Ring-shaped Pattern Research Articles

Patterns of Fundus Autofluorescence Lifetimes In Eyes of Individuals With Nonexudative Age-Related Macular Degeneration.

PurposeTo investigate fundus autofluorescence (FAF) lifetimes in patients with nonexudative AMD.MethodsA total of 150 eyes of 110 patients (mean age: 73.2 ± 10.7 years) with nonexudative AMD, as well as a healthy group of 57 eyes in 38 subjects (mean age: 66.5 ± 8.7 years), were included. Investigations were conducted at the University Eye Clinic in Jena, Germany, as well as the Moran Eye Center in Salt Lake City, Utah, USA, using the Heidelberg Engineering Spectralis-based fluorescence lifetime imaging ophthalmoscope (FLIO). A 30° retinal field centered at the fovea was investigated. FAF decays were detected in short (498–560 nm) and long (560–720 nm, LSC) spectral channels. The mean fluorescence lifetimes (τm) were calculated. Optical coherence tomography scans and fundus photographs were also recorded.ResultsIn patients with nonexudative AMD, FLIO shows a ring-shaped pattern of prolonged τm in the LSC. This pattern occurs in all patients with AMD (including very early stages) and in one-third of the healthy controls. FAF lifetimes were longer with more advanced stages. The presence of drusen is associated with prolonged τm when compared with the healthy fundus, but drusen identification is difficult with FLIO only.ConclusionsFLIO detects a clear pattern of changes within the fundus, which appears to be AMD-associated. These changes are already visible in early AMD stages and not masked by the presence of other coexisting retinal diseases. These findings may be useful for the early diagnosis of AMD and to distinguish AMD from other retinal diseases.

Highly Interactive Brain\u2013Computer Interface Based on Flicker-Free Steady-State Motion Visual Evoked Potential

Visual evoked potential-based brain–computer interfaces (BCIs) have been widely investigated because of their easy system configuration and high information transfer rate (ITR). However, the uncomfortable flicker or brightness modulation of existing methods restricts the practical interactivity of BCI applications. In our study, a flicker-free steady-state motion visual evoked potential (FF-SSMVEP)-based BCI was proposed. Ring-shaped motion checkerboard patterns with oscillating expansion and contraction motions were presented by a high-refresh-rate display for visual stimuli, and the brightness of the stimuli was kept constant. Compared with SSVEPs, few harmonic responses were elicited by FF-SSMVEPs, and the frequency energy of SSMVEPs was concentrative. These FF-SSMVEPs evoked “single fundamental peak” responses after signal processing without harmonic and subharmonic peaks. More stimulation frequencies could thus be selected to elicit more responding fundamental peaks without overlap with harmonic peaks. A 40-target online SSMVEP-based BCI system was achieved that provided an ITR up to 1.52 bits per second (91.2 bits/min), and user training was not required to use this system. This study also demonstrated that the FF-SSMVEP-based BCI system has low contrast and low visual fatigue, offering a better alternative to conventional SSVEP-based BCIs.

Characterization of dough baked via blue laser

Depth of heat penetration and temperature must be precisely controlled to optimize nutritional value, appearance, and taste of food products. These objectives can be achieved with the use of a high-resolution blue diode laser—which operates at 445 nm—by adjusting the water content of the dough and the exposure pattern of the laser. Using our laser, we successfully cooked a 1 mm thick dough sample with a 5 mm diameter ring-shaped cooking pattern, 120 repetitions, 4000 mm min−1 speed, and 2 W laser power. Heat penetration in dough products with a blue laser is significantly higher compared to with an infrared laser. The use of a blue laser coupled with an infrared laser yields most optimal cooking conditions for food layered manufacture.

Fabrication of hexagonal star-shaped and ring-shaped patterns arrays by Mie resonance sphere-lens-lithography

Mie resonance sphere-lens-lithography has proved to be a good candidate for fabrication of large-area tunable surface nanopattern arrays. Different patterns on photoresist surface are obtained theoretically by adjusting optical coupling among neighboring spheres with different gap sizes. The effect of light reflection from the substrate on the pattern produced on the photoresist with a thin thickness is also discussed. Sub-micron hexagonal star-shaped and ring-shaped patterns arrays are achieved with close-packed spheres arrays and spheres arrays with big gaps, respectively. Changing of star-shaped vertices is induced by different polarization of illumination. Experimental results agree well with the simulation. By using smaller resonance spheres, sub-400 nm star-shaped and ring-shaped patterns can be realized. These tunable patterns are different from results of previous reports and have enriched pattern morphology fabricated by sphere-lens-lithography, which can find application in biosensor and optic devices.

