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In recent years, a number of experimental X-ray diffraction techniques have been developed by which a topographical display of the microscopical defects in a crystal can be obtained. This brief review of the most useful of these techniques is intended to summarize the elements of the various methods and to compare their respective features and limitations. Contrary to microradiographic methods, in which image contrast is due entirely to variations in X-ray absorption from point to point in the specimen, X-ray diffraction topography is concerned with point-topoint variations in the directions or the intensities of X-rays that have been diffracted by crystals. From these variations the defect structure of the crystal may be examined. Methods that mainly measure local variations in the direction of the diffracted beam are useful for the detection of gross misorientations such as subgrains or grains (methods of Gui nier and Tennevin, Schulz, Weissmann). Intensity mapping methods are chiefly concerned with individual defects such as dislocations, stacking faults, etc. In both groups there are experimental arrangements with both Laue-case (transmission) and Bragg-case (back reflection) geometry.
Background: When measuring young Duchenne Muscular Dystrophy (DMD) patients’ health-related quality of life (HRQoL), parent-proxy reports are heavily relied on. Therefore, it is imperative that the relationship between parent-proxy and child self-report HRQoL is understood. This study examined the level of agreement between children and their parent-proxy rating of the child’s HRQoL. Methods: We used FOR-DMD clinical trial baseline data. HRQoL, measured using the PedsQL inventory, was reported by 178 parent and child (ages 4 to 7 years) dyads. Intracorrelation coefficients (ICC) measured absolute agreement while paired t-tests determined differences in the average HRQoL ratings between groups. Results: The level of agreement between child and parent-proxy ratings of HRQoL was poor for the generic PedsQL scale (ICC: 0.29) and its subscales; and, similarly low for the neuromuscular disease module (ICC:0.16). On average, parents rated their child’s HRQoL as poorer than the children rated themselves in all scales except for psychosocial and school functioning. Conclusions: Child and parent-proxy HRQoL ratings are discordant in this study sample, as occurs in other chronic pediatric diseases. This should be taken into account when interpreting clinical and research HRQoL findings in this population. Future studies should examine reasons for parents’ perception of poorer HRQoL than that reported by their children.
Introduction: Ultrasound-guided intravenous (UGIV) insertion performed by nurses has been shown to be more effective than the blind approach for patients with difficult intravenous (IV) access in the emergency department (ED). While both the single-operator (SO) (where a single operator holds the IV and probe) and dual-operator (DO) (where a second operator holds the probe) techniques have been described, the DO is more resource-intensive, requiring a second operator to be present. The objective of this study is to compare the first-attempt cannulation success rates between a SO and DO technique in ED patients with predicted difficult access. Methods: We conducted a randomized controlled non-inferiority trial using a convenience sample of adult ED patients. Participating ED nurses received a one-hour UGIV training session including didactic and practical training on simulated arms. Patients were enrolled if they met any of three criteria for difficult access: (1) history of difficult access, (2) no visible or palpable veins, or (3) two failed blind attempts. Patients requiring active resuscitation, lack of suitable veins on US, or those unable to consent or comply with the procedure were excluded. Eligible patients were randomized to the SO or DO technique and a maximum of two UGIV attempts were allowed. The primary outcome was first-attempt success rate. Additional outcomes included overall success rate, number of attempts, time to successful cannulation, patient pain scores, operator ease of use scores, and complications 30 minutes after insertion. The chi-square test was used to compare success rates between groups and t-tests used for all other secondary outcomes. Results: 42 eligible patients have been approached for our study. 14 were excluded due to lack of visible veins on US or due to ongoing resuscitation. A total of 33 UGIV attempts were performed on 28 patients (17 in SO group, 16 in DO group). There was no statistically significant difference in first attempt success rates between the SO group of 76.5% (95% CI [50.1% to 93.2%]) and the DO group of 68.8% (95% CI [41.3% to 89%]) (p=0.62). There were also no statistically significant differences between the SO and DO groups in time to cannulation (140 vs 165 seconds, p=0.36), patient preference on a 10-point scale (7.0 vs 7.9, p=0.49), patient pain score (6.3 vs 6.6, p=0.87) or nursing ease of use (5.3 vs 6.5 p=0.23) respectively. There were no complications noted in either arm of the study. Conclusion: To date, the SO technique appears to be non-inferior to the DO technique for successful UGIV cannulation. Our results support the use of the SO technique, reducing the need for additional nursing resources when performing this procedure.
We present preliminary analysis of new HST observations of the transiting extrasolar planet HD 209458b. Photometric observations were obtained with the Fine Guidance Sensor (FGS) on the Hubble Space Telescope (HST), providing milli-mag precision and high time resolution (40 Hz). The FGS photometry allows us to derive precise stellar/orbital parameters (ephemeris, inclination, limb darkening) and planetary radius, and also allows a search for the presence of planetary rings and satellites. We discuss preliminary results and two approaches to modelling the observations.
