Andrew F. Loftus, Sigrid Noreng, Vivian L. Hsieh, and Raghuveer Parthasarathy, "Robust Measurement of Membrane Bending Moduli Using Light Sheet Fluorescence Imaging of Vesicle Fluctuations," Langmuir 29: 14588–14594 (2013). [Link]
Alexander R. Small and Raghuveer Parthasarathy,
"Superresolution Localization Methods,"
Annual Review of Physical Chemistry (2013 -- online ahead of print).
Abstract: Superresolution localization microscopy methods produce nanoscale images via a combination of intermittently active fluorescent probes and algorithms that can precisely determine the positions of these probes from single-molecule or few-molecule images. These algorithms vary widely in their underlying principles, complexity, and accuracy. In this review, we begin by surveying the principles of localization microscopy and describing the fundamental limits to localization precision. We then examine several different families of fluorophore localization algorithms, comparing their complexity, performance, and range of applicability (e.g., whether they require particular types of experimental information, are optimized for specific situations, or are more general). Whereas our focus is on the localization of single isotropic emitters in two dimensions, we also consider oriented dipoles, three-dimensional localization, and algorithms that can handle overlapping images of several nearby fluorophores. Throughout the review, we try to highlight practical advice for users of fluorophore localization algorithms, as well as open questions.
Matthew Jemielita*, Michael J. Taormina*, April DeLaurier, Charles B. Kimmel, and Raghuveer Parthasarathy (*Equal authors), "Comparing phototoxicity during the development of a zebrafish craniofacial bone using confocal and light sheet fluorescence microscopy techniques," J. Biophotonics 6: 920-928 (2013). [Link]
Andrew F. Loftus, Vivian Hsieh, and Raghuveer Parthasarathy,
"Modulation of membrane rigidity by the human vesicle trafficking proteins Sar1A and Sar1B,"
Biophys. Biochem. Res. Comm. 426: 585-589 (2012). Link
"Rapid, accurate particle tracking by calculation of radial symmetry centers," Nature Methods
9: 724-726 (2012), DOI: 10.1038/nmeth.2071 .
Abstract: I introduce an algorithm for sub-pixel localization of imaged objects based on an analytic, non-iterative calculation of the best-fit radial symmetry center. This approach yields tracking accuracies that are near theoretical limits, similar to Gaussian fitting, but with orders of magnitude faster execution time, lower sensitivity to nearby particles, and applicability to any radially symmetric intensity distribution. I demonstrate the method with several types of data, including super-resolution microscopy images.
Also: There's an associated News and Views article (by Alex Small).
Michael J. Taormina, Matthew Jemielita, W. Zac Stephens, Adam R. Burns, Joshua V. Troll, Raghuveer Parthasarathy, and Karen Guillemin, "Investigating Bacterial-Animal Symbioses with Light Sheet Microscopy," Biol. Bulletin 223: 7-20 (2012). (Part of a special issue on "Discoveries in Animal Symbiosis in the 'omics' Age," August 2012.) [Link]
Emily Goers Sweeney, J. Nathan Henderson, John Goers, Christopher Wreden, Kevin G. Hicks, Jeneva K. Foster,
Raghuveer Parthasarathy, S. James Remington, and Karen Guillemin,
"Structure and Proposed Mechanism for the pH-Sensing Helicobacter pylori Chemoreceptor TlpB," Structure
2012 (online publication date: June 14, 2012). DOI: http://dx.doi.org/10.1016/j.str.2012.04.021 .
