12,236 research outputs found
Periodic and Localized Solutions of the Long Wave-Short Wave Resonance Interaction Equation
In this paper, we investigate the (2+1) dimensional long wave-short wave
resonance interaction (LSRI) equation and show that it possess the Painlev\'e
property. We then solve the LSRI equation using Painlev\'e truncation approach
through which we are able to construct solution in terms of three arbitrary
functions. Utilizing the arbitrary functions present in the solution, we have
generated a wide class of elliptic function periodic wave solutions and
exponentially localized solutions such as dromions, multidromions, instantons,
multi-instantons and bounded solitary wave solutions.Comment: 13 pages, 6 figure
An Imaging and Spectral Study of Ten X-Ray Filaments around the Galactic Center
We report the detection of 10 new X-ray filaments using the data from the
{\sl Chandra} X-ray satellite for the inner ( parsec)
around the Galactic center (GC). All these X-ray filaments are characterized by
non-thermal energy spectra, and most of them have point-like features at their
heads that point inward. Fitted with the simple absorbed power-law model, the
measured X-ray flux from an individual filament in the 2-10 keV band is to ergs cm s and the
absorption-corrected X-ray luminosity is ergs s
at a presumed distance of 8 kpc to the GC. We speculate the origin(s) of these
filaments by morphologies and by comparing their X-ray images with the
corresponding radio and infrared images. On the basis of combined information
available, we suspect that these X-ray filaments might be pulsar wind nebulae
(PWNe) associated with pulsars of age yr. The fact
that most of the filament tails point outward may further suggest a high
velocity wind blowing away form the GC.Comment: 29 pages with 7 figures and 3 pages included. Accepted to Ap
Global axisymmetric stability analysis for a composite system of two gravitationally coupled scale-free discs
In a composite system of gravitationally coupled stellar and gaseous discs,
we perform linear stability analysis for axisymmetric coplanar perturbations
using the two-fluid formalism. The background stellar and gaseous discs are
taken to be scale-free with all physical variables varying as powers of
cylindrical radius with compatible exponents. The unstable modes set in as
neutral modes or stationary perturbation configurations with angular frequency
.Comment: 7 pages using AAS styl
Current-Controlled Negative Differential Resistance due to Joule Heating in TiO2
We show that Joule heating causes current-controlled negative differential
resistance (CC-NDR) in TiO2 by constructing an analytical model of the
voltage-current V(I) characteristic based on polaronic transport for Ohm's Law
and Newton's Law of Cooling, and fitting this model to experimental data. This
threshold switching is the 'soft breakdown' observed during electroforming of
TiO2 and other transition-metal-oxide based memristors, as well as a precursor
to 'ON' or 'SET' switching of unipolar memristors from their high to their low
resistance states. The shape of the V(I) curve is a sensitive indicator of the
nature of the polaronic conduction.Comment: 13 pages, 2 figure
Perancangan Buku Pedoman Olahraga Basket Untuk Anak Usia 6-14 Tahun
Menjadi seorang pemain bola basket yang baik, harus memiliki skill dan fundamental bermain bola basket yang benar. Banyak anak-anak yang ingin belajar basket tapi kurang memahami dasar fundamental serta peraturan dalam bola basket. Apabila hal tersebut terus berlanjut, maka kualitas permainan pemain basket di Indonesia dapat semakin menurun. Karenanya, Penting untuk mengajarkan teknik-teknik dasar olahraga bola basket sejak usia dini. Perancangan buku pedoman tentang olahraga basket untuk anak-anak ini bermaksud untuk memberikan pengenalan kepada anak-anak tentang pengertian bola basket, sejarah bola basket hingga teknik-teknik dalam permainan bola basket. Dengan adanya buku ini diharapkan dapat menjadi satu media informasi yang menarik bagi anak sehingga dapat mengenalkan dan menginspirasi mereka tentang olahraga bola basket dan dapat memberikan pengetahuan serta teknik-teknik dalam permainan bola basket. Disamping menelaah buku-buku tentang basket juga wawancara terhadap para ahli di bidangnya
A turn-key Concept for active cancellation of Global Positioning System L3 Signal
We present a concept, developed at the National Astronomy and Ionosphere
Center (NAIC) at Arecibo, Puerto Rico, for active suppression of Global
Positioning System (GPS) signals in the 305 m dish radio receiver path prior to
backend processing. The subsystem does not require an auxiliary antenna and is
intended for easy integration with radio telescope systems with a goal of being
a turnkey addition to virtually any facility. Working with actual sampled
