scholarly journals A variational method in the problem of screening an external charge in strongly correlated metals

2013 ◽  
Vol 103 (2) ◽  
pp. 27003 ◽  
Author(s):  
G. G. Guzmán-Verri ◽  
A. Shekhter ◽  
C. M. Varma
2002 ◽  
Vol 16 (26) ◽  
pp. 3895-3907 ◽  
Author(s):  
E. J. CALEGARI ◽  
S. G. MAGALHÃES ◽  
A. A. GOMES

The d–p band model, a periodic array of strongly correlated d states with hopping to a p band, and in the presence of a uniform applied magnetic field is studied as a function of temperature using Roth's variational method. Expanding the σ spin electron occupation numbers of d and p states to first order in the magnetic field h, we calculate the linear term of the field induced magnetization and thus the susceptibility. This is given in terms of the number of holes for La 2 - x Sr x CuO 4, in the limit of strongd–d correlations and we study the role of doping x and temperature "T" on the susceptibility.


1989 ◽  
Vol 54 (1) ◽  
pp. 101-105 ◽  
Author(s):  
J. Bruce Tomblin ◽  
Cynthia M. Shonrock ◽  
James C. Hardy

The extent to which the Minnesota Child Development Inventory (MCDI), could be used to estimate levels of language development in 2-year-old children was examined. Fifty-seven children between 23 and 28 months were given the Sequenced Inventory of Communication Development (SICD), and at the same time a parent completed the MCDI. In addition the mean length of utterance (MLU) was obtained for each child from a spontaneous speech sample. The MCDI Expressive Language scale was found to be a strong predictor of both the SICD Expressive scale and MLU. The MCDI Comprehension-Conceptual scale, presumably a receptive language measure, was moderately correlated with the SICD Receptive scale; however, it was also strongly correlated with the expressive measures. These results demonstrated that the Expressive Language scale of the MCDI was a valid predictor of expressive language for 2-year-old children. The MCDI Comprehension-Conceptual scale appeared to assess both receptive and expressive language, thus complicating its interpretation.


2019 ◽  
Author(s):  
Sam G. B. Roberts ◽  
Anna Roberts

Group size in primates is strongly correlated with brain size, but exactly what makes larger groups more ‘socially complex’ than smaller groups is still poorly understood. Chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) are among our closest living relatives and are excellent model species to investigate patterns of sociality and social complexity in primates, and to inform models of human social evolution. The aim of this paper is to propose new research frameworks, particularly the use of social network analysis, to examine how social structure differs in small, medium and large groups of chimpanzees and gorillas, to explore what makes larger groups more socially complex than smaller groups. Given a fission-fusion system is likely to have characterised hominins, a comparison of the social complexity involved in fission-fusion and more stable social systems is likely to provide important new insights into human social evolution


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