To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Sound entering the ear is known not only to transmit signals to the nerve system, but also to generate vortex-like steady streaming in the cochlea. This streaming has been suggested as the primary vehicle for drug delivery in the inner ear (Sumner, Mestel & Reichenbach, 2021, Sci. Rep., vol. 11, 57). An alternative vehicle by pure diffusion alone has also been suggested by Sadreev et al. (2019, Front. Cell. Neurosci., vol. 13, 161). This paper purports to examine both mechanisms analytically, and compare their relative importance, based on the two-dimensional model of Allen (1977, Acoust. Soc. Am., vol. 61, 110–119). First, we reconstruct the fluid mechanics of the Békséy vortices by an asymptotic theory of multiple scales as a complement to the two-dimensional numerical theory of Edom, Obrist & Kleiser (2014, J. Fluid Mech., vol. 753, 254–278). For discerning the difference between Sumner, Mestel & Reichenbach (2021) and Sadreev et al. (2019), we combine sound-induced streaming and molecular diffusion by modeling the drug as a solute of known diffusivity. It will be shown that due to the high frequency of sound, advection is augmented by the Lagrangian velocity, but molecular diffusion still dominates drug transport in the cochlear duct, unlike Taylor dispersion of pollutant by tides in a shallow river.
This letter discusses the complex nature of plastics, why regulating plastics is a ‘wicked problem’, and the implications of a life cycle approach. The draft Global Plastics Treaty attempts to address two key problems: the cap on production and the problem of chemical additives in plastics. As a ‘wicked’ problem with many conflicting interests, dealing with plastics requires a holistic life cycle approach completely different from the Montreal Protocol. Strict and enforced limits on polymer production would reduce plastics pollution and also encourage a reduction in the range of additives, as limiting production would make mechanical or chemical recycling more viable. Used plastics need to be turned into a commodity rather than a waste, and reducing and standardising the number of different chemical formulations would help by reducing the number of chemicals to be regulated. To achieve these objectives, this letter argues for a regulatory approach based on a forensic analysis that applies extended environmental systems analysis to all the life cycle stages of the plastics value chain.
The future development of strategies with positive effects on urban livability and experience as climate change continues to evolve is the future challenge. The endeavor will continue to require the development of a range of priorities and strategies needed to achieve and sustain positive responses and outcomes. Much will depend on the vision and resources available to communities as climate change and the need for viable strategies continue to influence cur¬rent and future planning and design. The requisites acknowledge the evolv¬ing third phase of climate change, with its unknown extent of effects on urban livability and the current and future requirements communities may poten¬tially confront while attempting to establish sustainable outcomes for achiev¬ing equitable access, livability, and positive identity in the future. Inevitably, these and other factors will respond to the effects that climate change may have on the prospect of urban landscape contexts and the quality of future livability in cities and towns.
The degree of current and future challenges that communities are likely to experience in the immediate future could be sufficient enough to direct current efforts to produce strategies as environmental and cultural factors continue to evolve. The two prime concerns are equity and climate mitiga¬tion in urban contexts. The current expectations are based on immediate experiences and outcomes. The potential issues in future priorities and strate¬gies are the unknown factors relative to the climate models currently in use regarding present and future climate qualities.
Single-crystal synchrotron X-ray diffraction data were collected up to 10 GPa at room temperature on a natural omphacite with composition close to Jd43Di57, at the Xpress beamline at Elettra Synchrotron, using a diamond anvil cell. A second-order Birch-Murnaghan equation of state (EoS) fit to the unit-cell volumes determined at 20 pressure points yielded V0 = 422.85(15) Å3, and K0 = 121.3(1.2) GPa. These elastic parameters are consistent with the general trend of the diopside–jadeite join. The structural evolution with pressure was determined from both ab initio simulations and structure refinements to the X-ray intensity data. The consistency between experimental findings and local geometrical distortions identified through ab initio calculations is discussed. A distortion variation at the M1 polyhedron occurs at ∼3 GPa, which correlates with the TILT angle of the T2 tetrahedron which stabilises at a similar pressure, coinciding with a decrease in the rate of M1 deformation under pressure.
These results revealing the structural evolution with pressure correlate with changes observed previously in some Raman shifts in the same pressure range in the same material.
The current focus on the effects of climate change and the future quality of urban landscape access is evolving rapidly in many regions, locally and glob¬ally. With the need to produce positive strategies for the management of cli¬mate change and urban livability, cities and towns are articulating strategies focused on climate responses and equitable access as urban enhancements. Cities have begun to apply their strategies with the intention of producing outcomes that respond to climate and equity issues. Some communities rec¬ognized the climate and equity issues several years ago, while other com¬munities have more recently included climate change in their planning and design agendas. With the scientific estimate of climate change and its effects and the current need for regions to quickly respond to climate issues, many cities are committed to producing immediate priorities and potential strate¬gies for the benefit of future livability in their respective locations.
