The Challenges of Equestrian Arena Surfaces: The Unprecedented Use of a Raised Platform at the 2012 Olympic Games.

The design of equestrian arenas can be challenged by time constraints and specific restrictions at a venue but are nonetheless a critical element to the success and sustainability of equestrian sport. The equestrian arenas for the 2012 Olympic Games were an example of a temporary arena constructed on a raised platform and supported by struts, a design unprecedented for equestrian activities. This study assessed the developmental stages of the Olympic surfaces from 2011 to the actual event in 2012 and aimed to confirm that accelerations and forces experienced by horses were comparable to those on solid ground. Assessment took place at (1) the Olympic test event;(2) a developmental mock-up arena; and (3) the Olympic venue in 2012. A Clegg impact hammer measured peak vertical deceleration and an Orono Biomechanical Surface Tester quantified peak load and peak loading rate. General Linear Models using the arena's structural features as explanatory variables highlighted surface heterogeneity. Peak vertical deceleration (P < .0001) and peak load (P < .0001) were significantly higher and peak loading rate was significantly lower (P < .0001) following iterative testing and modifications to the arena. Data were comparable with surfaces on solid ground by the final testing at the 2012 Olympic Games. Findings highlighted the importance of testing surfaces throughout their development and demonstrated the impact that surface composition, time elapsed since installation, water management, and type of construction have on surface functional properties, with relevance to future temporary arena initiatives.

A sustainable structure for jockey injury data management for the North American horse racing industry.

Jockey injuries in North American racing are not well understood. The types and severity of injuries as well as exposure need to be better characterized in order to reduce risk. We consider existing data sources and the opportunity to combine this data with a new data collection effort to better understand and potentially reduce risk to riders. Using a two-phase approach, data appears to be available which would allow useful information on jockey injuries that could inform efforts for risk reduction quickly and with modest resources. Initial successes can help to develop support for a more comprehensive data collection and risk reduction program.

Use of an inertial measurement unit to assess the effect of forelimb lameness on three-dimensional hoof orientation in horses at a walk and trot.

OBJECTIVE: To determine intralimb orientation changes with an inertial measurement unit (IMU) in hooves of horses at a walk and trot after induction of weight-bearing single forelimb lameness and to determine whether hoof orientations are similar to baseline values following perineural anesthesia. ANIMALS: 6 clinically normal horses. PROCEDURES: 3-D hoof orientations were determined with an IMU mounted on the right forelimb hoof during baseline conditions, during 3 grades of lameness (induced by application of pressure to the sole), and after perineural anesthesia. Linear acceleration profiles were used to segment the stride into hoof breakover, stance, initial swing, terminal swing, and total swing phases. Intralimb data comparisons were made for each stride segment. A repeated-measures mixed-model ANOVA was used for data analysis. RESULTS: Lameness resulted in significant changes in hoof orientation in all planes of rotation. A significant increase in external rotation and abduction and a significant decrease in sagittal plane rotation of the hoof were detected at hoof breakover during lameness conditions. For sagittal plane orientation data, the SDs determined following perineural anesthesia were higher than the SDs for baseline and lameness conditions. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study indicated the IMU could be used to detect 3-D hoof orientation changes following induction of mild lameness at a walk and trot. An increase in data variability for a sagittal orientation may be useful for assessment of local anesthesia for hooves. The IMU should be further evaluated for use in clinical evaluation of forelimb lameness in horses.

The effect of two preparation procedures on an equine arena surface in relation to motion of the hoof and metacarpophalangeal joint.

A link between surface characteristics and injury has been identified in equine disciplines. Maintenance procedures are reported to affect surface characteristics and could influence horse movement. The study investigated limb and hoof movement on a synthetic surface following two different preparations (harrowing and rolling). Nine horses were recorded using infrared cameras and retro-reflective markers at walk, trot and canter on two surface preparations in a cross-over design. Hoof rotation and displacement, metacarpophalangeal joint (MCPJ) extension and third metacarpal (McIII) inclination (roll, pitch and yaw) were analysed using a general linear model. Surface hardness and traction were also measured. No differences in hoof rotations or hoof displacements were found between preparations. However, following harrowing, greater (P<0.05) MCPJ extension at mid-stance and greater (P<0.05) McIII adduction at impact was found when gait was grouped. Hardness and traction were statistically similar for both preparations. Alteration to the surface cushion appears to be sufficient to produce subtle changes in stride characteristics.

Effect of forelimb lameness on hoof kinematics of horses at a trot.

