Effects of polybrominated biphenyls on health and performance of pregnant Holstein heifers.

The toxicity of a commercial blend of polybrominated biphenyls was determined in 24 pregnant Holstein heifers that were allotted randomly to one of four experimental groups given 0, .25, 250, or 25,000 mg/day of fire-Master BP-6. The polybrominated biphenyls were mixed with finely ground corn and given by bolus for 60 days or until the animal became moribund. Average body weight of heifers at onset of experiment was 381 kg. No clinical signs of toxicosis were evident in heifers fed 0, .25 or 250 mg/day. Toxicosis was induced in heifers fed 25,000 mg/day resulting in reduced dry matter intake, body weight, heart rate, and respiration rate. Clinical signs were anorexia, emaciation, dehydration, excessive lacrimation and salivation, diarrhea, depression, and abortion or fetal death. All heifers fed 25,000 mg/day became moribund within 33 to 66 days.     

Nonlactating-cow therapy with a formulation of penicillin and novobiocin: therapeutic and prophylactic effects

An experimental product incorporating 500,000 IU of procaine penicillin G and 600 mg of sodium novobiocin in 2% aluminum monostearate-peanut oil gel (10-ml dose) was infused after the final milk-out at end of lactation into all 4 mammary quarters of 56 cows that were infected in at least 1 quarter. The therapeutic and prophylactic efficacies were published in the companion report. Infusion of the product in all quarters of 5 lactating cows resulted in only slight irritation. Penicillin was eliminated by the 11th milking and novobiocin by the 5th. After infusion in the dry udder, the antibiotics were no longer detectable in serous secretion after 14 days and failed to appear in urine at the earliest (7-day) sampling after administration. Neither antibiotic was detectable in the 1st postpartum milking after nonlactating periods as short as 3 weeks.     

Effects of counselor statements on rater judgments of client self-exploration.

Examined the influence of counselor statements on rater judgements of client self-exploration. Audiotaped segments of counseling interviews that included both counselor and client statements and identical autiotaped segments, but with the counselors' statements deleted, were rated on client self-exploration by separate groups of raters (totaling 20 counseling graduate students). A significantly positive correlation was found between the 2 sets of ratings. With 1 exception, no significant differences were found for each segment. Finally, no differences were found between ratings for segments, unedited and edited, in which counselors were functioning at high levels of accurate empathy and ratings in which counselors were functioning at low levels of accurate empathy. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photolithographic Fabrication and Physiological Performance of Microelectrode Arrays for Neural Stimulation

The development of an auditory cochlear prosthesis which works by direct electrical stimulation of the auditory nerve creates the need for a multielectrode stimulation array which is small in size, rugged, resistant to electrolysis, and stable and reproducible in its electrical and mechanical properties. This paper describes the fabrication of such microelectrode arrays using planar lithographic techniques.     

Poly(phenylquinoxaline-imide-amide)s containing perfluoroisopropylidene units

Poly(phenylquinoxaline-imide-amide)s have been synthesized by solution polycondensation of aromatic diamines containing preformed phenylquinoxaline units with diacid dichlorides incorporating preformed imide rings and perfluoroisopropylidene units. These polymers show high thermal stability; they decompose above 400°C and have glass transition temperatures in the 225–290°C range. Comparison of these compounds with related heterocyclic polymers leads to the conclusion that the decomposition of the former ones begins with the destruction of amide groups. Films prepared from polymer solutions showed good electrical insulating properties, comparable to those of a standard film (Film H). The highest quality of these poly(phenylquinoxaline-imide-amide)s is their remarkable solubility in polar aprotic solvents, which is very important for practical applications.     

