Thermal collapse of a granular gas under gravity

Free cooling of a gas of inelastically colliding hard spheres represents a central paradigm of kinetic theory of granular gases. At zero gravity the temperature of a freely cooling homogeneous granular gas follows a power law in time. How does gravity, which brings inhomogeneity, affect the cooling? We combine molecular dynamics simulations, a numerical solution of hydrodynamic equations and an analytic theory to show that a granular gas cooling under gravity undergoes thermal collapse: it cools down to zero temperature and condenses on the bottom of the container in a finite time.Comment: 4 pages, 12 eps figures, to appear in PR

Exercise of Civil-Law Rights: Categories in the Context of Their Digitalization

With digital rights designated to the objects of civil rights in Art. 128 of the Civil Code, Art. 141.1 amended to include their legal definition, and a new wording of Art. 309 introducing ‘smart contracts’, the digital reform recently enacted in the Russian civil law has seen some major novelties. Needless to say, these accomplishments have challenged Russian civil law theorists. Discussions are underway to resolve both doctrinal and applied issues that had been more than obvious well before the legislative move which, according to one of the opinions, was an ‘admissible’ experiment. What remains now is to assess its viability. The author of this work set the goal to explore the way digital rights, primarily those that arise from ‘smart-contracts’, are (or can be) ‘exercised’. This is a perspective where a fundamental gap between ‘smart-contract’ and civil contract emerges. In the author’s view, efforts to overcome it by expanding the concept of subjective rights and the principles of contract law will not succeed. Since no proper verification of the interests of the parties to ‘smart contracts’, which are essentially a computer code, is available, and as the same refers to linguistic verification of their will, there is no way for ‘smart contracts’ to enter the domain of law. Digital ‘contracts’ are unapt to honour the principle of contractual equilibrium. The ‘self-execution’ of these contracts, as well as their inherent inability to be violated, are, if put in the civilistic context, their fatal flaw, and by no means a virtue. The article also shows that though instruments to ensure a relative irreversibility of rights are not unfamiliar to private law, they cannot serve as an excuse for such regime in contract obligations. That fixation of rights and transactions in digital form has become fully enshrined in the civil law is arguably the only compatible with its principles as well as much anticipated impact the digital reform has brought about

Integrity and Singularity: on a Civil Law Protection of the Privacy in the Countries of the Eurasian Economic Union

The article assesses the need for a privacy right to be enshrined in the Russian civil law. In effect, the issue is whether time is ripe for the protection of a universal right that would cover all personal interests. Aim. To propose and substantiate civil law protection of the privacy by means of a single subjective right. Tasks. To submit the rationale for enshrining a universal personal right, to offer a concept of the privacy as a protectable legal asset, to respond to possible objections, to demonstrate advantages of a unified legal regime.Methods. Alongside general scientific approaches, the methods used in the research include interpretation technique, comparative jurisprudence, applying assessment of law efficiency based on its concept as a way to harmonize private interests.Results. While the idea of personal space is making its way to a greater identity in the minds of the Russian people, the civil legislation provides protection to such interests only in cases provided for by the law. However, the judicial protection of all personal interests by default outside the legal regime would be an inefficient solution. The author offers his own theory of privacy as a legal category. Apart of providing defense for any relevant interests, legal recognition of a single personal right will allow to identify features of protectability, to stipulate the exemptions, and make easier for the courts to deny protection in cases of abuse of the right.Conclusions. The development of civil legislation is increasingly lagging behind the need in protection of personal interests. The author stands up for a single personal right to be enshrined in the law. The crucial test is whether such a right live up to expectations of the parties of relations in question, i.e. citizens of Russia, rather than the extent to which such a rule is recognized by other jurisdictions

Patterns and Collective Behavior in Granular Media: Theoretical Concepts

Granular materials are ubiquitous in our daily lives. While they have been a subject of intensive engineering research for centuries, in the last decade granular matter attracted significant attention of physicists. Yet despite a major efforts by many groups, the theoretical description of granular systems remains largely a plethora of different, often contradicting concepts and approaches. Authors give an overview of various theoretical models emerged in the physics of granular matter, with the focus on the onset of collective behavior and pattern formation. Their aim is two-fold: to identify general principles common for granular systems and other complex non-equilibrium systems, and to elucidate important distinctions between collective behavior in granular and continuum pattern-forming systems.Comment: Submitted to Reviews of Modern Physics. Full text with figures (2Mb pdf) avaliable at http://mti.msd.anl.gov/AransonTsimringReview/aranson_tsimring.pdf Community responce is appreciated. Comments/suggestions send to [email protected]

