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Background: Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2) infection can cause feared consequences, such as affecting microcirculatory activity. The combined use of HRV analysis, genetic algorithms, and machine learning classifiers can be helpful in better understanding the characteristics of microcirculation that are mainly affected by COVID-19 infection. Methods: This study aimed to verify the presence of microcirculation alterations in patients with COVID-19 infection, performing Heart Rate Variability (HRV) parameters analysis extracted from PhotoPlethysmoGraphy (PPG) signals. The dataset included 97 subjects divided into two groups: healthy (50 subjects) and patients affected by mild-severity COVID-19 (47 subjects). A total of 26 parameters were extracted by the HRV analysis and were investigated using genetic algorithms with three different subject selection methods and five different machine learning classifiers. Results: Three parameters: meanRR, alpha1, and sd2/sd1 were considered significant, combining the results obtained by the genetic algorithm. Finally, machine learning classifications were performed by training classifiers with only those three features. The best result was achieved by the binary Decision Tree classifier, achieving accuracy of 82%, specificity (or precision) of 86%, and sensitivity of 79%. Conclusions: The study’s results highlight the ability to use HRV parameters extraction from PPG signals, combined with genetic algorithms and machine learning classifiers, to determine which features are most helpful in discriminating between healthy and mild-severity COVID-19-affected subjects.

Augmented and mixed reality in the medical field is becoming increasingly important. The creation and visualization of digital models similar to reality could be a great help to increase the user experience during augmented or mixed reality activities like surgical planning and educational, training and testing phases of medical students. This study introduces a technique for enhancing a 3D digital model reconstructed from cone-beam computed tomography images with its real coloured texture using an Intel D435 RGBD camera. This method is based on iteratively projecting the two models onto a 2D plane, identifying their contours and then minimizing the distance between them. Finally, the coloured digital models were displayed in mixed reality through a Microsoft HoloLens 2 and an application to interact with them using hand gestures was developed. The registration error between the two 3D models evaluated using 30,000 random points indicates values of: 1.1 ± 1.3 mm on the x-axis, 0.7 ± 0.8 mm on the y-axis, and 0.9 ± 1.2 mm on the z-axis. This result was achieved in three iterations, starting from an average registration error on the three axes of 1.4 mm to reach 0.9 mm. The heatmap created to visualize the spatial distribution of the error shows how it is uniformly distributed over the surface of the pointcloud obtained with the RGBD camera, except for some areas of the nose and ears where the registration error tends to increase. The obtained results indicate that the proposed methodology seems effective. In addition, since the used RGBD camera is inexpensive, future approaches based on the simultaneous use of multiple cameras could further improve the results. Finally, the augmented reality visualization of the obtained result is innovative and could provide support in all those cases where the visualization of three-dimensional medical models is necessary.

To quantify the discolouration of the temporary acetal resins in vivo, based on the weeks of follow-up and the salivary pH in the three thirds of the tooth. To find out if the final CIELAB coordinates can be predicted from the initial colour coordinates, the salivary pH, the situation (in thirds) and the weeks of follow-up. Colour coordinates (L, C, and h) were recorded by spectrophotometry in 13 participants fitted with hybrid provisional complete dentures made of acetal resin. Colour recordings were made on the day of placement and after several weeks of follow-up (6 to 31 weeks). Salivary pH was also measured as a predictor variable for colour change. The ANOVA statistical test and regression models have been used. The highest colour difference according to ∆Eab* was 27.46 units after 15 weeks of follow-up and the lowest was 7.34 units after 17 weeks of follow-up. Neither in the cervical nor in the middle third any regressor variable (initial L*, initial C*, initial h*, salivary pH and weeks of follow-up) was able to significantly predict any of the final colour coordinates (p > 0.05). The colour change of the temporary acetal resins used exceeds the threshold of clinical acceptability, and it is not acceptable to maintain satisfactory aesthetics. The weeks of follow-up and the salivary pH are not capable of satisfactorily predicting the final color coordinates of the acetal resins.

