Cosmological Constant and Gravitational Repulsion Effect: 1. Homogeneous models with radiation

Within the framework of the minimum quadratic Poincare gauge theory of gravity in the Riemann-Cartan spacetime we study the influence of gravitational vacuum energy density (a cosmological constant) on the dynamics of various gravitating systems. It is shown that the inclusion of the cosmological term can lead to gravitational repulsion. For some simple cases of spatially homogeneous cosmological models with radiation we obtain non-singular solutions in form of elementary functions and elliptic integrals.Comment: REVTEX, 11 pages, Syracuse University preprint SU-GP-93/5-

Influences Of Lime And Coconut Fiber To Arsenic Uptake On Peanuts In An Phu District, An Giang Province

Arsenic (As) contamination in deep-well water has presently been warned in some areas of An Giang province. The previous studies in An Phu district showed that the level of As in soils was also many folds higher than international standards that need to be studied; particularly in land use and water supply in agricultural production. The objectives of this research were to: (i) evaluate the situation of As contain in soil and well water from cultivated lands in An Phu district, An Giang province; (ii) evaluate the impact of coconut fiber and liming methods on the uptake and accumulation of As in peanuts. The survey studies indicated that all of deep-well water samples were contaminated with As from 97,5 μg/l to 469 μg/l in An Phu district. These levels exceed Vietnamese and WHO standards (<10 μg/L), and all studied communes used deep-well water for watering their crops (69,6%). The As averages of soil samples inside dikes were higher than outside dikes from 1,5 to 2 times. As concentration of all soil samples for planting peanuts inside the dike are always higher than outside the dike from 1,5 to 2 times. The averages of As levels of arable land samples inside dikes of An Phu district were from 40,1 to 47,8 mg/kg. When applied 5 tons of lime and coconut fiber per ha reduced As levels at 55,3% compared with treatment without lime and coconut fiber. The results also showed that, when applied lime 5 tons of lime and coconut fiber per ha had a significant effect on the growth and yield of peanuts. Productivity of the peanut that increased from 9,10% to 30,4%, compared without liming and coconut fiber. When applied lime, coconut fiber had a significant effect on amount of As in grains and bodies of peanuts was lower than without lime and coconut fiber treatments.The yield components indicated, peanuts were planted with coconut fiber and l liming, that had the best result and the the lowest was without liming and coconut fiber. When applied 5 tons of liming combined with coconut fiber per ha had the highest results, both level of As reduction in peanut grains and productivity. Necessary to study many levels of liming and coconut fiber and residual lime in the soil for the next crops. It recommend that people have safe farming methods and effects on soils of as contamination

Rice cultivation and soil properties as affected by Alternative Wetting and Drying irrigation in Chau Thanh, An Giang province

The study that was carried out in winter-spring 2018 in Thoai Son, An Giang province, include experiments: Effects of (AWDI) to (i) Characters in soil; (ii) rice yield and (iii) water use and water use efficiency of Jasmine rice. The experiment was carried out with 4 treatments, 4 replications. The treatments ranged from continuous submergence (NT1) of the field to a number of delayed irrigations (NT2, NT3, NT4) denoting application of 4 cm irrigation water when water level in the perforated PVC pipe fell 18, 14 and 10 cm below ground level. The study revealed that NT1 attributed by the highest total water use (118 cm) and the lowest WUE (60.3 kg/ha/cm) produced the highest grain yield (8,10 t/ha). On the contrary, the yields in NT3 (6.80 t/ha) and NT2 (5.80 t/ha) were significantly lower at 0,5 times level of significance compared to that of NT1 and NT4 (7.83 t/ha)