2,602 research outputs found

    Computer simulation of field ion images of nanoporous structure in the irradiated materials

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    Computer simulation and interpretation of field ion microscopy images of ion irradiated platinum are discussed. Field ion microscopy technique provides direct precise atomic scale investigation of crystal lattice defects of atomically pure surface of material; at the same time it allows to analyze the structural defects in volume by controlled and sequential removal of surface atoms by electric field. Defects identification includes the following steps: at the first stage the type of crystalline structure and spatial orientation of crystallographic directions were determined. Thus, we obtain the data about exact position of all atoms of the given volume, i.e. the model image of an ideal crystal. At the second stage, the ion image was processed used the program to obtain the data about real arrangement of atoms of the investigated sample. At the third stage the program compares these two data sets, with a split-hair accuracy revealing a site of all defects in a material. Results of the quantitative analysis show that shape of nanopores are spherical or cylindrical, diameter on nanopores was varied from 1 to 5 run, their depth was fond to be from 1 to 9 nm. It was observed that nearly 40% of nanopores are concentrated in the subsurface layer 10 nm thick, the concentration of nanopores decreased linearly with the distance from the irradiated surface

    Mathematical Models of Video-Sequences of Digital Half-Tone Images

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    This chapter is devoted to Mathematical Models (MM) of Digital Half-Tone Images (DHTI) and their video-sequences presented as causal multi-dimensional Markov Processes (MP) on discrete meshes. The difficulties of MM development for DHTI video-sequences of Markov type are shown. These difficulties are related to the enormous volume of computational operations required for their realization. The method of MM-DHTI construction and their statistically correlated video-sequences on the basis of the causal multi-dimensional multi-value MM is described in detail. Realization of such operations is not computationally intensive; Markov models from the second to fourth order demonstrate this. The proposed method is especially effective when DHTI is represented by low-bit (4-8 bits) binary numbers

    Development of Nonlinear Filtering Algorithms of Digital Half-Tone Images

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    This chapter is devoted to solving the problem of algorithms and structures investigations for Radio Receiver Devices (RRD) with the aim of the nonlinear filtering of Digital Half-Tone Images (DHTI) representing the discrete-time and discrete-value random Markovian process with a number of states greater than two. At that, it is assumed that each value of the DHTI element is represented by the binary g-bit number, whose bits are transmitted via digital communication links in the presence of Additive White Gaussian Noise (AWGN). The authors present the qualitative analysis of the optimal DHTI filtering algorithm. The noise immunity of the optimal radio receiver device for the DHTI filtering with varying quantization and dimension levels is investigated

    The redox transformations and nucleophilic replacements as possible metabolic reactions of the drug “Triazaverin”. The chemical modeling of the metabolic processes

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    As a model of metabolic transformations of antiviral drug “Triazaverin” and its analogues‑2-alkylthio‑6-nitro‑1,2,4-triazolo[5,1-c][1,2,4]triazine‑7-ones 1a-d examined the oxidation of alkylthio groups to the corresponding sulfoxides 2a-d and sulfones 3a-d, as well as the process of nucleophilic substitution sulfonyloxy group of cysteine and cysteamine with the formation of compounds 5 and 6

    Role of direct exchange and Dzyaloshinskii-Moriya interactions in magnetic properties of graphene derivatives: C2_2F and C2_2H

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    According to the Lieb's theorem the ferromagnetic interaction in graphene-based materials with bipartite lattice is a result of disbalance between the number of sites available for pzp_z electrons in different sublattices. Here, we report on another mechanism of the ferromagnetism in functionalized graphene that is the direct exchange interaction between spin orbitals. By the example of the single-side semihydrogenated (C2_2H) and semifluorinated (C2_2F) graphene we show that such a coupling can partially or even fully compensate antiferromagnetic character of indirect exchange interactions reported earlier [Phys. Rev. B {\bf 88}, 081405(R) (2013)]. As a result, C2_2H is found to be a two-dimensional material with the isotropic ferromagnetic interaction and negligibly small magnetic anisotropy, which prevents the formation of the long-range magnetic order at finite temperature in accordance with the Mermin-Wagner theorem. This gives a rare example of a system where direct exchange interactions play a crucial role in determining a magnetic structure. In turn, C2_2F is found to be at the threshold of the antiferromagnetic-ferromagnetic instability, which in combination with the Dzyaloshinskii-Moriya interaction can lead to a skyrmion state.Comment: 10 page

