13553 research outputs found
Sort by
Proving excluded-minor characterisations using detachable pairs
No full textLet M be an excluded minor for the class of GF(4)-representable matroids. We give an independent proof, using results on detachable pairs that, except for a single edge case, |E(M)| ≤ 14. Moreover, we compute all excluded minors up to size 10. We also define a class M consisting of matroids obtained by extending the cycle matroid M(Kn) via the principal modular cut consisting of two non-adjacent edges, and their minors. We show that members of this class are representable over all fields of size at least 4, that a maximum-sized simple rank-r member of M has size at most (r + 2)(r + 1)/2 - 1, and that the class is not closed under duality or ∆-Y exchange..</p
Radiation-induced Attenuation in Standard Optical Fibers at Cryogenic Temperatures: Dose Rate, Temperature, and Photobleaching Interdependence
No full textThe use of optical fiber sensors in ionizing radiation environments is complicated by radiation-induced attenuations (RIAs) that cause significant signal loss as the cumulative radiation dose increases. Moreover, the RIA growth kinetics are strongly dependent on the temperature of irradiation and the intensities of the probe and/or photobleaching lights. Herein, we experimentally investigated the interdependence of the high-dose RIA, radiation dose rate (up to 8.7 Gy s-1), irradiation temperature (down to 15 K), and photobleaching power, in standard optical fibers (SMF28e+). Generally, the RIA increased as a function of dose rate and decreased as functions of temperature and photobleaching power. The experimental high-dose (i.e., saturation) RIA data were fit to a simple kinetic model with quantitative accuracy. Thus, we validate the model, demonstrating that the model accurately captures the interdependence of three key experimental parameters. Using a single set of fiber-specific constants, the saturation RIA was accurately calculated over a broad range of dose rates, temperatures, and photobleaching powers, and across distinct experiments
IUCN Strategy, Policy and Programme on Antarctica and the Southern Ocean
No full textThis strategy has been developed by the IUCN Council Taskforce on Antarctica and the Southern Ocean. It aims to address the threats and pressures on the region, while also identifying the particular role(s) that IUCN can appropriately play and which ones it can lead.
Prof Iorns is the Chair of this Taskforce of the International Union for Conservation of Nature
Hierarchical Dynamic Capabilities in Digital Transformation: An MNE Orchestration Framework
No full textABSTRACT Rapid technological advancements and global economic shifts have catalysed an era of digital transformation, confronting multinational enterprises (MNEs) with unprecedented challenges and opportunities. While only 22% of organisations achieve and sustain improved performance through digital transformations, the strategic significance of this shift is evident, with digital platforms expected to play a crucial role in market adaptation for 75% of industry leaders by 2025. This study develops a comprehensive theoretical framework that integrates dynamic capabilities, orchestration processes, and business model innovation to understand how MNEs successfully navigate digital transformation.Drawing on the systematic analysis of five manufacturing MNEs over multiple years, this research examines three critical areas: (1) how different levels of dynamic capabilities interact with ordinary capabilities in enabling digital transformation; (2) the mechanisms through which manufacturing MNEs orchestrate digital transformation through product-to-solution centric models, customer engagement, and ecosystem participation; and (3) how these orchestration processes drive business model innovation through value proposition reconfiguration, data-driven service evolution, and revenue stream transformation. Employing a post-positivist paradigm, this study conducts a longitudinal analysis of multiple cases, examining annual reports from leading industrial MNEs across wires & cables and bearing manufacturing industries over an eight to eleven-year period.The study advances theoretical understanding across three core domains. First, it extends the dynamic capabilities framework by revealing distinct roles and interactions of different capability levels, identifying a 'cross-border capability enhancement cycle' between dynamic and ordinary capabilities. Second, it advances the orchestration framework by establishing distinct patterns in how manufacturing MNEs orchestrate digital transformation and revealing specific mechanisms for global orchestration. Third, it contributes to business model innovation literature by identifying three transformative patterns in manufacturing contexts. These insights offer important implications for both theory and practice in digital transformation and international business.Keywords: Multinational Enterprises (MNEs), Digital Transformation, Dynamic Capabilities, Orchestration, Business Model Innovation</p
Amide Couplings of Sugar Amino Acids and their Sulfates: Toward Heparan Sulfate Mimetics
