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March 28, 2008

The Mpemba Effect

Vuugyfio

That's one I missed.

I don't know how, since Aristotle described it around 300-350 B.C.

Of course, the phenomenon wasn't named that back then, which is probably why it didn't ring a bell when I happened on it in Anahad O'Connor's "Really?" column in the March 18, 2008 New York Times Science section.

He wrote, "Under the right circumstances... hot water can freeze more quickly than cool water. Part of the reason appears to be that hotter water loses mass to evaporation, and because it has less mass, less energy is needed to freeze it."

"That phenomenon... described as far back as 350 B.C. by Aristotle... is now known as the Mpemba effect... after Erasto B. Mpemba, a student who noticed it in 1963 while using boiled milk to make ice cream and reintroduced the concept to the scientific literature."

From Wikipedia: "Mpemba first encountered the phenomenon in 1963 in Form 3 of Magamba Secondary School, Tanzania when freezing hot ice cream mix in cookery classes and noticing that they froze before cold mixes. After passing his O-level examinations, he became a student at Mkwawa Secondary (formerly High) School, Iringa, Tanzania. The headmaster invited Dr. Denis G. Osborne from the University College in Dar Es Salaam to give a lecture on Physics. After the lecture, Erasto Mpemba asked him the question, "If you take two similar containers with equal volumes of water, one at 35°C and the other at 100°C, and put them into a refrigerator, the one that started at 100°C freezes first. Why?" only to be the ridiculed by his classmates. After initial consternation, Dr. Osborne confirmed Erasto's finding and they published the results together in 1969."

A much, much more detailed 1998 treatment appears here.

A paper published in 2006 in the American Journal of Physics explained how it happens; the abstract of that report follows.

    The Mpemba effect: When can hot water freeze faster than cold?

    We review the Mpemba effect, where initially hot water freezes faster than initially cold water. Although the effect might appear impossible, it has been observed in numerous experiments and was discussed by Aristotle, Francis Bacon, Roger Bacon, and Descartes. It has a rich and fascinating history, including the story of the secondary school student, Erasto Mpemba, who reintroduced the effect to the twentieth century scientific community. The phenomenon is simple to describe and illustrates numerous important issues about the scientific method: the role of skepticism in scientific inquiry, the influence of theory on experiment and observation, the need for precision in the statement of a scientific hypothesis, and the nature of falsifiability. Proposed theoretical mechanisms for the Mpemba effect and the results of contemporary experiments on the phenomenon are surveyed. The observation that hot water pipes are more likely to burst than cold water pipes is also discussed.

March 28, 2008 at 04:01 PM | Permalink | Comments (1) | TrackBack

Throwback 45 RPM Doormat

Iohuljho

From the website:

    Welcome Record Doormat

    Welcome friends and music fans with our (turn)stylin' 45 RPM doormat.

    Circular shape and bold graphics make it a great addition to small entries or by the porch steps.

    Nylon face with neoprene back. Machine washable.

    24" diameter.

$24.98.

March 28, 2008 at 03:01 PM | Permalink | Comments (1) | TrackBack

BehindTheMedspeak: Dr. John's Herbal Lollipop — Chinese medicine that tastes good

Cfhfh

Long story short: The orange-flavored sugar-free lollipop, invented by UCLA (Go Bruins!) microbiologist Wenyuan Shi, contains an natural ingredient from licorice root which kills Streptococcus mutans, the primary bacterium causing tooth decay.

Shi told Cynthia Lee, writing in the April 2008 issue of UCLA magazine, "Once you clean your teeth, the bacteria just grow back right away.... The human mouth really is the best natural incubator for bacteria – it provides the right temperature and a constant supply of food."

Lee continued, "Among the 700 kinds of bacteria that live in your mouth are a 'dirty dozen,' the culprits that can cause cavities."

Why a lollipop?

"It takes about five minutes to kill bacteria," says Shi. "With chewing gum, most of its contents are released in the first 30 seconds. If you use regular candy, people tend to bite it into pieces before swallowing them. Lollipops take 10 minutes to melt. We find it particularly useful for the elderly and kids."

More details here.

20 lollipops cost $10.

March 28, 2008 at 02:01 PM | Permalink | Comments (2) | TrackBack

Write-on Mugs

Iuouj

From the website:

    Write-On Mugs

    When is a mug more than a mug?

    When it's a game or a handy place to jot down today's "To Do" list.

    Play Tic Tac Toe or Hangman with a friend; make a note to call Mom or clean out the attic.

    Ceramic mug comes with a dry-erase pen.

Each, $8.98.

March 28, 2008 at 01:01 PM | Permalink | Comments (2) | TrackBack

Instant Stadium

Tmp1

Clever.

Tmp

"Today [March 26, 2008] on my way back from work I noticed this HUGE truck. When I came closer I noticed that it carries bleachers for the elections (modarajaat for entekhabaat)."

Tmp3

"They're movable and you can transport them whenever and wherever you want. if you want to take a look, they’re in Mishref near the girls' school."

[via somecontrast.com]

March 28, 2008 at 12:01 PM | Permalink | Comments (0) | TrackBack

Agent-in-Training Onesie: 'Don't wake me, I'll wake you'

Chadtyay

From the website:

    Baby Talk Onesie

    Soft cotton three-snap onesie says what baby is thinking.

    Sizes 3-6 months, 6-12 months, 12-18 months.

    Pink or Blue.

$6.99.

March 28, 2008 at 11:01 AM | Permalink | Comments (1) | TrackBack

BBC iPlayer — 'Making the unmissable, unmissable'

Iplayer

There's something about that British understatement....

This is a wondrous thing.

Long story short: Launched last December, it offers a week's worth of previously broadcast TV content. About 500,000 programs a day are downloaded.

Could prove to be addictive and lead to a signicant decline in job performance.

Fair warning.

*****************

Note added at 10:45 today: "Unfortunately, it only allows UK folks to download."

Thanks, Janice, for the heads-up.

Those Brits — aren't they something?

March 28, 2008 at 10:01 AM | Permalink | Comments (2) | TrackBack

BedUP — Retractable (Into the Ceiling) Bed

1gfdgd

That's different.

2gggds

"Designed by the studio of invention Décadrages and marketed under the brand name BedUP,

3gtyutyt

the bed that falls from the ceiling is an innovation that will save 4 m² in your apartment and for someone who lives in a small space, 4 m² of space is pure gold.

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By day, the bed is stored on the ceiling — the undersurface becomes ceiling with the option of integrated lighting.

5gheryu

At night, the bed descends in the manner of an elevator and stops at a designated height,

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thus avoiding moving furniture previously placed underneath it.

7gyuiyi

Besides being functional, the bed has a clean design that is discreet and elegant."

[via Micle Mihai Cristian and freshome]

March 28, 2008 at 09:01 AM | Permalink | Comments (1) | TrackBack

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