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The fossil record of the terminal Ediacaran Period is typified by the iconic index fossil Cloudina and its relatives. These tube-dwellers are presumed to be primitive metazoans, but resolving their phylogenetic identity has remained a point of contention. The root of the problem is a lack of diagnostic features; that is, phylogenetic interpretations have largely centered on the only available source of information—their external tubes. Here, using tomographic analyses of fossils from the Wood Canyon Formation (Nevada, USA), we report evidence of recognizable soft tissues within their external tubes. Although alternative interpretations are plausible, these internal cylindrical structures may be most appropriately interpreted as digestive tracts, which would be, to date, the earliest-known occurrence of such features in the fossil record. If this interpretation is correct, their nature as one-way through-guts not only provides evidence for establishing these fossils as definitive bilaterians but also has implications for the long-debated phylogenetic position of the broader cloudinomorphs. Cloudinomorphs were one of the few groups to survive from the Ediacaran into the Cambrian, but they are known only from their external tubes. Here, Schiffbauer et al. report soft-tissue preservation of cloudinomorphs; the internal structures are interpreted as guts characteristic of bilaterians.

The Ediacaran to Cambrian Deep Spring Formation consists of mixed carbonate-siliciclastic strata which contain an increasingly complex and biogeographically important biota. Past investigations of the Deep Spring Formation at Mt. Dunfee, Nevada, explored the highly diverse microbialite reefs consisting of a wide range of stromatolite morphologies which exerted significant control on local sedimentation and topography. Early investigations also documented the biomineralizing metazoan Cloudina (an Ediacaran index fossil). However, recent exploration of the area has resulted in the discovery of several new metazoan fossil communities consisting of a diverse assemblage of Ediacaran soft-tissue tubicolous vermiforms (tube fossils) similar to Cloudina. The focus of this dissertation is on the geomicrobiological processes at work in the Deep Spring Formation and elsewhere which result in the preservation of soft-tissues (Ch. 2), the dissolution/precipitation of feldspars within stromatolites (Ch. 3), and the early formation of modern desert varnish (Ch. 4). Chapter 1 of my dissertation examines the stratigraphic and paleontologic context of the Deep Spring Formation. In this chapter, I summarize the current understanding of the paleontological transition at the Ediacaran-Cambrian boundary in the western United States. The Death Valley and White-Inyo-Esmeralda regions of California and Nevada contain some of the most fossiliferous terminal Neoproterozoic to early Phanerozoic strata in the world. Within these strata, the Cambrian explosion is in full display, resplendent with diverse trace and body fossils. The Wood Canyon and Deep Spring Formations, within which the boundary is contained, are comprised of mixed carbonate and siliciclastic lithologies—allowing for a more in-depth understanding of this critical transition in the history of life. Here, I briefly review our current state of understanding of life contained within these rocks. This chapter has been published (Strange and Rowland, 2017)Chapter 2 consists of a manuscript I submitted to the journal Geobiology describing the microbial-related mineralization pathways responsible for preserving the upper fossil horizon in the Deep Spring Formation at Mt. Dunfee, Nevada. The manuscript was recently rejected, with an offer to resubmit after reviewers’ comments have been addressed. In this manuscript, I describe a new mineralization pathway to exceptional fossil preservation which involves the metabolic activities of an iron-oxidizing bacterial community. This model expands on previous microbial/redox zonation models of exceptional preservation and requires rapid emplacement of organic matter into the microaerophilic sedimentary environment. Within these redox conditions, iron-oxidation by bacteria produce abundant Fe (III) from porewater sourced Fe (II), resulting in the precipitation of early Fe (III) mineral phases with the quick stabilization in the form of goethite and iron-rich aluminosilicates. I have named this taphonomic pathway “ferrumation”. Ferrumation incorporates well into the microbial/redox zonation model of Schiffbauer et al. (2014) due to the occurrence of pyritization within the fossil assemblage.Chapter 3 moves away from iron-oxidizing bacteria to the mineral producing capabilities of the consortia of microbes involved in stromatolite formation. Feldspar assemblages found within stromatolite laminae differ between stromatolite localities and from the surrounding interstromatolite zone between columnar stromatolites. This suggests that microbial activities may be influencing their dissolution and precipitation. Textural associations between feldspars, quartz, and calcite are similar to the micrographic textures seen in some igneous rocks which result from the co-stability of feldspar and quartz in a magma chamber. These highly unusual feldspar textures within Deep Spring stromatolites led to the hypothesis that microbial activity resulted in the dissolution of detrital feldspars (mostly orthoclase) captured by the sticky surface of the stromatolite. The capture of dissolved ions from detrital orthoclase by organic molecules become released into the closed system of a mineralizing microbialite and precipitate out as authigenic albite, quartz, Ca-plagioclase, and a K-rich aluminosilicate, or their poorly crystalline precursors. This pattern of feldspar-quartz-calcite associations has been found at the Ediacaran-Cambrian Mount Dunfee section and the Molly Gibson Mine section of the Deep Spring Formation, in Miocene stromatolites from the Duero Basin, Spain, and also in a stromatolite from the Flinders Range, Australia. This research is significant because it could lead to the ability to isolate and date authigenic albite grains using the Ar/Ar method, potentially opening the utilization of stromatolites as abundant repositories of syndepositional authigenic minerals for geochronology.Chapter four departs from the Ediacaran-Cambrian boundary but continues with the theme of microbe-mineral interactions. This chapter details the earliest phases of desert varnish formation on ephemeral wash sediments from Nelson, Nevada. I show that the early development of incipient desert varnish occurs through small “microdots”. These are likely associated with Fe- and Mn-oxidizing microbial communities on the surface of the sediment grains. The Fe-oxide composition of some microdots and the mixed-composition of more advanced desert varnish suggests that desert varnish may accumulate through the cyclic deposition of layers during periods of habitability of each microbial community. Desert varnish microdots are shown to have progressive mineralization from smooth surfaces to micronodules, while advanced development becomes botryoidal. The previously reported “microstromatolitic” growth habit of some desert varnish seems to correspond with the microdot morphology of the incipient varnish found on these grains.

