Distance Threshold Research Articles

Transcript Engineered Extracellular Vesicles Alleviate Alloreactive Dynamics in Renal Transplantation.

Direct contact of membrane molecules and cytokine interactions orchestrate immune homeostasis. However, overcoming the threshold of distance and velocity barriers, and achieving adhesion mediated immune interaction remain difficult. Here, inspired by the natural chemotaxis of regulatory T cells, multifunctionalized FOXP3 genetic engineeredextracellular vesicles, termed Foe-TEVs, are designed, which display with adhesive molecules, regulatory cytokines, and coinhibitory contact molecules involving CTLA-4 and PD-1, by limited exogenous gene transduction. Foe-TEVs effectively adhere to the tubular, endothelial, and glomerular regions of allogeneic injury in the renal allograft, mitigating cell death in situ and chronic fibrosis transition. Remarkably, transcript engineering reverses the tracking velocity of vesicles to a retained phenotype and enhanced arrest coefficient by a factor of 2.16, directly interacting and attenuating excessive allosensitization kinetics in adaptive lymphoid organs. In murine allogeneic transplantation, immune adhesive Foe-TEVs alleviate pathological responses, restore renal function with well ordered ultrastructure and improved glomerular filtration rate, and prolong the survival period of the recipient from 30.16 to 92.81 days, demonstrating that the delivery of extracellular vesicles, genetically engineered for immune adhesive, is a promising strategy for the treatment of graft rejection.

A Reflection on the Response to Sudden-Onset Disasters in the Post-Pandemic Era: A Graded Assessment of Urban Transportation Resilience Taking Wuhan, China as an Example

The COVID-19 pandemic has led to thinking about the response to sudden-onset disasters, for which the transportation resilience of urban areas is crucial. The purpose of paper is to provide a graded assessment of urban transportation resilience to help city managers target policies and plans. Wuhan, the first city in China to be severely hit by COVID-19, was selected as the case study for this research. Based on an extensive survey of the travel characteristics of residents in central urban areas, the concept of “travel mode shift” was combined to classify residents into four modes, including non-motorized conventional travel, non-motorized over-distance travel, motorized adaptable travel and motorized non-substitutable travel. The potential transportation stoppages in different levels of epidemic impact were then divided into three scenarios, corresponding to each of the city’s three levels of transportation resilience. The concept of MWD (Maximum Willingness Distance) in active travel mode was further developed, which was divided into WMWD (Walking Maximum Willingness Distance) and RMWD (Riding Maximum Willingness Distance). Finally, a hierarchical assessment model of urban transportation resilience is developed based on the MWD distance threshold. Besides, the average income level of urban residents was also included in the assessment system. The following research conclusions were drawn: (1) The degree of transportation resilience in Wuhan showed an “S-curve” relationship with RMWD, with thresholds at RMWD = 2.5 km, 11 km and 23 km respectively. (2) The resilience of transportation in the suburbs of the city was weaker than in the city center, and the gap between the two increases as the RMWD increases, but the share of motorized transportation in short distance trips in the city center was still higher than desirable. (3) The upper-income groups in the city had more flexible travel options, while the lower income groups were less resilient to travel. Based on the results of the study, it is recommended that city managers can identify areas of low resilience and critical distance thresholds that may lead to sudden changes in transportation resilience in the event of a sudden disaster. This will lead to the development of improved policies. The special needs of socially disadvantaged groups should also be taken more into account in this process.

Persistent Transmission of HCV among Men Who Have Sex with Men despite Widespread Screening and Treatment with Direct-Acting Antivirals.

