Growth of a Richtmyer-Meshkov turbulent layer after reshock

This paper presents a numerical study of a reshocked turbulent mixing layer using high-order accurate Implicit Large-Eddy-Simulations (ILES). Existing theoretical approaches are discussed, and the theory of Youngs (detailed in Ref. 1) is extended to predict the behaviour of a reshocked mixing layer formed initially from a shock interacting with a broadband instability. The theory of Mikaelian2 is also extended to account for molecular mixing in the single-shocked layer prior to reshock. Simulations are conducted for broadband and narrowband initial perturbations and results for the growth rate of the reshocked layer and the decay rate of turbulent kinetic energy show excellent agreement with the extended theoretical approach. Reshock causes a marginal decrease in mixing parameters for the narrowband layer, but a significant increase for the broadband initial perturbation. The layer properties are observed to be very similar post-reshock, however, the growth rate exponent for the mixing layer width is higher in the broadband case, indicating that the reshocked layer still has a dependence (although weakened) on the initial conditions. These results have important implications for Unsteady Reynolds Averaged Navier Stokes modelling of such instabilities

The Sporting Set Winters in Florida: Fertile Ground for the Leisure Revolution, 1870-1930

Maurice Fatio made his first visit to Palm Beach, Florida, at the height of the social season in February 1923. The young Swiss architect planned on trolling for business among the resort\u27s elite guests, hoping to supplement his New York City firm\u27s clientele. The pace and nature of the Palm Beach scene, however, caught him by surprise. In a letter to his parents written on the fourth day of his visit, he exclaimed, I have never led a more intense life. Describing a typical day, he explained that one gets up at 10 o\u27clock to play tennis; at noon one bathes at a splendid beach . . . golf in the afternoon . . . and the day ends with magnificent balls in private homes which are veritable palaces. While he admitted that he had not yet had time to attend to his business, the exhausting lifestyle made him \u27feel physically marvelous. Fatio\u27s letter hints at the central role sport and outdoor recreation played in shaping everyday activities and the sense of place that helped define wintering in Florida

Cryopreservation of Preimplantation Embryos of Cattle, Sheep, and Goats

Preimplantation embryos from cattle, sheep, and goats may be cryopreserved for short- or long-term storage. Preimplantation embryos consist predominantly of water, and the avoidance of intracellular ice crystal formation during the cryopreservation process is of paramount importance to maintain embryo viability. Embryos are placed into a hypertonic solution (1.4 – 1.5 M) of a cryoprotective agent (CPA) such as ethylene glycol (EG) or glycerol (GLYC) to create an osmotic gradient that facilitates cellular dehydration. After embryos reach osmotic equilibrium in the CPA solution, they are individually loaded in the hypertonic CPA solution into 0.25 ml plastic straws for freezing. Embryos are placed into a controlled rate freezer at a temperature of -6°C. Ice crystal formation is induced in the CPA solution surrounding the embryo, and crystallization causes an increase in the concentration of CPA outside of the embryo, causing further cellular dehydration. Embryos are cooled at a rate of 0.5°C/min, enabling further dehydration, to a temperature of -34°C before being plunged into liquid nitrogen (-196°C). Cryopreserved embryos must be thawed prior to transfer to a recipient (surrogate) female. Straws containing the embryos are removed from the liquid nitrogen dewar, held in room temperature air for 3 to 5 sec, and placed into a 37°C water bath for 25 to 30 sec. Embryos cryopreserved in GLYC are placed into a 1 M solution of sucrose for 10 min for removal of the CPA before transfer to a recipient (surrogate) female. Embryos cryopreserved in EG, however, may be directly transferred to the uterus of a recipient

Assessment of BoviPureTM for the In Vitro Production of Bovine Embryos

The objective of this study was to examine the potential utility of a commercially available sperm separation and purification product for the in vitro production of bovine embryos. Bovine oocytes were purchased from a commercial supplier, and matured oocytes were randomly allocated to one of two treatments. Oocytes were co-incubated with frozen-thawed semen washed twice with BoviPureTM (BoviPure group) or with modified Brackett-Oliphant medium (control group). After a 6-hour insemination period, oocytes were cultured in vitro for 8 days. Cleavage rate of embryos was determined 48 hours post-insemination, and blastocyst formation rate was assessed on day 8 of culture. The experiment was replicated three times, and data were analyzed using chi-square analysis. Washing of sperm in BoviPureTM had no effect (P\u3e.05) on either cleavage rate (77.2%) or blastocyst development (21.6%) when compared with controls (71.9% and 17.1%, respectively). These results indicate that, under conditions of our study, the washing of sperm with BoviPureTM did not significantly enhance the ability to produce bovine embryos in vitro

A Preliminary Report on the Frequency of Scrapie Susceptibility Alleles in Hampshire Sheep

Blood samples were collected from a total of 201 animals in five purebred Hampshire sheep flocks. DNA was isolated from the samples, and the protein-coding region of the prion protein gene was amplified using the polymerase chain reaction. The allelic frequencies of the prion protein codons 171 and 136 were determined. Results revealed that the codon 171 alleles Q, R, and H were present at frequencies of 72%, 27% and 1%, respectively. A subset of samples (n=48) was randomly selected for codon 136 genotyping. The codon 136 V allele, an allele not frequently observed in Suffolk sheep, was present in animals from three of five flocks at a frequency ranging from 7 to 33% of the animals tested within each flock. These data comprise the first report on the prevalence of scrapie susceptibility alleles in Hampshire sheep