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In situ burning (ISB) hasn't been widely used for offshore oil spill response for various reasons. We present a feasibility study for a new ISB method - the Burning Tongue (BT) concept. We conducted scaled experiments in the Ohmsett wave tank to demonstrate its feasibility. We produced a 35-m long "tongue" of burnable oil (average oil thickness 4.2 mm - above the thickness needed for ISB) by towing a conventional boom (with a 12″ (0.3 m) deep skirt) partially filled with crude oil and then released the oil through a 6″ (0.15 m) wide opening at the apex. We found that the boom movement produced a convergence zone just downstream that kept released oil thick and also pulled oil that entrained under the boom skirt into the thick "tongue" of oil. CFD modeling was performed to explain the flow hydrodynamics and the formation of the convergence zone, which indicates the phenomenon is universal. We used small harbor boom only partially filled with oil for this study and believe that a full-scale marine boom filled with oil would achieve an even thicker "burning tongue." The BT concept could make ISB more widely used for oil spill response in offshore areas.

In-situ burning (ISB) is an important tool to remove oil from the environment. During ISB, it is important to know the volume reduction of oil for the overall accounting of the spilled oil, as a metric for operational decisions, and to account for the ISB portion of the oil budget. The burn rate depends on the type of oil, degree of emulsification and weathering, estimated thickness, weather conditions, and size of the burn area. Furthermore, each spill has a unique physical environment and oil properties that affect burn efficiency and rate. The volume of oil consumed during ISB is typically computed using a manual, coarse, time integration of the instantaneous burn area based on visual observations and a characteristic burn rate. The area is typically estimated in the field using known boom geometry and visual inspection of the fire-water interface, and recorded manually. We have developed methods to measure the instantaneous consumption of burning oil and thus the oil burn rate by integrating direct measurements of thickness using acoustics sensors in the water under the slick with direct measurements of the area of the burning oil using infrared and visible light images from cameras above the burning oil. Data were collected during the burning of several oils and petroleum products including ANS, rock, diesel, and hexane. The acoustic thickness measurement took into account the high temperature gradient in the oil and combined with multi camera automated burn area estimates yielded an instantaneous measurement of the volume of oil consumed while burning. We were able to identify the buildup of the burn, the active burning phase, and in the case of confined burns the vigorous burning phase. Knowing the instantaneous thickness and surface area during burning allowed us to directly calculate the burn rate and to study the dynamics of ISB. We are working on validating the burn rate and efficiency with direct measurements of the weight of the oil and residue before, during, and after burning. The authors believe these are the first direct measurements of slick thickness using acoustics during ISB.

This dissertation reports results from studies of the interactions between the microstructure/macrostructure of titanium alloys and propagating ultrasonic waves. Attention is focused on the interactions which cause backscattering and attenuation. Experimental studies will be reported which show that the phase aberration contribution to attenuation does not remove energy from the propagating beam, and a physical picture is developed. A simple ray model which encompasses the ideas presented in the physical picture is used to predict attenuation for propagation in single phase materials with elongated grains. In addition, a general theory for attenuation that includes some degree of multiple scattering is presented that can allow for texture effects and duplex microstructures in its most general form. Numerical predictions from the general attenuation theory and an existing backscattering theory are then compared with experimental measurements of the attenuation and backscattering coefficient in a Ti-6Al-4V specimen that contains elongated macrograins consisting of colonies that are modeled as ellipsoids. Agreement between the experimental and theoretical determination of the backscattering coefficient is extremely good if the effects of texture is included. Agreement with attenuation is favorable.

Gamma-glutamyltransferase (GGT) has been recently identified as a bone-resorbing factor. The aim of this study was to investigate the association between plasma GGT fractions levels and bone quality. Plasma GGT fractions were analysed by gel-filtration chromatography. Bone quality was established quantitatively by two micro-CT derived microarchitectural parameters: the BV/TV (mineralised bone volume/total volume), and the SMI (structure model index) that describes the rod-like (low resistant) or plate-like (high-resistant) shape of bone trabeculae. We enrolled 93 patients hospitalised for elective total hip replacement (group Arthrosis, n=46) or for proximal femoral fracture (group Fracture, n=47). Patients within the first quartile of BV/TV (Q1, osteoporotic patients, n=6) showed higher levels of b-GGT fraction [median (min-max): 3.37 (1.42–6.81)] compared to patients with normal bone density (fourth quartile Q4, n=10; 1.40 (0.83–4.36); p=0.0393]. Also, according to SMI, b-GGT value was higher in the subgroup with bone fragility [Q1, n=8: 1.36 (0.43–4.36); Q4, n=8: 5.10 (1.4 –7.60); p=0.0117]. In conclusion, patients characterised by fragile bone structure showed specifically higher levels of plasma b-GGT activity thus suggesting fractional GGT analysis as a possible biomarker in the diagnosis of osteoporosis.

Summary The past decade has seen strong controversy concerning the upper bounds for weed eradication. Over this period, two of the most ambitious weed eradication attempts ever have failed. These have, however, provided rich data sets that have supported a productive and highly collaborative research effort. I review this research and present a new algorithm for assessing eradication feasibility, based upon time to maturation, seedbank persistence and membership of one of two contrasting dispersal functional groups. Eight ‘eradication syndromes’ are identified and their relative eradication feasibilities indicated. The syndrome with the highest feasibility includes species that combine long juvenile periods and low seedbank persistence with short-distance and/or human-mediated dispersal. At first glance, this may not be a common syndrome. The syndrome with the lowest feasibility comprises plants that combine a short juvenile period and high seedbank persistence with abiotic or non-human-mediated biotic dispersal. It includes a number of aquatic perennials that can be dispersed over large distances by floodwaters. Projected costs for a programme targeting a plant species should reflect its syndrome membership. Improved cost estimates will support better decision-making with regard to programme initiation, maintenance and termination; models are available that can provide estimates of eradication programme duration and cost. Whether eradication has much of a future as a weed invasion management strategy will likely rest upon more timely, better-informed and shrewder target selection.

