Academic literature on the topic 'Mating a-factor'
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Journal articles on the topic "Mating a-factor"
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Hirschhorn, J. N., and F. Winston. "SPT3 is required for normal levels of a-factor and alpha-factor expression in Saccharomyces cerevisiae." Molecular and Cellular Biology 8, no. 2 (February 1988): 822–27. http://dx.doi.org/10.1128/mcb.8.2.822-827.1988.
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Mutations in the Saccharomyces cerevisiae SPT3 gene were previously found to cause suppression of Ty and delta insertion mutations in 5'-noncoding regions of genes. This suppression likely results from the fact that SPT3 is required for transcription initiation in delta sequences. Other additional phenotypes of spt3 mutants, including a mating defect, suggest that SPT3 is required for normal levels of expression of other genes. We analyzed the mating defect in spt3 mutants and showed that the levels of transcripts of the three major mating pheromone genes, MF alpha 1, MFa1, MFa2, were all reduced. The reduction in expression of these genes in spt3 mutants was not due to expression of a silent mating type cassette. Furthermore, we showed that the spt3 mating defect was manifest at the levels of both cellular fusion and nuclear fusion.
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Hirschhorn, J. N., and F. Winston. "SPT3 is required for normal levels of a-factor and alpha-factor expression in Saccharomyces cerevisiae." Molecular and Cellular Biology 8, no. 2 (February 1988): 822–27. http://dx.doi.org/10.1128/mcb.8.2.822.
Full textAbstract:
Mutations in the Saccharomyces cerevisiae SPT3 gene were previously found to cause suppression of Ty and delta insertion mutations in 5'-noncoding regions of genes. This suppression likely results from the fact that SPT3 is required for transcription initiation in delta sequences. Other additional phenotypes of spt3 mutants, including a mating defect, suggest that SPT3 is required for normal levels of expression of other genes. We analyzed the mating defect in spt3 mutants and showed that the levels of transcripts of the three major mating pheromone genes, MF alpha 1, MFa1, MFa2, were all reduced. The reduction in expression of these genes in spt3 mutants was not due to expression of a silent mating type cassette. Furthermore, we showed that the spt3 mating defect was manifest at the levels of both cellular fusion and nuclear fusion.
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Michaelis, S., and I. Herskowitz. "The a-factor pheromone of Saccharomyces cerevisiae is essential for mating." Molecular and Cellular Biology 8, no. 3 (March 1988): 1309–18. http://dx.doi.org/10.1128/mcb.8.3.1309-1318.1988.
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The Saccharomyces cerevisiae pheromone a-factor is produced by a cells and interacts with alpha cells to cause cell cycle arrest and other physiological responses associated with mating. Two a-factor structural genes, MFA1 and MFA2, have been previously cloned with synthetic probes based on the a-factor amino acid sequence (A. Brake, C. Brenner, R. Najarian, P. Laybourn, and J. Merryweather, cited in M.-J. Gething [ed.], Protein transport and secretion, 1985). We have examined the function of these genes in a-factor production and mating by construction and analysis of chromosomal null mutations. mfa1 and mfa2 single mutants each exhibited approximately half the wild-type level of a-factor activity and were proficient in mating, whereas the mfa1 mfa2 double mutant produced no a-factor and was unable to mate. These results demonstrate that both genes are functional, that each gene makes an equivalent contribution to the a-factor activity and mating capacity of a cells, and that a-factor plays an essential role in mating. Strikingly, exogenous a-factor did not alleviate the mating defect of the double mutant, suggesting that an a cell must be producing a-factor to be an effective mating partner.
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Michaelis, S., and I. Herskowitz. "The a-factor pheromone of Saccharomyces cerevisiae is essential for mating." Molecular and Cellular Biology 8, no. 3 (March 1988): 1309–18. http://dx.doi.org/10.1128/mcb.8.3.1309.
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The Saccharomyces cerevisiae pheromone a-factor is produced by a cells and interacts with alpha cells to cause cell cycle arrest and other physiological responses associated with mating. Two a-factor structural genes, MFA1 and MFA2, have been previously cloned with synthetic probes based on the a-factor amino acid sequence (A. Brake, C. Brenner, R. Najarian, P. Laybourn, and J. Merryweather, cited in M.-J. Gething [ed.], Protein transport and secretion, 1985). We have examined the function of these genes in a-factor production and mating by construction and analysis of chromosomal null mutations. mfa1 and mfa2 single mutants each exhibited approximately half the wild-type level of a-factor activity and were proficient in mating, whereas the mfa1 mfa2 double mutant produced no a-factor and was unable to mate. These results demonstrate that both genes are functional, that each gene makes an equivalent contribution to the a-factor activity and mating capacity of a cells, and that a-factor plays an essential role in mating. Strikingly, exogenous a-factor did not alleviate the mating defect of the double mutant, suggesting that an a cell must be producing a-factor to be an effective mating partner.
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Brizzio, V., A. E. Gammie, G. Nijbroek, S. Michaelis, and M. D. Rose. "Cell fusion during yeast mating requires high levels of a-factor mating pheromone." Journal of Cell Biology 135, no. 6 (December 15, 1996): 1727–39. http://dx.doi.org/10.1083/jcb.135.6.1727.
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During conjugation, two yeast cells fuse to form a single zygote. Cell fusion requires extensive remodeling of the cell wall, both to form a seal between the two cells and to remove the intervening material. The two plasma membranes then fuse to produce a continuous cytoplasm. We report the characterization of two cell fusion defective (Fus-) mutants, fus5 and fus8, isolated previously in our laboratory. Fluorescence and electron microscopy demonstrated that the fus5 and fus8 mutant zygotes were defective for cell wall remodeling/removal but not plasma membrane fusion. Strikingly, fus5 and fus8 were a specific; both mutations caused the mutant phenotype when present in the MATa parent but not in the MAT alpha parent. Consistent with an a-specific defect, the fus5 and fus8 mutants produced less a-factor than the isogenic wild-type strain. FUS5 and FUS8 were determined to be allelic to AXL1 and RAM1, respectively, two genes known to be required for biogenesis of a-factor. Several experiments demonstrated that the partial defect in a-factor production resulted in the Fus- phenotype. First, overexpression of a-factor in the fus mutants suppressed the Fus- defect. Second, matings to an MAT alpha partner supersensitive to mating pheromone (sst2 delta) suppressed the Fus- defect in trans. Finally, the gene encoding a-factor, MFA1, was placed under the control of a repressible promoter; reduced levels of wild-type a-factor caused an identical cell fusion defect during mating. We conclude that high levels of pheromone are required as one component of the signal for prezygotes to initiate cell fusion.
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Tanaka, Ayako, Kazuhiro Miyazaki, Haruki Murakami, and Susumu Shiraishi. "Sequence characterized amplified region markers tightly linked to the mating factors ofLentinula edodes." Genome 47, no. 1 (January 1, 2004): 156–62. http://dx.doi.org/10.1139/g03-131.
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Detecting the mating types in shiitake, Lentinula edodes (Berk.) Pegler, is important for making progress in the breeding of this mushroom and determining the compatibility of the pair to cross. Shiitake is a tetrapolar fungus with two unlinking mating factors, A factor and B factor. We screened molecular markers linked to the mating factors using the randomly amplified polymorphic DNA (RAPD) method to develop the mating type identification procedure. Using 147 oligonucleotide primers, a total of 6 linkage markers for the shiitake mating factors, 4 markers for the A factor and 2 markers for the B factor, were discovered with a logarithm of the odds threshold of 3.0 for linkage. Two RAPDs that perfectly segregated with each mating factor among 72 basidiospore strains were detected. Both of these RAPDs were cloned and sequenced to convert them to the sequence characterized amplified region (SCAR) markers. Four primers, two sets of primers, were designed according to the internal sequences of two RAPDs tightly linking to the A factor or B factor. Consequently, we determined the polymerase chain reaction condition for multiplex analyses of these SCAR markers.Key words: Lentinula edodes, SCAR, diagnostic, mating type.
