Things I have learnt so far about AAAs

There are 6 books related to my project piled up on my desk at the moment. I spent about an hour in the main library yesterday. Today I spent about 3 hours in the medical library and another hour in the main library. I've found out quite a bit about aneurysms.

Off the top of my head I can inform anyone who might ask that aneurysms generally occur on the aorta (the main artery going from the heart that feeds oxygen and other good stuff to the body) and that they occur far more commonly in the abdominal region than in the thoracic region although they can form in both places at the same time.

When aneurysms form on the abdominal aorta they generally occur just below the renal arteries (arterial branches that feed the kidneys). There are several different types of aneurysm, but the fusiform type is the one which occurs most commonly in the abdominal aorta. Fusiform aneurysms are where the artery gets gradually wider and then thinner again rather than suddenly ballooning out on one side which would be a saccular aneurysm.

Abdominal aortic aneurysms are most likely to rupture once they reach a diameter of 6cm, but they can grow bigger in some cases. Then again, in other cases an abdominal aneurysm may rupture before it reaches a diameter of 6cm. 0.3% of ruptured abdominal aortic aneurysms occur when the aneurysm is less than 4cm in diameter though. The "normal" diameter of the aorta in the abdomen ranges from about 1.5cm to about 2.1cm. That depends on gender and a few other factors.

In general 3% of people get aneurysms, but if your parent has an aneurysm you are far more likely to develop an aneurysm than someone who is not related to anyone with an aneurysm.

The problem with abdominal aneurysms is that they rarely present with any symptoms at all. Most people who have them will not know about them unless they are screened. The problem with screening is that the most effective and most useful screening method is computed tomography (CT), which is rather expensive and a little time-consuming. It is debatable (and people are debating it) whether or not it is worth the money it would cost to screen all people who may be "at risk".

Generally it is older people (over 50) who develop aneurysms. Men are most at risk of developing an aneurysm, but females are more at risk of rupture according to many studies.

Seek and you shall find...

I have long been a believer that the internet knows everything, you just have to know how to find it. Google tends to help. Wikipedia is also pretty useful at times. However if you're not *quite* sure what you're looking for then the search is made that bit more difficult.

My supervisor advised me to do some reading about aneurysms and other medical things that are related, so that I can get my head round all the concepts. So I asked google and wikipedia about them. At first they told me some new and interesting information that I didn't know before, but then the trail dried up. Wikipedia wasn't as in-depth as I wanted to be. Somehow I had to find out how to get up to the next level.

It's like playing sonic the hedgehog. You know there's a magical level 10. But you're stuck in level one. Only you don't go up a level when you collect gold coins.

For years I've heard about "Athens". Not the one in ancient Greece, but the service for accessing some online journals for free if you're a student. The one in Aber was well advertised, but I never used it. The one here is reasonably well hidden away and I have very little idea about how on earth I should use it. Tonight I was determined though that I would find something useful.

After some searching on the uni library website I found a link to somewhere else where I searched for "aneurysm" and it spat out several reasonably useful articles. They're level 10 articles though and I don't understand all of the big long words.

Tomorrow various online dictionaries will get used in an effort to understand and learn something about aneurysms.

Sometimes I get frustrated by fortran!

I like FORTRAN. Really I do. I like creating programs that work and give me answers that mean things and that I can use to help me write reports and things for uni.

I have problems with it though. It took me ages to understand what I'm trying to do with my latest program. Creating a fortran program based on misunderstandings is never a good idea. I now have the concept though. I understand roughly what I'm trying to do.

The only thing is that now I know what I'm doing I can't figure out how to tell the computer the right fortran so that it will give me the desired answers.

My summer project

My project title is:
"Species (MMP) transport in an abdominal aortic aneurysm with a porous ILT."

A quick vocab guide might be of use to those who do not have a clue what that means...
MMPs are Matrix-metalloproteinases. I'm not entirely sure what they are, but I have a feeling they're tricky buggers.
An aneurysm is when your artery swells up like a balloon due to a problem in the artery wall (usually thinning caused either by age or by an accident). The aorta is the main artery going from your heart up and round and then down towards your legs. Aneurysms may rupture and when they do the chances of survival are not good. Abdominal aortic aneurysms are known as AAAs or Triple-As.
ILT is an Intraluminal Thrombus. A thrombus is a blood clot. Intraluminal means it's within a structure (so within the artery).
Hemodynamics is the study of the flow of blood.

