Toroidal Orientifolds in IIA with General NS-NS Fluxes

Type IIA toroidal orientifolds offer a promising toolkit for model builders, especially when one includes not only the usual fluxes from NS-NS and R-R field strengths, but also fluxes that are T-dual to the NS-NS three-form flux. These new ingredients are known as metric fluxes and non-geometric fluxes, and can help stabilize moduli or can lead to other new features. In this paper we study two approaches to these constructions, by effective field theory or by toroidal fibers twisted over a toroidal base. Each approach leads us to important observations, in particular the presence of D-terms in the four-dimensional effective potential in some cases, and a more subtle treatment of the quantization of the general NS-NS fluxes. Though our methods are general, we illustrate each approach on the example of an orientifold of T^6/Z_4.Comment: 59 pages, references adde

T-duality, Generalized Geometry and Non-Geometric Backgrounds

We discuss the action of O(d,d), and in particular T-duality, in the context of generalized geometry, focusing on the description of so-called non-geometric backgrounds. We derive local expressions for the pure spinors descibing the generalized geometry dual to an SU(3) structure background, and show that the equations for N=1 vacua are invariant under T-duality. We also propose a local generalized geometrical definition of the charges f, H, Q and R appearing in effective four-dimensional theories, using the Courant bracket. We then address certain global aspects, in particular whether the local non-geometric charges can be gauged away in, for instance, backgrounds admitting a torus action, as well as the structure of generalized parallelizable backgrounds.Comment: 33 page

A review of the stable isotope bio-geochemistry of the global silicon cycle and its associated trace elements

Silicon (Si) is the second most abundant element in the Earth's crust and is an important nutrient in the ocean. The global Si cycle plays a critical role in regulating primary productivity and carbon cycling on the continents and in the oceans. Development of the analytical tools used to study the sources, sinks, and fluxes of the global Si cycle (e.g., elemental and stable isotope ratio data for Ge, Si, Zn, etc.) have recently led to major advances in our understanding of the mechanisms and processes that constrain the cycling of Si in the modern environment and in the past. Here, we provide background on the geochemical tools that are available for studying the Si cycle and highlight our current understanding of the marine, freshwater and terrestrial systems. We place emphasis on the geochemistry (e.g., Al/Si, Ge/Si, Zn/Si, δ13C, δ15N, δ18O, δ30Si) of dissolved and biogenic Si, present case studies, such as the Silicic Acid Leakage Hypothesis, and discuss challenges associated with the development of these environmental proxies for the global Si cycle. We also discuss how each system within the global Si cycle might change over time (i.e., sources, sinks, and processes) and the potential technical and conceptual limitations that need to be considered for future studies.The work by JS was supported by the “Laboratoire d’Excellence” LabexMER (ANR-10-LABX-19) and co-funded by a grant from the French government under the program “Investissements d’Avenir,” and by a grant from the Regional Council of Brittany (SAD programme). DJC was partially supported by the Knut and Alice Wallenberg Foundation (KAW Wallenberg Scholar) and the Swedish Research Council. This review article has benefited from funding by the European Union Seventh Framework Programme under grant agreement n◦294146 (project MuSiCC, Marie Curie CIG to DC). GdS is supported by a Marie Skłodowska-Curie Research Fellowship under EU Horizon2020 (GA #708407). JuD was supported by the American Chemical Society Petroleum Research Fund (Grant # 53798-DNI2). CE acknowledges financial support by the Institute for Chemistry and Biology of the Marine Environment (Oldenburg, Germany) and the Max Planck Institute for Marine Microbiology (Bremen, Germany). KH is funded by The Royal Society (UF120084) and the European Research Council (ERC-2015-StG - 678371_ICY-LAB). PG acknowledges funding by the Collaborative Research Centre 754 “ClimateBiogeochemistry interactions in the Tropical Ocean” (www. sfb754.de), supported by the Deutsche Forschungsgemeinschaft (DFG)

Has management accounting research been critical?

This paper examines the contributions Management Accounting Research (MAR) has (and has not) made to social and critical analyses of management accounting in the twenty-five years since its launch. It commences with a personalised account of the first named author’s experiences of behavioural, social and critical accounting in the twenty-five years before MAR appeared. This covers events in the UK, especially the Management Control Workshop, Management Accounting Research conferences at Aston, the Inter-disciplinary Perspectives on Accounting Conferences; key departments and professors; and elsewhere the formation of pan-European networks, and reflections on a years’ visit to the USA. Papers published by MAR are analysed according to year of publication, country of author and research site, research method, research subject (type of organization or subject studied), data analysis method, topic, and theory. This revealed, after initial domination by UK academics, increasing Continental European influence; increasing use of qualitative methods over a wide range of topics, especially new costing methods, control system design, change and implementation, public sector transformation, and more recently risk management and creativity. Theoretical approaches have been diverse, often multi-disciplinary, and have employed surprisingly few economic theories relative to behavioural and social theories. The research spans mainly large public and private sector organisations especially in Europe. Seven themes perceived as of interest to a social and critical theory analysis are evaluated, namely: the search for ‘Relevance Lost’ and new costing; management control, the environment and the search for ‘fits’; reconstituting the public sector; change and institutional theory; post-structural, constructivist and critical contributions; social and environmental accounting; and the changing geography of time and space between European and American research. The paper concludes by assessing the contributions of MAR against the aspirations of groups identified in the opening personal historiography, which have been largely met. MAR has made substantial contributions to social and critical accounting (broadly defined) but not in critical areas endeavouring to give greater voice and influence to marginalised sectors of society worldwide. Third Sector organisations, politics, civil society involvement, development and developing countries, labour, the public interest, political economy, and until recently social and environmental accounting have been neglected

