Random Sequential Adsorption of Objects of Decreasing Size

We consider the model of random sequential adsorption, with depositing objects, as well as those already at the surface, decreasing in size according to a specified time dependence, from a larger initial value to a finite value in the large time limit. Numerical Monte Carlo simulations of two-dimensional deposition of disks and one-dimensional deposition of segments are reported for the density-density correlation function and gap-size distribution function, respectively. Analytical considerations supplement numerical results in the one-dimensional case. We investigate the correlation hole - the depletion of correlation functions near contact and, for the present model, their vanishing at contact - that opens up at finite times, as well as its closing and reemergence of the logarithmic divergence of correlation properties at contact in the large time limit.Comment: Submitted for publicatio

Higgs-dilaton model revisited: can dilaton act as QCD axion?

The Standard Model Lagrangian has an approximate scale symmetry in the high-energy limit. This observation can be included in the fundamental principle of the ultimate theory of Nature as the requirement of the exact quantum scale invariance. In this setup, all low-energy particle phenomenology can be obtained as a result of the spontaneous breaking of scale symmetry leading to the presence of the extra massless scalar field -- the dilaton. We explore the scenario in which this field is capable of solving the strong CP-problem in QCD in a similar way as in QCD axion models. The dilaton, playing the role of the axion, is coupled to the QCD sector and acquires a mass term due to non-perturbative breaking of scale symmetry. We show that the dilaton can form dark matter after the low-scale inflation. As a proof of concept, we construct a model of Higgs-driven inflation consistently realising the axion-like dilaton dark matter production compatible with the CMB data.Comment: 32 pages, 8 figures; additional calculations, comments and references added, several plots upgraded, typos correcte

Experiencing the progress report: an analysis of gender and administration in doctoral candidature

Most universities around the world put in place administrative processes and systems to manage student progress. These processes usually involve filling out standardised forms and instruments: managerial tools intended to increase transparency, promote efficiency and ensure fairness by applying the same standards to all. The progress report is a widely used management tool in doctoral candidature in Australia and in other countries which look to the United Kingdom for degree structure and format. This reporting mechanism requires students and supervisors to make a retrospective account of the research done in a given period. The intention of the progress report is to provide a mechanism for recording feedback and an opportunity to clarify communication between supervisors, students and the institution itself on the progress of the research. However, whether these managerial tools achieve these aims in doctoral candidature is questionable. In this paper, we report on findings from a study of progress reporting in doctoral studies in one middle-band university in Australia. We found that men and women reported qualitative differences in their encounters with the progress reporting mechanisms, which called into question the idea that these management tools are gender neutral and fair in their effects or application

Relativistic Model of Detonation Transition from Neutron to Strange Matter

We study the conversion of neutron matter into strange matter as a detonation wave. The detonation is assumed to originate from a central region in a spherically symmetric background of neutrons with a varying radial density distribution. We present self-similar solutions for the propagation of detonation in static and collapsing backgrounds of neutron matter. The solutions are obtained in the framework of general relativistic hydrodynamics, and are relevant for the possible transition of neutron into strange stars. Conditions for the formation of either bare or crusted strange stars are discussed.Comment: 16 pages, 4 figures. Submitted to IJMP

Metal Oxide Porous Coatings for Implantant Materials

The paper presents the results of survey, dedicated to synthesis of metal oxide coatings on porous materials applied for implant surgery (stainless steel 12X18H9T, titanium alloy and high-purity niobium VT5). This article examines kinetic features of electrochemical formation of anodic oxide coatings on steel, niobium and titanium. It is shown that for steel anodic treatment method does not provide a reliable surface passivation (no current decay, the surface indicates the transition to the passive state).Analysis of polarization dependences obtained on niobium and titanium in electrolytes with an activator (F-), indicates surface passivation (current slump), and at potentials above 2 on the surface of a transition curves in transpassive state (as evidenced by the current increase). Consequently, it can be concluded that presence of F- results surface activation of titanium and niobium electrode (F- oxide reacts to form water-soluble complexes) that promotes nucleation and formation of pores of the porous structure of the oxide coating.SEM results verify the presence of self-organized porous oxide film synthesized on titanium and niobium in solutions containing F-