151 research outputs found

    Цена золота и инфляция.

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    В статье проведено исследование взаимосвязи цен на золото и инфляционных процессов с применением корреляционно-регрессионного анализа. В предложенной модели учитывается одновременное влияние ценовых колебаний золота со значениями временного лага 0, 1 и2 на уровень инфляции. Анализ проводился с использованием статистических данных США и Великобритании, так как национальные рынки золота данных государств играют весомую роль на мировом рынке золота. В результате проведенного анализа установлена форма и сила связи между ценовыми изменениями золота и индексом потребительских цен. = In the article it is shown research of interrelation ofthe gold prices and inflationary processes with ap-plication the correlated regression analysis. In the offered model is considered simultaneous influence of gold price fluctuations with values of a time lag 0, 1 and 2 on a rate of inflation. The analysis was spent on the statistical given USA and the Great Britain, as the national gold markets of the states play a powerful role at the world gold market. As a result of the spent analysis is established the form and force of interrelation between gold price changes and a consumer price index

    Компьютерное прогнозирование спектров биологической активности химических соединений: возможности и ограничения

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    oai:www.bmc-rm.org:article/4An essential characteristic of chemical compounds is their biological activity since its presence can become the basis for the use of the substance for therapeutic purposes, or, on the contrary, limit the possibilities of its practical application due to the manifestation of side action and toxic effects. Computer assessment of the biological activity spectra makes it possible to determine the most promising directions for the study of the pharmacological action of particular substances, and to filter out potentially dangerous molecules at the early stages of research. For more than 25 years, we have been developing and improving the computer program PASS (Prediction of Activity Spectra for Substances), designed to predict the biological activity spectrum of substance based on the structural formula of its molecules. The prediction is carried out by the analysis of structure-activity relationships for the training set, which currently contains information on structures and known biological activities for more than one million molecules. The structure of the organic compound is represented in PASS using Multilevel Neighborhoods of Atoms descriptors; the activity prediction for new compounds is performed by the naive Bayes classifier and the structure-activity relationships determined by the analysis of the training set. We have created and improved both local versions of the PASS program and freely available web resources based on PASS (http://www.way2drug.com). They predict several thousand biological activities (pharmacological effects, molecular mechanisms of action, specific toxicity and adverse effects, interaction with the unwanted targets, metabolism and action on molecular transport), cytotoxicity for tumor and non-tumor cell lines, carcinogenicity, induced changes of gene expression profiles, metabolic sites of the major enzymes of the first and second phases of xenobiotics biotransformation, and belonging to substrates and/or metabolites of metabolic enzymes. The web resource Way2Drug is used by over 19 000 researchers from more than 100 countries around the world, which allowed them to obtain over 600 000 predictions and publish about 500 papers describing the obtained results. The analysis of the published works shows that in some cases the interpretation of the prediction results presented by the authors of these publications requires an adjustment. In this work, we provide the theoretical basis and consider, on particular examples, the opportunities and limitations of computer-aided prediction of biological activity spectra.Важной характеристикой химических соединений является их биологическая активность, поскольку ее наличие может стать основой для использования вещества в терапевтических целях, либо, напротив, ограничить возможности его практического применения вследствие проявления побочных и токсических эффектов. Компьютерная оценка спектра биологической активности дает возможность определить наиболее перспективные направления для тестирования фармакологического действия конкретных веществ и отсеять потенциально опасные молекулы на ранних стадиях исследований. Свыше 25 лет нами осуществляется разработка и совершенствование компьютерной программы PASS (Prediction of Activity Spectra for Substances), предназначенной для прогнозирования спектра биологической активности вещества по структурной формуле его молекул. Прогноз осуществляется на основе анализа зависимостей «структура-активность» для соединений обучающей выборки, в настоящее время содержащей информацию о структурах и известных видах биологической активности более чем для миллиона молекул. Описание структуры молекул органического соединения реализовано в PASS посредством дескрипторов атомных окрестностей (Multilevel Neighborhoods of Atoms), прогнозирование активности для новых соединений выполняется алгоритмом на основе «наивного Байесовского подхода» и зависимостей «структура-активность», выявляемых при анализе обучающей выборки. Нами созданы и совершенствуются как локальные версии программы PASS, так и свободно доступные в Интернет веб-ресурсы на основе PASS (http://way2drug.com): прогноз нескольких тысяч видов биологической активности (фармакологические эффекты, молекулярные механизмы действия, специфическая токсичность и побочное действие, метаболизм, а также влияние на нежелательные мишени, молекулярный транспорт, генную экспрессию), прогноз цитотоксичности для опухолевых и неопухолевых клеточных линий, прогноз канцерогенности, прогноз индуцированных органическими соединениями изменений профилей экспрессии генов, прогноз взаимодействия с ферментами метаболизма лекарств, в том числе прогноз сайтов метаболизма, а также прогноз принадлежности к субстратам и/или метаболитам этих ферментов. Веб-ресурс Way2Drug используют свыше 19 тысяч исследователей более чем из 100 стран мира, что позволило им осуществить свыше 600 тысяч прогнозов и опубликовать около 500 работ с описанием полученных результатов. Анализ опубликованных работ показывает, что в некоторых случаях приводимая авторами этих публикаций интерпретация результатов прогноза требует корректировки. В рамках настоящей работы мы представим теоретическое обоснование и рассмотрим на конкретных примерах возможности и ограничения компьютерного прогнозирования спектров биологической активности

