Tuesday, 30 January 2007

How to... yo yo diet

If you are at all conscious about your body, and lets face it most of us are (not as much with the guys but still), then at one point or another we have been at least tempted to try some sort of fad diet.

The idea behind most of these (apart from making lots of money for their creators) is that be eating only certain things (ie no carbs, or no fats) or eating in certain ways (only raw food) or by substituting "supplement shakes" for meals one can lose weight.

Of course there is one other method by which people often try to lose weight and that is simply by starving themselves. And it is this rather than the others that I want to focus on today.

Our bodies are wonderful mechanism - in times of plenty we store the food for times where food is rather scarce, however one other thing is that in times of scarcity our bodies will also slowdown so that the stores we have can be made to last as long as possible, this is especially useful if you do not know when more food will be available again.

So what happens when you try to lose weight by cutting calories alone:

  1. Your body thinks (rightly) that it is a time of scarcity of food
  2. So your metabolism slows down to conserve your food stores -fats, glycogen (stored carbs) and protein
  3. Since you are still not taking in enough food to subsist, even with the reduced metabolism you body starts to burn its stores.
  4. Your body is used to operating mainly of carbohydrates since these are the easiest to use so you store of these, glycogen, is used first.
  5. This leads to a quick loss of a couple of kilos since the break down of glycogen releases a lot of water.
  6. Once the glycogen is used up the weight loss slows, and the body now must turn to an alternate fuel.
  7. The blood-brain barrier is impermeable to fats, so either that stored fats have to be broken down (a difficult task) or instead protein can be used (what actually tends to happen)
  8. The primary weight loss now is muscle wastage as the proteins from the muscles are used in respiration (which is the process of releasing stored energy not the process of breathing in and out, which is a small part of the former).
  9. If this continues for some time important muscles such as the heart can begin to degrade, which as you can imagine causes no end of life threatening problems.
  10. If at some point you do stop fasting, you body suddenly goes into "time of plenty" mode (which it is at least relative to the fasting) in which the main aim is to restore the used body stores of energy (and of which fat is the most efficient).

Now some people go through this process and are quite pleased with their weight loss, which is why the get to step 10, unfortunately this leads them to put on weight and quite often this is more than they lost so they start again. So it becomes a bit of "Lather, Rinse, Repeat"and of course this can go on and on and on ... Hence the "yo-yo diet" moniker.

Of course the observant of you will have noted that no where did I mention using the stored fats, this is where exercise comes in to the equation, you can only burn fat through prolonged aerobic exercise - ie long and relatively slow (and steady) exercise such as jogging, swimming, and walking that sort of thing

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Friday, 26 January 2007

Fridays Physical Law - Force and Accelleration

As we saw last week a change in motion of an object requires a force to act on the object. Of course with change in motion we mean that an object can speed up or slow down or simply change the direction of motion - all of these acts are covered by the term acceleration.

Technically acceleration is the rate at which the motion changes, or the change in motion divided by the time it takes for the change. So like velocity is how fast you are moving (changing position) acceleration is how fast you are changing your motion (velocity).

So when ever we have a force acting on an object we get an acceleration. Of course multiple forces causing multiple accelerations could also be acting to reinforce or cancel out each other. Two people pushing a car (from the same end) make it twice as easy to get going, whereas if one was pushing forwards and the other pushing equally backwards then these would cancel out.

If we increase the force then we increase the acceleration, but what else effects this relationship? The answer to that is mass, the heavier an object the more force is required to get the same acceleration as a lighter object. This is described in Newton's Second Law F = ma.

A force in the direction of motion increases the speed, and a force counter to the direction of motion will decrease the speed. A force at an angle to the motion will cause a change in direction of motion as well as an increase/decrease in speed.

We also have the interesting case of a force at right angles to the motion, this will not cause any change in speed only in direction. And if this force is always at right angles to the motion then the object will continue at a constant speed the changes in direction will cause it to move in a circle. In this case we call the force a centripetal force, meaning center-seeking, but more about that another time.

