Laminar Layer Research Articles

Feature-dependent intrinsic functional connectivity across cortical depths in the human auditory cortex

Frequency preference and spectral tuning are two cardinal features of information processing in the auditory cortex. However, sounds should not only be processed in separate frequency bands because information needs to be integrated to be meaningful. One way to better understand the integration of acoustic information is to examine the functional connectivity across cortical depths, as neurons are already connected differently across laminar layers. Using a tailored receiver array and surface-based cortical depth analysis, we revealed the frequency–preference as well as tuning–width dependent intrinsic functional connectivity (iFC) across cortical depths in the human auditory cortex using functional magnetic resonance imaging (fMRI). We demonstrated feature-dependent iFC in both core and noncore regions at all cortical depths. The selectivity of frequency–preference dependent iFC was higher at deeper depths than at intermediate and superficial depths in the core region. Both the selectivity of frequency–preference and tuning–width dependent iFC were stronger in the core than in the noncore region at deep cortical depths. Taken together, our findings provide evidence for a cortical depth-specific feature-dependent functional connectivity in the human auditory cortex.

Microstructual and mechanical studies of the dissimilar tabular joints of Incoloy alloy 825 and AISI 316 stainless steel

ABSTRACT In this work, dissimilar welding of Incoloy alloy 825 and AISI 316 stainless steel tubes is experimentally investigated using gas metal arc welding process. For this purpose, different filler metals such as stainless steel 308, stainless steel 309, stainless steel 316 and Inconel 82 are employed for joining of Incoloy alloy 825 and AISI 316 stainless steel tubes. The results show that during tensile tests, fracture occurred in all weldments in the heat-affected zone (HAZ) of stainless steel 316. Also, it is concluded that dissimilar welds produced by stainless steel 309 filler metal have the maximum tensile strength while the lowest strength is obtained with Inconel 82 filler metal. The results of average hardness prove that the dissimilar joint with filler metal say stainless steel 309 and filler metal say Inconel 82 have maximum and minimum values of average hardness in the weld metal, respectively. The results show a considerable unmixed zone (UMZ) in the form of laminar layers between filler 82 weld metal and the Incoloy 825 base metal along the welding line. In addition, considerable UMZ is seen in the interface of the weld metal/AISI 316 base metal, but more grain growth occurred in the AISI 316 HAZ due to the temperature increase during various welding passes. It is indicated that there is a very narrow UMZ between the 309 weld metal and Incoloy 825 base metal; however, no considerable UMZs can be observed in the AISI 316 base metal.

Visual experimental investigations of string cavitation and residual bubbles in the diesel nozzle and effects on initial spray structures

In this article, optical experiments on string cavitation and residual bubbles inside the real-size transparent tapered diesel nozzle and near-nozzle spray structures were performed based on a high-pressure common rail fuel injection system with a high-speed camera. The tapered nozzle which has high flow efficiency with weak or even no geometric cavitation has been widely used in commercial injectors, while there still exists string cavitation which may also influence the in-nozzle flow and subsequent spray. This article put focus on the tapered nozzle and the result indicated that the in-nozzle string cavitation provided a reasonable explanation for the two bumps of spray cone angles during the opening and closing stages of needle of real diesel engine injection processes. The suction and compression of air bubbles at the start and end stages of injection processes, and the various shot-to-shot near-nozzle spray patterns were captured and analyzed. These different near-nozzle spray patterns were attributed to the distribution of residual bubbles inside the nozzle orifice. The residual bubbles were survived from the last injection or sucked into the nozzle during needle opening stages. Stagnant bubbles were compressed and then accelerated the residual fuel which was close to the injector tip, leading to the formation of mushrooms. This study confirmed that the initial mushroom and the tail were generated by the interactions between the residual/sucked bubbles and the residual/initial fuel, and the leading mushroom was incurred by the combination of the transverse expansion of the jet and the laminar layer theory. This work pointed out and analyzed the new sources of the cycle-to-cycle variation of air/fuel mixture and spray.

