Types Of Structural Changes Research Articles

Organic changes of anal sphincter in complicated rectal fistulas

Aim. To evaluate the diagnostic significance of structural changes in the anal sphincter (AS) in patients with complex rectal fistulas (CRF).Materials and Methods. This study analyzed the results of examination and surgical treatment of 87 patients with rectal fistulas. Following a comprehensive assessment, the structural changes in the anal sphincter (SCAS) among patients with complex rectal fistulas were classified into several categories. The first subgroup included 16 patients (18.4%) with complex rectal fistulas accompanied by inflammatory infiltration of the anal sphincter (reactive sphincteritis, RS). The second subgroup consisted of 24 patients (27.6%) who exhibited fibrotic changes in the anal sphincter (anal sphincter pectenosis, ASP). The third subgroup comprised 17 patients (19.5%) with complex rectal fistulas and defects (diastasis of AS muscles) in the anal sphincter fibers. The fourth subgroup served as the comparison group, consisting of 30 patients (34.5%) with complex rectal fistulas but without organic changes in the AS.Results and Discussion. The primary complaint among all patients with complex rectal fistulas was the presence of a fistula opening with purulent discharge, although additional symptoms varied depending on the type of structural changes in the AS. The study demonstrated that ultrasound showed a sensitivity of 87%, specificity of 69%, and overall accuracy of 92% in diagnosing rectal fistulas, consistent with data reported by other researchers. On ultrasound, reactive sphincteritis presented as a homogeneous or heterogeneous structure of anal sphincter fibers with varying shapes and sizes, characterized by hyperechogenicity intimately adjacent to fluid accumulations (or intersphincteric localization), filled with contents of varying degrees of echogenicity depending on the stage of inflammation. The ultrasound characteristics of anal sphincter pectenosis (ASP) differed from RS, showing a decrease in sphincter fiber volume and deformation of the AS with retraction of the muscular ring. Defects in the internal sphincter were characterized by varying degrees of hypoechogenicity, with lengths ranging from 0.3 to 1.2 cm, and were more frequently observed along the posterior rectal wall.Conclusions. Complex rectal fistulas are often associated with organic changes in the structure of the anal sphincter, manifesting as reactive sphincteritis, anal sphincter pectenosis, and defects in the muscle fibers of the external anal sphincter. The clinical course of the disease in patients with ASP is influenced by both the type of rectal fistula and the nature and severity of SCAS.

Interactions of gliadins with flavonoids and their glycosides studied with application of FT-Raman spectroscopy

FT-Raman spectroscopy was applied to study interactions between wheat gliadins and three flavonoids and their glycosides. Complexes gliadins-flavonoids/glycosides were extracted from the model wheat dough. As flavonoids were used quercetin, naringenin, hesperetin and their glycosides rutin, naringin, hesperidin in the amount of 0.05%, 0.1% and 0.2%. The analysis of the FT-Raman spectra showed that the tested compounds caused changes in the secondary and tertiary structure of gliadins. In the case of gliadins, these changes concerned mainly α-helices. Quercetin induced a different type of structural changes compared to naringenin and hesperetin, which was probably due to the presence of a double bond on the C ring and an additional OH group on the B ring in the structure of this molecule. On the other hand, the interactions of glycosides with gliadins were affected by the place of attachment of the sugar part in the structure of the glycoside. Flavonoids/glycosides significantly increased the content of disulfide bridges in the g-g-g conformation. Changes in the amino acid microenvironment (tyrosine and tryptophan) indicate the formation of a more ordered structure in gliadins.

Causal clauses as source of sentential complementation: cross-linguistic evidence and methodological issues

Abstract In many languages, causal clause markers can also function as – or are formally identical to – complement markers (e.g., Bulgarian če, Twi se, or Latin quod). This isomorphism is often explained as the result of independent developments from a common source (interrogatives, relativizers, etc.). By contrast, it is also frequently accepted that in some cases the aforementioned identity originates in a type of structural change by which causal clauses are eventually reanalysed as factive complements. However, the nature of the proposed CAUSE > COMPLEMENT development, involving both semantic adjustments and syntactic integration, is not yet fully understood, and it remains unclear how recurrent this phenomenon might be from a cross-linguistic perspective. This article aims to shed light on these questions by analysing diachronic and cross-linguistic data and assessing some of the evidence given for the development of complementation from causal adverbial clauses. The observations reveal significant documentation gaps for postulated models of the emergence of complement clauses and highlight methodological issues that qualify previous explanations about the diachronic relationship between causal and complement clauses.

