Characterisation of the three-dimensional structure of earthworm burrow systems using image analysis and mathematical morphology

The aim of this work was to exemplify the specific contribution of both two- and three-dimensional (31)) X-ray computed tomography to characterise earthworm burrow systems. To achieve this purpose we used 3D mathematical morphology operators to characterise burrow systems resulting from the activity of an anecic (Aporrectodea noctunia), and an endogeic species (Allolobophora chlorotica), when both species were introduced either separately or together into artificial soil cores. Images of these soil cores were obtained using a medical X-ray tomography scanner. Three-dimensional reconstructions of burrow systems were obtained using a specifically developed segmentation algorithm. To study the differences between burrow systems, a set of classical tools of mathematical morphology (granulometries) were used. So-called granulometries based on different structuring elements clearly separated the different burrow systems. They enabled us to show that burrows made by the anecic species were fatter, longer, more vertical, more continuous but less sinuous than burrows of the endogeic species. The granulometry transform of the soil matrix showed that burrows made by A. nocturna were more evenly distributed than those of A. chlorotica. Although a good discrimination was possible when only one species was introduced into the soil cores, it was not possible to separate burrows of the two species from each other in cases where species were introduced into the same soil core. This limitation, partly due to the insufficient spatial resolution of the medical scanner, precluded the use of the morphological operators to study putative interactions between the two species.

Governing society today: Editors' introduction

The notion of governing society has for a long time seemed self-evident. Society was conceived as a totality coincident with a certain space, a territory, and occupied by a population. Governing was undertaken by a unified agency that acted upon the society of which it was also a specialized part--the government, or, more broadly, "the state." The notion of "governing society" thus referred unproblematically to the binary of state and society. The articles in this special issue of Alternatives, however, each in its own and different way, address the question of "governing society today."

Calculating current densities and fields produced by shielded magnetic resonance imaging probes

A method is presented for computing the fields produced by radio frequency probes of the type used in magnetic resonance imaging. The effects of surrounding the probe with a shielding coil, intended to eliminate stray fields produced outside the probe, are included. An essential feature of these devices is the fact that the conducting rungs of the probe are of finite width relative to the coil radius, and it is therefore necessary to find the distribution of current within the conductors as part of the solution process. This is done here using a numerical method based on the inverse finite Hilbert transform, applied iteratively to the entire structure including its shielding coils. It is observed that the fields are influenced substantially by the width of the conducting rungs of the probe, since induced eddy currents within the rungs become more pronounced as their width is increased. The shield is also shown to have a significant effect on both the primary current density and the resultant fields. Quality factors are computed for these probes and compared with values measured experimentally.

Cell-wall polysaccharides from Australian red algae of the family Solieriaceae (Gigartinales, Rhodophyta): Novel, highly pyruvated carrageenans from the genus Callophycus

Cell-wall polysaccharides from six species of red algae of the genus Callophycus were mainly galactans comprised predominantly of galactose (Gal) and 3,6-anhydrogalactose (AnGal), and were rich in pyruvate and sulfate. The Fourier Transform Infrared (FTIR) spectra of the polysaccharides superficially resembled that of alpha-carrageenan (composed of the repeating disaccharide carrabiose 2-sulfate), with major bands of absorption indicative of if-linked AnGal, axial 2-sulfate on 4-linked AnGal, and unsulfated, 3-linked Gal. The FTIR spectra of solutions of Callophycus polysaccharides in D2O-phosphate buffer displayed absorption, corresponding to the carboxylate anion of the pyruvate acetal substituent. Methylation analysis showed that 3,4,6-linked Galp (interpreted as 4,6-pyruvated, 3-linked Galp) and 2,4-linked AnGalp (interpreted as 4-linked AnGalp 2-sulfate) were the dominant links, together with significant quantities of 3-linked Galp. Proton-decoupled C-13 nuclear magnetic resonance (NMR) spectroscopy showed the polysaccharides to be composed predominantly of pyruvated carrageenans. The C-13 NMR spectra were completely assigned by a J-modulated spin-echo pulse sequence and 2D experiments employing gradient Heteronuclear Multiple Bond Correlation (HMBC), C-13/H-1 Heteronuclear Multiple Quantum Coherence (HMQC), and HMQC Total Correlation Spectroscopy (HMQC-TOCSY). The Callophycus galactans thus consist predominantly of the novel repeating disaccharide 4',6'-O-(1-carboxyethylidene)carrabiose 2-sulfate and minor amounts of the alpha-carrageenan repeating unit (carrabiose 2-sulfate), and other structural variations. (C) 1997 Elsevier Science Ltd.

