220 research outputs found

    Dynamics and Thermodynamics of (2+1)-Dimensional Evolving Lorentzian Wormhole

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    In this paper we study the relationship between the Einstein field equations for the (2+1)-dimensional evolving wormhole and the first law of thermodynamics. It has been shown that the Einstein field equations can be rewritten as a similar form of the first law of thermodynamics at the dynamical trapping horizon (as proposed by Hayward) for the dynamical spacetime which describes intrinsic thermal properties associated with the trapping horizon. For a particular choice of the shape and potential functions we are able to express field equations as a similar form of first law of thermodynamics dE=TdS+WdAdE=-TdS+WdA at the trapping horizons. Here E=ρAE=\rho A, T=κ/2πT=-\kappa /2\pi , S=4πr~AS=4\pi \tilde{r}_{A}, W=(ρp)/2W=(\rho -p)/2%, and A=πr~A2A=\pi \tilde{r}_{A}^{2}, are the total matter energy, horizon temperature, wormhole entropy, work density and volume of the evolving wormhole respectively.Comment: 20 pages, 4 figures, paper presented at the 3rd Algerian Workshop on Astronomy and Astrophysic

    Testing Techniques Selection: A Systematic Approach

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    Road traffic injuries in Rawalpindi city, Pakistan.

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    Data on road traffic accident (RTA) injuries and their outcome are scarce in Pakistan. This study assessed patterns of RTA injuries reported in Rawalpindi city using standard surveillance methods. All RTA injury patients presenting to emergency departments of 3 tertiary care facilities from July 2007 to June 2008 were included. RTA injuries (n = 19 828) accounted for 31.7% of all injuries. Among children aged 0-14 years females suffered twice as many RTA injuries as males (21.3% versus 11.4%), whereas this trend reversed for the age group 15-24 years (41.9% versus 21.7%). One-fifth of injuries were either fractures or concussion. Severity and outcome of injuries were worse for the age group 45 years and older. For every road traffic death in Rawalpindi city, 29 more people were hospitalized and 177 more received emergency department care. These results suggest the need for better RTA injury surveillance to identify preventive and control measures for the increasingly high road disease burden in this city