Towards a Better Understanding of Nonstructural Carbohydrate Storage and Carbon Limitation in Trees

Nonstructural carbohydrates (NSC) are an important component of the carbon storage pool in trees and commonly used to assess whether tree growth under various conditions is carbon limited. However, we know very little about what causes variation in NSC levels and allocation among trees. While NSCs may accumulate passively when growth is carbon saturated, their storage may be active, competing with growth for carbon. If storage is mostly an active process, trees may maintain high NSC levels at the expense of potential growth, making NSC levels poor indicators of carbon saturated growth. To determine how growth and NSC allocation are related, we compared variation in the seasonal changes in NSC levels (NSC increment) with variation in radial growth in mature, canopy black oaks in the New Jersey Pine Barrens. Using experimental defoliation of saplings in a common garden and mature trees in the field, we also explored whether allocation shifts that favor storage reduce growth. Growth and NSC increment were positively correlated, indicating that storage was active, not the result of carbon-saturated growth. Defoliation reduced sapling growth, but increased the proportion of biomass allocated to NSCs. In adults, defoliation reduced growth for three years. However, while aboveground NSC levels may not have completely recovered by the end of the third year, belowground levels recovered after two years due to greater NSC allocation. Defoliation also changed the relationship between NSC increment and growth in the two years following defoliation, causing a shift in allocation that favored storage. The positive relationship between growth and NSC increment indicated that the allocation shift was not due to sink limitation. We conclude that storage is a high priority in these trees. In addition, carbon limiting events like defoliation can greatly alter carbon allocation by increasing the priority of storage, potentially in response to greater threats of carbon starvation. Our results indicate that carbon limitation to growth may occur not only because of decreased carbon availability but because of allocation shifts that reduce the priority of growth relative to other processes

Do cladistic and morphometric data capture common patterns of morphological disparity?

The distinctly non-random diversity of organismal form manifests itself in discrete clusters of taxa that share a common body plan. As a result, analyses of disparity require a scalable comparative framework. The difficulties of applying geometric morphometrics to disparity analyses of groups with vastly divergent body plans are overcome partly by the use of cladistic characters. Character-based disparity analyses have become increasingly popular, but it is not clear how they are affected by character coding strategies or revisions of primary homology statements. Indeed, whether cladistic and morphometric data capture similar patterns of morphological variation remains a moot point. To address this issue, we employ both cladistic and geometric morphometric data in an exploratory study of disparity focussing on caecilian amphibians. Our results show no impact on relative intertaxon distances when different coding strategies for cladistic characters were used or when revised concepts of homology were considered. In all instances, we found no statistically significant difference between pairwise Euclidean and Procrustes distances, although the strength of the correlation among distance matrices varied. This suggests that cladistic and geometric morphometric data appear to summarize morphological variation in comparable ways. Our results support the use of cladistic data for characterizing organismal disparity

The ironic effect of national identification on support for collective action

Peer reviewe

Full throttle: Are motorcyclists as risk-taking as we think?

Background:Motorcycling, whether thought of as a leisure activity, hobby, or social activity, can add quality to one’s life. Being a member of a motorcycle club may promote a sense of community, while motorcycling itself may increase feelings of awe and joy. When conceptualized as part of one’s social identity, motorcycling tends to be associated with an unfavourable image or stereotype, wherein motorcyclists’ personalities are characterized as rebellious, prone to risk-taking behaviour, and masculine (regardless of the motorcyclist’s gender). The accuracy of this stereotype is unclear, particularly as perceived by non-motorcyclists, such as car drivers. Accordingly, the overall purpose of this exploratory study was to describe the personality profile of motorcyclists from a basic trait perspective (Big 5) and assess its congruence with non-motorcyclists’ perceptions of the “typical” motorcyclist’s personality.Participants and procedure:A cross-sectional online survey (N = 376) consisting of motorcyclists (n = 194) and car drivers (n = 182) collected information on personality traits (self-report or perceived), riding behaviour (motorcyclists only), and well-being.Results:The results show that car drivers perceive motorcyclists to be more disinhibited, less open, more neurotic, less agreeable, and less conscientious than motorcyclists self-report.Conclusions:Car drivers’ perceptions of motorcyclists seem to be more negative than their actual personalities, suggesting an unfavoura-ble judgement of that community

Visualizing sound emission of elephant vocalizations: evidence for two rumble production types

Recent comparative data reveal that formant frequencies are cues to body size in animals, due to a close relationship between formant frequency spacing, vocal tract length and overall body size. Accordingly, intriguing morphological adaptations to elongate the vocal tract in order to lower formants occur in several species, with the size exaggeration hypothesis being proposed to justify most of these observations. While the elephant trunk is strongly implicated to account for the low formants of elephant rumbles, it is unknown whether elephants emit these vocalizations exclusively through the trunk, or whether the mouth is also involved in rumble production. In this study we used a sound visualization method (an acoustic camera) to record rumbles of five captive African elephants during spatial separation and subsequent bonding situations. Our results showed that the female elephants in our analysis produced two distinct types of rumble vocalizations based on vocal path differences: a nasally- and an orally-emitted rumble. Interestingly, nasal rumbles predominated during contact calling, whereas oral rumbles were mainly produced in bonding situations. In addition, nasal and oral rumbles varied considerably in their acoustic structure. In particular, the values of the first two formants reflected the estimated lengths of the vocal paths, corresponding to a vocal tract length of around 2 meters for nasal, and around 0.7 meters for oral rumbles. These results suggest that African elephants may be switching vocal paths to actively vary vocal tract length (with considerable variation in formants) according to context, and call for further research investigating the function of formant modulation in elephant vocalizations. Furthermore, by confirming the use of the elephant trunk in long distance rumble production, our findings provide an explanation for the extremely low formants in these calls, and may also indicate that formant lowering functions to increase call propagation distances in this species'

