Search

Background and aimsPendulous flowers (due to a flexible pedicel) are a common, convergent trait of hummingbird-pollinated flowers. However, the role of flexible pedicels remains uncertain despite several functional hypotheses. Here we present and test the 'lever action hypothesis': flexible pedicels allow pendulous flowers to move upwards from all sides, pushing the stigma and anthers against the underside of the feeding hummingbird regardless of which nectary is being visited.MethodsTo test whether this lever action increased pollination success, we wired emasculated flowers of serpentine columbine, Aquilegia eximia, to prevent levering and compared pollination success of immobilized flowers with emasculated unwired and wire controls.Key resultsSeed set was significantly lower in wire-immobilized flowers than unwired control and wire control flowers. Video analysis of visits to wire-immobilized and unwired flowers demonstrated that birds contacted the stigmas and anthers of immobilized flowers less often than those of flowers with flexible pedicels.ConclusionsWe conclude that flexible pedicels permit the levering of reproductive structures onto a hovering bird. Hummingbirds, as uniquely large, hovering pollinators, differ from flies or bees which are too small to cause levering of flowers while hovering. Thus, flexible pedicels may be an adaptation to hummingbird pollination, in particular due to hummingbird size. We further speculate that this mechanism is effective only in radially symmetric flowers; in contrast, zygomorphic hummingbird-pollinated flowers are usually more or less horizontally oriented rather than having pendulous flowers and flexible pedicels.

Head controls provide an alternative means of computer access. This study determined whether neck movement limitations are associated with reduced performance with such head controls. This study also identified features of the cursor movement path that could aid in assessing computer access limitations. Fifteen subjects without disabilities and ten subjects with disabilities received neck range of motion evaluations and performed computer exercises using head controls. Reduced neck range of motion was correlated with reduced accuracy (R2 = 93.5%) and speed (R2 = 79.5%) in icon selection. A model was developed with the use of cursor positioning time and number of velocity peaks to identify when a person was having difficulty with target acquisition (kappa = 0.81). Models such as this may allow head controls to adapt to a user's needs, accommodating difficulties resulting from neck range of motion limitations. [ABSTRACT FROM AUTHOR]

Interactions between plants and herbivores are central in most ecosystems, but their strength is highly variable. The amount of variability within a system is thought to influence most aspects of plant-herbivore biology, from ecological stability to plant defense evolution. Our understanding of what influences variability, however, is limited by sparse data. We collected standardized surveys of herbivory for 503 plant species at 790 sites across 116° of latitude. With these data, we show that within-population variability in herbivory increases with latitude, decreases with plant size, and is phylogenetically structured. Differences in the magnitude of variability are thus central to how plant-herbivore biology varies across macroscale gradients. We argue that increased focus on interaction variability will advance understanding of patterns of life on Earth.

