870 research outputs found

    Solvent effects on Grubbs’ pre-catalyst initiation rates

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    Initiation rates for Grubbs and Grubbs-Hoveyda second generation pre-catalysts have been measured accurately in a range of solvents. Solvatochromic fitting reveals different dependencies on key solvent parameters for the two pre-catalysts, consistent with different mechanisms by which the Grubbs and Grubbs-Hoveyda pre-catalysts initiate

    Wideband THz time domain spectroscopy based on optical rectification and electro-optic sampling

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    We present an analytical model describing the full electromagnetic propagation in a THz time-domain spectroscopy (THz-TDS) system, from the THz pulses via Optical Rectification to the detection via Electro Optic-Sampling. While several investigations deal singularly with the many elements that constitute a THz-TDS, in our work we pay particular attention to the modelling of the time-frequency behaviour of all the stages which compose the experimental set-up. Therefore, our model considers the following main aspects: (i) pump beam focusing into the generation crystal; (ii) phase-matching inside both the generation and detection crystals; (iii) chromatic dispersion and absorption inside the crystals; (iv) Fabry-Perot effect; (v) diffraction outside, i.e. along the propagation, (vi) focalization and overlapping between THz and probe beams, (vii) electro-optic sampling. In order to validate our model, we report on the comparison between the simulations and the experimental data obtained from the same set-up, showing their good agreement

    Street-level netocracy: rules, discretion and professionalism in a network-based intervention

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    Purpose: The paper aims to analyse the meaning and extension of discretionary power of social service professionals within network-based interventions. Design/methodology/approach: Empirically, the paper is based on a case study of a network-based policy involving private and public organisations in the Northeast of Italy (Province of Trento). Findings: The paper identifies netocracy as a social policy logic distinct from bureaucracy and professionalism. What legitimises netocracy is neither authority nor expertise but cooperation, the activation of connections and involvement, considered "good" per se. In this framework, professionalism and discretion acquire new and problematic meanings compared to street-level bureaucracy processes. Research limitations/implications: Based on a case study, the research results cannot be generalised but pave the way to further comparative investigations. Practical implications: The paper reveals that the position of professionals in netocracy is to some extent trickier than that in a bureaucracy because netocracy seems to have the power to encapsulate them and make it less likely for them to deviate from expected courses of action. Originality/value: Combining different literature streams - street level bureaucracy, professionalism, network organisations and welfare governance - and building on an original case study, the paper contribute to understanding professionalism in welfare contexts increasingly characterised by the combination of bureaucratic, professional and network logics

    Collaborative Spaces: Nodes Within an Accelerated World

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    This study investigates the locational patterns and socioeconomic implications of collaborative spaces (CSs) within the Veneto region of Italy from an accelerationist perspective. Through a comprehensive analysis of the CSs distribution, infrastructural correlations, and socioeconomic contexts, this study explores the evolving role of CSs in contemporary urban landscapes. The findings reveal a nuanced picture of CSs localisation, indicating a dispersal pattern across medium- and small-sized cities, rather than concentrating solely on major urban centres. Proximity to productive and reproductive infrastructures has emerged as a consistent theme, underscoring the economic orientation of CSs within local economic systems. Furthermore, this study delves into the ambivalence of CSs, illustrating their dual role as catalysts of knowledge-based capitalism and sites of socioeconomic tensions. Despite their initial intention to foster professional communities, CSs often become enmeshed in the broader processes of economic exploitation and hegemony. By framing CSs within the context of local innovation systems, this study highlights their potential for intensifying knowledge circulation and collaboration among local actors. This study opens avenues for future research into the evolving role of CSs within innovation systems and their broader socioeconomic implications

    Feasibility of Ultra-short Term Complexity Analysis of Heart Rate Variability in Resting State and During Orthostatic Stress

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    In this work, we study ultra-short term (UST) complexity of Heart Rate Variability (HRV) and its agreement with analysis of standard short-term (ST) HRV recordings obtained at rest and during orthostatic stress. Conditional Entropy (CE) measures have been computed using both a linear Gaussian approximation and a more accurate model-free approach based on nearest neighbors. The agreement between UST and ST indices has been compared via statistical tests and correlation analysis, suggesting the feasibility of exploiting faster algorithms and shorter time series for detecting changes in cardiovascular control during various states

