Deep Portion Research Articles

Impact of Down‐Dip Rupture Limit and High‐Stress Drop Subevents on Coseismic Land‐Level Change during Cascadia Megathrust Earthquakes

AbstractSeismic hazard associated with Cascadia megathrust earthquakes is strongly dependent on the landward rupture extent and heterogeneous fault properties. We use 3D numerical simulations and a seismic velocity model for Cascadia to estimate coseismic deformation due to M 9–9.2 earthquake scenarios. Our earthquake source model is based on observations of the 2010 M 8.8 Maule and 2011 M 9.0 Tohoku earthquakes, which exhibited distinct strong motion‐generating subevents in the deep portion of the fault. We compare our estimates for land‐level change to paleoseismic estimates for coseismic coastal subsidence during the A.D. 1700 Cascadia earthquake. Results show that megathrust rupture extending to the 1 cm/yr locking contour provides a good match to geologic data. In addition, along‐strike variations in coastal subsidence can be matched by including low slip, strong motion‐generating subevents in the down‐dip region of the megathrust. This work demonstrates the potential to improve seismic hazard estimates for Cascadia earthquakes by comparing physics‐based earthquake simulations with geologic observations.

Serratus Anterior Contraction During Resisted Arm Extension (GravityFit) Assessed by MRI.

BackgroundScapular stabilization is a common focus of shoulder rehabilitation.ObjectiveExamine contraction of serratus anterior during a bilateral arm extension exercise with axial compression using an exercise device (GravityFit) by magnetic resonance imaging (MRI).MethodsMRI was performed under two conditions: rest and static arm extension with axial compression. Load was set at 20% of age, sex and weight estimated bench press one-repetition maximum. A T2-weighted sequence was used to collect 14 axial images of the upper thoracic spine and shoulder bilaterally. Mean muscle length and thickness were calculated for the whole muscle and in equidistant subregions of the muscle in its anterior (superficial), central and posterior (deep) portions. Adjustment of p-values to guard against false positives was performed via the false discovery rate method.ResultsNine participants without a history of shoulder or spine pathology were included. When compared to rest, arm extension with the exercise device led to 11% increased overall muscle thickness (P = 0.038) and 6.1% decreased overall muscle length (P = 0.010). Regionally, thickness increased in anterior (superficial, +19%; P = 0.040) and central (+17%; P = 0.028) portions of the muscle more than posterior (deep, +3.9%, P = 0.542).ConclusionContraction of serratus anterior occurred during static arm extension with axial compression produced by a novel exercise approach, as measured via MRI. The activation of serratus anterior differed across its length with greater contraction of the anterior and central portions. This may indicate compartmentalization of function within this muscle. Overall, the proof-of-principle findings justify the use of this exercise approach for the activation of serratus anterior.

Serpentinite-derived low δ7Li fluids in continental subduction zones: Constraints from the fluid metasomatic rocks (whiteschist) from the Dora-Maira Massif, Western Alps

Whole rock lithium (Li) and Li isotopic compositions of coesite-bearing whiteschists and their country rock metagranites from the Dora-Maira Massif in the Western Alps were investigated to understand their behavior during fluid-rock interaction in mantle depths of continental subduction zones. The whiteschists reveal relatively low δ7Li values (−6.4‰ to +2.4‰, with an average value of −2.1‰) in comparison to the country rock metagranites (δ7Li = −1.2‰ to +3.6‰, with an average value of +1.4‰). The δ7Li values of whiteschists do not show any correlations with major elements (e.g. Mg, Fe), Li, or isotopes (i.e., δ26Mg and δ18O values) and cannot be explained by kinetic fractionation. Hence, the low δ7Li values of whiteschists result from interactions with metasomatic fluids containing isotopically light Li that occurred in deep portions of a continental subduction zone. Fluid-rock interaction modeling suggests that the metasomatic fluids contain low δ7Li values (down to −4‰) and moderate Li concentrations (50 to 150 ppm), which were probably derived from the dehydration of serpentinites in the subduction channel. The presence of such low δ7Li fluids in deep subduction zones could cause Li isotopic heterogeneity in the earth's interior.