Biochemical synthesis, purification and preliminary pharmacological evaluation of normorphine-3-glucuronide

Normorphine was synthesised from morphine by thermal decomposition of an N-alpha-chloroethylchloroformate adduct, and purified (> 98% purity) using semipreparative HPLC with ultraviolet detection. Normorphine-3-glucuronide (NM3G) was biochemically synthesised using the substrate normorphine, uridine diphosphoglucuronic acid and Sprague-Dawley rat liver microsomes in a 75% yield (relative to normorphine base). The synthesised NM3G was purified by precipitation and washing with acetonitrile. Determinations of purity using HPLC with electrochemical and ultraviolet detection confirmed that the NM3G produced was of high (> 99%) purity. Mass spectrometry, fourier transform infrared spectrophotometry and nuclear magnetic resonance spectrometry confirmed the structure, especially placement of the glucuronide moiety at the 3-phenolic position and not at the 17-nitrogen. Administration of NM3G by the intracerebroventricular (icy) route to rats in doses of 2.5 and 7.5 mu g resulted in the development of central nervous system (CNS) excitatory behavioural effects including myoclonus, chewing, wet-dog shakes, ataxia and explosive motor behaviour. At an icy dose of 7.5 mu g, NM3G also induced short periods of tonic-clonic convulsive activity. Thus, NM3G elicits CNS excitation following supraspinal administration in a manner analogous to morphine-3-glucuronide (M3G), the major metabolite of morphine (1). Further studies are required to determine whether NM3G attenuates morphine-induced antinociception in se similar manner to M3G.

MDA-based re-engineering with Object-Z

This paper describes a practical application of MDA and reverse engineering based on a domain-specific modelling language. A well defined metamodel of a domain-specific language is useful for verification and validation of associated tools. We apply this approach to SIFA, a security analysis tool. SIFA has evolved as requirements have changed, and it has no metamodel. Hence, testing SIFA’s correctness is difficult. We introduce a formal metamodelling approach to develop a well-defined metamodel of the domain. Initially, we develop a domain model in EMF by reverse engineering the SIFA implementation. Then we transform EMF to Object-Z using model transformation. Finally, we complete the Object-Z model by specifying system behavior. The outcome is a well-defined metamodel that precisely describes the domain and the security properties that it analyses. It also provides a reliable basis for testing the current SIFA implementation and forward engineering its successor.

Analytical solution and numerical model for the interface in a stratified long wave system

For a two layered long wave propagation, linearized governing equations, which were derived earlier from the Euler equations of mass and momentum assuming negligible friction and interfacial mixing are solved analytically using Fourier transform. For the solution, variations of upper layer water level is assumed to be sinosoidal having known amplitude and variations of interface level is solved. As the governing equations are too complex to solve it analytically, density of upper layer fluid is assumed as very close to the density of lower layer fluid to simplify the lower layer equation. A numerical model is developed using the staggered leap-forg scheme for computation of water level and discharge in one dimensional propagation having known amplitude for the variations of upper layer water level and interface level to be solved. For the numerical model, water levels (upper layer and interface) at both the boundaries are assumed to be known from analytical solution. Results of numerical model are verified by comparing with the analytical solutions for different time period. Good agreements between analytical solution and numerical model are found for the stated boundary condition. The reliability of the developed numerical model is discussed, using it for different a (ratio of density of fluid in the upper layer to that in the lower layer) and p (ratio of water depth in the lower layer to that in the upper layer) values. It is found that as ‘CX’ increases amplification of interface also increases for same upper layer amplitude. Again for a constant lower layer depth, as ‘p’ increases amplification of interface. also increases for same upper layer amplitude.

