Geometric Patterning Research Articles

Community as Gesamtkunstwerk: Dick Ket’s Self-Portraiture and the Debt of Epic Film

Abstract This essay posits that Weimar-era film sets—in their evocation of Richard Wagner’s concept of the Gesamtkunstwerk—served as a previously unseen visual source for painters that in some cases pushed back against interwar aesthetics of power. Focusing on the Dutch figurative painter Dick Ket, it investigates the ways in which this artist’s self-portraits from 1930–1940 acted as a memory index of his experience of the mises-en-scènes in Fritz Lang’s 1924 epic two-part film Die Nibelungs through Langian devices such as heavy geometric patterning, leitmotifs and subjugation of the human figure to the set. Ket’s work evinces the artist’s own sensation of confinement in his parents’ home as a result of a terminal heart condition while also reckoning with Adolf Hitler’s extremist rhetoric and expansionist policies in the years that preceded the German Occupation of the Netherlands.

Geometric control of myosin II orientation during axis elongation.

The actomyosin cytoskeleton is a crucial driver of morphogenesis. Yet how the behavior of large-scale cytoskeletal patterns in deforming tissues emerges from the interplay of geometry, genetics, and mechanics remains incompletely understood. Convergent extension in Drosophila melanogaster embryos provides the opportunity to establish a quantitative understanding of the dynamics of anisotropic non-muscle myosin II. Cell-scale analysis of protein localization in fixed embryos suggests that gene expression patterns govern myosin anisotropy via complex rules. However, technical limitations have impeded quantitative and dynamic studies of this process at the whole embryo level, leaving the role of geometry open. Here, we combine in toto live imaging with quantitative analysis of molecular dynamics to characterize the distribution of myosin anisotropy and the corresponding genetic patterning. We found pair rule gene expression continuously deformed, flowing with the tissue frame. In contrast, myosin anisotropy orientation remained approximately static and was only weakly deflected from the stationary dorsal-ventral axis of the embryo. We propose that myosin is recruited by a geometrically defined static source, potentially related to the embryo-scale epithelial tension, and account for transient deflections by cytoskeletal turnover and junction reorientation by flow. With only one parameter, this model quantitatively accounts for the time course of myosin anisotropy orientation in wild-type, twist, and even-skipped embryos, as well as embryos with perturbed egg geometry. Geometric patterning of the cytoskeleton suggests a simple physical strategy to ensure a robust flow and formation of shape.

Task Development to Measure Functional Thinking: Focusing on Third Graders’ Understanding

The purpose of this study was to develop the tasks to measure functional thinking and to verify their suitability by applying them to third-grade students. For this purpose, various tasks related to functional thinking were analyzed and developed according to the different modes of functional thinking and functional relationships. To verify the tasks, the Cronbach’s α value for each task type was calculated with the results of how the third graders solved the tasks. Exploratory factor analysis (EFA) was performed as needed. As a result, tasks were developed to measure four types of thinking: recursive, covariation, correspondence-particular, and correspondence-general. In particular, recursive patterning tasks were divided into repeated geometric patterns, growing geometric patterns, repeated numeric patterns, and growing numeric patterns through EFA. Only growing geometric patterning and growing numeric patterning tasks were found to be suitable for measuring third-grade students’ recursive thinking. Growing numeric patterning tasks were divided by arithmetic sequences and other sequences through EFA. The covariation, correspondence-particular, and correspondence-general tasks developed in this study were also verified. Contrary to the consistently high performance regarding the additive relationships, students’ functional thinking varied depending on the different types of functional relationships. This study is expected to inspire researchers to pay more attention to task development and verification to measure students’ functional thinking.

Three-dimensional nanoframes with dual rims as nanoprobes for biosensing

Three-dimensional (3D) nanoframe structures are very appealing because their inner voids and ridges interact efficiently with light and analytes, allowing for effective optical-based sensing. However, the realization of complex nanoframe architecture with high yield is challenging because the systematic design of such a complicated nanostructure lacks an appropriate synthesis protocol. Here, we show the synthesis method for complex 3D nanoframes wherein two-dimensional (2D) dual-rim nanostructures are engraved on each facet of octahedral nanoframes. The synthetic scheme proceeds through multiple executable on-demand steps. With Au octahedral nanoparticles as a sacrificial template, sequential processes of edge-selective Pt deposition and inner Au etching lead to Pt octahedral mono-rim nanoframes. Then, adlayers of Au are grown on Pt skeletons via the Frank-van der Merwe mode, forming sharp and well-developed edges. Next, Pt selective deposition on both the inner and outer boundaries leads to tunable geometric patterning on Au. Finally, after the selective etching of Au, Pt octahedral dual-rim nanoframes with highly homogeneous size and shape are achieved. In order to endow plasmonic features, Au is coated around Pt frames while retaining their geometric shape. The resultant plasmonic dual-rim engraved nanoframes possess strong light entrapping capability verified by single-particle surface-enhanced Raman scattering (SERS) and show the potential of nanoprobes for biosensing through SERS-based immunoassay.