Urban Landscape Priorities, Strategies, and Prospect presents an investigation of urban priorities and strategies dedicated to climate change, including enhancements and equitable access in cities and towns. Three themes—time, resources, and livability—occur in the seven chapters. Time refers to cur-rent and future issues of climate change within the next 10 to 20 years, while resources include the support communities will need to maintain positive ecological and cultural responses to climate change. The quality of livability includes equitable access to enhancements as cities and towns respond to the current and future demands of climate change. Each theme ultimately reflects the goals and objectives of individual communities, including the require¬ments for maintaining livability within their urban settings. For example, community resources depend on economic factors and public support needed to effectively respond to unpredictable climate conditions from year to year.
Urban landscapes continue to be a prime element in the quality of livability and experience in city contexts. Since the earliest permanent settlements appeared in the Near East several thousands of years ago, urban landscapes have evolved as an interplay between physical and cultural factors and included viable responses to environmental conditions and cultural prefer¬ences. With effective responses to climate and equity issues, current cities and regions have opportunities to enhance livable urban contexts, including connections and places. The results would be cities with a range of urban landscapes available to a broader range of inhabitants, including residents in current under-enhanced locations. Current recommended standards for achieving positive results are a matter of community priorities and available resources in support of livability and are a function of climate mitigation and adaptation commitments, local and global.
Time, resources, and livability are three themes related to the potential prospect of urban landscapes in cities and towns. The three themes express the common points of focus for cities and towns as they attempt to begin responding to future climate change. The first theme is the quality of com¬munity responses to climate change in current and future urban landscapes, within a defined time frame. Until the recent climate events of 2023, responses to climate change were essentially the production of climate action plans and heat action plans for cities and towns to eventually utilize during current and future climate change. Actual physical and cultural responses to the recent plans are yet to occur in many community locations, though some cities and towns have made the effort to begin producing adaptations to mitigate local climate change.
The intention of the third and fourth chapters of the text is the articula¬tion of the future quality of planning and design outcomes relative to the climate change strategies and resources cities and towns are attempting to achieve within the current decade and beyond. The content represents the first phase of climate change and its transition into the second and third phases of urban responses to climate effects. Communities have managed to function during the first and second phases of climate change from 2000 to the extreme climate events beginning in 2021. Now, communities are in the beginning of the transition to the third phase of climate change in urban contexts, with distinct requirements for urban strategies and enhancements for providing equitable access and livability. The strategies consist of the application of positive climate change alternatives, includ¬ing the use of existing bottom-up ecological and cultural qualities, with the potential to preserve and enhance urban locations for the benefit of the livability within the contexts of current and future urban landscapes. The challenge for communities is to utilize sustainable strategies with the potential to enhance the existing and future quality of their respective urban contexts, including urban connections and landscapes. At best, the outcomes would be for the benefit of all residents within the contexts of existing cities and towns.
The potential outcomes related to sustaining outcomes in urban contexts, including urban landscape connections and places, will include applying concepts to urban landscapes in communities with the potential to estab¬lish long-term, sustainable enhancements in their urban contexts. Currently, communities are attempting to utilize existing, bottom-up urban qualities as sources for sustainable urban enhancements with the potential for function¬ing in the long-term existence of cities and towns.
Current and Future Priorities, Strategies, and Opportunities
At this point, the progress that cities and towns have accomplished regards priorities and strategies related to urban livability and identity. The focus has included references to climate action sources that have defined urban land¬scapes and their value to communities. To some extent, much of what has been accomplished up to the present time is a summary of the challenges and accomplishments that have made many cities livable, though still in need of specific improvements, including equitable access to urban amenities. Since 2022, climate change has evolved into a third phase with its severe quality of intense heat and storms. While the third phase of climate change progresses in response to 2030 climate standards, many cities and towns have pro¬duced heat action plans, in addition to their existing general climate action plans. Such efforts define the third phase of this text with its emphasis on the future of climate change and its potential effect on urban contexts. The focus includes current strategies for enabling equitable access to enhanced urban landscape connections and places in underrepresented urban locations.
The synthesis of ecology and culture in current and future community climate strategies and outcomes is a source for evaluating current planning and design applications and is the focus of this chapter. The issue of climate change and the existing need for enhanced equity includes the opportunities for the enhancement of underrepresented contexts. By providing individuals with the opportunity to connect to urban places with a level of refinement, walkability, livability, and identity, their contribution to the quality of experi¬ence in urban contexts becomes an equitable accomplishment.
