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X-ray diffraction techniques have been used for the structure characterization of Y-Ba-Cu-O and Tl-Ca-Ba-Cu-O thin films. A powder diffraction analysis of Y-Ba-Cu-O films showed that the films deposited at 650°C on Si are polycrystalline and have an orthorhambic structure similar to that of the YBa2Cu3O7 bulk superconductors. In addition to the conventional powder diffraction technique, both the rocking curve and the grazing incidence diffraction methods were used to characterize a YBa2Cu3O7 film on (110) SrTiO3 substrate. Results showed that the film was epitaxially grown and aligned with its substrate in a true epitaxy. Phase identification and line broadening analyses of Tl-Ca-Ba-Cu-O films showed that the films are comprised of one or more superconducting phases and probably contain stacking faults.
The purpose of this study was to develop a theoretical explanation of the process of becoming a father and how this impacted on smoking behaviours of men during their partner's pregnancy. Grounded theory method and constant comparative analysis was used to explain data from interviews with 23 men from rural Midwest USA. Becoming a father prompted participants to seek ways to protect their partners and babies from the effects of cigarette smoking. First-time fathers were particularly receptive to quitting smoking early in their partner's pregnancy, whereas motivation to quit declined as pregnancy progressed for first-time fathers and other fathers. Although protecting their families from cigarette smoke remained constant, men's smoking goals and behaviours became increasingly focused on minimising harm rather than quitting as their partner's pregnancy progressed. Findings support the view that the transition to fatherhood is an opportune time in which to encourage and support smoking behaviour change for male partners. Theoretical insights provide understanding of why and when expectant fathers attempt to quit smoking and reduce harm to their families. Future research should focus on appropriate and timely interventions to maximise the success of men to quit smoking when they are naturally motivated to do so.
The advent of polymer electrolytes has provided a promising route to an all solid-state polymer battery. Such a battery would have greater safety, without potential discharge of liquid or gel electrolyte. Current battery configurations typically involve a metal anode, a solvent-plasticized polyelectrolyte, such as poly (ethylene oxide) (PEO), and a composite cathode. We have synthesized an A/B/C triblock copolymer which could have potential use as an all-solid state nanoscale polymer lithium battery. The polymeric battery was synthesized with an anode, electrolyte and cathode by synthesizing an A/B/C triblock copolymer whose microphase separation would form lamellar domains. These nanodomains contain cobalt oxide, a derivative of PEO synthesized by ring opening metathesis polymerization, and a spinel phase LiMn2O4 as the anode, electrolyte and cathode material, respectively. The first block contains cobalt oxide that stores lithium ion in a novel electrochemical reaction that allows use in a battery configuration. The second block is polyethylene oxide derived from an unsaturated crown ether, and is used for its high ionic conductivity. The third block contains LiMn2O4, which is currently being investigated as a potential cathode material because of its low toxicity and ease of preparation. The nanometer size domains in the battery can be used in unique applications in microelectronics. In addition, such size scale allows use of the battery in discrete circuits, reducing the amount of wiring necessary in conventional battery configurations.
An extensive study of contacts properties to undoped and doped hydrogenated amorphous silicon, undertaken in our laboratory, has shown that ohmicity and contact quality are very dependent on the reactivity of the metal and the quality of the metal / a-Si:H interface. For example, metals such as Sc, Mg or Ti form exceptionally good ohmic (very low barrier height) contacts, while others like Al, Cu, Mo or V form very poor quasi-ohmic contacts (average barrier height) to undoped films. In addition, metals such as Y, Ho, Hf or Er create fair quasi-ohmic (low barrier height) contacts to undoped films, at room temperature. The barrier height and the magnitude of current density can be adjusted to some degree not only by the proper choice of metal work function but also by changing material bulk resistivity or/and interface quality. Consequently, specific attention is devoted to these parameters which not only determine the quality of ohmic contact but also the dominant conduction mechanism across the barrier.
Photolysis of Si2H6 by an ArF excimer laser has been used to deposit Si homoepitaxial layers at temperatures as low as 300°C. The chemical vapor deposition process at growth rates from 0.5-4 Å/minute is performed in an ultra-high vacuum chamber which, along with an ex situ HF dip and a novel in situ hydrogen clean using laser excitation, results in minimization of oxygen and carbon contamination which inhibits Si epitaxy. The growth involves photolytic decomposition of Si2H6 and the generation and adsorption of SiH2 precursors on the hydrogenated Si surface, which is the rate limiting step. Growth rates are observed to vary proportionally with laser power. Very low defect density films in terms of stacking faults and dislocation loops (less than 105 cm−2), and excellent crystallinity have been deposited as confirmed by Schimmel etching and Nomarski microscopy, transmission electron microscopy, electron diffraction and in situ reflection high energy electron diffraction.
