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Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion.
We report on follow-up observations of 20 short-duration gamma-ray bursts
(T90 < 2s) performed in
with the Gamma-Ray Burst Optical Near-Infrared Detector (GROND) between mid-2007 and the
end of 2010. This is the most homogeneous and comprehensive data set on GRB afterglow
observations of short bursts. In three cases, GROND was on target within less than 10 min
after the trigger, leading to the discovery of the afterglow of GRB 081226A and its faint
underlying host galaxy. In addition, GROND was able to image the optical afterglow and
follow the light curve evolution in five further cases: GRBs 090305, 090426, 090510,
090927, and 100117A. Three of the aforementioned six bursts with optical light curves show
a break: GRBs 090426 and 090510 as well as GRB 090305. For GRB 090927, no break is seen in
the optical/X-ray light curve until about 150 ks/600 ks after the burst. A decay slope of
the optical afterglow of GRB 100117A could be measured. Using these data supplemented by
about ten events taken from the literature, we compare the jet half-opening angles of long
and short bursts. We find a tentative evidence that short bursts have wider opening angles
than long bursts. However, the statistics are still very poor and follow-up observations
of these events are therefore very important to gain as much observational data as
To determine whether copper incorporated into hospital ward furnishings and equipment can reduce their surface microbial load.
A crossover study.
Acute care medical ward with 19 beds at a large university hospital.
Fourteen types of frequent-touch items made of copper alloy were installed in various locations on an acute care medical ward. These included door handles and push plates, toilet seats and flush handles, grab rails, light switches and pull cord toggles, sockets, overbed tables, dressing trolleys, commodes, taps, and sink fittings. Their surfaces and those of equivalent standard items on the same ward were sampled once weekly for 24 weeks. The copper and standard items were switched over after 12 weeks of sampling to reduce bias in usage patterns. The total aerobic microbial counts and the presence of indicator microorganisms were determined.
Eight of the 14 copper item types had microbial counts on their surfaces that were significantly lower than counts on standard materials. The other 6 copper item types had reduced microbial numbers on their surfaces, compared with microbial counts on standard items, but the reduction did not reach statistical significance. Indicator microorganisms were recovered from both types of surfaces; however, significantly fewer copper surfaces were contaminated with vancomycin-resistant enterococci, methicillin-susceptible Staphylococcus aureus, and coliforms, compared with standard surfaces.
Copper alloys (greater than or equal to 58% copper), when incorporated into various hospital furnishings and fittings, reduce the surface microorganisms. The use of copper in combination with optimal infection-prevention strategies may therefore further reduce the risk that patients will acquire infection in healthcare environments.
1. In streptococcal infection of piglets the causative agent (PM streptococcus) was isolated from the throats of a high proportion of infected animals and from their apparently healthy litter-mates.
2. The PM streptococcus was isolated from the noses of three out of forty-three normal sows. In one sow the streptococcus was also isolated from the throat.
3. Bacteriaemia was induced in piglets up to the age of 17 days by inoculating into the nose and throat broth cultures of the PM streptococcus. Blood cultures were usually positive within 24 hr., and secondary involvement of the joints and meninges frequently occurred during the ensuing few days.
4. Serum taken from piglets 5 weeks after experimental infection and administered subcutaneously protected susceptible piglets against subsequent infection with PM streptococci.
5. The possibility of preventing streptococcal infection in piglets by active immunization of the sow is discussed.
Poor fertility is a major problem on dairy farms. On-farm studies indicate than pregnancy rates to first service have declined from approximately 55% between 1975 and 1982 to 39% between 1995 and 1998 (Royal et al., 2000), illustrating a decline of approximately 1% per year during this period. The cause is multifactorial and influenced by many factors including genetics, management and nutrition. Previous studies have reported improved fertility through nutritional modification in early lactation (Gong et al., 2002). The aim of this study was to evaluate the effect of nutritional strategy in early lactation on reproductive performance.
