Modified gravity a la Galileon: Late time cosmic acceleration and observational constraints

In this paper we examine the cosmological consequences of fourth order Galileon gravity. We carry out detailed investigations of the underlying dynamics and demonstrate the stability of one de Sitter phase. The stable de Sitter phase contains a Galileon field $\pi$ which is an increasing function of time (\dot{\pi}>0). Using the required suppression of the fifth force, supernovae, BAO and CMB data, we constrain parameters of the model. We find that the $\pi$ matter coupling parameter $\beta$ is constrained to small numerical values such that $\beta$<0.02. We also show that the parameters of the third and fourth order in the action (c_3,c_4) are not independent and with reasonable assumptions, we obtain constraints on them. We investigate the growth history of the model and find that the sub-horizon approximation is not allowed for this model. We demonstrate strong scale dependence of linear perturbations in the fourth order Galileon gravity.Comment: 9 pages, 10 figures, references added, final version to appear in PR

Background cosmological dynamics in f(R)f(R) gravity and observational constraints

In this paper, we carry out a study of viable cosmological models in $f(R)$-gravity at the background level. We use observable parameters like $\Omega$ and $\gamma$ to form autonomous system of equations and show that the models under consideration exhibit two different regimes in their time evolution, namely, a phantom phase followed by a quintessence like behavior. We employ statefinder parameters to emphasize a characteristic discriminative signature of these models.Comment: 6 pages, Latex style, 9 eps figures, replaced versions with new references added, Submitted to Phys.Rev.

Prospects of inflation with perturbed throat geometry

We study brane inflation in a warped deformed conifold background that includes general possible corrections to the throat geometry sourced by coupling to the bulk of a compact Calabi-Yau space. We focus specifically, on the perturbation by chiral operator of dimension 3/2 in the CFT. We find that the effective potential in this case can give rise to required number of e-foldings and the spectral index $n_S$ consistent with observation. The tensor to scalar ratio of perturbations is generally very low in this scenario. The COBE normalization, however, poses certain difficulties which can be circumvented provided model parameters are properly fine tuned. We find the numerical values of parameters which can give rise to enough inflation, observationally consistent values of density perturbations, scalar to tensor ratio of perturbations and the spectral index $n_S$.Comment: 7 pages and nine figures; typos corrected, minor comments and clarifications added, revised version to appear in PL

The transient and the late time attractor tachyon dark energy: Can we distinguish it from quintessence ?

The string inspired tachyon field can serve as a candidate of dark energy. Its equation of state parameter $w$ varies from 0 to -1. In case of tachyon field potential $V(\phi)\to 0$ slower(faster) than $1/\phi^2$ at infinity, dark energy(dark matter) is a late time attractor. We investigate the tachyon dark energy models under the assumption that $w$ is close to -1. We find that all the models exhibit unique behavior around the present epoch which is exactly same as that of the thawing quintessence.Comment: 6 pages, 7 eps figures, Revtex style, minor changes, references added, Accepted in Physical Review

Paper Session II-C - Satellite Remote Sensing for Environment and Resource Managment

In the recent years there have been valuable achievements in data pre-processing r image processing and interpretation and other related techniques. These developments in the field of satellite remote sensing have resulted in much more useful studies of environment and resource management. We present a review of some of such studies with emphasis on different land use /landcover features in some urban areas of Pakistan. These studies were made using SPOT multispectral and panchromatic data. Our analysis will be found useful for updating information of different urban features. In the end we present our future programs regarding the resource management and environment using earth resource satellites like LANDSAT and SPOT

US Dollar/IQ Dinar Currency Exchange Rates Time Series Forecasting Using ARIMA Model

The use of currency exchange estimation as a tool for economic planning is being researched as a technique for gaining economic stability. The main purpose of this study is to use the ARIMA model to forecast monthly US dollar and IQ dinar exchange rates. The information was gathered from January 2010 to December 2020. We got the information from the website (sa.investing.com). The minimum value of Root Mean Square Error (RMSE) and the mean absolute error are used to select the optimal model (MAE). ARIMA was found to be the best model for the US Dollar/IQ Dinar series (2, 1,0). This is the forecasted meaning for the future of this exchange rate time series, which indicates a perpetual increase continuously in the next two years. Statgraphics version 15 was the statistical software package utilized to complete this project

Targeted Delivery of Insulin by Psyllium Plant (Plantago ispaghula) based hydrogels/membranes

Developments in therapeutics are the need of hour for the benefit of mankind and to increase the quality of life. Diabetes mellitus is a non-curable disease affecting a great amount of world’s population. This genetic disorder gets worse with time and ultimately leads to various complications like renal failure, lower limb amputation, heart diseases and blindness. Hydrogels for quite recent time are being used for the drug delivery. The present article is related to the fabrication of psyllium based dermal patches insulin drug delivery system that could release insulin in a sustained and controlled manner. Psyllium, a natural polysaccharide, is a medicinally important dietary fiber and drug delivery system has developed a novel insulin loaded psyllium based hydrogels for glucose lowering. They can be used for the transdermal delivery of insulin as hypodermic administration of insulin is painful, complicated, can also results in allergic reactions and infections. For the sustained and steady release of insulin from fabricated hydrogels were also modified with the addition of graphene oxide nanoparticles. To study the structural aspects of these various polymeric networks thus formed were characterized with FTIR (Fourier-transform infrared spectroscopy) and SEM (Scanning electron microscopy) which identifies the interaction/bonding among different functional groups and also indicating the layer of graphene oxide nanoparticles on the surface of hydrogels stage and release related experiments such as degradability, swelling kinetics, swelling ratio and drug kinetics were also performed. Because of its functionalization these unique 3D drug loaded polymeric hydrogels will have the double prospective of diabetes. Different types of psyllium based hydrogels were prepared, and the effect of ph on the release dynamics of insulin from drug loaded hydrogels has been studied to evaluate the drug release mechanism in-vitro and in-vivo. For in-vivo study avian skin was used a model. Fickian diffusion mechanism has been observed for the release of insulin at different ph both in and in-vivo and therefore these drug loaded hydrogels can be potentially used to develop pH-sensitive systems. Keeping in view the results of different analysis it can be concluded that these hydrogels can prove to be very useful for the treatment of diabetes mellitus

The thawing dark energy dynamics: Can we detect it?

We consider different classes of scalar field models including quintessence, and tachyon scalar fields with a variety of generic potential belonging to thawing type. Assuming the scalar field is initially frozen at $w=-1$, we evolve the system until the present time. We focus on observational quantities like Hubble parameter, luminosity distance as well as quantities related to the Baryon Acoustic Oscillation measurement. Our study shows that with present state of observations, one can not distinguish amongst various models which in turn can not be distinguished from cosmological constant. This lead us to a conclusion that there is a thin chance to observe the dark energy metamorphosis in near future.Comment: 7 pages, Revtex Style, 6 eps figures, replaced with revised version, some figures are modified, minor changes, conclusions remain the same, Accepted for publication in Physics Letters