To help minimize the effects of oil spills on marine environments, chemical dispersants are used to disperse the oil in the water column so the oil can be consumed by naturally occurring bacteria. During the Deepwater Horizon incident, 1.1 million gallons of dispersant were injected directly into the flowing plume of oil and natural gas over 1500 meters deep. Dispersant's main effect is to decrease the surface tension at the oil-water interface causing the oil to form droplets smaller than ~70 microns so they can remain in the water column. Currently the efficacy of aerial applied dispersants on surface slicks is determined by measuring the droplet size decrease using a Laser In-Situ Scattering Transmissometer (LISST) or by detecting the oil in the water column using fluorometers. LISST instruments are limited to dilute mixtures, below ~500 ppm, because the LISST signal saturates for concentrated mixtures, and their windows can become occluded by oil and biofilms. Fluorometers only measure oil concentration; thus they cannot distinguish between naturally dispersed oil droplets, which can float back to the surface, from chemically dispersed oil droplets, which will remain in the water column to be naturally biodegraded. When gas is present as was the case in the Deepwater Horizon incident where it was estimated that the plume consisted of ~22% natural gas, the LISST cannot distinguish between oil droplets and gas bubbles and thus is not able to track the effectiveness of dispersants in the presence of gas. Acoustic measurements overcome the problems associated with the LISST and fluorometers and are ideal for applications subsurface near a blowout and for low ppm levels expected for surface slicks. One of the key features of the sound wave propagating through the water is the scattering at the interface between the water and object. In previous work we showed the proof of concept to measure the average oil droplet size using acoustic. We used the resonance behavior of the gas bubbles to identify them and separate their contribution to the measured acoustic scattering for various oil and dispersant combinations . We developed acoustic scattering and resonance measurements to track the size of oil droplets in the presence of gas during subsurface releases at SINTEF and in Ohmsett's large wave tank.

International audience; While the effects of an invasive alien plant that has become dominant in a community may seem obvious, there are few studies that attempt to understand how impacts vary according to the characteristics of invaders and recipient communities. For this purpose, the vegetation of invaded and non-invaded plots was sampled for eight different invasive species in a variety of habitats within the French continental Mediterranean region. Most of the observed impact variation was species-specific, with greater effects on community-level metrics found for Carpobrotus spp. and Reynoutria x bohemica and lower effects for Amorpha fruticosa, Ambrosia artemisiifolia and Phyla filiformis. Some trends were consistent with competition-driven processes, with higher impact found in the presence of rhizomatous and creeping perennial invasive species compared to annuals, or in habitats with sparse vegetation. The importance of community characteristics such as the cover of the invasive plant or the differences in cover between the invader and the native dominant species confirmed previous results obtained in Central Europe. Therefore, such variables, easy to measure and with a generic value, could be profitably integrated into risk assessment methods to improve the prediction of the most threatened habitats. Beyond the overall decline in species diversity, the presence of some invasive species was associated with significant changes in species composition, with a filtering toward more shade-tolerant and nitrophilous ruderal species. Managers should consider replacement of resident species by species with different ecological preferences together with simple community-level metrics, to decide whether management is justified.

Exotic and invasive woody vines are major environmental weeds of riparian areas, rainforest communities and remnant natural vegetation in coastal eastern Australia, where they smother standing vegetation, including large trees, and cause canopy collapse. We investigated, through glasshouse resource manipulative experiments, the ecophysiological traits that might facilitate faster growth, better resource acquisition and/or utilization and thus dominance of four exotic and invasive vines of South East Queensland, Australia, compared with their native counterparts. Relative growth rate was not significantly different between the two groups but water use efficiency (WUE) was higher in the native species while the converse was observed for light use efficiency (quantum efficiency, AQE) and maximum photosynthesis on a mass basis (Amax mass). The invasive species, as a group, also exhibited higher respiration load, higher light compensation point and higher specific leaf area. There were stronger correlations of leaf traits and greater structural (but not physiological) plasticity in invasive species than in their native counterparts. The scaling coefficients of resource use efficiencies (WUE, AQE and respiration efficiency) as well as those of fitness (biomass accumulated) versus many of the performance traits examined did not differ between the two species-origin groups, but there were indications of significant shifts in elevation (intercept values) and shifts along common slopes in many of these relationships – signalling differences in carbon economy (revenue returned per unit energy invested) and/or resource usage. Using ordination and based on 14 ecophysiological attributes, a fair level of separation between the two groups was achieved (51.5% explanatory power), with AQE, light compensation point, respiration load, WUE, specific leaf area and leaf area ratio, in decreasing order, being the main drivers. This study suggests similarity in trait plasticity, especially for physiological traits, but there appear to be fundamental differences in carbon economy and resource conservation between native and invasive vine species.

Aim: To develop a surveillance support model that enables prediction of areas susceptible to invasion, comparative analysis of surveillance methods and intensity and assessment of eradication feasibility. To apply the model to identify surveillance protocols for generalized invasion scenarios and for evaluating surveillance and control for a context-specific plant invasion. Location: Australia. Methods: We integrate a spatially explicit simulation model, including plant demography and dispersal vectors, within a Geographical Information System. We use the model to identify effective surveillance protocols using simulations of generalized plant life-forms spreading via different dispersal mechanisms in real landscapes. We then parameterize the surveillance support model for Chilean needle grass [CNG; Nassella neesiana (Trin. & Rupr.) Barkworth], a highly invasive tussock grass, which is an eradication target in south-eastern Queensland, Australia. Results: General surveillance protocols that can guide rapid response surveillance were identified; suitable habitat that is susceptible to invasion through particular dispersal syndromes should be targeted for surveillance using an adaptive seek-and-destroy method. The search radius of the adaptive method should be based on maximum expected dispersal distances. Protocols were used to define a surveillance strategy for CNG, but simulations indicated that despite effective and targeted surveillance, eradication is implausible at current intensities. Main conclusions: Several important surveillance protocols emerged and simulations indicated that effectiveness can be increased if they are followed in rapid response surveillance. If sufficient data are available, the surveillance support model should be parameterized to target areas susceptible to invasion and determine whether surveillance is effective and eradication is feasible. We discovered that for CNG, regardless of a carefully designed surveillance strategy, eradication is implausible at current intensities of surveillance and control and these efforts should be doubled if they are to be successful. This is crucial information in the face of environmentally and economically damaging invasive species and large, expensive and potentially ineffective control programmes.

