Non-random Spatial Distribution Research Articles

Landscape level associations between birds, mosquitoes and microclimates: possible consequences for disease transmission?

BackgroundMosquito-borne diseases are on the rise. While climatic factors have been linked to disease occurrences, they do not explain the non-random spatial distribution in disease outbreaks. Landscape-related factors, such as vegetation structure, likely play a crucial but hitherto unquantified role.MethodsWe explored how three critically important factors that are associated with mosquito-borne disease outbreaks: microclimate, mosquito abundance and bird communities, vary at the landscape scale. We compared the co-occurrence of these three factors in two contrasting habitat types (forest versus grassland) across five rural locations in the central part of the Netherlands between June and September 2021.ResultsOur results show that forest patches provide a more sheltered microclimate, and a higher overall abundance of birds. When accounting for differences in landscape characteristics, we also observed that the number of mosquitoes was higher in isolated forest patches.ConclusionsOur findings indicate that, at the landscape scale, variation in tree cover coincides with suitable microclimate and high Culex pipiens and bird abundance. Overall, these factors can help understand the non-random spatial distribution of mosquito-borne disease outbreaks.Graphical

Abstract 6970: identification of spatially enriched cancer cell- and immune cell-regulatory multi-marker-defined prognostic cancer associated fibroblast subsets of human colon cancer

Abstract Introduction: Subsets of cancer-associated fibroblasts (CAFs) in colorectal cancer remain poorly characterized preventing their use as biomarkers and drug targets. Results: Integrated scRNA seq profiling and multiplex staining identified four human CAF subsets These were A1 (PDGFRA+/FAP-/TF), PDGFRAhighA2 (PDGFRA+/FAP+/TF-), PDGFRAlowA2 (PDGFRA-/FAP+/TF-) and A3 (PDGFRA+/FAP-/TF+) (TF: Tissue Factor).Spatial analyses identified spatial associations indicative of specific functional interactions of fibroblast subsets with cancer cells or immune cells. Explorative analyses in six CRC cases suggested, in general, favorable effects of FAP-negative subsets (A1 and A3) on immune features and cancer cell proliferation, whereas FAP-positive subsets PDGFRAhighA2 and PDGFRAlowA2 overall showed pro-tumoral associations. To extend findings, niches were quantitated in U-CAN cohort of approximately 200 stage I-IV cases with around 80% stage II/III. Spatial screening generated more than 1600 different multi-marker-defined tissue metrics. Analyses identified a higher average of A1 density in areas surrounding proliferating vs non-proliferating T-cells, and a higher average PDGFRAlowA2 peri-T-cell density in the low proliferating T-cell group. Regarding cancer cell proliferation, high proliferating cancer islands showed lower peri-epithelial density of A3 and PDGFRAlowA2 cells as compared to low proliferating cancer islands. As for T-cell cancer island infiltration, high peri-cancer island density of A1 and PDGFRAhighA2 was associated with high T-cell cancer island infiltration. Additional analyses related CAF metrics to stage and survival. Density of PDGFRAlow A2 cells increased with stage (I-III), whereas density of A1 showed an opposite pattern with an inverse association with stage (I-III). Regarding survival associations, these were in general stronger for metrics collected in peripheral regions of tumors. Among prognosis signals related to niches referred to above, it was noted that A1 density in peri-cancer regions was significantly associated with good prognosis. Interestingly, this association was not detected when A1 density was scored in total stroma. Among all metrics, the strongest metrics were A1 density in 20μm A1 expansion areas (good prognosis) and T-reg density in the 10μm A3 expansion areas (bad prognosis) (P<0.001; univariate Cox-regression); both in peripheral regions. Conclusion: Four novel CRC CAF subsets, defined by PDGFRalpha, FAP and TF, was identified by integrated single cell RNA seq analyses and multiplex staining with associated digital image analyses. Non-random spatial distribution of these subsets and compartment-specific prognosis associations are compatible with distinct and different functions of these subsets. Citation Format: Linglong Huang, Mercedes Herrera, Jonas Sjölund, Vladimir Chocoloff, Simon Joost, Rasul M. Tabiev, Lina Wik Leiss, Carina Strell, Luis Nunes, Artur Mezheyeuski, David Edler, Anna Martling, Fredrik Pontén, Bengt Glimelius, Tobias Sjöblom, Maria Kasper, Kristian Pietras, Arne Östman. identification of spatially enriched cancer cell- and immune cell-regulatory multi-marker-defined prognostic cancer associated fibroblast subsets of human colon cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6970.

