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排序方式: 共有1021条查询结果,搜索用时 15 毫秒
31.
David Peón Jorge Rodríguez-Álvarez Edelmiro López-Iglesias 《Papers in Regional Science》2019,98(6):2479-2502
The natural experiment provided by the opening of a section that completed the A8 motorway in Mariña de Lugo, a rural area in Galicia (Spain), offers an opportunity to identify whether spread or backwash effects in economic activity are observed. The new section directly affects only a small strip of the territory—where the transition from the inland rural areas to the more dynamic coastal area takes place. This allows us to test a separate dual inner-coastal socio-economic performance after the opening of the new road—an analysis that has rarely been performed for rural areas in developed countries. We study the impact over population growth, employment and business financial results, using the differences-in-differences approach. The results we obtain are consistent with the spread hypothesis for the nearest municipality to the new road section, while the spread effects did not disseminate to the neighbouring municipalities. These global results hide a different performance at the sector level, positive for transport and manufacturing companies, and negative for retail firms and hospitality. 相似文献
32.
The purpose of this study was to characterize and compare the carcass characteristics, cholesterol concentration, fatty acid composition of intramuscular fat and subcutaneous fat, and meat quality of Criollo Argentino and Braford steers reared in an extensive system, without supplementation, and slaughtered at approximately 400 kg live weight. The Braford steers had greater (P < 0.05) carcass weight, yield, conformation score, marbling degree, fat thickness and fatness score than Criollo Argentino steers. The tissue composition of the 10th rib was: 68.1% vs. 63.6% muscle, 23.9% vs. 20.4% bone and 8.2% vs. 16.3% fat for the Criollo Argentino and Braford breeds, respectively. The meat of Longissimus muscle from Braford steers was lighter, redder, yellower and more tender than that from Criollo Argentino steers. The meat of Longissimus muscle from Braford steers had a higher fat content, similar protein and ash contents and a lower (P ? 0.001) cholesterol concentration than that from Criollo Argentino steers. 相似文献
33.
Rostam Abdollahi-Arpanahi Gota Morota Francisco Peñagaricano 《Journal of dairy science》2017,100(12):9656-9666
The genomic prediction of unobserved genetic values or future phenotypes for complex traits has revolutionized agriculture and human medicine. Fertility traits are undoubtedly complex traits of great economic importance to the dairy industry. Although genomic prediction for improved cow fertility has received much attention, bull fertility largely has been ignored. The first aim of this study was to investigate the feasibility of genomic prediction of sire conception rate (SCR) in US Holstein dairy cattle. Standard genomic prediction often ignores any available information about functional features of the genome, although it is believed that such information can yield more accurate and more persistent predictions. Hence, the second objective was to incorporate prior biological information into predictive models and evaluate their performance. The analyses included the use of kernel-based models fitting either all single nucleotide polymorphisms (SNP; 55K) or only markers with presumed functional roles, such as SNP linked to Gene Ontology or Medical Subject Heading terms related to male fertility, or SNP significantly associated with SCR. Both single- and multikernel models were evaluated using linear and Gaussian kernels. Predictive ability was evaluated in 5-fold cross-validation. The entire set of SNP exhibited predictive correlations around 0.35. Neither Gene Ontology nor Medical Subject Heading gene sets achieved predictive abilities higher than their counterparts using random sets of SNP. Notably, kernel models fitting significant SNP achieved the best performance with increases in accuracy up to 5% compared with the standard whole-genome approach. Models fitting Gaussian kernels outperformed their counterparts fitting linear kernels irrespective of the set of SNP. Overall, our findings suggest that genomic prediction of bull fertility is feasible in dairy cattle. This provides potential for accurate genome-guided decisions, such as early culling of bull calves with low SCR predictions. In addition, exploiting nonlinear effects through the use of Gaussian kernels together with the incorporation of relevant markers seems to be a promising alternative to the standard approach. The inclusion of gene set results into prediction models deserves further research. 相似文献
34.
Due to the increase in the number and popularity of applications such as e-commerce or on-line booking systems, typical of the Web 2.0, dynamic contents are becoming more and more frequent. This trend suggests the review of widely accepted paradigms and models for the World Wide Web. As a system that is continuously changing, both in the offered applications and in its infrastructure, performance evaluation studies are a main concern to provide sound proposals when designing new web-related systems. Although the dynamism in the workload characterization has also been tackled in previous research, it has not been modeled in a precise way yet because of its complex nature.In this paper we propose the Dweb model which represents the dynamism of current web applications in the workload characterization. Dweb is based on three main concepts that allow to model dynamic workload: navigation, workload test and workload distribution. In addition, a dynamic workload generator has been implemented to show the practical application of the proposed model, which has been illustrated through a case study. 相似文献
35.
