In 1956, H. Lenz introduced a problem to find members of the sequence
d
n
=
inf
Φ
x
∈
R
+
:
Φ
⊂
Φ
1
∪
Φ
2
∪
⋯
∪
Φ
n
,
diam
Φ
i
≤
x
f
o
r
a
l
l
i
where the infimum is taken over all sets Φ of unit ...diameter. In the present paper, an upper bound for
d
6
is improved to 0.53432….
Abstract
Apurinic/apyrimidinic (AP) sites are abundant DNA lesions arising from spontaneous hydrolysis of the N-glycosidic bond and as base excision repair (BER) intermediates. AP sites and their ...derivatives readily trap DNA-bound proteins, resulting in DNA–protein cross-links. Those are subject to proteolysis but the fate of the resulting AP–peptide cross-links (APPXLs) is unclear. Here, we report two in vitro models of APPXLs synthesized by cross-linking of DNA glycosylases Fpg and OGG1 to DNA followed by trypsinolysis. The reaction with Fpg produces a 10-mer peptide cross-linked through its N-terminus, while OGG1 yields a 23-mer peptide attached through an internal lysine. Both adducts strongly blocked Klenow fragment, phage RB69 polymerase, Saccharolobus solfataricus Dpo4, and African swine fever virus PolX. In the residual lesion bypass, mostly dAMP and dGMP were incorporated by Klenow and RB69 polymerases, while Dpo4 and PolX used primer/template misalignment. Of AP endonucleases involved in BER, Escherichia coli endonuclease IV and its yeast homolog Apn1p efficiently hydrolyzed both adducts. In contrast, E. coli exonuclease III and human APE1 showed little activity on APPXL substrates. Our data suggest that APPXLs produced by proteolysis of AP site-trapped proteins may be removed by the BER pathway, at least in bacterial and yeast cells.
Graphical Abstract
Graphical Abstract
Using the general circulation model of the middle and
upper atmosphere (MUAM), a number of numerical scenarios were implemented to
study the impact of individual planetary waves (PWs) on the global
...atmospheric circulation, including zonal wind, temperature, and residual
meridional circulation (RMC). The calculations were performed for the winter
conditions of the Northern Hemisphere (January–February). We show the contribution
to the formation of the dynamic and temperature regimes of the MUAM made by equatorial Kelvin waves propagating to the east, as
well as atmospheric normal modes (NMs) with periods from 4 to 16 d. In
particular, it is demonstrated that the impact of a 5 d PW and an
ultra-fast Kelvin wave (UFKW) can change the speed of circulation flows by up to
6 % in the areas of their amplitude maxima. At the same time, this effect
can be significantly enhanced in certain periods of time. The presented
research results are important for a deeper understanding of the mechanisms
of large-scale atmospheric interactions. Despite the obviousness and
simplicity of the problem, such work has not been carried out yet.
The COVID-19 pandemic has brought significant changes in managing of patients with rheumatoid arthritis. Rituximab-treated patients were more susceptible to severe infection. This required a “switch” ...to another genetically engineered drug in the patients with high risk of adverse COVID-19. In this study, we assessed the severity of immune response to SARS-CoV-2 antigens in rituximab-treated patients with rheumatoid arthritis vaccinated with the combined vector vaccine Gam-COVID-Vac. Insufficient formation of the humoral response and a high level of T-cell response to SARS-CoV-2 antigens in this group of patients were revealed. An imbalance of cellular and humoral response may play a role in more severe COVID-19 in rituximab-treated patients with rheumatoid arthritis.
Purpose. Development of a procedure for determining the optimal capital-labor ratio within the framework of two-factor production functions, as well as an analysis of the conditions for its ...implementation in practice. Methodology. In the process of the conducted mathematical analysis, the search for the extrema of the most popular in economic studies, of two-factor production functions, namely the Cobb-Douglas production function, CES-function, linear function, Allen's function in terms of capital assets, was performed. The limit rate of the technological substitution of factors in conditions of optimal capital-labor ratio was found, which proved to be unique in all investigated production functions. The indicated relationship was verified on the basis of microeconomic theory, in particular, using the equilibrium principle. Findings. The hypothesis of the single marginal rate of technological substitution in conditions of optimal capital-labor ratio is verified. On the basis of the microeconomic theory, the procedure for determining the optimal capital-labor ratio in the framework of any two-factor production functions is substantiated due to the marginal rate of technological substitution. The proposed procedure consists in determining the marginal rate of technological substitution as the ratio of the marginal products of the production factors and equating it to one unit. The obtained ratio makes it possible to deduce the formula of optimal capital-labor ratio, provided that the indicators of the dynamics of realized products, main assets and labor remuneration in the enterprise are adequately described by the corresponding production function with non-zero substitution. Originality. Development of a procedure for optimization of capital-labor ratio within the framework of substitutional twofactor production functions based on the formulas of their marginal rate of technological substitution. Practical value. Theoretical conclusions and proposals were tested on the example of a Ukrainian enterprise in the field of mechanical engineering. The results of the research can be used to manage capital-labor ratio by determining its optimal volume in production, which opens the possibility of rational use of basic productive assets and labor at domestic enterprises which are characterized by relative over-equipment with high moral and physical equipment decay.
