1,432 results on '"Ivanova N"'
Search Results
2. Russian soft power in the Baltic States through the lens of research: traditions, competition, confrontation
- Author
-
Vorotnikov V. V. and Ivanova N. A.
- Subjects
soft power ,effect of soft power ,russian foreign policy ,baltic states ,estonia ,latvia ,lithuania ,Regional economics. Space in economics ,HT388 - Abstract
In this article, we aim to analyse the research discourse in the Baltic countries (Estonia, Latvia, and Lithuania) as regards Russian soft power, which is considered as hard power, and to compare the theses that dominate this discourse with the actual interactions between Russia and the three states in media, education, and culture. Each Baltic country has built a system of political and legal restrictions to diminish the effect of Russian soft power, which is considered in terms of hard power, i.e. as a threat to national security. The current forms of Russian soft power are becoming less productive in the region and their use in the negative political context of bilateral relations has the opposite effect for Russia — the country loses in reputation and image. The main factor at play is the information content of the Russian-language media space. At odds with the historical and political views of a significant part of the Baltic States’ ruling class, it is becoming the target of counteraction. At the same time, Russian high and mass culture and, partly, educational services are in demand from both Baltic Russian speakers and ethnic Lithuanians, Latvians, and Estonians. Our analysis shows that the views of Baltic researchers that Russian soft power is politics-driven and foreign to the region are exaggerated and biased. In its turn, Russian soft power in the Baltics retains the potential to aid the country’s foreign policy, being a complement to the latter rather than its direct tool.
- Published
- 2019
- Full Text
- View/download PDF
3. Isocitrate dehydrogenase 1 mutation is associated with reduced levels of inflammation in glioma patients
- Author
-
Auezova R, Ivanova N, Akshulakov S, Zhetpisbaev B, Kozhakhmetova A, Ryskeldiyev N, Mustafin K, Teltayev D, and Auezova L
- Subjects
glioma ,IDH ,inflammation ,neutrophil–lymphocyte ratio ,survival ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Raushan Auezova,1 Natalia Ivanova,2 Serik Akshulakov,1 Berik Zhetpisbaev,1 Aizhan Kozhakhmetova,1 Nurzhan Ryskeldiyev,1 Khalit Mustafin,1 Daniyar Teltayev,1 Lizette Auezova31Department of Pathology of the Central Nervous System, National Center for Neurosurgery, Astana, Kazakhstan; 2Scientific Department, Polenov Russian Scientific Research Institute of Neurosurgery (a branch of Federal Almazov North-West Medical Research Center), Ministry of Health of the Russian Federation, Saint-Petersburg, Russia; 3Bioactive Molecules Research Group, Department of Chemistry and Biochemistry, Faculty of Sciences-II, Lebanese University, Beirut, LebanonBackground: Glioma patients with mutant isocitrate dehydrogenase have improved survival; this could be in part due to the suppressive effect of mutant IDH on the level of chronic inflammation. This study aimed to prospectively analyze the association of IDH1 mutation status with preoperative levels of blood inflammatory markers: neutrophil–lymphocyte ratio (NLR), platelet–lymphocyte ratio (PLR), C-reactive protein (CRP), and red cell distribution width (RDW) in gliomas.Patients and methods: Receiver operating characteristic curves for cutoff value determination, various bivariate tests, and survival analyses (Kaplan–Meier curves and Cox regression) were performed.Results: Patients with mutant IDH1 had reduced levels of NLR (P
- Published
- 2019
4. Assessment of Changes in Chernobyl Contamination and Erosion Rates for Arable Soils Using Resampling Method
- Author
-
Ivanov, M. M., Ivanova, N. N., Golosov, V. N., Usacheva, A. A., Smolina, G. A., and Fomicheva, D. V.
- Published
- 2024
- Full Text
- View/download PDF
5. Degenerations of 3-dimensional nilpotent associative algebras over an algebraically closed field
- Author
-
Ivanova, N. M. and Pallikaros, C. A.
- Subjects
Mathematics - Rings and Algebras ,14R20, 14D06 - Abstract
We determine the complete degeneration picture inside the variety of nilpotent associative algebras of dimension 3 over an algebraically closed field of characteristic not equal to 2. Comparing with the discussion in [Ivanova N.M. and Pallikaros C.A., Degenerations of complex associative algebras of dimension three via Lie and Jordan algebras, {\it Advances in Group Theory and Applications}, 18 (2024), 41-79], for some of the arguments in the present article we needed to develop alternative techniques which are now valid over an arbitrary algebraically closed field. There is a dichotomy of cases concerning the results obtained, corresponding to whether the characteristic of the field is 2 or not., Comment: In this new version the case where the field has characteristic equal to two is also discussed
- Published
- 2023
6. Association of preoperative levels of selected blood inflammatory markers with prognosis in gliomas
- Author
-
Auezova R, Ryskeldiev N, Doskaliyev A, Kuanyshev Y, Zhetpisbaev B, Aldiyarova N, Ivanova N, Akshulakov S, and Auezova L
- Subjects
glioma ,neutrophil–lymphocyte ratio ,platelet ,red cell distribution width ,survival ,tumour grade ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Raushan Auezova,1 Nurzhan Ryskeldiev,1 Aidos Doskaliyev,1 Yerbol Kuanyshev,1 Berik Zhetpisbaev,1 Nurgul Aldiyarova,1 Natalia Ivanova,2 Serik Akshulakov,1 Lizette Auezova3 1Department of Pathology of the Central Nervous System, National Centre for Neurosurgery, Astana, Kazakhstan; 2Polenov Russian Scientific Research Institute of Neurosurgery (a branch of Federal Almazov North-West Medical Research Centre), Ministry of Health of the Russian Federation, Saint-Petersburg, Russia; 3Bioactive Molecules Research Group, Department of Chemistry and Biochemistry, Faculty of Sciences-II, Lebanese University, Beirut, Lebanon Background: Red cell distribution width (RDW), neutrophil–lymphocyte ratio (NLR), and platelet count (PLT) routinely tested as part of the complete blood count are indicative of systemic inflammation. The prognostic significance of NLR and PLT in cancer was demonstrated in many studies while the role of RDW has been hardly investigated. The present study aimed to assess the association of RDW, NLR, and PLT with survival and tumor grade in glioma patients. Methods: Clinical data from 178 patients with primary gliomas treated in a single institution were retrospectively analyzed. Receiver operating characteristic curves for cutoff value determination, Kaplan–Meier survival analysis, various bivariate tests, and univariate and multivariate Cox regression analyses were performed. Results: Patients with high RDW (≥13.95) and NLR (≥4) levels had worse overall survival (OS) (Wilcoxon test, P
- Published
- 2016
7. PUBLIC DIPLOMACY AS AN EFFECTIVE MECHANISM OF THE FOREIGN POLICY OF THE STATE
- Author
-
Ivanova N.
