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Journal articles on the topic 'Shadow ring'

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Published: 4 June 2021
Last updated: 2 February 2022

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1

Muro-Arena, G. A., M. Benisty, C. Ginski, C. Dominik, S. Facchini, M. Villenave, R. van Boekel, et al. "Shadowing and multiple rings in the protoplanetary disk of HD 139614." Astronomy & Astrophysics 635 (March 2020): A121. http://dx.doi.org/10.1051/0004-6361/201936509.

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Context. Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or misalignments between disk regions. These warps are possibly caused by an inclined (sub-)stellar companion embedded in the disk. Aims. We aim to study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on the first scattered light observations of this disk, which we model with the radiative transfer code MCMax3D. Methods. We obtained J- and H-band observations that show strong azimuthal asymmetries in polarized scattered light with VLT/SPHERE. In the outer disk, beyond ~30 au, a broad shadow spans a range of ~240 deg in position angle, in the east. A bright ring at ~16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental with the brightest region of the outer disk. Additionally, two arcs are detected at ~34 and ~50 au. We created a simple four-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features. The location and misalignment of the disk components were constrained from the shape and location of the shadows they cast. Results. We find that the shadow on the outer disk covers a range of position angles too wide to be explained by a single inner misaligned component. Our model requires a minimum of two separate misaligned zones – or a continuously warped region – to cast this broad shadow on the outer disk. A small misalignment of ~4° between adjacent components can reproduce most of the observed shadow features. Conclusions. Multiple misaligned disk zones, potentially mimicking a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in the disk, located on an inclined orbit, could be responsible for such a feature and for the dust-depleted gap responsible for a dip in the SED.
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2

Sánchez, G., A. Serrano, M. L. Cancillo, and J. A. García. "Comparison of shadow-ring correction models for diffuse solar irradiance." Journal of Geophysical Research: Atmospheres 117, no. D9 (May 9, 2012): n/a. http://dx.doi.org/10.1029/2011jd017346.

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3

Petit, Charles. "Silhouette: Scientists attempt to image a shadow and its tumultuous ring." Science News 178, no. 8 (September 29, 2010): 22–26. http://dx.doi.org/10.1002/scin.5591780822.

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4

Vartiainen, Eero. "An anisotropic shadow ring correction method for the horizontal diffuse irradiance measurements." Renewable Energy 17, no. 3 (July 1999): 311–17. http://dx.doi.org/10.1016/s0960-1481(98)00756-3.

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5

Aguirre-Pablo, Andres A., Kenneth R. Langley, and Sigurdur T. Thoroddsen. "High-Speed Time-Resolved Tomographic Particle Shadow Velocimetry Using Smartphones." Applied Sciences 10, no. 20 (October 13, 2020): 7094. http://dx.doi.org/10.3390/app10207094.

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The video-capabilities of smartphones are rapidly improving both in pixel resolution and frame-rates. Herein we use four smartphones in the “slow-mo” option to perform time-resolved Tomographic Particle Shadow Velocimetry of a vortex ring, using 960 fps. We use background LED-illuminated diffusers, facing each camera, for shadow particle imaging. We discuss in-depth the challenges present in synchronizing the high-speed video capture on the smartphones and steps to overcome these challenges. The resulting 3-D velocity field is compared to an instantaneous, concurrent, high-resolution snapshot with four 4k-video cameras using dual-color to encode two time-steps on a single frame. This proof-of-concept demonstration, supports realistic low-cost alternatives to conventional 3-D experimental systems.
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6

Huang, Yang, Yi-Ping Dong, and Dao-Jun Liu. "Revisiting the shadow of a black hole in the presence of a plasma." International Journal of Modern Physics D 27, no. 12 (September 2018): 1850114. http://dx.doi.org/10.1142/s0218271818501146.

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We study the photon’s motion around a black hole in the presence of a plasma whose density is a function of the radius coordinate by a renewed ray-tracing algorithm and investigate the influence of the plasma on the shadow of the black hole. The presence of plasma affects not only the size but also the shape of the black hole shadow. Furthermore, the influence of plasma on trajectories of photons depends on the frequency of the photons. For the high-frequency photons, the influence is negligible, on the contrary, the trajectories of low-frequency photons are affected significantly by the plasma. Interestingly, it is also found that the black hole image would take on a multi-ring structure due to the presence of plasma.
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7

de Oliveira, Amauri P., Antonio J. Machado, and João F. Escobedo. "A New Shadow-Ring Device for Measuring Diffuse Solar Radiation at the Surface." Journal of Atmospheric and Oceanic Technology 19, no. 5 (May 2002): 698–708. http://dx.doi.org/10.1175/1520-0426(2002)019<0698:ansrdf>2.0.co;2.

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8

Johnson, Michael D., Alexandru Lupsasca, Andrew Strominger, George N. Wong, Shahar Hadar, Daniel Kapec, Ramesh Narayan, et al. "Universal interferometric signatures of a black hole’s photon ring." Science Advances 6, no. 12 (March 2020): eaaz1310. http://dx.doi.org/10.1126/sciadv.aaz1310.

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The Event Horizon Telescope image of the supermassive black hole in the galaxy M87 is dominated by a bright, unresolved ring. General relativity predicts that embedded within this image lies a thin “photon ring,” which is composed of an infinite sequence of self-similar subrings that are indexed by the number of photon orbits around the black hole. The subrings approach the edge of the black hole “shadow,” becoming exponentially narrower but weaker with increasing orbit number, with seemingly negligible contributions from high-order subrings. Here, we show that these subrings produce strong and universal signatures on long interferometric baselines. These signatures offer the possibility of precise measurements of black hole mass and spin, as well as tests of general relativity, using only a sparse interferometric array.
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9

Beauchez, Jérôme. "In the Shadow of the Other: Boxing, Everyday Struggles and the Feeling of Strangeness." Sociology 50, no. 6 (July 11, 2016): 1170–84. http://dx.doi.org/10.1177/0038038515587638.

