The Frustration of Flow Rate

Since the Deepwater Horizon explosion on April 20th, there has been a lot of speculation about the amount of oil that is actually flowing into the Gulf. The estimates have varied considerably. Yesterday, the US government announced that the amount of oil is likely to be double what was originally estimated, approximately 25,000 to 30,000 barrels per day. But we still do not know for certain, and this is frustrating to many who feel that with the technology we have and the amount of time this has been going on, we should be able to come up with definitive numbers.

Leaving aside speculation about whether or not BP is being upfront about their data, let's take a moment to look at how flow rate is generally calculated and why some of these estimates have been drastically different.

Whether you're a plumber or an oil driller, there is a general formula used to understand the flow rate of a liquid leaving a pipe:

Velocity  X  Pipe Area = Flow Rate

Velocity is a vector quantity and is measured by the speed of an object over time. When we talk about the speed/time, it refers to constant velocity -- both the size of the object and the direction remain the same. Because a pipe is a fixed object, the direction of the oil within it is obviously not going to change. But when it leaves the pipe, it encounters the pressure of water one mile beneath the surface (approximately 500 times greater than at sea level) and other particulates, which can deflect the direction of the flow. How scientists are calculating velocity thus far has been a bit murky. Measuring it within the pipe will generate one number; outside the pipe, another.

Now, the pipe area. This is one number that should actually be pretty straight-forward. The area of a cylinder is the perimeter of the opening multiplied by the height. In this case, it's the perimeter of the pipe opening multiplied times the length of the pipe. One of the reasons we include pipe area in calculating flow rate is because the friction of the inside of the pipe applies force on the liquid.The longer the pipe or shorter the diameter, the greater the force applied. Cutting the pipe increased the perimeter because it removed the valve that was slowing the flow down -- so the flow rate has actually increased since this was done.

In the case of the Gulf, we want to know more than the flow rate -- we want to know the mass flow rate. We want to know how much oil is coming into the area, not just how quickly.

In order to calculate mass flow rate, we need to incorporate density into the equation:

Mass Flow Rate = Density X  Velocity X Pipe Area

Density is measured by dividing the mass of an object by its volume (for more on density, click here). When you have a fixed object, calculating density is rather straight-forward: find its mass, measure its volume, do the math, et viola. Unfortunately, the crude oil coming out of the sea bed in the Gulf is not uniform. It is composed of solid particulate, gas and liquid. And the concentrations of these will vary over time. Add to the mix that BP is injecting dispersants into the pipe, and density becomes even more difficult to calculate. 

Clearly, the fact that this leak is occurring in three places 5,000 feet below the surface of the ocean means that there are more factors at play than simply multiplying a few numbers together. It becomes a matter of getting numbers that accurately reflect the averages for density and velocity, which has been quite difficult considering the locations of the three leaks.

With luck, the leaks will be stopped soon enough so that we no longer have to worry about whose numbers are correct.

Image courtesy of BP/AP

Taking "Obsession" to a Whole New Level

The Wall Street Journal published an article today on some interesting scientific research. Apparently, Calvin Klein's cologne, Obsession, is more than just for men.

As the article notes, zoos all over the world have long been using the practice of spraying perfumes and colognes throughout animal grounds in order to keep them stimulated and curious. At the Bronx Zoo in New York, Curator Pat Thomas decided to see if the types of scent had much affect on the response of cheetahs to the new odors. While a cat's sense of smell may not be as developed as its other senses, the average cat's ability is still 14 times greater than a human's -- which makes those perfumes and colognes particularly pungent, and Thomas' study showed that the big cats have very particular tastes.

Using 24 different types of perfume and cologne, Thomas measured the amount of time it took for the cats to first notice the new scent, and then how long they spent investigating it. The results were varied. Estee Lauder's Beautiful apparently interested the cheetahs for a whopping two seconds. But Klein's Obsession? 11.1 minutes. More than simply investigating the scent, the animals tended to cuddle up next to whatever was sprayed with the cologne.

