scholarly journals Квазиклассическая модель статической электропроводности сильно легированных вырожденных полупроводников при низких температурах

2018 ◽  
Vol 52 (6) ◽  
pp. 544
Author(s):  
Н.А. Поклонский ◽  
С.А. Вырко ◽  
А.Н. Деревяго
Keyword(s):  
Indium Antimonide ◽  
Single Event ◽  
Mobility Edge ◽  
Spherical Region ◽  
Quasi Classical Approximation ◽  
Mobile Electron ◽  
Insulator Metal Transition ◽  
Wide Range ◽  
Electrostatic Fluctuations ◽  
Impurity Ion

AbstractGermanium, silicon, gallium arsenide, and indium antimonide n -type crystals on the metal side of the insulator–metal transition (Mott transition) are considered. In the quasi-classical approximation, the static (direct current) electrical conductivity and the drift mobility of electrons of the c band, and electrostatic fluctuations of their potential energy and the mobility edge are calculated. It is considered that a single event of the elastic Coulomb scattering of a mobile electron occurs only in a spherical region of the crystal matrix with an impurity ion at the center. The results of calculations using the proposed formulas without using fitting parameters are numerically consistent with experimental data in a wide range of concentrations of hydrogenlike donors at their weak and moderate compensation by acceptors.

What are serial verbs good for?

Serial Verbs ◽  
2018 ◽  
pp. 164-195
Author(s):  
Alexandra Y. Aikhenvald
Keyword(s):  
Single Event ◽  
Verbal Morphology ◽  
Serial Verb Constructions ◽  
Wide Range ◽  
Verb Constructions ◽  
Serial Verbs ◽  
Serial Verb ◽  
Good For

Serial verb constructions can express a multitude of grammatical meanings—including directionality, aspect, comparison, increasing valency, and many more. These meanings may be expressed with affixes in other languages. Using a serial verb may help express definiteness and focus. Detailed portrayal of various facets of one single event is a function of symmetrical serial verbs. Languages with serial verbs—or ‘serializing’ languages—are not exclusively associated with any particular type of language. Serial verbs are a major means of expressing grammatical meanings in languages with few if any bound morphemes. Many of these languages are highly analytic and isolating in their profile. Languages with little verbal morphology tend to rely on serial verbs for expressing the relevant meanings. Prolific use of serial verbs is a corollary of the language having a comparatively small number of verbs with a wide range of meanings.

A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - Damage to solids caused by cavitation

1966 ◽  
Vol 260 (1110) ◽  
pp. 245-255 ◽  
Keyword(s):  
Mechanical Properties ◽  
Cavitation Erosion ◽  
Cavitation Resistance ◽  
Steam Turbines ◽  
Single Event ◽  
Cavitation Damage ◽  
Erosion Damage ◽  
Highly Sensitive ◽  
Wide Range ◽  
The Impact

This paper describes the early stages of cavitation damage observed in cavitating venturi tunnels. The cavitating fluids were water and mercury, and a wide range of specimen materials were used. The damage was found to consist of single-event symmetical craters and irregular fatigue-type failures. The degree of damage was highly sensitive to minor flow perturbations, and this is discussed. The effect of stress level in the specimen before testing, and relations between cavitation resistance and the mechanical properties of the materials are considered.

Indium Antimonide (InSb) Focal Plane Array (FPA) Detection for Near-Infrared Imaging Microscopy

1994 ◽  
Vol 48 (5) ◽  
pp. 607-615 ◽  
Author(s):  
Patrick J. Treado ◽  
Ira W. Levin ◽  
E. Neil Lewis
Keyword(s):  
Indium Antimonide ◽  
High Speed ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Optical Microscope ◽  
Tunable Filter ◽  
Model Systems ◽  
High Spectral Resolution ◽  
Spectral Interval ◽  
Wide Range

