215 research outputs found

    Optical waveguide manipulation of micro- and nano-spheres

    No full text
    Optical tweezers are well-established as a tool for non-contact, non-destructive handling of biological materials [1] and of inorganic nanospheres attached to biological molecules [2]. Recently, interest has grown in optical manipulation at surfaces [3] potentially as part of the toolbox of the "lab-on-a-chip". In particular, advances have been made in trapping and propulsion of metallic and dielectric micro- and nano-particles in the evanescent fields of optical waveguides [4,5], which may form part of a planar microsystem into which optical detection and spectroscopy of separated species could also be integrated. Optical waveguides embedded in surfaces represent a powerful means of controlling the distribution of optical intensity and intensity gradient at such surfaces, for particle control. In this paper, the design of optical waveguides and waveguide devices for trapping, propulsion and sorting of gold nanospheres and latex microspheres [6,7] will be described and recent experimental results presented and compared with theoretical models. The implications of these results for some proposed applications in the biosciences will be discussed

    Experimental and computational studies of water drops falling through model oil with surfactant and subjected to an electric field

    Full text link
    The behaviour of a single sub-millimetre-size water drop falling through a viscous oil while subjected to an electric field is of fundamental importance to industrial applications such as crude oil electrocoalescers. Detailed studies, both experimental and computational, have been performed previously, but an often challenging issue has been the characterization of the fluids. As numerous authors have noted, it is very difficult to have a perfectly clean water-oil system even for very pure model oils, and the presence of trace chemicals may significantly alter the interface behaviour. In this work, we consider a well- characterized water-oil system where controlled amounts of a surface active agent (Span 80) have been added to the oil. This addition dominates any trace contaminants in the oil, such that the interface behaviour can also be well-characterized. We present the results of experiments and corresponding two-phase- flow simulations of a falling water drop covered in surfactant and subjected to a monopolar square voltage pulse. The results are compared and good agreement is found for surfactant concentrations below the critical micelle concentration.Comment: 7 pages, 9 figures, to be presented at the ICDL 2014 conferenc

    Perceptions of Selves: Beyond the Skin Bag - Analyzing self-representation and ethos in creative digital artefacts

    Get PDF
    As technological innovations reach new heights, questions regarding how we act, see, and live with machines reveal themselves. What was once viewed as mere tools have become something we perceive as part of our social world. Technological actants now hold the power of persuasion, the power to be perceived as a self. This constitutes new perspectives regarding how we relate to those with self-representational qualities. Relations between actants in social settings boil down to discourse, where this study manifests itself. The point of entry is, paradoxically, taking root in ancient theories of rhetoric. Because self-representation in digital artefacts must necessarily be produced, it becomes a text with the potential for analysis. In its broadest possible meaning, text is a modal manifestation of existence, a textual manifestation of self. The representations are always mediated, and that mediation opens up questions about authenticity, agency, and ethos. The artefacts I propose in this thesis exist in a way that changes shape in the perception of those who perceive it. When artefacts are imbued with some form of life, uniqueness, personality and ethos, approaches and attentions must change. That is dependent on the relations we allow and instil in them. We now have different relations than before, which means that the concept of ethos must be seen anew. This thesis is a philosophical and rhetorical exploration of how ethos and self-representation can be renewed to encompass more ways of being. Through perspectives inspired by Posthumanism and Actor-Network Theory, I explore themes relating to self-representation and ethos to conceptualize an updated framework that, in essence, “de-anthropocentrize” our field of view. This thesis does not aim to be either final or limiting, but a starting point in opening a conversation about the rhetorical impact we encounter every day through humans and otherwise.Mastergradsoppgave i digital kulturDIKULT350MAHF-DIKU

    Information- and Material Flows in Warehouse Management: A Case Study

    Get PDF

    Electronic exchange of discharge summaries between hospital and municipal care from health personnel's perspectives

    Get PDF
    <p><strong>Introduction</strong>: Information and communication technologies (ICT) are seen as potentially powerful tools that may promote integration of care across organisational boundaries. Here we present findings from a study of a Norwegian project where an electronic interdisciplinary discharge summary was implemented to improve communication and information exchange between the municipal care service and the associated hospital.<br /><strong>Objective</strong>: To investigate the implications of introduction and use of the electronic discharge summary for health staff, and relate it to the potential for promoting integration of care across the hospital-municipality boundary. <br /><strong>Methods</strong>: We conducted semi-structured interviews with 49 health care providers. The material was analysed using a three-step process to identify the main themes and categories. <br /><strong>Findings</strong>: The study showed that the electronic discharge summary contributed to changes in health staff's work processes as well as increased legibility of summaries, and enabled municipal care staff to be better prepared for receiving patients, even though the information content mostly remained unaltered and was not always accurate.<br /><strong>Conclusion</strong>: Introduction of electronic discharge summaries did not result in a significant increase in integration of care. However, the project was a catalyst for the collaborating participants to address their interaction from new perspectives.</p

