Spectral Green's-function method in driven open quantum dynamics

A method based on spectral Green's functions is presented for the simulation of driven open quantum dynamics that can be described by the Lindblad master equation in Liouville density operator space. The method extends the Hilbert space formalism and provides simple algebraic connections between the driven and nondriven dynamics in the spectral frequency domain. The formalism shows remarkable analogies to the use of Green's functions in quantum field theory, such as the elementary excitation energies and the Dyson self-energy equation. To demonstrate its potential, we apply the method to a coherently driven dissipative ensemble of two-level systems comprising a single “active” subsystem interacting with N “passive” subsystems—a generic model with important applications in quantum optics and dynamic nuclear polarization. The method dramatically reduces the computational cost compared with simulations based on solving the full master equation, thus making it possible to study and optimize many-body correlated states up to the physically realistic limit of an arbitrarily large N

Non-Indigenous Cladocera (Crustacea: Branchiopoda): From a Few Notorious Cases to a Potential Global Faunal Mixing in Aquatic Ecosystems

Non-indigenous species may pose a threat to native ecosystems worldwide. In aquatic environments, invasives may have a negative impact on human food security and livelihoods. Several water fleas (Crustacea: Branchiopoda: Cladocera) are notorious invasive alien species influencing large freshwater lake systems and even inland seas. In the current review, we discuss the state of knowledge regarding non-indigenous species in the Cladocera and their invasiveness potential in different continents. We argue that the potential impacts and occurrence of cladoceran exotics may be higher than generally assumed. We critically review 79 cases from literature sources, involving 61 cladoceran taxa where records outside of their natural distribution ranges were previously interpreted as invasions. We assessed the probability of natural range expansions versus human-mediated introductions and we discuss several major corridors of invasion. We estimate human-mediated transportations for at least 43 taxa (out of 61; ca 70%), while other cases can be seen as natural expansions of their distribution ranges (not necessarily/not likely human-mediated) and/or taxonomical confusion. We confirm non-indigenous presence in recipient regions for at least 41 cladoceran taxa, of which several are true invasives (i.e., with negative impacts on native ecosystems). The majority are zooplankters with effects on pelagic freshwater ecosystems, yet we also report on introductions by littoral taxa. We argue that cryptic introductions of cladocerans are taking place on a global scale, yet they remain under the radar. We highlight several striking case studies, such as the Ponto-Caspian onychopods that have invaded the Baltic Sea and the Laurentian Great Lakes, and several clones of the anomopod genera Daphnia and Bosmina that have successfully colonised new environments, causing equilibria shifts in native aquatic worlds. At the same time, we dispel some myths about taxa that were misconstrued as invasive in certain localities. Based on our review, the first of its kind for freshwater zooplankton, future environmental monitoring tools including molecular techniques and detailed surveys with rigorous and critical taxonomical assessments may help to provide a clearer picture on the extent of invasiveness of cladocerans.O

Dynamic nuclear polarization as kinetically constrained diffusion

Dynamic nuclear polarization (DNP) is a promising strategy for generating a significantly increased nonthermal spin polarization in nuclear magnetic resonance (NMR) and its applications that range from medicine diagnostics to material science. Being a genuine nonequilibrium effect, DNP circumvents the need for strong magnetic fields. However, despite intense research, a detailed theoretical understanding of the precise mechanism behind DNP is currently lacking. We address this issue by focusing on a simple instance of DNP—so-called solid effect DNP—which is formulated in terms of a quantum central spin model where a single electron is coupled to an ensemble of interacting nuclei. We show analytically that the nonequilibrium buildup of polarization heavily relies on a mechanism which can be interpreted as kinetically constrained diffusion. Beyond revealing this insight, our approach furthermore permits numerical studies of ensembles containing thousands of spins that are typically intractable when formulated in terms of a quantum master equation. We believe that this represents an important step forward in the quest of harnessing nonequilibrium many-body quantum physics for technological applications

Plasticity and dystonia: a hypothesis shrouded in variability.