In this paper we develop a model of the defect kinetics in hydrogenated Amorphous silicon (a:Si:H) with the goal of predicting the density of defect states g (E) established by any given light intensity I, for arbitrary times t and temperatures T. While we build on widely accepted expressions for the the rates of light-induced and thermal annealing, we examine in more detail the light induced annealing (LIA) term. The model shows that the LIA process can be described with the thermal annealing term if a suitable reduction to the annealing energy is introduced. This reduction depends on the light intensity such as to suggest a relation to the shift of the electron quasi-Fermi level under illumination.
When an ocean wave breaks against a steep-fronted breakwater, sea wall or a similar marine structure, its impact on the structure can be very violent. This paper describes the theoretical studies that, together with field and laboratory investigations, have been carried out in order to gain a better understanding of the processes involved. The wave's approach towards a structure is modelled with classical irrotational flow to obtain the different types of impact profiles that may or may not lead to air entrapment. The subsequent impact is modelled with a novel compressible-flow model for a homogeneous mixture of incompressible liquid and ideal gas. This enables a numerical description of both trapped air pockets and the propagation of pressure shock waves through the aerated water. An exact Riemann solver is developed to permit a finite-volume solution to the flow model with smallest possible local error.
The high pressures measured during wave impacts on a breakwater are reproduced and it is shown that trapped air can be compressed to a pressure of several atmospheres. Pressure shock waves, reflected off nearby surfaces such as the seabed, can lead to pressures comparable with those of the impact. Typical examples of pressure-time histories, force and impulse are presented and discussed in terms of their practical implications. The numerical model proposed is relevant for a variety of flows where air effects are important. Further applications, including extended studies of wave impacts, are discussed.
Hannah Barrett, University Department of Anaesthesia & Intensive Care Medicine N5 Queen Elizabeth Hospital Edgbaston Birmingham B15 2TH UK,
Alison D. Bullock, School of Education University of Birmingham Edgbaston Birmingham B15 2TT UK,
Julian F. Bion, University Department of Anaesthesia & Intensive Care Medicine N5 Queen Elizabeth Hospital Edgbaston Birmingham B15 2TH UK
Making judgements about ourselves and others is a universal human phenomenon repeated daily in social intercourse, examination halls, or courts of law. It is the desire to do this in an objective, repeatable, reliable and constructive manner that underpins the principle of professional self-regulation. However, this principle has been challenged by evidence of error in healthcare worldwide, and in the UK by several high-profile individual failures which have exposed flaws in regulatory systems. The subsequent public enquiries and their reports have stimulated modifications to training and assessment including regular appraisal and continuing professional development to ensure competence, introduction of a national system for reviewing doctors in difficulty, and several reviews of the concept of professionalism. In short, we will only retain the high level of public trust currently accorded to the medical profession if we combine effective assessment of competence with continued monitoring of performance. Assessment is thus an essential part of ensuring safe and effective patient care.
So much is obvious. But are we not doing this already? The medical profession has from earliest times made a commitment to place the interests of the patient before those of the practitioner and to maintain the highest standards of practice through examination and peer review. The problem is that this commitment may not be shared by all members of the profession. The absence of explicit standards and transparency makes assessment of performance difficult and therefore limits accountability.
We show initial results from our ongoing HST/ACS GHOSTS survey of the resolved stellar envelopes of 14 nearby, massive disk galaxies. In hierarchical galaxy formation the stellar halos and thick disks of galaxies are formed by accretion of minor satellites and therefore contain valuable information about the (early) assembly process of galaxies. We detect for the first time the very small halo of NGC 4244, a low mass edge-on galaxy. We find that massive galaxies have very extended halos, with equivalent surface brightnesses of 28-29 V-mag arcsec−2 at 20-30 kpc from the disk. The old RGB stars of the thick disk in the NGC 891 and NGC 4244 edge-on galaxies truncate at the same radius as the young thin disk stars, providing insights into the formation of both disk truncations and thick disks. We furthermore present the stellar populations of a very low surface brightness stream around M83, the first such a stream resolved into stars beyond those of the Milky Way and M31.