No full textHeparan sulfate (HS) is a sulfated glycosaminoglycan with huge therapeutic potential. It is produced by all animal cells and plays roles in many cell signalling, regulatory, and proliferation processes. Nature produces HS as heterogenous populations with glycans of various lengths and sulfation patterns. This makes characterisation of HS and determination of structure-activity relationships extremely difficult. Unlike the widely used therapeutic heparin, HS is available in only limited supply, generally from commercial heparin side streams. Homogenous HS populations can be provided by synthesis but due to the complexity of these structures, preparation of even small oligomers takes much effort and resource. Synthetically more accessible HS mimetics can help bridge the gap.Linking carbohydrate moieties using amide linkages rather than glycosyl linkages is one way to simplify oligomer synthesis. Amide bonds are routinely generated in peptide synthesis through reactions that are high yielding and well established. Employing sugar amino acids (SAAs) as starting components can facilitate the assembly of oligomeric HS mimetics. In this way, oligomers with defined sulfation patterns can be prepared and used to discern structure-activity relationships.Sulfated SAAs are highly polar compounds which are difficult to handle and manipulate and there are limited examples of amide couplings of sulfated SAAs in the literature.In this work, sulfated SAA monomer building blocks suitable for participating in amide couplings were prepared. Synthetic routes to these materials were established, including the reliable installation of sulfate groups. Then, three approaches to amide bond formation between sulfated SAAs were explored: couplings in the solution phase, couplings on the solid phase, and solution phase polymerisations.Methodology was developed which enabled the solution phase coupling of sulfated SAAs with unsulfated SAAs. Key to these reactions were the choice of coupling reagents and the salt form of the SAA sulfates. A range of techniques were investigated for the purification of the sulfated materials from other highly polar reaction components including silica gel chromatography, dialysis, acidic resin work-up, and chemical derivatisations. The limit of the coupling technology was determined where amide formation could not be effected between two sulfated SAAs in solution.Next, coupling reactions of sulfated SAAs on the solid phase were investigated. This involved extensive resin loading studies of SAAs, in which the stability of sulfated SAAs to solid phase conditions was demonstrated through loading and recovery assessments. Coupling reactions were realised, but again amide bonds between sulfated coupling partners remained elusive.Sulfated SAA polymers were synthesised using an undirected solution phase coupling process and a post-polymerisation sulfation strategy. Characterisation of these sulfated polymers was undertaken, and their degrees of sulfation and polymerisation assessed. Pre-polymerisation sulfation strategies once again illustrated the reluctance of sulfated SAAs to form amide bonds with one another.</p
Psychostimulant-Associated Reward, Reinforcement, and Habit Formation in Wild-Caught New Zealand Planaria
No full textSubstance use disorder (SUD) presents a major and rapidly evolving global health crisis, with severe consequences for individuals, communities, and healthcare systems. As the global drug addiction landscape grows in complexity, so too does the need for innovative research tools to explore the mechanisms driving drug abuse and relapse. Invertebrate models such as the flatworm Planaria offer unique advantages for this purpose. Their simple neurobiology combined with key similarities to vertebrates, such as conserved neurotransmitter systems and the capacity for reward-based learning, makes them an attractive upcoming model. Despite a growing literature base, prior research has mainly focused on Pavlovian conditioning, with limited exploration of operant conditioning or more complex addiction-related behavioural patterns such as habit formation. Moreover, psychostimulant behavioural research on planaria has focused largely on cocaine with little attention to the other major psychostimulant of abuse, methamphetamine. Furthermore, virtually no studies have explored the use of wild-caught planarian samples in behavioural experiments.To address these gaps, the present study investigated methamphetamine-associated conditioning, learning, and habit formation in wild-caught New Zealand planaria. We employed paradigms adapted from mammalian addiction research: conditioned place preference (CPP), and self-administration in the Y-maze. CPP findings showed that 10μM methamphetamine induced Pavlovian conditioning, which extinguished in absence of the drug and was promptly reinstated following brief re-exposure. In the Y-maze, reinforcement with 10μM methamphetamine produced operant drug-seeking behaviour, which was also responsive to extinction and reinstatement. Our habit formation experiments revealed that planaria overtrained on the operant Y-maze task displayed greater resistance to extinction and reduced sensitivity to reward devaluation. These phenomena are consistent with the transition from goal-directed to stimulus-response behaviour in the mammalian habit formation literature. Our findings provide the first evidence of drug-associated habit formation in invertebrates, and highlight the value and practicality of using wild-caught planarian species as cost-effective, accessible, and valid invertebrate models in addiction and other behavioural research. The study’s limitations are discussed, and recommendations made for future researchers to build upon our findings and improve our methodologies.</p
Superconducting bearing spin-down experiment
No full textVideo of a superconducting spin-down experiment recorded at Robinson Research Institute, Victoria University of Wellington New Zealand. </p
Development and Application of Advanced Ultrafast Spectroscopy