Сканирующая электронная микроскопия легких крыс при блеомициновом фиброзе

Introduction. Pulmonary fibrosis is a serious lung disease with high risks of mortality and functional impairments. The model of bleomycin-induced pulmonary fibrosis in rodents is one of the most common and frequently used models. Complex methods for analyzing dewaxed tissues enable us to obtain valuable information about morphological, microstructural, and chemical changes in tissues using the existing material, i.e., without conducting separate studies. The purpose of this paper was to identify characteristic morphological changes in a model of bleomycin-induced pulmonary fibrosis, the medication being administered intratracheally, using scanning electron microscopy (SEM) in deparaffinized lung samples. Materials and methods. The experiment includedmale Wistar rats weighing 200–250 g, in which pulmonary fibrosis was modeled by intratracheal administration of bleomycin. After 28 days, the lungs were fixed with perfusion of a 4% solution of neutral buffered formalin through the vena cava until cardiac arrest. The samples were further fixed with 10% buffered formalin for 36 hours, plunged into alcohols, and embedded in paraffin. For SEM, thick 250-μm sections were deparaffinized in xylene and alcohol, saturated with hexamethyldisilazane, and air-dried. After gold sputtering, the samples were viewed and photographed under a JCM-7000 benchtop electron microscope. Results. Light microscopy revealed signs of fibrosis in the lungs of all experimental rats. The fibrosis was local. We distinguished three types of structural changes: 1) slight structural differences from the control animals, 2) inflammation with initial signs of collagen formation, and 3) areas with complete fibrosis. Conclusion. The use of SEM in analyzing thick sections significantly expands the possibilities of studying the lungs in such pathologies as fibrosis and allows one to examine high-resolution surface ultrastructures and identify various inclusions that cause pathological changes seen with X-ray microanalysis. This approach is simple, fast, and low-cost to prepare samples for SEM using existing paraffin blocks and provides more detailed structural information about the development of pulmonary fibrosis. Keywords: scanning electron microscopy, bleomycin fibrosis, rat lungs

Which neurodevelopmental processes continue in humans after birth?

Once we are born, the number and location of nerve cells in most parts of the brain remain unchanged. These types of structural changes are therefore a significant form of flexibility for the neural circuits where they occur. In humans, the postnatal birth of neurons is limited; however, neurons do continue to migrate into some brain regions throughout infancy and even into adolescence. In human infants, multiple migratory pathways deliver interneurons to destinations across the frontal and temporal lobe cortex. Shorter-range migration of excitatory neurons also appears to continue during adolescence, particularly near the amygdala paralaminar nucleus, a region that follows a delayed trajectory of growth from infancy to adulthood. The significance of the timing for when different brain regions recruit new neurons through these methods is unknown; however, both processes of protracted migration and maturation are prominent in humans. Mechanisms like these that reconfigure neuronal circuits are a substrate for critical periods of plasticity and could contribute to distinctive circuit functionality in human brains.

Structural transformations in Cu, Ag, and Au metal nanoclusters.

Finite-temperature structures of Cu, Ag, and Au metal nanoclusters are calculated in the entire temperature range from 0K to melting using a computational methodology that we proposed recently [M. Settem et al., Nanoscale 14, 939 (2022)]. In this method, Harmonic Superposition Approximation (HSA) and Parallel Tempering Molecular Dynamics (PTMD) are combined in a complementary manner. HSA is accurate at low temperatures and fails at higher temperatures. PTMD, on the other hand, effectively samples the high temperature region and melts. This method is used to study the size- and system-dependent competition between various structural motifs of Cu, Ag, and Au nanoclusters in the size range 1-2nm. Results show that there are mainly three types of structural changes in metal nanoclusters, depending on whether a solid-solid transformation occurs. In the first type, the global minimum is the dominant motif in the entire temperature range. In contrast, when a solid-solid transformation occurs, the global minimum transforms either completely to a different motif or partially, resulting in the co-existence of multiple motifs. Finally, nanocluster structures are analyzed to highlight the system-specific differences across the three metals.

