Resonant waves drive long-range correlations in fMRI signals

The fundamental principles driving spontaneous long-range correlations between distant brain areas - known as intrinsic functional connectivity - remain unclear. To investigate this, we develop an ultrafast functional Magnetic Resonance Imaging (fMRI) approach with unprecedented temporal resolution (38 milliseconds) in the rat brain. We detect a repertoire of principal components exhibiting standing wave properties, i.e., with phase relationships varying gradually across space and oscillating in time, driving in- and anti-phase synchronization across distinct cortical and subcortical structures. The spatial configuration, stability and peak frequency of these standing waves is found to depend on the sedation/anaesthesia state, with medetomidine sedation revealing the most stable (i.e., less damped) standing waves, resonating at frequencies extending up to 0.25 Hz. Our findings show that the complex activity patterns observed in resting-state fMRI signals result from the superposition of standing waves, supporting the hypothesis that intrinsic functional connectivity is inherently associated to resonance phenomena.

IL-25 Induced ROS-Mediated M2 Macrophage Polarization via AMPK-Associated Mitophagy

Interleukin (IL)-25 is a cytokine released by airway epithelial cells responding to pathogens. Excessive production of reactive oxygen species (ROS) leads to airway inflammation and remodeling in asthma. Mitochondria are the major source of ROS. After stress, defective mitochondria often undergo selective degradation, known as mitophagy. In this study, we examined the effects of IL-25 on ROS production and mitophagy and investigated the underlying mechanisms. The human monocyte cell line was pretreated with IL-25 at different time points. ROS production was measured by flow cytometry. The involvement of mitochondrial activity in the effects of IL-25 on ROS production and subsequent mitophagy was evaluated by enzyme-linked immunosorbent assay, Western blotting, and confocal microscopy. IL-25 stimulation alone induced ROS production and was suppressed by N-acetylcysteine, vitamin C, antimycin A, and MitoTEMPO. The activity of mitochondrial complex I and complex II/III and the levels of p-AMPK and the mitophagy-related proteins were increased by IL-25 stimulation. The CCL-22 secretion was increased by IL-25 stimulation and suppressed by mitophagy inhibitor treatment and PINK1 knockdown. The Th2-like cytokine IL-25 can induce ROS production, increase mitochondrial respiratory chain complex activity, subsequently activate AMPK, and induce mitophagy to stimulate M2 macrophage polarization in monocytes.

Extracellular Signalling Modulates Scar/WAVE Complex Activity through Abi Phosphorylation

The lamellipodia and pseudopodia of migrating cells are produced and maintained by the Scar/WAVE complex. Thus, actin-based cell migration is largely controlled through regulation of Scar/WAVE. Here, we report that the Abi subunit—but not Scar—is phosphorylated in response to extracellular signalling in Dictyostelium cells. Like Scar, Abi is phosphorylated after the complex has been activated, implying that Abi phosphorylation modulates pseudopodia, rather than causing new ones to be made. Consistent with this, Scar complex mutants that cannot bind Rac are also not phosphorylated. Several environmental cues also affect Abi phosphorylation—cell-substrate adhesion promotes it and increased extracellular osmolarity diminishes it. Both unphosphorylatable and phosphomimetic Abi efficiently rescue the chemotaxis of Abi KO cells and pseudopodia formation, confirming that Abi phosphorylation is not required for activation or inactivation of the Scar/WAVE complex. However, pseudopodia and Scar patches in the cells with unphosphorylatable Abi protrude for longer, altering pseudopod dynamics and cell speed. Dictyostelium, in which Scar and Abi are both unphosphorylatable, can still form pseudopods, but migrate substantially faster. We conclude that extracellular signals and environmental responses modulate cell migration by tuning the behaviour of the Scar/WAVE complex after it has been activated.