A Subthreshold Layout Strategy for Faster and Lower Energy Complex Digital Circuits

This work presents complex circuitry from subthreshold standard cell libraries created by geometric STI spacer patterning for bulk planar CMOS technology nodes. Performance/leakage granularity enhancement affords safer multi-Vt synthesis in aggressive voltage scaling schemes. Libraries are evaluated in silicon through implementation of 32-bit datapath 128-bit AES cores. Intra-die nominal temperature (20 °C) analysis reveals improvements of up to 8.65×/24% MEP-to-MEP in frequency and energy-per-cycle respectively, compared to a state-of-the-art subthreshold library. A negative temperature correlation with performance enhancement is demonstrated extending beyond the cell level and into more complex designs. MEP-to-MEP performance enhancement and energy-per-cycle reduction are demonstrated over a temperature range of 0 °C to 85 °C.

When cells get in the flow.

New imaging approaches question a long-standing model for how the eyes of fruit flies acquire their geometric patterning.

Electronic Quantum Materials Simulated with Artificial Model Lattices.

The band structure and electronic properties of a material are defined by the sort of elements, the atomic registry in the crystal, the dimensions, the presence of spin–orbit coupling, and the electronic interactions. In natural crystals, the interplay of these factors is difficult to unravel, since it is usually not possible to vary one of these factors in an independent way, keeping the others constant. In other words, a complete understanding of complex electronic materials remains challenging to date. The geometry of two- and one-dimensional crystals can be mimicked in artificial lattices. Moreover, geometries that do not exist in nature can be created for the sake of further insight. Such engineered artificial lattices can be better controlled and fine-tuned than natural crystals. This makes it easier to vary the lattice geometry, dimensions, spin–orbit coupling, and interactions independently from each other. Thus, engineering and characterization of artificial lattices can provide unique insights. In this Review, we focus on artificial lattices that are built atom-by-atom on atomically flat metals, using atomic manipulation in a scanning tunneling microscope. Cryogenic scanning tunneling microscopy allows for consecutive creation, microscopic characterization, and band-structure analysis by tunneling spectroscopy, amounting in the analogue quantum simulation of a given lattice type. We first review the physical elements of this method. We then discuss the creation and characterization of artificial atoms and molecules. For the lattices, we review works on honeycomb and Lieb lattices and lattices that result in crystalline topological insulators, such as the Kekulé and “breathing” kagome lattice. Geometric but nonperiodic structures such as electronic quasi-crystals and fractals are discussed as well. Finally, we consider the option to transfer the knowledge gained back to real materials, engineered by geometric patterning of semiconductor quantum wells.

Encountering Proportional Reasoning During a Single Algebra Lesson: A Microgenetic Analysis

This case study explores how 12-13-year-old students encounter proportional reasoning while working with geometric patterning tasks using concrete materials. The focus is on the students’ use of spontaneous concepts when first dealing with such patterns in the context of collaborative work. Based on video recordings of a single lesson, a microgenetic analysis was performed to identify students’ learning trajectories, starting with students familiarizing themselves with pattern structure, followed by engagement in proportional reasoning, and ending with students perceiving a new technique to handle a situation where proportional reasoning did not suffice. While some student groups were able to move along the whole trajectory, most groups, when facing challenges, regressed to simpler techniques. The results provide new insights into students’ learning trajectories, which can be used to support students’ progress in the context of student-teacher interaction.

Patterning of Microorganisms and Microparticles through Sequential Capillarity-assisted Assembly.