This research was impressive enough to convince Thomas to share his finding with other scientists studying big cats, and has since had a significant impact on field research. Now, scientists all over the world are able to get better information about the big cats they are studying. As the article noted, one researcher studying jaguars has had a significant increase in usable data. Relying on motion-detecting cameras to record the presence and distinct markings of jaguars, he has managed to lure more of the elusive animals to his camera areas by leaving objects spritzed with the cologne nearby. The Wildlife Conservation Society has even decided to make the use of Obsession-spritzing a regular part of all of their jaguar studies!

Many of these organizations and zoos rely on donations from the public in order to operate -- and this includes donations of scents. If you happen to have some Obsession lying around that you don't think you'll use, contact your local zoo to see if they might like it. And if that's your favorite cologne, you might want to think twice about wearing it the next time you are in the area of big cats...

For more on research methods, visit Visionlearning.com's Process of Science page.

Image courtesy of Bernie Condon at freedigitalphotos.net

To Caffeinate or Not to Caffeinate

Researchers at Bristol University in the UK have something to tell us regular coffee, tea and soda drinkers. That morning pick-me-up isn't really picking us up, it's pushing us down.

In the study about to be published in Nature's journal Neuropsychopharmacology, Rogers et al. share with us that our regular caffeine habits are actually causing a dependency that leaves us in withdrawl. After 16 hours without caffeine, regular caffeine consumers and non-consumers were divided up. Some were given caffeine tablets and others a placebo. The results show that the "post-caffeine levels of alertness [in regular caffeine consumers] were actually no higher than the non/low consumers who received a placebo, suggesting caffeine only brings coffee drinkers back up to 'normal'."*

So what does that tell us regular visitors to the coffee pot? If we want to increase our alertness, we might think about skipping the "regular," grabbing the decaf, and doing something that is proven to increase blood flow to the brain -- like taking a walk.

Image courtesy of Michelle Meiklejohn from freedigitalphotos.com

Modeling the Swallowtail

Modeling has long been used by scientists to replicate and manipulate what they are researching. Physical, conceptual, and computer models have turned out to be important components of scientific research because they allows us to see things. These different modeling forms become incredible useful when studying incredibly large (think solar system) and very small (think atomic) systems. Or, in the case of two researchers at Harvard University, something delicate and fleeting. (To learn more about modeling as a research method, click here.)

Researchers Hiroto Tanaka and Isao Shimoyama have managed to create a model of the swallowtail butterfly's wing. Their research has not only shown how the undulating flight pattern of the swallowtail allows it to conserve energy, but the physiological importance of veins within the wing. By creating a physical model of the butterfly from a thin polymer film and balsa wood (it weighs 0.4 grams, only slightly heavier than the actual creature), they have been able to compare the flight patterns of the model butterflies (with and without veins) to live ones. After recording the live and artificial creatures on high speed film, Tanaka and Shimoyama were able to compare the data and begin to understand how simple up and down movement can create forward-thrust.  It turns out, as well, that the presence of veins in the wings give them more rigidity, and therefore more lift for the effort expended. Lift was also enhanced by the undulating flight pattern of the butterfly.

The full research report is publicly available in the June issue of the journal Bioinspiration & Biomimetics.

The Journal Nature Continues Open Access Efforts

Last week, the journal Nature announced that seven more of their Publishing Group journals will give authors an open access option -- taking the total number of NPG journals with open access up to 25. By paying an author processing charge, authors can choose to make the article freely available to the public.

There has been a lot of discussion and debate in recent years about open access to scientific and scholarly material. On the 'pro' side, we have the argument that the results of any research funded with public tax dollars should be made freely accessible to anyone -- scientist or otherwise. Why should anyone who pays tax dollars need to then pay the thousands of dollars it might cost to purchase a subscription to leading journals? On the 'anti' side, we have the claim that making this material free and open to the public will take away necessary operating funds of many of these journals. Plus, there has been little discussion on the repercussions of what making this knowledge available to everyone might mean.

As educators and researchers, though, we know how important it is to have access to the most up-to-date information on what it happening in our fields. We can't "stand on the shoulders of giants" if we only have access to their knees. So, today, in addition to highlighting Nature's contribution, we'd like to show folks where they can find information on what journals currently offer open access options.