To investigate the effects of soil type on seed persistence in a manner that controlled for location and climate variables, three weed species—Gomphocarpus physocarpus (swan plant), Avena sterilis ssp. ludoviciana (wild oat) and Ligustrum lucidum (broadleaf privet)—were buried for 21 months in three contrasting soils at a single location. Soil type had a significant effect on seed persistence and seedling vigour, but soil water content and temperature varied between soils due to differences in physical and chemical properties. Warmer, wetter conditions favoured shorter persistence. A laboratory-based test was developed to accelerate the rate of seed ageing within soils, using controlled superoptimal temperature and moisture conditions (the soil-specific accelerated ageing test, SSAAT). The SSAAT demonstrated that soil type per se did not influence seed longevity. Moreover, the order in which seeds aged was the same whether aged in the field or SSAAT, with L. lucidum being shortest-lived and A. sterilis being longest-lived of the three species.

The propagation of elastic waves in polycrystals is a classical topic with a rich history of research, with primary focus on attenuation in single phase materials with randomly oriented, equiaxed grains. Over the last decade, the need to nondestructively evaluate the degree of damage of engineering components has led to extension of the classical understanding to a number of more complex cases. These motivations include the desire to understand how the noise backscattered from microstructure, and limiting flaw detectability, is controlled by the measurement configuration and microstructure of the material, the desire to use the understanding of attenuation and backscattering in designing improved inspections and in assessing their capability as quantified by probability of detection, and the desire to develop improved procedures for characterizing microstructures. This paper provides an overview of this work. A brief review of the classical understanding of how elastic waves are attenuated and backscattered by scattering from grain boundaries in randomly oriented polycrystals is first presented. This is followed by the results of recent experiments and analysis concerning how these phenomena change in engineering materials with more complex microstructures. For single phase polycrystals, the paper presents results verifying the classical theories in copper, showing how these theories can be used to determine single crystal elastic constants from measurements in alloy polycrystals, demonstrating this technique on nickel-base superalloys, and providing evidence of multiple scattering effects that are not accounted for in the classical, first-order theory. Additional results are presented in titanium alloys having duplex microstructures that demonstrate the existence of fluctuations of beam amplitude and phase, and a simple two-dimensional theory is presented which qualitatively explains the results. The paper concludes with the presentation of some pitch–catch (bi-static) experiments that clearly illustrate the role of multiple scattering.

A novel sensor concept has been developed for measuring the consistency, the degree of refining, the water retention value (WRV), and the consistency of wood pulp during the refining process. The measurement time is less than 5 minutes and the sensor can operate in a slip-stream of the process line or as an at-line instrument. The consistency is obtained from a calibration, in which the attenuation of ultrasound through the pulp suspension is measured as a function of the solids weight percentage. The degree of refining and the WRV are determined from settling measurements. The settling of a pulp suspension (consistency less than 0.5 Wt%) is observed, after the mixer that keeps the pulp uniformly distributed is turned off. The attenuation of ultrasound as a function of time is recorded and these data show a peak, after a certain delay, defined as the “peak time.” The degree of refining increases with the peak time, as demonstrated by measuring pulp samples with different degrees of refining. The WRV can be determined using the relative peak time, defined as the ratio T2/T1, where T1 is an initial value of the peak time and T2 is the value after additional refining. This methodmore » offers an additional WRV test for the industry, because the freeness test is not specific for the WRV.« less

When sown over consecutive years at two sites in the Western Australian wheatbelt, a maximum of 34.5% of viable Chondrilla juncea seeds gave rise to emerged seedlings. During the early winter months at one site, waterlogging on a duplex soil type led to an almost complete failure of emergence. Very low levels of seed persistence (maximum 3.1%) between years were noted. The protection provided by stubble enhanced the survival of C. juncea seedlings which emerged during May, but for seedlings which emerged later, the effects of stubble upon seedling survival were strongly dependent upon the abundance of the red-legged earth mite (Halotydeus destructor) At the observed densities of winter annuals, the presence of seedlings and young plants appeared to reduce seedling mortality in C. juncea. Young plants of C. juncea were highly susceptible to simulated cultivation practices until 12 weeks following emergence. It is argued that seedling establishment of C. juncea is most likely to occur during the pasture phase of crop/pasture rotations in the Western Australian wheatbelt and that pastures immediately following cropping years are most prone to invasion.

Survivorship of first-year plants of Chondrilla juncea was considerably higher on a deep yellow sand than on a yellow duplex soil. Mortality on the latter soil was associated with drying of the Al horizon during early summer. No plants produced seeds in their first year of growth on the duplex soil. However, during both years of the study, first-year individuals of both forms of C. juncea produced viable seeds when growing on the deep sand. Higher population growth rates could be expected on deep sands, owing to a combination of earlier reproduction and greater survivorship through the first summer. It is suggested that whilst the entire wheatbelt might be climatically suitable for C. juncea, the invasive potential of this weed might be restricted by edaphic characteristics over large areas.

The Protoaurignacian culture is pivotal to the debate about the timing of the arrival of modern humans in western Europe and the demise of Neandertals. However, which group is responsible for this culture remains uncertain. We investigated dental remains associated with the Protoaurignacian. The lower deciduous incisor from Riparo Bombrini is modern human, based on its morphology. The upper deciduous incisor from Grotta di Fumane contains ancient mitochondrial DNA of a modern human type. These teeth are the oldest human remains in an Aurignacian-related archaeological context, confirming that by 41,000 calendar years before the present, modern humans bearing Protoaurignacian culture spread into southern Europe. Because the last Neandertals date to 41,030 to 39,260 calendar years before the present, we suggest that the Protoaurignacian triggered the demise of Neandertals in this area.

Computed tomography (CT) is a diagnostic technique that allows reconstructing cross sections of a patient's body, providing detailed information about structure and anatomy of organs and, to some extent, also of their functionality. This chapter will focus on the basic principles and technological evolution of CT, starting from the concept of tomography and the fundamentals of image reconstruction from projections. The improvements that have led to the current configuration of modern multislice CT and cone-beam CT scanners are illustrated, along with the most important dose reduction techniques and a concise review of common image artifacts and possible strategies for their correction. Finally, the basic principles of cardiac CT and CT perfusion are described.