The frequency of waterlogging episodes has increased due to unpredictable and intense rainfalls. However, less is known about waterlogging memory and its interaction with other climate change events, such as elevated CO2 concentration (e[CO2]). This study investigated the combined effects of e[CO2] and two rounds of waterlogging stress on the growth of cultivated tomato (Solanum lycopersicum) and wild tomato (S. pimpinellifolium). The aim is to elucidate the interaction between genotypes and environmental factors and thereby to improve crop resilience to climate change. We found that two rounds of treatments appeared to induce different acclimation strategies of the two tomato genotypes. S. pimpinellifolium responded more negatively to the first-time waterlogging than S. lycopersicum, as indicated by decreased photosynthesis and biomass loss. Nevertheless, the two genotypes respond similarly when waterlogging stress recurred, showing that they could maintain a higher leaf photosynthesis compared to single stress, especially for the wild genotype. This showed that waterlogging priming played a positive role in stress memory in both tomato genotypes. Multivariate analysis showed that waterlogging played a dominant role when combined with [CO2] for both the cultivated and wild tomato genotypes. This work will benefit agricultural production strategies by pinpointing the positive effects of e[CO2] and waterlogging memory.

The atmospheric CO2 concentration (a[CO2]) is increasing at an unprecedented pace. Exogenous melatonin plays positive roles in the response of plants to abiotic stresses, including drought and cold. The effect of elevated CO2 concentration (e[CO2]) accompanied by exogenous melatonin on plants under drought and cold stresses remains unknown. Here, tomato plants were grown under a[CO2] and e[CO2], with half of the plants pre-treated with melatonin. The plants were subsequently treated with drought stress followed by cold stress. The results showed that a decreased net photosynthetic rate (PN) was aggravated by a prolonged water deficit. The PN was partially restored after recovery from drought but stayed low under a successive cold stress. Starch content was downregulated by drought but upregulated by cold. The e[CO2] enhanced PN of the plants under non-stressed conditions, and moderate drought and recovery but not severe drought. Stomatal conductance (gs) and the transpiration rate (E) was less inhibited by drought under e[CO2] than under a[CO2]. Tomato grown under e[CO2] had better leaf cooling than under a[CO2] when subjected to drought. Moreover, melatonin enhanced PN during recovery from drought and cold stress, and enhanced biomass accumulation in tomato under e[CO2]. The chlorophyll a content in plants treated with melatonin was higher than in non-treated plants under e[CO2] during cold stress. Our findings will improve the knowledge on plant responses to abiotic stresses in a future [CO2]-rich environment accompanied by exogenous melatonin.

During the last decade (2000–2010), we have witnessed an unprecedented rise in food prices, especially from the world and European market viewpoint. The article aims to analyze the development of prices in the food market in the Czech Republic and to identify the influence of global and European prices development on domestic food price development and price development of selected food products. The article focuses primarily on the sensitivity of Czech food price development and especially on sensitivity of the selected commodity aggregations price development on the global and European market price growth. Furthermore, it is analyzed the impact of changes in value added tax rate from 10% to 14% on food prices in general and then on the prices of selected food products in retails network. The results of the analysis are following. The Czech food market reacts sensitively to changes in food prices on the global market as well as on the EU market but the EU price development is determining for the CR. In terms of price response to change in the VAT rate, it appears that the growth rate is not absorbed on the production side but it is largely transferred to consumer prices. The selected food sample also showed high responsiveness in the development of prices to changes in the EU market prices but there are certain variations given by specifics of the Czech market.

