Classes have been hogging my attention lately, generating a lot of reading and homework. I have hardly touched my research projects in a month. Today I got the ball rolling again, completing a few “Next Actions” from each project.
It felt great.
It’s nice that, with GTD, I can just jump back into my projects as if they were the only thing that has been on my mind.
After years of hearing, “lower fat, lower fat” from dieticians, a new authoratative study finds that a diet low in fat doesn’t decrease your chances of heart disease or cancer (if you’re female). I lost my weight by reducing refined sugars and flour… I never really paid attention to fat content.
Chances a low-fat diet will help? Slim and none – Health & Science – International Herald Tribune
The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect.
For the past few weeks, I’ve made Wednesday “Article Review” day. I’ll still post reviews that I deem pertinent on other days, but the goal is to post one each Wednesday at a minimum.
The Hubmed page for today’s article is here: Unpinning of a Rotating Wave in Cardiac Muscle by an Electric Field by Alain Pumir and Valentin Krinsky
Tachycardia (fast heart beat) is commonly caused by a rotating wave of activation in the heart. The study of rotating waves of this type has years of legacy in theoretical and chemical dynamics studies. Today’s article covers rotating waves pinned to anatomical obstacles such as valve openings in the heart. Rotating waves circle a core, which can be functional (a property of the wave shape and dynamics) or anatomical (an obstacle). In the case of an anatomical obstacle, the wave can be eliminated by ablation, which is commonly used in the atria, electrical defibrillation, or possibly unpinning / antitachycardia pacing (ATP). Ablation is typically invasive, requiring catheterization, and defibrillation requires an external shock, or surgery to implant an ICD. Defibrillation, either externally or internally, damages the heart, is painful, and often causes loss of consciousness. Antitachycardia pacing and electrical unpininning open the possibility of elimination of tachycardia with small shocks.
The principle of electrical unpinning, proposed by Huyet et al. (1998) and Krinsky et al. (1995), is that when a localized stimulus is applied in a certain part of the wave tail, it may move the core of the rotating wave. It’s difficult to place a stimulus in a particular place at a particular time in a patient’s heart, but it turns out that when an electrical field is applied over an obstacle, areas of depolarization (positive change) and hyperpolarization (negative change) manifest on the borders of the obstacle.
The paper by Pumir and Krinsky details how a small electrical field may be applied at a specific timing relative to wave rotation in order to create such a depolarization on an obstacle that will unpin a wave attached to that same obstacle. They used simplified models of cardiac action potentials, including the Beeler-Reuter and Fitzhugh models. Since the method deals with the dynamics of a spiral wave, and not with particulars of ionic currents, it’s a safe bet that the methods will apply in more complex models and cardiac tissue.
I won’t repeat the article’s simple and logical explanation of how it works — go read it. It’s only 9 pages, the figures are clear, and the math is mercifully simplified in a way that (ostensibly) doesn’t undermine the results.
As the newish tagline of my blog indicates, I’m a practitioner of David Allen’s Getting Things Done (GTD). I’ve been meaning to make some posts about how I apply it to graduate school and research, but in the mean time, Matthew Cornell has a nice post about warning signs that you’re not keeping things out of your head and in the system.
Matt’s Idea Blog: Some GTD warning signs
I’ve occasionally noticed some signs of falling behind. I wanted to share a few of them, and ask what others you’ve come across in your implementation.
These are also good signs that you might need to revamp your organization, even if you’re not a GTD practitioner per se.
I came across this blog via one of my Technorati keyword watchlists. The parent site/company, Ion Channel Media Group, was a bit hard to figure out from just their website. According to the CEO, who was kind enough to reply to my inquiring email, the company does, “citation analysis to create alerts for researchers in specific life sciences fields. We use this information to produce a number of portals and then sell advertising, email marketing and PR campaigns.”
It’s curious, to be sure. Nonetheless, the blog looks pretty interesting, and the latest article covers something I was going to do a complete post on — the recent scandals over fraudulent scientific research. There are also some interesting stories on electrophysiology — automatic patch clamping and the like. It’s probably worth checking out if you follow electrophysiology, but I find the whole site/company/webring a bit strange.
fresh research in biomedical science – from Ion Channel Media Group