788 research outputs found
Holographic Dark Energy Scenario and Variable Modified Chaplygin Gas
In this letter, we have considered that the universe is filled with normal
matter and variable modified Chaplygin gas. Also we have considered the
interaction between normal matter and variable modified Chaplygin gas in FRW
universe. Then we have considered a correspondence between the holographic dark
energy density and interacting variable modified Chaplygin gas energy density.
Then we have reconstructed the potential of the scalar field which describes
the variable modified Chaplygin cosmology.Comment: 4 latex pages, no figures, RevTeX styl
Changes in soil organic matter, plant nutrients and system productivity under conservation agricultural practices in the rice-jute cropping system
Soil organic matter (SOM) is central to soil quality and nutrient cycling. In Bangladesh, depletion of soil fertility is a serious threat to sustainability of agricultural production due to high cropping intensity and agriculture practices based on conventional tillage and residue removal (Rijpma and Jahiruddin, 2004). In this situation, CA practices (minimum tillage, crop residue retention and diverse crop rotations) could be a good option for the improvement of soil quality and crop productivity in Bangladesh. However, CA practices are poorly developed for intensive rice-based cropping system and their effect on SOM, plant nutrients and system productivity have not yet been properly addressed. Hence, the present study was undertaken to monitor the changes in SOM and other plant nutrients with system productivity under CA practices in the rice-jute cropping system in the Low Ganges River Floodplain of Bangladesh
Expanding Universe: Thermodynamical Aspects From Different Models
The pivotal point of the paper is to discuss the behavior of temperature,
pressure, energy density as a function of volume along with determination of
caloric EoS from following two model: & .
The time scale of instability for this two models is discussed. In the paper we
then generalize our result and arrive at general expression for energy density
irrespective of the model. The thermodynamical stability for both of the model
and the general case is discussed from this viewpoint. We also arrive at a
condition on the limiting behavior of thermodynamic parameter to validate the
third law of thermodynamics and interpret the general mathematical expression
of integration constant (what we get while integrating energy
conservation equation) physically relating it to number of micro states. The
constraint on the allowed values of the parameters of the models is discussed
which ascertains stability of universe. The validity of thermodynamical laws
within apparent and event horizon is discussed.Comment: 16 pages, 3 figures(Accepted for publication in "Astrophysics and
Space Science"
Holographic dark energy with time varying parameter
We consider the holographic dark energy model in which the model parameter
evolves slowly with time. First we calculate the evolution of EoS
parameter as well as the deceleration parameter in this generalized version of
holographic dark energy (GHDE). Depending on the parameter , the phantom
regime can be achieved earlier or later compare with original version of
holographic dark energy. The evolution of energy density of GHDE model is
investigated in terms of parameter . We also show that the time-dependency
of can effect on the transition epoch from decelerated phase to
accelerated expansion. Finally, we perform the statefinder diagnostic for GHDE
model and show that the evolutionary trajectories of the model in plane
are strongly depend on the parameter .Comment: 16 pages, 4 figures, accepted by Astrophys Space Sc
Statefinder diagnostic and stability of modified gravity consistent with holographic and new agegraphic dark energy
Recently one of us derived the action of modified gravity consistent with the
holographic and new-agegraphic dark energy. In this paper, we investigate the
stability of the Lagrangians of the modified gravity as discussed in [M. R.
