The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

Use of psyllium (isubgol) husk as an alternative gelling agent for the culture of prokaryotic microalgae (Cyanobacteria) Chroococcus limneticus Lemmermann and eukaryotic green microalgae (Chlorophyta) Scenedesmus quadricauda (Turpin) Brebisson

Agar is popularly used as gelling agent to obtain in vitro culture of prokaryotic and eukaryotic microalgae. Exclusive use of agar is resulting in over exploitation of its resources and makes itessential to look for alternative and cheap sources. The study reports in vitro culture of prokaryotic microalgae (Cyanobacteria) Chroococcus limneticus and eukaryotic green microalgae (Chlorophyta)Scenedesmus quadricauda on BG11 medium solidified with 15 g L-1 agar or 10, 15, 20, 25, 30, 35 and 40 g L-1 psyllium (isubgol) husk as gelling agent. The results demonstrated that prokaryotic microalgae C.limneticus was less appropriate for culture on psyllium husk gel compared to eukaryotic green microalgae S. quadricauda. However, the cells of C. limneticus could be multiplied on 10 or 15 g L-1psyllium husk as gelling agent. The highest number of 642000 cells mL-1 of C. limneticus on 15 g L-1 psyllium husk were far lower than 722000 cells mL-1 on agar gelled medium (control). Contrarily, thecells of S. quadricauda could be multiplied on all concentrations of psyllium husk. Compared to the highest number of 546000 cells mL-1 of S. quadricauda on 15 g L-1 agar (control), the highest number of538000 cells mL-1 was recorded on 15 g L-1 psyllium husk gel. The results indicated very similar and comparable cell multiplication behavior of S. quadricauda on agar or 15 g L-1 psyllium husk anddemonstrate the advantage of the very cheap alternative gelling agent psyllium husk over expensive agar for possible use in analytic experiments pertaining to eukaryotic green microalgae