Now on Nature Network

In hope of bringing more readers to this blog, I decided to move it to Nature Network. From now on my posts will be published here. Follow me!

Of mice and parachutes

This Guardian piece, tucked away in the Education section, has such an eye-catching title that I decided I was going to blog about it even before I read the article. Seriously, compliments to the editor (or the author?): “Why dead mice need parachutes in the forest”. The facts reported in the piece are even funnier than the title might suggest.

Why would dead mice need parachutes, you may ask? The answer is, possibly, odder than the question: to deliver poison to tree snakes. Guam is an island in the Pacific Ocean, an unincorporated territory of the United States, which is infested by brown tree snakes (Boiga irregularis). They are thought to have been a stowaway on a US military cargo back in the days of World War II. Having no natural predators on Guam, they quickly became numerous and troublesome. They prey on domesticated birds, they occasionally cause power outages by climbing on transmission wires, and they even bite small children mildly affecting them with their venom. Besides being a nuisance to humans, they have also eaten to near extinction some native birds and lizards posing a serious ecological threat to the island.

The solution to this problem passes for reducing the tree snake population, and this is how the mice and their parachutes get into this story. The principle is simple: snakes that eat poisoned mice die. But you can't simply drop poisoned mice on Guam rain forests because other species, such as the coconut crab (a protected species), can become victims of this non-targeted approach to the problem. The solution? Parachutes. If you parachute the mice from an aircraft, they get entangled in the forest canopy where only the tree snakes can reach them!

The funniest thing is that this is not even what the Guardian article and the scientific paper it refers to are about. The key issue of the scientific study is the parachute itself.  About 10 years ago people tried plastic and cornstarch parachutes but the former take long to degrade and the latter dissolve too quickly in the rain dropping the mice to the ground. It is important to test different materials and types of parachute to make sure the mice get entangled in the forest canopy for long enough for the snakes to eat them, but do not pose an environmental problem. This is what scientists did.

Scientists attached various parachute-like objects – the list included paper plates, paper cups and paper streamers, amongst others – to dead mice and then thrown them from a US Navy helicopter into the forest. They also radio-equipped the rodents to track their fall. The results of the study indicate (you'll be glad to know) that all of the easily degradable materials tested work well. However, certain parachutes, such as the paper cups and paper plates, are not practical because they need to be secured to the dead mice with threads, which is a time-consuming process. The best method appears to be attaching paper streamers to cardboard which is then glued to one of the mouse's rear legs.

I know this is a serious and environmentally conscious scientific study. Yet, I cannot help laughing every time I picture the face of that US Navy pilot looking at the crazy people gluing stuff to dead mice before throwing them out of his chopper: “WTF!?”

photo: The Kids Window

Yeah right, as if space had weather

Well, actually, it does. Space weather was in fact what was keeping me busy until yesterday as I was invited to co-write an article about it. It is an interesting topic, worth blogging about, so if you are curious and would like to know more about the Sun and its influence on Earth, read on.

You've probably heard about Auroras or Northern Lights, or are even lucky enough to have seen one of these events. They are proof positive of the existence of some sort of weather in space. The term “space weather” refers to changes in the near-Earth space environment which are driven by the Sun. On a calm day, only a breeze of radiation and energetic particles – the solar wind – flows from our star. Sometimes particles from this wind stream into the Earth and interact with the gas in the planet's atmosphere. These interactions release particles of light causing Auroras.

photo: Wikimedia Commons

But not all days are calm and the Northern Lights are by far the least threatening effect of space weather. Trouble starts when our very active star decides to rebel and begins to emit large amounts of energy, not to mention electrically charged material into space. That's when you get the space weather equivalent of hurricanes.

The Sun is made out of a material called plasma. Plasma is the fourth state of matter: a solid can be heated up to become liquid, a steaming liquid becomes a gas, and a hot enough gas transforms into plasma. This happens because the atoms that form the gas are separated into their constituents, electrons and nuclei. It is of this, electrically charged, material that the Sun is composed.

In the solar interior, plasma is in constant motion. If you recall your physics lessons from high school you may remember that moving electric charges generate magnetic fields. In fact, the Sun is a ball of plasma with tangled magnetic field lines breaching through its surface. One of the interesting things about magnetic fields is that they can store a lot of energy. Every now and then the tangled lines of the magnetic field break and the energy they store bursts into space. These explosions are what solar physicists call “solar flares” – the storms of space weather.

