The influence of grazing on surface climatological variables of tallgrass prairie

Mass and energy exchange between most grassland canopies and the atmosphere are mediated by grazing activities. Ambient temperatures can be increased or decreased by grazers. Data have been assembled from simulated grazing experiments on Konza Prairie Research Natural Area and observations on adjacent pastures grazed by cattle show significant changes in primary production, nutrient content, and bidirectional reflectance characteristics as a function of grazing intensity. The purpose of this research was to provide algorithms that would allow incorporation of grazing effects into models of energy budgets using remote sensing procedures. The approach involved: (1) linking empirical measurements of plant biomass and grazing intensities to remotely sensed canopy reflectance, and (2) using a higher resolution, mechanistic grazing model to derive plant ecophysiological parameters that influence reflectance and other surface climatological variables

Exploring the mechanisms of allelopathic interaction in the invasive annual plant, Phyllanthus urinaria

The belowground mechanisms facilitating invasion and proliferation of non-native plant species into natural communities are of critical importance for understanding plant invasions. Research on allelopathy suggests that some exotic plant species produce compounds via root exudates that may suppress or inhibit the growth of neighboring plants, but the specific mechanisms and consequences of these plant-chemical interactions remain elusive. In an effort to understand the abiotic and biotic factors governing allelopathic activity, a two-part greenhouse experiment was designed to examine plant-soil interactions of the invasive euphorb, Phyllanthus urinaria, and the residual soil effects of these interactions on subsequent growth of a target species, Brassica rapa. Our results confirmed that plant-soil feedback from Phyllanthus negatively influenced growth of Brassica and the effect was proportional to the Phyllanthus biomass. However, it is unclear whether the mechanism responsible for this negative effect is associated with chemical suppression (i.e., allelopathy) or with depletion of soil nutrients (i.e., competition). In addition to screening for phyto-toxic compounds, soil analysis of macro- and micro- nutrient levels may be necessary to differentiate between plant strategies that create chemical interference vs. those that influence resource availability. Description and definition of these plant mechanisms may provide useful insight into understanding the factors that enable alien species to invade and successfully coexist in natural communities

Association patterns and foraging behaviour in natural and artificial guppy shoals

Animal groups are often nonrandom assemblages of individuals that tend to be assorted by factors such as sex, body size, relatedness and familiarity. Laboratory studies using fish have shown that familiarity among shoal members confers a number of benefits to individuals, such as increased foraging success. However, it is unclear whether fish in natural shoals obtain these benefits through association with familiars. We investigated whether naturally occurring shoals of guppies, Poecilia reticulata, are more adept at learning a novel foraging task than artificial (in which we selected shoal members randomly) shoals. We used social network analysis to compare the structures of natural and artificial shoals and examined whether shoal organization predicts patterns of foraging behaviour. Fish in natural shoals benefited from increased success in the novel foraging task compared with fish in artificial shoals. Individuals in natural shoals showed a reduced latency to approach the novel feeder, followed more and formed smaller subgroups compared to artificial shoals. Our findings show that fish in natural shoals do gain foraging benefits and that this may be facilitated by a reduced perception of risk among familiarized individuals and/or enhanced social learning mediated by following other individuals and small group sizes. Although the structure of shoals was stable over time, we found no direct relationship between shoal social structure and patterns of foraging behaviour

Abortion Decisions as Humanizing Acts: The Application of Ambivalent Sexism and Objectification to Women-Centered Anti-Abortion Rhetoric

Women-centered anti-abortion rhetoric, grounded in ostensibly positive beliefs that pregnant people are precious objects who must be protected from having abortions, has proliferated anti-abortion activism and legislation. However, abortion stigma, marked by negative perceptions of people who terminate pregnancies, is the most widely used theoretical tool for understanding the social and psychological implications of abortion. In this article, we first integrate these two seemingly contradictory perspectives on abortion through the lens of ambivalent sexism theory. We then argue that ambivalent sexism paves the way for objectifying perceptions and treatment of pregnant people; specifically, our typology of reproductive objectification provides a tool for exploring how the abortion decision-making of pregnant people is undermined. Through this lens, abortion decisions can represent a subversion of these portrayals and treatment by affirming people who seek and have abortions as whole human beings. Throughout, we aim to counter White supremacy and cisheteropatriarchy, which have marked public discourse and psychological research on abortion. Finally, using this reproductive objectification framework, recommendations for clinicians and researchers are provided

The Contribution of the Cosmological Constant to the Relativistic Bending of Light Revisited

We study the effect of the cosmological constant $\Lambda$ on the bending of light by a concentrated spherically symmetric mass. Contrarily to previous claims, we show that when the Schwarzschild-de Sitter geometry is taken into account, $\Lambda$ does indeed contribute to the bending.Comment: 5 pages, 2 figure