1,922 research outputs found
Evolutionary game dynamics of controlled and automatic decision-making
We integrate dual-process theories of human cognition with evolutionary game
theory to study the evolution of automatic and controlled decision-making
processes. We introduce a model where agents who make decisions using either
automatic or controlled processing compete with each other for survival. Agents
using automatic processing act quickly and so are more likely to acquire
resources, but agents using controlled processing are better planners and so
make more effective use of the resources they have. Using the replicator
equation, we characterize the conditions under which automatic or controlled
agents dominate, when coexistence is possible, and when bistability occurs. We
then extend the replicator equation to consider feedback between the state of
the population and the environment. Under conditions where having a greater
proportion of controlled agents either enriches the environment or enhances the
competitive advantage of automatic agents, we find that limit cycles can occur,
leading to persistent oscillations in the population dynamics. Critically,
however, these limit cycles only emerge when feedback occurs on a sufficiently
long time scale. Our results shed light on the connection between evolution and
human cognition, and demonstrate necessary conditions for the rise and fall of
rationality.Comment: 9 pages, 7 figure
Vision in the Hyperiid Amphipod Scina crassicornis
Light microscopy and extracellular electrophysiology were used to investigate eye structure and visual physiology of the hyperiid amphipod Scina crassicornis, a mesopelagic species that emits unusually short-wavelength luminescence (λmax=435-444 nm). The overall eye morphology is most similar to some previously described deep-dwelling amphipods, though not other hyperiids. Electroretinograms suggest that S. crassicornis possesses a relatively sensitive eye with slow temporal dynamics, and a monochromatic visual system (λmax=472 nm). Vision in S. crassicornis is well-suited for life in mesopelagic waters, and its short-wavelength luminescence does not play a role in intraspecific sexual signalling
Visual Physiology of the Antarctic Amphipod Abyssorchomene plebs
Although the visual systems of animals living in the cold, dark water of the deep sea have been investigated for some time, little is known about vision in animals inhabiting polar oceans, where temperatures are even colder and irradiance fluctuates dramatically with ice cover and season. Physiology of the compound eye of the amphipod Abyssorchomene plebs (Gammaridea: Lysianassoidea), a common Antarctic benthic scavenger, was studied electrophysiologically by electroretinography. A. plebs has a monochromatic visual system with a spectral sensitivity maximum at 487 nm, and higher sensitivity at ultraviolet wavelengths than predicted by a visual pigment template. While irradiance sensitivity determined from V/log I curves is comparable to that of mesopelagic crustaceans, temporal resolution calculated from response waveform dynamics and as determined by critical flicker fusion frequency suggest that the A. plebs eye is slower than that of crustaceans from the deep sea. A. plebs photoreceptors are physiologically adapted for a slow lifestyle in a low-light environment, where maximizing photon capture occurs at the expense of detecting fast events in the visual scene
Categorification of persistent homology
We redevelop persistent homology (topological persistence) from a categorical
point of view. The main objects of study are diagrams, indexed by the poset of
real numbers, in some target category. The set of such diagrams has an
interleaving distance, which we show generalizes the previously-studied
bottleneck distance. To illustrate the utility of this approach, we greatly
generalize previous stability results for persistence, extended persistence,
and kernel, image and cokernel persistence. We give a natural construction of a
category of interleavings of these diagrams, and show that if the target
category is abelian, so is this category of interleavings.Comment: 27 pages, v3: minor changes, to appear in Discrete & Computational
Geometr
Environmental Correlates of Nesting Success in Red-Shouldered Hawks
We evaluated the influence of weather on reproduction of the Red-shouldered Hawk (Buteo lineatus) in an agricultural landscape in south-central Florida where we found relatively high densities of successfully nesting hawks. We used a generalized linear modeling approach within an information-theoretic framework to examine the influence of total rainfall, rainfall frequency, and temperature on the timing of nesting, nesting success, and productivity of hawks during 1995-2000. The best models indicated an influence of rainfall frequency and laying period on hawk reproduction. During years with less frequent rainfall in the summer and fall months prior to the beginning of the breeding season, fewer pairs attempted to nest, and hawks nested later and had smaller clutch sizes and lower productivity. Hawks that nested later in the breeding season had lower hatching success and lower overall nest success. Although Red-shouldered Hawks are generally reported to inhabit forested landscapes throughout their range, a common feature seems to be a dependence on wetlands and riparian habitat for foraging. We propose that the proportion of wetlands throughout the landscape is a unique aspect of south-central Florida that may allow for persistence of unusually high numbers of hawks
Loss of buoyancy control in the copepod Calanus finmarchicus
A mechanism is demonstrated that could explain large-scale aggregations of lipid-rich copepods in the surface waters of marine environments. Laboratory experiments establish that changes in salinity and temperature induce lipid-mediated buoyancy instability that entrains copepods in surface waters. Reduced hydrostatic pressure associated with forced ascent of copepods at fjordic sills, shelf breaks and seamounts would also reduce the density of the lipid reserves, forcing copepods and particularly those in diapause to the surface. We propose that salinity, temperature and hydrodynamics of the physical environment, in conjunction with the biophysical properties of lipids, explain periodic high abundances of lipid-rich copepods in surface waters
Bolometric luminosities and infrared properties of carbon stars in the Magellanic Clouds and the Galaxy
Broad band J, H, K photometry and narrow band CO and H_2O indices have been obtained for 89 luminous red stars in the Large Magellanic Cloud (LMC) and 21 in the Small Magellanic Cloud (SMC), chosen largely from the sample of Blanco, McCarthy, and Blanco. Most are known to be carbon stars, and their infrared properties are compared with new observations of 33 galactic carbon stars. The bolometric luminosity distributions of an unbiased sample of Magellanic Cloud carbon stars are compared with those predicted from evolutionary calculations by Renzini and Voli for double shell burning stars undergoing He shell flashes. The observed and theoretical distributions disagree markedly: nearly all the observed stars have lower luminosities than even the faintest
theoretical carbon star.
