Measurements of the 2001 April 15 and 2005 January 20 ground -level enhancements by the Milagro water Cerenkov detector

The Sun is capable of accelerating particles up to high energies, the highest of which (\u3e1 GeV) are detectable at the Earth\u27s surface. Although the accelerating source is tied to the solar magnetic field, the physical process responsible continues to be debated. Essential information about the location and nature of the acceleration mechanism can be obtained from measurements of the highest-energy particles. The Milagro instrument was originally designed as a very-high-energy gamma-ray detector, but was also sensitive to cosmic rays and high-energy solar particles. Milagro registered ground-level enhancements for the 2001 April 15 and 2005 January 20 solar events during its operation from January 2000 to March 2008, the latter of which was the most intense in 50 years. The multiple data channels in Milagro, combined with complementary neutron monitor data, enabled for a detailed analysis of the energetic proton spectra even during the brief anisotropic phase of the 2005 January 20 event. For both events the results for the proton spectra are consistent with a coronal shock origin. A timing analysis for the controversial 2005 January 20 event reveals that the prompt arrival of the relativistic protons and rapid evolution of the observed profiles measured at ground-level stations can be attributed to a coronal shock origin and do not require an additional or different process, i.e., direct solar-flare acceleration

Of Printmaking, Creativity and Studio Practice: A Dialogue with Malcolm Christian, Caverhsam Press

Malcolm Christian is a 67-year old South African who grew up in Durban (Natal, KwaZulu-Natal). His parentage was of the second, third generations from UK. He spent his first 24 years in South Africa doing his studies before going to London for one-year scholarship: On finishing school he completed a Diploma in Fine Art majoring in sculpture combined with a certificate in photography at the Natal College for Technical Education. He won an overseas scholarship which enabled him to study printmaking at Croydon College for Art and Design, London. After returning to South Africa he taught in a number of tertiary education institutions prior to taking a life-changing decision to go into practice, establishing a printmaking press (studio) which a wide-range of artists have continued to leverage upon. His press at the ‘lonely’ midland of Caversham in KwaZulu-Natal has remained a huge facility of a studio, first of its kind in South Africa, established in 1985. Malcolm has, by his collaborative engagement at Caversham studio, grounded a creative osmosis between formal institutions of art and professional practitioners. This he does by admitting artists for residences, organising workshops for young learners. This creative initiative has also budded into brilliant strands such as the Caversham Centre for Artists and Writers, CreACTive Centres and the entrepreneurial model for hand-made fabric printing and workshop, the Caversham Textile. Malcolm’s approach is an excellent paradigm for today’s artists and professional producers of creative culture. Kathy Arbuckle of University of KwaZulu-Natal convivially referred to him as a ‘Picasso’. I sat down with him in April 2018 to dialogue in details

Development of DC Circuit Breakers for Medium-Voltage Electrified Transportation

Medium-voltage DC (MVDC) distribution is an enabling technology for the electrification of transportation such as aircraft and shipboard. One main obstacle for DC distribution is the lack of adequate circuit fault protection. The challenges are due to the rapidly rising fault currents and absence of zero crossings in DC systems compared to AC counterparts. Existing DC breaker solutions lack comprehensive consideration of energy efficiency, power density, fault interruption speed, reliability, and implementation cost. In this thesis, two circuit topologies of improved DC circuit breakers are developed: the resonant current source based hybrid DC breaker (RCS-HDCB) and the high temperature superconductor fault current limiter based solid state DC breaker (HTS-FCL-SSDCB). The RCS-HDCB utilizes a controllable resonant current source based upon wide bandgap (WBG) switches that enable low loss and fast fault interruption due to the fast switching speed. The voltage applied by the controllable resonant current source is much lower than the rated voltage of the DC breaker, allowing the utilization of significantly lower voltage rated WBG switches. The conduction path\u27s sole component is a fast-actuating ultra-low resistance vacuum interrupter for high efficiency during normal operation. As the second DC breaker concept, the HTS-FCL-SSDCB is subdivided into a fault current limiter (FCL) and solid state DC breaker (SSDCB). The FCL is based upon a high temperature superconductor cable which has natural fault current limiting capabilities while having negligible insertion losses for normal load currents. The SSDCB utilizes WBG switches to decrease conduction losses compared to Silicon-based breakers. The FCL reduces fault current such that the number of semiconductive switches in the SSDCB is minimized. Both breakers feature a metal-oxide varistor device in parallel to clamp overvoltages and dissipate energy after fault interruption. Modeling, simulation, and analysis in electrical and thermal domains are conducted to verify the functionality of the DC circuit breakers. The simulation results confirm the feasibility of these two DC breakers in their proposed applications of 2.4 kV electric aircraft and 20 kV shipboard MVDC distribution systems

