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Concept: The Ascent

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Timescales of magma ascent in conduit models are typically assumed to be much longer than crystallization and gas exsolution for basaltic eruptions. However, it is now recognized that basaltic magmas may rise fast enough for disequilibrium processes to play a key role on the ascent dynamics. The quantification of the characteristic times for crystallization and exsolution processes are fundamental to our understanding of such disequilibria and ascent dynamics. Here we use observations from Mount Etna’s 2001 eruption and a magma ascent model to constrain timescales for crystallization and exsolution processes. Our results show that plagioclase reaches equilibrium in 1-2 h, whereas ascent times were <1 h. Using these new constraints on disequilibrium plagioclase crystallization we also reproduce observed crystal abundances for different basaltic eruptions. The strong relation between magma ascent rate and disequilibrium crystallization and exsolution plays a key role in controlling eruption dynamics in basaltic volcanism.

Concepts: Scientific method, Igneous rock, Volcano, Magma, Basalt, Mount Etna, The Ascent, Andesite

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Increasing industrialization, urbanization, and a failure of many world leaders to appreciate the consequences of climate change are deleteriously impacting quality of life as well as diminishing the prospects for long term survival. Economic competitiveness and corporate profitability often pre-empt environmental concerns. The calving of an iceberg in Antarctica and the hurricane activity in the Caribbean during 2017 are unfortunate illustrations of the continuing escalation of environmental issues. We provide historical and current evidence for the importance of Nature Exposure (NE) and introduce the continuum Nature Exposure Sufficiency (NES) and Insufficiency (NEI). Insufficiency includes impoverished environments (e.g., slums and prisons) where nature exposure is very limited. Nature Exposure Sufficiency (NES) is an optimal amount of exposure to nature where many benefits such as reinvigoration can be obtained by everyone. NES also has several benefits for individuals with various health conditions such as arthritis, dementia, or depression. The benefits of NE are not just derivable from parks, forests, and other natural settings. Interiors of buildings and homes can be enhanced with plants and even pictures or objects from nature. Additionally, there is abundant evidence indicating that virtual and artificial environments depicting nature can provide substantial NE and therefore contribute to general wellbeing. Besides the difficulty in achieving cooperation amongst nations, corporations, and other collectives in developing and implementing long range plans to deal with climate change, there is also sometimes an aversion at the individual level whereby people are unwilling to experience nature due to insects and other discomforts. Such individuals are often averse to supplanting the comforts of home, even temporarily, with inadequate facilities that are seemingly less pleasant than their typical dwellings. We propose using the term Nature Exposure Aversion (NEA) to describe such behavior and propose that the aversion is largely due to conditioning. Such behavior may be addressed through desensitization in virtual environments which in turn may contribute to an endorsement of the view that climate change is occurring and must be dealt with. The issues of Nature Exposure Sufficiency and Insufficiency are intertwined with the sustainability of the planet and future planning and efforts to deal with the environment. If the outcome is unfavorable, the descent of civilization will be more rapid than the ascent.

Concepts: Environment, Natural environment, Weather, Climate change, Term, Environmentalism, Environmental science, The Ascent

