Reproductive innovations and pulsed rise in plant complexity

Morphological complexity is a notable feature of multicellular life, although whether it evolves gradually or in early bursts is unclear. Vascular plant reproductive structures, such as flowers, are familiar examples of complex morphology. In this study, we use a simple approach based on the number of part types to analyze changes in complexity over time. We find that reproductive complexity increased in two pulses separated by ~250 million years of stasis, including an initial rise in the Devonian with the radiation of vascular plants and a pronounced increase in the Late Cretaceous that reflects flowering plant diversification. These pulses are associated with innovations that increased functional diversity, suggesting that shifts in complexity are linked to changes in function regardless of whether they occur early or late in the history of vascular plants

A topical approach to retrievability bias estimation

Retrievability is an independent evaluation measure that offers insights to an aspect of retrieval systems that performance and efficiency measures do not. Retrievability is often used to calculate the retrievability bias, an indication of how accessible a system makes all the documents in a collection. Generally, computing the retrievability bias of a system requires a colossal number of queries to be issued for the system to gain an accurate estimate of the bias. However, it is often the case that the accuracy of the estimate is not of importance, but the relationship between the estimate of bias and performance when tuning a systems parameters. As such, reaching a stable estimation of bias for the system is more important than getting very accurate retrievability scores for individual documents. This work explores the idea of using topical subsets of the collection for query generation and bias estimation to form a local estimate of bias which correlates with the global estimate of retrievability bias. By using topical subsets, it would be possible to reduce the volume of queries required to reach an accurate estimate of retrievability bias, reducing the time and resources required to perform a retrievability analysis. Findings suggest that this is a viable approach to estimating retrievability bias and that the number of queries required can be reduced to less than a quarter of what was previously thought necessary

Hemisphere-scale differences in conifer evolutionary dynamics

Fundamental differences in the distribution of oceans and landmasses in the Northern and Southern Hemispheres potentially impact patterns of biological diversity in the two areas. The evolutionary history of conifers provides an opportunity to explore these dynamics, because the majority of extant conifer species belong to lineages that have been broadly confined to the Northern or Southern Hemisphere during the Cenozoic. Incorporating genetic information with a critical review of fossil evidence, we developed an age-calibrated phylogeny sampling ∼80% of living conifer species. Most extant conifer species diverged recently during the Neogene within clades that generally were established during the later Mesozoic, but lineages that diversified mainly in the Southern Hemisphere show a significantly older distribution of divergence ages than their counterparts in the Northern Hemisphere. Our tree topology and divergence times also are best fit by diversification models in which Northern Hemisphere conifer lineages have higher rates of species turnover than Southern Hemisphere lineages. The abundance of recent divergences in northern clades may reflect complex patterns of migration and range shifts during climatic cycles over the later Neogene leading to elevated rates of speciation and extinction, whereas the scattered persistence of mild, wetter habitats in the Southern Hemisphere may have favored the survival of older lineages

Applying psychological type theory to cathedral visitors : a case study of two cathedrals in England and Wales

This study employs Jungian psychological type theory to profile visitors to Chester Cathedral in England and St Davids Cathedral in Wales. Psychological type theory offers a fourfold psychographic segmentation of visitors, distinguishing between introversion and extraversion, sensing and intuition, thinking and feeling, and judging and perceiving. New data provided by 157 visitors to Chester Cathedral (considered alongside previously published data provided by 381 visitors to St Davids Cathedral) demonstrated that these two cathedrals attract more introverts than extraverts, more sensers than intuitives, and more judgers than perceivers, but equal proportions of thinkers and feelers. Comparison with the population norms demonstrated that extraverts and perceivers are significantly under-represented among visitors to these two cathedrals. The implications of these findings are discussed both for maximising the visitor experiences of those already attracted to these cathedrals and for discovering ways of attracting more extraverts and more perceivers to explore these cathedrals

Tuning of Peroxiredoxin Catalysis for Various Physiological Roles

Peroxiredoxins (Prxs) make up an ancient family of enzymes that are the predominant peroxidases for nearly all organisms and play essential roles in reducing hydrogen peroxide, organic hydroperoxides, and peroxynitrite. Even between distantly related organisms, the core protein fold and key catalytic residues related to its cysteine-based catalytic mechanism have been retained. Given that these enzymes appeared early in biology, Prxs have experienced over a billion years of optimization for specific ecological niches. Although their basic enzymatic function remains the same, Prxs have diversified and are involved in roles such as protecting DNA against mutation, defending pathogens against host immune responses, suppressing tumor formation, and—for eukaryotes—helping regulate peroxide signaling via hyperoxidation of their catalytic Cys. Here, we review the current understanding of the physiological roles of Prxs by analyzing knockout and knockdown studies from ca. twenty-five different species. We also review what is known about the structural basis for the sensitivity of some eukaryotic Prxs to inactivation by hyperoxidation. In considering the physiological relevance of hyperoxidation, we explore the distribution across species of sulfiredoxin (Srx), the enzyme responsible for rescuing hyperoxidized Prxs. We unexpectedly find that among eukaryotes appearing to have a “sensitive” Prx isoform, some do not contain Srx. Also, as Prxs are suggested to be promising targets for drug design, we discuss the rationale behind recently proposed strategies for their selective inhibition

First-year compliance with the Nevada Clean Indoor Air Act

Objectives: We quantitatively evaluated compliance with the Nevada Clean Indoor Air Act (NCIAA) by different types of businesses in Nevada and determined whether compliance affected indoor concentrations of benzene and 3-ethenyl pyridine (3-EP), markers of tobacco smoke. Methods: Managers of 181 businesses in Washoe County, Nevada, were interviewed about business characteristics and practices and policies related to smoking. During unannounced visits, compliance data and air samples (n=66) were collected from interviewed businesses and from an additional sample (n = 56) of businesses without knowledge of the study. Results: Overall compliance, as defined by the NCIAA, was low (28.2%). Benzene concentrations were higher in casino restaurants than in other businesses, although most complied with the requirements of the ban. Neither benzene nor 3-EP concentrations differed significantly between compliant and non-compliant businesses. Conclusions: The finding that casino restaurants had poorer air quality despite their compliance with the NCIAA suggests that compliance alone may not be sufficient to reduce exposure to secondhand smoke, particularly in buildings with both nonsmoking and smoking areas