Long-term memory of subduction processes in the lithospheric mantle: evidence from the geochemistry of basic dykes in the Gardar Province of South Greenland

The rift-related magmas of the Proterozoic Gardar Igneous Province were emplaced across the contact between the South Greenland Archaean craton and the Palaeoproterozoic Ketilidian mobile belt. It has been suggested that the geochemistry of Gardar intrusive rocks in the two areas varies across the craton margin and that this reflects a lithospheric control. However, comparison of the geochemical and isotopic signatures of basic and ultrabasic dykes from across the area shows that there is no systematic variation related to the age of the country rock. All the Gardar basic rocks are inferred to have been derived from the mantle, with relatively little crustal contamination. We suggest that the lithospheric mantle beneath the Gardar Province was enriched by slab-derived fluids during the Ketilidian orogeny (c. 1800 Ma). Subsequent melting of this mantle source was promoted during Gardar rifting when volatile-rich, small-degree melts from the asthenosphere were introduced into the lithospheric mantle, forming enriched metasomites. Ultrabasic lamprophyre dykes in the Gardar Province represent melts derived largely from these metasomites, whereas basaltic magmas were formed by larger-scale melting of the lithospheric mantle, inheriting a subductionrelated signature. There is no evidence that the Gardar magmas were derived from a highly enriched lithospheric keel that had existed since craton formation

Phase diagram of an Ising model with long-range frustrating interactions: a theoretical analysis

We present a theoretical study of the phase diagram of a frustrated Ising model with nearest-neighbor ferromagnetic interactions and long-range (Coulombic) antiferromagnetic interactions. For nonzero frustration, long-range ferromagnetic order is forbidden, and the ground-state of the system consists of phases characterized by periodically modulated structures. At finite temperatures, the phase diagram is calculated within the mean-field approximation. Below the transition line that separates the disordered and the ordered phases, the frustration-temperature phase diagram displays an infinite number of ``flowers'', each flower being made by an infinite number of modulated phases generated by structure combination branching processes. The specificities introduced by the long-range nature of the frustrating interaction and the limitation of the mean-field approach are finally discussed.Comment: 32 pages, 7 figure

Beauty in the Eye of the Home-Owner: Aesthetic Zoning and Residential Property Values

This article empirically confirms one core motivation for architectural zoning: Shape homogeneity among neighboring homes increases the value of residential buildings. Drawing on large-scale shape and transaction data, this study first develops a data-driven measure of architectural similarity, condensing three-dimensional shapes to univariate shape distributions. These algorithm-based similarity estimates are good predictors of human perceptions of shape similarity and are linked to property attributes and transaction prices. For the city of Rotterdam, a price premium of approximately 3.5% is estimated for row houses within very homogeneous ensembles over buildings facing heterogeneous neighbors

7th Drug hypersensitivity meeting: part two

No abstract availabl

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Silica-undersaturated trachytic rocks of central Scotland

The paper presents a review of silica-undersaturated salic intrusions (nepheline-normative trachytes and phonolites) from the Carboniferous-Permian magmatic province in central Scotland. New whole-rock major and trace element analyses, together with Sr and Nd isotopic data, are presented for six intrusions (Bass Rock, North Berwick Law, Traprain Law, Hairy Craig, Fintry and Loudoun Hill) and two syenite autoliths within the Loudoun Hill intrusion. On the basis of the conventional total alkalis versus silica diagram, all six intrusions are trachytes except for Traprain Law, which is a phonolite. Traprain Law is the most highly evolved and the most undersaturated in silica. The Loudoun autoliths are the most basic (Mg numbers of 21.8-27.3) and are inferred to be fragments of cumulates entrained at shallow crustal depths. Whilst all eight samples have approximately constant initial ɛNd (+4.3-+1.99), initial 87Sr/86Sr data are more variable (0.725929-0.709817). Although four of the samples have isotopic characteristics on, or close to, the Sr-Nd mantle array, those from Fintry, Bass Rock, Loudoun Hill and North Berwick Law lie at higher 87Sr/86Sri values, probably as a result of secondary alteration. From their petrographic and geochemical affinity, the six intrusions are considered to have had similar petrogenesis as late-stage residues from mildly silica-deficient basalt magmas, produced in deep crustal chambers and subsequently intruded with minimal crustal interaction