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Sample records for dissection daudzslanu spirales

  1. Coronary artery aneurysm and type-A aortic dissection demonstrated by retrospectively ECG-gated multislice spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Fallenberg, Eva Maria; Juergens, Kai Uwe; Fischbach, Roman [Department of Clinical Radiology, University Hospital Muenster (Germany); Wichter, Thomas [Department of Cardiology and Angiology, University Hospital Muenster (Germany); Scheld, Hans H. [Department of Thoracic and Cardiovascular Surgery, University Hospital Muenster (Germany)

    2002-01-01

    The case of a 40-year-old male patient with a coronary aneurysm of the proximal left descending artery (LAD) combined with circumferential type-A dissection of the ascending aorta is reported. Computed tomography angiography of the coronary arteries was performed using multislice spiral computed tomography (MSCT) with retrospective ECG gating. Anatomical relations of the LAD aneurysm as well as the origin of the left coronary artery from the false lumen of the dissection were well depicted for planning of the surgical intervention using this new noninvasive imaging modality. (orig.)

  2. Dissecting the assembly and star formation history of disks and bulges in nearby spirals using the VENGA IFU survey

    Science.gov (United States)

    Carrillo, Andreia Jessica; Jogee, Shardha; Kaplan, Kyle; Weinzirl, Tim; Blanc, Guillermo A.

    2017-06-01

    Integral field spectroscopy of nearby galaxies provides a powerful and unparalleled tool for studying how galaxies assemble the different components -- the bulge, bar, and disk-- that define the Hubble sequence. We explore the assembly and star formation history of these components using galaxies in the VIRUS-P Exploration of Nearby Galaxies (VENGA) survey of 30 nearby spiral galaxies. Compared to other integral field spectroscopy studies of spirals, our study benefits from high spatial sampling and resolution (typically a few 100 pc), large coverage from the bulge to the outer disk, broad wavelength range (3600-6800 A), and medium spectral resolution (120 km/s at 5000 A). In this poster, we present the methodology and data illustrating the exquisite, high-quality, spatially-resolved spectra out to large radii, and the distribution, kinematics, and metallicity of stars and ionized gas. We discuss the next steps in deriving the star formation history (SFH) of bulge, bar, and disk components, and elucidating their assembly pathway by comparing their SFH and structural properties to theoretical models of galaxy evolution. This project is supported by the NSF grants AST-1614798 and AST-1413652.

  3. Aortic non communicating dissections. A study with helical CT; Studio dell'ematoma intramurale aortico. Aspetti con Tomografia Computerizzata spirale

    Energy Technology Data Exchange (ETDEWEB)

    Midiri, M.; Strada, A.; Stabile Ianora, A.A.; Rotondo, A.; Angelelli, G. [Bari Univ., Bari (Italy). Dipt. di Medicina Interna e Medicina Pubblica, Sez. di Diagnostica per Immagini; Scialpi, M. [Ospedale SS. Annunziata, Taranto (Italy); D' Agostino, D.; De Luca Tupputi Schinosa, L. [Bari Univ., Bari (Italy). Dipt. Emergenze Trapianto d' Organo, Sez. di Cardiochirurgia

    2000-09-01

    confused with aortic dissection. The imaging techniques (TEE, CT, MRI) have an important role in the final diagnosis of aortic hematoma. Presently Helical CT and MR angiography are the main tools in the early diagnosis of this condition before the development of complications. In this experience helical CT, before and after the administration of contrast material, was accurate in identifying the hematoma localization and extension. [Italian] Tale studio ha lo scopo di valutare con tecnica TC spirale gli aspetti semeiologici dell'ematoma intramurale dell'aorta e sottolineare il ruolo diagnostico decisivo di tale metodica nello studio di pazienti con quadro clinico acuto sospetto per dissezione aortica. E' stato condotto uno studio retrospettivo (dal 1995 al 1999) sulle immagini di 396 pazienti che avevano eseguito un esame TC in regime d'urgenza per sospetta dissezione aortica. Solo 18 pazienti (6 femmine, 12 maschi) presentavano aspetti tomodensitometrici caratteristici per ematoma intramurale aortico. Gli esami sono stati condotti tutti con TC spirale utilizzando i seguenti parametri: spessore dello strato 10 mm, image index 10, passo della spirale 1,5 mm, algoritmo standard con un minimo di 130 kV e 125 mA. Gli esami sono stati condotti prima e dopo iniezione di 130 ml di mdc in bolo rapido e ricercando i seguenti parametri: sede ed estensione longitudinale dell'ematoma spessore e densita' della parte aortica, presenza e localizzazione delle caclificazioni intimali, regolarita' del lume vero, presenza di emomediastino e/o emotorace. In tutti i 18 pazienti (8 di tipo A e 10 di tipo B) e' stato osservato ispessimento circoscritto parietale tipicamente iperdenso nelle scansioni di base e ipodenso in quelle dopo mdc. In 14/18 pazienti l'ispessimento assumeva disposizione eccentrica, in solo 4/18 era concentrico; in tutti i casi l'ispessimento e' risultato maggiore di 4 mm. In 18/18 pazienti sono state riscontrate

  4. Aortic dissection

    Science.gov (United States)

    Aortic aneurysm - dissecting; Chest pain - aortic dissection; Thoracic aortic aneurysm - dissection ... the chest and abdomen (the descending aorta). Aortic dissection most often happens because of a tear or ...

  5. Spiral symmetry

    CERN Document Server

    Hargittai, Istvan

    1992-01-01

    From the tiny twisted biological molecules to the gargantuan curling arms of many galaxies, the physical world contains a startling repetition of spiral patterns. Today, researchers have a keen interest in identifying, measuring, and defining these patterns in scientific terms. Spirals play an important role in the growth processes of many biological forms and organisms. Also, through time, humans have imitated spiral motifs in their art forms, and invented new and unusual spirals which have no counterparts in the natural world. Therefore, one goal of this multiauthored book is to stress the c

  6. Diagnostic Value of 64-Detector Spiral CT Angiography for Dissecting Aneurysm of Aorta%64层螺旋CT血管造影在主动脉夹层动脉瘤中的应用

    Institute of Scientific and Technical Information of China (English)

    章绪辉; 全显跃; 俞志坚; 黄志平

    2011-01-01

    目的:评价64层螺旋CT血管造影在主动脉夹层动脉瘤中的应用价值。材料与方法:收集主动脉夹层动脉瘤CT血管造影41例,原始横断面图像结合MPR、MIP、VR进行图像分析。结果:原始横断面图像能明确主动脉夹层动脉瘤的诊断,能清晰显示真假腔41例(100%),分离移位的内膜片41例(100%)、内膜破口37例(90.2%)、主动脉分支受累21例(51.2%)、假腔内血栓形成27例(65.9%);MPR、MIP及VR能显示病变的空间情况,对原始横断面图像是很好的补充。对横断面图像较难显示小的内膜破裂口,MPR图像能清楚显示。MIP及VR可以立体、直观地显示主动脉夹层情况。结论:64层螺旋CT血管造影能明确诊断主动脉夹层动脉瘤,具有快速、准确、无创的特点,是诊断主动脉夹层动脉瘤的首选检查方法。%Objective:To evaluate clinical application value of 64-detector spiral CT angiography for dissecting aneurysm of aorta(ADA).Material and methods:CT angiography was performed in 41 cases with ADA,Original axial images combined with MPR,MIP and VR were analyzed.Results:The original axial images can diagnose ADA definitely and clearly show true lumen and false lumen(100%),intimal flap(100%),entry of intimal tear(90.2%),the involvement of branches of aortic(51.2%) and thrombosed false lumen(65.9%),The images of MPR,MIP and VR can show space conditions of aorta and is a very good supplement to the original axial images.The images of MPR can clearly show those entries of intimal tear that the axial images show difficultly,The images of MIP and VR can show the condition of ADA spatially and intuitively.Conclusion:64-detector spiral CT angiography can diagnose ADA definitely and are accurate,quick and non-trauma,so the examination may be as the first choice method in diagnosis of ADA.

  7. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    At the core of Heinz Werner’s concept of development is what he called “the genetic principle of spirality:” over the course of ontogenetic development, lower levels, processes, and functions do not disappear, and can even resurface again under specific conditions, normal and pathological. Werner...

  8. Spiral inflation

    Directory of Open Access Journals (Sweden)

    Gabriela Barenboim

    2015-02-01

    Full Text Available We propose a novel scenario of primordial inflation in which the inflaton goes through a spiral motion starting from around the top of a symmetry breaking potential. We show that, even though inflation takes place for a field value much smaller than Planck scale, it is possible to obtain relatively large tensor-to-scalar ratio (r∼0.1 without fine tuning. The inflationary observables perfectly match Planck data.

  9. Spiralling upward.

    Science.gov (United States)

    Schulgasser, Kalman; Witztum, Allan

    2004-09-21

    Thin vertical leaves often manifest twist. Perhaps the most prominent example of this is in Typha sp., but such twist is also apparent in Narcissus, Pancratium and many other genera. Such a blade is often referred to as a "spiral leaf". We will indicate the mechanical advantage afforded to the leaf by this arrangement, i.e. that it permits the leaf to achieve a greater height without losing stability, that is bending over due to its own weight. We quantify this gain and show how by a simple experiment it can be shown that the advantage is indeed utilized in nature. Typha domingensis is offered as an example.

  10. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    ’s work with Bernard Kaplan on symbol formation is a primer on this idea. This paper examines the idea of spirality and develops the notion of dynamic coexistence that can clarify the issue of directionality of development; that is, what is the general trajectory or ground plan that development assumes....... Directionality is discussed in terms of the organism-in-environment unfolding over time as the unit of developmental analysis. Thinking on this issue has proceeded from the nature–nurture debates, to recognition of the interaction of external and internal processes, to transactions between the organism...

  11. Quantum spirals

    CERN Document Server

    Yoshida, Z

    2016-01-01

    Quantum systems often exhibit fundamental incapability to entertain vortex. The Meissner effect, a complete expulsion of the magnetic field (the electromagnetic vorticity), for instance, is taken to be the defining attribute of the superconducting state. Superfluidity is another, close-parallel example; fluid vorticity can reside only on topological defects with a limited (quantized) amount. Recent developments in the Bose-Einstein condensates produced by particle traps further emphasize this characteristic. We show that the challenge of imparting vorticity to a quantum fluid can be met through a nonlinear mechanism operating in a hot fluid corresponding to a thermally modified Pauli-Schroedinger spinor field. In a simple field-free model, we show that the thermal effect, represented by a nonlinear, non-Hermitian Hamiltonian, in conjunction with spin vorticity, leads to new interesting quantum states; a spiral solution is explicitly worked out.

  12. Spiral tectonics

    Science.gov (United States)

    Hassan Asadiyan, Mohammad

    2014-05-01

    Spiral Tectonics (ST) is a new window to global tectonics introduced as alternative model for Plate Tectonics (PT). ST based upon Dahw(rolling) and Tahw(spreading) dynamics. Analogues to electric and magnetic components in the electromagnetic theory we could consider Dahw and Tahw as components of geodynamics, when one component increases the other decreases and vice versa. They are changed to each other during geological history. D-component represents continental crust and T-component represents oceanic crust. D and T are two arm of spiral-cell. T-arm 180 degree lags behind D-arm so named Retard-arm with respect to D or Forward-arm. It seems primary cell injected several billions years ago from Earth's center therefore the Earth's core was built up first then mantel and finally the crust was build up. Crust building initiate from Arabia (Mecca). As the universe extended gravitation wave swirled the earth fractaly along cycloid path from big to small scale. In global scale (order-0) ST collect continents in one side and abandoned Pacific Ocean in the other side. Recent researches also show two mantels upwelling in opposite side of the Earth: one under Africa (tectonic pose) and the other under Pacific Ocean (tectonic tail). In higher order (order-1) ST build up Africa in one side and S.America in the other side therefore left Atlantic Ocean meandered in between. In order-n e.g. Khoor Musa and Bandar-Deylam bay are seen meandered easterly in the Iranian part but Khoor Abdullah and Kuwait bay meandered westerly in the Arabian part, they are distributed symmetrically with respect to axis of Persian Gulf(PG), these two are fractal components of easterly Caspian-wing and westerly Black Sea-wing which split up from Anatoly. Caspian Sea and Black Sea make two legs of Y-like structure, this shape completely fitted with GPS-velocity map which start from PG and split up in the Catastrophic Point(Anatoly). We could consider PG as remnants of Ancient Ocean which spent up

  13. Neck dissection - discharge

    Science.gov (United States)

    Radical neck dissection - discharge; Modified radical neck dissection - discharge; Selective neck dissection - discharge ... 659-665. Robbins KT, Samant S, Ronen O. Neck dissection. In: Flint PW, Haughey BH, Lund V, et ...

  14. Nuclear spirals in galaxies

    OpenAIRE

    Maciejewski, Witold

    2006-01-01

    Recent high-resolution observations indicate that nuclear spirals are often present in the innermost few hundred parsecs of disc galaxies. My models show that nuclear spirals form naturally as a gas response to non-axisymmetry in the gravitational potential. Some nuclear spirals take the form of spiral shocks, resulting in streaming motions in the gas, and in inflow comparable to the accretion rates needed to power local Active Galactic Nuclei. Recently streaming motions of amplitude expected...

  15. Cochlea and other spiral forms in nature and art.

    Science.gov (United States)

    Marinković, Slobodan; Stanković, Predrag; Štrbac, Mile; Tomić, Irina; Ćetković, Mila

    2012-01-01

    The original appearance of the cochlea and the specific shape of a spiral are interesting for both the scientists and artists. Yet, a correlation between the cochlea and the spiral forms in nature and art has been very rarely mentioned. The aim of this study was to investigate the possible correlation between the cochlea and the other spiral objects in nature, as well as the artistic presentation of the spiral forms. We explored data related to many natural objects and examined 13,625 artworks created by 2049 artists. We also dissected 2 human cochleas and prepared histologic slices of a rat cochlea. The cochlea is a spiral, cone-shaped osseous structure that resembles certain other spiral forms in nature. It was noticed that parts of some plants are arranged in a spiral manner, often according to Fibonacci numbers. Certain animals, their parts, or their products also represent various types of spirals. Many of them, including the cochlea, belong to the logarithmic type. Nature created spiral forms in the living world to pack a larger number of structures in a limited space and also to improve their function. Because the cochlea and other spiral forms have a certain aesthetic value, many artists presented them in their works of art. There is a mathematical and geometric correlation between the cochlea and natural spiral objects, and the same functional reason for their formation. The artists' imagery added a new aspect to those domains. Obviously, the creativity of nature and Homo sapiens has no limits--like the infinite distal part of the spiral. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Electromechanics of graphene spirals

    Directory of Open Access Journals (Sweden)

    Topi Korhonen

    2014-12-01

    Full Text Available Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  17. Electromechanics of graphene spirals

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, Topi; Koskinen, Pekka, E-mail: pekka.koskinen@iki.fi [NanoScience Center, Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland)

    2014-12-15

    Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  18. Spherical long spirals

    Science.gov (United States)

    Georgiev, G. H.; Dinkova, C. L.

    2013-10-01

    Long spirals in the Euclidean plane have been introduced by A. Kurnosenko five years ago. Using a natural map of the shape sphere into the extended Gaussian plane we study spherical curves that are pre-images of plane long spirals. Loxodromes and spherical spiral antennas are typical examples of such spherical long spirals. The set of all planar spirals leaves invariant under an arbitrary similarity transformation. This set is divided in two disjoint classes by A. Kirnosenko. The first class is consist of the so-called short spirals which are widely used in geometric modeling. The second class of planar long spirals contains well-known logarithmic spiral and Archimedean spirals which have many applications in mathematics, astrophysics and industry. The notion of simplicial shape space is due to D. Kendall. The most popular simplicial shape space of order (2,3) is the set of equivalence classes of similar triangles in the plane. The sphere of radius 1/2 centered at the origin can be considered as a model of this quotient space, so-called the shape sphere. F. Bookstein and J. Lester showed that the one-point extension of the Euclidean plane, so-called the extended Gaussian plane, is another model of the same simplicial shape space. The present paper gives a description of long spirals on the shape sphere by the use a natural conformal mapping between two models. First, we examine long spirals in the extended Gaussian plane. After that, we describe some differential geometric properties of the shape sphere. Finally, we discuss parameterizations of long spirals on the shape sphere.

  19. Genesis of spiral galaxies

    CERN Document Server

    Kiselev, Valery V

    2013-01-01

    Enigmatic spiral structure of many galaxies and its huge orbital momentum originated due to the capture of lightweight bare black hole by gravity of heavy primordial gas cloud at large impact parameter. The rotating of black hole caused the formation of accretion disc from the cloud and the transfer of orbital momentum to the disc, while during the fall to the center of mass, the spiral trace of black hole in the disc did create the spiral front line of sound waves in the gas, that further evolved into the stellar spiral arms. This mechanism opens the way to study features of spiral galaxy formation, say, an influence and a significance of dark matter in this process.

  20. Aortic dissection (image)

    Science.gov (United States)

    Aortic dissection is a condition in which there is bleeding into and along the wall of the aorta (the ... the inner wall of the artery. Although aortic dissection can affect anybody, it is most often seen ...

  1. Carotid dissection (image)

    Science.gov (United States)

    ... This leaking of blood into the artery wall (dissection) may cause a clot to form, reducing blood ... the neck, which means stroke secondary to carotid dissection may occur in young people as well as ...

  2. Superluminous Spiral Galaxies

    CERN Document Server

    Ogle, Patrick M; Nader, Cyril; Helou, George

    2015-01-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L_r=8-14L* (4.3-7.5E44 erg/s). These super spiral galaxies are also giant and massive, with diameter D=57-134 kpc and stellar mass M_stars=0.3-3.4E11 M_sun. We find 53 super spirals out of a complete sample of 1,616 SDSS galaxies with redshift z8L*. The closest example is found at z=0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and WISE colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5-65 M_sun/yr place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers--a possible clue to their formation. We su...

  3. Spiral Countercurrent Chromatography

    Science.gov (United States)

    Ito, Yoichiro; Knight, Martha; Finn, Thomas M.

    2013-01-01

    For many years, high-speed countercurrent chromatography conducted in open tubing coils has been widely used for the separation of natural and synthetic compounds. In this method, the retention of the stationary phase is solely provided by the Archimedean screw effect by rotating the coiled column in the centrifugal force field. However, the system fails to retain enough of the stationary phase for polar solvent systems such as the aqueous–aqueous polymer phase systems. To address this problem, the geometry of the coiled channel was modified to a spiral configuration so that the system could utilize the radially acting centrifugal force. This successfully improved the retention of the stationary phase. Two different types of spiral columns were fabricated: the spiral disk assembly, made by stacking multiple plastic disks with single or four interwoven spiral channels connected in series, and the spiral tube assembly, made by inserting the tetrafluoroethylene tubing into a spiral frame (spiral tube support). The capabilities of these column assemblies were successfully demonstrated by separations of peptides and proteins with polar two-phase solvent systems whose stationary phases had not been well retained in the earlier multilayer coil separation column for high-speed countercurrent chromatography. PMID:23833207

  4. The Spiral of Euroscepticism

    DEFF Research Database (Denmark)

    Galpin, Charlotte; Trenz, Hans-Jörg

    2017-01-01

    of Euroscepticism’, taking media autonomy seriously to understand how media logics and selective devices contribute to the shaping of public discourse about the EU. We review the literature on the media and EU legitimacy to show how media frames and their amplification on social media can account for the salience......Media scholars have increasingly examined the effects of a negativity bias that applies to political news. In the ‘spiral of cynicism’, journalist preferences for negative news correspond to public demands for sensational news. We argue that this spiral of cynicism in EU news results in a ‘spiral...

  5. Galaxy Zoo: Passive Red Spirals

    CERN Document Server

    Masters, Karen L; Romer, A Kathy; Nichol, Robert C; Bamford, Steven P; Schawinski, Kevin; Lintott, Chris J; Andreescu, Dan; Campbell, Heather C; Crowcroft, Ben; Doyle, Isabelle; Edmondson, Edward M; Murray, Phil; Raddick, M Jordan; Slosar, Anze; Szalay, Alexander S; Vandenberg, Jan

    2009-01-01

    We study the spectroscopic properties and environments of red spiral galaxies found by the Galaxy Zoo project. By carefully selecting face-on, disk dominated spirals we construct a sample of truly passive disks (not dust reddened, nor dominated by old stellar populations in a bulge). As such, our red spirals represent an interesting set of possible transition objects between normal blue spirals and red early types. We use SDSS data to investigate the physical processes which could have turned these objects red without disturbing their morphology. Red spirals prefer intermediate density regimes, however there are no obvious correlations between red spiral properties and environment - environment alone is not sufficient to determine if a galaxy will become a red spiral. Red spirals are a small fraction of spirals at low masses, but dominate at large stellar masses - massive galaxies are red independent of morphology. We confirm that red spirals have older stellar populations and less recent star formation than ...

  6. SUPERLUMINOUS SPIRAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Ogle, Patrick M.; Lanz, Lauranne; Nader, Cyril; Helou, George, E-mail: ogle@ipac.caltech.edu [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States)

    2016-02-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L{sub r} = 8–14L* (4.3–7.5 × 10{sup 44} erg s{sup −1}). These super spiral galaxies are also giant and massive, with diameter D = 57–134 kpc and stellar mass M{sub stars} = 0.3–3.4 × 10{sup 11}M{sub ⊙}. We find 53 super spirals out of a complete sample of 1616 SDSS galaxies with redshift z < 0.3 and L{sub r} > 8L*. The closest example is found at z = 0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and Wide-field Infrared Survey Explorer colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5–65 M{sub ⊙} yr{sup −1} place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers—a possible clue to their formation. We suggest that super spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become massive lenticular galaxies after they are cut off from their gas supply and their disks fade.

  7. Spiral 2 Week

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The main goal of this meeting is to present and discuss the current status of the Spiral-2 project at GANIL in front of a large community of scientists and engineers. Different issues have been tackled particularly the equipment around Spiral-2 like injectors, cryo-modules or beam diagnostics, a workshop was devoted to other facilities dedicated to radioactive ion beam production. This document gathers only the slides of the presentations.

  8. Spiral Shell Collection

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    In 1988 Zheng Haigen, a seaman with the Towboat Company of the Shanghai Salvage Bureau, began collecting spiral shells. Today he has more than 600 in his collection. The most valuable are the rare parrot shell and a shell whose spirals wind counter-clockwise. In 1991 a miniature conch with a diameter of 0.31 millimeters that he found buried in tons of sand made the Guinness Book of World Records.

  9. study on the significance of application of multi - slice spiral CT(MsCT)angiography in diagnosis of aortic dissecting aneurysm%多层螺旋 CT 血管成像技术在主动脉夹层动脉瘤中的应用价值

    Institute of Scientific and Technical Information of China (English)

    张喜军; 李淳成; 吴耀军

    2015-01-01

    供立体及精确的解剖信息,故 MSCTA 可作为 AD 首选的影像学检查方法。%Objectine To explore the diagnostic performance and clinical significance of multi - slice spiral CT(MSCT)angiography and computed tomography angiography(CTA)in diagnosis of aortic dissecting aneurysm. Methods The Clinical data of 68 cases diagnosed with aor-tic dissections(AD)were retrospectively analyzed. All these patients were examined with 64 - detector CTA using intelligent tracking technique for rapid volume enhanced scanning,and primary data were processed with multiplannar reformation( MPR),curved plannar reconstruction (CRP),the maximum intensity projection(MIP),volume representation technical reconstruction(VR),CT virtual endoscopy(CTVE)and vol-ume representative technical reconstruction(VR). The true and false lumens,intimal flap and tears were analyzed. Results There were 21 cases with Stanford A type,and 47 cases with B type;the average strengthening value of AD in true lumen group(279. 00 ± 46. 55 HU)was significant-ly higher than the average strengthening value of false lumen group(260. 06 ± 49. 59 HU,t = 2. 2963,P = 2. 2963). It could be seen in 66 ca-ses(97. 06% )of first tear and 60 cases(88. 24% )of re - entry tears. In 42 cases of true lumen value which strengthening value was greater than that of false lumen,the first tear size was 12. 05 ± 6. 48 mm,which was much smaller than the size of first tear(19. 08 ± 8. 56 mm,t = 3. 8394, P = 3. 8394)in 26 cases with true lumen,in which strengthening value was almost the same to that of false lumen. The true and false lumens of 60 patients with AD were spirally contorted,another 8 cases were parallel contortion,their size was differed. Enhanced scanning of 68 patients showed mezzanine intimal flap was clearly performed,and the movement was in accordance with that of true and false lumens. Bilateral common il-iac arteries were most easily affected. The rates of breach in MPR,CPR,CTVE and VR were 92. 65% ,95

  10. Spirality: A Noval Way to Measure Spiral Arm Pitch Angle

    Science.gov (United States)

    Shields, Douglas; Arkansas Galaxy Evolution Survey

    2017-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 minutes per galaxy, assuming 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code’s results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality’s error bars overlapped 2DFFT’s error bars for 26 of the 30 galaxies. The two methods’ agreement correlates strongly with galaxy radius in pixels and also with i-band magnitude, but not with redshift, a result that is consistent with at least some galaxies’ spiral structure being fully formed by z=1.2, beyond which there are few galaxies in our sample. We also analyze apparent spiral structure of three galaxies beyond z=2. The Spirality code package also includes GenSpiral, which produces FITS images of synthetic spirals, and SpiralArmCount, which uses a one-dimensional Fast Fourier Transform to count the spiral arms of a galaxy after its pitch is determined.

  11. Investigating Dwarf Spiral Galaxies

    Science.gov (United States)

    Weerasooriya, Sachithra; Dunn, Jacqueline M.

    2017-01-01

    Several studies have proposed that dwarf elliptical / spheroidal galaxies form through the transformation of dwarf irregular galaxies. Early and late type dwarfs resemble each other in terms of their observed colors and light distributions (each can often be represented by exponential disks), providing reason to propose an evolutionary link between the two types. The existence of dwarf spirals has been largely debated. However, more and more recent studies are using the designation of dwarf spiral to describe their targets of interest. This project seeks to explore where dwarf spirals fit into the above mentioned evolutionary sequence, if at all. Optical colors will be compared between a sample of dwarf irregular, dwarf elliptical, and dwarf spiral galaxies. The dwarf irregular and dwarf elliptical samples have previously been found to overlap in both optical color and surface brightness profile shape when limiting the samples to their fainter members. A preliminary comparison including the dwarf spiral sample will be presented here, along with a comparison of available ultraviolet and near-infrared data. Initial results indicate a potential evolutionary link that merits further investigation.

  12. Embracing the Spiral

    Directory of Open Access Journals (Sweden)

    Li Mao

    2016-12-01

    Full Text Available Critical research demands that we interrogate our own positionality and social location. Critical reflexivity is a form of researcher critical consciousness that is constant and dynamic in a complex spiral-like process starting within our own experiences as racialized, gendered, and classed beings embedded in particular sociopolitical contexts. Across diverse critical methodologies, a group of graduate students and their supervisor explored their own conceptualization of the reflexivity spiral by reflecting on how their research motivations and methodologies emerged from their racializing, colonizing, language-learning, parenting, and identity negotiating experiences. In this article, they present a spiral model of the critical reflexivity process, review the literature on reflexivity, and conclude with a description of critical reflexivity as a social practice within a supportive and collaborative graduate school experience.

  13. Plasmonic response of nanoscale spirals.

    Science.gov (United States)

    Ziegler, Jed I; Haglund, Richard F

    2010-08-11

    The Archimedean spiral geometry presents a platform for exploration of complex plasmonic mechanisms and applications. Here we show both through simulations and experiment that more complex plasmonic modes with unique near-field structure and larger mode volumes can be realized within a single, topologically robust structure. In the spiral, complex polarization response, resonant interactions and symmetry-breaking features are defined by the width and spacing of the spiral tracks and by the winding number of the spiral.

  14. Galactic Spiral Structure

    CERN Document Server

    Francis, Charles

    2009-01-01

    We describe the structure and composition of six major stellar streams in a population of 20 574 local stars in the New Hipparcos Reduction with known radial velocities. We find that, once fast moving stars are excluded, almost all stars belong to one of these streams. The results of our investigation have lead us to re-examine the hydrogen maps of the Milky Way, from which we identify the possibility of a symmetric two-armed spiral with half the conventionally accepted pitch angle. We describe a model of spiral arm motions which matches the observed velocities and composition of the six major streams, as well as the observed velocities of the Hyades and Praesepe clusters at the extreme of the Hyades stream. Stellar orbits are perturbed ellipses aligned at a focus in coordinates rotating at the rate of precession of pericentre. Stars join a spiral arm just before apocentre, follow the arm for more than half an orbit, and leave the arm soon after pericentre. Spiral pattern speed equals the mean rate of precess...

  15. Ferroelectricity in spiral magnets

    NARCIS (Netherlands)

    Mostovoy, M

    2006-01-01

    It was recently observed that the ferroelectrics showing the strongest sensitivity to an applied magnetic field are spiral magnets. We present a phenomenological theory of inhomogeneous ferroelectric magnets, which describes their thermodynamics and magnetic field behavior, e.g., dielectric suscepti

  16. Noise reduction of spiral ducts.

    Science.gov (United States)

    Lapka, Wojciech; Cempel, Czesław

    2007-01-01

    The paper presents noise reduction (NR) of spiral ducts as a result of computational modeling of acoustic wave propagation. Three-dimensional models were created with the finite element method in COMSOL Multiphysics version 3.3. Nine models of spiral ducts with 1-9 spiral leads were considered. Time-harmonic analysis was used to predict NR, which was shown in spectral and interval frequency bands. Spiral duct performance can be seen as a comparison of NR before and after a change from a circular to a spiral duct.

  17. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov...

  18. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads;

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov...

  19. Mastectomy using ultrasonic dissection

    DEFF Research Database (Denmark)

    Galatius, Hanne; Okholm, Mette; Hoffmann, Jack

    2003-01-01

    Seroma formation is the most common complication after mastectomy. Among the several known etiological factors the surgical procedure used may be of importance for seroma formation. This prospective study was carried out to evaluate the ultrasonic energy dissection technique and its effect...... on seroma formation and other complications: 59 patients with operable breast cancer underwent modified radical mastectomy, performed in 30 of them with an Ultracision Harmonic scalpel and in 29 with scissors and electrocautery. In all cases a standard level II axillary dissection was performed...... groups. In conclusion, neither clinical advantages or disadvantages of the ultrasound dissection technique were found....

  20. Forming Spirals From Shadows

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    What causes the large-scale spiral structures found in some protoplanetary disks? Most models assume theyre created by newly-forming planets, but a new study suggests that planets might have nothing to do with it.Perturbations from Planets?In some transition disks protoplanetary disks with gaps in their inner regions weve directly imaged large-scale spiral arms. Many theories currently attribute the formation of these structures to young planets: either the direct perturbations of a planet embedded in the disk cause the spirals, or theyre indirectly caused by the orbit of a planetary body outside of the arms.Another example of spiral arms detected in a protoplanetary disk, MWC 758. [NASA/ESA/ESO/M. Benisty et al.]But what if you could get spirals without any planets? A team of scientists led by Matas Montesinos (University of Chile) have recently published a study in which they examine what happens to a shadowed protoplanetary disk.Casting Shadows with WarpsIn the teams setup, they envision a protoplanetary disk that is warped: the inner region is slightly tilted relative to the outer region. As the central star casts light out over its protoplanetary disk, this disk warping would cause some regions of the disk to be shaded in a way that isnt axially symmetric with potentially interesting implications.Montesinos and collaborators ran 2D hydrodynamics simulations to determine what happens to the motion of particles within the disk when they pass in and out of the shadowed regions. Since the shadowed regions are significantly colder than the illuminated disk, the pressure in these regions is much lower. Particles are therefore accelerated and decelerated as they pass through these regions, and the lack of axial symmetry causes spiral density waves to form in the disk as a result.Initial profile for the stellar heating rate per unit area for one of the authors simulations. The regions shadowed as a result of the disk warp subtend 0.5 radians each (shown on the left

  1. Spiral 2 workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop.

  2. Is dissection humane?

    OpenAIRE

    Hasan, Tabinda

    2011-01-01

    Dissection is being jeopardized in the modern medical education. It has unrelentingly faced the lashes of time and has been the scapegoat for numerous convenient curricula reforms and subjective biases. The cadaver is unparallel in establishing core knowledge among the medical community and it needs to be appreciated in a new light in the “cyber anatomy” realm of today. This article elucidates the medical and ethical validity of continuing human body dissection in medicine which outweighs all...

  3. Spiral multicapillary columns

    Science.gov (United States)

    Efimenko, A. P.; Naumenko, I. I.; Soboleva, V. K.

    2008-08-01

    It was shown in a theoretical study and confirmed by experiment that a spiral multicapillary column had maximum efficiency if the bunch of capillaries was additionally coiled around its longitudinal axis to produce an integral number of coils. This technique made it possible to manufacture gas-chromatographic columns with performance as high as 12 to 16 thousand theoretical plates. These columns can find various applications, especially if quick separation is required.

  4. Hinged Dissections Exist

    CERN Document Server

    Abbott, Timothy G; Charlton, David; Demaine, Erik D; Demaine, Martin L; Kominers, Scott D

    2007-01-01

    We prove that any finite collection of polygons of equal area has a common hinged dissection. That is, for any such collection of polygons there exists a chain of polygons hinged at vertices that can be folded in the plane continuously without self-intersection to form any polygon in the collection. This result settles the open problem about the existence of hinged dissections between pairs of polygons that goes back implicitly to 1864 and has been studied extensively in the past ten years. Our result generalizes and indeed builds upon the result from 1814 that polygons have common dissections (without hinges). We also extend our common dissection result to edge-hinged dissections of solid 3D polyhedra that have a common (unhinged) dissection, as determined by Dehn's 1900 solution to Hilbert's Third Problem. Our proofs are constructive, giving explicit algorithms in all cases. For a constant number of planar polygons, both the number of pieces and running time required by our construction are pseudopolynomial...

  5. Interweaving Chiral Spirals

    CERN Document Server

    Kojo, Toru; Fukushima, Kenji; McLerran, Larry; Pisarski, Robert D

    2011-01-01

    We elaborate how to construct the interweaving chiral spirals in (2+1) dimensions, that is defined as a superposition of differently oriented chiral spirals. We divide the two-dimensional Fermi sea into distinct wedges characterized by the opening angle 2 Theta and the depth Q \\simeq pF, where pF is the Fermi momentum. Each wedge earns an energy gain by forming a single chiral spiral. The optimal values for Theta and Q are chosen by the balance between this energy gain and the energy costs from the deformed Fermi surface (dominant at large Theta) and patch-patch interactions (dominant at small Theta). We estimate these energy gains and costs by means of the expansions in terms of 1/Nc, Lambda_QCD/Q, and Theta using a non-local four-Fermi interaction model: At small 1/Nc the mass gap (chiral condensate) is large enough and the interaction among quarks and the condensate is local in momentum space thanks to the form factor in our non-local model. The fact that patch-patch interactions lie only near the patch bo...

  6. Satellites of spiral galaxies

    Science.gov (United States)

    Zaritsky, Dennis; Smith, Rodney; Frenk, Carlos; White, Simon D. M.

    1993-01-01

    We present a survey of satellites around a homogeneous set of late-type spirals with luminosity similar to that of the Milky Way. On average, we find fewer than 1.5 satellites per primary, but we argue that we can treat the survey as an ensemble and so derive the properties of the halo of a 'typical' isolated spiral. The projected density profile of the ensemble falls off approximately as 1/r. Within 50 kpc the azimuthal distribution of satellites shows some evidence for the 'Holmberg effect', an excess near the minor axis of the primary; however, at larger projected distances, the distribution appears isotropic. There is a weak but significant correlation between the size of a satellite and its distance from its primary, as expected if satellites are tidally truncated. Neither Hubble type nor spectral characteristics correlate with apparent separation. The ensemble of satellites appears to be rotating at about 30 km/s in the same direction as the galactic disk. Satellites on prograde orbits tend to be brighter than those on retrograde orbits. The typical velocity difference between a satellite and its primary shows no clear dependence either on apparent separation, or on the rotation speed of the primary. Thus our survey demonstrates that isolated spiral galaxies have massive halos that extend to many optical radii.

  7. Spirality: A Noval Way to Measure Spiral Arm Pitch Angle

    Science.gov (United States)

    Shields, Douglas W.; Boe, Benjamin; Henderson, Casey L.; Hartley, Matthew; Davis, Benjamin L.; Pour Imani, Hamed; Kennefick, Daniel; Kennefick, Julia D.

    2015-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. For a given pitch angle template, the mean pixel value is found along each of typically 1000 spiral axes. The fitting function, which shows a local maximum at the best-fit pitch angle, is the variance of these means. Error bars are found by varying the inner radius of the measurement annulus and finding the standard deviation of the best-fit pitches. Computation time is typically on the order of 2 minutes per galaxy, assuming at least 8 GB of working memory. We tested the code using 128 synthetic spiral images of known pitch. These spirals varied in the number of spiral arms, pitch angle, degree of logarithmicity, radius, SNR, inclination angle, bar length, and bulge radius. A correct result is defined as a result that matches the true pitch within the error bars, with error bars no greater than ±7°. For the non-logarithmic spiral sample, the correct answer is similarly defined, with the mean pitch as function of radius in place of the true pitch. For all synthetic spirals, correct results were obtained so long as SNR > 0.25, the bar length was no more than 60% of the spiral's diameter (when the bar was included in the measurement), the input center of the spiral was no more than 6% of the spiral radius away from the true center, and the inclination angle was no more than 30°. The synthetic spirals were not deprojected prior to measurement. The code produced the correct result for all barred spirals when the measurement annulus was placed outside the bar. Additionally, we compared the code's results against 2DFFT results for 203 visually selected spiral galaxies in GOODS North and South. Among the entire sample, Spirality's error bars overlapped 2DFFT's error bars 64% of the time. For those galaxies in which Source code is available by email request from the primary author.

  8. Spirality: A Novel Way to Measure Spiral Arm Pitch Angle

    CERN Document Server

    Shields, Douglas W; Pfountz, Casey; Davis, Benjamin L; Hartley, Matthew; Imani, Hamed Pour; Slade, Zac; Kennefick, Daniel; Kennefick, Julia

    2015-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 minutes per galaxy, assuming at least 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code's results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality's error bars overlapped 2DFFT's error bars for 26 of the 30 galaxies. The two methods' agreement correlates strongly with galaxy radius in pixels and also with i-band magnitude, but not with redshift, a result that is consistent with at least some galaxies' spiral structure being fully formed by z=1.2, beyond which there are few galaxies in our sample. The Spirality code pa...

  9. Intermittency in spiral Poiseuille flow

    Energy Technology Data Exchange (ETDEWEB)

    Heise, M; Abshagen, J; Menck, A; Pflster, G [Institute of Experimental and Applied Physics, University of Kiel, 24098 Kiel (Germany)

    2005-01-01

    The results of an experimental study on intermittent spiral vortices observed in a counter-rotating Taylor-Couette system with an additional axial through flow, i.e. Spiral-Poiseuille flow, are presented. Convectively unstable upstream propagating spiral vortices appear in the laminar basic flow from an oscillatory instability and in general become absolutely unstable at higher inner cylinder Reynolds number. It is found that at Reynolds numbers above the absolute stability border the spiral vortices become unstable and a complex flow state showing intermittent bursts appears. The intermittent flow state is characterised by an irregular alternation between clearly distinguishable 'laminar' phases corresponding to up-and downstream propagating spiral vortices as well as propagating Taylor vortices. For a sufficiently high rate of axial through flow it is found that intermittency can occur directly from the convectively unstable regime of the upstream propagating spiral vortices.

  10. Star Formation in Spiral Arms

    CERN Document Server

    Elmegreen, Bruce G

    2011-01-01

    The origin and types of spiral arms are reviewed with an emphasis on the connections between these arms and star formation. Flocculent spiral arms are most likely the result of transient instabilities in the gas that promote dense cloud formation, star formation, and generate turbulence. Long irregular spiral arms are usually initiated by gravitational instabilities in the stars, with the gas contributing to and following these instabilities, and star formation in the gas. Global spiral arms triggered by global perturbations, such as a galaxy interaction, can be wavemodes with wave reflection in the inner regions. They might grow and dominate the disk for several rotations before degenerating into higher-order modes by non-linear effects. Interstellar gas flows through these global arms, and through the more transient stellar spiral arms as well, where it can reach a high density and low shear, thereby promoting self-gravitational instabilities. The result is the formation of giant spiral arm cloud complexes,...

  11. Galaxy Zoo: Dust in Spirals

    CERN Document Server

    Masters, Karen L; Bamford, Steven; Mosleh, Moein; Lintott, Chris J; Andreescu, Dan; Edmondson, Edward M; Keel, William C; Murray, Phil; Raddick, M Jordan; Schawinski, Kevin; Slosar, Anze; Szalay, Alexander S; Thomas, Daniel; Vandenberg, Jan

    2010-01-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination-dependence of optical colours for 24,276 well-resolved SDSS galaxies visually classified in Galaxy Zoo. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4 magnitudes for the ugri passbands. We split the sample into "bulgy" (early-type) and "disky" (late-type) spirals using the SDSS fracdeV (or f_DeV) parameter and show that the average face-on colour of "bulgy" spirals is redder than the average edge-on colour of "disky" spirals. This shows that the observed optical colour of a spiral galaxy is determined almost equally by the spiral type (via the bulge-disk ratio and stellar populations), and reddening due to dust. We find that both luminosity and spiral type affect the total amount of extinction, with "disky" spirals at M_r ~ -21.5 mags having the most reddening. This decrease of reddening for the most luminous spirals has not been observed before ...

  12. Spiral Microstrip Antenna with Resistance

    Science.gov (United States)

    Shively, David G. (Inventor)

    1998-01-01

    A spiral microstrip antenna having resistor elements embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

  13. Rebuilding Spiral Galaxies

    Science.gov (United States)

    2005-01-01

    Major Observing Programme Leads to New Theory of Galaxy Formation Summary Most present-day large galaxies are spirals, presenting a disc surrounding a central bulge. Famous examples are our own Milky Way or the Andromeda Galaxy. When and how did these spiral galaxies form? Why do a great majority of them present a massive central bulge? An international team of astronomers [1] presents new convincing answers to these fundamental questions. For this, they rely on an extensive dataset of observations of galaxies taken with several space- and ground-based telescopes. In particular, they used over a two-year period, several instruments on ESO's Very Large Telescope. Among others, their observations reveal that roughly half of the present-day stars were formed in the period between 8,000 million and 4,000 million years ago, mostly in episodic burst of intense star formation occurring in Luminous Infrared Galaxies. From this and other evidence, the astronomers devised an innovative scenario, dubbed the "spiral rebuilding". They claim that most present-day spiral galaxies are the results of one or several merger events. If confirmed, this new scenario could revolutionise the way astronomers think galaxies formed. PR Photo 02a/05: Luminosity - Oxygen Abundance Relation for Galaxies (VLT) PR Photo 02b/05: The Spiral Rebuilding Scenario A fleet of instruments How and when did galaxies form? How and when did stars form in these island universes? These questions are still posing a considerable challenge to present-day astronomers. Front-line observational results obtained with a fleet of ground- and space-based telescopes by an international team of astronomers [1] provide new insights into these fundamental issues. For this, they embarked on an ambitious long-term study at various wavelengths of 195 galaxies with a redshift [2] greater than 0.4, i.e. located more than 4000 million light-years away. These galaxies were studied using ESO's Very Large Telescope, as well as the

  14. Quarkyonic Chiral Spirals

    CERN Document Server

    Kojo, Toru; McLerran, Larry; Pisarski, Robert D

    2009-01-01

    We consider the formation of chiral density waves in Quarkyonic matter, which is a phase where cold, dense quarks experience confining forces. We model confinement following Gribov and Zwanziger, taking the gluon propagator, in Coulomb gauge and momentum space, as 1/(p^2)^2. We assume that the number of colors, N, is large, and that the quark chemical potential, mu, is much larger than renormalization mass scale, Lambda_QCD. To leading order in 1/N and Lambda_QCD, a gauge theory with Nf flavors of massless quarks in 3+1 dimensions naturally reduces to a gauge theory in 1+1 dimensions, with an enlarged flavor symmetry of SU(2Nf). Through an anomalous chiral rotation, in two dimensions a Fermi sea of massless quarks maps directly onto the corresponding theory in vacuum. A chiral condensate forms locally, and varies with the spatial position, z, as . Following Schon and Thies, we term this two dimensional pion condensate a (Quarkyonic) chiral spiral. Massive quarks also exhibit chiral spirals, with the magnitude...

