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The efficiency of grass nitrogen utilisation for milk production tends to be low, due partly to the slow rate of release of energy in the rumen which reduces the efficiency of capture of rapidly degradable plant proteins by the rumen microbial population. When additional sugars are infused into the rumen, microbial protein production is increased (Rooke et al., 1987). The objective of this study was to assess milk production using a grass variety that has been bred to express elevated water soluble carbohydrate (WSC) concentrations.
Eight multiparous Holstein-Friesian dairy cows in mid lactation (176 days ± s.e. 3.6) were used in a continuous design, zero-grazing experiment. Following covariate measurements taken from all animals on a standard grazing diet, four animals were each offered one of two varieties of perennial ryegrass at ad libitum rate: AberDove, bred to express high WSC concentrations; and AberElan, a commercially available variety, used as a control.
Observations from basal water-pressure sensors along the length of Bench Glacier, Alaska, USA, show that diurnal fluctuations of water pressure are seasonal and restricted to summer. Most notable about these fluctuations is their disappearance in the late summer and early autumn, long before the seasonal end of diurnal meltwater input. Here we present data documenting the end of diurnal water-pressure fluctuations during the 2002 and 2003 melt seasons. The end of diurnal fluctuations occurred abruptly in multiple boreholes spaced meters to kilometers apart. There was no obvious spatial progression of termination events, and a clear correlation with meteorological forcing or discharge in the outlet stream was not apparent. After diurnal pressure fluctuations ended, basal water pressure returned to a high, generally steady, value either in an irregular pattern or by a distinct increase. This high water pressure was interrupted by episodic, acyclic events throughout the autumn before becoming stable and high in winter.
An experimental program at Worthington Glacier, Alaska, U.S.A., has yielded the first in situ measurement of the full stress tensor in glacier ice. Measurements were made with an array of stiff (low-compliance) normal-force sensors frozen into a borehole at 120 m depth. Freezing in temperate ice was accomplished by a down-hole heat exchanger which extracted heat at a rate of 15 W. Under slowly varying stress conditions, relaxation of stress anomalies by viscous creep following drilling of the hole and installation of the sensors allows for equilibration of measured stresses with far-field stresses. Equilibration of local and far-field stresses was confirmed and pressure sensors calibrated in laboratory experiments prior to the field program. Results of the stress measurements show principal axes of the stress tensor oriented in directions consistent with the geometry of the glacier and broadly consistent with measured englacial strain rate. The magnitudes of stress-tensor components are more error-prone and more sensitive to uncertainty in sensor magnitude than uncertainty in sensor orientation. Mean stress determined by pressure measurements agrees with estimated lithostatic overburden to within approximately 15%. Unexpected results include a stress perturbation lasting about 5 days that caused a rotation of the orientations of the principal stress axes of approximately 5° about an axis pointing in the down-flow direction.
To evaluate the efficacy of a multijet cold-plasma system and its efficacy in decontaminating 2 surfaces commonly found in hospitals
An in vitro study of common causes of healthcare-acquired infection
Log10 9 cultures of methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended spectrum β-lactamase–producing Escherichia coli, and Acinetobacter baumannii were applied to 5-cm2 sections of stainless steel and mattress. Human serum albumin (HSA) was used as a proxy marker for organic material, and atomic force microscopy (AFM) was used to study the impact on bacterial cell structure. The inoculated surfaces were exposed to a cold-air-plasma–generating multijet prototype for 15, 20, 30, and 45 seconds.
After 45 seconds, at least 3 to 4 log reductions were achieved for all bacteria on the mattress, while 3 to 6 log reductions were observed on stainless steel. The presence of HSA had no appreciable effect on bacterial eradication. The surfaces with bacteria exposed to AFM showed significant morphological changes indicative of “etching” due to the action of highly charged ions produced by the plasma.
This multijet cold-plasma prototype has the potential to augment current environmental decontamination approaches but needs further evaluation in a clinical setting to confirm its effectiveness.
