Application of Artificial Neural Networks in Climatology: A Case Study of Sunspot Prediction and Solar Climate Trends

Global temperature trends on time scales of years to centuries have recently been shown to be related to volcanic aerosols, carbon dioxide levels, and solar activity. The most visible and well-studied indicators of solar variability are dark areas or “sunspots” on the surface of the Sun, with sunspot numbers directly related to the level of solar activity. Prediction of sunspot numbers in advance of the actual event has proven problematic with most methods failing due to nonlinearities in solar activity. An approach using the generation of a feedforward neural network may resolve some of the difficulties inherent in currently utilized statistical and precursor approaches since feedforward networks offer a useful and practical method of approximating nonlinear relations and their derivatives without knowing the actual underlying nonlinear function. In this paper, we show some preliminary findings in using feedforward neural networks for the prediction of peak sunspot cycle amplitude and discuss the climatic implications of the findings.     

An assessment of morphological criteria for discriminating sheep and goat mandibles on a large prehistoric archaeological assemblage (Kerma,Sudan)

This paper presents an assessment of all known dental and mandibular morphological criteria for differentiating sheep (Ovis aries) and goats (Capra hircus) using for the first time an archaeological sample of complete caprine skeletons (90 sheep and 13 goats) from burials at Kerma (Sudan, 3rd and 2nd millennia BC). The species determinations were assessed using cranial and post-cranial morphological criteria. Consequently, the reliability (percentage of correct determination) and efficiency (complementary percentage of intermediate scores i.e. neither sheep nor goat) of 38 individual dental criteria could be fully assessed using a prehistoric homogeneous domesticate population. We demonstrate that, for this sample, individual criteria for lacteal teeth are more reliable for sheep (sheep: 95 ± 3%) than the adult premolars (85 ± 5%) and molars (sheep: 88 ± 2%), whereas for goats premolar criteria were more reliable (83 ± 12%). For efficiency, lacteal dental criteria are better (goat: 97 ± 5%; sheep: 95 ± 3%) than those for premolar (goat: 85 ± 10%; sheep: 79 ± 5%) and molar (goat: 82 ± 6%; sheep: 83 ± 2). We also demonstrated that most isolated teeth can be determined with less than 10% error. However, on average, within specific age classes (0–1 year, 1–4 years and more than 4 years), isolated teeth increased in reliability and decreased in efficiency. The average reliability of the criteria for complete mandibles for each age class for goats and sheep was 100%, when the efficiency was 67, 40 and 50% for goats and over 90% for sheep. This is due to the effect of age on the efficiency of isolated criteria and the poor performance of specific criteria mainly those P3, M1 and M2. We conclude that separate species kill-off profiles are possible. The effect of age on dental criteria would not significantly change the interpretation for specific subsistence strategies focused on one particularly species.     

Sounding Presidential: Frame Creation in the Obama Administration

Among the often-cited powers of the presidency is the power of the pulpit. Presidents attempt to influence Congress directly and indirectly through their rhetoric and its influence on national policy debates. This includes the power to shape debates through the use of frames. While much is known about framing, no past study has attempted to document all frames utilized by a policy entrepreneur in his attempt to shape the policy debate. Comprehensive understanding of frame creation is necessary to understand what frames persist and how frames are used in policymaking. This study identifies how one president, Barack Obama, framed domestic policy issues in speeches early in his administration. Identifying frames the president uses provides insights into this president's attempts to set the public agenda. The findings of this study suggest that Obama's use of specific frames is highly idiosyncratic, but that these idiosyncratic frames coalesce around identifiable policy areas, particularly macroeconomic policy. This study provides insight into how one president attempts to both frame and set his domestic policy agenda.     

Diversification,Intensification and Specialization: Changing Land Use in Western Africa from 1800 BC to AD 1500

Journal of World Prehistory - Many societal and environmental changes occurred between the 2nd millennium BC and the middle of the 2nd millennium AD in western Africa. Key amongst these were...