Body size, energetics, and the Ordovician restructuring of marine ecosystems

Paleobiology ◽  
2008 ◽  
Vol 34 (3) ◽  
pp. 342-359 ◽  
Author(s):  
Seth Finnegan ◽  
Mary L. Droser
Keyword(s):  
Body Size ◽  
Relative Abundance ◽  
Late Ordovician ◽  
Depositional Environments ◽  
Data Set ◽  
Widespread Occurrence ◽  
Trade Offs ◽  
Shallow Subtidal ◽  
Ecological Dominance ◽  
Benthic Ecosystems

Major shifts in ecological dominance are one of the most conspicuous but poorly understood features of the fossil record. Here we examine one of the most prominent such shifts, the Ordovician shift from trilobite to brachiopod dominance of benthic ecosystems. Using an integrated database of high-resolution paleoecological samples and body size data, we show that while the average local richness and relative abundance of trilobites declined significantly through the Ordovician, the estimated standing biomass of trilobites, and by implication the amount of energy that they used, remained relatively invariant. This is attributable to an increase in the average body size of trilobite species in our data set, and especially to the widespread occurrence of the exceptionally large Middle-Late Ordovician trilobite genus Isotelus. Brachiopods increase in both mean body size and relative abundance throughout the Ordovician, so that estimates of brachiopod biomass and energetic use increase substantially between the Early and Late Ordovician. Although the data set includes a range of depositional environments, similar trends are observed in both shallow subtidal and deep subtidal settings. These results suggest that diversification of the Paleozoic Fauna did not come at the energetic expense of the Cambrian Fauna. The declining relative abundance of trilobites may reflect a combination of numerical dilution and the necessary energetic trade-offs between body size and abundance.

scholarly journals Fundamental resource trade-offs for encoded distributed optimization

2020 ◽  
Author(s):  
A Salman Avestimehr ◽  
Seyed Mohammadreza Mousavi Kalan ◽  
Mahdi Soltanolkotabi
Keyword(s):  
Computational Time ◽  
Massive Data ◽  
Data Sets ◽  
Massive Data Sets ◽  
Computational Framework ◽  
Data Set ◽  
Trade Offs ◽  
Major Bottleneck ◽  
Computing Environments ◽  
Analyze Data

Abstract Dealing with the shear size and complexity of today’s massive data sets requires computational platforms that can analyze data in a parallelized and distributed fashion. A major bottleneck that arises in such modern distributed computing environments is that some of the worker nodes may run slow. These nodes a.k.a. stragglers can significantly slow down computation as the slowest node may dictate the overall computational time. A recent computational framework, called encoded optimization, creates redundancy in the data to mitigate the effect of stragglers. In this paper, we develop novel mathematical understanding for this framework demonstrating its effectiveness in much broader settings than was previously understood. We also analyze the convergence behavior of iterative encoded optimization algorithms, allowing us to characterize fundamental trade-offs between convergence rate, size of data set, accuracy, computational load (or data redundancy) and straggler toleration in this framework.

Demographic life history traits of reproductive natterjack toads (Bufo calamita) vary between northern and southern latitudes

2006 ◽  
Vol 27 (3) ◽  
pp. 365-375 ◽  
Author(s):  
Delfi Sanuy ◽  
Christoph Leskovar ◽  
Neus Oromi ◽  
Ulrich Sinsch
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Large Female ◽  
Breeding Period ◽  
Female Size ◽  
Data Set ◽  
Bufo Calamita ◽  
Trade Offs ◽  
Age Variation ◽  
The Cost

AbstractDemographic life history traits were investigated in three Bufo calamita populations in Germany (Rhineland-Palatinate: Urmitz, 50°N; 1998-2000) and Spain (Catalonia: Balaguer, Mas de Melons, 41°N; 2004). We used skeletochronology to estimate the age as number of lines of arrested growth in breeding adults collected during the spring breeding period (all localities) and during the summer breeding period (only Urmitz). A data set including the variables sex, age and size of 185 males and of 87 females was analyzed with respect to seven life history traits (age and size at maturity of the youngest first breeders, age variation in first breeders, longevity, potential reproductive lifespan, median lifespan, age-size relationship). Spring and summer cohorts at the German locality differed with respect to longevity and potential reproductive lifespan by one year in favour of the early breeders. The potential consequences on fitness and stability of cohorts are discussed. Latitudinal variation of life history traits was mainly limited to female natterjacks in which along a south-north gradient longevity and potential reproductive lifespan increased while size decreased. These results and a review of published information on natterjack demography suggest that lifetime number of offspring seem to be optimized by locally different trade-offs: large female size at the cost of longevity in southern populations and increased longevity at the cost of size in northern ones.

