Pollination syndromes ignored: importance of non-ornithophilous flowers to Neotropical savanna hummingbirds

Generalization prevails in flower–animal interactions, and although animal visitors are not equally effective pollinators, most interactions likely represent an important energy intake for the animal visitor. Hummingbirds are nectar-feeding specialists, and many tropical plants are specialized toward hummingbird-pollination. In spite of this, especially in dry and seasonal tropical habitats, hummingbirds may often rely on non-ornithophilous plants to meet their energy requirements. However, quantitative studies evaluating the relative importance of ornithophilous vs. non-ornithophilous plants for hummingbirds in these areas are scarce. We here studied the availability and use of floral resources by hummingbirds in two different areas of the Cerrado, the seasonal savannas in Central Brazil. Roughly half the hummingbird visited plant species were non-ornithophilous, and these contributed greatly to increase the overall nectar availability. We showed that mean nectar offer, at the transect scale, was the only parameter related to hummingbird visitation frequency, more so than nectar offer at single flowers and at the plant scale, or pollination syndrome. Centrality indices, calculated using hummingbird–plant networks, showed that ornithophilous and non-ornithophilous plants have similar importance for network cohesion. How this foraging behaviour affects reproduction of non-ornithophilous plants remains largely unexplored and is probably case specific, however, we suggest that the additional energy provided by non-ornithophilous plants may facilitate reproduction of truly ornithophilous flowers by attracting and maintaining hummingbirds in the area. This may promote asymmetric hummingbird–plant associations, i.e., pollination depends on floral traits adapted to hummingbird morphology, but hummingbird visitation is determined more by the energetic "reward" than by pollination syndromes.     

Simulations and experiments in punching spring-steel devices with sub-millimeter features

This work demonstrates the feasibility of meso-scale (100 μm to mm) punching of multiple holes of intricate shapes in metals. Analytical modeling, finite element (FE) simulation, and experimentation are used in this work. Two-dimensional FE simulations in ABAQUS were done with an assumed material modeling and plane-strain condition. A known analytical model was used and compared with the ABAQUS simulation results to understand the effects of clearance between the punch and the die. FE simulation in ABAQUS was done for different clearances and corner radii of the punch, die, and holder. To complement modeling with real experiments and for the purpose of comparison, a set of punches and dies were made to punch out a miniature spring-steel gripper. Comparison of compliant grippers made by wire-cut electro discharge machining (EDM) and punching shows that realizing sharp interior and re-entrant corners by punching is not easy to achieve. However, the promise of realizing meso-scale parts with complicated shapes through punching is demonstrated in this work; and further work is identified and some strategies are suggested for improvement. The main contribution of this paper is in adapting the well-established punching and blanking operations to the meso-scale as a viable alternative to making miniature devices currently dominated by lithography-based techniques.     

Investigation on the changes effected by tool profile on mechanical and tribological properties of friction stir processed AZ31B magnesium alloy

The present study investigates the effect of tool shoulder profile on the mechanical and tribological properties of friction stir processed AZ31B magnesium alloy. The tool rotational speed and feed rate are the chosen process parameters. The experiments were conducted with 3 level 2 factors full factorial design. The recorded responses were tensile strength, wear losses and corrosion rate. The results were analyzed with the help microstructures of the processed samples. The study reveals that, for concave shoulder tool, the strain hardening effect was playing a major role in determining the properties of the processed materials and for the step shoulder tool, the grain size plays a major role in determining the properties of the processed materials.     

Design and evaluation of an atomization-based cutting fluid spray system in turning of titanium alloy

Tool life has been a vital issue in machining titanium alloys. Recently, an atomization-based cutting fluid (ACF) application has been found to be an effective approach for cooling and lubrication in micromachining operations. In this study, an ACF spray system is developed for macro-scale turning of Ti–6Al–4V. The spray system is designed to minimize interaction between the fluid droplets, and the gas nozzle to control the divergence of the fluid droplets. Experiments are conducted to study the effect of five specific ACF spray parameters including fluid flow rate, spray distance, impingement angle, and type and pressure level of the droplet carrier gas on cutting forces, tool life, and chip characteristics. It has been observed that the combination of lower pressure (150 psi) air-mixed CO₂ with a higher flow rate (20 ml/min) and a larger spray distance (35 mm) produces a significantly longer tool life and broken chips. The results also reveal that the ACF spray system can extend tool life up to 40–50% over flood cooling.     

