1,740 research outputs found

    Vibration limiting of rotors by feedback control

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    Experimental findings of a three mass rotor with four channels of feedback control are reported. The channels are independently controllable with force being proportional to the velocity and/or instantaneous displacement from equilibrium of the shaft at the noncontacting probe locations (arranged in the vertical and horizontal attitudes near the support bearings). The findings suggest that automatic feedback control of rotors is feasible for limiting certain vibration levels. Control of one end of a rotor does afford some predictable vibration limiting of the rotor at the other end

    Success of organ donation after out-of-hospital cardiac death and the barriers to its acceptance

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    It is well documented that transplants save lives and improve quality of life for patients suffering from kidney, liver, and heart failure. Uncontrolled donation after cardiac death (UDCD) is an effective and ethical alternative to existing efforts towards increasing the available pool of organs. However, people who die from an out-of-hospital cardiac arrest are currently being denied the opportunity to be organ donors except in those few locations where out-of-hospital UDCD programs are active, such as in Paris, Madrid, and Barcelona. Societies have the medical and moral obligation to develop UDCD programs

    Exact results for nucleation-and-growth in one dimension

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    We study statistical properties of the Kolmogorov-Avrami-Johnson-Mehl nucleation-and-growth model in one dimension. We obtain exact results for the gap density as well as the island distribution. When all nucleation events occur simultaneously, the island distribution has discontinuous derivatives on the rays x_n(t)=nt, n=1,2,3... We introduce an accelerated growth mechanism where the velocity increases linearly with the island size. We solve for the inter-island gap density and show that the system reaches complete coverage in a finite time and that the near-critical behavior of the system is robust, i.e., it is insensitive to details such as the nucleation mechanism.Comment: 9 pages, revtex, also available from http://arnold.uchicago.edu/~ebn

    Managing and resisting ‘degeneration’ in employee-owned businesses: a comparative study of two large retailers in Spain and the UK

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    Employee-owned businesses have recently enjoyed a resurgence of interest as possible ‘alternatives’ to the somewhat tarnished image of conventional investor-owned capitalist firms. Within the context of global economic crisis, such alternatives seem newly attractive. This is somewhat ironic because, for more than a century, academic literature on employee-owned businesses has been dominated by the ‘degeneration thesis’. This suggested that these businesses tend towards failure – they either fail commercially, or they relinquish their democratic characters. Bucking this trend and offering a beacon - especially in the UK - has been the commercially successful, co-owned enterprise of the John Lewis Partnership (JLP) whose virtues have seemingly been rewarded with favourable and sustainable outcomes. This paper makes comparisons between JLP and its Spanish equivalent Eroski – the supermarket group which is part of the Mondragon cooperatives. The contribution of this paper is to examine in a comparative way how the managers in JLP and Eroski have constructed and accomplished their alternative scenarios. Using longitudinal data and detailed interviews with senior managers in both enterprises it explores the ways in which two large, employee-owned, enterprises reconcile apparently conflicting principles and objectives. The paper thus puts some new flesh on the ‘regeneration thesis’

    An exploratory cluster randomised trial of a university halls of residence based social norms marketing campaign to reduce alcohol consumption among 1st year students

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    <p>Aims: This exploratory trial examines the feasibility of implementing a social norms marketing campaign to reduce student drinking in universities in Wales, and evaluating it using cluster randomised trial methodology.</p> <p>Methods: Fifty residence halls in 4 universities in Wales were randomly assigned to intervention or control arms. Web and paper surveys were distributed to students within these halls (n = 3800), assessing exposure/contamination, recall of and evaluative responses to intervention messages, perceived drinking norms and personal drinking behaviour. Measures included the Drinking Norms Rating Form, the Daily Drinking Questionnaire and AUDIT-C.</p> <p>Results: A response rate of 15% (n = 554) was achieved, varying substantially between sites. Intervention posters were seen by 80% and 43% of students in intervention and control halls respectively, with most remaining materials seen by a minority in both groups. Intervention messages were rated as credible and relevant by little more than half of students, though fewer felt they would influence their behaviour, with lighter drinkers more likely to perceive messages as credible. No differences in perceived norms were observed between intervention and control groups. Students reporting having seen intervention materials reported lower descriptive and injunctive norms than those who did not.</p> <p>Conclusions: Attention is needed to enhancing exposure, credibility and perceived relevance of intervention messages, particularly among heavier drinkers, before definitive evaluation can be recommended. A definitive evaluation would need to consider how it would achieve sufficient response rates, whilst hall-level cluster randomisation appears subject to a significant degree of contamination.</p&gt

    The adaptation of the Affective Norms for English Words (ANEW) for European Portuguese

