54,430 research outputs found
Dissecting the Interplay Between Elected Members and Officials in Board Level Technology Decisions: the case of a local authority in England
Digital investment and the successful selection and implementation of technology is crucial to local government success and yet there is a dearth of research evaluating how these decisions are made. And yet there is a dearth of research evaluating how Boards and executives of all kinds make these decisions and the role they play in influencing asset deployment in the digital space. In this regard, government, and especially local government is not only sparsely investigated as part of the existing body of knowledge but does not function neatly when compared to commercial organizations and the profit motive. This paper addresses the shortfall by investigating the interplay between elected members and Boards of local government in terms of complex decision-making processes surrounding technology investment. Empirically, this research adopts a case study approach and qualitative questioning of key elected and appointed actors allowing us to dissect the phenomenon
Fast moving of a population of robots through a complex scenario
Swarm robotics consists in using a large number of coordinated autonomous robots, or agents, to accomplish one or more tasks, using local and/or global rules. Individual and collective objectives can be designed for each robot of the swarm. Generally, the agents' interactions exhibit a high degree of complexity that makes it impossible to skip nonlinearities in the model. In this paper, is implemented both a collective interaction using a modified Vicsek model where each agent follows a local group velocity and the individual interaction concerning internal and external obstacle avoidance. The proposed strategies are tested for the migration of a unicycle robot swarm in an unknown environment, where the effectiveness and the migration time are analyzed. To this aim, a new optimal control method for nonlinear dynamical systems and cost functions, named Feedback Local Optimality Principle - FLOP, is applied
New measurements of magnetic fields of roAp stars with FORS1 at the VLT
Magnetic fields play a key role in the pulsations of rapidly oscillating Ap
(roAp) stars since they are a necessary ingredient of all pulsation excitation
mechanisms proposed so far. This implies that the proper understanding of the
seismological behaviour of the roAp stars requires knowledge of their magnetic
fields. However, the magnetic fields of the roAp stars are not well studied.
Here we present new results of measurements of the mean longitudinal field of
14 roAp stars obtained from low resolution spectropolarimetry with FORS1 at the
VLT.Comment: 5 pages, accepted for publication in A&
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Enhancing the Sensitivity of SMS Fiber Sensors by the Use of High Refractive Index Coatings
This paper presents a study on the behavior of single-mode/multimode/single-mode sensors with diamond-like carbon coating of high refractive index. Spectra and response for different values of the external medium refractive index are recorded and analyzed
High energy neutrino oscillation at the presence of the Lorentz Invariance Violation
Due to quantum gravity fluctuations at the Planck scale, the space-time
manifold is no longer continuous, but discretized. As a result the Lorentz
symmetry is broken at very high energies. In this article, we study the
neutrino oscillation pattern due to the Lorentz Invariance Violation (LIV), and
compare it with the normal neutrino oscillation pattern due to neutrino masses.
We find that at very high energies, neutrino oscillation pattern is very
different from the normal one. This could provide an possibility to study the
Lorentz Invariance Violation by measuring the oscillation pattern of very high
energy neutrinos from a cosmological distance.Comment: 11 pages, 6 figure
Atomic resolution mapping of phonon excitations in STEM-EELS experiments
Atomically resolved electron energy-loss spectroscopy experiments are
commonplace in modern aberrationcorrected transmission electron microscopes.
Energy resolution has also been increasing steadily with the continuous
improvement of electron monochromators. Electronic excitations however are
known to be delocalised due to the long range interaction of the charged
accelerated electrons with the electrons in a sample. This has made several
scientists question the value of combined high spatial and energy resolution
for mapping interband transitions and possibly phonon excitation in crystals.
In this paper we demonstrate experimentally that atomic resolution information
is indeed available at very low energy losses around 100 meV expressed as a
modulation of the broadening of the zero loss peak. Careful data analysis
allows us to get a glimpse of what are likely phonon excitations with both an
energy loss and gain part. These experiments confirm recent theoretical
predictions on the strong localisation of phonon excitations as opposed to
electronic excitations and show that a combination of atomic resolution and
recent developments in increased energy resolution will offer great benefit for
mapping phonon modes in real space
Violation of Energy Bounds in Designer Gravity
We continue our study of the stability of designer gravity theories, where
one considers anti-de Sitter gravity coupled to certain tachyonic scalars with
boundary conditions defined by a smooth function W. It has recently been argued
there is a lower bound on the conserved energy in terms of the global minimum
of W, if the scalar potential arises from a superpotential P and the scalar
reaches an extremum of P at infinity. We show, however, there are
superpotentials for which these bounds do not hold.Comment: 16 pages, 4 figures, v2: discussion of vacuum decay included, typos
corrected, reference adde
Blurred Lines Between Competition and Parasitism
Accurately describing the ecological relationships between species is more than mere semantics-doing so has profound practical and applied implications, not the least of which is that inaccurate descriptions can lead to fundamentally incorrect predicted outcomes of community composition and functioning. Accurate ecological classifications are particularly important in the context of global change, where species interactions can change rapidly following shifts in species composition. Here, we argue that many common ecological interactions-particularly competition and parasitism-can be easily confused and that we often lack empirical evidence for the full reciprocal interaction among species. To make our case and to propose a theoretical framework for addressing this problem, we use the interactions between lianas and trees, whose outcomes have myriad implications for the ecology and conservation of tropical forests (e.g., Schnitzer et al. 2015)
The Role of Fission in Neutron Star Mergers and Its Impact on the r-Process Peaks
Comparing observational abundance features with nucleosynthesis predictions of stellar evolution or explosion simulations, we can scrutinize two aspects: (a) the conditions in the astrophysical production site and (b) the quality of the nuclear physics input utilized. We test the abundance features of r-process nucleosynthesis calculations for the dynamical ejecta of neutron star merger simulations based on three different nuclear mass models: The Finite Range Droplet Model, the (quenched version of the) Extended Thomas Fermi Model with Strutinsky Integral, and the Hartree-Fock-Bogoliubov mass model. We make use of corresponding fission barrier heights and compare the impact of four different fission fragment distribution models on the final r-process abundance distribution. In particular, we explore the abundance distribution in the second r-process peak and the rare-earth sub-peak as a function of mass models and fission fragment distributions, as well as the origin of a shift in the third r-process peak position. The latter has been noticed in a number of merger nucleosynthesis predictions. We show that the shift occurs during the r-process freeze-out when neutron captures and β-decays compete and an (n,γ)-(γ,n) equilibrium is no longer maintained. During this phase neutrons originate mainly from fission of material above A = 240. We also investigate the role of β-decay half-lives from recent theoretical advances, which lead either to a smaller amount of fissioning nuclei during freeze-out or a faster (and thus earlier) release of fission neutrons, which can (partially) prevent this shift and has an impact on the second and rare-earth peak as well.Peer reviewe
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