Plasmodium knowlesi has risen in importance as a zoonotic parasite that has been causing regular episodes of malaria throughout South East Asia. The P. knowlesi genome sequence generated in 2008 highlighted and confirmed many similarities and differences in Plasmodium species, including a global view of several multigene families, such as the large SICAvar multigene family encoding the variant antigens known as the schizont-infected cell agglutination proteins. However, repetitive DNA sequences are the bane of any genome project, and this and other Plasmodium genome projects have not been immune to the gaps, rearrangements and other pitfalls created by these genomic features. Today, long-read PacBio and chromatin conformation technologies are overcoming such obstacles. Here, based on the use of these technologies, we present a highly refined de novo P. knowlesi genome sequence of the Pk1(A+) clone. This sequence and annotation, referred to as the ‘MaHPIC Pk genome sequence’, includes manual annotation of the SICAvar gene family with 136 full-length members categorized as type I or II. This sequence provides a framework that will permit a better understanding of the SICAvar repertoire, selective pressures acting on this gene family and mechanisms of antigenic variation in this species and other pathogens.
Values of the strain-rate tensor represented at a 20 m length scale are found to explain the pattern and orientation of crevasses in a 0.13 km2 reach of Worthington Glacier, Alaska, U.S.A. The flow field of the reach is constructed from surveyed displacements of 110 markers spaced 20-30 m apart. A velocity gradient method is then used to calculate values of the principal strain-rate axes at the nodes of a 20 m x 20 m orthogonal grid. Crevasses in the study reach are of two types, splaying and transverse, and are everywhere normal to the trajectories of greatest (most tensile) principal strain rate. Splaying crevasses exist where the longitudinal strain rate (
x) is ≤ 0 and transverse crevasses are present under longitudinally extending flow (i.e.
x > 0). The orientation of crevasses changes in the down-glacier direction, but the calculated rotation by the flow field does not account for this change in orientation. Observations suggest that individual crevasses represent local values of the regional flow field and are transient on the time-scale of 1-2 years; they are not persistent features that are translated and rotated by flow. Crevasse patterns are thus found to be a useful tool for mapping the strain-rate tensor in this reach of a temperate valley glacier.
We describe the performance of the Boolardy Engineering Test Array, the prototype for the Australian Square Kilometre Array Pathfinder telescope. Boolardy Engineering Test Array is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarisation beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of Boolardy Engineering Test Array’s performance: sensitivity, beam characteristics, polarimetric properties, and image quality. We summarise the astronomical science that it has produced and draw lessons from operating Boolardy Engineering Test Array that will be relevant to the commissioning and operation of the final Australian Square Kilometre Array Path telescope.
Campylobacter is the leading cause of bacterial diarrhoeal disease worldwide, with raw and undercooked poultry meat and products the primary source of infection. Colonization of broiler chicken flocks with Campylobacter has proved difficult to prevent, even with high levels of biosecurity. Dipteran flies are proven carriers of Campylobacter and their ingress into broiler houses may contribute to its transmission to broiler chickens. However, this has not been investigated in the UK. Campylobacter was cultured from 2195 flies collected from four UK broiler farms. Of flies cultured individually, 0·22% [2/902, 95% confidence interval (CI) 0–0·53] were positive by culture for Campylobacter spp. Additionally, 1293 flies were grouped by family and cultured in 127 batches: 4/127 (3·15%, 95% CI 0·11-6·19) from three broiler farms were positive for Campylobacter. Multilocus sequence typing of isolates demonstrated that the flies were carrying broiler-associated sequence types, responsible for human enteric illness. Malaise traps were used to survey the dipteran species diversity on study farms and also revealed up to 612 flies present around broiler-house ventilation inlets over a 2-h period. Therefore, despite the low prevalence of Campylobacter cultured from flies, the risk of transmission by this route may be high, particularly during summer when fly populations are greatest.
The Harwell system for measuring milligram size samples using Brookhaven miniature gas counters is fully operative. It comprises 12 counters of different sizes which operate simultaneously within a single NaI crystal (300mm diameter × 300mm long) acting as an anti-coincidence guard counter. Brief details are given of the construction and commissioning of the system, including counter assembly, shield design, electronics, data capture, data analysis, and chemical processing and filling procedures. The performance of the system and an overall view of the fields of application for which the counters have important applications are discussed.
