Stability analysis of some integrable Euler equations for SO(n)

A family of special cases of the integrable Euler equations on $so(n)$ introduced by Manakov in 1976 is considered. The equilibrium points are found and their stability is studied. Heteroclinic orbits are constructed that connect unstable equilibria and are given by the orbits of certain 1-parameter subgroups of SO(n). The results are complete in the case $n=4$ and incomplete for $n>4$.Comment: 15 pages, LaTeX, minor stylistic changes in v

Polaron in t-J model

We present numeric results for ground state and angle resolved photoemission spectra (ARPES) for single hole in t-J model coupled to optical phonons. The systematic-error free diagrammatic Monte Carlo is employed where the Feynman graphs for the Matsubara Green function in imaginary time are summed up completely with respect to phonons variables, while magnetic variables are subjected to non-crossing approximation. We obtain that at electron-phonon coupling constants relevant for high Tc cuprates the polaron undergoes self-trapping crossover to strong coupling limit and theoretical ARPES demonstrate features observed in experiment: a broad peak in the bottom of the spectra has momentum dependence which coincides with that of hole in pure t-J model.Comment: 4 pages, 4 figure

Distribution of localized states from fine analysis of electron spin resonance spectra of organic semiconductors: Physical meaning and methodology

We develop an analytical method for the processing of electron spin resonance (ESR) spectra. The goal is to obtain the distributions of trapped carriers over both their degree of localization and their binding energy in semiconductor crystals or films composed of regularly aligned organic molecules [Phys. Rev. Lett. v. 104, 056602 (2010)]. Our method has two steps. We first carry out a fine analysis of the shape of the ESR spectra due to the trapped carriers; this reveals the distribution of the trap density of the states over the degree of localization. This analysis is based on the reasonable assumption that the linewidth of the trapped carriers is predetermined by their degree of localization because of the hyperfine mechanism. We then transform the distribution over the degree of localization into a distribution over the binding energies. The transformation uses the relationships between the binding energies and the localization parameters of the trapped carriers. The particular relation for the system under study is obtained by the Holstein model for trapped polarons using a diagrammatic Monte Carlo analysis. We illustrate the application of the method to pentacene organic thin-film transistors.Comment: 14 pages, 11 figure

Polarized Electric Current in Semiclassical Transport with Spin-Orbit Interaction

Semiclassical solutions of two-dimensional Schrodinger equation with spin-orbit interaction and smooth potential are considered. In the leading order, spin polarization is in-plane and follows the evolution of the electron momentum for a given subband. Out-of-plane spin polarization appears as a quantum correction, for which an explicit expression is obtained. We demonstrate how spin-polarized currents can be achieved with the help of a barrier or quantum point contact open for transmission only in the lower subband.Comment: 6 pages, 2 figure

Економічний аналіз фармацевтичного підприємства щодо перспективи інноваційного розвитку на прикладі ПАТ «Фармак»

У статті розглянуто проблему розвитку та конкурентоспроможності підприємств фармацевтичної галузі України як однієї з провідних наукоємних та прибуткових галузей діяльності у світі. Наголошено на важливості розвитку фармацевтичного ринку як одного з елементів забезпечення національної безпеки держави. Проблему інноваційного та технологічного розвитку галузей української економіки визначено як центральну в сучасних економічних умовах. Зазначено, що задля забезпечення стабільного розвитку фармацевтичної індустрії необхідним є використання передових концепцій, методів та інструментів менеджменту. Досліджено перспективи урізноманітнення продуктового портфелю інноваційними розробками за рахунок залучення зовнішніх інвестицій. Проаналізовано можливість переходу фармацевтичної галузі на міжнародні стандарти розробки, досліджень, виробництва та сертифікації продукції, так як можливість інноваційного розвитку є основним фактором конкурентоспроможності таких високотехнологічних галузей промисловості як фармацевтика. Досліджено фінансово-економічне становище фармацевтичної галузі України у розрізі основних фінансових показників. Незважаючи на системний макроекономічний спад промислового виробництва по країні, були приведені дані, що підтверджують стійкий тренд до зростання обсягів продажу фармацевтичної продукції вітчизняних підприємств. Інтерпретовано результати аналізу та визначення можливості забезпечення інноваційного розвитку на прикладі ПАТ «Фармак» як одного з підприємств-лідерів фармацевтичної промисловості, використовуючи економічні дані підприємства, елементи фінансово-економічного аналізу та визначення ступеня фінансової стійкості за допомогою апарату нечіткої логіки. В статті була підтверджена думка щодо важливості проведення інвестицій у технологічні інновації. Визначено напрями потенційних майбутніх досліджень.The article considers the problem of development and competitiveness of the pharmaceutical industry companies of Ukraine as one of the leading knowledge-intensive and profitable industries in the world. The importance of development of the pharmaceutical market as one of the elements of ensuring the national security of the state is emphasized. The problem of innovation and technological development of Ukrainian economy sectors is defined as central in modern economic conditions. It is noted that it is necessary to use advanced concepts, methods and management tools in order to ensure the stable development of the pharmaceutical industry. The prospects of diversification of the product portfolio with innovative developments by attracting foreign investments are investigated. The possibility of the pharmaceutical industry turn to the international standards of development, research, production and product certification is analyzed, since the possibility of innovation development is the main factor of competitiveness of such high-tech industries as pharmaceutical. The financial and economic situation of Ukraine pharmaceutical industry in the context of the main financial indicators is investigated. Despite the systemic macroeconomic downturn in industrial production across the country, data was provided confirming a steady trend towards increasing sales of domestic pharmaceuticals enterprises. The results of the analysis and determination of the possibility of providing innovation development are interpreted on the example of Farmak JSC as it is one of the leading pharmaceutical industry companies. The economic data of the company, financial-economic analysis elements and determination of the financial stability degree with the help of the fuzzy logic apparatus were used for the research. The article confirmed the idea of the importance of investing in technological innovation. Directions of potential future researches are determined

Holstein polaron in the presence of disorder

Non-local, inhomogeneous and retarded response observed in experiments is reproduced by introducing the Inhomogeneous Momentum Average (IMA) method to study single polaron problems with disorder in the on-site potential and/or spatial variations of the electron-phonon couplings and/or phonon frequencies. We show that the electron-phonon coupling gives rise to an additional inhomogeneous, strongly retarded potential, which makes instant approximations questionable. The accuracy of IMA is demonstrated by comparison with results from the approximation free Diagrammatic Monte Carlo (DMC) method. Its simplicity allows for easy study of many problems that were previously unaccessible. As an example, we show how inhomogeneities in the electron-phonon coupling lead to nonlocal, retarded response in scanning tunneling microscopy (STM) images.Comment: 4 pages, 3 figure

Quantum Dynamics of the Hubbard-Holstein Model in Equilibrium and Non-Equilibrium: Application to Pump-Probe Phenomena

The spectral response and physical features of the 2D Hubbard-Holstein model are calculated both in equilibrium at zero and low chemical dopings, and after an ultra short powerful light pulse, in undoped systems. At equilibrium and at strong charge-lattice couplings, the optical conductivity reveals a 3-peak structure in agreement with experimental observations. After an ultra short pulse and at nonzero electron-phonon interaction, phonon and spin subsystems oscillate with the phonon period $T_{ph} \approx 80$ fs. The decay time of the phonon oscillations is about 150-200 fs, similar to the relaxation time of the charge system. We propose a criterion for observing these oscillations in high $T_c$ compounds: the time span of the pump light pulse $\tau_{pump}$ has to be shorter than the phonon oscillation period $T_{ph}$.Comment: 4 pages, 4 figure