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Investigation of installation stress level on the vertical and lateral loading behaviour of open-ended piles by centrifuge tests
No full textExtensive research has focused on quantifying the loading behaviour of 1g (g, gravitational acceleration rate) installed open-ended piles using centrifuges. However, the influence of installation stress level on loading behaviour is often ignored, with ramifications for the accuracy and validity of results. In this paper, a loading apparatus is developed to allow in-flight jacking of piles followed directly by vertical or lateral loading, without needing to stop the centrifuge, which facilitates maintaining the installation-related stress state. Model piles are installed at 50g and 1g, and the vertical and lateral responses are analyzed. The effect of pile installation stress level on the initial stiffness, resistance, and soil plug behaviour, is investigated. Results indicate that installation stress level has a more significant and non-uniform effect on pile vertical behaviour than lateral behaviour. Piles that are not fully installed at 50g can mobilize the same vertical resistance as those fully installed at 50g, provided they experience a minimum of 2D (D, pile diameter) in-flight installation length. The arching effect caused by soil plugging, and the denser sand state surrounding the pile toe, may provide higher vertical and lateral resistance for piles installed at 50g compared to those installed at 1g
Distinct origins of environmentally quenched galaxies in the core and outer virialised regions of massive clusters at 0.8 < < 1.5
Get PDFHigh-redshift ( ∼ 1) galaxy clusters are the domain where environmental quenching mechanisms are expected to emerge as important factors in the evolution of the quiescent galaxy population. Uncovering these initially subtle effects requires exploring multiple dependencies of quenching across the cluster environment, and through time. We analyse the stellar-mass functions (SMFs) of 17 galaxy clusters within the GOGREEN and GCLASS surveys between 0.8 9.5. The data are fit simultaneously with a Bayesian model that allows the Schechter function parameters of the quiescent and star-forming populations to vary smoothly with cluster-centric radius and redshift. The model also fits the radial galaxy number density profile of each population, allowing the global quenched fraction to be parameterised as a function of redshift and cluster velocity dispersion. We find the star-forming SMF to not depend on radius or redshift. For the quiescent population however, there is ∼ 2 evidence for a radial dependence. Outside the cluster core ( > 0.3 200), the quenched fraction above log (/M⊙) = 9.5 is ∼ 40 per cent, and the quiescent SMF is similar in shape to the star-forming field. In contrast, the cluster core has an elevated quenched fraction (∼ 70 per cent), and a quiescent SMF similar in shape to the quiescent field population. We explore contributions of ‘early mass-quenching’ and mass-independent ‘environmental-quenching’ models in each of these radial regimes. The core is well-described primarily by early mass-quenching, which we interpret as accelerated quenching of massive galaxies in protoclusters, possibly through merger-driven feedback mechanisms. The non-core is better described through mass-independent, environmental-quenching of the infalling field population
When can we detect lianas from space? Toward a mechanistic understanding of liana‐infested forest optics
Get PDFLianas, woody vines acting as structural parasites of trees, have profound effects on the composition and structure of tropical forests, impacting tree growth, mortality, and forest succession. Remote sensing could offer a powerful tool for quantifying the scale of liana infestation, provided the availability of robust detection methods. We analyze the consistency and global geographic specificity of spectral signals—reflectance across wavelengths—from liana-infested tree crowns and forest stands, examining the underlying mechanisms of these signals. We compiled a uniquely comprehensive database, including leaf reflectance spectra from 5424 leaves, fine-scale airborne reflectance data from 999 liana-infested canopies, and coarse-scale satellite reflectance data covering 775 ha of liana-infested forest stands. To unravel the mechanisms of the liana spectral signal, we applied mechanistic radiative transfer models across scales, establishing a synthesis of the relative importance of different mechanisms, which we corroborate with field data on liana leaf chemistry and canopy structure. We find a consistent liana spectral signal at canopy and stand scales across globally distributed sites. This signature mainly arises at the canopy level due to direct effects of more horizontal leaf angles, resulting in a larger projected leaf area, and indirect effects from increased light scattering in the near and short-wave infrared regions, linked to lianas' less costly leaf construction compared with trees on average. The existence of a consistent global spectral signal for lianas suggests that large-scale quantification of liana infestation is feasible. However, because the traits responsible for the liana canopy-reflectance signal are not exclusive to lianas, accurate large-scale detection requires rigorously validated remote sensing methods. Our models highlight challenges in automated detection, such as potential misidentification due to leaf phenology, tree life history, topography, and climate, especially where the scale of liana infestation is less than a single remote sensing pixel. The observed cross-site patterns also prompt ecological questions about lianas' adaptive similarities in optical traits across environments, indicating possible convergent evolution due to shared constraints on leaf biochemical and structural traits
Single-cell transcriptomics reveal how root tissues adapt to soil stress
Get PDFLand plants thrive in soils showing vastly different properties and environmental stresses1. Root systems can adapt to contrasting soil conditions and stresses, yet how their responses are programmed at the individual cell scale remains unclear. Using single-cell RNA sequencing and spatial transcriptomic approaches, we showed major expression changes in outer root cell types when comparing the single-cell transcriptomes of rice roots grown in gel versus soil conditions. These tissue-specific transcriptional responses are related to nutrient homeostasis, cell wall integrity and defence in response to heterogeneous soil versus homogeneous gel growth conditions. We also demonstrate how the model soil stress, termed compaction, triggers expression changes in cell wall remodelling and barrier formation in outer and inner root tissues, regulated by abscisic acid released from phloem cells. Our study reveals how root tissues communicate and adapt to contrasting soil conditions at single-cell resolution
Examining the Financial Impact of Biodiversity‐Related Reputational Disasters
