121 research outputs found

    Distribution and Trends of Endemic Hawaiian Waterbirds

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    Four endemic species of wetland-dependent waterbirds occur on the main Hawaiian Islands, all of which have experienced sharp population declines and are listed as endangered species. Twice per year, state-wide surveys are conducted to count waterbirds, but these surveys are evaluated only infrequently. We used a state-space approach to evaluate long-term (1986–2016) and short-term (2006–2016) trends and current distribution and abundance of endemic Hawaiian waterbirds. The most numerous species was the Ae‘o, or Hawaiian Stilt (Himantopus mexicanus knudseni), with a 5-year estimated average abundance of 1,932 individuals, followed by ‘Alae Ke‘oke‘o, or Hawaiian Coot (Fulica alai), with 1,815 individuals, Alae ‘Ula, or Hawaiian Common Gallinule (Gallinula galeata sandvicensis) with 927 individuals, and the Koloa Maoli, or Hawaiian Duck (Anas wyvilliana) with 931 individuals. All four species had positive trends over the long-term, but short-term and island specific trends were more variable, and in some cases negative. These results provide valuable information to help guide management of Hawaii’s threatened and endangered endemic waterbirds

    Laterally Propagating Detonations in Thin Helium Layers on Accreting White Dwarfs

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    Theoretical work has shown that intermediate mass (0.01Msun<M_He<0.1Msun) Helium shells will unstably ignite on the accreting white dwarf (WD) in an AM CVn binary. For more massive (M>0.8Msun) WDs, these helium shells can be dense enough (5x10^5 g/cc) that the convectively burning region runs away on a timescale comparable to the sound travel time across the shell; raising the possibility for an explosive outcome. The nature of the explosion (i.e. deflagration or detonation) remains ambiguous. In the case of detonation, this causes a laterally propagating front whose properties in these geometrically thin and low density shells we begin to study here. Our calculations show that the radial expansion time of <0.1 s leads to incomplete helium burning, in agreement with recent work by Sim and collaborators, but that the nuclear energy released is still adequate to realize a self-sustaining detonation propagating laterally at slower than the Chapman-Jouguet speed. Our simulations resolve the subsonic region behind the front and are consistent with a direct computation of the reaction structure from the shock strength. The ashes are typically He rich, and consist of predominantly Ti-44, Cr-48, along with a small amount of Fe-52, with very little Ni-56 and with significant Ca-40 in carbon-enriched layers. If this helium detonation results in a Type Ia Supernova, its spectral signatures would appear for the first few days after explosion. (abridged)Comment: 7 pages, 5 figure, accepted to the Astrophysical Journa

    Effects of Small-Sided Games vs. Conventional Endurance Training on Endurance Performance in Male Youth Soccer Players: A Meta-Analytical Comparison

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    This paper is in closed access .© 2019, Springer Nature Switzerland AG. Background: Small-sided games have been suggested as a viable alternative to conventional endurance training to enhance endurance performance in youth soccer players. This has important implications for long-term athlete development because it suggests that players can increase aerobic endurance through activities that closely resemble their sport of choice. Objectives: The objectives of this meta-analysis were to compare male youth soccer players’ adaptability to small-sided games vs. conventional endurance training and to establish exercise prescription guidelines for this population. Data Sources: The data sources utilised were Google Scholar, PubMed and Microsoft Academic. Study Eligibility Criteria: Studies were eligible for inclusion if interventions were carried out in male soccer players (aged < 18 years) and compared the effects of small-sided games and conventional endurance training on aerobic endurance performance. We defined small-sided games as “modified [soccer] games played on reduced pitch areas, often using adapted rules and involving a smaller number of players than traditional games”. We defined conventional endurance training as continuous running or extensive interval training consisting of work durations > 3 min. Study Appraisal and Synthesis Methods: The inverse-variance random-effects model for meta-analyses was used because it allocates a proportionate weight to trials based on the size of their individual standard errors and facilitates analysis whilst accounting for heterogeneity across studies. Effect sizes were represented by the standardised mean difference and presented alongside 95% confidence intervals. Results: Seven studies were included in this meta-analysis. Both modes of training were effective in increasing endurance performance. Within-mode effect sizes were both of moderate magnitude [small-sided games: 0.82 (95% confidence interval 0.05, 1.60), Z = 2.07 (p = 0.04); conventional endurance training: 0.89 (95% confidence interval 0.06, 1.72), Z = 2.10 (p = 0.04)]. There were only trivial differences [0.04 (95% confidence interval − 0.36, 0.43), Z = 0.18 (p = 0.86)] between the effects on aerobic endurance performance of small-sided games and conventional endurance training. Subgroup analyses showed mostly trivial differences between the training methods across key programming variables such as set duration (≄ or < 4 min) and recovery period between sets (≄ or < 3 min). Programmes that were longer than 8 weeks favoured small-sided games [effect size = 0.45 (95% confidence interval − 0.12, 1.02), Z = 1.54 (p = 0.12)], with the opposite being true for conventional endurance training [effect size = − 0.33 (95% confidence interval − 0.79, 0.14), Z = 1.39 (p = 0.16)]. Programmes with more than 4 sets per session favoured small-sided games [effect size = 0.53 (95% confidence interval − 0.52, 1.58), Z = 0.98 (p = 0.33)] with only a trivial difference between those with 4, or fewer, sets [effect size = − 0.13 (95% confidence interval − 0.52, 0.26), Z = 0.65 (p = 0.52)]. Conclusions: Small-sided games are as effective as conventional endurance training for increasing aerobic endurance performance in male youth soccer players. This is important for practitioners as it means that small-sided games can allow both endurance and skills training to be carried out simultaneously, thus providing a more efficient training stimulus. Small-sided games offer the same benefits as conventional endurance training with two sessions per week, with ≄ 4 sets of 4 min of activity, interspersed with recovery periods of 3 min, recommended in this population

