THE INFLUENCE OF PRECIPITATION PARAMETERS OF VACUUM- ARC NANOCRYSTALLINE COATING TI-MO-N ON NANOHARDNESS AND WEAR RESISTANCE OF PISTON RINGS

It has been investigated the influence of multi-layered vacuum-arc nanostructure coating Ti - Mo - N on wear resistance of piston rings. The influence of vacuum-arc coating parameters on nanohardness has been set

Inference of functional neural connectivity and convergence acceleration methods

The knowledge of the maps of neuronal interactions is key for system neuroscience, but at the moment we possess relatively little of it . The recent development of experimental methods which allow a simultaneous recording of the spiking activity, but not the intracellular voltage, of thousands of neurons gives us an opportunity to start filling that gap. In Chapter 2, I present a method for the inference of the parameters of the leaky integrate-and-fire (LIF) model featuring time-dependent currents and conductances based only on the extracellular recording of spiking in the network. The fitted parameters can describe the functional connections in the network, as well as the internal properties of the cells. The method can also be used to determine whether a single-compartment model of a neuron should include conductance- or current-based synapses, or their mixture. In addition, because the same mathematical model describes some of the flavors of the Drift Diffusion Model (DDM), popular in the studies of decision making process, the presented method can be readily used to fit their parameters. Making the proposed inference procedure -- based on the expectation-maximization (EM) algorithm -- accurate and robust, necessitated a development of a new numerical adaptive-grid (AG) method for the forward-backward (FB) propagation of the probability density, which is required in the computation of the sufficient statistic in the EM algorithm. These topics are covered in Chapter 3. Another issue which had to be addressed in order to obtain a usable inference algorithm is the well known slow convergence of the EM algorithm in the flat regions of the loglikelihood. Two complementary approaches to this issue are presented in this dissertation. In Chapter 4, I present a new framework for the acceleration of convergence of iterative algorithms (not limited to the EM) which unifies all previously known methods and allows us to construct a new method demonstrating the best performance of them all. To make the computations even faster, I wrote a Matlab package which allows them to be done in parallel on several machines and clusters. As one can see, all the aforementioned projects were sprouted up from one "head" project on the inference of the LIF model parameters. At the end of the dissertation, I briefly describe a disconnected project which is devoted to the development of a flexible experimental setup (software and hardware) for behavioral experiments, with a specific application to a particular type of the virtual Morris water maze experiment (VMWM)

Neural Integrator: A Sandpile Model

We investigated a model for the neural integrator based on hysteretic units connected by positive feedback. Hysteresis is assumed to emerge from the intrinsic properties of the cells. We consider the recurrent networks containing either bistable or multistable neurons. We apply our analysis to the oculomotor velocity-to-position neural integrator that calculates eye positions using the inputs that carry information about eye angular velocity. By analyzing this system in the parameter space, we show the following. The direction of hysteresis in the neuronal response may be reversed for the system with recurrent connections compared to the case of unconnected neurons. Thus, for the NMDA receptor-based bistability, the firing rates after ON saccades may be higher than after OFF saccades for the same eye position. The reversal of hysteresis occurs in this model only when the size of hysteresis differs from neuron to neuron. We also relate the macroscopic leak time constant of the integrator to the rate of microscopic spontaneous noise-driven transitions in the hysteretic units. Finally, we investigate the conditions under which the hysteretic integrator may have no threshold for integration

Закономерности роста тканей у свиней

Through the research of the swine's tissue growth, it was discovered that tissue growth in postnatal life is unequal. During the first two months of piggery's life muscular tissue has the highest rate of growth; the next ones are adipose tissue and osseous tissue. During the following age periods adipose tissue ranks first by the growth speed, then muscular and osseous tissues.При изучении роста тканей у свиней было установлено, что в постнатальный период он происходит неравномерно. В первые 2 месяца жизни поросят наивысшей скоростью роста обладает мышечная ткань, за ней следуют жировая и костная. В последующие возрастные периоды первое место по скорости роста занимает жировая ткань, за ней мышечная и костная

