223 research outputs found

    The Effect of Fatigue on Shoulder Muscle Strength Ratios in Collegiate Water Polo Players

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    Introduction: A proposed mechanism of shoulder injuries is imbalances in the strength of the shoulder muscles, however, the effects of fatigue on these imbalances are unknown. The purpose of this study was to investigate the relationship of isokinetic-induced fatigue on the development of shoulder muscle imbalances using both the conventional and functional ratio

    Relationship between Ground Reaction Force Characteristics and Bone Mineral Density of the Hip and Spine in Male Runners

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    International Journal of Exercise Science 15(1): 655-666, 2022. The purpose of this study was to determine the relationship between running ground reaction force (GRF) characteristics and hip and lumbar spine bone mineral density (BMD) values in male runners. Individuals who ran at least 48.3 km per week and were injury-free were recruited. Kistler force plates collected running vertical and anteroposterior GRF data. A Hologic Discovery W bone densitometer measured lumbar spine and five regional hip BMD values. Only runners who consistently used a rear foot strike pattern were included (n = 32). Pearson correlation coefficients were calculated between BMD values and various GRF values and step-wise multiple regression was run to predict BMD values from the various GRF values. The vertical impact force was significantly correlated with the lumbar spine and four of the five hip BMD values (r \u3e 0.374, p \u3c 0.035). Both the peak early loading rate (ELR) and average ELR were significantly correlated with the lumbar spine and Ward’s triangle BMD (r \u3e 0.430, p \u3c 0.014), while the average active loading rate was correlated only with the Ward’s triangle BMD (r = 0.438, p = 0.012). Multiple regression revealed the peak impact force was the predictor for every hip region BMD other than the trochanter and the average ELR as a predictor for the lumbar spine BMD. The peak braking force was negatively correlated with the Ward’s triangle BMD (r = - 0.414, p = 0.019). It appears that the large forces and loading rates associated with rear foot striking may be advantageous and predictive for BMD at the hip and spine

    Chirp subbottom profiler for quantitative sediment analysis

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    A wide‐band, frequency‐modulated, subbottom profiling system (the chirp sonar) can remotely determine the acoustic attenuation of ocean sediments and produce artifact‐free sediment profiles in real time. The chirp sonar is controlled by a minicomputer which performs analog‐to‐digital and digital‐to‐analog conversion, correlation processing, and attenuation estimation in real time. The minicomputer generates an FM pulse that is phase‐ and amplitude‐compensated to correct for the sonar system response. Such precise waveform control helps suppress correlation noise and source ringing. The chirp sonar, which has an effective bandwidth of 5 kHz, can generate chirp (Klauder) wavelets with a tuning thickness (Rayleigh’s criterion for resolution) of approximately 0.1 ms. After each return is correlated, a computationally fast algorithm estimates the attenuation of subbottom reflections by waveform matching with a theoretically attenuated waveform. This algorithm obtains an attenuation estimate by minimizing the mean‐square error between the autocorrelation function of the theoretically attenuated wavelet and the autocorrelation function of the subbottom reflection. The chirp sonar was tested in Narragansett Bay, R.I. along a line that had been previously cored. Experimental results show that correlation noise from the seafloor reflection was below −60 dB, the quantization noise level, thereby allowing detection of small subbottom impedance contrasts and accurate estimation of attenuation. Attenuation coefficient estimates from this sandy region agree with in‐situ measurements made by other investigators

    ATXR5 and ATXR6 are H3K27 monomethyltransferases required for chromatin structure and gene silencing.

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    Constitutive heterochromatin in Arabidopsis thaliana is marked by repressive chromatin modifications, including DNA methylation, histone H3 dimethylation at Lys9 (H3K9me2) and monomethylation at Lys27 (H3K27me1). The enzymes catalyzing DNA methylation and H3K9me2 have been identified; alterations in these proteins lead to reactivation of silenced heterochromatic elements. The enzymes responsible for heterochromatic H3K27me1, in contrast, remain unknown. Here we show that the divergent SET-domain proteins ARABIDOPSIS TRITHORAX-RELATED PROTEIN 5 (ATXR5) and ATXR6 have H3K27 monomethyltransferase activity, and atxr5 atxr6 double mutants have reduced H3K27me1 in vivo and show partial heterochromatin decondensation. Mutations in atxr5 and atxr6 also lead to transcriptional activation of repressed heterochromatic elements. Notably, H3K9me2 and DNA methylation are unaffected in double mutants. These results indicate that ATXR5 and ATXR6 form a new class of H3K27 methyltransferases and that H3K27me1 represents a previously uncharacterized pathway required for transcriptional repression in Arabidopsis

