Quark Hadron Phase Transition and Hybrid Stars

We investigate the properties of hybrid stars consisting of quark matter in the core and hadron matter in outer region. The hadronic and quark matter equations of state are calculated by using nonlinear Walecka model and chiral colour dielectric (CCD) model respectively. We find that the phase transition from hadron to quark matter is possible in a narrow range of the parameters of nonlinear Walecka and CCD models. The transition is strong or weak first order depending on the parameters used. The EOS thus obtained, is used to study the properties of hybrid stars. We find that the calculated hybrid star properties are similar to those of pure neutron stars.Comment: 25 pages in LaTex and 9 figures available on request, IP/BBSR/94-3

Nothing Lasts Forever: Environmental Discourses on the Collapse of Past Societies

The study of the collapse of past societies raises many questions for the theory and practice of archaeology. Interest in collapse extends as well into the natural sciences and environmental and sustainability policy. Despite a range of approaches to collapse, the predominant paradigm is environmental collapse, which I argue obscures recognition of the dynamic role of social processes that lie at the heart of human communities. These environmental discourses, together with confusion over terminology and the concepts of collapse, have created widespread aporia about collapse and resulted in the creation of mixed messages about complex historical and social processes

Digital signal processor implementation and performance evaluation of split capacitor, four-leg and three H-bridge-based three-phase four-wire shunt active filters

In this paper a comprehensive study on the three-phase four-wire (3P4W) shunt active power filter (APF) is carried out on the basis of three system configurations. These three two-level voltage source inverter topologies are compared for 3P4W shunt APF, namely, split capacitor (2C), four-leg (4L) and three single-phase H-bridges (3HB). The performance of all three topologies, under an unbalanced non-linear load condition, is evaluated with a detailed digital signal processor (DSP)-based experimental investigation. The steady-state as well as dynamic performance of APF is studied to compensate for current harmonics, reactive power, current unbalance and neutral current. The advantages and limitations offered by each of the topologies are also discussed in brief

Co-existent cristobalite and iridium at 65 Ma, Anjar Intertrappeans, Kachchh, western India

Cristobalite (a high-temperature low-pressure silica polymorph) is reported for the first time from the 65 Ma Anjar intertrappean deposits. It is characterized by a sharp, intense peak (X-ray diffraction) at d-spacing value 4.055Angstrom, followed by a moderate peak at 2.489Angstrom. Its presence is confirmed through Fourier Transform Infrared spectroscopy with absorption bands at 620 and 380 cm(-1). The distribution of volcanic cristobalite coincides with the distribution of iridium in the deposits. When taken in tandem with the absence of shocked quartz, spinels, stishovite and other signatures of an impact origin, this co-existence suggests that the iridium at Anjar is probably of volcanic origin. (C) 2003 Elsevier Ltd