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Wednesday, 24 January 2007

How to ... Get cancer from a Cellphone

The energy in individual RF (radio frequency) photons (individual photons interact with individual electrons in atoms) is far to little to cause ionisation (when the electron is completely removed from the atom) or any other known mechanism for causing cancer. So if you want to get cancer from your mobile phone or your wifi network or your microwave (outside of 24/7 use) I will outline a method as follows

  1. Take your favourite RF device
  2. Open up the device and remove the circuitry
  3. Depending on the method of oscillation, you will need to alter the capacitance/inductance or the resistance of the oscillator circuit, or by reprogramming the chip.
  4. The frequency of oscillation was probably in the range of 10 - 1000 MHz (million of cycles per seconds) this will need to be increased to 100-1000 THz (million million cycles per second) ie from radio/microwaves to visible light.
  5. This causes an increase of photon energy by a factor of 10 million or so, enough to now ionise some matter and hence be a possible cause for cancer.
  6. Put device back together and turn on.
OK so a lot of people have concerns about RF radiation, for the most part these fears are unfounded in science, however this does not affect those that are worried. Of course this is not mean that a mechanism may be found in which this frequencies could have a detrimental effect outside of heating.

On the note of heating, as long as the RF radiation is not continuous (ie you have breaks from having you cell phone next to you ear) then the heat rapidly dissipates and is not an issue.

If anyone wants more information about recommended limits that were discussed at the last International Union of Radio Science (URSI) General Assembly, I can provide links to abstracts etc. It was actually a very food and informative session.

Also I would like to thank Jennifer Oullette of Cocktail Party Physics for the inspiration

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Please, Your Tshirt is a Security Threat

A passenger has been barred from an International flight from Melbourne to London for wearing a tshirt which calls Bush "The worlds #1 Terrorist" on the basis that the T-shirt could have upset other passengers.

And to make matters worse:

Qantas issued a statement saying comments made verbally or on a T-shirt which had the potential to offend other travelers or threaten the security of aircraft "will not be tolerated."
Now how on Earth does this threaten the security of the aircraft? Is the Tshirt going to spontaneously combust in mid-air?

Still it is good to know that America's allies are standing proudly along side the USA as they fight the "War on Liberty" all over the globe.

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Schrodinger's Cat

Ok the other day I was standing in the kitchen cooking dinner for the family and looking out the window I could see our cat lying on the concrete by the washing line, and then looking again i could see another very similar cat lying on top of the compost bin. Looking closely I could not make out any differences between them, nor on either cat could I see our cats bright yellow refelective collar (which proves very usefull on an all black cat at night).

To this day I have never seen another lithe black cat in the neighbourhood, and our cat has never been what you would call friendly to other cats (many late night fights are started below our bedroom window).

My wife went down to see the cats and by the time she had gone down the stairs to the yard the cat by the washing line had disappeared and our cat was lying relaxed on the compost bin.

Maybe what I was seeing was the famous Schrodinger's cat, well not exactly (since that had to do with whether the cat in the box was alive or not) but certainly the parallels to quantum mechanics are abound.

Obviously the "catfunction" was a superposition of two states and when my wife went out to make an "observation" the catfunction collapsed to the compost bin state.

Maybe? Or could it be something else?

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Quote of the Year (well so far)

My wife the other day came up with an absolute gem

Reality has no meaning for them, it is not where they live.

Now in context she was complaining about her parents but it can clearly be seen that this description could be applied to all sorts of groups of people.

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Monday, 22 January 2007

The Britons do me proud

As I mentioned last week racist bigotry was apparent in the UK's "Celebrity Big Brother" TV show. But the watchers who were upset enough to complain to the TV station in record numbers have also spoken out against the perpatrator of the offense and voted her off in last week's elimination.

There is hope for them yet obviously.

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Friday, 19 January 2007

Blog Beta

While blogger itself may now be out of beta, this blog most certainly is not. There will be random changes to how things are on here (though mostly it will be small tinkering) as I find new things to add and better ways to present things and add the rest of the blogs that I try to read as often as I can

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Only In England...

Only in England could some D-list celebrities (who could arguably be described as quintessential English "slappers") think that they are better than possibly the world's most famous movie star (she is a household name in India) purely because she is different to them.

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Naught of Comet McNaught

Why is it that when the best opportunity of my life time to view a spectacular comet occurs it is cloudy?

It has been cloudy here all week and I am getting frustrated. Today has been horribly grey but even on the sunny days we have had this week there has been plenty of high cloud, well at least enough to prevent a decent attempt at viewing.

Oh well at least I saw last year's (OMG that makes it seem so long ago) transit of Mercury - and helped many others see it too.

