Miami University

About: Miami University is a education organization based out in Oxford, Ohio, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 9949 authors who have published 19598 publications receiving 568410 citations. The organization is also known as: Miami of Ohio & Miami-Ohio.

Nutrient recycling and herbivory as mechanisms in the “top–down” effect of fish on algae in lakes

Abstract: In lakes, top predators (fish) often influence the abundance of primary producers (phytoplankton) through food web interactions: phytoplankton biomass is often greater when planktivorous fish are abundant than when they are rare, and phytoplankton community structure is often affected by fish. Three mechanisms can account for these “top–down” effects of fish: decreased herbivory by zooplankton when fish biomass is high; modification of nutrient recycling rates by the herbivorous zooplankton assemblage as fish biomass varies; and nutrient recycling by fish. These processes were experimentally separated and their relative importance quantified in Tuesday Lake, Michigan. This was accomplished by manipulating the abundance of planktivorous fish or zooplankton in enclosures containing natural phytoplankton communities, and by incubating phytoplankton in nutrient-permeable chambers (which excluded herbivores) placed inside these enclosures. In large enclosures with all trophic levels, several phytoplankton taxa and total phytoplankton biomass showed increased abundance in the presence of fish compared to enclosures without fish. Several taxa also showed significantly greater abundance in nutrient-permeable chambers incubated in enclosures with fish than in chambers incubated in enclosures without fish. The latter result indicates that some phytoplankton taxa respond to fish even when separated from direct herbivory but exposed to nutrients recycled by consumers. Thus, consumer-mediated nutrient recycling had strong effects on phytoplankton community dynamics and could partly explain the “top–down” effects of fish. Most phytoplankton taxa responded to consumer-mediated nutrient recycling, especially dinoflagellates and chrysophytes. In separate enclosures, phytoplankton were exposed to contrasting zooplankton assemblages shaped by fish predation but without fish being present. The response of phytoplankton was not as strong as in the case of fish manipulations. Furthermore, the community-level response of phytoplankton was weaker in nutrient-permeable chambers placed in these enclosures than in chambers incubated in enclosures with fish. Nutrient limitation assays showed that manipulation of fish decreased phosphorus limitation of phytoplankton, while direct manipulation of zooplankton had no effect on phosphorus limitation. These results provide experimental evidence that food web effects on nutrient recycling are important in controlling phytoplankton community dynamics. Results also suggest that some of these effects are expressed via direct recycling of nutrients by fish, as well as by fish-induced effects on nutrient recycling by herbivores. Nutrient-mediated effects of top predators on primary producers should be incorporated into future models of “top–down” control of food web dynamics.

Competitive effects of the invasive shrub, Lonicera maackii (Rupr.) Herder (Caprifoliaceae), on the growth and survival of native tree seedlings

Abstract: Invasive plants are often associated with reduced cover of native plants, but rarely has competition between invasives and natives been assessed experimentally. The shrub Lonicera maackii, native to northeastern Asia, has invaded forests and old fields in numerous parts of eastern North America, and is associated with reduced tree seedling density in Ohio forests. A field experiment was conducted to test the effects of established L. maackii on the survival and growth of transplanted native tree species. The experiment examined above-ground competition (by removing L. maackii shoots) and below-ground competition (by trenching around transplanted seedlings). The effects of above-ground competition with L. maackii were generally more important than below-ground competition, though both were detected. Shoot treatment was the key determinant for the survival of all species except P. serotina, whereas trenching only enhanced survival for A. saccharum caged and P. serotina, and only in the shoot removal treatment. For the surviving seedlings, L. maackii shoot removal increased growth of A. saccharum seedlings protected with cages, but actually reduced the growth of unprotected Q. rubra and A. saccharum seedlings, indicating that L. maackii shoots confer some protection from deer browsing. Significant interactions between root and shoot treatment on Q. rubra growth parameters, specifically greatest growth in the shoot present & trenched treatment, is attributed to protection from deer browsing combined with release from below-ground competition. Despite this protective function of L. maackii shoots, the overall effect of this invasive shrub is increased mortality of native tree seedlings, suggesting it impacts the natural regeneration of secondary forests.

