174 research outputs found
Effect of plyometric training on swimming block start performance in adolescents
This study aimed to identify the effect of plyometric training (PT), when added to habitual training (HT) regimes, on swim start performance. After the completion of a baseline competitive swim start, 22 adolescent swimmers were randomly assigned to either a PT (n = 11, age: 13.1 ± 1.4 yr, mass: 50.6 ± 12.3 kg, stature: 162.9 ± 11.9 cm) or an HT group (n = 11, age: 12.6 ± 1.9 yr, mass: 43.3 ± 11.6 kg, stature: 157.6 ± 11.9 cm). Over an 8-week preseason period, the HT group continued with their normal training program, whereas the PT group added 2 additional 1-hour plyometric-specific sessions, incorporating prescribed exercises relating to the swimming block start (SBS). After completion of the training intervention, post-training swim start performance was reassessed. For both baseline and post-trials, swim performance was recorded using videography (50Hz Canon MVX460) in the sagital plane of motion. Through the use of Silicon Coach Pro analysis package, data revealed significantly greater change between baseline and post-trials for PT when compared with the HT group for swim performance time to 5.5 m (−0.59 s vs. −0.21 s; p < 0.01) and velocity of take-off to contact (0.19 ms−1 vs. −0.07 ms−1; p < 0.01). Considering the practical importance of a successful swim start to overall performance outcome, the current study has found that inclusion of suitable and safely implemented PT to adolescent performers, in addition to HT routines, can have a positive impact on swim start performance
Redescription of Serpinema octorugatum (Baylis, 1933) (Nematoda:Camallanidae) from the Malayan box turtle Cuora amboinensis (Daudin)(Chelonia: Bataguridae)
We redescribe the camallanid nematode Serpinema octorugatum (Baylis, 1933) from the box turtle Cuora amboinensis
(Daudin) collected in Malaysia. In this redescription, we amend the original description by noting that
there are only four cephalic papillae and that there are five pairs of post-anal papillae, and propose that the name
of this species be corrected from S. octorugatus to S. octorugatum. Additionally, we removed the tissues overlying
the buccal capsule and have used SEM studies to show that the peribuccal shields extend laterally from the buccal
capsule, forming a surface possibly used in muscle attachment. Furthermore, we show that the supposedly noncuticularised
cylinder connecting the buccal capsule to the oesophagus in the Camallanidae is part of the buccal
capsule and is, therefore, likely to be cuticularised. We also examine morphological measurements of taxonomic
interest for correlations with total body length and find that many characters traditionally used for inter-and intraspecific comparisons are correlated with total body length in adult female worms. This suggests that comparisons
between samples of adult female worms that do not account for the potential effect of total body length may be
misleading. However, we show that some features of taxonomic interest are not correlated with total body length
Micronutrient and amino acid losses during renal replacement therapy for acute kidney injury
© 2019 International Society of Nephrology Introduction: Malnutrition is common in patients with acute kidney injury (AKI), particularly in those requiring renal replacement therapy (RRT). Use of RRT removes metabolic waste products and toxins, but it will inevitably also remove useful molecules such as micronutrients, which might aggravate malnutrition. The RRT modalities vary in mechanism of solute removal; for example, intermittent hemodialysis (IHD) uses diffusion, continuous veno-venous hemofiltration (CVVH) uses convection, and sustained low-efficiency diafiltration (SLEDf) uses a combination of these. Methods: We assessed micronutrient and amino acid losses in 3 different RRT modalities in patients with AKI (IHD, n = 27; SLEDf, n = 12; CVVH, n = 21) after correction for dialysis dose and plasma concentrations. Results: Total losses were affected by modality; generally CVVH >> SLEDf > IHD (e.g., amino acid loss was 18.69 ± 3.04, 8.21 ± 4.07, and 5.13 ± 3.1 g, respectively; P < 0.001). Loss of specific trace elements (e.g., copper and zinc) during RRT was marked, with considerable heterogeneity between RRT types (e.g., +849 and +2325 μg/l lost during SLEDf vs. IHD, respectively), whereas effluent losses of copper and zinc decreased during CVVH (effect size relative to IHD, −3167 and −1442 μg/l, respectively). B vitamins were undetectable in effluent, but experimental modeling estimated 40% to 60% loss within the first 15 minutes of RRT. Conclusion: Micronutrient and amino acid losses are marked during RRT in patients with AKI, with variation between RRT modalities and micronutrients
Effect Threshold for Selenium Toxicity in Juvenile Splittail, Pogonichthys macrolepidotus A
