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ALZOUBI, KHALED M., PENG-JUN WAN, and OPHIR FRIEDER. "MAXIMAL INDEPENDENT SET, WEAKLY-CONNECTED DOMINATING SET, AND INDUCED SPANNERS IN WIRELESS AD HOC NETWORKS." International Journal of Foundations of Computer Science 14, no. 02 (2003): 287–303. http://dx.doi.org/10.1142/s012905410300173x.
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A maximal independent set (MIS) S for a graph G is an independent set and no proper superset of S is also independent. A set S is dominating if each node in the graph is either in S or adjacent to one of the nodes in S. The subgraph weakly induced by S is the graph G′ such that each edge in G′ has at least one end point in S. A set S is a weakly-connected dominating set (WCDS) of G if S is dominating and G′ is connected. G′ is a sparse spanner if it has linear edges. The nodes of WCDS have been proposed in the literature as clusterheads for clustered wireless ad hoc networks. In this paper, we present two distributed algorithms for constructing a WCDS for wireless ad hoc networks in linear time. The first algorithm has an approximation ratio of 5, and requires O(n log n) messages, while the second algorithm has a larger approximation ratio, and requires only O(n) messages. Both of these algorithms are used to obtain sparse spanners. The spanner obtained by the second algorithm has a topological dilation of 3, and a geometric dilation of 6. Both of these algorithms are based on the construction of a MIS. The first algorithm requires the construction of a spanning tree. The second algorithm is fully localized, and does not depend on the spanning tree, which makes the maintenance of the WCDS simpler, and guarantees the maintenance of the same approximation ratio.
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Bhatt, Abhay G., and Rahul Roy. "On a random directed spanning tree." Advances in Applied Probability 36, no. 1 (2004): 19–42. http://dx.doi.org/10.1239/aap/1077134462.
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We study the asymptotic properties of a minimal spanning tree formed by n points uniformly distributed in the unit square, where the minimality is amongst all rooted spanning trees with a direction of growth. We show that the number of branches from the root of this tree, the total length of these branches, and the length of the longest branch each converges weakly. This model is related to the study of record values in the theory of extreme-value statistics and this relation is used to obtain our results. The results also hold when the tree is formed from a Poisson point process of intensity n in the unit square.
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Bhatt, Abhay G., and Rahul Roy. "On a random directed spanning tree." Advances in Applied Probability 36, no. 01 (2004): 19–42. http://dx.doi.org/10.1017/s0001867800012854.
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We study the asymptotic properties of a minimal spanning tree formed by n points uniformly distributed in the unit square, where the minimality is amongst all rooted spanning trees with a direction of growth. We show that the number of branches from the root of this tree, the total length of these branches, and the length of the longest branch each converges weakly. This model is related to the study of record values in the theory of extreme-value statistics and this relation is used to obtain our results. The results also hold when the tree is formed from a Poisson point process of intensity n in the unit square.
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Mayliana, Mayliana. "Optimasi Jaringan dengan Spanning Tree untuk Congestion Management." ComTech: Computer, Mathematics and Engineering Applications 5, no. 1 (2014): 53. http://dx.doi.org/10.21512/comtech.v5i1.2582.
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A proper network optimization is needed to deal with problems on the network and to minimize latency in the data flow in a dense network. The data stream is directed into the right channels so that the optimal network speed and latency can be minimized. Spanning tree is one of the algorithms that can be used. The purpose of the Spanning tree is to prevent and reduce the loops in the network by negotiating free path and as well as to increase network uptime through redundancy (back-up). To comprehend spanning tree, the first important thing to know is how bridges and switches perform their functions. The more switches used, the use of the spanning tree becomes more important. With the spanning tree protocol, a broadcast storm can be prevented that can achieved network optimization.
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Penrose, Mathew D. "Extremes for the minimal spanning tree on normally distributed points." Advances in Applied Probability 30, no. 3 (1998): 628–39. http://dx.doi.org/10.1239/aap/1035228120.
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Let n points be placed independently in ν-dimensional space according to the standard ν-dimensional normal distribution. Let Mn be the longest edge-length of the minimal spanning tree on these points; equivalently let Mn be the infimum of those r such that the union of balls of radius r/2 centred at the points is connected. We show that the distribution of (2 log n)1/2Mn - bn converges weakly to the Gumbel (double exponential) distribution, where bn are explicit constants with bn ~ (ν - 1)log log n. We also show the same result holds if Mn is the longest edge-length for the nearest neighbour graph on the points.
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Penrose, Mathew D. "Extremes for the minimal spanning tree on normally distributed points." Advances in Applied Probability 30, no. 03 (1998): 628–39. http://dx.doi.org/10.1017/s000186780000851x.
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Let n points be placed independently in ν-dimensional space according to the standard ν-dimensional normal distribution. Let M n be the longest edge-length of the minimal spanning tree on these points; equivalently let M n be the infimum of those r such that the union of balls of radius r/2 centred at the points is connected. We show that the distribution of (2 log n)1/2 M n - b n converges weakly to the Gumbel (double exponential) distribution, where b n are explicit constants with b n ~ (ν - 1)log log n. We also show the same result holds if M n is the longest edge-length for the nearest neighbour graph on the points.
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Dereniowski, Dariusz. "Minimum vertex ranking spanning tree problem for chordal and proper interval graphs." Discussiones Mathematicae Graph Theory 29, no. 2 (2009): 253. http://dx.doi.org/10.7151/dmgt.1445.
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Honma, Hirotoshi, Yoko Nakajima, Shino Nagasaki, and Atsushi Sasaki. "An Optimal Parallel Algorithm for Constructing a Spanning Tree on Proper Circle Trapezoid Graphs." Journal of Applied Mathematics and Physics 06, no. 08 (2018): 1649–58. http://dx.doi.org/10.4236/jamp.2018.68141.
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FERRAGINA, PAOLO, and FABRIZIO LUCCIO. "THREE TECHNIQUES FOR PARALLEL MAINTENANCE OF A MINIMUM SPANNING TREE UNDER BATCH OF UPDATES." Parallel Processing Letters 06, no. 02 (1996): 213–22. http://dx.doi.org/10.1142/s0129626496000212.
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In this paper we provide three simple techniques to maintain in parallel the minimum spanning tree of an undirected graph under single or batch of edge updates (i.e., insertions and deletions). Our results extend the use of the sparsification data structure to the EREW PRAM model. For proper values of the batch size, our algorithms require less time and work than the best known dynamic parallel algorithms.
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Sisto, Alessandro. "Contracting elements and random walks." Journal für die reine und angewandte Mathematik (Crelles Journal) 2018, no. 742 (2018): 79–114. http://dx.doi.org/10.1515/crelle-2015-0093.
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Abstract We define a new notion of contracting element of a group and we show that contracting elements coincide with hyperbolic elements in relatively hyperbolic groups, pseudo-Anosovs in mapping class groups, rank one isometries in groups acting properly on proper {\mathrm{CAT}(0)} spaces, elements acting hyperbolically on the Bass–Serre tree in graph manifold groups. We also define a related notion of weakly contracting element, and show that those coincide with hyperbolic elements in groups acting acylindrically on hyperbolic spaces and with iwips in {\mathrm{Out}(F_{n})} , {n\geq 3} . We show that each weakly contracting element is contained in a hyperbolically embedded elementary subgroup, which allows us to answer a problem in [16]. We prove that any simple random walk in a non-elementary finitely generated subgroup containing a (weakly) contracting element ends up in a non-(weakly-)contracting element with exponentially decaying probability.
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Cai, Shuiming, Peipei Zhou, and Zengrong Liu. "Effects of Time-Varying Impulses on the Synchronization of Delayed Dynamical Networks." Abstract and Applied Analysis 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/212753.
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The effects of time-varying impulses on the synchronization of a class of general complex delayed dynamical networks are investigated. Different from the existing works, the impulses discussed here are time-varying, and both synchronizing and desynchronizing impulses are considered in the network model simultaneously. Moreover, the network topology is assumed to be directed and weakly connected with a spanning tree. By using the comparison principle, some simple yet generic globally exponential synchronization criteria are derived. It is shown that besides impulse strengths and impulsive interval, the obtained criteria are also closely related with topology structure of the network. Finally, numerical examples are given to demonstrate the effectiveness of the theoretical results.
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CLAUSI, MIRELLA, DIEGO LEONE, and SERGEI E. SPIRIDONOV. "HAPLOTYPE DIVERSITY OF STEINERNEMA FELTIAE (NEMATODA: STEINERNEMATIDAE) IN EURASIA." Redia 103 (December 1, 2020): 133–36. http://dx.doi.org/10.19263/redia-103.20.21.
