Investigations on the respiration of the Neotropical fish, Colossoma macropomum (Serrasalmidae). The influence of weight and temperature on the routine oxygen consumption

The influence of weight and temperature on the routine oxygen consumption of Colossoma macropomum, a Neotropical fish species of the family Serrasalmidae, was investigated using a constant flow respirometer. Plotted on a double logarithmic grid, oxygen consumption increases linearly with weight. Slopes of 0.64 at 25 and 30 °C, and 0.78 at 35 °C were obtained. Because of the significant difference in the slopes, a general value could not be provided. The metabolic rate of a 100 g fish increases from 103.7 to 191.5 and 289.7 mg O2/kg/h at 20, 25, and 30 °C, respectively. At 35 °C, the oxygen consumption rate decreased to 212.4 mg O2/kg/h. The metabolic rate is comparable to those of other tropical fish species. Obviously, Colossoma macropomum is well adapted to the constant temperature conditions of its Neotropical habitats

The 10 Tesla muSR instrument: detector solutions

Solutions to the detector system of the High-Field muSR instrument at the Paul Scherrer Institut (PSI) in Switzerland are presented. The strict technical requirements are fulfilled through the application of Geiger-mode Avalanche Photodiodes.Comment: 6 pages, 4 figure

Kinetic Modelling for Tar Evolution and Formation in a Downdraft Gasifier

Biomass gasification modeling is a powerful tool used to optimize the design of a gasifier. A detailed kinetic model was built by the current authors [1] to predict the behavior of air blown downdraft gasifier for a wide range of materials within the range of (38≤C≤52) %, (5.2≤H≤7) %, and (21.7≤O≤45) %. The model was verified and showed a good stability for a wide range of working parameters like equivalence ratio and moisture content. In the current research, 4 main tar species are added to the model to represent tar formation using detailed kinetic reactions. The yield of tar species is discussed for different zones of a gasifier based on temperature of each zone. Mass and energy balance are calculated. 18 different kinetic reactions are implemented in the kinetic code to predict the optimum working conditions that leads to the production of higher value producer gas. Results conclude that using ER of 0.3 with moisture content levels lower than 10% will lead to the production of higher yields of syngas with lower amounts of tar

Review of \u3cem\u3eThe Future of Capitalism: Facing the New Anxieties\u3c/em\u3e by Paul Collier

Book review of: Paul Collier, The Future of Capitalism: Facing the New Anxieties. HarperCollins (2018), 256 pages

Accretion mode changes in Centaurus X-3

We report here discovery of the existence of two different accretion modes in the high mass X-ray binary pulsar Cen X-3 during its high states. The multiband X-ray light curves of Cen X-3 lasting for more than 3400 days obtained with the All Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) shows many episodes of high and low X-ray intensities. The high intensity phases last between a few to upto 110 days and the separation between two high intensity phases also varies widely. One remarkable feature deduced from the RXTE-ASM light curves is that during these high intensity phases, Cen X-3 manifests in two very distinct spectral states. When the source makes a transition from the low intensity phase to the high intensity phase, it adopts one of these two spectral states and during the entire high intensity phase remains in that particular spectral state. During December 2000 to April 2004, all the high intensity episodes showed a hardness ratio which is significantly larger than the same during all the high states prior to and subsequent to this period. It is also found that most of the soft outbursts reach a nearly constant peak flux in the 5--12 keV band. For comparison, similar analysis was carried out on the long term X-ray light curves of three other X-ray binary pulsars Her X-1, Vela X-1, and SMC X-1. Results obtained with these sources are also presented here and we found that none of the other sources show such a behaviour. From these observations, we suggest that Cen X-3 has two different accretion modes and in the course of nine years it has exhibited two switch overs between these.Comment: 5 pages, 5 postscript figures, accepted for publication in Astronomy and Astrophysics Letter