Average Nearest-neighbor Distance Research Articles

Quantitative Analysis of Spatial Distribution Characteristics of Traditional Villages in Hunan Province

This study takes 658 traditional villages in Hunan province as the research object. Relying on ArcGIS geographic information system, the traditional villages in Hunan province were abstracted into point sets with attribute information. By means of average nearest neighbor distance analysis, kernel density analysis and intercity distribution comparison, the basic geographical characteristics of traditional villages in Hunan province were summarized, that is, significant agglomeration distribution, three agglomeration areas and uneven intercity distribution. Multiple types of natural geographical factors were superimposed, such as elevation, slope aspect, slope, river, water systems, annual precipitation and annual average temperature, so as to analyze the impact of elevation topography, river system and climate conditions on village site selection. With the help of geographic detector tool, the correlation between elevation, slope, water system, annual average temperature, annual precipitation and village distribution was quantitatively analyzed. Through the analysis of correlation degree, interaction and single factor characteristics, it is concluded that natural geographical factors are related to village distribution and multiple factors interact with each other. Based on the quantitative analysis of interactions between traditional villages and the natural environment, the distribution characteristics of traditional villages have been summarized, providing reference for the subsequent systematic research and protection of traditional villages.

The spatial distribution of retail outlets in Urumqi: The application of points of interest

Abstract Studies on the distribution of retail outlets are crucial for optimizing urban resource allocation, and their rationalized layout plays an important role in developing urban economies and meeting consumer demand. However, the literature on the subject has been limited by data collection. In the era of big data, there has been an emergence of geo-referenced data that are more accurate and convenient and thus more able to be applied in the retail analysis. This study addresses this lacuna by exploring the spatial distribution of various retail outlets with the application of points of interest. Our study demonstrates that (1) the retail outlets in Urumqi are concentrated in the inner city. The inner-city area has a higher density distribution of retail outlets, and the development of the retail function is more mature. (2) Various categories of retail outlets display dissimilar agglomeration characteristics and hot spots. Specialty stores, clothing and footwear stores, convenience stores, and home-building material markets have lower average nearest-neighbor distances. (3) The retail outlets in the subject area are directionally distributed in the northwest–southeast direction, which is the result of both the topographical condition and government intervention in Urumqi. (4) Various categories of retail outlets tend to agglomerate at different scales. These results are conducive to the exploration of the location rules and layout preferences of retail locations, and they provide a reference for guiding the adjustment and optimization of retail layouts.

Spatial-Temporal Analysis of the Forest Fragments Surrounding a Conservation Unit in the Southern Region of Brazil

In recent years, anthropogenic actions have intensified forest fragmentation, causing several damages to the landscape’s natural components, propagating the loss of biodiversity. This study aims to present an analysis of the forest fragments in a conservation unit located at southern of Brazil. The evaluation was carried out for the years 1998, 2008, and 2018, by using landscape metrics and classification of remote sensing imagery of the Landsat satellite. The following metrics were analyzed: area and edge, shape, core area, and aggregation. The results indicated an increase of 16.88% in the total area of vegetation, and the percentage of fragments increased from 16.16% to 18.89%. The number of fragments decreased, resulting in an increase of the mean area in 5.4 ha. The percentage of vegetation under border effect changed from 40.2% to 37.1%. In 1998, the average nearest neighbor distance was 155.4 m, and in 2018, 149.7 m. However, this distance is still classified as a high degree of isolation, which hinders the movement of organisms and the dispersion of species. Thus, all the analyzed metrics indicated a decrease in the fragmentation, except for the edge density metric, in which its increase of 1.86 pointed to a lower degree of conservation during the analyzed period. A study of this nature is important as it provides subsidies for future researches and can contribute to action strategies to be adopted in the management plan of the area.

Controlling the Interparticular Distances of Extended Non-Close-Packed Colloidal Monolayers.