Background: In the Netherlands, unrestricted access to direct-acting antivirals (DAAs) halved the incidence of acute hepatitis C virus (HCV) infections among HIV-infected men who have sex with men (MSM). To develop strategies that can further reduce the spread of HCV, it is important to understand the transmission dynamics of HCV. We used phylogenetic analysis of a dense sample of MSM to provide insight into the impact of unrestricted access to DAAs on HCV transmission in the Netherlands and in Belgium. Methods: We included 89 MSM that were recently infected with HCV genotype 1a in ten Dutch and one Belgian HIV treatment centers. Sequences were generated using next gene sequencing and Sanger sequencing. Maximum likelihood phylogenetic analysis (general time reversible model) was performed on concatenated NS5A and NS5B sequences and a reference set of 389 highly similar control sequences selected from GenBank. A cluster was based on a minimum bootstrap support of 90% and a 3% genetic distance threshold. Results: We found that 78 (88%) of individuals were part of seven major clusters. All clusters included individuals from across the study region, however, different cities were part of different clusters. In three clusters, HIV-negative MSM clustered with sequences from HIV-positive MSM. All clusters that were observed before the introduction of DAAs persisted after unrestricted access to DAAs became available. Conclusion: Recently acquired HCV infections among MSM in the Netherlands and Belgium are strongly clustered and therefore highly suitable for targeted prevention strategies, such as contact tracing and partner notification. Importantly, despite an HCV incidence reduction after high DAA uptake and continuously monitoring, HCV transmission persisted in the same clusters.

The effect of biomass raw material collection distance on energy surplus factor.

The collection radius of biomass raw materials is an important factor affecting the volume of raw materials for energy utilization. At present, it is usually studied based on a single biomass combined heat and power (CHP) plant. However, as the heat transfer threshold of biomass CHP plant is limited, it is necessary to consider the optimal collection radius and biomass raw material allocation under the distribution mode of multiple power plants to improve the overall utilization rate of raw materials. Biomass raw material collection distance threshold (BCDT) refers to the maximum road length between the resource point (that allows the transportation of raw materials to the biomass CHP plant) and the biomass CHP plant. Under the mode of multi-power plant planning, the greater the BCDT is, the more destinations there will be for raw materials to be transported to from the same resource point, and the more flexible the transportation plans and allocation of transportation volumes will be. This also means more raw materials can be ultimately used for energy utilization, which leads to higher transportation cost. Therefore, determining the appropriate BCDT plays a key role in the unified planning of biomass raw materials. Based on the limitation of heat transfer threshold, this paper carries out multi-power plant planning with Fuxin City as the research object. Based on such planning, ArcGIS is used to generate biomass raw material planning schemes with different BCDTs. Then the transportation cost and energy surplus factor (ratio of renewable resource potential to energy demand) of each scheme are calculated and compared. The results show that there is a positive correlation between BCDT and the energy surplus factor. With the increase of BCDT, the growth rate of the energy surplus factor gradually becomes slower. The study also allows to set the utilization threshold of biomass energy utilization capacity and obtain the corresponding BCDT. In order to achieve a higher energy surplus factor, it is recommended that 40km be used as the BCDT when carrying out uniform planning for biomass raw materials. At this time, the utilization of biomass energy utilization capacity is 75%, which can achieve a high degree of energy self-sufficiency and ensure its economic competitiveness.

A variable threshold for recurrence based on local attractor density.

Recurrence plots along with their quantification measures have demonstrated their usefulness for the study of dynamical systems in many fields. The distance threshold for recurrence is a crucial parameter influencing the observed recurrence structures, thus, the related quantification measures, and have been the object of several studies to find its optimal value. We suggest here a definition of recurrence based on the local attractor density to obtain more qualitative recurrence plots capturing the dynamics at different scales without suffering from variations in the tangential motion effect. The method is qualitatively and quantitatively compared with common thresholding methods on different signals. It is shown that the suggested recurrence plot has more uniform line structures and is less sensitive to the threshold parameter. We also present a modification enhancing its robustness to noise.

Smart Vehicle Path Planning Based on Modified PRM Algorithm.

Path planning is a very important step for mobile smart vehicles in complex environments. Sampling based planners such as the Probabilistic Roadmap Method (PRM) have been widely used for smart vehicle applications. However, there exist some shortcomings, such as low efficiency, low reuse rate of the roadmap, and a lack of guidance in the selection of sampling points. To solve the above problems, we designed a pseudo-random sampling strategy with the main spatial axis as the reference axis. We optimized the generation of sampling points, removed redundant sampling points, set the distance threshold between road points, adopted a two-way incremental method for collision detections, and optimized the number of collision detection calls to improve the construction efficiency of the roadmap. The key road points of the planned path were extracted as discrete control points of the Bessel curve, and the paths were smoothed to make the generated paths more consistent with the driving conditions of vehicles. The correctness of the modified PRM was verified and analyzed using MATLAB and ROS to build a test platform. Compared with the basic PRM algorithm, the modified PRM algorithm has advantages related to speed in constructing the roadmap, path planning, and path length.

