Focal Stress Research Articles

Fibroblasts’ secretome from calcified and non-calcified dermis in Pseudoxanthoma elasticum differently contributes to elastin calcification

Pseudoxanthoma elasticum (PXE) is a rare disease characterized by ectopic calcification, however, despite the widely spread effect of pro/anti-calcifying systemic factors associated with this genetic metabolic condition, it is not known why elastic fibers in the same patient are mainly fragmented or highly mineralized in clinically unaffected (CUS) and affected (CAS) skin, respectively. Cellular morphology and secretome are investigated in vitro in CUS and CAS fibroblasts. Here we show that, compared to CUS, CAS fibroblasts exhibit: a) differently distributed and organized focal adhesions and stress fibers; b) modified cell-matrix interactions (i.e., collagen gel retraction); c) imbalance between matrix metalloproteinases and tissue inhibitor of metalloproteinases; d) differentially expressed pro- and anti-calcifying proteoglycans and elastic-fibers associated glycoproteins. These data emphasize that in the development of pathologic mineral deposition fibroblasts play an active role altering the stability of elastic fibers and of the extracellular matrix milieu creating a local microenvironment guiding the level of matrix remodeling at an extent that may lead to degradation (in CUS) or to degradation and calcification (in CAS) of the elastic component. In conclusion, this study contributes to a better understanding of the mechanisms of the mineral deposition that can be also associated with several inherited or age-related diseases (e.g., diabetes, atherosclerosis, chronic kidney diseases).

Choroidal arterial abnormality in central serous chorioretinopathy.

To evaluate the choroidal arterial abnormality in central serous chorioretinopathy (CSC). Fifty-two eyes from 52 patients with CSC were retrospectively evaluated. Arterial and venous ultrawide-field indocyanine green angiography were merged after color and transparency adjustments to compare the choroidal arterial and venous vasculature. Specifically, we evaluated whether the choroidal arteries directly fill the pachyvessel without interconnection of choriocapillaris (arterial pachyvessel; aPV). Then, the clinical characteristics of patients with and without arterial pachyvessel were compared. Pachyvessel under subretinal fluid was detected in 47 of 52 eyes (90.4%). An arterial pachyvessel was detected in eight of 52 eyes (15.4%). Of those eight eyes with arterial pachyvessel, seven (87.5%) showed sustained staining through the venous phase, suggesting they are arteriovenous shunt, while one eye (12.5%) showed diminished fluorescence in the venous phase, suggesting this pachyvessel was purely an artery. Patients with arterial pachyvessel experienced more CSC recurrences (non-aPV group: 2.09 ± 1.44 times vs. aPV group: 3.25 ± 1.28 times; p = 0.039) and pachychoroid neovasculopathy (PNV) development (non-aPV group: 2.3% vs. aPV group: 37.5%, p = 0.009). The presence of arterial pachyvessel in eyes with CSC may represent choroidal circulatory imbalance and focal shear stress to Bruch's membrane, leading to a chronic nature and PNV development.

Do expandable cage size and number of cages matter in transforaminal lumbar interbody fusion at L5-S1? A comparative biomechanical analysis using finite element modeling.

