Schlieren Flow Visualization, let the science flow
Many thanks to Koen De Paus for sharing this. I learned something new today. I had not heard of Schlieren flow visualization before.
#ScienceSunday
Originally shared by DaFreak
Casting Light on Sound to See its Shadow
“When light passes between areas of different air density, it bends. You’ve probably noticed the way distant pavement seems to shimmer on a hot day, or the way stars appear to twinkle. You’re seeing light that has been distorted as it passes through varying air densities, which are in turn created by varying temperatures and pressures.
In the mid-19th century, German physicist August Toepler invented a photography technique called Schlieren Flow Visualization to visually capture these changes in density. The setup is a bit hard to explain in words (watch the video above for a full explanation) but it allows scientists and engineers to see things that are normally invisible: the rising heat from a candle, the turbulence around an airplane wing, the plume of a sneeze.
It can also be used to see sound. Sound, after all, is just another change in air density — a traveling compression wave. A speaker pushes on the surrounding air, creating a wave that travels outward until it encounters the ear drum.”
Professor Rajini Rao is a tremendous role model along with Dr. Anandabi Joshee, Dr. Kei Okami, and Dr. Tabat M. Islambooly. If you don’t have Rajini circled, you are missing a lot.
Rajini’s post is very timely as I’ve been meaning to re-share Giselle Minoli’s post:
I think it’s best to visit the OP because the discussion is excellent and has many points that, unfortunately, don’t follow the re-share.
I think Dr.s Joshee, Okami, and Islambooly would be disappointed to find that, female physicians (after correcting for differences in specialties) make about $12,000 less than their male counterparts. As I said, we still have a ways to go.
Gender Differences in the Salaries of Physician Researchers posted by Adrienne Roehrich
Even in science, we have work to do. The study from PNAS reports that men and women scientist are biased towards hiring men and paying them more.
What can we do? For me, I strongly support programs that foster women in STEM such as Girlstart. I support equality at work and online. I support STEM Women on G+. Do you have other suggestions?
I’m pleased that G+ is, in general, very supportive of women in science and I have the pleasure of working with Rajini Rao Allison Sekuler Buddhini Samarasinghe Carissa Braun and Aubrey Francisco on ScienceSunday
Originally shared by Rajini Rao
On The Shoulders of Giants
♀ A sepia print of an Indian woman, a Japanese woman and a woman from Syria, dated 1885. What do they have in common? Extraordinarily, each was the first licensed female medical doctor in their country of origin. They were trained at the Women’s Medical College in Pennsylvania, the first of its kind in the country. This was a time before women had the right to vote. If they did attend college at all, it was at the risk of contracting “neuralgia, uterine disease, hysteria, and other derangements of the nervous system” (according to Harvard gynecologist Edward H. Clarke).
♀ An all-woman medical school was first proposed in 1846, supported by the Quakers and the feminist movement. Dr. Ellwood Harvey, one of the early teaching faculty, daringly smuggled out a slave, Ann Maria Weems, dressed as a male buggy driver, from right outside the White House. With his reward money, he bought his students a papier maché dissection mannequin. Eventually, poverty forced him to quit teaching, but he still helped out with odd jobs. What a magnificent man!
♀ Fate and fortune were to buffet Ms. Joshi’s life. Married at age 9 to a man 11 years older, her husband turned out to be surprisingly progressive. After she lost her first child at age 14, she vowed to render to her “poor suffering country women the true medical aid they so sadly stand in need of and which they would rather die than accept at the hands of a male physician”. She was first offered a scholarship by a missionary on condition that she converted to Christianity. When she demurred, a wealthy socialite from New Jersey stepped in and financed her education. She is believed to be the first Hindu woman to set foot on American soil. I didn’t arrive until 1983 😉
♀ Times were tough then. The fate of these three intrepid pioneers was a sad one. Joshi died of tuberculosis in India at the age of 21, without ever practicing. Fittingly, her husband sent her ashes back to America. Islambouli was not heard of again, likely because she was never allowed to practice in her home country. Although Okami rose to the position of head of gynecology at a Tokyo hospital, she resigned two years later when the Emperor of Japan refused to meet her because she was a woman.