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Phylogenetic analysis of ITS rDNA sequences of the entomopathogenic nematode Steinernema feltiae Filipjev, 1934 (Wouts, Mráček, Gerdin and Bedding, 1982) was used to infer intraspecific genetic variability of this rhabditid nematode. Nucleotide intraspecific differences among S. feltiae isolates reached the level of 19 base pairs per ITS rDNA region, i.e. up to 2.9%. Several weakly or moderately supported intraspecific clades were detected. Sicilian and Swiss isolates of S. feltiae were found clustering together. Swiss strain ‘St. Bernard’ has been isolated on the St. Bernardino mountain pass in Switzerland in 2000. Phylogenetic relationships among S. feltiae isolates were inferred by using three different methods (maximum parsimony, neighbor joining and maximum likelihood). The topologies of the phylogenetic trees were identical and thus only ML tree is presented. ML tree revealed that S. feltiae isolates from Israel and Armenia grouped at the basal position of the tree, while in the spanning network obtained with POPART software, Iranian and Ukrainian isolates were the closest to the outgroup. In all methods of analyses, the European and Siberian strains of S. feltiae occupied terminal positions. Thus, further studies on the intraspecific genetic variability of entomopathogenic nematodes is needed.
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Graumlich, Lisa J. "Response of tree growth to climatic variation in the mixed conifer and deciduous forests of the upper Great Lakes region." Canadian Journal of Forest Research 23, no. 2 (1993): 133–43. http://dx.doi.org/10.1139/x93-020.
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Tree-ring data were used to define regional tree-growth anomalies (i.e., recurring spatial patterns of growth that differ from long-term averages) for 11 species growing in a network of sites spanning the deciduous and mixed hardwood–conifer forest boundary in the upper Great Lakes region. Tree-ring samples were collected at 11 sites that are classified as mesic to dry–mesic based on species composition. At each stand at least 20 trees were sampled of each species dominant in the canopy, resulting in one to five species collections per stand and 31 chronologies in total. Principal component analysis was used to define the common variance among the chronologies. Three components explain 57.4% of the variation among the chronologies, indicating that common patterns of tree growth exist within the multispecies network. Component loadings indicate that (i) species to species variation is more important than site to site variation and (ii) species can be segregated into distinct groups based on their common patterns of growth through time. Correlations between the three-component-score time series and climatic data indicate that growth anomaly patterns are weakly, but significantly, correlated with growing-season temperature and precipitation variables. Extreme climatic events (i.e., greater than 1 SD above or below the mean) are very important in generating differential growth rates among the species sampled.
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Zhu, Weiping, Hongliang Lu, Xiaohui Cui, and Jiannong Cao. "A Distributed Relation Detection Approach in the Internet of Things." Mobile Information Systems 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/4789814.
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In the Internet of Things, it is important to detect the various relations among objects for mining useful knowledge. Existing works on relation detection are based on centralized processing, which is not suitable for the Internet of Things owing to the unavailability of a server, one-point failure, computation bottleneck, and moving of objects. In this paper, we propose a distributed approach to detect relations among objects. We first build a system model for this problem that supports generic forms of relations and both physical time and logical time. Based on this, we design the Distributed Relation Detection Approach (DRDA), which utilizes a distributed spanning tree to detect relations using in-network processing. DRDA can coordinate the distributed tree-building process of objects and automatically change the depth of the routing tree to a proper value. Optimization among multiple relation detection tasks is also considered. Extensive simulations were performed and the results show that the proposed approach outperforms existing approaches in terms of the energy consumption.
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Liu, Wei, Shaolei Zhou, Qingpo Wu, and Gaoyang Yin. "H∞ consensus of multi-agent systems in directed networks with Lipschitz non-linear dynamics." Transactions of the Institute of Measurement and Control 39, no. 12 (2016): 1877–84. http://dx.doi.org/10.1177/0142331216655395.
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This paper studies the H∞ consensus problem of multi-agent systems with Lipschitz non-linearities and external disturbances in a general network. The topology is just required to contain a directed spanning tree. Distributed consensus controllers are constructed based on relative states information of neighbour agents. A novel matrix decomposition based approach is introduced to analyse the H∞ consensus problem, in which the H∞ consensus problem is converted into a H∞ control problem of lower dimension system by performing a proper linear variable transformation. Finally, the effectiveness of the theoretical results is illustrated via a numerical simulation.
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ENAYAT, ALI, and JOEL DAVID HAMKINS. "ZFC PROVES THAT THE CLASS OF ORDINALS IS NOT WEAKLY COMPACT FOR DEFINABLE CLASSES." Journal of Symbolic Logic 83, no. 1 (2018): 146–64. http://dx.doi.org/10.1017/jsl.2017.75.
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AbstractIn ZFC, the class Ord of ordinals is easily seen to satisfy the definable version of strong inaccessibility. Here we explore deeper ZFC-verifiable combinatorial properties of Ord, as indicated in Theorems A & B below. Note that Theorem A shows the unexpected result that Ord is never definably weakly compact in any model of ZFC.Theorem A. Let${\cal M}$be any model of ZFC.(1)The definable tree property fails in${\cal M}$: There is an${\cal M}$-definable Ord-tree with no${\cal M}$-definable cofinal branch.(2)The definable partition property fails in${\cal M}$: There is an${\cal M}$-definable 2-coloring$f:{[X]^2} \to 2$for some${\cal M}$-definable proper class X such that no${\cal M}$-definable proper classs is monochromatic for f.(3)The definable compactness property for${{\cal L}_{\infty ,\omega }}$fails in${\cal M}$: There is a definable theory${\rm{\Gamma }}$in the logic${{\cal L}_{\infty ,\omega }}$(in the sense of${\cal M}$) of size Ord such that every set-sized subtheory of${\rm{\Gamma }}$is satisfiable in${\cal M}$, but there is no${\cal M}$-definable model of${\rm{\Gamma }}$.Theorem B. The definable ⋄Ordprinciple holds in a model${\cal M}$of ZFC iff${\cal M}$carries an${\cal M}$-definable global well-ordering.Theorems A and B above can be recast as theorem schemes in ZFC, or as asserting that a single statement in the language of class theory holds in all ‘spartan’ models of GB (Gödel-Bernays class theory); where a spartan model of GB is any structure of the form $\left( {{\cal M},{D_{\cal M}}} \right)$, where ${\cal M} \models {\rm{ZF}}$ and ${D_{\cal M}}$ is the family of${\cal M}$-definable classes. Theorem C gauges the complexity of the collection GBspa of (Gödel-numbers of) sentences that hold in all spartan models of GB.Theorem C. GBspais${\rm{\Pi }}_1^1$-complete.
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Liu, Wei, Shaolei Zhou, Shi Yan, and Gaoyang Yin. "Robust Leaderless Consensus of Uncertain Multiagent Systems with Fast Switching Topologies." Mathematical Problems in Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/810950.
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This paper investigates the robust leaderless consensus problem of uncertain multiagent systems with directed fast switching topologies. The topologies are assumed to jointly contain a directed spanning tree. Based on a special property of the graph Laplacian matrix, the consensus problem is converted into a stabilization problem by performing a proper variable transformation. Averaging method is employed for analysis. It is proved that if the topologies switch sufficiently fast and the controllers are properly designed, the robust leaderless consensus can still be achieved even when all the possible topologies are unconnected in the switching time intervals. Finally, a numerical simulation is provided to illustrate the effectiveness of the theoretical results.
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Pu, Xingcheng, and Xia Sun. "The Couple-Group Consensus of Heterogeneous Multiagent Systems with Asynchronous Switching in Cooperative-Competitive Networks." Mathematical Problems in Engineering 2023 (January 17, 2023): 1–17. http://dx.doi.org/10.1155/2023/8105727.
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This paper investigates the problem of leader-following or leaderless couple-group consensus of heterogeneous multiagent systems (HMASs) with cooperative-competitive interaction, asynchronous switching, and controller faults. Some novel protocols have been proposed to solve the couple-group consensus of the two kinds of HMASs. Compared with the existing results, asynchronous control, controller faults, leaders, and the competitive-cooperative interaction are all considered in these novel protocols. By using linear matrix inequality, graph theory, Lyapunov functional theory, and model-dependent dwell time technique (MDADT), some sufficient conditions have been gained for the leader-following or leaderless couple-group consensus of these systems. The obtained results show that the couple-group consensus of HMASs can be transformed into determining the stability of the related switching linear system. These results can also be applied to HMASs with weakly connected topology without satisfying the demand of in-degree balance, strong connectivity, or containing a spanning tree. Some simulation experiments are given to prove the validity of the obtained results.
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Mayborodin, Sergey Vyacheslavovich. "SELECTION OF OPTIMAL VARIETIES OF APPLE TREE OF DIFFERENT MATURATION DATES IN THE CONDITIONS OF THE AZOV ZONE OF THE ROSTOV REGION." Fruit growing and viticulture of South Russia 6, no. 84 (2023): 1–14. http://dx.doi.org/10.30679/2219-5335-2023-6-84-1-14.
