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This paper investigates properties of polar-polar concatenated codes and their potential applications. We start by reviewing previous work on stopping set analysis for conventional polar codes, which we extend in this paper to concatenated architectures. Specifically, we present a stopping set analysis for the factor graph of concatenated polar codes, deriving an upper bound on the size of the minimum stopping set. To achieve this bound, we propose new bounds on the size of the minimum stopping set for conventional polar code factor graphs. The tightness of these proposed bounds is investigated empirically and analytically. We show that, in some special cases, the exact size of the minimum stopping set can be determined with a time complexity of O(N), where N is the codeword length. The stopping set analysis motivates a novel construction method for concatenated polar codes. This method is used to design outer polar codes for two previously proposed concatenated polar code architectures: augmented polar codes and local-global polar codes. Simulation results with BP decoding demonstrate the advantage of the proposed codes over previously proposed constructions based on density evolution (DE). 

Optimization of growth performance and fat metabolism in broilers are critical for meat quality and overall production efficiency. This experiment investigated the effects of dietary baicalein supplementation and embryonic heat conditioning (EHC) on the growth performance and adipose tissue metabolism of 10-day old broilers. Fertile eggs were divided into control and EHC groups, with EHC eggs exposed to intermittent heating (39.5 °C) from day 7 to day 16 of incubation. Hatched chicks were further divided into four groups: CC (control control), CT (control treatment with baicalein), EC (embryonic heat control), and ET (embryonic heat treatment with baicalein), and were fed ad libitum. On day 10 post-hatch, blood and adipose tissue samples were collected for analysis. C/EBPα mRNA was lower in the ET group compared to the EC group and higher in the CT group compared to the CC group. PPARγ and HSL mRNAs were elevated in both the ET and CT groups relative to their controls. Additionally, plasma non-esterified fatty acid (NEFA) levels were significantly higher in the CT group compared to the CC group. These results indicate that baicalein supplementation, particularly when combined with embryonic heat conditioning, can modulate fat metabolism and potentially improve the growth performance of broilers, thereby offering insights into strategies for enhancing poultry production. 

IntroductionExposure to elevated temperatures during incubation is known to induce epigenetic changes that are associated with immunological and stress-response differences at a later age. Reports on its effects on the adipose tissue are still scarce. In this experiment, we investigated the effect of embryonic heat conditioning (EHC) on growth, adipose tissue mRNA and global DNA methylation in broiler chicks at day 4 post-hatch. MethodsFertile eggs were divided into two groups: control and EHC. Eggs in the control group were incubated at 37.8°C and 80% relative humidity from day 0 to day 18.5 (E0 to E18.5). The EHC eggs were subjected to an intermittent increase in temperature to 39.5°C and 80% relative humidity from E7 to E16 for 12 h (07:30–19:30) per day. On day 4 post-hatch, control and EHC chicks were subjected to 36°C using three time points: 0 (no heat challenge serving as the control), and 2 and 12 h relative to start of the heat challenge. Fifteen chicks were sampled from each group for every timepoint. Body weight was recorded before euthanasia and subcutaneous adipose tissue was collected. ResultsBody weights were similar in control and EHC groups. Diacylglycerol O-acyltransferase 2 (DGAT2) mRNA was lower in the EHC group at time 0 relative to control. Hormone-sensitive lipase (HSL) mRNA was greater in the EHC than control group at the 0 h timepoint. Heat challenge affected adipose tissue DNA methylation, with methylation highest at 12 h into the heat challenge. DiscussionThese findings highlight the dynamic molecular responses of chicks to heat stress during early post-hatch development and suggest that EHC may affect heat stress responses and adipose tissue development through mechanisms involving lipid remodeling and DNA methylation.