Measuring contagion with a Bayesian, time-varying coefficient model

JEL Classification: C11, C15, F41, F42, G15Contagion, Gibbs sampling, Heteroskedasticity, Omitted variable bias, Time-varying coefficient models

On the decomposition numbers of the Ree groups F42(q2) in non-defining characteristic

AbstractWe compute the ℓ-modular decomposition matrices of the simple Ree groups F42(q2), where q2=22n+1 and n>0, for all primes ℓ>3 up to some entries in the unipotent and one entry in the non-unipotent characters. We determine the smallest degree of a nontrivial irreducible ℓ-modular representation of F42(q2) for all primes ℓ>3 and also obtain results on the 3-modular decomposition matrices of F42(q2)

The decay of space charge in a glassy epoxy resin following voltage removal

The PEA technique is used to measure the distribution of space charge in an epoxy resin after polarisation for one week at an applied field of 7.14kV/mm over a range of temperatures. The decay of the space charge is followed for times up to 114 hours after removal of the voltage and analysed in terms of a number of alternative decay mechanisms. It is shown that the rate-determining stage of the decay mechanism is that of a thermally activated process that has been associated with charge de-trapping. At times greater than 102s the de-trapping process behaves as though the space charge field does not exist and the retention time of the space charge depends only upon the depth of the deepest occupied traps and the temperature

Vector magnetometry using silicon vacancies in 4H-SiC at ambient conditions

Point defects in solids promise precise measurements of various quantities. Especially magnetic field sensing using the spin of point defects has been of great interest recently. When optical readout of spin states is used, point defects achieve optical magnetic imaging with high spatial resolution at ambient conditions. Here, we demonstrate that genuine optical vector magnetometry can be realized using the silicon vacancy in SiC, which has an uncommon S=3/2 spin. To this end, we develop and experimentally test sensing protocols based on a reference field approach combined with multi frequency spin excitation. Our works suggest that the silicon vacancy in an industry-friendly platform, SiC, has potential for various magnetometry applications at ambient conditions