549 research outputs found

    Non-eruptive geological hazards of dormant volcanoes: Sao Miguel, Azores Perigos geologicos nao erurptivos en vulcoes adormecidos: Sao Miguel, Acores

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    São Miguel Island presents a diversity of geological hazards that are related to non-eruptive processes. Frequent seismic swarms and destructive earthquakes, of volcanic and tectonically related origin, have been recorded on the Island since it was settled in the 15th century. Large areas of volcanic edifices of Sete Cidades, Fogo and Furnas are unstable. Steep slopes, unconsolidated and poorly consolidated materials, such as volcaniclastic deposits occasionally weathered by hydrothermal activity, play an important role in landslide activity. Slope instability is mainly triggered by intense rainfall, but also by seismic activity, sea and fluvial erosion and/or anthropogenic activity. Volcano degassing represents a major risk during anomalous gas release and a continuous menace for the public health

    Volcanic hazard vulnerability on Sao Miguel Island, Azores

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    "In recent years much progress has been made in researching a wide variety of extreme events on S. Miguel. In addition there are a number of volcano-related risks which impact upon the people of S. Miguel. Some of these may occur both before and during volcanic emergencies (e.g. earthquakes), whilst others render S. Miguel dangerous even when its volcanoes are not erupting (e.g. flooding, landslides, tsunamis and health impacts, especially the effects of CO2 seepage into dwellings). In this chapter we first define what vulnerability means to the people of São Miguel, and relate this to the cultural and economic characteristics of the island. The following aspects of vulnerability are discussed: a. physical (i.e. housing, settlement and the characteristics of evacuation routes and plans); b. demographic and economic; c. social and cultural and perceptual (i.e. do people have an accurate cognition of risk). Particular areas of concern relate to housing; the identification of isolated dwellings which would be difficult to evacuate; the vulnerability/resilience of evacuation routes following recent infrastructure improvements; characteristics of the island's transient population; management of livestock under emergency conditions; local leadership roles and educational outreach.

    Within-species trade-offs in plant-stimulated soil enzyme activity and growth, flowering, and seed size

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    Soil microbial communities affect species demographic rates of plants. In turn, plants influence the composition and function of the soil microbiome, potentially resulting in beneficial feedbacks that alter their fitness and establishment. For example, differences in the ability to stimulate soil enzyme activity among plant lineages may affect plant growth and reproduction. We used a common garden study to test differences in plant-stimulated soil enzyme activity between lineages of the same species across developmental stages. Lineages employed different strategies whereby growth, days to flowering and seed size traded-off with plant-stimulated soil enzyme activity. Specifically, the smaller seeded lineage stimulated more enzyme activity at the early stage of development and flowered earlier while the larger seeded lineage sustained lower but consistent enzyme activity through development. We suggest that these lineages, which are both successful invaders, employ distinct strategies (a colonizer and a competitor) and differ in their influence on soil microbial activity. Synthesis. The ability to influence the soil microbial community by plants may be an important trait that trades off with growth, flowering, and seed size for promoting plant establishment, reproduction, and invasion

    Heme Oxygenase-1 Expression Affects Murine Abdominal Aortic Aneurysm Progression.

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    Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is a cytoprotective enzyme upregulated in the vasculature by increased flow and inflammatory stimuli. Human genetic data suggest that a diminished HO-1 expression may predispose one to abdominal aortic aneurysm (AAA) development. In addition, heme is known to strongly induce HO-1 expression. Utilizing the porcine pancreatic elastase (PPE) model of AAA induction in HO-1 heterozygous (HO-1+/-, HO-1 Het) mice, we found that a deficiency in HO-1 leads to augmented AAA development. Peritoneal macrophages from HO-1+/- mice showed increased gene expression of pro-inflammatory cytokines, including MCP-1, TNF-alpha, IL-1-beta, and IL-6, but decreased expression of anti-inflammatory cytokines IL-10 and TGF-beta. Furthermore, treatment with heme returned AAA progression in HO-1 Het mice to a wild-type profile. Using a second murine AAA model (Ang II-ApoE-/-), we showed that low doses of the HMG-CoA reductase inhibitor rosuvastatin can induce HO-1 expression in aortic tissue and suppress AAA progression in the absence of lipid lowering. Our results support those studies that suggest that pleiotropic statin effects might be beneficial in AAA, possibly through the upregulation of HO-1. Specific targeted therapies designed to induce HO-1 could become an adjunctive therapeutic strategy for the prevention of AAA disease

