Dispersal Relationships Research Articles

Numerical investigation of simply supported periodic rectangular plates with acoustic black hole wedge

In this paper, we propose the periodic rectangle plate with one-dimensional acoustic black hole (ABH) wedge under the simply supported condition. The vibration performances have been investigated by the semi-analytic method based on the levy solution method combined with WKB approximation, which is also validated by finite element method (FEM) simulation. For the rectangle ABH wedge, we derive the flexural wave dispersive relationship in plate, which also revealed the cut-on frequency. It can also be found that with the increase of periodic number, the vibration of plate structure can be reduced not only in the high frequency range where traditional ABH effect takes effect, but in low and middle frequency range the periodic ABH wedge can also show its advantage. Meanwhile, the damping coupling performance between the periodic ABH wedge and attached damping layers has also been investigated to enhance the vibration reduction. This novel kind ABH structure shows its potential in engineering applications.

Uncovering the Challenges and Cornerstones for the Governance of an Innovation Ecosystem in Organic and Agroecological Agriculture

The concept of innovation ecosystems brigs to light a whole set of stakeholders that face an entire set of barriers to making new technologies change people’s lives. This research aimed to understand and analyze the innovation ecosystem in organic and agroecological production in the Federal District, Brazil, and its directly influenced area. The purpose was to analyze the role of each stakeholder in ecosystem governance and build strategies for boosting organic food value chains in the territory. A questionnaire was applied to 27 institutions identified as the potential backbone of the innovation ecosystem. The Gephi 0.10.1 software and the Force Atlas 2 network algorithm set up the relationship network. We verified a certain misalignment between expected roles and functions performed by 66% of the stakeholders. Low integration and dispersed relationships in the network were observed with a misalignment around the innovation concept in organic food production. This arrangement of the ecosystem is compatible with an initial stage, in which stakeholders and resources would be spread out and demobilized. Although shared governance is the most effective for an innovation ecosystem, the analyzed ecosystem demands centralized governance with a leading organization. Strengthening strategies were proposed to (i) define leadership, (ii) define roles or competencies, and (iii) strengthen community attributes.

The functional diversity-productivity relationship of woody plants is climatically sensitive.

Plot-scale experiments indicate that functional diversity (FD) plays a pivotal role in sustaining ecosystem functions such as net primary productivity (NPP). However, the relationships between functional diversity and NPP across larger scale under varying climatic conditions are sparsely studied, despite its significance for understanding forest-atmosphere interactions and informing policy development. Hence, we examine the relationships of community-weighted mean (CWM) and functional dispersion (FDis) of woody plant traits on NPP across China and if such relationships are modulated by climatic conditions at the national scale. Using comprehensive datasets of distribution, functional traits, and productivity for 9120 Chinese woody plant species, we evaluated the distribution pattern of community-weighted mean and functional dispersion (including three orthogonal trait indicators: plant size, leaf morphology, and flower duration) and its relationships with NPP. Finally, we tested the effects of climatic conditions on community-weighted mean/functional dispersion-NPP relationships. We first found overall functional diversity-NPP relationships, but also that the magnitude of these relationships was sensitive to climate, with plant size community-weighted mean promoting NPP in warm regions and plant size functional dispersion promoting NPP in wet regions. Second, warm and wet conditions indirectly increased NPP by its positive effects on community-weighted mean or functional dispersion, particularly through mean plant size and leaf morphology. Our study provides comprehensive evidence for the relationships between functional diversity and NPP under varying climates at a large scale. Importantly, our results indicate a broadening significance of multidimensional plant functional traits for woody vegetation NPP in response to rising temperatures and wetter climates. Restoration, reforestation actions and natural capital accounting need to carefully consider not only community-weighted mean and functional dispersion but also their interactions with climate, to predict how functional diversity may promote ecosystem functioning under future climatic conditions.

Alternative measures of trait-niche relationships: A test on dispersal traits in saproxylic beetles.

