A comparison of the growth curves of the foliose lichen Parmelia conspersa determined by a cross-sectional study and by direct measurement

Changes in the radial growth rate (RGR mm/yr) through life were studied in thalli of the foliose lichen Parmelia conspersa by two methods: (1) a cross-sectional study (Study A) in which the RGR was measured in 60 thalli from 0.2 to 13 cm in diameter, and (2) by radial growth measurements over 4.5 years of fragments, consisting of a single major lobe, which were removed from large thalli and glued to pieces of slate (Study B). Both studies suggested there was a phase of increasing RGR in small thalli followed by a more constant phase, the latter beginning at approximately a thallus radius of 6-8 mm. However, in Study B significantly increased RGR was observed during the second 6-month growth period. This phase of growth was more likely to be due to an increase in lobe width than to an effect of climate. In addition, a lobe in a large thallus with both adjacent lobes removed significantly increased in width over 1 year compared with control lobes. These results suggest that (1) mean lobe width in a thallus may be determined by the intensity of marginal competition between adjacent lobes, and (2) changes in lobe width during the life of a lichen thallus may be a factor determining the establishment of the linear phase of growth in foliose lichens. © 1992.

Deformations of the pneumatic tyre

A mathematical model is developed for the general pneumatic tyre. The model will permit the investigations of tyre deformations produced by arbitrary external loading, and will enable estimates to be made of the distributions of applied and reactive forces. The principle of Finite Elements is used to idealise the composite tyre structure, each element consisting of a triangle of double curvature with varying thickness. Large deflections of' the structure are accomodated by the use of an iterative sequence of small incremental steps, each of' which obeys the laws of linear mechanics. The theoretical results are found to compare favourably with the experimental test data obtained from two different types of ttye construction. However, limitations in the discretisation process has prohibited accurate assessments to be made of stress distributions in the regions of high stress gradients ..

Developments and extensions of Roth's method of double Fourier series with applications to the solution of electromagnetic field problems

The first part of the thesis compares Roth's method with other methods, in particular the method of separation of variables and the finite cosine transform method, for solving certain elliptic partial differential equations arising in practice. In particular we consider the solution of steady state problems associated with insulated conductors in rectangular slots. Roth's method has two main disadvantages namely the slow rate of con­vergence of the double Fourier series and the restrictive form of the allowable boundary conditions. A combined Roth-separation of variables method is derived to remove the restrictions on the form of the boundary conditions and various Chebyshev approximations are used to try to improve the rate of convergence of the series. All the techniques are then applied to the Neumann problem arising from balanced rectangular windings in a transformer window. Roth's method is then extended to deal with problems other than those resulting from static fields. First we consider a rectangular insulated conductor in a rectangular slot when the current is varying sinusoidally with time. An approximate method is also developed and compared with the exact method.The approximation is then used to consider the problem of an insulated conductor in a slot facing an air gap. We also consider the exact method applied to the determination of the eddy-current loss produced in an isolated rectangular conductor by a transverse magnetic field varying sinusoidally with time. The results obtained using Roth's method are critically compared with those obtained by other authors using different methods. The final part of the thesis investigates further the application of Chebyshdev methods to the solution of elliptic partial differential equations; an area where Chebyshev approximations have rarely been used. A poisson equation with a polynomial term is treated first followed by a slot problem in cylindrical geometry.

Survival or success? A critical exploration of the use of 'double-voiced discourse' by women business leaders in the UK

This article considers whether using leadership language may be one under-explored reason why there continues to be a significant lack of women at executive level. Do women make less of a linguistic impact in the boardroom than men? By analysing linguistic data from senior management meetings and follow-up interviews in seven multinational UK companies, we suggest that senior women and men use a very similar range of linguistic strategies to lead their teams except in one key respect. Women appear to monitor and regulate their use of language more than men, adjusting what they say in the light of their colleagues’ concerns and agendas. This use of ‘double-voiced discourse’ (Bakhtin, 1994/1963) enables women to survive in a male-dominated business world, but this can sometimes make their voice ‘harder to hear’. However, double-voiced discourse is also a form of linguistic expertise and potentially might offer women leaders a strategy for success.

Chemical reactions of double bonds in activated carbon:microwave and bromination methods

The reaction of localised C=C bonds on the surface of activated carbons has been shown to be an effective method of chemical modification especially using microwave-assisted reactions.

On the Mixed Modulus of Smoothness and a Class of Double Fourier Series

MSC 2010: 42A32; 42A20

Two Educators’ Experiences of Double Dose Reading Classes

The purpose of this qualitative study was to gain knowledge of the phenomenon of double dose reading classes. A reading coach and a reading teacher were interviewed. Data revealed teachers navigate a complicated set of negotiations in order to deliver quality instruction while simultaneously satisfying mandated requirements from supervisors.

