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Shifting skies: A cross-country investigation of evolution of public perception toward urban air mobility through Twitter (X) discourse
No full textUrban air mobility (UAM) is increasingly being recognised as a promising response to the challenges of rapid urban expansion and its negative externalities. While technological advancements in vertical take-off and landing (VTOL) aircraft have accelerated development in this space, the widespread adoption of UAM services hinges on societal acceptance driven by public perceptions. Understanding these perceptions, especially their variation across regions and over time, is critical for developing policies to maximise their adoption rate. This study leverages a large-scale and long-term Twitter dataset to discern the spatio-temporal evolution of public perceptions towards UAM. To this end, we employed a combination of machine learning (ML) and a large language model (LLM) for performing sentiment classification. Subsequently, sentiment polarities are integrated with time series analysis, indicating the prevalence of positive perception for most of the last decade, while detecting the effect of various real-world events. In terms of spatial K-means clustering results, it reveals four clusters of countries with distinct characteristics. For example, people in countries like the USA and Australia are observed to be highly opinionated towards UAM, while public discourse in Germany and India is more neutral. Finally, dynamic topic modelling coupled with an LLM-based representation uncovers underlying themes of public discourse. Topic model findings underline three major global themes: (1) industry innovation and testing, (2) unmanned aviation systems, and (3) mobility benefits. Furthermore, we identified in some cases that local themes driven by specific incidents have a more substantial effect in shaping the preferences than the generic global ones. The paper hence contributes to the literature by providing the first global-level dynamic spatio-temporal assessment of future UAM services. The insights are expected to offer valuable policy guidance for policymakers, regulators, and industry stakeholders aiming to improve the public acceptance of UAM technologies and consequently the uptake
Strategic design of parcel locker networks for urban delivery
No full textThis paper focuses on the strategic design of a Parcel Locker (PL) network in the context of last-mile delivery. While PLs are emerging as a promising alternative to home delivery, their implementation poses practical challenges, including high deployment costs, inefficient capacity utilization, replenishment scheduling, and coordination with end users. To address this, we consider a network consisting of a depot, candidate locations for PLs, and service regions, each representing a group of customers with known aggregate daily demand distributed across multiple periods. Each period corresponds to a time window preferred by some customers for parcel pickup. The problem extends the classical location-routing problem by incorporating a multi-period horizon, a two-echelon network structure, and flexible replenishment planning. The objective is to minimize upfront strategic costs and anticipated operational costs over the network’s economic life. Strategic decisions concern selecting locations and capacities for PLs, and the size of a fleet to replenish PLs from the depot. Operational decisions, which can be revisited after the network is deployed, involve planning replenishment and routes over a single-day, multi-period horizon. The problem is formulated as a mixed-integer linear program and solved using a variable neighborhood search embedded in a branch-and-cut framework, leveraging tailored valid inequalities and local search moves. Computational experiments, along with a case study in Chicago using real data from Amazon, demonstrate that incorporating expected operational costs into network design process leads to more cost-efficient PL networks. Moreover, flexibility in replenishment planning affects both operational cost and network configuration, leading to further improvements in overall system efficiency
A bioactive hydrogel harnessing the regenerative potential of notochordal cells serves as instructive cell carrier for nucleus pulposus repair
No full textNatural biomatrices are popular owing to their ability to mimic tissue-specific biological properties. These properties are crucial for the intervertebral disc, a particularly demanding tissue whose degeneration is a major cause of chronic lower back pain. Degeneration starting within the core of the disc, the nucleus pulposus (NP), is marked by the loss of notochordal cells (NCs) and associated-healthy extracellular matrix. The regulative potential of the NC-secretome was exploited through a PEG-based hydrogel formulated with decellularized porcine notochordal cell matrix (dNCM). Even under conditions which mimic the degenerate niche, the hydrogel supported maintenance of the native porcine NC phenotype, well-known for the difficulty in preserving their vacuolated phenotype. dNCM-PEG hydrogel carrying human mesendodermal progenitors (hMEPCs; iPS-derived and capable of differentiating into NCs), was injected into NP explants with enzymatically induced matrix degradation and subjected to dynamical loading. hMEPCs engrafted successfully and a healthy disc cell phenotype was observed. Injection of dNCM+hMEPCs into degenerated discs in a pilot experimental dog study indicated that ∼7% of the 0.5 million hMEPCs engrafted. Single cell RNAseq analysis showed over 30% of the engrafted and recovered hMEPCs co-expressed Collagen Type II and Aggrecan consistent with a functional phenotype. No tumorigenic or systemic immunogenic side effects were observed. At the tissue level, TBXT expression, as well as matrix quality, were enhanced in the treated degenerate disc tissues. Together, this study highlights the translational potential of combining cell-based therapies with a bioactive material containing part of the NC secretome, warranting further development and validation
Securing Bangladesh's nuclear future: is the regulated asset base model the answer to address project corruption?
