Search

Background: Arboricultural tree climbing is inherently dangerous, in part because of the possibility of failure of the tie-in point (TIP). To help climbing arborists choose TIPs wisely, we have conducted several studies to quantify the magnitude and frequency of loading associated with arboricultural tree climbing. One parameter that has not been previously studied is whether the choice of climbing line influences loads experienced by a TIP as a climbing arborist ascends. Methods: The lead author conducted trials in which he ascended to 3 TIPs (in different trees) using 2 ascent techniques and 3 different climbing lines. During each trial, we measured loads at the TIP, and from the resulting time histories analyzed the magnitude and frequency of loading. We compared the effect of ascent technique, climbing line, and their interaction on the magnitude and frequency of loading. Results: During trials, the magnitude of loading varied between 1.1 and 1.5 times the lead author’s weight and did not differ between ascent techniques, climbing lines, or their interaction. Loading frequency varied among ascent techniques, but not climbing lines. Footlocking induced loads at a wide range of frequencies, but 2 distinct frequencies were associated with ropewalking. Conclusion: Climbing arborists can use the results of this and our previous studies to help select a suitable TIP. It is important for climbing arborists to understand the magnitude of forces associated with ascending into and working in a tree. Future studies should investigate the load-bearing capacity of a TIP from the ground.

Practitioners who assess the risk associated with urban trees often factor in the presence or absence of visual tree defects when determining whether a tree may fail. Although these defects are a main fixture in many tree risk assessment systems and best-management practices, the research supporting their usefulness in predicting tree failure during storms is limited. When looking at past research involving populations of storm-damaged trees, several defects have never predicted failure (or have been associated with reduced rates of failure). In this study, we took a closer look at four such defects: codominant branches; branch unions with included bark; multiple stems originating from the same point; and overextended branches. After Hurricane Ian, we revisited 1518 risk-assessed trees where one of these four defects was identified as the primary condition of concern. Fourteen of these trees experienced branch failure during the storm (which hit the study area as a downgraded tropical storm). Upon closer inspection, none of these failures occurred at the defect of concern. Our findings indicate that none of the defects assessed appeared to increase the likelihood of tree failure in the species tested. Our results are in line with past research on these defects derived from post-storm assessments and analysis.

Practitioners who assess the risk associated with urban trees often factor in the presence or absence of visual tree defects when determining whether a tree may fail. While these defects are a main fixture in many tree risk assessment systems and best management practices, the research supporting their usefulness in predicting tree failure during storms is limited. When looking at past research involving populations of storm-damaged trees, there are several defects that have never predicted failure (or have been associated with reduced rates of failure). In this study, we took a closer look at four such defects: codominant branches; branch unions with included bark; multiple stems originating from the same point; and overextended branches. After Hurricane Ian, we revisited 1519 risk assessed trees where one of these four defects was identified as the primary condition of concern. Fourteen of these trees experienced branch failure during the storm (which hit the study area as a downgraded tropical storm). Upon closer inspection, none of these failures occurred at the defect of concern. Our findings indicate that none of the defects assessed appeared to increase the likelihood of tree failure in the species tested. Our results are in line with past research on these defects derived from post-storm assessments and analysis.

Trees provide numerous benefits in urban areas, including improving stormwater retention and filtration, removing gaseous and particulate pollutants from the air, sequestering atmospheric carbon, and reducing ambient temperature. However, trees also pose risks in urban areas. Trees growing near overhead electrical utility lines cause a large proportion of electrical power outages. To mitigate this risk, arborists frequently and sometimes severely prune trees near overhead utilities for clearance and to reduce the likelihood of failure. Ostensibly, urban trees distant from utility lines are not pruned as frequently or severely. This study aimed to (i) assess factors related to both individual trees and the sample populations of trees growing near and away from overhead utility lines, and (ii) determine whether those factors differed between the two groups. In total, 200 utility easement plots and 200 non-utility control plots were distributed in Eversource Energy’s distribution territories, encompassing 2361 trees in total. Diameter at breast height (DBH), crown height and spread, percent crown missing, percent twig dieback, and likelihood of failure were gathered for each tree in the study. These variables were compared individually among study groups, and used as inputs to calculate estimated ecosystem service delivery using USFS iTree Eco v6. Overall, trees in control plots were larger and delivered more ecosystem services, per tree, than trees in utility plots. However, on a population level, trees in utility plots were more populous and delivered more aggregate ecosystem services than those in control plots. Although the aesthetics of utility tree pruning is often debated, there were no differences in likelihood of failure ratings between trees in control and utility plots. These findings may help to frame trees near overhead utility lines, commonly seen as risks or eyesores, as valuable green infrastructure and community assets.