Geospatial analysis of the hospitalisation rate of patients with rheumatoid arthritis in Hunan: a cross-sectional Chinese study

ObjectiveLittle is known about spatial variability of hospitalisation rate (HR) of patients with rheumatoid arthritis (RA) worldwide, especially in China.MethodsA cross-sectional study was conducted among patients with RA admitted to...

Non-response bias in the analysis of the association between mental health and the urban environment: a cross-sectional study in Brussels, Belgium

BackgroundThis paper aims at analysing the impact of partial non-response in the association between urban environment and mental health in Brussels. The potential threats of the partial non-response are biases in survey estimates and statistics. The effect of non-response on statistical associations is often overlooked and evidence in the research literature is lacking.MethodsData from the Belgian Health Interview Survey 2008 and 2013 were used. The association between non-response and potential determinants was explored through logistic regressions.ResultsParticipants with low income, low educational levels, lower or higher age or in households with children were less likely to respond. When adjusting for socio-economic variables, non-response was higher in areas which are less vegetated, more polluted or more urbanised. Because the determinants of non-response and depressive disorders were similar, it is reasonable to assume that there will be more people with mental health problems among the non-respondents. And because more non-responses were found in low vegetation areas, the protective association between green spaces and mental health may be underestimated.ConclusionOur capacity to measure the association between the urban environment and health is affected by non-response in surveys. The non-random spatial and socio-economic distribution of this bias affects the research findings.

Do habitat fragmentation and degradation influence the strength of fine-scale spatial genetic structure in plants? A global meta-analysis.

As primarily sessile organisms, plants often show a non-random spatial distribution of genotypes over distance. This process known as fine-scale spatial genetic structure (FSGS) has been suggested through systematic reviews to depend on life form, mating system, and pollen and seed dispersal vectors, while there is no consensus on its behaviour due to external factors, such as anthropogenic habitat changes. By conducting a systematic review and global meta-analysis of empirical FSGS studies, we aimed to evaluate how anthropogenic habitat fragmentation and degradation influence the strength of FSGS in plant populations by means of the Sp statistic. Moreover, we tested how pollination and seed dispersal vectors contribute to the variation of the Sp statistic. We retrieved 243 FSGS studies from 1960 to 2020 of which only 65 were informative for the systematic review. Most empirical studies comprised outcrossers (84%) and trees (67%), with few herbs (23%) and scarce annual species (2%). In weighted meta-analyses for 116 plant populations (31 studies), we did not detect significant effects in the magnitude of effect sizes for the Sp statistic among undisturbed, degraded and fragmented habitats. Results showed significant effects for seed dispersal vectors, but not for pollination. Overall, we observed high variation among the effect sizes (not related to the goodness-of-fit of mixed models) of habitat status, pollination and seed dispersal categories, which precludes identifying biological trends on the Sp statistic. More empirical studies are needed that contrast multiple plant populations in disturbed versus undisturbed habitats, and by increasing the taxonomic groups, such as herbs and annual plants.

Quantifying the Morphology and Mechanisms of Cancer Progression in 3D In-Vitro Environments: Integrating Experiments and Multiscale Models.

Mathematical models of cancer growth have become increasingly more accurate both in the space and time domains. However, the limited amount of data typically available has resulted in a larger number of qualitative rather than quantitative studies. In the present study, we provide an integrated experimental-computational framework for the quantification of the morphological characteristics and the mechanistic modelling of cancer progression in 3D environments. The proposed framework allows for the calibration of multiscale, spatiotemporal models of cancer growth using state-of-the-art 3D cell culture data, and their validation based on the resulting experimental morphological patterns using spatial point-pattern analysis techniques. We applied this framework to the study of the development of Triple Negative Breast Cancer cells cultured in Matrigel scaffolds, and validated the hypothesis of chemotactic migration using a multiscale, hybrid Keller-Segel model. The results revealed transient, non-random spatial distributions of cancer cells that consist of clustered, and dispersion patterns. The proposed model was able to describe the general characteristics of the experimental observations and suggests that chemotactic migration together with random motion was found to be a plausible mechanism leading to accumulation, during the examined time period of development. The developed framework enabled us to pursue two goals; first, the quantitative description of the morphology of cancer growth in 3D cultures using point-pattern analysis, and second, the relation of tumour morphology with underlying biophysical mechanisms that govern cancer growth and migration.