No full textBangladesh's goal of achieving high-income status by 2041 requires dependable, low-emission, and affordable energy. With near-universal grid coverage and increasing demand, nuclear energy is a strategic asset for long-term baseload supply. However, the existing financing model, typified by the country's most expensive $12.65 billion Rooppur project which is 90% Russian loan funded, creates national fiscal strain, inflated costs, and systemic corruption risks. The regulated asset base (RAB) model, a framework in utility regulation, offers a viable alternative. By distributing a small levy among Bangladesh's roughly 37 million electricity bill payers, the RAB model can mobilize significant low-cost capital. This reduces reliance on foreign debt and enforces disciplined, transparent project management from the start. This perspective article expects that implementing a RAB model for future nuclear projects in Bangladesh would potentially reduce corruption risks, attract healthy international competition, and lower the ultimate cost of electricity. Our analysis references global examples, specifically the United Kingdom's Sizewell C and Thames Tideway Tunnel projects, and presents a Bangladesh-specific framework. Strengthening the capacity and independence of local regulator (Bangladesh Energy Regulatory Commission [BERC]) is essential to this shift, acting as the guarantor for both investors returns and consumer protection. The RAB model provides Bangladesh an alternative path to energy security, fiscal prudence, and clean power, provided immediate regulatory reform is adopted
Long-term effects of vegetation cover on the rehabilitation of lead/zinc mine tailings
No full textPb/Zn sulfide ore is extracted from carbonate host rock by milling to grainsizes <120 μm and separation by flotation. This produces large volumes of near neutral pH tailings that must be carefully managed due to regulatory concern about the residual Pb and Zn concentrations (up to ∼0.3 % by wt. of each) and trace concentrations of other potentially toxic elements. To prevent dust formation, vegetation cover is established on inactive areas of the tailings management facility (TMF). This paper reports the changes in the chemical and microbiological composition of the tailings as a function of both time and depth.
Over the course of eight years, there is progressive oxidation of pyrite in the tailings, and accumulation of soil organic matter in the surface layers. The mobility of most potentially toxic elements is reduced due to sorption to ferric oxyhydroxides formed as a result of pyrite oxidation, although Cu is more mobile in surface layers probably due to formation of dissolved organic carbon complexes. The microbial community diversity in the surface layer increased with the age of the tailings and was similar to natural calcareous soil after 8 years. At this age the functional profile (functional diversity) of the community was similar to that of natural calcareous soil, despite differences remaining in taxonomic composition. Development of soil-like properties in the surface layer, such as increased soil organic matter content and a soil-like microbial community, suggest that the vegetation cover will be self-sustaining. Therefore, revegetation is a viable option for TMF closure planning
Rapid economic impact assessment of nature-based solutions: Illustration of a co-constructed approach
No full textAmongst the multiple advantages attributed to nature-based solutions (NBS) over conventional and grey infrastructure, is their characterisation as economically efficient, i.e. that the benefits that they generate outweigh their costs. However, surprisingly little attention has been paid so far to generating quantified evidence to support this claim in the form of comprehensive cost-benefit analysis informing actual and specific environmental decisions in given territories. In the absence of such evidence, current enthusiasm for NBS might result in unfavourable decisions, disappointment and abandonment. In this paper, we illustrate a co-constructed approach developed in close collaboration with policy-makers and involving a range of stakeholders. This approach formally evaluates the well-being impacts of adopting NBS versus non-NBS alternatives for the mitigation of agricultural impacts in the ecologically stressed Mar Menor lagoon (Spain), building-up the evidence base of the economic efficiency of NBS. More importantly, the paper illustrates how to undertake rapid economic impact assessments that, when exposed and co-constructed with a range of stakeholders in participatory processes, can support complex policy decisions in response to climate and environmental emergencies in ways that are robust, transparent and socially acceptable. By maintaining scientific rigor while simplifying data demands, rapid co-constructed economic impact assessments can not only integrate ecosystem services and economic efficiency reasoning into environmental governance but can also serve as boundary objects for consensus building, awareness raising and collective experiential learning. This is of particularly critical importance in times of growing polarisation over environmental challenges
