620 research outputs found

    Experimental Evidence for the Incorporation of Two Metals at Equivalent Lattice Positions in Mixed-Metal Metal–Organic Frameworks

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    Metal–organic frameworks containing multiple metals distributed over crystallographically equivalent framework positions (mixed‐metal MOFs) represent an interesting class of materials, since the close vicinity of isolated metal centers often gives rise to synergistic effects. However, appropriate characterization techniques for detailed investigations of these mixed‐metal metal–organic framework materials, particularly addressing the distribution of metals within the lattice, are rarely available. The synthesis of mixed‐metal FeCuBTC materials in direct syntheses proved to be difficult and only a thorough characterization using various techniques, like powder X‐ray diffraction, X‐ray absorption spectroscopy and electron paramagnetic resonance spectroscopy, unambiguously evidenced the formation of a mixed‐metal FeCuBTC material with HKUST‐1 structure, which contained bimetallic Fe−Cu paddlewheels as well as monometallic Cu−Cu and Fe−Fe units under optimized synthesis conditions. The in‐depth characterization showed that other synthetic procedures led to impurities, which contained the majority of the applied iron and were impossible or difficult to identify using solely standard characterization techniques. Therefore, this study shows the necessity to characterize mixed‐metal MOFs extensively to unambiguously prove the incorporation of both metals at the desired positions. The controlled positioning of metal centers in mixed‐metal metal–organic framework materials and the thorough characterization thereof is particularly important to derive structure–property or structure–activity correlations

    Recognizing recurrent neural networks (rRNN): Bayesian inference for recurrent neural networks

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    Recurrent neural networks (RNNs) are widely used in computational neuroscience and machine learning applications. In an RNN, each neuron computes its output as a nonlinear function of its integrated input. While the importance of RNNs, especially as models of brain processing, is undisputed, it is also widely acknowledged that the computations in standard RNN models may be an over-simplification of what real neuronal networks compute. Here, we suggest that the RNN approach may be made both neurobiologically more plausible and computationally more powerful by its fusion with Bayesian inference techniques for nonlinear dynamical systems. In this scheme, we use an RNN as a generative model of dynamic input caused by the environment, e.g. of speech or kinematics. Given this generative RNN model, we derive Bayesian update equations that can decode its output. Critically, these updates define a 'recognizing RNN' (rRNN), in which neurons compute and exchange prediction and prediction error messages. The rRNN has several desirable features that a conventional RNN does not have, for example, fast decoding of dynamic stimuli and robustness to initial conditions and noise. Furthermore, it implements a predictive coding scheme for dynamic inputs. We suggest that the Bayesian inversion of recurrent neural networks may be useful both as a model of brain function and as a machine learning tool. We illustrate the use of the rRNN by an application to the online decoding (i.e. recognition) of human kinematics

    The Secret to Successful User Communities: An Analysis of Computer Associates’ User Groups

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    This paper provides the first large scale study that examines the impact of both individual- and group-specific factors on the benefits users obtain from their user communities. By empirically analysing 924 survey responses from individuals in 161 Computer Associates' user groups, this paper aims to identify the determinants of successful user communities. To measure success, the amount of time individual members save through having access to their user networks is used. As firms can significantly profit from successful user communities, this study proposes four key implications of the empirical results for the management of user communities

    Situating Speech: A Rhetorical Approach to Political Strategy

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    Ideas are increasingly acknowledged as factors in explaining political behaviour. But often they are treated as inert resources rather than dynamic instances of action in themselves. The latter, I propose, requires reflection on the character of speech – as the medium of ideas – in responding to and refiguring a prevailing situation. I undertake such reflection by setting out a rhetorical approach to political strategy. Building upon ‘interpretive’ advances in political science I shift the focus from stable cognitive frames to the dynamics of argumentation where ideas work expressively. I then explore the rhetorical aspect of strategising with attention to the way speech serves to orient audiences by creatively re-appropriating a situation. That approach is shown to be consistent with a ‘dialectical’ political sociology that emphasises the interaction of structure and agency. Finally, I sketch a method for undertaking rhetorical analysis and indicate how it might be applied to a concrete example

