(Phys.org) —A pair of Australian researchers studying rock samples has found evidence to suggest that the Earth’s tectonic plate activity peaked approximately 1.1 billion years ago. In their paper published in the journal Geology, Martin Van Kranendonk and Christopher Kirkland describe the results of their analysis of a multitude of rock samples from various sites around the world. Studying ancient Earth’s geochemistry © 2013 Phys.org Explore further More information: Orogenic climax of Earth: The 1.2–1.1 Ga Grenvillian superevent, Geology, First published online April 29, 2013, doi: 10.1130/G34243.1AbstractThe rate of growth of the continental crust is controversial. We present an evaluation of time-constrained analyses of oxygen isotopes in zircon grains and incompatible element (Zr, Th) concentrations in magmatic rocks to test for variations in the degree of crustal recycling through geological time. The data indicate a rise in these geochemical proxies from ca. 3.0 Ga to a statistically significant peak at 1.2–1.1 Ga during the amalgamation of supercontinent Rodinia, and a decrease thereafter. When combined with other geological and geophysical observations, the data are interpreted as a consequence of an unprecedented level of crustal recycling and sediment subduction during Rodinia assembly, arising from a “Goldilocks” (i.e., just right) combination of larger, thicker plates on a warmer Earth with more rapid continental drift relative to modern Earth. The subsequent decrease in δ18O, Zr, and Th measurements is interpreted to reflect decreasing drift rates on a cooling Earth.via Newscientist Citation: Geologic study suggests Earth’s tectonic activity peaked 1.1 billion years ago (2013, May 8) retrieved 18 August 2019 from https://phys.org/news/2013-05-geologic-earth-tectonic-peaked-billion.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Journal information: Geology Scientists agree that the Earth’s tectonic plates have been shifting for at least 3 billion years, but no one really knows whether such shifting has been getting more or less active. In this new effort Kranendonk and Kirkland undertook an exhaustive study of rock samples to learn more.The two first looked at 3200 samples of rocks collected by various researchers over the years, taken from various points around the world. Specifically, they were looking for the amount of zirconium and thorium in them—both have been found to be more common in rocks that were formed during tectonically active periods. Next they looked at an additional 1200 rock samples, this time looking for oxygen isotopes, which are also known to be more common in rocks created during times of high tectonic activity.In analyzing the data obtained from studying the rocks, the researchers found evidence that suggests that tectonic activity increased from a time approximately 3 billion years ago. That activity continued to increase, they say, for 2 billion years, peaking around 1.1 billion years ago—a time during which all of the continents had merged into one supercontinent called Rodinia. Since that time, they note, it appears that tectonic activity has been slowing. This suggests that the planet has a lifespan.The rocks can’t offer any evidence to explain why there was an increase in activity or why it has been slowing after peaking, but the researchers have a theory—they believe that prior to the increase in tectonic activity, tectonic plates the world over became thicker, and likely larger. This meant collisions between plates would have been far more violent than before. As the Earth cooled off, the plates would have moved slower causing less activity overall. These new findings also suggest that at some point the Earth’s plates will stop moving altogether—though how long that might take is still a mystery.
More information: www.takanishi.mech.waseda.ac.j … top/research/wabian/via IEEE Spectrum © 2013 Phys.org Explore further Their work on WABIAN has been in step with the Japan government’s concern about technology for an aging population, to preserve a decent quality of life for the aging, despite limitations on freely moving about that may result from old age. The team stated in the past that a robot as “a human’s partner” would provide daily robotic assistance, and that kind of application was more in their line of view than an industrial robot earmarked for highly specified and constrained applications. To accomplish the task, robots have to be able to move in indoor and outdoor conditions, they said, and biped humanoid robots are best suited for this. They also noted that aside from robots as human assistants, there was a need for evaluation methods for assistive equipment, dependent on human body measurements. A biped humanoid robot optimized to serve as a human motion simulator is a step in the right direction. