Linear and nonlinear counter-traveling waves in a fluid-filled annular cylinder with realistic no-slip boundary conditions uniformly heated from below and rotating about a vertical axis are investigated. When the gap of the annular cylinder is moderate, there exist two three-dimensional traveling waves driven by convective instabilities: a retrograde mode localized near the outer sidewall and a prograde mode adjacent to the inner sidewall with a different wave number, frequency and critical Rayleigh number. It is found that the retrogradely propagating mode is always more unstable and is marked by a larger azimuthal wave number. When the Rayleigh number is sufficiently large, both the counter-traveling modes can be excited and nonlinearly interacting, leading to an unusual nonlinear phenomenon in rotating Rayleigh-Bénard convection.
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http://dx.doi.org/10.1103/PhysRevE.77.027301 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637.
Many proteins form paralogous multimers-molecular complexes in which evolutionarily related proteins are arranged into specific quaternary structures. Little is known about the mechanisms by which they acquired their stoichiometry (the number of total subunits in the complex) and heterospecificity (the preference of subunits for their paralogs rather than other copies of the same protein). Here, we use ancestral protein reconstruction and biochemical experiments to study historical increases in stoichiometry and specificity during the evolution of vertebrate hemoglobin (Hb), an αβ heterotetramer that evolved from a homodimeric ancestor after a gene duplication.
View Article and Find Full Text PDFSports Med Open
January 2025
Department of Mechanical Engineering, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul, 04107, Republic of Korea.
Background: Knee valgus loading is thought to be an important contributor to noncontact anterior cruciate ligament (ACL) injuries, but the effects of training programs focusing on decreasing knee valgus loading on lower extremity biomechanics with respect to ACL injury risk remain unclear. Thus, this study aimed to examine the effect of strength training designed to strengthen the medial thigh muscles on lower extremity joint kinematics, kinetics and muscle activity during single-leg landing.
Methods: A total of 35 healthy participants randomly conducted either exercises targeting medial thigh muscles (intervention group) or exercises that did not target specific lower extremity muscles (control group).
Chemistry
January 2025
Indian Institute of Technology Madras, Department of Chemistry, Chennai, Chennai, INDIA.
A series of significantly bulky mono- and di-substituted cyclic alkyl-amino carbene (cAAC)- functionalized cyclopentadiene ring (Cp) compounds were synthesized. The functionalization of the Cp ring with cAAC ligands makes them significantly bulkier, while retaining their ligation properties. These compounds display interesting fluorescence properties.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2.
Rigid, conjugated molecules are excellent candidates as molecular wires since they can achieve full extension between electrodes while maintaining conjugation. Molecular design can be used to minimize the accessible pi surface and interactions between the bridging wire and the electrode. Polyynes are archetypal molecular wires that feature a rigid molecular framework with a cross-section of a single carbon atom.
View Article and Find Full Text PDFJ Cell Biol
April 2025
Department of Physics and Astronomy, University of Denver, Denver, CO, USA.
In the early Drosophila embryo, germband elongation is driven by oriented cell intercalation through t1 transitions, where vertical (dorsal-ventral aligned) interfaces contract and then resolve into new horizontal (anterior-posterior aligned) interfaces. Here, we show that contractile events produce a continuous "rectification" of cell interfaces, in which interfaces systematically rotate toward more vertical orientations. As interfaces rotate, their behavior transitions from elongating to contractile regimes, indicating that the planar polarized identities of cell-cell interfaces are continuously re-interpreted in time depending on their orientation angle.
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