Tuesday, October 30, 2012

Hurricane Sandy visits Boston

I suppose I can now say that I have been through my first hurricane.  Growing up in the Midwest, hurricanes were something that I only heard about on the news.  I would watch videos of rain jacket clad weathermen struggling to stand upright, but I never really expected to see it firsthand.

Hurricane Sandy brought plenty of rain and wind to Boston yesterday, but for us the worst is past.  Yesterday Boston University closed both campuses and the MBTA stopped all mass transit service at 2PM.  My roommates and I stayed home and settled in for a day of matlab homework and studying, as the wind gradually picked up throughout the day.  By early afternoon we were watching people who had gone to work in the morning head home and struggle to stand upright in the wind.  As the day went on, the storm only continued to grow.  According to the National Weather Service, by evening we had reached peak wind gusts of 64mph in the area where I live.  We could see trees across the street swaying back and forth and rain pelted our windows.  This continued for several hours but eventually the winds began to die down and the storm quieted overnight.

Despite the hurricane yesterday, this morning Boston is already getting back to business as usual.  As I walked to work this morning I saw some branches down and leaves littered the streets, but the day feels more like a rainy spring day than the morning after a hurricane.  The MBTA has been running since 8AM and BU officially reopens at 11AM (though many grad students have been back to work for a couple hours already!).  Power is still out for thousands of people across the state but it is slowly being restored and much of the city is already up and running.  [In fact, most of the area where I live never lost power- even during the peak of the storm.]  All in all...Boston dodged the worst of it.

Sadly New York and New Jersey did not fare as well.  Our thoughts and prayers will be with them as they face a long cleanup process and try to put their lives back together.

PS- Science did not stop for the hurricane.  I worked on matlab from home but evidently one of my labmates ran the TIMS during the hurricane and the other was so focused on writing his dissertation he didn't notice that a tree fell in his front yard.  Ah grad student life.

Wednesday, October 24, 2012

TIMS Tutorial: The Basics

Monday morning I finished the first drafts of all three of my NSF graduate research fellowship application essays.  Monday afternoon\Tuesday morning I finished this week's homework set for the applied statistics course I'm taking.  But now it's Wednesday afternoon and today I feel like I haven't completed anything besides discovering new research roadblocks.  It seems like graduate school is full of bursts of fairly impressive productivity followed by lulls where the instrument doesn't work, experiments fail one after another, and the to-do list gets longer and longer but nothing gets marked off.  If anyone with vastly more science experience has tips for how to overcome lulls I'd be happy to listen!

In an attempt to do something productive and work on my science communication skills (I need all the practice I can get...qualifying/comprehensive exams are looming!) I have decided that one of the projects I'm finally going to tackle during my lab work lull is to write about the main instrument that I use in my research.  Plus, I often learn best by teaching!  I've been meaning to do this for a while and if you've seen references in my posts to "the instrument" or "the TIMS" and wondered what on Earth that was..this is the series for you!  Hopefully, today's post will provide necessary background for those of you with little or no exposure to isotope geochemistry.  Next post I'll show you how the samples get loaded onto the machine and eventually we'll talk about how the machine actually goes from the samples to a useful result and what running the TIMS is really like.

The primary instrument we use in my research lab is a "thermal ionization mass spectrometer," which we refer to as "the TIMS" for short.  [Which, incidentally, has lead to several comical instances where people overheard me telling someone that I "date garnet" or "spend a lot of time with the TIMS" and then inquired about the romance in my life after assuming I was talking about a boy! lol] Breaking down the full name of the instrument actually gives a pretty solid overview of the instrument's purpose.  The TIMS uses high temperatures to ionize (break down into individual charged atoms) the sample, separates the ions by mass using an electromagnet, and allows us to measure the relative abundance of ions at specific masses to determine isotope ratios.  If that just went over your head, don't despair yet!  I promise upcoming posts will have pictures and likely use household objects as analogies to break this overview down into manageable parts.

