333 research outputs found
Bandwidth-controlled Mott transition in I. Optical studies of localized charge excitations
Infrared reflection measurements of the half-filled two-dimensional organic
conductors -(BEDT-TTF)Cu[N(CN)]BrCl were
performed as a function of temperature ( K) and
Br-substitution (, 40%, 73%, 85%, and 90%) in order to study the
metal-insulator transition. We can distinguish absorption processes due to
itinerant and localized charge carriers. The broad mid-infrared absorption has
two contributions: transitions between the two Hubbard bands and intradimer
excitations from the charges localized on the (BEDT-TTF) dimer. Since the
latter couple to intramolecular vibrations of BEDT-TTF, the analysis of both
electronic and vibrational features provides a tool to disentangle these
contributions and to follow their temperature and electronic-correlations
dependence. Calculations based on the cluster model support our interpretation.Comment: 12 pages, 12 figure
The Proactive Projects Management in the Seamen Training System
The article analyzes the status of seamen training in Ukraine. The main problems and directions of their solution as to training of seamen in the higher marine educational institutions (HMEI) are defined. The concepts of «proactivity» and «proactive management» are researched, the authors’ own understanding of proactive management in the system of seamen training is presented. In the proactive management, the first priority is the optimal combination of classical maritime education with computer technologies in such a way that the level of training becomes higher, the range of services is expanded, and the cost of provision of the educational services is reduced. According to the authors, the VR- and AR-technologies are at the forefront. It is emphasized that the financial side of implementation of proactive management requires very significant costs, but as a result, all stakeholders win, because these costs will ensure the use of the potential of existing opportunities in the global maritime market. It is determined that the introduction of proactive management in the system of seamen training will be active in case of establishing partnership between the HMEI and the shipping companies
Disentangling the conductivity spectra of two-dimensional organic conductors
The optical spectrum of a κ -phase organic conductor is thoroughly analyzed for the example of κ -(BEDT-TTF) 2 Cu [ N(CN) 2 ] Br 0.85 Cl 0.15 in order to identify its various contributions. It is shown how the complex spectra can be decomposed using different approaches; the intradimer and interdimer contributions are discussed. In particular the fingerprints of electronic correlations in these spectra are considered
Multiscale nature of hysteretic phenomena: Application to CoPt-type magnets
We suggest a workable approach for the description of multiscale
magnetization reversal phenomena in nanoscale magnets and apply it to CoPt-type
alloys. We show that their hysteretic properties are governed by two effects
originating at different length scales: a peculiar splitting of domain walls
and their strong pinning at antiphase boundaries. We emphasize that such
multiscale nature of hysteretic phenomena is a generic feature of nanoscale
magnetic materials.Comment: 4 pages (revtex 4), 2 color EPS figure
Charge-transfer processes in radical ion molecular conductors κ-(BEDT-TTF)2Cu[N(CN)2]Br x Cl1 − x : The superconductor (x = 0.9) and the conductor with the metal-insulator transition (x = 0)
Optical spectral investigations of low-dimensional organic molecular conductors κ-(BEDT-TTF)2Cu[N(CN)2]Br x Cl1 − x with x = 0.9 (the superconductor with T c = 11.3 K) and x = 0 (the metal with the metal-insulator transition at T < 50 K) are performed in the range 50–6000 cm−1 (6 meV–0.74 eV) at temperatures from 300 to 20 K. The optical conductivity spectra are quantitatively analyzed in terms of the proposed model, according to which the charge transfer involves two types of charge carriers, i.e., electrons (holes) localized on clusters (dimers and tetramers formed by BEDT-TTF molecules) and quasi-free charge carriers, with the use of the tetramer “cluster“ model based on the Hubbard Hamiltonian for correlated electrons and the Drude model for quasi-free charge carriers. Physical parameters of the model, such as the energy of Coulomb repulsion between two electrons (holes) in one molecule, the transfer integrals between molecules inside the dimer and between dimers, and the electron-molecular vibration coupling constants, are determined. The anisotropy of the spectra in the conducting plane is explained. The inference is made that only electrons localized on clusters couple with intramolecular vibrations
Оцінювання запасів прісної води півдня України
The method of determining available water resources and the volumes of their use are presented. The methodology uses indicators: water quantity and quality, variability, raising public awareness of water problems, access to water and vulnerability of ecosystems. On the basis of the «Atlas of Water Risk» (interactive map), based on the described method, an assessment of the availability of fresh water in southern regions of Ukraine was made using the example of data for the year 2015.Наведено методику визначення доступних водних ресурсів і обсягів їх використання за показниками кількості води, її мінливості та якості, підвищення обізнаності громадськістю про водні проблеми, доступу до води і уразливості екосистем. На базі «Атласу водного ризику» (інтерактивної карти) за описаною методикою проведено оцінювання забезпеченості південних регіонів України прісною водою на прикладі даних 2015 р
