4,733 research outputs found
Dirichlet Boundary State in Linear Dilaton Background
Dirichlet-branes have emerged as important objects in studying
nonperturbative string theory. It is important to generalize these objects to
more general backgrounds other than the usual flat background. The simplest
case is the linear dilaton condensate. The usual Dirichlet boundary condition
violates conformal invariance in such a background. We show that by switching
on a certain boundary interaction, conformal invariance is restored. An
immediate application of this result is to two dimensional string theory.Comment: 6 pages, harvmac, some remarks are modified and one reference is
added, formulas remain the sam
Function generator eliminates necessity of series summation
Diode generator using four building-block circuits produces complex waveforms without the necessity of series summation. This highly specialized method of producing complex waveforms requires less power than present methods and uses simpler circuitry
Analyzing Demand For Disposal And Recycling Services: A Systems Approach
Pricing municipal solid waste (MSW) services using a flat fee offers no incentive to conserve on disposal. This has prompted the use of unit pricing schemes, which should reduce disposal in accordance with demand theory and encourage alternatives such as recycling. Most studies estimate distinct demand equations for disposal and recycling, and none use a systems approach to simultaneous estimate them. To that end, this research estimates such a model, which also recognizes the endogeneity of policy variables. The results offer important policy insight and shed light on the effectiveness of unit pricing in reducing disposal and simultaneously encouraging recycling.
Born-Infeld strings between D-branes
We examine the solutions of world-volume action for a D3-brane being put near
other D3-brane which is replaced by the background configuration of bulk space.
It is shown that the BPS solutions are not affected by the D3-brane background,
and they are interpreted as dyonic strings connecting two branes. On the
contrary, the non-BPS configurations are largely influenced by the background
D-brane, and we find that the solutions with pure electric charge cannot
connect two branes. These solutions are corresponding to the bound state of
brane and anti-brane which has been found by Callan and MaldacenaComment: 14 pages, 8 figure
Six-Dimensional Tensionless Strings In The Large N Limit
When five-branes of M-theory coincide the world-volume theory contains
tensionless strings, according to Strominger's construction. This suggests a
large limit of tensionless string theories. For the small instanton
theories, the definition would be a large instanton number. An adiabatic
argument suggests that in the large limit an effective extra uncompactified
dimension might be observed. We also propose ``surface-equations'', which are
an analog of Makeenko-Migdal loop-equations, and might describe correlators in
the tensionless string theories. In these equations, the anti-self-dual two
forms of 6D and the tensionless strings enter on an equal footing. Addition of
strings with CFTs on their world-sheet is analogous to addition of matter in 4D
QCD.Comment: 34 pages, LaTeX, 5 figures adde
S-Wave Scattering of Charged Fermions by a Magnetic Black Hole
We argue that, classically, -wave electrons incident on a magnetically
charged black hole are swallowed with probability one: the reflection
coefficient vanishes. However, quantum effects can lead to both electromagnetic
and gravitational backscattering. We show that, for the case of extremal,
magnetically charged, dilatonic black holes and a single flavor of low-energy
charged particles, this backscattering is described by a perturbatively
computable and unitary -matrix, and that the Hawking radiation in these
modes is suppressed near extremality. The interesting and much more difficult
case of several flavors is also discussed.Comment: 9p
Simulation study of intracity helicopter operations under instrument conditions to category 1 minimums
A fixed-base simulator study was conducted to define pilot workload and task performance associated with instrument flight operations for an intracity helicopter passenger service. Displays considered necessary to provide a minimal capability under Instrument Flight Rules conditions were used to fly a representative commercial helicopter route structure in the New York area, with each terminal assumed to be equipped with a precision approach guidance system. A cross section of pilots participated as test subjects, and despite the high workload level, the results indicated that for the assumptions employed, minimums of 61 m (200 ft) ceiling and 805 m (0.5 mile) visibility were feasible
Exact C=1 Boundary Conformal Field Theories
We present a solution of the problem of a free massless scalar field on the
half line interacting through a periodic potential on the boundary. For a
critical value of the period, this system is a conformal field theory with a
non-trivial and explicitly calculable S-matrix for scattering from the
boundary. Unlike all other exactly solvable conformal field theories, it is
non-rational ({\it i.e.} has infinitely many primary fields). It describes the
critical behavior of a number of condensed matter systems, including
dissipative quantum mechanics and of barriers in ``quantum wires''.Comment: harvmac, 10 pages, PUPT-1432/IASSNS-HEP-93/7
A grid-based infrastructure for distributed retrieval
In large-scale distributed retrieval, challenges of latency, heterogeneity, and dynamicity emphasise the importance of infrastructural support in reducing the development costs of state-of-the-art solutions. We present a service-based infrastructure for distributed retrieval which blends middleware facilities and a design framework to âliftâ the resource sharing approach and the computational services of a European Grid platform into the domain of e-Science applications. In this paper, we give an overview of the DILIGENT Search Framework and illustrate its exploitation in the ïŹeld of Earth Science
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