This paper introduces research currently under development in the Digital Architectonics Research Group of the Department of Architecture & Civil Engineering at the University of Bath, UK. This research aims to develop a software framework for the application of subdivision surface techniques to the modeling of complex 3D building forms. By incorporating both structural and environmental optimization algorithms into the framework, a "concurrent engineering" approach is adopted, whereby information on the consequences of different design decisions is provided up-front. This results in a tool through which practicing engineers and architects can explore concepts in an informed manner, helping to steer their creativity towards designs with efficiency built-in. The paper introduces the basic software platform and goes on to describe the implementation of subdivision surface modeling, formfinding and optimization techniques. The benefits of combining these capabilities in a single tool are then demonstrated through a case-study, and the future direction of the research is discussed.

Let f be a C1 function defined over Rn and definable in a given o-minimal structure M expanding the real field. We prove here a gradient-like inequality at infinity in a neighborhood of an asymptotic critical value c. When f is C2 we use this inequality to discuss the trivialization by the gradient flow of f in a neighborhood of a regular asymptotic critical level.

Naegleria fowleri is a small free-living amoeboflagellate found in warm water habitats worldwide. The organism is pathogenic to humans, causing fatal primary amoebic meningoencephalitis. When monitoring the environment for the presence of N. fowleri, it is important to reliably differentiate the organism from other closely related but nonpathogenic species. To this end, we have developed species-specific DNA probes for use in the rapid identification ofN. fowlerifrom the environment. Samples were taken from the thermal springs in Bath, England, and cultured for amoebae. Of 84 isolates of thermophilicNaegleriaspp., 10 were identified as N. fowleri by probe hybridization. The identity of these isolates was subsequently confirmed by their specific whole-cell DNA restriction fragment length polymorphisms (RFLPs). One DNA clone was found to contain a repeatedelementthatdetectedchromosomalRFLPsthatwerenotdirectlyvisibleonagarosegels.Thisenabled the further differentiation of strains within geographically defined whole-cell DNA RFLP groups. N. fowleri DNA probes represent a specific and potentially rapid method for the identification of the organism soon after primary isolation from the environment. Naegleriafowleriisasmallfree-livingamoebafoundinwarm freshwater habitats worldwide. The organism is pathogenic to humans, causing primary amoebic meningoencephalitis (PAM) (4). Infection results from the inoculation of the organism into the nasal passages, usually while bathing, and is almost invari- ably fatal (17, 21). It is therefore important to identify sites containingN. fowleriin the interest of preventive public health microbiology. This requires methods that are both accu- rate and reliable for the differentiation of N. fowleri from other closely related thermophilic Naegleria spp. Although not pathogenic, Naegleria lovaniensis resembles N. fowleri in growth at temperatures of up to 458C, cytopathogenicity for tissue culture cells, and antigenicity (35). Although mouse pathogenicitywasoriginallyusedtodifferentiatethespecies(3, 16), the recognition thatNaegleria australiensiswas pathogenic for mice, albeit less so thanN. fowleri, rendered the test non- specific (9). A variety of techniques have been investigated for the iden- tification of N. fowleri. These include serological tests with species-specific monoclonal antibodies (38), isoenzyme elec- trophoretic profiles (10, 19, 27), characterization of DNA re- striction fragment length polymorphisms (RFLPs) (11, 23, 26), and the amplification of unique regions ofN. fowleriDNA by PCR (25, 34). The advantage of isoenzyme and whole-cell RFLP analyses is that they allow the simultaneous identifica- tion of all currently recognized Naegleria species. However, such methods are expensive and time-consuming and require large numbers of amoebae that usually have to be adapted to axenic (bacteria-free) culture for testing. Genomic DNA is a highly complex structure in which spe- cific sequences that uniquely characterize an organism occur. Advances in recombinant DNA technology enable these re- gions to be isolated, cloned in to a suitable vector, and labelled as probes in the detection of homologous sequences in the