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Wednesday, 17 January 2007

Friday's Physical Law - Motion

Welcome to Friday’s physical law (FPL) - a weekly look at how physics governs everything, and as this is the first of this series I will be starting somewhere we hopefully can all understand with simple motion.

Everyday experience would seem to indicate that the natural state of motion of an object is a rest. An object in motion will slow down and stop unless a force is acting on it. This was the reasoning of Aristotle. Of course this is what we see here on Earth in the presence of what we now recognise as friction.

We can quite easily see the truth of what happens if we remove the force of friction, imagine if you will you are on the ISS and you push off one wall, you keep drifting until you hit the other wall, this is because now the friction that is acting on you in now minimal. We can see examples of reduced friction on Earth such as skating on ice, or ball bearings.

This leads us to the understanding that we now have, Newton’s first law: That an object remains in a state of steady linear motion unless a force acts on the object. This means that an object at rest remains at rest and an object moving in a straight line will continue at the same speed and direction of motion unless a force acts on it

And our experience of friction that slows down the object is recognised for what it is: a force on the object acting against its motion. It arises from the interaction of the object and the media (substance) through/on which the object is moving. We can tell definitively about the existence of friction by the heating of an object as it slows down, the friction dissipates the motion (kinetic energy) of the moving object turning it into heat.

The effect of friction itself depends of only two things:

  1. The object which is moving (i.e. what it is made of, its shape and weight)
  2. The media through/on which the object is moving

As you can see the former is really a combination of a number of factors - the most important being those listed in the bracket. Obviously if changing what the object is moving through makes a difference then so will changing the object, the shape is important, the less contact there is the less friction there will be (think of a ball bearing), and the greater the mass the stronger the interaction between the object and the surface it is moving on (ok so to be completely honest the weight factor only applies to motion across a solid surface and not to motion through a fluid).

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Tuesday, 16 January 2007

How to ... Challenge a scientific theory

As an incentive to regular updates I am forcing myself to have a couple of little weekly series. And this how to guide will be one of them, it will be a somewhat tongue-in-cheek look at various issues that take my fancy, it will also be fairly brief.

In this first issue I will set up a list of rules for what to do if you want to challenge the mainstream - perhaps we could forward it to the DI (and maybe contrarians and denialists of all flavours). So any here we go...

1: Whatever you might think of the prevailing theory, you have to admit that it has become the mainstream position on its subject by virtue of explaining the data better than anything else.

2: Therefore your hypothesis should also be able to reproduce the existing data - and in most cases the existing theory will be a special (or limiting) case of your hypothesis.

3: If there should be some data (actual hard experimental data not just some objection you have) that seems to fall outside the existing theory then your hypothesis must explain this.

4: Your hypothesis must make predictions for the results of future experimental findings (preferably predictions that differ from those of the existing theory otherwise how will anyone be able to tell the difference between them).

5: After much testing by the scientific community at large if you hypothesis has accounted for all of the observed data especially that which cannot be accounted for by any other method - then and only then have you succeeded in your challenge.

NOTE: A very important thing to consider on this process is that if you have to resort to a public relations campaign to overcome your failings at any of the above steps you are automatically disqualified from the process.

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Welcome to my (little corner of the) world

I thought I would start off this new life of mine and I guess it would be appropriate to tell you a bit about myself and what I am thinking about doing with this blog.

I am a doctoral student in physics. In addition to my research I tutor and demonstrate first year physics, and do programming for various researchers about the university, which all keeps me very busy so I intend for posts here to be a bit sporadic but I will try to be regular-ish with a couple of posts a week – although I do intend to up this rate at some point the in the future.

I have an interest in science history and education, as well as the interaction of science and culture. And this is largely what I will be blogging about: a journey of the history and development of science throughout the ages as well as the implications of modern science (in particular Relativity – a little passion of mine although not my research area).

I am indebted to several of the scienceblogs crew particularly Orac and Ed as well as Phil Plait from Bad Astronomy for providing the inspiration to get me into this and for giving me ideas about what to write about and indirectly how to go about it. As a skeptic and a scientist a lot of what I might tackle here has already been done so well by others but I will endeavour to add something to the blogosphere.

So thank you for your time to come here and partake in my delusion (I will explain this at some later date) that what I have to say matters and that I can have an influence of the scientific literacy of the next generation.

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