413 research outputs found
Relativistic J-matrix method
The relativistic version of the J-matrix method for a scattering problem on
the potential vanishing faster than the Coulomb one is formulated. As in the
non-relativistic case it leads to a finite algebraic eigenvalue problem. The
derived expression for the tangent of phase shift is simply related to the
non-relativistic case formula and gives the latter as a limit case. It is due
to the fact that the used basis set satisfies the ``kinetic balance
condition''.Comment: 21 pages, RevTeX, accepted for publication in Phys. Rev.
Density of States Extracted from Modified Recursion Relations
We evaluate the density of states (DOS) associated with tridiagonal symmetric
Hamiltonian matrices and study the effect of perturbation on one of its
entries. Analysis is carried out by studying the resulting three-term recursion
relation and the corresponding orthogonal polynomials of the first and second
kind. We found closed form expressions for the new DOS in terms of the original
one when perturbation affects a single diagonal or off-diagonal site or a
combination of both. The projected DOS is also calculated numerically and its
relation to the average DOS is explored both analytically and numerically.Comment: 15 pages including 8 figures (one in color
Singular Short Range Potentials in the J-Matrix Approach
We use the tools of the J-matrix method to evaluate the S-matrix and then
deduce the bound and resonance states energies for singular screened Coulomb
potentials, both analytic and piecewise differentiable. The J-matrix approach
allows us to absorb the 1/r singularity of the potential in the reference
Hamiltonian, which is then handled analytically. The calculation is performed
using an infinite square integrable basis that supports a tridiagonal matrix
representation for the reference Hamiltonian. The remaining part of the
potential, which is bound and regular everywhere, is treated by an efficient
numerical scheme in a suitable basis using Gauss quadrature approximation. To
exhibit the power of our approach we have considered the most delicate region
close to the bound-unbound transition and compared our results favorably with
available numerical data.Comment: 14 pages, 5 tables, 2 figure
Quantum Spin Excitations through the metal-to-insulator crossover in
We use inelastic neutron scattering to study the temperature dependence of
the spin excitations of a detwinned superconducting YBaCuO
( K). In contrast to earlier work on YBaCuO (
K), where the prominent features in the magnetic spectra consist of a sharp
collective magnetic excitation termed ``resonance'' and a large
( meV) superconducting spin gap, we find that the spin
excitations in YBaCuO are gapless and have a much broader
resonance. Our detailed mapping of magnetic scattering along the
/-axis directions at different energies reveals that spin
excitations are unisotropic and consistent with the ``hourglass''-like
dispersion along the -axis direction near the resonance, but they are
isotropic at lower energies. Since a fundamental change in the low-temperature
normal state of YBaCuO when superconductivity is suppressed
takes place at with a metal-to-insulator crossover (MIC), where the
ground state transforms from a metallic to an insulating-like phase, our
results suggest a clear connection between the large change in spin excitations
and the MIC. The resonance therefore is a fundamental feature of metallic
ground state superconductors and a consequence of high- superconductivity.Comment: 9 pages, 7 figures, accepted by Phys. Rev.
Incommensurate Spin Ordering and Fluctuations in underdoped La_{2-x}Ba_{x}CuO_{4}
Using neutron scattering techniques, we have studied incommensurate spin
ordering as well as low energy spin dynamics in single crystal underdoped \LBCO
with x0.095 and 0.08; high temperature superconductors with T 27
K and 29 K respectively. Static two dimensional incommensurate magnetic order
appears below T=39.5 0.3 K in \LBCO (x=0.095) and a similar
temperature for x=0.08 within the low temperature tetragonal phase. The spin
order is unaffected by either the onset of superconductivity or the application
of magnetic fields of up to 7 Tesla applied along the c-axis in the x=0.095
sample. Such magnetic field {\it independent} behaviour is in marked contrast
with the field induced enhancement of the staggered magnetisation observed in
the related \LSCO system, indicating this phenomenon is not a universal
property of cuprate superconductors. Surprisingly, we find that
incommensurability is only weakly dependent on doping relative to
\LSCO. Dispersive excitations in \LBCO (x=0.095) at the same incommensurate
wavevector persist up to at least 60 K. The dynamical spin susceptibility of
the low energy spin excitations saturates below \tc, in a similar manner to
that seen in the superconducting state of LaCuO.Comment: 9 pages, 7 figures, submitted to PRB, figures update
Efisiensi Pemasaran Jagung di Kelurahan Kalampangan Kecamatan Sabangau Kota Palangka Raya
The aim of this research is to analyze marketing channel, marketing institution, marketing function, marketing margin, marketing cost, marketing profit, corn farmer's share, marketing efficiency of maize in various channel in Kalampangan village. The results showed that: (1) marketing of corn in Kalampangan village there are two kinds of channels, where channel I involves four institutions namely: farmers, merchants village, retailers, and consumers. While channel II involves two institutions only, namely, farmers as traders and consumers. Maize's marketing functions are: sales function, purchasing function, storage function, transport function and facility function. (2) From calcution result at Marketing Channel I, total marketing margin of maize in Kalampangan Villge is Rp. 3.860,-/kg, total cost of corn marketing is Rp. 310,-/kg, total profit of corn marketing is Rp. 3.550,-/kg and the result obtained by corn farmer are 58,04%. From calculating result at Marketing Channel II, total margin of maize in Kalampangan Village is Rp. 2.160,-/kg, total cost of corn marketing is Rp. 310,-/kg, total profit of corn marketing is Rp. 1.850,-/kg and the result obtained by corn farmer are 71,20%. (3) marketing efficiency at Marketing Channel I equal to 41.96%, and on Marketing Channel II is 28,80%. Marketing efficiency value in Channel I is lower than marketing efficiency II, it is considered more efficient marketing Channel II
Scattering theory with a natural regularization: Rediscovering the J-matrix method
In three dimensional scattering, the energy continuum wavefunction is
obtained by utilizing two independent solutions of the reference wave equation.