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. In their latest workup of the WABIAN robot, now called WABIAN-2RIII.the researchers redesigned lower legs, after studying humans walking. They analyzed the average size and movement range in humans, and analyzed motion-capture data to decide on the best performance requirements.The researchers, T. Otani, A. Iizuka, D. Takamoto, H. Motohashi, T. Kishi, P. Kryczka, N. Endo, L. Jamone, K. Hashimoto, T. Takashima, H.O. Lim, and A. Takanishi, discuss their work in the paper presented at ICRA. The paper is titled, “New Shank Mechanism for Humanoid Robot Mimicking Human-like Walking in Horizontal and Frontal Plane.” According to IEEE Spectrum, they had the following results: In tests of walking in place, (1) they were able to match the human step time of 0.6 seconds; (2) they matched the required 12-degree foot rotation and 90-mm step width; (3) they successfully reduced its center of mass lateral movement from 50 mm down to 34 mm. The researchers only conducted standing tests, with walking in place, and switching balance from foot to foot. In the future, the researchers intend to work on the robot’s forward walking. Robots learn to take a proper handoff by following digitized human examples Citation: WABIAN robot from Japan steps closer to human walk (2013, June 2) retrieved 18 August 2019 from https://phys.org/news/2013-06-wabian-robot-japan-closer-human.html (Phys.org) —Researchers designing adult bipedal robots have faced a challenge in limitations in a robot’s walking pattern. They seek ways to improve on designs to have robots move more naturally. Improving the walking function has been the goal of researchers at the Humanoid Robotics Institute at Waseda University in Japan. Last month, led by Professor Atsuo Takanishi, the team presented the results of their efforts at the IEEE International Conference on Robotics and Automation (ICRA) in Germany. What they achieved more closely replicates normal human foot movements than before. The Institute’s researchers turned to their humanoid robot, WABIAN-2R (WAseda BIpedal humANoid – No. 2 Refined), which already had a flexible pelvis, and stretched knees. WABIAN-2R’s feet also had the distinction of a curving arch and flexible toes, landing heel-first and lifting off at its toes, noted the IEEE Spectrum report. The robot is under 5 feet tall (148 cm), and weighs 64 kg (141 pounds), with 41 degrees of freedom.
Hubble uncovers a galaxy pair coming in from the wilderness Citation: Researchers discover UGC 3672 galaxy to be an unusual merging triplet of gas-rich dwarf galaxies (2016, November 8) retrieved 18 August 2019 from https://phys.org/news/2016-11-ugc-galaxy-unusual-merging-triplet.html UGC 3672 is located near the center of the nearby Lynx-Cancer intergalactic void. This void, which is about 59 million light years away from Earth, was recently a subject of detailed surveys due to its relative proximity. Lynx-Cancer gives scientists the opportunity to study galaxies to a much fainter mass and luminosity limit than have been done in more distant voids.In September 2015, a team of researchers, led by Jayaram Chengalur of the National Center for Radio Astrophysic in Pune, India, conducted observations of UGC 3672 lasting approximately five hours. They used the Giant Metrewave Radio Telescope (GMRT) located near Pune to carry out hydrogen line (H I line) observations of UCG 3672 and also analyzed the optical photometry data available in the the Sloan Digital Sky Survey (SDSS) in order to study this peculiar galaxy in detail.The data investigated by the team allowed them to draw conclusions that UGC 3672 is, indeed, a triplet of gas-rich dwarf galaxies.”We find that UGC 3672 consists of an approximately linearly aligned triplet of gas rich dwarfs with large scale velocity continuity along the triplet axis,” the scientists wrote in the paper.According to the research, the faintest component of the triplet, designated UGC 3672A, is extremely gas-rich and also extremely metal deficient. UGC 3672B and UGC 3672C are significantly less gas-rich, four and six times less gas-rich respectively. It is also noteworthy that star formation is much more wide spread in ‘B’ and ‘C’ rather than in the ‘A’ dwarf.Based on the observations, the astronomers assume that the location of the UGC 3672 system in an extremely low-density environment is not coincidental, but is rather a consequence of structure formation proceeding more slowly.”We suggest that the location of this highly unusual system is not a coincidence but is related to the ‘cosmic microscope and time machine’ effects associated with voids,” the paper reads.Intergalactic voids are regarded by astronomers as such “cosmic microscopes and time machines” as they offer an opportunity to look at both the earlier stages of structure formation. Furthermore, voids allow probing smaller scales of the power spectrum than is probed by structures in dense regions.The study also confirms that the so-called “wet” mergers (mergers between gas-rich galaxies) could produce gas-rich disks. The authors note that in the case of UGC 3672, the linear arrangement and velocity continuity of the galaxies in this system, along with the fact that the diffuse gas appears to be settling into a rotating disk, indicate that a wet merger with flow along filaments is a possible pathway for the formation of gas-rich disks.”Our observations indicate that wet mergers of galaxies flowing along a filament is a possible pathway for the production of disk like systems,” the researchers wrote. Left: An overlay of the Hi velocity field at 8.′′1 × 5.′′5 (contours) on the KPNO 0.9m B-band image of UGC 3672A. The overall North-South extent of the very low surface brightness optical emission is ∼40′′. A faint foreground star is also seen superposed on the diffuse optical emission. A change in the direction of the gradient of the Hi velocity field around U3672A can also be seen. Right: An greyscale representation of the second moment of the Hi distribution at 8.′′1 × 5.