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Circuit solutions for physically unclonable functions (PUF) of a ring oscillator (RO) implementation for the purposes of digital devices identification, cryptographic keys and random numbers generation are considered. The effectiveness using configurable ROs (CROs) in PUF circuits is based not only on reducing of the hardware overhead of traditional RO PUFs, but also on the generation of output signals with unique frequencies, close in value in a case of the FPGA implementation. The proposed modification of the basic scheme of the CRO PUF, based on the XOR2 logic gates as controlled delay elements, allows to use a full set of input challenges instead of the basic scheme. It is shown that the delay value depends not only on the challenge, but also on the interconnect configuration of the structural elements of the CRO circuit. A time model of the modified CRO PUF is proposed, which analytically proves the influence of interconnects on the frequency of the generated signal, which was experimentally confirmed using the Xilinx Zynq-7000 FPGA. Based on this result, a new structure of PUF CRO with controlled interconnections is proposed.

The aim of this paper is to assess the logistics potential to ensure the resilience of the economic system of Ukraine in the face of global challenges. The methods used in the study include: structural-dynamic, determinological, correlation analysis, index method, graphical and cartographic methods. The calculations were based on open data from analytical studies on the development of transport and logistics, as well as data from the State Statistics Service of Ukraine. The results of the study confirmed the hypothesis that high logistics potential, which is determined by the effectiveness of customs and border control, the quality of trade and transport infrastructure, the ease of organization of delivery, and the quality of logistics services, is the driver of the resilience of socio-economic systems of countries. The reduction of the logistical potential of the economic system of Ukraine in the conditions of a full-scale war is shown. This decrease resulted from blocked operation of a number of logistics routes and branches of the transport and logistics sphere and destroyed transport infrastructure objects as a result of hostilities and missile attacks.A change in the vector of export-import flows and their reorientation by means of transport was noted. Drivers of strengthening the logistics potential of the Ukrainian economic system are the transformation of the transport and logistics system, deepening cooperation with neighboring countries, systematic state support for the development of freight transportation by rail, compliance with European standards, and creation of Ukrzaliznytsia’s own freight carrier company that will work outside Ukraine. AcknowledgmentThis study was carried out within the framework of the international project “Increasing the capacity of freight transportation infrastructure on EU-Ukraine borders” (№ 22220189) implemented under the Visegrad Grant+ Programme.

The article considers the range of subjects related to Mykola Rigelman’s travels to European countries in the 40-60s of the 19th century. The travelogues of this public figure and historian became the basis of our scientific research. They are characterized by subjective nature of the descriptions, the lack of clear structure, and inconsistency in the presentation of the material (for example, detailed representation of the German lands and only brief mentions of his stay in France). However, travelogues contain depictions of everyday life that are difficult or impossible to recreate with the help of other sources. The study found that the traveler was attracted not only to material culture, but also to customs, traditions, and worldview beliefs of people of different countries. It has been revealed that Mykola Rigelman focused on several aspects related to urban space, in particular, general descriptions of landscapes, features of buildings, architectural monuments, mainly of religious significance. Certain problems that were common to both European and Ukrainian cities, such as dirty streets and, at times, the decrepit housing, also attract our attention. Under the influence of imperial ideology and myths, the traveller constantly, often skeptically, compared life in European countries to everyday life in St. Petersburg, and pinpointing negative attitudes, especially those of Germans towards the Russian Empire. Describing his stay abroad, Mykola Rigelman did not limit himself to documenting what he saw and heard. He used historical and ethnographic information about the regions he visited, borrowed from European literature or stories of his compatriots and fellow travelers.

