749 research outputs found
Eddy Current Imaging of Aircraft Using Real Time Image Signal Processing
The increased incidence of aircraft component failures as motivated a reassessment of the NDE methods applied to assure fleet airworthiness. In the past, eddy current testing has been limited by the presence of spurious signals, operator error and the lack of permanent test results. An eddy current system using portable precision scanners and signal analysis techniques developed in the nuclear industry has been applied to aircraft inspections. Using custom designed probes, multifrequency mixing, and digital signal processing, the detection criteria of 10% loss of wall on the interior faying surface and cracks 60 mils (1.5 mm) in length have been accomplished. The subtle nature of these flaw conditions and the presence of interfering signals prompted the need for signal processing techniques. To achieve this objective, real time signal processing that requires a minimum of computation has been implemented in an eddy current C-scan imaging system. The signal processing produces spatial displays of amplitude (in phase or quadrature), magnitude, phase of spatial derivatives of these parameters. Permanent images that are more easily interpretable for flaw detection are thus produced
The conformation of NAD+ bound to lactate dehydrogenase determined by nuclear magnetic resonance with suppression of spin diffusion
Who Believes in Me? The Effect of Student-Teacher Demographic Match on Teacher Expectations
Teachers are an important source of information for traditionally disadvantaged students. However, little is known about how teachers form expectations and whether they are systematically biased. We investigate whether student-teacher demographic mismatch affects high school teachersâ expectations for studentsâ educational attainment. Using a student fixed effects strategy that exploits expectations data from two teachers per student, we find that non-black teachers of black students have significantly lower expectations than do black teachers. These effects are larger for black male students and math teachers. Our findings add to a growing literature on the role of limited information in perpetuating educational attainment gaps
riboviz 2:A flexible and robust ribosome profiling data analysis and visualization workflow
MOTIVATION: Ribosome profiling, or Ribo-seq, is the state-of-the-art method for quantifying protein synthesis in living cells. Computational analysis of Ribo-seq data remains challenging due to the complexity of the procedure, as well as variations introduced for specific organisms or specialized analyses. RESULTS: We present riboviz 2, an updated riboviz package, for the comprehensive transcript-centric analysis and visualization of Ribo-seq data. riboviz 2 includes an analysis workflow built on the Nextflow workflow management system for end-to-end processing of Ribo-seq data. riboviz 2 has been extensively tested on diverse species and library preparation strategies, including multiplexed samples. riboviz 2 is flexible and uses open, documented file formats, allowing users to integrate new analyses with the pipeline. AVAILABILITY AND IMPLEMENTATION: riboviz 2 is freely available at github.com/riboviz/riboviz
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âIâm good, but not that goodâ: digitally-skilled young peopleâs identity in computing
Computers and information technology are fast becoming a part of young peopleâs everyday life. However, there remains a difference between the majority who can use computers and the minority who are computer scientists or professionals. Drawing on 32 semi-structured interviews with digitally-skilled young people (aged 13-19), we explore their views and aspirations in computing, with a focus on the identities and discourses that these youngsters articulate in relation to this field. Our findings suggest that, even among digitally-skilled young people, traditional identities of computing as people who are clever but antisocial still prevail, which can be unattractive for youths, especially girls. Digitally-skilled youths identify with computing in different ways and for different reasons. Most enjoy doing computing but few aspired to being a computer person. Implications of our findings for computing education are discussed, especially the continued need to broaden identities in computing, even for the digitally-skilled
A Model of Continuous Improvement Programme Management
The aim of this study is to identify key management decisions that enable the sustainment of a continuous improvement (CI) initiative. To accomplish this aim, we examine the procedures and practices used by two manufacturing companies for the management of their CI initiatives; one that is successfully sustaining the effectiveness of its CI initiative and another failing to do the same. This research makes two contributions to the conceptual understanding of CI programme management. First, we identify five CI programme management factors that enable the sustainment of a CI initiative. Second, the five factors are incorporated into a new CI programme management model. The model details a âbottom-upâ procedure for the generation of manufacturing performance improvement ideas and the management of their implementation
Parents, individualism and education: three paradigms and four countries
The UN Convention on the Rights of the Child (1989) is an important indicator of the increased global importance of education. It defines the goal of education at the level of the child rather than the state, the community or household. The requirement that each child be treated as an individual who can expect to see their 'personality, talents and mental and physical abilities' fully developed, is an example of the individualism which features in three important theoretical paradigms for understanding the rise of education and training. We compare accounts of the global growth of education produced by functionalism, neoinstitutionalism and political economy with the help of qualitative research on children's experience of parental influences. The research is drawn from semi-structured interviews with millennial graduates in Portugal, Singapore, the United Kingdom, and the United States. It reveals weaknesses in the paradigms which are related to the way each theorises individualism and the role it plays in parental influence on education. The functionalist and neoinstitutionalist conceptions of individualism limit the usefulness of these paradigms for understanding changes in the way families around the world prepare children for education. The political economy paradigm is more promising; however, an approach which identifies only one, neoliberal, version of individualism has limited purchase on international differences in parental influences and the way these influences are changing. An approach which can draw on the contrast between a cognitive individualism associated with neoliberalism, and sentimental individualism which originates in social movements, is more promising.info:eu-repo/semantics/publishedVersio
The fitness cost of mis-splicing is the main determinant of alternative splicing patterns
Background
Most eukaryotic genes are subject to alternative splicing (AS), which may contribute to the production of protein variants or to the regulation of gene expression via nonsense-mediated messenger RNA (mRNA) decay (NMD). However, a fraction of splice variants might correspond to spurious transcripts and the question of the relative proportion of splicing errors to functional splice variants remains highly debated.
