Error enhancement in geomagnetic models derived from scalar data

Models of the main geomagnetic field are generally represented by a scalar potential gamma expanded in a finite number of spherical harmonics. Very accurate observations of F were used, but indications exist that the accuracy of models derived from them is considerably lower. One problem is that F does not always characterize gamma uniquely. It is not clear whether such ambiguity can be encountered in deriving gamma from F in geomagnetic surveys, but there exists a connection, due to the fact that the counterexamples of Backus are related to the dipole field, while the geomagnetic field is dominated by its dipole component. If the models are recovered with a finite error (i.e. they cannot completely fit the data and consequently have a small spurious component), this connection allows the error in certain sequences of harmonic terms in gamma to be enhanced without unduly large effects on the fit of F to the model

Photonuclear interactions of ultrahigh energy cosmic rays and their astrophysical consequences

Results of detailed Monte Carlo calculations of the interaction histories of ultrahigh energy cosmic-ray nuclei with intergalactic radiation fields are presented. Estimates of these fields and empirical determinations of photonuclear cross sections are used, including multinuclear disintegrations for nuclei up to 56Fe. Intergalactic and galactic energy loss rates and nucleon loss rates for nuclei up to 56Fe are also given. Astrophysical implications are discussed in terms of expected features in the cosmic-ray spectrum between quintillion and sextillion eV for the universal and supercluster origin hypotheses. The results of these calculations indicate that ultrahigh energy cosmic rays cannot be universal in origin regardless of whether they are protons or nuclei. Both the supercluster and galactic origin hypotheses, however, are possible regardless of nuclear composition

Fluorescence and phosphorescence of photomultiplier window materials under electron irradiation

The fluorescence and phosphorescence of photomultiplier window materials under electron irradiation were investigated using a Sr-90/Y-90 beta emitter as the electron source. Spectral emission curves of UV grade, optical grade, and electron-irradiated samples of MGF2 and LiF, CaF2, BaF2, sapphire, fused silica, and UV transmitting glasses were obtained over the spectral range of 200 nm to 650 nm. Fluorescence yields, expressed as the number of counts in a solid angle of 2 pi steradian per 1MeV of incident electron energy deposited, were determined on these materials utilizing photomultiplier tubes with cesium telluride, bialkali, and trialkali (S-20) photocathodes, respectively

Cosmic antimatter annihilation and the gamma-ray background spectrum

Cosmic antimatter annihilation and gamma ray background spectru

The professional knowledge that counts in Australian contemporary early childhood teacher education

Australia is typical of many western countries where the provision of quality early childhood services has become a government priority. The government initiatives in Australia include repeated demands for 'well-qualified' early childhood educators. As a result of these demands the preservice preparation of early childhood educators is under intense scrutiny. This scrutiny raises many questions regarding the knowledge base considered to be essential for early childhood educators and leads to further questions about who has the authority to produce this knowledge. This article explores these questions by firstly examining some of the ways Australian early childhood teacher education is situated within the current knowledge environment. This is followed by a discussion regarding the debates about what early childhood educators 'need to know'. The third section of the article traces some of the historical features of Australian early childhood teacher education, for the author argues that contemporary questions about 'which' knowledge is to be included in early childhood teacher education are best understood alongside their historical precedents. The article concludes by considering the implications of the debates for contemporary early childhood teacher education and suggests that a way forward involves reconsidering the traditional binary between theory and practical knowledge

Wastage amidst shortage: Strategies for the mitigation of standby electricity in residential sector in Nigeria

Abstract : Due to rising population and the increasing rate of urbanization, residential electricity usage accounts for a large chunk of Nigeria’s electricity consumption. However, little attention is paid to electricity conservation in the country. In response to this, several studies are been tailored to ensure a rapid reduction in energy consumption through various alternatives including energy efficient technologies given the current state of inadequate electricity supply in the country. On this note, this article discusses the significance of standby electricity in Nigeria. The electricity generation and consumption patterns were briefly discussed while the current electricity saving behaviour and practices among the urban dwellers were detailed with a case study analysed. Based on the case study, it was discovered that the mean standby load across the 30 households were estimated at 60 W ranging from 34-144 W. Also, standby consumption accounts for 13-44% of the annual electricity consumption across the households. Finally, the strategies for electricity saving and sustainable consumption, most especially the mitigation of standby electricity were highlighted

Head of State of Exception

During the escalation of the “German Autumn” in 1977 the Federal German government resorted to a specific form of crisis management that had been described as an undeclared state of exception. It was Federal chancellor Helmut Schmidt in the first place who oversaw the anti-terrorist measures in the situation room where the executive branch ruled for six weeks beyond any parliamentary control. This article examines the role that Helmut Schmidt had played for the creation of a “subjective state of exception” (Julius Hatschek) and how this could be seen as stemming from Schmidt’s earlier experiences and handling of crisis situations dating back to the 1960s. In this regard it has to be asked with Giorgio Agamben, if in the West German case, the state of exception had become the rule

Neurointerfaces, mental imagery and sensory translation in art and science in the digital age

The chapter focuses on the issue of transmedial and sensory exchange in the context of digital culture and biometric technology. It analyzes critically the epistemic claims behind the various brain-scanning technologies, focusing on the status of the inner images that underlie cognitive activity. Multimedia performances and artistic experiments designed in collaboration with neuroscientists open up new dimensions in the discussion of translation between different sensory modalities, as well as translation between human perceptive apparatus and computational systems. Engaging the methodologies of contemporary image science and critical neuroscience, the paper shows how artistic scenarios help to both localize and expand our understanding of mental imagery and to offer an alternative to the existing correlations-based approach.FGW – Publications without University Leiden contrac

Effect of artemether-lumefantrine policy and improved vector control on malaria burden in KwaZulu-Natal, South Africa

Between 1995 and 2000, KwaZulu–Natal province, South Africa, experienced a marked increase in Plasmodium falciparum malaria, fuelled by pyrethroid and sulfadoxine-pyrimethamine resistance. In response, vector control was strengthened and artemether-lumefantrine (AL) was deployed in the first Ministry of Health artemisinin-based combination treatment policy in Africa. In South Africa, effective vector and parasite control had historically ensured low-intensity malaria transmission. Malaria is diagnosed definitively and treatment is provided free of charge in reasonably accessible public-sector health-care facilities