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231.
232.
The stretching and break-up of tectonic plates by rifting control the evolution of continents and oceans, but the processes by which lithosphere deforms and accommodates strain during rifting remain enigmatic. Using scattering of teleseismic shear waves beneath rifted zones and adjacent areas in Southern California, we resolve the lithosphere-asthenosphere boundary and lithospheric thickness variations to directly constrain this deformation. Substantial and laterally abrupt lithospheric thinning beneath rifted regions suggests efficient strain localization. In the Salton Trough, either the mantle lithosphere has experienced more thinning than the crust, or large volumes of new lithosphere have been created. Lack of a systematic offset between surface and deep lithospheric deformation rules out simple shear along throughgoing unidirectional shallow-dipping shear zones, but is consistent with symmetric extension of the lithosphere. 相似文献
233.
M. Mereu J. F. Perez Olmos C. Fischer T. P. Mc Nally 《Equine Veterinary Education》2021,33(8):e286-e291
A 2-week-old 75 kg Thoroughbred filly was presented for the investigation of an acute forelimb lameness. Radiographs revealed a fracture of the medial epicondylar physis of the left humerus (Salter–Harris type II fracture). The fragment was removed via arthrotomy under general anaesthesia. Two months post-operatively, the foal was sound and at 2 years had resumed normal turn out. This case report describes a previously unreported surgical treatment for a fracture of the medial epicondylar physis in a foal. 相似文献
234.
Antonio Reverter Brad C Hine Laercio Porto-Neto Yutao Li Christian J Duff Sonja Dominik Aaron B Ingham 《Journal of animal science》2021,99(3)
In animal breeding and genetics, the ability to cope with disease, here defined as immune competence (IC), with minimal detriment to growth and fertility is a desired objective which addresses both animal production and welfare considerations. However, defining and objectively measuring IC phenotypes using testing methods which are practical to apply on-farm has been challenging. Based on previously described protocols, we measured both cell-mediated immune response (Cell-IR) and antibody-mediated immune response (Ab-IR) and combined these measures to determine an animal’s IC. Using a population of 2,853 Australian Angus steers and heifers, we compared 2 alternative methods to combine both metrics into a single phenotype to be used as a tool for the genetic improvement of IC. The first method, named ZMEAN, is obtained by taking the average of the individual metrics after subjecting each to a Z-score standardization. The second, ImmuneDEX (IDEX), is a weighted average that considers the correlation between Cell-IR and Ab-IR, as well as the difference in ranking of individuals by each metric, and uses these as weights in the averaging. Both simulation and real data were used to understand the behavior of ZMEAN and IDEX. To further ascertain the relationship between IDEX and other traits of economic importance, we evaluated a range of traits related to growth, feedlot performance, and carcass characteristics. We report estimates of heritability of 0.31 ± 0.06 for Cell-IR, 0.42 ± 0.06 for Ab-IR, 0.42 ± 0.06 for ZMEAN and 0.370 ± 0.06 for IDEX, as well as a unity genetic correlation (rg) between ZMEAN and IDEX. While a moderately positive rg was estimated between Cell-IR and Ab-IR (rg = 0.33 ± 0.12), strongly positive estimates were obtained between IDEX and Cell-IR (rg = 0.80 ± 0.05) and between IDEX and Ab-IR (rg = 0.85 ± 0.04). We obtained a moderately negative rg between IC traits and growth including an rg = −0.38 ± 0.14 between IDEX and weaning weight, and negligible with carcass fat measurements, including an rg = −0.03 ± 0.12 between IDEX and marbling. Given that breeding with a sole focus on production might inadvertently increase susceptibility to disease and associated antibiotic use, our analyses suggest that ImmuneDEX will provide a basis to breed animals that are both highly productive and with an enhanced ability to resist disease. 相似文献
235.