Arborists commonly investigate the extent of stem decay to assess the likelihood of stem failure when conducting tree risk assessments. Studies have shown that: (i) arborists can sometimes judge the extent of internal decay based on external signs; (ii) sophisticated tools can reliably illustrate the extent of internal decay; and (iii) assessing components of tree risk can be highly subjective. We recruited 18 experienced tree risk assessors who held the International Society of Arboriculture’s Tree Risk Assessment Qualification (TRAQ) to assess the likelihood of stem failure due to decay after each of five consecutive assessments on 30 individuals of 2 genera. The five assessment techniques, in stepwise order, were: (1) observing visually, (2) sounding the trunk with a mallet, (3) viewing a scaled diagram of the cross-section that revealed sound and decayed wood ascertained from resistance drilling, (4) viewing sonic and electrical resistance tomograms, and (5) consulting with a peer. For each technique, the assessors assigned two or more likelihood of failure ratings (LoFRs) for at least 83% of trees, which were proportionally greatest after the assessors viewed the tomograms; the proportions did not differ among the other four assessment techniques. Covariates that influenced the distribution of the LoFRs included percent of the cross-section that was decayed, and assessors’ experience using resistance drilling devices and tomography in regular practice. Practitioners should be aware that disagreement on the likelihood of tree failure exists even among experienced arborists.

Urban trees are often more sun- and wind-exposed than their forest-grown counterparts. These environmental differences can impact how many species grow – impacting trunk taper, crown spread, branch architecture, and other aspects of tree form. Given these differences, windthrow models derived from traditional forest production data sources may not be appropriate for urban forest management. Additionally, visual abnormalities historically labeled as “defects” in timber production may not have a significant impact on tree failure potential. In this study, we look at urban tree failures associated with Hurricane Irma in Tampa, Florida, USA. We used spatial analysis to determine if patterns of failure existed among our inventoried trees. We also looked at risk assessment data to determine which visual defects were the most common and the most likely to be associated with branch or whole-tree failure. Results indicate that there was no spatial pattern associated with the observed tree failures – trees failed or withstood the storm as individuals. While some defects like decay and dead wood were associated with increased tree failure, other defects like weak branch unions and poor branch architecture were less problematic.

Broadcast from Havana, Cuba, but intended for audiences in the United States, Radio Free Dixie was the work of the civil rights leader Robert F. Williams. Airing from 1962 until 1966, the program carefully used music, news, and commentary to convey a militant message of armed self-defense and a critique of American imperialism and racism. While most scholars have focused on William’s spoken commentaries, this article aims to reconsider the role of music on Radio Free Dixie. By examining playlists transcribed and identified from archival broadcasts held at the Bentley Historical Library of the University of Michigan, the article explores three themes. 1) The playlists draw attention to the care with which the music for Radio Free Dixie was selected and how phonograph records were acquired while in Cuba. 2) When viewed through the lens of parrēsia, or what Michel Foucault theorizes as the act of “truth-telling,” the playlists facilitate an argument about how music and speech co-constitute Radio Free Dixie’s parrēsiastic subject by isolating particular moments in the broadcasts where the truth-telling occurs at the intersection of music and speech. 3) Consideration of special episodes given wholly over to music allows for an examination of musical genres employed on Radio Free Dixie and their degrees of overt and coded utterance. Finally, the article considers what it might mean to make militancy audible.

During pruning, shortening branches to decrease crown size significantly affected the vibration properties and mass of trees, but the progressive removal of lower branches only altered mass—not vibration properties. During pruning, arborists often intend to increase a tree’s resistance to wind loading by selectively removing branches, but there are few studies examining the efficacy of these interventions, especially for large, open-grown trees. This study examined the vibration properties (frequency and damping ratio) and mass of Senegal mahogany (Khaya senegalensis) and rain tree (Samanea saman) before and after a series of pruning treatments: crowns were either raised or reduced at incremental severities between 0 and 80%. For both species, mass decreased faster on reduced than raised trees. The frequency and damping ratio of trees varied with the severity of pruning for reduced, but not raised, trees. The frequency of reduced trees generally increased with pruning severity. In contrast, damping ratio of reduced trees generally decreased with the severity of pruning, except for the unique increase in damping ratio on Senegal mahoganies reduced by 10–20%. Although the vibration properties and mass will change as trees grow after pruning, the results suggest that arborists can reduce trees to change their vibration properties and concomitant response to wind loads, but arborists should reduce trees by a small amount to avoid the adverse decrease in damping ratio.

Rigging is a dangerous arboricultural practice that involves working at height with sharp tools; it also induces large forces and dynamic motion of both the rigged piece and the tree itself. Manufacturers have recently developed alternatives to conventional arborist rigging blocks (with a rotating sheave) with the intention of increasing friction in the block to reduce the likelihood of anchor failure in the tree. We measured tension in the fall and lead of rigging ropes run through a variety of blocks (with and without rotating a sheave) in three test methods—dropping, raising, and lowering a mass. The ratio of tension in the lead to tension in the fall of the rope differed among test methods, blocks, ropes, and their interaction. Some of the differences were expected from the underlying physics, but it was not true that blocks without a rotating sheave consistently provided more friction. Considering the inconsistent findings, rigging a less massive piece seems to be a better way to reduce the likelihood of anchor failure than managing friction in the block.

