Rational expectations and near rational alternatives: How best to form expectations

Learning rules are increasingly being used in macroeconomic models. However one criticism that has been levelled at this assumption is that the choice of variables for inclusion in the learning rule, and the actual specification of the learning rule itself, is arbitrary. In this paper we test how important the particular learning rule specification is by incorporating a battery of learning rules into a large-scale macro model. The model's dynamics are then compared to those from a version of the model simulated under rational expectations (RE). The results indicate that although there are large differences between the RE solution and each of the solutions under learning, differences amongst the learning rule solutions are minor JEL Classification: C53, E43, F33

The Greek financial crisis: growing imbalances and sovereign spreads

We discuss the origins of the Greek financial crisis as manifested in the growing fiscal and current-account deficits since euro-area entry in 2001. We then provide an investigation of spreads on Greek relative to German long-term government debt. Using monthly data over the period 2000 to 2010, we estimate a cointegrating relationship between spreads and their long-term fundamental determinants, and compare the spreads predicted by this estimated relationship with actual spreads. We find periods of both undershooting and overshooting of spreads compared to what is predicted by the economic fundamentals.Greek financial crisis; sovereign spreads

Rational expectations and near rational alternatives: How best to form expectations

Learning rules are increasingly being used in macroeconomic models. However one criticism that has been levelled at this assumption is that the choice of variables for inclusion in the learning rule, and the actual specification of the learning rule itself, is arbitrary. In this paper we test how important the particular learning rule specification is by incorporating a battery of learning rules into a large-scale macro model. The model's dynamics are then compared to those from a version of the model simulated under rational expectations (RE). The results indicate that although there are large differences between the RE solution and each of the solutions under learning, differences amongst the learning rule solutions are mino

A 1000-year carbon isotope rainfall proxy record from South African baobab trees (Adansonia digitata L.)

A proxy rainfall record for northeastern South Africa based on carbon isotope analysis of four baobab ( Adansonia digitata L.) trees shows centennial and decadal scale variability over the last 1,000 years. The record is in good agreement with a 200-year tree ring record from Zimbabwe, and it indicates the existence of a rainfall dipole between the summer and winter rainfall areas of South Africa. The wettest period was c. AD 1075 in the Medieval Warm Period, and the driest periods were c. AD 1635, c. AD 1695 and c. AD1805 during the Little Ice Age. Decadal-scale variability suggests that the rainfall forcing mechanisms are a complex interaction between proximal and distal factors. Periods of higher rainfall are significantly associated with lower sea-surface temperatures in the Agulhas Current core region and a negative Dipole Moment Index in the Indian Ocean. The correlation between rainfall and the El Niño/Southern Oscillation Index is non-static. Wetter conditions are associated with predominantly El Niño conditions over most of the record, but since about AD 1970 this relationship inverted and wet conditions are currently associated with la Nina conditions. The effect of both proximal and distal oceanic influences are insufficient to explain the rainfall regime shift between the Medieval Warm Period and the Little Ice Age, and the evidence suggests that this was the result of a northward shift of the subtropical westerlies rather than a southward shift of the Intertropical Convergence Zone

Neutrino oscillations and rare processes in models with a small extra dimension

We discuss Dirac neutrino masses and mixings in a scenario where both the standard model fermions and right handed neutrinos are bulk fields in a non-factorizable geometry in five dimensions. We show how the atmospheric and solar neutrino anomalies can be satisfactorily resolved, and in particular how bimaximal mixing is realized. We also consider rare processes such as neutron-antineutron oscillations and mu --> e + gamma, which may occur at an observable rate.Comment: 11 pages, LaTeX, 1 figure, comment and references adde

Past environmental proxies from the Middle Stone Age at Sibudu, Kwazulu-Natal, South Africa