Purpose. To substantiate an approach to road development investment management in Ukraine in compliance with the principle of syncretism and the use of Quality Function Deployment methodology, to ...improve the methodological approach to calculating the concession fee for brown-field and green-field road concession projects. Methodology. The study used a set of general and special methods of cognition: the Quality Function Deployment (QFD) method, the environmental approach, multimodal analysis, Decoupling Index, Decoupling Factor, logical generalization, quantitative and qualitative comparison, scientific abstraction and systematization. Findings. According to the results of research on interrelation of cost of an investment project and volumes of works by their types, an economic-mathematical model of estimation of need for investments in projects for construction, reconstruction, repair and maintenance of public motor roads is offered. The proposed model, unlike the existing ones, is based on lateral understanding of the clarity of delineation of capital needs by type of road construction, which will provide taking management decisions on investment projects with model and information tools that will help obtain the most realistic assessment of need for capital needed to improve the transport operation condition of motor roads in Ukraine. Originality. The organizational-economic mechanism of management of investment activity of road economy and the estimation of efficiency of co-financing investment projects under programs on construction, reconstruction, repair and maintenance of motor roads is advanced. The diagnostics of efficiency of investment of construction of public motor roads under public-private partnership in the form of concession is improved. Practical value. The results of the study can be used in the activities of road industry of Ukraine for the development and implementation of investment projects under motor road development programs.
—Superbubbles driven by supernovae explosions are sometimes considered as a source of triggering star formation. Using three dimensional simulations we consider the dynamics and stability of a gas ...layer between interacting bubbles of different age located in the galaxy disk midplane. It is shown that the lifetime of a dense gas layer increases for the interacting bubbles formed by supernovae explosions when the separation between the clusters is larger than the scale height of the disc. In case of interacting young bubbles a dense “wall” between them is rapidly destroyed by shock waves coming from hot interiors. It was found that dense gas “survives” at the edges of the interacting layer and its mass gradually increases. The possibility of star formation at the edges of the layer is discussed and compared with observations of star formation regions in nearby dwarf galaxies.
Abstract
Background
Substantial research is dedicated to understanding the aging-related dynamics among individual differences in level, change, and variation across physical and cognitive abilities. ...Evaluating replicability and synthesizing these findings has been limited by differences in measurements and samples, and by study design and statistical analyses confounding between-person differences with within-person changes. In this article, we conducted a coordinated analysis and summary meta-analysis of new results on the aging-related dynamics linking pulmonary function and cognitive performance.
Methods
We performed coordinated analysis of bivariate growth models in data from 20,586 participants across eight longitudinal studies to examine individual differences in baseline level, rate of change, and occasion-specific variability in pulmonary and cognitive functioning. Results were summarized using meta-analysis.
Results
We found consistent but weak baseline and longitudinal associations in levels of pulmonary and cognitive functioning, but no associations in occasion-specific variability.
Conclusions
Results provide limited evidence for a consistent link between simultaneous changes in pulmonary and cognitive function in a normal aging population. Further research is required to understand patterns of onset of decline and differences in rates of change within and across physical and cognitive functioning domains, both within-individuals and across countries and birth cohorts. Coordinated analysis provides an efficient and rigorous approach for replicating and comparing results across independent longitudinal studies.
Ensemble simulation of the atmospheric general
circulation at altitudes up to the lower thermosphere is performed using the
3-D nonlinear mechanistic numerical model MUAM. The residual mean ...meridional
circulation (RMC), which is the superposition of the mean Eulerian and
wave-induced eddy components, is calculated for the boreal winter. Changes
in the vertical and meridional RMC velocity components are analysed at
different stages of a simulated composite sudden stratospheric warming (SSW)
event averaged over 19 model runs. The simulation results show a general
decrease in RMC velocity components up to 30 % during and after SSW in the
mesosphere and lower thermosphere of the Northern Hemisphere. There are also
increases in the downward and northward velocities at altitudes of 20–50 km at
the northern polar latitudes during SSW. Associated vertical transport and
adiabatic heating can contribute to warming the stratosphere and downward
shifting of the stratopause during the composite SSW. The residual mean and
eddy mass fluxes are calculated for different SSW stages. It is shown that
before the SSW, planetary wave activity creates wave-induced eddy
circulation cells in the northern upper stratosphere, which are directed
upwards at middle latitudes, northward at high latitudes and downwards near
the North Pole. These cells increase heat transport and adiabatic heating in
the polar region. During SSW, the region of upward eddy vertical velocity is
shifted to high latitudes, but the velocity is still downward near the North
Pole. After SSW, upward eddy-induced fluxes span the entire polar region,
producing upward transport and adiabatic cooling of the stratosphere and
providing the return of the stratopause to higher altitudes. The obtained
statistically significant results on the evolution of RMC and eddy
circulation at different SSW stages at altitudes up to the lower
thermosphere can be useful for a better understanding the mechanisms of planetary
wave impacts on the mean flow and for the diagnostics of the transport of
conservative tracers in the atmosphere.
We study welded joints of annealed sheets 6 mm in thickness made of D16M (Al–Cu–Mg) aluminum alloy, which is an analog of the foreign 2024 alloy currently attributed to difficultly welded alloys. The ...joints are made by the impulsive-arc method with consumable electrode with the use of a Zv1201 (Al–6.3Cu–0.3Mn) filler wire and technological inserts made of 7056 (Al–9.5Zn–1.8Mg–1.6Cu), V96 (Al–8.5Zn–2.6Mg–2.3Cu), and V92 (Al–3.5Zn–4.2Mg–0.5Cu) alloys. We study the regularities of changes in the microstructure, hardness, strength, and cyclic crack growth resistance of the joints after welding and also in the course of subsequent artificial aging or quenching and artificial aging after welding. It is established that the strength of welded joints after thermal treatment does not exceed 68% of strength of the base metal but is comparable with it in the state after welding.
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