Trojans of ambiguity vs resilient regeneration: visual meaning in cities

© 2020 by the author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License (https://creativecommons.org/licenses/by/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license.This paper presents a theoretical framework that helps identify visual sustainability in urban projects and evaluates its relevance for the use, design and making of public space. It is aimed at showing how the process of urban regeneration is far more nuanced and sophisticated than much of today’s building industry allows for. The first part of the article provides an outline of this framework, by drawing from the notion of ambiguity and discussing regeneration around a concept of trojans of ambiguity: by which we simply mean that modern-day regeneration projects are often a confusion of meaning. The framework is then applied to two case studies: Heygate, and Sidewalk Labs Toronto. The Heygate regeneration produced a negative emotionally charged process and social displacement. By contrast Sidewalk Labs Toronto exemplifies a technologically clean start for regeneration, on a site with little social vitality or history. The starting points for each ultimately point to two very different outcomes. Visual sustainability represents ‘the technology before the technology’ and future research must recognise how human needs, not technology, provide the meaning into ‘how’ we may create a successful, smart, and sustainable urban environment.Peer reviewe

Efficacy of Platelet Rich Plasma and Platelet Rich Fibrin in Periodontal Regeneration: Systematic Review.

Regeneration is defined as the reproduction or reconstruction of a lost part or injury of the body in such a way that the architecture and function of the lost or injured tissue are completely restored. The goal of regenerative periodontal therapy is to restore the structure and function of the periodontium. The positive effects of Platelet-rich plasma (PRP) are attributed to the angiogenic, mitogenic and proliferative capacities of growth factors such as platelet-derived growth factor, transforming growth factor and vascular endothelial growth factor. Platelet-rich fibrin (PRF) is a second generation platelet concentrate that allows fibrin membranes enriched with platelets and growth factors to be obtained after starting an anticoagulant-free blood collection without any biomechanical artificial modification. The objective of this review is to know the efficacy of platelet-rich plasma and platelet-rich fibrin in the periodontal regeneration of intrabony defects. The clinical implications for this autologous material are promising. Further long term, larger, multicentred randomized controlled clinical trials are required to determine the effects of PRP and PRF on the regeneration of alveolar bone due to periodontal disease

Auxin pretreatment promotes regeneration of sugarcane (Saccharum spp. hybrids) midrib segment explants

We have developed a new, simple, quick and genotype-independent method for direct regeneration of sugarcane using novel midrib segment explants. Our protocol involves two steps: the pretreatment of starting material on MS (Murashige and Skoog (1962) Physiol Plant 15:473–497) medium containing 3.0 mg/l 2,4- dichlorophenoxyacetic acid (2,4-D) for 8 days under continuous dark and subsequent transfer of the explants to MS medium augmented with 0.1 mg/l benzyladenine (BA) and 0.1 mg/l naphthaleneacetic acid (NAA) under light-dark conditions. On the regeneration medium, numerous globular structures appeared from the explants and subsequently differentiated into shoots. Regenerated shoots attained 2–5 cm height within 30 days of culture initiation and readily rooted on MS basal medium. Hardened plants were successfully established in the greenhouse. The regulation of sugarcane morphogenesis by auxin pretreatment is discussed

High efficiency protoplast isolation from in vitro cultures and hairy roots of Maesa lanceolata

In vitro cultures of the medicinal plant Maesa lanceolata were established to enable the cultivation of plant material for the production of protoplasts. Callus cultures were initiated using leaves collected from shoot cultures and the root tips from hairy root cultures obtained upon Agrobacterium rhizogenes transformation. For the isolation of protoplast, the different explant material of M. lanceolata was exposed to an enzyme mixture consisting of 1.5% cellulase, 0.5% macerozyme R-10 and 0.5 M mannitol. About 6 x 106 protoplasts g-1 fresh weight were obtained from leaf material and 5 x 105 protoplasts g-1 fresh weight from callus. To obtain high amounts of hairy root protoplasts, the cultures were pretreated with the auxin indole-3-butyric acid (IBA) that stimulated the formation of novel root tips. Using the dissected root tips as starting material, 8 x 105 protoplasts g-1 fresh weight were obtained per preparation. The protoplast isolation method will enable further studies on the transformation and fusion of protoplasts from M. lanceolata

Histological and immunohistochemical evaluation of mandibular bone tissue regeneration

The purpose of the study was to perform an immunohistochemical and histological evaluation of samples taken from different bone regeneration procedures in atrophic human mandible. 30 patients (15 men and 15 women, age range of 35-60 years), non-smokers, with good general and oral health were recruited in this study and divided into three groups. The first group included patients who were treated with blood Concentration Growth Factors (bCGF), the second group included patients who were treated with a mixture of bCGF and autologous bone, while the third group of patients was treated with bCGF and tricalcium phosphate/hydroxyapatite (TCP-HA). Six months after the regenerative procedures, all patients undergone implant surgery, and a bone biopsy was carried out in the site of implant insertion. Each sample was histologically and immunohistochemically examined. Histological evaluation showed a complete bone formation for group II, partial ossification for group I, and moderate ossification for group III. Immunohistochemical analysis demonstrated a statistically significant difference between the three groups, and the best clinical result was obtained with a mixture of bCGF and autologous bone

Alternative Approaches to Urban Regeneration and Infill Planning: Case Turku, Finland

