512 research outputs found

    Kinematics and physical conditions of HI in nearby radio sources. The last survey of the old Westerbork Synthesis Radio Telescope

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    We present an analysis of the properties of neutral hydrogen (HI) in 248 nearby (0.0230mJyandforwhichopticalspectroscopyisavailable.TheobservationswerecarriedoutwiththeWesterborkSynthesisRadioTelescopeasthelastlargeprojectbeforetheupgradeofthetelescopewithphasedarrayfeedreceivers(Apertif).Thesamplecoversalmostfourordersofmagnitudeinradiopowerfrom mJy and for which optical spectroscopy is available. The observations were carried out with the Westerbork Synthesis Radio Telescope as the last large project before the upgrade of the telescope with phased array feed receivers (Apertif). The sample covers almost four orders of magnitude in radio power from \log\,P_{\rm 1.4 \,GHz}=22.5WHz W Hz^{-1}and and 26.2WHz W Hz^{-1}.WedetectHIinabsorptionin. We detect HI in absorption in 27\% \pm 5.5\%oftheobjects.ThedistributionandkinematicsoftheabsorbingHIgasappeartodependonradiopower,thepropertiesoftheradiocontinuumemission,andthedustcontentofthesources.AmongthesourceswhereHIisdetected,gaswithkinematicsdeviatingfromregularrotationismorelikelyfoundastheradiopowerincreases.Inthesecases,theHIprofileisoftenasymmetricwithasignificantblue−shiftedcomponent.Thisisparticularlycommonforsourceswith of the objects. The distribution and kinematics of the absorbing HI gas appear to depend on radio power, the properties of the radio continuum emission, and the dust content of the sources. Among the sources where HI is detected, gas with kinematics deviating from regular rotation is more likely found as the radio power increases. In these cases, the HI profile is often asymmetric with a significant blue-shifted component. This is particularly common for sources with \log\,P_{\rm 1.4 \, GHz}>24WHz W Hz^{-1},wheretheradioemissionissmall,possiblybecausetheseradiosourcesareyoung.Thesameisfoundforsourcesthatarebrightinthemid−infrared,i.e.sourcesrichinheateddust.Inthesesources,theHIisoutflowinglikelyundertheeffectoftheinteractionwiththeradioemission.Conversely,indust−poorgalaxies,andinsourceswithextendedradioemission,atallradiopowersweonlydetectHIdistributedinarotatingdisk.StackingexperimentsshowthatinsourcesforwhichwedonotdetectHIinabsorptiondirectly,theHIhasacolumndensitythatislowerthan, where the radio emission is small, possibly because these radio sources are young. The same is found for sources that are bright in the mid-infrared, i.e. sources rich in heated dust. In these sources, the HI is outflowing likely under the effect of the interaction with the radio emission. Conversely, in dust-poor galaxies, and in sources with extended radio emission, at all radio powers we only detect HI distributed in a rotating disk. Stacking experiments show that in sources for which we do not detect HI in absorption directly, the HI has a column density that is lower than 3.5\times 10^{17} (T_{ \rm spin}/c_f)cm cm^{-2}$. We use our results to predict the number and type of HI absorption lines that will be detected by the upcoming surveys of the Square Kilometre Array precursors and pathfinders (Apertif, MeerKAT, and ASKAP).Comment: 22 pages, 15 figures, 4 tables, accepted for publication in A&

    Validity of Simpson-Angus Scale (SAS) in a naturalistic schizophrenia population

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    BACKGROUND: Simpson-Angus Scale (SAS) is an established instrument for neuroleptic-induced parkinsonism (NIP), but its statistical properties have been studied insufficiently. Some shortcomings concerning its content have been suggested as well. According to a recent report, the widely used SAS mean score cut-off value 0.3 of for NIP detection may be too low. Our aim was to evaluate SAS against DSM-IV diagnostic criteria for NIP and objective motor assessment (actometry). METHODS: Ninety-nine chronic institutionalised schizophrenia patients were evaluated during the same interview by standardised actometric recording and SAS. The diagnosis of NIP was based on DSM-IV criteria. Internal consistency measured by Cronbach's α, convergence to actometry and the capacity for NIP case detection were assessed. RESULTS: Cronbach's α for the scale was 0.79. SAS discriminated between DSM-IV NIP and non-NIP patients. The actometric findings did not correlate with SAS. ROC-analysis yielded a good case detection power for SAS mean score. The optimal threshold value of SAS mean score was between 0.65 and 0.95, i.e. clearly higher than previously suggested threshold value. CONCLUSION: We conclude that SAS seems a reliable and valid instrument. The previously commonly used cut-off mean score of 0.3 has been too low resulting in low specificity, and we suggest a new cut-off value of 0.65, whereby specificity could be doubled without loosing sensitivity

