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- Conformal gravity (2)
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Articles 1 - 15 of 15
Full-Text Articles in Physical Sciences and Mathematics
Astrophysical Tests Of Kinematical Conformal Cosmology In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi
Astrophysical Tests Of Kinematical Conformal Cosmology In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi
Physics Faculty Works
In this work we analyze kinematical conformal cosmology (KCC), an alternative cosmological model based on conformal Weyl gravity (CG), and test it against current type Ia supernova (SNIa) luminosity data and other astrophysical observations. Expanding upon previous work on the subject, we revise the analysis of SNIa data, confirming that KCC can explain the evidence for an accelerating expansion of the Universe without using dark energy or other exotic components. We obtain an independent evaluation of the Hubble constant, H0 = 67:53 kms-1 Mpc-1, very close to the current best estimates. The main KCC and CG parameters are …
On Axiomatic Definitions Of Non-Discrete Affine Buildings, Curtis D. Bennett, Petra N. Schwer, Koen Struyve
On Axiomatic Definitions Of Non-Discrete Affine Buildings, Curtis D. Bennett, Petra N. Schwer, Koen Struyve
Mathematics Faculty Works
In this paper we prove equivalence of sets of axioms for non-discrete affine buildings, by providing different types of metric, exchange and atlas conditions. We apply our result to show that the definition of a Euclidean building depends only on the topological equivalence class of the metric on the model space. The sharpness of the axioms dealing with metric conditions is illustrated in an appendix. There it is shown that a space X defined over a model space with metric d is possibly a building only if the induced distance function on X satisfies the triangle inequality.
Kerr Metric, Geodesic Motion, And Flyby Anomaly In Fourth-Order Conformal Gravity, Gabriele U. Varieschi
Kerr Metric, Geodesic Motion, And Flyby Anomaly In Fourth-Order Conformal Gravity, Gabriele U. Varieschi
Physics Faculty Works
In this paper we analyze the Kerr geometry in the context of Conformal Gravity, an alternative theory of gravitation, which is a direct extension of General Relativity (GR). Following previous studies in the literature, we introduce an explicit expression of the Kerr metric in Conformal Gravity, which naturally reduces to the standard GR Kerr geometry in the absence of Conformal Gravity effects. As in the standard case, we show that the Hamilton–Jacobi equation governing geodesic motion in a space-time based on this geometry is indeed separable and that a fourth constant of motion—similar to Carter’s constant—can also be introduced in …
Exploration Of Climate Influences On The Abundance Of Galls On Red Willow (Salix /Aevigata) Across Two Riparian Communities In Southern California, Victor D. Carmona-Galindo, Rachael Sears, Tauras P. Vilgalys, Emily Hand, Sara Morledge-Hampton
Exploration Of Climate Influences On The Abundance Of Galls On Red Willow (Salix /Aevigata) Across Two Riparian Communities In Southern California, Victor D. Carmona-Galindo, Rachael Sears, Tauras P. Vilgalys, Emily Hand, Sara Morledge-Hampton
Biology Faculty Works
In Southern California, the red willow (Sa/ix laevigata Bebb) hosts a variety of gall-inducing parasitic insects. However, little is known about the ecology of these parasites, particularly the characterization of their microclimate preferences. This study explores the relationship between microclimate and gall frequencies in S. laevigata in the Ballona Wetlands and Temescal Canyon, and gall count correlated with biotic and abiotic factors such as soil pH, soil moisture and willow density. Significantly more galls per leaf were found at Temescal Canyon than Ballona Wetlands. Although the number of galls per leaf correlated negatively with soil pH, soil moisture content and …
Identification And Characterization Of Functionally Critical, Conserved Motifs In The Internal Repeats And N-Terminal Domain Of Yeast Translation Initiation Factor 4b (Yeif4b), Sarah F. Mitchell
Chemistry and Biochemistry Faculty Works
EIF4B has been implicated in attachment of the 43 S preinitiation complex (PIC) to mRNAs and scanning to the start codon. We recently determined that the internal seven repeats (of ∼26 amino acids each) of Saccharomyces cerevisiae eIF4B (yeIF4B) compose the region most critically required to enhance mRNA recruitment by 43 S PICs in vitro and stimulate general translation initiation in yeast. Moreover, although the N-terminal domain (NTD) of yeIF4B contributes to these activities, the RNA recognition motif is dispensable. We have now determined that only two of the seven internal repeats are sufficient for wildtype (WT) yeIF4B function in …
Principles And Properties Of Eukaryotic Mrnps, Sarah F. Mitchell
Principles And Properties Of Eukaryotic Mrnps, Sarah F. Mitchell
Chemistry and Biochemistry Faculty Works
The proper processing, export, localization, translation, and degradation of mRNAs are necessary for regulation of gene expression. These processes are controlled by mRNA-specific regulatory proteins, noncoding RNAs, and core machineries common to most mRNAs. These factors bind the mRNA in large complexes known as messenger ribonucleoprotein particles (mRNPs). Herein, we review the components of mRNPs, how they assemble and rearrange, and how mRNP composition differentially affects mRNA biogenesis, function, and degradation. We also describe how properties of the mRNP "interactome" lead to emergent principles affecting the control of gene expression.
La Formazione Degli Insegnanti: Una Necessità Non Più Rinviabile, Anna E. Bargagliotti
La Formazione Degli Insegnanti: Una Necessità Non Più Rinviabile, Anna E. Bargagliotti
Mathematics Faculty Works
No abstract provided.
