5,628 research outputs found
Liquid crystal anchoring transitions on aligning substrates processed by plasma beam
We observe a sequence of the anchoring transitions in nematic liquid crystals
(NLC) sandwiched between the hydrophobic polyimide substrates treated with the
plasma beam. There is a pronounced continuous transition from homeotropic to
low tilted (nearly planar) alignment with the easy axis parallel to the
incidence plane of the plasma beam (the zenithal transition) that takes place
as the exposure dose increases. In NLC with positive dielectric anisotropy, a
further increase in the exposure dose results in in-plane reorientation of the
easy axis by 90 degrees (the azimuthal transition). This transition occurs
through the two-fold degenerated alignment characteristic for the second order
anchoring transitions. In contrast to critical behavior of anchoring, the
contact angle of NLC and water on the treated substrates monotonically declines
with the exposure dose. It follows that the surface concentration of
hydrophobic chains decreases continuously. The anchoring transitions under
consideration are qualitatively interpreted by using a simple phenomenological
model of competing easy axes which is studied by analyzing anchoring diagrams
of the generalized polar and non-polar anchoring models.Comment: revtex4, 18 pages, 10 figure
Virtual porous materials to predict the air void topology and hydraulic conductivity of asphalt roads
This paper investigates the effects of air void topology on hydraulic conductivity in asphalt mixtures with porosity in the range 14%â31%. Virtual asphalt pore networks were generated using the Intersected Stacked Air voids (ISA) method, with its parameters being automatically adjusted by the means of a differential evolution optimisation algorithm, and then 3D printed using transparent resin. Permeability tests were conducted on the resin samples to understand the effects of pore topology on hydraulic conductivity. Moreover, the pore networks generated virtually were compared to real asphalt pore networks captured via X-ray Computed Tomography (CT) scans. The optimised ISA method was able to generate realistic 3D pore networks corresponding to those seen in asphalt mixtures in term of visual, topological, statistical and air void shape properties. It was found that, in the range of porous asphalt materials investigated in this research, the high dispersion in hydraulic conductivity at constant air void content is a function of the average air void diameter. Finally, the relationship between average void diameter and the maximum aggregate size and gradation in porous asphalt materials was investigated
Preprints and scholarly communication : an exploratory qualitative study of adoption, practices, drivers and barriers
Background: Since 2013, there has been a dramatic increase in the number of preprint servers. Little is known about the position of researchers, funders, research performing organisations and other stakeholders with respect to this fast-paced landscape. In this article, we explore the perceived benefits and challenges of preprint posting, alongside issues including infrastructure and financial sustainability. We also discuss the definition of a âpreprintâ in different communities, and the impact this has on uptake.
Methods: This study is based on 38 semi-structured interviews of key stakeholders, based on a purposive heterogeneous sampling approach and undertaken between October 2018 and January 2019. Interviewees were primarily drawn from biology, chemistry and psychology, where use of preprints is growing. Interviews were recorded, transcribed and subjected to thematic analysis to identify trends. Interview questions were designed based on Innovation Diffusion Theory, which was also used to interpret our results.
Results: Participants were conscious of the rising prominence of preprints and cited early and fast dissemination as their most appealing feature. Preprints were also considered to enable broader access to scientific literature and increased opportunities for informal commenting. The main concerns related to the lack of quality assurance and the âIngelfinger ruleâ. We identified trust as an essential factor in preprint posting, and highlight the enabling role of Twitter in showcasing preprints.
Conclusions: The preprints landscape is evolving fast, and disciplinary communities are at different stages in the innovation diffusion process. The landscape is characterised by experimentation, which leads to the conclusion that a one-size-fits-all approach to preprints is not feasible. Cooperation and active engagement between the stakeholders involved will play an important role going forward. We share questions for the further development of the preprints landscape, with the most important being whether preprint posting will develop as a publisher- or researcher-centric practice
âPlans for the Removal of Architectural Barriers (PEBAs) from a UD Perspective. An Interdisciplinary Process in the Italian Region Friuli Venezia Giuliaâ
It is more than thirty years since the Italian Law introduced the Plans for the Removal of Architectural Barriers (PEBAs). However, their implementation by municipalities is still limited, and accessibility is often understood as the result of the elimination of single physical obstacles, rather than the development of interconnected systems of urban spaces and collective equipment that are usable and inclusive according to Universal Design (UD) criteria. Since 2018, the Italian Friuli Venezia Giulia Autonomous Region has started a collaboration with the Universities of Trieste and Udine, in order to bring UD at the core of the implementation of the Regional Law no. 10/2018. This Law introduced significant innovations: the disposal of regional funds to support local administrations when drafting PEBAs; the delivery of a software application to facilitate the drawing of these plans; the establishment of a reference center in charge of training, information and consultancy activities on accessibility at a regional level (CRIBA); the delivery of a regional observatory for mapping and continuous monitoring of accessibility conditions and the implementation of PEBAs. The paper presents: i) an overview of the interdisciplinary work carried out by the Universities with the Region and CRIBA; ii) a focus on Universitiesâ research activities and the current state of the collaboration process; iii) reflections on further research and its operational outcomes
Parametric analysis of energy harvesting pavements operated by air convection
In this paper, an energy harvesting pavement prototype using air as the operating fluid is described and analysed. The prototype harvests the thermal energy available in the pavement through pipes embedded in its structure, where air flows thanks to natural convection. The air is able to exit the system through an updraft chimney. A parametric analysis of the controllable parameters of interest is performed in this work in order to evaluate the variation in the performance of the energy harvesting prototype in different experimental setups.
