188 research outputs found

    Bryozoan beds in northern Italy as a shallow-water expression of environmental changes during the Oligocene isotope event 1

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    Shifts in carbonate-producing biotic communities in the geological record provide evidence of past environmental changes in the neritic realm. The shallow-marine Calcare di Nago Formation exposed in the San Valentino section (northern Italy) covers the Late Eocene and Earliest Oligocene. The succession is characterized by the occurrence of light-dependent biota such as coralline algae and larger benthic foraminifera. In the uppermost part of the section, however,\ the fossil association is dominated by bryozoans, which are filter-feeder organisms. This ca. 12 m thick interval locally contains up to 86% bryozoans, while coralline algae as well as larger benthic foraminifera are absent. Coralline algae and nummulitid foraminifera recover in the upper part of the bryozoan beds, whereas orthophragminids do not recover. The gradual disappearance of larger foraminifera and coralline algae within the bryozoan-dominated deposits is coeval with a pronounced positive shift in δ¹³C. Based on its biostratigraphic position, this positive shift is interpreted to be linked to the positive shift in δ¹³C recognized in deep-sea records shortly above the Eocene–Oligocene boundary, which in turn is associated to the positive shift in δ¹⁸O leading to the Oi-1 (Oligocene isotope event 1) cooling phase. Total phosphorus content increases in the bryozoan beds, suggesting enhanced nutrient supply to the neritic ecosystem. This phosphorous peak is coeval with the globally recognized increment in ocean productivity around the Oi-1 and δ¹³C positive shift. Thus, disappearance of light-dependent biota and the dominance of bryozoans in the platform carbonates studied are interpreted to result not necessarily from a deepening of the depositional environment but from the combination of lower sea-surface temperatures and the deterioration of underwater light conditions on account of elevated turbidity in surface waters, resulting from enhanced primary productivity. As bryozoan beds occur in several Italian localities around the Eocene–Oligocene boundary, they are interpreted to represent the regional expression of neritic carbonate depositional systems to global environmental changes occurring at the dawn of an ice-house Earth

    Bryozoan beds in northern Italy as a shallow-water expression of environmental changes during Oligocene isotope event 1

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    Shifts in carbonate-producing biotic communities in the geological record provide evidence of past environmental changes in the neritic realm. The shallow-marine Calcare di Nago Formation exposed in the San Valentino section (northern Italy) covers the Late Eocene and Earliest Oligocene. The succession is characterized by the occurrence of light-dependent biota such as coralline algae and larger benthic foraminifera. In the uppermost part of the section, however,\ the fossil association is dominated by bryozoans, which are filter-feeder organisms. This ca. 12 m thick interval locally contains up to 86% bryozoans, while coralline algae as well as larger benthic foraminifera are absent. Coralline algae and nummulitid foraminifera recover in the upper part of the bryozoan beds, whereas orthophragminids do not recover. The gradual disappearance of larger foraminifera and coralline algae within the bryozoan-dominated deposits is coeval with a pronounced positive shift in δ13C. Based on its biostratigraphic position, this positive shift is interpreted to be linked to the positive shift in δ13C recognized in deep-sea records shortly above the Eocene-Oligocene boundary, which in turn is associated to the positive shift in δ18O leading to the Oi-1 (Oligocene isotope event 1) cooling phase. Total phosphorus content increases in the bryozoan beds, suggesting enhanced nutrient supply to the neritic ecosystem. This phosphorous peak is coeval with the globally recognized increment in ocean productivity around the Oi-1 and δ13C positive shift. Thus, disappearance of light-dependent biota and the dominance of bryozoans in the platform carbonates studied are interpreted to result not necessarily from a deepening of the depositional environment but from the combination of lower sea-surface temperatures and the deterioration of underwater light conditions on account of elevated turbidity in surface waters, resulting from enhanced primary productivity. As bryozoan beds occur in several Italian localities around the Eocene-Oligocene boundary, they are interpreted to represent the regional expression of neritic carbonate depositional systems to global environmental changes occurring at the dawn of an ice-house Earth

    On airborne tire wear particles along roads with different traffic characteristics using passive sampling and optical microscopy, single particle SEM/EDX, and µ-ATR-FTIR analyses