Naegleria fowleriis a small free-living amoeba (FLA) found in warm freshwater habitats worldwide. This organism is pathogenic to humans, causing fatal primary amoebic menin- goencephalitis (PAM) (3, 11). During monitoring of the envi- ronment for the presence ofN. fowleri, it is important to reli- ably differentiate this species from other closely related thermophilicNaegleriaspp. (5, 12, 13, 22). Several techniques have been developed for the identifica- tion of N. fowleri. These include species-specific monoclonal antibodies (25), isoenzyme electrophoretic profiles (5, 17), characterization of DNA restriction fragment length polymor- phisms (RFLPs) (6, 12, 15), and PCR. Amplification of repet- itive DNA has been used for the identification of N. fowleri from purified nucleic acids, in crude preparations of infected mouse brains (16), and from environmental cultures (19, 20). Randomly amplified polymorphic DNA typing has been used to differentiate Naegleria spp. and has also been found to de- tect minor variations inN. fowleristrains (24). Potentially, PCR is a highly specific, sensitive, and rapid method for the identification of microbes. Here, we describe the development of a PCR-based protocol for the identifica- tion ofN. fowlerisoon after primary culture isolation from the environment. The organisms used in this study are listed in Table 1. The Naegleriasp. designations reflect recently proposed changes to this genus (8). The culture and extraction of DNAs from these strains were carried out as described previously (12). The N. fowleri-specific chromosomal DNA probe pB2.3 (12) was par- tiallysequencedbyusingtheSequenaseversion2.0kit(United States Biochemical Corp., Cleveland, Ohio) according to the manufacturer's protocol. Forward and reverse PCR primers were designed from the sequence data of the clone. The pB2.3 forward primer (p3f) used in PCR was GCTATCGAATGGA TTCAAGC, and the reverse primer (p3r) was CACTACTCG TGGAAGGCTTA. PCRwasperformedina100-mlvolumeconsistingof13Taq DNA polymerase buffer (10 mM Tris-HCl (pH 9.0), 50 mM KCl, 1.5 mM MgCl2, and 0.1% Triton X-100), 0.2 mM de- oxynucleoside triphosphates (dNTPs), 1 mM (each) each primer, 2.5UofTaqDNApolymerase(PromegaCorp.,Southampton, England), and approximately 100 ng of DNA that had previ- ously been heated at 968C for 5 min. The reaction mixture was overlaid with 100 ml of mineral oil. The standard temperature program was 1 min at 958C, 1 min at 558C, and 1.5 min at 728C for 35 cycles, with afinal 7 min at 728C. A rapid extraction method for the isolation of N. fowleri DNA from trophozoites or cysts taken directly from nonnutri- ent agar plates seeded with the bacteriumKlebsiella edwardsii (NNA-K. edwardsii plates) was developed. A 1-cm area of amoeba growth was swept from the plate with a disposable bacteriological loop. Amoebae were resuspended in 70 m lo f ice-cold PCR lysis solution (10 mlof10 3TaqDNA polymerase buffer, 1 ml of 10-mg/ml proteinase K, and distilled water to 70 ml),overlaidwith100 mlofsterilemineraloil,andincubatedat 608C for 1 h. The tubes were placed in a boiling water bath for 10 min to inactivate the proteinase K and were chilled on ice. Following the addition of dNTPs, primers, and 2.5 U of Taq DNA polymerase to a final volume of 100 ml, PCR was per- formedasdescribedabove.Carewastakenduringsampling,as the carryover of agar was found to be inhibitory to PCR. Amplification products were detected by analyzing 20 mlof PCR mixture on 1.2% agarose-Tris-borate-EDTA gels in the presence of 0.5 mg of ethidium bromide per ml (18). DNAs from gels were transferred to Hybond N nylon membranes (Amersham International, Buckinghamshire, England) for hy- bridization with the pB2.3 plasmid clone labelled with 59-(a- 32 P)dCTP (18). PCR and hybridization studies were also per-

A slowly moving, rod-shaped magnetotactic bacterium was found in relatively large numbers at and below theoxic-anoxictransitionzoneofasemianaerobicestuarinebasin.Unlikeallmagnetotacticbacteriadescribed to date, cells of this organism produce single-magnetic-domain particles of an iron oxide, magnetite (Fe3O4), andanironsulfide,greigite(Fe3S4),withintheirmagnetosomes.Thecrystalshaddifferentmorphologies,being arrowhead or tooth shaped for the magnetite particles and roughly rectangular for the greigite particles, and were coorganized within the same chain(s) in the same cell with their long axes along the chain direction. Because the two crystal types have different crystallochemical characteristics, the findings presented here suggest that the formation of the crystal types is controlled by separate biomineralization processes and that theassemblyofthemagnetosomechainiscontrolledbyathirdultrastructuralprocess.Inaddition,ourresults show that in some magnetotactic bacteria, external environmental conditions such as redox and/or oxygen or hydrogen sulfide concentrations may affect the composition of the nonmetal part of the magnetosome mineral phase.