    Cultural diversity between hospital and community nurses: implications for continuity of care

    Get PDF
    Introduction: Health care systems and nurses need to take into account the increasing number of people who need post-hospital nursing care in their homes. Nurses have taken a pivotal role in discharge planning for frail patients. Despite considerable effort and focus on how to undertake hospital discharge successfully, the problem of ensuring continuity of care remains. <br /><br />Challenges: In this paper, we highlight and discuss three challenges that seem to be insufficiently articulated when hospital and community nurses interact during discharge planning. These three challenges are: how local practices circumvent formal structures, how nurses' different perspectives influence their assessment of patients' need for post-hospital care, and how nurses have different understanding of what it means to be ‘ready to be discharged’. <br /><br />Discussion: We propose that nurses need to discuss these challenges and their implications for nursing care so as to be ready to face changing demands for health care in future

    Influence of surfactants on the electrohydrodynamic stretching of water drops in oil

    Full text link
    In this paper we present experimental and numerical studies of the electrohydrodynamic stretching of a sub-millimetre-sized salt water drop, immersed in oil with added non-ionic surfactant, and subjected to a suddenly applied electric field of magnitude approaching 1 kV/mm. By varying the drop size, electric field strength and surfactant concentration we cover the whole range of electric capillary numbers (CaECa_E) from 0 up to the limit of drop disintegration. The results are compared with the analytical result by Taylor (1964) which predicts the asymptotic deformation as a function of CaECa_E. We find that the addition of surfactant damps the transient oscillations and that the drops may be stretched slightly beyond the stability limit found by Taylor. We proceed to study the damping of the oscillations, and show that increasing the surfactant concentration has a dual effect of first increasing the damping at low concentrations, and then increasing the asymptotic deformation at higher concentrations. We explain this by comparing the Marangoni forces and the interfacial tension as the drops deform. Finally, we have observed in the experiments a significant hysteresis effect when drops in oil with large concentration of surfactant are subjected to repeated deformations with increasing electric field strengths. This effect is not attributable to the flow nor the interfacial surfactant transport

    Metasurface supporting quasi-BIC for optical trapping and Raman-spectroscopy of biological nanoparticles

    Get PDF
    Optical trapping combined with Raman spectroscopy have opened new possibilities for analyzing biological nanoparticles. Conventional optical tweezers have proven successful for trapping of a single or a few particles. However, the method is slow and cannot be used for the smallest particles. Thus, it is not adapted to analyze a large number of nanoparticles, which is necessary to get statistically valid data. Here, we propose quasi-bound states in the continuum (quasi-BICs) in a silicon nitride (Si3N4) metasurface to trap smaller particles and many simultaneously. The quasi-BIC metasurface contains multiple zones with high field-enhancement (‘hotspots’) at a wavelength of 785 nm, where a single nanoparticle can be trapped at each hotspot. We numerically investigate the optical trapping of a type of biological nanoparticles, namely extracellular vesicles (EVs), and study how their presence influences the resonance behavior of the quasi-BIC. It is found that perturbation theory and a semi-analytical expression give good estimates for the resonance wavelength and minimum of the potential well, as a function of the particle radius. This wavelength is slightly shifted relative to the resonance of the metasurface without trapped particles. The simulations show that the Q-factor can be increased by using a thin metasurface. The thickness of the layer and the asymmetry of the unit cell can thus be used to get a high Q-factor. Our findings show the tight fabrication tolerances necessary to make the metasurface. If these can be overcome, the proposed metasurface can be used for a lab-on-a-chip for mass-analysis of biological nanoparticles

    Nurses’ information management at patients’ discharge from hospital to home care

    Get PDF
    PURPOSE: The purpose of this paper is to explore and compare hospital and home care nurses’ assessment of their information management at patients’ discharge from hospital to home care before and after the hospital implemented an electronic nursing discharge note. THEORY: This paper draws on the concept of inter-organizational continuity of care, and specifically addresses the contribution of the implementation of an electronic patient record (EPR). METHODS: The study has a prospective descriptive design. A questionnaire addressing the information that hospital and home care nurses exchange when patients need continuing care after hospitalization was developed and used. RESULTS: Hospital and home care nurses differed in the way they assessed the structures and content of the information they exchanged, both before and after the EPR implementation. CONCLUSION AND DISCUSSION: There is a need to take account of the different organizational contexts within which the two nursing groups work. The organizational context (hospital versus home care) has implications for the nurses’ assessment of the information they exchange. In further development of EPR, it is therefore essential to clarify the context-related information needs of the various health care provider groups as part of the commitment to patient safety
    • …
    corecore