♀ Times have changed. My own mother was married at the age of 13 to a man also 11 years her senior. My father recalls helping my mother with her geography homework in high school. She never did attend college, despite being a charismatic woman with quicksilver wit and efficiency. Little wonder then, when I was accepted into graduate school in the US, unmarried and 21 years young, my parents staunchly stood behind me against the dire predictions of friends and relatives (“She’ll come back with a yellow haired American!” “Haven’t you read Cosmopolitan magazine? They are all perverts there!”). Happily, I escaped perversion, earned my doctoral degree and even gained a supportive spouse of my own. In 2004, I became only the 103rd woman to be promoted to Professor in the 111-year history of the Johns Hopkins medical school, and the first in my department, the oldest Physiology department in the country. If I have seen further it is by standing on the shoulders of giants.
Hopefully, this should clear up many misconceptions on the scientific method, along with our favorite post on the definition of a theory (no, it’s never going to “graduate” into a Law!)http://goo.gl/4xqQIf
Fareed Zakaria explains some ideas behind conspiracy theories.
Science is a process guided by simple set of rules scientists follow to make sure that what they do actually works. We have learned over the past four centuries that these are the bare minimum common sense rules to follow. Anything less and you will make mistakes and mislead people into believing falsehoods. Cold hard experience has taught us this over the generations.
Too many people believe science is like some kind of religion, where people just hypothesize and decide that their hypotheses are true, and believe in these hypotheses dogmatically. Evolution and climate change have been specifically targeted by politicians who want people to believe this about science, and all of science suffers as a result of this misinformation. All of science suffers when more and more people misunderstand what it is.
Quote:
1. Make an Observation — “What is happening?”
An Observation is when you notice something in the world around you and decide you want to find out more about it.
2. Define the Question — “Why is this happening?”
Defining the question creates an idea that can be tested using a series of Experiments.
3. Form a Hypothesis — “I think this happens because…”
A Hypothesis is a statement that uses a few Observations, without any experimental evidence, to define why something happens.
4. Perform Experiments — “Let’s test my Hypothesis…”
An Experiment is a series of tests to see if your Hypothesis is correct or incorrect. For each test, record the data you discover.
5. Analyze the Data — “Was my Hypothesis right?”
Analyzing data takes what you found in your Experiments and compares it to your Hypothesis. If needed, perform another Experiment to gather better data.
6. Conclusion — “Experiments show my Hypothesis was…”
Forming a Conclusion presents the Experimental Data and explains how it supports or rejects the Hypothesis. Often, Scientists will take this Conclusion and perform other Experiments on it to discover new things.
(end quote)
7. Request Peer Review — “Did you get the same answer as me?”
Ask other scientists to perform the same Experiments you did to check your work and make sure you didn’t make mistakes, see if they come to the same Conclusion as you did. The more people who get the same answers as you, the more confidence everyone has that you are right.
(thanks to Earl Matthews for sharing this to my stream)
With recent outbreaks of measles, pertussis, and even polio across the United States, I think it’s time to revisit our laws about vaccination.
Refusing to vaccinate your children doesn’t simply put them at risk: it puts at risk everyone who, for medical reasons — extreme youth, old age, health, allergy — can’t be vaccinated, as well as everyone whose vaccinations have lost potency over time. Personal objections to vaccination, whether it be because of (unsubstantiated) fears of side effects or religious reasons, put everyone around you at risk of death or serious injury. This is a classic case where your right to swing your fists around ends at my nose: the individual liberty interest in allowing people to decide which medical procedures to undertake is outweighed by the safety and survival interest of those around you.
I believe that it is time to end all non-medical exemptions from critical vaccination requirements such as MMR, DTaP, and polio — for epidemic diseases which kill and maim by the thousands when our immunity, as a population, is compromised.
My preference would be to treat this as a criminal matter: to fail to do this amounts to reckless endangerment. (Public endangerment, that is, not simply endangerment of a minor) More important, however, is the prevention of harm from people who do this: in particular, individuals unvaccinated without medical reason should be barred from all public accommodations where their presence could put other lives at risk, including schools, parks, pools, and transit.