Invasive Macrophytes Control the Spatial and Temporal Patterns of Temperature and Dissolved Oxygen in a Shallow Lake: A Proposed Feedback Mechanism of Macrophyte Loss.

Submerged macrophytes can have a profound effect on shallow lake ecosystems through their ability to modify the thermal structure and dissolved oxygen levels within the lake. Invasive macrophytes, in particular, can grow rapidly and induce thermal gradients in lakes that may substantially change the ecosystem structure and challenge the survival of aquatic organisms. We performed fine-scale measurements and 3D numerical modeling at high spatiotemporal resolution to assess the effect of the seasonal growth of Potamogeton crispus L. on the spatial and temporal dynamics of temperature and dissolved oxygen in a shallow urban lake (Lake Monger, Perth, WA, Australia). Daytime stratification developed during the growing season and was clearly observed throughout the macrophyte bed. At all times measured, stratification was stronger at the center of the macrophyte bed compared to the bed edges. By fitting a logistic growth curve to changes in plant height over time (r2 = 0.98), and comparing this curve to temperature data at the center of the macrophyte bed, we found that stratification began once the macrophytes occupied at least 50% of the water depth. This conclusion was strongly supported by a 3D hydrodynamic model fitted to weekly temperature profiles measured at four time periods throughout the growing season (r2 > 0.78 at all times). As the macrophyte height increased and stratification developed, dissolved oxygen concentration profiles changed from vertically homogeneous oxic conditions during both the day and night to expression of night-time anoxic conditions close to the sediments. Spatially interpolated maps of dissolved oxygen and 3D numerical modeling results indicated that the plants also reduced horizontal exchange with surrounding unvegetated areas, preventing flushing of low dissolved oxygen water out of the center of the bed. Simultaneously, aerial imagery showed central dieback occurring toward the end of the growing season. Thus, we hypothesized that stratification-induced anoxia can lead to accelerated P. crispus dieback in this region, causing formation of a ring-shaped pattern in spatial macrophyte distribution. Overall, our study demonstrates that submerged macrophytes can alter the thermal characteristics and oxygen levels within shallow lakes and thus create challenging conditions for maximizing their spatial coverage.

Tunable Negative Differential Resistance in MISIM Tunnel Diodes Structure With Concentric Circular Electrodes Controlled by Designed Substrate Bias

The tunable negative differential resistance (NDR) characteristics of metal–insulator–semiconductor–insulator–metal (MISIM) tunnel diodes (TDs) structure with thin oxide were observed by biasing the substrate simultaneously with one of the TDs under designed voltage drops ( $\Delta \text{V}$ ). An inner circular electrode TD surrounded by a ring-shape electrode TD gate pattern was adopted. The NDR region can be adjusted by varying the $\Delta \text{V}$ between the inner TD and the body. Not only the peak-to-valley current ratio (PVCR) but also the voltage range where NDR occurs can be controlled. It is supposed that the injected electrons and the inversion charges increase and decrease with negative bias, respectively, for the MIS(p) TD and play an important role in this observation. Meanwhile, the asymmetry of inner gate and ring gate enhances the coupling efficiency at reverse bias region. In this paper, the PVCR can be tuned to more than two orders and the voltage of the NDR region can be shifted to larger than 1 V. The tunable NDR characteristic of MISIM provides a possible application of MIS TD.

First Report of Corky Ringspot in Potatoes Caused by Tobacco rattle virus in Jiangsu Province, China

Tobacco rattle virus (TRV) belongs to the genus Tobravirus and is spread primarily by stubby-root nematodes, a group of microscopic, worm-like organisms in the genera Trichodorus and Paratrichodorus. These genera have been reported in Jiangsu Province of China previously (Liu and Cheng 1990). TRV causes the plant disease tobacco rattle in many plants (Hamed et al. 2012). Moreover, it causes the disease corky ringspot with the ring-shaped pattern of corky tissues symptoms in potato (Solanum tuberosum) tubers (David et al. 2010). This virus has been reported in Yangzhou City, Jiangsu Province, east China (He and Chen 2016). In June 2016, virus-like symptoms such as necrotic arcs and rings were observed in potato tubers from a single commercial field in Yangzhou City, Jiangsu Province, east China. Total RNA was extracted directly from the necrotic lesions of five tubers samples using Trizol reagent (Invitrogen, Carlsbad, CA), according to the manufacturer’s protocol. First-strand cDNA was prepared using M-ML...