Genetic resources of narrow-leaved lupine (Lupinus angustifolius L.) and their role in its domestication and breeding
Narrow-leaved lupine (Lupinus angustifolius L.) is a cultivated multipurpose species with a very short history of domestication. It is used as a green manure, and for feed and food. This crop shows good prospects for use in pharmacology and as a source of fish feeds in aquaculture. However, its genetic potential for the development of productive and adaptable cultivars is far from being realized. For crop species, the genetic base of the cultivated gene pool has repeatedly been shown as being much narrower than that of the wild gene pool. Therefore, efficient utilization of a species’ genetic resources is important for the crop’s further improvement. Analyzing the information on the germplasm collections preserved in national gene banks can help perceive the worldwide diversity of L. angustifolius genetic resources and understand how they are studied and used. In this context, the data on the narrow-leaved lupine collection held by VIR are presented: its size and composition, the breeding status of accessions, methods of studying and disclosing intraspecific differentiation, the classifications used, and the comparison of this information with available data on other collections. It appeared that VIR’s collection of narrow-leaved lupine, ranking as the world’s second largest, differed significantly from others by the prevalence of advanced cultivars and breeding material in it, while wild accessions prevailed in most collections. The importance of the wild gene pool for the narrow-leaved lupine breeding in Australia, the world leader in lupine production, is highlighted. The need to get an insight into the species’ ecogeographic diversity in order to develop cultivars adaptable to certain cultivation conditions is shown. The data on the testing of VIR’s collection for main crop characters valuable for breeders are presented. Special attention is paid to the study of accessions with limited branching as a promising gene pool for cultivation in relatively northern regions of Russia. They demonstrate lower but more stable productivity, and suitability for cultivation in planting patterns, which has a number of agronomic advantages. Analyzing the work with narrow-leaved lupine genetic resources in different national gene banks over the world helps shape the prospects of further activities with VIR’s collection as the only source of promising material for domestic breeding
Laser Therapy in Correction of Optimization of Surgical Endointoxication
The problem of endointoxication remains one of the most urgent in modern surgery. The severity of the intoxication syndrome is determined not only by the intensity of the entry of toxic substances into the bloodstream from the lesion focus, but also by the adequacy of the functioning of the main mechanisms of detoxification - elimination of toxins. Clinical and laboratory studies of 62 patients with acute peritonitis were performed. To this end, daily sessions of laser therapy with “Matrix” were conducted for 5 days after the operation, using a head of KLO3 (radiation with a wavelength of 635 nm, 2 mW). Laser irradiation of blood through the skin in the projection of the ulnar vein was performed for 30 minutes. Using laser therapy for patients with acute peritonitis led to the reduction of the endogenous intoxication severity. The level of medium-mass molecules (λ = 280 nm) decreased by 13.3-26.2% compared to the control, the level of average-weight molecules (λ = 254 nm) decreased by 15.5-32.6% (p <0.05) against the background of laser therapy. Thus, the use of laser therapy in patients with acute peritonitis has led to a decrease in the severity of endogenous intoxication. One of the significant components of this treatment is its ability to improve microcirculation and, as a result, to correct lipid peroxidation and hypoxia, which reduces catabolic phenomena (one of the sources of endogenous intoxication). Clinical and laboratory studies have established that the effectiveness of such treatment decreases with severe forms of peritonitis
Effect of termostimulation on maize leaves’ biopotentials
Dynamics of maize leaves' biopotentials evoked by cold- and heat stimuli with two frequencies 0.05 and 0.1 Hz is analyzed. Potential amplitude dependence of heating rate and time interval between first and following stimuli during both heating and cooling was discovered. It is ascertained that following potentials' amplitude increases in time during heat stimulation and decreases in time during cold stimulation. Qualitative difference in the reaching of potential stabilization is established for both stimulation frequencies; and probable reasons of the difference are analyzed. Potential stabilization levels are fixed for each series of experiment
Modeling of influence of resourcing factors on gross regional product
The purpose of the study is to assess the degree of influence of key components of the region’s resource potential on the gross regional product per capita as the main recognized indicator of regional development and regional competitiveness based on building an econometric model with the subsequent development of a projection of changes in the indicator of a specific region under the influence of quality and quantity resource potentia
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