4,227 research outputs found
Counterterms in Gravity in the Light-Front Formulation and a D=2 Conformal-like Symmetry in Gravity
In this paper we discuss gravity in the light-front formulation (light-cone
gauge) and show how possible counterterms arise. We find that Poincare
invariance is not enough to find the three-point counterterms uniquely.
Higher-spin fields can intrude and mimic three-point higher derivative gravity
terms. To select the correct term we have to use the remaining
reparametrization invariance that exists after the gauge choice. We finally
sketch how the corresponding programme for N=8 Supergravity should work.Comment: 26 pages, references added, published versio
Critical currents for vortex defect motion in superconducting arrays
We study numerically the motion of vortices in two-dimensional arrays of
resistively shunted Josephson junctions. An extra vortex is created in the
ground states by introducing novel boundary conditions and made mobile by
applying external currents. We then measure critical currents and the
corresponding pinning energy barriers to vortex motion, which in the
unfrustrated case agree well with previous theoretical and experimental
findings. In the fully frustrated case our results also give good agreement
with experimental ones, in sharp contrast with the existing theoretical
prediction. A physical explanation is provided in relation with the vortex
motion observed in simulations.Comment: To appear in Physical Review
Spatiotemporal Stochastic Resonance in Fully Frustrated Josephson Ladders
We consider a Josephson-junction ladder in an external magnetic field with
half flux quantum per plaquette. When driven by external currents, periodic in
time and staggered in space, such a fully frustrated system is found to display
spatiotemporal stochastic resonance under the influence of thermal noise. Such
resonance behavior is investigated both numerically and analytically, which
reveals significant effects of anisotropy and yields rich physics.Comment: 8 pages in two columns, 8 figures, to appear in Phys. Rev.
Non-Gaussianity in Axion N-flation Models
We study perturbations in the multifield axion N-flation model, taking account of the full cosine potential. We find significant differences from previous analyses which made a quadratic approximation to the potential. The tensor-to-scalar ratio and the scalar spectral index move to lower values, which nevertheless provide an acceptable fit to observation. Most significantly, we find that the bispectrum non-Gaussianity parameter fNL may be large, typically of order 10 for moderate values of the axion decay constant, increasing to of order 100 for decay constants slightly smaller than the Planck scale. Such a non-Gaussian fraction is detectable. We argue that this property is generic in multifield models of hilltop inflation
Resonance Patterns in a Stadium-shaped Microcavity
We investigate resonance patterns in a stadium-shaped microcavity around
, where is the refractive index, the vacuum
wavenumber, and the radius of the circular part of the cavity. We find that
the patterns of high resonances can be classified, even though the
classical dynamics of the stadium system is chaotic. The patterns of the high
resonances are consistent with the ray dynamical consideration, and appears
as the stationary lasing modes with low pumping rate in the nonlinear dynamical
model. All resonance patterns are presented in a finite range of .Comment: 8 pages, 9 figure
Defect Motion and Lattice Pinning Barrier in Josephson-Junction Ladders
We study motion of domain wall defects in a fully frustrated
Josephson-unction ladder system, driven by small applied currents. For small
system sizes, the energy barrier E_B to the defect motion is computed
analytically via symmetry and topological considerations. More generally, we
perform numerical simulations directly on the equations of motion, based on the
resistively-shunted junction model, to study the dynamics of defects, varying
the system size. Coherent motion of domain walls is observed for large system
sizes. In the thermodynamical limit, we find E_B=0.1827 in units of the
Josephson coupling energy.Comment: 7 pages, and to apear in Phys. Rev.
A Recruitment and Human Resource Management Technique Using Blockchain Technology for Industry 4.0
Application of Information Technology (IT) in the domain of Human Resource
Management (HRM) systems is a sine qua non for any organization for
successfully adopting and implementing Fourth Industrial Revolution (Industry
4.0). However, these systems are required to ensure non-biased, efficient,
transparent and secure environment. Blockchain, a technology based on
distributed digital ledgers, can help facilitate the process of successfully
effectuating these specifications. A detailed literature review has been
conducted to identify the current status of usage of Information Technology in
the domain of Human Resource Management and how Blockchain can help achieve a
smart, cost-effective, efficient, transparent and secure factory management
system. A Blockchain based Recruitment Management System (BcRMS) as well as
Blockchain based Human Resource Management System (BcHRMS) algorithm have been
proposed. From the analysis of the results obtained through the case study, it
is evident that the proposed system holds definite advantages compared to the
existing recruitment systems. Future research directions have also been
identified and advocated.Comment: Onik, M. M. H., Miraz, M. H., & Kim, C. S. (2018, April). A
recruitment and human resource management technique using Blockchain
technology for Industry 4.0. In Proceedings of the Smart Cities Symposium
(SCS-2018), Manama, Bahrain (pp. 11-16). IE
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