From Grids to Places

Hafting et al. (2005) described grid cells in the dorsocaudal region of the medial enthorinal cortex (dMEC). These cells show a strikingly regular grid-like firing-pattern as a function of the position of a rat in an enclosure. Since the dMEC projects to the hippocampal areas containing the well-known place cells, the question arises whether and how the localized responses of the latter can emerge based on the output of grid cells. Here, we show that, starting with simulated grid-cells, a simple linear transformation maximizing sparseness leads to a localized representation similar to place fields

Off the Grid

Off the Grid explores the messy relationship between public and private perceptions of our urban spaces, especially the tensions created when lived experience runs up against the physical and conceptual networks of cities: street grids, construction tape, and property lines. Incorporating different modes of spatial representation, from cartographic diagrams to isometric illustrations and Renaissance perspectives, this exhibition examines the role drawing plays in how we conceptualize the divisions and definitions of everyday space. The drawings engage the often overlooked detritus of city life, from layers of old graffiti to overgrown dirt piles and unmoored electrical wiring, that complicate our understanding of how urban space is actually used. Drawn from the spaces surrounding the artist’s daily routine, Off the Grid investigates the potential of a subjective cartography to tell a more complete story about the places we inhabit

Node and Place, a study on the spatial process of railway terminus area redevelopment in central London

Bertolini and Spit (1998) have argued that any significant transport node should ideally also be a significant place in the city. However, this rarely seems to be the case, and the resolution of this disparity, which they refer to as the 'node-place' problem, in practice means redesigning what are currently regional-to-local transport nodes to also function as local pedestrian nodes. This is a complex design task, made more difficult by the fact that termini, although often located in strategic inner urban areas, are also frequently scarred by railway structures and adjacent to large wastelands or blighted neighbourhoods. Not surprisingly, there are as yet few success stories, and conversely many cases where attempts to address this problem through design have fallen below expectations. This problem, of converting railway termini and their surrounding areas into urban places, is the subject of this thesis. The argument proposes that the ‘node-place’ problem is fundamentally a spatial one. Using the methodology of space syntax, together with Hillier's compound theories of how vibrant urban places are progressively formed by the influence of the urban grid on natural movement (Hillier et al 1993 ), and the subsequent influence this has on land use patterns (Hillier 1996 ) and centre formation (Hillier 2000 ), the thesis investigates the spatial structure and functioning of eleven mainline railway terminus areas in central London. This is undertaken through a series of studies of increasing precision: historical figure-ground analyses of station areas; syntactic analysis of station contexts and the influence of the station on that context; detailed observation of movement patterns and rates in station contexts; and finally the synthesis of all data types into a single picture. On the basis of the results of these studies, it is argued that the key to the successful creation of an urban place out of a transport node is the same as that which prevails in cities in general; namely that spatial configuration is critical, and that the spaces inside and outside railway termini have to become an 'integrated part' of the local system of pedestrian movement. In order to achieve this, space has to be re-engineered to overcome the current tendency of stations to work as urban 'negative attractors' through the effect of the large blockages they impose on the development of local patterns of natural movement, in spite of the station being in itself a 'point attractor'. A node can become a place when it also becomes a 'configurational attractor' in the local network

Memory grids: Forgetting East Berlin in Krass Clement’s Photobook Venten på i går. Auf Gestern warten (2012)

Memory grids: Forgetting East Berlin in Krass Clement’s Photobook Venten på i går. Auf Gestern warten (2012)In the article, I argue that by means of qualities intrinsic to the medium of the photobook, the renowned Danish photographer Krass Clement (b. 1946) constructs a complex narration, which, on the one hand, seeksmeta-refl ection on the relationships between photography, memory, and the perception of reality, and, on the other, explores the post-GDR condition of Berlin and Germany. Venten på i går. Auf Gestern warten (Danish and German for “Waiting for yesterday”) includes both old and contemporary images, in both colour and black-and-white, but the book is neither (n)ostalgic nor documentary. Rather, I insist that Clement’s project epitomizes memory work and that its guiding principle can be understood through Rosalind Krauss’ concept of the grid. Th e grid is here inseparable from photography’s relation to memory and reality. I explore how the dialectics between remembering and forgetting, inherent to photography, is enacted by the book, and how it foregrounds the opaqueness rather than the transparency of the medium and perception. I also present how the universe constructed by Clement unfolds within the three temporal dimensions suggested in the title of the book: a present (post-ideological) suspension between the future and the past

Microscale Fluid Behavior during Cryo-EM Sample Blotting

Blotting has been the standard technique for preparing aqueous samples for single-particle electron cryo-microscopy for over three decades. This technique removes the excess solution from a transmission electron microscope grid by pressing absorbent filter paper against the specimen before vitrification. However, this standard technique produces vitreous ice with inconsistent thickness from specimen to specimen and from region to region within the same specimen, the reasons for which are not understood. Here, high-speed interference contrast microscopy is used to demonstrate that the irregular pattern of fibers in the filter paper imposes tortuous, highly variable boundaries during the removal of excess liquid from a flat, hydrophilic surface. As a result, aqueous films of nonuniform thickness are formed while the filter paper is pressed against the substrate. This pattern of nonuniform liquid thickness changes again after the filter paper is pulled away, but the thickness still does not become completely uniform. We suggest that similar topographical features of the liquid film are produced during the standard technique used to blot EM grids and that these manifest in nonuniform ice after vitrification. These observations suggest that alternative thinning techniques, which do not rely on direct contact between the filter paper and the grid, may result in more repeatable and uniform sample thicknesses

Qualitative modelling and analysis of regulations in multi-cellular systems using Petri nets and topological collections

In this paper, we aim at modelling and analyzing the regulation processes in multi-cellular biological systems, in particular tissues. The modelling framework is based on interconnected logical regulatory networks a la Rene Thomas equipped with information about their spatial relationships. The semantics of such models is expressed through colored Petri nets to implement regulation rules, combined with topological collections to implement the spatial information. Some constraints are put on the the representation of spatial information in order to preserve the possibility of an enumerative and exhaustive state space exploration. This paper presents the modelling framework, its semantics, as well as a prototype implementation that allowed preliminary experimentation on some applications.Comment: In Proceedings MeCBIC 2010, arXiv:1011.005

Wildfire: distributed, Grid-enabled workflow construction and execution

BACKGROUND: We observe two trends in bioinformatics: (i) analyses are increasing in complexity, often requiring several applications to be run as a workflow; and (ii) multiple CPU clusters and Grids are available to more scientists. The traditional solution to the problem of running workflows across multiple CPUs required programming, often in a scripting language such as perl. Programming places such solutions beyond the reach of many bioinformatics consumers. RESULTS: We present Wildfire, a graphical user interface for constructing and running workflows. Wildfire borrows user interface features from Jemboss and adds a drag-and-drop interface allowing the user to compose EMBOSS (and other) programs into workflows. For execution, Wildfire uses GEL, the underlying workflow execution engine, which can exploit available parallelism on multiple CPU machines including Beowulf-class clusters and Grids. CONCLUSION: Wildfire simplifies the tasks of constructing and executing bioinformatics workflows