Expandable transforaminal lumbar interbody fusion (TLIF) cages were designed to address the limitations of static cages. Bilateral cage insertion can potentially enhance stability, fusion rates, and segmental lordosis. However, the benefits of unilateral versus bilateral expandable cages with varying sizes in TLIF remain unclear. This study used a validated finite element spine model to compare the biomechanical properties of L5-S1 TLIF by using differently sized expandable cages inserted unilaterally or bilaterally. A finite element model of X-PAC expandable lumbar cages was created and used at the L5-S1 level. This model had cage dimensions of 9 mm in height, 15° in lordosis, and varying widths and lengths. Various placements (unilateral vs bilateral) and sizes were examined under pure moment loading to evaluate range of motion, adjacent-segment motion, and endplate stress. Stability at the L5-S1 level decreased when smaller cages were used in both the unilateral and bilateral cage models. In the unilateral model, cage 1 (the smallest cage) resulted in 47.9% more motion at the L5-S1 level compared to cage 5 (the largest cage) in flexion, as well as 64.8% more motion in extension. Similarly, in the bilateral TLIF model, bilateral cage 1 led to 49.4% more motion at the L5-S1 level in flexion and 73.4% more motion in extension compared to bilateral cage 5. Unilateral insertion of cage 5 provided superior stability in flexion and surpassed cages 1-3 in extension when compared to cages inserted either unilaterally or bilaterally. Reduced motion at L5-S1 correlated with increased adjacent-segment motion at L4-5. Bilateral TLIF resulted in greater adjacent-segment motion compared to unilateral TLIF with the same-size cages. Inferior endplates experienced higher stress during flexion and extension than superior endplates, with this difference being more pronounced in the bilateral model. In bilateral cage placement, stress differences ranged from 46.3% to 60.0%, while they ranged from 1.1% to 9.6% in unilateral cages. Qualitative analysis revealed increased focal stress in unilateral cages versus bilateral cages. The authors' study shows that using a large unilateral TLIF cage may offer better stability than the bilateral insertion of smaller cages. While large bilateral cages increase adjacent-segment motion, they also provide a uniform stress distribution on the endplates. These findings deepen our understanding of the biomechanics of the available expandable TLIF cages.

The importance of nodal plane orientation diversity for earthquake focal mechanism stress inversions

Abstract Inversions of earthquake focal mechanisms are among the most accessible and reliable methods for determining crustal stress. However, the use of this method varies widely, and the assumptions that underpin it are often violated, potentially compromising stress estimates. We investigate the consequences of violating the little-studied assumption that the focal mechanisms have diverse orientations. Our approach is to employ data-informed synthetic mechanisms, with nodal plane orientations defined by recent earthquake lineaments in the Midland Basin, western Texas, and rakes consistent with slip in the mapped stress field. Using both the traditional stress inversion method that assumes constant shear stress magnitudes on the causative faults as well as a recently published variable shear stress method, we show that low fault plane diversity can cause maximum horizontal stress ( S Hmax ) orientation and relative principal stress magnitude (faulting regime) estimates to differ markedly from the true values. This problem is compounded for catalogues with even modest amounts of noise (≤15°) or few (e.g. 20) mechanisms. Significantly, traditional approaches for quantifying uncertainty such as the bootstrap can severely underestimate the true uncertainty under these circumstances. To remedy this, we provide simple tools to quantify nodal plane orientation diversity and stress inversion reliability.

Influence of intracoronary hemodynamic forces on atherosclerotic plaque phenotypes

Background and aimsCoronary hemodynamics impact coronary plaque progression and destabilization. The aim of the present study was to establish the association between focal vs. diffuse intracoronary pressure gradients and wall shear stress (WSS) patterns with atherosclerotic plaque composition. MethodsProspective, international, single-arm study of patients with chronic coronary syndromes and hemodynamic significant lesions (fractional flow reserve [FFR] ≤ 0.80). Motorized FFR pullback pressure gradient (PPG), optical coherence tomography (OCT), and time-average WSS (TAWSS) and topological shear variation index (TSVI) derived from three-dimensional angiography were obtained. ResultsOne hundred five vessels (median FFR 0.70 [Interquartile range (IQR) 0.56–0.77]) had combined PPG and WSS analyses. TSVI was correlated with PPG (r = 0.47, [95% Confidence Interval (95% CI) 0.30–0.65], p < 0.001). Vessels with a focal CAD (PPG above the median value of 0.67) had significantly higher TAWSS (14.8 [IQR 8.6–24.3] vs. 7.03 [4.8–11.7] Pa, p < 0.001) and TSVI (163.9 [117.6–249.2] vs. 76.8 [23.1–140.9] m−1, p < 0.001). In the 51 vessels with baseline OCT, TSVI was associated with plaque rupture (OR 1.01 [1.00–1.02], p = 0.024), PPG with the extension of lipids (OR 7.78 [6.19–9.77], p = 0.003), with the presence of thin-cap fibroatheroma (OR 2.85 [1.11–7.83], p = 0.024) and plaque rupture (OR 4.94 [1.82 to 13.47], p = 0.002). ConclusionsFocal and diffuse coronary artery disease, defined using coronary physiology, are associated with differential WSS profiles. Pullback pressure gradients and WSS profiles are associated with atherosclerotic plaque phenotypes. Focal disease (as identified by high PPG) and high TSVI are associated with high-risk plaque features. Clinical trial registrationhttps://clinicaltrials,gov/ct2/show/NCT03782688