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Davey, J. "M-factor, a farnesylated mating factor from the fission yeast Schizosaccharomyces pombe." Biochemical Society Transactions 24, no. 3 (August 1, 1996): 718–23. http://dx.doi.org/10.1042/bst0240718.
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Chen, Peng, Stephanie K. Sapperstein, Jonathan D. Choi, and Susan Michaelis. "Biogenesis of the Saccharomyces cerevisiae Mating Pheromone a-Factor." Journal of Cell Biology 136, no. 2 (January 27, 1997): 251–69. http://dx.doi.org/10.1083/jcb.136.2.251.
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The Saccharomyces cerevisiae mating pheromone a-factor is a prenylated and carboxyl methylated extracellular peptide signaling molecule. Biogenesis of the a-factor precursor proceeds via a distinctive multistep pathway that involves COOH-terminal modification, NH2-terminal proteolysis, and a nonclassical export mechanism. In this study, we examine the formation and fate of a-factor biosynthetic intermediates to more precisely define the events that occur during a-factor biogenesis. We have identified four distinct a-factor biosynthetic intermediates (P0, P1, P2, and M) by metabolic labeling, immunoprecipitation, and SDSPAGE. We determined the biochemical composition of each by defining their NH2-terminal amino acid and COOH-terminal modification status. Unexpectedly, we discovered that not one, but two NH2-terminal cleavage steps occur during the biogenesis of a-factor. In addition, we have shown that COOH-terminal prenylation is required for the NH2-terminal processing of a-factor and that all the prenylated a-factor intermediates (P1, P2, and M) are membrane bound, suggesting that many steps of a-factor biogenesis occur in association with membranes. We also observed that although the biogenesis of a-factor is a rapid process, it is inherently inefficient, perhaps reflecting the potential for regulation. Previous studies have identified gene products that participate in the COOH-terminal modification (Ram1p, Ram2p, Ste14p), NH2-terminal processing (Ste24p, Axl1p), and export (Ste6p) of a-factor. The intermediates defined in the present study are discussed in the context of these biogenesis components to formulate an overall model for the pathway of a-factor biogenesis.
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Hughes, D. A., N. Yabana, and M. Yamamoto. "Transcriptional regulation of a Ras nucleotide-exchange factor gene by extracellular signals in fission yeast." Journal of Cell Science 107, no. 12 (December 1, 1994): 3635–42. http://dx.doi.org/10.1242/jcs.107.12.3635.
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The ste6 gene of Schizosaccharomyces pombe encodes a putative GDP-GTP exchange factor for the ras1 gene product. Genetic analysis of the ste6 and ras1 genes has shown that they are required for mating and for the response to mating pheromones. In this study we show that expression of the ste6-encoded mRNA is induced by nitrogen starvation, the physiological signal that triggers mating and sexual differentiation. Exposure to mating pheromones enhances the induction of ste6 expression upon nitrogen starvation. Pheromone-induced expression requires not only the function of components of the pheromone-signalling pathway, but also ras1 function. Furthermore, mutants in which the Ras1 protein is activated have higher basal and induced levels of ste6 gene expression than wild-type cells. These observations indicate the existence of a positive-feedback loop through which Ras1 stimulates the expression of its own activator. Since Ste6 is likely to promote the exchange of guanine nucleotides on Ras1 protein, our results suggest an important role for GDP-GTP exchange in the regulation of Ras1 activity during the mating process in S. pombe.
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Xue, Chu-Biao, Guy A. Caldwell, Jeffrey M. Becker, and Fred Naider. "Total synthesis of the lipopeptide a-mating factor ofSaccharomyces cerevisiae." Biochemical and Biophysical Research Communications 162, no. 1 (July 1989): 253–57. http://dx.doi.org/10.1016/0006-291x(89)91989-x.
Full textDissertations / Theses on the topic "Mating a-factor"
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Nooker, Jacqueline Kay. "Factors affecting the demography of a lek-mating bird: the greater prairie-chicken." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/375.
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Chang, Chien-I. "Functional Analysis of Yeast Pheromone Receptors in ER Exit, Ligand-Induced Endocytosis and Oligomerization: A Dissertation." eScholarship@UMMS, 2009. https://escholarship.umassmed.edu/gsbs_diss/418.
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This study investigates endocytosis and ER export signals of the yeast α-factor receptor and the role that receptor oligomerization plays in these processes. The α-factor receptor contains signal sequences in the cytoplasmic C-terminal domain that are essential for ligand-mediated endocytosis. In an endocytosis complementation assay, I found that oligomeric complexes of the receptor undergo ligand-mediated endocytosis when the α-factor binding site and the endocytosis signal sequences are located in different receptors. Both in vitro and in vivo assays strongly suggested that ligand-induced conformational changes in one Ste2 subunit do not affect neighboring subunits. Therefore, the recognition of endocytosis signal sequence and the recognition of the ligand-induced conformational change are likely to be two independent events, where the signal sequence plays only a passive role in the ligand-induced endocytosis. Four amino acid substitutions (C59R, H94P, S141P and S145P) in TM domains I, II and III were identified that resulted in the accumulation of truncated receptors in the ER but did not block ER export of full-length receptors. The two DXE motifs in the C-terminal tail were required for export of the mutant receptors from the ER; however DXE was not essential for proper cell surface expression of wild-type receptors apparently because the receptors contain redundant ER export signals. An assay for oligomerization of receptors in the ER was developed based on the ability of truncated mutant receptors to exit the ER. The four substitutions (C59R, H94P, S141P and S145P) that caused DXE-dependent ER export failed to form homo-oligomers, suggesting that the DXE motifs and receptor oligomerization serve as independent ER export signals. Consistent with this view, two of the substitutions (S141P and S145P), when coexpressed, with wild-type receptors, formed hetero-oligomers that exited the ER. Finally, the full-length oligomer-defective mutant Ste2-S141P was sensitive to α-factor, suggesting that receptor monomers that reach the cell surface are able to activate the heterotrimeric G protein. The potential roles that TM1, 2 and 3 play in receptor oligomerization are discussed.
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Cabeza, De Baca Tomás. "A Journey through Time and Space: Examining the Influence of Contextual Factors on the Ontogeny of Human Life History Strategies." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/315867.
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Researchers must consider the role of context when examining the behavior and characteristics of an individual. An individual must alter development, characteristics, and behavior, to adequately meet the challenges presented within their ecology. The following dissertation presents three manuscripts that examine individual differences while considering the role ecological (spatial) and developmental (temporal) context plays on the individual. Each paper utilizes Life History Theory to examine and to integrate the study findings into a cohesive framework. Life history theory is an evolutionary-developmental theory that focuses on how allocation of bioenergetic and material resources to different developmental facets will have long-term implications for behavior, traits, and health. Each paper collectively highlights key contextual factors throughout the lifespan and seeks to understand how life history strategies emerge. Study I examined the role mother's behavior had on the development of the child unpredictability schema (i.e., worldview where children view their environment and others as unreliable). The study included 65 children and their mothers. Results revealed that child unpredictability schema was predicted by mother's mating and parental effort. A quadratic effect was also found, whereby child unpredictability schema became constant at lower levels of parental effort. Study II utilized retrospective reports of childhood parental effort from extended kin family, positive emotional environment, and traditional social values from a sample of 200 Mexican and Costa Rican college students. High levels of childcare assistance from patrilineal and matrilineal kin were associated with more positive family environment, and the association was partially mediated between kin care and slow life history. Positive associations were also found between matrilineal kin childcare and traditional Latin social values. Study III utilized a nationally-representative, all-female sample to test whether higher reproductive effort increases physical/mental deterioration in women. Results reveal that reproductive effort and illness were mediated by both antioxidant defenses and inflammation. The results of the three studies broadly support hypotheses generated from Life History Theory. Contextual factors during key developmental stages have an impact on how an individual will allocate time and bioenergetic resources - thus contributing to specific behavioral life history strategies.
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Peter, Josephine Jasmine. "Identification of yeast genes enabling efficient oenological fermentation under nitrogen-limited conditions." Thesis, 2018. http://hdl.handle.net/2440/113360.