A suite of surface and basal measurements during and after borehole drilling is used to perform in situ investigation of the local basal drainage system and pressure forcing in western Greenland. Drill and borehole water temperature were monitored during borehole drilling, which was performed with dyed hot water. After drilling, borehole water pressure and basal dye concentration were measured concurrently with positions in a GPS strain diamond at the surface. Water pressure exhibited diurnal changes in antiphase with velocity. Dye monitoring in the borehole revealed stagnant basal water for nearly 2 weeks. The interpretation of initial connection to an isolated basal cavity is corroborated by the thermal signature of borehole water during hot water drilling. Measurement-based estimates of cavity size are on the order of cubic meters, and analysis indicates that small changes in its volume could induce the observed pressure variations. It is found that longitudinal coupling effects are unable to force necessary volume changes at the site. Sliding-driven basal cavity opening and elastic uplift from load transfer are plausible mechanisms controlling pressure variations. Elastic uplift requires forcing from a hydraulically connected reach, which observations suggest must be relatively small and in close proximity to the isolated cavity.
Epidemiological studies have identified increased colorectal cancer (CRC) risk with high red meat (HRM) intakes, whereas dietary fibre intake appears to be protective. In the present study, we examined whether a HRM diet increased rectal O6-methyl-2-deoxyguanosine (O6MeG) adduct levels in healthy human subjects, and whether butyrylated high-amylose maize starch (HAMSB) was protective. A group of twenty-three individuals consumed 300 g/d of cooked red meat without (HRM diet) or with 40 g/d of HAMSB (HRM+HAMSB diet) over 4-week periods separated by a 4-week washout in a randomised cross-over design. Stool and rectal biopsy samples were collected for biochemical, microbial and immunohistochemical analyses at baseline and at the end of each 4-week intervention period. The HRM diet increased rectal O6MeG adducts relative to its baseline by 21 % (P< 0·01), whereas the addition of HAMSB to the HRM diet prevented this increase. Epithelial proliferation increased with both the HRM (P< 0·001) and HRM+HAMSB (P< 0·05) diets when compared with their respective baseline levels, but was lower following the HRM+HAMSB diet compared with the HRM diet (P< 0·05). Relative to its baseline, the HRM+HAMSB diet increased the excretion of SCFA by over 20 % (P< 0·05) and increased the absolute abundances of the Clostridium coccoides group (P< 0·05), the Clostridiumleptum group (P< 0·05), Lactobacillus spp. (P< 0·01), Parabacteroides distasonis (P< 0·001) and Ruminococcus bromii (P< 0·05), but lowered Ruminococcus torques (P< 0·05) and the proportions of Ruminococcus gnavus, Ruminococcus torques and Escherichia coli (P< 0·01). HRM consumption could increase the risk of CRC through increased formation of colorectal epithelial O6MeG adducts. HAMSB consumption prevented red meat-induced adduct formation, which may be associated with increased stool SCFA levels and/or changes in the microbiota composition.
This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.
Films of GaN have been grown using a modified MBE method in which the active nitrogen is supplied from an RF activated plasma source. Wurtzite films grown on (0 0 1) oriented GaAs substrates show highly defective, ordered polycrystalline growth with a columnar structure; the (0 0 0 1) planes of the layers being parallel to the (0 0 1) planes of the GaAs substrate. Films grown using a coincident As flux, however, have a single crystal zinc-blende growth mode. They have better structural and optical properties. To improve the properties of the wurtzite films we have studied the growth of such films on (1 1 1)A and (1 1 1)B oriented GaAs substrates. The improved structural properties of such films, assessed using x-ray and TEM methods, correlate with better low temperature PL performance.
Enrichment culture is often used to isolate Campylobacter. This study compared isolation of Campylobacter spp. from 119 broiler chicken environments from two farms, using Preston and modified Exeter (mExeter) and modified Bolton (mBolton) enrichments. mExeter was significantly more effective in isolating Campylobacter spp. from the environmental samples compared to Preston (P<0·001) and mBolton (P<0·04) broths but there was no significant difference between the latter two methods (P>0·05). Enrichment broth type did not affect isolation from chicken faecal or soil and litter samples. C. jejuni was isolated from significantly more environmental samples using mExeter broth compared to Preston (P<0·01) and mBolton (P<0·003) broths; there was no difference between the latter two methods or between all methods for detection of C. coli (P>0·05). Only C. coli was isolated from the soil and litter samples and although both C. jejuni and C. coli were recovered from the faecal samples there was no effect of using different enrichment broths. The majority of samples where the same species had been isolated yielded the same or closely related genotypes as defined by pulsed-field gel electrophoresis. Isolates recovered using Preston and mBolton broths were less genetically diverse than those from mExeter broth. We conclude that the enrichment method used affects both the number and species of Campylobacter isolated from naturally contaminated samples.