Get PDFThis research investigates the reaction of financial markets to biodiversity-related corporate events, utilising an EGARCH model to assess the implications on stock returns and volatility. Results reveal that markets significantly respond to these events, demonstrating heightened sensitivity and volatility that underscore the financial relevance of biodiversity risks. We find that investors differentiate between events based on their novelty and severity, reflecting a nuanced valuation approach towards environmental information, highlighting the importance of transparency and the role of information asymmetry in market efficiency. Our findings advocate for stricter disclosure requirements and enhanced regulatory frameworks to improve market transparency concerning environmental risks. This research underscores the need for further integration of biodiversity considerations into financial decision-making and regulatory policies
Ultrafast ring-opening dynamics of 1,2-dithiane following ultraviolet absorption
Get PDFWe report results from a recent laser pump–probe study into the ultrafast ring-opening dynamics of 1,2-dithiane. Following absorption of a 290 nm photon, the nuclear dynamics were probed as a function of pump–probe delay on the femtosecond timescale by strong-field ionisation with an 800 nm probe pulse, resulting in production of a range of atomic and molecular fragment ions. The time-dependent yields of atomic fragment ions reveal evidence of coherent nuclear wavepacket dynamics corresponding to the previously proposed ‘Newton's cradle’ motion of 1,2-dithiane, in which repeated ring opening, structural inversion, and ring closing occurs on a timescale of ∼400-500 fs. Based on surface-hopping trajectory simulations of the non-adiabatic dynamics, we are able to rationalise the observed time-dependent ion yields in terms of a geometry-dependent variation in ionisation energy for the photoexcited 1,2-dithiane molecule
COVID-19 and urban poor communities in Metro Manila: Social vulnerability and the ‘pasaway’
Get PDFThis article examines the impact of the Philippine government's response to COVID-19 on urban poor communities in Metro Manila. The central government's response to COVID-19 was militarised and this left many socially vulnerable urban poor families with a dilemma. They faced either violating quarantine regulations and risking arrest in the pursuit of their livelihood or starving at home. Quarantine violators were cast in the role of 'pasaway' or 'undeserving poor' by President Duterte. Drawing on evidence from 38 interviews with community leaders, non-governmental organisations (NGOs) staff members and public servants, we argue that those most in need of social protection during the COVID-19 response were often the least likely to get it. We examine how local government agencies, NGOs, and those living in the communities worked towards meeting material needs and countered some of the effects of the militarisation of the pandemic
A Novel Underwater Wireless Power Transfer System Based on LCC-S Compensation Topology with Wide Soft-Switching Range
No full textUnder the influence of high sea conditions and dynamic marine environments, the compensation parameter values in the system are prone to fluctuations, potentially compromising the soft-switching stability. In addition, a significant proportion of the total loss in the three-phase wireless power transfer (WPT) system is attributed to the switching loss. To address these challenges, this article proposes a three-phase WPT system featuring a low-loss passive auxiliary network with an inductor-capacitor–capacitor-series (LCC-S) compensation topology. With the support of this passive auxiliary network, the system’s switches can achieve zero-voltage switching (ZVS) turn-on and ZVS turn-off across its wide load range while exhibiting insensitivity to fluctuations in compensation parameters. This article first analyzes the soft-switching communication mechanism of the proposed structure before designing the wide range soft-switching conditions and parameters for the system. Finally, an underwater three-phase WPT experimental prototype with a rated power of 1 kW is developed, and the results demonstrate the superiority of the proposed scheme
Microrheology of the cumulus-oocyte matrix using optical tweezers
Get PDFOptical tweezers have emerged as a powerful, versatile approach for a range of studies in cellular and molecular biology. A particular highlight has been its use for microrheology measurements in miniscule sample volumes. In this study, we demonstrate the application of optical tweezers to investigate the viscosity of the extracellular matrix surrounding mammalian oocytes and determine whether this is associated with oocyte developmental potential. By analysing the motion of a trapped particle, we can quantify the mechanical properties of this matrix, thus overcoming limitations of traditional passive microrheology techniques that rely on free diffusion. We utilise two maturation methods—in vivo and in vitro—to generate oocytes with differing developmental potential. Our findings indicate that oocytes matured in vivo exhibit higher viability post-fertilisation compared to their in vitro counterparts and we establish a positive correlation between extracellular matrix viscosity and oocyte developmental potential. This work demonstrates that optical tweezers are a novel, non-invasive tool for assessing oocyte quality, contributing to valuable insights to the field of reproductive biology
Process design and techno-economic risk assessment of a solid sorbent silica polyethyleneimine (SI-PEI) CCS process integrated into a cement plant
No full textThe paper examines the design and techno-economic risk assessment of a carbon capture and storage (CCS) process using silica-polyethyleneimine (Si-PEI) as a solid sorbent. This CCS process was integrated into a cement plant with an annual production of one million tonnes of clinker, representing the EU's average plant size. The study benchmarks the Si-PEI CCS process against the monoethanolamine (MEA) CCS process, assuming both systems capture 90 % of the plant's annual emissions. Aspen Plus models, validated through literature and experiments, simulated the CCS processes. A preliminary hazard analysis assessed technical risks, while economic risks were quantified using the Monte Carlo method, considering uncertainties in feedstock supply cost, cement selling price, solvent/sorbent cost, energy cost, and emission allowance price. The Si-PEI CCS unit emerged as the most favourable investment, being less expensive and technically safer than the MEA CCS unit due to its modular design and lower operating temperature. The economic advantage is attributed to the lower operation temperature (120 °C vs. 150 °C) and lower regeneration energy requirement (2.85 GJ/tonne CO2 vs. 4.25 GJ/tonne CO2). Maintaining a purge rate below 0.03 % is crucial for the solid sorbent's benefits over the MEA CCS process
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