scholarly journals Relative contribution of ecological and biological attributes in the fine-grain structure of ant-plant networks

2015 ◽  
Author(s):  
Cecilia Díaz-Castelazo ◽  
Victor Rico-Gray
Keyword(s):  
Habitat Heterogeneity ◽  
Abiotic Factors ◽  
Grain Structure ◽  
Ecological Communities ◽  
Plant Interactions ◽  
Generalist Species ◽  
Facultative Mutualism ◽  
Interacting Species ◽  
Biotic Defense ◽  
Fine Grain

Background. Ecological communities of interacting species analyzed as complex networks, revealed that species dependence on their counterpart is more complex than expected at random. For ant-plant networks (mediated by extrafloral nectar), links among species are asymmetric (nested), forming a core of generalist species. Proposed factors affecting network organization include encounter probability (species abundances, habitat heterogeneity), behavior, phylogeny and body size. While the importance of underlying factors that influence structure of ant-plant networks have been separately explored, simultaneous contribution of several biological and ecological attributes inherent to the species, guild or habitat level have not been addressed. Methods. For a tropical seasonal site we recorded frequency of pairwise ant-plant interactions mediated by extrafloral nectaries, attributes of interacting species, habitat attributes, cover of plants with EFNs, and studied the resultant network structure. We addressed for the first time the role of mechanistic versus neutral determinants at the “fine-grain” structure (pairwise interactions) of ant-plant networks, studying the simultaneous contribution of several plant, ant, and habitat attributes in prevailing interactions as well as in overall network topology (community). Results. Our studied network was highly-nested, non-modular, with core species in general having high species strengths (higher strength values for ants than plants) and low specialization; plants had higher dependences on their counterparts. The significant factor explaining network and fine-grain structure was habitat heterogeneity in vegetation structure (open vs. shaded habitats), with no evidence of neutral (abundance) effects. Discussion. Core ant species are relevant to most plants species at the network, the latter depending more on the former, core ants showing adaptations to nectar consumption and deterrent behavior, suggestive of potential biotic defense at a community scale. At our study site spatiotemporal heterogeneity is so strong, that emerges at community-level structural properties, depicting influence of abiotic factors in facultative mutualism. Frequent occurrence of morphologically-diverse EFNs at all habitats suggests plasticity in plant strategies for biotic defense provided by ants.

scholarly journals Relative contribution of ecological and biological attributes in the fine-grain structure of ant-plant networks

2015 ◽  
Author(s):  
Cecilia Díaz-Castelazo ◽  
Victor Rico-Gray
Keyword(s):  
Habitat Heterogeneity ◽  
Abiotic Factors ◽  
Grain Structure ◽  
Ecological Communities ◽  
Plant Interactions ◽  
Generalist Species ◽  
Facultative Mutualism ◽  
Interacting Species ◽  
Biotic Defense ◽  
Fine Grain

Background. Ecological communities of interacting species analyzed as complex networks, revealed that species dependence on their counterpart is more complex than expected at random. For ant-plant networks (mediated by extrafloral nectar), links among species are asymmetric (nested), forming a core of generalist species. Proposed factors affecting network organization include encounter probability (species abundances, habitat heterogeneity), behavior, phylogeny and body size. While the importance of underlying factors that influence structure of ant-plant networks have been separately explored, simultaneous contribution of several biological and ecological attributes inherent to the species, guild or habitat level have not been addressed. Methods. For a tropical seasonal site we recorded frequency of pairwise ant-plant interactions mediated by extrafloral nectaries, attributes of interacting species, habitat attributes, cover of plants with EFNs, and studied the resultant network structure. We addressed for the first time the role of mechanistic versus neutral determinants at the “fine-grain” structure (pairwise interactions) of ant-plant networks, studying the simultaneous contribution of several plant, ant, and habitat attributes in prevailing interactions as well as in overall network topology (community). Results. Our studied network was highly-nested, non-modular, with core species in general having high species strengths (higher strength values for ants than plants) and low specialization; plants had higher dependences on their counterparts. The significant factor explaining network and fine-grain structure was habitat heterogeneity in vegetation structure (open vs. shaded habitats), with no evidence of neutral (abundance) effects. Discussion. Core ant species are relevant to most plants species at the network, the latter depending more on the former, core ants showing adaptations to nectar consumption and deterrent behavior, suggestive of potential biotic defense at a community scale. At our study site spatiotemporal heterogeneity is so strong, that emerges at community-level structural properties, depicting influence of abiotic factors in facultative mutualism. Frequent occurrence of morphologically-diverse EFNs at all habitats suggests plasticity in plant strategies for biotic defense provided by ants.

