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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Toy Blocks And Rotational Physics, Gabriele U. Varieschi, Isabel R. Jully
Toy Blocks And Rotational Physics, Gabriele U. Varieschi, Isabel R. Jully
Gabriele Varieschi
Have you ever observed a child playing with toy blocks? A favorite game is to build towers and then make them topple like falling trees. To the eye of a trained physicist this should immediately look like an example of the physics of “falling chimneys,” when tall structures bend and break in mid-air while falling to the ground. The game played with toy blocks can actually reproduce well what is usually seen in photographs of falling towers, such as the one that appeared on the cover of the September 1976 issue of The Physics Teacher.1 In this paper we describe …
Toy Models For The Falling Chimney, Gabriele U. Varieschi, Kaoru Kamiya
Toy Models For The Falling Chimney, Gabriele U. Varieschi, Kaoru Kamiya
Gabriele Varieschi
In this paper we review the theory of the ‘‘falling chimney,’’ which deals with the breaking in mid-air of tall structures when they fall to the ground. We show that these ruptures can be caused by either shear forces typically developing near the base, or by the bending of the structure which is caused primarily by the internal bending moment. In the latter case the breaking is more likely to occur between one-third and one-half of the height of the chimney. Small scale toy models are used to reproduce the dynamics of the falling chimney. By examining photos taken during …
Random Field Disorder At An Absorbing State Transition In One And Two Dimensions, Hatem Barghathi, Thomas Vojta
Random Field Disorder At An Absorbing State Transition In One And Two Dimensions, Hatem Barghathi, Thomas Vojta
Physics Faculty Research & Creative Works
We investigate the behavior of nonequilibrium phase transitions under the influence of disorder that locally breaks the symmetry between two symmetrical macroscopic absorbing states. In equilibrium systems such "random-field" disorder destroys the phase transition in low dimensions by preventing spontaneous symmetry breaking. In contrast, we show here that random-field disorder fails to destroy the nonequilibrium phase transition of the one- and two-dimensional generalized contact process. Instead, it modifies the dynamics in the symmetry-broken phase. Specifically, the dynamics in the one-dimensional case is described by a Sinai walk of the domain walls between two different absorbing states. In the two-dimensional case, …
Yoyo Lab (Prelab), David Abbott
Yoyo Lab (In-Lab), David Abbott
Rate Kinetics And Molecular Dynamics Of The Structural Transitions In Amyloidogenic Proteins, Timothy Michael Steckmann
Rate Kinetics And Molecular Dynamics Of The Structural Transitions In Amyloidogenic Proteins, Timothy Michael Steckmann
FIU Electronic Theses and Dissertations
Amyloid fibril aggregation is associated with several horrific diseases such as Alzheimer’s, Creutzfeld-Jacob, diabetes, Parkinson’s and others. The process of amyloid aggregation involves forming myriad different metastable intermediate aggregates. Amyloid fibrils are composed of proteins that originate in an innocuous α-helix or random-coil structure. The α-helices convert their structure to β-strands that aggregate into β-sheets, and then into protofibrils, and ultimately into fully formed amyloid fibrils. On the basis of experimental data, I have developed a mathematical model for the kinetics of the reaction pathways and determined rate parameters for peptide secondary structural conversion and aggregation during the entire fibrillogenesis …