Morphometric trends and implications for the formation of araneiform clusters

Araneiforms are an exotic type of feature exclusive to the Martian south polar terrain which have no known direct Earth analog. The dilation and recession of the seasonal CO2 ice deposit has long been hypothesized to be responsible for their gradual formation. However, high south polar latitude araneiforms have not been observed to form or extend in the present day and it is unclear whether they are growing below the limits of high resolution imagery, or whether they formed in a paleoclimate. Furthermore, it is unclear what physical factors govern the distinct araneiform morphologies, which often appear in discrete ‘clusters’, showing non-random spatial distribution. While qualitative observations of morphology have been reported, there has been a paucity of quantitative measurements of the many physical controls that govern araneiform activity and morphology. Here we present the results of a survey designed to initiate a quantitative morphometric approach to exploring some of the factors which may influence araneiform morphologies. We survey distinct clusters within 3 sites in the Martian south polar regions representing unique araneiform morphologies ranging from ‘fat’ to ‘thin’ to starburst' in order to test the relationship between vent spacing and diameter to morphology found in experimental results. Using the diameters of their central pits as proxies for their starting vent diameters, we find that the level of branching of these dendritic features appears to be correlated with (i) inferred vent spacing and (ii) inferred vent diameter. We suggest that the individual araneiforms within such distinct clusters may have formed contemporaneously, and that vent geometry reflects at least one control on their distinct morphologies. We surveyed and measured araneiforms in three HiRISE images and we have observed and characterized new morphologies at eight sites in HiRISE and CTX images between lat=-87.521°N and lon=162.39°E and lat=-74.7°N, lon=168.41°E in order to investigate if there are any trends in araneiform morphology with latitude. For the sites we studied, we find no discernable relationship between morphology and latitude, though we caution that a more extended survey is needed to confirm this observation on the broader scale. Additionally, from this survey, we report six new araneiform morphologies; ‘fan’, ‘linear’, ‘spiky’, ‘segmented’, ‘flowing’ and ‘sunflower’.

Single-molecule and super-resolved imaging deciphers membrane behavior of onco-immunogenic CCR5.

The ability of tumors to establish a pro-tumorigenic microenvironment is an important point of investigation in the search for new therapeutics. Tumors form microenvironments in part by the "education" of immune cells attracted via chemotactic axes such as that of CCR5-CCL5. Further, CCR5 upregulation by cancer cells, coupled with its association with pro-tumorigenic features such as drug resistance and metastasis, has suggested CCR5 as a therapeutic target. However, with several conformational "pools" being reported, phenotypic investigations must be capable of unveiling conformational heterogeneity. Addressing this challenge, we performed super-resolution structured illumination microscopy (SIM) and single molecule partially TIRF-coupled HILO (PaTCH) microscopy of CCR5 in fixed cells. SIM data revealed a non-random spatial distribution of CCR5 assemblies, while Intensity-tracking of CCR5 assemblies from PaTCH images indicated dimeric sub-units independent of CCL5 perturbation. These biophysical methods can provide important insights into the structure and function of onco-immunogenic receptors and many other biomolecules.

Assessment of the stream invertebrate -diversity along an elevation gradient using a bidimensional null model analysis.

