445 research outputs found
Surface scattering velocities in III-nitride quantum well laser structures via the emission of hybrid phonons
We have theoretically and numerically studied nitride-based quantum well (QW)
laser structures. More specifically, we have used a QW made with III-nitride
where the width of the barrier region is large relative to the electron mean
free path, and we have calculated the electron surface capture velocities by
considering an electron flux which is captured into the well region. The
process is assisted by the emission of the longitudinal optical phonons as
predicted by the hybrid (HB) model. The results of surface capture velocities
via the emission of HB phonons are compared to the emission of the dielectric
continuum phonons (Zakhleniuk et al 1999 Phys. Status Solidi a 176 79). Our
investigation shows that the two different phonon models predict almost the
same results for the non-retarded limit. Furthermore, the surface capture
velocities strongly depend on the size of the structure and the heterostructure
materials. Lastly, a comparison to the recent experimental values shows that
our model could accurately describe the experimentally measured parameters of
the quantum capture processes
Nonstandard work arrangements and configurations of firm and societal systems
In this study, we proposed and empirically confirmed that the use of nonstandard working arrangements (NSWAs) varies according to firm system and societal cluster. Utilizing the configurational, institutional and cultural perspectives, we explored antecedents to the use of four NSWAs across firms in six countries, expanding the scope of variables examined in relation to NSWAs and capturing context as a way of broadening the theory base on the subject. We found a tendency toward greater use of NSWAs among firm systems that foster internal socialization and career advancement over time as well as national contexts that promote employment protection and/or Institutional Collectivism. Finally, we found national context to be a significant determinant of firm system, reinforcing the importance of aligning national with organizational-level antecedents to the study of NSWAs. © 2015 Taylor & Francis
European security in the 1990s and beyond : the implications of the accession of Cyprus and Malta to the European Union
For the last decade, the dramatic events in eastern and central Europe have (rightly)
dominated the security debate in Europe and, indeed, the wider world. One of the
consequences of this has been that the traditional neglect of the Mediterranean region has
been compounded. However, there are now signs-notably the recent Barcelona conference
at which the European Union's Mediterranean policy was relaunched and extended (to incorporate the grand design of a Mediterranean free trade area) - that the Mediterranean is, at last, receiving some of the attention it deserves and justifies.peer-reviewe
Electronic structure of rectangular quantum dots
We study the ground state properties of rectangular quantum dots by using the
spin-density-functional theory and quantum Monte Carlo methods. The dot
geometry is determined by an infinite hard-wall potential to enable comparison
to manufactured, rectangular-shaped quantum dots. We show that the electronic
structure is very sensitive to the deformation, and at realistic sizes the
non-interacting picture determines the general behavior. However, close to the
degenerate points where Hund's rule applies, we find spin-density-wave-like
solutions bracketing the partially polarized states. In the
quasi-one-dimensional limit we find permanent charge-density waves, and at a
sufficiently large deformation or low density, there are strongly localized
stable states with a broken spin-symmetry.Comment: 8 pages, 9 figures, submitted to PR
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A framework for comparative institutional research on HRM
This article argues that awareness of institutional context has been singularly lacking in the most influential areas of HRM. This lack of attention to external context has resulted in findings that fail to reflect reality. We offer a layered contextual framework embedded in economic institutional theory. We propose that it forms the basis of a comparative research agenda for HRM. We validate the framework using extant publications on institutionally based comparative HRM, drawing on findings from the Cranet research network published in the decade 2007–2017
Investigation of the Unbalanced Magnetic Pull Damping Effect in Squirrel Cage Induction Machines
Static and Dynamic Lung Volumes in Swimmers and Their Ventilatory Response to Maximal Exercise
Purpose
While the static and dynamic lung volumes of active swimmers is often greater than the predicted volume of similarly active non-swimmers, little is known if their ventilatory response to exercise is also different.
Methods
Three groups of anthropometrically matched male adults were recruited, daily active swimmers (n = 15), daily active in fields sport (Rugby and Football) (n = 15), and recreationally active (n = 15). Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximal voluntary ventilation (MVV) was measured before and after exercise to volitional exhaustion.
Results
Swimmers had significantly larger FVC (6.2 ± 0.6 l, 109 ± 9% pred) than the other groups (5.6 ± 0.5 l, 106 ± 13% pred, 5.5 ± 0.8, 99% pred, the sportsmen and recreational groups, respectively). FEV1 and MVV were not different. While at peak exercise, all groups reached their ventilatory reserve (around 20%), the swimmers had a greater minute ventilation rate than the recreational group (146 ± 19 vs 120 ± 87 l/min), delivering this volume by breathing deeper and slower.
Conclusions
The swimmers utilised their larger static volumes (FVC) differently during exercise by meeting their ventilation volume through long and deep breaths
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