Development of a quick on‐farm test to determine nitrate levels in soil     

Urs Schmidhalter 《植物养料与土壤学杂志》2005,168(4):432-438

Crop management can be optimized and nitrogen (N) losses can be reduced with a better knowledge of soil‐nitrogen availability, especially if this information becomes directly available on‐site in a fast and cost‐effective way. In this paper, simple on‐farm methods to determine nitrate‐N in field‐moist soil samples immediately after sampling are described. The procedures include volumetric soil sampling, extraction based on manual shaking with tap water as universally available extractant, filtering soil/extractant mixtures on‐site, on‐site determination of the soil water content, and reflectometric nitrate measurements based on test strips. Using correction factors can compensate the impact of the temperature during the final nitrate measurement. An excellent agreement was found between the developed quick‐test procedures and the standard laboratory procedure. The proposed quick‐test has great potential to enable economical savings for farmers as well as benefiting the environment.  相似文献   

Air-coupled ultrasound as an accurate and reproducible method for bonding assessment of glued timber     

Sergio J. Sanabria  Christian Mueller  Juerg Neuenschwander  Peter Niemz  Urs Sennhauser 《Wood Science and Technology》2011,45(4):645-659

Glued timber products are widely used in construction; therefore, it is necessary to develop non-destructive bonding quality assessment methods for long-term structural health monitoring. Air-coupled ultrasound (ACU) inspection is a novel technique, with phenomenal improvements in reproducibility compared to traditional contact ultrasonics, unlimited scanning possibilities, and a high potential for delamination detection in wood products. As part of an ongoing project, glued timber samples of 10 mm thickness with artificial glue line defects were inspected. A normal through-transmission set-up with 120 kHz transducers allowed for successful and accurate imaging of the geometry of glued and non-glued areas in all inspected objects. The influence of wood heterogeneity and the reproducibility of ACU amplitude measurements were analysed in detail, identifying the main sources of variation. Future work is planned for the inspection of more complex glued timber objects.  相似文献   

Vaccine-Associated Immune-Mediated Hemolytic Anemia in the Dog   总被引：1，自引：0，他引：1  

Derek Duval  Urs Giger 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1996,10(5):290-295

Vaccination has been incriminated as a trigger of immune-mediated hemolytic anemia (IMHA) in dogs and in people, but evidence to support this association is lacking. In a controlled retrospective study, idiopathic IMHA was identified in 58 dogs over a 27–month period. When compared with a randomly selected control group of 70 dogs (presented for reasons other than IMHA) over the same period, the distribution of cases versus time since vaccination was different (P < .05). Fifteen of the dogs (26%) had been vaccinated within 1 month (mean, 13 days; median, 14 days; range, 1 to 27 days) of developing IMHA (P < .0001), whereas in the control group no marked increase in frequency of presentation was seen in the first month after vaccination. The dogs with IMHA were divided into 2 groups based on time since vaccination: the vaccine IMHA group included dogs vaccinated within 1 month of developing IMHA; the nonvaccine IMHA group included dogs that developed IMHA more than 1 month after vaccination. The recently vaccinated dogs with IMHA (vaccine IMHA group) had significantly lower platelet counts (P < .05) and a trend towards increased prevalence of intravascular hemolysis and autoagglutination when compared with the nonvaccine IMHA group. Similar mortality rates were seen in the vaccine IMHA group (60%) and the nonvaccine IMHA group (44%), with the majority of fatalities (>75%) occurring in the first 3 weeks after presentation. Persistent autoagglutination was a negative prognostic indicator for survival in both groups (P < .05). Presence of icterus and hyperbilirubinemia were negative prognostic indicators for survival in the nonvaccine IMHA group (P < .0001 and P < .01, respectively) but not in the vaccine IMHA group. In the recently vaccinated dogs, combination vaccines from various manufacturers against canine distemper, adenovirus type 2, leptospirosis, parainfluenza, and parvovirus (DHLPP) were involved in each case. Vaccines against rabies virus, Bordetella spp, coronavirus, and Lyme Borrelia were administered concomitantly to some dogs. This study provides the first clinical evidence for a temporal relationship of vaccine-associated IMHA in the dog.  相似文献   