The viscous Cahn-Hilliard equation arises as a singular limit of the phase-field model of phase transitions. It contains both the Cahn-Hilliard and Allen-Cahn equations as particular limits. The equation is in gradient form and possesses a compact global atUactor 4 comprising heteroclinic orbits between equilibria. Two classes of wmputati0n.m described,. First heteroclinic o&its on the global attractor are computed; by using the viscous Cahn-Hilliard equation to perform a homotopy. these results show that the orbits, md hence the geometry of the atmctors, are remarkably insensitive to whether the Allen-Cahn or Cahn-Hilliard equation is studied. Second, initial-value computations are described; these computations emphasize three differing mechanisms by which interfaces in the equation propagate for the case of very small penalization of interfacial energy Furthermore, convergence to an appropriate free boundary problem is demonstrated numerically.

The use of multi-agent systems (MAS) in health-care domains is increasing. Such agent-mediated medical systems can manage complex tasks and have the potential to adapt gracefully to unexpected events. However, in these kinds of systems the issues of privacy, security and trust are particularly sensitive in relation to matters such as agents' access to patient records, what is acceptable behaviour for an agent in a particular role and the development of trust both between (heterogeneous) agents and between users and agents. To address these issues we propose a formal normative framework, deriving from and developing the notion of an electronic institution. Such institutions provide a framework to define and police norms that guide, control and regulate the behaviour of the heterogeneous agents that participate in the institution. These norms define the acceptable actions that each agent may perform depending on the role or roles it is playing, and clearly specifies the data it may access and/or modify in playing those roles. In this paper, we present the formalization of Carrel, a virtual organization for the procurement of organs and tissues for transplantation purposes, as an electronic institution using the ISLANDER institution specification language as formalizing languages. We demonstrate aspects of the for- malization of such an institution, example fragments in the language used for the textual specifica- tion, and how such formalization can be used as a blueprint in the implementation of the final agent architecture, through techniques such as skeleton generation. # 2003 Elsevier Science B.V. All rights reserved.

Ionospheric imaging is now well established with over 20 years of research having proven the techniques for both scientific studies and radio system planning tools. Many algorithms now use data from the Global Positioning System (GPS). GPS has revolutionised our ability to monitor the entire ionosphere simultaneously on a global scale. However, the vertical resolution of the images and in particular the separation of the topside ionosphere with the plasmasphere remains a challenge. A further issue is the uneven coverage of ground-based receivers across the Earth. After a general introduction to the science, this paper focuses on two issues; first is the determination of the vertical profile in ionospheric imaging and the ionosphere/plasmasphere separation. A new approach to the determination of the basis functions is discussed that takes into account the plasma behaviour along the magnetic field. Secondly the sparsity of data over certain regions of the Earth and the challenges of producing images with a consistent and reliable resolution standard is considered. Future improvements in both of these areas and the science expected with new low-Earth orbit satellites are discussed.

We study the parabolic Anderson problem, i.e., the heat equation @tu = u + u on (0;1) Zd with independent identically distributed random potential f (z): z 2 Zdg and localised initial condition u(0; x) = 0(x). Our interest is in the long-term behaviour of the random total mass U(t) = P z u(t; z) of the unique non-negative solution in the case that the distribution of (0) is heavy tailed. For this, we study two paradigm cases of distributions with innite moment generating functions: the case of polynomial or Pareto tails, and the case of stretched exponential or Weibull tails. In both cases we nd asymptotic expansions for the logarithm of the total mass up to the rst random term, which we describe in terms of weak limit theorems. In the case of polynomial tails, already the leading term in the expansion is random. For stretched exponential tails, we observe random uctuations in the almost sure asymptotics of the second term of the expansion, but in the weak sense the fourth term is the rst random term of the expansion. The main tool in our proofs is extreme value theory.