Enhanced Microseismicity During Production Pumping Cessation at the San Emidio Geothermal Field (Nevada, USA) in December 2016

AbstractTectonic activity, geothermal fluids, and microseismic events (MSEs) tend to occur in similar locations as a result of spatiotemporal changes in the subsurface stress state. To quantify this association, we analyze data from a dense seismic array deployed at the San Emidio geothermal field, Nevada for 1 week in December 2016 to coincide with a 19.45‐hr shutdown of all injection and production pumping operations. 123 MSEs were detected, of which 101 occurred during the shutdown. The spatial association of the MSEs with the production wells suggests a causal relationship between the production cessation and the MSEs. Here we performed a detailed analysis to investigate reservoir material properties, distribution of seismically activated faults, and local stress state. We determined the hypocenters, magnitudes, and focal mechanisms for the MSEs, P‐wave tomographic velocity model, and local stress tensor. The results show that most MSEs occurred near the production wells. Magnitudes fall between −2.2 and 0.0 with larger events located closer to the production wells. Most MSEs occurred within a westward‐dipping normal fault zone in the reservoir associated with anomalously low P‐wave velocity values. The focal mechanism and stress inversion results show predominantly normal faulting with the maximum horizontal stress oriented north‐south. We suggest that the MSEs during shutdown were triggered on pre‐existing, small‐scale, critically stressed fault patches in the reservoir as the pore pressure increased around the production wells when the production pumping ceased. We interpret the larger MSE magnitudes closer to the production wells as a result of higher pore pressure increase.

More doubts on verb‐stranding VP ellipsis: Reply to Simpson 2023

AbstractAdvocating a verb‐stranding‐VP‐ellipsis analysis for object‐gap sentences, Andrew Simpson (“In defense of verb‐stranding VP ellipsis”) argues that under negation the “adjunct reading” is missing because it depends on focal stress, which cannot be realized on unpronounced material. No such condition holds, I maintain, and the absence of the adjunct reading reflects a syntactic absence: argument‐ellipsis sites contain no VP adjuncts. The adjunct reading emerges in some languages when the antecedent sentence is negative too, an inexplicable contingency for the verb‐stranding‐VP‐ellipsis analysis; in fact, these constructions involve polarity ellipsis (of TP), in which VP adjuncts are included. However, this derivation is not available to all languages, explaining some crosslinguistic differences in adjunct readings under negation. Finally, an optional adjunct reading may emerge in affirmative object‐gap sentences due to pragmatic enrichment, a process sensitive to context in ways that go beyond the predictions of the syntactic analysis advocated by Simpson.

Nox1-based NADPH oxidase regulates the Par protein complex activity to control cell polarization.