Bone substitutes are often required to replace damaged tissue due to injuries, diseases and genetic malformations. Traditional bone substitutes, such as autografts, allografts, xenografts and metal implants, are far from ideal as each have their own specific problems and limitations. Bone tissue engineering offers a promising opportunity for bone regeneration in a natural way. However, currently the scientific challenges of bone tissue engineering lie in the development of suitable scaffold materials that can improve bone cell adhesion, proliferation and differentiation. The design of nanophase titania/polymer composites offers an exciting approach to combine the advantages of a degradable polymer with nano-size ceramic grains that optimize biological properties for bone regeneration. Importantly, nanophase titania mimics the size scale of constituent components of bone since bone itself is a nanostructured composite composed of nanometer hydroxyapatite crystals well-dispersed in a mostly collagen matrix. Previous studies have shown significant improvement in protein adsorption, osteoblast (bone-forming cell) adhesion and long-term functions on nano-grain ceramic materials compared to traditional micron-grain ceramic materials. This study used nanometer grain size titania dispersed in a model polymer (PLGA or poly-lactic-co-glycolic acid) matrix by using various sonication powers to increase osteoblast adhesion. The surface characteristics of the composites, such as topography, titania surface area coverage and surface roughness, were studied by scanning electron microscopy and atomic force microscopy. Of all the composites formulated in this study, osteoblast adhesion was the greatest on nanophase titania/PLGA (30/70 wt.%) sonicated at 118.75 for 10 minutes; this composite was the closest in terms of nanometer surface roughness compared to bone of all the composites formulated. In this manner, this study suggests that nanophase titania sonicated in PLGA under these conditions should be further studied for orthopedic applications.
Due to integration concerns, the use of meta-stable junction formation approaches like laser thermal annealing (LTA), solid phase epitaxial regrowth (SPER), and flash annealing has largely been avoided for the 90nm CMOS node. Instead fast-ramp spike annealing has been optimised along with co-implantation to satisfy the device requirements, often with the help from thin offset spacers. However for the 65nm and 45nm CMOS node it is widely accepted that this conventional approach will not provide the required pMOS junctions, even with changes in the transistor architecture.
In this work, we will compare junction performance and integratablity of fast-ramp spike, flash, SPER and laser annealing down to 45nm CMOS. The junction depth, abruptness and resistance offered by each approach are balanced against device uniformity, deactivation and leakage. Results show that the main contenders for the 45nm CMOS are SPER and flash annealing – but both have to be rigorously optimised for regrowth rates, amorphous positioning and dopant and co-implant profiles. From the two, SPER offers the best junction abruptness (<1nm/dec) with leakage suitable for low power applications, while the flash anneal has the benefit of higher solid solubility (>4E20at/cm3) and less transistor modifications. As expected, Ge and F co-implanted spike annealed junctions do not reach the 45nm node requirements. For full-melt LTA, poly deformation on isolation can be reduced but geometry effects result in unacceptable junction non-uniformity.
In an attempt to overcome infections associated with central venous catheters, a new antiseptic central venous catheter coated with benzalkonium chloride on the internal and external surfaces has been developed and evaluated in a clinical trial. Patients (235) randomly received either a triple-lumen central venous catheter coated with benzalkonium chloride (117) or a polyurethane non-antiseptic catheter (118). The incidence of microbial colonization of both catheters and retained antiseptic activity of the benzalkonium chloride device following removal were determined. The benzalkonium chloride resulted in a significant reduction of the incidence of microbial colonization on both the internal and external catheter surfaces. The reduction in colonization was detected at both the intradermal (21 benzalkonium chloride catheters vs. 38 controls, P=0.0016) and distal segments of the antiseptic-coated catheters. Following catheter removal retained activity was demonstrated in benzalkonium chloride catheters which had been in place for up to 12 days. No patients developed adverse reactions to the benzalkonium chloride catheters. The findings demonstrate that the benzalkonium chloride catheter significantly reduced the incidence of catheter-associated colonization.