    Nuclear Spin-Isospin Correlations, Parity Violation, and the fπf_\pi Problem

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    The strong interaction effects of isospin- and spin-dependent nucleon-nucleon correlations observed in many-body calculations are interpreted in terms of a one-pion exchange mechanism. Including such effects in computations of nuclear parity violating effects leads to enhancements of about 10%. A larger effect arises from the one-boson exchange nature of the parity non-conserving nucleon- nucleon interaction, which depends on both weak and strong meson-nucleon coupling constants. Using values of the latter that are constrained by nucleon-nucleon phase shifts leads to enhancements of parity violation by factors close to two. Thus much of previously noticed discrepancies between weak coupling constants extracted from different experiments can be removed.Comment: 8 pages 2 figures there should have been two figures in v

    Second harmonic generation and birefringence of some ternary pnictide semiconductors

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    A first-principles study of the birefringence and the frequency dependent second harmonic generation (SHG) coefficients of the ternary pnictide semiconductors with formula ABC2_2 (A = Zn, Cd; B = Si, Ge; C = As, P) with the chalcopyrite structures was carried out. We show that a simple empirical observation that a smaller value of the gap is correlated with larger value of SHG is qualitatively true. However, simple inverse power scaling laws between gaps and SHG were not found. Instead, the real value of the nonlinear response is a result of a very delicate balance between different intraband and interband terms.Comment: 13 pages, 12 figure

    Probing CP Violation with the Deuteron Electric Dipole Moment

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    We present an analysis of the electric dipole moment (EDM) of the deuteron as induced by CP-violating operators of dimension 4, 5 and 6 including theta QCD, the EDMs and color EDMs of quarks, four-quark interactions and the Weinberg operator. We demonstrate that the precision goal of the EDM Collaboration's proposal to search for the deuteron EDM, (1-3)\times 10^{-27} e cm, will provide an improvement in sensitivity to these sources of one-two orders of magnitude relative to the existing bounds. We consider in detail the level to which CP-odd phases can be probed within the MSSM.Comment: 5 pages, 4 figures; precision estimates clarified, to appear in Phys. Rev.

    Further evidence for a variable fine-structure constant from Keck/HIRES QSO absorption spectra

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    [Abridged] We previously presented evidence for a varying fine-structure constant, alpha, in two independent samples of Keck/HIRES QSO spectra. Here we present a detailed many-multiplet analysis of a third Keck/HIRES sample containing 78 absorption systems. We also re-analyse the previous samples, providing a total of 128 absorption systems over the redshift range 0.2<z_abs<3.7. All three samples separately yield consistent, significant values of da/a. The analyses of low- and high-z systems rely on different ions/transitions with very different dependencies on alpha, yet they also give consistent results. We identify additional random errors in 22 high-z systems characterized by transitions with a large dynamic range in apparent optical depth. Increasing the statistical errors on da/a for these systems gives our fiducial result, a weighted mean da/a=(-0.543+/-0.116)x10^-5, representing 4.7-sigma evidence for a smaller weighted mean alpha in the absorption clouds. Assuming that da/a=0 at z_abs=0, the data marginally prefer a linear increase in alpha with time: dota/a=(6.40+/-1.35)x10^-16 yr^-1. The two-point correlation function for alpha is consistent with zero over 0.2-13 Gpc comoving scales and the angular distribution of da/a shows no significant dipolar anisotropy. We therefore have no evidence for spatial variations in da/a. We extend our previous searches for possible systematic errors, identifying atmospheric dispersion and isotopic structure effects as potentially the most significant. However, overall, known systematic errors do not explain the results. Future many-multiplet analyses of QSO spectra from different telescopes and spectrographs will provide a now crucial check on our Keck/HIRES results.Comment: 31 pages, 25 figures (29 EPS files), 8 tables. Accepted by MNRAS. Colour versions of Figs. 6, 8 & 10 and text version of Table 3 available at http://www.ast.cam.ac.uk/~mim/pub.htm

    Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation

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    The current status of electric dipole moments of diamagnetic atoms which involves the synergy between atomic experiments and three different theoretical areas -- particle, nuclear and atomic is reviewed. Various models of particle physics that predict CP violation, which is necessary for the existence of such electric dipole moments, are presented. These include the standard model of particle physics and various extensions of it. Effective hadron level combined charge conjugation (C) and parity (P) symmetry violating interactions are derived taking into consideration different ways in which a nucleon interacts with other nucleons as well as with electrons. Nuclear structure calculations of the CP-odd nuclear Schiff moment are discussed using the shell model and other theoretical approaches. Results of the calculations of atomic electric dipole moments due to the interaction of the nuclear Schiff moment with the electrons and the P and time-reversal (T) symmetry violating tensor-pseudotensor electron-nucleus are elucidated using different relativistic many-body theories. The principles of the measurement of the electric dipole moments of diamagnetic atoms are outlined. Upper limits for the nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained combining the results of atomic experiments and relativistic many-body theories. The coefficients for the different sources of CP violation have been estimated at the elementary particle level for all the diamagnetic atoms of current experimental interest and their implications for physics beyond the standard model is discussed. Possible improvements of the current results of the measurements as well as quantum chromodynamics, nuclear and atomic calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for EPJ

    Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

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    We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

    Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

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