Scientific Scribbles

The voice of UniMelb Science Communication students

Aquaponics: is it the same as employing a fish to be your gardener?

                          image courtesy of Nicole McCleaf on Flickr

I’ll admit: when I first heard about aquaponics I thought that someone was using an overly complex word to talk about akin to water polo (which is not a game involving horses and swimming pools).

It wasn’t until I was reading through some literature regarding aquaculture now providing half of all fish consumed by humans that I realized that aquaponics was the innovative cousin of fish farming. That is to say that aquaponics integrates two systems in order to create a self-sustaining, closed-loop ecological system.

Read: throw away your watering can and fertilizer as this system essentially puts your fish in charge of feeding and watering you garden.

Do I have to train my fish? How are they qualified to do this?

Putting it very simply, an aquaponics system works on the basis that the fish produce the nutritious substances that sustain the plants, while the plants themselves act to filter the water for the fish.

Of course, it is more complex than that, but that is the basic breakdown.

This symbiosis of sorts demonstrates the innovative design principles that can be taken directly from nature: a process generally referred to as biomimicry.

In natural freshwater systems, it is entirely common to see plants growing either alongside or within the water. As such, it doesn’t take any special instructions for the fish to induct them into their newfound responsibilities, as they instinctively go about their fishy business. Logistically, all the fish need to do is continue to produce waste in the form of ammonia, which is then converted into nitrate by the variety of microbes and bacteria that mediate the conversation between the fish and the plants.

Wait: so, the microbes are actually in control here? Are they qualified to look after my plants?

Given the delicate balance of such a complex system we’re trying to achieve here, it would be particularly callous to simply leave the fish in charge. The microbes do play a very integral part within this process as they help to make the fish waste into readily available nitrate-rich fertilizer for the plants to subsist on.

This process means that these plants are not dependent on artificial fertilizers or pesticides due to the fact that the microbes also generally dissuade insects from interrupting this process. As such, entirely organic, nutritionally rich vegetables are handed to you for the simple price of becoming the courteous landlord to the original odd couple: a few fish and some lazy plants.

Pardon the pun, but “what’s the catch?”

When mitigating a cosy living space between three different species of organism, as a landlord it is important to get the living circumstances right and to keep them appropriately maintained. As such, keeping a neutral PH balance is key.

If the PH leans towards being too acidic then the fish and microbes will most likely find it difficult to survive. This would then throw off the delicate balance as your primary gardeners will be unable to fulfill their tasks of producing waste and making viable food for the plants.

And, of course, if the PH shifts the other way into becoming to alkaline then the plants generally suffer.

So, it appears the cost of running such a harmonious system is the almost daily attention needed to maintain PH levels. Otherwise you can leave the gardening up to the dream team of fish and microbes.

 


Rise of the Planet of the Jellyfish

It’s no secret that our oceans are suffering. Ocean acidification is a decrease in pH as a result of carbon dioxide uptake from the atmosphere, and it is becoming a huge problem. While a more acidic environment may be detrimental to many organisms and even entire ecosystems, some species may totally dominate. These species are predicted to breed faster, grow quicker, live longer and may consume too much food. Are you picturing a massive, frightening creature that lurks in the deepest, darkest depths of the ocean? Well you’d be wrong. The culprit is the jellyfish, and they don’t even have a brain.

The deadly Box jellyfish. Source: Flickr

To be specific, the Box jellyfish and the deadly Irukandji jellyfish are examples of species that may perform well with the changed conditions associated with climate change. As the oceans become more acidic, scientists are worried about the effect on key organisms and how it will impact various food webs. Copepods are small crustaceans and are a major food source for many fish, whale and bird species. If copepods are affected, an entire ecosystem will consequently change.

Edd Hammill and colleagues at Utah State University tested the effects of acidification and predator response by keeping samples of zooplankton in either normal seawater or acidified seawater and added box jellyfish to half of the tanks. The experiment ran for 10 days and they recorded the number that survived in each condition.