Palaeomagnetic data define a polar wander path for the Dalradian tectonic block of the Scottish Highlands but resolve no relative motion between the Dalradian and Midland Valley blocks from early Ordo vician onwards. The history of structural episodes (D1 to D4) is traced for the Dalradian rocks of the Southern Highlands, and peak metamorphic temperatures are closely associated with D3 in the 520–490 Ma (early Ordovician) time period, whilst retrograde events are mostly associated with D4. Throughout the structural history, the influence of a lineament or lineaments parallel to the Highland Border is seen and is particularly demonstrated by the formation of the major Highland Border downbend (D4) structure. This monoform is interpreted as lying structurally above a major step in the basement and is associated with uplift of the Dalradian flat belt in the period 460–440 Ma (late Ordovician).
The mechanism of emplacement of the slivers of Highland Border Complex (HBC) rocks adjacent to the Dalradian Supergroup along the Highland Boundary fault zone is considered given that structural and palaeontological evidence indicates the emplacement to be post- D3 in the Dalradian rocks. The steep attitude of rocks along the Highland Boundary fault zone is probably due to vertical movements but either thrust or strike-slip movements are also indicated. Thrust emplacement prior to downbend formation (D4 in the Dalradian rocks) would also precede uplift and have to take place at considerable depth (10–20 km). Thrust emplacement subsequent to downbend formation is difficult to reconcile with the existing structural relations, whilst strike-slip motion offers a straightforward mechanism of placement.
Chemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare earth elements (REE) in hydrothermal veins at Adamello, (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major elements (determined by extraction with 9M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases. Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconolite. The results show that REE and actinides present in chemically resistant minerals can be retained under aggressive leaching conditions.
The sources of scattering losses in fluorozirconate glasses and fibers are reviewed. Results are presented which show that the predominant mechanism responsible for the presence of fluoride crystals is heterogeneous nucleation. The nature and origin of the different nuclei are discussed and possible ways to eliminate them from the glasses assessed. It is proposed that extreme care be employed in the processing of the glasses with particular emphasis on the preform fabrication step as this is critical to the design of ultra-low loss fibers.
This paper describes the instrumentation and technique for the routine characterization of thin Films, multi-layers and substrates by grazing incidence X-ray reflectometry with a rotating anode and CuKα1, line source. Ge 220 channel monochromators with two reflections per channel were used with one CM placed before and the other after the specimen. In many applications the second CM could be replaced with a narrow receiving slit. The specimen holder was designed to make fine translations of the specimen for alignment, a base was designed to permit precise positioning of the diffractometer, and a high-speed Rigaku scintillation counter was used. The alignment and calibration are described and some typical data given to illustrate the capability of the method.
In some radwaste applications, such as immobilization of U.S. Tank wastes using vitrification, Tc and Cs/Sr are likely to be separated out from HLW supernates. Simplified Synroc preparations can be devised for the immobilization of separated Tc and Cs/Sr, either together or individually. Under suitably reducing processing conditions, Tc can be immobilized, as metal or Tc4+. The volatility of Tc and Cs/Sr in Synroc processing is very restricted.
In Synroc-C, designed for Purex high-level reprocessing wastes, Tc exists as a metal alloy. In air-saturated water, normalized MCC-1 type total differential leach rates at 90°C decreased with leaching time and after 90 days were <10-4 g/m2/d, decreasing by a factor of ∼100 in anoxic conditions. The corresponding results in a pH=6.1 buffer solution were fairly similar to those in deionised water, but in anoxic conditions, the leach rates were higher in the buffer solution than in the deionised water.
A single perovskite phase was loaded with ∼40 wt% of TcO2 to form CaTc0.5Ti0.5O3 by a combination of graphite-die hot-pressing and heating in argon. Rutile, intended to be doped with ∼35wt% TcO2, was fabricated by bellows hot-pressing at 1200°C; aproximately 75% of the Tc formed a solid solution with rutile, but some metallic Tc was also present due to imperfect redox control. Results of both MCC-1 and PCT-type leach tests are presented on a preparation containing 70 wt% hollandite + 20 wt% perovskite + 10 wt% rutile containing about 5 wt% of Cs and Sr respectively. Phase distributions resulting from incorporating Cs and Sr in Synroc-B precursor were studied.
Leaching experiments with deionised water at 70°C have been carried out to ascertain the effect of oxidising and anaerobic conditions and the presence of Boom clay on Np release from Synroc.
The normalised solution leach rates of Np measured in these experiments are about a factor of 10 lower under reducing conditions than oxidising conditions and the presence of Boom clay was found not to enhance the leaching of Np from Synroc. Neptunium was found to be predominantly in the mobile fraction and was not removed from the leaching solutions significantly by filtration or ultrafiltration.