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    This study presents the adaptation of the Affective Norms for English Words (ANEW; Bradley & Lang, 1999a) for European Portuguese (EP). The EP adaptation of the ANEW was based on the affective ratings made by 958 college students who were EP native speakers. Participants assessed about 60 words by considering the affective dimensions of valence, arousal, and dominance, using the Self-Assessment Manikin (SAM) in either a paper-and-pencil and a web survey procedures. Results of the adaptation of the ANEW for EP are presented. Furthermore, the differences between EP, American (Bradley & Lang, 1999a), and Spanish (Redondo, Fraga, Padrón, & Comesaña, 2007) standardizations were explored. Results showed that the ANEW words were understood in a similar way by EP, American, and Spanish subjects, although some sex and cross-cultural differences were observed. The EP adaptation of the ANEW is shown to be a valid and useful tool that will allow researchers to control and/or manipulate the affective properties of stimuli as well as to develop cross-linguistic studies. The normative values of EP adaptation of the ANEW can be downloaded at http://brm.psychonomic-journals.org/content/supplemental.COMPETE - Programa Operacional Factores de CompetitividadeFundo Europeu de Desenvolvimento Regional - FEDERQuadro de Referência Estratégico Nacional - QRENFundação para a Ciência e a Tecnologia (FCT) - research project “Procura Palavras (P-Pal ): A software program for deriving objective and subjective psycholinguistic indices for European Portuguese words

    Neural correlates of enhanced visual short-term memory for angry faces: An fMRI study

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    Copyright: © 2008 Jackson et al.Background: Fluid and effective social communication requires that both face identity and emotional expression information are encoded and maintained in visual short-term memory (VSTM) to enable a coherent, ongoing picture of the world and its players. This appears to be of particular evolutionary importance when confronted with potentially threatening displays of emotion - previous research has shown better VSTM for angry versus happy or neutral face identities.Methodology/Principal Findings: Using functional magnetic resonance imaging, here we investigated the neural correlates of this angry face benefit in VSTM. Participants were shown between one and four to-be-remembered angry, happy, or neutral faces, and after a short retention delay they stated whether a single probe face had been present or not in the previous display. All faces in any one display expressed the same emotion, and the task required memory for face identity. We find enhanced VSTM for angry face identities and describe the right hemisphere brain network underpinning this effect, which involves the globus pallidus, superior temporal sulcus, and frontal lobe. Increased activity in the globus pallidus was significantly correlated with the angry benefit in VSTM. Areas modulated by emotion were distinct from those modulated by memory load.Conclusions/Significance: Our results provide evidence for a key role of the basal ganglia as an interface between emotion and cognition, supported by a frontal, temporal, and occipital network.The authors were supported by a Wellcome Trust grant (grant number 077185/Z/05/Z) and by BBSRC (UK) grant BBS/B/16178

    Rampant gene rearrangement and haplotype hypervariation among nematode mitochondrial genomes

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    Rare syntenic conservation, sequence duplication, and the use of both DNA strands to encode genes are signature architectural features defining mitochondrial genomes of enoplean nematodes. These characteristics stand in contrast to the more conserved mitochondrial genome sizes and transcriptional organizations of mitochondrial DNAs (mtDNAs) derived from chromadorean nematodes. To address the frequency of gene rearrangement within nematode mitochondrial DNA (mtDNA), mitochondrial genome variation has been characterized within a more confined enoplean taxonomic unit, the family Mermithidae. The complete nucleotide sequences of the mosquito parasitic nematodes Romanomermis culicivorax, R. nielseni, and R. iyengari mtDNA have been determined. Duplicated expanses encompassing different regions of the mitochondrial genomes were found in each of these congeners. These mtDNA shared few rRNA and protein gene junctions, indicating extensive gene rearrangement within the Romanomermis lineage. Rapid structural changes are also observed at the conspecific level where no two individual nematodes carry the same haplotype. Rolling circle amplification was used to isolate complete mitochondrial genomes from individuals in local populations of Thaumamermis cosgrovei, a parasite of terrestrial isopods. Mitochondrial DNA length variants ranging from 19 to 34 kb are observed, but haplotypes are not shared between any two individuals. The complete nucleotide sequences of three haplotypes have been determined, revealing a constant region encoding most mitochondrial genes and a hypervariable segment that contains intact and pseudogene copies of several mitochondrial genes, duplicated to different copy numbers, resulting in mtDNA size variation. Constant rearrangement generates new T. cosgrovei mtDNA forms

    Object Detection Through Exploration With A Foveated Visual Field

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    We present a foveated object detector (FOD) as a biologically-inspired alternative to the sliding window (SW) approach which is the dominant method of search in computer vision object detection. Similar to the human visual system, the FOD has higher resolution at the fovea and lower resolution at the visual periphery. Consequently, more computational resources are allocated at the fovea and relatively fewer at the periphery. The FOD processes the entire scene, uses retino-specific object detection classifiers to guide eye movements, aligns its fovea with regions of interest in the input image and integrates observations across multiple fixations. Our approach combines modern object detectors from computer vision with a recent model of peripheral pooling regions found at the V1 layer of the human visual system. We assessed various eye movement strategies on the PASCAL VOC 2007 dataset and show that the FOD performs on par with the SW detector while bringing significant computational cost savings.Comment: An extended version of this manuscript was published in PLOS Computational Biology (October 2017) at https://doi.org/10.1371/journal.pcbi.100574
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