Functional trait approaches are common in ecology, but a lack of clear hypotheses on how traits relate to environmental gradients (i.e., trait-niche relationships) often makes uncovering mechanisms difficult. Furthermore, measures of community functional structure differ in their implications, yet inferences are seldom compared among metrics. Community-weighted mean trait values (CWMs), a common measure, are largely driven by the most common species and thus do not reflect community-wide trait-niche relationships per se. Alternatively, trait-niche relationships can be estimated across a larger group of species using hierarchical joint species distribution models (JSDMs), quantified by a parameter Γ. We investigated how inferences about trait-niche relationships are affected by the choice of metric. Using deadwood-dependent (saproxylic) beetles in fragmented Finnish forests, we followed a protocol for investigating trait-niche relationships by (1) identifying environmental filters (climate, forest age, and deadwood volume), (2) relating these to an ecological function (dispersal ability), and (3) identifying traits related to this function (wing morphology). We tested 18 hypothesized dispersal relationships using both CWM and Γ estimates across these environmental gradients. CWMs were more likely than Γ to show support for trait-niche relationships. Up to 13% of species' realized niches were explained by dispersal traits, but the directions of effects were consistent with fewer than 11%-39% of our 18 trait-niche hypotheses (depending on the metric used). This highlights the difficulty in connecting morphological traits and ecological functions in insects, despite the clear conceptual link between landscape connectivity and flight-related traits. Caution is thus warranted in hypothesis development, particularly where apparent trait-function links are less clear. Inferences differ when CWMs versus Γ estimates are used, necessitating the choice of a metric that reflects study questions. CWMs help explain the effects of environmental gradients on community trait composition, whereas the effects of traits on species' niches are better estimated using hierarchical JSDMs.

Simulation approach to electron transport phenomenon in graphene

This investigation was originally designed to verify that the tight-binding approach utilizes an amalgamation of estimated wave functions to compute the electrical band structure. Utilizing computational tools has become essential, especially for challenging and dull problems in physics. Computer programs, in general, once utilized in the approved manner, allow physical problems to be solved and explained rapidly and efficiently at the same time. The case then is to comprehend how to swap from the abstract equations to the computer program, i.e., codes. In this research, valid and numerical strategies are utilized to examine the electrical characteristics of 2D crystals through fluctuating geometries and magnetic fields. Certainty in the mathematical model is based upon those assessments of the two procedures utilizing the dispersal relationship and density of states. The numerical strategies become the importance as the examined systems goes into more complex to be investigated precisely. Throughout this study, it is confirmed that the tight-binding model utilizes a superposition of estimated wave functions to estimate the electrical band structure. This model was showed to a four-sided network and a hexagonal network to confirm the characteristics of electrons as they move over the graphene network. Particularly, this setup provides a way of investigating energy-reliant transport in graphene. The outcomes of this investigation are significant since the energy dependance of transport in mesoscopic graphene is the core of numerous odd transportation occurrences. Also, the conductance for the four-sided framework is considered utilizing the mathematical approaches and shows the accurate appearances for the quantum Hall effect.

The relationship of dispersion and properties of powder materials on the example of titanium oxide bronze

The subject of this work is oxide potassium-titanium bronzes.
 The purpose of the work: to establish the relationship between the dispersion of samples of oxide potassium-titanium bronze and its physicochemical properties.
 Synthesis methods: self-propagating high-temperature synthesis (SHS), mechanosynthesis. Research methods used in the work: X-ray phase analysis (XRF), optical method for determining particle size, four-probe method for determining electrical conductivity, thermal analysis, method for determining chemical resistance.
 Results of the study: particle sizes were determined, which are 400, 200 and 40 nm. The work is devoted to the study of the influence of fineness on the structure and physicochemical properties of compounds of variable composition on the example of titanium oxide bronzes. A nanocrystalline sample of oxide potassium-titanium bronze was obtained by mechanosynthesis, coarse powders were obtained by SHS. The obtained samples were identified by X-ray phase analysis. The optical method of analysis determined the particle sizes, which are 400, 200 and 40 nm. It has been established that nanocrystalline samples of oxide potassium-titanium bronze are less resistant to aggressive media. Reducing the particle size does not affect the thermal stability. In the transition to nanoscale, the specific electrical conductivity increases by 1.5 times and amounts to 0,076 Ohm-1cm-1. The volume density of defects in the nanocrystalline structure of oxide potassium-titanium bronze is calculated, which is 1013 cm-2.

SHREDDING, BURNING, TUNNELLING

This essay marks the centenary of 1922, annus mirabilis of modernism but also the year when my grandparents became child refugees in the Asia Minor Catastrophe. In Mrs. Dalloway and her Diary, Virginia Woolf offers a figuration of modernity, which Toni Morrison critically revises in her master’s thesis and in Sula. I aim to show that Sula displays a fine-grained, pervasive and dispersive intertextual relationship with Mrs. Dalloway: a multi-form critical repetition, centred around the figures of shredding, burning and tunnelling; I then connect these figures to the lives of my grandparents. The figures that Woolf and Morrison develop anticipate and might indeed have influenced poststructuralist theory, particularly Gilles Deleuze and Félix Guattari’s concept of the rhizome.

