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61.
Wenjun Liu Gene E. Ice Bennett C. Larson Wenge Yang Jonathan Z. Tischler J. D. Budai 《Metallurgical and Materials Transactions A》2004,35(7):1963-1967
The three-dimensional (3-D) X-ray crystal microscope is a new nondestructive tool for the 3-D characterization of the mesoscopic
and nanoscopic materials structure. A prototype microscope is installed on beamline 34-ID at the advanced photon source and
has begun initial operation. The prototype microscope has a routine spatial resolution of approximately 0.5 × 0.5 × 1 μm3 and can probe tens to hundreds of microns below a sample surface, depending on the composition of the sample. For each volume
element measured, the microscope can determine between 10 and 16 parameters. The measured parameters are the local crystallographic
phase (1 deg of freedom), the Eulerian angles of crystal orientation (3 deg of freedom), and the plastic and/or elastic strain-tensor
elements (6 to 12 deg of freedom). The time required to collect each volume element varies between 1 and 14 seconds, depending
on the precision of the parameters and the sample complexity. Much faster data acquisition and much better spatial resolution
are certain in the near future. Some initial results are presented to illustrate how the 3-D X-ray crystal microscope can
provide unprecedented information about the 3-D structure of materials.
This article is based on a presentation made at the symposium “Characterization and Representation of Material Microstructures
in 3-D” held October 8–10, 2002, in Columbus, OH, under the auspices of ASM International’s Phase Transformations committee. 相似文献
62.
A compartmental and non-compartmental study was carried out on five adult goats following intramuscular administration of doxycycline at 20 mg/kg bodyweight. The concentration of the drug in serum was determined by a microbiological assay employing Bacillus cereus var mycoides (ATCC 11778) as the test organism. The mean serum concentration (Cmax) and the time of maximum concentration (Tmax) were 1.87 micrograms/ml and 0.85 h, respectively. Using compartmental analysis, the plasma concentration-time curve of doxycycline best fitted a three-compartment open model with first-order absorption. A three-phase disposition of doxycycline was found, the terminal elimination half-life being approximately 40 h. The statistical moment theory was mainly used for non-compartmental analysis. The value obtained for the mean residence time (MRT) was 16.4 h. The mean values for the volume of distribution at steady state (Vdss), determined by compartmental and non-compartmental analyses, were 8.73 and 13.19 L/kg, respectively. There were no statistically significant differences when the major pharmacokinetic parameters were compared. It was concluded that the pharmacokinetic behaviour of doxycycline in goats after intramuscular administration is characterized by a three-compartment model with a slow terminal elimination phase. Based on current knowledge, this could be due to enterohepatic recycling and/or flip-flop kinetics. The study indicated that a single intramuscular administration of 20 mg/kg of doxycycline may only provide therapeutic concentrations for up to 24 h owing to slow absorption at the injection site. 相似文献
63.
Here we analyze the problem of determining whether experimentally measured spontaneous miniature end-plate currents (MEPCs) indicate that quanta are composed of subunits. The properties of MEPCs at end plates with or without secondary clefts at the neuromuscular junction are investigated, using both stochastic and deterministic models of the action of a quantum of transmitter. It is shown that as the amount of transmitter in a quantum is increased above about 4000 acetylcholine (ACh) molecules there is a linear increase in the size of the MEPC. It is possible to then use amplitude-frequency histograms of such MEPCs to detect a subunit structure, as there is little potentiation effect above 4000 ACh molecules. Autocorrelation and power spectral analyses of such histograms establish that their subunit structure can be detected if the coefficient of variation of the subunit size is less than about 0.12 or, if electrical noise is added, about 0.1. Positive gradients relate the rise time and half-decay times of MEPCs to their amplitude, even in the absence of potentiating effects; these gradients are shallower at motor nerve terminals that possess secondary clefts. The effect of asynchronous release of subunits is also investigated. The criteria determined by this analysis for identifying a subunit composition in the quantum are applied to an amplitude-frequency histogram of MEPCs recorded from a small group of active zones at a visualized amphibian motor-nerve terminal. This did not provide evidence for a subunit structure. 相似文献
64.
D. Bennett 《Materials science & engineering. C, Materials for biological applications》2011,31(2):494-498
A recipe for manipulating the conductivity of agar impedance-imaging phantoms through their NaCl (salt) content is reexamined. The conductivities at frequencies 100 kHz and below are characterized for phantoms created with the recipe. The data are compared against the recipe's predictive formula for conductivity as a function of salt content. Based on analysis of the data a modified version of the conductivity formula is generated. The modified predictive formula better approximates the observed NaCl dependence of conductivity in phantoms with salt concentrations under 0.1 M. The experimental data also provide verification for the asymptotic dependence of contact impedance on frequency and phantom conductivity. The results of these experiments will be helpful in better constructing agar phantoms to electrical specifications for future impedance-imaging experiments. 相似文献
65.
