145 research outputs found

    Genetic and hormonal control of vascular tissue proliferation

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    The plant vascular system develops from a handful of provascular initial cells in the early embryo into a whole range of different cell types in the mature plant. In order to account for such proliferation and to generate this kind of diversity, vascular tissue development relies on a large number of highly oriented cell divisions. Different hormonal and genetic pathways have been implicated in this process and several of these have been recently interconnected. Nevertheless, how such networks control the actual division plane orientation and how they interact with the generic cell cycle machinery to coordinate these divisions remains a major unanswered question

    Phenomenology for Introductory Architectural Analysis Courses: The pentagon methodological approach

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    As a consequence of fruitful discussions about joining theory and practice both in design research and educational design programmes, this article aims to explore phenomenological parameters in the framework of an exercise for Engineer-architecture students from the University of Leuven in Belgium. Relying upon the arguments of recognised architects regarding the importance of the phenomenological approach in the field of architecture, it is intended to propose a five-step method (pentagon) to add to architectural analytical exercises. The paper argues that an explicit phenomenological awareness within architectural design education should be addressed in addition to the potential references to architectural phenomenology in theoretical courses or in the discourse of architectural design teachers during the studio courses. This article begins this process through the discussion of one example: ‘Integrated Seminar on Housing’ which is taught in the first semester of the bachelor programme. A qualitative review of theoutcomes of the exercise stresses a positive effect in the development of students’ skills that are not an explicit focus of methodologies related to programmatic or technical skills. The conclusions encourage the development of the experimental study to improve the complementarity of the phenomenological approach with the more technical methodologies. In the final reflectionsabout the results of the pentagon methodological approach some evidence is provided in respect to the article’s claims

    Lanthanide-assisted deposition of strongly electro-optic PZT thin films on silicon: toward integrated active nanophotonic devices

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    The electro-optical properties of lead zirconate titanate (PZT) thin films depend strongly on the quality and crystallographic orientation of the thin films. We demonstrate a novel method to grow highly textured PZT thin films on silicon using the chemical solution deposition (CSD) process. We report the use of ultrathin (5–15 nm) lanthanide (La, Pr, Nd, Sm) based intermediate layers for obtaining preferentially (100) oriented PZT thin films. X-ray diffraction measurements indicate preferentially oriented intermediate Ln2O2CO3 layers providing an excellent lattice match with the PZT thin films grown on top. The XRD and scanning electron microscopy measurements reveal that the annealed layers are dense, uniform, crack-free and highly oriented (>99.8%) without apparent defects or secondary phases. The EDX and HRTEM characterization confirm that the template layers act as an efficient diffusion barrier and form a sharp interface between the substrate and the PZT. The electrical measurements indicate a dielectric constant of ∼650, low dielectric loss of ∼0.02, coercive field of 70 kV/cm, remnant polarization of 25 μC/cm2, and large breakdown electric field of 1000 kV/cm. Finally, the effective electro-optic coefficients of the films are estimated with a spectroscopic ellipsometer measurement, considering the electric field induced variations in the phase reflectance ratio. The electro-optic measurements reveal excellent linear effective pockels coefficients of 110 to 240 pm/V, which makes the CSD deposited PZT thin film an ideal candidate for Si-based active integrated nanophotonic devices

    Archeologisch vooronderzoek Lijnmolenstraat (Gent)

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    Dit rapport werd ingediend bij het agentschap samen met een aantal afzonderlijke digitale bijlagen. Een aantal van deze bijlagen zijn niet inbegrepen in dit pdf document en zijn niet online beschikbaar. Sommige bijlagen (grondplannen, fotos, spoorbeschrijvingen, enz.) kunnen van belang zijn voor een betere lezing en interpretatie van dit rapport. Indien u deze bijlagen wenst te raadplegen kan u daarvoor contact opnemen met: [email protected]

    Peroneal nerve: normal anatomy and pathologic findings on routine MRI of the knee

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    Background : Peroneal nerve lesions are not common and are often exclusively assessed clinically and electromyographically. Methods : On a routine MR examination without dedicated MR-neurography sequences the peroneal nerve can readily be assessed. Axial T1-weighted sequences are especially helpful as they allow a good differentiation between the nerve and the surrounding fat. Results : The purpose of this article is to review the normal anatomy and pathologic conditions of the peroneal nerve around the knee. Conclusion : In the first part the variable anatomy of the peroneal nerve around the knee will be emphasized, followed by a discussion of the clinical findings of peroneal neuropathy and general MR signs of denervation. Six anatomical features may predispose to peroneal neuropathy: paucity of epineural tissue, biceps femoris tunnel, bifurcation level, superficial course around the fibula, fibular tunnel and finally the additional nerve branches. In the second part we discuss the different pathologic conditions: accidental and surgical trauma, and intraneural and extraneural compressive lesions. Teaching Points : • Six anatomical features contribute to the vulnerability of the peroneal nerve around the knee. • MR signs of muscle denervation within the anterior compartment are important secondary signs for evaluation of the peroneal nerve. • The most common lesions of the peroneal nerve are traumatic or compressive. • Intraneural ganglia originate from the proximal tibiofibular joint. • Axial T1-weighted images are the best sequence to visualise the peroneal nerve on routine MRI

    Colour Appearance Modelling for Self-luminous Colours

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    An experimental setup and procedure for the evaluation of self- luminous colours viewed against both dark and luminous backgrounds is presented. Physical and visual data of self-luminous colours is gathered in order to develop a Colour Appearance Model for self-luminous colours under different viewing conditions. This model is needed for the evaluation of light sources. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

    The delegated authority model misused as a strategy of disengagement in the case of climate change

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    The characterisation of anthropogenic climate change as a violation of basic human rights is gaining wide recognition. Many people believe that tackling this problem is exclusively the job of governments and supranational institutions (especially the United Nations Framework Convention on Climate Change). This argument can be traced back to the delegated authority model, according to which the legitimacy of political institutions depends on their ability to solve problems that are difficult to address at the individual level. Since the institutions created to tackle climate change fail to do so, their legitimacy is under great pressure and can only be saved by considerations of feasibility. We argue that democratically elected representatives are able to claim that a more robust climate policy is unfeasible, but only because the mandate we as citizens grant them is very restrictive. Instead of shifting responsibility for the thoroughly inadequate response to climate change fully to political representatives, we should highlight the failure of the political community as a whole to fulfil its responsibility at the input-side of the delegation of authority. When individual voters fail to fulfil the minimal obligation to at least vote for parties that explicitly advocate robust climate policies, they cannot hide behind the delegated authority argument, but should accept their complicity in the massive violations of basic human rights caused by the failure to successfully tackle climate change
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