3,307 research outputs found
Academic Agenda, Goal Setting, and African American Male Student Persistence at a Predominantly Black Institution
Low African American male student graduation rates in the United States have been a concern for higher education administrators, and more strategies to address their challenges are needed. This basic qualitative study addressed the experiences of African American male students who persisted to graduation at a predominantly Black institution in the northeastern United States. The institutional departure model and goal setting theory formed the conceptual framework for the study. Nine African American males who graduated from the institution described their experiences with academic goal setting and a graduation agenda, through one-on-one interviews. Key findings included the challenges of financial concerns, making supportive connections, and being engaged with university life. Goal setting and pursuing a graduation agenda were supported by interacting regularly with diverse faculty and staff, having work study positions, and participating in athletics and student organizations. Moments of individual connection and support from staff and faculty members helped students pursue academic goals. The project constructed to address the gaps is a 3-day professional development curriculum. Professional development is necessary to ensure all members of campus are focused on the orientation of first year students and their families to support retention through graduation. Academic agenda and goal setting can and should occur across campus and in multiple settings. Positive social change implications of the project include increased stakeholder awareness of supports necessary to retain African American male students in predominantly Black institutions
Empirical Comparison of Graph Embeddings for Trust-Based Collaborative Filtering
In this work, we study the utility of graph embeddings to generate latent
user representations for trust-based collaborative filtering. In a cold-start
setting, on three publicly available datasets, we evaluate approaches from four
method families: (i) factorization-based, (ii) random walk-based, (iii) deep
learning-based, and (iv) the Large-scale Information Network Embedding (LINE)
approach. We find that across the four families, random-walk-based approaches
consistently achieve the best accuracy. Besides, they result in highly novel
and diverse recommendations. Furthermore, our results show that the use of
graph embeddings in trust-based collaborative filtering significantly improves
user coverage.Comment: 10 pages, Accepted as a full paper on the 25th International
Symposium on Methodologies for Intelligent Systems (ISMIS'20
Evolution of non-kin cooperation: social assortment by cooperative phenotype in guppies
This is the final version. Available from The Royal Society via the DOI in this record.Data accessibility: The data used in this study are available at the Dryad Digital Repository: doi:10.5061/dryad.js446q8Cooperation among non-kin constitutes a conundrum for evolutionary biology. Theory suggests that
non-kin cooperation can evolve if individuals differ consistently in their cooperative phenotypes and
assort socially by these, such that cooperative individuals interact predominantly with one another.
However, our knowledge of the role of cooperative phenotypes in the social structuring of real-world
animal populations is minimal. In this study, we investigated cooperative phenotypes and their link to
social structure in wild Trinidadian guppies (Poecilia reticulata). We first investigated whether wild
guppies are repeatable in their individual levels of cooperativeness (i.e. have cooperative phenotypes)
and found evidence for this in seven out of eight populations, a result which was mostly driven by
females. We then examined the social network structure of one of these populations where the expected
fitness impact of cooperative contexts is relatively high, and found assortment by cooperativeness, but
not genetic relatedness. In contrast, in accordance with our expectations we did not find assortment by
cooperativeness in a population where the expected fitness impact of cooperative contexts is lower. Our
results provide empirical support for current theory and suggest that assortment by cooperativeness is
important for the evolution and persistence of non-kin cooperation in real-world populations.Leverhulme TrustDanish Council for Independent Researc
Lightweight Interactions for Reciprocal Cooperation in a Social Network Game
The construction of reciprocal relationships requires cooperative
interactions during the initial meetings. However, cooperative behavior with
strangers is risky because the strangers may be exploiters. In this study, we
show that people increase the likelihood of cooperativeness of strangers by
using lightweight non-risky interactions in risky situations based on the
analysis of a social network game (SNG). They can construct reciprocal
relationships in this manner. The interactions involve low-cost signaling
because they are not generated at any cost to the senders and recipients.
Theoretical studies show that low-cost signals are not guaranteed to be
reliable because the low-cost signals from senders can lie at any time.