Such a barring would, of course, have a nearly-catastrophic effect on the life of anyone not living in a remote, rural area; it essentially would reduce a person to second-class citizenship. However, I believe that this is a reasonable accommodation of the public safety interest, as by definition it is something which the person can circumvent by simply not putting the general public in danger by their mere presence.
There are times when I’m willing to be fairly forgiving. When the rightness of a course of action is unclear, I’m generally in favor of letting said action be a matter of individual conscience. However, when an individual’s actions put those around them at risk, this is exactly what we have laws for. You have no more personal right to expose others to deadly diseases than you do to fire a gun blindly into the street.
Like many of the science hype articles in the media, the picture below is misleading. In Buddhini Samarasinghe’s post about cutting through the hype about “exploding” cancer cells: “Exploding Cancer Cells” Explained (http://goo.gl/kZMpVM), we talked about the vehicle control, dimethyl sulfoxide or DMSO. The vehicles below are dangerous but we aren’t talking about that kind of vehicle.
∇ What is a vehicle?
So in biomedical research, what is a vehicle? The American Heritage Medical Dictionary defines vehicle as a substance of no therapeutic value that is used to convey an active medicine for administration. So a drug in a liquid form may use saline (salt water) or a liquid buffer as a vehicle, i.e., the drug is dissolved or mixed with the vehicle. This maybe necessary to get the dose right, i.e., dilute the drug/compound. It maybe necessary to use a vehicle because the compound needs assistance to be transported depending on the route of administration. So for skin creams (transdermal drug delivery) a lotion-like vehicle might be used.
∇ Vehicle Control
No I’m not talking about Automatic Brake Systems or sway-bars. Vehicle controls in biomedical research means a group of test subjects that are given the vehicle alone. It’s like a placebo group but is more specific than that. You’ve probably heard of sugar pills being used for the placebo effect. A vehicle control tests to confirm that the vehicle has no effect on its own. Imagine if you are testing a new drug without a vehicle control group and all of the subjects get sick. You don’t know if it is due to the drug or the vehicle. Similarly, what if all of the subjects show improvement but there is no vehicle group to test to demonstrate that it was the drug alone. In the study that Buddhini Samarasinghe discusses, DMSO was the vehicle.
∇ Dimethyl Sulfoxide (DMSO)
DMSO is often used as a vehicle because a lot of drugs are not water soluble and but are soluble in DMSO. If you want to get a drug into the blood stream, it’s best if it is water soluble. However, some drugs are hydrophobic (they don’t like water but they like oil). If a drug is promising enough, you don’t let hydrophobicity stop you. The LD50 of DMSO is 13.4–15.5 g/kg (12.2–14.1 ml/kg). What does that mean? The LD50 is the dose at which half of the subjects die. LD stands for Lethal Dose. Unfortunately the authors don’t say what dose they used for the vehicle. We don’t know if the vehicle could have had an effect alone. We do know that DMSO can have effects even at low doses.
For example Julien et al found that DMSO had an effect on some enzymes they were interested in for Alzheimer’s disease. They state: These data should caution researchers working with DMSO as it can induce artifactual results both in vivo and in vitro. Galvao et al reported that even low doses of DMSO had toxicity. Finally, Hanslick et al discuss DMSO producing apoptosis in the central nervous system. If you have been paying attention to Buddhini’s Hallmark of Cancer series, you’ll know that apoptosis is programmed cell death.
A couple more comments about the “exploding” cancer cell paper. In one part they show that tumor volume is reduced with treatment and not with DMSO. Tumor volume alone, can be misleading. There are drugs that kill the tumor but the tumor does not shrink, at least not right away. So if the tumor stays the same size, the drug did not necessarily fail. You need functional imaging to show that the tumor is still viable (regardless of size) or the tumor is dying. Also some drugs can make the tumor swell with fluid but the tumor is nevertheless dying. That is another example where tumor volume alone, is misleading. The second comment about the paper is that the live cell imaging experiments were done with an Operetta system. I recommend you check out the video Watch Operetta Product Overview Video (http://goo.gl/FUyKLu) It’s on the right side.