Many seeds are consumed by granivores despite numerous adaptations to prevent detection or exploitation. The environment can influence the efficacy of these defensive traits. Understanding the mechanisms by which environmental factors modify defensive efficacy is important for understanding spatial patterns of granivory and seed recruitment. Seed mucilage is a sticky coating that binds imbibed seeds to substrates; this attachment has been demonstrated to lessen exploitation by granivores. Seed mucilage as a defense has been recognized for decades, though rarely studied. Here, we investigated whether the environment alters this seed defense by addressing two questions: (1) Does substrate particle size affect attachment strength? (2) Does a change in particle size lead to changes in granivore-related mortality? In the field experiment, ants removed more seeds from finer substrates than their coarser counterparts. Across that same grit range, seeds took less force to dislodge when mucilage-bound to fine sandpaper; however, an investigation across a wider range of grits demonstrated nonlinearities occurred for many species, probably due to structural and chemical mucilage properties. Small differences in substrate grit lead to differential mortality in mucilaginous seeds due to alterations in attachment strength, suggesting that the defensive efficacy of this trait differs across the landscape. This work paves the way for a more integrative look at mucilaginous seeds. Seed mucilage is a widespread trait that is easily studied and has important demographic implications. It represents an ideal system to examine dispersal, germination, and granivory to gain a more holistic view of seed ecology., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Compare the perioperative outcomes and disease-free survival between minimally invasive and open surgery in women with stage I-II high-risk endometrial cancer., Methods: A retrospective, cohort study was performed involving twenty-four centers from Argentina. Patients with grade 3 endometrioid, serous, clear cell, undifferentiated carcinoma or carcinosarcoma who underwent hysterectomy, bilateral salpingo-oophorectomy, and staging between January 2010-2018 were included. Cox hazard regression analysis and Kaplan-Meier curves evaluated the association of surgical technique with survival., Results: Of 343 eligible patients, 214 (62 %) underwent open surgery and 129 (38 %) underwent laparoscopic surgery. No significant differences were seen between the two groups with respect to greater or equal grade III Clavien-Dindo postoperative complications (11 % in the open surgery group vs 9 % minimally invasive surgery group; P = 0.34) Minimally invasive surgery was not associated with worse disease-free survival at four years (79.14 % [95 % CI 69.42- 86.08] vs 78.80 % [95 % CI 70.61-84.96]), (p = 0.25), even after creating a Cox proportional model (hazard ratio [HR] 1.08 95 % CI 0.63-1.84); (p = 0.76)., Conclusion: There was no difference between postoperative complications nor oncologic outcomes comparing minimally invasive and open surgery among patients with high-risk endometrial cancer., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

Many herbivorous insects die of pathogen infections, though the role of plant traits in promoting the persistence of these pathogens as an indirect interaction is poorly understood. We tested whether winter leaf retention of bush lupines (Lupinus arboreus) promotes the persistence of a nucleopolyhedroviruses, thereby increasing the infection risk of caterpillars (Arctia virginalis) feeding on the foliage during spring. We also investigated whether winter leaf retention reduces viral exposure of younger caterpillars that live on the ground, as leaf retention prevents contaminated leaves from reaching the ground. We surveyed winter leaf retention of 248 lupine bush canopies across twelve sites and examined how it related to caterpillar infection risk, herbivory, and inflorescence density. We also manipulated the amount of lupine litter available to young caterpillars in a feeding experiment to emulate litterfall exposure in the field. Greater retention of contaminated leaves from the previous season increased infection rates of caterpillars in early spring. Higher infection rates reduced herbivory and increased plant inflorescence density by summer. Young caterpillars exposed to less litterfall were more likely to starve to death but less likely to die from infection, further suggesting foliage mediated exposure to viruses. We speculate that longer leaf life span may be an unrecognized trait that indirectly mediates top-down control of herbivores by facilitating epizootics., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background and Aims: Seed mucilage is a common and highly diverse trait shared among thousands of angiosperm species. While it has long been recognized that mucilage allows seeds to anchor to substrates (antitelechory), resisting abiotic and biotic dislodgement, we still lack a mechanistic understanding of this process., Methods: We propose a mechanistic model of how mucilage affects substrate anchorage and fluid resistance, ultimately contributing to dislodgement resistance. To test this model, we subjected mucilaginous seeds of 52 species, varying in eight measured seed traits, to 7 d of continuous water flow at a range of dislodgement potentials., Key Results: Supporting our model, mucilage mass increased the force necessary to dislodge both dry and wet seeds; our measurement of the dislodgement force of dry mucilage explained time to dislodgement well. The effect size was remarkably large; increasing the standardized mucilage mass by 1 s.d. resulted in a 280-fold increase in the time to dislodgement. Fluid resistance was largely dependent on the speed of water flow and the seed's modified drag coefficient, but not seed traits. Neither mucilage expansion speed nor mucilage decay rate explained dislodgement potential well., Conclusions: Our results suggest that the degree of anchorage to a substrate, measured with a simple dislodgement force assay, is highly predictive of mucilaginous seed retention in highly erosive environments. In contrast, we found that other seed and mucilage traits are of lesser importance to anchorage., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Incompletely reproductively isolated species often segregate into different microhabitats, even when they are able to survive and reproduce in both habitats. Longer term evolutionary factors may contribute to this lack of cross-habitat persistence. When reproductive interference reduces immigrant fitness, assortative mating, including self-fertilization, increases immigrants' fitness in a single generation, but longer term, inbreeding depression may reduce the chance of population persistence. Two California monkeyflower species repeatedly segregate into drier and wetter areas in their zone of sympatry. To test whether inbreeding depression may contribute to the maintenance of this segregation pattern, we transplanted outbred and successively inbred Mimulus guttatus and Mimulus nudatus into their native habitats and heterospecific habitats. We measured germination, survival, and seed set and found that recurrent selfing reduced all aspects of fitness in both species, most strongly in foreign habitats. A simulation model, parameterized from the transplant experiment, found that inbreeding reduced fitness to such an extent that sequentially inbred populations of either species would be unable to persist in heterospecific-occupied habitats in the absence of continued gene flow. These results demonstrate that individual immigrants are unlikely to form persistent populations and thus, inbreeding depression contributes to the absence of fine-scale coexistence in this species pair., (© 2021 The Authors. Evolution © 2021 The Society for the Study of Evolution.)