Removal of Heavy Metals from Soil Components and Soils by Natural Chelating Agents. Part II. Soil Extraction by Sugar Acids 总被引:1,自引:0,他引:1
Aqueous solutions of the natural chelatingagents D-gluconic acid and D-glucaric acid (D[+]-saccharic acid) were tested for their ability to remove heavy metals (Cd, Cr, Cu,Ni, Pb, Zn) from a soil polluted by long-term application of sewage sludge. Batch equilibrium experiments were performed undervariation of fundamental process parameters, i.e. pH value, sugaracid concentration, batch solution volume, solid:liquid ratioand number of treatment cycles.The extractability of heavy metals was low under near-neutral andslightly basic pH conditions. It increased drastically between pH12.0 and 13.0. Pb and Cu were preferentially extracted metals.Compared with the extraction efficiency of pH adequate puresodium hydroxide solutions, the sugar acids enhanced thesolubilisation of Pb and Cr especially. The metal depletion fromsoil was the highest when applying 20 or 50 g L-1 solutionsof the chelating agents. Under strongly basic conditions solid:liquid ratios of 1:10 or 1:20 were proofed to be advantageous.Except Ni, multi-step extraction improved the metal removalstrongly. This effect was the greatest for Cr extraction. Underoptimised conditions the following metal extraction degrees wereachieved with strongly alkaline D-gluconic acid solutions: Ni 43%%, Cr 60%%, Cd 63%%,Zn 70%%, Pb 80%%, and Cu 84%%. 相似文献
236.
Christof Braun J. Braschkat T. Mannheim Walter R. Fischer Horst Marschner 《植物养料与土壤学杂志》1994,157(4):265-269
Estimation of N2O-losses with a windtunnel - a comparison of methods No systematical investigations into the interactions between NH3-emissions and N2O-losses with different kinds of sludge applications have published so far. The use of a windtunnel, which is used for NH3-measurements, as a possible alternative method to measure N2O-emissions should be tested. Simultaneous measurements with open chambers and a windtunnel on a Catena in the country of Kraichgau (Baden-Württemberg) were done. Changing the construction of the windtunnel, it was possible to optimize the N2O-measurements and to eliminate constructional mistakes. But still the dilution factor is too big to take representative amounts of N2O. 相似文献
237.
Gabriel Billon Guy Thoumelin Jean-François Barthe Jean-Claude Fischer 《Journal of Soils and Sediments》2007,7(1):17-24
Background, Aim and Scope
The sulphidization process in relatively clean sediments sampled in a mudflat of the Authie estuary (located in Northern France)
has been studied by coupling geochemical expertise and the use of fatty acids (FAs) as biochemical markers.
Materials and Methods:
Three sediment cores have been sampled in September 2003, November 2003 and May 2004, and cut every 2 cm in the field under
nitrogen atmosphere so as to prevent any oxidation of reduced species. In the solid phase, reduced sulphur compounds, e.g.
AVS (Acid Volatile Sulphides) and CRS (Chromium Reducible Sulphur) [including also the calculation of the degree of sulphidization
(DOS) and the degree of pyritization (DOP)], and fatty acids have been carried out. Eh, pH, metal species (mostly iron and
manganese), dissolved S(-II) and sulphate have also been determined in the porewaters.
Results:
The sediment cores display a lot of differences due to the high sedimentation rate and the seasonal evolution as well. The
presence of Mn2+, Fe2+, S(-II) and the decrease of the redox potential and the concentration of sulphates clearly indicate
early diagenetic transformations promoted by the bacterial activity. Acid Volatile Sulphides are produced in the first cm
and are stabilized with depth. A rapid decrease of FAs concentrations in September and May has also been pointed out owing
to a rapid consumption of the labile organic matter. Several categories of FAs have been separated and most of them belong
here to the saturated and monounsaturated groups. In the saturated group, branched chain FAs, iso and anteiso C15:0 are predominant
and represent the bacterial imprint in the sediments. Maximum proportions are observed between 5 and 10 cm in September, and
between 13 and 17 cm in November and May.
Discussion:
As sulphate concentrations remain high in the porewater, the limitation of the sulphidization process in our sediments must
be due to a lack of labile organic matter input. The presence of pyrite in our sediment is bound to its formation at the water-sediment
interface, where partial reoxidation may take place. However, at deeper depths, pyritization processes does not continue any
more. Presence of maximum, dissolved S(-II) concentrations have been observed, simultaneously with maximum proportion relative
to total FAs of iso and anteiso C15:0, and, in September, with an increase in proportions of C18:1ω7. This indicates the presence
of sulphate-reducing bacterial activity at the time when the sediments were sampled. However, no close correspondence between
bacterial FAs concentrations and S(-II) concentrations has been found.
