The field and microstructural signatures of deformation‐assisted melt transfer: Insights from magmatic arc lower crust, New Zealand

Melt must transfer through the lower crust, yet the field signatures and mechanisms involved in such transfer zones (excluding dykes) are still poorly understood. We report field and microstructural evidence of a deformation‐assisted melt transfer zone that developed in the lower crustal magmatic arc environment of Fiordland, New Zealand. A 30–40 m wide hornblende‐rich body comprising hornblende ± clinozoisite and/or garnet exhibits 'igneous‐like' features and is hosted within a metamorphic, two‐pyroxene–pargasite gabbroic gneiss (GG). Previous studies have interpreted the hornblende‐rich body as an igneous cumulate or a mass transfer zone. We present field and microstructural characteristics supporting the later and indicating the body has formed by deformation‐assisted, channelized, reactive porous melt flow. The host granulite facies GG contains distinctive rectilinear dykes and garnet reaction zones (GRZ) from earlier in the geological history; these form important reaction and strain markers. Field observations show that the mineral assemblages and microstructures of the GG and GRZ are progressively modified with proximity to the hornblende‐rich body. At the same time, GRZ bend systematically into the hornblende‐rich body on each side of the unit, showing apparent sinistral shearing. Within the hornblende‐rich body itself, microstructures and electron back‐scatter diffraction mapping show evidence of the former presence of melt including observations consistent with melt crystallization within pore spaces, elongate pseudomorphs of melt films along grain boundaries, minerals with low dihedral angles as small as <10° and up to <60°, and interconnected 3D melt pseudomorph networks. Reaction microstructures with highly irregular contact boundaries are observed at the field and thin‐section scale in remnant islands of original rock and replaced grains, respectively. We infer that the hornblende‐rich body was formed by modification of the host GG in situ due to reaction between an externally derived, reactive, hydrous gabbroic to intermediate melt percolating via porous melt flow through an actively deforming zone. Extensive melt–rock interaction and metasomatism occurred via coupled dissolution–precipitation, triggered by chemical disequilibrium between the host rock and the fluxing melt. As a result, the host plagioclase and pyroxene became unstable and were reacted and dissolved into the melt, while hornblende and to a lesser extent clinozoisite and garnet grew replacing the unstable phases. Our study shows that hornblendite rocks commonly observed within deep crustal sections, and attributed to cumulate fractionation processes, may instead delineate areas of deformation‐assisted, channelized reactive porous melt flow formed by melt‐mediated coupled dissolution–precipitation replacement reactions

Parton distribution functions and quark orbital motion

Covariant version of the quark-parton model is studied. Dependence of the structure functions and parton distributions on the 3D quark intrinsic motion is discussed. The important role of the quark orbital momentum, which is a particular case of intrinsic motion, appears as a direct consequence of the covariant description. Effect of orbital motion is substantial especially for polarized structure functions. At the same time, the procedure for obtaining the quark momentum distributions of polarized quarks from the combination of polarized and unpolarized structure functions is suggested.Comment: 17 pages, 2 figures, 1 table. Paper is accepted for publication in Eur.Phys.J.

Women with anorexia nervosa and bulimia nervosa : Individual and family characteristics, with particular emphasis on perfectionism

This study investigated socio-cultural, family and individual factors associated with anorexia and bulimia nervosa, with particular emphasis on dysfunctional perfectionism, and adopting a general social learning perspective. Theories of the development of eating disorders were interwoven with theories of the development of perfectionism. A model was proposed for the development of anorexia and bulimia nervosa via a dysfunctional perfectionism pathway. The 135 participants, aged 18 to 40 years, were women with anorexia nervosa (N=25), bulimia nervosa (N=32), Type 1 diabetes (N= 53, a North Canterbury population-based sample), and healthy women students (N=25). The women with eating disorders were recruited from various treatment centres throughout New Zealand. Participants completed a battery of seven self-report psychometric tests, namely, the Eating Disorder Inventory-2 (EDI-2), Beck Depression Inventory (BDI), Multidimensional Perfectionism Scale (MPS), Setting Conditions for Anorexia Nervosa Scale (SCANS), Tridimensional Personality Questionnaire (TPQ), Parental Bonding Instrument (PBI), and Family Environment Scale (FES). Analysis of Covariance, using the BDI as a covariate, revealed that, in addition to measures concerned with weight, shape and dieting, both anorexia and bulimia nervosa group means were significantly higher than both healthy and diabetes group means for EDI-2 Interpersonal Distrust and Social Insecurity; MPS Concern over Mistakes, Personal Standards, and Parental Criticism; and TPQ Harm A voidance, and significantly different from the healthy group mean for MPS Parental Expectations; SCANS Perfectionism; and PBI Maternal Protection, Maternal Care, and Paternal Care. Correlational analyses confirmed hypothesized moderate or strong associations between some perfectionism measures and other characteristics of women with eating disorders, such as a harm-avoidant temperament, and perceptions of maternal overprotection. Discriminant function analysis revealed seven variables, in combination, that maximally discriminated between eating disordered and non-eating disordered groups: three EDI-2 variables of Drive for Thinness, Ineffectiveness, and Social Insecurity, three MPS subscales of Concern over Mistakes, Personal Standards, and Doubts about Actions, and the BDI. Of the three instruments measuring perfectionism, in this study, only the MPS effectively discriminated between eating disordered and non-eating disordered groups. Findings indicated the importance of controlling for depression when comparing eating disordered groups with other groups, and that dysfunctional perfectionism is largely independent of the mood of the respondent. Findings suggest that the PBI may be limited by cultural sensitivity. Findings led to questioning of the applicability of the EDI-SC to diabetes groups and of the validity of the Novelty Seeking and Reward Dependence Dimensions of the TPQ. In concluding that dysfunctional perfectionism is a key personality characteristic of women with anorexia and bulimia nervosa, it is argued that multidimensional measures of perfectionism provide more insight than unidimensional measures into the dysfunctional facets of perfectionism, and that perfectionism per se is not necessarily problematic. Dysfunctional perfectionism may distinguish psychopathology associated with anorexia and bulimia nervosa from numerous other forms of psychopathology, including depression. Although aetiological factors were not assessed in this study, the MPS and PBI, considered in conjunction with the theoretical literature, may provide insight into the development of dysfunctional perfectionism. This has implications for the treatment and prevention of eating disorders

