Pre-existing Layer Research Articles

A possible role of e-FAST in the hemodynamically stable polytrauma patient: results of a single trauma center preliminary restrospective study.

The purpose of this work is to evaluate whether EFAST can also play a role in the hemodynamically stable polytrauma patient, without delaying his arrival in the CT-scan room. In a period of seven month, 748 polytrauma patients were retrospective valued; we analyzed the findings of the CT exams of 485 haemodynamically stable patients for whom the EFAST investigation was not requested, highlighting the possible presence of findings that, if reported during the EFAST, could have changed the patient management. 52 hemodynamically stable patients with CT examination findings potentially detectable by ultrasound examination directly in the shock room, which represent a percentage of about 11% of all the hemodynamically stable patients analyzed; about 54% of CT findings are represented by the presence of pneumothorax. Looking to the results and the sensitivity of thoracic ultrasound in identifying even small flaps of pneumothorax, the evaluation by EFAST ultrasound examination could be extended at least to all those patients with chest trauma or who require endotracheal intubation. The risk of generating a hypertensive pneumothorax following positive pressure intubation is widely known, and certainly the presence of a pre-existing layer of pneumothorax, even if of modest entity, further increases this possibility.

Peridynamics-based model of composite lamina with progressive variations in mechanical properties

An analytical model of the fiber-reinforced composite lamina is constructed based on bond-based peridynamics (PD), which utilizes variable matrix bonds and fiber bonds to evaluate the static properties of matrix and fiber materials, respectively. The bond stiffness of the matrix is determined by trigonometric functions, and fibers are represented by constants. The proposed PD model describes the continuous variations in the static properties of composites as a function of fiber angle. Both the conventional analytical method and the PD method are used to solve the failure-free elastic deformation issue. The two methods estimate maximum errors in the displacement of material points in the x and y directions of 0.01 % and 4.86 %, respectively, indicating good consistency. The failure propagation of the preexisting crack layer under the axial tensile load is simulated and the obtained failure modes are in good agreement with experimental results. The proposed composite lamina model simulates the influence of fiber direction on overall behavior through various matrix bond stiffness. Breaking through the limitation of constant matrix bond stiffness in conventional models, is conducive to promoting the further development of bond-based composite PD models.

Formation mechanism and structural evolution of recumbent fold nappes: New insights from the bizerte area, northern Tunisia

The structural analysis of the Bizerte area in northern Tunisia, utilizing well data and field observations, reveals a complex arrangement of fold structures characterized by recumbent fold nappes to local sheath-like fold structures, indicative of a deep detachment phenomenon. The genesis and present geometry of these fold structures unravel a multifaceted structural history: (i) In the Tortonian folding phase, a detachment mechanism may have initiated the formation of a horizontal shearing plane at the base of the Paleocene marls. The gradual evolution of syn-shear recumbent fold nappes into sheath folds within sedimentary to pseudo-metamorphic rocks is attributed to a flow perturbation process analogue to “layer-parallel shearing,” dictating the geometric configuration of folds subsequent to a simple shear inducing perturbations in pre-existing layer disturbances. (ii) During the Late Quaternary shortening phase, a NW-trending right lateral shear zone emerged, delineated by the reactivation of pre-existing faults under compression. The reorientation of the anterior fold axes is attributed to the counterclockwise rotation of rigid blocks within the framework of P-type conjugate fractures. (iii) The transition to thin-skinned tectonics, characterized by the uplift of previously buried material, was characterized by a significant increase in shortening during Neogene events, encompassed in the broader regional geodynamic context of continental collision. From the Lower Quaternary onward, the structural model exhibits a combination of layer-parallel and layer-normal shear processes.

Evidence for layered anisotropic stratified turbulence in a freely evolving horizontal shear flow

