Continuous Elastic Phase Transitions in Pure and Disordered Crystals

We review the theory of second--order (ferro--)elastic phase transitions, where the order parameter consists of a certain linear combination of strain tensor components, and the accompanying soft mode is an acoustic phonon. In three--dimensional crystals, the softening can occur in one-- or two--dimensional soft sectors. The ensuing anisotropy reduces the effect of fluctuations, rendering the critical behaviour of these systems classical for a one--dimensional soft sector, and classical with logarithmic corrections in case of a two--dimensional soft sector. The dynamical critical exponent is $z = 2$, and as a consequence the sound velocity vanishes as $c_s \propto | T - T_c |^{1/2}$, while the phonon damping coefficient is essentially temperature--independent. Disorder may lead to a variety of precursor effects and modified critical behaviour. Defects that locally soften the crystal may induce the phenomenon of local order parameter condensation. When the correlation length of the pure system exceeds the average defect separation $n_{\rm D}^{-1/3}$, a disorder--induced phase transition to a state with non--zero average order parameter can occur at a temperature $T_c(n_{\rm D})$ well above the transition temperature $T_c^0$ of the pure crystal. Near $T_c^0$, the order--parameter curve, susceptibility, and specific heat appear rounded. For $T < T_c(n_{\rm D})$ the spatial inhomogeneity induces a static central peak with finite $q$ width in the scattering cross section, accompanied by a dynamical component that is confined to the very vicinity of the disorder--induced phase transition.Comment: 26 pages, Latex (rs.sty now IS included), 11 figures can be obtained from U.C. T\"auber ([email protected]); will appear in Phil. Trans. Roy. Soc. Lond. A (October 1996

Geriatric Psychiatry and Elder Law: Speaking a Common Language

In his introductory column, Dr. Finlayson discusses issues of competency and informed consent involving the elderly. Dr. Finlayson discusses these issues from a medical perspective demonstrating how the legal and medical issues relating to the elderly and mental health often intersect

The Assessment of Mental Competence: Factors Affecting the Process

In this column, the author examines factors that can complicate the assessment of determining a patient\u27s mental competence

Geriatric Psychiatry and Elder Law: Speaking a Common Language

In his introductory column, Dr. Finlayson discusses issues of competency and informed consent involving the elderly. Dr. Finlayson discusses these issues from a medical perspective demonstrating how the legal and medical issues relating to the elderly and mental health often intersect

The Development and implementation of industry informed inquiry-based units for chemistry teachers (ESTABLISH project)

El projecte ESTABLISH (7PM) té com a objectiu incrementar l'ús de metodologies d'ensenyament de les ciències basades en la indagació (ECBI) a les aules d'Europa. Mitjançant el subministrament de material didàctic (unitats ESTABLISH), reforçat per experiències reals proporcionades per la indústria, i el corresponent suport de formació educativa, tant per a professorat actiu com per a professorat en formació (Programes de Formació del Professorat ESTABLISH), els professors tenen a l'abast una àmplia gamma de recursos adequats per desenvolupar un ensenyament propi. En aquest treball s'analitza una de les unitats ESTABLISH i s'emfatitza el desenvolupament de vincles industrials. Es discuteix una sèrie d'enfocaments diferents dels vincles industrials per proporcionar un context als reptes actuals del disseny de materials didàctics.ESTABLISH (FP7 project) aims to increase the use of inquiry-based science education (IBSE) methodologies in classrooms across Europe. Through the provision of teaching and learning materials (ESTABLISH units), enhanced by authentic experiences provided by industry, and educational supports for both in-service and preservice teachers (ESTABLISH Teacher Education Programmes), teachers have a range of suitable material to develop their own teaching. This paper discusses one of the ESTABLISH units and emphasises the development of the industri· al links. A number of different approaches to industrial links are discussed, from providing context to actual design challenges

Parasites of the larch casebearer, Coleophora laricella (Lepidoptera: Coleophoridae), in the West Kootenay area, British Columbia

The parasite complex of the larch casebearer, &lt;i&gt;Coleophora laricella&lt;/i&gt; (Hbn.), was investigated in the Kootenay area of British Columbia in 1973 and 1974. Forty-one species of hymenopterous parasites were obtained from rearings of almost 153,000 final-instar host larvae and pupae. In 1973 and 1974, 31 and 24 species, respectively, were reared, with 14 common to both years. Twenty-nine of these, in 24 genera, were confirmed as larch casebearer parasites by individual rearings and by reports in the literature. No parasites were obtained from eggs, needle-mining larvae, or third-instar case-bearing larvae. The highest total percentage parasitism was 17.7% in 1973 and 24.5% in 1974, both at Rossland. In Collection II the &lt;i&gt;Dicladocerus&lt;/i&gt; spp. complex comprised 46.0% of the total parasitism in 1973. and 63.8% of the total in 1974: it was the most abundant at four of the eight collecting sites in 1973 and 13 of the 14 sites in 1974. &lt;i&gt;Spilochalcis albifroms&lt;/i&gt; (Walsh) comprised 32.8% and 23.5% of the total parasitism in the years 1973 and 1974 respectively; it was most abundant at three collection sites in 1973 and at two in 1974. &lt;i&gt;Mesopolobus&lt;/i&gt; sp. constituted 4.9% of the total in 1973 and 9.9% in 1974. Larch case bearer densities in the first collection in 1973 were highest at Fruitvale and Shoreacres with 150 and 130 cases per 100 fascicles respectively; in 1974, the highest host densities in the first collection were at Kootenay Bay and Fruitvale with 48 and 41 cases per 100 fascicles respectively

Easing the transition from secondary school to higher education through recognition of the skills of our students

This short communication discusses research, which has investigated students‟ self-perception of their skills. This was to identify which skills they felt most and least confident in upon starting university. General and scientific and practical skills as well as skills related to improving learning were explored. The results suggested that students felt most confident in working in groups, interacting with people to obtain the necessary information and assistance, and observing chemical events and changes among others. In contrast students felt least confident in planning and presenting an oral presentation, analysing and evaluating experimental data, and using the internet and other resources to gain information. Details of how the findings were used to make effective changes to an existing module will be discussed. Furthermore, the relevance of this in terms of supporting our first year students in their transition to university-level work and subsequently planning appropriate modules will be discussed in relation to the recently published results from the UK Physical Sciences Centre Review of the Student Learning Experience in Chemistry and in light of the Department for Business Innovation and Skills Higher Ambitions and Skills for Growth papers

An experimental and theoretical determination of oscillatory shear-induced crystallization processes in viscoelastic photonic crystal media

A study is presented of the oscillatory shear-ordering dynamics of viscoelastic photonic crystal media, using an optical shear cell. The hard-sphere/“sticky”-shell design of these polymeric composite particles produces athermal, quasi-solid rubbery media, with a characteristic viscoelastic ensemble response to applied shear. Monotonic crystallization processes, as directly measured by the photonic stopband transmission, are tracked as a function of strain amplitude, oscillation frequency, and temperature. A complementary generic spatio-temporal model is developed of crystallization due to shear-dependent interlayer viscosity, giving propagating crystalline fronts with increasing applied strain, and a gradual transition from interparticle disorder to order. The introduction of a competing shear-induced flow degradation process, dependent on the global shear rate, gives solutions with both amplitude and frequency dependence. The extracted crystallization timescales show parametric trends which are in good qualitative agreement with experimental observations