High proportion of tuberculosis transmission among social contacts in rural China: a 12-year prospective population-based genomic epidemiological study

ABSTRACT Tuberculosis (TB) is more prevalent in rural than urban areas in China, and delineating TB transmission patterns in rural populations could improve TB control. We conducted a prospective population-based study of culture-positive pulmonary TB patients diagnosed between July 1, 2009 and December 31, 2020 in two rural counties in China. Genomic clusters were defined with a threshold distance of 12-single-nucleotide-polymorphisms, based on whole-genome sequencing. Risk factors for clustering were identified by logistic regression. Transmission links were sought through epidemiological investigation of genomic-clustered patients. Of 1517 and 751 culture-positive pulmonary TB patients in Wusheng and Wuchang counties, respectively, 1289 and 699 strains were sequenced. Overall, 624 (31.4%, 624/1988) patients were grouped into 225 genomic clusters. Epidemiological links were confirmed in 41.8% (196/469) of clustered isolates, including family (32.7%, 64/196) and social contacts (67.3%, 132/196). Social contacts were generally with relatives, within the community or in shared aggregated settings outside the community, but the proportion of clustered contacts in each category differed between the two sites. The time interval between diagnosis of student cases and contacts was significantly shorter than family and social contacts, probably due to enhanced student contact screening. Transmission of multidrug-resistant (MDR) strains was likely responsible for 81.4% (83/102) of MDR-TB cases, with minimal acquisition of additional resistance mutations. A large proportion of TB transmission in rural China occurred among social contacts, suggesting that active screening and aggressive contact tracing could benefit TB control, but contact screening should be tailored to local patterns of social interactions.

Improved Registration Algorithm Based on Double Threshold Feature Extraction and Distance Disparity Matrix.

Entire surface point clouds in complex objects cannot be captured in a single direction by using noncontact measurement methods, such as machine vision; therefore, different direction point clouds should be obtained and registered. However, high efficiency and precision are crucial for registration methods when dealing with huge number of point clouds. To solve this problem, an improved registration algorithm based on double threshold feature extraction and distance disparity matrix (DDM) is proposed in this study. Firstly, feature points are extracted with double thresholds using normal vectors and curvature to reduce the number of points. Secondly, a fast point feature histogram is established to describe the feature points and obtain the initial corresponding point pairs. Thirdly, obviously wrong corresponding point pairs are eliminated as much as possible by analysing the Euclidean invariant features of rigid body transformation combined with the DDM algorithm. Finally, the sample consensus initial alignment and the iterative closest point algorithms are used to complete the registration. Experimental results show that the proposed algorithm can quickly process large data point clouds and achieve efficient and precise matching of target objects. It can be used to improve the efficiency and precision of registration in distributed or mobile 3D measurement systems.

Research on the reaction mechanism and modification distance of oil shale during high-temperature water vapor pyrolysis

When oil shale is pyrolyzed with high-temperature water vapor as a heat carrier fluid, the water vapor will participate in the pyrolysis reaction of organic matter, to change the release characteristics of oil and gas products. Based on the self-designed long reaction system of oil shale pyrolysis by injecting water vapor, this paper deeply studies the quantitative law of water vapor temperature and reaction distance on oil upgrading, compares the quality of shale oil using different pyrolysis methods, and reveals the mechanism of upgrading of oil shale pyrolysis by injecting water vapor. The change of heteroatom and light component contents of shale oil can indicate the change in shale oil quality. The relationship between the two indexes and the reaction distance follows the Boltzmann distribution, and the relationship is called the modification distance. When the injection temperature is 450 °C, the modification distance of shale oil is 1400 mm. When the injection temperature reaches 500 °C, the modification distance extends to 2600 mm. Moreover, when the temperature of the water vapor is low, the reaction intensity is low, the upgrading level is low, and the modification distance is short. However, when the temperature of the water vapor is high, the shale oil's rapid hydro-upgrading distance increases, and the upgrading degree is also enhanced. To make oil shale fully pyrolyzed and form shale oil with good quality, the injection temperature should be at least 500 °C. In that case, the reaction distance of 2600 mm is the threshold distance of oil upgrading. The light component content in the shale oil obtained by the pyrolysis of oil shale with water vapor can be two times that obtained by direct distillation and three times that of crude oil.

