836 research outputs found
COMPARISON OF KINEMATICS AND ACCURACY OF OVERHAND AMERICAN FOOTBALL THROWING
This study examined elbow angle, wrist velocity and throwing accuracy during American Football throws. Six repetitions of three types of throws: Self-selected pass (SS), Lob pass (L), and a Bullet pass (B); were performed to hit a point scaled target from 10.97 m. Independent variables were frontal plane shoulder angle (more or less than 90º) and throw type; dependent variables were elbow angle in the sagittal plane, wrist velocity at ball release, and accuracy. There were no differences for shoulder angle for any variable; while throw types differed only for wrist speed (highest to lowest B, SS, and L). Significant interactions occurred for all variables. These findings suggest that recommendations for American football throwing technique are complicated by the combination of throw type and shoulder angle; and that with no restrictions subjects will throw with more accuracy
The role of HLA-DP mismatches and donor specific HLA-DP antibodies in kidney transplantation : a case series
BACKGROUND:
The impact of HLA-DP mismatches on renal allograft outcome is still poorly understood and is suggested to be less than that of the other HLA loci. The common association of HLA-DP donor-specific antibodies (DSA) with other DSA obviates the evaluation of the actual effect of HLA-DP DSA.
METHODS:
From a large multicenter data collection, we retrospectively evaluated the significance of HLA-DP DSA on transplant outcome and the immunogenicity of HLA-DP eplet mismatches with respect to the induction of HLA-DP DSA. Furthermore, we evaluated the association between the MFI of HLA-DP antibodies detected in Luminex assays and the outcome of flowcytometric/complement-dependent cytotoxicity (CDC) crossmatches.
RESULTS:
In patients with isolated pretransplant HLA-DP antibodies (N = 13), 6 experienced antibody-mediated rejection (AMR) and 3 patients lost their graft. In HLAMatchmaker analysis of HLA-DP mismatches (N = 72), HLA-DP DSA developed after cessation of immunosuppression in all cases with 84DEAV (N = 14), in 86% of cases with 85GPM (N = 6/7), in 50% of cases with 56E (N = 6/12) and in 40% of cases with 56A mismatch (N = 2/5). Correlation analysis between isolated HLA-DP DSA MFI and crossmatches (N = 90) showed negative crossmatch results with HLA-DP DSA MFI <2000 (N = 14). Below an MFI of 10,000 CDC crossmatches were also negative (N = 33). Above these MFI values both positive (N = 35) and negative (N = 16) crossmatch results were generated.
CONCLUSIONS:
Isolated HLA-DP DSA are rare, yet constitute a significant risk for AMR. We identified high-risk eplet mismatches that can lead to HLA-DP DSA formation. We therefore recommend HLA-DP typing to perform HLA-DP DSA analysis before transplantation. HLA-DP DSA with high MFI were not always correlated with positive crossmatch results
Was there a '4.2ka event' in Great Britain and Ireland? Evidence from the peatland record
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Palaeoenvironmental and archaeological data from several regions around the world show evidence of a multi-centennial climatic event occurring approximately 4200cal yr BP (4.2ka). Whilst the climatic change and/or impact of the 4.2ka event is clear in certain regions, such as western Asia, evidence for the event has yet to be fully evaluated in northwest Europe. This study presents high-resolution, multi-proxy palaeoclimate records from sites in Northern Ireland, ideally located for an objective examination of the nature of the event in Great Britain and Ireland within the broader context of mid-Holocene climate change c. 6.5-2.5ka. The peatlands of northwest Europe possess considerable potential for the examination of climatic change in the North Atlantic region, demonstrated by the range of palaeohydrological proxy data generated during this study (peat humification, plant macrofossil and testate amoebae analyses) supported by a high-resolution chronology (including comprehensive AMS 14 C and tephrochronology). The inter-site testate amoebae reconstructions appear coherent and were combined to produce a regional climatic record, in marked contrast to the plant macrofossil and peat humification records that appear climatically complacent. The testate amoebae reconstruction, however, provides no compelling evidence for a 4.2ka event signal and is consistent with previously reported studies from across northwest Europe, suggesting the origin and impact of this event is spatially complex. © 2013 Elsevier Ltd.This research was carried out while T.P.R. held a UK Natural Environment Research Council studentship (NE/G524328/1) at the University of Exeter.