Cover art: My artwork for this paper is on the cover of the July issue of Structure. -- RP
Raghuveer Parthasarathy, "Cars and Kinetic Energy - Some Simple Physics with Real-World Relevance," The Physics Teacher 50: 395-397 (2012). [Link]
[Book Chapter] Raghuveer Parthasarathy, "Optics: Basic Physics," in Handbook of Biomedical Optics, ed. D.A. Boas, C. Pitris, N. Ramanujam (CRC Press, 2011). [Link]
[Retracted] Christopher W. Harland, Miranda J. Bradley, and Raghuveer Parthasarathy,
"Phospholipid bilayers are viscoelastic," Proc. Natl. Acad. Sci. USA
107: 19146-19150 (2010). Link
The conclusions of this paper are wrong -- a consequence of insufficiently precise analysis. Our retraction notice
was published in August 2011; you can read the page proof here or a version with graphs
(not allowed in the official retraction notice) here. We deeply regret any confusion
or wasted effort caused by our flawed paper, and we are happy to provide additional information or resources on technical issues related to the paper's methods.
A postscipt: Spurred by these events, I've been thinking about whether there can exist a particle tracking method that is as accurate as direct fitting of Gaussian intensity profiles to particle images (the present state-of-the-art) but that is computationally much faster. I have come up with a new sort of tracking, based on maximizing radial symmetry, that works well. For a very brief description, see here. For a longer discussion and tests of the method, see my 2012 Nature Methods paper noted above, and my Particle Tracking page. -- RP.
Edward I. Settles*, Andrew F. Loftus*, Alesia N. McKeown, and Raghuveer Parthasarathy, "The vesicle trafficking protein Sar1 lowers lipid membrane rigidity," Biophys. J. 99: 1539-1545 (2010). [* = equal contributors] [ Link]
[Preview / Commentary paper; not a peer-reviewed article] Anica M. Wandler, Raghuveer Parthasarathy, and Karen Guillemin, "A greasy foothold for Helicobacter pylori," Cell Host & Microbe 7: 338-339 (2010). [Link] [PubMed]
Yupeng Kong and Raghuveer Parthasarathy, "Different modulation mechanisms of attractive colloidal interactions by lipid and protein functionalization," Langmuir 26: 10541-10545 (2010). [Link]
Kamil Godula, Marissa L. Umbel, David Rabuka, Zsofia Botyanszki, Carolyn R. Bertozzi, and Raghuveer Parthasarathy, "Control of the molecular orientation of membrane-anchored biomimetic glycopolymers," J. Am. Chem. Soc. 131: 10263-10268 (2009). [Link] See also the cover of Nature Chemical Biology, July 2010: Journal link, a bigger image with some text, and a better description.
Yupeng Kong and Raghuveer Parthasarathy, "Modulation of attractive colloidal interactions by lipid membrane functionalization," Soft Matter, 5: 2027-2029 (2009) [Link]
Christopher W. Harland*, Zsofia Botyanszki*, David Rabuka, Carolyn R. Bertozzi, and Raghuveer Parthasarathy, "Synthetic trehalose glycolipids confer desiccation resistance to supported lipid monolayers," Langmuir 25: 5193-5198, (2009) [*These authors contributed equally to this work][Link], [PMC Link]
Gregory T. Tietjen, Yupeng Kong, and Raghuveer Parthasarathy "An efficient method for the creation of tunable optical line traps via control of gradient and scattering forces," Opt. Express 16: 10341-10348 (2008) [Link]
Christopher W. Harland, David Rabuka, Carolyn R. Bertozzi, and Raghuveer Parthasarathy. "The M. tuberculosis virulence factor trehalose dimycolate imparts desiccation resistance to model mycobacterial membranes," Biophys. J. 94: 4718-4724 (2008). [Link]
