Bias of Maximum-Likelihood estimates in logistic and Cox regression models: A comparative simulation study

Parameter estimates of logistic and Cox regression models are biased for finite samples. In a simulation study we investigated for both models the behaviour of the bias in relation to sample size and further parameters. In the case of a dichotomous explanatory variable x the magnitude of the bias is strongly influenced by the baseline risk defined by the constants of the models and the risk resulting for the high risk group. To conduct a direct comparison of the bias of the two models analyses were based on the same simulated data. Overall, the bias of the two models appear to be similar, however, the Cox model has less bias in situations where the baseline risk is high

Children's views of death

Death is very much a part of the everyday thoughts of children. It is part of the games they play, the stories they hear, and the videos they watch. Sadly, for some children it is also part of their everyday lives—their lived experience in the face of a life-threatening illness, war, violence, or natural disaster. Starting from the position that a child is a sentient, social, emotional, spiritual being embodied in a biological organism we look at how children’s views develop, and how they are manifest in art, play, and conversations with family, friends, and professionals. We see children as active agents in their worlds—interpreting the behaviour of others and acting on the basis of those interpretations. Children see, sense, and notice, and correspondingly, register and make inferences from what they observe inside and outside of themselves. We attend not only to age and stage of development, but also to the dynamic relationship between age, stage, and experience as they come to bear on the children and their worlds at given points in time. Working from this perspective we explore children’s views of death and dying in a variety of situations, from a variety of perspectives—cognitive, cultural, social, and emotional—as a first step in developing guidance for talking with children who are themselves ill and dying, and their siblings. We address three questions and offers suggestions for talking with ill children and their siblings about death: 1. What do children know and understand about death and dying? / 2. Where do children’s ideas about death and dying come from? / 3. How should we address their questions and concerns on this most fundamental question of human existence? The chapter draws on an extensive review of the literature on well and ill children’s views of death as well as the co-authors’ ethnographically based research with ill children, their parents, siblings, and clinicians involved in their care and treatment; highlighting the social nature of death and dyin

Thermal conductance of thin film YIG determined using Bayesian statistics

Thin film YIG (Y$_3$Fe$_5$O$_{12}$) is a prototypical material for experiments on thermally generated pure spin currents and the spin Seebeck effect. The 3-omega method is an established technique to measure the cross-plane thermal conductance of thin films, but can not be used in YIG/GGG (Ga$_3$Gd$_5$O$_{12}$) systems in its standard form. We use two-dimensional modeling of heat transport and introduce a technique based on Bayesian statistics to evaluate measurement data taken from the 3-omega method. Our analysis method allows us to study materials systems that have not been accessible with the conventionally used 3-omega analysis. Temperature dependent thermal conductance data of thin film YIG are of major importance for experiments in the field of spin-caloritronics. Here we show data between room temperature and 10 K for films covering a wide thickness range as well as the magnetic field effect on the thermal conductance between 10 K and 50 K

Temperature dependent relaxation of dipole-exchange magnons in yttrium iron garnet films

Low energy consumption enabled by charge-free information transport, which is free from ohmic heating, and the ability to process phase-encoded data by nanometer-sized interference devices at GHz and THz frequencies are just a few benefits of spin-wave-based technologies. Moreover, when approaching cryogenic temperatures, quantum phenomena in spin-wave systems pave the path towards quantum information processing. In view of these applications, the lifetime of magnons$-$spin-wave quanta$-$is of high relevance for the fields of magnonics, magnon spintronics and quantum computing. Here, the relaxation behavior of parametrically excited magnons having wavenumbers from zero up to $6\cdot 10^5 \mathrm{rad~cm}^{-1}$ was experimentally investigated in the temperature range from 20 K to 340 K in single crystal yttrium iron garnet (YIG) films epitaxially grown on gallium gadolinium garnet (GGG) substrates as well as in a bulk YIG crystal$-$the magnonic materials featuring the lowest magnetic damping known so far. As opposed to the bulk YIG crystal in YIG films we have found a significant increase in the magnon relaxation rate below 150 K$-$up to 10.5 times the reference value at 340 K$-$in the entire range of probed wavenumbers. This increase is associated with rare-earth impurities contaminating the YIG samples with a slight contribution caused by coupling of spin waves to the spin system of the paramagnetic GGG substrate at the lowest temperatures