Investigation at transonic speeds of the lateral-control and hinge-moment characteristics of a flap-type spoiler aileron on a 60 degree delta wing

This paper present results of an investigation of the lateral-control and hinge-moment characteristics of a 0.67 semispan flap-type spoiler aileron on a semispan thin 60 degree delta wing at transonic speeds by the reflection-plane technique. The spoiler-aileron had a constant chord of 10.29 percent mean aerodynamic chord and was hinged at the 81.9-percent-wing-root-chord station. Tests were made with the spoiler aileron slot open, partially closed, and closed. Incremental rolling-moment coefficients were obtained through a Mach number range of 0.62 to 1.08. Results indicated reasonably linear variations of rolling-moment and hinge-moment coefficients with spoiler projection except at spoiler projections of less than -2 percent mean aerodynamic chord and angles of attack greater than 12 degrees with results generally independent of slot geometry

Full throttle: are motorcyclists as risk-taking as we think?

Background:Motorcycling, whether thought of as a leisure activity, hobby, or social activity, can add quality to one’s life. Being a member of a motorcycle club may promote a sense of community, while motorcycling itself may increase feelings of awe and joy. When conceptualized as part of one’s social identity, motorcycling tends to be associated with an unfavourable image or stereotype, wherein motorcyclists’ personalities are characterized as rebellious, prone to risk-taking behaviour, and masculine (regardless of the motorcyclist’s gender). The accuracy of this stereotype is unclear, particularly as perceived by non-motorcyclists, such as car drivers. Accordingly, the overall purpose of this exploratory study was to describe the per-sonality profile of motorcyclists from a basic trait perspective (Big 5) and assess its congruence with non-motorcyclists’ perceptions of the “typical” motorcyclist’s personality.Participants and procedure:A cross-sectional online survey (N = 376) consisting of motorcyclists (n = 194) and car drivers (n = 182) collected information on personality traits (self-report or perceived), riding behaviour (motorcyclists only), and well-being.Results:The results show that car drivers perceive motorcyclists to be more disinhibited, less open, more neurotic, less agreeable, and less conscientious than motorcyclists self-report.Conclusions:Car drivers’ perceptions of motorcyclists seem to be more negative than their actual personalities, suggesting an unfavoura-ble judgement of that community.Background:Motorcycling, whether thought of as a leisure activity, hobby, or social activity, can add quality to one’s life. Being a member of a motorcycle club may promote a sense of community, while motorcycling itself may increase feelings of awe and joy. When conceptualized as part of one’s social identity, motorcycling tends to be associated with an unfavourable image or stereotype, wherein motorcyclists’ personalities are characterized as rebellious, prone to risk-taking behaviour, and masculine (regardless of the motorcyclist’s gender). The accuracy of this stereotype is unclear, particularly as perceived by non-motorcyclists, such as car drivers. Accordingly, the overall purpose of this exploratory study was to describe the per-sonality profile of motorcyclists from a basic trait perspective (Big 5) and assess its congruence with non-motorcyclists’ perceptions of the “typical” motorcyclist’s personality.Participants and procedure:A cross-sectional online survey (N = 376) consisting of motorcyclists (n = 194) and car drivers (n = 182) collected information on personality traits (self-report or perceived), riding behaviour (motorcyclists only), and well-being.Results:The results show that car drivers perceive motorcyclists to be more disinhibited, less open, more neurotic, less agreeable, and less conscientious than motorcyclists self-report.Conclusions:Car drivers’ perceptions of motorcyclists seem to be more negative than their actual personalities, suggesting an unfavoura-ble judgement of that community

Search for gravitational waves from binary inspirals in S3 and S4 LIGO data

We report on a search for gravitational waves from the coalescence of compact binaries during the third and fourth LIGO science runs. The search focused on gravitational waves generated during the inspiral phase of the binary evolution. In our analysis, we considered three categories of compact binary systems, ordered by mass: (i) primordial black hole binaries with masses in the range 0.35 M(sun) < m1, m2 < 1.0 M(sun), (ii) binary neutron stars with masses in the range 1.0 M(sun) < m1, m2 < 3.0 M(sun), and (iii) binary black holes with masses in the range 3.0 M(sun)< m1, m2 < m_(max) with the additional constraint m1+ m2 < m_(max), where m_(max) was set to 40.0 M(sun) and 80.0 M(sun) in the third and fourth science runs, respectively. Although the detectors could probe to distances as far as tens of Mpc, no gravitational-wave signals were identified in the 1364 hours of data we analyzed. Assuming a binary population with a Gaussian distribution around 0.75-0.75 M(sun), 1.4-1.4 M(sun), and 5.0-5.0 M(sun), we derived 90%-confidence upper limit rates of 4.9 yr^(-1) L10^(-1) for primordial black hole binaries, 1.2 yr^(-1) L10^(-1) for binary neutron stars, and 0.5 yr^(-1) L10^(-1) for stellar mass binary black holes, where L10 is 10^(10) times the blue light luminosity of the Sun.Comment: 12 pages, 11 figure

Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo

We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole (PBH) binary coalescence with component masses in the range 0.2--$1.0 M_\odot$. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing non-spinning black holes with masses in the range 0.2--$1.0 M_\odot$, we place an observational upper limit on the rate of PBH coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.