The analysis of undulatory swimming gaits requires knowledge of the fluid forces acting on the animal body during swimming. In his classical 1952 paper, Taylor analysed this problem using a 'resistive-force' theory. The theory was used to characterize the undulatory gaits that result in the smallest energy dissipation to the fluid for a given swim velocity. The optimal gaits thus found were compared with data recorded from movies of a snake and a leech swimming. This report identifies and corrects a mathematical error in Taylor's paper, showing that his theory applies even better to animals of circular cross section.
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http://dx.doi.org/10.1098/rsif.2009.0568 | DOI Listing |
Annu Rev Clin Psychol
January 2025
1Massachusetts Veterans Epidemiology Research and Information Center, VA Boston Healthcare System, Boston, Massachusetts, USA.
Moral injury (MI) is a potential clinical problem characterized by functionally impairing moral emotions, beliefs, and behaviors as well as adverse beliefs about personal or collective humanity and life's meaning and purpose. MI can arise from personal transgressive acts or from being a victim of or bearing witness to others' inhumanity. Despite widespread interest in MI, until recently, there was no reliable measure of MI as an outcome, and prior research has revealed little about its causes, consequences, and intervention approaches.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Institute for Computational Physics, University of Stuttgart, Allmandring 3, Stuttgart 70569, Germany.
The constant-pH Monte Carlo method is a popular algorithm to study acid-base equilibria in coarse-grained simulations of charge regulating soft matter systems including weak polyelectrolytes and proteins. However, the method suffers from systematic errors in simulations with explicit ions, which lead to a symmetry-breaking between chemically equivalent implementations of the acid-base equilibrium. Here, we show that this artifact of the algorithm can be corrected a-posteriori by simply shifting the pH-scale.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
We present a hybrid semiempirical density functional tight-binding (DFTB) model with a machine learning neural network potential as a correction to the repulsive term. This hybrid model, termed machine learning tight-binding (MLTB), employs the standard self-consistent charge (SCC) DFTB formalism as a baseline, enhanced by the HIP-NN potential as an effective many-body correction for short-range pairwise repulsive interactions. The MLTB model demonstrates significantly improved transferability and extensibility compared to the SCC-DFTB and HIP-NN models.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Qingdao Institute for Theoretical and Computational Sciences and Center for Optics Research and Engineering, Shandong University, Qingdao 266237, China.
Given a number of data sets for evaluating the performance of single reference methods for the low-lying excited states of closed-shell molecules, a comprehensive data set for assessing the performance of multireference methods for the low-lying excited states of open-shell systems is still lacking. For this reason, we propose an extension (QUEST#4X) of the radical subset of QUEST#4 ( , , 3720) to cover 110 doublet and 39 quartet excited states. Near-exact results obtained by iterative configuration interaction with selection and second-order perturbation correction (iCIPT2) are taken as benchmark to calibrate static-dynamic-static configuration interaction (SDSCI) and static-dynamic-static second-order perturbation theory (SDSPT2), which are minimal MRCI and CI-like perturbation theory, respectively.
View Article and Find Full Text PDFJAMA Netw Open
January 2025
Laboratory of NeuroImaging, National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland.
Importance: Cannabis use has increased globally, but its effects on brain function are not fully known, highlighting the need to better determine recent and long-term brain activation outcomes of cannabis use.
Objective: To examine the association of lifetime history of heavy cannabis use and recent cannabis use with brain activation across a range of brain functions in a large sample of young adults in the US.
Design, Setting, And Participants: This cross-sectional study used data (2017 release) from the Human Connectome Project (collected between August 2012 and 2015).
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