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Cephalopods are important prey in the diet of top predators, such as marine mammals and seabirds. However, detailed information on their trophic relationships in the Patagonian marine ecosystem is scarce, including those cephalopod species with commercial interest. The aims of this study were to evaluate the composition of the cephalopod component in the diet of Otaria byronia and determine the habitat use and trophic levels of their main cephalopod prey by measuring the stable isotopic signature of cephalopod beaks. Between May 2005 and February 2009, fresh faecal samples were collected from two sea lions rookeries in San Matias Gulf. Cephalopods occurred in 39.4% of the 1112 samples collected during the whole period of study. The dominant prey species was Octopus tehuelchus, which occurred in 45.8% of scats containing cephalopod remains, and represented 58.7% in terms of numerical abundance and 52.0% in mass of cephalopods consumed. The second species most consumed was the myopsid Doryteuthis gahi. The significant higher δ15N values of O. tehuelchus beaks in comparison with those of D. gahi showed that these two species have different trophic levels while occupying similar habitat (δ13C values) in neritic waters of the Patagonian shelf.
Spectra at 16 - 45 μm of several regions within the central 80″ of the Galaxy have been obtained at 20″ resolution using the Goddard Cryogenic Grating Spectrometer No. 2 on the Kuiper Airborne Observatory. A broad band of excess emission extending from 24 to 45 μm is present in the spectra at positions covering the “tongue” and the inner edge of the circumnuclear disk. A similar dust emission feature has been observed in some carbon-rich evolved stars and in a nitrogen-rich evolved massive star. The observations reported here are the first detection of this dust emission feature in the interstellar medium. After considering several possible candidates of the carrier for this 30 μm dust feature, we find that MgS is the best owing to its good fit to the observed spectra. The origin of this ~ 30 μm feature in the Galactic center is unknown. Based on the theoretical results of dust condensation and elemental abundances in a supernova, we find that the supernovae in the central 500 pc could provide the amount of MgS dust, which we proposed as the carrier of the 30 μm dust feature, observed in the central 3 pc.
We have assembled a new sample of some of the most FIR-luminous galaxies in the Universe and have imaged them in 1.1 mm dust emission and measured their redshifts 1 < z < 4 via CO emission lines using the 32-m Large Millimeter Telescope / Gran Telescopio Milimétrico (LMT/GTM). Our sample of 31 submm galaxies (SMGs), culled from the Planck and Herschel all-sky surveys, includes 14 of the 21 most luminous galaxies known, with LFIR > 1014L⊙ and SFR > 104M⊙/yr. These extreme inferred luminosities – and multiple / extended 1.1 mm images – imply that most or all are strongly gravitationally lensed, with typical magnification μ ~ 10 × . The gravitational lensing provides two significant benefits: (1) it boosts the S/N, and (2) it allows investigation of star formation and gas processes on sub-kpc scales.
Due to its favourable properties, in particular, low permeability and swelling capacity, bentonite has been favoured as an engineered-barrier and backfill material for the geological storage of radioactive waste. To ensure its safe long-term performance it is important to understand any changes in these properties when the material is subject to heat-emitting waste. As such, this study investigates the hydraulic response of bentonite under multi-step thermal loading subject to a constant-volume boundary condition, to represent a barrier system used in a crystalline or other hard-rock host rock. The experimental set up allows continuous measurement of the hydraulic and mechanical responses during each phase of the thermal cycle. After the initial hydration of the bentonite, the temperature was raised in 20°C increments from 20 to 80°C followed by a final step to reach 120°C. Each temperature was held constant for at least 7–10 days to allow the hydraulic transients to equilibrate. The data suggest that the permeability of bentonite appears to be sensitive to changes in temperature which may extend beyond those explained by simple changes in water viscosity. However, permeability may be boundary-condition dependent and this should be considered when designing experiments or applying these results to other repository host rocks. Either way, the magnitude of the change in permeability observed in this study is minor and its impact on the hydraulic performance of the barrier is negligible.