Onset of centrifugal instability at a rotating cylinder in a stratified fluid

In this experimental note, we consider the centrifugal instability of a laminar shear layer, generated by the impulsive start of the rotation of a circular solid cylinder about its vertical axis immersed in a linearly stratified fluid. The flow is determined by the Reynolds number, Re, based on the cylinder rotation rate and the cylinder radius, and the Froude number, Fr, represented by the ratio of the rotation frequency Ω over the buoyancy frequency N. The onset of the instability starts when the boundary layer reaches a certain thickness. We show for this boundary layer that there is a transition from the centrifugally unstable regime to a wave-like regime at Fr ≈ 1 and a stable flow below a critical Reynolds number. We focus on the centrifugally unstable regime Fr⪆1, for which the onset time and wavelength are predicted by scaling laws that depend on the Reynolds number. Agreement with the theoretical prediction of Kim and Choi [“The onset of instability in the flow induced by an impulsively started rotating cylinder,” Chem. Eng. Sci. 60, 599–608 (2005)] in a homogeneous fluid confirms that the instability of this boundary layer is not modified by the presence of stratification. These results therefore show that the centrifugal instability of the spin-up boundary is dominated by inertial motions, suggesting that close lateral boundaries, as in thin-gap stratified Taylor-Couette flow, increase the effects of buoyancy on the instability and wavelength.

Large-eddy simulation of airfoil flow near stall condition at Reynolds number 2.1 × 106

This paper investigates an airfoil flow involving a turbulent transition and separations near the stall condition at a high Reynolds number Rec = 2.1 × 106 (based on the freestream velocity and the airfoil chord) and provides the wall-resolved large-eddy simulation (LES) database for near-wall models in LES. The present results are compared with the existing experimental and computational data. The wall-resolved LES with the finest mesh (Δξ+,Δη+,Δζ+: chordwise, wall normal, spanwise ≲25, 0.8, 13) and the widest spanwise extent (approximately 5% of the chord length) resolves the key phenomena of the flow (i.e., laminar separation, transition to turbulence, turbulent reattachment, turbulent boundary layer development, and turbulent separation) and well predicts turbulence statistics. The present LES also clarifies unsteady flow features associated with shear-layer instability: the high frequency unsteadiness of St ≃ 130 (based on the freestream velocity and the airfoil chord) at the laminar separation bubble near the leading edge and low frequency unsteadiness of St ≃ 2 at the turbulent separation near the trailing edge. The characteristic frequencies can be scaled to 0.035 and 0.033 by the local momentum thickness and the shear layer velocity which are similar to the natural frequency of the laminar and turbulent shear layer, respectively. With regard to the near-wall modeling in LES, the obtained database indicates that the pressure-gradient term in the mean streamwise-momentum equation is not negligible at the laminar and turbulent separated regions. This fact suggests that the widely used equilibrium wall model is not sufficient, and the inclusion of the pressure-gradient term is necessary for wall modeling in LES of such an airfoil flow. Additionally, influences of computational mesh resolution and spanwise extent on the computational results in wall-resolved LES are investigated.

Turbulent Transport by Diffusive Stratified Shear Flows: From Local to Global Models. II. Limitations of Local Models