Дослідження життєвого циклу комп’ютерних вірусів

This article is devoted to the research of the dynamics of the spread of computer viruses in the network. The model, which is considered in the article, is based on the SIR model, which was proposed by Kermack W. and O. McKendrick A.G. In accordance with this model, individuals are divided into three groups: susceptible, infected, and cured. Individuals move from the first group to the second, and from the second to the third. The total number of individuals remains constant over time. The changes in individuals in groups are described by a system of three differential equations. In the equations, there are coefficients that are associated with the rate of infection and the rate of treatment. The total rate of change in the number of individuals in the three groups is zero. In this article, a modification of the SIR model was made. In each equation was introduced deviating argument. The deviating argument mathematically expresses the impact of the aftereffect of the processes of infection and treatment. The impact of deviating argument on the dynamics of the spread of computer viruses in the network is considered in the work. Systems of three and of two equations are considered for different values of the deviating argument. The initial problems for these systems with the help of analytical methods are reduced to Cauchy problems, which are solved by numerical methods using a fourth-order Runge-Kutta algorithm. The results are presented in the form of graphs that express the dependence of the number of computers on time. The article analyzes the results obtained and makes conclusions. These studies are new and relevant now and can be used in subsequent studies of computer viruses. The model can be modified and improved. The article may be of interest to specialists who are engaged in research in the field of computer technology, as well as mathematicians who are engaged in the construction and research of mathematical models.В работе исследуется динамика жизненного цикла компьютерных вирусов, которая описывается системами с последействием.В работе исследуется динамика жизненного цикла компьютерных вирусов, которая описывается системами с последействиемВ роботі досліджується динаміка життєвого циклу комп’ютерних вірусів, яка описується системами з післядією

Дослідження динаміки розповсюдження комп’ютерного вірусу в мережі

The dynamics of the life cycle of a computer virus is investigated in this work. Virus life cycle is described with delayed differential equations systems.Исследована динамика жизненного цикла компьютерного вируса, которая описывается системами с последействием.Досліджено динаміку життєвого циклу комп’ютерного вірусу, яка описується системами з післядією

Cell-Cycle Dependence of Transcription Dominates Noise in Gene Expression

The large variability in mRNA and protein levels found from both static and dynamic measurements in single cells has been largely attributed to random periods of transcription, often occurring in bursts. The cell cycle has a pronounced global role in affecting transcriptional and translational output, but how this influences transcriptional statistics from noisy promoters is unknown and generally ignored by current stochastic models. Here we show that variable transcription from the synthetic tetO promoter in S. cerevisiae is dominated by its dependence on the cell cycle. Real-time measurements of fluorescent protein at high expression levels indicate tetO promoters increase transcription rate ~2-fold in S/G2/M similar to constitutive genes. At low expression levels, where tetO promoters are thought to generate infrequent bursts of transcription, we observe random pulses of expression restricted to S/G2/M, which are correlated between homologous promoters present in the same cell. The analysis of static, single-cell mRNA measurements at different points along the cell cycle corroborates these findings. Our results demonstrate that highly variable mRNA distributions in yeast are not solely the result of randomly switching between periods of active and inactive gene expression, but instead largely driven by differences in transcriptional activity between G1 and S/G2/M.GM095733BBBE 103316MIT Startup Fun

