The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Russell D. Fernald - One of the best experts on this subject based on the ideXlab platform.
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hormonal regulation of social Ascent and temporal patterns of behavior in an african cichlid
Hormones and Behavior, 2019Co-Authors: Beau A Alward, Austin T Hilliard, Ryan A York, Russell D. FernaldAbstract:For many species, social rank determines which individuals perform certain social behaviors and when. Higher ranking or dominant (DOM) individuals maintain status through aggressive interactions and perform courtship behaviors while non-dominant (ND) individuals do not. In some species ND individuals ascend (ASC) in social rank when the opportunity arises. Many important questions related to the mechanistic basis of social Ascent remain to be answered. We probed whether androgen signaling regulates social Ascent in male Astatotilapia burtoni, an African cichlid whose social hierarchy can be readily controlled in the laboratory. As expected, androgen receptor (AR) antagonism abolished reproductive behavior during social Ascent. However, we discovered multiple AR- and status-dependent temporal behavioral patterns that typify social Ascent and dominance. AR antagonism in ASC males increased the time between successive behaviors compared to DOM males. Socially ascending males, independent of AR activation, were more likely than DOM males to follow aggressive displays with another aggressive display. Further analyses revealed differences in the sequencing of aggressive and courtship behaviors, wherein DOM males were more likely than ASC males to follow male-directed aggression with courtship displays. Strikingly, this difference was driven mostly by ASC males taking longer to transition from aggression to courtship, suggesting ASC males can perform certain DOM-typical temporal behavioral patterns. Our results indicate androgen signaling is necessary for social Ascent and hormonal signaling and social experience may shape the full suite of DOM-typical behavioral patterns.
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Behavioral and physiological plasticity: rapid changes during social Ascent in an African cichlid fish.
Hormones and Behavior, 2010Co-Authors: Karen P. Maruska, Russell D. FernaldAbstract:Abstract In many vertebrates, reproduction is regulated by social interactions in which dominant males control access to females and food. Subordinate males that displace dominant individuals must rapidly adopt behavioral and physiological traits of the higher rank to gain reproductive success. To understand the process of phenotypic plasticity during social Ascent, we analyzed the temporal expression pattern of dominance behaviors and circulating androgen levels when socially-suppressed males of an African cichlid fish Astatotilapia burtoni ascended in status. These experiments tested a prediction of the ‘challenge hypothesis’ that, during periods of social instability, male androgen levels are higher than during socially stable times. We found that socially and reproductively suppressed males perform territorial and reproductive behaviors within minutes of an opportunity to ascend in status, and that animals switch from initial expression of territorial behaviors to more reproductive behaviors during territory establishment. Following this rapid response, social stability may be achieved within 1–3 days of social Ascent. Consistent with predictions of the ‘challenge hypothesis’, circulating 11-ketotestosterone (11-KT) levels were elevated within 30 min following social opportunity, coincident with increased aggressive behavior. However, territorial behaviors and serum 11-KT levels were then dissociated by 72 h after social Ascent, suggesting either rapid social stability and/or increased physiological potential for androgen production. This behavioral and physiological plasticity in male A. burtoni suggests that perception of social opportunity triggers a suite of quick changes to facilitate rapid transition towards reproductive success, and reveals important features of social Ascent not previously recognized.
Charles R. Stern - One of the best experts on this subject based on the ideXlab platform.
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Rapid magma Ascent recorded by water diffusion profiles in mantle olivine
Geology, 2006Co-Authors: Sylvie Demouchy, Steven D. Jacobsen, Fabrice Gaillard, Charles R. SternAbstract:Mechanisms and rates of magma Ascent play a critical role in eruption dynamics but remain poorly constrained phenomena. Water, dissolved in mantle minerals as hydrogen and partitioned into the magma during Ascent, may provide clues to quantifying magma Ascent rates prior to eruption. We determined the dehydration profiles in olivine crystals from peridotite mantle xenoliths within the Pali-Aike alkali basalt from Patagonia, Chile. The results demonstrate that the amount of water stored in the uppermost mantle has likely been underestimated due to water loss during transport. Using experimental diffusion data for hydrogen, we estimate that the xenoliths reached the surface from 60–70 km depth in several hours, a surprisingly rapid rise comparable to Ascent rates for kimberlite magmas.