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Nitrogen deficiency can often lead to slow or sluggish fermentation, resulting in wine out of specification and at risk of oxidation and microbial contamination. Problems due to nitrogen deficiency can be rectified by optimising grape chemistry (through vineyard fertilization), or more commonly supplementing the fermentation with ammonium salts. An alternative is to use wine yeast that can utilize nitrogen efficiently and complete fermentation more reliably. However, to develop ‘nitrogen efficient’ yeast, it is important to understand how such yeast can utilize nitrogen effectively by identifying genes that influence fermentation performance over a range of nitrogen concentrations. Past research related to the identification of genes influencing nitrogen efficiency under fermentative conditions is largely confined to laboratory yeast. Investigation of the ~5,000 non-essential genes in yeast is possible through research tools such as deletion libraries (collections of strains, each with a single gene deletion). Several genomewide studies have successfully used deletion libraries in the auxotrophic background of laboratory yeast to investigate phenotypes in response to exposure to single stress factors associated with fermentation. However, the need to supplement with amino acids to overcome auxotrophies makes quantitative physiological studies in nitrogen limiting conditions impractical. Therefore, in this study, we have used a prototrophic deletion collection in both laboratory and wine yeast backgrounds to identify genes influencing fermentation performance. Screening (micro-fermentation; 600 μL) of the prototrophic laboratory yeast deletion library (BY4741; 5,372 deletants) and the partial wine yeast library (AWRI1631; 1,844 deletants) for growth and consumption of sugar and nitrogen under limiting (75 mg FAN L⁻¹) and non-limiting nitrogen (450 mg FAN L⁻¹) conditions identified deletants with improved fermentation. To better understand the role of individual genes in fermentation, candidate gene sets from each screen were compared to each other and to other published data sets from genome wide transcriptomic analyses related to fermentation. Wine yeast deletants that enabled shortened micro-fermentation duration in low nitrogen conditions were further investigated, since the experiment best represented nitrogen deficient grape must associated with problematic fermentation. Fifteen deletants completed fermentation quicker than the wildtype (c.a. a 15-59% time reduction) when tested in larger (100 mL) fermentations. This group of genes were annotated to biological processes including protein modification, transport, metabolism and ubiquitination (UBC13, MMS2, UBP7, UBI4, BRO1, TPK2, EAR1, MRP17, MFA2 and MVB12), signalling (MFA2) and amino acid metabolism (AAT2). Among the genes identified, MFA2 (mating a-factor), which conferred a 34% decrease in fermentation duration, was further investigated. We were interested to understand how deletion of this mating type gene affected fermentation since a link between these metabolic pathways would be novel. The 15 strains identified in this study, which were fermentation proficient in a ‘wine-like', limited nitrogen condition, provide a basis to better understand how yeast adapt to nitrogen limitation during fermentation. Furthermore, the corresponding genes can be targeted in second generation strain improvement programs, using tools such as CRISPR (yet to be approved by relevant regulatory bodies) to generate nitrogen efficient yeast to reduce the need to supplement low nitrogen fermentations.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Agriculture, Food and Wine, 2018.
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Chen, Chun-Hao, and 陳俊豪. "A Study of the Key Factors for Successful Matching between Employers and Foreign Care Workers in Elderly Family: From the Perspective of Two-Factor Theory." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/cagxac.
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碩士實踐大學
家庭研究與兒童發展學系高齡家庭服務事業碩士在職專班
106
The population structure has become increasingly ageing in Taiwan. If the degree of aging does not diminish, the elderly population ratio in 2025 will exceed 20% and it will become the “Super Aged Society”. According to estimates and investigations conducted by the Ministry of Health and Welfare and the Taiwan Association of Family Caregives from 2016 to 2017, there are approximately 760,000 to 780,000 persons with disabilities and long-term needs in Taiwan, of which 55% are taken care of by their families; 30% rely on foreign care workers, about 230,000 people. In addition, at the end of 2016, the survey of foreign workers in industry and social welfare shows that foreign home care workers have a total of 212,023 people regardless of nationality in Taiwan, among them, the largest number is Indonesian (173,803). However, according to statistics from the Ministry of Health and Welfare, as of the end of 2016, a total of 118,000 people completed the Level C technician for caring service training, and only 30,000 were actually employed. Foreign home care workers in Taiwan clearly have become the main force for the elderly to take care of the manpower market. This study is a descriptive study, and base on Herzberg's Two-Factor Theory, 420 valid questionnaires were collected from employers and foreign care workers in elderly family. The AHP hierarchy analysis method was used to find out the differences in the weight and cognition of motivation factors and hygiene factors between the two parties. Finally, it is hoped that the results of this study will provide academics and the public with regard to the awareness, feelings and ideas of foreign care workers. As well as providing cross-border human resource management operations and employers for elderly family, it is used as a reference and application when managing labor relations or when government agencies review relevant policies.
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Chang, Chia Hui, and 張嘉惠. "A Study on the Success Factors of Executive Search Firm Matching Executives." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/n6qms5.
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碩士國立中正大學
勞工關係學系暨研究所
102
Abstract The close cross-straits exchange of Taiwanese talent market and the wave of Asia-pacific markets to the talents in Taiwan have led to the fault of Taiwan’s top executive and the gap of human resource. Companies don’t depend on connections to find top executive talents but on the executive search of executive search firm. Although Taiwanese companies have been very familiar with such channel of executive search, it has retreated many companies to recruit through the channel for its high agency fee and efficiency. The study aims to discuss the success factors of executive search company matching executives. Through literature analysis and individual case in-depth interview method, the study conducted interviews among the three parties, namely, the executive search firm, employer's human resources department and executives of individual cases that are successfully matched, discussing the factors of executive search firm’s successful matching. Based on the Agency Theory and the Transaction Cost Theory, the relationship between executive search firm and employer was explained to define their relation structure and problems. It is found through the Agency Theory that inducement and supervision can assist executive search company to achieve the purpose of finding the suitable executives, while the employer shall adopt results-oriented service contract. However, from the perspective of Transaction Costs Theory, the executive search firm should cooperate with companies and executives with good faith by a certain mechanism， while the employer company should establish good management and examination system to cooperate with executive search firm. Both parties should stipulate complete cooperation contract to establish an interpersonal relationship with mutual trust and benignancy, lowering uncertainties and reducing transaction costs. From the individual case interview, the successful factors of executive firm matching executives are concluded as follows: (1) Good communication skills of employer’s HR. (2) Executive search specialists’ acquaintance with the industrial chain and good knowledge of employers’ demands learned from the human resource department. (3) Executive search specialists’ establishment of talents resource channels and good interpersonal connections. (4) Executive search specialists’ good communication skills. (5) Executive search specialists’ uphold of the principle of profession and integrity. Key words: executive search; executive search firm
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Chen, Ming-Ru, and 陳明汝. "The Relationship between Coagulation Factors and Carotid Stenosis: A Comparative Study of Different Propensity Score Matching Strategies." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/82653s.
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碩士中山醫學大學
公共衛生學系碩士班
102
Background: Several cohort and case-control studies have found that the coagulation factors were significantly associated with carotid stenosis. Therefore, with a nested case-control design, we conducted propensity scores (PS) matching to assess the relations of coagulation factors to carotid stenosis. Objectives: To determine the relationship between coagulation factors and carotid stenosis by using different PS matching strategies, and to explore the possible role of coagulation factors in atherosclerosis in the stratified analysis. Methods: Baseline data (1991-1993 & 1993-1997) and intima-media thickness values of the common carotid artery (1993-1997), from the survey of Cardiovascular Disease Risk Factors Two-Township Study in Taiwan were used. We choose the best strategy from 24 strategies composed of 2 sample selection schemes and 12 matching ways. Furthermore, the strategy was stratified by gender, region, cardiovascular disease status and PS after matching on the PS in a range of 0.05. Results: Increasing 1 SD of fibrinogen in 1991 or prothrombin time in 1993 was significantly associated with the incidence of carotid stenosis, odds ratios 1.27 (95% CI: 1.05, 1.53) and 1.29 (95% CI: 1.07, 1.55) respectively. This finding has also been seen in PS-stratified analyses, when PS of 1991, PS of 1993 or PS of 1991 and 1993 were in the stratified medium. Conclusions: The fibrinogen and the prothrombin time were significantly associated with carotid stenosis. This connection may exist before incident carotid artery disease. In particular, fibrinogen may not only be an inflammatory marker, but possibly also one of several causes of carotid stenosis.
