70,027 research outputs found
Revelation of double magicity in N=Z nuclei in the rp-process region
In rapid-proton capture (rp-process), N=Z nuclei above Ni are understood to
act as waiting-point nuclei. The N=Z nuclei 68Se, 72Kr, 76Sr and 80Zr among
others are known to give rise to a large-energy x-ray flux and peaks in
abundances of these nuclei synthesized in the astrophysical rp-process.
Investigating the experimental isotope shifts in Kr isotopes near the proton
drip-line within the framework of the deformed Relativistic Hartree-Bogoliubov
theory, we have discovered that N=Z rp-process nuclei 68Se, 72Kr, 76Sr and 80Zr
exhibit large shell gap both at the proton and neutron numbers in the deformed
space with the consequence that pairing correlations for protons and neutrons
vanish. This lends a doubly magic character to these nuclei. A significant
number of nuclei in this region are also shown to exhibit neutron magicity at
N=34, 36, 38, and 40 in the deformed space. A unique case of concomitance of
the double magicity and the shape-coexistence is found for 68Se.Comment: 10 pages, 4 figures; Invited contribution presented at the
International Symposium on Exotic Nuclei, EXON 2009, Sochi, Russia, Sept.
28-Oct. 2, 200
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Clinical users' perspective on telemonitoring of patients with long term conditions: Understood through concepts of Giddens's structuration theory & consequence of modernity
This is the post-print version of the article - Copyright @ 2010 IOS.This study involves conducting focus group discussions with clinical users (nurses and technicians) prior to the launch of telehealth service in Nottingham, UK, to elicit their initial perceptions about the service. It describes the findings from preliminary phase of otherwise a larger longitudinal study. Using Giddens’s concepts from structuration theory and con-sequence of modernity, we were able to acknowledge trust and sense of security as two very salient aspects that govern adop-tion of new technological innovation. Unattended, these as-pects contribute to arousal of conflict and contradiction within a system. In order for successful telehealth implementa-tions in health care setting, providers of the service, need to focus on ways in which clinical users’ trust can be gained and sense of security can be promoted while using the telehealth service and technology.Funding was obained from MATCH (Multidisciplinary Assessment of Technologies Centre for Healthcare)
Firm corruption in the presence of an auditor
This paper develops a framework to explore firm corruption taking account of interaction with an auditor. The basic idea is that an auditor can provide auditing and other (consultancy) services. The extent of the other services depends on firm profitability. Hence auditor profitability can increase with firm corruption that may provide an incentive to collude in corrupt practices. This basic idea is developed using a game theoretic framework. It is shown that a multiplicity of equilibria exist from stable corruption, through auditor controlled corruption, via multiple equilibria to honesty on behalf of both actors. Following the development of the model various policy options are highlighted that show the difficulty of completely removing corrupt practices
Isospin Dependence of the Spin-Orbit Force and Effective Nuclear Potentials,
The isospin dependence of the spin-orbit potential is investigated for an
effective Skyrme-like energy functional suitable for density dependent
Hartree-Fock calculations. The magnitude of the isospin dependence is obtained
from a fit to experimental data on finite spherical nuclei. It is found to be
close to that of relativistic Hartree models. Consequently, the anomalous kink
in the isotope shifts of Pb nuclei is well reproduced.Comment: Revised, 11 pages (Revtex) and 2 figures available upon request,
Preprint MPA-833, Physical Review Letters (in press)
The microscopic origin of thermodynamic entropy in isolated systems
A microscopic understanding of the thermodynamic entropy in quantum systems
has been a mystery ever since the invention of quantum mechanics. In classical
physics, this entropy is believed to be the logarithm of the volume of phase
space accessible to an isolated system [1]. There is no quantum mechanical
analog to this. Instead, Von Neumann's hypothesis for the entropy [2] is most
widely used. However this gives zero for systems with a known wave function,
that is a pure state. This is because it measures the lack of information about
the system rather than the flow of heat as obtained from thermodynamic
experiments. Many arguments attempt to sidestep these issues by considering the
system of interest coupled to a large external one, unlike the classical case
where Boltzmann's approach for isolated systems is far more satisfactory. With
new experimental techniques, probing the quantum nature of thermalization is
now possible [3, 4]. Here, using recent advances in our understanding of
quantum thermalization [5-10] we show how to obtain the entropy as is measured
from thermodynamic experiments, solely from the self-entanglement of the
wavefunction, and find strong numerical evidence that the two are in agreement
for non-integrable systems. It is striking that this entropy, which is closely
related to the concept of heat, and generally thought of as microscopic chaotic
motion, can be determined for systems in energy eigenstates which are
stationary in time and therefore not chaotic, but instead have a very complex
spatial dependence.Comment: Manuscript is 5 pages, 2 figures, plus supplementary materials of 8
pages and 5 figure
On the design of optimal compliant walls for turbulence control
This paper employs the theoretical framework developed by Luhar et al. (J.
Fluid Mech., 768, 415-441) to consider the design of compliant walls for
turbulent skin friction reduction. Specifically, the effects of simple
spring-damper walls are contrasted with the effects of more complex walls
incorporating tension, stiffness and anisotropy. In addition, varying mass
ratios are tested to provide insight into differences between aerodynamic and
hydrodynamic applications. Despite the differing physical responses, all the
walls tested exhibit some important common features. First, the effect of the
walls (positive or negative) is greatest at conditions close to resonance, with
sharp transitions in performance across the resonant frequency or phase speed.
Second, compliant walls are predicted to have a more pronounced effect on
slower-moving structures because such structures generally have larger
wall-pressure signatures. Third, two-dimensional (spanwise constant) structures
are particularly susceptible to further amplification. These features are
consistent with many previous experiments and simulations, suggesting that
mitigating the rise of such two-dimensional structures is essential to
designing performance-improving walls. For instance, it is shown that further
amplification of such large-scale two-dimensional structures explains why the
optimal anisotropic walls identified by Fukagata et al. via DNS (J. Turb., 9,
1-17) only led to drag reduction in very small domains. The above observations
are used to develop design and methodology guidelines for future research on
compliant walls
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