5,780 research outputs found
On the Sutherland's Integrability Condition for Two-Dimensional N-Particle Systems
Following Sutherland's work on one-dimensional integrable systems we
formulate and study its two-dimensional version. Physically it expresses the
absence of true 3-body forces among an assembly of N particles leaving
exclusively effective 2-body interactions. This criterion may be a suitable
candidate for an integrability condition.Comment: 13 pages,uses LATeX2e and epsf. File prepared using the uufiles
packag
Crossing Symmetry Violation of Unitarized Pion-Pion Amplitude in the Resonance Region
Pion-pion scattering amplitude obtained from one-loop Chiral Perturbation
Theory (ChPT) is crossing symmetric, however the corresponding partial wave
amplitudes do not respect exact unitarity relation. There are different
approaches to get unitarized partial wave amplitudes from ChPT. Here we
consider the inverse amplitude method (IAM) that is often used to fit pion-pion
phase shifts to experimental data, by adjusting free parameters. We measure the
amount of crossing symmetry violation (CSV) in this case and we show that
crossing symmetry is badly violated by the IAM unitarized ChPT amplitude in the
resonance region. Important CSV also occurs when all free parameters are set
equal to zero.Comment: 6 pages, 4 figure
Fast transform decoding of nonsystematic Reed-Solomon codes
A Reed-Solomon (RS) code is considered to be a special case of a redundant residue polynomial (RRP) code, and a fast transform decoding algorithm to correct both errors and erasures is presented. This decoding scheme is an improvement of the decoding algorithm for the RRP code suggested by Shiozaki and Nishida, and can be realized readily on very large scale integration chips
Synthesis of a Novel Pyrrole Family as Potential Anti-Cancer Agents
A one-step selective reaction was developed to synthesize a novel pyrrole family (20 different members) from a keto-epoxide and several aromatic amines at room temperature in 3h. When substituting aromatic amine with aliphatic amines or inorganic bases, furan derivatives were produced selectively. The kinetic behavior of the reactions and structure of the products were characterized by nuclear magnetic resonance spectroscopy. The results showed that our reaction is selective with high yields (\u3e 85%). To understand the selective formation of pyrrole and furan, we conducted computational experiences to study the mechanisms of the primary reaction and its competitor using Density Functional Theory with B3LYP methods and LACVP basis set. Our main contribution was to develop a simple yet selective reaction to synthesize pyrrole derivatives with a strong potential for pharmaceutical application
Gender, poverty and social justice
Views on poverty are deeply rooted in cultural frameworks about the human condition shaped by histories. In the debate on modernity, perspec
Heun Functions and the energy spectrum of a charged particle on a sphere under magnetic field and Coulomb force
We study the competitive action of magnetic field, Coulomb repulsion and
space curvature on the motion of a charged particle. The three types of
interaction are characterized by three basic lengths: l_{B} the magnetic
length, l_{0} the Bohr radius and R the radius of the sphere. The energy
spectrum of the particle is found by solving a Schr\"odinger equation of the
Heun type, using the technique of continued fractions. It displays a rich set
of functioning regimes where ratios \frac{R}{l_{B}} and \frac{R}{l_{0}} take
definite values.Comment: 12 pages, 5 figures, accepted to JOPA, november 200
Complete control of a matter qubit using a single picosecond laser pulse
We demonstrate for the first time that a matter physical two level system, a
qubit, can be fully controlled using one ultrafast step. We show that the spin
state of an optically excited electron, an exciton, confined in a quantum dot,
can be rotated by any desired angle, about any desired axis, during such a
step. For this we use a single, resonantly tuned, picosecond long, polarized
optical pulse. The polarization of the pulse defines the rotation axis, while
the pulse detuning from a non-degenerate absorption resonance, defines the
magnitude of the rotation angle. We thereby achieve a high fidelity, universal
gate operation, applicable to other spin systems, using only one short optical
pulse. The operation duration equals the pulse temporal width, orders of
magnitude shorter than the qubit evolution life and coherence times.Comment: main text: 4 pages, 3 figures Supplemental material: 3 pages, 1
figur
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