Search results for "special class"
showing 10 items of 20 documents
The Heisenberg dynamics of spin systems: A quasi*‐algebras approach
1996
The problem of the existence of the thermodynamical limit of the algebraic dynamics for a class of spin systems is considered in the framework of a generalized algebraic approach in terms of a special class of quasi*-algebras, called CQ*-algebras. Physical applications to (almost) mean-field models and to bubble models are discussed. © 1996 American Institute of Physics.
Chiral polyisocyanates, a special class of helical polymers
2001
Abstract Polyisocyanates (nylon 1) offer a lot of fascinating properties due to their dynamic helical conformation, which gives rise to orientational phenomena (large persistence length) or chiral amplification. This paper summarizes new results on polyisocyanates that appeared after the review by Bur and Fetters [Chem Rev 76 (1976) 727]. It starts with an overview of new synthetic methods, and then describes chiral polyisocyanates, their properties and the theoretical concepts developed to understand the experimental findings. Thereafter concentrated solutions (gels and LC phases) as well as photochromic polyisocyanates are discussed in detail. Finally, solid phase composite materials from…
Anti-phase wave patterns in a ring of electrically coupled oscillatory neurons
2013
International audience; Space-time dynamics of the network system modeling collective behavior of electrically coupled nonlinear cells is investigated. The dynamics of a local cell is described by the dimensionless Morris-Lecar system. It is shown that such a system yields a special class of traveling localized collective activity so called "anti-phase wave patterns". The mechanisms of formation of the patterns are discussed and the region of their existence is obtained by using the weakly coupled oscillators theory.
Anisotropic deformations in a class of projectively-invariant metric-affine theories of gravity
2020
Among the general class of metric-affine theories of gravity, there is a special class conformed by those endowed with a projective symmetry. Perhaps the simplest manner to realise this symmetry is by constructing the action in terms of the symmetric part of the Ricci tensor. In these theories, the connection can be solved algebraically in terms of a metric that relates to the spacetime metric by means of the so-called deformation matrix that is given in terms of the matter fields. In most phenomenological applications, this deformation matrix is assumed to inherit the symmetries of the matter sector so that in the presence of an isotropic energy-momentum tensor, it respects isotropy. In th…
�ber die Minimall�sung der Poincar�-Perronschen Differenzengleichung
1991
This paper deals with a special class of solutions of the higher order linear difference equation. It is shown that the minimal solution of Poincare-Perron type equations can be expressed in terms of generalized continued fractions.
2003
In this article we apply the S(M, g)–calculus of L. Hormander and, in particular, results concerning the spectral invariance of the algebra of operators of order zero in ℒ(L2(ℝn)) to study generators of Feller semigroups. The core of the article is the proof of the invertibility of λ Id + P for a strongly elliptic operator P in Ψ(M, g) and suitable weight functions M and metrics g. The proof depends highly on precise estimates of the remainder term in asymptotic expansions of the product symbol in Weyl and Kohn–Nirenberg quantization. Due to the Hille–Yosida–Ray theorem and a theorem of Courrege, the result concerning the invertibility of λ Id + P is applicable to obtain sufficient conditio…
Heterocycle-appended porphyrins: synthesis and challenges
2020
Abstract Porphyrin and their versatile metal complexes represent a special class of coordination compounds possessing unique physical-chemical properties. The achievements in the development of the synthetic approaches for the modification of the porphyrin macrocycle allowed the preparation of a variety of functional derivatives for diverse applications. Among a broad diversity of synthetically available metalloporphyrins meso-substituted tetrapyrroles are comprehensively investigated. However, β-substituted porphyrins could be considered as the most suitable models for mimicking the key roles of naturally occurring dyes in vital processes. The introduction of various substituents to the β-…
Socio-emotional Problems Experienced by Deaf and Hard of Hearing Students in Ethiopia
2015
This study compares the socio-emotional problems experienced by deaf and hard of hearing (DHH) students with those of hearing students in Ethiopia. The research involved a sample of 103 grade 4 students attending a special school for the deaf, a special class for the deaf and a regular school. Socio-emotional problems were measured using Goodman's self-report measure, the Strengths and Difficulties Questionnaire for children and adolescents. Participants were selected from seven towns in Ethiopia. The results show that, compared to the hearing sample, the DHH students experienced more severe socio-emotional problems across all dimensions, regardless of whether they were in special classes o…
Academic achievement and self-concept of deaf and hard-of-hearing and hearing students transitioning from the first to second cycle of primary school…
2018
ABSTRACTThis study was done to examine the transition of deaf and hard-of-hearing (DHH) and hearing students from the first cycle (Grade 4) to the second cycle (Grade 5) of primary education in Ethiopia. Academic achievement and self-concept were measured longitudinally with 103 DHH and hearing students. Participants were selected from three different settings (special schools, special classes and regular schools). Self-Description Questionnaire I (Marsh, H. W. 1990. Self-Description Questionnaire – I (SDQ I). Manual. MacArthur, NSW, Australia: University of Western Sydney) was used to measure the children’s self-concept. The results showed a decrease in the academic achievement and academi…