β‐Diversity, commonly defined as the compositional variation among localities that links local diversity (α‐diversity) and regional diversity (γ‐diversity), can arise from two different ecological phenomena, namely the spatial species turnover (i.e., species replacement) and the nestedness of assemblages (i.e., species loss). However, any assessment that does not account for stochasticity in community assembly could be biased and misinform conservation management. In this study, we aimed to provide a better understanding of the overall ecological phenomena underlying stream β‐diversity along elevation gradients and to contribute to the rich debate on null model approaches to identify nonrandom patterns in the distribution of taxa. Based on presence‐absence data of 78 stream invertebrate families from 309 sites located in the Swiss Alpine region, we analyzed the effect size of nonrandom spatial distribution of stream invertebrates on the β‐diversity and its two components (i.e., turnover and nestedness). We used a modeling framework that allows exploring the complete range of existing algorithms used in null model analysis and assessing how distribution patterns vary according to an array of possible ecological assumptions. Overall, the turnover of stream invertebrates and the nestedness of assemblages were significantly lower and higher, respectively, than the ones expected by chance. This pattern increased with elevation, and the consistent trend observed along the altitudinal gradient, even in the most conservative analysis, strengthened our findings. Our study suggests that deterministic distribution of stream invertebrates in the Swiss Alpine region is significantly driven by differential dispersal capacity and environmental stress gradients. As long as the ecological assumptions for constructing the null models and their implications are acknowledged, we believe that they still represent useful tools to measure the effect size of nonrandom spatial distribution of taxa on β‐diversity.

Detection and Spatiotemporal Analysis of In-vitro 3D Migratory Triple-Negative Breast Cancer Cells.

The invasion of cancer cells into the surrounding tissues is one of the hallmarks of cancer. However, a precise quantitative understanding of the spatiotemporal patterns of cancer cell migration and invasion still remains elusive. A promising approach to investigate these patterns are 3D cell cultures, which provide more realistic models of cancer growth compared to conventional 2D monolayers. Quantifying the spatial distribution of cells in these 3D cultures yields great promise for understanding the spatiotemporal progression of cancer. In the present study, we present an image processing and segmentation pipeline for the detection of 3D GFP-fluorescent triple-negative breast cancer cell nuclei, and we perform quantitative analysis of the formed spatial patterns and their temporal evolution. The performance of the proposed pipeline was evaluated using experimental 3D cell culture data, and was found to be comparable to manual segmentation, outperforming four alternative automated methods. The spatiotemporal statistical analysis of the detected distributions of nuclei revealed transient, non-random spatial distributions that consisted of clustered patterns across a wide range of neighbourhood distances, as well as dispersion for larger distances. Overall, the implementation of the proposed framework revealed the spatial organization of cellular nuclei with improved accuracy, providing insights into the 3 dimensional inter-cellular organization and its progression through time.

Spatial Variations and Determinants of Anemia among Under-five Children in Nepal, DHS (2006-2016).

Anemia among under-five children is the major health problem in Nepal. The lack of nutritional supplementation and lack of healthcare facilities are influential factors of anemia. Thus, the main objective of this study is to explore spatial variations and determinants of anemia among under-five children in Nepal. Nepal Demographic and Health Survey (NDHS) data from 2006 to 2016 were used in this study, which includes: household and individual-level data of 8555 under-five children, whose anemia was measured. In addition, a total of 260 (2006), 281 (2011), and 383 DHS clusters (2016) were taken in consideration for spatial analysis. The overall prevalence of anemia was 48.9%, 46.4%, and 52.2% in 2006, 2011, and 2016 respectively. The spatial analysis revealed a nonrandom spatial distribution, where statistically significant hotspots and coldspots were detected in different parts of the country. The results also identified mother’s age, mother’s educational level, socioeconomic status of household, number of under-5 children, household size, birth weight, underweight, stunting, diarrhea, and fever as associated factors of anemia among under-5 children. These findings may provide assistance to concerned health officials in adopting anemia-related programs and policies to address the anemia problems that plague Nepalese children under the age of five.

