454 research outputs found
THE BALL ORIENTATIONS USED BY PLACE KICKERS AT THE 2019 RUGBY WORLD CUP AND THEIR ASSOCIATIONS WITH KICK SUCCESS
The outcomes of place kicks can have a large impact on Rugby Union match results. This study investigated the ball orientations used in place kicking and their potential implications for success. All 416 place kicks from the 2019 Rugby World Cup were grouped into one of three ball orientation categories, and predicted odds of success were calculated for each category using a binomial logistic regression which accounted for situational factors known to affect performance outcome. Kicks taken using a slanted orientation (n = 152) had the greatest odds of success (90.0%) when taken from the mean tournament distance (29.7 m), compared to a near vertical (n = 116) orientation (84.4%), and near horizontal (n = 148) orientation (86.8%). A further investigation into the impact characteristics associated with each ball orientation is required to better understand the relative merits of each
Structure formation by cosmic strings with a cosmological constant
Final published version.Comment: 4 Page
Clustering of Primordial Black Holes. II. Evolution of Bound Systems
Primordial Black Holes (PBHs) that form from the collapse of density
perturbations are more clustered than the underlying density field. In a
previous paper, we showed the constraints that this has on the prospects of PBH
dark matter. In this paper we examine another consequence of this clustering:
the formation of bound systems of PBHs in the early universe. These would
hypothetically be the earliest gravitationally collapsed structures, forming
when the universe is still radiation dominated. Depending upon the size and
occupation of the clusters, PBH merging occurs before they would have otherwise
evaporated due to Hawking evaporation.Comment: 23 pages, 1 figure. Submitted to PR
A Comprehensive Archival Search for Counterparts to Ultra-Compact High Velocity Clouds: Five Local Volume Dwarf Galaxies
We report five Local Volume dwarf galaxies (two of which are presented here
for the first time) uncovered during a comprehensive archival search for
optical counterparts to ultra-compact high velocity clouds (UCHVCs). The UCHVC
population of HI clouds are thought to be candidate gas-rich, low mass halos at
the edge of the Local Group and beyond, but no comprehensive search for stellar
counterparts to these systems has been presented. Careful visual inspection of
all publicly available optical and ultraviolet imaging at the position of the
UCHVCs revealed six blue, diffuse counterparts with a morphology consistent
with a faint dwarf galaxy beyond the Local Group. Optical spectroscopy of all
six candidate dwarf counterparts show that five have an H-derived
velocity consistent with the coincident HI cloud, confirming their association,
the sixth diffuse counterpart is likely a background object. The size and
luminosity of the UCHVC dwarfs is consistent with other known Local Volume
dwarf irregular galaxies. The gas fraction () of the five
dwarfs are generally consistent with that of dwarf irregular galaxies in the
Local Volume, although ALFALFA-Dw1 (associated with ALFALFA UCHVC
HVC274.68+74.70123) has a very high 40. Despite the
heterogenous nature of our search, we demonstrate that the current dwarf
companions to UCHVCs are at the edge of detectability due to their low surface
brightness, and that deeper searches are likely to find more stellar systems.
If more sensitive searches do not reveal further stellar counterparts to
UCHVCs, then the dearth of such systems around the Local Group may be in
conflict with CDM simulations.Comment: 18 pages, 4 tables, 4 figures, ApJ Accepte
Building Strong for Tomorrow: Recommendations for the Organizational Design of the NOAA Climate Service
The U.S. Congress asked an expert panel of the National Academy of Public Administration to assist NOAA with a study and analysis of organizational options for a Climate Service within NOAA. Further, NOAA formally asked the Panel to provide an independent assessment of how NOAA should organize its climate capabilities and make recommendations for a Climate Service line office structure that would integrate NOAA's climate science and research with service delivery.Main FindingsThe Panel strongly supports the creation of a Climate Service to be established as a line office within NOAA.The Panel concluded that a NOAA Climate Service, properly configured and implemented, would be uniquely qualified to serve the public and private sectors as a lead federal agency for climate research and services, and to provide an ongoing accessible, authoritative clearinghouse for all federal science and services related to climate.The report also includes the Panel's observations and recommendations regarding the larger federal climate enterprise, key elements of support needed by the NOAA Climate Service and the importance to the new organization of a clear strategic plan and a comprehensive implementation plan. Additionally, the Panel offered observations about institutional change management in the federal sector, identified several management recommendations for implementation and addressed operational priorities and budget challenges
The angular correlations of galaxies in the COSMOS field
We present measurements of the two-point galaxy angular correlation function
w(\theta) in the COSMOS field. Independent determinations of w(\theta) as a
function of magnitude limit are presented for both the HST ACS catalog and also
for the ground-based data from Subaru and the CFHT. Despite having
significantly different masks, these three determinations agree well. At bright
magnitudes (IAB<22), our data generally match very well with existing
measurements and with mock catalogs based on semi-analytic galaxy formation
calculations of Kitzbichler and White from the Millennium Simulation. The
exception is that our result is at the upper end of the expected cosmic
variance scatter for \theta > 10 arcmin, which we attribute to a particularly
rich structure known to exist at z~0.8. For fainter samples, however, the level
of clustering is somewhat higher than reported by some previous studies: in all
three catalogues we find w(\theta=1')~0.014 at a median IAB magnitude of 24. At
these very faintest magnitudes, our measurements agree well with the latest
determinations from the Canada-France Legacy Survey. This level of clustering
is approximately double what is predicted by the semi-analytic catalogs (at all
angles). The semi-analytic results allow an estimate of cosmic variance, which
is too small to account for the discrepancy. We therefore conclude that the
mean amplitude of clustering at this level is higher than previously estimated.Comment: Six pages, five figures. Accepted for publication in the ApJS COSMOS
special issue, Sept. 200
The case against scaling defect models of cosmic structure formation
We calculate predictions from defect models of structure formation for both
the matter and Cosmic Microwave Background (CMB) over all observable scales.