D.a. Doornbos - One of the best experts on this subject based on the ideXlab platform.
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Multicriteria steepest Ascent.
Chemometrics and Intelligent Laboratory Systems, 1994Co-Authors: C.a.a. Duineveld, C.h.p. Bruins, Age K. Smilde, Gk Bolhuis, K. Zuurman, D.a. DoornbosAbstract:Abstract A simple multiresponse steepest Ascent procedure has been developed by combining the standard steepest Ascent method with multicriteria decision making. The steepest Ascent method is one of the older methods in response surface methodology. It can be applied in optimization where the operability region is so large that a very complex function would be needed to fit an empirical function. With steepest Ascent, local designs and local models in a part of the operability region are used to find a direction where the response is improved most. Experiments performed along a line in that direction will reveal the region of interest. There the response may be fitted with a second degree equation. The problem of multiresponse steepest Ascent is that directions of improvement have to be combined into one direction. In general, the directions of improvement indicated by the individual responses are different and they may even be opposite. In this paper, steepest Ascent has been adapted to the use of more responses by combination of the directions of steepest Ascent to a simultaneous direction of interest. The combination is made by consideration of the obtainable improvements of the responses in the response space. These improvements can be calculated from the centre point (of the local design) response values and the response values at a fixed distance of the centre point. As an example, the method has been applied to a tablet optimization. This optimization problem had two responses and two independent variables.
Malcolm J. Rutherford - One of the best experts on this subject based on the ideXlab platform.
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Magma Ascent Rates
Reviews in Mineralogy and Geochemistry, 2008Co-Authors: Malcolm J. RutherfordAbstract:Volcanoes can erupt explosively, generating high columns of ash and occasional pyroclastic flows, or they can erupt slowly forming lava flows and domes. This variation reflects significant differences in mass eruption rate (e.g., Wilson et al. 1980). Mass eruption rates in turn are controlled by the rates of magma Ascent through the volcanic conduit, and the conduit size. The magma Ascent rate itself is a function of the pressure in the magma storage region, the physical properties of the magma, such as its density, viscosity and crystallinity, and the resistance to flow in the conduit that connects the magma storage zone to the surface (Papale and Dobran 1994; Mastin and Ghiorso 2001; Pinkerton et al. 2002; Sparks et al. 2006). A number of important characteristics of volcanic eruptions are affected or controlled by the rate at which magma ascends from depth. For example, the bubble content (i.e., vesicularity) and the degree of crystallization that develop in the melt phase can be significantly different in rapidly vs. slowly ascended magma. In fact, the inability of rapidly ascending magma to effectively lose exsolved gas may be one factor causing an eruption to change from effusive to explosive behavior, as recently documented for the Soufriere Hills eruption on Montserrat in the West Indies (Sparks et al. 1998). Therefore, in order to better understand the processes involved and the changes that occur in volcanic eruptions, it is important to quantify the rates at which different magmas rise to the surface. The fact that the rate of magma Ascent controls a number of reactions that occur in volatile-rich magmas suggests several ways to study magma Ascent rates using reaction data and theoretical flow models. One reaction that is a direct result of magma Ascent is the exsolution of volatiles from the melt …
Morgan, Jason P. - One of the best experts on this subject based on the ideXlab platform.
