Clay plains and geomorphic history of the central Sudan A review

The paper presents an analysis of the Sudan clay plain. Total plain area is 500,000 sq. km., but the paper focuses on an area of 90,000 sq. km.In the east-central Sudan an old erosion surface between600m× 730m above sea level is probably Miocene in age. The main plainlands lie 200 – 300 m below this and date from entertiary times. Evidence of an “African” surface may occur on skeletal volcanoes near Gedaref.Downwarping along NNW-SSE lines formed distinctive basins including the Blue Nile basin. Sediments accumulated in the basins and a sequence of arkose, paludal sandy clay, alluvial sand, silt and clay in the Blue Nile basin is capped by modern silt and clay which has weathered to form a clay soil.The clays on the plain vary in age from upper Pliocene to modern though the weathering seems in balance with a somewhat wetter climate than at present. The clays dominantly on almost level plains are alluvial or lacustrine. The remainder is residual or colluvial weathered material on flat but extremely gently sloping interfluves on higher ground.The clay of the aggradational plains in the Blue Nile basin has been reworked continuously by the rivers and is therefore, much younger than the clay on the degradational plains which is upper Pliocene to Middle Phistocene in age. The present Blue Nile flows in a wide alluvial valley with the channel incised up to 24 m below the general plain.     

Soil catenas to estimate ages of movements on normal fault scarps, with an example from the Wasatch fault zone, Utah, USA

Trenches excavated across fault scarps on a 13 ka delta surface at Brigham City, Utah, USA, document four types of soil-catena phenomena. First, the relict summit soil is eroded at the scarp crest, and its components incorporated into the accumulating colluvial wedge at the scarp base. Second, the pre-faulting soil weakens laterally as it is traced scarpward beneath the colluvial wedge from a relict position beyond the scarp toe. Third, soils developed on individual colluvial wedges and on the underlying, pre-faulting surface merge downslope to form a cumulative soil profile at the scarp toeslope. Fourth, soil horizons thicken downslope, probably due to the combined affect of more available moisture, water infiltration, and sediment accumulation.Two soil catenas were used to evaluate the applicability of a continuity approach to paleoearthquake dating, by which percentages of total development time represented by each soil at a fault scarp footslope could be estimated. The continuity approach sets total soil development at the scarp footslope, including any buried pre-faulting soil plus the sum development of all colluvial wedge soils corrected by a slope factor (F), equal to total soil development at the scarp summit. Soil development was characterized by Profile Development Index (PDI) and pedogenic clay parameters, using facies models to estimate parent material values for genetically-different colluvial units, and recognizing inherited soil components in colluvial wedges as parent material properties. The F slope factor, used to correct colluvial wedge soils for development attributable to slope position rather than age, was checked by using a nearby fluvial scarp as an independent control. Our soil data, when compared to independent age estimates, imply that rates of soil development have not been constant over the last 13 ka at Brigham City, but rather were considerably higher than average between 13 ka and 8.3 ka. Higher rates are probably due to a relatively high influx of eolian dust during the late Pleistocene to early Holocene following the lowering of Lake Bonneville, a large paleolake in the western USA. These variable rates of soil development preclude using the continuity approach for paleoearthquake dating at Brigham City. However, promising results showing that generally consistent F factors can be calculated for fault and fluvial scarps leave open the possibility that in areas where soil development rates have been relatively constant over the time period in question, the continuity approach may be a broadly applicable method for paleoearthquake dating.     

Within‐ and across‐breed imputation of high‐density genotypes in dairy and beef cattle from medium‐ and low‐density genotypes

The objective of this study was to evaluate, using three different genotype density panels, the accuracy of imputation from lower‐ to higher‐density genotypes in dairy and beef cattle. High‐density genotypes consisting of 777 962 single‐nucleotide polymorphisms (SNP) were available on 3122 animals comprised of 269, 196, 710, 234, 719, 730 and 264 Angus, Belgian Blue, Charolais, Hereford, Holstein‐Friesian, Limousin and Simmental bulls, respectively. Three different genotype densities were generated: low density (LD; 6501 autosomal SNPs), medium density (50K; 47 770 autosomal SNPs) and high density (HD; 735 151 autosomal SNPs). Imputation from lower‐ to higher‐density genotype platforms was undertaken within and across breeds exploiting population‐wide linkage disequilibrium. The mean allele concordance rate per breed from LD to HD when undertaken using a single breed or multiple breed reference population varied from 0.956 to 0.974 and from 0.947 to 0.967, respectively. The mean allele concordance rate per breed from 50K to HD when undertaken using a single breed or multiple breed reference population varied from 0.987 to 0.994 and from 0.987 to 0.993, respectively. The accuracy of imputation was generally greater when the reference population was solely comprised of the breed to be imputed compared to when the reference population comprised of multiple breeds, although the impact was less when imputing from 50K to HD compared to imputing from LD.     

DORSAL PLANE COMPUTED TOMOGRAPHIC IMAGING OF THE ETHMOID REGION TO EVALUATE CHRONIC NASAL DISEASE IN THE DOG

Computed tomographic anatomy of the normal canine ethmoid region using both transverse and dorsal imaging plane is described. In the transverse plane, the cribriform plate appears as an irregular heart-shaped to rectangular structure that is generally visualized on no more than one to two contiguous 4-mm slices. In the dorsal plane, the cribriform plate appears as a discrete "V"-shaped structure and can be visualized on four to five contiguous slices. Successful visualization of the cribriform was less dependent on patient positioning for the dorsal plane imaging studies. Computed tomographic findings in four dogs with chronic nasal disease and complete postmortem examination of the ethmoid region indicate that the dorsal imaging plane allows a more accurate assessment of cribriform plate involvement than the transverse imaging plane.     

Host plant stimulation of detoxifying enzymes in a phytophagous insect

The midgut microsomal aldrin epoxidase of variegated cutworm larvae (Peridroma saucia, Hübner) fed bean or peppermint leaves was up to 10 and 45 times more active, respectively, than that of larvae fed a basic control diet. Large increases in oxidase activity and cytochrome P-450 levels also occurred in larvae fed mint plant constituents such as menthol menthone, α-pinene, and β-pinene. Mint-fed larvae were more tolerant of the insecticide, carbaryl, than bean-fed larvae.     

OSTEOSARCOMA OF THE PATELLA WITH PULMONARY METASTASES IN A DOG

A 6-year-old neutered male Rottweiler was examined for a progressive right pelvic limb lameness. In radiographs of the right stifle, there was an osteolytic lesion with irregular new bone formation along the cranial aspect of the patella consistent with an aggressive bone lesion. In thoracic radiographs, there were multiple soft tissue nodular opacities throughout the lung fields, consistent with pulmonary metastases. Microscopically, fine needle aspirate samples from the right patella contained pleomorphic spindle cells with cytologic features of osteosarcoma. The presence of pulmonary metastases at the time of initial diagnosis in the dog described herein suggests that osteosarcoma of the patella has the potential for similar aggressive biologic behavior as that seen in dogs with appendicular osteosarcoma.