This was in Bath Physics Department, seems a bit out of place...
Sunday, 14 December 2008
This was in Bath Physics Department, seems a bit out of place...
Sunday, 23 November 2008
The reason I wanted to do this will become clear soon (as in I'll post on it). I wanted to simulate a lattice with as many sites as possible so that I can do some visualisation of renormalisation group ideas (again more on this soon). Instead of storing each site inside a byte of memory I store 8 sites in each byte and then use a bit of binary operating to get the bit I need. This means each site now only takes one bit of memory.
That was the easy bit. The hard bit was simulating this setup around the critical point. Critical points in statistical mechanics are incredibly interesting but real buggers to simulate. Fortunately there have been some very clever people who have worked out how to do this. I've not done anything that clever, but I have worked out how to implement a Wolff cluster algorithm using ~ N/4 bytes of memory which I think is good going.
I will post on this again when I've managed to run the programme on our fancy new computer (it's got 8GB of RAM) and have a nice picture to show. I will also explain what the Ising model is and what a critical point is...
Sunday, 16 November 2008
In other news I passed my viva! Hopefully this means I can start talking about statistical physics more which is sort of what I wanted to do with this blog in the first place.
Thursday, 6 November 2008
Wednesday, 29 October 2008
Saturday, 27 September 2008
I'm not an expert in anything related to health and I don't want this blog be about that so hopefully I'll only make this point once: What use is this sort of press release? I can't do anything with this information. The implication is that I should eat more meat, but there was no clinical trial so this is not justified. It reminds me of the research that said a glass of red wine was good for you based on a chemical that was in it. Trouble is there are other things in it as well and the evidence actually says that this isn't true (BS about this here but I warn there are some 'orrible pictures of tumours for no apparent reason).
EDIT: Here's the Oxford press release so you don't have to click the link...
Vitamin B12, a nutrient found in meat, fish and milk, may protect against brain volume loss in older people, according to a University of Oxford study.
For the study, 107 people between the ages of 61 and 87 underwent brain scans, memory testing and physical exams. The researchers from the Oxford Project to Investigate Memory and Ageing (OPTIMA) also collected blood samples to check vitamin B12 levels. Brain scans and memory tests were also performed again five years later.
The study, published in the journal Neurology, found that people who had higher vitamin B12 levels were six times less likely to experience brain shrinkage compared with those who had lower levels of the vitamin in their blood. None of the people in the study had vitamin B12 deficiency.
Many factors that affect brain health are thought to be out of our control, but this study suggests that simply adjusting our diets to consume more vitamin B12 through eating meat, fish, fortified cereals or milk may be something we can easily adjust to prevent brain shrinkage and so perhaps save our memory,” says Anna Vogiatzoglou of the Department of Physiology, Anatomy and Genetics at Oxford University. “Research shows that vitamin B12 deficiency is a public health problem, especially among the elderly, so more vitamin B12 intake could help reverse this problem. Without carrying out a clinical trial, we acknowledge that it is still not known whether B12 supplementation would actually make a difference in elderly persons at risk for brain shrinkage.”
Previous research on the vitamin has had mixed results and few studies have been done specifically with brain scans in elderly populations. We tested for vitamin B12 levels in a unique, more accurate way by looking at two certain markers for it in the blood,” adds Ms Vogiatzoglou.
Ms Vogiatzoglou says the study did not look at whether taking vitamin B12 supplements would have the same effect on memory.
The study was supported by the UK Alzheimer’s Research Trust, the Medical Research Council, the Charles Wolfson Charitable Trust, the Norwegian Foundation for Health and Rehabilitation through the Norwegian Health Association, Axis-Shield plc and the Johan Throne Holst Foundation for Nutrition Research.
Thesis is inches away from completion, I can smell the freedom already.
Sunday, 31 August 2008
Because that's what's always got on my nerves the most. Linux is a lot better than windows in many respects, but a lot worse in many others. The same goes for OS X. It depends what you're doing. Take my work for example: I'm a theoretical physicist and these days the majority of my work is numerical which means getting rather large computers to perform simulations of things rattling about, over and over and over again. All these big computers use Linux and so it's easier if your systems match. More than that though, Linux has a ton of software that is designed exactly for my needs, X-forwarding is great and its heavy use of the command line is much more efficient.
