4,052 research outputs found
Corrigendum. Maars to calderas: end-members on a spectrum of explosive volcanic depressions
A corrigendum on
Maars to calderas: end-members on a spectrum of explosive volcanic depressions
by Palladino, D. M., Valentine, G. A., Sottili, G., and Taddeucci, J. (2015). Front. Earth Sci. 3:36.
doi: 10.3389/feart.2015.00036
Reason for Corrigendum:
In the original article (Palladino et al., 2015), there was an error in Figure 1. The vertical axis
of the qualitative plot reported erroneously “ratio of juvenile to lithic materials in deposits outside
of depression”. The correct wording is as follows: “ratio of juvenile to total (i.e., juvenile+lithic)
materials in deposits outside of depression”. In fact, as it was reported correctly in the text, the
amount of juvenilematerial (i.e., scoria or pumice) deposited ouside the different types of explosive
volcanic depressions increases from zero (i.e., no juvenile, all lithic products), as is the case of
hydrothermal (phreatic) explosion craters, to become largely dominant over the lithic component
in the case of ash flow deposits associated with large overpressure collapse calderas. The corrected Figure 1 appears below. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way
Source- vs topographic-forcing in pyroclastic currents. the case of the Orvieto-Bagnoregio Ignimbrite, Vulsini, central Italy
The main pyroclastic flow unit of the Orvieto-Bagnoregio Ignimbrite (Vulsini, central Italy) provides a striking example of increasing thickness with distance from the vent, accompanied by opposite size-distance trends for lithic and juvenile clasts. Lithic clasts show normal lateral grading, while dense (1120-1400 kg/m3) scoria clasts show inverse lateral grading. The latter trends are attributed to the opposite density contrast with respect to the flow medium of gas and fine particles and put a constraint to the minimum density of the transporting flow. Thus, the study example approaches the high concentration, non-turbulent end-member of pyroclastic currents. By applying the topological aspect ratio approach, we infer a forced behavior of the parent flow in proximal to intermediate settings, due to sustained feeding with high mass discharge rate at source. In distal settings, the source-forced regime was enhanced by topographic forcing due to channeling along radial topographic lows, thus resulting in increasing bulk density and runout of the current. By analogy with the mobility of dry debris flows, the sliding component of transport prevailed from proximal to intermediate settings, accounting for the prevailing tendency of the pyroclastic current to transport than to deposit, thus forming a relatively thin deposit with normal lateral grading of lithics. The spreading component dominated toward the distal settings, resulting in increasing pyroclast accumulation (up to tens of meters of thickness) and delayed deposition of coarsest scoria clasts as far as the final runout
Thermal Comfort Evaluation Within Non-residential Environments: Development of Artificial Neural Network by Using the Adaptive Approach Data☆
Abstract A new algorithm for the PMV calculation was developed using Artificial Neural Networks. Several experimental investigations were carried out in two classrooms using both Fanger static model and adaptive approaches for the PMV evaluation. The Artificial Neural Network was trained considering a few input parameters; specifically for the network development only the air temperature and relative humidity were considered as experimental data. This algorithm allows to correlate the thermal sensation to both indoor and outdoor factors and it is a useful tool for predicting the PMV index, replacing the traditional methods with less time and cost demanding
CHANTI: a Fast and Efficient Charged Particle Veto Detector for the NA62 Experiment at CERN
The design, construction and test of a charged particle detector made of
scintillation counters read by Silicon Photomultipliers (SiPM) is described.
The detector, which operates in vacuum and is used as a veto counter in the
NA62 experiment at CERN, has a single channel time resolution of 1.14 ns, a
spatial resolution of ~2.5 mm and an efficiency very close to 1 for penetrating
charged particles
Validation of a multi-scale simulation strategy based on the Pointwise Strain Superposition Method
This paper details the experimental validation of a multi-scale simulation strategy that we developed for predicting the stresses and distortions induced by Powder Bed Fusion processes. The strategy comprises a meso-scale model, a macro-scale model, and a scaling method named Pointwise Strain Superposition. The first model evaluates the temperature, stress, and strain fields produced by a single scan line. The scaling method transfers the meso-scale results to the macro-scale model, which is then able to simulate the entire manufacturing process with a reasonable computational cost. The simulation strategy was validated by comparing its results with the stresses and distortions measured on several specimens made of selective laser melted Inconel 718. Stresses were measured through the blind hole drilling method on a cylindrical specimen printed with two different scanning strategies, while distortions were measured on a hollow cylinder and on a cantilever-shaped specimen after removing its supports. In both cases, the simulation showed first- or higher-order accuracy despite the significant uncertainties regarding the input parameters and material properties. This robustness, coupled with its computational efficiency, leads us to believe that our simulation strategy could enhance the process optimization and provide a better understanding of the underlying physical phenomena along with their effects on the manufactured parts
Genotypic Characterization of Non-O157 Shiga Toxin–Producing Escherichia coli in Beef Abattoirs of Argentina
