Field Theories on Null Manifolds

We argue that generic field theories defined on null manifolds should have an emergent BMS or conformal Carrollian structure. We then focus on a simple interacting conformal Carrollian theory, viz. Carrollian scalar electrodynamics. We look at weak (on-shell) and strong invariance (off-shell) of its equations of motion under conformal Carrollian symmetries. Helmholtz conditions are necessary and sufficient conditions for a set of equations to arise from a Lagrangian. We investigate whether the equations of motion of Carrollian scalar electrodynamics satisfy these conditions. Then we proposed an action for the electric sector of the theory. This action is the first example for an interacting conformal Carrollian Field Theory. The proposed action respects the finite and infinite conformal Carrollian symmetries in d = 4. We calculate conserved charges corresponding to these finite and infinite symmetries and then rewrite the conserved charges in terms of the canonical variables. We finally compute the Poisson brackets for these charges and confirm that infinite Carrollian conformal algebra is satisfied at the level of charges

Smoothing for time-varying systems using measurements containing colored noise

Optimal smoother derived for linear time-varying systems using measurements containing colored noise by means of calculus of variation

Covariant EBK quantization of the electromagnetic two-body problem

We discuss a method to transform the covariant Fokker action into an implicit two-degree-of-freedom Hamiltonian for the electromagnetic two-body problem with arbitrary masses. This dynamical system appeared 100 years ago and it was popularized in the 1940's by the still incomplete Wheeler and Feynman program to quantize it as a means to overcome the divergencies of perturbative QED. Our finite-dimensional implicit Hamiltonian is closed and involves no series expansions. The Hamiltonian formalism is then used to motivate an EBK quantization based on the classical trajectories with a non-perturbative formula that predicts energies free of infinities.Comment: 21 page

The separate computation of arcs for optimal flight paths with state variable inequality constraints

Computation of arcs for optimal flight paths with state variable inequality constraint

Galilean Electrodynamics: Covariant formulation and Lagrangian

In this paper, we construct a single Lagrangian for both limits of Galilean electrodynamics. The framework relies on a covariant formalism used in describing Newton-Cartan geometry. We write down the Galilean conformal algebra and its representation in this formalism. We also show that the Lagrangian is invariant under the Galilean conformal algebra in d = 4 and calculate the energy-momentum tensor

Synthesis And Characterization Of ZnO Nanoparticles

In this paper, we report the comparison between ZnO nanoparticles prepared via two different routes; i) via sol-gel route and ii) by solid state reaction method. It was found that when prepared under the same ambient conditions viz temperature, pressure etc. and keeping all the parameters same viz precursors, molarity, solvent etc; the nanoparticles prepared via Sol-gel route were highly crystalline and had smaller crystallite size (~ 24 nm) as compared to the one prepared by Solid state reaction method (~ 37 nm). The crystallinity and the crystallite size were examined by XRD and TEM. Variation in the bandgap as a function of size of the particles was determined using the absorption spectra obtained by UV-Vis-NIR spectrophotometer. Photoluminescence (PL) was also recorded in the visible region for the two types of particles and results have been analysed. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/952

Wikitruth Through Wikiorder

How does large-scale social production coordinate individual behavior to produce public goods? Hardin (1968) denied that the creation of public goods absent markets or the State is possible. Benkler (2006), Shirky (2008), Zittrain (2008), and Lessig (2008) recently countered that the needed coordination might emerge though social norms. However, the means to this coordination is under-theorized. Focusing on Wikipedia, we argue that the site’s dispute resolution process is an important force in promoting the public good it produces, i.e., a large number of relatively accurate public encyclopedia articles. We describe the development and shape of Wikipedia’s existing dispute resolution system. Further, we present a statistical analysis based on coding of over 250 arbitration opinions from Wikipedia’s arbitration system. The data show that Wiki-dispute resolution ignores the content of user disputes, instead focusing on user conduct. Based on fairly formalized arbitration findings, we find a high correlation between the conduct found and the remedies ordered. In effect, the system functions not so much to resolve disputes and make peace between conflicting users, but to weed out problematic users while weeding potentially productive users back in to participate. Game theorists have modeled large scale social production as a solution to the herder problem/multi-player prisoner’s dilemma. But we demonstrate that the “weeding in” function reflects dynamics more accurately captured in coordination games instead. In this way, dispute resolution can provide a constitutive function for the community

Wikitruth Through Wikiorder

How does large-scale social production coordinate individual behavior to produce public goods? In 1968, Hardin denied that the creation of public goods absent markets or the State is possible. Benkler, Shirky, Zittrain, and Lessig recently countered that the necessary coordination might emerge though social norms. However, scholars have not fully explained how this coordination is to occur. Game theorists have modeled large-scale social production as a solution to the herder problem/multi-player Prisoner¿s Dilemma. But we demonstrate that the ¿weeding in function reflects dynamics more accurately captured in coordination games. In this way, dispute resolution can provide a constitutive function for the community

Field equations from a surface term

As is well known, in order for the Einstein--Hilbert action to have a well defined variation, and therefore to be used for deriving field equation through the stationary action principle, it has to be amended by the addition of a suitable boundary term. It has recently been claimed that, if one constructs an action by adding this term to the matter action, the Einstein field equations can be derived by requiring this action to be invariant under active transformations which are normal to a null boundary. In this paper we re-examine this approach both for the case of pure gravity and in the presence of matter. We show that in the first case this procedure holds for more general actions than the Einstein-Hilbert one and trace the basis of this remarkable attribute. However, it is also pointed out the when matter is rigorously considered the approach breaks down. The reasons for that are thoroughly discussed.Comment: Typos corrected, minor changes to match published versio