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成培達. "A Study of the Factors Influencing a Firm''s Matching Strategy in Response to the Competitor''s New Product Preannouncement." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/70716077745810808120.
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Mellet, Juanita. "Factors determining the composition of a public cord blood stem cell bank including HLA diversity." Diss., 2013. http://hdl.handle.net/2263/33338.
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The human leukocyte antigen (HLA) is the most polymorphic region in the human genome and accounts for more than 10% of human diversity. This region plays an important role in matching donors and recipients for transplantation. The South African Bone Marrow Registry (SABMR) does not reflect the demographics of the South African population. The large number of polymorphisms resulting from HLA diversity in the Black South African population and their limited representation in the SABMR reduce the chances of finding adequate matches between donors and recipients in this group. Umbilical cord blood is an alternative to bone marrow for the treatment of fatal diseases. Less strict HLA matching is required due to the naive nature of the T cells in cord blood. A public umbilical cord blood bank is a necessity in trying to cater for the diverse population in South Africa. However, the ethnic diversity of the South African population poses a great challenge in constituting a public umbilical cord blood bank that is representative of the entire population. The Roche designed next generation sequencing (NGS) high resolution (HR) HLA typing kit enables sequencing of additional HLA exons and could improve the degree of matching between individuals to ultimately decrease adverse reactions. An extensive study of the literature was performed to establish the demographics, linguistics, and HLA diversity of the South African population to determine how a public cord blood bank should be constituted. In addition, HLA genotyping was performed by 454 NGS on 20 samples that had previously been HLA typed by conventional methods. The 454 NGS technique made use of a Roche designed medium and high resolution HLA typing kit to genotype the samples. It was possible to assign accurate genotypes to 95.5% of the loci of interest for the total number of 20 samples using the MR kit, compared with 98.5% using the HR kit. In conclusion, the present study indicates the extreme HLA diversity in the South African population, and therefore, recommends constituting the first public umbilical cord blood bank in Gauteng on the basis of race or major ethnic groupings. A minimum number of 10 000 cord blood units is needed to initiate the bank. Furthermore, the 454 NGS platform together with the HR HLA typing kit display potential as an alternative method to be used in a public cord blood bank, as well as routine clinical and diagnostic laboratories, to ultimately improve HLA matching between donors and recipients.Dissertation (MSc)--University of Pretoria, 2013.
gm2014
Immunology
unrestricted
Books on the topic "Mating a-factor"
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Alent'eva, Tat'yana. Public opinion in the United States on the eve of the Civil war (1850-1861), was. ru: INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1068789.
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The monograph first examines American public opinion as a major factor of social and political life in the period of the maturing of the Civil war (1861-1865 gg.). Special value it is given by the study of the struggle in the South and in the North, consideration of the process of formation of two socio-cultural models.
On the wide canvas of the socio-economic and political history in the monograph analyses the state and development of public opinion in the United States, sequentially from the compromise of 1850, a small civil war in Kansas, the uprising of John brown, of the maturing of "inevitable conflict," the secession of the southern States to the formation of the southern Confederacy and the Civil war. Reveals a fierce struggle, which was accompanied by the adoption of the compromise Kansas-Nebraska and the Supreme court decision in the Dred Scott case of 1857, which annulled the action of the famous Missouri compromise. Special attention is paid to the formation of the Republican party and the presidential elections of 1856 and 1860
Shown, as were incitement to hatred between citizens of the same country, which were used propaganda and manipulative techniques. The totality of facts gleaned from primary sources, especially the materials about these manipulations give an opportunity to look behind the scenes politics that led to the outbreak of the Civil war in the United States, a deeper understanding of its causes.
For students of historical faculties and departments of sociology and political Sciences, and anyone interested in American history.
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Dillon, Haley M., Lora E. Adair, and Gary L. Brase. Operational Sex Ratio and Female Competition. Edited by Maryanne L. Fisher. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780199376377.013.1.
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When there is a surplus of one sex in a population, members of that sex often compete against each other for access to the scarcer sex. This chapter reviews the theoretical foundations for this phenomenon, focusing on the concept of operational sex ratio (OSR; the ratio of viable and available males to females in a given mating market) versus overall sex ratio, as well as the phylogenetic evidence of sex ratios as an important factor influencing mating behaviors. Research on human OSR and its effects is a fairly recent development but has already led to findings that are generally coherent and consistent with the nonhuman evidence. The evidence to date indicates that people who find themselves in female-disadvantaged mating markets show systematic and adaptive changes in their behaviors, including increased female intrasexual competition. The chapter concludes with discussions of additional issues and future directions for research on OSR.
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Bindemann, Markus, ed. Forensic Face Matching. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198837749.001.0001.
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Person identification at passport control, at borders, in police investigations, and in criminal trials relies critically on the identity verification of people via image-to-image or person-to-image comparison. While this task is known as ‘facial image comparison’ in forensic settings, it has been studied as ‘unfamiliar face matching’ in cognitive science. This book brings together expertise from practitioners, and academics in psychology and law, to draw together what is currently known about these tasks. It explains the problem of identity impostors and how within-person variability and between-person similarity, due to factors such as image quality, lighting direction, and view, affect identification. A framework to develop a cognitive theory of face matching is offered. The face-matching abilities of untrained lay observers, facial reviewers, facial examiners, and super-recognizers are analysed and contrasted. Individual differences between observers, learning and training for face recognition and face matching, and personnel selection are reviewed. The admissibility criteria of evidence from face matching in legal settings are considered, focusing on aspects such as the requirement of relevance, the prohibition on evidence of opinion, and reliability. Key concepts relevant to automatic face recognition algorithms at airports and in police investigations are explained, such as deep convolutional neural networks, biometrics, and human–computer interaction. Finally, new security threats in the form of hyper-realistic mask disguises are considered, including the impact these have on person identification in applied and laboratory settings.
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Blanckenhorn, Wolf U. Behavioral, plastic, and evolutionary responses to a changing world. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797500.003.0019.
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Organisms can respond to environmental change by modifying their behavior to obtain an instant response, through short-term phenotypically plastic, often physiological, adjustments, and/or by adapting their life history through a more long-term evolutionary response. Behavioural and physiological responses, in fact, can occur at all these three temporal scales. Examples of behaviors so affected include congregation, dispersal, foraging, migration, or mating. Such responses have consequences at the population and community levels, and ultimately for the evolution of species. This chapter discusses insect examples of these kinds, with an emphasis on human-induced factors, such as (primarily) climate change, pollution, fragmentation, and urbanization.
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MacEacheron, Melanie, and Lorne Campbell. Moderation of Female–Female Competition for Matings by Competitors’ Age and Parity. Edited by Maryanne L. Fisher. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199376377.013.27.
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Previous research on female intrasexual competition, especially but not only for matings or mateships, has largely been conducted using convenience samples of women of undergraduate status and therefore generally between the ages of 17 and 22. Even among such articles including women over 25, the majority do not focus on mate competition. There is a priori reason, however, to believe that intrasexual competition for matings and mateships would extend and change beyond this life stage. This chapter provides an overview of the literature on female intrasexual competition over women’s reproductive careers, discusses factors that should result in predictable changes in female intrasexual competition as women age, and proposes testable hypotheses that should help guide future research in this area of research. Based on this analysis, new theories concerning reproductive advantage derivable from acquiring the status of successful mother are proposed.
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Hartl, Daniel L. A Primer of Population Genetics and Genomics. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198862291.001.0001.