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This study examined the role of route previewing strategies on climbing fluency and on exploratory movements of the limbs, in order to understand whether previewing helps people to perceive and to realize affordances. Eight inexperienced and ten experienced climbers previewed a 10 m high route of 5b difficulty on French scale, then climbed it with a top-rope as fluently as possible. Gaze behavior was collected from an eye tracking system during the preview and allowed us to determine the number of times they scanned the route, and which of four route previewing strategies (fragmentary, ascending, zigzagging, and sequence-of-blocks) they used. Five inertial measurement units (IMU) (3D accelerometer, 3D gyroscope, 3D magnetometer) were attached to the hip, both feet, and forearms to analyze the vertical acceleration and direction of each limb and hip during the ascent. We were able to detect movement and immobility phases of each IMU using segmentation and classification processes. Depending on whether the limbs and/or hip were moving, five states of behavior were detected: immobility, postural regulation, hold exploration, hold change, and hold traction. Using cluster analysis we identified four clusters of gaze behavior during route previewing depending on route preview duration, number of scan paths, fixations duration, ascending, zigzagging, and sequence-of-blocks strategies. The number of scan paths was positively correlated with relative duration of exploration and negatively correlated with relative duration of hold changes during the ascent. Additionally, a high relative duration of sequence-of-blocks strategy and zigzagging strategy were associated with a high relative duration of immobility during the ascent. Route previewing might help to pick up functional information about reachable, graspable, and usable holds, in order to chain movements together and to find the route. In other words, route previewing might contribute to perceiving and realizing nested affordances.

Concepts: Cluster analysis, Perception, Relative humidity, Strategy, Strategy pattern, Climbing, Hold, The Ascent

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Within the volcanological community there is a growing awareness that many large- to small-scale, point-source eruptive events can be fed by multiple melt bodies rather than from a single magma reservoir. In this study, glass shard major- and trace-element compositions were determined from tephra systematically sampled from the outset of the Puyehue-Cordón Caulle (PCC) eruption (~1 km(3)) in southern Chile which commenced on June 4(th), 2011. Three distinct but cogenetic magma bodies were simultaneously tapped during the paroxysmal phase of this eruption. These are readily identified by clear compositional gaps in CaO, and by Sr/Zr and Sr/Y ratios, resulting from dominantly plagioclase extraction at slightly different pressures, with incompatible elements controlled by zircon crystallisation. Our results clearly demonstrate the utility of glass shard major- and trace-element data in defining the contribution of multiple magma bodies to an explosive eruption. The complex spatial association of the PCC fissure zone with the Liquiñe-Ofqui Fault zone was likely an influential factor that impeded the ascent of the parent magma and allowed the formation of discrete melt bodies within the sub-volcanic system that continued to independently fractionate.

Concepts: Glass, Chile, Clear, Tetrahydrogestrinone, Composition, Clearing, Fault, The Ascent

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We can propound a thermo-mechanical understanding of the ascent of sap to the top of tall trees thanks to a comparison between experiments associated with the cohesion-tension theory and the disjoining pressure concept for liquid thin-films. When a segment of xylem is tight-filled with crude sap, the liquid pressure can be negative although the pressure in embolized vessels remains positive. Examples are given that illustrate how embolized vessels can be refilled and why the ascent of sap is possible even in the tallest trees avoiding the problem due to cavitation. However, the maximum height of trees is limited by the stability domain of liquid thin-films.

Concepts: Human height, Gas, Plant physiology, Xylem, The Ascent

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ImportanceIt is well known that altitude ascent with intravitreal gas can cause expansion of gas and intraocular pressure (IOP) elevation. According to Boyle’s law, the gas bubble will not expand unless a higher altitude than the gas insertion site has been reached. We report four cases in which intravitreal gas was injected at an altitude of 790 m (Jerusalem). All four cases developed high IOP even though they did not reach a higher altitude in their post-operative period.ObservationsA report of four patients following vitrectomy with 12% mixture of perfluoropropane and air are presented. All four patients arrived with ocular pain following the ascent by car of 765-1100 m to Jerusalem where the vitrectomy and gas insertion was conducted. Upon examination, all four patients had high IOP (30-55 mm Hg). IOP was well controlled with IOP-lowering medications. None of the patients suffered from long-term complications.Conclusions and RelevanceCaution should be taken with altitude changes in patients with intravitreal gas even if there was no ascent from the altitude in which the vitrectomy was performed.Eye advance online publication, 2 May 2014; doi:10.1038/eye.2014.83.

Concepts: Intraocular pressure, Pressure, Altitude, Ideal gas law, Octafluoropropane, Boyle's law, Combined gas law, The Ascent