Background Sentiments of vaccine hesitancy and distrust in public health institutions have complicated the government-led coronavirus disease 2019 (COVID-19) vaccine control strategy in the United States. As the first to receive the vaccine, COVID-19 vaccine attitudes among frontline workers are consequential for COVID-19 control and public opinion of the vaccine. Methods In this study, we used a repeated cross-sectional survey administered at 3 time points between 24 September 2020 and 6 February 2021 to a cohort of employees of the University of California, Los Angeles Health and the Los Angeles County Fire Department. The primary outcome of interest was COVID-19 vaccination intent and vaccine uptake. Results Confidence in COVID-19 vaccines and vaccine uptake rose significantly over time. At survey 1, confidence in vaccine protection was 46.4% among healthcare workers (HCWs) and 34.6% among first responders (FRs); by survey 3, this had risen to 90.0% and 75.7%, respectively. At survey 1, about one-third of participants intended to receive a vaccine as soon as possible. By survey 3, 96.0% of HCWs and 87.5% of FRs had received a COVID-19 vaccine. Conclusions Attitudes toward vaccine uptake increased over the study period, likely a result of increased public confidence in COVID-19 vaccines, targeted communications, a COVID-19 winter surge in Los Angeles County, and ease of access from employer-sponsored vaccine distribution.

1. Interactions between wind and trees control energy exchanges between the atmosphere and forest canopies. This energy exchange can lead to the widespread damage of trees and wind is a key disturbance agent in many of the world’s forests. However, most research on this topic has focused on conifer plantations, where risk management is economically important, rather than broadleaf forests, which dominate the forest carbon cycle. This study brings together all available tree motion time-series data to systematically evaluate the factors influencing tree responses to wind loading, including data from both broadleaf and coniferous trees in forests and open environments. 2. We found that the two most descriptive features of tree motion were: (a) the fundamental frequency, which is a measure of the speed at which a tree sways and is strongly related to tree height, and (b) the slope of the power spectrum, which is related to the efficiency of energy transfer from wind to trees. Intriguingly, the slope of the power spectrum was found to remain constant from medium to high wind speeds for all trees in this study. This suggests that, contrary to some predictions, damping or amplification mechanisms do not change dramatically at high wind speeds and therefore wind damage risk is related, relatively simply, to wind speed. 3. Conifers from forests were distinct from broadleaves in terms of their response to wind loading. Specifically, the fundamental frequency of forest conifers was related to their size according to the cantilever beam model (i.e. vertically distributed mass), whereas broadleaves were better approximated by the simple pendulum model (i.e. dominated by the crown). Forest conifers also had a steeper slope of the power spectrum. We interpret these finding as being strongly related to tree architecture, i.e. conifers generally have a simple shape due to their apical dominance, whereas broadleaves exhibit a much wider range of architectures with more dominant crowns.

Sonic tomography can be used to examine reductions in the load-bearing capacity of tree parts with internal defects, but the limitations of sonic tomography and mathematical methods must be considered. The measurement and assessment of internal defects is an important aspect of tree risk assessment. Although there are several methods for estimating the reduced load-bearing capacity of trees with internal defects, the advancement of these methods has not kept pace with improvements to methods used to measure the internal condition of trees, such as sonic tomography. In this study, the percent reduction to the section modulus, ZLOSS (%), caused by internal defects was estimated using 51 sonic tomograms collected from three tree species, and the accuracy of measurements was assessed using the destructively measured internal condition of the corresponding cross sections. In tomograms, there was a repeated underestimation of the percent total damaged area, AD (%), and a repeated overestimation of the offset distance between the centroid of the trunk and the centroid of the largest damaged part, LO (m). As a result, ZLOSS determined using tomograms was mostly less, in absolute terms, than that determined from destructive measurements. However, the accuracy of these estimates improved when using colors associated with intermediate sonic velocities to select damaged parts in tomograms, in addition to the colors explicitly associated with the slowest sonic velocities. Among seven mathematical methods used to estimate ZLOSS, those accounting for LO were more accurate than others neglecting it. In particular, a numerical method incorporating greater geometric detail, called zloss, gave estimates that were consistently better than six other analytical methods.

