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31.
The spatial variability in the mineralisation rate of linuron [N-(3,4-dichlorophenyl)-N'-methoxy-N'-methylurea] was studied within a previously treated Danish agricultural field by sampling soils from eleven different plots randomly distributed across an area of 20 x 20 m. The soils were characterised with respect to different abiotic and biotic properties including moisture content, organic matter content, pH, nutrient content, bacterial biomass, potential for mineralisation of MCPA [(4-chloro-2-methylphenoxy)acetic acid] and linuron. Five soils had a potential for mineralisation of linuron, with 5-15% of the added [ring-U-14C]linuron metabolised to 14CO2 within 60 days at 10 degrees C, while no extensive mineralisation of linuron was observed in the six remaining soils within this period. A TLC analysis of the methanol-extractable residues showed no development of 14C-labelled metabolites from linuron in any of the samples. Multivariate analysis was conducted to elucidate relationships between the intrinsic properties of single soil samples and initial rate of linuron mineralisation. The analysis indicated that important soil parameters in determining the spatial heterogeneity included the C(total)/N(total) ratio, pH and the water-extractable potassium contents, with the first of these highly negatively correlated and the last two highly positively correlated to the initial linuron mineralisation rate. This study shows that enhanced biodegradation of linuron may develop with successive field treatments, but that considerable in-field spatial heterogeneity in the degradation rate still exists. Combined with a parallel enrichment study focused on the underlying microbial processes, the present results suggest that intrinsic soil properties affect the linuron-metabolising bacterial population and thereby determine the spatial variability in the linuron mineralisation activity.  相似文献   
32.
Funisitis associated with leptospiral abortion in an equine placenta   总被引:1,自引:0,他引:1  
Funisitis, inflammation of the umbilical cord, is well recognized in human placentas. This report describes a case of funisitis associated with leptospiral infection in the placenta of a Thoroughbred foal born prematurely. The umbilical cord had diffuse superficial yellow discoloration along its entire length. Microscopic evaluation showed an exudate of neutrophils admixed with fibrin on the surface. Warthin-Starry staining showed spirochetes in the Wharton's jelly of the umbilical cord. A locally extensive, severe placentitis not involving the star and allantoic cystic hyperplasia were the other lesions observed in the allantochorion. Leptospira funisitis is similar to the funisitis of congenital syphilis in humans, although there are some major microscopic differences. In Leptospira funisitis, lesions were limited to the cord surface, whereas in lesions in human umbilical cords with Treponema pallidum infection, the changes are observed mostly around the vessels and in the Wharton's jelly.  相似文献   
33.
PCV-2 is involved in "postweaning multisystemic wasting syndrome" (PMWS), "porcine dermatitis and nephropathy syndrome" (PDNS), respiratory and reproductive disorders, and thereby plays a crucial role in today's swine production world-wide. The virus is apparently ubiquitous in domestic pigs and has also been demonstrated in wild pigs. Up to now, a characterization of PCV-2 samples from wild pigs, which might help to estimate the possible role of wild pigs as sources of domestic pig infection, has not been carried out. Spleen samples from 16 PCV-2-positive wild pigs from hunting grounds of four regions in Germany were used for the analysis of the viral genome. In one sample, the complete sequence of the genome was determined. In the other, a 742 nucleotide fragment from the highly variable capsid sequence of the ORF2 was sequenced. Analysis of the sequences led to the identification of three PCV-2 strains. One strain, representing 14 of the 16 samples, was closely related with Chinese, but not with German strains. The genome of this strain was shortened by one nucleotide by a deletion close to the end of ORF2. The deletion led to a shift of the stop-codon and to the insertion of a further codon. Two further strains differed in up to 4.7% of nucleotides and up to 10.5% of amino acids (aa). These strains were aligned with clusters of PCV-2 samples from mainly French and German domestic origin.  相似文献   
34.
Renewed interest in plant-derived drugs has led to an increased need for efficient extraction methods. Hypericum perforatum L. contains several groups of bioactive compounds with noteworthy pharmacological activities. Direct sonication of H. perforatum was investigated and compared with conventional maceration, indirect sonication, Soxhlet extraction, and accelerated solvent extraction (ASE). Highly selective liquid chromatography/tandem mass spectrometry analysis showed that the content of six investigated active compounds (hypericin, pseudohypericin, hyperoside, rutin, quercitrin, and hyperforin) in extracts obtained by direct sonication was significantly higher than in extracts obtained by the other methods. The active compound contents increased on increasing the ultrasonic power from 40 to 60 W when using direct sonication. Conventional maceration gave the lowest amount of analyzed active compounds. Soxhlet extraction gave better results than ASE or indirect sonication.  相似文献   
35.