Visualization and Quantification of Digitally Dissected Muscle Fascicles in the Masticatory Muscles of Callithrix jacchus Using Nondestructive DiceCT.

The organization and length of a muscle's fascicles imparts its contractile properties. Longer fascicles permit increased muscle excursion, whereas changes in fascicle orientation relate to the overall vector of contractile force. Collecting data on fascicle architecture has traditionally involved destructive and irreversible gross dissection. In recent years, however, new imaging modalities have permitted muscles and their fascicles to be visualized nondestructively. Here, we present data from a primate (Callithrix jacchus), in which, for the first time, individual muscle fascicles are digitally "dissected" (segmented and reconstructed) using nondestructive, high-resolution diffusible iodine-based contrast-enhanced computed tomography (DiceCT) techniques. We also present quantitative data on the length and orientation of these fascicles within 10 muscle divisions of the jaw adductor and abductor musculature (superficial, deep, and zygomatic portions of temporalis and masseter; medial and lateral pterygoid; anterior and posterior digastric) and compare these digitally measured lengths to fascicular lengths measured using traditional gross and chemical dissection. Digitally derived fascicle lengths correspond well to their dissection-derived counterparts. Moreover, our analyses of changes in fascicle orientation across the adductor complex enable us to visualize previously uncharacterized levels of detail and highlight significant variation between adjacent muscle layers within muscle groups (e.g., between superficial, deep, and zygomatic portions of masseter and temporalis). We conclude that this technique offers great potential to future research, particularly for questions centered around the visualization and quantification of obscured and often-overlooked muscles such as the pterygoid and digastric muscles, and for deriving more accurate models of the masticatory system as a whole. Anat Rec, 302:1891-1900, 2019. © 2019 American Association for Anatomy.

Upper mantle shear velocity structure beneath the equatorial East Pacific Rise from array-based teleseismic surface-wave dispersion analysis

Summary The Discovery/Gofar transform faults system is associated with a fast-spreading center on the equatorial East Pacific Rise. Most previous studies focus on its regular seismic cycle and crustal fault zone structure, but the characteristics of the upper mantle structure beneath this mid-ocean ridge system are not well known. Here we invert upper mantle shear velocity structure in this region using both teleseismic surface waves and ambient seismic noise from 24 ocean bottom seismometers (OBSs) deployed in this region in 2008. We develop an array analysis method with multi-dimensional stacking and tracing to determine the average fundamental mode Rayleigh wave phase-velocity dispersion curve (period band 20–100 s) for 94 teleseismic events distributed along the E-W array direction. Then, we combine with the previously measured Rayleigh wave phase-velocity dispersion (period band 2–25 s) from ambient seismic noise to obtain the average fundamental mode (period band 2–100 s) and the first-higher mode (period band 3–7 s) Rayleigh wave phase-velocity dispersion. The average dispersion data are inverted for the 1-D average shear wave velocity (Vs) structure from crust to 200-km depth in the upper mantle beneath our study region. The average Vs between the Moho and 200-km depth of the final model is about 4.18 km/s. There exists an ∼5-km thickness high-velocity lid (LID) beneath the Moho with the maximum Vs of 4.37 km/s. Below the LID, the Vs of a pronounced low-velocity zone (LVZ) in the uppermost mantle (15–60 km depth) is 4.03–4.23 km/s (∼10 per cent lower than the global average). This pronounced LVZ is thinner and shallower than the LVZs beneath other oceanic areas with older lithospheric ages. We infer that partial melting (0.5–5 per cent) mainly occurs in the shallow upper mantle zone beneath this young (0–2 Myr) oceanic region. In the deeper portion (60–200 km depth), the Vs of a weak LVZ is 4.15–4.27 km/s (∼5 per cent lower than the global average). Furthermore, the inferred lithosphere-asthenosphere boundary (LAB) with ∼15-km thickness can fit well with the conductive cooling model. These results are useful for understanding the depth distribution and melting characteristics of the upper mantle lithosphere and asthenosphere in this active ridge-transform fault region.