Jay T. Groves, Raghuveer Parthasarathy, and Martin B. Forstner, "Fluorescence Imaging of Membrane Dynamics," Annu. Rev. Biomed. Eng. 10: 311-338 (2008). [Link]
Raghuveer Parthasarathy, David Rabuka, Carolyn Bertozzi, and Jay T. Groves, "Molecular Orientation of Membrane-Anchored Mucin Glycoprotein Mimics, J. Phys. Chem. B, 111: 12133-12135 (2007). [ACS]
David Rabuka, Raghuveer Parthasarathy, Goo Soo Lee, Xing Chen, Jay T. Groves, and Carolyn Bertozzi, "Hierarchical Assembly of Model Cell Surfaces: Synthesis of Mucin Mimetic Polymers and Their Display on Supported Bilayers," J. Amer. Chem. Soc., 129: 5462-5471 (2007). [ACS]
Raghuveer Parthasarathy, Cheng-han Yu, and Jay T. Groves, "Curvature modulated phase separation in lipid bilayer membranes," Langmuir, 22: 5095-5099 (2006). [ACS]
Raghuveer Parthasarathy and Jay T. Groves, "Coupled membrane fluctuations and protein mobility in supported intermembrane junctions," J. Phys. Chem. B, 110: 8513-8516 (2006). [ACS]
Raghuveer Parthasarathy, Paul A. Cripe, and Jay T. Groves, "Electrostatically Driven Spatial Patterns in Lipid Membrane Composition," Phys. Rev. Lett. 95: 048101 (2005). [PubMed]
Raghuveer Parthasarathy and Jay T. Groves, "Protein Patterns at Lipid Bilayer Junctions," Proc. Natl. Acad. Sci. 101: 12798-12803 (2004). [PubMed]
Raghuveer Parthasarathy and Jay T. Groves, "Optical techniques for imaging membrane topography," Cell Biochem. Biophys. 41: 391-414 (2004). [PubMed]
Raghuveer Parthasarathy, Bryan L. Jackson, Thomas J. Lowery, Amy P. Wong, and Jay T. Groves, "Nonequilibrium Adhesion Patterns at Lipid Bilayer Junctions," J. Phys. Chem. B 108: 649-657 (2004). [ACS]
Xiao-Min Lin, Raghuveer Parthasarathy, and Heinrich M. Jaeger, "Nanocrystal Arrays: Self-assembly and physical properties," in the Dekker Encoclyopedia of Nanoscience and Nanotechnology, ed. J.A. Schwarz, C.I. Contescu, K. Putyera (Dekker, 2004).
Thomas Scheibel, Raghuveer Parthasarathy, George Sawicki, Xiao-Min Lin, Heinrich Jaeger, and Susan L. Lindquist, "Conducting nanowires built by controlled self-assembly of amyloid fibers and selective metal deposition," Proc. Natl. Acad. Sci. 100: 4527-4532 (2003). [PNAS]
Raghuveer Parthasarathy, Xiao-Min Lin, and Heinrich M. Jaeger,
"Electronic transport in metal
nanocrystal arrays: the effect of structural disorder on scaling behavior,"
Phys. Rev. Lett. 87: 186807 (2001).
Xiao-Min Lin, Raghuveer Parthasarathy, and Heinrich M. Jaeger, "Direct patterning of self-assembled nanocrystal monolayers by electron beams," Appl. Phys. Lett. 78: 1915-1917 (2001). [Link]
H. M. Rønnow, R. Parthasarathy, J. Jensen, G. Aeppli, T. F. Rosenbaum, and D. F. McMorrow, "Quantum phase transition of a magnet in a spin bath," Science 308: 389-392 (2005). [Link]
S. Ghosh, R. Parthasarathy, T. F. Rosenbaum, and G. Aeppli, "Coherent spin oscillations in a disordered magnet," Science 296: 2195-2198 (2002). [Link]
S. Anders, R. Parthasarathy, H. M. Jaeger, P. Guptasarma, D. G. Hinks, and R. van Veen, "Dynamics of the second peak in the magnetization of Bi2Sr2CaCu2O8 crystals," Phys. Rev. B 58: 6639-6644 (1998).
D. H. Cobden, G. Pilling, R. Parthasarathy, P. L. McEuen, I. M. Castleton, E. H. Linfield, D. A. Ritchie, and G. A. C. Jones, "Current flow past an etched barrier: field emission from a two-dimensional electron gas," Europhys. Lett. 41: 327-332 (1998).
R. Parthasarathy, C. Franck, R. Treffers,
D. Cudaback, C. Heiles, C. Hancox, and R. Millan, "A rooftop radio
observatory: an undergraduate telescope system at the University of
California at Berkeley," Am. J. Phys. 66: 768-771 (1998).