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排序方式: 共有3093条查询结果,搜索用时 9 毫秒
1.
《Journal of dairy science》2022,105(3):2439-2452
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. 相似文献
2.
Hamid Azizi Bondarabady 《Journal of Urbanism》2018,11(2):202-232
According to many researchers and scholars, religious beliefs can be considered as the most influential factor in forming Muslim urban spaces and their architectural elements. In fact, historical cities reflect the culture and beliefs of their residences. Among all historical places in Iranian cities, the historical texture of the city of Yazd, especially the quarters since the age of Qajar dynasty, are well preserved. The present study aims at identifying the Islamic principles and values influencing the formation of architectural spaces and the extent of their applications in one of the historical quarters known as Golchinan. The results of the conformation of the theoretical findings with the data acquired from field studies revealed that almost 90% of the urban and architectural spaces (e.g. residential areas, mosques, bazaars, and pathways) in Yazd are directly influenced by Islamic principles. In other words, there is a strong conformity between the accepted Islamic values of the society and what actually was applied to urban constructions during Qajar dynasty. 相似文献
3.
William M. Pitts Martin Werrel Marco Fernandez Mary A. Long Evan A. Eisenberg James Filliben Cory D. Runyon 《火与材料》2021,45(1):127-154
Fire spread and growth on real‐scale four cushion mock‐ups of residential upholstered furniture (RUF) were investigated with the goal of identifying whether changes in five classes of materials (barrier, flexible polyurethane foam, polyester fiber wrap, upholstery fabric, and sewing thread), referred to as factors, resulted in statistically significant changes in burning behavior. A fractional factorial experimental design plus practical considerations yielded a test matrix with 20 material combinations. Experiments were repeated a minimum of two times. Measurements included fire spread rates derived from video recordings and heat release rates (HRRs). A total of 13 experimental parameters (3 based on the videos and 10 on the HRR results), referred to as responses, characterized the measurements. Statistical analyses based on Main Effects Plots (main effects) and Block Plots (main effects and factor interactions) were used. The results showed that three of the factors resulted in statistically significant effects on varying numbers of the 13 responses. The Barrier and Fabric factors had the strongest main effects with roughly comparable magnitudes. Foam was statistically significant for fewer of the responses and its overall strength was weaker than for Barrier and Fabric. No statistically significant main effects were identified for Wrap or Thread. Multiple two‐term interactions between factors were identified as being statistically significant. The Barrier*Fabric interaction resulted in the highest number of and strongest statistically significant effects. The existence of two‐term interactions means that it will be necessary to consider their effects in approaches designed to predict the burning behavior of RUF. 相似文献
4.
玉林胜果寺古代冶铸遗址位于广西玉林市兴业县龙安镇杨前村胜果寺附近的丘陵,面积超过2 000m~2。采用扫描电镜及能谱分析(SEM-EDS)、金相和矿相等研究方法,对胜果寺古代冶铸遗址的5个冶金遗物炉渣样品进行成分和显微组织分析检测。结果表明,该遗址为生铁冶铸遗址,炼渣属锰硅铝系高锰炉渣。冶炼产品除供本地铸锅等生产生活用品外,大量运往韶州涔水场浸铜。 相似文献
5.
Zixuan CHEN Tao LIU Xiao MA Hanyu TANG Jianyou HUANG Jianzhong PEI 《Frontiers of Structural and Civil Engineering》2022,16(7):896
Because of favorable mechanical properties, deformation resistance and being conducive to environmental protection, honeycomb fabricated plastic pavement slabs are highly recommended these years. At present, most studies focus on the performance of plastic materials, however, the dimension optimization of fabricated plastic pavement slab is rarely mentioned. In this paper, an optimized geometry of the honeycomb pavement slab was determined through finite element analysis. Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored. Several dimension factors were taken into consideration including the side length, rib thickness, the thickness of both top and bottom slabs of honeycomb structure and the length, the width and the thickness of the fabricated plastic slab. The results showed that honeycomb pavement slab with 6 cm bottom slab, 12 cm top slab,18 cm side length and 6 cm rib thickness is recommended, additionally, an external dimension of 4 m × 4 m × 0.45 m is suggested. Then, the mechanical responses of this optimized fabricated plastic slab were further investigated. Significance of different influencing factors, including wheel load, elastic modulus of plastic material, base layer thickness, soil foundation modulus and base layer modulus were ranked. 相似文献
6.
