1977 performance of commercial soybeans in Illinois / 1152

Chiefly tables.Cover title

Negotiating freedom: the free black farmers of Jonkershoek, 1697-1710

During the late seventeenth century, a section of Cape Town's ‘free black' (vrijzwart) population, a group comprised primarily of formerly enslaved people, took up farming in the Jonkershoek Valley of Stellenbosch. Despite initial prosperity, these free black farmers ceased to exist as an independent socio-political entity by the 1720s. Scholars of the Dutch Cape Colony, such as Hermann Giliomee and Karel Schoeman, have attributed this decline to a lack of capital, high labour costs, the distance from the market and the specialised nature of wheat farming at the Cape. Yet white farmers, confronted by similar obstacles, managed to transcend them and coalesce into a permanent agrarian class. This thesis attempts to account for this disparity by examining hitherto unexplored socio-economic factors that contributed to the rise and fall of free black farmers in Jonkershoek, particularly the patronage network between the free blacks and the Van der Stel dynasty. An extensive perusal of archival sources and secondary literature has facilitated two key observations. Firstly, the influx of free black farmers into Jonkershoek was contingent on the direct intervention of Governor Simon van der Stel, who hoped to supplant the recalcitrant white farmers with a more compliant group of agriculturalists. Imperatively, Van der Stel's policy of encouraging free black settlement in Jonkershoek via land grants was maintained by his son and successor, Willem Adriaan van der Stel. Secondly, the association between the Van der Stels and the free black farmers left the latter vulnerable to economic exclusion when Willem Adriaan van der Stel became embroiled in a dispute with the white settler faction and was subsequently dismissed on corruption charges in 1707. These findings demonstrate that, despite their status as free individuals, free black farmers occupied a precarious position within Cape society and were constantly compelled to negotiate their freedom

The robustness of preferences during a crisis: The case of COVID-19

We investigate how preferences have been affected by exposure to the COVID-19 crisis. Our main contributions are: first, our participant pool consists of a large general population sample; second, we elicited a wide range of preferences (risk, time, ambiguity, and social preferences) using different incentivized experimental tasks; third, we elicited preferences before the onset of the crises and in three additional waves during the crises over a time period of more than a year, allowing us to investigate both short-term and medium-term preference responses; fourth, besides the measurement of causal effects of the crisis, we also analyze within each wave during the crisis, how differential exposure to the crisis in the health and financial domain affects preferences. We find that preferences remain remarkably stable during the crisis. Comparing them before the start and during the crisis, we do not observe robust differences in any of the elicited preferences. Moreover, individual differences in the exposure to the crisis at best show only weak effects in the financial domain

Analysis of Deformation Data at Parkfield, California: Detection of a Long-Term Strain Transient

Analysis of more than a decade of high-quality data, particularly those from the two-color electronic distance meter (EDM), in the Parkfield, California, area reveals a significant transient in slip rate along the San Andreas Fault. This transient consists of an increase in fault slip rate of 3.3 ± 0.9 mm/yr during 1993.0 to 1998.0. The most reliable fault creep instruments show a comparable increase in slip rate, suggesting that the deformation is localized to the fault which breaks the surface. There was also an increase in precipitation around 1993. It is unlikely, however, that this anomaly is due directly to hydrology, as its spatial distribution is what would be expected for increased slip on the San Andreas Fault. The increase in slip rate corresponds temporally to a dramatic increase in seismicity, including the four largest earthquakes in the period 1984-1999 that occurred along a 6-km segment of the fault just to the north of the EDM network. There was also a previously reported anomaly in borehole shear strain [Gwyther et al., 1996] that closely corresponds temporally to the transient in EDM data. Solely on the basis of EDM data the transient can be modeled as a slip event on a 10-km-long segment of the fault. The calculated shear strains from this model, however, are not consistent with the observed ones. A compatible model can be found if there is increased aseismic slip to the northwest in conjunction with the four earthquakes. Support for this northwestern slip is provided by a recent study of slip rate based on microearthquake activity. We speculate that this northwestern event served to load the fault to the southeast, with the stress being partially released by the observed slip

