Light interception, gas exchange and carbon balance of different canopy zones of minimally and cane-pruned field-grown Riesling grapevines

Leaf area development, pre-dawn leaf water potential, spatial and temporal patterns of light interception and photosynthesis (A) of minimal pruned (MP) and cane-pruned vertical shoot positioned (VSP) fieldgrown Riesling grapevines were monitored in 2002 and 2003. In order to quantify the contribution of different canopy segments to whole vine carbon gain, diurnal single leaf gas exchange measurements were conducted several times during the season in 8 different canopy segments keeping leaves in their natural position. Carbon losses due to nocturnal respiration (DR) were estimated with a model describing the dependence of DR on temperature. MP vines had about 17 times more but less vigorous shoots with smaller leaves. Leaf area (LA) development was faster for MP than for VSP vines and LA was 2.5-3-fold higher for most of the season. Spatial and temporal patterns of average daily light interception were related to LA development and canopy dimensions for both MP and VSP vines during the first part of the season, but increased independent of LA until mid-October and more so for VSP than MP. Diurnal gas exchange measurements showed differences between canopy segments, measuring dates and systems. Differences between segments were related to light interception in the absence of water deficit, high leaf temperature and vapour pressure deficit. The higher light interception of MP vines caused pre-dawn water potential to decrease faster and to remain at lower levels during most of the season. This limited A more severely for leaves of MP vines in canopy segments which were well exposed to light. The estimated seasonal carbon gain per canopy segment was highest in the apical canopy zones for both canopy systems but carbon assimilation was higher for MP than for VSP vines in all segments with the exception of the interior canopy. Respiratory losses by leaves depended on night temperature and time during the season but generally varied between 3 and 7 % of the amount of carbon gained during the day. MP vines had slightly higher relative respiration losses than VSP vines. On a whole-plant basis, carbon gain of MP vines was between 5.7 (beginning of the season) and 2.2 times (end of season) higher than for VSP vines.

Quantifying Getting High Under One’s Own Power – A Comparison of Vertical Jump Height Measurement Methods

Countermovement jump (CMJ) height is widely used as a performance test, but the methods for assessing jump height are not standardized. Some assessment methods include the use of aerial time, take-off velocity or jump and reach systems such as the Vertec commonly seen in the NFL combine. The Vertec tests an athlete’s vertical jump by having the athlete jump and reach for the highest rotating vane they can tap with their hand. However, the validity of these different methods is not well established even though the governing force-motion relationships have been known for centuries. Specifically, motion of the body’s center of mass (COM) is determined by the vertical impulse (force x Δtime) prior to take-off. At present, the agreement, or lack thereof, between the commonly used field assessment methods and the actual height the COM attains during a CMJ is not known. Here, we hypothesized that body positional changes during jump and reach tests result in jump height overestimations. PURPOSE: To compare one of the most widely utilized field methods, the Vertec to the gold standard of impulse determined jump height. METHODS: Thirty total (n=15 male, n=15 female) participants ranging in athletic ability from recreational to competitive collegiate level athletes completed three maximal effort CMJs. Jump height was determined simultaneously from the impulse collected using Bertec force plates and a Vertec system. Only the athlete’s highest jump was used in analysis. Vertec and impulse determined jump heights were compared using paired samples t-tests, with alpha level set at 0.05. RESULTS: Vertec jump heights significantly exceeded impulse determined jump heights by an average of 14 cm: 54 ± 14 vs. 40 ±11 cm (P\u3c0.001) respectively. [Vertec range: 32 to 81 cm; Impulse range: 23 to 59 cm.] CONCLUSION: The Vertec measurement system appreciably overestimates the elevation of the body’s COM during vertical jumping, here by an average of 14 cm or 5.5 inches. There was also a trend for individuals with higher jump heights to have a greater difference between the two measurements. Suggesting that reaching ability may be more of a determinant of Vertec jump height than vertical impulse. This should be of interest to sports performance professionals that use this method to analyze progress. This disparity in quantification exists because the difference between standing and reaching hand height at jump apex over-represents the vertical elevation of the COM. This phenomenon is most likely to result from the asymmetrical nature of the reaching action as athletes strike the Vertec vanes. It is also important for sport performance professionals that use the Vertec method to recognize that their athlete’s do not jump as high as they currently believe

Sprinting with an amputation: Some race-based lower-limb step observations.