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Currently, financial success in the market can be provided by varieties of fruit crops that have a complex of economically valuable and adaptively significant characteristics, at the same time, characterized by high yield capacity, proper presentation, transportability and the ability to long-term storage. The key to the cost-effective maintenance of an apple orchard is determined by rational technology, proper care of trees, and the correct selection of varieties. It is worth noting that the average yield capacity of apple fruits on the Don in the years before the reforms did not exceed 40-50 kg/ha. The low yield capacity is explained by the lack of an irrigation system in the orchards, the use seed, strong-growing rootstocks as the main, the rare standing of trees (250-300 tree/ha) in the orchard, an unsuccessful choice of varieties. The determination of the most suitable varieties for the selected climatic zone became the purpose of the research. So, in 2012, in the conditions of the Azov zone of the Rostov region, an intensive type orchard was planted on an area of 84 hectares, in which eight apple varieties of different ripening periods were placed. When laying the garden, mainly new varieties with increased resistance to diseases and pests were used. The rootstock of seedlings is weakly growing, vegetatively propagated M9 (paradizka 9, EM 9). Tree planting scheme is 3x1 m (3m2 /tree, 3333 tree/ha). In the course of our work, the fertility of these varieties, yield capacity, the influence of climate and temperature on trees, as well as resistance to diseases and pests were analyzed. Based on the obtained data, optimal varieties of various maturation periods for cultivation in the Azov zone of the Rostov region were established.
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Karmakar, Dhiman, Madhura Datta, and C. A. Murthy. "Intra-Class Threshold Generation in Multimodal Biometric Systems by Set Estimation Technique." International Journal of Software Science and Computational Intelligence 5, no. 3 (2013): 22–32. http://dx.doi.org/10.4018/ijssci.2013070102.
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Biometric recognition techniques attracted the researchers for the last two decades due to their many applications in the field of security. In recent times multimodal biometrics have been found to perform better, in several aspects, over unimodal biometrics. The classical approach for recognition is based on dissimilarity measure and for the sake of proper classification one needs to put a threshold on the dissimilarity value. In this paper an intra-class threshold for multimodal biometric recognition procedure has been developed. The authors' selection method of threshold is based on statistical set estimation technique which is applied on a minimal spanning tree and consisting of fused face and iris images. The fusion is performed here on feature level using face and iris biometrics. The proposed method, applied on several multimodal datasets, found to perform better than traditional ROC curve based threshold technique.
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Barman, Debaditya, and Nirmalya Chowdhury. "A Novel Approach for the Customer Segmentation Using Clustering Through Self-Organizing Map." International Journal of Business Analytics 6, no. 2 (2019): 23–45. http://dx.doi.org/10.4018/ijban.2019040102.
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Customer segmentation is the process of forming smaller groups of customers according to their characteristics. Now companies can develop proper marketing strategies for each group to get the desired results. This type of direct marketing is practiced by most organizations from the size of smallest start-up to the Fortune 500 leaders. Clustering is the ideal data mining technique for customer segmentation. In this article, the authors have proposed a clustering algorithm based on the self-organizing map and minimum spanning tree for customer segmentation. The authors have used several synthetic and real-life datasets to evaluate the clustering performance of their approach. To demonstrate the effectiveness of the authors' proposed approach, they have trained few classifiers with the groups extracted from a direct marketing campaign of a Portuguese banking institution and show that the classification accuracy is better compared to the results obtained in some previous work where the full dataset has been used to train the same classifiers.
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Srisarkun, V., and C. Jittawiriyanukoon. "An approximation of balanced score in neutrosophic graphs with weak edge weights." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 6 (2021): 5286. http://dx.doi.org/10.11591/ijece.v11i6.pp5286-5291.
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Neutrosophic concept is known undirected graph theory to involve with complex logistic networks, not clearly given and unpredictable real life situations, where fuzzy logic malfunctions to model. The transportation objective is to ship all logistic nodes in the network. The logistic network mostly experiences in stable condition, but for some edges found to be volatile. The weight of these erratic edges may vary at random (bridge-lifting/bascule, ad hoc accident on road, traffic condition) In this article, we propose an approximation algorithm for solving minimum spanning tree (MST) of an undirected neutrosophic graphs (UNG), in which the edge weights represent neutrosophic values. The approximation upon the balanced score calculation is introduced for all known configurations in alternative MST. As the result, we further compute decisive threshold value for the weak weights amid minimum cost pre-computation. If the threshold triggers then the proper MST can direct the decision and avoid post-computation. The proposed algorithm is also related to other existing approaches and a numerical analysis is presented.
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Bratkovskaya, Elena, Susanne Glässel, Viktar Kireyeu, et al. "Midrapidity cluster formation in heavy-ion collisions." EPJ Web of Conferences 276 (2023): 03005. http://dx.doi.org/10.1051/epjconf/202327603005.
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We study the production of clusters and hypernuclei at midrapidity employing the Parton-Hadron- Quantum-Molecular-Dynamics (PHQMD) approach, a microscopic n-body transport model based on the QMD propagation of the baryonic degrees of freedom with density dependent 2-body potential interactions. In PHQMD the cluster formation occurs dynamically, caused by the interactions. The clusters are recognized by the Minimum Spanning Tree (MST) algorithm. We present the PHQMD results for cluster and hypernuclei formation in comparison with the available experimental data at relativistic energies. PHQMD allows to study the time evolution of formed clusters and the origin of their production, which helps to understand how such weakly bound objects are formed and survive in the rather dense and hot environment created in heavy-ion collisions. It offers therefore an explanation of the ’ice in the fire’ puzzle. To investigate whether this explanation of the ’ice in the fire’ puzzle applies only to the MST results we study also the deuterons production by coalescence. We embed MST and coalescence in the PHQMD and UrQMD transport approaches in order to obtain model independent results. We find that both clustering procedures give very similar results for the deuteron observables in the UrQMD as well as in the PHQMD environment. This confirms that our solution for the ’ice in the fire’ puzzle is common to MST and coalescence and independent of the transport approach.
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Turan, Erhan, and Umut Orhan. "Confidence Indexing of Automated Detected Synsets: A Case Study on Contemporary Turkish Dictionary." ACM Transactions on Asian and Low-Resource Language Information Processing 21, no. 1 (2022): 1–19. http://dx.doi.org/10.1145/3469724.
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In this study, a novel confidence indexing algorithm is proposed to minimize human labor in controlling the reliability of automatically extracted synsets from a non-machine-readable monolingual dictionary. Contemporary Turkish Dictionary of Turkish Language Association is used as the monolingual dictionary data. First, the synonym relations are extracted by traditional text processing methods from dictionary definitions and a graph is prepared in Lemma-Sense network architecture. After each synonym relation is labeled by a proper confidence index, synonym pairs with desired confidence indexes are analyzed to detect synsets with a spanning tree-based method. This approach can label synsets with one of three cumulative confidence levels (CL-1, CL-2, and CL-3). According to the confidence levels, synsets are compared with KeNet which is the only open access Turkish Wordnet. Consequently, while most matches with the synsets of KeNet is determined in CL-1 and CL-2 confidence levels, the synsets determined at CL-3 level reveal errors in the dictionary definitions. This novel approach does not find only the reliability of automatically detected synsets, but it can also point out errors of detected synsets from the dictionary.
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Manger, Paul R., and Oxana Eschenko. "The Mammalian Locus Coeruleus Complex—Consistencies and Variances in Nuclear Organization." Brain Sciences 11, no. 11 (2021): 1486. http://dx.doi.org/10.3390/brainsci11111486.
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Descriptions of the nuclear parcellation of the locus coeruleus complex have been provided in approximately 80 mammal species spanning the phylogenetic breadth of this class. Within the mammalian rostral hindbrain, noradrenergic neurons (revealed with tyrosine hydroxylase and dopamine-ß-hydroxylase immunohistochemistry) have been observed within the periventricular grey matter (A4 and A6 nuclei) and parvicellular reticular nucleus (A5 and A7 nuclei), with the one exception to date being the tree pangolin, where no A4/A6 neurons are observed. The alphanumeric nomenclature system, developed in laboratory rodent brains, has been adapted to cover the variation observed across species. Cross-species homology is observed regarding the nuclear organization of noradrenergic neurons located in the parvicellular reticular nucleus (A5 and A7). In contrast, significant variations are observed in the organization of the A6 neurons of the locus coeruleus proper. In most mammals, the A6 is comprised of a moderate density of neurons, but in Murid rodents, primates, and megachiropteran bats, the A6 exhibits a very high density of neurons. In primates and megachiropterans, there is an additional moderate density of A6 neurons located rostromedial to the high-density portion. These variations are of importance in understanding the translation of findings in laboratory rodents to humans.
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Veličković, Boban. "Jensen's ⃞ principles and the Novák number of partially ordered sets." Journal of Symbolic Logic 51, no. 1 (1986): 47–58. http://dx.doi.org/10.2307/2273941.
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In this paper we consider various properties of Jensen's □ principles and use them to construct several examples concerning the so-called Novák number of partially ordered sets.In §1 we give the relevant definitions and review some facts about □ principles. Apart from some simple observations most of the results in this section are known.In §2 we consider the Novák number of partially ordered sets and, using □ principles, give counterexamples to the productivity of this cardinal function. We also formulate a principle, show by forcing that it is consistent and use it to construct an ℵ2-Suslin tree T such that forcing with T × T collapses ℵ1.In §3 we briefly consider games played on partially ordered sets and relate them to the problems of the previous section. Using a version of □ we give an example of a proper partial order such that the game of length ω played on is undetermined.In §4 we raise the question of whether the Novák number of a homogenous partial order can be singular, and show that in some cases the answer is no.We assume familiarity with the basic techniques of forcing. In §1 some facts about large cardinals (e.g. weakly compact cardinals are -indescribable) and elementary properties of the constructible hierarchy are used. For this and all undefined terms we refer the reader to Jech [10].