Our results point to a serious problem reconciling the observed large-scale
galaxy distribution with the COBE normalization, a result which is robust for a
wide range of defect parameters. We conclude that standard scaling defect
models are in conflict with the data, and show how attempts to resolve the
problem by considering non-scaling defects would require radical departures
from the standard scaling picture.Comment: 7 Pages, Latex, 4 figure
Optical and Radio Properties of Extragalactic Sources Observed by the FIRST and SDSS Surveys
We discuss the optical and radio properties of 30,000 FIRST sources
positionally associated with an SDSS source in 1230 deg of sky. The
majority (83%) of the FIRST sources identified with an SDSS source brighter
than r=21 are optically resolved. We estimate an upper limit of 5% for the
fraction of quasars with broad-band optical colors indistinguishable from those
of stars. The distribution of quasars in the radio flux -- optical flux plane
supports the existence of the "quasar radio-dichotomy"; 8% of all quasars with
i<18.5 are radio-loud and this fraction seems independent of redshift and
optical luminosity. The radio-loud quasars have a redder median color by 0.08
mag, and a 3 times larger fraction of objects with red colors. FIRST galaxies
represent 5% of all SDSS galaxies with r<17.5, and 1% for r<20, and are
dominated by red galaxies. Magnitude and redshift limited samples show that
radio galaxies have a different optical luminosity distribution than non-radio
galaxies selected by the same criteria; when galaxies are further separated by
their colors, this result remains valid for both blue and red galaxies. The
distributions of radio-to-optical flux ratio are similar for blue and red
galaxies in redshift-limited samples; this similarity implies that the
difference in their luminosity functions, and resulting selection effects, are
the dominant cause for the preponderance of red radio galaxies in flux-limited
samples. We confirm that the AGN-to-starburst galaxy number ratio increases
with radio flux, and find that radio emission from AGNs is more concentrated
than radio emission from starburst galaxies (abridged).Comment: submitted to AJ, color gif figures, PS figures available from
[email protected]
Stereotactic radiotherapy for neovascular age-related macular degeneration (STAR): a pivotal, randomised, double-masked, sham-controlled device trial
Background: Neovascular age-related macular degeneration (nAMD) is a leading cause of blindness. The first-line therapy is anti-vascular endothelial growth factor (anti-VEGF) agents delivered by intravitreal injection. Ionising radiation mitigates key pathogenic processes underlying nAMD, and therefore has therapeutic potential. STAR aimed to assess whether stereotactic radiotherapy (SRT) reduces the number of anti-VEGF injections required, without sacrificing visual acuity. Methods: This pivotal, randomised, double-masked, sham-controlled trial enrolled participants with pretreated chronic active nAMD from 30 UK hospitals. Participants were randomly allocated in a 2:1 ratio to 16-Gray (Gy) SRT delivered using a robotically controlled device or sham SRT, stratified by treatment centre. Eligible participants were aged 50 years or older and had chronic active nAMD, with at least three previous anti-VEGF injections, including at least one in the last 4 months. Participants and all trial and image reading centre staff were masked to treatment allocation, except one unmasked statistician. The primary outcome was the number of intravitreal ranibizumab injections required over 2 years, tested for superiority (fewer injections). The main secondary outcome was Early Treatment Diabetic Retinopathy Study visual acuity at two years, tested for non-inferiority (five-letter margin). The primary analysis used the intention-to-treat principle, and safety was analysed per-protocol on participants with available data. The study is registered with ClinicalTrials.gov (NCT02243878) and is closed for recruitment. Findings: 411 participants enrolled between Jan 1, 2015, and Dec 27, 2019, and 274 were randomly allocated to the 16-Gy SRT group and 137 to the sham SRT group. 240 (58%) of all participants were female, and 171 (42%) of all participants were male. 241 participants in the 16-Gy SRT group and 118 participants in the sham group were included in the final analysis, and 409 patients were treated and formed the safety population, of whom two patients allocated to sham treatment erroneously received 16-Gy SRT. The SRT group received a mean of 10·7 injections (SD 6·3) over 2 years versus 13·3 injections (5·8) with sham, a reduction of 2·9 injections after adjusting for treatment centre (95% CI –4·2 to –1·6, p<0·0001). The SRT group best-corrected visual acuity change was non-inferior to sham (adjusted mean letter loss difference between groups, –1·7 letters [95% CI –4·2 to 0·8]). Adverse event rates were similar across groups, but reading centre-detected microvascular abnormalities occurred in 77 SRT-treated eyes (35%) and 13 (12%) sham-treated eyes. Overall, eyes with microvascular abnormalities tended to have better best-corrected visual acuity than those without. Fewer ranibizumab injections offset the cost of SRT, saving a mean of £565 per participant (95% CI –332 to 1483). Interpretation: SRT can reduce ranibizumab treatment burden without compromising vision. Funding: Medical Research Council and National Institute for Health and Care Research Efficacy and Mechanism Evaluation Programme.</p
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