Passive directed dispersal of plants by animals

Conceptual gaps and imprecise terms and definitions may obscure the breadth of plant-animal dispersal relationships involved in directed dispersal. The term 'directed' indicates predictable delivery to favourable microsites. However, directed dispersal was initially considered uncommon in diffuse mutualisms (i.e. those involving many species), partly because plants rarely influence post-removal propagule fate without specialized adaptations. This rationale implies that donor plants play an active role in directed dispersal by manipulating vector behaviour after propagule removal. However, even in most classic examples of directed dispersal, participating plants do not influence animal behaviour after propagule removal. Instead, such plants may take advantage of vector attraction to favourable plant microsites, indicating a need to expand upon current interpretations of directed dispersal. We contend that directed dispersal can emerge whenever propagules are disproportionately delivered to favourable microsites as a result of predictably skewed vector behaviour. Thus, we propose distinguishing active and passive forms of directed dispersal. In active directed dispersal, the donor plant achieves disproportionate arrival to favourable microsites by influencing vector behaviour after propagule removal. By contrast, passive directed dispersal occurs when the donor plant takes advantage of vector behaviour to arrive at favourable microsites. Whereas predictable post-removal vector behaviour is dictated by characteristics of the donor plant in active directed dispersal, characteristics of the destination dictate predictable post-removal vector behaviour in passive directed dispersal. Importantly, this passive form of directed dispersal may emerge in more plant-animal dispersal relationships because specialized adaptations in donor plants that influence post-removal vector behaviour are not required. We explore the occurrence and consequences of passive directed dispersal using the unifying generalized gravity model of dispersal. This model successfully describes vectored dispersal by incorporating the influence of the environment (i.e. attractiveness of microsites) on vector movement. When applying gravity models to dispersal, the three components of Newton's gravity equation (i.e. gravitational force, object mass, and distance between centres of mass) become analogous to propagules moving towards a location based on characteristics of the donor plant, the destination, and relocation processes. The generalized gravity model predicts passive directed dispersal in plant-animal dispersal relationships when (i) animal vectors are predictably attracted to specific destinations, (ii) animal vectors disproportionately disperse propagules to those destinations, and (iii) those destinations are also favourable microsites for the dispersed plants. Our literature search produced evidence for these three conditions broadly, and we identified 13 distinct scenarios where passive directed dispersal likely occurs because vector behaviour is predictably skewed towards favourable microsites. We discuss the wide applicability of passive directed dispersal to plant-animal mutualisms and provide new insights into the vulnerability of those mutualisms to global change.

Broadband vibration suppression of graded/disorder piezoelectric metamaterials

This paper investigates the attenuation behavior of flexural waves in functionally graded and disordered piezoelectric metamaterials. These structures are expediently designed by tuning the shunted piezoelectric electrical circuit. The transfer matrix method is employed to calculate the dispersive relationship of one-dimensional graded piezoelectric meta beams. It is found that the attenuation zone of the graded arrangement becomes wider compared with the result of the corresponding periodic structures. Moreover, the attenuation zone becomes wider by increasing the capacitance ratio’s absolute value in a specific region. We demonstrate that the graded system generating the rainbow effect can slow down the flexural wave propagation in the host structure and increase the interaction time between elastic waves and local electrical circuits through the time-domain analysis. Besides, we study further the two-dimensional graded and disordered piezoelectric meta plates. Numerical results show that the bandwidth of the latter on average is broader than that of the former. Moreover, the disordered system can keep the continuity of the dominant attenuation zone and further increase the attenuation bandwidth within the larger capacitance ratio. These graded and disorder configuration concepts may pave a new way for elastic wave manipulation to realize broadband vibration suppressions and frequency selective spatial separations.