Controlled patterning of microorganisms into defined spatial arrangements offers unique possibilities for a broad range of biological applications, including studies of microbial physiology and interactions. At the simplest level, accurate spatial patterning of microorganisms would enable reliable, long-term imaging of large numbers of individual cells and transform the ability to quantitatively study distance-dependent microbe-microbe interactions. More uniquely, coupling accurate spatial patterning and full control over environmental conditions, as offered by microfluidic technology, would provide a powerful and versatile platform for single-cell studies in microbial ecology. This paper presents a microfluidic platform to produce versatile and user-defined patterns of microorganisms within a microfluidic channel, allowing complete optical access for long-term, high-throughput monitoring. This new microfluidic technology is based on capillarity-assisted particle assembly and exploits the capillary forces arising from the controlled motion of an evaporating suspension inside a microfluidic channel to deposit individual microsized objects in an array of traps microfabricated onto a polydimethylsiloxane (PDMS) substrate. Sequential depositions generate the desired spatial layout of single or multiple types of micro-sized objects, dictated solely by the geometry of the traps and the filling sequence. The platform has been calibrated using colloidal particles of different dimensions and materials: it has proven to be a powerful tool to generate diverse colloidal patterns and perform surface functionalization of trapped particles. Furthermore, the platform was tested on microbial cells, using Escherichia coli cells as a model bacterium. Thousands of individual cells were patterned on the surface, and their growth was monitored over time. In this platform, the coupling of single-cell deposition and microfluidic technology allows both geometric patterning of microorganisms and precise control of environmental conditions. It thus opens a window into the physiology of single microbes and the ecology of microbe-microbe interactions, as shown by preliminary experiments.

Abstract MP59: Retinal Vascular Metrics Predict Pial Collateral Status in Patients With Acute Ischemic Stroke

Background: The extent of the pial collateral circulation may determine outcomes in an acute ischemic stroke. Experimental studies suggest that retinal vessel metrics and geometric patterning may predict the pial collateral status. We have undertaken a translational study to quantify and relate retinal vascular metrics to the grade of pial collaterals in patients with acute ischemic stroke. Method: 35 patients admitted with acute stroke underwent computed tomography angiography (OCT) and were graded as having good (n=20)(47.55 ± 10.65 years) or poor (n=15) (48.93 ± 10.91 years) pial collaterals and compared to healthy controls (n=21)(44.26 ± 10.15 years). Retinal images were generated using OCT and central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), artery-to-vein ratio (AVR), segmented fractal analysis and lacunarity, tortuosity index and fractal dimensions (capacity D 0 , information D 1 and correlation D 2 , curve asymmetry, singularity length and f-alfa-max using MONA software) were quantified. Results: Age ( p =0.709), BMI ( p =0.451), total cholesterol ( p =0.845), triglycerides ( p =0.679), LDL ( p =0.953), HDL ( p =0.361) and HbA 1c ( p =0.210) were comparable but the national institute of health stroke scale ( p =0.031) and modified Rankin Scale ( p =0.048) were higher in patients with poor compared to good collaterals. CRAE ( p =0.114), CRVE ( p =0.946), AVR ( p =0.114), lacunarity ( p =0.442), tortuosity index ( p =0.681), fractal analysis ( p =0.656), curve asymmetry ( p =0.619) and singularity length ( p =0.944) did not differ between patients with poor compared to good collaterals. However, fractal capacity D 0 (1.673 ± 0.029 vs 1.654 ± 0.025, p =0.042), fractal information D 1 (1.610 ± 0.027 vs 1.591 ± 0.024, p =0.036), fractal correlation D 2 (1.581± 0.028 vs 1.564 ± 0.024, p =0.060), and f alfa max (1.674 ± 0.027 vs 1.654 ± 0.025, p =0.030) were higher in patients with poor compared to good collaterals. Conclusion: This study shows differences in retinal vessel fractal dimensions between acute stroke patients with poor compared to good pial collaterals. This represents a non-invasive imaging method to define the pial collateral status and develop personalized intervention management strategies in acute ischemic stroke patients.

Competing Perceptual Salience in a Visual Word Recognition Task Differentially Affects Children With and Without Autism Spectrum Disorder.

