Short-range order and precipitation in Fe-rich Fe-Cr alloys: Atomistic off-lattice Monte Carlo simulations

Short-range order (SRO) in Fe-rich Fe-Cr alloys is investigated by means of atomistic off-lattice Monte Carlo simulations in the semi-grand canonical ensemble using classical interatomic potentials. The SRO parameter defined by Cowley [Phys. Rev. B 77, 669 (1950)] is used to quantify the degree of ordering. In agreement with experiments a strong ordering tendency in the Cr distribution at low Cr concentrations (~< 5%) is observed, as manifested in negative values of the SRO parameters. For intermediate Cr concentrations (5% ~< c_Cr ~< 15%) the SRO parameter for the alpha-phase goes through a minimum, but at the solubility limit the alpha-phase still displays a rather strong SRO. In thermodynamic equilibrium for concentrations within the two-phase region the SRO parameter measured over the entire sample therefore comprises the contributions from both the alpha and alpha-prime phases. If both of these contributions are taken into account, it is possible to quantitatively reproduce the experimental results and interpret their physical implications. It is thereby shown that the inversion of the SRO observed experimentally is due to the formation of stable (supercritical) alpha-prime precipitates. It is not related to the loss of SRO in the alpha-phase or to the presence of unstable (subcritical) Cr precipitates in the alpha-phase.Comment: 9 pages, 8 figure

Random template placement and prior information

In signal detection problems, one is usually faced with the task of searching a parameter space for peaks in the likelihood function which indicate the presence of a signal. Random searches have proven to be very efficient as well as easy to implement, compared e.g. to searches along regular grids in parameter space. Knowledge of the parameterised shape of the signal searched for adds structure to the parameter space, i.e., there are usually regions requiring to be densely searched while in other regions a coarser search is sufficient. On the other hand, prior information identifies the regions in which a search will actually be promising or may likely be in vain. Defining specific figures of merit allows one to combine both template metric and prior distribution and devise optimal sampling schemes over the parameter space. We show an example related to the gravitational wave signal from a binary inspiral event. Here the template metric and prior information are particularly contradictory, since signals from low-mass systems tolerate the least mismatch in parameter space while high-mass systems are far more likely, as they imply a greater signal-to-noise ratio (SNR) and hence are detectable to greater distances. The derived sampling strategy is implemented in a Markov chain Monte Carlo (MCMC) algorithm where it improves convergence.Comment: Proceedings of the 8th Edoardo Amaldi Conference on Gravitational Waves. 7 pages, 4 figure

Cosmic Swarms: A search for Supermassive Black Holes in the LISA data stream with a Hybrid Evolutionary Algorithm

We describe a hybrid evolutionary algorithm that can simultaneously search for multiple supermassive black hole binary (SMBHB) inspirals in LISA data. The algorithm mixes evolutionary computation, Metropolis-Hastings methods and Nested Sampling. The inspiral of SMBHBs presents an interesting problem for gravitational wave data analysis since, due to the LISA response function, the sources have a bi-modal sky solution. We show here that it is possible not only to detect multiple SMBHBs in the data stream, but also to investigate simultaneously all the various modes of the global solution. In all cases, the algorithm returns parameter determinations within $5\sigma$ (as estimated from the Fisher Matrix) of the true answer, for both the actual and antipodal sky solutions.Comment: submitted to Classical & Quantum Gravity. 19 pages, 4 figure