We present evidence for layered anisotropic stratified turbulence (LAST) and mixing produced in a freely evolving uniformly stratified shear layer where the direction of shear is orthogonal to gravity. As originally reported by Basak & Sarkar (J. Fluid. Mech., vol. 568, 2006, pp. 19–54), such a flow develops a rich three-dimensional structure in the form of interlocking columnar vortices formed by horizontal shear instability that remain coherent at large scales due to the stabilising vertical stratification. Here, we modify the initial velocity field by introducing additional small-amplitude vertical perturbations designed to be representative of pre-existing horizontal layers often observed in strongly stratified ocean environments. This reveals a novel finite amplitude, non-normal mode growth mechanism through which the vertical shear between layers may be rapidly amplified by its interaction with the horizontal shear layer prior to the growth of shear instability, leading to a rapid turbulent transition instigated by the subsequent interaction of the layers with the emerging columnar vortices. Through a consideration of relevant flow statistics and associated dimensionless parameters, we demonstrate that turbulence can enter the LAST regime, thereby indicating a generic mechanism leading to the transient development of regions of strongly stratified turbulence in the ocean. We discuss the properties of mixing and the parameterisation of mixing efficiency in terms of the relationship between turbulent length scales in the flow, in particular highlighting links to models based on the classical vertical shear instability paradigm typically associated with more weakly stratified flows that produce isolated turbulent ‘patches’.

Effects of Gas Layer Thickness on Capillary Interactions at Superhydrophobic Surfaces.

Strongly attractive forces act between superhydrophobic surfaces across water due to the formation of a bridging gas capillary. Upon separation, the attraction can range up to tens of micrometers as the gas capillary grows, while gas molecules accumulate in the capillary. We argue that most of these molecules come from the pre-existing gaseous layer found at and within the superhydrophobic coating. In this study, we investigate how the capillary size and the resulting capillary forces are affected by the thickness of the gaseous layer. To this end, we prepared superhydrophobic coatings with different thicknesses by utilizing different numbers of coating cycles of a liquid flame spraying technique. Laser scanning confocal microscopy confirmed an increase in gas layer thickness with an increasing number of coating cycles. Force measurements between such coatings and a hydrophobic colloidal probe revealed attractive forces caused by bridging gas capillaries, and both the capillary size and the range of attraction increased with increasing thickness of the pre-existing gas layer. Hence, our data suggest that the amount of available gas at and in the superhydrophobic coating determines the force range and capillary growth.

The Tennis Ball Marker in the south-eastern Bushveld Complex: comparison with the Boulder Bed of the Western Bushveld Complex and proposed genesis by disaggregation of intrusive sills in processes akin to those involved in the formation of peperites and mafic enclave swarms

Abstract The Tennis Ball Marker (TBM) is a distinctive lithology that is particularly well developed near the base of the Rustenburg Layered Suite (RLS) on the farm Middelkraal 221 JS, approximately 20 km south of the town of Roossenekal in the Eastern Limb of the Bushveld Complex. The name refers to a texture in which approximately tennis ball-sized spheroidal aggregates of feldspathic orthopyroxenite or melanorite occur within a lighter-coloured gabbronorite host rock. We have identified two well-defined layers in which pyroxenitic spheroids are densely packed, with spheroids more sparsely distributed elsewhere in the host gabbronorite. The TBM at Middelkraal has previously been described as a contact phenomenon where the Main Zone (MZ) has been contaminated by footwall lithologies that include basaltic lavas of the Dullstroom Formation. Our geochemical data, in tandem with new geological mapping, suggest that the TBM is in fact hosted by the Marginal Sill Phase (MSP), and not by the MZ. The MSP is a regional feature that separates the overlying units of the RLS from its floor rocks throughout this region. Sills that make up the MSP were injected on a regional plane of weakness in the primary stratigraphy prior to the intrusion of the remainder of the RLS. The MSP does not represent the chilled carapace of a magma chamber, as implied in previous studies, and there is no evidence of a genetic relationship with the MZ. Our geochemical data indicate, furthermore, that the gabbronorite constituting the dominant lithology of the MSP that hosts the TBM at Middelkraal formed from a sequence of several magma influxes. The TBM is ascribed to one or more subsequent intrusions of pyroxenitic magma into the still hot gabbronoritic host sequence. There are no comparable lithologies reported from other layered intrusions, and the closest analogy to the TBM is the Boulder Bed in the Upper Critical Zone (UCZ) of the Western Bushveld Complex, which has received considerably more attention in the literature than has the TBM. The Boulder Bed has been ascribed variously to in-situ agglomeration of clusters of orthopyroxene resulting from liquid immiscibility, in situ breakup of a pre-existing pyroxenite layer, possibly due to seismic events, or the disaggregation of a late-stage pyroxenitic sill intruding into the magma chamber. We subscribe to the latter mechanism for both the TBM and the Boulder Bed, drawing on similarities with mafic magmatic enclaves, where mafic sills have been shown to have disaggregated on intrusion into earlier bodies of felsic to intermediate igneous rock, or peperites, where magma intruded fluidised sediments.