Clusters of preterm live births and respiratory distress syndrome-associated neonatal deaths: spatial distribution and cooccurrence patterns

BackgroundPrematurity and respiratory distress syndrome (RDS) are strongly associated. RDS continues to be an important contributor to neonatal mortality in low- and middle-income countries. This study aimed to identify clusters of preterm live births and RDS-associated neonatal deaths, and their cooccurrence pattern in São Paulo State, Brazil, between 2004 and 2015. MethodsPopulation-based study of all live births with gestational age ≥ 22 weeks, birthweight ≥ 400 g, without congenital anomalies from mothers living in São Paulo State, Brazil, during 2004–2015. RDS-associated neonatal mortality was defined as deaths < 28 days with ICD-10 codes P22.0 or P28.0. RDS-associated neonatal mortality and preterm live births rates per municipality were submitted to first- and second-order spatial analysis before and after smoothing using local Bayes estimates. Spearman test was applied to identify the correlation pattern between both rates.ResultsSix hundred forty-five thousand two hundred seventy-six preterm live births and 11,078 RDS-associated neonatal deaths in São Paulo State, Brazil, during the study period were analyzed. After smoothing, a non-random spatial distribution of preterm live births rate (I = 0.78; p = 0.001) and RDS-associated neonatal mortality rate (I = 0.73; p = 0.001) was identified. LISA maps confirmed clusters for both, with a negative correlation (r = -0.24; p = 0.0000). Clusters of high RDS-associated neonatal mortality rates overlapping with clusters of low preterm live births rates were detected. ConclusionsAsymmetric cluster distribution of preterm live births and RDS-associated neonatal deaths may be helpful to indicate areas for perinatal healthcare improvement.

Abstract 2734: Integrating hybrid spatiotemporal models and multiscale data for the study of cancer progression in 3D cultures

Abstract Tumour progression consists of various stages including migration to the surrounding tissues, leading to metastasis [1]. In this work, we investigate the multiscale quantitative characteristics of the spatial organization and migration of cancer in 3D cultures. For this study, we combined 3D cell culture experiments of Triple Negative Breast Cancer (TNBC) cells, hybrid spatiotemporal models, and longitudinal RNA-sequencing data analysis. The experiments included two experimental conditions; simple growth experiments, and experiments of growth in presence of the migrastatic drug Paclitaxel. The spatial distributions of the cells enabled us to calibrate and validate a hybrid Keller-Segel model, incorporated into a novel computational framework capable of interpreting the relation between morphological patterns and the underlying mechanisms of cancer growth [2]. The RNA-seq data included different time-points with and without treatment. The results suggested that cancer cells exhibited biased movement towards the bottom of the space, a movement that was inhibited in the presence of Paclitaxel. The calibrated model was able to describe the overall characteristics of the experimental observations, and suggested that cancer cells exhibited chemotactic migration and cell accumulation, as well as random motion throughout the period of development. The spatial pattern analysis revealed transient, non-random spatial distributions of cancer cells that consisted of clustered patterns across a wide range of neighbourhood distances, as well as dispersion for larger distances. The RNA-seq data exhibited coherence with the chemotactic migration hypothesis of the mathematical model, indicating significant under-representation of the Gene Ontology (GO) terms related to chemotactic migration in presence of the migrastatic drug. Overall, this study provided an insightful quantitative characterization of the spatiotemporal organization and progression of TNBC cells in 3D cultures. We anticipate that these developments will enable us to expand our studies to more realistic conditions, including the introduction of heterogeneic cell populations.

The Association of Laryngeal Position on Videolaryngoscopy and Time Taken to Intubate Using Spatial Point Pattern Analysis of Prospectively Collected Quality Assurance Data.

During videolaryngoscopy (VL), the larynx appears within the defined area of the video screen, and its location can be measured as a point within this space. Spatial statistics offer methods to explore the relationship between location data and associated variables of interest. The aims of this study were to use spatial point pattern analysis to explore if the position of the larynx on VL is associated with longer times to intubate, increased risk of a needing >1 intubation attempt, or percentage of glottic opening. Quality assurance data and clinical notes from all prehospital intubations using C-MAC Pocket Monitor with CMAC-4 blade (Karl Storz) from January 1, 2018, to July 31, 2020, were reviewed. We extracted 6 measurements corresponding to the time taken to obtain the initial and then best laryngeal view, time to manipulate a bougie, and time to place the endotracheal tube, as well a percentage of glottic opening and a number of intubation attempts. Larynx location was the middle of the base of glottis, in cm from the left and bottom on the C-MAC screen. Two plots were produced to summarize the base of glottis location and time to perform each time component of intubation. Next, a cross mark function and a maximum absolute deviation hypothesis test were performed to assess the null hypotheses that the spatial distributions were random. The association between glottis location and >1 intubation attempt was assessed by a spatial relative risk plot. Of 619 eligible intubations, 385 had a video for analysis. The following time variables had a nonrandom spatial distribution with a tendency for longer times when the larynx was off-center to the top or right of the screen: laryngoscope passing from teeth to glottis, glottis first view to best view of the larynx, time from bougie appearing to being placed in the cords, and overall time from teeth to endotracheal tube passing through cords. There was no increased relative risk for >1 intubation attempt. Spatial point pattern analysis identified a relationship between the position of the larynx during VL and prolonged intubation times. We did not find a relationship between larynx location and >1 attempt. Whether the location of the larynx on the screen is a marker for difficult VL or if optimizing the larynx position to the center of the screen improves intubation times would require further prospective studies.

