Non-equilibrium phenomena and molecular reaction dynamics: mode space, energy space and conformer space

status: publishe

A simulation of a message passing protocol for a network of transputers

With decreasing cost and size of processors and more sophisticated demands of computer users, it is becoming popular to execute programs in parallel on a distributed network. Processors communicate through shared memory or hard-wired links depending on the hardware and topology of the system. Simulation is an appropriate tool for the investigation of system throughput, and the projection of system behavior under various workloads. In this paper is described the configuration and communication protocol of an INMOS Transputer network, and the construction, verification, and validation of a detailed simulation model for the network. Results obtained from the execution of the model, projecting system behavior under both heavy and moderate workloads, are presented. The most significant results obtained indicate that system throughput is severely degraded when increases are made to either message traffic distance or network buffer size. Several areas for further research are suggested, including an alternative topology for large networks

The redshift evolution of the baryonic Tully-Fisher relation in Simba

The baryonic Tully-Fisher relation (BTFR) is an important tool for constraining galaxy evolution models. As 21-cm HI emission studies have been largely restricted to low redshifts, the redshift evolution of the BTFR is yet to be fully studied. The upcoming LADUMA survey (Looking At the Distant Universe with the MeerKAT Array) will address this. As preparation for LADUMA, we use the Simba hydrodynamical galaxy formation simulation from the Simba-hires (25 h$^{-1}$ Mpc)$^{3}$ run to generate rotational velocity measures from galaxy rotation curves ($V_{\rm flat}$) and HI spectral line profile widths ($W50$ and $W20$) at three different redshifts ($z$ = 0, 0.5, and 1). Using these measures, together with the dark matter velocity dispersion, we consider the redshift evolution of the BTFR of Simba galaxies. We find that LADUMA will be successful in detecting redshift evolution of the BTFR, provided that auxiliary data is used to distinguish galaxies with disky morphologies. $W20$ spectral line widths give lower scatter and more pronounced redshift evolution compared to $W50$. We also compare these rotational velocity measures to the dark matter velocity dispersion across redshift and galaxy morphology. We find weak redshift evolution between rotational velocity and the dark matter halo mass, and provide fits for estimating a galaxy's dark matter halo mass from HI spectral line widths. This study with Simba showcases the importance of upcoming, deep SKA pathfinder surveys such as LADUMA, and provides predictions to compare with redshift evolution of the BTFR and galaxy dark matter content from HI rotational velocity measures.Comment: 15 pages, 7 figures. Submitted to MNRA

Electrical transport properties of bulk MgB2 materials synthesized by the electrolysis on fused mixtures of MgCl2, NaCl, KCl and MgB2O4

Electrolysis was carried out on fused mixtures of MgCl2, NaCl, KCl and MgB2O4 under an Ar flow at 600C. Electrical resistivity measurements for the grown deposits show an onset of superconducting transition at 37 K in the absence of applied magnetic field. The resistivity decreases down to zero below 32 K. From an applied-field dependence of resistivity, an upper critical field and a coherence length were calculated to be 9.7 T and 5.9 nm at 0 K, respectively