3,602 research outputs found
A direct calculation of critical exponents of two-dimensional anisotropic Ising model
Using an exact solution of the one-dimensional (1D) quantum transverse-field
Ising model (TFIM), we calculate the critical exponents of the two-dimensional
(2D) anisotropic classical Ising model (IM). We verify that the exponents are
the same as those of isotropic classical IM. Our approach provides an
alternative means of obtaining and verifying these well-known results.Comment: 3 pages, no figures, accepted by Commun. Theor. Phys.(IPCAS
The Effect of Different Irrigation Regimes on the Yield of Fodder Maize (Zea Mays)
A field study was carried out during 2013 season to investigate the effect of different irrigation intervals on fodder maize yield. Randomized complete block design (RCBD) was used, with three replicates. . Four irrigation regimes were executed T1=3 irrigations (1st 20 Day After Sowing (DAS), 2nd 35 DAS and 3rd 50 DAS), T2=3 irrigations (1st 20 DAS, 2nd 40 DAS and 3rd 60 DAS), T3=3 irrigations (1st 25 DAS, 2nd 40 DAS and 3rd 55 DAS), and T4=3 irrigations (1st 30 DAS, 2nd 45 DAS and 3rd 60 DAS). The results indicated that fodder maize yield varied significantly (P<0.05) under different irrigation regimes. The treatment T1 resulted the best, plant height (185.33 cm), number of green leaves (13.42), stem width (4.46 cm), and fodder yield (30580 kg.ha-1) While T2 resulted in the best Seed germination (86.91%). Finally, T1 irrigation regime was most effective to produce higher fodder yield in maize and the farmers may adopt this treatment to get high fodder production from maize. Keywords: Fodder maize, Yield, Irrigation regime
Synthesis and Magnetic Properties of Cobalt Ferrite (CoFe2O4) Nanoparticles Prepared by Wet Chemical Route
Magnetic nanoparticles of cobalt ferrite have been synthesized by wet
chemical method using stable ferric and cobalt salts with oleic acid as the
surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM)
confirmed the formation of single phase cobalt ferrite nanoparticles in the
range 15-48nm depending on the annealing temperature and time. The size of the
particles increases with annealing temperature and time while the coercivity
goes through a maximum, peaking at around 28nm. A very large coercivity
(10.5kOe) is observed on cooling down to 77K while typical blocking effects are
observed below about 260K. The high field moment is observed to be small for
smaller particles and approaches the bulk value for large particles.Comment: 18 pages, accepted in JMMM, (May, 2006
Three-Body Forces Produced by a Similarity Renormalization Group Transformation in a Simple Model
A simple class of unitary renormalization group transformations that force
hamiltonians towards a band-diagonal form produce few-body interactions in
which low- and high-energy states are decoupled, which can greatly simplify
many-body calculations. One such transformation has been applied to
phenomenological and effective field theory nucleon-nucleon interactions with
success, but further progress requires consistent treatment of at least the
three-nucleon interaction. In this paper we demonstrate in an extremely simple
model how these renormalization group transformations consistently evolve two-
and three-body interactions towards band-diagonal form, and introduce a
diagrammatic approach that generalizes to the realistic nuclear problem.Comment: 25 pages, 18 figures, minor typos corrected and references update
Assessing the damming effects on runoff using a multiple linear regression model: A case study of the Manwan Dam on the Lancang River
AbstractThe Lancang River in Yunnan Province, with a length of 1170km and a 1780-m drop from northwest to southeast, is the most controversial river in southwest China because 14 cascade hydropower stations have been planned on the main waterway. The Manwan Dam, the first of the 14 dams, began operating in 1993, and the associated downstream runoff may have been affected by its construction. To assess this impact, we first investigated the relationships between monthly runoff observed from the Gajiu station and meteorological data obtained from four meteorological gauging stations with a time-lag of 0-3 months over the pre-dam period (1957-2000). Second, we established and validated a multiple linear regression equation employing monthly meteorological and hydrological data during the pre-dam period. Finally, we simulated the monthly runoff after dam construction (1993-2000) using the established equations and assessed the impact of dam construction on runoff by comparing the observed actual monthly runoff with the simulated monthly runoff. Our results suggested a very high hydro-meteorological correlation for the pre-dam period, which opened up the possibility of runoff forecasting. Further, the multiple linear regression equation displayed good simulation performance as coefficient of determination (R2) and the Nash-Suttcliffe coefficient (NS) reached 0.84 and 0.82 respectively. By comparing the observed and the predicted monthly runoff, we found that construction of the Manwan Dam caused a visible disturbance on monthly runoff that, with the disturbance value, displayed a multi-peak fluctuation of up-down variation in the annual hydrologic regime circl
Elementary excitations in one-dimensional spin-orbital models: neutral and charged solitons and their bound states
We study, both numerically and variationally, the interplay between different
types of elementary excitations in the model of a spin chain with anisotropic
spin-orbit coupling, in the vicinity of the "dimer line" with an exactly known
dimerized ground state. Our variational treatment is found to be in a
qualitative agreement with the exact diagonalization results. Soliton pairs are
shown to be the lowest excitations only in a very narrow region of the phase
diagram near the dimer line, and the phase transitions are always governed by
magnon-type excitations which can be viewed as soliton-antisoliton bound
states. It is shown that when the anisotropy exceeds certain critical value, a
new phase boundary appears. In the doped model on the dimer line, the exact
elementary charge excitation is shown to be a hole bound to a soliton. Bound
states of those "charged solitons" are studied; exact solutions for N-hole
bound states are presented.Comment: 11 pages revtex, 6 figure
Diffuse neutron reflectivity and AFM study of interface morphology of an electro-deposited Ni/Cu film
We present a detailed study of the interface morphology of an
electro-deposited (ED) Ni/Cu bilayer film by using off-specular (diffuse)
neutron reflectivity technique and Atomic Force Microscopy (AFM). The Ni/Cu
bilayer has been electro-deposited on seed layers of Ti/Cu. These two seed
layers were deposited by magnetron sputtering. The depth profile of density in
the sample has been obtained from specular neutron reflectivity data. AFM image
of the air-film interface shows that the surface is covered by globular islands
of different sizes. The AFM height distribution of the surface clearly shows
two peaks [Fig. 3] and the relief structure (islands) on the surface in the
film can be treated as a quasi-two-level random rough surface structure. We
have demonstrated that the detailed morphology of air-film interfaces, the
quasi-two level surface structure as well as morphology of the buried
interfaces can be obtained from off-specular neutron reflectivity data. We have
shown from AFM and off-specular neutron reflectivity data that the morphologies
of electro-deposited surface is distinctly different from that of
sputter-deposited interface in this sample. To the best of our knowledge this
is the first attempt to microscopically quantify the differences in
morphologies of metallic interfaces deposited by two different techniques viz.
electro-deposition and sputtering
Griffiths Effects in Random Heisenberg Antiferromagnetic S=1 Chains
I consider the effects of enforced dimerization on random Heisenberg
antiferromagnetic S=1 chains. I argue for the existence of novel Griffiths
phases characterized by {\em two independent dynamical exponents} that vary
continuously in these phases; one of the exponents controls the density of
spin-1/2 degrees of freedom in the low-energy effective Hamiltonian, while the
other controls the corresponding density of spin-1 degrees of freedom.
Moreover, in one of these Griffiths phases, the system has very different low
temperature behavior in two different parts of the phase which are separated
from each other by a sharply defined crossover line; on one side of this
crossover line, the system `looks' like a S=1 chain at low energies, while on
the other side, it is best thought of as a chain. A strong-disorder RG
analysis makes it possible to analytically obtain detailed information about
the low temperature behavior of physical observables such as the susceptibility
and the specific heat, as well as identify an experimentally accessible
signature of this novel crossover.Comment: 16 pages, two-column PRB format; 5 figure
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