  15. The perfect shape spiral stories

    CERN Document Server

    Hammer, Øyvind

    2016-01-01

    This book uses the spiral shape as a key to a multitude of strange and seemingly disparate stories about art, nature, science, mathematics, and the human endeavour. In a way, the book is itself organized as a spiral, with almost disconnected chapters circling around and closing in on the common theme. A particular strength of the book is its extremely cross-disciplinary nature - everything is fun, and everything is connected! At the same time, the author puts great emphasis on mathematical and scientific correctness, in contrast, perhaps, with some earlier books on spirals. Subjects include the mathematical properties of spirals, sea shells, sun flowers, Greek architecture, air ships, the history of mathematics, spiral galaxies, the anatomy of the human hand, the art of prehistoric Europe, Alfred Hitchcock, and spider webs, to name a few.

  16. Intracranial artery dissection

    NARCIS (Netherlands)

    Sikkema, T.; Uyttenboogaart, Maarten; Eshghi, O.; De Keyser, J.; Brouns, R.; van Dijk, J.M.C.; Luijckx, G. J.

    2014-01-01

    The aim of this narrative review is to evaluate the pathogenesis, clinical features, diagnosis, treatment and prognosis of intracranial artery dissection (IAD). IAD is a rare and often unrecognized cause of stroke or subarachnoid haemorrhage (SAH), especially in young adults. Two types of IAD can be

  17. Endoscopic submucosal dissection

    DEFF Research Database (Denmark)

    Pimentel-Nunes, Pedro; Dinis-Ribeiro, Mário; Ponchon, Thierry

    2015-01-01

    they are smaller than 10 mm if en bloc resection can be assured. However, ESGE recommends endoscopic submucosal dissection (ESD) as the first option, mainly to provide an en bloc resection with accurate pathology staging and to avoid missing important histological features (strong recommendation, moderate quality...

  18. Intracranial artery dissection

    NARCIS (Netherlands)

    Sikkema, T.; Uyttenboogaart, Maarten; Eshghi, O.; De Keyser, J.; Brouns, R.; van Dijk, J.M.C.; Luijckx, G. J.

    The aim of this narrative review is to evaluate the pathogenesis, clinical features, diagnosis, treatment and prognosis of intracranial artery dissection (IAD). IAD is a rare and often unrecognized cause of stroke or subarachnoid haemorrhage (SAH), especially in young adults. Two types of IAD can be

  19. Dissection of a Galaxy

    Science.gov (United States)

    2004-01-01

    Sometimes, the best way to understand how something works is to take it apart. The same is true for galaxies like NGC 300, which NASA's Spitzer Space Telescope has divided into its various parts. NGC 300 is a face-on spiral galaxy located 7.5 million light-years away in the southern constellation Sculptor. This false-color image taken by the infrared array camera on Spitzer readily distinguishes the main star component of the galaxy (blue) from its dusty spiral arms (red). The star distribution peaks strongly in the central bulge where older stars congregate, and tapers off along the arms where younger stars reside. Thanks to Spitzer's unique ability to sense the heat or infrared emission from dust, astronomers can now clearly trace the embedded dust structures within NGC 300's arms. When viewed at visible wavelengths, the galaxy's dust appears as dark lanes, largely overwhelmed by bright starlight. With Spitzer, the dust - in particular organic compounds called polycyclic aromatic hydrocarbons - can be seen in vivid detail (red). These organic molecules are produced, along with heavy elements, by the stellar nurseries that pepper the arms. The findings provide a better understanding of spiral galaxy mechanics and, in the future, will help decipher more distant galaxies, whose individual components cannot be resolved. This image was taken on Nov. 21, 2003 and is composed of photographs obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

  20. Spiral vane bioreactor

    Science.gov (United States)

    Morrison, Dennis R. (Inventor)

    1991-01-01

    A spiral vane bioreactor of a perfusion type is described in which a vertical chamber, intended for use in a microgravity condition, has a central rotating filter assembly and has flexible membranes disposed to rotate annularly about the filter assembly. The flexible members have end portions disposed angularly with respect to one another. A fluid replenishment medium is input from a closed loop liquid system to a completely liquid filled chamber containing microcarrier beads, cells and a fluid medium. Output of spent medium is to the closed loop. In the closed loop, the output and input parameters are sensed by sensors. A manifold permits recharging of the nutrients and pH adjustment. Oxygen is supplied and carbon dioxide and bubbles are removed and the system is monitored and controlled by a microprocessor.

  1. Reflections on love's spirals.

    Science.gov (United States)

    Kenny, Gerard

    2011-06-01

    This article seeks to explore how the experience of love and its expression might inform and guide reflection and inquiry into love. Despite the importance of love in our personal and professional lives, it remains a topic that has further scope for inquiry within nursing circles. The article takes as its catalyst an encounter that emerged out of a piece of research that was exploring individuals' experiences of becoming healers and the journey they undertook. One participant spoke deeply and profoundly of his experience of love, which generated for me a personal, experiential, and intellectual process of inquiry. The article seeks to try and create a synthesis between rational inquiry and subjective experience. It explores W. B. Yeats's notion of a gyre, a spiral, as an image and metaphor for integrating different conceptions and understandings of love. It seeks to illustrate how a more integrated understanding of love may open up spaces of inquiry that are more flexible, creative, and spontaneous.

  2. Spiral microfluidic nanoparticle separators

    Science.gov (United States)

    Bhagat, Ali Asgar S.; Kuntaegowdanahalli, Sathyakumar S.; Dionysiou, Dionysios D.; Papautsky, Ian

    2008-02-01

    Nanoparticles have potential applications in many areas such as consumer products, health care, electronics, energy and other industries. As the use of nanoparticles in manufacturing increases, we anticipate a growing need to detect and measure particles of nanometer scale dimensions in fluids to control emissions of possible toxic nanoparticles. At present most particle separation techniques are based on membrane assisted filtering schemes. Unfortunately their efficiency is limited by the membrane pore size, making them inefficient for separating a wide range of sizes. In this paper, we propose a passive spiral microfluidic geometry for momentum-based particle separations. The proposed design is versatile and is capable of separating particulate mixtures over a wide dynamic range and we expect it will enable a variety of environmental, medical, or manufacturing applications that involve rapid separation of nanoparticles in real-world samples with a wide range of particle components.

  3. Entoptic perceptions of spiral waves and rare inward spirals.

    Science.gov (United States)

    Pearce, Ida

    2015-06-01

    This report concerns Entoptic Rotating Spiral Waves as observed and documented by the author over a period of 46 years (1962-2008). The manifestations of these state-dependent, elusive rotating spiral entities were brief, emerging only during sleep-to-waking arousal epochs (in limbo). The images were seen only with closed lids in favorable ambient lighting-here, termed the umbral view. The clusters of rotating spiral entities emerge briefly to conscious view; their angular subtenses are estimated to be between 1° and 4°, and the rotations at ten-turns per second. Epochs of these activities commonly continued for about 20 s, with longevity of each visible entity up to 4 s. 90% of all observed entities were circular and outwardly levorotary; 5% were elliptical, appearing only as horizontal (prolate) entities. Overlapping units were rare, and were chiefly elliptical. Observations of twin spirals were also rare, seen in counter rotations, each twin inwardly rotating.

  4. On-chip spiral spectrometer

    CERN Document Server

    Redding, Brandon; Bromberg, Yaron; Sarma, Raktim; Cao, Hui

    2016-01-01

    We designed an on-chip spectrometer based on an evanescently-coupled multimode spiral waveguide. Interference between the modes in the waveguide forms a wavelength-dependent speckle pattern which can be used as a fingerprint to identify the input wavelength after calibration. Evanescent coupling between neighboring arms of the spiral enhances the temporal spread of light propagating through the spiral, leading to a dramatic increase in the spectral resolution. Experimentally, we demonstrated that a 250 {\\mu}m radius spiral spectrometer provides a resolution of 0.01 nm at a wavelength of 1520 nm. Spectra containing 40 independent spectral channels can be recovered simultaneously and the operation bandwidth can be increased further when measuring sparse spectra.

  5. Measuring with the spiral reader

    CERN Multimedia

    1974-01-01

    The spiral reader shown here was at the time, together with the Shivamatic scanning system, the basic equipment used for measuring bubble chamber pictures. Anne Anton sits at the table. (See Photo Archive 7408343.)

  6. Discovering Relationships Involving Baravelle Spirals

    Science.gov (United States)

    Wanko, Jeffrey J.

    2006-01-01

    This article details an exploration of Baravelle spirals as visual representations of infinite geometric series, focusing on a variety of strategies used by preservice teachers in discovering patterns and investigating relationships of variables.

  7. Analytical approximations for spiral waves

    Energy Technology Data Exchange (ETDEWEB)

    Löber, Jakob, E-mail: jakob@physik.tu-berlin.de; Engel, Harald [Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, EW 7-1, 10623 Berlin (Germany)

    2013-12-15

    We propose a non-perturbative attempt to solve the kinematic equations for spiral waves in excitable media. From the eikonal equation for the wave front we derive an implicit analytical relation between rotation frequency Ω and core radius R{sub 0}. For free, rigidly rotating spiral waves our analytical prediction is in good agreement with numerical solutions of the linear eikonal equation not only for very large but also for intermediate and small values of the core radius. An equivalent Ω(R{sub +}) dependence improves the result by Keener and Tyson for spiral waves pinned to a circular defect of radius R{sub +} with Neumann boundaries at the periphery. Simultaneously, analytical approximations for the shape of free and pinned spirals are given. We discuss the reasons why the ansatz fails to correctly describe the dependence of the rotation frequency on the excitability of the medium.

  8. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, Noreddine

    2015-08-20

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body is configured to receive water and a disinfectant at the inlet such that the water is exposed to the disinfectant as the water flows through the spiral flow path. Also disclosed are processes for disinfecting water in such disinfection reactors.

  9. Magnetic fields in spiral galaxies

    Science.gov (United States)

    Beck, Rainer

    2015-12-01

    Radio synchrotron emission, its polarization and Faraday rotation of the polarization angle are powerful tools to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30 \\upmu G) and in central starburst regions (50-100 \\upmu G). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15 \\upmu G) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the intergalactic medium.—Faraday rotation measures of the diffuse polarized radio emission from galaxy disks reveal large-scale spiral patterns that can be described by the superposition of azimuthal modes; these are signatures of regular fields generated by mean-field dynamos. "Magnetic arms" between gaseous spiral arms may also be products of dynamo action, but need a stable spiral pattern to develop. Helically twisted field loops winding around spiral arms were found in two galaxies so far. Large-scale field reversals, like the one found in the Milky Way, could not yet be detected in external galaxies. In radio halos around edge-on galaxies, ordered magnetic fields with X-shaped patterns are observed. The origin and evolution of cosmic magnetic fields, in particular their first occurrence in young galaxies and their dynamical importance during galaxy evolution, will be studied with

  10. Aortic dissection: magnetic resonance imaging.

    Science.gov (United States)

    Amparo, E G; Higgins, C B; Hricak, H; Sollitto, R

    1985-05-01

    Fifteen patients with suspected or known aortic dissection were imaged with magnetic resonance (MR). Thirteen of these patients were eventually shown to have dissection. In most instances the diagnosis was established by aortography and/or computed tomography (CT) prior to the MR study. Surgical proof (6/13) and/or aortographic proof (10/13) were available in 11/13 patients with aortic dissection. MR demonstrated the intimal flap and determined whether the dissection was type A or type B. In addition, MR: differentiated between the true and false lumens; determined the origins of the celiac, superior mesenteric, and renal arteries from the true or false lumen in the cases where the dissection extended into the abdominal aorta (8/12); allowed post-surgical surveillance of the dissection; and identified aortoannular ectasia in the three patients who had Marfan syndrome. In addition to the 13 cases with dissection, there were two cases in whom the diagnosis of dissection was excluded by MR. Our early experience suggests that MR can serve as the initial imaging test in clinically suspected cases of aortic dissection and that the information provided by MR is sufficient to manage many cases. Additionally, MR obviates the use of iodinated contrast media.

  11. Similar dissection of sets

    CERN Document Server

    Akiyama, Shigeki; Okazaki, Ryotaro; Steiner, Wolfgang; Thuswaldner, Jörg

    2010-01-01

    In 1994, Martin Gardner stated a set of questions concerning the dissection of a square or an equilateral triangle in three similar parts. Meanwhile, Gardner's questions have been generalized and some of them are already solved. In the present paper, we solve more of his questions and treat them in a much more general context. Let $D\\subset \\mathbb{R}^d$ be a given set and let $f_1,...,f_k$ be injective continuous mappings. Does there exist a set $X$ such that $D = X \\cup f_1(X) \\cup ... \\cup f_k(X)$ is satisfied with a non-overlapping union? We prove that such a set $X$ exists for certain choices of $D$ and $\\{f_1,...,f_k\\}$. The solutions $X$ often turn out to be attractors of iterated function systems with condensation in the sense of Barnsley. Coming back to Gardner's setting, we use our theory to prove that an equilateral triangle can be dissected in three similar copies whose areas have ratio $1:1:a$ for $a \\ge (3+\\sqrt{5})/2$.

  12. Simulations of Normal Spiral Galaxies

    CERN Document Server

    Bottema, R

    2003-01-01

    Results are presented of numerical simulations of normal isolated late type spiral galaxies. Specifically the galaxy NGC 628 is used as a template. The method employs a TREESPH code including stellar particles, gas particles, cooling and heating of the gas, star formation according to a Jeans criterion, and Supernova feedback. A regular spiral disc can be generated as an equilibrium situation of two opposing actions. On the one hand cooling and dissipation of the gas, on the other hand gas heating by the FUV field of young stars and SN mechanical forcing. The disc exhibits small and medium scale spiral structure of which the multiplicity increases as a function of radius. The theory of swing amplification can explain, both qualitatively and quantitatively, the emerging spiral structure. In addition, swing amplification predicts that the existence of a grand design m=2 spiral is only possible if the disc is massive. The simulations show that the galaxy is then unstable to bar formation. A general criterion is ...

  13. Orientation decoding: Sense in spirals?

    Science.gov (United States)

    Clifford, Colin W G; Mannion, Damien J

    2015-04-15

    The orientation of a visual stimulus can be successfully decoded from the multivariate pattern of fMRI activity in human visual cortex. Whether this capacity requires coarse-scale orientation biases is controversial. We and others have advocated the use of spiral stimuli to eliminate a potential coarse-scale bias-the radial bias toward local orientations that are collinear with the centre of gaze-and hence narrow down the potential coarse-scale biases that could contribute to orientation decoding. The usefulness of this strategy is challenged by the computational simulations of Carlson (2014), who reported the ability to successfully decode spirals of opposite sense (opening clockwise or counter-clockwise) from the pooled output of purportedly unbiased orientation filters. Here, we elaborate the mathematical relationship between spirals of opposite sense to confirm that they cannot be discriminated on the basis of the pooled output of unbiased or radially biased orientation filters. We then demonstrate that Carlson's (2014) reported decoding ability is consistent with the presence of inadvertent biases in the set of orientation filters; biases introduced by their digital implementation and unrelated to the brain's processing of orientation. These analyses demonstrate that spirals must be processed with an orientation bias other than the radial bias for successful decoding of spiral sense.

  14. Spiral Inflector For Compact Cyclotron

    CERN Document Server

    Karamysheva, G A

    2004-01-01

    Compact cyclotron for explosives detection by nuclear resonance absorption of γ-rays in nitrogen is under development [1] Cyclotron will be equipped with the external ion source. The injection system consists of a double-drift beam bunching system, a spiral inflector, beam diagnostics, focusing and adjustment elements [2]. The spiral inflector for ion bending from axial to median plane is used. Computer model of spiral inflector for the Customs cyclotron is developed. 3D electrostatic field calculations of the designed inflector are performed. Calculated electric field map and magnetic field map of the cyclotron [3] are used for beam dynamic simulations. Numeric simulations are carried out for 500 particles using code for calculation of particle dynamics by integration of differential equations in Cartesian coordinate system written in MATLAB. Direct Coulomb particle-to-particle method is used to take into account space-charge effects.

  15. Transient spirals as superposed instabilities

    CERN Document Server

    Sellwood, J A

    2014-01-01

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the super-position of a few transient spiral modes. Each mode lasts between five and ten rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features, allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with l...

  16. Magnetic Fields in Spiral Galaxies

    CERN Document Server

    Beck, Rainer

    2015-01-01

    Radio synchrotron emission is a powerful tool to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30\\mu G) and in central starburst regions (50-100\\mu G). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15\\mu G) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies, and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the interg...

  17. "Dissection" of a Hair Dryer

    Science.gov (United States)

    Eisenstein, Stan; Simpson, Jeff

    2008-01-01

    The electrical design of the common hair dryer is based almost entirely on relatively simple principles learned in introductory physics classes. Just as biology students dissect a frog to see the principles of anatomy in action, physics students can "dissect" a hair dryer to see how principles of electricity are used in a real system. They can…

  18. Isolated superior mesenteric artery dissection

    Directory of Open Access Journals (Sweden)

    Lalitha Palle

    2010-01-01

    Full Text Available Isolated superior mesenteric artery (SMA dissection without involvement of the aorta and the SMA origin is unusual. We present a case of an elderly gentleman who had chronic abdominal pain, worse after meals. CT angiography, performed on a 64-slice CT scanner, revealed SMA dissection with a thrombus. A large artery of Drummond was also seen. The patient was managed conservatively.

  19. Spontaneous Coronary Artery Dissection.

    Science.gov (United States)

    Tweet, Marysia S; Gulati, Rajiv; Hayes, Sharonne N

    2016-07-01

    Spontaneous coronary artery dissection is an important etiology of nonatherosclerotic acute coronary syndrome, myocardial infarction, and sudden death. Innovations in the catheterization laboratory including optical coherence tomography and intravascular ultrasound have enhanced the ability to visualize intimal disruption and intramural hematoma associated with SCAD. Formerly considered "rare," these technological advances and heightened awareness suggest that SCAD is more prevalent than prior estimates. SCAD is associated with female sex, young age, extreme emotional stress, or extreme exertion, pregnancy, and fibromuscular dysplasia. The clinical characteristics and management strategies of SCAD patients are different than for atherosclerotic heart disease and deserve specific consideration. This review will highlight recent discoveries about SCAD as well as describe current efforts to elucidate remaining gaps in knowledge.

  20. Automatic Dissection Of Plantlets

    Science.gov (United States)

    Batchelor, B. G.; Harris, I. P.; Marchant, J. A.; Tillett, R. D.

    1989-03-01

    Micropropagation is a technique used in horticulture for generating a monoclonal colony of plants. A tiny plantlet is cut into several parts, each of which is then replanted. At the moment, the cutting is performed manually. Automating this task would have significant economic benefits. A robot designed to dissect plants would need to be equipped with intelligent visual sensing. This article is concerned with the image acquisition and processing techniques which such a machine might use. A program, which can calculate where to cut a plant with an "open" structure, is presented. This is expressed in the ProVision language, which is described in another article presented at this conference. (Article 1002-65)

  1. Efficient Algorithm for Rectangular Spiral Search

    Science.gov (United States)

    Brugarolas, Paul; Breckenridge, William

    2008-01-01

    An algorithm generates grid coordinates for a computationally efficient spiral search pattern covering an uncertain rectangular area spanned by a coordinate grid. The algorithm does not require that the grid be fixed; the algorithm can search indefinitely, expanding the grid and spiral, as needed, until the target of the search is found. The algorithm also does not require memory of coordinates of previous points on the spiral to generate the current point on the spiral.

  2. Stellar Spirals in Triaxial Dark Matter Halos

    Science.gov (United States)

    Hu, Shaoran; Sijacki, Debora

    2017-03-01

    Two-armed grand-design spirals may form if the shape of its dark matter halo changes abruptly enough. The feasibility of such a mechanism is tested in realistic simulations. The interplay of such externally-driven spirals and self-induced transient spirals is then studied. Subhaloes are also found to lead to transient grand-design spiral structures when they impact the disk.

  3. Inspired Spirals. Teaching Art with Art.

    Science.gov (United States)

    Hubbard, Guy

    2001-01-01

    Discusses spirals in nature, man-made objects, and art. Focuses on art that incorporates the spiral, including works by M. C. Escher and Frank Lloyd Wright, an African headdress, and a burial urn. Describes activities to help students make spirals of their own, such as constructing a coil clay pot. (CMK)

  4. Scale height determination of spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    计朝晖; 商朝晖; 彭秋和

    1997-01-01

    The method adopted here is based on the rigorous solution of Poison’s equation for logarithmic disturbance density within finite thickness galaxies. After their spiral arms are fitted directly with logarithmic spirals, the morphological parameters, scale heights and their relative errors for 32 spiral galaxies, such as NGC4814, are ob-tained.

  5. Spiral ganglion outgrowth and hearing development in p75-deficient mice.

    Science.gov (United States)

    Brors, Dominik; Hansen, Stefan; Mlynski, Robert; Volkenstein, Stefan; Aletsee, Christoph; Sendtner, Michael; Ryan, Allen F; Dazert, Stefan

    2008-01-01

    To explore the role of nerve growth factor receptor p75(NTR) during the terminal neuronal development of the mammalian cochlea the onset of hearing and the in vitro response of spiral ganglion neurites to neurotrophin 3 (NT-3), which is known to play a critical role during neonatal inner ear development, were investigated in p75(NTR)-deficient mice (p75(NTR)-/-). Auditory-evoked brain stem response recordings from p75(NTR)-/- and wild-type (WT) littermates were measured from postnatal days (PD) 8 to 23. Additionally, spiral ganglion explants from p75(NTR)-/- and WT animals were dissected and cultured in an organotypic tissue culture system. In both groups, spiral ganglion neurite outgrowth was analyzed with and without NT-3 supplementation. No significant differences in the onset of hearing of mutant mice compared to the WT mice were detected, and both groups showed a similar development of hearing until PD 23. After stimulation with NT-3, neurite outgrowth was enhanced in both p75(NTR)-/- and WT mice. However, neurites from p75(NTR)-/- spiral ganglion explants were longer in both culture conditions. Moreover, NT-3 did not significantly enhance neurite number in p75(NTR)-/-, as it did in WT mice. P75(NTR) has a remarkable influence on spiral ganglion neurite growth behavior. However, p75(NTR) does not seem to be essential for the development of basic hearing function in the first 3 postnatal weeks.

  6. Solitons in spiraling Vogel lattices

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2012-01-01

    We address light propagation in Vogel optical lattices and show that such lattices support a variety of stable soliton solutions in both self-focusing and self-defocusing media, whose propagation constants belong to domains resembling gaps in the spectrum of a truly periodic lattice. The azimuthally-rich structure of Vogel lattices allows generation of spiraling soliton motion.

  7. The enigma of auroral spirals

    Science.gov (United States)

    Haerendel, G.

    One of the most spectacular forms that the aurora borealis can assume is the large-scale spiral Spirals are dominantly observed along the poleward boundary of the auroral oval during active periods Two concepts have been pursued in explaining their origin and in particular the counterclockwise sense of rotation of the luminous structures when viewed along the magnetic field direction An essentially magnetostatic theory following Hallinan 1976 attributes the spiral pattern to the twisting of field-lines caused by a centrally located upward field-aligned current According to Oguti 1981 and followers a clockwise rotation of the plasma flow produces the anticlockwise structure There are observations seemingly confirming or contradicting either theory In this paper it is argued that both concepts are insufficient in that only parts of the underlying physics are considered Besides field-aligned currents and plasma flow one has to take into at least two further aspects The ionospheric conductivity modified by particle precipitation has an impact on the magnetospheric plasma dynamics Furthermore auroral arcs are not fixed entities subject to distortions by plasma flows or twisted field-lines but sites of transient releases of energy We suggest that auroral spirals are ports of entry or exit of plasma into or out of the auroral oval This way it can be understood why a clockwise plasma flow can create an anticlockwise luminous pattern

  8. Is Dissection a Must for Better Knowledge Among Future Doctors?

    Directory of Open Access Journals (Sweden)

    Hasan Barkat Irfan Deeba

    2011-01-01

    Full Text Available While the importance of anatomy education in contemporary medicine remains undisputable, the medium used to deliver anatomy information to medical learners is rapidly changing .The traditional dissection lies in the midst of a downward spiral as modern technological teaching alternatives rapidly substitute the cadaver. In this climate of pedagogical metamorphosis, the long-term cognitive impact of a ‘cadaver less' curriculum in the assimilation of core knowledge among our future physicians and surgeons remains an issue of fervent debate.The authors propose the hypothesis that active cadaveric dissection directly enhances the ‘long term learning outcomes' among students and is indispensible to the creation and retention of anatomy memory in the minds of learners. This retention of core concepts is not attainable through other instructional aids and might go a long way in framing the professional character of our medical community and the fate of our patients.To prove the same, this study provides objective evidence based on measurable data regarding the medical student's pedagogic preferences in anatomy education and their superior academic performance with the aid of dissection, thereby indicating the pivotal role of the cadaver in enhancing cognitive outcomes.

  9. On Generalized Euler Spirals in E^3

    OpenAIRE

    Saracoglu, Semra

    2012-01-01

    The Cornu spirals on plane are the curves whose curvatures are linear. Generalized planar cornu spirals and Euler spirals in E^3, the curves whose curvatures are linear are defined in [1,5]. In this study, these curves are presented as the ratio of two rational linear functions. Also here, generalized Euler spirals in E^3 has been defined and given their some various characterizations. The approach I used in this paper is useful in understanding the role of Euler spirals in E^3 in differentia...

  10. Spontaneous isolated celiac artery dissection

    Directory of Open Access Journals (Sweden)

    Tuba Cimilli Ozturk

    2011-01-01

    Full Text Available Dyspepsia with mild, stabbing epigastric discomfort without history of trauma is a very common symptom that emergency physicians see in their daily practice. Vascular emergencies, mostly the aortic dissection and aneurysm, are always described in the differential diagnosis with persistent symptoms. Isolated celiac artery dissection occurring spontaneously is a very rare diagnosis. The involvement of branch vessels is generally observed and patients show various clinical signs and symptoms according to the involved branch vessel. Here we are presenting a case with spontaneous isolated celiac artery dissection, without any branch vessel involvement or visceral damage, detected by computed tomography scans taken on admission.

  11. Interaction of multiarmed spirals in bistable media.

    Science.gov (United States)

    He, Ya-feng; Ai, Bao-quan; Liu, Fu-cheng

    2013-05-01

    We study the interaction of both dense and sparse multiarmed spirals in bistable media modeled by equations of the FitzHugh-Nagumo type. A dense one-armed spiral is characterized by its fixed tip. For dense multiarmed spirals, when the initial distance between tips is less than a critical value, the arms collide, connect, and disconnect continuously as the spirals rotate. The continuous reconstruction between the front and the back drives the tips to corotate along a rough circle and to meander zigzaggedly. The rotation frequency of tip, the frequency of zigzagged displacement, the frequency of spiral, the oscillation frequency of media, and the number of arms satisfy certain relations as long as the control parameters of the model are fixed. When the initial distance between tips is larger than the critical value, the behaviors of individual arms within either dense or sparse multiarmed spirals are identical to that of corresponding one-armed spirals.

  12. Localized spirals in Taylor-Couette flow.

    Science.gov (United States)

    Heise, M; Abshagen, J; Küter, D; Hochstrate, K; Pfister, G; Hoffmann, Ch

    2008-02-01

    We present a type of spiral vortex state that appears from a supercritical Hopf bifurcation below the linear instability of circular Couette flow in a Taylor-Couette system with rigid end plates. These spirals have been found experimentally as well as numerically as "pure" states but also coexist with "classical" spirals (or axially standing waves for smaller systems) which typically appear from linear instability in counterrotating Taylor-Couette flow. These spiral states have an axial distribution of the strongly localized amplitude in the vicinity of the rigid end plates that confine the system in the axial direction. Furthermore, they show significantly different oscillation frequencies compared to the critical spiral frequencies. Despite the localization of the amplitude near the ends, the states appear as global states with spirals that propagate either toward the middle from each end of the system or vice versa. In contrast to classical spirals, these states exhibit a spatial or a spatiotemporal reflection symmetry.

  13. Spiral Galaxies as Chiral Objects?

    CERN Document Server

    Capozziello, S; Capozziello, Salvatore; Lattanzi, Alessandra

    2005-01-01

    Spiral galaxies show axial symmetry and an intrinsic 2D-chirality. Environmental effects can influence the chirality of originally isolated stellar systems and a progressive loss of chirality can be recognised in the Hubble sequence. We point out a preferential modality for genetic galaxies as in microscopic systems like aminoacids, sugars or neutrinos. This feature could be the remnant of a primordial symmetry breaking characterizing systems at all scales.

  14. Spiral mining for lunar volatiles

    Science.gov (United States)

    Schmitt, H. H.; Kulcinski, G. L.; Sviatoslavsky, I. N.; Carrier, W. D., III

    Lunar spiral mining, extending outward from a periodically mobile central power and processing station represents an alternative for comparison with more traditional mining schemes. In this concept, a mining machine would separate regolith fines and extract the contained volatiles. Volatiles then would be pumped along the miner's support arm to the central station for refining and for export or storage. The basic architecture of the central processing station would be cylindrical. A central core area could house the power subsystem of hydrogen-oxygen engines or fuel cells. Habitat sections and other crew occupied areas could be arranged around the power generation core. The outer cylinder could include all volatile refining subsystems. Solar thermal power collectors and reflectors would be positioned on top of the central station. Long term exploitation of a volatile resource region would begin with establishment of a support base at the center of a long boundary of the region. The mining tract for each spiral mining system would extend orthogonal to this boundary. New spiral mining systems would be activated along parallel tracts as demand for lunar He-3 and other solar wind volatiles increased.

  15. Transient spirals as superposed instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Sellwood, J. A. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Carlberg, R. G., E-mail: sellwood@physics.rutgers.edu, E-mail: carlberg@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)

    2014-04-20

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the superposition of a few transient spiral modes. Each mode lasts between 5 and 10 rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with low-mass disks.

  16. Assessing beef carcass tissue weights using computed tomography spirals of primal cuts.

    Science.gov (United States)

    Navajas, E A; Glasbey, C A; Fisher, A V; Ross, D W; Hyslop, J J; Richardson, R I; Simm, G; Roehe, R

    2010-01-01

    More than 800 beef primal cuts from 44 Aberdeen Angus and Limousin-cross steers carcasses were scanned using spiral computed tomography (CT) and dissected. Thresholds for the segmentation of fat, muscle and bone in the CT spirals were estimated with the objective of assessing the weight of these tissues in the primal cuts and in the entire carcasses. Thresholds were estimated using half of the dataset (DBE) and then validated in the other half (DBV). Automatic image analysis procedures were used to assess tissue weights. The R(2) of the regression between primal tissue weight by dissection and CT were high in both datasets for fat (DBE, 0.89; DBV, 0.92), muscle (DBE, 0.99; DBV, 0.99) and bone (DBE, 0.95; DBV, 0.97). The estimation of total carcass tissue weights were also very accurate for the three tissues (R(2) values of 0.95 to 0.96), indicating that CT scanning may deliver very accurate information on beef carcass composition faster and with lower cost than physical dissection and without damaging or depreciating the primal joints.

  17. Spiral modes and the Milky Way

    Science.gov (United States)

    Lin, C. C.

    Recent refinements of the density-wave theory of galactic spiral modes are reviewed, and their implications for models of the structure of the Milky Way are investigated. The quasi-stationary-spiral-structure hypothesis, the structure of D100, the WASER excitation mechanisms of pure trailing spirals and rudimentary barred spirals, and modal calculations are discussed. For the Milky Way, the finding of a one-armed spiral mode causing kinematical-distance asymmetry, and some observational verifications of the spiral-gravitational-field (SGF) model for the region within about 3 kpc of the sun are reported. The importance of constructing a plausible SGF model, rather than using a circular model, for the study of the outer regions of the Milky Way is stressed. The addition of a large halo or corona to the Galactic-mass-distribution model is found to imply only scale changes in the density-wave SGF model.

  18. RESEARCH AND IMPROVEMENT OF SPIRAL BUNKER

    Institute of Scientific and Technical Information of China (English)

    董正筑; 曹璎珞; 王启广

    1996-01-01

    A great attention has been paid to slowing the degradation of coal nowadays. The spiral bunker is the main measure to lower the degradation. In this paper the application and research of spiral bunker are introduced. And two non-normal spiral chutes are discussed. One is in the tangential direction of the inner wall of the bunker, another is in the direction of the diameter of the bunker. Mathematical models of the non-normal spiral chutes are set up to optimize the geometrical parameters of the spiral curved surface, which would ensure that coal travels smoothly to the bottom of the bunker. The results would be useful for designing and retrofitting the spiral bunker.

  19. Uncovering spiral structure in flocculent galaxies

    CERN Document Server

    Thornley, M D

    1996-01-01

    We present K'(2.1 micron) observations of four nearby flocculent spirals, which clearly show low-level spiral structure and suggest that kiloparsec-scale spiral structure is more prevalent in flocculent spirals than previously supposed. In particular, the prototypical flocculent spiral NGC 5055 is shown to have regular, two-arm spiral structure to a radius of 4 kpc in the near infrared, with an arm-interarm contrast of 1.3. The spiral structure in all four galaxies is weaker than that in grand design galaxies. Taken in unbarred galaxies with no large, nearby companions, these data are consistent with the modal theory of spiral density waves, which maintains that density waves are intrinsic to the disk. As an alternative, mechanisms for driving spiral structure with non-axisymmetric perturbers are also discussed. These observations highlight the importance of near infrared imaging for exploring the range of physical environments in which large-scale dynamical processes, such as density waves, are important.

  20. The DESIR Facility at SPIRAL2

    Indian Academy of Sciences (India)

    Bertram Blank; Desir

    2010-08-01

    The DESIR Collaboration proposes the construction of an experimental facility to exploit the low-energy beams from SPIRAL1, SPIRAL2 and S3. The high degree of purity required to push experiments towards the limits of stability will be achieved by the implementation in the SPIRAL2 production building of a high-efficiency RFQ cooler coupled to a high-resolution mass separator. Beams from the low-energy branch of the separator spectrometer S3 and from SPIRAL1 will allow complementary studies of refractory elements produced by means of fusion reactions as well as of light and intense exotic beams, respectively.

  1. Solvable Model of Spiral Wave Chimeras

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Laing, Carlo R.; Strogatz, Steven H.

    2010-01-01

    Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral...... can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core....

  2. Type of spiral wave with trapped ions.

    Science.gov (United States)

    Li, Yuting; Li, Haihong; Zhu, Yun; Zhang, Mei; Yang, Junzhong

    2011-12-01

    Pattern formation in ultracold quantum systems has recently received a great deal of attention. In this work, we investigate a two-dimensional model system simulating the dynamics of trapped ions. We find a spiral wave that is rigidly rotating, but with a peculiar core region in which adjacent ions oscillate in antiphase. The formation of this spiral wave is ascribed to the excitability previously reported by Lee and Cross. The breakup of the spiral wave is probed and, especially, an extraordinary scenario of the disappearance of the spiral wave, caused by spontaneous expansion of the antiphase core, is unveiled.

  3. Scale heights of 84 northern spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    马骏; 彭秋和

    1997-01-01

    Using the method proposed by Peng (1988) on the basis of density waves theory and the solution of three-dimensional Poisson s equation for a logarithmic disturbance of density,and analyzing the spiral patterns,the scale heights of 84 northern spiral galaxies,whose images are taken from the Digitized Sky Survey at Xinglong Observational Station of Beijing Observatory,are measured.The spiral arms of all these galaxies have been fitted on their photographs with some logarithmic spiral curves for getting their correct inclinations.

  4. Evolution of Spiral Waves in Excitable Systems

    Institute of Scientific and Technical Information of China (English)

    KEN Ji-Rong; ZHU Tao; MO Shu-Fan

    2009-01-01

    Spiral waves, whose rotation center can be regarded as a point defect, widely exist in various two-dimensional excitable systems. In this paper, by making use of Duan's topological current theory, we obtain the charge density of spiral waves and the topological inner structure of its topological charge. The evolution of spiral wave is also studied from the topological properties of a two-dimensional vector field. The spiral waves are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points of the two-dimensional vector field. Some applications of our theory are also discussed.

  5. Neskinchenna spiral u seredovyshchi z vtratamy [The endless spiral in environment with losses

    Directory of Open Access Journals (Sweden)

    A. V. Talaluiev

    1998-09-01

    Full Text Available Found dispersion equation that describes the endless spiral of losses in the environment. The analytical expression for the wave resistance spiral, seen as a long line in lossy environment, and analytical expressions for the fields in cylindrical coordinates. The question of coordination sources of RF energy spiral.

  6. Elimination of Spiral Waves and Competition between Travelling Wave Impulses and Spiral Waves

    Institute of Scientific and Technical Information of China (English)

    YUAN Guo-Yong; ZHANG Guang-Cai; WANG Guang-Rui; CHEN Shi-Gang; SUN Peng

    2005-01-01

    @@ The interaction between travelling wave impulses and spiral waves is studied and the results of their competition are related to the exciting period. From the results, it is known that the formation and development of spiral waves in cardiac tissue depend on the period by which the travelling wave impulses are excited. A method is proposed to eliminate spiral waves, which is easily operated.

  7. Spontaneous internal carotid artery dissection.

    Science.gov (United States)

    Khimenko, L P; Esham, H R; Ahmed, W

    2000-10-01

    Once considered uncommon, spontaneous dissection of the carotid artery is an increasingly recognized cause of stroke, headache, cranial nerve palsy, or ophthalmologic events, especially in young adults. Even in the presence of existing signs and symptoms, the diagnosis can be missed by experienced physicians of all specialties. We report a case of spontaneous internal carotid artery dissection in a 38-year-old woman with a cortical stroke and visual disturbances as initial symptoms. The diagnosis was confirmed by magnetic resonance imaging/angiography and by angiography. Prompt anticoagulation was instituted, and the patient had complete resolution of symptoms. Cervicocephalic arterial dissection should be included in the differential diagnosis of the causes of cerebrovascular events.

  8. Spiral 2 the scientific objectives

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-06-15

    The French ministry of research took the decision to build Spiral-2 in May 2005. Its construction costs are estimated to 130 million euros while its operating costs will near 8.5 million euros per year. The construction works will last 5 years. The Spiral-2 facility is based on a high power, superconducting driver Linac, which will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equal to 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, fast neutrons from the breakup of the 5 mA of deuterons impinging on a uranium carbide target will induce a rate of up to 10{sup 14} fissions/s. The radioactive ion beam intensities in the mass range from A = 60 to 140 will be of the order of 10{sup 6} to 10{sup 11} particles/s surpassing by one or two orders-of-magnitude any existing facility in the world. A direct irradiation of the UC{sub 2} target with {sup 3,4}He, {sup 6,7}Li or {sup 12}C may also be used. Different production targets will be used to produce high-intensity beams of light radioactive species with the Isol technique. The extracted radioactive ion beam will be accelerated to energies up to 20 MeV/nucleons by the existing Cime cyclotron. One of the most important features of the future Ganil accelerator complex will be the capability of delivering up to 5 stable or radioactive beams simultaneously in the energy range from the keV to several tens of MeV/nucleons. The document details also the future contribution of Spiral-2 concerning the structure of exotic nuclei, the thermodynamical aspects of nuclear matter, nucleosynthesis, the fundamental basic interactions, and the use of neutrons. (A.C.)

  9. ``Dissection'' of a Hair Dryer

    Science.gov (United States)

    Eisenstein, Stan; Simpson, Jeff

    2008-12-01

    The electrical design of the common hair dryer is based almost entirely on relatively simple principles learned in introductory physics classes. Just as biology students dissect a frog to see the principles of anatomy in action, physics students can "dissect" a hair dryer to see how principles of electricity are used in a real system. They can discover how engineers solve problems such as how to vary between low and high heat and fan speed by simply moving the position of a single switch. Principles of alternating versus direct current, series and parallel circuits, electrical safety, voltage dividing, ac rectification, power, and measurement of resistance and continuity all come in to play.

  10. Emergency Physicians Think in Spirals.

    Science.gov (United States)

    Renouf, Tia; Whalen, Desmond; Pollard, Megan; Dubrowski, Adam

    2015-11-17

    As adult learners, junior clerks on core rotations in emergency medicine (EM) are expected to "own" their patients and follow them from presentation to disposition in the Emergency Department (ED). Traditionally, we teach clerks to present an exhaustive linear list of symptoms and signs to their preceptors. This does not apply well to the fast-paced ED setting. Mnemonics have been developed to teach clerks how to present succinctly and cohesively. To address the need for continual patient reassessment throughout the patient's journey in the ED, we propose a complimentary approach called SPIRAL.

  11. Spiral density waves in M81. I. Stellar spiral density waves

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Chien-Chang; Lin, Lien-Hsuan; Wang, Hsiang-Hsu; Taam, Ronald E., E-mail: hhwang@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan, R.O.C (China)

    2014-04-20

    Aside from the grand-design stellar spirals appearing in the disk of M81, a pair of stellar spiral arms situated well inside the bright bulge of M81 has been recently discovered by Kendall et al. The seemingly unrelated pairs of spirals pose a challenge to the theory of spiral density waves. To address this problem, we have constructed a three-component model for M81, including the contributions from a stellar disk, a bulge, and a dark matter halo subject to observational constraints. Given this basic state for M81, a modal approach is applied to search for the discrete unstable spiral modes that may provide an understanding for the existence of both spiral arms. It is found that the apparently separated inner and outer spirals can be interpreted as a single trailing spiral mode. In particular, these spirals share the same pattern speed 25.5 km s{sup –1} kpc{sup –1} with a corotation radius of 9.03 kpc. In addition to the good agreement between the calculated and the observed spiral pattern, the variation of the spiral amplitude can also be naturally reproduced.

  12. ANGULAR-MOMENTUM IN BINARY SPIRAL GALAXIES

    NARCIS (Netherlands)

    OOSTERLOO, T

    1993-01-01

    In order to investigate the relative orientations of spiral galaxies in pairs, the distribution of the angle between the spin-vectors for a new sample of 40 binary spiral galaxies is determined. From this distribution it is found, contrary to an earlier result obtained by Helou (1984), that there is

  13. QS Spiral: Visualizing Periodic Quantified Self Data

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Cuttone, Andrea; Jørgensen, Sune Lehmann

    2013-01-01

    In this paper we propose an interactive visualization technique QS Spiral that aims to capture the periodic properties of quantified self data and let the user explore those recurring patterns. The approach is based on time-series data visualized as a spiral structure. The interactivity includes ...

