Pattern Transitions in Unstable Viscous Convective Medium

Convection in a thin layer of liquid (gas) with temperature dependent viscosity between poorly heat conducting boundaries is studied within framework of the Proctor-Sivashinsky model. This model is examined in order to study both the flow pattern formation and the second-order structural phase transitions as between patterns with translational invariance as well as between structures with broken translational invariance but keeping a long-range order. The spatial spectrum of arising patterns and estimation of their visual defectiveness are analyzed. The relation between the density of pattern defects and spectral characteristics of the pattern is found. We also discuss the noise effects on the formation of pattern defects. The influence of temperature dependence of viscosity on the process of pattern formation and structure transformations is also discussed. It is shown that the temperature dependence of viscosity inhibits structural transition from regular rolls to square cells

ESSENTIAL FEATURES OF MODELS FOR DESCRIPTION OF MODULATION INSTABILITY OF LANGMUIR WAVES IN PLASMA

Various models for description of the modulation instability of intensive Langmuir oscillations in plasma in one–dimensional representation are discussed. It is noted that the kinetic damping on the electrons can violate the conditions of the modulation instability development due to the suppression of the field at the stage of cavities formation, which in this case can reshape. The hydrodynamic model not quite correctly describes the behavior of particles trapped by the spatially inhomogeneous field, neglecting in fact by their inertia that leads to formation of not only very small–scale and deep plasma density cavities, but also triggers to the peaking regime. Considering ions as particles within framework of so–called hybrid models (when electrons are described as fluid and ions as super–particles) allows to see the appearance of groups of fast ions and premature collapse of density cavities due to the intersection of ion trajectories. These models make possible determination of the energy transmitted to ions and low–frequency collective degrees of freedom. Different models are compared with special emphasis on the comparative dynamics of ion heating with development of the instability of intensive Langmuir oscillations in hot (Zakharov’s model) and cold (Silin’s model) plasma

STATE FUNCTION IN UNSTABLE CONVECTIVE MEDIUM

Convection in a thin layer of liquid (gas) with temperature independent viscosity between poorly heat conducting boundaries is studied within framework of the Proctor-Sivashinsky model. We have shown by numerical simulation of the Proctor-Sivashinsky model that the state with certain topology can be described by the state function, which is the sum of squared mode of temperature spatial spectrum on the surface. The transitions between these states are characterized by splashes in time-derivative of this function and different meta-stable structures, corresponding to different values of the state function have different visually distinguishable topologies

Підготовка поліцейського до дій в умовах раптового близького вогневого контакту

Кірічок А. О. Підготовка поліцейського до дій в умовах раптового близького вогневого контакту / А. О. Кірічок, О. С. Скляр, А. В. Забора // Підготовка правоохоронців в системі МВС України в умовах воєнного стану : зб. наук. пр. (м. Харків, 26 трав. 2022 р.) / МВС України, Харків. нац. ун-т внутр. справ, Каф. тактич. та спец. фізич. підготовки ф-ту № 3, Наук. парк «Наука та безпека». – Харків : ХНУВС, 2022. - С. 195-197.В статті розкриваються особливості підготовки поліцейського до дій в умовах раптового близького вогневого контакту. У службовій діяльності поліцейського близький вогневий контакт – це контакт між поліцейським та правопорушником, який застосовує вогнепальну зброю проти нього, на відстані від 2 до 20 метрів. Подібна ситуація характеризується обмеженням у часі на прицілювання, необхідністю відкривати і вести вогонь з не зручних положень та без можливості прицілювання. В такому випадку поліцейському необхідні навички інтуїтивної стрільби. Інтуїтивна стрільба – це вміння швидко та точно спрямовувати зброю, відкривати і вести вогонь у ціль без зорового контакту. Розглядаються альтернативні способи набуття відповідних навичок з використанням імітаційних засобів не летальної дії, а саме пейнтбольного обладнання.The article reveals the features of preparing a policeman for actions in conditions of sudden close fire contact. In police work, close fire contact is contact between a police officer and an offender using firearms against him, at a distance of 2 to 20 meters. Such a situation is characterized by a time limit for aiming, the need to open and fire at uncomfortable positions and without the possibility of aiming. In this case, the policeman needs intuitive shooting skills. Intuitive shooting is the ability to quickly and accurately aim a weapon, open and fire at a target without eye contact. Alternative ways of acquiring appropriate skills using non-lethal imitation tools, namely paintball equipment, are considered.В статье раскрываются особенности подготовки полицейского к действиям в условиях внезапного близкого огневого контакта. В служебной деятельности полицейского близкий огневой контакт – это контакт между полицейским и правонарушителем, применяющим огнестрельное оружие против него, на расстоянии от 2 до 20 метров. Подобная ситуация характеризуется ограничением во времени на прицеливание, необходимостью открывать и вести огонь с неудобных положений и без возможности прицеливания. В таком случае полицейскому необходимы навыки интуитивной стрельбы. Интуитивная стрельба – это умение быстро и точно устремлять оружие, открывать и вести огонь в цель без зрительного контакта. Рассматриваются альтернативные способы обретения соответствующих навыков с использованием имитационных средств не летального действия, а именно пейнтбольного оборудования

The Mitochondrial Ca(2+) Uniporter: Structure, Function, and Pharmacology.