Trees in residential landscapes provide many benefits, but can injure persons and damage property when they fail. In hurricane-prone regions like Florida, USA, the regular occurrence of hurricanes has provided an opportunity to assess factors that influence the likelihood of wind-induced tree failure and develop species failure profiles. We assessed open-grown trees in Naples, Florida, following the passage of Hurricane Irma in September 2017 to determine the effect of relevant factors on the degree of damage sustained by individual trees. Of 4034 assessed individuals (n = 15 species), 74% sustained no damage, 4% sustained only minor damage (i.e., minimal corrective pruning needed), 6% sustained significant damage (i.e., major corrective pruning needed), and 15% were whole-tree failures (i.e., overturned trees or trees requiring removal). The proportion of individuals in each damage category varied among species, stem diameter at 1.4 m above ground, and the presence of utility lines, which was a proxy for maintenance. We compared our results with the findings of seven previous hurricanes in the region to explore species&rsquo, resilience in hurricanes.

Working in trees is an inherently dangerous profession, with a higher than average fatality rate. Climbers secure themselves with a rope and harness to a tie-in point to ascend into and work in a tree, but it can be difficult—if not impossible—to assess the safety of a tie-in point from the ground. Very little experimental work has described the loads associated with ascending into and working in trees, but it is critical to understand them to assess safety. We measured loads induced by competitors in the ascent event at the International Tree Climbing Competition and analyzed their amplitude and frequency. We also measured the sway frequency of a small sample of tie-in points. Load time histories revealed repeated cycling between maximal and minimal impulse loads at a particular frequency as competitors ascended. After accounting for competitors’ weight, ascending using a single foot ascender induced greater loads than footlocking or using two foot ascenders. Footlocking induced loads at a lower frequency than using two foot ascenders. Although the loading frequency for all techniques was higher than the first natural sway frequency of tie-in points, the atypically large tie-in point used during the ascent event precludes extrapolation to tie-in points of typical size. Since there are very few data to quantify loads during an ascent, and many other relevant aspects to quantify in order to estimate the likelihood of failure of a tie-in point, the results will be useful to future studies.

Cabling co-dominant stems at different heights and tensions altered neither frequency nor damping ratio, but the location and proportion of pruned crown mass significantly influenced both frequency and damping ratio. Amenity trees provide many benefits, but can damage property and injure persons. Arboricultural treatments like pruning and cabling intend to reduce the likelihood of tree failure, but the effect of such treatments on tree sways is not well known. We measured the sway response (frequency and damping ratio) of seven Quercus rubra L. before and after consecutive arboricultural treatments, including the addition a climber swaying freely or secured rigidly to the tree. We also quantified crown architecture and tree mass. Cabling two co-dominant stems did not influence sway response, but pruning increased frequency and decreased damping ratio. The effect of pruning depended on the proportion and location of pruned crown mass. Adding a climber predictably affected frequency and damping ratio in accordance with physical principles. This work adds novel insights to the understanding of tree sways, since previous studies have been limited by single trees, pruning types, or pruning severities.

This paper presents a method for assessing the safety of tree branches subject to unorthodox climbing approaches and possible falls. The method entails finite element modeling of the tree branch, experimentally or analytically determining loads associated with an ascending or falling climber, and computing stresses and safety factor along the length of the branch using dynamic structural analysis. A case study example is presented for an Ulmus americana L. branch on the campus of the University of Massachusetts, Amherst. This tree and branch were climbed using an unorthodox and controversial method during a competition in 2014. Case study models demonstrate that during an ascent, a climber’s skill has a significant effect on branch stresses, and during a simulated fall, the climber’s mass and fall distance are the key determinants of branch stresses. For loads induced during an ascent, safety factors for branches ranged between 3 and 4; for loads induced during a fall, safety factors were as low as 1.2. These values are dangerously low given the uncertainty of branch material properties. Climbers should be extremely cautious when attempting unorthodox climbing techniques.

While the ontology of musical works is a venerable theme in the philosophy of music, works of classical music have been the primary focus of study. This essay displaces that focus by considering the ontology of musical works in relation to jazz ‘standards’. Responding primarily to realist conceptions of musical works for performance, the essay outlines an emergent, non-essentialist, network-based ontology of jazz standards. By focusing on two key operations—replication and nomination—a philosophical and musicological argument is presented where ‘work-determinative’ properties are shown to be sufficient but not necessary. Under this concept, works are corrigible and subject to mediation. Not only do subsequent performances change the nature of the work, the very act of ‘replication’ (or musical reproduction) requires social mediation. After presenting the argument, a series of broad contrasts are drawn between the network-based concept of musical works and the realist view.

