Low Line Research Articles

Effect of Polycarbosilane (PCS) on the High-Temperature Properties of Phenolic Resin (Phen) Films and Quartz Fiber/Phen-PCS Composites

In this study phenolic resin (Phen)-loaded PCS (Phen-PCS) films were prepared and quartz fiber/Phen-PCS composites based on the resin films were also prepared. The quartz fiber/Phen-PCS composites were prepared by impregnating 2.5 Dimension (2.5D was an arrangement of fibers) quartz fibers using the resin film infusion (RFI) process. The properties of the composites were investigated. The study demonstrated that the density of the composites, after curing gradually increased with the increase in PCS. The flexural strength of the composites exhibited a trend of increasing and then decreasing after curing and pyrolysis at 1100 °C under an N2 atmosphere. The flexural strength of the composites reached 13.73 MPa when the addition of PCS was 30% of the phenolic resin, representing an increase of 74.23% compared to that of the composites without PCS. The porosity was found to be as low as 2.3% after curing and 2.1% after pyrolysis. X-ray diffraction (XRD) analysis and infrared spectroscopy tests demonstrated that ceramicization products, such as SiO2 and SiC, were produced after pyrolysis of the composites containing PCS. This transformation significantly enhanced the ablation resistance of the composites. Butane flame tests were performed, and the lowest line and mass ablation rates were 0.026 mm/s and 0.196 mg/s after curing. The results of the study revealed the potential of PCS as a precursor to improve the mechanical properties and heat resistance of composites, which offers promising material options for high-temperature applications.

New regularization techniques for ill-conditioning problems and their applications: Choices of regularization parameters

This is a continued study of Li et al. (2011) for the regularization of ill-conditioning problems, where the minimal singular value σmin of discrete matrices is infinitesimal. To remove the effects of high frequency caused by the singular vector of σmin better, we combine the Tikhonov regularization (TR) with the truncated singular value decomposition (TSVD) (simply denoted by T-TR). New computational formulas of the traditional condition number (Cond) and the effective condition number (Cond_eff) are derived, and a brief error analysis is made. The regularization parameter λ is involved in the TR, and its better (or optimal) choices are essential in both theory and computation. For ill-conditioning problems, stability is more imperative than accuracy. The most important criterion is to reduce the Cond. Consider the linear algebraic equations Ax = b. The optimal regularization parameter for the TR is derived as λ=σmaxσmin, where σmax and σmin(>0) are the maximal and the minimal singular values of matrix A, respectively. The L-curve techniques emphasize the ill-conditioning of ‖xλ‖ (see Hansen (1998)). Note that the norm ‖xλ‖ is only part of the Cond in stability. In fact, by using regularization, the Cond may be greatly reduced, while the errors do not increase much. The second important criterion is for both stability and solution accuracy. The sensitivity index proposed in Zhang et al. (2021) indicates the severity of ill-conditioning via accuracy for comparing different numerical methods and techniques. The sensitivity index is effective not only to select the source nodes in the method of fundamental solutions (MFS), but also to select the regularization parameter in the TR. The regularization choices of the T-TR are similar to those of the TR because differences of the Cond and the errors between the TR and the T-TR are insignificant. Numerical experiments are reported by the MFS for Laplace’s equation, to support the new regularization techniques proposed. For data fitting, imaging processing, pattern recognition, and machine learning, the ‖xλ‖ is, however, more important than Cond for ill-conditioning. The L-curve techniques are used in wide applications, and discussed in Hansen (1998). The parameter choices are rather complicated if the crossover region is not small. In this paper, we apply the sensitivity index to L-curves, the optimal parameter λL−curve can be found by the minimal sensitivity index. The λL−curve may also be found by the lowest line that passes the origin. The new algorithms are simple and effective.

