Giant Ring Research Articles

Estimation of mechanical expansion stroke and force and effects of processing parameters on expanding quality for giant ring

ABSTRACT Mechanical expansion is the key process in the manufacture of giant metallic ring. The mechanical expansion process of a 10-m-class aluminium alloy ring is taken as the research object in this paper. First, based on the springback theory of small curvature plane bending, the springback ratio formula is derived for the wall thickness centre-line of the ring cross section after unloading, and the mechanical expansion stroke model is established by the mould displacement compensation method. Then, a calculation method for mechanical expansion force is proposed by considering the friction between the mould arc surface and the ring inner wall. Moreover, a finite element model (FEM) is established to simulate the mechanical expansion process of a 10-metre-class aluminium alloy ring using MSC_Marc. The results show that the model proposed in this paper reduces the dimension error of the ring after unloading by 9.19%, and increases the calculation accuracy of the mechanical expansion force by more than 30% under different friction coefficients. Furthermore, the effects of processing parameters, centre angel of the mould segment, relative radius of the mould segment, fillet radius of the edge mould segment, ovality, expansion rate and friction coefficient on the fabricated ring quality are numerically investigated.

Dysphagia

Dysphagia may be oropharyngeal or esophageal. Evaluation is described, including a thorough dysphagia history of associated painful swallowing, location, solids versus liquids, intermittent versus progressive, acute versus gradual onset, and associated symptoms such as weight loss. Physical examination and key diagnostic tests are also reviewed. The evidence-based management of various etiologies of esophageal dysphagia are summarized. Motor disorders described include achalasia, the other primary esophageal motility disorders, and the most common secondary esophageal motility disorders. Esophageal diverticulae are also reviewed in this section. Mechanical esophageal obstruction is presented, including discussions of esophageal webs, rings, peptic stricture, and cancer. Important inflammatory and infectious causes of dysphagia are described, including caustic ingestion, eosinophilic esophagitis, and esophageal infections. The oral phases of liquid and solid swallowing are presented, as are the pharyngeal and esophageal phases of swallowing. Figures show the results of several diagnostic tests and other conditions, including pharyngeoesophageal diverticulum, giant epiphrenic diverticulum, Schatzki ring, and midesophageal squamous cell carcinoma. A flowchart outlines evaluation and management of dysphagia. This review contains 13 figures, 12 tables, and 68 references. Keyword: Esophageal cancer, Achalasia, Diffuse esophageal spasm, Esophageal ring, Peptic esophagitis, Eosinophilic esophagitis, Scleroderma, Esophageal stricture, Chagas disease, Stroke

Dysphagia

Dysphagia may be oropharyngeal or esophageal. Evaluation is described, including a thorough dysphagia history of associated painful swallowing, location, solids versus liquids, intermittent versus progressive, acute versus gradual onset, and associated symptoms such as weight loss. Physical examination and key diagnostic tests are also reviewed. The evidence-based management of various etiologies of esophageal dysphagia are summarized. Motor disorders described include achalasia, the other primary esophageal motility disorders, and the most common secondary esophageal motility disorders. Esophageal diverticulae are also reviewed in this section. Mechanical esophageal obstruction is presented, including discussions of esophageal webs, rings, peptic stricture, and cancer. Important inflammatory and infectious causes of dysphagia are described, including caustic ingestion, eosinophilic esophagitis, and esophageal infections. The oral phases of liquid and solid swallowing are presented, as are the pharyngeal and esophageal phases of swallowing. Figures show the results of several diagnostic tests and other conditions, including pharyngeoesophageal diverticulum, giant epiphrenic diverticulum, Schatzki ring, and midesophageal squamous cell carcinoma. A flowchart outlines evaluation and management of dysphagia. This review contains 13 figures, 12 tables, and 68 references. Keyword: Esophageal cancer, Achalasia, Diffuse esophageal spasm, Esophageal ring, Peptic esophagitis, Eosinophilic esophagitis, Scleroderma, Esophageal stricture, Chagas disease, Stroke