Differences in visual attention have long been recognized as a central characteristic of autism spectrum disorder (ASD). Regardless of social content, children with ASD show a strong preference for perceptual salience-how interesting (i.e., striking) certain stimuli are, based on their visual properties (e.g., color, geometric patterning). However, we do not know the extent to which attentional allocation preferences for perceptual salience persist when they compete with top-down, linguistic information. This study examined the impact of competing perceptual salience on visual word recognition in 17 children with ASD (mean age 31 months) and 17 children with typical development (mean age 20 months) matched on receptive language skills. A word recognition task presented two images on a screen, one of which was named (e.g., Find the bowl!). On Neutral trials, both images had high salience (i.e., were colorful and had geometric patterning). On Competing trials, the distracter image had high salience but the target image had low salience, creating competition between bottom-up (i.e., salience-driven) and top-down (i.e., language-driven) processes. Though both groups of children showed word recognition in an absolute sense, competing perceptual salience significantly decreased attention to the target only in the children with ASD. These findings indicate that perceptual properties of objects can disrupt attention to relevant information in children with ASD, which has implications for supporting their language development. Findings also demonstrate that perceptual salience affects attentional allocation preferences in children with ASD, even in the absence of social stimuli. LAY SUMMARY: This study found that visually striking objects distract young children with autism spectrum disorder (ASD) from looking at relevant (but less striking) objects named by an adult. Language-matched, younger children with typical development were not significantly affected by this visual distraction. Though visual distraction could have cascading negative effects on language development in children with ASD, learning opportunities that build on children's focus of attention are likely to support positive outcomes.

Geometric Control of Collective Spontaneous Emission.

Dipole spin-wave states of atomic ensembles with wave vector k(ω) mismatched from the dispersion relation of light are difficult to access by far-field excitation but may support rich phenomena beyond the traditional phase-matched scenario in quantum optics. We propose and demonstrate an optical technique to efficiently access these states. In particular, subnanosecond laser pulses shaped by a home-developed wideband modulation method are applied to shift the spin wave in k space with state-dependent geometric phase patterning, in an error-resilient fashion and on timescales much faster than spontaneous emission. We verify this control through the redirection, switch off, and recall of collectively enhanced emission from a ^{87}Rb gas with ∼75% single-step efficiency. Our work represents a first step toward efficient control of electric dipole spin waves for studying many-body dissipative dynamics of excited gases, as well as for numerous quantum optical applications.

Made Visible: Contemporary South African Fashion and Identity curated by Kathryn Gunsch

Made Visible: Contemporary South African Fashion and Identity curated by Kathryn Gunsch

Improved control over polymer nanofiber deposition with a programmable 3-axis electrospinning apparatus

We built an electrospinning apparatus that integrates conventional electrospinning components with an FDM 3D-printing configuration, including real-time 3-axis control to improve accuracy and precision in nanofiber deposition over conventional far-field electrospinning. We motion-synced the spinneret needle and ground needle, incorporated a silver-coated stabilizer on the spinneret needle, and placed an aluminum-surfaced disc on the ground needle. Tests were executed to optimize accurate and precise, dry nanofiber collection at a typical flow rate and applied voltages. Our computer-controlled prototype maintained typical nanofiber characteristics obtained with far-field electrospinning while demonstrating it is capable of accurate stationary deposition and dynamic geometric patterning.

Unity and Multiplicity in Islamic Geometric and Calligraphic Expression: A Photographic and Visual Journey of Space in Nusantara Mosques

The paper describes how the experience and philosophy of Islamic unity and multiplicity are heightened through a photographic compilation of surface patterning; geometric and calligraphic in Mosques in the region. It then focuses on two mosques to highlight their particular contributions to achieved a contextualisation of such a universal aesthetic design and expression. Both masjid Negara Kuala Lumpur and the Istilal Mosque, Jakarta, represent key innovation, of prayer hall expression and decoration due to the contextualisation, and regionalization of essential geometric patterning, which departs from the usual stereotypical Islamic geometry to embrace and forward a Nusantara identity that resonates with minimalism and modernization in the industrialized world.

Smart material composites for discrete stiffness materials

This paper presents an initial step towards a new class of soft robotics materials, where localized, geometric patterning of smart materials can exhibit discrete levels of stiffness through combinations of smart materials. This work is inspired by a variety of biological systems where actuation is accomplished by modulating the local stiffness in conjunction with muscle contractions. Whereas most biological systems use hydrostatic mechanisms to achieve stiffness variability, and many robotic systems have mimicked this mechanism, this work aims to use smart materials to achieve this stiffness variability. Here the compositing of the low melting point Field’s metal, shape memory alloy Nitinol, and a low melting point thermoplastic Polycaprolactone (PCL), composited in simple beam structure encased in silicone rubber is presented. A simple two-joint soft robotic finger is constructed to demonstrate the dexterous capabilities of smart composite materials. The comparison in bending stiffnesses at different temperatures, which reside between the activation temperatures of the composited smart materials demonstrates the ability to achieve discrete levels of stiffnesses within the soft robotic tissue.

Engineering Biomimetic Materials for Skeletal Muscle Repair and Regeneration.

