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Buddhini Samarasinghe

Hangouts On Air  - 
Processed meat and Cancer: What is the Risk?

Yesterday I hosted a Hangout with two scientists to talk about the links between diet and cancer, on the back of the "omg bacon gives you cancer" stories that broke out a few weeks ago. As part of my job as a science communicator at CRUK, I get access to researchers who study this, so I was very pleased to chat with Dr Kathryn Bradbury, a nutritional epidemiologist, and Professor Owen Sansom, a molecular biologist. It was a good mix of research interests because we were able to approach this question from a population/clinical angle, but then also dive into the mechanism behind what we see, i.e. how exactly does red and processed meat increase cancer risk. You can watch the full video at Joining me was my colleague Dr Kat Arney, who co-hosts these cancer Hangouts with me. 

First we discussed how we find out what things in the diet are linked to cancer - Kathryn explained how we design studies looking at hundreds of thousands of people from the general population. We ask them questions about their diet and lifestyle, and then we follow them up over many years to see who develops cancer. Then we look back and see what effect their diets had on their cancer development, for example did vegetarians get less cancer than those who ate lots of red and processed meat. Having large-scale population based studies like this is the only way we can gather evidence for the risk factors for cancer; lots of people mean better statistical analyses, which means the data is more rigorous, rather than the anecdotal "oh my neighbour drank a miracle kale juice cleanser every day and he never got cancer" theories. 

Owen talked about the mechanisms for cancer development, particularly bowel cancer, and how it is linked to the molecules found in red and processed meat. The cells lining our gut get completely replaced every 3-4 days, so they are cells with a high rate of cell division. These cells are also exposed to cancer-causing chemicals (i.e. carcinogens) from the food we eat, depending on our diet. With red and processed meat, eating a lot of it means that the gut cells are also exposed to a lot of the carcinogens found in them. For example red and processed meats have a lot of nitroso products, and these can be carcinogenic. How exactly does that work? These chemicals cause mutations to the DNA in the cells lining the gut. Owen also talked about how it can cause more mutations in key tumour-suppressor genes (i.e. genes that normally suppress cancer, but when these genes are mutated it leads to cancer - I discussed one such pathway here Haem iron from red meat is also a culprit because it has shown to cause DNA damage. Intriguingly, Owen also brought up how the bacterial population in our gut (i.e. our microbiome) can change depending on what we eat, which in turn can have an impact on whether the cells lining our gut can end up with mutations that can lead to cancer. 

Finally we finished up by talking about cancer prevention. We know that 4 in 9 cancers are linked to preventable causes, so what are the things we can do to lower our cancer risk? The answers were unsurprising; give up smoking (if you smoke), reduce instances of sun-burn, eat a well-balanced diet with moderate amounts of red and processed meat (i.e. bacon with every meal every day is probably a bad idea), along with physical activity. 

Of course this is much easier said than done, because people often want quick-fix miracle cures/pills/whatever that lets them keep living unhealthy lives without feeling bad for it. Unfortunately there are no such shortcuts that are scientifically valid. Listening to Kathryn and Owen discuss the cancer risk from red and processed meat, along with the mechanistic explanation of 'how' was incredibly useful, and I hope you enjoy watching this Hangout :)
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Physics Forums

Science Bytes (Memes, Cartoons, Images)  - 
The space chimp holding a newspaper after his trip to space in 1961
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Many animals including monkeys, dogs, mice died during space flights. 
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Ne GaR

Science Bytes (Memes, Cartoons, Images)  - 
Just for fun :-D
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Sample vial takes sample vial....they kinda are like a pawn in the scale of things
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Amna Rizvi