Intraperitoneal administration of ICSM18 and 35, monoclonal antibodies against prion protein (PrP), has been shown to significantly delay the onset of prion disease in mice, and humanized versions are candidate therapeutics for prion and Alzheimer's diseases. However, a previous report of severe and widespread apoptosis after intracerebral injection of anti-PrP monoclonal antibodies raised concerns about such therapy and led to an influential model of prion neurotoxicity via cross-linking of cell surface PrP by disease-related PrP aggregates. In extensive studies including ICSM18 and 35, fully humanized ICSM18, and the previously reported proapoptotic antibodies, we found no evidence of apoptosis, thereby questioning this model of prion neurotoxicity.  相似文献   
36.
Life-span theories explain successful aging with an adaptive management of emotional experiences like regret. As opportunities to undo regrettable situations decline with age, a reduced engagement into these situations represents a potentially protective strategy to maintain well-being in older age. Yet, little is known about the underlying neurobiological mechanisms supporting this claim. We used a multimodal psychophysiological approach in combination with a sequential risk-taking task that induces the feeling of regret and investigated young as well as emotionally successfully and unsuccessfully (i.e., late-life depressed) aged participants. Responsiveness to regret was specifically reduced in successful aging paralleled by autonomic and frontostriatal characteristics indicating adaptive shifts in emotion regulation. Our results suggest that disengagement from regret reflects a critical resilience factor for emotional health in older age.  相似文献   
37.
Due to high variation in forest communities, forest structure and the fragmentation of the forested area in Central Europe, satellite-based forest inventory methods have to meet particularly high-quality requirements. This study presents an innovative method to combine official forest inventory information at stand level with multidate satellite imagery using a spatially adaptive classification approach for producing wall-to-wall forest cover maps of important tree species and management classes across multiple ownership regions in a heterogeneous low mountain range in Germany. The classification approach was applied to a 5,200-km2 area (about 2,080?km2 of forest land, mostly mixed forests) located in the Eifel mountain range in Central Europe. In comparison with conventional classifiers, our results demonstrate a significant increase in classification accuracy in the order of 12%. The method was tested with ASTER images but holds the potential to be used for regular state forest inventories based on standard and novel earth observation data supplied for instance from the SPOT-5 and RapidEye sensors.  相似文献   
38.
The objective of the present research was to determine the effect of increasing and decreasing natural photoperiods on selected parameters of boar ejaculates. The study material consisted of 17 boars: six Polish Large White (PLW) breed, five Polish Landrace (PL) breed, and six Duroc×Pietrain (D×P) crossbreed, all aged between 8 and 12 months at the beginning of the research. Analyses were conducted on 612 ejaculates, which were collected in two experimental periods: an increasing photoperiod (IP) (January–June) and a decreasing photoperiod (DP) (July–December). A statistically proven impact of photoperiod on the volume of semen was observed in all the studied breeds (P=0.004). During the decreasing photoperiod the mean volume of semen was 261.16±75.20 ml and this was almost 17 ml higher than that for the increasing period. For boars involved in the experiment, day length also had a significant impact on the total number of motile spermatozoa (P=0.037). In the increasing photoperiod the mean number was 3.26×109 lower. A decreasing photoperiod has a positive affect on both boars and the parameters of the collected ejaculates, which were observed in the higher number of insemination doses per ejaculate. Between the different breeds, the reactions of boars to photoperiod differed and the most significant influence of photoperiod on semen parameters was noted among D×P breed boars. Least susceptible to changes in day length were PLW breed boars.  相似文献   
39.
China's government aims to become an innovation nation and promotes the development of so-called indigenous innovation. Under this paradigm of state-encouraged innovation, however, it is unclear how domestic firms organize their innovation processes. We distinguish between two strategies in that respect: closed versus open innovation. Our findings suggest that firms with closed innovation processes collaborate in close geographic distance, rely on DUI-modes of learning, and collaborations are based on guanxi. In contrast, firms with open innovation processes collaborate over large distances and rely on STI-modes of learning that are not necessarily guanxi-based. The findings help to understand the heterogeneous nature of indigenous innovation in China.  相似文献   
40.
Andersson  Erik  Haase  Dagmar  Scheuer  Sebastian  Wellmann  Thilo 《Landscape Ecology》2020,35(7):1605-1618
Landscape Ecology - Urban densification has been argued to increase the contrast between built up and open green space. This contrast may offer a starting point for assessing the extent and...  相似文献   
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