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131.
Uwe Greggers Caspar Schöning Jacqueline Degen Randolf Menzel 《Die Naturwissenschaften》2013,100(8):805-809
Harmonic radar tracking was used to record the flights of scout bees during takeoff and initial flight path of two honeybee swarms. One swarm remained intact and performed a full flight to a destination beyond the range of the harmonic radar, while a second swarm disintegrated within the range of the radar and most of the bees returned to the queen. The initial stretch of the full flight is characterized by accelerating speed, whereas the disintegrating swarm flew steadily at low speed. The two scouts in the swarm displaying full flight performed characteristic flight maneuvers. They flew at high speed when traveling in the direction of their destination and slowed down or returned over short stretches at low speed. Scouts in the disintegrating swarm did not exhibit the same kind of characteristic flight performance. Our data support the streaker bee hypothesis proposing that scout bees guide the swarm by traveling at high speed in the direction of the new nest site for short stretches of flight and slowing down when reversing flight direction. 相似文献
132.
Christina Jarke Anja Petereit Karsten Fehlhaber Peggy G. Braun Uwe Truyen Thiemo Albert 《Food and environmental virology》2013,5(3):135-143
Until now, little is known about the influence of food additives on heat inactivation of noroviruses. Only a few studies have shown a protective or inhibiting effect on virus infectivity caused by the food matrix. Therefore, the aim of this study was to examine the influence of sodium chloride, sucrose and milk on heat stability of the surrogates murine norovirus (MNV) and MS2 phage at 60 °C for 1–5 min in PBS for MNV and for 5–120 min in suspension medium buffer for MS2 phage. Different concentrations of sodium chloride (5, 10 %) and sucrose (5, 50 %) were added to the respective buffers. In addition, commercially available milk with different fat concentrations (0.3, 1.5, 3.5 %) was investigated in this study. In general, a linear titre reduction for MNV and MS2 phage could be observed, except for the heat treatment of MNV in PBS with 50 % sucrose. A protective effect of PBS with 50 % sucrose and of the matrix milk on MNV could be concluded. All other tested conditions did not show any influence on virus inactivation. However, MS2 phage did show a higher heat resistance throughout the experiments compared to MNV. In future investigations, it should be tested, whether the achieved data may be considered in risk assessments of heat-treated food products with high concentrations of sugar. Furthermore, it should be clarified, whether these results can also be referred to complex food matrices. 相似文献
133.
Leakage and Comparative Advantage Implications of Agricultural Participation in Greenhouse Gas Emission Mitigation 总被引:2,自引:0,他引:2
Heng-Chi Lee Bruce A. McCarl Uwe A. Schneider Chi-Chung Chen 《Mitigation and Adaptation Strategies for Global Change》2007,12(4):471-494
The world is moving toward efforts to reduce net greenhouse gas emissions. Reduction efforts may involve the agricultural
sector through options such as planting of trees, altering crop and livestock management, and increasing production of biofuels.
However, such options can be competitive with domestic food production. In a free trade arena, reduced domestic food production
could stimulate increased production and exports in other countries, which are not pursuing net emission reductions. As a
consequence, emission reduction efforts in implementing countries may be offset by production increases stimulated in other
countries.
We examine the competitive effects of agriculturally related emission reduction actions on agricultural production and international
trade. In doing this, we employ the assumption that U.S. emission reduction caused cost increases will also occur in other
reducing countries. We consider emission reduction: 1) unilaterally by the U.S., 2) by all Kyoto Protocol Annex B countries,
and 3) globally. The results, which are only suggestive of the types of effects that would be observed due to the simplifying
cost assumptions, indicate compliance causes supply cutbacks in regulated countries and increases in non-regulated countries.
The study results show that producers in regulating countries are likely to benefit and consumers lose due to commodity price
increases.
Seniority of Authorship is shared among the first three authors. 相似文献
134.
135.