One of the most challenging aspects of understanding the flow of gas and water during testing in clay-rich low-permeability materials is the difficulty in visualizing localized flow. Whilst understanding has been increased using X-ray Computed-tomography (CT) scanning, synchrotron X-ray imaging and Nuclear Magnetic Resonance (NMR) imaging, real-time testing is problematic under realistic in situ conditions confining pressures, which require steel pressure vessels. These methods tend not to have the nano-metre scale resolution necessary for clay mineral visualization, and are generally not compatible with the long duration necessary to investigate flow in such materials. Therefore other methods are necessary to visualize flow paths during post-mortem analysis of test samples. Several methodologies have been established at the British Geological Survey (BGS), in order to visualize flow paths both directly and indirectly. These include: (1) the injection of fluorescein-stained water or deuterium oxide; (2) the introduction of nanoparticles that are transported by carrier gas; (3) the use of radiologically tagged gas; and (4) the development of apparatus for the direct visualization of clay. These methodologies have greatly increased our understanding of the transport of water and gas through intact and fractured clay-rich materials. The body of evidence for gas transport through the formation of dilatant pathways is now considerable. This study presents observations using a new apparatus to directly visualize the flow of gas in a kaolinite paste. The results presented provide an insight into the flow of gas in clay-rich rocks. The flow of gas through dilatant pathways has been shown in a number of argillaceous materials (Angeli et al., 2009; Autio et al., 2006; Cuss et al., 2014; Harrington et al., 2012). These pathways are pressure induced and an increase in gas pressure leads to the dilation of pathways. Once the gas breakthrough occurs, pressure decreases and pathways begin to close. This new approach is providing a unique insight into the complex processes involved during the onset, development and closure of these dilatant gas pathways.
We describe two cases of infant botulism due to Clostridium butyricum producing botulinum type E neurotoxin (BoNT/E) and a previously unreported environmental source. The infants presented at age 11 days with poor feeding and lethargy, hypotonia, dilated pupils and absent reflexes. Faecal samples were positive for C. butyricum BoNT/E. The infants recovered after treatment including botulism immune globulin intravenous (BIG-IV). C. butyricum BoNT/E was isolated from water from tanks housing pet ‘yellow-bellied’ terrapins (Trachemys scripta scripta): in case A the terrapins were in the infant's home; in case B a relative fed the terrapin prior to holding and feeding the infant when both visited another relative. C. butyricum isolates from the infants and the respective terrapin tank waters were indistinguishable by molecular typing. Review of a case of C. butyricum BoNT/E botulism in the UK found that there was a pet terrapin where the infant was living. It is concluded that the C. butyricum-producing BoNT type E in these cases of infant botulism most likely originated from pet terrapins. These findings reinforce public health advice that reptiles, including terrapins, are not suitable pets for children aged <5 years, and highlight the importance of hand washing after handling these pets.
The concept of effective stress is one of the basic tenets of rock mechanics where the stress acting on a rock can be viewed as the total stress minus the pore water pressure. In many materials, including clay-rich rocks, this relationship has been seen to be imperfect and a coefficient (χ) is added to account for the mechanical properties of the clay matrix. Recent experimental results during the flow testing (both gas and water) of several rocks (Callovo-Oxfordian claystone, Opalinus Clay, Boom Clay) and geomaterials (bentonite, kaolinite) has given evidence for stable high pressure differentials. The design of the experiments allows multiple measurements of pore pressure, which commonly shows a complex distribution for several different experimental geometries. The observed stable high pressure differentials and heterogeneous pore pressure distribution makes the describing of stress states in terms of effective stress complex. Highly localized pore pressures can be sustained by argillaceous materials and concepts of evenly distributed pore pressures throughout the sample (i.e. conventional effective stress) do not fit many clay-rich rocks if the complexities observed on the micro-scale are not incorporated, especially when considering the case of gas flow.