scholarly journals Relative contribution of ecological and biological attributes in the fine-grain structure of ant-plant networks

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8314
Author(s):  
Cecilia Díaz-Castelazo ◽  
Cristian A. Martínez-Adriano ◽  
Wesley Dáttilo ◽  
Victor Rico-Gray
Keyword(s):  
Vegetation Structure ◽  
Habitat Heterogeneity ◽  
Ecological Networks ◽  
Grain Structure ◽  
Asymmetric Structure ◽  
Ecological Communities ◽  
Plant Interactions ◽  
Generalist Species ◽  
Biotic Defense ◽  
Fine Grain

Background Ecological communities of interacting species analyzed as complex networks have shown that species dependence on their counterparts is more complex than expected at random. As for other potentially mutualistic interactions, ant-plant networks mediated by extrafloral nectar show a nested (asymmetric) structure with a core of generalist species dominating the interaction pattern. Proposed factors structuring ecological networks include encounter probability (e.g., species abundances and habitat heterogeneity), behavior, phylogeny, and body size. While the importance of underlying factors that influence the structure of ant-plant networks have been separately explored, the simultaneous contribution of several biological and ecological attributes inherent to the species, guild or habitat level has not been addressed. Methods For a tropical seasonal site we recorded (in 48 censuses) the frequency of pairwise ant-plant interactions mediated by extrafloral nectaries (EFN) on different habitats and studied the resultant network structure. We addressed for the first time the role of mechanistic versus neutral determinants at the ‘fine-grain’ structure (pairwise interactions) of ant-plant networks. We explore the simultaneous contribution of several attributes of plant and ant species (i.e., EFN abundance and distribution, ant head length, behavioral dominance and invasive status), and habitat attributes (i.e., vegetation structure) in prevailing interactions as well as in overall network topology (community). Results Our studied network was highly-nested and non-modular, with core species having high species strengths (higher strength values for ants than plants) and low specialization. Plants had higher dependences on ants than vice versa. We found that habitat heterogeneity in vegetation structure (open vs. shaded habitats) was the main factor explaining network and fine-grain structure, with no evidence of neutral (abundance) effects. Discussion Core ant species are relevant to most plants species at the network showing adaptations to nectar consumption and deterrent behavior. Thus larger ants interact with more plant species which, together with higher dependence of plants on ants, suggests potential biotic defense at a community scale. In our study site, heterogeneity in the ant-plant interactions among habitats is so prevalent that it emerges at community-level structural properties. High frequency of morphologically diverse and temporarily-active EFNs in all habitats suggests the relevance and seasonality of plant biotic defense provided by ants. The robust survey of ecological interactions and their biological/ecological correlates that we addressed provides insight of the interplay between adaptive-value traits and neutral effects in ecological networks.