In fish, selenium can bioaccumulate and cause adverse impacts. One of the fish species potentially at risk from selenium in the San Francisco Bay (California, USA) is the splittail (Pogonichthys macrolepidotus). Previous studies have derived a whole body NOAEL and LOAEL of 9.0 and 12.9 mg/kg-dw, respectively, for selenium in juveniles. However, the NOAEL/LOAEL approach leaves some uncertainty regarding the threshold of toxicity. Therefore, the raw data from the original experiment was re-analyzed using a logistic regression to derive EC10 values of 0.9 mg/kg-dw in feed, 7.9 mg/kg-dw in muscle, 18.6 mg/kg-dw in liver for juvenile splittail. Selenium concentrations in the dietary items of wild splittail exceed the EC10 values derived here. Thus, deformities previously reported in wild splittail may have resulted from selenium exposures via the food chain
Quantifying the UK's carbon dioxide flux: An atmospheric inverse modelling approach using a regional measurement network
We present a method to derive atmosphericobservation-based estimates of carbon dioxide (CO 2 ) fluxes at the national scale, demonstrated using data from a network of surface tall-tower sites across the UK and Ireland over the period 2013-2014. The inversion is carried out using simulations from a Lagrangian chemical transport model and an innovative hierarchical Bayesian Markov chain Monte Carlo (MCMC) framework, which addresses some of the traditional problems faced by inverse modelling studies, such as subjectivity in the specification of model and prior uncertainties. Biospheric fluxes related to gross primary productivity and terrestrial ecosystem respiration are solved separately in the inversion and then combined a posteriori to determine net ecosystem exchange of CO 2 . Two different models, Data Assimilation Linked Ecosystem Carbon (DALEC) and Joint UK Land Environment Simulator (JULES), provide prior estimates for these fluxes. We carry out separate inversions to assess the impact of these different priors on the posterior flux estimates and evaluate the differences between the prior and posterior estimates in terms of missing model components. The Numerical Atmospheric dispersion Modelling Environment (NAME) is used to relate fluxes to the measurements taken across the regional network. Posterior CO2 estimates from the two inversions agree within estimated uncertainties, despite large differences in the prior fluxes from the different models. With our method, averaging results from 2013 and 2014, we find a total annual net biospheric flux for the UK of 8±79 TgCO 2 yr -1 (DALEC prior) and 64±85 TgCO 2 yr -1 (JULES prior), where negative values represent an uptake of CO 2 . These biospheric CO 2 estimates show that annual UK biospheric sources and sinks are roughly in balance. These annual mean estimates consistently indicate a greater net release of CO 2 than the prior estimates, which show much more pronounced uptake in summer months
How dark the sky: the JWST backgrounds
We describe the sources of stray light and thermal background that affect
JWST observations; report actual backgrounds as measured from commissioning and
early science observations; compare those background levels to pre-launch
predictions; estimate the impact of the backgrounds on science performance; and
explore how the backgrounds probe the achieved configuration of the deployed
observatory. We find the observatory is limited by the irreducible
astrophysical backgrounds, rather than scattered stray light and thermal
self-emission, for all wavelengths micron, thus meeting the
level 1 requirement. This result was not assured given the open architecture
and thermal challenges of JWST, and is the result of meticulous attention to
stray light and thermal issues in the design, construction, integration, and
test phases. From background considerations alone, JWST will require less
integration time in the near-infrared compared to a system that just met the
stray light requirements; as such, JWST will be even more powerful than
expected for deep imaging at 1--5 micron. In the mid-infrared, the measured
thermal backgrounds closely match pre-launch predictions. The background near
10 micron is slightly higher than predicted before launch, but the impact on
observations is mitigated by the excellent throughput of MIRI, such that
instrument sensitivity will be as good as expected pre-launch. These measured
background levels are fully compatible with JWST's science goals and the Cycle
1 science program currently underway.Comment: Submitted to the "JWST Overview" special issue of PAS
Precise Black Hole Masses From Megamaser Disks: Black Hole-Bulge Relations at Low Mass
The black hole (BH)-bulge correlations have greatly influenced the last
decade of effort to understand galaxy evolution. Current knowledge of these
correlations is limited predominantly to high BH masses (M_BH> 10^8 M_sun) that
can be measured using direct stellar, gas, and maser kinematics. These objects,
however, do not represent the demographics of more typical L< L* galaxies. This
study transcends prior limitations to probe BHs that are an order of magnitude
lower in mass, using BH mass measurements derived from the dynamics of H_2O
megamasers in circumnuclear disks. The masers trace the Keplerian rotation of
circumnuclear molecular disks starting at radii of a few tenths of a pc from
the central BH. Modeling of the rotation curves, presented by Kuo et al.