Structure And Dynamics Of The Hiv-1 Frameshift Element Rna, Kathryn Mouzakis
Structure And Dynamics Of The Hiv-1 Frameshift Element Rna, Kathryn Mouzakis
Chemistry and Biochemistry Faculty Works
The HIV-1 ribosomal frameshift element is highly structured, regulates translation of all virally encoded enzymes, and is a promising therapeutic target. The prior model for this motif contains two helices separated by a three-nucleotide bulge. Modifications to this model were suggested by SHAPE chemical probing of an entire HIV-1 RNA genome. Novel features of the SHAPE-directed model include alternate helical conformations and a larger, more complex structure. These structural elements also support the presence of a secondary frameshift site within the frameshift domain. Here, we use oligonucleotide-directed structure perturbation, probing in the presence of formamide, and in-virion experiments to examine …
Simulation Of The Sampling Distribution Of The Mean Can Mislead, Ann E. Watkins, Anna E. Bargagliotti, Christine Franklin
Simulation Of The Sampling Distribution Of The Mean Can Mislead, Ann E. Watkins, Anna E. Bargagliotti, Christine Franklin
Mathematics Faculty Works
Although the use of simulation to teach the sampling distribution of the mean is meant to provide students with sound conceptual understanding, it may lead them astray. We discuss a misunderstanding that can be introduced or reinforced when students who intuitively understand that “bigger samples are better” conduct a simulation to explore the effect of sample size on the properties of the sampling distribution of the mean. From observing the patterns in a typical series of simulated sampling distributions constructed with increasing sample sizes, students reasonably—but incorrectly—conclude that, as the sample size, n, increases, the mean of the (exact) sampling …
Complete Bipartite Graphs Whose Topological Symmetry Groups Are Polyhedral, Blake Mellor
Complete Bipartite Graphs Whose Topological Symmetry Groups Are Polyhedral, Blake Mellor
Mathematics Faculty Works
We determine for which n, the complete bipartite graph Kn,n has an embedding in S3 whose topological symmetry group is isomorphic to one of the polyhedral groups: A4, A5, or S4.
Robust Noise Attenuation Under Stochastic Noises And Worst-Case Unmodelled Dynamics, Araz Hashemi, Ben G. Fitzpatrick, Le Yi Wang, George Yin
Robust Noise Attenuation Under Stochastic Noises And Worst-Case Unmodelled Dynamics, Araz Hashemi, Ben G. Fitzpatrick, Le Yi Wang, George Yin
Mathematics Faculty Works
This paper investigates noise attenuation problems for systems with unmodelled dynamics and unknown noise characteristics. A unique methodology is introduced that employs signal estimation in one phase, followed by control design for noise rejection. The methodology enjoys certain advantages in its simple control design process, accommodation of unmodelled dynamics, and non-conservative noise rejection performance. Under mild information on unmodelled dynamics, we first derive robust performance bounds on noise attenuation with respect to unmodelled dynamics without noise estimation errors. Then more general results are presented for systems that are subject to both stochastic signal estimation errors and unmodelled dynamics. Examples are …
Symmetries Of Embedded Complete Bipartite Graphs, Erica Flapan, Nicole Lehle, Blake Mellor, Matt Pittluck, Xan Vongsathorn
Symmetries Of Embedded Complete Bipartite Graphs, Erica Flapan, Nicole Lehle, Blake Mellor, Matt Pittluck, Xan Vongsathorn
Mathematics Faculty Works
We characterize which automorphisms of an arbitrary complete bipartite graph Kn,m can be induced by a homeomorphism of some embedding of the graph in S3.
Crossed Modules Of Racks, Alissa S. Crans, Friedrich Wagemann
Crossed Modules Of Racks, Alissa S. Crans, Friedrich Wagemann
Mathematics Faculty Works
We generalize the notion of a crossed module of groups to that of a crossed module of racks. We investigate the relation to categorified racks, namely strict 2-racks, and trunk-like objects in the category of racks, generalizing the relation between crossed modules of groups and strict 2-groups. Then we explore topological applications. We show that by applying the rack-space functor, a crossed module of racks gives rise to a covering. Our main result shows how the fundamental racks associated to links upstairs and downstairs in a covering fit together to form a crossed module of racks.
Hom Quandles, Alissa S. Crans, Sam Nelson
Hom Quandles, Alissa S. Crans, Sam Nelson
Mathematics Faculty Works
If A is an abelian quandle and Q is a quandle, the hom set Hom(Q,A) of quandle homomorphisms from Q to A has a natural quandle structure. We exploit this fact to enhance the quandle counting invariant, providing an example of links with the same counting invariant values but distinguished by the hom quandle structure. We generalize the result to the case of biquandles, collect observations and results about abelian quandles and the hom quandle, and show that the category of abelian quandles is symmetric monoidal closed.
An Incremental Reseeding Strategy For Clustering, Xavier Bresson, Huiyi Hu, Thomas Laurent, Arthur Szlam, James Von Brecht
An Incremental Reseeding Strategy For Clustering, Xavier Bresson, Huiyi Hu, Thomas Laurent, Arthur Szlam, James Von Brecht
Mathematics Faculty Works
In this work we propose a simple and easily parallelizable algorithm for multiway graph partitioning. The algorithm alternates between three basic components: diffusing seed vertices over the graph, thresholding the diffused seeds, and then randomly reseeding the thresholded clusters. We demonstrate experimentally that the proper combination of these ingredients leads to an algorithm that achieves state-of-the-art performance in terms of cluster purity on standard benchmarks datasets. Moreover, the algorithm runs an order of magnitude faster than the other algorithms that achieve comparable results in terms of accuracy. We also describe a coarsen, cluster and refine approach similar to GRACLUS and …