1,535 research outputs found

    Geology of the Bottle Lake Complex, Maine

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    Guidebook to the geology of Northeastern Maine and neighboring New Brunswick: The 72nd annual meeting of the New England Intercollegiate Geological Conference, Presque Isle, Maine, October 10-13, 1980: Trip A-

    Remnant Colloform Pyrite at the Haile Gold Deposit, South Carolina: A Textural Key to Genesis

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    Auriferous iron sulfide-bearing deposits of the Carolina slate belt have distinctive mineralogical and textural features—traits that provide a basis to construct models of ore deposition. Our identification of paragenetically early types of pyrite, especially remnant colloform, crustiform, and layered growth textures of pyrite containing electrum and pyrrhotite, establishes unequivocally that gold mineralization was coeval with deposition of host rocks and not solely related to Paleozoic tectonic events. Ore horizons at the Haile deposit, South Carolina, contain many remnants of early pyrite: (1) fine-grained cubic pyrite disseminated along bedding; (2) finegrained spongy, rounded masses of pyrite that may envelop or drape over pyrite cubes; (3) fragments of botryoidally and crustiform layered pyrite, and (4) pyritic infilling of vesicles and pumice. Detailed mineral chemistry by petrography, microprobe, SEM, and EDS analysis of replaced pumice and colloform structures containing both arsenic compositional banding and electrum points to coeval deposition of gold and the volcanic host rocks and, thus, confirms a syngenetic origin for the gold deposits. Early pyrite textures are present in other major deposits of the Carolina slate belt, such as Ridgeway and Barite Hill, and these provide strong evidence for models whereby the sulfide ores formed prior to tectonism. The role of Paleozoic metamorphism was to remobilize and concentrate gold and other minerals in structurally prepared sites. Recognizing the significance of paragenetically early pyrite and gold textures can play an important role in distinguishing sulfide ores that form in volcanic and sedimentary environments from those formed solely by metamorphic processes. Exploration strategies applied to the Carolina slate belt and correlative rocks in the eastern United States in the Avalonian basement will benefit from using syngenetic models for gold mineralization

    Intensification of livestock farming in times of climate change: The challenges of domestic grazing in the drylands of the Argentine Patagonia

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    Livestock grazing modifies and even degrades arid ecosystems, which threatens the sustainability of livestock farming itself. It is essential to learn more about the effects of grazing on vegetation and soil to design strategies to avoid desertification, perhaps the most serious problem faced by drylands. In this paper, we evaluate the changes in the functional traits of the plant community and the biological soil crust induced by the intensification of grazing in Patagonian ecosystems. This description, together with changes in diversity, plant composition, and ecosystem functioning, can help us to understand the mechanisms by which the intensification of sheep grazing could degrade arid ecosystems.; El pastoreo con ganado modifica los ecosistemas áridos y llega incluso a degradarlos, lo que atenta contra la sustentabilidad de la propia actividad ganadera. Resulta clave conocer los efectos del pastoreo sobre la vegetación y el suelo para poder diseñar estrategias que eviten la desertificación, quizá el problema más grave que encaran los ecosistemas áridos. En este artículo, evaluamos los cambios en los rasgos funcionales de la comunidad vegetal y la costra biológica del suelo inducidos por la intensificación del pastoreo en ecosistemas patagónicos. Esta descripción, junto con los cambios en la diversidad, composición y funcionamiento ecosistémico, ayuda a comprender los mecanismos por los que la intensificación del pastoreo ovino podría degradar los ecosistemas áridos.; El pasturatge amb bestiar modifica els ecosistemes àrids i fins i tot arriba a degradar-los, cosa que atempta contra la sostenibilitat de la mateixa activitat ramadera. Resulta clau conèixer els efectes del pasturatge sobre la vegetació i el sòl per a poder dissenyar estratègies que eviten la desertificació, potser el problema més greu que encaren els ecosistemes àrids. En aquest article, avaluem els canvis en els trets funcionals de la comunitat vegetal i la crosta biològica del sòl induïts per la intensificació del pasturatge en ecosistemes patagònics. Aquesta descripció, juntament amb els canvis en la diversitat, composició i funcionament ecosistèmic, ajuda a comprendre els mecanismes pels quals la intensificació del pasturatge oví podria degradar els ecosistemes àrids

    Grazing pressure interacts with aridity to determine the development and diversity of biological soil crusts in Patagonian rangelands

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    Grazing is directly related to land degradation and desertification in global drylands. Grazing impacts on vascular plants, reasonably well‐known, depend on its intensity and are modulated by local aridity conditions. However, we do not know how the interplay of grazing intensity and aridity affect biocrusts, topsoil assemblages dominated by cyanobacteria, lichens, and mosses that provide key ecosystem services in drylands. Here, we determined how grazing affects biomass, total cover, and richness of biocrust structural types across a regional aridity gradient in the Patagonian steppe. On average, grazing by sheep reduced biocrust biomass, total cover and richness of structural types by 55, 90, and 59%, respectively. In general, high grazing pressures had a larger impact on biocrusts than moderate or light grazing pressures. For example, biocrust cover was reduced by 85, 89, and 98% by light, moderate, and high grazing pressures, respectively. Although a slightly different response to grazing was observed under low aridity conditions, these more benign climatic conditions did not compensate for the negative effects of trampling by domestic animals on biocrusts. Nonetheless, estimated biocrust recovery rates under medium aridity conditions were faster than previously thought: it took 24, 18, and 58 years to double biocrust biomass, total cover, and richness of structural types. Sheep cannot be just removed in Patagonian rangelands because the production of meat and wool represents the main local economic activity. But landowners must consider our results to protect the ecosystem functions and services provided by biocrusts for future generations to come.This study was supported by Agencia Nacional de Promoción Científica y Tecnológica (PICT 2014-3026), Universidad de Buenos Aires (20020160100139BA), and Consejo Nacional de Investigaciones Científicas y Técnicas (PIP 2015-0709). F. T. M. is supported by the European Research Council (ERC Grant Agreement nº 647038 [BIODESERT])