Curcumin solid dispersion based on three model acrylic polymers: formulation and release properties

To investigate structure-property relationship of polymer-based curcumin solid dispersion (SD), three acrylic polymers were used to formulate curcumin SD by solvent evaporation method. Curcumin Eudragit EPO SD (cur@EPO), curcumin Eudragit RS PO SD (cur@RSPO) and curcumin Eudragit RL PO SD (cur@RLPO) showed deep red, golden orange and reddish orange color, respectively. Cur@RSPO entrapped 15.42 wt% of curcumin followed by cur@RL PO and cur@EPO. FTIR spectra indicated that in cur@EPO, curcumin may transfer hydrogen to the dimethylaminoethyl methacrylate group and thus change its color to red. In contrast, curcumin may form hydrogen bonding with Eudragit RS PO and Eudragit RL. Curcumin exists in amorphous state in three SDs as proved by differential scanning calorimetry and X-Ray diffraction measurement. In vitro digestion presented that lower pH value in simulated gastric fluid (SGF) stimulates the curcumin release from cur@EPO while permeability influences the release profile in other two SDs. When in simulated intestinal fluid (SIF), first order release model governs the release behaviors of all three SDs which showed sustained release pattern. Our results are helpful to elucidate how structure of polymer may impact on the major properties of curcumin contained SD and will be promising to broaden its therapeutic applications.

Species-specific interactions in avian-bryophyte dispersal networks.

Studies from seed plants have shown that animal dispersal fundamentally alters the success of plant dispersal, shaping community composition through time. Our understanding of this phenomenon in spore plants is comparatively limited. Though little is known about species-specific dispersal relationships between passerine birds and bryophytes, birds are particularly attractive as a potential bryophyte dispersal vector given their highly vagile nature as well as their association with bryophytes when foraging and building nests. We captured birds in Gifford Pinchot National Forest to sample their legs and tails for bryophyte propagules. We found 24 bryophyte species across 34 bird species. We examined the level of interaction specificity: (i) within the overall network to assess community level patterns; and (ii) at the plant species level to determine the effect of bird behaviour on network structure. We found that avian–bryophyte associations are constrained within the network, with species-specific and foraging guild effects on the variety of bryophytes found on bird species. Our findings suggest that diffuse bird–bryophyte dispersal networks are likely to be common in habitats where birds readily encounter bryophytes and that further work aimed at understanding individual bird–bryophyte species relationships may prove valuable in determining nuance within this newly described dispersal mechanism.

Modeling Dispersive Media in Finite-Difference Time-Domain Method for Radiative Cooling Applications

Radiative cooling offers a new strategy to address building cooling problems in an environmentally friendly way, compared with traditional cooling methods that require high-power consumption. The goal of radiative cooling is to maximize absorption at the mid-infrared (MIR) spectrum (8– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$13~\mu m$ </tex-math></inline-formula> ). Thus, it is important to characterize the dispersive relationship of the radiative cooling materials (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , SiC, SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) in the MIR regime. In this work, we use the multi-pole Lorentz dispersion equation to model frequency-dependent dielectric constants of radiative cooling materials, which requires particle swarm optimization to solve multidimension optimization problems. This modeling can be directly applicable to the auxiliary differential equation (ADE)-based finite-difference time-domain (FDTD) method for simulating emissivity of radiative cooling materials. Further, we limit the number of Lorentz poles to five, which minimizes the computational burden in ADE–FDTD. Then, we validate our FDTD results against an analytic prediction calculated by the transfer matrix method. Finally, we demonstrate a highly efficient radiative cooling structure based on a simple SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> grating. The proposed material modeling can accelerate the nano/microstructural design of the radiative cooling strategies.

Variability of bio-optical properties in nearshore waters of the estuary and Gulf of St. Lawrence: Absorption and backscattering coefficients

The inherent optical properties and the optically significant constituents in nearshore zones of the Estuary and Gulf of St. Lawrence (EGSL), eastern Canada, were systematically investigated. Dry-mass concentrations of dissolved organic carbon (DOC), phytoplankton pigments, and suspended particulate matter (SPM) were determined together with the absorption coefficients of chromophoric dissolved organic matter, acdom; non-algal particles, anap; phytoplankton, aphy; and particulate backscattering coefficient, bbp. The sampling design allowed analysis at different spatial scales and considered some intra-regional differences in distinctive zones (subregions) of the EGSL's north shore (separated by ∼ 102 km), as well as within subregions (samples separated by ∼ 100–101 km). Temporal analysis focused on seasonal variability (sampling time separated by ∼ 101–102 days). Optical indices, such as the spectral slopes of acdom and anap, pigment ratios, mass-specific absorption and backscattering coefficients, and particulate matter fractioning (inorganic and organic) allowed a detailed characterization of the dissolved organic matter pool and provided useful information about particulate matter assemblages. The acdom was highly correlated with DOC and was found to have a conservative mixing behavior as the dominant process controlling its distribution, although differences among and within subregions were noted and related to differences in local river endmembers and seasonality. The acdom also dominated the absorption budget, even in long wavelengths of the visible range (e.g., 550 nm). Despite the highly light-absorptive characteristic of the waters, phytoplankton biomass was not negligeable, as shown by the chlorophyll-a (Chla) concentrations means that were almost always greater than 1 mg m−3. Analysis of the spectral shape of aphy and pigment ratios revealed a seasonal modulation in the composition of phytoplankton assemblages and photoacclimation. The optical properties of particulate matter showed a very dispersed relationship when compared to dry-mass concentration proxies in the study area, but the extremely low SPM-specific bbp values encountered were explained by the organic-rich characteristic of the nearshore zones of the EGSL. Short-term variability (atmospheric events) and the hydrodynamical regime also resulted in substantial variability in the optical properties of these areas. Overall, we provide a general parametrization for the relationships among the investigated inherent optical properties and dry-mass concentrations, which, in turn, will provide a baseline for tuning and developing regional remote sensing algorithms for the retrieval of biogeochemically relevant constituents of the water.