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    Tire wear particles (TWPs) are a major category of microplastic pollution produced by friction between tires and road surfaces. This non-exhaust particulate matter (PM) is transported through the air and with runoff leading to environmental pollution and health concerns. Here, we collected airborne PM along paved roads with different traffic volumes and speeds using Sigma-2 passive samplers. Particles entering the samplers deposit onto substrates for analysis, or, as we modified it, directly into small (60 ml) separatory funnels, which is particularly useful with high particle loads, where a density separation aids in isolating the microplastics. We quantified putative TWPs (∼10–80 µm) deposited on the substrates (primarily adhesive tape on glass slides) and in the funnels using stereomicroscopy. Putative TWP deposition rates (particles/cm2/day ± SD) at 5 m from the road were highest near a busy highway (324 ± 129), followed by a boulevard with moderate traffic (184 ± 93), and a slow traffic avenue (29 ± 7). We observed that deposition rates increased within proximity to the highway: 99 ± 54, 180 ± 88, and 340 ± 145 at 30, 15, and 5 m, respectively. We show that TWP abundances (i.e., deposition and mass concentration) increase with vehicle braking (driving behavior). We observed no differences (p \u3e 0.05) between the separatory funnel and adhesive tape collection methods. In addition, we were able to obtain FTIR spectra of TWPs (\u3e10 µm) using µ-ATR-FTIR. Both deserve further scrutiny as novel sampling and analytical approaches. In a separate sampling campaign, we differentiated 1438 particles (∼1–80 µm) deposited on boron substrates into TWP, metal, mineral, and biogenic/organic classes with single particle SEM/EDX analysis based on morpho-textural-chemical classification and machine learning. The results revealed similar concentration trends with traffic (high \u3e moderate \u3e low), with the distribution of particle sources alike for the highway and the moderate road: TWPs (∼38–39%) \u3e biogenic (∼34–35%) \u3e minerals (∼23–26%), and metallic particles (∼2–3%). The low traffic road yielded a much different distribution: biogenic (65%) \u3e minerals (27%) \u3e TWPs (7%) \u3e metallic particles (1%). Overall, this work provides much-needed empirical data on airborne TWPs along different types of roads

    Differentiating and quantifying carbonaceous (tire, bitumen, and road marking wear) and non-carbonaceous (metals, minerals, and glass beads) non-exhaust particles in road dust samples from a traffic environment

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    Tires, bitumen, and road markings are important sources of traffic-derived carbonaceous wear particles and microplastic (MP) pollution. In this study, we further developed a machine-learning algorithm coupled to an automated scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analytical approach to classify and quantify the relative number of the following subclasses contained in environmental road dust: tire wear particles (TWP), bitumen wear particles (BiWP), road markings, reflecting glass beads, metallics, minerals, and biogenic/organics. The method is non-destructive, rapid, repeatable, and enables information about the size, shape, and elemental composition of particles 2–125 μm. The results showed that the method enabled differentiation\ua0between TWP and BiWP for particles > 20 μm with satisfying results. Furthermore, the relative number concentration of the subclasses was similar in both analyzed size fractions (2–20 μm and 20–125 μm), with minerals as the most dominant subclass (2–20 μm x̄ = 78%, 20–125 μm x̄ = 74%) followed by tire and bitumen wear particles, TBiWP, (2–20 μm x̄ = 19%, 20–125 μm x̄ = 22%). Road marking wear, glass beads, and metal wear contributed to x̄ = 1%, x̄ = 0.1%, and x̄ = 1% in the 2–20-μm fraction and to x̄ = 0.5%,x̄ = 0.2%, and x̄ = 0.4% in the 20–125-μm fraction. The present results show that road dust appreciably consists of TWP and BiWP within both the coarse and the fine size fraction. The study delivers quantitative evidence of the importance of tires, bitumen, road marking, and glass beads besides minerals and metals to wear particlesand MP pollution in traffic environments based on environmental (real-world) sample

    Pleistocene aragonite crust diagenesis mimics microbialite fabrics (Danakil Depression, Ethiopia)