A kinetic framework for a mammalian RNA polymerase in vivo     

Dundr M  Hoffmann-Rohrer U  Hu Q  Grummt I  Rothblum LI  Phair RD  Misteli T 《Science (New York, N.Y.)》2002,298(5598):1623-1626

We have analyzed the kinetics of assembly and elongation of the mammalian RNA polymerase I complex on endogenous ribosomal genes in the nuclei of living cells with the use of in vivo microscopy. We show that components of the RNA polymerase I machinery are brought to ribosomal genes as distinct subunits and that assembly occurs via metastable intermediates. With the use of computational modeling of imaging data, we have determined the in vivo elongation time of the polymerase, and measurements of recruitment and incorporation frequencies show that incorporation of components into the assembling polymerase is inefficient. Our data provide a kinetic and mechanistic framework for the function of a mammalian RNA polymerase in living cells.  相似文献   

Soil fertility and biodiversity in organic farming   总被引：11，自引：0，他引：11  

Mäder P  Fliessbach A  Dubois D  Gunst L  Fried P  Niggli U 《Science (New York, N.Y.)》2002,296(5573):1694-1697

An understanding of agroecosystems is key to determining effective farming systems. Here we report results from a 21-year study of agronomic and ecological performance of biodynamic, bioorganic, and conventional farming systems in Central Europe. We found crop yields to be 20% lower in the organic systems, although input of fertilizer and energy was reduced by 34 to 53% and pesticide input by 97%. Enhanced soil fertility and higher biodiversity found in organic plots may render these systems less dependent on external inputs.  相似文献   

Rangeland Ecosystem Goods and Services: Values and Evaluation of Opportunities for Ranchers and Land Managers     

Kristie Maczko  John A. Tanaka  Robert Breckenridge  Lori Hidinger  H. Theodore Heintz  William E. Fox  Urs P. Kreuter  Clifford S. Duke  John E. Mitchell  Daniel W. McCollum 《Herpetological Monographs》2011,33(5):30-36

  相似文献   

The neural basis of altruistic punishment   总被引：2，自引：0，他引：2  

de Quervain DJ  Fischbacher U  Treyer V  Schellhammer M  Schnyder U  Buck A  Fehr E 《Science (New York, N.Y.)》2004,305(5688):1254-1258

Many people voluntarily incur costs to punish violations of social norms. Evolutionary models and empirical evidence indicate that such altruistic punishment has been a decisive force in the evolution of human cooperation. We used H2 15O positron emission tomography to examine the neural basis for altruistic punishment of defectors in an economic exchange. Subjects could punish defection either symbolically or effectively. Symbolic punishment did not reduce the defector's economic payoff, whereas effective punishment did reduce the payoff. We scanned the subjects' brains while they learned about the defector's abuse of trust and determined the punishment. Effective punishment, as compared with symbolic punishment, activated the dorsal striatum, which has been implicated in the processing of rewards that accrue as a result of goal-directed actions. Moreover, subjects with stronger activations in the dorsal striatum were willing to incur greater costs in order to punish. Our findings support the hypothesis that people derive satisfaction from punishing norm violations and that the activation in the dorsal striatum reflects the anticipated satisfaction from punishing defectors.  相似文献   

Requirement of JNK2 for scavenger receptor A-mediated foam cell formation in atherogenesis   总被引：1，自引：0，他引：1  

Ricci R  Sumara G  Sumara I  Rozenberg I  Kurrer M  Akhmedov A  Hersberger M  Eriksson U  Eberli FR  Becher B  Borén J  Chen M  Cybulsky MI  Moore KJ  Freeman MW  Wagner EF  Matter CM  Lüscher TF 《Science (New York, N.Y.)》2004,306(5701):1558-1561