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Gray, S., S. Jackson, K. Taylor, C. Palmer, and C. Fastie. "Tree-Ring Based Reconstructions of Paleo-Precipitation Regimes in the Eastern Yellowstone Region." UW National Parks Service Research Station Annual Reports 24 (January 1, 2000): 144–48. http://dx.doi.org/10.13001/uwnpsrc.2000.3431.
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There are few other regions where the influence of climate on basic ecosystem attributes has been as well documented as the Greater Yellowstone Ecosystem (GYE). Research has shown that elk, bison, and grizzly bear populations in the GYE are tightly linked to annual climate variation (Meagher 1976, Picton 1978). Authors have shown that the distribution of vegetation types in Grand Teton and Yellowstone National Parks is influenced by the seasonality of precipitation (Despain 1987, 1990). Natural disturbances, especially fires and insect outbreaks, are also known to coincide with specific climate scenarios in this region (Knight 1987, Balling et al. 1992). Therefore, understanding how climate can vary over time is essential for the proper management of these areas (Luckman 1996). Modem instrumental records have contributed greatly to our understanding of the current GYE climate system. In particular, work by Mock (1996) and Bartlein et al. (1997) has demonstrated how local manifestations of large-scale circulation patterns produce distinct climates within the GYE. In addition, studies using modem climate records and General Circulation Models by Balling et al. (1992) and Bartlein et al. (1997) have identified trends toward increasing aridity in the GYE and the potential for these trends to continue well into the future. Late Pleistocene and Holocene (18-1 kya) climate in the GYE is known mainly from lakeÂsediment cores. Work by Whitlock (1993), Whitlock and Bartlein (1993), and Thompson et al. (1993) indicates that after deglaciation, increased solar radiation during summer months led to a highly seasonal climate regime. As levels of solar radiation changed through the Holocene, GYE climate became increasingly more like today until the modem regime became established around 1500-1600 AD (Whitlock 1993, Elias 1997). While existing modem and paleoecological studies reveal important aspects of the GYE climate system, there is a distinct lack of high-resolution data for most of the last millennium. Lake sediments only record climate variation at a resolution of hundreds to thousands of years, and instrumental records do not exist before the 1890s. Dendroclimatology, the study of climate using patterns of tree-ring growth (Fritts 1976) is particularly well suited to fill this gap in our knowledge of GYE climate. Tree-rings have been used successfully for climate reconstructions worldwide, offer records spanning decades to millennia, and can provide annual resolution. Therefore, we are developing a network of tree-ring sites in the western Absaroka Mountains and eastern Bighorn Basin to fill important spatial (areas east of Yellowstone NP) and temporal (high resolution for the past 700-1,000+year) gaps in our knowledge of GYE climate.
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Popovic, Tatjana, Aleksandra Jelusic, Petar Mitrovic, Renata Ilicic, and Sanja Markovic. "Allelic profile of Serbian Xanthomonas campestris pv. campestris isolates from cabbage." Pesticidi i fitomedicina 35, no. 1 (2020): 19–26. http://dx.doi.org/10.2298/pif2001019p.
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Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot disease of cabbage (Brassica oleracea var. capitata L.), is one of the most important bacteria which affect proper cabbage growth, leading to head weight and quality losses and thereby drastically reducing its marketing value. The pathogen is genetically diverse, which is evident from the presence of eleven races worldwide and more than thirty combinations of allelic profiles. Therefore, this study aimed to determine the allelic profiles of Serbian cabbage Xcc strains obtained in 2014. The analysis was done on three selected Xcc strains whose DNA was first amplified using polymerase chain reaction (PCR) with four housekeeping genes - P-XdnaK, fyuA, gyrB, and rpoD, then sequenced, and the obtained sequences were finally used to determine allelic profiles. Allelic profiles were determined by comparison with 33 Xcc strains obtained from different hosts and regions, whose allelic profiles had been determined previously. A non-redundant database (NRDB) from the pubMLST was used for allelic profile determination and Phyloviz software for constructing a minimum spanning tree. The obtained allelic profile of all Serbian Xcc cabbage strains was 1, 3, 1, 1 for the P-X-dnaK, fyuA, gyrB and rpoD genes, respectively. This profile is assigned as sequence type 2 (ST2) and it coincides with a Portuguese B. oleracea Xcc strain, CPBF 213, originating from B. oleracea var. costata. No connection between sequence type (ST) and the host was detected.
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Bhattacharya, Souradeep, Kaushar Vaidya, W. P. Chen, and Giacomo Beccari. "The blue straggler population of the old open cluster Berkeley 17." Astronomy & Astrophysics 624 (April 2019): A26. http://dx.doi.org/10.1051/0004-6361/201834449.
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Context. Blue straggler stars (BSSs) are observed in Galactic globular clusters and old open clusters. The radial distribution of BSSs has been used to diagnose the dynamical evolution of globular clusters. For the first time, with a reliable sample of BSSs identified with Gaia DR2, we conduct such an analysis for an open cluster. Aims. We aim to identify members, including BSSs, of the oldest known Galactic open cluster Berkeley 17 with the Gaia DR2 proper motions and parallaxes. We study the radial distribution of the BSS population to understand the dynamical evolution of the cluster. Methods. We selected cluster members to populate the colour magnitude diagram in the Gaia filters. Cluster parameters are derived using the brightest members. The BSSs and giant branch stars are identified, and their radial distributions are compared. The segregation of BSSs is also evaluated with respect to the giant branch stars using the minimum spanning tree (MST) analysis. Results. We determine Berkeley 17 to be at 3138.6−352.9+285.5 pc. We find 23 BSS cluster members, only two of which were previously identified. We find a bimodal radial distribution of BSSs supported by findings from the MST method. Conclusions. The bimodal radial distribution of BSSs in Berkeley 17 indicates that they have just started to sink towards the cluster centre, placing Berkeley 17 with globular clusters of intermediate dynamical age. This is the first such determination for an open cluster.
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Rezvanian, Alireza, and Mohammad Reza Meybodi. "Finding Maximum Clique in Stochastic Graphs Using Distributed Learning Automata." International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems 23, no. 01 (2015): 1–31. http://dx.doi.org/10.1142/s0218488515500014.
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Because of unpredictable, uncertain and time-varying nature of real networks it seems that stochastic graphs, in which weights associated to the edges are random variables, may be a better candidate as a graph model for real world networks. Once the graph model is chosen to be a stochastic graph, every feature of the graph such as path, clique, spanning tree and dominating set, to mention a few, should be treated as a stochastic feature. For example, choosing stochastic graph as the graph model of an online social network and defining community structure in terms of clique, and the associations among the individuals within the community as random variables, the concept of stochastic clique may be used to study community structure properties. In this paper maximum clique in stochastic graph is first defined and then several learning automata-based algorithms are proposed for solving maximum clique problem in stochastic graph where the probability distribution functions of the weights associated with the edges of the graph are unknown. It is shown that by a proper choice of the parameters of the proposed algorithms, one can make the probability of finding maximum clique in stochastic graph as close to unity as possible. Experimental results show that the proposed algorithms significantly reduce the number of samples needed to be taken from the edges of the stochastic graph as compared to the number of samples needed by standard sampling method at a given confidence level.
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Davis, Kara L., Erin F. Simonds, Sean C. Bendall, Wendy J. Fantl, and Garry P. Nolan. "Mass Cytometry Organizes the Heterogeneity of Pediatric B Cell Acute Lymphoblastic Leukemia." Blood 118, no. 21 (2011): 753. http://dx.doi.org/10.1182/blood.v118.21.753.753.