A tiny copepod. they are a major food source for many marine species. Source: Flickr

As expected, both acidity and the presence of box jellyfish reduced copepod numbers, but when in combination, there were far more deaths; 27% more than the sum of each one individually. In the normal seawater jellyfish consumed 37% of the copepods but in the acidified seawater they consumed a massive 83% of the copepods.

Scientists aren’t entirely sure about the results. Are the copepods weaker in acidified seawater and so are easy prey for jellyfish? Or are the jellyfish not as affected by the acidified water and are needing to consume more prey? While it is a simple experiment it raises important questions for the future of our oceans. If box jellyfish are able to perform better than other species, it could have dramatic consequences.

CSIRO scientist, Dr Lisa-Ann Gershwin, says that global warming could also make the deadly Irukandji jellyfish a problem, particularly in the northern rivers. She believes that warmer temperatures could see species of jellyfish breed and grow faster, as well as live longer.

The tiny Irukandji jellyfish. It is about the size of a $2 coin but its sting can be fatal. Source: Flickr

A sting from an Irukandji jellyfish can cause pain, vomiting, pulmonary oedema, high blood pressure and heart failure that can cause death. As for the box jellyfish, a sting from these guys can be fatal in about 3 minutes! This is not a species you want to cross when you’re going for a swim.

So is now the time to panic and never go in the ocean again? Not at all. Dr Daniel Butcher, a senior lecturer in marine biology at Southern Cross University states that it is hard to predict exactly how jellyfish will respond to warming temperatures. The temperatures on the east coast of Australia are strongly influenced by the East Australian Current (EAC) which can vary a lot. So these fluctuations could mean that, yes, we have warmer waters but it could also mean that we get cooler waters. It is hard to know at this stage how organisms will respond but it is important to be aware that it could be an issue. The CSIRO is in the process of making a system to try and predict when and where Irukandji jellyfish will occur.

More research is needed on this issue, but it definitely shows that there is possibility of jellyfish dominating and altering ecosystems on a global scale. I guess they aren’t so spineless after all…


Gastrophysics: How to create a perfect meal through science

When was the last time you feel really enjoyed your food? You may think of one perfect candle-light dinner with your loved one at a fancy restaurant. Or maybe a simple dish on family gathering at Christmas night. Whatever it was, we would say that what made it delicious was not just the taste of the food but also the memories and joyful you had.  Eating is one of the most complicated activity we always do. It is not only about how our tongue tastes the food- the sweetness, sourness, bitterness, saltiness. We not only eat with our mouth. We eat with our eyes and ears! How could that possible? Gastrophysics reveal them all.

What is Gastrophysics?

Variety of Italian food with wine on dark wooden table. Source: Flickr

It is a scientific discipline which combines gastronomy and psychophysics. The experts systematically observe the way our senses (eyes, nose, and ears) and surroundings can influence our appetite. They called it “the new science of eating”. Our senses make us build expectations: when we see a picture of food in menu book, we speak in our mind, “Its colour so tempting, so it must be delicious”- and end up eating in big portion. We often made the decision in our mind even before we taste the food. That’s what experts said nothing “neutral context’’ in eating. The complex relation in eating makes this field become more interesting not only for scientists (neuroscientist and psychologist) but also chefs, food producers, and even musicians.

What kinds of things can affect our appetite?

The famous Indonesian cuisine: Nasi Goreng and Sate. Source: Flickr

A lot of things! They can be the appearance of the food; the shape, colour, and weight of the plate; background music or noises; lighting; the mood we have and even the person we are eating with. All of them makes our eating experience far away from objective. We don’t merely use our tongue to taste the food, but our perspective shaped our overall judgment towards the food. One awkward example is using red plate can suppress our appetite than using the white one. It simply because when we see red colour, our brain will interpret it as “danger” and “stop” sign. The flavour of the food in our mouth also can be manipulated by the sounds around us. A research shows that people will feel their coffee more bitter when they hear high-pitched noise from the coffee machine. Restaurants use this idea. They use classical music to makes costumers feel relax and eat slowly and thus altering their appetite. The sound of the food itself can make us taste something different. A research shows that when the crunchy sound of potato chips is getting louder, eaters will feel that the chips are 15% fresher. The louder the sound, better the taste. This trick has been used by food producers to increase their product sale.

