A new solution to an old riddle: elongate dinosaur tracks explained as deep penetration of the foot, not plantigrade locomotion

Palaeontology ◽  
2021 ◽  
Author(s):  
Jens N. Lallensack ◽  
James O. Farlow ◽  
Peter L. Falkingham
2016 ◽  
Vol 46 (185) ◽  
pp. 543-560 ◽  
Author(s):  
Ingo Schmidt

This article draws on Marxist theories of crises, imperialism, and class formation to identify commonalities and differences between the stagnation of the 1930s and today. Its key argument is that the anti-systemic movements that existed in the 1930s and gained ground after the Second World War pushed capitalists to turn from imperialist expansion and rivalry to the deep penetration of domestic markets. By doing so they unleashed strong economic growth that allowed for social compromise without hurting profits. Yet, once labour and other social movements threatened to shift the balance of class power into their favor, capitalist counter-reform began. In its course, global restructuring, and notably the integration of Russia and China into the world market, created space for accumulation. The cause for the current stagnation is that this space has been used up. In the absence of systemic challenges capitalists have little reason to seek a major overhaul of their accumulation strategies that could help to overcome stagnation. Instead they prop up profits at the expense of the subaltern classes even if this prolongs stagnation and leads to sharper social divisions.


2008 ◽  
Author(s):  
Xudong Zhang ◽  
Eiji Ashida ◽  
Seiji Katayama ◽  
Masami Mizutani

1997 ◽  
Author(s):  
Phiroze Kapadia ◽  
Pablo Solana ◽  
John Dowden

1993 ◽  
Vol 27 (7-8) ◽  
pp. 173-178 ◽  
Author(s):  
M. Zilberbrand

In a thick unsaturated zone, when quick deep penetration of rain and irrigation water is absent, at the depths below 3-5 m there exists a zone of downwards quasi-steady water flow. Darcy's water velocity in this zone remains constant with depth and equal to the groundwater recharge rate; unit hydraulic head gradient occurs above the capillary fringe. Therefore, contaminant travel rate is equal to the ratio of hydraulic conductivity (K) and effective volumetric water content (θef). Field tracer experiments and laboratory K and θef determinations were carried out for several representative irrigated lots in the South Ukraine. The dependence of θef on capillary tension was studied for the first time. For loess loam with a capillary tension decreasing from 46 kPa to 0, θef nonlinearly increases from 12% to 27-28%. The effective water content portion (β1) of the total water content increases nonlinearly from 0.38 to 0.65-0.7. The β1 values were estimated for different unsaturated sedimentary rocks. For a capillary tension of about 5 kPa β1 values were: 0.88-0.99 for sands, about 0.65 for loess loam and chestnut soil, about 0.6 for sandy loam, about 0.32 for limestone and about 0.07 for clay. Calculated chloride travel rates in loess loams under irrigated soils fit the values of 0.001-0.003 m/day, determined by the results of field tracer experiments.


2015 ◽  
Vol 40 (5) ◽  
pp. 492-502 ◽  
Author(s):  
GC Oliveira ◽  
AP Boteon ◽  
FQ Ionta ◽  
MJ Moretto ◽  
HM Honório ◽  
...  

SUMMARY Resin-based materials that show promising effects for preventing the progression of erosion have been studied. This in vitro study evaluated the effects of applying resin-based materials, including resin infiltration, on previously eroded enamel subjected to erosive challenges. The influence of enamel surface etching prior to application of the material was also studied. Bovine enamel blocks were immersed in hydrochloric acid (HCl), 0.01 M (pH 2.3), for 30 seconds in order to form a softened erosion lesion. The blocks were then randomly divided into nine groups (n=12) and treated as follows: C = control without treatment; Hel = pit & fissure resin sealant (Helioseal Clear); Adh = two-step self-etching adhesive system (AdheSe); Tet = two-step conventional adhesive system (Tetric N-bond); and Inf = infiltrant (Icon). The Helno, Adhno, Tetno, and Infno groups received the same materials without (or with no) surface conditioning. The depth of the material's penetration into softened erosion lesions was qualitatively analyzed using reflection and fluorescence confocal microscopy. After application of the materials, the blocks were immersed in HCl for two minutes; this step was followed by immersion in artificial saliva for 120 minutes four times a day for five days (erosive cycling). Both the enamel alteration and material thickness were analyzed using profilometry, and the results were submitted to Kruskal-Wallis and Dunn tests (p>0.05). Images from the confocal microscopy showed minimal penetration of Adh/Adhno and deep penetration of Inf/Infno into the erosive lesions. The groups Hel, Adh, Inf, Tetno, and Infno resulted in the formation of a layer of material over the enamel, which was effective in inhibiting the progression of erosion. In conclusion, the infiltrant, with or without etching, was able to penetrate and protect the enamel against dental erosion. The other resin-based materials, except for the two-step conventional adhesive, were able to penetrate and inhibit the progression of erosive lesions only when they were applied after enamel etching.


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