An experimental study of the effects of double-diffusive convention processes during the solification of binary alloys

Experiments were conducted to show the effects of thermal and geometric boundary conditions on the liquid pool of a binary alloy system which is undergoing phase change, solidification. Transparent analogue solutions were selected for study and experimental apparatus were designed and built. Thermal distribution and concentration data were collected and analysed for the melt pool of various selected geometries and boundary conditions of the systems under study. The data indicate-that characteristic flows develop for both Hypereutectic and Hypoeutectic concentration levels and that the development of macrosegregation and microsegregation defects in continuous casting materials can be minimised by the adjustment of the process variables.

Impact of scatterer density on the performances of double-scattering MIMO channels

We investigate a MIMO double-scattering model with both local and remote scatterers, aiming to investigate the effect of scatterer density on channel performances, such as capacity, correlation, and the condition number of the channel matrix in flat and frequency-selective fading channels. The investigations are carried out in terms of scatterer density. It is shown that in flat fading channels the scatterer density has a marginal effect on channel performances when the area of the two scatterer zones is fixed, while a significant impact is observed when the area of the scatterer zones is allowed to change. In frequency-selective fading channels, no matter the area of the scatterer zones is fixed or not, scatterer density can affect the channel capacity to a certain degree that depends on the length of the coding block of the transmitted signals. © 2010 IEEE.

Geodesically reversible Finsler 2-spheres of constant curvature

A Finsler space is said to be geodesically reversible if each oriented geodesic can be reparametrized as a geodesic with the reverse orientation. A reversible Finsler space is geodesically reversible, but the converse need not be true. In this note, building on recent work of LeBrun and Mason, it is shown that a geodesically reversible Finsler metric of constant flag curvature on the 2-sphere is necessarily projectively flat. As a corollary, using a previous result of the author, it is shown that a reversible Finsler metric of constant flag curvature on the 2-sphere is necessarily a Riemannian metric of constant Gauss curvature, thus settling a long- standing problem in Finsler geometry.

The effect of poly(lactide)-poly(carbonate) based block copolymers on the morphology and crystallization of double crystalline poly(lactide)/poly(ε-caprolactone) blends

Block copolymers of poly(lactide) and poly(carbonate) were synthetized in three different compositions and characterized by 1H-NMR and ATR analyses. The compatibilization effect of this copolymers on 80/20 (w/w%) PLA/PCL blend was evaluated. SEM micrographs show that all the blends exhibit the typical sea-island morphology characteristic of immiscible blends with PCL finely dispersed in droplets on a PLA matrix. Upon the addiction of the copolymers a reduction on PCL droplets size is observable. At the same time, a Tg depression of the PLA phase is detected when the copolymers are added in the blend. These results indicate that these copolymers are effective as compatibilizers. The copolymer that acts as the best compatibilizer is the one characterized by the same amount of PLA and PC as repeating units. As result, in the blend containing this copolymer PLA phase exhibits the highest spherulitic growth rate. An analyses on PLA phase crystallization behaviour from the glassy state within the blends was evaluated by DSC experiments. Isothermal cold crystallization of the PLA phase is enhanced up an order of magnitude upon the blending with PCL. Annealing experiments demonstrated that the crystallization of the PCL phase induces the formation of active nuclei in PLA when cooled above cooled below Tg. When the crystallization rate of PCL is retarded, a reduction on PLA nucleation is observed.

ROC curves of obesity indicators have a predictive value for children hypertension aged 7-17 years

Objective: The aim of the study is to examine the distribution of integrated covariate and its association with blood pressure (BP) among children in Anhui province, China, and assess the predictive value of integrated covariate to children hypertension. Methods: A total of 2,828 subjects (1,588 male and 1,240 female) aged 7-17 years participated in this study. Height, weight, waistline, hipline and BP of all subjects were measured, obesity and overweight were defined by an international standard, specifying the measurement, the reference population, and the age and sex specific cut off points. High BP status was defined as systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) > 95th percentile for age and gender. Results: Our results revealed that the prevalence of children hypertension was 11.03%, the SBP and DBP of obesity group were significantly higher than that of normal group. Anthropometric obesity indices such as body mass index (BMI) were positively correlated with SBP and DBP. Integrated covariate had a better performance than the single covariate in the receiver-operating characteristic (ROC) curve, the cut-off value; the sensitivity and the specificity of the integrated covariate were 0.112, 0.577, 0.683, respectively. Conclusion: Integrated covariate is a simple and effective anthropometric index to identify childhood hypertension.

E-polynomial of SL(2,C)-character varieties of complex curves of genus 3.

We compute the E-polynomials of the moduli spaces of representations of the fundamental group of a complex curve of genus g = 3 into SL(2, C), and also of the moduli space of twisted representations. The case of genus g = 1, 2 has already been done in [12]. We follow the geometric technique introduced in [12], based on stratifying the space of representations, and on the analysis of the behaviour of the E-polynomial under fibrations.