Prediction of thermal conduction in a four-phase composite with lowly-conducting interfaces based on variational asymptotic method

Due to the complex physical and chemical reactions, surface contamination and debonding, the interfaces within the four-phase composite, represented by hollow-glass-bead reinforced cement based material (HGB-CBM), cannot be assumed to be perfect. In order to consider the effect of imperfect interfaces, a novel thermal conduct model is developed. An imperfect interface is used to replace the pre-existing transition layer in the composite material, and the discontinuous temperature field proportional to the normal heat flow is preserved by using Hadamard’s relation and Taylor’s expansion. Based on the principle of minimum functional and variational asymptotic method, the governing variational statement for thermal conduct model is derived, and validated through comparison with RVE-based FEM and experimental results. It can be concluded that HGB-CBM with lowly-conducting imperfect interfaces has lower effective thermal conductivity, smaller heat flux within HGB and more significant changes at imperfect interfaces, which may be due to longer and more complex heat flux paths along the imperfect interfaces. HGB-CBM with larger volume fraction of HGB and smaller thermal conductivity of bead wall can provide better thermal insulation effect, which could provide reference for using HGB-CBM as thermal-insulating material in building engineering.

Amelioration of 2D hybrid architecture for protective surface using thiourea-based inhibitor: Electrochemical and computational perspectives

The coexistence of inorganic and organic substances is desirable for protecting metallic materials from corrosive environments. Nonetheless, the interaction and in situ formation mechanism of 2D hybrid architectures have not been reported. For this purpose, three distinctive thiourea-based (TB) compounds (namely, thiourea (TU), 1-phenylthiourea (PTU), and 1,3-diphenyl-2-thiourea (DPTU)) were used as organic inhibitors to understand how the chemical structure of the inhibitors affected their interaction with the porous inorganic layer. The TB compounds were used to control the corrosion kinetics by adding inhibitors into corrosive environments that interact readily with the pre-existing inorganic layer fabricated by plasma electrolysis oxidation (PEO). This resulted in a hybrid layer because the TB compounds were actively adsorbed onto the inorganic layer, thereby sealing the defects effectively. The heteroatom adjacent to the thiourea sites were the primary sites for bonding with the inorganic layer. Moreover, the presence of a benzene ring considerably increased the feasible adsorption patterns. The increment in chemical reactivity during adsorption permitted more interaction with the Cl− ions from a corrosive environment to form a 2D hybrid layer through complex coordination. This layer showed an improvement in corrosion performance. Furthermore, the computational perspectives effectively explained the adsorption and interfacial reaction of the 2D hybrid layer with the inorganic layer and reinforce the correlation with the experimental observations.

In-situ construction of grass-like hybrid architecture responsible for extraordinary corrosion performance: Experimental and theoretical approach

Despite the engineering potential by the co-existence of inorganic and organic substances to protect vulnerable metallic materials from corrosive environments, both their interaction and in-situ formation mechanism to induce the nature-inspired composite remained less understood. The present work used three distinctive mercapto-benzazole (MB) compounds working as corrosion inhibitors, such as 2-mercaptobenzoxazole (MBO), 2-mercaptobenzothiazole (MBT), and 2-mercaptobenzimidazole (MBI) in a bid to understand how the geometrical structure arising from O, S, and N atoms affected the interaction toward inorganic layer. MB compounds that were used here to control the corrosion kinetics would be interacted readily with the pre-existing MgO layer fabricated by plasma electrolysis. This phenomenon triggered the nucleation of the root network since MB compounds were seen to be adsorbed actively on the defective surface through the active sites in MB compound. Then, the molecule with twin donor atoms adjacent to the mercapto-sites affected the facile growth of the grass-like structures with ‘uniform’ distribution via molecular self-assembly, which showed better corrosion performance than those with having dissimilar donor atoms with the inhibition efficiency (η) of 97% approximately. The formation mechanism underlying nucleation and growth behavior of MB molecule was discussed concerning the theoretical calculation of density functional theory.

