Dynamical System Approach to Cosmological Models with a Varying Speed of Light

Methods of dynamical systems have been used to study homogeneous and isotropic cosmological models with a varying speed of light (VSL). We propose two methods of reduction of dynamics to the form of planar Hamiltonian dynamical systems for models with a time dependent equation of state. The solutions are analyzed on two-dimensional phase space in the variables $(x, \dot{x})$ where $x$ is a function of a scale factor $a$. Then we show how the horizon problem may be solved on some evolutional paths. It is shown that the models with negative curvature overcome the horizon and flatness problems. The presented method of reduction can be adopted to the analysis of dynamics of the universe with the general form of the equation of state $p=\gamma(a)\epsilon$. This is demonstrated using as an example the dynamics of VSL models filled with a non-interacting fluid. We demonstrate a new type of evolution near the initial singularity caused by a varying speed of light. The singularity-free oscillating universes are also admitted for positive cosmological constant. We consider a quantum VSL FRW closed model with radiation and show that the highest tunnelling rate occurs for a constant velocity of light if $c(a) \propto a^n$ and $-1 < n \le 0$. It is also proved that the considered class of models is structurally unstable for the case of $n < 0$.Comment: 18 pages, 5 figures, RevTeX4; final version to appear in PR

Techniques for Recording Time Intervals upon Paper Ribbon

The recording of time intervals of one-hundredth second duration upon paper ribbon is possible by the use of a comparatively inexpensive set-up

Stock assessment of Queensland east coast common coral trout (Plectropomus leopardus), Australia, with data to December 2021

Queensland’s common coral trout (Plectropomus leopardus), a species of grouper, is a line-caught fish forming a single population (stock) across the Great Barrier Reef. The stock extends north from the Great Barrier Reef into the eastern Torres Strait where it is under Australian jurisdiction. There is evidence to suggest that common coral trout stay on the same individual reefs after settlement as larvae, and their larvae do not travel long distances after spawning, so the Torres Strait component of the harvest is not considered in the assessment. Common coral trout are protogynous hermaphrodites (born female, many later changing sex to male) and aggregate to spawn during spring and summer. They can grow to more than 5 kg and live for more than 18 years. This assessment builds on previous assessments that estimated the stock was at 60%, 68% and 59% of unfished biomass in 2012, 2019 and 2020 respectively. This stock assessment includes updates to the input data but keeps the methodology in line with the 2020 assessment. This stock assessment was conducted on calendar years and included input data through to December 2021. This assessment used a single-sex, age-structured population model, fit to age and length data, constructed within the Stock Synthesis modelling framework. The model was spatially structured with two subpopulations: a “blue region” subpopulation, associated with reefs in the Great Barrier Reef that remained open to fishing after the introduction of the Representative Areas Program in 2004; and a “green region” subpopulation, associated with reefs that have been closed to fishing since the introduction of the Representative Areas Program. Five scenarios were run, covering a range of modelling assumptions. Base case (most plausible) results suggested that biomass declined between 1953 and 2011 to 46% unfished biomass. At the beginning of 2022, the stock level was estimated to be 60% (50–70% range across the 95% confidence interval) of unfished spawning biomass

Reduced differential transform method for solving (1 + n) – Dimensional Burgers' equation

AbstractThis paper discusses a recently developed semi-analytic technique so called the reduced differential transform method (RDTM) for solving the (1 + n) – dimensional Burgers' equation. The method considers the use of the appropriate initial or boundary conditions and finds the solution without any discretization, transformation, or restrictive assumptions. Four numerical examples are provided in order to validate the efficiency and reliability of the method and furthermore to compare its computational effectiveness with other analytical methods available in the literature

A role for Q/N-rich aggregation-prone regions in P-body localization

P-bodies are cytoplasmic foci that are sites of mRNA degradation and translational repression. It is not known what causes the accumulation of RNA degradation factors in P-bodies, although RNA is required. The yeast Lsm1-7p complex is recruited to P-bodies under certain stress conditions. It is required for efficient decapping and degradation of mRNAs, but not for the assembly of P-bodies. Here we show that the Lsm4p subunit and its asparagine-rich carboxy-terminus are prone to aggregation and that this tendency to aggregate promotes efficient accumulation of Lsm1-7p in P-bodies. The presence of Q/N-rich regions in other P-body components suggests a more general role for aggregation-prone residues in P-body localization and assembly. This is supported by reduced P-body accumulation of Ccr4p, Pop2p and Dhh1p after deletion of these domains, and by the observed aggregation of the Q/N-rich region from Ccr4p

New Travelling Wave Solutions of Two Nonlinear Physical Models by Using a Modified Tanh-Coth Method

In this work, a modified tanh – coth method is used to derive travelling wave solutions for (2 + 1)-dimensional Zakharov-Kuznetsov (ZK) equation and (3 + 1)-dimensional Burgers equation. A new variable is used to solve these equations and established new travelling wave solutions. </jats:p

Laat de ‘echte man’ opstaan : een systematisch-theologisch onderzoek naar de rol en betekenis van masculiniteit binnen de 4e Musketier en het jeugdwerk van de Protestantse Kerk

Masterthesis Gemeentepredikant, Systematische theologi

Variable-Speed-of-Light Cosmology from Brane World Scenario

We argue that the four-dimensional universe on the TeV brane of the Randall-Sundrum scenario takes the bimetric structure of Clayton and Moffat, with gravitons traveling faster than photons instead, while the radion varies with time. We show that such brane world bimetric model can thereby solve the flatness and the cosmological constant problems, provided the speed of a graviton decreases to the present day value rapidly enough. The resolution of other cosmological problems such as the horizon problem and the monopole problem requires supplementation by inflation, which may be achieved by the radion field provided the radion potential satisfies the slow-roll approximation.Comment: 18 pages, LaTeX, revised version to appear in Phys. Rev.

On operad structures of moduli spaces and string theory

Recent algebraic structures of string theory, including homotopy Lie algebras, gravity algebras and Batalin-Vilkovisky algebras, are deduced from the topology of the moduli spaces of punctured Riemann spheres. The principal reason for these structures to appear is as simple as the following. A conformal field theory is an algebra over the operad of punctured Riemann surfaces, this operad gives rise to certain standard operads governing the three kinds of algebras, and that yields the structures of such algebras on the (physical) state space naturally.Comment: 33 pages (An elaboration of minimal area metrics and new references are added