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On the basis of an ethnography of a group of boxers, this article questions pugilism as an experience of confrontation with the other, the reasons and effects of which lie beyond the ring. Using the boxers’ words to explain their everyday struggles, this article seeks to describe fighting figures by placing them in the full depth of their biographical paths. These boxers share the experience of immigration and their life stories have all been marked by profound feelings of strangeness, understood as a social disqualification of otherness that causes deep and private wounds. Like the shadow of the other, hanging over the ‘conversations of gestures’, the boxers’ wounds and the violence of their biographical paths can help explain how they experience their fights, through the idea of a bodily response to all the hardships they have endured, well beyond the ring and its rounds.
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Barkhudarov, E. M., M. O. Mdivnishvili, I. V. Sokolov, M. I. Taktakishvili, and V. E. Terekhin. "Mach reflection of a ring shock wave from the axis of symmetry." Journal of Fluid Mechanics 226 (May 1991): 497–509. http://dx.doi.org/10.1017/s0022112091002483.

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The paper is devoted to the theoretical and experimental investigation of the ring (toroidal) shock wave near the axis of symmetry. The theoretical approach is based upon the Chester–Chisnell–Whitman method. The experimental toroidal shock wave is generated by a novel inducer and visualized by the shadow technique. Attention is paid to the manner of reflection of the shock wave from the axis of symmetry. This reflection appears to be irregular even at small distances from the centre of the ring. This phenomenon is due to the cumulative acceleration of the converging axisymmetric shock front near the axis. The acceleration results in an increase in the incidence angle up to that characteristic of Mach (irregular) reflection.
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11

Gwinner, Michael Christian, Elisabeth Koroknay, Liwei Fu, Piotr Patoka, Witold Kandulski, Michael Giersig, and Harald Giessen. "Periodic Large-Area Metallic Split-Ring Resonator Metamaterial Fabrication Based on Shadow Nanosphere Lithography." Small 5, no. 3 (February 6, 2009): 400–406. http://dx.doi.org/10.1002/smll.200800923.

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12

Constandinou, Timothy G., and Julius Georgiou. "Micro-Optoelectromechanical Tilt Sensor." Journal of Sensors 2008 (2008): 1–7. http://dx.doi.org/10.1155/2008/782764.

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This paper presents a novel hybrid CMOS/MEMS tilt sensor with a5∘resolution over a300∘range. The device uses a MEMS-based semicircular mass suspended from a rigid body, projecting a shadow onto the CMOS-based optical sensor surface. A one-dimensional photodiode array arranged as a uniformly segmented ring is then used to determine the tilt angle by detecting the position of the semicircular mass. The complete sensor occupies an area of under 2.5 mm×2.5 mm.
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13

Hay, Ronald T. "Decoding the SUMO signal." Biochemical Society Transactions 41, no. 2 (March 21, 2013): 463–73. http://dx.doi.org/10.1042/bst20130015.

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SUMO (small ubiquitin-like modifier) emerged from the shadow of the well-established ubiquitin some 15 years ago when it was shown that a distinct conjugation pathway was responsible for SUMO modification. Since then it has been established that SUMO modifies over a thousand substrates and plays diverse roles in many important biological processes. Recognition of SUMO is mediated by short peptide sequences known as SIMs (SUMO-interaction motifs) that allow effector proteins to engage SUMO-modified substrates. Like ubiquitin, SUMO can form polymeric chains, and these chains can be recognized by proteins containing multiple SIMs. One protein that contains such a sequence of SIMs also contains a RING (really interesting new gene) domain that is the hallmark of a ubiquitin E3 ligase. This ubiquitin ligase known as RNF4 (RING finger protein 4) has the unique property that it can recognize SUMO-modified proteins and target them for ubiquitin-mediated proteolysis. Structural and biochemical analyses of RNF4 has shed light on the long sought after mechanism of ubiquitin transfer and illustrates how its RING domain primes the ubiquitin-loaded E2 for catalysis.
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14

Ridene, Safa, Reda Yaagoubi, Imane Sebari, and Audrey Alajouanine. "Shadow detection and correction using a combined 3D GIS and image processing approach." Revue Internationale de Géomatique 29, no. 3-4 (July 2019): 241–53. http://dx.doi.org/10.3166/rig.2019.00091.

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While shadow can give useful information about size and shape of objects, it can pose problems in feature detection and object detection, thereby, it represents one of the major perturbator phenomenons frequently occurring on images and unfortunately, it is inevitable. “Shadows may lead to the failure of image analysis processes and also cause a poor quality of information which in turn leads to problems in implementation of algorithms.” (Mahajan and Bajpayee, 2015). It also affects multiple image analysis applications, whereby shadow cast by buildings deteriorate the spectral values of the surfaces. Therefore, its presence causes a deterioration in the visual image's quality and limits the information that the former could give. Ignoring the existence of shadows in images may cause serious problems in various visual processing applications such as false objects detection. In this context, many researches have been conducted through years. However, it is still a challenge for analysts all over the world to find a fully automated and efficient method for shadow removal from images.
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Dal Pai, Alexandre, Enzo Dal Pai, Valéria Cristina Rodrigues Sarnighausen, and João Francisco Escobedo. "Evaluation of anisotropic correction models for diffuse solar irradiance measured by the MEO shadow ring method." Journal of Renewable and Sustainable Energy 12, no. 6 (November 2020): 063701. http://dx.doi.org/10.1063/5.0012181.

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16

Wagner, T., S. Beirle, and T. Deutschmann. "Three-dimensional simulation of the Ring effect in observations of scattered sun light using Monte Carlo radiative transfer models." Atmospheric Measurement Techniques 2, no. 1 (April 22, 2009): 113–24. http://dx.doi.org/10.5194/amt-2-113-2009.

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Abstract. We present a new technique for the quantitative simulation of the "Ring effect" for scattered light observations from various platforms and under different atmospheric situations. The method is based on radiative transfer calculations at only one wavelength λ0 in the wavelength range under consideration, and is thus computationally fast. The strength of the Ring effect is calculated from statistical properties of the photon paths for a given situation, which makes Monte Carlo radiative transfer models in particular appropriate. We quantify the Ring effect by the so called rotational Raman scattering probability, the probability that an observed photon has undergone a rotational Raman scattering event. The Raman scattering probability is independent from the spectral resolution of the instrument and can easily be converted into various definitions used to characterise the strength of the Ring effect. We compare the results of our method to the results of previous studies and in general good quantitative agreement is found. In addition to the simulation of the Ring effect, we developed a detailed retrieval strategy for the analysis of the Ring effect based on DOAS retrievals, which allows the precise determination of the strength of the Ring effect for a specific wavelength while using the spectral information within a larger spectral interval around the selected wavelength. Using our technique, we simulated synthetic satellite observation of an atmospheric scenario with a finite cloud illuminated from different sun positions. The strength of the Ring effect depends systematically on the measurement geometry, and is strongest if the satellite points to the side of the cloud which lies in the shadow of the sun.
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17

Алмазова, К. И., А. Н. Белоногов, В. В. Боровков, Е. В. Горелов, И. В. Морозов, А. А. Тренькин, and С. Ю. Харитонов. "Исследование динамики искрового разряда в воздухе в промежутке острие--плоскость методом теневого фотографирования." Журнал технической физики 89, no. 1 (2019): 69. http://dx.doi.org/10.21883/jtf.2019.01.46964.178-18.