Purpose. The article aims to identify the relationship between migration (in the context of two channels – (1) human resource outflows and (2) remittance inflow) in rural areas and the economic development; justification of measures of preserving rural human resources in rural areas in Ukraine. Methodology / approach. The methodological tools of the study are the construction of lag econometric models that allow identifying the influence of migration flows on key parameters of economic development, as well as the calculation of elasticity coefficients. Results. It is determined that high international migration in Ukraine, especially from territories with a lower quality of life, remote from regional centers, leads to increase human resource outflow in rural areas, which accelerates the rate of their socio-economic degradation and extinction, respectively, does not contribute to balanced spatial development. The positive impact of migration on economic development has been identified, in particular, migration contributes to improving the financial well-being of households, is an instrument for accumulating investment capital and savings, developing small businesses, and enhancing financial inclusion. It is proved that to preserve the human resources of rural areas in Ukraine, it is necessary to implement a proactive policy aimed at balancing the labour market of communities, simplifying the principles of conducting and reducing the risks of small business, increasing the young re-emigration, improving investment capital, increasing the competitiveness of the educational sphere at the local level. Originality / scientific novelty. A new scientific and methodological approach to assessing the dependence of the parameters of development of rural areas on migration processes due to two channels – human resources and remittance has been developed, complementary analysis of which makes it possible to identify the complex impact of migration on the socio-economic development of territories, optimal and critical volumes of migration according to various structural characteristics, migration gaps in the development of the economic system and social spheres of rural areas depending on the level of migration activity and the effectiveness of using the potential of remittance. Practical value / implications. The practical significance of the research results lies in the development of tools for forecasting and planning the state policy of preserving human resources of rural areas in Ukraine, depending on migration aspirations and the purposefulness of remittance.

A new family of symmetrical fluorene derivatives with different types of substituents attached to the C-2 and C-7 positions of the fluorene core synthesized by the Sonogashira coupling reactions is reported. The electronic structures and the properties of the compounds investigated by means of photoelectron emission spectroscopy, UV–Vis absorption and photoluminescent spectroscopy as well as by DFT and TD-DFT theoretical calculations are discussed. It is shown that the nature of substituents influences the π-conjugation of the molecules. No intermolecular charge transfer within the investigated wavelength range is observed. The applicability of the synthesized compounds in organic light-emitting diodes (OLEDs) based on exciplex emission is demonstrated. The advanced co-deposition technique with the tuned OLED architecture was applied and resulted in improved OLED parameters.

Quarantine measures in connection to the COVID-19 pandemic challenged the education system in Ukraine, like the education systems of other countries. This manifested over the course of three years in an increased need to develop distance learning online. Also, teacher ability to use digital tools, such as information communication technology (ICT), for instruction online is crucial in wartime circumstances in Ukraine. We describe the effects of school lockdown on teachers in Ukraine and how this affected teacher abilities to use distance instruction online in wartime circumstances. Drawing on a large-scale survey of 54,254 educators conducted in January-February 2022, we report on challenges and needs identified by teachers in Ukraine. The survey collected responses from teachers and other categories of educators. Our analysis of survey findings focus on key challenges and needs of teachers and schools during the COVID-19 quarantine. Respondents identified the following challenges: (1) lacking access to ICT equipment; (2) lacking access to stable high-speed internet; (3) an insufficient level of knowledge and skills in using ICTs ("digital competence"). The study on which this article reports outlined possibilities for the professional development of teachers in Ukraine, complemented with a teacher self-assessment of digital competence. The findings demonstrate that methods for organising online education in wartime circumstances in Ukraine benefit from the active interaction of all participants in the education process, their adaptability to changing learning conditions, continued communication about needs, notably teacher abilities to use ICT, and the ICT capacity of institutions.