However, people used low-cost signals to construct reciprocal relationships in
an SNG, which suggests the existence of mechanisms for generating reliable,
low-cost signals in human evolution.Comment: 13 pages, 2 figure
Sequestration of Martian CO2 by mineral carbonation
Carbonation is the water-mediated replacement of silicate minerals, such as olivine, by carbonate, and is commonplace in the Earth’s crust. This reaction can remove significant quantities of CO2 from the atmosphere and store it over geological timescales. Here we present the first direct evidence for CO2 sequestration and storage on Mars by mineral carbonation. Electron beam imaging and analysis show that olivine and a plagioclase feldspar-rich mesostasis in the Lafayette meteorite have been replaced by carbonate. The susceptibility of olivine to replacement was enhanced by the presence of smectite veins along which CO2-rich fluids gained access to grain interiors. Lafayette was partially carbonated during the Amazonian, when liquid water was available intermittently and atmospheric CO2 concentrations were close to their present-day values. Earlier in Mars’ history, when the planet had a much thicker atmosphere and an active hydrosphere, carbonation is likely to have been an effective mechanism for sequestration of CO2
Fitness benefits of prolonged post-reproductive lifespan in women
Most animals reproduce until they die, but in humans, females can survive long after ceasing reproduction. In theory, a prolonged post-reproductive lifespan will evolve when females can gain greater fitness by increasing the success of their offspring than by continuing to breed themselves. Although reproductive success is known to decline in old age, it is unknown whether women gain fitness by prolonging lifespan post-reproduction. Using complete multi-generational demographic records, we show that women with a prolonged post-reproductive lifespan have more grandchildren, and hence greater fitness, in pre-modern populations of both Finns and Canadians. This fitness benefit arises because post-reproductive mothers enhance the lifetime reproductive success of their offspring by allowing them to breed earlier, more frequently and more successfully. Finally, the fitness benefits of prolonged lifespan diminish as the reproductive output of offspring declines. This suggests that in female humans, selection for deferred ageing should wane when one's own offspring become post-reproductive and, correspondingly, we show that rates of female mortality accelerate as their offspring terminate reproduction
Female chacma baboons form strong, equitable, and enduring social bonds
Analyses of the pattern of associations, social interactions, coalitions, and aggression among chacma baboons (Papio hamadryas ursinus) in the Okavango Delta of Botswana over a 16-year period indicate that adult females form close, equitable, supportive, and enduring social relationships. They show strong and stable preferences for close kin, particularly their own mothers and daughters. Females also form strong attachments to unrelated females who are close to their own age and who are likely to be paternal half-sisters. Although absolute rates of aggression among kin are as high as rates of aggression among nonkin, females are more tolerant of close relatives than they are of others with whom they have comparable amounts of contact. These findings complement previous work which indicates that the strength of social bonds enhances the fitness of females in this population and support findings about the structure and function of social bonds in other primate groups
Visual ecology of aphids – a critical review on the role of colours in host finding
We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms.
Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region.
We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours
that are not likely to hold. Finally we also discuss the
implications for developing and optimising strategies
of aphid control and monitoring
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Preservation and recovery of mangrove ecosystem carbon stocks in abandoned shrimp ponds
Mangrove forests capture and store exceptionally large amounts of carbon and are increasingly recognised as an important ecosystem for carbon sequestration. Yet land-use change in the tropics threatens this ecosystem and its critical ‘blue carbon’ (carbon stored in marine and coastal habitats) stores. The expansion of shrimp aquaculture is among the major causes of mangrove loss globally. Here, we assess the impact of mangrove to shrimp pond conversion on ecosystem carbon stocks, and carbon losses and gains over time after ponds are abandoned. Our assessment is based on an intensive field inventory of carbon stocks at a coastal setting in Thailand. We show that although up to 70% of ecosystem carbon is lost when mangroves are converted to shrimp ponds, some abandoned ponds contain deep mangrove soils (>2.5 m) and large carbon reservoirs exceeding 865 t carbon per hectare. We also found a positive recovery trajectory for carbon stocks in the upper soil layer (0-15 cm) of a chronosequence of abandoned ponds, associated with natural mangrove regeneration. Our data suggest that mangrove carbon pools can rebuild in abandoned ponds over time in areas exposed to tidal flushing
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