The focus on specific urban landscape strategies pertinent to livability, equity, and experience during the current and future presence of climate change has been a prime interest during the past several decades. Multiple factors pro¬vide the stage for urban landscapes to advance equitable access and climate mitigation as contributors to levels of experience. From initial impressions to refined aesthetic experience, the quality and location of the fundamental experiential process provide references for the existence and significance of opportunities to connect with nature in urban contexts. Perception, interpre¬tation, and response are included in the quality of such experience and pro¬vide levels of individual interaction with nature. The experience confirms the value of urban factors with the quality to generate interest in urban contexts at a level to produce notable individual experience. The future challenge is the presence of effective climate mitigation strategies and equitable access to nature as livability and experiential influences.
Access and connection to nature derive from the lengthy period of human pre-settlement until the appearance of the Agricultural Revolution. During that time, humans managed to survive by way of hunting and gathering through the seasons. By at least fifteen thousand years ago, with the warming of the planet and the increase in human populations in the Near East, perma¬nent settlements began to appear throughout the region. Our long-term inter¬action with nature continues to support the presence of nature in urban and suburban contexts as a health resource. Since the appearance of permanent settlements, formal gardens and green street enhancements have appeared in many settlements, though access to such amenities was variable over time.
Synthetic-aperture radar images and mesoscale models show that wind-farm wakes differ from single-turbine wakes. For instance, wind-farm wakes often narrow and do not disperse over long distances, contrasting the broader and more dissipating wakes of individual turbines. In this work, we aim to better understand the mechanisms that govern wind-farm wake behaviour and recovery. Hence we study the wake properties of a $1.6$ GW wind farm operating in conventionally neutral boundary layers with capping-inversion heights $203$, $319$, $507$ and $1001$ m. In shallow boundary layers, we find strong flow decelerations that reduce the Coriolis force magnitude, leading to an anticlockwise wake deflection in the Northern Hemisphere. In deep boundary layers, the vertical turbulent entrainment of momentum adds clockwise-turning flow from aloft into the wake region, leading to a faster recovery rate and a clockwise wake deflection. To estimate the wake properties, we propose a simple function to fit the velocity magnitude profiles along the spanwise direction. In the vertical direction, the wake spreads up to the capping-inversion height, which significantly limits vertical wake development in shallow-boundary-layer cases. In the horizontal direction and for shallow boundary layers, the wake behaves as two distinct mixing layers located at the lateral wake edges, which expand and turn towards their low-velocity side, causing the wake to narrow along the streamwise direction. A detailed analysis of the momentum budget reveals that in deep boundary layers, the wake is predominantly replenished through turbulent vertical entrainment. Conversely, in shallow boundary layers, wakes are mostly replenished by mean flow advection in the spanwise direction.
Bubble–particle collisions in turbulence are key to the froth flotation process that is widely employed industrially to separate hydrophobic from hydrophilic materials. In our previous study (Chan et al., 2023 J. Fluid Mech.959, A6), we elucidated the collision mechanisms and critically reviewed the collision models in the no-gravity limit. In reality, gravity may play a role since, ultimately, separation is achieved through buoyancy-induced rising of the bubbles. This effect has been included in several collision models, which have remained without a proper validation thus far due to a scarcity of available data. We therefore conduct direct numerical simulations of bubbles and particles in homogeneous isotropic turbulence with various Stokes, Froude and Reynolds numbers, and particle density ratios using the point-particle approximation. Generally, turbulence enhances the collision rate compared with the pure relative settling case by increasing the collision velocity. Surprisingly, however, for certain parameters the collision rate is lower with turbulence compared with without, independent of the history force. This is due to turbulence-induced bubble–particle spatial segregation, which is most prevalent at weak relative gravity and decreases as gravitational effects become more dominant, and reduced bubble slip velocity in turbulence. The existing bubble–particle collision models only qualitatively capture the trends in our numerical data. To improve on this, we extend the model by Dodin & Elperin (2002 Phys. Fluids14, 2921–2924) to the bubble–particle case and found excellent quantitative agreement for small Stokes numbers when the history force is negligible and segregation is accounted for.