Ring-shaped deposition patterns in small nozzle-to-plate distance impactors

ABSTRACTExperiments were carried out in an impactor, where the distance between the impactor nozzle and the impactor plate was small, much less than one nozzle diameter in separation. The aerosol deposition patterns in this impactor were investigated for aerosols in the 3–15 m diameter range. Ring-shaped deposition patterns were observed where the internal diameter and thickness of the rings were a function of the particle diameter. Specifically, the inner diameter and ring thickness were correlated to the Stokes number, Stk; the ring diameter decreased with Stk, and the ring thickness increased with Stk. At the ring closed up, leaving a mostly uniform disk deposition pattern. These ring patterns do not appear to correspond to patterns previously described in the literature, and an order of magnitude analysis shows that this is an inertially dominated process.Copyright © 2018 American Association for Aerosol Research

Fragment dispersal and plant-induced dieback explain irregular ring-shaped pattern formation in a clonal submerged macrophyte

Submerged macrophytes can colonize shallow lakes via several reproductive mechanisms, and can in turn substantially alter these environments by modifying the thermal structure and dissolved oxygen levels within these lakes. Although multiple mechanisms of submerged macrophyte expansion have been described, the relative contribution of each of these in shallow lake environments has been largely overlooked. In this study we analyzed the spatial spread and patterning during seasonal growth of a globally invasive submerged macrophyte, Potamogeton crispus, in a shallow urban lake (Lake Monger, Western Australia). We used underwater and aerial imagery to estimate the spatial pattern of the P. crispus bed. By comparing the spatial extent of the bed at different times during the growing season, we found linear expansion rates two orders of magnitude higher than those previously estimated through rhizome elongation. We formulated a deterministic mathematical model that accounted for the ability of P. crispus to spread through rhizomes and fragments broken off by the feeding activities of aquatic birds, to assess the contribution of fragment dispersal to the emergent patterns of the submerged macrophyte bed. In addition to accounting for dispersal from fragments, the model also accounted for a hypothesized feedback between macrophyte-induced thermal stratification and central dieback. Comparison of our model results against field data indicated that the model accurately represented the spatial spread of the macrophyte bed when fragment dispersal was included. When fragment dispersal was not included in the model, the spatial spread of the bed was largely underestimated, suggesting that fragment dispersal may well account for the fast seasonal spread of this species. The model also captured the formation of a ring-shaped pattern in spatial macrophyte distribution suggesting that both fragment dispersal and the feedback between stratification and dieback are necessary to reproduce the spatial structure of the macrophyte bed. Our results highlight the potential important role of fragment dispersal in facilitating colonization and submerged macrophyte invasion in shallow lakes.

An integrated method for cell isolation and migration on a chip

Tumour cell migration has an important impact on tumour metastasis. Magnetic manipulation is an ascendant method for guiding and patterning cells. Here, a unique miniaturized microfluidic chip integrating cell isolation and migration assay was designed to isolate and investigate cell migration. The chip was fabricated and composed of a magnet adapter, a polytetrafluoroethylene(PDMS) microfluidic chip and six magnetic rings. This device was used to isolate MCF-7 cells from MDA-MB-231-RFP cells and evaluate the effects of TGF-β on MCF-7 cells. First, the two cell types were mixed and incubated with magnetic beads modified with an anti-EpCAM antibody. Then, they were slowly introduced into the chip. MCF-7 cells bond to the magnetic beads in a ring-shaped pattern, while MDA-MB-231-RFP cells were washed away by PBS. Cell viability was examined during culturing in the micro-channel. The effects of TGF-β on MCF-7 cells were evaluated by migration distance and protein expression. The integrated method presented here is novel, low-cost and easy for performing cell isolation and migration assay. The method could be beneficial for developing microfluidic device applications for cancer metastasis research and could provide a new method for biological experimentation.

