Spherically Symmetric Gravitational Collapse

In this paper, we discuss gravitational collapse of spherically symmetric spacetimes. We derive a general formalism by taking two arbitrary spherically symmetric spacetimes with $g_{00}=1$. Israel's junction conditions are used to develop this formalism. The formulae for extrinsic curvature tensor are obtained. The general form of the surface energy-momentum tensor depending on extrinsic curvature tensor components is derived. This leads us to the surface energy density and the tangential pressure. The formalism is applied to two known spherically symmetric spacetimes. The results obtained show the regions for the collapse and expansion of the shell.Comment: 12 pages, 4 figures, accepted for publication in Mod. Phys. Lett.

Alat Pengusang Cepat IPB 77-1 MM Untuk Penapisan Vigor Daya Simpan Benih Kedelai

Accelerated Aging Machine “IPB 77-1 MM” could be used for soybean seed screening based on the seed storability vigor. The aim of the research was to identify simple, fast and accurate accelerated aging method using accelerated aging machine IPB 77-1 MM. Two methods of accelerated aging test (physical and chemical treatment) were applied to seeds of Anjasmoro soybean variety. The best accelerated aging method was then used to screen seed storability vigor of 23 soybean varieties. Seed storability vigor of 23 soybean varieties were detected using accelerated aging machine IPB 77-1 MM and each was compared with the seed storability vigor of those stored 10 weeks in controlled storage. Results of the experiment showed that using chemical or physical treatment on accelerated aging process were able to decrease seed vigor, but chemical treatment decreased seed vigor faster, more simple and more practical. Accelerated aging machine IPB 77-1 MM could also be used for screening varietal seed storability vigor of soybean using electrical conductivity test

Conformal Ricci collineations of static spherically symmetric spacetimes

Conformal Ricci collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating conformal Ricci collineations is found when the Ricci tensor is non-degenerate, in which case the number of independent conformal Ricci collineations is \emph{fifteen}; the maximum number for 4-dimensional manifolds. In the degenerate case it is found that the static spherically symmetric spacetimes always have an infinite number of conformal Ricci collineations. Some examples are provided which admit non-trivial conformal Ricci collineations, and perfect fluid source of the matter

Nutritional Evaluation and Physicochemical Properties of Fermented Shirezh Dairy Product

Many of the Kurdish traditional dairy products have not been studied thoroughly so far though are still produced at small scale. Dow (sour butter milk) and Shirezh are among these products. Shirezh known to Iraqi Kurds as sour concentrated Dow. The characteristics of Shirezh and Dow were: pH (5.5, 4.05), acidity (2.13%, 1.10%), total solids (18.70%, 5.32%), ash (0.62%, 0.45%), fat (2.57%, 0.8%) and total protein (13.59%, 3.28%) respectively, furthermore the amino acids of Shirezh’s protein found in balanced and acceptable quality. The aim of this research is to introduce Shirezh and Dow to scientific literature and to determine their characterization and nutritional values. Keywords: Shirezh, Dow, Dairy, Fermented, Nutrition, Physicochemical, Amino acids

Evaluating the productivity potential of chickpea, lentil and faba bean under saline water irrigation systems

The information on salinity threshold levels for food legumes when irrigating with saline water is limited and old. In a multi-year study at two sites in the Euphrates Basin, we aimed at (i) evaluating the potential of saline water irrigation for chickpea, faba bean and lentil production; and (ii) using the SALTMED model to determine threshold crop yields based on irrigation water salinity in equilibrium with ambient soil solution salinity. To evaluate 15 accessions each of lentil and chickpea, and 11 accessions of faba bean, three irrigation treatments were used with salinity levels of 0.87, 2.50 and 3.78 dS m-1 at Hassake and 0.70, 3.0 and 5.0 dS m-1 at Raqqa. Aggregated grain yields showed significant differences (p < 0.05) among crop accessions. Calibration and validation of the SALTMED model revealed a close relationship between actual grain yields from the field sites and those predicted by the model. The 50% yield reduction (π50 value) in chickpea, lentil, and faba bean occurred at salinity levels of 4.2, 4.4 and 5.2 dS m-1, respectively. These results suggest that of the three food legume crops, faba bean can withstand relatively high levels of irrigation water salinity, followed by lentil and chickpea

Exogenous melatonin enhances salt stress tolerance in tomato seedlings

Melatonin (N-acetyl-5-methoxytryptamine) is an essential molecule which regulates plant growth and development and alleviates the damaging effects of abiotic stresses. To evaluate the important functions of melatonin in response to salinity stress, the effects of exogenous melatonin on the antioxidant system and growth of tomato (Solanum lycopersicum L.) under 150 mM NaCl stress were investigated. The application of 100 μM melatonin compensated the growth inhibition caused by salt-stress. Melatonin treated seedlings had an increased fresh and dry masses of shoots and roots. The application of 1 - 200 µM melatonin notably enhanced the relative chlorophyll content (SPAD index), root characteristics, and gas exchange in tomato seedlings subjected to salt stress compared to seedlings treated with salt stress alone. Moreover, melatonin pretreatment minimized accumulation of reactive oxygen species and improved activities of antioxidative enzymes including catalase, superoxide dismutase, glutathione reductase, and ascorbate peroxidase.We would like to thank Wang Zhiwei from the College of Horticulture and Landscape Architecture, Hainan University, Haikou for his kind guidance and laboratory equipment. This program was financially supported by the Innovative Team Program of Hainan Natural Science Foundation (2018CXTD334) and the National Natural Science Foundation of China (41871041)

Effect of various nutrient combinations on growth and body composition of rohu (Labeo rohita)

A total of 80 Labeo rohita fingerlings (mean body weight, 14.7 ± 0.08 g and length, 11.0 ± 0.16 cm) were randomly distributed into four treatments with 20 replicates each, for 60 days, to determine the effect of different feed compositions on the growth and body composition of L. rohita. Four isoenergetic (17.05 ± 0.24 kJ g-1) experimental diet viz., control (C), protein rich (PR), fat rich (FR) and carbohydrate rich (CR) were formulated. The proximate composition protein/fat/carbohydrate (P/F/C) of formulated feed were C: P35/F8/C2, PR: P40/F8/C2, FR: P35/F10/C2 and CR: P35/F8/C5. The daily ration size was 5% of fish body weight. The result reveals a highly significant (P≤0.001) difference in specific growth rate (SGR), weight gain (WG) and protein efficiency (PE) among four feeding groups, while differences were significant for feed conversion ratio (FCR). FR showed maximum growth together with high body fat, CR showed low body fat and high proteins. Results indicate that increasing fat up to 9% in diet showed better growth as compared to increasing dietary protein and carbohydratesKey words: Labeo rohita, diet composition, specific growth rate, protein efficiency, body composition