Incorporating stakeholder decision support needs into an integrated regional Earth system model

A new modeling effort exploring the opportunities, constraints, and interactions between mitigation and adaptation at regional scale is utilizing stakeholder engagement in an innovative approach to guide model development and demonstration, including uncertainty characterization, to effectively inform regional decision making. This project, the integrated Regional Earth System Model (iRESM), employs structured stakeholder interactions and literature reviews to identify the most relevant adaptation and mitigation alternatives and decision criteria for each regional application of the framework. The information is used to identify important model capabilities and to provide a focus for numerical experiments. This paper presents the stakeholder research results from the first iRESM pilot region. The pilot region includes the Great Lakes Basin in the Midwest portion of the United States as well as other contiguous states. This geographic area (14 states in total) permits cohesive modeling of hydrologic systems while also providing strong gradients in climate, demography, land cover/land use, and energy supply and demand. The results from the stakeholder research indicate that, for this region, iRESM should prioritize addressing adaptation alternatives in the water resources, urban infrastructure, and agriculture sectors, including water conservation, expanded water quality monitoring, altered reservoir releases, lowered water intakes, urban infrastructure upgrades, increased electric power reserves in urban areas, and land use management/crop selection changes. For mitigation in this region, the stakeholder research implies that iRESM should focus on policies affecting the penetration of renewable energy technologies, and the costs and effectiveness of energy efficiency, bioenergy production, wind energy, and carbon capture and sequestration.     

Modeling and interpretation of fiber orientation-based failure mechanisms in machining of carbon fiber-reinforced polymer composites

The development and implementation of a microstructure-based finite element model for the machining of carbon fiber-reinforced polymer composites is presented. A new approach to interfacial modeling is introduced where the material interface is modeled using continuum elements, allowing failure to take place in either tension or compression. The model is capable of describing the fiber failure mode occurring throughout the chip formation process. Characteristic fiber length in the chips, and machining forces for microstructures with fibers orientated at 0°, 45°, 90°, and 135° are examined. For model validation purposes, the model-based machining performance predictions are compared to the machining responses from a set of orthogonal machining experiments. A parametric study is presented that identifies a robust tool geometry, which minimizes the effects of fiber orientation and size on the machining forces.     

A review of myrmecophily in ant nest beetles (Coleoptera: Carabidae: Paussinae): linking early observations with recent findings

Myrmecophily provides various examples of how social structures can be overcome to exploit vast and well-protected resources. Ant nest beetles (Paussinae) are particularly well suited for ecological and evolutionary considerations in the context of association with ants because life habits within the subfamily range from free-living and predatory in basal taxa to obligatory myrmecophily in derived Paussini. Adult Paussini are accepted in the ant society, although parasitising the colony by preying on ant brood. Host species mainly belong to the ant families Myrmicinae and Formicinae, but at least several paussine genera are not host-specific. Morphological adaptations, such as special glands and associated tufts of hair (trichomes), characterise Paussini as typical myrmecophiles and lead to two different strategical types of body shape: while certain Paussini rely on the protective type with less exposed extremities, other genera access ant colonies using glandular secretions and trichomes (symphile type). We compare these adaptations with other taxonomic groups of insects by joining contemporary research and early sources and discuss the possibility of an attracting or appeasing effect of the secretion. Species that are ignored by their host ants might use chemical mimicry instead. Furthermore, vibrational signals may contribute to ant–beetle communication, and chemical signals have proven to play a role in host finding. The powerful defense chemistry of paussines as “bombardier beetles” is not used in contact with host ants. We attempt to trace the evolution of myrmecophily in paussines by reviewing important aspects of the association between paussine beetles and ants, i.e. morphological and potential chemical adaptations, life cycle, host specificity, alimentation, parasitism and sound production.

Evidence for a male-produced pheromone in <Emphasis Type="Italic">Tetropium fuscum</Emphasis> (F.) and <Emphasis Type="Italic">Tetropium cinnamopterum</Emphasis> (Kirby) (Coleoptera: Cerambycidae)

(E)-6,10-dimethyl-5,9-undecadien-2-ol (geranyl acetol), termed here fuscol, was identified as a male-produced pheromone emitted by Tetropium fuscum (F.) and Tetropium cinnamopterum Kirby. In field experiments, traps baited with synthetic fuscol alone were not significantly attractive, but the combination of fuscol plus host volatiles (a synthetic blend of monoterpenes plus ethanol) attracted significantly more male and female T. fuscum and female T. cinnamopterum than did host volatiles alone. This is the first homoterpenoid alcohol to be described in the Cerambycidae, and the first pheromone reported from the sub-family Spondylidinae.