In vitro studies suggest a role for c-Jun N-terminal kinases (JNKs) in proatherogenic cellular processes. We show that atherosclerosis-prone ApoE-/- mice simultaneously lacking JNK2 (ApoE-/- JNK2-/- mice), but not ApoE-/- JNK1-/- mice, developed less atherosclerosis than do ApoE-/- mice. Pharmacological inhibition of JNK activity efficiently reduced plaque formation. Macrophages lacking JNK2 displayed suppressed foam cell formation caused by defective uptake and degradation of modified lipoproteins and showed increased amounts of the modified lipoprotein-binding and -internalizing scavenger receptor A (SR-A), whose phosphorylation was markedly decreased. Macrophage-restricted deletion of JNK2 was sufficient to decrease atherogenesis. Thus, JNK2-dependent phosphorylation of SR-A promotes uptake of lipids in macrophages, thereby regulating foam cell formation, a critical step in atherogenesis.  相似文献   

Serodiagnosis and monitoring of contagious bovine pleuropneumonia (CBPP) with an indirect ELISA based on the specific lipoprotein LppQ of Mycoplasma mycoides subsp. mycoides SC.     

Urs Bruderer  Jose Regalla  El-Mostafa Abdo  Otto J B Huebschle  Joachim Frey 《Veterinary microbiology》2002,84(3):195-205

An indirect ELISA, based on the specific and strongly antigenic recombinant peptide of the N'-terminal half of the lipoprotein LppQ from Mycoplasma mycoides subsp. mycoides small colony type (SC) was developed for the detection of antibodies to M. mycoides subsp. mycoides SC. It was evaluated for its suitability for serodiagnosis and monitoring of contagious bovine pleuropneumonia (CBPP). The recombinant peptide containing poly-histidine residue tails was expressed in Escherichia coli and subsequently purified by Ni(2+) chelate affinity chromatography to be used as antigen to coat microtiter ELISA plates. The specificity of the antigen was tested against rabbit hyperimmune sera directed against related Mycoplasmas of the M. mycoides cluster and with sera from cattle that were either free of CBPP, but suffered from other mycoplasmal infections such as M. bovis, or showed cross-reactions in the complement fixation test. The sensitivity of the ELISA was assessed with sera from artificially infected animals and with sera from cattle originating from areas where CBPP was endemic at the time of blood sampling. The study revealed that the ELISA was both specific and sensitive for CBPP positive bovine sera and was shown also to be robust to harsh climatic conditions.  相似文献   

Cadmium Stress in Barley: Growth,Leaf Pigment,and Protein Composition and Detoxification of Reactive Oxygen Species     

Klimentina Demirevska-Kepova  Lyudmila Simova-Stoilova  Zlatimira Petrova Stoyanova  Urs Feller 《Journal of plant nutrition》2013,36(3):451-468

Barley seedlings (Hordeum vulgare L., cv. ‘Obzor’) were exposed for 5 d to 0, 5, 50, and 500 μM CdCl₂ in nutrient solution. Cadmium (Cd) treatment caused a reduction of plant length, biomass, and leaf pigment content. The level of soluble leaf proteins was not changed significantly. SDS-PAGE revealed a slight diminution of Rubisco subunits and the appearance of a new low molecular mass band after exposure to 50 or 500 μM Cd. The antioxidative protection in leaves under Cd toxicity was studied in its complexity. Slightly diminished superoxide dismutase, enhanced catalase, and drastically increased total peroxidase activities were found at the highest Cd level. Ascorbate peroxidase activity was not changed significantly. The isoenzyme patterns of the antioxidant enzymes under study were only slightly altered without synthesis of new isoforms. The content of oxidized ascorbate increased during exposure to 50 and 500 μM Cd. The level of H₂O₂ rose only at 500 μM Cd without accumulation of malondialdehyde and oxidized proteins. Non-protein thiol groups increased up to four-fold after exposure to 50 and 500 μM Cd. The results are in accordance with the induction of mechanisms allowing an immobilization and sequestration of Cd in barley leaves, and suggest only minor effects via oxidative damage.  相似文献