• scissors
    March 29th, 2011ImogenUncategorized

    Tea Vortex

    Sometimes it is easy to find anything more interesting than the work you should be getting on with. This morning I took a break from revision to make some tea. I had to use powdered milk but sadly it 1) refused to dissolve properly, and 2) tastes weird, so I didn’t drink the resulting brew and it remains on my desk. As my mind wandered from the mysteries of dielectric materials in capacitors I developed a fascination with stirring my now-cold tea.

    By stirring the tea and then placing the spoon perpendicular to the edge of the cup I can create a mini vortex. Milk particles orbiting in the vortex have more speed than those which continue to do a full circuit of the mug. This is because they seek to conserve their angular momentum. Angular momentum is equal to the product of the radius of the circle, the mass of the particle and its velocity. The mass does not change so as the radius decreases, the velocity must increase in order to keep the angular momentum the same.

    What is concerning is that this is only my second day of revision and my exams are still 6 weeks away. I dread to think what will be entertaining me in the weeks to come. My reflection in a spoon perhaps? Perfecting my “r” rolling? Actually between sentences I am already experimenting with rotating on my swivel chair by waving my arms around like an over-intent cheerleader.

    Whatever keeps us sane, eh? I suppose I’d better get back to work.

    Oh look it’s almost lunchtime!

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  • scissors
    March 24th, 2011ImogenUncategorized

    They say that there is no such thing as bad weather, only inappropriate clothing. However, as a carefree young girl-about-town (read: impoverished student with small handbag) I happened to be tragically ill-prepared one day when the weather took a turn for the worse. As luck would have it on this drizzly day I had cycled into university. In order to retain my right to scoff at fair-weather-cyclists I felt obliged to brave the precipitation, mac or no mac and so I set off on my merry way. At least, it might have been merry if I had worn my gloves.

    For some time I was perplexed as to why my hands were getting so nippy. They were disproportionately chilly compared to the rest of my extremities but I couldn’t work out why. It was only when I got back to my house and was fumbling with the bike lock I realised that there was a very simple reason: it all comes down to evaporation.


    Mastering evaporation. (safely)

    There are two main reasons for this chilling effect (chilling where things get colder, that is. Physics is nothing scary). These are firstly, the varying energies of different molecular states and secondly, the law of diffusion. Here’s how they work.

    Molecules (with a few exceptions) are found bound in one of three states: solids, liquids and gases. A gas molecule has more energy than a liquid molecule, which in turn has more energy than a solid. This energy takes the form of tiny molecular vibrations – generally measured as heat. As temperature increases the individual molecules gain more energy and so start to vibrate more vivaciously. As vibrations grow the molecules will gradually break bonds to their neighbours. This is why as you go from solid to liquid to gas the substance becomes less rigid and more free-flowing.

    When I was learning about molecular states at school we did a practical in the playground, swinging about hanging onto each others’ elbows. As our class’s “heat” increased we were ordered to progressively let go of each other and observed how much further we could rampage as a result. If you feel a desire to experience this yourself I suggest experimenting by grasping on to a friend while you are a) standing on plastic bags, b) standing on skateboards or c) at the mercy of a small footloose child. The less random movement occurring, the greater your chances of remaining bound to your fellow molecule.

    Particles always diffuse from an area of high concentration to low concentration. This is a fundamental rule in physics, and explains why the smell of burnt toast manages to permeate every room in the house. Water on a surface is of a higher concentration than water vapour suspended in the air, so eventually the surface will “dry out” as all the water evaporates in an attempt to even out the concentrations. The surface will also be left cooler, as we have seen before. Finally, moving air increases the rate of evaporation because the concentration in the air is kept much lower than at the surface as evaporated molecules are consistently removed.

    In order to escape from a liquid and become an unconstrained gas particle, a water molecule needs to gain some energy from the liquid first. So how does this relate to my cold hands? As the tiny water droplets left my skin they took some energy with them, making my skin feel cool (because it’s just lost some heat energy). My skin then had to burn stored energy (from food) to generate more heat to bring it back up to temperature – I wouldn’t recommend hypothermia as a great weight-loss method though.

    Instinctively, we already know all this, that’s why everyone blows on soup. By huffing and puffing you increase the rate of evaporation. The greater number of particles escaping the surface means the liquid loses heat energy. This makes your food (/drink, I’m never quite sure with soup) less likely to burn your tongue.

    So what’s a similar effect? A fan in a closed room will not actually cool the room since it’s only moving air around (if anything, it’s heating the room up by creating heat via friction in its moving parts). However, if it’s blowing air at you, you will feel less hot as the moisture on your fevered brow evaporates.

    And this is why my hands were so very chilly in the wind and rain. What I really needed was a good pair of waterproof gloves to keep me warm. In fact, I have some such gloves at my disposal, but I forgot them that fateful day. Maybe what I really need is a better memory, but unfortunately neurology isn’t my speciality. In fact, if anyone would like to break down the science of remembering things for me, I would always love to learn more.

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  • scissors
    March 19th, 2011ImogenUncategorized

    Once upon a time 8 years ago my fellow year 7s and I had to make a powerpoint presentation. Oh the fun we had with the animations, making pages of text fly in letter by letter, and bringing warped photos swooshing in from the sidelines. However, times have (thankfully) moved on and today’s trendy swooshing is coming from the viewpoint and not the subject matter. This is down to Prezi.