Epitaxial TiSi2 films have been grown by molecular beam epitaxy (MBE) on atomically clean Si(111)-orientated substrates. The growth procedure involves the ambient temperature deposition of Ti films of 50Å thickness and annealing to 800°C. In situ low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) techniques have been used to monitor the TiSi2 formation process. The epitaxial films have been identified as the C49 metastable phase by both Raman spectroscopy and electron diffraction. Plan view transmission electron microscopy shows three different connected island morphologies. The individual island structures are single crystal and are grown epitaxially with different crystallographic orientations. The orientational relationship of the largest islands is given by [3 1 1] C49 TiSi2//Si and (130) C49 TiSi2//(l1 1)Si. High resolution transmission electron microscopy (HRTEM) cross-section shows a coherent interface extending over several hundred angstroms.
Epitaxial GaAs layers have been grown by molecular beam epitaxy on (1012) sapphire and silicon-on-sapphire substrates. The grown layers were characterized by optical and transmission electron microscopy; Rutherford backscattering/channeling of 2.1 MeV He+ ions; Raman spectroscopy; Hall mobility measurements; photoluminescence spectroscopy and current-voltage measurements from metal-semiconductor contacts. The extensive microstructural, electrical and optical analysis of the GaAs layers indicates that the films deposited on silicon-on-sapphire are superior to those grown directly on (1012) sapphire substrates.
The radiation hardness of small geometry (∼2 × 4 μm2), state of the art AlInAs/lnGaAs and GaAs/AlGaAs HBTs to 60Co γ-ray has been investigated up to a dose of 100 MRad. The former devices showed a small change in Ic and gain for 20 MRad, with essentially no change in IB. At 40 MRad, the gain of the devices had decreased to unity. By contrast, for GaAs/AlGaAs HBTs, the current gain actually increased up to a dose of 75 MRad. At 100 MRad, none of our devices were still operational. This was ascribed to degradation of the base-collector contact metallization (TiPtAu) and in particular to the presence of Au. Carbon-and beryllium-doped base devices showed the same response to 60Co γ-ray doses. No long transient responses in either base or collector currents were observed during irradiation of the GaAs/AlGaAs devices with 120 nsec pulses of 10 MeV electrons at rates up to 2.7 × 1010 Rad · sec−1. Results of a 2-dimensional modelling study suggest that both GaAs and InP based HBTs are relatively immune to damage by transient radiation effects up to a dose rate of 1011 Rad · sec−1, with GaAs based devices being more resistant to radiation than InP due to their shorter recombination times.
Epitaxial GaN films have been grown by plasma-enhanced chemical vapor deposition (PECVD). The growth procedure utilizes a He gas discharge combined with the down-stream introduction of trimethylgallium (TMGa) and nitrogen. Both cubic [1111 and wurtzitic  GaN epitaxial films have been achieved on (0001) sapphire substrates. Differences in substrate growth temperatures are believed to account for the different observed phases. A comparative study pertaining to the microstructural, optical and electrical properties of the α-GaN and β-GaN heteroepitaxial films is presented. Also reported for the first time is the Raman spectroscopy data for cubic GaN.
X-ray topography(XRT) and EBIC have been used to study the generation of misfit dislocations in strained layer structures. Two structures studied were GaAs1−yPy(y=0.15) film and SLS consisting of InxGa1−xAs(x=0.08) and GaAs1−y Py(y=0.16) layers. XRT and EBIC techniques gave consistent results for the behavior of dislocations. The value of the critical thickness for generation of misfit dislocations in the former was found to be few times larger than that in the latter. EBIC image showed that a SLS lattice matched to the substrate is effective in reducing defects originating from the substrate.