′′5. The beam size is shown in the lower left corner. An increase in the velocity dispersion around U3672A can be seen. Credit: Chengalur et al., 2016. Explore further (Phys.org)—Astronomers from India and Russia revealed new information about the composition of the galaxy UGC 3672. According to a paper published Nov. 4 on the arXiv pre-print server, UGC 3672 is actually a triplet of very gas-rich dwarf galaxies in the process of merging. More information: UGC 3672: An unusual merging triplet of gas-rich galaxies in the Lynx-Cancer void, arXiv:1611.01271 [astro-ph.GA] arxiv.org/abs/1611.01271AbstractWe present HI 21cm and optical observations of UGC 3672 which is located near the centre of the nearby Lynx-Cancer void. We find that UGC 3672 consists of an approximately linearly aligned triplet of gas rich dwarfs with large scale velocity continuity along the triplet axis. The faintest component of the triplet is extremely gas-rich (MHI/LB ~ 17) and also extremely metal deficient (12+log(O/H) ~ 7.0). The metallicity of this dwarf is close to the ‘floor’ observed in star forming galaxies. Low resolution HI images show that the galaxy triplet is located inside a common HI envelope, with fairly regular, disk like kinematics. At high angular resolution however, the gas is found to be confined to several filamentary tidal tails and bridges. The linear alignment of the galaxies, along with the velocity continuity that we observe, is consistent with the galaxies lying along a filament. We argue that the location of this highly unusual system in an extremely low density environment is not a coincidence, but is a consequence of structure formation proceeding more slowly and also probing smaller scales than in regions with average density. Our observations also indicate that wet mergers of galaxies flowing along filaments is a possible pathway for the formation of gas rich disks. The UGC 3672 system provides an interesting opportunity to study the kind of interactions typical between high redshift extremely gas rich unevolved small systems that lie at base of the hierarchical galaxy formation model. © 2016 Phys.org This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. More information: Daniel T. Ksepka et al. Early Paleocene landbird supports rapid phylogenetic and morphological diversification of crown birds after the K–Pg mass extinction, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1700188114AbstractEvidence is accumulating for a rapid diversification of birds following the K–Pg extinction. Recent molecular divergence dating studies suggest that birds radiated explosively during the first few million years of the Paleocene; however, fossils from this interval remain poorly represented, hindering our understanding of morphological and ecological specialization in early neoavian birds. Here we report a small fossil bird from the Nacimiento Formation of New Mexico, constrained to 62.221–62.517 Ma. This partial skeleton represents the oldest arboreal crown group bird known. Phylogenetic analyses recovered Tsidiiyazhi abini gen. et sp. nov. as a member of the Sandcoleidae, an extinct basal clade of stem mousebirds (Coliiformes). The discovery of Tsidiiyazhi pushes the minimum divergence ages of as many as nine additional major neoavian lineages into the earliest Paleocene, compressing the duration of the proposed explosive post–K–Pg radiation of modern birds into a very narrow temporal window parallel to that suggested for placental mammals. Simultaneously, Tsidiiyazhi provides evidence for the rapid morphological (and likely ecological) diversification of crown birds. Features of the foot indicate semizygodactyly (the ability to facultatively reverse the fourth pedal digit), and the arcuate arrangement of the pedal trochleae bears a striking resemblance to the conformation in owls (Strigiformes). Inclusion of fossil taxa and branch length estimates impacts ancestral state reconstructions, revealing support for the independent evolution of semizygodactyly in Coliiformes, Leptosomiformes, and Strigiformes, none of which is closely related to extant clades exhibiting full zygodactyly. Journal information: Proceedings of the National Academy of Sciences Ryan Williamson (left) and Taylor Williamson (right), the twin sons of Thomas Williamson, discovered the fossil site while on a weekend fossil collecting trip with their father when they were 11 years old. Credit: Thomas Williamson. Fossil bones of Tsidiiyazhi abini, a 62.5 million-year-old fossil representing the oldest arboreal species of crown bird. Credit: Thomas Stidham Citation: New species of ancient bird discovered in New Mexico (2017, July 11) retrieved 18 August 2019 from https://phys.org/news/2017-07-species-ancient-bird-mexico.html Explore further Approximately 65 million years ago, planetary scientists believe, a large asteroid struck the Earth near what is now the Yucatan Peninsula. The impact and its aftermath were so massive that it caused the extinction of approximately 70 percent of plants and animals on the planet. Scientists have been able to piece together what happened to many land animals in the millions of years after the great extinction, but little progress has been made regarding birds. Because their bones are smaller and more fragile, birds do not fossilize as well as other animals. Thus, they leave behind fewer traces of their existence. That is why the new find is so important—because it is helping to fill in the phylogenetic tree.The discovery of the fossil (which the team has named Tsidiiyazhi abini) was actually made by Ryan and Taylor Williamson, 11-year-old twin sons of co-author Thomas Williamson, as the family was out on a fossil hunting expedition. The father and his colleagues returned to the site to unearth the fossil remains and then to study them. They were not in good shape, the team reports, but there was enough material to get a feel for what the bird looked like. The team was also able to date the fossil and to compare it with the