- Subjects
Political science (General) ,JA1-92 - Published
- 2018
8. Degenerations of complex associative algebras of dimension three via Lie and Jordan algebras
- Author
-
Ivanova, N. M. and Pallikaros, C. A.
- Subjects
Mathematics - Rings and Algebras - Abstract
Let $\boldsymbol\Lambda_3(\mathbb C)\,(=\mathbb C^{27})$ be the space of structure vectors of $3$-dimensional algebras over $\mathbb C$ considered as a $G$-module via the action of $G={\rm GL}(3,\mathbb C)$ on $\boldsymbol\Lambda_3(\mathbb C)$ `by change of basis'. We determine the complete degeneration picture inside the algebraic subset $\mathcal A^s_3$ of $\boldsymbol\Lambda_3(\mathbb C)$ consisting of associative algebra structures via the corresponding information on the algebraic subsets $\mathcal L_3$ and $\mathcal J_3$ of $\boldsymbol\Lambda_3(\mathbb C)$ of Lie and Jordan algebra structures respectively. This is achieved with the help of certain $G$-module endomorphisms $\phi_1$, $\phi_2$ of $\boldsymbol\Lambda_3(\mathbb C)$ which map $\mathcal A^s_3$ onto algebraic subsets of $\mathcal L_3$ and $\mathcal J_3$ respectively.
- Published
- 2022
9. Phase composition and crystallinity degree of nanostructured products of anode oxidation of manganese(II) ions doped by ions of lithium and cobalt(II)
- Author
-
Sokolsky G., Ivanova N., Ivanov S., Tomila T., and Boldyrev Ye.
- Subjects
Mn ,Li ,Co ,nanostructures ,phase composition ,Chemical technology ,TP1-1185 - Abstract
The influence of dopant ions on the phase composition and structure ordering of electrodeposited nanoxides of manganese was investigated. Additives of dopant ions of Li and Co(II) and fluorine-containing electrolytes have been applied for preparation of samples by anode electrodeposition. The samples have been studied by methods of chemical analysis, XRD, TEM, Fourier spectroscopy etc. TEM observation showed that the presence of dopant ions of lithium and cobalt in electrolyte decreased crystallinity of samples, influenced the length and perfection of nanorods, and made structure more defective. The diametres of the nanorods ranged from 10 to 20 nm.
- Published
- 2007
- Full Text
- View/download PDF
10. Nonuniform heating of a substrate in evaporative lithography
- Author
-
Al-Muzaiqer, M. A., Kolegov, K. S., Ivanova, N. A., and Fliagin, V. M.
- Subjects
Condensed Matter - Soft Condensed Matter ,Physics - Fluid Dynamics - Abstract
This work is devoted to a method to generate particle cluster assemblies, and connected to evaporative lithography. Experiments are carried out using nonuniform evaporation of an isopropanol film containing polystyrene microspheres in a cylindrical cell. The local inhomogeneity of the vapor flux density is achieved by exploiting the temperature gradient. A copper rod is mounted in the central part of the bottom of the cell for further heating. The thermocapillary flow resulting from the surface tension gradient, due in turn to the temperature drop, transfers the particles that were originally at rest at the bottom of the cell. The effect of the initial thickness of the liquid layer on the height and base area of the cluster formed in the central region of the cell is studied. The velocity is measured using particle image velocimetry. A model describing the initial stage of the process is developed. The equations of heat transfer and thermal conductivity are used to define the temperature distribution in the liquid and in the cell. The fluid flow is simulated using the lubrication approximation. The particle distribution is modeled using the convection-diffusion equation. The evaporation flux density is calculated using the Hertz-Knudsen equation. The dependence of the liquid viscosity on the particle concentration is described by Mooney's formula. Numerical results show that the liquid film gradually becomes thinner in the central region, as the surface tension decreases with the increasing temperature. The liquid flow is directed to the heater near the substrate, and it transfers the particles to the center of the cell. The volume fraction of the particles increases over time in this region. The heat flow from the heater affects the geometry of the cluster for two reasons: first, the Marangoni flow velocity depends on the temperature gradient, and second, the decrease ...
- Published
- 2021
- Full Text
- View/download PDF
11. Express Analysis of Vertical Distribution of 137Cs to Assess the Rates of Erosion and Accumulation Processes in the Zone of Intense Radioactive Contamination
- Author
-
Ivanov, M. M. and Ivanova, N. N.
- Published
- 2023
- Full Text
- View/download PDF
12. The X-ray Emissivity of Low-Density Stellar Populations
- Author
-
Heinke, C. O., Ivanov, M. G., Koch, E. W., Andrews, R., Chomiuk, L., Cohn, H. N., Crothers, S., de Boer, T., Ivanova, N., Kong, A. K. H., Leigh, N. W. C., Lugger, P. M., Nelson, L., Parr, C. J., Rosolowsky, E. W., Ruiter, A. J., Sarazin, C. L., Shaw, A. W., Sivakoff, G. R., and Berg, M. van den
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies - Abstract
The dynamical production of low-mass X-ray binaries and brighter cataclysmic variables (CVs) in dense globular clusters is well-established. We investigate how the X-ray emissivity of fainter X-ray binaries (principally CVs and coronally active binaries) varies between different environments. We compile calculations (largely from the literature) of the X-ray emissivity of old stellar populations, including open and globular clusters and several galaxies. We investigate three literature claims of unusual X-ray sources in low-density stellar populations. We show that a suggested quiescent neutron star in the open cluster NGC 6819 is a foreground M dwarf. We show that the suggested diffuse X-ray emission from an old nova shell in the globular cluster NGC 6366 is actually a background galaxy cluster. And we show that a suggested population of quiescent X-ray binaries in the Sculptor Dwarf Galaxy is mostly (perhaps entirely) background galaxies. We find that above densities of $10^4$ M$_{\odot}$/pc$^3$, the X-ray emissivity of globular clusters increases, due to dynamical production of X-ray emitting systems. Below this density, globular clusters have lower X-ray emissivity than the other populations, and we do not see a strong dependence of X-ray emissivity due to density effects. We find significant correlations between X-ray emissivity and binary fraction, metallicity, and density. Sampling these fits via bootstrap techniques gives less significant correlations, but confirms the effect of metallicity on low-density populations, and that of density on the full globular cluster sample., Comment: 28 pages, 23 figures. MNRAS, in press
- Published
- 2020
- Full Text
- View/download PDF
13. Evolving LMXBs: CARB Magnetic Braking
- Author
-
Van, K. X. and Ivanova, N.
