the
same results. A particular limit of thin targets is briefly discussed.Comment: 14 pages, LATEX, 1 Fig. ps, submitted to Mod. Phys. Lett.
Non-ergodic Intensity Correlation Functions for Blinking Nano Crystals
We investigate the non-ergodic properties of blinking nano-crystals using a
stochastic approach. We calculate the distribution functions of the time
averaged intensity correlation function and show that these distributions are
not delta peaked on the ensemble average correlation function values; instead
they are W or U shaped. Beyond blinking nano-crystals our results describe
non-ergodicity in systems stochastically modeled using the Levy walk framework
for anomalous diffusion, for example certain types of chaotic dynamics,
currents in ion-channel, and single spin dynamics to name a few.Comment: 5 pages, 3 figure
Fractional Quantum Mechanics
A path integral approach to quantum physics has been developed. Fractional
path integrals over the paths of the L\'evy flights are defined. It is shown
that if the fractality of the Brownian trajectories leads to standard quantum
and statistical mechanics, then the fractality of the L\'evy paths leads to
fractional quantum mechanics and fractional statistical mechanics. The
fractional quantum and statistical mechanics have been developed via our
fractional path integral approach. A fractional generalization of the
Schr\"odinger equation has been found. A relationship between the energy and
the momentum of the nonrelativistic quantum-mechanical particle has been
established. The equation for the fractional plane wave function has been
obtained. We have derived a free particle quantum-mechanical kernel using Fox's
H function. A fractional generalization of the Heisenberg uncertainty relation
has been established. Fractional statistical mechanics has been developed via
the path integral approach. A fractional generalization of the motion equation
for the density matrix has been found. The density matrix of a free particle
has been expressed in terms of the Fox's H function. We also discuss the
relationships between fractional and the well-known Feynman path integral
approaches to quantum and statistical mechanics.Comment: 27 page
Psi-Series Solution of Fractional Ginzburg-Landau Equation
One-dimensional Ginzburg-Landau equations with derivatives of noninteger
order are considered. Using psi-series with fractional powers, the solution of
the fractional Ginzburg-Landau (FGL) equation is derived. The leading-order
behaviours of solutions about an arbitrary singularity, as well as their
resonance structures, have been obtained. It was proved that fractional
equations of order with polynomial nonlinearity of order have the
noninteger power-like behavior of order near the singularity.Comment: LaTeX, 19 pages, 2 figure
Gravitational bending of light by planetary multipoles and its measurement with microarcsecond astronomical interferometers
General relativistic deflection of light by mass, dipole, and quadrupole
moments of gravitational field of a moving massive planet in the Solar system
is derived. All terms of order 1 microarcsecond are taken into account,
parametrized, and classified in accordance with their physical origin. We
calculate the instantaneous patterns of the light-ray deflections caused by the
monopole, the dipole and the quadrupole moments, and derive equations
describing apparent motion of the deflected position of the star in the sky
plane as the impact parameter of the light ray with respect to the planet
changes due to its orbital motion. The present paper gives the physical
interpretation of the observed light-ray deflections and discusses the
observational capabilities of the near-future optical (SIM) and radio (SKA)
interferometers for detecting the Doppler modulation of the radial deflection,
and the dipolar and quadrupolar light-ray bendings by the Jupiter and the
Saturn.Comment: 33 pages, 10 figures, accepted to Phys. Rev.
Fractional Variations for Dynamical Systems: Hamilton and Lagrange Approaches
Fractional generalization of an exterior derivative for calculus of
variations is defined. The Hamilton and Lagrange approaches are considered.