This paper continues the systematic investigation of diffusive shear instabilities initiated in Part I of this series. In this work, we primarily focus on quantifying the impact of non-local mixing, which is not taken into account in Zahn's mixing model \citep{Zahn92}. We present the results of direct numerical simulations in a new model setup designed to contain coexisting laminar and turbulent shear layers. As in Part I, we use the Low P\'eclet Number approximation of \citet{Lign1999} to model the evolution of the perturbations. Our main findings are twofold. First, turbulence is not necessarily generated whenever Zahn's nonlinear criterion \citep{Zahn1974} $J{\rm Pr} < (J{\rm Pr})_c$ is satisfied, where $J=N^2/S^2$ is the local gradient Richardson number, ${\rm Pr} = \nu/ \kappa_T$ is the Prandtl number, and $(J{\rm Pr})_c \simeq 0.007$. We have demonstrated that the presence or absence of turbulent mixing in this limit hysteretically depends on the history of the shear layer. Second, Zahn's nonlinear instability criterion only approximately locates the edge of the turbulent layer, and mixing beyond the region where $J{\rm Pr} < (J{\rm Pr})_c$ can also take place in a manner analogous to convective overshoot. We found that the turbulent kinetic energy decays roughly exponentially beyond the edge of the shear-unstable region, on a lengthscale $\delta$ that is directly proportional to the scale of the turbulent eddies, which are themselves of the order of the Zahn scale (see Part I). Our results suggest that mixing by diffusive shear instabilities should be modeled with more care than is currently standard in stellar evolution codes.

Superficial Fascia in the Cheek and the Superficial Musculoaponeurotic System.

The origins and validity of the term "superficial musculoaponeurotic system" (SMAS) is reviewed. Gray stated the superficial fascia connects the skin with the deep or aponeurotic fascia and consists of fibro-areolar tissue. Hollinshead wrote superficial fascia exists throughout the body and contains a variable amount of fat. In the head and neck, it encloses voluntary muscles in its deep portion. Skoog found superficial fascia was fixed to the dense, deep fascia by fibrous adhesions in the temporal, preauricular, and parotid area. Mitz stated "There is a 'superficial muscular and aponeurotic system' (SMAS) in the parotid and cheek areas." SMAS has an intimate relationship with the entire superficial fascia of the head and neck and divides the subcutaneous fat into 2 layers. Wassef found a continuous fibromuscular layer at the deep limit of the "subcutis," which corresponded to the "superficial fascia." Nakajima reported the subcutaneous adipofascial tissue was made up of 2 adipofascial layers. Macchi found 2 different fibroadipose connective layers bounded to the laminar connective tissue layer (SMAS). In the cheek, Hwang found horizontal fibrous connective tissues (membranous layer of superficial fascia) divided the superficial fascia into the superficial fatty layer and the deep fatty layer. Recently, Mitz explained the reason for the term SMAS. The "musculo+aponeurotic" component is based on histology of muscle cells, including the risorius, in the same structure to be surgically consistent. The aponeurotic cells belong to the same surgical layer. SMAS is not sufficient to replace the old term "superficial fascia" of the cheek area.

Quantitative Assessment of Retina Explant Viability in a Porcine Ex Vivo Neuroretina Model.

Given that porcine and human retinas have similar structures and characteristics, ex vivo culture of porcine neuroretina provides an attractive model for studying mechanisms of human retinal injury and degenerative disease. Here, we describe the method that was used to establish and characterize an adult porcine retina culture system as a rapid screening tool for retinal survival in real time. Neuroretina explants 8 mm in diameter were harvested from adult swine and cultured on porous cell culture inserts with adjustable heights. Retina explant viability was evaluated at 1, 4, 7, 11, and 14 days of culture using a resazurin-based metabolic assay. The explants were analyzed morphologically through immunohistochemistry for glial activation and apoptosis. Morphometric analysis was also performed on hematoxylin and eosin-stained retina sections from each time point. The viability of retina explants gradually decreased over time in culture. The laminar structure of the neuroretina was well preserved during the first 7 days. However, by day 14, most explants showed significant loss of cells in each laminar layer and obvious thinning. Overall, the progressive loss of retinal lamination and thickness, and increase in apoptotic nuclei with activated hypertrophic Müller cells were well correlated with the metabolic activity of the ex vivo neuroretina explants. This study was the first report to describe the use of a high-throughput and quantitative method for monitoring retina explant viability in real time. Ex vivo neuroretina cultures closely mimic the functional dynamics of the organ, and can be used efficiently to screen novel therapeutics for retinal neurodegenerative disease.

Impact of affected lymph nodes on long-term outcome after surgical therapy of alveolar echinococcosis.