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Earth's deepest earthquake swarms track fluid Ascent beneath nAscent arc volcanoes
Elsevier, 2019Co-Authors: White, Lloyd T., Waldhauser Felix, Hejrani Babak, Thompson, David A., Tanner Dominique, Macpherson, Colin G., Tkalcic Hrvoje, Rawlinson Nicholas, Lister, Gordon S., Morgan, Jason P.Abstract:Most of the world's explosive volcanoes are located in volcanic arcs, formed by fluid-fluxed melting of upper mantle rocks. The fluids that facilitate melting are released from subducted tectonic plates as they sink into the mantle. Yet, we have sparse knowledge of the migration pathways of melts through the upper mantle (i.e., between the surface of the subducted plate and arc volcanoes). We are also uncertain of the time required for this migration to occur. Here, we show evidence of two earthquake swarms that occur in the upper mantle beneath the Mariana and Izu-Bonin arc systems. The best-resolved swarm occurs beneath the Mariana arc, where the earthquakes define a sub-vertical pipe-like structure with a diameter of ∼50 km and occurs between depths of ∼10–250 km. To test the robustness of depth locations, we used a fully non-linear grid search algorithm, double-difference relocation, as well as an analysis of pP-P arrival times and depth sensitive phases. In addition, we calculated centroid moment tensor solutions using a 3D Earth model to understand the mechanism of failure within the swarms. These data demonstrate that the sub-vertical earthquake swarm occurs within the upper mantle between the subducted slab and the overriding volcanic arc, with seismicity concentrated within discrete day- to month-long swarms of activity over a single two-year period. The Izu-Bonin example shares a similar sub-vertical pipe-like geometry with seismic activity bracketed within a two-year period. We infer that these rare earthquake swarms record the Ascent of hydrous melt and/or fluid, from dehydration of the subducting plate. This implies that hydrous minerals within subducted slabs continue to dehydrate to depths of at least 200–250 km. Also, the short duration of earthquake swarms implies that fluids/melts can be rapidly transported through the sub-arc mantle at rates in the order of km/hr. This is consistent with rapid melt Ascent rates inferred from geospeedometry and experimental petrology and is reminiscent of patterns seen during episodic tremor and slip events
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Earth's deepest earthquake swarms track fluid Ascent beneath nAscent arc volcanoes
'Elsevier BV', 2019Co-Authors: White Lloyd, Rawlinson Nick, Lister Gordon, Waldhauser Felix, Hejrani Babak, Thompson, David A., Tanner Dominique, Macpherson, Colin G., Tkalcic Hrvoje, Morgan, Jason P.Abstract:Most of the world's explosive volcanoes are located in volcanic arcs, formed by fluid-fluxed melting of upper mantle rocks. The fluids that facilitate melting are released from subducted tectonic plates as they sink into the mantle. Yet, we have sparse knowledge of the migration pathways of melts through the upper mantle (i.e., between the surface of the subducted plate and arc volcanoes). We are also uncertain of the time required for this migration to occur. Here, we show evidence of two earthquake swarms that occur in the upper mantle beneath the Mariana and Izu-Bonin arc systems. The best-resolved swarm occurs beneath the Mariana arc, where the earthquakes define a sub-vertical pipe-like structure with a diameter of ∼50 km and occurs between depths of ∼10–250 km. To test the robustness of depth locations, we used a fully non-linear grid search algorithm, double-difference relocation, as well as an analysis of pP-P arrival times and depth sensitive phases. In addition, we calculated centroid moment tensor solutions using a 3D Earth model to understand the mechanism of failure within the swarms. These data demonstrate that the sub-vertical earthquake swarm occurs within the upper mantle between the subducted slab and the overriding volcanic arc, with seismicity concentrated within discrete day- to month-long swarms of activity over a single two-year period. The Izu-Bonin example shares a similar sub-vertical pipe-like geometry with seismic activity bracketed within a two-year period. We infer that these rare earthquake swarms record the Ascent of hydrous melt and/or fluid, from dehydration of the subducting plate. This implies that hydrous minerals within subducted slabs continue to dehydrate to depths of at least 200–250 km. Also, the short duration of earthquake swarms implies that fluids/melts can be rapidly transported through the sub-arc mantle at rates in the order of km/hr. This is consistent with rapid melt Ascent rates inferred from geospeedometry and experimental petrology and is reminiscent of patterns seen during episodic tremor and slip events.L.T.W, N.R. and G.S.L thank several mineral exploration companies and an Australian Research Council Linkage Project (ARC LP130100134) for funding that supported this work. L.T.W. thanks a start-up grant from the University of Wollongong and the Faculty of Science, Medicine and Health for supporting this research. J.P.M. thanks a Wolfson Research Merit Award from the Royal Society for support. The research reported here was further supported by the Satellites, Seismometers and Mass Spectrometers initiative, a joint venture between the Structure Tectonics team and the Geodesy and Geodynamics team, in the Earth Dynamics Group, and the Seismology and Mathematical Geophysics Group at the Research School of Earth Sciences, ANU. The work also benefited from access to several software suites (eQuakes, Paradigm's GoCAD and PDF3D ReportGen) as well as several anonymous reviewers. We would also like to thank Huw Davies, Brad Hacker and Simon Klemperer for comments on earlier iterations of this paper
