7,854 research outputs found
Geodesic Motions in 2+1 Dimensional Charged Black Holes
We study the geodesic motions of a test particle around 2+1 dimensional
charged black holes. We obtain a class of exact geodesic motions for the
massless test particle when the ratio of its energy and angular momentum is
given by square root of cosmological constant. The other geodesic motions for
both massless and massive test particles are analyzed by use of numerical
method.Comment: 13page
Non-Quasinormal Modes and Black Hole Physics
The near-horizon geometry of a large class of extremal and near-extremal
black holes in string and M theory contains three-dimensional asymptotically
anti-de Sitter space. Motivated by this structure, we are led naturally to a
discrete set of complex frequencies defined in terms of the monodromy at the
inner and outer horizons of the black hole. We show that the correspondence
principle, whereby the real part of these ``non-quasinormal frequencies'' is
identified with certain fundamental quanta, leads directly to the correct
quantum behavior of the near-horizon Virasoro algebra, and thus the black hole
entropy. Remarkably, for the rotating black hole in five dimensions we also
reproduce the fractionization of conformal weights predicted in string theory.Comment: 4 pages, revtex4; v2: reference added; v3: more references, minor
typo corrected; v4: minor rewording to adjust size (ugh!); v5: some small
clarifications at referees' suggestio
Information Diffusion Power of Political Party Twitter Accounts During Japan's 2017 Election
In modern election campaigns, political parties utilize social media to
advertise their policies and candidates and to communicate to electorates. In
Japan's latest general election in 2017, the 48th general election for the
Lower House, social media, especially Twitter, was actively used. In this
paper, we perform a detailed analysis of social graphs and users who retweeted
tweets of political parties during the election. Our aim is to obtain accurate
information regarding the diffusion power for each party rather than just the
number of followers. The results indicate that a user following a user who
follows a political party account tended to also follow the account. This means
that it does not increase diversity because users who follow each other tend to
share similar values. We also find that followers of a specific party
frequently retweeted the tweets. However, since users following the user who
follow a political party account are not diverse, political parties delivered
the information only to a few political detachment users.Comment: The 10th International Conference on Social Informatics (SocInfo
2018
Higher Derivative Operators as Counterterms in Orbifold Compactifications
In the context of 5D N=1 supersymmetric models compactified on S_1/Z_2 or
S_1/(Z_2 x Z_2') orbifolds and with brane-localised superpotential, higher
derivative operators are generated radiatively as one-loop counterterms to the
mass of the (brane or zero mode of the bulk) scalar field. It is shown that the
presence of such operators which are brane-localised is not related to the
mechanism of supersymmetry breaking considered (F-term, discrete or continuous
Scherk-Schwarz breaking) and initial supersymmetry does not protect against the
dynamical generation of such operators. Since in many realistic models the
scalar field is commonly regarded as the Higgs field, and the higher derivative
operators seem a generic presence in orbifold compactifications, we stress the
importance of these operators for solving the hierarchy problem.Comment: Contribution to the Conference "Supersymmetry 2005", Durham; 13
pages, LaTe
Improvement of Fire Hydrant Design to Enhance Water Main Flushing
AbstractFlushing is a good practice to avoid problems related to sediment, bio-film growth, and corrosion. Artificial sediment was removed from fire hydrant with pilot scale water distribution main. The sediment removal in fire hydrant and main was carefully compared with different flow rate with velocity ranged from 0.3 to 3.0 m/s and the depth of fire hydrant from 0.5 m to 1.3m. The drain capability of fire hydrant decreased as the flow rate increased. Sediment with higher density was hard to remove from water main. The length effect of upward fire hydrant was relatively minor. Downward drain showed better efficiency for both sand and actual sediment
ESR Study of (C_5H_{12}N)_2CuBr_4
ESR studies at 9.27, 95.4, and 289.7 GHz have been performed on
(CHN)CuBr down to 3.7 K. The 9.27 GHz data were acquired
with a single crystal and do not indicate the presence of any structural
transitions. The high frequency data were collected with a polycrystalline
sample and resolved two absorbances, consistent with two crystallographic
orientations of the magnetic sites and with earlier ESR studies performed at
300 K. Below T, our data confirm the presence of a spin singlet
ground state.Comment: 2 pages, 4 figs., submitted 23rd International Conference on Low
Temperature Physics (LT-23), Aug. 200
Giant Gravitons in type IIA PP-wave Background
We examine giant gravitons with a worldvolume magnetic flux in type IIA
pp-wave background and find that they can move away from the origin along
direction in target space satisfying . This nontrivial relation can be
regarded as a complementary relation of the giant graviton on IIA pp-wave and
is shown to be connected to the spacetime uncertainty principle. The giant
graviton is also investigated in a system of N D0-branes as a fuzzy sphere
solution. It is observed that enters into the fuzzy algebra as a
deformation parameter. Such a background dependent Myers effect guarantees that
we again get the crucial relation of our giant graviton. In the paper, we also
find a BIon configuration on the giant graviton in this background.Comment: 10 pages, no figure, content added, typo corrected, reference adde
Exact solutions of Einstein and Einstein-scalar equations in 2 + 1 dimensions
A nonstatic and circularly symmetric exact solution of the Einstein equations
(with a cosmological constant and null fluid) in dimensions is
given. This is a nonstatic generalization of the uncharged spinless BTZ metric.
For , the spacetime is though not flat, the Kretschmann invariant
vanishes. The energy, momentum, and power output for this metric are obtained.
Further a static and circularly symmetric exact solution of the
Einstein-massless scalar equations is given, which has a curvature singularity
at and the scalar field diverges at as well as at infinity .Comment: 8 pages, Latex, no numbe
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