Scalloped Pattern Research Articles

Boucher-Neuhauser Syndrome: Chorioretinal Changes in a Single Case Over Time.

To describe chorioretinal changes in a single case of Boucher-Neuhauser Syndrome (BNHS) over 45 years of follow-up. Methods: Retrospective chart review was performed. Color fundus photography from 1977 to 2003 was obtained and digitized. Current fundus photography was obtained with widefield imaging. High-resolution spectral-domain optical coherence tomography (OCT) was performed. Genetic analysis was performed using an inherited retinal disorders panel. Results: Fundus examination demonstrated central chorioretinal atrophy with sclerotic choroidal vessels. Short posterior ciliary arteries became more prominent and tortuous over time. Mid-peripheral atrophy extends to the equator and demonstrates a scalloped pattern with islands of atrophy intervening with areas of normal retina. The far periphery remained minimally affected. High-resolution OCT demonstrated outer retinal atrophy and choriocapillaris loss. Genetic testing showed a homozygous variant for PNPLA6 and a heterozygous variant for TYRP1. Conclusion: Chorioretinal changes in BNHS vary in onset and severity. It is important to diagnose this condition in order to begin timely management of visual and systemic sequelae.

Emergence of tip singularities in dissolution patterns.

Chemical erosion, one of the two major erosion processes along with mechanical erosion, occurs when a soluble rock-like salt, gypsum, or limestone is dissolved in contact with a water flow. The coupling between the geometry of the rocks, the mass transfer, and the flow leads to the formation of remarkable patterns, like scallop patterns in caves. We emphasize the common presence of very sharp shapes and spikes, despite the diversity of hydrodynamic conditions and the nature of the soluble materials. We explain the generic emergence of such spikes in dissolution processes by a geometrical approach. Singularities at the interface emerge as a consequence of the erosion directed in the normal direction, when the surface displays curvature variations, like those associated with a dissolution pattern. First, we demonstrate the presence of singular structures in natural interfaces shaped by dissolution. Then, we propose simple surface evolution models of increasing complexity demonstrating the emergence of spikes and allowing us to explain at long term by coarsening the formation of cellular structures. Finally, we perform a dissolution pattern experiment driven by solutal convection, and we report the emergence of a cellular pattern following well the model predictions. Although the precise prediction of dissolution shapes necessitates performing a complete hydrodynamic study, we show that the characteristic spikes which are reported ultimately for dissolution shapes are explained generically by geometrical arguments due to the surface evolution. These findings can be applied to other ablation patterns, reported for example in melting ice.

About the role of the Hanratty correction in the linear response of a turbulent flow bounded by a wavy wall

Scallop patterns forming on erodible surfaces were studied historically using a linear analysis of the inner region of a turbulent boundary layer growing on a corrugated wall. Experimental observations show a phase shift between the shear stress at the wall and the wall oscillation that depends on the wavenumber. Anad hoccorrection applied to the turbulent closure and due to Hanrattyet al.(Thorsnesset al.,Chem. Engng Sci., vol. 33, issue 5, 1978, pp. 579–592; Abrams & Hanratty,J. Fluid Mech., vol. 151, issue 1, 1985, p. 443; Frederick & Hanratty,Exp. Fluids, vol. 6, issue 7, 1988, pp. 477–486) was systematically used to recover the reference experimental results. In this study, Reynolds-averaged Navier–Stokes (RANS) and direct numerical simulations (DNS) were performed and revealed the role of the Boussinesq assumption in the results obtained. We show that the Hanratty correction acts as a palliative to the misrepresentation of Reynolds stresses due to the use of the Boussinesq hypothesis. The RANS calculations based on a turbulence model using a second-order moment closure recovered the expected results obtained in the reference DNS calculations, in particular with respect to wall heat transfer. The analysis of these results highlights the critical importance of the anisotropy of the diagonal Reynolds stresses on the prediction of wall transfer under these conditions and their implication in the occurrence of scalloping.

Scalloped pattern deposition during the spreading and drying of polymer droplets.

