2,390 research outputs found
Teaching Narrative Interviewing: Reflecting, Narrating, and Becoming-In-Action
Qualitative inquiry teachers often seek powerful pedagogies to improve their studentsâ understandings. Using our experience leading a doctoral workshop, we share our method for teaching narrative interviewing using Schönâs (1983) âreflection-in-action,â meaning teachers and students reflect in the moment. We also root our pedagogy in Jerome Brunerâs (1986, 1990) narrative as a mode of thinking and a mode of being, a philosophy exploring the ways learners story their own and othersâ lives. Describing our doctoral workshop, we highlight Laura, a recent graduate, narrating and becoming a qualitative inquirer. We conclude with a sample teaching lesson, designed to enhance studentsâ reflective research practices
Elasticity of smectic liquid crystals with focal conic domains
We study the elastic properties of thermotropic smectic liquid crystals with
focal conic domains (FCDs). After the application of the controlled preshear at
different temperatures, we independently measured the shear modulus G' and the
FCD size L. We find out that these quantities are related by the scaling
relation G' ~ \gamma_{eff}/L where \gamma_{eff} is the effective surface
tension of the FCDs. The experimentally obtained value of \gamma_{\rm eff}
shows the same scaling as the effective surface tension of the layered systems
\sqrt{KB} where K and B are the bending modulus and the layer compression
modulus, respectively. The similarity of this scaling relation to that of the
surfactant onion phase suggests an universal rheological behavior of the
layered systems with defects.Comment: 14 pages, 7 figures, accepted for publication in JPC
Force-Extension Relation and Plateau Modulus for Wormlike Chains
We derive the linear force-extension relation for a wormlike chain of
arbitrary stiffness including entropy elasticity, bending and thermodynamic
buckling. From this we infer the plateau modulus of an isotropic
entangled solution of wormlike chains. The entanglement length is
expressed in terms of the characteristic network parameters for three different
scaling regimes in the entangled phase. The entanglement transition and the
concentration dependence of are analyzed. Finally we compare our findings
with experimental data.Comment: 5 pages, 1 eps-figure, to appear in PR
Multivisceral intestinal transplantation: Surgical pathology
We report the diagnostic surgical pathology of two children who underwent multivisceral abdominal transplantation and survived for 1 month and 6 months. There is little relevant literature, and diagnostic criteria for the various clinical possibilities are not established; this is made more complicated by the simultaneous occurrence of more than one process. We based our interpretations on conventional histology, augmented with immunohistology, including HLA staining that distinguished graft from host cells in situ. In some instances functional analysis of T cells propagated from the same biopsies was available and was used to corroborate morphological interpretations. A wide spectrum of changes was encountered. Graft-versus-host disease, a prime concern before surgery, was not seen. Rejection was severe in 1 patient, not present in the other, and both had evidence of lymphoproliferative disease, which was related to Epstein-Barr virus. Bacterial translocation through the gut wall was also a feature in both children. This paper documents and illustrates the various diagnostic possibilities.. © 1989 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted
Elasticity of Gaussian and nearly-Gaussian phantom networks
We study the elastic properties of phantom networks of Gaussian and
nearly-Gaussian springs. We show that the stress tensor of a Gaussian network
coincides with the conductivity tensor of an equivalent resistor network, while
its elastic constants vanish. We use a perturbation theory to analyze the
elastic behavior of networks of slightly non-Gaussian springs. We show that the
elastic constants of phantom percolation networks of nearly-Gaussian springs
have a power low dependence on the distance of the system from the percolation
threshold, and derive bounds on the exponents.Comment: submitted to Phys. Rev. E, 10 pages, 1 figur
Scope and Mechanistic Study of the Coupling Reaction of α,ÎČ-Unsaturated Carbonyl Compounds with Alkenes: Uncovering Electronic Effects on Alkene Insertion vs Oxidative Coupling Pathways
The cationic ruthenium-hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4â (1) was found to be a highly effective catalyst for the intermolecular conjugate addition of simple alkenes to α,ÎČ-unsaturated carbonyl compounds to give (Z)-selective tetrasubstituted olefin products. The analogous coupling reaction of cinnamides with electron-deficient olefins led to the oxidative coupling of two olefinic CâH bonds in forming (E)-selective diene products. The intramolecular version of the coupling reaction efficiently produced indene and bicyclic fulvene derivatives. The empirical rate law for the coupling reaction of ethyl cinnamate with propene was determined as follows: rate = k[1]1[propene]0[cinnamate]â1. A negligible deuterium kinetic isotope effect (kH/kD = 1.1 ± 0.1) was measured from both (E)-C6H5CHâC(CH3)CONHCH3 and (E)-C6H5CDâC(CH3)CONHCH3 with styrene. In contrast, a significant normal isotope effect (kH/kD = 1.7 ± 0.1) was observed from the reaction of (E)-C6H5CHâC(CH3)CONHCH3 with styrene and styrene-d8. A pronounced carbon isotope effect was measured from the coupling reaction of (E)-C6H5CHâCHCO2Et with propene (13C(recovered)/13C(virgin) at CÎČ = 1.019(6)), while a negligible carbon isotope effect (13C(recovered)/13C(virgin) at CÎČ = 0.999(4)) was obtained from the reaction of (E)-C6H5CHâC(CH3)CONHCH3 with styrene. Hammett plots from the correlation of para-substituted p-X-C6H4CHâCHCO2Et (X = OCH3, CH3, H, F, Cl, CO2Me, CF3) with propene and from the treatment of (E)-C6H5CHâCHCO2Et with a series of para-substituted styrenes p-Y-C6H4CHâCH2 (Y = OCH3, CH3, H, F, Cl, CF3) gave the positive slopes for both cases (Ï = +1.1 ± 0.1 and +1.5 ± 0.1, respectively). Eyring analysis of the coupling reaction led to the thermodynamic parameters, ÎH⧧ = 20 ± 2 kcal molâ1 and ÎS⧧ = â42 ± 5 eu. Two separate mechanistic pathways for the coupling reaction have been proposed on the basis of these kinetic and spectroscopic studies
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