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Energy modelling is the process of using mathematical models to develop abstractions and then seek insights into future energy systems. It can be an abstract academic activity. Or, it can insert threads that influence our development. We argue therefore, that energy modelling that provides policy support (EMoPS) should not only be grounded in rigorous analytics, but also in good governance principles. As, together with other policy actions, it should be accountable. Almost all aspects of society and much of its impact on the environment are influenced by our use of energy. In this context, EMoPS can inspire, motivate, calibrate, and ‘post assess’ energy policy. But, such modeling is often undertaken by too few analysts under time and resource pressure. Building on the advances of ‘class leaders’, we propose that EMoPS should reach for practical goals — including engagement and accountability with the communities it involves, and those it will later affect. (We use the term Ubuntu, meaning ‘I am because you are’ to capture this interdependency). We argue that Ubuntu, together with retrievability, repeatability, reconstructability, interoperability and auditability (U4RIA) of EMoPS should be used to signal the beginnings of a new default practice. We demonstrate how the U4RIA principles can contribute in practice using recent modelling of aspirational energy futures by Costa Rica as a case study. This modelling effort includes community involvement and interfaces and integrates stakeholder involvement. It leaves a trail that allows for its auditing and accountability, while building capacity and sustainable institutional memory.

The articles in this special section examine the development and future prospects for the European electrical power industry.

Climate and cryospheric observations have shown that the high Arctic has experienced several decades of rapid environmental change, with warming rates well above the global average. In this study, we address the hypothesis that this climatic warming affects deep, ice-covered lakes in the region by causing abrupt, threshold-dependent shifts rather than slow, continuous responses. Synthetic aperture radar (SAR) data show that lakes (one freshwater and four permanently stratified) on Ellesmere Island at the far northern coastline of Canada have experienced significant reductions in summer ice cover over the last decade. The stratified lakes were characterized by strong biogeochemical gradients, yet temperature and salinity profiles of their upper water columns (5-20 m) indicated recent mixing, consistent with loss of their perennial ice and exposure to wind. Although subject to six decades of warming at a rate of 0.5°C decade -1 , these lakes were largely unaffected until a regime shift in air temperature in the 1980s and 1990s, when warming crossed a critical threshold forcing the loss of ice cover. This transition from perennial to annual ice cover caused another regime shift whereby previously stable upper water columns were subjected to mixing. Far northern lakes are responding discontinuously to climate-driven change via a cascade of regime shifts and have an indicator value beyond the regional scale.

A series of meromictic lakes, stratified fjords and freshwater lakes at the northern limit of the Canadian High Arctic (northern coastline of Ellesmere Island, Nunavut) were sampled at different depths to quantify the presence of cyanobacteria and to describe their molecular diversity. The sampled ecosystems spanned a wide span of physico-chemical conditions, with conductivities ranging from freshwater (0.2 mS . cm-1) to seawater (48 mS . cm-1) and temperatures rang- ing from - 1.91 to 12 °C. Fluorescence microscopy cell counts showed that picocy- anobacteria occurred in high concentrations (103 to 2.5 x 104 cells . ml-1) in the oxic and suboxic zones of all of these waters. Molecular analysis of the 16S rRNA gene using Denaturating Gradient Gel Electrophoresis (DGGE) and clone libraries of samples from 8 different lakes and fjords revealed a low diversity of picocyano- bacteria affiliated to the genus Synechococcus. In total, 132 short sequences from DGGE bands, clones and strains were obtained. Most of the sequences (83 %) clustered in two closely related groups that tend to separate according to saline or freshwater conditions. However, some representatives of each OTU were found in different types of habitat, suggesting some degree of tolerance. These results show that picocyanobacteria are widely distributed under a broad range of physical and chemical conditions in the Arctic environment, and that some genotypes may be specialists that occupy specific habitat types.

We profiled five ice-covered lakes and two ice-covered fiords of Ellesmere Island at the northern limit of High Arctic Canada to examine their environmental characteristics, and to evaluate the long-term limnological consequences of changes in their surrounding landscape through time (landscape evolution). All of the ecosystems showed strong patterns of thermal, chemical, and biological stratification with subsurface temperature maxima from 0.75 to 12.15 °C; conductivities up to 98.1 mS cm–1 (twice that of seawater) in some bottom waters; pronounced gradients in nitrogen, phosphorus, pH, dissolved inorganic and organic carbon, manganese, iron, and oxygen; and stratified photo synthetic communities. These ecosystems form an inferred chronosequence that reflects different steps of landscape evolution including marine embayments open to the sea, inlets blocked by thick sea ice (Disraeli Fiord, Taconite Inlet), perennially ice-capped, saline lakes isolated from the sea by isostatic uplift (Lakes A, C1, C2), and isolated lakes that lose their ice cover in summer. The latter are subject to entrainment of saline water into their upper water column by wind-induced mixing (Lake Romulus; Lake A in 2000), or complete flushing of their basins by dilute snowmelt (Lake C3 and Char Lake, which lies 650 km to the south of the Ellesmere lakes region). This chronosequence illustrates how changes in geomorphology and other landscape properties may influence the limnology of coastal, high-latitude lakes, and it provides a framework to explore the potential impacts of climate change.

