Search results for "105"
showing 10 items of 9364 documents
Experimental Constraints on the Deep Magma Feeding System at StromboliVolcano, Italy
2009
International audience; New experiments have been performed on a high-K basalt (PST-9) from Stromboli volcano, Italy, to constrain the physical conditions of golden pumice magmas at their storage level and discuss their petrogenesis. Fluid-present, H2O- and CO2-bearing, near-liquidus experiments were performed at 11508C between 100 and 400MPa and under oxidizing conditions. Glasses were analyzed by Fourier transform IR spectroscopy and their H2O and CO2 concentrations compared with those in glass inclusions.Most glass inclusions cluster near the 200MPa isobar, suggesting entrapment at a depth of ~8 km. Golden pumice magmas have viscosities of 7.9 Pa s and densities of 2.48-2.57 g/cm3. Compo…
Ultra-high temperature metamorphism recorded in Fe-rich olivine-bearing migmatite from the Khondalite Belt, North China Craton
2018
International audience; We document the first occurrence of Fe‐rich olivine‐bearing migmatitic metapelite in the Khondalite Belt, North China Craton. Petrological analyses revealed two exotic assemblages of orthopyroxene+spinel+olivine and orthopyroxene+spinel+cordierite. Phase relation modelling suggests that these assemblages are diagnostic of ultra‐high temperature (UHT) metamorphism in the Fe‐rich system, with temperatures from 1,000 to 1,050°C at 0.6 GPa. U–Th–Pb SIMS analyses on zircon reveal a similar age of c. 1.92 Ga for the olivine‐bearing migmatite and an adjacent gabbronoritic intrusion that is therefore identified as the heat source for the UHT metamorphism. These results, coup…
Alteration-Induced Volcano Instability at La Soufrière de Guadeloupe (Eastern Caribbean)
2021
International audience; Volcanoes are unstable structures that deform laterally and frequently experience mass wasting events. Hydrothermal alteration is often invoked as a mechanism that contributes significantly to volcano instability. We present a study that combines laboratory experiments, geophysical data, and large-scale numerical modeling to better understand the influence of alteration on volcano stability, using La Soufrière de Guadeloupe (Eastern Caribbean) as a case study. Laboratory experiments on variably altered (advanced argillic alteration) blocks show that uniaxial compressive strength, Young's modulus, and cohesion decrease as a function of increasing alteration, but that …
More nature in the city
2020
According to projects and practices that the Italian botanists and ecologists are carrying out for bringing “more nature in the city”, new insights for a factual integration between ecological perspectives and more consolidated aesthetic and agronomic approaches to the sustainable planning and management of urban green areas are provided.
Pathways for the amplification of agroecology in African sustainable urban agriculture
2020
A growing awareness that highly intensified agricultural systems have made a substantial worldwide contribution to the worsening of the resilience capacity of natural ecosystems has, over the last twenty years, brought general attention to agroecological management models. This aspect is even more evident in industrial agriculture, which is based on the use of multiple chemical products derived from non-natural synthesis. In more developed countries, a new idea of ecology linked to agricultural production has been increasingly developed and, for this reason, there has been a greater diffusion of differentiated agricultural models taking into consideration the environmental impact of product…
Aceptación del pago móvil en España: análisis de la conveniencia y la usabilidad en el contexto de una batalla generacional
2017
Entender la aceptación y el uso de una nueva tecnología constituye una de las corrientes más maduras y fructíferas de investigación dentro de los sistemas de información. Contar con un modelo que maximice el poder explicativo sin perder de vista el contexto de utilización y las características de los usuarios, se ha transformado en un imperativo. El propósito central de la investigación propuesta consiste en presentar y contrastar un modelo holístico de síntesis de aceptación voluntaria de una tecnología, por parte de un consumidor individual. Este modelo integrará distintas perspectivas, aplicadas a la adopción del servicio de pago móvil. Asimismo, se analizará el impacto de la brecha gene…
SST Comparison of AVHRR and MODIS Time Series in the Western Mediterranean Sea
2020
La temperatura de la superficie del mar (SST) es un parámetro clave para comprender los procesos atmosféricos y oceánicos. Desde finales de la década de 1980, las imágenes de satélite infrarrojas se han utilizado para complementar los registros in situ para estudiar la variabilidad temporal y espacial de la SST. El radiómetro avanzado de muy alta resolución (AVHRR) del satélite de la Administración Nacional Oceánica y Atmosférica (NOAA) fue el primer sensor utilizado con éxito para calcular la SST después del desarrollo y validación del algoritmo de corrección atmosférica conocido como 'ventana dividida'. Más recientemente, el espectrorradiómetro de imágenes de resolución MODERADA (MODIS) a…
Assessment of Microstressors in Adults: Questionnaire Development and Ecological Validation of the Mainz Inventory of Microstressors
2020
Background Many existing scales for microstressor assessment do not differentiate between objective (ie, observable) stressor events and stressful cognitions or concerns. They often mix items assessing objective stressor events with items measuring other aspects of stress, such as perceived stressor severity, the evoked stress reaction, or further consequences on health, which may result in spurious associations in studies that include other questionnaires that measure such constructs. Most scales were developed several decades ago; therefore, modern life stressors may not be represented. Ecological momentary assessment (EMA) allows for sampling of current behaviors and experiences in real…
Toward a Dimensional Assessment of Externalizing Disorders in Children : Reliability and Validity of a Semi-Structured Parent Interview
2020
Objective: This study assesses the reliability and validity of the DSM-5-based, semi-structured Clinical Parent Interview for Externalizing Disorders in Children and Adolescents (ILF-EXTERNAL). Method: Participant data were drawn from the ongoing ESCAschool intervention study. The ILF-EXTERNAL was evaluated in a clinical sample of 474 children and adolescents (aged 6−12 years, 92 females) with symptoms of attention-deficit/hyperactivity disorder (ADHD). To obtain interrater reliability, the one-way random-effects, absolute agreement models of the intraclass correlation (ICC) for single ICC(1,1) and average measurements ICC(1,3) were computed between the interviewers and two independent rate…
Assessing Statistical Anxiety Among Online and Traditional Students
2019
The purpose of this study was to determine whether scores on the Statistical Anxiety Scale (SAS) manifest in the same way for students in online and traditional statistics courses. Tests of measurement invariance indicated that invariance of the two-factor model of the SAS held at every level. Therefore, we compared the statistical anxiety of online and traditional students. Results indicated that online and traditional statistics students reported comparable levels of anxiety with slightly less anxiety in terms of seeking help for traditional students. We concluded that online instruction is a viable form of statistics education at least for undergraduate students enrolled in the social sc…