Detrital Zircon Link Between Headwaters and Terminus of the Upper Triassic Chinle-Dockum Paleoriver System

New detrital-zircon geochronologic data reveal that a through-going paleoriver connected Texas with Nevada in Late Triassic time. Sandstone from the Upper Triassic Santa Rosa Sandstone (Dockum Group) from northwestern Texas contains a detrital zircon suite nearly identical to that found in western Nevada in the Upper Triassic Osobb Formation (Auld Lang Syne Group, correlative with the Chinle Formation). The Santa Rosa Sandstone was derived in large part from the eroded Cambrian core of the Amarillo-Wichita uplift, as evidenced by abundant zircons with ages of 515 to 525 million years. Other zircon grains in the sandstone are Permian, Devonian, Proterozoic, and Archean in age and, with the exception of the Archean grain, are also matched by the population in the Nevada strata.     

OPTIMALLY PARTITIONING SOIL TRANSECTS

Two methods are described for locating soil boundaries on transects from multivariate data. One method (split moving-window, SMW) examines a transect through a window which is split at its mid point and the two halves compared. The window is moved along the transect and a boundary inferred wherever the difference between the two halves attains a local maximum. The other (maximum level-variance, MLV) examines all possible partitions of a transect that can be produced by a given number of boundaries or less and places boundaries in those positions that minimize the within-segment sum of squared deviations from the segment means (and hence maximize the between-segment sum of squares). The performances of the two methods are compared for two soil transects in Oxfordshire. MLV identified all major changes even where gradual, but was less reliable for small changes. SMW identified all sharp boundaries, even between soil types that are fairly similar. In its original form SMW did not identify gradual changes reliably, but its performance was improved both by omitting data near the centre of the window and by concentrating the discriminating power of the data beforehand as in MLV. SWM requires less computing than MLV.     

SONOGRAPHIC ASSESSMENT OF GALLBLADDER VOLUME IN NORMAL CATS

We quantified gallbladder volume in 30 clinically healthy, fasted, cats, using an ellipsoid formula. All cats had a complete blood count and serum chemistry profile performed. Fasting times before sonography ranged from 12 to 16 h. The median gallbladder volume was 2.42 ml, with a range of 0.84–4.50 ml. The mean gallbladder volume was 2.41 ml. This reference range will assist clinicians when evaluating cats with hepatobiliary disease or suspected extrahepatic biliary obstruction.     

Comparison of immune response stimulated in sheep, rabbits and guinea pigs by the administration of multi-component clostridial vaccines

Over 3 years, the immunogenic responses of various batches of multi-component clostridial vaccines in sheep, rabbits and guinea pigs were compared. Fully susceptible healthy sheep were found to be more suitable than rabbits or guinea pigs for testing the potency of multi-component clostridial vaccines containing Clostridium novyi type B, C. perfringens type D, C. septicum and C. tetani, and recommendations are made that sheep are the preferred species for testing the potency of clostridial vaccines.     

Assessment of organoleptic postmortem inspection techniques for bovine offal

Objective To evaluate organoleptic postmortem inspection techniques for bovine livers and kidneys.
Study design At Australian export abattoirs, bovine liver and kidneys are assessed and graded by qualified meat inspectors during normal operations. Over a 12-month period at a large abattoir in eastern Australia during 1997 and 1998, a sample of these organs was reassessed independently using a range of pathological and microbiological methods. Agreement between routine inspection and independent assessment was evaluated using methods of inter-rater agreement.
Results A total of 944 livers and 1374 kidneys were included in the study. All of these organs had been classified during routine inspection. The authors examined 363 livers and 329 kidneys both grossly and histologically, including 36 livers and 14 kidneys that were also subjected to microbiological examination. All other organs were only examined grossly. There was only a moderate level of agreement between the routine and independent assessment methods. For livers, the percentage agreement was 80.2%, McNemar's test of symmetry 55.2 (3 degrees of freedom, P < 0.001) and kappa 0.63. For kidneys, the percentage agreement was 67.8%, McNemar's test of symmetry 9.9 (1df, P = 0.002) and kappa 0.35.
Conclusions The results reinforce concerns from a number of authors about organoleptic postmortem inspection. Risk assessment methodologies offer the opportunity to modify inspection techniques in a manner that is most relevant to current public health concerns.     

Efficacy of zeta-cypermethrin as pour-on or spray formulations for the control of buffalo fly (Haematobia irritans exigua) in cattle

Objective To determine the efficacy of zeta-cypermethrin in controlling buffalo fly ( Haematobia irritans exigua ).
Design Five field trials in northern and central Queensland.
Procedure Zeta-cypermethrin pour-on at 2.5 mg/kg, spray at 62.5 ppm, deltamethrin pour-on and pour-on vehicle were applied to groups of 20 cattle. Buffalo fly counts were conducted three times before treatment and 3, 7, 14, 21, 28 and 35 days after treatment.
Results In central Queensland where synthetic pyrethroid resistance in buffalo fly populations was rare, 2.5 mg/kg of zeta-cypermethrin pour-on gave good control of buffalo fly for 4 weeks and was better than a deltamethrin product. A zeta-cypermethrin spray used at 62.5 ppm gave 14 days control. In far-north Queensland where resistance to synthetic pyrethroids and heavy rain was common, the maximum period of efficacy of zeta-cypermethrin pour-on was reduced to 2 weeks.
Conclusion In areas where there is low resistance to synthetic pyrethroids among buffalo flies, zeta-cypermethrin pour-on can be expected to give good control for 4 weeks.     

The topology of pore structure in cracking clay soil I. The estimation of numerical density

The numerical density, N_v , of the pore structure of soil is the number of disjoint networks of pores per unit volume of soil. A method is described for estimating N_v of patterns of cracks that dominate in many clay subsoils. The cracks are photographed from numerous close-spaced parallel sections and skeletonized; by comparing the skeletonized photographs sequentially, individual networks are tracked from one section to another and counted. The average number of networks that appears or disappears per section in the sequence is a measure of the numerical density and is obtained by regressing the counts on the volume of soil spanned by the sections. The regressions for appearances and disappearances converge on one another and stabilize within 10 to 20 sections, so that N_v can be estimated for a sample of soil with moderate effort.
Estimates of N_v for cracks wider than 60 μm in subsoil of the Windsor series, sampled at two nearby sites and 5 years apart in time and determined from sections at 50 μm intervals, were approximately 32 cm⁻³ and 36cm⁻³. That of N_v in the Swanwick series subsoil nearby was about 75 cm⁻³.