Novel anterior coracoglenoid line utilizing magnetic resonance imaging (MRI) corresponds with critical glenoid bone loss.

OBJECTIVE: Glenoid bone loss is estimated using a best-fit circle method and requires software tools that may not be available. Our hypothesis is that a vertical reference line drawn parallel to the long axis of the glenoid and passing through the inflection point of the coracoid and glenoid will represent a demarcation line of approximately 20% of the glenoid. Our aim is to establish a more efficient method to estimate a surgical threshold for glenoid insufficiency. METHODS: Fifty patients with normal glenoid anatomy were randomly chosen from an orthopedic surgeon's database. Two orthopedic surgeons utilized T1-weighted sagittal MRIs and the coracoglenoid line technique to determine the percentage of bony glenoid anterior to vertical line. Two musculoskeletal radiologists measured the same 50 glenoids using the circle technique. Differences were determined using dependent t test. Reliability was compared using interclass correlation coefficient and Kappa. Validity was compared using Pearson correlation coefficient. RESULTS: Mean surface area of the glenoid anterior to the vertical line was on average 21.69% ± 3.12%. Surface area of the glenoid using the circle method was on average 20.86% ± 2.29%. Inter-rater reliability of the circle method was 0.553 (fair). Inter-rater reliability of the vertical line technique was 0.83 (excellent). There was a linear relationship between circle and vertical line measurements, r = 0.704 (moderate to high). CONCLUSION: The coracoglenoid line appears to represent a line of demarcation of approximately 21% of glenoid bone anterior to the coracoglenoid line. Our technique was found to be reliable, valid, and accurate.

Habitat Suitability and Establishment Limitations of a Problematic Liana.

The US native liana, poison ivy (Toxicodendron radicans), responsible for contact dermatitis in humans, is a competitive weed with great potential for expansion in disturbed habitats. To facilitate a better understanding of this threat, we sought to evaluate habitat suitability, population demography, and biotic interactions of poison ivy, using a series of complementary field studies in the two habitats where it most commonly occurs-forest interiors and edges. Of the 2500 seeds planted across both habitats, poison ivy initially colonized forest interiors (32% emergence) at a higher rate than edge habitats (16.5% emergence). However, forest interior seedlings were less likely to survive (interior n = 3; edge n = 15), which might be attributed to herbivore pressure when the seedlings were smaller in the less competitive forest interior. Once established, the poison ivy seedlings appeared to be more tolerant of herbivory, except that of large grazers such as deer. The early life stage of seedling emergence, survival, and establishment are critical in poison ivy success, with biotic pressure, especially from plant competition and deer, limiting recruitment. A suitable habitat of this expanding native liana would increase with increasing forest fragmentation, but might be buffered by the expanding deer population.

Poison ivy hairy root cultures enable a stable transformation system suitable for detailed investigation of urushiol metabolism.

Poison ivy (Toxicodendron radicans) is best known for causing exasperating allergenic delayed-contact dermatitis symptoms that last for weeks on persons who have contacted the plant. Urushiols are alkylcatechols produced by poison ivy responsible for causing this dermatitis. While urushiol chemical structures are well known, the metabolic intermediates and genes responsible for their biosynthesis have not been experimentally validated. A molecular genetic characterization of urushiol biosynthesis in poison ivy will require stable genetic transformation and subsequent regeneration of organs that retain the capacity synthesize urushiol. To this end, Agrobacterium rhizogenes was used to generate hormone-independent poison ivy hairy root cultures. Optimal conditions for hairy root formation were skotomorphic poison ivy hypocotyls prick-inoculated with A. rhizogenes, and preferential propagation of cultures with an atypical clumpy hairy root growth habit. The origin of the poison ivy accession used for A. rhizogenes prick-inoculation did not affect the initial formation of calli/hairy root primordia, but rather significantly influenced the establishment of long-term hormone-independent hairy root growth. A. rhizogenes harboring a recombinant T-DNA binary plasmid with an intron-containing Firefly Luciferase gene produced stable transgenic hairy root lines expressing luciferase activity at high frequency. Poison ivy hairy root lines produced significantly lower steady-state urushiol levels relative to wild-type roots, but higher urushiol levels than a poison ivy undifferentiated callus line with undetectable urushiol levels, suggesting that urushiol biosynthesis requires intact poison ivy organs. The lower urushiol levels in poison ivy hairy root lines facilitated the first identification of anacardic acid metabolites initially in hairy roots, and subsequently in wild-type roots as well. This study establishes a transformation hairy root regeneration protocol for poison ivy that can serve as a platform for future reverse-genetic studies of urushiol biosynthesis in poison ivy hairy roots.

Accession-Level Differentiation of Urushiol Levels, and Identification of Cardanols in Nascent Emerged Poison Ivy Seedlings.