THEORETICAL BASICS OF STUDYING STRUCTURAL CHANGES IN THE RESOURCE PROVISION OF THE BUSINESS SECTOR

Topicality. Ukraine is in difficult circumstances related to the military aggression of a neighboring country. These circumstances affected the socio-economic conditions: the fall in the level of GDP, the reduction of production processes, internal and external migration of the population, a decrease in the pace of technological development, a decrease in the number of business entities, a decrease in the capacities of enterprises, an increase in unemployment, a decrease in the welfare and quality of life of the population. Undoubtedly, this led to structural changes in the economy of Ukraine and its regions.Aim and tasks. The purpose of this scientific article is to develop the theoretical foundations of the study of structural changes in resource provision of the entrepreneurial sector. This goal made it possible to formulate the following tasks: define the concept of "resource provision of the entrepreneurial sector"; to improve the classification of structural changes: by levels of management (from the point of view of the types of structural changes and the potential capabilities of the system as a result of overcoming them); to systematize theories of economic growth and smoothing of structural changes in the economy; generalize the principles of overcoming structural changes in resource provision and the ways of their implementation in the economy of Ukraine.Materials and Methods. This study was carried out on the basis of the use of the comparative method, elementary theoretical analysis and synthesis, methods of empirical research, the method of scientific knowledge, classification and analogy, the method of scientific knowledge. Data of the Statistical Service of Ukraine, materials of scientific publications and researches, own scientific developments were also used.Research results. The impact of structural changes on such areas as: socio-societal; spatial and territorial; technological and production; organizational and managerial; foreign economic/international. The changes themselves are considered at the following levels: global, state, regional, branch, local, entrepreneurial (firm), as well as in various spheres of activity (economy, society, resource provision, etc.). The work classifies structural changes by management levels: global (world) changes; national (macroeconomic) changes; regional (territorial) changes; sectorial (industry) changes and entrepreneurial (micro) changes. In addition, structural changes are classified by functional component: technical and technological; institutional; reproductive; territorial and spatial. The main challenges of the Ukrainian economy in peacetime and wartime have been identified. The main methods ("cost-output", structural analysis, portfolio analysis, econometric analysis, cluster analysis, analysis of the dynamics of transactional and transformational costs) and structural change approaches (evolutionary, institutional, synergistic, cybernetic, structural, neoclassical, innovative-technological) are considered. Let's consider the main theories of the growth of the economy of the country and its regions according to the feature of the unification of territories (cumulative growth, the natural occurrence of negative structural changes, the relationship between the occurrence of negative structural changes and economic growth, the regulation of negative structural changes, technological growth, the impact of innovative development on negative structural changes).Conclusions. The effectiveness and efficiency of business activity consists in the identification of negative structural changes, the development of a methodological apparatus for their elimination, the regulatory and legal provision of these processes, the development of regulatory mechanisms, the identification of responsible persons and a clear communication process between them. Thus, the key to overcoming negative structural changes in the economy can be: strengthening of state management and regulation; balancing market self-regulation at the national, regional and local levels; state initiative and participation in regional transformation processes; development of theoretical and methodological approaches and principles to overcome negative shifts in the development of the country and its regions.This scientific article was carried out within the framework of the NDR "Mechanisms of structural transformation of the entrepreneurial sector of Ukraine on the basis of resilient economic development" (code: 3.1.8.84/B).

Brain morphometric changes in fibromyalgia and the impact of psychometric and clinical factors: a volumetric and diffusion-tensor imaging study