277 Phenotypic and genetic differences in Rambouillet lines divergently selected for reproductive rate over 50 years

Abstract A long-term selection experiment was conducted in a Rambouillet flock from 1969 to 2017. The high (HL) and low lines (LL) were divergently selected based on a maternal reproductive index, and an unselected control line (CL) was also maintained. Adult ewe traits considered were NLB, greasy fleece weight (GFW), and body weight after fall weaning of their lambs (BW). Results indicated that NLB was greatest for HL (1.67 ± 0.01), intermediate for CL (1.48 ± 0.02), and least for LL (1.28 ± 0.01; P < 0.001). Ewe GFW was greatest for LL (3.9 ± 0.02 kg; P ≤ 0.01) but not different between HL (3.82 ± 0.02 kg) and CL (3.88 ± 0.02 kg; P = 0.08); whereas, BW was least for HL (61.7 ± 0.19 kg; P ≤ 0.01) and not different between LL (62.9 ± 0.21 kg) and CL (62.6 ± 0.25 kg; P = 0.58). Heritability was estimated to be low for NLB (0.13 ± 0.02) and moderate for GFW (0.55 ± 0.03) and BW (0.46 ± 0.04). Genetic correlations were estimated to be near zero between NLB and GFW (-0.07 ± 0.08) and NLB and BW (0.12 ± 0.08) and low between GFW and BW (0.29 ± 0.06). Trends for NLB predicted breeding value differed among all 3 lines (P < 0.01) and was positive for HL (0.012 ± 0.0002 lambs/birth year), negative for LL (-0.005 ± 0.0002), and small but positive for CL (0.002 ± 0.0002). Inbreeding rates were positive in all lines but greatest for HL (0.45 ± 0.005 %/birth year), intermediate in LL (0.37 ± 0.006), and lowest in CL (0.28 ± 0.006). Results indicated long-term phenotypic selection for reproductive rate was effective and not genetically antagonistic with wool production or mature BW.

PENILAIAN KINERJA DI ERA COVID (Study Kasus di Dinas Sosial Provinsi Sulawesi Selatan)

9,278 lives have been lost. 130,538 patients are still struggling. However, 85,831 people have proven that sick because of the new type of Corona Virus or COVID-19 can be cured. (Liputan6.com). In Indonesia, there were 12,438 cases of Corona virus infection with 895 people dying and 2,317 declared. The World Health Organization (WHO) has paid special attention to the special policies of a number of countries that have begun to ease lockdowns or lockdowns in their territories. (Sindonews.com May 7, 2020). As a result of this pandemic, the life of the Indonesian economy has become devastated. The service and trade sectors have become stagnant. So that many of us see and read in the mass media, termination of employment to informal sector workers because production is hampered. The social impact caused by this pandemic has become a serious concern of the government by forming a task force. This task force coordinated by the social service distributed social assistance to people affected by the Covid 19 outbreak. In terms of distribution of distribution, social services have involved all lines of government starting from the lowest line, as well as reporting of results, also involving all areas of supervision, one of which is the inspectorate

Research on evaluation technology of gas anomaly zone in Xiadian Mine based on 3D seismic monitoring technology

ABSTRACT Based on the analysis of the theory of seismic exploration, this paper evaluates the quality of three-dimensional (3D) seismic data, analyzes the reflection characteristics of coal seam, and forecasts the thickness of coal seam qualitatively and quantitatively by using seismic attribute and wave group anti inversion method, and obtains the thickness plan of minable coal seam in Xiadian mine. According to the coal seam gas content and gas relative emission, it is predicted that the upper limit of gas relative emission in the mine will change from 1.38 to 20.30 m3/t·d, which is a low biogas mine area with high biogas area in some parts, and the destruction factors of No. 21 coal seam and No. 43 coal seam are abnormal in some parts, which are structural coal. The development of No. 21 coal seam is stable, with the thickness variation range of 0.5 ~ 12.5 m and the average thickness of about 4.3 m. The thickness of No. 43 coal seam is lower than that of No. 21 coal seam. The inversion thickness variation range is 0 ~ 4 m and the average thickness is about 2.5 m. The overall thickness of NO. 43 coal seam has little change. The gas anomaly area of No. 21 coal seam is mainly distributed in the form of dots, the lowest line of monoclinic structure and the monoclinic half slope are mainly distributed in two distribution belts in the form of dots, while the gas anomaly area of No. 43 coal seam is scattered with small area.