The Directory of Open Access Journals provides free, full text, quality controlled scholarly and scientific journals and should be your first stop. Then, check out some of these:

• Public Library of Science
• Notre Dame University
• Open-J Gate
• Directory of Open Access Scholarly Journals in Education
• Peer Reviewed Medical Journals
• Open Ethics Journal

Have other open access resources that you think are great? Let us know by commenting here, or on our Facebook page. For more on the open access discussion, read this article in Science.

Image from freedigitalphotos.net, courtesy of graur razvan ionut

Science Fiction Meets Real World -- The First "Synthetic" Cell

Image courtesy of Science/AAAS

It isn't quite the same as Adrien Brody and Sarah Polley's splicing of human and animal DNA to create a human-chimera, but scientists in in Rockville, Maryland have announced that they have created the very first "synthetic" cell. In today's issue of Science, Gibson et al. working at the J. Craig Venter Institute provide information on the research that has led to the creation of a chromosome from scratch, and ultimately to a self-replicating, live cell. The nucleotides of a common bacterium's DNA were digitalized using a computer, then assembled into sequence segments. Many of the sequences even carry a watermark with the names of the scientists involved in the project!

The research seems to have come straight out of Hollywood (ironically, Brody's film Splice is about to be released in theaters). While they have not created a new life form, the discovery is being heralded by some scientists as the greatest scientific discovery in the history of humankind, putting the team on a pedestal with Galileo and Descartes because this work could potentially act as a stepping stone to the creation of novel life forms, bio-fuels and medicines, among other things.

But, with great power comes great responsibility, and individuals concerned about the ethics and consequences inherent in such a discovery have voiced their opinions and concerns in Science's rival, the journal Nature. The eight opinions shared serve as an excellent resource for anyone interested in exploring controversy in science or ethics (for more on these, see our Visionlearning's Scientific Ethics module).

Tell us what you think? In light of this research, should the federal government set more detailed guidelines on what can and cannot be done in the laboratory? Is this potentially the eugenics of the 21st century? Where do we draw the line in manipulating DNA?

The Vine that Ate the South

Take a drive through parts of the southern US and you'll notice a bright green, ivy-like plant forming tents over many trees and telephone poles. It drapes itself from any possible hold, leaves vying for every ray of sunlight. In small bits it can be beautiful, but at the rate it's taking over the South it's downright scary.

The Kudzu vine (Pueraria montana) is an invasive species, originally from Asia, that was introduced to the southern US in the 1870s. In the mid 1900s, farmers and the Civilian Conservation Corps were encouraged to plant the vine wherever there was bare soil in an effort to reduce erosion. Unfortunately, like many introduced species (think starlings and zebra mussels) the kudzu vine was able to adapt to its new environment very quickly, sending out runners to establish new plants. (Click here to learn more about adaptation.) The result was that the vine began to quickly smother native species -- they can grow as much as 60 feet in one season, one foot per day!

New research published in PNAS shows that the kudzu not only chokes out other plants, but it's starting to choke out humans, as well. Like other legumes, kudzu and nitrogen-fixing bacteria in soil form symbiotic relationships. The bacteria help the plant to grow by producing ammonium; the plant gives the bacteria a nice, safe place to live. As the new research shows, however, the rate at which nitrogen is being fixed is problematic.

The journal Science explains: "The fast-growing legume fixes atmospheric nitrogen at a really high rate and the resulting increases in nitrogen cycling has triggered a dramatic increase in nitric oxide emissions from soils, according to a new paper in PNAS. Nitric oxide is a key precursor to ozone, and while this usefully blocks the sun’s harmful rays when it’s high in the atmosphere, it is an air pollutant that damages lungs and prevents plants from absorbing carbon dioxide when it occurs at the surface."

Are you or your students conducting research on invasive species? We would love to hear about it! Share your thoughts here, or on our Facebook page.

Click here for more information on nitrogen cycling.

Image by lowresolution via Flickr