Seed mucilage, a coating on seeds or fruit that becomes slimy and sticky when wet, has evolved convergently many times across plants. One common consequence of having seed mucilage is that sand and dirt particles stick to wet seeds and remain tightly bound to the seed surface after the mucilage dries. Here, we test the hypothesis that a mucilage-bound sand coating protects the seed from seed predators; either as a physical barrier or by reducing apparency of the seed (i.e., camouflage). We experimentally manipulated the sand coating on seeds of 53 plant species of 13 families and assayed the defensive benefit of the sand coating in feeding "depots" near harvester ant nests in California's Central Valley. Consistent with a defensive function, sand coating reduced ant predation on seeds in 48 of the 53 species examined. To test whether this striking benefit was due to reduced apparency, we conducted an addition experiment using flax seeds in which we factorially manipulated the color of both the background substrate and the sand coating, creating visually apparent and unapparent seeds. Our results did not support the reduced apparency hypothesis; seeds coated in background-matched sand were removed at the same rate as seeds coated in unmatched sand. The defensive benefit of a sand coating was not well-predicted by seed mass, entrapped sand mass, or sand mass scaled by seed mass. Together, our results demonstrate that seed mucilage is a phylogenetically widespread and effective seed defensive trait and point to the physical barrier, not reduced apparency, as a mechanism., (© 2019 by the Ecological Society of America.)

Premise of the Study: Wildfire changes the demography, morphology, and behavior of plants, and may alter the pollinator community. Such trait changes may drastically alter the outcome of pollination mutualisms on plants; however, the direct role of fire on these mutualisms is poorly known., Methods: Following a pair of fires in the northern California coast range chaparral, we censused floral visitor communities of Trichostema laxum (Lamiaceae), quantified visiting bee behavior, and estimated outcrossing rates using a widespread Mendelian recessive floral polymorphism across a matrix of populations in burned and unburned sites. We also compared pre- and postfire floral visitation in two populations., Results: Outcrossing rates were significantly lower in burned areas; however, our data suggest that the much larger size of plants in burned areas, not burn status itself, drove this pattern. Large-bodied bees dominated floral visitor communities after fire, likely recruiting to the abundant postfire floral resources. These bees visited more flowers per plant than did the smaller bees prevalent before fire and in unburned areas, likely increasing selfing through geitonogamy (within-plant pollination), an effect made possible by the far larger size of plants in burned areas., Conclusions: Outcrossing rates dropped substantially after wildfires because of changes in the pollinators, plant display size, and their interactions. Reductions in outcrossing following fire may have important implications for population resilience and evolution in a changing climate with more frequent fires., (© 2018 Botanical Society of America.)