Droplets containing polyvinylpyrrolidone (PVP) dissolved in ethanol display a distinctive scalloped pattern at the rim while spreading and drying on a high-energy surface. Two distinct spreading regimes are observed, leading to the formation of a thin film with a uniform height that extends from the original droplet. An experimental study indicates polymer accumulation at the edge containing trace water, resulting in a surface tension gradient across the droplet, enhancing the droplet's spreading. This fast-spreading film develops a ridge at the contact line and becomes unstable. The influence of evaporation within the droplet shows no significant effect on the wavelength of the instability. Instead, the magnitude of the surface tension gradient and the surface energy of the substrate emerge as the dominant factors influencing the instability. This observation is validated by saturating the environment surrounding the droplet with ethanol vapour to reduce evaporation or employing solvents with low vapour pressure. Additionally, PVP in ethanol droplets deposited on hydrophobic substrates demonstrate a stable and pinned contact line, contrasting the behaviour observed on high-energy surfaces. By identifying the critical overlap concentration of the polymer, the transitional threshold between the scalloped instability and ringlike morphology is determined. The scalloped instability can be suppressed by removing residual water from the solution, eliminating the surface tension gradient, indicating that Marangoni forces are the underlying cause of the observed instability. The long-wave evolution equation, assuming a constant Marangoni shear flow, accurately predicts the most unstable wavelength, demonstrating good agreement with experimental observations.

An In Silica Model for RPE Loss Patterns in Choroideremia.

PurposeTo use empirical data to develop a model of cell loss in choroideremia that predicts the known exponential rate of RPE loss and central, scalloped preservation pattern seen in this disease.MethodsA computational model of RPE loss was created in Python 3.7, which constructed an array of RPE cells clusters, binarized as either live or atrophic. Two rules were applied to this model: the background effect gave each cell a chance of dying defined by a background function, and the neighbor effect increased the chance of RPE cell death if a neighbor were dead. The known anatomic distribution of rods, RPE, choriocapillaris density, amacrine, ganglion, and cone cells were derived from the literature and applied to this model. Atrophy growth rates were measured over arbitrary time units and fit to the known exponential decay model. The main outcome measures: included topography of atrophy over time and fit of simulated residual RPE area to exponential decay.ResultsA background effect alone can simulate exponential decay, but does not simulate the central island preservation seen in choroideremia. An additive neighbor effect alone does not simulate exponential decay. When the neighbor effect multiplies the background effect using the rod density function, our model follows an exponential decay, similar to previous observations. Also, our model predicts a residual island of RPE that resembles the topographic distribution of residual RPE seen in choroideremia.ConclusionsThe pattern of RPE loss in choroideremia can be predicted by applying simple rules. The RPE preservation pattern typically seen in choroideremia may be related to the underlying pattern of rod density. Further studies are needed to validate these findings.

Effective permeability tensor of confined flows with wall grooves of arbitrary shape

Pressure and shear-driven flows of a confined film of fluid overlying a periodic one-dimensional topography of arbitrary shape are considered for prediction of the effective hydraulic permeability in the Stokes flow regime. The other surface confining the fluid may be a planar no-slip wall, an identically patterned wall, a free surface or a surface with prescribed shear. Analytical predictions are obtained using spectral analysis and the domain perturbation method under the assumption of small pattern size to pitch ratio. Using a novel decomposition of the channel height effects into exponentially and algebraically decaying components, a simple surface-metrology-dependent relationship which connects the eigenvalues of the effective permeability tensor is obtained. Two representative topographies are assessed numerically: the infinitely differentiable topography of a phase-modulated sinusoid which has multiple local extrema and zero crossings and the non-differentiable triangular-wave topography. Non-differentiability in the form of corners of triangular patterns and the cusps of scalloped patterns are not found to be an impediment to meaningful and numerically accurate asymptotic predictions of effective permeability and effective slip, contradicting an earlier suggestion from the literature. Several distinct applications of the theory to the friction-reduction and shear-stability performance of the recently developed lubricant impregnated patterned surfaces as well as to scalloped and trapezoidal drag-reduction riblets are discussed, with comparison to experimental data from the literature for the last application. Analytical approximations which have an extended domain of numerical accuracy are also proposed.