    Effects of small-sided games vs. conventional endurance training on endurance performance in male youth soccer players: A meta-analytical comparison

    Get PDF
    Background: Small-sided games have been suggested as a viable alternative to conventional endurance training to enhance endurance performance in youth soccer players. This has important implications for long-term athlete development because it suggests that players can increase aerobic endurance through activities that closely resemble their sport of choice. Objectives: The objectives of this meta-analysis were to compare male youth soccer players’ adaptability to small-sided games vs. conventional endurance training and to establish exercise prescription guidelines for this population. Data Sources: The data sources utilised were Google Scholar, PubMed and Microsoft Academic. Study Eligibility Criteria: Studies were eligible for inclusion if interventions were carried out in male soccer players (aged 3 min. Study Appraisal and Synthesis Methods: The inverse-variance random-effects model for meta-analyses was used because it allocates a proportionate weight to trials based on the size of their individual standard errors and facilitates analysis whilst accounting for heterogeneity across studies. Effect sizes were represented by the standardised mean difference and presented alongside 95% confidence intervals. Results: Seven studies were included in this meta-analysis. Both modes of training were effective in increasing endurance performance. Within-mode effect sizes were both of moderate magnitude [small-sided games: 0.82 (95% confidence interval 0.05, 1.60), Z = 2.07 (p = 0.04); conventional endurance training: 0.89 (95% confidence interval 0.06, 1.72), Z = 2.10 (p = 0.04)]. There were only trivial differences [0.04 (95% confidence interval − 0.36, 0.43), Z = 0.18 (p = 0.86)] between the effects on aerobic endurance performance of small-sided games and conventional endurance training. Subgroup analyses showed mostly trivial differences between the training methods across key programming variables such as set duration (≄ or < 4 min) and recovery period between sets (≄ or < 3 min). Programmes that were longer than 8 weeks favoured small-sided games [effect size = 0.45 (95% confidence interval − 0.12, 1.02), Z = 1.54 (p = 0.12)], with the opposite being true for conventional endurance training [effect size = − 0.33 (95% confidence interval − 0.79, 0.14), Z = 1.39 (p = 0.16)]. Programmes with more than 4 sets per session favoured small-sided games [effect size = 0.53 (95% confidence interval − 0.52, 1.58), Z = 0.98 (p = 0.33)] with only a trivial difference between those with 4, or fewer, sets [effect size = − 0.13 (95% confidence interval − 0.52, 0.26), Z = 0.65 (p = 0.52)]. Conclusions: Small-sided games are as effective as conventional endurance training for increasing aerobic endurance performance in male youth soccer players. This is important for practitioners as it means that small-sided games can allow both endurance and skills training to be carried out simultaneously, thus providing a more efficient training stimulus. Small-sided games offer the same benefits as conventional endurance training with two sessions per week, with ≄ 4 sets of 4 min of activity, interspersed with recovery periods of 3 min, recommended in this population