BACKGROUND: T44 sprinting with an amputation is still in a state of relative infancy. Future scope for athletic training and prosthetic limb development may be assisted with a better understanding of information derived from T44 athletes when under race-based conditions. OBJECTIVES: To investigate the behaviour of step count and step frequency when under competitive conditions. STUDY DESIGN: The study comprises two elements: (1) a video-based analysis of race-based limb-to-limb symmetry and (2) a video-based analysis of race-based step count. METHODS: Video analysis of several major events from 1996-2012 are assessed for step count and step limb-to-limb symmetry characteristics. RESULTS: The video analysis highlights limb-to-limb imbalances greater than those indicated in the previous literature. A low step count is determined to be desirable for success in the 100-m event. CONCLUSION: Future analysis of athletes with a lower-limb amputation would be worthwhile when placed under race-based conditions as the limb-to-limb behaviour is more exaggerated than those seen in typical studies held within a laboratory setting. The within-event behaviour of step counts requires further investigation to establish where these take place or whether it is a cumulative step length issue. CLINICAL RELEVANCE: This article increases the understanding of the race-based behaviour of amputee athletes and provides more information to contribute to any discussions on the performance of lower-limb prostheses

Impact of harness attachment point on kinetics and kinematics during sled towing.

Resisted sprint training is performed in a horizontal direction, and involves similar muscles, velocities and ranges of motion (ROM) to those of normal sprinting. Generally, sleds are attached to the athletes via a lead (3m) and harness; the most common attachment points are the shoulder or waist. At present, it is not known how the different harness point's impact on the kinematics and kinetics associated with sled towing (ST). The aim of the current investigation was to examine the kinetics and kinematics of shoulder and waist harness attachment points in relation to the acceleration phase of ST. Fourteen trained males completed normal and ST trials, loaded at 10% reduction of sprint velocity. Sagittal plane kinematics from the trunk, hip, knee and ankle were measured, together with stance phase kinetics (third foot-strike). Kinetic and kinematic parameters were compared between harness attachments using one-way repeated measures analysis of variance. The results indicated that various kinetic differences were present between the normal and ST conditions. Significantly greater net horizontal mean force, net horizontal impulses, propulsive mean force and propulsive impulses were measured (p>0.05). Interestingly, the waist harness also led to greater net horizontal impulse when compared to the shoulder attachment (p = 0.000). In kinematic terms, ST conditions significantly increased peak flexion in hip, knee and ankle joints compared to the normal trials (p<0.05). Results highlighted that the shoulder harness had a greater impact on trunk and knee joint kinematics when compared to the waist harness (p<0.05). In summary, waist harnesses appear to be the most suitable attachment point for the acceleration phase of sprinting. Sled towing with these attachments resulted in fewer kinematic alterations and greater net horizontal impulse when compared to the shoulder harness. Future research is necessary, in order to explore the long-term adaptations of these acute changes

The Dynamic Processing of CD46 Intracellular Domains Provides a Molecular Rheostat for T Cell Activation

Adequate termination of an immune response is as important as the induction of an appropriate response. CD46, a regulator of complement activity, promotes T cell activation and differentiation towards a regulatory Tr1 phenotype. This Tr1 differentiation pathway is defective in patients with MS, asthma and rheumatoid arthritis, underlying its importance in controlling T cell function and the need to understand its regulatory mechanisms. CD46 has two cytoplasmic tails, Cyt1 and Cyt2, derived from alternative splicing, which are co-expressed in all nucleated human cells. The regulation of their expression and precise functions in regulating human T cell activation has not been fully elucidated.Here, we first report the novel role of CD46 in terminating T cell activation. Second, we demonstrate that its functions as an activator and inhibitor of T cell responses are mediated through the temporal processing of its cytoplasmic tails. Cyt1 processing is required to turn T cell activation on, while processing of Cyt2 switches T cell activation off, as demonstrated by proliferation, CD25 expression and cytokine secretion. Both tails require processing by Presenilin/γSecretase (P/γS) to exert these functions. This was confirmed by expressing wild-type Cyt1 and Cyt2 tails and uncleavable mutant tails in primary T cells. The role of CD46 tails was also demonstrated with T cells expressing CD19 ectodomain-CD46 C-Terminal Fragment (CTF) fusions, which allowed specific triggering of each tail individually.We conclude that CD46 acts as a molecular rheostat to control human T cell activation through the regulation of processing of its cytoplasmic tails