A prime opportunity for cities and towns is the potential to utilize existing local urban landscape qualities as sources for the enhancement of landscape connections and places. The application of this opportunity is often a key fac¬tor in the preservation of livability and identity in their respective urban loca¬tions. The application of potential bottom-up enhancements is a prime focus for many communities interested in the role and use of existing inductive bot¬tom-up context qualities as priorities for enhanced livability and community identity. Bottom-up responses to urban context enhancements are a focus in this discussion, with references to the three themes of the text, including time, resources, and livability. The discussion recognizes the role that bottom-up strategies play in the enhancement of connections and places, emphasizing the opportunity for the use of bottom-up planning and design strategies in urban landscapes. However, the broader issue is the need for equitable access to urban landscape enhancements within underrepresented urban locations.
Within the past decade, bottom-up preferences and strategies have contin¬ued to evolve as resources in line with the need to provide equitable access to urban landscape qualities. Urban locations with historical significance, unique scale, materials, and efficient connection are examples of bottom-up opportunities for the preservation of identity and livability in urban contexts that are sustaining enhancements in response to current and future climate change. The significant difference concerns what communities have so far been able to produce in terms of livable and equitable landscape contexts and what communities may be able to accomplish in the future. Both rest on being able to endure current and future climate change and maintain via¬ble livability strategies.
Plastic chemicals are numerous and ubiquitous in modern life and pose significant risks to human health. Observational epidemiological studies have been instrumental in identifying consistent and statistically significant associations between exposure to certain chemicals and adverse health outcomes. However, these studies often fail to establish causality due to the complexity of real-world chemical mixtures, confounding factors, reverse causation, and study designs that lack measures reflecting underlying genetic and cellular mechanisms indicating causal pathways to harm. Addressing these limitations requires moving beyond traditional ‘black-box’ epidemiology, which mainly focuses on the strength of associations. We propose adopting hybrid epidemiological methodologies that incorporate genetic susceptibility and molecular mechanisms to uncover biological pathways, combined with machine learning and statistical analysis of chemical mixtures, to strengthen the causal evidence linking exposure to harm. By integrating observational multi-omics data with experimental and mechanistic models, hybrid epidemiology offers a transformative path to improve causal evidence and public health interventions. In addition, machine learning and statistical methods provide a more nuanced understanding of the health effects of exposures to plastic chemical mixtures, facilitating the identification of interactions within chemical mixtures and the influence of biological pathways. This paradigm shift is critical addressing the complex challenges of plastic exposure and protecting human health.
Iron oxide-apatite (IOA) deposits and the related iron oxide-copper-gold (IOCG) deposits, are major repositories of base metals (Fe, Cu). However, the genesis of IOA deposits remains a topic of debate, with both magmatic and hydrothermal models. Close parallels exist between IOA deposits and some skarns, which exhibit sodic alteration in silicic host rocks, but are unequivocally metasomatic in origin. In this study we compared the trace element composition of magnetite from IOA deposits in the Kiruna District, Sweden, with magnetite skarns from the Turgai district, Kazakhstan. Comparison with published discrimination diagrams for deposit types shows poor correspondence with defined fields. The two districts correspond closely in terms of Sn and Ga contents, with close correspondence to previous analyses of porphyry and skarn deposits. When estimates of temperature (T) from Mg in magnetite are considered Sn and Ga show little correlation with T, whereas Ni increases and Mn decreases with decreasing T. Rare earth element distribution patterns correspond to local igneous rocks, albeit at lower absolute concentration. Tin and Ga, as high valence ions in tetrahedral sites in magnetite are potentially more resistant to re-equilibration and preserve a high temperature magmatic-hydrothermal signature comparable to Fe skarns and the early magmatic stages of some IOA deposits in the Kiruna district. Overall, these data are consistent with an early high-temperature mineralisation stage, potentially resulting from hypersaline brines or salt melts interacting with volcanic rocks (Kiruna district) or limestone and volcanic rocks (Turgai district), followed by subsequent hydrothermal magnetite mineralisation to relative low T. The high-temperature stage is better represented in the Turgai skarns compared to the Kiruna district IOA deposits. Overprint of sulfide mineralisation on magnetite results in an increase in Ni content which may be an effective tracer for IOCG mineralisation related to IOA deposits, or sulfide mineralisation in skarns, whilst metamorphism may homogenise and reduce trace element concentrations.