few other fossils that have been found in other locations from roughly the same time period. That allowed the team to flesh out the family tree to include as many as 10 major bird groups existing as early as four million years after the great extinction—much earlier than previously believed. The bird was dated to approximately 62 to 65 million years ago, which, the team notes, suggested birds recovered rapidly from the asteroid strike. They note also that the bird closely resembles the modern mousebird, and had the unique ability to turn its fourth toe. This allowed it to turn its body completely about-face—a feature seen with modern owls. © 2017 Phys.org Artist’s rendering of Tsidiiyazhi abini. Credit: Sean Murtha. Group builds most comprehensive family tree of birds to date (Phys.org)—A new species of ancient bird has been discovered by a trio of researchers working in the New Mexico desert—its fossilized remains were found in the Nacimiento Formation in the San Juan Basin. In their paper published in Proceedings of the National Academy of Sciences, Daniel Ksepka with the Bruce Museum, Thomas Stidham with the Chinese Academy of Sciences and Thomas Williamson with the New Mexico Museum of Natural History describe the fossil that was found and how it contributes to better understand bird evolution after the massive die-off that led to the extinction of most of the dinosaurs.
A pair of researchers at Yale University has found evidence that suggests the Devonian Nekton Revolution never actually occurred. In their paper published in Proceedings of the Royal Society B, Christopher Whalen and Derek Briggs describe their study and what they believe actually happened in the world’s oceans during the Devonian Period. Scientists who study the evolution of life during its early days have a difficult job—there is little evidence of the creatures that lived hundreds of millions of years ago. Then there is the problem of how to classify those that are found. Fossils of sea creatures from so long ago bear little resemblance to those that that are alive today, so how to arrange them is unclear. As just one example, some early sea creatures simply floated in the sea while others could clearly swim—but what if it is difficult to distinguish floaters from swimmers? Such difficulties underlie a debate surrounding the Devonian Nekton Revolution—an event theorized to have occurred between 419 and 359 million years ago. Some have suggested that during this period there was a sudden change in the population of creatures living in the sea from floaters to swimmers. So sudden was the change that it has been dubbed a revolution. But that may not have been the case at all—Whalen and Briggs claim that they have found evidence that supports a gradual movement to swimmers. That there was no revolution.The study by the researchers entailed taking a close look at over 2000 fossils from 540 to 252 million years ago and classifying each as either a swimmer or a floater—they also classified them as living either on or near the ocean floor or higher up. The researchers found no evidence of a sudden shift from floaters to swimmers. Instead, they found evidence of a very gradual changeover that happened right up to the end of the Paleozoic.Whalen and Briggs suggest that the reason they came to a different conclusion than earlier teams was because they classified fossils differently. As an example, they point out that they classified some ammonoids as swimmers and some as floaters, whereas prior teams had classified all of them as swimmers. They further argue that logic suggests a gradual shift to swimming. They point out that it is an activity that requires a lot of energy, which means a large intake of oxygen—but during the early parts of the Devonian, there was far less dissolved oxygen in the world’s oceans. Fossils of early tetrapods unearthed in Scotland Citation: New evidence suggests the Devonian Nekton Revolution never occurred (2018, July 18) retrieved 18 August 2019 from https://phys.org/news/2018-07-evidence-devonian-nekton-revolution.html © 2018 Phys.org Explore further Journal information: Proceedings of the Royal Society B More information: The Palaeozoic colonization of the water column and the rise of global nekton, Proceedings of the Royal Society B (2018). rspb.royalsocietypublishing.or … .1098/rspb.2018.0883AbstractThe colonization of the water column is among the most important transformations in the evolution of animal life and global ecosystems. The Devonian nekton revolution has been identified as a major macroevolutionary event signifying the rapid occupation of the water column by independent radiations of swimming animals. Using new data, an expanded taxonomic coverage, sample standardization and increased ecological resolution, we analysed patterns of nektonization during the Palaeozoic. We find that nekton and eunekton were well established prior to the Devonian and did not diversify dramatically during any Palaeozoic interval. Relative nektic diversity and occurrences decreased rather than increased during the Devonian. Eunektic diversity and occurrences increased throughout the Palaeozoic, but this rise was protracted and cannot be attributed to any single interval. Our new data indicate that the metazoan colonization of the water column was considerably more complex and gradual than previously understood. Proportional Palaeozoic water-column generic diversity and occurrences by ecomorphological life mode. Blue denotes plankton, green demersus, yellow nekton. Dashed lines demark Klug et al. DNR results for comparison, P, plankton; D, demersus; N, nekton. (a) SSCG (supplemented Sepkoski’s compendium of Q5 genera) RT diversity. (b) PBDB (Paleobiology Database) SQS standardized SIB diversity. (c) PBDB (Paleobiology Database) generic occurrences. Credit: (c) Proceedings of the Royal Society B (2018). DOI: 10.1098/rspb.2018.0883 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Transmission of green laser light (532 nm) along the low-loss plasmonic waveguide, a) SEM image of a single crystalline flake (top) and fabricated DLSPP waveguide atop of the Ag plate (bottom), b) optical characterization of the waveguide for parallel (top) and perpendicular (bottom) polarizations of 532 nm laser light, c) bright-field microscopy images of the fabricated waveguides of different lengths on the Ag flake (inset shows an image of the grating couplers at the end of the waveguides used to maximize the in-coupling efficiency of DLSPPWs), d) measured propagation length of 11.8 µm for the DLSPPW on the Ag flake at 532 nm. Credit: Light Science & Applications, doi: 10.1038/s41377-018-0062-5. Quantum emitters can be integrated in monolithic nanoscale plasmonic circuitry via low-loss plasmonic configurations to confine light well below the diffraction limit. In integrated quantum plasmonics, waveguides based on surface plasmon polariton (SPP) modes that propagate electromagnetic waves along metal-dielectric or metal-air interfaces are superior to dielectric-based (and therefore diffraction-limited) photonic waveguides. The observation is in respect to the available Purcell enhancement from embedded quantum emitters and the ongoing trend toward on-chip integration and miniaturization to realize optical signal processing and integrated circuits. Different metal-dielectric configurations have been developed for strong light-matter interactions at the scale of the single photon to support the propagation of plasmonic modes confined beyond the diffraction limit. The property can enable unique prospects to design highly integrated photonic-signal processing systems, sensors and optical imaging techniques with nanoscale resolution. Efficiency of the GeV-DLSPPW platform compared with other hybrid quantum systems, a) the dependence of the simulated plasmonic decay rate was observed for the DLSPPW coupled GeV center. The inset showed the cross-section of a y-oriented dipole emitter located within the DLSPPW waveguide, b) distribution profile of the emission efficiency (β-factor) for a distribution inside the GeV center within a nanodiamond, where each colored square represented the central value of the corresponding in-plane dipole position, c) figure of merit (FOM) and transmission length of hybrid quantum plasmonic systems of GeV-DLSPPW on the Ag crystal compared with other quantum emitter plasmonic waveguide (QE PW) hybrid systems. Credit: Light Science & Applications, doi: 10.1038/s41377-018-0062-5. The study was the first to detail the synthesis and characterization of the GeV nanodiamonds. The nanodiamonds were produced using the high-pressure, high-temperature (HPHT) method; Ge was introduced during the growth process to incorporate single GeV centers. The scientists proposed and demonstrated a hybrid approach for nanofabrication using DLSPPW structured on single silver (Ag) crystals that considerably lowered SPP dampening rates, compared to Ag films fabricated by other techniques. The method facilitated sufficiently long SPP propagation at the excitation and emission wavelengths of GeV centers in nanodiamonds incorporated within a plasmonic chip. © 2018 Phys.org The structure of the synthetic GeV nano and microdiamonds were observed in the raw sample using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Synthetic nanodiamonds were spin coated onto Ag-coated silicon wafers and scanned with confocal fluorescence microscopy. Measured data indicated ultrabright, spectrally narrow and stable single photon sources based on single GeV centers in the nanodiamonds, suitable for highly integrated circuits. The polarization characteristics of the GeV nanodiamonds were measured using an analyzer in the detection pathway to determine the projection of single photons emitted on the surface plane. The data measured for a single GeV nanodiamond fit the model polarization characteristics of diamond color centers based on group-IV elements in the periodic table (e.g. silicon-vacancy SiV, germanium-vacancy GeV, and tin-vacancy SnV). More information: On-chip excitation of single germanium vacancies in nanodiamonds embedded in plasmonic waveguides, www.nature.com/articles/s41377-018-0062-5 Siampour et al, 12 Sept 2018, Light Science & Applications.Plasmonics beyond the diffraction limit www.nature.com/articles/nphoton.2009.282 Gramotnev & Bozhevolnyi, 29 Jan 2010, Nature Photonics. Citation: On-chip excitation of nanodiamonds embedded in plasmonic waveguides (2018, October 5) retrieved 18 August 2019 from https://phys.org/news/2018-10-on-chip-nanodiamonds-embedded-plasmonic-waveguides.html Journal information: Light: Science & Applications Additionally, the authors used a single crystalline Ag flake instead of Ag film to significantly enhance the DLSPPW propagation length. Green laser light transmitting through the DLSPPW mode was optically characterized as polarization along the waveguide axis. Transmission was measured for several waveguides of varying lengths to show extraordinary propagation lengths (~11.8 µm) for the green laser light through the low-loss DLSPPW. Using a similar set-up, the scientists proceeded to demonstrate and confirm remote excitation of the GeV center coupled to the DLSPPW mode. Subsequently, the GeV decay rate