Alveolar echinococcosis (AE) is a life-threatening helminthic disease. In humans, AE mostly affects the liver; the regional hepatic lymph nodes may be involved, indicating dissemination of AE from the liver. To achieve complete removal of the disease, enlarged hepatic lymph nodes may be resected during surgical treatment. We evaluated the frequency of affected lymph nodes by conventional microscopic and immunohistochemical analyses including detection of small particles of Echinococcus multilocularis (spem). Furthermore, we analyzed the association of resection of enlarged and affected lymph nodes with long-term outcome after surgical therapy of patients who underwent surgery with curative intent. We identified 43 patients who underwent hepatic surgery with curative intent with lymph node resection for AE. We analyzed the cohort for the manifestation of the parasite in the resected lymph nodes by conventional histology and by immunohistochemistry and compared these data with the further course of AE. Microscopically infected lymph nodes (laminar layer visible) were found in 7 out of these 43 patients (16%). In more than three quarters (25/32) of all specimens investigated, lymph nodes showed spems when stained with antibody against Em2G11, a monoclonal antibody specific for the Em2 antigen of the Echinococcus multilocularis metacestode. Most frequently, lymph nodes were resected due to enlargement. The median size of microscopically affected lymph nodes was 2cm (range, 1.2 to 2.5cm), the median size of immunohistochemically and non-affected lymph nodes was 1.3cm each (range, "small" to 2.3 or 2.5cm, respectively). Median follow-up was 8years for all patients, 5years for patients with lymph node resection, and 4years for patients with infested lymph nodes. Overall, recurrent disease was seen in ten patients (10/109; 9%) after a median period of 1.5years (range, 4months to 4years). None of the seven patients with conventionally microscopically affected lymph nodes suffered from recurrent disease. One patient with negative resected nodes and one patient with spems showed recurrent disease after 4 and 35months, respectively. Lymph node involvement in AE is frequent, particularly when evaluated by immunohistochemical examination of lymph nodes with the monoclonal antibody Em2G11. Affected lymph nodes tend to be larger in size. Lymph node involvement is not associated with recurrent disease and therefore warrants further analysis of the biological significance of lymph node involvement.

Determination of microcharacteristics of air flow in the nasal cavity during breathing

The aim of the work is to determine the degree of traumatization of the mucous membrane of the nasal cavity by turbulent air flow. It should be noted that it is especially important to determine in the narrowing of the nasal cavity (olfactory gap), where the mucous membrane is subjected to drying with increasing turbulence of the air flow. Achieving this goal will increase the effectiveness of diagnosis and treatment of respiratory and olfactory disorders and will help to identify the pathogenesis of chronic rinological diseases. An important characteristic of nasal breathing is the distribution of air flow rates along the sections of the nasal cavity. When analyzing the existing approaches, it was determined that the main method of studying the aerodynamics of the nasal cavity is rhinomanometry. However, there is not always a clear correlation between anatomical and functional indicators, as well as subjective feelings of the patient and rhinomanometric data. The passage of air through the upper nasal passage ensures the delivery of odorivector molecules to sensitive areas of the olfactory analyzer. The study of the characteristics of the air flow in the upper nasal passage allows us to determine the boundaries of the near-wall laminar air sublayer and to study nasal aerodynamics at the micro level. Turbulent flow contributes to the excessive drying of the mucous membrane of the nasal cavity, leading to its morphological rearrangement towards the subatrophic process. It was found out that the thickness of the laminar layer is of the order of 1 mm, therefore the protuberances of the mucosa are subjected to drying with increasing turbulence of the flow at the sites of narrowing of the nasal cavity (olfactory gap). The prospect of work is the study of the characteristics of the boundary layer in typical pathologies in various respiratory regimes, which will improve the efficiency of diagnosis and treatment of respiratory and olfactory disorders and will help to identify the pathogenesis of chronic rinological diseases.