BackgroundPrevious studies have repeatedly found distinct brain morphometric changes in patients with fibromyalgia (FM), mainly affecting gray and white matter abnormalities in areas related to sensory and affective pain processing. However, few studies have thus far linked different types of structural changes and not much is known about behavioral and clinical determinants that might influence the emergence and progression of such changes.MethodsWe used voxel-based morphometry (VBM) and diffusion-tensor imaging (DTI) to detect regional patterns of (micro)structural gray (GM) and white matter (WM) alterations in 23 patients with FM compared to 21 healthy controls (HC), while considering the influence of demographic, psychometric, and clinical variables (age, symptom severity, pain duration, heat pain threshold, depression scores).ResultsVBM and DTI revealed striking patterns of brain morphometric changes in FM patients. Bilateral middle temporal gyrus (MTG), parahippocampal gyrus, left dorsal anterior cingulate cortex (dACC), right putamen, right caudate nucleus, and left dorsolateral prefrontal cortex (DLPFC) showed significantly decreased GM volumes. In contrast, increased GM volume was observed in bilateral cerebellum and left thalamus. Beyond that, patients displayed microstructural changes of WM connectivity within the medial lemniscus, corpus callosum, and tracts surrounding and connecting the thalamus. Sensory-discriminative aspects of pain (pain severity, pain thresholds) primarily showed negative correlations with GM within bilateral putamen, pallidum, right midcingulate cortex (MCC), and multiple thalamic substructures, whereas the chronicity of pain was negatively correlated with GM volumes within right insular cortex and left rolandic operculum. Affective-motivational aspects of pain (depressive mood, general activity) were related to GM and FA values within bilateral putamen and thalamus.ConclusionsOur results suggest a variety of distinct structural brain changes in FM, particularly affecting areas involved in pain and emotion processing such as the thalamus, putamen, and insula.

Do the effects of substrate complexity influence the emergence position of microalgae on streams?

The spatial distribution of stream algae on substrates may be molded by the spatial arrangement of surface features. The variation of surface complexity on stream bottom may represent the availability of suitable areas for algal growth. Here we showed that different levels of surface complexity, at the scale used, did not affect the abundance of microalgae, however, we did note that specific areas of substrates seem to be more appropriate for initial algal establishment. Our results indicate that scale is fundamental to assess the effects of substrate on spatial distribution of benthic lotic microalgae and this may help us better understand how the different types of structural changes created by human activities in streams can affect algal colonization.

Different types of structural changes in the sacroiliac joints in axial spondyloarthritis: how important are joint shape variations?

Different types of structural changes in the sacroiliac joints in axial spondyloarthritis: how important are joint shape variations?

Testing for time-varying factor loadings in high-dimensional factor models

This paper proposes a test for structural changes in factor loadings in high-dimensional factor models under weak serial and cross-sectional dependence. The test is an aggregate statistic in the form of the maximum of the variable-specific statistics whose asymptotic null distribution and local power property are studied. Two approaches including extreme value theory and Bonferroni correction are adopted to compute the critical values of the aggregate test statistic. Monte Carlo simulations reveal the non-trivial power of the proposed test against various types of structural changes, including abrupt changes, nonrandom smooth changes, random-walk variations and stationary variations. Additionally, our test can be more powerful than some alternative tests in the considered scenarios. The usefulness of the test is illustrated by an empirical application to Stock and Watson’s U.S. data set.

Quasi-maximum likelihood estimation of break point in high-dimensional factor models

This paper proposes a quasi-maximum likelihood (QML) estimator of the break point for large-dimensional factor models with a single structural break in the factor loading matrix. We show that the QML estimator is consistent for the true break point when the covariance matrix of the pre- or post-break factor loading (or both) is singular. Consistency here means that the deviation of the estimated break date from the true break date k0 converges to zero as the sample size grows. This is a much stronger result than the break fraction kˆ/T being T-consistent (super-consistent) for k0/T. Also, singularity occurs for most types of structural changes, except for a rotational change. Even for a rotational change, the QML estimator is still T-consistent in terms of the break fraction. Simulation results confirm the theoretical properties of our estimator, and it significantly outperforms existing estimators for change points in factor models.

High-strength glass-ceramic from ZABS system modified with transition metal oxide

The designed glass-ceramic from the ZABS (ZnO-Al2O3-B2O3-SiO2) glass-forming system were used for the experiment. The main purpose of this study was to investigate the effect of copper oxide on the structural and mechanical properties of a glass-ceramic, with willemite as the main crystalline phase. Generally, transition metal (TM) oxides significantly affect the crystallisation characteristics, subsequently influencing the thermal behaviour of the glass-ceramics. Both samples were tested to determine the type of structural changes that occur after the introduction of the modifier – copper oxide. The type of deformations occurring during scratch-test, were also checked in terms of plastic flow, structural densification and mechanical properties (Young's modulus and hardness).

