536 research outputs found

    Evolving empowerment in an online community collection memories of Amsterdam East

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    In this article we study the evolvement of empowering and dis-empowering aspects of a local memory website, initiated by the Amsterdam Museum and currently active for more than a decade. The results partly fill a gap in the available literature about this field, because the relation between collective empowerment and online behaviour in these communities has been underexposed. Departing from a narrative perspective on memories as resources for empowerment, we show how the online dynamics around these memories exhibit collective processes of identity formation, social learning and networking. However, certain patterns in the online dynamics also uncover that, although the online activity is increasing, the diversity in the content and the number of participants are decreasing. Describing the organizational development of the local memory community, we argue that the growth into a self-organizing community is the cause of increasing activity and decreasing participation. This implies that the online community has become a small, empowered group, which at the same time has developed dis-empowering characteristics, i.e. limitations to include ‘other’ locals, neighbourhoods and topics. We illustrate how the current self-organization, unintentionally, fuels the decreasing diversity in content by a natural selection process of a rather homogeneous group of participants. In addition, the conviction of what constitutes a successful online community is discussed for emphasizing individual empowerment and attracting empowered locals instead of vulnerable ones

    Hypothalamic‐specific proopiomelanocortin deficiency reduces alcohol drinking in male and female mice

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136536/1/gbb12362_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136536/2/gbb12362.pd

    Collective Empowerment through Local Memory Websites : balancing between group interest and common good

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    The research in this dissertation explores the social significance of local memory websites. Local memory websites offer local residents a platform where they collect and share memories about particular places or experiences in their neighbourhoods and districts. Following a systematic review and a broad field study, a narrative approach is developed to study collective levels of empowerment within the ‘Memory of East’ and the ‘Memory of West’, both in Amsterdam. Two empirical questions steer a double case study: 1) ‘How does the organizational development influence the online dynamics?’ and 2) ‘What collective empowerment do the online dynamics express?’ With its stronger social capital, the Memory of East is more likely to resist official memory intuitions, commercial popular culture and local politics than the Memory of West. On the other hand, with its more inclusive character, the Memory of West is more representative for the broad cultural backgrounds of its inhabitants than the Memory of East. These findings are shown to be related to five organizational continuums on which both websites are plotted to indicate their crucial organizational differences. Apart from a claim about the theoretical value of this model, it is illustrated how it functions as a discursive tool for the core groups behind both websites

    Semisynthetic Neoclerodanes as Kappa Opioid Receptor Probes

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    Modification of the furan ring of salvinorin A (1), the main active component of Salvia divinorum, has resulted in novel neoclerodane diterpenes with opioid receptor affinity and activity. Conversion of the furan ring to an aldehyde at the C-12 position (5) has allowed for the synthesis of analogues with new carbon-carbon bonds at that position. Previous methods for forming these bonds, such as Grignard and Stille conditions, have met with limited success. We report a palladium catalyzed Liebeskind-Srogl cross-coupling reaction of a thioester and a boronic acid that occurs at neutral pH and ambient temperature to produce ketone analogs at C-12. To the best of our knowledge, this is the first reported usage of the Liebeskind-Srogl reaction to diversify a natural product scaffold. We also describe a one-step protocol for the conversion of 1 to 12-epi-1 (3) through microwave irradiation. Previously, this synthetically challenging process has required multiple steps. Additionally, we report in this study that alkene 9 and aromatic analogues 12, 19, 23, 25, and 26 were discovered to retain affinity and selectivity at kappa opioid receptors (KOP). Finally, we report that the furan-2-yl analog of 1 (31) has similar affinity to 1. Collectively, these findings suggest that different aromatic groups appended directly to the decalin core may be well tolerated by KOP receptors, and may generate further ligands with affinity and activity at KOP receptors

    LC-MS/MS quantification of salvinorin A from biological fluids

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    A facile method for quantifying the concentration of the powerful and widely available hallucinogen salvinorin A (a selective kappa opioid agonist) from non-human primate cerebrospinal fluid (CSF) and human plasma has been developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization (ESI) mode. With CSF solid phase extraction can be avoided completely by simply diluting each sample to 10 % (v/v) acetonitrile, 1 % (v/v) formic acid and injecting under high aqueous conditions for analyte focusing. Extensive plasma sample preparation was investigated including protein precipitation, SPE column selection, and plasma particulate removal. Human plasma samples were centrifuged at 21,000 × gravity for 4 minutes to obtain clear particulate-free plasma, from which 300 ÎŒl was spiked with internal standard and loaded onto a C18 SPE column with a 100 mg mL−1 loading capacity. Guard columns (C18, hand packed 1 mm × 20 mm) were exchanged after backpressure increased above 4600psi, about 250 injections. A shallow acetonitrile/water gradient was used, 29 to 33% CH3CN over 8 minutes to elute salvinorin A. Reduction of chemical noise was achieved using tandem mass spectrometry with multiple reaction monitoring while sensitivity increases were observed using a 50 ÎŒL injection volume onto a small bore analytical column (C18, 1 mm ID × 50 mm) thus increasing peak concentration. Limits of quantification were found to be 0.0125 ng mL−1 (CSF) and 0.05 ng mL−1 (plasma) with interday precision and accuracy below 1.7 % and 9.42 % (CSF) and 3.47 % and 12.37 % (plasma) respectively. This method was used to determine the concentration of salvinorin A from an in vivo Rhesus monkey study and a trial of healthy human research participants, using behaviorally active doses
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