The study of geographical crops is relevant because they are one of the reliable tools for identifying possible scenarios for the response of forest woody plant species to climate change. The purpose of the study of geographical crops of Scots pine established in 1981 in the Kyiv Oblast was to compare the growth and productivity of provenances in different age periods, determine the optimal time for early and final diagnosis of their ranking, and model the relationship between the growth and survivability indicators of provenances with climatic and other environmental variables at the age of 21, 32, and 37 years. The ANOVA method established a statistically significant influence of the geographical origin of seeds on the growth of geographical crops. At the age of 37, the capacity for survival varies from 25% (Lviv provenance) to 36.2% (Chernihiv provenance). At this age, populations from Lviv, Kyiv, and Cherkasy oblasts are characterised by the highest height. According to the intensity of radial growth, these same provenances are distinguished, as well as variants from Volyn and Luhansk. In terms of the stock of stem wood, the best is provenance from the Chernihiv Oblast. Stabilisation of the ranks of provenances in terms of survivability, growth, and productivity is observed only after 21 years. It is assumed that the most accurate assessment of the growth and condition of Scots pine provenances can be obtained at an age that corresponds to a third or a half of the age of the main felling. The trend of clinal variability in the survival of provenances and the average diameter of their trunks along the geographical (latitudinal) and ecological (temperature) gradients is revealed. The study results can be used to update the current forest-seed zoning of Ukraine

This article discusses the issue of studying the parameters of the bounce of electrical contacts of switches in digital systems. Digital circuits of bounce analyzer are described. The results of experimental studies of the behavior of electrical contacts of various buttons and switches are presented. It is shown that various electric switches have random and unique characteristics, which can be used to solve the problems of random numbers generating, identifying of digital devices and user’s authentication. Prototyping of the proposed circuits was carried out on Digilent ZYBO Z7-10 debug boards, digital circuits were designed in VHDL for the Xilinx Zynq-7000 FPGA chip.

Stable economic progress and upward dynamics of economic growth in the regions depend on their level of security and ability to withstand adverse macroeconomic and other shocks, as well as the state of affairs in which risks cannot be transformed into threats and dangers. The study aims to assess the causal nexus and the level of sensitivity of regional economic growth components to changes in financial resilience determinants. The research methods include systemic and structural analyses (building an information and analytical model for studying financial resilience), Granger test (identifying causal relationships between the variables under study), risk theory (studying the nature of fluctuations), and spatial and temporal approach. Data from the regions (oblasts) of Ukraine between 2015 and 2021 form the informational and analytical basis of the study. The paper reveals that the targeted use of transfers for socio-economic progress, increasing investment capacity, and bolstering financial and budgetary autonomy through increasing local budget revenues are the dominant financial determinants of regional economic growth. The results show that the most dominant causal nexus exists between (1) budgetary efficiency, interest rates on consumer/mortgage loans, and SME development, (2) the volume of loans/deposits and labor market efficiency and SME development, and (3) innovation development and foreign economic cooperation. Intensification of investment activity is crucial for ensuring real changes in the economic structure of all regions, particularly outsiders, accelerating transformation processes, mitigating regional economic divergence, and increasing competitiveness. AcknowledgmentsThe study was conducted within the framework of the “Financial Determinants of Ensuring Economic Growth of Regions and Territorial Communities based on Behavioral Economics” project (№ 2020.02/0215) funded by the National Research Foundation of Ukraine (Competition “Support for Research of Leading and Young Scientists”).

The problem of constructing a new class of physically unclonable functions (PUF) based on a controlled ring oscillator (CRO) has beeb solved. The relevance of the creation of CROPUF is associated with the active development of physical cryptography used for the purposes of identifying electronic products and generating cryptographic keys. It is shown that classical physically unclonable functions based on ring oscillators (ROPUF) are characterized by large hardware redundancy due to the need to implement a large number of ROs, since each bit of the response requires an independent pair of real ROs. At the same time ROPUFs are characterized by better statistical properties compared to PUFs of the arbiter type and do not require ideal symmetry and identity of implemented ROs. As an alternative to ROPUF, a new class of physically unclonable functions is proposed, namely, CROPUF, which uses controlled ring oscillators based on controlling the frequency of generated pulses without changing the functionality and structure of the oscillator. An important advantage of the CRO is a possibility of implementing on its basis a set of ROs, the number of which reaches 2m, where m is the number of stages of the oscillator, and each of them is determined by the submitted request. The three alternative structures for the proposed PUF, namely CROPUF1, CROPUF2 and CROPUF3 are considered. Their main advantages and disadvantages are shown, including in the case of two implementation options, namely on programmed logic (FPGA) and arbitrary logic (ASIC). As a basic option for implementation on FPGA, CROPUF2 is considered less prone to inter-chip and, more importantly, intra-chip dependence caused by the technological features of the production process. Practical studies were carried out by implementing CROPUF2 on modern FPGAs, evaluating its performance and its main characteristics. The operability of a new class of PUFs when implemented on programmable logic, as well as high rates of their main statistical characteristics, has been experimentally confirmed.