Seismic imaging of the Olduvai Basin, Tanzania

A 5.6-km-long line of refraction and reflection seismic data spanning the Pliocene-Pleistocene fill of the Olduvai Basin, Tanzania is presented. The line is oriented along a northwest-southeast profile through the position of Olduvai Gorge Coring Project (OGCP) Borehole 2A. Our aims are to (1) delineate the geometry of the basin floor by tracing bedrock topography of the metaquartzitic and gneissic basement, (2) map synsedimentary normal faults and trace individual strata at depth, and (3) provide context for the sequence observed in OGCP cores. Results with refraction tomography and poststack migration show that the maximum basin depth is around 405 m (±25 m) in the deepest portion, which quadruples the thickness of the basin-fill previously known from outcrops. Variations in seismic velocities show the positions of lower density lake claystones and higher density well-cemented sedimentary sequences. The Bed I Basalt lava is a prominent marker in the refraction seismic results. Bottom-most sediments are dated to >2.2 Ma near where Borehole 2A bottoms out at the depth of 245 m. However, the seismic line shows that the basin-fill reaches a maximum stratigraphic thickness of around 380 m deep at Borehole 2A, in the western basin where the subsidence was greatest. This further suggests that potential hominin palaeoenvironments were available and preserved within the basin-fill possibly as far back as around 4 Ma, applying a temporal extrapolation using the average sediment accretion rate.

Safety and Efficacy of Minimally Invasive Stereotactic Aspiration with Multicatheter Insertion Compared with Conventional Craniotomy for Large Spontaneous Intracerebral Hemorrhage (≥50 mL)

Conventional craniotomy (CC) is generally favored for treating large intracerebral hemorrhage (ICH), but the feasibility of minimally invasive stereotactic aspiration for large ICH is controversial. We investigated the efficacy and safety of stereotactic aspiration with multicatheter insertion (SAMCI) for large ICH (≥50 mL). In January 2014, we implemented SAMCI for large ICH. The inclusion criteria for SAMCI were as follows: 1) spontaneous supratentorial ICH, 2) ICH volume ≥50 mL, 3) Glasgow Coma Scale score ≥5, and 4) no bilateral fixed dilated pupils. Forty-seven patients who underwent SAMCI from January 2014 to July 2018 composed the SAMCI group, and 34 patients who underwent CC between January 2010 and December 2013 and retrospectively met the inclusion criteria for SAMCI composed the control group (CC group). The mean preoperative ICH volume in the SAMCI and CC groups was 73.1 ± 22.8 and 72.4 ± 21.5 mL, respectively. There were no significant differences between the groups in baseline characteristics except for ICH location. The deep portion of the ICH was higher in the SAMCI group than in the CC group. Postoperative mortality and rebleeding rates were significantly lower in the SAMCI group than in the CC group (4.3% vs. 26.5% and 0% vs. 14.7%, respectively; P < 0.05). Logistic regression analysis showed that SAMCI contributed to a decrease in the mortality rate (odds ratio, 0.04; P= 0.008). SAMCI is a feasible therapeutic option for large ICH and has low complication rates.

Molecular alterations of human lumbar yellow ligament related to the process of intervertebral disk degeneration and stenosis.