Matrix-product codes over Fq

Codes C-1,...,C-M of length it over F-q and an M x N matrix A over F-q define a matrix-product code C = [C-1 (...) C-M] (.) A consisting of all matrix products [c(1) (...) c(M)] (.) A. This generalizes the (u/u + v)-, (u + v + w/2u + v/u)-, (a + x/b + x/a + b + x)-, (u + v/u - v)- etc. constructions. We study matrix-product codes using Linear Algebra. This provides a basis for a unified analysis of /C/, d(C), the minimum Hamming distance of C, and C-perpendicular to. It also reveals an interesting connection with MDS codes. We determine /C/ when A is non-singular. To underbound d(C), we need A to be 'non-singular by columns (NSC)'. We investigate NSC matrices. We show that Generalized Reed-Muller codes are iterative NSC matrix-product codes, generalizing the construction of Reed-Muller codes, as are the ternary 'Main Sequence codes'. We obtain a simpler proof of the minimum Hamming distance of such families of codes. If A is square and NSC, C-perpendicular to can be described using C-1(perpendicular to),...,C-M(perpendicular to) and a transformation of A. This yields d(C-perpendicular to). Finally we show that an NSC matrix-product code is a generalized concatenated code.

A dynamic model with on-line identification for rotary sugar drying processes

A dynamic modelling methodology, which combines on-line variable estimation and parameter identification with physical laws to form an adaptive model for rotary sugar drying processes, is developed in this paper. In contrast to the conventional rate-based models using empirical transfer coefficients, the heat and mass transfer rates are estimated by using on-line measurements in the new model. Furthermore, a set of improved sectional solid transport equations with localized parameters is developed in this work to reidentified on-line using measurement data, the model is able to closely track the dynamic behaviour of rotary drying processes within a broad range of operational conditions. This adaptive model is validated against experimental data obtained from a pilot-scale rotary sugar dryer. The proposed modelling methodology can be easily incorporated into nonlinear model based control schemes to form a unified modelling and control framework.place the global correlation for the computation of solid retention time. Since a number of key model variables and parameters are identified on-line using measurement data, the model is able to closely track the dynamic behaviour of rotary drying processes within a broad range of operational conditions. This adaptive model is validated against experimental data obtained from a pilot-scale rotary sugar dryer. The proposed modelling methodology can be easily incorporated into nonlinear model based control schemes to form a unified modelling and control framework.

Analysis of Piezoelectric sensor to detect flexural waves

The electromechanical transfer characteristics of adhesively bonded piezoelectric sensors are investigated. By the use of dynamic piezoelectricity theory, Mindlin plate theory for flexural wave propagation, and a multiple integral transform method, the frequency-response functions of piezoelectric sensors with and without backing materials are developed and the pressure-voltage transduction functions of the sensors calculated. The corresponding simulation results show that the sensitivity of the sensors is not only dependent on the sensors' inherent features, such as piezoelectric properties and geometry, but also on local characteristics of the tested structures and the admittance and impedance of the attached electrical circuit. It is also demonstrated that the simplified rigid mass sensor model can be used to analyze successfully the sensitivity of the sensor at low frequencies, but that the dynamic piezoelectric continuum model has to be used for higher frequencies, especially around the resonance frequency of the coupled sensor-structure vibration system.

Flexural waves transmitted by rectangular piezoceramic transducers

Rectangular piezoceramic transducers are widely used in ultrasonic evaluation and health monitoring techniques and structural vibration control applications. In this paper the flexural waves excited by rectangular transducers adhesively attached to isotropic plates are investigated. In view of the difficulties in developing accurate analytical models describing the transfer characteristics of the transducer due to the complex electromechanical transduction processes and transducer-structure interactions involved, a combined theoretical-experimental approach is developed. A multiple integral transform method is used to describe the propagation behaviour of the waves in the plates, while a heterodyne Doppler laser vibrometer is employed as a non-contact receiver device. This combined theoretical-experimental approach enables the efficient characterization of the electromechanical transfer properties of the piezoelectric transducer which is essential for the development of optimized non-destructive evaluation systems. The results show that the assumption of a uniform contact pressure distribution between the transducer and the plate can accurately predict the frequency spectrum and time domain response signals of the propagating waves along the main axes of the rectangular transmitter element.

