The diffraction of elastic waves by an imperfect fusion bond

We consider diffraction by a semi-infinite crack located alonga fusion interface between two differing elastic media. Twotypes of crack, namely open and partially closed cracks, areinvestigated. An open crack is modelled by a stress-free contactboundary condition and a partially closed crack is modelledby a spring contact boundary condition. For the latter, thejump in the stress across the crack is assumed to be proportionalto the jump in the displacement across the crack. This situationarises in, for example, a K-weld where the fine grain of theparent material (for example, ferritic or forged austeniticsteel) is in stark contrast with the coarse-grained weld metal(for example, austenitic weld metal). In the metal weld thedirection of the grain axis varies through the metal. However,diffraction is a local phenomenon and so the austenitic steelis assumed to have a zonal axis so that it may be modelled bya transversely isotropic composite. The ferritic or forged austeniticsteel will be modelled as an isotropic material.     

Direct detection of oxygen intermediates in the non-heme Fe enzyme taurine/alpha-ketoglutarate dioxygenase

The reaction of substrate-bound taurine/alpha-ketoglutarate dioxygenase with O2 has been studied using cryogenic continuous-flow spectroscopy. Transient absorption spectra acquired at -38 degrees C show an exponential decay of a 318-nm chromophore with an apparent rate of 1.3 s-1. The observed optical changes and their kinetics are consistent with the profile of an Fe(IV) species detected recently by M?ssbauer spectroscopy (Price et al., Biochemistry 2003, 42, 7497-7508). Resonance Raman measurement upon excitation at 363.7 nm reveal at least two oxygen isotope-sensitive vibrations at 821/787 cm-1 and 583/555 cm-1 for 16O and 18O derivatives, respectively. An additional mode is likely to be obscured by an ethylene glycol vibration at 865 cm-1 and/or 1089 cm-1. The 821 cm-1 vibration is assigned to the stretching mode of Fe(IV)=O species on the basis of its frequency and isotopic shift amplitude. The 583 cm-1 band is likely to originate from an Fe-O2 precursor of the Fe(IV)=O species, although its structural details are unclear at present.     

ON AVOIDANCE ACTIVITIES IN FISHERY ENFORCEMENT MODELS

Compliance and enforcement in fisheries are important issues from an economic point of view since management measures are useless without a certain level of enforcement. These conclusions come from the well‐established theoretical literature on compliance and enforcement problems within fisheries and a common result is that, it is efficient to set fines as high as possible and monitoring as low as possible, when fines are costless and offenders are risk neutral. However, this result is sensitive to the assumption that fishermen cannot engage in avoidance activities, e.g., activities to reduce the likelihood of being detected when noncomplying. The paper presents a model of fisheries that allows the fishermen to engage in avoidance activities. The conclusions from the model are that, under certain circumstances, fines are costly transfers to society since they not only have a direct positive effect on the level of deterrence, but also an indirect negative effect in the form of increased avoidance activities to reduce the probability of detection. The paper contributes to the literature on avoidance activities by introducing the externality from the illegal behavior as an endogenous effect on other offenders. For an externality, that has an exogenous effect on other actors, Malik shows that fines are only costly transfers for conditional deterrence (when one actor is deterred while another actor is not). For fisheries, we show that fines are also costly transfers under no deterrence (when no agents are deterred).     

Video-rate optical low-coherence reflectometry based on a linear smart detector array

A low-coherence reflectometer based on a conventional Michelson interferometer and a novel silicon detector chip that allows parallel heterodyne detection is presented. Cross-sectional images of 64x256 pixels covering an area of 1.92 mm x 1.3 mm are acquired at video rate and with a sensitivity close to the shot-noise limit. Applications in surface profiling and thickness measurement are demonstrated.     

PIXE‐alpha non‐destructive and in situ compositional investigation of black gloss on ancient pottery

The chemical characterization of the black gloss on ancient pottery is, since several years, the object of different scientific investigations. Among the different typologies of black gloss, the Attic one is the most refined, because it is prepared by using a fine suspension of an illitic clay applied on the surface of the clay body so that, after an oxiding‐reducing‐oxiding firing cycle at high temperature (800–950 °C), it reaches the typical shiny black aspect. Red figure vases were largely produced in South Italy often reaching a high artistic level. This is the case of the Sicilian red figure vases, sometimes called ‘Sicelioti’, whose production began in Sicily around the end of the fifth century BC and continued until the beginning of the third century BC . The aim of this work is to submit and compare a selection of data related to the chemical composition of the surface black gloss of some Attic and Sicilian red figure vases: This has been investigated, and a chemical‐based discrimination has been proposed. The non‐destructive particle‐induced X‐ray emission‐alpha portable spectrometer was used. The results, carried out in situ at the ‘Paolo Orsi’ Archaeological Museum in Syracuse (Sicily), together with the ones recently obtained in similar analyses at the Archaeological Museum of Catania University, confirmed the compositional stability of Attic vase black gloss and indicated that in a well‐defined time period, the chemical composition of the Sicilian black gloss decorations is very stable and superimposable with that of the contemporary Attic artifacts. Copyright © 2016 John Wiley & Sons, Ltd.     

Orthogonal Polynomials and Second-order Differential Equations

We show that a sequence of polynomials can be eigenfunctionsof a second-order differential operator only under severe restrictions.     

Lattice dynamics of InAs under hydrostatic pressures

The lattice dynamics of InAs under variable hydrostatic pressures is investigated on the basis of an ‘11-parameter’ rigid-ion model (RIM). The calculated phonon dispersion curves are in satisfactory agreement with the neutron scattering data (available for the TA modes only) measured at room temperature and atmospheric pressure. The one- and two-phonon densities of states functions and mode Gruneisen parameters have been computed at two arbitrary hydrostatic pressures. The effect of high pressure on the phonon dispersion curves is shown to lead to a typical ‘softening’ in the transverse acoustic modes and eventually to a phase trnasformation of the compound.