Some considerations on coastal processes relevant to sea level rise

The effects of potential sea level rise on the shoreline and shore environment have been briefly examined by considering the interactions between sea level rise and relevant coastal processes. These interactions have been reviewed beginning with a discussion of the need to reanalyze previous estimates of eustatic sea level rise and compaction effects in water level measurement. This is followed by considerations on sea level effects on coastal and estuarine tidal ranges, storm surge and water level response, and interaction with natural and constructed shoreline features. The desirability to reevaluate the well known Bruun Rule for estimating shoreline recession has been noted. The mechanics of ground and surface water intrusion with reference to sea level rise are then reviewed. This is followed by sedimentary processes in the estuaries including wetland response. Finally comments are included on some probable effects of sea level rise on coastal ecosystems. These interactions are complex and lead to shoreline evolution (under a sea level rise) which is highly site-specific. Models which determine shoreline change on the basis of inundation of terrestrial topography without considering relevant coastal processes are likely to lead to erroneous shoreline scenarios, particularly where the shoreline is composed of erodible sedimentary material. With some exceptions, present day knowledge of shoreline response to hydrodynamic forcing is inadequate for long-term quantitative predictions. A series of interrelated basic and applied research issues must be addressed in the coming decades to determine shoreline response to sea level change with an acceptable degree of confidence. (PDF contains 189 pages.

High order magnon bound states in the quasi-one-dimensional antiferromagnet α\alpha-NaMnO2_2

Here we report on the formation of two and three magnon bound states in the quasi-one-dimensional antiferromagnet $\alpha$-NaMnO$_2$, where the single-ion, uniaxial anisotropy inherent to the Mn$^{3+}$ ions in this material provides a binding mechanism capable of stabilizing higher order magnon bound states. While such states have long remained elusive in studies of antiferromagnetic chains, neutron scattering data presented here demonstrate that higher order $n>2$ composite magnons exist, and, specifically, that a weak three-magnon bound state is detected below the antiferromagnetic ordering transition of NaMnO$_2$. We corroborate our findings with exact numerical simulations of a one-dimensional Heisenberg chain with easy-axis anisotropy using matrix-product state techniques, finding a good quantitative agreement with the experiment. These results establish $\alpha$-NaMnO$_2$ as a unique platform for exploring the dynamics of composite magnon states inherent to a classical antiferromagnetic spin chain with Ising-like single ion anisotropy.Comment: 5 pages, 4 figure

Nonequilibrium brittle fracture propagation: Steady state, oscillations and intermittency

A minimal model is constructed for two-dimensional fracture propagation. The heterogeneous process zone is presumed to suppress stress relaxation rate, leading to non-quasistatic behavior. Using the Yoffe solution, I construct and solve a dynamical equation for the tip stress. I discuss a generic tip velocity response to local stress and find that noise-free propagation is either at steady state or oscillatory, depending only on one material parameter. Noise gives rise to intermittency and quasi-periodicity. The theory explains the velocity oscillations and the complicated behavior seen in polymeric and amorphous brittle materials. I suggest experimental verifications and new connections between velocity measurements and material properties.Comment: To appear in Phys. Rev. Lett., 6 pages, self-contained TeX file, 3 postscript figures upon request from author at [email protected] or [email protected], http://cnls-www.lanl.gov/homepages/rafi/rafindex.htm

Phytoplasmas associated with grapevine yellows in Virginia belong to group 16SrI, subgroup A (tomato big bud phytoplasma subgroup), and group 16SrIII, new subgroup I

Grapevine yellows disease in Virginia closely resembles flavescence doree and other grapevine yellows diseases, but the phytoplasmas infecting grapevines in Virginia are distinct from other grapevine yellows pathogens. RFLP analysis of PCR-amplified 16S rDNA indicated that a Virginia grapevine yellows phytoplasma, designated VGYIII was distinct from all other phytoplasmas studied, but was most closely related to spirea stunt (SP1), walnut witches' broom (WWB), and poinsettia branch-inducing (PoiB 1) phytoplasmas in subgroups E, G, and H, respectively, of 16S I RNA group 16SrIII. RFLP analysis also indicated the existence of sequence heterogeneity between the two rRNA operons in the genomes of SP 1 and WWB. Based on the results from RFLP and sequence comparisons with other group 16SrIII phytoplasmas, the VGYIII phytoplasma was classified in a new subgroup, designated 16SrIII-I. A second phytoplasma (VGYI) was detected in cultivated grapevines(Vitis vinifera L.) and in wild grapevines(V. riparia Michx.) and identified as a member of subgroup 16SrI-A. There was no evidence of flavescence doree, bois noir, or Australian grapevine yellows phytoplasmas in Virginia