Characterizing the structure and composition of clay minerals on the surface of Mars is important for reconstructing past aqueous processes and environments. Data from the CheMin X-ray diffraction (XRD) instrument on the Mars Science Laboratory Curiosity rover demonstrate a ubiquitous presence of collapsed smectite (basal spacing of 10 Å) in ~3.6-billion-year-old lacustrine mudstone in Gale crater, except for expanded smectite (basal spacing of 13.5 Å) at the base of the stratigraphic section in a location called Yellowknife Bay. Hypotheses to explain expanded smectite include partial chloritization by Mg(OH)2 or solvation-shell H2O molecules associated with interlayer Mg2+. The objective of this work is to test these hypotheses by measuring partially chloritized and Mg-saturated smectite using laboratory instruments that are analogous to those on Mars rovers and orbiters. This work presents Mars-analog XRD, evolved gas analysis (EGA), and visible/shortwave-infrared (VSWIR) data from three smectite standards that were Mg-saturated and partially and fully chloritized with Mg(OH)2. Laboratory data are compared with XRD and EGA data collected from Yellowknife Bay by the Curiosity rover to examine whether the expanded smectite can be explained by partial chloritization and what this implies about the diagenetic history of Gale crater. Spectral signatures of partial chloritization by hydroxy-Mg are investigated that may allow the identification of partially chloritized smectite in Martian VSWIR reflectance spectra collected from orbit or in situ by the SuperCam instrument suite on the Mars 2020 Perseverance rover. Laboratory XRD and EGA data of partially chloritized saponite are consistent with data collected from Curiosity. The presence of partially chloritized (with Mg(OH)2) saponite in Gale crater suggests brief interactions between diagenetic alkaline Mg2+-bearing fluids and some of the mudstone exposed at Yellowknife Bay, but not in other parts of the stratigraphic section. The location of Yellowknife Bay at the base of the stratigraphic section may explain the presence of alkaline Mg2+-bearing fluids here but not in other areas of Gale crater investigated by Curiosity. Early diagenetic fluids may have had a sufficiently long residence time in a closed system to equilibrate with basaltic minerals, creating an elevated pH, whereas diagenetic environments higher in the section may have been in an open system, therefore preventing fluid pH from becoming alkaline.
The rare Pb silicate jagoite, known only from the Långban and Pajsberg Mn–Fe oxide deposits in Värmland, Sweden, is associated with a more diverse mineral assemblage than originally described: alamosite, barysilite, hyttsjöite, margarosanite, melanotekite, nasonite and yangite and other, not fully characterised Pb silicates. Primary melanotekite and barysilite, formed as skarn (together with hematite, quartz, clinopyroxene and andradite) during regional metamorphism, are prone to alteration, with Cl⁻, SiO₂, Ca2⁺ and H₂O acting as modifying agents. In the process, newly formed Pb silicates exhibit increasing Si content, reflecting a higher degree of SiO₄ polymerisation at high pH and decreasing temperatures.
A refinement of the crystal structure of jagoite from X-ray diffraction data, to R1 = 1.2% [space group P$\bar 6$2c, a = 8.53926(5) Å and c = 33.3399(2) Å], confirms previous work, and provides significantly improved structural parameters. New data were also obtained with Mössbauer spectroscopy, laser-Raman micro-spectroscopy, electron-microprobe and laser-ablation inductively coupled plasma mass spectrometry analyses. The results indicate that jagoite accommodates minor elements, notably Al at an octahedrally coordinated Fe-dominated site and Mn3⁺, Zn and Mg at four-coordinated mixed Fe–Si sites, and small amounts of Ca+Na replacing Pb. Jagoite is also enriched in Be, Sb, Bi and Br, but those elements have a limited role in its crystal chemistry. Mössbauer measurements show that Fe3⁺ is distributed over three different crystallographic sites, two 4-coordinated and one 6-coordinated, and that jagoite remains paramagnetic down to 77 K. The ideal chemical formula for jagoite should be written Pb11Fe5Si12O41Cl3 for Z = 2.
Ice crystal fabrics can exert significant rheological control on ice sheets and ice shelves, potentially softening or hardening anisotropic ice by several orders of magnitude compared to isotropic ice. We introduce an anisotropic extension of the Shallow Shelf Approximation (SSA), allowing for fabric-induced viscous anisotropy to affect the flow of ice shelves in coupled, transient simulations. We show that the viscous anisotropy of synthetic ice shelves can be parameterized using an isotropic flow enhancement factor, suggesting that existing SSA flow models could, with little effort, approximate the effect of fabric on flow. Next, we propose a new way to directly solve for SSA fabric fields using satellite-derived velocities, assuming velocities are approximately steady and that fabric evolution is dominated by lattice rotation with or without discontinuous dynamic recrystallization. We apply our method to the Ross and Pine Island ice shelves, Antarctica, suggesting that these regions might experience significant fabric-induced hardening and softening depending on the relative strength of lattice rotation and recrystallization. Our results emphasize the ice-dynamical relevance of needing to better constrain the strength of fabric processes. This calls for more widespread fabric and temperature measurements from the field, since measurements are currently too sparse for model validation.