This article introduces a new dataset of official financing from China to 138 developing countries between 2000 and 2014. It investigates whether Chinese development finance affects economic growth in recipient countries. The results demonstrate that Chinese development finance boosts short-term economic growth. An additional project increases growth by between 0.41 and 1.49 percentage points 2 years after commitment, on average. While this study does not find that significant financial support from China impairs the overall effectiveness of aid from Western donors, aid from the United States tends to be more effective in countries that receive no substantial support from China.

Abstract Chinese “aid” is a lightning rod for criticism. Policy-makers, journalists, and public intellectuals claim that Beijing uses its largesse to cement alliances with political leaders, secure access to natural resources, and create exclusive commercial opportunities for Chinese firms—all at the expense of citizens living in developing countries. We argue that much of the controversy about Chinese “aid” stems from a failure to distinguish between China's Official Development Assistance (ODA) and more commercially oriented sources and types of state financing. Using a new database on China's official financing commitments to Africa from 2000 to 2013, we find that the allocation of Chinese ODA is driven primarily by foreign policy considerations, while economic interests better explain the distribution of less concessional flows. These results highlight the need for better measures of an increasingly diverse set of non-Western financial activities.

China's provision of development finance to other countries is sizable but reliable information is scarce. We introduce a new open-source methodology for collecting project-level development finance information and create a database of Chinese official finance (OF) to Africa from 2000 to 2011. We find that China's commitments amounted to approximately US$73 billion, of which US$15 billion are comparable to Official Development Assistance following Organization for Economic Cooperation and Development definitions. We provide details on 1,511 projects to fifty African countries. We use this database to extend previous research on aid and conflict, which suffers from omitted-variable bias due to the exclusion of Chinese development finance. Our results show that sudden withdrawals of \"traditional\" aid no longer induce conflict in the presence of sufficient alternative funding from China. Our findings highlight the importance of gathering more complete data on the development activities of \"nontraditional donors\" to better understand the link between aid and conflict.

The term ‘artificial intelligence’ has arguably come to function in political discourse as, what Laclau called, an ‘empty signifier’. This article traces the shifting political discourse on AI within three key institutions of global governance–OHCHR, WHO, and UNESCO–and, in so doing, highlights the role of ‘crisis’ moments in justifying a series of pivotal re-articulations. Most important has been the attachment of AI to the narrative around digital automation in human healthcare. Greatly enabled by the societal context of the pandemic, all three institutions have moved from being critical of the unequal power relations in the economy of AI to, today, reframing themselves primarily as facilitators tasked with helping to ensure the application of AI technologies. The analysis identifies a shift in which human health and healthcare is framed as in a ‘crisis’ to which AI technology is presented as the remedy. The article argues the need to trace these discursive shifts as a means by which to understand, monitor, and where necessary also hold to account these changes in the governance of AI in society.

Often phrased in terms of “societal relevance” and “societal impact,” academic researchers are increasingly expected to design projects that engage with the public and policymakers both through communicating research outputs as well as inclusion within data collection and processing. This article reports on one such engagement initiative that was, paradoxically, a response to the state of mass social isolation imposed on many in the context of the 2020 pandemic. What became known as the “PHED Commission on the Future of Health Post-COVID 19” created a virtual environment that stretched across academic and professional fields, inviting a broad range of actors to provide evidence that was archived (i.e., videoed) and published online and later turned into a written report. In discussing the “Commission,” the article highlights the lessons learned during the process, including the tensions and solutions by which to help contribute to public debates and have societal impact. While we hope that the pandemic remains an exception, we argue that it is important to see where we can benefit from the innovations developed in that moment of crisis while not ignoring the strengths of traditional research practices. Such transdisciplinary activities are, the article argues, important to knowledge that can help advance health and equity.