Physically unclonable functions (PUFs) are basic physical cryptographical primitives, providing to solve tasks such as unclonable identification, digital device authentication and copyright authentication, true random sequence generation, etc. The major features of PUFs are stability, unpredictability and irreproducibility, due to uncontrollable random variations of distinctive features of the raw materials and technological processes used during their manufacturing. Generally, PUF are digital circuits that extract such variations and convert them into a binary format, which applied for further use. Among the variety of PUF types, an Arbiter PUF (APUF) is distinguished, which is a digital circuit with N-bit challenge input and single output for one-bit response generation. The functionality of APUF is based on comparison of transition time of two copies of the test signal along a pair of configurable paths, selected by the challenge value CH from a set of 2N all possible pairs. The result of the comparison is the binary value of the response. The set of all challenge-response pairs is a random, unpredictable and irreproducible in the cases of implementation of cloned PUF circuits both on single and/or on another chips, also using different technologies. This article presents a new approach to the synthesis of the APUF circuits, based on the permutation network elements, which allow to construct the nonlinear structures of pair of paths. This implies the potential complication of building an APUF model to attack its implemented instances. This article presents new schematic solutions for the synthesis of APUF circuits. Also, the main characteristics of the proposed APUF circuits implemented on the Xilinx Zynq-7000 FPGA is analyzed.

Climate changes actualise the need for the transition of Ukraine’s agricultural business to agroforestry systems not only in the steppe but also in the northern regions of the country. The purpose of the study is to examine the features of creating protective stands of Walnut (Juglans regia L.) and Poplars (Populus × euramericana) in Polissya and in the Forest-Steppe of Ukraine. Experimental plantings of Walnut were created by one-year-old seedlings on sod-podzolic sandy loam soils of Zhytomyr Polissya and on carbonate soils of the Western Forest-Steppe, and the analysis of the survival rate of Poplar plantings was conducted on chernozems of the Right-Bank Forest-Steppe. It was established that on sod-podzolic soils, five-year-old plants of Walnut had an average height of 91.8 cm. At the age of 4, some of them bore fruit. The fruit-bearing trees had higher indicators of average height of 13.4% and a diameter of 71.5% compared to the rest. On carbonate soils, the trees showed substantially better growth in height, which is explained by the calciphile nature of the nut. It is determined that an effective way to increase the survival rate of one-year-old seedlings of Poplar varieties Dorskamp, Robusta and I-45/51 is to plant them without trunks. In all the examined varieties, during the first two years, the highest survival rate of seedlings was in the variant without a trunk – from 57.0 to 68.9%, while in seedlings with a trunk – from 50.3% to 68.1%. In 2022, due to irrigation, the survival rate ranged from 74.4% to 88.9%. The average height was mostly also higher in plants that grew from seedlings without a trunk. It was the largest in plants of the Dorskamp clone – 188.6 to 209.3 cm. In uncut plants of this variety, it ranged from 174.0 to 197.2 cm. The practical importance of the study lies in the possibility of developing new forms of Walnut and Poplar and improving technologies for creating forest lands with their involvement, which can be used in Polissya and Forest-Steppe conditions

