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61.
62.
Monika Schiesser Wolfgang Holzgreve Olav Lapaire Nils Willi Hans Lüthi Roberto Lopez Sevgi Tercanli 《黑龙江环境通报》2003,23(6):493-495
The sirenomelia sequence with fusion, rotation, hypotrophy or atrophy of the lower limbs in combination with severe urogenital and gastrointestinal malformations is a rare and usually lethal disorder. We present the case of a 28-year-old woman, who was referred to our department because of an intraabdominal cystic structure in the 9th week of gestation. Subsequent scans confirmed the diagnosis of a sirenomelia sequence with the fusion of the lower extremities without fusion of the bones according to Stocker I classification. The size of the intraabdominal cyst decreased during follow-up. After counseling, termination of pregnancy was induced. The postmortem X-ray confirmed the ultrasound diagnosis. The exact etiological mechanism of this malformation is still unknown. An early alteration of the embryological vascular network damaging the caudal mesoderm is thought to lead to arrested development of the lower limbs and other affected organs. The cyst we saw in the 9th week might fit with this theory, either as an expression of the complex malformation of the lower abdomen or as the sonographic appearance of necrosis. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Sokratis Papaspyrou Trine Gregersen Erik Kristensen Bjarne Christensen Raymond P. Cox 《Marine Biology》2006,148(3):541-550
The effects of infaunal mode of life on sediment properties, microbial reaction rates, as well as abundance and composition
of bacterial communities were studied in sediment surrounding burrows (mucus lining, oxidised wall, ambient anoxic and surface
sediment) of two closely related, but behaviourally different, nereidid polychaete worms: the facultative suspension-feeder
Nereis (Hediste) diversicolor and the obligate deposit-feeder Nereis (Neanthes) virens. Burrow sediment of the two species was collected from two adjacent (50 m distance) shallow sandy locations (Kertinge Nor,
Denmark). The burrow lining and wall of both polychaete species were enriched in organic matter originating from mucous secretions
by the inhabitants and phytoplankton trapped through irrigation. This was more evident for N. diversicolor that shows a significantly higher irrigation rate than N. virens. Both the organic matter mineralisation rates (based on anaerobic incubations) and bacterial abundance were higher along
the burrow linings and walls. However, accumulation of porewater TCO2 and dissolved organic carbon in sediments adjacent to burrows increased most rapidly in the presence of N. diversicolor, suggesting higher heterotrophic activity associated with this species. Surprisingly, bacterial abundance was lower around
burrows of N. diversicolor than those from N. virens indicating that burrow environments from the first species harbour a more active bacterial community. Molecular fingerprints
of the 16S rRNA gene from bacterial communities showed that the composition of the burrow linings and walls resembled the
ambient anoxic sediment rather than the oxic sediment surface. On the other hand, the bacterial fingerprints of the sediment
surrounding the burrows of the two polychaete species were markedly different suggesting either a site-specific difference
in sediment parameters or a significant species-specific impact of the burrow inhabitants. 相似文献
66.
The effect of different ambient sulphide concentrations on the internal pH regime of Hediste (Nereis) diversicolor was studied under in vivo conditions using liquid membrane pH microelectrodes, a method which is new to marine sciences.
As a case study, the hypothesis was tested whether organisms exposed to ambient sulphidic conditions are able to lower their
internal pH which, in effect, would reduce sulphide influx into the animals and thus could represent an effective detoxification
mechanism. It was shown that a significant lowering of the internal pH occurred within only 20 min after adding sulphide.
This pH lowering appeared to be dependent on the external sulphide concentration of the ambient medium and showed a saturation
beyond a threshold level of about 130 μM. It is discussed whether this sulphide-induced pH drop is an active regulatory mechanism
and acts as an effective protection mechanism against sulphide during short-term exposures.
Received: 1 June 1999 / Accepted in revised form: 3 May 2000 相似文献
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Holger Gulyas Pawel Choromanski Nils Muelling Maria Furmanska 《Journal of Cleaner Production》2009,17(13):1223-1227
Heterogeneous photocatalytic oxidation is a water reclamation technology which avoids chemical consumption and can be powered by solar radiation. Because this generally sustainable process is of limited efficiency for the treatment of biologically pretreated greywater, it was combined with activated carbon adsorption. The effluent of a constructed wetland for treatment of separately collected greywater was subjected to photocatalytic oxidation using the photocatalyst titanium dioxide (TiO2) “P25” in both the absence and the presence of powdered activated carbon (PAC). Photocatalytic oxidation alone with UV fluences of about 10 Wh L?1 was not capable of reducing total organic carbon (TOC) from an initial concentration of 5.5 mg L?1 safely below 2 mg L?1 as a prerequisite for high-quality water reuse purposes. However, when PAC was added, TOC concentrations subsequent to photocatalytic oxidation were less than 2 mg L?1 even after reusing the TiO2/PAC mixture 10 times. PAC addition is estimated to reduce the insolation area necessary to achieve this target by solar photocatalytic oxidation of biologically treated greywater by a factor 7. This combination process represents an innovative chemical-free technology within wastewater reuse schemes. 相似文献
69.
Ohlberger J Langangen Ø Edeline E Claessen D Winfield IJ Stenseth NC Vøllestad LA 《Ecology》2011,92(12):2175-2182
Recently developed theoretical models of stage-structured consumer-resource systems have shown that stage-specific biomass overcompensation can arise in response to increased mortality rates. We parameterized a stage-structured population model to simulate the effects of increased adult mortality caused by a pathogen outbreak in the perch (Perca fluviatilis) population of Windermere (UK) in 1976. The model predicts biomass overcompensation by juveniles in response to increased adult mortality due to a shift in food-dependent growth and reproduction rates. Considering cannibalism between life stages in the model reinforces this compensatory response due to the release from predation on juveniles at high mortality rates. These model predictions are matched by our analysis of a 60-year time series of scientific monitoring of Windermere perch, which shows that the pathogen outbreak induced a strong decrease in adult biomass and a corresponding increase in juvenile biomass. Age-specific adult fecundity and size at age were higher after than before the disease outbreak, suggesting that the pathogen-induced mortality released adult perch from competition, thereby increasing somatic and reproductive growth. Higher juvenile survival after the pathogen outbreak due to a release from cannibalism likely contributed to the observed biomass overcompensation. Our findings have general implications for predicting population- and community-level responses to increased size-selective mortality caused by exploitation or disease outbreaks. 相似文献
70.
Petter Næss Per Gunnar Røe Synnøve Larsen 《Journal of Environmental Planning and Management》1995,38(3):349-370
A study of the use of car and public transport among residents in 30 residential areas in Greater Oslo indicates that urban planning variables have a significant influence on the energy use per capita for local transport. Residents in local communities with a high density and a short distance to downtown Oslo travel considerably shorter distances and use considerably less energy per capita than those who live in low-density, outer areas. This is true also when the effects of other variables are neutralized. The influence of urban planning variables on the modal split is lower than on energy use. The distribution between public and private transport is influenced most of all by car ownership. 相似文献