Effect of mid-line or low-line milking systems on lipolysis and milk composition in dairy goats

AbstractTwo experiments were carried out to investigate how milking in mid-line (ML) affects the lipolysis level and milk composition in goat livestock, in comparison with low-line (LL) milking. The first experiment took place, in triplicate, on an experimental farm. For each replicate, a crossover design (62 goats, two treatments, ML and LL, in two periods each lasting 4 days) was used. Milk samples were taken daily at 0 and 24 h after milking. In the first experimental replicate, some enzymatic coagulation cheeses were made, which were assessed by a panel of tasters at 50 and 100 days of maturation. In the second experiment, the lipolysis level and composition of tank milk from 55 commercial dairy goat farms (25 ML and 30 LL) were analysed, in milk samples taken in three different weeks. The results of the first experiment showed that ML milking increased free fatty acid (FFA) concentration in raw goat's milk significantly (0.71 v. 0.40 mmol/l, respectively). However, in the milk samples taken from commercial farms the FFA concentration remained unaffected by the milking pipeline height (0.59 v. 0.58 mmol/l for ML and LL, respectively). No significant differences were found in the milk composition, nor in the sensory characteristics in the cured cheeses, which suggests that factors other than the milkline height are able to influence the level of lipolysis under commercial conditions. Therefore, ML milking should not be discouraged, provided that the correct functioning and management of the milking operation and milk storage on the farm is guaranteed.

DETERMINATION OF MATERNAL ANTIBODY (IGY) CONCENTRATION AS A GENETIC MARKER TO IMPROVE FERTILITY, HATCHABILITY AND LIVABILITY PERCENTAGES IN TWO LOCAL STRAINS OF CHICKENS

The present study was carried out at the Department of Poultry and Fish Production, Faculty of Agriculture at Shibin El-Kom, Menoufia University. The aim of the present study was to determine the concentrations of maternal antibody (IgY) in blood serum of layers and hatched chicks, in addition to egg yolk of three, control, high and low IgY antibody lines of Sinai and Silver Montazah local strains of chickens as a genetic marker to improve fertility, hatchability and livability percentages. The results were summarized as follows: 1. Sinai strain had significantly higher IgY antibody concentration than Silver Montazah strain of chickens, being 4.68 vs 4.22 mg/ml in hen blood serum, 4.11 vs 3.46 mg/ml in egg yolk, 3.09 vs 2.66 mg/ml in hatched chicks serum and 48.00 vs 38.41 mg/egg yolk total, respectively. 2. Highly significant differences (P<0.01) among lines, the high (LH) lines harvested the highest IgY level and control line (CL) occupied intermediate level, whereas the low lines (LL) had the lowest IgY level in both strains of chickens. The means of IgY concentrations were 3.74, 6.15 and 2.44 mg/ml in Silver Montazah strain, where the corresponding values in Sinai strain were 4.63, 6.65 and 2.47 mg/ml for control, HL and LL lines, respectively. 3. The high IgY antibody lines had significant (P < 0.05) higher percentages of fertility than the control and low IgY antibody lines. The averages of fertility percentages were 76.97 vs 77.21 for control lines, 85.29 vs 88.19 for high lines and 68.38 vs 68.81 for low lines of Silver Montazah and Sinai strains of chickens, respectively. 4. The means of hatchability percentages of fertile eggs were 72.32% vs 77.60% for Silver Montazah and Sinai chickens, respectively. Also, means of hatchability percentages were 89.18 vs 91.89% for high lines, 75.11 vs 77.65% for control lines and 57.07 vs 61.33% for low lines of Silver Montazah and Sinai strains of chickens, respectively. 5. Sinai chickens had significantly (P < 0.5) higher livability (%) as compared to Silver Montazah chickens (80.65 vs 75.14%) due to the direct action of maternal antibody (IgY) transferred from layers to newly hatched chicks. 6. High IgY lines had significantly (P < 0.5) higher percentages of livability at 28d. The means of livability (%) were 75.83 vs 80.91 (%) for control lines, 87.92 vs 93.49 (%) for high lines, and 65.29 vs 65.79 (%) for low lines of Silver Montazah and Sinai strains of chickens, respectively. 7. Since the high IgY antibody improved fertility, hatchability and viability, So that, the IgY can be used as a genetic marker to improve some productive traits in chickens.

