89 research outputs found
Opacity, variability and kinematics of AGN jets
Synchrotron self-absorption in active galactic nuclei (AGN) jets manifests
itself as a time delay between flares observed at high and low radio
frequencies. It is also responsible for the observing frequency dependent
change in size and position of the apparent base of the jet, aka the core shift
effect, detected with very long baseline interferometry (VLBI). We measure the
time delays and the core shifts in 11 radio-loud AGN to estimate the speed of
their jets without relying on multi-epoch VLBI kinematics analysis. The 158
GHz total flux density time lags are obtained using Gaussian process
regression, the core shift values are measured using VLBI observations and
adopted from the literature. A strong correlation is found between the apparent
core shift and the observed time delay. Our estimate of the jet speed is higher
than the apparent speed of the fastest VLBI components by the median
coefficient of 1.4. The coefficient ranges for individual sources from 0.5 to
20. We derive Doppler factors, Lorentz factors and viewing angles of the jets,
as well as the corresponding de-projected distance from the jet base to the
core. The results support evidence for acceleration of the jets with bulk
motion Lorentz factor on de-projected scales
of 0.5500 parsecs.Comment: Accepted by MNRAS; 11 pages, 11 figures, 3 table
Хорватське питання в тлумаченні Михайла Грушевського (Interpretation of the Croatian Question by Mykhailo Hrushevskyi)
У тексті проаналізована позиція М.С. Грушевського щодо хорватського питання. Варто пригадати, що спостереження М.С. Грушевського недостатньо беруться до уваги у деяких сучасних публікаціях українського білохорватства, що потребує конкретизації його висновків у головних положеннях. Хорватське питання було розглянуте вченим на сторінках першого тому «Історії України-Руси». Ця надзвичайно актуальна проблема хорватського етногенезу стосується української і хорватської славістики та все ж досі залишається відкритою через обмеженість джерельної бази.
(The author of the research focuses attention on the position of Mykhailo Hrushevskyi regarding the Croatian question. It is worth mentioning that Mykhailo Hrushevskyi’s observations are not taken into account in some modern publications of the Ukrainian White Croats that requires concretization concerning the findings about the key positions. The Croatian question has been considered by the scholar on pages of the first volume The History of Ukraine-Rus. This extremely urgent problem of the Croatian ethno genesis concerns the Ukrainian and Croatian Slavic studies and still remains open due to a limited source basis.
The Improvement of The Leisure Management System At The Local Level (By The Example of “Sumy Leisure Center of Youth”)
The theme the leisure of youth in our country does not lose its relevance. How
to rely on creative types of leisure activities and ensure direct participation of each
individual is the main question of formation of personal qualities that promote
active leisure activities and major factors in the development of social
infrastructure. The situation in the state requires immediate implementation of
measures aimed at further improving of mechanisms of the state youth policy
realization in Ukraine
Properties of the jet in M87 revealed by its helical structure imaged with the VLBA at 8 and 15 GHz
We present full-track high-resolution radio observations of the jet of the
galaxy M87 at 8 and 15 GHz. These observations were taken over three
consecutive days in May 2009 using the Very Long Baseline Array (VLBA), one
antenna of the Very Large Array (VLA), and the Effelsberg 100 m telescope. Our
produced images have dynamic ranges exceeding 20,000:1 and resolve linear
scales down to approximately 100 Schwarzschild radii, revealing a
limb-brightened jet and a faint, steep spectrum counter-jet. We performed
jet-to-counter-jet analysis, which helped estimate the physical parameters of
the flow. The rich internal structure of the jet is dominated by three helical
threads, likely produced by the Kelvin-Helmholtz (KH) instability developing in
a supersonic flow with a Mach number of approximately 20 and an enthalpy ratio
of around 0.3. We produce a CLEAN imaging bias-corrected 8-15GHz spectral index
image, which shows spectrum flattening in regions of helical thread
intersections. This further supports the KH origin of the observed internal
structure of the jet. We detect polarised emission in the jet at distances of
approximately 20 milliarcseconds from the core and find Faraday rotation which
follows a transverse gradient across the jet. We apply Faraday rotation