Despite the inherent danger that accompanies rigging trees, very few studies have investigated this important aspect of arboricultural practice. Following work we completed in 2009, there appear to be no studies that address limitations of our work. Using similar methods to our original work (Kane et al., 2009), we explored additional aspects of rigging and built upon our previous study, considering trees with co-dominant stems and measuring acceleration of the stem near the rigging block. The mass of the piece was the best predictor of force in the rigging, superseding other variables related to the piece (length, diameter) or the rigging (length of rope, fall distance, angle and depth of the notch). Force per unit mass was greatest when “shock loading” the rigging with pieces of the branchless trunk. Friction in the block appeared to be greater than previously considered, which reduces the effectiveness of the block in converting kinetic energy of the rigged piece to elastic strain in the rigging rope. Since the mechanics of rigging is complicated, more empirical data are needed to lend insight and help practitioners work more safely.

Summary The architecture of trees is the result of constrained, morphologically plastic growth – constrained by an underlying architectural model embedded in their genome, the structure of which can be significantly altered during growth to match the changing environmental conditions to which the tree is exposed. Here, we examined the hypothesis that crowding from neighbours should cause trees to optimize traits for light competition at the expense of wind resistance, with the reverse being true for trees lacking neighbours. Previous studies have examined the influence of light competition or wind resistance on shaping tree architecture, but few, if any, have simultaneously addressed trade-offs for optimizing these traits in response to crowding from neighbouring trees in forests, as compared to open-grown conditions. We studied the response of tree- and branch-level architectural traits of temperate, broad-leaved, deciduous tree species of differing shade tolerance and wood strength from multiple locations across the north-eastern United States. Trees ranged in size (4–83 cm diameter at 1·3 m) and crowding conditions (open- and forest-grown) and occupied different canopy positions. The open-grown trees represented a null condition, where the lack of neighbouring trees to shape architectural traits could be contrasted with the influence of different levels of crowding in forests. Our results show strong evidence for a tree neighbourhood-induced convergence of architectural traits across species and conditions, even when trees are growing in urban rather than natural forest conditions. After accounting for crowding, the effects of species and sample location contributed very little to explaining variation in architectural traits. One exception was crown dimensions, for which species-specific differences explained about 15% of the residual variation. Under open-grown conditions, alleviation of light competition caused trees to develop relatively large crowns and branches and a squat growth form suitable to resist greater wind exposure. By contrast, increasing shading from neighbouring trees caused forest-grown trees to become increasingly more spindly in the main stem, with slender branches sparsely distributed over a disproportionately large crown volume – presumably to maximize light capture. Although the latter is an intrinsically less wind-stable form, it can be adopted to increase light capture because neighbouring trees reduce exposure to the wind, which should greatly reduce the likelihood of stem breakage or uprooting under critical wind pressures. A lay summary is available for this article.

This article considers the relationship between audiotape's material affordances and the audibility of cultural practices. Not all changes in the materiality of sound media are audible to listeners, and not all changes in the audibility of cultural practices require changes in their material support. Thus focus on the affordances of sound technologies – those possibilities of sound technologies that may or may not be engaged by its users, and the wide range of practices that such technologies support – can help to connect materiality and audibility. I address the affordances of audiotape by examining a number of small case studies where established sonic practices encounter a transition from phonography to audiotape: musique concrète and the tape loop, serialist composition, and Les Paul's use of overdubbing. Finally, I consider the nature of the audiotape archive and its mode of access in order to pose some general questions about the meaning and use of audiotape's affordances.

International audience; The relationship between form and function in trees is the subject of a longstanding debate in forest ecology and provides the basis for theories concerning forest ecosystem structure and metabolism. Trees interact with the wind in a dynamic manner and exhibit natural sway frequencies and damping processes that are important in understanding wind damage. Tree-wind dynamics are related to tree architecture, but this relationship is not well understood. We present a comprehensive view of natural sway frequencies in trees by compiling a dataset of field measurement spanning conifers and broadleaves, tropical and temperate forests. The field data show that a cantilever beam approximation adequately predicts the fundamental frequency of conifers, but not that of broadleaf trees. We also use structurally detailed tree dynamics simulations to test fundamental assumptions underpinning models of natural frequencies in trees. We model the dynamic properties of greater than 1000 trees using a finite-element approach based on accurate three-dimensional model trees derived from terrestrial laser scanning data. We show that (1) residual variation, the variation not explained by the cantilever beam approximation, in fundamental frequencies of broadleaf trees is driven by their architecture; (2) slender trees behave like a simple pendulum, with a single natural frequency dominating their motion, which makes them vulnerable to wind damage and (3) the presence of leaves decreases both the fundamental frequency and the damping ratio. These findings demonstrate the value of new three-dimensional measurements for understanding wind impacts on trees and suggest new directions for improving our understanding of tree dynamics from conifer plantations to natural forests.