Thickness and tension of the gluteal aponeurosis and the implications for subfascial gluteal augmentation

The aim of this study is to elucidate the thickness and tension of the gluteal aponeurosis (GA) as related to subfascial gluteal augmentation. Twenty buttocks from 10 Korean fresh cadavers (age range: 69-92 years, five men and five women) were dissected. Five radial lines were made from the greater trochanter (GT) to the highest point of origin of the gluteus maximus muscle (GM), the posterior inferior iliac spine (PSIS), the piriformis line (P), the coccyx (Co) and the ischial tuberosity (IT). The upper four lines were intersected by three curvilinear lines that divided them by a quarter, half and three-quarters ratios, and the lowest line was divided by a third ratio and a two-thirds ratio. At the 14 intersecting points, the force needed to break the 6 mm width of the GA was measured. The thickness of the GA was also measured with a digital caliper. The GA was widest at the GT-Co line (161.7±15.8 mm), and it was narrowest at the GT-IT line (106.5±21.2 mm). At most of the points (12 among the 14 points), the breaking strength of the GA was greater than 20 Newtons (N). The breaking strength of the GA did not vary significantly according to the locations (P=0.568, anova). The breaking strength of the males (22.8±6.6 N) was significantly greater than that of the females (20.3±7.5 N, P=0.003, t-test). The thickness of the GA varied according to the locations (0.4±0.2 mm to 0.7±0.3 mm). The thickness of the GA of the upper part (GT-GM line: 0.64±0.24 mm; GT-PSIS line: 0.66±0.23 mm; GT-P line: 0.66±0.24 mm) was significantly greater (P=0.040, 0.017, 0.018, respectively) than that of the lower part (GT-IT line: 0.49±0.18 mm). The GA of the males (0.70±0.23 mm) was significantly thicker than that of the females (0.53±0.21 mm, P<0.001, t-test). We conclude that the GA is capable of holding gluteal implants in the proper position, as the average force to break up the 6 mm width of the GA in females was greater than 20 N.

A New Spin on the Vestibular Test Battery: Dynamic Visual Acuity and Subjective Visual Vertical

A New Spin on the Vestibular Test Battery: Dynamic Visual Acuity and Subjective Visual Vertical

Laser Cutting Layout Based on Particle Swarm Optimization and Graphic Interference Detecting

Laser cutting of thin metal parts involves packing 2-D arbitrary objects into rectangle work space. The problem is shown to be NP-complete. This paper presents a novel approach to solve the problem, by dividing the problem into 2 parts. The first part finishes packing minimum envelop rectangles of the objects by applying Particle Swarm Optimization (PSO) with the lowest line packing as its fitness function. The second part moves the objects to a most suitable place by detecting interference with neighbor objects. A complete interference detection method between two polygons, either convex or concave has been suggested. In addition, two approaches, both the scanning approach and the circumcirlcle approach, have been developed to find the neighbor objects of the current moving object. And the order to move the objects has also been found in a scanning manner. Computational experiments have been carried out both for the first and the second part and the results are inspiring.

Genetic description of a divergent selection experiment in Angora rabbits with overlapping generations

The chief aims of this paper were the following: (i) to describe the demography and genetic structure in two divergent selected lines for total fleece weight (TFW) of French Angora rabbits with overlapping generations; (ii) to describe the effects of inbreeding during an experiment of divergent selection. A study of longevity with the survival kit showed that there was no significant difference in the risk of death or culling between the low line (LL) and high line (HL). A significant effect of inbreeding (p < 0.05) was observed with a 30% higher risk factor in the highest class of inbreeding coefficient compared with the other classes. The means of generation interval were 562 and 601 days in LL and HL, respectively. The numbers of generations for LL and HL were 3.90 and 3.64, respectively. Generation intervals decreased significantly from 1995 to 2000 (p < 0.05). The number of daughters in HL was very variable. The number of animals per generation was higher in HL than in LL. Each buck left nearly three daughters to the next generation (2.52 in LL, 3.24 in HL). In both lines, the effective number of ancestor genomes still present in the genetic pool of the generation was around eight from the reference population of 1995 to that of 2001. Inbreeding in HL was always higher than in LL. The effect of inbreeding was also significant (p < 0.05) on TFW and live weight. The animals with the lowest inbreeding category produced a higher TFW (p < 0.05) than the others. The observed selection differentials were lower than that expected owing to the breeding animal management rules in order to control inbreeding increase.

