919 research outputs found
Analysis of repeated high-intensity running performance in professional soccer
The aims of this study conducted in a professional soccer team were two-fold: to characterise repeated high-intensity movement activity profiles in official match-play; b) to inform and verify the construct validity of tests commonly used to determine repeated-sprint ability in soccer by investigating the relationship between the results from a test of repeated-sprint ability and repeated high-intensity performance in competition. High-intensity running performance (movement at velocities >19.8 km/h for a minimum of 1-s duration) in 20 players was measured using computerised time motion analysis. Performance in 80 French League 1 matches was analysed. In addition, 12 out of the 20 players performed a repeated-sprint test on a non-motorized treadmill consisting of 6 consecutive 6s sprints separated by 20s passive recovery intervals. In all players, the majority of consecutive high-intensity actions in competition were performed after recovery durations ≥61s, recovery activity separating these efforts was generally active in nature with the major part of this spent walking, and players performed 1.1±1.1 repeated high-intensity bouts (a minimum of 3 consecutive high-intensity with a mean recovery time ≤20s separating efforts) per game. Players reporting lowest performance decrements in the repeated-sprint ability test performed more high-intensity actions interspersed by short recovery times (≤20s, p<0.01 and ≤30s, p<0.05) compared to those with higher decrements. Across positional roles, central-midfielders performed a greater number of high-intensity actions separated by short recovery times (≤20s) and spent a larger proportion of time running at higher intensities during recovery periods while fullbacks performed the most repeated high-intensity bouts (statistical differences across positional roles from p<0.05 to p<0.001). These findings have implications for repeated high-intensity testing and physical conditioning regimens
APOE genotype and cognition in healthy individuals at risk of Alzheimer's disease: A review
APOE-\u3b54 is best known as a risk factor for Alzheimer's disease (AD). Consequently, there is considerable research interest in understanding whether APOE-\u3b54 influences cognition in healthy adults. Despite a substantial literature reporting effects of APOE genotype on cognition, findings are inconsistent. In particular, it is challenging to separate whether cognitive deficits in APOE-\u3b54 carriers reflect the influence of prodromal dementia pathology (\u201cprodromal hypothesis\u201d), or a direct contribution of APOE genotype to individual differences (\u201cphenotype hypothesis\u201d). Variable methodology across studies further complicates the issue. These challenges have limited what can be learnt about the processes underlying cognitive ageing and dementia by studying the influence of APOE genotype on cognition. In this review, we focus on the two compatible neurobiological mechanisms by which APOE genotype may influence cognition in healthy adults (prodromal and phenotype). We summarise the behavioural evidence for the influence of APOE on cognition in non-demented adults and explore key methodological challenges for disentangling the cognitive effects of different neurobiological mechanisms of APOE. Evidence suggests that at least some APOE-\u3b54 cognitive deficits are due to early AD pathology, whilst sensitive measures of cognition are beginning to reveal subtle cognitive differences between APOE genotypes in mid-adulthood, prior to the onset of the AD prodromal period. We conclude with recommendations for future research to investigate the cognitive consequences of neurobiological processes affected by APOE and maximise the translational potential of this research
The Proportion of Women Who Have a Breast 4 Years after Breast Cancer Surgery: A Population-Based Cohort Study.