Poison ivy (Toxicodendron radicans (L.) Kuntze) shows accession-level differentiation in a variety of morphometric traits, suggesting local adaptation. To investigate whether the presumed defense compound urushiol also demonstrates accession-level accumulation differences, in vitro nascent germinated poison ivy seedlings from geographically isolated populations were germinated in vitro and then assayed for known urushiol congener accumulation levels. Significant accession-level differences in the accumulation levels of total C15- and C17-, total C15-, total C17-, specific C15 congeners, and specific C17 congeners of urushiol were identified. In addition, hereto novel C15- and C17-urushiol isomers were identified as well. Cardanols are assumed to be the penultimate metabolites giving rise to urushiols, but this assumption was not previously empirically validated. C15-cardanol congeners and isomers corresponding to expected substrates needed to produce the observed C15-urushiol congeners and isomers were identified in the same poison ivy seedling extracts. Total C15-cardanol and C15-cardanol congeners also showed significant accession-level differences. Based on the observed C15-cardanol congeners in poison ivy, the penultimate step in urushiol biosynthesis was proposed to be a cardanol-specific hydroxylase activity.

Invasive plants negatively impact native, but not exotic, animals.

Despite our growing understanding of the impacts of invasive plants on ecosystem structure and function, important gaps remain, including whether native and exotic species respond differently to plant invasion. This would elucidate basic ecological interactions and inform management. We performed a meta-analytic review of the effects of invasive plants on native and exotic resident animals. We found that invasive plants reduced the abundance of native, but not exotic, animals. This varied by animal phyla, with invasive plants reducing the abundance of native annelids and chordates, but not mollusks or arthropods. We found dissimilar impacts among "wet" and "dry" ecosystems, but not among animal trophic levels. Additionally, the impact of invasive plants increased over time, but this did not vary with animal nativity. Our review found that no studies considered resident nativity differences, and most did not identify animals to species. We call for more rigorous studies of invaded community impacts across taxa, and most importantly, explicit consideration of resident biogeographic origin. We provide an important first insight into how native and exotic species respond differently to invasion, the consequences of which may facilitate cascading trophic disruptions further exacerbating global change consequences to ecosystem structure and function.

Patient-Reported Allergies Predict Worse Outcomes After Hip and Knee Arthroplasty: Results From a Prospective Cohort Study.

BACKGROUND: Retrospective analyses have demonstrated correlation between patient-reported allergies and negative outcomes after total joint arthroplasty. We sought to validate these observations in a prospective cohort. METHODS: One hundred forty-four patients undergoing total hip arthroplasty and 302 patients undergoing total knee arthroplasty were prospectively enrolled. Preoperatively, patients listed their allergies and completed the Medical Outcomes Study Short Form 36 (SF-36) and the Charlson Comorbidity Index (CCI) Questionnaire. At a mean of 17 months (range 12-25 months) postoperatively, SF-36, CCI, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were obtained by telephone survey. Regression analysis was used to determine the strength of correlation between patient age, comorbidity burden, and number of allergies and outcome measurements. RESULTS: In 446 patients, 273 reported at least 1 allergy. The number of allergies reported ranged from 0 to 33. Penicillin or its derivative was the most frequently reported allergy followed by sulfa, environmental allergen, and narcotic pain medication. Patients reporting at least 1 allergy had a significantly lower postoperative SF-36 Physical Component Score compared to those reporting no allergies (51.3 vs 49.4, P = .01). The SF-36 postoperative Mental Component Score was no different between groups. Multivariate regression analysis showed that age and patient reported allergies, but not comorbidities, were independently associated with worse postoperative SF-36 Physical Component Summary (PCS) and WOMAC score. Patients with allergies experienced the same improvement in SF-36 PCS as those without an allergy. Comorbidities did not correlate with patient-reported function postoperatively. CONCLUSION: Patients who report allergies have lower postoperative outcome scores but may experience the same increment in improvement after total joint arthroplasty.

The physical sacrifice of thinking: Investigating the relationship between thinking and physical activity in everyday life.

Physical activity level is an important contributor to overall human health and obesity. Research has shown that humans possess a number of traits that influence their physical activity level including social cognition. We examined whether the trait of "need for cognition" was associated with daily physical activity levels. We recruited individuals who were high or low in need for cognition and measured their physical activity level in 30-second epochs over a 1-week period. The overall findings showed that low-need-for-cognition individuals were more physically active, but this difference was most pronounced during the 5-day work week and lessened during the weekend.

Objects influence the shape of remembered views: examining global and local aspects of boundary extension.

