Relationship between final temperature, thaw rate, and quality of bovine semen

Relationships between thaw rate, thaw bath time, and initial bath and final seminal temperature with coefficients of determination .99 and .97 were: bath time = -.01 + 220.25(1/thaw rate); initial bath temperature = final seminal temperature - 7.29 + 390.05 (1/bath time). Ejaculates from 10 bulls were split and processed in egg yolk-citrate-glycerol, egg yolk-Tris-glycerol, and whole milk-glycerol. All semen was packaged and frozen in .5-ml French straws at -196 degrees C. Sixteen thaw treatments consisted of factorial combinations of four final seminal temperatures and four thaw rates. Treatments were assessed by post-thaw acrosomal integrity after 3-h 37 degrees C incubation. Seminal quality improved with increasing final seminal temperature up to 31 degrees C and did not differ between 31 and 44 degrees C for any of the extenders. A slow thaw rate (3 degrees C/s) resulted in inferior quality for all extenders, and rates 11, 19, and 27 degrees C/s resulted in similar quality for citrate and milk extended semen. Acrosomal integrity was most for 19 degrees C/s in Tris extended semen. A significant factorial interaction existed for Tris and milk extended semen. Predicted acrosomal response of 57.7% across all extenders was at optimum final seminal temperature and thaw rate 37 degrees C and 18 degrees C/s. Bath temperature and bath time determine optimum thaw rate and final temperature of semen packaged in French straws and thus maximize seminal quality.     

Accessing related events increases retroactive interference in a matching recognition test.

Why is memory for a target event impaired by learning related events? Do related events change the trace for the target or hinder retrieval? Target names (e.g., Robert Harris) were shown; experimental items were followed by related names (e.g., Robert Knight) but control items were not. The given names and surnames of the targets were then provided for matching. At short (5–25 min) retention intervals, the control items were matched more accurately than were the experimental items. This retroactive interference (RI) decreased over a 30-min retention interval (Exp 2), suggesting that the related names did not cause a permanent change in the target trace. More RI occurred at the 30-min retention interval when the related names appeared just before the test (Exp 3). It appears that the related names must be accessed to interfere with retrieving the target. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and bioreductive potential of a mono N-oxide derivative of the alkylating agent chlorambucil

Chlorambucil N-oxide (CHLN-O) was synthesized and evaluated for in vitro bioreductive antitumor activity. A time-dependent hypoxic differential was observed when EMT6 cells were exposed to CHLN-O in the presence of rat liver microsomes and reducing equivalents. The cytotoxicity of the N-oxide was potentiated under hypoxia, and augmented further by a combination of low pH and hypoxia. Metabolic studies were also undertaken, which utilized previously described HPLC methodology for the analysis of CHLN-O loss from biological fluids. These demonstrated the requirement for microsomal enzymes and reducing equivalents, and also illustrated the time-dependent manner of CHLN-O loss from isolated microsomal preparations.     

Precision X-ray spectroscopy on 8.5 MeVamu heavy ions

A new experimental capability has been developed at the Lawrence Berkeley Laboratory Super-HILAC to investigate questions relating to high resolution atomic spectroscopy. A key element of these measurements is a dual arm Johann spectrometer. The ion beam passes inside the Rowland circle of two curved crystals which are mounted such that diffracted X-rays have equal and opposite linear Doppler shifts. The X-ray lines are detected with high speed X-ray film mounted on the Rowland circle. The beam-crystal geometry is arranged so a spectral range θ_B ~ 30°–70° is detected. The spectrometer efficiency is high with useful exposures obtained with only 10 mC of beam. A wavelength calibration is obtained by simultaneously exposing the film with diffracted K and L X-rays from an X-ray tube. X-ray lines from the beam are slanted, with respect to the calibration lines, due to Doppler shifts arising from X-rays incident on the crystal at angles other than perpendicular to the diffraction plane. The slope of these lines provides an independent determination of the beam velocity, which is used to correct for the transverse Doppler shift. Typical results are presented.     

Pink discoloration in canned pears III.—Inhibition by chemical additives

Despite the identification of the pigment responsible for discoloration in canned pears as a tin–cyanidin complex, addition of stannous ions to susceptible pear purée prior to processing partly or completely inhibits the discoloration. This effect cannot be obtained with canned pear halves, but other reducing agents, such as sulphur dioxide, are effective inhibitors of the discoloration. By such treatment canned pears of acceptable quality can be produced from varieties which are normally avoided for processing because of their susceptibility to discoloration. A mechanism whereby reducing agents prevent the formation of pink pigments is described, and an explanation is given of the differences in the effect of stannous ions on pear halves and pear purées.     

The statistical concepts of confidence and significance.

"Inasmuch as explicit terminology is needed to convey the probabilities of committing statistical errors in the respective areas of interval estimation and testing hypotheses, the concept of confidence should never be associated with the statistical test of an H regardless of the nature of the test being employed." (PsycINFO Database Record (c) 2010 APA, all rights reserved)