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    Fibrous aragonite crusts occur in two consecutive Pleistocene successions in the Danakil Depression (Afar, Ethiopia). Lateral transitions between pristine and altered fibrous aragonite crusts document changes in texture associated with diagenesis. Crusts formed as essentially abiotic seafloor precipitates at the transition from marine to evaporitic conditions. Diagenesis started with the dissolution of aragonite fans at the interface between single fans in non-laminated crusts and along lamination planes in isopachous, irregular, or crudely laminated crusts. Incomplete dissolution resulted in the development of secondary porosity within a matrix of undissolved aragonite fibers. Subsequently, the porosity was filled with calcite that systematically encased remaining aragonite crystals. This was followed by the dissolution of remnant aragonite fibers, producing a network of elongated inter- and intracrystalline pores that were eventually filled with low-Mg calcite. The stepwise substitution of fibrous aragonite by low-Mg calcite resulted in sparry, sparry-cloudy, sparry-micritic (including clotted micrite), and peloidal textures, which obscure the fibrous nature of the original deposits. Stable C- and O-isotope compositions suggest that early diagenesis was driven by meteoric and evaporative fluids. These observations unequivocally demonstrate destructive diagenesis, resulting in secondary textures, which mimic micritic and grumous (peloidal and clotted) textures associated with sparry microfabrics. This suggests that these textures, classically interpreted as primary microbial precipitates and used as evidence of biogenicity in ancient microbialites, might be diagenetic products in some cases, even though at some stage, microbial processes and/or degradation of organic matter could have been involved in the diagenetic process

    Community-Based Climate Change Adaptation Action Plans to Support Climate-Resilient Development in the Eastern African Highlands

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    Smallholder farmers in the Eastern African Highlands depend on rain-fed agriculture for their livelihoods. Climate adaptation and sustainable development goals must be targeted in an integrated way to better match farmers’ realities and address local priorities and vulnerabilities in these areas. To support climate-resilient development in the Eastern African Highlands, 224 local stakeholders were engaged in the development of community-based climate change adaptation action plans for the Jimma Highlands in Ethiopia, Taita Hills in Kenya and Mount Kilimanjaro in Tanzania. Participatory methods, high-resolution climate projections and the United Nations Development Programme’s (UNDP’s) guidelines were used in the design of these climate action plans with specific objectives to: 1) engage stakeholders to increase understanding of climate change impacts, adaptation options and their potential trade-offs, 2) build their capacities to design climate change adaptation projects, 3) empower stakeholders to identify existing vulnerabilities and enhance climate resilience and 4) strengthen networks to facilitate information access and sharing. Increased risk of water stress and reduction of agricultural productivity were the most frequently identified climate-change-induced problems in the three areas. The developed action plans target the underlying causes of these problems and describe sector-specific responses, activities, critical barriers and opportunities and support the National Adaptation Programmes of Action.Peer reviewe

    Pleistocene sea-floor fibrous crusts and spherulites in the Danakil Depression (Afar, Ethiopia)

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    Pleistocene fibrous aragonite fabrics, including crusts and spherules, occur in the Danakil Depression (Afar, Ethiopia) following the deposition of two distinctive Middle and Late Pleistocene coralgal reef units and pre‐dating the precipitation of evaporites. Crusts on top of the oldest reef unit (Marine Isotope Stage 7) cover and fill cavities within a red algal framework. The younger aragonite crusts directly cover coralgal bioherms (Marine Isotope Stage 5) and associated deposits. Their stratigraphic position between marine and evaporitic deposits, and their association to euryhaline molluscs, suggest that the crusts and spherules formed in restricted semi‐enclosed conditions. The availability of hard substrate controls crust formation with crusts more often found on steep palaeo‐slopes, from sea level up to at least 80 m depth, while spherules mainly occur associated with mobile substrate. Crusts reach up to 30 cm in thickness and can be microdigitate, columnar (branching and non‐branching) or non‐ columnar, with laminated and non‐laminated fabrics. Two different lamination types are found within the crystalline fabrics: (i) isopachous lamination; and (ii) irregular lamination. These two types of lamination can be distinguished by the organization of the aragonite fibres, as well as the lateral continuity of the laminae. Scanning electron microscopy with energy dispersive X‐ray spectroscopy analyses on well‐preserved samples revealed the presence of Mg‐silicate laminae intercalated with fibrous aragonite, as well as Mg‐silicate aggregates closely associated with the fibrous aragonite crusts and spherules. The variety of observed fabrics results from a continuum of abiotic and microbial processes and, thus, reflects the tight interaction between microbially mediated and abiotic mineralization mechanisms. These are the youngest known isopachously laminated, digitate and columnar branching fibrous crusts associated with a transition from marine to evaporitic conditions. Understanding the context of formation of these deposits in Afar can help to better interpret the depositional environment of the widespread Precambrian sea‐floor precipitates

