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Nov 10

Solving the Problem of Disappearing Science Lab Technicians

One of the hardest issues university researchers face today is the lack of funding for lab technicians. Although it’s frustrating that universities are no longer able to support this type of personnel, can technology close the gap? This is a question we’ve tried to answer in our Desert FMP project in collaboration with BYU.

lab technicians

Source: Simplyhired.com. Job listings for Science Lab Technicians have decreased 38% from March 2013-March 2014

I was talking to my colleague, Rick Gill, several weeks ago, and he had this to say about the disappearance of the previously indispensable lab technician: “We have fewer people in the lab, and the people we have are more expensive. We need to be deliberate in how we use their time. If we can make the entire system more efficient using technology, we’ll use the people we have in a way that is meaningful. In ecology right now, one of the things that we’re beginning to recognize is that the typical process where the lab tech would go out and take ten samples and average them is not what’s interesting. What’s interesting is when it’s been dry for four weeks, and you get a big rain event. This is because the average for four weeks is really low for almost all processes, but the data three days after it rains swamps the previous four weeks. So the average condition means almost nothing in terms of the processes we’re studying for global change. We need technology to take the place of the technician who would be monitoring the weather and trying to guess when the big events will occur.”

To capture these pulses in the Desert FMP project, we’re using a continuous monitoring system that communicates feedback directly to us as the principal investigators. Using advanced analysis techniques, we can painlessly assure that data are being collected properly and important events are never missed. Although we don’t have a technician, the goals of the project are still being met.

What do you think? How have you dealt with the disappearance of the lab tech?

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Dec 11

Burn victim research leads to new method for measuring stomatal conductance

Measuring the stomatal conductance of a leaf should be a pretty straightforward problem.  The conductance is just the flux density of water vapor divided by the concentration difference between the leaf and its surroundings.  Common approaches to this problem involve either flowing air of known vapor concentration over the leaf and measuring how much water vapor is picked up, or sealing a cup of known capacity to the leaf surface and measuring how quickly the vapor concentration in the cup increases.  Both of these, though simple in concept, require quite a bit of expensive equipment to pull off.  We wanted a simpler approach.  We put a humidity sensor in a small tube, the end of which could be pressed against the leaf.  As vapor diffused through the tube the humidity in the tube increased.  The conductance of the tube is easily calculated.  It is the diffusivity for water vapor divided by the tube length.  The leaf conductance could be computed from the tube length, the humidity in the tube and the ambient humidity.  That worked, but it turned out that ambient humidity variations introduced too much error, so we later added a second humidity sensor toward the distill end of the tube. Our approach was very simple, and works well, but it wasn’t a new idea.

stomatal conductance

Cross section of METER’s Leaf Porometer

I read of a similar device in a conference proceedings (I don’t recall the name of the conference)  in 1977 when I was on sabbatical at University of Nottingham in England.  The device wasn’t for leaves.  It was developed by a medical researcher to assess severity of burn injuries, and for use on neonatal infants.  The skin of a non-sweating human is pretty impermeable to water.  A typical conductance is around 5 mmol m-2 s-1.  This is about half the value for a leaf with stomates closed, and about two orders of magnitude lower than leaves with open stomates.  Burned skin, however, is much more permeable, and the permeability is related to the severity of the burn.  A device that could measure the permeability of skin would therefore give information on the severity of the burn.  The researcher built an apparatus, similar to our porometer, with two closely spaced humidity sensors in a diffusion tube.  As I recall, it was somewhat successful, but I’m not aware of it ever having been commercialized or used much after that. The application for infants is also interesting.  Full-term babies have low skin conductances.  I haven’t seen measurements, but assume they are similar to adult conductances.  The skin of premature infants, though, has a much higher conductance.  I don’t know typical conductance values, but do know that, without intervention, the conductance can be so high that evaporative water loss from the baby will reduce body temperature to dangerously low levels, even in an incubator. I don’t know if later work has been done to measure skin conductance, but it is interesting that the first applications of the technology we now use in our porometer was for measuring conductance of the human epidermis, not the epidermis of leaves.

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