Whole milk extender with antibiotics to eliminate Campylobacter fetus from frozen bovine semen

Fresh bovine semen was contaminated with five strains of Campylobacter fetus at 10(5) to 10(6) organisms per ml of semen. The contaminated semen was processed to contain 500 units of polymyxin B, 500 units of penicillin G, and 1000 micrograms of streptomycin sulfate per ml, incubated at 35 degrees C for 10 min, and added then to whole milk extender with like units of antibiotics for further processing. Both a low and high initial sperm count requiring extension rates 1:7 and 1:39 were studied. Specimens for bacterial viability were processed for culture prior to adding bacteria, 100 min after initial antibiotic treatment, prior to freezing, and after thawed semen was centrifuged and washed to remove extender and antibiotic residue. All strains of Campylobacter fetus were not viable 6 h postantibiotic treatment prior to freezing. All nonantibiotic treated controls were viable after thawing and washing. Removal of antibiotics from thawed semen by centrifugation and washing indicated that antibiotics had bactericidal rather than only bacteriostatic activities against Campylobacter fetus.     

Efficient identity-based RSA multisignatures

A digital multisignature is a digital signature of a message generated by multiple signers with knowledge of multiple private keys. In this paper, an efficient RSA multisignature scheme based on Shamir's identity-based signature (IBS) scheme is proposed. To the best of our knowledge, this is the first efficient RSA-based multisignature scheme with both fixed length and the verification time. The proposed identity-based multisignature scheme is secure against forgerability under chosen-message attack. It is also secure against multi-signer collusion attack and adaptive chosen-ID attack.     

Threshold proxy re-signature: definition and new constructions

The previous threshold proxy re-signature schemes have been mainly constructed with bilinear maps, the implementations of which are much more time-consuming than exponentiation operations. To solve this problem, we propose efficient threshold proxy re-signature schemes which are constructed with El-Gamal signatures. The performance analysis shows that our schemes are more efficient than the existing threshold proxy re-signature schemes. Based on the discrete logarithm problem, our schemes are provable secure in the random oracle model.     

Experiences with the New York State Bovine Leukosis Virus Eradication and Certification Program

The Diagnostic Laboratory at the Veterinary College at Cornell University has offered a bovine leukosis virus (BLV) eradication/ certification program since 1985. The program has been popular with purebred breeders since its inception. Recently, many commercial dairymen have also begun participating to reduce the high incidence of clinical leukosis observed in their heavily infected herds. Eradication is achieved through a management and testing program designed to meet the needs of each farm. Over the years, experiences and observations have elucidated a number of factors that significantly affect the rate of progress and time required for a herd to become "BLV-Free."     

Effect of low copper content and heat treatment on intergranular corrosion of model AlMgSi alloys

Certain 6000-series extrusions may develop susceptibility to intergranular corrosion (IGC) by improper heat treatment, especially if copper is present as an alloying element. Although occurrence of IGC in such cases is documented, the underlying mechanisms are not adequately explained. We present corrosion data for two model alloys, having different Cu content and Mg:Si ratio, showing that the susceptibility to IGC depended primarily on the Cu content and secondly on thermal processing. Low Cu samples (0.0005 wt.% Cu) were essentially resistant to IGC. High Cu samples (0.12 wt.% Cu), which were air cooled after extrusion, exhibited significant IGC. However, IGC susceptibility was reduced significantly as a result of artificial aging to peak strength. Water quenched high Cu samples were essentially resistant to IGC. However, slight IGC susceptibility was introduced after aging. Electron optical characterisation revealed Al₄Mg₈Si₇Cu₂ (Q-phase) grain boundary precipitates on all the variants susceptible to IGC. The susceptibility was attributed to microgalvanic coupling between Q-phase grain boundary precipitates (noble) and the adjacent depleted zone (active).