One of them is typically singular (usually, near the origin of configuration
space). Both are asymptotically regular and sinusoidal with a phase difference
(shift) that contains information about the scattering potential. Therefore,
both solutions are essential for scattering calculations. Various
regularization techniques were developed to handle the singular solution
leading to different well-established scattering methods. To simplify the
calculation the regularized solutions are usually constructed in a space that
diagonalizes the reference Hamiltonian. In this work, we start by proposing
solutions that are already regular. We write them as infinite series of square
integrable basis functions that are compatible with the domain of the reference
Hamiltonian. However, we relax the diagonal constraint on the representation by
requiring that the basis supports an infinite tridiagonal matrix representation
of the wave operator. The hope is that by relaxing this constraint on the
solution space a larger freedom is achieved in regularization such that a
natural choice emerges as a result. We find that one of the resulting two
independent wavefunctions is, in fact, the regular solution of the reference
problem. The other is uniquely regularized in the sense that it solves the
reference wave equation only outside a dense region covering the singularity in
configuration space. However, asymptotically it is identical to the irregular
solution. We show that this natural and special regularization is equivalent to
that already used in the J-matrix method of scattering.Comment: 10 page
Exercise intolerance in chronic heart failure is not associated with impaired recovery of muscle function or submaximal exercise performance
Objectives.This study investigated whether recovery of skeletal muscle function is impaired in patients with heart failure and whether impaired recovery is associated with abnormal submaximal systemic exercise tolerance during repeated testing.Background.Patients with heart failure experience fatigue during daily activities. Because abnormalities of skeletal muscle play a role in their exercise intolerance, these symptoms may reflect a delay in muscle recovery and a resulting limitation in submaximal exercise tolerance.Methods.Two protocols were used. In protocol 1, knee extensor strength and endurance, and their recovery after fatiguing exercise, were evaluated in 11 patients (mean [±SEM] age 62 ± 5 years, New York Heart Association functional class 2.3 ± 0.2, ejection fraction 24 ± 5%) and in 10 age-matched sedentary control subjects. Protocol 2 examined the recovery of knee extensor endurance and submaximal exercise tolerance, as quantified on a self-powered treadmill, over 24 h in 18 patients (mean age 65 ± 3 years, functional class 2.4 ± 0.2, ejection fraction 23 ± 3%) and in 10 control subjects.Results.Peak oxygen consumption was reduced in both heart failure groups (15.4 ± 1.4 and 15.6 ± 1.0 ml/kg per min) compared with that in the respective control groups (23.1 ± 2.9 and 25.6 ± 1.0 ml/kg per min, both p < 0.05), as was muscle endurance but not muscle strength. In protocol 1, knee extensor endurance recovered more slowly in the patients than in control subjects (to 62 ± 4% and 87 ± 7% of the baseline value after 5 min, respectively, p < 0.05). In protocol 2, submaximal exercise tolerance was lower in the patients with heart failure than in control subjects (1,075 ± 116 vs. 1,390 ± 110 m), but knee extensor endurance and walking distance recovered fully by 10 and 30 min, respectively.Conclusions.Although these findings confirm earlier studies that demonstrated impaired muscle endurance in patients with heart failure, the results provide no evidence that recovery of either muscle function or submaximal exercise tolerance is delayed beyond the initial 5 to 10 min after exercise
Analysis of the role neotectonic and sedimentation in bed changes of Jagin River
Jagin River with the formation of a relatively large delta arrive to the Oman Sea. In this paper rely on results based on field survey and index of geomorphic, has been studied morphology and riverbed changes. The purpose of this study is recognition impact of neotectonic in jagin river drainage network. Morphology and behaviour of drainage network, to change from neotectonic is sensitive. Considering the evidence as changes multiple paths in different time periods, crossing the fault line, broad and narrow riverbed, it seems that under the influence of neotectonic active in the region. For achieving results, Geodynamic data, Index geomorphic, Time of Concentration, topographic and geologic maps, aerial photos and satellite images of this area as the main reaserch tools and conceptual and model techniques were used. Then the data through field works by GIS (ArcGIS&ilwis) analysis and effect of tectonic analysed. In this view, between redirected drainage and morphological feature and neotectonic affects has been relationship. Results indicate continuity of the last neotectonic activity in the Study area and displacement Amount of activity is not the same everywhere, and movement is towards the north eastern region. The findings of this research can be useful for the study of impact of neotectonic on riverbed changes
J-matrix method of scattering in one dimension: The nonrelativistic theory
We formulate a theory of nonrelativistic scattering in one dimension based on
the J-matrix method. The scattering potential is assumed to have a finite range
such that it is well represented by its matrix elements in a finite subset of a
basis that supports a tridiagonal matrix representation for the reference wave
operator. Contrary to our expectation, the 1D formulation reveals a rich and
highly non-trivial structure compared to the 3D formulation. Examples are given
to demonstrate the utility and accuracy of the method. It is hoped that this
formulation constitutes a viable alternative to the classical treatment of 1D
scattering problem and that it will help unveil new and interesting
applications.Comment: 24 pages, 9 figures (3 in color
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