Composition of Carbon Clusters in Implanted Silicon Using Atom Probe Tomography

Atom probe tomography was employed to observe and derive the composition of carbon clusters in implanted silicon. This value, which is of interest to the microelectronic industry when considering ion implantation defects, was estimated not to exceed 2 at%. This measurement has been done by fitting the distribution of first nearest neighbor distances between monoatomic carbon ions (C+ and C2+). Carbon quantification has been considerably improved through the detection of molecular ions, using lower electric field conditions as well as equal proportions of 12C and 13C. In these conditions and using another quantification method, we have shown that the carbon content in clusters approaches 50 at%. This result very likely indicates that clusters are nuclei of the SiC phase.

Spatial Movement Patterns and Local Co-Occurrence of Nutria Individuals in Association with Habitats Using Geo-Self-Organizing Map (Geo-SOM)

Nutrias (Myocastor coypus) were imported to South Korea for farming in 1985; individuals escaped captivity and established wild populations in natural ecosystems in the late 1990s. Numerous studies have focused on their monitoring and management; however, information on the continuous movement of individuals is not available. In this study, telemetry data from field conditions were used to identify the nearest-neighbor distances of individuals in association with environmental factors, including plant type, land cover, and biological parameters. The minimum nearest-neighbor distances for the different sexes were, overall, according to the minimum distances for the same sex. Local co-occurrences of individuals, either of the same or different sex, were seasonal. Tall grasslands, followed by herbaceous vegetation, were associated with the co-occurrence of different sexes. Conversely, floating-leaved hydrophytes, followed by xeric herbaceous vegetation, were correlated with the co-occurrence of the same sex. Local female–male co-occurrences were negatively associated with male–male co-occurrences but not with female–female co-occurrences, suggesting male dominance in group formations. Movement and co-occurrence information extracted using Geo-self-organizing maps furthers our understanding of population dispersal and helps formulate management strategies for nutria populations.

Stomatal Arrangement Pattern: A New Direction to Explore Plant Adaptation and Evolution

The arrangement patterns of stomata on the leaf surface influence water loss and CO2 uptake via transportation and diffusion between stomata, the sites of photosynthesis, and vasculature. However, the quantification of such patterns remains unclear. Based on the distance between stomata, we developed three independent indices to quantify stomatal arrangement pattern (SAP). “Stomatal evenness” was used to quantify the regularity of the distribution of stomata based on a minimum spanning tree, “stomatal divergence” described the divergence in the distribution of stomata based on their distances from their center of gravity, and “stomatal aggregation” was used to quantitatively distinguish the SAP as clustered, random, or regularly distributed based on the nearest-neighbor distances. These three indices address the shortcoming of stomatal density that only describes “abundance” and may, collectively, have a better capacity to explore crop development, plant adaptation and evolution, and potentially ultimately enable a more accurate reconstruction of the palaeoclimate.

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

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.

Abstract 14916: Clonal Analysis of the Neonatal Mouse Heart Using Nearest Neighbor Modeling

Introduction: Heart regeneration has been proposed as a treatment for heart failure. However, the challenge of detecting bona fide heart regeneration has complicated the validation of potential regenerative factors. We sought to develop a method for quantifying cardiomyogenesis in the mouse heart using multicolor lineage tracing. Hypothesis: We hypothesized that multicolor lineage tracing in combination with modeling of nearest neighbor distances could be used to quantify clonal expansion of cardiomyocytes (CMs) during growth and regeneration. Methods: Myh6- MerCreMer ; R26R-Rainbow bitransgenic mice underwent cryoinjury (CI) or sham injury on postnatal day 1 (P1). Tamoxifen was then administered such that limited numbers of CMs were randomly labeled with mCerulean, mOrange, or mCherry fluorophores. Hearts were collected at 21 days post CI. We analyzed a total of 81 sections, across 6 hearts (3 with sham injury and 3 with cryoinury). Images of entire cardiac sections were manually segmented to generate positional information for each labeled CM. Results: We used the nearest neighbor distributions of CMs carrying the same fluorophore and CMs carrying different fluorophores to develop a Bayesian model for estimating the probability that two CMs are clonally related. We found that, across a range of recombination efficiency, CMs carrying the same fluorophore within 30 μm are likely to be clonally related. By classifying CMs based on this distance threshold, we were able to confirm that clonally related CMs are smaller than non-clonally related CMs (165.20 ± 13.79 μm 2 vs 252.37 ± 20.51 μm 2 , p = 0.007, Welch t-test). We also confirmed that rates of cardiomyogenesis in cryoinjured and sham injured hearts are approximately the same (8.57 ± 2.69 % in cryoinjured hearts vs 9.45 ± 1.23 % in sham hearts, p=0.788). Conclusions: We have developed a robust and objective approach for quantifying cardiomyogenesis in the mouse heart. This method can be applied to studies of heart regeneration and can also be adapted to other tissues.

Conformity in the collective: differences in hunger affect individual and group behavior in a shoaling fish

Animal groups are often composed of individuals that vary according to behavioral, morphological, and internal state parameters. Understanding the importance of such individual-level heterogeneity to the establishment and maintenance of coherent group responses is of fundamental interest in collective behavior. We examined the influence of hunger on the individual and collective behavior of groups of shoaling fish, x-ray tetras (Pristella maxillaris). Fish were assigned to one of two nutritional states, satiated or hungry, and then allocated to 5 treatments that represented different ratios of satiated to hungry individuals (8 hungry, 8 satiated, 4:4 hungry:satiated, 2:6 hungry:satiated, 6:2 hungry:satiated). Our data show that groups with a greater proportion of hungry fish swam faster and exhibited greater nearest neighbor distances. Within groups, however, there was no difference in the swimming speeds of hungry versus well-fed fish, suggesting that group members conform and adapt their swimming speed according to the overall composition of the group. We also found significant differences in mean group transfer entropy, suggesting stronger patterns of information flow in groups comprising all, or a majority of, hungry individuals. In contrast, we did not observe differences in polarization, a measure of group alignment, within groups across treatments. Taken together these results demonstrate that the nutritional state of animals within social groups impacts both individual and group behavior, and that members of heterogenous groups can adapt their behavior to facilitate coherent collective motion.