Spontaneous local redox reaction to passivate CNTs as lightweight current collector for high energy density lithium ion batteries

Extensive usage of highly conductive carbon materials with large specific surface area (e.g., carbon nanotubes, CNTs) in lithium ion batteries (LIBs), especially as current collector of anodes, suffers from low initial coulombic efficiency (ICE), large interfacial resistance, and severe embrittlement, as the large specific surface area often results in severe interfacial decomposition of the electrolyte and the formation of thick and fluffy solid electrolyte interphase (SEI) during cycling of LIBs. Herein, we demonstrate that when the CNT-based current collector and Na foil (which are being stacked intimately upon each other) are being placed in Na+-based organic electrolyte, local redox reaction between the Na foil and the electrolyte would occur spontaneously, generating a thin and homogeneous NaF-based passivating layer on the CNTs. More importantly, we found that owing to the weak solvation behaviors of Na+ in the organic electrolyte, the resulting passivation layer, which is rich in NaF, is thin and dense; when used as the anode current collector in LIBs, the pre-existing passivating layer can function effectively in isolating the anode from the solvated Li+, thus suppressing the formation of bulky SEI and the destructive intercalation of solvated Li+. The relevant half-cell (graphite as anode) exhibits a high ICE of 92.1%; the relevant pouch cell with thus passivated CNT film as current collectors for both electrodes (LiCoO2 as cathode, graphite as anode) displays a high energy density of 255 Wh kg−1, spelling an increase of 50% compared with that using the conventional metal current collectors.

Multilayer graphene sunk growth on Cu(111) surface

The controllable growth of multilayer graphene is a challenging research topic. Prior results show graphene adlayers can grow beneath pre-existing graphene layers on a Cu(111). The conventional inverted-wedding-cake (IWC) model used to describe this incurs an energy disadvantage due to deformation in the overlying graphene. We propose an alternative theoretical model, the sunk growth mode, for understanding multilayer graphene growth on Cu substrates. Extensive density functional theory (DFT) calculations show that multilayer graphene grown via this sunk mode is energetically favourable compared to the on-terrace growth mode for Cu(111). These results reveal that graphene underlayers tend to grow in a sunk growth mode, minimizing deformation in the overlayers, reducing deformation energy. Further density functional tight binding-molecular dynamic (DFTB-MD) simulations on Cu(111) substrates yield sunken structures consistent with our sunk growth mode. Moreover, AFM investigations of experimentally grown multilayer graphene on polycrystaline Cu show that while friction data indicates multiple graphene edges in the sample, the topological height measurement indicates flat graphitic sheets, further confirming our sunk growth mode. This discovery provides a novel and more reasonable model for the “underlayer” growth of multilayer graphene and can be extended to a general theory for the multilayer graphene growth on various substrates.

Fluidisation of yield stress fluids under vibration

<h2>Abstract</h2> Motivated by the industrial processing of chocolate, we study experimentally the fluidisation of a sessile drop of yield-stress fluid on a pre-existing layer of the same fluid under vertical sinusoidal oscillations. We compare the behaviours of molten chocolate and Carbopol which are both shear-thinning with a similar yield stress but exhibit very different elastic properties. We find that these materials spread when the forcing acceleration exceeds the same threshold which is determined by the initial deposition process. However, the height reduction due to spreading is typically at least three times greater in chocolate than in Carbopol under similar forcing. Moreover, the two materials exhibit very different spreading behaviours: whereas chocolate exhibits slow long-term spreading, the Carbopol drop rapidly relaxes its stress by spreading to a new equilibrium shape with an enlarged footprint. This spreading is insensitive to the history of the forcing. In addition, the Carbopol drop performs large-amplitude oscillations with the forcing frequency, both above and below the threshold. We investigate these viscoelastic oscillations and provide evidence of complex nonlinear viscoelastic behaviour in the vicinity of the spreading threshold. In fact, for forcing accelerations greater than the spreading threshold, our drop automatically adjusts its shape to remain at the yield stress. We discuss how our vibrated-drop experiment offers a new and powerful approach to probing the yield transition in elastoviscoplastic fluids.

Phase change in GeTe/Sb2Te3 superlattices: Formation of the vacancy-ordered metastable cubic structure via Ge migration

Interfacial phase-change memory (iPCM), comprising alternating layers of two chalcogenide-based phase-change materials—Sb2Te3 (ST) and GeTe (GT)—has demonstrated outstanding performance in resistive memories. However, its comprehensive understanding is controversial. Herein, the phase-change characteristic of iPCM is identified using atomic scale imaging, X-ray diffraction, and chemical analysis with first-principles density functional theory (DFT) calculations. By inducing laser pulsing, the ST/GT superlattice structure in the low-resistance state tends to reversibly convert into the modified metastable face-centered cubic (fcc) GeSbTe structure in the high-resistance state. This transition is driven by Ge atom rearrangement to pre-existing vacancy layers and ordered vacancy-layer formation. DFT atomistic modeling shows that the resistance difference of 102 orders between low- and high-resistance states is a direct consequence of the intercalation of Ge atoms into the vacancy layer. These results provide insights into iPCM phase-change mechanisms and phase-change random access memory design with low energy and high speed.