    An Investigation into the Impact of Acute Stress on Encoding in Older Adults

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    Acute psychological stress commonly occurs in young and older adults’ lives. Though several studies have examined the influence of stress on how young adults learn new information, the present study is the first to directly examine these effects in older adults. Fifty older adults (M age = 71.9) were subjected to either stress induction or a control task before learning two types of information: a short video and a series of pictures. Twenty-four hours later, they were exposed to misleading information about the video and then completed memory tests for the video and pictures. Heart rate and cortisol measures suggest that a physiological stress response was successfully induced. Though pre-encoding stress had little impact on memory accuracy, stress did influence errors of omission on the cued recall test for the video. Findings are discussed in the context of previous research examining the effects of stress on memory in older adults

    Bioturbation by echidna (Tachyglossus aculeatus) in a forest habitat, South-Western Australia

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    Bioturbation by digging animals is important for key forest ecosystem processes such as soil turnover, decomposition, nutrient cycling, water infiltration, seedling recruitment, and fungal dispersal. Despite their widespread geographic range, little is known about the role of the short-beaked echidna (Tachyglossus aculeatus) in forest ecosystems. We measured the density and size of echidna diggings in the Northern Jarrah Forest, south-western Australia, to quantify the contribution echidna make to soil turnover. We recorded an overall density of 298 echidna diggings per hectare, 21 % of which were estimated to be less than 1 month old. The average size of digs was 50 ± 25 mm in depth and 160 ± 61 mm in length. After taking into account seasonal digging rates, we estimated that echidnas turn over 1.23 tonnes of soil ha-1 year-1 in this forest, representing an important role in ecosystem dynamics. Our work contributes to the growing body of evidence quantifying the role of these digging animals as critical ecosystem engineers. Given that the echidna is the only Australian digging mammal not severely impacted by population decline or range reduction, its functional contribution to health and resilience of forest ecosystems is increasingly important due to the functional loss of most Australian digging mammals

    Trust and control interrelations: New perspectives on the trust control nexus

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    This article is the post-print version of the published article that may be accessed at the link below. Copyright @ 2007 Sage Publications.This article introduces the special issue on New Perspectives on the Trust-Control Nexus in Organizational Relations. Trust and control are interlinked processes commonly seen as key to reach effectiveness in inter- and intraorganizational relations. The relation between trust and control is, however, a complex one, and research into this relation has given rise to various and contradictory interpretations of how trust and control relate. A well-known discussion is directed at whether trust and control are better conceived as substitutes, or as complementary mechanisms of governance. The articles in this special issue bring the discussion on the relationship between both concepts a step further by identifying common factors, distinctive mechanisms, and key implications relevant for theory building and empirical research. By studying trust and control through different perspectives and at different levels of analysis, the articles provide new theoretical insights and empirical evidence on the foundations of the trust-control interrelations

    Rat interleukin-2-activated natural killer (A-NK) cell-mediated lysis is determined by the presence of CD18 on A-NK cells and the absence of major histocompatibility complex class I on target cells

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    The precise mechanism by which target cells are recognized and subsequently lysed by interleukin-2-activated natural killer (A-NK) cells is poorly understood. In this study the role of major histocompatibility complex (MHC) class I and adhesion molecules in the recognition and lysis of tumor cells was investigated in a syngeneic Wag rat model. Preincubation of tumor cells with F(abâ€Č)2 fragments of anti-MHC class I monoclonal antibody (mAb) OX18 strongly enhanced the A-NK cell-mediated lysis. Also normal syngeneic cells such as T cells and A-NK cells became highly sensitive for lysis by A-NK cells after preincubation with mAb OX18. Two other mAb against MHC class I had no effect on lysis of target cells. These data indicate that masking of MHC class I on syngeneic tumor and normal cells by mAb OX18 is sufficient for A-NK cells to recognize target cells as non-self, resulting in lysis. In addition, we found that the presence of mAb against the ÎČ2 (CD18)-integrins blocked the lysis of all tumor cell lines by A-NK cells in 51Cr-release assays, also when target cells were preincubated with mAb OX18. Because of the absence of CD18 on most tumor cells we concluded that a CD18-associated integrin on A-NK cells is essential for lysis of target cells. These results show that in this syngeneic rat model CD18 on A-NK cells together with MHC class I on tumor cells determine A-NK cell-mediated lysis. Furthermore, we hypothesize that the anti-MHC class I OX18 recognizes an epitope on rat MHC class I which is, or is very close to, the restriction element determining A-NK cell-mediated lysis
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