was simulated using the finite element modeling (FEM) method and a decay rate of up to four-fold was predicted for a GeV center in the waveguide compared to its emission in vacuum. The system demonstrated superior performance when compared with previously demonstrated systems, the observed Purcell factor can be further enhanced in future studies by using a larger refractive index dielectric such as titanium dioxide (TiO2). The study opens the way to integrate an excitation laser, quantum emitter and plasmonic circuit onto the same chip. Previous strategies have demonstrated the detection of single plasmons and two-plasmon interference on a chip. By combining all three technologies on a single chip, the authors envision that it will be possible to integrate all elements of a quantum plasmonic circuit on a chip in the near future. Schematic illustration of the device layout and working principle for on-chip excitation of a nanodiamond. The nanodiamond carries spectrally narrow single GeV quantum emitters embedded in a DLSPP waveguide. Credit: Light Science & Applications, doi: 10.1038/s41377-018-0062-5. A variety of SPP-based structures created in the past include metal nanowires (NW), parallel NWs, V-grooves (VGs) and wedge waveguides that have demonstrated single plasmon guidance for potential quantum applications. The practical realization of such integrated quantum photonics has remained elusive due to several challenges, including high propagation losses of SPP modes and the limited control on single quantum emitters. More recently, studies have nanofabricated low-loss, dielectric-loaded SPP waveguides (DLSPPWs) structured on a silver film for simple quantum plasmonic circuits composed of embedded nanodiamonds with nitrogen-vacancy centers.Now writing in Light Science & Applications, Hamidreza Siampour and co-workers have taken a step forward in the field of integrated quantum plasmonics by demonstrating on-chip coupling between a single photon source and plasmonic waveguide. In the approach, the physicists engineered a nanodiamond featuring a germanium vacancy (GeV) center that emits single photons, embedded inside a plasmonic waveguide composed of dielectric hydrogen silsesquioxane (HSQ) atop a layer of silver fabricated using electron-beam lithography. When a green laser light (532 nm) was coupled to one end of the waveguide via grating couplers to propagate to the nanodiamond, it excited the GeV center, which emitted a single photon that coupled into the plasmon mode of the waveguide. In the work, the researchers achieved long waveguide transmission lengths (33 µm) and efficient coupling (56 percent) to open new avenues in the development of chip-based quantum circuitry. Switchable plasmonic routers controlled by external magnetic fields by using magneto-plasmonic waveguides Explore further On-chip excitation of a single GeV nanodiamond (ND) assigned via controlled placement in a device fabricated with hydrogen silsesquioxane (HSQ) atop Ag film a) the sample layout and working principle of direct excitation of a GeV nanodiamond embedded in a plasmonic waveguide, b) AFM image of the fabricated waveguide (left), CCD image of the whole structure where the nanodiamond is excited (right). The three spots ND, A and B showed excitation and emission of the GeV emitter (ND) as well as coupling of GeV to the DLSPPW mode, propagation and out-coupled radiation from the two ends (A and B). Credit: Light Science & Applications, doi: 10.1038/s41377-018-0062-5. Characterization of the nanodiamonds: a) SEM images of the GeV nano and microdiamonds of the raw sample after HPHT synthesis, the TEM image is seen inset. b) the Ge atom is located in the middle of two empty lattice sites, which includes inversion symmetry, c) the system includes an electronic structure and optical transitions similar to the group IV family of diamond color centers, d) the normalized photon rate for a single GeV nanodiamond in the Ag plane versus the analyzer angle, measured (dot) and model fit (solid). Credit: Light Science & Applications, doi: 10.1038/s41377-018-0062-5. The observed capacity for single-photon emission in diamond nanocrystals can enable hybrid quantum-plasmonic systems that can facilitate remote excitation of the GeV centers incorporated in a plasmonic chip. Siampour et al. elegantly demonstrated the efficient long-range delivery of the GeV-DLSPPW system compared with other hybrid quantum plasmonic systems. An exceptional figure of merit (FOM) of 180 was revealed in the study due to a ~six-fold Purcell enhancement, 56 percent coupling efficiency and ~33 µm transmission length at a wavelength (λ) of 602 nm. Electron beam lithography was used to fabricate the waveguides with HSQ resist on Ag-coated substrates to contain the nanodiamonds featuring single GeV centers – added via controlled placement into the device. The technology provided ~30 nm precision in placement, enhanced via observations with SEM imaging, limited by the size of nanodiamonds, which could be fabricated down to 1 nm using existing diamond synthetic technology. The fabricated waveguide was visualized with atomic force microscopy (AFM) and with a charge coupled device (CCD) camera after nanodiamond excitation via a green pump laser. , Nature Photonics This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Dinosaurs’ rise was ‘more gradual,’ new fossil evidence suggests More information: Rodrigo Temp Müller et al. An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs, Biology Letters (2018). DOI: 10.1098/rsbl.2018.0633 A trio of researchers, two with Universidade Federal de Santa Maria, the