Distance Profiles Research Articles

Rate $(n-1)/n$ Systematic Memory Maximum Distance Separable Convolutional Codes

A systematic convolutional encoder of rate (n-1)/n and maximum memory D generates a code of free distance at most V = D + 2 and, at best, a column distance profile (CDP) of [2,3, .. . , D]. A code is memory maximum distance separable if it possesses this CDP. Applied on a communication channel over which packets are transmitted sequentially and which loses (erases) packets randomly, such a code allows the recovery from any pattern of j erasures in the first j n-packet blocks for j <; V, with a delay of exactly j blocks counting from the first non-corrected erasure. This paper addresses the problem of finding the largest V for which a systematic rate (n - 1)/n code over a given field exists, for given n. In particular, constructions for rate (p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> - 1)/p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> and V equal to 3 over GF(p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> ) and rate (2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m-1</sup> -1)/2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m-1</sup> and V equal to 4 over GF(2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> ) are presented, which provide optimum values of V in their respective cases. A search algorithm is also developed, which produces new codes for V for field sizes 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> ≤ 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> . Using a complete search version of the algorithm, the maximum value of V, and codes that achieve it, are determined for all code rates ≥ 1/2 and every field size GF(2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> ) for m ≤ 5 (and for some rates for m = 6).

Temperature effect on the structure and conformational fluctuations in two zinc knuckles from the mouse mammary tumor virus

Zinc fingers are small protein domains in which zinc plays a structural role, contributing to the stability of the zinc–peptide complex. Zinc fingers are structurally diverse and are present in proteins that perform a broad range of functions in various cellular processes, such as replication and repair, transcription and translation, metabolism and signaling, cell proliferation, and apoptosis. Zinc fingers typically function as interaction modules and bind to a wide variety of compounds, such as nucleic acids, proteins, and small molecules. In this study, we investigated the structural properties, in solution, of the proximal and distal zinc knuckles of the nucleocapsid (NC) protein from the mouse mammary tumor virus (MMTV) (MMTV NC). For this purpose, we performed a series of molecular dynamics simulations in aqueous solution at 300 K, 333 K, and 348 K. The temperature effect was evaluated in terms of root mean square deviation of the backbone atoms and root mean square fluctuation of the coordinating residue atoms. The stability of the zinc coordination sphere was analyzed based upon the time profile of the interatomic distances between the zinc ions and the chelator atoms. The results indicate that the hydrophobic character of the proximal zinc finger is dominant at 333 K. The low mobility of the coordinating residues suggests that the strong electrostatic effect exerted by the zinc ion on its coordinating residues is not influenced by the increase in temperature. The evolution of the structural parameters of the coordination sphere of the distal zinc finger at 300 K gives us a reasonable picture of the unfolding pathway, as proposed by Bombarda and coworkers (Bombarda et al., 2005), which can predict the binding order of the four conserved ligand-binding residues. Our results support the conclusion that the structural features can vary significantly between the two zinc knuckles of MMTV NC.

A Reproducible Framework for Visualizing Demographic Distance Profiles in US Metropolitan Areas

Distance profiles have long been used in urban demography to explore how demographic characteristics of metropolitan areas vary by distance from their urban cores. Distance profile visualizations graphically illustrate these relationships and are useful in exploratory demographic data analysis of urban areas. The purpose of this article is to demonstrate how to build distance profile visualizations reproducibly within R, a free and open-source programming language and data analysis environment. The approach to distance profile visualization in this article involves the graphical display of a smoothed relationship between the location quotient of a demographic group for a metropolitan Census tract and the distance between the tract centroid and its respective urban core. Data acquisition, analysis, and visualization are all handled in R. The tidycensus, sf, and ggplot2 R packages are featured in this framework. Distance profile visualizations for educational attainment are used as illustrative examples, and reveal how the geography of metropolitan educational attainment varies both over time and across different types of metropolitan areas.

Rate-Compatible Tail-Biting Convolutional Codes for M2M Communications

We propose an algorithm to construct a group of rate-compatible tail-biting convolutional codes (RC-TBCCs) with consistently good frame error rate performance for both short and long information lengths. The algorithm considers the free distance property and the minimum distance profile of a TBCC jointly. We construct a group of RC-TBCCs with code rates $1/n$ , $3\leq n\leq 12$ . Numerical results show that the constructed RC-TBCCs have better frame error rate performance than the TBCCs used in LTE standards for various information lengths and code rates.