The objective of this study was to analyze the layers of yellow ligament in lumbar canal stenosis and disk herniation. Eighteen ligaments were harvested from patients with lumbar spinal canal stenosis. Twenty-nine normal samples from lumbar spine disk herniation patients served as control. All surgical procedures were the same. Ligaments were stained in hematoxylin and eosin; picrosirius-hematoxylin for collagen; Weigert's resorcin-fuchsin for elaunin, oxytalan and elastic fibers; and transmission electron microscopy. Immunohistochemistry was performed for Il-6; Il-10; and CD-31, PGP9.5. Results are described in means and standard error (mean ± SE), and all analyses adopted the significance level of P < 0.05. Spinal stenosis ligaments were 2.5 × thicker. Control superficial ligaments presented a large number of thick, compact collagen fibers and a significant amount of oxytalan and mature elastic fibers. The deep layer presented a large number of mature elastic fibers. In the stenosis group, collagen was thinner and compacted in both layers. There was no difference in the interleukin profile among groups. The deep portion of the stenosis group presented a higher number of vessels and nerves. Two layers compose the elastic system of the normal ligamentum flavum, where the deep portion is mainly responsible for its elasticity (elaunin fibers), while its resistance depends on the concentration of oxytalan fibers, which are more present in the superficial layer. Ligamentum flavum in the stenosis samples presents more mononuclear infiltrate and more degraded elastic fibers with a higher number of vessels in its deep portion. These slides can be retrieved under Electronic Supplementary Material.

Face Dissection as the Plastic Surgery Approach: Effective Method in Residency Training.

The global trend of resident work-hour restrictions requires a more time efficient way of resident training. Among many training programs for learning the facial anatomy, the cadaver is the most similar to live patients. A cadaver should be used as efficiently as possible due to human dignity as well as the consideration of cost. The authors designed an effective cadaver dissection method in learning facial anatomy using the plastic surgery approach. A 51-year-old male cadaver was used for dissection. The program was proceeded 6 times over 6 weeks, and 4 to 8 hours each day. We used standard surgical instruments with magnifying loupes. The results were analyzed through a numerical scale survey. We planned to dissect the face from medial to lateral, cephalic to caudal, and superficial to deep portion. The overall knowledge and confidence level of the face were increased in all 7 participants. The mean knowledge level before and after the seminar was 3.00 and 4.03, respectively. Confidence level also increased through the seminar from 1.86 to 2.86. The authors believe this cadaver dissection program could optimize learning anatomical knowledge and improve resident's surgical confidence through a wide range of procedures.

The characteristics of the lobular arrangement indicate the dynamic role played by the infrapatellar fat pad in knee kinematics.

The infrapatellar fat pad (IFP) is an intracapsular but extrasynovial structure, located between the patellar tendon, the femoral condyles and the tibial plateau. It consists of white adipose tissue, organised in lobules defined by thin connective septa. The aim of this study is the morphometric and ultrasonographic analysis of IFP in subjects without knee pathology during flexion-extension movements. The morphometric study was conducted on 20 cadavers (15M, 5F, mean age 80.2years). Ultrasound was performed on 24 volunteers with no history of knee diseases (5M, 19F, mean age: 45years). The characteristics of the adipose lobules near the patellar tendon and in the deep portion of the IFP were evaluated. Numerical models were provided, according to the size of the lobules. At histological examination, the adipose lobules located near the patellar tendon were larger (mean area 12.2mm2 ±5.3) than those at a deeper level (mean area 1.34mm2 ±0.7, P<0.001) and the thickness of the septa of the deepest adipose lobules (mean value 0.35mm±0.32) was greater than that of the superficial one (mean value 0.29mm±0.25, P<0.001). At ultrasound, the IFP was seen to be composed of very large lobules in the superficial part (mean area 0.29cm2 ±0.17 in extension), with a significant reduction in flexion (mean area 0.12cm2 ±0.07, P<0.01). The deep lobules were smaller (mean area 0.11cm2 ±0.08 in extension) and did not change their values (mean area 0.19cm2 ±0.52 in flexion, P>0.05). In the sagittal plane, the reduction of thickness of the superficial layer (with large adipose lobules) during flexion was 20.6%, whereas that of the deep layer (with small adipose lobules) was 1.3%. Numerical simulation of vertical loads, corresponding to flexion of the knee, showed that stress mainly developed within the interlobular septa and opposed bulging of the lobules. The characteristics of the lobular arrangement of the IFP (large lobules with superficial septa in the superficial part and small lobules with thick septa in the deep one), significant changes in the areas and perimeters of the superficial lobules, and the reduced thickness of the superficial layer during flexion all indicate the dynamic role played by the IFP in knee kinematics.