Boundary extension is a constructive memory error for views of scenes in which viewx tendto be remembered as more spatially expansive than they appeared. In seven experiments xwe examinedwhether local differences in boundary extension within views might exist by presenting par ticipants ith overhead views of single, elongated objects or object pairs on textured ground surfaces i:n whichobjects were oriented either vertically or horizontally. Memory for views' spatial expanse xwas testedwith either a view-recognition test or a border-adjustment test in which participants could ad just thespatial expanse of a test view using the computer's mouse. The border-adjustment test was uused tossess local boundary extension (primarily); the view-recognition test was used to assess paparticipants'emories for the overall spatial expanse of views (ie global boundary extension). Across exexperiments,n the border-adjustment tests specifically, participants showed more spatial expanse along the obobject'songer axis, in some cases restricting the view along the object's shorter axis. In addition, the rerecognition-t data revealed greater boundary extension for views with vertically oriented objects than for x.iviewsth horizontally oriented objects. Taken together, the results suggest that objects in scene x iviews canfect both local and global aspects of memory for spatial expanse of scene views.

Fixating picture boundaries does not eliminate boundary extension: implications for scene representation.

Observers frequently remember seeing more of a scene than was shown (boundary extension). Does this reflect a lack of eye fixations to the boundary region? Single-object photographs were presented for 14-15 s each. Main objects were either whole or slightly cropped by one boundary, creating a salient marker of boundary placement. All participants expected a memory test, but only half were informed that boundary memory would be tested. Participants in both conditions made multiple fixations to the boundary region and the cropped region during study. Demonstrating the importance of these regions, test-informed participants fixated them sooner, longer, and more frequently. Boundary ratings (Experiment 1) and border adjustment tasks (Experiments 2-4) revealed boundary extension in both conditions. The error was reduced, but not eliminated, in the test-informed condition. Surprisingly, test knowledge and multiple fixations to the salient cropped region, during study and at test, were insufficient to overcome boundary extension on the cropped side. Results are discussed within a traditional visual-centric framework versus a multisource model of scene perception.

New Evidence for Strategic Differences between Static and Dynamic Search Tasks: An Individual Observer Analysis of Eye Movements.

Two experiments are reported that further explore the processes underlying dynamic search. In Experiment 1, observers' oculomotor behavior was monitored while they searched for a randomly oriented T among oriented L distractors under static and dynamic viewing conditions. Despite similar search slopes, eye movements were less frequent and more spatially constrained under dynamic viewing relative to static, with misses also increasing more with target eccentricity in the dynamic condition. These patterns suggest that dynamic search involves a form of sit-and-wait strategy in which search is restricted to a small group of items surrounding fixation. To evaluate this interpretation, we developed a computational model of a sit-and-wait process hypothesized to underlie dynamic search. In Experiment 2 we tested this model by varying fixation position in the display and found that display positions optimized for a sit-and-wait strategy resulted in higher d' values relative to a less optimal location. We conclude that different strategies, and therefore underlying processes, are used to search static and dynamic displays.

Do object refixations during scene viewing indicate rehearsal in visual working memory?

Do refixations serve a rehearsal function in visual working memory (VWM)? We analyzed refixations from observers freely viewing multiobject scenes. An eyetracker was used to limit the viewing of a scene to a specified number of objects fixated after the target (intervening objects), followed by a four-alternative forced choice recognition test. Results showed that the probability of target refixation increased with the number of fixated intervening objects, and these refixations produced a 16% accuracy benefit over the first five intervening-object conditions. Additionally, refixations most frequently occurred after fixations on only one to two other objects, regardless of the intervening-object condition. These behaviors could not be explained by random or minimally constrained computational models; a VWM component was required to completely describe these data. We explain these findings in terms of a monitor-refixate rehearsal system: The activations of object representations in VWM are monitored, with refixations occurring when these activations decrease suddenly.

Coordinating spatial referencing using shared gaze.

To better understand the problem of referencing a location in space under time pressure, we had two remotely located partners (A, B) attempt to locate and reach consensus on a sniper target, which appeared randomly in the windows of buildings in a pseudorealistic city scene. The partners were able to communicate using speech alone (shared voice), gaze cursors alone (shared gaze), or both. In the shared-gaze conditions, a gaze cursor representing Partner A's eye position was superimposed over Partner B's search display and vice versa. Spatial referencing times (for both partners to find and agree on targets) were faster with shared gaze than with speech, with this benefit due primarily to faster consensus (less time needed for one partner to locate the target after it was located by the other partner). These results suggest that sharing gaze can be more efficient than speaking when people collaborate on tasks requiring the rapid communication of spatial information. Supplemental materials for this article may be downloaded from http://pbr.psychonomic-journals.org/content/supplemental.

Spatial asymmetries in viewing and remembering scenes: consequences of an attentional bias?