A versatile method for the preparation extended, well-ordered, non-close-packed monolayers of silica nanoparticles (137 ± 4 nm diameter) with adjustable interparticle distances is presented, which is based on a simple self-assembly procedure using aqueous dispersion with different ionic strengths. It is shown that these structures can be successfully transferred to air without suffering from aggregation. Scanning electron microscopy (SEM) is used to characterize the structures after transfer into the atmosphere. These investigations were combined with a quartz crystal microbalance with dissipation (QCM-D) experiments to follow the self-assembly process in solution. The nearest-neighbor distance distribution reveals a monotonous decrease of the average nearest-neighbor distance from 290 to 200 nm with increasing ionic strength from 0.05 to 1 mM, which indicates an increased shielding of the electrostatic interaction with increasing ionic strength. The observed saturation coverages for all studied ionic strengths are well explained with an effective hard-sphere model in which the saturation coverage is limited by Coulomb repulsion. However, at ionic strengths above 1 mM, significant amounts of aggregates are found in the dried samples, suggesting that the observed aggregates at high ionic strengths are formed during the drying process caused by capillary forces between the particles. Tuning the barrier for lateral diffusion, e.g., by changing the surface morphology or functionalization of the particles will offer a route to further extend the range of particle distances. The present approach can be easily expanded to a broad range of colloidal materials on surfaces, while it only requires low-cost laboratory equipment.

Spatial modeling of the spread of scabies and environmental sanitation as a risk factor among schoolchildren: a case-control study

BACKGROUND Scabies is a World Health Organization neglected tropical disease common in children in low-and middle-income countries. The prevalence of scabies, especially in tropical countries, is still quite high at more than 200 million cases per year. Transmission of scabies is predominantly via skin-to-skin contact. The purpose of the study was to determine the epidemiology of clinical scabies among schoolchildren and spatial modeling using geographic information systems (GIS).METHODSA study of unmatched case-control design with a ratio of 1: 1 was performed to identify specific risk factors of scabies. Cases were patients with clinical scabies and controls were healthy people in the area. A total of 100 students were involved in the study. Simple and multiple logistic regression was used to test any association between the variables. Geographical Information Systems (GIS) modeling was used to determine the spatial distribution of clinical scabies based on 69 cases.RESULTThere was a significant association between the level of environmental sanitation and the prevalence of clinical scabies (OR = 2.53;95% C.I. 1.11-5.74). Multivariate analysis showed that the level of environmental sanitation was significant (AOR = 3.05;95% C.I. 1.19-7.81). Risk factors for developing clinical scabies increased to 3 times after considering other risk factors, namely gender, age group and respondent education level. Analysis of average nearest neighbor distance showed that the spatial distribution of clinical scabies was clustered. CONCLUSIONSThe distribution of clinical scabies was spatial clustering, and prediction of transmission in a clockwise direction with Southeast and Northwest ellipses.

Spatial patterns of snake diversity in an urban area of north-east Brazil

The distribution of animal populations within an assemblage includes a wide variety of patterns, which are fundamental to understanding population dynamics and aid in conservation actions. We examined a snake assemblage in an urban area to describe species distribution patterns and to identify which places are more likely to contain snakes, both venomous and non-venomous. The study was conducted in the urban area of the municipality of Rio Tinto in north-east Brazil. We used a geostatistical modelling technique called ordinary kriging to identify which places were more likely to contain snakes, and a statistical spatial method (average nearest neighbour distance) to detect distribution patterns of snake species within the study area. A total of 291 individuals distributed among 28 species were recorded. The snakes were found in streets, homes, churches, university campus, streams, and even in local supermarkets. Ordinary kriging showed that the area of distribution of individuals was concentrated at three distinct points located in the centre of the urban area. The significant results of the average nearest neighbour distance analysis showed a clustered distribution for two species and dispersed distributions for eight species. Information on urban sites where snakes are more likely to be found is important not only for conservation, but also to help local citizens better understand and live amongst snakes

A Spatiotemporal Analysis of Heroin-Related Calls for Emergency Medical Services and Community-Health Centers in Boston, Massachusetts

Using a combination of data derived from the U.S. Census Bureau, the Substance Abuse and Mental Health Service Administration’s Behavioral Health Systems Locator and the Boston Police Department’s Incident Reports, this study examines the spatio-temporal distribution of calls for medical assistance following a heroin-related injury between 2015 and 2018. As well, an examination is conducted regarding the accessibility of Health Care Centers (HCCs) in relation to individuals in need of medical assistance. Distance-based measures of spatial association, including nearest neighbor and K-function analysis, were used to determine the clustering of calls at various spatial scales. Structural neighborhood characteristics (i.e., distance to the closest HCC) and physical and social vulnerability were used to predict the rate of calls for a heroin-related injury per 1,000 persons in the city of Boston using a spatial autoregressive model. HCC catchment areas for the set of medical emergency calls were created using Voronoi tessellations. Results showed that the average nearest neighbor distance (NND) of each call for medical assistance was approximately 187 m or .12 miles. Calls for assistance became more probable and increasingly more spatially concentrated over the study period. The K-function analysis revealed that the calls clustered at different spatial scales and in proximity to HCCs. Average distance to the nearest HCC and Household/Disability vulnerability were significantly associated with the census tract call rate per 1,000 persons. The average travel distance between the calls for medical assistance and the nearest HCC was 941 m, or just over a half-mile. Policy implications for the provision, through HCCs, of a focused and comprehensive community-based support system in a large urban city for individuals with serious drug problems are discussed in context.

