2D qualitative shape matching applied to ceramic mosaic assembly

A theory of shape recognition of 2D objects and its application in the ceramic industry for intelligent automation of the mosaic mural assembly process are presented in this paper. This theory qualitatively describes the shapes of the objects, considering: (i) shape boundary characteristics, such as angles, relative length, concavities, and curvature; and (ii) their color and size. The shapes to be recognized may be regular or irregular closed polygons, or closed curvilinear figures. Each figure is described as a symbolic character string that contains all its distinctive characteristics. This description is used to determine whether the shape of two figures matches. Then, given a design of a mosaic and given a set of physical ceramic tesserae, an application is developed in order to recognize the tesserae that form the mosaic, thus enabling the intelligent and automated assembly of ceramic mosaics

A survey of qualitative spatial representations

Representation and reasoning with qualitative spatial relations is an important problem in artificial intelligence and has wide applications in the fields of geographic information system, computer vision, autonomous robot navigation, natural language understanding, spatial databases and so on. The reasons for this interest in using qualitative spatial relations include cognitive comprehensibility, efficiency and computational facility. This paper summarizes progress in qualitative spatial representation by describing key calculi representing different types of spatial relationships. The paper concludes with a discussion of current research and glimpse of future work

Strong subadditivity and the covariant holographic entanglement entropy formula

Headrick and Takayanagi showed that the Ryu-Takayanagi holographic entanglement entropy formula generally obeys the strong subadditivity (SSA) inequality, a fundamental property of entropy. However, the Ryu-Takayanagi formula only applies when the bulk spacetime is static. It is not known whether the covariant generalization proposed by Hubeny, Rangamani, and Takayanagi (HRT) also obeys SSA. We investigate this question in three-dimensional AdS-Vaidya spacetimes, finding that SSA is obeyed as long as the bulk spacetime satisfies the null energy condition. This provides strong support for the validity of the HRT formula.Comment: 38 page

Holographic entanglement renormalisation for fermionic quantum matter: geometrical and topological aspects

On performing a sequence of renormalisation group (RG) transformations on a system of two-dimensional non-interacting Dirac fermions placed on a torus, we demonstrate the emergence of an additional spatial dimension arising out of the scaling of multipartite entanglement. The renormalisation of entanglement under this flow exhibits a hierarchy across scales as well as number of parties. Geometric measures defined in this emergent space, such as distances and curvature, can be related to the RG beta function of the coupling $g$ responsible for the spectral gap. This establishes a holographic connection between the spatial geometry of the emergent space in the bulk and the entanglement properties of the quantum theory lying on its boundary. Depending on the anomalous dimension of the coupling $g$, three classes of spaces (bounded, unbounded and flat) are generated from the RG. We show that changing from one class to another involves a topological transition. By minimising the central charge of the conformal field theory describing the noninteracting electrons under the RG flow, the RG transformations are shown to satisfy the $c-$theorem of Zamolodchikov. This is shown to possess a dual within the emergent geometric space, in the form of a convergence parameter that is minimised at large distances. In the presence of an Aharonov-Bohm flux, the entanglement gains a geometry-independent piece which is shown to be topological, sensitive to changes in boundary conditions, and can be related to the Luttinger volume of the system of electrons. In the presence of a strong transverse magnetic field, the system becomes insulating and Luttinger's theorem does not hold. We show instead that the entanglement contains a term that can be related to the Chern numbers of the quantum Hall states. This yields a relation between the topological invariants of the metallic and the quantum Hall systems.Comment: 41 pages, 16 figure

Integrated material practice in free-form timber structures

Integrated material practice in free-form timber structures is a practice-led research project at CITA (Centre for IT and Architecture) that develops a digitally-augmented material practice around glue-laminated timber. The project is part of the InnoChain ETN and has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642877. The advent of digital tools and computation has shifted the focus of many material practices from the shaping of material to the shaping of information. The ability to process large amounts of data quickly has made computation commonplace in the design and manufacture of buildings, especially in iterative digital design workflows. The simulation of material performance and the shift from models as representational tools to functional ones has opened up new methods of working between digital model and physical material. Wood has gained a new relevance in contemporary construction because it is sustainable, renewable, and stores carbon. In light of the climate crisis and concerns about overpopulation, and coupled with developments in adhesives and process technology, it is returning to the forefront of construction. However, as a grown and heterogeneous material, its properties and behaviours nevertheless present barriers to its utilization in architecturally demanding areas. Similarly, the integration of the properties, material behaviours, and production constraints of glue-laminated timber (glulam) assemblies into early-stage architectural design workflows remains a challenging specialist and inter-disciplinary affair. Drawing on a partnership with Dsearch – the digital research network at White Arkitekter in Sweden – and Blumer Lehmann AG – a leading Swiss timber contractor – this research examines the design and fabrication of glue-laminated timber structures and seeks a means to link industrial timber fabrication with early-stage architectural design through the application of computational modelling, design, and an interrogation of established timber production processes. A particular focus is placed on large-scale free-form glulam structures due to their high performance demands and the challenge of exploiting the bending properties of timber. By proposing a computationally-augmented material practice in which design intent is informed by material and fabrication constraints, the research aims to discover new potentials in timber architecture. The central figure in the research is the glulam blank - the glue-laminated near-net shape of large-scale timber components. The design space that the blank occupies - between sawn, graded lumber and the finished architectural component - holds the potential to yield new types of timber components and new structural morphologies. Engaging with this space therefore requires new interfaces for design modelling and production that take into account the affordances of timber and timber processing. The contribution of this research is a framework for a material practice that integrates processes of computational modelling, architectural design, and timber fabrication and acts as a broker between domains of architectural design and industrial timber production. The research identifies four different notions of feedback that allow this material practice to form