A couple of my favorite quotes are applicable here:
Alle Ding’ sind Gift, und nichts ohn’ Gift; allein die Dosis macht, daß ein Ding kein Gift ist.
“All things are poison, and nothing is without poison; only the dose permits something not to be poisonous.” Paracelsus
The only real difference between medicine and poison is the dose….and intent. Oscar G. Hernandez, MD
∇ References:
LD50 of 13.4–15.5 g/kg (12.2–14.1 ml/kg)
Caujolle F, Caujolle D, H B, Calvet MM (1964) [Toxicity and pharmacological aptitudes of dimethylsulfoxide]. C R Hebd Seances Acad Sci 258: 2224–2226.
Farrant J (1964) Pharmacological actions and toxicity of dimethyl sulphoxide and other compounds which protect smooth muscle during freezing and thawing. J Pharm Pharmacol 16: 472–483.
I dig dragonflies. They have gorgeous colors and they just look awesome. Did you know that their 30,000 lens eyes can also detect ultraviolet light? Because dragonflies and their cousins damselflies don’t have glomeruli, it was thought that they can’t smell. Glomeruli are a cluster of nerve endings near the surface of the olfactory bulb (which is responsible for olfaction, aka smelling) in the brain. I’ve got a cool MRI of a rabbit brain that shows how big the olfactory bulbs are in a rabbit. I should dig that up. Back to the dragonfly, it was recently discovered that they have tiny bulbs in pits on their antennae that may be related to smell. As if dragonflies smelling from their antennae isn’t cool enough, these pits were found using an electron microscope. To test their theory, they used a wind tunnel and dragonfly bait, aka fruit flies. You can read more here:
Dragonflies Lack ‘Smell Center,’ but Can Still Smell
This is another example of how man’s best friend can work with humans to help other animals. I’m imagining Peter Lindelauf and Luna going through the woods and finding bear scat. I wonder if these dogs could help Erin Kane in her search for monkey scat.
Happy #FidoFriday and remember it’s #ScienceEveryday
Originally shared by KQED SCIENCE
Dog Detectives: A Nose for Conservation
“Around the world canines are being enlisted to track rare wildlife, sleuth out invasive species, and detect otherwise imperceptible changes that could harm wilderness areas and watersheds. But are these canines really providing significant support to conservation efforts, or is it just another excuse to bring your dog to work?”
Happy Pi Day courtesy of Richard Green. I wonder what Ramanujan would have accomplished, had he lived longer than 32 years.
Originally shared by Richard Green
Happy Pi Day!
The number pi or π (approximately 3.14159265) is well known as the ratio of the circumference of a circle to its diameter. Although π is an irrational number, meaning that it cannot be expressed exactly as a fraction, it is possible to express the number as an infinite series.
One of the simplest such series is π = 4 – (4/3) + (4/5) – (4/7) + (4/9) – (4/11)… The standard techniques of calculus can be used to prove that this series converges to π. Unfortunately, the convergence is very slow, meaning that one needs to write down a large number of terms to approximate π with any degree of accuracy.
The Indian mathematician Srinivasa Ramanujan (1887-1920) found some approximations to π that are much better than the above series. The formula for the infinite series at the bottom of the picture is due to Ramanujan. It converges so quickly that each successive term in the series computes a further eight decimal places of π. To give you some idea of how accurate the formula is, the approximation given by just one term is 9801/(sqrt(8)x1103), which works out as about 3.14159273001. This is accurate to eight significant figures, and has the first six decimal places correct!
This is a very impressive approximation from a mathematician who worked before the era of computers. Perhaps not surprisingly, Ramanujan’s contemporaries were curious about where he got his ideas. The answer is quite interesting: while dreaming, he received visions of scrolls of complex mathematical content from his family goddess, Mahalakshmi of Namakkal.
Although he died at the age of 32, Ramanujan left behind a large number of mathematical results, and some of the best modern methods for computing π are based on his work. Ramanujan did not write up proofs for many of his results, although most of them turned out to be both correct and original. However, he left behind four famous notebooks of rough ideas, one of which was lost until 1976. These notebooks have inspired many papers by later mathematicians attempting to prove Ramanujan’s results.
