2,753 research outputs found
Formation of Shore-Normal Grooves (Gutters) in Sandstone by Wave Action.
Regularly spaced incised shore-normal grooves (gutters) on plane consolidated surfaces in littoral and sublittoral zones are widely observed in the marine geological record. Despite their common occurrence there are few investigations into their origins in contemporary marine environments. While their formation is often attributed to wave-induced currents related to wave swash and backwash on the beach-face, no conceptual model has been advanced to explain the presence of gutters, their morphology or their quasi-regular alongshore spacing. The paper examines gutters cut in soft sandstone at Medmerry near Selsey, UK and argues that their formation is related to wave breaking and swash zone processes during an unprecedented sequence of storms in the winter of 2013/14. During this period exceptionally high near-shore waves (Hs around 6m) were recorded for the south coast beaches and these storm conditions persisted periodically through to mid-February 2014. The consequence was extensive beach erosion and the exposure of underlying substrates. In this study gutter morphology was quantified using terrestrial lidar and a wave-resolving numerical model was used to defined the nearshore wave conditions and swash characteristics. Three of the largest storm events during the winter of 2013/14 were modelled: (a) moderate waves coincident with an exceptionally high tide; (b) exceptionally high waves occurring during neap tides; and (c) high waves occurring during spring tides. The model results showed swash zone shear stress is a dome-shaped function of distance across the beach-face thereby controlling gutter depth. Further, high-speed sheet flows characterised by periodic, shore-normal, high and low speed streaks alongshore are thought to be implicated in the mechanism controlling gutter spacing. However, in any situation, the specific spacing of gutters is moderated by both the local sheet flow characteristics and the larger-scale morphological forcing. Together these factors indicate that gutter spacing is an emergent property which makes spacing unpredictable
Secondary forest succession differs through naturalised gorse and native kÄnuka near Wellington and Nelson
The dominant native woody species forming early successional vegetation on formerly forested sites
in lowland New Zealand were kÄnuka (Kunzea ericoides) and mÄnuka (Leptospermum scoparium) (Myrtaceae).
These have been replaced extensively by gorse (Ulex europaeus, Fabaceae), a naturalised species in New
Zealand. Because gorse typically gives way to native broadleaved (angiosperm) forest in about 30 years, it is
often considered desirable for facilitating native forest restoration. We tested three hypotheses, derived from the
New Zealand literature, on gorse and kÄnuka: (1) kÄnuka stands have a different species composition and greater
species richness than gorse stands at comparable successional stages; (2) differences between gorse and kÄnuka
stands do not lessen over time; and (3) several native plant taxa are absent from or less common in gorse than
in kÄnuka stands. We sampled 48 scrub or low-forest sites in two regions, Wellington and Nelson. Sites were
classified into one of four predefined categories ā young gorse, young kÄnuka, old gorse, old kÄnuka ā based
on canopy height of the succession and the dominant early-successional woody species. Few characteristics of
the sites and surrounding landscapes differed significantly among site categories, and none consistently across
regions. The vegetation composition of gorse and kÄnuka and their immediate successors differed in both
regions, mainly in native woody species. Species richness was often lower in gorse and there were fewer smallleaved
shrubs and orchids in gorse. Persistent differences at the older sites suggest the successional trajectories
will not converge in the immediate future; gorse leads to different forest from that developed through kÄnuka.
