Article Information

• PDF (644 kb)
• Full Text with Thumbnail Figures
• Full Text with Large Figures
• Supplemental Data

PubMed

• Articles by Erin F. Baerwald
• Articles by Robert M.R. Barclay

Related Articles

• Turbine troubles

  Turbine troubles Current Biology, Volume 16, Issue 16, 22 August 2006, Pages R618 Nigel Williams Summary reports on some of the emerging ecological problems with wind farms. Summary | Full Text | PDF (91 kb)

• Centriole Assembly: The Origin of Nine-ness

  Centriole Assembly: The Origin of Nine-ness Current Biology, Volume 17, Issue 24, 18 December 2007, Pages R1057-R1059 Wallace F. Marshall Summary Recent studies of the mutant have revealed that the ninefold symmetry of the centriole is set by the length of the cartwheel spokes, which fixes the diameter, and thereby the circumference, of the centriole. Summary | Full Text | PDF (106 kb)

• Bacterial Flagellar Microhydrodynamics: Laminar Flow over Co...

  Bacterial Flagellar Microhydrodynamics: Laminar Flow over Complex Flagellar Filaments, Analog Archimedean Screws and Cylinders, and Its Perturbations Biophysical Journal, Volume 85, Issue 3, 1 September 2003, Pages 1345-1357 Shlomo Trachtenberg, Dalia Fishelov and Matania Ben-Artzi Abstract The flagellar filament, the bacterial organelle of motility, is the smallest rotary propeller known. It consists of 1), a basal body (part of which is the proton driven rotary motor), 2), a hook (universal joint—allowing for off-axial transmission of rotary motion), and 3), a filament (propeller—a long, rigid, supercoiled helical assembly allowing for the conversion of rotary motion into linear thrust). Helically perturbed (so-called “complex”) filaments have a coarse surface composed of deep grooves and ridges following the three-start helical lines. These surface structures, reminiscent of a turbine or Archimedean screw, originate from symmetry reduction along the six-start helical lines due to dimerization of the flagellin monomers from which the filament self assembles. Using high-resolution electron microscopy and helical image reconstruction methods, we calculated three-dimensional density maps of the complex filament of H13-3 and determined its surface pattern and boundaries. The helical symmetry of the filament allows viewing it as a stack of identical slices spaced axially and rotated by constant increments. Here we use the closed outlines of these slices to explore, in two dimensions, the hydrodynamic effect of the turbine-like boundaries of the flagellar filament. In particular, we try to determine if, and under what conditions, transitions from laminar to turbulent flow (or perturbations of the laminar flow) may occur on or near the surface of the bacterial propeller. To address these questions, we apply the boundary element method in a manner allowing the handling of convoluted boundaries. We tested the method on several simple, well-characterized cylindrical structures before applying it to real, highly convoluted biological surfaces and to simplified mechanical analogs. Our results indicate that under extreme structural and functional conditions, and at low Reynolds numbers, a deviation from laminar flow might occur on the flagellar surface. These transitions, and the conditions enabling them, may affect flagellar polymorphism and the formation and dispersion of flagellar bundles—factors important in the chemotactic response. Abstract | Full Text | PDF (371 kb)

• …more

Summary

Bird fatalities at some wind energy facilities around the world have been documented for decades, but the issue of bat fatalities at such facilities — primarily involving migratory species during autumn migration — has been raised relatively recently [1,2]. Given that echolocating bats detect moving objects better than stationary ones [3], their relatively high fatality rate is perplexing, and numerous explanations have been proposed [1]. The decompression hypothesis proposes that bats are killed by barotrauma caused by rapid air-pressure reduction near moving turbine blades [1,4,5]. Barotrauma involves tissue damage to air-containing structures caused by rapid or excessive pressure change; pulmonary barotrauma is lung damage due to expansion of air in the lungs that is not accommodated by exhalation. We report here the first evidence that barotrauma is the cause of death in a high proportion of bats found at wind energy facilities. We found that 90% of bat fatalities involved internal haemorrhaging consistent with barotrauma, and that direct contact with turbine blades only accounted for about half of the fatalities. Air pressure change at turbine blades is an undetectable hazard and helps explain high bat fatality rates. We suggest that one reason why there are fewer bird than bat fatalities is that the unique respiratory anatomy of birds is less susceptible to barotrauma than that of mammals.