Virtual Environments as Medium for Laypeople’s Communication and Collaboration in Urban Design

<p>The distance between urban design processes and outcomes and their communication to stakeholders and citizens are often significant. Urban designers use a variety of tools to bridge this gap. Each tool often places high demands on the audience, and each through inherent characteristics and affordances, introduces possible failures to understand the design ideas, thus imposing a divergence between the ideas, their communication and the understandings. Urban design is a hugely complex activity influenced by numerous factors. The design exploration process may follow established design traditions. In all instances, the medium in which the exploration takes place affects the understanding by laypeople. Design tools are chosen, in part, to facilitate the design process. Most urban design community engagement does not use Virtual Environments (VE) as a means of communication and participation in the early stage of the design generation. There has been little research on how the use of VE for urban design can engage laypeople as contributors to the design process. It has been suggested that VE instruments can allow laypeople to express, explore and convey their imagination more easily. The very different nature of perceptual understanding of VE and its capability to produce instant 3D artefacts with design actions may allow laypeople to generate meaningful design ideas. An experiment setup has developed to leverage laypeople in authentic design collaboration. This thesis examines in the context of New Zealand’s National Science Challenge ‘Building Better Homes, Towns and Cities’ the drivers of change that contribute to the shaping of places, development and design of future neighbourhoods. A series of experiments have been conducted in the site of a neighbourhood to investigate the relative effectiveness of immersive VE to facilitate people in collaborative urban design. The findings support the hypothesis that VE with the generation of 3D artefacts enhances design communication for laypeople to design an urban form for their neighbourhood. The thesis concludes by discussing how New Zealand’s future neighbourhoods can be shaped and developed with VE assisted participatory urban design.</p>

Virtual Environments as Medium for Laypeople’s Communication and Collaboration in Urban Design

<p>The distance between urban design processes and outcomes and their communication to stakeholders and citizens are often significant. Urban designers use a variety of tools to bridge this gap. Each tool often places high demands on the audience, and each through inherent characteristics and affordances, introduces possible failures to understand the design ideas, thus imposing a divergence between the ideas, their communication and the understandings. Urban design is a hugely complex activity influenced by numerous factors. The design exploration process may follow established design traditions. In all instances, the medium in which the exploration takes place affects the understanding by laypeople. Design tools are chosen, in part, to facilitate the design process. Most urban design community engagement does not use Virtual Environments (VE) as a means of communication and participation in the early stage of the design generation. There has been little research on how the use of VE for urban design can engage laypeople as contributors to the design process. It has been suggested that VE instruments can allow laypeople to express, explore and convey their imagination more easily. The very different nature of perceptual understanding of VE and its capability to produce instant 3D artefacts with design actions may allow laypeople to generate meaningful design ideas. An experiment setup has developed to leverage laypeople in authentic design collaboration. This thesis examines in the context of New Zealand’s National Science Challenge ‘Building Better Homes, Towns and Cities’ the drivers of change that contribute to the shaping of places, development and design of future neighbourhoods. A series of experiments have been conducted in the site of a neighbourhood to investigate the relative effectiveness of immersive VE to facilitate people in collaborative urban design. The findings support the hypothesis that VE with the generation of 3D artefacts enhances design communication for laypeople to design an urban form for their neighbourhood. The thesis concludes by discussing how New Zealand’s future neighbourhoods can be shaped and developed with VE assisted participatory urban design.</p>

Redox regulation of PTPN22 affects the severity of T cell dependent autoimmune inflammation

