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Archive for December, 2010

Winter of Code

Creek in December

IT HAS been a week or so since I last made a research-related post, so here is a quick update. I am currently coding some bits that can detect and measure rotation in the heart, including tangential/centrifugal components. The goal is to calculate the twist and also the scale changes separately, giving a figure indicative of each. The notions found in flow/vortex mathematics ought to enable this to be calculated from a set (or matrix) of points, each of which being a vector of directions around a central point. To quote Wikipedia on vortex: “A vortex (plural: vortices) is a spinning, often turbulent, flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex. The speed and rate of rotation of the fluid in a free (irrotational) vortex are greatest at the center, and decrease progressively with distance from the center, whereas the speed of a forced (rotational) vortex is zero at the center and increases proportional to the distance from the center. Both types of vortices exhibit a pressure minimum at the center, though the pressure minimum in a free vortex is much lower.”

My implementation of this is simplistic as it merely uses an accumulator whose value increases for each point that moves in a given direction (e.g. for each clockwise arrow) and decreases for the opposite.

An issue we face here is that circular motion in the heart walls is far from trivial to see. A careful look at image sequences taken with about 20 frames for each cycle and each slice does not quite expose a ‘squeeze’ of the heart, not unless there is tagging of the image which also enables reconstruction of a higher quality. So, to calculate rotation of the sides based on just intensity is rather hard, unless there is something in the signal that can be detected. Generally, looking at the tracking typically carried out, there is hardly a tendency to pick up any traces of tangential motion and where it does exist it is not consistent. Assuming a direction is known and then estimated with a probabilistic model, there is room for improvement, maybe even a significant change in contrast. Different slices show different directions for the twist and it requires a look inside the heart too, in order to visually compare intensities and assume a rotation of some sort. I will post some images soon to illustrate this.

Additional code was completed to calculate and plot the centre of the points around the heart, based on the fitting of a circle to all the surrounding points (best match). At the end of each tracking sequence a plot if shown to give a statistical analysis of how points move around the walls and whether they move in and out throughout the cardiac cycle. The goal here is to, based on several cycle, find out if and how the algorithm can detect wall motion and quantify it. There is clearly a correlation to be found here.

Today’s addition (it’s a holiday, so lots of spare time for coding and also to read literature) will soon be uploaded along with more material, all of which will be shared not just for the sake of transparency. I’ll post results shortly.

As a side note, I’ve begun looking into the possibility of writing a book about Novell and another possibility I’m looking into is initiating a startup around the code I’ve been writing since 2003 to achieve something nobody achieved before, even with free/libre software (the whole stack). I’m currently doing cardiac analysis but still considering a situation where come back to a more CS-oriented work, at least when the existing contract is over. There are many projects on my mind and choosing just the best one/s is not easy. Then again, it’s good to have possibilities and I’m still in my twenties, so there is no pressure.

TechBytes 21: Hello Dolly, Trolls, Boosters, and Advocates

TechBytes

Direct download as Ogg (1:25:51, 25.6 MB) | Direct download as MP3 (39.3 MB)

Summary: Tim, Gordon, and Roy speak about many different topics including the show itself

TODAY’S show was covering many topics and OpenBytes has published the show notes.

RSS 64x64Today’s show ends with “Harold T Wilkins” by Fanfarlo (from SXSW 2009 Showcasing Artists). We hope you will join us for future shows and consider subscribing to the show via the RSS feed. You can also visit our archives for past shows. If you have an Identi.ca account, consider subscribing to TechBytes in order to keep up to date.

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Transparency

Transparency can be a way of life to those who wish to expose what they are doing. Since 2002 when I built this Web site I have made many aspects of my life public and this did not cause much trouble at all. Transparency leads to a state where there are no secrets and thus there is little room for scandals or mischief. Last night I was challenged by a friend to whom my preference of transparency seemed inadequate. This is fine. Well, more and more people willingly become more transparent over time (sadly in Web sites like Facebook which exploit them) and their eagerness to share personal material is proving infectious. Governments too are starting to find out that sooner or later data which they keep secret will leak and Neelie Kroes rightly pointed out that Wikileaks/Cablegate will push more governments toward becoming transparent.

Transparency breeds trust. Secrecy breeds misconduct.

Contour and Arrows

Contour and arrows

The animated figure below shows how contouring is done with a new and improved algorithm in place. The sequence is show in reverse, as the window titles help indicate. Arrows can be put on top of the contour to signal the direction of movement of each landmark point, but arrow can in general add clutter and it may be worth taking a group of several points and study based on these the direction of movement of entire region, then display fewer large arrows.

Contour and gradient

TechBytes on GNU/Linux Gaming

TechBytes

Direct download as Ogg (1:03:24, 18.6 MB) | Direct download as MP3 (29.0 MB)

Summary: Tim and Roy speak about some recent news and discuss the world of GNU/Linux gaming

TODAY’S show was covering games for GNU/Linux and to some degree phones running Linux as well. We left our discussion about trolls and lobbying to tomorrow’s show and OpenBytes will have published the show notes by then (it’s late now in the UK).

RSS 64x64Today’s show ends with “Paper Gown” by Caroline Herring (from SXSW 2009 Showcasing Artists). We hope you will join us for future shows and consider subscribing to the show via the RSS feed. You can also visit our archives for past shows. If you have an Identi.ca account, consider subscribing to TechBytes in order to keep up to date.

As embedded (HTML5):

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GNU/Linux Market and Mono – TechBytes Debate

TechBytes

Direct download as Ogg (1:12:39, 21.6 MB) | Direct download as MP3 (33.3 MB)

Summary: A few hot topics from the past few days are debated and we also make a mention of Mono proponents

TODAY’S show was a short one as it was not scheduled and erratic work schedule harmed our regular pace. Gordon was absent, but he will be back in the next show. OpenBytes has published the show notes just now.

RSS 64x64Today’s show ends with “Plastic Cans” by Underwater Tea Party. We hope you will join us for future shows and consider subscribing to the show via the RSS feed. You can also visit our archives for past shows. If you have an Identi.ca account, consider subscribing to TechBytes in order to keep up to date.

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Episode 18 on Google, Fog Computing, and Digital Freedoms

TechBytes

Direct download as Ogg (1:59:08, 36.1 MB) | Direct download as MP3 (54.5 MB)

Summary: After almost a week (due to absence) we return to covering and debating recent stories of relevance within our scope

TODAY’S show covers many topics ranging from Google’s new operating system to Microsoft’s slow death in the mobile space. OpenBytes has published the show notes containing some of the topics we ran through.

RSS 64x64Today’s show ends with “Devil’s Best Dress” by Cord Lund. We hope you will join us for future shows and consider subscribing to the show via the RSS feed. You can also visit our archives for past shows. If you have an Identi.ca account, consider subscribing to TechBytes in order to keep up to date.

As embedded (HTML5):

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