Near-infrared spectroscopy is a sensitive, noninvasive method for chemical analyses, and its integration with imaging technologies represents a potent tool for the study of a wide range of materials. In this communication the use of an indium antimonide (InSb) multichannel imaging detector for near-infrared absorption spectroscopic microscopy is described. In particular, a 128 × 128 pixel InSb staring array camera has been combined with a refractive optical microscope and an acousto-optic tunable filter (AOTF) to display chemically discriminative, spatially resolved, vibrational spectroscopic images of biological and polymeric systems. AOTFs are computer-controlled bandpass filters that provide high speed, random wavelength access, wide spectral coverage, and high spectral resolution. Although AOTFs inherently have a wide range of spectroscopic applications, we apply this technology to NIR absorption microscopy between 1 and 2.5 μm. The spectral interval is well matched to the optical characteristics of both the NIR refractive microscope and the AOTF, thereby providing near-diffraction-limited performance with a practical spatial resolution of 1 to 2 μm. Design principles of this novel instrumentation and representative applications of the technique are presented for various model systems.

THE INFLUENCE OF NONLOCAL COULOMB INTERACTION ON GROUND-STATE PROPERTIES OF THE FALICOV–KIMBALL MODEL IN ONE AND TWO DIMENSIONS

2008 ◽  
Vol 22 (15) ◽  
pp. 2473-2487 ◽  
Author(s):  
HANA ČENČARIKOVÁ ◽  
PAVOL FARKAŠOVSKÝ ◽  
MARTIN ŽONDA
Keyword(s):  
Coulomb Interaction ◽  
Ground State ◽  
Occupation Number ◽  
Two Dimensions ◽  
Charge Ordering ◽  
Strong Interactions ◽  
Intermediate Coupling ◽  
Metal Insulator ◽  
Insulator Metal Transition ◽  
Wide Range

A combination of small-cluster exact diagonalizations and a well-controlled approximative method is used to study the ground states of the Falicov–Kimball model extended by nonlocal Coulomb interaction (U non ). It is shown that the ground-state phase diagram as well as the picture of valence and metal–insulator transitions found for the conventional Falicov–Kimball model are strongly changed when the nonlocal Coulomb interaction is added. This is illustrated for three selected values of the on-site Coulomb interaction (U) that represent typical behaviors of the model for small, intermediate and strong interactions. A number of remarkable results are found: (i) the phase separation takes place for a wide range of U non in all three interaction limits; (ii) in the weak and intermediate coupling limit, the model exhibits the nonlocal Coulomb interaction–induced insulator–metal transition; (iii) depending on the value of U non , the model is able to describe both the continuous and the discontinuous changes of the f-electron occupation number; (iv) new types of inhomogeneous charge ordering (including various types of axial and diagonal stripes) are observed for nonzero U non .

scholarly journals Repeated colonization of caves leads to phenotypic convergence in catfishes (Siluriformes: Trichomycterus) at a small geographical scale

2020 ◽  
Author(s):  
Juan Sebastián Flórez ◽  
Carlos Daniel Cadena ◽  
Carlos DoNascimiento ◽  
Mauricio Torres
Keyword(s):  
Dna Sequences ◽  
Population Level ◽  
Single Event ◽  
Undescribed Species ◽  
Behavioral Traits ◽  
The Andes ◽  
Wide Range ◽  
Geographical Scale ◽  
The Face ◽  
Phenotypic Convergence

ABSTRACTAcross various animal groups, adaptation to the extreme conditions of cave environments has resulted in convergent evolution of morphological, physiological, and behavioral traits. We document a Neotropical cave fish system with ample potential to study questions related to convergent adaptation to cave environments at the population level. In the karstic region of the Andes of Santander, Colombia, cave-dwelling catfishes in the genus Trichomycterus exhibit variable levels of reduction of eyes and body pigmentation relative to surface congeners. We tested whether cave-dwelling, eye reduced, depigmented Trichomycterus from separate caves in Santander were the result of a single event of cave colonization and subsequent dispersal, or of multiple colonizations to caves by surface ancestors followed by phenotypic convergence. Using mitochondrial DNA sequences to reconstruct phylogenetic relationships of Trichomycterus from Santander, we found that caves in this region have been colonized independently by two separate clades. Additional events of cave colonization -and possibly recolonization of surface streams- may have occurred in one of the clades, where surface and cave-dwelling populations exhibit shallow mtDNA differentiation, suggesting recent divergence or divergence in the face of gene flow. We also identified various taxonomic challenges including both a considerable number of potentially undescribed species and likely problems with the circumscription of named taxa. The system appears especially promising for studies on a wide range of ecological and evolutionary questions.