Preparation and formation mechanism of Al-Si/Al2O3 core-shell structured particles fabricated via steam corrosion

Abstract In this study, Al-Si/Al2O3 core-shell structured particles were fabricated via pressurized steam corrosion for 1 h followed by heating for 3 h at 1100 °C. After steam corrosion, a layer composed of disordered crystals covered the surfaces of the Al-Si alloy particles. After heating, Al-Si/Al2O3 core-shell structured particles with complete shells were prepared. The thickness of the shell was approximately 2 μm, and it enclosed the Al-Si alloy core. The shell exhibited excellent thermal stability because, even at 1100 °C, the mass gain ratio of the encapsulated particle was less than 0.5%. Scalloped patterns of alumina were formed by the oxidation of Al, which was inlaid through and upon the alumina shell. The shell formation mechanism suggested that the α-Al2O3 shell resulted from the combination of the decomposition of surface Al(OH)3 crystals and the oxidation of Al from the core.

Convection Initiation Resulting From the Interaction Between a Quasi‐Stationary Dryline and Intersecting Gust Fronts: A Case Study

AbstractThis study explores the convection initiation (CI) of a high‐impact squall line that occurred in central eastern China on 3 June 2009 based on observations and numerical modeling. The CI occurred in a scenario in which a set of intersecting gust fronts, organized in a distinct scalloped pattern, propagated toward an area of enhanced moisture produced by a near‐surface convergence line. This convergence line developed in a quasi‐stationary dryline zone. The dryline primed the preconvective environment by deepening the moist layer prior to the arrival of the intersecting gust fronts. The onset of CI occurred approximately 30 min after these intersecting gust fronts passed through the CI location, which was on the dry side of the dryline. Although these gust fronts acted as a strong signal for CI potential, CI did not occur along the entire length of the scalloped pattern of the intersecting gust fronts. The exact locations of the initiated convective cells were at the vertices of the scalloped pattern. An idealized simulation using a cloud model was conducted, demonstrating that the vertex regions were characterized by more favorable dynamical conditions for CI compared to the nonvertex regions along the scalloped outflow boundary. The greater CI probability over the vertex region was attributed to the greater magnitudes and larger vertical and horizontal extents of updrafts.

Automatic reinforcement from operant wheel-running undermines temporal control by fixed-interval schedules of reinforcement

The current study compared the development of response patterns for operant wheel-running and lever-pressing on fixed-interval schedules. Eleven female Long-Evans rats were exposed to fixed-interval (FI) 15-s, 30-s, and 60-s schedules with wheel revolutions as the operant behavior and sucrose solution as reinforcement. Subsequently, a lever was mounted in each wheel and rats responded on an FI-30 s schedule of sucrose reinforcement. Operant lever-pressing on average developed a scalloping pattern of low responding early in the reinforcement interval followed by an increase in pressing to the moment of reinforcement. In contrast, average operant wheel-revolutions peaked early in the reinforcement interval followed by a plateau, a pattern that did not change over sessions. Variation in the FI-schedule value (interval size) with operant wheel-running did not alter the pattern of running throughout the reinforcement interval, but merely parsed this pattern at different points. Cumulative records for the last session showed long postreinforcement pauses (PRP) for lever pressing. Wheel running, however, rose quickly after reinforcement and continued throughout the reinforcement interval. Overall and local wheel-running rates decreased and PRP duration increased as the interval size of the FI schedule increased. We propose that the automatic reinforcement generated by wheel running, but not lever pressing, provides an account of the poor temporal regulation of operant wheel-running in our study.

Numerical analysis of deposition frequency for successive droplets coalescence dynamics

A pseudopotential based multi-relaxation-time lattice Boltzmann model is employed to investigate the dynamic behaviors of successive droplets’ impact and coalescence on a solid surface. The effects of deposition frequency on the morphology of the formed line are investigated with a zero receding contact angle by analyzing the droplet-to-droplet coalescence dynamics. Two collision modes (in-phase mode and out-of-phase mode) between the pre-deposited bead and the subsequent droplet are identified depending on the deposition frequency. A uniform line can be obtained at the optimal droplet spacing in the in-phase mode (Δt* < 1.875). However, a scalloped line pattern is formed in the out-of-phase mode (Δt* > 1.875). It is found that decreasing the droplet spacing or advancing contact angle can improve the smoothness of line in the out-of-phase mode. Furthermore, the effects of deposition frequency on the morphology of the formed lines are validated to be applicable to cases with a finite receding contact angle.