Rahman Saeed‐ur Shujaul Mulk Khan Mushtaq Ahmad Muhammad Zafar Raees Khan Muhammad Khalid Hui Nan Farooq Jan Sadaf‐Ilyas Kayani Sajad Hussain 《Microscopy research and technique》2020,83(5):541-550
Taxonomy of the genus Berberis is quite complex, due to overlapping morphological characters, making it very difficult to differentiate the species within the genus. In order to resolve this taxonomic complexity, the foliar anatomy of 10 Berberis L. species was carried out, for the first time from Pakistan, using light microscopy (LM). Significant variation in terms of epidermal cells shape, size, cell wall pattern, and stomata type was observed. B. baluchistanica has the largest epidermal cells, Adaxial: length = 45–(53.9 ± 3.6)–62.5 μm; and width = 22.5–(26.3 ± 1.3)–30 μm; Abaxial: length = 37.5–(43.25 ± 2.5)–50 μm; and width = 20–(22.6 ± 0.8)–25. The highest number of stomata was observed in B. glaucocarpa as 62 on the abaxial surface while the lowest number of stomata was recorded in B. baluchistanica as 8 on the adaxial surface. Of 10 investigated species, 6 possess anomocytic type stomata, while 2 species that is, B. aitchisonii and B. parkeriana have both anomocytic and anisocytic stomata while B. baluchistanica and B. calliobotrys have only paracytic type stomata. The highest number of cells per unit area was present on the adaxial surface of B. calliobotrys ranging from 245–(252.4)–260 followed by B. parkeriana with 209–(227.8)–250 on the abaxial surface. Stomatal index (SI) also varied considerably and was the lowest (2.6) percentage in B. baluchistanica and highest (31.9) percentage in B. kunawurensis. A taxonomic key based on micro‐morphological characters is provided for species identification. 相似文献
7.
Dirk Bühler 《Mauerwerk》2020,24(1):26-36
The Rank construction company and the introduction of brick vaults in Munich after 1945 The construction of vaults without scaffolding with thin bricks has a centuries‐old tradition, particularly in Spain and Italy. Since the beginning of the 19th century, it has been successfully spread mainly on the American double continent. The Rank Brothers construction company in Munich is known to date as one of those construction companies that began building with concrete in its home city very early on. New investigations, which were made possible above all by the provision of archive material by Paul Basiner, now point to an additional focus of this company's work. The architects and engineers of the company had been also able to familiarise themselves with this traditional Spanish brick‐vaulted construction method via the branch office in Spain, which was established from 1911 on. This knowledge was particularly in demand in the years following World War II, when the destroyed vaults had to be rebuilt with simple means and low material consumption. Together with Carl Sattler, who had become acquainted with similar construction methods in Italy, brick vaults were initially used to complete the construction of the Landeszentralbank in Munich. In the following years, Rank was able to provide many buildings in and around Munich with brick vaults. It was not until the 1960s that this construction technique went out of fashion and was thus somewhat forgotten. 相似文献
8.
山西省太原市西南的蒙山南麓风峪沟沿线遍布众多石碹窑洞,形成了具有明显地域性特点的传统建筑群。通过对其中周家庄古村的调查研究,将古村内石碹窑洞群中具有代表性的周家粮铺院作为研究对象,以此院落的建筑布局、内部空间营造及建造技术特点为主要内容,对该地区建筑遗存信息和文献资料进行整理研究,对建筑群体进行实地勘查及计算机建模,为山西传统村落的保护和可持续发展提供合理依据。 相似文献
9.