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Abstract Abstract 753 Pediatric B Cell Acute Lymphoblastic Leukemia: Common and Unique Differentiation States Defined by Signaling Response States Background: When mutations or regulatory dysfunction drive inappropriate cell division or survival this sets the stage for cancer initiation or progression. At what point do cells in an early cancer veer from their normal cellular routines to no longer participate in the development of a normal cellular tissue architecture & differentiation heirarchy? Do they still attempt to play out their programming to some degree, or are they “free actors”? The fact that cancers of any given type appear to remain tied to phenotypic classification schemes is illustrated in traditional clinical stratification systems. Paradoxically, cancers are considered (by some) as “heterogeneous”, whereas as a class they appear to recapitulate patterns of clinical responses, gene expression, signaling states. To what extent are these repeated molecular patterns mirrored at the level of differentiation? We mapped, at the single cell level, patterns of expression of markers and phenotypic traits that might be similar or unique across patient subgroups of pediatric B-cell ALL samples using 35 parameter proteomic mass cytometry. Using the features assignable to each single cell, with a statistical reconstruction of most likely similarity of features in 35 dimensional space, we mapped a “common” differentiation tree previously unrecognized by conventional analyses, and demonstrate here how differences in certain markers distinguish, or create, common phenotypic co-expression features across these ALL patients, or suggest patient-specific derailing of differentiation associated with changes in signaling module expression states. Methods: Cryopreserved cells were obtained from 8 pediatric B cell ALL patients under informed consent. 19 surface markers were used to cluster data into metacells of localized similarity displayed in a tree of local relationships via hierarchical cell lineage clustering and spanning-tree progression analysis of density-normalized events (SPADE) (Figure 1) (Bendall et al, Science 6 May2011; 332: 687–696). Results: The blast cell subpopulations comprised the areas of greatest density on the spanning trees–consistent with the fact that these cells are the most prevalent. Blast populations displayed variable expression of B cell precursor surface markers such as CD10, CD19, CD34 and CD38—even though clinical phenotyping placed all patients in a similar class. SPADE analysis detailed unexpected sub-branches prominently observed in certain patients, while absent or weakly represented in others. This confirms common signaling and differentiation states can be observed across patients, but individual patients can manifest unique and prevalent outgrowths of these common malignant differentiation states. Three patients' disease appears to gain a transformative event during a common point at a “pre-B cell development state, leading to local expansion at this halted population of characteristic immunophenotype. Sample ALL04 appears to have an outgrowth of cells with the earliest pre-B cell progenitors, whereas ALL01 is consistent with a maturing pre B cell, gaining expression of CD45. Notably, ALL03, characterized by an MLL rearrangement, clusters with myeloid cells and is CD10 negative, suggesting transformation prior to lymphocyte commitment. The cellular responses to perturbation provides added structure to the cellular subsets; responses to stimulation of the preB cell receptor are present within the majority of blast populations for ALL01 but absent in most for ALL03 and ALL04. We will present this and other findings related to these patients, as well as application of this approach to other tumor types. Conclusion:This high-dimensional immunophenotypic analysis of single cells from primary patient samples reveals an unseen developmental structure within pediatric B precursor acute lymphoblastic leukemia. The developmental stage at which the transformative event occurs informs the characteristic response to perturbation and critically, to drug treatment. *KD and ES contributed equally to this work. Disclosures: Fantl: Nodality, Inc.: Equity Ownership.
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Norwood, Zach. "The Combinatorics and Absoluteness of Definable Sets of Real Numbers." Bulletin of Symbolic Logic 28, no. 2 (2022): 263–64. http://dx.doi.org/10.1017/bsl.2021.55.
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AbstractThis thesis divides naturally into two parts, each concerned with the extent to which the theory of $L(\mathbf {R})$ can be changed by forcing.The first part focuses primarily on applying generic-absoluteness principles to how that definable sets of reals enjoy regularity properties. The work in Part I is joint with Itay Neeman and is adapted from our paper Happy and mad families in $L(\mathbf {R})$ , JSL, 2018. The project was motivated by questions about mad families, maximal families of infinite subsets of $\omega $ of which any two have only finitely many members in common. We begin, in the spirit of Mathias, by establishing (Theorem 2.8) a strong Ramsey property for sets of reals in the Solovay model, giving a new proof of Törnquist’s theorem that there are no infinite mad families in the Solovay model.In Chapter 3 we stray from the main line of inquiry to briefly study a game-theoretic characterization of filters with the Baire Property.Neeman and Zapletal showed, assuming roughly the existence of a proper class of Woodin cardinals, that the boldface theory of $L(\mathbf {R})$ cannot be changed by proper forcing. They call their result the Embedding Theorem, because they conclude that in fact there is an elementary embedding from the $L(\mathbf {R})$ of the ground model to that of the proper forcing extension. With a view toward analyzing mad families under $\mathsf {AD}^+$ and in $L(\mathbf {R})$ under large-cardinal hypotheses, in Chapter 4 we establish triangular versions of the Embedding Theorem. These are enough for us to use Mathias’s methods to show (Theorem 4.5) that there are no infinite mad families in $L(\mathbf {R})$ under large cardinals and (Theorem 4.9) that $\mathsf {AD}^+$ implies that there are no infinite mad families. These are again corollaries of theorems about strong Ramsey properties under large-cardinal assumptions and $\mathsf {AD}^+$ , respectively. Our first theorem improves the large-cardinal assumption under which Todorcevic established the nonexistence of infinite mad families in $L(\mathbf {R})$ . Part I concludes with Chapter 5, a short list of open questions.In the second part of the thesis, we undertake a finer analysis of the Embedding Theorem and its consistency strength. Schindler found that the the Embedding Theorem is consistent relative to much weaker assumptions than the existence of Woodin cardinals. He defined remarkable cardinals, which can exist even in L, and showed that the Embedding Theorem is equiconsistent with the existence of a remarkable cardinal. His theorem resembles a theorem of Harrington–Shelah and Kunen from the 1980s: the absoluteness of the theory of $L(\mathbf {R})$ to ccc forcing extensions is equiconsistent with a weakly compact cardinal. Joint with Itay Neeman, we improve Schindler’s theorem by showing that absoluteness for $\sigma $ -closed $\ast $ ccc posets—instead of the larger class of proper posets—implies the remarkability of $\aleph _1^V$ in L. This requires a fundamental change in the proof, since Schindler’s lower-bound argument uses Jensen’s reshaping forcing, which, though proper, need not be $\sigma $ -closed $\ast $ ccc in that context. Our proof bears more resemblance to that of Harrington–Shelah than to Schindler’s.The proof of Theorem 6.2 splits naturally into two arguments. In Chapter 7 we extend the Harrington–Shelah method of coding reals into a specializing function to allow for trees with uncountable levels that may not belong to L. This culminates in Theorem 7.4, which asserts that if there are $X\subseteq \omega _1$ and a tree $T\subseteq \omega _1$ of height $\omega _1$ such that X is codable along T (see Definition 7.3), then $L(\mathbf {R})$ -absoluteness for ccc posets must fail.We complete the argument in Chapter 8, where we show that if in any $\sigma $ -closed extension of V there is no $X\subseteq \omega _1$ codable along a tree T, then $\aleph _1^V$ must be remarkable in L.In Chapter 9 we review Schindler’s proof of generic absoluteness from a remarkable cardinal to show that the argument gives a level-by-level upper bound: a strongly $\lambda ^+$ -remarkable cardinal is enough to get $L(\mathbf {R})$ -absoluteness for $\lambda $ -linked proper posets.Chapter 10 is devoted to partially reversing the level-by-level upper bound of Chapter 9. Adapting the methods of Neeman, Hierarchies of forcing axioms II, we are able to show that $L(\mathbf {R})$ -absoluteness for $\left |\mathbf {R}\right |\cdot \left |\lambda \right |$ -linked posets implies that the interval $[\aleph _1^V,\lambda ]$ is $\Sigma ^2_1$ -remarkable in L.Abstract prepared by Zach Norwood.E-mail: zachnorwood@gmail.com
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Kazllarof, Vangjel, Stamatis Karlos, and Sotiris Kotsiantis. "Investigation of Combining Logitboost(M5P) under Active Learning Classification Tasks." Informatics 7, no. 4 (2020): 50. http://dx.doi.org/10.3390/informatics7040050.
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Active learning is the category of partially supervised algorithms that is differentiated by its strategy to combine both the predictive ability of a base learner and the human knowledge so as to exploit adequately the existence of unlabeled data. Its ambition is to compose powerful learning algorithms which otherwise would be based only on insufficient labelled samples. Since the latter kind of information could raise important monetization costs and time obstacles, the human contribution should be seriously restricted compared with the former. For this reason, we investigate the use of the Logitboost wrapper classifier, a popular variant of ensemble algorithms which adopts the technique of boosting along with a regression base learner based on Model trees into 3 different active learning query strategies. We study its efficiency against 10 separate learners under a well-described active learning framework over 91 datasets which have been split to binary and multi-class problems. We also included one typical Logitboost variant with a separate internal regressor for discriminating the benefits of adopting a more accurate regression tree than one-node trees, while we examined the efficacy of one hyperparameter of the proposed algorithm. Since the application of the boosting technique may provide overall less biased predictions, we assume that the proposed algorithm, named as Logitboost(M5P), could provide both accurate and robust decisions under active learning scenarios that would be beneficial on real-life weakly supervised classification tasks. Its smoother weighting stage over the misclassified cases during training as well as the accurate behavior of M5P are the main factors that lead towards this performance. Proper statistical comparisons over the metric of classification accuracy verify our assumptions, while adoption of M5P instead of weak decision trees was proven to be more competitive for the majority of the examined problems. We present our results through appropriate summarization approaches and explanatory visualizations, commenting our results per case.
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Roth, R., and F. Joos. "A reconstruction of radiocarbon production and total solar irradiance from the Holocene <sup>14</sup>C and CO<sub>2</sub> records: implications of data and model uncertainties." Climate of the Past Discussions 9, no. 2 (2013): 1165–235. http://dx.doi.org/10.5194/cpd-9-1165-2013.