Parthenium or famine weed (Parthenium hysterophorus L.) is an annual plant originating from the Americas, which is a major invasive alien plant in almost all continents. While the deleterious impacts of the species on agriculture, human and animal health have been well documented, information on the pathways of entry of the species is only occasionally mentioned in the literature. As this invasive alien plant is only recorded as established in Israel and Egypt within the Euro-Mediterranean region, the European and Mediterranean Plant Protection Organization identified P. hysterophorus as an emerging threat. EPPO therefore performed a Pest Risk Analysis on this species to assess the risk it represents and to consider appropriate management options. The EPPO Pest Risk Analysis main outputs are summarized in this article, indicating the probability of entry of the species via the different pathways within the EPPO region, its probabilities of establishment and spread, and the magnitude of its potential agricultural, environmental and social impacts.

Grain size is a key property that is carefully controlled during processing to create specific mechanical properties and reliability in final components. Achieving specific grain sizes is especially important in aircraft engines where temperatures can range from 260°C at the bore to 704°C at the rim, creating fatigue cracking in the bore and creep damage in the rim region. These competing failure mechanisms led to nickel alloy disks possessing fine-grains, ~5 microns in the bore and coarse-grains, ~80 micron in the rim. We created an automated ultrasonic measurement tool which calculates grain size from ultrasonic backscattering measurement. The tool unifies the entire process including controlling the ultrasonic scanner, data acquisition, experimental and theoretical backscattering calculations, numerical optimization to obtain grain size, and visualization. We tested our tool on IN718, Waspaloy, Rene 88 and Alloy 10. Our automated “Ultrasonic Metallography Tool” produced a map of the grain size where the color scale is the grain size. The authors believe this is the first time such a map has been generated automatically from ultrasonic backscattering measurements. Our results compare favorably with traditional metallography agreeing to within 2 microns for some alloys.

It is well known that a monochromatic X-ray source with an energy optimized for the organ thickness to be imaged could result in a better image quality in transmission radiology. In this paper we present the preliminary investigation for the implementation of this technique in computer tomography (CT) imaging. The detection system is based on a 1 mm thick silicon pixel detector bump bonded to a VLSI read-out, Medipix2. This detector ensures a good detection efficiency (46%) in the used energy range (60 kVp) with a good spatial resolution that arises from a 55 μm square pixel. The Medipix2 read-out electronics is not only a single photon counting system, but has also the capability of dual-energy threshold, that allows us to detect only photons that are in a chosen energy window. In this paper we present the results obtained in CT imaging of small samples, by selecting various energy windows within a standard X-ray tube spectrum so as to maximize the differentiation between significant attenuation coefficients. This study is preliminary for a future development of a dual-energy CT that could add functional information to the morphological information that is obtained in a CT examination.

Computed Tomography (CT) gives 3-D morpho logical images of the object under test. Anatomica information from CT can be used to compensate the limits of radionuclide imaging techniques. First of al it can help in physically localizing the uptake site within the body of the animal, thus allowing the ana tomical identification of the site. The CT scan also helps in performing more accurate radionuclide quan tification studies. These are usually performed by selecting a region-of-interest on the SPECT (or PET image: the higher spatial resolution of the CT allow more precise determination of the boundary of the ROI, and therefore of the number of counts within the ROI.

Parthenium hysterophorus L. seeds were buried at a depth of 5 cm for periods of 2-24 months to determine their longevity. The majority (73.7%) of these seeds were still viable after 24 months of burial. The remainder could not be recovered (18.0%) or were no longer viable (8.3%). There was a log-linear decline in persistence of germinable seeds over time, which indicated a constant rate of loss and a half-life of about 6 years. Seedling emergence from surface-sown seeds was also studied. Although there was considerable rainfall (31 mm), seedlings did not emerge during the first month of this experiment. In the succeeding 3 months, there was substantial seedling emergence after rainfall, and 51.4% of seeds had germinated by the end of the fourth month. After 5 months had passed, further seedling emergence was not detected, and intact seeds could not be located. These findings suggest that seed incorporation into the soil is important to the longterm persistence of P. hysterophorus seeds. In an initial test of germination, unburied seeds from the same seed lot exhibited a degree of innate dormancy, and this may explain the delayed germination observed in the surface-sown seeds. In the seed burial and recovery experiment, innate dormancy was lost after 2 months of burial in the field, although in situ germination of buried seed remained low for at least 24 months. Therefore, it appears that more than one dormancy mechanism may contribute to the persistence of P. hysterophorus seeds.

The use of sound waves in oceanographic environments is well established including active sonar applications for mapping seafloors, for submarine detection, and for passive listening. Acoustic waves have been used for many years to study the ocean, including detecting and identifying objects in the water column, and the measuring the seafloor and sub seafloor properties. One of the key parameters of the acoustic field is the amplitude of the wave which scatters from the seafloor or from objects in the water column. The amplitude, time of flight, and frequency response can be used to map the seafloor, measure current flow, or to detect and classify objects in the water column. In addition to these standard uses, acoustics can also be used to size particulates including sediment, oil droplets and gas bubbles in the water. Our particular application for this work is to detect, classify, and size sediment particles and separately, oil droplets suspended in the water column using knowledge of the acoustic backscattering and attenuation. Specifically, we have measured and separated the absorption, single scattering and multiple scattering contributions to attenuation measurements. Our results show that the absorption dominates the attenuation at low ka values ∼1 with a transition between theses ranges depending on the concentration of the suspensions. The physics has been proven out on silica particles in water and work is ongoing on suspended sediment and suspensions of oil droplets.

While the Acoustic Doppler Velocimeter (ADV) is designed to determine fluid velocity, it is important to recognize that it is actually the velocity of the scatterers themselves that is measured. Thus in a calibration tank designed to relate sediment-induced backscatter to sediment concentration, the vertical velocity registered by an ADV at a given point is actually the true fluid velocity plus the sediment's settling velocity. And absent net vertical volume flux, the average vertical velocity registered by an ADV across a horizontal plane is equal to the mean sediment settling velocity. For this study, a series of ADV calibrations were run in a 118-liter re-circulating tank for six sand sizes between 63 and 150 microns. A grid of ADV measurements distributed in a horizontal plane across the tank revealed that the mean vertical velocity registered by the ADV in each case was indeed consistent with each grain size's settling velocity as independently measured by a “rapid sand analyzer” laboratory settling tube. In addition, a systematic increase in the proportionality between sand concentration and backscatter was observed with increasing grain size.