OBJECTIVE: To determine kinematic changes to the hoof of horses at a trot after induction of unilateral, weight-bearing forelimb lameness and to determine whether hoof kinematics return to prelameness values after perineural anesthesia. ANIMALS: 6 clinically normal Quarter Horses. PROCEDURES: For each horse, a sole-pressure model was used to induce 3 grades (grades 1, 2, and 3) of lameness in the right forelimb, after which perineural anesthesia was administered to alleviate lameness. Optical kinematics were obtained for both forelimbs with the horse trotting before (baseline) and after induction of each grade of lameness and after perineural anesthesia. Hoof events were identified with linear acceleration profiles, and each stride was divided into hoof-contact, break-over, initial-swing, terminal-swing, and total-swing segments. For each segment, kinematic variables were compared within and between limbs by use of mixed repeated-measures ANOVA. RESULTS: During hoof-contact, the left (nonlame) forelimb hoof had greater heel-down orientation than did the right (lame) forelimb hoof, and during break-over, the nonlame hoof went through a larger range of motion than did the lame hoof. Maximum cranial acceleration during break-over for the lame hoof was greater, compared with that at baseline or for the nonlame hoof. Following perineural anesthesia, the sagittal plane orientation of the hoof during hoof-contact did not vary between the lame and nonlame limbs; however, interlimb differences in maximum cranial acceleration and angular range of motion during break-over remained. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that hoof kinematics may be useful for detection of unilateral, weight-bearing forelimb lameness in horses that are trotting.

Effect of forelimb lameness on hoof kinematics of horses at a walk.

OBJECTIVE: To determine kinematic changes to the hoof of horses at a walk after induction of unilateral, weight-bearing forelimb lameness and to determine whether hoof kinematics return to prelameness (baseline) values after perineural anesthesia. ANIMALS: 6 clinically normal Quarter Horses. PROCEDURES: For each horse, a sole-pressure model was used to induce 3 grades of lameness in the right forelimb, after which perineural anesthesia was administered to eliminate lameness. Optical kinematics were obtained for both forelimbs with the horse walking before (baseline) and after induction of each grade of lameness and after perineural anesthesia. Linear acceleration profiles were used to identify hoof events, and each stride was divided into hoof-contact, break-over, initial-swing, terminal-swing, and total-swing segments. Kinematic variables were compared within and between limbs for each segment by use of mixed repeated-measures ANOVA. RESULTS: During the hoof-contact and terminal-swing segments, the hoof of the left (nonlame) forelimb had greater sagittal-plane orientation than did the hoof of the right (lame) forelimb. For the lame limb following lameness induction, the break-over duration and maximum cranial acceleration were increased from baseline. After perineural anesthesia, break-over duration for the lame limb returned to a value similar to that at baseline, and orientation of the hoof during the terminal-swing segment did not differ between the lame and nonlame limbs. CONCLUSIONS AND CLINICAL RELEVANCE: Subclinical unilateral forelimb lameness resulted in significant alterations to hoof kinematics in horses that are walking, and the use of hoof kinematics may be beneficial for the detection of subclinical lameness in horses.

Hoof accelerations at hoof-surface impact for stride types and functional limb types relevant to show jumping horses.

Increased knowledge of the influence of stride type on hoof impact accelerations for fore and hind limbs could lead to a more complete picture of hoof-ground interactions in equine athletes. Hoof accelerations were quantified for each hoof of five show jumping horses using two orthogonal single axis ± 250 g accelerometers. Accelerations were recorded when cantering horses jumped fences of varying types (upright and oxer) and heights (90-130 cm) on three different surface conditions. Strides were identified as normal canter strides, take-off strides and landing strides. Descriptive hoof impact parameters were maximal vertical deceleration (MaZ), range of maximum fore-aft acceleration and deceleration (RaX), quotient of acceleration vectors (arctangent for RaX/MaZ) and hoof breaking duration (time from MaZ to first level of <0.042 g absolute fore-aft acceleration). The highest hoof impact accelerations occurred during the take-off stride (mean MaZ over limbs 52.6-91.6 g vs. all-stride mean 39.8 g; mean RaX 63.9-80.5 g vs. all-stride mean 50.7 g). At the jump landing, the forelimbs also experienced high MaZ (46.8 and 49.0 g) of the same order of magnitude as the forelimbs at the take-off. Non-lead limbs had higher MaZ in the normal canter stride, comparing within forelimb and hind limb pairs, and the reverse relationship occurred for RaX and for the quotient of acceleration vectors. The systematic variation introduced by limb and stride type suggests that these gait parameters are important to understand in a sport-specific context for horse surfaces, especially in the development of standardised testing equipment that simulates horse-surface interactions.

Radiated noise from commercial ships in the Gulf of Maine: implications for whale/vessel collisions.

To understand mysticete acoustic-based detection of ships, radiated noise from high-speed craft, cruise ships, catamarans and fishing vessels was recorded June-September 2009. Calibrated acoustic data (<2500 Hz) from a vertical hydrophone array was combined with ship passage information. A cruise ship had the highest broadband source level, while a fishing vessel had the lowest. Ship noise radiated asymmetrically and varied with depth. Bow null-effect acoustic shadow zones were observed for all ship classes and were correlated with ship-length-to-draft-ratios. These shadow zones may reduce ship detection by near-surface mysticetes.