What benefit can we get from it?

Gastrophysics is very useful for us. By understanding the way our senses influence us, we can control our diet. If you want to lose weight, you can use a flat and small plate because it can make you think that you already took a lot of food (it gives you a visual illusion). If you want to reduce your sugar consumption, should first find out what is the common way you eat sweet food such as ice cream. If you used to eat ice cream using a white bowl, then your brain will expect something tastes sweet when you are eating other food in a similar dish. Even in hospital, we can simply alter patients’ appetite by serving nutritious food in an appealing dish using different colour combination and texture. You can also have a delicious dinner like at high-end restaurant in your house just by turning on relaxing music while eating. Knowing these tricks can make you have a perfect meal every day! 😊

 


On Mathematical Beauty in Physics

“Mathematics, rightly viewed, possesses not only truth, but supreme beauty – a beauty cold and austere, like a sculpture, without appeal to any part of our weaker nature, without the gorgeous trappings of painting or music, yet sublimely pure, and capable of a stern perfection such as only the greatest art can show.”

— Bertrand Russell

Physics, the most fundamental and abstract of the sciences, is inextricably linked to mathematics, the language it is expressed in. Central to physics is the concept of mathematical beauty. This aesthetic quality, whilst not easily definable, is not subject to any doubt to those who can appreciate it. A study of the brain scans of a group of mathematicians at University College London reveals that beautiful equations have an emotional effect that is not unlike great art and music; observed here was an increase in activity in the medial orbito-frontal cortex—the emotional part of the brain—when gazing at equations whose beauty they rated highly.

Just like art, mathematical equations are capable of giving a sense of great beauty. Pictured here is “The Creation of Adam” by Michelangelo on the ceiling of the Sistine Chapel (credit: Wikipedia)

The lack of a precise definition of mathematical beauty, and beauty itself being a subjective concept, may lead one to dismiss the subject as not worthy of further discussion. However, a naïve survey of the field reveals a general agreement on the underlying characteristics of what makes an equation “beautiful”. Amongst the not-too-tangible qualities often cited to constitute mathematical beauty are simplicity, symmetry, and elegance. Euler’s equation, highly regarded among mathematicians, is one such example where the union of five constants is made in a rather simple and neat fashion.

Euler’s identity

The expression of the fundamental laws of nature in simple mathematical equations thus carries in it an element of poetic beauty. The rather succinct Schrödinger’s equation below, for instance, describes the behaviour of atoms and their constituents down to the finest detail, which if solved, gives the probability of finding a particle at a given position.

Time-dependent Schrödinger’s equation

A personal favourite of mine is the set of Maxwell’s equations. In this elegant formulation we find the marriage of two previously unrelated realms of electricity and magnetism. As an undergraduate, a charismatic lecturer took us through a long journey towards the finale of the four neat equations, whereupon he exclaimed with certain gravity in his voice, “And that’s how Maxwell came up with these equations of electromagnetism, right here in this building”. It sent a chill down my spine which I have never quite forgotten.

Maxwell’s equations

“A physical law must possess mathematical beauty.”

—Paul Dirac

There was perhaps no one amongst the 20th century physicists more obsessed with mathematical beauty than Paul Dirac. A trained engineer, he was spurred to take up physics by Einstein’s work on relativity and later became a pioneer of quantum field theory. To Dirac, it was precisely this aesthetic quality that makes the general theory of relativity great, despite the greater mathematical complexities and its going against the principle of simplicity.