  14. Scaling effects in spiral capsule robots.

    Science.gov (United States)

    Liang, Liang; Hu, Rong; Chen, Bai; Tang, Yong; Xu, Yan

    2017-04-01

    Spiral capsule robots can be applied to human gastrointestinal tracts and blood vessels. Because of significant variations in the sizes of the inner diameters of the intestines as well as blood vessels, this research has been unable to meet the requirements for medical applications. By applying the fluid dynamic equations, using the computational fluid dynamics method, to a robot axial length ranging from 10(-5) to 10(-2) m, the operational performance indicators (axial driving force, load torque, and maximum fluid pressure on the pipe wall) of the spiral capsule robot and the fluid turbulent intensity around the robot spiral surfaces was numerically calculated in a straight rigid pipe filled with fluid. The reasonableness and validity of the calculation method adopted in this study were verified by the consistency of the calculated values by the computational fluid dynamics method and the experimental values from a relevant literature. The results show that the greater the fluid turbulent intensity, the greater the impact of the fluid turbulence on the driving performance of the spiral capsule robot and the higher the energy consumption of the robot. For the same level of size of the robot, the axial driving force, the load torque, and the maximum fluid pressure on the pipe wall of the outer spiral robot were larger than those of the inner spiral robot. For different requirements of the operating environment, we can choose a certain kind of spiral capsule robot. This study provides a theoretical foundation for spiral capsule robots.

  15. Tracing the spiral arms in IP Pegasi

    NARCIS (Netherlands)

    Baptista, R.; Morales-Rueda, L.; Harlaftis, E.T.; Marsh, T.R.; Steeghs, D.

    2005-01-01

    We report the analysis of time-resolved spectroscopy of IP Pegasi in outburst with eclipse mapping techniques to investigate the location and geometry of the observed spiral structures. We were able to obtain an improved view of the spiral structures with the aid of light curves extracted in

  16. Insights into acute aortic dissection

    NARCIS (Netherlands)

    Trimarchi, S.

    2012-01-01

    Aortic dissection represents one of the most catastrophic and complex cardiovascular diseases. Its origin is related to an intimal tear with course of blood flow into the aortic wall and division of the aortic lumen into two different lumens, defined as the true and false lumen, separated by a

  17. Animal Rights Activism Threatens Dissection.

    Science.gov (United States)

    Holden, Constance

    1990-01-01

    Discussed is the movement against the use of dissections in science laboratories. Examples of protests across the United States are included. Compared is the plight of using animals in a biology classroom and the demise of the teaching of evolution in some areas. (KR)

  18. Virtual dissection of pig carcasses

    DEFF Research Database (Denmark)

    Vester-Christensen, Martin; Erbou, Søren Gylling Hemmingsen; Hansen, Mads Fogtmann

    2009-01-01

    This paper proposes the use of computed tomography (CT) as a reference method for estimating the lean meat percentage (LMP) of pig carcasses. The current reference is manual dissection which has a limited accuracy due to variability between butchers. A contextual Bayesian classification scheme...

  19. Spontaneous aortic dissection within an infrarenal AAA.

    Science.gov (United States)

    Griffin, Kathryn J; Bailey, Marc A; McAree, Barry; Mekako, Anthony; Berridge, David C; Nicholson, Tony; Scott, D Julian A

    2012-12-01

    Aortic dissection occurring in the infrarenal abdominal aorta is uncommon. We present the case of a patient presenting with an enlarging abdominal aortic aneurysm and concurrent dissection (with associated radiological imaging) and briefly discuss the literature relating to this phenomenon.

  20. Dissection and preparation of viscera for plastination

    OpenAIRE

    Creus Tacies, Xavier

    2014-01-01

    Póster 1- Get a better understanding of the sistem coronary dissection, one of the most important from the point of anatomical and functional aspects. 2- Learn the plastination technique applying on a previously dissected equine heart.

  1. [Dissection is still important when learning anatomy].

    Science.gov (United States)

    Knudsen, Britt Mejer; Søe, Niels H; Jensen, Nina Vendel; Langebæk, Rikke; Dahlin, Lars B

    2013-05-20

    Dissection and prosection require a donation programme of cadavers for education and research. The importance of maintaining the donation programme and the significance of dissection as a teaching method when learning anatomic structures and obtaining surgical skills are evaluated.

  2. Quantitative analysis of spirality in elliptical galaxies

    CERN Document Server

    Dojcsak, Levente

    2013-01-01

    We use an automated galaxy morphology analysis method to quantitatively measure the spirality of galaxies classified manually as elliptical. The data set used for the analysis consists of 60,518 galaxy images with redshift obtained by the Sloan Digital Sky Survey (SDSS) and classified manually by Galaxy Zoo, as well as the RC3 and NA10 catalogues. We measure the spirality of the galaxies by using the Ganalyzer method, which transforms the galaxy image to its radial intensity plot to detect galaxy spirality that is in many cases difficult to notice by manual observation of the raw galaxy image. Experimental results using manually classified elliptical and S0 galaxies with redshift <0.3 suggest that galaxies classified manually as elliptical and S0 exhibit a nonzero signal for the spirality. These results suggest that the human eye observing the raw galaxy image might not always be the most effective way of detecting spirality and curves in the arms of galaxies.

  3. Termination of pinned spirals by local stimuli

    Science.gov (United States)

    Chen, Jiang-Xing; Guo, Ming-Ming; Ma, Jun

    2016-02-01

    The termination of pinned spirals on a defect by means of local stimuli is studied. On a completely unexcitable defect, the elimination process is discussed and its corresponding mechanism is presented. Especially, the mechanism of unpinning spirals on a partially unexcitable defect, which has not been investigated so far, is explored. With fixed pacing frequency ω L , there exists a maximal radius R max above which the pinned spiral cannot be removed. It is found that the value of R max does not increase as ω L in a dynamical regime, forming a platform in the R\\textit{max}\\text-ωL curves. Based on analyzing the dispersion relation on the spiral tip around the obstacle, the underlying mechanism is clarified. Also, it is found that when multiple spirals are pinned, the value of R max decreases on a partially unexcitable defect while the change is very slight on a completely unexcitable one.

  4. Illusory spirals and loops in crystal growth.

    Science.gov (United States)

    Shtukenberg, Alexander G; Zhu, Zina; An, Zhihua; Bhandari, Misha; Song, Pengcheng; Kahr, Bart; Ward, Michael D

    2013-10-22

    The theory of dislocation-controlled crystal growth identifies a continuous spiral step with an emergent lattice displacement on a crystal surface; a mechanistic corollary is that closely spaced, oppositely winding spirals merge to form concentric loops. In situ atomic force microscopy of step propagation on pathological L-cystine crystals did indeed show spirals and islands with step heights of one lattice displacement. We show by analysis of the rates of growth of smaller steps only one molecule high that the major morphological spirals and loops are actually consequences of the bunching of the smaller steps. The morphology of the bunched steps actually inverts the predictions of the theory: Spirals arise from pairs of dislocations, loops from single dislocations. Only through numerical simulation of the growth is it revealed how normal growth of anisotropic layers of molecules within the highly symmetrical crystals can conspire to create features in apparent violation of the classic theory.

  5. [Modern treatment of type B dissections

    DEFF Research Database (Denmark)

    Klitfod, L.; Baekgaard, N.; Just, S.

    2008-01-01

    Rapid classification is essential in the management of aortic dissections, as Type A dissections require surgery, while the optimal treatment of Type B dissections is controversial. Medical treatment with antihypertensive medication and analgesics has so far been the main treatment of uncomplicated...... Type B dissections, while surgery has been reserved for complications and persistent pain in spite of medical treatment. Endovascular techniques are less invasive than open repair and show promising early results Udgivelsesdato: 2008/9/8...

  6. [Modern treatment of type B dissections

    DEFF Research Database (Denmark)

    Klitfod, L.; Baekgaard, N.; Just, S.

    2008-01-01

    Rapid classification is essential in the management of aortic dissections, as Type A dissections require surgery, while the optimal treatment of Type B dissections is controversial. Medical treatment with antihypertensive medication and analgesics has so far been the main treatment of uncomplicated...... Type B dissections, while surgery has been reserved for complications and persistent pain in spite of medical treatment. Endovascular techniques are less invasive than open repair and show promising early results Udgivelsesdato: 2008/9/8...

  7. [Spinal accessory nerve and lymphatic neck dissection].

    Science.gov (United States)

    Pinsolle, V; Michelet, V; Majoufre, C; Caix, P; Siberchicot, F; Pinsolle, J

    1997-09-01

    Radical neck dissection was the golden standard of treatment for cervical nodes in head and neck tumors. From the seventies, the preservation of the spinal accessory nerve has become increasingly popular in order to improve the functional result of the neck dissections. The aim of this study was to assess the degree of functional disability associated with each type of neck dissection and the value of anatomical references for dissection of the spinal accessory nerve. One hundred twenty seven patients were evaluated 1 month and 1 year after radical, functional or supraomohyoid neck dissection with a questionnaire and a physical examination. Anatomical measurements of the spinal accessory nerve were performed in 20 patients. We found considerable or severe shoulder dysfunction in 7%, 34% and 51% respectively of patients in whom supraomohyoid, functional and radical neck dissections were performed. Furthermore 49% of patients having undergone a radical neck dissection had little or no symptoms. Sacrifice of the spinal accessory nerve in radical neck dissection may lead to shoulder dysfunction. A functional disability may also be associated, although in a less extent, with any neck dissection in which the spinal accessory nerve is dissected and placed in traction. There is a large variation in the degree of functional disability and pain in patients with similar neck dissections. The course of the spinal accessory nerve in the neck makes it particularly vulnerable to injury during the dissection near the sternocleidomastoid muscle and in the posterior cervical triangle.

  8. A Dissecting Competition for Medical Students

    Science.gov (United States)

    Samalia, Latika; Stringer, Mark D.

    2012-01-01

    After repeated requests from medical students for more cadaver dissection opportunities, a voluntary dissecting "competition" was initiated for the third year medical students in 2006. This has been held annually on five occasions since, offering up to 30 dissection stations and accommodating an average of 53 students (range 40-66) per year,…

  9. Solar Interactions on Spiral Petroglyphs

    Science.gov (United States)

    Davis, Brian F.; Preston, Robert A.

    2003-11-01

    Like most prehistoric cultures, the ancestors of the native Puebloan people of the Southwest were aware of the yearly cycle of the sun. This and other natural phenomena are fundamental for interpreting their world view, religion, and art. Some researchers have argued that rock art, particularly petroglyphs, displays this focus on the natural world through the distinctive interplay of sunlight on these carvings. However, the question of whether or not these interactions occur by intention or chance has hampered the acceptance of this evidence by the archaeological community. To address this question we have performed a detailed study of a complete sample of over 100 spiral petroglyphs within a limited area (less than 20 km^2) of central New Mexico. We have examined this sample on both solstices and equinoxes, and have observed well-defined and consistent sunlight interactions on about 80This work clearly demonstrates the reality and profusion of this ancient cultural tradition. Several examples will be presented.

  10. Reflections on dissection: leave no student behind.

    Science.gov (United States)

    Skandalakis, John E

    2008-01-01

    Dissection is being reduced--and even removed--from the medical curriculum in Australia, New Zealand, the United Kingdom, Ireland, and the United States. Dissection's contribution to the curriculum is too important to be diminished. To understand the human body, students must dissect. To avoid anatomical complications, future surgeons need the knowledge they can gain from dissection. Cadavers reveal the uniqueness of each body and the body's strength and fragility, which cannot be learned from books or computers. Cadavers offer surgical skill-building opportunities and confrontation with death. For all its strengths, however, dissection alone does not teach everything the student needs to know. Other educational tools (books, CT and MRI, animation of developmental processes) successfully fill in gaps of knowledge. Surgeons and educators must recognize the threat that decreased dissection poses to our students and patients. They must take steps to support dissection in the medical curriculum or, if it has disappeared, to bring it back.

  11. Acute spontaneous isolated dissection of abdominal aorta

    Directory of Open Access Journals (Sweden)

    Ali Akbar beigi

    2009-09-01

    Full Text Available

    • Aortic dissection occurs when the layers of the aorta separate as a result of extra luminal cavity of blood through an intimal tear. Dissection limited to the abdominal aorta is rare. Unfortunately, the appropriate management of dissecting aneurysm of abdominal aorta is not documented yet. A 43 years old man was admitted to Al-zahra hospital in Isfahan with sudden onset of periumbilical abdominal pain. CT scan confirmed infrarenal dissection of abdominal aorta. Performing laparotomy, aorta was repaired using bifurcate collagen-coated Dacron graft. Surgical intervention with synthetic graft is recommended in patients with dissecting aortic aneurysm of infrarenal segments where the extent of dissection is limited and accessible.
    • Keywords: Aneurysm, Aortic dissection, Aortic aneurysm abdominal surgery.

  12. [Pregnancy and coronary artery dissection].

    Science.gov (United States)

    Martínez-Quintana, Efrén; Rodríguez-González, Fayna

    2015-01-01

    Acute myocardial infarction during pregnancy is associated with high maternal and fetal mortality. Coronary atherosclerosis is the most common cause due to an increase in the age of the patients and the association with cardiovascular risk factors such as smoking, hypertension, diabetes mellitus, preeclampsia, and the existence of family history of coronary disease. However, thrombosis, coronary dissection or coronary vasospasms are other causes that may justify it. We report the case of a 33 weeks pregnant first-time mother, without cardiovascular risk factors, who presented an acute coronary event in the context of atherosclerotic disease and coronary dissection after percutaneous coronary intervention. Copyright © 2014 Sociedad Española de Arteriosclerosis. Published by Elsevier España. All rights reserved.

  13. Experimental Study on Spiral Patterns in Dielectric Barrier Discharge System

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Hua; DONG Li-Fang; LIU Fu-Cheng; LI Shu-Feng; LI Xue-Chen; WANG Hong-Fang

    2006-01-01

    Spiral patterns are obtained in a dielectric barrier discharge system with water electrodes. The dynamics of spiral formation and transition is investigated. Wavelength characteristic of spiral patterns is also studied. Correlation measurements indicate that the wavelength of spiral pattern increases with the increasing gas gap width and oscillates with the increasing drive frequency.

  14. Spiral Wave Dynamics in a Response System Subjected to a Spiral Wave Forcing

    Institute of Scientific and Technical Information of China (English)

    LI Guang-Zhao; CHEN Yong-Qi; TANG Guo-Ning; LIU Jun-Xian

    2011-01-01

    @@ Unidirectional linear error feedback coupling of two excitable medium systems displaying spiral waves is considered.The spiral wave in the response system is thus subjected to a spiral wave forcing.We find that the unidirectional feedback coupling can lead to richer behaviour than the mutual coupling.The spiral wave dynamics in the response system depends on the coupling strength and frequency mismatch.When the coupling strength is small, the feedback coupling induces the drift or meander of the forced spiral wave.When the coupling strength is large enough, the feedback coupling may lead to the transition from spiral wave to anti-target or target-like wave.The generation of anti-target wave in coupled excitable media is observed for the first time.Furthermore, when the coupling strength is strong, the synchronization between two subsystems can be established.%Unidirectional linear error feedback coupling of two excitable medium systems displaying spiral waves is considered. The spiral wave in the response system is thus subjected to a spiral wave forcing. We find that the unidirectional feedback coupling can lead to richer behaviour than the mutual coupling. The spiral wave dynamics in the response system depends on the coupling strength and frequency mismatch. When the coupling strength is small, the feedback coupling induces the drift or meander of the forced spiral wave. When the coupling strength is large enough, the feedback coupling may lead to the transition from spiral wave to anti-target or target-like wave. The generation of anti-target wave in coupled excitable media is observed for the first time. Furthermore,when the coupling strength is strong, the synchronization between two subsystems can be established.

  15. Intramyocardial Dissection following Postinfarction Ventricular Wall Rupture Contained by Surrounding Postoperative Adhesions

    Directory of Open Access Journals (Sweden)

    Abdulkadir Ercan

    2015-01-01

    Full Text Available Introduction. Dissection of the myocardium is a rare form of cardiac rupture, caused by a hemorrhagic dissection among the spiral myocardial fibers, its diagnosis is rarely established before the operation or death, and extremely few cases have been reported in the literature and none of these cases seem to have a history of previous cardiac surgery which makes our report unique. Case Presentation. A 61-year-old female patient was admitted into the emergency room with complaints of progressive chest pain for 2 days. She had a history of second time prosthetic aortic valve replacement and was under anticoagulation therapy. She was diagnosed with an acute inferoposterior myocardial infarction and underwent emergency coronary angiography revealing spontaneous recanalization of the right coronary artery. During the follow-up, she developed cardiogenic shock and a new occurring systolic ejection murmur. Transthoracic echocardiography showed a left ventricular free wall rupture; then, she was taken in for emergency surgery. During the operation, a rupture zone and a wide intramyocardial dissecting area were detected. Intraventricular patch repair technic with autologous pericardial patch was used to exclude the ruptured area. Following the warming period, despite adequate hemostasis, hemorrhage around suture lines progressively increased, leading to the patient’s death. Conclusion. Pericardial adhesions might contain left ventricular rupture leading to intramyocardial dissection.

  16. SPIRAL CONTACTOR FOR SOLVENT EXTRACTION COLUMN

    Science.gov (United States)

    Cooley, C.R.

    1961-06-13

    The patented extraction apparatus includes a column, perforated plates extending across the column, liquid pulse means connected to the column, and an imperforate spiral ribbon along the length of the column.

  17. Asymptotic theory for spiral wave reflections

    CERN Document Server

    Langham, Jacob; Barkley, Dwight

    2014-01-01

    Resonantly forced spiral waves in excitable media drift in straight-line paths, their rotation centers behaving as point-like objects moving along trajectories with a constant velocity. Interaction with medium boundaries alters this velocity and may often result in a reflection of the drift trajectory. Such reflections have diverse characteristics and are known to be highly non-specular in general. In this context we apply the theory of response functions, which via numerically computable integrals, reduces the reaction-diffusion equations governing the whole excitable medium to the dynamics of just the rotation center and rotation phase of a spiral wave. Spiral reflection trajectories are computed by this method for both small and large-core spiral waves. Such calculations provide insight into the process of reflection as well as explanations for differences in trajectories across parameters, including the effects of incidence angle and forcing amplitude. Qualitative aspects of these results are preserved fa...

  18. Featured Image: The Birth of Spiral Arms

    Science.gov (United States)

    Kohler, Susanna

    2017-01-01

    In this figure, the top panels show three spiral galaxies in the Virgo cluster, imaged with the Sloan Digital Sky Survey. The bottom panels provide a comparison with three morphologically similar galaxies generated insimulations. The simulations run by Marcin Semczuk, Ewa okas, and Andrs del Pino (Nicolaus Copernicus Astronomical Center, Poland) were designed to examine how the spiral arms of galaxies like the Milky Way may have formed. In particular, the group exploredthe possibility that so-called grand-design spiral arms are caused by tidal effects as a Milky-Way-like galaxy orbits a cluster of galaxies. The authors show that the gravitational potential of the cluster can trigger the formation of two spiral arms each time the galaxy passes through the pericenter of its orbit around the cluster. Check out the original paper below for more information!CitationMarcin Semczuk et al 2017 ApJ 834 7. doi:10.3847/1538-4357/834/1/7

  19. THE BIRTH AND DEATH PROCESSES OF HYPERCYCLE SPIRALS

    OpenAIRE

    KAZUMASA OIDA

    2003-01-01

    The behavior of hypercycle spirals in a two-dimensional cellular automaton model is analyzed. Each spiral can be approximated by an Archimedean spiral with center, width, and phase change according to Brownian motion. A barrier exists between two spirals if the phase synchronization hypothesis is taken into account, and the occurrence rate of pair decay (simultaneous disappearance of two spirals) can be explained through a random walk simulation with the barrier. Simulation experiments show t...

  20. Simulations of dual morphology in spiral galaxies

    CERN Document Server

    Berman, S L

    2003-01-01

    Gas and stars in spiral galaxies are modelled with the DUAL code, using hydrodynamic and N-body techniques. The simulations reveal morphological differences mirroring the dual morphologies seen in B and K' band observations of many spiral galaxies. In particular, the gaseous images are more flocculent with lower pitch angles than the stellar images, and the stellar arm-interarm contrast correlates with the degree of morphological decoupling.

  1. On Three-Dimensional Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-Lian; PENG Qiu-He; LONG Min; PENG Fang; ZOU Zhi-Gang

    2000-01-01

    Density waves in 3D spiral galaxies are studied. In order to eliminate the forbidden region near the corotation in the grand-design galaxies, we assume that the perturbation satisfies the stable condition Q(r) > 1 over all the disk except that at the corotation. Then, a new method is put forward here to determine some basic parameters of spiral galaxies. We apply it to our Galaxy, and the results are in good agreement with the previous results.

  2. View factors of cylindrical spiral surfaces

    Science.gov (United States)

    Lebedev, Vladimir A.; Solovjov, Vladimir P.

    2016-03-01

    Analytical expressions are presented for the view factors (radiative configuration factors) associated with the flat right cylindrical spiral surface. Such cylindrical spiral systems are widely applied as electrical resistance heating elements for lighting devices, electronic radio tubes, high-speed gas flow heaters, and other appliances used for scientific, industrial and domestic purposes. Derivation of the view factors is based on the invariant principles and the results presented in Lebedev (2000, 2003,1988) [1-3].

  3. Twisted Radiation by Electrons in Spiral Motion

    CERN Document Server

    Katoh, M; Mirian, N S; Konomi, T; Taira, Y; Kaneyasu, T; Hosaka, M; Yamamoto, N; Mochihashi, A; Takashima, Y; Kuroda, K; Miyamoto, A; Miyamoto, K; Sasaki, S

    2016-01-01

    We theoretically show that a single free electron in circular/spiral motion radiates an electromagnetic wave possessing helical phase structure and carrying orbital angular momentum. We experimentally demonstrate it by double-slit diffraction on radiation from relativistic electrons in spiral motion. We show that twisted photons should be created naturally by cyclotron/synchrotron radiations or Compton scatterings in various situations in astrophysics. We propose promising laboratory vortex photon sources in various wavelengths ranging from radio wave to gamma-rays.

  4. The distribution of prime numbers on the square root spiral

    CERN Document Server

    Hahn, Harry K

    2008-01-01

    Prime Numbers clearly accumulate on defined spiral graphs,which run through the Square Root Spiral. These spiral graphs can be assigned to different spiral-systems, in which all spiral-graphs have the same direction of rotation and the same -second difference- between the numbers, which lie on these spiral-graphs. A mathematical analysis shows, that these spiral graphs are caused exclusively by quadratic polynomials. For example the well known Euler Polynomial x2+x+41 appears on the Square Root Spiral in the form of three spiral-graphs, which are defined by three different quadratic polynomials. All natural numbers,divisible by a certain prime factor, also lie on defined spiral graphs on the Square Root Spiral (or Spiral of Theodorus, or Wurzelspirale). And the Square Numbers 4, 9, 16, 25, 36 even form a highly three-symmetrical system of three spiral graphs, which divides the square root spiral into three equal areas. Fibonacci number sequences also play a part in the structure of the Square Root Spiral. Wit...

  5. SIGNATURES OF LONG-LIVED SPIRAL PATTERNS

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Garcia, Eric E. [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue. (Mexico); Gonzalez-Lopezlira, Rosa A., E-mail: ericmartinez@inaoep.mx, E-mail: martinez@astro.unam.mx, E-mail: r.gonzalez@crya.unam.mx [Centro de Radioastronomia y Astrofisica, UNAM, Campus Morelia, Michoacan, C.P. 58089 (Mexico)

    2013-03-10

    Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a surface density stellar mass map. Mass maps were obtained from optical and near-infrared imaging, by comparison with a Monte Carlo library of stellar population synthesis models that allowed us to obtain the mass-to-light ratio in the J band, (M/L){sub J}, as a function of (g - i) versus (i - J) color. The selected spirals were analyzed with Fourier methods in search of other signatures of long-lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two-armed spiral in different wavebands, as expected from theory. The results show additional signatures of long-lived spirals in at least 50% of the objects.

  6. Fast magnetohydrodynamic density waves in spiral galaxies

    Science.gov (United States)

    Lou, Yu-Qing; Han, J. L.; Fan, Zuhui

    1999-09-01

    The newly observed large-scale structures of a southern grand-design spiral galaxy NGC 2997 in total and polarized radio-continuum emission together with their overall correlations with the known optical spiral structure are physically interpreted in terms of fast magnetohydrodynamic (MHD) density waves in contrast to slow MHD density waves in NGC 6946. The global spiral pattern of such fast MHD density waves extends from the very centre, where the disc rotates almost rigidly within ~0.5arcmin, all the way to the outer disc with a more or less flat rotation curve. To strengthen the case, several known features of spiral galaxies M51 and IC 342 are referred to and their pattern identifications discussed. It is emphasized that the nature of a magnetized spiral galaxy would be much better appreciated by examining large-scale structures in optical, atomic hydrogen Hi, total and polarized radio-continuum and infrared emission together. As various star-formation processes occur concurrently and/or sequentially in spiral arms of high gas concentration, relatively broad and fuzzy Hi arms, roughly coincident with optical arms in the inner disc, are expected to extend from the extremities of fading optical arms further into the outer gas disc. We predict that the south-east `magnetic arm', apparently isolated from any optical features, in total and polarized radio-continuum intensity maps of NGC 2997 should be associated with an Hi gas arm yet to be detected in 21-cm line emission.

  7. Arm & Interarm Star Formation in Spiral Galaxies

    CERN Document Server

    Foyle, Kelly; Walter, Fabian; Leroy, Adam

    2010-01-01

    We investigate the relationship between spiral arms and star formation in the grand-design spirals NGC 5194 and NGC 628 and in the flocculent spiral NGC 6946. Filtered maps of near-IR (3.6 micron) emission allow us to identify "arm regions" that should correspond to regions of stellar mass density enhancements. The two grand-design spirals show a clear two-armed structure, while NGC 6946 is more complex. We examine these arm and interarm regions, looking at maps that trace recent star formation - far-ultraviolet (GALEX NGS) and 24 micron emission (Spitzer, SINGS) - and cold gas - CO (Heracles) and HI (Things). We find the star formation tracers and CO more concentrated in the spiral arms than the stellar 3.6 micron flux. If we define the spiral arms as the 25% highest pixels in the filtered 3.6 micron images, we find that the majority (60%) of star formation tracers occurs in the interarm regions; this result persists qualitatively even when considering the potential impact of finite data resolution and diffu...

  8. Do Bars Drive Spiral Density Waves?

    CERN Document Server

    Buta, R J; Elmegreen, B G; Salo, H; Laurikainen, E; Elmegreen, D M; Puerari, I; Block, D L

    2009-01-01

    We present deep near-infrared K_s-band AAT IRIS2 observations of a selected sample of nearby barred spiral galaxies, including some with the strongest known bars. The sample covers a range of Hubble types from SB0- to SBc. The goal is to determine if the torque strengths of the spirals correlate with those of the bars, which might be expected if the bars actually drive the spirals as has been predicted by theoretical studies. This issue has implications for interpreting bar and spiral fractions at high redshift. Analysis of previous samples suggested that such a correlation exists in the near-infrared, where effects of extinction and star formation are less important. However, the earlier samples had only a few excessively strong bars. Our new sample largely confirms our previous studies, but still any correlation is relatively weak. We find two galaxies, NGC 7513 and UGC 10862, where there is a only a weak spiral in the presence of a very strong bar. We suggest that some spirals probably are driven by their ...

  9. Radial transport of dust in spiral galaxies

    CERN Document Server

    Vorobyov, E I; Shchekinov, Yu. A.

    2006-01-01

    Motivated by recent observations which detect dust at large galactocentric distances in the disks of spiral galaxies, we propose a mechanism of outward radial transport of dust by spiral stellar density waves. We consider spiral galaxies in which most of dust formation is localized inside the corotation radius. We show that in the disks of such spiral galaxies, the dust grains can travel over radial distances that exceed the corotation radius by roughly 25%. A fraction of the dust grains can be trapped on kidney-shaped stable orbits between the stellar spiral arms and thus can escape the destructive effect of supernova explosions. These grains form diffuse dusty spiral arms, which stretch 4-5 kpc from the sites of active star formation. About 10% of dust by mass injected inside corotation, can be transported over radial distances 3-4 kpc during approximately 1.0 Gyr. This is roughly an order of magnitude more efficient than can be provided by the turbulent motions.

  10. Spiral 2: preliminary design study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-11-15

    The scientific council of GANIL asked to perform a comparative study on the production methods based on gamma induced fission and rapid-neutron induced fission concerning the nature and the intensity of the neutron-rich products. The production rate expected should be around 10{sup 13} fissions per second. The study should include the implantation and the costs of the concerned accelerators. The scientific committee recommended also to study the possibility to re-inject the radioactive beams of SPIRAL-II in the cyclotrons available at GANIL in order to give access to an energy range from 1.7 to 100 MeV/nucleon. For that purpose, some study groups have been formed to evaluate the possibility of such a project in the different components: physics case, target-ion sources, drivers, post-acceleration and general infrastructure. The organization of the project study is given at the end of this report. The following report presents an overview of the study. Particularly the total costs have been assessed according to 3 options for the driver: 38.0*10{sup 6} euros for a 40 MeV deuteron linac, 18.7*10{sup 6} euros for a 45 MeV electron linac, and 29.1*10{sup 6} euros for a 80 MeV deuteron cyclotron.

  11. Six Decades of Spiral Density Wave Theory

    Science.gov (United States)

    Shu, Frank H.

    2016-09-01

    The theory of spiral density waves had its origin approximately six decades ago in an attempt to reconcile the winding dilemma of material spiral arms in flattened disk galaxies. We begin with the earliest calculations of linear and nonlinear spiral density waves in disk galaxies, in which the hypothesis of quasi-stationary spiral structure (QSSS) plays a central role. The earliest success was the prediction of the nonlinear compression of the interstellar medium and its embedded magnetic field; the earliest failure, seemingly, was not detecting color gradients associated with the migration of OB stars whose formation is triggered downstream from the spiral shock front. We give the reasons for this apparent failure with an update on the current status of the problem of OB star formation, including its relationship to the feathering substructure of galactic spiral arms. Infrared images can show two-armed, grand design spirals, even when the optical and UV images show flocculent structures. We suggest how the nonlinear response of the interstellar gas, coupled with overlapping subharmonic resonances, might introduce chaotic behavior in the dynamics of the interstellar medium and Population I objects, even though the underlying forces to which they are subject are regular. We then move to a discussion of resonantly forced spiral density waves in a planetary ring and their relationship to the ideas of disk truncation, and the shepherding of narrow rings by satellites orbiting nearby. The back reaction of the rings on the satellites led to the prediction of planet migration in protoplanetary disks, which has had widespread application in the exploding data sets concerning hot Jupiters and extrasolar planetary systems. We then return to the issue of global normal modes in the stellar disk of spiral galaxies and its relationship to the QSSS hypothesis, where the central theoretical concepts involve waves with negative and positive surface densities of energy and angular

  12. Spiral arms as cosmic ray source distributions

    Science.gov (United States)

    Werner, M.; Kissmann, R.; Strong, A. W.; Reimer, O.

    2015-04-01

    The Milky Way is a spiral galaxy with (or without) a bar-like central structure. There is evidence that the distribution of suspected cosmic ray sources, such as supernova remnants, are associated with the spiral arm structure of galaxies. It is yet not clearly understood what effect such a cosmic ray source distribution has on the particle transport in our Galaxy. We investigate and measure how the propagation of Galactic cosmic rays is affected by a cosmic ray source distribution associated with spiral arm structures. We use the PICARD code to perform high-resolution 3D simulations of electrons and protons in galactic propagation scenarios that include four-arm and two-arm logarithmic spiral cosmic ray source distributions with and without a central bar structure as well as the spiral arm configuration of the NE2001 model for the distribution of free electrons in the Milky Way. Results of these simulation are compared to an axisymmetric radial source distribution. Also, effects on the cosmic ray flux and spectra due to different positions of the Earth relative to the spiral structure are studied. We find that high energy electrons are strongly confined to their sources and the obtained spectra largely depend on the Earth's position relative to the spiral arms. Similar finding have been obtained for low energy protons and electrons albeit at smaller magnitude. We find that even fractional contributions of a spiral arm component to the total cosmic ray source distribution influences the spectra on the Earth. This is apparent when compared to an axisymmetric radial source distribution as well as with respect to the Earth's position relative to the spiral arm structure. We demonstrate that the presence of a Galactic bar manifests itself as an overall excess of low energy electrons at the Earth. Using a spiral arm geometry as a cosmic ray source distributions offers a genuine new quality of modeling and is used to explain features in cosmic ray spectra at the Earth

  13. IR STAR FORMING KNOTS IN GRAND DESIGN SPIRAL GALAXIES: SPIRAL STRUCTURE STAR FORMATION CONNECTION

    Directory of Open Access Journals (Sweden)

    H. Dottori

    2009-01-01

    Full Text Available We are studying 46 Grand Design spirals widely spread in types, which have been imaged in the K-band with the ESO NTT telescope. Eleven objects show knots strongly associated to the m=2 Fourier component of the spiral structure. Corotation ressonance (CR for the two-armed pattern have been derived for ve galaxies.

  14. Spontaneous Cervical Artery Dissection: The Borgess Classification

    Directory of Open Access Journals (Sweden)

    Firas eAl-Ali

    2013-09-01

    Full Text Available ABSTRACTBackground and Purpose: The pathogenesis of spontaneous cervical artery dissections (sCAD and its best medical treatment are debated. This may be due to a lack of clear classification of sCAD. We propose the new Borgess classification of sCAD, based on the presence or absence of intimal tear as depicted on imaging studies and effect on blood flow. Materials and Methods: This is a single-center investigator-initiated registry on consecutive patients treated for sCAD. In the Borgess classification, type I dissections have intact intima and type II dissections have an intimal tear. Results: Forty-four patients and 52 dissected arteries were found. Forty-nine of 52 dissections (93% were treated with dual anti-platelet therapy. Twenty-one of 52 dissections were type I; 31 were type II. Type I dissections were more likely to present with ischemic symptoms (stroke, TIA (p=0.001. More type I dissections occurred in the vertebral artery, while more type II dissections occurred in the internal carotid artery (p

  15. Evaluation of Educator & Student Use of & Attitudes toward Dissection & Dissection Alternatives

    Science.gov (United States)

    Osenkowski, Pamela; Green, Che; Tjaden, Anne; Cunniff, Peggy

    2015-01-01

    Animal dissection has been routinely practiced in American biology classrooms for decades. With technological advancements, more states adopting student choice measures, and increased awareness about ethical concerns surrounding dissection, many useful dissection alternatives have been developed. To understand the current use of animal dissection…

  16. Evaluation of Educator & Student Use of & Attitudes toward Dissection & Dissection Alternatives

    Science.gov (United States)

    Osenkowski, Pamela; Green, Che; Tjaden, Anne; Cunniff, Peggy

    2015-01-01

    Animal dissection has been routinely practiced in American biology classrooms for decades. With technological advancements, more states adopting student choice measures, and increased awareness about ethical concerns surrounding dissection, many useful dissection alternatives have been developed. To understand the current use of animal dissection…

  17. Observational Confirmations of Spiral Density Wave Theory

    Science.gov (United States)

    Kennefick, Julia D.; Kennefick, Daniel; Shameer Abdeen, Mohamed; Berrier, Joel; Davis, Benjamin; Fusco, Michael; Pour Imani, Hamed; Shields, Doug; DMS, SINGS

    2017-01-01

    Using two techniques to reliably and accurately measure the pitch angles of spiral arms in late-type galaxies, we have compared pitch angles to directly measured black hole masses in local galaxies and demonstrated a strong correlation between them. Using the relation thus established we have developed a pitch angle distribution function of a statistically complete volume limited sample of nearby galaxies and developed a central black hole mass function for nearby spiral galaxies.We have further shown that density wave theory leads us to a three-way correlation between bulge mass, pitch angle, and disk gas density, and have used data from the Galaxy Disk Mass Survey to confirm this possible fundamental plane. Density wave theory also predicts that the pitch angle of spiral arms should change with observed waveband as each waveband is sampling a different stage in stellar population formation and evolution. We present evidence that this is indeed the case using a sample of galaxies from the Spitzer Infrared Nearby Galaxy Survey. Furthermore, the evolved spiral arms cross at the galaxy co-rotation radius. This gives a new method for determining the co-rotation radius of spiral galaxies that is found to agree with those found using previous methods.

  18. Spiral Arms as Cosmic Ray Source Distributions

    CERN Document Server

    Werner, M; Strong, A W; Reimer, O

    2014-01-01

    There is evidence that the distribution of suspected cosmic ray sources are associated with the spiral arm structure of galaxies. It is yet not clearly understood what effect such a cosmic ray source distribution has on the particle transport in our Galaxy. We use the PICARD code to perform high-resolution 3D simulations of electrons and protons in galactic propagation scenarios that include four-arm and two-arm logarithmic spiral cosmic ray source distributions with and without a central bar structure as well as the spiral arm configuration of the NE2001 model for the distribution of free electrons in the Milky Way. Results of these simulation are compared to an axisymmetric radial source distribution. Also, effects on the cosmic ray flux and spectra due to different positions of the Earth relative to the spiral structure are studied. We find that high energy electrons are strongly confined to their sources and the obtained spectra largely depend on the Earth's position relative to the spiral arms. Similar f...

  19. Environmental factors and cervical artery dissection.

    Science.gov (United States)

    Caso, Valeria; Paciaroni, Maurizio; Bogousslavsky, Julien

    2005-01-01

    A history of a minor precipitating event is frequently elicited in patients with a spontaneous dissection of the carotid or vertebral artery. Other precipitating events associated with hyperextension or rotation of the neck include practicing yoga, painting a ceiling, coughing, vomiting, sneezing, the receipt of anesthesia, and the act of resuscitation. Chiropractic manipulation of the neck has been associated with carotid artery dissection and, particularly, vertebral artery dissection. Another risk factor for spontaneous dissections seems to be a recent history of a respiratory tract infection. The possibility of an infectious trigger is supported by the finding of a seasonal variation in the incidence of spontaneous dissections, with a peak incidence in fall. A potential link with common risk factors for vascular disease, such as tobacco use, hypertension, and the use of oral contraceptives, has not been systematically evaluated, but atherosclerosis appears to be distinctly uncommon in patients with a dissection of the carotid or vertebral arteries. In conclusion, although any hypotheses on the pathogenic mechanisms linking environmental factors and dissection remain speculative at present, we believe that these hypotheses may contribute to better define the spectrum of pathogenic conditions predisposing a cervical artery to dissection and provide arguments to better investigate the single or combined effect of such susceptibility factors in future studies.

  20. [Internal carotid artery dissection after Heimlich maneuver].

    Science.gov (United States)

    Rakotoharinandrasana, H; Petit, E; Dumas, P; Vandermarcq, P; Gil, R; Neau, J-Ph

    2003-01-01

    We report a case of cervical artery dissection following a Heimlich maneuver. Cervical artery dissections are at the present time well known and are sometimes associated with trivial traumas. However, to our knowledge, this complication of such maneuver was never reported in the literature. Pathophysiological mechanisms are discussed.

  1. Quick Dissection of the Segmental Bronchi

    Science.gov (United States)

    Nakajima, Yuji

    2010-01-01

    Knowledge of the three-dimensional anatomy of the bronchopulmonary segments is essential for respiratory medicine. This report describes a quick guide for dissecting the segmental bronchi in formaldehyde-fixed human material. All segmental bronchi are easy to dissect, and thus, this exercise will help medical students to better understand the…

  2. Nodal yield in selective neck dissection

    DEFF Research Database (Denmark)

    Norling, Rikke; Therkildsen, Marianne H; Bradley, Patrick J

    2013-01-01

    The total lymph node yield in neck dissection is highly variable and depends on anatomical, surgical and pathological parameters. A minimum yield of six lymph nodes for a selective neck dissection (SND) as recommended in guidelines lies in the lower range of the reported clinical nodal yields...

  3. Keeping Dissection Alive for Medical Students

    Science.gov (United States)

    Chambers, James; Emlyn-Jones, Daniel

    2009-01-01

    Traditional dissection teaching is being reduced in a number of medical schools, particularly in the United Kingdom. In response to this, 12 medical students from Warwick University, UK, traveled to the Island of Grenada for an intensive extracurricular dissection course at St. George's University. This course not only benefited the host…

  4. Keeping Dissection Alive for Medical Students

    Science.gov (United States)

    Chambers, James; Emlyn-Jones, Daniel

    2009-01-01

    Traditional dissection teaching is being reduced in a number of medical schools, particularly in the United Kingdom. In response to this, 12 medical students from Warwick University, UK, traveled to the Island of Grenada for an intensive extracurricular dissection course at St. George's University. This course not only benefited the host…

  5. Mathematical Modeling of Spiral Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Probal Guha , Vaishnavi Unde

    2014-04-01

    Full Text Available Compact Heat Exchangers (CHEs are increasingly being used on small and medium scale industries. Due to their compact size and efficient design, they facilitate more efficient heat transfer. Better heat transfer would imply lesser fuel consumption for the operations of the plant, giving improvement to overall efficiency. This reduction in consumption of fuel is a step towards sustainable development. This report exclusively deals with the study the spiral heat exchanger.The design considerations for spiral heat exchanger is that the flow within the spiral has been assumed as flow through a duct and by using Shah London empirical equation for Nusselt number design parameters are further optimized.This is accompanied by a detailed energy balance to generate a concise mathematical model

  6. Discontinuous spirals of stable periodic oscillations.

    Science.gov (United States)

    Sack, Achim; Freire, Joana G; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A C

    2013-11-27

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators.

  7. Discontinuous Spirals of Stable Periodic Oscillations

    Science.gov (United States)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A. C.

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators. PMID:24284508

  8. Cloud and Star Formation in Spiral Arms

    CERN Document Server

    Dobbs, Clare

    2014-01-01

    We present the results from simulations of GMC formation in spiral galaxies. First we discuss cloud formation by cloud-cloud collisions, and gravitational instabilities, arguing that the former is prevalent at lower galactic surface densities and the latter at higher. Cloud masses are also limited by stellar feedback, which can be effective before clouds reach their maximum mass. We show other properties of clouds in simulations with different levels of feedback. With a moderate level of feedback, properties such as cloud rotations and virial parameters agree with observations. Without feedback, an unrealistic population of overly bound clouds develops. Spiral arms are not found to trigger star formation, they merely gather gas into more massive GMCs. We discuss in more detail interactions of clouds in the ISM, and argue that these are more complex than early ideas of cloud-cloud collisions. Finally we show ongoing work to determine whether the Milky Way is a flocculent or grand design spiral.

  9. How Different are Normal and Barred Spirals?

    CERN Document Server

    Bergh, Sidney van den

    2011-01-01

    No significant color differences are found between normal and barred spirals over the range of Hubble stages a - ab - b - bc. Furthermore, no significant difference is seen between the luminosity distributions of normal and barred galaxies over the same range of Hubble stages. However, SBc galaxies are found to be systematically fainter than Sc galaxies at 99% confidence. The observation that normal and barred spirals with Hubble stages a - ab - b - bc have indistinguishable intrinsic colors hints at the possibility that the bars in such spiral galaxies might be ephemeral structures. Finally, it is pointed out that lenticular galaxies of types S0 and SB0 are systematically fainter than are other early-type galaxies, suggesting that such galaxies are situated on evolutionary tracks that differ systematically from those of galaxies that lie along the E - Sa - Sb -Sc and E - SBa - SBb - SBc sequences.