Three‐Dimensional Masticatory Muscle Fascicular Orientation in a Digitally Dissected Callithrix jacchus

Diffusible iodine-based contrast-enhanced computed tomography (DiceCT) has been increasingly used to study the functional morphology of soft-tissues. Where traditional CT is ineffective at allowing the differentiation of lower density structures, the iodine in the DiceCT process binds to myological carbohydrates, increasing their density and thus allowing clear visualization of muscles. When done carefully (i.e., with the right concentrations of iodine, for the right amount of time and with intermediate evaluation of diffusion rates), the DiceCT procedure can yield results that allow individual fascicles within specific sections of muscles to be isolated for analysis. Following these procedures, we studied a subset of muscle fascicles from each part of the mandibular adductors (superficial, deep and zygomatic portions of the masseter and temporalis as well as the two heads of medial pterygoid) and the lateral pterygoid of a common marmoset, Callithrix jacchus. We also segmented the skull and aponeuroses to which each of the masticatory muscles attaches. Because we segmented representative fascicles from throughout each muscle portion, we are able to show, for the first time, the angularity of these fascicles relative to each other in three dimensions. We also used traditional gross dissection of these same muscle divisions from the same specimen, followed by chemical dissection and traditional fascicle analysis (including sarcomere measurement). Comparison of these data demonstrates relative congruence between the physically and digitally measured fascicle lengths, with an average variance of 10% between the two techniques. Beyond this confirmation that these digital fascicle dissections yield comparable results to those achieved using traditional methods, this new fascicle-by-fascicle digital dissection reveals other important anatomical findings: 1) the majority of the fascicles are measurably curved when the jaws are at near occlusion. The sarcomeres of each of the adductors were also shorter than their optimal tension length. Thus, near occlusion, fascicles are compressed at both the gross and cellular level, and previous studies that have made assumptions about bite force based on these near occlusion fascicle lengths need to better account for the fact that these fascicles would need to be stretched to wider gapes prior to providing active bite force. 2) The visualization also clearly shows that superficial muscle portions have substantially different fascicle orientations than deeper muscle portions. Thus, it is not possible to physically slice apart muscles based on external appearance without slicing through fascicles, and all studies that have relied on that method have, therefore, almost certainly underestimated fascicle lengths. Lastly, 3) this approach has yielded the first clear visualization of the in situ fascicle orientation of the lateral pterygoid – a muscle that is so inaccessible to traditional gross dissection that it has been largely ignored by masticatory anatomists. However, this anterior translator is of great importance in some taxa, like this gouging C. jacchus, and its visualization may yield new and valuable functional insight. Support or Funding Information This project was supported by the NSF (IOS-15-57125). Fascicle-by-fascicle dissection of Callithrix jacchus masticatory muscles. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Cretaceous extensional systems of the Golfo San Jorge basin: Insights from the analysis of fault length and displacement data

Displacement profiles and maps were used in the subsurface of the Golfo San Jorge basin in the Manantiales Behr region to analyze factors affecting the geometric and kinematic evolution of an extensional system and its relationship with the migration and trapping of hydrocarbons. Two fault types were recognized: faults affecting both the basement and the sedimentary cover, and faults restricted to the sedimentary cover. The vertical growth of the faults within the sedimentary cover was constrained by vertical lithologic variations and by intersection with the free surface. Faults involving the basement are synsedimentary and show Dmax/L relationships and aspect ratios that allow their distinction from the shallower fault planes. The geometric coherence shown in the aggregated displacement profile and map suggests a synchronous kinematic evolution for the faults developed inside the sedimentary cover. Observed fault trace lengths and throw values distributions may indicate that those faults grew by the early linkage of isolated fault segments followed by the progressive building of displacement. Reactivation of pre-existent basement fabric had little influence on faulting across overlying sedimentary cover probably because the fine-grained beds of Pozo D-129 Formation acted as a structural decoupling level. The low degree of connection between the shallow and deep portions of the faults disregards the hypothesis of vertical migration from a local source pod. The mapping of fault segments with higher values of displacement and the recognition of transfer zones may help to locate and delineate footwall hydrocarbon traps. Comparison and integration with other studies show that Cretaceous fault systems in the eastern Golfo San Jorge basin have grown mainly by rapid length establishment and subsequent displacement accumulation. Also, most of the basement-involved structures do not connect significantly with overlying fault arrays.

