Exchange-correlation effects in semiconductor double-quantum-wire systems

We study the short-range correlations in a double-quantum-wire structure within the self-consistent scheme of Singwi, Tosi, Land, and Sjolander. The local-field factors and static correlation functions are calculated for electron and electron-hole double-wire systems. The ground-state energy and collective excitations are discussed. It is found that the interwire correlations become quite important for electron-hole systems. Comparisons with the random-phase approximation and Hubbard approximation are made for various calculated quantities

Collective excitations and instabilities in double-wire electron-hole systems

We investigate the collective excitations in a double-wire system of spatially separated electrons and holes. Self-consistent local-field factors are used to describe the exchange-correlation effects at low densities. Plasmon dispersions and the dynamic structure factor S(q, w) are studied. Charge-density-wave instabilities in these structures are examined within the linear response theory at small and finite q-values

Correlation between clinical performance and degree of conversion of resin cements: a literature review

AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used

Genome-wide identification and phenotypic characterization of seizure-associated copy number variations in 741,075 individuals

Copy number variants (CNV) are established risk factors for neurodevelopmental disorders with seizures or epilepsy. With the hypothesis that seizure disorders share genetic risk factors, we pooled CNV data from 10,590 individuals with seizure disorders, 16,109 individuals with clinically validated epilepsy, and 492,324 population controls and identified 25 genome-wide significant loci, 22 of which are novel for seizure disorders, such as deletions at 1p36.33, 1q44, 2p21-p16.3, 3q29, 8p23.3-p23.2, 9p24.3, 10q26.3, 15q11.2, 15q12-q13.1, 16p12.2, 17q21.31, duplications at 2q13, 9q34.3, 16p13.3, 17q12, 19p13.3, 20q13.33, and reciprocal CNVs at 16p11.2, and 22q11.21. Using genetic data from additional 248,751 individuals with 23 neuropsychiatric phenotypes, we explored the pleiotropy of these 25 loci. Finally, in a subset of individuals with epilepsy and detailed clinical data available, we performed phenome-wide association analyses between individual CNVs and clinical annotations categorized through the Human Phenotype Ontology (HPO). For six CNVs, we identified 19 significant associations with specific HPO terms and generated, for all CNVs, phenotype signatures across 17 clinical categories relevant for epileptologists. This is the most comprehensive investigation of CNVs in epilepsy and related seizure disorders, with potential implications for clinical practice

Coupled plasmon-LO-phonon modes in GaInAs quantum wires

We study the collective excitation modes of coupled quasi-one-dimensional electron gas and longitudinal-optical phonons in GaInAs quantum wires within the random-phase approximation. In contrast to the higher-dimensional systems, the plasmon-phonon coupling is found to be strong at all linear carrier densities of interest. We calculate the oscillator strength of the numerically evaluated coupled modes and the Raman scattering intensity. The effect of phenomenological LO-phonon broadening on the collective excitation spectrum is also investigated. © 1996 American Institute of Physics

Spin correlations in electron liquids: Analytical results for the local-field correction in two and three dimensions

71.10.-w Theories and models of many electron systems , - 71.45.Gm Exchange, correlation, dielectric and magnetic functions, plasmons , - 73.20.Dx Electron states in low-dimensional structures (superlattices, quantum well structures and mutlilayers),

Ground-state correlations in semiconductor double-quantum-wire systems

We study the short-range correlations in a double-quantum-wire structure within the self-consistent scheme of Singwi et al. [Phys. Rev. 179, 589 (1968)]. The local-field factors and static correlation functions are calculated for electron and electron-hole double-wire systems. The ground-state energy and collective excitations are discussed. It is found that the interwire correlations become quite important for electron-hole systems

Ground-state correlations in semiconductor double-quantum-wire systems

[No abstract available