In addition, we find many fewer than expected high luminosity stars with initial mass greater than 3 M_⊙. Possible explanations for this include a steep initial mass function for intermediate mass stars, a star formation rate significantly higher in the past than at present, or a neglected physical effect, such as underestimation of the importance of mass loss. Nevertheless, it appears that the hypothesis that He shell flashes lead to a dredge-up of carbon into the envelope, which results in a carbon star, can be maintained, if dredging occurs after fewer shell flashes than are predicted by presently available stellar evolutionary calculations.
The colors and indices of the late M giants in the LMC field are similar to those of late M giants in the Galaxy.
The narrow band infrared data are interpreted qualitatively in terms of the effects of molecular band absorption, which also strongly influences the infrared broad band colors of carbon stars. The small differences in the color-color relationships of the SMC and LMC samples are consistent with the differences in heavy metal abundance between the LMC, SMC, and Galaxy
Environmental Correlates of Breeding in the Crested Caracara (Caracara cheriway)
We evaluated the influence of weather on reproduction of the Crested Caracara (Caracara cheriway) in an agricultural landscape in south-central Florida. We used a mixed logistic-regression modeling approach within an information-theoretic framework to examine the influence of total rainfall, rainfall frequency, and temperature on the number of breeding pairs, timing of breeding, nest success, and productivity of Crested Caracaras during 1994–2000. The best models indicated an influence of rainfall frequency and laying period on reproduction. More individuals nested and more pairs nested earlier during years with more frequent rainfall in late summer and early fall. Pairs that nested later in each breeding season had smaller clutches, lower nest success and productivity, and higher probability of nest failure. More frequent rainfall during early spring months that are usually characterized by water deficit (March–May), more frequent rainfall during the fall drawdown period (September–November), and a shorter winter dry period showed some association with higher probability of brood reduction and lower nest success. The proportion of nests that failed was higher in wet years, when total rainfall during the breeding season (September–April) was \u3e10% above the 20-year average. Rainfall may influence reproduction in Crested Caracaras indirectly through food resources. As total rainfall increased during February–April, when most pairs are feeding nestlings or dependent fledglings, the proportion of drawdown-dependent species (those that become available as rainfall decreases and wetlands become isolated and shallow) in the diet of Crested Caracaras declined, which may indicate reduced availability of foraging habitat for this primarily terrestrial raptor
Beyond Contrastive Learning: A Variational Generative Model for Multilingual Retrieval
Contrastive learning has been successfully used for retrieval of semantically
aligned sentences, but it often requires large batch sizes or careful
engineering to work well. In this paper, we instead propose a generative model
for learning multilingual text embeddings which can be used to retrieve or
score sentence pairs. Our model operates on parallel data in languages and,
through an approximation we introduce, efficiently encourages source separation
in this multilingual setting, separating semantic information that is shared
between translations from stylistic or language-specific variation. We show
careful large-scale comparisons between contrastive and generation-based
approaches for learning multilingual text embeddings, a comparison that has not
been done to the best of our knowledge despite the popularity of these
approaches. We evaluate this method on a suite of tasks including semantic
similarity, bitext mining, and cross-lingual question retrieval -- the last of
which we introduce in this paper. Overall, our Variational Multilingual
Source-Separation Transformer (VMSST) model outperforms both a strong
contrastive and generative baseline on these tasks.Comment: Published as a long paper at ACL 202
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