Time and force required for attendants boarding wheelchair users onto aircraft
Ensuring equal opportunity to all transport modes, including air travel, allows disabled people the same freedom of travel available to the rest of the population. However, boarding of wheelchair users onto airplanes is physically demanding for attendant airline or airport personal whom assist and time consuming and costly for airlines. This paper presents a comparison between two methods of boarding wheelchair users, measuring the forces required and the duration taken. Participants were asked to act as attendants and to board weighted wheelchairs onto simulated aircraft vestibules using two different manoeuvre methods (“going forwards” and “going backwards”), with two different loadings (“light” and “heavy”) in two different access scenarios (“level access” and “sloped access”) between the jet-way/scissor-lift and the aircraft. The results reveal that the “going backwards” technique is a slightly faster manoeuvre method but no difference in the forces required exist between the two methods. The weight of the wheelchair affected the forces required to complete the boarding and exceeded health and safety guidelines for attendants. Reducing the height of the step between the aircraft and the jet-way or scissor-lift is recommended. Relevance to Industry: The research highlights the juxtaposition between the need to board wheelchair users and the excessive force required by the attendants propelling the wheelchair
Impacts of marine instability across the East Antarctic Ice Sheet on Southern Ocean dynamics
Recent observations and modelling studies have demonstrated the potential for rapid and substantial retreat of large sectors of the East Antarctic Ice Sheet (EAIS). This has major implications for ocean circulation and global sea level. Here we examine the effects of increasing meltwater from the Wilkes Basin, one of the major marine-based sectors of the EAIS, on Southern Ocean dynamics. Climate model simulations reveal that the meltwater flux rapidly stratifies surface waters, leading to a dramatic decrease in the rate of Antarctic Bottom Water (AABW) formation. The surface ocean cools but, critically, the Southern Ocean warms by more than 1 degrees C at depth. This warming is accompanied by a Southern Ocean-wide “domino effect”, whereby the warming signal propagates westward with depth. Our results suggest that melting of one sector of the EAIS could result in accelerated warming across other sectors, including the Weddell Sea sector of the West Antarctic Ice Sheet. Thus, localised melting of the EAIS could potentially destabilise the wider Antarctic Ice Sheet
Delayed maximum northern European summer temperatures during the Last Interglacial as a result of Greenland Ice Sheet melt
This is the author accepted manuscript. The final version is available from the Geological Society of America via the DOI in this record.Here we report a new quantitative mean July temperature reconstruction using non-biting midges (chironomids) from the Danish Last Interglacial (LIG) site Hollerup (spanning 127–116 ka). We find that peak mean July temperatures of 17.5 °C, similar to those of the present day (1961–1990 CE), were reached shortly before the onset of the regional Carpinus pollen zone. Through comparison to terrestrial and marine sequences we demonstrate that peak summer warmth took place some three millennia after the onset of LIG warming in Europe, a marked delay in line with records from the North Atlantic. Crucially, the warmest northern European summer temperatures appear to follow maximum Greenland Ice Sheet mass loss, implying that meltwater substantially reduced Atlantic Meridional Overturning Circulation and depressed European temperatures during the early part of the interglacial.Turney and Fogwill thank the Australian Research Council (grants FL100100195, FT120100004,
LP120200724). Thanks to Bjørn Buchardt for providing the C:N data, Angela Self for help with statistical analysis, David Campbell and Alan Bedford for laboratory work, and three reviewers for their
constructive comments
The 5.2 ka climate event: Evidence from stable isotope and multi-proxy palaeoecological peatland records in Ireland