Detection of a repeated transit signature in the light curve of the enigma star KIC 8462852: A possible 928-day period

As revealed by its peculiar Kepler light curve, the enigmatic star KIC 8462852 undergoes short and deep flux dimmings at a priori unrelated epochs. This star presents nonetheless all other characteristics of a quiet 1 Gyr old F3V star. These dimmings resemble the absorption features expected for the transit of dust cometary tails. The exocomet scenario is therefore most commonly advocated. We reanalysed the Kepler data and extracted a new high-quality light curve to allow for the search of shallow signatures of single or a few exocomets. We discovered that among the 22 flux dimming events that we identified, two events present a striking similarity. These events occurred 928.25 days apart and lasted for 4.4 days with a drop in the star brightness by 1000 ppm. We show that the light curve of these events is well explained by the occultation of the star by a giant ring system or by the transit of a string of half a dozen exocomets with a typical dust production rate of 105–106 kg s-1. Assuming that these two similar events are related to the transit of the same object, we derive a period of 928.25 days. The following transit was expected in March 2017 but bad weather prohibited us from detecting it from ground-based spectroscopy. We predict that the next event will occur between 3−8 October 2019.

Giant Ring Mitochondria in a Patient With Heart Failure and Cerebral White Matter Disease Resulting From an MT-TL1 Mitochondrial Gene Mutation

The presence of giant ring mitochondria on endomyocardial biopsy is rarely reported and does not have a well-defined differential diagnosis. We report the case of a 54-year-old man with heart failure and preserved ejection fraction and left ventricular hypertrophy, initially thought to have an infiltrative cardiomyopathy. The patient was found to have extensive vacuolization caused by giant ring mitochondria on endomyocardial biopsy. Mitochondrial genetic testing revealed an A3243G mutation in the MT-TL1 gene, which is a mitochondrial encoded transfer RNA-leucine molecule. Mitochondrial disease should be considered in patients presenting with unexplained cardiomyopathy and skeletal muscle, cerebral, or metabolic abnormalities. In this case, the presence of unexpected extensive cardiomyocyte vacuolization and giant, ring-shaped mitochondria on endomyocardial biopsy prompted mitochondrial genetic testing, which ultimately resulted in the correct diagnosis and treatment.

Lord of the rings.

A giant ring laser, sensitive to the spin of the planet and the twist of earthquakes, will open new windows in earth science.

Constraints on the size and dynamics of the J1407b ring system

Context. J1407 (1SWASP J140747.93-394542.6 in full) is a young star in the Scorpius-Centaurus OB association that underwent a series of complex eclipses over 56 days in 2007. To explain these, it was hypothesised that a secondary substellar companion, J1407b, has a giant ring system filling a large fraction of the Hill sphere, causing the eclipses. Observations have not successfully detected J1407b, but do rule out circular orbits for the companion around the primary star. Aims. We test to what degree the ring model of J1407b could survive in an eccentric orbit required to fit the observations. Methods. We run N-body simulations under the AMUSE framework to test the stability of Hill radius-filling systems where the companion is on an eccentric orbit. Results. We strongly rule out prograde ring systems and find that a secondary of 60 to 100MJup with an 11 year orbital period and retrograde orbiting material can survive for at least $10^4$ orbits and produce eclipses with similar durations as the observed one.

Modeling of a Giant Exoring System Around the Substellar Companion J1407b

AbstractWe model the complex light curve of 1SWASP J140747.93-394542.6, a ~16 Myr old star in the Sco-Cen OB association, with a giant ring system that fills a significant fraction of the Hill sphere of an unseen secondary companion, J1407b. The best ring model has 37 rings and extends out to a radius of 0.6 AU (90 million km), and the rings have an estimated total mass on the order of 1M⊕. The ring system has one clearly defined gap at 0.4 AU (61 million km), which we hypothesize is being cleared out by a < 0.8M⊕exosatellite orbiting around the secondary companion.