Middle Stone Age technological and behavioural developments in southern Africa are central to understanding the emergence of modern humans, and elucidating the role of environmental change in this trajectory is dependent on emerging palaeoclimatic reconstructions. Climate proxies from Middle Stone Age sites are often poorly preserved, coarsely resolved or subject to anthropogenic selection and are not considered in favour of global environmental proxies despite the fact that the modern climate regimes at the relevant archaeological sites differ profoundly. Sibudu has a well-preserved Middle Stone Age sequence that has yielded abundant palaeoclimate proxy data. Isotopic analysis of charcoal, charcoal anatomy and species representation, macro- and micro-faunal remains, sediment texture, mineralogy and magnetic susceptibility, pollen and macrobotanical remains provide evidence for the environmental succession specific to this site. The isotopic data suggest that archaeological charcoal was not significantly post-depositionally altered. During the Howiesons Poort (65–62 ka) the local environment was thickly forested, moist and more humid than during the 58 ka occupations. The environment changes during the post-Howiesons Poort occupation (~58 ka) into the late MSA occupation (~48 ka); conditions became drier and colder than present with vegetation shifting to open savanna grassland or woodlands.Les évolutions technologiques et comportementales du Middle Stone Age dans le sud de l’Afrique sont essentielles pour comprendre l’émergence de l’Homme moderne, et la compréhension du rôle des changements environnementaux dans cette trajectoire dépend des reconstitutions paléo-climatiques émergentes. Les données indirectes liées au climat du MSA sont souvent mal conservées, de résolution grossière ou soumis à une sélection d’origine anthropique et sont abandonnées au profit des données indirectes liées aux conditions environnementales globales, en dépit du fait que les régimes climatiques modernes sur les sites archéologiques étudiés diffèrent profondément. Sibudu a une séquence bien conservée du Middle Stone Age qui a fournit d’abondantes données paléoclimatiques indirectes. L’analyse isotopique de charbons de bois, l’anatomie du charbon de bois et la représentation des espèces, des restes de faunes macroscopiques et microscopiques, la texture des sédiments, la minéralogie et la susceptibilité magnétique, le pollen et les restes macrobotaniques fournissent des indices de l’évolution de l’environnement spécifique à ce site. Au cours de la période Howiesons Poort (65–62 ka), l’environnement local est couvert de forêts épaisses et humide, plus humide encore lors des occupations de 58 ka. L’environnement change au cours de l’occupation post-Howiesons Poort (~ 58 ka) jusqu’a la fin de l’occupation MSA (~ 48 ka) : il devient plus sec et plus froid qu’à présent et la végétation se mue en grande savane herbeuse ou boisée.Palaeo-Anthropological Scientific Trust (PAST), the National Research Foundation (NRF), the Council for Scientific and Industrial Research (CSIR) and the University of the Witwatersrand.http://www.african-archaeology.dehb201

Final radiocarbon investigation of Platland tree, the biggest African baobab

Author Posting. © Studia Chemia, 2017. This article is posted here by permission of Studia Chemia for personal use, not for redistribution. The definitive version was published in Studia Universitatis Babes-Bolyai, Seria Chemia 62, no. 2, Tom 2 (2017): 347-354, doi:10.24193/subbchem.2017.2.27.The article discloses the main results of our new investigation of Platland tree, a.k.a. Sunland baobab, the largest known African baobab. Our recent research was motivated by the three successive splits of 2016 and 2017, which determined the collapse and demise of the stems that have built the main unit of the tree. According to our new findings concerning the architecture of large and old baobabs, we established that Platland tree has a double closed-ring shaped structure and consists of two units/rings that close two separate false cavities. The larger unit was composed of five fused stems, out of which four toppled and died, while the fifth stem is already broken. The smaller unit, which is still standing, consists of three fused stems. We also determined that the larger unit had an age of 800 yr, while the smaller unit is 1100 yr old.The research was funded by the Romanian Ministry of Scientific Research CNCS-UEFISCDI under grant PN-II-ID-PCE-2013-76

Exposure to substance use in the social environment : the experiences of adolescents in the Tshwane Metropole

The premise of this study is that if exposure to substance use in the social environment of adolescents is understood, macro interventions could be recommended to promote adolescents’ right to live in a safe and sustainable environment. The aim of the study was to explore adolescents’ experiences of exposure to substance use in their social environment, other than the home. A qualitative research approach was adopted and 40 semi-structured interviews were conducted. Adolescent participants, of both genders between 11 and 18 years, were recruited across the Tshwane Metropole. The Social Learning Theory underpinned this study as it offers concepts and principles for understanding how social environmental factors impact on adolescents’ behaviour. Key findings indicated that exposure to substance use is highly prevalent amongst adolescents in the Tshwane Metropole and could be normalised in their social reality. Recommendations are offered for appropriate macro interventions in line with a developmental approach.http://www.uj.ac.za/EN/Faculties/humanities/departments/socialwork/TheSocialWorkPractionerResearcherJournal/Pages/home.aspxam2016Social Work and Criminolog