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A Primer of Population Genetics and Genomics, 4th edition, has been completely revised and updated to provide a concise but comprehensive introduction to the basic concepts of population genetics and genomics. Recent textbooks have tended to focus on such specialized topics as the coalescent, molecular evolution, human population genetics, or genomics. This primer bucks that trend by encouraging a broader familiarity with, and understanding of, population genetics and genomics as a whole. The overview ranges from mating systems through the causes of evolution, molecular population genetics, and the genomics of complex traits. Interwoven are discussions of ancient DNA, gene drive, landscape genetics, identifying risk factors for complex diseases, the genomics of adaptation and speciation, and other active areas of research. The principles are illuminated by numerous examples from a wide variety of animals, plants, microbes, and human populations. The approach also emphasizes learning by doing, which in this case means solving numerical or conceptual problems. The rationale behind this is that the use of concepts in problem-solving lead to deeper understanding and longer knowledge retention. This accessible, introductory textbook is aimed principally at students of various levels and abilities (from senior undergraduate to postgraduate) as well as practising scientists in the fields of population genetics, ecology, evolutionary biology, computational biology, bioinformatics, biostatistics, physics, and mathematics.
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Kinuthia, Bethuel Kinyanjui. Agricultural input subsidy and farmers outcomes in Tanzania. UNU-WIDER, 2020. http://dx.doi.org/10.35188/unu-wider/2020/906-8.
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This paper examines the impact of the government input subsidy—the National Agriculture Input Voucher—on farmers’ production and welfare in Tanzania as well as the factors that influence agricultural production in the country. The analysis is based on the Living Standards Measurement Study-Integrated Surveys on Agriculture for 2008–13. The study uses panel fixed effects and difference-in-difference and propensity score matching methods to examine the two objectives. The results show that the input subsidy programme resulted in an initial increase in maize and rice production but not in the long run and only in a few regions. In addition, there was a decrease in total production in the southern region and the programme had little effect on farmers’ welfare. The results show that this programme only partly met the expected outcomes in Tanzania due to mistargeting, inaccurate identification of households, and poor implementation.
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Cleary, Paul, Sam Ghebrehewet, and David Baxter. Essential statistics and epidemiology. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198745471.003.0022.
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This chapter provides a grounding in basic statistics, descriptive epidemiology, analytical epidemiology, and hypothesis testing appropriate for health protection practitioners. The analysis of categorical data using frequency distributions, and charts, and the interpretation of epidemic curves is described. The description of quantitative data including central tendency, standard deviation, and interquartile range is concisely explained. The role of geographical information systems and different disease map types is used to demonstrate how disease clusters may be detected. Determining possible association between specific risk factors and outcome is described in the section on analytical epidemiology, using the risk ratio and the odds ratio. The use of these in different study/investigation types is explained. The importance of confounding, matching, and standardization in study design is described. The final part of the chapter covers hypothesis testing to distinguish between real differences and chance variation, and the use of confidence intervals.
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Zinn, S., and S. L. Semiatin. Elements of Induction Heating. ASM International, 1988. http://dx.doi.org/10.31399/asm.tb.eihdca.9781627083416.
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Elements of Induction Heating: Design, Control, and Applications discusses the principles of electromagnetic induction and the setup and use of induction heating processes and equipment. The first few chapters cover the theory of induction heating and the factors that must be considered when selecting and configuring components for a given application. As the text explains, the frequency required for efficient heating is determined by the geometry of the coil, the properties, size, and shape of the workpiece, and the need to maintain adequate skin effect. It also depends on proper tuning and load matching, which is explained as well. Subsequent chapters discuss the use of external cooling, temperature sensing, and power-timing devices, the fundamentals of process control, the role of flux concentrators, shields, and susceptors, and the integration of material handling equipment. The book also covers coil design and fabrication and explains how induction heating systems can be tailored for specific applications such as billet and bar heating, surface hardening, pipe welding, tin reflow, powder metal sintering, and brazing, and for curing adhesives and coatings. For information on the print version, ISBN 978-0-87170-308-8, follow this link.
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Greenberg, Lyn R., Barbara J. Fidler, and Michael A. Saini, eds. Evidence-Informed Interventions for Court-Involved Families. Oxford University Press, 2019. http://dx.doi.org/10.1093/med-psych/9780190693237.001.0001.
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Children at the center of high conflict divorce and/or child protection cases face increased risks to both current and future health and adjustment. There is a growing research base regarding these risks and the coping abilities skills that children need for successful adjustment, but training gaps and poorly structured services continue to be serious problems. The specific characteristics of these families, and risks faced by these children, underscore the importance of treatment, psychoeducation, and other services adapted to this population and directed to minimizing risks and promoting healthy functioning, autonomy, and resilience for these children. This book provides a critical, research-informed analysis of the core factors to include when developing child-centered approaches to therapy and other family interventions, both in the formal treatment setting and promoting healthy engagement with the other systems and activities critical to children’s daily lives. The book addresses common problems, obstacles, and the backdrop of support from other professionals or the court, which may be necessary for successful intervention. An international team of renowned authors provide chapters covering a variety of service models and drawing on a wide range of relevant research and literature, addressing the legal context, central issues for treatment and other services, and specialized issues such as trauma, family violence, parent–child contact problems, and children with special needs. The book assembles in one place the best of what is known about intervention for court-involved families, along with practical guidance for using relevant research, understanding its limitations, and matching service plans to families’ needs.
Book chapters on the topic "Mating a-factor"
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Naider, Fred, P. Shenbagamurthi, Stevan Marcus, and Jeffrey M. Becker. "The a-mating factor of Saccharomyces cerevisiae: A lipopeptide?" In Peptides, 459–61. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-010-9595-2_135.
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Xue, Chu-Biao, Stevan Marcus, Guy A. Caldwell, David Miller, Jeffrey M. Becker, and Fred Naider. "Structure-activity relationships of the Saccharomyces cerevisiae a-mating factor." In Peptides, 899–901. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2264-1_365.
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Yang, Chi-Ching, and Robert Kania. "Total synthesis of the a-mating factor of Saccharomyces cerevisiae." In Peptides 1990, 430–31. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3034-9_181.
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Epand, R. F., C. B. Xue, S. H. Wang, F. Naider, J. M. Becker, and R. M. Epand. "The role of prenylation in the interaction of the a-factor mating pheromone with phospholipid bilayers." In Peptides, 324–26. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0683-2_104.
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Allauzen, Cyril, Maxime Crochemore, and Mathieu Raffinot. "Factor Oracle: A New Structure for Pattern Matching." In SOFSEM’99: Theory and Practice of Informatics, 295–310. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-47849-3_18.
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Chenoweth, Peter. "Applied animal andrology: bull." In Manual of animal andrology, 71–94. Wallingford: CABI, 2022. http://dx.doi.org/10.1079/9781789243505.0006.
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Abstract This chapter describes the factors that affect bull fertility, including, sexual maturity, nutrition, behaviour, libido, mating ability and health, and how to perform a breeding soundness evaluation (measurement of the testes and scrotum, semen characteristics and cryopreservation).
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Albrechtsen, D. "HLA Matching: A Relevant and Scientific Graft Allocation Factor or Only a Crutch?" In Organ Replacement Therapy: Ethics, Justice Commerce, 404–9. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76444-8_62.
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Cao, Ketu, Lixiao Wang, Zhi Zuo, and Xiaohui Sun. "A Map Matching Algorithm Combining Twice Gridding and Weighting Factors Methods." In International Symposium for Intelligent Transportation and Smart City (ITASC) 2019 Proceedings, 63–73. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7542-2_6.
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Opelz, G., and T. Wujciak. "Is HLA Matching a Scientific and Relevant Factor for the Allocation of Cadaver Kidneys?" In Organ Replacement Therapy: Ethics, Justice Commerce, 399–403. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76444-8_61.
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Tadei, Roberto, Federico Della Croce, and Salvatore Pucci. "A Scheduling Prototype for Factory Automation: Matching OR Methodologies to Actual Industrial Needs." In Operational Research in Industry, 183–98. London: Palgrave Macmillan UK, 1999. http://dx.doi.org/10.1057/9780230372924_9.
Full textConference papers on the topic "Mating a-factor"
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Lin, Ah-Der, and Jao-Hwa Kuang. "The Bending and Surface Contact Stress Variations in a Mating Plastic Gear Pair." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34470.