Although skeletal muscle is highly regenerative following injury or disease, endogenous self-regeneration is severely impaired in conditions of volume traumatic muscle loss. Consequently, tissue engineering approaches are a promising means to regenerate skeletal muscle. Biological scaffolds serve as not only structural support for the promotion of cellular ingrowth but also impart potent modulatory signaling cues that may be beneficial for tissue regeneration. In this work, the progress of tissue engineering approaches for skeletal muscle engineering and regeneration is overviewed, with a focus on the techniques to create biomimetic engineered tissue using extracellular cues. These factors include mechanical and electrical stimulation, geometric patterning, and delivery of growth factors or other bioactive molecules. The progress of evaluating the therapeutic efficacy of these approaches in preclinical models of muscle injury is further discussed.

The dynamics of rush circles in subalpine grassland

Geometric patterning in vegetation is often the result of cyclic succession, although circular forms sometimes result from the clonal growth of individual plants. We investigated whether cyclic succession or clonal growth created patterns in Poa subalpine grassland with rush (Empodisma minus) circles on the Central Plateau of Tasmania, Australia. We mapped change in the number, size and reflectance of the rush circles from 1953 to 2011 using aerial photographs, tested whether the circles occurred in distinct microenvironments, and whether the circles were likely to be individuals and determined whether the smallest circles were associated with disturbance. The number and area of circles increased with time. As circles became larger they became more reflective, evenly across their extent. The circles were associated with flatter patches in the plain. Surface soil characteristics did not differ between an exemplar circle and adjacent grassland. The Empodisma foliage in each circle tended to have colour consistently distinct from that of other circles in its vicinity, indicating that the circular form was a product of vegetative expansion of a single individual at a much more rapid velocity than the expansion of woody plant rings. The smaller circles were sometimes associated with frost-damaged Astelia alpina mounds, although far from confined to them. We did not find any instances of Empodisma circles <0.1 m in diameter. We deduced that the probability of establishment of new individuals of Empodisma in the grassland was extremely low, or depended on an infrequent disturbance. Although the increasing reflectance of circles with size and the lack of differentiation of soils between circle and grassland indicated the possibility of cyclic succession, the area covered by circles increased at the decadal time scale. The increases in circle coverage and number may have resulted from changes in climate and grazing regimes on the eastern Central Plateau since the 1940s.

Directional Stiffness Control Through Geometric Patterning and Localized Heating of Field’s Metal Lattice Embedded in Silicone

This research explores a new realm of soft robotic materials where the stiffness magnitude, directionality, and spatial resolution may be precisely controlled. These materials mimic biological systems where localized muscle contractions and adjustment of tissue stiffness enables meticulous, intelligent movement. Here we propose the use of a low-melting-point (LMP) metal lattice structure as a rigid frame using localized heating to allow compliance about selectable axes along the lattice. The resulting shape of the lattice is modeled using product of exponentials kinematics to describe the serial chain of tunably compliant axes; this model is found to match the behavior of the physical test piece consisting of a Field’s metal (FM) lattice encased in silicone rubber. This concept could enable highly maneuverable robotic structures with significantly improved dexterity.

Fabrication Approaches to Interconnect Based Devices for Stretchable Electronics: A Review.

Stretchable electronics promise to naturalize the way that we are surrounded by and interact with our devices. Sensors that can stretch and bend furthermore have become increasingly relevant as the technology behind them matures rapidly from lab-based workflows to industrially applicable production principles. Regardless of the specific materials used, creating stretchable conductors involves either the implementation of strain reliefs through insightful geometric patterning, the dispersion of stiff conductive filler in an elastomeric matrix, or the employment of intrinsically stretchable conductive materials. These basic principles however have spawned a myriad of materials systems wherein future application engineers need to find their way. This paper reports a literature study on the spectrum of different approaches towards stretchable electronics, discusses standardization of characteristic tests together with their reports and estimates matureness for industry. Patterned copper foils that are embedded in elastomeric sheets, which are closest to conventional electronic circuits processing, make up one end of the spectrum. Furthest from industry are the more recent circuits based on intrinsically stretchable liquid metals. These show extremely promising results, however, as a technology, liquid metal is not mature enough to be adapted. Printing makes up the transition between both ends, and is also well established on an industrial level, but traditionally not linked to creating electronics. Even though a certain level of maturity was found amongst the approaches that are reviewed herein, industrial adaptation for consumer electronics remains unpredictable without a designated break-through commercial application.