AIDSVAX immunization induces HIV-specific CD8+ T-cell responses in high-risk, HIV-negative volunteers who subsequently acquire HIV infection.

Correlates of immune protection from HIV vaccines remain undefined. The first HIV vaccine efficacy trial in the US and Europe VAX004, was designed to assess whether rgp120 envelope subunits (AIDSVAX B/B, VaxGen) can induce partial or complete protection from HIV-1 infection. No effectiveness in the reduction of either the acquisition of infection or levels of plasma viremia after HIV infection was noted. We found evidence of vaccine-specific CD8+ T cells in volunteers who received the vaccine, regardless of behavioral risk. Surprisingly, the CD8-response is significantly higher in participants who would go on to contract HIV infection. These results suggest that AIDSVAX immunization may boost preexisting immune responses-due to pre-infection exposure, and a vaccine-induced immune profile may serve as a biological marker for HIV susceptibility.

Characterization of carbons derived from cellulose and lignin and their oxidative behavior.

In this study the oxidative behavior of carbons derived from cellulose and lignin were compared using thermogravimetric analysis (TGA). Specific surface area and chemical composition of the two types of carbon were analyzed using nitrogen adsorption at 77K and infrared spectroscopy respectively. The results demonstrate that cellulose carbon has a higher reaction order and lower activation energy than lignin carbon under identical experimental conditions when they were prepared at temperatures lower than 500 degrees C. However, such differences were considerably reduced for the carbon samples prepared at temperatures greater than 700 degrees C. It was verified that lignin carbon is more stable than cellulose carbon due to its higher content of aromatic structures when they are prepared at lower temperature. The specific surface area and porosity have a more limited contribution to the differential oxidative behaviors of the two types of carbon. This research has significance related to the formation of carbon nanotubes from plant materials during low temperature carbonization.

Biomechanical and mechanical investigations of the hoof-track interface in racing horses.

The aim of this article is to review current knowledge of kinetic variables of the hoof-track interaction and track properties relevant to the objective of minimizing injuries to horses at racing tracks. In each phase of the stance--primary impact, secondary impact, support, and breakover, the hoof experiences different combinations of force and acceleration. The role of each combination, and of measured track properties, in causing catastrophic and chronic injuries to the limbs of racing horses is unknown. Limited data of this type have been provided in previous epidemiologic studies of risk factors for breakdown. Future epidemiological studies should include characterization of the track surfaces and a more complete description of the kinematics of the hoof and surface. Consideration of an appropriate range of physical properties is necessary in track design, testing, and maintenance.

Comparison of HIV type 1 incidence observed during longitudinal follow-up with incidence estimated by cross-sectional analysis using the BED capture enzyme immunoassay.

The BED capture enzyme immunoassay (BED CEIA) for recent infection was developed for the estimation of HIV-1 incidence in a population from a single cross-sectional survey. To evaluate performance, we applied the assay to specimen sets obtained from a longitudinal cohort study, the AIDSVAX B/B vaccine trial, in which there was an independent and conventional measure of observed incidence. The BED CEIA was performed on specimens obtained during follow-up for seroconversion conducted every 6 months for 3 years. There was excellent agreement between the observed and BED-estimated incidence for all the intervals. The cumulative, annualized incidence observed in the cohort was 3.10 new infections per 100 person-years (95% CI, 2.57-3.63). The corresponding BED-estimated incidence was 2.91 (2.30-3.53). We also estimated the effect of varied prevalence on a fixed incidence. Because some specimens from persons with longer-term infection are classified as recent by the assay, this can inflate the incidence estimate. We quantify this effect and discuss potential mitigation by excluding certain specimens on clinical grounds, by relying on trend differences rather than absolute incidence estimates, by secondary confirmatory testing, or by analytic adjustments for misclassification. Cross-sectional HIV incidence estimation circumvents many of the drawbacks associated with longitudinal cohort studies, but there are test-specific limitations that should be considered in the design of population surveys.

Human immunodeficiency virus (HIV) vaccine trials: a novel assay for differential diagnosis of HIV infections in the face of vaccine-generated antibodies.

