Electromagnetic wave propagation in rain and polarization effects

This paper summarizes our study on microwave and millimeter-wave propagation in rain with special emphasis on the effects of polarization. Starting from a recount of our past findings, we will discuss developments with these and how they are connected with subsequent research

mechanism of emulsion polymerisation of butadiene-styrene with "redox recipes"

Applied Science

Early weaning in Northern Great Plains beef cattle production systems: II. Development of replacement heifers weaned at 80 or 215 d of age

Studies were conducted to evaluate effects of weaning and subsequent heifer development treatments within two herds located in the Northern Great Plains, USA. Heifer calves from predominantly Angus x Hereford dams were stratified within damage and calving date (Fort Keogh Livestock and Range Research Laboratory (LARRL), Miles City, MT, USA; n=328) and randomly assigned within study and strata to one of three weaning treatments. Heifer calves from Angus and Angus x Simmental dams (n=167; Judith Gap (JG),MT,USA) were stratified within breed group by age, calving date, and AI sire. Heifer calves either remained with their dams until time of normal weaning (NW; approximately 213 d of age) or were early weaned (approximately 80 d of age) on to one of two early weaning (EW) diets. Heifer calves assigned to EW treatments received one of the following diets: (1)17.5% CP (69% RDP and 7.53 MJ/kg NEm or (2) 17.5% CP (57% RDP and 7.69MJ/kg NEm). At the time of normal weaning, heifers from LARRL (2005 and 2006) were further divided into two heifer development (HD) diet treatments that differed only in proportion of RDP: (1) 12.5% CP (83% RDP and 6.28MJ/kg NEm); or (2) 12.5% CP (72% RDP and 6.28MJ/kg NEm). Heifers from JG were fed a common heifer development diet. Heifer BW at time of normal weaning revealed that EW heifers were heavier, regardless of type of protein delivered by EW treatments (P\u3c0.10). Heifer BW at the end of the development period was greater for EW heifers at LARRL (P\u3c0.01) and similar for JG heifers (P=0.35) regardless of weaning treatment. Heifers at LARRL that received EW treatments had a greater percentage pubertal (P\u3c0.06) from 39 to 2 d before breeding compared to NW heifers. Pregnancy rates were not influenced by early weaning or heifer development treatments at LARRL (P\u3e0.05); however, a greater percentage of EW heifers became pregnant throughout the breeding season at JG (P=0.03). These experiments demonstrate early weaning is a viable option to develop and breed heifers in extensive beef production systems in the Northern Great Plains, USA. When production may be jeopardized by environmental conditions (e.g., drought), early weaning calves will not impair a heifers opportunity to be retained as replacement females as early weaned heifers have similar or greater reproductive success than heifers that are normal weaned

Early weaning in Northern Great Plains beef cattle production systems: I. Performance and reproductive response in range beef cows

A study was conducted to determine if early weaning spring born calves can be an alternative management strategy during drought and if early weaning facilitates rebreeding of young cows. Our objectives were to determine effects of early weaning at the start of breeding on cow body weight, body condition score, and reproductive performance with or without estrous synchronization and AI in two herds in the Northern Great Plains, USA. In Exp.1and 2, crossbred cows were stratified within cow age by postpartum interval, and calf sex, and were assigned within strata to one of two weaning treatments at the start of breeding when calves averaged 80-d of age: (1) early weaned (permanent calf removal); or (2) no weaning (calves suckled cows until normal weaning approximately 210-d of age). Cows in Exp.1 were exposed to natural service whereas cows in Exp.2 were exposed to estrous synchronization for AI using a CIDR for 7 d with GnRH at CIDR insertion and PGF2α at CIDR removal followed by natural service. In Exp.3, cows were stratified within breed by age, postpartum interval, calf sex, and AI sire and were assigned within strata to one of two weaning treatments at the start of breeding, as described for Exp.1and 2. Estrous cycles of all cows were synchronized for AI using one of two protocols including 14 d CIDR + PGF2α 16 d following CIDR removal (primiparous cows) or a CIDR insert for 7 d with GnRH at CIDR insertion and PGF2α at CIDR removal (multiparous cows). Cows in Exp.2 and 3 were bred by AI approximately 12 h after observation of estrus or by timed AI at 80 h after PGF2α concurrent administration of GnRH. Artificial insemination (Exp.2), breeding season pregnancy rate, and day of conception was not influenced (P\u3e0.10) by weaning treatment for Exp.1and 2. However, early weaned cows in Exp.3 had 12.0% greater (P=0.03) AI pregnancy rates and conception occurred 3.78 d earlier (P=0.03) than normal weaned cows. At the time of normal weaning, cows that had their calves removed at early weaning were heavier and had greater body condition (P\u3c0.01)than normal weaned cows in each experiment. We conclude that early-weaning beef cows at the start of the breeding season improved BW gain and BCS allowing those females to enter winter in greater BCS then NW cows, but improvements in reproductive performance were inconsistent

De fabricage van sorbitol

Document(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science

Vertical Ownership, Program Network Carriage, and Tier Positioning in Cable Television: An Empirical Study

Vertical integration, Cable television, Program carriage, Program positioning,