Compressive strength prediction and composition design of structural lightweight concretes using machine learning methods

ABSTRACT: Introduction. Reducing the density, increasing the strength and other physical-technical characteristics of lightweight concretes are urgent tasks of modern building materials science. To solve them, it is necessary to consider new approaches to the development of compositions of cement systems using effective porous aggregates, binders, chemical and mineral additives, including different nanomodifiers (carbon nanotubes, fullerenes, nanoparticles of SiO2, Al2O3, Fe2O3 , etc.). The complexity of designing modified cement concretes is largely due to their multicomponent nature and a large number of parameters affecting the key characteristics of material. The qualitative solution of such multicriteria problems is possible with the complex implementation of rational physical and computational experiments using mathematical modeling and computer technology. New opportunities for modeling of structure formation processes and predicting properties of multicomponent building materials are emerging with the development of machine learning methods. The purpose of this study is to develop machine learning algorithms that can efficiently establish quantitative dependences for the compressive strength of modified lightweight concretes on their composition, as well as to identify the optimal variation ranges of prescription parameters based on the obtained multifactor models to achieve the required level of controlled mechanical characteristic. Methods and materials. The processing and analysis of experimental research results were carried out using modern methods of machine learning with a teacher used in the problems of regression recovery, knowledge extraction and forecasting. To implement the developed machine learning algorithms, libraries in the Python programming language, in particular NumPy, Pandas, Scikit-learn, Matplotlib, Seaborn, were used. Results and discussion. It is established that the gradient boosting model is the most accurate type among the obtained machine learning models. It is characterized by the following quality metrics: R2 = 0.9557; MAE = 2.4847; MSE = 12.7704; RMSE=3.5736; MAPE = 11.1813%. According to the analysis of this multifactor model, the optimal dosages of pozzolanic and expanding modifiers amounted to 4.5–6.0% and 6.0–7.5% of the binder weight (Portland cement + modifier), respectively, which ensured achievement of the required level of compressive strength (40–70 MPa) of lightweight concretes at the age of 28 days at material density reduced by 3–10% (the range under consideration is 1200–1900 kg/m3). Conclusions. Thus, the study results show the prospects of using machine learning methods for design compositions and predicting properties of multicomponent cement system

Effect of toroidal particle sources on SOL physics in the FT-2 tokamak

Two gas-puffs are used near limiters in the FT-2 tokamak for the purpose of hydrogen refuelling during plasma discharges. This creates toroidal and poloidal asymmetry in particle sources near limiters which has to be considered in modelling. Here, the effect of toroidal asymmetry is simulated using the gyrokinetic code ELMFIRE. Two slightly different toroidal particle sources are used in simulations, and their results are compared with each other, and with experimental measurements to understand the impact of toroidal particle sources on Scrape-off Layer (SOL) physics.Peer reviewe

Comparative analysis of IL-1β blood serum concentration, neutrophil-to-lymphocytes ratio in peripheral blood, and the levels of PD-L1 expression in malignant tissues of the patients with various solid tumors

The action of checkpoint inhibitors is based on activation of T cell antitumor immunity, and, therefore, the search for markers of lymphocyte functional activity before starting the therapy is highly relevant. Determination of the PD-L1 expression in tumor tissues reflects immunosuppressive activity of malignant cells, and it is used as a predictive marker in clinical practice. The ratio of neutrophils to lymphocytes in tumor tissue and in peripheral blood can also indicate the activity of adaptive immunity and correlates with the efficacy of therapy. It has been shown that a high level of interleukin 1 beta in the tumor microenvironment is associated with immunosuppression of lymphocytes and, possibly, reflects the activity of the tumor microenvironment. The aim of this work is to study the relationship between tumor expression of PD-L1, the concentration of serum interleukin-1 beta and the ratio of neutrophils and lymphocytes in peripheral blood.Before starting therapy with checkpoint inhibitors in patients with various solid tumors (n = 50), the serum level of interleukin-1 beta was determined by ELISA (ELISA-Best, Novosibirsk, Russia), expression of PD-L1 in the tumor by immunohistochemical method, complete blood count was performed using cytometry. Statistical analysis was performed in GraphPad Prism 6 (Graph Pad Software, USA) using the statistical methods of Fisher, Mann-Whitney, and Spearman.The average value of the index of the ratio of neutrophils and lymphocytes (NLR) in peripheral blood was 2.65± 0.21 (95% CI 2.22-3.07). The index value of more than 3.5 was found in 18% (9/50) of patients. The mean value of the PD-L1 expression level was 23.02±4.52% (95% CI 13.86-32.18). Expression of PD-L1 in tumor tissue was detected in 60.1% (25/40) of patients, among whom an increased expression of more than 50% was detected in 20.0% (5/25) of cases. A positive weak correlation was found between the concentration of interleukin 1 beta and the number of leukocytes (r = 0.34; p = 0.019) and index (r = 0.32; p = 0.029). The level of PD-L1 expression in tumor tissue also had a weak positive correlation with the serum interleukin 1 beta concentration (r = 0.33; p = 0.037) and the neutrophil-lymphocyte ratio (r = 0.33; p = 0.034). In the group of patients with PD-L1 expression > 5%, the mean value of the concentration of interleukin 1 beta was 1.65±0.62 pg/ml, and the mean value of the index was 4.26±0.94 х 10 9/l, which exceeds the values groups with undetectable PD-L1, but the differences were not statistically significant.The obtained result may indicate the influence of the immunosuppressive properties of the tumor on the state of the patient's immunity. Comprehensive determination of tumor PD-L1 expression, serum interleukin 1 beta concentration and the ratio of neutrophils and lymphocytes in peripheral blood can be used as an assessment of the patient's immune status before starting treatment with checkpoint inhibitors