In Finland, cities consider infill development as a means for urban regeneration in existing suburbs. However, the preconditions for development may vary: some areas are more attractive for infill development projects than others. Therefore, cities must align their urban regeneration approaches with the specifics of the context. This paper builds on the notions that the prevailing growth-dependent urban planning paradigm is not functional in areas demarcated by low growth or stagnation. Planning that seeks to bring value for the localities by appreciating their strengths and non-monetary assets might provide grounds for alternative planning approaches. From these starting points, we explore how Finnish urban planners align their urban regeneration approaches with different contexts. We aim at identifying when the growth-dependent approach is used, whether alternative approaches are deployed, and what are their underlying logics. Our analytical framework originates from organizational learning theory of action inquiry. It explains how urban regeneration visions, strategies and actions are adjusted to low growth contexts. The empirical material consists of three urban regeneration cases in the Finnish City of Turku. As a result, three approaches to urban regeneration with different emphases on infill development are depicted and discussed. The growth-dependent approach is used in areas with strategic importance for the City, and possibilities for urban growth. Alternative approaches seek to support local development initiatives or inspire development in areas where it does not yet exist. The contribution of this exploratory paper is to demonstrate that urban planners in Finland deploy alternatives to growth-dependent planning and provide conceptualizations of alternative planning approaches

Rapid removal of ammonium from domestic wastewater using polymer hydrogels

To date, technologies to recover ammonium from domestic wastewater from the mainstream have not found widespread application. This is largely due to the low ammonium concentrations in these wastewater streams. This paper reports on the use of polymer hydrogels for rapid sorption of ammonium from domestic wastewater coupled with efficient regeneration by mild acid washing. The sorption capacity of the hydrogel was 8.8-32.2 mg NH4-N/g, which corresponds to removal efficiencies ranging from 68% to 80% NH4-N, increasing proportionally with the initial ammonium concentration. It was, however, unaffected by changes in pH, as the sorption capacity remained constant from pH 5.0-8.0. Importantly, effective regeneration of the hydrogels under mildly acidic conditions (i.e. pH 4.0) was demonstrated with minimal loss in sorption performance following multiple sorption/desorption cycles. Overall, this study highlights the potential of low-cost polymer hydrogels for achieving mainstream ammonium recovery from domestic wastewater

Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid-spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels allowing us to observe the deformation modes over longer periods of time. We found increasing mechanical fluctuations which break the toroidal symmetry and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to single cell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellular actin ring assembled along the toroid's inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin- driven length fluctuations of supra-cellular {\alpha}-actin structures (myonemes) in the outer cell-layer.Comment: 19 pages and 8 figures, submitted to New Journal of Physic

Establishment of in vitro tissue cultures from Echinacea angustifolia D.C. adult plants for the production of phytochemical compounds

SUMMARY The establishment of in vitro cultures of Echinacea angustifolia D.C. was obtained directly from sections of flower stalks of adult plants. The shoot formation was obtained from this plantmaterial placed on a modified MS basal medium named CH supplemented with 0.5 mg L1 6 benzylaminopurine (BA). The in vitro propagation procedure of E. angustifolia consisted of three distinct phases: an initial regeneration phase fromstalk sections (IP shoots on basal mediumwith 0.25 mg L1 BA), an elongation phase on active charcoal and an axillary proliferation of the shoots (AP shoots on basal medium with 0.5 mg L1 BA).Regenerating calli were established from leaves of in vitro shoots cultured on CH medium supplemented with 3 mg L1 BA and 0.5 mg L1 indole-3-butyric acid (IBA). Developed shoots from the callus cultures were subcultured on the CH medium with 0.5 mg L1 BA (leaf regenerated shoots: LR shoots). The secondary metabolite content of the in vitro plant material was compared with that of the greenhouse growing plants. The quali-quantitative LC-DAD-ESI-MS analysis on the extracts from axillary proliferation shoots (AP shoots) showed significant production of caffeic acid derivatives while leaf callus and LR shoots, accumulated mainly alkamides. These results showed that the proper choice of the procedures for in vitro multiplication allowed us to obtain plant biomass able to produce the active compounds typical of E. angustifolia plants

Tissue culture of oil palm : finding the balance between mass propagation and somaclonal variation

The oil palm (Elaeis guineensis Jacq.) is typically propagated in vitro by indirect somatic embryogenesis, a process in which somatic cells of an explant of choice are, via an intermediate phase of callus growth, induced to differentiate into somatic embryos. The architecture of the oil palm, lacking axillary shoots, does not allow for vegetative propagation. Therefore, somatic embryogenesis is the only alternative to seed propagation, which is hampered by long germination times and low germination rates, for the production of planting material. The current oil palm somatic embryogenesis procedure is associated with several difficulties, which are described in this review. The limited availability of explants, combined with low somatic embryo initiation and regeneration rates, necessitate the proliferation of embryogenic structures, increasing the risk for somaclonal variants such as the mantled phenotype. Several ways to improve the efficiency of the tissue culture method and to reduce the risk of somaclonal variation are described. These include the use of alternative explants and propagation techniques, the introduction of specific embryo maturation treatments and the detection of the mantled abnormality in an early stage. These methods have not yet been fully explored and provide interesting research field for the future. The development of an efficient oil palm micropropagation protocol is needed to keep up with the increasing demand for palm oil in a sustainable way. Mass production of selected, high-yielding palms by tissue culture could raise yields on existing plantations, reducing the need for further expansion of the cultivated area, which is often associated with negative environmental impacts