Science editor: vacant science@imprint.uwaterloo.ca
Face the cold A new North American standard gves a more accurate measure of wind chdl Kourtney Short IMPRINT STAFF
If you woke up one morning and heard a forecast of -35'C with wind chill, would you consider staying home? A survey conducted in 1999 by the Meteorological Service of Canada revealed that Canadians take wind chill seriously -82 per cent of Canadians use wind chdl information to decide how warmly they should dress. Wind chill is a measure of the way people experience cold and wind; therefore it cannot be measured directly. Rather, it is calculated using a mathematical model. Before the introduction in October 2001 ofa North American standard, wind chill was expressed in several different ways. In Saskatchewan and Manitoba, it was commonly expressed as a c o o h g rate, in Alberta as a number of minutes for skin to freeze and elsewherein Canada as an equivalent temperature. The new formula replaced the Siple-Passelequation,which had been in use since the 1940s. The SiplePassel equation is based on experiments conducted by Antarctic explorers Paul Siple and Charles Passel in 1939. Sipleand Passel placed smallplastic cylinders filledwith water outside under differenttemperatureandwind
Neal Moogk-Soulis SPECIAL TO IMPRINT
Stephen Hawking turns 60
Stephen Hawking was born in Oxford,England 60 years ago this week. To celebrate, he is taking part in a series of public lectures thatwill examine the future of theoretical physics and cosmology. His lecture series is entitled, "60 years in a nutshell." Hawkingwasoriginally diagnosed with Amyotrophic Lateral Sclerosis, also known as Lou Gehrig's Disease, at the age of 21. This discovery occured after he had completed a very productive academic career at both Cambridgeand Oxford universities. Since he did not know how much longer he would have to live, Hawking decided to continue on with his life and hope that he would achieve all that he wanted to do. As the disease progressed, Hawking required more and more extensive care. Eventually, his ablltty to speak was lost as a result of a trache-
Location Kitchener-Waterloo Ottawa Lloydminster (SK) Mayo (W Peace River (AB) Fort Nelson (BC) Churchill (MB)
Temperature
Wind Speed
Equiv. Temp.
1°C
22 kmlh 15 km/h 28 kmlh 15 kmlh 11 kmlh 13 kmlh 15 kmlh
- 10°C - 9°C - 16°C - 15°C - 13°C - 19°C - 21°C
- 1°C - 2°C - 6°C - 7°C
- 11°C - 11°C
Wind Chill Index
-4
-6 -9
- 12 - 12
- 17 - 18
I
CHART COMPILED USING VALUES FROM THE ENVIRONMENT CANADA WEB SITE AT 930 A.M.ON JANUARY 9 A VALUE OF 6 KWH WAS USED FOR WALKING SPEED WHEN CALCULATING EOUIVALENT TEMPERATURE
I
conditions and measured the time it would take the water to freeze. Using the results of the relationship between cooling rate and wind, they developed an equationthat gives a wind chill factor in units of watts per metre squared,or energy lost per unit area per unit time. The SiplePassel equationis:wind chdl factor = 0.323 * (18.97 * Vo5- V + 37.62) * (33 -T) whereV is the wind speed in km/h at an altitude of 10 metres and T is the ambient temperature in OC. Because many Canadians had difficulty understanding wind chill factor, the media began reporting wind chill as an equivalent temperature, which was calculated using the following modifiedversionof the SiplePassel equation: equivalent temperature = 33 - (18.97 * V 5- V +
37.62)/(18.97 * VP.5-Vc + 37.62) * (33 - T), where Vr is a person's average waking speed for which values between six and eight km/h were in use. Ideally, people would experience the same cooling on a calm day at the equivalent temperature as they did under the actual weather conditions. The resulting equivalenttemperatures were misleading, giving a value for equivalent temperature that was lower than what people actually experienced. This was caused by the following flawed assumptions. The equation uses the wind speed at a height of 10 metres, the standard height at which anemometers (wind measuring devices) are placed, while the wind experienced by an average person at a height of less than two
metres is significantly lower. The average walking speed was inconsistentlyreported and universally too high. - Also, humans lose heat differently than plastic cylinders of water. In search ofa more realisticmodel, experimentswere conducted in June 2001 at the Defense and Civil Institute of Environmental Medcine in Toronto. This was to determine how quickly the human face loses heat under different wind and temperature conditions. The six male and six female participants completed four 90-minute walks on a treadmill in a refrigerated wind tunnel. The temperature was varied between 10°C, O°C and -lO°C and the wind speed between 2 m/s, 5 m/s and 8 m/s. During one of the walks at 10°C, the participants had