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Abstract. Past atmospheric CO2 concentrations reconstructed from polar ice cores combined with its Δ14C signature as conserved in tree-rings provide important information both on the cycling of carbon as well as the production of radiocarbon (Q) in the atmosphere. The latter is modulated by changes in the strength of the magnetic field enclosed in the solar wind and is a proxy for past changes in solar activity. We perform transient carbon-cycle simulations spanning the past 21 kyr using Bern3D-LPX, a fully featured Earth System Model of Intermediate Complexity (EMIC) with a 3-D ocean, sediment and a dynamic vegetation model. Using the latest atmospheric IntCal09/SHCal04 radiocarbon records, we reconstruct the Holocene radiocarbon fluxes and the total production rate. Our carbon-cycle based modern estimate of Q ≈ 1.7 atoms cm−2 s−1 is lower than previously reported by Masarik and Beer (2009) and more in line with Kovaltsov et al. (2012). Q is then translated into the solar modulation potential (Φ) using the latest geomagnetic field reconstruction and linked to a recent reanalysis of early instrumental data. In contrast to earlier reconstructions, our record suggests that periods of high solar activity (>600 MeV) were quite common not only in recent millennia but throughout the Holocene. Solar activity in our decadally-smoothed record is during 28% of the time higher than the modern average of 650 MeV during the past 9 ka. But due to considerable uncertainties in the normalization of Φ to instrumental data, the absolute value of Φ remains weakly constrained. Further, our simulations with a spatially resolved model (taking the interhemispheric Δ14C gradient into account) show that reconstructions that rely on the Northern Hemisphere 14C record only are biased towards low values during the Holocene. Notable deviations on decadal-to-centennial time scales are also found in comparison with earlier reconstructions. In a last step, past total solar irradiance (TSI) is quantified using a recently published Φ-TSI relationship yielding small changes in Holocene TSI of order 1 W m−2 with a Maunder Minimum irradiance reduction of 0.85 ± 0.17 W m−2. Future extension of TSI using autoregressive modeling suggest a declining solar activity in the next decades towards average Holocene conditions. Past TSI changes are finally translated into changes in surfaces atmospheric temperature (SAT) by forcing the Bern3D-LPX model with our new TSI record, yielding SAT anomalies of less than 0.1 K.
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Bakker, Freek T., Alexandre Antonelli, Julia A. Clarke, et al. "The Global Museum: natural history collections and the future of evolutionary science and public education." PeerJ 8 (January 28, 2020): e8225. http://dx.doi.org/10.7717/peerj.8225.
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Natural history museums are unique spaces for interdisciplinary research and educational innovation. Through extensive exhibits and public programming and by hosting rich communities of amateurs, students, and researchers at all stages of their careers, they can provide a place-based window to focus on integration of science and discovery, as well as a locus for community engagement. At the same time, like a synthesis radio telescope, when joined together through emerging digital resources, the global community of museums (the ‘Global Museum’) is more than the sum of its parts, allowing insights and answers to diverse biological, environmental, and societal questions at the global scale, across eons of time, and spanning vast diversity across the Tree of Life. We argue that, whereas natural history collections and museums began with a focus on describing the diversity and peculiarities of species on Earth, they are now increasingly leveraged in new ways that significantly expand their impact and relevance. These new directions include the possibility to ask new, often interdisciplinary questions in basic and applied science, such as in biomimetic design, and by contributing to solutions to climate change, global health and food security challenges. As institutions, they have long been incubators for cutting-edge research in biology while simultaneously providing core infrastructure for research on present and future societal needs. Here we explore how the intersection between pressing issues in environmental and human health and rapid technological innovation have reinforced the relevance of museum collections. We do this by providing examples as food for thought for both the broader academic community and museum scientists on the evolving role of museums. We also identify challenges to the realization of the full potential of natural history collections and the Global Museum to science and society and discuss the critical need to grow these collections. We then focus on mapping and modelling of museum data (including place-based approaches and discovery), and explore the main projects, platforms and databases enabling this growth. Finally, we aim to improve relevant protocols for the long-term storage of specimens and tissues, ensuring proper connection with tomorrow’s technologies and hence further increasing the relevance of natural history museums.
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Odyuo, Yanrenthung, Dipu Sarkar, and Lilika Sumi. "Optimal feeder reconfiguration in distributed generation environment under time-varying loading condition." SN Applied Sciences 3, no. 6 (2021). http://dx.doi.org/10.1007/s42452-021-04557-w.
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Abstract The development and planning of optimal network reconfiguration strategies for electrical networks is greatly improved with proper application of graph theory techniques. This paper investigates the application of Kruskal's maximal spanning tree algorithm in finding the optimal radial networks for different loading scenarios from an interconnected meshed electrical network integrated with distributed generation (DG). The work is done with an objective to assess the prowess of Kruskal's algorithm to compute, obtain or derive an optimal radial network (optimal maximal spanning tree) that gives improved voltage stability and highest loss minimization from among all the possible radial networks obtainable from the DG-integrated mesh network for different time-varying loading scenarios. The proposed technique has been demonstrated on a multiple test systems considering time-varying load levels to investigate the performance and effectiveness of the suggested method. For interconnected electrical networks with the presence of distributed generation, it was found that application of Kruskal's algorithm quickly computes optimal radial configurations that gives the least amount of power losses and better voltage stability even under varying load conditions. Article Highlights Investigated network reconfiguration strategies for electrical networks with the presence of Distributed Generation for time-varying loading conditions. Investigated the application of graph theory techniques in electrical networks for developing and planning reconfiguration strategies. Applied Kruskal’s maximal spanning tree algorithm to obtain the optimal radial electrical networks for different loading scenarios from DG-integrated meshed electrical network.
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Ruelle, Philippe. "Sandpile Models in the Large." Frontiers in Physics 9 (June 2, 2021). http://dx.doi.org/10.3389/fphy.2021.641966.
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This contribution is a review of the deep and powerful connection between the large-scale properties of critical systems and their description in terms of a field theory. Although largely applicable to many other models, the details of this connection are illustrated in the class of two-dimensional Abelian sandpile models. Bulk and boundary height variables, spanning tree–related observables, boundary conditions, and dissipation are all discussed in this context and found to have a proper match in the field theoretic description.
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Aprile, Manuel, Samuel Fiorini, Tony Huynh, Gwenaël Joret, and David R. Wood. "Smaller Extended Formulations for Spanning Tree Polytopes in Minor-closed Classes and Beyond." Electronic Journal of Combinatorics 28, no. 4 (2021). http://dx.doi.org/10.37236/10522.
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Let $G$ be a connected $n$-vertex graph in a proper minor-closed class $\mathcal G$. We prove that the extension complexity of the spanning tree polytope of $G$ is $O(n^{3/2})$. This improves on the $O(n^2)$ bounds following from the work of Wong (1980) and Martin (1991). It also extends a result of Fiorini, Huynh, Joret, and Pashkovich (2017), who obtained a $O(n^{3/2})$ bound for graphs embedded in a fixed surface. Our proof works more generally for all graph classes admitting strongly sublinear balanced separators: We prove that for every constant $\beta$ with $0<\beta<1$, if $\mathcal G$ is a graph class closed under induced subgraphs such that all $n$-vertex graphs in $\mathcal G$ have balanced separators of size $O(n^\beta)$, then the extension complexity of the spanning tree polytope of every connected $n$-vertex graph in $\mathcal{G}$ is $O(n^{1+\beta})$. We in fact give two proofs of this result, one is a direct construction of the extended formulation, the other is via communication protocols. Using the latter approach we also give a short proof of the $O(n)$ bound for planar graphs due to Williams (2002).
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Huang, Guan, Zhuo Zhang, Weisheng Yan, and Xinxin Guo. "Differential graphical games of multiagent systems with nonzero leader's control input and external disturbances." International Journal of Robust and Nonlinear Control, April 18, 2024. http://dx.doi.org/10.1002/rnc.7378.
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AbstractIn this article, we investigate the problem of differential graphical games for multiagent systems (MASs) with external disturbances. In particular, the system considered in this article allows the leader to have an unknown bounded control input, and the communication topology between agents is allowed to be a weakly restricted structure with only containing a directed spanning tree. We propose a novel dynamic sliding mode control strategy to dispose the presence of leader's nonzero control input and external disturbances. Furthermore, a nominal controller based on the worst‐case control strategies of neighbors is designed to provide a distributed solution for differential graphics games of MASs. Finally, our algorithms are applied to solve multiple unmanned surface vessels games. Simulation studies are provided to test the effectiveness of the proposed algorithms.
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Tian, Hongxiang, Enze Gong, Chongsi Xie, and Yi-Jian Du. "Evaluating EYM amplitudes in four dimensions by refined graphic expansion." Journal of High Energy Physics 2021, no. 4 (2021). http://dx.doi.org/10.1007/jhep04(2021)150.
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Abstract The recursive expansion of tree level multitrace Einstein-Yang-Mills (EYM) amplitudes induces a refined graphic expansion, by which any tree-level EYM amplitude can be expressed as a summation over all possible refined graphs. Each graph contributes a unique coefficient as well as a proper combination of color-ordered Yang-Mills (YM) amplitudes. This expansion allows one to evaluate EYM amplitudes through YM amplitudes, the latter have much simpler structures in four dimensions than the former. In this paper, we classify the refined graphs for the expansion of EYM amplitudes into N k MHV sectors. Amplitudes in four dimensions, which involve k + 2 negative-helicity particles, at most get non-vanishing contribution from graphs in N k′ (k′ ≤ k) MHV sectors. By the help of this classification, we evaluate the non-vanishing amplitudes with two negative-helicity particles in four dimensions. We establish a correspondence between the refined graphs for single-trace amplitudes with $$ \left({g}_i^{-},{g}_j^{-}\right) $$ g i − g j − or $$ \left({h}_i^{-},{g}_j^{-}\right) $$ h i − g j − configuration and the spanning forests of the known Hodges determinant form. Inspired by this correspondence, we further propose a symmetric formula of double-trace amplitudes with $$ \left({g}_i^{-},{g}_j^{-}\right) $$ g i − g j − configuration. By analyzing the cancellation between refined graphs in four dimensions, we prove that any other tree amplitude with two negative-helicity particles has to vanish.