We report the synthesis and the functional studies of multiple crown alpha-helical peptides designed to form artificial ion channels. The approach combines the versatility of solid phase peptide synthesis, the conformational predictability of peptidic molecules, and the solution synthesis of crown ethers with engineerable ion-binding abilities. Several biophysical methods were employed to characterize the activity and the mode of action of these crown peptide nanostructures. The 21 residue peptides bearing six 21-EC-7 turned out to facilitate the translocation of ions in a similar fashion to natural ion channels.

The geochemical processes occurring within meromictic Lake A (maxdepth 120 m) on northern Ellesmere Island, Canada, were investigated to determinethe history of the lake and to provide a baseline for future studies. The lake contained seawaterdiluted by freshwater input that had been mixed prior to the lake's isolation from tidalaction. Input of freshwater after isolation of the lake created vertical stratification resultingin the creation of distinct oxic, suboxic and anoxic zones. Dissolved oxygen was present to 13 m,and sulphide beneath 32 m. Manganese and iron cycling dominated the redox chemistrybetween these depths. Total manganese concentrations reached 176 μM, higher thanin most other natural stratified lake or marine environments.

Lake A is a meromictic, perennially ice-covered lake located at the northern limit of North America (latitude 83°N, Ellesmere Island, Canada). In early June 1999, only 0.45% of incident photosynthetically available radiation (PAR) was transmitted through its 2-m ice and 0.5-m snow cover. Removal of snow from 12 m2 increased PAR under the ice by a factor of 13 and biologically effective ultraviolet radiation (UVR) by a factor of 16 (from 0.4% to 6.3% of incident). The diffuse attenuation coefficient (Kd) for UVR was substantially lower in the ice than in the underlying freshwater (e.g., 50% lower at 320 nm), indicating the exclusion of chromophoric dissolved organic matter (CDOM) during freeze-up or the subsequent degradation of CDOM retained in the ice. Peak phytoplankton concentrations occurred immediately under the ice, and a broad maximum of photosynthetic sulfur bacteria and associated sulfur particles was observed over the depth interval 20–45 m at

The zooplankton assemblages of Lake A and Disraeli Fjord, northern Ellesmere Island (83°N, 75°W), were surveyed in early summer 1999. In permanently ice-covered Lake A, two glacial relict calanoid copepod species (Drepanopus bungei and Limnocalanus macrurus) were found in the top 30 m. All developmental stages of the more abundant D. bungei were present, whereas only adults of L. macrurus were found. Analysis of gut contents showed that L. macrurus preyed upon the smaller species. A net tow sample of zooplankton from Disraeli Fjord was mainly composed of D. bungei and L. macrurus, along with two marine cyclopoid copepods (Oncaea borealis and Oithona similis). These two zooplankton communities occur within unusual environments that are strongly influenced by perennial ice and snow. They will be subject to major habitat disruption should the current warming trends continue in the north polar region.

Silhouettes of opaque convex objects in orthographic projections were studied in an earlier paper, using a representation on the Gaussian Sphere [1]. A similar argument is applied here to solve for the direct and inverse relations between axisymmetric objects and their silhouettes. Furthermore, a new method for determining object orientation in three dimensions is proposed for such objects, using our analysis of silhouette curvature [1]. Axisymmetric objects are completely determined by a section through their axis of symmetry, which we refer to as the object generator; their silhouettes are symmetric curves in the projection plane. The projection of the object into its silhouette reduces to a transformation between the object generator and the silhouette, which are both planar curves. This paper investigates the conditions under which inversion of this transformation is possible; see Fig. 1. Two cases arise, depending on whether or not the tilt is known between the axis of the object and the projection plane. The derivations summarized here apply to a large class of axisymmetric objects, including non-convex objects. The presentation will be accompanied by a large number of computer generated examples which illustrate various aspects of the theories we developed.

In this paper, an experimental model-based vision system recognizing silhouettes of 3-D objects is described. The system uses local constraints to prune a tree of pairings between image features and model features, then performs a complete verification for each remaining hypothesis. Recognition based on local constraints has been reported by Grimson and Lozano-Perez for matching 2-D measurements to 2-D models, and for matching 3-D measurements to 3-D models [1]. The system described in this paper matches 2-D silhouette measurements to 3-D object models.

In this paper, we show that a one-dimensional or multi-dimensional sequence is uniquely specified under mild restrictions by its Fourier transform amplitude (magnitude and one bit of phase information). In addition, we develop a numerical algorithm to reconstruct a one-dimensional or multi-dimensional sequence from its Fourier transform amplitude. Reconstruction examples obtained using this algorithm are also provided.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.