Purpose. The article aims to improve the methodology and analysis of the financial and economic security of agricultural business in Ukraine for the identification of problematic aspects and the substantiation of policy measures needed to strengthen it. Methodology / approach. The article offers the methodological approach for the comprehensive analysis of the financial and economic security of agricultural business in a region. The conceptual task of the approach is to calculate the empirical indicator of security (composite method) and its structural components (resources, investment, money and credit, debt, finance-economy, and insurance components) based on the identification of the weight of indicators (Principal Components Analysis). Results. The article reveals that the appropriate level of all components of financial and economic security correlates with the financial independence of agricultural entities. In 2018, the index of insurance security (0.798) and money and credit (0.737), debt (0.724), and resources (0.720) components of agricultural business security in Lvivska oblast were above the moderate level. The period of 2018–2022 faced a significant weakening in the resources (by 16.2 p.p.), investment (16.9 p.p.), money and credit (20.6 p.p.), debt (19.0 p.p.), finance-economy (18.0 p.p.), and insurance (5.3 p.p.) components of the sector’s financial and economic security. The average level of financial and economic security in the period under review was 65.0 %, and the average annual rate of decrease was 4.1 p.p. Originality / scientific novelty. The article improves the methodological approach to the complementary assessment of financial and economic security of agricultural business in a region, contributing to the identification of the degree of financial resilience of business entities in the agricultural sector of the regional economy in conditions of war and instability, in order to develop the mechanism for increasing the investment and economic capacity of business. Practical value / implications. The article offers and substantiates an applied approach to assessing the degree of regional financial resilience of agricultural business. Its implementation will allow carrying out a sectoral cut of the state of financial and economic security of the region’s industry and build architectonics of determinants of financial and economic security of business entities.

Purpose: CDKL5 deficiency disorder (CDD) is a developmental and epileptic encephalopathy with multisystemic comorbidities. Cardiovascular involvement in CDD was shown in animal models but is yet poorly described in CDD cohorts. Methods: We identified 38 individuals with genetically confirmed CDD through the Cleveland Clinic CDD specialty clinic and matched 190 individuals with non-genetic epilepsy to them as a comparison group. Natural language processing was applied to yield Human Phenotype Ontology (HPO) terms from medical records. We conducted HPO association testing and manual chart review to explore cardiovascular comorbidities associated with CDD. Results: We extracted 243,541 HPO terms from 30,512 medical encounters. Phenome-wide analysis confirmed well-established CDD phenotypes and identified association of tachycardia with CDD (Odds ratio 4.2, 95% confidence interval (CI) 1.75-9.93, Padj < .001). We found a 99.6-fold enrichment of supraventricular tachycardia (SVT) in CDD encounter notes (Padj < .001), which led to identification of 2 cases of fetal/neonatal onset SVT previously undescribed in CDD. Tachycardia in CDD individuals was associated with the presence of other autonomic symptoms (Odds ratio 5.63, 95% CI 1.08-40.3, P = .038). Conclusion: CDD is associated with tachycardia, potentially including early-onset SVT. Alongside prospective validation studies, semiautomated genotype-phenotype analysis with matched controls is a scalable, rapid, and efficient approach for validating known and identifying novel phenotype associations.

The paper shows the practical possibility of implementing random number generators on field programmable gate arrays (FPGA) by combining various physically unclonable functions. A compact and scalable scheme of a digital random number source based on an asynchronous flip-flop of the D-type is proposed, which combines the characteristics of a static memory physically unclonable functions and a ring oscillator physically unclonable functions. Unlike existing random number generators, the proposed scheme can be used to solve the problem of unclonable identification of digital devices. The article presents experimental results obtained by the proposed generator circuit based on the FPGA Xilinx Zynq. The main modes of operation, probabilistic and statistical characteristics of numerical sequences, generated by the proposed scheme are described.