  10. Circularly symmetric light scattering from nanoplasmonic spirals.

    Science.gov (United States)

    Trevino, Jacob; Cao, Hui; Dal Negro, Luca

    2011-05-11

    In this paper, we combine experimental dark-field imaging, scattering, and fluorescence spectroscopy with rigorous electrodynamics calculations in order to investigate light scattering from planar arrays of Au nanoparticles arranged in aperiodic spirals with diffuse, circularly symmetric Fourier space. In particular, by studying the three main types of Vogel's spirals fabricated by electron-beam lithography on quartz substrates, we demonstrate polarization-insensitive planar light diffraction in the visible spectral range. Moreover, by combining dark-field imaging with analytical multiparticle calculations in the framework of the generalized Mie theory, we show that plasmonic spirals support distinctive structural resonances with circular symmetry carrying orbital angular momentum. The engineering of light scattering phenomena in deterministic structures with circular Fourier space provides a novel strategy for the realization of optical devices that fully leverage on enhanced, polarization-insensitive light-matter coupling over planar surfaces, such as thin-film plasmonic solar cells, plasmonic polarization devices, and optical biosensors.

  11. The finite element modeling of spiral ropes

    Institute of Scientific and Technical Information of China (English)

    Juan Wu

    2014-01-01

    Accurate understanding the behavior of spiral rope is complicated due to their complex geometry and complex contact conditions between the wires. This study proposed the finite element models of spiral ropes subjected to tensile loads. The parametric equations developed in this paper were implemented for geometric modeling of ropes. The 3D geometric models with different twisting manner, equal diameters of wires were generated in details by using Pro/ENGINEER software. The results of the present finite element analysis were on an acceptable level of accuracy as compared with those of theoretical and experimental data. Further development is ongoing to analysis the equivalent stresses induced by twisting manner of cables. The twisting manner of wires was important to spiral ropes in the three wire layers and the outer twisting manner of wires should be contrary to that of the second layer, no matter what is the first twisting manner of wires.

  12. Spontaneous Coronary Artery Dissection with Cardiac Tamponade.

    Science.gov (United States)

    Goh, Anne C H; Lundstrom, Robert J

    2015-10-01

    Spontaneous coronary artery dissection is a rare cause of acute coronary syndrome. Clinical presentation ranges from chest pain alone to ST-segment-elevation myocardial infarction, ventricular fibrillation, and sudden death. The treatment of patients with spontaneous coronary artery dissection is challenging because the disease pathophysiology is unclear, optimal treatment is unknown, and short- and long-term prognostic data are minimal. We report the case of a 70-year-old woman who presented with an acute ST-segment-elevation myocardial infarction secondary to a spontaneous dissection of the left anterior descending coronary artery. She was treated conservatively. Cardiac tamponade developed 16 hours after presentation. Repeat coronary angiography revealed extension of the dissection. Medical therapy was continued after the hemopericardium was aspirated. The patient remained asymptomatic 3 years after hospital discharge. To our knowledge, this is the first reported case of spontaneous coronary artery dissection in association with cardiac tamponade that was treated conservatively and had a successful outcome.

  13. Inwardly rotating spirals in nonuniform excitable media.

    Science.gov (United States)

    Gao, Xiang; Feng, Xia; Cai, Mei-chun; Li, Bing-wei; Ying, He-ping; Zhang, Hong

    2012-01-01

    Inwardly rotating spirals (IRSs) have attracted great attention since their observation in an oscillatory reaction-diffusion system. However, IRSs have not yet been reported in planar excitable media. In the present work we investigate rotating waves in a nonuniform excitable medium, consisting of an inner disk part surrounded by an outer ring part with different excitabilities, by numerical simulations of a simple FitzHugh-Nagumo model. Depending on the excitability of the medium as well as the inhomogeneity, we find the occurrence of IRSs, of which the excitation propagates inwardly to the geometrical spiral tip.

  14. TRIGGERED STAR FORMATION IN SPIRAL ARMS

    Directory of Open Access Journals (Sweden)

    E. E. Martínez-García

    2009-01-01

    Full Text Available We present the status of our research, relative to the triggering of star formation by large-scale galactic shocks associated with spiral density waves. Around a third of the galaxies in our sample do not seem suitable for this kind of study, because they present an e ect, probably due to opacity, that is not well understood. The remaining objects seem to favor the idea of density wave triggering of star formation in the arms. The comparison with stellar population synthesis models, and the orbital resonance positions for these galaxies (derived by means of spiral pattern angular speeds corroborate this hypothesis.

  15. Beautiful math--aesthetic patterns based on logarithmic spirals.

    Science.gov (United States)

    Xinchang Wang; Peichang Ouyang

    2013-01-01

    A simple, fast method generates various visually appealing spiral patterns. The method is based on the concept that spiral patterns comprise a symmetry group of tilings. It employs invariant mappings and a dynamical system to create seamless colored patterns.

  16. Controlling spiral wave with target wave in oscillatory systems

    Institute of Scientific and Technical Information of China (English)

    Liu Fu-Cheng; Wang Xiao-Fei; Li Xue-Chen; Dong Li-Fang

    2007-01-01

    Spiral waves have been controlled by generating target waves with a localized inhomogeneity in the oscillatory medium. The competition between the spiral waves and target waves is discussed. The effect of the localized inhomogeneity size has also been studied.

  17. Evolution of Spiral Waves under Modulated Electric Fields

    Institute of Scientific and Technical Information of China (English)

    MA Jun; YING He-Ping; PAN Guo-Wei; PU Zhong-Sheng

    2005-01-01

    @@ Spirals generated from the excitable media within the Barkley model is investigated under the gradient electric fields by a numerical simulation. The spiral drift and spiral break up are observed when the amplitude of the electric fields is modulated by a constant signal or a chaotic signal. It is also verified that, even in the presence of the white noise, the whole system can reach homogeneous states after the spiral breakup, by using an adaptive strategy.

  18. A Non-invasive Method of Tracing Spiral Tips

    Institute of Scientific and Technical Information of China (English)

    王凯; 毛晓明; 欧阳颀

    2001-01-01

    A new method is developed to trace the tip of spiral waves in an excitable medium. The information of a spiraltip movement is obtained from only six probes. This method can trace the tip of a simple rotating spiral as wellas a complex spiral tip movement. More importantly, it can be used to distinguish between a spiral and a targetwave. The method is checked with data by experiments and numerical simulations, and found to be successful.

  19. Spiral Waves in Media with Spatial Period-2 Structure

    Institute of Scientific and Technical Information of China (English)

    YANG Jun-Zhong; ZHANG Mei

    2005-01-01

    @@ The spiral waves in a system of two-dimensional coupled oscillators with spatial period-2 structure are investigated.We find a sandwiched spiral wave where any adjacent oscillators are in anti-phase. We show that the propagation rate of the sandwiched spiral wave is insensitive to the change of the coupling constant. The influences of the local kinetics on the sandwiched spiral wave are also investigated.

  20. Aortic Dissection Type A in Alpine Skiers

    Science.gov (United States)

    Schachner, Thomas; Fischler, Nikolaus; Dumfarth, Julia; Bonaros, Nikolaos; Krapf, Christoph; Schobersberger, Wolfgang; Grimm, Michael

    2013-01-01

    Patients and Methods. 140 patients with aortic dissection type A were admitted for cardiac surgery. Seventy-seven patients experienced their dissection in the winter season (from November to April). We analyzed cases of ascending aortic dissection associated with alpine skiing. Results. In 17 patients we found skiing-related aortic dissections. Skiers were taller (180 (172–200) cm versus 175 (157–191) cm, P = 0.008) and heavier (90 (68–125) kg versus 80 (45–110) kg, P = 0.002) than nonskiers. An extension of aortic dissection into the aortic arch, the descending thoracic aorta, and the abdominal aorta was found in 91%, 74%, and 69%, respectively, with no significant difference between skiers and nonskiers. Skiers experienced RCA ostium dissection requiring CABG in 17.6% while this was true for 5% of nonskiers (P = 0.086). Hospital mortality of skiers was 6% versus 13% in nonskiers (P = 0.399). The skiers live at an altitude of 170 (0–853) m.a.s.l. and experience their dissection at 1602 (1185–3105; P sport at unusual high altitude at cold temperatures. Postoperative outcome is good. PMID:23971024

  1. [A case of primary coronary artery dissection].

    Science.gov (United States)

    Nishino, M; Kato, J; Ezumi, A; Nozaki, S; Nishino, Y; Tanahashi, H; Yasuno, M; Kobayashi, K; Yamada, Y; Abe, H

    1990-06-01

    Primary coronary artery dissection occurring as a spontaneous event and not associated with trauma due to catheter manipulation is rare. We recently experienced (a case of) a 52-year-old man with primary artery dissection. He was admitted to our hospital with severe chest pain as his chief complaint on September 6, 1988. Electrocardiography and laboratory data showed acute inferior myocardial infarction. He was treated with medication and underwent coronary angiograms on October 3, 1988. Right coronary angiogram revealed an intimal flap and false lumen. But right coronary angiograms 6 months after the onset of myocardial infarction revealed progression of stenosis but no intimal flap, and coronary spasm was not evoked after acetylcholine administration. Primary coronary artery dissection has been reported since Pretty's first description of it in 1931. The majority of earlier cases were diagnosed at autopsy, but recently reports of survivors have been increasing due to the progress in and popularization of coronary angiographic technics. This case is the 46th case of primary coronary dissection found by coronary angiography. So it is not extremely rare. In our case the involved artery was the right coronary artery. In survivors, right coronary artery dissection is more frequent than left, because the area supplied by the right coronary artery is smaller than the area supplied by the left one. Although in our case coronary artery stenosis progressed, after a long term resolution of dissection may occur. There are a few cases in which resolution of dissection occurred naturally.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Short WSRT HI observations of spiral galaxies

    NARCIS (Netherlands)

    Rhee, MH; vanAlbada, TS

    1996-01-01

    We have obtained short HI observations of 60 late type spiral galaxies with the Westerbork Synthesis Radio Telescope (WSRT). Several HI properties are presented, including the radial surface density distribution of HI and a position-velocity map. When possible these are compared to those measured fr

  3. Spiral kicker for the beam abort system

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.L.

    1983-01-01

    A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost.

  4. How to make a spiral bacterium

    Science.gov (United States)

    Wolgemuth, Charles W.; Inclan, Yuki F.; Quan, Julie; Mukherjee, Sulav; Oster, George; Koehl, M. A. R.

    2005-09-01

    The motility of some kinds of bacteria depends on their spiral form, as does the virulence of certain pathogenic species. We propose a novel mechanism for the development of spiral shape in bacteria and the supercoiling of chains ('filaments') of many cells. Recently discovered actin-like proteins lying just under the cell wall form fibers that play a role in maintaining cell shape. Some species have a single actin-like fiber helically wrapped around the cell, while others have two fibers wrapped in the same direction. Here, we show that if these fibers elongate more slowly than growth lengthens the cell, the cell both twists and bends, taking on a spiral shape. We tested this mechanism using a mathematical model of expanding fiber-wound structures and via experiments that measure the shape changes of elongating physical models. Comparison of the model with in vivo experiments on stationary phase Caulobacter crescentus filaments provide the first evidence that mechanical stretching of cytoskeletal fibers influences cell morphology. Any hydraulic cylinder can spiral by this mechanism if it is reinforced by stretch-resistant fibers wrapped helically in the same direction, or shortened by contractile elements. This might be useful in the design of man-made actuators.

  5. Some optical properties of the spiral inflector

    CERN Document Server

    Toprek, D

    1999-01-01

    This paper compares some optical properties of different spiral inflectors using the program CASINO. The electric field distribution in the inflectors has been numerically calculated from an electric potential map produced by the program RELAX3D. The magnetic field is assumed to be constant. We have also made an effort to minimize the inflector fringe field using the RELAX3D program. (author)

  6. Maximum life spiral bevel reduction design

    Science.gov (United States)

    Savage, M.; Prasanna, M. G.; Coe, H. H.

    1992-07-01

    Optimization is applied to the design of a spiral bevel gear reduction for maximum life at a given size. A modified feasible directions search algorithm permits a wide variety of inequality constraints and exact design requirements to be met with low sensitivity to initial values. Gear tooth bending strength and minimum contact ratio under load are included in the active constraints. The optimal design of the spiral bevel gear reduction includes the selection of bearing and shaft proportions in addition to gear mesh parameters. System life is maximized subject to a fixed back-cone distance of the spiral bevel gear set for a specified speed ratio, shaft angle, input torque, and power. Significant parameters in the design are: the spiral angle, the pressure angle, the numbers of teeth on the pinion and gear, and the location and size of the four support bearings. Interpolated polynomials expand the discrete bearing properties and proportions into continuous variables for gradient optimization. After finding the continuous optimum, a designer can analyze near optimal designs for comparison and selection. Design examples show the influence of the bearing lives on the gear parameters in the optimal configurations. For a fixed back-cone distance, optimal designs with larger shaft angles have larger service lives.

  7. The handedness of historiated spiral columns.

    Science.gov (United States)

    Couzin, Robert

    2016-11-17

    Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.

  8. Arm Structure in Anemic Spiral Galaxies

    CERN Document Server

    Elmegreen, D M; Frogel, J A; Eskridge, P B; Pogge, R W; Gallagher, A; Iams, J; Elmegreen, Debra Meloy; Elmegreen, Bruce G.; Frogel, Jay A.; Eskridge, Paul B.; Pogge, Richard W.; Gallagher, Andrew; Iams, Joel

    2002-01-01

    Anemic galaxies have less prominent star formation than normal galaxies of the same Hubble type. Previous studies showed they are deficient in total atomic hydrogen but not in molecular hydrogen. Here we compare the combined surface densities of HI and H2 at mid-disk radii with the Kennicutt threshold for star formation. The anemic galaxies are below threshold, which explains their lack of prominent star formation, but they are not much different than other early type galaxies, which also tend to be below threshold. The spiral wave amplitudes of anemic and normal galaxies were also compared, using images in B and J passbands from the OSU Bright Spiral Galaxy Survey. Anemic galaxies have normal spiral wave properties too, with the same amplitudes and radial dependencies as other galaxies of the same arm class. Because of the lack of gas, spiral waves in early type galaxies and anemics do not have a continuous supply of stars with low velocity dispersions to maintain a marginally stable disk. As a result, they ...

  9. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  10. Colloidal spirals in nematic liquid crystals.

    Science.gov (United States)

    Senyuk, Bohdan; Pandey, Manoj B; Liu, Qingkun; Tasinkevych, Mykola; Smalyukh, Ivan I

    2015-12-07

    One of the central experimental efforts in nematic colloids research aims to explore how the interplay between the geometry of particles along with the accompanying nematic director deformations and defects around them can provide a means of guiding particle self-assembly and controlling the structure of particle-induced defects. In this work, we design, fabricate, and disperse low-symmetry colloidal particles with shapes of spirals, double spirals, and triple spirals in a nematic fluid. These spiral-shaped particles, which are controlled by varying their surface functionalization to provide tangential or perpendicular boundary conditions of the nematic molecular alignment, are found inducing director distortions and defect configurations with non-chiral or chiral symmetry. Colloidal particles also exhibit both stable and metastable multiple orientational states in the nematic host, with a large number of director configurations featuring both singular and solitonic nonsingular topological defects accompanying them, which can result in unusual forms of colloidal self-assembly. Our findings directly demonstrate how the symmetry of particle-generated director configurations can be further lowered, or not, as compared to the low point group symmetry of solid micro-inclusions, depending on the nature of induced defects while satisfying topological constraints. We show that achiral colloidal particles can cause chiral symmetry breaking of elastic distortions, which is driven by complex three-dimensional winding of induced topological line defects and solitons.

  11. Biofouling of spiral wound membrane systems

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.

    2009-01-01

    Biofouling of spiral wound membrane systems High quality drinking water can be produced with membrane filtration processes like reverse osmosis (RO) and nanofiltration (NF). Because the global demand for fresh clean water is increasing, these membrane technologies will increase in importance in the

  12. Development of phantoms for spiral CT.

    Science.gov (United States)

    Goodenough, D J; Levy, J R; Kasales, C

    1998-01-01

    This paper reports on the development of a new phantom for spiral CT. The phantom meets the increased demands on phantom z-axis uniformity in order that objects from the CT slice, immediately above and below the CT slice of interest, do not contribute perturbing information to the reconstructed CT slice. The phantom depends on formulation of tissue-like materials that can be cast and produced in both geometric and anthropomorphic shapes with sufficient z-axis length to enable unperturbed CT slices of test objects of interest. These materials are then used to produce a series of test objects of CT image quality including low contrast samples that do not require volume averaging or mixing of solutions, and that can reflect sub-slice thickness test objects and supra-slice thickness test objects. The overall phantom and its individual test objects provides meaningful tests of spiral CT image quality including slice sensitivity, CT number linearity and tests of high and low contrast resolution. Schematic designs and actual CT scans are shown. The new spiral phantom appears to meet the increased demands of spiral CT on phantom design, particularly z-axis length, and requirements for low contrast resolution test objects.

  13. The Spiral Curriculum. Research into Practice

    Science.gov (United States)

    Johnston, Howard

    2012-01-01

    The Spiral Curriculum is predicated on cognitive theory advanced by Jerome Bruner (1960), who wrote, "We begin with the hypothesis that any subject can be taught in some intellectually honest form to any child at any stage of development." In other words, even the most complex material, if properly structured and presented, can be understood by…

  14. Curved spiral antennas for underwater biological applications

    Science.gov (United States)

    Llamas, Ruben

    We developed curved spiral antennas for use in underwater (freshwater) communications. Specifically, these antennas will be integrated in so-called mussel backpacks. Backpacks are compact electronics that incorporate sensors and a small radio that operate around 300 MHz. Researchers attach these backpacks in their freshwater mussel related research. The antennas must be small, lightweight, and form-fit the mussel. Additionally, since the mussel orientation is unknown, the antennas must have broad radiation patterns. Further, the electromagnetic environment changes significantly as the mussels burrow into the river bottom. Broadband antennas, such a spiral antennas, will perform better in this instance. While spiral antennas are well established, there has been little work on their performance in freshwater. Additionally, there has been some work on curved spiral antennas, but this work focused on curving in one dimension, namely curving around a cylinder. In this thesis we develop spiral antennas that curve in two dimensions in order to conform the contour of a mussel's shell. Our research has three components, namely (a) an investigation of the relevant theoretical underpinning of spiral antennas, (b) extensive computer simulations using state-of-the art computational electromagnetics (CEM) simulation software, and (c) experimental validation. The experimental validation was performed in a large tank in a laboratory setting. We also validated some designs in a pool (~300,000 liters of water and ~410 squared-meter dive pool) with the aid of a certified diver. To use CEM software and perform successful antenna-related experiments require careful attention to many details. The mathematical description of radiation from an antenna, antenna input impedance and so on, is inherently complex. Engineers often make simplifying assumptions such as assuming no reflections, or an isotropic propagation environment, or operation in the antenna far field, and so on. This makes

  15. Development of a surface micromachined spiral-channel viscous pump

    Science.gov (United States)

    Kilani, Mohammad Ibrahim

    This work introduces a new pump, called the spiral pump, which targets the surface micromachining technology. We demonstrate the possibility of realizing the spiral pump geometry in standard surface micromachining, lay out the theoretical foundation for its operation, and conduct an objective assessment for its practicality. The spiral pump is a shear-driven viscous pump, which works by rotating a disk with a spiral groove at a close proximity over a stationary plate. Fluid contained in the spiral groove between the stationary plate and the rotating disk, is subject to a net tangential viscous stress, which allows it to be transported against an imposed pressure difference. A number of spiral pumps were fabricated in 5 levels of polysilicon using Sandia's Ultraplanar Multilevel Surface Micromachining Technology, SUMMiT, and the fabricated micropump were tested in dry-run mode using electrostatic probing and optical microscopy. To achieve a more comprehensive understanding of the spiral micropump operation, an analytical model was developed for the flow field in the spiral channel of the pump using an approximation which replaces the spiral channel with an equivalent straight channel with appropriate dimensions and boundary conditions. An analytical solution for this model at the lubrication limit relates the flow rate, torque and power consumption of the spiral pump to the pressure difference and rotation rate. The model was validated using macroscale experiments conducted on a scaled up spiral pump model, which involved a quantitative characterization of the spiral pump performance. Those experiments validate the developed theory and help assess the practicality of the spiral pump concept. In addition to the spiral pump, two positive-displacement ring-gear pumps were designed and fabricated in this work. The feasibility of surface micromachined ring-gear pumps is briefly investigated in this work, and compare to that of the spiral micropump.

  16. Spiral CT for evaluation of chest trauma; Spiral-CT beim Thoraxtrauma

    Energy Technology Data Exchange (ETDEWEB)

    Roehnert, W. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik; Weise, R. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik

    1997-07-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [Deutsch] Nach Einfuehrung der Spiral-CT in unserer Einrichtung versuchten wir, den Stellenwert der Computertomographie in der Notfalldiagnostik des Thoraxtraumas neu zu bestimmen. Dazu wurden retrospektiv ueber einen Zeitraum von 10 Monaten alle mittels Spiral-CT untersuchten Notfallpatienten mit Thoraxverletzungen ausgewertet. Im Vordergrund standen folgende Befunde unterschiedlichen Schweregrades: Pneumothorax, Haematothorax, Lungenkontusion/-lazeration, Mediastinalhaematom, Gefaessruptur, Herz- und Herzbeutelverletzung. Auf die unterschiedlichen Frakturen wird bewusst nicht naeher eingegangen. In vielen Faellen liefert die Spiral-CT mit relativ geringem Zeitaufwand wesentliche diagnostische Aussagen. Haeufig kann auf eine Angiographie verzichtet werden. Ein starres diagnostisches Stufenschema laesst sich nicht definieren. Die Thoraxuebersichtsaufnahme besitzt einen unveraendert hohen Stellenwert. (orig.)

  17. The Geometry of the Galaxy's Spiral Arms

    Science.gov (United States)

    Steiman-Cameron, Thomas Y.; Wolfire, M.; Hollenbach, D.

    2008-05-01

    We present a new model for the spiral structure of the Milky Way based upon an analysis of the essentially all-sky spectral data obtained by the Far Infrared Absolute Spectrophotometer (FIRAS) instrument of the Cosmic Background Explorer (COBE) satellite. The model provides the volume emissivities of the [C II] 128 µm and [N II] 205 µm lines, as a function of position within the Galaxy. These lines are important coolants of the interstellar medium and strong tracers of the spiral structure. Despite decades of work, there is still no full agreement on the number of spiral arms in the Milky Way, much less the details of their geometry. Motivated, in part, by this fact, we conducted a systematic search for 2-arm, 3-arm, and 4-arm models that maximize agreement with the COBE data. We find that only a four-arm model, with arms defined by logarithmic spiral forms and pitch angles ranging from 13.5 to 15.6 degrees, is consistent with the observations. The arms are neither evenly spaced nor identical in form. The resultant volume emissivity models for C+ and N+, when convolved with the FIRAS beam and integrated over the Galaxy, reproduce the COBE [C II] 128 µm and [N II] 205 µm intensity maps extremely well. We also examine all models for the Galaxy's spiral structure that have been proposed over the past half century in the context of the same COBE observations. A significant fraction of these models, including many recent ones, appear to be incompatible with the data. However, several four-arm models from the literature are consistent with the COBE observations.

  18. Safe Control for Spiral Recovery of Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Chang-Jian Ru

    2014-01-01

    Full Text Available With unmanned aerial vehicles (UAVs widely used in both military and civilian fields, many events affecting their safe flying have emerged. That UAV’s entering into the spiral is such a typical safety issue. To solve this safety problem, a novel recovery control approach is proposed. First, the factors of spiral are analyzed. Then, based on control scheduling of state variables and nonlinear dynamic inversion control laws, the spiral recovery controller is designed to accomplish guidance and control of spiral recovery. Finally, the simulation results have illustrated that the proposed control method can ensure the UAV autonomous recovery from spiral effectively.

  19. Analysis of the spiral structure in a simulated galaxy

    CERN Document Server

    Mata-Chávez, Dolores; Puerari, Ivânio

    2014-01-01

    We analyze the spiral structure that results in a numerical simulation of a galactic disk with stellar and gaseous components evolving in a potential that includes an axisymmetric halo and bulge. We perform a second simulation without the gas component to observe how it affects the spiral structure in the disk. To quantify this, we use a Fourier analysis and obtain values for the pitch angle and the velocity of the self-excited spiral pattern of the disk. The results show a tighter spiral in the simulation with gaseous component. The spiral structure is consistent with a superposition of waves, each with a constant pattern velocity in given radial ranges.

  20. Oxygen and nitrogen abundances in Virgo and field spirals

    OpenAIRE

    Pilyugin, L. S.; Molla, Mercedes; Ferrini, Federico; Vilchez, Jose M.

    2001-01-01

    The oxygen and nitrogen abundances in the HII regions of the nine Virgo spirals of the sample from Skillman et al (1996) and in nine field spiral galaxies are re-determined with the recently suggested P - method. We confirm that there is an abundance segregation in the sample of Virgo spirals in the sense that the HI deficient Virgo spirals near the core of the cluster have higher oxygen abundances in comparison to the spirals at the periphery of the Virgo cluster. At the same time both the V...

  1. Breakup of Spiral Waves in Coupled Hindmarsh-Rose Neurons

    Institute of Scientific and Technical Information of China (English)

    MA Jun; JIA Ya; TANG Jun; YANG Li-Jian

    2008-01-01

    @@ Breakup of spiral wave in the Hindmarsh-Rose neurons with nearest-neighbour couplings is reported.Appropriate initial values and parameter regions are selected to develop a stable spiral wave and then the Gauesian coloured noise with different intensities and correlation times is imposed on all neurons to study the breakup of spiral wave, respectively.Based on the mean field theory, the statistical factor of synchronization is defined to analyse the evolution of spiral wave.It is found that the stable rotating spiral wave encounters breakup with increasing intensity of Gaussian coloured noise or decreasing correlation time to certain threshold.

  2. Spiral analysis-improved clinical utility with center detection.

    Science.gov (United States)

    Wang, Hongzhi; Yu, Qiping; Kurtis, Mónica M; Floyd, Alicia G; Smith, Whitney A; Pullman, Seth L

    2008-06-30

    Spiral analysis is a computerized method that measures human motor performance from handwritten Archimedean spirals. It quantifies normal motor activity, and detects early disease as well as dysfunction in patients with movement disorders. The clinical utility of spiral analysis is based on kinematic and dynamic indices derived from the original spiral trace, which must be detected and transformed into mathematical expressions with great precision. Accurately determining the center of the spiral and reducing spurious low frequency noise caused by center selection error is important to the analysis. Handwritten spirals do not all start at the same point, even when marked on paper, and drawing artifacts are not easily filtered without distortion of the spiral data and corruption of the performance indices. In this report, we describe a method for detecting the optimal spiral center and reducing the unwanted drawing artifacts. To demonstrate overall improvement to spiral analysis, we study the impact of the optimal spiral center detection in different frequency domains separately and find that it notably improves the clinical spiral measurement accuracy in low frequency domains.

  3. Type B Aortic Dissection: Management Updates

    Directory of Open Access Journals (Sweden)

    Naghmeh Moshtaghi

    2009-12-01

    Full Text Available Acute aortic dissection (AAD is the most frequent catastrophic event of the aorta; it occurs nearly three times as frequently as the rupture of abdominal aortic aneurysm. Sixty percent of dissection cases are classified as proximal or type A and 40% as distal or type B, according to the Stanford Classification. The most frequent causes of death in acute type B dissection are aortic rupture and malperfusion syndrome.We herein review recent data suggesting different management modalities of type B aortic dissection, including medical, surgical, and endovascular treatments. Although medical therapy is still the standard approach in uncomplicated cases, there are subgroups of patients who may benefit from endovascular management. Endovascular techniques or surgery are valuable options for complicated cases. Hybrid suites, multidisciplinary approaches, and good imaging techniques can be considered as the key to success in this regard.

  4. Migraine and vertebrobasilar dissection: Case reports.

    Science.gov (United States)

    Yenari, M A; Steinberg, G K; Marks, M P

    1994-01-01

    We report two patients with chronic migraine headaches who developed vertebrobasilar arterial dissections. In both cases, there was a change in both the character and location of the headaches, which prompted further evaluation with magnetic resonance imaging and angiography, which led to the diagnosis. Other possible risk factors for dissection in these patients included hypertension, exercise, and chiropractic manipulation. Both patients were treated with anticoagulation and recovered with little to no neurologic deficit. A review of the literature relating migraine and arterial dissection suggests that there may be an association. Although more extensive controlled studies are needed to demonstrate the significance of this association, we suggest that the diagnosis of cervicocranial arterial dissection be strongly considered in migraine patients who develop an abrupt change in the nature of their headaches. Copyright © 1994 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  5. Cervical artery dissection following a turbulent flight.

    LENUS (Irish Health Repository)

    Quinn, Colin

    2012-01-31

    BACKGROUND: Cervical artery dissection is a common cause of stroke in young patients without vascular risk factors and may affect the carotid or vertebral arteries. The risk of spontaneous dissection is higher in those with genetic predisposing factors while other cases may be precipitated by an event involving head or neck movement or associated with direct neck trauma. CASE REPORT: We present the case of a previously well young woman with a history of migraine who developed internal carotid artery dissection following a turbulent short-haul commercial flight while restrained using a seatbelt. DISCUSSION: We propose that repetitive flexion-hyperextension neck movements encountered during the flight were the most likely precipitant of carotid artery dissection in this case and review the therapeutic options available.

  6. Laparoscopic anatomy and dissection of the pelvis.

    Science.gov (United States)

    Kadar, N

    1997-03-01

    All anatomically important pelvic structures lie embedded in the fatty-fibrous connective tissue of the retroperitoneum from which they can be freed by blunt dissection in the correct tissue planes. By relying on fixed laparoscopic landmarks, the correct surgical planes of dissection can be found, and all vital structures freed and identified by a systematic dissection consisting of a precise sequence of operative steps. Once the retroperitoneal dissection has been completed and all vital structures identified, most gynaecological operations can be carried out safely and without much difficulty laparoscopically. A non-anatomical approach to laparoscopic pelvic surgery may be easier to learn, but it is neither very versatile nor very safe except in the simplest of cases.

  7. Dissecting aortic aneurysm in maintenance hemodialysis patients

    Directory of Open Access Journals (Sweden)

    Ounissi M

    2009-01-01

    Full Text Available The dissecting aortic aneurysm (DAA is a rare pathology that may result in fatal outcome. We report follow up of three cases of DAA patients undergoing maintenance hemo-dialysis who were managed conservatively.

  8. Extended lymph node dissection for prostate cancer.

    Science.gov (United States)

    Jeschke, Stephan; Burkhard, Fiona C; Thurairaja, Ramesh; Dhar, Nivedita; Studer, Urs E

    2008-05-01

    Lymph node status is an important determinant for the management of patients with newly diagnosed prostate cancer. Given the significant limitations of cross-sectional and functional preoperative imaging in the detection of small metastases, pelvic lymph node dissection remains the only reliable staging method in clinically localized prostate cancer. Although lymph node dissection is a well-established form of staging in prostate cancer, controversy remains about indications and the surgical extent of the procedure. Reported practices vary from omitting pelvic lymph node dissection in low-risk disease to routine pelvic lymph node dissection in all radical prostatectomy patients. This review highlights the recent literature concerning pelvic lymphadenectomy in prostate cancer with respect to anatomical extent and oncologic outcome.

  9. Animal Rights Groups Target High School Dissection.

    Science.gov (United States)

    Trotter, Andrew

    1992-01-01

    Two groups leading the charge against dissection are People for the Ethical Treatment of Animals (PETA) and the Student Action Corps for Animals (SACA). Protests by student and community members remain the movement's strongest weapon. (MLF)

  10. [Gross anatomy dissection and the legal control].

    Science.gov (United States)

    Yamashina, Shohei; Shibata, Yosaburo

    2010-12-01

    In Japan, dissection of human body is generally prohibited by the Penal Code, i.e. the criminal law. However, the Postmortem Examination and Corpse Preservation Act allows for the dissection of the body in very limited situations, that include gross anatomy dissection and pathological and forensic autopsy in medical and dental schools. Growing numbers of co-medical schools have been founded more recently in Japan, and not a small number of co-medical schools try to adopt human body dissection in the course of anatomy education. The present short communication reminds us of the ways of thinking of the Postmortem Examination and Corpse Preservation Act and the Act on Body Donation for Medical and Dental Education in order that anatomy education in medical as well as co-medical schools takes place under the regulation by these two laws.

  11. The formation of molecular clouds in spiral galaxies

    CERN Document Server

    Dobbs, C L

    2006-01-01

    We present Smoothed Particle Hydrodynamics (SPH) simulations of molecular cloud formation in spiral galaxies. These simulations model the response of a non-self-gravitating gaseous disk to a galactic potential. The formation of molecular gas occurs when cold ($T \\le 100$ K) gas is compressed during the passage of a spiral arm. The spiral arms display considerable structure and the molecular gas accumulates into dense clouds. We identify the formation of these structures as due to the dynamics of clumpy shocks, which perturb the orbits of particles passing through the spiral arm. In addition, the spiral shocks induce a large velocity dispersion in the spiral arms, comparable with the magnitude of the velocity dispersion observed in molecular clouds. The molecular clouds are largely confined to the spiral arms, since most molecular gas is photodissociated to atomic hydrogen upon leaving the arms. However a low photodissociation rate increases the amount of interarm molecular gas, and the possibility of molecula...

  12. Assessment of spiral CT pneumocolon in preoperative colorectal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Can-Hui Sun; Zi-Ping Li; Quan-Fei Meng; Shen-Ping Yu; Da-Sheng Xu

    2005-01-01

    AIM: To investigate the value of spiral CT pneumocolon in preoperative colorectal carcinoma.METHODS: Spiral CT pneumocolon was performed prior to surgery in 64 patients with colorectal carcinoma. Spiral CT images were compared to specimens from the resected tumor.RESULTS: Spiral CT depicted the tumor in all patients.Comparison of spiral CT and histologic results showed that the sensitivity and specificity were 95.2%, 40.9% in detection of local invasion, and 75.0%, 90.9% in detection of lymph node metastasis. Compared to the Dukes classification,the disease was correctly staged as A in 6 of 18 patients,as B in 18 of 23, as C in 10 of 15, and as D in 7 of 8. Overall,spiral CT correctly staged 64.1% of patients.CONCLUSION: Spiral CT pneumocolon may be useful in the preoperative assessment of patients with colorectal carcinoma as a means for assisting surgical planning.

  13. Aortic Dissection Cases Presenting with Neurological Deficit

    Directory of Open Access Journals (Sweden)

    Sibel Mumcu

    2014-06-01

    Full Text Available Aortic dissection can be fatal in case of underdiagnosis, and early treatment is essential for the survival. Although acute onset of chest or back pain is most common presenting symptoms, some patients might present with atypical findings such as acute stroke, mesenteric ischaemia, renal failure or myocardial infarction. Here, we report two cases presenting emergency room with atypical findings of aortic dissection which diagnosis is made during etiologic work up for ischemic stroke.

  14. Evaluating dissection in the gross anatomy course: Correlation between quality of laboratory dissection and students outcomes.

    Science.gov (United States)

    Nwachukwu, Chika; Lachman, Nirusha; Pawlina, Wojciech

    2015-01-01

    Anatomy learned by active exploration through dissection has many proven benefits including improvement of anatomic knowledge. Decreased laboratory time may affect the quality of dissection and ultimately lower student performance in anatomy translating to lower knowledge acquisition. The aim of this study was to determine whether the quality of students' dissection in teams correlates with their performance in the gross anatomy course. Quality of dissections for each team enrolled in a gross anatomy course at Mayo Medical School was evaluated biweekly using a five-point rubric based on course learning objectives. Assessment of anatomic knowledge was based on sequential laboratory practice practical examination scores, achievements on daily audience response system (ARS) quizzes, and final practical, written, and National Board of Medical Examiners(®) (NBME(®) ) Gross Anatomy and Embryology Subject Examinations. Twelve teams comprising 48 students were included in the study. There was a positive correlation between dissection quality and practice practical examination score (R = 0.83) and a negative correlation between dissection quality and ARS quizzes (R = -0.985). Dissection teams with a passing score on their dissection evaluations (>70%) performed better on their final examinations. Based on an end of course survey, students agreed that dissection evaluations should continue to be a part of the course. This study showed that better quality of dissection was associated with higher scores on practice practical examinations, final practical, written, and NBME examinations. The study demonstrated a positive correlation between dissection evaluations, accompanied by formative feedback during the course, and higher scores on final course assessments.

  15. The clinical application of multi-slice spiral CT angiography in abdominal aortic disease

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Objective: To evaluate the clinical application of multi-slice spiral CT angiography(MSCTA) in the assessment of abdominal aortic disease. Methods: Fifty-four patients underwent multi-slice spiral CT angiography of abdomen. Contrast agent (Omnipaque 300 I g/L) 1.5 ml/kg was injected and the injection rate was 3 ml/s. The delay time was determined by bolus tracking technique,Tll level abdominal aorta was set as the target vessel and the threshold was 180-200 Hu, slice width was 3 mm and with a pitch of 4-6.Original data were transferred to working-station to perform functional reconstruction. Results: Ten cases were normal, twenty-eight cases were abdominal aortic aneurysms, five abdominal aortic dissecting aneurysms (Debakay type Ⅲ ) and eleven aortic sclerosis. SSD showed the body of aneurysm and the relationship between aneurysm and adjacent blood vessel, MIP better displayed calcification of blood vessel wall and condition of the stent, MPR demonstrated true and false lumen, rupture site of abdominal aorta intima and mural thrombus. Conclusion: MSCTA axial and reconstruction image can show the extent of abdominal aortic disease and the relationship with adjacent blood vessels. It is a safe, simple and non-invasive examination method.

  16. Status of the SPIRAL2 injector commissioning

    Energy Technology Data Exchange (ETDEWEB)

    Thuillier, T., E-mail: thuillier@lpsc.in2p3.fr; Angot, J.; Jacob, J.; Lamy, T.; Sole, P. [LPSC, Université Grenoble Alpes, CNRS/IN2P3, 53 rue des Martyrs, 38026 Grenoble Cedex (France); Barué, C.; Bertrand, P.; Canet, C.; Ferdinand, R.; Flambard, J.-L.; Jardin, P.; Lemagnen, F.; Maunoury, L.; Osmond, B. [GANIL, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, 14076 Caen Cedex 5 (France); Biarrotte, J. L. [IPN Orsay, Université Paris Sud, CNRS/IN2P3, 15 rue Georges Clémenceau, 91406 Orsay Cedex (France); Denis, J.-F.; Roger, A.; Touzery, R.; Tuske, O.; Uriot, D. [Irfu, CEA Saclay, DSM/Irfu/SACM, 91191 Gif Sur Yvette (France); and others

    2016-02-15

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.

  17. Discontinuous Spirals of Stable Periodic Oscillations

    DEFF Research Database (Denmark)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase...... orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy...... specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization...

  18. Modes Of The Spiral Clock Gong

    Science.gov (United States)

    Perrin, R.; Charnley, T.; Swallowe, G. M.; Banu, H.

    1993-03-01

    The modal frequencies of a spiral clock gong have been measured. The mode numbers and forms of vibrations have been identified by finite element modelling and photographic techniques; very good agreement between modelling and experiment was achieved. All modes were found to be either purely in-plane or out-of-plane. In both cases plots of log (2 n - 1) vs. log ƒ yielded curves with two distinct regions, the transition occurring where the wavelength corresponded to one turn of the spiral. Both sets of lower modes were very complex but the modal frequencies above n = 11 were found to fit a modified form of Chladni's law. It is suggested that the modified Chladni law may form the basis of many musical sounds.

  19. Spiral precipitation patterns in confined chemical gardens.

    Science.gov (United States)

    Haudin, Florence; Cartwright, Julyan H E; Brau, Fabian; De Wit, A

    2014-12-09

    Chemical gardens are mineral aggregates that grow in three dimensions with plant-like forms and share properties with self-assembled structures like nanoscale tubes, brinicles, or chimneys at hydrothermal vents. The analysis of their shapes remains a challenge, as their growth is influenced by osmosis, buoyancy, and reaction-diffusion processes. Here we show that chemical gardens grown by injection of one reactant into the other in confined conditions feature a wealth of new patterns including spirals, flowers, and filaments. The confinement decreases the influence of buoyancy, reduces the spatial degrees of freedom, and allows analysis of the patterns by tools classically used to analyze 2D patterns. Injection moreover allows the study in controlled conditions of the effects of variable concentrations on the selected morphology. We illustrate these innovative aspects by characterizing quantitatively, with a simple geometrical model, a new class of self-similar logarithmic spirals observed in a large zone of the parameter space.

  20. Spiral holographic imaging through quantum interference

    Science.gov (United States)

    Tang, Jie; Ming, Yang; Hu, Wei; Lu, Yan-qing

    2017-07-01

    Spiral holographic imaging in the Hong-Ou-Mandel interference scheme is introduced. Using spontaneous parametric down-conversion as a source of photon pairs, we analyze the joint orbital angular momentum spectrum of a reference photon and the photon encoding information of the object. The first-order interference of light beams in standard holographic imaging is replaced by the quantum interference of two-photon probability amplitudes. The difficulty in retrieving the amplitude and phase structure of an unknown photon is thereby avoided as classical interferometric techniques such as optical holography do not apply. Our results show that the full information of the object's transmission function can be recorded in the spiral hologram, which originates directly from the joint orbital angular momentum spectrum. This presents a lateral demonstration of compressive imaging and can potentially be used for remote sensing.

  1. Status of the SPIRAL2 injector commissioning

    Science.gov (United States)

    Thuillier, T.; Angot, J.; Barué, C.; Bertrand, P.; Biarrotte, J. L.; Canet, C.; Denis, J.-F.; Ferdinand, R.; Flambard, J.-L.; Jacob, J.; Jardin, P.; Lamy, T.; Lemagnen, F.; Maunoury, L.; Osmond, B.; Peaucelle, C.; Roger, A.; Sole, P.; Touzery, R.; Tuske, O.; Uriot, D.

    2016-02-01

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ˜50. A status of its assembly is proposed.

  2. Modelling Neutral Hydrogen Discs of Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    林伟鹏; 洪碧海

    2002-01-01

    We present an analytical model of a neutral hydrogen disc in a spiral galaxy. The gas disc of the spiral galaxy isassumed to have an exponential surface density profile and to be ionized by the cosmic ultraviolet background.To compare with observations, we consider the disc position angle and inclination angle for a line of sight goingthrough the galaxy disc. The HI column densities depend on the strength of ionizing field and disc position andinclination. The model was applied to NGC 3198 and the results were compared with observational data. TheHI disc profile at large disc radii can be tested by further HI observations using radio telescopes with a largeraperture than the present facilities. This HI disc model can be used to predict quasar absorption line systems bygalaxy discs if quasar lines of sight go through the discs.

  3. Understanding the transformation of spirals to lenticulars

    CERN Document Server

    Johnston, Evelyn J; Merrifield, Michael R

    2014-01-01

    By studying the individual star-formation histories of the bulges and discs of lenticular (S0) galaxies, it is possible to build up a sequence of events that leads to the cessation of star formation and the consequent transformation from the progenitor spiral. In order to separate the bulge and disc stellar populations, we spectroscopically decomposed long-slit spectra of Virgo Cluster S0s into bulge and disc components. Analysis of the decomposed spectra shows that the most recent star formation activity in these galaxies occurred within the bulge regions, having been fuelled by residual gas from the disc. These results point towards a scenario where the star formation in the discs of spiral galaxies are quenched, followed by a final episode of star formation in the central regions from the gas that has been funnelled inwards through the disc.

