25,776 research outputs found
Carbonate Formation in Non-Aqueous Environments by Solid-Gas Carbonation of Silicates
We have produced synthetic analogues of cosmic silicates using the Sol Gel
method, producing amorphous silicates of composition Mg(x)Ca(1-x)SiO3. Using
synchrotron X-ray powder diffraction on Beamline I11 at the Diamond Light
Source, together with a newly-commissioned gas cell, real-time powder
diffraction scans have been taken of a range of silicates exposed to CO2 under
non-ambient conditions. The SXPD is complemented by other techniques including
Raman and Infrared Spectroscopy and SEM imaging.Comment: 5 pages, 3 figures. Contribution to the Proceedings of the First
European Conference on Laboratory Astrophysics (ECLA
Non-linear Elastic Response in Solid Helium: critical velocity or strain
Torsional oscillator experiments show evidence of mass decoupling in solid
4He. This decoupling is amplitude dependent, suggesting a critical velocity for
supersolidity. We observe similar behavior in the elastic shear modulus. By
measuring the shear modulus over a wide frequency range, we can distinguish
between an amplitude dependence which depends on velocity and one which depends
on some other parameter like displacement. In contrast to the torsional
oscillator behavior, the modulus depends on the magnitude of stress, not
velocity. We interpret our results in terms of the motion of dislocations which
are weakly pinned by 3He impurities but which break away when large stresses
are applied
Towards the Distributed Burning Regime in Turbulent Premixed Flames
Three-dimensional numerical simulations of canonical statistically-steady
statistically-planar turbulent flames have been used in an attempt to produce
distributed burning in lean methane and hydrogen flames. Dilatation across the
flame means that extremely large Karlovitz numbers are required; even at the
extreme levels of turbulence studied (up to a Karlovitz number of 8767)
distributed burning was only achieved in the hydrogen case. In this case,
turbulence was found to broaden the reaction zone visually by around an order
of magnitude, and thermodiffusive effects (typically present for lean hydrogen
flames) were not observed. In the preheat zone, the species compositions differ
considerably from those of one-dimensional flames based a number of different
transport models (mixture-averaged, unity Lewis number, and a turbulent eddy
viscosity model). The behaviour is a characteristic of turbulence dominating
non-unity Lewis number species transport, and the distinct limit is again
attributed to dilatation and its effect on the turbulence. Peak local reaction
rates are found to be lower in the distributed case than in the lower Karlovitz
cases but higher than in the laminar flame, which is attributed to effects that
arise from the modified fuel-temperature distribution that results from
turbulent mixing dominating low Lewis number thermodiffusive effects. Finally,
approaches to achieve distributed burning at realisable conditions are
discussed; factors that increase the likelihood of realising distributed
burning are higher pressure, lower equivalence ratio, higher Lewis number, and
lower reactant temperature
Sphere-valued harmonic maps with surface energy and the K13 problem
We consider an energy functional motivated by the celebrated K13 problem in the Oseen-Frank theory of nematic liquid crystals. It is defined for sphere-valued functions and appears as the usual Dirichlet energy with an additional surface term.
It is known that this energy is unbounded from below and our aim has been to study the local minimizers. We show that even having a critical point in a suitable energy space imposes severe restrictions on the boundary conditions. Having suitable boundary conditions makes the energy functional bounded and in this case we study the partial regularity of the minimizers.Romanian National Authority for Scientific Research and Innovation, CNCSUEFISCDI,
project number PN-II-RU-TE-2014-4-065
Association between MAPT polymorphism but not APOE promoter and elite rugby athlete status
INTRODUCTION: Incidence and outcomes of concussions have been hypothesised to be genetically influenced. The APOE Promoter G219T (rs405509) polymorphism has been associated with differential promoter activity and unfavourable outcomes after traumatic brain injury. The TT genotype is associated with a 3-fold greater risk of multiple concussions. The TT genotype of MAPT (rs10445337) has also been associated with poorer outcomes after concussion. Rugby has one of the highest incidences of concussion in sport, so it was hypothesised that APOE Promoter TT and MAPT TT genotypes would be less prevalent in elite rugby athletes because those genotypes, previously associated with increased risk, would be less compatible with achieving elite athlete status. METHODS: Participants were from the RugbyGene project, comprising elite Caucasian male rugby athletes (n = 528; mean (standard deviation) height 1.85 (0.07) m, mass 101 (14) kg, age 29 (7) yr), including 420 rugby union (RU) athletes that for some analyses were divided into forwards and backs and 108 rugby league (RL) athletes. Non-athletes were 592 Caucasian men and women (57% male, height 1.72 (0.10) m, mass 74 (14) kg, age 31 (7) yr). PCR of genomic DNA was used to determine genotypes using TaqMan probes, then