    The main idea behind this web-based tool is to create a non-linear presentation. You arrange your text, pictures diagrams et al on an infinite canvas and map a route between them, rotating and zooming as you go. To see what I mean watch any one of the public examples on the Prezi site. Click the “next” button and get transported on a visual journey.

    I have my dad to thank for showing me the future of presentations. He was searching for a new Google programme for making slides (possibly a subset of Google Documents), but instead happened upon Prezi. He introduced me to it but I have never heard about it anywhere else. According to the website they are now turning over a profit, so Prezi must be selling enough subscriptions to survive through word of mouth alone. I actually use it with a free student license, so I feel obliged to express my gratitude via some mild plugging.

    These are my 4 fave things about prezi:

    1. The unpredictable path makes it a bit more interesting.

    2. You can hide things by making them really small and then zooming in

    3. The audience gets a sneaky glimpse of slides to come as you move between images. Alternatively, this could spoil the surprise, but that’s where no. 2 comes in.

    4. None of my audience so far had ever seen it before, so they all thought I was some kind of technical whiz. Once you get the hang of the unfamiliar control pad, Prezis are actually quite easy to make. Just don’t tell my audience that.

    So yes, I am pro-Prezi. I find it such a great tool that I can’t keep it to myself. I just wish there was a way to spread the word among all of the Presenters of the world and none of their Presentees. Oh well, I suppose the mystery couldn’t last forever.

    A Prezi I made recently for a presentation on a Letter to the journal Nature about a new nano-scale imaging technique

    Go forth and present!

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  • scissors
    March 13th, 2011ImogenUncategorized

    MSG in a bowl, in a packet.

    What does MSG stand for? Makes Stuff Great? Or perhaps, Morbid Sauce Generator. I know which is snappier, but what’s the true story about this food additive? I want to find out how it is supposed to be bad for us and more importantly, whether it actually is.

    I mainly became aware of the controversy over glutamate due to the smug messages of “No MSG” on the front of a growing number of processed foods. I feel I am missing some vital information on why manufacturers think that people don’t want to be eating extra glutamate. Glutamate is a naturally occurring version of the synthesised MSG, which is glutamate stabilised by the addition of salt.

    Some of the various alleged side effects of consumption of MSG are numbness, tingling, headaches, nausea, rapid heartbeat, and for asthmatics, difficulty breathing. This website written by an American takes the form of a chain email, sent out to “inform” friends and encourage them to “blow the whistle on MSG”. The main point against seems to be that scientists inject infant rats with MSG to cause them to become obese so they can be used in studies on diabetes et cetera. However, the author of this article has not mentioned the relative levels found in food and that which the rats are given.

    After checking the cupboards of my student kitchen I was surprised by the lack of monosodium glutamate on ingredient lists. In fact the only place it was freely stated was as the second greatest component of Bouillon Stock Powder. This surprised me, since the product is organic and boasts “all-natural ingredients”. However, like most awkward topics, many other names for glutamate are now in use. These include hydrolysed vegetable protein (in pringles) glutamate (a natural result of the formation of soy sauce and cheese) and main constituent of marmite, yeast extract. Lots of lists also included the cover-all terms of “spices” or “natural flavourings”. Even the soy sauce boasted “no added MSG”, which is a bit misleading since glutamate develops naturally during the fermentation of the soy beans. If you are on a serious MSG-hunting mission then check out this page.

    So basically, MSG is in a lot of things we eat but we might not realise it. This means that if it is actually bad for us then this could be worrying. I contemplated catching some rats from Euston underground and conducting my own experiment by feeding them up with all the stock cubes they could eat. However, my student bedroom is cramped enough already and I signed something for the landlord saying I wouldn’t keep any pets, so I decided it was best to leave it to the professionals. So I looked through some studies to find out whether scientists have found any concrete proof that MSG is harmful.

    The first one I came across is titled “Monosodium Glutamate: Lack of Effects on Brain and Reproductive Function in Rats”. The title betrays the non-result. The abstract tells us that they injected infant rats with monosodium glutamate and then basically  tested whether it had an effect when they had grown into adults. In their words: “treated animals showed no adverse monosodium glutamate effects on the reproductive system and neural morphology”, that is, the cells of their brain and nervous system didn’t seem worse off for the dose of glutamate when they were young.

    Another article seems to think it has found a correlation between MSG and the release of growth hormone in rats. However, the injection of MSG these rats were given happened a few weeks after birth and was dosed at 4mg/g bodyweight. This might not sound like much, but for a 60kg human this is the equivalent to 240g of MSG. That’s like if I ate 20kg of parmesan in one sitting. Disregarding whether that is actually humanly possible, anyone would tell you that eating so much of anything is not going to be a good idea. Which is why although the consequences for the rats in this study were not good, I am dubious of whether this is relevant to our everyday eating habits. For example, you can die from drinking too much water but “normal” volumes of it are essential to our bodily functions.

    As they have been saying for centuries; “everything in moderation”. This also applies to glutamate. So basically, don’t eat more than a significant fraction of your bodyweight in marmite at once and you should be fine. I’m off to enhance my food.

    For more info check out this great article at the Guardian by Alex Renton, entitled If MSG is so bad for you, why doesn’t everyone in Asia have a headache?”

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