On the Weyl Curvature Hypothesis

The Weyl curvature hypothesis of Penrose attempts to explain the high homogeneity and isotropy, and the very low entropy of the early universe, by conjecturing the vanishing of the Weyl tensor at the Big-Bang singularity. In previous papers it has been proposed an equivalent form of Einstein's equation, which extends it and remains valid at an important class of singularities (including in particular the Schwarzschild, FLRW, and isotropic singularities). Here it is shown that if the Big-Bang singularity is from this class, it also satisfies the Weyl curvature hypothesis. As an application, we study a very general example of cosmological models, which generalizes the FLRW model by dropping the isotropy and homogeneity constraints. This model also generalizes isotropic singularities, and a class of singularities occurring in Bianchi cosmologies. We show that the Big-Bang singularity of this model is of the type under consideration, and satisfies therefore the Weyl curvature hypothesis.Comment: 10 pages, slides at http://www.sciencedirect.com/science/article/pii/S000349161300171

Spin-Isospin Excitations and Muon Capture by Nuclei

By analyzing the energy-weighted moments of the strength function calculated in RPA and beyond it is shown that the explanation of the effect of missing strength of Gamow-Teller transitions requires that residual interaction produce high-excited $1^{+}$ particle-hole collective states. The example of this interaction is presented. The manifestations of spin-isospin nuclear response in nuclear muon capture are discussed.Comment: 16 pages, 5 figures, 2 tables. The talk at the XVI International School on Nuclear Physics, Neutron Physics and Nuclear Energy, September 19-26, Varna, Bulgari

Emergent Quantum Mechanics and Emergent Symmetries

Quantum mechanics is 'emergent' if a statistical treatment of large scale phenomena in a locally deterministic theory requires the use of quantum operators. These quantum operators may allow for symmetry transformations that are not present in the underlying deterministic system. Such theories allow for a natural explanation of the existence of gauge equivalence classes (gauge orbits), including the equivalence classes generated by general coordinate transformations. Thus, local gauge symmetries and general coordinate invariance could be emergent symmetries, and this might lead to new alleys towards understanding the flatness problem of the Universe.Comment: 10 pages, 1 figure. Presented at PASCOS 13, Imperial College, London, July 6, 200

Neutrino-less Double Electron Capture - a tool to research for Majorana neutrinos

The possibility to observe the neutrino-less double $\beta$ decay and thus to prove the Majorana nature of neutrino as well as provide a sensitive measure of its mass is a major challenge of to-day's neutrino physics. As an attractive alternative we propose to study the inverse process, the radiative neutrino-less double electron capture $0 \nu 2EC$. The associated monoenergetic photon provides a convenient experimental signature. Other advantages include the favourable ratio of the $0 \nu 2EC$ to the competing $2\nu 2EC$ capture rates and, very importantly, the existence of coincidence trigger to suppress the random background. These advantages partly offset the expected longer lifetimes. Rates for the $0\gamma 2EC$ process are calculated. High Z atoms are strongly favoured. A resonance enhancement of the capture rates is predicted at energy release comparable to the $2P-1S$ atomic level difference. The resonance conditions are likely to be met for decays to excited states in final nuclei. Candidates for such studies are considered. The experimental feasibility is estimated and found highly encouraging.Comment: New figure added, table updated, physical background discusse

The influence of Mg doping on the nucleation of self-induced GaN nanowires

GaN nanowires were grown without any catalyst by plasma-assisted molecular beam epitaxy. Under supply of Mg, nanowire nucleation is faster, the areal density of wires increases to a higher value, and nanowire coalescence is more pronounced than without Mg. During nanowire nucleation the Ga desorption was monitored insitu by line-of-sight quadrupolemass spectrometry for various substrate temperatures. Nucleation energies of 4.0±0.3 eV and 3.2±0.3 eV without and with Mg supply were deduced, respectively. This effect has to be taken into account for the fabrication of nanowire devices and could be employed to tune the NW areal density

Could Religiosity and Religion Influence the Tax Morale of Individuals? An Empirical Analysis Based on Variable Selection Methods

When people who adhere to tax morality act in a situation where there is no sense of risk, no acceptance of the government, or no environment conducive to tax compliance, it is easier to see how they are motivated to do so. Tax morality is also known as the ethics of compliance. It is the independent cause that motivates a positive tax behaviour. Employees' religious beliefs may impact their ideas and actions in organizational life, just as individuals' attitudes, values, emotions, abilities, and behaviours influence their thoughts and actions at work. Religion can positively influence a worker's loyalty, morale, and communication. In this context, the research seeks to determine whether religiosity and religion may have an effect on tax morale, examining whether an individual’s religiosity reduces tax evasion and increases the degree of tax morale. Using machine learning variable selection techniques appropriate for categorical variables, we have used the dataset of the Joint EVS/WVS 2017-2020 (European Value Survey/World Value Survey), allowing for comparisons of tax morality in more than 79 nations globally (chi-squared and mutual information). The empirical findings showed that the most important aspects of religiosity, such as religious denomination, belief in God, and the significance of God, along with the degree of trust placed in other religions and churches, have a considerable positive impact on the level of tax morale. Another significant conclusion relates to how much people feel the government is responsible, how much they care about their nation, and how satisfied they are with the political system - findings that have been shown to boost employee morale. The following are a person's primary traits that indicate their financial morale: an adult above the age of 25, a full-time worker or retired person, married, and living alone. Therefore, employees that are morally upright, trustworthy, diligent, and committed to the workplace values of justice and decency raise morale generally and improve an organisation's success. A business may enhance its reputation and help to secure its long-term success by establishing behavioural policies

Fully-Renormalized QRPA fulfills Ikeda sum rule exactly

The renormalized quasiparticle-RPA is reformulated for even-even nuclei using restrictions imposed by the commutativity of the phonon creation operator with the total particle number operator. This new version, Fully-Renormalized QRPA (FR-QRPA), is free from the spurious low-energy solutions. Analytical proof is given that the Ikeda sum rule is fullfiled within the FR-QRPA.Comment: 9 page