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A dynamic model of an engaging spur gear pair is proposed to study the distributions and variation of bending and surface contact stresses around the fillet and contacting points for plastic gears. The parameters used in this dynamic model include time-varying mesh stiffness, frictional coefficient, and profile-shifted factor, etc. Due to high sensitivity to heat for plastic material, the influence of temperature on plastic gears has also been taken into consideration in this work. A computational algorithm is developed to simulate the variation of fillet bending and surface contact stresses during the engagement with different speeds. The results indicate that the operating temperature may affect the distribution and the magnitude of bending and surface contact stresses of a plastic gear pair significantly.
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Vaziri, A., and H. Nayeb-Hashemi. "Effective Stress Intensity Factor in Mode III Crack Growth in Round Shafts." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-43478.
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Turbine-generator shafts are often subjected to a complex transient torsional loading. Such transient torques may initiate and propagate a circumferential crack in the shafts. Mode III crack growth in turbo-generator shafts often results in a fracture surface morphology resembling a factory roof. The interactions of the mutual fracture surfaces result in a pressure, and a frictional stress field between fracture surfaces when the shaft is subjected to torsion. This interaction reduces the effective Mode III stress intensity factor. The effective stress intensity factor in circumferentially cracked round shafts is evaluated for a wide range of applied torsional loadings by considering a pressure distribution in the mating fracture surfaces. The pressure between fracture surfaces results from climbing the rought surfaces respect to each other. The pressure profile not only depends on the fracture surface roughness (height and width (wavelength) of the peak and valleys), but also depends on the magnitude of the applied Mode III stress intensity factor. The results show that the asperity interactions significantly reduce the effective Mode III stress intensity factor. However, the crack surfaces interaction diminishes beyond a critical applied Mode III stress intensity factor. The critical stress intensity factor depends on the asperities height and wavelength. The results of these analyses are used to find the effective stress intensity factor in various Mode III fatigue crack growth experiments. The results show that Mode III crack growth rate is related to the effective stress intensity factor in a form of the Paris law.
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Warren, Jonah. "Factor: A game about matching common factors." In 2015 IEEE Games Entertainment Media Conference (GEM). IEEE, 2015. http://dx.doi.org/10.1109/gem.2015.7377238.
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Tsai, Jhy-Cherng, and Jing-Sheng Chang. "Development of an AutoCAD-Based Geometric Tolerancing System." In ASME 1997 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/detc97/dac-3998.
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Abstract Geometric tolerancing is an important factor affecting the functional performance and manufacturing cost of a product. Tolerancing specifications have to be assigned with care at design time to reduce the gap between design and manufacturing. This paper describes a system that simplifies tolerancing assignment and uses dimensioning and tolerancing data for related applications. The system consists of five modules for feature type classification, tolerance assignment, tolerance network construction, frame transformation, and tolerance analysis interface. It provides an interactive interface for tolerance assignment based on geometric features that a designer can select from decomposed isometric drawing. The system also recognizes the type of a feature so that only appropriate tolerancing specifications can be assigned. Geometric dimensioning and tolerancing data are used to construct a network for representing the tolerancing and mating relationship among features. The network is then converted for tolerance analysis via a tolerance analysis interface.
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Raffaeli, Roberto, Paolo Cicconi, Maura Mengoni, and Michele Germani. "Modular Product Configuration: An Automatic Tool for Eliciting Design Knowledge From Parametric CAD Models." In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28242.
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The offer of tailored products is a key factor to satisfy specific customer needs in the current competitive market. Modular products can easily support customization in a short time. Design process, in this case, can be regarded as a configuration task where solution is achieved through the combination of modules in overall product architecture. In this scenario efficient configuration design tools are evermore important. Although many tools have been already proposed in literature, they need further investigation to be applicable in real industrial practice, because of the high efforts required to implement system and the lack of flexibility in products updating. This work describes an approach to overcome drawbacks and to introduce a product independent configuration system which can be useful in designing recurrent product modules. To manage configuration from the designer perspective, the approach is based on Configurable Virtual Prototypes (CVP). In particular, the definition of geometrical models is analyzed providing a tool for eliciting and reusing knowledge introduced by parametric template CAD models. Semantic rules are used to recognize parts parameterization and assembly mating constraints. The approach is exemplified through a case study.
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Simon, Vilmos V. "Optimal Machine Tool Setting for Hypoid Gears Improving Load Distribution." In ASME 2000 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/detc2000/ptg-14392.
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Abstract A method for the determination of optimal machine tool setting for manufacturing modified (mismatched) hypoid gears based on improved load distribution and reduced transmission errors is presented. The applied load distribution calculation is based on the conditions that the total angular position errors of the gear teeth being instantaneously in contact under load must be the same, and along the contact line of every tooth pair instantaneously in contact, the composite displacements of tooth surface points — as the sums of tooth deformations, geometrical surface separations, gear body bending and torsion, deflections of the supporting shafts, misalignments, and composite tooth errors — should correspond to the angular position of the gear. The tooth defonnations consists of the bending and shearing deflections of gear teeth and of the local contact deformations of the mating surfaces. The tooth deflections are calculated by the finite element method. As the equations governing the load sharing and load distribution are nonlinear, an approximate and iterative technique is used to solve this system of equations. The method is implemented by a computer program. Using the program that was developed the influence of machine tool setting parameters for pinion manufacture on maximum tooth contact pressure, load distribution factor, and transmission errors is investigated. By successively choosing the optimal value for every machine tool setting parameter, and by applying the optimal set of these parameters, the maximum tooth contact pressure is reduced by 5.8%, the load distribution factor by 5.9%, and the angular position error of the driven gear by 65.4%, in regard to the hypoid gear pair manufactured by the machine tool setting determined by the commonly used method.
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Vaziri, A., H. Nayeb-Hashemi, and H. R. Hamidzadeh. "The Effects of the Crack Surfaces Interaction and the Crack Tip Plasticity on the Dynamic Response of the Circumferentially Cracked Turbo Generator Shafts." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42520.
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Turbo generator shafts are often subjected to complex dynamic torsional loadings, resulting in generation and propagation of circumferential cracks. These cracks can severely affect the vibration characteristics of the shafts. The effects of a circumferential crack, its size and location on the torsional dynamic response of a shaft is obtained, considering the local energy loss at the crack tip due to the cyclic plasticity and the crack surfaces interaction. The crack is taken to be normal to the shaft axis and the shaft is subjected to a harmonic torsional load. The shaft material is assumed to be elastic perfectly plastic. The local flexibility is calculated by evaluating the resistance of the un-cracked region of the shaft to the rotational displacement. The effective damping constant is evaluated by considering the frictional energy loss due to the crack surfaces interaction and energy loss due to the plasticity at the crack tip. The energy loss due to the crack surfaces interaction is evaluated by assuming a pressure distribution between mating fracture surfaces. The pressure distribution parameters are obtained by considering the fracture surface roughness (asperities height and width), and crack opening displacements in Modes I and III. The Energy loss due to the plasticity at the crack tip is related to the plastic zone size. The effects of the applied Mode III stress intensity factor on the energy loss due to the friction and the energy loss due to the plasticity at the crack tip are investigated. The results show that depending on the amplitude of the applied Mode III stress intensity factor, one of these energy losses may dominate the total energy loss. The results further indicate that the vibration characteristics of the shaft are significantly affected by considering these two sources of the local energy loss.
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Raimbay, A., T. Babadagli, E. Kuru, and K. Develi. "Quantitative and Visual Analysis of Proppant Transport in Rough Fractures and Aperture Stability." In SPE Hydraulic Fracturing Technology Conference. SPE, 2015. http://dx.doi.org/10.2118/spe-173385-ms.