Accessibility measurements for urban parks considering age-grouped walkers’ sectorial travel behavior and built environment

A walking-accessible urban park system is essential to the physical and mental health of urban residents. However, it is difficult to accurately describe the walking behavior of elderly and young visitors using empirical models (i.e., empirical threshold distance and empirical decay function), because of the differences in walking ability and distance decay among visitors of different ages. To address this challenge, this study used survey data to extract the travel behavior of elderly and younger visitors from a survey of 3625 walking respondents using a sectional threshold distance in central Wuhan. A multiple linear regression model was then built to discover how the factors influence the sectional threshold distance for different age groups. The results show that the travel time threshold for elderly visitors was approximately 0.47–1 min shorter than for other visitors, and the difference became more obvious for the 85th percentile of visitors’ segment travel time. The correlation analysis and regression results suggest that the surrounding built environment, such as restaurants, mostly had to a positive impact on sectional threshold distances, while park facilities were negatively correlated with the threshold distance. This consequently led to different accessibility levels for visitors by age, and elderly people presented an accessibility 0.0012 person/ha lower than young visitors. These findings provide a more accurate and refined decision-making basis for urban planners and managers to optimize park layouts.

Stochastic resetting of a population of random walks with resetting-rate-dependent diffusivity

We consider the problem of diffusion with stochastic resetting in a population of random walks where the diffusion coefficient is not constant, but behaves as a power-law of the average resetting rate of the population. Resetting occurs only beyond a threshold distance from the origin. This problem is motivated by physical realizations like soft matter under shear, where diffusion of a walk is induced by resetting events of other walks. We first reformulate in the broader context of diffusion with stochastic resetting the so-called Hébraud–Lequeux model for plasticity in dense soft matter, in which diffusivity is proportional to the average resetting rate. Depending on parameter values, the response to a weak external field may be either linear, or non-linear with a non-zero average position for a vanishing applied field, and the transition between these two regimes may be interpreted as a continuous phase transition. Extending the model by considering a general power-law relation between diffusivity and average resetting rate, we notably find a discontinuous phase transition between a finite diffusivity and a vanishing diffusivity in the small field limit.

Assessing patients’ acceptable and realised distances to determine accessibility standards for the size of catchment areas in outpatient care

Healthcare planning aims to ensure availability of care in a needs-based, evenly distributed and locally available manner. However, many planning mechanisms lack accessibility standards. To determine standards, catchment areas must be derived from health-related travel assessments and a population's distance acceptance for different medical specialisation levels.We estimated distance acceptance using representative cross-sectional survey data (n = 1.598). Moreover, we used utilization data covering 88% of the German population (2014/15) to calculate realised travel distances for six medical specialties (n = 676.255.605 cases). We specified a gravity-based distance decay function and estimated regression-based distance thresholds from both samples.Realised distances were mostly below 30 min (90% of cases) indicating appropriate mean accessibility. The 5% observed distance threshold was between 23.7 min for GPs and 47.6 min for dermatologists. Depending on medical speciality, distance acceptance was mainly determined by distance, age, activity level and town size for GP visits and by health and income for specialist care. 5% acceptance thresholds varied between 27.9 min to GPs for elderly patients and 51.6 min to orthopaedists for younger patients. Acceptable distances for 90% of the population were 6 (8) minutes to GPs (specialists). The variation of thresholds, which depended on socio-demographic and health variables and the population share that is fully accepting, illustrates that healthcare planners should move beyond averages to realise equal access for equal need.

Delineating Mycobacterium abscessus population structure and transmission employing high-resolution core genome multilocus sequence typing

Mycobacterium abscessus is an emerging multidrug-resistant non-tuberculous mycobacterium that causes a wide spectrum of infections and has caused several local outbreaks worldwide. To facilitate standardized prospective molecular surveillance, we established a novel core genome multilocus sequence typing (cgMLST) scheme. Whole genome sequencing data of 1991 isolates were employed to validate the scheme, re-analyze global population structure and set genetic distance thresholds for cluster detection and taxonomic identification. We confirmed and amended the nomenclature of the main dominant circulating clones and found that these also correlate well with traditional 7-loci MLST. Dominant circulating clones could be linked to a corresponding reference genome with less than 250 alleles while 99% of pairwise comparisons between epidemiologically linked isolates were below 25 alleles and 90% below 10 alleles. These thresholds can be used to guide further epidemiological investigations. Overall, the scheme will help to unravel the apparent global spread of certain clonal complexes and as yet undiscovered transmission routes.