Few species of insect herbivores are highly polyphagous, but those few species are disproportionately ecologically and economically important and include many of the most destructive crop pests. Common correlates of extreme polyphagy across insects include the related behaviors of cannibalism and omnivory, though any functional consequences of these behaviors on the host range are unknown. I hypothesized that omnivory may allow these insects to exploit marginal hosts successfully (an expansion of realized niche). Using the polyphagous pest caterpillar, Heliothis virescens, I tested the polyphagy by omnivory hypothesis using ten host plants of varying suitability and small quantities of insect carrion. Caterpillars which were allowed omnivory had increased performance on lower-quality hosts; this treatment raised survival, growth rate, and pupal mass over controls on a strictly plant diet. Omnivory allowed successful development on two plants that caterpillars could not exploit alone a potential niche expansion. This effect was limited, however: (1) on high-quality hosts, omnivory did not improve performance, and (2) omnivory on poor hosts did not increase growth rate or pupal mass to levels matching the most suitable hosts and it could not permit exploitation of a completely unpalatable plant. Omnivory may therefore be an important (and overlooked) factor in determining the success of generalist insect herbivores in a variety of ecological settings.

Plants produce and utilize a great diversity of chemicals for a variety of physiological and ecological purposes. Many of these chemicals defend plants against herbivores, pathogens and competitors. The location of these chemicals varies within the plant, some are located entirely within plant tissues, others exist in the air- (or water-) space around plants, and still others are secreted onto plant surfaces as exudates. I argue herein that the location of a given defensive chemical has profound implications for its ecological function; specifically, I focus on the characteristics of chemical defences secreted onto plant surfaces. Drawing from a broad literature encompassing ecology, evolution, taxonomy and physiology, I found that these external chemical defences (ECDs) are common and widespread in plants and algae; hundreds of examples have been detailed, yet they are not delineated as a separate class from internal chemical defences (ICDs). I propose a novel typology for ECDs and, using existing literature, explore the ecological consequences of the hypothesized unique characteristics of ECDs. The axis of total or proportional investment in ECDs versus ICDs should be considered as one axis of investment by a plant, in the same way as quantitative versus qualitative chemical defences or induced versus constitutive defences is considered. The ease of manipulating ECDs in many plant systems presents a powerful tool to help test plant defence theory (e.g. optimal defence). The framework outlined here integrates various disciplines of botany and ecology and suggests a need for further examinations of exudates in a variety of contexts, as well as recognition of the effects of within-plant localization of defences., (© 2015 Cambridge Philosophical Society.)

A novel mobile health platform, Interactive Mobile Health and Rehabilitation (iMHere), is being developed to support wellness and self-management among people with chronic disabilities. The iMHere system currently includes a smartphone app with six modules for use by persons with disabilities and a web portal for use by medical and rehabilitation professionals or other support personnel. Our initial clinical research applying use of this system provides insight into the feasibility of employing iMHere in the development of self-management skills in young adults (ages 18-40 years) with spina bifida (SB) (Dicianno, Fairman, et al., 2015). This article describes the iterative design of the iMHere system including usability testing of both the app modules and clinician portal. Our pilot population of persons with SB fostered the creation of a system appropriate for people with a wide variety of functional abilities and needs. As a result, the system is appropriate for use by persons with various disabilities and chronic conditions, not only SB. In addition, the diversity of professionals and support personnel involved in the care of persons with SB also enabled the design and implementation of the iMHere system to meet the needs of an interdisciplinary team of providers who treat various conditions. The iMHere system has the potential to foster communication and collaboration among members of an interdisciplinary healthcare team, including individuals with chronic conditions and disabilities, for a client-centered approach to support self-management skills.

Sand entrapment on plant surfaces, termed psammophory or sand armor, is a phylogenetically and geographically widespread trait. The functional significance of this phenomenon has been poorly investigated. Sand and soil are nonnutritive and difficult for herbivores to process, as well as visually identical to the background. We experimentally investigated whether this sand coating physically protected the plant from herbivores or increased crypsis (e.g., decreased apparency to herbivores). We tested the former hypothesis by removing entrapped sand from stems, petioles, and leaves of the sand verbena Abronia latifolia and by supplementing natural sand levels in the honeyscented pincushion plant Navarretia mellita. Consistent with a physical defensive function, leaves with sand present or supplemented suffered less chewing herbivory than those with sand removed or left as is. To test a possible crypsis effect, we coated some sand verbena stems with green sand, matching the stem color, as well as others with brown sand to match the background color. Both suffered less chewing herbivory than controls with no sand and herbivory did not significantly differ between the colors, suggesting crypsis was not the driving resistance mechanism. Strong tests of plant apparency are rare; this experimental approach may be possible in other systems and represents one of few manipulative tests of this long-standing hypothesis.

