Links for 2018-11-09

  • Specification gaming examples in AI

    A good list of examples where machine learning systems “figure out” how to cheat their fitness function, e.g.:

    ‘Creatures bred for speed grow really tall and generate high velocities by falling over’

    (tags: ai funny humor spreadsheets machine-learning ml fitness-functions)

  • What if the Placebo Effect Isn’t a Trick? – The New York Times

    It is not possible to assay levels of COMT directly in a living brain, but there is a snippet of the genome called rs4680 that governs the production of the enzyme, and that varies from one person to another: One variant predicts low levels of COMT, while another predicts high levels. When Hall analyzed the I.B.S. patients’ DNA, she found a distinct trend. Those with the high-COMT variant had the weakest placebo responses, and those with the opposite variant had the strongest. These effects were compounded by the amount of interaction each patient got: For instance, low-COMT, high-interaction patients fared best of all, but the low-COMT subjects who were placed in the no-treatment group did worse than the other genotypes in that group. They were, in other words, more sensitive to the impact of the relationship with the healer. The discovery of this genetic correlation to placebo response set Hall off on a continuing effort to identify the biochemical ensemble she calls the placebome — the term reflecting her belief that it will one day take its place among the other important “-omes” of medical science, from the genome to the microbiome. The rs4680 gene snippet is one of a group that governs the production of COMT, and COMT is one of a number of enzymes that determine levels of catecholamines, a group of brain chemicals that includes dopamine and epinephrine. (Low COMT tends to mean higher levels of dopamine, and vice versa.) Hall points out that the catecholamines are associated with stress, as well as with reward and good feeling, which bolsters the possibility that the placebome plays an important role in illness and health, especially in the chronic, stress-related conditions that are most susceptible to placebo effects.

    (tags: placebo comt health healthcare medicine enzymes brain)

  • Deadlines, lies and videotape: The tale of a gRPC bug

    HostedGraphite decided to use gRPC as an internal inter-service protocol and ran into a basic protocol bug — it does not default to using an application-level keepalive on the TCP channel so can block indefinitely if sending-side buffers fill up. Always use application-level keepalives and don’t trust TCP

    (tags: tcp protocols keepalive grpc rpc architecture networking)

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