Experimental introductions of the annual Emex australis were made in two consecutive years at each of three sites in southern Western Australia. Introductions differed in relation to the numbers of seeds involved (n = 1, 2,4, 8 or 16) and whether seeds were buried or surface sown. Fates of the introductions were monitored for 30 months. Successful introductions were defined as those where at least one viable seed was produced. Generally, introduction success increased with the number of seeds involved and with seed burial. However, major departures from these trends were observed at one site in the second set of introductions. Most recruitment and most seed production occurred during the first growing season following introduction. The number of seeds produced over the 30 month period usually increased with increasing size of introduction. The year of introduction was a highly significant determinant of seed production. Since seedling mortality was low throughout this study, processes affecting seed burial and seed mortality are considered to be the major stochastic factors that influence the colonizing success of Emex australis.

The southern Adriatic basin is the current foredeep of the Albanide fold-and-thrust belt that runs along the eastern boundary of the Adriatic basin and partly owes its remarkable water depth, deeper than 1,000 m, to the Mesozoic palaeogeography of the region. The eastern slope of the southern Adriatic basin is characterized by a thick stack of sedimentary prograding units, fed by sediments coming from the adjacent fold-and-thrust belt, which is still seismically active (e. g. 1979 Montenegro, M = 6. 8). This slope presents extensive evidence of large-scale mass wasting throughout its Quaternary evolution and appears as a destructive slope system affected by progressive retreat. A submarine slide located along the eastern slope of the southern Adriatic basin has been recently characterized with good detail. The slide is of relatively small volume (0. 031 km3) and shows a limited displacement, without major internal disruption. The small volume of the landslide combined with its relatively large water depth (headscarp at about 560 m and deposit at 700 m) result in a limited tsunamigenic potential, that has been assessed numerically by means of a Lagrangian block model as regards the slide motion and through a shallow-water finite-difference code for the tsunami waves propagation. Despite the almost negligible tsunami effects, the studied landslide can be taken as a lower case limit for other events along the scarp, and the observed features concerning the generated wave and its impact on the coast can be considered valid also for bigger events.

Seeds of four Western Australian accessions of Emex australis were stored outside and their germinability tested at 4–6 week intervals for 22 months. Accessions showed cyclical behaviour in germinability, with peaks in autumn/early winter and troughs in spring/summer. There was considerable variation between accessions in dormancy/non-dormancy cycles, but when plants from accessions with contrasting cycles were grown in a common environment, the cycles shown by their seeds were virtually identical. Thus, the parameters of seed dormancy/non-dormancy cycles in E. australis appear to be under environmental control. Only part of an E. australis seed population demonstrated cyclical changes in dormancy status, in contrast to many other annual species whose entire seed populations undergo such changes. Populations also contained individuals which were either continuously dormant or continuously non-dormant following a period of after-ripening. The latter seeds give E. australis the flexibility to recruit opportunistically after summer rainfall events in mediterranean-climate environments.

Summary: Resume: Zusammenfassung Herbicides were applied annually for 3 years to a pasture population of Emex australis Steinh. Herbicide performance was highly variable, with significant effects on weed survival only in single seasons. In most cases, seed bank densities declined monotonically from an initial level of 1900 m−2. Seed banks decreased after seasons when E. australis contributed less than 25% to pasture dry matter. The annual decay rate of the seed bank was estimated to be 70%. Owing to the unreliability of the herbicides when applied at rates low enough to protect pasture legumes, the potential for tactical chemical control of E. australis is limited. Furthermore, it is argued that the potential for strategic chemical control is low, since the species can tolerate periods of population decline. E. australis could be managed more effectively by maintaining high densities of annual grasses and legumes, against which it is a poor competitor. Efficacite herbicide et lutte contre Emex australis dans une pâture annuelle Des herbicides ont ete appliques chaque annee pendant trois ans sur une population d' Emex australis Steinh. dans une pâture. L'efficacite herbi- cide etait tres variable, et les effets significatifs sur la survie des mauvaises herbes ne furent que des evenements uniques, observes lors de saisons isolees. Dans la plupart des cas, les stocks semenciers ont decru de facon monotone a partir d'un niveau initial 1900 m−2. Us decrurent apres les saisons ouE. australis contribuait pour moins de 25%a la matiere seche de la pâture. Le taux de decroissance annuel du stock semencier etait estimeâ 70%. En raison du manque de fiabilite des herbicides lorsqu'ils sont appliques â des doses suffisamment basses pour respecter les legumineuses de la pâture, leur interet pour la lutte chimique a court terme contre E. australis est limite. Leur interet a moyen terme est egale-ment faible car cette espece peut supporter des periodes de declin demographique. On pourrait lutter plus efficacement contre E. australis en maintenant de fortes densites de graminees annuelles et de legumineuses, a l'egard desquelles cette mauvaise herbe est un com-petiteur mediocre. Herbizidwirkung und die Bekampfung von Emex australis auf einjahrigem Weideland Bei jahrlicher Anwendung von Herbiziden uber 3 Jahre hin zur Bekampfung von Emex australis Steinh. war die Wirkung sehr variabel; eine sig-nifikante Wirkung auf das Uberleben des Unkrauts gab es nur in einzelnen Vegetations-perioden. Die Bodensamenbank nahm meistens gleichformig von einem Ausgangsbestand von 1900 m−2 ab. Die Samendichte sank in den Jahren, wo Emex australis weniger als 25% der Trockenmasse der Weidepflanzen ausmachte. Der jahrliche Ruckgang der Lebensfahigkeit der Samen im Boden wurde auf 70% geschatzt. Wegen der Unzuverlassigkeit von Herbiziden, wenn sie zum Schutz der Weide-pflanzen niedrig dosiert werden, sind die Aussichten fur eine chemische Bekampfung dieser Art begrenzt. Auserdem sind langfristige Erfolge auf diese Weise kaum zu erreichen, da die Art zeitweiligen Populationsruckgang ubersteht. Die Verbreitung von Emex australis sollte durch hohe Dichten einjahriger Graser und Leguminosen wirkungsvoller zuruckgedrangt werden konnen, weil sie gegenuber diesen Arten ein schlechter Konkurrent ist.

