30 research outputs found
Mechanical spring technology improves running economy in endurance runners
In recent years there has been an increase in participation in timed running events. With this increase, the motivation for individuals to run their best has motivated the running shoe industry to make design changes to traditional running foot wear in an effort to improve running economy (RE) and decrease running times. One such design change has been to incorporate mechanical springs (MS) into the midsole of the running shoe. Evaluation of this technology has yet to be performed. This study recruited 17 runners (12 male) and had them run at a submaximal steady state speed for 2 bouts of five minutes at a speed of 3.13 m·sec-1. The order of shoe condition was randomly assigned and the subjects ran one interval in their own running shoe (OS) and one interval in MS shoes. Metabolic data and heart rate data were averaged over the last three of the five minute efforts. No significant difference was found between MS and OS with regards to shoe weight. Running in MS resulted in lower, non-significant values for steady state ventilation and steady state heart rate. Oxygen consumption was significantly lower in MS compared to OS in both absolute (MS: 2.35 ± 0.47 L·min-1 vs. OS: 2.40 ± 0.473 L·min-1, P=0.022) and relative (MS: 34.67 ± 4.35 ml·kg-1·min-1 vs. OS: 35.34 ± 4.58 ml·kg-1·min-1, P=0.033) terms. Running in shoes fitted with MS technology improves running economy over OS and this technology may assist athletes achieve their best running times
WMAP5 and the Cluster Mass Function
The recently revised cosmological constraints from the Five-Year WMAP data
ameliorate previous tension between cosmological constraints from the microwave
background and from cluster abundances. We demonstrate that the revised
estimates of cosmological parameters are in excellent agreement with the mass
function of X-ray clusters in the Sloan Digital Sky Survey. Velocity
segregation between galaxies and the underlying dark matter could cause virial
mass estimates to be biased, causing the mass scale of the mass function to be
offset from the true value. Modest velocity segregation
(=1.13) is sufficient to match the
mass function to the Five-Year WMAP results. When the new WMAP results are
combined with constraints from supernovae and baryon acoustic oscillations,
there is no need for velocity segregation
(=1.050.05). This result agrees with
expectations for velocity segregation from state-of-the-art numerical
simulations of clusters. Together with the improved agreement between the new
WMAP results and recent cosmic shear measurements, this result demonstrates
that the amplitude of large-scale structure in the nearby universe matches that
predicted from the structure seen in the microwave background. The new
constraint we place on velocity segregation in clusters indicates that virial
mass estimates for clusters are reasonably accurate. This result suggests that
future cluster surveys will be able to probe both cosmological parameters and
fundamental cluster physics.Comment: 4 pages, 2 color figures, submitted to ApJ Letter
CLASH: Precise New Constraints on the Mass Profile of Abell 2261
We precisely constrain the inner mass profile of Abell 2261 (z=0.225) for the
first time and determine this cluster is not "over-concentrated" as found
previously, implying a formation time in agreement with {\Lambda}CDM
expectations. These results are based on strong lensing analyses of new 16-band
HST imaging obtained as part of the Cluster Lensing and Supernova survey with
Hubble (CLASH). Combining this with revised weak lensing analyses of Subaru
wide field imaging with 5-band Subaru + KPNO photometry, we place tight new
constraints on the halo virial mass M_vir = 2.2\pm0.2\times10^15 M\odot/h70
(within r \approx 3 Mpc/h70) and concentration c = 6.2 \pm 0.3 when assuming a
spherical halo. This agrees broadly with average c(M,z) predictions from recent
{\Lambda}CDM simulations which span 5 <~ 8. Our most significant
systematic uncertainty is halo elongation along the line of sight. To estimate
this, we also derive a mass profile based on archival Chandra X-ray
observations and find it to be ~35% lower than our lensing-derived profile at
r2500 ~ 600 kpc. Agreement can be achieved by a halo elongated with a ~2:1 axis
ratio along our line of sight. For this elongated halo model, we find M_vir =
1.7\pm0.2\times10^15 M\odot/h70 and c_vir = 4.6\pm0.2, placing rough lower
limits on these values. The need for halo elongation can be partially obviated
by non-thermal pressure support and, perhaps entirely, by systematic errors in
the X-ray mass measurements. We estimate the effect of background structures
based on MMT/Hectospec spectroscopic redshifts and find these tend to lower
Mvir further by ~7% and increase cvir by ~5%.Comment: Submitted to the Astrophysical Journal. 19 pages, 14 figure
Effects of Neonatal Neural Progenitor Cell Implantation on Adult Neuroanatomy and Cognition in the Ts65Dn Model of Down Syndrome