Ovariectomy influences the circadian rhythm of locomotor activity and the photic phase shifts in the volcano mouse

Recently, the relationship between the circadian system and female reproduction has been of great interest; ovarian hormones can modify the amount and distribution of daily activity differently in rodent species. The volcano mouse Neotomodon alstoni is a species in which it is possible to study the circadian rhythm of locomotion, and it offers comparative information about the influence of ovaries on the circadian system. In this study, we used infrared crossings to compare free movement in intact and sham-operated or ovariectomized mice. We analyzed behavioral and endocrine changes related to the estrous cycle and locomotor circadian rhythm in free-running mice and photic phase shifting. Evidence shows that intact mice present a scalloped pattern of daily activity during the estrous cycle. In constant darkness, the ovariectomy reduces the total amount of activity, shortens the free-running circadian period of locomotion and increases photic phase shifts during the early subjective night. During entrainment, the ovariectomized mice increased the amplitude of total activity during the scotophase, and delay the time of activity onset. These results suggest that ovarian hormones in N. alstoni modulate the circadian rhythm of locomotor activity in a species-specific manner.

Chronic Vascular Arrest as a Predictor of Bevacizumab Treatment Failure in Retinopathy of Prematurity

To describe a pattern of retinopathy of prematurity (ROP) disease regression and chronic vascular arrest after intravitreal bevacizumab treatment that is not observed after peripheral laser ablation. Single-institution retrospective cohort study. Consecutive sample of 58 eyes in 30 patients treated for type 1 ROP. Initial treatment with either a single intravitreal injection of bevacizumab in off-label use (n= 33 eyes) or peripheral laser ablation (n= 25 eyes) as part of standard clinical care. There was bias in recommending off-label bevacizumab for smaller infants with type 1 ROP. Reactivation or persistence of ROP, as determined by clinical examination, fundus photography, and fluorescein angiography. All eyes treated initially with bevacizumab demonstrated irregular progression of the leading vascular edge in a stereotyped pattern, suggestive of scalloped regression. Recurrence, based on angiographic demonstration of leakage, or chronic vascular arrest, confirmed based on angiographic demonstration of peripheral ischemia, was noted in 30 eyes (91%) in the bevacizumab group, at a median interval of 14.9 weeks after injection (corrected gestational age, 49.3 weeks). Univariate logistic regression indicated that the need for rescue treatment was associated with decreased birth weight (odds ratio [OR],-0.007; P= 0.04) and age of initial treatment (OR,-0.35; P= 0.05), but not gender, race, or gestational age. Multivariate logistic regression indicated that only decreased birth weight (OR,-0.018; P= 0.04) was associated with need for rescue treatment. Treating ROP with intravitreal bevacizumab results in a characteristic scalloped regression pattern that is highly associated with treatment using biologic anti-vascular endothelial growth factor agents. The presence of this pattern in conjunction with chronic vascular arrest and peripheral retinal ischemia persisting beyond standard screening timelines has significant implications for the management of ROP. Fluorescein angiography is important in assessing vascular maturation in these infants.

Massive Ice Loss from the Mauna Loa Icecave, Hawaii

ABSTRACTWe provide the first detailed documentation of a lava tube cave with permanent ice on the Hawaiian Islands. “Mauna Loa Icecave” had been surveyed in 1978; we periodically visited the cave and monitored temperature, humidity, and ice levels from 2011 to 2014. Perennial ice still blocks the lava tube at the terminal end, but a previously present large ice floor (estimated 260 m2) has disappeared. A secondary mineral deposited on the cave walls is interpreted as the result of past sustained ice levels. Airflow measurements, scallop patterns in the ice, strong temperature and humidity variations, and ice volume fluctuations indicate ventilation of the cave, which suggests that additional ice loss could occur rapidly. The scientific potential of the ice record remains to be explored, before it is lost.