Electromagnetic Meson Form Factors in the Salpeter Model

We present a covariant scheme to calculate mesonic transitions in the framework of the Salpeter equation for $q\bar{q}$-states. The full Bethe Salpeter amplitudes are reconstructed from equal time amplitudes which were obtained in a previous paper\cite{Mue} by solving the Salpeter equation for a confining plus an instanton induced interaction. This method is applied to calculate electromagnetic form factors and decay widths of low lying pseudoscalar and vector mesons including predictions for CEBAF experiments. We also describe the momentum transfer dependence for the processes $\pi^0,\eta,\eta'\rightarrow\gamma\gamma^*$.Comment: 22 pages including 10 figure

Effects of Symmetry Breaking on the Strong and Electroweak Interactions of the Vector Nonet

Starting from a chiral invariant and quark line rule conserving Lagrangian of pseudoscalar and vector nonets we introduce first and second order symmetry breaking as well as quark line rule violating terms and fit the parameters, at tree level, to many strong and electroweak processes. A number of predictions are made. The electroweak interactions are included in a manifestly gauge invariant manner. The resulting symmetry breaking pattern is discussed in detail. Specifically, for the ``strong'' interactions, we study all the vector meson masses and V -> \phi \phi decays, including isotopic spin violations. In the electroweak sector we study the { rho^0 , omega , phi } -> e^+e^- decays, { pi^+ , K^+ , K^0 } ``charge radii'', K_{l3} ``slope factor'' and the overall e^+e^- -> pi^+ pi^- process. It is hoped that the resulting model may be useful as a reasonable description of low energy physics in the range up to about 1 GeV.Comment: 43 pages (LaTeX), 5 PostScript figures are included as uuencoded-compressed-tar file at the en

Pion and Kaon Vector Form Factors

We develop a unitarity approach to consider the final state interaction corrections to the tree level graphs calculated from Chiral Perturbation Theory ($\chi PT$) allowing the inclusion of explicit resonance fields. The method is discussed considering the coupled channel pion and kaon vector form factors. These form factors are then matched with the one loop $\chi PT$ results. A very good description of experimental data is accomplished for the vector form factors and for the $\pi\pi$ P-wave phase shifts up to $\sqrt{s}\lesssim 1.2$ GeV, beyond which multiparticle states play a non negligible role. In particular the low and resonance energy regions are discussed in detail and for the former a comparison with one and two loop $\chi PT$ is made showing a remarkable coincidence with the two loop $\chi PT$ results.Comment: 20 pages, 7 figs, to appear in Phys. Rev.

Starting a Laparoscopic Surgery Programme in the Second Largest Teaching Hospital in Ghana

Background: Komfo Anokye Teaching Hospital (KATH) is the second  largest hospital in Ghana. Two years have elapsed after performance of the first laparoscopic cholecystectomy.Objectives: To examine our experience and lessons learned.Design: Retrospective review.Setting: Komfo Anokye Teaching Hospital (KATH). Subjects: We reviewed leadership support, the role of a surgeon champion, training of physician and OR staff, influence of surgeons from outside Ghana and equipment status. The results of laparoscopic cholecystectomies performed from 2010-2012 were compared with information available from open cholecystectomies over the same period.Results: Evidence of leadership support included equipment purchase and invitation of outside experts yearly from 2008. A KATH surgeon champion was identified in 2010. A dedicated OR team received training and exhibited excellent ownership of equipment preparation. Since 2010, 25 laparoscopic cholecystectomies have been performed, 17 independently by a single surgeon. Average operative time was 1.41 hours and length of stay (LOS) 1.5 days. Conversion rate was 4.0%(1/25). Complication rate was 20.0%(5/25), none involving haemorrhage or injuries to bile ducts or bowel. Median patient satisfaction score was 5 on a scale of 1-5 where 5 is most satisfied. Complication rates and hospital stay were lower than for open cholecystectomy (20.0%vs34.5%, p>0.05 and 1.5days vs 6.6days, p<0.001 respectively). Operative times were on average 27min onger for laparoscopic cholecystectomy (p<0.01).Conclusion: Laparoscopic cholecystectomy at KATH has become a reality with less complications rates, shorter LOS, and trends towards improved patient satisfaction. Expanding laparoscopic surgery in Ghana requires its inclusion into residency training programmes and public education about its benefits for both patients and physicians

Impact of dielectric separation on transition point and accessible flow enthalpy of inductive plasmas

In order to develop inductive electric propulsion systems towards flight-ready status, an investigation into the influence of the dielectric separation between plasma and inductive coil has been conducted. This was completed by varying the wall thickness of the thruster discharge tube. The investigation assessed discharges of argon and an argon-nitrogen mixture. Additionally, results of a similar investigation utilising air have been included for comparison. The sum of these investigations showed two contrasting trends. The argon condition exhibited a preference for thicker walls, with transitions to the higher inductive regime occurring at lower input powers with increasing wall thickness. Results for Ar:N2 and air showed the opposite, with system thermal power increasing with decreasing wall thicknesses. This behaviour has been proposed to include contributions of both the mechanical dielectric separation caused by the choice of chamber wall thickness, and the gasdynamic dielectric separation owing to the discharge thermal boundary laye