If you got into computers after Windows 95 and you don't like to fiddle under the bonnet then the chances are you won't ever use the command line. This isn't a shame in itself, it's up to you how you use your computer, but it's a shame that your choice is removed because the windows command prompt is so useless. Once you get going with a good command line interface it can make a real difference to your productivity (see for example Imagemagick).
So for work I'll (hopefully) never use Windows again. At home it's a different story. At home I use the web, edit photos and play music. Linux does all this but Windows has a better look and feel. Windows works better with my laptop's hardware (and peripharels) and there is a ton of good general software made for it. In my opinion its best bit of software is Windows Media Player. This is easily the best music player available (codec problems ruin the video playing). It's great for organising music, automatically finding artwork, creating playlists, quick search, seamless playback - the list goes on. It is infinitely better than the terrible iTunes. iTunes feels like it's actively trying to make me angry. I think it's designed to annoy you into only getting your music from the iTunes store. I'm constantly searching the net on how to get it to do this or that, WMP just does it.
Security is the top thing usually thrown at Windows. I go with the usual argument that it's just because there are more Windows PCs than anything else. Get complacent with your mac or Linux box and you'll wind up the same.
So what about the mac? Well Apple have been clever and maintained support for all things unixy (it is based on unix). This means that most of the good Linux features are supported, it does X11 so I can use most Linux programs, I can SSH into it (remote login) and so on. On top of this is has the better look and feel, it runs proprietary stuff like MS Office and it's got the best video chat facility by a mile. Apple (or maybe it's mac users themselves) always seem to be chipping away at improving the user interface. Things like exposé or Quicksilver are good examples. I'm very impressed with my iMac, it's a very neat piece of kit indeed.
Bad things about the mac are well documented. Hardware is expensive and exclusive, in many ways you're buying into a much worse monopoly than Microsoft. You won't be as compatible with everyone else (not a big deal these days), oh, and did I mention how much I hate iTunes? This shouldn't matter but Apple devotees tend to get on my nerves. I think there's a lot of fashion about owning a mac. They're always banging on the MS steal this or that. Honestly, get over yourselves. Everyone's iterating towards a better thing and Apple have reused plenty of ideas themselves (eg. spaces).
If I was buying a new laptop tomorrow I'd go for a mac. For me it covers the maximum amount of my daily stuff and I do like the interface. In general I would only recommend it if you know why you want to spend that bit more. I don't think Linux is ready to be my only OS just yet but I'll always run it on the side. The bottom line is they all do the job, they all crash (despite what people say), but most importantly of all they all run firefox so you won't really notice the difference most of the time.
Wednesday, 30 July 2008
He managed to give a good sense as to how much debate there is in the field. One thing everyone agrees on however, and where the article begins, is that cathedral windows do not sag because the glass has flowed.
"Medieval stained glass makers were simply unable to make perfectly flat panes, and the windows were just as unevenly thick when new."If you want something that does do that then let me point you in the direction of pitch, which drips about once a decade but shatters when hit with a hammer. So what is glass then? Is it a liquid or what?
Glass has the same structure as a liquid. If you take a photo you couldn't really tell the difference. A liquid that's on its way to being a glass, a supercool liquid, is the same as well. If instead of a photo you look at a video you'll see that it's actually really different. Weeks and company have actually done this and you can see regions really close to one another, some with lots of motion, some hardly moving at all. This is the dynamic heterogeneity, mentioned in the article, that goes along with the hugely increasing viscosity. Their website has loads of great stuff, including movies and a link to a freely available version of the Science paper, I recommend taking a look.
The region that I'm roughly poking about in at the moment is to do with vibrations and rigidity. This is touched on in the article a couple of times. Matthieu Wyart and others have spent a lot of time developing the idea of a glass as a marginally rigid solid (the introduction to Wyart's thesis is actually quite readable and freely accessible). It's looking at how the random liquid structure affects things at low temperatures.
Anyway, I'll leave it there. If I've missed any important links just stick them in a comment. Been a bit too busy writing my thesis to do this properly. Dear God let it end soon!
Wednesday, 23 July 2008
TFL try and sell this as something great for the commuters
We believe that this technology will enhance passengers' journeysReally? Are you sure it won't get on their nerves? Would you stop it if it did? The eventual aim is to have every pixel of your periphery flashing and shouting so that your brain is so confused with the unmanageable amount of information that you'll do anything they tell you. Or stumble in front of a train.