Analysis of flexural waves excited by rectangular contact type transducers

In this paper, an attempt was made to investigate a fundamental problem related to the flexural waves excited by rectangular transducers. Due to the disadvantages of the Green's function approach for solving this problem, a direct and effective method is proposed using a multiple integral transform method and contour integration technique. The explicit frequency domain solutions obtained from this newly developed method are convenient for understanding transducer behavior and theoretical optimization and experimental calibration of rectangular transducers. The time domain solutions can then be easily obtained by using the fast Fourier transform technique. (C) 2001 Elsevier Science B.V. All rights reserved.

Analysis of acousto-ultrasonic characteristics for contact-type transducers coupled to composite laminated plates

The acousto-ultrasonic (AU) input-output characteristics for contact-type transmitting and receiving transducers coupled to composite laminated plates are considered in this paper. Combining a multiple integral transform method, an ordinary discrete layer theory for the laminates and some simplifying assumptions for the electro-mechanical transduction behaviour of the transducers, an analytical solution is developed which can deal with all the wave processes involved in the AU measurement system, i.e, wave generation, wave propagation and wave reception. The spectral response of the normal contact pressure sensed by the receiving transducer due to an arbitrary input pulse excited by the transmitting transducer is obtained. To validate the new analytical-numerical spectral technique in the low-frequency regime, the results are compared with Mindlin plate theory solutions. Based on the analytical results, numerical calculations are carried out to investigate the influence of various external parameters such as frequency content of the input pulse, transmitter/receiver spacing and transducer aperture on the output of the measurement system. The results show that the presented analytical-numerical procedure is an effective tool for understanding the input-output characteristics of the AU technique for laminated plates. (C) 2001 Elsevier Science Ltd. All rights reserved.

Chemistry, properties, and phylogenetic implications of the methylated carrageenans from red algae of the genus Areschougia (Areschougiaceae, Gigartinales, Rhodophyta)

The three Australian-endemic species comprising the genus Aresehougia have been examined to determine the structure of their nonfibrillar wall components. The polysaccharide extracted from the most widely distributed species, A. congesta (Turner) J. Agardh, was shown by compositional analyses, Fourier transform infrared (FTIR) spectroscopy, linkage analysis, and C-13-NMR spectroscopy to be a carrageenan composed predominantly of the repeating disaccharides 6'-O-methylcarrabiose 2,4'-disulfate, carrabiose 2,4-disulfate (the repeating unit of L-carrageenan), 4',6'-O-(1-carboxyethylidene)carrabiose 2-sulfate, and 6'-O-methylcarrabiose 2-sulfate. The carrageenan also contained small amounts of 4-linked Galp residues, some bearing methyl ether substitution at O-3 and some possibly bearing sulfate ester and/or glycosyl substitutions at O-3. The A. congesta carrageenan had unique rheological properties, its gels having some similarities to those of commercial iota -carrageenan but with the viscosity of commercial lambda -carrageenan. Polysaccharides from A. ligulata Harvey ex J. Agardh and A. stuartii Harvey were shown by constituent sugar and FTIR analyses to be sulfated galactans rich in mono-O-methylgalactose. The carrageenan structures of Areschougia spp. were consistent with those of the genera Rhabdonia, Erythroclonium, and Austroclonium, the other genera constituting the family Areschougiaceae.

Specification, refinement and verification of concurrent systems - An integration of Object-Z and CSP

This paper presents a method of formally specifying, refining and verifying concurrent systems which uses the object-oriented state-based specification language Object-Z together with the process algebra CSP. Object-Z provides a convenient way of modelling complex data structures needed to define the component processes of such systems, and CSP enables the concise specification of process interactions. The basis of the integration is a semantics of Object-Z classes identical to that of CSP processes. This allows classes specified in Object-Z to he used directly within the CSP part of the specification. In addition to specification, we also discuss refinement and verification in this model. The common semantic basis enables a unified method of refinement to be used, based upon CSP refinement. To enable state-based techniques to be used fur the Object-Z components of a specification we develop state-based refinement relations which are sound and complete with respect to CSP refinement. In addition, a verification method for static and dynamic properties is presented. The method allows us to verify properties of the CSP system specification in terms of its component Object-Z classes by using the laws of the the CSP operators together with the logic for Object-Z.