Removing data and using metafounders alleviates biases for all traits in Lacaune dairy sheep predictions

Bias in dairy genetic evaluations, when it exists, has to be understood and properly addressed. The origin of biases is not always clear. We analyzed 40 yr of records from the Lacaune dairy sheep breeding program to evaluate the extent of bias, assess possible corrections, and emit hypotheses on its origin. The data set included 7 traits (milk yield, fat and protein contents, somatic cell score, teat angle, udder cleft, and udder depth) with records from 600,000 to 5 million depending on the trait, ～1,900,000 animals, and ～5,900 genotyped elite artificial insemination rams. For the ～8% animals with missing sire, we fit 25 unknown parent groups. We used the linear regression method to compare “partial” and “whole” predictions of young rams before and after progeny testing, with 7 cut-off points, and we obtained estimates of their bias, (over)dispersion, and accuracy in early proofs. We tried (1) several scenarios as follows: multiple or single trait, the “official” (routine) evaluation, which is a mixture of both single and multiple trait, and “deletion” of data before 1990; and (2) several models as follows: BLUP and single-step genomic (SSG)BLUP with fixed unknown parent groups or metafounders, where, for metafounders, their relationship matrix gamma was estimated using either a model for inbreeding trend, or base allele frequencies estimated by peeling. The estimate of gamma obtained by modeling the inbreeding trend resulted in an estimated increase of inbreeding, based on markers, faster than the pedigree-based one. The estimated genetic trends were similar for most models and scenarios across all traits, but were shrunken when gamma was estimated by peeling. This was due to shrinking of the estimates of metafounders in the latter case. Across scenarios, all traits showed bias, generally as an overestimate of genetic trend for milk yield and an underestimate for the other traits. As for the slope, it showed overdispersion of estimated breeding values for all traits. Using multiple-trait models slightly reduced the overestimate of genetic trend and the overdispersion, as did including genomic information (i.e., SSGBLUP) when the gamma matrix was estimated by the model for inbreeding trend. However, only deletion of historical data before 1990 resulted in elimination of both kind of biases. The SSGBLUP resulted in more accurate early proofs than BLUP for all traits. We considered that a snowball effect of small errors in each genetic evaluation, combined with selection, may have resulted in biased evaluations. Improving statistical methods reduced some bias but not all, and a simple solution for this data set was to remove historical records.     

一种基于实时几何测距的船桥主动防撞方法

本文提出一种基于实时几何测距的船桥主动防撞方法。该方法对船的改动量甚微,仅需维持多项距离矩阵,通过告警逻辑矩阵进行展示与告警,能起到很好的船桥防撞提示效果。     

Dependence of mechanical and tribological performance on the microstructure of (CrAlTiNbV)Nx high-entropy nitride coatings in aviation lubricant

The (CrAlTiNbV)N_x coatings are fabricated by controlling the substrate bias via magnetron sputtering method. Under low substrate bias, the coating tends to form a loose columnar crystal structure with (200) preferred orientation. However, when the substrate bias increases, the coating transforms into a dense nanocrystalline structure, and the (111) orientation is enhanced. As the substrate bias increases, the residual stress and hardness of the coating gradually increase, while the adhesion strength decreases slightly. Friction tests show that the coating possesses the lowest average friction coefficient (about 0.06) and wear rate (8.7 × 10^-9 mm³/N·m) in 4050# aviation lubricant, which is achieved under the substrate bias of -96 V and -126 V, respectively.     

Ferroelectric and electromechanical performance of diverse engineered states of Mn-doped 0.75Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 ceramics

The materials processing history has a great influence on their properties and finally determines their application effect. In this paper, the ferroelectric, polarization-switching current, and strain properties of Mn-doped 0.75Pb(Mg_1/3Nb_2/3)O₃-0.25PbTiO₃ ceramics were studied in fresh state, aged state, and poled state, respectively. Compared with the symmetric polarization-electric-field (P-E) hysteresis loops, current-density-electric-field (J-E) curves, and bipolar electric-field-induced strain (S-E) curves in fresh state samples, asymmetric P-E loops, J-E curves, and bipolar S-E curves were obtained in poled state samples. Well-aged-state samples exhibit double hysteresis P-E loop, four peaks J-E curves, and symmetric S-E curves without negative strain. The symmetry-conforming short-range order (SC-SRO) principle of point defects and internal electric field E_i is employed to clarify the different phenomenon of three states. Results indicated that randomly oriented defect polarization P_D in aged samples can reverse the spontaneous polarization P_S back and result in the double hysteresis P-E loop and four peaks J-E curves. The oriented P_D and resulting E_i in poled-state samples will lead to the asymmetric loops and strain memory effect.     

A Case of Double Standard: Sex Differences in Multiple Sclerosis Risk Factors

Multiple sclerosis is a complex, multifactorial, dysimmune disease prevalent in women. Its etiopathogenesis is extremely intricate, since each risk factor behaves as a variable that is interconnected with others. In order to understand these interactions, sex must be considered as a determining element, either in a protective or pathological sense, and not as one of many variables. In particular, sex seems to highly influence immune response at chromosomal, epigenetic, and hormonal levels. Environmental and genetic risk factors cannot be considered without sex, since sex-based immunological differences deeply affect disease onset, course, and prognosis. Understanding the mechanisms underlying sex-based differences is necessary in order to develop a more effective and personalized therapeutic approach.     

