905 research outputs found

    Single stage, low noise advanced technology fan. Volume 3: Acoustic design

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    The acoustic design for a half-scale fan vehicle, which would have application on an advanced transport aircraft, is described. The single stage advanced technology fan was designed to a pressure ratio of 1.8 at a tip speed of 503 m/sec (1,650 ft/sec). The two basic approaches taken in the acoustic design were: (1) minimization of noise at the source, and (2) suppression of the generated noise in the inlet and bypass exhaust duct. Suppression of the generated noise is accomplished in the inlet through use of the hybrid concept (wall acoustic treatment plus airflow acceleration suppression) and in the exhaust duct with extensive acoustic treatment including a splitter. The goal of the design was attainment of twenty effective perceived noise decibels (20 EPNdB) below current Federal Air Regulation noise standards for a full-scale fan at the takeoff, cutback, and approach conditions. Predicted unsuppressed and suppressed fore and aft maximum perceived noise levels indicate that the cutback condition is the most critical with respect to the goal, which is probably unattainable for that condition. This is also true for aft radiated noise in the approach condition

    Does the Redundant Signals Effect Occur with Categorical Signals?

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    The redundant signals effect (RSE) refers to a decrease in response time (RT) when multiple signals are present compared to when one signal is present. The RSE is widespread when responses are made to specific signals; for example, a participant who is asked to respond to the letter “N” will respond more quickly to two “Ns” than to one “N.” The current research was conducted to determine whether or not the RSE generalizes to categorical signals. In Experiment 1, participants pressed a button when they saw any number on a computer screen. Each trial contained two stimuli subtending 1º visual angle and placed 3º above and below the center of the screen. Both stimuli were letters on 50% of trials (no-signal condition), one stimulus was a number on 25% of trials (single-signal condition), and both stimuli were numbers on 25% of trials (redundant-signal condition). RT was faster in the redundant-signal condition (461 ms) than in the single-signal condition (509 ms, p \u3c .001), indicating that the RSE occurred. However, Experiment 1 contained noise (a letter) in the single-signal condition; when the noise letter was removed in Experiment 2, the RSE was nonsignificant (redundant-signal RT = 446, single-signal RT = 458 ms, p = .167). Nevertheless, the trend in Experiment 2 was towards a RSE, and the fast RTs may indicate a ceiling effect. For now, the evidence in favor of a categorical RSE is mixed; further research is expected to provide clarity on the issue

    Redundant Signals in the Triple Conjunction Effect

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    The triple conjunction effect (TCE) is characterized by faster response times (RT) when a target is defined by three features than when it is defined by three features. Similarly, the redundant signals effect (RSE) is characterized by faster RTs when a display contains multiple features that are each sufficient to define a target. When a single display element contains multiple target features in separate feature dimensions, the RSE may be attributable to feature coactivation, in which information from multiple features combines to reach a response threshold. Because triple conjunctions contain an extra distinguishing feature, they are comparable to the RSE, and feature coactivation may therefore be expected. In the current study, participants searched for the presence of a target letter in 4 blocks of conjunction search trials (2 of color and orientation, and 2 of form and orientation) and 2 blocks of triple conjunction search trials (color, form, and orientation). Each trial contained 4 or 8 letters subtending 2° by 2° on an invisible circle 8° from the center of the display. Trials were terminated if participants moved their eyes more than 2.75° from the center or did not respond within 4 seconds. A similar second experiment was conducted with distractor homogeneity equated across conjunction and triple conjunction searches. Results indicated that the TCE occurred in both experiments; RTs were ~206 ms faster in triple conjunction than conjunction search. The Townsend Bound, a theoretical minimum for triple conjunction RT under the assumption that no coactivation occurred, was violated at several quantiles (5-16 of 18 quantiles, depending on experiment, set size, and target) when RT was averaged across participants. Additionally, most participants individually violated the Townsend Bound in at least some conditions, providing further evidence for coactivation. The results suggest that the TCE is at least partially due to coactivation of target-relevant features

    Evolution of the major moss lineages: phylogenetic analyses based on multiple gene sequences and morphology

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    Evolutionary relationships of mosses are still poorly understood, with family, order, and subclass circumscription and relationships remaining especially obscure

    Chloroplast Genome Sequence of the Moss Torula ruralis: Gene Content, Polymorphism, and Structural Arrangement Relative to Other Green Plant Chloroplast Genomes