Science News (Pop Sci)  - 
The process is called Femto-Photography

A brand new camera developed at Massachusetts Institute of Technology can photograph a trillion frames per second. Compare that with a conventional film camera which takes a mere 24. This new development in photographic technology has given scientists the power to photograph the motion of the fastest thing in the Universe, light. In the video below, you’ll see experimental footage of light photons traveling at approximately 965 million-kilometers-per-hour (that’s roughly 600 million mph) through water. The actual event occurred in a mere nano second, but the camera has the ability to slow it all the way down to twenty seconds. For some perspective, according to New York Times author, John Markoff, “If a bullet had been tracked in the identical fashion moving through the same fluid, the ensuing film would last 3 years.”
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what a bluff!
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Massimo Luciani

Science News (Pop Sci)  - 
An article published in the journal "Nature Physics" describes the results obtained with a series of simulations conducted using supercomputers at the Department of Energy of the USA's Oak Ridge National Laboratory (ORNL). The object of these sophisticated simulations were proteins to understand their motion, a key element in the functional, structural and regulatory roles they have in living organisms.
A blog about technologies, sports, books and other stuff, especially science fiction
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+Michael Gonzalez bioinformatics is an expanding field, maybe computer science applied to physics too.
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Rajini Rao

Life  - 
Engineered mosquitoes that could rapidly spread in the wild and eradicate the malarial parasite have been made. Here is the question: Should we use Gene Drive engineered mosquitoes to fight Malaria?  Read the post and then cast your vote! 
Gene Drives: Green Signal or Back Seat? 

What is the deadliest animal on earth? If you're thinking of the great white shark or a venomous snake, you could be wrong. Counting human deaths, it is the innocently named (Spanish for "little fly") mosquito. Millions, mostly children in third world countries, are killed or sickened each year by malaria, dengue, yellow fever and encephalitis caused by parasites and viruses that are transmitted by mosquito bites. This happens despite billions of dollars spent, years of research and potential cures ranging from vaccines and drugs to public health management. 

Stop or Go, that is the Question: Imagine if the mosquito could kill the parasite before it has the chance to spread to its human victims. For example, the mosquito could be engineered to make antibodies against Plasmodium, killing the parasite soon after it enters the mosquito after a blood meal. Just like a vaccination, nearly all mosquitoes would need to carry this new trait to be effective. There is a way to do this and it is not a new idea. What used to be theory, however, has just become a reality. A new paper published in the journal PNAS has now changed the question from Can we do this? to Should we do this?

What are Gene Drives?: Normally, the chance that any gene trait is passed from parent to offspring is 50%, since only one of a chromosome pair is inherited from that parent. But some selfish genes can copy themselves so that both chromosomes carry the trait, which now affects 100% offspring. A gene drive consists of DNA sequences that provides the technical ability to do this. With the new CRISPR/Cas9 tool that precisely cuts and inserts any gene of interest, the gene drive has become a reality. 

Can Gene Drives work on Humans? Gene drives work best in fast reproducing species, like mosquitoes, that can be released in large numbers. For this reason, they are not going to be effective in spreading inadvertently through humans, or even commercial crops and animals which are bred by controlled processes like artificial pollination and insemination.  

Gene Drives are Natural: For example, a gene called P element swept through all fruit flies in the wild, but is not found in lab strains that were isolated before it spread. 

Gene Drives can be Reversed: For each gene drive that spreads a trait, a reverse gene drive can undo the genetic changes in the original strain. Such reversal drives should be tested in advance, and could be released to stop the spread of any unintended consequences.

What else can Gene Drives do? Besides targeting mosquitoes, gene drives could be used to eradicate invasive species, or reverse resistance to herbicides and pesticides. 

Take the Poll: A public conversation based on sound scientific information, weighing pros and cons, must be the starting point for developing policy. Engineered mosquitoes that could rapidly spread in the wild and eradicate the malarial parasite have been made. Here is the question: Should we use Gene Drive engineered mosquitoes to fight Malaria? 

