4,755 research outputs found
Maars to calderas. End-members on a spectrum of explosive volcanic depressions
We discuss maar-diatremes and calderas as end-members on a spectrum of negative volcanic landforms (depressions) produced by explosive eruptions (note—we focus on calderas formed during explosive eruptions, recognizing that some caldera types are not related to such activity). The former are dominated by ejection of material during numerous discrete phreatomagmatic explosions, brecciation, and subsidence of diatreme fill, while the latter are dominated by subsidence over a partly evacuated magma chamber during sustained, magmatic volatile-driven discharge. Many examples share characteristics of both, including landforms that are identified as maars but preserve deposits from non-phreatomagmatic explosive activity, and ambiguous structures that appear to be coalesced maars but that also produced sustained explosive eruptions with likely magma reservoir subsidence. A convergence of research directions on issues related to magma-water interaction and shallow reservoir mechanics is an important avenue toward developing a unified picture of the maar-diatreme-caldera spectrum
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
Neutrino telescopes and high-energy cosmic neutrinos
In this review paper, we present the main aspects of high-energy cosmic neutrino astrophysics. We begin by describing the generic expectations for cosmic neutrinos, including the effects of propagation from their sources to the detectors. Then we introduce the operating principles of current neutrino telescopes, and examine the main features (topologies) of the observable events. After a discussion of the main background processes, due to the concomitant presence of secondary particles produced in the terrestrial atmosphere by cosmic rays, we summarize the current status of the observations with astrophysical relevance that have been greatly contributed by IceCube detector. Then, we examine various interpretations of these findings, trying to assess the best candidate sources of cosmic neutrinos. We conclude with a brief perspective on how the field could evolve within a few years
Cosmic Microwave Background Temperature at Galaxy Clusters
We have deduced the cosmic microwave background (CMB) temperature in the Coma
cluster (A1656, ), and in A2163 () from spectral
measurements of the Sunyaev-Zel'dovich (SZ) effect over four passbands at radio
and microwave frequencies. The resulting temperatures at these redshifts are
K and K, respectively. These values confirm the expected
relation , where K is the value
measured by the COBE/FIRAS experiment. Alternative scaling relations that are
conjectured in non-standard cosmologies can be constrained by the data; for
example, if or , then
and (at 95% confidence). We
briefly discuss future prospects for more precise SZ measurements of at
higher redshifts.Comment: 13 pages, 1 figure, ApJL accepted for publicatio
Mars Regolith Simulant Ameliorated by Compost as In Situ Cultivation Substrate Improves Lettuce Growth and Nutritional Aspects
Heavy payloads in future shuttle journeys to Mars present limiting factors, making self-sustenance essential for future colonies. Therefore, in situ resources utilization (ISRU) is the path to successful and feasible space voyages. This research frames the concept of planting leafy vegetables on Mars regolith simulant, ameliorating this substrate’s fertility by the addition of organic residues produced in situ. For this purpose, two butterhead lettuce (Lactuca sativa L. var. capitata) cultivars (green and red Salanova®) were chosen to be cultivated in four dierent mixtures of MMS-1 Mojave Mars simulant:compost (0:100, 30:70, 70:30 and 100:0; v:v) in a phytotron open gas exchange growth chamber. The impact of compost rate on both crop performance and the nutritive value of green- and red-pigmented cultivars was assessed. The 30:70 mixture proved to be optimal in terms of crop performance, photosynthetic activity, intrinsic water use eciency and quality traits of lettuce. In particular, red Salanova® showed the best performance in terms of these quality traits, registering 32% more phenolic content in comparison to 100% simulant. Nonetheless, the 70:30 mixture represents a more realistic scenario when taking into consideration the sustainable use of compost as a limited resource in space farming, while still accepting a slight significant decline in yield and quality in comparison to the 30:70 mixture
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