5,583 research outputs found
Minimal Supergravity and the supersymmetry of Arnold-Beltrami Flux branes
In this paper we study some properties of the newly found Arnold-Beltrami
flux-brane solutions to the minimal supergravity. To this end we first
single out the appropriate Free Differential Algebra containing both a gauge
-form and a gauge -form : then we
present the complete rheonomic parametrization of all the generalized
curvatures. This allows us to identify two-brane configurations with
Arnold-Beltrami fluxes in the transverse space with exact solutions of
supergravity and to analyze the Killing spinor equation in their background. We
find that there is no preserved supersymmetry if there are no additional
translational Killing vectors. Guided by this principle we explicitly construct
Arnold-Beltrami flux two-branes that preserve , and of the
original supersymmetry. Two-branes without fluxes are instead BPS states and
preserve supersymmetry. For each two-brane solution we carefully study
its discrete symmetry that is always given by some appropriate crystallographic
group . Such symmetry groups are transmitted to the
gauge theories on the brane world--volume that occur in the gauge/gravity
correspondence. Furthermore we illustrate the intriguing relation between gauge
fluxes in two-brane solutions and hyperinstantons in topological
sigma-models.Comment: 56 pages, LaTeX source, 8 jpg figures, typos correcte
Generalized AdS-Lorentz deformed supergravity on a manifold with boundary
The purpose of this paper is to explore the supersymmetry invariance of a
particular supergravity theory, which we refer to as D=4 generalized
AdS-Lorentz deformed supergravity, in the presence of a non-trivial boundary.
In particular, we show that the so-called generalized minimal AdS-Lorentz
superalgebra can be interpreted as a peculiar torsion deformation of osp(4|1),
and we present the construction of a bulk Lagrangian based on the
aforementioned generalized AdS-Lorentz superalgebra. In the presence of a
non-trivial boundary of space-time, that is when the boundary is not thought of
as set at infinity, the fields do not asymptotically vanish, and this has some
consequences on the invariances of the theory, in particular on supersymmetry
invariance. In this work, we adopt the so-called rheonomic (geometric) approach
in superspace and show that a supersymmetric extension of a Gauss-Bonnet like
term is required in order to restore the supersymmetry invariance of the
theory. The action we end up with can be recast as a MacDowell-Mansouri type
action, namely as a sum of quadratic terms in the generalized AdS-Lorentz
covariant super field-strengths.Comment: 32 pages. Version accepted for publication in The European Physical
Journal Plus (EPJP), Eur. Phys. J. Plus (2018) 133: 514. The final
publication is available at Springer via
https://doi.org/10.1140/epjp/i2018-12335-0. arXiv admin note: text overlap
with arXiv:1802.0660
Editorial: The role of platinum-based antitumor prodrugs in medicinal inorganic chemistry
Editorial on the research topic "The role of platinum-based antitumor prodrugs in medicinal inorganic chemistry
Structuring wicked problems in transdisciplinary research using the Social-Ecological Systems framework: an application to the montado system, Alentejo, Portugal
The aspiration to establish an effective dialogue between science and society has inspired some ground breaking examples of transdisciplinarity (TD). The core idea of TD is that different academic disciplines work jointly with practitioners to solve common problems. The first step of TD implies a contextualization that requires holistic and systemic thinking. To achieve this contextualization, we applied the SocialâEcological Systems (SES) framework with the aim of developing TD to deal with the recorded decline in area and tree density of the montado land-use system located in the Alentejo region, Portugal. The study was based both on a literature review and on the analysis of qualitative and quantitative data collected in a number of research projects on the montado. The results show that the lack of consensus regarding the system boundaries, the diverse range of mental models, and the disconnection between policymaking and system singularities are some of the conditions that can hinder TD efforts. The framework allowed the identification of knowledge gaps that limit the understanding of the problem complexity to be dealt with by a TD research process. There is a need to gain a better understanding of the governance system, and to characterize the different types of agro-silvo-pastoral combinations that can be designated as montado. With this detailed understanding, a tailored TD process can be designed. This work argues for the active use of the SES framework in TD in environmental management. Future research could focus on the frameworkâs utility in developing tools to assess and monitor transdisciplinary research
Evaluating diagnosis and treatment of oral and esophageal candidiasis in Ugandan AIDS patients.