Neutron-Induced Single Event Effects Testing Across a Wide Range of Energies and Facilities and Implications for Standards

2006 ◽  
Vol 53 (6) ◽  
pp. 3596-3601 ◽  
Author(s):  
Clive Dyer ◽  
Alex Hands ◽  
Karen Ford ◽  
Adam Frydland ◽  
Peter Truscott
Keyword(s):  
Single Event ◽  
Single Event Effects ◽  
Wide Range

scholarly journals COMPARATIVE ANALYSIS OF THE INFLUENCE OF DOPING IONS OF YTTRIUM AND BORON FORMATION OF DEFECTS IN LITHIUM NIOBATE CRYSTALS

2021 ◽  
pp. 411-420
Author(s):  
Ольга Ростиславна Стародуб ◽  
Вячеслав Михайлович Воскресенский ◽  
Николай Васильевич Сидоров ◽  
Михаил Николаевич Палатников
Keyword(s):  
Comparative Analysis ◽  
Lithium Niobate ◽  
Nonlinear Optical ◽  
Photorefractive Effect ◽  
Ionic Radii ◽  
Wide Range ◽  
Impurity Ions ◽  
Unit Cells ◽  
Impurity Ion ◽  
Lithium Niobate Crystals

Кристалл ниобата лития, являющийся широко используемым и весьма востребованным в настоящее время нелинейно-оптическим материалом, примечателен своей способностью к варьирования широкого спектра сегнетоэлектрических и нелинейно-оптических характеристик в зависимости от типа и концентрации примесного иона, а также от соотношения Li / Nb . На основе разработанного нами подхода к моделированию кластеров в кристалле ниобата лития, в котором рост кластера идёт не элементарными ячейками, а кислородными октаэдрами, проведён сравнительный анализ особенностей внедрения в кристалл примесных ионов иттрия и бора с одинаковым зарядом +3 . Показано, что встраивание, вследствие различного ионного радиуса, идёт по двум механизмам: если для металла иттрия действует обычный механизм, когда примесной ион локализуется внутри кислородного октаэдра, то ион неметаллического элемента бора встраивается в тетраэдрические пустоты структуры, а именно в кислородные плоскости, образующие октаэдр. При этом влияние данных примесных ионов на одну из важнейших характеристик ниобата лития оказывается диаметрально противоположным: иттрий усиливает фоторефрактивный эффект, бор -понижает, что необходимо учитывать при направлении целевого использования кристаллов ниобата лития. Lithium niobate crystals, which are a widely used and highly demanded as nonlinear optical material, are remarkable for their ability to vary a wide range of ferroelectric and nonlinear optical characteristics depending on the type and concentration of the impurity ion, as well as on the Li / Nb ratio. Based on our approach to modeling clusters in the lithium niobate crystal, in which the cluster grows not by unit cells, but by oxygen octahedra, we have carried out a comparative analysis of the features of the incorporation of impurity ions of yttrium and boron with the same charge +3 into the crystal. It is shown that due to the different ionic radii the incorporation proceeds by to two mechanisms. If for yttrium the usual mechanism operates, when the impurity ion is localized inside the oxygen octahedron. The ion of boron, i.e. a nonmetallic element, is incorporated into the tetrahedral voids of the structure, namely, into the oxygen planes forming the octahedron. In this case, the influence of these impurity ions on one of the most important characteristics of lithium niobate turns out to be diametrically opposite: yttrium enhances the photorefractive effect, boron decreases it, which must be taken into account in the direction of targeted use of lithium niobate crystals.

scholarly journals Repeated colonization of caves leads to phenotypic convergence in catfishes (Siluriformes: Trichomycterus) at a small geographical scale