У статті проаналізовано матеріали археологічних з’їздів, які організовувались у Російській імперії в другій половині ХІХ — на початку ХХ ст., зокрема й каталоги виставок. Встановлено, що експозиції формувалися за територіальним принципом і принципом власності. Пам’ятки надавалися від музеїв, наукових товариств, приватних колекціонерів, дослідників. З’ясовано, що помітною складовою експозицій були старожитності, які стосувалися військової історії. Умовно їх можна поділити на кілька категорій: зброя і обладунки, зокрема археологічні знахідки — вістря стріл, списів, залишки мечів епохи міді та бронзи й ранньої залізної доби, предмети озброєння й амуніції різних історичних епох, предмети фалеристики (жетони та медалі), писемні пам’ятки. Характерною ознакою виставок з’їздів була лише часткова атрибуція експонатів, які стосувалися військової історії, що значно ускладнювало їх систематизацію. Найпотужніші експозиції військових старожитностей було представлено на археологічних з’їздах, які відбувалися в Україні. Акценти ставилися на пам’ятках, пов’язаних з історією козацтва, проте найбільшу частину все-таки становили російські військові меморабілії. Рушійною силою у формуванні виставок майже всіх археологічних з’їздів стали українські дослідники й колекціонери. Ключові слова: археологічний з’їзд, виставка, військові старожитності, озброєння, експозиція, колекція.

The problem of constructing a new class of physically unclonable functions of the arbiter type (APUF) based on the construction of balanced pairs of paths is solved. This makes it possible to significantly increase the stability, uniqueness and uniformity of the APUF. The relevance of the proposed research is associated with the active development of physical cryptography used for the identification of electronic devices and for the generation of cryptographic keys. It is shown that the classical APUF uses a standard basic element that performs three functions, namely, the function of generating a signal delay Generate, the function of choosing a pair of paths Select and the function of switching paths Switch. The execution of all functions by the basic element simultaneously leads to the asymmetry of pairs of paths, which causes a deterioration in the characteristics of the APUF and entails balancing of the paths. As an alternative to the standard basic element, two of its modifications are proposed, in which the Generate function is performed on additional delay lines, and the Switch function on the multiplexer. The use of delay lines with signal delay times much longer than on multiplexers allows constructing the balanced APUF. The proposed approach for building balanced APUF, based on the use of modified basic elements, has demonstrated its efficiency and prospects, including the case of implementing APUF on programmable structures. Practical studies were carried out by a comparative analysis of the classical APUF and balanced APUF implemented on modern FPGAs. The effect of improvement of the characteristics of similar PUFs has been experimentally confirmed, and, first of all, a noticeable improvement in the stability, uniqueness and uniformity of APUFs.

Introduction: This paper focuses on the experiences of thirty-three newcomer Ukrainian Canadians as they adapt to their new multicultural reality in Canada. Challenges of leaving home and adjusting are studied along with changes to identity and strategies of resilience.

Objectives. The problem of constructing a new structure of paths of physically unclonable function of the arbiter type (APUF) on the FPGA is being solved, based on the full use of internal resources of LUT-blocks, which are functionally repeaters. The relevance of the study is associated with the rapid development of physical cryptography tools. Another goal is the developing a methodology for eliminating the asymmetry of the APUF paths associated with the peculiarity of the synthesis of such circuits on the FPGA.Methods. The methods of synthesis of digital devices, their parametric modeling and implementation on rapid prototyping boards are used. A ring oscillator circuit is used to measure the internal propagation delays of signals through the APUF paths.Results. A new structure of the basic element of APUF paths with the use of two functional repeaters is proposed. The necessity of balancing the delays of APUF paths is demonstrated. A technique has been developed to eliminate the asymmetry of signal propagation through APUF paths based on controlled delay lines. The disadvantages of classical approaches as an APUF arbitrator and the need for their modification are shown.Conclusion. The proposed approach to build APUF paths has shown its viability and promise. An improvement in the characteristics of APUF constructed according to the proposed method, as well as a reduction in hardware costs during their implementation compared to classical APUF schemes, is experimentally confirmed. It seems promising to develop the described methodology for constructing the APUF to improve the structure of the arbiter.