It gets worse. Sometimes the magnetic field lines break so violently that they drag along some of the solar plasma. In this case, a coronal mass ejection (CME), the equivalent of a hurricane, occurs. CMEs cause the most damage when they are directed towards the Earth. When they hit, the electrically charged material and energetic particles of the solar wind and solar plasma surge into the Earth's atmosphere and surface. While this can cause brighter auroras, the more beautiful Northern Lights come with a price. CMEs can be harmful to astronauts and even airline crews and passengers. They can also affect satellites, interfere with communications and cause power blackouts.

Fortunately, most days are calm when it comes to space weather. Terrestrial storms and hurricanes are much more likely to cause damage than solar flares and CMEs. But the weather can always affect you. Even if it's in space.

How would you dance your PhD?

Work is keeping me busier than usual this week so this will be a brief post. I've decided to keep with the dance theme to let you know about an incredibly original idea I read about today. I've seen science being communicated in the form of text, diagrams, video and photography but this is a first. Dance your PhD is a contest that aims to get anyone with a science-related PhD, or studying to get one, to explain what their thesis is about through dance. (It definitely got me thinking about how I could dance a thesis on “Variability of Black-hole Accretion Discs: a theoretical study”!) The initiative is sponsored by Science and there's even a money prize for the contestants who best describe the scientific content of their PhDs in dance form, while putting on a creative and artistic show. Unfortunately it is too late to take part in the 2010 competition but there's always next year. In the mean time, think about it: how would you dance your PhD?

Hey babe, check out my dance moves

Picture the stereotypical scientist: male, shy, lacking social skills, single and, most likely, a disaster on the dancefloor. But here is an example of how science can be used to improve one's social life: research your way into impressing potential partners through dancing.

It takes no more than one night out clubbing to see that some men look hotter than others when they dance. But what exactly are the lousy dancers doing wrong? What are the key moves that work to increase your sex appeal? According to a carefully conducted scientific experiment at Northumbria University, where 3D avatars of male volunteers dancing were shown to straight women who evaluated their performance, this is bad:

video: Northumbria University

Plodding in a circle? No. Moving your arms and legs while keeping the rest of your body still? Forget it. Head-banging doesn't work either. Women don't seem to find men with repetitive dance moves attractive. Instead, they prefer movements showing variability and creativity which supposedly signal that the man is energetic, strong and healthy. According to the leader of the study, Nick Neave, the “brilliant dancers” are those that have different parts of the body “doing ever so slightly different things in time to the music”. Varied movements of the head, neck and torso appear to be key. So, men, all you have to do is mix up your moves and make sure your upper body is not still. The video below shows how it's done.

video: Northumbria University

Call me picky but I wasn't that turned on by that either...

What are these red things crawling on my skin?

I write most of my posts at night but this is a topic I could not deal with before going to bed. Bedbugs are all over the news these days. The reason being that, after about 40 years of absence, they are back to haunt us and bite us. New York City has been at the epicentre of the recent bedbug outbreak with hotels, high-street stores, hospital wards and even Google headquarters being affected. So now people are asking questions: why are they back and how can we kill them (without killing ourselves)? Bedbugs are a mystery. Unlike so many other bugs, they do not transmit disease. Scientists have even tried hard to make them do so but failed in most cases. (Apparently, researchers in South Africa fed AIDS-infected blood to bedbugs but the virus died.) Because the bugs are clean and didn't bother us for a long time, research funding was directed to other areas. That is why there are not that many “bedbugs experts” out there. And that is why we don't know how to make them stop crawling on our skin and how to put an end to the bloodsucking. We do know what killed them back in the 70s, but the chemical DDT is not exactly environmentally safe so it was banned for public health's sake. To make things worse, the new bedbugs are even more resistant to pesticides than the ones we knew before. I suppose all we can do is wait for hard-at-work researchers and government authorities to find a solution to this problem. Until then, “Night, night, sleep tight, don't let the bedbugs bite...”.

photo: Allen Brisson-Smith, The New York Times Company

(Bummer, I'm all itchy now.)

Bread deserves a longer post

Those of you who know me know how much I love bread. Even if it’s not your favourite thing, you have to admit that it is rather fascinating how simple ingredients such as flour, water and yeast combine to give rise to a wonderfully textured and tasty food. The secret to a great loaf is in the yeast: the live, single-celled fungus (Saccharomyces cerevisiae) that makes bread dough rise. But how is it that those dried granules that come in the little paper packets you get at the supermarket come alive and make a mix of flour and water leaven? The best way to understand how flour + water + yeast = bread is to actually bake the stuff. I’m going to follow this very simple “No-Knead Bread” recipe. No kneading means you don’t have to spend two hours in the kitchen mixing, folding, pressing and stretching the dough. The yeast does all the hard work for you but it needs time – this recipe requires 14 to 20 hours for the bread to rise. Trust me, it’s worth the wait – and you’ll learn some exciting science along the way!  