The non-O157 Shiga toxin-producing Escherichia coli (STEC) contamination in carcasses and feces of 811 bovines in nine beef abattoirs from Argentina was analyzed during a period of 17 months. The feces of 181 (22.3%) bovines were positive for non-O157 STEC, while 73 (9.0%) of the carcasses showed non-O157 STEC contamination. Non-O157 STEC strains isolated from feces (227) and carcasses (80) were characterized. The main serotypes identified were O178:H19, O8:H19, O130:H11, and O113:H21, all of which have produced sporadic cases of hemolytic-uremic syndrome in Argentina and worldwide. Twenty-two (7.2%) strains carried a fully virulent stx/eae/ehxA genotype. Among them, strains of serotypes O103:[H2], O145:NM, and O111:NM represented 4.8% of the isolates. XbaI pulsed-field gel electrophoresis pattern analysis showed 234 different patterns, with 76 strains grouped in 30 clusters. Nine of the clusters grouped strains isolated from feces and from carcasses of the same or different bovines in a lot, while three clusters were comprised of strains distributed in more than one abattoir. Patterns AREXSX01.0157, AREXBX01.0015, and AREXPX01.0013 were identified as 100% compatible with the patterns of one strain isolated from a hemolytic-uremic syndrome case and two strains previously isolated from beef medallions, included in the Argentine PulseNet Database. In this survey, 4.8% (39 of 811) of the bovine carcasses appeared to be contaminated with non- O157 STEC strains potentially capable of producing sporadic human disease, and a lower proportion (0.25%) with strains able to produce outbreaks of severe disease.Fil: Masana, Marcelo. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; ArgentinaFil: D´Astek, B. A.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Palladino, Pablo Martín. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; ArgentinaFil: Galli, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas; ArgentinaFil: del Castillo, Lourdes Leonor. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; ArgentinaFil: Carbonari, Claudia Carolina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas; ArgentinaFil: Leotta, Gerardo Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas; ArgentinaFil: Vilacoba, Elisabet. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas; ArgentinaFil: Irino, K.. Instituto Adolfo Lutz. Seção de Bacteriologia; BrasilFil: Rivas, M.. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas; Argentin
Qualitative methods II: minding the gap
Copyright © 2008 SAGE Publications. Author's draft version; post-print. Final version published by Sage available on Sage Journals Online http://online.sagepub.com/In our last review we drew together work
exploring interactions between the performativity
of research practices and the spaces
of qualitative research (Davies and Dwyer,
2007). In this, we focus on the oscillating political
subjectivities mobilized in research by
human geographers and other qualitative
researchers
High-speed imaging of Strombolian explosions: The ejection velocity of pyroclasts
Explosive volcanic eruptions are defined as the violent ejection of gas and hot fragments from a vent in the Earth's crust. Knowledge of ejection velocity is crucial for understanding and modeling relevant physical processes of an eruption, and yet direct measurements are still a difficult task with largely variable results. Here we apply pioneering high-speed imaging to measure the ejection velocity of pyroclasts from Strombolian explosive eruptions with an unparalleled temporal resolution. Measured supersonic velocities, up to 405 m/s, are twice higher than previously reported for such eruptions. Individual Strombolian explosions include multiple, sub-second-lasting ejection pulses characterized by an exponential decay of velocity. When fitted with an empirical model from shock-tube experiments literature, this decay allows constraining the length of the pressurized gas pockets responsible for the ejection pulses. These results directly impact eruption modeling and related hazard assessment, as well as the interpretation of geophysical signals from monitoring networks
Major explosive activity in the Monti Sabatini Volcanic District(central Italy) over the 800-390ka interval: Geochronological-geochemical overview and tephrostratigraphic implications
A review of the existing chronological, stratigraphic and chemo-petrologic data of the major eruptive units from the early phase of activity (800-390ka) in the Monti Sabatini Volcanic District (MSVD), belonging to the ultra-potassic magmatic region of central Italy, is presented along with new radioisotopic age determinations and geochemical analyses. Through the combined use of electron microprobe glass compositions, selected trace-element compositions, and single-crystal 40Ar/39Ar age determinations, we provide a new chrono- and chemo-stratigraphic classification of the products emplaced in the 800-390ka time interval. Besides giving insights on the petrologic evolution of the Roman Comagmatic Region, the large dataset provides fundamental information that is applicable to tephrostratigraphic studies in the wide region encompassing the Tyrrhenian Sea margin to the Adriatic Sea basin. Distal tephras from this volcanic activity also act as important geochronologic markers for the coastal sedimentary successions deposited in response to glacio-eustatic fluctuations, as well as for successions in the Quaternary tectonic basins of the Central and Southern Apennines. An innovative approach based on the use of discrimination diagrams of Zr/Y vs Nb/Y ratios for fingerprinting altered volcanic rocks - recently developed and successfully employed in archaeometric studies - is here combined to the glass compositions for classifying the MSVD deposits and tested on two distal tephra layers, showing its potentiality for tephrostratigraphic correlation. © 2014 Elsevier Ltd
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