Gorse-dominated succession is therefore not a direct substitute for native successions. We suggest areas of early
native succession should be preserved, and initiated in landscapes where successions are dominated by gorse
or other naturalised shrubs.Research was funded
by the Department of Conservation under science
investigation number 3591
Deep Search For Molecular Oxygen in TW Hya
The dominant form of oxygen in cold molecular clouds is gas-phase carbon
monoxide (CO) and ice-phase water (HO). Yet, in planet-forming disks around
young stars, gas-phase CO and HO are less abundant relative to their ISM
values, and no other major oxygen-carrying molecules have been detected. Some
astrochemical models predict that gas-phase molecular oxygen (O) should be
a major carrier of volatile oxygen in disks. We report a deep search for
emission from the isotopologue OO ( line at 233.946
GHz) in the nearby protoplanetary disk around TW Hya. We used imaging
techniques and matched filtering to search for weak emission but do not detect
OO. Based on our results, we calculate upper limits on the
gas-phase O abundance in TW Hya of relative to H,
which is orders of magnitude below solar oxygen abundance. We conclude
that gas-phase O is not a major oxygen-carrier in TW Hya. Two other
potential oxygen-carrying molecules, SO and SO, were covered in our
observations, which we also do not detect. Additionally, we report a
serendipitous detection of the CN hyperfine
transitions, and , at 219.9 GHz, which we found via
matched filtering and confirm through imaging.Comment: 10 pages, 6 figures, Accepted for publication in Ap
Preāemptive and preventive opioids for postoperative pain in adults undergoing all types of surgery
Background: Postoperative pain is a common consequence of surgery and can have deleterious effects. It has been suggested that the administration of opioid analgesia before a painful stimulus may improve pain control. This can be done in two ways. We defined 'preventive opioids' as opioids administered before incision and continued postoperatively, and 'preāemptive opioids' as opioids given before incision but not continued postoperatively. Both preāemptive and preventive analgesia involve the initiation of an analgesic agent prior to surgical incision with the aim of reducing intraoperative nociception and therefore postoperative pain.Objectives: To assess the efficacy of preventive and preāemptive opioids for reducing postoperative pain in adults undergoing all types of surgery.Search methods: We searched the following electronic databases: CENTRAL, MEDLINE, Embase, AMED, and CINAHL (up to 18 March 2018). In addition, we searched for unpublished studies in three clinical trial databases, conference proceedings, grey literature databases, and reference lists of retrieved articles. We did not apply any restrictions on language or date of publication.Selection criteria: We included parallelāgroup randomized controlled trials (RCTs) only. We included participants aged over 15 years old undergoing any type of surgery. We defined postincision opioids as the same intervention administered after incision whether single dose (as comparator with preāemptive analgesia) or continued postoperatively (as comparator with preventive analgesia) (control group). We considered studies that did and did not use a doubleādummy placebo (e.g. intervention group received active drug before incision and placebo after incision; control group received placebo before incision and active drug after incision).Data collection and analysis: We used the standard methodological procedures expected by Cochrane. Our primary outcomes were: early acute postoperative pain (measured within six hours and reported on a 0ātoā10 scale) and respiratory depression. Our secondary outcomes included: late acute postoperative pain (24 to 48 hours and reported on a 0ātoā10 scale), 24āhour morphine consumption, and adverse events (intraoperative bradycardia and hypotension). We used GRADE to assess the quality of the evidence for each outcome.Main results: We included 20 RCTs, including one unpublished study with 1343 participants. Two studies were awaiting classification as the full text for these studies was not available. One study evaluated preāemptive opioids, and 19 studies evaluated preventive opioids. We considered only one study to be at low risk of bias for most domains. The surgeries and opioids used varied, although roughly half of the included studies were conducted in abdominal hysterectomy, and around a quarter used morphine as the intervention. All studies were conducted in secondary care.Preāemptive opioids compared to postincision opioidsFor preāemptive opioids in dental surgery, there may be a reduction in early acute postoperative pain (mean difference (MD) ā1.20, 95% confidence interval (CI) ā1.75 to ā0.65; 40 participants; 1 study; lowāquality evidence). This study did not report on adverse events (respiratory depression, bradycardia, or hypotension). There may be a reduction in late acute postoperative pain (MD ā2.10, 95% CI ā2.57 to ā1.63; 40 participants; 1 study; lowāquality evidence). This study did not report 24āhour morphine consumption.Preventive opioids compared to postincision opioidsFor preventive opioids, there was probably no reduction in early acute postoperative pain (MD 