4,399 research outputs found
Pink landscapes: 1/f spectra of spatial environmental variability and bird community composition
Temporal and spatial environmental variability are predicted to have reddened spectra that reveal increases in variance with the period or length sampled. However, spectral analyses have seldom been performed on ecological data to determine whether these predictions hold true in the case of spatial environmental variability. For a 50 km long continuous transect of 128 point samples across a heterogeneous cultural landscape in the Czech Republic, both habitat composition and bird species composition decomposed by standard ordination techniques did indeed exhibit reddened spectra.
The values of main ordination axes have relationships between log spectral density and log frequency with slopes close to -1, indicating 1/f, or 'pink' noise type of variability that is characterized by scale invariance. However, when habitat composition was controlled for and only residuals for bird species composition were analysed, the spectra revealed a peak at intermediate frequencies, indicating that population processes that structure bird communities but are not directly related to the structure of the environment might have some typical correlation length. Spatial variability of abundances of individual species was mostly reddened as well, but the degree was positively correlated to their total abundance and niche position (strength of species-habitat association). If 'pink' noise type of variability is as generally typical for spatial environmental variability as for temporal variability, the consequences may be profound for patterns of species diversity on different spatial scales, the form of species-area relationships and the distribution of abundances within species ranges
Structure of the species-energy relationship
The relationship between energy availability and species richness (the species-energy relationship) is one of the best documented macroecological phenomena. However, the structure of species distribution along the gradient, the proximate driver of the relationship, is poorly known. Here, using data on the distribution of birds in southern Africa, for which species richness increases linearly with energy availability, we provide an explicit determination of this structure. We show that most species exhibit increasing occupancy towards more productive regions (occurring in more grid cells within a productivity class). However, average reporting rates per species within occupied grid cells, a correlate of local density, do not show a similar increase. The mean range of used energy levels and the mean geographical range size of species in southern Africa decreases along the energy gradient, as most species are present at high productivity levels but only some can extend their ranges towards lower levels. Species turnover among grid cells consequently decreases towards high energy levels. In summary, these patterns support the hypothesis that higher productivity leads to more species by increasing the probability of occurrence of resources that enable the persistence of viable populations, without necessarily affecting local population densities
Trait anxiety, leadership and group-induced decision change
The twelve item Choice Dilemmas Questionnaire (CDQ) developed by Kogan and Wallach (1964) has been used extensively for investigating individual and group decision-making processes. Each item presents a hypothetical life situation in which the central character must choose between two courses of action, one of which is more risky than the other but also more rewarding if successful. For each situation the Sis must select the lowest probability of success they would accept before recommending that the potentially more rewarding (and risky) alternative be chosen. After Ss have made their private individual choices, a group is formed and each item is discussed until a consensus decision is reached. Following group discussion to consensus, Ss again make individual decisions in which they are allowed to change their decisions from that of the group if they so desire. When all twelve items are analyzed together, the typical finding is that the group consensus decision is more risky than the average of privately made individual pre-consensus decisions, and that the shift toward risk tends to be maintained for the average of privately made post-group Consensus decisions (Cartwright, 1971). Stoner (1961), the discoverer of the phenomenon, labled the effect the risky shift
Mapping biodiversity value worldwide: combining higher-taxon richness from different groups
Maps of large-scale biodiversity are urgently needed to guide conservation, and yet complete enumeration of organisms is impractical at present. One indirect approach is to measure richness at higher taxonomic ranks, such as families. The difficulty is how to combine information from different groups on numbers of higher taxa, when these taxa may in effect have been defined in different ways, particularly for more distantly related major groups. In this paper, the regional family richness of terrestrial and freshwater seed plants, amphibians, reptiles and mammals is mapped worldwide by combining: (i) absolute family richness; (ii) proportional family richness; and (iii) proportional family richness weighted for the total species richness in each major group. The assumptions of the three methods and their effects on the results are discussed, although for these data the broad pattern is surprisingly robust with respect to the method of combination. Scores from each of the methods of combining families are used to rank the top five richness hotspots and complementary areas, and hotspots of endemism are mapped by unweighted combination of range-size rarity scores
Focusing on the Big Picture: Insights into a Systems Approach to Deep Learning for Satellite Imagery
Deep learning tasks are often complicated and require a variety of components
working together efficiently to perform well. Due to the often large scale of
these tasks, there is a necessity to iterate quickly in order to attempt a
variety of methods and to find and fix bugs. While participating in IARPA's
Functional Map of the World challenge, we identified challenges along the
entire deep learning pipeline and found various solutions to these challenges.