FAQ on Gene Drives:
Image: Matt Panuska
Pop Science Read:
Advanced Read:
330 votes  -  votes visible to Public
Yes, release the engineered mozzies!
No, there may be unintended consequences
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Mathew Emmanuel Pineda

Science News (Pop Sci)  - 
This PRELIMINARY study suggests that we might be communicating our positive or negative emotion through the smell of our sweat.
Positive or negative emotions produce chemosignals and we might be communicating them through the smell of our sweat.
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+Akinola Emmanuel I think "smell" in the sense of chemosignals. Although we might not be actually smelling it, our olfactory sense can pick 'em up. We share the same name by the way! Haha :)
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Guneet Bhatia

Science News (Pop Sci)  - 
The set of three robots created by HIT Robot Group in China and recently presented at the World Robot Conference can scrutinize an area to detect dangerous materials, move or diffuse a bomb and launch an attack against the target.
A Chinese firm has introduced an anti-terror robot in the World Robot Conference, which has a capability to launch grenades and carry rifles.
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Esin Murat

Science News (Pop Sci)  - 
15 minutes can save you 15% or more on sleep insurance.

Check out this cool interactive wheel!:
Napping benefits a person in so many ways. Here's how to get started with this healthy habit.
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+Jim Sparky It is one too, experience confirmed ;).
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Version Daily

Science News (Pop Sci)  - 
The results, however, did not reveal weight gain or any signs of insulin resistance. Nonetheless, it revealed early skeletal muscle adaptations coming from short-term high-fat diet.
A high-fat diet for five days leaves muscle unable to oxidize glucose properly, thus creating metabolic disruptions in the body.
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I noticed that the two specific examples mentioned are not only high in fat, but high in carbs, so I can't help but wonder if the effects are strictly from the fats.
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About this community

Science on Google+ is a community moderated by scientists, for all people interested in science, both professionals and the general public. The primary goal of this community is to bring real scientists to the public, for science outreach. A secondary and long-term goal is to create an environment that fosters interdisciplinary collaborations; thus, enabling and promoting cloud collaboration between scientists. See Guidelines and Rules section for additional details.
Exploring Multiple Sclerosis
      by +Cheryl Ann MacDonald 

✽   Multiple Sclerosis is a fluctuating, at times disabling illness of the central nervous system that disturbs the stream of information between the body and the brain. Although very difficult to determine, this disease affects approximately 2.3 million people, globally.

✽   Multiple Sclerosis (MS) is an advancing, neurological disorder in which the protective layers that wrap around the nerve fibers (myelin sheaths) are destroyed in sectional chunks throughout the central nervous system. Controlled by the site of the demyelinated patches within the central nervous system, signs and symptoms vary enormously. 

✽   Psychological effects of Multiple Sclerosis
         Generalized anxiety and irritability
         Uncontrollable crying and laughing
         Stress reactions to everyday life situations
         Unusual behaviors such as sexual impulsivity
         Mood Swings often changing in frequency            
         Grieving for physical and emotional losses        
         Symptoms of depression 

This is an in depth, long read containing the Biological, Psychological and Sociological effects of Multiple Sclerosis. At the end of the article there are a few tips for patients, family & loved ones. For the entire read

Images throughout the text are from +Eve Aebi  collections and please thank her for allowing me to reproduce.

Take care all
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Thanks for the comprehensive review in the link, +Cheryl Ann MacDonald . 
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Habitable Exoplanets

Science News (Pop Sci)  - 
"We need to become a spacefaring society and eventually we need to move far beyond Mars — not only from our own solar system, but into other solar systems within this galaxy and other solar systems in other galaxies."  —Stephen Petranek
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Jonah Miller

​​​Physical  - 
The Three "Classical" Tests of General Relativity

Last Wednesday was general relativity's 100th birthday. In celebration, here are three "classical" experiments that helped convince the world that Einstein's crazy idea was right.
Classical Tests of General Relativity

Last Wednesday, November 25, was the 100 year anniversary of general relativity. It was the precise day that Einstein presented his field equations, shown in figure 1, to the world. In celebration of this anniversary, today I present to you some of the early triumphs of general relativity, classical predictions of the theory that have been precisely tested and where theory has exquisitely matched experiment. This is the sixth instalment of my howgrworks series (see: Let’s get started.