Multibeam interferometric optical tweezers

Using the interference of N collimated laser beams, optical lattices with N-fold rotational symmetry are generated over the interface of two semi-infinite dielectric media. The interaction of small dielectric particles with these interference patterns is investigated using Rayleigh approximation. The polarization state of the interfering beams considerably influences the interference patterns and potential landscapes. Therefore, both parallel and perpendicular polarized interfering beams are considered and the corresponding potential profiles are compared and analyzed. We also study how the number of interfering waves, incident and azimuth angles, and initial phases of the incident beams influence optical lattices and potential profiles. It is found that the ring-shaped patterns with good confinement properties can be achieved by increasing the number of incident beams. In addition, by increasing the number of incident beams one can make an optical trap with sharper intensity gradient and deeper potential well, which is an advantage for trapping small Rayleigh particles. The lattices resulting from the interference of N incident waves with different incident angles are also investigated. Furthermore, the effects of changing the azimuth angles between two adjacent incident wave vectors on the intensity patterns are studied. The proposed configuration and the numerical results can find numerous applications in particle arrangement, particle sorting, and the creation of quasicrystals. We believe that interference approaches have many potential capabilities for molding light wavefronts and creating multiple traps with sophisticated patterns.

Galactic rings revisited – I. CVRHS classifications of 3962 ringed galaxies from the Galaxy Zoo 2 Database

Rings are important and characteristic features of disc-shaped galaxies. This paper is the first in a series that re-visits galactic rings with the goals of further understanding the nature of the features and for examining their role in the secular evolution of galaxy structure. The series begins with a new sample of 3962 galaxies drawn from the Galaxy Zoo 2 citizen science data base, selected because zoo volunteers recognized a ring-shaped pattern in the morphology as seen in Sloan Digital Sky Survey colour images. The galaxies are classified within the framework of the Comprehensive de Vaucouleurs revised Hubble-Sandage system. It is found that zoo volunteers cued on the same kinds of ring-like features that were recognized in the 1995 Catalogue of Southern Ringed Galaxies. This paper presents the full catalogue of morphological classifications, comparisons with other sources of classifications and some histograms designed mainly to highlight the content of the catalogue. The advantages of the sample are its large size and the generally good quality of the images; the main disadvantage is the low physical resolution that limits the detectability of linearly small rings such as nuclear rings. The catalogue includes mainly inner and outer disc rings and lenses. Cataclysmic (‘encounter-driven’) rings (such as ring and polar ring galaxies) are recognized in less than 1 per cent of the sample.

Acoustical breakdown of materials by focusing of laser-generated Rayleigh surface waves

Focusing of high-amplitude surface acoustic waves leading to material damage is visualized in an all-optical experiment. The optical setup includes a lens and an axicon that focuses an intense picosecond excitation pulse into a ring-shaped pattern at the surface of a gold-coated glass substrate. Optical excitation induces a surface acoustic wave (SAW) that propagates in the plane of the sample and converges toward the center. The evolution of the SAW profile is monitored using interferometry with a femtosecond probe pulse at variable time delays. The quantitative analysis of the full-field images provides direct information about the surface displacement profiles, which are compared to calculations. The high stress at the focal point leads to the removal of the gold coating and, at higher excitation energies, to damage of the glass substrate. The results open the prospect for testing material strength on the microscale using laser-generated SAWs.

Flexible Controls of Terahertz Waves Using Coding and Programmable Metasurfaces

In the first part of the paper, we make a brief review on the coding and programmable metasurfaces recently proposed at microwave and terahertz frequencies, which are realized by distributing coding particles “0” and “1” with opposite reflection phases on surfaces with certain coding sequences. The powerful manipulations to microwaves and terahertz waves using the coding and programmable metasurfaces are presented. In the second part of the paper, we propose a new coding scheme for the generation of ring-shaped radiation pattern. Different coding strategies are provided to demonstrate the flexible controls of the size, position, and number of rings in the radiation patterns, including changing the periodicity of the gradient coding sequence and adding it with one or multiple periodic sequences. A new structure featuring low electromagnetic interference and ultrahigh efficiency is designed to implement the ring-shaped pattern, which shows highly consistent results to the theoretical results calculated by Fourier transform. We remark that such a ring-shaped radiation pattern may find a wide range of applications in radar detections.