An integrated microbiological and electrochemical approach to determine distributions of Fe metabolism in acid mine drainage-induced "iron mound" sediments.

Fe(III)-rich deposits referred to as “iron mounds” develop when Fe(II)-rich acid mine drainage (AMD) emerges at the terrestrial surface, and aeration of the fluids induces oxidation of Fe(II), with subsequent precipitation of Fe(III) phases. As Fe(III) phases accumulate in these systems, O2 gradients may develop in the sediments and influence the distributions and extents of aerobic and anaerobic microbiological Fe metabolism, and in turn the solubility of Fe. To determine how intrusion of O2 into iron mound sediments influences microbial community composition and Fe metabolism, we incubated samples of these sediments in a column format. O2 was only supplied through the top of the columns, and microbiological, geochemical, and electrochemical changes at discrete depths were determined with time. Despite the development of dramatic gradients in dissolved Fe(II) concentrations, indicating Fe(II) oxidation in shallower portions and Fe(III) reduction in the deeper portions, microbial communities varied little with depth, suggesting the metabolic versatility of organisms in the sediments with respect to Fe metabolism. Additionally, the availability of O2 in shallow portions of the sediments influenced Fe metabolism in deeper, O2-free sediments. Total potential (EH + self-potential) measurements at discrete depths in the columns indicated that Fe transformations and electron transfer processes were occurring through the sediments and could explain the impact of O2 on Fe metabolism past where it penetrates into the sediments. This work shows that O2 availability (or lack of it) minimally influences microbial communities, but influences microbial activities beyond its penetration depth in AMD-derived Fe(III) rich sediments. Our results indicate that O2 can modulate Fe redox state and solubility in larger volumes of iron mound sediments than only those directly exposed to O2.

Histological and Histochemical Studies on the Lingual Tonsil of the Buffalo (Bubalus bubalis)

The study was conducted on lingual tonsil of six adult buffaloes (5-6 years of age) of the local mixed breed to explore histomorphological characteristics with functional significance. The mucosal surface of the lingual tonsil lined by stratified squamous keratinized epithelium was comprised of strata basale, spinosum, granulosum and corneum whereas towards the deeper folds the epithelium was stratified squamous non-keratinized. The latter epithelium modified into reticular epithelium especially toward the deeper portion and was characterized by a reduced number of epithelial cells, loss of distinct strata and heavy infiltration of lymphoid cells. The propria submucosa had loose irregular connective tissue along with glandular and lymphoid tissue. The lymphoid tissue was mainly distributed in the form of lymphoid follicles and diffused arrangement. The follicles of varying shapes and size showed darkly stained corona and lightly stained germinal centre were surrounded by parafollicular areas. The parafollicular areas possessed high endothelial venules (HEVs) with large sized endothelial cells having round to oval nuclei with distinctly visible centric or eccentric nucleoli. These HEVs are involved in trafficking of lymphocytes by transendothelial and interendothelial migration. The mucous glandular acini presented strong reactions for glycogen, acidic mucopolysaccharides, weakly sulfated mucosubstances, hyaluronic acid, sialomucins and mucins as demonstrated by different histochemical techniques. The secretions of acini also showed the presence of more than 4% content of cysteine. The presence of modified reticular epithelium and associated lymphoid tissue suggested that the lingual tonsil may be involved in sampling of oral antigens and transporting them to the underlying mucosal lymphoid tissue for processing and initiation of immune responses. The future microbiological studies may exploit the tonsil as a targeted organ for improved delivery of existing mucosal vaccines and development of new strategies for oral vaccines.