Assessment of nitrogen leaching from arable land in large river basins: Part I. Simulation experiments using a process-based model 总被引:1,自引:0,他引:1
A two-step procedure for analysing nitrogen leaching from arable land in large river basins is suggested: (1) application of a process-based dynamic model for a set of representative conditions in a large river basin to simulate water and nitrogen fluxes and (2) development of a fuzzy-rule based metamodel using the simulated nitrogen fluxes in Step 1 as a training set. After that the metamodel can be used for rapid assessment of water quality inside the considered ranges of parameters, describing natural conditions and management practices. This paper describes Step 1 of the procedure. Step 2 is described in an accompanying paper (Haberlandt et al., Ecological Modelling 150 (3) (2002) 277–294). The advantage of this approach is that it combines the ‘process-based foundation’ with the resulting simplicity of the metamodel. Simulation experiments for analysing nitrogen (N) leaching from arable land were performed using the Soil and Water Integrated Model (SWIM) for a set of representative conditions in the Saale basin (23 687 km2) in Central Europe. The Saale River is one of the main tributaries of the Elbe. In advance, hydrological validation of the model was done for the whole Saale basin and validation of nitrogen dynamics was fulfilled in two mesoscale sub-basins of the Elbe. For the simulation experiments the drainage basin area was sub-divided into five climate zones and nine representative soil classes were chosen. The basic rotation and fertilisation schemes were established using regional information obtained from literature. In addition, the effects of changing the basic rotation to more/less intensive ones and changing fertilisation rates by 50% increase/decrease were studied. The ranges of simulated nitrogen fluxes for the basic rotation and fertilisation schemes are comparable to available regional estimates and differences between sub-regions and soils are plausible. The relative importance of natural and anthropogenic factors affecting nitrogen leaching for the Saale River basin was as follows: (1) soil, (2) climate, (3) fertilisation rate and (4) crop rotation. The simulation experiments provide a basis for a fuzzy-rule based metamodel approach, which aims at rapid water quality assessment of large regions. 相似文献
136.
Kinetics of ammonium removal with suspended and immobilized nitrifying bacteria in different reactor systems 总被引:4,自引:0,他引:4
The degradation of ammonium by free and immobilized bacteria in different reactor systems was investigated. It was found that the start-up of a nitrifying system is enhanced if a reservoir of immobilized bacteria is present. It was also found that in a single stage system with suspended nitrifying bacteria a stable ammonium removal > 95 % could be established up to an influent ammonium concentration of 1000 mg/1 and a volumetric loading rate (VLR) of 2.3 kg NH4+ m−3 d−1. The oxygen uptake rate (OUR) due to nitrification processes was greatly enhanced with increasing volumetric loading rates. Using nitrifying bacteria immobilized on Siran material it was demonstrated that the ammonium degradation rate was directly proportional to the initial ammonium concentration. 相似文献
137.
Urban Geochemistry: Investigations in the Berlin Metropolitan Area 总被引:16,自引:0,他引:16
The distribution of 41 trace and 11 major elements in 4000 samples of topsoils (0–20cm) from the Berlin Megacity is interpreted. The detailed comparative analysis of the element distributions and the results of factor analysis showed that the distributions of the elements Al, K, Na, Rb, Zr, Nb and Ti are mainly natural origin, i.e. related to the composition of the parent material. Industrial and commercial areas often display considerably elevated values for Mo, Ni, As, Ag, Cr, Sb, Fe, Mn, Mg, P, TOC and especially Pb, Hg and electrical conductivity relative to the geogenic background of the area surrounding Berlin. Industrial areas tend to be characterised by contamination of the subsoil with Cu, Cd, Zn, Hg, Pb and Sn. In the area around Berlin, extensive, strong anamalies of Cd, Zn, Pb, Cu and Hg occur near iron and steel industries and construction materials industries, as well as in the vicinity of sewage farms. 相似文献
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