Studying plasticity mechanisms with Professor John Rothwell was a shared highlight of our careers. In this article, we discuss non-invasive brain stimulation techniques which aim to induce and quantify plasticity, the mechanisms and nature of their inherent variability and use such observations to review the idea that excessive and abnormal plasticity is a pathophysiological substrate of dystonia. We have tried to define the tone of our review by a couple of Professor John Rothwell's many inspiring characteristics; his endless curiosity to refine knowledge and disease models by scientific exploration and his wise yet humble readiness to revise scientific doctrines when the evidence is supportive. We conclude that high variability of response to non-invasive brain stimulation plasticity protocols significantly clouds the interpretation of historical findings in dystonia research. There is an opportunity to wipe the slate clean of assumptions and armed with an informative literature in health, re-evaluate whether excessive plasticity has a causal role in the pathophysiology of dystonia

Spin dynamic simulations of solid effect DNP: the role of the relaxation superoperator

Relaxation plays a crucial role in the spin dynamics of dynamic nuclear polarisation. We review here two different strategies that have recently been used to incorporate relaxation in models to predict the spin dynamics of solid effect dynamic nuclear polarisation. A detailed explanation is provided how the Lindblad-Kossakowski form of the master equation can be used to describe relaxation in a spin system. Fluctuations of the spin interactions with the environment as a cause of relaxation are discussed and it is demonstrated how the relaxation superoperator acting in Liouville space on the density operator can be derived in the Lindblad-Kossakowski form by averaging out non-secular terms in an appropriate interaction frame. Furthermore we provide a formalism for the derivation of the relaxation superoperator starting with a choice of a basis set in Hilbert space. We show that the differences in the prediction of the nuclear polarisation dynamics that are found for certain parameter choices arise from the use of different interaction frames in the two different strategies. In addition we provide a summary of different relaxation mechanism that need to be considered to obtain more realistic spin dynamic simulations of solid effect dynamic nuclear polarisation

Influence of Employments an Athletics Gymnastics on Physical Preparedness of Students of Senior Classes

У статті проаналізовано методичні підходи до побудови занять атлетичною гімнастикою з учнями старших класів, визначено вплив засобів атлетичної гімнастики на фізичну підготовленість школярів. In the articles the exposed methodical going near the construction of employments an athletics gymnastics with the students of senior classes, influence of facilities of athletics gymnastics is certain on physical preparedness of students

Electroencephalograms features of the early stage Parkinson’s disease

© 2014, Pleiades Publishing, Ltd. A new method for analyzing the time-frequency dynamics of brain’s background electrical activity is described. It is used to detect at least three main features of Parkinson’s disease (PD) in its early stages: (1) hemispheric asymmetry in the time-frequency characteristics (EEG) in the central recording areas of the motor cortex, (2) the emergence in these recording areas of EEG rhythms in the frequency range of 4–6 Hz and its relation to electromyograms (EMG) and the mechanical tremor of contralateral limbs in the case of tremor-dominant PD, and (3) the disruption of the dominant rhythm corresponding to views generally held on the disorganization of different systems in PD