Weld bead recognition using laser vision with model-based classification

Abstract Weld bead recognition is important for providing information for automatic control of welding process and also for post-weld inspection. Bead geometry profiles can be measured by a laser-line profile sensor projecting a laser line onto the welding surface and receiving the reflection to calculate the height of the surface. As the bead is usually very small, it may be easily covered by the sensor noise or distorted by the bending of the work pieces after welding. In addition, it is difficult to estimate the parameters of bead width and bead height while moving the laser sensor to cover a 3D surface, since the movement may cause unstable measurements. This work investigates using a model-based classification method to automatically segment the bead from the welding surface regardless of the distance and the angle of the scanner to the welding surface. It firstly uses a polynomial model together with the Expectation-Maximisation (EM) algorithm fitting into the distance profiles measured by the laser sensor, and then automatically removes the surface curvature. Consequently the shape of the bead can be easily extracted from the welding surface by applying a small value of threshold depending on the noise level of the data. Experimental results show that the Butt welding bead parameters of bead width and height can be extracted successfully. The method is robust to the bending of the welding surface and the unstable movement of the laser sensor.

Multiscale Measures of Population: Within- and between-City Variation in Exposure to the Sociospatial Context

Appreciating spatial scale is crucial for our understanding of the sociospatial context. Multiscale measures of population have been developed in the segregation and neighborhood effects literatures, which have acknowledged the role of a variety of spatial contexts for individual outcomes and intergroup contacts. Although existing studies dealing with sociospatial inequalities increasingly explore the effects of spatial scale, there has been little systematic evidence on how exposure to sociospatial contexts changes across urban space, both within and between cities. This article presents a multiscale approach to measuring potential exposure to others. Using individual-level register data for the full population of The Netherlands and an exceptionally detailed multiscalar framework of bespoke neighborhoods at 101 spatial scales, we measured the share of non-Western ethnic minorities for three Dutch cities with different urban forms. We created individual and cumulative distance profiles of ethnic exposure, mapped ethnic exposure surfaces, and applied entropy as a measure of scalar variation to compare potential exposure to others in different locations both within and between cities. The multiscale approach can be implemented for examining a variety of social processes, notably segregation and neighborhood effects.

Effect of elliptical vibration trajectories on grating structure formation and its application in structural coloration

Structural coloration, which utilizes the optical interactions between the periodic nanostructures and visible light to render iridescent or non-iridescent colors, has been a fascinating research topic in recent years. The rendering performance of artificial structural color is subject to the nanofabrication capability and structure accuracy. In this paper, an innovative elliptical vibration texturing method has been introduced for fast generation of periodic controllable grating structures, which can be utilized as reflective gratings for rendering iridescent structural color effects. Firstly, the effect of different elliptical vibration trajectories on the formation of grating structure is theoretically analyzed and experimentally verified. Secondly, the structural coloration based on the grating formation is demonstrated; and the relationship between the color effect and grating profiles is studied. Specifically, different elliptical trajectories, which are commonly used in vibration-assisted machining, are generated by a newly-proposed non-resonant vibration cutting tool and employed for the generation of periodic grating structures. An analytical model for the prediction of grating profile is established, which takes into account the tool vibration trajectory and tool geometry. It is found that the orientation and periodic distance of grating structures can be precisely controlled, while the cross-section profile has a strong dependence on the vibration trajectories. The results indicate that tilted elliptical trajectories with at least a 3 μm vibration amplitude in the depth-of-cut (DOC) direction are favorable for the generation of high aspect-ratio grating structures. An insufficient DOC vibration amplitude (less than 3 µm) leads to the reduced effective chip thickness and unstable plastic chip removal. The elastic recovery effect becomes significant and deteriorates the formation of desired grating structures. Subsequently, the iridescent color effects are demonstrated and compared between samples produced with different tool vibration trajectories. The hue and brightness of induced colors are independently determined by the periodic distance and cross-section profiles of generated grating structures. The proposed non-resonant vibration texturing method provides a new manufacturing method for realizing structural colors in addition to the existing nanofabrication processes.

Analytical Miss Rate Calculation of L2 Cache from the RD Profile of L1 Cache

Reuse distance is an important metric for analytical estimation of cache miss rate. To find the miss rate of a particular cache, the reuse distance profile has to be measured for that particular level and configuration of the cache. Significant amount of simulation time and overhead can be reduced if we can find the miss rate of higher level cache like L2 cache from the RD profile with respect to a lower level cache (i.e., cache that is closer to the processor) such as L1. The objective of this paper is to give an analytical method to find the miss rate of L2 cache for various configurations from the RD profile with respect to L1 cache. We consider all three types of cache inclusion policies namely (i) Strictly Inclusive, (ii) Mutually Exclusive and (iii) Non-Inclusive Non-Exclusive policy. We first prove some general results relating the RD profile of L1 cache to that of L2 cache. We use probabilistic analysis for our derivations. We validate our model against simulations, using the multi-core simulator Sniper with the PARSEC and the SPLASH benchmark suites.