It's an inevitability, an arms race. If you cover every square inch in posters then, per square inch, they're all worth less. So to make your milliacre more valuable it must now move. Soon they will all move. Then they'll start shouting at you, then they'll get linked to your oyster card so they'll be calling your name. Worse, linked to your nectar card so they can chase you down the street offering you carefully selected products you might like.
Not everyone agrees with me: this advertising blogger thinks it's great and shows how hi-tech we are. TFL clearly like it. Anyone else? I'd really like to know.
I have the attention span of a pea. It takes nothing for me to lose track of what the hell I was thinking, what someone just said or even why I got on this train in the first place. Please, I'm begging, leave my poor brain alone!
Saturday, 19 July 2008
In this case the plausible statement is on the use of facebook, the internet, other such things. It even managed to be press released by the Royal College of Psychiatrists. This starts off
A generation of Internet users who have never known a world where you can't surf on-line may be growing up with a different and potentially dangerous view of the world and their own identity, according to a warning delivered to the Annual Meeting of the Royal College of Psychiatrists.Could be true. I wouldn't like to say. Things start to smell a little funny when they say
This is the age group involved with the Bridgend suicides and what many of these young people had in common was their use of Internet to communicate.OK stop there. Now I'm suspicious, don't all young people use the internet? By the way, the Bridgend suicides are also being blamed on mobile phone masts and, for all I know, computer games. In fact it feels like there is a rather sinister trend for untested/untestable claims to be applied to these tragic events, and why? Because it will get press attention. Without a doubt.
It seems that a horrible statistical fluctuation in the all-too-large distribution of teenage suicides is not a satisfying reason for the media or the public. And this leaves the door wide open for "experts" to fill the gap.
It's just too easy to say you think something is true and then press release to an unquestioning media. A classic example is the evolutionary psychology stuff (badscience has lots on this). These are the claims that we will split in to two distinct races or that we will evolve big willies. The papers just say that "Experts say..." washing themselves of responsibility. But who are these experts? Many of the proposals are plausible but that's not enough.
I could spend all day coming up with things that could be true. Unless it is testable then what use is it? Physicists come up with plausible theories all the time, but no one will get the nobel prize until it can be tested. The famous Feynman quote goes
"It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong."I appreciate that physics experiments are much easier (and by that I mean controlled) than social experiments, but that's no excuse for claiming you have the answer when all you have is a plausible explanation. It's a massively important distinction.
To anyone claiming to know the cause of the Bridgend suicides I beg you to think carefully; teenage suicide is a serious problem and they deserve much much better.
Edit: Here's the BBC coverage
Saturday, 5 July 2008
Supercooled water is just water that is below its freezing point but for one reason or another didn't crystalise. It's a form of metastable equilibrium. If you give it a big enough kick then it can escape and this happens
And you can do it with beer
If you keep cooling it further then you eventually get glass, and that's all glass is. Now my stuff is more interested on the supercooled goes to glass bit rather than freezing beer but you get the idea.
Friday, 27 June 2008
Firstly they did a track test comparing the prius against a BMW and found the BMW did better for mpg. This is something I've seen around and I'm certainly open to the fact that hybrids are beatable. They are, after all, just an attempt to make a petrol powered vehicle more efficient. I can't vouch for these tests though, from what I can gather they mostly seem to rely on motorway travel to beat the prius (which is best in the city).
The second thing though is completely contemptible of Clarkson. It's an old piece of bullshit that has been blogged about loads (badscience usually a good place to start) that the Prius is worse over its lifetime than a land rover (last time it was a hummer). I can't do a better job than has been done already, but it comes down to a dodgy report done by a marketing group. Now it's been broadcast on such a huge platform I doubt we'll ever here the end of it.
UPDATE: I think the dodge claim is about 45s in. http://youtube.com/watch?v=PP6fe6i1vaY
Tuesday, 24 June 2008
Right now I'm writing my thesis so I doubt I'll be putting much on here but when I do I suspect it'll mainly be based on the two things: physicsy stuff and statistics stuff. The former should be mainly positive (things I think are really interesting) and the latter will be mostly negative (ranting about stats-abuse). I guess we'll see how it goes.