Conclusions:
In each core, the sulphidization process is not complete, and this is probably due to the lack of biodegradable organic matter,
which appears as the limiting factor from a qualitative point of view. S(-II) production in porewaters is linked with the
activity of sulphate-reducing bacteria. Seasonal effects have also been pointed out and, especially, a more important input
of diatom organic matter in May when compared to September and November.
Recommendations and Perspectives:
Fatty acid analyses represent an original and a useful tool for a better understanding of an early diagenetic process in the
first cm of the sediments. More studies should be carried out associating inorganic chemical parameters and chemical biomarkers
for pointing out stronger and more reproducible relations. Moreover, the use of microcosms in our group is on the way to take
into account the kinetics of the organic matter degradation during the early diagenesis. 相似文献
238.
Audun Korsaeth Philip Müller-Berghfer Konrad Mollenhauer Peter Fischer Martin Bach Hans-Georg Frede 《植物养料与土壤学杂志》1997,160(4):519-523
On the Effect of Organic Surface Cover on Lateral Transport of Isoproturon on Soil Surface The losses of the herbicide isoproturon with the surface runoff and the sediment loss have been measured by means of rainfall simulations on microplots (0.5 × 1 m2) with different mulch materials and increasing soil cover percentages (wheat straw vs. rape leafs). Soil cover by straw showed no significant effect on the runoff discharge, but the total loss of isoproturon increased between 22 and 37%. Soil cover by rape leafs diminished the runoff by between 13 and 61%, the reduction of isoproturon loss was in the same range. It was shown, that the different influences of different mulch materials on runoff and soil loss can lead to different pesticide losses. Therefore, the only giving of “mulch” without specification does not describe such experiments sufficiently. 相似文献
239.
W. R. Fischer 《植物养料与土壤学杂志》1984,147(4):449-455
Complexation of Cu, Pb, and Cd by water soluble humic substances I. The polarographic proof of heavy metal complexation by water soluble humic substances The complexation of Cu, Pb, and Cd by water soluble humic substances in aqueous solution decreases the peak height of differential pulse polarograms. Using the law of mass action with respect to definite complex formulae, empirical stability constants can be calculated, which are roughly independent from the presence of other cations. 相似文献
240.
Lizard distribution patterns in the Tumut fragmentation “Natural Experiment” in south-eastern Australia 总被引:1,自引:0,他引:1
Lizard distribution patterns were examined in a fragmented plantation landscape in south-eastern Australia. Regression modelling was used to relate ecological variables to (1) lizard species richness, (2) lizard species composition, and (3) the presence or abundance of selected lizard species. Ecological variables covered four broad domains that affect animals: climate, space, shelter and food availability.Lizard species richness was highest at mid-elevation sites, and at locations with a large amount of native forest within 1000 m. A major change in lizard species composition was associated with elevation, the proportion of native forest within 1000 m of a site, and the abundance of springtails. The change in species composition coincided with a range of individualistic responses to environmental conditions by different lizard species. For example, with respect to shelter availability, old logs were related to the garden skink Lampropholis guichenoti, shrubs were related to the delicate skink L. delicata, and rocks were related to the red-throated skink Bassiana platynota. The garden skink was most abundant at low elevations, the delicate skink was most likely to occur at intermediate elevations, and the mountain log skink Pseudemoia entrecasteauxii was most likely to occur at high elevations. The garden skink was most abundant in areas surrounded by little native forest, whereas Maccoy’s skink Nannoscincus maccoyi and Coventry’s skink Niveoscincus coventryi were more abundant or likely to occur in areas whose context was dominated by native forest.Because animal species may respond individualistically to gradients of climate, space, shelter and food availability, continuum theory (as developed for plant ecology) may be a useful complement to fragmentation theory to explain distribution patterns. To maintain lizard diversity in the study area, it will be important to maintain maximum habitat heterogeneity at the landscape and microhabitat scales. For species otherwise threatened by plantation development, large, fairly undisturbed areas of eucalypt forest will be particularly important. 相似文献