Search

Research on canopy arthropods has progressed from species inventories to the study of their interactions and networks, enhancing our understanding of how hyper-diverse communities are maintained. Previous studies often focused on sampling individual tree species, individual trees or their parts. We argue that such selective sampling is not ideal when analyzing interaction network structure, and may lead to erroneous conclusions. We developed practical and reproducible sampling guidelines for the plot-based analysis of arthropod interaction networks in forest canopies. Our sampling protocol focused on insect herbivores (leaf-chewing insect larvae, miners and gallers) and non-flying invertebrate predators (spiders and ants). We quantitatively sampled the focal arthropods from felled trees, or from trees accessed by canopy cranes or cherry pickers in 53 0.1 ha forest plots in five biogeographic regions, comprising 6,280 trees in total. All three methods required a similar sampling effort and provided good foliage accessibility. Furthermore, we compared interaction networks derived from plot-based data to interaction networks derived from simulated non-plot-based data focusing either on common tree species or a representative selection of tree families. All types of non-plot-based data showed highly biased network structure towards higher connectance, higher web asymmetry, and higher nestedness temperature when compared with plot-based data. Furthermore, some types of non-plot-based data showed biased diversity of the associated herbivore species and specificity of their interactions. Plot-based sampling thus appears to be the most rigorous approach for reconstructing realistic, quantitative plant-arthropod interaction networks that are comparable across sites and regions. Studies of plant interactions have greatly benefited from a plot-based approach and we argue that studies of arthropod interactions would benefit in the same way. We conclude that plot-based studies on canopy arthropods would yield important insights into the processes of interaction network assembly and dynamics, which could be maximised via a coordinated network of plot-based study sites.

This study investigated the effects of balance exercise combined with whole-body vibration (WBV) on step performance and lower limb muscle activity during simulated forward falls using the tether-release method in older women. Twenty older women were assigned to either a WBV plus balance exercise group (WBV, n=10) or a balance exercise without vibration group (standard balance exercise group [STE], n=10). WBV performed weight-bearing exercises on a WBV platform combined with other balance exercises as a home program, whereas STE performed the same exercises without WBV. The exercise volume was equal in both intervention groups (3×/week for 12 weeks×30 min/session). The EMG and kinematic data of the stepping leg from the balance recovery step were examined before and after the intervention. While both groups extended step length during forward falls after the intervention, only WBV increased step velocity. EMG analysis of the balance recovery step showed that both groups increased peak EMG of knee flexor and extensor muscles after intervention. After intervention, WBV increased peak EMG of the plantar flexors, which are used to exert the push-off forces just before the leg swing. Balance exercise in older women resulted in significant improvements in the balance recovery step after a simulated forward fall. WBV also had the additional benefit of improved step velocity, which was reflected in increased activity of the plantar flexors in the stepping leg.

The effects of ultrasonic vibration on injection molding were investigated. An ultrasonic injection molding (UIM) machine in which the mold resonated under ultrasonic vibration was developed. The resonance in the mold occurred at n wavelengths, where n=0.5N and N is a positive integer. A transducer was placed on the movable mold through a directional converter of vibration. The fluidity of the molding materials and the molecular orientation of products were evaluated by the UIM machine. This evaluation allowed the improvement of the apparent fluidity of the molding materials compared to the case without ultrasonic vibration. Consequently, the molecular orientation caused by the flow was decreased. Wall slip was observed between the resin and wall surface with ultrasonic vibration in flow visualization experiments. It was found that the fluidity was improved by the action of sound pressure and the reduction of apparent friction between the wall surface in a cavity and the molding material by ultrasonic waves.

This study aimed at comparing the patterns of muscle activation used in stepping to regain balance during a forward fall between subjects with and without a history of falling and at identifying the causes of functional deficits in recovery stepping. Elderly women with and without a history of falling (fallers: n = 12, mean age ± SD = 82.8 ± 4.5 years; non-fallers: n = 17, age = 81.4 ± 3.4 years) participated in the study. The subjects were suspended in a forward-leaning position by a lean-control cable with a load of 15 % of body weight and instructed to regain standing balance upon release by taking a single step forward. Electromyography (EMG) data were obtained from five lower extremity muscles on the stepping side, and the muscle activation patterns were compared between fallers and non-fallers. Fallers had a shorter step length and slower step velocity than non-fallers. The EMG time-to-peak for the gastrocnemius muscle, which provides push-off prior to foot lift-off, was slower for fallers than for non-fallers, whereas the EMG onset times of the biceps femoris and gastrocnemius muscles were similar between the groups. The fallers exhibited significantly delayed muscle deactivation of the upper leg and increased co-contraction between the rectus femoris and biceps femoris during the stepping phase than did the non-fallers. These findings suggest that the muscle activation pattern during the regain balance may reflect an inability to step forward rapidly in elderly women with a history of falls.