groups were compared using χ2 and odds ratio (OR) statistics. RESULTS: All genotype data were in Hardy-Weinberg equilibrium. For MAPT (rs10445337), the risk genotype (TT) was underrepresented in rugby athletes (60%) compared to non-athletes (66%), CT more common in rugby athletes (34%) than non-athletes (29%) and little difference in CC genotype frequencies (χ2 = 7.092, P = 0.029; TT genotype frequency OR = 0.80, 95% confidence intervals (CI) = 0.62-1.02). There were no differences in MAPT (rs10445337) genotype frequencies between RU forwards and backs. For APOE Promoter G219T (rs405509), there were no differences in genotype frequencies between all athletes (RU and RL) and non-athletes (27% TT genotype in players and non-athletes), nor between RU forwards and backs. CONCLUSION: The MAPT (rs10445337) TT genotype is 6% less common in elite rugby athletes than non-athletes. Therefore, carrying at least one rs10445337 C allele appears to increase the probability of sustained career success in the high-risk concussion environment of elite rugby, perhaps via a greater ability to recover from concussions.Peer reviewe
Association of MMP3 but not TIMP2 gene variants with elite rugby player status and rugby code
Introduction: Achilles tendon pathology and anterior cruciate ligament rupture are multifactorial conditions for which genetic risk factors have been identified. Single nucleotide polymorphisms (SNPs) within the MMP3 (rs591058, rs679620, rs650108) and TIMP2 (rs4789932) genes have previously been associated with tendon and ligament pathologies. Although not entirely clear, prior literature indicates the risk alleles for Achilles tendon pathology as T (rs591058), G (rs679620) and A (rs650108) for MMP3. However, prior evidence regarding TIMP2 is equivocal. MMP3 is considered an essential regulator of matrix degradation and remodelling within diseased and normal musculoskeletal soft tissues. TIMP2 maintains homeostasis in the extracellular matrix in part by inhibiting MMP function. Given the high incidence and severity of tendon and ligament injuries in elite rugby athletes, we hypothesised that the aforementioned SNPs would be associated with career success. Methods: Participants from the RugbyGene project were elite Caucasian male rugby athletes (n = 566; mean (standard deviation) height 1.85 (0.07) m, mass 101 (14) kg, age 29 (7) yr), including 420 rugby union (RU) athletes that for some analyses were divided into forwards and backs and 120 rugby league (RL) athletes. Non-athletes were 589 Caucasian men and women (n = 589, 57% male, height 1.72 (0.10) m, mass 74 (14) kg, age 31 (7) yr). PCR of genomic DNA was used to determine genotypes using TaqMan probes, then groups were compared using Χ2 and odds ratio (OR) statistics. Results: As hypothesized, the MMP3 rs591058 risk genotype (TT) was less frequent in rugby athletes (28%) compared to non-athletes (33%) (Χ2 = 7.265, P = 0.026; OR = 1.18, 95% confidence intervals (CI) = 0.86-1.63). No differences were found for MMP3 rs679620, rs650108 or TIMP2 rs4789932 between rugby athletes and non-athletes. When RL athletes were compared to non-athletes, the risk genotype (TT) of MMP3 rs591058 was underrepresented in RL athletes (19%) compared to non-athletes (33%). The MMP3 rs679620 ‘protective’ allele (C) was more frequent in RL athletes (55%) compared to non-athletes (48%) (OR = 1.3, 95% CI = 0.98-1.74). However, for MMP3 rs650108 the ‘risk’ allele (A) was overrepresented in RL athletes (32%) compared to non-athletes (26%). There were no genotype differences for any gene variant between RU athletes and non-athletes. The ‘risk’ allele (T) of the MMP3 rs679629 polymorphism and the ‘protective’ allele (G) of the MMP3 rs650108 polymorphism were less common in RL (45%, 68%, respectively) than RU athletes (54%, 76%, respectively). Conclusion: We provide evidence for elite rugby athletes possessing a protective genetic profile regarding tendon and ligament injury risk. Notably, a less frequent rs591058 TT genotype in athletes suggests a lower risk of injury could therefore enhance career success in rugby. Furthermore, RL players appear to have differing genetic characteristics compared to their RU counterparts, which might reflect some differences in physiological demands between codes.Peer reviewedFinal Published versio
One hundred ten consecutive primary orthotopic liver transplants under FK 506 in adults.
An account is given of the 6- to 12-month survival, and causes of failure in 110 consecutive patients who underwent primary liver transplantation under treatment from the outset with FK 506 and steroids. The patient survival is 92.7%, and the first graft survival is 87.3%. At a very high frequency, the patients achieved good graft function, and they had a relatively low morbidity that was partially ascribable to minimal use and early discontinuance (in 60% of cases) of steroids. Renal dysfunction and other adverse findings were largely confined to patients with poor initial graft function and consequent apparent alteration of the kinetics of FK 506 elimination, causing functional overdosage. Results compare very favorably with our past record using conventional immunosuppression, and support the belief that FK 506 is a superior immunosuppressive agent which is suitable for chronic administration
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