Interdiffusion and Atomic Mobilities in fcc Co-Ga and Co-V Alloys

On the basis of Co/Co-10Ga, Co/Co-12Ga, and Co/Co-10V (at.%) diffusion couples, interdiffusion coefficients in the face-centered cubic (fcc) phase of the Co-Ga and Co-V binary systems were investigated in the temperature range between 1273 and 1573 K by means of the den Broeder method. Based on available thermodynamic information, the interdiffusion data were assessed to develop the atomic mobilities for the fcc Co-Ga and Co-V alloys using the DICTRA software package, and their validity was tested by simulating concentration–distance profiles.

Experimental measurements of the interdiffusivities in fcc Co–rich Co–Ti, Co–W and Co–Ti–W systems

Utilizing 8 bulk single–phase diffusion couples together with the electron probe microanalysis technique, the composition–distance profiles of fcc binary Co–Ti and Co–W systems as well as ternary Co–Ti–W system at 1373K were first measured. The measured composition profiles for Co–rich Co–Ti, Co–W and Co–Ti–W systems at 1373K were then adopted to evaluate the corresponding binary and ternary interdiffusivities by using the newly proposed pragmatic numerical inverse method. The comprehensive comparisons between various model–predicted diffusion properties based on the evaluated interdiffusivities due to the pragmatic numerical inverse method, including composition profiles, interdiffusion fluxes and diffusion paths, and the experimental data were conducted to validate their reliability. Moreover, the presently obtained binary and ternary interdiffusivities by the numerical inverse method were further validated by the literature data and the calculated results by using the traditional Sauer–Freise method and Matano–Kirkaldy method.

Anion Layering and Steric Hydration Repulsion on Positively Charged Surfaces in Aqueous Electrolytes.

The molecular structure at charged solid/liquid interfaces is vital for many chemical or electrochemical processes, such as adhesion, catalysis, or the stability of colloidal dispersions. How cations influence structural hydration forces and interactions across negatively charged surfaces has been studied in great detail. However, how anions influence structural hydration forces on positively charged surfaces is much less understood. Herein we report force versus distance profiles on freshly cleaved mica using atomic force microscopy with silicon tips. We characterize steric anion hydration forces for a set of common anions (Cl- , ClO4- , NO3- , SO42- and PO43- ) in pure acids at pH ≈1, where protons are the co-ions. Solutions containing anions with low hydration energies exhibit repulsive structural hydration forces, indicating significant ion and/or water structuring within the first 1-2 nm on a positively charged surface. We attribute this to specific adsorption effects within the Stern layer. In contrast, ions with high hydration energies show exponentially repulsive hydration forces, indicating a lower degree of structuring within the Stern layer. The presented data demonstrates that anion hydration forces in the inner double layer are comparable to cation hydration forces, and that they qualitatively correlate with hydration free energies. This work contributes to understanding interaction processes in which positive charge is screened by anions within an electrolyte.

Travel times and transfers in public transport: Comprehensive accessibility analysis based on Pareto-optimal journeys

Efficient public transport (PT) networks are vital for well-functioning and sustainable cities. Compared to other modes of transport, PT networks feature inherent systemic complexity due to their schedule-dependence and network organization. Because of this, efficient PT network planning and management calls for advanced modeling and analysis tools. These tools have to take into account how people use PT networks, including factors such as demand, accessibility, trip planning and navigability. From the PT user perspective, the common criteria for planning trips include waiting times to departure, journey durations, and the number of required transfers. However, waiting times and transfers have typically been neglected in PT accessibility studies and related decision-support tools. Here, we tackle this issue by introducing a decision-support framework for PT planners and managers, based on temporal networks methodology. This framework allows for computing pre-journey waiting times, journey durations, and number of required transfers for all Pareto-optimal journeys between any origin–destination pair, at all points in time. We visualize this information as a temporal distance profile, covering any given time interval. Based on such profiles, we define the best-case, mean, and worst-case measures for PT travel time and number of required PT vehicle boardings, and demonstrate their practical utility to PT planning through a series of accessibility case studies. By visualizing the computed measures on a map and studying their relationships by performing an all-to-all analysis between 7463 PT stops in the Helsinki metropolitan region, we show that each of the measures provides a different perspective on accessibility. To pave the way towards more comprehensive understanding of PT accessibility, we provide our methods and full analysis pipeline as free and open source software.

