The effect of the choice of maternal age-specific prevalence curve on the model predicted Down syndrome detection rate was examined. All 19 published regression curves from 11 birth prevalence series in four meta-analyses were included. The detection rate for a five per cent false-positive rate was estimated for three combinations of markers. For free beta human chorionic gonadotropin and alpha-fetoprotein the lowest predicted detection rate was 62.3 per cent and the highest 64.1 per cent, a range of 1.8 per cent. When unconjugated oestriol was added as a third marker it was 65.6-67.3 per cent, a 1.7 per cent range, and when inhibin A was the fourth marker the detection rate was 72.0-73.4 per cent, a 1.4 per cent range. The number of series included in the regression had the biggest effect: when the authors had used a subset thought to have the highest ascertainment the predicted detection rate generally increased. The type of regression equation used and restrictions on the age range over which the regression was performed were less important factors. The effect of the choice of curve on the predicted increase in detection achieved by incorporating additional markers was relatively small: 3.1-3.3 per cent for unconjugated oestriol and a further 6.1-6.5 per cent for inhibin A. This analysis shows that the model inaccuracy caused by the maternal age curve is not small but is unlikely to be large enough to influence Down syndrome screening policy decisions. 相似文献
A high-power CW 27.972 μm water-vapor laser has been developed for interferometric and polarimetric measurements of plasmas. The maximum output power and the power density in the cavity of the laser with 2.0 cm bore and 220 cm length reach 85 mW and 109 μW/cm3, respectively. An interferometer using this laser is constructed and its performance is examined as a study on polarimetric method of magnetic field measurement. Preliminary interferometric experiments are also carried out on a compact toroidal plasma with field-reversal configuration. 相似文献
Many circular motion measuring methods for NC machine tools have been proposed, however, the drawback common to many of these methods is the restriction on the radius size due to the short measuring range of the displacement transducers used. Moreover, most of these measurement tools are specialized, and can only perform circular test path measurements. A circularity test method using a laser displacement interferometer and a rotary encoder has been developed. The measuring method features a much longer range of motion than ordinal circular test methods such as the double ball bar (DBB) method and, therefore, the radius restriction on these measurements is greatly reduced. Moreover, this measuring system can also be used for the evaluation of positioning accuracy and other more complex test paths.
The proposed device consists primarily of a laser displacement interferometer and a rotary encoder. The holders for the interferometer head and the retroreflector are connected with a stainless steel rod. The retroreflector holder has a synthetic resin linear bearing allowing it to move relative to the interferometer head so that both optical components are always facing each other. The laser interferometer measures the change in distance between the interferometer head and the retroreflector, and the rotary encoder measures the rotation angle of the stainless steel rod.
In this paper, the background, measuring principle and apparatus structure are briefly described. The experimental setup is also presented. The apparatus was employed in several measuring experiments, including circularity tests for a vertical machining center. The results from these experiments support the validity of this measurement apparatus. 相似文献
In a preliminary open-label trial by our group, Bifidobacterium bifidum YIT 10347 (YIT10347) relieved gastric symptoms in patients with functional gastrointestinal disorders. Hence, in this study, we investigated the effects of YIT10347 on gastrointestinal symptoms in healthy adults. In this prospective double-blind, randomized, placebo-controlled trial (UMIN000024654), 100 healthy Japanese adults were randomly assigned to a YIT10347 group or placebo group and consumed 100 mL of YIT10347-fermented milk or placebo fermented milk, respectively, every day for 4 wk. Gastrointestinal symptoms were evaluated by using the modified Frequency Scale for Symptoms of Gastroesophageal Reflux Disease (m-FSSG) and Gastrointestinal Symptom Rating Scale (GSRS) as primary endpoints. Mental symptoms, quality of life, salivary stress markers, and gastric emptying were evaluated as secondary endpoints. Effectiveness and safety were analyzed in a per-protocol set (YIT10347 group, n = 39; placebo group, n = 40) and full analysis set (YIT10347 group, n = 50; placebo group, n = 50), respectively. In the m-FSSG evaluation, the YIT10347 group had a significantly higher relief rate of postprandial discomfort and greater changes in postprandial epigastric pain score from baseline than the placebo group. In the GSRS evaluation, the YIT10347 group had significantly higher relief rates of overall gastrointestinal symptoms, upper gastrointestinal symptoms, flatus, and diarrhea than the placebo group. We detected no significant differences in scores or relief rates of mental symptoms and quality of life, a salivary stress marker, or gastric emptying between the 2 groups. No severe adverse events associated with test beverage consumption were observed in either group. These findings suggest that daily consumption of YIT10347-fermented milk exerts beneficial effects on gastrointestinal discomfort and symptoms such as postprandial discomfort and epigastric pain in healthy adults. 相似文献
A high performance liquid chromatographic (HPLC) method is described for separation and quantitation of 1-alkyl-3-acyl- and
1-alkyl-2-acyl-sn-glycerol, products of the detritylation reaction of 1-alkyl-2-acyl-3-trityl-sn-glycerol. The alkyl glycerides were separated on a 25 cm×4.6 mm ID column packed with ∼5–6 μm silica and eluted isocratically
with isooctane/isopropanol (98∶2, v/v) as mobile phase. The good separation and linear refractive index (RI) detector responses
using cholesterol as an internal standard indicated the applicability of the method not only for the quantitative determination
of the alkylglycerols but also for their semipreparative isolation. This HPLC method shows excellent reproducibility and accuracy
and is applicable to other types of glycerides such as mono- and diacylglycerols.
