Map-A-Mole: Greenspace Area Influences the Presence and Abundance of the European Mole Talpa europaea in Urban Habitats

The European mole Talpa europaea is common across much of Britain. It has a unique fossorial lifestyle, and evidence of its presence is readily identified through the presence of characteristic molehills. Although molehills are often a common sight in urban greenspaces, moles are remarkably understudied, with very few studies to date exploring the urban ecology of moles. Here, we investigate if factors such as greenspace (largely urban parks and playing fields) area, intensity of management, distance to nearest patch, amount of time the patch had been isolated from other green patches, and the amount of urbanization (constructed surfaces) surrounding the patch, influence the distribution and abundance of urban moles. Mole signs (hills and surface runs) were counted in all discrete urban greenspaces (excluding domestic gardens and one private golf course) within an 89.5 km2 area in the UK town of Reading. We found that 17 out of 59 surveyed sites contained moles, with their presence being recorded in greenspaces with a minimum patch area of approximately 0.1 km2 (10 ha). Where present, the abundance of mole territories in the greenspaces was associated with both the area of greenspace and degree of urbanization within 150 m of the patch boundary. While the former was not surprising, the latter outcome may be a consequence of sites with an increased risk of flooding being home to fewer moles, and the surrounding area is also less likely to be built upon. This case study highlights how choices made in designing urban green infrastructure will determine which species survive in urban areas long into the future.

Five-Axis Tool Path Generation of Injection Mold Represented by T-Spline Surface

Injection molding is widely used in industries to produce polymeric products. At present, compound NURBS surfaces are commonly used to represent freeform surfaces in mold models. This work uses T-spline surface with extraordinary control points instead of NURBS to represent freeform surfaces in mold models. Compared with NURBS, T-splines’ higher-order continuity facilitates the mold quality control especially at the patch boundary. And, its patch layout information can be utilized for tool path planning. We propose an algorithm to determine the patch processing order and generate nonretraction tool path for T-spline surface models. The tool paths are generated patch by patch using isoparametric strategy. Actual machining and injection molding experiments have been conducted. The result shows the feasibility of the proposed method, and the final product is in good quality.

Localized spatial distributions of disease phases yield long-term persistence of infection

We explore the emergence of persistent infection in two patches where the phases of disease progression of the individuals is given by the well known SIRS cycle modelling non-fatal communicable diseases. We find that a population structured into two patches with significantly different initial states, yields persistent infection, though interestingly, the infection does not persist in a homogeneous population having the same average initial composition as the average of the initial states of the two patches. This holds true for inter-patch links ranging from a single connection to connections across the entire inter-patch boundary. So a population with spatially uniform distribution of disease phases leads to disease extinction, while a population spatially separated into distinct patches aids the long-term persistence of disease. After transience, even very dissimilar patches settle down to the same average infected sub-population size. However the patterns of disease spreading in the patches remain discernibly dissimilar, with the evolution of the total number of infecteds in the two patches displaying distinct periodic wave forms, having markedly different amplitudes, though identical frequencies. We quantify the persistent infection through the size of the asymptotic infected set. We find that the number of inter-patch links does not affect the persistence in any significant manner. The most important feature determining persistence of infection is the disparity in the initial states of the patches, and it is clearly evident that persistence increases with increasing difference in the constitution of the patches. So we conclude that populations with very non-uniform distributions, where the individuals in different phases of disease are strongly compartmentalized spatially, lead to sustained persistence of disease in the entire population.

An explicit formula for a dispersal kernel in a patchy landscape

Integrodifference equations (IDEs) are often used for discrete-time continuous-space models in mathematical biology. The model includes two stages: the reproduction stage, and the dispersal stage. The output of the model is the population density of a species for the next generation across the landscape, given the current population density. Most previous models for dispersal in a heterogeneous landscape approximate the landscape by a set of homogeneous patches, and allow for different demographic and dispersal rates within each patch. Some work has been done designing and analyzing models which also include a patch preference at the boundaries, which is commonly referred to as the degree of bias. Individuals dispersing across a patchy landscape can detect the changes in habitat at a neighborhood of a patch boundary, and as a result, they might change the direction of their movement if they are approaching a bad patch.In our work, we derive a generalization of the classic Laplace kernel, which includes different dispersal rates in each patch as well as different degrees of bias at the patch boundaries. The simple Laplace kernel and the truncated Laplace kernel most often used in classical work appear as special cases of this general kernel. The form of this general kernel is the sum of two different terms: the classic truncated Laplace kernel within each patch, and a correction accounting for the bias at patch boundaries.