Cell migration is essential for many biological and pathological processes. Establishing cell polarity with a trailing edge and forming a single lamellipodium at the leading edge of the cell is crucial for efficient directional cell migration and is a hallmark of mesenchymal cell motility. Lamellipodia formation is regulated by spatial-temporal activation of the small GTPases Rac and Cdc42at the front edge, and RhoA at the rear end. At a molecular level, partitioning-defective (Par) protein complex comprising Par3, Par6, and atypical Protein Kinase (aPKC isoforms ζ and λ/ι) regulates front-rear axis polarization. At the front edge, integrin clustering activates Cdc42, prompting the formation of Par3/Par6/aPKC complexes to modulate MTOC positioning and microtubule stabilization. Consequently, the Par3/Par6/aPKC complex recruits Rac1-GEF Tiam to activate Rac1, leading to lamellipodium formation. At the rear end, RhoA-ROCK phosphorylates Par3 disrupting its interaction with Tiam and inactivating Rac1. RhoA activity at the rear end allows the formation of focal adhesions and stress fibers necessary to generate the traction forces that allow cell movement. Nox1-based NADPH oxidase is necessary for PDGF-induced migration in vitro and in vivo for many cell types, including fibroblasts and smooth muscle cells. Here, we report that Nox1-deficient cells failed to acquire a normal front-to-rear polarity, polarize MTOC, and form a single lamellipodium. Instead, these cells form multiple protrusions that accumulate Par3 and active Tiam. The exogenous addition of H2O2 rescues this phenotype and is associated with the hyperactivation of Par3, Tiam, and Rac1. Mechanistically, Nox1 deficiency induces the inactivation of PP2A phosphatase, leading to increased activation of aPKC. These results were validated in Nox1y/- primary mouse aortic smooth muscle cells (MASMCs), which also showed PP2A inactivation after PDGF-BB stimulation consistent with exacerbated activation of aPKC. Moreover, we evaluated the physiological relevance of this signaling pathway using a femoral artery wire injury model to generate neointimal hyperplasia. Nox1y/- mice showed increased staining for the inactive form of PP2A and increased signal for active aPKC, suggesting that PP2A and aPKC activities might contribute to reducing neointima formation observed in the arteries of Nox1y/- mice.

Strike‐slip deformation and expansion process of the Qilian fold‐and‐thrust belt: Inferred from gravitational potential energy

In this study, we present a new estimation of the gravitational potential energy (GPE) and explore its relationship with the present‐day stress and strain‐rate field in the Qilian fold‐and‐thrust belt (QFTB), to evaluate how the stress associated with GPE gives rise to tectonic deformation of the QFTB, and to achieve a more comprehensive understanding of stress transfer from the Indian–Eurasian collision belt to the QFTB. Significant features of the stress and deformation in the QFTB derived from our analysis include the following: (1) the stress pattern is verified by the results of the deviatoric stress being inverted by topographic stress modelling, suggesting that topographic stress associated with the lateral variations in crustal thickness and topography should be taken into account when considering the clockwise rotation of the stress field along the strike of the Qilian fold‐and‐thrust belt. (2) Our stress–strain results suggest that the strain derived from the Indian–Eurasian convergence propagated to the north of the Haiyuan Fault. By incorporating with recent seismological results, it is supposed that the Tibetan Plateau has extended to the southern Alxa block, and the Haiyuan Fault may not be the most northeastern crustal boundary of the Tibetan Plateau. (3) The comparison of surface strain, focal stress and topographic stress modelling illustrates that the Qilian fold‐and‐thrust belt is probably deforming in response to the far‐field effect of Indian–Eurasian convergence. The stress transfer from the collisional front to the Qilian fold‐and‐thrust belt appears to be continuous and progressive. Accordingly, we suggest that a diffuse model could better describe the deformation of the Qilian fold‐and‐thrust belt in which lateral expansion is accommodated evenly along the principal axes of stress as a consequence of horizontal lithospheric heterogeneity.

Which stress is on response particles? An empirical study

Polar response particles (PRPs) have been the subject of a variety of studies in semantics and pragmatics, especially in languages like English and Farsi, where the same particles, āre ‘Yes’ and na ‘No’, can be used with two readings, namely the polarity and the (dis)agreement readings. While PRPs in response to the negative questions result in ambiguity, many scholars mention the important role of the prosodic saliency in the positive answers to the negative questions. This paper is an empirical effort to capture the focal stress on PRPs in Farsi. Two experiments were conducted with respect to the polarity and the bias of the question. The first experiment confirms the earlier studies for the presence of focal stress on the opposi- tion answers to the negative questions, as well as the lack of such stress in response to the positive questions. The second experiment reveals the presence of focal stress in response to both positive and negative questions, when the questions necessarily express bias. I will propose that two types of focal stress, namely Contrastive Focus and Verum Accent, perform two different functions. In the first experiment, the con- trastive focus helps to disambiguate PRPs when required, while the Verum accent in the second study is to indicate the conflict between the addressee’s response and the speaker’s (bias) expectation.