Revised definition of optical flow: integration of radiometric and geometric cues for dynamic scene analysis

Abstract: Optical flow has been commonly defined as the apparent motion of image brightness patterns in an image sequence. In this paper, we propose a revised definition to overcome shortcomings in interpreting optical flow merely as a geometric transformation field. The new definition is a complete representation of geometric and radiometric variations in dynamic imagery. We argue that this is more consistent with the common interpretation of optical flow induced by various scene events. This leads to a general framework for the investigation of problems in dynamic scene analysis, based on the integration and unified treatment of both geometric and radiometric cues in time-varying imagery. We discuss selected models, including the generalized dynamic image model, for the estimation of optical flow. We show how various 3D scene information are encoded in, and thus may be extracted from, the geometric and radiometric components of optical flow. We provide selected examples based on experiments with real images.

Nomenclature of the apatite supergroup minerals

Abstract: The apatite supergroup includes minerals with a generic chemical formula IX M12 VII M23( IV TO4)3 X( Z ¼ 2); chemically they can be phosphates, arsenates, vanadates, silicates, and sulphates. The maximum space group symmetry is P63/m, but several members of the supergroup have a lower symmetry due to cation ordering and deviations from the ideal topology, which may result in an increase of the number of the independent sites. The apatite supergroup can be formally divided into five groups, based on crystal-chemical arguments: apatite group, hedyphane group, belovite group, britholite group, and ellestadite group. The abundance of distinct ions which may be hosted at the key-sites (M ¼ Ca 2þ , Pb 2þ , Ba 2þ , Sr 2þ , Mn 2þ , Na þ , Ce 3þ , La 3þ ,Y 3þ , Bi 3þ ;T ¼ P 5þ , As 5þ ,V 5þ , Si 4þ ,S 6þ ,B 3þ ;X ¼ F � , (OH) � , Cl � ) result in a large number of compositions which may have the status of distinct mineral species. Naming of apatite supergroup minerals in the past has resulted in nomenclature inconsistencies and problems. Therefore, an ad hoc IMA-CNMNC Subcommittee was established with the aim of rationalizing the nomenclature within the apatite supergroup and making some order among existing and potentially new mineral species. In addition to general recommendations for the handling of chemical (EPMA) data and for the allocation of ions within the various sites, the main recommendations of this subcommittee are the following: 1. Nomenclature changes to existing minerals. The use of adjectival prefixes for anions is to be preferred instead of modified Levinson suffixes; accordingly, six minerals should be renamed as follows: apatite-(CaF) to fluorapatite, apatite-(CaOH) to hydroxylapatite, apatite-(CaCl) to chlorapatite, ellestadite-(F) to fluorellestadite, ellestadite-(OH) to hydroxylellestadite, phospho- hedyphane-(F) to fluorphosphohedyphane. For the apatite group species these changes return the names that have been used in thousands of scientific paper, treatises and museum catalogues over the last 150 years. The new mineral IMA 2008-009, approved without a name, is here named stronadelphite. Apatite-(SrOH) is renamed fluorstrophite. Deloneite-(Ce) is renamed deloneite. The new mineral IMA 2009-005 is approved with the name fluorbritholite-(Y).

Nine New Phosphorene Polymorphs with Non-Honeycomb Structures: A Much Extended Family

Abstract: We predict a new class of monolayer phosphorus allotropes, namely, e-P, ζ-P, η-P, and θ-P. Distinctly different from the monolayer α-P (black) and previously predicted β-P (Phys. Rev. Lett. 2014, 112, 176802), γ-P, and δ-P (Phys. Rev. Lett. 2014, 113, 046804) with buckled honeycomb lattice, the new allotropes are composed of P4 square or P5 pentagon units that favor tricoordination for P atoms. The new four polymorphs, together with five additional hybrid polymorphs, greatly enrich the phosphorene structures, and their stabilities are confirmed by first-principles calculations. In particular, the θ-P is shown to be equally stable as the α-P (black) and more stable than all previously reported phosphorene polymorphs. Prediction of nonvolatile ferroelastic switching and structural transformation among different polymorphs under strains points out their potential applications via strain engineering.