Communicability Angles Reveal Critical Edges for Network Consensus Dynamics

We consider the question of determining how the topological structure influences a consensus dynamical process taking place on a network. By considering a large dataset of real-world networks we first determine that the removal of edges according to their communicability angle -an angle between position vectors of the nodes in an Euclidean communicability space- increases the average time of consensus by a factor of 5.68 in real-world networks. The edge betweenness centrality also identifies -in a smaller proportion- those critical edges for the consensus dynamics, i.e., its removal increases the time of consensus by a factor of 3.70. We justify theoretically these findings on the basis of the role played by the algebraic connectivity and the isoperimetric number of networks on the dynamical process studied, and their connections with the properties mentioned before. Finally, we study the role played by global topological parameters of networks on the consensus dynamics. We determine that the network density and the average distance-sum -an analogous of the node degree for shortest-path distances, account for more than 80% of the variance of the average time of consensus in the real-world networks studied.Comment: 15 pages, 2 figure

The Phytotoxic Potential of the Flowering Foliage of Gorse (Ulex europaeus) and Scotch Broom (Cytisus scoparius), as Pre-Emergent Weed Control in Maize in a Glasshouse Pot Experiment

In our previous studies, the phytotoxicity of Ulex europaeus (gorse) and Cytisus scoparius (Scotch broom) was demonstrated in vitro and argued to be caused by the release of volatile and water-soluble compounds from fresh plant foliage. In light of these positive results, there was a need to test the effects ex vitro. In this work, gorse and Scotch broom were used as soil amendments in pot experiments in a glasshouse by incorporating slashed plant material into the soil at a ratio of 1% w/w on a dry mass basis. The phytotoxic effects on the emergence and early growth of maize and five accompanying weed species were analyzed, as were the effect on soil fertility and soil community-level physiological profiles. Thirty days after incorporation, significant decreases in weed density of 32.2% and 59.5% were found for gorse and Scotch broom soil amendments, respectively. Gorse soil amendment was notably effective impairing the establishment of Amaranthus retroflexus and diminishing the plant height of Digitaria sanguinalis and Portulaca oleracea. Scotch broom soil amendment was capable of significantly inhibiting the emergence of D. sanguinalis, Convolvulus arvensis, P. oleracea, and A. retroflexus, with a notable reduction of weed biomass. No undesirable side effects on maize crop or soil quality, including microbial activity, were detected. Our results suggest that the incorporation of gorse and Scotch broom foliage is promising for pre-emergent weed control in maize; however, field trials that support and expand these glasshouse results are essentialThis research was funded by the Spanish Ministry of Economy and Competitiveness (http://www.mineco.gob.es/; BIOINPUT (CGL2016-78660-R)) (NP)S

Plant community and nutrient development within four estuary restoration sites in Kitsap County, Washington

Estuaries affected by physical barriers, such as culverts, experience reduced hydrological inputs and reduced connectivity resulting in the loss of ecological processes. To address reduction in ecological connectedness, culverts at three sites were removed and replaced with bridges. An observational field study was conducted in Kitsap County, Washington of three sites where culverts were replaced with bridges three, eight, and 13 years ago. Data was collected at a reference site where the estuary contains a culvert. It is hypothesized that estuary restoration will recover plant species, carbon sequestration, and nutrient cycling homogeneity above and below the restoration site. However, the length of time for recovery is not well understood. Soil and plant height was collected from random quadrats. Soil carbon and nitrogen were analyzed using an elemental analyzer and soil macro and micro-nutrients were analyzed using the Mehlich 3 Extraction method. Plant species richness was significantly higher (

Art399 Portfolio

Since beginning my journey as an artist, my muse has been found in nature and environmentalism. Natural imagery and symbolism can be used to invoke a viewer\u27s interest and curiosity. Mine focuses on invasive and native plant species as a lens for both environmental and social concerns. Through observation and extensive research my content and imagery take form in lithographs and screenprints. Most recently, I explored the relationship between the biodiversity crisis and songbirds, focusing on rural areas and attitudes toward this issue. Using plant imagery that are integral parts of the issue combined with manufactured effects such as glitching overlays on the birds the concept takes form. This implies an artificial glitch in the environment, such as when you take information out of a digital image\u27s code during the databending process. I am using common, relatively well-known birds such as Meadowlarks or Bobwhites that are usually identifiable to someone living in a rural community and allude to environmental issues already affecting those communities more than they realize. Similarly to artist Marilee Salvator, my work is very heavily influenced by extensive research and fact checking. Art like mine should be backed by factual evidence to strengthen its message and prevent the spread of false information. Of course that doesn’t mean it should read like an encyclopedia. Intense value shifts with pops of vibrant hues of color can create very breathtaking imagery. My linework and composition could be comparable to artist Jenny McCabe’s, although I do prefer to add more vibrant, less natural hues to shine line on human intervention in nature. Compositionally, it should be clear when two elements of a piece oppose each other as often is the case in my work.https://digitalcommons.murraystate.edu/art399/1143/thumbnail.jp