Fractional Hamilton and Euler-Lagrange equations are derived. Fractional
equations of motion are obtained by fractional variation of Lagrangian and
Hamiltonian that have only integer derivatives.Comment: 21 pages, LaTe
Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis
International audienceAerosols play an important role in the atmosphere but are poorly characterized, particularly in urban areas like the Mexico City Metropolitan Area (MCMA). The chemical composition of urban particles must be known to assess their effects on the environment, and specific particulate emissions sources should be identified to establish effective pollution control standards. For these reasons, samples of particulate matter ?2.5 ?m (PM2.5) were collected during the MCMA-2003 Field Campaign for elemental and multivariate analyses. Proton-Induced X-ray Emission (PIXE), Proton-Elastic Scattering Analysis (PESA) and Scanning Transmission Ion Microscopy (STIM) measurements were done to determine concentrations of 19 elements from Na to Pb, hydrogen, and total mass, respectively. The most abundant elements from PIXE analysis were S, Si, K, Fe, Ca, and Al, while the major emissions sources associated with these elements were industry, wind-blown soil, and biomass burning. Wind trajectories suggest that metals associated with industrial emissions came from northern areas of the city whereas soil aerosols came from the southwest and increased in concentration during dry conditions. Elemental markers for fuel oil combustion, V and Ni, correlated with a large SO2 plume to suggest an anthropogenic, rather than volcanic, emissions source. By subtracting major components of soil and sulfates determined by PIXE analysis from STIM total mass measurements, we estimate that approximately 50% of non-volatile PM2.5 consisted of carbonaceous material
Nitrative and Oxidative Stress in Toxicology and Disease
Persistent inflammation and the generation of reactive oxygen and nitrogen species play pivotal roles in tissue injury during disease pathogenesis and as a reaction to toxicant exposures. The associated oxidative and nitrative stress promote diverse pathologic reactions including neurodegenerative disorders, atherosclerosis, chronic inflammation, cancer, and premature labor and stillbirth. These effects occur via sustained inflammation, cellular proliferation and cytotoxicity and via induction of a proangiogenic environment. For example, exposure to the ubiquitous air pollutant ozone leads to generation of reactive oxygen and nitrogen species in lung macrophages that play a key role in subsequent tissue damage. Similarly, studies indicate that genes involved in regulating oxidative stress are altered by anesthetic treatment resulting in brain injury, most notable during development. In addition to a role in tissue injury in the brain, inflammation, and oxidative stress are implicated in Parkinson's disease, a neurodegenerative disease characterized by the loss of dopamine neurons. Recent data suggest a mechanistic link between oxidative stress and elevated levels of 3,4-dihydroxyphenylacetaldehyde, a neurotoxin endogenous to dopamine neurons. These findings have significant implications for development of therapeutics and identification of novel biomarkers for Parkinson's disease pathogenesis. Oxidative and nitrative stress is also thought to play a role in creating the proinflammatory microenvironment associated with the aggressive phenotype of inflammatory breast cancer. An understanding of fundamental concepts of oxidative and nitrative stress can underpin a rational plan of treatment for diseases and toxicities associated with excessive production of reactive oxygen and nitrogen species
ОПРЕДЕЛЕНИЕ ТЕМПОВ ИНФЛЯЦИИ В ИНВЕСТИЦИОННО-СТРОИТЕЛЬНОМ СЕКТОРЕ ЭКОНОМИКИ
The aim of the study: to show the complexity and heterogeneity of inflation processes, which break down into inflation processes of sectoral economies, to conduct a comparative analysis of prices using two-dimensional distributions, to show the difference between the inflationary component in the investment and construction sector of the economy from inflation indicators, used in everyday real estate valuation practice, to propose a method for calculating the level of inflation that appraisers could use independently, based on current market data.The system and comparative analysis, method of analogies, the content analysis were used as methods of the research. The main attention is paid to the use of multidimensional statistical analysis, the use of the logarithmically normal distribution model as distributions that adequately reflect the asymmetric empirical distribution of prices and convenient from a computational point of view, and the conclusion of the calculation formulas derived from the corresponding hypothesis. The latest data, published by Rosstat on the dynamics of prices for different groups of goods, as well as data from one of the construction companies of Saint Petersburg were used as statistical materials. The study is divided into the following stages: calculation of the inflation rate for the product group, based on the hypothesis of jointly logarithmically normal distribution of prices of the reference group of goods in the base year and in the year of comparison, as well as the hypothesis of logarithmically normal distribution of the weights of the consumer basket, comparison of the result with the official