Yingping Huang Ross McMurran Mark Amor-Segan Gunwant Dhadyalla R. Peter Jones Peter Bennett Alexandros Mouzakitis Jan Kieloch 《The International Journal of Advanced Manufacturing Technology》2010,51(1-4):233-246
A current premium vehicle is implemented with a variety of information, entertainment, and communication functions, which are generally referred as an infotainment system. During vehicle development, testing of the infotainment system at an overall level is conventionally carried out manually by an expert who can observe at a customer level. This approach has significant limitations with regard to test coverage and effectiveness due to the complexity of the system functions and human’s capability. Hence, it is highly demanded by car manufacturers for an automated infotainment testing system, which replicates a human expert encompassing relevant sensory modalities relating to control (i.e., touch) and observation (i.e., sight and sound) of the system under test. This paper describes the design, development, and evaluation of such a system that consists of simulation of vehicle network, vision-based inspection, automated navigation of features, random cranking waveform generation, sound detection, and test automation. The system developed is able to: stimulate a vehicle system across a wide variety of initialisation conditions, exercise each function, check for system responses, and record failure situations for post-testing analysis. 相似文献
66.
67.
Richard M. Gunner Rory P. Wilson Mark D. Holton Phil Hopkins Stephen H. Bell Nikki J. Marks Nigel C. Bennett Sam Ferreira Danny Govender Pauli Viljoen Angela Bruns O. Louis van Schalkwyk Mads F. Bertelsen Carlos M. Duarte Martin C. van Rooyen Craig J. Tambling Aoife Gppert Delmar Diesel D. Michael Scantlebury 《Journal of the Royal Society Interface》2022,19(186)
The combined use of global positioning system (GPS) technology and motion sensors within the discipline of movement ecology has increased over recent years. This is particularly the case for instrumented wildlife, with many studies now opting to record parameters at high (infra-second) sampling frequencies. However, the detail with which GPS loggers can elucidate fine-scale movement depends on the precision and accuracy of fixes, with accuracy being affected by signal reception. We hypothesized that animal behaviour was the main factor affecting fix inaccuracy, with inherent GPS positional noise (jitter) being most apparent during GPS fixes for non-moving locations, thereby producing disproportionate error during rest periods. A movement-verified filtering (MVF) protocol was constructed to compare GPS-derived speed data with dynamic body acceleration, to provide a computationally quick method for identifying genuine travelling movement. This method was tested on 11 free-ranging lions (Panthera leo) fitted with collar-mounted GPS units and tri-axial motion sensors recording at 1 and 40 Hz, respectively. The findings support the hypothesis and show that distance moved estimates were, on average, overestimated by greater than 80% prior to GPS screening. We present the conceptual and mathematical protocols for screening fix inaccuracy within high-resolution GPS datasets and demonstrate the importance that MVF has for avoiding inaccurate and biased estimates of movement. 相似文献
68.
69.
ES el Daly 《Canadian Metallurgical Quarterly》1996,51(4):195-199
Eleven patients suffering from chronic disabling tinnitus underwent an FDG-PET study (positron emission tomography with [18F]deoxyglucose). Nine tinnitus patients revealed a significantly increased metabolic activity in the left, 1 in the right primary auditory cortex (PAC, Brodmann area 41). These results were statistically significant when compared to 14 healthy control individuals without tinnitus. A negative result was obtained from a chronic tinnitus patient but who had no subjective complaints during the period of PET investigation. One patient was first investigated during a disabling tinnitus period, later during a period with tinnitus relief and again when suffering from severe tinnitus. The metabolic activity of his left PAC was in good accordance with the subjective degree of tinnitus complaints present during each PET investigation. Although for the first time these results give objective evidence of tinnitus sensation and localization, they are difficult to interpret because of the limited research data available that combine functional brain imaging and acoustic stimuli. 相似文献
70.
RR Frazier ES Millican SK Watson NJ Oldroyd RL Sparkles KM Taylor S Panchal L Bark CP Kimpton PD Gill 《Canadian Metallurgical Quarterly》1996,17(10):1550-1552
The Applied Biosystems (ABI) Prism 377 DNA sequencer has been evaluated in an attempt to increase the throughput of samples for short tandem repeat (STR) analysis, in both forensic casework and the UK National Criminal Intelligence DNA Database. The gel system assessed consisted of 0.2 mm, 4% acrylamide 6 M urea gels, with a well-to-read distance of 36 cm. Gels were run at a constant voltage of 3 kV and constant temperature of 51 degrees C. The run time of our second generation multiplex (SGM) STR system was achieved in less than 2 h. Rigorous validation has been performed on the instrument hardware and software. Complete resolution of 1 base differences was obtained, up to and beyond 350 bases; sizing precision across gels was more than 2-fold higher than the 373A and the sensitivity was increased by one third. 相似文献