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AbstractThe microchannel structure of a spark discharge in a 1.5-mm-long point–plane gap has been studied by the method of shadow photography. The discharge dynamics (propagation of microchannels from the point into the discharge gap, branching and expansion of the microchannels, formation of a joint front of the spark’s shock wave and its motion) has been observed over a time from several nanoseconds to several hundred nanoseconds. Objects of a half-ring shape have been discovered. They have been identified as semispherical shock waves resulting from the formation of microcraters near sites where the microchannels touch the plane electrode.
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18

Wandreal, Johansson. "Is Black Hole A Hole?" Science Insights 28, no. 3 (April 15, 2019): 29–32. http://dx.doi.org/10.15354/si.19.vw011.

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The first picture of block hole was released on April 10th, 2019. This breakthrough came after a decade of collaborate work to align the myriad parts of the giant project and gain the highest resolution possible from the Earth’s surface. Even from our original consideration, block hole is a mysterious greedy hole that can suck anything away no matter how big the matter is. However, the newly released results indicated that block hole is not the imaginary hole; it is as a dark shadow within a doughnut-like ring of hot, glowing material with almost the size of our solar system.
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19

Harper-Scott, J. P. E. "Medieval Romance and Wagner's Musical Narrative in the Ring." 19th-Century Music 32, no. 3 (2009): 211–34. http://dx.doi.org/10.1525/ncm.2009.32.3.211.

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Abstract Wagner's engagement with medieval sources like the Nibelungenlied has generally been examined in relation to poetic style in his librettos. One of the defining structural features of his literary inspirations is the narrative interlace structure, which is common to literature, art, and even manuscript organization in the Middle Ages. In place of the classical Aristotelian unity of time, place, and action, the interlace design sets up a literary form based on sudden disjunctions, mysterious failures of explanation, and multiplicities of motive. These formal models propose radically different views of reality and the self: one suggests that human experience is shaped by a culmination that can already be known, the other more contingent, fractured, and paradoxically ““modern.”” Wagner's incorporation of the interlace design operates in the libretto and, more significantly and complexly, in the music. Wagner's structural and philosophical engagement with his medieval sources in the Ring may be elucidated via a combination of neo-Riemannian and modified Schenkerian analytical approaches and a sensitivity to Wagner's tendency to highlight the structural joints between his massive interlaced threads (rather than smoothly modulating, as the prevalent view suggests). The work is seen to have an existentialist, not an essentialist, view of human nature that provided an intellectual model for the artists and thinkers that grew up in Wagner's considerable intellectual shadow.
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BATISHCHEVA, Ksenia A., Yuliya N. Vympina, and Evgeniya G. ORLOVA. "The influence of laser treatment of aluminum-magnesium alloy surface on the ”self-assembly” of nanoparticles during the evaporation of colloidal solution." Tyumen State University Herald. Physical and Mathematical Modeling. Oil, Gas, Energy 7, no. 1 (2021): 26–43. http://dx.doi.org/10.21684/2411-7978-2021-7-1-26-43.

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Establishing the characteristics of the self-assembly of micron and sub-micron particles when colloidal solution droplets evaporate from solid surfaces is an urgent problem. This is explained by the possibility of using these structures obtained by droplet technologies to create and optimize the production of direct and indirect liquid cooling devices, electronic and sensor working boards, current-conducting coatings, optical crystals, and chemo sensors. The method used in this study for processing of metals and alloys by laser radiation is prospective for controlling the processes at the liquid/gas/solid interface. This article aims to analyze the effect of laser processing of the widely used in the industry aluminum-magnesium alloy on the formation of a layer of particles during the droplet evaporation of colloidal solutions. The samples’ surfaces were processed by two methods: polished by tumbling and nanosecond laser pulses. The geometric parameters of the droplets of colloidal solutions evaporating from the samples’ surfaces were determined by the shadow method. To process the obtained shadow images, the Young — Laplace method was used. Using a scanning electron microscope, the authors have received the images of the particles’ layers formed due to the droplet evaporation of colloidal solutions. The experimental studies reveal the effect of texture formed on aluminum-magnesium alloy sample on the morphology of the layer of polystyrene nanoparticles during the droplet evaporation of colloidal solutions. Due to the self-assembly of particles, solid ring-like sediments are formed, which are elongated under the action of the capillary force parallel to the motion vector of the laser beam (when creating the texture). When the solvent evaporated from the solution droplet on the textured surface, in addition to the rings, a homogeneous layer of polystyrene particles was formed. This refers to the droplet evaporation of the solution. The results show that with an increase in the concentration of particles in the solution, the sizes of radial cracks on the rings formed due to particle deposition increase. There were no cracks on the rings at a relatively low volume concentration of particles.
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21

Chaiyapinunt, Somsak, Pawin Ruttanasupa, Vutipon Ariyapoonpong, and Kanpot Duanmeesook. "A shadow-ring device for measuring diffuse solar radiation on a vertical surface in a tropical zone." Solar Energy 136 (October 2016): 629–38. http://dx.doi.org/10.1016/j.solener.2016.07.044.

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22

Malet-Damour, Bruno, Stéphane Guichard, Aurélien P. Jean, Frédéric Miranville, and Harry Boyer. "SHADECO: A low-cost shadow-ring for diffuse measures: State of the art, principles, design and application." Renewable Energy 117 (March 2018): 71–84. http://dx.doi.org/10.1016/j.renene.2017.09.083.

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23

Kudish, A. I., and A. Ianetz. "Analysis of diffuse radiation data for Beer Sheva: Measured (shadow ring) versus calculated (global-horizontal beam) values." Solar Energy 51, no. 6 (December 1993): 495–503. http://dx.doi.org/10.1016/0038-092x(93)90134-a.