Cross-Linking Highly Lubricious Phosphocholinated Polymer Brushes: Effect on Surface Interactions and Frictional Behavior

Poly[2-(methacryloyloxy)ethylphosphorylcholine] (pMPC) brushes provide extremely low friction coefficients up to high compressions, but their use as boundary lubricating layers is limited by the challenge of surface grafting of the chains. Coating by thin layers of cross-linked pMPC hydrogels may provide an attractive alternative. Here we use a surface force balance (SFB) and other techniques to examine the effect of light cross-linking (0.1% cross-linker) on the surface interactions and frictional behavior of grafted-from pMPC brushes on mica, up to physiologically high contact pressures. Atomic force microscopy, X-ray photoelectron spectroscopy, and interferometric surface-excess measurements show little difference between the non-cross-linked (linear) pMPC brushes and the cross-linked brushes prepared under otherwise identical conditions. Normal force–distance profiles between the polymer-bearing surfaces, however, reveal a marked compaction of the unperturbed thickness of the cross-linked brushes rela...

Guiding Locality Optimizations for Graph Computations via Reuse Distance Analysis

This work addresses the problem of optimizing graph-based programs for multicore processors. We use three graph benchmarks and three input data sets to characterize the importance of properly partitioning graphs among cores at multiple levels of the cache hierarchy. We also exhaustively explore a large design space comprised of different parallelization schemes and graph partitionings via detailed simulation to show how much gain we can obtain over a baseline legacy scheme that partitions for the L1 cache only. Our results demonstrate the legacy approach is not the best choice, and that our proposed parallelization / locality techniques can perform better (by up to 20 percent). We then use a performance prediction model based on multicore reuse distance (RD) profiles to rank order the different parallelization / locality schemes in the design space. We compare the best configuration as predicted by our model against the actual best identified by our exhaustive simulations. For one benchmark and data input, we show our model can achieve 79.5 percent of the performance gain achieved by the actual best. Across all benchmarks and data inputs, our model achieves 48 percent of the maximum performance gain. Our work demonstrates a new use case for multicore RD profiles–i.e. as a tool for helping program developers and compilers to optimize graph-based programs.

Limited drug solubility can be decisive even for freely soluble drugs in highly swollen matrix tablets

The aim of this study was to elucidate the importance of potential limited solubility effects for the control of drug release from hydrophilic matrix tablets loaded with a freely water-soluble drug. It is often assumed that the considerable amounts of water penetrating into this type of advanced drug delivery systems are sufficient to rapidly dissolve the entire drug loading, and that limited drug solubility is not playing a role for the control of drug release. Here, we show that this assumption can be erroneous. HPMC/lactose matrix tablets were loaded with 5 to 60% diprophylline (e.g. solubility in 0.1M HCl at 37°C: 235mg/mL), and drug release was measured at low and neutral pH, respectively. A mechanistically realistic mathematical theory was applied, considering drug diffusion in axial and radial direction in the cylindrical matrices and the potential co-existence of dissolved and non-dissolved drug. Importantly, only dissolved drug is available for diffusion. It is demonstrated that during major parts of the release periods, non-dissolved drug excess exists within tablets containing 30% or more diprophylline, despite of the substantial water contents of the systems. This leads to partially almost linear drug concentration distance profiles within the tablets, and reveals a major contribution of limited drug solubility effects to the control of drug release, even in the case of freely water-soluble diprophylline. It can be expected that also in other types of drug delivery systems, e.g. microparticles and implants (containing much less water), limited drug solubility effects play a much more important role than currently recognized.

Region-driven distance regularized level set evolution for change detection in remote sensing images

Change detection is a fundamental task in the interpretation and understanding of remote sensing images. The aim is to partition the difference images acquired from multitemporal satellite images into changed and unchanged regions. Level set method is a promising way for remote sensing images change detection among the existed methods. Unfortunately, re-initialization, a necessary step in classical level set methods is known a complex and time-consuming process, which may limits their practical application in remote sensing images change detection. In this paper, we present an unsupervised change detection approach for remote sensing image based on an improved region-based active contour model without re-initialization. In order to eliminate the process for re-initialization and reduce the numerical errors caused by re-initialization, we describe an improving level set method for remote sensing images change detection. The proposed method introduced a distance regularization term into the energy function which could maintain a desired shape of the level set function and keep a signed distance profile near the zero level set. The experimental results on real multi-temporal remote sensing images demonstrate the advantages of our method in terms of human visual perception and segmentation accuracy.

