Neutron Stars in a Varying Speed of Light Theory

We study neutron stars in a varying speed of light (VSL) theory of gravity in which the local speed of light depends upon the value of a scalar field $\phi$. We find that the masses and radii of the stars are strongly dependent on the strength of the coupling between $\phi$ and the matter field and that for certain choices of coupling parameters, the maximum neutron star mass can be arbitrarily small. We also discuss the phenomenon of cosmological evolution of VSL stars (analogous to the gravitational evolution in scalar-tensor theories) and we derive a relation showing how the fractional change in the energy of a star is related to the change in the cosmological value of the scalar field.Comment: 15 pages, 2 figures. Added solutions with a more realistic equation of state. To be published in PR

Gauge Coupling Variation in Brane Models

We consider the space-time variation of gauge couplings in brane-world models induced by the coupling to a bulk scalar field. A variation is generated by the running of the gauge couplings with energy and a conformal anomaly while going from the Jordan to the Einstein frame. We indicate that the one-loop corrections cancel implying that one obtains a variation of the fine structure constant by either directly coupling the gauge fields to the bulk scalar field or having bulk scalar field dependent Yukawa couplings. Taking into account the cosmological dynamics of the bulk scalar field, we constrain the strength of the gauge coupling dependence on the bulk scalar field and relate it to modifications of gravity at low energy.Comment: 4 pages, 1 figur

Algorithmization of Bureaucratic Organizations: Using a Practice Lens to Study How Context Shapes Predictive Policing Systems

The current scientific debate on algorithms in the public sector is dominated by a focus on technology rather than organizational patterns. This paper extends our understanding of these patterns by studying the algorithmization of bureaucratic organizations, which is the process in which an organization rearranges its working routines around the use of algorithms. To explore the algorithmization of bureaucratic organizations, we conducted a comparative empirical analysis of predictive policing in Berlin (Germany) and Amsterdam (Netherlands) through in-depth qualitative research. Our study identified two emergent patterns: the ‘algorithmic cage' (Berlin, more hierarchical control) and the ‘algorithmic colleague' (Amsterdam, room for professional judgment). These patterns result from administrative cultures and reinforce existing patterns of organization. The study highlights that two patterns of algorithmization of government bureaucracy can be identified and that these patterns depend on dominant social norms and interpretations rather than the technological features of algorithmic systems