A new data analysis toolkit which is suitable for the analysis of large-scale, long-term datasets and the phenomenon/anomalies they represent is described. The toolkit aims to expose and quantify scientific information in a number of forms contained within a time-series based dataset in a quantitative and rigorous manner, reducing the subjectivity of observations made, thereby supporting the scientific observer. The features contained within the toolkit include the ability to handle non-uniform datasets, time-series component determination, frequency component determination, feature/event detection and characterization/parameterization of local behaviours. An application is presented of a case study dataset arising from the 'Lasgit' experiment.
Understanding flow along fractures and faults is of importance to the performance assessment (PA) of a geological disposal facility (GDF) for radioactive waste. Flow can occur along pre-existing fractures in the host-rock or along fractures created during the construction of the GDF within the excavation damage zone (EDZ). The complex fracture network will have a range of orientations and will exist within a complex stress regime. Critical stress theory suggests that fractures close to localized shear failure are critically stressed and therefore most conductive to fluid flow. Analysis of fault geometry and stress conditions at Sellafield has revealed that no features were found to be, or even close to being, classified as critically stressed, despite some being conductive. In order to understand the underlying reasons why non-critically stressed fractures were conductive a series of laboratory experiments were performed. A bespoke angled shear rig (ASR) was built in order to study the relationship between fluid flow (water and gas) through a fracture surface as a function of normal load. Fluid flow reduced with an increase in normal load, as expected. During unloading considerable hysteresis was seen in flow and shear stress. Fracture flow was only partially recovered for water injection, whereas gas flow increased remarkably during unloading. The ratio of shear stress to normal stress seems to control the fluid flow properties during the unloading stage of the experiment demonstrating its significance in fracture flow. The exhumation of the Sellafield area during the Palaeogene–Neogene resulted in considerable stress relaxation and in fractures becoming non-critically stressed. The hysteresis in shear stress during uplift has resulted in faults remaining, or becoming, conductive. The field and laboratory observations illustrate that understanding the stress-history of a fractured rock mass is essential, and a mere understanding of the current stress regime is insufficient to estimate the flow characteristics of present-day fractures.
To understand the fate and impact of gas produced within a repository for radioactive waste, a series of laboratory and field scale experiments have been performed on the Callovo-Oxfordian claystone (COx), the proposed host rock for the French repository. Results show the movement of gas is through a localized network of pathways, whose properties vary temporarily and spatially within the claystone. Significant evidence exists from detailed laboratory studies for the movement of gas along highly unstable pathways, whose aperture and geometry vary as a function of local stress, gas and porewater pressures. The coupling of these parameters results in the development of significant time-dependent effects, impacting on all aspects of COx behaviour, from gas breakthrough time, to the control of deformation processes. Variations in gas entry, breakthrough and steady-state pressures are indicative of microstructural heterogeneity which exerts an important control on the movement of gas. The localization of gas flow is also evident in preliminary results from the large scale gas injection test (PGZ) where gas flow is initially focussed within the excavation damaged zone (EDZ), which acts as a preferential pathway for gas. Numerical models based on conventional two-phase flow theory are unable to adequately describe the detailed observations from laboratory tests.
Corrosion, water radiolysis and microbial degradation will result in the generation of gas within repositories designed for the geological disposal of high-level radioactive waste. It is therefore crucial in the design of such facilities that the relevant mechanisms allowing gas migration through repository materials, both engineered barriers and clay-based candidate host rocks, are correctly identified. In Belgium, the Boom Clay represents a candidate host material for which the advective gas breakthrough characteristics and transport properties have been extensively tested and are well defined by numerous studies. The Boom Clay displays a significant capacity for self-sealing and both laboratory and field tests indicate that advective gas transport occurs not by visco-capillary flow, but instead through the formation of pressure-induced dilatant pathways. In this study, we present results from a gas injection test designed to demonstrate the presence of these features by injecting nanoparticulate tracers with helium gas into a sample of Boom Clay. The results provide conclusive evidence for the formation of transient, dilatant gas pathways within a candidate clay-based host rock. This technique provides a novel diagnostic tool for the identification of processes governing multi-phase flow, supporting robust long-term assessments of repository performance.