Schools in Balance: Comparing Iowa Physics Teachers and Teaching in Large and Small Schools

In 2009 we surveyed all known Iowa high school physics teachers to gain insight into their educational backgrounds, instructional styles, content coverage, and available resources. Based upon a suggestion made at a subsequent presentation, we reexamined the collected data, comparing the responses of teachers from small and large schools to see if there were notable differences between the two populations. We found that teachers at larger schools teach a wider variety of physics courses, including more advanced and “physics first” style courses, and report stronger educational backgrounds in physics. While larger schools also have more financial resources allocated for physics teaching, the larger enrollments in physics courses at these schools means there is roughly the same amount of available money per student at all schools

Happiness and age in European adults: The moderating role of gross domestic product per capita.

Studies of happiness levels across the life span have found support for two rival hypotheses. The positivity effect states that as people get older, they increasingly attend to positive information, which implies that happiness remains stable or increases with age, whereas the U-shaped hypothesis posits a curvilinear shape resulting from a dip during midlife. Both have been presented as potentially universal hypotheses that relate to cognitive and/or biological causes. The current study examined the happiness-age relationship across 29 European nations (N = 46,301) to explore whether it is moderated by national wealth, as indexed by Gross Domestic Product (GDP) per capita. It was found that eudaimonic and hedonic happiness remained relatively stable across the life span only in the most affluent nations; in poorer nations, there was either a fluctuating or steady age-associated decline. These findings challenge the cultural universality of the happiness-age relationship and suggest that models of how age relates to happiness should include the socioeconomic level of analysis

Running While Standing Still: Rethinking ICT Business Model Decisions for the New Cloud Economy

Cloud computing has underpinned an accelerated business model evolution for delivering ICT solutions. However, some established business model mature ICT providers are experiencing substantial difficulties related to the formulation of effective business models. Currently, there is dearth of IS research relating to deciphering how large business model mature ICT providers can effectively formalise and sustain competitive cloud enabled business model decisions. Thus, in order to extend the extant research, we derive a conceptual framework as a reference model which is based on business model and decision making theory. We then apply our framework to an in-depth case study of an established large ICT provider (Alpha) who have been provisioning cloud services for the past five years. Our findings reveal how the case organisation are executing their core business model decisions along increasingly specific decision making levels in order to effectively sustain their competitiveness. Our analysis provides new insight into the role of using the business model as a focusing device for enabling the effective provision of cloud technology

The Impact of Cloud-Based Digital Transformation on ICT Service Providers’ Strategies

The relationship between digital transformation and strategy formulation in the context of new digital technologies is emerging as a research area which is ripe for investigation. Recently, information system researchers have focused their attention on exploring this relationship in the context of cloud computing-based digital transformation. However, while extant research has explored this relationship from an adopter perspective, there is a dearth of research which has used an information and communications technology (ICT) service provision viewpoint. Taking the perspective of fifteen ICT service providers, this comparative case study elucidates how cloud-based digital transformation has impacted these organisations’strategy formulation processes. This paper provides the following insights. First, cloud-based digital transformation can positively impact the realisation of strategic objectives in terms of deliberate strategies such as agility and competitive positioning. Second, we present a process model which delineates how ICT service providers’strategy formulation was observed to be an emergent process, encompassing recursive cycles of business model experimentation and iteration, organisational learning and organisational adaptation, primarily as a result of the profound disruptive and innovative impact of cloud-based digital transformation