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24

Guerrero, M. A., G. Ramos-Larios, J. A. Toalá, B. Balick, and L. Sabin. "Rings and arcs around evolved stars – II. The Carbon Star AFGL 3068 and the Planetary Nebulae NGC 6543, NGC 7009, and NGC 7027." Monthly Notices of the Royal Astronomical Society 495, no. 2 (May 16, 2020): 2234–46. http://dx.doi.org/10.1093/mnras/staa1225.

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ABSTRACT We present a detailed comparative study of the arcs and fragmented ring-like features in the haloes of the planetary nebulae (PNe) NGC 6543, NGC 7009, and NGC 7027 and the spiral pattern around the carbon star AFGL 3068 using high-quality multi-epoch HST images. This comparison allows us to investigate the connection and possible evolution between the regular patterns surrounding AGB stars and the irregular concentric patterns around PNe. The radial proper motion of these features, ≃15 km s−1, are found to be consistent with the AGB wind and their linear sizes and interlapse times (500–1900 yr) also agree with those found around AGB stars, suggesting a common origin. We find evidence using radiative-hydrodynamic simulations that regular patterns produced at the end of the AGB phase become highly distorted by their interactions with the expanding PN and the anisotropic illumination and ionization patterns caused by shadow instabilities. These processes will disrupt the regular (mostly spiral) patterns around AGB stars, plausibly becoming the arcs and fragmented rings observed in the haloes of PNe.
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Abunayib, Salah. "Alternative explanation of some total so-lar eclipse related phenomena." International Journal of Advanced Astronomy 5, no. 2 (September 28, 2017): 83. http://dx.doi.org/10.14419/ijaa.v5i2.8263.

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Diamond ring, shadow bands and coronal heating are some phenomena of great interest to concerned scientists and observers during total eclipse of the sun. These phenomena are explained here in a different way which is simply based on the familiar fact that the sun and the moon are actually spherical objects and not just plane disks. Firstly, the diamond of the diamond ring is seen here as two symmetrical seamless joined halves. One-half is the directly seen single spot of the sun that is uncovered by the moon just at the beginning and end of totality. The other half is a mirror image of that spot reflected by the edge surface of the moon. Secondly, the shadow bands phenomenon is explained as due to interference of light from two seamless joined hair crescents. One is the inner edge of the thin crescent sun that can be seen immediately before and after totality. Light from this inner edge hair crescent falling on the edge surface of the moon gets mirror reflected creating another hair crescent image and both are seamlessly embraced by the main crescent sun. Thirdly, during totality when looking at the outer atmosphere of the sun around its eclipsed face, one is actually looking through a very deep transparent atmosphere of the sun. The viewed depth in the outer atmosphere is geometrically hundreds of times greater than that of the photosphere at the center of the face of the sun. Theoretically, the solar energy gets concentrated by the integral effect of all the points along the viewed depth. This may, hence, stand as one of the factors to be considered in explaining the peculiar phenomenon that the temperature increases as we go away from the surface of the sun.
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PAILLÈS, CHRISTINE, FLORENCE SYLVESTRE, JAIME ESCOBAR, ALAIN TONETTO, SYBILLE RUSTIG, and JEAN-CHARLES MAZUR. "Cyclotella petenensis and Cyclotella cassandrae, two new fossil diatoms from Pleistocene sediments of Lake Petén-Itzá, Guatemala, Central America." Phytotaxa 351, no. 4 (June 7, 2018): 247. http://dx.doi.org/10.11646/phytotaxa.351.4.1.

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While analyzing the fossil diatom flora in one of the longest paleolimnological records (core PI-6) from Lake Petén-Itzá, lowland Guatemala, we encountered Aulacoseira Thwaites, Cyclotella (Kützing) and Discostella (Cleve & Grunow) Houk & Klee species appearing successively in the record. Among them, two new species that are assigned to the genus Cyclotella are described herein. Cyclotella petenensis sp. nov. is characterised by a coarse striation marked by a shadow line and a tangentially undulate central area with an arc of central fultoportulae. Cyclotella cassandrae sp. nov. has an elliptically shaped valve, coarse striae and a scattered ring of central fultoportulae in the central area. Classification and differences to similar taxa in the genus Cyclotella are discussed.
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Schamp, Jutta. "Whose shadow is it? The representation of trauma and creativity in Anton Nimblett’s ‘Ring Games’ and ‘Sections of an Orange’." International Journal of Jungian Studies 10, no. 3 (February 8, 2018): 249–65. http://dx.doi.org/10.1080/19409052.2018.1507808.

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Intervening in the current debate about an overemphasis on the individual in classical psychoanalytic trauma theory and the demand for a prioritization of the group in postcolonial trauma studies, this article proposes that Anton Nimblett’s short stories ‘Ring Games’ and titular ‘Sections of an Orange’ from his 2009 collection invite a postcolonial, post-Jungian optic because they portray the devastating effects of a colonized creative unconscious on the characters’ Self, relationships, and the collective. Both short stories explore the traumatic impact of colonialism and neoliberalism on the development of the characters’ unconscious and consciousness, unveiling the obstacles to re-inscribing a traditional heteronormative, Euro- American image of masculinity; individuating as gay; and living an authentic life. Questioning the binary opposites of the individual and the group, both short stories gesture towards the importance of creative self-realization as one cornerstone of individual and collective health when healing the destructive impact of postcolonial and neoliberal power configurations.
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Terazaki, Carlos Renato Ticianelli, Cesar Rodrigo Trippia, Carlos Henrique Trippia, Maria Fernanda Sales Ferreira Caboclo, and Carla Regina Miranda Medaglia. "Synovial chondromatosis of the shoulder: imaging findings." Radiologia Brasileira 47, no. 1 (February 2014): 38–42. http://dx.doi.org/10.1590/s0100-39842014000100013.

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Synovial chondromatosis is a benign condition characterized by synovial proliferation and metaplasia, with development of cartilaginous or osteocartilaginous nodules within a joint, bursa or tendon sheath. In the shoulder, synovial osteochondromatosis may occur within the glenohumeral joint and its recesses (including the tendon sheath of the biceps long head), and in the subacromial-deltoid bursa. Such condition can be identified either by radiography, ultrasonography or magnetic resonance imaging, showing typical features according to each method. Radiography commonly shows ring-shaped calcified cartilages and periarticular soft tissues swelling with erosion of joint margins. Ultrasonography demonstrates hypoechogenic cartilaginous nodules with progressive increase in echogenicity as they become calcified, with development of posterior acoustic shadow in case of ossification. Besides identifying cartilaginous nodules, magnetic resonance imaging can also demonstrate the degree of synovial proliferation. The present study is aimed at describing the imaging findings of this entity in the shoulder.
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Evans, Jonathan. "The Ring and the Cross: Christianity and The Lord of The Rings, and: Light Beyond All Shadow: Religious Experience in Tolkien's Work (review)." Tolkien Studies 9, no. 1 (2012): 97–105. http://dx.doi.org/10.1353/tks.2012.0008.

