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181.
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183.
PD Dr Ingo Kennerknecht Gotthold Barbi Michael Wolf Mahmoud Djalali Dieter Grab Rainer Terinde Walther Vogel 《黑龙江环境通报》1993,13(10):929-944
An increasing number of cytogenetic prenatal diagnoses are performed on chorionic villus samplings. The accuracy of this method is influenced by chromosomal mosaicism, mostly confined to direct preparation methods. Especially those investigators who have experienced false-negative and false-positive findings propagate the combined use of direct and culture methods. Yet large collaborative studies have shown that in approximately two-thirds of diagnostic cases only one procedure is applied. Moreover, the accuracy of a cytogenetic investigation depends not only on the ontogenetic origin of the tissues investigated, but also on interacting factors such as the ‘a priori risk’ and the ‘predictive value of a cytogenetic finding’. On this basis a differentiated prenatal diagnostic procedure is discussed, including either sole short-term culture (STC), combined STC and long-term culture (LTC), primary amniocentesis (AC), or primary percutaneous umbilical blood sampling (PUBS). The predictive value of the cytogenetic diagnosis from CVS varies significantly dependent on the a priori risk of a chromosome aberration and, in the case of an abnormal karyotype, on the specific chromosome involved. A non-mosaic and ‘non-lethal’ trisomy detected in STC is highly representative of the embryo/fetus, but there are exceptions of limited predictive value, e.g., trisomy 18. Guided by the strategy of an optional follow-up by LTC, AC, or PUBS in 1317 successive CV samplings, we are not aware of a false-negative diagnosis, but probably had one false-positive diagnosis: 47,XXY after STC; 46,XY after LTC. When referring to the rate of fetuses with an unbalanced karyotype expected in the different indication groups, a relative increase of false-positive findings in the very-low-risk group (maternal age ⩽35 years of age) and of false-negative findings in the very-high-risk group (abnormal ultrasonographic findings) of pregnant women when only performing CVS becomes obvious. Because of this dilemma, AC or—especially in the latter group—PUBS might be primarily offered to these indication groups instead of CVS. 相似文献
184.
Rosen Johannes Fichtner Wolf Rentz Otto 《Mitigation and Adaptation Strategies for Global Change》2004,9(2):121-146
Determining adequate baselinesis a major methodological problem whenquantifying emissions reductions achievedwith the project-based flexibilitymechanisms. Possible methodologies forbaseline setting may be classified intomulti-project and project-specificapproaches. While multi-project approachesprovide baselines for a series of typicalprojects within a certain geographicregion, a sector, or a load range,project-specific (orproject-by-project/single-project)approaches only cover one specific project.Project-by-project baseline approaches havebeen tested extensively within theActivities Implemented Jointly (AIJ) pilotphase; multi-project methodologies, on theother hand, have only rarely been applieddue to the (perceived) political andeconomic complexity of the issue, whichmakes the process of introducingstandardised baselines a very sensitivetask. In particular, there is a lack ofmulti-project baseline approaches takingadvantage of optimising computer modelswithin the electricity sector, even thoughother fields of research have made use ofsuch models quite successfully in the past.Experiences made in the PROBASE projectwith the calculation of standardised,aggregated multi-project baselines forJI/CDM projects using optimising energysystem models are illustrated in this paperfor South Africa, Russia, and Indonesia.Increased transparency and credibility ofstandardised approaches along withpotentially lower transaction costs areidentified as the main arguments for theiruse and further development. In addition,the text gives recommendations wheremodel-based baseline standardisation canpreferentially be applied. 相似文献
185.
Wolf von Tümpling Peter Zeilhofer Ulrich Ammer Jürgen Einax Rolf -D. Wilken 《Environmental science and pollution research international》1995,2(4):225-228
As in many other parts of the world, gold is produced in the surface mining region of Poconé, Mato Grosso, Brazil, using mercury.
The goal of this investigation was to estimate the amount of mercury in certain tailings and to determine the area of the
land that has been contaminated by the gold mining operations. Mercury concentrations from 2 to 495 ng/g (dw) were determined
in the tailing materials. It was observed that only isolated sites were acting as central points of contamination. Using digital
Landsat satellite data (The-matic Mapper) and aerial photos, the sites degraded by the mining were classified, and their total
area was estimated to be 12.3 km2 in the region of Poconé. It was estimated, that 4.9 km2 were occupied by the contaminated tailings. The mean height of the pile slags was determined to be 4.5 m. From the experimentally
calculated average density of the material in the tailings, 2.01 g/cm3, the total mercury content in the piles of tailings was estimated to be 1600 ± 350 kg. 相似文献
186.