  4. Determining the Co-Rotation Radius of Nearby Spiral Galaxies Using Spiral Arm Overlays

    Science.gov (United States)

    Shameer Abdeen, Mohamed; Kennefick, Daniel; Kennefick, Julia D.; Pour Imani, Hamed; Shields, Douglas W.; Eufrasio, Rafael; Berlanga Medina, Jazmin; Monson, Erik

    2017-01-01

    Density wave theory, originally proposed by C.C. Lin and Frank Shu (Lin & Shu 1964), views the spiral arm structures in spiral galaxies as density waves that propagates through the galactic disk. Resonances within orbits create standing wave patterns of density waves that we observe as spiral arms. The theory predicts the existence of a radius known as the co-rotation radius in which the spiral arm pattern speed matches the velocities of the stars within the disk. We introduce a novel way of determining the co-rotation radius, based on an image overlaying technique, which involves tracing the arms of spiral galaxies on images observed from different wavelengths. For the purpose of this study, 12 nearby galaxies were analyzed from four different wavelengths using pitch angle measurements from a previous study (Hamed et al. 2016). We used optical wavelength images (B-Band,440 nm), two infrared wavelength (Infrared; 3.6 µm and 8 µm) Spitzer Space Telescope images and ultraviolet images from GALEX. The results were verified by checking against results compiled from the literature.

  5. Self-Destructing Spiral Waves: Global Simulations of a Spiral Wave Instability in Accretion Disks

    CERN Document Server

    Bae, Jaehan; Hartmann, Lee; Richard, Samuel

    2016-01-01

    We present results from a suite of three-dimensional global hydrodynamic simulations which show that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break-down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport, and vertical mixing, at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter $\\alpha \\sim 5 \\times 10^{-4}$ in our reference model). The instability is found to operate in a wide-range of ...

  6. Mathematical Modeling of Spiral Heat Exchanger

    OpenAIRE

    Probal Guha , Vaishnavi Unde

    2014-01-01

    Compact Heat Exchangers (CHEs) are increasingly being used on small and medium scale industries. Due to their compact size and efficient design, they facilitate more efficient heat transfer. Better heat transfer would imply lesser fuel consumption for the operations of the plant, giving improvement to overall efficiency. This reduction in consumption of fuel is a step towards sustainable development. This report exclusively deals with the study the spiral heat ...

  7. A spiral antenna sandwiched by dielectric layers

    OpenAIRE

    Nakano, Hisamatsu; Ikeda, Masakazu; Hitosugi, Kazuo; Yamauchi, Junji

    2004-01-01

    An infinitesimally thin spiral antenna, sandwiched by bottom and top dielectric layers having the same relative permittivity, is analyzed under the condition that the dielectric layers are of finite extent and the antenna is backed by an infinite conducting plane. As the thickness of the top dielectric layer increases, the input impedance and axial ratio (AR) vary in an oscillatory fashion, with a period slightly larger than one-half of the guided wavelength of a wave propagating in an unboun...

  8. Spiral inflation with Coleman-Weinberg potential

    Science.gov (United States)

    Barenboim, Gabriela; Park, Wan-Il

    2015-03-01

    We apply the idea of spiral inflation to the Coleman-Weinberg potential and show that inflation matching our observations well is allowed for a symmetry-breaking scale ranging from an intermediate scale to a grand unified theory (GUT) scale even if the quartic coupling λ is of O (0.1 ). The tensor-to-scalar ratio can be of O (0.01 ) in the case of GUT-scale symmetry breaking.

  9. Spiral rainband in a numerically simulated tropical cyclone

    Institute of Scientific and Technical Information of China (English)

    ZHU Peijun; ZHENG Yongguang; WANG Hongqing; TAO Zuyu

    2005-01-01

    Spiral rainband is a prominent structure of tropical cyclone. Though its forming mechanism, vortex Rossby wave theory, has been widely recent in recent years, its internal structural features are still not well known. The spiral rainband in the severe tropical storm Kammuri (2002), which caused heavy rainfall in southeast China, is simulated using the mesoscale model MM5 (V3). Results show that the simulated spiral rainband propagates azimuthally at a speed close to that of vortex Rossby wave in theory, and is accom- panied with energy dispersion in the radial direction. The structural features of simulated spiral rainband are analyzed with the high-resolution model output including the full physical process. Positive vorticity, ascending motion, hori- zontal momentum and so on are highly concentrated in the spiral rainband. The convergent moisture of spiral rainband comes mostly from the planetary boundary layer under 1 km. Airflow from the outside of spiral rainband is convective instability, which can provide instability energy for convec- tion development. However, the atmospheric stratification in the inside of spiral rainband is neutral, implying that the instability energy has been released. There is a mesoscale strong wind band just near the spiral rainband in the outer side with a maximum wind speed exceeding 30 m/s, which results from the pressure force acceleration when the air flows into the spiral rainband along the gradient of pressure.

  10. Multiarm spirals in a two-dimensional cardiac substrate.

    Science.gov (United States)

    Bursac, Nenad; Aguel, Felipe; Tung, Leslie

    2004-10-26

    A variety of chemical and biological nonlinear excitable media, including heart tissue, can support stable, self-organized waves of activity in a form of rotating single-arm spirals. In particular, heart tissue can support stationary and meandering spirals of electrical excitation, which have been shown to underlie different forms of cardiac arrhythmias. In contrast to single-arm spirals, stable multiarm spirals (multiple spiral waves that rotate in the same direction around a common organizing center) have not been demonstrated and studied yet in living excitable tissues. Here, we show that persistent multiarm spirals of electrical activity can be induced in monolayer cultures of neonatal rat heart cells by a short, rapid train of electrical point stimuli applied during single-arm-spiral activity. Stable formation is accomplished only in monolayers that show a relatively broad and steep dependence of impulse wavelength and propagation velocity on rate of excitation. The resulting multiarm spirals emit waves of electrical activity at rates faster than for single-arm spirals and exhibit two distinct behaviors, namely "arm-switching" and "tip-switching." The phenomenon of rate acceleration due to an increase in the number of spiral arms possibly may underlie the acceleration of functional reentrant tachycardias paced by a clinician or an antitachycardia device.

  11. Characteristics of Left-Right Spiral Hollow Cylindrical Roller

    Institute of Scientific and Technical Information of China (English)

    Liming Lu; Qiping Chen; Yujiang Qin

    2015-01-01

    Based on new rolling⁃sliding compound bearings, the wear between the one⁃way spiral hollow cylindrical roller and the ribs of the inner and outer ring of rolling⁃sliding compound bearings is reduced by innovational structural design. A new left⁃right spiral hollow cylindrical roller is proposed to replace the one⁃way spiral hollow cylindrical roller. The finite element analysis models of ordinary cylindrical rollers, one⁃way spiral hollow cylindrical rollers and left⁃right spiral hollow cylindrical rollers are respectively established by ABAQUS. The axial displacement of their center mass and the stress distribution of left⁃right spiral hollow cylindrical rollers are compared and analyzed. Theoretical study results show that this new left⁃right spiral hollow cylindrical roller not only inherits the advantages of one⁃way spiral hollow cylindrical rollers, but also avoids the axial offset and the serious wear of the one⁃way spiral hollow cylindrical roller. And the theory research conclusion is verified by the experiment. The left⁃right spiral hollow cylindrical roller has the advantages to overcome boundary stress concentration like logarithmic convex roller. The rolling⁃sliding compound bearings equipped with the new rollers can be better to adapt to the impact of vibration load.

  12. The Milky Way and other spiral galaxies

    Directory of Open Access Journals (Sweden)

    Wang J.L.

    2012-02-01

    Full Text Available Cosmologists have often considered the Milky Way as a typical spiral galaxy, and its properties have considerably influenced the current scheme of galaxy formation. Here we compare the general properties of the Milky Way disk and halo with those of galaxies selected from the SDSS. Assuming the recent measurements of its circular velocity results in the Milky Way being offset by ~2σ from the fundamental scaling relations. On the basis of their location in the (MK, Rd, Vflat volume, the fraction of SDSS spirals like the MilkyWay is only 1.2% in sharp contrast with M31, which appears to be quite typical. Comparison of the Milky Way with M31 and with other spirals is also discussed to investigate whether or not there is a fundamental discrepancy between their mass assembly histories. Possibly the Milky Way is one of the very few local galaxies that could be a direct descendant of very distant, z = 2-3 galaxies, thanks to its quiescent history since thick disk formation.

  13. Are spiral galaxies optically thin or thick?

    CERN Document Server

    Xilouris, E M; Kylafis, N D; Paleologou, E V; Papamastorakis, J

    1999-01-01

    The opacity of spiral galaxies is examined by modelling the dust and stellar content of individual galaxies. The model is applied to five late-type spiral galaxies (NGC 4013, IC 2531, UGC 1082, NGC 5529 and NGC 5907). Having analyzed a total of seven galaxies thus far, the five galaxies mentioned above plus UGC 2048 and NGC 891 presented in (Xilouris et al. 1997, 1998), we are able to draw some general conclusions, the most significant of which are: 1) The face-on central optical depth is less than one in all optical bands indicating that typical spiral galaxies like the ones that we have modelled would be completely transparent if they were to be seen face-on. 2) The dust scaleheight is about half that of the stars, which means that the dust is more concentrated near the plane of the disk. 3) The dust scalelength is about 1.4 times larger than that of the stars and the dust is more radially extended than the stars. 4) The dust mass is found to be about an order of a magnitude more than previously measured us...

  14. Spiraling Fermi arcs in Weyl materials

    Science.gov (United States)

    Li, Songci; Andreev, Anton

    In Weyl materials the valence and conduction electron bands touch at an even number of isolated points in the Brillouin zone. In the vicinity of these points the electron dispersion is linear and may be described by the massless Dirac equation. This results in nontrivial topology of Berry connection curvature. One of its consequences is the existence of peculiar surface electron states whose Fermi surfaces form arcs connecting projections of the Weyl points onto the surface plane. Band bending near the boundary of the crystal also produces surface states. We show that in Weyl materials band bending near the crystal surface gives rise to spiral structure of energy surfaces of arc states. The corresponding Fermi surface has the shape of a spiral that winds about the projection of the Weyl point onto the surface plane. The direction of the winding is determined by the helicity of the Weyl point and the sign of the band bending potential. For close valleys arc state morphology may be understood in terms of avoided crossing of oppositely winding spirals. This work is supported by the U.S. Department of Energy Office of Science, Basic Energy Sciences under Award Number DE-FG02-07ER46452.

  15. Spiral waves in accretion discs - observations

    CERN Document Server

    Steeghs, D

    2000-01-01

    I review the observational evidence for spiral structure in the accretion discs of cataclysmic variables (CVs). Doppler tomography is ideally suited to resolve and map such co-rotating patterns and allows a straightforward comparison with theory. The dwarf nova IP Pegasi presents the best studied case, carrying two spiral arms in a wide range of emission lines throughout its outbursts. Both arms appear at the locations where tidally driven spiral waves are expected, with the arm closest to the gas stream weaker in the lines compared to the arm closest to the companion. Eclipse data indicates sub-Keplerian velocities in the outer disc. The dramatic disc structure changes in dwarf novae on timescales of days to weeks, provide unique opportunities for our understanding of angular momentum transport and the role of density waves on the structure of accretion discs. I present an extension to the Doppler tomography technique that relaxes one of the basic assumptions of tomography, and is able to map modulated emiss...

  16. Science Teachers and the Dissection Debate: Perspectives on Animal Dissection and Alternatives

    Science.gov (United States)

    Oakley, Jan

    2012-01-01

    This study investigated Ontario science and biology teachers' practices and attitudes toward animal dissection and dissection alternatives. The data was collected through a mixed methods approach involving online surveys (n = 153) and subsequent telephone interviews (n = 9) with secondary school science and biology teachers. The findings indicate…

  17. Spiral Galaxies - classical description of spiral arms and rotational velocity pattern - toy model

    CERN Document Server

    Lobodzinski, Bogdan

    2014-01-01

    We propose an explanation of features of spiral galaxies: spiral arms and observed flat rotation curves, without the presence of an exotic form of matter. The formalism is based on Boltzmanns transport equation for the collisional matter and the very-low-velocity post-Newtonian approximation of the general relativity equations expressed in the Maxwell-like form. The Maxwell-like formulation provides the base for the explanation of the above phenomena in the language of dynamically created gravitoelectromagnetic fields by the movement of mass streams in the plane of the galaxy disc. In the model we use radical simplifications expressed as neglect of the gravitational interaction between neighbors and approximation of the incompressible mass flow. In this frame we show that if the galaxy is fuelled constantly by mass from an external gas reservoir, then the amplification of the gravitomagnetic field can be large enough to create the rotational velocity pattern and spiral arms without the necessity of introducin...

  18. Identification and Management of Iatrogenic Aortocoronary Dissection

    Directory of Open Access Journals (Sweden)

    Shao-Ping Nie, MD, PhD, FESC, FSCAI

    2016-05-01

    Full Text Available Iatrogenic aortocoronary dissection (IACD is a rare but potentially life-threatening complication during coronary catheterizations. Although the incidence was relatively low, the dissection often leads to procedure failure with increased risk of myocardial infarction and death. IACD is mainly caused by disruption of intima at the ostia of left or right coronary artery during interventional procedures, and appears as luminal filling defects or persistence of contrast (“extraluminal cap” or intimal tear outside the coronary lumen. Dissection could disseminate antegradely and lead to subtotal or total occlusion of the coronary lumen. Similarly, it could extend retrogradely into the sinus of Valsalva and cusp, or even the ascending aorta, aortic arch, or descending aorta, leading to hemodynamic collapse. Early identification and prompt management is crucial to the prognosis of patients with IACD. Immediate bail-out stenting should be performed as rapidly as possible in most cases of severe dissection, even when significant propagation has already occurred. Surgery should only be considered when stenting failed to seal the dissection and the patients had hemodynamic compromise.

  19. Painless aortic dissection presenting as paraplegia.

    Science.gov (United States)

    Colak, Necmettin; Nazli, Yunus; Alpay, Mehmet Fatih; Akkaya, Ismail Olgun; Cakir, Omer

    2012-01-01

    Acute dissection of the aorta can be life-threatening. As a presenting manifestation of aortic dissection, neurologic complications such as paraplegia are rare. Herein, we report the case of a 51-year-old man who presented with sudden-onset paraplegia and ischemia of the legs, with no chest or back pain. His medical history included coronary artery bypass grafting. Physical examination revealed pulseless lower extremities, and computed tomography showed aortic dissection from the ascending aorta to the common iliac arteries bilaterally. A lumbar catheter was inserted for cerebrospinal fluid drainage, and axillary arterial cannulation was established. With the use of cardiopulmonary bypass, the aortic dissection was corrected, and the previous coronary artery grafts were reattached. The surgery restored spinal and lower-extremity perfusion, and the patient walked unaided from the hospital upon his discharge 5 days later. Although acute aortic dissection presenting as paraplegia is rare, it should be considered in patients who have pulseless femoral arteries bilaterally and sudden-onset paraplegia, despite no pain in the chest or back. Prompt diagnosis and intervention can prevent morbidity and death.

  20. The development of a retroperitoneal dissection model.

    Science.gov (United States)

    Yousuf, Aisha A; Frecker, Helena; Satkunaratnam, Abheha; Shore, Eliane M

    2017-10-01

    Knowledge of ureteric anatomy is essential for ureteric injury prevention in laparoscopic gynecologic surgery. Rates of injury increase with limited surgical experience and reduced surgical volume. Currently, there are no low-fidelity or high-fidelity simulation models for teaching and practicing ureteric dissection. Our goal was to design a laparoscopic simulation model for retroperitoneal anatomy with high face validity that is low-cost and easily reproducible. A low-fidelity 3-dimensional simulation model was developed that represents key anatomic structures encountered during retroperitoneal dissection and ureteric identification. Materials, construction steps, and costs were determined. The models were trialed by expert laparoscopic surgeons. Demographic information that included age, gender, surgical experience, and complex laparoscopic case volumes was collected. Face validity was assessed with a 5-item Likert-scale. The total cost of 1 model ranged from $65 to $75. The majority of the materials that were used were reusable, except for 2 components that cost dissection (n=7; 100%), for assessing a learner's ability before performing in the operating room (n=6; 86%), was low-cost (n=7; 100%), and was easily reproducible (n=6; 86%). This unique model fills a gap in laparoscopic simulation training. No other low- or high-fidelity models for laparoscopic retroperitoneal ureteric dissection have been identified in the literature. This simulation model is low-cost, easily reproducible, closely resembles retroperitoneal dissection during laparoscopic gynecologic surgery, and can be used for education and assessment. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Spiral Density Waves in a Young Protoplanetary Disk

    CERN Document Server

    Pérez, Laura M; Andrews, Sean M; Ricci, Luca; Isella, Andrea; Linz, Hendrik; Sargent, Anneila I; Wilner, David J; Henning, Thomas; Deller, Adam T; Chandler, Claire J; Dullemond, Cornelis P; Lazio, Joseph; Menten, Karl M; Corder, Stuartt A; Storm, Shaye; Testi, Leonardo; Tazzari, Marco; Kwon, Woojin; Calvet, Nuria; Greaves, Jane S; Harris, Robert J; Mundy, Lee G

    2016-01-01

    Gravitational forces are expected to excite spiral density waves in protoplanetary disks, disks of gas and dust orbiting young stars. However, previous observations that showed spiral structure were not able to probe disk midplanes, where most of the mass is concentrated and where planet formation takes place. Using the Atacama Large Millimeter/submillimeter Array we detected a pair of trailing symmetric spiral arms in the protoplanetary disk surrounding the young star Elias 2-27. The arms extend to the disk outer regions and can be traced down to the midplane. These millimeter-wave observations also reveal an emission gap closer to the star than the spiral arms. We argue that the observed spirals trace shocks of spiral density waves in the midplane of this young disk.

  2. Self-Perpetuating Spiral Arms in Disk Galaxies

    CERN Document Server

    D'Onghia, Elena; Hernquist, Lars

    2012-01-01

    The precise nature of spiral structure in galaxies remains uncertain. Recent studies suggest that spiral arms result from interactions between disks and satellite galaxies. Instead, leaving aside the grand bisymmetric spirals, here we consider the possibility that the multi-armed spiral features originate from density inhomogeneities orbiting within disks. Using high-resolution N-body simulations, we follow the motions of stars under the influence of gravity, and show that mass concentrations with properties similar to those of giant molecular clouds can induce the development of spiral arms through a process termed swing amplification. However, unlike in earlier work, we demonstrate that the eventual response of the disk can be highly non-linear, significantly modifying the formation and longevity of the resulting patterns. Contrary to expectations, ragged spiral structures can survive at least in a statistical sense long after the original perturbing influence has been removed. Our findings thus motivate a ...

  3. Acute headache and persistent headache attributed to cervical artery dissection

    DEFF Research Database (Denmark)

    Schytz, Henrik W; Ashina, Messoud; Magyari, Melinda

    2014-01-01

    The criteria for headache attributed to cervical artery dissection have been changed in the new third edition of the International Classification of Headache Disorders (ICHD-III beta). We have retrospectively investigated 19 patients diagnosed from 2001 to 2006 with cervical artery dissection...... at onset and followed them up six months after dissection. At dissection onset 17/19 patients were classified as headache probably attributed to vascular disorder at the time of dissection using the ICHD second edition (ICHD-II) criteria. In contrast, 17/19 of patients fulfilled the ICHD-III beta criteria...... for Headache or facial or neck pain attributed to cervical carotid or vertebral artery dissection or Headache attributed to intracranial arterial dissection. Six months after dissection five of 19 patients still reported persistent headache attributed to dissection. The study demonstrates that the ICHD...

  4. Spiral: a new equipment for exotic nuclei; Spiral: un nouvel equipement pour les noyaux exotiques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    This document presents the GANIL activities and more specially the SPIRAL project. The missions of the GANIL are to allow scientists fundamental researches in Nuclear Physics and to develop applications for heavy ions in other domains. Spiral is an european project, decided by NuPECC (NUclear Physics European Collaboration Committee). It is a first generation equipment allowing the production and the acceleration of light and moderately heavy nuclei at energy range of 2 to 25 MeV/nucleus. (A.L.B.)

  5. Nonlinear dynamics of breathers in the spiral structures of magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, V. V., E-mail: kiselev@imp.uran.ru; Raskovalov, A. A. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-06-15

    The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of “precursors” and “tails” in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.

  6. The lacet: A new type of the spiral wave behavior

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, Andrey V. [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation)], E-mail: cardio@avmoskalenko.ru; Elkin, Yury E. [Institute of Mathematical Problems of Biology, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation) and Moscow State University, Pushchino Branch, 142290 Pushchino, Moscow Region (Russian Federation)

    2009-04-15

    We found a new type of spiral wave behavior in a homogeneous two-dimensional autowave medium. In this regime, the spiral wave tip motion transforms from a two-periodic meander into one-periodic circular rotation due to spontaneous deceleration of spiral wave drift. This discovery might be useful for insight into the nature of various phenomena and, in particular, some potentially life-threatening cardiac arrhythmias.

  7. Topological Constraints on Scroll and Spiral Waves in Excitable Media

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong; HU Bambi; LI Bing-Wei; DUAN Yi-Shi

    2007-01-01

    A conservation equation for topological charges of phase singularities (scroll and spiral waves) in excitable media is given. It provides some topological properties of scroll (spiral) waves: for example, the topological charge of the generated or annihilated spiral pair must be opposite. Additionally, we obtain another equation on scroll waves, which shows that singular filaments of scroll waves occur on a set of one-dimensional curves which may be either closed loops or infinite lines.

  8. [Medical management of cervical arterial dissections].

    Science.gov (United States)

    Vuillier, F; Tatu, L; Moulin, T

    2002-12-01

    Medical management of cervical arterial dissections is not standardized and has not been the subject of randomized trials. Management is mainly based on the presumed pathophysiology of secondary cerebral infarcts associated with dissections and the individual experience of each treating team. First, a review of the literature regarding medical management of acute and chronic dissections is presented. Then, results from a national study sponsored by the Société Française Neuro-Vasculaire and the Société Française de Neuro-Radiologie evaluating the medical management of this pathology in French neuro-vascular centers will be presented. These data will be useful to generate practical management recommendations and establish guidelines for further studies.

  9. A Study of Spiral Tap with Large Diameter

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The design and manufacture of spiral tap yet are in r esearch stage at present. This paper mainly introduces how to calculate its geom etric parameters and scientific selection of them with vector method. In additio n, an empiric formula of the tool life of spiral tap with large diameter is esta blished by method of correlation. The practice of design, manufacture and applying proves the advantage of spiral tap by the comparison between the spiral tap and common tap with same size. In the application of...

  10. Topological Signatures in the Electronic Structure of Graphene Spirals

    DEFF Research Database (Denmark)

    Avdoshenko, Stas.M.; Koskinen, Pekka; Sevincli, Haldun

    2013-01-01

    constrained by space curvature, graphene spirals have topologically protected states due to time-reversal symmetry. In addition, we argue that the synthesis of such graphene spirals is feasible and can be achieved through advanced bottom-up experimental routes that we indicate in this work....... and graphene systems. Here, we introduce topologically distinct graphene forms - graphene spirals - and employ density-functional theory to investigate their geometric and electronic properties. We found that the spiral topology gives rise to an intrinsic Rashba spin-orbit splitting. Through a Hamiltonian...

  11. Algorithms for computing efficient, electric-propulsion, spiralling trajectories Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop techniques for rapidly designing many-revolution, electric-propulsion, spiralling trajectories, including the effects of shadowing, gravity harmonics, and...

  12. The nature of dissection: Exploring student conceptions

    Science.gov (United States)

    York, Katharine

    The model of conceptual change in science describes the process of learning as a complete restructuring of knowledge, when learners discover or are shown more plausible, intelligent alternatives to existing conceptions. Emotions have been acknowledged as part of a learner's conceptual ecology, but the effects of emotions on learning have yet to be described. This research was conducted to examine the role that emotions have on learning for thirteen high school students, as they dissected cats in a Human Anatomy and Physiology class. The project also investigated whether a student's emotional reactions may be used to develop a sense of connectedness with the nonhuman world, which is defined as ecological literacy. This study utilized a grounded theory approach, in which student responses to interviews were the primary source of data. Interviews were transcribed, and responses were coded according to a constant comparative method of analysis. Responses were compared with the four conditions necessary for conceptual change to occur, and also to five principles of ecological literacy. Students who had negative reactions to dissection participated less in the activity, and demonstrated less conceptual change. Two female students showed the strongest emotional reactions to dissection, and also the lowest amount of conceptual change. One male student also had strong negative reactions to death, and showed no conceptual change. The dissection experiences of the students in this study did not generally reflect ecological principles. The two students whose emotional reactions to dissection were the most negative demonstrated the highest degree of ecological literacy. These results provide empirical evidence of the effects that emotions have on learning, and also supports the opinions of educators who do not favor dissection, because it does not teach students to respect all forms of life.

  13. Simultaneous multi-tear exclusion:an optimal strategy for type B thoracic aortic dissection initially proved by a single center's 8 years experience

    Institute of Scientific and Technical Information of China (English)

    YUAN Liang-xi; BAO Jun-min; ZHAO Zhi-qing; FENG Xiang; OU Le-feng; FENG Rui; LU Qing-sheng; MEI Zhi-jun; JING Zai-ping

    2007-01-01

    Background Endovascular stent-grafting is widely used to treat thoracic aortic dissection.However,little information is available regarding outcome following simultaneous exclusion of multiple tears.This report details eight years of experience using simultaneous multi-tear exclusion for treatment of Stanford type B thoracic aortic dissection resulting in successful aortic remodeling without adverse events.Methods From September 1998 to January 2006,29 type B thoracic aortic dissection patients(24 men,5 women;27 chronic,2 acute;mean age 58 years,range 45-77 years)were treated by simultaneous multi-tear exclusion in our center.Magnetic resonance angiography was used as the preoperative evaluation method.Different kinds of stent-grafts were used.The patients were followed up with contrast-enhanced spiral computed tomography at 6 months postoperatively and yearly thereafter.Results Twenty-nine surgeries were completed successfully using at least 2 stent-grafts per patient(range:2-6,mean:2.7).No major procedure-related complications,such as rupture,paraplegia,aortic branch ischemia or cerebral infarction,were observed.During follow-up,favorable remodeling of the aorta was observed.Conclusions The mid-term result of thoracic aortic dissection with simultaneous multi-tear exclusion was satisfactory.With the improvement of stent-grafts,simultaneous multi-tear exclusion should find wider application and become an optimal strategy for thoracic aortic dissection.

  14. Spinal accessory nerve function following neck dissection.

    Science.gov (United States)

    Zibordi, F; Baiocco, F; Bascelli, C; Bini, A; Canepa, A

    1988-01-01

    Spinal accessory nerve (SAN) function was evaluated by electromyography (EMG) and muscle testing in 36 patients who underwent neck dissection with SAN preservation. The results emphasized that SAN function was relatively good after conservative neck surgery. Muscle testing findings showed better function than did EMG findings. After surgery the trapezius muscle functioned more efficiently than the sternocleidomastoid (SCM) muscle probably because of the more traumatic surgical handling of both the SCM muscle and its SAN branch. In order to obtain the functional advantages of SAN preservation, the authors suggest that the conservative procedure in radical neck dissection be used whenever warranted by oncologic diagnosis.

  15. [Surgery of aortic dissection: for which patient?].

    Science.gov (United States)

    Verhoye, Jean-Philippe; Abouliatim, Issam; Larralde, Antoine; Beneux, Xavier; Heautot, Jean-François

    2011-01-01

    In the acute stage (less than two weeks), surgery is indicated for Stanford type A aortic dissections. With respect to the initial work-up, surgery consists in replacing the ascending aorta, sometimes the aortic arch (with supra aortic vessels reimplantation), and aortic valve replacement (valve replacement, Bentall valved tube or valve sparing Tyron David technique). Ischemic visceral complications must be searched for and treated by endovascular techniques or surgery. Aneurismal evolution of chronic dissections must be treated surgically. Replacement can encompass the entire aorta. Copyright © 2010. Published by Elsevier Masson SAS.

  16. A Unified Scaling Law in Spiral Galaxies.

    Science.gov (United States)

    Koda; Sofue; Wada

    2000-03-01

    We investigate the origin of a unified scaling relation in spiral galaxies. Observed spiral galaxies are spread on a plane in the three-dimensional logarithmic space of luminosity L, radius R, and rotation velocity V. The plane is expressed as L~&parl0;VR&parr0;alpha in the I passband, where alpha is a constant. On the plane, observed galaxies are distributed in an elongated region which looks like the shape of a surfboard. The well-known scaling relations L-V (Tully-Fisher [TF] relation), V-R (also the TF relation), and R-L (Freeman's law) can be understood as oblique projections of the surfboard-like plane into two-dimensional spaces. This unified interpretation of the known scaling relations should be a clue to understand the physical origin of all the relations consistently. Furthermore, this interpretation can also explain why previous studies could not find any correlation between TF residuals and radius. In order to clarify the origin of this plane, we simulate formation and evolution of spiral galaxies with the N-body/smoothed particle hydrodynamics method, including cooling, star formation, and stellar feedback. Initial conditions are set to 14 isolated spheres with two free parameters, such as mass and angular momentum. The cold dark matter (h=0.5, Omega0=1) cosmology is considered as a test case. The simulations provide the following two conclusions: (1) The slope of the plane is well reproduced but the zero point is not. This zero-point discrepancy could be solved in a low-density (Omega00.5) cosmology. (2) The surfboard-shaped plane can be explained by the control of galactic mass and angular momentum.

  17. The ordered distribution of natural numbers on the square root spiral

    CERN Document Server

    Hahn, Harry K

    2007-01-01

    Natural numbers divisible by the same prime factor lie on defined spiral graphs which are running through the Square Root Spiral (also named as the Spiral of Theodorus or Wurzel Spirale or Einstein Spiral). Prime Numbers also clearly accumulate on such spiral graphs. And the square numbers 4, 9, 16, 25, 36,... form a highly three-symmetrical system of three spiral graphs, which divides the square-root-spiral into three equal areas. A mathematical analysis shows that these spiral graphs are defined by quadratic polynomials. Fibonacci number sequences also play a part in the structure of the Square Root Spiral. Fibonacci Numbers divide the Square Root Spiral into areas and angle sectors with constant proportions. These proportions are linked to the golden mean (or golden section), which behaves as a self-avoiding-walk-constant in the lattice-like structure of the square root spiral.

  18. Spiral phase contrast imaging in microscopy.

    Science.gov (United States)

    Fürhapter, Severin; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika

    2005-02-07

    We demonstrate an optical method for edge contrast enhancement in light microscopy. The method is based on holographic Fourier plane filtering of the microscopic image with a spiral phase element (also called vortex phase or helical phase filter) displayed as an off-axis hologram at a computer controlled high resolution spatial light modulator (SLM) in the optical imaging pathway. The phase hologram imprints a helical phase term of the form exp(i phi) on the diffracted light field in its Fourier plane. In the image plane, this results in a strong and isotropic edge contrast enhancement for both amplitude and phase objects.

  19. SPIRAL2/DESIR high resolution mass separator

    Energy Technology Data Exchange (ETDEWEB)

    Kurtukian-Nieto, T., E-mail: kurtukia@cenbg.in2p3.fr [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Baartman, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver B.C., V6T 2A3 (Canada); Blank, B.; Chiron, T. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Davids, C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Delalee, F. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Duval, M. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); El Abbeir, S.; Fournier, A. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Lunney, D. [CSNSM-IN2P3-CNRS, Université de Paris Sud, F-91405 Orsay (France); Méot, F. [BNL, Upton, Long Island, New York (United States); Serani, L. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Stodel, M.-H.; Varenne, F. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); and others

    2013-12-15

    DESIR is the low-energy part of the SPIRAL2 ISOL facility under construction at GANIL. DESIR includes a high-resolution mass separator (HRS) with a designed resolving power m/Δm of 31,000 for a 1 π-mm-mrad beam emittance, obtained using a high-intensity beam cooling device. The proposed design consists of two 90-degree magnetic dipoles, complemented by electrostatic quadrupoles, sextupoles, and a multipole, arranged in a symmetric configuration to minimize aberrations. A detailed description of the design and results of extensive simulations are given.

  20. Spin gap in a spiral staircase model

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, M.N. [Institut fuer Theoretische Physik und Astrophysik, Wuerzburg Universitaet, Am Hubland, D-97074 Wuerzburg (Germany)]. E-mail: kiselev@physik.uni-wuerzburg.de; Aristov, D.N. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Kikoin, K. [Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2005-04-30

    We investigate the formation of spin gap in one-dimensional models characterized by the groups with hidden symmetries. We introduce a new class of Hamiltonians for description of spin staircases-the spin systems intermediate between 2-leg ladders and S=1 spin chains. The spin exchange anisotropy along legs is described by the angle of spiral twist. The properties of a special case of spin rotator chain (SRC) corresponding to a flat 1-leg ladder is considered by means of fermionization approach based on Jordan-Wigner transformation. The influence of dynamical hidden symmetries on the scaling properties of the spin gap is discussed.

  1. Parity effects in 120° spin spirals.

    Science.gov (United States)

    Menzel, Matthias; Kubetzka, André; von Bergmann, Kirsten; Wiesendanger, Roland

    2014-01-31

    The magnetic ground state of biatomic Fe chains on the reconstructed (5×1)-Ir(001) surface is a cycloidal 120° spin spiral. Spin-resolved scanning tunneling microscopy reveals a striking variation of magnetic field dependences among the chains, which we attribute to parity effects resulting from finite lengths. Numerical simulations show that the chains are divided in three symmetry classes with the exact number of atoms in the chain determining the size and direction of their net magnetic moment. In contrast to antiferromagnetic systems, the three-atom periodicity causes the effective anisotropy to alternate between out of plane, in plane, and quenched.

  2. Spiral orbits and oscillations in historical dynamics

    CERN Document Server

    Cheon, Taksu

    2015-01-01

    We introduce the concept of metaasabiya, the second non-material resource, to the asabiya theory of historical dynamics. We find that the resulting three variable dynamical system has peculiar features such as repelling or attracting axes and spiralling orbits in the phase space. Depending on the initial state, the system can go through series of oscillatory rises and falls, mimicking the geopolitical evolution of real-world polities. These distinctive features, absent in conventional Lotka-Volterra type biological systems, reveal the hidden richness inherent in the asabiya theory.

  3. Importance of packing in spiral defect chaos

    Indian Academy of Sciences (India)

    Kapilanjan Krishna

    2008-04-01

    We develop two measures to characterize the geometry of patterns exhibited by the state of spiral defect chaos, a weakly turbulent regime of Rayleigh-Bénard convection. These describe the packing of contiguous stripes within the pattern by quantifying their length and nearest-neighbor distributions. The distributions evolve towards unique distribution with increasing Rayleigh number that suggests power-law scaling for the dynamics in the limit of infinite system size. The techniques are generally applicable to patterns that are reducible to a binary representation.

  4. Strategies to preserve or regenerate spiral ganglion neurons.

    Science.gov (United States)

    Roehm, Pamela C; Hansen, Marlan R

    2005-10-01

    Degeneration of spiral ganglion neurons following hair cell loss carries critical implications for efforts to rehabilitate severe cases of hearing loss with cochlear implants or hair cell regeneration. This review considers recently identified neurotrophic factors and therapeutic strategies which promote spiral ganglion neuron survival and neurite growth. Replacement of these factors may help preserve or regenerate the auditory nerve in patients with extensive hair cell loss. Spiral ganglion neurons depend on neurotrophic factors supplied by hair cells and other targets for their development and continued survival. Loss of this trophic support leads to spiral ganglion neuron death via apoptosis. Hair cells support spiral ganglion neuron survival by producing several peptide neurotrophic factors such as neurotrophin-3 and glial derived neurotrophic factor. In addition, neurotransmitter release from the hair cells drives membrane electrical activity in spiral ganglion neurons which also supports their survival. In animal models, replacement of peptide neurotrophic factors or electrical stimulation with an implanted electrode attenuates spiral ganglion neuron degeneration following deafferentation. Cell death inhibitors can also preserve spiral ganglion neuron populations. Preliminary studies show that transfer of stem cells or neurons from other ganglia are two potential strategies to replace lost spiral ganglion neurons. Inducing the regrowth of spiral ganglion neuron peripheral processes to approximate or contact cochlear implant electrodes may help optimize signaling from a diminished population of neurons. Recent studies of spiral ganglion neuron development and survival have identified several trophic and neuritogenic factors which protect these specialized cells from degeneration following hair cell loss. While still preliminary, such strategies show promise for future clinical applications.

  5. Self-destructing Spiral Waves: Global Simulations of a Spiral-wave Instability in Accretion Disks

    Science.gov (United States)

    Bae, Jaehan; Nelson, Richard P.; Hartmann, Lee; Richard, Samuel

    2016-09-01

    We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ˜ 5 × 10-4 in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10-5. This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.

  6. Controlling Spiral Dynamics in Excitable Media by a Weakly Localized Pacing

    Institute of Scientific and Technical Information of China (English)

    LI Bing-Wei; SUN Li-Li; CHEN Bin; YING He-Ping

    2007-01-01

    @@ Spiral dynamics controlled by a weakly localized pacing around the spiral tip is investigated. Numerical simulations show two distinct characteristics when the pacing is applied with the weak amplitude for suitable frequencies:for a rigidly rotating spiral, a transition from rigid rotation to meandering motion is observed, and for unstable spiral waves, spiral breakup can be prevented. Successfully preventing spiral breakup is relevant to the modulation of the tip trajectory induced by a localized pacing.

  7. Spontaneous healing of spontaneous coronary artery dissection.

    Science.gov (United States)

    Almafragi, Amar; Convens, Carl; Heuvel, Paul Van Den

    2010-01-01

    Spontaneous coronary artery dissection (SCAD) is a rare cause of acute coronary syndrome and sudden cardiac death. It should be suspected in every healthy young woman without cardiac risk factors, especially during the peripartum or postpartum periods. It is important to check for a history of drug abuse, collagen vascular disease or blunt trauma of the chest. Coronary angiography is essential for diagnosis and early management. We wonder whether thrombolysis might aggravate coronary dissection. All types of treatment (medical therapy, percutaneous intervention or surgery) improve the prognosis without affecting survival times if used appropriately according to the clinical stability and the angiographic features of the involved coronary arteries. Prompt recognition and targeted treatment improve outcomes. We report a case of SCAD in a young female free of traditional cardiovascular risk factors, who presented six hours after thrombolysis for ST elevation myocardial infarction. Coronary angiography showed a dissection of the left anterior descending and immediate branch. She had successful coronary artery bypass grafting, with complete healing of left anterior descending dissection.

  8. Triangular dissections, aperiodic tilings and Jones algebras

    CERN Document Server

    Coquereaux, Robert

    1994-01-01

    The Brattelli diagram associated with a given bicolored Dynkin-Coxeter graph of type A_n determines planar fractal sets obtained by infinite dissections of a given triangle. All triangles appearing in the dissection process have angles that are multiples of \\pi/ (n+1). There are usually several possible infinite dissections compatible with a given n but a given one makes use of n/2 triangle types if n is even. Jones algebra with index [ 4 \\ \\cos^2{\\pi \\over n+1}]^{-1} (values of the discrete range) act naturally on vector spaces associated with those fractal sets. Triangles of a given type are always congruent at each step of the dissection process. In the particular case n=4, there are isometric and the whole structure lead, after proper inflation, to aperiodic Penrose tilings. The other "tilings" associated with other values of the index are discussed and shown to be encoded by equivalence classes of infinite sequences (with appropriate constraints) using only n/2 digits (if n is even) and generalizing the ...

  9. Nested Dissection Interface Reconstruction in Pececillo

    Energy Technology Data Exchange (ETDEWEB)

    Jibben, Zechariah Joel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-31

    A nested dissection method for interface reconstruction in a volume tracking framework has been implemented in Pececillo. This method provides a significant improvement over the traditional onion-skin method, which does not appropriately handle T-shaped multimaterial intersections and dynamic contact lines present in additive manufacturing simulations. The resulting implementation lays the groundwork for further re- search in numerical contact angle estimates.

  10. Spontaneous resolution late after aortic dissection

    NARCIS (Netherlands)

    Zeebregts, CJAM; Schepens, MAAM; Vermeulen, FEE

    A 50-year-old man was operated on for acute type I (DeBakey classification) aortic dissection. The supracoronary ascending aorta was replaced with an interposition graft. Postoperative computed tomography and angiography clearly revealed a double-barrelled aortic arch, left common carotid artery and

  11. Outcome After Surgery for Acute Aortic Dissection

    DEFF Research Database (Denmark)

    Chemtob, Raphaelle Avigael; Møller-Sørensen, Hasse; Holmvang, Lene

    2017-01-01

    Objectives Outcome in patients with acute coronary syndrome (ACS) is improved with dual antiplatelet therapy (DAPT). Patients with acute aortic dissection type A (AAD) often present with similar symptoms and may therefore be prescribed DAPT before diagnosis. The aim of this study was to evaluate...

  12. Dissection in Pre-college Education

    OpenAIRE

    Buyukmihci, NC

    2016-01-01

    This paper discusses the educational and ethical issues surrounding dissection of non-human animals in pre-college education. It argues that this exercise has no benefits to students that could possibly be outweighed by the death of healthy animals killed for this purpose.

  13. Conservative management of chronic aortic dissection with underlying aortic aneurysm

    Directory of Open Access Journals (Sweden)

    Mohammad Yusuf Beebeejaun

    2013-01-01

    Full Text Available Aortic dissection is one of the most common aortic emergencies affecting around 2000 Americans each year. It usually presents in the acute state but in a small percentage of patients aortic dissections go unnoticed and these patients survive without any adequate therapy. With recent advances in medical care and diagnostic technologies, aortic dissection can be successfully managed through surgical or medical options, consequently increasing the related survival rate. However, little is known about the optimal long-term management of patients suffering from chronic aortic dissection. The purpose of the present report is to review aortic dissection, namely its pathology and the current diagnostic tools available, and to discuss the management options for chronic aortic dissection, infiltrates or pleural effusions. Other tion. We report a patient in which chronic aortic dissection presented with recurring episodes of vomiting and also discuss the management plan of our patient who had a chronic aortic dissection as well as an underlying aortic aneurysm.

  14. Genetics Home Reference: familial thoracic aortic aneurysm and dissection

    Science.gov (United States)

    ... Conditions familial TAAD familial thoracic aortic aneurysm and dissection Printable PDF Open All Close All Enable Javascript ... collapse boxes. Description Familial thoracic aortic aneurysm and dissection ( familial TAAD ) involves problems with the aorta , which ...

  15. Coronary Artery Dissection: Not Just a Heart Attack

    Science.gov (United States)

    ... Disease Venous Thromboembolism Aortic Aneurysm More Coronary Artery Dissection: Not Just a Heart Attack Updated:Oct 4, ... cannot reach the heart muscle. Spontaneous coronary artery dissection (SCAD) is an uncommon occurrence, but because it ...

  16. Renal infarction resulting from traumatic renal artery dissection.

    Science.gov (United States)

    Kang, Kyung Pyo; Lee, Sik; Kim, Won; Jin, Gong Yong; Na, Ki Ryang; Yun, Il Yong; Park, Sung Kwang

    2008-06-01

    Renal artery dissection may be caused by iatrogenic injury, trauma, underlying arterial diseases such as fibromuscular disease, atherosclerotic disease, or connective tissue disease. Radiological imaging may be helpful in detecting renal artery pathology, such as renal artery dissection. For patients with acute, isolated renal artery dissection, surgical treatment, endovascular management, or medical treatment have been considered effective measures to preserve renal function. We report a case of renal infarction that came about as a consequence of renal artery dissection.

  17. Spiraling Into Gallstone Disease: A Physicist's Spin

    Science.gov (United States)

    Zastavker, Y. V.; Tilley, B. S.; Pratt, J. C.