Predicting triadic closure in networks using communicability distance functions

We propose a communication-driven mechanism for predicting triadic closure in complex networks. It is mathematically formulated on the basis of communicability distance functions that account for the quality of communication between nodes in the network. We study $25$ real-world networks and show that the proposed method predicts correctly $20\%$ of triadic closures in these networks, in contrast to the $7.6\%$ predicted by a random mechanism. We also show that the communication-driven method outperforms the random mechanism in explaining the clustering coefficient, average path length, and average communicability. The new method also displays some interesting features with regards to optimizing communication in networks

EFECTO DE LA DENSIDAD Y TAMAÑO FLORAL SOBRE EL EXITO REPRODUCTIVO DE NOTHOSCORDUM GRAMINUM (ALLIACEAE

The size, form and color are signals used by flowers to attract their pollinators. Large and showy color flowers usuallyreceive higher pollinators visitation rates. According to the optimal forage theory, pollinators would tend to visitflower patches where they obtain the maximum reward regarding the energy expenditure in flower search. In highdensity patches, flowers are very close each other, hence, flower discrimination by pollinators would tend to be low.In low density patches, however, where the forage effort is greater, larger flowers are usually associated with higherrewards and would receive higher pollinators visitation achieving greater fitness than co-especifics with smallerflowers. In the present study we assessed the effects of flower density and size on the reproductive success (RS) ofNothoscordum gramineum. Four patches of different densities were delimited and the flowers size of the half ofindividuals at each patch was manually reduced. Results showed that RS was significantly greater in individuals withlarger flowers. Additionally, density has a positive effect on RS, especially in large size flowers. Nevertheless, fruitionsuccess reached maximum values in patches of intermediate density. Individuals with cut flowers did not varied the RSwith the variation of the density, suggesting that flower size is the most important attribute measured as advertisementby pollinators in N. gramineum. Our results do not support the hypothesis that in high density patches, flowerdisplays have low importance.El tamaño, la forma y el color son señales que utilizan las flores para atraer a sus polinizadores. Las flores que presentanun gran tamaño o alta vistosidad reciben una alta tasa de visitas de polinizadores. Según la teoría óptima de forrajeo, lospolinizadores tienden a visitar los parches donde disminuyan el esfuerzo del forrajeo y obtengan una mayor recompensa.En parches de la alta densidad las flores están agrupadas, razón por la cual la discriminación entre las flores tendería aser baja. Sin embargo, en parches de la baja densidad donde el esfuerzo de forrajeo es mayor, flores de mayor tamañorecibirían mayores tasas de visitas de polinizadores y manteniendo un mayor éxito reproductivo que individuos coespecíficos de menor tamaño. En el presente estudio determinamos el efecto de la densidad y del tamaño floral sobre eléxito reproductivo (ER) y el éxito de fructificación (EF) en la especie Nothoscordum gramineum. Cuatro parches dedistintas densidades fueron delimitados y el tamaño de las flores de la mitad de los individuos presentes en cada parchefue reducido manualmente. Los resultados demuestran que tanto la ER como EF son significativamente mayores en losindividuos con flores más grandes. Demostramos además que la densidad tiene un efecto positivo sobre el ER,principalmente en las flores de mayor tamaño. EF alcanzó valores máximos en los parches de densidades intermedias,disminuyendo en los de mayor densidad. Los resultados sugieren que el tamaño floral fue el atributo medido másimportante sobre la adecuación biológica de N. gramineum, debido a que los individuos de flores cortadas no respondieroncon la variación de la densidad. Nuestros resultados no permiten apoyar la hipótesis que en parches de alta densidad,los rasgos florales tendrían menor importancia, puesto que siempre ER y EF fueron mayores en flores enteras sinconsiderar la densidad, y las flores cortadas no demostraron un aumento en ER o EF con el aumento de la densidad

Information mobility in complex networks

The concept of information mobility in complex networks is introduced on the basis of a stochastic process taking place in the network. The transition matrix for this process represents the probability that the information arising at a given node is transferred to a target one. We use the fractional powers of this transition matrix to investigate the stochastic process at fractional time intervals. The mobility coefficient is then introduced on the basis of the trace of these fractional powers of the stochastic matrix. The fractional time at which a network diffuses 50% of the information contained in its nodes (1/ k50 ) is also introduced. We then show that the scale-free random networks display better spread of information than the non scale-free ones. We study 38 real-world networks and analyze their performance in spreading information from their nodes. We find that some real-world networks perform even better than the scale-free networks with the same average degree and we point out some of the structural parameters that make this possible