    Outpatient management of patients with peripheral artery disease by cardiologists or surgeons: influence on the prognosis and prevalence of surgical interventions

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    Highlights. The study shows for the first time that during the three-year follow-up of patients with diseases of the arteries of the lower extremities in the observation groups of a general surgeon and a cardiologist, adverse events (myocardial infarction, stroke, amputation, disability) and deaths occurred more often in a surgeon than a cardiologist. The study proves the correctness and real benefit of such an approach with the involvement of a cardiologist to the outpatient stage of management of a complex cohort of patients with atherosclerosis of the vessels of the lower extremities.Aim. To study the effect the outpatient observation of patients with peripheral arteries disease (PAD) by cardiologists and surgeons has on timing and prevalence of reconstructive surgery and the prognosis of patients. Methods We analyzed the data on 585 PAD patients who underwent outpatient observation from 2010 to 2017, dividing them into 2 groups. The first group (131 patients) managed by an surgeon; the second (454 patients) managed by a cardiologist. Since the groups were not comparable in terms of the initial parameters, the comparability of patients in the groups (observation by a surgeon or by a cardiologist) was achieved using pseudorandomization. The follow-up period was three years; we assessed the incidence of deaths, adverse events, and the prevalence of reconstructive operations.Results. During a three-year follow-up the 1st group, compared with the 2nd, had more deaths in general (p<0.001), death from cardiac causes (p = 0.045), from stroke (p><0.001), as well as the total number of adverse events (p><0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients. Conclusion Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries. Keywords Peripheral atherosclerosis • Outpatient follow-up • Optimal drug therapy • Reconstructive surgery>˂ 0.001), death from cardiac causes (p = 0.045), from stroke (p˂ 0.001), as well as the total number of adverse events (p˂ 0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients.Conclusion. Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries.Highlights. The study shows for the first time that during the three-year follow-up of patients with diseases of the arteries of the lower extremities in the observation groups of a general surgeon and a cardiologist, adverse events (myocardial infarction, stroke, amputation, disability) and deaths occurred more often in a surgeon than a cardiologist. The study proves the correctness and real benefit of such an approach with the involvement of a cardiologist to the outpatient stage of management of a complex cohort of patients with atherosclerosis of the vessels of the lower extremities.Aim. To study the effect the outpatient observation of patients with peripheral arteries disease (PAD) by cardiologists and surgeons has on timing and prevalence of reconstructive surgery and the prognosis of patients. Methods We analyzed the data on 585 PAD patients who underwent outpatient observation from 2010 to 2017, dividing them into 2 groups. The first group (131 patients) managed by an surgeon; the second (454 patients) managed by a cardiologist. Since the groups were not comparable in terms of the initial parameters, the comparability of patients in the groups (observation by a surgeon or by a cardiologist) was achieved using pseudorandomization. The follow-up period was three years; we assessed the incidence of deaths, adverse events, and the prevalence of reconstructive operations.Results. During a three-year follow-up the 1st group, compared with the 2nd, had more deaths in general (p<0.001), death from cardiac causes (p = 0.045), from stroke (p><0.001), as well as the total number of adverse events (p><0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients. Conclusion Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries. Keywords Peripheral atherosclerosis • Outpatient follow-up • Optimal drug therapy • Reconstructive surgery>˂ 0.001), death from cardiac causes (p = 0.045), from stroke (p˂ 0.001), as well as the total number of adverse events (p˂ 0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients.Conclusion. Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries

    Model of Economic Phenomenon

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    As is known, economic phenomena represent the most important part of the subject of economic science. However, modern economic theory avoids a clear definition of this category. Thus, it remains unclear what is economic phenomena, and thus the economy is in its essence as suc
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