Finite Temperature Casimir Effect for a Massless Fractional Klein-Gordon field with Fractional Neumann Conditions

This paper studies the Casimir effect due to fractional massless Klein-Gordon field confined to parallel plates. A new kind of boundary condition called fractional Neumann condition which involves vanishing fractional derivatives of the field is introduced. The fractional Neumann condition allows the interpolation of Dirichlet and Neumann conditions imposed on the two plates. There exists a transition value in the difference between the orders of the fractional Neumann conditions for which the Casimir force changes from attractive to repulsive. Low and high temperature limits of Casimir energy and pressure are obtained. For sufficiently high temperature, these quantities are dominated by terms independent of the boundary conditions. Finally, validity of the temperature inversion symmetry for various boundary conditions is discussed.Comment: 31 page

Expansion dynamics of Pb-Pb collisions at 40 A GeV/c viewed by negatively charged hadrons

In this paper we present results on transverse mass spectra and Hanbury-Brown and Twiss correlation functions of negatively charged hadrons, which are expected to be mostly negative pions, measured in Pb-Pb collisions at 40 A GeV/c beam momentum. Based on these data, the collision dynamics and the space-time extent of the system at the thermal freeze-out are studied over a centrality range corresponding to the most central 53% of the Pb--Pb inelastic cross section. Comparisons with freeze-out conditions of strange particles and HBT results from other experiments are discussed.Comment: 29 pages, 18 figure

Understanding the proton's spin structure

We discuss the tremendous progress that has been towards an understanding of how the spin of the proton is distributed on its quark and gluon constituents. This is a problem that began in earnest twenty years ago with the discovery of the proton ``spin crisis'' by the European Muon Collaboration. The discoveries prompted by that original work have given us unprecedented insight into the amount of spin carried by polarized gluons and the orbital angular momentum of the quarks.Comment: Review article for J. Phys. G, 1 figure, 22 page

Strangeness enhancements at central rapidity in 40 A GeV/c Pb-Pb collisions

Results are presented on neutral kaon, hyperon and antihyperon production in Pb-Pb and p-Be interactions at 40 GeV/c per nucleon. The enhancement pattern follows the same hierarchy as seen in the higher energy data - the enhancement increases with the strangeness content of the hyperons and with the centrality of collision. The centrality dependence of the Pb-Pb yields and enhancements is steeper at 40 than at 158 A GeV/c. The energy dependence of strangeness enhancements at mid-rapidity is discussed.Comment: 15 pages, 10 figures and 3 tables. Presented at International Conference on Strangeness in Quark Matter (SQM2009), Buzios, Rio de Janeiro, Brazil, 27 Sept - 2 Oct 2009. Submitted to J.Phys.G: Nucl.Part.Phys, one reference adde

Rapidity distributions around mid-rapidity of strange particles in Pb-Pb collisions at 158 AA GeV/c

The production at central rapidity of K0s, Lambda, Xi and Omega particles in Pb-Pb collisions at 158 A GeV/c has been measured by the NA57 experiment over a centrality range corresponding to the most central 53% of the inelastic Pb-Pb cross section. In this paper we present the rapidity distribution of each particle in the central rapidity unit as a function of the event centrality. The distributions are analyzed based on hydrodynamical models of the collisions.Comment: 15 pages, 10 figure