Collaborator of Stat6 (CoaSt6)-associated Poly(ADP-ribose) Polymerase Activity Modulates Stat6-dependent Gene Transcription

The transcription factor Stat6 plays a critical role in interleukin-4-dependent gene activation. To mediate this function, Stat6 recruits canonical transcriptional co-activators including the histone acetyl transferases CREB-binding protein and NCoA-1 and other proteins such as a p100 co-factor. However, much remains unknown regarding the constituents of Stat6 enhancer complexes, and the exact molecular events that modulate Stat6-dependent gene activation are not fully understood. Recently, we identified a novel co-factor, CoaSt6 (collaborator of Stat6), which associates with Stat6 and enhances its transcriptional activity. Sequence homologies place CoaSt6 in a superfamily of poly(ADP-ribosyl)polymerase (PARP)-like proteins. We have demonstrated here that PARP enzymatic activity is associated with CoaSt6, and this function of CoaSt6 can append ADP-ribose to itself and p100. Further, we show that a catalytically inactive mutant of CoaSt6 was unable to enhance Stat6-mediated transcription of a test promoter. Consistent with these findings, chemical inhibition of PARP activity blocked interleukin-4-dependent transcription from target promoters in vivo. Taken together, we have identified a CoaSt6-associated PARP activity and provided evidence for a role of poly(ADP ribosyl)ation in Stat-mediated transcriptional responses involving a novel PARP.

Evolution of Hard X‐Ray Spectra along the Orbital Phase in Circinus X‐1

Using the data from the Proportional Counter Array and the High-Energy X-Ray Timing Experiment on board the Rossi X-Ray Timing Explorer satellite, we investigate the evolution of the 3-200 keV spectrum of the peculiar low-mass X-ray binary Circinus X-1 along its orbital phase. A power-law hard component, dominating above ~30 keV as well as contributing between 0.9% and 3.5% of the total flux, and the iron emission line are detected in the spectrum. It is found that the derived photon index (Γ) of the power-law hard component and the characteristics of the iron emission line are modulated by the orbital phase: the hardest hard tail, the lowest line energy, and the largest line width of the iron emission line are detected at the periastron. However, the softest hard tail, the highest line energy, and the lowest line width of the iron emission line are detected after the apastron. At the periastron the source evolves along a complete track in the color-color diagram. These behaviors of orbital modulation are discussed. A possible origin of the power-law hard component is also discussed.

Gene effect and combining abilities for plant height and head diameter in sunflower

Plant height and head diameter are important parameters which effect on a yield in sunflower. Six restorer Rf lines, three tester A lines and their 18 Fl hybrids were studied, using line x tester method. Significant differences were found between restorer lines and testers and their Fl hybrids for plant height and head diameter. Regarding the inheritance of examined characteristic, super dominance and dominance of better parent occurred, and the intermediary too. Tester line HA-48A (188.25 cm) and Fl hybrid HA-48A x RHA-SELEUS (245.10 cm) had the highest mean value for plant height, and the lowest value had line RHA-BRE-1 (105.35 cm) and hybrid L-19A x RHA-BRE-1 (147.9 cm). For head diameter, the highest mean value had line L-19A (19.02 cm) and Fl hybrids HA-48A x RHA-TR-20 and L-19A x RHA-TR-20 (24.55 cm), and the lowest line RHA-BRE-1 (13.10 cm) and hybrid HA-26A x RHA-M-72 (20.25 cm). Based on the results, the following conclusion is that lines RHA-BRE-1 for plant height and RHA-SELEUS for head diameter have the best GCA, and the best SCA have hybrids L-19A x RHA-BRE-1 for plant height and HA-26A x RHA-SELEUS for head diameter. Analyzing components of genetic variance, the nonadditive component played the main role in the inheritance of plant height and the additive of head diameter. The largest average contribution in the expression of plant height had the tester A-lines (83.17%) and for head diameter Rf lines had the greatest influence (58.13%).

