Trajan's Forum (Hemicycle) and Via Biberatica (Trajan's Markets): An HHpXRF Study of the Provenance of Lava Paving in Ancient Rome (Italy)

This paper reports on geochemical data collected using a He-enabled Hand-Held portable XRF (HHpXRF) from lava paving stones in Trajan’s Forum Hemicycle and the Via Biberatica (Rome). Issues relating to HHpXRF field use and calibration are also addressed in detail. Using this instrument 355 analyses of the paving stones were collected and the data was processed using the standard techniques of igneous petrology and petrography. Provenancing was based on comparisons between the HHpXRF data and geological data from the abundant literature on Roman volcanic rocks. These comparisons placed the provenance of the paving stones in the Colli Albani, southeast of Rome. Further analysis using Zr/Y vs Nb/Y discriminant diagrams suggests that the paving stones were quarried from two sources both of which are represented in Trajan’s Forum and the Via Biberatica. The diagrams suggest that the sources lie within the Faete and Vallerano lava complexes. The latter were probably transported to the construction site by barge on the River Tiber and the former were easily accessible by carts along the Via Appia. The study establishes the potential of HHpXRF equipment for non-destructive analysis of paving stones both in Rome and at other sites in central Italy and challenges a number of assumptions about the supply of building materials to Rome based on intuition alone

Laminar and turbulent dissipation in shear flow with suction

The rate of viscous energy dissipation in a shear layer of incompressible Newtonian fluid with injection and suction is studied by means of exact solutions, nonlinear and linearized stability theory, and rigorous upper bounds. For large enough values of the injection angle a steady laminar flow is nonlinearly stable for all Reynolds numbers, while for small but nonzero angles the laminar flow is linearly unstable at high Reynolds numbers. The upper bound on the energy dissipation rate—valid even for turbulent solutions of the Navier-Stokes equations—scales precisely the same as that in the steady laminar solution with regard to the viscosity in the vanishing viscosity limit. Both the laminar dissipation and the upper bound on turbulent dissipation display scaling in which the energy dissipation rate becomes independent of the viscosity for high Reynolds numbers. Hence the laminar energy dissipation rate and the largest possible turbulent energy dissipation rate for flows in this geometry differ by just a prefactor that depends only on injection angle. This result establishes the sharpness of the upper bound’s scaling in the vanishing viscosity limit for these boundary conditions, and this system provides an analytic illustration of the delicacy of corrections to scaling (e.g., logarithmic terms as appearing in the “law of the wall”) to perturbations in the boundary conditions. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87605/2/497_1.pd

Energy dissipation in a shear layer with suction

The rate of viscous energy dissipation in a shear layer of incompressible Newtonian fluid with injection and suction is studied by means of exact solutions, nonlinear and linearized stability theory, and rigorous upper bounds. The injection and suction rates are maintained constant and equal and this leads to solutions with constant throughput. For strong enough suction, expressed in terms of the entry angle between the injection velocity and the boundaries, a steady laminar flow is nonlinearly stable for all Reynolds numbers. For a narrow range of small but nonzero angles, the laminar flow is linearly unstable at high Reynolds numbers. The upper bound on the energy dissipation rate—valid even for turbulent solutions of the Navier–Stokes equations—scales with viscosity in the same way as the laminar dissipation in the vanishing viscosity limit. For both the laminar and turbulent flows, the energy dissipation rate becomes independent of the viscosity for high Reynolds numbers. Hence the laminar energy dissipation rate and the largest possible turbulent energy dissipation rate for flows in this geometry differ by only a prefactor that depends only on the angle of entry. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69712/2/PHFLE6-12-8-1955-1.pd

Antimicrobial resistance in coagulase-positive staphylococci isolated from companion animals in Australia: a one year study

Published: April 21, 2017Methicillin-resistant coagulase-positive staphylococci (CoPS) have become increasingly recognised as opportunistic pathogens that limit therapeutic options in companion animals. The frequency of methicillin resistance amongst clinical isolates on an Australia-wide level is unknown. This study determined antimicrobial susceptibility patterns for CoPS isolated from clinical infections in companion animals (dogs, cats and horses) as part of the first nation-wide survey on antimicrobial resistance in animal pathogens in Australia for a one-year period (January 2013 to January 2014). Clinical Staphylococcus spp. isolates (n = 888) obtained from 22 veterinary diagnostic laboratories were identified by MALDI-TOF mass spectrometry and subjected to antimicrobial susceptibility testing for 16 antimicrobials, representing 12 antimicrobial classes. Potential risk factors associated with methicillin resistance in Staphylococcus pseudintermedius isolates from dogs were analysed based on demographic factors and clinical history, including gender, age, previous antimicrobial treatment, chronic and/or recurrent diseases and site of infections. The most commonly identified CoPS were S. pseudintermedius (70.8%; dogs n = 616, cats n = 13) and S. aureus (13.2%, horses n = 53, dogs n = 47 and cats n = 17). Overall, the frequency of methicillin resistance among S. pseudintermedius (MRSP) and S. aureus (MRSA) was 11.8% and 12.8%, respectively. MRSP isolates were strongly associated with resistance to fluoroquinolones (OR 287; 95%CI 91.2-1144.8) and clindamycin (OR 105.2, 95%CI 48.5-231.9). MRSA isolates from dogs and cats were also more likely to be resistant to fluoroquinolones (OR 5.4, 95%CI 0.6-252.1), whereas MRSA from horses were more likely to be resistant to rifampicin. In multivariate analysis, MRSP-positive status was significantly associated with particular infection sites, including surgical (OR 8.8; 95%CI 3.74-20.7), and skin and soft tissue (OR 3.9; 95%CI 1.97-7.51). S. pseudintermedius isolated from dogs with surgical site infections were three times more likely to be methicillin-resistant if cases had received prior antimicrobial treatment. Whilst the survey results indicate the proportion of CoPS obtained from Australian companion animals that are methicillin-resistant is currently moderate, the identified risk factors suggest that it could rapidly increase without adequate biosecurity and infection control procedures in veterinary practice.Sugiyono Saputra, David Jordan, Kate A. Worthing, Jacqueline M. Norris, Hui S. Wong, Rebecca Abraham, Darren J. Trott, Sam Abraha