MODELING GIANT EXTRASOLAR RING SYSTEMS IN ECLIPSE AND THE CASE OF J1407B: SCULPTING BY EXOMOONS?

The light curve of 1SWASP J140747.93-394542.6, a $\sim$16 Myr old star in the Sco-Cen OB association, underwent a complex series of deep eclipses that lasted 56 days, centered on April 2007. This light curve is interpreted as the transit of a giant ring system that is filling up a fraction of the Hill sphere of an unseen secondary companion, J1407b. We fit the light curve with a model of an azimuthally symmetric ring system, including spatial scales down to the temporal limit set by the star's diameter and relative velocity. The best ring model has 37 rings and extends out to a radius of 0.6 AU (90 million km), and the rings have an estimated total mass on the order of $100 M_{Moon}$. The ring system has one clearly defined gap at 0.4 AU (61 million km), which we hypothesize is being cleared out by a $< 0.8 M_{\oplus}$ exosatellite orbiting around J1407b. This eclipse and model implies that we are seeing a circumplanetary disk undergoing a dynamic transition to an exosatellite-sculpted ring structure and is one of the first seen outside our Solar system.

HMGA2 and MDM2 expression in lipomatous tumors with partial, low-level amplification of sequences from the long arm of chromosome 12

Ordinary lipomas are cytogenetically characterized primarily by simple balanced chromosome aberrations with stable morphologies, most of which affect chromosome segment, 12q13-15, where the HMGA2 gene plays a key pathogenetic role. Atypical lipomatous tumors (ALTs) display supernumerary ring or giant marker chromosomes with amplification of several genes including HMGA2 and MDM2. A study of HMGA2 expression in a variety of adipocytic tumors showed aberrant expression in lipomas with 12q13-15 aberrations and ring chromosomes as well as in ALTs and well-differentiated liposarcomas (WDLSs), and frequent differential expression of HMGA2 exons 1-2 versus that of exons 4-5. A minor subset of adipocytic tumors harbors unbalanced karyotypes with extra copies of 12q sequences in structures that are not giant marker or ring chromosomes. Out of a series of ten such tumors, three lipomas and four ALTs with more than two copies of 12q13-15 and breakpoints in 12q13-15 could be analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) to find out whether HMGA2 and MDM2 expression was more similar to the levels seen in lipomas with cytogenetically balanced aberrations of 12q13-15, or to ALTs with giant ring or marker chromosomes. One of two ALTs with more complex, hyperdiploid karyotypes had expression levels closer to those seen in ALT, whereas the remaining six cases were similar to lipomas with 12q13-15 changes and ring chromosomes. Differential expression was seen in two ALTs and all three lipomas. Two cases showed MDM2 expression levels similar to those found among WDLSs, two cases showed levels similar to those found among lipomas, whereas the remaining three cases displayed intermediate expression levels. The studied cases represent intermediates between lipoma and ALT, insofar as theyshared 12q13-15 rearrangements and karyotypic stability with lipomas and gain of 12q sequences with ALTs. Neither of these characteristics can be used to discriminate between lipoma and ALT.

Giant Ring on the Prairie

Fermilab . Physics, the Frontier, and Megascience. By Lillian Hoddeson, Adrienne W. Kolb, and Catherine Westfall . University of Chicago Press, Chicago, 2008. 513 pp. $45, £31. ISBN 9780226346236. This detailed history illuminates the technical, sociological, and political complexities of establishing and operating a laboratory at the frontier of big physics.