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
The formation of low-mass X-ray binaries (LMXBs) is an ongoing challenge in stellar evolution. The important subset of LMXBs are the binary systems with a neutron star (NS) accretor. In NS LMXBs with non-degenerate donors, the mass transfer is mainly driven by magnetic braking. The discrepancies between the observed mass transfer (MT) rates and the theoretical models were known for a while. Theory predictions of the MT rates are too weak and differ by an order of magnitude or more. Recently, we showed that with the standard magnetic braking, it is not possible to find progenitor binary systems such that they could reproduce -- at any time of their evolution -- most of the observed persistent NS LMXBs. In this ${\it Letter}$ we present a modified magnetic braking prescription, CARB (Convection And Rotation Boosted). CARB magnetic braking combines two recent improvements in understanding stellar magnetic fields and magnetized winds -- the dependence of the magnetic field strength on the outer convective zone and the dependence of the Alfv\`en radius on the donor's rotation. Using this new magnetic braking prescription, we can reproduce the observed mass transfer rates at the detected mass ratio and orbital period for all well-observed to-the-date Galactic persistent NS LMXBs. For the systems where the effective temperature of the donor stars is known, theory agrees with observations as well., Comment: 7 pages, 3 figures, 1 table. Published in Astrophysical Journal Letters, Volume 886, Issue 2, article id. L31, 5 pp. (2019). The typo in the equation 5 is fixed in this version. No results presented here are affected. All follow-up papers used the correct version of the equation (without the typo)
- Published
- 2019
- Full Text
- View/download PDF
14. Field Verification of Erosion Models Based on the Studies of a Small Catchment in the Vorobzha River Basin (Kursk oblast, Russia)
- Author
-
Golosov, V. N., Zhidkin, A. P., Petel’ko, A. I., Osipova, M. S., Ivanova, N. N., and Ivanov, M. M.
- Published
- 2022
- Full Text
- View/download PDF
15. Low Mass X-ray Binaries: The Effects of the Magnetic Braking Prescription
- Author
-
Van, K. X., Ivanova, N., and Heinke, C. O.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present a population study of low- and intermediate-mass X-ray binaries (LMXBs) with neutron star accretors, performed using the detailed 1D stellar evolution code MESA. We identify all plausible Roche-lobe overflowing binaries at the start of mass transfer, and compare our theoretical mass transfer tracks to the population of well-studied Milky Way LMXBs. The mass transferring evolution depends on the accepted magnetic braking (MB) law for angular momentum loss. The most common MB prescription ("Skumanich MB") originated from observations of the time-dependence of rotational braking of Sun-type stars, where the angular momentum loss rate depends on the donor mass $M_d$, donor radius $R_d$, and rotation rate $\Omega$, $\dot{J} \propto M_d R_d^{\gamma} \Omega^3$. The functional form of the Skumanich MB can be also obtained theoretically assuming a radial magnetic field, isotropic isothermal winds, and boosting of the magnetic field by rotation. Here we show that this simple form of the Skumanich MB law gives mass transfer rates an order of magnitude too weak to explain most observed persistent LMXBs. This failure suggests that the standard Skumanich MB law should not be employed to interpret Galactic, or extragalactic, LMXB populations, with either detailed stellar codes or rapid binary population synthesis codes. We investigate modifications for the MB law, and find that including a scaling of the magnetic field strength with the convective turnover time, and a scaling of MB with the wind mass loss rate, can reproduce persistent LMXBs, and does a better job at reproducing transient LMXBs., Comment: 20 pages, 10 figures, accepted to MNRAS
- Published
- 2018
- Full Text
- View/download PDF
16. Long-term outcomes of uterine artery embolization in patients with early hypotonic postpartum hemorrhage
- Author
-
Konoplev, B. A., primary, Breslav, I. Yu., additional, Kurtser, М. A., additional, Konopliannikov, А. G., additional, Grigoryan, A. M., additional, Oreshkova, I. A., additional, and Ivanova, N. Yu., additional
- Published
- 2024
- Full Text
- View/download PDF
17. Describing certain Lie algebra orbits via polynomial equations
- Author
-
Ivanova, N. M. and Pallikaros, C. A.
- Subjects
Mathematical Physics - Abstract
Let $\mathfrak{h}_3$ be the Heisenberg algebra and let $\mathfrak g$ be the 3-dimensional Lie algebra having $[e_1,e_2]=e_1\,(=-[e_2,e_1])$ as its only non-zero commutation relations. We describe the closure of the orbit of a vector of structure constants corresponding to $\mathfrak{h}_3$ and $\mathfrak g$ respectively as an algebraic set giving in each case a set of polynomials for which the orbit closure is the set of common zeros. Working over an arbitrary infinite field, this description enables us to give an alternative way, using the definition of an irreducible algebraic set, of obtaining all degenerations of $\mathfrak{h}_3$ and $\mathfrak g$ (the degeneration from $\mathfrak g$ to $\mathfrak{h}_3$ being one of them).
- Published
- 2017
18. New Cataclysmic Variables and other Exotic Binaries in the Globular Cluster 47 Tucanae
- Author
-
Sandoval, L. E. Rivera, Berg, M. van den, Heinke, C. O., Cohn, H. N., Lugger, P. M., Anderson, J., Cool, A. M., Edmonds, P. D., Wijnands, R., Ivanova, N., and Grindlay, J. E.
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present 22 new (+3 confirmed) cataclysmic variables (CVs) in the non core-collapsed globular cluster 47 Tucanae (47 Tuc). The total number of CVs in the cluster is now 43, the largest sample in any globular cluster so far. For the identifications we used near-ultraviolet (NUV) and optical images from the Hubble Space Telescope, in combination with X-ray results from the Chandra X-ray Observatory. This allowed us to build the deepest NUV CV luminosity function of the cluster to date. We found that the CVs in 47 Tuc are more concentrated towards the cluster center than the main sequence turnoff stars. We compared our results to the CV populations of the core-collapsed globular clusters NGC 6397 and NGC 6752. We found that 47 Tuc has fewer bright CVs per unit mass than those two other clusters. That suggests that dynamical interactions in core-collapsed clusters play a major role creating new CVs. In 47 Tuc, the CV population is probably dominated by primordial and old dynamically formed systems. We estimated that the CVs in 47 Tuc have total masses of approx. 1.4 M_sun. We also found that the X-ray luminosity function of the CVs in the three clusters is bimodal. Additionally, we discuss a possible double degenerate system and an intriguing/unclassified object. Finally, we present four systems that could be millisecond pulsar companions given their X-ray and NUV/optical colors. For one of them we present very strong evidence for being an ablated companion. The other three could be CO- or He-WDs., Comment: Published on MNRAS. 31 Pages, 23 Figures, 5 Tables. Minor changes with respect to previous arXiv version
- Published
- 2017
- Full Text
- View/download PDF
19. On degenerations of algebras over an arbitrary field
- Author
-
Ivanova, N. M. and Pallikaros, C. A.
