The effect of pictorial depth information on projected size judgements

When full depth cues are available, size judgements are dominated by physical size. However, with reduced depth cues, size judgements are less influenced by physical size and more influenced by projected size. This study reduces depth cues further than previous size judgement studies, by manipulating monocularly presented pictorial depth cues only. Participants were monocularly presented with two shapes against a background of zero (control), one, two or three pictorial depth cues. Each cue was added progressively in the following order: height in the visual field, linear perspective, and texture gradient. Participants made a „same-different? judgement regarding the projected size of the two shapes, i.e. ignoring any depth cues. As expected, accuracy increased and response times decreased as the ratio between the projected size of the two shapes increased (range of projected size ratios, 1:1 to 1:5). In addition, with the exception of the larger size ratios (1:4 and 1:5), detection of projected size difference was poorer as depth cues were added. One-cue and two-cue conditions had the most weighting in this performance decrement, with little weighting from the three-cue condition. We conclude that even minimal depth information is difficult to inhibit. This indicates that depth perception requires little focussed attention

Totemic outsiders : ontological transformation among the Makushi

Funding: This research was funded by the American Philosophical Society (Lewis and Clark Fund), the Central States Anthropological Society (Leslie A. White Award), and Tulane University (Roger Thayer Stone Center for Latin American Studies, School of Liberal Arts, and Department of Anthropology).This article examines how sociological totemism mediates the co-existence of animism and an emerging naturalism among the Makushi in Surama Village (Guyana) within contexts of interactions with outsiders. Since the 1830s, such contexts have varied from missionization to eco-tourism, which Surama developed in the 1990s and which has since significantly increased. Eco-tourism currently facilitates access to employment, goods, outside knowledge, and international allies in Surama. In the present, villagers seek to fête and propitiate the leaders of outside groups and organizations to ensure the continued provision of these desiderata. Such practices are linked to shamanic relations with the ‘masters’ or ‘owners’ of animals, plants, and other aspects of the landscape. This article argues that these notions of mastery and ownership produce totemic homologies when applied to the intra-social relations of outsiders in Surama. The resulting homologies facilitate the emergence of a nascent naturalism that indicates ongoing ontological transformation in Surama.Publisher PDFPeer reviewe

Warfare and Shamanism in Amazonia

Book review of Warfare and Shamanism in Amazonia. Carlos Fausto. Translated by David Rodgers. New York: Cambridge University Press. 2012. xv + 347 pp., maps, illustrations, footnotes, bibliography, annex, index. USD $99.00 (hardcover). ISBN: 978-1-107-02006-

Transgenic approaches for the investigation of putative airway stem cells as potential targets for gene correction therapy

Since the discovery of the CFTR gene over a decade ago, Cystic Fibrosis (CF) has been regarded as amenable to intervention by gene therapy. The ultimate aim of gene therapy must be the correction, within cells capable of repopulating the tissue, of the genetic defect in its chromosomal context. Towards that end, a mouse model designed to evaluate the efficiency of gene correction was created, and a transgenic approach was taken to the investigation of a putative progenitor cell population in the adult murine respiratory tract. Before gene correction systems can be considered as valid therapeutic agents, their utility in the cells and tissues of living animals must be demonstrated. Thus, an in vivo system permitting the simple quantification of correction frequency in a wide range of tissues would be a valuable resource for the gene correction community. The generation and analysis of a transgenic mouse carrying an inactivated, but potentially correctable, reporter transgene is described. The full potential of a gene correction strategy to provide a single-dose, permanent solution to a genetically-diseased tissue will only be realised once the therapy is able to target resident stem cells. For CF lung disease, this will require the prior identification of stem cells in the respiratory epithelium. Previous work has indicated that potential stem cells are spatially coincident with small groups of cells expressing high levels of keratin 5 (K5) protein in the proximal murine trachea. In order to investigate lineage arising from this putative stem cell niche, transgenic mice have been generated which express an inducible form of Cre recombinase from the K5 promoter. Preliminary experiments demonstrate recombination of a conditional reporter gene after induction of Cre activity in K5-expressing tissue. Comparison of the inducible system with a constitutive K5 promoter-driven Cre line validated the choice of the former, as the clarity of data obtained from the conventional system was undermined as a result of K5 promoter activity causing reporter gene activation prior to the onset ofthe experiment. In the course of these studies it became evident that the conventional, constitutive Cre line gave rise to segregating patterns of reporter gene activation. While some mice displayed the expected K5-derived expression profile, other animals demonstrated ubiquitous expression. Universal activation of the conditional reporter was detected only in animals derived from females carrying the Cre transgene, and was found to be the result of unanticipated production of Cre protein in the maternal germline. This transgenic line is unusual and valuable in offering a choice of tissuespecific and generalised recombination of floxed alleles