    Deregulation of miRNAs in malignant pleural mesothelioma is associated with prognosis and suggests an alteration of cell metabolism

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    Malignant pleural mesothelioma (MPM) is an aggressive human cancer and miRNAs can play a key-role for this disease. In order to broaden the knowledge in this field, the miRNA expression was investigated in a large series of MPM to discover new pathways helpful in diagnosis, prognosis and therapy. We employed nanoString nCounter system for miRNA profiling on 105 MPM samples and 10 healthy pleura. The analysis was followed by the validation of the most significantly deregulated miRNAs by RT-qPCR in an independent sample set. We identified 63 miRNAs deregulated in a statistically significant way. MiR-185, miR-197, and miR-299 were confirmed differentially expressed, after validation study. In addition, the results of the microarray analysis corroborated previous findings concerning miR-15b-5p, miR-126-3p, and miR-145-5p. Kaplan-Meier curves were used to explore the association between miRNA expression and overall survival (OS) and identified a 2-miRNA prognostic signature (Let-7c-5p and miR-151a-5p) related to hypoxia and energy metabolism respectively. In silico analyses with DIANA-microT-CDS highlighted 5 putative targets in common between two miRNAs. With the present work we showed that the pattern of miRNAs expression is highly deregulated in MPM and that a 2-miRNA signature can be a new useful tool for prognosis in MPM

    Input for baroreflex analysis: which blood pressure signal should be used?

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    The baroreflex (BR) is an important physiological regulatory mechanism which reacts to blood pressure perturbations with reflex changes of target variables such as the heart period (electrocardiogram derived RR interval) or the peripheral vascular resistance (PVR). Evaluation of cardiac chronotropic (RR as a target variable) and vascular resistance (target PVR) BR arms was in previous studies mainly based on the use of the spontaneous variability of the systolic or diastolic blood pressure (SBP, DBP), respectively, as the input signals. The use of other blood pressure measures such as the mean blood pressure (MBP) as an input signal for BR analysis is still under investigation. Making the assumption that the strength of coupling along the BR indicates the more appropriate input signal for baroreflex analysis, we employ partial spectral decomposition to assess in the frequency domain the causal coupling from SBP, MBP or DBP to RR or PVR. Noninvasive beat-to-beat recording of RR, SBP, MBP and DBP and PVR was performed in 39 and 36 volunteers in whom orthostatic and cognitive loads were evoked respectively through head-up tilt and mental arithmetic task. At rest, the MBP was most tightly coupled with RR, in contrast to the analysis of the vascular resistance BR arm where the results showed similar importance of all blood pressure input signals. During orthostasis, the increased importance of SBP as the input signal for BR analysis along the cardiac chronotropic arm was demonstrated. In addition, the gain from MBP to RR was more sensitive to physiological state changes compared to gains with SBP or DBP signal as inputs. We conclude that the coupling strength depends not only on the analysed baroreflex arm but also on the selection of the input blood pressure signal and the physiological state. The MBP signal should be more frequently used for the cardiac baroreflex analysis

    A review of source tracking techniques for fine sediment within a catchment

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    Excessive transport of fine sediment, and its associated pollutants, can cause detrimental impacts in aquatic environments. It is therefore important to perform accurate sediment source apportionment to identify hot spots of soil erosion. Various tracers have been adopted, often in combination, to identify sediment source type and its spatial origin; these include fallout radionuclides, geochemical tracers, mineral magnetic properties and bulk and compound-specific stable isotopes. In this review, the applicability of these techniques to particular settings and their advantages and limitations are reviewed. By synthesizing existing approaches, that make use of multiple tracers in combination with measured changes of channel geomorphological attributes, an integrated analysis of tracer profiles in deposited sediments in lakes and reservoirs can be made. Through a multi-scale approach for fine sediment tracking, temporal changes in soil erosion and sediment load can be reconstructed and the consequences of changing catchment practices evaluated. We recommend that long-term, as well as short-term, monitoring of riverine fine sediment and corresponding surface and subsurface sources at nested sites within a catchment are essential. Such monitoring will inform the development and validation of models for predicting dynamics of fine sediment transport as a function of hydro-climatic and geomorphological controls. We highlight that the need for monitoring is particularly important for hilly catchments with complex and changing land use. We recommend that research should be prioritized for sloping farmland-dominated catchments
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