Influence of normal fault growth and linkage on the evolution of a rift basin: A case from the Gaoyou depression of the Subei Basin, eastern China

ABSTRACT It is widely acknowledged that the growth and linkage of a boundary fault affects the evolution of the accompanying sedimentary basin and exerts a strong influence on its sedimentary characteristics. In this study, we attempt to discuss the evolution of a boundary fault and rift basin by using seismic interpretation, incremental fault throw, and growth rate–distance (G–d) profile, which are more suitable parameters than the expansion index in rift basins where footwall strata are missing because of erosion or a depositional hiatus. Therefore, the Gaoyou depression is taken as an example. The Gaoyou depression is the largest hydrocarbon-bearing depression in the Subei Basin, which is a representative rift basin in eastern China. The depression is bounded to the south by the Jiangdu–Wubao fault zone, which includes the Zhen 1–Wu 1, Zhen 2, and Wu 2 faults. Using high-resolution, three-dimensional seismic data, the Zhen 1–Wu 1 fault can be subdivided into four segments based on its G–d profile: the Shaobo, Fanchuan, Liuwushe, and Liulu segments. Growth rates indicate that the Zhen 1–Wu 1 fault and the Zhen 2 and Wu 2 faults developed successively from the Late Cretaceous to the Miocene during rifting of the Gaoyou depression and that development of the Zhen 2 and Wu 2 faults was controlled by the Zhen 1–Wu 1 fault. The four segments of the Zhen 1–Wu 1 fault were linked with each other by the time the Zhen 2 and Wu 2 faults formed in the Late Paleocene. An evolution model of the Gaoyou depression is set up in this study. Integrating the fault activity with previous sedimentological studies, we suggest that the evolution of the Gaoyou depression was controlled by the Jiangdu–Wubao fault zone rather than by a single fault. Successive slip of the Zhen 1–Wu 1 fault and the Zhen 2 and Wu 2 faults caused subsidence and migration of the depocenters. This study presents a case investigation of the effects of boundary faults on rift basins in eastern China.

Critical lengths of grade in highway design for wind farms

Wind energy as a power source is an attractive alternative to fossil fuels. Globally, an increasing number of wind farms is being planned and constructed. The conditions of highway design indexes for wind farms are unique, and the current design standards are not appropriate for determining the necessary critical lengths of grade. The relative vehicle parameters for aerogenerator transportation are investigated in detail, and the typical design vehicle for aerogenerator transportation is selected. The dynamic characteristics, such as acceleration and deceleration performances, are analysed based on the nominal dynamic, kinematic and operating characteristics of the typical vehicle on wind farm grades and terrain elevation. This study proposes a formulation to obtain the relation between speed and distance travelled for heavier design vehicles, from which speed-gain and speed-drop curves are calculated and drawn. In addition, the total accumulative speed–distance profiles with different gears are also combined. Through an extensive calculation, this paper also provides practitioners with design tables for the maximum critical length of typical design vehicles for large aerogenerator transportation under full load and 80 t load. The research results can serve as a reference for aerogenerator transportation highway design and construction and are helpful for related highway geometric design guidelines.

Artefacts in multimodal imaging of titanium, zirconium and binary titanium-zirconium alloy dental implants: an in vitro study.

To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium-zirconium alloy dental implants. Zirconium, titanium and titanium-zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line-distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. While titanium and titanium-zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium-zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium-zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium-zirconium alloy induced more severe artefacts than zirconium and titanium. MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium-zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting.

Interaction forces and membrane charge tunability: Oleic acid containing membranes in different pH conditions

Oleic acid is known to interact with saturated lipid molecules and increase the fluidity of gel phase lipid membranes. In this work, the thermodynamic properties of mixed monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and oleic acid at the air-water interface were determined using Langmuir isotherms. The isotherm study revealed an attractive interaction between oleic acid and DPPC. The incorporation of oleic acid also monotonically decreased the elastic modulus of the monolayer indicative of higher fluidity with increasing oleic acid content. Using the surface force apparatus, intermembrane force–distance profiles were obtained for substrate supported DPPC membranes containing 30mol% oleic acid at pH5.8 and 7.4. Three different preparation conditions resulted in distinct force profiles. Membranes prepared in pH5.8 subphase had a low number of nanoscopic defects ≤1% and an adhesion magnitude of ~0.6mN/m. A slightly higher defect density of 1–4% was found for membranes prepared in a physiological pH7.4 subphase. The presence of the exposed hydrophobic moieties resulted in a higher adhesion magnitude of 2.9mN/m. Importantly, at pH7.4, some oleic acid deprotonates resulting in a long-range electrostatic repulsion. Even though oleic acid increased the DPPC bilayer fluidity and the number of defects, no membrane restructuring was observed indicating that the system maintained a stable configuration.