In this paper, we present the performance, engineering, and deep learning
considerations with processing and modeling data, as well as underlying
infrastructure considerations that support large-scale deep learning tasks. We
also discuss insights and observations with regard to satellite imagery and
deep learning for image classification.Comment: Accepted to IEEE Big Data 201
An Examination of the African American Male Perception of Church Attendance
The variances among religious groups in the U.S. have been presumed to have weakened, yet class and ethnic variances have been largely overlooked by sociology (Wilde et. al., 2018, as cited in Pyle & Davidson, 2014). Though some research focuses explicitly on African American (AA) men, (Fitzgerald, 2010; Davis, 2020; Truss, 2018) the researcher discovered little evidence emphasizing AA men who are de-churched (Trends in the black church: More faithful, but not immune to decline, 2021; Dechurched: Witness & Outreach, 2021, para 1). The purpose of this qualitative, phenomenological study is to understand why AA males are increasingly becoming religiously unaffiliated and no longer see the relevance of attending church. The goal of this research is to cognize the basis for dwindling church presence among AA males to understand their declining attendance and avoidance of church and their conception of the relevance of attending church. The theory guiding this study is Robert K. Merton’s relative deprivation theory, which states that whether perceived or actual, is the deficiency of resources deemed essential to sustain a comparable quality of life (e.g. material, lifestyle, possessions) to what other socioeconomic groups or individuals with those groups are familiar (Longley, 2020)
How ecological communities respond to artificial light at night.
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Many ecosystems worldwide are exposed to artificial light at night (ALAN), from streetlights and other sources, and a wide range of organisms has been shown to respond to this anthropogenic pressure. This raises concerns about the consequences for major ecosystem functions and their stability. However, there is limited understanding of how whole ecological communities respond to ALAN, and this cannot be gained simply by making predictions from observed single species physiological, behavioral, or ecological responses. Research needs to include an important building block of ecological communities, namely the interactions between species that drive ecological and evolutionary processes in ecosystems. Here, we summarize current knowledge about community responses to ALAN and illustrate different pathways and their impact on ecosystem functioning and stability. We discuss that documentation of the impact of ALAN on species interaction networks and trait distributions provides useful tools to link changes in community structure to ecosystem functions. Finally, we suggest several approaches to advance research that will link the diverse impact of ALAN to changes in ecosystems.The research leading to this paper was funded from NERC grant NE/N001672/1
Causality in 3D Massive Gravity Theories
We study the constraints coming from local causality requirement in various
dimensional dynamical theories of gravity. In topologically massive
gravity, with a single parity non-invariant massive degree of freedom, and in
new massive gravity, with two massive spin- degrees of freedom, causality
and unitarity are compatible with each other and both require the Newton's
constant to be negative. In their extensions, such as the Born-Infeld gravity
and the minimal massive gravity the situation is similar and quite different
from their higher dimensional counterparts, such as quadratic (e.g.,
Einstein-Gauss-Bonnet) or cubic theories, where causality and unitarity are in
conflict. We study the problem both in asymptotically flat and asymptotically
anti-de Sitter spaces.Comment: This version has significant improvements: causality discussion of
all the well-known gravity theories in flat space is extended to the AdS
space, references added, 29 pages, latest version matches the published on
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