Telerehabilitation (TR) services for assistive technology evaluation and training have the potential to reduce travel demands for consumers and assistive technology professionals while allowing evaluation in more familiar, salient environments for the consumer. Sixty-five consumers received TR services for augmentative and alternative communication or alternative computer access, and consumer satisfaction was compared with twenty-eight consumers who received exclusively in-person services. TR recipients rated their TR services at a median of 6 on a 6-point Likert scale TR satisfaction questionnaire, although individual responses did indicate room for improvement in the technology. Overall satisfaction with AT services was rated highly by both in-person (100% satisfaction) and TR (99% satisfaction) service recipients.

Many plants provide predatory arthropods with food or shelter. Glandular trichomes entrap insects and may provision predators with insect carrion, though it has not been clear whether this putative benefit functions with natural amounts of carrion, whether plants actively attract insect "tourists," and how common this provisioning system is. We tested the hypothesis that a sticky columbine (Aquilegia eximia: Ranunculaceae) attracts passerby arthropods (a siren song leading them to their demise); that these entrapped arthropods increased predators on the plant; and that these predators reduced damage to the plant. Sticky traps baited with columbine peduncles entrapped more arthropod carrion than unbaited control traps. Predator abundance correlated positively with carrion abundance observationally, and experimental removal of carrion reduced predator numbers. Experimental removal of carrion also increased damage to reproductive structures, likely due to reductions in predator numbers. This indirect defense may be common; we compiled a list of insect-trapping sticky plants that includes over 110 genera in 49 families, suggesting a widespread convergence of this trait, even in non-carnivorous plants. The ubiquity of this trait combined with these experiments suggest that carrion entrapment should be viewed as a common and active process mediated by the plant for indirect defense.

Trichomes on leaves and stems of certain chenopods (Chenopodiaceae) are modified with a greatly enlarged apical cell (a salt bladder), containing a huge central vacuole. These structures may aid in the extreme salt tolerance of many species by concentrating salts in the vacuole. Bladders eventually burst, covering the leaf in residue of bladder membranes and solid precipitates. The presence of this system in non-halophytic species suggests additional functions. I tested the novel hypothesis that these bladders have a defensive function against insect herbivores using choice, no choice, and field tests. Generalist insect herbivores preferred to feed on leaves without salt bladders in choice tests. In no choice tests, herbivores consumed less leaf matter with bladders. In a field test, leaves from which I had removed bladders suffered greater herbivory than adjacent leaves with bladders. Solutions containing bladders added to otherwise preferred leaves deterred herbivores, suggesting a water-soluble chemical component to the defense. This bladder system has a defensive function in at least four genera of chenopods. Salt bladders may be a structural defense, like spines or domatia, but also have a chemical defense component.

Nonambulatory, visually impaired individuals mostly rely on caregivers for their day-to-day mobility needs. The Drive-Safe System (DSS) is a modular, semiautonomous smart wheelchair system aimed at providing independent mobility to people with visual and mobility impairments. In this project, clinical evaluation of the DSS was performed in a controlled laboratory setting with individuals who have visual impairment but no mobility impairment. Their performance using DSS was compared with their performance using a standard cane for navigation assistance. Participants rated their subjective appraisal of the DSS by using the National Aeronautics and Space Administration-Task Load Index inventory. DSS significantly reduced the number and severity of collisions compared with using a cane alone and without increasing the time required to complete the task. Users rated DSS favorably; they experienced less physical demand when using the DSS, but did not feel any difference in perceived effort, mental demand, and level of frustration when using the DSS alone or along with a cane in comparison with using a cane alone. These findings suggest that the DSS can be a safe, reliable, and easy-to-learn and operate independent mobility solution for visually impaired wheelchair users.

