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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Cosmological Initial Data For Numerical Relativity, David Garfinkle, Lawrence Mead
Cosmological Initial Data For Numerical Relativity, David Garfinkle, Lawrence Mead
Faculty Publications
© 2020 American Physical Society. We find initial data for numerical relativity simulations of inhomogeneous cosmologies. This involves treating an exceptional case of the general relativity constraint equations. We devise analytic and numerical methods to treat this exceptional case. We apply the analytic method to the standard case of cosmology with a single scalar field. The numerical method is applied to the two-field ekpyrotic cosmology.
The Search For Microbial Martian Life And American Buddhist Ethics, Daniel S. Capper
The Search For Microbial Martian Life And American Buddhist Ethics, Daniel S. Capper
Faculty Publications
Multiple searches hunt for extraterrestrial life, yet the ethics of such searches in terms of fossil and possible extant life on Mars have not been sufficiently delineated. In response, in this essay I propose a tripartite ethic for searches for microbial Martian life that consists of default nonharm toward potential living beings, default nonharm to the habitats of potential living beings, but also responsible, restrained scientific harvesting of some microbes in limited transgression of these default nonharm modes. Although this multifaceted ethic remains secular and hence adaptable to space research settings, it arises from both a qualitative analysis of authoritative …
Galileo's Telescope, Christopher Sirola
Galileo's Telescope, Christopher Sirola
Faculty Publications
One of the most consequential inventions of modern times is the telescope. Almost immediately upon turning it to the skies, Galileo made discoveries that altered our perceptions of our place in the cosmos forever: features on the Moon, the rotation of the Sun, the composition of the Milky Way, the phases of Venus, and the four large moons of Jupiter.
The Shape Of The Orbit In Flrw Spacetimes, David Garfinkle, Lawrence R. Mead, H.I. Ringermacher
The Shape Of The Orbit In Flrw Spacetimes, David Garfinkle, Lawrence R. Mead, H.I. Ringermacher
Faculty Publications
The shape of the orbit of a free particle is examined in Friedmann-Lemaître-Robertson-Walker (FLRW) cosmologies. The spatial projection of the orbit is time-independent and has a simple geometric description. We relate this description to the expression in terms of standard FLRW coordinates.
May The Forces Be With You!, Christopher Sirola
May The Forces Be With You!, Christopher Sirola
Faculty Publications
In everyday life, we usually directly note two basic forces: gravity and electromagnetism. Gravity—as in the acceleration due to Earth’s gravity—tends to be a background force of sorts, something that is always present and always the same. We don’t always see electricity and/or magnetism as such, but their subsidiaries are all around us—friction, normal force, tension, springs, and the like.
Relativistic Three-Dimensional Lippman-Schwinger Cross Sections For Space Radiation Applications, Charles M. Werneth, Xiaojing Xu, Ryan B. Norman, Khin M. Maung
Relativistic Three-Dimensional Lippman-Schwinger Cross Sections For Space Radiation Applications, Charles M. Werneth, Xiaojing Xu, Ryan B. Norman, Khin M. Maung
Faculty Publications
Radiation transport codes require accurate nuclear cross sections to compute particle fluences inside shielding materials. The Tripathi semi-empirical reaction cross section, which includes over 60 parameters tuned to nucleon-nucleus (NA) and nucleus-nucleus (AA) data, has been used in many of the world’s best-known transport codes. Although this parameterization fits well to reaction cross section data, the predictive capability of any parameterization is questionable when it is used beyond the range of the data to which it was tuned. Using uncertainty analysis, it is shown that a relativistic three-dimensional Lippmann-Schwinger (LS3D) equation model based on Multiple Scattering Theory (MST) that uses …
Model-Independent Plotting Of The Cosmological Scale Factor As A Function Of Lookback Time, H. I. Ringermacher, L. R. Mead
Model-Independent Plotting Of The Cosmological Scale Factor As A Function Of Lookback Time, H. I. Ringermacher, L. R. Mead
Faculty Publications
In this work we describe a model-independent method of developing a plot of scale factor a(t) versus lookback time tL from the usual Hubble diagram of modulus data against redshift. This is the first plot of this type. We follow the model-independent methodology of Daly & Djorgovski used for their radio-galaxy data. Once the a(t)data plot is completed, any model can be applied and will display as described in the standard literature. We then compile an extensive data set to z = 1.8 by combining Type Ia supernovae (SNe Ia) data from SNLS3 …
Biofunctionalization And Immobilization Of A Membrane Via Peptide Binding (Cr3-1, S2) By A Monte Carlo Simulation, Ras B. Pandey, Hendrik Heinz, Jie Feng, Barry L. Farmer
Biofunctionalization And Immobilization Of A Membrane Via Peptide Binding (Cr3-1, S2) By A Monte Carlo Simulation, Ras B. Pandey, Hendrik Heinz, Jie Feng, Barry L. Farmer
Faculty Publications
A coarse-grained computer simulation model is used to study the immobilization of a dynamic tethered membrane (representation of a clay platelet) in a matrix of mobile peptide chains CR3-1:(1)Trp-(2)Pro-(3)Ser-(4)Ser-(5)Tyr-(6)Leu-(7)Ser-(8)Pro-(9)Ile-(10)Pro-(11)Tyr-(12)Ser and S2:(1)His-(2)Gly-(3)Ile-(4)Asn-(5)Thr-(6)Thr-(7)Lys-(8)Pro-(9)Phe-(10)Lys-(11)Ser-(12)Val on a cubic lattice. Each residue interacts with the membrane nodes with appropriate interaction and executes their stochastic motion with the Metropolis algorithm. Density profiles, binding energy of each residue, mobility, and targeted structural profile are analyzed as a function of peptide concentration. We find that the binding of peptides S2 is anchored by lysine residues ((7)Lys,(10)Lys) while peptides CR3-1 do not bind to membrane. The membrane slows down …
Globular Structure Of A Human Immunodeficiency Virus-1 Protease (1difa Dimer) In An Effective Solvent Medium By A Monte Carlo Simulation, Ras B. Pandey, Barry L. Farmer
Globular Structure Of A Human Immunodeficiency Virus-1 Protease (1difa Dimer) In An Effective Solvent Medium By A Monte Carlo Simulation, Ras B. Pandey, Barry L. Farmer
Faculty Publications
A coarse-grained model is used to study the structure and dynamics of a human immunodeficiency virus-1 protease (1DIFA dimer) consisting of 198 residues in an effective solvent medium on a cubic lattice by Monte Carlo simulations for a range of interaction strengths. Energy and mobility profiles of residues are found to depend on the interaction strength and exhibit remarkable segmental symmetries in two monomers. Lowest energy residues such as Arg(41) and Arg(140) (most electrostatic and polar) are not the least mobile; despite the higher energy, the hydrophobic residues (Ile, Leu, and Val) are least mobile and form the core by …