АКТУАЛЬНІСТЬ СИМУЛЯЦІЙНИХ МЕТОДІВ НАВЧАННЯ НА ЕТАПІ ПІСЛЯДИПЛОМНОЇ ОСВІТИ ВИПУСКНИКІВ ВИЩИХ МЕДИЧНИХ НАВЧАЛЬНИХ ЗАКЛАДІВ

According to modern world trends and the demand of domestic medicine, training in simulation centers is an appropriate way for students to learn practical skills from the first year, as well as medical practitioners. The aim – to determine the level of competence of graduates of higher medical educational institutions in possession of a list of practical skills. Material and Methods. A survey was conducted on the Royal College of General Practitioners knowledge assessment scale in two groups of interns of the first year of study, majoring in General Practice – Family Medicine, before and after the practical training in the simulation center. Group 1 included interns who, upon receiving education, did not have practical medical experience outside the institution of higher education (n = 86); group 2 (n = 16) – interns who worked during their studies in healthcare institutions as paramedical workers. Results. As a result of the analysis of the data obtained, it was found that interns of the group 1 rated their level of possession of practical skills as requiring improvement. Interns who, when receiving education in medical higher educational institutions, worked in healthcare institutions, had a significantly higher level of proficiency in practical skills related to the competence of paramedical personnel. Conclusions. Trainings on the level of mastering of practical skills and abilities when applying simulation training methods are highly effective, which is proved by the results of our research.Согласно современным мировым тенденциям и запросу отечественной медицины, целесообразным способом овладения практическими навыками как студентами, начиная с первого курса, так и врачами-практиками, являются тренинги в симуляционных центрах. Цель – определение уровня компетентности выпускников высших медицинских учебных заведений по владению перечнем практических навыков и умений. Материал и методы. Проведено анкетирование по шкале оценки знаний Королевского колледжа врачей общей практики в двух группах врачей-интернов первого года обучения по специальности «Общая практика – семейная медицина» до и после практического занятия в симуляционном центре. В 1 группу вошли врачи-интерны, которые при получении образования не имели практического медицинского опыта за пределами высшего учебного заведения (n=86); во 2 группу (n=16) – врачи-интерны, которые во время учебы работали в учреждениях здравоохранения на должностях средних медицинских работников. Результаты. В результате анализа полученных данных было установлено, что врачи-интерны 1 группы оценили свой уровень владения практическими навыками как требующий повышения. Врачи-интерны, которые при получении образования в медицинских высших учебных заведениях работали в учреждениях здравоохранения, имели достоверно более высокий уровень показателей владения практическими навыками, относящимися к компетенции среднего медицинского персонала. Выводы. Тренинги по уровню овладения практическими навыками и умениями при применении симуляционных методов обучения являются высокоэффективными, что доказывают результаты наших исследований.Згідно із сучасними світовими тенденціями та запитом вітчизняної медицини, найдоцільнішим способом оволодіння практичними навичками як студентами, починаючи з першого курсу, так і лікарями-практиками, є тренінги у симуляційних центрах. Мета – визначення рівня компетентності випускників вищих медичних навчальних закладів щодо володіння переліком практичних навичок та умінь. Матеріал і методи. Проведено анкетування за шкалою оцінки знань Королівського коледжу лікарів загальної практики у двох групах лікарів-інтернів першого року навчання зі спеціальності «Загальна практика – сімейна медицина» до та після практичного заняття у симуляційному центрі. До 1 групи увійшли лікарі-інтерни, які під час отримання освіти не мали практичного медичного досвіду за межами вищого навчального закладу (n=86); до 2&nbsp;групи (n=16) – лікарі-інтерни, які під час навчання працювали у закладах охорони здоров’я на посадах середніх медичних працівників. Результати. У результаті аналізу отриманих даних було встановлено, що лікарі-інтерни 1 групи оцінили свій рівень володіння практичними навичками, як такий, що потребує підвищення. Лікарі-інтерни, які під час отримання освіти у медичних вищих навчальних закладах працювали у закладах охорони здоров’я, мали достовірно вищий рівень показників володіння практичними навичками, що належать до компетенції середнього медичного персоналу. Висновки. Тренінги щодо рівня оволодіння практичними навичками та уміннями при застосуванні симуляційних методів навчання є високоефективними, що доводять результати наших досліджень