The Drive-Safe System (DSS) is a collision-avoidance system for power wheelchairs designed to support people with mobility impairments who also have visual, upper-limb, or cognitive impairments. The DSS uses a distributed approach to provide an add-on, shared-control, navigation-assistance solution. In this project, the DSS was tested for engineering goals such as sensor coverage, maximum safe speed, maximum detection distance, and power consumption while the wheelchair was stationary or driven by an investigator. Results indicate that the DSS provided uniform, reliable sensor coverage around the wheelchair; detected obstacles as small as 3.2 mm at distances of at least 1.6 m; and attained a maximum safe speed of 4.2 km/h. The DSS can drive reliably as close as 15.2 cm from a wall, traverse doorways as narrow as 81.3 cm without interrupting forward movement, and reduce wheelchair battery life by only 3%. These results have implications for a practical system to support safe, independent mobility for veterans who acquire multiple disabilities during Active Duty or later in life. These tests indicate that a system utilizing relatively low cost ultrasound, infrared, and force sensors can effectively detect obstacles in the vicinity of a wheelchair.

Purpose: Software was developed which makes recommendations regarding configuration of a computer pointing device, such as a mouse, to accommodate a person's physical impairment. Specifically, a software agent automatically recommends a setting for the computer's control-display gain based on observations of a user's performance in a target selection task., Method: The software agent makes its recommendations based on available adjustment settings in the existing operating system. The agent was evaluated in studies with 12 participants who have motor impairments., Results: The agent-selected gain was not associated with significant improvements in selection time or error-free performance compared with the operating system's default gain. Across participants and trials, gain did not have a significant effect on selection time except at the lowest gain settings tested. However, two participants did have notable and consistent improvement in selection time and error-free performance using the agent-selected gain; gain across trials had a significant effect on number of target entries and number of submovements; and a post-hoc analysis indicated improved target selection time when varying both target size and control-display gain., Conclusion: These observations provide possible avenues for future work, although the current study indicates that changes to control-display gain, alone, are unlikely to offer improvements in speed or accuracy for the general population of people with motor impairments.

Background: In long-term care environments, residents who have severe mobility deficits are typically transported by having another person push the individual in a manual wheelchair. This practice is inefficient and encourages staff to hurry to complete the process, thereby setting the stage for unsafe practices. Furthermore, the time involved in assembling multiple individuals with disabilities often deters their participation in group activities., Methods: The Wheelchair Convoy System (WCS) is being developed to allow a single caregiver to move multiple individuals without removing them from their wheelchairs. The WCS will consist of a processor, and a flexible cord linking each wheelchair to the wheelchair in front of it. A Participatory Design approach - in which several iterations of design, fabrication and evaluation are used to elicit feedback from users - was used., Results: An iterative cycle of development and evaluation was followed through five prototypes of the device. The third and fourth prototypes were evaluated in unmanned field trials at J. Iverson Riddle Development Center. The prototypes were used to form a convoy of three wheelchairs that successfully completed a series of navigation tasks., Conclusion: A Participatory Design approach to the project allowed the design of the WCS to quickly evolve towards a viable solution. The design that emerged by the end of the fifth development cycle bore little resemblance to the initial design, but successfully met the project's design criteria. Additional development and testing is planned to further refine the system.

Head-operated computer controls provide an alternative means of computer access for people with disabilities who are unable to use a standard mouse. However, a person's disability may limit his or her neck movements as well as upper extremity movements. Software was developed which automatically adjusts the interface sensitivity to the needs of a particular user. This adaptive software was evaluated in two stages. First, 16 novice head-control users with spinal-cord injury or multiple sclerosis used head controls with and without the adaptive software. The adaptive software was associated with increased speed in standardized icon selection exercises (p < 0.05). A small increase in accuracy was also observed. In addition, five current head-control users evaluated the software in a real-world setting. One of these five subjects perceived an improvement in comparison to his current head-control system.