The application of non-equilibrium transport techniques to Molecular Beam Epitaxy (MBE) grown InSb/InAlSb heterostructure diodes has produced practical devices such as midinfrared LED's and negative luminescent sources that operate at room temperature. By extending the epitaxial growth to vicinal InSb substrates it has been demonstrated that the temperature window for high quality epitaxy can be lowered by ∼12°C, giving greatly improved epilayer morphology. The degree of misorientation needed for given growth temperatures is shown from Atomic Force Microscope (AFM) measurements to be only ∼2°. In addition, the lower growth temperature gives improved dopant activation, lower trap densities and lower reverse bias leakage currents, with consequent benefits to device performance.
This paper is an interim report of our inferences about the hydrostatic structure of the Sun, following the first report of the GONG team in Science (Gough et al., 1996). That work confirms that the spherically averaged structure of the Sun is more or less in agreement with current standard solar models. However, there remain some significant deviations which we regard as important clues to the existence of dynamical phenomena which are not taken into account in standard solar modelling.
The CANTAB battery of neuropsychological tests was used to compare the performance of 28 patients with unipolar depression with that of 22 age and IQ matched controls. The patients were impaired on almost all tests studied with deficits in pattern and spatial recognition memory, matching to sample, spatial span, spatial working memory and planning. Most of the patients showed at least some impairment and deficits were seen across cognitive domains. An important finding was the detrimental effect of failure on subsequent performance; having solved one problem incorrectly, patients were far more likely than controls to fail the subsequent problem. Superimposed on the general deficits, there were also specific deficits in executive tasks characteristic of frontostriatal dysfunction and deficits in mnemonic tasks characteristic of temporal lobe dysfunction. This combination of a specific form of motivational deficit, resulting in oversensitivity to negative feedback, and superimposed specific neuropsychological deficits were correlated with severity of depression. The most significant correlations were seen between mnemonic deficits and clinical rating scores. Comparisons of the deficits seen in the depressed patients in this study with other patient groups assessed with the CANTAB neuropsychological battery, showed that one of the hypotheses of the neuropsychological deficits in depression, that of ‘frontosubcortical’ or ‘frontostriatal’ dysfunction, was not supported. These findings are discussed in relation to the likely neural substrates of depression.
Major fluvial palaeovalleys located in transfer zones that link sediment-producing hinterlands with depositional basins are an important, but neglected, element of fluvial systems. Studies of present-day examples are limited and, to date, no examples have been described from the geological record. Tertiary syn-orogenic fluvial successions in the Spanish Pyrenees include regional-scale, unconformably-based, linear bodies of conglomerate interpreted as transfer zone palaeovalleys. These palaeovalleys are sited mainly in the external zones of the mountain belt, between the internal, Axial Zone on which the drainage basin was largely established and the depositional basins. One palaeovalley, here termed the Sis palaeovalley, is located in a growth syncline between two thrust-related, lateral structures. Subsidence within the syncline permitted a 1400 m plus succession of clast-supported cobble conglomerates to accumulate during an 11–21 Ma period (Middle Eocene to Oligo–Miocene). This palaeovalley served not one, but a series of evolving thrust-sheet-top and foreland basins during this period. The stability of the palaeovalley was governed by its structural siting which, using evidence from the stratigraphy immediately underlying the palaeovalley, is considered to be a long-lived lineament which was re-used during compressional deformation. An appreciation of the location and evolution of the palaeovalley has the potential to contribute significantly towards a better understanding of the development of the Pyrenean orogen.
Self aligned refractory metal silicides such as titanium disilicide have been used extensively in VLSI and ULSI structures. Unlike earlier work which has relied on undoped substrates and a single implant species, in the present study TiSi2 formation on phosphorous doped poly-Si in the presence of multiple dopants has been investigated. TEM micrographs are discussed which show the difference in silicide formation for the case of the BF2 and arsenic implanted samples. We have found that the presence of fluorine in the BF2 implant retards the silicide formation for phosphorous doped poly-Si substrates. Additionally, the effect of substrate grain size on TiSi2 formation has been investigated using undoped α-Si and poly-Si substrates.