tingilinde

the adventures of charles townes

How the laser happened .. an excerpt from his book

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lewelyn H. Thomas, a noted Columbia theorist, told me that the maser flatly could not, due to basic physics principles, provide a pure frequency with the performance I predicted. So certain was he that he more or less refused to listen to my explanations. After it did work, he just stopped talking to me. A younger physicist in the department, even after the first suc­cessful operation of the device, bet me a bottle of scotch that it was not doing what we said it would (he paid up).

Shortly after we built a second maser and showed that the frequency was indeed remarkably pure, I visited Denmark and saw Niels Bohr, the great physicist and pioneer in the development of quantum mechanics. As we were walking along the street together, he quite naturally asked what I was doing. I described the maser and its performance. “But that is not possible,” he exclaimed. I assured him it was. Similarly, at a cock­tail party in Princeton, New Jersey, the Hungarian mathematician John von Neumann asked what I was working on. After I told him about the maser and the purity of its frequency, he declared, “That can’t be right!” But it was, I replied, and told him it was already demonstrated.

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tabby cats and a reaction diffusion process

Turing appears to have been on the right track

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The question of how cat stripes and splotches are made touches on some of the deepest theoretical puzzles of biology. How does a blob of cells organize itself into a fruit fly, or a panda? What tells the bones in a limb to become a hand, or paw, or the ribbing of a leathery wing? What tells some skin cells to grow dark hair and others lighter hair?

A team of geneticists reported Tuesday in the journal Nature Communications that it had identified a gene in domestic cats that plays a key role in creating the traditional tabby stripe pattern, and that the pattern is evident in embryonic tissue even before hair follicles start to grow.

The inheritance of cat coats — how to breed for this or that pattern — is well known. But how patterns emerge in a growing embryo “really has been an unsolved mystery,” said Dr. Gregory S. Barsh, an author of the new report.

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Here's the paper.  Turing considered his reaction-diffusion patterning mechanism to be his most important work.

 

Developmental genetics of color pattern establishment in cats

 

Christopher B. Kaelin, Kelly A. McGowan & Gregory S. Barsh
Nature Communications volume 12, Article number: 5127 (2021)

Abstract
Intricate color patterns are a defining aspect of morphological diversity in the Felidae. We applied morphological and single-cell gene expression analysis to fetal skin of domestic cats to identify when, where, and how, during fetal development, felid color patterns are established. Early in development, we identify stripe-like alterations in epidermal thickness preceded by a gene expression pre-pattern. The secreted Wnt inhibitor encoded by Dickkopf 4 plays a central role in this process, and is mutated in cats with the Ticked pattern type. Our results bring molecular understanding to how the leopard got its spots, suggest that similar mechanisms underlie periodic color pattern and periodic hair follicle spacing, and identify targets for diverse pattern variation in other mammals.

 

 

 

jocelyn bell burnell

The NY Times has a video on Jocelyn Bell Burnell

She's a star in astrophysics these days, but early on had a Nobel stolen..  

 

honing the capacity to destroy humanity

one of fascism's greatest gifts to america

It's Hans Bethe's birthday - the rise of the Nazi's caused him to leave Germany for America.

 

george stranahan obit

From beer to bulls to physics - certainly one of a kind.

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“Hunter and I decided this is the moment of courage,” Mr. Stranahan recalled. Mr. Thompson reached into a bag he had brought with him, pulled out some lipstick, and gave himself and the boys a once-over.

Patti Stranahan awoke to find her husband and Mr. Thompson, both drunk, with her young son, the whole group wearing lipstick and playing with a venomous spider.

Just your typical night at home. “She turned around and went back to bed,” Mr. Stranahan said.

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early color photography

I was away of early three exposure color photography and that Gabriel Lippman won the Nobel Prize in Physics for his work in color photography, but I had no idea how novel his approach was.

the relevant paper

 

Shedding light on 19th century spectra by analyzing Lippmann photography

Gilles Baechler, Arnaud Latty, Michalina Pacholska , Martin Vetterli , and Adam Scholefield

Significance

Gabriel Lippmann won the 1908 Nobel Prize in Physics for his method of reproducing colors in photography. Despite the significance of this result, there are still misconceptions regarding the approach. We provide a complete end-to-end analysis of the process and show, both theoretically and experimentally, how the spectrum reflected from a Lippmann plate is not the same as the exposing spectrum. In addition, we demonstrate that, given the spectrum reflected from a Lippmann plate, together with the plate’s color absorption properties, the original exposing spectrum can be algorithmically recovered.

Abstract

From uncovering the structure of the atom to the nature of the universe, spectral measurements have helped some of science’s greatest discoveries. While pointwise spectral measurements date back to Newton, it is commonly thought that hyperspectral images originated in the 1970s. However, the first hyperspectral images are over a century old and are locked in the safes of a handful of museums. These hidden treasures are examples of the first color photographs and earned their inventor, Gabriel Lippmann, the 1908 Nobel Prize in Physics. Since the original work of Lippmann, the process has been predominately understood from the monochromatic perspective, with analogies drawn to Bragg gratings, and the polychromatic case treated as a simple extension. As a consequence, there are misconceptions about the invertibility of the Lippmann process. We show that the multispectral image reflected from a Lippmann plate contains distortions that are not explained by current models. We describe these distortions by directly modeling the process for general spectra and devise an algorithm to recover the original spectra. This results in a complete analysis of the Lippmann process. Finally, we demonstrate the accuracy of our recovery algorithm on self-made Lippmann plates, for which the acquisition setup is fully understood. However, we show that, in the case of historical plates, there are too many unknowns to reliably recover 19th century spectra of natural scenes.

 

 

 

on the increase of human lifespan

Science was important, but not close to the entire story.

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The period from 1916 to 1920 marked the last point in which a major reversal in global life expectancy would be recorded. (During World War II, life expectancy did briefly decline, but with nowhere near the severity of the collapse during the Great Influenza.) The descendants of English and Welsh babies born in 1918, who on average lived just 41 years, today enjoy life expectancies in the 80s. And while Western nations surged far ahead in average life span during the first half of the last century, other nations have caught up in recent decades, with China and India having recorded what almost certainly rank as the fastest gains of any society in history. A hundred years ago, an impoverished resident of Bombay or Delhi would beat the odds simply by surviving into his or her late 20s. Today average life expectancy in India is roughly 70 years.

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anti-science and the medical freedom movement in america

An interesting paper on the history of a most dangerous movement.

from The Journal of Clinical Investigation

 

America’s deadly flirtation with antiscience and the medical freedom movement

 

Peter J. Hotez^1,2,3,4,5

¹Department of Pediatrics and Department of Molecular Virology & Microbiology, Texas Children’s Center for Vaccine Development, Baylor College of Medicine, Houston, Texas, USA. ²Department of Biology, Baylor University, Waco, Texas, USA. ³Hagler Institute for Advanced Study, Texas A&M University, College Station, Texas, USA. ⁴James A. Baker III Institute for Public Policy, Rice University, Houston, Texas, USA. ⁵Scowcroft Institute of International Affairs, Bush School of Government and Public Service, Texas A&M University, College Station, Texas, USA.

a dirty drug and an ice cream tub

A must-listen Radiolab episode