In the Swedish KBS-3 repository concept, there is potential for gas to be generated from corrosion of ferrous materials under anoxic conditions, combined with the radioactive decay of the waste and radiolysis of water. A full understanding of the probable behaviour of this gas phase within the engineered barrier system (EBS) is therefore required for performance assessment. We demonstrate key features from gas transport experiments on pre-compacted Mx80 bentonite, under laboratory and field conditions, and discuss their implications in terms of a conceptual model for gas migration behaviour. On both scales, major gas entry is seen to occur close to the sum of the porewater and swelling pressures of the bentonite. In addition, gas pressure at breakthrough is profoundly sensitive to the number and location of available sinks for gas escape. Observations of breakthrough can be explained by the creation of dilatational pathways, resulting in localized changes in the monitored porewater pressures and total stresses. These pathways are highly unstable, evolving spatially and temporally, and must consequently influence the gas permeability as their distribution/geometry develops.
Such observations are poorly embodied by conventional concepts of two-phase flow, which do not fully represent the key processes involved. Although dilatancy based models provide a better description of these processes, the paucity of data limits further development and validation of these models at present.
Controlled flow-rate gas injection experiments have been performed on
pre-compacted samples of KBS-3 specification M×801 buffer
bentonite using helium as a safe replacement for hydrogen. By simultaneously
applying a confining pressure and backpressure, specimens were
isotropically-consolidated and fully water-saturated under pre-determined
effective stress conditions, before injecting gas using a syringe pump.
Ingoing and outgoing gas fluxes were monitored. All tests exhibited a
conspicuous threshold pressure for breakthrough, somewhat larger than the
sum of the swelling pressure and the backpressure. All tests showed a
post-peak negative transient leading to steady-state gas flow. Using a
stepped history of flow rate, the flow law was shown to be nonlinear. With
the injection pump stationary (i.e. zero applied flow rate), gas pressure
declined with time to a finite value. When gas flow was reestablished, the
threshold value for gas breakthrough was found to be significantly lower
than in virgin clay. There is strong evidence to suggest that the capillary
pressure for the penetration of interparticle pore space of buffer bentonite
is of such a magnitude that normal two-phase flow is impossible. Gas entry
and breakthrough is therefore accompanied by the development of microcracks
which propagate through the clay from gas source to sink. The experiments
suggest that these pathways open under high gas pressure conditions and
partially close if gas pressure falls, providing a possible explanation of
the nonlinearity of the flow law.
Thin coatings of Al2O3, and Y2O3, have been prepared on desized Nicalon yarn. The layers were deposited by dip coating in homogeneous, alcohol solutions of partially hydrolyzed metal alkoxides. The coating thicknesses could be controlled by multiple dipping.
The uniformity of the coatings was affected by the alkoxide concentration. Solutions containing greater than 1 wt % equivalent oxide resulted in oxide bridging the void between the fibers.
Transmission Electron Microscopy (TEM) studies on alumina coatings formed by dip coating 300 mesh nickel grids, have shown that either eta or gamma alumina is formed after heating at temperatures as low as 700 °C. The rate of grain growth increases as the temperature increases. In addition, increased grain growth is observed for films produced from solutions with higher water:metal ratios.
The strength of coated fibers heat treated in air after coating has been determined. Alumina, and yttria coatings reduce the strength of the fiber after heating at temperatures above 900 °C. Scanning Auger analysis suggests that the coating is reacting with the fiber at these high temperatures.