    2005-10-01

    Scientists have been fascinated for decades with the ability of nature to form self-assembled structures of various configurations. One such configuration is a spiral or a helix. The (double) helical geometrical configuration is a well-known secondary structure of DNA; however, DNA is not the only biological system possessing this shape. Spirals have been found in a variety of biological and synthetic systems, one of which is bile in the gallbladder. In this system, helical ribbons appear as metastable intermediates in the process of cholesterol crystallization that leads to the formation of gallstones. The bile system is particularly interesting and unique due to the richness in variety of the helical structures formed. Understanding the mechanisms for nature's self-assembly of helical ribbons is crucial in both the prevention of gallstone disease and in developing potential technological and medical applications. We describe a model bile system, composed of three major components of native bile in water: a phospholipid, a fatty acid, and a sterol. This system behaves similarly to the native bile in terms of the kinetics of the formation and evolution of intermediate metastables, including helical ribbons. We further describe our experimental findings and phenomenological model explaining the geometrical shape, elastic properties, and behavior of helical ribbons in model bile systems. We also propose possible applications of these structures as drug delivery vehicles, metallization templates, and antifouling devices.

  18. Spiral-shaped reactor for water disinfection

    KAUST Repository

    Soukane, Sofiane

    2016-04-20

    Chlorine-based processes are still widely used for water disinfection. The disinfection process for municipal water consumption is usually carried out in large tanks, specifically designed to verify several hydraulic and disinfection criteria. The hydrodynamic behavior of contact tanks of different shapes, each with an approximate total volume of 50,000 m3, was analyzed by solving turbulent momentum transport equations with a computational fluid dynamics code, namely ANSYS fluent. Numerical experiments of a tracer pulse were performed for each design to generate flow through curves and investigate species residence time distribution for different inlet flow rates, ranging from 3 to 12 m3 s−1. A new nature-inspired Conch tank design whose shape follows an Archimedean spiral was then developed. The spiral design is shown to strongly outperform the other tanks’ designs for all the selected plug flow criteria with an enhancement in efficiency, less short circuiting, and an order of magnitude improvement in mixing and dispersion. Moreover, following the intensification philosophy, after 50% reduction in its size, the new design retains its properties and still gives far better results than the classical shapes.

  19. Spiral thickenings in the axial Parenchyma of Chrysobalanaceae

    NARCIS (Netherlands)

    Welle, ter B.J.H.

    1976-01-01

    Spiral thickenings in the axial parenchyma, seldom recorded in the secondary xylem of the dicotyledons so far, are described for a number of genera and/or species of Chrysobalanaceae. In 66 out of 99 samples investigated, representing most genera of the Chrysobalanaceae, spiral thickenings proved to

  20. On galaxy spiral arms' nature as revealed by rotation frequencies

    NARCIS (Netherlands)

    Roca-Fabrega, Santi; Valenzuela, Octavio; Figueras, Francesca; Romero-Gomez, Merce; Velazquez, Hector; Antoja Castelltort, Teresa; Pichardo, Barbara

    2013-01-01

    High-resolution N-body simulations using different codes and initial condition techniques reveal two different behaviours for the rotation frequency of transient spiral arms like structures. Whereas unbarred discs present spiral arms nearly corotating with disc particles, strong barred models (bulge

  1. Star formation in galaxies: the role of spiral arms

    CERN Document Server

    Dobbs, Clare

    2013-01-01

    Studying star formation in spiral arms tells us not only about the evolution of star formation, and molecular clouds, but can also tell us about the nature of spiral structure in galaxies. I will address both these topics using the results of recent simulations and observations. Galactic scale simulations are beginning to examine in detail the evolution of GMCs as they form in spiral arms, and then disperse by stellar feedback or shear. The overall timescale for this process appears comparable to the crossing time of the GMCs, a few Myrs for $10^5$ M$_{\\odot}$ clouds, 20 Myr or so for more massive GMCs. Both simulations and observations show that the massive clouds are found in the spiral arms, likely as a result of cloud-cloud collisions. Simulations including stars should also tell us about the stellar age distribution in GMCs, and across spiral arms. More generally, recent work on spiral galaxies suggests that the dynamics of gas flows in spiral arms are different in longlived and transient spiral arms, re...

  2. Analysis on Spiral Search Pattern for Moving Target

    Institute of Scientific and Technical Information of China (English)

    E Qun; MA Yuan-liang; ZHOU Zhou; WANG Ming-chen; WANG Lian-zhu

    2008-01-01

    The distribution function of the target moving in constant velocity and linear course and its meeting condition to the searcher are analyzed. Another proof method for spiral search pattern is presented and the mathematic model of the target possible position is established when performing the linear search. Base on them, the wrong idea about the spiral search pattern can be avoided.

  3. The cold interstellar medium - An HI view of spiral galaxies

    NARCIS (Netherlands)

    Sancisi, R; Bender, R; Davies, RL

    1996-01-01

    An HI view of spiral galaxies is presented. In the first part the standard picture of isolated, normal spiral galaxies is briefly reviewed. In the second part attention is drawn to all those phenomena, such as tidal interactions, accretion and mergers, that depend on the galaxy environment and seem

  4. Ray transfer matrix for a spiral phase plate.

    Science.gov (United States)

    Eggleston, M; Godat, T; Munro, E; Alonso, M A; Shi, H; Bhattacharya, M

    2013-12-01

    We present a ray transfer matrix for a spiral phase plate. Using this matrix we determine the stability of an optical resonator made of two spiral phase plates and trace stable ray orbits in the resonator. Our results should be relevant to laser physics, optical micromanipulation, quantum information, and optomechanics.

  5. Homoclinic (Heteroclinic) Orbit of Complex Dynamical System and Spiral Structure

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Da; LIU Shi-Kuo; LIANG Fu-Ming; XIN Guo-Jun

    2005-01-01

    Starting from iterated systems, it is shown that the homoclinic (heteroclinic) orbit is a kind of spiral structure. The emphasis is laid to show that there are homoclinic or heteroclinic orbits in complex discrete and continuous systems, and these homoclinic or heteroclinic orbits are some kind of spiral structure.

  6. A Systematic Study on Scaling Law of Spiral Waves

    Institute of Scientific and Technical Information of China (English)

    ShufengBAI; QiOUYANG

    1999-01-01

    The study of spiral waves in the Belousov-Zhabotinsky (BZ) reaction has generated fruitful results since the invention of the open spatial reactor.However,some theories are only unsubstantiated and need additional verifications.Our experimental results give a new scaling law of simple and quasi-periodic spiral waves,providing corroborations for some theories and challenge some others.

  7. Spiral Arm of the Perseus Is Closer than Thought

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ It is easy for us to observe the magnificent spiral galaxies outside the Milky Way with a telescope. Although our own galaxy is also believed to have similar spiral arms to those observed in the universe, astronomers have difficulties in rendering the structure because we are living inside it.

  8. Ekman Spiral in Horizontally Inhomogeneous Ocean with Varying Eddy Viscosity

    Science.gov (United States)

    2015-01-01

    1 Ekman Spiral in Horizontally Inhomogeneous Ocean with Varying Eddy Viscosity...Oceanography Naval Postgraduate School, Monterey, California, USA Manuscript Click here to download Manuscript: Ekman -chu-pageoph-rev.docx 1...currently valid OMB control number. 1. REPORT DATE 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Ekman Spiral

  9. Drift of Spiral Waves in Complex Ginzburg-Landau Equation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations.

  10. Design considerations for an archimedean slot spiral antenna

    Science.gov (United States)

    Nurnberger, Michael W.; Volakis, John L.

    1995-01-01

    The design goal is to develop a 118-157 MHz, vertically polarized, low-profile (or conformal) antenna as a replacement for VHF AM blade antennas on aircraft. This design is to be arrived at by scaling the dimensions of an antenna designed for a center frequency of 1.1 GHz. The design prior to scaling may have the following maximum dimensions: diameter less than 3.70 in. and thickness less than 0.50 in. Although a four-arm spiral design was originally suggested, a two-arm spiral may also be used, as both mode-1 and mode-2 (sum and difference) radiation patterns aren't required. While a four-arm spiral can easily be designed should both sum and difference patterns be required, the two-arm design will provide the required sum pattern and simplify the design problem somewhat: only one feed is required, and the feed area geometry is more straightforward. Polarization requirements dictate that a slot spiral be used, as opposed to a wire spiral. Two similar radiating structures were considered. The first is the standard archimedean spiral antenna. The second is a hollow archimedean spiral antenna, essentially a standard archimedean spiral with the inner portion removed.

  11. The risk for type B aortic dissection in Marfan syndrome

    NARCIS (Netherlands)

    den Hartog, Alexander W.; Franken, Romy; Zwinderman, Aeilko H.; Timmermans, Janneke; Scholte, Arthur J.; van den Berg, Maarten P.; de Waard, Vivian; Pals, Gerard; Mulder, Barbara J. M.; Groenink, Maarten

    2015-01-01

    BACKGROUND: Aortic dissections involving the descending aorta are a major clinical problem in patients with Marfan syndrome. OBJECTIVES: The purpose of this study was to identify clinical parameters associated with type B aortic dissection and to develop a risk model to predict type B aortic dissect

  12. [Nodes Dissections. What's up and what is at stake?].

    Science.gov (United States)

    Guillemin, François; Marchal, Frédéric

    2014-04-01

    Radical nodes dissection has a diagnostic value and can play a part in the treatment. Its interest could be questionable according to efficacy of the associated treatments either adjuvant or neo-adjuvant. Above all, sentinel node dissection allows to avoid a radical dissection with deleterious effects.

  13. Novel Dissection Station for Endolaryngeal Microsurgery and Laser Surgery: Development and Dissection Course Experience.

    Science.gov (United States)

    Mattioli, Francesco; Presutti, Livio; Caversaccio, Marco; Bonali, Marco; Anschuetz, Lukas

    2017-06-01

    Objective We aimed to develop and validate an ex vivo dissection station for endolaryngeal surgery suitable for different kinds of laryngeal specimen and any type of operating technique (CO2 laser, cold instruments by endoscopic or microscopic techniques). Study Design Experimental construction and validation of a highly specialized dissection station. Setting Laboratory and international dissection course. Methods We designed a lightweight dissection station made of polycarbonate resin approved for use with a CO2 laser. The cylindrical box hosts an articulated laryngeal support. The laryngoscope is positioned on an articulated arm, which is fixed on the construction's footplate. Validation of the larynx box was performed during an international dissection course on laryngeal surgery held in January 2016. Results We assessed the suitability of our novel dissection station among specialized laryngologists with a mean experience of 14 years. Feedback from the participants was very positive, with a mean general impression of 9.5 (out of 10 points) and a recommendation score of 9.6 for further use. Its utility in transforming the taught surgical steps into daily practice has been highly recognized, with a score of 9.5. Conclusion The lightweight and transparent larynx box is suitable for any kind of laryngeal specimen, and any surgical intervention can be taught at reasonable cost. It is safe and suitable for use with CO2 lasers. Validation among experienced surgeons revealed its suitability in the teaching of endolaryngeal microsurgery and laser surgery.

  14. Effects of non Newtonian spiral blood flow through arterial stenosis

    Science.gov (United States)

    Hasan, Md. Mahmudul; Maruf, Mahbub Alam; Ali, Mohammad

    2016-07-01

    The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system. A numerical investigation is carried out to analyze the effect of spiral blood flow through an axisymmetric three dimensional artery having 75% stenosis at the center. Blood is assumed as a Non-Newtonian fluid. Standard k-ω model is used for the simulation with the Reynolds number of 1000. A parabolic velocity profile with spiral flow is used as inlet boundary condition. The peak values of all velocity components are found just after stenosis. But total pressure gradually decreases at downstream. Spiral flow of blood has significant effects on tangential component of velocity. However, the effect is mild for radial and axial velocity components. The peak value of wall shear stress is at the stenosis zone and decreases rapidly in downstream. The effect of spiral flow is significant for turbulent kinetic energy. Detailed investigation and relevant pathological issues are delineated throughout the paper.

  15. Scale Heights of Non-Edge-on Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    Tao Hu; Qiu-He Peng; Ying-He Zhao

    2006-01-01

    We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson's equation for a logarithmic disturbance of matter density in spiral galaxies. We show that the spiral arms can not extend to inside the "forbidden radius" γ0, due to the effect of the finite thickness of the disk. The method is tested by re-calculating the scale heights of 71 northern spiral galaxies previously calculated by Ma, Peng & Gu.Our results differ from theirs by less than 9%. We also present the scale heights of a further 23 non-edge-on spiral galaxies.

  16. The Effects of Spiral Taping Treatment on Low Back Pain

    Directory of Open Access Journals (Sweden)

    Hwang Jae-Ok

    2006-02-01

    Full Text Available Objective : The purpose of this study is to estimate the effects of spiral taping treatment on low back pain. Methods : 420 low back pain patients were treated with spiral taping or spiral taping plus herbal medicine, and no other treatments such as acupuncture, herbal acupuncture, and chiropractic therapy were added. We evaluated the improvement by physical examination and pain. Results : 364 patients felt no pain or inconvenience of daily life and 43 patients showed improvement of pain or symptom after 1 month of treatment. 13 patients showed same pain with before treatment. Conclusions : These results suggest spiral taping treatments contribute to the improvement of low back pain. Further study is needed for the confirmation of this effect of spiral taping treatments on low back pain.

  17. A Photometrically and Spectroscopically Confirmed Population of Passive Spiral Galaxies

    CERN Document Server

    Fraser-McKelvie, Amelia; Pimbblet, Kevin A; Dolley, Tim; Crossett, Jacob P; Bonne, Nicolas J

    2016-01-01

    We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z<0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph (WiFeS) to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption-line spectra with 4000\\AA\\ breaks consistent with an average luminosity-weighted age of 2.3 Gyr. Our photometric and IFU spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.

  18. Spirals in protoplanetary disks from photon travel time

    CERN Document Server

    Kama, M; Heays, A N

    2016-01-01

    Spiral structures are a common feature in scattered-light images of protoplanetary disks, and of great interest as possible tracers of the presence of planets. However, other mechanisms have been put foward to explain them, including self-gravity, disk-envelope interactions, and dead zone boundaries. These mechanisms explain many spirals very well, but are unable to easily account for very loosely wound spirals and single spiral arms. We study the effect of light travel time on the shape of a shadow cast by a clump orbiting close (within ${\\sim}1\\,$au) of the central star, where there can be significant orbital motion during the light travel time from the clump to the outer disk and then to the sky plane. This delay in light rays reaching the sky plane gives rise to a variety of spiral- and arc-shaped shadows, which we describe with a general fitting formula for a flared, inclined disk.

  19. Self-perpetuating Spiral Arms in Disk Galaxies

    Science.gov (United States)

    D'Onghia, Elena; Vogelsberger, Mark; Hernquist, Lars

    2013-03-01

    The causes of spiral structure in galaxies remain uncertain. Leaving aside the grand bisymmetric spirals with their own well-known complications, here we consider the possibility that multi-armed spiral features originate from density inhomogeneities orbiting within disks. Using high-resolution N-body simulations, we follow the motions of stars under the influence of gravity, and show that mass concentrations with properties similar to those of giant molecular clouds can induce the development of spiral arms through a process termed swing amplification. However, unlike in earlier work, we demonstrate that the eventual response of the disk can be highly non-linear, significantly modifying the formation and longevity of the resulting patterns. Contrary to expectations, ragged spiral structures can thus survive at least in a statistical sense long after the original perturbing influence has been removed.

  20. Effect of Annular Slit Geometry on Characteristics of Spiral Jet

    Institute of Scientific and Technical Information of China (English)

    Shigeru Matsuo; Kwon-Hee Lee; Shinsuke Oda; Toshiaki Setoguchi; Heuy-Dong Kim

    2003-01-01

    A spiral flow using an annular slit connected to a conical cylinder does not need special device to generate a tangential velocity component of the flow and differs from swirling flows. Pressurized fluid is supplied to an annular chamber and injected into the convergent nozzle through the annular slit. The annular jet develops into the spiral flow. In the present study, a spiral jet discharged out of nozzle exit was obtained by using a convergent nozzle and an annular slit set in nozzle inlet, and the effect of annular slit geometry on characteristics of the spiral jet was investigated by using a Laser Doppler Velocimeter (LDV) experimentally. Furthermore, velocity distributions of the spiral jet were compared with those of a normal jet.

  1. Two-dimensional optical thermal ratchets based on Fibonacci spirals.

    Science.gov (United States)

    Xiao, Ke; Roichman, Yael; Grier, David G

    2011-07-01

    An ensemble of symmetric potential energy wells arranged at the vertices of a Fibonacci spiral can serve as the basis for an irreducibly two-dimensional thermal ratchet. Periodic rotation of the potential energy landscape through a three-step cycle drives trapped Brownian particles along spiral trajectories through the pattern. Which spiral is selected depends on the angular displacement at each step, with transitions between selected spirals arising at rational proportions of the golden angle. Fibonacci spiral ratchets therefore display an exceptionally rich range of transport properties, including inhomogeneous states in which different parts of the pattern induce motion in different directions. Both the radial and angular components of these trajectories can undergo flux reversal as a function of the scale of the pattern or the rate of rotation.

  2. Breakup of spiral wave under different boundary conditions

    Institute of Scientific and Technical Information of China (English)

    Zhao Ying-Kui; Wang Guang-Rui; Chen Shi-Gang

    2007-01-01

    In this paper, we investigate the breakup of spiral wave under no-flux, periodic and Dirichlet boundary conditions respectively. When the parameter ε is close to a critical value for Doppler-induced wave breakup, the instability of the system caused by the boundary effect occurs in the last two cases, resulting in the breakup of spiral wave near the boundary. With our defined average order measure of spiral wave (AOMSW), we quantify the degree of order of the system when the boundary-induced breakup of spiral wave happens. By analysing the AOMSW and outer diameter R of the spiral tip orbit, it is easy to find that this boundary effect is correlated with large values of R, especially under the Dirichlet boundary condition. This correlation is nonlinear, so the AOMSW sometimes oscillates with the variation of ε.

  3. Suppression of Spiral Wave in Modified Orengonator Model

    Institute of Scientific and Technical Information of China (English)

    MA Jun; JIN Wu-Yin; YI Ming; WANG Chun-Ni

    2008-01-01

    In this paper, a spatial perturbation scheme is proposed to suppress the spiral wave in the modified Orengonator model, which is used to describe the chemical reaction in the light-sensitive media. The controllable external illumination Φ is perturbed with a spatial linear function. In our numerical simulation, the scheme is investigated by imposing the external controllable illumination on the space continuously and/or intermittently. The numerical simulation results confirm that the stable rotating spiral wave still can be removed with the scheme proposed in this paper even if the controllable Φ changed vs. time and space synchronously. Then the scheme is also used to control the spiral wave and turbulence in the modified Fitzhugh-Nagumo model It is found that the scheme is effective to remove the sable rotating and meandering spiral wave but it costs long transient period and intensity of the gradient parameter to eliminate the spiral turbulence.

  4. Axillary dissection versus no axillary dissection in patients with sentinel-node micrometastases (IBCSG 23-01)

    DEFF Research Database (Denmark)

    Galimberti, Viviana; Cole, Bernard F; Zurrida, Stefano

    2013-01-01

    For patients with breast cancer and metastases in the sentinel nodes, axillary dissection has been standard treatment. However, for patients with limited sentinel-node involvement, axillary dissection might be overtreatment. We designed IBCSG trial 23-01 to determine whether no axillary dissection...... was non-inferior to axillary dissection in patients with one or more micrometastatic (≤2 mm) sentinel nodes and tumour of maximum 5 cm....

  5. Which Comes First: The Use of Computer Simulation of Frog Dissection or Conventional Dissection as Academic Exercise?

    Science.gov (United States)

    Akpan, Joseph; Strayer, Jeremy

    2010-01-01

    Science educators and school administrators are reexamining the educational value of animal dissection in the nation's schools and are focusing on simulation as an instructional alternative. One implication of the debate is that simulations can lead to equivalent learning to hands-on dissection. The second implication is whether dissection is…

  6. Which Comes First: The Use of Computer Simulation of Frog Dissection or Conventional Dissection as Academic Exercise?

    Science.gov (United States)

    Akpan, Joseph; Strayer, Jeremy

    2010-01-01

    Science educators and school administrators are reexamining the educational value of animal dissection in the nation's schools and are focusing on simulation as an instructional alternative. One implication of the debate is that simulations can lead to equivalent learning to hands-on dissection. The second implication is whether dissection is…

  7. Gas velocity patterns in simulated galaxies: Observational diagnostics of spiral structure theories

    CERN Document Server

    Baba, Junichi; Miyamoto, Yusuke; Egusa, Fumi; Kuno, Nario

    2016-01-01

    There are two theories of stellar spiral arms in isolated disc galaxies that model stellar spiral arms with different longevities: quasi-stationary density wave theory, which characterises spirals as rigidly rotating, long-lived patterns (i.e. steady spirals), and dynamic spiral theory, which characterises spirals as differentially rotating, transient, recurrent patterns (i.e. dynamic spirals). In order to discriminate between these two spiral models observationally, we investigated the differences between the gas velocity patterns predicted by these two spiral models in hydrodynamic simulations. We found that the azimuthal phases of the velocity patterns relative to the gas density peaks (i.e. gaseous arms) differ between the two models, as do the gas flows; nevertheless, the velocity patterns themselves are similar for both models. Such similarity suggests that the mere existence of streaming motions does not conclusively confirm the steady spiral model. However, we found that the steady spiral model shows ...

  8. Spiral CT venography in central venous obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jin Wook; Park, Jae Hyung; Im, Jung Gi; Han, Moon Hee; Kim, In One; Chang, Kee Hyun; Yeon, Kyung Mo [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of); Song, Chi Sung [Boramae Hospital, Seoul (Korea, Republic of)

    1998-11-01

    To determine the clinical usefulness of spiral computed tomographic (CT) venography for the evaluation of central venous obstruction. The authors prospectively performed a total of 29 spiral CT venography procedures in 25 consecutive patients with suspected central venous obstrucion. Diluted contrast media were directly injected into the peripheral veins of the hand or the foot. Scan parameters were 3mm X-ray beam collimation, table speed of 4-6cm/sec, scan time of 32-40sec, and injection delay of 20 sec. Axial images were reconstructed at 2-mm intervals, and using shaded surface display(SSD), maximum intensity projection(MIP), and multiplanar reformation(MPR), 3-D reconstruction was performed. In all cases, ascending venograp-hy(n=3D13) and/or direct catheter venography (n=3D21) was performed within 2 days of CT venography. With regard to site, extent, extent, severity, and cause of obstruction and collateral circulation, we compared the results of CT and contrast venography. In 24 patients, a total of 56 sites of central venous obstruction or stenosis (>50%) were demonstrated. The causes of obstruction were venous thrombosis(n=3D6), malignant tumors(n=3D4), arteriovenous fistula for hemodialysis(n=3D5), extrinsic compression(n=3D2), coincidence of extrinsic compression and arteriovenous fistula(n=3D1), pacemaker(n=3D1), mediastinal inflammatory pseudotumor(n=3D1), spinal tuberculosis(n=3D1), membranous obstruction of the hepatic inferior vena cava(n=3D1), Behcet's disease(n=3D1), or unknown cause(n=3D1). When compared with ascending venography(n=3D13), CT venography was superior for evaluation of the extent and cause of obstruction and collateral circulation in two, four and one case(s), respectively. For the evaluation of site and severity of obstruction, CT venography was equal to ascending venography. In two cases, direct catheter venography (n=3D21) was superior to CT venography for evaluating the obstruction site, but in three, five and one case

  9. A Laboratory Manual for Stepwise Cerebral White Matter Fiber Dissection.

    Science.gov (United States)

    Koutsarnakis, Christos; Liakos, Faidon; Kalyvas, Aristotelis V; Sakas, Damianos E; Stranjalis, George

    2015-08-01

    White matter fiber dissection is an important method in acquiring a thorough neuroanatomic knowledge for surgical practice. Previous studies have definitely improved our understanding of intrinsic brain anatomy and emphasized on the significance of this technique in modern neurosurgery. However, current literature lacks a complete and concentrated laboratory guide about the entire dissection procedure. Hence, our primary objective is to introduce a detailed laboratory manual for cerebral white matter dissection by highlighting consecutive dissection steps, and to stress important technical comments facilitating this complex procedure. Twenty adult, formalin-fixed cerebral hemispheres were included in the study. Ten specimens were dissected in the lateromedial and 10 in the mediolateral direction, respectively, using the fiber dissection technique and the microscope. Eleven and 8 consecutive and distinctive dissection steps are recommended for the lateromedial and mediolateral dissection procedures, respectively. Photographs highlighting various anatomic landmarks accompany every step. Technical recommendations, facilitating the dissection process, are also indicated. The fiber dissection technique, although complex and time consuming, offers a three-dimensional knowledge of intrinsic brain anatomy and architecture, thus improving both the quality of microneurosurgery and the patient's standard of care. The present anatomic study provides a thorough dissection manual to those who study brain anatomy using this technique. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Nuclear spirals in the inner Milky Way

    Science.gov (United States)

    Ridley, Matthew G. L.; Sormani, Mattia C.; Treß, Robin G.; Magorrian, John; Klessen, Ralf S.

    2017-08-01

    We use hydrodynamical simulations to construct a new coherent picture for the gas flow in the Central Molecular Zone (CMZ), the region of our Galaxy within R ≲ 500 pc. We relate connected structures observed in (l, b, v) data cubes of molecular tracers to nuclear spiral arms. These arise naturally in hydrodynamical simulations of barred galaxies, and are similar to those that can be seen in external galaxies such as NGC 4303 or NGC 1097. We discuss a face-on view of the CMZ, including the positions of several prominent molecular clouds, such as Sgr B2, the 20 and 50 km s-1 clouds, the polar arc, Bania Clump 2 and Sgr C. Our model is also consistent with the larger scale gas flow, up to R ≃ 3 kpc, thus providing a consistent picture of the entire Galactic bar region.

  11. Digital spiral object identification using random light

    CERN Document Server

    Yang, Zhe; Mirhosseini, Mohammad; Zhou, Yiyu; Gao, Boshen; Gao, Lu; Rafsanjani, Seyed Mohammad Hashemi; Long, Guilu; Boyd, Robert W

    2016-01-01

    Photons that are entangled or correlated in orbital angular momentum have been extensively used for remote sensing, object identification and imaging. It has recently been demonstrated that intensity fluctuations give rise to the formation of correlations in the orbital angular momentum components and angular positions of random light. Here, we demonstrate that the spatial signatures and phase information of an object, with rotational symmetries, can be identified using classical orbital angular momentum correlations in random light. The Fourier components imprinted in the digital spiral spectrum of the object, measured through intensity correlations, unveil its spatial and phase information. Sharing similarities with conventional compressive sensing protocols that exploit sparsity to reduce the number of measurements required to reconstruct a signal, our technique allows sensing of an object with fewer measurements than other schemes that use pixel-by-pixel imaging. One remarkable advantage of our technique ...

  12. Spiral shocks and accretion in discs

    Energy Technology Data Exchange (ETDEWEB)

    Spruit, H.C.; Matsuda, T.; Inoue, M.; Sawada, K.

    1987-12-01

    Recent numerical and analytical results on disc-like accretion with shock waves as the only dissipation mechanism are compared. The global properties of the process are similar to those of the viscous (..cap alpha..) disc model, but precise values of the effective ..cap alpha.. value as a function of the accretion rate can be calculated. At low values of the ratio of specific heats (..gamma.. < 1.45) accretion is possible without radiative losses. Such adiabatic accretion can occur in practice at high accretion rates on to low mass objects and may be important in the formation of planets. Following previous authors, it is pointed out that non-axisymmetric perturbations in the outer parts of a disc increase in amplitude as they propagate in and cause spiral shocks more easily in a disc than perturbations originating in the inner parts.

  13. Characterizing spiral arm and interarm star formation

    CERN Document Server

    Kreckel, K; Schinnerer, E; Groves, B; Adamo, A; Hughes, A; Meidt, S

    2016-01-01

    Interarm star formation contributes significantly to a galaxy's star formation budget, and provides an opportunity to study stellar birthplaces unperturbed by spiral arm dynamics. Using optical integral field spectroscopy of the nearby galaxy NGC 628 with VLT/MUSE, we identify 391 HII regions at 35pc resolution over 12 kpc^2. Using tracers sensitive to the underlying gravitational potential, we associate HII regions with either arm (271) or interarm (120) environments. We find that most HII region physical properties (luminosity, size, metallicity, ionization parameter) are independent of environment. We calculate the fraction of Halpha luminosity due to the diffuse ionized gas (DIG) background contaminating each HII region, and find the DIG surface brightness to be higher within HII regions compared to the surroundings, and slightly higher within arm HII regions. Use of the temperature sensitive [SII]/Halpha line ratio map instead of the Halpha surface brightness to identify HII region boundaries does not ch...

  14. Spontaneous Coronary Artery Dissection: The Phantom Menace

    Science.gov (United States)

    Spinthakis, Nikolaos; Abdulkareem, Nada; Farag, Mohamed; Gorog, Diana A.

    2016-01-01

    We present a case of a 66-year-old lady with chest pain, without dynamic 12-lead electrocardiographic (ECG) changes and normal serial troponin. Coronary angiography revealed a linear filing defect in the first obtuse marginal branch of the circumflex artery indicating coronary artery dissection, with superadded thrombus. She was managed medically with dual antiplatelet therapy and has responded well. Spontaneous coronary artery dissection (SCAD) is a rare cause of cardiac chest pain, which can be missed without coronary angiography. Unlike most other lesions in patients with unstable symptoms, where coronary intervention with stenting is recommended, patients with SCAD generally fare better with conservative measures than with intervention, unless there is hemodynamic instability. PMID:28197295

  15. Endoscopic submucosal dissection for gastrointestinal neoplasms

    Institute of Scientific and Technical Information of China (English)

    Naomi Kakushima; Mitsuhiro Fujishiro

    2008-01-01

    Endoscopic submucosal dissection (ESD) is an advanced technique of therapeutic endoscopy for superficial gastrointestinal neoplasms. Three steps characterize it:injecting fluid into the submucosa to elevate the lesion,cutting the surrounding mucosa of the lesion, and dissecting the submucosa beneath the lesion. The ESD technique has rapidly permeated in Japan for treatment of early gastric cancer, due to its excellent results of enbloc resection compared to endoscopic mucosal resection (EMR). Although there is still room for improvement to lessen its technical difficulty, ESD has recently been applied to esophageal and colorectal neoplasms.Favorable short-term results have been reported, but the application of ESD should be well considered by three aspects: (1) the possibility of nodal metastases of the lesion, (2) technical difficulty such as location, ulceration and operator's skill, and (3) organ characteristics.

  16. Counter traction makes endoscopic submucosal dissection easier.

    Science.gov (United States)

    Oyama, Tsuneo

    2012-11-01

    Poor counter traction and poor field of vision make endoscopic submucosal dissection (ESD) difficult. Good counter traction allows dissections to be performed more quickly and safely. Position change, which utilizes gravity, is the simplest method to create a clear field of vision. It is useful especially for esophageal and colon ESD. The second easiest method is clip with line method. Counter traction made by clip with line accomplishes the creation of a clear field of vision and suitable counter traction thereby making ESD more efficient and safe. The author published this method in 2002. The name ESD was not established in those days; the name cutting endoscopic mucosal resection (EMR) or EMR with hook knife was used. The other traction methods such as external grasping forceps, internal traction, double channel scope, and double scopes method are introduced in this paper. A good strategy for creating counter traction makes ESD easier.

  17. Endoscopic submucosal dissection for stomach neoplasms

    Institute of Scientific and Technical Information of China (English)

    Mitsuhiro Fujishiro

    2006-01-01

    Recent advances in techniques of therapeutic endoscopy for stomach neoplasms are rapidly achieved. One of the major topics in this field is endoscopic submucosal dissection (ESD). ESD is a new endoscopic technique using cutting devices to remove the tumor by thefollowing three steps: injecting fluid into the submucosa to elevate the tumor from the muscle layer, pre-cutting the surrounding mucosa of the tumor, and dissecting the connective tissue of the submucosa beneath the tumor. So the tumors are resectable in an en bloc fashion, regardless of the size, shape, coexisting ulcer,and location. Indication for ESD is strictly confined by two aspects: the possibility of nodal metastases and technical difficulty, which depends on the operators. Although long-term outcome data are still lacking, short-term outcomes of ESD are extremely favourable and laparotomy with gastrectomy is replaced with ESD in some parts of therapeutic strategy for early gastric cancer.

  18. Effects of Spiral Arms on Star Formation in Nuclear Rings of Barred-spiral Galaxies

    CERN Document Server

    Seo, Woo-Young

    2014-01-01

    We use hydrodynamic simulations to study the effect of spiral arms on the star formation rate (SFR) occurring in nuclear rings of barred-spiral galaxies. We find that spiral arms can be an efficient means of gas transport from the outskirts to the central parts, provided that the arms are rotating slower than the bar. While the ring star formation in models with no-arm or corotating arms is active only during about the bar growth phase, arm-driven gas accretion makes the ring star formation both enhanced and prolonged significantly in models with slow-rotating arms. The arm-enhanced SFR is larger by a factor of ~ 3-20 than in the no-arm model, with larger values corresponding to stronger and slower arms. Arm-induced mass inflows also make dust lanes stronger. Nuclear rings in slow-arm models are ~ 45% larger than in the no-arm counterparts. Star clusters that form in a nuclear ring exhibit an age gradient in the azimuthal direction only when the SFR is small, whereas no noticeable age gradient is found in the...

  19. Aortic growth rates in chronic aortic dissection

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, A.M. [Department of Radiology, Division of Thoracic Radiology, University of Michigan Medical Center (United States)]. E-mail: ainekell@med.umich.edu; Quint, L.E. [Department of Radiology, Division of Thoracic Radiology, University of Michigan Medical Center (United States); Nan, B. [School of Public Health, University of Michigan, Ann Arbor, Michigan (United States); Zheng, J. [School of Public Health, University of Michigan, Ann Arbor, Michigan (United States); Cronin, P. [Department of Radiology, Division of Thoracic Radiology, University of Michigan Medical Center (United States); Deeb, G.M. [Division of Cardiac Surgery, University of Michigan Medical Center (United States); Williams, D.M. [Division of Vascular Interventional Imaging, University of Michigan Medical Center (United States)

    2007-09-15

    Aim: To determine and compare rates of descending aortic enlargement and complications in chronic aortic dissection with and without a proximal aortic graft. Methods and materials: Fifty-two patients with dissection involving the descending aorta and who had undergone at least two computed tomography (CT) examinations at our institution between November, 1993 and February, 2004 were identified, including 24 non-operated patients (four type A, 20 type B) and 28 operated patients (type A). CT examinations per patient ranged from two to 10, and follow-up ranged from 1-123 months (mean 49 months, median 38.5 months). On each CT image, the aortic short axis (SA), false lumen (FL), and true lumen (TL) diameters were measured at the longitudinal midpoint of the dissection and at the point of maximum aortic diameter. Complications were tabulated, including aortic rupture and aortic enlargement requiring surgery. Results: For non-operated patients, the midpoint and maximum point SA, TL, and FL diameters increased significantly over time. For operated patients, the midpoint and maximum point SA and FL diameters increased significantly over time. In both groups, aortic enlargement was predominantly due to FL expansion. Diameter increases in non-operated patients were significantly larger than those in operated patients. The rate of change in aortic diameter was constant, regardless of aortic size. Four non-operated and six operated patients developed aortic complications. Conclusions: In patients with a dissection involving the descending thoracic aorta, the FL increased in diameter over time, at a constant rate, and to a greater degree in non-operated patients (mostly type B) compared with operated patients (all type A)

  20. Fever of unknown origin in aortic dissection.

    Science.gov (United States)

    Yuan, S-M

    2017-05-01

    Aortic dissection is the most devastating sequela of thoracic aortic disorder. Patients with acute aortic dissection typically manifest as an acute onset of severe chest pain, but occasionally present with atypical symptoms including fever of unknown origin. A total of 50 patients from 41 articles based on a complete literature retrieval were included in this study. More patients had a fever prior to pain. The time to presentation was 40.7 ± 105.6 days, the time to diagnosis was 52.9 ± 110.1 days, and the time to surgery/intervention was 1.8 ± 5.6 days. The patients' temperature on admission was 38.2 ± 0.6 °C and the maximal temperature recorded was 38.8 ± 0.4 °C. Laboratory findings showed increased white blood cell counts, cardiac enzymes, and inflammatory biomarkers. More pronounced laboratory findings of the infectious type than the inflammatory type aortic dissection could be helpful in the differential diagnosis. Half of patients warrant aortic repair with or without valve replacement, less than half of patients were conservatively managed, and a few were interventionally treated or were being followed up. The mortality rate was 9.5 %. Physicians should always bear in mind aortic dissection when patients present with fever of unknown origin particularly in those without chest pain. Laboratory findings may offer inflammatory evidence for the diagnosis. An early diagnosis as well as subsequent treatment is indispensable for patients' outcomes.

  1. Nested Dissection Interface Reconstruction in Pececillo

    Energy Technology Data Exchange (ETDEWEB)

    Jibben, Zechariah Joel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Carlson, Neil N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Francois, Marianne M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division

    2016-09-13

    A nested dissection method for interface reconstruction in a volume tracking framework has been implemented in Pececillo, a mini-app for Truchas, which is the ASC code for casting and additive manufacturing. This method provides a significant improvement over the traditional onion-skin method, which does not appropriately handle T-shaped multimaterial intersections and dynamic contact lines present in additive manufacturing simulations. The resulting implementation lays the groundwork for further research in contact angle estimates and surface tension calculations.

  2. The spiral structure of our Milky Way Galaxy

    CERN Document Server

    Hou, L G; Shi, W B

    2009-01-01

    The spiral structure of our Milky Way Galaxy is not yet known. HII regions and Giant molecular clouds are the most prominent spiral tracers. The 2-, 3- and 4-arm models have previously been proposed to outline the structure of our Galaxy. Recently, new data of spiral tracers covering a larger region of the Galactic disk have been published in literature. We wish to obtain the updated spiral structure of the Milky way using all tracer data. We collected the spiral tracer data of our Milky Way from literature, namely, HII regions and giant molecular clouds (GMCs). With the weighting factors based on the excitation parameters of HII regions or the masses of GMCs, we fitted the distribution of these tracers with the models of two-, three-, four-spiral-arms or polynomial spiral arms. The distances of tracers, if not available from stellar or direct measurements, were estimated kinetically from the standard rotation curve of Brand & Blitz (1993) with R_0=8.5 kpc, and \\Theta_0 =220 km s^{-1} or the newly fitted ...

  3. The Nature of Red-Sequence Cluster Spiral Galaxies

    Science.gov (United States)

    Kashur, Lane; Barkhouse, Wayne; Sultanova, Madina; Kalawila Vithanage, Sandanuwa; Archer, Haylee; Foote, Gregory; Mathew, Elijah; Rude, Cody; Lopez-Cruz, Omar

    2017-01-01

    Preliminary analysis of the red-sequence galaxy population from a sample of 57 low-redshift galaxy clusters observed using the KPNO 0.9m telescope and 74 clusters from the WINGS dataset, indicates that a small fraction of red-sequence galaxies have a morphology consistent with spiral systems. For spiral galaxies to acquire the color of elliptical/S0s at a similar luminosity, they must either have been stripped of their star-forming gas at an earlier epoch, or contain a larger than normal fraction of dust. To test these ideas we have compiled a sample of red-sequence spiral galaxies and examined their infrared properties as measured by 2MASS, WISE, Spitzer, and Herschel. These IR data allows us to estimate the amount of dust in each of our red-sequence spiral galaxies. We compare the estimated dust mass in each of these red-sequence late-type galaxies with spiral galaxies located in the same cluster field but having colors inconsistent with the red-sequence. We thus provide a statistical measure to discriminate between purely passive spiral galaxy evolution and dusty spirals to explain the presence of these late-type systems in cluster red-sequences.

  4. Spiral Antenna-Coupled Microbridge Structures for THz Application.

    Science.gov (United States)

    Gou, Jun; Zhang, Tian; Wang, Jun; Jiang, Yadong

    2017-12-01

    Bolometer sensor is a good candidate for THz imaging due to its compact system, low cost, and wideband operation. Based on infrared microbolometer structures, two kinds of antenna-coupled microbridge structures are proposed with different spiral antennas: spiral antenna on support layer and spiral antenna with extended legs. Aiming at applications in detection and imaging, simulations are carried out mainly for optimized absorption at 2.52 THz, which is the radiation frequency of far-infrared CO2 lasers. The effects of rotation angle, line width, and spacing of the spiral antenna on THz wave absorption of microbridge structures are discussed. Spiral antenna, with extended legs, is a good solution for high absorption rate at low absorption frequency and can be used as electrode lead simultaneously for simplified manufacturing process. A spiral antenna-coupled microbridge structure with an absorption rate of more than 75% at 2.52 THz is achieved by optimizing the structure parameters. This research demonstrates the use of different spiral antennas for enhanced and tunable THz absorption of microbridge structures and provides an effective way to fabricate THz microbolometer detectors with great potential in the application of real-time THz imaging.

  5. MRI and MR angiography of vertebral artery dissection

    Energy Technology Data Exchange (ETDEWEB)

    Mascalchi, M. [Cattedra di Radiologia, Universita di Pisa (Italy); Bianchi, M.C. [Servizio di Neuroradiologia, Ospedale S. Chiara, Pisa (Italy); Mangiafico, S. [Servizio di Neuroradiologia, Ospedale di Careggi, Firenze (Italy); Ferrito, G. [Servizio di Neuroradiologia, Ospedali Riuniti, Livorno (Italy); Puglioli, M. [Servizio di Neuroradiologia, Ospedale S. Chiara, Pisa (Italy); Marin, E. [Servizio di Radiologia, Ospedale S. M. Nuova, Firenze (Italy); Mugnai, S. [Clinica Neurologica, Universita di Firenze (Italy); Canapicchi, R. [Servizio di Neuroradiologia, Ospedale S. Chiara, Pisa (Italy); Quilici, N. [Servizio di Neuroradiologia, Ospedali Riuniti, Livorno (Italy); Inzitari, D. [Clinica Neurologica, Universita di Firenze (Italy)

    1997-05-01

    A review of 4,500 angiograms yielded 11 patients with dissection of the vertebral arteries who had MRI and (in 4 patients) MR angiography (MRA) in the acute phase of stroke. One patient with incidental discovery at arteriography of asymptomatic vertebral artery dissection and two patients with acute strokes with MRI and MRA findings consistent with vertebral artery dissection were included. Dissection occurred after neck trauma or chiropractic manipulation in 4 patients and was spontaneous in 10. Dissection involved the extracranial vertebral artery in 9 patients, the extra-intracranial junction in 1, and the intracranial artery in 4. MRI demonstrated infarcts in the brain stem, cerebellum, thalamus or temporo-occipital regions in 7 patients with extra- or extra-intracranial dissections and a solitary lateral medullary infarct in 4 patients (3 with intracranial and 1 with extra-intracranial dissection). In 2 patients no brain abnormality related to vertebral artery dissection was found and in one MRI did not show subarachnoid haemorrhage revealed by CT. Intramural dissecting haematoma appeared as crescentic or rounded high signal on T1-weighted images in 10 patients examined 3-20 days after the onset of symptoms. The abnormal vessel stood out in the low signal cerebrospinal fluid in intracranial dissections, whereas it was more difficult to detect in extracranial dissections because of the intermediate-to-high signal of the normal perivascular structures and slow flow proximal and distal to the dissection. In two patients examined within 36 h of the onset, mural thickening was of intermediate signal intensity on T1-weighted images and high signal on spin-density and T2-weighted images. MRA showed abrupt stenosis in 2 patients and disappearance of flow signal at and distal to the dissection in 5. Follow-up arteriography, MRI or MRA showed findings consistent with occlusion of the dissected vessel in 6 of 8 patients. (orig.). With 7 figs., 3 tabs.