BACKGROUND About one-third of American adults have prediabetes and are at increased risk of type 2 diabetes. Mobile health (mHealth) technologies provide a scalable approach to diabetes prevention by encouraging physical activity (PA), weight loss, and adherence to a healthy diet in large numbers of patients. OBJECTIVE To identify factors associated with improvements in PA and glycated hemoglobin (A1c) measures among prediabetic adults who received a mobile intervention program (smartphone app in combination with a digital body weight scale) in a previously completed pilot study. METHODS We conducted a post hoc analysis of a 3-month prospective, single-arm, observational study using the Sweetch™ mHealth intervention among adults with prediabetes. Change in A1C was calculated as the difference between the 3-month and baseline A1C measurements and was categorized as decrease vs. no decrease. PA was evaluated using the total minutes and metabolic equivalent of task (MET)-hours per week. Change in MET-hours/week was categorized as increase vs. no increase. Age, sex, race, education, employment status, area deprivation, smartphone usage attitudes, and PA stage of change were compared between groups by outcomes of change in A1C and change in MET-hour/week. RESULTS A total of 37 adults received the final Sweetch mobile intervention and were included in the analysis. 62% were female and 81% were white, with average age of 57 years. The median [IQR] baseline A1C was 6.0% [5.8, 6.2]. A1C measure at 3-month was decreased in 24 (65%) participants when compared to baseline A1C. There was an inverse association between average MET-hours per week and change in A1C. Among participants whose A1C decreased vs. did not decrease, the MET-hours per week in last 2 weeks of study was 18.7 (8.4) and 15.0 (7.1), respectively (P=0.19), and the change in MET-hours per week was 2.1 (7.1) and 4.1(6.1), respectively (P=0.41). There were otherwise no statistically significant differences in participant factors by A1C and PA outcomes. CONCLUSIONS In this small pilot study, Sweetch mHealth intervention achieved comparable A1C response prediabetic adults with different individual, sociodemographic and anthropometric characteristics. CLINICALTRIAL ClincialTrials.gov NCT02896010; https://clinicaltrials.gov/ct2/show/NCT02896010 (Archived by WebCite at http://www.webcitation.org/6xJYxrgse)

While often considered “open grown,” urban trees are often found in relatively close proximity to neighboring trees, buildings, and other elements of urban infrastructure. These spatial arrangements may provide wind protection during severe weather events such as hurricanes. Beyond this very local scale, urban tree abundance and condition are often influenced by the greater sociodemographic context of the neighborhood or community where they are found. In an effort to assess the impact of these external factors on wind firmness after Hurricane Irma impacted Florida in 2017, we revisited three urban areas that had previously been inventoried using sample plots prior to the storm. At each plot we assessed storm damage and characterized surrounding protective elements (i.e., buildings and other trees) using a combination of ground-based and aerial approaches. This was then paired with block group level sociodemographic data derived from the United States Census. Logistic regression results confirmed previous research, showing that partial and whole tree failure were significantly more likely with a larger stem diameter (p = 0.001) and perceived/previously documented lower wind firmness (p = 0.004). However, our results disagreed with previous studies linking species diversity and resilience, showing tree failure was significantly more likely with higher Shannon Diversity Index (p = 0.008). A comparative geographically weighted logistic regression model also found that the higher proportions of African American residents and Hispanic residents, and the median age of residents were significant predictors of less likely tree failure in 30 %, 36 %, and 20 % of plots, respectively. However, this evidence was weak, compared to that of tree- and plot-level effects. Despite being a key predictor of interest, we did not see any significant protective effect from neighboring trees or structures.

Pruning is commonly used to mitigate the risk of tree failure by selectively removing tree parts exposed to the wind, but there have been few studies examining changes in wind loads after pruning, especially for large, open-grown trees. In this study, the wind-induced vibration and bending moments of Senegal mahogany (Khaya senegalensis) were monitored before and after a series of pruning treatments: crowns were either raised or reduced at incremental severities between 0 and 20 %. Under ambient wind loads, axial trunk deformation was measured using two displacement probes installed orthogonally on each tree, and each displacement probe was calibrated using a static load test to convert the measured trunk deformation to a bending moment. During each pruning treatment, ambient wind conditions and trunk deformation were monitored simultaneously for extended periods of time. As pruning severity increased, Fourier spectra showed that raised trees continued to vibrate primarily at their fundamental mode, but reduced trees vibrated progressively less than raised trees. Similarly, the average 30-minute maximum bending moment, associated with a given 30-minute maximum wind speed, decreased more for reduced than raised trees. Consistent with existing studies of small trees, the results suggest that arborists should reduce trees to decrease wind loads and, concomitantly, the likelihood of tree failure. Still, excessive leaf loss may constrain the usefulness of increasingly severe pruning on reduced trees: average leaf area index decreased by half on trees reduced by 20 %. More work is needed to understand the long-term physiological and mechanical consequences of pruning treatments.

