Timeline as service of interactive training within discipline “History of computer facilities”

В статье приведен обзор сервисов для создания лент времени. Показаны примеры использования лент времени при изучении дисциплины история вычислительной техники.The review of services for creation of timeline is provided in article. Examples of use of timeline when studying discipline “History of computer facilities” are shown

Inversionless light amplification and optical switching controlled by state-dependent alignment of molecules

We propose a method to achieve amplification without population inversion by anisotropic molecules whose orientation by an external electric field is state-dependent. It is based on decoupling of the lower-state molecules from the resonant light while the excited ones remain emitting. The suitable class of molecules is discussed, the equation for the gain factor is derived, and the magnitude of the inversionless amplification is estimated for the typical experimental conditions. Such switching of the sample from absorbing to amplifying via transparent state is shown to be possible both with the aid of dc and ac control electric fields.Comment: AMS-LaTeX v1.2, 4 pages with 4 figure

МОДЕЛЮВАННЯ ОПТИМАЛЬНОЇ СТРУКТУРИ АКТИВІВ ПІДПРИЄМСТВ М’ЯСОПЕРЕРОБНОЇ ПРОМИСЛОВОСТІ

In today’s economic conditions, problems of functioning of domestic enterprises are not limited by lack of sources of financing of assets, but also often associated with inefficient investment in specific components of property, which adversely affects the level of economic efficiency of Ukrainian enterprises and the development of the economy as a whole. An important factor in making sound, rational and sound decisions about asset management is to improve existing or develop fundamentally new methods and models for optimizing the structure of assets of Ukrainian enterprises using criteria that are most relevant to current economic requirements, environmental challenges and internal objectives. In view of the above, the article demonstrates a clear dependence of the structure of the assets of the enterprise and the key indicators that characterize the effectiveness of its management. The optimal structure of assets for the studied enterprises and possible ways of their achievement are offered taking into account the defined criteria. A comparative assessment of the assets structure of the surveyed enterprises before and after optimization was carried out and on this basis the latter was confirmed by comparing the key parameters of the enterprise performance — profit and market value. A clear sequence of stages of the asset structure optimization model is proposed and described, along with methodological aspects of determining the effective structure of assets, the feasibility of its practical application at Ukrainian enterprises is proved through the achievement of the key goal of the enterprise activity — maximization of market value and profit.У сучасних умовах господарювання проблеми функціонування вітчизняних підприємств не обмежуються браком джерел фінансування активів, але часто пов’язані з неефективним вкладенням коштів у конкретні складові майна, що негативно позначається на рівні ефективності господарювання підприємств України та розвитку економіки в цілому. Вагомим чинником ухвалення зважених, раціональних та обґрунтованих рішень щодо управління активами є удосконалення наявних або розроблення принципово нових методів і моделей оптимізації структури активів підприємств України з використанням критеріїв, які найбільше відповідають сучасним економічним вимогам, викликам зовнішнього середовища та внутрішнім цільовим орієнтирам діяльності підприємства. Зважаючи на вищезазначене, продемонстровано чітку залежність структури активів підприємства і ключових показників, що характеризують ефективність його господарювання. Запропоновано оптимальну з урахуванням визначених критеріїв структуру активів для досліджуваних підприємств та можливі способи їх досягнення. Проведено порівняльну оцінку структури активів досліджуваних підприємств до і після оптимізації та на цій основі підтверджено ефективність останньої шляхом порівняння ключових параметрів ефективності діяльності підприємства — прибутку та ринкової вартості. Запропоновано та описано послідовність етапів моделі оптимізації структури активів із зазначенням методичних аспектів визначення оптимальної структури активів, доведено доцільність її практичного застосування на підприємствах України через досягнення ключової цілі діяльності підприємства — збільшення ринкової вартості та прибутку

Inversionless gain in a three-level system driven by a strong field and collisions

Inversionless gain in a three-level system driven by a strong external field and by collisions with a buffer gas is investigated. The mechanism of populating of the upper laser level contributed by the collision transfer as well as by relaxation caused by a buffer gas is discussed in detail. Explicit formulae for analysis of optimal conditions are derived. The mechanism developed here for the incoherent pump could be generalized to other systems.Comment: RevTeX, 9 pages, 4 eps figure

