A detailed analysis of structure growth in f(R)f(R) theories of gravity

We investigate the connection between dark energy and fourth order gravity by analyzing the behavior of scalar perturbations around a Friedmann-Robertson-Walker background. The evolution equations for scalar perturbation are derived using the covariant and gauge invariant approach and applied to two widely studied $f(R)$ gravity models. The structure of the general fourth order perturbation equations and the analysis of scalar perturbations lead to the discovery of a characteristic signature of fourth order gravity in the matter power spectrum, the details of which have not seen before in other works in this area. This could provide a crucial test for fourth order gravity on cosmological scales.Comment: 27 pages and 35 figure

Detecting non-Markovianity via uncertainty relations

We present a formalism for detection of non-Markovianity through uncertainty relations. We show that when there is an information back-flow to the system from its environment through CP-divisibility breaking, the Choi-states corresponding to the reduced system evolution contain at least one negative eigenvalue. The consequent break down of uncertainty relations for such states can be used to witness non-Markovian dynamics. We present some relevant examples of the phenomenon for qubit channels. We further prove that square of the variance of a suitable hermitian operator can act as a non-linear witness of non-Markovianity. We finally show that non-Markovianity is necessary in order to decrease the uncertainty of the states undergoing unital dynamics for qubits. This provides another method of certifying non-Markovianity.Comment: 8 pages, 3 figure

The cosmological gravitational wave background from primordial density perturbations

We discuss the gravitational wave background generated by primordial density perturbations evolving during the radiation era. At second-order in a perturbative expansion, density fluctuations produce gravitational waves. We calculate the power spectra of gravitational waves from this mechanism, and show that, in principle, future gravitational wave detectors could be used to constrain the primordial power spectrum on scales vastly different from those currently being probed by large-scale structure. As examples we compute the gravitational wave background generated by both a power-law spectrum on all scales, and a delta-function power spectrum on a single scale.Comment: 8 Page

Report of Acoustic Test on PSLV IS.1/2L Structure

The results of acoustic conducted on PSLV IS.1/2L at Acoustic Test Facility are briefly given. It contains test set up, Instrumentation details and tables of spectral response

Effect of age and physical activity on oxidative stress parameters in experimental rat model

Studies have suggested that regular physical exercise has beneficial effects on the brain by modulating the oxidative stress. There is little information regarding whether swimming exercise could attenuate oxidative stress in the brain. Therefore, the present study was aimed to investigate the effect of physical activity on the oxidative stress parameters in the cerebral cortex and the hippocampus of the aging rat brain. Methods: Male Wistar albino rats of 4-, 12- and 22-months old age were swim-trained in a rectangular glass tank for 30 min/day, 6 days/week with 3% of load for 4 weeks. We examined the levels of protein carbonyls, superoxide radicals and thiols to assess the oxidative stress with exercise in the aging rat brain. Results: Age-related increase in the protein carbonyls and superoxides with decreased thiols were observed. Hippocampus exhibited higher levels of oxidative stress compared to the cerebral cortex. Training significantly attenuated the oxidative stress as carbonyls and superoxides reduced and thiols were enhanced. Conclusion: The findings of this study suggests that physical exercise reduces the oxidative stress in the cerebral cortex and hippocampus and may provide a therapeutic intervention in attenuating age-related oxidative stress in the brain

How Quality, Value and Satisfaction Create Passenger Loyalty: an Empirical Study on Indonesia Bus Rapid Transit Passenger

This study aims to investigate the dimensions of service quality especially in the area of public transport as well asthe role of service quality in enhancing passenger\u27s value, satisfaction and loyalty. Partial Least Squares (PLS) with survey data from 152 BRT passengerswas used by this study. This study found that outcome quality, physical quality and interaction quality are the the primary dimensions of service quality. In addition, this study explained that service quality has a signifiant effect on passenger perceived value, satisfaction and loyalty. Apart from perceived service quality, this study also found that passenger satisfaction and perceived value are the essential determinants of passenger loyalty