A parsimonious parametrization of the Direct Sampling algorithm for multiple-point statistical simulations

Multiple-point statistics algorithms allow modeling spatial variability from training images. Among these techniques, the Direct Sampling (DS) algorithm has advanced capabilities, such as multivariate simulations, treatment of non-stationarity, multi-resolution capabilities, conditioning by inequality or connectivity data. However, finding the right trade-off between computing time and simulation quality requires tuning three main parameters, which can be complicated since simulation time and quality are affected by these parameters in a complex manner. To facilitate the parameter selection, we propose the Direct Sampling Best Candidate (DSBC) parametrization approach. It consists in setting the distance threshold to 0. The two other parameters are kept (the number of neighbors and the scan fraction) as well as all the advantages of DS. We present three test cases that prove that the DSBC approach allows to identify efficiently parameters leading to comparable or better quality and computational time than the standard DS parametrization. We conclude that the DSBC approach could be used as a default mode when using DS, and that the standard parametrization should only be used when the DSBC approach is not sufficient.

Patterns and correlates of hepatitis C virus phylogenetic clustering among people living with HIV in Australia in the direct-acting antiviral era: A molecular epidemiology study among participants in the CEASE cohort.

Background and AimsIn moving towards the elimination of hepatitis C virus (HCV) infection among people living with HIV, understanding HCV transmission patterns may provide insights to guide and evaluate interventions. In this study, we evaluated patterns of, and factors associated with HCV phylogenetic clustering among people living with HIV/HCV co‐infection in Australia in the direct‐acting antiviral era.MethodsHCV RNA was extracted from dried blood spot (DBS) samples collected between 2014 and 2018 in the CEASE cohort study. The HCV Core‐E2 region was amplified by a polymerase chain reaction and Sanger sequenced. Maximum likelihood phylogenetic trees (1000 bootstrap replicates) were used to identify patterns of clustering (3% genetic distance threshold). Mixed‐effects logistic regression was used to determine correlates of phylogenetic clustering. Factors assessed were sexual risk behavior, education, injecting drug use, housing, employment, HIV viral load, age, sex, and sexuality.ResultsPhylogenetic trees were reconstructed for HCV subtype 1a (n = 139) and 3a (n = 63) sequences, with 29% (58/202) in a pair or cluster. Overall (n = 202), phylogenetic clustering was positively associated with younger age (under 40; adjusted odds ratio [aOR] 2.52, 95% confidence interval [CI] 1.20–5.29), and among gay and bisexual men (n = 168), was positively associated with younger age (aOR 2.61, 95% CI 1.10–6.19), higher education (aOR 2.58, 95% CI 1.09–6.13), and reporting high‐risk sexual behavior (aOR 3.94, 95% CI 1.31–11.84). During follow‐up, five reinfections were observed, but none were in phylogenetic clusters.ConclusionThis study found a high proportion of phylogenetic relatedness, predominantly among younger people and gay and bisexual men reporting high‐risk sexual behavior. Despite this, few reinfections were observed, and reinfections demonstrated little relationship with known clusters. These findings highlight the importance of rapid HCV treatment initiation, together with monitoring of the phylogeny.

A new method for indexing continuous IoT data flows in metric space

The continuous production of heterogeneous internet of things (IoT) data created a new challenge, which is their storage and retrieve efficiently. In this work, a new method of indexing, called threshold distance (TD), is proposed in the fog‐cloud architecture. In this method, the fog layer is divided into two levels: a clustering level and an indexing level. In the clustering fog level, the first data flow is grouped into clusters of homogenous objects using the density‐based spatial clustering applications with noise (DBSCAN) algorithm. In the indexing fog level, objects in each cluster are indexed in separated generalized hyperplane‐trees (GHT). After the clustering of the next data flow, objects are inserted in existing GHT or new GHT are created according the comparison of the distances between centers of the next clusters and those of the first clusters (took as representatives of their corresponding indexes) with a threshold distance value. To test the efficiency of the TD method, the experimental results were compared with those of our second proposed method called creation of a new tree (CNT) in which, data of each cluster is indexed in a new GHT. The experimental results show that the efficiency of the TD method in GHT construction depend on the size of the data flow. For the parallel kNN search, the TD method proved its efficiency whatever the size of the data flow.