Spatiotemporal Variation and Hot Spot Detection of Visceral Leishmaniasis Disease in Kashi Prefecture, China.

Visceral leishmaniasis (VL) remains a serious public health problem in China. To explore the temporal, spatial, and spatiotemporal characteristics of visceral leishmaniasis (VL), the spatial and spatiotemporal clustering distribution and their relationships with the surrounding geographic environmental factors were analyzed. In this study, the average nearest-neighbor distance (ANN), Ripley’s K-function and Moran’s I statistics were used to evaluate spatial autocorrelation in the VL distribution of the existing case patterns. Getis–Ord Gi* was used to identify the hot-spot and cold-spot areas based on Geographic Information System (GIS), and spatiotemporal retrospective permutation scan statistics was used to detect the spatiotemporal clusters. The results indicated that VL continues to be a serious public health problem in Kashi Prefecture, China, particularly in the north-central region of Jiashi County, which is a relatively high-risk area in which hot spots are distributed. Autumn and winter months were the outbreak season for VL cases. The detection of spatial and spatiotemporal patterns can provide epidemiologists and local governments with significant information for prevention measures and control strategies.

A regularity index for dendrites - local statistics of a neuron's input space.

Neurons collect their inputs from other neurons by sending out arborized dendritic structures. However, the relationship between the shape of dendrites and the precise organization of synaptic inputs in the neural tissue remains unclear. Inputs could be distributed in tight clusters, entirely randomly or else in a regular grid-like manner. Here, we analyze dendritic branching structures using a regularity index R, based on average nearest neighbor distances between branch and termination points, characterizing their spatial distribution. We find that the distributions of these points depend strongly on cell types, indicating possible fundamental differences in synaptic input organization. Moreover, R is independent of cell size and we find that it is only weakly correlated with other branching statistics, suggesting that it might reflect features of dendritic morphology that are not captured by commonly studied branching statistics. We then use morphological models based on optimal wiring principles to study the relation between input distributions and dendritic branching structures. Using our models, we find that branch point distributions correlate more closely with the input distributions while termination points in dendrites are generally spread out more randomly with a close to uniform distribution. We validate these model predictions with connectome data. Finally, we find that in spatial input distributions with increasing regularity, characteristic scaling relationships between branching features are altered significantly. In summary, we conclude that local statistics of input distributions and dendrite morphology depend on each other leading to potentially cell type specific branching features.

Arrays of high aspect ratio magnetic microstructures for large trapping throughput in lab-on-chip systems

Here we report a novel technology to obtain arrays of highly efficient magnetic micro-traps that relies on simple fabrication process. Developed micro-traps consist in chains of iron particles diluted in polydimethylsiloxane (PDMS). We analyzed the microstructure of the composite membrane by X-ray tomography. It revealed the predominance of aligned chain-like agglomerates. Largest traps, with diameter ranging from 4 to 11 µm, are found to be the most efficient. The trap arrays were characterized by a density of 1300 magnetic micro-traps/mm2, an average nearest neighbor distance of 21 µm. Implemented in a microfluidic channel operating at a relatively high flow rate of 0.97 µL/s—a flow velocity of 8.3 mm/s—we measured a trapping efficiency of more than 99.7%, with a throughput of up to 7100 trapped beads/min. These performances are competitive with other approaches like hydrodynamic trapping. The strengths of this technology are its simple fabrication and easy handling.