other Universidade de São Paulo, have unearthed the remains of three early ancestors of the giant dinosaurs that would later roam the Earth. In their paper published in the journal Biology Letters, Rodrigo Temp Müller, Max Cardoso Langer and Sérgio Dias-da-Silva describe the three complete and very well-preserved dinosaur skeletons they uncovered in a southern part of Brazil. Reconstructed skeleton and representative elements of Macrocollum itaquii. (a) Skull in left lateral view (CAPPA/UFSM 0001a). (b) Skull in dorsal view (CAPPA/UFSM 0001a). (c) Skull in ventral view (CAPPA/UFSM 0001b). (d) Fourth cervical vertebra in left lateral view (CAPPA/UFSM 0001b). (e) Mid-truncal vertebra in left lateral view (CAPPA/UFSM 0001b). (f) Left ilium in lateral view (CAPPA/UFSM 0001b). (g) Left ischium in lateral view (CAPPA/UFSM 0001b). (h) Right pectoral girdle in lateral view (reversed – CAPPA/UFSM 0001b). (i) Right manual digit I in medial view (CAPPA/UFSM 0001b). (j) Right astragalus in dorsal view (CAPPA/UFSM 0001c). (k) Right femur in cranial view (CAPPA/UFSM 0001b). (l) Left pes in cranial view (CAPPA/UFSM 0001a). I-1, phalanx one of the digit I; I-2, phalanx two of the digit I; a, angular; ap, ascending process; co, coracoid; crt, crest; ct, cranial trochanter; d, dentary; dp, diapophysis; epi, epipophysis; f, frontral; fh, femoral head; fob, fossa for the olfactoy bulbus; inf, internarial fenestra; is, ischium shaft; j, jugal; mc, medial condyle; mcI, metacarpal I; mtI, metatarsal I; mtIII, metatarsal III; mtV, metatarsal V; mw, medial wall; mx, maxilla; n, nasal; ns, neural spine; opl, obturador plate; p, parietal; pa, parapophysis; paa, postacetabular ala; pmfo, promaxillary fenestra; pmx, premaxilla; po, postorbital; poz, postzygapophysis; prf, prefrontal; prz, prezygapophysis; q, quadrate; qj, quadratojugal; sa, surangular; sac, supracetabular crest; scp, scapula; sq, squamosal; stf, supratemporal fenestra. Scale bar = 50 mm. (Online version in colour.). Credit: Biology Letters (2018). DOI: 10.1098/rsbl.2018.0633 The skeletal remains have been dated to approximately 225 million years ago, putting them in the Late Triassic, or more specifically, the Norian. The researchers note that they were much smaller than their descendants, standing just five feet tall and weighing approximately 200 pounds—their heads were small enough to be held by a human hand. The remains represent a new species of dinosaur—they have been named Macrocollum itaquii, and are members of a clad made up of other members of the Gondwanan Triassic taxa. They were vegetarian and had very long necks, which allowed them to reach up for higher food sources. They also walked on just two legs. The dinosaurs trod the Earth during the time when Brazil was still a part of the supercontinent Pangaea.Prior research has shown that the most dominant type of vegetation during the Late Triassic was gymnosperms (plants with no flowers that produced seeds and cones) and ferns. A long neck would have allowed the dinosaurs to reach higher than other creatures that lived during the same time period, giving them an obvious advantage.The researchers report that the skeletal remains were found very close together inside five tons of rock and that they were very well preserved. They suggest that the fact that they died together indicates that they likely also lived together, evidence that the early dinosaurs were social creatures. They also suggest that the discovery of M. itaquii skeletal remains will fill in the evolutionary history of dinosaurs in general and sauropodomorphs in particular, perhaps explaining how their descendants grew so large. They note that fossils from early Norian rocks are quite scarce; thus, the find is likely to generate considerable interest in the archaeological community. Journal information: Biology Letters This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2018 Science X Network Citation: Three ancient skeletons, ancestors of giant dinosaurs, unearthed in Brazil (2018, November 21) retrieved 18 August 2019 from https://phys.org/news/2018-11-ancient-skeletons-ancestors-giant-dinosaurs.html Explore further
by NPR News Vanessa Romo 8.26.19 10:31pm The Church of Jesus Christ of Latter-day Saints has prohibited nearly all parishioners from carrying lethal weapons on church property. Prior to the shift in policy, having a weapon on church grounds was considered “inappropriate.” The change was revealed in an update to a handbook sent electronically to local church leaders over the weekend. “Churches are dedicated for the worship of God and as havens from the cares and concerns of the world,” the handbook reads. “With the exception of current law enforcement officers, the carrying of lethal weapons on Church property, concealed or otherwise, is prohibited.”Lethal weapons include a number of possible items including guns.There are have been several gun incidents on church property in recent years. In September, a 74-year-old man accidentally fired a gun in an LDS meetinghouse in Provo, Utah. No one was hurt or injured in the incident. An audio recording later released by MormonLeaks featured an unidentified church leader trying to dissuade others who were present from posting anything on social media.In August 2010, a man fatally shot a Mormon bishop at a chapel in Visalia, Calif., and then was later shot dead by police. Two years earlier, a man shot and killed his pregnant estranged wife in a church parking lot in Lehi, Utah. In an emailed statement, Daniel Woodruff, a spokesman for the church, told NPR the change “took effect the first week of August and will be formally communicated to local Church leaders as new meetinghouse safety guidelines in the near future.”The notice was sent to local leaders in Texas, according to Woodruff, and anticipates an imminent state law that will permit the carrying of open and concealed weapons in places of worship unless a person is notified that it is prohibited.Copyright 2019 NPR. To see more, visit NPR. LDS Church Forbids Lethal Weapons At Church In New Policy… Rick Bowmer