Lichens are considered by researchers as bioindicators of environmental pollution by artificial radionuclides, including 137Cs. One of these bioindicator species is epiphytic lichen Hypogymnia physodes (L.) Nyl, the use of which for radioecological monitoring can be modified by several factors: tree species, placement on the tree (branches – trunk), height of sampling, etc. The purpose of this study was to investigate the specific activity of 137Cs in thalli of hypogymnia in pine stands: on trunks of Pinus sylvestris L. and Betula pendula Roth at different heights of sampling in 3 height ranges: 0–65, 65–130, and 130–195 cm, and to analyse the intensity of radionuclide accumulation in the “lichen thallus – tree bark” link for both tree species in all height ranges. The study was conducted in August 2021 in the Korosten district of the Zhytomyr Oblast, Zhytomyr Polissia, on 4 test plots, in the Drevlianskyi nature reserve, mainly in middle-aged pine stands with an admixture of birch, where 130 samples of soil, tree bark, and lichen were taken. Specific activity of 137Cs in the samples was measured using a SEG-001 “AKP-s”-150 gamma-ray spectrometer with a BDEG-20R2 scintillation detector (NaI(Tl). It was demonstrated that the content of 137Сs in the thalli of Hypogymnia physodes at different altitude ranges did not differ statistically significantly at the 95% confidence level in all test plots on pine. A preliminary conclusion was made on the possibility of sampling Hypogymnia physodes thalli on pine trunks in the height range of 0–195 cm; however, for the convenience of sampling, it is recommended to perform sampling within 130–195 cm. It has been proven that both the specific activity of 137Сs in Hypogymnia physodes thalli and the intensity of 137Сs accumulation in the chain “Hypogymnia physodes - tree bark” are approximately 2 times higher on pine compared to birch. It was found that on a birch, the content of 137Сs in lichen between the height ranges of 0–65 and 65–130 cm, and 0–65 and 130–195 cm differs significantly at the 95% confidence level; therefore, it is recommended to sample Hypogymnia physodes on a birch in the range of 65–130 cm

The possibility of using a ring oscillator circuit for measuring the propagation delays of signals through symmetrical APUF paths of various lengths implemented on an FPGA is considered. The creation of the experimental setup and the course of the experiments are described. The dependence of the absolute values of the signal propagation delays and their statistical characteristics on the number of blocks of the symmetric paths under study is investigated. The metrics of stability and intercrystalline uniqueness are calculated based on the obtained experimental data of delay measurements. The improvement of APUF stability and uniqueness depending on the length of the symmetric paths is confirmed.

The methods of constructing physical unclonable functions (PUF), which are the basis of physical cryptography, are analyzed. The broad applicability of the Arbiter PUF, based on the analysis of the delays of the signal transmitted along two paths, is noted. It is shown that the randomness of the delays is explained by technological variations in the manufacturing process of PUF and their dependence on the use of homogeneous repeating elements that ensure the symmetry of the paths. As an alternative to the existing solutions, the article proposes a new approach for constructing an Arbiter PUF based on asymmetric paths. The sources of randomness as logical element delays are investigated. Their diversity and distinctive characteristics are shown depending on the number of inputs to which an active signal is supplied and the values at other inputs. A technique for balancing a set of pairs of paths of Arbiter PUF is proposed, which lays in regulating the duration of the impulse test signal depending on four types of path asymmetry. New structures of Arbiter PUF with asymmetric pairs of paths are proposed. Experimental studies confirm the possibility of using various sources of randomness in the form of signal delays.

