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51.
Dr Mitchell S. Golbus Joe Leigh Simpson Sarah E. Fowler Felix de la Cruz Robert J. Desnick Ronald Wapner David H. Ledbetter Herbert Lubs Maurice J. Mahoney Eugene Pergament George G. Rhoads Joseph D. Schulman Julia Zachary 《黑龙江环境通报》1992,12(5):373-376
Factors found to be associated with pregnancy loss after transcervical CVS were race (higher for non-white), history of spontaneous abortion, unplanned pregnancy, history of spotting or bleeding during the pregnancy prior to CVS, and placental position (higher for fundal or lateral locations). Whether the increase in loss risk is due to the factor, per se, or the factor plus the CVS cannot be determined due to the lack of appropriate control data. 相似文献
52.
Dr D. H. Ledbetter J. M. Zachary J. L. Simpson M. S. Golbus E. Pergament L. Jackson M. J. Mahoney R. J. Desnick J. Schulman K. L. Copeland Y. Verlinsky T. Yang-Feng S. A. Schonberg A. Babu A. Tharapel A. Dorfmann H. A. Lubs G. G. Rhoads S. E. Fowler F. De La Cruz 《黑龙江环境通报》1992,12(5):317-345
Cytogenetic data are presented for 11 473 chorionic villus sampling (CVS) procedures from nine centres in the U.S. NICHD collaborative study. A successful cytogenetic diagnosis was obtained in 99.7 per cent of cases, with data obtained from the direct method only (26 per cent), culture method only (42 per cent), or a combination of both (32 per cent). A total of 1.1 per cent of patients had a second CVS or amniocentesis procedure for reasons related to the cytogenetic diagnostic procedure, including laboratory failures (27 cases), maternal cell contamination (4 cases), or mosaic or ambiguous cytogenetic results (98 cases). There were no diagnostic errors involving trisomies for chromosomes 21, 18, and 13. For sex chromosome aneuploidies, one patient terminated her pregnancy on the basis of non-mosaic 47,XXX in the direct method prior to the availability of results from cultured cells. Subsequent analysis of the CVS cultures and fetal tissues showed only normal female cells. Other false-positive predictions involving non-mosaic aneuploidies (n = 13) were observed in the direct or culture method, but these cases involved rare aneuploidies: four cases of tetraploidy, two cases of trisomy 7, and one case each of trisomies 3, 8, 11, 15, 16,20, and 22. This indicates that rare aneuploidies observed in the direct or culture method should be subjected to follow-up by amniocentesis. Two cases of unbalanced structural abnormalities detected in the direct method were not confirmed in cultured CVS or amniotic fluid. In addition, one structural rearrangement was misinterpreted as unbalanced from the direct method, leading to pregnancy termination prior to results from cultured cells showing a balanced, inherited translocation. False-negative results (n = 8) were observed only in the direct method, including one non-mosaic fetal abnormality (trisomy 18) detected by the culture method and seven cases of fetal mosaicism (all detected by the culture method). Mosaicism was observed in 0.8 per cent of all cases, while pseudomosaicism (including single trisomic cells) was observed in 1.6 per cent of cases. Mosaicism was observed with equal frequency in the direct and culture methods, but was confirmed as fetal mosaicism more often in cases from the culture method (24 per cent) than in cases from the direct method (10 per cent). The overall rate of maternal cell contamination was 1.8 per cent for the culture method, but there was only one case of incorrect sex prediction due to complete maternal cell contamination which resulted in the birth of a normal male. The rate of maternal cell contamination was significantly higher in samples obtained by the transcervical sampling method (2. 16 per cent) than in samples obtained by the transabdominal method (0.79 per cent). From these data, it is clear that the culture method has a higher degree of diagnostic accuracy than the direct method, which should not be used as the sole diagnostic technique. The direct method can be a useful adjunct to the culture method, in which maternal cell contamination can lead to incorrect sex prediction and potentially to false-negative diagnostic results. 相似文献
53.