Effects of silicon via profile on passivation and metallization in TSV interposers for 2.5D integration

In this paper, the influences of profile factors on passivation and metallization in deep vias of Through Silicon Vias (TSV) interposer, such as taper angle, scallops and aspect ratio (AR), were investigated for 2.5D integration. The diameter of vias was scaled from 40μm to 100μm. Conventional Plasma Enhanced Chemical Vapor Deposition (PECVD) deposition and Physical Vapor Deposition (PVD) metallization processes were used. Slightly tapered vias was formed by Bosch process combination with isotropic etching. This investigation shows that the SiO2 passivation of the TSV vias with PECVD deposition is completely insensitive to the factors related to via profile. But the metallization with sputtering is quite sensitive to taper angle, scallops and AR. A good trade-off between passivation and metallization can be realized to fabricate the TSV interposer by controlling the taper angle in the range of 1–3°. The TSV vias with scalloping pattern is difficult to achieve the continuous and conductive metal layer. The continuous metal layer can be successfully achieved to realize the conductive interconnection with front-side multi-level metallization (MLM) layers in a maximal AR of ∼3 for tapered vias.

Development of Scallop Cut Type Damper Seal for Centrifugal Compressors

This paper deals with a new type of damper seal developed for a high-pressure centrifugal compressor. Honeycomb seals and hole pattern seals are popularly used as damper seals and provide superior rotordynamic damping characteristics. Honeycomb seals are expensive because the manufacturing process is complex. Hole pattern seals are easier to manufacture, but they are still expensive. Use of a scallop pattern is one way to reduce manufacturing cost and time. A new seal that has a scallop pattern and small teeth on the stator surface is proposed. This pattern is cut on the stator surface using a disk type tool. To estimate the rotordynamic coefficients of this new seal, a bulk flow model code that is based on a two-control-volume model developed by Matsuda for labyrinth seals was newly developed. This model uses the Hirs model for the viscous shear stresses. The friction factor coefficients for the rotor surface, the stator surface, and the surface between the two-control-volumes were determined by computational fluid dynamics (CFD) steady analysis. The rotordynamic coefficients can also be obtained by using CFD perturbation analysis. The high accuracy of the bulk flow model was demonstrated by comparing its results with CFD perturbation analysis results. In the perturbation analysis, the whirling motion was treated as a steady-state problem by using a rotating frame of reference. For the damper seal, the rotor surface and its neighboring region were treated with a rotating frame of reference and the neighboring region of the stator was treated with a stationary frame of reference. The damping property of the new seal was evaluated by conducting rotor stability tests using a high-pressure compressor with an electromagnetic exciter. The new seal equipped with swirl brakes was used for the balance piston of the compressor. Stability was evaluated by exciting the rotor during operation and identifying the eigenvalues of the rotor. The experimental results showed that the new seal increases damping. Comparison of the damping effect with calculations based on the bulk flow analysis showed good agreement.

Endocannabinoid-Dependent Modulation of Phasic Dopamine Signaling Encodes External and Internal Reward-Predictive Cues

The mesolimbic dopamine (DA) system plays an integral role in incentive motivation and reward seeking and a growing body of evidence identifies signal transduction at cannabinoid receptors as a critical modulator of this system. Indeed, administration of exogenous cannabinoids results in burst firing of DA neurons of the ventral tegmental area and increases extracellular DA in the nucleus accumbens (NAcc). Implementation of fast-scan cyclic voltammetry (FSCV) confirms the ability of cannabinoids to augment DA within the NAcc on a subsecond timescale. The use of FSCV along with newly developed highly selective pharmacological compounds advances our understanding of how cannabinoids influence DA transmission and highlights a role for endocannabinoid-modulated subsecond DAergic activation in the incentive motivational properties of not only external, but also internal reward-predictive cues. For example, our laboratory has recently demonstrated that in mice responding under a fixed-interval (FI) schedule for food reinforcement, fluctuations in NAcc DA signal the principal cue predictive of reinforcer availability – time. That is, as the interval progresses, NAcc DA levels decline leading to accelerated food seeking and the resulting characteristic FI scallop pattern of responding. Importantly, administration of WIN 55,212-2, a synthetic cannabinoid agonist, or JZL184, an indirect cannabinoid agonist, increases DA levels during the interval and disrupts this pattern of responding. Along with a wealth of other reports, these results illustrate the role of cannabinoid receptor activation in the regulation of DA transmission and the control of temporally guided reward seeking. The current review will explore the striatal beat frequency model of interval timing as it pertains to cannabinoid signaling and propose a neurocircuitry through which this system modulates interoceptive time cues.