Microstructure Development in a High Current Density NbTi Superconducting Composite

1985 ◽  
Vol 43 ◽  
pp. 186-189
Author(s):  
P. J. Lee ◽  
D. C. Larbalestier
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Cold Drawing ◽  
Heat Treatments ◽  
Grain Structure ◽  
Fine Grain ◽  
Boundary Film ◽  
Quantitative Basis ◽  
Cold Worked ◽  
Very High

Several features of the metallurgy of superconducting composites of Nb-Ti in a Cu matrix are of interest. The cold drawing strains are generally of order 8-10, producing a very fine grain structure of diameter 30-50 nm. Heat treatments of as little as 3 hours at 300 C (∼ 0.27 TM) produce a thin (1-3 nm) Ti-rich grain boundary film, the precipitate later growing out at triple points to 50-100 nm dia. Further plastic deformation of these larger a-Ti precipitates by strains of 3-4 produces an elongated ribbon morphology (of order 3 x 50 nm in transverse section) and it is the thickness and separation of these precipitates which are believed to control the superconducting properties. The present paper describes initial attempts to put our understanding of the metallurgy of these heavily cold-worked composites on a quantitative basis. The composite studied was fabricated in our own laboratory, using six intermediate heat treatments. This process enabled very high critical current density (Jc) values to be obtained. Samples were cut from the composite at many processing stages and a report of the structure of a number of these samples is made here.

CONTINUOUS-CAST 45-12 DUCTILE IRON

Alloy Digest ◽  
1989 ◽  
Vol 38 (4) ◽  
Keyword(s):  
Continuous Casting ◽  
Ductile Iron ◽  
Heat Treating ◽  
Grain Structure ◽  
Continuous Cast ◽  
Good Surface ◽  
Fine Grain ◽  
High Speeds ◽  
Good Surface Finish ◽  
Iron Grade

Abstract Ductile Iron grade 45-12 produced by continuous casting has consistent density and fine grain structure. It is the softest of the regular grades of ductile iron and it machines at high speeds with good surface finish. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, and tensile properties. It also includes information on heat treating, machining, and joining. Filing Code: CI-58. Producer or source: Federal Bronze Products Inc..

KETOS

Alloy Digest ◽  
1960 ◽  
Vol 9 (8) ◽  
Keyword(s):  
Physical Properties ◽  
Tensile Properties ◽  
Tool Steel ◽  
Heat Treating ◽  
Grain Structure ◽  
Steel Company ◽  
Fine Grain ◽  
Crucible Steel

Abstract KETOS is an oil-hardening non-deforming tool steel having deep hardening qualities with a fine grain structure. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as deformation. It also includes information on forming, heat treating, and machining. Filing Code: TS-96. Producer or source: Crucible Steel Company of America.

Ionic Conductivities of Doped CeO2 Thin Films as Related to Their Microstructure

1995 ◽  
Vol 411 ◽  
Author(s):  
Chunyan Tian ◽  
Siu-Wai Chan
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Ionic Conductivities ◽  
Dielectric Constants ◽  
Grain Structure ◽  
X Ray Diffraction ◽  
Fine Grain ◽  
Brick Layer Model ◽  
Columnar Grain ◽  
Beam Deposition

ABSTRACTThin films of 4% Y2O3 doped CeO2/Pd film/(001)LaA103 with a very low pinhole density were successfully prepared using electron-beam deposition technique. The microstructure of the films was characterized by x-ray diffraction and the electrical properties were studied as a function of temperature with AC impedance spectroscopy. A brick layer model was adopted to correlate the electrical properties to the microstructure of the films, which can be simplified as either a series or a parallel equivalent circuit associated with either a fine grain or a columnar grain structure, respectively. The conductivities of the films fell between the conductivities derived from the two circuit models, suggesting that the films are of a mixed fine grain and columnar grain structure. The measured dielectric constants of the films were found smaller than that of the bulk.