Influence of asphalt thickness on performance of geosynthetic-reinforced asphalt: Full-scale field study

In this study, a series of controlled traffic loadings was conducted on unreinforced and geosynthetic-reinforced full-scale asphalt overlays. Unlike the common objective of using paving interlayers to mitigate the development of reflective cracks, the main purpose of adopting geosynthetics for this study was to render an increased roadway structural capacity. The project involved instrumented test sections constructed during the rehabilitation of an in-service roadway in Texas, USA. The rehabilitation involved repairing the pre-existing pavement, placing tack coat, installing a geosynthetic interlayer (except in the unreinforced section), and finally constructing a 75 mm-thick asphalt overlay. This overlay comprised a 50 mm-thick, dense-graded (TY-D) layer overlain by a 25 mm-thick, thin-overlay mixture (TOM) layer. Controlled traffic loadings were conducted, which involved driving standard and light axle loads directly above asphalt strain gauges that had been installed at mid-depth of the pre-existing asphalt layer. Comparison of tensile strains among the different test sections revealed significantly smaller tensile strains in the geosynthetic-reinforced sections compared to those obtained in the unreinforced section. Consequently, and even though geosynthetic interlayers have often been adopted to minimize reflective cracking in asphalt overlays, the field monitoring results generated in this study demonstrate that they also provide added roadway structural capacity.

Mechanisms of corneal intrastromal laser dissection for refractive surgery: ultra-high-speed photographic investigation at up to 50 million frames per second.

Every year, more than a million refractive eye surgeries using femtosecond lasers are performed but the intrastromal cutting process remains an area of development. We investigated the mechanisms of laser dissection in cornea by ultra-high-speed photography. We found that the intrastromal bubble forms multiple lobes along the elongated laser plasma and the overlying lobes expand along the corneal lamellae. Videography demonstrated that the cutting process relies on crack propagation in the stroma along the bubble lobes with the crack originating from the pre-existing bubble layer. These insights are important for further improvement of the cutting mechanisms in refractive surgery.

Reduced cytotoxicity of nanomaterials driven by nano-bio interactions: Case study of single protein coronas enveloping polymersomes

The protein adsorption onto poly(acrylic acid)-block-polystyrene (PAA22-b-PS144) polymersomes has been investigated with regard to structural features, thermodynamic aspects and biological consequences. The light scattering measurements revealed the formation of protein coronas enveloping the polymeric capsules regardless of the chemical nature of the biomacromolecules. The experiments were conducted by using lysozyme, immunoglobulin G - IgG and bovine serum albumin - BSA as model proteins due to their differences concerning size and residual surface charge at physiological pH. The protein adsorption was further confirmed by isothermal titration calorimetry, and the experimental data suggest that the phenomenon is mainly governed by hydrogen bonding and van der Waals interactions. The pre-existing protein layer via the pre-incubation in protein environments notably attenuates the cytotoxicity of the nanomaterial compared to the pristine counterparts. This approach can possibly be extended to different types of assemblies when intermolecular interactions are able to induce protein adsorption and the development of protein coronas around nanoparticles. Such fairly simple method may be convenient to engineer safer nanomaterials towards a variety of biomedical applications when the nanotoxicity is an issue. Additionally, the strategy can possibly be used to tailor the surface properties of nanoparticles by adsorbing specific proteins for targeting purposes.