First...a little general background on geochronology and why I use this crazy instrument.  As an 'isotope geochemist,' my goal is to figure out the age of each of my garnet grains and then use those ages to examine bigger questions about how mountains form and the surface of the Earth changes.  Figuring out the age of the garnet is possible because garnet includes trace amounts of a radioactive element called samarium (Sm) that decays to the element neodymium (Nd) at a known rate.  It takes 1.06x10^11 (106 billion) years for enough Sm to decay so that only half of the original amount is left (called the half-life).  Also, garnet is basically never 100% pure...it usually contains little bits of other minerals that we refer to as inclusions.  To borrow an example from my adviser...you can think of it as a chocolate chip cookie.  The cookie is the garnet and the chocolate chips are the bits of other minerals, or inclusions, inside the garnet.  Many of these inclusions contain a different ratio of  Sm to Nd than the pure garnet (just like the chocolate chips and the cookie base would have different ratios of sugar to milk).  Therefore, I use the TIMS to measure the Sm and Nd ratios in the pure garnet and in the inclusions.  Since the ratios are different and the rate of decay is known, when I plot the ratios for the pure garnet and the inclusions I can define a line between two points, called an isochron.
The slope of the isochron = The age of the garnet!

By the time I am ready to walk into the TIMS lab and start an analysis, I have already been working through sample preparation and clean lab chemistry on a single garnet grain for several weeks.  Those week of work result in a set of 4 beakers, each containing a single bead of dried goop about the size of a ballpoint pen's tip.  The four beakers contain the Nd from the pure garnet, the Sm from the pure garnet, the Nd from the inclusions, and the Sm from the inclusions.  Each isochron that results in an accurate age requires all four samples to run successfully on the TIMS, usually with only one shot at getting each one right. 

This is a very simplistic overview of geochronology and mass spectrometry, especially since there are entire courses on the principles of these areas of study.  Basically, once you understand that by measuring isotope ratios of Sm and Nd we can figure out the age of garnet, you understand the purpose of using a TIMS and one of my basic research goals. The remainder of my research examines ways that we can apply these methods to new materials that have never been dated or how the ages that I get tell us about the rates of metamorphism, when sedimentary basins open and close, how metamorphic conditions change over time, and much more.  

Monday, October 1, 2012

A Summer Summary..and on to Year 2!

So...you thought I'd totally forgotten about the blog, right?  It's not that I forgot..but that I forgot to prioritize writing a post amid what turns out to be the craziness of being a graduate student during the summer!  Goodbye summer vacation and hello full-time research!

To briefly catch you up from my long break from writing..here's a brief summary of the summer:

  • I finished my second semester, including completing a grad. course with my adviser in which I was introduced to the computer programs Perplex and TWQ.  Yippee for surviving my intro to thermobarometric modeling!
  • Flew home for baby brother's high school graduation.
  • Most of the summer I was working on a collaborative project with a visiting PhD student from University of Leeds, England.  He came and spent two months in our lab and I was assigned as his "buddy" and helped him learn lab techniques, design a plan of attack, run samples, etc.  Then once he left I have been finishing up the samples he did not complete.  Look for my first coauthored, peer-reviewed paper to hopefully be published in the next year!
  • I also worked on some of my own samples...dating several more "test" detrital garnets from Vermont that were used for a coauthored presentation given by my adviser at the Goldschmidt Geochemistry Conference in June.  I got to go along and attend Goldschmidt as well, which was in Montreal this year!
  • I was Maid of Honor in a wedding back home in July.
  • My family came to visit me in Boston in August.
Now I am officially a second year PhD student!  Although I must admit..being a second year is a lot more pressure than being a first year.  I now have more responsibility, a to-do list that is much longer than I could ever hope to accomplish and qualifying/comprehensive exams looming on the horizon.  Currently I am finishing the last of the samples still lingering from the summer's projects, as well as taking one course (basically an applied stats course for geologists with an intro to Matlab thrown in for good measure).  I am also writing an application for the NSF graduate research fellowship program and trying not to get too worried about quals in the spring.  Sound like fun?

PS- If anyone has awesome advice on applying for an NSF GRFP...I'd love to hear it!