    The Properties of Fast Yellow Pulsating Supergiants: FYPS Point the Way to Missing Red Supergiants

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    Fast yellow pulsating supergiants (FYPS) are a recently-discovered class of evolved massive pulsator. As candidate post-red supergiant objects, and one of the few classes of pulsating evolved massive stars, these objects have incredible potential to change our understanding of the structure and evolution of massive stars. Here we examine the lightcurves of a sample of 126 cool supergiants in the Magellanic Clouds observed by the Transiting Exoplanet Survey Satellite (\tess~) in order to identify pulsating stars. After making quality cuts and filtering out contaminant objects, we examine the distribution of pulsating stars in the Hertzprung-Russel (HR) diagram, and find that FYPS occupy a region above logL/L5.0\log L/L_\odot \gtrsim 5.0. This luminosity boundary corresponds to stars with initial masses of \sim18-20 MM_\odot, consistent with the most massive red supergiant progenitors of supernovae (SNe) II-P, as well as the observed properties of SNe IIb progenitors. This threshold is in agreement with the picture that FYPS are post-RSG stars. Finally, we characterize the behavior of FYPS pulsations as a function of their location in the HR diagram. We find low frequency pulsations at higher effective temperatures, higher frequency pulsations at lower temperatures, with a transition between the two behaviors at intermediate temperatures. The observed properties of FYPS make them fascinating objects for future theoretical study.Comment: Consistent with published version which contains significantly improved detection and rejection of contaminant objects. Comments welcom

    The role of religion in shaping responses to earthquakes and volcanic eruptions: a comparison between Southern Italy and the Azores, Portugal

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    In contrast to the situation only a few years ago, the case for religion being accepted as a vital element in the cultural responses to disasters has been largely accepted by both academic writers and international agencies, such as the International Federation of Red Cross and Red Crescent Societies. Religions are far more varied in their approaches to natural catastrophes than is frequently recognised or acknowledged by academic writers who are trained and socialised within a 'western' post-Enlightenment tradition. In this paper we seek to demonstrate how detailed religious responses to earthquakes and volcanic eruptions vary even between two societies, southern Italy and the Azores, which are broadly similar in terms of their southern European Catholic religiosity. In southern Italy, popular Catholicism has conflated two approaches to theodicy: the retributive and the Augustinianism (i.e. free-will). Divine wrath may be propitiated through piety and Christian action, which includes worship, repentance, changed conduct and is often associated with well-choreographed ritualistic actions, some of the latter being far removed from Catholic orthodoxy. Such reactions to disaster are not confined to the past but remain strongly embedded in present-day practice. In the Azores a combination of: a history of a better educated and more enlightened church leadership; greater emphasis on praxis following disasters; the growth of the distinctive, egalitarian and pastorally focused Cult do Esparto Santo (i.e. Cult of the Holy Spirit) and the spread of alternative models of theodicy through educational outreach, has produced a strongly contrasting religious response. We conclude that, in the case of the Azores the religious milieu favours active collaboration between the Catholic faith community and the Civil Defence authorities in the aftermath of disasters, whereas this is not the case in southern Italy, although there are some recent signs of change

    The older volcanic complexes of Sao Miguel, Azores: Nordeste and Povoacao

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    The oldest part of S. Miguel is to the east of Furnas. Previous research argued that these volcanics belong to a construct called the Nordeste Volcano, a heavily eroded shield which not only extends to the east coast of the island but also underlies Furnas Volcano in the west. On the basis of geomorphological mapping, we argue that Nordeste comprises two volcanic systems: an older Nordeste construct (the Nordeste Volcanic System); and the younger Povoação Volcano which straddles the Nordeste shield on its western margin. The Nordeste Volcanic System consists of the Lower Basalts which constitute the overwhelming majority of its subaerial products which are exposed in coastal cliff sections. Above the Lower Basalts is a surficial drape of Ankaramites and the Upper Basalts. There is no evidence of large explosive trachytic eruptions from Nordeste Volcanic System. Povoação Volcano comprises an early shield construct, after which the volcano experienced caldera collapse. Post-caldera deposits are poorly exposed, but include basaltic, mugearitic and trachytic lavas intercalated by cut and fill sequences. Radiometric dating has yet to resolve fully the absolute ages of the Nordeste and Povoação volcanic systems, but morphology indicates that the former is much older than the latter