Christopher D. Klingshirn Zachary J. West Matthew J. DeWitt Ashil Higgins John Graham Edwin Corporan 《Journal of the Air & Waste Management Association (1995)》2019,69(8):1003-1013
The use of a two-step thermal-oxidative analysis (TOA) technique for quantification of the mass of total carbon (TC) and elemental carbon (EC) of turbine engine-borne particulate matter (PM) has been evaluated. This approach could be used in lieu of analysis methods which were developed to characterize diluted PM. This effort is of particular interest as turbine engine PM emissions typically have a higher EC content than ambient aerosols, and filter sample mass loadings can be significantly greater than recommended for existing analysis techniques. Analyses were performed under a pure oxygen environment using a two-step temperature profile; reference carbon and actual PM samples were used to identify appropriate analysis conditions. Thermal gravimetric analysis (TGA) methods were used to provide guidance on the nature of the carbon in several of the materials. This was necessary as a standard reference material does not exist for determination of the EC fraction in PM. The TGA also assisted in identifying an appropriate temperature range for the first-stage of the TOA method. Quantification of TC and EC for turbine engine PM samples using TOA was compared to results obtained using the NIOSH 5040 thermal-optical method. For first-stage TOA temperatures of 350°C and 400°C, excellent agreement between the techniques was observed in both the quantified TC and EC, supporting the viability for using TOA for analysis of turbine engine PM samples. A primary benefit of using TOA for these types of PM samples is that filters with relatively high PM mass loadings (sampled at the emission source) can be readily analyzed. In addition, an entire filter sample can be evaluated, as compared to the use of a filter punch sample for the NIOSH technique. While the feasibility of using a TOA method for engine PM samples has been demonstrated, future studies to estimate potential OC charring and oxidation of EC-type material may provide additional data to assess its impact on the OC/EC fractions for other carbon-type measurements.
Implications: This work presents results and procedures of an analytical method for the determination of total and elemental carbon, i.e., TC and EC present in combustion source particulate matter samples. In general, it is shown that the LECO TOA methodology is as reliable and comprehensive as NIOSH 5040 for determining TC and EC carbon types in particulate matter present in turbine emission sources, and should be considered as an alternative. Principles of the methodology, differences, and corresponding agreement with the standard NIOSH 5040 method and TGA analysis are discussed. 相似文献
54.
The feasibility of using composted civic waste for the remediation of a soil contaminated with petroleum hydrocarbons (extractable petroleum hydrocarbons (EPH) 10+/-1.8 g kg(-1) and total 16 USEPA PAH 1.62+/-0.5 g kg(-1)) was assessed. The effects of compost to soil ratio, in combination with and without earthworm presence (Dendrobaena veneta), upon the loss of contaminants were determined for EPH (GC-FID) and PAH (GC-MS), respectively. Increasing the ratio of compost substrate to hydrocarbon impacted soil (1:0.5, 1:1, 1:2 and 1:4 (soil:compost wt/wt)) in the absence of earthworms resulted in significantly (p<0.05) greater losses of both EPH and SigmaPAH after an 84 d incubation period, when compared to the soil only control. Where earthworms were present without compost, EPH losses were significantly (p<0.05) enhanced in the soil only treatment (33.4+/-5.3% residual) compared to the soil only control (54.4+/-5.3% residual). However, PAH loss in the soil only treatment (with-earthworm presence) were only slightly enhanced (65.3+/-9.3% residual), with respect to the soil only control (69.2+/-6.4% residual). Synergistic benefits of both earthworm and compost presence were most significant for PAHs (p<0.05), and less so for EPH. (14)C-respirometer studies, to establish catabolic competence in terms of microbial mineralisation of key hydrocarbons, complemented the hydrocarbon analysis. 相似文献
55.
Electron microscopic examination of thin-sectioned Limnoria tripunctata from creosoted and untreated wood substrates from Panama, Florida, and laboratory aquaria, coupled with limnorian behavioral studies revealed that bacteria may contribute to the wood boring, nutrition, and creosote-resistance of these isopods. Ingested along with wood fragments and encased in a peritrophic membrane in the isopod intestine, these bacteria, upon lysis, may provide supplemental nutrition to the nitrogen-poor wood diet of L. tripunctata. Ingested material has never been observed in the digestive diverticula of limnorians and the presence of the peritrophic membrane in the isopod intestine has been correlated with feeding. Isopods from creosoted wood differed from those inhabiting untreated wood in that the former contained relatively larger and more diverse bacterial populations both on their exoskeletons and in their gut contents. These isopods harbored bacteria, which apparently bypassed the peritrophic membrane and lived in association with the isopod intestinal lining. These gut-associated bacteria were lost when laboratory isopods reared on creosoted wood were transferred to untreated wood. Laboratory isopods reared solely on creosoted or untreated wood were exposed to creosoted and untreated wood substrates, both sterilized and unsterilized. Boring and mortality data from these studies indicated that the creosote-reared population had a microbial flora whose activity facilitated isopod colonization of creosoted substrates. We present the hypothesis that creosote hydrocarbons provide nutrition for isopod-associated bacterial populations and that L. tripunctata may benefit from a concomitant bacterial detoxification of the creosote. 相似文献
56.
