A Hamiltonian model is constructed for the spin axis of a planet perturbed by a nearby planet with both planets in orbit about a star. We expand the planet-planet gravitational potential perturbation to first order in orbital inclinations and eccentricities, finding terms describing spin resonances involving the spin precession rate and the two planetary mean motions. Convergent planetary migration allows the spinning planet to be captured into spin resonance. With initial obliquity near zero, the spin resonance can lift the planet's obliquity to near 90 or 180 degrees depending upon whether the spin resonance is first or zero-th order in inclination. Past capture of Uranus into such a spin resonance could give an alternative non-collisional scenario accounting for Uranus's high obliquity. However we find that the time spent in spin resonance must be so long that this scenario cannot be responsible for Uranus's high obliquity. Our model can be used to study spin resonance in satellite systems. Our Hamiltonian model explains how Styx and Nix can be tilted to high obliquity via outward migration of Charon, a phenomenon previously seen in numerical simulations.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7485118 | PMC |
| http://dx.doi.org/10.1007/s10569-017-9804-6 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Compressed SENSE acceleration factor influence on magnetic resonance image quality in patients with endometrial cancer.
Phys Med
January 2025
Center for Radiology, University Clinical Center of Vojvodina, Hajduk Veljkova 1-9, 21000 Novi Sad, Serbia; Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia. Electronic address:
Objectives: To investigate the impact of compressed sensing - sensitivity encoding (CS-SENSE) acceleration factor on the diagnostic performance of magnetic resonance imaging (MRI) within standard female pelvis protocol in patients with endometrial cancer.
Methods: T2-weighted turbo spin echo (TSE) sequence from standard female pelvic MRI protocol was chosen due to its long acquisition time and essential role in the evaluation of morphological characteristics of the female pelvic anatomical structures. Fully sampled reference scans and multiple prospectively 2x to 5x under-sampled CS-SENSE scans were acquired.
Motion-Compensated Multishot Pancreatic Diffusion-Weighted Imaging With Deep Learning-Based Denoising.
Invest Radiol
January 2025
From the Department of Radiology, Stanford University, Stanford, CA (K.W., M.J.M., A.M.L., A.B.S., A.J.H., D.B.E., R.L.B.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA (K.W.); GE HealthCare, Houston, TX (X.W.); GE HealthCare, Boston, MA (A.G.); and GE HealthCare, Menlo Park, CA (P.L.).
Objectives: Pancreatic diffusion-weighted imaging (DWI) has numerous clinical applications, but conventional single-shot methods suffer from off resonance-induced artifacts like distortion and blurring while cardiovascular motion-induced phase inconsistency leads to quantitative errors and signal loss, limiting its utility. Multishot DWI (msDWI) offers reduced image distortion and blurring relative to single-shot methods but increases sensitivity to motion artifacts. Motion-compensated diffusion-encoding gradients (MCGs) reduce motion artifacts and could improve motion robustness of msDWI but come with the cost of extended echo time, further reducing signal.
View Article and Find Full Text PDFDefects Calculation and Accelerated Interfacial Charge Transfer in a Photoactive MOF-Based Heterojunction.
Small
January 2025
Institutes of Physical Science and Information Technology, Anhui Graphene Carbon Fiber Materials Research Center, Anhui University, Hefei, Anhui, 230601, P. R. China.
Photocatalytic hydrogen production is currently considered a clean and sustainable route to meet the energy and environmental issues. Among, heterojunction photocatalysts have been developed to improve their photocatalytic efficiency. Defect engineering of heterojunction photocatalysts is attractive due to it can perform as electron trap and change the band structure to optimize the interfacial separation rate of photogenerated electron-hole pairs.
View Article and Find Full Text PDFMultiparametric MRI Assessment of Morpho-Functional Muscle Changes Following a 6-Month FES-Cycling Training Program: Pilot Study in People With a Complete Spinal Cord Injury.
JMIR Rehabil Assist Technol
January 2025
Istituto di Sistemi e Tecnologie Industriali Intelligenti per il Manifatturiero Avanzato, Consiglio Nazionale delle Ricerche, via Alfonso Corti, 12, Milan, 20133, Italy, 39 02 2369 993.
Background: Spinal cord injuries (SCIs) cause debilitating secondary conditions such as severe muscle deterioration, cardiovascular, and metabolic dysfunctions, significantly impacting patients' quality of life. Functional electrical stimulation (FES) combined with cycling exercise (FES-cycling) has shown promise in improving muscle function and health in individuals with SCI.
Objective: This pilot study aimed to investigate the potential role of multiparametric magnetic resonance imaging (MRI) to assess muscle health during and after an FES-cycling rehabilitation program.
Ab Initio Rotational and Vibrational Spectroscopy of CH Radicals at the Coupled Cluster Level.
J Phys Chem A
January 2025
Department of Chemistry, University of California, Davis, One Shields Ave., Davis, California 95616, United States.
Combustion and pyrolysis processes of allene and propyne are known to involve radicals with the structural formula CH, the most stable of which is the classic resonance-stabilized allyl radical. In addition to allyl, four other isomers of CH are possible: the propene derivatives -1-propenyl, -1-propenyl, and 2-propenyl, as well as the cyclopropane derivative cyclopropyl. Among these 5 species, the allyl radical has been extensively studied both theoretically and spectroscopically; however, little is known about the spectroscopy of the cyclopropyl radical, and virtually no experimental spectroscopic data are available for the remaining three.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!