Background and Aims: Success of invasive plant species is thought to be linked with their higher leaf carbon fixation strategy, enabling them to capture and utilize resources better than native species, and thus pre-empt and maintain space. However, these traits are not well-defined for invasive woody vines. Methods: In a glass house setting, experiments were conducted to examine how leaf carbon gain strategies differ between non-indigenous invasive and native woody vines of south-eastern Australia, by investigating their biomass gain, leaf structural, nutrient and physiological traits under changing light and moisture regimes. Key Results: Leaf construction cost (CC), calorific value and carbon : nitrogen (C : N) ratio were lower in the invasive group, while ash content, N, maximum photosynthesis, light-use efficiency, photosynthetic energyuse efficiency (PEUE) and specific leaf area (SLA) were higher in this group relative to the native group. Trait plasticity, relative growth rate (RGR), photosynthetic nitrogen-use efficiency and water-use efficiency did not differ significantly between the groups. However, across light resource, regression analyses indicated that at a common (same) leaf CC and PEUE, a higher biomass RGR resulted for the invasive group; also at a common SLA, a lower CC but higher N resulted for the invasive group. Overall, trait co-ordination (using pair-wise correlation analyses) was better in the invasive group. Ordination using 16 leaf traits indicated that the major axis of invasive-native dichotomy is primarily driven by SLA and CC (including its components and/or derivative of PEUE) and was significantly linked with RGR. Conclusions: These results demonstrated that while not all measures of leaf resource traits may differ between the two groups, the higher level of trait correlation and higher revenue returned (RGR) per unit of major resource need (CC) and use (PEUE) in the invasive group is in line with their rapid spread where introduced.

Seedling emergence of three weeds (Carduus nutans, Cirsium vulgare and Rumex obtusifolius) and three clovers (Trifolium repens, T. subterraneum and T. pratense) was monitored in gaps of different sizes (0, 2, 6 and 10 cm diameter, plus a 3 m2 bare plot), which were created in a Loliumperenne/T. repens pasture. Clover emergence was greatest in the bare plots, in contrast with the weeds, whose emergence peaked in small or intermediate-sized gaps. Relationships between weed emergence and gap size in glasshouse swards were poorly denned. As a result of trampling by cattle, seedling mortality occurred most rapidly for all species in the bare plots. Very few weeds survived in the other gaps, where there was no detectable effect of gap size upon survivorship. Naturally occurring gaps were most abundant during summer, but their size frequency distributions varied little between spring and autumn. The sizes of almost 95% of the natural gaps were within the range of the experimentally-created gaps. Poor survivorship of weeds within this range, however, suggests that larger gaps are required for regeneration.

Summary Background Ocular complications are amongst many side-effects of interferon based therapy for hepatitis C virus (HCV) infection. Some suggest that diabetic and hypertensive patients are at increased risk of these complications. Aim To determine the frequency of ophthalmological complications related to interferon use. Methods Retrospective analysis of patients undergoing HCV treatment with pegylated interferon α-2a, α-2b or consensus interferon plus ribavirin between 2005 and 2007. All patients underwent a baseline eye examination and any visual complaints during treatment prompted a repeat examination. Data recorded included HCV genotype, treatment duration, interferon type, pre-treatment and on treatment visual complaints, known ocular pathology, and retinal findings at baseline and at follow-up. Results Of 183 patients, 29 (16%) had diabetes and 85 (46%) had hypertension. Seventy-one (38%) received interferon α-2a, 100 (55%) α-2b, and 12 (7%) consensus interferon. Seven (3.8%) had retinal changes on follow-up and treatment was discontinued in 3 (1.6%). Of seven with ocular changes two had hypertension and one had both hypertension and diabetes. Conclusion The incidence of symptomatic retinopathy in HCV patients undergoing interferon therapy appears low and treatment cessation is rarely needed. Furthermore, patients with hypertension and diabetes may not be at higher risk for interferon-induced retinopathy.

The computer program BIOCLIM was used to estimate climatically suitable areas for three weeds which are prohibited entry to New Zealand. For Parthenium hysterophorus, nowhere in New Zealand was predicted to be suitable. Part of the Hawkes Bay Region was predicted to be marginally suitable for Solarium elaeagnifolium. By using the computer program CLIMEX, climates for locations in other countries where Parthenium and Solarium are weedy were examined. Comparisons revealed no close matches with New Zealand locations, suggesting that predictions made on the basis of Australian climatic data were reliable. Thus the need for prohibition is doubtful, especially for Parthenium. For Sorghum halepense, extensive areas on the North Island and parts of the northern and eastern coasts of the South Island could potentially be invaded. Such results support the quarantine status of Sorghum as well as the current eradication campaign targeting this species. It is concluded that BIOCLIM can be used to assist quara...

Summary: Populations of the winter annual Emex australis were established by initiating irrigation at monthly intervals, beginning in mid-summer. Natural seedling densities varied from 100 m−2 when irrigation was begun during late January to almost 700 m−2 when it began at the end of March. Densities were increased by sowing non-dormant seeds, but most sown seeds became dormant when introduced before autumn. Plants which emerged after the earliest irrigation grew most rapidly. Those originating from the latest irrigation grew most slowly, in association with vigorous growth of other annual species. Because it minimizes interspecific competition, early commencement of irrigation, coupled with sowings of nondormant seeds is the best method for establishing E. australis during summer. Maintenance of such populations may enhance the persistence of non-aestivating biological control agents and/or boost their numbers prior to the onset of mass germination. This approach could also prove useful for other winter annuals which are targeted for biological control. Resume: Des populations de l'annuelle hivernale Emex australis ont eteetablies grâce a l'irrigation a intervalles mensuels, a partir de la mi-ete. Les densites de plantules naturelles ont varie de 100 m−2 quand l'irrigation a commence pendant la fin janvier a presque 700 m−2 quand elle a debute fin mars. Les densites ont augmente en semant des graines non dormantes mais la majorite des graines sont entrees en dormance quand elles ont ete introduites avant l'automne. Les plantes qui ont leve apras l'irrigation la plus precoce ont grandi plus rapidement. Celles issues de l'irrigation la plus tardive ont grandi plus lentement, en liaison avec la croissance vigoureuse des autres espaces annuelles. Parce que cela diminue la competition interspecifique, le commencement precoce de l'irrigation, couple avec le semis de graines non dormantes est la meilleure methode pour etablir E. australis pendant l'ete. La maintien de telles populations peut ameliorer la persistance des agents de lutte biologique non estivaux et/ou faire monter leur nombre avant l'apparition du gros de la germination. Cette approche pourrait aussi s'averer utile pour d'autres annuelles hivernales cibles de la lutte biologique. Zusammenfassung: Durch Bewusserung in monatlichen Intervallen, beginnend in der Mitte des Sommers, wurden Populationen des wintereinjuhrigen Emex australis zum Wachstum gebracht. Die naturliche Keimpflanzendichte variierte von 100 m−2 bei Bewusserungsbeginn im sputen Januar bis fast 700 m−2 bei Bewusserung ab Ende Murz. Die Dichte wurde durch Aussaat nichtdormanter Samen erhoht, aber die meisten ausgesuten Samen wurden dormant, wenn sie vor dem Herbst ausgebracht wurden. Am schnellsten wuchsen die Pflanzen, die nach der fruhesten Bewusserung keimten. Die nach der sputesten Bewusserung gekeimten wuchsen, in verbindung mit dem kruftigen Wuchs anderer einjuhriger Arten, am langsamsten. Zur verminderung interspezifischer Konkurrenz ist eine fruhe Bewusserung, verbunden mit der Aussaat nichtdormanter Samen, die beste Methode, um im Sommer Emex australis anzuziehen. Die Bildung solcher Populationen kann die Uberdauerung von biologischen Bekumpfungsorganismen fordern und/oder ihre Zahl vor dem Beginn der normalen Keimung erhohen. Diese Methode konnte sich auch fur andere winterannuelle Arten, die biologisch bekumpft werden sollen, als nutzlich erweisen.