LISA as a dark energy probe

Recently it was shown that the inclusion of higher signal harmonics in the inspiral signals of binary supermassive black holes (SMBH) leads to dramatic improvements in parameter estimation with the Laser Interferometer Space Antenna (LISA). In particular, the angular resolution becomes good enough to identify the host galaxy or galaxy cluster, in which case the redshift can be determined by electromagnetic means. The gravitational wave signal also provides the luminosity distance with high accuracy, and the relationship between this and the redshift depends sensitively on the cosmological parameters, such as the equation-of-state parameter $w=p_{\rm DE}/\rho_{\rm DE}$ of dark energy. With a single binary SMBH event at $z < 1$ having appropriate masses and orientation, one would be able to constrain $w$ to within a few percent. We show that, if the measured sky location is folded into the error analysis, the uncertainty on $w$ goes down by an additional factor of 2-3, leaving weak lensing as the only limiting factor in using LISA as a dark energy probe.Comment: 11pages, 1 Table, minor changes in text, accepted for publication in Classical and Quantum Gravity (special issue for proceedings of 7th LISA symposium

Innovation activity of scientists as a factor in the development of academic entrepreneurship in Russia

The development of academic entrepreneurship as a way of transfer of innovation is an urgent task. One of the main factors in the development of academic entrepreneurship is innovation-oriented staff of higher education institutions. Insufficient attention of the scientific literature to importance of this factor is thwarting progress of various forms of academic entrepreneurship. In connection with this proposed study is aimed at determining the degree of scientific innovation activity influence on the development of academic entrepreneurship in Russia. Academic entrepreneurship in Russia has been chosen as the object of study. Analysis of the basic research in the field of academic entrepreneurship for the period of 2011-2016 years was used to achieve this goal. Analysis of publications was revealed that the innovative activity of the teaching staff of universities is a critical factor in the development of academic entrepreneurship. However, Russian scientists are characterized by low innovation activity, resulting in academic entrepreneurship in Russia is weak. The researchers suggest the following solutions to eliminate or minimize the effects of this problem: full awareness and moral training of the scientists involved in the innovation process of higher education institutions; profit payment; creating a psychological climate that will affect the scientific process of self-realization; continuous training of employees involved in the innovation process of higher education institutions; the creation of conditions that will contribute to the manifestation of creative activity of scientists; provide greater confidence to young scientists, graduate students and undergraduates; providing moral and material encouragement of initiatives, experimentation and creativity of scientific and pedagogical staff; the allocation of free time for scientists to research and search activities and others. The data obtained can be used by the guidance of Russian universities to enhance innovation activity of the teaching staff of universities

Universally Coupled Massive Gravity

We derive Einstein's equations from a linear theory in flat space-time using free-field gauge invariance and universal coupling. The gravitational potential can be either covariant or contravariant and of almost any density weight. We adapt these results to yield universally coupled massive variants of Einstein's equations, yielding two one-parameter families of distinct theories with spin 2 and spin 0. The Freund-Maheshwari-Schonberg theory is therefore not the unique universally coupled massive generalization of Einstein's theory, although it is privileged in some respects. The theories we derive are a subset of those found by Ogievetsky and Polubarinov by other means. The question of positive energy, which continues to be discussed, might be addressed numerically in spherical symmetry. We briefly comment on the issue of causality with two observable metrics and the need for gauge freedom and address some criticisms by Padmanabhan of field derivations of Einstein-like equations along the way.Comment: Introduction notes resemblance between Einstein's discovery process and later field/spin 2 project; matches journal versio

Study of Foaming Properties and Effect of the Isomeric Distribution of Some Anionic Surfactants