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AbstractThe consensus reached in the literature is that the roughness of fractures plays a crucial role on proppant transport affecting the aperture sustainability of hydraulic fractures. In this paper, an experimental scheme to visually and quantitatively investigate the hydraulic characteristics of rough fractures in the presence of proppants was presented. Rock samples of different kinds (i.e., granite, marble, and limestone) were fractured under the Brazilian test and molded to manufacture 20x20 cm transparent replicas. Propping agents were injected in a similar fashion and were introduced into the well with fracking fluid at a constant rate. Two types of fracture models were used: (1) perfectly mating (joint) and (2) sheared fractures in polymeric solutions. During the experiments, the inlet pressure was continuously monitored to quantify the permeability changes due to proppant distribution caused by the roughness of fracture surfaces. Meanwhile, corresponding images were collected to trace the transport of proppants and their behavior was correlated to the measured permeability change. For a better visualization of proppants, the injected fluid was dyed with a fluorescent material.In both joint and shear type fractures, existing closure areas controlled the proppant movement and permeability change significantly. The fracture roughness controlled by the lithological properties of the rocks was a critical factor affecting the permeability and proppant transport. After quantifying the roughness characteristics through the variogram fractal dimension, relationship between fracture permeability in the presence of proppant and rock types were presented. Also provided was a semi-quantitative analysis of the stability (or settlement) of proppants during injection with respect to the roughness type (and lithology). The quantitative and visual data collected for a wide range of rock types with original roughness characteristics are expected to be useful in fracking design and selection of proper proppants for different reservoirs.
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Preve´y, Paul S., N. Jayaraman, Ravi A. Ravindranath, and Michael Shepard. "Mitigation of Fretting Fatigue Damage in Blade and Disk Pressure Faces With Low Plasticity Burnishing." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27424.
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Low Plasticity Burnishing (LPB) is now established as a surface enhancement technology capable of introducing through-thickness compressive residual stresses in the edges of gas turbine engine blades and vanes to mitigate foreign object damage (FOD). The “Fatigue Design Diagram” (FDD) method has been described and demonstrated to determine the depth and magnitude of compression required to achieve the optimum high cycle fatigue (HCF) strength, and to mitigate a given depth of damage characterized by the fatigue stress concentration factor, kf. LPB surface treatment technology and the FDD method have been combined to successfully mitigate a wide variety of surface damage ranging from FOD to corrosion pits in titanium and steel gas turbine engine compressor and fan components. LPB mitigation of fretting induced damage in Ti-6AL-4V in laboratory samples has now been extended to fan and compressor components. LPB tooling technology recently developed to allow the processing of the pressure faces of fan and compressor blade dovetails and mating disk slots is described. Fretting induced micro-cracks that form at the pressure face edge of bedding on both the blade dovetail and the dovetail disk slots in Ti-6-4 compressor components can now be arrested by the introduction of deep stable compression in conventional CNC machine tools during manufacture or overhaul. The compressive residual stress field design method employing the FDD approach developed at Lambda Technologies is described in application to mitigate fretting damage. The depth and magnitude of compression and the fatigue and damage tolerance achieved are presented. It was found that microcracks as deep as 0.030 in., (0.75 mm) large enough to be readily detected by current NDI technology, can be fully arrested by LPB. The depth of compression achieved could allow NDI screening followed by LPB processing of critical components to reliably restore fatigue performance and extend component life.
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Song, Dongcao, Xichang Wang, Yanjun Gong, Shangming Yang, and Fangying Liang. "A new weight factor spectrophotometric computer color matching." In Photonics Asia 2004, edited by Chung-Sheng Li and Minerva M. Yeung. SPIE, 2005. http://dx.doi.org/10.1117/12.573777.
Full textReports on the topic "Mating a-factor"
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Bhakta, Tuhin, Jarle Haukås, Rolf Johan Lorentzen, Xiaodong Luo, and Geir Nævdal. Workflow for adding 4D seismic data in history matching. University of Stavanger, November 2021. http://dx.doi.org/10.31265/usps.204.
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In this document we present a workflow for ensemble-based 4D seismic history matching. Ensemble-based history matching has become standard for production data, but 4D seismic data poses a number of additional challenges. One issue is that the amount of data is considerably larger, but another, probably more complicating factor is that for utilizing the seismic data, either the seismic data must be inverted to properties that is included in the reservoir simulation model, or a seismic response must be modeled, given the current estimate of the reservoir properties. This leads to a number of choices on how to utilize the information of the 4D seismic data. We will discuss this, as well as point to approaches for handling large amounts of data in ensemble-based history matching. The developed approach has been applied on the Norne field and is currently being evaluated at the Ekofisk field. This document is primarily addressed to reservoir engineers and researchers that are working on history matching 4D seismic data, but it might also be of interest to those working with 4D seismic data from a geophysical perspective. After all, 4D seismic history matching should be viewed as an interdisciplinary subject. Although, our focus has been on ensemble-based history matching, some of the choices that have to be made in utilizing 4D seismic data is independent of the actual method used for history matching.
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Mort, A. Controls on the distribution and composition of gas and condensate in the Montney resource play. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329790.
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The Montney resource play has evolved from a peripheral conventional play to one of the most important hydrocarbon-producing unconventional resource plays in North America and has remained resilient throughout the economic challenges of recent years. Despite maturing as a resource play as a result of more than 15 years of unconventional development and research there are still aspects of the play that are not fully de-risked and prediction of fluid quality remains haphazard due to the complex interplay of geological and engineering factors. Among these are the delineation of structural and stratigraphic barriers and conduits, identification of enigmatic source rocks, which defy traditional methods, evaluating effects of fluid migration and the difficulty in predicting phase behavior in a tight, but open system. This study uses a combined approach leveraging geochemical tools combined with spatial and stratigraphic analysis in an attempt to improve current understanding of these issues.
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Chejanovsky, Nor, Diana Cox-Foster, Victoria Soroker, and Ron Ophir. Honeybee modulation of infection with the Israeli acute paralysis virus, in asymptomatic, acutely infected and CCD colonies. United States Department of Agriculture, December 2013. http://dx.doi.org/10.32747/2013.7594392.bard.
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Honey bee (Apis mellifera) colony losses pose a severe risk to the food chain. The IAPV (Israeli acute paralysis virus) was correlated with CCD, a particular case of colony collapse. Honey bees severely infected with IAPV show shivering wings that progress to paralysis and subsequent death. Bee viruses, including IAPV, are widely present in honey bee colonies but often there are no pathological symptoms. Infestation of the beehive with Varroa mites or exposure to stress factors leads to significant increase in viral titers and fatal infections. We hypothesized that the honey bee is regulating/controlling IAPV and viral infections in asymptomatic infections and this control is broken through "stress" leading to acute infections and/or CCD. Our aims were: 1. To discover genetic changes in IAPV that may affect tissue tropism in the host, and/or virus infectivity and pathogenicity. 2. To elucidate mechanisms used by the host to regulate/ manage the IAPV-infection in vivo and in vitro. To achieve the above objectives we first studied stress-induced virus activation. Our data indicated that some pesticides, including myclobutanil, chlorothalonil and fluvalinate, result in amplified viral titers when bees are exposed at sub lethal levels by a single feeding. Analysis of the level of immune-related bee genes indicated that CCD-colonies exhibit altered and weaker immune responses than healthy colonies. Given the important role of viral RNA interference (RNAi) in combating viral infections we investigated if CCD-colonies were able to elicit this particular antiviral response. Deep-sequencing analysis of samples from CCD-colonies from US and Israel revealed high frequency of small interfering RNAs (siRNA) perfectly matching IAPV, Kashmir bee virus and Deformed wing virus genomes. Israeli colonies showed high titers of IAPV and a conserved RNAi pattern of targeting the viral genome .Our findings were further supported by analysis of samples from colonies experimentally infected with IAPV. Following for the first time the dynamics of IAPV infection in a group of CCD colonies that we rescued from collapse, we found that IAPV conserves its potential to act as one lethal, infectious factor and that its continuous replication in CCD colonies deeply affects their health and survival. Ours is the first report on the dominant role of IAPV in CCD-colonies outside from the US under natural conditions. We concluded that CCD-colonies do exhibit a regular siRNA response that is specific against predominant viruses associated with colony losses and other immune pathways may account for their weak immune response towards virus infection. Our findings: 1. Reveal that preventive measures should be taken by the beekeepers to avoid insecticide-based stress induction of viral infections as well as to manage CCD colonies as a source of highly infectious viruses such as IAPV. 2. Contribute to identify honey bee mechanisms involved in managing viral infections.