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30

REATTO, L., and D. E. GALLI. "WHAT IS A ROTON?" International Journal of Modern Physics B 13, no. 05n06 (March 10, 1999): 607–16. http://dx.doi.org/10.1142/s0217979299000497.

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Many models of a roton in superfluid 4 He have been proposed over the years but no general consensus has been reached yet on the nature of such excitation. We present a number of new results relating to this question. We have developed an accurate representation of the wave function of such excitation which is based on a shadow function. This allows to treat the short range backflow effects in a non perturbative way. The theory gives results in quantitative agreement with experiment. Starting from such eigenstates of momentum we build wave–packets and study local quantities like density, momentum and vorticity. No model agrees with our results for the excitations in the roton minimum region because we find that the excitations have in a varying degree characters of single particle, of non quantized smoke ring and of collective excitation. We have also considered 4 He in two dimensions and we find similar results. In 2D we have studied also maxon and high frequency phonon wave–packets.
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GRIGORIEVA, NATALIE S. "THE EFFECT OF OCEAN CURRENT ON SOUND PROPAGATION." Journal of Computational Acoustics 02, no. 04 (December 1994): 441–51. http://dx.doi.org/10.1142/s0218396x94000257.

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The effect of medium motion on sound propagation in the ocean is investigated. In a moving fluid, the sound propagation is described by a system of seven linear partial differential equations for seven unknown elements of a sound wave. These are the sound pressure, the particle oscillation velocity in a sound wave as well as the changes of medium density, its entropy, and concentration of the salt caused by passage of a sound wave. In the case of stratified moving medium, the point source field is represented in the form of a sum of quasinormal waves. If the ocean perturbed by a current is weakly inhomogeneous along the horizontal direction, the modification of the well-known method of horizontal rays/vertical modes is used. The "effective" sound speed for the model of stratified ocean is introduced. It allows the qualitative estimation of the medium motion effect on sound propagation taking into account the deformation of the initial sound speed profile. A sequence of direct numerical simulations of sound propagation problems has been carried out for the Gulf Stream models. It is shown that a large-scale current may alter the nature of guided wave sound propagation. For example, a current may lead to noticeable strengthening of a near surface waveguide. It results in smoothed field pattern and significant illumination of the shadow zones. Taking account of the medium inhomogeneity along the horizontal direction leads to the shift of the shadow zones and the illuminated domains relative to the source. If a sound path crosses the Gulf Stream ring, the medium motion effect on sound propagation may be ignored.
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Pysz, K., I. Zychor, T. Hermes, M. Hartmann, H. Ohm, P. Kulessa, W. Borgs, et al. "Measurement of the lifetime of heavy Λ hypernuclei with the recoil shadow method and internal targets in the storage ring COSY-Jülich." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 420, no. 1-2 (January 1999): 356–65. http://dx.doi.org/10.1016/s0168-9002(98)00784-0.

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Baloglu, Bora, Wei Lin, Ken Stratton, Miguel Jimarez, and Danny Brady. "Warpage Characterization and Improvements for IC Packages with Coreless Substrate." International Symposium on Microelectronics 2013, no. 1 (January 1, 2013): 000260–64. http://dx.doi.org/10.4071/isom-2013-tp25.

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Coreless package substrates are preferred for their superior electrical performance and thin profile compare to conventional substrates with core. However, one of the major concerns with coreless substrate packages is warpage control. It is difficult to meet industry standards for co-planarity because of the high CTE of the coreless substrates and the missing stiff core material in the stack up of the coreless structure. Finite element analysis (FEA) is utilized to investigate the use of coreless substrate in different package configurations. In this study, known stiffening structures such as a stiffener ring, lid and molding options are investigated to characterize the advantages and disadvantages of using each of these structures to control the warpage in an IC package with coreless substrate. Available shadow moiré data is used for initial correlation of the finite element model and further design changes were carried out to stiffen the structure in the final packaged configuration. It is important to understand and make design considerations accordingly to improve assembly yield. Suggestions made depend on the FEA findings which would guide the selection of the stiffening structure for a package with coreless substrate.
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Pankotai, T., C. Popescu, D. Martín, B. Grau, N. Zsindely, L. Bodai, L. Tora, A. Ferrús, and I. Boros. "Genes of the Ecdysone Biosynthesis Pathway Are Regulated by the dATAC Histone Acetyltransferase Complex in Drosophila." Molecular and Cellular Biology 30, no. 17 (June 28, 2010): 4254–66. http://dx.doi.org/10.1128/mcb.00142-10.

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ABSTRACT Uncovering mechanisms that regulate ecdysone production is an important step toward understanding the regulation of insect metamorphosis and processes in steroid-related pathologies. We report here the transcriptome analysis of Drosophila melanogaster dAda2a and dAda3 mutants, in which subunits of the ATAC acetyltransferase complex are affected. In agreement with the fact that these mutations lead to lethality at the start of metamorphosis, both the ecdysone levels and the ecdysone receptor binding to polytene chromosomes are reduced in these flies. The cytochrome genes (spookier, phantom, disembodied, and shadow) involved in steroid conversion in the ring gland are downregulated, while the gene shade, which is involved in converting ecdysone into its active form in the periphery, is upregulated in these dATAC subunit mutants. Moreover, driven expression of dAda3 at the site of ecdysone synthesis partially rescues dAda3 mutants. Mutants of dAda2b, a subunit of the dSAGA histone acetyltransferase complex, do not share phenotype characteristics and RNA profile alterations with dAda2a mutants, indicating that the ecdysone biosynthesis genes are regulated by dATAC, but not by dSAGA. Thus, we provide one of the first examples of the coordinated regulation of a functionally linked set of genes by the metazoan-specific ATAC complex.
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Harwood, Richard. "Planning and Compulsory Purchase Act 2004 - Howthe Government Takes Control Ofplanning Policy." Environmental Law Review 7, no. 2 (June 2005): 124–29. http://dx.doi.org/10.1177/146145290500700204.