Allometry of home range size in lake and river fishes

1995 ◽  
Vol 52 (7) ◽  
pp. 1499-1508 ◽  
Author(s):  
Charles K. Minns
Keyword(s):  
Body Size ◽  
Home Range ◽  
Freshwater Fish ◽  
Fish Population ◽  
Home Range Size ◽  
Range Size ◽  
Territory Size ◽  
Home Ranges ◽  
Data Set ◽  
Terrestrial Mammals

A data set assembled from published literature supported the hypotheses that (i) home range size increases allometrically with body size in temperate freshwater fishes, and (ii) fish home ranges are larger in lakes than rivers. The allometric model fitted was home range = A∙(body size)B. Home ranges in lakes were 19–23 times larger than those in rivers. Additional analyses showed that membership in different taxonomic groupings of fish, the presence–absence of piscivory, the method of measuring home range, and the latitude position of the water bodies were not significant predictive factors. Home ranges of freshwater fish were smaller than those of terrestrial mammals, birds, and lizards. Home ranges were larger than area per fish values derived by inverting fish population and assemblage density–size relationships from lakes and rivers and territory–size relationships in stream salmonids. The weight exponent (B) of fish home range was lower than values reported for other vertebrates, 0.58 versus a range of 0.96–1.14. Lake–river home range differences were consistent with differences reported in allometric models of freshwater fish density and production.

scholarly journals Robust estimation of vertical symmetry axis models via joint migration inversion: Including multiples in anisotropic parameter estimation

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. C57-C74 ◽  
Author(s):  
Abdulrahman A. Alshuhail ◽  
Dirk J. Verschuur
Keyword(s):  
Symmetry Axis ◽  
Transverse Isotropy ◽  
Half Cycle ◽  
Anisotropic Parameter ◽  
Data Set ◽  
Trade Off ◽  
Trade Offs ◽  
Highly Nonlinear ◽  
Wide Range ◽  
Internal Multiples

Because the earth is predominately anisotropic, the anisotropy of the medium needs to be included in seismic imaging to avoid mispositioning of reflectors and unfocused images. Deriving accurate anisotropic velocities from the seismic reflection measurements is a highly nonlinear and ambiguous process. To mitigate the nonlinearity and trade-offs between parameters, we have included anisotropy in the so-called joint migration inversion (JMI) method, in which we limit ourselves to the case of transverse isotropy with a vertical symmetry axis. The JMI method is based on strictly separating the scattering effects in the data from the propagation effects. The scattering information is encoded in the reflectivity operators, whereas the phase information is encoded in the propagation operators. This strict separation enables the method to be more robust, in that it can appropriately handle a wide range of starting models, even when the differences in traveltimes are more than a half cycle away. The method also uses internal multiples in estimating reflectivities and anisotropic velocities. Including internal multiples in inversion not only reduces the crosstalk in the final image, but it can also reduce the trade-off between the anisotropic parameters because internal multiples usually have more of an imprint of the subsurface parameters compared with primaries. The inverse problem is parameterized in terms of a reflectivity, vertical velocity, horizontal velocity, and a fixed [Formula: see text] value. The method is demonstrated on several synthetic models and a marine data set from the North Sea. Our results indicate that using JMI for anisotropic inversion makes the inversion robust in terms of using highly erroneous initial models. Moreover, internal multiples can contain valuable information on the subsurface parameters, which can help to reduce the trade-off between anisotropic parameters in inversion.

scholarly journals WHATEVER YOU WANT: INCONSISTENT RESULTS IS THE RULE, NOT THE EXCEPTION, IN THE STUDY OF PRIMATE BRAIN EVOLUTION

2018 ◽  
Author(s):  
Andreas Wartel ◽  
Patrik Lindenfors ◽  
Johan Lind
Keyword(s):  
Body Size ◽  
Brain Evolution ◽  
Data Sets ◽  
Data Set ◽  
Scientific Rigor ◽  
Explanatory Variables ◽  
Primate Brain ◽  
Residual Variation ◽  
The Many ◽  
Brain Data

AbstractPrimate brains differ in size and architecture. Hypotheses to explain this variation are numerous and many tests have been carried out. However, after body size has been accounted for there is little left to explain. The proposed explanatory variables for the residual variation are many and covary, both with each other and with body size. Further, the data sets used in analyses have been small, especially in light of the many proposed predictors. Here we report the complete list of models that results from exhaustively combining six commonly used predictors of brain and neocortex size. This provides an overview of how the output from standard statistical analyses changes when the inclusion of different predictors is altered. By using both the most commonly tested brain data set and a new, larger data set, we show that the choice of included variables fundamentally changes the conclusions as to what drives primate brain evolution. Our analyses thus reveal why studies have had troubles replicating earlier results and instead have come to such different conclusions. Although our results are somewhat disheartening, they highlight the importance of scientific rigor when trying to answer difficult questions. It is our position that there is currently no empirical justification to highlight any particular hypotheses, of those adaptive hypotheses we have examined here, as the main determinant of primate brain evolution.