  6. Acute aortic dissection: be aware of misdiagnosis

    Directory of Open Access Journals (Sweden)

    Asteri Theodora

    2009-02-01

    Full Text Available Abstract Background Acute aortic dissection (AAD is a life-threatening condition requiring immediate assessment and therapy. A patient suffering from AAD often presents with an insignificant or irrelevant medical history, giving rise to possible misdiagnosis. The aim of this retrospective study is to address the problem of misdiagnosing AD and the different imaging studies used. Methods From January 2000 to December 2004, 49 patients (41 men and 8 women, aged from 18–75 years old presented to the Emergency Department of our hospital for different reasons and finally diagnosed with AAD. Fifteen of those patients suffered from arterial hypertension, one from giant cell arteritis and another patient from Marfan's syndrome. The diagnosis of AAD was made by chest X-ray, contrast enhanced computed tomography (CT, transthoracic echocardiography (TTE and coronary angiography. Results Initial misdiagnosis occurred in fifteen patients (31% later found to be suffering from AAD. The misdiagnosis was myocardial infarction in 12 patients and cerebral infarction in another three patients. Conclusion Aortic dissection may present with a variety of clinical manifestations, like syncope, chest pain, anuria, pulse deficits, abdominal pain, back pain, or acute congestive heart failure. Nearly a third of the patients found to be suffering from AD, were initially otherwise diagnosed. Key in the management of acute aortic dissection is to maintain a high level of suspicion for this diagnosis.

  7. Whole vitreous humor dissection for vitreodynamic analysis.

    Science.gov (United States)

    Murali, Karthik; Kashani, Amir H; Humayun, Mark S

    2015-05-24

    The authors propose an effective technique to isolate whole, intact vitreous core and cortex from post mortem enucleated porcine eyes. While previous studies have shown the results of such dissections, the detailed steps have not been described, precluding researchers outside the field from replicating their methods. Other studies harvest vitreous either through aspiration, which does not maintain the vitreous structure anatomy, or through partial dissection, which only isolates the vitreous core. The proposed method isolates the whole vitreous body, with the vitreous core and cortex intact, while maintaining vitreous anatomy and structural integrity. In this method, a full thickness scleral flap in an enucleated porcine eye is first created and through this, the choroid tissue can be separated from the sclera. The scleral flap is then expanded and the choroid is completely separated from the sclera. Finally the choroid-retina tissue is peeled off the vitreous to leave an isolated intact vitreous body. The proposed vitreous dissection technique can be used to study physical properties of the vitreous humor. In particular, this method has significance for experimental studies involving drug delivery, vitreo-retinal oxygen transport, and intraocular convection.

  8. Drift of rigidly rotating spirals under periodic and noisy illuminations.

    Science.gov (United States)

    Zhang, Hong; Wu, Ning-Jie; Ying, He-Ping; Hu, Gang; Hu, Bambi

    2004-10-15

    Under the weak deformation approximation, the motion of rigidly rotating spirals induced by periodic and noisy illuminations are investigated analytically. We derive an approximate but explicit formula of the spiral drift velocity directly from the original reaction-diffusion equation. With this formula we are able to explain the main features in the periodic and noisy illuminations induced spiral drift problems. Numerical computations of the Oregonator model are carried out as well, and they agree with the main qualitative conclusions of our analytical results.

  9. Fabrication of Meander and Spiral Type Micro Inductors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To obtain microstructure of magnetic devices, the thin film inductors were fabricated by the process such as thin film manufacturing, photolithography and wet etching. The freouency characteristics of these devices are measured at high frequency range. When the inductor sizes of the spiral and the meander type are same, the inductance and the quality factor of the spiral type inductor are larger than those of the meander type inductor, but the driving frequency of the spiral type inductor is lower than that of the meander type inductor.

  10. Spiral Magnetic Order in the One-Dimensional Kondo Lattice

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-Rong; LI Zheng-Zhong; SHEN Rui

    2001-01-01

    The effects of c-f (conduction-f electrons) hybridization on the spiral spin magnetism in the one dimensional Kondo lattice are studied. By using the mean-field approximation, a close set of equations of the Green's functions with arbitrary wave vector Q for the spiral ordering of spins is deduced. The magnetic phase boundary between the spiral magnetism and ferromagnetism has been calculated approximately. From our qualitative results, one can find that the ferromagnetic region is enlarged due to the c f hybridization. Moreover, some new results reflecting the Kondo effect, such as the modified dispersion relation and the weakening of the localized magnetic moments are also obtained.

  11. A Software Development Simulation Model of a Spiral Process

    Science.gov (United States)

    Mizell, Carolyn; Malone, Linda

    2007-01-01

    There is a need for simulation models of software development processes other than the waterfall because processes such as spiral development are becoming more and more popular. The use of a spiral process can make the inherently difficult job of cost and schedule estimation even more challenging due to its evolutionary nature, but this allows for a more flexible process that can better meet customers' needs. This paper will present a discrete event simulation model of spiral development that can be used to analyze cost and schedule effects of using such a process in comparison to a waterfall process.

  12. Measurements of the equivalent thicknesses of three-dimensional spiral galactic disks

    Institute of Scientific and Technical Information of China (English)

    Gang Li; Zhi-Quan Luo; Qiu-He Peng

    2009-01-01

    Spiral arms are fitted after the data from the latest spiral galactic images re-leased by the Sloan Digital Sky Survey are processed. Equivalent thicknesses of 42 spiral galactic disks are derived, which increase the foundational data for further research about spiral galaxies.

  13. Intrinsic inhomogeneities and the coexistence of spirals with different periods of rotation.

    Science.gov (United States)

    Tranquillo, Joseph; Howes, Meghan

    2008-11-01

    We propose a mechanism by which wave fronts emanating from a spiral may break far from the spiral core due to intrinsic spatial inhomogeneities. A series of computer simulations are presented to demonstrate how coupling domains, which on their own would not cause breakup, may cause a single spiral to break into many spirals.

  14. Endovascular management of symptomatic cerebral malperfusion due to carotid dissection after type A aortic dissection repair.

    Science.gov (United States)

    Casana, R; Tolva, V; Majnardi, A Robecchi; Bianchi, P G; Addobati, L; Bertoni, G B; Cireni, L V; Silani, V

    2011-10-01

    Type A acute aortic dissection is a surgical emergency, and supra-aortic trunk involvement may be complicated by stroke in 6% to 20% of cases. A 66-year-old Caucasian female patient underwent a composite repair of the ascending aorta for type A aortic dissection. Postoperative period was complicated by episodes of "drop attack." Doppler ultrasound of supra-aortic trunks revealed an intimal flap occluding right internal carotid artery. Multiple stenting was performed from carotid bifurcation to internal carotid artery in order to exclude the dissection intimal flap. After endovascular procedure physiatrist considered that motor functional improvement was better than expected, and we support that endovascular resolution of carotid malperfusion led to a better outcome. According to other experience, endovascular procedure resulted as a safe and effective way. Moreover, ultrasound monitoring of supra-aortic trunks in postoperative period is recommended.

  15. Aortic diameter >or = 5.5 cm is not a good predictor of type A aortic dissection: observations from the International Registry of Acute Aortic Dissection (IRAD)

    National Research Council Canada - National Science Library

    Pape, Linda A; Tsai, Thomas T; Isselbacher, Eric M; Oh, Jae K; O'gara, Patrick T; Evangelista, Arturo; Fattori, Rossella; Meinhardt, Gabriel; Trimarchi, Santi; Bossone, Eduardo; Suzuki, Toru; Cooper, Jeanna V; Froehlich, James B; Nienaber, Christoph A; Eagle, Kim A

    2007-01-01

    .... However, few studies of acute aortic dissection patients and aortic size exist. We used data from our registry of acute aortic dissection patients to better understand the relationship between aortic diameter and type A dissection...

  16. Pattern formation of coupled spiral waves in bilayer systems: rich dynamics and high-frequency dominance.

    Science.gov (United States)

    Nie, Haichun; Gao, Jihua; Zhan, Meng

    2011-11-01

    The interaction of two spiral waves with independent frequencies in a bilayer oscillatory medium (one spiral in each layer) and with a symmetric coupling e is studied. If the spirals have different frequencies, the faster spiral is unaffected by the slower one, and the slower can show a variety of behaviors, which depend on e and include, in order of increasing e, phase drifting, amplitude modulation, amplitude domination, and phase synchronization. This high-frequency dominance, the asymmetric driving-response effect under the condition of a symmetric coupling, is generic and independent of whether the coupled spiral waves are outwardly rotating or inwardly rotating spirals. If the spirals have identical frequencies, they may even show complete synchronization, parallel drift, or circular drift, depending on the relative rotation direction of the two spirals and their initial separation distance. Comparisons with coupled spirals in monolayer media, previous works on coupled spirals in bilayer systems, and coupled phase oscillators are made.

  17. Peer-Assisted Learning in a Gross Anatomy Dissection Course.

    Science.gov (United States)

    Han, Eui-Ryoung; Chung, Eun-Kyung; Nam, Kwang-Il

    2015-01-01

    Peer-assisted learning encourages students to participate more actively in the dissection process and promotes thoughtful dissection. We implemented peer-assisted dissection in 2012 and compared its effects on students' self-assessments of learning and their academic achievement with those of faculty-led dissection. All subjects performed dissections after a lecture about upper-limb gross anatomy. Experimental group (n = 134) dissected a cadaver while guided by peer tutors who had prepared for the dissection in advance, and control group (n = 71) dissected a cadaver after the introduction by a faculty via prosection. Self-assessment scores regarding the learning objectives related to upper limbs were significantly higher in experimental group than in control group. Additionally, experimental group received significantly higher academic scores than did control group. The students in peer-assisted learning perceived themselves as having a better understanding of course content and achieved better academic results compared with those who participated in faculty-led dissection. Peer-assisted dissection contributed to self-perception and to the ability to retain and explain anatomical knowledge.

  18. Background music in the dissection laboratory: impact on stress associated with the dissection experience.

    Science.gov (United States)

    Anyanwu, Emeka G

    2015-06-01

    Notable challenges, such as mental distress, boredom, negative moods, and attitudes, have been associated with learning in the cadaver dissection laboratory (CDL). The ability of background music (BM) to enhance the cognitive abilities of students is well documented. The present study was designed to investigate the impact of BM in the CDL and on stress associated with the dissection experience. After 8 wk of normal dissection without BM, various genres of BM were introduced into the cadaver dissection sessions of 260 medical and dental students for 3 wk. Feedback on the impact of BM on students in the CDL and students' attitude were accessed using a questionnaire. Psychological stress assessment was done using Psychological Stress Measure 9. Two batches of 30 students each were made to dissect same areas of the body for 2 h, one batch with BM playing and the other batch without. The same examination was given to both groups at the end. Over 90% of the participants expressed a desire to incorporate BM into the CDL; 87% of the sampled population that expressed love for music also reported BM to be a very useful tool that could be used to enhance learning conditions in the CDL. A strong positive relationship was established between love for music and its perception as a tool for learning in the CDL (P < 0.001). Students that studied under the influence of BM had significantly higher scores (P < 0.001) in the overall examination result. BM reduced the level of stress associated with the dissection experience by ∼33%. Copyright © 2015 The American Physiological Society.

  19. Effects of semiclassical spiral fluctuations on hole dynamics

    Science.gov (United States)

    Hamad, I. J.; Manuel, L. O.; Trumper, A. E.

    2012-01-01

    We investigate the dynamics of a single hole coupled to the spiral fluctuations related to the magnetic ground states of the antiferromagnetic J1-J2-J3 Heisenberg model on a square lattice. Using exact diagonalization on finite size clusters and the self-consistent Born approximation in the thermodynamic limit, we find, as a general feature, a strong reduction of the quasiparticle weight along the spiral phases of the magnetic phase diagram. For an important region of the Brillouin zone the hole spectral functions are completely incoherent, whereas at low energies the spectral weight is redistributed on several irregular peaks. We find a characteristic value of the spiral pitch Q=(0.7,0.7)π, for which the available phase space for hole scattering is maximum. We argue that this behavior is due to the nontrivial interference of the magnon-assisted and the free-hopping mechanism for hole motion, characteristic of a hole coupled to semiclassical spiral fluctuations.

  20. Spiral formation at microscale by μ-pyro-electrospinning

    Science.gov (United States)

    Mecozzi, L.; Gennari, O.; Rega, R.; Grilli, S.; Bhowmick, S.; Gioffrè, M. A.; Coppola, G.; Ferraro, P.

    2016-05-01

    Spiral shapes occur frequently in nature, such as in case of snail shells or in case of the so-called cochlea, namely the auditory portion of the inner ear. They also inspire many technological devices that take advantage of this geometry. Here we show that μ-pyro electrospinning is able to control the whipping instabilities in order to form polymeric spirals directly onto the target support and with true regularity at microscale. The results show that the polymer concentration plays a key role in producing reliable and long spirals. We investigate the cell response to these spiral templates that, thanks to their true regularity, would be useful for developing innovative cochlea regeneration scaffolds.

  1. Halpha Morphologies and Environmental Effects in Virgo Cluster Spiral Galaxies

    CERN Document Server

    Koopmann, R A

    2004-01-01

    We describe the various Halpha morphologies of Virgo Cluster and isolated spiral galaxies, and associate the Halpha morphologies with the types of environmental interactions which have altered the cluster galaxies. The spatial distributions of Halpha and R-band emission are used to divide the star formation morphologies of the 52 Virgo Cluster spirals into several categories: normal (37%), anemic (6%), enhanced (6%), and (spatially) truncated (52%). Truncated galaxies are further subdivided based on their inner star formation rates into truncated/normal (37%), truncated/compact (6%), truncated/anemic (8%), and truncated/enhanced (2%). The fraction of anemic galaxies is relatively small (6-13%) in both environments, suggesting that starvation is not a major factor in the reduced star formation rates of Virgo spirals. The majority of Virgo spiral galaxies have their Halpha disks truncated (52%), whereas truncated Halpha disks are rarer in isolated galaxies (12%). Most of the Halpha-truncated galaxies have relat...

  2. 'Reading' bubble chamber pictures with the Spiral Reader eyes.

    CERN Multimedia

    1974-01-01

    Interactive techniques were widely used to study bubble chamber pictures. After a visual scanning of the pictures and a vertex measurement on a Shivamatic, the Spiral Reader allowed the track polar coordinates to be easily measured. See photo 7408137X

  3. Topological signatures in the electronic structure of graphene spirals.

    Science.gov (United States)

    Avdoshenko, Stas M; Koskinen, Pekka; Sevinçli, Haldun; Popov, Alexey A; Rocha, Claudia G

    2013-01-01

    Topology is familiar mostly from mathematics, but also natural sciences have found its concepts useful. Those concepts have been used to explain several natural phenomena in biology and physics, and they are particularly relevant for the electronic structure description of topological insulators and graphene systems. Here, we introduce topologically distinct graphene forms - graphene spirals - and employ density-functional theory to investigate their geometric and electronic properties. We found that the spiral topology gives rise to an intrinsic Rashba spin-orbit splitting. Through a Hamiltonian constrained by space curvature, graphene spirals have topologically protected states due to time-reversal symmetry. In addition, we argue that the synthesis of such graphene spirals is feasible and can be achieved through advanced bottom-up experimental routes that we indicate in this work.

  4. CFD numerical simulation of Archimedes spiral inlet hydrocyclone

    Science.gov (United States)

    Zhang, L.; Wei, L.; Chang, B. H.; Xing, J. L.; Jia, K.

    2013-12-01

    For traditional linear type inlet, hydrocyclone has an unstable inner field, high turbulence intensity and low separation efficiency, this paper proposes an inlet mode that uses an Archimedes spiral hydrocyclone. A Mixture liquid-solid multiphase flow model combined with the kinetic theory of granular flow was used to simulate the high concentration water-sand-air three-phase flow in a hydrocyclone. We analyzed the pressure field, velocity field and turbulent kinetic energy and compared with traditional linear type inlet hydrocyclone inner field. The results show that Archimedes spiral inlet hydrocyclone's pressure field is evenly distributed. The Archimedes spiral inlet hydrocyclone can guide and accelerate the mixture flow and produce small forced vortex and less short circuit flow. The particles easily go to the outer vortex and are separated. The Archimedes spiral inlet hydrocyclone has effectively improved the stability of inner flow field and separation efficiency.

  5. Data Fusion Tool for Spiral Bevel Gear Condition Indicator Data

    Science.gov (United States)

    Dempsey, Paula J.; Antolick, Lance J.; Branning, Jeremy S.; Thomas, Josiah

    2014-01-01

    Tests were performed on two spiral bevel gear sets in the NASA Glenn Spiral Bevel Gear Fatigue Test Rig to simulate the fielded failures of spiral bevel gears installed in a helicopter. Gear sets were tested until damage initiated and progressed on two or more gear or pinion teeth. During testing, gear health monitoring data was collected with two different health monitoring systems. Operational parameters were measured with a third data acquisition system. Tooth damage progression was documented with photographs taken at inspection intervals throughout the test. A software tool was developed for fusing the operational data and the vibration based gear condition indicator (CI) data collected from the two health monitoring systems. Results of this study illustrate the benefits of combining the data from all three systems to indicate progression of damage for spiral bevel gears. The tool also enabled evaluation of the effectiveness of each CI with respect to operational conditions and fault mode.

  6. Cassini Discovers a Kinematic Spiral Ring around Saturn

    National Research Council Canada - National Science Library

    S. Charnoz; C. C. Porco; E. Déau; A. Brahic; J. N. Spitale; C. Bacques; K. Baillie

    2005-01-01

    .... New Cassini observations show that these strands, initially interpreted as concentric ring segments, are in fact connected and form a single one-arm trailing spiral winding at least three times around Saturn...

  7. Cassini discovers a kinematic spiral ring around Saturn.

    Science.gov (United States)

    Charnoz, S; Porco, C C; Déau, E; Brahic, A; Spitale, J N; Bacques, G; Baillie, K

    2005-11-25

    Since the time of the Voyager flybys of Saturn in 1980-1981, Saturn's eccentric F ring has been known to be accompanied on either side by faint strands of material. New Cassini observations show that these strands, initially interpreted as concentric ring segments, are in fact connected and form a single one-arm trailing spiral winding at least three times around Saturn. The spiral rotates around Saturn with the orbital motion of its constituent particles. This structure is likely the result of differential orbital motion stretching an initial cloud of particles scattered from the dense core of the F ring. Different scenarios of formation, implying ringlet-satellite interactions, are explored. A recently discovered moon candidate, S/2004 S6, is on an orbit that crosses the F-ring core at the intersection of the spiral with the ring, which suggests a dynamical connection between S/2004 S6 and the spiral.

  8. The role of multislice spiral CT in clinical cardiology

    Energy Technology Data Exchange (ETDEWEB)

    Haberl, R.; Boehme, E.; Richartz, B.; Czernik, A.; Buck, J.; Steinbigler, P. [Medical Hospital I and Department of Radiology, Klinik Muenchen-Pasing, Munich (Germany)

    2004-05-01

    Multislice spiral CT provides diagnostic-quality images of native coronary arteries and bypasses. Indications include prognosis in asymptomatic individuals, detection of significant coronary stenosis, and follow-up after interventions or surgery.

  9. Resonance Related Spiral Substructure in a Galactic Gaseous Disk

    CERN Document Server

    Yáñez, Miguel A; Martos, Marco A; Hayes, John C

    2007-01-01

    We use high resolution 2D hydrodynamic simulations to study the formation of spiral substructure in the gaseous disk of a galaxy. The obtained gaseous response is driven by a self-consistent non-axisymmetric potential obtained from an imposed spiral mass distribution. We highlight the importance of ultraharmonic resonances in generating these features. The temporal evolution of the system is followed with the parallel ZEUS-MP code, and we follow the steepening of perturbations induced by the spiral potential until large-scale shocks emerge. These shocks exhibit bifurcations that protrude from the gaseous arms and continue to steepen until new shocks are formed. When the contribution from the spiral potential relative to the axisymmetric background is increased from our default value, spurs protrude from the main arms after several revolutions of the gaseous disk. Such spurs overlap on top of the aforementioned shocks. These results support the hypothesis that a complicated gaseous response can coexist with an...

  10. A new planar feed for slot spiral antennas

    Science.gov (United States)

    Nurnberger, M. W.; Volakis, J. L.

    1995-01-01

    This report presents a new planar, wideband feed network for a slot spiral antenna, and the subsequent design and performance of a VHF antenna utilizing this feed design. Both input impedance and radiation pattern measurements are presented to demonstrate the performance and usefulness of this feed. Almost all previous designs have utilized wire spirals, requiring bulky, non-planar feeds with separate baluns, and large absorbing cavities. The presented slot spiral antenna feed integrates the balun into the structure of the slot spiral antenna, making the antenna and feed planar. This greatly simplifies the design and construction of the antenna, in addition to providing repeatable accuracy. It also allows the use of a very shallow reflecting cavity for conformal applications. Finally, this feeding approach now makes many of the known miniaturization techniques viable options.

  11. Effects of abnormal excitation on the dynamics of spiral waves

    Science.gov (United States)

    Min-Yi, Deng; Xue-Liang, Zhang; Jing-Yu, Dai

    2016-01-01

    The effect of physiological and pathological abnormal excitation of a myocyte on the spiral waves is investigated based on the cellular automaton model. When the excitability of the medium is high enough, the physiological abnormal excitation causes the spiral wave to meander irregularly and slowly. When the excitability of the medium is low enough, the physiological abnormal excitation leads to a new stable spiral wave. On the other hand, the pathological abnormal excitation destroys the spiral wave and results in the spatiotemporal chaos, which agrees with the clinical conclusion that the early after depolarization is the pro-arrhythmic mechanism of some anti-arrhythmic drugs. The mechanisms underlying these phenomena are analyzed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11365003 and 11165004).

  12. Gas Ejection from Spiral Galaxy Disks

    Science.gov (United States)

    Durelle, Jeremy

    We present the results of three proposed mechanisms for ejection of gas from a spiral arm into the halo. The mechanisms were modelled using magnetohydrodynamics (MHD) as a theoretical template. Each mechanism was run through simulations using a Fortran code: ZEUS-3D, an MHD equation solver. The first mechanism modelled the gas dynamics with a modified Hartmann flow which describes the fluid flow between two parallel plates. We initialized the problem based on observation of lagging halos; that is, that the rotational velocity falls to a zero at some height above the plane of the disk. When adopting a density profile which takes into account the various warm and cold H I and HII molecular clouds, the system evolves very strangely and does not reproduce the steady velocity gradient observed in edge-on galaxies. This density profile, adopted from Martos and Cox (1998), was used in the remaining models. However, when treating a system with a uniform density profile, a stable simulation can result. Next we considered supernova (SN) blasts as a possible mechanism for gas ejection. While a single SN was shown to be insufficient to promote vertical gas structures from the disk, multiple SN explosions proved to be enough to promote gas ejection from the disk. In these simulations, gas ejected to a height of 0.5 kpc at a velocity of 130 km s--1 from 500 supernovae, extending to an approximate maximum height of 1 kpc at a velocity of 6.7 x 103 km s--1 from 1500 supernovae after 0.15 Myr, the approximate time of propagation of a supernova shock wave. Finally, we simulated gas flowing into the spiral arm at such a speed to promote a jump in the disk gas, termed a hydraulic jump. The height of the jump was found to be slightly less than a kiloparsec with a flow velocity of 41 km s--1 into the halo after 167 Myr. The latter models proved to be effective mechanisms through which gas is ejected from the disk whereas the Hartmann flow (or toy model) mechanism remains unclear as the

  13. Rotation curves of 967 spiral galaxies: implications for dark matter.

    Science.gov (United States)

    Persic, M.; Salucci, P.; Stel, F.

    1996-02-01

    The authors present the rotation curves of 967 spiral galaxies, obtained by deprojecting and folding the raw Hα data published by Mathewson et al. (1992). Of these, 80 meet objective excellence criteria and are suitable for individual detailed mass modelling, while 820 are suitable for statistical studies. A preliminary analysis of their properties confirms that rotation curves are a universal function of luminosity and that the dark matter fraction in spirals increases with decreasing luminosity.

  14. Discovery of a low-luminosity spiral DRAGN

    Science.gov (United States)

    Mulcahy, D. D.; Mao, M. Y.; Mitsuishi, I.; Scaife, A. M. M.; Clarke, A. O.; Babazaki, Y.; Kobayashi, H.; Suganuma, R.; Matsumoto, H.; Tawara, Y.

    2016-11-01

    Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only 5 cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75 M⊙ yr-1, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of L1.4 GHz = 1.12 × 1022 W Hz-1, two orders of magnitude smaller than other known spiral DRAGNs. We suggest that this may indicate the existence of a previously unknown low-luminosity population of spiral DRAGNS. FITS cutout image of the observed spiral DRAGN MCG+07-47- 10 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/L8

  15. Spiral and Antispiral Waves in Reaction-Diffusion Systems

    Institute of Scientific and Technical Information of China (English)

    LIUYu-Fang; WUYan-Ning; XUHou-Ju; SUNJin-Feng

    2004-01-01

    Spiral waves are ubiquitous phenomena in nonlinear chemical, physical, and biological systems. But antispiral waves are infrequent to date. The transition between spiral and antispiral waves has been rarely explored. We have analyzed the extended Brusselator model and the extended Oregonator model by linear stability analysis. We have demonstrated that it is possible and plausible to realize the transition between them by control of diffusion coefficient of inactivator from theoretical analysis and numerical simulations.

  16. Anomalous drift of spiral waves in heterogeneous excitable media

    CERN Document Server

    Sridhar, S; Panfilov, Alexander V

    2009-01-01

    We study the drift of spiral waves in a simple model of heterogeneous excitable medium, having gradients in local excitability or cellular coupling. For the first time, we report the anomalous drift of spiral waves towards regions having higher excitability, in contrast to all earlier observations in reaction-diffusion models of excitable media. Such anomalous drift can promote the onset of complex spatio-temporal patterns, e.g., those responsible for life-threatening arrhythmias in the heart.

  17. Period tripling causes rotating spirals in agitated wet granular layers.

    Science.gov (United States)

    Huang, Kai; Rehberg, Ingo

    2011-07-08

    Pattern formation of a thin layer of vertically agitated wet granular matter is investigated experimentally. Rotating spirals with three arms, which correspond to the kinks between regions with different colliding phases, are the dominating pattern. This preferred number of arms corresponds to period tripling of the agitated granular layer, unlike predominantly subharmonic Faraday crispations in dry granular matter. The chirality of the spatiotemporal pattern corresponds to the rotation direction of the spirals.

  18. Mechanism of unpinning spirals by a series of stimuli.

    Science.gov (United States)

    Gao, Xiang; Zhang, Hong

    2014-06-01

    Antitachycardia pacing (ATP) is widely used to terminate tachycardia before it proceeds to lethal fibrillation. The important prerequisite for successful ATP is unpinning of the spirals anchored to the obstacle by a series of stimuli. Here, to understand the mechanism of unpinning spirals by ATP, we propose a theoretical explanation based on a nonlinear eikonal relation and a kinematical model. The theoretical results are quantitatively consistent with the numerical simulations in both weak and high excitabilities.

  19. Golden spirals as phyllotactic arrangements of optical patterns.

    Science.gov (United States)

    Haudin, F; Residori, S

    2013-02-01

    A nonlinear optical medium with nonlocal feedback is shown to have all the necessary ingredients to simulate a growthlike process that generates golden spirals and phyllotactic patterns. Elementary droplets of light are generated by the optical nonlinearity whereas the combination of rotation and translation in the feedback loop geometrically distributes them on spiraling patterns. The symmetry of the geometrical arrangements is described with the help of a simple replication algorithm.

  20. Magnetic field evolution and reversals in spiral galaxies

    Science.gov (United States)

    Dobbs, C. L.; Price, D. J.; Pettitt, A. R.; Bate, M. R.; Tricco, T. S.

    2016-10-01

    We study the evolution of galactic magnetic fields using 3D smoothed particle magnetohydrodynamics (SPMHD) simulations of galaxies with an imposed spiral potential. We consider the appearance of reversals of the field, and amplification of the field. We find that magnetic field reversals occur when the velocity jump across the spiral shock is above ≈20 km s-1, occurring where the velocity change is highest, typically at the inner Lindblad resonance in our models. Reversals also occur at corotation, where the direction of the velocity field reverses in the corotating frame of a spiral arm. They occur earlier with a stronger amplitude spiral potential, and later or not at all with weaker or no spiral arms. The presence of a reversal at radii of around 4-6 kpc in our fiducial model is consistent with a reversal identified in the Milky Way, though we caution that alternative Galaxy models could give a similar reversal. We find that relatively high resolution, a few million particles in SPMHD, is required to produce consistent behaviour of the magnetic field. Amplification of the magnetic field occurs in the models, and while some may be genuinely attributable to differential rotation or spiral arms, some may be a numerical artefact. We check our results using ATHENA, finding reversals but less amplification of the field, suggesting that some of the amplification of the field with SPMHD is numerical.

  1. An investigation into the prominence of spiral galaxy bulges

    CERN Document Server

    Graham, A W

    2001-01-01

    From a diameter-limited sample of 86 `face-on' spiral galaxies, the bulge-to-disk size and luminosity ratios, and other quantitative measurements for the prominence of the bulge are derived. The bulge and disk parameters have been estimated using a seeing convolved Sersic r^(1/n) bulge and a seeing convolved exponential disk. In general, early-type spiral galaxy bulges have Sersic values of n>1, and late-type spiral galaxy bulges have values of n 3-sigma) for the early-type spirals than the late-type spirals. This apparent contradiction with the r_e/h values can be explained with an iceberg-like scenario, in which the bulges in late-type spiral galaxies are relatively submerged in their disk. This can be achieved by varying the relative bulge/disk stellar density while maintaining the same effective bulge-to-disk size ratio. The absolute bulge magnitude - log(n) diagram is used as a diagnostic tool for comparative studies with dwarf elliptical and ordinary elliptical galaxies. At least in the B-band, these ob...

  2. Galaxy Zoo: star formation versus spiral arm number

    Science.gov (United States)

    Hart, Ross E.; Bamford, Steven P.; Casteels, Kevin R. V.; Kruk, Sandor J.; Lintott, Chris J.; Masters, Karen L.

    2017-06-01

    Spiral arms are common features in low-redshift disc galaxies, and are prominent sites of star formation and dust obscuration. However, spiral structure can take many forms: from galaxies displaying two strong 'grand design' arms to those with many 'flocculent' arms. We investigate how these different arm types are related to a galaxy's star formation and gas properties by making use of visual spiral arm number measurements from Galaxy Zoo 2. We combine ultraviolet and mid-infrared (MIR) photometry from GALEX and WISE to measure the rates and relative fractions of obscured and unobscured star formation in a sample of low-redshift SDSS spirals. Total star formation rate has little dependence on spiral arm multiplicity, but two-armed spirals convert their gas to stars more efficiently. We find significant differences in the fraction of obscured star formation: an additional ˜10 per cent of star formation in two-armed galaxies is identified via MIR dust emission, compared to that in many-armed galaxies. The latter are also significantly offset below the IRX-β relation for low-redshift star-forming galaxies. We present several explanations for these differences versus arm number: variations in the spatial distribution, sizes or clearing time-scales of star-forming regions (i.e. molecular clouds), or contrasting recent star formation histories.

  3. IC3328 a "dwarf elliptical galaxy" with spiral structure

    CERN Document Server

    Jerjen, H; Binggeli, B; Jerjen, Helmut; Kalnajs, Agris; Binggeli, Bruno

    2000-01-01

    We present the 2-D photometric decomposition of the Virgo galaxy IC3328. The analysis of the global light distribution of this morphologically classified nucleated dwarf elliptical galaxy (dE1,N) reveals a tightly wound, bi-symmetric spiral structure with a diameter of 4.5 kpc, precisely centered on the nucleus of the dwarf. The amplitude of the spiral is only three percent of the dwarf's surface brightness making it the faintest and smallest spiral ever found in a galaxy. In terms of pitch angle and arm winding the spiral is similar to the intermediate-type galaxy M51, but it lacks the dust and prominent HII regions which signal the presence of gas. The visual evidence of a spiral pattern in an early-type dwarf galaxy reopens the question on whether these dwarfs are genuine rotationally supported or anisotropic stellar systems. In the case of IC3328, we argue for a nearly face-on disk (dS0) galaxy with an estimated maximum rotation velocity of v_c,max = 55kms-1. The faintness of the spiral and the small moti...

  4. Spiral structure in nearby galaxies II. comparative analysis and conclusions

    CERN Document Server

    Kendall, S; Kennicutt, R C

    2014-01-01

    This paper presents a detailed analysis of two-armed spiral structure in a sample of galax- ies from the Spitzer Infrared Nearby Galaxies Survey (SINGS), with particular focus on the relationships between the properties of the spiral pattern in the stellar disc and the global struc- ture and environment of the parent galaxies. Following Paper I we have used a combination of Spitzer Space Telescope mid-infrared imaging and visible multi-colour imaging to isolate the spiral pattern in the underlying stellar discs, and we examine the systematic behaviours of the observed amplitudes and shapes (pitch angles) of these spirals. In general, spiral morphology is found to correlate only weakly at best with morphological parameters such as stellar mass, gas fraction, disc/bulge ratio, and vflat. In contrast to weak correlations with galaxy structure a strong link is found between the strength of the spiral arms and tidal forcing from nearby companion galaxies. This appears to support the longstanding suggestion that ei...

  5. Error of Archimedes spiral when applied in linearity compensation

    Science.gov (United States)

    Liu, Ke; Chen, Xiuzheng; Song, Jincheng; Liang, Yajun

    2013-01-01

    The polar coordinates equation of Archimedes spiral is ρ = ρ0 + aθ , also known as uniform speed spiral. In a polar coordinate system, the polar radius ρ has linear relation with polar angle θ . This character could be used for linearity compensation in mechanical engineering, or metrical instrument. For example, it could be used for moment linearity compensation, the common configuration has a pivot axis on the pole, and a thin line wrap around the spiral on the turntable. The gravitation of a suspension used as constant pull, and the level polar radius as force arm, then it generates a liner moment when the Archimedes spiral rotating at uniform speed. But as the polar angle of tangent point on the plumb line changes at any moment, the polar radius on level direction isn't linear with polar angle anymore, and the small error influences the effect of linearity compensation configuration. This paper presented the application of Archimedes spiral in linearity compensation, analyzed the theory error, and deduced the error equation by Mathematic theory. Using computer emulator, educed the precise errors of some dispersed points in common use, and provided according error tabulation. In engineering applications, engineers could consult this error tabulation and correct the points on Archimedes spiral, to realize accurately linearity compensation.

  6. Spontaneous Coronary Artery Dissection following Topical Hormone Replacement Therapy

    Directory of Open Access Journals (Sweden)

    Alexander L. Pan

    2012-01-01

    Full Text Available Spontaneous coronary artery dissection is a rare condition, usually presenting as an acute coronary syndrome, and is often seen in states associated with high systemic estrogen levels such as pregnancy or oral contraceptive use. While topical hormonal replacement therapy may result in increased estrogen levels similar to those documented with oral contraceptive use, there are no reported cases of spontaneous coronary dissection with topical hormonal replacement therapy. We describe a 53-year-old female who developed two spontaneous coronary dissections while on topical hormonal replacement therapy. The patient had no other risk factors for coronary dissection. After withdrawal from topical hormonal therapy, our patient has done well and has not had recurrent coronary artery dissections over a one-year follow-up period. The potential contributory role of topical hormonal therapy as a cause of spontaneous coronary dissection should be recognized.

  7. Metabolic signature of electrosurgical liver dissection.

    Directory of Open Access Journals (Sweden)

    Witigo von Schönfels

    Full Text Available BACKGROUND AND AIMS: High frequency electrosurgery has a key role in the broadening application of liver surgery. Its molecular signature, i.e. the metabolites evolving from electrocauterization which may inhibit hepatic wound healing, have not been systematically studied. METHODS: Human liver samples were thus obtained during surgery before and after electrosurgical dissection and subjected to a two-stage metabolomic screening experiment (discovery sample: N = 18, replication sample: N = 20 using gas chromatography/mass spectrometry. RESULTS: In a set of 208 chemically defined metabolites, electrosurgical dissection lead to a distinct metabolic signature resulting in a separation in the first two dimensions of a principal components analysis. Six metabolites including glycolic acid, azelaic acid, 2-n-pentylfuran, dihydroactinidiolide, 2-butenal and n-pentanal were consistently increased after electrosurgery meeting the discovery (p<2.0 × 10(-4 and the replication thresholds (p<3.5 × 10(-3. Azelaic acid, a lipid peroxidation product from the fragmentation of abundant sn-2 linoleoyl residues, was most abundant and increased 8.1-fold after electrosurgical liver dissection (preplication = 1.6 × 10(-4. The corresponding phospholipid hexadecyl azelaoyl glycerophosphocholine inhibited wound healing and tissue remodelling in scratch- and proliferation assays of hepatic stellate cells and cholangiocytes, and caused apoptosis dose-dependently in vitro, which may explain in part the tissue damage due to electrosurgery. CONCLUSION: Hepatic electrosurgery generates a metabolic signature with characteristic lipid peroxidation products. Among these, azelaic acid shows a dose-dependent toxicity in liver cells and inhibits wound healing. These observations potentially pave the way for pharmacological intervention prior liver surgery to modify the metabolic response and prevent postoperative complications.

  8. Contemporary Management of Acute Type B Dissection.

    Science.gov (United States)

    Scott, A J; Bicknell, C D

    2016-03-01

    Growing confidence in thoracic endovascular aortic repair (TEVAR) for the management of acute type B aortic dissection has resulted in controversies regarding optimum patient selection and the timing of intervention. In this review a clinical vignette to present a practical perspective on the contemporary management of acute type B dissection (ABAD) in a specialist vascular centre with particular focus on areas of debate is used. This is a narrative clinical review. Aggressive anti-impulse therapy is the cornerstone of management of all patients with ABAD. However, 20-30% of patients develop complicated ABAD defined by the presence of malperfusion syndromes, acute aortic dilatation, dissection extension, or persistent pain and hypotension. These complicated patients typically require intervention, and non-randomised series suggest TEVAR to be an effective alternative to open repair with a lower morbidity. There is considerable interest and controversy surrounding the use of TEVAR in uncomplicated ABAD patients for whom the intervention-free survival at 6 years is less than 50% for patients managed with anti-impulse therapy. Data regarding this question are sparse, but two randomised trials (ADSORB and INSTEAD) both demonstrated a higher rate of favourable aortic remodelling in patients managed with TEVAR than medical therapy alone. However, it is unclear whether this positive remodelling translates into a reduction in long-term mortality sufficient to balance the early perioperative hazards of endografting. Despite increasing adeptness at endovascular stenting, the long-term outcomes of patients with ABAD leave significant room for improvement. In particular, the optimum management of patients with uncomplicated disease is unclear and guidance from trials powered for long-term mortality is awaited. Until then, the principals of management of ABAD remain aggressive medical therapy for all patients, with TEVAR primarily reserved for those who develop complications

  9. [Internal carotid artery dissection after laparoscopic surgery].

    Science.gov (United States)

    Martín-Mateos, Esperanza; Gómez-Ríos, Manuel Ángel; Freire-Vila, Enrique

    2017-05-22

    Headache is a common symptom in the postoperative period and may be attributable to, dehydration, sleep deprivation, intentional or inadvertent dural puncture during a neuraxial anesthesia technique, from an inhaled anesthetic agent, or from specific surgical procedures, among other etiologies. However, more serious, uncommon and life-threatening conditions as carotid artery dissection can be associated with severe neurologic sequelae in otherwise young, healthy patients. For these reasons, clinicians involved with postoperative patients should be familiar with the presentation and management strategies for this complication. Copyright © 2017. Publicado por Elsevier Editora Ltda.

  10. Spontaneous Coronary Artery Dissection: Case Report Review of the Literature

    Directory of Open Access Journals (Sweden)

    Kemal Karaağaç

    2013-03-01

    Full Text Available Spontaneous coronary artery dissection is a rare cause of acute coronary syndrome with a high risk of mortality. The clinical presentation is similar to the atherosclerotic coronary artery disease. The diagnosis is usually made by coronary angiography. Spontaneous coronary artery dissection is more common in women than men. Fast and accurate diagnosis and treatment of spontaneous coronary artery dissection patients improves survival. Therapeutic options include surgery, percutaneous coronary intervention and medical therapy.

  11. Analytical modeling of orthogonal spiral structures

    Science.gov (United States)

    Santos, Auteliano A.; Hobeck, Jared D.; Inman, Daniel J.

    2016-11-01

    This paper presents the analytical modeling of orthogonal spiral structures (OSS), a promising option for small-scale energy harvesting applications. This unique multi-beam structure is analyzed using a distributed parameter approach with Euler-Bernoulli assumptions. First, an aluminum substrate is evaluated to determine if the proposed design can be used to capture vibration energy in the desired frequency range using a twelve beam OSS. Finite element calculations are used to validate the analytical model. This model is then modified to include the electromechanical effects of a piezoelectric layer added to the aluminum substrate. Lastly, the effects of the beam width and the number of beams is analyzed for a particular surface area of the OSS. Results show that increasing the number of beams causes a reduction in the first natural frequency. From those results, it is possible to conclude that OSS can be used as an alternative to current energy harvesting systems for MEMS applications, allowing the capture of environmental energy in the frequency range of common mechanical systems.

  12. BVRI Surface Photometry of Isolated Spiral Galaxies

    CERN Document Server

    Hernandez-Toledo, H; Avila-Reese, V

    2007-01-01

    A release of multicolor broad band (BVRI) photometry for a subsample of 44 isolated spirals drawn from the Catalogue of Isolated Galaxies (CIG) is presented. Total magnitudes and colors at various circular apertures, as well as some global structural/morphological parameters are estimated. Morphology is reevaluated through optical and sharp/filtered R band images, (B-I) color index maps, and archive near-IR JHK images from the Two-Micron Survey. The CAS structural parameters (Concentration, Asymmetry, and Clumpiness) were calculated from the images in each one of the bands. The fraction of galaxies with well identified optical/near-IR bars (SB) is 63%, while a 17% more shows evidence of weak or suspected bars (SAB). The sample average value of the maximum bar ellipticity is 0.4. Half of the galaxies in the sample shows rings. We identify two candidates for isolated galaxies with disturbed morphology. The structural CAS parameters change with the observed band, and the tendencies they follow with the morpholog...

  13. Spiralizations and tropisms in Arabidopsis roots.

    Science.gov (United States)

    Migliaccio, F; Piconese, S

    2001-12-01

    When Arabidopsis seedlings are grown on a hard-agar plate, their primary roots show characteristic spiralling movements, apparent as waves, coils and torsions, together with a slanting toward the right-hand side. All these movements are believed to be the result of three different processes acting on the roots: circumnutation, positive gravitropism and negative thigmotropism. The basic movement of the roots is described as that of a growing right-handed helix, which, because of the root tip hitting the agar plate, is continuously switched from the right-hand to the left-hand of the growth direction, and vice versa. This movement also produces a slanting root-growth direction toward the right-hand because of the incomplete waves made by the right-handed root to the left-hand. By contrast, the torsions seen in the coils and waves are interpreted as artefacts that form as an adaptation of the three-dimensional root helix to the flat two-dimensional agar surface.