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Zhang, Haixiang, Chong Chen, Jun Huang, and Yueyuan Zhang. "Consensus based on output for nonlinear multi-agent systems with switching topologies." Transactions of the Institute of Measurement and Control, May 12, 2022, 014233122210966. http://dx.doi.org/10.1177/01423312221096683.
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This article addresses the consensus problem based on static output feedback for a kind of leader-following multi-agent systems. Traditional nonlinear constraints, such as Lipschitz and one-sided Lipschitz, cannot describe most nonlinear functions. The incremental quadratic constraints and switching topologies are considered to extend the application range and practical significance of the existing consensus control protocol. By investigating the topology having a directed spanning tree and constructing a proper Lyapunov function, this article gives sufficient conditions for the consensus problem, including the dwell time by a threshold value. Then, a design method for the static output feedback gain matrix is deduced and an algorithm for achieving consensus is presented. Finally, two simulation examples are used to verify the validity as well as the superiority of the designed protocol. It is the first piece of work to study the consensus problem of multi-agent with incremental quadratic constraints under switching topologies.
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Zhang, Yunlong, Guoguang Wen, Ahmed Rahmani, Zhaoxia Peng, and Wei Hu. "Cluster consensus of multi-agent systems with general linear and nonlinear dynamics via intermittent adaptive pinning control." Transactions of the Institute of Measurement and Control, December 14, 2020, 014233122097525. http://dx.doi.org/10.1177/0142331220975254.
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This paper investigates the cluster consensus of multi-agent systems (MASs) with general linear and nonlinear dynamics via intermittent adaptive pinning control, where each cluster has a virtual leader whose state can be sensed by only a small part of followers on some disconnected time intervals because of communication constraints. The communication topology is considered to be weakly connected, that is, it is not necessary to be in-degree balanced, strongly connected or contain a directed spanning tree. To realise the cluster consensus, a class of intermittent adaptive pinning control protocols is proposed according to difference that the agents receive information source. The pinning gains are designed to be intermittent adaptive and with an exponential convergence rate, which will effectively reduce communication costs, avoid the pinning gains being larger than those needed in practice. Meanwhile, it guarantees that the pinning gains quickly converge to steady value. Correspondingly, some sufficient consensus criteria are derived to guarantee that the agents in the same cluster asymptotically can reach consensus while the agents in different clusters can reach different consensus. Rigorous proofs are given by the aid of Lyapunov stability theory and matrix theory. Finally, a numerical simulation example is presented to validate the main results.
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Edge, David C., Alan D. Wanamaker, Lydia M. Staisch, David J. Reynolds, Karine L. Holmes, and Bryan A. Black. "A MODERN MULTICENTENNIAL RECORD OF RADIOCARBON VARIABILITY FROM AN EXACTLY DATED BIVALVE CHRONOLOGY AT THE TREE NOB SITE (ALASKA COASTAL CURRENT)." Radiocarbon, November 10, 2022, 1–16. http://dx.doi.org/10.1017/rdc.2022.83.
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ABSTRACT Quantifying the marine radiocarbon reservoir effect, offsets (ΔR), and ΔR variability over time is critical to improving dating estimates of marine samples while also providing a proxy of water mass dynamics. In the northeastern Pacific, where no high-resolution time series of ΔR has yet been established, we sampled radiocarbon (14C) from exactly dated growth increments in a multicentennial chronology of the long-lived bivalve, Pacific geoduck (Paneopea generosa) at the Tree Nob site, coastal British Columbia, Canada. Samples were taken at approximately decadal time intervals from 1725 CE to 1920 CE and indicate average ΔR values of 256 ± 22 years (1σ) consistent with existing discrete estimates. Temporal variability in ΔR is small relative to analogous Atlantic records except for an unusually old-water event, 1802–1812. The correlation between ΔR and sea surface temperature (SST) reconstructed from geoduck increment width is weakly significant (r2 = .29, p = .03), indicating warm water is generally old, when the 1802–1812 interval is excluded. This interval contains the oldest (–2.1σ) anomaly, and that is coincident with the coldest (–2.7σ) anomalies of the temperature reconstruction. An additional 32 14C values spanning 1952–1980 were detrended using a northeastern Pacific bomb pulse curve. Significant positive correlations were identified between the detrended 14C data and annual El Niño Southern Oscillation (ENSO) and summer SST such that cooler conditions are associated with older water. Thus, 14C is generally relatively stable with weak, potentially inconsistent associations to climate variables, but capable of infrequent excursions as illustrated by the unusually cold, old-water 1802–1812 interval.
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Chen, Jun, Haoxin Lv, Zhixia Zhang, et al. "Multilocus Sequence Typing of Leuconostoc mesenteroides Strains From the Qinghai-Tibet Plateau." Frontiers in Microbiology 12 (January 25, 2021). http://dx.doi.org/10.3389/fmicb.2021.614286.
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Leuconostoc mesenteroides strains were a type of epiphytic bacterium widely used in fermented foods and products in the biochemical and pharmaceutical industries but data on its presence in foods from Qinghai-Tibet Plateau in China was scarce. In this study, molecular analysis based on multilocus sequence typing (MLST) with eight housekeeping genes (pyrG, groeL, rpoB, recA, uvrC, murC, carB, and pheS) was carried out on 45 L. mesenteroides strains isolated from different plants and dairy products from Qinghai-Tibet Plateau in China. The objective of this study was to perform genetic diversity analysis and explore the relationship between strains and isolate samples or separate regions. A total of 25 sequence types (STs) were identified with a diversity of up to 55.6%, which were grouped into one clonal complexes (CCs), 3 doublets and 17 singletons by eBURST. The results of minimum spanning tree and clustering analysis indicated these L. mesenteroides strains from the Qinghai-Tibet Plateau were relatively weakly related to the isolated region. However, there was a close relationship between the genotypes of L. mesenteroides strains and the type of the isolated sample, which was consistent with the results of API 50CH. The MLST scheme presented in this study provides a shareable and comparable sequence database and enhances our knowledge of the population diversity of L. mesenteroides strains which will be further used for the selection of industrial strains.
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Song, Wen-Yu, Kenneth Otieno Onditi, Xue-You Li, et al. "Decomposing niche components reveals simultaneous effects of opposite deterministic processes structuring alpine small mammal assembly." Frontiers in Ecology and Evolution 10 (January 4, 2023). http://dx.doi.org/10.3389/fevo.2022.999573.
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IntroductionSpecies distribution in alpine areas is constrained by multiple abiotic and biotic stressors. This leads to discrepant assembly patterns between different locations and study objects as opposite niche-based processes—limiting similarity and habitat filtering—simultaneously structure communities, masking overall patterns. We aimed to address how these processes structure small mammal communities in the alpine tree line transition zone, one of the most distinct vegetation transitions between alpine and montane habitats.MethodsWe compiled a dataset of species checklist, phylogeny, and functional traits from field collection and published sources spanning 18 mountains in southwest China. We first examined hypothetical niche-based processes with frequently used phylogenetic and trait approaches using this dataset. The species traits were decomposed into different niche components to explore the respective effects of specific stressors. Indices representing evolutionary history, trait space, and pairwise species distance were estimated and compared with null model expectations. Linear mixed-effect models were used to assess the association patterns between diversity indices and elevation.ResultsThe results indicated that phylogenetic and functional richness were positively correlated with species richness. In contrast, distance-based indices were either negatively or weakly positively correlated with species richness. Null model analyses suggested no evidence of non-random phylogenetic or overall trait patterns. However, the resource acquisition niche tended to be more overdispersed (positive slopes), while the habitat affinity niche tended to be more clustered (negative slopes) beyond the high elevation tree line.DiscussionThese findings show that opposite niche-based processes simultaneously structure small mammal communities in alpine areas. Overall, the present study provides vital insights into the complexity of assembly processes in these habitats. It also highlights the importance of relating relevant traits to distinguish the influences of specific abiotic and biotic stressors.
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Andriichuk, Oleh, Sergii Kadenko, and Vitaliy Tsyganok. "Significance of the order of pair‐wise comparisons in Analytic Hierarchy Process: an experimental study." Journal of Multi-Criteria Decision Analysis 31, no. 3-4 (2024). http://dx.doi.org/10.1002/mcda.1830.
