Wednesday, October 16, 2013
Thursday, October 10, 2013
Er, thanks(?) to former BSL postdoc Yiemeng Hoi for sending me this depressing story about the ugly side of open-access publishing: http://scicomm.scimagdev.org/.
Not that traditional journals are exempt. There are simply too many journals, and good peer-reviewers are overworked, meaning that a lot of stuff gets relegated to potentially unqualified reviewers. And the pressure to publish N papers per year has led to a "let's throw it at the wall and see if it sticks" attitude to journal article submission. Science suffers from all of this noise, and we have only ourselves to blame for falling into the bibliometric trap set for us by the bean-counters.
Which makes me wonder. Should I review articles from groups I know and trust to be careful and honest, and nit pick their papers to make sure they are rock solid and bullet-proof? Or should I spend time instead reviewing for lesser journals and novice authors, where the reviewer is implicitly being asked to teach the authors how to write a paper, to make sure that crap doesn't inadvertently make it into the system?
I never know what is the embargo policy for specific journals, but since the printer has delayed the processing of our paper (accepted almost three months ago), I think it's fair that we share the good/bad news about a study led by BSL postdoc Kristian Valen-Sendstad, entitled: "Mind the gap: Impact of CFD solution strategy on prediction of intracranial aneurysm hemodynamics and rupture status indicators". Here's the abstract, paper (hopefully) coming soon:
Materials and Methods: Pulsatile flow in 12 realistic MCA aneurysms was simulated using both high resolution (HR) and normal resolution (NR) strategies. Velocity fields were compared at selected instants via domain-averaged error. Wall shear stress (WSS) fields and various reduced hemodynamic indices were also compared: cycle-averaged mean and maximum WSS; oscillatory shear index (OSI); low shear area (LSA); viscous dissipation ratio (VDR); kinetic energy ratio (KER).
Results: Instantaneous differences in flow and WSS patterns were appreciable, especially for bifurcation aneurysms. Linear regressions revealed strong correlations (R2>0.9) between HR and NR solutions for all indices but KER (R2=0.25) and OSI (R2=0.23); however, for most indices the slopes were significantly less than one, reflecting a pronounced underestimation by the NR simulations. Some HR simulations were highly unstable with fluctuating WSS, reflected by the poor OSI correlation.
Conclusion: Typical CFD solution strategies may ultimately be adequate for augmenting rupture risk assessment based on certain highly-reduced indices; however, they cannot be relied upon for predicting the magnitude and character of the complex biomechanical stimuli to which the aneurysm wall may be exposed. This impact of CFD solution strategy is likely greater than that for other modelling assumptions or uncertainties.
Labels: BSL publications