766 research outputs found

    Late-Time Circumstellar Interaction in a Spitzer Selected Sample of Type IIn Supernovae

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    Type IIn supernovae (SNe IIn) are a rare (< 10%) subclass of core-collapse SNe that exhibit relatively narrow emission lines from a dense, pre-existing circumstellar medium (CSM). In 2009, a warm Spitzer survey observed 30 SNe IIn discovered in 2003 - 2008 and detected 10 SNe at distances out to 175 Mpc with unreported late-time infrared emission, in some cases more than 5 years post-discovery. For this single epoch of data, the warm-dust parameters suggest the presence of a radiative heating source consisting of optical/X-ray emission continuously generated by ongoing CSM interaction. Here we present multi-wavelength follow-up observations of this sample of 10 SNe IIn and the well-studied Type IIn SN 2010jl. A recent epoch of Spitzer observations reveals ongoing mid-infrared emission from nine of the SNe in this sample. We also detect three of the SNe in archival WISE data, in addition to SNe 1987A, 2004dj, and 2008iy. For at least five of the SNe in the sample, optical and/or X-ray emission confirms the presence of radiative emission from ongoing CSM interaction. The two Spitzer nondetections are consistent with the forward shock overrunning and destroying the dust shell, a result that places upper limits on the dust-shell size. The optical and infrared observations confirm the radiative heating model and constrain a number of model parameters, including progenitor mass-loss characteristics. All of the SNe in this sample experienced an outburst on the order of tens to hundreds of years prior to the SN explosion followed by periods of less intense mass loss. Although all evidence points to massive progenitors, the variation in the data highlights the diversity in SN IIn progenitor evolution. While these observations do not identify a particular progenitor system, they demonstrate that future, coordinated, multi-wavelength campaigns can constrain theoretical mass-loss models.Comment: 10 pages, 6 figures, accepted to AJ (with comments

    Use of stormwater impoundments near airports by birds recognizedas hazardous to aviation safety

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    Design of privately-owned stormwater impoundments within or near airport siting criteria has received little attention with regard to potential hazards posed to aviation safety. In particular, minimizing use of these impoundments by bird species recognized as hazardous to aviation poses an important challenge. Emergent vegetation, shoreline irregularity, and proximity of other water resources are linked to avian richness and diversity within wetlands, as well as bird use of stormwater impoundments on airports. We predicted also that impoundments with bank slope \u3e20% and those functioning as detention facilities, where water is periodically drawn down, would negatively influence use by birds; and that shoreline-vegetation diversity and local land-use diversity would be positively correlated with use. Over 104 weeks(March 2008 to March 2010), we surveyed bird use of 40 stormwater impoundments in the Auburn-Opelika Metropolitan area, Lee County, AL, USA, typical of privately-owned facilities located within or near airport siting criteria. We quantified local-scale and site-specific parameters possibly affecting bird use and evaluated fit for 17 a priori models relative to detection of 10 individual avian foraging guilds recognized as hazardous to aviation safety. Relative likelihoods of best-approximating models (Akaike weights) ranged from approximately 0.42 to 0.92. Based on best-approximating models for at least five of the 10 guilds, we suggest that broad reduction in use of stormwater impoundments, located within or near airport siting criteria, by bird species hazardous to aviation can be achieved via designs which minimize perimeter, surface area, and the ratio of open water to emergent vegetation

    A Preliminary Study of Microbial Water Quality Related to Food Safety in Recirculating Aquaponic Fish and Vegetable Production Systems

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    This study examines microbial water quality in recirculating aquaponic systems. The pathogens studied were E. coli and Salmonella, and the levels were compared with existing food safety standards

    Noisy Kuramoto-Sivashinsky equation for an erosion model

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    We derive the continuum equation for a discrete model for ion sputtering. We follow an approach based on the master equation, and discuss how it can be truncated to a Fokker-Planck equation and mapped to a discrete Langevin equation. By taking the continuum limit, we arrive at the Kuramoto-Sivashinsky equation with a stochastic noise term.Comment: latex (w/ multicol.sty), 4 pages; to appear in Physical Review E (Oct 1996

    Use of stormwater impoundments near airports by birds recognizedas hazardous to aviation safety

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    Design of privately-owned stormwater impoundments within or near airport siting criteria has received little attention with regard to potential hazards posed to aviation safety. In particular, minimizing use of these impoundments by bird species recognized as hazardous to aviation poses an important challenge. Emergent vegetation, shoreline irregularity, and proximity of other water resources are linked to avian richness and diversity within wetlands, as well as bird use of stormwater impoundments on airports. We predicted also that impoundments with bank slope \u3e20% and those functioning as detention facilities, where water is periodically drawn down, would negatively influence use by birds; and that shoreline-vegetation diversity and local land-use diversity would be positively correlated with use. Over 104 weeks(March 2008 to March 2010), we surveyed bird use of 40 stormwater impoundments in the Auburn-Opelika Metropolitan area, Lee County, AL, USA, typical of privately-owned facilities located within or near airport siting criteria. We quantified local-scale and site-specific parameters possibly affecting bird use and evaluated fit for 17 a priori models relative to detection of 10 individual avian foraging guilds recognized as hazardous to aviation safety. Relative likelihoods of best-approximating models (Akaike weights) ranged from approximately 0.42 to 0.92. Based on best-approximating models for at least five of the 10 guilds, we suggest that broad reduction in use of stormwater impoundments, located within or near airport siting criteria, by bird species hazardous to aviation can be achieved via designs which minimize perimeter, surface area, and the ratio of open water to emergent vegetation

    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

    FCIC memo of staff interview with US Chamber of Commerce

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    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

    A seismological analysis of Delta Scuti stars in the Pleiades cluster

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    A comparison between the oscillation frequencies of six multi-periodic Delta Scuti stars of the Pleiades cluster and the eigenfrequencies of rotating stellar models that match the corresponding stellar parameters has been carried out. The assumption that all the stars considered have some common parameters, such as metallicity, distance or age, is imposed as a constraint. As a result, we have a best fit solution associated with a cluster metallicity of [Fe/H] ~ 0.067, an age between 70x10^6 and 100x10^6 yr and a distance modulus of mv-Mv=5.60-5.70 mag. All the stars were found to oscillate mainly in non-radial, low degree, low order p modes. Estimates of mass and rotation rates for each star are also obtainedComment: 10 pages, 7 figure
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