0.11, 95% CI ā0.32 to 0.53; 706 participants; 10 studies; I2 = 61%; moderateāquality evidence). There were no events of respiratory depression in four studies (433 participants). There was no important reduction in late acute postoperative pain (MD ā0.06, 95% CI ā0.13 to 0.01; 668 participants; 9 studies; I2 = 0%; moderateāquality evidence). There may be a small reduction in 24āhour morphine consumption (MD ā4.91 mg, 95% CI ā9.39 mg to ā0.44 mg; 526 participants; 11 studies; I2 = 82%; very lowāquality evidence). There may be similar rates of bradycardia (risk ratio (RR) 0.33, 95% CI 0.01 to 7.88; 112 participants; 2 studies; I2 = 0%; lowāquality evidence) and hypotension (RR 1.08, 95% CI 0.25 to 4.73; 88 participants; 2 studies; I2 = 0%; lowāquality evidence).Authors' conclusions: Due to the low quality of the evidence, we are uncertain whether preāemptive opioids reduce postoperative pain. Based on the trials conducted thus far, there was no clear evidence that preventive opioids result in reductions in pain scores. It was unclear if there was a reduction in morphine consumption due to very lowāquality of evidence. Too few studies reported adverse events to be able to draw any definitive conclusions. Once assessed, the two studies awaiting classification may alter the conclusions of the review
V5856 Sagittarii/2016: Broad Multi-Epoch Spectral Coverage of a Sustained High Luminosity Nova
Nova V5856 Sagittarii is unique for having remained more than nine magnitudes
above its pre-outburst brightness for more than six years. Extensive visible
and IR spectra from the time of outburst to the present epoch reveal separate
emitting regions with distinct spectral characteristics. Permitted emission
lines have both broad and narrow components, whereas the forbidden line
profiles are almost entirely broad. The permitted line components frequently
display P Cygni profiles indicating high optical depth, whereas the broad
components do not show detectable absorption. The densities and velocities
deduced from the spectra, including differences in the O I 7773 and 8446 lines,
are not consistent with an on-going wind. Instead, the prolonged high
luminosity and spectral characteristics are indicative of a post-outburst
common envelope that enshrouds the binary, and is likely the primary source of
the visible and IR emission.Comment: 27 pages; 13 figures. Accepted for publication in the Ap
An Investigation into Genetic Associations with Musculoskeletal Soft Tissue Injuries in Elite Rugby ā Preliminary Findings
Peer reviewe
Improving the mental health and mental health support available to adolescents in out-of-home care via Adolescent-Focused Low-Intensity Life Story Work: a realist review
Objectives: Life Story Work (LSW) is used to promote the mental health and well-being of children and adolescents living in out-of-home care. LSW should be offered to all but is conventionally delivered in high-intensity ways. Low-intensity approaches are more accessible but there is significant variation and little guidance for supporting adolescents. We aimed to create guidance for Adolescent-Focused Low-Intensity LSW.
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Design: Realist review.
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Data sources: MEDLINE, Embase, PsycINFO, Sociology Collection (ProQuest), CINAHL, CDAS, Web of Science (SCIE, SSCI), Social Care Online and grey literature sources. Searches were performed between December 2021 and March 2022.
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Eligibility criteria: Documents on children and adolescents in care, LSW and/or low-intensity interventions to improve mental health were included. Documents focusing on parenting style and contact with birth family were excluded.
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Analysis: Documents were analysed using a realist logic of analysis. In consultation with Content Expert Groups (comprising professionals and care leavers), we developed an initial programme theory. Data relating to and challenging the initial programme theory were extracted and context-mechanism-outcome-configurations developed, critiqued and refined in an iterative fashion. Interpretations were drawn from context-mechanism-outcome-configurations to enhance the programme theory.
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Results: 75 documents contributed to the analysis. Generally, studies were small-scale and lacked in-depth methods and evaluation descriptions. Findings indicated important factors contribute to the development of high-quality Adolescent-Focused Low-Intensity LSW. Adolescent-Focused Low-Intensity LSW should be person-centred, begin in the now, involve co-construction, record everyday positive life events and be supported by trained carer(s). Context-mechanism-outcome-configurations relating to these themes are reported.
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Conclusions: Using this knowledge we developed initial practice guidance to support social care to deliver better quality Adolescent-Focused Low-Intensity LSW more consistently. To address gaps in our knowledge about the impact of Adolescent-Focused Low-Intensity LSW, further primary research is needed to strengthen understandings of how this intervention works (or not) in different contexts.