Local and global recurrences in dynamic gas-solid flows

We investigate recurrent patterns in a lab-scale fluidized bed consisting of Np ≈ 57 000 glass particles by the means of computational fluid dynamics and the discrete element method (CFD-DEM). We generalize single-point measures for recurrence quantification analysis (RQA) to spatially extended particle density fields and compare the embedding dimensions necessary to unambiguously identify similar states. In accordance with many previous studies, we find locally very low-dimensional behavior (Dloc ≈ 5). Globally, the correlation dimension, i.e. the number of effective degrees of freedom, increases to Dglobal ≈ 18, which is still several orders of magnitude smaller than the 6Np microscopic translational degrees of freedom and explains the observed, characteristic structures. Distance plots reveal a combination of fast, recurrent motion interrupted by rare events like large eruptions. The temporal evolution of the average nearest-neighbor distance shows a rapid initial drop and follows a power law related to the correlation dimension for longer times. Given a sufficient tolerance, most states reappear after a few seconds, which indicates why in recent, small-scale recurrence CFD (rCFD) simulations, the complicated long-term bed motion could be approximated with information from short-term studies within the scope of current computation techniques. From the perspective of numerical efficiency, the presented analysis allows to determine the shortest time series from which a significant amount of information on the underlying system may be obtained.

Magnetoencephalographic Spike Analysis in Patients With Focal Cortical Dysplasia: What Defines a “Dipole Cluster”?

BackgroundThe purpose of this study is to clarify the source distribution patterns of magnetoencephalographic spikes correlated with postsurgical seizure-free outcome in pediatric patients with focal cortical dysplasia. Patients and methodsThirty-two patients with pathologically confirmed focal cortical dysplasia were divided into seizure-free and seizure-persistent groups according to their surgical outcomes based on Engel classification. In each patient, presurgical magnetoencephalography was reviewed. Dipole sources of magnetoencephalographic spikes were calculated according to a single dipole model. We obtained the following quantitative indices for evaluating dipole distribution: maximum distance over all pairs of dipoles, standard deviation of the distances between each dipole and the mean coordinate of all dipoles, average nearest neighbor distance, the rate of dipoles located within 10, 20, and 30 mm from the mean coordinate, and the rate of dipoles included in the resection. These indices were compared between the two patient groups. ResultsAverage nearest neighbor distance was significantly smaller in the seizure-free group than in the seizure-persistent group (P = 0.008). The rates of dipoles located within 10, 20, and 30 mm from the mean coordinate were significantly higher in the seizure-free group (P = 0.001, 0.001, 0.005, respectively). The maximum distance, standard deviation, and resection rate of dipoles did not show a significant difference between the two groups. ConclusionsA spatially restricted dipole distribution of magnetoencephalographic spikes is correlated with postsurgical seizure-free outcomes in patients with focal cortical dysplasia. The distribution can be assessed by quantitative indices that are clinically useful in the presurgical evaluation of these patients.

Commonality in the microarchitecture of trabecular bone: A preliminary study.

Understanding the relationship between the microstructure and mechanical function of trabecular bone is critical for prediction and prevention of bone fragility fractures. However, a detailed understanding of the structural design of trabecular microarchitecture is still missing. This study hypothesized that there exists a commonality in the underlying probabilistic distributions of microstructural features of trabecular bones, whereas the microstructural differences among individuals are primarily describe by a set of scalar parameters. To test the hypothesis, twenty-three trabecular bone specimens were obtained from two anatomic locations (i.e., femoral neck and vertebral body) and a diverse group of seventeen donors of different age and sex. The number, size, spatial location, and orientation of individual plates and rods in the trabecular bone specimens were determined via volumetric decomposition of 3D μCT images using the Individual Trabecula Segmentation (ITS) technique. Then, m/n bootstrap Kolmogorov-Smirnov tests were performed to compare the normalized distributions of size, orientation, and spatial arrangement of trabecular plates and rods in the specimens. The results showed that 100% of the twenty-three normalized distributions of each microstructural feature were statistically equivalent irrespective of individual differences among the bone specimens, except the distributions of rod spatial arrangement (<100%). On the other hand, nonparametric Mann-Whitney U tests showed that a set of scalar parameters (i.e., the number, average size, and average nearest neighbor distance of trabecular plates and rods) were statistically different among the individual specimens (p<0.05). Due to the commonality of the underlying distributions, the individual differences in the trabecular microstructure among the specimens seemed to be reflected primarily by changes in the scalar parameters. The above results strongly support the hypothesis of this study and may shed more light on understanding the natural design of trabecular bone microstructures.