This paper discusses the development of consumer prices in the Czech Republic within the context of food prices in the European Union and the global market. The article is identifying the development of the foodstuff consumer prices in the market in the Czech Republic in relation to World and European consumer prices. Subsequently, the development of food consumer prices in the Czech market is analyzed in relation to selected commodities and products marketed in the Czech retail chains. Lastly, the status of individual retail chains in the Czech market is defined and the consumer prices and price differences existing amongst the selected major chains operating on the Czech market are analyzed. In relation to the objectives of this article it is then possible to state the following: prices on the Czech market correlate very strongly, especially in relation to the EU countries markets, but are very weak in relation to the world market. The sensitivity of the Czech consumer prices is very high – it is very flexible towards changes within the framework of the prices levels on the market of the EU but, by contrast, it is completely inflexible in respect to the changes in the prices levels on the world market. The Czech Republic follows the general development price trends existing in the EU countries markets.The growth in food prices on the Czech market is very close to the average growth rate of the food prices index in the EU market. Regarding the prices development on the Czech Republic market, it can be noted that, in relation to particular segments of the commodity food prices, the most dynamic growth was recorded in the case of fruit and vegetables, oils and fats, dairy products, fish and seafood, poultry, beef and cereals and bakery products.It is also important to mention that in the Czech Republic there are no uniform price levels between individual regions. In respect to the nature of the Czech retail market, a comment should be made that on the one hand it is very concentrated – a relatively small number of players control the character of the market – nevertheless, but in comparison with the European average, it can be said that the market is highly competitive, since none of the market subjects clearly dominates. Individual retail chains in their pricing policies more or less follow the general price trends and tendencies, reflecting the development of the domestic market and in, particular, the EU market.

The global meat market and primarily the chicken meat market represents a very dynamically developing area. The objective of the present article is the analysis of the chicken meat market in the world in order to identify the basic development trends associated with the development of production of and trade in chicken meat, and also in order to identify the individual entities controlling the global chicken meat market. In methodological terms, the article analyzes the development of production of, consumption of and trade (export and import) in chicken meat in the years 1961–2009. The main sources of data necessary for the processing of the individual analyses are the FAOSTAT and UN COMTRADE databases. The results of the conducted analysis show the following findings. World production of poultry meat increased from 7.5 million tons to more than 86 million tons. The global market reacted in a flexible manner, in which there was an increase in volumes of executed trade from 271 thousand tons/year in the year 1961 to more than 10.7 million tons/year in the year 2010. Further, the value of world trade in chicken meat within the analyzed period increased from approximately USD 169 million to approximately USD 16 billion. If we analyze the global chicken meat market, it may be stated that it is very concentrated. The analysis of the global market further shows that Brazil, the USA and China represent, in terms of global production, consumption and trade, the main driving force on the chicken meat market. These three countries have a share in global production of approximately 46%, their share in global consumption ranges at a level of over 40%. The share of these countries in global export ranges at a level exceeding 50%.

The Czech retail market has changed its structure and form during the last twenty years. The influence of two factors is especially significant. The first one is the growth of internationalization and the second one is market concentration growth. The significant opening process of the Czech economy, accompanied by the liberalization of the Czech market process, enabled the international retail companies to penetrate the national retail market. The most powerful European retail companies are now present in the Czech market. The available shopping area/cap is also one of the largest in Europe. Retail chains have taken a dominant position in the market, and because of their market power they are able to determine trade/contract conditions for domestic suppliers. Retail chains’ sales have been constantly growing. While in 2006 the value of sales was about 258.5 billion CZK, in 2008 it was about 312.2 billion CZK. The impact of the economic crisis on the Czech retail market has not been as stressful as it was abroad. In 2009, a slowdown of the Czech retail market was recorded, but the value of sales decreased by only 3 billion CZK (in comparison with 2008). The highest sales (59 billion CZK) were recorded by the Lidl & Schwarz-Gruppe, which is the owner of two dominant retail chains in the Czech retail market (Kaufland and Lidl). The main aim of the paper is to evaluate the selected aspects, which have been influencing the relationship between multinational companies (retail companies – supermarkets and hypermarkets) and local (Czech) suppliers of agrarian and foodstuff products (farmers and foodstuff companies). The paper analyses the problem of abuse of multinational companies’ significant market power in relation to their suppliers. Based on a pilot project, the efficiency of market force law, and its use in practice, are analysed. The main idea is to analyse the following problems: the impact of 30 days payment period for goods delivered, under cost prices required by retail companies, and the structure of fees and charges required by retail companies.