Complex relationships between beta diversity and dispersal in meta‐community models

Dispersal is one of the most important drivers of community assembly. Understanding how dispersal impacts spatial variations in community composition (beta diversity) is crucial for predicting biodiversity change during the Anthropocene. Classic theories and a large amount of empirical evidence have led to a common belief that increasing dispersal rate should lead to regional community homogenization (lower beta diversity). However, recent empirical studies show that increasing dispersal can also lead to regional community divergence when interacting with other processes such as disturbance and priority effect. The underappreciation of the complex relationship between beta diversity and dispersal might impede our ability to make accurate ecological forecasts. To address this concern, I examine the beta diversity–dispersal relationship through extinction and colonization dynamics in meta‐community models. I find that a wide range of beta diversity–dispersal relationships (e.g. negative, positive, hump‐shaped) can be generated by changes in species‐level occurrence probabilities when meta‐population dispersal (rather than mainland–island dispersal), disturbance and strong biotic interactions are at play. Specifically, reducing the variance of species‐level occurrence probabilities leads to community divergence and increasing the mean occurrence probability leads to community homogenization; a positive or hump‐shaped beta diversity–dispersal relationship emerges when the effect of the decreasing variance is stronger than the effect of increasing mean. These findings highlight the intrinsic constraint of occupancy stochasticity on beta diversity changes and echo the call for more realistic manipulations of stochastic dispersal and a detailed understanding of the interaction networks to test various beta diversity–dispersal relationships in future empirical studies.

Structure-Solubility Relationship of CO Dispersion in Model Hydrocarbon Liquids and Heavy Oil Fractions.

The solubility of CO in heavy oils is an important parameter for designing and optimizing the partial upgrading process of heavy oil under CO/syngas and water. To study the structure–solubility relationship of CO dispersion in organic liquids, the solubility of CO in hydrocarbons (n-hexane, n-octane, n-hexadecane, cyclohexane, toluene, and 1-methylnaphthalene), petroleum distillates, and residues from Canadian oil sand bitumen was measured at different temperatures and pressures. The dispersion behavior of CO in different molecules was simulated by the molecular dynamics calculation. The role of water on CO dispersion in these systems was also explored. Experimental data show that the increase of both paraffinic chain length and aromaticity of molecules could hinder the dissolution of CO. By theoretical calculation, it is found that n-hexadecane and 1-methylnaphthalene present the strongest self-aggregation tendency, resulting in the low interaction with CO. The intermolecular forces of hydrocarbons appear to be the key factor determining the CO solubility. The dissolved H2O molecules could weaken the intermolecular forces of hydrocarbons and thus increase the CO solubility. Based on the model system study, the solubility of CO in complex petroleum distillates and heavy residues is rationalized by their molecular composition, which is mainly dependent on the relative proportion of paraffins to aromatics.

Similar seed dispersal systems by local frugivorous birds in native and alien plant species in a coastal seawall forest.

