Spin-Charge Decoupling and Orthofermi Quantum Statistics

Currently Gutzwiller projection technique and nested Bethe ansatz are two main methods used to handle electronic systems in the $U$ infinity limit. We demonstrate that these two approaches describe two distinct physical systems. In the nested Bethe ansatz solutions, there is a decoupling between the spin and charge degrees of freedom. Such a decoupling is absent in the Gutzwiller projection technique. Whereas in the Gutzwiller approach, the usual antisymmetry of space and spin coordinates is maintained, we show that the Bethe ansatz wave function is compatible with a new form of quantum statistics, viz., orthofermi statistics. In this statistics, the wave function is antisymmetric in spatial coordinates alone. This feature ultimately leads to spin-charge decoupling.Comment: 12 pages, LaTex Journal_ref: A slightly abridged version of this paper has appeared as a brief report in Phys. Rev. B, Vol. 63, 132405 (2001

Assessing Participation in the Milk Income Loss Contract Program and its Impact on Milk Production

The MILC program, a counter-cyclical income support program, was designed to provide price support to dairy farmers. Since the inception of the MILC program it has been argued that the program is inefficient and rewards inefficiency by keeping high cost, small dairy farms in business. Large dairy producers have expressed concerns that the MILC payments have negatively affected their farming income. Using farm-level, ARMS data from 2005, this study investigated the factors that affect farmer’s decision to participate in MILC program and if participation in MILC has an impact on milk production. The results show that participation in MILC program is positively correlated with farmer’s educational attainment, organic certification subsidy, milk price, off-farm work by spouses, and financial record keeping. Further, medium sized dairy farms are more likely to participate in MILC program. Finally, results indicate that participation in MILC program has a positive impact on milk production.dairy farms, agricultural policy, Milk Income Loss Contract Program, two-step probit estimation, Agricultural and Food Policy, Livestock Production/Industries, H20, Q13, Q18,

Size-dependent magnetization fluctuations in NiO nanoparticles

The finite size and surface roughness effects on the magnetization of NiO nanoparticles is investigated. A large magnetic moment arises for an antiferromagnetic nanoparticle due to these effects. The magnetic moment without the surface roughness has a non-monotonic and oscillatory dependence on $R$, the size of the particles, with the amplitude of the fluctuations varying linearly with $R$. The geometry of the particle also matters a lot in the calculation of the net magnetic moment. An oblate spheroid shape particle shows an increase in net magnetic moment by increasing oblateness of the particle. However, the magnetic moment values thus calculated are very small compared to the experimental values for various sizes, indicating that the bulk antiferromagnetic structure may not hold near the surface. We incorporate the surface roughness in two different ways; an ordered surface with surface spins inside a surface roughness shell aligned due to an internal field, and a disordered surface with randomly oriented spins inside surface roughness shell. Taking a variational approach we find that the core interaction strength is modified for nontrivial values of $\Delta$ which is a signature of multi-sublattice ordering for nanoparticles. The surface roughness scale $\Delta$ is also showing size dependent fluctuations, with an envelope decay $\Delta\sim R^{-1/5}$. The net magnetic moment values calculated using spheroidal shape and ordered surface are close to the experimental values for different sizes.Comment: 19 pages, 8 figures, Accepted for publication in Int. J. Mod. Phys.