Einstein’s field equation describing the curvature of spacetime

So obsessed was Dirac with mathematical beauty it led him to state “It is more important to have beauty in one’s equation than to have them fit experiment”. Quite notably, in the James Scott Prize lecture Dirac delivered in 1939, he offered a devastating insight in a just few short lines: “…the mathematician plays a game in which he himself invents the rule while the physicist plays a game in which the rules are provided by Nature, but as time goes on it becomes increasingly evident that the rules which the mathematician finds interesting are the same as those which Nature has chosen.”

Dirac equation

Few physicists would today contest the beauty of his eponymous equation. Deceptively simple, the equation united the then distinctly separate special theory of relativity and the quantum theory to describe the electron, and remarkably predicted the existence of antimatter—an outlandish claim at the time, but is now taken for granted to constitute half of the early universe, as per the Big Bang theory.

Unlike paintings, only those who understand the meaning behind the mathematics can truly appreciate the beauty of an equation. Pictured here is “Saturn Devouring His Son” by Goya (credit: Wikipedia)

This aestheticism will regrettably remain inscrutable to many. In the words of Dirac, mathematical beauty is “a quality which cannot be defined, any more than beauty in art can be defined, but which people who study mathematics have no difficulty in appreciating”. It is presumably this which led Bertrand Russell to call it cold and austere.


A Symptom That Keeps You Eating: Facts about Prader-Willi Syndrome

Imagine the feeling of hunger when you don’t have access to food, 24 hours every single day. You are always eager for any kind of food, but never feel full. Sounds ridiculous? This is life with Prader-Willi syndrome.

 

What is Prader-Willi Syndrome (PWS)?

Prader-Willi Syndrome (PWS) is a complex multisystem disorder, occurring 1 in 10 000-15 000 new born babies, with equal frequency in both genders. it is a genetic defect caused by deletion or change of chromosome from mother’s copy.

 

What do people with PWS look like?

People with PWS have series symptoms, physically and emotionally. A typical face of people with PWS would be almond-shape eyes, narrow nasal bridge and thin upper lip. Babies with PWS have less muscle strength leading to poor suck and weak cry, which are probably the only two things that babies do. Most people with PWS have developmental delays, with average IQ 60-70, average adult height of 155cm for males and 148cm for females.

Food seeking and overweight characters begin between 1-4 years. They would eat unappealing food just because they can’t feel full. If food intake isn’t controlled externally, obesity comes along naturally. Obesity then causes heart disease, difficulties in breath and sleep and other chronic diseases.

People with PWS also have poor temper-handling, stubbornness, manipulative and autistic-like behaviours.

 

Born with it, live with it

Sadly, there’s no efficient way to prevent it or even detect it before delivery. kids with PWS will require constant care throughout their lives. the only thing a PWS family can do is to learn to live with it.

People with PWS and their families are facing unimaginable challenges in life. Feeding difficulty in early childhood is just the beginning. Poor academic score ay schools and irritable personalities sound tolerable. Excessive eating behaviour and central obesity are the most difficult to control. It is not surprised that a child with PWS eat a whole jar of peanut butter. Honestly, kids with PWS with keep eating till their stomach explode.

 

Early warnings about your kids with PWS and how to test

There aren’t many signs of PWS shown in early stages of development, comparing to adults. The most significant and efficient one is poor suck due to abnormal muscle. If your kid shows difficulty in sucking, it may be worthy to test thyroid function and type II diabetes. After 2 years old, developmental delay begin to show up. However, it is not till about 6 years old that the typical symptom of excessive eating can be noticed.

Normally, a simple test called DNA methylation analysis would help diagnose over 99% patients with PWS. Clinical diagnostic criteria have been developed but the genetic testing is necessary to confirm the diagnosis.

Early diagnosis is important to long-term management, so please be aware of the signs listed before.

 

Any treatments for PWS?

Unfortunately, PWS is a genetic disorder which can be treated, but may not be cured. Researchers all over the world are working on the improving quality of life of people with PWS. Special nipples can be useful for the poor suck while nutritional monitoring is required for the long-term weight management. For the growth deficiency, the growth hormone therapy has been widely used and well demonstrated to help maintain the body composition.


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