Amidst all the blitzkrieg of new media art and monumental installations, here is a gallery that believes in reinventing and redefining tradition, Gallerie Ganesha is bringing forth a collection of artworks deeply inspired by lineage as well as traditions of tribal and folk art for the India Art Fair.Commenting on the same Shobha Bhatia, director, Gallerie Ganesha said ‘A strong heritage can influence descendants for generations. Tradition, which is always old, is at the same time ever new because it is always reviving. Being born again in each generation. The work of an artist in any era is essentially an amalgamation of his ancestors and predecessors and his own experiences. This year we are showcasing works with a special focus on what lineage influences each artist and how they have chosen to take that inspiration forward. It is an attempt to get the artists to look within and virtually put a spot light on the vocabulary they are using in order to weave their individualistic tales. At the same time, our focus largely is on folk and the tribal tradition.’ Also Read – ‘Playing Jojo was emotionally exhausting’One can see works by the well known tribal artist, Jangarh Singh Shyam, from Madhya Pradesh who died under tragic circumstances in Japan. Artists who are inspired by the folk tradition are Neelkant Choudhary from Madhubani, Bihar, Uma Shankar Shah from Nepal, late Professor K.S.Kulkarni, Dipak Banerjee, Jayasri Burman, Ganga Singh, Laxma Goud and Atul Sinha amongst others.Talking about his works Neelkant Choudhary said, ‘The fine lines of my works have been pulled from the deep and long tradition of the Mithila-Madhubani art form and married to modern metaphors under delicate ministering. I have also brought to the form an entirely new idiom of tone and tenor. Also Read – Leslie doing new comedy special with NetflixAs an artist with a traditional background it was very difficult and also very interesting to break away from the former to latter while also trying to work on the traditional lines so as to maintain the familiarity with the traditional paintings.’Uma Shankar Shah has done etchings and unique prints based on Maithili art, the theme of which is mostly from the Ramayana and prayer wheels from Nepal. He has transformed the traditional art of Maithili Painting into a contemporary extravaganza while meticulously using abstract symbols, motifs, brilliant colours and bold lines characteristic of the traditional art form. Dipak Banerjee’s work is marked by a predominance of patterned structures, calligraphy, anthropomorphic images, Yantras and Mandalas. Over the years he has become more and more rooted in a pictorial mode close to the imagination of Indian miniaturists and folk artisans. KS Kulkarni had developed most simplified constructive forms which have a content dwelling in contemporary psyche. Post modern, unadorned and yet somehow in its heartbeats are engraved into our mind from the tantric concepts of life and going back to primitive cavemen and bushmen.Jayasri Burman’s figures have gained iconic proportions where they no longer remain confined within the space of a mythological or a religious framework, rather they have moved beyond those conventions to establish newer grounds for approaching art.Her work is a reflection of history, myth and ancient texts – an element which transcends time and easy classification in a very immediate and emphatic manner. Atul Sinha’s wood sculptures have a very distinct and prominent overtone of tribal art. The simplicity of form merging beautifully with the ‘complexity’ of narrative to create alluring three dimensional art.Apart from the above, artworks by artists like Alok UNiyal, Avijit Dutta, Badri Narayan, Devdatta Padekar, Maite Delteil, Mohan Singh, Murlidhar Rai, Neeraj Goswami, Niti Jain, Paresh Maity, Sakti Burman, Sangeeta Gupta, Satish Gujral, Sidharth, Vinita Karim, Nayanaa Kanodia, Maya Burman and Ganga Singh.When: 30 JanuaryWhere: NSIC Exhibition Grounds
Nandi prefers to depict Bengali culture such as bauls, kirtan – singing, feminine figures wearing traditional drapery, spiritual elements, use of red as a symbolic element in his works. The works of Nandi are usually based on his surroundings, all his works incorporate an element of sky in them. The artist’s figures are always facing towards light as the artist want to express a simple view that humanity must not lose hope. Commenting on his style of work Nandi says, ‘I begin work only when the subject matter is clear in my mind. Then, I put all my focus and install strict discipline into my work. All other factors, such as human company, music, mobiles and distractions, are excluded.’ Also Read – ‘Playing Jojo was emotionally exhausting’Rajat nandi, is a graduate in visual art from the Indian college of art, Kolkata. The special subjects of Nandi’s paintings are scenic settings of a pastoral idyll. A resident of Kolkata, artist Rajat Nandi first displayed his art work at Rashtrapati Bhawan, New Delhi as a new comer. His art works were so convincing that it grabbed the attention of every artist of different genres.WHEN: On till 14 MarchWHERE: Lokayata: Mulk Raj Anand Center, Hauz Khas Village