Small bowel capsule endoscopy, a modern tool for celiac disease diagnosis - case presentation

Abstract Celiac disease is a clinically heterogeneous disease characterized by an inadequate immunological response when patients with specific genetic phenotypes are exposed to gluten. This article presents a case of a young woman diagnosed in Gastroenterology Department of “ St. Andrew Apostle” Emergency Hospital of Constanta with celiac disease after multiple admissions into the hospital for unspecific symptoms such as pallor, fatigue, pirosis, weight loss and 1-2 soft stools/day. The history with period irregularities and infertility without a known cause, a recent unexplained bone fracture, the muscle weakness, neuropsychiatric symptoms characterized by sleep disturbances and irritability correlated with the biological features characterized by moderate feriprive anemia, Ca and Mg decreased level, thyroid autoimmune impairment and gastrointestinal symptoms raised the suspicion of an autoimmune disorder with multiple targets. The videcapsule endoscopy (VCE) revealed the specific pattern of the celiac disease: villous atrophy of jejunum, scalloping, absent folds and cobblestone mucosal pattern. Results were correlated with immunology tests results. The patient was transferred on a gluten free diet and the clinical and VCE controlsrevealed the healing of the jejunum mucosa. The VCE can be the tool for positive diagnosis of an unusual and heterogeneous celiac disease in patients with various symptoms without an apparent cause.

A Descalloping Postprocessor for ScanSAR Images of Ocean Scenes

Due to its specific way of recording signals from multiple adjacent swaths in an alternating manner, a scanning synthetic aperture radar (SAR) (ScanSAR) cannot sample Doppler histories continuously like a SAR in stripmap mode. This can cause an effect known as azimuth scalloping, a wavelike modulation of the image intensity in near-azimuth direction. In theory, azimuth scalloping can be straightened out by using appropriate beam pattern corrections and multilooking techniques in the SAR processor. This works well over land, but lower signal-to-noise ratios and less accurate Doppler centroid estimates over water cause significant residual scalloping in many ScanSAR images of ocean scenes. The scalloping patterns hamper a correct interpretation of signatures of wind streaks, waves, and other phenomena. To overcome this problem once and for all, we have developed an algorithm that can eliminate scalloping patterns from existing ScanSAR images by postprocessing. Our algorithm detects the dominant scalloping pattern in an image automatically and eliminates most of it with very small side effects. We treat the scalloping pattern as a multiplicative effect, i.e., the amplitude spectrum of an affected image is assumed to be the convolution of the amplitude spectra of the unscalloped image and of the scalloping pattern. The proposed descalloping technique works partly in the spatial and partly in the spectral domain to approximate an exact deconvolution. We give a detailed technical description, show example results, and perform a quality analysis. We demonstrate the positive effects of the proposed descalloping treatment with a wind field retrieval example.

Peter B. Dews (1922–2012)

Peter B. Dews (1922–2012)

Flow accelerated corrosion of carbon steel feeder pipes from pressurized heavy water reactors

Detailed investigation of a number of feeder pipes received from Rajasthan Atomic Power Station Unit 2 (RAPS#2) after en-masse feeder pipe replacement after 15.67 Effective Full Power Years (EFPYs) was carried out. Investigations included ultrasonic thickness measurement by ultrasonic testing, optical microscopy, scanning electron microscopy, chemical analysis and X-ray Diffraction (XRD). Results showed that maximum thickness reduction of the feeder had occurred downstream and close to the weld in 32 NB (1.25″/32.75mm ID) elbows. Rate of Flow Accelerated Corrosion (FAC) was measured to be higher in the lower diameter feeder pipes due to high flow velocity and turbulence. Weld regions had thinned to a lower extent than the parent material due to higher chromium content in the weld. A weld protrusion has been shown to add to the thinning due to FAC and lead to faster thinning rate at localized regions. Surface morphology of inner surface of feeder had shown different size scallop pattern over the weld and parent material. Inter-granular cracks were also observed along the weld fusion line and in the parent material in 32 NB outlet feeder elbow.