Magnetic properties of MnZn ferrite with ultra-fine grain structure

2003 ◽  
Vol 254-255 ◽  
pp. 538-540 ◽  
Author(s):  
J Moulin ◽  
Y Champion ◽  
J.M Grenèche ◽  
F Mazaleyrat
Keyword(s):  
Magnetic Properties ◽  
Grain Structure ◽  
Mnzn Ferrite ◽  
Fine Grain

The Possibility of Manufacturing Long-Length Metal Products with Ultra-Fine Grain Structure by Combination of Strain Effects

2016 ◽  
Vol 685 ◽  
pp. 487-491 ◽  
Author(s):  
Mikhail Chukin ◽  
Marina Polyakova ◽  
Alexandr Gulin ◽  
Olga Nikitenko
Keyword(s):  
Steel Wire ◽  
Continuous Method ◽  
Grain Structure ◽  
Strain Effect ◽  
Strain Effects ◽  
Fine Grain ◽  
Wide Range ◽  
Processing Modes ◽  
Efficiency Estimation ◽  
Metal Products

It is shown that combination of strain effects leads to possessing the ultra-fine grain structure in carbon wire. The continuous method of wire deformation nanostructuring was developed on the basis of simultaneous applying of tension deformation by drawing, bending deformation when going through the system of rolls and torsional deformation on a continuously moving wire. One of the main advantages of the developed method is that various hardware devices and tools already applied for steel wire production can be used to implement this method thus simplifying its introduction to the current industrial equipment. The efficiency estimation of the developed continuous method of deformation nanostructuring was carried out using carbon wire with different carbon content. It is shown that the mechanical properties of the wire after combination of different kinds of strain can vary over a wide range. This method makes it possible to choose such modes of strain effect, which can provide the necessary combination of strength and ductile properties of carbon wire depending on its further processing modes and application.

Microstructural Changes of Welded Zn-AI Alloy

1994 ◽  
Vol 367 ◽  
Author(s):  
Yao Hua Zhu
Keyword(s):  
Phase Transformation ◽  
Early Stage ◽  
Dendritic Structure ◽  
Metastable Phases ◽  
Grain Structure ◽  
Al Alloy ◽  
Cast State ◽  
Microstructural Changes ◽  
Fine Grain ◽  
Ageing Processes

AbstractExtruded eutectoid Zn-Al alloy was welded by a melt of the same eutectoid alloy. Two different microstructures were observed in the joint part and the bulk of the welded alloy. Typical dendritic structure of as cast Zn-Al alloy was observed in the joint part of the welded alloy. The bulk ofthe welded Zn-Al alloy appeared as fine grain structure. Two different metastable phases η'T decomposed from η's of chilled as cast state and η'E of extruded state were found to be unstable during early stage of ageing. A four phase transformation occurred after the decompositions of these two metastable phases of η'T. Microstructures of both joint part and bulk of the welded alloy were investigated parallely during ageing processes.

Role of grain boundaries in the epitaxial realignment of undoped and As-doped polycrystalline silicon films

1993 ◽  
Vol 8 (10) ◽  
pp. 2608-2612 ◽  
Author(s):  
C. Spinella ◽  
F. Benyaïch ◽  
A. Cacciato ◽  
E. Rimini ◽  
G. Fallico ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Structure ◽  
Native Oxide ◽  
Thermally Induced ◽  
Si Substrates ◽  
As Doping ◽  
Fine Grain ◽  
Si Films ◽  
Polycrystalline Silicon Films ◽  
Reduced Density

The early stages of the thermally induced epitaxial realignment of undoped and As-doped polycrystalline Si films deposited onto crystalline Si substrates were monitored by transmission electron microscopy. Under the effect of the heat treatment, the native oxide film at the poly-Si/c-Si interface begins to agglomerate into spherical beads. The grain boundary terminations at the interface are the preferred sites for the triggering of the realignment transformation which starts by the formation of epitaxial protuberances at these sites. This feature, in conjunction with the microstructure of the films during the first instants of the heat treatment, explains the occurrence of two different realignment modes. In undoped films the epitaxial protuberances, due to the fine grain structure, are closely distributed and grow together forming a rough interface moving toward the film's surface. For As-doped films, the larger grain size leaves a reduced density of realignment sites. Due to As doping some of these sites grow fast and form epitaxial columns that further grow laterally at the expense of the surrounding polycrystalline grains.

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