Karl-Werner Schramm Petra Marth Alexander Wolf Klaus Hahn Konstantin Oxynos Johannes Schmitzer und Antonius Kettrup 《Umweltwissenschaften und Schadstoff-Forschung》1999,11(5):277-280
Zusammenfassung Lipidbezogene Verteilungskoeffizienten (KLM/L) zwischen Muskelkonzentrationen-(CML) und Leberkonzentrationen (CLL) zweier Friedfischarten Brassen (Abramis brama) und Aalmutter (Zoarces viviparus) ergeben theoriekonform (KLM/L=CML/CLL=1) nominale Werte um 1 für persistente (hochchlorierte PCB) und Werte über 1 für metabolisierbare lipophile Umweltchemikalien
wie chlorierte Cyclohexane oder DDT.
相似文献
187.
188.
Jochen B. W. Wolf Göran Kauermann Fritz Trillmich 《Behavioral ecology and sociobiology》2005,59(2):293-302
In many sexually dimorphic species adult sexes tend to segregate socially, spatially, or in habitat use. Several hypotheses have been formulated regarding underlying mechanisms. We investigated terrestrial habitat use and sexual segregation in a tropical otariid, the Galápagos sea lion (Zalophus californianus wollebaeki), where most of the hypotheses can be ruled out a priori. Factors relating to thermoregulation and costs of locomotion were of prime importance for habitat use. Habitats directly adjacent to the sea, with simple structured flat surfaces, shade, and tide pools were most frequented, but sexes and age classes differed in their usage patterns. Sexual segregation, both spatial and by habitat was pronounced in the reproductive period (RP), but remained high during the nonreproductive period (NRP). A GLM model of habitat use showed that in both seasons adult males frequented habitat types that adult females and other age classes used much less. Males were most abundant in suboptimal inland habitats, which offered only shade for cooling. Females with newborns differed in habitat use from females with older offspring and lone females. Spatial and habitat segregation are explained most parsimoniously as by-products of social processes, primarily intrasexual competition and female avoidance of male harassment, linked to the polygynous mating system.Electronic Supplementary Material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
189.
Georgios Tsounis Sergio Rossi Maria Aranguren Josep-Maria Gili Wolf Arntz 《Marine Biology》2006,148(3):513-527
Red coral (Corallium rubrum, L. 1758) is an over-exploited Mediterranean gorgonian. The gonadal development cycle of this gorgonian is examined at the
Costa Brava (NW Mediterranean) taking into account for the first time colony size, depth and spatial horizontal variability.
This study compares the gonad development and fertility in two colony size classes (colonies <6-cm height, and >10-cm height,
both at 40–45-m depth), and two populations at different depths (16–18-m depth, and 40–45-m depth, both consisting of <6-cm
high colonies) in a 15-month period. The fertility of seven size classes (<2 cm to >12 cm high colonies, in 2 cm intervals)
was examined in the deep population, where large colonies were present. Furthermore, reproductive output was compared in 6
populations (distributed along more than 70-km coastline) one month before spawning (June). Red coral was found to be dioecious
and gonochoric with a sex ratio of 1:1, which differs from other NW Mediterranean populations. On the other hand, fertility
of different size classes indicates that small colonies of 2-cm height already produce gonads, which is in line with previous
studies. Female and male polyp fertility and sperm sac size increase significantly with colony size [sperm sac diameter: 476±144 μm
(mean±SD) and 305±150 μm in the >10-cm and <6-cm height colonies, respectively), whereas no significant effect on oocyte diameter
was found (oocyte diameter: 373.7±18.7 μm). Depth staggered spawning, that is, an earlier release of gonads in the shallow
populations, was observed in summer 2003, coinciding with the highest temperature gradient between shallow and deep water
during the study period. Colonies of <6-cm height were significantly less fertile than colonies >12 cm, thus the recommendation
of this study is that a minimum height should be incorporated into fishing regulations. The six studied populations at the
Costa Brava showed a comparable reproductive potential, which demonstrates little variability within the homogenous population
structure and range of size classes (due to overharvesting) found at the Costa Brava. The study of reproductive output is
an important tool for ecosystem management, and this work recommends basing specific exploitation laws for distinctive populations
on colony size, which is found to have a larger effect on reproductive potential than mesoscale variability.
An erratum to this article can be found at 相似文献
190.