Leveraging Employees' Social Capital for Organizational Resilience in Small and Medium-Sized Enterprises: The Role of High-Involvement Work Practices
No full textEmployees' bridging social capital (EBSC), conceptualized as the collective bridging social capital that employees bring into the organization, has been recognized as a potential resource for fostering organizational resilience (i.e., the ability to survive and thrive when confronted with unexpected disruptions and challenges), especially for small and medium-sized enterprises (SMEs) operating in a turbulent business environment. However, the questions of how and when EBSC relates to organizational resilience remain underexplored. Drawing on dynamic capabilities theory, we propose that knowledge sharing—a dynamic and emergent process where knowledge is introduced, exchanged, combined, and integrated within organizations—represents a key process through which EBSC may be associated with organizational resilience. We further propose that this mechanism is stronger in organizations that extensively implement high-involvement work practices (HIWPs). Using data from 1131 participants (including top management team members, middle-level managers, and entry-level employees) across 175 SMEs in Nigeria, we find that the relationship between EBSC and knowledge sharing, as well as the indirect association between EBSC and organizational resilience via knowledge sharing, is stronger when HIWPs are high rather than low. These findings highlight the importance of HIWPs in leveraging EBSC to enhance organizational resilience, providing practical insights for SMEs seeking to harness EBSC for organizational advantages
Supramolecular Diversity in Bis(acylhydrazone) Crystals: Linker Effects, Polymorphism, and Gelator Assemblies
No full textA series of previously unknown bis(acylhydrazone)s with aliphatic (zero to four CH2 units) and aromatic (phenylene substituted) linkers was synthesized and structurally characterized. Aliphatic derivatives exhibited distinct conformational geometries and packing motifs, with linker length critically affecting hydrogen bond interactions and energies. Aromatic derivatives revealed three polymorphs of the meta-substituted structure with two of the forms related by temperature. Additionally, a bis(acylhydrazone) low-molecular-weight gelator was crystallized, revealing a unique and impressive hydrogen-bonded framework with large water channels (952 Å3) and strong aliphatic and aromatic stacking interactions. These findings highlight the potential of bis(acylhydrazone)s in crystal engineering and supramolecular chemistry, especially in coformer design and selection, and supramolecular gelator applications
Social identity and cooperation co-evolve in a multilevel public goods game
No full textIn the real world people often face collective action problems at multiple scales, where they must choose between local and global cooperation. Unlike single public goods scenarios, which can be solved if enough players are willing to cooperate, multilevel collective action problems introduce an additional coordination challenge in working towards the same goals. Using a pre-registered, online behavioural experiment, we investigate how perceptions of social identity predict and covary with cooperation success in multilevel public goods games. We find that introducing a local cooperation option undermines global cooperation and exacerbates parochial biases, but that increasing the payoffs of global cooperation boosts global cooperation levels. We also see a performance-cohesion effect, whereby successful cooperation within groups is associated with increased social identification with that group. Overall, our findings point to the importance of social context for cooperation, social identity, and their interplay
Characterising the shear, stretch and in-plane bending response of a pure-unidirectional non-crimp fabric
No full textThe in-plane deformation kinematics of a pure-Unidirectional Non-Crimp Fabric (pure-UDNCF) is investigated using novel and existing experimental methods to characterise its shear, tensile, and in-plane bending responses under controlled loading. A pure-UDNCF is defined as a fabric in which stabilising tows are absent in the transverse direction relative to the primary tow orientation. The stitching threads in this fabric are made of polyamide, a highly compliant material that allows significant stretch, introducing a low-energy deformation mode that is relatively absent in biaxial engineering fabrics and quasi-UDNCFs (UDNCFs with inextensible stitching and transverse stabilising fibres). To fully characterise its forming behaviour, several novel testing methods are introduced that generate well-defined combinations of fabric shear, in-plane bending and stitch tensile strain. The total normalised axial force measured in the tests is subsequently decoupled into three contributions from shear, tensile strain in the stitch direction, and in-plane bending of the tows. An important finding is that when tested in the picture frame test, in-plane bending generates more resistance to specimen deformation than shearing of the fabric. The testing protocol and resulting data can be used to create appropriate constitutive models for pure-UDNCFs