2021 ◽  
Author(s):  
Juan Sebastián Flórez ◽  
Carlos Daniel Cadena ◽  
Carlos Donascimiento ◽  
Mauricio Torres
Keyword(s):  
Dna Sequences ◽  
Convergent Evolution ◽  
Population Level ◽  
Single Event ◽  
Undescribed Species ◽  
The Andes ◽  
Wide Range ◽  
Geographical Scale ◽  
Divergence With Gene Flow ◽  
Phenotypic Convergence

Abstract Across various animal groups, adaptation to the challenging conditions of cave environments has resulted in convergent evolution. We document a Neotropical cavefish system with ample potential to study questions related to convergent adaptation to cave environments at the population level. In the karstic region of the Andes of Santander, Colombia, cave-dwelling catfish in the genus Trichomycterus exhibit variable levels of reduction of eyes and body pigmentation relative to surface congeners. We tested whether cave-dwelling, eye-reduced, depigmented Trichomycterus from separate caves in Santander were the result of a single event of cave colonization and subsequent dispersal, or of multiple colonizations to caves by surface ancestors followed by phenotypic convergence. Using mitochondrial DNA sequences to reconstruct phylogenetic relationships, we found that caves in this region have been colonized independently by two separate clades. Additional events of cave colonization – and possibly recolonization of surface streams – may have occurred in one of the clades, where surface and cave-dwelling populations exhibit shallow differentiation, suggesting recent divergence or divergence with gene flow. We also identify potentially undescribed species and likely problems with the circumscription of named taxa. The system appears promising for studies on a wide range of ecological and evolutionary questions.

scholarly journals Localization by an external magnetic field of electrons on the ions of hydrogen-like donors in non-degenerate semiconductors

2020 ◽  
Vol 56 (2) ◽  
pp. 239-252
Author(s):  
N. A. Poklonski ◽  
A. N. Dzeraviaha ◽  
S. A. Vyrko
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Indium Antimonide ◽  
Ionization Energy ◽  
Orbital Motion ◽  
Simple Analytical Expression ◽  
Degenerate Semiconductors ◽  
Conduction Electrons ◽  
Quasi Classical Approximation ◽  
The Magnetic Field

In the quasi-classical approximation of quantum mechanics a model for the localization of conduction electrons on the ions of hydrogen-like donors in an external magnetic field was developed. The thermal ionization energy of donors in lightly doped and moderately compensated crystals of gallium arsenide and indium antimonide of n-type was calculated depending on the induction of the external magnetic field. In contrast to the known theoretical works (which use variational methods for solving the Schrödinger equation), a simple analytical expression is proposed for the ionization energy of the donor in the magnetic field, which quantitatively agrees with the known experimental data. It is shown that the magnitude of the magnetic field induced by the orbital motion of the electron around the ion core of the donor is negligible compared to the external field and does not contribute to the ionization energy of donors.

scholarly journals Theoretical Investigation Of The Insulator-Metal Transition Point Of Nickel Monoxide

2016 ◽  
Vol 12 (15) ◽  
pp. 240
Author(s):  
Osarodion Ebomwonyi ◽  
John O. A. Idiodi
Keyword(s):  
Density Functional ◽  
Transition Point ◽  
Materials Science ◽  
Local Density ◽  
Metallic State ◽  
Insulator Metal Transition ◽  
The Density Functional Theory ◽  
Wide Range ◽  
Volume Compression ◽  
Murnaghan Equation

The study of the effects of applying high pressure by compression on materials is fundamental to a range of problems in condensed matter physics, materials science, technology, etc. Transition of an insulator into a metallic state is in general a basic phenomenon related to a wide range of physical systems. Nickel monoxide has been studied at different volume compression ratios by employing optical spectra and electronic structure calculations using the density functional theory implemented in the MindLab 5 code that made use of the local density approximation plus the Hubbard on-site Coulomb interaction parameter. Insulator-metal transition point was recorded at 0.60 volume compression ratio from both calculations and a transition pressure of 271 GPa was obtained using the Murnaghan equation of state.

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