AIM: To compare the yield of adenomas between narrow band imaging and white light when using high definition/magnification. METHODS: This prospective, non-randomized comparative study was performed at the endoscopy unit of veteran affairs medical center in Phoenix, Arizona. Consecutive patients undergoing first average risk colorectal cancer screening colonoscopy were selected. Two experienced gastroenterologists performed all the procedures that were blinded to each other’s findings. Demographic details were recorded. Data are presented as mean ± SEM. Proportional data were compared using the χ2 test and means were compared using the Student’s t test. Tandem colonoscopy was performed in a sequential and segmental fashion using one of 3 strategies: white light followed by narrow band imaging [Group A: white light (WL) → narrow band imaging (NBI)]; narrow band imaging followed by white light (Group B: NBI → WL) and, white light followed by white light (Group C: WL → WL). Detection rate of missed polyps and adenomas were evaluated in all three groups. RESULTS: Three hundred patients were studied (100 in each Group). Although the total time for the colonoscopy was similar in the 3 groups (23.8 ± 0.7, 22.2 ± 0.5 and 24.1 ± 0.7 min for Groups A, B and C, respectively), it reached statistical significance between Groups B and C (P < 0.05). The cecal intubation time in Groups B and C was longer than for Group A (6.5 ± 0.4 min and 6.5 ± 0.4 min vs 4.9 ± 0.3 min; P < 0.05). The withdrawal time for Groups A and C was longer than Group B (18.9 ± 0.7 min and 17.6 ± 0.6 min vs 15.7 ± 0.4 min; P < 0.05). Overall miss rate for polyps and adenomas detected in three groups during the second look was 18% and 17%, respectively (P = NS). Detection rate for polyps and adenomas after first look with white light was similar irrespective of the light used during the second look (WL → WL: 13.7% for polyps, 12.6% for adenomas; WL → NBI: 14.2% for polyps, 11.3% for adenomas). Miss rate of polyps and adenomas however was significantly higher when NBI was used first (29.3% and 30.3%, respectively; P < 0.05). Most missed adenomas were ≤ 5 mm in size. There was only one advanced neoplasia (defined by size only) missed during the first look. CONCLUSION: Our data suggest that the tandem nature of the procedure rather than the optical techniques was associated with the detection of additional polyps’ and adenomas.

Noninvasive measurements over a biofilm, a three-dimensional (3-D) community of microorganisms immobilized at a substratum, were made using an acoustic microscope operating at frequencies up to 70 MHz. The microscope scanned a 2.5-mm by 2.5-mm region of a living biofilm having a nominal thickness of 100 microm. Spatial variation of surface heterogeneity, thickness, interior structure, and biomass were estimated. Thickness was estimated as the product of the speed of sound of the medium and the interim between the highest signal peak and that of the substratum plane without biofilm. The thickest portions of biofilm were 145 microm; however, slender structures attributed as streamers extended above, with one obtaining a 274-microm height above the substratum. Three-dimensional iso-contours of amplitude were used to estimate the internal structure of the biofilm. Backscatter amplitude was examined at five zones of increasing height from the substratum to examine biomass distribution. Ultrasound-based estimates of thickness were corroborated with optical microscopy. The experimental acoustic and optical systems, methods used to estimate biofilm properties, and potential applications for the resulting data are discussed.

Ultrasonic attenuation values of metals deduced using conventional pulse/echo methods contain contributions from both grain scattering and energy absorption (arising from internal friction). In contrast, the energy loss mechanisms, which contribute to diffuse field measurements, are believed to be insensitive to scattering, and hence provide information on internal friction only. In this work several metal specimens are studied, some of which have attenuation values in good agreement with the predictions of grain‐scattering models, and others which do not. The diffuse field decay rate of each specimen is measured, and used to deduce Q inverse, which is a measure of the internal friction in a material. The comparison of the attenuation and diffuse field measurements indicate that specimens in which the measured and predicted values of attenuation were not in good agreement have a significant internal friction contribution towards attenuation, indicating that absorption and not grain scattering is the dominant attenuation mechanism.

