Following the end-Permian mass extinction, temperatures remained elevated for similar to 5 Myr, suggesting a fundamental restructuring of the Earth's climate system. Both a weak silicate weathering feedback and CO2 release from enhanced marine authigenic clay precipitation are proposed to have sustained elevated temperatures during the Early Triassic. The lithium isotope (delta Li-7) proxy can reveal the roles of terrestrial and marine reverse weathering in maintaining elevated Early Triassic temperatures. We present the first delta Li-7 values from Upper Permian to Middle Triassic carbonate strata from the Panthalassa Ocean and the western Tethys Ocean. At the Permian/Triassic boundary, carbonate delta Li-7 values in these records, along with previously published data from the eastern Tethys, are consistently below 0 parts per thousand, and remain low in the Early Triassic. Differences in carbonate delta Li-7 values among sections are interpreted as the combined influence of diagenetic alteration and carbonate mineralogy on the isotopic fractionation from co-eval seawater. In the Early Triassic, we observe a large difference between carbonate delta Li-7 values and published siliciclastic records following the extinction. Even after accounting for carbonate diagenesis, these paired records imply Li isotope fractionation between carbonate minerals, authigenic marine clay, and seawater that are distinct from modern marine environments. Inferred minimum and maximum constraints on seawater delta Li-7 values from these Early Triassic records are also incompatible. We hypothesize that a reduced oceanic Li reservoir-and thus, short residence time-may account for the anomalous Early Triassic delta Li-7 records, implying a simultaneous increase in continental weathering and marine clay authigenesis. Heterogeneous seawater delta Li-7 records in the Early Triassic could be, therefore, a potential symptom of perturbed carbon-silica cycling that permitted elevated temperatures to persist far longer than the typical timescale for the silicate weathering feedback on Earth's climate.
African children's language learning is understudied. In two studies, we examine children's noun learning in Luganda, a dominant Bantu language in Uganda. In Study 1, the MacArthur-Bates CDI: Words and Sentences vocabulary checklist was adapted for Luganda. Parents of children aged 17-33 months (n = 27; Mage = 25.4 months; 16 female) were interviewed about their child's comprehension/production of each word. Children with smaller vocabularies showed a "noun bias" in production but favored verbs in comprehension. Children with larger vocabularies favored nouns in comprehension but showed no differences between nouns and verbs in comprehension or production when total nouns/verbs on the list are considered. Study 2 tested children's understanding of two common Luganda noun prefixes (omu- and eki-), asking whether children have linked these prefixes with cognitive categories (e.g. people, artifacts). In an experimental task, children aged 2-4 years (n = 24; M = 3 years; 16 girls) were asked to point to toy objects testing their knowledge of familiar omu- and eki- prefixed nouns and extension of these prefixes to novel nouns. Results showed that younger children could extend the prefix omu- (people, food) to new examples; the eki- prefix (artifacts, despised animals) was extended only by 4-year-olds. Comparing these results to checklist data, interestingly, children knew more nouns for artifacts than animates. Studies of children's acquisition of African languages, especially using experimental methods, are needed. We show evidence for a noun bias in Luganda is mixed and that children can attend to important prefix-cognitive category links - important results for the field.
Evolutionary entropy measures the temporal organization of reproductive contributions along the life cycle of an age-structured population. We develop a mathematical and empirical framework showing that, in iteroparous animal populations represented by Leslie-type demographic matrices, reproductive windows are frequently organized near the age classes selected by entropy maximization. Evolutionary entropy complements the classical net reproductive number and asymptotic growth rate: whereas these measure lifetime replacement and growth, entropy measures the temporal dispersion of the growth-adjusted reproductive distribution. Our central result is a reduction principle: under Euler–Lotka normalization, evolutionary entropy and generation time are invariant under multiplicative rescaling of survivorship and fertility on the reproductive interval. The relevant entropy is determined not by absolute survivorship, fertility, or juvenile mortality, but by the normalized post-maturity reproductive distribution. We derive explicit entropy functionals for finite and open-group Leslie models, including geometric reproductive tails. For the geometric regime, governed by we prove a sharp critical threshold separating populations with a unique finite entropy-maximizing endpoint from those whose entropy increases toward an asymptotic value in terms solely of the age at first reproduction. The theory is tested on 130 animal species. Entropy-derived predictions, computed from the demographic matrices alone, are compared with independent life-history variables. Predicted and observed reproductive medians coincide exactly for a majority of species, over 90
This article explains how David Bordwell's theory of classical Hollywood cinema changed over the years, comparing his writings from 1985 with later publications such as Reinventing Hollywood. While Bordwell continued to argue that narrative was a dominant principle in classical cinema, his definition of narrative grew more expansive, placing less emphasis on the causal chain and more emphasis on narrative dynamics. Extending this insight about classical narration to the study of classical style, I argue that stylistic devices, such as cinematography, do much more than causal clarification. Even in a storytelling context, a classical film may use cinematographyto hint, conceal, mislead, and reveal. Classical style can be eye-catching and emotionally charged, not in spite of narrative, and not in addition to narrative, but because of it.