Chronic autoimmune diseases are associated with mutations in PTPN22, a modifier of T cell receptor signaling. As with all protein tyrosine phosphatases the activity of PTPN22 is redox regulated, but if or how such regulation can modulate inflammatory pathways in vivo is not known. To determine this, we created a mouse with a cysteine-to-serine mutation at position 129 in PTPN22 (C129S), a residue proposed to alter the redox regulatory properties of PTPN22 by forming a disulfide with the catalytic C227 residue. The C129S mutant mouse showed a stronger T cell-dependent inflammatory response and development of T cell dependent autoimmune arthritis due to enhanced TCR signaling and activation of T cells, an effect neutralized by a mutation in Ncf1, a component of the NOX2 complex. Activity assays with purified proteins suggest that the functional results can be explained by an increased sensitivity to oxidation of the C129S mutated PTPN22 protein. We also observed that the disulfide of native PTPN22 can be directly reduced by the thioredoxin system, while the C129S mutant lacking this disulfide was less amenable to reductive reactivation. In conclusion, we show that PTPN22 functionally interacts with Ncf1 and is regulated by oxidation via the non-catalytic C129 residue and oxidation-prone PTPN22 leads to increased severity in the development of T cell-dependent autoimmunity.Significance statementA hitherto unstudied aspect of PTPN22 biology is its regulation by cell redox states. Here we created a mouse model where PTPN22 was mutated to respond differentially to redox levels in vivo and found that PTPN22 function is regulated by reactive oxygen species and that redox regulation of PTPN22 impacts T-cell-dependent autoimmune inflammation.

Stiffness Analysis of Delaminated Composite Beams Using Roller Clamps

Composites are favored over other traditional materials in many aerospace applications because of their high stiffness and strength-to-weight ratio. Taylor made material properties can be achieved by scheming the structural parameters making the material light, high strength and durable. Present work deals with a novel approach to enhance the strength of a layered delaminated composite beam using roller clamps to improve stiffness by providing uniform transverse force. Composite beam stiffness significantly degrades due to adverse environmental condition, impact loading and delamination effect. Composite structures are prone to delamination during its life span. Therefore in depth knowledge is needed to find the effect of roller clamps on the dynamic behavior of beam with varying delamination sizes. Present approach will be useful to enhance the stiffness of composite structure with delamination. The free vibration of a clamped cantilever beam is investigated, and the results are compared to those of an unclamped and undelaminated beam. The findings are supported by experimentally obtained responses (modal analysis). Furthermore, the complex activity of the laminated structure is numerically computed and the obtained data is compared to those available in open literature to ensure correctness. The laminated composite beam’s static and free vibration responses are calculated using finite element simulation software (ANSYS).

DUT Guide on Supervision

The aim of this guide is to provide tips for supervisors on how to support students as active, independent and prepared participants who drive their own projects forward. It relates to supervision of projects at bachelor-, master- and PhD level. The underlying basis of the guide is twofold: 1) supervision is an increasingly complex activity that involves a demanding set of competences; 2) a good supervisor is a flexible supervisor who can adapt to different situations, student needs and levels of the curriculum.

Bioinspired Polypyrrole based Fibrillary Artificial Muscle with Actuation and Intrinsic Sensing Capabilities

Artificial muscles comprise a bunch of materials, composites and devices performing a similar behavior to biological muscles, since a mechanical actuation is produced while consuming a certain amount of energy. However, in order to mimic the multiple simultaneous functionalities of the natural muscles, i.e. the proprioception, new devices should be designed. A non-conventional, bioinspired device based on polypyrrole coated electrospun fibrous microstructures, which works simultaneously as artificial muscle and mechanical sensor is reported. A simple fabrication algorithm based on electrospinning, sputtering deposition and electrochemical polymerization produced electroactive aligned ribbon meshes with analogous characteristics as natural muscle fibers. These can simultaneously produce a movement (by applying an electric current/potential) and sense the effort of holding weights (by measuring the potential/current while holding objects up to 24 mg). The amplitude of the movement decreases by increasing the load, a behavior similar with natural muscles. Moreover, when different weights were hanged on the device, it senses the load modification, demonstrating a sensitivity of about 6 mV/mg for oxidation and 3 mV/mg for reduction. These results are important since simultaneous actuation and sensitivity are essential for complex activity. Such devices with multiple functionalities can open new possibilities of applications as smart prosthesis or lifelike robots.