Key differences between anti-PD-1/PD-L1 inhibitors

Indications  to immunotherapy in cancer treatment continue to expand, thus there are more and more questions about clinical aspects of using different checkpoint inhibitors. Despite similar mechanism of action between widely used antibodies to PD-1 (nivolumab, pembrolizumab, prolgolimab) and PD-L1 (durvalumab, avelumab, atezolizumab), inhibitors are different due to features of monoclonal antibodies structure they are based on. For instance, toxicity leading to discontinuation of treatment occurs more frequently with anti-PD-L1 drugs than PD-1 inhibitors. On the contrary, the average incidence of any grade IRAEs was higher in patients treated with anti-PD-1 drugs. The revealed differences in the toxicity of the analyzed groups of drugs could be associated with the type of action of the drug. The feature of the PD-L1 inhibitors is more frequent occurrence of antibody-dependent cellular cytotoxicity reactions. However, PD-1 inhibitors  showed a statistically significant survival benefit, according to a meta-analysis comparing anti-PD-1 and anti-PD-L1 groups. Besides data on differences in the efficacy and toxicity profiles of these agents, in this article we also analyze different issues in the structure of drug molecules, in particular, the role of LALA mutation in anti-PD-1 inhibitors. Understanding the key distinctive points of check-point inhibitors  (CPI) in the future may allow  to solve the problem of rechallenge  and reintroduction after management of severe IRAEs

Development of a model for the differential diagnosis of community-acquired bacterial pneumonia and viral lung injury in hospitalized adult patients

Relevance. During and after the COVID-19 pandemic, viruses have become a more common cause of pulmonary infections in adults; therefore, the distinction between viral lung injury and community-acquired bacterial pneumonia is of increasing importance. Aim. Development of a model for differentiating community-acquired bacterial pneumonia and viral lung injury, including COVID-19. Materials and methods. This retrospective case–control study included 300 adult patients with viral lung injury and 100 adult patients with community-acquired bacterial pneumonia. Clinical, laboratory, and instrumental data were analyzed, significant factors were selected by which the samples differed, and a model was developed using logistic regression to distinguish between community-acquired bacterial pneumonia and viral lung damage, including COVID-19. Results. The developed model included the following parameters: total protein level, neutrophil/lymphocyte index, heart rate, unilateral infiltration on CT or chest x-ray, vasopressor prescription in the first 24 h of hospitalization, altered level of consciousness, chills, and fatigue. The model had the following characteristics: AUC = 0.94 (0.92–0.96), AUC_PR = 0.84 (0.76 to 0.92), prediction accuracy — 90%, sensitivity — 76%, specificity — 95%, positive predictive value — 83 %. Conclusion. The use of this model can facilitate the differential diagnosis of community-acquired bacterial pneumonia and viral lung injury, including COVID-19, in adults in general wards and intensive care units

Limitations and opportunities of cancer treatment in the COVID-19 pandemic

The COVID-19 pandemic has affected all medical fields and brought up a lot of serious problems. The features of the COVID-19 infection in patients with cancer are important to understand. According to many articles, patients with cancer are more vulnerable to COVID-19 infection. Patients undergoing anticancer treatment have 1-4% morbidity rate. Patients with hematological diseases and lung cancer are at higher risk of SARS-CoV-2 infection and also have more severe symptoms and complications. In this article we discuss the effect of the tumors on the immune system and comprehend the pathogenesis of the coronavirus disease according to its impact on the immunity. Moreover, in the review we analyze available data about the influence of the different types of cancer therapy (chemotherapy, target therapy, radiotherapy and immunotherapy) on the severity of the COVID-19 infection. Evidence on the effect of chemotherapy on severity and mortality from COVID-19 is contradictory. Whereas there are some authors concluding that chemotherapy treatment is not affecting the severity of COVID-19 disease, there are also some works where the connection between these facts was established. At the same time target therapy, radio- and immunotherapy most likely do not worsen the SARS-CoV-2 infection and are not associated with the development of complications. But it’s important to say that the amount of data available for today is insufficient to make a unambiguous conclusion