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    Background Tortula ruralis, a widely distributed species in the moss family Pottiaceae, is increasingly used as a model organism for the study of desiccation tolerance and mechanisms of cellular repair. In this paper, we present the chloroplast genome sequence of T. ruralis, only the second published chloroplast genome for a moss, and the first for a vegetatively desiccation-tolerant plant. Results The Tortula chloroplast genome is ~123,500 bp, and differs in a number of ways from that of Physcomitrella patens, the first published moss chloroplast genome. For example, Tortula lacks the ~71 kb inversion found in the large single copy region of the Physcomitrella genome and other members of the Funariales. Also, the Tortula chloroplast genome lacks petN, a gene found in all known land plant plastid genomes. In addition, an unusual case of nucleotide polymorphism was discovered. Conclusions Although the chloroplast genome of Tortula ruralis differs from that of the only other sequenced moss, Physcomitrella patens, we have yet to determine the biological significance of the differences. The polymorphisms we have uncovered in the sequencing of the genome offer a rare possibility (for mosses) of the generation of DNA markers for fine-level phylogenetic studies, or to investigate individual variation within population

    Family systems and mental health issues: A resilience approach

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    In many cases the consumers of mental health information and support are the families of mental health sufferers. The aim of the project was to understand resilience in people who live with or support a family member with a diagnosed or undiagnosed mental illness. Participants were 15 carers (one male, 14 female). Semi-structured interviews were transcribed and analysed using content analysis. Eight recurring themes emerged which indicated the challenges the carers faced and provided indications of the positive and negative personal, family and social factors that impacted on their lives. These themes were \u27Getting to CLAN WA\u27, \u27Accessing help including CLAN WA\u27, \u27Impact of living with a person who has a mental illness or problematic behaviour\u27, \u27Family and cultural issues\u27, \u27Communication within the family\u27,\u27Coping strategies and evidence of resilience\u27, \u27Social support\u27 and \u27Notion of sacrifice\u27. There is still considerable work to do in supporting people who live with or support a family member in these circumstances. The findings demonstrate that individuals living with adversity can do more than just survive the proces

    Complete Plastome Sequences of Equisetum arvense and Isoetes flaccida: Implications for Phylogeny and Plastid Genome Evolution of Early Land Plant Lineages

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    Background Despite considerable progress in our understanding of land plant phylogeny, several nodes in the green tree of life remain poorly resolved. Furthermore, the bulk of currently available data come from only a subset of major land plant clades. Here we examine early land plant evolution using complete plastome sequences including two previously unexamined and phylogenetically critical lineages. To better understand the evolution of land plants and their plastomes, we examined aligned nucleotide sequences, indels, gene and nucleotide composition, inversions, and gene order at the boundaries of the inverted repeats. Results We present the plastome sequences of Equisetum arvense, a horsetail, and of Isoetes flaccida, a heterosporous lycophyte. Phylogenetic analysis of aligned nucleotides from 49 plastome genes from 43 taxa supported monophyly for the following clades: embryophytes (land plants), lycophytes, monilophytes (leptosporangiate ferns + Angiopteris evecta + Psilotum nudum + Equisetum arvense), and seed plants. Resolution among the four monilophyte lineages remained moderate, although nucleotide analyses suggested that P. nudum and E. arvense form a clade sister to A. evecta + leptosporangiate ferns. Results from phylogenetic analyses of nucleotides were consistent with the distribution of plastome gene rearrangements and with analysis of sequence gaps resulting from insertions and deletions (indels). We found one new indel and an inversion of a block of genes that unites the monilophytes. Conclusions Monophyly of monilophytes has been disputed on the basis of morphological and fossil evidence. In the context of a broad sampling of land plant data we find several new pieces of evidence for monilophyte monophyly. Results from this study demonstrate resolution among the four monilophytes lineages, albeit with moderate support; we posit a clade consisting of Equisetaceae and Psilotaceae that is sister to the true ferns, including Marattiaceae

    Embedding reflexivity within experiential qualitative psychology

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    In this article, it is argued that reflexivity is integral to experiential qualitative research in psychology. Reflexivity has been defined in many ways. Woolgar’s continuum of reflexivity though provides a useful gauge by which to judge whether a researcher is involved in simple reflection or reflexivity. The article demonstrates the benefits of adopting a reflexive attitude by presenting “challenge-to-competency.” The author’s encounter with Sarah will help illustrate the role of reflexivity both in data generation and in interpretative analysis. To close, it is proposed that reflexivity as hermeneutic reflection, with its grounding in hermeneutics and phenomenology, is a useful construct for guiding our engagement in reflexivity in experiential qualitative research

    Playing in the academic field: Non-native English-speaking academics in UK business schools

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    This paper draws on Bourdieu's concepts of field, habitus and capital to explore the ways in which working in English as a non-native language influences foreign academics' performance of academic habitus and the level of their symbolic capital necessary for the achievement of success within UK higher education. Empirically, it is based on interviews with 54 non-native English-speaking academics employed in UK business schools. Our findings point to advantages and disadvantages associated with being a non-native English-speaking academic, to strategies deployed by individuals to enhance their linguistic capital, and to the importance of language not merely as a tool of communication but as a key factor enabling individuals to perform academic habitus in the UK academic field. We reflect on whether, and if so, how, the UK academic field is changing as a result of the increased presence within it of non-UK-born academics and, in particular, the fact of their professional functioning in English as a non-native language
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