BACKGROUND: There are numerous pathways in breast cancer treatment, many of which enable women to retain a breast after treatment. We evaluated the proportion of women who have a breast, either through conserving surgery (BCS) or reconstruction, at 4-years after diagnosis, and how this varied by patient group. METHODS AND FINDINGS: We identified women with breast cancer who underwent initial BCS or mastectomy in English National Health Service (NHS) hospitals between January 2008 and December 2009 using the Hospital Episode Statistics (HES) database. Women were assigned into one of four patient groups depending on their age at diagnosis and presence of comorbidities. The series of breast cancer procedure (BCS, mastectomy, immediate, or delayed reconstruction) undergone by each women was identified over four years, and the proportion of women with a breast calculated. Variation was examined across patient groups, and English Cancer Networks. Between 2008 and 2009, 60,959 women underwent BCS or mastectomy. The proportion with a breast at 4 years was 79.3%, and 64.0%, in women less than 70 years without, and with comorbidities. Whilst in women aged 70 and over without, and with comorbidities, proportions were 52.6%, and 38.2%, respectively. Comorbidities were associated with lower proportions of BCS, but had little effect on reconstruction rates unlike age. Networks variation of 15% or more was found within each patient group, and Cancer Networks tended to have either a high or low proportion across all four patient groups. However, while 14% of women under 70 years had undergone reconstruction, less than 2% of women aged 70 or more had this treatment option. CONCLUSION: The proportion of women diagnosed with breast cancer who retain a breast at 4 years is strongly associated with age, and presence of comorbidities. There was significant variation between Cancer Networks indicating that women's experience in England was dependent on their geographical location of treatment
Discovery of a new cataclysmic variable through optical variability and X-ray emission
Aims: We present discovery observations of the new cataclysmic variable star
(CV) 1RXS J092737.4-191529, as well as spectra and photometry of SY Vol. The
selection technique that turned up these two CVs is described; it should be
efficient for finding dwarf novae with high outburst duty cycles. Methods: Two
very common observational features of CVs, namely optical variability and X-ray
emission, are combined to select targets for follow-up observations. Long-slit
spectra were taken to identify CVs in the sample. Results: Two out of three
objects selected in this way are CVs. One of these is the known dwarf nova SY
Vol, while the second system, 1RXS J092737.4-191529, is a new discovery. We
present medium resolution spectra, magnitudes, and high-speed
photometry for both these CVs. Rapid flickering in the light curve of 1RXS
J092737.4-191529 confirms the mass transferring binary nature of this object;
it is probably a dwarf nova that was in quiescence during our observations.Comment: 4 pages, 5 figures, accepted to A&
Rate and equilibrium constants for the addition of triazolium salt derived N-heterocyclic carbenes to heteroaromatic aldehydes
Heteroaromatic aldehydes are often used preferentially or exclusively in a range of NHC-catalysed processes that proceed through the generation of a reactive diaminoenol or Breslow Intermediate (BI), with the reason for their unique reactivity currently underexplored. This manuscript reports measurement of rate and equilibrium constants for the reaction between N-aryl triazolium NHCs and heteroaromatic aldehydes, providing insight into the effect of the NHC and heteroaromatic aldehyde structure up to formation of the BI. Variation in NHC catalyst and heteroaromatic aldehyde structure markedly affect the observed kinetic parameters of adduct formation, decay to starting materials and onward reaction to BI. In particular, large effects are observed with both 3-halogen (Br, F) and 3-methyl substituted pyridine-2-carboxaldehyde derivatives which substantially favour formation of the tetrahedral intermediate relative to benzaldehyde derivatives. Key observations indicate that increased steric hindrance leads to a reduction in both k2 and k−1 for large (2,6-disubstituted)-N-Ar groups within the triazolium scaffold, and sterically demanding aldehyde substituents in the 3-position, but not in the 6-position of the pyridine-2-carboxaldehyde derivatives. As part of this study, the isolation and characterisation of twenty tetrahedral adducts formed upon addition of N-aryl triazolium derived NHCs into heteroaromatic aldehydes are described. These adducts are key intermediates in NHC-catalysed umpolung addition of heteroaromatic aldehydes and are BI precursors
Biochar Carbon stability in some contrasting soils from Australia
Climate change is one of the biggest challenges facing the world. The largest contributor to climate change is the greenhouse gas CO2, which is released through anthropogenic activities such as burning of fossil fuel and agricultural waste. To find solutions to mitigate climate change, research has been proposed to reduce greenhouse gas emissions or off-setting emissions through carbon (C) sequestration in soil − the largest C pool of terrestrial ecosystems. In this context, long-term C storage through biochar application to agricultural soils has been becoming a priority area of research in the last two decades
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