ВЕТЕРИНАРНЫЕ ПРОБЛЕМЫ ОЛЕНЕВОДСТВА В РЕГИОНЕ ЕВРОПЕЙСКОГО СЕВЕРА РОССИИ

Objective of research. As deer are kept year-round on pasture (in summer in tundra in the northern coast of the Russian arctic; in winter – in forest-tundra and northern taiga), biogeocenosis and natural focality of most parasitic and infectious diseases were formed over the years. That should be considered when developing methods for combating them, and to determine the optimal timing of mass treatment and prevention measures.Materials and methods. The question naturally arises, which living and nonliving components ensure pathogen survivability, contribute to the emergence and spread of infectious and invasive diseases. Each disease is characterized by specific factors requiring careful examination and generalization based on the study of clinical records and epizootic diseases in reindeer of the European North of Russia.Results and discussion. Dominant diseases of reindeer in the European region ofNorthern Russia, requiring greater attention of veterinary experts and against which it is necessary to conduct a regular complex of veterinary, prevention and treatment measures are: anthrax, edemagenosis, cephenomiosis, necrobacillosis, echinococcosis, cysticercosis, rabies, leptospirosis, number of helminthoses (strongylatosis, monieziasis, echinococcosis, cysticercosis, etc.). This is a brucellosis-free region, and for many tens years no outbreaks of FMD were reported.  The vast majority of the tundra is located in the permafrost zone; the area is dotted with numerous canals, lakes, rivers, streams, marshes, between which in summer on shallow layered soil, grow bushes of willow, dwarf birch, berries, grass and lichen, the main food of deer. The fauna of the tundra is rich and diverse. Here live wolves, foxes, bears, rodents (lemmings, mice), rabbits, birds (geese, ducks, partridges, gulls) and other animals. In summer, "clouds" of midges (mosquitoes, midges, horseflies, flies) are flying in the air. In the region, there are still places virtually untouched by man.  However, in recent years, intensive industrial development of the region began to carry out exploration and extraction of oil, gas and other minerals. Oil and gas pipelines, roads, power lines are built which certainly cannot affect negatively the extremely vulnerable nature of the North. For example, reindeer moss trampled or torn down by moving offroaders can be restored only after 7-10 years. Summer season in the North is a very short period, there are usually few warm and sunny days. These negative factors lead to reduced pastures and do not contribute to the growth of the deer population, their health status and fatness.Цель исследования. Поскольку олени содержатся на круглогодовом выпасе (летом в тундре прибрежных районов Северных морей, зимой в лесотундре и северо-таёжной зоне), существует сложившийся годами биогеоценоз и природная очаговость большинства паразитарных и инфекционных заболеваний, что необходимо учитывать при разработке методов борьбы с ними, и определить оптимальные сроки проведения массовых лечебно-профилактических мероприятий. Материалы и методы. Естественно возникает вопрос, какие живые и неживые компоненты природы обеспечивают сохранность возбудителя болезни, способствуют возникновению и распространению инфекционных и инвазионных заболеваний. Для каждой болезни факторы индивидуальны, требуют внимательного изучения и обобщения на основе изучения истории болезней и эпизоотий в оленеводстве Европейского Севера России, что и представлено в настоящей работе. Результаты и обсуждение. Доминирующими болезнями оленей в регионе Европейского Севера России, требующими повышенного внимания ветеринарных специалистов и против которых необходимо регулярно проводить комплекс ветеринарно-профилактических и лечебных мероприятий являются: сибирская язва, эдемагеноз, цефеномиоз, некробактериоз, эхинококкоз, цистицеркоз, бешенство и дикование, лептоспироз, ряд гельминтозов (стронгилятозы, мониезиоз, эхинококкоз, цистицеркоз и др.). Регион благополучен по бруцеллёзу и уже десятки лет не отмечалось вспышек ящура.  Подавляющая часть тундры находится в зоне вечной мерзлоты; местность испещрена многочисленными протоками, озёрами, реками, ручьями, болотами, между которыми, на оттаивающем в летний период неглубоком слое почвы, растут кустарники ивняка, карликовых берёз, ягодника, трава и ягель, основной корм оленей. Животный мир тундры богат и разнообразен. Здесь уживаются волки, песцы, медведи, многочисленные грызуны (лемминги, мыши), зайцы, птицы (гуси, утки, куропатки, чайки) и пр. живность. В летний период в воздухе летает буквально «тучами» гнус (комары, мошки, слепни, мухи). В регионе имеются ещё места, практически, не тронутые человеком, однако, в последние годы началось интенсивное промышленное освоение края в целях поиска и добычи нефти, газа, других полезных ископаемых.  Прокладываются и строятся нефте- и газопроводы, дороги, ЛЭП и пр., что, безусловно не может не отразиться негативно на чрезвычайно ранимой природе Севера. Например, вытоптанный или порушенный при движении вездеходов ягель может восстановиться лишь через 7-10 лет. Летний период на Севере кратковременный и, как правило, с малым числом тёплых, солнечных дней. Все эти негативные факторы ведут к сокращению площадей пастбищ и не способствуют росту поголовья оленей, состоянию их здоровья и упитанности