Moments in Time

It has been suggested that perception and action can be understood as evolving in temporal epochs or sequential processing units. Successive events are fused into units forming a unitary experience or “psychological present.” Studies have identified several temporal integration levels on different time scales which are fundamental for our understanding of behavior and subjective experience. In recent literature concerning the philosophy and neuroscience of consciousness these separate temporal processing levels are not always precisely distinguished. Therefore, empirical evidence from psychophysics and neuropsychology on these distinct temporal processing levels is presented and discussed within philosophical conceptualizations of time experience. On an elementary level, one can identify a functional moment, a basic temporal building block of perception in the range of milliseconds that defines simultaneity and succession. Below a certain threshold temporal order is not perceived, individual events are processed as co-temporal. On a second level, an experienced moment, which is based on temporal integration of up to a few seconds, has been reported in many qualitatively different experiments in perception and action. It has been suggested that this segmental processing mechanism creates temporal windows that provide a logistical basis for conscious representation and the experience of nowness. On a third level of integration, continuity of experience is enabled by working memory in the range of multiple seconds allowing the maintenance of cognitive operations and emotional feelings, leading to mental presence, a temporal window of an individual’s experienced presence

Object-agnostic Affordance Categorization via Unsupervised Learning of Graph Embeddings

Acquiring knowledge about object interactions and affordances can facilitate scene understanding and human-robot collaboration tasks. As humans tend to use objects in many different ways depending on the scene and the objects’ availability, learning object affordances in everyday-life scenarios is a challenging task, particularly in the presence of an open set of interactions and objects. We address the problem of affordance categorization for class-agnostic objects with an open set of interactions; we achieve this by learning similarities between object interactions in an unsupervised way and thus inducing clusters of object affordances. A novel depth-informed qualitative spatial representation is proposed for the construction of Activity Graphs (AGs), which abstract from the continuous representation of spatio-temporal interactions in RGB-D videos. These AGs are clustered to obtain groups of objects with similar affordances. Our experiments in a real-world scenario demonstrate that our method learns to create object affordance clusters with a high V-measure even in cluttered scenes. The proposed approach handles object occlusions by capturing effectively possible interactions and without imposing any object or scene constraints

A Multilevel Road Alignment Model for Spatial-Query-by-Sketch

A sketch map represents an individual’s perception of a specific location. However, the information in sketch maps is often distorted and incomplete. Nevertheless, the main roads of a given location often exhibit considerable similarities between the sketch maps and metric maps. In this work, a shape-based approach was outlined to align roads in the sketch maps and metric maps. Specifically, the shapes of main roads were compared and analyzed quantitatively and qualitatively in three levels pertaining to an individual road, composite road, and road scene. An experiment was performed in which for eight out of nine maps sketched by our participants, accurate road maps could be obtained automatically taking as input the sketch and the metric map. The experimental results indicate that accurate matches can be obtained when the proposed road alignment approach Shape-based Spatial-Query-by-Sketch (SSQbS) is applied to incomplete or distorted roads present in sketch maps and even to roads with an inconsistent spatial relationship with the roads in the metric maps. Moreover, highly similar matches can be obtained for sketches involving fewer roads

RNA and glia at the Drosophila neuromuscular junction: importance for synaptic plasticity