On the role of myosin-induced actin depolymerization during cell migration.

Mammalian cell migration in open spaces requires F-actin polymerization and myosin contraction. While many studies have focused on myosin's coupling to focal adhesion and stress fibers, the indirect effect of myosin contraction on cell migration through actin depolymerization is not well studied. In this work, we quantified how cell velocity and effective power output are influenced by the rate of actin depolymerization, which is affected by myosin contraction. In addition, we derived scaling laws to provide physical insights into cell migration. Model analysis shows that the cell migration velocity displays a biphasic dependence on the rate of actin depolymerization and myosin contraction. Our model further predicts that the effective cell energy output depends not only on the cell velocity but also on myosin contractility. The work has implications on in vivo processes such as immune response and cancer metastasis, where cells overcome barriers imposed by the physical environment.

Focal Mechanisms and Stress Field Characteristics of Microearthquakes in Baihetan Reservoir in the Downstream Area of Jinsha River

The Baihetan Reservoir was impounded on 6 April 2021, after which the water level rose significantly. Notably, after one week of impoundment, microseismic activities were prominent around the reservoir area, which was highly associated with the water level change. From 6 April 2021 to 31 December 2021, over 7000 microearthquakes were recorded by the seismic stations in the vicinity of the reservoir, including 12 ML &gt; 3 events. The maximum was the 21 December 2021 ML3.9 earthquake in Qiluogou town, Sichuan. The post-impoundment seismic events were clustered in Hulukou town in the Qiaojia Basin, with an overall “Y-shaped” pattern. In this study, taking advantage of the high-frequency waveform matching approach, the pre- and post-impoundment focal mechanism solutions totaling 207 ML &gt; 2 earthquakes are successfully obtained. The impoundment-induced stress change is analyzed, and the iterative joint inversion method is used to invert the stress field. Major results and conclusions include the following: (1) After impoundment, the number of normal fault earthquakes remarkably increased in the reservoir area; (2) Impoundment has led to a vertical compressive stress field and horizontal tensile stress field in the area where microearthquakes occurred. It is necessary to pay close attention to possible moderate-to-strong earthquakes in the future.

Using Corrected and Imputed Polarity Measurements to Improve Focal Mechanisms in a Regional Earthquake Catalog Near the Mt. Lewis Fault Zone, California

AbstractWe utilized relative polarity measurements and machine learning techniques to better resolve focal mechanisms and stress orientations considering a catalog of ∼29,000 relocated earthquakes that occurred during 1984–2021 in the southeastern San Francisco Bay Area. Earthquake focal mechanisms are commonly produced using P wave first motion polarities, which traditionally requires events to be well‐recorded across a seismic network with good focal sphere coverage. We adapted recently developed approaches that are less dependent on high signal‐to‐noise records and exploit similar waveforms to produce relative polarity and amplitude measurements between earthquake pairs. These techniques were previously only applied on localized earthquake sequences, and we further developed these approaches so that they can be utilized for regional catalogs. We validated or corrected manually identified polarities by performing polarity consensuses using earthquake pairs. Missing and unreliable polarity measurements were imputed using iterative random forests, an unsupervised ensemble machine learning method. Relative P and S wave amplitude measurements were made between earthquakes, constraining S/P ratios for low signal‐to‐noise waveforms. Using these techniques, we were able to reduce focal mechanism uncertainties by an average of ∼13° and produced well‐constrained focal mechanisms for ∼6 times as many earthquakes than those produced using only the traditionally derived polarities. We performed stress inversions using the focal mechanisms by grouping the focal mechanism results into a quadtree structure. Our stress results are consistent with previous work, albeit at a higher spatial resolution, and demonstrate these techniques can aid our understanding of fault structures and kinematics in more detail than was previously possible.

