We analyze the locomotor behavior of the rat during exploration, and show that digitally collected data (time series of positions) provide a sufficient basis for establishing that the rat uses several distinct modes of motion (first, second, third, and sometimes fourth gear). The distinction between these modes is obtained by first segmenting the time series into sequences of data points occurring between arrests (as ascertained within the resolution of the data acquisition system). The statistical distribution of the maximal amount of motion occurring within each of these episodes is then analyzed and shown to be multi modal. This enables us to decompose motion into distinct modes. In one application of this decomposition we show that the ethological ad hoc notion of stopping behavior corresponds to progression without leaving first gear. We do so by showing that the spatial spread of such progressions is confined to a small 20-50 cm range in a 6.5 m diameter arena. This provides a justification for a construct of 'staying in place'. This construct is not defined in terms of position in objective space, but purely in terms of the rat's own behavior. We test the generality of our method by applying it to mouse exploratory behavior.
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http://dx.doi.org/10.1016/s0165-0270(99)00194-6 | DOI Listing |
Phys Chem Chem Phys
March 2025
School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA.
Hydrogen storage as hydrates is one of the most environmentally benign approaches to store hydrogen as it requires only water and traces of promoters. However, the scalability of storing hydrogen hydrate formation is hindered by the limited understanding of the structure, dynamics and energetics of hydrogen and promoters in the hydrate cages. In this study, molecular dynamics simulation configurations with different occupancy modes of H and tetrahydrofuran (THF) in the hydrate cages are investigated under the following scenarios: (i) two H molecules occupying the small cages, (ii) occupancy of H molecules in the THF-free large cages, and (iii) co-occupancy of H and THF in one large cage.
View Article and Find Full Text PDFJ Phys Chem B
March 2025
Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR), Area della Ricerca, Via G. Moruzzi 1, Pisa I-56124, Italy.
In this contribution, we present a computational study on the absorption and emission spectra of the anion in water, an analogue of the firefly oxyluciferin phenolate keto form. This compound displays a broad absorption spectrum and a large Stokes shift, two features that remain elusive to computational approaches, preventing a complete understanding of the photophysics behind this molecule. Here we attempt a fully first-principles computation of both absorption and emission spectral shapes and positions, explicitly including the effect of soft molecular flexible modes and of the stiff vibrational motions as well as those of the solvent.
View Article and Find Full Text PDFPhotoacoustics
April 2025
College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.
Imaging speed is critical for photoacoustic microscopy as it affects the capability to capture dynamic biological processes and support real-time clinical applications. Conventional approaches for increasing imaging speed typically involve high-repetition-rate lasers, which pose a risk of thermal damage to samples. Here, we propose a deep-learning-driven optical-scanning undersampling method for photoacoustic remote sensing (PARS) microscopy, accelerating imaging acquisition while maintaining a constant laser repetition rate and reducing laser dosage.
View Article and Find Full Text PDFOf the 1.5 million emergency room visits each year in the United States due to flexor tendon injuries in the hand, over 30-40% result in peritendinous adhesions which can limit range of motion (ROM) and severely impact an individual's quality of life. Adhesions are fibrous scar-like tissues which can form between adjacent tissues in the body in response to injury, inflammation, or during normal healing following surgery.
View Article and Find Full Text PDFSci Rep
March 2025
CEA.DES.IRESNE.DEC, Cadarache F 13108, St Paul Lez Durance, France.
In addition to being the most used nuclear fuel, uranium dioxide is a superionic conductor like some battery materials, for which molecular dynamic calculations evidenced string-like collective motion that exists in glass forming materials. Its simple crystalline structure and the development of up to date dedicated modeling makes UO a prototypical material for the study of anharmonic dynamic that lies underneath its specific properties. In this paper, the analysis of two specific phonons modes by empirical potential calculation led us to the identification of UO high temperature phase transition as Fm-3m to Pa-3 first order transition.
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