- Subjects
Mathematics - Rings and Algebras - Abstract
For each $n\ge2$ we classify all $n$-dimensional algebras over an arbitrary infinite field which have the property that the $n$-dimensional abelian Lie algebra is their only proper degeneration., Comment: We now complete the classification of all 'level one' algebras over an arbitrary field. Some new references have been added
- Published
- 2017
20. Cold start of proton exchange membrane fuel cell using build-in catalytic heater
- Author
-
Ivanova, N A, primary, Baranov, I E, additional, Kalinnikov, A A, additional, Mensharapov, R M, additional, Spasov, D D, additional, Sinyakov, M V, additional, Nikolaev, I I, additional, Ostrovsky, S V, additional, Grigoriev, S A, additional, and Fateev, V N, additional
- Published
- 2024
- Full Text
- View/download PDF
21. Assessment of the Time Characteristics of Walking Techniques Using a Mobile Information and Measurement System
- Author
-
Alekseev, V. V., Ivanova, N. E., Ivanov, A. Yu., Korolev, P. G., Sokolova, F. M., and Tsareva, A. V.
- Published
- 2021
- Full Text
- View/download PDF
22. Stability of mass transfer from massive giants: double black-hole binary formation and ultra-luminous X-ray sources
- Author
-
Pavlovskii, K., Ivanova, N., Belczynski, K., and Van, K. X.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
The mass transfer in binaries with massive donors and compact companions, when the donors rapidly evolve after their main sequence, is one of the dominant formation channels of merging double stellar-mass black hole binaries. This mass transfer was previously postulated to be unstable and was expected to lead to a common envelope event. The common envelope event then would end with either double black hole formation, or with the merger of the two stars. We re-visit the stability of this mass transfer, and find that for a large range of the binary orbital separations this mass transfer is stable. This newly found stability allows us to reconcile the theoretical rate for double black hole binary mergers predicted by population synthesis studies, and the empirical rate obtained by LIGO. Futhermore, the stability of the mass transfer leads to the formation of ultra-luminous X-ray sources. The theoretically predicted formation rates of ultra-luminous X-ray sources powered by a stellar-mass BH, as well as the range of produced X-ray luminosity, can explain the observed bright ultra-luminous X-ray sources., Comment: 10 pages,3 figures, 1 table, submitted to MNRAS
- Published
- 2016
- Full Text
- View/download PDF
23. Mass transfer and magnetic braking in Sco X-1
- Author
-
Pavlovskii, K. and Ivanova, N.
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
Sco X-1 is a low-mass X-ray binary (LMXB) that has one of the most precisely determined set of binary parameters such as the mass accretion rate, companions mass ratio and the orbital period. For this system, as well as for a large fraction of other well-studied LMXBs, the observationally-inferred mass accretion rate is known to strongly exceed the theoretically expected mass transfer rate. We suggest that this discrepancy can be solved by applying a modified magnetic braking prescription, which accounts for increased wind mass loss in evolved stars compared to main sequence stars. Using our mass transfer framework based on {\tt MESA}, we explore a large range of binaries at the onset of the mass transfer. We identify the subset of binaries for which the mass transfer tracks cross the Sco X-1 values for the mass ratio and the orbital period. We confirm that no solution can be found for which the standard magnetic braking can provide the observed accretion rates, while wind-boosted magnetic braking can provide the observed accretion rates for many progenitor binaries that evolve to the observed orbital period and mass ratio., Comment: Accepted to MNRAS
- Published
- 2015
- Full Text
- View/download PDF
24. Discovery of near-ultraviolet counterparts to millisecond pulsars in the globular cluster 47 Tucanae
- Author
-
Rivera-Sandoval, L. E., Berg, M. van den, Heinke, C. O., Cohn, H. N., Lugger, P. M., Freire, P., Anderson, J., Serenelli, A. M., Althaus, L. G., Cool, A. M., Grindlay, J. E., Edmonds, P. D., Wijnands, R., and Ivanova, N.
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report the discovery of the likely white dwarf companions to radio millisecond pulsars 47 Tuc Q and 47 Tuc S in the globular cluster 47 Tucanae. These blue stars were found in near-ultraviolet images from the Hubble Space Telescope for which we derived accurate absolute astrometry, and are located at positions consistent with the radio coordinates to within 0.016 arcsec (0.2sigma). We present near-ultraviolet and optical colours for the previously identified companion to millisecond pulsar 47 Tuc U, and we unambiguously confirm the tentative prior identifications of the optical counterparts to 47 Tuc T and 47 Tuc Y. For the latter, we present its radio-timing solution for the first time. We find that all five near-ultraviolet counterparts have U300-B390 colours that are consistent with He white dwarf cooling models for masses ~0.16-0.3 Msun and cooling ages within ~0.1-6 Gyr. The Ha-R625 colours of 47 Tuc U and 47 Tuc T indicate the presence of a strong Ha absorption line, as expected for white dwarfs with an H envelope., Comment: Accepted for publication on MNRAS. 12 pages, 5 figures, 3 tables
- Published
- 2015
- Full Text
- View/download PDF
25. Uniaxial anisotropy and low-temperature antiferromagnetism of Mn2BO4 single crystal
- Author
-
Kazak, N. V., Platunov, M. S., Knyazev, Yu. V., Ivanova, N. B., Bayukov, O. A., Vasiliev, A. D., Bezmaternykh, L. N., Nizhankovskii, V. I., Gavrilkin, S. Yu., Lamonova, K. V., and Ovchinnikov, S. G.
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
The Mn2BO4 single crystals have been grown using the flux technique. The careful study crystal structure and magnetic properties have been carried out. The antiferromagnet transition at TN = 26 K has been traced through the dc magnetization and specific heat temperature dependences. The magnetic uniaxial anisotropy has been detected with easy axis of magnetization lying in ab-plane. A reduction of the effective magnetic moment value is assigned to the non-quenched orbital moment of Jahn-Teller Mn3+ ions. Based on the superexchange interactions calculations the magnetic behavior is discussed., Comment: 20 pages, 5 figures, 3 tables
- Published
- 2015
- Full Text
- View/download PDF
26. Parallel stability analysis of membrane lamellar structures and foam films
- Author
-
Ivanova, N. G. and Tsekov, R.