Early rheumatoid arthritis is characterized by a distinct and transient synovial fluid cytokine profile of T cell and stromal cell origin

Pathological processes involved in the initiation of rheumatoid synovitis remain unclear. We undertook the present study to identify immune and stromal processes that are present soon after the clinical onset of rheumatoid arthritis ( RA) by assessing a panel of T cell, macrophage, and stromal cell related cytokines and chemokines in the synovial fluid of patients with early synovitis. Synovial fluid was aspirated from inflamed joints of patients with inflammatory arthritis of duration 3 months or less, whose outcomes were subsequently determined by follow up. For comparison, synovial fluid was aspirated from patients with acute crystal arthritis, established RA and osteoarthritis. Rheumatoid factor activity was blocked in the synovial fluid samples, and a panel of 23 cytokines and chemokines measured using a multiplex based system. Patients with early inflammatory arthritis who subsequently developed RA had a distinct but transient synovial fluid cytokine profile. The levels of a range of T cell, macrophage and stromal cell related cytokines ( e. g. IL-2, IL-4, IL-13, IL-17, IL-15, basic fibroblast growth factor and epidermal growth factor) were significantly elevated in these patients within 3 months after symptom onset, as compared with early arthritis patients who did not develop RA. In addition, this profile was no longer present in established RA. In contrast, patients with non-rheumatoid persistent synovitis exhibited elevated levels of interferon-gamma at initiation. Early synovitis destined to develop into RA is thus characterized by a distinct and transient synovial fluid cytokine profile. The cytokines present in the early rheumatoid lesion suggest that this response is likely to influence the microenvironment required for persistent RA

Does maximising ball speed in cricket fast bowling necessitate higher ground reaction forces?

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Sports Sciences on 17th July 2015, available online: http://www.tandfonline.com/10.1080/02640414.2015.1069375.This study aimed to investigate whether high peak ground reaction forces and high average loading rates are necessary to bowl fast. Kinematic and kinetic bowling data were collected for 20 elite male fast bowlers. A moderate non-significant correlation was found between ball speed and peak vertical ground reaction force with faster bowlers tending to have lower peak vertical ground reaction force (r = −0.364, P = 0.114). Faster ball speeds were correlated with both lower average vertical and lower average horizontal loading rates (r = −0.452, P = 0.046 and r = −0.484, P = 0.031, respectively). A larger horizontal (braking) impulse was associated with a faster ball speed (r = 0.574, P = 0.008) and a larger plant angle of the front leg (measured from the vertical) at front foot contact was associated with a larger horizontal impulse (r = 0.706, P = 0.001). These findings suggest that there does not necessarily need to be a trade-off between maximum ball release speed and the forces exerted on fast bowlers (peak ground reaction forces and average loading rates). Furthermore, it appears that one of the key determinants of ball speed is the horizontal impulse generated at the ground over the period from front foot contact until ball release

Large-scale geo-facial image analysis

While face analysis from images is a well-studied area, little work has explored the dependence of facial appearance on the geographic location from which the image was captured. To fill this gap, we constructed GeoFaces, a large dataset of geotagged face images, and used it to examine the geo-dependence of facial features and attributes, such as ethnicity, gender, or the presence of facial hair. Our analysis illuminates the relationship between raw facial appearance, facial attributes, and geographic location, both globally and in selected major urban areas. Some of our experiments, and the resulting visualizations, confirm prior expectations, such as the predominance of ethnically Asian faces in Asia, while others highlight novel information that can be obtained with this type of analysis, such as the major city with the highest percentage of people with a mustache