    Report: Telepaediatrics in Rural and Remote Australia and Canada

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    Rural and remote communities in Australia and Canada experience barriers to accessing healthcare services (1). These barriers are especially pronounced when attempting to access more specialized health care services, such as paediatric (2–4). Both countries have implemented programs that aim to bridge the gap between rural communities and specialized healthcare. One such service is telepaediatrics. Telepaediatrics, as part of telehealth, refers to any paediatric health-related service, network, or medical tool that transmits voice, data, images and information through telecommunication programs as part of providing health services (5–7). Telehealth services are ideal because they remove the need to relocate the rural patient to urban specialist sites (5–7). In a WHO survey (2010), 60% of member countries had telehealth services in place but only 30% of these programs were implemented as part of routin

    Population Growth, Carrying Capacity, and Conflict

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    Effects of increased pCO2 and temperature on the North Atlantic spring bloom. III. Dimethylsulfoniopropionate

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    The CLAW hypothesis argues that a negative feedback mechanism involving phytoplankton- derived dimethylsulfoniopropionate (DMSP) could mitigate increasing sea surface temperatures that result from global warming. DMSP is converted to the climatically active dimethylsulfide (DMS), which is transferred to the atmosphere and photochemically oxidized to sulfate aerosols, leading to increases in planetary albedo and cooling of the Earth’s atmosphere. A shipboard incubation experiment was conducted to investigate the effects of increased temperature and pCO2 on the algal community structure of the North Atlantic spring bloom and their subsequent impact on particulate and dissolved DMSP concentrations (DMSPp and DMSPd). Under ‘greenhouse’ conditions (elevated pCO2; 690 ppm) and elevated temperature (ambient + 4°C), coccolithophorid and pelagophyte abundances were significantly higher than under control conditions (390 ppm CO2 and ambient temperature). This shift in phytoplankton community structure also resulted in an increase in DMSPp concentrations and DMSPp:chl a ratios. There were also increases in DMSP-lyase activity and biomass-normalized DMSP-lyase activity under ‘greenhouse’ conditions. Concentrations of DMSPd decreased in the ‘greenhouse’ treatment relative to the control. This decline is thought to be partly due to changes in the microzooplankton community structure and decreased grazing pressure under ‘greenhouse’ conditions. The increases in DMSPp in the high temperature and greenhouse treatments support the CLAW hypothesis; the declines in DMSPd do not

    Inflammatory Markers and Risk of Hip Fracture in Older White Women: The Study of Osteoporotic Fractures †

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    Abstract Hip fractures are the most devastating consequence of osteoporosis and impact 1 in 6 white women leading to a 2-3 fold increased mortality risk in the first year. Despite evidence of inflammatory markers in the pathogenesis of osteoporosis, few studies have examined their effect on hip fracture. To determine if high levels of inflammation increase hip fracture risk and explore mediation pathways, a case-cohort design nested in a cohort of 4709 white women from the Study of Osteoporotic Fractures was used. A random sample of 1171 women was selected as the subcohort (mean age 80.1 ± 4.2 years) plus the first 300 women with incident hip fracture. Inflammatory markers interleukin-6 (IL-6) and soluble receptors (SR) for IL-6 (IL-6 SR) and tumor necrosis factor (TNF SR1 and TNF SR2) were measured and participants were followed for a median (interquartile range) of 6.3 (3.7, 6.9) years. In multivariable models, the hazard ratio (HR) of hip fracture for women in the highest inflammatory marker level (quartile 4) was 1.64 (95% confidence interval [CI], 1.09-2.48, p trend=0.03) for IL-6 and 2.05 (95% CI, 1.35-3.12, p trend <0.01) for TNF SR1 when compared with women in the lowest level (quartile 1). Among women with 2 and 3-4 inflammatory markers in the highest quartile, the HR of hip fracture was 1.51 (95% CI, 1.07-2.14) and 1.42 (95% CI, 0.87-2.31) compared with women with 0-1 marker(s) in the highest quartile (p trend = 0.03). After individually adjusting for 7 potential mediators, cystatin-C (a biomarker of renal function) and bone mineral density (BMD) attenuated HRs among women with the highest inflammatory burden by 20% and 15%, respectively, suggesting a potential mediating role. Older white women with high inflammatory burden are at increased risk of hip fracture in part due to poor renal function and low BMD
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