Overall agreed objectives:

Write a medical review of AAAs including MMP influence.

Write a scientific review of AAAs including hemodynamics, experimental and computer models.

Develop a simple steady flow model of a AAA with a porous thrombus and mass transport.

Develop a simple pulsatile flow model of a AAA with a porous thrombus and mass transport.

Mesh a realistic model taken from segmented CT images.

Incorporate the simplified anatomical model developed above into the realistic anatomical model.

Analysis of interactions between the thrombus, blood, and the artery wall with respect to AAA progression.

Deliverable(s):
1. A simple CFD model of AAA mass transport in steady flow with a porous ILT.
2. A simple CFD model of AAA mass transport in pulsatile flow with a porous ILT.
3. A realistic model of AAA mass trans port in pulsatile flow with a porous ILT.
4. A project report

I'll be using ANSYS FLUENT to model the aneurysm in 2D and 3D. The 3D version will come from a CT scan from a real-live poorly person. I hope that they got patched up okay and are still alive.

I expect to be very busy this summer. The project is due to start at the beginning of June. Before then I am going to have to do some medical reading. I'm really excited about this project. It sounds really cool (and hard work) and interesting.

Some cool links and news

I got pointed to this YouTube video at the weekend, it is *really* cool and is the sort of thing that makes me sqwee about my subject. You should watch it because it has pretty lights and bouncing shampoo!

Another cool YouTube video is this one about ferro fluids. Ferro fluids are magnetic and... well watch the video and see for yourself what they do.

Today I read the news that my old uni is yet again doing something really cool now that I'm not there to see it. I missed their big show of venus passing in front of the sun about 3 years ago and now I'm missing the first ever 3D images of the sun. Traumatised I am!

That's all for the links for now, I'm incredibly busy with my MSc these days and don't get much time for thinking about any other maths stuff other than coursework and I don't really want to write about that any more than necessary. I do however have something to write about my upcoming summer project which should be a lot of fun, but also very hard work. Before I do that, however, I need rest and I need to do a little more research on it.

Foodstuffs that make me think of maths...

I see it as a true sign of a geek when someone sees their "area" of science/maths/engineering etc in things that they do/see in everyday life. This is one reason why I consider myself to be a maths geek.

When I make custard from scratch, I measure out the custard powder and the sugar. Then I pour in a drop of milk and stir. If there isn't enough milk for the powder then the spoon is really difficult to move. But if you take the spoon out and watch how the mixture moves on its own you can in fact see that at least part of it is a liquid because it's ever so slowly moving to the lowest point possible in the jug.

Recently I tried those Innocent smoothies for the first time. They are very nice to drink, but for a student they're rather expensive. Right now I'm at home for Easter and Mum has a blender, so I can make my own smoothies. It's amazing that you put solid fruit in and get liquid juice out. It's wonderful! It appeals to my inner geek.

Progress in CFX

Last term we did an introductory course for ANSYS CFX and I found it really interesting. ANSYS CFX is a computer package with which you can design an object, then create a mesh to cover it (imagine a spider's web stretched over the object) and then you can set parameters and things and tell it to model what would happen if water came in one end, air through the top and there was just one outlet pipe (for example). Then as if by magic the program thinks about it for a while and gives you an answer.

Well now we have to do some coursework using it, it's not due until May and today I started it finally. I've been trying to start it for the past 4 weeks now, but all my attempts have been thwarted by the problem of a locked door. There is just one room in the whole university that has CFX computers in apparently and as CFD Masters students we are allowed to go in there. Only the door is always locked. It took two weeks to ascertain who was going to be allowed to give us permission to go in there. Then that person was off sick, then he was in meetings for most of last week. Well today I caught up with his secretary again and found out that the room is meant to be unlocked in office hours and that we can go in whenever we want, so long as there isn't a class in progress. Hurrah!

So I spent an hour or so playing with a piece of software I learnt a little bit about 3 months ago and haven't been able to touch since. On my third attempt I managed to complete the basic design for the object we were told to create. I meshed it first time without any problems. Then I tried to open it in what they call the Pre-Processor. I failed. It's got the wrong file extension and I have no idea how to convert it to the correct one. I can't recall that we were ever told how to go from meshing to pre. This is frustrating. I'm hoping that someone else in my class knows and can show me later in the week. This should not be a problem considering we're now allowed in the room Mon-Fri, 9am-5pm.