IVOA Recommendation: VOResource: an XML Encoding Schema for Resource Metadata Version 1.03

This document describes an XML encoding standard for IVOA Resource Metadata, referred to as VOResource. This schema is primarily intended to support interoperable registries used for discovering resources; however, any application that needs to describe resources may use this schema. In this document, we define the types and elements that make up the schema as representations of metadata terms defined in the IVOA standard, Resource Metadata for the Virtual Observatory [Hanicsh et al. 2004]. We also describe the general model for the schema and explain how it may be extended to add new metadata terms and describe more specific types of resources

Beyond Time and Space:The Effect of a Lateralized Sustained Attention Task and Brain Stimulation on Spatial and Selective Attention

The Theory of Visual Attention (TVA) provides a mathematical formalisation of the “biased competition” account of visual attention. Applying this model to individual performance in a free recall task allows the estimation of 5 independent attentional parameters: visual short-term memory (VSTM) capacity, speed of information processing, perceptual threshold of visual detection; attentional weights representing spatial distribution of attention (spatial bias), and the top-down selectivity index. While the TVA focuses on selection in space, complementary accounts of attention describe how attention is maintained over time, and how temporal processes interact with selection. A growing body of evidence indicates that different facets of attention interact and share common neural substrates. The aim of the current study was to modulate a spatial attentional bias via transfer effects, based on a mechanistic understanding of the interplay between spatial, selective and temporal aspects of attention. Specifically, we examined here: (i) whether a single administration of a lateralized sustained attention task could prime spatial orienting and lead to transferable changes in attentional weights (assigned to the left vs right hemi-field) and/or other attentional parameters assessed within the framework of TVA (Experiment 1); (ii) whether the effects of such spatial-priming on TVA parameters could be further enhanced by bi-parietal high frequency transcranial random noise stimulation (tRNS) (Experiment 2). Our results demonstrate that spatial attentional bias, as assessed within the TVA framework, was primed by sustaining attention towards the right hemi-field, but this spatial-priming effect did not occur when sustaining attention towards the left. Furthermore, we show that bi-parietal high-frequency tRNS combined with the rightward spatial-priming resulted in an increased attentional selectivity. To conclude, we present a novel, theory-driven method for attentional modulation providing important insights into how the spatial and temporal processes in attention interact with attentional selection

Chaotic Inflationary Universe on Brane

The chaotic inflationary model of the early universe, proposed by Linde is explored in the brane world considering matter described by a minimally coupled self interacting scalar field. We obtain cosmological solutions which admit evolution of a universe either from a singularity or without a singularity. It is found that a very weakly coupled self-interacting scalar field is necessary for a quartic type potential in the brane world model compared to that necessary in general relativity. In the brane world sufficient inflation may be obtained even with an initial scalar field having value less than the Planck scale. It is found that if the universe is kinetic energy dominated to begin with, it transits to an inflationary stage subsequently.Comment: 13 pages, no fig., accepted in Physical Review

The Structure of the Big Bang from Higher-Dimensional Embeddings

We give relations for the embedding of spatially-flat Friedmann-Robertson-Walker cosmological models of Einstein's theory in flat manifolds of the type used in Kaluza-Klein theory. We present embedding diagrams that depict different 4D universes as hypersurfaces in a higher dimensional flat manifold. The morphology of the hypersurfaces is found to depend on the equation of state of the matter. The hypersurfaces possess a line-like curvature singularity infinitesimally close to the $t = 0^+$ 3-surface, where $t$ is the time expired since the big bang. The family of timelike comoving geodesics on any given hypersurface is found to have a caustic on the singular line, which we conclude is the 5D position of the point-like big bang.Comment: 11 pages, 5 figures, revtex4, accepted in Class. Quant. Gra