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‘Three Rings for the Elven-kings under the sky, seven for the Dwarf-lords in their halls of stone, nine for Mortal Men doomed to die, one for the Dark Lord on his dark throne in the Land of Mordor where the Shadows lie. One Ring to rule them all, one Ring to find them, one Ring to bring them all and in the darkness bind them'
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De-Deus, Gustavo, Miriam Z. Scelza, Prasanna Neelakantan, Subash Sharma, Aline de Almeida Neves, and Emmanuel João Nogueira Leal Silva. "Three-dimensional Quantitative Porosity Characterization of Syringe- versus Hand-mixed Set Epoxy Resin Root Canal Sealer." Brazilian Dental Journal 26, no. 6 (December 2015): 607–11. http://dx.doi.org/10.1590/0103-6440201300074.

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The aim of the present study was to compare the porosity characteristics of AH Plus Jet(tm) syringe-mix and the conventional hand-mixed AH Plus root canal sealers by three-dimensional quantitative high-resolution micro-computed tomography (micro-CT). Seven test specimens were prepared from each tested sealer by a single operator following the manufacturer's instructions and poured into pre-lubricated plastic split-ring moulds. Set sealer test specimens were scanned using a micro-CT device and the shadow images were reconstructed into cross-sectional slices. The evaluated parameters were (i) total pore count, (ii) total pore volume and mean pore volume, (iii) total porosity (% of pore volume in relation to total sealer volume) and (iv) mean pore distance to the sealer lateral external surface. In both groups, most pores were localized within the external sealer perimeter (0.05 mm from the external surface). Hand-mixed AH Plus specimens showed statistically significant higher mean total pore count, total pore volume and total porosity (p=0.001) than the syringe-mixed specimens. However, mean pore sizes in AH Plus syringe-mixed specimens were significantly higher (p=0.046) than the AH Plus hand-mixed counterparts. Hand-mixed AH Plus was associated with higher total mean pore count, volume and total porosity compared to syringe mixed AH Plus.
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Muro-Arena, G. A., C. Dominik, L. B. F. M. Waters, M. Min, L. Klarmann, C. Ginski, A. Isella, et al. "Dust modeling of the combined ALMA and SPHERE datasets of HD 163296." Astronomy & Astrophysics 614 (June 2018): A24. http://dx.doi.org/10.1051/0004-6361/201732299.

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Context. Multiwavelength observations are indispensable in studying disk geometry and dust evolution processes in protoplanetary disks. Aims. We aim to construct a three-dimensional model of HD 163296 that is capable of reproducing simultaneously new observations of the disk surface in scattered light with the SPHERE instrument and thermal emission continuum observations of the disk midplane with ALMA. We want to determine why the spectral energy distribution of HD 163296 is intermediary between the otherwise well-separated group I and group II Herbig stars. Methods. The disk was modeled using the Monte Carlo radiative transfer code MCMax3D. The radial dust surface density profile was modeled after the ALMA observations, while the polarized scattered light observations were used to constrain the inclination of the inner disk component and turbulence and grain growth in the outer disk. Results. While three rings are observed in the disk midplane in millimeter thermal emission at ~80, 124, and 200 AU, only the innermost of these is observed in polarized scattered light, indicating a lack of small dust grains on the surface of the outer disk. We provide two models that are capable of explaining this difference. The first model uses increased settling in the outer disk as a mechanism to bring the small dust grains on the surface of the disk closer to the midplane and into the shadow cast by the first ring. The second model uses depletion of the smallest dust grains in the outer disk as a mechanism for decreasing the optical depth at optical and near-infrared wavelengths. In the region outside the fragmentation-dominated regime, such depletion is expected from state-of-the-art dust evolution models. We studied the effect of creating an artificial inner cavity in our models, and conclude that HD 163296 might be a precursor to typical group I sources.
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Ferreira, Denise Helena Lombardo, Tadeu Fernandes De Carvalho, and Sandro Joel Mariano De Oliveira. "Um Estudo Sobre o Matemático Português Pedro Nunes." Jornal Internacional de Estudos em Educação Matemática 13, no. 1 (June 22, 2020): 94–102. http://dx.doi.org/10.17921/2176-5634.2020v13n1p94-102.

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Trata-se de um artigo que tem por objetivo estudar as obras do matemático português Pedro Nunes, ou Petrus Nonius, destacando a obra intitulada Libro de Algebra em Arithmetica y Geometria. Para a elaboração deste trabalho foram usados informações e dados que se encontram disponíveis na internet e na literatura científica. Foram estudados os métodos de resolução de equações, para os quais Nunes usava tanto a álgebra quanto a geometria para suas demonstrações, além dos conhecimentos aprofundados dos livros de Euclides, os Elementos. Além disso, Nunes criou diversos instrumentos de medida, dentre os quais, anel náutico, instrumento de sombras e o nônio, mencionados neste trabalho. Palavras-chave: Pedro Nunes. Álgebra. Geometria. Instrumentos de Navegação. Abstract It is an article that aims to study the works of the Portuguese mathematician Pedro Nunes, or Petrus Nonius, highlighting the work entitled Book of Algebra in Arithmetic and Geometry. For the elaboration of this work, information and data were used that are available in the internet and in the scientific literature. Methods for solving equations were studied, for which Nunes used both algebra and geometry for his demonstrations, as well as the in-depth knowledge of Euclid's books, the Elements. In addition, Nunes created several measuring instruments, among them, nautical ring, shadow instrument and the vernier, mentioned in this work. Keywords: Pedro Nunes. Algebra. Geometry. Navigation instruments.
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Zamadei, Tamara, Adilson Pacheco de Souza, Frederico Terra de Almeida, and João Franscisco Escobedo. "Radiação global e difusa diária na região de transição Cerrado-Amazônia brasileira." Ciência e Natura 43 (April 15, 2021): e37. http://dx.doi.org/10.5902/2179460x39775.