THE METHOD OF STRUCTURAL ADJUSTMENT OF NEURAL NETWORK MODELS TO ENSURE INTERPRETATION

Context. The problem of structural modification of pre-synthesized models based on artificial neural networks to ensure the property of interpretation when working with big data is considered. The object of the study is the process of structural modification of artificial neural networks using adaptive mechanisms.
 Objective of the work is to develop a method for structural modification of neural networks to increase their speed and reduce resource consumption when processing big data.
 Method. A method of structural adjustment of neural networks based on adaptive mechanisms borrowed from neuroevolutionary synthesis methods is proposed. At the beginning, the method uses a system of indicators to evaluate the existing structure of an artificial neural network. The assessment is based on the structural features of neuromodels. Then the obtained indicator estimates are compared with the criteria values for choosing the type of structural changes. Variants of mutational changes from the group of methods of neuroevolutionary modification of the topology and weights of the neural network are used as variants of structural change. The method allows to reduce the resource intensity during the operation of neuromodels, by accelerating the processing of big data, which expands the field of practical application of artificial neural networks.
 Results. The developed method is implemented and investigated by the example of using a recurrent artificial network of the long short-term memory type when solving the classification problem. The use of the developed method allowed speed up of the neuromodel with a test sample by 25.05%, depending on the computing resources used.
 Conclusions. The conducted experiments confirmed the operability of the proposed mathematical software and allow us to recommend it for use in practice in the structural adjustment of pre-synthesized neuromodels for further solving problems of diagnosis, forecasting, evaluation and pattern recognition using big data. The prospects for further research may consist in a more fine-tuning of the indicator system to determine the connections encoding noisy data in order to further improve the accuracy of models based on neural networks.

A nonparametric change detection approach in social networks

AbstractA network provides powerful means of representing relationships between entities in complex physical, biological, cyber, and social systems. Any phenomena in those areas may be realized as changes in the structure of the associated networks. Hence, change detection in dynamic networks is an important problem in many areas, such as fraud detection, cyber intrusion detection, and health care monitoring. This article proposes a new methodology for monitoring dynamic networks for quick detection of structural changes in network streams and also estimating the location of the change‐point. The proposed methodology utilizes the eigenvalues for the adjacency matrices of network snapshots and employs a nonparametric hypothesis to test if the distribution of the eigenvalues for the current snapshot is different from those of the previous ones along a sliding window of reference networks. The statistic of the nonparametric test, energy distance among eigenvalues, is monitored using a one‐sided exponentially weighted moving average control chart. Then, after an anomaly detection signal from the monitoring scheme, eigenvalues for the snapshots are employed to calculate the energy statistic at various time steps to locate the change‐point. The proposed method is intended to detect two types of structural changes in the networks: (1) change in the communication rates among individuals and (2) change in the community structure of the network. The proposed methodology is applied to both simulated and real‐world data. Results indicate that the proposed methodology provides a reliable tool for monitoring networks streams and also estimating change‐points locations for precise assessing of the networks under investigation.

Atomic‐scale mechanisms of densification in cold‐compressed borosilicate glasses

AbstractKnowledge of the underlying structural response during deformation processes is essential for understanding the macroscopic mechanical response of glass. Here we present results from cold compression‐decompression molecular dynamics (MD) simulations of two multicomponent borosilicate glasses, Borofloat®33 (Boro33) and N‐BK7® (N‐BK7). Our results suggest that the densification of these two borosilicate glasses involves different types of structural changes. The fraction of permanent densification can be correlated to the change in intermediate‐range structure. By performing Voronoi analysis, we quantify the contributions to densification from different cation types in these two multicomponent borosilicate glasses, finding that 3‐coordinated cations facilitate the densification process. Higher‐coordinated cations are relatively stable and can even show a slight expansion in their Voronoi volume.

Development of High Performance C-Rich a-SiC Semiconductors with Narrow-Optical Gap By Control of Its Phase Structure