The publication of Current of Music affords a reassessment of Theodor W. Adorno's years at the Princeton Radio Research Project. Although his encounter with the culture industry was made vivid and palpable during these years, this article reads Current of Music as a prolongation of his earlier concerns with a critique of Husserlian phenomenology and an analysis of Wagnerian phantasmagoria. I argue that Adorno's method for radio research is phenomenological, modified to accommodate dialectics. This modified phenomenology, renamed “physiognomy,” aims to expose phantasmagoria, the occultation of the means of production, masked in Husserlian phenomenology by its static categories and reductions. Given the prominent role of physiognomy as a form of social critique in Adorno's later writings, Current of Music offers a unique opportunity to see the concept at work in its earliest formation.

Slow growth following transplanting is characteristic of the establishment period, which has been studied for many years. Most of this work, however, has been conducted on trees transplanted in nurseries or favorable growing sites. In urban areas, many trees are transplanted into more challenging growing conditions, and very few studies have investigated establishment period of such trees. We analyzed ten years of transplanting records for the metropolitan Boston, MA, USA area to determine the establishment period of three species commonly planted as street trees {hedge maple [Acer campestre L.], London planetree [Platanus x acerifolia (Ait.) Willd.], and red oak [Quercus rubra L.]}. Using piecewise linear regression, we determined the “break point,” the intersection of two lines fitted to a scatter plot of caliper versus years after transplanting. The break point indicates the number of years after transplanting at which growth rate increases—the establishment period. We also analyzed whether site factors affected stem caliper. Establishment period varied among species: 2.1 years, 4.0 years, and 5.9 years for red oak, London planetree, and hedge maple, respectively. Site factors variably affected stem caliper of different species. Stem caliper of London planetree and red oak increased with greater sidewalk cut-out area. Tree grates in sidewalk cut-outs adversely affected stem caliper of London planetree. Our results can help practitioners manage street trees in the northeastern United States, but more work on trees transplanted in urban areas is necessary to understand the initial post-transplant growth of street trees.

Trees with root systems established well below grade due to deep planting or soil disturbance are common in urban landscapes, yet the long term effects of buried trunks and subsequent remediation strategies, such as root collar excavation are poorly documented. We evaluated the consequences of deep planting over a 10-year period on tree growth and stability, with and without root collar excavation, for red maple [Acer rubrum L. Red Sunset® (‘Franksred’)] and Northern red oak (Quercus rubra L.) planted at grade or 30-cm below grade. Sleeves to prevent soil-trunk contact were installed around trunks on a subset of deep trees. Root collar excavations were made during the 6th growing season for both species and trees were grown for an additional 4 and 3 growing seasons for red maples and Northern red oaks, respectively. Within two weeks of root collar excavations, pulling tests compared the effect of treatments on stability of red maples. Deep planting generally slowed growth of red maple but had no clear effect on Northern red oak. Root collar excavation had no lasting effect on growth of either species. Approximately 55% of deep red maples and 33% of deep Northern red oaks had roots crossing and in intimate contact with buried trunks, suggesting a potential for future girdling roots. Approximately 25% of deep maples had substantial adventitious rooting. All deep Northern red oaks had new roots emerging just above the first original structural roots but none were clearly adventitious. Trunk sleeves had no effect on growth for either species. Neither deep planting nor root collar excavation resulted in a loss of tree stability compared to trees planted at grade, although failure patterns varied among treatments. Overall, the biggest long term concern for deep-planted trees is the potential for girdling root formation.

Arboricultural climbing is inherently hazardous and although previous studies have investigated forces associated with ascents, abrupt stops during descents, and simulated falls, no studies have measured forces for typical climbing actions. Neither have studies measured motion of a tie-in point (TIP) and branch as a climber walked on the branch. We measured forces at the TIP and accelerations at the TIP and on a branch as a climber performed arboricultural climbing actions using two climbing lines and three climbing systems. Neither forces nor accelerations differed between climbing lines or systems, but covariates related to branch and TIP morphology were significant predictors of forces and accelerations in mechanically intuitive ways. As expected, forces measured for typical arboricultural climbing actions were less than those measured for ascents, abrupt stops during descents, and simulated falls. Results provide an important baseline for future work and can inform arboricultural safety standards to reduce the likelihood of injury while climbing.

Arboricultural safety standards exist in some countries, but it is unclear how many standards exist, how they compare to one another, and whether (and how many) countries share standards. To address these gaps, we obtained and analyzed arboricultural safety standards from 29 countries. We determined which safety categories were included in each standard to highlight frequently and infrequently included categories. We computed the proportion of all safety categories included in each standard, and we compared standards to determine their similarity with one another. Among 29 countries, 14 unique standards exist. Of 90 safety categories gleaned from the standards, 19 were included in all standards and 20 were included in all but 1 standard. Standards in Hong Kong, Poland, Singapore, Spain, and Sweden included at least 90 % of 90 safety categories. Our findings can be used by safety committees around the world to develop or revise local standards; they may also be used to help develop an international best management practices guide for safety.