Combination of hypomorphic mutations of the Drosophila homologues of aryl hydrocarbon receptor and nucleosome assembly protein family genes disrupts morphogenesis, memory and detoxification

Aryl hydrocarbon receptor is essential for biological responses to endogenous and exogenous toxins in mammals. Its Drosophila homolog spineless plays an important role in fly morphogenesis. We have previously shown that during morphogenesis spineless genetically interacts with CG5017 gene, which encodes a nucleosome assembly factor and may affect cognitive function of the fly. We now demonstrate synergistic interactions of spineless and CG5017 in pathways controlling oxidative stress response and long-term memory formation in Drosophila melanogaster. Oxidative stress was induced by low doses of X-ray irradiation of flies carrying hypomorphic mutation of spineless, mutation of CG5017, and their combination. To determine the sensitivity of these mutants to pharmacological modifiers of the irradiation effect, we irradiated flies growing on standard medium supplemented by radiosensitizer furazidin and radioprotector serotonin. The effects of irradiation were investigated by analyzing leg and antenna morphological structures and by using real-time PCR to measure mRNA expression levels for spineless, Cyp6g1 and Gst-theta genes. We also examined long-term memory in these mutants using conditioned courtship suppression paradigm. Our results show that the interaction of spineless and CG5017 is important for regulation of morphogenesis, long-term memory formation, and detoxification during oxidative stress. Since spineless and CG5017 are evolutionary conserved, these results must be considered when evaluating the risk of combining similar mutations in other organisms, including humans

The physical and mechanical characteristics of cast steel 20ГЛ after electric spark alloing and ultrasonic impact treatment

Досліджено мікротвердість, структуру, фазовий склад і корозійну стійкість низьколегованої ливарної сталі 20ГЛ у вихідному стані після стандартної термообробки, а також після електроіскрового легування(ЕІЛ) різними елементами (Ni, Cr, Mo) і ультразвукової ударної обробки (УЗУО). Великий розмір феритної і перлітної складових обумовлює суттєву різницю між значеннями мікротвердості сталі як у вихідному, так і деформованому станах. Застосування ЕІЛ призводить до суттєвішого зміцнення, ніж УЗУО, особливо у випадку легування хромом та молібденом. Це зумовлено складними фазовими та структурними перетвореннями, які протікають при комбінованій обробці ЕІЛ+УЗУО: формування ОЦК твердих розчинів Fe-Cr і Fe-Mo, зміцнених інтерметалідними та карбідними фазами. Шорсткість поверхонь зразків при цьому значно знижувалась. Усі сформовані поверхневі шари на сталі 20ГЛ, леговані нікелем, хромом та молібденом, характеризуються більшим потенціалом корозії та меншим струмом корозії в порівнянні зі стальними зразками у вихідному стані, що свідчить про їх вищу стійкість до електрохімічної корозії. Згідно з аналізом морфології кородованих поверхонь найефективнішим виявилось ЕІЛ поверхневого шару нікелем, яке призводить до формування в ньому ГЦК твердого розчину залізо-нікель.Microhardness, structure, phase composition and corrosion resistance of low alloyed cast 20GL steel are studied in initial state after standard heat treatment, and after the electro-sparking alloying (ESA) by different elements (Ni, Cr, Mo) and ultrasonic impact treatment (UIT). Relatively large size of ferritic and pearlitic constituents determines a substantial difference between the microhardness values of the steel both in initial and in deformed states. The UIT process leads to slight increase in microhardness, and for the specimen after the UIT processing for 60 s the microhardness becomes 4 GPa, which is 1.45 times higher than that for initial state. Application of the ESA+UIT results in more substantial hardening than UIT, especially in the case of alloying with chromium (5.81 GPa) and molybdenum (7.47 GPa), which are 2.0 – 3.5 times and 2.7 – 4.3 times higher than initial specimen, respectively. It is due to complex phase and structural transformations, which occur at the combined ESA+UIT treatment. The ESA processes with chromium and molybdenum leads to formation of BCC Fe-Cr and Fe-Mo solid solutions strengthened by intermetallic phases and/or chromium-iron carbides. Using the nickel electrode at the ESA process promotes formation the FCC Fe-Ni solid solution. In all the cases, the UIT process decreases the surface roughness of specimens considerably. All the formed superficial layers on the 20GL steel, alloyed with nickel, chromium and molybdenum are characterized by higher corrosion potential and lower corrosion current in comparison with the initial steel specimens that testifies to their higher resistances to electrochemical corrosion. According to the analysis of morphology of corroded surfaces the ESA process of superficial layer with nickel electrode is the most effective one, which leads to formation the iron-nickel FCC solid solution. The superficial layers alloyed with chromium and molybdenum underwent more severe corrosion attack due to their heterogenic phase structure. Considerable misfit between lattices of BCC solid solutions (Fe-Cr or Fe-Mo) and intermetallic or carbide phases with crystalline lattices of low symmetry results in formation of defects and stresses can also promote higher corrosion rate

