No plague in the NY subway after all (new study)

July 28th, 2016

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Travellers on the New York and Boston subway systems might allow themselves a sigh of relief – Yersinia pestis (the causative agent of plague) and Bacillus anthracis (the causative agent of anthrax) might not be living in the subway systems after all. This is the finding of a new investigation published in the journal mSystems™, May/June 2016; volume 1, issue 3. The paper refutes the findings of a previous study (‘Geospatial Resolution of Human and Bacterial Diversity with City-Scale Metagenomics’ in: CellSystems, Volume 1, Issue 1, p72–87, 29 July 2015.) Here’s a commentary :

“[…] in a recent study of the New York subway, due to incorrect taxonomic classifications, the authors reported observing Yersinia pestis (the causative agent of plague) and Bacillus anthracis (the causative agent of anthrax) as part of the ‘normal subway microbiome.’ These observations led to high-visibility news reports. But improved reanalysis of the same data by Hsu et al. demonstrated that these results were illusory. Hsu et al. found that these pathogens were not part of the normal subway microbiome, either in New York or in an independent sample set from the Boston subway.” [our hyperlink]

And here’s the new paper itself : ‘Urban Transit System Microbial Communities Differ by Surface Type and Interaction with Humans and the Environment’

Note: Before the appearance of this new study, the authors of the original paper had taken steps to publish a follow-up correction and clarification letter – which said “[…] there is no strong evidence to suggest these organisms are in fact present […]” More here at Retraction Watch.

Predictably smelly breathing [podcast 74]

July 27th, 2016

Heavy breathing (that’s smelly) in movie theaters, in response to what’s in the movie, is the subject of this week’s Improbable Research podcast.

SUBSCRIBE on Play.it, iTunes, or Spotify to get a new episode every week, free.

This week, Marc Abrahams  — with dramatic readings by Harvard chemist Daniel Rosenberg — tells about:

The mysterious John Schedler or the shadowy Bruce Petschek perhaps did the sound engineering this week.

The Improbable Research podcast is all about research that makes people LAUGH, then THINK — real research, about anything and everything, from everywhere —research that may be good or bad, important or trivial, valuable or worthless. CBS distributes it, on the CBS Play.it web site, and on iTunes and Spotify).

Purcell’s musings about things that move in gooey stuff

July 26th, 2016

“It helps to imagine under what conditions a man would be swimming at, say, the same Reynolds number as his own sperm. Well you put him in a swimming pool that is full of molasses, and the you forbid him to move any pare of his body faster than 1 cm/min. Now imagine yourself in that condition; you’re under the swimming pool in molasses, and now you can only move like the hands of a clock. If under those ground rules you are able to move a few meters in a couple of weeks, you may qualify as a low Reynolds number swimmer….”

PurcellDrawing

“I come back for a moment to Osborne Reynolds. That was a very great man. He was a professor of engineering, actually. He was the one who not only invented Reynolds number, but he was also the one who showed what turbulence amounts to and that there is an instability in flow, and all that. He is also the one who solved the problem for how you lubricate a bearing, which is a very subtle problem that I recommend to anyone who hasn’t looked into it. But I discovered just recently in reading in his collected works that toward the end of his life, in 1903, he published a very long paper on the details of the sub mechanical universe , and he had a complete theory which involved small particles of diameter 10^{-18} cm. It gets very nutty from there on. It’s a mechanical model, the particles interact with one another and fill all space. But I thought that, incongruous as it may have seemed to put this kind of stuff in between our studies of the sub mechanical universe today.”

Those musings are from the paper: “Life at Low Reynolds Number,” by Edward M. PurcellAmerican Journal of Physics, vol 45, June 1977, pages 3-11, 1977.

 

 

Earworms meet Big Data (on Twitter)

July 25th, 2016

Lassi_Hoover_PortraitBack in 2008, Dr. Lassi A. Liikkanen [pictured] of the Helsinki Institute for Information Technology (HIIT), University of Helsinki, Finland performed a formal scientific study to investigate INvoluntary Musical Imagery (INMI), a phenomenon more commonly known as an Earworm. Now Dr Liikkanen, along with Kelly Jakubowski and Jukka M. Toivanen have for the first time extended the study of earworms into Big Data territory, using Twitter. Notwithstanding the fact that less than 1 in every 100,000 tweets reference earworms, over a period of six months the investigators sifted through 80,620 earworm-related tweets originating from more than 173 countries. Finding that, in general, twitterers don’t much care for earworms.

“We uncovered evidence that the earworm experience is a widespread psychological phenomenon reported in locations throughout the globe. We found that users openly discuss the types of music that they experience as earworms and potential causes and cures for these via their Twitter network. Finally, we discovered that people discuss INMI in more negative emotional terms on Twitter than other topics, including music in general.”

See: ‘Catching Earworms on Twitter: Using Big Data to Study Involuntary Musical Imagery’ in: Music Perception: An Interdisciplinary Journal, Vol. 33 No. 2 (pp. 199-216) 2015

Note for earworm sufferers: Recent work by Victoria J. Williamson et al. draws attention to the possibilities of ‘Cure Tunes’ – citing as an example, ‘Kashmir’ by Led Zeppelin.

[Disclaimer. Improbable cannot independently verify or assure that the so-called ‘Cure Tune’ may not itself initiate INMI in some listeners]

“Why does popcorn jump when it bursts?”

July 24th, 2016

Emmanuel Virot explains, carefully, why he believes popcorn bursts when it jumps:

Details, in writing, burst from the pages of the study “​Popcorn: critical temperature, jump and sound,”  by E. Virot and A. Ponomarenko, published in the Journal of the Royal Society Interface [12, 20141247 (2015)]. Virot  contemplates popcorn at the Hydrodynamics Laboratory at École Polytechnique.

The study begins with the sentence: “Popcorn is the funniest corn to cook, because it jumps and makes a ‘pop’ sound in our pans. ”