1. Introduction For the expansion of application fields (ex. tailor-made photocatalysts and high-efficiency laser) of semiconductor, novel semiconductor materials with variable optical gaps in the range from 1.2 to 3.0 eV is necessary to be developed. The promising candidate of these semiconductor is carbon-rich amorphous silicon-carbon alloy (C-rich a-SiC).[1] The optical gaps (Eog) of C-rich a-SiC can be changed from 1.2 to 2.7 eV by changing the Si/C ratio. Hetero-junction solar cell comprising N-doped C-rich a-SiC with Eog = 2.7 eV and p-type Si have been reported to show the function of photon to electron conversion.[2] However, solar cells comprising N-doped C-rich a-SiC with Eog from 1.2 to 1.7 eV showed extremely lower conversion efficiencies. Therefore, all of these C-rich a-SiC with Eog from 1.2 to 2.7 eV may not be applied to photoelectronic devices. The objective of this study is to realize C-rich a-SiC with lower Eog (frim 1.2 to 1.7 eV) that have higher semiconductor property and are able to be applied to photoelectronic devices. a-SiC has a multiphase structure in which amorphous Si-C network (Si:C = x:1-x), sp2-hybridized carbon cluster (sp 2 clusters), and silicon-like clusters (Si-cluster) coexist. It has been reported that excess sp2 cluster worked as a recombination center of photoexcited carries. It results in the degradation of efficiencies of photon to electron conversion. In order to realize C-rich a-SiC with lower Eog and higher photon to electron conversion efficiency, the synthesis method that can enhance of ratio of C/Si in amorphous Si-C network and suppress the formation of sp 2 clusters in C-rich a-SiC is necessary to be developed. In this study, CVD synthesis using high-frequency and lower power r. f. plasma was tried to be adopted to induce two types of structural change at C-rich a-SiC. High-frequency and lower power r. f. plasma can avoid the formation of sp 2 clusters in C-rich a-SiC. It results in the semiconductor materials with lower Eog and higher photon to electron conversion efficiency.2. Experimental Nitrogen-doped C-rich a-SiC thin films were synthesized by radio frequency plasma enhanced chemical vapor deposition system (RF-PeCVD) (13.56 MHz, SAMCO Co., Ltd. Model BPD-1) using tetramethylsilane, 1,1,3,3-tetrametyldisilazane and n-hexanes as source materials. C-rich a-SiC thin films were deposited on glass plate and boron-doped silicon (100) substrate (resistivity of 2 W cm) after an in-situ sputter cleaning with argon ions. Substrate temperature was kept at 160 degree C during CVD deposition. The frequency of r.f. power supply was set at 60 MHz and r.f power were changed from 5 to 26 W. The deposition time was 80 minutes. Transmission spectra of N-doped C-rich a-SiC deposited on glass substrates were examined by UV-Vis spectrophotometer (JASCO Co., Ltd. V-670). The performance of heterojunction solar cells was investigated by current-voltage (I-V) measurement (KEYSIGHT, B2901A) with simulated AM 1.5 sunlight (ASAHI SPECTRA, HAL-320). 3. Results and Discussion Eog estimated from transmission spectra (Fig. 1) of resulting N-doped C-rich a-SiC were found to be in the range from 1.40 to 2.96 eV, as shown in Table 1. Eog was able to be controlled to lower value (1.4 eV) thorough the change of the S/C ratios in C-rich a-SiC (by changing the volume ratio of n-hexane in source materials). All hetero-junction solar cells comprising N-doped C-rich a-SiC with various Eog and p-type Si crystal were confirmed to show the function of photon-to electron conversion (Table 1). The improvement of function of photon to electron conversion at C-rich a-SiC with lower Eog (ca. 1.4 eV) might be caused by the suppression of the recombination of photo-exited electrons and holes. In Figure 1, the absorption peak of sp 2 clusters was observed at 1.1 eV and was clearly separated from the absorption peak of amorphous Si-C network (observed at 2.6 eV). The intensity decrease and peak shift to lower energy side of the absorption of sp 2 clusters in Fig. 1 indicates the decrease of the amount of sp 2 clusters and the enlargement of size of sp 2 clusters. These structural change might cause the suppression of recombination of photo-carriers. The relation between Eog and open circuit voltage of solar cell was consistent with estimated value from electronic structure of C-rich a-SiC. It was summarized that the development of C-rich a-SiC semiconductors with lower Eog (in the range from 1.4 to 1.7 eV) that are able to be applied to photo-electronic devices was successfully achieved. 4.