Histologic and Histomorphometric Analyses of De-epithelialized Free Gingival Graft in Humans.

A graft's histologic composition depends on the harvesting technique used, and different connective tissue-harvesting procedures have been described in the literature. Some authors suggest the submucosal tissue not be incorporated into the graft because it may interfere with the graft revascularization. In those cases, the de-epithelialized gingival graft (DGG) is obtained with a superficial harvesting technique that leaves the deep portion of the submucosa and the periosteum excluded from the graft. The aim of this case series was to histologically and histomorphometrically evaluate the tissue obtained with this technique. The findings demonstrated that the DGG was mainly composed of connective tissue, and adipose tissue was in minimal proportions. However, epithelium was found in all of the samples.

Thermal maturity structures in an accretionary wedge by a numerical simulation

This study investigates the thermal maturity structure of the accretionary wedge along with the thermal history of sediments during wedge formation using a numerical simulation. The thermal maturity, which is described in terms of vitrinite reflectance, is determined using the temperature and duration of exposure based on the particle trajectories within the accretionary wedge. This study revealed the variability in the thermal maturity even though sediments are observed to originate at an identical initial depth and thermal conditions. We propose two end-member pathways of sediment movement in the accretionary wedge during wedge growth: a shallow, low thermal maturity pathway and a deep, high thermal maturity pathway. These shallow path sediments, which move into the shallow portion of the wedge during wedge growth through accretion, rarely experience high temperatures; therefore, their thermal maturity is low. However, the sediments subducted in the deep portion of the wedge experience high temperatures and obtain high thermal maturity as a function of the deep high thermal maturity pathway. Simultaneously, a geological deformation event, such as faulting, defines the steps of thermal maturity. The small step of thermal maturity is formed by the frontal thrusting and can be preserved as a function of the shallow low thermal maturity pathway. However, the step is overprinted and is observed to disappear through the deep high thermal maturity pathway. The large step of thermal maturity is formed by long-term displacement along an out-of-sequence thrust (OOST) in the deep portion of the wedge.

Physics of Deep Surge in an Automotive Turbocharger Centrifugal Compression System

Deep surge is a violent fluid instability that occurs within turbomachinery compression systems and limits the low-flow operating range. It is characterized by large amplitude pressure and flow rate fluctuations, where the cross-sectional averaged flow direction alternates between forward and reverse. The present study includes both measurements and predictions from a turbocharger centrifugal compressor installed on a gas stand. A three-dimensional (3D) computational fluid dynamics (CFD) model of the compression system was constructed to carry out unsteady surge predictions. The results included here capture the transition from mild to deep surge, as the flow rate at the outlet boundary (valve) is reduced. During this transition, the amplitude of pressure and flow rate fluctuations greatly increase until they reach a repeating cyclic structure characteristic of deep surge. During the deep surge portion of the prediction, pressure fluctuations are compared with measurements at the corresponding compressor inlet and outlet transducer locations, where the amplitudes and frequencies exhibit excellent agreement. The predicted flow field throughout the compression system is studied in detail during operation in deep surge, in order to characterize the unsteady and highly 3D structures present within the impeller, diffuser, and compressor inlet duct. Key observations include a core flow region near the axis of the inlet duct, where the flow remains in the forward direction throughout the deep surge cycle. The dominant noise generation occurs at the fundamental surge frequency, which is near the Helmholtz resonance of the compression system, along with harmonics at integer multiples of this fundamental frequency.

Application of metasurface-enhanced infra-red spectroscopy to distinguish between normal and cancerous cell types.

