Electric characteristics of pseudo-spark during breakdown phase

An analysis of the time-dependent resistive voltage and power deposition during the breakdown phase of pseudo-spark is presented. The voltage and current were measured by specially designed low-inductance capacitive voltage divider and current measuring resistor. The measured waveforms of voltage and current are digitized and processed by a computer program to remove the inductive component, so as to obtain resistive voltage and power deposition. The influence of pressure, cathode geometry and charging voltage of storage capacitors on the electrical properties in the breakdown phase are investigated. The results suggest that the breakdown phase of pseudo-spark consists of three stages. The first stage is mainly hollow cathode discharge. In the second stage, field-enhanced thermionic emission takes place, resulting in a fast voltage drop and sharp rise of discharge current. The third stage of discharge depends simply on the parameters of the discharge circuit.

Explorations of electric-current system in solar active regions .1. Empirical inferences of the current flows

In this paper we explore techniques to identify sources of electric current systems and their channels of flow in solar active regions. Measured photospheric vector magnetic fields (VMF) together with high-resolution white-light and H filtergrams provide the data base to derive the current systems in the photosphere and chromosphere. Simple mathematical constructions of fields and currents are also adopted to understand these data. As an example, the techniques are then applied to infer current systems in AR 2372 in early April 1980. The main results are: (i) In unipolar sunspots the current density may reach values of 103 CGSE, and the Lorentz force on it can accelerate the Evershed flow, (ii) Spots exhibiting significant spiral pattrn in the penumbral filaments are the sources of vertical major currents at the photospheric surface, (iii) Magnetic neutral lines where the transverse field was strongly sheared were channels along which strong current system flows, (iv) The inferred current systems produced oppositely-flowing currents in the area of the delta configuration that was the site of flaring in AR 2372.

"I'm on it 24/7 at the moment" : A qualitative examination of multi-screen viewing behaviours among UK 10-11 year olds

Background: Screen-viewing has been associated with increased body mass, increased risk of metabolic syndrome and lower psychological well-being among children and adolescents. There is a shortage of information about the nature of contemporary screen-viewing amongst children especially given the rapid advances in screen-viewing equipment technology and their widespread availability. Anecdotal evidence suggests that large numbers of children embrace the multi-functionality of current devices to engage in multiple forms of screen-viewing at the same time. In this paper we used qualitative methods to assess the nature and extent of multiple forms of screen-viewing in UK children. Methods: Focus groups were conducted with 10-11 year old children (n = 63) who were recruited from five primary schools in Bristol, UK. Topics included the types of screen-viewing in which the participants engaged; whether the participants ever engaged in more than one form of screen-viewing at any time and if so the nature of this multiple viewing; reasons for engaging in multi-screen-viewing; the room within the house where multi-screen-viewing took place and the reasons for selecting that room. All focus groups were transcribed verbatim, anonymised and thematically analysed. Results: Multi-screen viewing was a common behaviour. Although multi-screen viewing often involved watching TV, TV viewing was often the background behaviour with attention focussed towards a laptop, handheld device or smart-phone. There were three main reasons for engaging in multi-screen viewing: 1) tempering impatience that was associated with a programme loading; 2) multi-screen facilitated filtering out unwanted content such as advertisements; and 3) multi-screen viewing was perceived to be enjoyable. Multi-screen viewing occurred either in the child's bedroom or in the main living area of the home. There was considerable variability in the level and timing of viewing and this appeared to be a function of whether the participants attended after-school clubs. Conclusions: UK children regularly engage in two or more forms of screen-viewing at the same time. There are currently no means of assessing multi-screen viewing nor any interventions that specifically focus on reducing multi-screen viewing. To reduce children's overall screen-viewing we need to understand and then develop approaches to reduce multi-screen viewing among children.

Spatio-Temporal Scanning and Statistical Test of the Accelerating Moment Release (AMR) Model Using Australian Earthquake Data

The Accelerating Moment Release (AMR) preceding earthquakes with magnitude above 5 in Australia that occurred during the last 20 years was analyzed to test the Critical Point Hypothesis. Twelve earthquakes in the catalog were chosen based on a criterion for the number of nearby events. Results show that seven sequences with numerous events recorded leading up to the main earthquake exhibited accelerating moment release. Two occurred near in time and space to other earthquakes preceded by AM R. The remaining three sequences had very few events in the catalog so the lack of AMR detected in the analysis may be related to catalog incompleteness. Spatio-temporal scanning of AMR parameters shows that 80% of the areas in which AMR occurred experienced large events. In areas of similar background seismicity with no large events, 10 out of 12 cases exhibit no AMR, and two others are false alarms where AMR was observed but no large event followed. The relationship between AMR and Load-Unload Response Ratio (LURR) was studied. Both methods predict similar critical region sizes, however, the critical point time using AMR is slightly earlier than the time of the critical point LURR anomaly.