Melt-rock reaction and melt migration in the MORB mantle through combined natural and experimental studies

Impact ◽  
2017 ◽  
Vol 2017 (7) ◽  
pp. 29-31
Author(s):  
Elisabetta Rampone
Author(s):  
Tracy Rushmer

ABSTRACT:The rheological and chemical behaviour of the lower crust during anatexis has been a major focus of geological investigations for many years. Modern studies of crustal evolution require significant knowledge, not only of the potential source regions for granites, but also of the transport paths and emplacement mechanisms operating during granite genesis. We have gained significant insights into the segregation and transport of granitoid melts from the results of experimental studies on rock behaviour during partial melting. Experiments performed on crustal rock cores under both hydrostatic conditions and during deformation have led, in part, to two conclusions. (1) The interfacial energy controlling melt distribution is anisotropic and, as a result, the textures deviate significantly from those predicted for ideal systems—planar solid-melt interfaces are developed in addition to triple junction melt pockets. The ideal dihedral angle model for melt distribution cannot be used as a constraint to predict melt migration in the lower crust. (2) The ‘critical melt fraction’ model, which requires viscous, granitic melt to remain in the source until melt fractions reach >25 vol%, is not a reliable model for melt segregation. The most recent experimental results on crustal rock cores which have helped advance our understanding of melt segregation processes have shown that melt segregation is controlled by several variables, including the depth of melting, the type of reaction and the volume change associated with that reaction. Larger scale processes such as tectonic environment determine the rate at which the lower crust heats and deforms, thus the tectonic setting controls the melt fraction at which segregation takes place, in addition to the pressure and temperature of the potential melting reactions. Melt migration therefore can occur at a variety of different melt fractions depending on the tectonic environment; these results have significant implications for the predicted geochemistry of the magmas themselves.


Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.


Author(s):  
Ina Grau ◽  
Jörg Doll

Abstract. Employing one correlational and two experimental studies, this paper examines the influence of attachment styles (secure, anxious, avoidant) on a person’s experience of equity in intimate relationships. While one experimental study employed a priming technique to stimulate the different attachment styles, the other involved vignettes describing fictitious characters with typical attachment styles. As the specific hypotheses about the single equity components have been developed on the basis of the attachment theory, the equity ratio itself and the four equity components (own outcome, own input, partner’s outcome, partner’s input) are analyzed as dependent variables. While partners with a secure attachment style tend to describe their relationship as equitable (i.e., they give and take extensively), partners who feel anxious about their relationship generally see themselves as being in an inequitable, disadvantaged position (i.e., they receive little from their partner). The hypothesis that avoidant partners would feel advantaged as they were less committed was only supported by the correlational study. Against expectations, the results of both experiments indicate that avoidant partners generally see themselves (or see avoidant vignettes) as being treated equitably, but that there is less emotional exchange than is the case with secure partners. Avoidant partners give and take less than secure ones.


Author(s):  
Anne Andronikof

Based on an analysis of John Exner’s peer-reviewed published work from 1959 to 2007, plus a brief comment for an editorial in Rorschachiana, the author draws a comprehensive picture of the scientific work of this outstanding personality. The article is divided into three sections: (1) the experimental studies on the Rorschach, (2) the clinical studies using the Rorschach, and (3) Exner’s “testament,” which we draw from the last paper he saw published before his death (Exner, 2001/2002). The experimental studies were aimed at better understanding the nature of the test, in particular the respective roles of perception and projection in the response process. These fundamental studies led to a deeper understanding of the complex mechanisms involved in the Rorschach responses and introduced some hypotheses about the intentions of the author of the test. The latter were subsequently confirmed by the preparatory sketches and documents of Hermann Rorschach, which today can be seen at the H. Rorschach Archives and Museum in Bern (Switzerland). Exner’s research has evidenced the notion that the Rorschach is a perceptive-cognitive-projective test.


2013 ◽  
Vol 44 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Mauro Bertolotti ◽  
Patrizia Catellani ◽  
Karen M. Douglas ◽  
Robbie M. Sutton

In two experimental studies (conducted in Britain and Italy), participants read about a politician answering to leadership- versus morality-related allegations using either downward counterfactuals (“things could have been worse, if ...”) or upward counterfactuals (“things could have been better, if ...”). Downward messages increased the perception of the politician’s leadership, while both downward and upward messages increased morality perception. Political sophistication moderated the effect of message direction, with downward messages increasing perceived morality in low sophisticates and upward messages increasing perceived morality in high sophisticates. In the latter group, the acknowledgment of an intent to take responsibility mediated morality judgment. Results were consistent across different countries, highlighting previously unexplored effects of communication on the perception of the “Big Two” dimensions.


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