Morfoanatomía de las plántulas de dos especies de lupinos graníferos: Lupinus albus y L. angustifolius (Fabaceae, Faboideae)

The morphoanatomy of seedlings of two cultivated grain lupines is described and compared ( Lupinus albus L. and L. angustifolius L.). To obtain the seedlings, 60 seeds of each species were sown in terrines with a coarse sand substrate. After 20 days from sowing, 15 seedlings were selected and the lengths of hypocotyl, epycotyl were measured as well as, the length and width of leaflets, which showed significant differences except in the lengths of the leaflets. Optical microscope slides were done for the epidermis and cross-sections of primary root, hypocotyl, epycotyl, petiole and leaflet, the sections were analyzed, illustrated and photographed. Both species share the same structure of diarch root, glabrous adaxial face and anfistomatics characteristics with anomocytic stomata in leaflets epidermal layers. The most noticeable differences between the species seedlings are the presence of a laminar collenchyma layer and the larger number of vascular bundles in the hypocotyl and epycotyl of L. angustifolius and a starchy layer sheath in the hypocotyl of L. albus . The cordate form and the two lobes emerging from a center channel in the petiole of L. angustifolius, reaffirm other morphological similarities with the species L. gibertianus . The major differences in the leaflets are the width and the structure of the mesophyll which is dorsiventral in L. albus and is isobilateral in L. angustifolius . The structure of an epitricopodium in tricelular trichomes are described for the first time for the genus Lupinus . The anatomical structures were com- pared and discussed with those of other species of the genus, with environmental conditions and with modifications by plant breeding. This work serves as a basic knowledge for further research to find if there are relationship between support tissues and transport system with the plant protection strategies against pathogen infections and water stress.

Differential gene regulatory plasticity between upper and lower layer cortical excitatory neurons

Neocortical projection neurons consist of intracortical connected upper layer (UL, layer II–IV) neurons and subcortical connected lower layer (LL, layer V–VI) neurons. Afferent activity from the thalamus regulates layer-specific gene expression during postnatal development, which is critical for the formation of proper neocortical cytoarchitecture. Here, we show that activity-dependent gene regulation is confined to UL cortical neurons, but not LL neurons, and that this distinction is likely due to epigenetic modifications of chromatin. We found that the immediate early genes (IEGs), EGR1 and c-FOS, are downregulated in all cortical laminar layers in the absence of afferent activity in vivo. Transcriptional assays demonstrated that EGR1 and c-FOS are able to bind to the promoters of UL- and LL-specific genes to induce transcription. Furthermore, we discovered that LL neurons express higher levels of heterochromatin markers, such as H3K9m3 and H4K20m3, compared to UL neurons. Our results suggest that differential epigenetic modifications of chromatin is an intrinsic mechanism that underlies the different sensitivities of cortical neurons to activity-dependent gene regulation.

A Classification of Clay‐Rich Subaqueous Density Flow Structures

This study presents a classification for subaqueous clay‐laden sediment gravity flows. A series of laboratory flume experiments were performed using 9%, 15%, and 21% sediment mixture concentrations composed of sand, silt, clay, and tap water, on varying bed slopes of 6°, 8°, and 9.5°, and with discharge rates of 10 and 15 m3/hr. In addition to the characteristics of the boundary and plug layers, which have been previously used for the classification of open‐channel clay‐laden flows, the newly presented classification also incorporates the treatment of the free shear layer. The flow states within the boundary and free shear layers were established using calculation of the inner variable, self‐similarity considerations, and the magnitude of the apparent viscosity. Based on the experimental observations four flow types were recognized: (1) a clay‐rich plug flow with a laminar free shear layer, a plug layer, and a laminar boundary layer, (2) a top transitional plug flow containing a turbulent free shear layer, a plug layer, and a laminar boundary layer, (3) a transitional turbidity current with a turbulent free shear layer, no plug layer, and a laminar boundary layer, and (4) a fully turbulent turbidity current. A connection between the emplaced deposits and the relevant flow types is drawn and it is shown that a Froude number, two Reynolds numbers, and a dimensionless yield stress parameter are sufficient to associate an experimental flow type with a natural large‐scale density flow.