signal data, we have focused on the detection and cancellation of the GPS L3
signal at 1381.05 MHz which, during periodic test modes and particularly during
system-wide tests, interfere with observations of objects in a range of
redshifts that includes the Coma supercluster, for example. This signal can
dynamically change modulation modes and our scheme is capable of detecting
these changes and applying cancellation or sending a blanking signal, as
appropriate. The subsystem can also be adapted to GPS L1 (1575.42 MHz), L2C
(1227.6 MHz), and others. A follow-up is underway to develop a prototype to
deploy and evaluate at NAIC.Comment: Presented at the RFI mitigation workshop, 29-31 March 2010,
Groningen, the Netherlands. Accepted for publication by the Proceedings of
Scienc
Spin injection from perpendicular magnetized ferromagnetic -MnGa into (Al,Ga)As heterostructures
Electrical spin injection from ferromagnetic -MnGa into an (Al,Ga)As
p-i-n light emitting diode (LED) is demonstrated. The -MnGa layers show
strong perpendicular magnetocrystalline anisotropy, enabling detection of spin
injection at remanence without an applied magnetic field. The bias and
temperature dependence of the spin injection are found to be qualitatively
similar to Fe-based spin LED devices. A Hanle effect is observed and
demonstrates complete depolarization of spins in the semiconductor in a
transverse magnetic field.Comment: 4 pages, 3 figure
Effect of manganese doping on the size effect of lead zirconate titanate thin films and the extrinsic nature of dead layers
We have investigated the size effect in lead zirconate titanate (PZT) thin
films with a range of manganese (Mn) doping concentrations. We found that the
size effect in the conventional Pt/PZT/Pt thin-film capacitors could be
systematically reduced and almost completely eliminated by increasing Mn doping
concentration. The interfacial layer at the electrode-film interface appears to
disappear almost entirely for the PZT films with 2% Mn doping levels, confirmed
by the fits using the conventional in-series capacitor model. Our work
indicates that the size effect in ferroelectrics is extrinsic in nature,
supporting the work by Saad et al. Other implications of our results have also
been discussed. By comparing a variety of experimental studies in the
literature we propose a scenario that the dead layer between PZT (or barium
strontium titanate, BST) and metal electrodes such as Pt and Au might have a
defective pyrochlore/fluorite structure (possibly with a small portion of
ferroelectric perovskite phase).Comment: 21 pages, 6 figure
New variable separation approach: application to nonlinear diffusion equations
The concept of the derivative-dependent functional separable solution, as a
generalization to the functional separable solution, is proposed. As an
application, it is used to discuss the generalized nonlinear diffusion
equations based on the generalized conditional symmetry approach. As a
consequence, a complete list of canonical forms for such equations which admit
the derivative-dependent functional separable solutions is obtained and some
exact solutions to the resulting equations are described.Comment: 19 pages, 2 fig
Duality of positive and negative integrable hierarchies via relativistically invariant fields
It is shown that the relativistic invariance plays a key role in the study of
integrable systems. Using the relativistically invariant sine-Gordon equation,
the Tzitzeica equation, the Toda fields and the second heavenly equation as
dual relations, some continuous and discrete integrable positive hierarchies
such as the potential modified Korteweg-de Vries hierarchy, the potential
Fordy-Gibbons hierarchies, the potential dispersionless
Kadomtsev-Petviashvili-like (dKPL) hierarchy, the differential-difference dKPL
hierarchy and the second heavenly hierarchies are converted to the integrable
negative hierarchies including the sG hierarchy and the Tzitzeica hierarchy,
the two-dimensional dispersionless Toda hierarchy, the two-dimensional Toda
hierarchies and negative heavenly hierarchy. In (1+1)-dimensional cases the
positive/negative hierarchy dualities are guaranteed by the dualities between
the recursion operators and their inverses. In (2+1)-dimensional cases, the
positive/negative hierarchy dualities are explicitly shown by using the formal
series symmetry approach, the mastersymmetry method and the relativistic
invariance of the duality relations. For the 4-dimensional heavenly system, the
duality problem is studied firstly by formal series symmetry approach. Two
elegant commuting recursion operators of the heavenly equation appear naturally
from the formal series symmetry approach so that the duality problem can also
be studied by means of the recursion operators.Comment: 25 pages, 0 figures, submitted to JHE
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