Presented in part at the AOCS annual meeting, Honolulu, Hawaii, May 1986. 相似文献
Genetic alteration, including genomic instability, is an ultimate step toward the malignant process. One approach to delineating replication errors in cancer cells is to determine the alterations of microsatellites, which are short, repeated nucleotide sequences existing throughout the genomes. We used a fluorescent system to assess microsatellite changes in seven loci (D2S123, D3S643, D5S107, LPL, D17S261, TP53, and D18S34) of 73 consecutive patients with various hematological neoplasias. De novo acute leukemia patients had a low frequency (<1%) of microsatellite alterations at each locus, and none of them demonstrated multiple microsatellite changes. In chronic myeloid leukemia patients, no microsatellite instability was detected in the chronic phase, whereas a relatively high frequency (25%) of multiple microsatellite changes was evident in the blastic phase, and half of these patients had multiple microsatellite changes. About 50% of the patients with myelodysplastic syndrome (MDS) and post-MDS acute myeloid leukemia (post-MDS AML) had microsatellite alterations. We next compared microsatellite alterations in two different hematological phases (MDS and post-MDS AML phases); 5 of 11 patients with post-MDS AML had de novo appearance of microsatellite instability during disease progression. This indicates that genomic instability at multiple microsatellite loci could occur either before or after leukemic transformation in MDS patients. We concluded that genomic instability in chronic myeloid leukemia might be linked to blastic transformation in combination with cytogenetic changes. In contrast, MDS patients had replication errors as a relatively early genetic event as well as a late genetic event. These results suggest that the involvement of genomic instability in the progression of disease is different among various types of leukemia. 相似文献
The effects of experimental conditions and acid catalysts on the removal of the trityl group of 1-alkyl-2-acyl-3-trityl-sn-glycerols to yield 1-alkyl-2-acyl-sn-glycerols have been investigated. Removal of the trityl protecting group was complicated by the concomitant migration of
the 2-acyl moiety to yield the 1-alkyl-3-acyl-sn-glycerol isomer. The course of detritylation as well as the extent of the 2-acyl to 3-acyl migration under the various conditions
used were followed by high performance liquid chromatography (HPLC). Optimum yields of the desired 1-alkyl-2-acyl-sn-glycerol (}90%) were obtained with a molar equivalent of boron trifluoride-methanol in methylene chloride at 22 C for five
min.
Presented in part at the AOCS meeting in Honolulu, Hawaii, in May 1986. 相似文献
This paper considers the quantum query complexity of almost all functions in the set \({\mathcal{F}}_{N,M}\) of \({N}\)-variable Boolean functions with on-set size \({M (1\le M \le 2^{N}/2)}\), where the on-set size is the number of inputs on which the function is true. The main result is that, for all functions in \({\mathcal{F}}_{N,M}\) except its polynomially small fraction, the quantum query complexity is \({ \Theta\left(\frac{\log{M}}{c + \log{N} - \log\log{M}} + \sqrt{N}\right)}\) for a constant \({c > 0}\). This is quite different from the quantum query complexity of the hardest function in \({\mathcal{F}}_{N,M}\): \({\Theta\left(\sqrt{N\frac{\log{M}}{c + \log{N} - \log\log{M}}} + \sqrt{N}\right)}\). In contrast, almost all functions in \({\mathcal{F}}_{N,M}\) have the same randomized query complexity \({\Theta(N)}\) as the hardest one, up to a constant factor. 相似文献