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Situado no campo dos estudos sobre a influência e recepção, no Brasil e nos Estados Unidos da América, da psicologia produzida na Rússia, este trabalho teve como objetivo apresentar as principais ideias de Gustav Gustavovich Shpet (1879-1937) e refletir sobre o surgimento da Psicologia Étnica como abordagem significativa da psicologia produzida na Rússia, bem como acerca da ausência de sua continuidade. Buscou-se investigar: (a) quais produções intelectuais influenciaram Shpet quando o autor formulou sua proposta de construção da Psicologia Étnica; (b) como Shpet entendia o objetivo e o método da Psicologia Étnica e quais eram os conceitos principais desta área; e (c) se houve diálogo entre as teorias dos psicólogos russos posteriores a Shpet e a proposta formulada por ele. Para isso, tomando como referência os métodos de pesquisa utilizados em estudos de história da psicologia, realizou-se o seguinte procedimento: foram selecionadas obras que influenciaram a produção criativa de Shpet e elaborou-se um resumo destas obras, contendo seus principais conceitos e ideias. Em seguida, fez-se a tradução do russo para o português da obra Introdução à Psicologia Étnica, publicada em 1927 por Shpet, e, a partir dela, desenvolveu-se um resumo contendo os principais conceitos da Psicologia Étnica, seu objetivo e método de investigação. Por fim, foi efetuada uma revisão bibliográfica tanto a respeito das abordagens da Psicologia Soviética que sofreram influência da Psicologia Étnica e das abordagens da Psicologia Social brasileira que sofreram influência da Psicologia Soviética, quanto em relação aos estudos interculturais e sobre raça-etnia realizados inicialmente pela Psicologia Social brasileira. Seguindo essa metodologia, chegou-se a algumas descobertas: as ideias dos pensadores alemães Wilhelm Wundt, Moritz Lazarus e Heymann Steinthal e suas propostas para construir a Völkerpsychologie (Psicologia dos Povos) foram as principais influências intelectuais de Shpet; o objeto da Psicologia Étnica, para Shpet, é a coletividade como atitude psicológica coletiva em relação à cultura; a Psicologia Étnica é proposta como uma ciência descritiva, cujo método envolve a análise e interpretação de signos; as pesquisas interculturais e étnico-raciais foram interrompidas na Rússia por um longo período, devido a questões políticas, e, por isso, a psicologia da União Soviética não incorporou a Psicologia Étnica. Embora a concepção de Shpet não tenha tido continuação, os principais conceitos propostos pelo autor, como coletividade, tipo coletivo, interação e identificação dialogam com conceitos da Psicologia Social contemporânea, como estereótipo, interação social e identidadeThis work is situated in the fields of research on the influence and reception of psychology originated from Russia to the psychology in Brazil and in the United States of America. It is aimed to present the main ideas of Gustav Gustavovich Shpet (1879-1937) and reflects on the emergence of Ethnic Psychology as a significant field of the psychology originated from Russia and about the absence of its continuity. We sought to investigate: (a) what intellectual streams influenced Shpet when the author formulated his proposal for the creation of Ethnic Psychology; (b) how Shpet understood the purpose and method of Ethnic Psychology and what were the key concepts in this area; and (c) whether there was a dialogue between the theories of later Russian psychologists and Shpet\'s proposal. For that, taking as a reference the research methods used in the studies of History of Psychology, we used the following procedure: we selected the works that influenced Shpet\'s theory and we created the summary of these works, emphasizing their main concepts and ideas. Then we made a summary of the work Introduction to Ethnic Psychology, published in 1927 by Shpet, emphasizing the key concepts of Ethnic Psychology, its objective and method of investigation. Then we translated the summary from Russian into Portuguese and, finally, we made the academic papers review on the approaches of Soviet Psychology that were influenced by Ethnic Psychology and on the approaches of Brazilian Social Psychology that were influenced by Soviet Psychology, as well as about the intercultural studies and about race-ethnicity studies initially carried out in Brazilian Social Psychology. The ideas of the German thinkers Wilhelm Wundt, Moritz Lazarus and Heymann Steinthal and their proposals on creation of the Völkerpsychologie (Psychology of the Folk/ Ethnic Psychology) were the main intellectual influencers to Shpet. For Shpet, the object of Ethnic Psychology is the collectivity/groupness as a collective psychological attitude towards culture. Ethnic Psychology should be a descriptive science which method involves the analysis and interpretation of signs. For political reasons, intercultural and ethnic-racial research in Russia was suspended for a long period of time, so the psychology of the Soviet Union did not incorporate Ethnic Psychology. Although Shpet\'s theory has not been continued, the key concepts proposed by the author, such as collectivity, collective type, interaction and identification, enter into dialogue with contemporary Social Psychology concepts such as stereotype, social interaction and identit