Zero-temperature Phase Diagram of Two Dimensional Hubbard Model

We investigate the two-dimensional Hubbard model on the triangular lattice with anisotropic hopping integrals at half filling. By means of a self-energy functional approach, we discuss how stable the non-magnetic state is against magnetically ordered states in the system. We present the zero-temperature phase diagram, where the normal metallic state competes with magnetically ordered states with $(\pi, \pi)$ and $(2\pi/3, 2\pi/3)$ structures. It is shown that a non-magnetic Mott insulating state is not realized as the ground state, in the present framework, but as a meta-stable state near the magnetically ordered phase with $(2\pi/3, 2\pi/3)$ structure.Comment: 4 pages, 4 figure

Phytohaemagglutinin on maternal and umbilical leukocytes

Almost all the umbilical lymphocytes showed more extensive blast cell formation than that of their mother's lymphocytes with PHA. Pathological conditions of mother in pregnancy and labor such as anemia, gestational toxicosis, difficult labor and asphyxia of babies, inhibited the normal response of both maternal and umbilical lymphocytes to PHA.</p

Current-feedback-stabilized laser system for quantum simulation experiments using Yb clock transition at 578 nm

We developed a laser system for the spectroscopy of the clock transition in ytterbium (Yb) atoms at 578 nm based on an interference-filter stabilized external-cavity diode laser (IFDL) emitting at 1156 nm. Owing to the improved frequency-to-current response of the laser-diode chip and the less sensitivity of the IFDL to mechanical perturbations, we succeeded in stabilizing the frequency to a high-finesse ultra-low-expansion glass cavity with a simple current feedback system. Using this laser system, we performed high-resolution clock spectroscopy of Yb and found that the linewidth of the stabilized laser was less than 320 Hz.Comment: 5 pages, 7 figure

Farm Machinery Hire Services For Small Farms In Kampar Regency, Riau Province, Indonesia

Small farmers in the Kampar Regency are dependent on farm machinery hire services for their farm operations. This study aims to provide an understanding of the management procedures of hire services groups and to determine the seasonal working areas and custom rates of machinery hire services managed by farmer groups. Twenty groups offering custom hiring services in seven districts of the Kampar Regency were visited during the rainy season in 2012, and group managers, mechanics, and operators were interviewed to collect field data. The results showed that these groups comprised 3-11 farmer groups, which in turn comprised 15-25 farm owners each. Each group had a simple organizational structure and managed one or more farm machines of various manufacturers and types. The number of machines owned by each group was not sufficient to deploy across the entire coverage area owned by the group members. The seasonal working area is small due to the limited number of machines owned, short working days per season, small paddy field areas, and low working capacities. The custom rates varied across groups depending on the type of machine and operation, land conditions, and the distance between the field and the hire services center. Suggestions for improving the operational performance of hire services groups have been proposed

Economic potential of tractor hire business in Riau Province, Indonesia: A case study of small tractors for small rice farms

This study attempts to evaluate the potential of hand tractor hire business to increase the owners’income. The type of small tractors studied is used to promote the small rice farms’mechanization. A survey of 56 tractor owners in four regencies of Riau Province was conducted to carry out this evaluation. Approximately 68% of the total annual costs are variable costs and the largest single item is labor cost. Most tractors offering custom hire service are profitable with an average of 23.13 ha per annum. The received profit would be higher if drivers are provided by the owners. The breakeven point that justifies economical ownership of the small tractors is at 17.35 ha under Riau conditions. The owners require 6.5 years to retrieve the capital cost on the tractors and to obtain about 10% of return on the investment. The annual use of tractors should be increased to reduce costs or to augment profit. The use of tractors for customer hire service should be encouraged for augmenting farmers’income and enhancing tractor ownership in the province

Economic potential of tractor hire business in Riau Province, Indonesia: A case study of small tractors for small rice farms

This study attempts to evaluate the potential of hand tractor hire business to increase the owners&rsquo; income. &nbsp;The type of small tractors studied is used to promote the small rice farms&rsquo; mechanization. &nbsp;A survey of 56 tractor owners in four regencies of Riau Province was conducted to carry out this evaluation. &nbsp;Approximately 68% of the total annual costs are variable costs and the largest single item is labor cost. &nbsp;Most tractors offering custom hire service are profitable with an average of 23.13 ha per annum. &nbsp;The received profit would be higher if drivers are provided by the owners. &nbsp;The breakeven point that justifies economical ownership of the small tractors is at 17.35 ha under Riau conditions.&nbsp; The owners require 6.5 years to retrieve the capital cost on the tractors and to obtain about 10% of return on the investment. &nbsp;The annual use of tractors should be increased to reduce costs or to augment profit. &nbsp;The use of tractors for customer hire service should be encouraged for augmenting farmers&rsquo; income and enhancing tractor ownership in the province.Keywords: tractor hire business, small tractor, annual use, tractor costs, breakeven point&nbsp;Citation: Paman, U., S. Uchida, and S. Inaba. &nbsp;Economic potential of tractor hire business in Riau Province, Indonesia: A case study of small tractors for small rice farms. &nbsp;Agric Eng Int: CIGR Journal, 2010, 12(1): 135-142

Shock propagation through a bubbly liquid in a deformable tube

Shock propagation through a bubbly liquid contained in a deformable tube is considered. Quasi-one-dimensional mixture-averaged flow equations that include fluid–structure interaction are formulated. The steady shock relations are derived and the nonlinear effect due to the gas-phase compressibility is examined. Experiments are conducted in which a free-falling steel projectile impacts the top of an air/water mixture in a polycarbonate tube, and stress waves in the tube material and pressure on the tube wall are measured. The experimental data indicate that the linear theory is incapable of properly predicting the propagation speeds of finite-amplitude waves in a mixture-filled tube; the shock theory is found to more accurately estimate the measured wave speeds

Factors Affecting Repair Costs of Small Tractor Use in Riau Province, Indonesia

Factors affecting annual repair costs were analyzed and a reasonable function was proposed by including more explanatory variables than the previous models for small tractors. Data used in this study was based on a survey of 62 tractors from three selected regencies in Riau Province in 2003. As a result, tractor age, usage, horsepower and operator skill were statistically significant explanatory variables, whereas the ownership system and manufacturer weren’t. Using the proposed model, the annual repair costs were estimated to increase during the expected life of tractors. Changes in usage, horsepower, and operator skill increased more rapidly for annual and cumulative repair costs over the tractor lifespan. Of the significant variables, the effect is more pronounced for operator skill variable. The results suggest that priority should be given to operator training and selection