Given a single fixation, memory for scenes containing salient objects near both the left and right view boundaries exhibited a rightward bias in boundary extension (Experiment 1). On each trial, a 500-msec picture and 2.5-sec mask were followed by a boundary adjustment task. Observers extended boundaries 5% more on the right than on the left. Might this reflect an asymmetric distribution of attention? In Experiments 2A and 2B, free viewing of pictures revealed that first saccades were more often leftward (62%) than rightward (38%). In Experiment 3, 500-msec pictures were interspersed with 2.5-sec masks. A subsequent object recognition memory test revealed better memory for left-side objects. Scenes were always mirror reversed for half the observers, thus ruling out idiosyncratic scene compositions as the cause of these asymmetries. Results suggest an unexpected leftward bias of attention that selectively enhanced the representations, causing a smaller boundary extension error and better object memory on the views' left sides.

False memory 1/20th of a second later: what the early onset of boundary extension reveals about perception.

Errors of commission are thought to be caused by heavy memory loads, confusing information, lengthy retention intervals, or some combination of these factors. We report false memory beyond the boundaries of a view, boundary extension, after less than 1/20th of a second. Photographs of scenes were interrupted by a 42-ms or 250-ms mask, 250 ms into viewing, before reappearing or being replaced with a different view (Experiment 1). Postinterruption photographs that were unchanged were rated as closer up than the original views; when the photographs were changed, the same pair of closer-up and wider-angle views was rated as more similar when the closer view was first, rather than second. Thus, observers remembered preinterruption views with extended boundaries. Results were replicated when the interruption included a saccade (Experiment 2). The brevity of these interruptions has implications for visual scanning; it also challenges the traditional distinction between perception and memory. We offer an alternative conceptualization that shows how source monitoring can explain false memory after an interruption briefer than an eyeblink.

Transsaccadic representation of layout: what is the time course of boundary extension?

How rapidly does boundary extension occur? Across experiments, trials included a 3-scene sequence (325 ms/picture), masked interval, and repetition of 1 scene. The repetition was the same view or differed (more close-up or wide angle). Observers rated the repetition as same as, closer than, or more wide angle than the original view on a 5-point scale. Masked intervals were 100, 250, 625, or 1,000 ms in Experiment 1 and 42, 100, or 250 ms in Experiments 2 and 3. Boundary extension occurred in all cases: Identical views were rated as too "close-up," and distractor views elicited the rating asymmetry typical of boundary extension (wider angle distractors were rated as being more similar to the original than were closer up distractors). Most important, boundary extension was evident when only a 42-ms mask separated the original and test views. Experiments 1 and 3 included conditions eliciting a gaze shift prior to the rating test; this did not eliminate boundary extension. Results show that boundary extension is available soon enough and is robust enough to play an on-line role in view integration, perhaps supporting incorporation of views within a larger spatial framework.

Coordinating cognition: the costs and benefits of shared gaze during collaborative search.

Collaboration has its benefits, but coordination has its costs. We explored the potential for remotely located pairs of people to collaborate during visual search, using shared gaze and speech. Pairs of searchers wearing eyetrackers jointly performed an O-in-Qs search task alone, or in one of three collaboration conditions: shared gaze (with one searcher seeing a gaze-cursor indicating where the other was looking, and vice versa), shared-voice (by speaking to each other), and shared-gaze-plus-voice (by using both gaze-cursors and speech). Although collaborating pairs performed better than solitary searchers, search in the shared gaze condition was best of all: twice as fast and efficient as solitary search. People can successfully communicate and coordinate their searching labor using shared gaze alone. Strikingly, shared gaze search was even faster than shared-gaze-plus-voice search; speaking incurred substantial coordination costs. We conclude that shared gaze affords a highly efficient method of coordinating parallel activity in a time-critical spatial task.

Memory for the search path: evidence for a high-capacity representation of search history.

Using a gaze-contingent paradigm, we directly measured observers' memory capacity for fixated distractor locations during search. After approximately half of the search objects had been fixated, they were masked and a spatial probe appeared at either a previously fixated location or a non-fixated location; observers then rated their confidence that the target had appeared at the probed location. Observers were able to differentiate the 12 most recently fixated distractor locations from non-fixated locations, but analyses revealed that these locations were represented fairly coarsely. We conclude that there exists a high-capacity, but low-resolution, memory for a search path.

Marking rejected distractors: a gaze-contingent technique for measuring memory during search.

There is a debate among search theorists as to whether search exploits a memory for rejected distractors. We addressed this question by monitoring eye movements and explicitly marking objects visited by gaze during search. If search is memoryless, markers might be used to reduce distractor reinspections and improve search efficiency, relative to a no-marking baseline. However, if search already uses distractor memory, there should be no differences between marking and no-marking conditions. In four experiments, with stimuli ranging from Os and Qs to realistic scenes, two consistent data patterns emerged: (1) Marking rejected distractors produced no systematic benefit for search efficiency, as measured by reinspections, reaction times, or errors, and (2) distractor reinspection rates were, overall, extremely low. These results suggest that search uses a memory for rejected distractors, at least in those many real-world search tasks in which gaze is free to move.