So, let’s start with the ingredients (for 1½-pound loaf):

3 cups all-purpose or bread flour, more for dusting


¼ teaspoon instant yeast


1¼ teaspoons salt


Cornmeal or wheat bran [or more flour] as needed

And follow with effortless mixing:

1. In a large bowl combine flour, yeast and salt. Add 1 5/8 cups water, and stir until blended; dough will be shaggy and sticky. Cover bowl with plastic wrap. Let dough rest at least 12 hours, preferably about 18, at warm room temperature, about 70 degrees [ºF = 21 ºC].

In step 1 of bread making the dried yeast, which consists of dormant cells of Saccharomyces cerevisiae, is reactivated. The fungus awakens as it comes in contact with warm water. The slow process that follows is called fermentation. Once reactivated, the yeast starts converting the carbohydrates in the flour into the simple sugars it likes to feed on. This reaction releases carbon dioxide and alcohol into the bread mix. Most carbon dioxide gas does not disappear into the air: it gets trapped inside the dough because of the gluten in it, formed when water is mixed with two proteins in the flour, glutenin and gliadin. The long, slow rise also helps the gluten molecules become aligned in a way that gives the dough a strong, elastic texture. The gluten structure traps air bubbles inside it, which are filled with the carbon dioxide released by the yeast. The more gas is released, the more the air cells inflate making the dough rise.  

(If the mixture was less wet and the rising time faster, as in other bread-making processes, the dough would need to be kneaded to help the gluten molecules align and give it the right structure and elasticity.)

2. The dough is ready when its surface is dotted with bubbles. Lightly flour a work surface and place dough on it; sprinkle it with a little more flour and fold it over on itself once or twice. Cover loosely with plastic wrap and let rest about 15 minutes.

3. Using just enough flour to keep dough from sticking to work surface, or to your fingers, gently and quickly shape dough into a ball. Generously coat a cotton towel (not terry cloth) with flour, wheat bran or cornmeal; put dough seam side down on towel and dust with more flour, bran or cornmeal. Cover with another cotton towel and let rise for about 2 hours. When it is ready, dough will be more than double in size and will not readily spring back when poked with a finger.

When the dough is folded over and shaped into a ball, the air cells inside it are moved and get distributed more evenly. The yeast, now highly active, keeps releasing carbon dioxide making the dough rise much faster than before. At the end of steps 2 and 3, air cells are inflated and homogeneously distributed throughout the bread dough giving it the perfect consistency.

4. At least a half-hour before dough is ready, heat oven to 450 degrees. Put a 6- to 8-quart heavy covered pot (cast iron, enamel, Pyrex or ceramic) in oven as it heats. When dough is ready, carefully remove pot from oven. Slide your hand under towel and turn dough over into pot, seam side up; it may look like a mess, but that is O.K. Shake pan once or twice if dough is unevenly distributed; it will straighten out as it bakes. Cover with lid and bake 30 minutes, then remove lid and bake another 15 to 30 minutes, until loaf is beautifully browned. Cool on a rack.

Once the dough is in the oven, the heat will continue to make the mixture rise as more carbon dioxide is released and the air cells expand. The yeast is eventually killed as the temperature continues to increase. The mixture stops rising, the gluten hardens, and the dough becomes solid. The bread is ready! Enjoy!

The end result (topped with a tomato mix).

Dear Fault, could you please wait until October?

Earthquakes are a frequent topic of conversation here in Santa Barbara where I'm spending the summer months doing research. California is a region of high seismic risk and the San Andreas Fault, which runs through the state, is believed to have accumulated enough strain to produce the next big Californian earthquake (or “Big One” as people call it around here). As you can imagine, I wasn't at all amused to be reminded that a quake of magnitude 7 or more might be coming my way. At least today's lunchtime chat brought to mind all the interesting stuff I learnt about geology back in school.

So why is it that the ground beneath our feet shakes every now and then? The outermost layer of our planet is divided into pieces called tectonic plates that are in constant (but slow and imperceptible) movement. The boundaries of these blocks, made up of many faults, rub against and bump into each other. The edges of the plates are rough and tend to get stuck together while the plates themselves keep on moving. This builds up pressure at the faults where the energy that results from the deformation of the moving plates is stored. When two plates have moved far enough apart to overcome the friction between their boundaries, the stored energy is released and an earthquake occurs. As for the San Andreas Fault  – just a few miles east of where I'm currently living – it is “locked and loaded”, as the director of the Southern California Earthquake Center puts it. I can only hope that it doesn't decide to release its energy while I'm here.

photo: David K. Lynch

Cork, the natural choice

It was only when I moved to England that I realised wine bottles could have plastic stoppers or aluminium screw caps. Back in Portugal cork was always the natural choice.