- Subjects
Condensed Matter - Soft Condensed Matter ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
In the frames of the DLVO theory the root mean square amplitude of capillary waves in a thin liquid film is calculated and its dependence on some important physical parameters is unveiled. Two important models are considered: films with classical interfaces and films between lipid bilayers. The performed numerical analysis demonstrates essential difference in their behavior due to the different elastic properties of the film surfaces. It is shown that the film lifetime is significantly long at some magic film radii., Comment: The paper is dedicated to the 90th Anniversary of the Department of Physical Chemistry, University of Sofia. arXiv admin note: text overlap with arXiv:1304.6238
- Published
- 2015
27. Crystal and local atomic structure of Co-doped MgFeBO_4 warwickites
- Author
-
Kazak, N. V., Platunov, M. S., Knyazev, Yu. V., Ivanova, N. B., Zubavichus, Y. V., Veligzhanin, A. A., Vasiliev, A. D., Bezmaternykh, L. N., Bayukov, O. A., Arauzo, A., Bartolomé, J., Lamonova, K. V., and Ovchinnikov, S. G.
- Subjects
Condensed Matter - Materials Science - Abstract
Single crystalline MgFeBO_4, Mg_0.5Co_0.5FeBO_4 and CoFeBO_4 have been grown by the flux method. The samples have been characterized by X-ray spectral analysis, X-ray diffraction and X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra have been measured at the Fe andCoK-edges over a wide temperature range (6.5 - 300 K). The composition, the charge state and local environment of both Fe and Co atoms have been determined. The effects of Mg substitution by Co on the local structural distortions have been revealed experimentally and the M-O bond anisotropy has been found., Comment: 21 pages, 11 figures, 4 tables
- Published
- 2014
- Full Text
- View/download PDF
28. Mass Transfer from Giant Donors
- Author
-
Pavlovskii, K. and Ivanova, N.
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
The stability of mass transfer in binaries with convective giant donors remains an open question in modern astrophysics. There is a significant discrepancy between what the existing methods predict for a response to mass loss of the giant itself, as well as for the mass transfer rate during the Roche lobe overflow. Here we show that the recombination energy in the superadiabatic layer plays an important and hitherto unaccounted-for role in he donor's response to mass loss, in particular on its luminosity and effective temperature. Our improved optically thick nozzle method to calculate the mass transfer rate via $L_1$ allows us to evolve binary systems for a substantial Roche lobe overflow. We propose a new, strengthened criterion for the mass transfer instability, basing it on whether the donor experiences overflow through its outer Lagrangian point. We find that with the new criterion, if the donor has a well-developed outer convective envelope, the critical initial mass ratio for which a binary would evolve stably through the conservative mass transfer varies from $1.5$ to $2.2$, which is about twice as large as previously believed. In underdeveloped giants with shallow convective envelopes this critical ratio may be even larger. When the convective envelope is still growing, and in particular for most cases of massive donors, the critical mass ratio gradually decreases to this value, from that of radiative donors., Comment: Accepted to MNRAS
- Published
- 2014
- Full Text
- View/download PDF
29. Erosion as a Factor of Transformation of Soil Radioactive Contamination in the Basin of the Shchekino Reservoir (Tula Region)
- Author
-
Golosov, V. N., Ivanov, M. M., Tsyplenkov, A. S., Ivanov, M. A., Wakiyama, Y., Konoplev, A. V., Konstantinov, E. A., and Ivanova, N. N.
- Published
- 2021
- Full Text
- View/download PDF
30. Language Distribution in Sakha Family Communication: Traditions and Innovations
- Author
-
Ivanova, N. I., primary
- Published
- 2023
- Full Text
- View/download PDF
31. Regional features of state financial support for small and medium-sized enterprises
- Author
-
Zaharova, K. A., primary and Ivanova, N. V., additional
- Published
- 2023
- Full Text
- View/download PDF
32. On the role of recombination in common-envelope ejections
- Author
-
Ivanova, N., Justham, S., and Podsiadlowski, Ph.
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
The energy budget in common-envelope events (CEEs) is not well understood, with substantial uncertainty even over to what extent the recombination energy stored in ionised hydrogen and helium might be used to help envelope ejection. We investigate the reaction of a red-giant envelope to heating which mimics limiting cases of energy input provided by the orbital decay of a binary during a CEE, specifically during the post-plunge-in phase during which the spiral-in has been argued to occur on a time-scale longer than dynamical. We show that the outcome of such a CEE depends less on the total amount of energy by which the envelope is heated than on how rapidly the energy was transferred to the envelope and on where the envelope was heated. The envelope always becomes dynamically unstable before receiving net heat energy equal to the envelope's initial binding energy. We find two types of outcome, both of which likely lead to at least partial envelope ejection: "runaway" solutions in which the expansion of the radius becomes undeniably dynamical, and superficially "self-regulated" solutions, in which the expansion of the stellar radius stops but a significant fraction of the envelope becomes formally dynamically unstable. Almost the entire reservoir of initial helium recombination energy is used for envelope expansion. Hydrogen recombination is less energetically useful, but is nonetheless important for the development of the dynamical instabilities. However, this result requires the companion to have already plunged deep into the envelope; therefore this release of recombination energy does not help to explain wide post-common-envelope orbits., Comment: 17 pages, 10 figures, submitted to MNRAS. Comments are welcome
- Published
- 2014
- Full Text
- View/download PDF
33. Solutions and reductions for radiative energy transport in laser-heated plasma
- Author
-
Broadbridge, P. and Ivanova, N. M.
- Subjects
Mathematical Physics ,Mathematics - Analysis of PDEs - Abstract
A full symmetry classification is given for models of energy transport in radiant plasma when the mass density is spatially variable and the diffusivity is nonlinear. A systematic search for conservation laws also leads to some potential symmetries, and to an integrable nonlinear model. Classical point symmetries, potential symmetries and nonclassical symmetries are used to effect variable reductions and exact solutions. The simplest time-dependent solution is shown to be stable, and relevant to a closed system., Comment: 13 pages. arXiv admin note: text overlap with arXiv:math-ph/0605081, arXiv:1101.4755 by other authors
- Published
- 2014
- Full Text
- View/download PDF
34. Molecular Oncology Diagnosis: A System for Processing Data from Biochips Based on Field Effect Nanotransistors
- Author
-
Nikitaev, V. G., Pronichev, A. N., Hamadi, K. I., Druzhinina, E. A., Malsagova, K. A., Pleshakova, T. O., Romanova, T. S., Valueva, A. A., Ivanova, N. D., Safonova, V. K., Popov, V. P., Ziborov, V. S., Konev, V. A., and Ivanov, Yu. D.