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AbstractThe article describes an approach, ensuring higher credibility of expert estimation results, based on specific order of pair‐wise comparisons. The order of pair‐wise comparisons is, in its turn, based on the distance between estimated objects in the ranking. According to the suggested approach (and some human psychophysiological features), the most ordinally distant objects should be compared before ordinally closer ones. In order to empirically confirm this assumption, a special experiment involving real experts has been conducted. The results of the experiment indicate that if objects are presented to the expert for comparison in the suggested order, then in the majority of cases relative weights of objects, obtained using eigenvector method, most adequately reflect this expert's priorities. Moreover, pair‐wise comparison matrices constructed using the suggested comparison order tend to be slightly more consistent. The suggested approach to re‐ordering of pair‐wise comparisons can be applied as part of the AHP algorithm in weakly structured subject domains, influenced by multiple intangible criteria. It also provides conceptual basis for reduction of the number of pair‐wise comparisons, required to obtain credible results, in AHP without loss or distortion of expert data. It can also be used for modification of combinatorial pair‐wise comparison aggregation method, based on spanning tree enumeration. And, finally, it will improve the overall multi‐criteria decision‐making process in diverse subject domains, characterized by high uncertainty levels.
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Asadzadeh, Mohammad, Suhail Ahmad, Noura Al-Sweih, and Ziauddin Khan. "Molecular fingerprinting by multi-locus sequence typing identifies microevolution and nosocomial transmission of Candida glabrata in Kuwait." Frontiers in Public Health 11 (September 8, 2023). http://dx.doi.org/10.3389/fpubh.2023.1242622.
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BackgroundsCandida glabrata is a frequently isolated non-albicans Candida species and invasive C. glabrata infections in older patients are associated with high mortality rates. Opportunistic Candida infections in critically ill patients may be either endogenous or nosocomial in origin and this distinction is critical for effective intervention strategies. This study performed multi-locus sequence typing (MLST) to study genotypic relatedness among clinical C. glabrata isolates in Kuwait.MethodsCandida glabrata isolates (n = 91) cultured from 91 patients were analyzed by MLST. Repeat isolates (n = 16) from 9 patients were also used. Antifungal susceptibility testing for fluconazole, voriconazole, caspofungin and amphotericin B (AMB) was determined by Etest. Genetic relatedness was determined by constructing phylogenetic tree and minimum spanning tree by using BioNumerics software.ResultsResistance to fluconazole, voriconazole and AMB was detected in 7, 2 and 10 C. glabrata isolates, respectively. MLST identified 28 sequence types (STs), including 12 new STs. ST46 (n = 33), ST3 (n = 8), ST7 (n = 6) and ST55 (n = 6) were prevalent in ≥4 hospitals. Repeat isolates obtained from same or different site yielded identical ST. No association of ST46 with source of isolation or resistance to antifungals was apparent. Microevolution and cross-transmission of infection was indicated in two hospitals that yielded majority (57 of 91, 67%) of C. glabrata.ConclusionOur data suggest that C. glabrata undergoes microevolution in hospital environment and can be nosocomially transmitted to other susceptible patients. Thus, proper infection control practices during routine procedures on C. glabrata-infected patients may prevent transmission of this pathogen to other hospitalized patients.
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Mercer, Catherine, Vanessa M. Comeau, Lori D. Daniels, and Marco Carrer. "Contrasting Impacts of Climate Warming on Coastal Old-Growth Tree Species Reveal an Early Warning of Forest Decline." Frontiers in Forests and Global Change 4 (January 25, 2022). http://dx.doi.org/10.3389/ffgc.2021.775301.
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Old-growth forests in the Pacific Northwest are being fundamentally altered by climate change. A primary example of this is yellow-cedar (Callitropsis nootkatensis), a culturally and economically important species, which has suffered widespread decline across its range since the beginning of the twentieth century. We used tree rings to compare the climate-growth response of yellow-cedar to two co-occurring species; western hemlock (Tsuga heterophylla) and Sitka spruce (Picea sitchensis), in an old-growth forest on Haida Gwaii, Canada, to better understand the unique climatic drivers of a species that is declining across its range. We developed three species-specific chronologies spanning 560–770 years, reconstructing a long-term record of species growth and dynamics over time. The climate is strongly influenced by the Pacific Decadal Oscillation (PDO), a multi-decadal pattern of ocean-atmospheric climate variability. Climate varied across three time periods that have coincided with major shifts in the PDO during the twentieth century [1901–1945 (neutral/positive), 1946–1976 (negative) and 1977–2015 (positive)]. Conditions were significantly warmer and wetter during positive phases, with the greatest maximum temperatures in the most recent period. We used complimentary methods of comparison, including Morlet wavelet analysis, Pearson correlations, and linear-mixed effects modeling to investigate the relations between climate and species growth. All three species exhibited multi-decadal frequency variation, strongest for yellow-cedar, suggesting the influence of the PDO. Consistent with this, the strength and direction of climate-growth correlations varied among PDO phases. Growing season temperature in the year of ring formation was strongly positively correlated to yellow-cedar and western hemlock growth, most significantly in the latter two time periods, representing a release from a temperature limitation. Sitka spruce growth was only weakly associated with climate. Yellow-cedar responded negatively to winter temperature from 1977 to 2015, consistent with the decline mechanism. Increased yellow-cedar mortality has been linked to warmer winters and snow loss. This study provides new insights into yellow-cedar decline, finding the first evidence of decline-related growth patterns in an apparently healthy, productive coastal temperate rainforest.
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Götte, Thorsten, Kristian Hinnenthal, Christian Scheideler, and Julian Werthmann. "Time-optimal construction of overlay networks." Distributed Computing, February 15, 2023. http://dx.doi.org/10.1007/s00446-023-00442-4.
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AbstractThis article shows how to construct an overlay network of constant degree and diameter $$O(\log n)$$ O ( log n ) in $$O(\log n)$$ O ( log n ) time starting from an arbitrary weakly connected graph. We assume a synchronous communication network in which nodes can send messages to nodes they know the identifier of, and new connections can be established by sending node identifiers. Suppose the initial network’s graph is weakly connected and has constant degree. In that case, our algorithm constructs the desired topology with each node sending and receiving only $$O(\log n)$$ O ( log n ) messages in each round in $$O(\log n)$$ O ( log n ) time w.h.p., which beats the currently best $$O(\log ^{3/2} n)$$ O ( log 3 / 2 n ) time algorithm of Götte et al. (International colloquium on structural information and communication complexity (SIROCCO), Springer, 2019). Since the problem cannot be solved faster than by using pointer jumping for $$O(\log n)$$ O ( log n ) rounds (which would even require each node to communicate $$\Omega (n)$$ Ω ( n ) bits), our algorithm is asymptotically optimal. We achieve this speedup by using short random walks to repeatedly establish random connections between the nodes that quickly reduce the conductance of the graph using an observation of Kwok and Lau (Approximation, randomization, and combinatorial optimization. Algorithms and techniques (APPROX/RANDOM 2014), Schloss Dagstuhl-Leibniz-Zentrum fuer Informatik, 2014). Additionally, we show how our algorithm can be used to efficiently solve graph problems in hybrid networks (Augustine et al. in Proceedings of the fourteenth annual ACM-SIAM symposium on discrete algorithms, SIAM, 2020). Motivated by the idea that nodes possess two different modes of communication, we assume that communication of the initial edges is unrestricted, whereas only polylogarithmically many messages can be sent over edges that have been established throughout an algorithm’s execution. For an (undirected) graph G with arbitrary degree, we show how to compute connected components, a spanning tree, and biconnected components in $$O(\log n)$$ O ( log n ) time w.h.p. Furthermore, we show how to compute an MIS in $$O(\log d + \log \log n)$$ O ( log d + log log n ) time w.h.p., where d is the initial degree of G.
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Nawaz, Muhammad Saqib, Razia Asghar, Nashaiman Pervaiz, et al. "Molecular evolutionary and structural analysis of human UCHL1 gene demonstrates the relevant role of intragenic epistasis in Parkinson’s disease and other neurological disorders." BMC Evolutionary Biology 20, no. 1 (2020). http://dx.doi.org/10.1186/s12862-020-01684-7.
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Abstract Background Parkinson’s disease (PD) is the second most common neurodegenerative disorder. PD associated human UCHL1 (Ubiquitin C-terminal hydrolase L1) gene belongs to the family of deubiquitinases and is known to be highly expressed in neurons (1–2% in soluble form). Several functions of UCHL1 have been proposed including ubiquitin hydrolyze activity, ubiquitin ligase activity and stabilization of the mono-ubiquitin. Mutations in human UCHL1 gene have been associated with PD and other neurodegenerative disorders. The present study aims to decipher the sequence evolutionary pattern and structural dynamics of UCHL1. Furthermore, structural and interactional analysis of UCHL1 was performed to help elucidate the pathogenesis of PD. Results The phylogenetic tree topology suggests that the UCHL1 gene had originated in early gnathostome evolutionary history. Evolutionary rate analysis of orthologous sequences reveals strong purifying selection on UCHL1. Comparative structural analysis of UCHL1 pinpoints an important protein segment spanning amino acid residues 32 to 39 within secretion site with crucial implications in evolution and PD pathogenesis through a well known phenomenon called intragenic epistasis. Identified critical protein segment appears to play an indispensable role in protein stability, proper protein conformation as well as harboring critical interaction sites. Conclusions Conclusively, the critical protein segment of UCHL1 identified in the present study not only demonstrates the relevant role of intraprotein conformational epistasis in the pathophysiology of PD but also offers a novel therapeutic target for the disease.