Changes in the pattern of sleep disturbances in healthy subjects under 21-day antiorthostatic hypokinesia

Background. Antiorthostatic hypokinesia (ANOH) reproduces some of the effects of weightlessness on the human body and is used to study adaptation to space flight conditions. It is known that ANOH affects nighttime sleep, but there is no information in the literature on the sequence of occurrence of sleep disorders in ANOH.The aim of the research was to study the dynamics of subjective changes in assessing sleep quality under conditions of antiorthostatic hypokinesia.Materials and methods. Six healthy male volunteers (age from 26 to 34  years) participated in the experiment with 21-day ANOH. They were on a medical bed with a body inclination angle relative to the horizon of –6° for 21 days. To assess sleep quality, a structured questionnaire was used that assessed sleep duration, rate of falling asleep, night awakenings, the presence of daytime sleepiness, and daytime falling asleep.Results. Based on the assessment of the dynamics of the sleep efficiency index (SEI), three stages of adaptation were identified. At the stage of acute adaptation (the first 3 days), there is a decrease in SEI from 96.4 to 91.3 (p < 0.01), a statistically significant prolongation of falling asleep from 17.6 to 33.6  minutes (p  <  0.01), an increase duration of night awakenings up to 17.4 minutes, increase in daytime sleepiness by 11 %. In the next 3 days (the “recovery” stage), there is a statistically significant increase in SEI compared to the 1st stage to 94.7 (p < 0.01), but it remains statistically significantly lower than the background values (p < 0.004). The number of complaints about daytime sleepiness increases (up to 42  %), evening bedtime shifts later by 26 minutes. At the 3rd stage (the remaining nights) there is a relative stabilization of the sleep-wake cycle.Conclusion. Under conditions of 21-day ANOH, a gradual change in the pattern of sleep disturbances occurs. The most negative changes in terms of subjective assessment were noted in the first three days. Then there is an improvement in falling asleep, a decrease in night awakenings, combined with an increase in daytime sleepiness and the formation of a schedule with a later bedtime

Surface plasmon-polaritons in graphene, embedded into medium with gain and losses

The paper deals with the theoretical consideration of surface plasmon-polaritons in the graphene monolayer, embedded into dielectric with spatially separated gain and losses. It is demonstrated, that presence of gain and losses in the system leads to the formation of additional mode of graphene surface plasmon-polaritons, which does not have its counterpart in the conservative system. When the gain and losses are mutually balanced, the position of exceptional point-transition point between unbroken and broken [Formula: see text]-symmetry-can be effectively tuned by graphene's doping. In the case of unbalanced gain and losses the spectrum of surface plasmon-polaritons contains spectral singularity, whose frequency is also adjustable through the electrostatic gating of graphene.European Commission through the project 'Graphene—Driven Revolutions in ICT and Beyond' (Ref. No. 785219), and the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Financing UID/FIS/04650/2019. Additionally, YVB acknowledges financing from FEDER and the portuguese Foundation for Science and Technology (FCT) through project PTDC/FIS-MAC/28887/201

Cannibalism as a life boat mechanism

Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one