    Contribution of Intronic miR-338-3p and Its Hosting Gene AATK to Compensatory β-Cell Mass Expansion.

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    The elucidation of the mechanisms directing β-cell mass regeneration and maintenance is of interest, because the deficit of β-cell mass contributes to diabetes onset and progression. We previously found that the level of the microRNA (miRNA) miR-338-3p is decreased in pancreatic islets from rodent models displaying insulin resistance and compensatory β-cell mass expansion, including pregnant rats, diet-induced obese mice, and db/db mice. Transfection of rat islet cells with oligonucleotides that specifically block miR-338-3p activity increased the fraction of proliferating β-cells in vitro and promoted survival under proapoptotic conditions without affecting the capacity of β-cells to release insulin in response to glucose. Here, we evaluated the role of miR-338-3p in vivo by injecting mice with an adeno-associated viral vector permitting specific sequestration of this miRNA in β-cells. We found that the adeno-associated viral construct increased the fraction of proliferating β-cells confirming the data obtained in vitro. miR-338-3p is generated from an intron of the gene coding for apoptosis-associated tyrosine kinase (AATK). Similarly to miR-338-3p, we found that AATK is down-regulated in rat and human islets and INS832/13 β-cells in the presence of the cAMP-raising agents exendin-4, estradiol, and a G-protein-coupled Receptor 30 agonist. Moreover, AATK expression is reduced in islets of insulin resistant animal models and selective silencing of AATK in INS832/13 cells by RNA interference promoted β-cell proliferation. The results point to a coordinated reduction of miR-338-3p and AATK under insulin resistance conditions and provide evidence for a cooperative action of the miRNA and its hosting gene in compensatory β-cell mass expansion

    Should We Use a Total Score, Two Subscale Scores, or Six Subscale Scores for the Self-Compassion Scale? A Multi-faceted Assessment Beyond Model Fit Indices

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    Datos alojados en : https://osf.io/a98n7/[EN] Objectives The aim of this study was to conduct a multi-faceted assessment of the psychometric properties of the Self Compassion Scale (SCS). In addition to the goodness-of-ft, we aimed to assess the strength and replicability of three factorial solutions, and the quality and efectiveness of the three scoring schemes of the scale (i.e., total scale score, two subscale scores, and six subscale scores). Methods Participants were 1508 Spanish-speaking community-dwelling adults (M =34.94 years, SD=15.02). Data were examined by means of a conjoint strategy using Rasch modeling, non-linear factor analysis, exploratory bifactor analysis, and parallel analysis. A procedure for selecting the optimal set of items that must be used to compute individual’s scores was used.Results The unidimensional solution showed a marginal model ft (RMSR=.089), and both the bifactor two-group and bifactor six-group solutions showed a good ft (RMSR=.043 and .019, respectively). However, only the unidimensional and the bifactor two-factor solutions showed interpretable and replicable factor structures, and high-quality and efective scores to be used for measurement purposes. Subscale scores derived from the six primary factors did not show adequate psychometric properties. It was observed that the information provided by 10 items was redundant and had already been provided by the other 16 items. Conclusions Good model ft is neither sufcient nor necessary to justify the use of a scoring scheme. Goodness-of-ft statistics should be complemented by anassessment of the metric properties of the resulting scores when proposing SCS scoring schemes.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

    Effects of putrescine, cadaverine, spermine, spermidine and β-phenylethylamine on cultured bovine mammary epithelial cells

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    A bovine mammary epithelial cell line (BME-UV1) and three-dimensional collagen primary bovine organoids were used to evaluate the effects of cadaverine, putrescine, spermine, spermidine and β-phenylethylamine on mammary epithelial cells. Each biogenic amine was diluted in several concentrations (0-50 mM in BME-UV1 and 0-4 mM in primary bovine organoids) in the appropriate saline solution for the cell culture considered. In order to determine the activity of each compound tritiated thymidine incorporation was used. At low concentrations, all amines induced cell proliferation in both cultures. In BME-UV1, spermine significantly inhibited cell proliferation (P<0.001), while the other amines inhibited at higher concentrations (50mM). In primary bovine organoids, β−phenylethylamine significantly (P<0.001) inhibited cell proliferation at 4 mM. Organoids cultured in the presence of all amines, except β-phenylethylamine, had stellate projections indicating intense cell proliferation. Proliferation of mammary epithelial cells was stimulated at low concentrations, while at high concentrations it was inhibited. Our results suggested that the effects of each compound on mammary epithelial cells could be related to the compound itself and not to mediating by the bovine amino oxidase, responsible of the formation of toxic metabolites
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