    Deletion of Panx3 Prevents the Development of Surgically Induced Osteoarthritis

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    © 2015, Springer-Verlag Berlin Heidelberg. Abstract: Osteoarthritis (OA) is a highly prevalent, disabling joint disease with no existing therapies to slow or halt its progression. Cartilage degeneration hallmarks OA pathogenesis, and pannexin 3 (Panx3), a member of a novel family of channel proteins, is upregulated during this process. The function of Panx3 remains poorly understood, but we consistently observed a strong increase in Panx3 immunostaining in OA lesions in both mice and humans. Here, we developed and characterized the first global and conditional Panx3 knockout mice to investigate the role of Panx3 in OA. Interestingly, global Panx3 deletion produced no overt phenotype and had no obvious effect on early skeletal development. Mice lacking Panx3 specifically in the cartilage and global Panx3 knockout mice were markedly resistant to the development of OA following destabilization of medial meniscus surgery. These data indicate a specific catabolic role of Panx3 in articular cartilage and identify Panx3 as a potential therapeutic target for OA. Lastly, while Panx1 has been linked to over a dozen human pathologies, this is the first in vivo evidence for a role of Panx3 in disease. Key message: Panx3 is localized to cartilage lesions in mice and humans.Global Panx3 deletion does not result in any developmental abnormalities.Mice lacking Panx3 are resistant to the development of osteoarthritis.Panx3 is a novel therapeutic target for the treatment of osteoarthritis

    Comparison of Asymmetric Reaming versus a Posteriorly Augmented Component for Posterior Glenoid Wear and Retroversion: A Radiographic Study.

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    Background: Managing posterior glenoid wear and retroversion remains a challenge in shoulder arthroplasty. Correcting glenoid version through asymmetric reaming (AR) with placement of a standard glenoid component and the use of posteriorly augmented glenoid (PAG) components are two methods used to address this problem. Our objective is to report the radiographic outcomes of patients with posterior glenoid wear and/or retroversion treated with either approach. Methods: Patients with posterior glenoid wear and a minimum of 15 degrees of retroversion, treated with AR and standard glenoid component or with a PAG component (3 mm, 5 mm, or 7 mm posterior augmentation), were consecutively identified through retrospective chart review. Pre-operative axillary views were evaluated for version, humeral head subluxation in relation to scapular axis and to mid-glenoid face. Post-operative axillary views were reviewed to measure corrected inversion and humeral head subluxation. Results: There were 48 patients in the AR group and 49 patients in the PAG group. Version improved 6.8 degrees in the AR group. In the PAG group, version improved 8.8 degrees with 3 mm augment, 13.4 degrees with 5 mm augment, and 12.8 with 7 mm augments. There were significantly more central peg perforations in the 5 mm PAG group compared to other groups. The humeral head was re-centered within 6.1% of normal in all groups except 7 mm augments. Conclusion: This study demonstrates that AR and PAGs have the ability to re-center the humeral head when utilized in patients with retroversion and posterior wear. Use of a PAG component may allow for greater correction of glenoid retroversion, however, there is an increased risk for central peg perforation with the specific implant utilized in this study. Long-term follow-up is ongoing and needed to understand the clinical implications of these findings

    Variable long-term developmental trajectories of short sprint speed and jumping height in English Premier League academy soccer players: an applied case study

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    Growth and maturation can affect physical performance over the long term, making the appraisal of athletic ability difficult. Using a previously published method, we sought to longitudinally track youth soccer players to assess the developmental trajectory of athletic performance over a six-year period in an English Premier League academy. Age-specific z-scores were calculated for sprint and jump performance from a sample of male youth soccer players (n = 140). A case study approach was used to analyse the longitudinal curves of the six players with the longest tenure. A regression equation for each fitness variable facilitated comparison of participants to the wider sample. The trajectories of the sprint times of players 1 and 3 were characterised by a marked difference in respective performance levels up until peak height velocity (PHV) when player 1 achieved a substantial increase in sprint speed and player 3 experienced a large decrease. Player 5 was consistently a better performer than player 2 until PHV when the sprint and jump performance of the former markedly decreased and he was overtaken by the latter. Fluctuations in players’ physical performance can occur quickly and in drastic fashion. Coaches must be aware that suppressed, or inflated, performance could be temporary and selection and deselection decisions should not be made based on information gathered over a short time period

    Planning for pre-exposure prophylaxis to prevent HIV transmission: challenges and opportunities

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    There are currently several ongoing or planned trials evaluating the efficacy of pre-exposure prophylaxis (PrEP) as a preventative approach to reducing the transmission of HIV. PrEP may prove ineffective, demonstrate partial efficacy, or show high efficacy and have the potential to reduce HIV infection in a significant way. However, in addition to the trial results, it is important that issues related to delivery, implementation and further research are also discussed. As a part of the ongoing discussion, in June 2009, the Bill & Melinda Gates Foundation sponsored a Planning for PrEP conference with stakeholders to review expected trial results, outline responsible educational approaches, and develop potential delivery and implementation strategies. The conference reinforced the need for continued and sustained dialogue to identify where PrEP implementation may fit best within an integrated HIV prevention package. This paper identifies the key action points that emerged from the Planning for PrEP meeting
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