No full textUltrafast spectroscopy is a critical tool for probing the photophysics of advanced materials. An optimal system requires high temporal resolution, broadband detection, high signal-to-noise ratio, and rapid data acquisition, all of which depend on the choice of light source. While titanium-sapphire (Ti-sapphire) lasers deliver short and high-energy pulses, their inherent nature restricts simultaneous operation at high power and high repetition rates. In contrast, Ytterbium-based (Yb-based) lasers offer a compact, stable, and low-maintenance alternative. Their significantly higher repetition rates potentially improve signal-to-noise ratio and accelerate data acquisition, addressing the major drawbacks in Ti-sapphire-based spectroscopic systems. However, their longer pulse duration necessitates external light source for temporal compression to achieve optimal time resolution to probe ultrafast processes. To overcome this limitation, this thesis develops several spectroscopic systems integrating Yb-based lasers with advanced external light sources to provide high-performance measurements. We anticipate these setups will establish a new standard for ultrafast spectroscopy.First, transient absorption spectroscopy (TAS) systems were developed using Yb-based lasers, with performance further enhanced by integrating multiple-plate compression (MPC) light sources. This setup achieves a temporal resolution of 3.2 fs with an octave-spanning detection range. The high-intensity and broadband spectrum of MPC enables flexible wavelength selection via commercial spectral filters, eliminating the need for complex optical parametric amplification. The high brightness of MPC facilitates measurements of materials with strong absorption, reflection loss, or scattering. Additionally, the red-shifted central wavelength of Yb-based lasers compared to Ti-sapphire lasers is particularly advantageous for studying near-infrared (NIR) photoresponse. Based on these advantages, we established a platform for the research and development of NIR optoelectronic materials. This is demonstrated by direct device ultrafast TAS measurements on a state-of-the-art NIR organic photodetector under conditions with and without an external bias to simulate operational scenarios and elucidate the photophysical mechanisms underlying its exceptional performance.Second, Yb-based lasers paired with fiber amplifiers and MPC light sources were employed to improve the performance of transient grating photoluminescence spectroscopy (TGPLS). These advanced light sources deliver ultrashort pulses and elevated repetition rates, enabling broadband time-resolved photoluminescence (TRPL) measurements with excellent temporal resolution, high signal-to-noise ratio, and rapid data acquisition. To validate these capabilities, the TGPLS system was applied to study an organic light-emitting material, Pt(II) complex 4H. This investigation successfully captured vibrational coherence during the fast intersystem crossing and elucidated excited-state deactivation pathways via phosphorescence.A novel merged spectroscopic system was developed by integrating TAS and TGPLS within a single experimental setup based on a Yb-based fiber amplifier. This unified configuration enables broadband detection in both techniques with similar temporal resolution of <200 fs and identical excitation conditions, minimizing discrepancies between measurements. These features allow for direct comparison of spectral and kinetic features obtained through global fitting. With these advantages, we study the ultrafast solvation processes in a laser dye, where distinct spectral evolution over time were captured by the two spectroscopic methods, yet their global fitting results exhibited identical features. Overall, this thesis presents significant advancements in ultrafast spectroscopy by leveraging Yb-based laser systems and next-generation light sources. These innovations enhance detection sensitivity, reduce data acquisition time, and expand detection bandwidth, establishing a robust foundation for future ultrafast spectroscopic research and the exploration of emerging materials.</p
Exploring the Emotional Experiences of Non-Provider Health Professionals Involved in Assisted Dying in New Zealand
No full textAssisted dying (AD) has been a subject of ethical, legal, and emotion-fuelled debate, particularly among healthcare professionals. While much research has focused on the experiences of providers directly involved in AD, less is known about the emotional experiences of non-provider health professionals (NPHPs) who engage with patients and families in this context. This study explores the emotional experiences of NPHPs involved in AD in New Zealand (NZ), utilising Lazarus’s cognitive-motivational-relational theory (CMRT) and Hochschild’s concept of emotional labour as theoretical frameworks. A Heideggerian interpretive phenomenological approach as an overarching research paradigm and reflexive thematic analysis (RTA) were employed to contextualise and analyse the data collected through semi-structured interviews with ten NPHPs practising in NZ. The findings provide insight into the unique emotional experiences and challenges faced by NPHPs and the coping strategies they employed by highlighting five key themes: (1) finding meaning in the NPHP role, (2) the impact of health and institutional regulations on NPHP’s lived experiences, (3) concerns surrounding AD, (4) problem-focused coping and (5) emotion-focused coping strategies. These findings reveal the personal, professional and contextual factors that shape NPHPs’ appraisals and coping strategies. While many participants discovered the meaning and consistency of their roles, institutional ambiguity, stigmatisation and emotional labour remained ongoing challenges. These findings emphasise the necessity of targeted psychosocial and practical support, clear policy guidance and culturally appropriate training to promote sustainable and compassionate AD-related care. Findings also highlight the need for future research to explore broader perspectives and long-term impacts on NPHPs to inform appropriate practices in healthcare settings.</p
Access Repository Dashboard
Do you manage Victoria University of Wellington? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!