All current human immunodeficiency virus (HIV) vaccine candidates contain multiple viral components and elicit antibodies that react positively in licensed HIV diagnostic tests, which contain similar viral products. Thus, vaccine trial participants could be falsely diagnosed as infected with HIV. Additionally, uninfected, seropositive vaccinees may encounter long-term social and economic harms. Moreover, this also interferes with early detection of true HIV infections during preventive HIV vaccine trials. An HIV-seropositive test result among uninfected vaccine trial participants is a major public health concern for volunteers who want to participate in future HIV vaccine trials. Based on the increased number of HIV vaccines being tested globally, it is essential to differentiate vaccine- from virus-induced antibodies. Using a whole-HIV-genome phage display library, we identified conserved sequences in Env-gp41 and Gag-p6 which are recognized soon after infection, do not contain protective epitopes, and are not part of most current HIV vaccines. We established a new HIV serodetection assay based on these peptides. To date, this assay, termed HIV-SELECTEST, demonstrates >99% specificity and sensitivity. Importantly, in testing of plasma samples from multiple HIV vaccine trials, uninfected trial participants scored negative, while all intercurrent infections were detected within 1 to 3 months of HIV infection. The new HIV-SELECTEST is a simple but robust diagnostic tool for easy implementation in HIV vaccine trials and blood banks worldwide.

Correlation between immunologic responses to a recombinant glycoprotein 120 vaccine and incidence of HIV-1 infection in a phase 3 HIV-1 preventive vaccine trial.

BACKGROUND: An objective of the first efficacy trial of a candidate vaccine containing recombinant human immunodeficiency virus (HIV) type 1 envelope glycoprotein 120 (rgp120) antigens was to assess correlations between antibody responses to rgp120 and the incidence of HIV-1 infection. METHODS: Within the randomized trial (for vaccinees, n=3598; for placebo recipients, n=1805), binding and neutralizing antibody responses to rgp120 were quantitated. A case-cohort design was used to study correlations between antibody levels and HIV-1 incidence. RESULTS: Peak antibody levels were significantly inversely correlated with HIV-1 incidence. The relative risk (RR) of infection was 0.63 (95% confidence interval, 0.45-0.89) per log(10) higher neutralization titer against HIV-1(MN), and the RRs of infection for second-, third-, and fourth-quartile responses of antibody blocking of gp120 binding to soluble CD4 versus first-quartile responses (the lowest responses) were 0.35, 0.28, and 0.22, respectively. CONCLUSIONS: Despite inducing a complex, robust immune response, the vaccine was unable to reduce the incidence of HIV-1. Two interpretations of the correlative results are that the levels of antibodies (i) caused both an increased (low responders) and decreased (high responders) risk of HIV-1 acquisition or (ii) represented a correlate of susceptibility to HIV-1 but had no causal effect on susceptibility. Although the data cannot definitively discriminate between these 2 explanations, (ii) appears to be more likely.

Phase I/II study of a candidate vaccine designed against the B and E subtypes of HIV-1.

A phase I/II trial of a candidate vaccine to prevent HIV infection was carried out in Bangkok, Thailand, testing AIDSVAX B/E (VaxGen, Inc., Brisbane, CA), a bivalent subunit vaccine prepared by combining recombinant gp120 from a subtype B virus (HIV-1MN) with gp120 from a subtype E virus (HIV-1A244) in alum adjuvant. The studies provide human data on the immunogenicity of various dose combination of non-subtype B vaccine antigens. The results suggest that AIDSVAX B/E is safe and immunogenic in humans. The optimal dose for humans in developing countries was 300 microg of each antigen (B and E). Clade E responses were measurably increased by immunizing with gp120 B/E over B alone. Using the B/E combination did not interfere with the response to either clade. Antibodies to AIDSVAX B/E were able to bind to oligomeric gp120 on the surface of cells infected with primary isolates of HIV-1.

Knee loads in the standard and recumbent cycling positions.

The recumbent cycling position (RCP) has become increasingly popular in recent years as a mode of exercise and rehabilitation. However, subtle, but important, differences are expected to exist between the RCP and the standard, upright cycling position (SCP). The differences are due primarily to the altered orientation of the rider's lower extremities relative to gravity. In order to determine if one cycling position may be preferential to another for certain types of rehabilitation, knee loads from a planar, inverse-dynamics model were examined. Nineteen recreational cyclists (24.6 +/- 4.2 yrs) were acclimated to recumbent cycling prior to measuring kinetics and kinematics in both a RCP and SCP (90 rpm; 250 W; max hip-to-pedal distance = 105% leg length). Significance was set at p [symbol: see text] 0.01. Lower-extremity kinematics were not different between the two positions, suggesting that muscle, ligament, and supporting structures travel through the same ranges of motion in both forms of cycling. However, the anterior/posterior forces were altered in such a way that the magnitude of the forces tending to displace the tibia anterior relative to the femur were significantly reduced in the RCP, suggesting that less load may be placed on the anterior cruciate ligament (ACL) while recumbent cycling. No changes in the tension/compression forces were observed at the knee, suggesting no differences in knee stability resulting from compressive forces between the tibia and femur. These findings indicate that the RCP may be beneficial when attempting to minimize ACL loads while utilizing cycling as an exercise and rehabilitative modality.