Frugivorous birds play an important role in seed dispersal. Alien plant species’ seeds are dispersed by local birds in order to establish populations in new habitats. Alien plant species that produce fruits similar to that of native species have the potential to attract local birds, creating new mutualistic systems that are similar to the local ones. In autumn 2018 and 2019, we studied the seed dispersal systems of an alien plant species, Phytolacca americana, and a native species, Cayratia japonica, in a coastal seawall forest. Both plant species’ fruit, frugivorous bird foraging behaviors, seed germination rates, and seedling microhabitats were examined to determine whether the alien species had a similar seed dispersal system to that of the native species. Our results showed that P. americana and C. japonica had similar fruit type, color, and ripening period. There was a positive correlation between the percentage rate of fruit ripening and the percentage rate of fruit missing for both plant species, indicating that local frugivorous birds have the potential to sufficiently disperse the alien seeds to enable its spread in the coastal seawall forest (simple linear regression, P. americana: β = 0.863 ± 0.017, R2adj = 0.978, P < 0.01; C. japonica: β = 0.787 ± 0.034, R2adj = 0.898, P < 0.01). Eleven bird species consumed the fruits of the alien species or native species during the study period. Similar results were shown across alien and native species in bird foraging behavior (feeding frequency, feeding duration and first stop distance) indicating that a similar seed dispersal relationship had been established between local frugivorous and both plant species. The alien plant had a higher number of fruits carried by birds, suggesting that P. americana had a slightly higher fruit consumption than that of C. japonica (t-test, P < 0.01). Alien plant seedlings grow more abundant in forest gap microhabitat (t-test, P < 0.01). Our results confirmed that bird digestion promotes seed germination success in both plant species. Our study suggests that in a narrow coastal seawall forest, alien plant species can successfully establish their populations by relying on similar seed dispersal systems as the local species.

Societies of local populations in African great apes – dispersal, extra-group paternity, and intergroup relationships

Societies of local populations in African great apes – dispersal, extra-group paternity, and intergroup relationships

Deciphering sample size effect on microbial biogeographic patterns and community assembly processes at centimeter scale

Revealing the effects of spatial heterogeneity on microorganisms is crucial for the further understanding of microbial diversity, turnover and ecological processes. However, microbial community assembly and the factors that shape it are still unknown at a centimeter scale. To address this gap, we conducted variation partitioning and null model analyses on the microbial community composition of a soil cube, divided into up to 64 sub-cubes, to investigate microbial biogeographic patterns and microbial assembly processes of 3 cm-scale sampling schemes. The results suggested that microbial community was more dispersed and distance decay relationships were more significant in sampling schemes of smaller sample size compared with those of larger sample size. We further investigated the relative importance of ecological processes and demonstrated that bacterial community assembly processes changed from variable selection to homogenous selection as the sample size increased. The importance of spatial distance and micro-environmental variables in shaping and maintaining microbial diversity was emphasized by the dynamics of spatial heterogeneity and environmental filtering. As microorganisms are spatially distributed in soil, this sampling scale dependent diversity and assembly suggests that microbial ecology questions need to be considered in more dimensions than they usually are.

The "evil tribe" spreads across the land: A dated molecular phylogeny provides insight into dispersal, expansion, and biogeographic relationships within one of the largest tribes of the sunflower family (Vernonieae: Compositae).

PREMISEWith over 1500 species, the globally distributed Vernonieae is one of the most successful members of the largest family of flowering plants, the Compositae. However, due to its morphological complexity and limited geographic representation in previous studies, subtribal and biogeographic relationships are unclear. Here, new DNA sequence data spanning the geographic range of the tribe provides a taxonomically robust time‐calibrated phylogeny, estimates migration pathways and timing of important biogeographic events, and allows inference of environmental factors that have contributed to the success of the Vernonieae worldwide.METHODSPhylogenetic relationships were estimated for 368 taxa representing all Vernonieae subtribes. Molecular clock and ancestral range estimation analyses provide a framework for inference of the biogeographic history of the tribe.RESULTSRelationships among the subtribes were established and correct placement determined for problematic taxa, along with the first model‐based assessment of the biogeographic history of the tribe. The Vernonieae were estimated to have evolved ~50 mya. Africa was the first center of diversity, from which a single dispersal event established the monophyletic New World lineage. Long‐distance dispersal from Africa and Brazil established the tribe on five continents and Oceania.CONCLUSIONSThe New World lineage is monophyletic, but Old World taxa are not. New subtribal taxonomies are needed. Moquinieae are nested in Vernonieae. Long‐distance dispersal from Africa beginning 45 mya was key to establishing the tribe’s near‐global distribution. Migration corridors created by volcanic mountain chains and iron‐rich soils in Africa and the Americas promoted radiation and range expansion.

"Relationship of Rheology, Fiber Dispersion, and Strengths of Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites"

"Relationship of Rheology, Fiber Dispersion, and Strengths of Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites"