August 25, 2012
Experts' Experts: The secret of sand castles
Kate Yandell's August 9 New York Times Science section article about how to build taller, thinner sand castles can be summed up as follows: "Mix 99 parts of sand with only 1 part water."
More: "'We found that the optimum water content is very, very low, much lower than what children on the beach would use,' said Daniel Bonn of the University of Amsterdam, whose findings appeared in the journal Scientific Reports."
"A sand castle is made of a network of sand grains glued together by very thin bridges of water. Without any water, sand flows; a perfectly dry sand castle would collapse into a heap. Too much water, on the other hand, creates sand soup."
"But embedded in a matrix of water molecules, sand particles stay in place, somewhat like molecules in solid substances."
"Dr. Bonn said he got the idea for his study on a beach, when he spotted sand castles that stood more than 16 feet tall. He began to build his own columns of sand in his lab, measuring how tall and thin he could make them before they fell down."
"He was surprised to find that he was able to calculate how far wet sand could bend before it buckled, in the same way architects calculate the elasticity of marble or steel."
Read the original paper, including figures and references, here.
[Illustration by Chris Gash]
Bug Bite De-Itcher — Episode 2: Electronic means of suppression
Commented reader John Rausch on yesterday's Therapik post, "These thermal devices do not have good reviews. In Europe they sell small piezoelectric devices that apply a small current to the bite. I have had one for some time and it works quite well for me. I have brought many home for friends and most are pleased as well. For some people, it does not seem to help. Psychological? I have asked the manufacturer, Techmed in Italy, if I can get them in the U.S., and they told me they are considered a medical device and the cost and red tape to get them approved is not worth it to them. Maybe this French Amazon retailer will sell you one illegally. It appears so."
Good Ideas on Paper
By Evan Drolet Cook.
Perfect camouflage during bag check.
No one will know you're carrying.
Holds 4 oz.
"Jorge Luis Borges: The Mirror Man"From Open Culture: "He was Argentina's favorite son, one of the great South American writers of the last century (along with Gabriel García Márquez, Carlos Fuentes, and Mario Vargas Llosa), and the winner of 46 national and international literary prizes. We're talking about Jorge Luis Borges, the master of the postmodern short story. Borges was born in 1899, and to celebrate his 100th birthday (though he died in 1986), Philippe Molins directed the documentary, Jorge Luis Borges: The Mirror Man. The film's major strength (as one reviewer put it) is that it's a 'bit of everything — part biography, part literary criticism, part hero-worship, part book reading, and part psychology.' It runs 47 minutes and includes a fair amount of archival footage. (Watch it in a larger format on Vimeo here.)"
Helpful Hints from joeeze: A USB extension cable beats an extension cord
Why use a bulky extension cord to reach six feet further with a laptop, tablet, or phone?
Instead, use an USB extension cable to connect your device and its charger.
It's cheaper, lighter, less bulky, easier to control, and better looking.
What's not to like?
The View From Below — Michael Rohde
From Junk Culture:
"German photographer Michael Rohde creates virtually impossible views of interiors shot from below the floor. His pictures are made up of hundreds of individual photos."
"Cupboards, drawers and fridges are photographed from below and then reassembled into a single seamless composite image."
[via iGNANT and Kay (Leah)]
U.S. Chalkboard Map
Details and features:
• Wood, canvas, chalkboard fabric
• Wipe clean with damp cloth
• 36"W x 24"H.
• Hand made
$168 (chalk not included).