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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
First-Principles Calculated Decomposition Pathways For Libh4 Nanoclusters, Zhi-Quan Huang, Wei-Chih Chen, Feng-Chuan Chuang, Eric Majzoub, Vidvuds Ozoliņš
First-Principles Calculated Decomposition Pathways For Libh4 Nanoclusters, Zhi-Quan Huang, Wei-Chih Chen, Feng-Chuan Chuang, Eric Majzoub, Vidvuds Ozoliņš
Physics Faculty Works
We analyze thermodynamic stability and decomposition pathways of LiBH4 nanoclusters using grand-canonical free-energy minimization based on total energies and vibrational frequencies obtained from density-functional theory (DFT) calculations. We consider (LiBH4)n nanoclusters with n = 2 to 12 as reactants, while the possible products include (Li)n, (B)n, (LiB)n, (LiH)n, and Li2BnHn; off-stoichiometric LinBnHm (m ≤ 4n) clusters were considered for n = 2, 3, and 6. Cluster ground-state configurations have been predicted using prototype electrostatic ground-state (PEGS) and genetic algorithm (GA) based structural optimizations. Free-energy calculations show hydrogen release pathways markedly differ from those in bulk LiBH4. While experiments have found …
Wormhole Geometries In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi, Kellie L. Ault
Wormhole Geometries In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi, Kellie L. Ault
Physics Faculty Works
We present an analysis of the classic wormhole geometries based on conformal Weyl gravity, rather than standard general relativity. The main characteristics of the resulting traversable wormholes remain the same as in the seminal study by Morris and Thorne, namely, that effective super-luminal motion is a viable consequence of the metric. Improving on previous work on the subject, we show that for particular choices of the shape and redshift functions the wormhole metric in the context of conformal gravity does not violate the main energy conditions at or near the wormhole throat. Some exotic matter might still be needed at …
Frame-Invariant Proper-Force, Phil Fraundorf
Frame-Invariant Proper-Force, Phil Fraundorf
Physics Faculty Works
Here we try to find “the best joints for carving up” the phenomenon of accelerated-motion so as to obtain (i)the least need for extended-networks of synchronized-clocks as well as (ii) the greatest frame-independence.The acceleration four-vector’s invariant magnitude, and a number of other quantities from the traveler’spoint of view, show promise for broadening student understanding (and perhaps even practical application)of accelerated motion perspectives at both low and high speeds.
En Route To Destruction: The Evolution In Composition Of Ices In Comet D/2012 S1 (Ison) Between 1.2 And 0.34 Au From The Sun As Revealed At Infrared Wavelengths, M. Disanti, B. Bonev, E. Gibb, L. Paganini, G. Villanueva, M. Mumma, J. Keane, G. Blake, N. Russo, K. Meech, R. Vervack, A. Mckay
En Route To Destruction: The Evolution In Composition Of Ices In Comet D/2012 S1 (Ison) Between 1.2 And 0.34 Au From The Sun As Revealed At Infrared Wavelengths, M. Disanti, B. Bonev, E. Gibb, L. Paganini, G. Villanueva, M. Mumma, J. Keane, G. Blake, N. Russo, K. Meech, R. Vervack, A. Mckay
Physics Faculty Works
We report production rates for H2O and eight trace molecules (CO, C2H6, CH4, CH3OH, NH3, H2CO, HCN, C2H2) in the dynamically new, Sun-grazing Comet C/2012 S1 (ISON), using high-resolution spectroscopy at Keck II and the NASA IRTF on 10 pre-perihelion dates encompassing heliocentric distances Rh = 1.21–0.34 AU. Measured water production rates spanned two orders of magnitude, consistent with a long-term heliocentric power law Q(H2O) ${\rm{\propto }}{R}_{{\rm{h}}}^{(-3.1\pm 0.1)}$. Abundance ratios for CO, C2H6, and CH4 with respect to H2O remained constant with Rh and below their corresponding mean values measured among a dominant sample of Oort Cloud comets. CH3OH was …
Chimera States In A Hodgkin-Huxley Model Of Thermally Sensitive Neurons, Tera Glaze, Scott Lewis, Sonya Bahar
Chimera States In A Hodgkin-Huxley Model Of Thermally Sensitive Neurons, Tera Glaze, Scott Lewis, Sonya Bahar
Physics Faculty Works
Chimera states occur when identically coupled groups of nonlinear oscillators exhibit radically different dynamics, with one group exhibiting synchronized oscillations and the other desynchronized behavior. This dynamical phenomenon has recently been studied in computational models and demonstrated experimentally in mechanical, optical, and chemical systems. The theoretical basis of these states is currently under active investigation. Chimera behavior is of particular relevance in the context of neural synchronization, given the phenomenon of unihemispheric sleep and the recent observation of asymmetric sleep in human patients with sleep apnea. The similarity of neural chimera states to neural “bump” states, which have been suggested …
Black Hole Shadows In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi, Jonas Mureika
Black Hole Shadows In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi, Jonas Mureika
Physics Faculty Works
We calculate the characteristics of the “black hole shadow” for a rotating, neutral black hole in fourth-order conformal Weyl gravity. It is shown that the morphology is not significantly affected by the underlying framework, except for very large masses. Conformal gravity black hole shadows would also significantly differ from their general relativistic counterparts if the values of the main conformal gravity parameters, γ and κ, were increased by several orders of magnitude. Such increased values for γ and κ are currently ruled out by gravitational phenomenology. Therefore, it is unlikely that these differences in black hole shadows will be detected …