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Evidence for a major climate event at 5.2 ka has been reported globally and is associated with considerable societal disruption, but is poorly characterised in northwest Europe. This event forms part of a broader period of re-organisation in the Earth's ocean-atmosphere circulation system between 6 and 5 ka. This study tests the nature and timing of the event in northwest Europe, a region highly sensitive to change in meridional overturning circulation and mid-latitude westerly airflow. Here we report three high-resolution Irish multi-proxy records obtained from ombrotrophic peatlands that have robust chronological frameworks. We identify the 5.2 ka event by a sustained decrease in δ 18 O cellulose at all three sites, with additional and parallel changes in δ 13 C cellulose and palaeoecological (testate amoebae, plant macrofossil and humification) data from two sites in northern Ireland. Data from Sluggan Moss demonstrate a particularly coherent shift towards wetter conditions. These data support the hypothesis that the event was caused by a prolonged period of positive North Atlantic Oscillation conditions, resulting in pervasive cyclonic weather patterns across northwest Europe, increasing precipitation over Ireland.This research was carried out while T.P.R. held UK Natural Environment Research Council studentship at the University of Exeter (NE/G524328/1) and T.J.D held a studentship at the University of Southampton tied to the NERC RAPID Programme (NER/T/S/2002/00460). Radiocarbon support was provided by the NERC 14C Steering Committee (Allocation No.: 1523.0910), the NERC RAPID Programme and the Irish Quaternary Association via the IQUA Bill Watts 14Chrono award
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Blind source separation aided characterization of the γ′ strengthening phase in an advanced nickel-based superalloy by spectroscopic 4D electron microscopy
The γ’ strengthening phase in an advanced nickel-based superalloy, ATI 718Plus, was characterized using a blind source separation applied to a four dimensional X-ray microanalysis dataset obtained by scanning transmission electron microscopy. Selected patterns in the X-ray spectra identified by independent component analysis were found to be spatially and chemically representative of the matrix (γ) and precipitate phases (γ’) present in the superalloy, enabling their size, shape and distribution to be determined. The three dimensional chemical reconstruction of the microstructure may provide insight into the role of the various alloying elements in the evolution of the microstructure at the nano-scale.The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant Agreement 312483 - ESTEEM2 (Integrated Infrastructure Initiative-I3), as well as from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC grant agreement 291522 - 3DIMAGE. D.R. acknowledges support from the Royal Society’s Newton International Fellowship scheme. RKL acknowledges a Junior Research Fellowship at Clare College. RK acknowledges financial support from Rolls-Royce, EPSRC and the BMWi under EP/H022309/1, EP/H500375/1 and grant number 20T0813. F.d.l.P. and C.D. acknowledge 26 funding from the ERC under grant no. 259619 PHOTO EM. Special thanks to Giorgio Divitini and Lech Staniewicz for preparation of the FIB needle specimen and to Stephen A Croxall for SEM/FIB imaging.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.actamat.2016.01.04
Early warnings and missed alarms for abrupt monsoon transitions
Journal ArticlePalaeo-records from China demonstrate that the East Asian Summer Monsoon (EASM) is dominated by abrupt and large magnitude monsoon shifts on millennial timescales, switching between periods of high and weak monsoon rains. It has been hypothesized that over these timescales, the EASM exhibits two stable states with bifurcation-Type tipping points between them. Here we test this hypothesis by looking for early warning signals of past bifurcations in speleothem δ18O records from Sanbao Cave and Hulu Cave, China, spanning the penultimate glacial cycle. We find that although there are increases in both autocorrelation and variance preceding some of the monsoon transitions during this period, it is only immediately prior to the abrupt monsoon shift at the penultimate deglaciation (Termination II) that statistically significant increases are detected. To supplement our data analysis, we produce and analyse multiple model simulations that we derive from these data. We find hysteresis behaviour in our model simulations with transitions directly forced by solar insolation. However, signals of critical slowing down, which occur on the approach to a bifurcation, are only detectable in the model simulations when the change in system stability is sufficiently slow to be detected by the sampling resolution of the data set. This raises the possibility that the early warning "alarms" were missed in the speleothem data over the period 224-150 kyr and it was only at the monsoon termination that the change in the system stability was sufficiently slow to detect early warning signals
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