Oligotrophic and mesotrophic bogs are common ecosystems in Polissia of Ukraine. After the Chernobyl accident, these ecosystems were contaminated with radionuclides. A common berry plant in these bogs is the cranberry, which is widely used in food industry. The aim of research is to establish dynamics of migration of 137Cs in cranberries during the last 30 years. The obtained results of monitoring studies are necessary for prognosis of radioactive contamination of cranberry. Investigation was conducted on stationary experimental plots (SEP) in Zhytomyr Polissia. 137Cs specific activity was measured on spectrum analyzers with scintillation and semiconductor detectors. Obtained results testify about intensive 137Cs migration on sphagnum bogs of Polissia of Ukraine. Results of investigation conducted after 34 years of Chornobyl accident showed low values of 137Cs specific activity in cranberry (Vaccinium oxycoccus L.) on all stationary experimental plots. This index in 2020 in fresh berries hesitate from 871±82.6 to 286±16.9 Bq/kg (at the permissible level 500 Bq/kg), and in dry shoots – from 1492 (SEP 15) to 6197 Bq/kg (SEP 12). It was found that in the first period (1991-1996) rather significant decreasing of 137Cs specific activity was observed in fresh berries of cranberry – from 3.8 times on SEP 11 to 2.2 times on SEP 12. In the next period (1996-2002) this decreasing was in the limits 1.4-2.9 times that is lower than in previous one. In the following period decreasing of 137Cs specific activity in berries was significantly lower. Revealed regularities of decreasing of 137Cs specific activity in berries during 1991-2020 also confirmed by decreasing of this index in the plant shoots. Total decreasing of this index in dry shoots on the whole period of investigation was: on SEP 11 – from 94590±4236 to 6099±366 Bq/kg (15.5 times), on SEP 12 – from 31800±2325 to 6197±242 Bq/kg (5.1 times), on SEP 15 – from 12120±898 to 1492±112 Bq/kg (8.1 times), on SEP 18 – from 14732±1126 to 1854±112 Bq/kg (7.9 times). Сontinuation of monitoring on stationary experimental plots will allow to predict levels of radioactive contamination of cranberry on the base of mathematical modeling

O b j e c t i v e s. The problem of constructing a new class of physically uncloneable functions (PUF) based on controlling the signal propagation delay through the elements lying on the path of its propagation is being solved. The relevance of this problem is associated with the active development of physical cryptography. For its implementation, the following goals are pursued: the construction of the basic elements of the PUF and their modifications, the development of a methodology for constructing controlled ring oscillators based on XOR elements and controlled ring oscillators based on multi-input signal switching.M e t h o d s. Methods of synthesis and analysis of digital devices were used, including those based on programmable logic integrated circuits (FPGA), the basics of Boolean algebra and circuitry.R e s u l t s. It is shown that combined PUFs based on RS-flip-flops implement the idea of controlling the signal delay by choosing a path, which is a series-connected elements selected in accordance with the PUF request. A technique for constructing an PUF with a controlled delay through each element of the path has been developed as a development of the idea of controlling the signal delay along the path. The features and properties of PUF with controlled delay of signals of the ring oscillator type are investigated and possible solutions are shown for the case of two-bit input requests. A basic element and its modifications are proposed for constructing new PUF structures based on the control of the signal propagation delay. It is shown that the signal delay through the basic element, which is a multi-input XOR element, depends not only on the number of inputs to which the active input signal is applied, but also on fixed values of 0 or 1 at its other inputs. A new PUF structure is presented, namely, a controlled ring oscillator, its implementation is considered for the case of control by setting the inputs and their number, by which the active input signal changes.Co n c l u s i o n. The proposed new approach to the construction of physically uncloneable functions, based on the control of signal delay through logical elements, has shown its efficiency and promise. The effect of the influence on the delays of signal propagation through the logic element, both the number of its inputs, along which the input signals change, leading to a change in the output signal, and their composition, is experimentally confirmed. It seems promising to further developing the ideas of constructing controlled ring oscillators and oscillators with multi-input switching of input signal, as well as the creation of new PUF structures of arbiter type.