Comment on “Unraveling the Causes of Radiation Belt Enhancements”

The excellent article by M. W. Liemohn and A. A. Chan on the radiation belts (see Eos, 88(42), 16 October 2007) is misleading in its implication that the disturbance storm‐time (Dst) index is an indicator of a magnetospheric ring current. That index is formed from an average of magnetic data from three or four low‐latitude stations that have been fallaciously “adjusted” to a magnetic equatorial location under the 1960's assumption [Sugiura, 1964] that the fields arrive from the growth and decay of a giant ring of current in the magnetosphere. In truth, the index has a negative lognormal form [Campbell, 1996; Yago and Kamide, 2003] as a result of its composition from numerous negative ionospheric and magnetospheric disturbance field sources, each having normal field amplitude distributions [Campbell, 2004]. Some partial ring currents [Lui et al., 1987] and their associated field‐aligned currents, as well as major ionospheric currents flowing from the auroral zone to equatorial latitudes, are the main contributors to the Dst index.

Ring-Expanding Polymerization by Reversible Ring Fusion. A Fascinating Process Driven by Entropy

Grubbs et al. reported a successful method for synthesizing high-molecular weight cyclic polymers without the intermediacy of linear chains (Science 2002, 297, 2041). In spite of its practical significance, there are, however, important questions about this process that remain open. Here it is presented a theory of ring-expanding polymerization mediated by ring-ring equilibria, and driven by entropy only, that addresses the observed results. In particular the theory predicts the existence of a critical concentration (CC) below which only low-molecular weight cyclic oligomers are formed and above which the entire system is predicted to collapse into a single giant ring molecule, the process resembling an irreversible one. Dilution of the system below the CC is predicted to restore the mixture of low-molecular weight cyclic oligomers.

Structure and kinematics of the interstellar medium in the star-forming region in the BCD galaxy VII Zw 403 (UGC 6456)

The structure and kinematics of ionized gas in the star-forming region in the BCD galaxy VIIZw403 (UGC6456) are analyzed using observations with the SCORPIO focal reducer on the 6-m Special Astrophysical Observatory telescope in three modes: direct imaging (in the H-alpha, [OIII], and [SII] lines), long-slit spectroscopy, and spectroscopy with a scanning Fabry-Perot interferometer. In addition to the previously known bright HII regions and the faint giant ring that surrounds the entire star-forming region, many new faint diffuse and arc structures have been detected. Fine structure of the giant ring has been revealed. We do not confirm the previously detected expansion of the bright shells around young stellar associations with a velocity of 50-70 km/s. We have estimated their expansion velocities to be no higher than 15-20 km/s; the corresponding kinematic age, no younger than 3-4 Myr, agrees well with the age of the compact OB associations related to them. We associate the faint extended filamentary and diffuse regions of ionized gas identified in nearly the entire central region of the galaxy and the giant HII ring with the older (10 Myr) stellar population of the most recent starburst. Weak high-velocity [OIII] and H-alpha line wings (up to 300 km/s from the line center) have been detected in the brightest HII region. Such velocities have been observed in the galaxy for the first time. The previously published H-alpha luminosity measurements for the galaxy are refined.

An internal antisense RNA regulates expression of the photosynthesis gene isiA

Small regulatory noncoding RNAs exist in both eukaryotic and prokaryotic organisms. Most of these RNA transcripts are trans-encoded RNAs with short and only partial antisense complementarity to their target RNAs, which regulate gene expression by modifying mRNA stability and translation. In contrast, reports on the function of cis-encoded, perfectly complementary antisense RNAs in eubacteria are rare. Cyanobacteria respond to iron deficiency by expressing IsiA (iron stress-induced protein A), which forms a giant ring structure around photosystem I. Here, we show that this process is controlled by IsrR (iron stress-repressed RNA), a cis-encoded antisense RNA transcribed from the isiA noncoding strand. Artificial overexpression of IsrR under iron stress causes a strongly diminished number of IsiA-photosystem I supercomplexes, whereas IsrR depletion results in premature expression of IsiA. The coupled degradation of IsrR/isiA mRNA duplexes appears to be a reversible switch that can respond to environmental changes. IsrR is the only RNA known so far to regulate a photosynthesis component.