Variation of Clumping Index With Zenith Angle for Forest Canopies

Canopy clumping index (CI) characterizes the extent of the nonrandom spatial distribution of foliage elements within a canopy and is critical for determining the radiative transfer, photosynthesis, and transpiration processes in the canopy. It is widely perceived that CI increases with zenith angle (θ), because between-crown gaps decrease in size and number with increasing θ. In this study, we demonstrate that this is not always true. Analytical equations between CI and θ are first developed based on widely-used forest canopy gap fraction theories. The results show that the zenith angular variation of CI is closely related to crown projected area or crown shapes (i.e., the ratio of the crown height to its diameter, RHD): CI increases with θ for canopies with “tower” crowns (RHD > 1), but decreases with θ for “umbrella” crowns (RHD < 1) and does not vary much with θ for “sphere” crowns (RHD = 1). These results are validated in a LargE-Scale remote sensing data and image Simulation framework (LESS) platform, and published datasets including the measurements in field and RAMI forest stands. The findings are essential for the derivation of angular integrated (hemispherical) CI from <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> measurements and multi-angular remote sensing.

Using fractal dimension to correct clumping effect in leaf area index measurement by digital cover photography

The leaf area index (LAI), defined as one-half of the total green leaf area per unit horizontal ground surface area, is a key parameter in agriculture, forestry, ecology, and other fields. The clumping index (CI) accounts for the nonrandom spatial distribution of the foliage elements in the canopy, thereby considerably influencing the accuracy of LAI estimation with optical field-based instruments. Most of the traditional clumping effect correction methods for LAI measurements are based on the theory developed for one-dimensional (1D) data of the vegetation canopy. The development of new methods remains necessary for LAI measurement with two-dimensional (2D) data, including images from digital cover photography (DCP). We found that the fractal dimension (FD) of a 2D ground-based DCP image is an effective tool for correcting the clumping effect and estimating the LAI. The universal formula was derived to describe the relationship between the LAI and FD for randomly distributed leaves using the box-counting method (BCM) and the Boolean model. For the clumped leaves, the universal formula is related to the FD, LAI, and CI. The LAI and CI can be calculated with the FD and gap probability derived from DCP images. Eighteen simulated scenes of different vegetation structure patterns, three realistic canopy scenes of the fourth phase of the radiative transfer model intercomparison (RAMI), and field-measured data acquired from 5 plots in 4 temporal phases were provided to validate the method. The results showed good agreement with the reference (R2 = 0.93 and RMSE = 0.46 for simulated data; uncertainty from 0.31 to 1.05 for realistic canopy; R2 = 0.85 and RMSE = 0.34 for field-measured data). This validation with downward DCP images shows that the proposed FD method assesses the clumping effect more thoroughly compared to the clumping effect correction methods originally designed for 1D data. The FD method is expected to improve the measurement accuracy of LAI with DCP images, especially for heterogeneous canopies.

Social segregation and lethal police violence in the city of São Paulo, Brazil (2014-2015).