Design of Circularly Polarized Modified Minkowski Fractal Based Antenna for UHF RFID Reader Applications

A compact, square shaped microstrip fractal antenna with asymmetrical pairs of T-slits for circularly polarized (CP) radiation and radio frequency identification (RFID) reader applications is proposed and experimentally investigated. Design is based on narrow slit modified Minkowski island fractal geometry. Circular polarization along with size reduction is achieved by inserting four symmetrical pairs of T-slits at the square patch boundary of the single-probe-feed radiator. Proposed geometry is tuned at resonant frequency of 914 MHz by optimization of dimensions of the two T-slits. Compactness of the antenna is achieved by increasing the overall sizes of the slits. Antenna is fabricated on FR4 substrate with a size of 47.2×47.2×1.6 mm3 (0.143λ0 X 0.143λ0 X 0.005λ0) and tested to validate the simulated results. The 3-dB axial-ratio (AR) bandwidth and impedance bandwidth of the proposed antenna design are found to be 7 MHz (911-918 MHz) and 24 MHz (909-933 MHz) respectively. A design equation is develped based on the parametric study that can be used to design a compact antenna with CP for UHF RFID applications covering the frequency range from 887 to 1023 MHz.

Planning Method of Offset Spray Path for Patch considering Boundary Factors

To solve the problem of paint waste at the boundary of the patch when spraying, a planning method of offset spray path considering boundary of the patch is developed. By analyzing the causes of excessive paint waste at the boundary of the patch, a spray path planning method based on boundary curve of the patch is proposed, and the distance between the spray path and the boundary of the patch is optimized to reduce excessive paint waste. According to the allowable range of the spray height and the error range of the coating thickness, the variable range of the spacing distance is established; on this basis, the equal division method of plane intercept line is used to generate the discrete points of the spray path in the length direction of the patch, and a connection algorithm of the discrete points is used to generate the spray path of the patch. The simulation results show that the method can automatically generate a spray path based on the shape of the patch boundary; under the premise of meeting the uniformity requirements of the coating thickness, paint waste can be effectively reduced during spraying.

A microstructural model of reentry arising from focal breakthrough at sites of source-load mismatch in a central region of slow conduction

Regions of cardiac tissue that have a combination of focal activity and poor, heterogeneous gap junction coupling are often considered to be arrhythmogenic; however, the relationship between the properties of the cardiac microstructure and patterns of abnormal propagation is not well understood. The objective of this study was to investigate the effect of microstructure on the initiation of reentry from focal stimulation inside a poorly coupled region embedded in more well-coupled tissue. Two-dimensional discrete computer models of ventricular monolayers (1 × 1 cm) were randomly generated to represent heterogeneity in the cardiac microstructure. A small, central poorly coupled patch (0.40 × 0.40 cm) was introduced to represent the site of focal activity. Simulated unipolar electrogram recordings were computed at various points in the tissue. As the gap conductance of the patch decreased, conduction slowed and became increasingly complex, marked by fractionated electrograms with reduced amplitude. Near the limit of conduction block, isolated breakthrough sites occurred at single cells along the patch boundary and were marked by long cell-to-cell delays and negative deflections on electrogram recordings. The strongest determinant of the site of wavefront breakthrough was the connectivity of the brick wall architecture, which enabled current flow through small regions of overlapping cells to drive propagation into the well-coupled zone. In conclusion, breakthroughs at the size scale of a single cell can occur at the boundary of source-load mismatch allowing focal activations from slow conducting regions to produce reentry. These breakthrough regions, identifiable by distinct asymmetric, reduced amplitude electrograms, are sensitive to tissue architecture and may be targets for ablation.

An Aerodynamic Investigation of an Isolated Rotating Formula 1 Wheel Assembly

The flowfield around a 60% scale rotating Formula 1 tire in contact with the ground in a closed wind tunnel at a Reynolds number of 500,000 was examined computationally and experimentally. The goal of this study was to assess the accuracy of unsteady Reynolds-averaged Navier–Stokes (URANS) equations and confirm the existence of large scale vortical and flow recirculating features. A replica deformable F1 tire model that includes four tire treads and all brake components was used to determine the sensitivity of the wake to cross flow within the tire hub as well as the flow blockage caused by the brake assembly. Several turbulence closures were employed and the one that matched closest to the experimental PIV data was the Reynolds stress model. The variability between the six turbulence closures is shown by comparing velocity profiles, pressure distributions, and vortex eccentricity. The sensitivity of the wake to four different hub geometries, contact patch boundary conditions, multiple reference frame (MRF) rotor and spoke treatment, and time step size are also discussed.

Self-Adjust Terrain LOD Rendering Based on GPU

This paper presents a kind of adaptive rendering algorithm based on the data structure of patch block. It adopts the Tessellation technology and index template technology .The terrain is rendered through the index template technology when it does not need high precision geometric characteristic. The paper presents the calculation model of subdivision coefficient based on the patch boundary and deals with the result of the calculation when the terrain needs high precision geometric characteristic. The result of the experiment indicates the algorithm can improve the rate of frame and the effect is more reality. The terrain of higher detail will be rendered when we input more rough grids.