Results
We propose a test to quantify the fraction of AS events corresponding to errors. This test is based on the fact that the fitness cost of splicing errors increases with the number of introns in a gene and with expression level. We analyzed the transcriptome of the intron-rich eukaryote Paramecium tetraurelia. We show that in both normal and in NMD-deficient cells, AS rates strongly decrease with increasing expression level and with increasing number of introns. This relationship is observed for AS events that are detectable by NMD as well as for those that are not, which invalidates the hypothesis of a link with the regulation of gene expression. Our results show that in genes with a median expression level, 92â98% of observed splice variants correspond to errors. We observed the same patterns in human transcriptomes and we further show that AS rates correlate with the fitness cost of splicing errors.
Conclusions
These observations indicate that genes under weaker selective pressure accumulate more maladaptive substitutions and are more prone to splicing errors. Thus, to a large extent, patterns of gene expression variants simply reflect the balance between selection, mutation, and drift
Large introns in relation to alternative splicing and gene evolution: a case study of Drosophila bruno-3
Background:
Alternative splicing (AS) of maturing mRNA can generate structurally and functionally distinct transcripts from the same gene. Recent bioinformatic analyses of available genome databases inferred a positive correlation between intron length and AS. To study the interplay between intron length and AS empirically and in more detail, we analyzed the diversity of alternatively spliced transcripts (ASTs) in the Drosophila RNA-binding Bruno-3 (Bru-3) gene. This gene was known to encode thirteen exons separated by introns of diverse sizes, ranging from 71 to 41,973 nucleotides in D. melanogaster. Although Bru-3's structure is expected to be conducive to AS, only two ASTs of this gene were previously described.
Results:
Cloning of RT-PCR products of the entire ORF from four species representing three diverged Drosophila lineages provided an evolutionary perspective, high sensitivity, and long-range contiguity of splice choices currently unattainable by high-throughput methods. Consequently, we identified three new exons, a new exon fragment and thirty-three previously unknown ASTs of Bru-3. All exon-skipping events in the gene were mapped to the exons surrounded by introns of at least 800 nucleotides, whereas exons split by introns of less than 250 nucleotides were always spliced contiguously in mRNA. Cases of exon loss and creation during Bru-3 evolution in Drosophila were also localized within large introns. Notably, we identified a true de novo exon gain: exon 8 was created along the lineage of the obscura group from intronic sequence between cryptic splice sites conserved among all Drosophila species surveyed. Exon 8 was included in mature mRNA by the species representing all the major branches of the obscura group. To our knowledge, the origin of exon 8 is the first documented case of exonization of intronic sequence outside vertebrates.
Conclusion:
We found that large introns can promote AS via exon-skipping and exon turnover during evolution likely due to frequent errors in their removal from maturing mRNA. Large introns could be a reservoir of genetic diversity, because they have a greater number of mutable sites than short introns. Taken together, gene structure can constrain and/or promote gene evolution
The ideal job-seeker norm: unemployment and marital privileges in the professional middle-class
Objective: To understand how heterosexual US married parents interpret and respond to a spouse's unemployment and subsequent job-searching. Background: The pervasiveness of employment uncertainty, and unemployment, may propel families to embrace gender egalitarian norms. Quantitative research finds that this possibility is not borne out. Qualitative research has sought to illuminate mechanisms as to how gender norms persist even during a time that is optimal for dismantling them, but these mechanisms remain unclear. Method: Seventy-two in-depth interviews were conducted with a nonrandom sample of heterosexual, professional, dual-earner, married, unemployed women, men, and their spouses in the United States. Follow-up interviews were conducted with 35 participants. Intensive family observations were conducted with four families, two of unemployed men, and two of unemployed women. Results: Unemployed women, men, and spouses acknowledge that a set of time-intensive activities are key for reemployment (the ideal job-seeker norm). Couples with unemployed men direct resources such as time, space, and even money to facilitate unemployed men's compliance with the ideal job-seeker norm. Couples downplay the importance of women's reemployment and do not direct similar resources to help unemployed women job-search. Conclusion: Couples preserve a traditional gender status quo, often in defiance of material realities, by actively maintaining men's position at the helm of paid work and women's at unpaid work. Implications: Linking unemployment and job-seeking with the institution of heterosexual marriage reveals novel insights into social and marital processes shaping job-seeking
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