Preparation of large quantities of RNA molecules of a defined
sequence is a prerequisite for biophysical analysis, and is
particularly important to the determination of high-resolution
structure by X-ray crystallography. We describe improved methods
for the production of multimilligram quantities of homogeneous
tRNAs, using a combination of chemical synthesis and enzymatic
approaches. Transfer RNA half-molecules with a break in the
anticodon loop were chemically synthesized on a preparative
scale, ligated enzymatically, and cocrystallized with an
aminoacyl-tRNA synthetase, yielding crystals diffracting to
2.4 Å resolution. Multimilligram quantities of tRNAs with
greatly reduced 3′ heterogeneity were also produced via
transcription by T7 RNA polymerase, utilizing chemically modified
DNA half-molecule templates. This latter approach eliminates
the need for large-scale plasmid preparations, and yields
synthetase cocrystals diffracting to 2.3 Å resolution
at much lower RNA:protein stoichiometries than previously required.
These two approaches developed for a tRNA–synthetase complex
permit the detailed structural study of “atomic-group”
Three ambulant males with multicore myopathy, a rare congenital myopathy, are reported with nocturnal hypoventilation progressing to respiratory failure at the age of 9, 13, and 21 years. Deterioration in these individuals occurred over several months without any precipitating event. Patients had clinical evidence of nocturnal hypoventilation with hypoxaemia and hypercapnia. Forced vital capacity was significantly reduced (20 to 43% of predicted level). These parameters improved on institution of overnight ventilation using a BiPAP pressure support ventilator with face mask or nasal pillows with O2 saturation maintained above 90% overnight and an increase in forced vital capacity by as much as 100% (0.3 to 0.6 litres). This was matched by a symptomatic and functional improvement. Also present in these patients and not previously reported is the association of multicore myopathy with paraspinal contractures which produce a characteristic scoliosis described as a ‘side-sliding’ spine. This may be improved by spinal bracing or surgery.
The Seychelles Warbler was once a highly threatened single-island endemic species with a population of 26 individuals confined to Cousin Island in the inner Seychelles. Following long-term management of Cousin, the population steadily recovered to around 300- 360 birds. Given the vulnerability of one small island in the Indian Ocean, the possibility of establishing the species on additional islands had been proposed as a priority conservation measure. This paper describes the successful translocation of 29 Seychelles Warblers from Cousin to Aride, summarizes the ecological studies carried out prior to, during and after the translocation and documents the subsequent establishment of the new population. It is considered that the Seychelles Warbler will soon no longer be a globally threatened species.
This paper describes the incidence and pathology of a copepod parasite (Sarcotaces sp.) in two species of deep-sea bottom-living fish. The fish Lepidion eques (Moridae) and Coelorynchus occa (Macrouridae) are common on the continental slope to the west of the British Isles at depths from about 400 to 1300 m and 700 and 2000 m respectively.
In both species the parasite was located beneath the skin. In L. eques it was found primarily on the head, whereas in C. occa it was present on the mid to lower flank, often close to the anal vent. Excision of the parasite from the host tissue showed it to consist of a pyriform sac filled with inky black fluid. Detailed histological investigations revealed the parasite wall to be a highly complex structure. Within the gut fluid shown to be of haematogenous origin, numerous copepod nauplii were often observed.
The histology and histochemistry of whiting skin was studied in larval, juvenile and adult fish. The adult specimens were obtained throughout the year but there was no evidence of seasonal variation in the areas of the body sampled. The skin of the whiting is considerably more complex than that of any other teleost fish which has been described in detail. The epidermis of the mature fish comprises five layers, consisting of Malpighian cells and a variety of other structures including large cystic bullae, which ultrastructurally and histochemically are relatively amorphous but comprise a major proportion of the epidermis. A reticulum of epidermal melanocytes occurs above these structures and two types of mucous cell are described. The major histochemical feature of the epidermis was the alkaline phosphatase reaction, similar to that found in higher animals. Succinic dehydrogenase activity was found at all levels. The epithelial mucins were mainly acid mucopolysaccharide with a small sialic acid component and a greater proportion of sulphated muco-substance. The dermis was morphologically similar to that of other scaled fishes. Mast cells were particularly prominent and occasional non-pigmented ‘melanophores’ were seen.
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