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This study aimed to analyze the seasonal variations in atmospheric transmissivity and solar radiation (global and diffuse) on the horizontal surface in Sinop, Mato Grosso (MT) (11.865°S, 55.485°W, and altitude of 371 m) from 06/02/2011 to 12/31/2014. The values of diffuse radiation were measured using the Melo-Escobedo-Oliveira (MEO) shadow ring, with application of astronomical, geometric, and anisotropic correction factors. The analysis of atmospheric transmissivity was based on the classification of sky cover as cloudy, partly cloudy, partially clear, or clear. The diffuse radiation showed similar behavior to the radiation at the top of the atmosphere, reaching a maximum between October and April (rainy season), while the global radiation displayed higher levels during the dry season (May to September). The average daily global radiation ranged from 22.75±0.61 MJ m−2 d−1 in August to 16.44±1.45 MJ m−2 d−1 in January. In Sinop, cloudy and partly cloudy skies occurred on 45.6% of days and atmospheric transmissivity of global radiation was greater than 55% on 54.6% of days. The variations in diffuse radiation in the region were influenced by cloudiness and the concentration of biomass burning aerosol particles. The diffuse radiation can represent 8.02%–99.12% of the global radiation and 5.33%–29.01% of solar energy incident at the top of the atmosphere.
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Casassus, Simon, Sebastián Pérez, Axel Osses, and Sebastián Marino. "Cooling in the shade of warped transition discs." Monthly Notices of the Royal Astronomical Society: Letters 486, no. 1 (April 27, 2019): L58—L62. http://dx.doi.org/10.1093/mnrasl/slz059.

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ABSTRACT The mass of the gaseous reservoir in young circumstellar discs is a crucial initial condition for the formation of planetary systems, but estimates vary by orders of magnitude. In some discs with resolvable cavities, sharp inner disc warps cast two-sided shadows on the outer rings; can the cooling of the gas as it crosses the shadows bring constraints on its mass? The finite cooling time-scale should result in dust temperature decrements shifted ahead of the optical/IR shadows in the direction of rotation. However, some systems show temperature drops, while others do not. The depth of the drops and the amplitude of the shift depend on the outer disc surface density Σ through the extent of cooling during the shadow crossing time, and also on the efficiency of radiative diffusion. These phenomena may bear observational counterparts, which we describe with a simple 1D model. An application to the HD 142527 disc suggests an asymmetry in its shadows, and predicts a ≳10 deg shift for a massive gaseous disc, with peak Σ > 8.3 g cm−2. Another application to the DoAr 44 disc limits the peak surface density to Σ < 13 g cm−2.
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Kudish, Avraham I., and Efim G. Evseev. "The assessment of four different correction models applied to the diffuse radiation measured with a shadow ring using global and normal beam radiation measurements for Beer Sheva, Israel." Solar Energy 82, no. 2 (February 2008): 144–56. http://dx.doi.org/10.1016/j.solener.2007.06.006.

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42

Ash, H. E., and A. Unsworth. "Proximal Interphalangeal Joint Dimensions for the Design of a Surface Replacement Prosthesis." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 210, no. 2 (June 1996): 95–108. http://dx.doi.org/10.1243/pime_proc_1996_210_398_02.

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The bones from 83 proximal interphalangeal joints (PIPJs) were dissected in order to determine the shape and size of the articular surfaces. The bones were modelled in acrylic dental bone cement and the original bones and replicas were then sectioned and shadow-graphed. Dimensions were taken from these shadowgraphs to be used in the design of a surface replacement prosthesis for the PIPJ. It was found that the bi-condylar heads of the proximal and middle phalanges were circular in the sagittal plane as was the base of the middle phalanx. However, the radius of curvature of the middle phalangeal base was greater than that of the proximal phalangeal head indicating that the PIPJ is not a conforming joint. The alignment of the radial and ulnar condyles of the proximal phalangeal bones was investigated and it was found that the index and middle finger bones tended to have a more prominent ulnar condyle while the ring and little finger bones tended to have a more prominent radial condyle. This was due to a slight difference in diameters of the two condyles. The proximal phalangeal bone lengths L ranged from 29–52 mm, maximum head widths W from 8.5–15.5 mm and maximum diameters D of the best-fit circles to the sagittal profile of the bone head from 6–11 mm. The middle phalangeal bone lengths ranged from 16–35 mm, maximum head widths from 8.5–12 mm and maximum diameters from 5–7.5 mm. The relationships and ratios between these dimensions for the proximal and middle phalanges have been calculated.
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Spilker, Linda J. "Shadows of Saturn’s B ring." Nature Astronomy 1, no. 9 (September 2017): 577. http://dx.doi.org/10.1038/s41550-017-0254-6.

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44

Kraus, Stefan, Alexander Kreplin, Alison K. Young, Matthew R. Bate, John D. Monnier, Tim J. Harries, Henning Avenhaus, et al. "A triple-star system with a misaligned and warped circumstellar disk shaped by disk tearing." Science 369, no. 6508 (September 3, 2020): 1233–38. http://dx.doi.org/10.1126/science.aba4633.

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Young stars are surrounded by a circumstellar disk of gas and dust, within which planet formation can occur. Gravitational forces in multiple star systems can disrupt the disk. Theoretical models predict that if the disk is misaligned with the orbital plane of the stars, the disk should warp and break into precessing rings, a phenomenon known as disk tearing. We present observations of the triple-star system GW Orionis, finding evidence for disk tearing. Our images show an eccentric ring that is misaligned with the orbital planes and the outer disk. The ring casts shadows on a strongly warped intermediate region of the disk. If planets can form within the warped disk, disk tearing could provide a mechanism for forming wide-separation planets on oblique orbits.
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45

Baloglu, Bora, Miguel Jimarez, and Ahmer Syed. "Groove Geometry and Mold Shrinkage Effects on Die Stress in Flip Chip Molded BGAs (FCMBGA)." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, DPC (January 1, 2013): 000455–70. http://dx.doi.org/10.4071/2013dpc-ta23.

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Exposed die flip chip molded BGA (FCMBGA) packages are preferred for their improved thermal performance and reduced system cost. In this package type, mold compound replaces the traditional capillary underfill and also provides a better stiffening option for the package without the need for additional structural support such as lid and/or stiffening ring. In addition, it allows better utilization of the board real estate as the passive components can be placed closer to the die. Groove or an undercut is the shape of the mold around the exposed die that is formed during the molding process. To ensure a mold-free top surface of the die, a seal (soft insert) that has a larger surface area than the die is being used to cover the die top surface. This larger portion of the seal outlines the groove geometry when it is compressed on top of the die. Seal size can be designed to establish certain groove geometry. Thus, it is important to characterize/understand the effects of the groove geometry as it is a design parameter and can be adjusted to create more robust molded packages. In this study, specific groove width and depth values for various package configurations are investigated using finite elements analysis, FEA. Initially, a detailed finite element model is prepared and warpage simulation is performed. Model correlation to the actual Shadow Moiré is obtained. Then, using the correlated finite element model, die back side stress and shear stresses, where die faces mold compound, are obtained for a thermal cool down simulation from the molding temperature. Mold compound shrinkage is also considered by using an adjusted thermal expansion coefficient value. As a validation study, a test mold chase/tool for varying insert sizes has been designed and, molded packages with different groove geometries and different mold compounds were build. Using the correlation between the test data and the simulation results an order of importance (based on the groove geometry parameters and mold compound's material properties) will be presented which then, can be used as a design guideline to change the groove geometry to produce more robust molded packages.
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Siebenmorgen, R., and F. Heymann. "Shadows, gaps, and ring-like structures in protoplanetary disks." Astronomy & Astrophysics 539 (February 20, 2012): A20. http://dx.doi.org/10.1051/0004-6361/201118493.