A precipitation process has been developed to prepare precursor powders which can be calcined and sintered to form high critical temperature superconductors such as YBa2Cu3O7−x. Precursor powders are prepared using a continuous precipitation system in which a solution containing highly soluble salts of the desired metal cations is rapidly and completely mixed with a solution containing precipitating anions such as hydroxide and carbonate ions. The resulting amorphous powder can be calcined to form sub-micron particles of desired superconducting phases which are useful in preparing inks for the ink-jet printing of superconducting interconnects. The powders can be redissolved in organic solvents to form solutions which can be used in spin or dip coating substrates with thin superconducting films. Finally, the powders have been used to prepare bulk ceramics which exhibit the highest reported critical currents of any chem-prep ceramics. Bulk samples prepared from chloride doped precursors exhibit large, oriented grains and extensive flux pinning.
Owing to modern lifestyles, individuals are dependent on out-of-home eating. The catering sector can have a pivotal role in influencing our food choices. The objective of the present study was to examine the impact of a structured catering initiative on food choices in a public sector workplace setting.
A cross-sectional comparison study in two hospitals, one of which had implemented a catering initiative designed to provide nutritious food while reducing sugar, fat and salt intakes.
Two public sector hospitals in Cork, Ireland.
A total of 100 random participants aged 18–64 years (fifty intervention, fifty non-intervention) who consumed at least one main meal in the hospital staff canteen daily. Each respondent was asked to complete one anonymous 24 h dietary recall and questionnaire. Food and nutrient analysis was conducted using WISP (Weighed Intake Software Program).
Reported mean intakes of total sugars (P < 0·001), total fat (P < 0·000), saturated fat (P < 0·000) and salt (P < 0·046) were significantly lower in the intervention hospital when adjusted for age and gender. In the intervention hospital, 72 % of respondents, compared with 42 % in the non-intervention hospital, complied with the recommended under-3 daily servings of food high in fat and sugar (P < 0·005). In the intervention hospital, 43 % of respondents exceeded the recommended salt intake of 4–6 g/d, compared with 57 % in the non-intervention hospital.
Structured catering initiatives in the workplace are a potentially important option in the promotion of healthy food choices. Targeted public health programmes and health policy changes are needed to motivate caterers in the public sector and other industries to develop interventions that promote a healthy diet.
Small mammals were trapped in four rain forest fragments (3, 8, 20 and 97 ha), in an agricultural
landscape, and in comparable continuous tropical rain forest in north Queensland, Australia over 2 y. The most
frequently captured species were four murid rodents. Melomys cervinipes were captured in similar numbers in both
continuous and fragmented forest. This species achieves greatest abundance at forest edges and this study suggests
that edges of fragments and edges of continuous forest will support similar densities. Abundance of Uromys
caudimaculatus was positively correlated with size of fragment and peaked in continuous forest. This species had a home range
larger than the smaller fragments and was thus disadvantaged but its ability to utilize the agricultural matrix between
fragments mitigated the effect. Rattus leucopus and R. fuscipes were most abundant in fragments and continuous forest
respectively but both species occurred in similar abundance in the 97-ha fragment. This suggests their population size
is related to habitat rather than competitive exclusion as previously postulated. Ordination of the populations of the
nine most commonly captured mammals, separated the fragment and continuous sites but placed the largest fragment
closest to the continuous sites. The contrasting response of the two Rattus spp. was the primary influence on the
ordination. Second in importance was Trichosurus vulpecula, a folivorous possum, which was absent from the
continuous sites. The fragments may have had more nutrient-rich, pioneer tree foliage than continuous forest. Isoodon
macrourus, Perameles nasuta, Antechinus godmani and Uromys hadrourus also showed positive or negative response to
fragmentation. Species utilizing the matrix between forest fragments and species adapted to forest edge are advantaged
by the fragmentation process whereas forest specialists tend to extinction in fragments, particularly where the home
range of the animal is not many times smaller than the fragment.