Using different reaction conditions of photosulfochlorination of n-dodecane, two samples of anionic surfactants of sulfonate type are obtained. Their micellar behavior has been already reported and the relationship between their isomeric distribution and their chemical structures and micellar behaviors have been more thoroughly explored. In this investigation, we screened the foaming properties (foaming power and foam stability) by a standardized method very similar to the Ross–Miles foaming tests to identify which surfactants are suitable for applications requiring high foaming, or, alternatively, low foaming. The results obtained for the synthesized surfactants are compared to those obtained for an industrial sample of secondary alkanesulfonate (Hostapur 60) and to those of a commercial sample of sodium dodecylsulfate used as reference for anionic surfactants. The foam formation and foam stability of aqueous solutions of the two samples of dodecanesulfonate are compared as a function of their isomeric distribution. These compounds show good foaming power characterized in most cases by metastable or dry foams. The highest foaming power is obtained for the sample rich in primary isomers which also produces foam with a relatively high stability. For the sample rich in secondary isomers we observe under fixed conditions a comparable initial foam height but the foam stability turns out to be low. This property is interesting for applications requiring low foaming properties such as dishwashing liquid for machines. The best results are observed near and above the critical micellar concentrations and at 25 C for both the samples

Binary black hole spectroscopy

We study parameter estimation with post-Newtonian (PN) gravitational waveforms for the quasi-circular, adiabatic inspiral of spinning binary compact objects. The performance of amplitude-corrected waveforms is compared with that of the more commonly used restricted waveforms, in Advanced LIGO and EGO. With restricted waveforms, the properties of the source can only be extracted from the phasing. For amplitude-corrected waveforms, the spectrum encodes a wealth of additional information, which leads to dramatic improvements in parameter estimation. At distances of $\sim 100$ Mpc, the full PN waveforms allow for high-accuracy parameter extraction for total mass up to several hundred solar masses, while with the restricted ones the errors are steep functions of mass, and accurate parameter estimation is only possible for relatively light stellar mass binaries. At the low-mass end, the inclusion of amplitude corrections reduces the error on the time of coalescence by an order of magnitude in Advanced LIGO and a factor of 5 in EGO compared to the restricted waveforms; at higher masses these differences are much larger. The individual component masses, which are very poorly determined with restricted waveforms, become measurable with high accuracy if amplitude-corrected waveforms are used, with errors as low as a few percent in Advanced LIGO and a few tenths of a percent in EGO. The usual spin-orbit parameter $\beta$ is also poorly determined with restricted waveforms (except for low-mass systems in EGO), but the full waveforms give errors that are small compared to the largest possible value consistent with the Kerr bound. This suggests a way of finding out if one or both of the component objects violate this bound. We also briefly discuss the effect of amplitude corrections on parameter estimation in Initial LIGO.Comment: 28 pages, many figures. Final version accepted by CQG. More in-depth treatment of component mass errors and detectability of Kerr bound violations; improved presentatio

A template bank for gravitational waveforms from coalescing binary black holes: non-spinning binaries

Gravitational waveforms from the inspiral and ring-down stages of the binary black hole coalescences can be modelled accurately by approximation/perturbation techniques in general relativity. Recent progress in numerical relativity has enabled us to model also the non-perturbative merger phase of the binary black-hole coalescence problem. This enables us to \emph{coherently} search for all three stages of the coalescence of non-spinning binary black holes using a single template bank. Taking our motivation from these results, we propose a family of template waveforms which can model the inspiral, merger, and ring-down stages of the coalescence of non-spinning binary black holes that follow quasi-circular inspiral. This two-dimensional template family is explicitly parametrized by the physical parameters of the binary. We show that the template family is not only \emph{effectual} in detecting the signals from black hole coalescences, but also \emph{faithful} in estimating the parameters of the binary. We compare the sensitivity of a search (in the context of different ground-based interferometers) using all three stages of the black hole coalescence with other template-based searches which look for individual stages separately. We find that the proposed search is significantly more sensitive than other template-based searches for a substantial mass-range, potentially bringing about remarkable improvement in the event-rate of ground-based interferometers. As part of this work, we also prescribe a general procedure to construct interpolated template banks using non-spinning black hole waveforms produced by numerical relativity.Comment: A typo fixed in Eq.(B11