Risk factors for feline infectious peritonitis in Australian cats

Objective: To determine whether patient signalment (age, breed, sex, and neuter status) are associated with naturally occurring feline infectious peritonitis (FIP) in cats in Australia. Design: A retrospective comparison of the signalment between cats with confirmed FIP and the general cat population. Results: The patient signalment of 382 FIP confirmed cases were compared with the Companion Animal Register of NSW and the general cat population of Sydney. Younger cats were significantly over-represented amongst FIP cases. Domestic crossbred, Persian, and Himalayan cats were significantly under-represented in the FIP cohort while several breeds were over-represented including British Shorthair, Devon Rex, and Abyssinian. A significantly higher proportion of male cats had FIP compared to female cats. Conclusion: This study provides further evidence that FIP is primarily a disease of young cats and that significant breed and sex predilections exist in Australia. This opens further avenues to investigate the role of genetic factors in FIP

Risk factors for feline infectious peritonitis in Australian cats

Objective: To determine whether patient signalment (age, breed, sex, and neuter status) are associated with naturally occurring feline infectious peritonitis (FIP) in cats in Australia. Design: A retrospective comparison of the signalment between cats with confirmed FIP and the general cat population. Results: The patient signalment of 382 FIP confirmed cases were compared with the Companion Animal Register of NSW and the general cat population of Sydney. Younger cats were significantly over-represented amongst FIP cases. Domestic crossbred, Persian, and Himalayan cats were significantly under-represented in the FIP cohort while several breeds were over-represented including British Shorthair, Devon Rex, and Abyssinian. A significantly higher proportion of male cats had FIP compared to female cats. Conclusion: This study provides further evidence that FIP is primarily a disease of young cats and that significant breed and sex predilections exist in Australia. This opens further avenues to investigate the role of genetic factors in FIP

Rotating Convection in an Anisotropic System

We study the stability of patterns arising in rotating convection in weakly anisotropic systems using a modified Swift-Hohenberg equation. The anisotropy, either an endogenous characteristic of the system or induced by external forcing, can stabilize periodic rolls in the K\"uppers-Lortz chaotic regime. For the particular case of rotating convection with time-modulated rotation where recently, in experiment, chiral patterns have been observed in otherwise K\"uppers-Lortz-unstable regimes, we show how the underlying base-flow breaks the isotropy, thereby affecting the linear growth-rate of convection rolls in such a way as to stabilize spirals and targets. Throughout we compare analytical results to numerical simulations of the Swift-Hohenberg equation

On upper bounds for infinite Prandtl number convection with or without rotation

Bounds for the bulk heat transport in Rayleigh–Benard convection for an infinite Prandtl number fluid are derived from the primitive equations. The enhancement of heat transport beyond the minimal conduction value (the Nusselt number Nu) is bounded in terms of the nondimensional temperature difference across the layer (the Rayleigh number Ra) according to Nu ⩽ cRa2/5,Nu⩽cRa2/5, where c<1c<1 is an absolute constant. This rigorous upper limit is uniform in the rotation rate when a Coriolis force, corresponding to the rotating convection problem, is included. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70609/2/JMAPAQ-42-2-784-1.pd

Flat photonic bands in guided modes of textured metallic microcavities

M. G. Salt and William L. Barnes, Physical Review B, Vol. 61, pp. 11125-11135 (2000). "Copyright © 2000 by the American Physical Society."A detailed experimental study of how wavelength-scale periodic texture modifies the dispersion of the guided modes of λ/2 metal-clad microcavities is presented. We first examine the case of a solid-state microcavity textured with a single, periodic corrugation. We explore how the depth of the corrugation and the waveguide thickness affect the width of the band gap produced in the dispersion of the guided modes by Bragg scattering off the periodic structure. We demonstrate that the majority of the corrugation depths studied dramatically modify the dispersion of the lowest-order cavity mode to produce a series of substantially flat bands. From measurements of how the central frequency of the band gap varies with direction of propagation of the guided modes, we determine a suitable two-dimensional texture profile for the production of a complete band gap in all directions of propagation. We then experimentally examine band gaps produced in the guided modes of such a two-dimensionally textured microcavity and demonstrate the existence of a complete band gap for all directions of propagation of the lowest-order TE-polarized mode. We compare our experimental results with those from a theoretical model and find good agreement. Implications of these results for emissive microcavity devices such as light-emitting diodes are discussed

Vacuum Induced Coherences in Radiatively Coupled Multilevel Systems

We show that radiative coupling between two multilevel atoms having near-degenerate states can produce new interference effects in spontaneous emission. We explicitly demonstrate this possibility by considering two identical V systems each having a pair of transition dipole matrix elements which are orthogonal to each other. We discuss in detail the origin of the new interference terms and their consequences. Such terms lead to the evolution of certain coherences and excitations which would not occur otherwise. The special choice of the orientation of the transition dipole matrix elements enables us to illustrate the significance of vacuum induced coherence in multi-atom multilevel systems. These coherences can be significant in energy transfer studies.Comment: 13 pages including 8 figures in Revtex; submitted to PR