Deposit density of tungsten polymetallic deposits in the eastern Nanling metallogenic belt, China

Estimation of the number of undiscovered mineral deposits is critical for quantitatively assessing mineral resources. Traditional statistic methods are limited to analyzing the spatial distribution of mineral deposits which can be considered spatial point processes because of complexity, self-organized criticality and singularity properties. In this study, spatial statistic methods, including average nearest neighbor distance, Fry analysis, K function and fractal analysis, are used to quantify the agglomeration and fractal characteristics of tungsten polymetallic deposits in the eastern Nanling metallogenic belt (ENMB). Local singularity analysis for W-Sn-Mo-Bi-Be association is used to delineate the permissive areas for tungsten deposits. The results show that tungsten polymetallic deposits are distributed with fractal clustering in region while at random in permissive areas. The summary function comparison shows that the K function analysis based on a heterogeneous process may be more robust than on a homogeneous K function when quantifying the distribution of mineral deposits, especially for endogenic deposits. Furthermore, the concept of mineral equivalent is introduced in this study and the combination of mineral equivalent and radial density model for mineral deposits mitigates the problem of ignoring the proportion of large-, medium-, and small-sized deposits in the uniform deposit density model. The estimation results indicate that there are still good future prospects in this region. This research not only extends the application of spatial statistics in quantifying the spatial distribution of mineral deposits, but also provides a new approach to estimate the number of undiscovered mineral deposits.

Structural Optimization of (Aum‐Agn‐Pdo‐Ptp) (m=10 and n+o+p=10) Tetrametallic Clusters Using a Combined Empirical Potential‐Density Functional (EP‐DF) Approach

AbstractThe putative global minimum structures of (Aum‐Agn‐Pdo‐Ptp) (m=10 and n+o+p=10) tetrametallic clusters with 20 atoms are obtained by basin hopping algorithm using Gupta potential parameters. A system‐comparison approach through combined empirical potential (EP)‐density functional (DF) method is adopted to investigate the energy competition and segregation effect for thirty six structural motifs. Vibrational analysis has been carried out to check the stability of these doped metal clusters. The thermal and chemical stability are measured by binding energy and HOMO‐LUMO gap. We have calculated the excess mixing energy, mixing energy and mixing coefficient, order parameter, average nearest neighbor distance (ANND) and shape deformation parameter for these doped metal clusters. Mixing/segregation effect is also discussed. Overall the calculated energy by EP parameters is lower for moderate number of (Pt, Pd) or higher number of Pt atoms and reasonably accurate for the other doped clusters. Results show that Au and Ag atoms occupy the surface sites while Pt and Pd atoms prefer mostly to the inner and middle shell.

Asymptotics for Euclidean functionals of mixing processes

ABSTRACTWe extend previously known asymptotic results in the framework of subadditive Euclidean functionals and the related superadditive functionals. Our results generalize the standard independent identically distributed assumption, vastly expanding the scope of the existing theory. As an application of our results, a limit theorem for the average nearest neighbor distance is established, extending earlier results in the literature.

Multispectral filter array design without training images

Multispectral images (MSIs) have been studied for many applications; however, limitations persist in techniques to capture them due to the complexity of assembling one or more prisms and multiple sensor arrays in order to detect signals. Inspired by the application of color filter arrays to commercial digital RGB cameras, a number of researchers have studied multispectral filter arrays (MSFAs) to solve this problem. Determining the measurement wavelength and pattern of an MSFA is important for improving the quality of the demosaicked image. Some conventional studies for designing MSFAs have used training data and have optimized the measurement wavelengths and the pattern by iteratively minimizing the error between the training data and the demosaicked images. We propose a metric to evaluate an MSFA without MSIs, and optimize the measurement wavelengths and the pattern of the MSFA by minimizing the metric. The proposed metric measures the sampling distance between filters in a spatial–spectral domain and quantifies the dispersion of the sampling points by average nearest-neighbor distance (ANND) under a given arbitrary MSFA. Since the quality of the demosaicked image is assumed to be proportional to the degree of dispersion of the sampling points in the spatial–spectral domain, we optimize the MSFA by minimizing the ANND in a nested simulated annealing process. Experimental results show that the optimized MSFA obtained using our method attained a higher peak signal-to-noise ratio (PSNR) than conventional untrained MSFAs in many cases. In addition, the performance difference between some trained MSFAs and the proposed MSFA was small. We also confirmed the validity of the proposed ANND by a comparison with the mean square error obtained from MSI datasets.

