1,816 research outputs found
hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System
We present the public version of hi_class (www.hiclass-code.net), an
extension of the Boltzmann code CLASS to a broad ensemble of modifications to
general relativity. In particular, hi_class can calculate predictions for
models based on Horndeski's theory, which is the most general scalar-tensor
theory described by second-order equations of motion and encompasses any
perfect-fluid dark energy, quintessence, Brans-Dicke, and covariant
Galileon models. hi_class has been thoroughly tested and can be readily used to
understand the impact of alternative theories of gravity on linear structure
formation as well as for cosmological parameter extraction.Comment: 17 pages + appendices, 4 figures, code available on
https://github.com/miguelzuma/hi_class_publi
Using a Fermionic Ensemble of Systems to Determine Excited States
We discuss a new numerical method for the determination of excited states of
a quantum system using a generalization of the Feynman-Kac formula. The method
relies on introducing an ensemble of non-interacting identical systems with a
fermionic statistics imposed on the systems as a whole, and on determining the
ground state of this fermionic ensemble by taking the large time limit of the
Euclidean kernel. Due to the exclusion principle, the ground state of an
-system ensemble is realized by the set of individual systems occupying
successively the lowest states, all of which can therefore be sampled in
this way. To demonstrate how the method works, we consider a one-dimensional
oscillator and a chain of harmonically coupled particles.Comment: 14 pages, Latex + 4 eps figure
Modal Uncoupling of Damped Gyroscopic Systems
A new approach for uncoupling the equations of motion typical for rotordynamical systems is presented. The method does not neglect the speed-dependent e!ects, such as gyroscopic e!ects, and can be particularly valuable in the controller design of actively controlled rotors. In the presence of hysteretic type of damping, the resulting uncoupled gyroscopic systems come with an equivalent viscous damping, equivalent in a sense of yielding the same natural frequency and decay rate. The approach is illustrated through three examples of technical interest: a Je!cott rotor with hysteretic damping, a Stodola}Green rotor, and a rotor of a small gas turbine. The generated results demonstrate that the developed approach is correct and straightforward
Modal Uncoupling of Damped Gyroscopic Systems
A new approach for uncoupling the equations of motion typical for rotordynamical systems is presented. The method does not neglect the speed-dependent e!ects, such as gyroscopic e!ects, and can be particularly valuable in the controller design of actively controlled rotors. In the presence of hysteretic type of damping, the resulting uncoupled gyroscopic systems come with an equivalent viscous damping, equivalent in a sense of yielding the same natural frequency and decay rate. The approach is illustrated through three examples of technical interest: a Je!cott rotor with hysteretic damping, a Stodola}Green rotor, and a rotor of a small gas turbine. The generated results demonstrate that the developed approach is correct and straightforward
How many invariant polynomials are needed to decide local unitary equivalence of qubit states?
Given L-qubit states with the fixed spectra of reduced one-qubit density
matrices, we find a formula for the minimal number of invariant polynomials
needed for solving local unitary (LU) equivalence problem, that is, problem of
deciding if two states can be connected by local unitary operations.
Interestingly, this number is not the same for every collection of the spectra.
Some spectra require less polynomials to solve LU equivalence problem than
others. The result is obtained using geometric methods, i.e. by calculating the
dimensions of reduced spaces, stemming from the symplectic reduction procedure.Comment: 22 page
Functional and Genetic Analysis of Coronavirus Replicase-Transcriptase Proteins
The coronavirus replicase-transcriptase complex is an assembly of viral and cellular proteins that mediate the synthesis of genome and subgenome-sized mRNAs in the virus-infected cell. Here, we report a genetic and functional analysis of 19 temperature-sensitive (ts) mutants of Murine hepatitis virus MHV-A59 that are unable to synthesize viral RNA when the infection is initiated and maintained at the non-permissive temperature. Both classical and biochemical complementation analysis leads us to predict that the majority of MHV-A59 ORF1a replicase gene products (non-structural proteins nsp1–nsp11) form a single complementation group (cistron1) while the replicase gene products encoded in ORF1b (non-structural proteins nsp12–nsp16) are able to function in trans and comprise at least three, and possibly five, further complementation groups (cistrons II–VI). Also, we have identified mutations in the non-structural proteins nsp 4, nsp5, nsp10, nsp12, nsp14, and nsp16 that are responsible for the ts phenotype of eight MHV-A59 mutants, which allows us to conclude that these proteins are essential for the assembly of a functional replicase-transcriptase complex. Finally, our analysis of viral RNA synthesis in ts mutant virus-infected cells allows us to discriminate three phenotypes with regard to the inability of specific mutants to synthesize viral RNA at the non-permissive temperature. Mutant LA ts6 appeared to be defective in continuing negative-strand synthesis, mutant Alb ts16 appeared to form negative strands but these were not utilized for positive-strand RNA synthesis, and mutant Alb ts22 was defective in the elongation of both positive- and negative-strand RNA. On the basis of these results, we propose a model that describes a pathway for viral RNA synthesis in MHV-A59-infected cells. Further biochemical analysis of these mutants should allow us to identify intermediates in this pathway and elucidate the precise function(s) of the viral replicase proteins involved
Luminosity Dependent Evolution of Lyman Break Galaxies from redshift 5 to 3
In this contribution we briefly describe our recent results on the properties
of Lyman break galaxies at z~5 obtained from deep and wide blank field surveys
using Subaru telescope, and through the comparison with samples at lower
redshift ranges we discuss the evolution of star-forming galaxies in the early
universe.Comment: 2 pages, 1 figure, for the proceedings of the IAU Symposium 235,
Galaxies Across the Hubble Time, J. Palous & F. Combes, ed
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