焊缝表面缺陷激光扫描三维重构测量

为检测工件焊缝表面缺陷，采用点激光位移传感测距法和数据拟合技术进行焊缝表面缺陷检测试验研究. 首先采集缺陷表面轮廓数据点，利用高斯滤波对原始数据降噪处理. 再对处理后的数据点进行Delaunay三角剖分，使散乱点连接并结合其空间坐标重构出缺陷的三维模型. 结果表明，基于点激光位移传感测距技术及焊缝表面缺陷三维重构方法可以准确判断焊缝成形情况.     

脉冲偏压对TiAlCN薄膜结构与力学性能的影响

利用多弧离子镀-磁控溅射复合技术通过改变脉冲偏压在Si片与SS304基体表面制备了TiAlCN薄膜,研究了不同脉冲偏压对薄膜结构和力学性能的影响。薄膜成分、表面形貌、相结构及力学性能分别利用能量弥散X射线谱(EDS)、扫描电镜(SEM)、X射线衍射(XRD)和纳米压痕仪等设备进行表征。结果表明,随着脉冲负偏压的增加,薄膜中Ti元素的含量先减小后增大,而Al元素有相反的变化趋势。适当增大脉冲偏压,薄膜表面颗粒、凹坑等缺陷得到明显改善。物相分析表明TiAlCN薄膜主要由(Ti,Al)(C,N)相,Ti4N3-x相和Ti3Al相组成。薄膜平均硬度与弹性模量随脉冲负偏压的增加先增大后减小,在负偏压-200 V时达到最大值分别为36.8 GPa和410 GPa。     

Negative magnetization and exchange bias effect in Fe-doped CoCr2O4

Polycrystalline ceramics of Co(Cr_1-xFe_x)₂O₄ (0?≤?x?≤?0.12) were experimentally studied based on a series of temperature and time-dependent dc magnetic measurements using different magnetic field histories. Magnetization in field cooling process was continuously decreased for doping content x in the range of 0?≤?x?≤?0.04. Remarkable negative magnetization is observed when x reaches to 0.06 and persists up to x?=?0.1. Two-sublattice model is established and competition of the two magnetic sublattices is responsible for the phenomenon. The magnetic switching effect is realized just by changing the magnitude of the applied magnetic field and double magnetocaloric effects are obtained. These unique features under low magnetic fields show attractive for application in spintronic devices due to that the magnetic state can effectively be tuned through magnetic field or temperature. Besides, the system exhibits both positive and negative exchange bias fields which are considered to be originating from the unidirectional anisotropy of exchange coupling of antiferromagnetic/ferromagnetic phases and spin reorientation of the two sublattices magnetic moments, respectively.     

Double hysteresis loops and enhanced mechanical quality factor of Mn-doped 0.75PMN-0.25PT ceramics

Relaxor ferroelectric 0.75 Pb(Mg_1/3Nb_2/3)O₃-0.25PbTiO₃ (0.75PMN-0.25PT) ceramics with Mn-doping concentration of 0%, 1%, 2% and 3 mol% were prepared by two-step sintering. The phase composition, microstructure, dielectric property, ferroelectric property, piezoelectric property and electromechanical property were investigated. Results indicate that all ceramics exhibit pure perovskite phases and high density. Mn-doping induces some decrease in dielectric constant ε_r, dielectric loss tanδ, remnant polarization P_r, piezoelectric coefficient d₃₃, and electromechanical coupling coefficient k_p, while significant increase in mechanical quality factor Q_m and the figure of merit (FOM) of 0.75PMN-0.25PT ceramics. For 3 mol% Mn-doped 0.75PMN-0.25PT ceramics, Q_m enhances by 1449%, FOM increases by 923%, and tanδ decreases by 67%, which makes it more suitable for high power applications. Interestingly, double P-E loops are observed in 3 mol% Mn-doped 0.75PMN-0.25PT ceramics. The phenomenon was investigated by the symmetry-conforming principle of point defects and the internal bias field.     

Reference databases,primer choice,and assay sensitivity for environmental metabarcoding: Lessons learnt from a re‐evaluation of an eDNA fish assessment in the Volga headwaters

Biodiversity monitoring via environmental DNA, particularly metabarcoding, is evolving into a powerful assessment tool for riverine systems. However, for metabarcoding to be fully integrated into standardized monitoring programmes, some current challenges concerning sampling design, laboratory workflow, and data analysis need to be overcome. Here, we review some of these major challenges and potential solutions. We further illustrate three potential pitfalls, namely the choice of suitable metabarcoding primers, the necessity of complete reference databases, and varying assay sensitivities, by a reappraisal of our‐own recently carried out metabarcoding study in the Volga headwaters. TaqMan qPCRs had detected catfish (Silurus glanis) and European eel (Anguilla anguilla), whereas metabarcoding had not, in the same samples. Furthermore, after extending the genetic reference database by 12 additional species and re‐analysing the metabarcoding data, we additionally detected the Siberian spiny loach (Cobitis sibirica) and Ukrainian brook lamprey (Eudontomyzon mariae) and reassigned the operational taxonomic units previously assigned to Misgurnus fossilis to Cobitis sibirica. In silico analysis of metabarcoding primer efficiencies revealed considerable variability among primer pairs and among target species, which could lead to strong primer bias and potential false‐negatives in metabarcoding studies if not properly compensated for. These results highlight some of the pitfalls of eDNA‐metabarcoding as a means of monitoring fish biodiversity in large rivers, which need to be considered in order to fully unleash the full potential of these approaches for freshwater biodiversity monitoring.