Fourier transform infrared (FTIR) spectra of biological cells can reveal clinically important information about cells' composition, including their normal or cancerous status. The recently emerged diagnostic technique of spectral cytopathology (SCP) combines FTIR with multivariate statistical analysis to detect cell abnormalities, differentiate between cell types, and monitor disease progression. We demonstrate a new variant of SCP, a metasurface-enhanced infrared reflection spectroscopic cytopathology (MEIRSC) that utilises judiciously designed plasmonic metasurfaces to localize and enhance the evanescent field near the cell's membrane, and to carry out spectroscopic interrogations of the cells attached to the metasurface using reflected infrared light. Our findings indicate that the MEIRSC approach enables us to differentiate between normal and cancerous human colon cells. The sensitivity of MEIRSC is such that a very small (about 50 nm deep) portion of the cell can yield valuable diagnostic information.

Muscle spindles of the rat sternomastoid muscle.

The sternomastoid (SM) muscle in rodents presents a peculiar distribution of fiber types with a steep gradient from the ventral, superficial, white portion to the dorsal, deep, red region, where muscle spindles are restricted. Cross section of the medial longitudinal third of the rat SM contains around 10,000 muscle fibers with a mean diameter of 51.28±12.62 (μm +/- SD). Transverse sections stained by Succinate Dehydrogenase (SDH) reaction clearly presents two distinct regions: the dorsal deep red portion encompassing a 40% cross section area contains a high percentage of packed SDH-positive muscle fibers, and the ventral superficial region which contains mainly SDH-negative muscle fibers. Indeed, the ventral superficial region of the rat SM muscle contains mainly fast 2B muscle fibers. These acidic ATPase pH 4.3-negative and SDH-negative 2B muscle fibers are the largest of the SM muscle, while the acidic ATPase pH 4.3-positive and SDH-positive Type 1 muscle fibers are the smallest. Here we show that in thin transverse cryosections only 2 or 3 muscle spindle are observed in the central part of the dorsal deep red portion of the SM muscle. Azan Mallory stained sections allow at the same time to count the spindles and to evaluate aging fibrosis of the skeletal muscle tissue. Though restricted in the muscle red region, SM spindles are embedded in perimysium, whose changes may influence their reflex activity. Our findings confirm that any comparisons of changes in number and percentage of muscle spindles and muscle fibers of the rat SM muscle will require morphometry of the whole muscle cross-section. Muscle biopsies of SM muscle from large mammals will only provide partial data on the size of the different types of muscle fibers biased by sampling. Nonetheless, histology of muscle tissue continue to provide practical and low-cost quantitative data to follow-up translational studies in rodents and beyond.

New profiling and mooring records help to assess variability of Lake Issyk-Kul and reveal unknown features of its thermohaline structure

Abstract. This article reports the results of three field campaigns conducted in Lake Issyk-Kul in 2015, 2016, and 2017. During the campaigns, CTD profiling and water sampling were performed at 34 locations all over the lake. A total of 75 CTD profiles were obtained. Some biogeochemical and thermohaline parameters at the lake surface were also mapped at high horizontal resolution along the ship's track. In addition, thermistor chains were deployed at three mooring stations in the eastern littoral region of the lake, yielding 147-day-long records of temperature data. The measurements revealed that – while the thermal state of the active layer, as well as some biogeochemical characteristics, were subject to significant interannual variability mediated by atmospheric forcing – the haline structure of the entire lake was remarkably stable at the interannual scale. Our data do not confirm the reports of progressive warming of the deep Issyk-Kul waters as suggested in some previous publications. However, they do indicate a positive trend of salinity in the lake's interior over the last 3 decades. A noteworthy newly found feature is a weak but persistent salinity maximum below the thermocline at a depth of 70–120 m, from where salinity slightly decreased downwards. The data from the moored thermistor chains support the previously published hypothesis about the significant role of the submerged ancient riverbeds on the eastern shelf in advecting littoral waters into the deep portion of the lake during differential cooling period. We hypothesize that the less saline littoral water penetrating into the deep layers due to this mechanism is responsible for the abovementioned features of salinity profile, and we substantiate this hypothesis by estimates based on simple model assumptions.