(Those interested can read this post in blog form here:

The Perihelion of Mercury

Before Einstein, we believed that the motion of planets in the solar system were governed by Kepler’s laws of planetary motion. These can be derived from Newton’s laws of motion and universal gravitation, but Kepler discovered them before Newton, through the power of careful observation.

Kepler’s laws are very good. To an extremely good approximation, they do describe the motion of a single planet orbiting the sun. They tell us that the orbit of a planet around the sun has the shape of an ellipse, like that shown in figure 2. The point where the planet is closes to the sun is called the perihelion of the planet.

But planets don’t actually follow perfect, closed, elliptical orbits. The ellipse slowly rotates, or precesses over the course of time, meaning that the perihelion of the planet moves over time, as shown in figure 3.

This precession is caused by a number of factors. The gravitational influence of other planets, for instance, contributes. Indeed, for most planets, the gravity of the rest of the rest of the solar system adequately explains the precession. But there’s one planet where this isn’t the case: Mercury. If you work out the numbers, the precession of Mercury’s orbit is too big to be explained only by the gravitational effects of the other planets.

For several decades, the perihelion of Mercury was a mystery. People hypothesized that there was a tenth planet (or dwarf planet) in the solar system closer to the sun than Mercury, called Vulcan. The planet Vulcan turns out not to exist, but its legacy lives on, as shown in figure 4.

When Einstein developed general relativity, he knew about the mystery of the perihelion of Mercury, and he believed he had the answer. Einstein worked out some of the corrections to a Keplerian orbit due to general relativity, and found they perfectly predicted Mercury’s perihelion.

General relativity was off to a great start!

The Deflection of Light

But Einstein wasn’t content with explaining observations we’d already made. He wanted to make a prediction. Ever since Newton proposed his law of universal gravitation, people have wondered if gravity should effect the path of a beam of light. In 1784, the brilliant Henry Cavendish calculated the gravitational pull of a planet on a small particle moving at the speed of light. At the time, people didn’t know that photons are massless, but it turns out not to matter. The change in the path is independent of the mass of the particle.

General relativity also predicts that gravity should bend light, but for very different reasons. In general relativity, a massive object distorts spacetime itself, and light simply takes the straightest path. You have to work through the numbers, but if you do, you discover that this means light bends twice as much in general relativity as in  Newtonian gravity.

But how to test this prediction? Einstein proposed that we could use the sun itself. The sun should bend the path of starlight from the stars behind it. This is an example of gravitational lensing, which I’ve discussed before (see: Of course, usually the light from the sun masks any starlight one might wish to observe. But during a total solar eclipse, like the one shown in figure 5, the moon completely obscures the sun, and the stars should be visible.

After hearing Einstein’s prediction, Sir Arthur Standley Eddington lobbied strongly for an expedition to test it. Eddington saw the expedition both as an exciting scientific opportunity and as a way to heal the wounds of the first world war, which was still raging when he began lobbying for the expedition. After a long legal battle, Eddington avoided the draft and was granted a grant of 1000 pounds sterling for the expedition. As gravitational physicist Clifford Will writes in his article on the event (see:

The decision reeks of irony: a British government permitted a pacifist scientist to avoid wartime military duty so that he could go off and try to verify a theory produced by an enemy scientist.

But in March 1919, Eddington set sail for an island off the coast of Guinea and his collaborator, Andrew Claude de la Cherois Crommellin sailed to northern Brazil. Each expedition aimed to observe the deflection of light in 1919 total solar eclipse. This is a very difficult measurement to make and, due to inclement weather, the Crommelin team was unable  to make a definitive measurement. The Eddington team, however, was able to make a definitive measurement, one that confirmed Einstein!

Eddington’s result was widely publicized, and it sky-rocketed Einstein to fame. In 1919, as now, general relativity captured the public’s imagination. After Eddington announced his result, the Illustrated London News ran a major spread, describing the experiment, shown in figure 6.