    Unifying soil organic matter formation and persistence frameworks: the MEMS model

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    Soil organic matter (SOM) dynamics in ecosystem-scale biogeochemical models have traditionally been simulated as immeasurable fluxes between conceptually defined pools. This greatly limits how empirical data can be used to improve model performance and reduce the uncertainty associated with their predictions of carbon (C) cycling. Recent advances in our understanding of the biogeochemical processes that govern SOM formation and persistence demand a new mathematical model with a structure built around key mechanisms and biogeochemically relevant pools. Here, we present one approach that aims to address this need. Our new model (MEMS v1.0) is developed from the Microbial Efficiency-Matrix Stabilization framework, which emphasizes the importance of linking the chemistry of organic matter inputs with efficiency of microbial processing and ultimately with the soil mineral matrix, when studying SOM formation and stabilization. Building on this framework, MEMS v1.0 is also capable of simulating the concept of C saturation and represents decomposition processes and mechanisms of physico-chemical stabilization to define SOM formation into four primary fractions. After describing the model in detail, we optimize four key parameters identified through a variance-based sensitivity analysis. Optimization employed soil fractionation data from 154 sites with diverse environmental conditions, directly equating mineral-associated organic matter and particulate organic matter fractions with corresponding model pools. Finally, model performance was evaluated using total topsoil (0–20&thinsp;cm) C data from 8192 forest and grassland sites across Europe. Despite the relative simplicity of the model, it was able to accurately capture general trends in soil C stocks across extensive gradients of temperature, precipitation, annual C inputs and soil texture. The novel approach that MEMS v1.0 takes to simulate SOM dynamics has the potential to improve our forecasts of how soils respond to management and environmental perturbation. Ensuring these forecasts are accurate is key to effectively informing policy that can address the sustainability of ecosystem services and help mitigate climate change.</p

    Differential Growth Responses of Soil Bacterial Taxa to Carbon Substrates of Varying Chemical Recalcitrance

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    Soils are immensely diverse microbial habitats with thousands of co-existing bacterial, archaeal, and fungal species. Across broad spatial scales, factors such as pH and soil moisture appear to determine the diversity and structure of soil bacterial communities. Within any one site however, bacterial taxon diversity is high and factors maintaining this diversity are poorly resolved. Candidate factors include organic substrate availability and chemical recalcitrance, and given that they appear to structure bacterial communities at the phylum level, we examine whether these factors might structure bacterial communities at finer levels of taxonomic resolution. Analyzing 16S rRNA gene composition of nucleotide analog-labeled DNA by PhyloChip microarrays, we compare relative growth rates on organic substrates of increasing chemical recalcitrance of >2,200 bacterial taxa across 43 divisions/phyla. Taxa that increase in relative abundance with labile organic substrates (i.e., glycine, sucrose) are numerous (>500), phylogenetically clustered, and occur predominantly in two phyla (Proteobacteria and Actinobacteria) including orders Actinomycetales, Enterobacteriales, Burkholderiales, Rhodocyclales, Alteromonadales, and Pseudomonadales. Taxa increasing in relative abundance with more chemically recalcitrant substrates (i.e., cellulose, lignin, or tannin–protein) are fewer (168) but more phylogenetically dispersed, occurring across eight phyla and including Clostridiales, Sphingomonadalaes, Desulfovibrionales. Just over 6% of detected taxa, including many Burkholderiales increase in relative abundance with both labile and chemically recalcitrant substrates. Estimates of median rRNA copy number per genome of responding taxa demonstrate that these patterns are broadly consistent with bacterial growth strategies. Taken together, these data suggest that changes in availability of intrinsically labile substrates may result in predictable shifts in soil bacterial composition

    Influence of the 6^1S_0-6^3P_1 Resonance on Continuous Lyman-alpha Generation in Mercury

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    Continuous coherent radiation in the vacuum-ultraviolet at 122 nm (Lyman-alpha) can be generated using sum-frequency mixing of three fundamental laser beams in mercury vapour. One of the fundamental beams is at 254 nm wavelength, which is close to the 6^1S_0-6^3P_1 resonance in mercury. Experiments have been performed to investigate the effect of this one-photon resonance on phasematching, absorption and the nonlinear yield. The efficiency of continuous Lyman-alpha generation has been improved by a factor of 4.5.Comment: 8 pages, 7 figure
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