Effect of surface oxidation on the cesium chemisorption behavior of SS 304, Inconel 600 and X-750

ABSTRACT Cs chemisorption of structural materials is important for evaluating source terms. Stainless steels and Ni-based alloys utilized in light water reactors, exhibit similar oxidation films during normal operation. However, the presence of minor elements and temperature changes during accidents can alter surface structures and Cs chemisorption characteristics. The oxidation effects of three materials used in modern nuclear power plants were compared. Specimens with different pre-oxide films were prepared from well-polished SS 304, Inconel 600, and X-750, which were then coated with CsOH and treated at 300–1050 ᵒC. They were soaked in water after analysis to remove CsOH residues. CsOH residues, including Cs2FeO4 and Cs2CrO4, dominated pre-soaked specimens, with higher concentrations in the oxidized specimens, but disappeared after soaking. Some Cs particles enriched with Ti, Al, and Si were retained in post-soaked specimens. Cs, Si, and O enrichment between outer and inner oxide layers was detected from cross-sectional observations with larger Cs amount on SS 304, while lesser Cs which is also related to Ti located in the thinner outer layer of Inconel 600 and X-750. Cs enrichment on the inner layers is likely to form on the pre-existing layer and then overlap with the outer oxide layer growth.

Influence of a pre-existing glaze layer on the fretting-wear response of HS25 cobalt-based alloy subjected to various temperature conditions

The wear behavior of metallic alloys at variable temperature is a crucial aspect in many industrial components such as turbines and compressors in aircraft engines. In particular, the blade/disk contact is subjected to a cyclic thermal loading combined with a cyclic sliding (fretting) which can significantly damage the interface. The objective of this work is to investigate the behavior of the interface during such variable temperature sliding sequence. Results show that the protective oxide layer (glaze layer) formed at high temperature is destroyed at low temperature within a latency time. However, the high-temperature glaze layer induces a reduction of the wear volume at lower temperature compared to a standard fretting test performed at a fixed temperature condition (without initial glaze layer formation). When the glaze layer is turned into debris, it enriches the debris bed with a high proportion of cobalt element. This high concentration of cobalt element in the third body layer can clarify the lower steady state wear regime compared to an equivalent fixed temperature test condition.

Fluidisation of yield stress fluids under vibration

Motivated by the industrial processing of chocolate, we study experimentally the fluidisation of a sessile drop of yield-stress fluid on a pre-existing layer of the same fluid under vertical sinusoidal oscillations. We compare the behaviours of molten chocolate and Carbopol which are both shear-thinning with a similar yield stress but exhibit very different elastic properties. We find that these materials spread when the forcing acceleration exceeds the same threshold which is determined by the initial deposition process. However, the height reduction due to spreading is typically at least three times greater in chocolate than in Carbopol under similar forcing. Moreover, the two materials exhibit very different spreading behaviours: whereas chocolate exhibits slow long-term spreading, the Carbopol drop rapidly relaxes its stress by spreading to a new equilibrium shape with an enlarged footprint. This spreading is insensitive to the history of the forcing. In addition, the Carbopol drop performs large-amplitude oscillations with the forcing frequency, both above and below the threshold. We investigate these viscoelastic oscillations and provide evidence of complex nonlinear viscoelastic behaviour in the vicinity of the spreading threshold. In fact, for forcing accelerations greater than the spreading threshold, our drop automatically adjusts its shape to remain at the yield stress. We discuss how our vibrated-drop experiment offers a new and powerful approach to probing the yield transition in elastoviscoplastic fluids.

Fog and Low-Level Stratus in Coupled Ocean–Atmosphere Simulations of the Northern California Current System Upwelling Season

AbstractFog and low-level stratus during April–September 2009 are examined in a set of coupled ocean–atmosphere numerical simulations of the northern California Current System (CCS). The model configurations differ only in the choice of planetary boundary layer (PBL) parameterization scheme and, in one case, surface flux scheme. The results suggest that fog formation in this region primarily occurs through condensation at the surface induced locally by surface cooling, when moist offshore air is advected over cold upwelled waters and the shallow coastal marine PBL is further stabilized by warm, dry, continental air that extends offshore above the PBL inversion. These results are consistent with some but not all prior hypotheses for fog formation in the CCS region. Fog formation by downward growth of a preexisting stratus layer is also found in the simulations, but dominates only in those simulations with PBL schemes that produce an extensive and evidently unphysical stratus layer at 200 m height, which serves as the source for the downward growth. The stronger fog response in later summer months arises from seasonal warming of offshore SST, which increases the moisture content and temperature of the upstream air mass, while cool coastal SSTs are maintained by upwelling. On synoptic time scales, a similar influence of fog response on upstream conditions is found but controlled instead by changes in wind direction. These results suggest that the critical factors determining the evolution of the coastal fog regime in a warming climate are likely the temperature of upwelling source waters and the offshore flow of continental air.