The evolutionary process of the geomorphology of tidal embayments in southern Jiaodong Peninsula, China

Based on the theory of flood/ebb asymmetry, the evolution of the geomorphology of representative bays along the southern coast of the Jiaodong Peninsula over the last 40 years was investigated using remote sensing and geographic information system technologies. The results showed that coastal features such as tidal flats and tidal inlets in the bays changed significantly over time. The studied bays are in a ring-shaped geomorphic spatial pattern characterized by shallow water, and they were concentrically ringed by tidal flats and coastal plains before the early 1980s. Later, however, a number of ponds appeared between the coastal plains and tidal flats. The extent of sediment infill for each bay in the 1980s was greater than that in the 1970s. The conversion of flat-inlets and the erosion/deposition change of tidal inlets in these four bays during study period were not synchronized. Each bay was in a state of flood asymmetry, and both the net fine and net coarse sediment deposition took place in the 1970s. From the late 1960s to the early 1980s, Dingzi Bay was characterized by flood asymmetry, and its tidal asymmetry ratio increased. The Jinghai and the Wuleidao bays were in a state of flood asymmetry, and their tidal asymmetry ratios decreased, while Rushan Bay was in a transition state from flood to ebb asymmetry. However, intensive human activities over the last 30 years, especially the construction of coastal ponds, has greatly changed the hydrology and sedimentation of these bays, causing profound changes in geomorphic features; furthermore, these changes have guided the evolutionary process of the bays. Our results suggest that the intensive human activities were key factors that caused changes in the geomorphic evolution of the studied tidal embayments, especially the sudden change from a state of rising flood asymmetry to ebb asymmetry in Dingzi Bay.

Reciprocal space engineering with hyperuniform gold disordered surfaces

Hyperuniform geometries feature correlated disordered topologies which follow from a tailored k-space design. Here, we study gold plasmonic hyperuniform disordered surfaces and, by momentum spectroscopy, we report evidence of k-space engineering on both light scattering and light emission. Even if the structures lack a well-defined periodicity, emission and scattering are directional in ring-shaped patterns. The opening of these rotational-symmetric patterns scales with the hyperuniform correlation length parameter as predicted via the spectral function method.

Sensitive Gap-Enhanced Raman Spectroscopy with a Perfect Radially Polarized Beam

Gap mode surface-enhanced Raman spectroscopy (SERS) enables high enhancement of Raman signal. However, the polarization of excitation light shows great influence on the excitation of gap mode and hence on the Raman enhancement. Here, we propose a nanoparticle-on-film gap mode SERS accompanying with a new type of excitation source called as perfect radially polarized (PRP) beam. The PRP beam possesses a ring-shaped beam pattern that can be tuned to match the surface plasmon resonance angle under a tight focusing condition, hence improving greatly the excitation efficiency of surface plasmon polaritons, and eventually the sensitivity of gap mode SERS. Such kind of enhanced-Raman system with a PRP beam has a great potential on the applications such as single molecule Raman detection.

GPU-based low-level trigger system for the standalone reconstruction of the ring-shaped hit patterns in the RICH Cherenkov detector of NA62 experiment

This project aims to exploit the parallel computing power of a commercial Graphics Processing Unit (GPU) to implement fast pattern matching in the Ring Imaging Cherenkov (RICH) detector for the level 0 (L0) trigger of the NA62 experiment. In this approach, the ring-fitting algorithm is seedless, being fed with raw RICH data, with no previous information on the ring position from other detectors. Moreover, since the L0 trigger is provided with a more elaborated information than a simple multiplicity number, it results in a higher selection power. Two methods have been studied in order to reduce the data transfer latency from the readout boards of the detector to the GPU, i.e., the use of a dedicated NIC device driver with very low latency and a direct data transfer protocol from a custom FPGA-based NIC to the GPU. The performance of the system, developed through the FPGA approach, for multi-ring Cherenkov online reconstruction obtained during the NA62 physics runs is presented.

Real-time track-less Cherenkov ring fitting trigger system based on Graphics Processing Units

The parallel computing power of commercial Graphics Processing Units (GPUs) is exploited to perform real-time ring fitting at the lowest trigger level using information coming from the Ring Imaging Cherenkov (RICH) detector of the NA62 experiment at CERN. To this purpose, direct GPU communication with a custom FPGA-based board has been used to reduce the data transmission latency. The GPU-based trigger system is currently integrated in the experimental setup of the RICH detector of the NA62 experiment, in order to reconstruct ring-shaped hit patterns. The ring-fitting algorithm running on GPU is fed with raw RICH data only, with no information coming from other detectors, and is able to provide more complex trigger primitives with respect to the simple photodetector hit multiplicity, resulting in a higher selection efficiency. The performance of the system for multi-ring Cherenkov online reconstruction obtained during the NA62 physics run is presented.

Rainbow Stars—Multi-Color Laser Emission for Science and Art

Rainbow Stars—Multi-Color Laser Emission for Science and Art