305 research outputs found
ASSOCIATIONS BETWEEN CLINICAL AND PERFORMANCE TESTS IN SOCCER ATHLETES
The purpose of this study was to determine the relationship between selected Functional Movement Screen (FMS™) scores, quadriceps and hamstrings strength, and vertical jump performance to see if there is consistency between clinical and performance testing. Records for twelve NCAA-I female soccer players were selected for this study. The isolated scores from the hurdle step and deep squat portions of the FMS™ test were extracted, left and right peak knee extension and flexion torques from isokinetic tests at 60, 180, and 300 °/sec, and vertical jump heights were recorded. Bivariate correlations and a multiple regression analysis were conducted to explore relationships among variables. The results from this study indicated that the FMS™ test was a poor predictor of vertical jump height, but peak extension and flexion torques were related to the vertical jump in a complex relationship
Robust Chauvenet Outlier Rejection
Sigma clipping is commonly used in astronomy for outlier rejection, but the
number of standard deviations beyond which one should clip data from a sample
ultimately depends on the size of the sample. Chauvenet rejection is one of the
oldest, and simplest, ways to account for this, but, like sigma clipping,
depends on the sample's mean and standard deviation, neither of which are
robust quantities: Both are easily contaminated by the very outliers they are
being used to reject. Many, more robust measures of central tendency, and of
sample deviation, exist, but each has a tradeoff with precision. Here, we
demonstrate that outlier rejection can be both very robust and very precise if
decreasingly robust but increasingly precise techniques are applied in
sequence. To this end, we present a variation on Chauvenet rejection that we
call "robust" Chauvenet rejection (RCR), which uses three decreasingly
robust/increasingly precise measures of central tendency, and four decreasingly
robust/increasingly precise measures of sample deviation. We show this
sequential approach to be very effective for a wide variety of contaminant
types, even when a significant -- even dominant -- fraction of the sample is
contaminated, and especially when the contaminants are strong. Furthermore, we
have developed a bulk-rejection variant, to significantly decrease computing
times, and RCR can be applied both to weighted data, and when fitting
parameterized models to data. We present aperture photometry in a contaminated,
crowded field as an example. RCR may be used by anyone at
https://skynet.unc.edu/rcr, and source code is available there as well.Comment: 62 pages, 48 figures, 7 tables, accepted for publication in ApJ
Theology, Mission and Child: Global Perspectives
In our view there are three primary and equally constituent parts to the volume we have been commissioned to edit and collate, and these are therefore indicated in the title.https://scholar.csl.edu/edinburghcentenary/1023/thumbnail.jp
The critical velocity effect as a cause for the H\alpha emission from the Magellanic stream
Observations show significant H\alpha-emissions in the Galactic halo near the
edges of cold gas clouds of the Magellanic Stream. The source for the
ionization of the cold gas is still a widely open question. In our paper we
discuss the critical velocity effect as a possible explanation for the observed
H\alpha-emission. The critical velocity effect can yield a fast ionization of
cold gas if this neutral gas passes through a magnetized plasma under suitable
conditions. We show that for parameters that are typical for the Magellanic
Stream the critical velocity effect has to be considered as a possible
ionization source of high relevance.Comment: 9 pages, 2 figures. accepted, to appear in The Astrophysical Journa
Head-Tail Clouds: Drops to Probe the Diffuse Galactic Halo
A head-tail high-velocity cloud (HVC) is a neutral hydrogen halo cloud that
appears to be interacting with the diffuse halo medium as evident by its
compressed head trailed by a relatively diffuse tail. This paper presents a
sample of 116 head-tail HVCs across the southern sky (d < 2 deg) from the HI
Parkes All Sky Survey (HIPASS) HVC catalog, which has a spatial resolution of
15.5 arcmin (45 pc at 10 kpc) and a sensitivity of N_HI=2 x 10^(18) cm^(-2) (5
sigma). 35% of the HIPASS compact and semi-compact HVCs (CHVCs and :HVCs) can
be classified as head-tail clouds from their morphology. The clouds have
typical masses of 730 M_sun at 10 kpc (26,000 M_sun at 60 kpc) and the majority
can be associated with larger HVC complexes given their spatial and kinematic
proximity. This proximity, together with their similar properties to CHVCs and
:HVCs without head-tail structure, indicate the head-tail clouds have short
lifetimes, consistent with simulation predictions. Approximately half of the
head-tail clouds can be associated with the Magellanic System, with the
majority in the region of the Leading Arm with position angles pointing in the
general direction of the movement of the Magellanic System. The abundance in
the Leading Arm region is consistent with this feature being closer to the
Galactic disk than the Magellanic Stream and moving through a denser halo
medium. The head-tail clouds will feed the multi-phase halo medium rather than
the Galactic disk directly and provide additional evidence for a diffuse
Galactic halo medium extending to at least the distance of the Magellanic
Clouds.Comment: MNRAS Accepted, 10 figures, 7 in colo
Discrepancy between modelled and measured radial electric fields in the scrape-off layer of divertor tokamaks: a challenge for 2D fluid codes?
Exploring the Origin and Fate of the Magellanic Stream with Ultraviolet and Optical Absorption
(Abridged) We present an analysis of ionization and metal enrichment in the
Magellanic Stream (MS), the nearest gaseous tidal stream, using HST/STIS and
FUSE ultraviolet spectroscopy of two background AGN, NGC 7469 and Mrk 335. For
NGC 7469, we include optical spectroscopy from VLT/UVES. In both sightlines the
MS is detected in low-ion and high-ion absorption. Toward NGC 7469, we measure
a MS oxygen abundance [O/H]_MS=[OI/HI]=-1.00+/-0.05(stat)+/-0.08(syst),
supporting the view that the Stream originates in the SMC rather than the LMC.
We use CLOUDY to model the low-ion phase of the Stream as a photoionized plasma
using the observed Si III/Si II and C III/C II ratios. Toward Mrk 335 this
yields an ionization parameter log U between -3.45 and -3.15 and a gas density
log (n_H/cm^-3) between -2.51 and -2.21. Toward NGC 7469 we derive sub-solar
abundance ratios for [Si/O], [Fe/O], and [Al/O], indicating the presence of
dust in the MS. The high-ion column densities are too large to be explained by
photoionization, but also cannot be explained by a single-temperature
collisional-ionization model (equilibrium or non-equilibrium). This suggests
the high-ion plasma is multi-phase. Summing over the low-ion and high-ion
phases, we derive conservative lower limits on the ratio N(total H II)/N(H I)
of >19 toward NGC 7469 and >330 toward Mrk 335, showing that along these two
directions the vast majority of the Stream has been ionized. The presence of
warm-hot plasma together with the small-scale structure observed at 21 cm
provides evidence for an evaporative interaction with the hot Galactic corona.
This scenario, predicted by hydrodynamical simulations, suggests that the fate
of the MS will be to replenish the Galactic corona with new plasma, rather than
to bring neutral fuel to the disk.Comment: Accepted for publication in ApJ. 18 pages, 7 figures, all in colo
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