Universal features of correlated bursty behaviour

Inhomogeneous temporal processes, like those appearing in human communications, neuron spike trains, and seismic signals, consist of high-activity bursty intervals alternating with long low-activity periods. In recent studies such bursty behavior has been characterized by a fat-tailed inter-event time distribution, while temporal correlations were measured by the autocorrelation function. However, these characteristic functions are not capable to fully characterize temporally correlated heterogenous behavior. Here we show that the distribution of the number of events in a bursty period serves as a good indicator of the dependencies, leading to the universal observation of power-law distribution in a broad class of phenomena. We find that the correlations in these quite different systems can be commonly interpreted by memory effects and described by a simple phenomenological model, which displays temporal behavior qualitatively similar to that in real systems

Australia's insurance crisis and the inequitable treatment of self-employed midwives

Based upon a review of articles published in Australia's major newspapers over the period January 2001 to December 2005, a case study approach has been used to investigate why, when compared with other small business operators, including medical specialists, Australian governments have appeared reluctant to protect the economic viability of the businesses of self-employed midwives. Theories of agenda setting and structuralism have been used to explore that inequity. What has emerged is a picture of the complex of factors that may have operated, and may be continuing to operate, to shape the policy agenda and thus prevent solutions to the insurance problems of self-employed midwives being found

Dynamism in the solar core

Recent results of a mixed shell model heated asymmetrically by transient increases in nuclear burning indicate the transient generation of small hot spots inside the Sun somewhere between 0.1 and 0.2 solar radii. These hot bubbles are followed by a nonlinear differential equation system with finite amplitude non-homologous perturbations which is solved in a solar model. Our results show the possibility of a direct connection between the dynamic phenomena of the solar core and the atmospheric activity. Namely, an initial heating about DQ_0 ~ 10^{31}-10^{37} ergs can be enough for a bubble to reach the outer convective zone. Our calculations show that a hot bubble can arrive into subphotospheric regions with DQ_final ~ 10^{28} - 10^{34} ergs with a high speed, up to 10 km s-1, approaching the local sound speed. We point out that the developing sonic boom transforms the shock front into accelerated particle beam injected upwards into the top of loop carried out by the hot bubble above its forefront traveling from the solar interior. As a result, a new perspective arises to explain flare energetics. We show that the particle beams generated by energetic deep-origin hot bubbles in the subphotospheric layers have masses, energies, and chemical compositions in the observed range of solar chromospheric and coronal flares. It is shown how the emergence of a hot bubble into subphotospheric regions offers a natural mechanism that can generate both the eruption leading to the flare and the observed coronal magnetic topology for reconnection. We show a list of long-standing problems of solar physics that our model explains. We present some predictions for observations, some of which are planned to be realized in the near future.Comment: 44 pages, 20 figure

The ASKAP Variables and Slow Transients (VAST) Pilot Survey

The Variables and Slow Transients Survey (VAST) on the Australian Square Kilometre Array Pathfinder (ASKAP) is designed to detect highly variable and transient radio sources on timescales from 5 s to ~5 yr. In this paper, we present the survey description, observation strategy and initial results from the VAST Phase I Pilot Survey. This pilot survey consists of ~162 h of observations conducted at a central frequency of 888 MHz between 2019 August and 2020 August, with a typical rms sensitivity of 0.24 mJy beam-1 and angular resolution of 12 -20 arcseconds. There are 113 fields, each of which was observed for 12 min integration time, with between 5 and 13 repeats, with cadences between 1 day and 8 months. The total area of the pilot survey footprint is 5 131 square degrees, covering six distinct regions of the sky. An initial search of two of these regions, totalling 1 646 square degrees, revealed 28 highly variable and/or transient sources. Seven of these are known pulsars, including the millisecond pulsar J2039-5617. Another seven are stars, four of which have no previously reported radio detection (SCR J0533-4257, LEHPM 2-783, UCAC3 89-412162 and 2MASS J22414436-6119311). Of the remaining 14 sources, two are active galactic nuclei, six are associated with galaxies and the other six have nomulti-wavelength counterparts and are yet to be identified