326 research outputs found

    Nondestructive evaluation techniques for nickel-cadmium aerospace battery cells

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    The ac impedance characteristics of Ni-Cd cells as an in-situ, nondestructive means of determining cell lifetime, particularly with respect to the probability of premature failure were evaluated. Emphasis was on evaluating Ni-Cd cell impedance over a wide frequency range (10,000 to 0.0004 Hz) as the cells were subjected to charge/discharge cycle testing. The results indicate that cell degradation is reflected in the low frequency (Warburg) impedance characteristics associated with diffusion processes. The Warburg slope (W) was found to steadily increase as a function of cell aging for completely discharged cells. In addition, based on data for two cells, a high or rapidly increasing value for W signals imminent cell failure by one mechanism. Degradation by another mechanism is apparently reflected in a fall-off (roll-over) of W at lower frequencies. As a secondary result, the frequency dependence of the absolute cell impedance at low frequencies (5 - 500 mHz) was found to be a good indication of the cell state-of-charge

    Collaboration and conflict between agencies and clients

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    Public relations agencies are an important part of the public relations industry, but their relations with client organizations are rarely studied. There is more literature and studies in agency-client relations in advertising than in public relations. This paper reviews literature and reports results of an empirical study into perceptions of public relations agencies and their clients on the reasons for their cooperation and sources of conflict between them. Results show that agencies misperceive reasons for which they are hired and the sources of conflict in the relationship. The paper offers several suggestions about how to tackle the problem: notwithstanding rebranding into consultancies and firms, public relations agencies-client relations should be studied as a particular example of a broader family of agency-client relations. Also agencies should study and strategically manage relations with their clients, while being realistic about client organization’s needs – sometimes they just need additional arms and legs

    Experimental constraints on a dark matter origin for the DAMA annual modulation effect

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    A claim for evidence of dark matter interactions in the DAMA experiment has been recently reinforced. We employ a new type of germanium detector to conclusively rule out a standard isothermal galactic halo of Weakly Interacting Massive Particles (WIMPs) as the explanation for the annual modulation effect leading to the claim. Bounds are similarly imposed on a suggestion that dark pseudoscalars mightlead to the effect. We describe the sensitivity to light dark matter particles achievable with our device, in particular to Next-to-Minimal Supersymmetric Model candidates.Comment: v4: introduces recent results from arXiv:0807.3279 and arXiv:0807.2926. Sensitivity to pseudoscalars is revised in light of the first. Discussion on the subject adde

    Strategic communication across borders: Country and age effects in the practice of communication professionals in Europe

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    In this research we investigated whether the perception of the importance of certain types of media, strategic issues, and excellence in the professional field of strategic communication in Europe differs across countries and across generations. Data were used from the 2007 (N = 1087) and 2016 (N = 2710) edition of the European Communication Monitor (ECM), an annual survey among strategic communication professionals in Europe. For the first time a basic two-level multilevel regression model was used to assess country effects and individual predictors (age, gender, education, position, and experience in the field) of media use (of mass media, owned media, social media, and interpersonal communication) and perceptions of the level of excellence of communication of the organisation. Country and generational effects on the perception of strategic issues for the field were analysed using chi-square tests. Results show that in 2016 country effects are significant for the perception of the importance of mass media and social media use, interpersonal communication, and strategic issues for the field. In 2007 no such country effects were found. These results suggest that the influence and the context of the country of residence of the strategic communication professional has increased between 2007 and 2016

    Public relations and the rise of hypermodern values: Exploring the profession in Europe

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    © 2018 This article raises the question of whether European public relations (PR) and communications professionals perceive a cultural transformation in the direction of hypermodernity, and if so, attempts to assess how this influences their organizations and their work. Questions were asked in the European Communication Monitor 2017, an annual survey among communications professionals, and 3387 respondents from 50 European countries filled in the questionnaire. The results indicate that European professionals recognize a cultural transformation in the direction of hyper consumption, hyper modernization and hyper narcissism that influences the communication between their organizations and their stakeholders. A cluster analysis shows that less than half of the respondents perceive a transformation of their organization in the direction of hypermodern characteristics and values. Organizations with post/hypermodern characteristics have superior communications departments compared to modern organizations. Post/hypermodern organizations and excellent communications departments also engage more often in societal debates than other types of organizations and departments

    Neurosteroid Modulation of Synaptic and Extrasynaptic GABAA Receptors of the Mouse Nucleus Accumbens

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    The recent approval of formulations of the endogenous neurosteroid allopregnanolone (brexanolone) and the synthetic neuroactive steroid SAGE-217 (zuranolone) to treat postpartum depression (PPD) has encouraged further research to elucidate why these potent enhancers of GABAAR function are clinically effective in this condition. Dopaminergic projections from the ventral tegmental area (VTA) to the nucleus accumbens are associated with reward/motivation and brain imaging studies report that individuals with PPD show reduced activity of this pathway in response to reward and infant engagement. However, the influence of neurosteroids on GABA-ergic transmission in the nucleus accumbens has received limited attention. Here, we investigate, in the medium spiny neurons (MSNs) of the mouse nucleus accumbens core, the effect of allopregnanolone, SAGE-217 and other endogenous and synthetic steroids of interest on fast phasic and tonic inhibition mediated by synaptic (α1/2βγ2) and extrasynaptic (α4βδ) GABAARs, respectively. We present evidence suggesting the resident tonic current results from the spontaneous opening of δ-GABAARs, where the steroid-enhanced tonic current is GABA-dependent. Furthermore, we demonstrate local neurosteroid synthesis in the accumbal slice preparation and reveal that GABA-ergic neurotransmission of MSNs is influenced by an endogenous neurosteroid tone. Given the dramatic fluctuations in allopregnanolone levels during pregnancy and postpartum, this neurosteroid-mediated local fine-tuning of GABAergic transmission in the MSNs will probably be perturbed

    Results from a Search for Light-Mass Dark Matter with a P-type Point Contact Germanium Detector

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    We report on several features present in the energy spectrum from an ultra low-noise germanium detector operated at 2,100 m.w.e. By implementing a new technique able to reject surface events, a number of cosmogenic peaks can be observed for the first time. We discuss several possible causes for an irreducible excess of bulk-like events below 3 keVee, including a dark matter candidate common to the DAMA/LIBRA annual modulation effect, the hint of a signal in CDMS, and phenomenological predictions. Improved constraints are placed on a cosmological origin for the DAMA/LIBRA effect.Comment: 4 pages, 4 figures. v2: submitted version. Minimal changes in wording, one reference adde
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