Thermal stability of giant wheel type polyoxomolybdates and their derivatives

The paper compares the thermal behaviour of hydrated giant ring polyoxomolybdates: sodium and ammonium salts as well as sodium polyoxomolybdates containing methanol. Two stages of dehydration are observed: release of water of crystallization reaching its maximum rate at about 70 °C and release of water of constitution above 280 °C leading to a collapse of the ring structure and formation of a new solid phase.

A Neolithic ceremonial timber complex at Ballynahatty, Co. Down

IntroductionBelfast Lough is a deep indent of the Irish Sea into the coastline of Northern Ireland. Its southwestern continuation is the Lagan Valley, which separates the steep scarp ofthe Antrim Plateau (height c. 300 m) from the hills of Co Down (c. 120 m) to the southeast. The River Lagan flows along this broad, undulating valley floor through thick deposits of glacial sands and gravels before emptying into the Lough at Belfast. Eight kilometres southwest of Belfast, the river passes the townland of Ballynahatty, a sandy plateau 100 ha in extent. This was the site in the 4th millenium BC of a small passage tomb, orientated to the northwest (Collins 1954: 48; Lawlor 1918: 16–19). Though now denuded of its covering mound, it provided the subsequent focus for a series of atypical passage tombs utilizing ever smaller settings of stone (Hartwell 1998: 33–6). Shortly after 3000 BC this was followed by a complex of large and elaborate east-facing timber structures (Ballynahatty 5 and 6). These in turn were eventually replaced by the earth and stone hengiform enclosure of the Giant's Ring, built around the original passage tomb.

Interstellar medium surrounding the WO star in the galaxy IC 1613: New optical and radio observations

Observations of the nebula S3 associated with the WO star in the galaxy IC 1613 and of an extended region surrounding S3 are reported. The star and bright core of the nebula were observed with a multipupil fiber spectrograph mounted on the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. Images in the principle spectral lines and integrated spectra of the star and three compact clumps were obtained, and the radial-velocity field constructed. An extended region of the galaxy was observed with the Very Large Array at 21 cm. A giant ring or H I shell enclosing a large fraction of the stellar population in IC 1613 was discovered. The WO star and associated bipolar nebula, which we discovered earlier, lie at the inner edge of the H I ring. A local H I deficiency and two arclike H I ridges were also detected for the first time and probably represent the neutral component of the bipolar shell surrounding the WO star. The two arclike ridges may also have been produced by the collective stellar wind (and supernova explosions?) in OB association No. 9 from the list of Hodge. A scenario for the formation of the extended bipolar feature is discussed, based on the new data.

ChemInform Abstract: Synthesis of over 30‐Membered Giant Ring Compounds: Synthetic Study of Archaeal 36‐ and 72‐Membered Macrocyclic Membrane Lipids

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

From simple building blocks to structures with increasing size and complexity

Abstract In Nature, complex molecular systems like proteins have evolved (natura naturans) which are perfectly suited to their functions. These are produced in a sequence of steps under dissipative conditions—that is, far from equilibrium. The challenge for the chemist is to synthesize correspondingly complex multi-functional molecules also under non-equilibrium (non-dissipative) conditions using multi-component, one-pot reactions, without having to separate and purify each single intermediate product. Relevant model reactions have been discovered in solutions of simple oxoanions of the early transition metals: novel types of molecular growth processes with feedback (including a type of induced cascade) are described leading to different ring-shaped, electron-rich, mixed-valence, giant polyoxomolybdates with nanosized cavities. These can—due to the generation of defects—be covalently linked together to form chains as well as layered mesoporous compounds with properties relevant for materials science. They can also start growing again. The largest polyoxometalate cluster obtained on the basis of this growth process to-date has 248 Mo atoms. Remarkably, such giant ring species can also act as hosts for other clusters forming new types of supramolecular compounds.