This study shows that there exists a maximum value for the air speed in each configuration and that the energy harvesting efficiency depends on the height and the diameter of the chimney. Moreover, there is a minimum value of the chimney diameter that does not allow air movement and makes the whole system behave as if no pipes were embedded in the pavement structure
Towards a competitive and sustainable OA market in Europe - A study of the open access market and policy environment
Deliverable 5.3 of OpenAIRE WP5: FP7 Post Grant Gold Open Access Pilot.
This deliverable consists of a study and an annex - and it will be supplemented by a roadmap in May 2017.
This study considers the economic factors contributing to the current state of the open-access publishing market, and evaluates the potential for European policymakers to enhance market competition and sustainability in parallel to increasing access. It was commissioned within the scope of the OpenAIRE FP7 Post-Grant Open Access Pilot, and it will be accompanied by a Roadmap document developed with inputs from an expert workshop to be held in The Hague on 20 April 2017. In accordance with the project brief, the study aims to:
Explore the current status of the OA publishing market
Analyse existing OA publishing business models
Evaluate how different national and international policies are complementing each other as a means to achieve a transition to OA
Evaluate the impact of the Framework Programme 7 Post-grant OA pilot and its implications for future similar initiatives and the transition to OA.
Provide a roadmap leading to a sustainable and competitive market
The transition to open access concerns all kinds of academic research outputs, including monographs, journal articles, and data. This study focuses on open access to peer-reviewed research articles, which constitute the bulk of the market and the primary mechanism through which research is disseminated across disciplinary communities and beyond.
This report is supplemented by an Annex containing a mid-term evaluation of the FP7 Post-Grant Open Access Pilot.This report will be accompanied by a Roadmap document developed with inputs from an expert workshop to be held in The Hague on 20 April 201
A Picture is Worth a Thousand Words: Consumer Perceptions of Agricultural Images
Individuals interpret agricultural images differently according to the direct or cultural meanings they associate with the image, as well as the perspective through which they view the image. In addition, perceptions of agricultural images are commonly influenced by stereotypes. As agricultural communicators, it is important to understand the perceptions consumers have about agricultural images. Understanding these perceptions can allow communicators to use images in their communication that will promote favorable perceptions of the industry. To better understand consumersâ perceptions of agricultural images, this study asked consumers about their perceptions using focus group methodology. Four focus groups were completed with a total of 36 participants. The results indicated that elements of semiotics and perception theory were evident in the participantsâ discussion. Thus, these theories combined with the results provide valuable information in regard to selecting images for communication that will create favorable responses among consumers
Eye See Eye Learn The Benefit of Comprehensive Eye Examinations for Preschoolers
Objective: Undetected vision problems in children can lead to permanent vision loss, a condition known as amblyopia. Early detection and treatment of the causes of amblyopia may prevent this vision loss. The objective of this paper is to look for evidence that comprehensive eye examinations upon entry to junior Kindergarten are an effective way to identify and treat vision problems early.
methods: Relevant peer-reviewed publications on amblyopia and the importance of comprehensive eye examinations were reviewed. Specific areas investigated include: the prevalence and causes of amblyopia; impact of vision problems on child development and education; impact of amblyopia and/or strabismus on quality of life; and the cost effectiveness of treating amblyopia. The validity of vision screening compared to a comprehensive eye examination was also reviewed.
Synthesis:The review suggests that without a complete eye examination many eye or vision problems remain undetected at school entry. Left uncorrected these problems negatively impact child development, education and quality of life. Reduced vision due to amblyopia also restricts future employment opportunities and increases the risk of bilateral visual impairment in adulthood. Examination procedures with high sensitivity and specificity are required to accurately detect these problems. Studies show that amblyopia treatment initiated at an early age is one of the most cost-effective of all health interventions.
Conclusion: There is good evidence in the literature that a full eye examination is critical to detect all cases of amblyopia. This and other visual problems can be detected and managed at an early age, which leads to better visual quality of life and economical outcomes. The Eye See Eye Learn program offers the âgold standardâ of eye care
A New Configuration of Vertical Axis Wind Turbine: Towards the Development of a highly distributed and efficient Wind Power Generation
Preliminary results obtained for a new configuration lift based vertical-axis wind turbine are shown. The turbine rotor is a cross flow fan type made with high curvature aerodynamic profiles. A reduced scale model of the turbine rotor has been designed and preliminary tested at the Department of Aerospace Engineering of the University of Pisa (rotor diameter 250 mm, rotor height 210 mm). The reduced scale model shows an efficiency of about eighteen per cent. The rotor is of a self-starting type. Two-dimensional CFD analyses have been performed applying both the Moving Reference Frame and the Moving Mesh conditions to the grid which surrounds the rotor blades (FluentÂź Rel. 6.3 and STAR-CCM+Âź Rel. 6.04 have been used). Noticeable scale effects have been found numerically, so, the efficiency of a full scale lift based vertical axis multi-blades optimized wind turbine is expected to be comparable with lift based horizontal-axis wind turbines
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