Computational modeling sheds light on structural evolution in metallic glasses and supercooled liquids

This article presents an overview of three challenging issues that are currently being debated in the community researching on the evolution of amorphous structures in metallic glasses and their parent supercooled liquids. Our emphasis is on the valuable insights acquired in recent computational analyses that have supplemented experimental investigations. The first idea is to use the local structural order developed, and in particular its evolution during undercooling, as a signature indicator to rationalize the experimentally observed temperature-dependence of viscosity, hence suggesting a possible structural origin of liquid fragility. The second issue concerns with the claim that the average nearest-neighbor distance in metallic melts contracts rather than expands upon heating, concurrent with a reduced coordination number. This postulate is, however, based on the shift of the first peak maximum in the pair distribution function and an average bond length determined from nearest neighbors designated using a distance cutoff. These can instead be a result of increasing skewness of the broad first peak, upon thermally exacerbated asymmetric distribution of neighboring atoms activated to shorter and longer distances under the anharmonic interatomic interaction potential. The third topic deals with crystal-like peak positions in the pair distribution function of metallic glasses. These peak locations can be explained using various connection schemes of coordination polyhedra, and found to be present already in high-temperature liquids without hidden crystal order. We also present an outlook to invite more in-depth computational research to fully settle these issues in future, and to establish more robust structure-property relations in amorphous alloys.

Detection of airbag impact-induced cone photoreceptor damage by adaptive optics scanning laser ophthalmoscopy: a case report

BackgroundThe purpose of this study was to report a case of traumatic maculopathy with para-central visual field defects following an impact by airbag deployment using adaptive optics scanning laser ophthalmoscopy (AO-SLO).Case presentationA 51-year-old man was involved in a motor vehicular accident and his left eye was struck by the deployed airbag, resulting in a para-central scotoma. The patient underwent a full ophthalmologic examination, spectral-domain optical coherence tomography (SD-OCT), and imaging with prototype AO-SLO systems (Canon Inc.) at 14 and 22 months after the injury. Images focused on the photoreceptor layer were recorded in the foveal area, and a montage of AO-SLO images was created. On AO-SLO, focal dark areas could be observed in the left eye at 14 months after the injury. The analysis showed that the cone mosaic (cone density, 16503/mm2; ratio of hexagonal Voronoi domain, 36.3 %; average nearest-neighbor distance (NND)/expected NND, 0.606) was disordered compared with the normal area of the same eye (cone density, 24821/mm2; ratio of hexagonal Voronoi domain, 44.1 %; average NND/expected NND, 0.739). The cone defect area corresponded to the area of the scotoma. A second AO-SLO was performed on the patient at 22 months after the injury and although there were still areas with reduced cone reflectivity, partial improvement of cone mosaic was detected by AO-SLO at this time point.ConclusionPartial recovery of damaged cone photoreceptors following closed globe blunt ocular trauma can be documented using AO-SLO longitudinal tracking.

Recovery of American peregrine falcons along the upper Yukon River, Alaska

ABSTRACTAmerican peregrine falcons (Falco peregrinus anatum) throughout North America declined following the introduction of dichlorodiphenyltrichloroethane (DDT) in 1947. In the 1960s, intensive studies were initiated in many areas of North America, including interior Alaska, to determine the cause of the decline and assess population status. From 1977 to 2015, we studied peregrine falcons along a 265‐km section of the upper Yukon River in east‐central Alaska. We counted occupied territories, documented breeding success and productivity, and collected unhatched eggs for contaminant analysis. We observed 1,602 occupied territories and 2,349 nestlings. Annual breeding success averaged 64%, and annual productivity averaged 1.54 nestlings/territory and 2.38 nestlings/successful territory. Annual rates of increase in the number of occupied territories were greatest in the late 1970s and 1980s (8.6%), moderate in the 1990s (2.8%), and least in the 2000s (1.5%). Reproductive metrics were highest in the late 1970s and 1980s, declining in recent years. As the number of occupied territories increased (14–60) and average nearest neighbor distance decreased (from 9.8 km to 2.6 km), breeding success declined (from 71% in the 1980s to 57% in the 2000s). Productivity, as measured by nestlings per occupied territory, declined (from 1.84 in the 1980s to 1.29 in the 2000s). Nestlings per successful territory also declined from 2.56 in the 1980s to 2.25 in the 2000s. Survey data for 1966–2015 reveal a declining population in the 1960s and early 1970s, increasing in the late 1970s through the early 2000s, and apparently stabilizing in recent years. The recovery of this local population took roughly 40 years, from a low of 12 occupied territories in early 1970s to 60 in 2012–2014. Importantly, the recovery of American peregrine falcons in Alaska occurred without captive breeding, releases, or nest site manipulations. Long‐term studies are essential in fully understanding the biology of any species, and this study provides insight into the unaided, natural recovery of American peregrine falcons in Alaska. © 2016 The Wildlife Society.