Incorporating attapulgite nanorods into graphene oxide nanofiltration membranes for efficient dyes wastewater treatment

Graphene oxide/attapulgite (GO/APT) composite membranes were successfully fabricated by the vacuum-assisted filtration for efficient dyes wastewater treatment. By characterization of FTIR, XPS, Raman, XRD and FESEM, APT nanorods were confirmed to be incorporated into GO laminar layers via grafting modification, which would influence GO interlayer distance (d-spacing), membrane surface microstructure (laminate morphology, structure, and hydrophilicity) and even water separation performance. Comparison of those of pristine GO membrane, the calculated d-spacing of GO/APT membranes gradually increased from 0.90 nm to 1.07 nm, while water contact angles decreased from 71.0° to 43.3° with the increasing APT/GO ratios. Moreover, GO/APT membranes exhibited rough hierarchical microstructure and higher surface hydrophilicity, which was in conjunction with larger interlayer spacing to synergistically improve separation performance. The water permeated flux increased from 3.4 of pristine GO membrane to 13.3 L m−2 h−1 of GO/APT membrane with preserving high rejection nearly to 100% for 7.5 mg L−1 Rh B wastewater under optimized conditions. Similarly, membrane thickness, dye concentrations and separating species in feed solutions were also found to affect membrane separation performance. Dye molecules were efficiently rejected through GO/APT nanofiltration membranes by the synergistic separation mechanism: size exclusion effect because of the unimpeded water channels formed into 3D network laminate structure, and electrostatic interactions between the oxygen-containing functional groups on membrane surface and charged molecules. Such these GO/APT membranes demonstrated efficiently separation properties and thus provided new insight into the potential applications in water purification and dyes wastewater treatment.

Impacts of variable thermal conductivity on stagnation point boundary layer flow past a Riga plate with variable thickness using generalized Fourier’s law

Abstract This article explores the problem of two-dimensional, laminar, steady and boundary layer stagnation point slip flow over a Riga plate. The incompressible upper-convected Maxwell fluid has been considered as a rheological fluid model. The heat transfer characteristics are investigated with generalized Fourier’s law. The fluid thermal conductivity is assumed to be temperature dependent in this study. A system of partial differential equations governing the flow of an upper-convected Maxwell fluid, heat and mass transfer using generalized Fourier’s law is developed. The main objective of the article is to inspect the impacts of pertinent physical parameters such as the stretching ratio parameter ( 0 ⩽ A ⩽ 0.3 ) , Deborah number ( 0 ⩽ β ⩽ 0.6 ) , thermal relaxation parameter ( 0 ⩽ γ ⩽ 0.5 ) , wall thickness parameter ( 0.1 ⩽ α ⩽ 3.5 ) , slip parameter ( 0 ⩽ R ⩽ 1.5 ) , thermal conductivity parameter ( 0.1 ⩽ δ ⩽ 1.0 ) and modified Hartmann number ( 0 ⩽ Q ⩽ 3 ) on the velocity and temperature profiles. Suitable local similarity transformations have been used to get a system of non-linear ODEs from the governing PDEs. The numerical solutions for the dimensionless velocity and temperature distributions have been achieved by employing an effective numerical method called the shooting method. It is seen that the velocity profile shows the reduction in the velocity for the higher values of viscoelastic parameter and the thermal relaxation parameter. In addition, to enhance the reliability at the maximum level of the obtained numerical results by shooting method, a MATLAB built-in solver bvp4c has also been utilized.