Liner schemes of the aluminum damascene interconnection for sub-0.2 μm line pitch metallization

We investigate the effects of liner scheme on the line and via resistances of aluminum damascene interconnects. The lowest line (∼0.19 Ω/sq. at 0.20 μm trench width) and via (∼0.5 Ω/via at 0.35 μm diameter) resistances are obtained at each different liner schemes of 30 nm TiN/20 nm Ti and 50 nm Ti-only, respectively. An optimized liner scheme of 10 nm TiN/40 nm Ti is therefore proposed. This scheme minimizes the TiAl 3 formation due to the interfacial reaction between the Al and the TiN, and produces the most satisfactory resistances of the line (∼0.24 Ω/sq. at 0.2 μm trench width) and the via (∼0.9 Ω/via at 0.35 μm diameter), respectively.

A Metal‐poor Compact HiiRegion with a Small, Isolated, and Dense Young Stellar Cluster

IRAS 04000+5052 appears to be a single, somewhat extended red source on optical CCD images. From our infrared imaging observations, an infrared cluster consisting of 15 objects is discovered in this region. In this paper, by discussing and analyzing the observational results of near-infrared imaging, optical spectroscopy, and the 12CO molecular line, together with IRAS and NRAO VLA Sky Survey (NVSS) data, we conclude that IRAS 04000+5052 is a compact H II region with a very young dense stellar cluster. The spectrum of the compact H II region shows that it is a metal-poor nebula, which has the lowest line ratio of [N II]/Hα (~1/16.3) discovered in the H II regions of our Galaxy until now. There are three possible explanations. The first is a Herbig Be star model, the second suggests that the material constituting this nebula could come from some nearby external galaxy from accretion of galaxies, and the third suggests that the material was produced in the primeval phase of our Galaxy and has not been chemically contaminated much. There exists an undetected gap between K = 13.6 and the detection limit of 16.2 mag. We give two possible interpretations for this undetected gap; one is based on the star formation itself, and the other is a possible observational effect. This infrared cluster is a very small (0.83 pc × 1.55 pc ) and isolated high-mass protostellar cluster, in which there is a B0.5-type star exciting the compact H II region. The derived heliocentric distance (~4.29 kpc) of IRAS 04000+5052 is twice as large as that of the Perseus arm. It is located far beyond the Perseus arm at the direction (l = 150.86).

Selection for High and Low Threshold Body Weight at First Egg in Broiler Strain Females. 6. Threshold Weight for Onset of Photosensitivity in Females of the Selection Lines

A two-way selection program, carried out for high and low threshold BW at onset of lay (TWL) resulted in a marked difference in TWL in the selected lines. Later studies showed that the selection procedure had decreased photoperiodic drive in the high line (HL) as compared to the low line (LL), in this way increasing the number of days required from onset of photosensitivity to onset of lay in the HL as compared to the LL. The present study was carried out to determine whether the difference in photoperiodic drive was sufficient to account for the entire difference in TWL between the HL and LL, or whether it is also necessary to postulate a difference in threshold weight for onset of photosensitivity (TWSM) as well. Birds of the two lines were raised under feed restriction to 22 wk reaching weights (1,881.8 g for LL, 2,034.8 g for HL), well below anticipated TWSM. They were then provided gradually increasing amounts of feed, resulting in daily gains of 3 to 5 g for the LL and 8 to 9 g for the HL. Under this regimen, the HL entered lay an average of 64.4 d later and at a body weight 752.8 g greater than the LL. On the basis of previous studies of these lines, of the 64.4 d delay in onset of lay in the HL as compared to LL, 21 d can be attributed to the difference in photoperiodic drive. The excess of 43 d must thus represent a difference in TWSM. During this period the HL were gaining about 8.5 g/d, and at 22 wk HL body weight was already 153 g greater than LL body weight. In all then, TWSM of HL is estimated at 518 g greater than that of the LL. Thus, the selection procedure employed for TWL apparently affected TWSM as well as photoperiodic drive.

Resonance Raman spectrum and excitation profile of mass-selected zirconium trimers

We present the resonance Raman and Raman excitation profile of mass-selected zirconium trimers in argon matrices. In the Raman spectra, two fundamentals and one overtone are observed. Average Raman shifts, along with standard deviations (in parentheses) are 176.7 (13) cm−1 (ν2), 258.0 (12) cm−1 (ν1), and 516.1 (8) cm−1 (2ν1). The ratio of the frequencies of the two lowest lines (ν1/ν2) is 1.46, which is very close to √2. This is indicative of a symmetrical equilateral geometry (D3h). In such a case we expect two normal frequencies, one for a totally symmetric stretch of symmetry a′1 (ν1) and a doubly degenerate bend of symmetry e′(ν2). The Raman excitation profiles of the ν1(a′1) line shows two broad maxima: one near 491 nm and the other near 614 nm. The ν2 (e′) profile shows a broad region of intensity only near 614 nm. With the aid of theory we assign the 614 nm band to be 1A′1−1E′ (x,y polarized) while the 491 nm band must be 1A′1−1A″2 (z polarized).