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PROSPERO registration number: CRD42021279816
Bone Mineral Density and Associated Genetic Variants in High-level Caucasian Marathon Runners
INTRODUCTION:Endurance runners (except those who may have low energy availability) tend to have higher total and/or loading site-specific bone mineral density (BMD) in comparison with non-athletes, most likely due to the larger volume of exercise completed. A large genetic component also contributes to BMD, although little is known about which specific genes are involved, whether particular genotypes are sensitive to mechanical loading and the impact of such an interaction on BMD. This study investigated if high-level endurance runners possess enhanced BMD associated with an āadvantageousā genetic predisposition, via a potential gene-physical activity interaction.METHODS:Age- and weight-adjusted total BMD (TBMD) and leg BMD (LBMD) measured via Dual-energy X-ray absorptiometry of 67 high-level Caucasian marathon runners (males < 2 h 45 min, n = 37; females < 3 15 min, n = 30) was compared with 40 male and 26 female non-athletes. LRP5 rs3736228, TNFRSF11B rs4355801, VDR rs2228570, WNT16 rs3801387 and AXIN1 rs9921222 variants were then investigated singularly, and collectively, as a total genotype score (TGS) via multivariate analysis of variance in a subgroup of this cohort (male runners n = 19, controls n = 26; female runners n = 17, controls n = 14). RESULTS:Male runners had higher TBMD (1.34 vs 1.28 g/cm2; P=0.02) and LBMD (1.53 vs 1.42 g/cm2; P=<0.01) than non-athletes. Female runners had higher LBMD than non-athletes (1.30 vs 1.22 g/cm2; P=0.02) but not TBMD (1.23 vs 1.18 g/cm2; P=0.22). An interaction (P=0.047) was observed between VDR rs2228570 genotype and group regarding LBMD in males: ff genotype runners had 0.02 g/cm2 higher LBMD than FF or Ff runners, but the FF genotype had the highest LBMD (1.45 g/cm2) amongst non-athletes. LBMD was also 0.12 g/cm2 higher in ff runners compared to ff non-athletes, whereas FF and Ff runners had 0.09 g/cm2 higher LBMD compared to their genotype-matched controls. No other interactions or variants, individually or collectively as part of a TGS, were associated with BMD (Pā„0.11). CONCLUSION:High-level female runners possess higher LBMD but not TBMD in comparison with non-athletes whereas male runners possess both higher TBMD and LBMD than non-athletes. Consistent with prior literature, we observed higher BMD in VDR rs2228570 FF genotype in non-athletes, which may be due to increased biological activity associated with the F variant. However, our preliminary data suggest that the ff genotype may be associated with enhanced LBMD in male runners via a gene-environment interaction.Peer reviewedFinal Published versio
Gluon Propagator in the Infrared Region
The gluon propagator is calculated in quenched QCD for two different lattice
sizes (16^3x48 and 32^3x64) at beta=6.0. The volume dependence of the
propagator in Landau gauge is studied. The smaller lattice is instrumental in
revealing finite volume and anisotropic lattice artefacts. Methods for
minimising these artefacts are developed and applied to the larger lattice
data. New structure seen in the infrared region survives these conservative
cuts to the lattice data. This structure serves to rule out a number of models
that have appeared in the literature. A fit to a simple analytical form
capturing the momentum dependence of the nonperturbative gluon propagator is
also reported.Comment: 13 pages, 9 figures, using RevTeX. Submitted to Phys. Rev. D. This
and related papers can also be obtained from
http://www.physics.adelaide.edu.au/~jskuller/papers
Anthropometric and Physiological Characteristics of Elite Male Rugby Athletes
This is the first article to review the anthropometric and physiological characteristics required for elite rugby performance within both Rugby Union (RU) and Rugby League (RL). Anthropometric characteristics such as height and mass, and physiological characteristics such as speed and muscular strength, have previously been advocated as key discriminators of playing level within rugby. This review aimed to identify the key anthropometric and physiological properties required for elite performance in rugby, distinguishing between RU and RL, forwards and backs and competitive levels. There are differences between competitive standards such that, at the elite level, athletes are heaviest (RU forwards ~111 kg, backs ~93 kg; RL forwards ~103 kg, backs ~90 kg) with lowest % body fat (RU forwards ~15%, backs ~12%; RL forwards ~14%, backs ~11%), they have most fat-free mass and are strongest (Back squat: RU forwards ~176 kg, backs ~157 kg; RL forwards ~188 kg, backs ~ 168 kg; Bench press: RU forwards ~131 kg, backs ~118 kg; RL forwards ~122 kg, backs ~113 kg) and fastest (10 m: RU forwards ~1.87 s, backs ~1.77 s; 10 m RL forwards ~1.9 s, backs ~1.83 s). We also have unpublished data that indicate contemporary RU athletes have less body fat and are stronger and faster than the published data suggest. Regardless, well-developed speed, agility, lower-body power and strength characteristics
are vital for elite performance, probably reflect both environmental (training, diet, etc.) and genetic factors, distinguish between competitive levels and are therefore important determinants of elite status in rugby.Published versio
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