Mitochondrial Ca(2+) uptake is crucial for an array of cellular functions while an imbalance can elicit cell death. In this chapter, we briefly reviewed the various modes of mitochondrial Ca(2+) uptake and our current understanding of mitochondrial Ca(2+) homeostasis in regards to cell physiology and pathophysiology. Further, this chapter focuses on the molecular identities, intracellular regulators as well as the pharmacology of mitochondrial Ca(2+) uniporter complex

Mitochondrial calcium uniporter Mcu controls excitotoxicity and is transcriptionally repressed by neuroprotective nuclear calcium signals

The recent identification of the mitochondrial Ca(2+) uniporter gene (Mcu/Ccdc109a) has enabled us to address its role, and that of mitochondrial Ca(2+) uptake, in neuronal excitotoxicity. Here we show that exogenously expressed Mcu is mitochondrially localized and increases mitochondrial Ca(2+) levels following NMDA receptor activation, leading to increased mitochondrial membrane depolarization and excitotoxic cell death. Knockdown of endogenous Mcu expression reduces NMDA-induced increases in mitochondrial Ca(2+), resulting in lower levels of mitochondrial depolarization and resistance to excitotoxicity. Mcu is subject to dynamic regulation as part of an activity-dependent adaptive mechanism that limits mitochondrial Ca(2+) overload when cytoplasmic Ca(2+) levels are high. Specifically, synaptic activity transcriptionally represses Mcu, via a mechanism involving the nuclear Ca(2+) and CaM kinase-mediated induction of Npas4, resulting in the inhibition of NMDA receptor-induced mitochondrial Ca(2+) uptake and preventing excitotoxic death. This establishes Mcu and the pathways regulating its expression as important determinants of excitotoxicity, which may represent therapeutic targets for excitotoxic disorders

Mitochondrial Ca2+ Overload Underlies Aβ Oligomers Neurotoxicity Providing an Unexpected Mechanism of Neuroprotection by NSAIDs

Dysregulation of intracellular Ca2+ homeostasis may underlie amyloid β peptide (Aβ) toxicity in Alzheimer's Disease (AD) but the mechanism is unknown. In search for this mechanism we found that Aβ1–42 oligomers, the assembly state correlating best with cognitive decline in AD, but not Aβ fibrils, induce a massive entry of Ca2+ in neurons and promote mitochondrial Ca2+ overload as shown by bioluminescence imaging of targeted aequorin in individual neurons. Aβ oligomers induce also mitochondrial permeability transition, cytochrome c release, apoptosis and cell death. Mitochondrial depolarization prevents mitochondrial Ca2+ overload, cytochrome c release and cell death. In addition, we found that a series of non-steroidal anti-inflammatory drugs (NSAIDs) including salicylate, sulindac sulfide, indomethacin, ibuprofen and R-flurbiprofen depolarize mitochondria and inhibit mitochondrial Ca2+ overload, cytochrome c release and cell death induced by Aβ oligomers. Our results indicate that i) mitochondrial Ca2+ overload underlies the neurotoxicity induced by Aβ oligomers and ii) inhibition of mitochondrial Ca2+ overload provides a novel mechanism of neuroprotection by NSAIDs against Aβ oligomers and AD

Flagellar ion channels of sperm: similarities and differences between species

Motility and fertilization potential of mammalian sperm are regulated by ion homeostasis which in turn is under tight control of ion channels and transporters. Sperm intracellular pH, membrane voltage and calcium concentration ([Ca2+]i) are all important for sperm activity within the female reproductive tract. While all mammalian sperm are united in their goal to find and fertilize an egg, the molecular mechanisms they utilize for this purpose are diverse and differ between species especially on the level of ion channels. Recent direct recording from sperm cells of different species indicate the differences between rodent, non-human primate, ruminant, and human sperm on the basic levels of their ion channel regulation. In this review we summarize the current knowledge about ion channel diversity of the animal kingdom and concentrate our attention on flagellar ion channels of mammalian sperm