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Performance Analysis of Size Scaling on Hybrid Rocket Motors

Hybrid rocket motors are a form of propulsion that combine the principles of liquid engines and solid motors. They offer the low cost and relative simplicity of solid motors while maintaining the liquid engine’s ability to be throttled. Despite these advantages relatively little research has been conducted on the internal mechanics of hybrid motors. This lack of research has led the industry to exclude hybrid propulsion systems from large scale launches, namely in the area of space exploration. This project aims to fill in a portion of this research gap by using a combination of computer simulation and experimental testing to collect data on how size scaling affects the performance of hybrid motors, and to use that data to create a more accurate simulation model. By more closely representing real world results this data will reduce the time, cost, and safety hazards of preparing a hybrid propulsion system for launch. The lasting result of this research will be making hybrid motors and their associated benefits more accessible for future propulsion systems. The test will include four rocket motors; the first motor’s purpose is to acquire experimental values for the hybrid motor simulation. The other three motors will each increase in scale in order to test the effect scale has on a hybrid motors output. POSTER PRESENTATION IGNITE AWAR

Release from biogenic particles, benthic fluxes, and deep water circulation control Cr and δ53Cr distributions in the ocean interior

Chromium (Cr) has shown promise as a paleoceanographic proxy due to the redox-driven control of dissolved Cr concentrations ([Cr]) and stable isotope composition (δ53Cr). To improve the mechanistic understanding of Cr cycling in the modern ocean and strengthen its potential proxy applications, we present new data from regeneration incubations, bottom and sediment pore waters, and a compilation of intermediate and deep water data. While Cr removal and biological export from the surface ocean is associated with organic carbon export, the deep water release of dissolved Cr from sinking particles is not directly dependent on organic carbon respiration, as indicated by differing trends between Cr, oxygen utilization and the regeneration of organic-associated macronutrients (e.g. N, P). Pore water and bottom water data demonstrate that benthic Cr fluxes are locally important and may be significant globally. The pore water dissolved Cr flux at our CaCO3-rich site is likely driven by the re-release of Cr scavenged from the water column by sinking particles, with minor contributions from lithogenic phases. We argue this is consistent with the highest open ocean [Cr] to date being found in the water column below oxygen minimum zones, likely reflecting the release of scavenged Cr in deep waters or surface sediments. Chromium released from suspended particles and surface sediments follows the global δ53Cr–[Cr] array, supporting the proposed role of biological export and regeneration in shaping global Cr and δ53Cr distributions. Global intermediate and deep water [Cr], δ53Cr and Cr:macronutrient relationships are thus shaped by a synergy of circulation patterns, water mass mixing, a deep Cr regeneration cycle, and benthic Cr sources. A biogenic control on global Cr distributions indicates that sedimentary Cr records may reflect biogenic as well as O2-dependent processes, while more research is needed to assess sediment Cr record fidelity based on an active diagenetic cycle

Does urban extent from satellite images relate to symptoms of asthma, rhinoconjunctivitis and eczema in children? A cross-sectional study from ISAAC Phase Three

<p><i>Objective</i>: The relationship between urbanisation and the symptom prevalence of asthma, rhinoconjunctivitis and eczema is not clear, and varying definitions of urban extent have been used. Furthermore, a global analysis has not been undertaken. This study aimed to determine whether the symptom prevalence of asthma, rhinoconjunctivitis and eczema in centres involved in the International Study of Asthma and Allergies in Childhood (ISAAC) were higher in urban than rural centres, using a definition of urban extent as land cover from satellite data. <i>Methods</i>: A global map of urban extent from satellite images (MOD500 map) was used to define the urban extent criterion. Maps from the ISAAC centres were digitised and merged with the MOD500 map to describe the urban percentage of each centre. We investigated the association between the symptom prevalence of asthma, rhinoconjunctivitis and eczema and the percentage of urban extent by centre. <i>Results</i>: A weak negative relationship was found between the percentage of urban extent of each ISAAC centre and current wheeze in the 13–14-year age group. This association was not statistically significant after adjusting for region of the world and gross national income. No other relationship was found between urban extent and symptoms of asthma, rhinoconjunctivitis and eczema. <i>Conclusions</i>: In this study, the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema in children were not associated with urbanisation, according to the land cover definition of urban extent from satellite data. Comparable standardised definitions of urbanisation need to be developed so that global comparisons can be made.</p