Nanostructured front electrodes for perovskite/c-Si tandem photovoltaics

The rise in the power conversion efficiency (PCE) of perovskite solar cells has triggered enormous interest in perovskite-based tandem photovoltaics. One key challenge is to achieve high transmission of low energy photons into the bottom cell. Here, nanostructured front electrodes for 4-terminal perovskite/crystalline-silicon (perovskite/c-Si) tandem solar cells are developed by conformal deposition of indium tin oxide (ITO) on self-assembled polystyrene nanopillars. The nanostructured ITO is optimized for reduced reflection and increased transmission with a tradeoff in increased sheet resistance. In the optimum case, the nanostructured ITO electrodes enhance the transmittance by ∼7% (relative) compared to planar references. Perovskite/c-Si tandem devices with nanostructured ITO exhibit enhanced short-circuit current density (2.9 mA/cm2 absolute) and PCE (1.7% absolute) in the bottom c-Si solar cell compared to the reference. The improved light in-coupling is more pronounced for elevated angle of incidence. Energy yield enhancement up to ∼10% (relative) is achieved for perovskite/c-Si tandem architecture with the nanostructured ITO electrodes. It is also shown that these nanostructured ITO electrodes are also compatible with various other perovskite-based tandem architectures and bear the potential to improve the PCE up to 27.0%

УСТАНОВЛЕНИЕ ЗАВИСИМОСТИ ИЗМЕНЕНИЙ НОРМАЛЬНЫХ НАПРЯЖЕНИЙ ОТ СТЕПЕНИ ИЗНОСА РЕЛЬСА

The safety of railway operation is associated with the stress state in rails, depending on the applied load (both vertical and lateral load) and on changes in the rail profile associated with wear.The objective of this work is to obtain and describe the dependence of the edge stresses in a rail as a function of wear magnitude. The obtained dependence is used to determine the maximum stresses. The technique consists in constructing a spline approximation of a worn rail profile. The proposed approach allows simulating real rail wear (vertical and lateral wearing). The work has applied in MathCAD environment a practical algorithm for calculating the influence of the degree of rail wear on the increase in the maximum bending stresses and on decrease in permissible loads.A technique has been developed for simulating the profile and calculating the normal contour stresses during rail bending, considering the wear magnitude. It is applied to the movement of a rail wheelset along the rail track in a straight section of the track. The technique also allows considering horizontal lateral force from the wheel flange during movement of various types of rolling stock in curved track sections. Calculations have been carried out and a nonlinear dependence of the growth of maximum compressive and tensile normal stresses on the degree of wear has been obtained. Three characteristic ranges have been identified and recommendations have been given for reducing the destructive load with regard to rail wear.Безопасность эксплуатации железнодорожных путей связана с напряжённым состоянием в рельсах, зависящим от  прикладываемой нагрузки (вертикальной и боковой) и изменений профиля, связанных с износом.Целью настоящей работы является получение зависимости кромочных напряжений в рельсе как функции от величины износа. Полученная зависимость используется для определения максимальных напряжений. Методика заключается в построении сплайн-аппроксимации профиля изношенного рельса. Предложенный подход позволяет моделировать реальный износ рельса (вертикальный и боковой).В работе применён практический алгоритм расчёта в среде MathCAD влияния степени износа рельса на увеличение максимальных напряжений изгиба и снижение допускаемых нагрузок.Разработана методика моделирования профиля ирасчёта контурных нормальных напряжений при изгибе рельса с учётом степени износа. Рассматривается движение колёсной пары в рельсовой колее на прямом участке пути. В то же время методика допускает также учёт горизонтального бокового усилия от гребня колеса при движении различных видов подвижного состава в кривых участках пути.Проведены расчёты и получена нелинейная зависимость роста максимальных сжимающих и растягивающих  нормальных напряжений от степени износа. Выделены три характерных диапазона и даны рекомендации по снижению разрушающей нагрузки с учётом износа рельса