Category: Sciency things

Well, this is interesting.

THE MASSIVE NORTHEAST BLACKOUT of a year ago not only shut off
electricity for 50 million people in the US and Canada, but also shut off the pollution coming from fossil-fired turbogenerators in the Ohio Valley. In effect, the power outage was an inadvertent experiment for gauging atmospheric repose with the grid gone for the better part of the day. And the results were impressive. On 15 August 2003, only 24 hours after the blackout, air was cleaner by this amount: SO2 was down 90%, O3 down 50%, and light-scattering
particles down 70% over “normal” conditions in the same area. The haze reductions were made by University of Maryland scientists scooping air samples with a light aircraft. The observed pollutant reductions exceeded expectations, causing the authors to suggest that the spectacular overnight improvements in air quality “may result from underestimation of emission from power plants, inaccurate representation of power plant effluent in emission models or unaccounted-for atomospheric chemical reactions.” (Marufu et
al., Geophysical Research Letters, vol 31, L13106, 2004.)

Perhaps it will start people thinking a little more about what gets spewed out of industrial and power generating plants. One can only hope.

From Physics News Update 696

There’s another interesting new distributed computing project on the horizon coming soon. Like SETI@Home or Distributed.net, Einstein@Home is a project aiming to recruit masses of personal computers to process data from the LIGO (Laser Interferometer Gravitational-wave Observator) project. The purpose of LIGO is to look for gravitational waves by measuring teeny tiny changes in the length of the two arms of the observatory that might be caused by gravitational waves.
From the Einstein@Home homepage:

Einstein@Home is a project developed to search data from the Laser Interferometer Gravitational wave Observatory (LIGO) for signals coming from rapidly rotating neutron stars, known as pulsars. Scientists believe that some pulsars may not be perfectly spherical, and if so, they should emit characteristic gravitational waves, which LIGO will begin to detect in coming months.
Bruce Allen of the University of Wisconsin-Milwaukee’s (UWM) LIGO Scientific Collaboration (LSC) group is leading the development of the Einstein@Home project.
Einstein@Home is one, small part of the LIGO scientific program. It is being set up as a distributed computing project, which means that it relies on computer time donated by private computer users like you to search for pulsars.

The project is scheduled to start sometime in 2005 as one of the events for the World Year of Physics 2005, so sign up now to get the word when it starts!
Found at UIUC‘s Physics Blog.

We’ve been teaching our first year (second year now) residents about nuclear medicine physics, and one of the topics we’ve covered is producing radionuclides for medical use. So I’m trying to whip up a spreadsheet that will model the activity of a typical Mo-Tc radionuclide generator to show off transient equilibrium and what happens when the generator is eluted.
Modelling the Mo/Tc activity in the generator is easy. What I’m finding a little more difficult is including the effects of generator elution where some of the Tc activity is removed from the generator. I’m thinking if I can reformulate the transient equilibrium equation as a recursive equation that looks something like A(t+dt) = f(A(t)) then I can get it to work. Spreadsheets are good at dealing with recursive equations. Should be simple.

Continue reading “Modelling a radionuclide generator in Excel”

Tons of pictures from Cassini today. Most of them are closeups of the rings during the orbital insertion. Very cool if you’re into that kind of thing. For the rest, it’s just a bunch of boring pictures of grey stripes.
Images at JPL and NASA
Images from CICLOPS

In just two short days, Cassini will fire it’s engines to slow down for Saturn orbit. 15 years in the making and after an almost 7 year trip, it’s finally arriving. Looking forward to some pretty sweet data from Cassini and later from Huygens when it drops down to Titan.