785 research outputs found
Metastable Knots in Confined Semiflexible Chains
No full textWe study the size distribution of spontaneous knots on semiflexible chains confined in square cross-section channels using Monte Carlo simulations. The most probable knot size, i.e. the metastable knot size, is found to vary nonmonotonically with the channel size. In the case of weak confinement, the metastable knot size is larger than the knot size in bulk because the segments within the knot feel less channel confinement than the segments outside the knot, and the channel pushes the segments into knot cores to reduce the overall free energy. Conversely, in the case of strong confinement, the metastable knot size is smaller than the one in bulk because the segments within the knot experience more channel confinement, and the channel expels segments from the knot core. We demonstrate that a simple theory can capture this nonmonotonic behavior and quantitatively explain the metastable knot size as a function of the channel size. These results may have implications for tuning the channel size to either generate or screen knots.Singapore. National Research Foundation (Singapore-MIT Alliance for Research and Technology)National Science Foundation (U.S.) (Grant CBET-1335938
New Zealand's threatened bryophytes: Conservation efforts
No full textFife, Allan J., Glenny, David, Beever, Jessica E., Braggins, John E., Brownsey, Patrick J., Renner, Matthew A.M., Hitchmough, Rod (2010): New Zealand's threatened bryophytes: Conservation efforts. Phytotaxa 9: 275-278, DOI: 10.11646/phytotaxa.9.1.1
AR-Glasses-Based Attention Guiding for Complex Environments - Requirements, Classification and Evaluation
No full textRenner P, Pfeiffer T. AR-Glasses-Based Attention Guiding for Complex Environments - Requirements, Classification and Evaluation. In: The 13th PErvasive Technologies Related to Assistive Environments Conference (PETRA '20). ACM; 2020
Enhanced electrohydrodynamic collapse of DNA due to dilute polymers
Get PDFWe experimentally demonstrate that addition of small, charge-neutral polymers to a buffer solution can promote compression of dilute solutions of single electrophoresing DNA. This phenomenon contrasts with the observed extension of DNA during capillary electrophoresis in dilute solutions of high molecular weight polymers. We propose these discrepancies in micron-scale DNA configurations arise from different nano-scale DNA-polymer collision events, controlled by solute polymer properties. We build upon theories previously proposed for intermolecular DNA aggregation in polymer-free solutions to develop scaling theories that describe trends seen in our data for intramolecular DNA compaction in dilute polymer solutions.National Science Foundation (U.S.) (Grant 1335938)Singapore. National Research Foundation (Singapore-MIT Alliance for Research and Technology
Relational Analysis of the Frauchiger–Renner Paradox and Interaction-Free Detection of Records from the Past
No full textWe present an analysis of the Frauchiger–Renner Gedankenexperiment from the point of view of the relational interpretation of quantum mechanics. Our analysis shows that the paradox obtained by Frauchiger and Renner disappears if one rejects promoting one agent’s certainty to another agent’s certainty when it cannot be validated by records from the past. A by-product of our analysis is an interaction-free detection scheme for the existence of such records.Analysi
Metastable Tight Knots in Semiflexible Chains
Get PDFKnotted structures can spontaneously occur in polymers such as DNA and proteins, and the formation of knots affects biological functions, mechanical strength and rheological properties. In this work, we calculate the equilibrium size distribution of trefoil knots in linear DNA using off-lattice simulations. We observe metastable knots on DNA, as predicted by Grosberg and Rabin. Furthermore, we extend their theory to incorporate the finite width of chains and show an agreement between our simulations and the modified theory for real chains. Our results suggest localized knots spontaneously occur in long DNA and the contour length in the knot ranges from 600 to 1800 nm.National Science Foundation (U.S.) (NSF Grant No. 1335938)Singapore. National Research FoundationSingapore-MIT Alliance for Research and Technology (SMART
Untying Knotted DNA with Elongational Flows
Get PDFWe present Brownian dynamics simulations of initially knotted double-stranded DNA molecules untying in elongational flows. We show that the motions of the knots are governed by a diffusion–convection equation by deriving scalings that collapse the simulation data. When being convected, all knots displace nonaffinely, and their rates of translation along the chain are topologically dictated. We discover that torus knots “corkscrew” when driven by flow, whereas nontorus knots do not. We show that a simple mechanism can explain a coupling between this rotation and the translation of a knot, explaining observed differences in knot translation rates. These types of knots are encountered in nanoscale manipulation of DNA, occur in biology at multiple length scales (DNA to umbilical cords), and are ubiquitous in daily life (e.g., hair). These results may have a broad impact on manipulations of such knots via flows, with applications to genomic sequencing and polymer processing.Singapore-MIT Alliance for Research and Technology (SMART)National Science Foundation (U.S.) (Grant CBET-1335938
Federic G. Renner with Mitchell Wilder at the Amon Carter Museum of Western Art
No full textImage of Frederic G. Renner of Washington, author of the catalog for the exhibition of Russell Illustrated letters. Mr. Renner is photographed having a conversation with Mitchell Wilder, director of the museum. The two men are photographed looking at the Russell letters. Fort Worth Star-Telegram Evening edition January 23, 1962.https://mavmatrix.uta.edu/specialcollections_startelegram1960s/1735/thumbnail.jp
Amon Carter Museum of Western Art; Frank Wardlaw, with Frederic G. Renner Johnson II
No full textFrank Wardlaw, director of the University of Texas Press, left, discusses a Russell bronze with Frederic G. Renner, author of Charles M. Russell: Paintings, Drawings and Sculpture in the Amon G. Carter Collection. Renner was honored at a reception in Amon Carter Museum of Western Art. Fort Worth Star-Telegram Morning edition September 27, 1966.https://mavmatrix.uta.edu/specialcollections_startelegram1960s/3395/thumbnail.jp
THE DOUBLE RENNER EFFECT IN A TRIATOMIC MOLECULE
No full textAuthor Institution: FB 9 - Theoretische Chemie, Bergische Universit\""{a}t; Department of Chemistry, Faculty of Science, Ochanomizu UniversityThe electronic energy of a triatomic molecule can be doubly degenerate at linear configurations but split into two non-degenerate components at bent geometries. This is termed the Renner effect. If two different linear geometries are accessible to the molecule and the electronic energy is doubly degenerate at these geometries, we speak about the `double Renner effect.' For example, a double Renner effect will occur if the triatomic molecule ABC isomerizes between two linear minima ABC and BCA, say, and the electronic energy is doubly degenerate at these minima. An example of this is afforded by the two isomers MgNC and MgCN in the electronic state. Also ABB molecules can exhibit the double Renner effect. In the and electronic states of HOO, the proton orbits the OO moiety with two equivalent minima on each potential surface at bent geometries. At the two linear geometries HOO and OOH (which correspond to maxima on the potential energy surface) the two electronic states are degenerate as a state. The two equivalent minima on each surface are separated by a maximum corresponding to a T-shaped geometry. We have developed a program for calculating the rovibronic energies for a triatomic molecule in `double-Renner'-degenerate electronic states. Our program can treat both ABC- and ABB-type molecules. The new program has been applied to MgNC/MgCN, and to HOO in the and states. We present detailed analyses of rotation-bending-electronic wavefunctions aimed at providing further insight into the nature of the double-Renner interaction
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