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DOUGHERTY, Steven T. "Generalized shadows of codes over rings." Hokkaido Mathematical Journal 32, no. 1 (February 2003): 101–16. http://dx.doi.org/10.14492/hokmj/1350652413.

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48

Hamilton, Douglas P., and Harald Krüger. "The sculpting of Jupiter’s gossamer rings by its shadow." Nature 453, no. 7191 (May 2008): 72–75. http://dx.doi.org/10.1038/nature06886.

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49

Rud, V. S., R. Hofmann, V. A. Kosakivskyi, O. V. Zaitseva, and J. Muller. "BILYI KAMIN: SITE STRUCTURE OF THE BIGGEST TRYPILLIA CULTURE SETTLEMENT OF THE SOUTHERN BUH-DNISTER INTERFLUVE." Archaeology and Early History of Ukraine 33, no. 4 (December 25, 2019): 362–72. http://dx.doi.org/10.37445/adiu.2019.04.28.

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So far research effort regarding Cucuteni—Trypillia mega-sites was to a large extent focussed on the region in the east of the Southern Buh. In contrast, the Southern Buh-Dnister interfluve stands for long time in the shadow of its eastern neighbour. To improve this situation and to gain a better understanding of the macro-regional variability within the Cucuteni—Trypillia cultural complex, in spring 2018 the exploration of the large CTCC site Bilyi Kamin was started by an international team of researchers from Kiel University (Germany) and Institute of Archaeology of the National Academy of Science of Ukraine (Kyiv, Ukraine) which is the largest settlement in this region. Magnetometry in total size of 40.6 ha have been performed using the MAGNETO® MX V3 Survey System of the company SENSYS Sensorik & Systemtechnologie GmbH Bad Saarow (Germany). During our survey large areas in the south, north and near the centre of the site were measured. Based on these data the total extension of the site can be estimated to approximately 97 ha. Different categories of magnetic anomalies can be identified in Bilyi Kamin: 297 rectangular anomalies, which are the ruins of intensively burnt clay houses; 141 rectangular anomalies of houses, burnt with less intensity or eroded; four rectangular anomalies of unique buildings, so-called «megastructures»; 351 anomaly of different-shape objects, most of which can be interpreted as pits; 12 stretched objects, presumably road to the south of the site; linear anomaly of the ditch or natural gully to the north-west from north part of outer circle. The site is built in two circles of houses. The ring corridor between the circles is free from buildings. Some buildings are located outside the circles as well. They are grouped as short lines radial and parallel in respect to the circles. The space inside the circles is built partially. In the north and north-west parts of the site the buildings are grouped mostly in long radial lines. In the south part of the site the number of buildings inside the circles is smaller. This might indicate a heterogeneous character of the population or changes in the development plan. The anomalies of pits from Bilyi Kamin are usually located near the buildings, at side or ending walls. Some groups of pits are not connected to the buildings. It is also possible that some of anomalies of pits, having largest nT values can represent other kind of objects — as for example pottery kilns. In Bilyi Kamin three elongated mega-structures with lengths between 36 and 64 m and widths between 8 and 11.5 m are placed on the 420 Ч (>150) m measuring square (so-called «plaza»). The partly staggered arrangement of these constructions might suggest that they were not built simultaneously but represent a sequence of successively used buildings. Within the concentric ring corridor directly beside of the central plaza, additionally a fourth mega-structure is visible. For the planning of the settlement layout, the placement of a rectangular square on top of the promontory with three large buildings played potentially an important role. These mega-structures and the associated plaza most likely formed the architectural arena of central integrative institutions for decision-making, integrative ritual action, and surplus-consumption at the level of the entire settlement.
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Garufi, A., M. Benisty, P. Pinilla, M. Tazzari, C. Dominik, C. Ginski, Th Henning, et al. "Evolution of protoplanetary disks from their taxonomy in scattered light: spirals, rings, cavities, and shadows." Astronomy & Astrophysics 620 (December 2018): A94. http://dx.doi.org/10.1051/0004-6361/201833872.

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Context. Dozens of protoplanetary disks have been imaged in scattered light during the last decade. Aims. The variety of brightness, extension, and morphology from this census motivates a taxonomical study of protoplanetary disks in polarimetric light to constrain their evolution and establish the current framework of this type of observation. Methods. We classified 58 disks with available polarimetric observations into six major categories (Ring, Spiral, Giant, Rim, Faint, and Small disks) based on their appearance in scattered light. We re-calculated the stellar and disk properties from the newly available Gaia DR2 and related these properties with the disk categories. Results. More than half of our sample shows disk substructures. For the remaining sources, the absence of detected features is due to their faintness, their small size, or the disk geometry. Faint disks are typically found around young stars and typically host no cavity. There is a possible dichotomy in the near-infrared (NIR) excess of sources with spiral-disks (high) and ring-disks (low). Like spirals, shadows are associated with a high NIR excess. If we account for the pre-main sequence evolutionary timescale of stars with different mass, spiral arms are likely associated with old disks. We also found a loose, shallow declining trend for the disk dust mass with time. Conclusions. Protoplanetary disks may form substructures like rings very early in their evolution but their detectability in scattered light is limited to relatively old sources ( ≳5 Myr) where the recurrently detected disk cavities cause the outer disk to be illuminate. The shallow decrease of disk mass with time might be due to a selection effect, where disks observed thus far in scattered light are typically massive, bright transition disks with longer lifetimes than most disks. Our study points toward spirals and shadows being generated by planets of a fraction of a Jupiter mass to a few Jupiter masses in size that leave their (observed) imprint on both the inner disk near the star and the outer disk cavity.
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