The Swift Fox in Rangeland and Cropland in Western Kansas: Relative Abundance, Mortality, and Body Size

2000 ◽  
Vol 45 (2) ◽  
pp. 221 ◽  
Author(s):  
Raymond S. Matlack ◽  
Philip S. Gipson ◽  
Donald W. Kaufman
Keyword(s):  
Body Size ◽  
Relative Abundance ◽  
Swift Fox

Design Trade-Offs Under Power Asymmetry: COPs and Flexibility Clauses

2021 ◽  
pp. 1-25
Author(s):  
Jean-Frédéric Morin ◽  
Benjamin Tremblay-Auger ◽  
Claire Peacock
Keyword(s):  
Design Feature ◽  
Original Data ◽  
Environmental Agreements ◽  
Data Set ◽  
Power Asymmetry ◽  
Trade Offs ◽  
Environmental Agreement ◽  
The Creation ◽  
Insurance Mechanism ◽  
Important Design

Abstract Negotiating parties to an environmental agreement can manage uncertainty by including flexibility clauses, such as escape and withdrawal clauses. This article investigates a type of uncertainty so far overlooked by the literature: the uncertainty generated by the creation of a Conference of the Parties (COP) in a context of sharp power asymmetry. When negotiating an agreement, it is difficult for powerful states to make a credible commitment to weaker states, whereby they will not abuse their power to influence future COP decision-making. Flexibility clauses provide a solution to this credibility issue. They act as an insurance mechanism in case a powerful state hijacks the COP. Thus we expect that the creation of a collective body interacts with the degree of power asymmetry to make flexibility clauses more likely in environmental agreements. To test this argument, we draw on an original data set of several specific clauses in 2,090 environmental agreements, signed between 1945 and 2018. The results support our hypothesis and suggest that flexibility clauses are an important design feature of adaptive environmental agreements.

SKT

2021 ◽  
Vol 14 (11) ◽  
pp. 2369-2382
Author(s):  
Monica Chiosa ◽  
Thomas B. Preußer ◽  
Gustavo Alonso
Keyword(s):  
Frequency Distribution ◽  
Empirical Evaluation ◽  
Large Data ◽  
Cloud Service ◽  
Data Sets ◽  
Data Set ◽  
Single Pass ◽  
Trade Offs ◽  
Significant Performance ◽  
Spatial Architecture

Data analysts often need to characterize a data stream as a first step to its further processing. Some of the initial insights to be gained include, e.g., the cardinality of the data set and its frequency distribution. Such information is typically extracted by using sketch algorithms, now widely employed to process very large data sets in manageable space and in a single pass over the data. Often, analysts need more than one parameter to characterize the stream. However, computing multiple sketches becomes expensive even when using high-end CPUs. Exploiting the increasing adoption of hardware accelerators, this paper proposes SKT , an FPGA-based accelerator that can compute several sketches along with basic statistics (average, max, min, etc.) in a single pass over the data. SKT has been designed to characterize a data set by calculating its cardinality, its second frequency moment, and its frequency distribution. The design processes data streams coming either from PCIe or TCP/IP, and it is built to fit emerging cloud service architectures, such as Microsoft's Catapult or Amazon's AQUA. The paper explores the trade-offs of designing sketch algorithms on a spatial architecture and how to combine several sketch algorithms into a single design. The empirical evaluation shows how SKT on an FPGA offers a significant performance gain over high-end, server-class CPUs.

scholarly journals The Political Economy of Bilateral Bailouts

2020 ◽  
Vol 74 (1) ◽  
pp. 1-29 ◽  
Author(s):  
Christina J. Schneider ◽  
Jennifer L. Tobin
Keyword(s):  
Political Economy ◽  
Financial Crises ◽  
Domestic Politics ◽  
Complex Structure ◽  
Spillover Effects ◽  
The Political ◽  
Central Component ◽  
Theoretical Argument ◽  
Data Set ◽  
Trade Offs

AbstractIMF loans during times of financial crisis often occur in conjunction with bilateral financial rescues. These bilateral bailouts are substantial in size and a central component of international cooperation during financial crises. We analyze the political economy of bilateral bailouts and study the trade-offs that potential creditor governments experience when other countries find themselves in financial distress. Creditor governments want to stabilize crisis countries by providing additional liquidity, particularly if the crisis country is economically or politically important to them, but they are constrained by domestic politics. Politicians aim to balance these countervailing pressures. They provide bailouts when their own economy is exposed to negative spillover effects and when the crisis country is important for geostrategic, military, or political reasons. Domestic economic and political constraints, on the other hand, limit their ability to bail out other countries. We test our hypotheses using an original data set on bilateral bailouts by the G7 countries to countries that experienced financial crises between 1975 and 2010. The findings of our statistical analysis support our theoretical argument and contribute to a deeper understanding of international cooperation's complex structure during financial crises.

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