Viscoelasticity of radiation-formed PVA/PVP hydrogel

The dynamic theological behaviour of gamma-irradiated 12.8 wt% poly(vinyl alcohol) (PVA), 12.8 wt% poly(vinyl pyrrolidone) (PVP), and a blend of 8 wt% PVA and 4.8 wt% PVP aqueous solutions have been studied pre- and post-gelation. The non-irradiated solutions displayed theological behaviour typical of dilute to semi-dilute polymer solutions, with the complex viscosity being independent of the frequency and shear rate (i.e. Newtonian behaviour) over the range of frequencies tested and the loss modulus G(omega) and storage modulus G(omega) being nearly proportional to omega and omega(2) respectively. After a set of doses of gamma-radiation, the magnitudes of the dynamic moduli G'(omega) and G(omega) increased as the absorbed dose increased, with notable differences between the two homopolymers and the blend. The stages of gelation were effectively monitored by means of dynamic theological measurements, allowing the possible mechanisms of network formation to be elucidated. The doses required for gelation of the PVA, PVP, and blend samples, determined on the basis of the Winter and Chambon criteria for gelation, were found to be 12 kGy for the 12.8 wt% PVA, 4 kGy for the 12.8 wt% PVP, and 5 kGy for the 8 wt% PVA/4.8 wt% PVP solutions. The unexpected lower gelation dose demonstrated by the blend sample, compared with predictions based on the blend composition, and the associated gelation mechanism are also discussed.

From radical to banal evil: Hannah Arendt against the justification of the unjustifiable

Two central strands in Arendt's thought are the reflection on the evil of Auschwitz and the rethinking in terms of politics of Heidegger's critique of metaphysics. Given Heidegger's taciturnity regarding Auschwitz and Arendt's own taciturnity regarding the philosophical implications of Heidegget's political engagement in 1933, to set out how these strands interrelate is to examine the coherence of Arendt's thought and its potential for a critique of Heidegger. By refusing to countenance a theological conception of the evil of Auschwitz, Arendt consolidates the break with theology that Heidegger attempts through his analysis of the essential finitude of Dasein. In the light of Arendt's account of evil, it is possible to see the theological vestiges in Heidegger's ontology. Heidegger's resumption of the question concerning the categorical interconnections of the ways of Being entails an abandonment of finitude: he accommodates and tacitly justifies that which can have no human justification.

Segregation band formation in Al-Si die castings

Banded defects are often found in high-pressure die castings. These bands can contain segregation, porosity, and/or tears, and changing casting conditions and alloy are known to change the position and make-up of the bands. Due to the complex, dynamic nature of the high-pressure die-casting (HPDC) process, it is very difficult to study the effect of individual parameters on band formation. In the work presented here, bands of segregation similar to those found in cold-chamber HPDC aluminum alloys were found in laboratory gravity die castings. Samples were cast with a range of fraction solids from 0 to 0.3 and the effect of die temperature and external solid fraction on segregation bands was investigated. The results are considered with reference to the theological properties of the filling semisolid metal and a formation mechanism for bands is proposed by considering flow past a solidifying immobile wall layer.

Numerical simulation of abrupt contraction flows using the Double Convected Pom-Pom model

The Double Convected Pom-Pom model was recently introduced to circumvent some numerical and theological defects found in other formulations of the Pom-Pom concept. It is used here for the simulation of a benchmark problem: the flow in an abrupt planar contraction. The predictions are compared with birefringence measurements and show reasonable quantitative agreement with experimental data. A parametric study is also carried out with the aim of analysing the effect of the branching parameter on vortex dynamics and extrudate swell. The results show that the Double Convected Pom-Pom model (DCPP) model is able to discriminate between branched and linear macromolecular structures in accordance with experimental observations. In that respect, the role of the extensional properties in determining complex flow behaviour is stressed. Also, the ratio of the first normal stress difference to the shear stress appears to play a major role in die swell observation. For the time being, the role of the second normal stress difference appears to be less obvious to evaluate in this complex flow. (C) 2004 Elsevier B.V. All rights reserved.