- Published
- 2020
- Full Text
- View/download PDF
35. Comparison of thermal fluctuations in foam films and bilayer structures
- Author
-
Ivanova, N. G. and Tsekov, R.
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Soft Condensed Matter - Abstract
In the frames of the DLVO theory the root mean square amplitude and correlation length of capillary waves in thin liquid films are calculated. Their dependencies on some important physical parameters are studied. Two models are considered: films with classical interfaces and films between lipid bilayers. The performed numerical analysis demonstrates essential difference in their behavior, which is due to the different elastic properties of the film surfaces in the models.
- Published
- 2013
36. Galactic Ultracompact X-ray Binaries: Empirical Luminosities
- Author
-
Cartwright, T. F., Engel, M. C., Heinke, C. O., Sivakoff, G. R., Berger, J. J., Gladstone, J. C., and Ivanova, N.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Ultracompact X-ray binaries (UCXBs) are thought to have relatively simple binary evolution post-contact, leading to clear predictions of their luminosity function. We test these predictions by studying the long-term behavior of known UCXBs in our Galaxy, principally using data from the MAXI All-Sky Survey and the Galactic Bulge Scans with RXTE's PCA instrument. Strong luminosity variations are common (and well-documented) among persistent UCXBs, which requires an explanation other than the disk instability mechanism. We measure the luminosity function of known UCXBs in the Milky Way, which extends to lower luminosities than some proposed theoretical luminosity functions of UCXBs. The difference between field and globular cluster X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in globular clusters. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few times 10^36 ergs/s in both old field populations and globular clusters., Comment: 17 pages, 7 pages of which are 6 multi-part figures. ApJ, in press
- Published
- 2013
- Full Text
- View/download PDF
37. Galactic Ultracompact X-ray Binaries: Disk Stability and Evolution
- Author
-
Heinke, C. O., Ivanova, N., Engel, M. C., Pavlovskii, K., Sivakoff, G. R., Cartwright, T. F., and Gladstone, J. C.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We study the mass transfer rates and disk stability conditions of ultracompact X-ray binaries (UCXBs) using empirical time-averaged X-ray luminosities from Paper I (Cartwright et al. 2013) and compiled information from the literature. The majority of UCXBs are consistent with evolutionary tracks for white dwarf donors. Three UCXBs with orbital periods longer than 40 minutes have mass transfer rates above 10^{-10} Msun/year, inconsistent with white dwarf donor tracks. We show that if helium star donors can retain their initial high entropy, they can explain the observed mass transfer rates of these UCXBs. Several UCXBs show persistent luminosities apparently below the disk instability limit for irradiated He accretion disks. We point out that a predominantly C and/or O disk (as observed in the optical spectra of several) lowers the disk instability limit, explaining this disagreement. The orbital period and low time-averaged mass transfer rate of 2S 0918-549 provide evidence that the donor star is a low-entropy C/O white dwarf, consistent with optical spectra. We combine existing information to constrain the masses of the donors in 4U 1916-053 (0.064+-0.010 Msun) and 4U 1626-67 (<0.036 Msun for a 1.4 Msun neutron star). We show that 4U 1626-67 is indeed persistent, and not undergoing a transient outburst, leaving He star models as the best explanation for the donor., Comment: 13 pages, 7 figures, ApJ in press
- Published
- 2013
- Full Text
- View/download PDF
38. Identification of the Long-Sought Common-Envelope Events
- Author
-
Ivanova, N., Justham, S., Nandez, J. L. Avendano, and Lombardi Jr, J. C.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Common-envelope events (CEEs), during which two stars temporarily orbit within a shared envelope, are believed to be vital for the formation of a wide range of close binaries. For decades, the only evidence that CEEs actually occur has been indirect, based on the existence of systems that could not be otherwise explained. Here we propose a direct observational signature of CEE arising from a physical model where emission from matter ejected in a CEE is controlled by a recombination front as the matter cools. The natural range of timescales and energies from this model, as well the expected colors, light-curve shapes, ejection velocities and event rate, match those of a recently-recognized class of red transient outbursts., Comment: 6 main and 22 supplemental pages, 5 total figures, one table and 2 movies. This is the authors version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science, vol 339, 2013, http://www.sciencemag.org/content/339/6118/433.abstract
- Published
- 2013
- Full Text
- View/download PDF
39. Geochemistry of deep Tunguska Basin sills, Siberian Traps: correlations and potential implications for the end-Permian environmental crisis
- Author
-
Callegaro, S., Svensen, H. H., Neumann, E. R., Polozov, A. G., Jerram, D. A., Deegan, F. M., Planke, S., Shiganova, O. V., Ivanova, N. A., and Melnikov, N. V.