Driver Deadtime Control and Its Impact on System Stability of Synchronous Buck Voltage Regulator

Driver dead-time control is a popular scheme used to prevent the occurrence of the shoot-through issue in a synchronous Buck voltage regulator. As the switching frequency is continually increasing in today's converter design, the deadtime interval is now long enough relative to the switching period to impact the system performance. In addition to its impact on efficiency, driver dead-time also impacts loop gain and system stability, especially under the critical load condition. In this paper, the influence of driver dead time on the synchronous buck converter is investigated in detail. With voltage mode control, the system loop gain will change under different load conditions due to the deadtime impact. The deadtime may cause sub-harmonic current ripple in the voltage regulator with sample-and-hold current mode control, while its impact on the peak current mode control can be ignored. Design equations are provided to avoid this issue. Some analysis data are included and compared to experimental results.     

An investigation of the fatigue and fracture behavior of a Nb-12Al-44Ti-1.5Mo intermetallic alloy

This article presents the results of a study of the fatigue and fracture behavior of a damage-tolerant Nb-12Al-44Ti-1.5Mo alloy. This partially ordered B2 + orthorhombic intermetallic alloy is shown to have attractive combinations of room-temperature ductility (11 to 14 pct), fracture toughness (60 to 92 MPa√m), and comparable fatigue crack growth resistance to IN718, Ti-6Al-4V, and pure Nb at room temperature. The studies show that tensile deformation in the Nb-12Al-44Ti-1.5Mo alloy involves localized plastic deformation (microplasticity via slip-band formation) which initiates at stress levels that are significantly below the uniaxial yield stress (∼9.6 pct of the 0.2 pct offset yield strength (YS)). The onset of bulk yielding is shown to correspond to the spread of microplasticity completely across the gage sections of the tensile specimen. Fatigue crack initiation is also postulated to occur by the accumulation of microplasticity (coarsening of slip bands). Subsequent fatigue crack growth then occurs by the “unzipping” of cracks along slip bands that form ahead of the dominant crack tip. The proposed mechanism of fatigue crack growth is analogous to the unzipping crack growth mechanism that was suggested originally by Neumann for crack growth in single-crystal copper. Slower near-threshold fatigue crack growth rates at 750 °C are attributed to the shielding effects of oxide-induced crack closure. The fatigue and fracture behavior are also compared to those of pure Nb and emerging high-temperature niobium-based intermetallics.     

JWL++: A Simple Reactive Flow Code Package for Detonation

JWL++ is a simple Reactive Flow model that includes time‐dependent reaction in prompt detonation. It consists of a Murnahan unreacted equation of state, a JWL reacted EOS, a mixer for the two EOS's and a single‐time‐constant exponential rate. The mixing can be done by four ways, using either pressure or pressure plus artificial viscosity in the rate, and also using either an analytic function or a pressure equilibrator. The model reproduces the Size Effect and detonation front curvature. Detonation failure can also be induced. JWL++ propagates also through an arbitrary geometry in 3‐D without the need for pre‐run program burn calculations. It is slower than a JWL/program “Burn” but faster than “Ignition & Growth”.     

Tracking severe weather storms in Doppler radar images

We describe an automatic storm-tracking system to help with the forecasting of severe storms. In this article, we present the concepts of fuzzy point, fuzzy vector, fuzzy length of a fuzzy vector, and fuzzy angle between two nonzero fuzzy vectors, that are used in our tracking algorithm. These concepts are used to overcome some of the limitations of our previous work, where fixed center-of-mass storm centers did not provide smooth tracks over time, while at the same time, their detection was very threshold sensitive. Our algorithm uses region splitting with dynamic thresholding to determine storm masses in Doppler radar intensity images. We represent the center of a hypothesized storm using a fuzzy point. These fuzzy storm centers are then tracked over time using an incremental relaxation algorithm. We have developed a visualization program using the X11 Athena toolkit for our storm visualization tool. The algorithm was tested on seven real radar image sequences obtained from the Atmospheric Environment Service radar station at King City, Ontario, Canada. We can obtain storm tracks that are long and smooth and which closely match an expert meteorologist's perception. © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 201–213, 1998