otomy operation. With the help of several foundations, Hawking was fitted with a speech system which allowed hun to communicatehis thoughts andideas. In the past 40 years, those thoughts and ideas have made Hawking one of the most well known and important physicists in the world. He has contributed to many theories includmg Einstein's Theory of Relativity and he has worked towards a Grand Unification Theory which would lit& Einstein's Grand Relativity with Quantum Theory. Hawking's most popular bookwas published in 1988, entitled A Brief H i ~ t o yof Time, in which he took complex theories and cutting edge physics and cosmologyand explained them in terms that common people would understand. Hawking's latest book is entitled The Universe in a Nutshell, a sequel to A Brie-fHiftoy ofTime. In tlus book, Hawking revisits all of the old topics that he discussed and updates them usingdiscoveriesthat have been made since 1988. Stephen Hawking continues to balance family life (he has three children and one grandchild), research into theoretical physics and an extensive programme of travel and public lectures.
The box top says it all
would be elther through a satellite dish or cable All output would be directed through television screens and home stereo systems. Though Mom Digtal is the first to launch one of these demces, there are signs that other compames wdl soon follow. Bdl Gates, Mcrosoft founder, gave a sneak preview of a product in development codenamed 'W to be used w t h the Xbox system.
A new trend in home entertainment may be coming to a house near you. Unveiled this year at the ConsumerElectronics ShowinLasVegas, the Moxi Media Center aims to centraltze all home entertainmentwithin one device. Rather then have many devices stacked around a home, the Media Center will have a personal video
Complete home entertainment, all-in-one.
recorder, a music jukebox for accessing tiles, and a CD/DVD player. The box will also have the ability to service instant messaging and emad, as well as having the capacity to r y a wireless network. Connection to the outside world
Other companies are also racing to launch products which could be as influential to home entertainment as the introduction of the VCR These new innovations could allow users to revolutionize theirhome entertainment experience.
appropriate to the simulatedweather, but their faces were exposed. Sensors affixed to their faces measured skin temperature and heat loss. While walking, each participant also had a rectal thermometer in place to measure core temperature. Randall OsczevskioftheDCIEM and Maurice Bluestein of the Purdue University in Indiana used the resulting data in developing the wind chdl index, which expresses wind chill as an equivalent temperature.The equation is: wind chdl index = 13.12 + 0.6215 * T - 11.37 * V16+ 0.3965 * T * V".16, where T is the ambient temperature in OC and V is the wind speedinkm/h at 10 metres. Thenew equation continues to use a wind value measured at standardanemometerheigbt, but corrects for the lower wind speed at human height by multiplying by a factor of 2/3. The new wind chdl index represents a dramatic improvement over past measures of wind chill. Currently underway is the idea to develop a model that includes the warming effect of solar radation on the wind chill index. For moreinformation,pleasevisit theEnvironment Canada Web site at www.msc-smc.ec.gc.ca/windchill/.
Eyes bring a whole new perspective
Scientists in Japan have created the first artificial eye, out of stem cells. The eye tissue was implanted in tadpoles and has not yet been rejected. Makoto Asashima, professor at Tokyo, has been in charge of the research. The process of creating an artificial eye involves collectingstem cells from embryonic frog cells. By altering the retitoic acid in the stem cells, the cells are triggered to develop differently. A high concentration develops ear cells and a lower concentratiofi triggers eye cell development. After being treated with the retitoic acid, the cells were then implantedinto tadpoleswho previously had one eye removed. Later examinationhas shownthat the cells have been connected to the optic nerve and that the eye is operatingnormally. Since thecells are stem cells rather than cells from a fully developed organism, there has been no rejection of the new eye. It is thought that eventually this process can be used for humans who have impaired vision.