A delay differential model of ENSO variability: Parametric instability and the distribution of extremes

We consider a delay differential equation (DDE) model for El-Nino Southern Oscillation (ENSO) variability. The model combines two key mechanisms that participate in ENSO dynamics: delayed negative feedback and seasonal forcing. We perform stability analyses of the model in the three-dimensional space of its physically relevant parameters. Our results illustrate the role of these three parameters: strength of seasonal forcing $b$, atmosphere-ocean coupling $\kappa$, and propagation period $\tau$ of oceanic waves across the Tropical Pacific. Two regimes of variability, stable and unstable, are separated by a sharp neutral curve in the $(b,\tau)$ plane at constant $\kappa$. The detailed structure of the neutral curve becomes very irregular and possibly fractal, while individual trajectories within the unstable region become highly complex and possibly chaotic, as the atmosphere-ocean coupling $\kappa$ increases. In the unstable regime, spontaneous transitions occur in the mean ``temperature'' ({\it i.e.}, thermocline depth), period, and extreme annual values, for purely periodic, seasonal forcing. The model reproduces the Devil's bleachers characterizing other ENSO models, such as nonlinear, coupled systems of partial differential equations; some of the features of this behavior have been documented in general circulation models, as well as in observations. We expect, therefore, similar behavior in much more detailed and realistic models, where it is harder to describe its causes as completely.Comment: 22 pages, 9 figure

The role of central bank transparency for guiding private sector forecasts

There is a broad consensus in the literature that costs of information processing and acquisition may generate costly disagreements in expectations among economic agents, and that central banks may play a central role in reducing such dispersion in expectations. This paper analyses empirically whether enhanced central bank transparency lowers dispersion among professional forecasters of key economic variables, using a large set of proxies for central bank transparency in 12 advanced economies. It finds evidence for a significant and sizeable effect of central bank transparency on forecast dispersion, be it by means of announcing a quantified inflation objective, other forms of communication, or by publishing central banks’ inflation and output forecasts. However, there also appear to be limits to central bank transparency, with decreasing marginal returns to enhancing (economic) transparency, and given our findings that disagreement among inflation expectations in the general public is not affected by the various central bank transparency measures analyzed in this paper. JEL Classification: E37, E52, C53central bank communication, central banking, disagreement, forecasting, inflation targeting, monetary policy, survey expectations, transparency

All Things Being Equal: Land Ownership and Ethnicity in Rural Canada, 1901

The relationship between ethnicity and land ownership in rural Canada is explored here using the new national sample of the 1901 census developed by the Canadian Families Project. The data offer the first comparison, at a household level, of the factors affecting land ownership throughout the country. Multivariate regressions confirm recent findings that ethnicity was a relatively unimportant determinant of the variation in land ownership at the national level, although it did have an impact on access to farmland in the West. Like the findings of Gordon Darroch and Lee Soltow for Ontario in 1871, the 1901 data indicate that life cycle continued to be the most decisive predictor of farm size.Cette étude se penche sur la relation entre l’ethnicité et la propriété foncière dans le Canada rural à l’aide du nouvel échantillon national du recensement de 1901 réuni par le Projet de recherche sur les familles canadiennes. Les données offrent la première comparaison, au niveau des ménages, des facteurs influant sur l’accession à la propriété foncière à travers le pays. Des régressions multivariées confirment les résultats récents selon lesquels l’ethnicité était un déterminant relativement peu important de la variation de l’accession à la propriété foncière à l’échelle nationale, quoiqu’elle ait eu un impact sur l’accès aux terres agricoles dans l’Ouest. Comme les résultats obtenus par Gordon Darroch et Lee Soltow pour l’Ontario en 1871, les données de 1901 indiquent que le cycle de vie demeurait le prédicteur le plus décisif de la taille des exploitations agricoles

Groupness in Preverbal Infants: Proof of Concept

Infant sociability is generally conceived in terms of dyadic capacities and behaviors. Recently, quantitative evidence has been published to support arguments that infants achieve a criterion for groupness: the capacity to interact simultaneously with two others. Such studies equate this capacity with alternating dyadic acts to the two other members of an interacting trio. Here we propose a stricter threefold criterion for infant groupness, of which the crux is whether the social behavior of an infant at time B is shown to be influenced by what two or more group-members were previously doing at time A. We test the viability of this conceptualization: (a) through its justification of the novel laboratory procedure of studying infant sociability in infant–peer quartets (rather than trios); and, (b) in an analysis of a pilot study of gaze-behavior recorded in 5-min interactions among two quartets of infants aged 6–9 months. We call this a ‘proof of concept’ because our aim is to show that infants are capable of groupness, when groupness is conceptualized in a supra-dyadic way—not that all infants will manifest it, nor that all conditions will produce it, nor that it is commonplace in infants’ everyday lives. We found that both quartets did achieve the minimum criterion of groupness that we propose: mutual gaze predicting coordinated gaze (where two babies, A and B, are looking at each other, and B is then looked at by C, and sometimes D) more strongly than the reverse. There was a significant absence of ‘parallel mutual gaze,’ where the four babies pair off. We conclude that, under specific conditions, preverbal infants can manifest supra-dyadic groupness. Infants’ capacities to exhibit groupness by 9 months of age, and the paucity of parallel mutual gaze in our data, run counter to the assumption that infant sociability, when in groups, is always generated by a dyadic program. Our conceptualization and demonstration of groupness in 8-month-olds thus opens a host of empirical, theoretical, and practical questions about the sociability and care of young babies.The collection of data was funded through a grant from the British Academy: Is Group-Membership Basic to Infant Mental Health? Establishing a Method British Academy Grant 2008-97469 (A$16,100) (C. Urwin, J. M. Selby, BB). The research assistance for data-coding was funded by Charles Sturt Universit

The world's highest vascular epiphytes found in the Peruvian Andes

The highest elevation epiphytic vascular plant flora ever recorded on a worldwide basis is described from the Cordillera Vilcabamba, southern Peruvian Andes. Three species of fern (Melpomene, Polypodium: Polypodiaceae) were recorded from Polylepis pepei forests at elevations above 4,250m, with Melpomene peruviana reaching almost 4,550m. A new high-elevation world record for arboreal hemiparasites is also documented, with Tristerix longebracteatus (Loranthaceae) being found at c.4,620m. Climatic conditions of these sites were assessed and are discussed in the light of existing hypotheses on the abiotic conditions limiting epiphytism

Offsets and the Path to Carbon Neutrality in Higher Education and Study Abroad

Professors Paul Sylvester, Early & Middle Grades Education, and Michael Di Giovine, Anthropology, in conversation with Bradley Flamm - Offsets and the Path to Carbon Neutrality in Higher Education and Study Abroa