Cytochrome bc1 is a proven drug target in the prevention and treatment of malaria. The rise in drug-resistant strains of Plasmodium falciparum, the organism responsible for malaria, has generated a global effort in designing new classes of drugs. Much of the design/redesign work on overcoming this resistance has been focused on compounds that are presumed to bind the Q(o) site (one of two potential binding sites within cytochrome bc1 using the known crystal structure of this large membrane-bound macromolecular complex via in silico modeling. Cocrystallization of the cytochrome bc1 complex with the 4(1H)-pyridone class of inhibitors, GSK932121 and GW844520, that have been shown to be potent antimalarial agents in vivo, revealed that these inhibitors do not bind at the Q(o) site but bind at the Q(i )site. The discovery that these compounds bind at the Q(i) site may provide a molecular explanation for the cardiotoxicity and eventual failure of GSK932121 in phase-1 clinical trial and highlight the need for direct experimental observation of a compound bound to a target site before chemical optimization and development for clinical trials. The binding of the 4(1H)-pyridone class of inhibitors to Q(i) also explains the ability of this class to overcome parasite Q(o)-based atovaquone resistance and provides critical structural information for future design of new selective compounds with improved safety profiles.

Periprosthetic joint infection (PJI) is a serious complication of total knee arthroplasty. Two-stage revision is the most widely used technique and considered as the most effective for treating periprosthetic knee infection. The one-stage revision strategy is an emerging alternative option, however, its performance in comparison to the two-stage strategy is unclear. We therefore sought to ask if there was a difference in re-infection rates and other clinical outcomes when comparing the one-stage to the two-stage revision strategy. Our first objective was to compare re-infection (new and recurrent infections) rates for one- and two-stage revision surgery for periprosthetic knee infection. Our second objective was to compare between the two revision strategies, clinical outcomes as measured by postoperative Knee Society Knee score, Knee Society Function score, Hospital for Special Surgery knee score, WOMAC score, and range of motion. Systematic review and meta-analysis. MEDLINE, EMBASE, Web of Science, Cochrane Library, reference lists of relevant studies to August 2015, and correspondence with investigators. Longitudinal (prospective or retrospective cohort) studies conducted in generally unselected patients with periprosthetic knee infection treated exclusively by one- or two-stage revision and with re-infection outcomes reported within two years of revision surgery. No clinical trials comparing both revision strategies were identified. Two independent investigators extracted data and discrepancies were resolved by consensus with a third investigator. Re-infection rates from 10 one-stage studies (423 participants) and 108 two-stage studies (5,129 participants) were meta-analysed using random-effect models after arcsine transformation. The rate (95% confidence intervals) of re-infection was 7.6% (3.4-13.1) in one-stage studies. The corresponding re-infection rate for two-stage revision was 8.8% (7.2-10.6). In subgroup analyses, re-infection rates remained generally similar for several study-level and clinically relevant characteristics. Postoperative clinical outcomes of knee scores and range of motion were similar for both revision strategies. Potential bias owing to the limited number of one-stage revision studies and inability to explore heterogeneity in greater detail. Available evidence from aggregate published data suggest the one-stage revision strategy may be as effective as the two-stage revision strategy in treating infected knee prostheses in generally unselected patients. Further investigation is warranted. PROSPERO 2015: CRD42015017327.

Global temperature changes have emphasized the need to understand how species adapt to thermal stress across their ranges. Genetic mechanisms may contribute to variation in thermal tolerance, providing evidence for how organisms adapt to local environments. We determine physiological thermal limits and characterize genome-wide transcriptional changes at these limits in bumble bees using laboratory-reared Bombus vosnesenskii workers. We analyze bees reared from latitudinal (35.7–45.7°N) and altitudinal (7–2154 m) extremes of the species’ range to correlate thermal tolerance and gene expression among populations from different climates. We find that critical thermal minima (CT MIN ) exhibit strong associations with local minimums at the location of queen origin, while critical thermal maximum (CT MAX ) was invariant among populations. Concordant patterns are apparent in gene expression data, with regional differentiation following cold exposure, and expression shifts invariant among populations under high temperatures. Furthermore, we identify several modules of co-expressed genes that tightly correlate with critical thermal limits and temperature at the region of origin. Our results reveal that local adaptation in thermal limits and gene expression may facilitate cold tolerance across a species range, whereas high temperature responses are likely constrained, both of which may have implications for climate change responses of bumble bees.