Setare, Int. J. Mod. Phys. D 17 (2008) 2219; M. R. Setare, Astrophys. Space
Sci. 326 (2010) 27]. We also calculate the statefinder parameters which
classify our dark energy model.Comment: 12 pages, 2 figures, accepted by Gen. Relativ. Gravi
Generalized Chaplygin gas model: Cosmological consequences and statefinder diagnosis
The generalized Chaplygin gas (GCG) model in spatially flat universe is
investigated. The cosmological consequences led by GCG model including the
evolution of EoS parameter, deceleration parameter and dimensionless Hubble
parameter are calculated. We show that the GCG model behaves as a general
quintessence model. The GCG model can also represent the pressureless CDM model
at the early time and cosmological constant model at the late time. The
dependency of transition from decelerated expansion to accelerated expansion on
the parameters of model is investigated. The statefinder parameters and
in this model are derived and the evolutionary trajectories in plane are
plotted. Finally, based on current observational data, we plot the evolutionary
trajectories in and planes for best fit values of the parameters of
GCG model. It has been shown that although, there are similarities between GCG
model and other forms of chaplygin gas in statefinder plane, but the distance
of this model from the CDM fixed point in diagram is shorter
compare with standard chaplygin gas model.Comment: 10 pages, 5 figures, accepted in Astrophys Space Sci. (2011
Engineering provitamin A synthesis pathway with β-carotene metabolism in rice endosperm of a restorer line BR827R
Vitamin A deficiency (VAD) is a serious public health problem in South Asia particularly in Bangladesh. Indica rice as a major staple in the country completely lacks vitamin A or compounds with provitamin A activity after milling. A combination of transgenes has been introduced enabling biosynthesis of provitamin A in the endosperm of a restorer line using biolistic system of transformation. The rice seed-specific glutelin promoter (Gt-1 P) was used to drive the expression of phytone synthase (psy), while lycopene b-cyclase (lcy) and phytoenedesaturase (crtI), fused to the transit peptide sequence of the pea-Rubisco small subunit, were driven by the constitutive cauliflower mosaic virus promoter (CaMV35s P). Transgenic plants were recovered through selection with CaMV35sP driven hph (hygromycinphosphotransferase) gene. Molecular analysis demonstrated stable integration and expression of the transgenes. The variable segregation pattern in T1 generation indicated single to multiple insertions of the transgenes in the genome. This is the first report of the development of a transgenic restorer line with carotenogenic pathway into the endosperm for use of hybrid rice improvement
Statefinder Parameters for Different Dark Energy Models with Variable G Correction in Kaluza-Klein Cosmology
In this work, we have calculated the deceleration parameter, statefinder
parameters and EoS parameters for different dark energy models with variable
correction in homogeneous, isotropic and non-flat universe for Kaluza-Klein
Cosmology. The statefinder parameters have been obtained in terms of some
observable parameters like dimensionless density parameter, EoS parameter and
Hubble parameter for holographic dark energy, new agegraphic dark energy and
generalized Chaplygin gas models.Comment: 9 pages, no figure, accepted for publication in IJTP. arXiv admin
note: text overlap with arXiv:1104.2366 by other author
Yield potentiality of maize as relay crop with T. Aman rice under different agronomic management
The experiment was
conducted at the Regional Agricultural
Research Station, BARI, Ishwardi, Pabna,
Bangladesh, during 2013-2014 and 2014-
2015 to introduce maize as relay crop with
T. Aman rice under different agronomic
practices for determine the production
potentials. The experiment was design split
plot with three replications. The agronomic
management practices included four plant
spacing viz. S1=75 cm×20 cm (66666
plants/ha), S2=60 cm×20 cm (83333
plants/ha), S3=50 cm×20 cm (100000
plants/ha) and S4=40 cm×20 cm (125000
plants/ha) and four soil management
practices viz. M1=soil mulching at 25 DAE,
M2=earthing up at 25 DAE, M3=straw
mulching at 25 DAE and M4= without
earthing up and mulching (control). Seeds
were relayed by dibbling manually in
10 days before the harvest of T. Aman rice.
Results showed that an increasing plant
spacing increased leaf area Index (LAI),
total dry matter (TDM), crop growth rate
(CGR) and light energy interception (LEI).
Grain yield was higher in S3 spacing (8.44
t/ha) than others (S4 8.11 t/ha, S2 7.34 t/ha
and S1 6.89 t/ha). Among the soil
management practices, M2 increased LAI,
TDM, CGR, LEI as well as grain yield.
Moreover, M2 and M1 gave similar grain
yield (8.22 t/ha and 8.02 t/ha), that were
significantly greater than other two soil
management practices (M3 7.55 t/ha and M4
6.98 t/ha). From the economic point of
view, combination of S3M1 gave better
performance with gross margin of Tk.
95000/ha and BCR of 2.17. On the basis of
results, S3M1 combination was suitable for
growing maize under relay sowing with
T. Aman rice
Statefinder diagnosis and the interacting ghost model of dark energy
A new model of dark energy namely "ghost dark energy model" has recently been
suggested to interpret the positive acceleration of cosmic expansion. The
energy density of ghost dark energy is proportional to the hubble parameter. In
this paper we perform the statefinder diagnostic tool for this model both in
flat and non-flat universe. We discuss the dependency of the evolutionary
trajectories in and planes on the interaction parameter between
dark matter and dark energy as well as the spatial curvature parameter of the
universe. Eventually, in the light of SNe+BAO+OHD+CMB observational data, we
plot the evolutionary trajectories in and planes for the best fit
values of the cosmological parameters and compare the interacting ghost model
with other dynamical dark energy models. We show that the evolutionary
trajectory of ghost dark energy in statefinder diagram is similar to
holographic dark energy model. It has been shown that the statefinder location
of CDM is in good agreement with observation and therefore the dark
energy models whose current statefinder values are far from the CDM
point can be ruled out.Comment: 23 pages, 6 figure
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