Serpula vermicularis reefs on very sheltered circalittoral muddy sand

Non

Oil accumulation, production characteristics, and targets for additional recovery in major oil reservoirs of Texas

UT Librarie

Comparing the Influence of Different Overhand/Underhand Stacking Combinations of Reversing Half-Hitches on Alternating Posts on Arthroscopic Knot Security

Introduction Previous literature demonstrated the importanceof stacking at least three reversing half-hitches on alternating posts(RHAPs) following arthroscopic knot placement. However, RHAPsconstruction involves looping the suture in either an “overhand” or an“underhand” manner as it relates to the post, which may affect knotsecurity. This study investigated the presently unidentified influenceof different stacking combinations of three RHAPs and suture materialon arthroscopic knot security. Methods Four different RHAPs stacking combinations were tiedwith three different suture materials. Ten knots of each configurationwere tied using each suture material, resulting in 120 evaluated knots.A single load-to-failure test was performed. The mode of failure andmean ultimate clinical failure load were recorded. Results Different overhand/underhand stacking combinations ofthree RHAPs had a statistically significant effect on arthroscopicknot strength and security; however, all combinations surpassed theminimum ultimate clinical failure threshold. Knots constructed witheither Force Fiber® or braided fishing line had mean ultimate clinicalfailure loads of greater than 200 N and most commonly failed due tosuture material breakage (100%, 60 - 80% respectively). Conversely,FiberWire® demonstrated lower mean ultimate clinical failure loadsand had a higher incidence of elongated but intact failure (60 - 90%). Conclusion Different overhand/underhand stacking combinationsof three RHAPs yielded an arthroscopic knot capable of secure tissuefixation. A significant effect was observed for suture materials on theknot strength. This study increases our understanding of suitableRHAPs construction following arthroscopic knot placement that canlead to improving the ultimate clinical failure loads of constructedarthroscopic knots observed between orthopedic surgeons

Continuous-variable quantum teleportation of entanglement

Entangled coherent states can be used to determine the entanglement fidelity for a device that is designed to teleport coherent states. This entanglement fidelity is universal, in that the calculation is independent of the use of entangled coherent states and applies generally to the teleportation of entanglement using coherent states. The average fidelity is shown to be a poor indicator of the capability of teleporting entanglement; i.e., very high average fidelity for the quantum teleportation apparatus can still result in low entanglement fidelity for one mode of the two-mode entangled coherent state.Comment: 5 pages, 1 figure, published versio

Axion-like particles as ultra high energy cosmic rays?

If Ultra High Energy Cosmic Rays (UHECRs) with E>4 10^{19} eV originate from BL Lacertae at cosmological distances as suggested by recent studies, the absence of the GZK cutoff can not be reconciled with Standard-Model particle properties. Axions would escape the GZK cutoff, but even the coherent conversion and back-conversion between photons and axions in large-scale magnetic fields is not enough to produce the required flux. However, one may construct models of other novel (pseudo)scalar neutral particles with properties that would allow for sufficient rates of particle production in the source and shower production in the atmosphere to explain the observations. As an explicit example for such particles we consider SUSY models with light sgoldstinos.Comment: 5 pages, 2 postscript figures, ref. adde

The clustering of ultra-high energy cosmic rays and their sources

The sky distribution of cosmic rays with energies above the 'GZK cutoff' holds important clues to their origin. The AGASA data, although consistent with isotropy, shows evidence for small-angle clustering, and it has been argued that such clusters are aligned with BL Lacertae objects, implicating these as sources. It has also been suggested that clusters can arise if the cosmic rays come from the decays of very massive relic particles in the Galactic halo, due to the expected clumping of cold dark matter. We examine these claims and show that both are in fact not justified.Comment: 13 pages, 8 figures, version in press at Phys. Rev.

Magnetotransport in the Normal State of La1.85Sr0.15Cu(1-y)Zn(y)O4 Films

We have studied the magnetotransport properties in the normal state for a series of La1.85Sr0.15Cu(1-y)Zn(y)O4 films with values of y, between 0 and 0.12. A variable degree of compressive or tensile strain results from the lattice mismatch between the substrate and the film, and affects the transport properties differently from the influence of the zinc impurities. In particular, the orbital magnetoresistance (OMR) varies with y but is strain-independent. The relations for the resistivity and the Hall angle and the proportionality between the OMR and tan^2 theta are followed about 70 K. We have been able to separate the strain and impurity effects by rewriting the above relations, where each term is strain-independent and depends on y only. We also find that changes in the lattice constants give rise to closely the same fractional changes in other terms of the equation.The OMR is more strongly supressed by the addition of impurities than tan^2 theta. We conclude that the relaxation ratethat governs Hall effect is not the same as for the magnetoresistance. We also suggest a correspondence between the transport properties and the opening of the pseudogap at a temperature which changes when the La-sr ratio changes, but does not change with the addition of the zinc impurities