Performance of the single intradermal comparative tuberculin test in identifying cattle with tuberculous lesions in Irish herds

The sensitivity of the single intradermal comparative tuberculin test, as applied in the Republic of Ireland, was estimated in 353 cattle with tuberculous lesions. These cattle had been removed from 47 herds which were depopulated owing to chronic or extensive infection with Mycobacterium bovis. The test had a sensitivity of 90.9 per cent, because 321 (90.9 per cent) of the 353 cattle with tuberculous lesions gave a positive or inconclusive result, and 32 gave a negative result. These 32 negative cattle came from 17 (36 per cent) of the 47 depopulated herds.     

Torsional oscillations of a plane lamina in a buoyant fluid

The correction to the torque on a torsionally oscillating plane in a viscous, thermally conducting fluid due to its density variations is calculated when the thickness of the shear laters us small in comparison to the dimensions of the plane. The mechanism that drives the system away from strictly isothermal conditions is viscous dissipation. The corresponding variations in the mean (axial and radial) flow and the mean temperature are investigated for relatively strong and weak buoyancy-momentum coupling. Method of matched asymptotic expansions is employed to study the resulting fluid motion which exists as a double-decker structure and depends upon three physical parameters.     

MRI demonstration of impairment of the blood-CSF barrier by glucose administration to the thiamin-deficient rat brain

Contrast-enhanced T1-weighted spin-echo magnetic resonance imaging (MRI) has demonstrated that Gd-diethylenetriaminepentaacetate (Gd-DTPA), which normally does not cross the blood-brain or blood-CSF barriers, does so approximately 40 min after administration of glucose to a vitamin B1 deficient rat. The period of the onset of this blood-CSF or blood-brain barrier dysfunction coincides with our previous observations of accumulation of glutamate or glutamate derivatives following an equivalent glucose load under identical conditions of thiamin deficiency, consistent with a relationship between these two observations. The dysfunction was reversed when a thiamin deficient animal was made thiamin replete.     

Mechanical behavior and microstructure characterization of sinter-forged SiC particle reinforced aluminum matrix composites

A novel, low-cost sinter-forging approach to processing particle reinforced metal matrix composites for high-performance applications was examined. The microstructure of the sinter-forged composites exhibited relatively uniform distribution of SiC particles, which appeared to be somewhat aligned perpendicular to the forging direction. The degree of alignment and interparticle bond strength was not as high as that observed for the extruded composite. The sinter-forged composite exhibited higher Young’s modulus and ultimate tensile strength than the extruded material, but lower strain-to-failure. The higher modulus and strength were attributed to the absence of any significant processing-induced particle fracture, while the lower strain-to-failure was caused by poorer matrix interparticle bonding compared to the extruded material. Fatigue behavior of sinter-forged composites was similar to that of the extruded material. Fe-rich inclusions were extremely detrimental to fatigue life. Cleaner processing, which eliminated the inclusions, enhanced the fatigue life of the sinter-forged composites to levels similar to that of the extruded material.     

Tensile Behavior of Single-Crystal Tin Whiskers

The growth of metallic (predominantly Sn) whiskers from pure metallic platings has been studied for over 50 years. While the phenomenon of Sn whiskering has been studied for decades, very little is known about the mechanical properties of these materials. This can be attributed to the difficulty in handling, gripping, and testing such fine-diameter and high-aspect-ratio whiskers. We report on the stress–strain behavior of Sn whiskers inside a dual-beam focused ion beam (FIB) with a scanning electron microscope (SEM). Lift-out of the whiskers was conducted in situ in the FIB, and the whiskers were tested using a microelectromechanical system tensile testing stage. Using this technique, the whiskers had minimum exposure to ambient air and were not handled by hand. SEM images after fracture enabled reliable calculation of the whisker cross-sectional area. Tests on two different whiskers revealed relatively high tensile strengths of 720 MPa and 880 MPa, respectively, and a limited strain to failure of ～2% to 3%. For both whiskers, the Young’s modulus was between 42 GPa and 45 GPa. It is interesting to note that the whiskers were quite strong and had limited ductility. These findings are intriguing and provide a basis for further work to understand the effect of Sn whisker mechanical properties on short circuits in electronics.     

Disparities in arteriovenous fistula placement in older hemodialysis patients

The benefits of an arteriovenous fistula (AVF) as the preferred vascular access for hemodialysis have been clearly demonstrated. However, only about 20% of patients in the United States initiate hemodialysis with an AVF. In this study, we assessed whether disparities exist in the type of first hemodialysis access placed prior to dialysis start (rather than that used at dialysis initiation), to detect whether certain disadvantaged groups might have lower likelihood of AVF placement. Study cohort of 118,767 incident hemodialysis patients ≥67 years of age (1/2005–12/2008) derived from the United States Renal Data System was linked with Medicare claims data to identify the type of initial access placed predialysis. We used logistic regression model with outcome being the initial predialysis placement of an AVF as opposed to an arteriovenous graft or a central venous catheter. Increasing age, female sex, black race, lower body mass index, urban location, certain comorbidities, and shorter pre–end‐stage renal disease nephrology care are all associated with a significantly lower likelihood of AVF placement as initial access predialysis. Our study suggests the presence of significant disparities in the placement of an AVF as initial hemodialysis vascular access. We suggest that additional attention should be paid to these patient groups to improve disparities by patient education, earlier referral, and close follow‐up.     

TRACE qualification via analysis of the EIR gas-loop experiments with smooth rods

Several gas-loop experimental programs were carried out during the 1970–1980s at the Eidgenössisches Institut für Reaktorforschung (EIR, now PSI), Switzerland. In the present work, a wide range of thermal–hydraulics tests for smooth rods, which form part of the experiments conducted at the time, have been reanalyzed with the aim of qualifying the TRACE code. The latter constitutes the thermal–hydraulics module of PSI’s FAST code system, currently being applied to the multi-physics analysis of advanced fast reactor systems, including the Generation IV Gas-Cooled Fast Reactor (GFR). It is shown, from the present analysis, that the built-in TRACE heat transfer and friction correlations are indeed quite suitable for gas cooling under prototypic GFR conditions.