The reason for the widespread use of cork stoppers in Portugal may be historic or economic, as the country produces over 50% of the cork harvested annually in the world. However, these days the preference for cork is also connected to sustainability, low carbon cost and biodiversity protection. Cork is a natural substance with amazing properties (buoyancy, elasticity and impermeability, to name a few) that make it ideal for use in wine bottles. It comes from the bark of cork oak trees which is sustainably extracted every nine years, the length of time required for the bare trunks to renew themselves after harvesting. The cork oak trees, endemic to the western Mediterranean, naturally sequester atmospheric carbon and can live for more than two centuries. It is therefore not hard to believe that the carbon cost associated to the production of cork stoppers is significantly lower than that linked to screw caps or plastic stoppers. But there is more to add to the list of environmental benefits of cork. As emphasised by WWF, choosing cork helps preserve the rich biodiversity of the western Mediterranean and reduces the risk of fire and desertification.

There is much environmental science (and more) to discuss over a glass of wine at your next dinner party. Just make sure the bottle has a cork stopper! 

photo: APCOR

Is the moon going to disappear?

I would like this blog to be about science in general so I wanted to resist the temptation of posting about Astronomy again so soon (fail!). Do forgive me but this is too cool not to comment on: “Did you know the moon is shrinking?”. Yes, the moon, the only celestial body humans have set foot on, that bright, big object in the night sky where satellites have been to so many times does not stop surprising us. New images from NASA’s Lunar Reconnaissance Orbiter show widespread wrinkle-like features in the moon’s surface. These scarps are interpreted as being due to global cooling and resultant contraction. The planets and their satellites formed in a violent environment: collisions (as well as radioactive decay) resulted in a hot primordial moon. If a hot object has no heat source to maintain its temperature it eventually cools down. That’s what is happening to the moon. What is surprising is that it is still happening even though the moon formed over 4 billion years ago! Indeed the scarps revealed by NASA’s spacecraft are relatively recent having originated in the past billion years or so showing that the moon has not stopped shrinking. Astronomers believe our satellite will keep on contracting until its interior is cool enough. But worry not, the moon is not going anywhere: since it formed it “lost” only about 200 metres of its 3476 km diameter.

photo: Luc Viatour

As if being ugly wasn’t bad enough

It wasn't until I saw this slide show that I found out about the blobfish. This funny-named fish is probably the most miserable looking animal that I have ever seen, with a “face” worse than that of a Cleveland worker with a bad case of the Mondays. The Psychrolutes marcidus, its scientific name, is a deep-sea creature that inhabits the southwest pacific waters off the coast of Australia. It lives at depths of up to 800 meters. Because the pressure at such depths is so high, normal fish would have to swim to exhaustion not to sink. Their internal gas-filled organs or gas bladders (the evolutionary equivalent of lungs if you wish) would not be efficient in helping them keep their buoyancy. The blobfish survives because the gelatinous material it is made of is slightly less dense than water. The creature has no muscle: it floats for a living and it feeds off drifting mollusks and other organic matter. Even though the blobfish is harmless and inedible it is in risk of becoming extinct due to over-fishing as it frequently gets caught in fishermen’s nets. 

photo: Caters

“Stars fall as rain”

If you looked at the night sky late last week you probably saw a few more shooting stars than normal. When “stars fall as rain” as Chinese astronomers reported in 902 AD, appearing to come from one point in the sky, a meteor shower is taking place. In events such as this stars don’t actually fall. What we see are meteors, fragments left behind by comets that burn up and glow as they pass through the Earth’s atmosphere. Comets are small bodies of the Solar System composed of icy gas and dust. When a comet passes close to the Sun and heats up, some of its dusty-icy material evaporates creating a stream scattered along the comet’s orbital path. Comets such as Swift-Tuttle – the responsible for last week’s meteor shower – leave a stream that intersects the Earth’s orbit. As our planet travels around the Sun, it encounters the debris left behind by the comet at regular and predictable times and a meteor shower happens.

photo: Mila Zinkova, Wikimedia Commons

Desbloqueador de conversa

This blog's inspiration is a Portuguese expression: "desbloqueador de conversa" (literally, conversation unblocker). Something you say at a dinner party when silence kicks in or when some of the people at the table are having a heated argument and ruining the atmosphere. A snappy way of changing the topic of conversation: "Did you know that the penis of the blue whale can be 8 feet long?". Go figure, my favourite ones are related to science. Actually, what I find interesting is the science behind the fact so that is what I plan to write about. Use it if you need it.