Two-Way Selection for Threshold Body Weight at First Egg in Broiler Strain Females.: 5. Replication of Results in a Two-Generation Selection Experiment

Selection for high and low threshold weight for onset of lay (ThrWtLay), carried out in a broiler line over six generations, was previously found to increase reproductive performance in the low line (LL). Because of the potential importance of this effect, a two-generation replication of the original experiment was carried out using a modern broiler line. Selection was on the basis of ThrWtLay, measured as body weight at first egg, following gradual release from feed restriction. The total response to selection over two generations was 382 g, giving a realized heritability of .42. The difference in 6-wk body weight of the two lines was +19 g in favor (P > .05) of the high line (HL). Reproductive performance was measured in the S2 generation and in the first (R1) generation of relaxed selection. On the average, age at first egg of LL was 17.6 d earlier, and prepeak, postpeak, prepeak, postpeak, and total egg production of LL to a fixed age was 9.9, 1.1, and 11.1 eggs greater, respectively, than that of HL. The differences in age at first egg, prepeak, and total egg production were significant; those in postpeak production were not. There was a difference of 1.1 g in favor (P > .05) of HL for egg weight. Thus, the results of this short-term selection experiment are broadly consistent with those of the original, long-term selection. Namely, ThrWtLay responded strongly to selection, with a powerful accompanied response in age at onset of lay and in prepeak egg production, and only a small effect on 6-wk body weight. However, in contrast to the results obtained previously, LL in the present experiment showed only a small increase (P > .05) in postpeak production relative to HL. Nevertheless, although an effect on postpeak production was not obtained in the present experiment, the results do provide general support for the previously expressed view that selection for early onset of lay, on release from feed restriction, may provide a means of increasing photoperiodic drive and consequent reproductive performance of broiler breeders.

Selection for High and Low Threshold Body Weight at First Egg in Broiler Strain Females.: 4. Photoperiodic Drive in the Selection Lines and in Commercial Layers and Broiler Breeders

A two-way selection program, carried out for high and low threshold BW at onset of lay (ThrWtLay), decreased photoperiodic drive of the high line (HL) relative to the low line (LL). Photoperiodic drive in modern broiler breeder females was compared to layer females in experiments using the HL and LL lines, a commercial layer cross (LX), and a commercial broiler breeder female line cross (BX). Treatment groups were: NS, natural decreasing light to 20 wk, followed by natural light supplemented to 16 h daily with artificial light; NN, natural decreasing light to end of experiment; DD, dark room from hatch to end of experiment; ND, natural decreasing light to 20 wk, dark room thereafter. Under NS, mean age and BW at first egg was greater for the HL line than for the LL line. The difference increased by a further 8.9 d and 217.5 g under NN. Similarly, under NS, mean age and BW at first egg was greater for BX than for LX, and the difference increased by a further 22.6 d and 256.1 g under NN. These interactions indicate greater photoperiodic drive of LX and LL stocks relative to the HL and BX stocks. Prepeak and peak egg production (EP) was greatest for the LX, lower for the LL, and lower yet for HL and BX. Photoperiodic drive may be of major importance in determining prepeak and peak EP. Except for the DD treatment, age and BW of the LX cross at first egg were virtually identical across treatments, those of the LL line were similar, whereas those of the HL and BX stocks showed differences. Similarly, EP curves of the LX cross were virtually identical across treatments, those of the LL line were relatively uniform, but those of the HL and BX stocks again showed great differences. Standard deviation and coefficient of variation of peak EP were very low for the LX cross, still low, but significantly greater for the LL line, and significantly greater yet again for both HL and BX stocks. Thus, increased photoperiodic drive may also be associated with greater stability of reproductive performance. Selection for early onset of lay on release from feed restriction may provide a means of increasing photoperiodic drive and consequent reproductive performance of broiler breeders.