A randomized cross-over clinical and endoscopic evaluation of 85 Ugandan patients showed that esophageal candidiasis in AIDS patients with oral candidiasis could be managed without endoscopy and biopsies. Oral lesions, especially when accompanied by esophageal symptoms, were sufficient for diagnosis. Miconazole was more effective than nystatin in treating esophageal candidiasis and could be a valid alternative to more expensive azolic drugs in developing countries
Climate Science, Development Practice, and Policy Interactions in Dryland Agroecological Systems
The literature on drought, livelihoods, and poverty suggests that dryland residents are especially vulnerable to climate change. However, assessing this vulnerability and sharing lessons between dryland communities on how to reduce vulnerability has proven difficult because of multiple definitions of vulnerability, complexities in quantification, and the temporal and spatial variability inherent in dryland agroecological systems. In this closing editorial, we review how we have addressed these challenges through a series of structured, multiscale, and interdisciplinary vulnerability assessment case studies from drylands in West Africa, southern Africa, Mediterranean Europe, Asia, and Latin America. These case studies adopt a common vulnerability framework but employ different approaches to measuring and assessing vulnerability. By comparing methods and results across these cases, we draw out the following key lessons: (1) Our studies show the utility of using consistent conceptual frameworks for vulnerability assessments even when quite different methodological approaches are taken; (2) Utilizing narratives and scenarios to capture the dynamics of dryland agroecological systems shows that vulnerability to climate change may depend more on access to financial, political, and institutional assets than to exposure to environmental change; (3) Our analysis shows that although the results of quantitative models seem authoritative, they may be treated too literally as predictions of the future by policy makers looking for evidence to support different strategies. In conclusion, we acknowledge there is a healthy tension between bottom-up/ qualitative/place-based approaches and top-down/quantitative/generalizable approaches, and we encourage researchers from different disciplines with different disciplinary languages, to talk, collaborate, and engage effectively with each other and with stakeholders at all levels
An update of the chemiosmotic theory as suggested by possible proton currents inside the coupling membrane
Understanding how biological systems convert and store energy is a primary purpose of basic research. However, despite Mitchell's chemiosmotic theory, we are far from the complete description of basic processes such as oxidative phosphorylation (OXPHOS) and photosynthesis. After more than half a century, the chemiosmotic theory may need updating, thanks to the latest structural data on respiratory chain complexes. In particular, up-to date technologies, such as those using fluorescence indicators following proton displacements, have shown that proton translocation is lateral rather than transversal with respect to the coupling membrane. Furthermore, the definition of the physical species involved in the transfer (proton, hydroxonium ion or proton currents) is still an unresolved issue, even though the latest acquisitions support the idea that protonic currents, difficult to measure, are involved. Moreover, F o F 1 -ATP synthase ubiquitous motor enzyme has the peculiarity (unlike most enzymes) of affecting the thermodynamic equilibrium of ATP synthesis. It seems that the concept of diffusion of the proton charge expressed more than two centuries ago by Theodor von Grotthuss is to be taken into consideration to resolve these issues. All these uncertainties remind us that also in biology it is necessary to consider the Heisenberg indeterminacy principle, which sets limits to analytical questions
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Flipping the Tortilla: Social-ecological innovations and traditional ecological knowledge for more sustainable agri-food systems in Spain
The conventional dominant global agri-food system is a main driver in the Anthropocene: food production entails profound global environmental changes from greenhouse gas emissions to biodiversity loss, and shifting diets further impact planetary and human health. Innovative approaches are needed to shift towards more sustainable, equitable and healthy agri-food systems. Building on the increasing recognition of the relevance of traditional agroecological knowledge (TAeK) in sustainable food systems, this paper aims to describe innovative agri-food initiatives and explore how the use and valorization of TAeK may transform conventional agri-food systems. It employs a case-study approach in Spain, where we conducted semi-structured interviews with 12 representatives of alternative agri-food initiatives. We found that, to promote sustainable agri-food systems, TAeK has to span from farm-to-fork. Innovative agroecological practices and knowledge help to safeguard biocultural diversity, while gastronomic knowledge among consumers on how to process and prepare local varieties and species is crucial for the implementation of shorter value chains. We discuss how TAeK enhances the success of conventional systems of innovation, challenging dominant epistemological frameworks. By scaling deep (changing values), scaling out (dissemination, reproduction) and scaling up (changing institutions), the agri-food initiatives may act on leverage points to enable broader transformation of the Spanish agri-food system
Coexistence of osteopoikilosis with seronegative spondyloarthritis and Raynaud's phenomenon: first case report with evaluation of the nailfold capillary bed and literature review.
Osteopoikilosis (OPK) is a rare autosomal dominant bone disorder characterized by numerous hyperostotic areas that tend to localize in periarticular osseous regions. It is usually asymptomatic and is often diagnosed incidentally during X-rays. OPK may be an isolated finding or associated with other pathologies, e.g. skin manifestations, rheumatic and/or skeletal disorders. We report a literature review and, for the first time, the coexistence of OPK with seronegative spondyloarthritis and Raynaud's phenomenon in a 48-year old female. To the best of our knowledge, this is the first case of OPK studied by videocapillaroscopy, demonstrating the absence of specific microvascular abnormalities of nailfold capillaries
Identifying past social-ecological thresholds to understand long-term temporal dynamics in Spain
A thorough understanding of long-term temporal social-ecological dynamics at the national scale helps to explain the current condition of a countryâs ecosystems and to support environmental policies to tackle future sustainability challenges. We aimed to develop a methodological approach to understand past long-term (1960-2010) social-ecological dynamics in Spain. First, we developed a methodical framework that allowed us to explore complex social-ecological dynamics among biodiversity, ecosystem services, human well-being, drivers of change, and institutional responses. Second, we compiled 21 long-term, national-scale indicators and analyzed their temporal relationships through a redundancy analysis. Third, we used a Bayesian change point analysis to detect evidence of past social-ecological thresholds and historical time periods. Our results revealed that Spain has passed through four socialecological thresholds that define five different time periods of nature and society relationships. Finally, we discussed how the proposed methodological approach helps to reinterpret national-level ecosystem indicators through a new conceptual lens to develop a more systems-based way of understanding long-term social-ecological patterns and dynamicsThis work was supported by the Biodiversity Foundation (http://www.fundacion-biodiversidad.es/) of the Spanish Ministry of Agriculture, Food and Environment. Partial
financial support was also provided by the Ministry of Economy and Competitiveness of Spain (project CGL2014-53782-P: ECOGRADIENTES). The Spanish National Institute for
Agriculture and Food Research and Technology (INIA) funded Marina GarcĂa-Llorente as part of the European Social Fund. Blanca GonzĂĄlez GarcĂa-Mon participated in this article as a âla
Caixaâ Banking Foundation scholar. The funders had no role in the study design, data collection and analysis, preparation of the report, or the decision to submit the study for publicatio
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