1,809 research outputs found
Quasilocal Conservation Laws: Why We Need Them
We argue that conservation laws based on the local matter-only
stress-energy-momentum tensor (characterized by energy and momentum per unit
volume) cannot adequately explain a wide variety of even very simple physical
phenomena because they fail to properly account for gravitational effects. We
construct a general quasi}local conservation law based on the Brown and York
total (matter plus gravity) stress-energy-momentum tensor (characterized by
energy and momentum per unit area), and argue that it does properly account for
gravitational effects. As a simple example of the explanatory power of this
quasilocal approach, consider that, when we accelerate toward a freely-floating
massive object, the kinetic energy of that object increases (relative to our
frame). But how, exactly, does the object acquire this increasing kinetic
energy? Using the energy form of our quasilocal conservation law, we can see
precisely the actual mechanism by which the kinetic energy increases: It is due
to a bona fide gravitational energy flux that is exactly analogous to the
electromagnetic Poynting flux, and involves the general relativistic effect of
frame dragging caused by the object's motion relative to us.Comment: 20 pages, 1 figur
Dirac versus Reduced Quantization of the Poincar\'{e} Symmetry in Scalar Electrodynamics
The generators of the Poincar\'{e} symmetry of scalar electrodynamics are
quantized in the functional Schr\"{o}dinger representation. We show that the
factor ordering which corresponds to (minimal) Dirac quantization preserves the
Poincar\'{e} algebra, but (minimal) reduced quantization does not. In the
latter, there is a van Hove anomaly in the boost-boost commutator, which we
evaluate explicitly to lowest order in a heat kernel expansion using zeta
function regularization. We illuminate the crucial role played by the gauge
orbit volume element in the analysis. Our results demonstrate that preservation
of extra symmetries at the quantum level is sometimes a useful criterion to
select between inequivalent, but nevertheless self-consistent, quantization
schemes.Comment: 24 page
Rectenna for high-voltage applications
An energy transfer system is disclosed. The system includes patch elements, shielding layers, and energy rectifying circuits. The patch elements receive and couple radio frequency energy. The shielding layer includes at least one opening that allows radio frequency energy to pass through. The openings are formed and positioned to receive the radio frequency energy and to minimize any re-radiating back toward the source of energy. The energy rectifying circuit includes a circuit for rectifying the radio frequency energy into dc energy. A plurality of energy rectifying circuits is arranged in an array to provide a sum of dc energy generated by the energy rectifying circuit
Electoral turnover has very little effect on the spending habits of Western democracies
Do new electoral brooms sweep clean the economic policies of the parties that went before? In new research that examines how incoming Western governments set their spending priorities, Derek A. Epp, John Lovett, and Frank R. Baumgartner find that budgets tend to be set with little regard to a government’s ideology, be it left or right. They argue that when setting budgets, incoming policymakers are constrained by social, economic and international realities that are largely beyond their control. This means that budgets are set consistently and inconsistently with what went before at roughly the same rate; left-wing parties do not necessarily favor “big government” nor to right parties always seek to reduce government spending
The horizon and its charges in the first order gravity
In this work the algebra of charges of diffeomorphisms at the horizon of
generic black holes is analyzed within first order gravity. This algebra
reproduces the algebra of diffeomorphisms at the horizon, (Diff(S^1)), without
central extension
Do Bills of rights matter? The Canadian Charter of Rights and Freedoms
Although constitutional protection for rights is increasingly popular, there is little systematic research on the extent to which bills of rights affect the process of government. This article examines the effects a bill of rights may be expected to produce, and then uses a quasi-experimental design to analyze the effects of the Canadian Charter of Rights and Freedoms on the Canadian Supreme Court's agenda. The data suggest that the Charter indeed has influenced the Court's agenda, although the effects are more limited than generally recognized. More important, the data suggest that a number of the influences often attributed to the Charter likely resulted instead from the growth of what I call the support structure for legal mobilization, consisting of various resources that enable litigants to pursue rights-claims in court. The political significance of a bill of rights, then, depends on factors in civil society that are independent of constitutional structure
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