A molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids

We investigate in detail the initial susceptibility, magnetization curves, and microstructure of ferrofluids in various concentration and particle dipole moment ranges by means of molecular dynamics simulations. We use the Ewald summation for the long-range dipolar interactions, take explicitly into account the translational and rotational degrees of freedom, coupled to a Langevin thermostat. When the dipolar interaction energy is comparable with the thermal energy, the simulation results on the magnetization properties agree with the theoretical predictions very well. For stronger dipolar couplings, however, we find systematic deviations from the theoretical curves. We analyze in detail the observed microstructure of the fluids under different conditions. The formation of clusters is found to enhance the magnetization at weak fields and thus leads to a larger initial susceptibility. The influence of the particle aggregation is isolated by studying ferro-solids, which consist of magnetic dipoles frozen in at random locations but which are free to rotate. Due to the artificial suppression of clusters in ferro-solids the observed susceptibility is considerably lowered when compared to ferrofluids.Comment: 33 pages including 12 figures, requires RevTex

Non-English papers decrease rankings

In applying a set of standardbibliometric indicators to rankthe scientific status of 500universities worldwide for the2010 Leiden Ranking, we havediscovered that the language ofpublication has a dramatic andlargely underestimated effect oncitation-based measurements ofresearch performance.Merit, Expertise and Measuremen

Some modifications to the SNIP journal impact indicator

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Rivals for the crown: Reply to Opthof and Leydesdorff

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On the correlation between bibliometric indicators and peer review: reply to Opthof and Leydesdorff

Opthof and Leydesdorff (Scientometrics, 2011) reanalyze data reported byVan Raan (Scientometrics 67(3):491–502, 2006) and conclude that there is no significantcorrelation between on the one hand average citation scores measured using the CPP/FCSm indicator and on the other hand the quality judgment of peers. We point out thatOpthof and Leydesdorff draw their conclusions based on a very limited amount of data. Wealso criticize the statistical methodology used by Opthof and Leydesdorff. Using a largeramount of data and a more appropriate statistical methodology, we do find a significantcorrelation between the CPP/FCSm indicator and peer judgment.Merit, Expertise and Measuremen

Towards a new crown indicator: An empirical analysis

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