Tunable semi-permeability of graphene-based membranes by adjusting reduction degree of laminar graphene oxide layer

Membrane-based water reuse and desalination technologies have been increasingly popular as an alternative water resource for mitigating global water scarcity. However, intrinsic limitations of conventional membranes restrict a further advance in membrane-based technologies. Recently, laminar-structure graphene oxide (GO) membranes fabricated by staking GO nanoplatelets have been emerging as a new water purification membrane with overcoming the conventional membrane limitations because of ultra-fast water permeation and precise molecular sieving capability based on ultra-low friction and well-defined nanochannels; to apply laminar GO membranes for ion removal such as desalination, tuning size of GO nanochannels within a sub-nanometer range is required. Herein, we adjusted reduction degree of GO laminates via varying exposure time to hydroiodic acid steam to control the size of GO nanochannels in a sub-nanometer range. Control of the hydroiodic acid vapor exposure time is a facile way to tune the nanochannel size in a sub-nanometer, and consequentially monovalent ion rejection rate can be handled.

Evolution of turbulence through a broadened preheat zone in a premixed piloted Bunsen flame from conditionally-averaged velocity measurements

This work assesses two hypotheses that predict how turbulence properties vary within premixed turbulent flames that lie in the regime of Broadened Preheat-Thin Reaction layers. There have been few prior measurements describing flames in this regime. The authors previously found that very broad preheat layers were achieved for turbulence levels (u′/SL) up to 243. Surprisingly, the reaction layer thickness did not increase, despite having Kolmogorov scales smaller than the laminar reaction layer thickness. A first hypothesis is that the turbulence decays in the preheat layer (as the temperature rises and viscous forces increase), so that the reaction layer sees only a small fraction of the initial turbulence. It follows that this turbulence decay might be responsible for the observed non-linear bending of the curve of turbulent burning velocity versus turbulence level. A second hypothesis is that the total turbulent kinetic energy does not decrease significantly in the preheat zone; instead, the small eddies decay and cause the integral scale to increase. Conditional averages are required to assess these two hypotheses. Fluorescence imaging identified the reaction zone boundary and particle image velocimetry diagnostics were applied simultaneously. The velocity measurements were conditioned on η, the distance to the upstream boundary of the reaction zone in each image. Conditioned measurements of turbulent kinetic energy, average eddy rotational velocity, strain rate, enstrophy, and integral length scale were computed through the flame. Results indicate that the turbulence level does not decrease within the broad preheat layers, and therefore the first hypothesis is not valid. In fact, the turbulence level within the entire burner core does not vary appreciably. However, the second hypothesis was supported by the measurements, since the integral scale increased by 50% across the preheat layer. The total turbulent kinetic energy did not decrease significantly. One explanation for this result is that small eddies are dissipated in the preheat zone.

Interoception and the Neurovisceral Axis as a Modal Basis for Computational Neuroecology

The defining parameters of neuroecology stand to benefit from a phenomenological expansion that includes the role of affect qua interoception as entailing a multimodal storehouse for specialized signal processing and brain architecture within the neurovisceral axis. The relationship between the gut and the brain represents an integral axis of communication drawing from the ecosystem of the microbiome as an environment for nerve-cell processes reflecting our habits of living and the influence of the luminal environment in higher-ordered cognition. This is shown to apply in both feedforward and inferential models of interoception. A surplus of evidence in recent years indicates that interoception and interoceptive awareness play a key role in influencing adaptive behavioral strategies, cognition, homeostatic regulation, decision-making, social relations and action. The groundwork for this expansion has already been positioned by preliminary efforts to offer a physiological basis for computational neuroecology and emotion qua somatic markers. Building off of their maiden report, this paper develops the richer neuroscientific landscape underwriting somatic markers in the context of the neurovisceral axis qua interoception and biological intuition. In the process we encounter an evolutionarily-rare and morphologically-specialized type of neuron conjectured to provide an advantage for social processing that eclipses the rudimentary notion of somatic markers, alone, and thereby enriches the descriptive landscape of neuroecological phenomena. Finally, we examine the inherent signal processing dynamics in cortical laminar layers as rendered in a newly-fashioned predictive coding account of interoception as a “limbic workspace theory” that interfaces with sensory signals between agranular and granular cells. Advances in predictive coding models and the free-energy principle stand poised to provide a unified model of neural signal processing encompassing sensory coding as well as adaptation in neurons, mood and behavior.The incorporation of interoceptive inference sheds critical light on anticipatory (feedback) signal-processing mechanisms in the brain. This suggests that an incorporation of interoceptive affect-in combination with cognition and adaptation-will shed critical light on further efforts to organize the driving epistemic structure and phenomenology associated with neuroecology.

