63 research outputs found
Free volume in poly(propylene glycol) and its relationships to spin probe reorientation
No full textIn this work we carried out positron annihilation lifetime spectroscopy (PALS) on pure poly(propylene glycol) (PPG 4000) and an electron spin resonance (ESR) study on PPG 4000 doped with the spin probe TEMPO. The spectral and dynamic features of both the microscopic probes such as the ortho-positronium (o-Ps) lifetime, tau(3), the spectral parameter, T(50) (G), and the correlation time of spin probe, T(o), as a function of the temperature were compared. New empirical relationships between the characteristic PALS temperatures (T(b1)(L) and T(b2)(L)) and the characteristic ESR temperatures (T(X1)(L) and T(X2)(L)) have been revealed. In addition, these characteristic PALS and ESR temperatures can be connected with the Schonhals and Stickel (T(B)(SCH), T(B)(ST)) temperatures of the primary alpha relaxation process of PPG 4000 B 13 as obtained by dielectric spectroscopy (DS) studies in the literature. Next, the mean free volume hole sizes of the matrix were related to the spin probe size and to the Arrhenius or the non-Arrhenius motional regimes of TEMPO. Finally, the temperature dependences of the reorientational correlation time have been analysed using the Vogel-Fulcher-Tamman-Hesse (VFTH) equation and its generalized form, i.e., the Bendler-Shlesinger-Fontanella (BSF) one, the latter derived from the defect diffusion model of the dynamics and transport properties. The fitting parameters are then compared with those of the primary alpha relaxation process. (c) 2006 Elsevier B.V. All rights reserved
Balancing exploration and exploitation in transferring research into practice : a comparison of five knowledge translation entity archetypes
No full textBackground: Translating knowledge from research into clinical practice has emerged as a practice of increasing importance. This has led to the creation of new organizational entities designed to bridge knowledge between research and practice. Within the UK, the Collaborations for Leadership in Applied Health Research and Care (CLAHRC) have been introduced to ensure that emphasis is placed in ensuring research is more effectively translated and implemented in clinical practice. Knowledge translation (KT) can be accomplished in various ways and is affected by the structures, activities, and coordination practices of organizations. We draw on concepts in the innovation literature—namely exploration, exploitation, and ambidexterity—to examine these structures and activities as well as the ensuing tensions between research and implementation.
Methods: Using a qualitative research approach, the study was based on 106 semi-structured, in-depth interviews with the directors, theme leads and managers, key professionals involved in research and implementation in nine CLAHRCs. Data was also collected from intensive focus group workshops.
Results: In this article we develop five archetypes for organizing KT. The results show how the various CLAHRC entities work through partnerships to create explorative research and deliver exploitative implementation. The different archetypes highlight a range of structures that can achieve ambidextrous balance as they organize activity and coordinate practice on a continuum of exploration and exploitation.
Conclusion: This work suggests that KT entities aim to reach their goals through a balance between exploration and exploitation in the support of generating new research and ensuring knowledge implementation. We highlight different organizational archetypes that support various ways to maintain ambidexterity, where both exploration and exploitation are supported in an attempt to narrow the knowledge gaps. The KT entity archetypes offer insights on strategies in structuring collaboration to facilitate an effective balance of exploration and exploitation learning in the KT process
Importance of Hole Generation on Modeling and Simulation of Schottky and MESFET Structures
No full textA new compact model for the analysis of the anomalies in I-V characteristics of Schottky diodes
No full textTranscription-induced supercoiling as the driving force of chromatin loop extrusion during formation of TADs in interphase chromosomes
No full textUsing molecular dynamics simulations, we show here that growing plectonemes resulting from transcription-induced supercoiling have the ability to actively push cohesin rings along chromatin fibres. The pushing direction is such that within each topologically associating domain (TAD) cohesin rings forming handcuffs move from the source of supercoiling, constituted by RNA polymerase with associated DNA topoisomerase TOP1, towards borders of TADs, where supercoiling is released by topoisomerase TOPIIB. Cohesin handcuffs are pushed by continuous flux of supercoiling that is generated by transcription and is then progressively released by action of TOPIIB located at TADs borders. Our model explains what can be the driving force of chromatin loop extrusion and how it can be ensured that loops grow quickly and in a good direction. In addition, the supercoiling-driven loop extrusion mechanism is consistent with earlier explanations proposing why TADs flanked by convergent CTCF binding sites form more stable chromatin loops than TADs flanked by divergent CTCF binding sites. We discuss the role of supercoiling in stimulating enhancer promoter contacts and propose that transcription of eRNA sends the first wave of supercoiling that can activate mRNA transcription in a given TAD
Simulation of current transport in highly doped semiconductor structures including the tunneling effect
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Simulation of electrical parameters for Ru/Ta2O5/SiO2/Si(p) high-k MOS structure
No full textThe contribution presents the results of simulation of direct tunnelling of free charge carriers through a thin gateinsulator in MOS structures consisting of a Ta2O5/SiO2 bilayer taking into account also indirect tunnelling of free chargecarriers through the SiO2/Si interface traps. The calculated I–V and C–V curves reveal the processes of electron and holetunnelling through the insulator-to-semiconductor potential barrier that can be divided into four classes
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