Nuclear Power in Taiwan: A Clash of Views

Рукопись поступила в редакцию: 26.03.21. Принята к публикации: 23.07.21.Received: 26.03.21. Accepted: 23.07.21.В статье рассматривается проблема атомной энергетики Тайваня, ставшая особенно актуальной после выборов 2016 г., когда победившая Демократическая прогрессивная партия (ДПП), во главе с президентом Цай Инвэнь, объявила об отказе от использования атомной энергетики к 2025 г. Данный курс, принятый на фоне многотысячных протестов после аварии на Фукусиме-1, к 2020 году обрел немало как сторонников, так и противников, став предметом политической борьбы между ныне правящей ДПП и оппозиционным Гоминьданом. В работе анализируется аргументация сторон, описываются противоборствующие организационные структуры и их связь с политическими силами. Можно выделить 3 основных общих вопроса, по которым идут споры: безопасность, экология и экономика. В сфере безопасности противники атомной энергетики на Тайване используют в качестве примера аварию на Чернобыльской АЭС и Фукусиме-1, говоря об опасности атомной энергетики как таковой, невозможности ее контролировать и обеспечить надлежащий уровень безопасности ядерных объектов. Сторонники же доказывают, что системы безопасности АЭС на Тайване превосходят аналогичные на Фукусиме-1, а сама компания постоянно их модернизирует. В сфере экологии наиболее остро стоит вопрос утилизации низкоактивных ядерных отходов, уделяется большое внимание уменьшению выбросов CO2 в атмосферу. В сфере экономики отмечается недостаток резервных мощностей на Тайване, подчеркивается относительная дороговизна альтернативных экологически чистых источников энергии. Антиядерные активисты говорят о высокой стоимости строительства и эксплуатации АЭС, утверждая, что в долгосрочной перспективе АЭС проигрывает возобновляемым источникам энергии как экономически, так и технологически, и считая атомную энергетику устаревающей отраслью.The article addresses the issue of nuclear energy in Taiwan, which became particularly relevant after the 2016 elections, when the winning Democratic Progressive Party (DPP), led by President Tsai Ing-wen, announced the rejection of the use of nuclear energy by 2025. By 2020, adopted against the backdrop of thousands of protests after the Fukushima-1 accident, this course gained many supporters and opponents and became the subject of a political struggle between the currently ruling DPP and its rival Kuomintang. The paper analyzes the reasoning by the parties, describes the opposing organizational structures and their relations with political forces. Three main general issues are in the focus of debates: security, ecology and economics. In security matters, opponents of nuclear energy in Taiwan use the Chernobyl accident and Fukushima-1 as an example, talking about the danger of nuclear energy per se, the inability to control it and ensure an appropriate level of safety of nuclear facilities. Supporters argue that the safety systems of nuclear power plants in Taiwan are superior to those at Fukushima-1, and the company itself is constantly upgrading them. In the ecology sector, the most acute issue is low-level nuclear waste disposal, and the opponents pay much attention to reducing CO2 emissions into the atmosphere. In the area of economic matters, there is a lack of reserve capacity in Taiwan, and the parties emphasize the relatively high cost of alternative environmentally friendly energy sources. Anti-nuclear activists talk about the high costs of building and operating nuclear power plants, arguing that in the long run, nuclear power plants lose out to renewable energy sources both economically and technologically, considering atomic power as an outdated industry

Selected heterozygosity at cis-regulatory sequences increases the expression homogeneity of a cell population in humans

Background: Examples of heterozygote advantage in humans are scarce and limited to protein-coding sequences. Here, we attempt a genome-wide functional inference of advantageous heterozygosity at cis-regulatory regions. Results: The single-nucleotide polymorphisms bearing the signatures of balancing selection are enriched in active cis-regulatory regions of immune cells and epithelial cells, the latter of which provide barrier function and innate immunity. Examples associated with ancient trans-specific balancing selection are also discovered. Allelic imbalance in chromatin accessibility and divergence in transcription factor motif sequences indicate that these balanced polymorphisms cause distinct regulatory variation. However, a majority of these variants show no association with the expression level of the target gene. Instead, single-cell experimental data for gene expression and chromatin accessibility demonstrate that heterozygous sequences can lower cell-to-cell variability in proportion to selection strengths. This negative correlation is more pronounced for highly expressed genes and consistently observed when using different data and methods. Based on mathematical modeling, we hypothesize that extrinsic noise from fluctuations in transcription factor activity may be amplified in homozygotes, whereas it is buffered in heterozygotes. While high expression levels are coupled with intrinsic noise reduction, regulatory heterozygosity can contribute to the suppression of extrinsic noise. Conclusions: This mechanism may confer a selective advantage by increasing cell population homogeneity and thereby enhancing the collective action of the cells, especially of those involved in the defense systems in humansope

Role of Cell-to-Cell Variability in Activating a Positive Feedback Antiviral Response in Human Dendritic Cells

In the first few hours following Newcastle disease viral infection of human monocyte-derived dendritic cells, the induction of IFNB1 is extremely low and the secreted type I interferon response is below the limits of ELISA assay. However, many interferon-induced genes are activated at this time, for example DDX58 (RIGI), which in response to viral RNA induces IFNB1. We investigated whether the early induction of IFNBI in only a small percentage of infected cells leads to low level IFN secretion that then induces IFN-responsive genes in all cells. We developed an agent-based mathematical model to explore the IFNBI and DDX58 temporal dynamics. Simulations showed that a small number of early responder cells provide a mechanism for efficient and controlled activation of the DDX58-IFNBI positive feedback loop. The model predicted distributions of single cell responses that were confirmed by single cell mRNA measurements. The results suggest that large cell-to-cell variation plays an important role in the early innate immune response, and that the variability is essential for the efficient activation of the IFNB1 based feedback loop