- Published
- 2021
- Full Text
- View/download PDF
40. Common Envelope Evolution: Where we stand and how we can move forward
- Author
-
Ivanova, N., Justham, S., Chen, X., De Marco, O., Fryer, C. L., Gaburov, E., Ge, H., Glebbeek, E., Han, Z., Li, X. -D., Lu, G., Marsh, T., Podsiadlowski, Ph., Potter, A., Soker, N., Taam, R., Tauris, T. M., Heuvel, E. P. J. van den, and Webbink, R. F.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas of consensus and disagreement, and stress ideas which should point the way forward for progress in this important but long-standing and largely unconquered problem. Unusually for CEE-related work, we mostly try to avoid relying on results from population synthesis or observations, in order to avoid potentially being misled by previous misunderstandings. As far as possible we debate all the relevant issues starting from physics alone, all the way from the evolution of the binary system immediately before CEE begins to the processes which might occur just after the ejection of the envelope. In particular, we include extensive discussion about the energy sources and sinks operating in CEE, and hence examine the foundations of the standard energy formalism. Special attention is also given to comparing the results of hydrodynamic simulations from different groups and to discussing the potential effect of initial conditions on the differences in the outcomes. We compare current numerical techniques for the problem of CEE and also whether more appropriate tools could and should be produced (including new formulations of computational hydrodynamics, and attempts to include 3D processes within 1D codes). Finally we explore new ways to link CEE with observations. We compare previous simulations of CEE to the recent outburst from V1309 Sco, and discuss to what extent post-common-envelope binaries and nebulae can provide information, e.g. from binary eccentricities, which is not currently being fully exploited., Comment: 83 pages (11 chapters, 2 appendixes), 10 figures, Astronomy & Astrophysics Review format. This version contains revisions as a response to community comments
- Published
- 2012
- Full Text
- View/download PDF
41. On the origin of the metallicity dependence in dynamically formed extragalactic low-mass X-ray binaries
- Author
-
Ivanova, N., Fragos, T., Kim, D. -W., Fabbiano, G., Nandez, J. L. Avendano, Lombardi, J. C., Sivakoff, G. R., Voss, R., and Jordan, A.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Globular clusters (GCs) effectively produce dynamically-formed low-mass X-ray binaries (LMXBs). Observers detect ~100 times more LMXBs per stellar mass in GCs compared to stars in the fields of galaxies. It has also been observationally established that metal-rich GCs are about 3 times more likely to contain an X-ray source than their metal-poor counterparts. Recent observations have shown that this ratio holds in extragalactic GCs for all bright X-ray sources with Lx between 2X10^{37} and 5X10^{38} erg/s. In this Letter, we propose that the observed metallicity dependence of LMXBs in extragalactic GCs can be explained by the differences in the number densities and average masses of red giants in populations of different metallicities. Red giants serve as seeds for the dynamical production of bright LMXBs via two channels - binary exchanges and physical collisions - and the increase of the number densities and masses of red giants boost LMXB production, leading to the observed difference. We also discuss a possible effect of the age difference in stellar populations of different metallicities., Comment: 5 pages, 2 figures, submitted to ApJL
- Published
- 2012
- Full Text
- View/download PDF
42. Metallicity Effect on LMXB Formation in Globular Clusters
- Author
-
Kim, D. -W., Fabbiano, G., Ivanova, N., Fragos, T., Jordan, A., Sivakoff, G., and Voss, R.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies - Abstract
We present comprehensive observational results of the metallicity effect on the fraction of globular clusters (GC) that contain low-mass X-ray binaries (LMXB), by utilizing all available data obtained with Chandra for LMXBs and HST ACS for GCs. Our primary sample consists of old elliptical galaxies selected from the ACS Virgo and Fornax surveys. To improve statistics at both the lowest and highest X-ray luminosity, we also use previously reported results from other galaxies. It is well known that the LMXB fraction is considerably higher in red, metal-rich, than in blue, metal-poor GCs. In this paper, we test whether this metallicity effect is X-ray luminosity-dependent, and find that the effect holds uniformly in a wide luminosity range. This result is statistically significant (at >= 3 sigma) in LMXBs with luminosities in the range LX = 2 x 10^37 - 5 x 10^38 erg s-1, where the ratio of LMXB fractions in metal-rich to metal-poor GCs is R = 3.4 +- 0.5. A similar ratio is also found at lower (down to 10^36 erg s-1) and higher luminosities (up to the ULX regime), but with less significance (~2 sigma confidence). Because different types of LMXBs dominate in different luminosities, our finding requires a new explanation for the metallicity effect in dynamically formed LMXBs. We confirm that the metallicity effect is not affected by other factors such as stellar age, GC mass, stellar encounter rate, and galacto-centric distance., Comment: 21 pages, 5 figures, accepted in ApJ
- Published
- 2012
- Full Text
- View/download PDF
43. Can We Trust Models for Adiabatic Mass Loss?
- Author
-
Woods, T. E. and Ivanova, N.
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
In interacting binaries, comparison of a donor star's radial response to mass loss with the response of its Roche radius determines whether mass loss persists and, if so, determines the timescale and stability of the ensuing evolutionary phase. For giants with deep convective envelopes, the canonical description holds that once mass transfer begins it typically proceeds catastrophically on the dynamical timescale, as the star cannot lose sufficient heat in order to avoid expansion. However, we demonstrate that the local thermal timescale of the envelope's superadiabatic outer surface layer remains comparable to that of mass loss in most cases of "dynamical" mass loss. We argue therefore that if mass loss proceeds on a timescale longer than this, then even a deep convective envelope will not dramatically expand, as the surface layer will have time to relax thermally and reconstitute itself. We demonstrate that in general the polytropic approximation gives much too strict a criterion for stability, and discuss the dependence of the donor's response on its radius in addition to its core mass. In general, we find that the effective response of the donor on rapid timescales cannot be determined accurately without detailed evolutionary calculations., Comment: 5 pages, 4 figures, 1 table. ApJL accepted
- Published
- 2011
- Full Text
- View/download PDF
44. On The Formation of Double White Dwarfs: Reevaluating How We Parametrize the Common Envelope Phase
- Author
-
Woods, T. E., Ivanova, N., van der Sluys, M., and Chaichenets, S.
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
One class of compact binaries of special interest is that of double white dwarfs (DWDs). For many of these systems, the exact nature of the evolutionary channels by which they form remains uncertain. The canonical explanation calls for the progenitor binary system to undergo two subsequent mass-transfer events, both of which are unstable and lead to a common envelope (CE) phase. However, it has been shown that if both CE events obey the standard alpha prescription, it is not possible to reproduce all of the observed systems. As an alternative prescription, the gamma-formalism was proposed, which parametrizes the fraction of angular momentum carried away with mass loss, in contrast to the alpha prescription, which parametrizes energy loss. We demonstrate that the gamma-prescription is also inadequate in describing the evolution of an arbitrary DWD binary; clearly we require a deeper understanding of the physical mechanisms underlying their formation. We then present a detailed model for the evolution of Red Giant -- Main Sequence binaries during the first episode of mass transfer, and demonstrate that their evolution into DWDs need not arise through two phases of dynamical mass loss. Instead, the first episode of dramatic mass loss may be stable, non-conservative mass transfer. The second phase is then well described by the alpha prescription. We find that the considered progenitors can reproduce the properties of the observed helium DWDs in which the younger component is the more massive., Comment: 6 pages, 2 figures. Proceedings for the ESO Conference, the workshop 'Evolution of Compact Binaries', 6-11 March 2011, Vi\~na del Mar, Chile, edited by L. Schmidtobreick, M. R. Schreiber, C. Tappert, ASP conference series
- Published
- 2011
45. On the Formation of Double White Dwarfs through Stable Mass Transfer and a Common Envelope
- Author
-
Woods, T. E., Ivanova, N., van der Sluys, M., and Chaichenets, S.
