Importance of Estrus Expression Before Fixed-time AIon Conception Rates in Beef Cattle

Expression of estrus prior to fixed-time AI has been reported to strongly impact overall pregnancy success. Behavioral estrus is a visual indicator that a cow or heifer’s internal environment is prepared for breeding. Insemination of a cow or heifer after estrus has been expressed will yield greater pregnancy success due to adequate uterine environment, increased fertilization rates, increased accessory sperm numbers, and increased overall embryo survival. It can be difficult to analyze the effects of estrus on pregnancy success across studies due to differences in number of animals and proportion of animals exhibiting estrus per study. In order to accurately analyze such data, a meta-analysis was used to place all studies on an equal level, thus, eliminating study bias. In the present study, a meta-analysis was conducted using data available on 10,116 beef cows and heifers in 26 studies that utilized the 5 most common fixed-time AI protocols to examine the effect of expression of estrus prior to insemination on conception rates. The overall model indicated a positive effect of estrus on conception rates with cows expressing estrus before fixed-time AI having greater conception rates compared with those not exhibiting estrus. There are also numerous management factors that can influence expression of estrus. Data were available on 547 cows that were synchronized with a CIDR based fixed-time AI protocol for estrus for 2 to 4 years. Analysis of these cows indicated that days postpartum did not impact estrus expression. In contrast, Body Condition Score (BCS) influenced estrus expression with cows in a BCS of ≤ 4 having decreased expression of estrus compared to those with a BCS \u3e 4. Initiation of estrous cycles before the breeding season also influenced estrus expression, with anestrous cows having greater expression of estrus compared with estrus-cycling cows. Fixed-time AI protocols offer producers the added benefit of reduced labor needed for heat detection, but the results of this study indicate the importance of detecting an animal in estrus prior to breeding. In conclusion, among all currently recommended fixed-time AI protocols, cows expressing estrus before fixed-time AI had improved conception rates, and BCS and estrus-cycling status had the greatest influence on expression of estrus

All-optical header processor for packet switched networks

A serial all-optical header processing technique is presented that is based on the two-pulse correlation principle in a SLALOM configuration. The operation is demonstrated using optical data packets with a packet header at 2.5 Gbit/s and Manchester encoded packet payload at 10 Gbit/s. Experimental evidence is provided in the case of two different output ports. A Bragg grating assisted all-optical header pre-processor based on self-phase modulation in a semiconductor optical amplifier is also presented. It is shown that the header pre-processor improves the performance of the SLALOM-based header processor and that the packet structure can be simplified

Optical flip-flop memory based on ring lasers sharing one active element with feedback through an extended cavity

We present a novel optical flip-flop configuration that consists of two unidirectional ring lasers with separate cavities but sharing the same active element unidirectionally. We show that in such a configuration light in the lasing cavity can suppress lasing in the other cavity so that this system forms an optical bistable element. Essential for obtaining the bistability is the presence of an additional feedback circuit that is shared by both lasers. We show experimentally that the flip-flop can be optically set and reset, has a contrast ratio of 40 dB and allows low optical power operation. We also present a model based on roundtrip equations. Good agreement between theory and experiments is obtained

1x2 optical packet switch using all-optical header processing

A 1×2 all-optical packet switch is presented. The header processing is implemented by using a SLALOM structure and an optical flip-flop memory is used to store the processed header bits. The packets are switched in wavelength by using cross-gain modulation. Experimental results are presente

The multicovering radius problem for some types of discrete structures

The covering radius problem is a question in coding theory concerned with finding the minimum radius $r$ such that, given a code that is a subset of an underlying metric space, balls of radius $r$ over its code words cover the entire metric space. Klapper introduced a code parameter, called the multicovering radius, which is a generalization of the covering radius. In this paper, we introduce an analogue of the multicovering radius for permutation codes (cf. Keevash and Ku, 2006) and for codes of perfect matchings (cf. Aw and Ku, 2012). We apply probabilistic tools to give some lower bounds on the multicovering radii of these codes. In the process of obtaining these results, we also correct an error in the proof of the lower bound of the covering radius that appeared in Keevash and Ku (2006). We conclude with a discussion of the multicovering radius problem in an even more general context, which offers room for further research.Comment: To appear in Designs, Codes and Cryptography (2012

Current status and prospects of photonic IC technology

The most complex photonic ICs today have been developed for WDM applications. An overview of the most important integration technologies will be given and recent developments towards broader applications and higher integration densities will be discussed