Processing Focus in Turkish

The immediately preverbal position has been argued to be the default focus position in Turkish. In absence of any overt focus markers, the constituent in this position is considered to carry sentential stress and neutral information for canonical word-order sentences and focus is projected to the whole sentence in the form of broad focus. In non-canonical word-order sentences, the immediately preverbal constituent is presumed to carry focal stress and the focused constituent would receive narrow focus. This paper tested this claim experimentally. The paper also investigated if there were any differences in the cognitive operations associated with processing and revising focus in canonical and non-canonical sentences. There were a sentence completion task and an eye-tracking experiment. The sentence completion data and the eye-tracking data supported the theoretical predictions: the immediately preverbal position was associated with default focus in Turkish when no pitch accentuation or other focus markers were available. The eye-tracking data further showed that changes to word-order were perceived as cues for broad versus narrow focus marking. The participants’ processing of and revision from narrow focus were costlier than processing broad focus and assigning narrow focus for the first time. We argue, in line with previous research, that this may be due to deeper encoding of focused information in memory or heavier memory load resulting from keeping a set of alternatives of the focused constituent when it has contrastive meaning.

Graded stiffness offloading insoles better redistribute heel plantar pressure to protect the diabetic neuropathic foot

BackgroundDiabetic heel ulceration is a common, detrimental, and costly complication of diabetes. This study investigates a novel “graded-stiffness” offloading method, which consists of a heel support with increasing levels of stiffness materials to better redistribute plantar pressure for heel ulcer prevention and treatment. Research questionIs the novel “graded-stiffness” solution better able to redistribute heel pressure and reduce focal stress concentration areas of the heel? MethodsTwenty healthy young men walked with four, 3D-printed, insole configurations. The configurations included the “graded-stiffness” insoles with and without an offloading hole under the heel tissue at risk for ulcerations and two conventional offloading supports of flat insoles with no offloading and simple holed offloading insoles. In-shoe plantar pressure was measured using the Pedar-X system. Peak pressure and pressure dose were measured at three heel regions: offloaded region, perimeter of offloaded region, and periphery region. ResultsThe simple offloading configuration reduced pressure at the offloaded region; however, pressure at the perimeter of the offloading region significantly increased. With respect to ANOVA, the “graded-stiffness” offloading configurations were more effective than existing tested solutions in reducing and redistributing heel peak pressure and pressure dose, considering all heel regions. SignificanceThe “graded-stiffness” offloading solution demonstrated a novel flexible and customized solution that can be manufactured on-demand through a precise selection of the graded-stiffness offloading location and material properties to fit the shape and size of the ulcer. This study is a follow-up in-vivo pilot study, in a healthy population group, to our previous computation modeling work that reported the efficiency of the “graded-stiffness” configuration, and which emphasizes its potential for streamlining and optimizing the prevention and treatment of diabetic heel ulcers.

Vitronectin acts as a key regulator of adhesion and migration in human umbilical cord-derived MSCs under different stress conditions

To improve mesenchymal stem cell (MSC)-based therapy efficacy, it is critical to identify factors involved in regulating migration and adhesion of MSCs under microenvironmental stress conditions. We observed that human Wharton's jelly-derived MSCs (WJ-MSCs) exhibited increase in cell spread area and adhesion, with reduction in cellular migration under serum starvation stress. The changes in adhesion and migration characteristics were accompanied by formation of large number of super mature focal adhesions along with extensive stress fibres and altered ECM gene expression with notable induction in vitronectin (VTN) expression. NF-κβ was found to be a positive regulator of VTN expression while ERK pathway regulated it negatively. Inhibition of these signalling pathways or knocking down of VTN under serum starvation established the correlation between increase in VTN expression and increased cellular adhesion with corresponding reduction in cell migration. VTN knockdown also resulted in reduction of super mature focal adhesions and extensive stress fibres, formed under serum starvation stress. Additionally, VTN induction was not detected in hypoxia-treated WJ-MSCs, and the MSCs showed no significant change in the adhesion or migration properties under hypoxia. VTN is established as a key player which possibly regulates the adhesion and migration properties of WJ-MSCs via focal adhesion signalling.