In science, it is not enough to explain observed phenomena, one must make a new, testable prediction. And Einstein’s prediction of the bending of light did just that. It was this victory that convinced the scientific community, and the world, that general relativity was right.

Gravitational Redshift

At the core of Einstein’s theory is the idea of gravitational redshift. If you take a beam of light at the surface of the earth, and somehow transport it up to the top of a tower, it will appear redder in colour than it did at the surface. This is because spacetime is stretching out as we move away from the surface and the wavelength of the light is stretching out with it. I’ve described this in great detail before (See:

It turns out that we can actually experimentally test this prediction! In 1959, Robert Pound and Glen Rebka used atomic nuclei in a crystal lattice to measure the wavelength of a beam of x-ray light, which they transported from the top of a tower, shown in figure 7 in a Harvard physics building to the basement, 74 feet below. This is the now famous Pound-Rebka experiment.

Of course, even with an extremely precise understanding of the light and the atomic transitions, this experiment would be impossible without some clever tricks. The experiment deserves an article all by itself. So for now, I will point you to this wonderful article in Physical Review. Suffice to say Pound and Rebka’s experiment confirmed Einstein’s predictions in exquisite detail:

And Many More…!

There are many more tests of general relativity, and I plan to tell you about them in another post. So Stay tuned!

Related Reading

This is the sixth part of my series on general relativity. Here are the first parts:

1. In Galileo Almost Discovered General Relativity, I describe the equivalence principle, which is the foundational idea behind general relativity:

2. In General Relativity is the Dynamics of Distance, I describe how the equivalence principle leads to a distortion of the way we measure distances and durations:

3. In General Relativity is the Curvature of Spacetime, I describe how a distortion in distance leads to curvature:

4. In Distance Ripples, I explain how gravitational waves work:

5. In Our Local Spacetime, I describe a visualization of spacetime near the Earth:

Further Reading

I’m far from the first person to write about this.

1. +Ethan Siegel  has a great article on the Perihelion of Mercury and the bending of light:

2. +Brian Koberlein  has an excellent article on Eddington's measurement during the total solar eclipse:


For the brave or very interested, here peer-reviewed articles of interest. You will notice a preponderance of articles by Clifford Will. This is no accident, as he’s the world’s foremost expert on experimental tests of general relativity. (He’s also Canadian! Go Canada!)

1. An excellent resource on experimental tests of general relativity, and the mathematical framework for investigating those experiments, is “The Confrontation of General Relativity with Experiment,” by Clifford Will. It’s a very technical work, but it comprehensively reviews our certainty of the correctness of general relativity as of 2006:

2. This article carefully calculates the non-relativistic contributions to the precession of Mercury’s orbit:

3. In this article, Clifford Will discusses the derivation of the bending of light in Newtonian gravity:

4. In honour of the centennial anniversary of general relativity, Clifford Will wrote a review article of the 1919 measurement of the deflection of light:

5. You can read the original paper by Eddington, published by the Royal Society of London, on the eclipse measurement:

6. There are many other measurements of the deflection of light. For example, we’ve observed the bending of light due to Jupiter’s gravity.;

7. Physical Review published an absolutely wonderful article on the Pound-Rebka experiment. You should all read it:
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Version Daily

Science News (Pop Sci)  - 
Renowned biologist and geneticist Dr. Cynthia Kenyon has been revolutionising the science behind aging. One of her biggest breakthroughs was figuring out that carbohydrate intake is a universal hormonal control for aging. So far, this theoretical link between aging and carbohydrates has proved true for worms, mice, rats, and monkeys.
Several scientists are establishing a link between aging and carbohydrates. The secret to aging slowly might involve ditching carbs.
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The articles referenced by this puff piece are pure speculation. The first article speculates that results of putting worms in a glucose solution and their hormonal reactions to that might have some relation to human ageing. The second speculates that consuming carbohydrates may contribute to Alzheimer's, by carbohydrates first causing insulin resistance and diabetes. However, carbohydrates have not been shown to do that yet. In fact, a low fat high carbohydrate diet was shown empirically to be a cure for insulin resistance and diabetes by Dr Walter Kempner, successfully with many patients for many years beginning in 1939 at Duke University. Which do you prefer: evidence based medicine and bread without butter, or pure speculation and butter without bread?
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Sam Canyon