Visual risk assessment remains the primary means of gauging urban tree safety and is a key facet of storm preparation and response. While past research has investigated the reproducibility of risk assessment methodologies (i.e., precision), few, if any, studies truly address the accuracy of current inspection practices – especially with regard to the characterization of likelihood of failure. In 2016, Hurricane Matthew made landfall in the Southeastern United States as a lower-intensity tropical storm, impacting several urban sites where tree risk assessments had been conducted in the recent past. After the storm, 2069 trees on 5 properties were revisited to assess storm damage. The vast majority (93%) of trees survived Matthew intact, with 6% of the assessed population suffering partial (i.e., branch) failure and the remaining 1% experiencing whole-tree failure. Failure rates differed by species, with age, and given the presence of external defects. The presence of dead branches (P-value

Previous studies that quantified or simulated loads on a tie-in point (TIP) during climber ascents, abrupt stops during descents, and falls considered crown-anchored stationary rope systems (SRS). But climbers also use basal-anchored SRS when working in trees, and because both parts of the rope—lead and fall—carry a load, the TIP presumably bears a greater load than on a crown-anchored SRS. In this study, tension in the fall and lead of a rope used in a basal-anchored SRS was measured during climber ascents and abrupt stops during descents. As expected, loads borne by the TIP were greater than on a crown-anchored SRS. Loads also varied among three species selected for varying degrees of bark roughness; greater loads were borne on the TIPs of a smooth-barked species. It was also noteworthy that pre-loading a TIP to determine its safety, which climbers do before ascending, increased the total load during ascents, presumably because tension set during the pre-load was not released in the fall of the rope prior to the ascent. To reduce the likelihood of TIP failure, climbers are advised to take care when selecting a TIP that will support a basal-anchored SRS.

Failure of a tie-in point (TIP) in tree climbing can have severe consequences, yet few studies have quantified the loads borne by and load-bearing capacity of TIPs. In two separate experiments, loads borne by the TIP during (i) abrupt stops while a climber descended and (ii) simulated climber falls were quantified for a variety of TIPs, rope types, and rope lengths (distance between the TIP and the application of the load). Peak load ratios (measured load divided by the weight of a simulated or actual climber) up to 10.6 were recorded, a potentially dangerous value with respect to both TIP failure and personal injury. Peak load ratios decreased as the length of rope between the TIP and the location of the simulated fall increased, and when trees were in leaf. Minimizing the potential fall distance during ascents is the surest way to reduce the likelihood of TIP failure and personal injury.

Arborists use speedlines to move debris; efficiently between the tree from which the debris is generated and the landing. To maintain vertical clearance over obstacles, speedlines are pretensioned, but there are no rigorous empirical data to quantify the tension in a pretensioned speedline when it carries a load. Neither has its deflection under load been quantified. We measured the mid-span deflection and tension at both anchors of a speedline under three added loads and three pretensions. Tension at both anchors increased with pretension and added loads up-line tension consistently exceeded down-line tension; and even for the greatest pretension and least added weight, mid-span deflection was substantial. Despite the increased tension in the speedline, bending stress at the anchors was comparatively low. Our results were largely consistent with analyses of logging skylines, despite the differences between components of each system.

Background: Prediabetes is a high-risk state for the future development of type 2 diabetes, which may be prevented through physical activity (PA), adherence to a healthy diet, and weight loss. Mobile health (mHealth) technology is a practical and cost-effective method of delivering diabetes prevention programs in a real-world setting. Sweetch (Sweetch Health, Ltd) is a fully automated, personalized mHealth platform designed to promote adherence to PA and weight reduction in people with prediabetes. Objective: The objective of this pilot study was to calibrate the Sweetch app and determine the feasibility, acceptability, safety, and effectiveness of the Sweetch app in combination with a digital body weight scale (DBWS) in adults with prediabetes. Methods: This was a 3-month prospective, single-arm, observational study of adults with a diagnosis of prediabetes and body mass index (BMI) between 24 kg/m2 and 40 kg/m2. Feasibility was assessed by study retention. Acceptability of the mobile platform and DBWS were evaluated using validated questionnaires. Effectiveness measures included change in PA, weight, BMI, glycated hemoglobin (HbA1c), and fasting blood glucose from baseline to 3-month visit. The significance of changes in outcome measures was evaluated using paired t test or Wilcoxon matched pairs test. Results: The study retention rate was 47 out of 55 (86%) participants. There was a high degree of acceptability of the Sweetch app, with a median (interquartile range [IQR]) score of 78% (73%-80%) out of 100% on the validated System Usability Scale. Satisfaction regarding the DBWS was also high, with median (IQR) score of 93% (83%-100%). PA increased by 2.8 metabolic equivalent of task (MET)–hours per week (SD 6.8; P=.02), with mean weight loss of 1.6 kg (SD 2.5; P