This document summarizes the activities performed and progress made in FY-03. Various approaches for automating the particle fuel production QC process using on-line nondestructive methods for higher reliability were evaluated. In this first-year of a three-year project, surrogate fuel particles made available for testing included leftovers from initial coater development runs. These particles had a high defect fraction and the particle properties spanned a wide range, providing the opportunity to examine worst-case conditions before refining the inspection methods to detect more subtle coating features. Particles specifically designed to evaluate the NDE methods being investigated under this project will be specified and fabricated at ORNL early next reporting period. The literature was reviewed for existing inspection technology and to identify many of the fuel particle conditions thought to degrade its performance. A modeling study, including the electromagnetic and techniques, showed that the in-line electromagnetic methods should provide measurable responses to missing layers, kernel diameter, and changes in coating layer thickness, with reasonable assumptions made for material conductivities. The modeling study for the ultrasonic methods provided the resonant frequencies that should be measured using the resonant ultrasound technique, and the results from these calculations were published in the proceedings for two conferences. more » The notion of a particle quality index to relate coating properties to fabrication process parameters was explored. Progress was made in understanding the fabrication process. GA identified key literature in this area and Saurwein (2003a) provided a literature review/summary. This literature has been reviewed. An approach previously applied to flexible manufacturing was adopted and the modification and development of the concepts to meet TRISO particle fuel manufacturing and QA/QC needs initiated. This approach establishes relationships between key process parameters and part parameters, including ''defects'' for each manufacturing step--which in this case is a coating layer. This activity will continue in year two, when an initial evaluation will be made using available process and particle data. Radiographic and Computed Tomography (CT) techniques were developed and refined to examine individual particles and batches of up to about 30 to 40 particles for kernel diameter, coating layer thickness and spatial uniformity. These results are essential for developing the defect library of characterized particles that will be used to calibrate the high-speed nondestructive measurement methods that are found capable of automatically detecting particles having properties outside a specified range. The in-line inspection methods evaluated include the electrical property measurement methods traditionally referred to as eddy current and capacitance (or dielectric) in the nondestructive test methods literature. An eddy current technique was developed and evaluated on stationary particles. Good correlation was found between the eddy current measurements and the radiographically determined particle dimensions. Initial measurements on fuel compacts using the eddy current approach showed that these materials are amenable to electrical inspection and that significant coil impedance variability can be observed among different samples. « less

The efficient calculation of the resonance frequencies is required for the effective application of resonant ultrasound spectroscopy (RUS) to determine the relevant properties of an elastic object. If a suitable number of the resonance frequencies of an elastic object are known, in principle, one can deduce a number of its physical properties like elastic constants, density, dimensions, shape, etc. However, general analytic expressions are not available for the normal mode free vibrations of a body with arbitrary shape and elastic properties. It was noticed by Holland and Demarest (1971) that a simple variational principle can be applied to compute the normal mode frequencies of an elastic body with free boundaries. Based on this variational method, Visscher et al. (1991) developed the XYZ algorithm which can be applied to compute the resonance frequencies of a body with arbitrary shape and elastic properties. Since layered systems are finding increasing use in engineering applications, computational stud...

It is known that high energy radiation can have numerous effects on materials. In metals and alloys, the effects include, but may not be limited to, mechanical property changes, physical property changes, compositional changes, phase changes, and dimensional changes. Metals and alloys which undergo high energy self-irradiation are also susceptible to these changes. One of the greatest concerns with irradiation of materials is the phenomenon of void swelling which has been observed in a wide variety of metals and alloys. Irradiation causes the formation of a high concentration point defects and microclusters of vacancies and interstitials. With the assistance of an inert atom such as helium, the vacancy-type defects can coalesce to form a stable bubble. This bubble will continue to grow through the net absorption of more vacancy-type defects and helium atoms, and upon reaching a certain critical size, the bubble will begin to grow at an accelerated rate without the assistance of inert atom absorption. The bubble is then said to be an unstably growing void. Depending on the alloy system and environment, swelling values can reach in excess of 50% !V/Vo where Vo is the initial volume of the material. Along with dimensional changes resulting from themore » formation of bubbles and voids comes changes in the macroscopically observed speed of sound, moduli, electrical resistivity, yield strength, and other properties. These effects can be detrimental to the designed operation of the aged components. In situations where irradiation has sufficient time to cause degradation to materials used in critical applications such as nuclear reactor core structural materials, it is advisable to regularly survey the material properties. It is common practice to use surveillance specimens, but this is not always possible. When surveillance materials are not available, other means for surveying the material properties must be utilized. Sometimes it is possible to core out a small sample which may be used for material properties measurements. A more appealing solution is to use nondestructive evaluation (NDE) methods.« less

There is a desire to characterize plastically deformed regions in structures to monitor their integrity. Of particular importance is the accurate prediction of the lifetime of damaged pipelines due to outside force. In order to accurately predict the remaining life it is essential to accurately determine the degree stress and strain in the damaged region for input into fracture mechanics models. Currently, determination of the degree of stress and strain in damaged regions utilizing ultrasonic velocity measurements is complicated by the inherent texture in the materials and the difficulty in separating these effects from the stress and strain contributions. We will report ultrasonic velocity measurements on plastically deformed steel specimens to elucidate the state of damage. Specifically, we have found the shear wave birefringence and SH wave velocity are sensitive to the degree of plastic deformation. Ultrasonic results will be compared with finite element modeling calculation of the stress and strain ...

An ultrasonic wave propagating through a microscopically inhomogeneous medium, such as polycrystalline materials, is subject to scattering at the grain boundaries. The fraction of energy removed from the incident wave is responsible for important phenomenon like attenuation, dispersion, and background “noise” associated with a given ultrasonic inspection system. Since the backscattered signals tend to mask the signals from small and subtle defects, the estimation of probability of detection of such defects requires the quantitative description of these signals. Although considerable attention has been given to the understanding of mean propagation characteristics of an ultrasonic beam, until recently there have been relatively little efforts devoted towards rigorous treatments of backscattered signals. In this research, we attempt to include some degree of multiple scattering in the calculation of the backscattered signals by developing a formalism that relates mean wave propagation characteristics to the...

Reliable nondestructive evaluation of structural/machine components fabricated from polycrystalline materials require the knowledge of attenuation and dispersion of an ultrasonic wave propagating through such microscopically inhomogeneous medium. Expected propagation characteristics of ultrasonic waves in randomly oriented equiaxed grains are relatively well understood. But when the grains are elongated and/or preferentially oriented, the wave propagation constants exhibit anisotropic behavior. The authors have published a number of research articles on propagation of ultrasonic waves in materials with macroscopic texture and elongated grains. The present paper sheds more light on the effect of grain shape on the attenuation and dispersion of ultrasonic waves in polycrystals. Specifically, theoretical results are presented showing the effects of different grain aspect ratios. It is observed that for the same effective grain volume, grain elongation has smaller effect on attenuation.