Ischemia effect on ATPase activity of heart mitochondria in young and old rats

ATPase activity alterations in rats of different age groups during the total myocardial ischemia were studied. It was determined that only mitochondrial oligomycin-sensitive ATPase was sensitive to effect of the total myocardial ischemia. The fact that addition of magnesium ions in the incubation medium eliminated ischemic effect in 3-months old rats and weakened it in 24-months old rats pointed to important role of magnesium ions in structure-functional reconstruction of mitochondria under myocardial ischemia. Young 3-months old rats were established to be more tolerant to myocardial ischemic damage than old animals. Вивчено зміни АТФазної активності у щурів різного віку при тотальній ішемії міокарда. Встановлено, що тільки мітохондріальна олігоміцин-чутлива АТФаза виявила чутливість до тотальної ішемії міокарда. Додавання іонів магнію до середовища інкубації знімає вплив ішемії у 3-місячних щурів та послаблює його у 24-місячних щурів, що свідчить про важливу роль іонів магнію в структурно-функціональній перебудові мітохондрій при ішемії міокарда. Встановлено, що молоді, 3-місячні, щури більш стійкі до ішемічного пошкодження міокарда, ніж старі тварини. Изучены изменения АТФазной активности у крыс разного возраста при тотальной ишемии миокарда. Установлено, что только митохондриальная олигомицин- чувствительная АТФаза проявляла чувствительность к тотальной ишемии миокарда. Добавление ионов магния в среду инкубации снимает влияние ишемии у 3-месячных крыс и ослабляет его у 24-месячных крыс, что свидетельствует о важной роли ионов магния в структурно-функциональной перестройке митохондрий при ишемии миокарда. Установлено, что молодые, 3-месячные, крысы более устойчивы к ишемическому повреждению миокарда, чем старые животные

Рост мышц у баранов эдильбаевской породы при умеренном их выращивании и откорме

A study of muscle growth was carried out on newborn sheep of the edilbaevskoy breed aged 3, 7, 10, 12,5- months old under moderate rearing and fattening. It was established that muscles grow most intensively up till 7 months age in lambs. Muscle increase takes place unevenly according to anatomical regions. The absolute weight of trunk muscles in 12,5 months old compared to newborn lambs increases by 10.68 times, muscles of fore limbs by 7,63 times, muscles of hind limbs by 9.21 times, that brings to a change in their ratio. For instance, the relative weight of muscles of the abdominal walls increases from 5.45% (in newborn) to 8,91%; muscles of the shoulder girdle increase from 13.41% to 14,43%; muscles of fore limbs decrease from 17,56% to 13,91%; muscles of hind limbs decrease from 35,22% to 34,17% respectively. The distribution of muscular mass into different parts of the limbs depends on the genetic program of morphogenesis and character of distribution of functional loading; thus, the more proximal the group of muscles, the higher is the rate of growth and multiplication of weight increase.В статье рассказывается об изучении роста мышц у новорожденных, 3-, 7-, 10- и 12,5-месячных баранов эдильбаевской породы при умеренном их выращивании и откорме. Установлено, что наиболее интенсивно мышцы растут до 7-месячного возраста. Прирост мышц по анатомическим областям происходит неравномерно. Абсолютная масса мышц туловища у 12,5-месячных баранов увеличивается по сравнению с новорожденными в 1,68 раза, грудной конечности - в 7,63 раза и тазовой конечности - в 9,21 раза, что приводит к изменению их соотношения. Так, относительная масса мышц брюшной стенки повышается с 5,45% (новорожденные) до 8,91%; плечевого пояса - с 13,41% до 14,43%; грудной конечности - уменьшается с 17,56% до 13,91%; тазовой конечности - уменьшается с 35,22% до 34,17% соответственно. Распределение мышечной массы по звеньям конечностей обусловлено генетической программой морфогенеза и характером распределения функциональной нагрузки; чем проксимальнее группа мышц конечностей, тем выше скорость их роста и кратность увеличения массы

Spin-orbit torque control of spin waves in a ferromagnetic waveguide

Spin-orbit torque (SOT) created by a spin current injected into a ferromagnet by an adjacent heavy metal represents an efficient tool for the excitation and manipulation of spin waves. Here we report the micromagnetic simulations describing the influence of SOT on the propagation of spin waves in the $\mathrm{W}/\mathrm{CoFeB}/\mathrm{MgO}$ nanostructure having voltage-controlled magnetic anisotropy (VCMA). The simulations show that two spin waves travelling in the opposite directions can be generated in the center of the $\mathrm{CoFeB}$ waveguide via the modulation of VCMA induced by a microwave voltage locally applied to the $\mathrm{MgO}$ nanolayer. The amplitudes of these waves exponentially decrease with the propagation distance with similar decay lengths of about 2.5 $\mu$m. In the presence of a direct electric current injected into the $\mathrm{W}$ film beneath the waveguide center, the decay lengths of two spin waves change in the opposite way owing to different directions of the electric currents flowing in the underlying halves of the $\mathrm{W}$ layer. Remarkably, above the critical current density $J_\mathrm{W} \approx 2 \times 10^{10}$ A m$^{-2}$, SOT provides the amplification of the spin wave propagating in one half of the waveguide and strongly accelerates the attenuation of the wave travelling in the other half. As a result, a long-distance spin-wave propagation takes place in a half of the $\mathrm{CoFeB}$ waveguide only. Furthermore, by reversing the polarity of the dc voltage applied to the heavy-metal layer one can change the propagation area and switch the travel direction of the spin wave in the ferromagnetic waveguide. Thus, the $\mathrm{W}/\mathrm{CoFeB}/\mathrm{MgO}$ nanostructure can be employed as an electrically controlled magnonic device converting the electrical input signal into a spin signal, which can be transmitted to one of two outputs of the device.Comment: 7 pages, 6 figure