Molecular-Dynamics Simulation of the Interaction Processes of Pulsed Ion Beams with Metals

The molecular-dynamics method is used to model the interaction processes of pulsed ion beams with metal targets. The main parameters of a pulsed ion beam interacting with a target are the ion energy, pulse duration, and charge density per unit area of the target. Using averaged values of these parameters of ion beams published for various types of accelerators, a numerical study of the dependence of the dynamics of thermal and structural processes in irradiated targets upon a change in the size and heterogeneity of the structure is performed. Simulation of the irradiation processes and estimates of the distribution of beam ions in the volume are carried out in the range of beam ion energies of 1–2 keV using the concept of a shock wave. The results are important for developing the model of a pulsed ion beam and classifying the types of structural changes in the irradiated material depending on the model parameters.

Chemical Mutagenesis and Cytogenetic Chromosomal Abnormalities in a Population Living in the Aral Sea region

AIM: The article presents the results of a study of chromosomal mutations in residents living in the Aral Sea disaster zone, using the example of the city of Aralsk.
 METHODS: The article identifies the level of chromosomal aberrations (CA) in the surveyed population and identifies the leading type of aberrations in this region.
 RESULTS: Researches have shown that the main types of structural changes were chromatid breaks and single fragments of chromosomes. The results showed that in the study population, the microelement status indicates an imbalance of microelements. A correlation analysis showed a relationship between the nickel content in the blood and the increase in CAs. Furthermore, researches show a hypothesis about the pathogenesis mechanism of the formation of CAs.
 CONCLUSION: Thus, the article provides information on chromosomal mutations during chemical mutagenesis.

Criteria for the Selection of Diagnostic Signs of Chronic Pancreatitis with Obstruction of the Main Pancreatic Duct

Introduction. Clinical outcomes of surgery for patients with chronic pancreatitis (CP), considering low rates of 10-year survival, are often unsatisfying for surgeons. Due to the absence of common diagnostic criteria, especially at an early stage of the disease, patients of young and working age undergo surgery at different periods and with different methods. The development of optimal criteria for the selection of diagnostic signs of chronic pancreatitis will improve treatment outcomes.The aim of the study is 1) to perform a comparative assessment of the informative value of methods that specify diagnostics of CP with obstruction of the main pancreatic duct; 2) to develop criteria for the selection of diagnostic signs to highlight the main types of structural changes in the pancreas in chronic pancreatitis with obstruction of the main pancreatic duct.Materials and methods. The study included radiological findings of 231 patients with CP with obstruction of the main pancreatic duct operated from 1996 to 2018 in Omsk regional surgical hospital. X-ray investigations were performed in 120 patients, ultrasound investigations were performed in 231 patients, multislice spiral computed tomography (MSCT) was performed in 226 patients, MRI was performed in 18 patients, endoscopic retrograde cholangiopancreatography (ERCP) was performed in 22 patients and angiography was performed in 5 patients. All patients were divided into two groups: control (n ​​= 88, until 2008) and case (n = 143, after 2008), where new methods of surgery were used and the structure of the applied diagnostic methods has been changed.Results. Ultrasound sensitivity was 74.5%, fistulography/virsungography sensitivity was 80%, MSCT sensitivity was 97.8%, MRI sensitivity was 88.9% and ERPC sensitivity was 95.5%. The use of invasive diagnostic methods in the main group of patients was minimized with the priority of MSCT. The main criteria for the selection of diagnostic signs of CP were determined as follows: obstruction of the main pancreatic duct (with localization at the level of the pancreatic head exclusively or along its entire length), dilatation of the main pancreatic duct (more than 3 mm), local damage to the pancreatic head with an increase in its size over 32 mm, cystic formations (more than 5 mm) in the projection of any part of the pancreas. The main types of structural changes in the pancreas were identified as follows: 1. CP with obstruction of the main pancreatic duct at the level of the pancreatic head exclusively; 2. CP with obstruction of the main pancreatic duct along its entire length with an increase in the size of the pancreatic head; 3. CP with obstruction of the main pancreatic duct along its entire length without an increase in the size of the pancreatic head.Conclusion. 1) MSCT has the highest sensitivity in CP diagnostics (98.6%). MRI (Magnetic Resonance Cholangiopancreatography (MRCP)) complements MSCT and replaces it in case of patients intolerance to contrast media. Indications for ERCP should be minimized. 2) The designed criteria for the selection of diagnostic signs of CP will optimize diagnostics of chronic pancreatitis with obstruction of the main pancreatic duct and highlight the main types of structural changes in the pancreas, the fact being important for validation of surgical treatment methods and techniques.