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21.
Cosmological implications of the Machian principle 总被引:1,自引:1,他引:0
The famous idea of Ernst Mach concerning the non-absolute but relational character of particle inertia is taken up in this paper and is reinvestigated with respect to its cosmological implications. From Thirring’s general relativistic study of the old Newtonian problem of the relativity of rotations in different reference systems, it appears that the equivalence principle with respect to rotating reference systems, if at all, can only be extended to the system of the whole universe, if the mass of the universe scales with the effective radius or extent of the universe. A reanalysis of Thirring’s derivations still reveals this astonishing result, and thus the general question must be posed: how serious this result has to be taken with respect to cosmological implications. As we will show, the equivalence principle is, in fact, fulfilled by a universe with vanishing curvature, i.e. with a curvature parameter, which just has the critical density , where is the Hubble constant. It turns out, however, that this principle can only permanently be fulfilled in an evolving cosmos, if the cosmic mass density, different from its conventional behaviour, varies with the reciprocal of the squared cosmic scale. This, in fact, would automatically be realized, if the mass of each cosmic particle scales with the scale of the universe. The latter fact, on one hand, is a field-theoretical request from a general relativistic field theory which fulfills H. Weyl’s requirement of a conformal scale invariance. On the other hand, it can perhaps also be concluded on purely physical grounds, when taking into account that as source of the cosmic metrics only an effective mass density can be taken. This mass density represents the bare mass density reduced by its mass equivalent of gravitational self-binding energy. Some interesting cosmological conclusions connected with this fact are pointed out in this paper. 相似文献
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Michael D Aitken Mark D Sobsey Mina Shehee Kimberly E Blauth Vincent R Hill Joseph B Farrell Sharon P Nappier Glenn W Walters Phillip L Crunk Nicole Van Abel 《Water environment research》2005,77(7):3028-3036
Thermophilic-anaerobic digestion in a single-stage, mixed, continuous-flow reactor is not approved in the United States as a process capable of producing Class A biosolids for land application. This study was designed to evaluate the inactivation of pathogens and indicator organisms in such a reactor followed by batch treatment in a smaller reactor. The combined process was evaluated at 53 degrees C with sludges from three different sources and at 51 and 55 degrees C with sludge from one of the sources. Feed sludge to the continuous-flow reactor was spiked with the pathogen surrogates Ascaris suum and vaccine-strain poliovirus. Feed and effluent were analyzed for these organisms and for indigenous Salmonella spp., fecal coliforms, Clostridium perfringens spores, and somatic and male-specific coliphages. No viable Ascaris eggs were observed in the effluent from the continuous reactor at 53 or 55 degrees C, with greater than 2-log removals across the digester in all cases. Approximately 2-log removal was observed at 51 degrees C, but all samples of effluent biosolids contained at least one viable Ascaris egg at 51 degrees C. No viable poliovirus was found in the digester effluent at any of the operating conditions, and viable Salmonella spp. were measured in the digester effluent in only one sample throughout the study. The ability of the continuous reactor to remove fecal coliforms to below the Class A monitoring limit depended on the concentration in the feed sludge. There was no significant removal of Clostridium perfringens across the continuous reactor under any condition, and there also was limited removal of somatic coliphages. The removal of male-specific coliphages across the continuous reactor appeared to be related to temperature. Overall, at least one of the Class A pathogen criteria or the fecal coliform limit was exceeded in at least one sample in the continuous-reactor effluent at each temperature. Over the range of temperatures evaluated, the maximum time required to meet the Class A criteria by batch treatment of the continuous-reactor effluent was 1 hour for Ascaris suum and Salmonella spp. and 2 hours for fecal coliforms. 相似文献
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Fritz Paneth Richard Lorenz E. Frank E. Wepfer Othenio Abel 《Die Naturwissenschaften》1925,13(16):341-345
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Othenio Abel P. Schulze Hans Böker Hans Munter Moritz v. Rohr 《Die Naturwissenschaften》1925,13(20):435-440
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The Science of Nature - 相似文献
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Lucas Ferrante Augusto Getirana Fabricio Beggiato Baccaro Jochen Schöngart Ana Cristina Monteiro Leonel Renato Gaiga Michel Varajão Garey Philip Martin Fearnside 《Conservation biology》2023,37(3):e14033
Given the speed at which humans are changing the climate, species with high degrees of endemism may not have time to avoid extinction through adaptation. We investigated through teleconnection analysis the origin of rainfall that determines the phylogenetic diversity of rainforest frogs and the effects of microclimate differences in shaping the morphological traits of isolated populations (which contribute to greater phylogenetic diversity and speciation). We also investigated through teleconnection analysis how deforestation in Amazonia can affect ecosystem services that are fundamental to maintaining the climate of the Atlantic rainforest biodiversity hotspot. Seasonal winds known as flying rivers carry water vapor from Amazonia to the Atlantic Forest, and the breaking of this ecosystem service could lead Atlantic Forest species to population decline and extinction in the short term. Our results suggest that the selection of morphological traits that shape Atlantic Forest frog diversity and their population dynamics are influenced by the Amazonian flying rivers. Our results also suggest that the increases of temperature anomalies in the Atlantic Ocean due to global warming and in the Amazon forest due to deforestation are already breaking this cycle and threaten the biodiversity of the Atlantic Forest hotspot. 相似文献
30.
Arsenic bioaccessibility in a gold mining area: a health risk assessment for children 总被引:1,自引:0,他引:1
Ono FB Guilherme LR Penido ES Carvalho GS Hale B Toujaguez R Bundschuh J 《Environmental geochemistry and health》2012,34(4):457-465
High concentrations of total arsenic (As) have been measured in soils of gold mining areas of Brazil. However, bioaccessibility tests have not yet been conducted on those materials, which is essential for better health risk estimates. This study aimed at?evaluating As bioaccessibility in samples from a gold mining area located in Brazil and assessing children's exposure to As-contaminated materials. Samples were collected from different materials (a control and four As-contaminated soils/sediments) found in a gold mine area located in Paracatu (MG), Brazil. Total and bioaccessible As concentrations were determined for all samples. The control soil presented the lowest As concentrations, while all other materials contained high total As concentrations (up to 2,666?mg?kg(-1)) and low bioaccessible As percentage (<4.2%), indicating a low risk from exposure of resident children next to this area. The calculated dose of exposure indicated that, except for the pond tailings, in all other areas, the exposure route considering soil ingestion contributed at most to 9.7% of the maximum As allowed ingestion per day (0.3?μg?kg(-1) BW day(-1)). 相似文献