(2010), yields BH masses with exquisite precision. We present stellar velocity
dispersion measurements for a sample of nine megamaser disk galaxies based on
long-slit observations using the B&C spectrograph on the Dupont telescope and
the DIS spectrograph on the 3.5m telescope at Apache Point. We also perform
bulge-to-disk decomposition of a subset of five of these galaxies with SDSS
imaging. The maser galaxies as a group fall below the M_BH-sigma* relation
defined by elliptical galaxies. We show, now with very precise BH mass
measurements, that the low-scatter power-law relation between M_BH and sigma*
seen in elliptical galaxies is not universal. The elliptical galaxy M_BH-sigma*
relation cannot be used to derive the BH mass function at low mass or the
zeropoint for active BH masses. The processes (perhaps BH self-regulation or
minor merging) that operate at higher mass have not effectively established an
M_BH-sigma* relation in this low-mass regime.Comment: 21 pages, 14 figures, accepted for publication in the Astrophysical
Journa
A Physical Model for z~2 Dust Obscured Galaxies
We present a physical model for the origin of z~2 Dust-Obscured Galaxies
(DOGs), a class of high-redshift ULIRGs selected at 24 micron which are
particularly optically faint (24/R>1000). By combining N-body/SPH simulations
of high redshift galaxy evolution with 3D polychromatic dust radiative transfer
models, we find that luminous DOGs (with F24 > 0.3 mJy at z~2 are well-modeled
as extreme gas-rich mergers in massive (~5x10^12-10^13 Msun) halos, with
elevated star formation rates (~500-1000 Msun/yr) and/or significant AGN growth
(Mdot > 0.5 Msun/yr), whereas less luminous DOGs are more diverse in nature. At
final coalescence, merger-driven DOGs transition from being starburst dominated
to AGN dominated, evolving from a "bump" to a power-law shaped mid-IR (IRAC)
spectral energy distribution (SED). After the DOG phase, the galaxy settles
back to exhibiting a "bump" SED with bluer colors and lower star formation
rates. While canonically power-law galaxies are associated with being
AGN-dominated, we find that the power-law mid-IR SED can owe both to direct AGN
contribution, as well as to a heavily dust obscured stellar bump at times that
the galaxy is starburst dominated. Thus power-law galaxies can be either
starburst or AGN dominated. Less luminous DOGs can be well-represented either
by mergers, or by massive ($M_{\rm baryon} ~5x10^11 Msun) secularly evolving
gas-rich disc galaxies (with SFR > 50 Msun/yr). By utilising similar models as
those employed in the SMG formation study of Narayanan et al. (2010), we
investigate the connection between DOGs and SMGs. We find that the most heavily
star-forming merger driven DOGs can be selected as Submillimetre Galaxies
(SMGs), while both merger-driven and secularly evolving DOGs typically satisfy
the BzK selection criteria.Comment: Accepted by MNRAS; major changes include better description of
dependency on ISM specification and updated models allowing dust to evolve
with metallicity
Coupled Motions Direct Electrons along Human Microsomal P450 Chains
Directional electron transfer through biological redox chains can be achieved by coupling reaction chemistry to conformational changes in individual redox enzymes
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