Measurements of Texture of Soils Formed from Glaciolimnic Sediments by Areometric Method, Pipette Method and Laser Diffraction Method
Abstract The aim of the research was to compare the results of texture analyses of glaciolimnic sediments deposited in the basins of ice-dammed lakes origin in north eastern Poland. The study was carried out using aerometric method, pipette method and laser diffraction method. The studied soils were classified as Haplic and Mollic Vertisol, Vertic Cambisol, and Gleyic Chernozem. The soils were formed from clayey (clay, heavy clay), loamy (loam, clay loam, sand clay loam) and silty (silt loam, clay loam) deposits. The studied soils did not contain fractions > 2.0 mm. The amounts of clay fraction (< 0.002 mm) measured by areometric and pipette methods were similar and strongly correlated. In comparison to laser diffraction method, these amounts were 3-4-fold higher. The sub-fraction of fine silt (0.02-0.002 mm) predominated in soil formations analyzed by laser diffraction method. In comparison to areometric or pipette method, the amounts of fine silt were 2-4 fold higher. Basing on the calculated sedimentological indices, it was stated that the examined soils were well sorted and the mean grain diameter (GSS) was very low and did not exceed 0.005 mm in areometric and pipette methods, and 0.011 mm in laser diffraction method for clay sediments.
Soil grain size analysis by the dynamometer method – a comparison to the pipette and hydrometer method
Abstract The aim of the presented work was to compare the results of grain size distribution measurement by an innovative dynamometer method, developed by the authors, with results obtained by the pipette and hydrometer methods. Repeatability of results obtained in the dynamometer method was also determined. The content of three fractions with equivalent diameters <0.002 mm, 0.002–0.063 mm and 0.063–2.0 mm was measured. The results were compared using ordinary linear regression and additionally in the repeatability analysis by RMA (reduced major axis regression). It was found that the proposed dynamometer method is characterized by good result repeatability with no systematic errors when compared with the pipette method. The RMSE (root mean square error) value when referring to the pipette method calculated for the three fractions considered in total was 4.9096 and was lower than the analogous for the hydrometer method, which amounted to 5.4577. Values of determination coefficients in the comparison of dynamometer method and pipette method are within the range of 0.9681–0.9951 for the different fractions. It was found that slightly larger differences in relation to the pipette method occurred for the fractions <0.002 mm and 0.002–0.063 mm, and smaller for the fraction 0.063–2.0 mm. Similarly, greater differences between repetitions in the dynamometer method were observed for the fraction <0.002 mm, and smaller for the 0.063–2.0 mm fraction. Possible sources of errors in the dynamometer method were discussed, as were proposals for their reduction.
Developers of the hepatitis B vaccine.
air at VA facilities, one of the many pieces of unfinished business beyond those major issues that we discussed in our Commentary. We agree that all facilities where current and past military personnel serve and receive treatment should be 100% smoke-free and note the recent Institute of Medicine report Combating Tobacco in Military and Veteran Populations. The report, which was commissioned by the Department of Defense (DOD) in 2007, calls for the DOD to set a timeline to eliminate smoking on military installations. The report also recommends that the DOD stop selling tobacco products in military commissaries and exchanges, prohibit tobacco use anywhere on military installations, and treat tobacco use in the same way as other health-related behaviors, such as alcohol abuse and poor physical fitness. We join Matthews and the Institute of Medicine in urging the VA and the DOD to take more immediate steps to protect the health of the men and women who serve in the armed services, as well as the civilians (such as Dr Matthews) working to serve them.