219 research outputs found
Kiwi talent flow : a study of chartered accountants and business professionals overseas
New Zealanders have always had a propensity to travel overseas. The globalisation of the
world has seen an increase in the number of people who, having completed their education and
gained some work experience, set off on their overseas experience. Concern has been
expressed as to the potential “brain drain” that would result should these well-educated and
talented citizens remain overseas permanently. This research considers the propensity to
return of over 1,500 expatriate Kiwis working in the areas of accounting and finance. It
examines their demographics, attitudes, values, motivations, factors of attraction to, and
repulsion from, New Zealand and their concerns for change in New Zealand. It therefore
provides insights into the nature and purpose of this significant group of professionals resident
mainly in the United Kingdom and Australia. We find that less than half are likely to return to
New Zealand. This is because of the lack of career and business opportunities despite the
“pull” of family and relations in New Zealand
Variational solution of the T-matrix integral equation
We present a variational solution of the T-matrix integral equation within a
local approximation. This solution provides a simple form for the T matrix
similar to Hubbard models but with the local interaction depending on momentum
and frequency. By examining the ladder diagrams for irreducible polarizability,
a connection between this interaction and the local-field factor is
established. Based on the obtained solution, a form for the T-matrix
contribution to the electron self-energy in addition to the GW term is
proposed. In the case of the electron-hole multiple scattering, this form
allows one to avoid double counting.Comment: 7 pages, 7 figure
Experimental time-resolved photoemission and ab initio study of lifetimes of excited electrons in Mo and Rh
We have studied the relaxation dynamics of optically excited electrons in
molybdenum and rhodium by means of time resolved two-photon photoemission
spectroscopy (TR-2PPE) and ab initio electron self-energy calculations
performed within the GW and GW+T approximations. Both theoretical approaches
reproduce qualitatively the experimentally observed trends and differences in
the lifetimes of excited electrons in molybdenum and rhodium. For excitation
energies exceeding the Fermi energy by more than 1 eV, the GW+T theory yields
lifetimes in quantitative agreement with the experimental results. As one of
the relevant mechanisms causing different excited state lifetime in Mo and Rh
we identify the occupation of the 4d bands. An increasing occupation of the 4d
bands results in an efficient decrease of the lifetime even for rather small
excitation energies of a few 100 meV.Comment: 8 pages, 10 figure
Mechanical properties of mesoporous ceria nanoarchitectures
Architectural constructs are engineered to impart desirable mechanical properties facilitating bridges spanning a thousand meters and buildings nearly 1 km in height. However, do the same 'engineering-rules' translate to the nanoscale, where the architectural features are less than 0.0001 mm in size? Here, we calculate the mechanical properties of a porous ceramic functional material, ceria, as a function of its nanoarchitecture using molecular dynamics simulation and predict its yield strength to be almost two orders of magnitude higher than the parent bulk material. In particular, we generate models of nanoporous ceria with either a hexagonal or cubic array of one-dimensional pores and simulate their responses to mechanical load. We find that the mechanical properties are critically dependent upon the orientation between the crystal structure (symmetry, direction) and the pore structure (symmetry, direction). This journal i
Strong polarization-induced reduction of addition energies in single-molecule nanojunctions
We address polarization-induced renormalization of molecular levels in
solid-state based single-molecule transistors and focus on an organic conjugate
molecule where a surprisingly large reduction of the addition energy has been
observed. We have developed a scheme that combines a self-consistent solution
of a quantum chemical calculation with a realistic description of the screening
environment. Our results indeed show a large reduction, and we explain this to
be a consequence of both (a) a reduction of the electrostatic molecular
charging energy and (b) polarization induced level shifts of the HOMO and LUMO
levels. Finally, we calculate the charge stability diagram and explain at a
qualitative level general features observed experimentally.Comment: 9 pages, 5 figure
Dynamic image potential at an Al(111) surface
We evaluate the electronic self-energy Sigma(E) at an Al(111) surface using the GW space-time method. This self-energy automatically includes the image potential V-im not present in any local-density approximation for exchange and correlation. We solve the energy-dependent quasiparticle equations and calculate the effective local potential experienced by electrons in the near-surface region. The relative contribution of exchange proves to be very different for states above the Fermi level. The image-plane position for interacting electrons is closer to the surface than for the purely electrostatic effects felt by test charges, and, like its classical counterpart, is drawn inwards by the effects of atomic structure
Kiwi talent flow: A study of chartered accountants and business professionals overseas
ABSTRACT New Zealanders have always had a propensity to travel overseas. The globalisation of the world has seen an increase in the number of people who, having completed their education and gained some work experience, set off on their overseas experience. Concern has been expressed as to the potential "brain drain" that would result should these well-educated and talented citizens remain overseas permanently. This research considers the propensity to return of over 1,500 expatriate Kiwis working in the areas of accounting and finance. It examines their demographics, attitudes, values, motivations, factors of attraction to, and repulsion from, New Zealand and their concerns for change in New Zealand. It therefore provides insights into the nature and purpose of this significant group of professionals resident mainly in the United Kingdom and Australia. We find that less than half are likely to return to New Zealand. This is because of the lack of career and business opportunities despite the "pull" of family and relations in New Zealand
Broadband conversion of microwaves into propagating spin waves in patterned magnetic structures
We have used time-resolved scanning Kerr microscopy and micromagnetic simulations to demonstrate that, when driven by the spatially uniform microwave field, the edges of patterned magnetic samples represent both efficient and highly tunable sources of propagating spin waves. The excitation is due to the local enhancement of the resonance frequency induced by the non-uniform dynamic demagnetizing field generated by precessing magnetization aligned with the edges. Our findings represent a crucial step forward in the design of nanoscale spin-wave sources for magnonic architectures and are also highly relevant to the understanding and interpretation of magnetization dynamics driven by spatially uniform magnetic fields in patterned magnetic samples
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