Contrast sensitivity of insect motion detectors to natural images

How do animals regulate self-movement despite large variation in the luminance contrast of the environment? Insects are capable of regulating flight speed based on the velocity of image motion, but the mechanisms for this are unclear. The Hassenstein–Reichardt correlator model and elaborations can accurately predict responses of motion detecting neurons under many conditions but fail to explain the apparent lack of spatial pattern and contrast dependence observed in freely flying bees and flies. To investigate this apparent discrepancy, we recorded intracellularly from horizontal-sensitive (HS) motion detecting neurons in the hoverfly while displaying moving images of natural environments. Contrary to results obtained with grating patterns, we show these neurons encode the velocity of natural images largely independently of the particular image used despite a threefold range of contrast. This invariance in response to natural images is observed in both strongly and minimally motion-adapted neurons but is sensitive to artificial manipulations in contrast. Current models of these cells account for some, but not all, of the observed insensitivity to image contrast. We conclude that fly visual processing may be matched to commonalities between natural scenes, enabling accurate estimates of velocity largely independent of the particular scene

Coming to terms with our history

Many historians condemn most of those who have led our nation since its first settlement over 400 years ago, focusing only on their roles in perpetuating those institutions. They apply today's standards of morality and concepts of political correctness to people who grew up in an entirely different era, and whose views of the world were molded by personal experiences, conventional wisdom and moral standards far different from those of today. The result is that most of our forebears – including some of our historically most revered "founding fathers" – are now being characterized as evil and misguided persons, with little or no acknowledgment that they acted according to the widely accepted standards of their day, and that they made many positive contributions to our world

Celebrating Macedonia Baptist Church the Edgefield Academy and the Paris and Andrew Simkins families

This gives a history of Macedonia Baptist Church the Edgefield Academy and the Paris and Andrew Simkins families

Celebrating Holly Hill

This gives a history of Holly Hill, a house in Edgefield, South Carolina

2010 Fall meeting of the Edgefield County Historical Society

This is a biography of Braidwood Lester Holmes

Young climate protesters' mobilization availability: Climate marches and school strikes compared

This the final version. Available on open access from Frontiers Media via the DOI in this recordData Availability Statement: The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: The 2009 climate march data used for this study can be found on the Data Archiving and Networked services website, available at: https://easy.dans.knaw.nl/ui/datasets/id/easy-dataset:110989. The GCS data is available on request from the corresponding author.Although there is a developing strand of literature on young people’s participation in environmental activism, there have been few systematic comparisons of their participation in different forms of environmental activism. This article compares the participation of young people and their older counterparts in climate change marches and Global Climate Strikes (GCSs). The agential and structural factors that draw people into protest participation are, in general terms, well recognized. However, it is also recognized that the factors that lead to particular types of protest on certain issues might not be the same as those that lead to different types of protest on different issues. In this article, we keep the protest issue constant (climate change), and make comparisons across different forms of climate protest (marches and school strikes). We coin the term ‘mobilization availability’, which is a useful way to understand why young people are differentially mobilized into different types of climate change protest. Our notion of mobilization availability invites scholars to consider the importance of the interplay of the supply and demand for protest in understanding who protests and why. We use data collected using standardized protest survey data (n=643). In order to account for response rate bias, which is an acute problem when studying young people’s protest survey responses, we weighted the data using propensity score adjustments. We find that the youth-oriented supply of protest evoked by GCS mobilized higher numbers of young people into climate protest than did the more adult-dominated climate marches. GCS did this by providing accessible forms of protest, which reduced the degree of structural availability required to encourage young people to protest on the streets, and by emotionally engaging them. Indeed, the young people we surveyed at the GCSs were considerably more angry than their adult counterparts, and also angrier than young people on other climate protests. Our conceptual and empirical innovations make this paper an important contribution to the literature on young people’s political participation.Economic and Social Research Council (ESRC)British Academ