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Yahav, Shlomo, John Brake, and Orna Halevy. Pre-natal Epigenetic Adaptation to Improve Thermotolerance Acquisition and Performance of Fast-growing Meat-type Chickens. United States Department of Agriculture, September 2009. http://dx.doi.org/10.32747/2009.7592120.bard.
Full textAbstract:
: The necessity to improve broiler thermotolerance and performance led to the following hypothesis: (a) thethermoregulatory-response threshold for heat production can be altered by thermal manipulation (TM) during incubation so as to improve the acquisition of thermotolerance in the post-hatch broiler;and (b) TM during embryogenesis will improve myoblast proliferation during the embryonic and post-hatch periods with subsequent enhanced muscle growth and meat production. The original objectives of this study were as follow: 1. to assess the timing, temperature, duration, and turning frequency required for optimal TM during embryogenesis; 2. to evaluate the effect of TM during embryogenesis on thermoregulation (heat production and heat dissipation) during four phases: (1) embryogenesis, (2) at hatch, (3) during growth, and (4) during heat challenge near marketing age; 3. to investigate the stimulatory effect of thermotolerance on hormones that regulate thermogenesis and stress (T₄, T₃, corticosterone, glucagon); 4. to determine the effect of TM on performance (BW gain, feed intake, feed efficiency, carcass yield, breast muscle yield) of broiler chickens; and 5. to study the effect of TM during embryogenesis on skeletal muscle growth, including myoblast proliferation and fiber development, in the embryo and post-hatch chicks.This study has achieved all the original objectives. Only the plasma glucagon concentration (objective 3) was not measured as a result of technical obstacles. Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” In order to sustain or even improve broiler performance, TM during the period of embryogenesis when satellite cell population normally expand should increase absolute pectoralis muscle weight in broilers post-hatch. Major conclusions: Intermittent TM (39.5°C for 12 h/day) during embryogenesis when the thyroid and adrenal axis was developing and maturing (E7 to E16 inclusive) had a long lasting thermoregulatory effect that improved thermotolerance of broiler chickens exposed to acute thermal stress at market age by lowering their functional Tb set point, thus lowering metabolic rate at hatch, improving sensible heat loss, and significantly decreasing the level of stress. Increased machine ventilation rate was required during TM so as to supply the oxygen required for the periods of increased embryonic development. Enhancing embryonic development was found to be accomplished by a combination of pre-incubation heating of embryos for 12 h at 30°C, followed by increasing incubation temperature to 38°C during the first 3 days of incubation. It was further facilitated by increasing turning frequency of the eggs to 48 or 96 times daily. TM during critical phases of muscle development in the late-term chick embryo (E16 to E18) for 3 or 6 hours (39.5°C) had an immediate stimulatory effect on myoblast proliferation that lasted for up to two weeks post-hatch; this was followed by increased hypertrophy at later ages. The various incubation temperatures and TM durations focused on the fine-tuning of muscle development and growth processes during late-term embryogenesis as well as in post-hatch chickens.
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Yaron, Zvi, Abigail Elizur, Martin Schreibman, and Yonathan Zohar. Advancing Puberty in the Black Carp (Mylopharyngodon piceus) and the Striped Bass (Morone saxatilis). United States Department of Agriculture, January 2000. http://dx.doi.org/10.32747/2000.7695841.bard.
Full textAbstract:
Both the genes and cDNA sequences encoding the b-subunits of black carp LH and FSH were isolated, cloned and sequenced. Sequence analysis of the bcFSHb and LHb5'flanking regions revealed that the promoter region of both genes contains canonical TATA sequences, 30 bp and 17 bp upstream of the transcription start site of FSHb and LHb genes, respectively. In addition, they include several sequences of cis-acting motifs, required for inducible and tissue-specific transcriptional regulation: the gonadotropin-specific element (GSE), GnRH responsive element (GRE), half sites of estrogen and androgen response elements, cAMP response element, and AP1. Several methods have been employed by the Israeli team to purify the recombinant b subunits (EtOH precipitation, gel filtration and lentil lectin). While the final objective to produce pure recombinantGtH subunits has not yet been achieved, we have covered much ground towards this goal. The black carp ovary showed a gradual increase in both mass and oocyte diameter. First postvitellogenic oocytes were found in 5 yr old fish. At this age, the testes already contained spermatozoa. The circulating LH levels increased from 0.5 ng/ml in 4 yr old fish to >5ng/ml in 5 yr old fish. In vivo challenge experiments in black carp showed the initial LH response of the pituitary to GnRH in 4 yr old fish. The response was further augmented in 5 yr old fish. The increase in estradiol level in response to gonadotropic stimulation was first noted in 4 yr old fish but this response was much stronger in the following year. In vivo experiments on the FSHb and LHb mRNA levels in response to GnRH were carried out on common carp as a model for synchronom spawning cyprinids. These experiments showed the prevalence of FSHP in maturing fish while LHP mRNA was prevalent in mature fish, especially in females. The gonadal fat-pad was found to originate from the retroperitoneal mesoderm and not from the genital ridge, thus differing from that reported in certain amphibians This tissue possibly serves as the major source of sex steroids in the immature black carp. However, such a function is taken over by the developing gonads in 4 yr old fish. In the striped bass, we described the ontogeny of the neuro-endocrine parameters along the brain-pituitary-gonadal axis during the first four years of life, throughout gonadal development and the onset of puberty. We also described the responsiveness of the reproductive axis to long-term hormonal manipulations at various stages of gonadal development. Most males reached complete sexual maturity during the first year of life. Puberty was initiated during the third year of life in most females, but this first reproductive cycle did not lead to the acquisition of full sexual maturity. This finding indicates that more than one reproductive cycle may be required before adulthood is reached. Out of the three native GnRHs present in striped bass, only sbGnRH and cGnRH II increased concomitantly with the progress of gonadal development and the onset of puberty. This finding, together with data on GtH synthesis and release, suggests that while sbGnRH and cGnRH II may be involved in the regulation of puberty in striped bass, these neuropeptides are not limiting factors to the onset of puberty. Plasma LH levels remained low in all fish, suggesting that LH plays only a minor role in early gonadal development. This hypothesis was further supported by the finding that experimentally elevated plasma LH levels did not result in the induction of complete ovarian and testicular development. The acquisition of complete puberty in 4 yr old females was associated with a rise in the mRNA levels of all GtH subunit genes, including a 218-fold increase in the mRNA levels of bFSH. mRNA levels of the a and PLH subunits increased only 11- and 8-fold, respectively. Although data on plasma FSH levels are unavailable, the dramatic increase in bFSH mRNA suggests a pivotal role for this hormone in regulating the onset and completion of puberty in striped bass. The hormonal regulation of the onset of puberty and of GtH synthesis and release was studied by chronic administration of testosterone (T) and/or an analog of gonadotropin-releasing hormone (G). Sustained administration of T+G increased the mRNA levels of the PLH subunit to the values characteristic of sexually mature fish, and also increased the plasma levels of LH. However, these changes did not result in the acceleration of sexual maturation. The mRNA levels of the bFSH subunit were slightly stimulated, but remained about 1/10 of the values characteristic of sexually mature fish. It is concluded that the stimulation of FSH gene expression and release does not lead to the acceleration of sexual maturity, and that the failure to sufficiently stimulate the bFSH subunit gene expression may underlie the inability of the treatments to advance sexual maturity. Consequently, FSH is suggested to be the key hormone to the initiation and completion of puberty in striped bass. Future efforts to induce precocious puberty in striped bass should focus on understanding the regulation of FSH synthesis and release and on developing technologies to induce these processes. Definite formulation of hormonal manipulation to advance puberty in the striped bass and the black carp seems to be premature at this stage. However, the project has already yielded a great number of experimental tools of DNA technology, slow-release systems and endocrine information on the process of puberty. These systems and certain protocols have been already utilized successfully to advance maturation in other fish (e.g. grey mullet) and will form a base for further study on fish puberty.