Science Outreach  - 
We know that every object (as small as a rock all the way to as big as an entire galaxy) is moving around something, like all the objects in the milky way are moving around a massive blackhole in the middle of our galaxy

Now where are all the galaxies in the universe moving to ?
They should move around something

What is that something ? 
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+Joe Grundy and +Johnathan Gross already offer excellent answers here.

To be more concrete. Many galaxies are part of galaxy clusters. They are all gravitationally bound to each other, but they do not orbit each other. The nearest cluster to us is the Virgo cluster:

On the largest scales, galaxies and galaxy clusters are all moving away from each other as the universe expands. But if you take that into account, they're moving in essentially random directions.
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Habitable Exoplanets

Science Bytes (Memes, Cartoons, Images)  - 
The Earth isn't an ordinary generic planet. The processes that created an Earth suitable for modern are unique and surprising.
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We don't know they're unique.
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Science on Google+

Hangouts On Air  - 
Live in 30 mins - come join us as we talk about the links between processed meat and cancer, and how diet can affect cancer risk. 
We've all read the headlines about the link between processed meat link and cancer. But what exactly is the risk, and should we give up bacon and burgers? Is it really as bad as smoking? What is the underlying mechanism behind the increased risk of developing cancer? Join us for a +Science on Google+ and +Cancer Research UK  Hangout on Air as we speak to Dr Kathryn Bradbury and Professor Owen Sansom about this story. 

Kathryn is a nutritional epidemiologist at the University of Oxford who studies the links between diet and cancer. Owen is a molecular biologist at the Cancer Research UK Beatson Institute in Glasgow, who is investigating the cell signalling pathways that are activated in colon cancer. 

This HOA will be hosted by Dr +Buddhini Samarasinghe and Dr +Kat Arney  . You can tune in on Friday November 27th at 4 PM UK time. The hangout will also be available for viewing on our YouTube channel ( after the event.
This Hangout On Air is hosted by Science on Google+. The live video broadcast will begin soon.
Processed Meat and Cancer: What is the risk?
Fri, November 27, 11:00 AM
Hangouts On Air - Broadcast for free

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Jason Davison

​​​​​​​​​Earth  - 
California Basin Model

Modeling California's Water Resources. 
California Basin Model

California is pumping groundwater at an uncontrollable rate. Currently, the California basin receives approximately 8,000 cubic meters per second of water over the entire domain. However, the state relies on groundwater resources and takes about 1,300 cubic meters per second. This ratio (approximately 15%) results in a drastic decrease of the water table. 

The video shown below is a simulation of the California Basin using HydroGeoSphere. The model takes into account surface water, groundwater, evapotranspiration, precipitation, and groundwater pumping. On the right hand side, the plot shows the depth to the groundwater table. On the left side, the plot show the change in water table from pre-development levels. 

The key point to pull from this figure is that the southern arid region has less precipitation, which causes a stronger and faster decrease in groundwater levels. 

#Groundwater   #Drought   #California  
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+Rexor Lexor Nestle's pumping rates are so insignificant on this scale they don't matter. My model includes all of the water withdrawals monitored by the state. The vast majority of water removed is for agriculture.
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Sam Canyon

Science Outreach  - 
My question might sound crazy, but i'm nit an expert

How do we know that there is no planet on the other side of the sun that is maybe rotating at the same speed that earth does
So it it will never come around sun so we can see it ?
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detection is not only seeing. there are other ways such as perturbations due to gravity etc.
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New research published in the journal Science shows that coordinated international reductions of greenhouse gases over time have the potential to reduce the highest levels of global warming. Read more about this study at
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...somehow 'pledges' don't make me feel better!
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