correction to the polarisation position angle and find that the position angle
changes as a function of distance from the jet axis, which suggests the
presence of a helical magnetic field.Comment: 15 pages, 10 figures, 1 table, Submitted to MNRAS on 25th March 202
Thermal and magnetic properties of integrable spin-1 and spin-3/2 chains with applications to real compounds
The ground state and thermodynamic properties of spin-1 and spin-3/2 chains
are investigated via exactly solved su(3) and su(4) models with physically
motivated chemical potential terms. The analysis involves the Thermodynamic
Bethe Ansatz and the High Temperature Expansion (HTE) methods. For the spin-1
chain with large single-ion anisotropy, a gapped phase occurs which is
significantly different from the valence-bond-solid Haldane phase. The
theoretical curves for the magnetization, susceptibility and specific heat are
favourably compared with experimental data for a number of spin-1 chain
compounds. For the spin-3/2 chain a degenerate gapped phase exists starting at
zero external magnetic field. A middle magnetization plateau can be triggered
by the single-ion anisotropy term. Overall, our results lend further weight to
the applicability of integrable models to the physics of low-dimensional
quantum spin systems. They also highlight the utility of the exact HTE method.Comment: 38 pages, 15 figure
Geographical Distribution, Incidence, Malignancies, and Outcome of 136 Eastern Slavic Patients With Nijmegen Breakage Syndrome and NBN Founder Variant c.657_661del5
Nijmegen breakage syndrome (NBS) is a DNA repair disorder characterized by combined immunodeficiency and a high predisposition to lymphoid malignancies. The majority of NBS patients are identified with a homozygous five base pair deletion in the Nibrin (NBN) gene (c.657_661del5, p.K219fsX19) with a founder effect observed in Caucasian European populations, especially of Slavic origin. We present here an analysis of a cohort of 136 NBS patients of Eastern Slav origin across Belarus, Ukraine, Russia, and Latvia with a focus on understanding the geographic distribution, incidence of malignancy, and treatment outcomes of this cohort. Our analysis shows that Belarus had the highest prevalence of NBS (2.3 per 1,000,000), followed by Ukraine (1.3 per 1,000,000), and Russia (0.7 per 1,000,000). Of note, the highest concentration of NBS cases was observed in the western regions of Belarus and Ukraine, where NBS prevalence exceeds 20 cases per 1,000,000 people, suggesting the presence of an “Eastern Slavic NBS hot spot.” The median age at diagnosis of this cohort ranged from 4 to 5 years, and delay in diagnosis was more pervasive in smaller cities and rural regions. A total of 62 (45%) patients developed malignancies, more commonly in males than females (55.2 vs. 34.2%; p=0.017). In 27 patients, NBS was diagnosed following the onset of malignancies (mean age: 8 years). Malignancies were mostly of lymphoid origin and predominantly non-Hodgkin lymphoma (NHL) (n=42, 68%); 38% of patients had diffuse large B-cell lymphoma. The 20-year overall survival rate of patients with malignancy was 24%. However, females with cancer experienced poorer event-free survival rates than males (16.6% vs. 46.8%, p=0.036). Of 136 NBS patients, 13 underwent hematopoietic stem cell transplantation (HSCT) with an overall survival of 3.5 years following treatment (range: 1 to 14 years). Indications for HSCT included malignancy (n=7) and immunodeficiency (n=6). Overall, 9% of patients in this cohort reached adulthood. Adult survivors reported diminished quality of life with significant physical and cognitive impairments. Our study highlights the need to improve timely diagnosis and clinical management of NBS among Eastern Slavs. Genetic counseling and screening should be offered to individuals with a family history of NBS, especially in hot spot regions. © Copyright © 2021 Sharapova, Pashchenko, Bondarenko, Vakhlyarskaya, Prokofjeva, Fedorova, Savchak, Mareika, Valiev, Popa, Tuzankina, Vlasova, Sakovich, Polyakova, Rumiantseva, Naumchik, Kulyova, Aleshkevich, Golovataya, Minakovskaya, Belevtsev, Latysheva, Latysheva, Beznoshchenko, Akopyan, Makukh, Kozlova, Varabyou, Ballow, Ong, Walter, Kondratenko, Kostyuchenko and Aleinikova.We thank all doctors for clinical help for patients. We also appreciate the support of patient and their parents for agreeing to take part in this study. TP thanks Sergey?Nikulshin, Marika Grutupa, and Zanna Kovalova. We thank Joseph Dasso for editing this manuscript, primarily for proper English
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