Self-Replication in Neural Networks.

A key element of biological structures is self-replication. Neural networks are the prime structure used for the emergent construction of complex behavior in computers. We analyze how various network types lend themselves to self-replication. Backpropagation turns out to be the natural way to navigate the space of network weights and allows non-trivial self-replicators to arise naturally. We perform an in-depth analysis to show the self-replicators' robustness to noise. We then introduce artificial chemistry environments consisting of several neural networks and examine their emergent behavior. In extension to this work's previous version (Gabor et al., 2019), we provide an extensive analysis of the occurrence of fixpoint weight configurations within the weight space and an approximation of their respective attractor basins.

Keeping a child's donor sperm conception secret is not linked to family and child functioning during middle childhood: An Australian comparative study.

BACKGROUND AND AIM: Controversy exists as to whether children conceived using donor sperm should be told about their origins and the possible deleterious effects of secrecy. MATERIALS AND METHODS: The Follow-Up of Children Conceived through Donor Insemination research compares 'family functioning' and 'child well-being' in 62 families where donor-conceived children aged between 5 and 13 years had been 'told' (N = 29) and 'not told' (N = 33) of their genetic heritage. Couples were treated through the Prince Henry's Institute of Medical Research Reproductive Medicine Clinic. Standardised measures of family functioning and child well-being collected from mothers were modelled to estimate mean differences according to knowledge of conception. RESULTS: Mean differences between the two 'knowledge of conception' groups were generally very small and not statistically significant; adjustment for covariates did not make a substantive difference to the interpretation of group differences. Scores on family functioning and child well-being measures were within normal limits for both the 'told' and 'not told' groups. CONCLUSION: Further research on parents' experiences would usefully inform discussion on the forms of education and support that would encourage parents to engage with the issues of disclosure and nondisclosure, and promote transparency as well as societal awareness, acceptance and understanding of this method of family formation.

Grating-based x-ray phase-contrast imaging with a multi energy-channel photon-counting pixel detector.

We have carried out grating-based x-ray differential phase-contrast measurements with a hybrid pixel detector in 16 energy channels simultaneously. A method for combining the energy resolved phase-contrast images based on energy weighting is presented. An improvement in contrast-to-noise ratio by 58.2% with respect to an emulated integrating detector could be observed in the final image. The same image quality could thus be achieved with this detector and with energy weighting at 60.0% reduced dose compared to an integrating detector. The benefit of the method depends on the object, spectrum, interferometer design and the detector efficiency.

Mutual aid systems in the United States for chemical emergencies

This paper focuses on the diverse form of interorganizational mutual aid systems established in American localities to cope with chemical emergencies of an acute nature. Factors underlying the development of such systems and the specific forms they assume are discussed as well as the components of these networks, problems encountered and the consequences of such systems for general emergency planning and the community as a whole (AU)