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

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

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

Mycobacterium tuberculosis type VII secretion system effectors differentially impact the ESCRT endomembrane damage response

Mycobacterium tuberculosis causes tuberculosis, which kills more people than any other infection. M. tuberculosis grows in macrophages, cells that specialize in engulfing and degrading microorganisms. Like many intracellular pathogens, in order to cause disease, M. tuberculosis damages the membrane-bound compartment (phagosome) in which it is enclosed after macrophage uptake. Recent work showed that when chemicals damage this type of intracellular compartment, cells rapidly detect and repair the damage, using machinery called the endosomal sorting complex required for transport (ESCRT). Therefore, we hypothesized that ESCRT might also respond to pathogen-induced damage. At the same time, our previous work showed that the EsxG-EsxH heterodimer of M. tuberculosis can inhibit ESCRT, raising the possibility that M. tuberculosis impairs this host response. Here, we show that ESCRT is recruited to damaged M. tuberculosis phagosomes and that EsxG-EsxH undermines ESCRT-mediated endomembrane repair. Thus, our studies demonstrate a battle between host and pathogen over endomembrane integrity.Intracellular pathogens have varied strategies to breach the endolysosomal barrier so that they can deliver effectors to the host cytosol, access nutrients, replicate in the cytoplasm, and avoid degradation in the lysosome. In the case of Mycobacterium tuberculosis, the bacterium perforates the phagosomal membrane shortly after being taken up by macrophages. Phagosomal damage depends upon the mycobacterial ESX-1 type VII secretion system (T7SS). Sterile insults, such as silica crystals or membranolytic peptides, can also disrupt phagosomal and endolysosomal membranes. Recent work revealed that the host endosomal sorting complex required for transport (ESCRT) machinery rapidly responds to sterile endolysosomal damage and promotes membrane repair. We hypothesized that ESCRTs might also respond to pathogen-induced phagosomal damage and that M. tuberculosis could impair this host response. Indeed, we found that ESCRT-III proteins were recruited to M. tuberculosis phagosomes in an ESX-1-dependent manner. We previously demonstrated that the mycobacterial effectors EsxG/TB9.8 and EsxH/TB10.4, both secreted by the ESX-3 T7SS, can inhibit ESCRT-dependent trafficking of receptors to the lysosome. Here, we additionally show that ESCRT-III recruitment to sites of endolysosomal damage is antagonized by EsxG and EsxH, both within the context of M. tuberculosis infection and sterile injury. Moreover, EsxG and EsxH themselves respond within minutes to membrane damage in a manner that is independent of calcium and ESCRT-III recruitment. Thus, our study reveals that T7SS effectors and ESCRT participate in a series of measures and countermeasures for control of phagosome integrity

Network Churn: The Effects of Self-Monitoring Personality on Brokerage Dynamics

The apparent stability of social network structures may mask considerable change and adjustment in the ties that make up the structures. In this study, we theorize and test-using longitudinal data on friendship relations from a radiology department located in the Netherlands-the idea that the characteristics of this "network churn" and the resultant brokerage dynamics are traceable to individual differences in self-monitoring personality. High self-monitors were more likely than low self-monitors to attract new friends and to occupy new bridging positions over time. In comparison to low self-monitors, the new friends that high self-monitors attracted tended to be relative strangers, in the sense that they were unconnected with previous friends, came from different functions, and more efficiently increased the number of structural holes in the resultant network. Our study suggests that dispositional forces help shape the dynamic structuring of networks: individuals help (re)create the social network structures they inhabit. © 2010 by Johnson Graduate School

Galilean Gauge Theories from Null Reductions

The procedure of null reduction provides a concrete way of constructing field theories with Galilean invariance. We use this to examine Galilean gauge theories, viz. Galilean electrodynamics and Yang-Mills theories in spacetime dimensions 3 and 4. Different non-relativistic conformal symmetries arise in these contexts: Schr{\"o}dinger symmetry in $d=3$ and Galilean conformal symmetry in $d=4$. A canonical analysis further reveals that the symmetries enhance to their infinite dimensional versions in phase space and pick up central extensions. In addition, for the Abelian theory, we discuss non-relativistic electro-magnetic duality in $d=3$ and its difference with the $d=4$ version. We also mention some quantum aspects for both Abelian and non-Abelian theories