Abelian duality on globally hyperbolic spacetimes

We study generalized electric/magnetic duality in Abelian gauge theory by combining techniques from locally covariant quantum field theory and Cheeger-Simons differential cohomology on the category of globally hyperbolic Lorentzian manifolds. Our approach generalizes previous treatments using the Hamiltonian formalism in a manifestly covariant way and without the assumption of compact Cauchy surfaces. We construct semi-classical configuration spaces and corresponding presymplectic Abelian groups of observables, which are quantized by the CCR-functor to the category of C*-algebras. We demonstrate explicitly how duality is implemented as a natural isomorphism between quantum field theories. We apply this formalism to develop a fully covariant quantum theory of self-dual fields

Quantum charges and spacetime topology: The emergence of new superselection sectors

In which is developed a new form of superselection sectors of topological origin. By that it is meant a new investigation that includes several extensions of the traditional framework of Doplicher, Haag and Roberts in local quantum theories. At first we generalize the notion of representations of nets of C*-algebras, then we provide a brand new view on selection criteria by adopting one with a strong topological flavour. We prove that it is coherent with the older point of view, hence a clue to a genuine extension. In this light, we extend Roberts' cohomological analysis to the case where 1--cocycles bear non trivial unitary representations of the fundamental group of the spacetime, equivalently of its Cauchy surface in case of global hyperbolicity. A crucial tool is a notion of group von Neumann algebras generated by the 1-cocycles evaluated on loops over fixed regions. One proves that these group von Neumann algebras are localized at the bounded region where loops start and end and to be factorial of finite type I. All that amounts to a new invariant, in a topological sense, which can be defined as the dimension of the factor. We prove that any 1-cocycle can be factorized into a part that contains only the charge content and another where only the topological information is stored. This second part resembles much what in literature are known as geometric phases. Indeed, by the very geometrical origin of the 1-cocycles that we discuss in the paper, they are essential tools in the theory of net bundles, and the topological part is related to their holonomy content. At the end we prove the existence of net representations

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

Perdas de nutrientes via subsuperfície em colunas de solo sob fertilização mineral e orgânica Nutrient losses via leaching from soil columns submitted to mineral and organic fertilization

O uso de dejetos de animais na produção agrícola pode ocasionar a contaminação ou poluição das águas por nutrientes, principalmente com aplicações consecutivas na mesma área. Nesse sentido, o objetivo deste trabalho foi avaliar o efeito da aplicação de dejeto líquido de bovinos e fertilizantes minerais na lixiviação de NH4+, NO3-, P e K. Para essa avaliação, foram coletadas colunas indeformadas de solo, num experimento de campo que estava sendo conduzido por sete anos consecutivos e que continha 12 tratamentos, resultantes da combinação de quatro doses de dejeto líquido de bovinos com três doses de fertilizante mineral. O experimento de campo era conduzido num Latossolo Bruno distrófico em sistema de plantio direto com sorgo, milho, aveia-preta e azevém em rotação. Em laboratório, essas colunas, de acordo com os respectivos tratamentos de campo, foram submetidas à aplicação do dejeto líquido de bovinos (0, 30, 60 e 90 m³ ha-¹, aplicados em dose única) e dos fertilizantes minerais (0, 50 e 100 % da dose recomendada para o milho - 120, 60 e 60 kg ha-1 de N, P2O5 e K2O). Imediatamente após a aplicação de dejeto e fertilizante, a água percolada por coluna foi coletada e analisada em cinco turnos contínuos, totalizando 516 mm - aproximadamente três volumes de poros. Constatou-se aumento nas concentrações de N-NH4+, P e K com as doses de dejeto e aumento de N-NO3- e K com as doses de fertilizante mineral. No entanto, com exceção do N-NO3-, as concentrações de N-NH4+ e P estiveram abaixo do limite máximo permitido pela legislação brasileira, indicando a importância da infiltração de água no solo na redução do potencial poluidor dos dejetos.<br>The use of animal manure in agricultural systems can cause water contamination and/or pollution by nutrients, especially by consecutive applications to the same area. In view thereof, the purpose of this study was to evaluate the effect of manure and fertilizer application on NH4+, NO3-, P and K leaching. For this evaluation, undisturbed soil columns were collected from a seven-year field experiment that consisted of 12 treatments, resulting from the combinations of four doses of dairy slurry with three doses of mineral fertilizers. The study has been conducted on an Oxisol under no-till system with a crop rotation including sorghum, corn, oat and ryegrass. The leaching experiment was conducted in a laboratory with the undisturbed soil columns collected in the field experiment. In the laboratory, these soil columns, analogously to the respective field treatments, were treated with dairy slurry manure (0, 30, 60 and 90 m³ ha-¹ applied in a single dose) and mineral fertilizers (0, 50 and 100 % of the recommended dose for corn - 120 kg of N, 60 kg of P2O5 and 60 kg of K2O per ha) application. Immediately after manure and fertilizer application, the percolated water was sampled and analyzed in five continuous periods, totalling 516 mm, which corresponded to approximately three pore volumes. An increase of NH4-N, P, and K with increasing manure doses and an increment in NO3-N and K with the higher mineral fertilizer doses was observed. However, in general, except for NO3-N, the NH4-N and P concentrations were below the limit value determined by the Brazilian legislation, indicating the importance of soil-water infiltration to reduce the manure pollution potential

Basis of selective predation by the aquatic larvae of the salamander, Ambystoma tigrinum

The effect of several factors on feeding selectivity by three size classes of larvae of Ambystoma tigrinum (Green) was examined. Five types of invertebrate prey were used: Chaoborus, Daphnia, damselflies, Hyalella and water boatmen. Five variables were examined in relation to the electivity indices associated with each prey type: ease of prey consumption, ease of prey capture, relative prey size, prey activity, and microhabitat overlap. No single variable explained the observed electivity. For small larvae (snout-vent length, SVL,6.5cm), ease of prey consumption, prey activity, and relative prey size predicted electivity values. However, none of the measured variables was related to electivity values found for medium sized larvae (SVL \u3e3.5 and \u3c5.5cm)