Sarita Rani

Constraints on cosmological parameters in power-law cosmology

In this paper, we examine observational constraints on the power law cosmology; essentially dependent on two parameters H0 (Hubble constant) and q (deceleration parameter). We investigate the constraints on these parameters using the latest 28 points of H(z) data and 580 points of Union2.1 compilation data and, compare the results with the results of ΛCDM . We also forecast constraints using a simulated data set for the future JDEM, supernovae survey. Our studies give better insight into power law cosmology than the earlier done analysis by Kumar [arXiv:1109.6924] indicating it tuning well with Union2.1 compilation data but not with H(z) data. However, the constraints obtained on and i.e. H0 average and q average using the simulated data set for the future JDEM, supernovae survey are found to be inconsistent with the values obtained from the H(z) and Union2.1 compilation data. We also perform the statefinder analysis and find that the power-law cosmological models approach the standard ΛCDM model as q → −1. Finally, we observe that although the power law cosmology explains several prominent features of evolution of the Universe, it fails in details.

Modified Chaplygin gas cosmology with statefinder diagnostic in lyra geometry

In this paper, we have studied Bianchi type-III cosmological models with modified Chaplygin gas (MCG) having equation of state p = A 1 ? - A 2 ? α , where 0 ≤ A 1 ≤ 1 , 0 ≤ α ? 1 and A 2 is a positive constant, within the framework of Lyras geometry. The statefinder, which is a cosmological diagnostic pair { r , s } has been adopted to characterize different phases of the universe. We have investigated stability of the models. The physical and geometrical properties of the corresponding cosmological models have also been discussed.

Rank Order Statistics Related to a Generalized Random Walk

This paper deals with the derivation of the joint and marginal distributions of certain rank order statistics related to the generalized random walk with steps +1 and −µ by using the extended Dwass technique evolved by Mohanty and Handa (1970). These generalize and extend the results of Saran and Rani (1991a, b).

On Joint Distuibutions Of Rank Order Statisties for Equal Sample Sizes

This paper deals with the two–sample (equal sized)problem where Fa(x)and Ga(x)are the two empirical distribution functions and investigates the null joint and marginal distributions of certain rank order statistics through the technique of DWASS(1967 based on simple random walk with indipendent steps,thus generalizing and unifying the results of DWASS(1967),ANEJA (1975)and MAHENDRA PRATAP(1982)

On the distributions of D+ mn , R+ mn (j) And Q+ mn

This paper deals with the two-sample problem and investigates the joint and marginal distributions of D+ mn the Smirnov one-sided statistic, R+ mn (j), the index where D+ mn is achieved for the jth time (j≤1) and Q+ mn , the number of times D+ mn is achieved.

Distributions based on upcrossings, upward crossings, positive reflections and their runs in a generalized random walk

This paper deals with the derivation of the joint and marginal probability distributions of same rank order statistics related to the generalized random walk with steps +1 and -μ by using the extended Dwass technique evolved by Mohanty and Handa (1970). The rank order statistics considered include number of upcrossings, number of upward crossings, number of positive reflections and their runs.

Generalized random walk and distributions of some rank order statistics

Abstract This paper deals with the derivation of the joint and marginal probability distributions of some rank order statistics related to the generalized random walk with steps 1 and -μ by using the extended Dwass technique. The rank order statistics considered include total length of all sojourns above height r, number of crossings of height r, number of sojourns at height r and the number of sojourns at height r from above (r>0).

On Joint Distributions of Rank Order Statistics for Unequal Sample Sizes

This paper deals with the two—sample (unequal sized) problem where F m (x) and G n(x) are the two empirical distribution functions and investigates the null joint and marginal distributions of certain rank order statistics through the extended Dwass technique based on simple random walk with independent steps given by Aneja (1975).