30,224 research outputs found
Kondo resonance narrowing in d- and f-electron systems
By developing a simple scaling theory for the effect of Hund's interactions
on the Kondo effect, we show how an exponential narrowing of the Kondo
resonance develops in magnetic ions with large Hund's interaction. Our theory
predicts an exponential reduction of the Kondo temperature with spin S of the
Hund's coupled moment, a little-known effect first observed in d-electron
alloys in the 1960's, and more recently encountered in numerical calculations
on multi-band Hubbard models with Hund's interactions. We discuss the
consequences of Kondo resonance narrowing for the Mott transition in d-band
materials, particularly iron pnictides, and the narrow ESR linewidth recently
observed in ferromagnetically correlated f-electron materials.Comment: 4 pages, 3 figure
Residential sorting across Auckland neighbourhoods
This paper addresses the extent to which people in Auckland exhibit residential location patterns that differ between groups, i.e. the extent to which they are spatially sorted. To measure patterns of residential location, the paper uses the index of segregation, an isolation index, Gini coefficients, Ellison & Glaeser and Maurel & Sédillot concentration measures, Moran’s I and Getis and Ord’s G*. Results are presented based on a classification of the population in different ways: ethnicity, income, education, age and country of birth. Both city-wide and local measures are considered. We find that ethnic-based sorting is the strongest indicator of residential sorting patterns, but soring by income, education and age is also present. Sorting by income and qualifications is strongest at the top and, to lesser extent, at the bottom of the income and qualifications range. Age segregation is most pronounced for older residents. Clustering is strongest within a range of up to one kilometre and declines significantly over greater distances. Local analysis by means of Getis and Ord’s G* calculations suggest significant ethnic clustering. Apart from Maori and Pacific Islanders, ethnic groups tend to locate way from each other, as confirmed with cross-Moran’s I calculations. When considering interactions between ethnicity and income we find that the location of ethnicity income subgroups is more strongly related to neighbourhood income
Feasibility study of inlet shock stability system of YF-12
The feasibility of self actuating bleed valves as a shock stabilization system in the inlet of the YF-12 is considered for vortex valves, slide valves, and poppet valves. Analytical estimation of valve performance indicates that only the slide and poppet valves located in the inlet cowl can meet the desired steady state stabilizing flows, and of the two the poppet valve is substantially faster in response to dynamic disturbances. The poppet valve is, therefore, selected as the best shock stability system for the YF-12 inlet
Two-Dimensional Bosonization from Variable Shifts in the Path Integral
A method to perform bosonization of a fermionic theory in (1+1) dimensions in
a path integral framework is developed. The method relies exclusively on the
path integral property of allowing variable shifts, and does not depend on the
explicit form of Greens functions. Two examples, the Schwinger model and the
massless Thirring model, are worked out.Comment: 4 page
Strong magnetic fluctuations in superconducting state of CeCoIn
We show results on the vortex core dissipation through current-voltage
measurements under applied pressure and magnetic field in the superconducting
phase of CeCoIn. We find that as soon as the system becomes
superconducting, the vortex core resistivity increases sharply as the
temperature and magnetic field decrease. The sharp increase in flux flow
resistivity is due to quasiparticle scattering on critical antiferromagnetic
fluctuations. The strength of magnetic fluctuations below the superconducting
transition suggests that magnetism is complimentary to superconductivity and
therefore must be considered in order to fully account for the low-temperature
properties of CeCoIn.Comment: 7 pages, 6 figure
The role of procedural memory in grammar and numeracy skills
The objective of this study was to examine the contribution of procedural memory to grammar and numeracy skills, which both involve the manipulation of abstract patterns. Seventy-six typically developing children between 5 and 7 years of age were assessed on grammar with a past tense production task and a sentence comprehension task, on numeracy with a counting task and a calculation task, and on procedural memory with a serial reaction time task. Moderate correlations were found between the measures of grammar and numeracy. Moreover, 4 hierarchical linear regressions indicated that procedural memory was associated with calculation but not with counting or grammar skills when age and working memory were taken into account. These novel findings suggest that procedural memory may have a role to play in the development of some numeracy skills. Several possible explanations for the absence of contribution to grammar are considered
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