    A propósito del consenso para el manejo de las disfunciones tiroideas mínimas

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    Resumen El hipotiroidismo subclínico y sus consecuencias clínicas ha sido objeto de debate científico por espacio de varias décadas. A raíz de la publicación de la declaración de consenso acerca de la disfunción tiroidea sub- clínica en el año 2005, realizada por la Sociedad Americana de Endocrinologìa (The Endocrine Society), la Asociación Americana de Endocrinólogos Clínicos (AACE) y la Asociación Americana de la Tiroides (ATA) se abrió un nuevo espacio para los endocrinólogos en el manejo de algunas disfunciones tiroideas que no habían sido tenidas en cuenta dentro del campo de accion terapéutico. Los autores hacen un recuento de cómo se produce el cambio en los paradigmas y en el enfoque diagnostico y terapéutico. Luego hacen un recuento de algunas de las experiencias desarrolladas en Colombia. Finalmente sugieren algunos derroteros a partir de su propia experiencia y también basa- dos en logros científicos de otras fuentes obtenidos en otros campos de la Endocrinologìa moderna. Palabras claves: Hipotiroidismo. Abstract Subclinical hypothyroidism and its clinical consequences have been debated during several decades. With the publication of the Consensus Declaration about subclinical thyroid dysfunction by the Endocrine Society, the American Association of Clinical Endocrinologists (AACE), and the American Thyroid Association (ATA), a new field was open for endocrinologist in the management of some long ignored thyroid dysfunctions that did not have any thera- peutic solution. The authors describe the paradigm shift and the changes in the diagnostic and therapeutic approaches. Later they recount some experiences developed in Colombia, S.A. Finally, they suggest some guidelines from their own experience and from other sources obtained in different fields of modern endocrinology. Key words: Hypothyroidism

    Exploring the Dynamics and Mutational Landscape of Riboregulation with a Minimal Synthetic Circuit in Living Cells

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    [EN] The regulation of gene expression, triggered by conformational changes in RNA molecules, is widely observed in cellular systems. Here, we examine this mode of control by means of a model-based design and construction of a fully synthetic riboregulatory device. We present a theoretical framework that rests on a simple energy model to predict the dynamic response of such a system. Following an equilibrium description, our framework integrates thermodynamic properties-anticipated with an RNA physicochemical model-with a detailed description of the intermolecular interaction. The theoretical calculations are confirmed with an experimental characterization of the action of the riboregulatory device within living cells. This illustrates, more broadly, the predictability of genetic robustness on synthetic systems, and the faculty to engineer gene expression programs from a minimal set of first principles.This work was supported by the AXA Research Fund and the CSIC Intramural grant No. 201440I017 to G.R., the Spanish Ministry of Education, Culture and Sports FPU fellowship AP2012-3751 to E.M., the Spanish Ministry of Economy and Competitiveness grants No. AGL2013-49919-EXP and No. BIO2011-26741 to J.-A.D. and No. BFU2011-24691 to J.F.P., and the European Union grant No. FP7-KBBE-613745 (Programming synthetic networks for bio-based production of value chemicals) to A.J.Rodrigo Tarrega, G.; Majer, E.; Prakash, S.; Daros Arnau, JA.; Jaramillo, A.; Poyatos, JF. (2015). Exploring the Dynamics and Mutational Landscape of Riboregulation with a Minimal Synthetic Circuit in Living Cells. Biophysical Journal. 109(5):1070-1076. https://doi.org/10.1016/j.bpj.2015.07.021S10701076109
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