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
Although several dozen double white dwarfs (DWDs) have been observed, for many the exact nature of the evolutionary channel(s) by which they form remains uncertain. The canonical explanation calls for the progenitor binary system to undergo two subsequent mass-transfer events, both of which are unstable and lead to a common envelope (CE). However, it has been shown that if both CE events obey the standard alpha-prescription (parametrizing energy loss), it is not possible to reproduce all of the observed systems. The gamma-prescription was proposed as an alternative to this description, instead parametrizing the fraction of angular momentum carried away in dynamical-timescale mass loss. In this paper, we analyze simultaneous energy and angular-momentum conservation, and show that the gamma-prescription cannot adequately describe a CE event for an arbitrary binary, nor can the first phase of mass loss always be understood in general as a dynamical-timescale event. We consider in detail the first episode of mass transfer in binary systems with initially low companion masses, with a primary mass in the range 1.0--1.3 solar masses and an initial mass ratio between the secondary and primary stars of 0.83--0.92. In these systems, the first episode of dramatic mass loss may be stable, non-conservative mass transfer. This strips the donor's envelope and dramatically raises the mass ratio; the considered progenitor binary systems can then evolve into DWDs after passing through a single CE during the second episode of mass loss. We find that such a mechanism reproduces the properties of the observed DWD systems which have an older component with less than approximately 0.46 solar masses and mass ratios between the younger and older WDs greater than 1., Comment: Submitted to ApJ, ApJ format. 15 pages, 17 figures, 2 tables
- Published
- 2011
- Full Text
- View/download PDF
46. The Formation of Low-Mass Double White Dwarfs through an Initial Phase of Stable Non-Conservative Mass Transfer
- Author
-
Woods, T. E., Ivanova, N., van der Sluys, M., and Chaichenets, S.
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
Although many double white dwarfs (DWDs) have been observed, the evolutionary channel by which they are formed from low-mass/long-period red-giant-main-sequence (RG-MS) binaries remains uncertain. The canonical explanations involve some variant of double common-envelope (CE) evolution, however it has been found that such a mechanism cannot produce the observed distribution. We present a model for the initial episode of mass transfer (MT) in RG-MS binaries, and demonstrate that their evolution into double white dwarfs need not arise through a double-CE process, as long as the initial primary's core mass (Md,c) does not exceed 0.46M$_{\odot}$. Instead, the first episode of dramatic mass loss may be stable, non-conservative MT. We find a lower bound on the fraction of transferred mass that must be lost from the system in order to provide for MT, and demonstrate the feasibility of this channel in producing observed low-mass (with M$_{d,c}$ < 0.46M$_{\odot}$) DWD systems., Comment: 2 pages, 1 figure, Conference Proceedings for the International Conference on Binaries, Mykonos, Greece
- Published
- 2010
- Full Text
- View/download PDF
47. Formation of black-hole X-ray binaries in globular clusters
- Author
-
Ivanova, N., Chaichenets, S., Fregeau, J., Heinke, C. O., Lombardi Jr., J. C., and Woods, T.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Inspired by the recent identification of the first candidate BH-WD X-ray binaries, where the compact accretors may be stellar-mass black hole candidates in extragalactic globular clusters, we explore how such binaries could be formed in a dynamical environment. We provide analyses of the formation rates via well known formation channels like binary exchange and physical collisions and propose that the only possibility to form BH-WD binaries is via coupling these usual formation channels with subsequent hardening and/or triple formation. Indeed, we find that the most important mechanism to make a BH-WD X-ray binary from an initially dynamically formed BH-WD binary is triple induced mass transfer via the Kozai mechanism. Even using the most optimistic estimates for the formation rates, we cannot match the observationally inferred production rates if black holes undergo significant evaporation from the cluster or form a completely detached subcluster of black holes. We estimate that at least 1% of all formed black holes, or presumably 10% of the black holes present in the core now, must be involved in interactions with the rest of the core stellar population., Comment: 10 pages, 2 figures, submitted to ApJ
- Published
- 2010
- Full Text
- View/download PDF
48. Evolution of the Binary Fraction in Dense Stellar Systems
- Author
-
Fregeau, J. M., Ivanova, N., and Rasio, F. A.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
Using our recently improved Monte Carlo evolution code, we study the evolution of the binary fraction in globular clusters. In agreement with previous N-body simulations, we find generally that the hard binary fraction in the core tends to increase with time over a range of initial cluster central densities for initial binary fractions <~ 90%. The dominant processes driving the evolution of the core binary fraction are mass segregation of binaries into the cluster core and preferential destruction of binaries there. On a global scale, these effects and the preferential tidal stripping of single stars tend to roughly balance, leading to overall cluster binary fractions that are roughly constant with time. Our findings suggest that the current hard binary fraction near the half-mass radius is a good indicator of the hard primordial binary fraction. However, the relationship between the true binary fraction and the fraction of main-sequence stars in binaries (which is typically what observers measure) is non-linear and rather complicated. We also consider the importance of soft binaries, which not only modify the evolution of the binary fraction, but can drastically change the evolution of the cluster as a whole. Finally, we describe in some detail the recent addition of single and binary stellar evolution to our cluster evolution code., Comment: 8 pages, 7 figures in emulateapj format. Submitted to ApJ
- Published
- 2009
- Full Text
- View/download PDF
49. The influence of inlet flow asymmetry on the carotid bifurcation hemodynamics.
- Author
-
Borisov, V G, Zakharov, Yu N, Derbilova, V P, Vinogradov, R A, and Ivanova, N V
- Published
- 2024
- Full Text
- View/download PDF
50. Chronic Disorders of Consciousness: guidelines of the All-Russian public organization “Federation of Anesthesiologists and Reanimatologists”
- Author
-
Belkin, A. A., primary, Aleksandrova, E. V., additional, Akhutina, T. V., additional, Belkin, V. A., additional, Berdnikovich, E. S., additional, Bykova, V. I., additional, Varako, N. A., additional, Voznyuk, I. A., additional, Gnedovskaya, E. V., additional, Grigoryeva, V. N., additional, Zaytsev, O. S., additional, Zinchenko, Yu. P., additional, Ivanova, G. E., additional, Ivanova, N. E., additional, Kovyazina, M. S., additional, Kondratyev, A. N., additional, Kondratyeva, E. A., additional, Kondratyev, S. A., additional, Krylov, V. V., additional, Latyshev, Ya. A., additional, Lebedinskii, K. M., additional, Legostaeva, L. A., additional, Maksakova, O. A., additional, Martynov, M. Yu., additional, Mikadze, Yu. V., additional, Petrikov, S. S., additional, Petrova, M. V., additional, Piradov, M. A., additional, Popugaev, K. A., additional, Pryanikov, I. V., additional, Ryabinkina, Yu. V., additional, Savin, I. A., additional, Sergeev, Dmitry V., additional, Sinkin, M. V., additional, Skvortsov, A. A., additional, Skripay, E. Yu., additional, Suvorov, A. Yu., additional, Suponeva, N. A., additional, Usachev, D. Yu., additional, Fufaeva, E. V., additional, Shamalov, N. A., additional, Shchegolev, A. V., additional, Iazeva, E. G., additional, and Zabolotskikh, I. B., additional
- Published
- 2023
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.