We aimed to investigate how lethal police violence (LPV) in the City of São Paulo (CSP), Brazil, is associated with socioeconomic development when we consider the victims' place of residence and the locations of the fatal injuries. The spatial distribution of lethal police violence rate (LPVR) and its association with the human development index (HDI) was investigated using the Moran's I (Global and Bivariate Local). Between 2014 and 2015 we found 403 police victims in the Health database and 794 victims in the Security Department. We found a non-random spatial distribution of the LPV considering the victim's place of residence (I=+0.12; p<0.001) and the locations where the fatal injuries were inflicted (I=+0.07; p<0.001). We found a negative association between LPVR and the HDI of the place of residence (I=-0.10; p<0.001) and a positive association between LPVR and the HDI of the locations of the fatal injuries (I=+0.02; p<0.001). The results point to different dynamics of LPV in CSP. High mortality clusters are found in areas with lower HDI, when considering the victim's address, and in areas with higher HDI, when considering the address of the violent events. LPV impacts young blacks, poorly educated residents of outskirts informing us about patterns of social segregation.

Skin-resident immune cells actively coordinate their distribution with epidermal cells during homeostasis.

Organs consist of multiple cell types that ensure proper architecture and function. How different cell types coexist and interact to maintain their homeostasis in vivo remains elusive. The skin epidermis comprises mostly epithelial cells, but also harbours Langerhans cells (LCs) and dendritic epidermal T cells (DETCs). Whether and how distributions of LCs and DETCs are regulated during homeostasis is unclear. Here, by tracking individual cells in the skin of live adult mice over time, we show that LCs and DETCs actively maintain a non-random spatial distribution despite continuous turnover of neighbouring basal epithelial cells. Moreover, the density of epithelial cells regulates the composition of LCs and DETCs in the epidermis. Finally, LCs require the GTPase Rac1 to maintain their positional stability, density and tiling pattern reminiscent of neuronal self-avoidance. We propose that these cellular mechanisms provide the epidermis with an optimal response to environmental insults.

Retracing Hotbeds of the 1918–19 Influenza Pandemic. Spatial Differences in Seasonal Excess Mortality in the Netherlands

A century ago, the 1918–19 influenza pandemic swept across the globe, taking the lives of over 50 million people. We use data from the Dutch civil registry to show which regions in the Netherlands were most affected by the 1918–19 pandemic. We do so for the entire 1918 year as well as the first, second, and third wave that hit the Netherlands in summer 1918, autumn 1918, and winter 1919. Our analyses show that excess mortality was highest in Oost-Brabant, Zuid-Limburg, Noord-Holland, and Drenthe, Groningen, and Overijssel, whereas excess mortality was low in Zuid-Beveland, the Utrechtse Heuvelrug, and the Achterhoek. Furthermore, neighboring municipalities resembled one another in how severely they were affected, but only for the second wave that hit the Netherlands in autumn 1918. This non-random spatial distribution of excess mortality in autumn 1918 suggests that regional differences affected the spread of the disease.

Nonrandom spatial distribution of Neotropic Cormorants (Phalacrocorax brasilianus) along a coastal highway in Lima, Peru.

Neotropic Cormorants (Phalacrocorax brasilianus) are common seabirds along the Peruvian coast. They frequently perch on trees, poles and port structures in urban areas, producing guano that builds up in areas of high levels of human activity. Hundreds of Neotropic Cormorants rest on lighting poles and telephone cables along a 12.7 km highway in the coastal strip of the city of Lima, Peru. We hypothesized that the distribution of the cormorants along this highway is clustered and could be associated with physical features of both the coast and the adjacent marine area. Fortnightly or monthly surveys were performed from July 2018 to March 2020 in the Circuito de Playas de la Costa Verde highway. At each survey, cormorants were counted per lighting pole and adjacent telephone cables (collectively, “pole-cable”) at four count hours (0600 h, 1000 h, 1400 h and 1800 h). Our results revealed that daily bird numbers varied from 46 to 457 individuals and that only 17% of the total number of pole-cables (N = 651) was occupied once by at least one individual. The number of cormorants also varied between count hours within the same day (higher numbers at 1000 h and 1400 h). Birds were clustered into a maximum of five hotspots along the highway. According to a model selection criterion, higher numbers of cormorants on pole-cables were associated mainly to a closer distance from these structures to the shoreline and to the surf zone, suggesting that Neotropic Cormorants may select such pole-cables as optimal sites for sighting and receiving cues of prey availability. Based on the results, the use of nonlethal deterrents and the relocation of these birds to other perching structures on nearby groynes could be the most suitable management proposal for the problems caused by their feces.