Month: February 2017
Checkin Eagle Rock Branch Library
🔖 Causal Entropic Forces, Phys. Rev. Lett. 110, 168702 (2013)
Recent advances in fields ranging from cosmology to computer science have hinted at a possible deep connection between intelligence and entropy maximization, but no formal physical relationship between them has yet been established. Here, we explicitly propose a first step toward such a relationship in the form of a causal generalization of entropic forces that we find can cause two defining behaviors of the human “cognitive niche”—tool use and social cooperation—to spontaneously emerge in simple physical systems. Our results suggest a potentially general thermodynamic model of adaptive behavior as a nonequilibrium process in open systems.
🔖 Thermodynamic Uncertainty Relation for Biomolecular Processes, Phys. Rev. Lett. 114, 158101 (2015)
Biomolecular systems like molecular motors or pumps, transcription and translation machinery, and other enzymatic reactions, can be described as Markov processes on a suitable network. We show quite generally that, in a steady state, the dispersion of observables, like the number of consumed or produced molecules or the number of steps of a motor, is constrained by the thermodynamic cost of generating it. An uncertainty ε requires at least a cost of 2k_B T/ε^2 independent of the time required to generate the output.
🔖 Hayflick, his limit, and cellular ageing | Nature Reviews Molecular Cell Biology
Almost 40 years ago, Leonard Hayflick discovered that cultured normal human cells have limited capacity to divide, after which they become senescent — a phenomenon now known as the ‘Hayflick limit’. Hayflick's findings were strongly challenged at the time, and continue to be questioned in a few circles, but his achievements have enabled others to make considerable progress towards understanding and manipulating the molecular mechanisms of ageing.
🔖 Evidence for a limit to human lifespan | Nature Research
Driven by technological progress, human life expectancy has increased greatly since the nineteenth century. Demographic evidence has revealed an ongoing reduction in old-age mortality and a rise of the maximum age at death, which may gradually extend human longevity. Together with observations that lifespan in various animal species is flexible and can be increased by genetic or pharmaceutical intervention, these results have led to suggestions that longevity may not be subject to strict, species-specific genetic constraints. Here, by analysing global demographic data, we show that improvements in survival with age tend to decline after age 100, and that the age at death of the world’s oldest person has not increased since the 1990s. Our results strongly suggest that the maximum lifespan of humans is fixed and subject to natural constraints.
🔖 Energy flow and the organization of life | Complexity
Understanding the emergence and robustness of life requires accounting for both chemical specificity and statistical generality. We argue that the reverse of a common observation—that life requires a source of free energy to persist—provides an appropriate principle to understand the emergence, organization, and persistence of life on earth. Life, and in particular core biochemistry, has many properties of a relaxation channel that was driven into existence by free energy stresses from the earth's geochemistry. Like lightning or convective storms, the carbon, nitrogen, and phosphorus fluxes through core anabolic pathways make sense as the order parameters in a phase transition from an abiotic to a living state of the geosphere. Interpreting core pathways as order parameters would both explain their stability over billions of years, and perhaps predict the uniqueness of specific optimal chemical pathways.
📕 Finished reading The Science of the Oven by Hervé This
I don’t think he mentioned an oven even once….
Meet Ben! – A Matter-Driven Narrative | Medium
I remember when I first walked through the garage door on Bryant St, to see Corey and Lara’s smiling faces, welcoming us in.
Gorsuch and the Senate — and the ghost of Garland | Medium
In normal times, with a normal (right wing) president, Neil Gorsuch would be a fine nominee for the Supreme Court. One can disagree with…
Donald Trump’s Longtime Doctor Says President Takes Hair-Growth Drug | The New York Times
Dr. Harold N. Bornstein granted the interview after The New York Times asked him to discuss his past and possible future role in Mr. Trump’s care.
Checkin Okanoue Library
Checkin Mayor’s Bicentennial Park
📕 Finished reading Charlotte’s Web by E.B. White
What a lovely little volume, though a bit sappier in the end than I would have liked or expected given the realities of the earlier portions.
I’ve an interesting thesis about what the book is really about. Details to come…
📖 On page 115 of 430 of Dealing with China by Henry M. Paulson, Jr.
Cleaning the Stables in Guangdong was interesting, but could have had some more details and data (or a better case study, given its potential value). Alas it was just a quick overview of two years of work, possibly because editors thought it might be overly boring, but really who is going to read this book, but people who want these types of details.
I find at times in the book, he becomes overly gracious and almost too complimentary which I take to mean that he is still ingratiating himself to colleagues and potential future relations.
The chapter on School for Success could itself have been a better and more in-depth case study, but was a short historical outline.
There are some occasional interesting tidbits hidden throughout the chapters which are generally illuminating, but I wish there were more useful insider tidbits of true value. So far I’m not reading anything much more valuable than could be found in overview newspaper articles covering some of the same topics.