Glial cells are essential components of both human and invertebrate nervous systems, including in the fruit fly, Drosophila melanogaster. Historically, research has focused more on neurons, with glia and their role in synaptic plasticity being somewhat overlooked. It is generally accepted that synaptic plasticity requires messenger ribonucleic acid (mRNA) and proteins localising at synapses, but the role of glia and mRNA localisation within glia in this process has been comparatively overlooked, despite the knowledge of their close association with synapses. In recent research from the Davis laboratory, high-resolution microscopy was utilised to investigate mRNA and protein expression patterns in the larval nervous system. One common single molecule fluorescence in situ hybridisation (smFISH) probe was designed against the Yellow Fluorescent Protein (YFP) mRNA sequence of 200 Drosophila YFP fusion lines, allowing for the simultaneous detection of the reporter YFP protein and its mRNA within them. This study identified 19 mRNAs believed to be localised in the neuromuscular junction (NMJ) glia. This thesis aims to determine if these mRNAs and their corresponding proteins are indeed in the NMJ glial cells protrusions and if they play a role in regulating synaptic plasticity of the nearby motor neurons. In Chapter 3, I verified that mRNAs of 18 of these transcripts are localised in the NMJ glial protrusions. Some were predominantly glia-specific, while others were also found in surrounding muscle. In Chapter 4, I evaluated the effects of knocking down these 18 mRNAs in glia using an RNA interference (RNAi) candidate screen. Some knockdowns led to NMJ defects, anatomical abnormalities, and, in a few cases, lethality. A crawling impairment phenotype was observed only in the Lachesin (Lac)-RNAi larvae, making Lac a gene of significant interest. In Chapter 5, I investigated the role of Lac in NMJ glia. Lac mRNA localises to specific and targeted NMJ glial structures, while in Lac-RNAi NMJs, the glial projections are disordered and aimless. I determined that the area occupied by Lac::YFP protein decreases after an assay which induces synaptic plasticity, similarly to glial area in control NMJs, and the axon terminal projection area stays constant. In Lac-RNAi larvae, the glial area does not decrease, and the neuronal area increases, suggesting a zero-sum game where the glial and neuronal projection areas at the NMJ exist in a conditional equilibrium. Lac mRNA preferentially associates with the glial and Blood-Brain Barrier (BBB) areas of the NMJ, and the knockdown of Lac in the subperineurial glia, which form the BBB in Drosophila, causes the most severe phenotype of all glial subtypes when comparing to the knockdown in all glia. Lac deficiency at the periphery of NMJ glial cells resulting in aberrant glial cell morphology could lead to altered synaptic plasticity in motor neurons and result in aberrant locomotor behaviour due to disruptions in glia-neuron communication, the BBB function and maintenance, altered neurotransmitter homeostasis, and changes in synaptic strength. In summary, my thesis offers evidence suggesting that glial cell projections closely associated with synapses actively participate in the regulation of the synaptic plasticity happening at these synapses, and such control might be exerted through mRNA localisation of specific transcripts to the glial periphery. I anticipate that this thesis could serve as a valuable reference for subsequent studies on other proteins whose mRNAs might be localised to the glial periphery, possibly specifically ones related to BBB maintenance and formation

Advancing Spatiotemporal Research of Visitor Travel Patterns Within Parks and Protected Areas

Recent technological advances have made it possible to more accurately understand visitor travel patterns and their associated impacts. These advancements help to: accumulate voluminous data sets, collect alternative location data similar to GPS data, conduct spatiotemporal inferential statistics, and advance spatiotemporal visualizations. However, investigations of visitor travel patterns have not kept pace with recent technological advancements. Therefore, the purpose of this dissertation was to advance spatiotemporal research of visitor travel patterns within parks and protected areas by leveraging new technologies. The studies reported in this dissertation were designed to begin filling this gap, and include results from research conducted at: 1) Theodore Roosevelt National Park to identify which spatiotemporal variables are the most important to managers for understanding visitor travel patterns; 2) Hawai’i Volcanoes National Park to identify air tour travel patterns; and 3) the Bonneville Salt Flats to understand visitor travel patterns in a dispersed recreation setting that lacks organizational infrastructure. These three independent but conceptually linked studies were designed to inform our understanding of visitor travel patterns within parks and protected areas. This information is important so that park managers: a) understand how space and time influence visitor routes; and b) have relevant information to continue to conserve the biophysical resource while providing opportunities for quality visitor experiences. Results from the study at Theodore Roosevelt National Park showed that managers identified three temporal variables as being the most important towards understanding visitor travel patterns. These variables were analyzed to determine time allocation and vehicle speed patterns. Results from the study at Hawai’i Volcanoes National Park determined air tour travel patterns and which terrestrial attraction areas were the most affected by air tours. The study at the Bonneville Salt Flats identified potential areas of conflict and designed areas recommended for monitoring. Overall, this dissertation contributes to further understanding of visitor travel patterns, which provides information for managers to continue conserving parks and protected areas for the benefit of society