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41.
42.
R J Connor 《Biometrics》1987,43(1):207-211
Miettinen (1968, Biometrics 24, 339-352) presented an approximation for power and sample size for testing the differences between proportions in the matched-pair case. Duffy (1984, Biometrics 40, 1005-1015) gave the exact power for this case and showed that Miettinen's approximation tends to slightly overestimate the power or underestimate the sample size necessary for the design power. A simple alternative approximation that is more conservative is presented here. In many cases, the sample size for the independent-sample case provides a conservative approximation for the matched-pair design. 相似文献
43.
A total of 34 isolates ofListeria monocytogenes were tested against ampicillin, cephalothin, chloramphenicol, erythromycin, tetracycline, and penicillin-G using the Autobac 3-h AIS and the Autobac 5-h MIC procedures. The results were compared to susceptibility category interpretations and MICs determined using the Sceptor system. With the Sceptor System, all isolates were interpreted to be moderately susceptible to ampicillin and penicillin-G, and susceptible to the four other antibiotics. With the Autobac AIS, all isolates were interpreted to be susceptible to all the antibiotics except penicillin-G. All but one of the 34 isolates were interpreted to be resistant to penicillin-G with the Autobac AIS test. The remaining isolate was interpreted to be indeterminant. The Autobac AIS test was unsatisfactory for determining the susceptibility ofL. monocytogenes isolates to penicillin-G. The Autobac MIC results correlated well with the MIC results of the Sceptor system provided that the Autobac was programmed as though it were testing enterococci. The Autobac MIC reported penicillin-G MICs in units per milliliter and required the use of a conversion factor to obtain micrograms per milliliter, and did not allow for the testing of erythromycin. The Autobac MIC susceptibility category interpretations must not be used, as they were derived from an outdated susceptibility standard. The Autobac MIC test may be used if the limitations given above are observed. 相似文献
44.
Calcareous nannofossil stratigraphy has been investigated in Lower Cretaceous Italian sections at Gorgo a Cerbara, Presale and Frontale (all in the Umbrian Apennines) and at Cismon (Southern Alps). A modified sample preparation technique has allowed a thorough stratigraphic study of the well-lithified Maiolica limestone and although nannofossil preservation is generally quite poor, the major Valanginian to Aptian marker species can be detected. Nine nannofossil events can be determined and correlated to magnetic stratigraphies previously established in these sections. Nannofossil stratigraphy confirms most magnetostratigraphic correlations made between sections and allows a more precise correlation of magnetic Chrons M-0 to M-11 with the Valanginian, Hauterivian, Barremian and Aptian stages. The results obtained differ considerably from previous timescales. Nannofossil events recorded in the various sections may be time-transgressive by as much as one magnetic chron, probably due to differential preservation. 相似文献
45.
46.
Timothy J. Strabala Sebastian Y. Bednarek Gregory Bertoni Richard M. Amasino 《Molecular & general genetics : MGG》1989,216(2-3):388-394
Summary A 1.9 kb clone of the T-DNA region of the Agrobacterium tumefaciens Ti plasmid Bo542 which exhibited homology to the isopentenyl transferase (ipt) locus of pTiA6 was identified by low stringency DNA hybridization. Introduction of this segment of pTiBo542 DNA into cells of Nicotiana tabacum or N. glauca caused tumor formation in vivo, and allowed hormone independent growth in vitro. Furthermore, this DNA segment complemented ipt mutant strains of A. tumefaciens, restoring their ability to cause tumors on Kalanchöe leaves and tomato stems. The complete DNA sequence of this segment has been determined, revealing an open reading frame homologous to other known Agrobacterium ipt genes. 相似文献
47.
An important component of computer programs for determining the solution conformation of proteins and other flexible molecules
from nuclear magnetic resonance data are the so-called “bound smoothing algorithms”, which compute lower and upper limits
on the values of all the interatomic distances from the relatively sparse set which can usually be measured experimentally.
To date, the only methods efficient enough for use in large problems take account of only the triangle inequality, but an
appreciable improvement in the precision of the limits is possible if the algebraic relations between the distances among
each quadruple of atoms are also considered. The goal of this paper is to use a recently improved algorithm for computing
these “tetrangle inequality limits” to determine just how much improvement really is possible, given the types of experimental
data that are usually available. 相似文献
48.
Joe W. Dorner Richard J. Cole Timothy H. Sanders Paul D. Blankenship 《Mycopathologia》1989,105(2):117-128
Samples of Florunner peanuts were collected throughout a period of late-season drought stress with mean geocarposphere temperatures of 29 and 25 °C, and determinations of maturity, kernel water activity (aw), percent moisture, capacity for phytoalexin production, and aflatoxin contamination were made. Results showed an association between the loss of the capacity of kernels to produce phytoalexins and the appearance of aflatoxin contamination. Kernel aw appeared to be the most important factor controlling the capacity of kernels to produce phytoalexins. Mature peanuts possessed additional resistance to contamination that could not be attributed solely to phytoalexin production. Kernel moisture loss was accelerated in the 29 °C treatment compared to the 25 °C treatment, and data indicated that the higher soil temperature also favored growth and aflatoxin production by Aspergillus flavus in peanuts susceptible to contamination.Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. 相似文献
49.
Haplotype distribution of the human phenylalanine hydroxylase locus in Scotland and Switzerland. 总被引:13,自引:7,他引:6
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S E Sullivan S D Moore J M Connor M King F Cockburn B Steinmann R Gitzelmann S P Daiger S L Woo 《American journal of human genetics》1989,44(5):652-659
RFLP haplotypes at the phenylalanine hydroxylase (PAH) locus were determined in 45 nuclear Caucasian families from Switzerland and Scotland. The RFLPs at the PAH locus are highly informative, and prenatal diagnosis is possible in 85% of the families studied. The data were combined with the profiles previously observed in the Danish population, in order to study the variation in RFLP haplotype distribution among European populations. A total of 22 different haplotypes were observed in Denmark, Switzerland, and Scotland. Fifteen and 19 haplotypes are associated with the normal (non-PKU) and with the mutant chromosomes, respectively. The haplotype distribution and the allele frequency of normal chromosomes remain constant between Denmark, Switzerland, and Scotland. However, both the haplotype distribution and allele frequencies of mutant chromosomes show significant variation between the three countries. Our results suggest there may be additional mutations in the PAH gene that cause PKU. 相似文献
50.
This paper examines the physical consequences of increased catchment sediment yields on the sediment budget and the hydrodynamic setting of the South Johnstone River estuary in North Queensland. A combined study involving hydrological monitoring, assessment of sediment sources, estimation of riverine sediment budget and hydro-sedimentological numerical modelling for estuarine sediment transport is currently underway. Initial field and laboratory observations indicate that the sediment delivery from highly erosion-prone sugar cane cultivations in the tropical catchment has increased dramatically during the last 10 years. This has subsequently given rise to elevated flood levels in both the lower and upper catchment areas, as well as significant modifications to the river bed morphology. 相似文献