39 research outputs found
Counterterm Method in Lovelock Theory and Horizonless Solutions in Dimensionally Continued Gravity
In this paper we, first, generalize the quasilocal definition of the stress
energy tensor of Einstein gravity to the case of Lovelock gravity, by
introducing the tensorial form of surface terms that make the action
well-defined. We also introduce the boundary counterterm that removes the
divergences of the action and the conserved quantities of the solutions of
Lovelock gravity with flat boundary at constant and . Second, we obtain
the metric of spacetimes generated by brane sources in dimensionally continued
gravity through the use of Hamiltonian formalism, and show that these solutions
have no curvature singularity and no horizons, but have conic singularity. We
show that these asymptotically AdS spacetimes which contain two fundamental
constants are complete. Finally we compute the conserved quantities of these
solutions through the use of the counterterm method introduced in the first
part of the paper.Comment: 15 pages, references added, typos correcte
Acid-modified Biochar Effect on Some Physiological Indicators and Micronutrient Availability of Quinoa (cv. Gizavan) in a Calcareous Soil
Introduction
Organic matter and alkaline pH are the main causes of nutrient deficiencies in calcareous soils of arid and semi-arid regions. The availability of some nutritional elements, including the micronutrients such as iron, zinc, copper, and manganese is very low in calcareous soils, although the total concentration of these elements may be relatively high. Burning crop residues results in substantial loss of nutrients, and may lead to air pollution and human health problems. An alternative approach is to apply crop residues to soil in the form of biochar. The biochar modification with acid may increase the solubility of nutrients (P, Fe, Zn, Cu, Mn) present in biochar, thereby significant improvement in mineral nutrition of plants grown in calcareous soils. Therefore, the object of this study is to investigate the effect of acid-modified biochar from rice residues on the amount of chlorophyll and the micronutrient concentration of quinoa plant (Chenopodium quinoa) in a calcareous soil.
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Methods and Materials
The soil was air-dried and ground to pass through a 2-mm sieve then was analyzed to determine various soil physico-chemical properties using standard methods. To achieve the aim of this study the factorial experiment was carried out based on a completely randomized design in 4 replications. Factors include 3 types of biochar (unmodified, modified by pre-acidic method and modified by post-acidic method) and different levels of biochar (0, 2, and 5% by weight). Then 10 quinoa seeds were planted in each pot at 2-cm depth which after emergence, declined to 3 plants in each pot. The pots were randomly moved twice a week during the growth period to eliminate environmental effects. Irrigation and weeding operations were performed by hand. Determination of chlorophyll content (a, b, and ab) and carotenoids were measured precisely before harvesting in fresh plants using Arnon method. Plants were harvested at 187 days after planting, washed with distilled water and dry with tissue paper. The samples were air-dried and then oven dried at 65˚C to a constant weight in a forced air-driven oven. Then the total micronutrient content of the plant was determined after dry ashing. The statistical results of the data were analyzed using SAS software (9.4) and LSD test (at 5% level) was used for comparing the mean values.
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Results and Discussion
Based on the variance analysis, all attributes responded positively to different types and levels of biochar and modified biochar (p<0.01). The comparison of the average effect of the studied treatments showed that with the increase in the levels of all three types of biochar, the amount of chlorophyll a, b, total, and carotenoid increased so the highest amount of chlorophyll a, b, total, and carotenoid respectively, with an average of 2.58 and 1.54, 4.13 and 1.36 mg g-1 were obtained from the treatment of 5% post-acidic biochar. The results showed that the highest amount of Fe concentration in shoots with an average of 229.48 mg kg-1 was obtained from the treatment of 5% post-acidic biochar, although there was no statistically significant difference with the treatment of 5% pre-acidic biochar with an average of 220.48 mg kg-1 and its lowest value with an average of 95.95 mg kg-1 was related to unmodified biochar. The highest amount of Zn concentration in shoots with an average of 13.42 mg kg-1 was related to the treatment of 5% post-acidic biochar which showed an increase of 13.24 and 33.26% compared to the treatment of 5% pre-acidic and unmodified biochar, respectively. Also, the highest concentrations of Cu and Mn in shoots were obtained with an average of 3.85 and 23.37 mg kg-1 respectively, from the treatment of 5% post-acidic biochar.
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Conclusion
Post-acidic biochar had better results in terms of physiological indices and the concentration of micronutrients (Fe, Zn, Cu, and Mn) than unmodified biochar in quinoa. The increase of nutrients in quinoa can be attributed to the dissolution of biochar nutrients after being modified with acid and the reduction of pH and the availability of these elements in the soil. Therefore, biochar modified with acid or biochar produced from sources that have acidic properties can be recommended as a suitable method for improving fertility and increasing micronutrients in calcareous soils affected by salt
Comparison of Acupressure Effect on Sanyinjiao Point with that of Vitamin E on Primary Dysmenorrhea
Introduction & Objective: Dysmenorrhea is a common gynecologic disorder which at least fifty percent of women experience through their reproductive period. The most important cause of primary dysmenorrhea is the enhancement of prostaglandins production and its role in the appearance of the pain. The purpose of this study was to compare the effect of acupressure and vitamin E in reduction of the severity of pain in primary dysmenorrhea.
Materials & Methods: This was a randomized clinical trial study to compare the effect of the pressure point Sanyinjiao medication and vitamin E on dysmenorrhea. In this study, 100 female students between 18 t0 22 years of age were recruited. The students were randomly allocated into two groups: pressure medication group, and vitamin E group. In the first cycle, no treatment was used. But during the next two cycles, with the start of pain in the pressure medication group, the Sanyinjiao point was pressured for 20 minutes and in the Vitamin E group, each subject used one pill of Vitamin E (200 units), daily. The necessary data was collected by questionnaire and Andrish- Millsom scale of dysmenorrhea. Mann-Whitney, Fridman, Wilcoxon, chi-square and t-test were used for data analysis.
Results: The present study revealed that there was significant differences in the rate of pain during the cycles in both groups. There was a significant difference in pain intensity for each group before and after the treatment (P<0.05). Significant difference was found between two groups in the duration of pain in second months (P<0.05).
Conclusion: The findings showed that acupressure at Sanyinjiao point can be used as an effective, available, cost effective intervention for reducing pain in dysmenorrheal