Miller Matthew J.; Sendrowitz Kerrin; Connacher Christopher; Blanco Susana; de la Pe?a Cristina Mu?iz; Bernardi Shaina; Morere Lauren 《Canadian Metallurgical Quarterly》2009,56(4):495
In this study, the authors examined the degree to which social-cognitive career theory (SCCT; R. W. Lent, S. D. Brown, & G. Hackett, 1994) explained the development of social justice interest and commitment. Data from 274 college students and latent variable path modeling were used to test theoretically and empirically derived SCCT direct and indirect effects structural models. The direct effects model estimated the direct effect of social supports and barriers on social justice commitment and the indirect effects model estimated the effect of social supports and barriers indirectly through self-efficacy. Overall, the present findings supported the use of SCCT within the social justice domain, as social justice self-efficacy and outcome expectations were useful in explaining the development of college students’ social justice interest and commitment. The present findings supported the indirect effects model of social justice interest and commitment over the direct effects model. Finally, unique to prior tests of SCCT in vocational and academic domains, social supports and barriers exhibited an indirect effect on commitment through outcome expectations. Study limitations, future directions for research, and implications for facilitating college students’ social justice interest and commitment are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
Alejandro Peña P Jesús A. Hernández Victoria M. Toro 《Environmental Modelling & Software》2010,25(12):1890-1893
This article presents a model based on the principles of evolutionary computation and on the principles of dispersion of an Inverse lagrangian puff model of the type Backward gaussian puff tracking in order to determine the spatial behavior over time of the concentration for PM2.5 and PM10 in a study area. 相似文献
37.
38.
Elena Fernández Ángel Alegría Susana Delgado Baltasar Mayo 《International Dairy Journal》2010,20(3):142-148
A series of Lactococcus garvieae strains isolated as the majority population of a Spanish traditional, starter-free cheese made from raw milk were phenotypically and genotypically characterised to address their biochemical potential, safety requirements, and technological properties. As expected, all L. garvieae cheese strains fermented lactose but grew slowly in UHT-treated milk. Enzymatic activities of L. garvieae were similar to those of Lactococcus lactis, although higher esterase and lipase activities were recorded for L. garvieae strains. Profiles of the volatile compounds produced from milk by L. garvieae and L. lactis strains were also comparable. L. garvieae strains did not produce haemolysin, gelatinase and the biogenic amines tyramine and histamine. Five L. garvieae stains showed tetracycline resistance encoded by a tet(M) gene. The use of L. garvieae strains as starter or adjunct cultures might be recommended for certain cheese types, provided that the safety of the strains has been demonstrated. 相似文献
39.
Daniele Zulim Botega Sara Bastida Susana Marmesat Lourdes Pérez-Olleros Baltasar Ruiz-Roso Francisco J. Sánchez-Muniz 《Journal of the American Oil Chemists' Society》2009,86(5):419-425
Heated oils may contain potentially toxic altered compounds. A denatured carob fiber, very rich in non-extractable tannins (Exxenterol®), exhibits antioxidant activities in in vitro experiments. The present study was designed to evaluate in sunflower oil (SO) heated to frying temperature, the protective effect on oil thermal oxidation and polymerization of adding 10 mg Exxenterol/kg oil (SO-10) and 50 mg Exxenterol/kg oil (SO-50). After 2, 8 and 16 h at 180 °C, SO displayed a relevant increase in triacylglycerol-derived polar material (PM) and polymer contents and a decrease in α-tocopherol concentrations. Thermal oxidation changes were significantly checked in SO-50 throughout the 16-h heating, while SO-10 only displayed protection from thermal oxidation during the first 2 h of heating. Oil frying-life was doubled because formation of PM and polymers was inhibited by more than 50%. Results clearly show that this non-extractable tannin-rich fiber can be successfully employed as an additive to significantly prolong sunflower oil frying-life, and thus decrease the potential toxicity of the heated oil. 相似文献
40.
Study of the aromatic by-products formed from ozonation of anilines in aqueous solution 总被引:6,自引:0,他引:6
Aqueous solutions of aniline and p-chloroaniline were treated with ozone in order to study the reaction and oxidation by-products. Aniline solutions were ozonated at low and high pH, so as to compare both molecular and hydroxyl free radical mechanisms, respectively. The main identified aromatic by-products were nitrobenzene and azobenzene when the experiment was carried out at acid pH. Formation of nitrobenzene, azobenzene, azoxybenzene and 2-pyridine-carboxylic was observed when the ozonation was carried out at basic pH. p-Chloroaniline was treated with ozone only at high pH and the identified by-products were in accordance with those obtained in the ozonation of aniline: p-chloronitrobenzene, 4,4'-dichloroazobenzene and 4-chloro-2-pyridine-carboxylic acid. All the aromatic by-products found were less toxic than the raw materials. The pseudo-first-order constants in aniline concentration were calculated, whilst kinetic in p-chloroaniline concentration could not be adjusted to a first-order reaction. 相似文献