As much of the aberrant neural development in Down syndrome (DS) occurs postnatally, an early opportunity exists to intervene and influence life-long cognitive development. Recent success using neural progenitor cells (NPC) in models of adult neurodegeneration indicate such therapy may be a viable option in diseases such as DS. Murine NPC (mNPC, C17.2 cell line) or saline were implanted bilaterally into the dorsal hippocampus of postnatal day 2 (PND 2) Ts65Dn pups to explore the feasibility of early postnatal treatment in this mouse model of DS. Disomic littermates provided karyotype controls for trisomic pups. Pups were monitored for developmental milestone achievement, and then underwent adult behavior testing at 14 weeks of age. We found that implanted mNPC survived into adulthood and migrated beyond the implant site in both karyotypes. The implantation of mNPC resulted in a significant increase in the density of dentate granule cells. However, mNPC implantation did not elicit cognitive changes in trisomic mice either neonatally or in adulthood. To the best of our knowledge, these results constitute the first assessment of mNPC as an early intervention on cognitive ability in a DS model
Exome-wide association study to identify rare variants influencing COVID-19 outcomes : Results from the Host Genetics Initiative
Publisher Copyright: Copyright: © 2022 Butler-Laporte et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Host genetics is a key determinant of COVID-19 outcomes. Previously, the COVID-19 Host Genetics Initiative genome-wide association study used common variants to identify multiple loci associated with COVID-19 outcomes. However, variants with the largest impact on COVID-19 outcomes are expected to be rare in the population. Hence, studying rare variants may provide additional insights into disease susceptibility and pathogenesis, thereby informing therapeutics development. Here, we combined whole-exome and whole-genome sequencing from 21 cohorts across 12 countries and performed rare variant exome-wide burden analyses for COVID-19 outcomes. In an analysis of 5,085 severe disease cases and 571,737 controls, we observed that carrying a rare deleterious variant in the SARS-CoV-2 sensor toll-like receptor TLR7 (on chromosome X) was associated with a 5.3-fold increase in severe disease (95% CI: 2.75–10.05, p = 5.41x10-7). This association was consistent across sexes. These results further support TLR7 as a genetic determinant of severe disease and suggest that larger studies on rare variants influencing COVID-19 outcomes could provide additional insights.Peer reviewe
Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severity
The combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole-exome sequencing data of about 4000 SARS-CoV-2-positive individuals were used to define an interpretable machine-learning model for predicting COVID-19 severity. First, variants were converted into separate sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. The Boolean features selected by these logistic models were combined into an Integrated PolyGenic Score that offers a synthetic and interpretable index for describing the contribution of host genetics in COVID-19 severity, as demonstrated through testing in several independent cohorts. Selected features belong to ultra-rare, rare, low-frequency, and common variants, including those in linkage disequilibrium with known GWAS loci. Noteworthily, around one quarter of the selected genes are sex-specific. Pathway analysis of the selected genes associated with COVID-19 severity reflected the multi-organ nature of the disease. The proposed model might provide useful information for developing diagnostics and therapeutics, while also being able to guide bedside disease management. © 2021, The Author(s)
Exercise training improves aerobic endurance and musculoskeletal fitness in female cardiac transplant recipients
Aim:
Female cardiac transplant recipients' aerobic capacity is 60% lower than sex and age-predicted values. The effect of exercise training on restoring the impaired aerobic endurance and muscle strength in female cardiac transplant recipients is not known. This study examined the effect that aerobic and strength training have on improving aerobic endurance and muscle strength in female cardiac transplant recipients.
Methods:
20 female cardiac transplant recipients (51 ± 11 years) participated in this investigation. The subjects performed a baseline six-minute walk test and a leg-press strength test when they were discharged following cardiac transplantation. The subjects then participated in a 12-week exercise program consisting of aerobic and lower extremity strength training. Baseline assessments were repeated following completion of the exercise intervention.
Results:
At baseline, the cardiac transplant recipients' aerobic endurance was 50% lower than age-matched predicted values. The training program resulted in a significant increase in aerobic endurance (pre-training: 322 ± 104 m vs. post-training: 501 ± 99 m, p < 0.05) and leg-press strength (pre-training: 48 ± 16 kg. vs. post-training: 78 ± 27 kg, p < 0.05).
Conclusion:
Aerobic and strength training are effective interventions that can partially restore the impaired aerobic endurance and strength found in female cardiac transplant recipients.Kinesiology, School ofNon UBCEducation, Faculty ofReviewedFacult