data, then a similar calculation of the inflation rate in the evaluation of objects in the investment and construction sector of the economy.Results: the authors propose a method of determining the rate of inflation in the evaluation of market value income approach based on statistical analysis of the market data. The method allows setting the estimated inflation rate, acceptable for the construction industry and the tasks of assessing the real estate income approach.Conclusion: In the evaluation of the real estate, it is necessary to study more thoroughly the sectoral inflation rates, since the forced use in the evaluation of the real estate data on inflation in the consumer sector is not always correct. General questions of the inflation rate estimation and deflator coefficients by the market data based on two-dimensional distributions of random variables are raised. Modern methods of big data processing, technical capabilities, a large number of software products on the market, the prospects of the digital economy pose the task of creating extensive and accessible to appraisers and analysts databases, equipped with analytical tools. The goal is difficult, because the carriers of reliable information (such as retail chains, for example) often avoid publicity. In this regard, there is a task to coordinate the efforts of the scientific community and business to solve common modern problems and challenges.Цель исследования: показать сложность и неоднородность инфляционных процессов, распадающихся на инфляционные процессы отраслевых экономик, провести сравнительный анализ цен с использованием двумерных распределений, показать отличие инфляционной составляющей в инвестиционно-строительном секторе экономики от показателей инфляции, применяемых в повседневной практике оценки недвижимого имущества, предложить метод расчета уровня инфляции, который практикующие оценщики могли бы применять самостоятельно, основываясь на текущих рыночных данных.Материалы и методы: В качестве методов выполненного исследования использовались системный и сравнительный анализ, метод аналогий, контентный анализ. Основное внимание уделяется применению многомерного статистического анализа, использованию модели логарифмически нормальных распределений, как распределений, достаточно адекватно отражающих ассиметричные эмпирические распределения цен и удобных с вычислительной точки зрения и выводу расчетных формул, вытекающих из соответствующей гипотезы. В качестве статистического материалы были использованы последние, опубликованные на момент написания статьи данные Росстата по динамике цен на различные группы товаров, а также данные одной из строительных организаций г.Санкт-Петербурга. Исследование разделено на следующие этапы: расчет уровня инфляцию цен товаров продуктовой группы, опирающийся на гипотезу о совместно логарифмически нормальном распределении цен референтной группы товаров в базовом году и в году сравнения, а также на гипотезу о логарифмически нормальном распределении весов потребительской корзины, сопоставление результата с официальными данными, затем аналогичный расчет темпов инфляции при оценке объектов в инвестиционно-строительном секторе экономики.Результаты: В статье предложен метод определения ставки инфляции при оценке рыночной стоимости доходным подходом на основе статистического анализа рыночных данных. Метод позволяет установить расчетный уровень инфляции, приемлемый для строительной отрасли и задач оценки недвижимого имущества доходным подходом.Заключение: Показано, что при оценке недвижимого имущества, необходимо более тщательное исследование секторальных темпов инфляции, так как вынужденное использование при оценке недвижимости данных по темпам инфляции в потребительском секторе экономики не всегда корректно. Затрагиваются и общие вопросы оценки уровня инфляции и коэффициентов дефляторов по рыночным данным, на основе двумерных распределений случайных величин. Современные методы обработки больших данных, технические возможности, большое количество программных продуктов, представленных на рынке, перспективы цифровой экономики ставят задачу создания обширных и доступных оценщикам и аналитикам баз данных, снабженных аналитическим инструментарием. Задача это сложная, так как носители достоверной информации (такие как торговые сети, например) зачастую избегают публичности. В этой связи возникает задача координации усилий научного сообщества и бизнеса, для решения общих современных задач и вызовов
Pilot tests of a catalyst for the selective hydrogenation of acetylene
Pilot tests of SGA-2M promoted Pd/Al2O3 catalyst in the selective hydrogenation of acetylene are performed on an industrial ethane-ethylene fraction in a system of two serially arranged adiabatic flow reactors. The optimum process conditions under which the conversion of acetylene reaches 100% at a selectivity of 68.2% with respect to ethylene are determined: system pressure, 21 atm; hydrocarbon feedstock hourly space velocity (HSV), 1500 h-1, carbon monoxide concentration, 7 ppm; H2: C 2H2 molar ratio at the first and second hydrogenation stages, 1.0: 1.0 and 1.4: 1.0; inlet temperature of the first and second reactors, 40 and 55 C, respectively. The interregeneration service life of the SGA-2M catalyst under optimum conditions is estimated at 12 months. SGA-2M catalysts can be recommended for purifying ethane-ethylene fractions containing up to 2 vol % of acetylene. © 2013 Pleiades Publishing, Ltd
- …