Nanostructured laminar tungsten alloy with improved ductility by surface mechanical attrition treatment

A nanostructured laminar W-La2O3 alloy (WL10) with improved ductility was prepared using a surface mechanical attrition treatment (SMAT). φ1.5 mm ZrO2 WL10 balls subjected to SMAT (called φ1.5 mm ZrO2 ball SMATed WL10) samples possess the best surface profile and excellent integrated mechanical properties (the ductile-brittle transition temperature (DBTT) value decreases by approximately 200 °C, and the bending strength decreases by 100 Mpa). A highly dense group of laminates was detected near the surface of the φ1.5 mm ZrO2 ball SMATed WL10 sample. The SMATed WL10 laminates were composed of a micro-grain layer, an ultrafine-grain layer and a nanosized-grain layer. The nanostructured laminar surface layer of the φ1.5 mm ZrO2 ball SMATed WL10 sample is approximately 1–2 μm. The top surface of the WL10 plates with and without the SMAT process possesses residual compressive stress of approximately −883 MPa and −241 MPa, respectively, in the y direction and −859 MPa and −854 MPa, respectively, in the x direction. The SMAT process could be a complementary method to further improve the toughness of tungsten-based materials.

Abstract 128: LRP1 Deletion in Smooth Muscle Cells of the Outer Aortic Media Promotes Angiotensin II-induced Thoracic Aortic Aneurysm

Objective: Low-density lipoprotein receptor-related protein 1 (LRP1) is a multifunctional protein that is linked to several vascular pathologies. LRP1 deletion in smooth muscle cells (SMCs) accelerates angiotensin II (AngII)-induced thoracic aortic aneurysm (TAA). In association with TAA formation, there is medial thickening that is characterized by a transmural gradient in which pathology progressively increases from lumen to adventitial aspect. We hypothesized that deletion of LRP1 in the outer medial layers of the proximal thoracic aorta has a pivotal role in the pathogenesis of TAA. The aim of this study was to determine whether LRP1 deletion in the outer media accelerates AngII-induced TAA formation. Methods and Results: SMCs in the outer media of the ascending aorta are derived from the second heart field, as demonstrated by lineage tracing studies using Cre under the control of Mef2c. Therefore, we used Mef2c-driven Cre to delete LRP1 in SMCs of the outer medial layers. Female LRP1 flox/flox mice were bred to male Mef2c-Cre1/0 mice to generate study mice. We first confirmed LRP1 deletion in Cre1/0 mice by both immunostaining and Western blot. LRP1 was expressed ubiquitously across smooth muscle cells of all aortic medial layers in Cre 0/0 mice. In mice expressing Mef2c-Cre, aortic LRP1 protein was detected only in SMCs of the inner laminar medial layers. Western blotting demonstrated LRP1 protein abundance in Cre expressing mice was reduced by 43%. Saline or AngII (1,000 ng/kg/min) was infused by subcutaneous osmotic pumps for 28 days into 12 - 14 week-old male Cre0/0 and 1/0 mice. As expected, systolic blood pressure increased similarly in both AngII-infused Cre 0/0 and 1/0 mice compared to saline-infused mice. Aortic rupture occurred within 3 to 10 days after AngII infusion in 17% of AngII-infused Cre 0/0 mice, while LRP1 deletion in Cre 1/0 mice increased aortic rupture to 27%. Aortic diameter in the survivors was significantly increased in Cre1/0 mice compared to Cre0/0 mice. Histologically, elastin fragmentation was detected in the aorta of AngII-infused Cre 0/0 mice and greater in Cre1/0 mice. Conclusion: LRP1 in second heart field-derived SMCs of the outer media may play a critical role in the pathogenesis of TAA.