    Public Relations Rhetoric: Criticism, Dialogue, and the Long Now

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    This essay provides a response to the articles in this special issue by introducing the concepts of dialogue, groupthink, and long-term thinking. The philosophy of the Long Now Foundation (an organization devoted to sustainable development and long-term planning) is used as a frame for the essay because of its close fit with rhetoric and dialogue. The essay examines the contributions to the special issue and identifies similarities of thought and argument.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Influence of solvent granularity on the effective interaction between charged colloidal suspensions

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    We study the effect of solvent granularity on the effective force between two charged colloidal particles by computer simulations of the primitive model of strongly asymmetric electrolytes with an explicitly added hard sphere solvent. Apart from molecular oscillating forces for nearly touching colloids which arise from solvent and counterion layering, the counterions are attracted towards the colloidal surfaces by solvent depletion providing a simple statistical description of hydration. This, in turn, has an important influence on the effective forces for larger distances which are considerably reduced as compared to the prediction based on the primitive model. When these forces are repulsive, the long-distance behaviour can be described by an effective Yukawa pair potential with a solvent-renormalized charge. As a function of colloidal volume fraction and added salt concentration, this solvent-renormalized charge behaves qualitatively similar to that obtained via the Poisson-Boltzmann cell model but there are quantitative differences. For divalent counterions and nano-sized colloids, on the other hand, the hydration may lead to overscreened colloids with mutual attraction while the primitive model yields repulsive forces. All these new effects can be accounted for through a solvent-averaged primitive model (SPM) which is obtained from the full model by integrating out the solvent degrees of freedom. The SPM was used to access larger colloidal particles without simulating the solvent explicitly.Comment: 14 pages, 16 craphic

    Target and reality of adjuvant endocrine therapy in postmenopausal patients with invasive breast cancer

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    Previous research evaluating the use of adjuvant endocrine therapy among postmenopausal breast cancer patients showed with 15–50% wide ranges of non-adherence rates. We evaluated this issue by analysing an unselected study group comprising of 325 postmenopausal women, diagnosed from 1997 to 2003 with hormonal receptor-positive invasive breast cancer. The different clinical situations that led to the discontinuation of adjuvant endocrine therapy were clearly defined and differentiated: non-adherence was not simply the act of stopping medication, but rather the manifestation of an intentional behaviour of the patient. Of the 287 patients who initiated endocrine therapy, 191 (66.6%) fully completed this treatment. Thirty-one patients (10.8%) showed non-adherence to therapy. Patients who had follow-up with a general practitioner, rather than in an oncologic unit, were more likely to be non-adherent (P=0.0088). Of 25 patients who changed medication due to therapy-related adverse effects, 20 (80%) patients fully completed the therapy after drug change. In adjuvant endocrine therapy, a lowering of the non-adherence rate to 10.8%, the lowest reported in the literature, is realistic when patients are cared for by a specialised oncologic unit focusing on the individual needs of the patients

    What does security culture look like for small organizations?

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    The human component is a significant factor in information security, with a large numbers of breaches occurring due to unintentional user error. Technical solutions can only protect information so far and thus the human aspect of security has become a major focus for discussion. Therefore, it is important for organisations to create a security conscious culture. However, currently there is no established representation of security culture from which to assess how it can be manoeuvred to improve the overall information security of an organization. This is of particular importance for small organizations who lack the resources in information security and for whom the culture of the organization exerts a strong influence. A review of multiple definitions and descriptions of security culture was made to assess and analyse the drivers and influences that exist for security culture in small organizations. An initial representation of the factors that should drive security culture, together with those that should only influence it, was constructed. At a fundamental level these drivers are related to a formulated response to security issues rather than a reaction to it, and should reflect the responsibility allocated in a secure environment. In contrast, the influences on security culture can be grouped by communities of practice, individual awareness and organizational management. The encapsulation of potential driving and influencing factors couched in information security terms rather than behavioural science terms, will allow security researchers to investigate how a security culture can be fostered to improve information security in small organizations
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