Judicial (in)activism in Australia's secular commonwealth

his article addresses two aspects of Australia's soft secular government. The first aspect explains how, and asks why, judges have been inactive in helping to draw the contours of secular government in Australia. The principal reason is that much of the social regulation that provokes the interest of faith-based groups is the constitutional concern of the States, and no State Constitution claims to coordinate relations between church and state. Moreover, the electorate has twice refused to pass referenda, in 1944 and 1988, for extending a constitutional demand of secular governance to the States. However, this is not so for the Commonwealth. It falls under the restrictions of section 116 of the federal Constitution, which states: The Commonwealth shall not make any law for establishing any religion ('the establishment clause') or for imposing any religious observance, or for prohibiting the free exercise of any religion ('the free exercise clause'), and no religious test shall be required as a qualification for any office or public trust under the Commonwealth. As will be explained, while methods of legal interpretation suggest that section 116's establishment clause could place mild demands of non-discrimination on the federal Parliament, judicial inactivity in policing such demands on the Commonwealth, paradoxically, has arguably been secured by judicial activism in the High Court. A second aspect of secular government addressed is the High Court's disposal of 'the separation of church and state' as a constitutional principle in Australia. The contrast, of course, is to the United States, where for sixty years 'separation' has been given uneven recognition as a rule of constitutional law, and has undoubtedly driven the development of hard forms of secular governance in that country. The centrepiece of American secular government is the 1971 decision in Lemon v Kurtzman, where the US Supreme Court held that valid legislation had to pass three tests, ie: First, the statute must have a secular legislative purpose; second, its principal or primary effect must be one that neither advances nor inhibits religion .. . finally, the statute must not foster 'an excessive government entanglement with religion. The third 'entanglement' prong of Lemon is the modern, less ambitious, form of the 'wall of separation', prohibiting too close an engagement between church and state. As this paper will demonstrate, 'entanglement's' destiny shows how unlikely it is that 'separation' can survive as a meaningful constitutional principle in the USA. And, it will also be argued that 'separation' has even poorer prospects for import to Australia.

Kierkegaard as a paradoxical therapist

The essential problem that Soren Kierkegaard is concerned with in his authorship is that of becoming a Christian. It is argued that Kierkegaard's authorial strategy reflects the principles of paradoxical psychotherapy. These principles indicate that both the psychological problem and its solution involve an ironic process. In the Kierkegaardian frame of reference, the situation of the immature self is paradoxical, and so is the pathway to full selfhood. The philistine and the aesthete attempt to secure autonomy and personal freedom through an external orientation. But the way to the self is inwards. Consequently, these personalities get caught in an ironic process. The further they push outwards, the further they move away from the locus of genuine selfhood and freedom. This immature form of life can only lead to a loss of self and the associated experience of despair. Paradoxically, Kierkegaard advocates the choice of despair as the way to find oneself in God.

Dam break wave of thixotropic fluid

Thixotropy is the characteristic of a fluid to form a gelled structure over time when it is not subjected to shearing, and to liquefy when agitated. Thixotropic fluids are commonly used in the construction industry (e.g., liquid concrete and drilling fluids), and related applications include some forms of mud flows and debris flows. This paper describes a basic study of dam break wave with thixotropic fluid. Theoretical considerations were developed based upon a kinematic wave approximation of the Saint-Venant equations down a prismatic sloping channel. A very simple thixotropic model, which predicts the basic theological trends of such fluids, was used. It describes the instantaneous state of fluid structure by a single parameter. The analytical solution of the basic flow motion and theology equations predicts three basic flow regimes depending upon the fluid properties and flow conditions, including the initial degree of jamming of the fluid (related to its time of restructuration at rest). These findings were successfully compared with systematic bentonite suspension experiments. The present work is the first theoretical analysis combining the basic principles of unsteady flow motion with a thixotropic fluid model and systematic laboratory experiments.