Seismotectonic model of High-Middle Atlas Junction (Morocco) derived from earthquake focal mechanism and stress tensor analysis

Seismotectonic model of High-Middle Atlas Junction (Morocco) derived from earthquake focal mechanism and stress tensor analysis

1D micro-nanopatterned integrin ligand surfaces for directed cell movement.

Cell-extracellular matrix (ECM) adhesion mediated by integrins is a highly regulated process involved in many vital cellular functions such as motility, proliferation and survival. However, the influence of lateral integrin clustering in the coordination of cell front and rear dynamics during cell migration remains unresolved. For this purpose, we describe a novel protocol to fabricate 1D micro-nanopatterned stripes by integrating the block copolymer micelle nanolithography (BCMNL) technique and maskless near UV lithography-based photopatterning. The photopatterned 10μm-wide stripes consist of a quasi-perfect hexagonal arrangement of gold nanoparticles, decorated with the RGD (arginine-glycine-aspartate) motif for single integrin heterodimer binding, and placed at a distance of 50, 80, and 100nm to regulate integrin clustering and focal adhesion dynamics. By employing time-lapse microscopy and immunostaining, we show that the displacement and speed of fibroblasts changes according to the nanoscale spacing of adhesion sites. We found that as the lateral spacing of adhesive peptides increased, fibroblast morphology was more elongated. This was accompanied by a decreased formation of mature focal adhesions and stress fibers, which increased cell displacement and speed. These results provide new insights into the migratory behavior of fibroblasts in 1D environments and our protocol offers a new platform to design and manufacture confined environments in 1D for integrin-mediated cell adhesion.

Seismicity and Stress State in the Ryukyu Islands Subduction Zone

Based on the newly compiled and mostly complete unified earthquake catalogue for China’s seas and adjacent areas, further information was obtained about the structural shape and dip angle of the Benioff zone in the Ryukyu Islands subduction zone during the different subduction stages. In addition, using the damped regional stress tensor inversion method, we were able to investigate the complex stress field characteristics and the dynamic significance of the shallow and intermediate earthquakes in the Ryukyu Islands subduction zone. The results show that the tectonic stress field of the Ryukyu Islands subduction zone was extensional along the subduction direction in the northern area of the Tokara Strait and was compressional along the subduction direction in the southern area of the Tokara Strait. The R value of the shallow stress field of the Okinawa Trough was low, and the σ3 was stable in the NNW direction with a small dip angle (&gt;30°). The type of stress field in the shallow part of the Okinawa Trough transitioned from strike-slip type to normal fault type from north to south, reflecting the difference in the degree of development of the trough, and the southern segment of the trough began to transform into the expansion stage. The northeastern portion of the study area and southeast Taiwan constituted the high R value (0.68–0.87) region where the σ2 had tensile components. The stress state was biaxial tension–uniaxial compression, and the principal compressive stress was determined to be in the SEE direction with a large dip angle (&gt;30°). The σ1 in northeast Taiwan exhibited a nearly vertical (&gt;60°) plunge, while the σ2 and σ3 were nearly horizontal. The σ2 was thrust in the ENE–WSW direction, and the σ3 was extended in the NNW direction. Through this research, a greater understanding has been gained of the seismicity characteristics and shape of the Ryukyu Islands subduction zone. Supplementary research has also been completed on the focal mechanism solution and stress field of the Ryukyu Islands subduction zone. Finally, this research is important for earthquake hazard analysis and earthquake engineering safety evaluation in this area.

Utilizing Micro-CT Imaging To Define Collagen Remodeling In Non-native Tissue Geometries

Existing research on anastomotic leak focuses on biologic etiologies, but few have studied how the creation of non-native geometry affects local tissue biomechanics. Preliminary work demonstrates that a newly created anastomosis has geometrically defined focal stress points. We postulate that collagen remodeling is particularly strained at these points, which become future sites of leak in the setting of local bacterial interactions. Utilizing a mouse model, we aim to demonstrate failure in collagen remodeling in both bowel and aorta.