Erin M.K. Haacker Vaishali Sharda Amanda M. Cano R. Aaron Hrozencik Agustín Núez Zachary Zambreski Soheil Nozari Garvey Engulu B. Smith Lacey Moore Sumit Sharma Prasanna Gowda Chittaranjan Ray Meagan Schipanski Reagan Waskom 《Journal of the American Water Resources Association》2019,55(1):6-23
Agricultural water management (AWM) is an interdisciplinary concern, cutting across traditional domains such as agronomy, climatology, geology, economics, and sociology. Each of these disciplines has developed numerous process‐based and empirical models for AWM. However, models that simulate all major hydrologic, water quality, and crop growth processes in agricultural systems are still lacking. As computers become more powerful, more researchers are choosing to integrate existing models to account for these major processes rather than building new cross‐disciplinary models. Model integration carries the hope that, as in a real system, the sum of the model will be greater than the parts. However, models based upon simplified and unrealistic assumptions of physical or empirical processes can generate misleading results which are not useful for informing policy. In this article, we use literature and case studies from the High Plains Aquifer and Southeastern United States regions to elucidate the challenges and opportunities associated with integrated modeling for AWM and recommend conditions in which to use integrated models. Additionally, we examine the potential contributions of integrated modeling to AWM — the actual practice of conserving water while maximizing productivity. Editor's note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series. 相似文献
57.
58.
59.
Zachary O. Toledo J. Boone. Kauffman 《Journal of the American Water Resources Association》2001,37(6):1653-1663
ABSTRACT: Intact riparian zones are the product of an incredibly complex multitude of linkages between the geomorphic, hydrologic, and biotiè features of the ecosystem. Land‐use activities that sever or alter these linkages result in ecosystem degradation. We examined the relationship between riparian vegetation and channel morphology by sampling species composition and herbaceous root biomass in incised (down‐cut and widened) versus unincised (intact) sections of unconstrained reaches in three headwater streams in northeastern Oregon. Incision resulted in a compositional shift from wetland‐obligate plant species to those adapted to drier environments. Root biomass was approximately two times greater in unincised sections than incised sections and decreased with depth more rapidly in incised sections than in unincised sections. Total root biomass ranged from 2,153 g m‐2 to 4,759 g m‐2 in unincised sections and from 1,107 g m‐2 to 2,215 g m‐2 in incised sections. In unincised sections less than 50 percent of the total root biomass was found in the top 10 cm, with approximately 20 percent in successive 10‐cm depth increments. In contrast, incised sections had greater than 60 percent of the total root biomass in the top 10 cm, approximately 15 percent in the 10 to 20 cm depth, less than 15 percent in the 20 to 30 cm depth, and less than 10 percent in the 30 to 40 cm depth. This distribution of root biomass suggests a positive feedback between vegetation and channel incision: as incision progresses, there is a loss of hydrologic connectivity, which causes a shift to a drier vegetation assemblage and decreased root structure, resulting in a reduced erosive resistance capacity in the lower zone of the streambank, thereby allowing further incision and widening. 相似文献
60.
Elizabeth A. Tibbetts Amanda Izzo Zachary Y. Huang 《Behavioral ecology and sociobiology》2011,65(5):1123-1131
Although there is increasing interest in the evolution of endocrine systems, relatively little is known about the factors
associated with natural endocrine variation in invertebrates. Here, we assess juvenile hormone (JH) titers among nest-founding
queens of the wasp Polistes dominulus over 2 years. We allowed unfamiliar wasps to battle for dominance and examined the relationships between dominance rank,
JH, ovarian development, and facial patterns. The relationship between JH-titer and dominance varied across years; there was
a stronger relationship between JH-titer and dominance in 2006 than in 2008. Across years, wasps that won dominance contests
had facial patterns with more broken black spots than wasps that lost dominance contests. There was no relationship between
dominance rank and ovarian development. The individual characteristics associated with JH-titer were also tested; JH-titers
were correlated with facial pattern brokenness and ovarian development. This study adds to previous work indicating that P. dominulus facial patterns function as a signal of fighting ability. Furthermore, the correlation between JH-titers and facial patterns
parallels previous work on testosterone and vertebrate signals and suggests that links between signals of fighting ability
and hormones that mediate fighting ability may be common across taxa. Overall, individual JH-titers vary, though they are
typically associated with factors related to individual reproductive success, including dominance, fertility, and facial pattern
brokenness. Future studies in additional contexts and taxa will be important to test how and why JH-titers vary. 相似文献