Essays on the Economics of Vaccination

I examine vaccination behavior during a measles outbreak. By abandoning the rationalexpectations framework, I develop a model of vaccine behavior which recreates empirically observed vaccine hesitancy, as well as vaccination spikes during an outbreak. I use an agent-based model to simulate disease spread and agent behavior in a measles outbreak, in which rational agents minimize their expected costs by choosing their vaccination state. I allow some agents to instead use a heuristic, and others to have misinformation regarding vaccine risks, and finds that both reduce welfare. Including a social network has an ambiguous effect, as using more relevant local data allows agents to better estimate their risk from disease, but the same social network amplifies the impact of misinformation. I then examine a series of regulator interventions, and find that using a social media campaign to change agent’s perceptions of their peers’ views is the most cost-effective intervention. This presents regulators with a new framework with which to understand vaccine hesitancy, and an expanded menu of options to employ in the event of an outbreak

Guns and Sorcery: Raiding, Trading, and Kanaima among the Makushi

Raiding, trading, and sorcery are historically-interrelated phenomena among the Makushi Amerindians in Guyana. Colonial documents reveal that the Makushi were heavily targeted during the eighteenth and early nineteenth centuries by Luso-Brazilian and Amerindian slavers. The form of such slaving frequently fluctuated between raiding and trading and formed a nexus around which practices of sorcery came to be centred. A connexion between the historical positions of the Makushi as victims of slaving and practitioners of kanaima sorcery has been identified by Neil Whitehead, who hypothesized that kanaima practices gained socially-sanctioned applications as the introduction of guns led to transformations in traditional patterns of Amerindian warfare in the region. However, although these changes led to new defencive applications for kanaima violence, there is evidence that warriors were susceptible to kanaima manipulations and that sorceric defences against external predation expanded the potential scope of internal predation

Amerindians in the Eighteenth Century Plantation System of the Guianas

Dutch relations with Amerindian societies in their South American colonies began in the early seventeenth century. This contact increased during the eighteenth century, when Amerindians were slaves, slavers, and plantation enforcers for the Dutch. These roles transitioned over time and unevenly extended across the Amerindian societies within the Dutch colonies. The early configuration of the Dutch colonies relied upon Amerindians for trade. With the further development of the Dutch colonies, some societies were repeatedly the targets of slaving while other societies were allied with the Dutch and acted as slavers. Later, with the large-scale introduction of African slaves, some Amerindians became plantation enforcers. Amerindian enforcement of the plantation system was gradually institutionalized during the late eighteenth century. By the nineteenth century, Amerindians had become the integral component in Dutch efforts to prevent uprisings by African-descent slaves, to pursue runaway slaves, to attack maroon camps, and to stabilize aplantation system at risk of open rebellion. With a primary emphasis on Essequibo andDemerara, this article will delineate the roles of Amerindians within the plantation system ofthe Guianas in the eighteenth centur

Analysis of Flow Competence in an Alluvial Gravel Bed Stream, Dupuyer Creek, Montana

Critical shear stress and unit discharge flow competence models were tested against coarse bed load data from Dupuyer Creek, Montana, United States. Maximum particle sizes sampled (Dmax) and D-50 to D-90 percentiles in the bed load grain size distribution were well correlated with both shear stress and unit discharge. Bed load grain sizes became coarser with increasing flow strength. For the D-max curve, Shields dimensionless parameter for the surface D-50 was estimated at 0.044, and the exponent for relative particle size (D-i/ D-50) was - 0.59. In the unit discharge criterion the critical flow to entrain the surface D50 was poorly predicted. Flow competence relationships based on D-max are prone to the influence of outliers and sample mass variability. The mean of the three largest particles, D-max ( 3), is more sensitive to changes in flow strength than the D-50 to D-90 bed load grain sizes, and may represent a good compromise

Microbial carbon mineralization in tropical lowland and montane forest soils of Peru

Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g., "positive priming effects" that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding (13)C labeled substrates, as surrogates of plant inputs, to soils from an elevation gradient of tropical lowland and montane forests. We hypothesized that priming effects would increase with elevation due to increasing microbial nitrogen limitation, and that microbial community composition would strongly influence the magnitude of priming effects. Quantifying the sources of respired C (substrate or soil organic matter) in response to substrate addition revealed no consistent patterns in priming effects with elevation. Instead we found that substrate quality (complexity and nitrogen content) was the dominant factor controlling priming effects. For example a nitrogenous substrate induced a large increase in soil organic matter mineralization whilst a complex C substrate caused negligible change. Differences in the functional capacity of specific microbial groups, rather than microbial community composition per se, were responsible for these substrate-driven differences in priming effects. Our findings suggest that the microbial pathways by which plant inputs and soil organic matter are mineralized are determined primarily by the quality of plant inputs and the functional capacity of microbial taxa, rather than the abiotic properties of the soil. Changes in the complexity and stoichiometry of plant inputs to soil in response to climate change may therefore be important in regulating soil C dynamics in tropical forest soils.This study was financed by the UK Natural Environment Research Council (NERC) grant NE/G018278/1 and is a product of the Andes Biodiversity and Ecosystem Research Group consortium (www.andesconservation.org); Patrick Meir was also supported by ARC FT110100457