Real-Time Recognition of Loading Cycles’ Process Based on Electric Mining Shovel Monitoring

An automatic recognition algorithm based on the feature extraction of working parameters to recognize each state in the loading cycle process of an electric mining shovel was proposed. The working parameters were collected using the electric shovel’s online monitoring system. The swing angle of the shovel boom and motor operating signals were used as key recognition objects; the waveform features of each stage were extracted as recognition marks in the loading cycle of an electric shovel using the time domain characteristic analysis method. The algorithm was developed to recognize the loading cycles in real time. Moreover, the dynamic time warping (DTW) algorithm was used to detect and classify the preliminary recognition results by optimizing its distance threshold parameters, reducing the error rate of the model. The method was validated by comparing synchronous video-recordings with the results of the algorithm. Results showed that the proposed recognition method of the shovel loading cycle process exhibited real-time performance and high accuracy in understanding the different work tasks, providing effective data support for mining and the analysis of shovel working parameters, helping to improve the energy efficiency of electric mining shovel.

Statistical and Comparative Analysis of Multi-Channel Infrared Anomalies before Earthquakes in China and the Surrounding Area

Abundant infrared remote sensing images and advanced information processing technologies are used to predict earthquakes. However, most studies only use single long-wave infrared data or its products, and the accuracy of prediction is not high enough. To solve this problem, this paper proposes a statistical method based on connected domain recognition to analyze multi-channel anomalies. We extract pre-seismic anomalies from multi-channel infrared remote sensing images using the relative power spectrum, then calculate positive predictive values, true positive rates and probability gains in different channels. The results show that the probability gain of the single-channel prediction method is extremely low. The positive predictive value of four-channel anomalies is 41.94%, which is higher than that of single-channel anomalies with the same distance threshold of 200 km. The probability gain of the multi-channel method is 2.38, while that of the single-channel method using the data of any channel is no more than 1.26. This study shows the advantages of the multi-channel method to predict earthquakes and indicates that it is feasible to use multi-channel infrared remote sensing images to improve the accuracy of earthquake prediction.

A novel image-based approach for interactive characterization of rock fracture spacing in a tunnel face

This paper presents a novel integrated method for interactive characterization of fracture spacing in rock tunnel sections. The main procedure includes four steps: (1) Automatic extraction of fracture traces, (2) digitization of trace maps, (3) disconnection and grouping of traces, and (4) interactive measurement of fracture set spacing, total spacing, and surface rock quality designation (S-RQD) value. To evaluate the performance of the proposed method, sample images were obtained by employing a photogrammetry-based scheme in tunnel faces. Experiments were then conducted to determine the optimal parameter values (i.e. distance threshold, angle threshold, and number of fracture trace grouping) for characterizing rock fracture spacing. By applying the identified optimal parameters involved in the model, the proposed method could lead to excellent qualitative results to a new tunnel face. To perform a quantitative analysis, three methods (i.e. field, straightening, and the proposed method) were employed in the same study and comparisons were made. The proposed method agrees well with the field measurement in terms of the maximum and average values of measured spacing distribution. Overall, the proposed method has reasonably good accuracy and interactive advantage for estimating the ultimate fracture spacing and S-RQD. It can be a possible extension of existing methods for fracture spacing characterization for two-dimensional (2D) rock tunnel faces.

An inverted ‘U-shaped’ pattern: the residence distance of adult children and the mental health of elderly in rural China

ABSTRACT Using data from three waves of the China Health and Retirement Longitudinal Study, this study identifies a causal effect of the distance adult children reside from their parents on the mental health of the rural elderly. We use panel correlated random effect methods with instrumental variables to address potential confounding effects of reverse causality and unobserved omitted variables. We find that the impact of the distance adult children live from their parents on parental mental health exhibits an inverted ‘U-shaped’ pattern that first increases (good) and then slowly decreases (poor). 80 kilometers is a threshold of residence distance for the mental health of the rural elderly. Further analysis finds that the effect of the residence distance on the mental health of rural elderly has statistically significant differences by gender of the elderly.