  14. Lopsided spiral galaxies: evidence for gas accretion

    CERN Document Server

    Bournaud, F; Jog, C J; Puerari, I

    2005-01-01

    We quantify the degree of lopsidedness for a sample of 149 galaxies observed in the near-infrared from the OSUBGS sample, and try to explain the physical origin for the observed disk lopsidedness. We confirm previous studies, but now for a larger sample, that a large fraction of galaxies show significant lopsidedness in their stellar disks, measured as the Fourier amplitude of the m=1 component, normalised to the average or m=0 component, in the surface density. Late-type galaxies are found to be more lopsided, while the presence of m=2 spiral arms and bars is correlated. The m=1 amplitude is found to be uncorrelated with the tidal forces acting on a galaxy via nearby companions. Numerical simulations are carried out to study the generation of m=1 via different processes: galaxy tidal encounters, galaxy mergers, and external gas accretion and subsequent star formation. The simulations show that galaxy interactions and mergers can trigger strong lopsidedness, but do not explain several independent statistical ...

  15. Background Music in the Dissection Laboratory: Impact on Stress Associated with the Dissection Experience

    Science.gov (United States)

    Anyanwu, Emeka G.

    2015-01-01

    Notable challenges, such as mental distress, boredom, negative moods, and attitudes, have been associated with learning in the cadaver dissection laboratory (CDL). The ability of background music (BM) to enhance the cognitive abilities of students is well documented. The present study was designed to investigate the impact of BM in the CDL and on…

  16. Doing Dissections Differently: A Structured, Peer-Assisted Learning Approach to Maximizing Learning in Dissections

    Science.gov (United States)

    Hall, Emma R.; Davis, Rachel C.; Weller, Renate; Powney, Sonya; Williams, Sarah B.

    2013-01-01

    Areas of difficulty faced by our veterinary medicine students, with respect to their learning in dissection classes, were identified. These challenges were both general adult-learning related and specific to the discipline of anatomy. Our aim was to design, implement, and evaluate a modified reciprocal peer-assisted/team-based learning…

  17. Background Music in the Dissection Laboratory: Impact on Stress Associated with the Dissection Experience

    Science.gov (United States)

    Anyanwu, Emeka G.

    2015-01-01

    Notable challenges, such as mental distress, boredom, negative moods, and attitudes, have been associated with learning in the cadaver dissection laboratory (CDL). The ability of background music (BM) to enhance the cognitive abilities of students is well documented. The present study was designed to investigate the impact of BM in the CDL and on…

  18. Doing Dissections Differently: A Structured, Peer-Assisted Learning Approach to Maximizing Learning in Dissections

    Science.gov (United States)

    Hall, Emma R.; Davis, Rachel C.; Weller, Renate; Powney, Sonya; Williams, Sarah B.

    2013-01-01

    Areas of difficulty faced by our veterinary medicine students, with respect to their learning in dissection classes, were identified. These challenges were both general adult-learning related and specific to the discipline of anatomy. Our aim was to design, implement, and evaluate a modified reciprocal peer-assisted/team-based learning…

  19. Treatment of infrarenal abdominal aortic dissection concomitant with an aneurysm

    Institute of Scientific and Technical Information of China (English)

    WANG Li-xin; ZHU Ting; FU Wei-guo; WANG Yu-qi; XI Xun; GUO Da-qiao; CHEN Bin; JIANG Jun-hao; YANG Ju; SHI Zhen-yu

    2007-01-01

    @@ Aortic dissection occurs when layers of the aortic walls are separated by the blood flow through an intimal tear. Dissection of the aorta most frequently originates in the ascending aorta (70%), followed by the descending aorta (22%), the aortic arch (7%) and the abdominal aorta (1/%).1 The dissection limited to the abdominal aorta is rare.2 An isolated abdominal aortic dissection (IAAD) concomitant with an abdominal aortic aneurysm (AAA) is uncommon. We present here one patient with IAAD and AAA treated by endovascular therapy.

  20. Stellar Orbital Studies in Normal Spiral Galaxies II: Restrictions to Structural and Dynamical parameters on Spiral Arms

    CERN Document Server

    Pérez-Villegas, Angeles; Moreno, Edmundo

    2015-01-01

    Making use of a set of detailed potential models for normal spiral galaxies, we analyze the disk stellar orbital dynamics as the structural and dynamical parameters of the spiral arms (mass, pattern speed and pitch angle) are gradually modified. With this comprehensive study of ordered and chaotic behavior, we constructed an assemblage of orbitally supported galactic models and plausible parameters for orbitally self-consistent spiral arms models. We find that, to maintain orbital support for the spiral arms, the spiral arm mass, M$_{sp}$, must decrease with the increase of the pitch angle, $i$; if $i$ is smaller than $\\sim10\\deg$, M$_{sp}$ can be as large as $\\sim7\\%$, $\\sim6\\%$, $\\sim5\\%$ of the disk mass, for Sa, Sb, and Sc galaxies, respectively. If $i$ increases up to $\\sim25\\deg$, the maximum M$_{sp}$ is $\\sim1\\%$ of the disk mass independently in this case of morphological type. For values larger than these limits, spiral arms would likely act as transient features. Regarding the limits posed by extrem...

  1. Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51

    Science.gov (United States)

    Egusa, Fumi; Mentuch Cooper, Erin; Koda, Jin; Baba, Junichi

    2017-02-01

    Theoretical studies on the response of interstellar gas to a gravitational potential disc with a quasi-stationary spiral arm pattern suggest that the gas experiences a sudden compression due to standing shock waves at spiral arms. This mechanism, called a galactic shock wave, predicts that gas spiral arms move from downstream to upstream of stellar arms with increasing radius inside a corotation radius. In order to investigate if this mechanism is at work in the grand-design spiral galaxy M51, we have measured azimuthal offsets between the peaks of stellar mass and gas mass distributions in its two spiral arms. The stellar mass distribution is created by the spatially resolved spectral energy distribution fitting to optical and near-infrared images, while the gas mass distribution is obtained by high-resolution CO and H I data. For the inner region (r ≤ 150 arcsec), we find that one arm is consistent with the galactic shock while the other is not. For the outer region, results are less certain due to the narrower range of offset values, the weakness of stellar arms, and the smaller number of successful offset measurements. The results suggest that the nature of two inner spiral arms is different, which is likely due to an interaction with the companion galaxy.

  2. The Effect of a Prior Dissection Simulation on Middle School Students' Dissection Performance and Understanding of the Anatomy and Morphology of the Frog

    Science.gov (United States)

    Akpan, Joseph Paul; Andre, Thomas

    1999-06-01

    Science teachers, school administrators, educators, and the scientific community are faced with ethical controversies over animal dissection in classrooms. Simulation has been proposed as a way of dealing with this issue. One intriguing previous finding was that use of an interactive videodisc dissection facilitated performance on a subsequent actual dissection. This study examined the prior use of simulation of frog dissection in improving students' actual dissection performance and learning of frog anatomy and morphology. There were three experimental conditions: simulation before dissection (SBD); dissection before simulation (DBS); or dissection-only (DO). Results of the study indicated that students receiving SBD performed significantly better than students receiving DBS or DO on both actual dissection and knowledge of the anatomy and morphology. Students' attitudes toward the use of animals for dissection did not change significantly from pretest to posttest and did not interact with treatment. The genders did not differ in achievement, but males were more favorable towards dissection and computers than were females.

  3. Pancreaticoduodenectomy with early superior mesenteric artery dissection

    Institute of Scientific and Technical Information of China (English)

    Yu-Fei Xu; Zuo-Jin Liu; Jian-Ping Gong

    2010-01-01

    BACKGROUND: Pancreatic adenocarcinoma remains the fourth leading cause of cancer-related death and is one of the most aggressive human tumors. At present, surgical resection is the only potentially curative treatment. Early neck division is inadequate when invasion of the superior mesenteric artery (SMA) is suspected or in cases of replaced or accessory right hepatic artery. Malignant periampullary tumors often invade retroperitoneal peripancreatic tissues and a positive resection margin is associated with a poor long-term survival. DATA SOURCES: English-language medical databases, PubMed, ELSEVIER and SPRINGERLINK, were searched for articles on"posterior approach pancreaticoduodenectomy","superior mesenteric artery ifrst approach", "retroperitoneal tissue","hanging maneuver", and related topics. RESULTS:The modiifcation allowed the surgeon to early identify the nonresectability of a replaced right hepatic artery if present, enabling complete dissection of the right side of the SMA and portal vein as well as complete excision of the retroportal pancreatic lamina. CONCLUSION: Pancreaticoduodenectomy with early retro-pancreatic dissection is a useful and safe technical variant, which is indicated for the improvement of the safety and curative effect of the procedure.

  4. Laser versus dissection technique of tonsillectomy.

    Science.gov (United States)

    Ishlah, L Wan; Fahmi, A M; Srinovianti, N

    2005-03-01

    Tonsillectomy is the single most common operation performed in Ear Nose and Throat Department. Various methods of tonsillectomy have been practiced over the century aimed at reducing or eliminating intraoperative and postoperative morbidity. Due to various blood supplies received, intraoperative bleeding is the most difficult problem and securing it is time-consuming. The time taken to control the bleeding would invariably determine the length of operation. Common postoperative complications are bleeding and pain. This study evaluated the operative time, intraoperative blood loss, postoperative pain and other postoperative complications of tonsillectomy performed by laser as compared to conventional dissection technique. This is a prospective randomized study whereby sixty patients were divided into two groups of equal number. In one group, the tonsillectomy performed by laser and in the other group the tonsillectomy performed by conventional dissection technique. Operative time and amount of blood loss is significantly reduced in the laser group. Total postoperative pain and post operative complications were not significantly different between the two groups. Tonsillectomy by using laser have shown less intraoperative bleeding and shortened the operative time. In the hospital where laser machine and expertise are available, it is justifiable to use this technique as effective method of performing tonsillectomy.

  5. Spiral structures and regularities in magnetic field variations and auroras

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    2012-02-01

    Full Text Available The conception of spiral shaped precipitation regions, where solar corpuscles penetrate the upper atmosphere, was introduced into geophysics by C. Störmer and K. Birkeland at the beginning of the last century. Later, in the course of the XX-th century, spiral distributions were disclosed and studied in various geophysical phenomena. Most attention was devoted to spiral shapes in the analysis of regularities pertaining to the geomagnetic activity and auroras.

    We review the historical succession of perceptions about the number and positions of spiral shapes, that characterize the spatial-temporal distribution of magnetic disturbances. We describe the processes in the upper atmosphere, which are responsible for the appearance of spiral patterns. We considered the zones of maximal aurora frequency and of maximal particle precipitation intensity, as offered in the literature, in their connection with the spirals.

    We discuss the current system model, that is closely related to the spirals and that appears to be the source for geomagnetic field variations during magnetospheric substorms and storms. The currents in ionosphere and magnetosphere constitute together with field-aligned (along the geomagnetic field lines currents (FACs a common 3-D current system. At ionospheric heights, the westward and eastward electrojets represent characteristic elements of the current system. The westward electrojet covers the longitudinal range from the morning to the evening hours, while the eastward electrojet ranges from afternoon to near-midnight hours. The polar electrojet is positioned in the dayside sector at cusp latitudes. All these electrojets map along the magnetic field lines to certain plasma structures in the near-Earth space. The first spiral distribution of auroras was found based on observations in Antarctica for the nighttime-evening sector (N-spiral, and later in the nighttime-evening (N-spiral and morning (M-spiral sectors both in

  6. Spiral Wave Generation in a Vortex Electric Field

    Institute of Scientific and Technical Information of China (English)

    YUAN Xiao-Ping; CHEN Jiang-Xing; ZHAO Ye-Hua; LOU Qin; WANG Lu-Lu; SIIEN Qian

    2011-01-01

    The effect of a vortical electric field on nonlinear patterns in excitable media is studied. When an appropriate vortex electric field is applied, the system exhibits pattern transition from chemical turbulence to spiral waves, which possess the same chtality as the vortex electric field. The underlying mechanism of this is discussed. We also show the meandering behavior of a spiral under the taming of a vortex electric field. The results obtained here may contribute to control strategies of patterns on surface reaction.%The effect of a vortical electric field on nonlinear patterns in excitable media is studied.When an appropriate vortex electric field is applied,the system exhibits pattern transition from chemical turbulence to spiral waves,which possess the same chirality as the vortex electric field.The underlying mechanism of this is discussed.We also show the meandering behavior of a spiral under the taming of a vortex electric field.The results obtained here may contribute to control strategies of patterns on surface reaction.Spiral waves are one of the most common and widely studied patterns in nature.They appear in hydrodynamic systems,chemical reactions and a large variety of biological,chemical and physical systems.[1-5] Much attention has been paid to their rich nonlinear dynamics,as well as potential applications in various biological or physiological systems,since the emergence and instability of spirals usually lead to abnormal states,for example in cardiac arrythmia[6,7] and epilepsy[8].Much research has been carried out in studying pattern formations in catalytic CO oxidation on Pt(110),[9-11] because they provide practical utilization in industry.A rich variety of spatiotemporal patterns,including travelling pulses,standing waves,target patterns,spiral waves and chemical turbulence have been observed in this system.[12-16

  7. Unstable Dynamical Properties of Spiral Cloud Bands in Tropical Cyclones

    Institute of Scientific and Technical Information of China (English)

    HUANG Hong; ZHANG Ming

    2009-01-01

    A nondivergent barotropic model (Model 1) and a barotropic primitive equation vortex model (Model 2) are linearized respectively in this paper. Then their perturbation wave spectrums are computed with a normal mode approach to study the instability problem on an appointed tropical cyclone (TC)-like vortex, thereby, the dynamic instability properties of spiral cloud bands of TCs are discussed. The results show that the unstable mode of both models exhibits a spiral band-like structure that propagates away from the vortex outside the radius of maximum winds. The discrete modal instability of the pure vortex Rossby wave can account for the generation of the eyewall and the inner spiral band. The unstable mode in Model 2 has three parts, i.e., eyewall, inner and outer spiral bands. This mode can be interpreted as a mixed vortex Rossby-inertia gravitational wave. The unbalanced property of the wave outside the stagnation radius of the vortex Rossby wave is one of the important reasons for the formation of the outer spiral band in TCs. Accordingly, the outer spiral band can be identified to possess properties of an inertial-gravitational wave.When the formation of unstable inner and outer spiral bands is studied, a barotropic vortex model shall be used. In this model, the most unstable perturbation bears the attributes of either the vortex Rossby wave or the inertial-gravitational wave, depending on the vortex radius. So such perturbations shall be viewed as an unbalanced and unstable mixed wave of these two kinds of waves.

  8. Negative spiral CT in acute pulmonary embolism

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, T.; Olausson, A. [Karolinska Hospital, Stockholm (Sweden). Dept. of Thoracic Radiology; Johnsson, H. [Karolinska Hospital, Stockholm (Sweden). Dept. of Internal Medicine; Nyman, U. [County Hospital, Trelleborg (Sweden). Dept. of Radiology; Aspelin, P. [Huddinge Univ. Hospital (Sweden). Dept. of Radiology

    2002-09-01

    Purpose: To retrospectively evaluate the clinical outcome of non-anticoagulated patients with clinically suspected acute pulmonary embolism (PE) and no symptoms or signs of deep venous thrombosis (DVT) following a negative contrast medium-enhanced spiral CT of the pulmonary arteries (s-CTPA). Material and Methods: During a 24-month period, 739 of 751 patients underwent s-CTPA with acceptable diagnostic quality for clinically suspected acute PE. All patients who had a CT study not positive for PE were followed up with a questionnaire, a telephone interview and review of all medical reports, including autopsies and death certificates for any episodes of venous thromboembolism (VTE) during a 3-month period. Results: PE was diagnosed in 158 patients. Of the remaining 581 patients with a negative s-CTPA, 45 patients were lost to follow-up. 88 patients were excluded because of anticoagulation treatment (cardiac disorder n=32, chronic VTE or acute symptomatic DVT n=31, PE diagnosed at pulmonary angiography n=1, thrombus prophylaxis during diagnostic work-up or other reasons than VTE n=24) and 7 patients undergoing lower extremity venous studies because of symptoms of DVT (all negative). Thus, 441 patients with a negative s-CTPA and no DVT symptoms, venous studies or anticoagulant treatment constituted the follow-up cohort. Four of these patients had proven VTE (all PE) during the 3-month follow-up period. Two of the PE episodes contributed to the patient's death. Conclusion: Patients with clinically suspected acute PE, no symptoms or signs of DVT and a negative single slice s-CTPA using 3-5 mm collimation, may safely be left without anticoagulation treatment unless they are critically ill, have a limited cardiopulmonary reserve and/or if a high clinical suspicion remains.

  9. Stabilization of spiral wave and turbulence in the excitable media using parameter perturbation scheme

    Institute of Scientific and Technical Information of China (English)

    Ma Jun; Wang Chun-Ni; Jin Wu-Yin; Li Yan-Long; Pu Zhong-Sheng

    2008-01-01

    This paper proposes a scheme of parameter perturbation to suppress the stable rotating spiral wave, meandering spiral wave and turbulence in the excitable media, which is described by the modified Fitzhugh-Nagumo (MFHN) model. The controllable parameter in the MFHN model is perturbed with a weak pulse and the pulse period is decided by the rotating period of the spiral wave approximatively. It is confirmed that the spiral wave and spiral turbulence can be suppressed greatly. Drift and instability of spiral wave can be observed in the numerical simulation tests before the whole media become homogeneous finally.

  10. Dissection of the adult zebrafish kidney.

    Science.gov (United States)

    Gerlach, Gary F; Schrader, Lauran N; Wingert, Rebecca A

    2011-08-29

    Researchers working in the burgeoning field of adult stem cell biology seek to understand the signals that regulate the behavior and function of stem cells during normal homeostasis and disease states. The understanding of adult stem cells has broad reaching implications for the future of regenerative medicine. For example, better knowledge about adult stem cell biology can facilitate the design of therapeutic strategies in which organs are triggered to heal themselves or even the creation of methods for growing organs in vitro that can be transplanted into humans. The zebrafish has become a powerful animal model for the study of vertebrate cell biology. There has been extensive documentation and analysis of embryonic development in the zebrafish. Only recently have scientists sought to document adult anatomy and surgical dissection techniques, as there has been a progressive movement within the zebrafish community to broaden the applications of this research organism to adult studies. For example, there are expanding interests in using zebrafish to investigate the biology of adult stem cell populations and make sophisticated adult models of diseases such as cancer. Historically, isolation of the zebrafish adult kidney has been instrumental for studying hematopoiesis, as the kidney is the anatomical location of blood cell production in fish. The kidney is composed of nephron functional units found in arborized arrangements, surrounded by hematopoietic tissue that is dispersed throughout the intervening spaces. The hematopoietic component consists of hematopoietic stem cells (HSCs) and their progeny that inhabit the kidney until they terminally differentiate. In addition, it is now appreciated that a group of renal stem/progenitor cells (RPCs) also inhabit the zebrafish kidney organ and enable both kidney regeneration and growth, as observed in other fish species. In light of this new discovery, the zebrafish kidney is one organ that houses the location of two

  11. SMAD2 Mutations Are Associated with Arterial Aneurysms and Dissections

    NARCIS (Netherlands)

    Micha, D.; Guo, D.C.; Hilhorst-Hofstee, Y.; Kooten, F. van; Atmaja, D.; Overwater, E.; Cayami, F.K.; Regalado, E.S.; Uffelen, R. van; Venselaar, H.; Faradz, S.M.H.; Vriend, G.; Weiss, M.M.; Sistermans, E.A.; Maugeri, A.; Milewicz, D.M.; Pals, G.; Dijk, F.S. Van

    2015-01-01

    We report three families with arterial aneurysms and dissections in which variants predicted to be pathogenic were identified in SMAD2. Moreover, one variant occurred de novo in a proband with unaffected parents. SMAD2 is a strong candidate gene for arterial aneurysms and dissections given its role

  12. Cardiac tamponade – presentation of type A aortic dissection

    Directory of Open Access Journals (Sweden)

    Opeyemi Fadahunsi

    2014-11-01

    Full Text Available Acute aortic dissection usually presents with severe chest and/or back pain but may have a varied presentation ranging from syncope, stroke, and heart failure to shock or tamponade. We present classic chest computed tomography images of a case of type A aortic dissection presenting with cardiac tamponade.

  13. Spontaneous carotid artery dissection causing a juvenile cerebral infarction

    Energy Technology Data Exchange (ETDEWEB)

    Trattnig, S.; Huebsch, P.; Schindler, E.

    1988-11-01

    The case of a 19-year-old patient is presented who was admitted with aphasia and hemiparesis due to basal ganglia infarction as a result of spontaneous dissection of the internal carotid artery. The difficulties in diagnosing this disease with CT and MRI in the acute stage are demonstrated. Angiography is still imperative in order to ascertain that a carotid dissection has occurred.

  14. Dissection Videos Do Not Improve Anatomy Examination Scores

    Science.gov (United States)

    Mahmud, Waqas; Hyder, Omar; Butt, Jamaal; Aftab, Arsalan

    2011-01-01

    In this quasi-experimental study, we describe the effect of showing dissection videos on first-year medical students' performance in terms of test scores during a gross anatomy course. We also surveyed students' perception regarding the showing of dissection videos. Two hundred eighty-seven first-year medical students at Rawalpindi Medical College…

  15. An alternate dissection approach to the female urogenital triangle.

    Science.gov (United States)

    Hall, Margaret I; Walters, Linda M

    2013-09-01

    Traditional dissections of the female urogenital (UG) triangle can lead to early destruction of the erectile tissues, associated musculature, and neurovascular structures. Here, we present an alternate dissection of the female UG triangle. Rather than begin the female UG triangle dissection with the fatty tissue of the labia majora, we utilize an early identification of the suspensory ligament of the clitoris to organize the dissection. The suspensory ligament leads to the body of the clitoris, which can be palpated from distal to proximal to find the crura of the clitoris with overlying ischiocavernosus muscles. Once the crura have been defined, the bulbs of the vestibule with overlying bulbospongiosus muscles can be palpated medially and posteriorly. This dissection approach results in a clean dissection that well demonstrates homologies between male and female external genitalia. Through the use of this method, most student dissection attempts are able to demonstrate the erectile tissues and associated musculature that comprise the female UG triangle. This technique can also be used for male UG triangle dissections, encouraging identification of male and female homologies. Copyright © 2013 Wiley Periodicals, Inc.

  16. Dissection Videos Do Not Improve Anatomy Examination Scores

    Science.gov (United States)

    Mahmud, Waqas; Hyder, Omar; Butt, Jamaal; Aftab, Arsalan

    2011-01-01

    In this quasi-experimental study, we describe the effect of showing dissection videos on first-year medical students' performance in terms of test scores during a gross anatomy course. We also surveyed students' perception regarding the showing of dissection videos. Two hundred eighty-seven first-year medical students at Rawalpindi Medical College…

  17. Outcomes of a Rotational Dissection System in Gross Anatomy

    Science.gov (United States)

    Marshak, David W.; Oakes, Joanne; Hsieh, Pei-Hsuan; Chuang, Alice Z.; Cleary, Leonard J.

    2015-01-01

    At the University of Texas Houston Medical School, a rotational dissection system was introduced to improve coordination between the Gross Anatomy and the Introduction to Clinical Medicine (ICM) courses. Six students were assigned to each cadaver and divided into two teams. For each laboratory, one team was assigned to dissect and the other to…

  18. Student Attitudes toward Cadaveric Dissection at a UK Medical School

    Science.gov (United States)

    Quince, Thelma A.; Barclay, Stephen I. G.; Spear, Michelle; Parker, Richard A.; Wood, Diana F.

    2011-01-01

    A more humanistic approach toward dissection has emerged. However, student attitudes toward this approach are unknown and the influences on such attitudes are little understood. One hundred and fifty-six first-year medical students participated in a study examining firstly, attitudes toward the process of dissection and the personhood of the…

  19. Vibration damping using a spiral acoustic black hole.

    Science.gov (United States)

    Lee, Jae Yeon; Jeon, Wonju

    2017-03-01

    This study starts with a simple question: can the vibration of plates or beams be efficiently reduced using a lightweight structure that occupies a small space? As an efficient technique to damp vibration, the concept of an acoustic black hole (ABH) is adopted with a simple modification of the geometry. The original shape of an ABH is a straight wedge-type profile with power-law thickness, with the reduction of vibration in beams or plates increasing as the length of the ABH increases. However, in real-world applications, there exists an upper bound of the length of an ABH due to space limitations. Therefore, in this study, the authors propose a curvilinear shaped ABH using the simple mathematical geometry of an Archimedean spiral, which allows a uniform gap distance between adjacent baselines of the spiral. In numerical simulations, the damping performance increases as the arc length of the Archimedean spiral increases, regardless of the curvature of the spiral in the mid- and high-frequency ranges. Adding damping material to an ABH can also strongly enhance the damping performance while not significantly increasing the weight. In addition, the radiated sound power of a spiral ABH is similar to that of a standard ABH.

  20. The Onset of Spiral Structure in the Universe

    CERN Document Server

    Elmegreen, Debra Meloy

    2013-01-01

    The onset of spiral structure in galaxies appears to occur between redshifts 1.4 and 1.8 when disks have developed a cool stellar component, rotation dominates over turbulent motions in the gas, and massive clumps become less frequent. During the transition from clumpy to spiral disks, two unusual types of spirals are found in the Hubble Ultra Deep Field that are massive, clumpy and irregular like their predecessor clumpy disks, yet spiral-like or sheared like their descendants. One type is ``woolly'' with massive clumpy arms all over the disk and is brighter than other disk galaxies at the same redshift, while another type has irregular multiple arms with high pitch angles, star formation knots and no inner symmetry like today's multiple-arm galaxies. The common types of spirals seen locally are also present in a redshift range around z~1, namely grand design with two symmetric arms, multiple arm with symmetry in the inner parts and several long, thin arms in the outer parts, and flocculent, with short, irre...

  1. The local spiral structure of the Milky Way.

    Science.gov (United States)

    Xu, Ye; Reid, Mark; Dame, Thomas; Menten, Karl; Sakai, Nobuyuki; Li, Jingjing; Brunthaler, Andreas; Moscadelli, Luca; Zhang, Bo; Zheng, Xingwu

    2016-09-01

    The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star formation near the Local spiral arm of the Milky Way. Combined with previous measurements, these observations reveal that the Local Arm is larger than previously thought, and both its pitch angle and star formation rate are comparable to those of the Galaxy's major spiral arms, such as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the Local Arm extend for a great distance along our line of sight and roughly along the solar orbit. Because of this orientation, these sources cluster both on the sky and in velocity to form the complex and long enigmatic Cygnus X region. We also identify a spur that branches between the Local and Sagittarius spiral arms.

  2. Branch, Spur, and Feather Formation in Spiral Galaxies

    CERN Document Server

    Chakrabarti, S; Shu, F H

    2003-01-01

    We use hydrodynamical simulations to investigate the response of geometrically thin, self-gravitating, singular isothermal disks of gas to imposed rigidly rotating spiral potentials. By minimizing reflection-induced feedback from boundaries, and by restricting our attention to models where the swing parameter $X sim 10$, we minimize the swing amplification of global normal modes even in models where Toomre's $Q_g sim 1-2$ in the gas disk. We perform two classes of simulations: short-term ones over a few galactic revolutions where the background spiral forcing is large, and long-term ones over many galactic revolutions where the spiral forcing is considerably smaller. In both classes of simulations, the initial response of the gas disk is smooth and mimics the driving spiral field. At late times, many of the models evince substructure akin to the so-called branches, spurs, and feathers observed in real spiral galaxies. We comment on the parts played respectively by ultraharmonic resonances, reflection off inte...

  3. Environment Dependence of Disk Morphology of Spiral Galaxies

    CERN Document Server

    Ann, H B

    2014-01-01

    We analyze the dependence of disk morphology (arm class, Hubble type, bar type) of nearby spiral galaxies on the galaxy environment by using local background density ($\\Sigma_{n}$), projected distance ($r_{p}$), and tidal index ($TI$) as measures of the environment. There is a strong dependence of arm class and Hubble type on the galaxy environment, while the bar type exhibits a weak dependence with a high frequency of SB galaxies in high density regions. Grand design fractions and early-type fractions increase with increasing $\\Sigma_{n}$, $1/r_{p}$, and $TI$, while fractions of flocculent spirals and late-type spirals decrease. Multiple-arm and intermediate-type spirals exhibit nearly constant fractions with weak trends similar to grand design and early-type spirals. While bar types show only a marginal dependence on $\\Sigma_{n}$, they show a fairly clear dependence on $r_{p}$ with a high frequency of SB galaxies at small $r_{p}$. The arm class also exhibits a stronger correlation with $r_{p}$ than $\\Sigma_...

  4. Influence of spiral framework on nonlinear optical materials.

    Science.gov (United States)

    Hu, Yang-Yang; Sun, Shi-Ling; Tian, Wen-Tao; Tian, Wei Quan; Xu, Hong-Liang; Su, Zhong-Min

    2014-04-04

    A series of spiral donor-π-acceptor frameworks (i.e. 2-2, 3-3, 4-4, and 5-5) based on 4-nitrophenyldiphenylamine with π-conjugated linear acenes (naphthalenes, anthracenes, tetracenes, and pentacenes) serving as the electron donor and nitro (NO2 ) groups serving as the electron acceptor were designed to investigate the relationships between the nonlinear optical (NLO) responses and the spirality in the frameworks. A parameter denoted as D was defined to describe the extent of the spiral framework. The D value reached its maximum if the number of NO2 groups was equal to the number of fused benzene rings contained in the linear acene. A longer 4-nitrophenyldiphenylamine chain led to a larger D value and, further, to a larger first hyperpolarizability. Different from traditional NLO materials with charge transfer occurring in the one-dimensional direction, charge transfer in 2-2, 3-3, 4-4, and 5-5 occur in three-dimensional directions due to the attractive spiral frameworks, and this is of great importance in the design of NLO materials. The origin of such an enhancement in the NLO properties of these spiral frameworks was explained with the aid of molecular orbital analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Dynamics of Non-Steady Spiral Arms in Disk Galaxies

    CERN Document Server

    Baba, Junichi; Wada, Keiichi

    2012-01-01

    In order to understand the physical mechanisms underlying non-steady stellar spiral arms in disk galaxies, we analyzed the growing and damping phases of their spiral arms using three-dimensional $N$-body simulations. We confirmed that the spiral arms are formed due to a swing amplification mechanism that reinforces density enhancement as a seeded wake. In the damping phase, the Coriolis force exerted on a portion of the arm surpasses the gravitational force that acts to shrink the portion. Consequently, the stars in the portion escape from the arm, and subsequently they form a new arm at a different location. The time-dependent nature of the spiral arms are originated in the continual repetition of this non-linear phenomenon. Since a spiral arm does not rigidly rotate, but follows the galactic differential rotation, the stars in the arm rotate at almost the same rate as the arm. In other words, every single position in the arm can be regarded as the co-rotation point. Due to interaction with their host arms, ...

  6. The Discovery of a Low-Luminosity SPIRAL DRAGN

    CERN Document Server

    Mulcahy, D D; Mitsuishi, I; Scaife, A M M; Clarke, A O; Babazaki, Y; Kobayashi, H; Suganuma, R; Matsumoto, H; Tawara, Y

    2016-01-01

    Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only $\\sim 5$ cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75 M$_{\\odot}$yr$^{-1}$, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of $L_{\\rm 1.4GHz}$ = 1.12$\\times$10$^{22}$...

  7. Spirals in protoplanetary disks from photon travel time

    Science.gov (United States)

    Kama, M.; Pinilla, P.; Heays, A. N.

    2016-09-01

    Spiral structures are a common feature in scattered-light images of protoplanetary disks, and of great interest as possible tracers of the presence of planets. However, other mechanisms have been put forward to explain them, including self-gravity, disk-envelope interactions, and dead zone boundaries. These mechanisms explain many spirals very well, but are unable to easily account for very loosely wound spirals and single spiral arms. We study the effect of light travel time on the shape of a shadow cast by a clump orbiting close (within ~ 1 au) of the central star, where there can be significant orbital motion during the light travel time from the clump to the outer disk and then to the sky plane. This delay in light rays reaching the sky plane gives rise to a variety of spiral- and arc-shaped shadows, which we describe with a general fitting formula for a flared, inclined disk. The three movies are available at http://www.aanda.org

  8. Magnetic field evolution and reversals in spiral galaxies

    CERN Document Server

    Dobbs, C L; Pettitt, A R; Bate, M R; Tricco, T

    2016-01-01

    We study the evolution of galactic magnetic fields using 3D smoothed particle magnetohydrodynamics (SPMHD) simulations of galaxies with an imposed spiral potential. We consider the appearance of reversals of the field, and amplification of the field. We find magnetic field reversals occur when the velocity jump across the spiral shock is above $\\approx$20km s$^{-1}$, occurring where the velocity change is highest, typically at the inner Lindblad resonance (ILR) in our models. Reversals also occur at corotation, where the direction of the velocity field reverses in the co-rotating frame of a spiral arm. They occur earlier with a stronger amplitude spiral potential, and later or not at all with weaker or no spiral arms. The presence of a reversal at a radii of around 4--6 kpc in our fiducial model is consistent with a reversal identified in the Milky Way, though we caution that alternative Galaxy models could give a similar reversal. We find that relatively high resolution, a few million particles in SPMHD, is ...

  9. Density-Wave Spiral Theories in the 1960s. I

    CERN Document Server

    Pasha, I I

    2004-01-01

    With the arrival of computers, plasma physics and several fresh investigators by the early 1960s, understanding the spiral structure of galaxies entered a new stage of unusually vigorous activity broadly grouped under the umbrella marked "density-wave theory". Paper I starts with acknowledging B. Lindblad, rightly regarded the main father of this whole subject, and then describes the early contributions by Lynden-Bell, Toomre, Hunter and Kalnajs, who had formulated and applied such notions as the stability of flat galaxies, the regenerative spiral phenomenon, the shearing density waves and the global spiral modes. But the foremost enthusiast and proponent of the density-wave picture was undoubtedly C.C. Lin whose 1964 and 1966 papers with Shu, written in support of his working hypothesis of the quasi-stationary wave-mode spiral structure, had a big and immediate impact upon astronomers, at least as a welcome sign that genuine understanding of the spiral phenomenon seemed in some sense to be just around the co...

  10. Guiding Spin Spirals by Local Uniaxial Strain Relief.

    Science.gov (United States)

    Hsu, Pin-Jui; Finco, Aurore; Schmidt, Lorenz; Kubetzka, André; von Bergmann, Kirsten; Wiesendanger, Roland

    2016-01-08

    We report on the influence of uniaxial strain relief on the spin spiral state in the Fe double layer grown on Ir(111). Scanning tunneling microscopy (STM) measurements reveal areas with reconstruction lines resulting from uniaxial strain relief due to the lattice mismatch of Fe and Ir atoms, as well as pseudomorphic strained areas. Magnetic field-dependent spin-polarized STM measurements of the reconstructed Fe double layer reveal cycloidal spin spirals with a period on the nm scale. Globally, the spin spiral wave fronts are guided along symmetry-equivalent [112̅] crystallographic directions of the fcc(111) substrate. On an atomic scale the spin spiral propagation direction is linked to the [001] direction of the bcc(110)-like Fe, leading to a zigzag shaped wave front. The isotropically strained pseudomorphic areas also exhibit a preferred magnetic periodicity on the nm scale but no long-range order. We find that already for local strain relief with a single set of reconstruction lines a strict guiding of the spin spiral is realized.

  11. Prominent spiral arms in the gaseous outer galaxy disks

    CERN Document Server

    Bertin, G

    2009-01-01

    Context: Several spiral galaxies, as beautifully exhibited by the case of NGC 6946, display a prominent large-scale spiral structure in their gaseous outer disk. Such structure is often thought to pose a dynamical puzzle, because grand-design spiral structure is traditionally interpreted as the result of density waves carried mostly in the stellar disk. Aims. Here we argue that the outer spiral arms in the cold gas outside the bright optical disk actually have a natural interpretation as the manifestation of the mechanism that excites grand-design spiral structure in the main, star-dominated body of the disk: the excitation is driven by angular momentum transport to the outer regions, through trailing density waves outside the corotation circle that can penetrate beyond the Outer Lindblad Resonance in the gaseous component of the disk. Methods: Because of conservation of the density wave action, these outgoing waves are likely to become more prominent in the outer disk and eventually reach non-linear amplitud...

  12. Grand Design Spiral Arms in A Young Forming Circumstellar Disk

    CERN Document Server

    Tomida, Kengo; Hosokawa, Takashi; Sakurai, Yuya; Lin, Chia Hui

    2016-01-01

    We study formation and long-term evolution of a circumstellar disk in a collapsing molecular cloud core using a resistive magnetohydrodynamic simulation. While the formed circumstellar disk is initially small, it grows as accretion continues and its radius becomes as large as 200 AUs toward the end of the Class-I phase. A pair of grand-design spiral arms form due to gravitational instability in the disk, and they transfer angular momentum in the highly resistive disk. Although the spiral arms disappear in a few rotations as expected in a classical theory, new spiral arms form recurrently as the disk soon becomes unstable again by gas accretion. Such recurrent spiral arms persist throughout the Class-0 and I phase. We then perform synthetic observations and compare our model with a recent high-resolution observation of a young stellar object Elias 2-27, whose circumstellar disk has grand design spiral arms. We find an excellent agreement between our theoretical model and the observation. Our model suggests tha...

  13. THE COURSE OF DISSECTING ANEURYSM OF THE AORTA

    Directory of Open Access Journals (Sweden)

    N. A. Kosheleva

    2016-01-01

    Full Text Available Research objective. To define features of a course of dissecting aortic aneurysm now.Materials and methods. 11 clinical records of the patients with the established diagnosis of dissecting aortic aneurysm who have come to Regional clinical hospital of Saratov for 2015 are analysed.Results. Along with traditional risk factors, such as the male, existence of arterial hypertension are revealed also additional risk factors, in particular, regular heavy lifting. Gender features in localization of dissecting aortic aneurysm are defined: at men more often of dissecting aortic aneurysm of an aorta is localized in the abdominal aorta, at women in the thoracic region.Conclusions. Additional risk factor of stratification of dissecting aortic aneurysm in the thoracic region at women is the systematic raising of weights.

  14. Transanal total mesorectal excision: dissection tips using 'O's and 'triangles'.

    Science.gov (United States)

    Bernardi, M-P; Bloemendaal, A L A; Albert, M; Whiteford, M; Stevenson, A R L; Hompes, R

    2016-11-01

    Transanal total mesorectal excision (taTME) requires specific technical expertise, as it is often difficult to ascertain the correct dissection plane. Consequently, one can easily enter an incorrect plane, potentially resulting in bleeding (sidewall or presacral vessels), autonomic nerve injury and urethral injury. We aim to demonstrate specific visual features, which may be encountered during surgery and can guide the surgeon to perform the dissection in the correct plane. Specific features of dissection in the correct and incorrect planes are demonstrated in the accompanying video. The 'triangles' created using appropriate traction can aid in performing a precise dissection in the correct plane. Recognition of features described as 'O's can alert surgeons that they are entering a new fascial plane and can avoid incursion into an incorrect plane. Understanding and recognizing the described features which can be encountered in taTME surgery, a safe and accurate TME dissection can be facilitated.

  15. CrossFit-related cervical internal carotid artery dissection.

    Science.gov (United States)

    Lu, Albert; Shen, Peter; Lee, Paul; Dahlin, Brian; Waldau, Ben; Nidecker, Anna E; Nundkumar, Anoop; Bobinski, Matthew

    2015-08-01

    CrossFit is a high-intensity strength and conditioning program that has gained popularity over the past decade. Potential injuries associated with CrossFit training have been suggested in past reports. We report three cases of cervical carotid dissection that are associated with CrossFit workouts. Patient 1 suffered a distal cervical internal carotid artery (ICA) dissection near the skull base and a small infarct in Wernicke's area. He was placed on anticoagulation and on follow-up has near complete recovery. Patient 2 suffered a proximal cervical ICA dissection that led to arterial occlusion and recurrent middle cerebral artery territory infarcts and significant neurological sequelae. Patient 3 had a skull base ICA dissection that led to a partial Horner's syndrome but no cerebral infarct. While direct causality cannot be proven, intense CrossFit workouts may have led to the ICA dissections in these patients.

  16. Prosection In Place Of Human Dissection – Way Out Of Scarcity Of ...

    African Journals Online (AJOL)

    Prosection In Place Of Human Dissection – Way Out Of Scarcity Of Cadaver ... in the use of conventional human dissection and autopsies for teaching in some parts ... Many academics conventional dissection of the human body as a teaching ...

  17. Outcome from balloon induced coronary artery dissection after intracoronary beta radiation

    NARCIS (Netherlands)

    I.P. Kay (Ian Patrick); S.G. Carlier (Stephan); V.L.M.A. Coen (Veronique); P.J. de Feyter (Pim); M. Sabaté (Manel); G.J.J. van Langenhove (Glenn); M.A. Costa (Marco); A.J. Wardeh (Alexander); A.L. Gijzel (Anthonie); N.V. Deshpande (Niteen Vijay); P.W.J.C. Serruys (Patrick); P.C. Levendag (Peter); W.J. van der Giessen (Wim)

    2000-01-01

    textabstractOBJECTIVE: To evaluate the healing of balloon induced coronary artery dissection in individuals who have received beta radiation treatment and to propose a new intravascular ultrasound (IVUS) dissection score to facilitate the comparison of dissection through time.

  18. Structural Dissection for Controlling Complex Networks

    CERN Document Server

    Wang, Wen-Xu; Zhao, Chen; Liu, Yang-Yu; Lai, Ying-Cheng

    2015-01-01

    Controlling complex networked systems has been a central goal in different fields and understanding controllability of complex networks has been at the forefront of contemporary science. Despite the recent progress in the development of controllability theories for complex networks, we continue to lack efficient tools to fully understand the effect of network topology and interaction strengths among nodes on controllability. Here we establish a framework to discern the significance of links and nodes for controlling general complex networks in a simple way based on local information. A dissection process is offered by the framework to probe and classify nodes and links completely, giving rise to a criterion for strong structural controllability. Analytical results indicate phase transitions associated with link and node categories, and strong structural controllability. Applying the tools to real networks demonstrate that real technological networks are strong structurally controllable, whereas most of real s...

  19. Nanoscale scraping and dissection of collagen fibrils.

    Science.gov (United States)

    Wenger, M P E; Horton, M A; Mesquida, P

    2008-09-24

    The main function of collagen is mechanical, hence there is a fundamental scientific interest in experimentally investigating the mechanical and structural properties of collagen fibrils on the nanometre scale. Here, we present a novel atomic force microscopy (AFM) based scraping technique that can dissect the outer layer of a biological specimen. Applied to individual collagen fibrils, the technique was successfully used to expose the fibril core and reveal the presence of a D-banding-like structure. AFM nanoindentation measurements of fibril shell and core indicated no significant differences in mechanical properties such as stiffness (reduced modulus), hardness, adhesion and adhesion work. This suggests that collagen fibrils are mechanically homogeneous structures. The scraping technique can be applied to other biological specimens, as demonstrated on the example of bacteria.

  20. Influence of a Dissection Video Clip on Anxiety, Affect, and Self-Efficacy in Educational Dissection: A Treatment Study

    Science.gov (United States)

    Randler, Christoph; Demirhan, Eda; Wüst-Ackermann, Peter; Desch, Inga H.

    2016-01-01

    In science education, dissections of animals are an integral part of teaching, but they often evoke negative emotions. We aimed at reducing negative emotions (anxiety, negative affect [NA]) and increasing positive affect (PA) and self-efficacy by an experimental intervention using a predissection video to instruct students about fish dissection.…

  1. A Parallax-based Distance Estimator for Spiral Arm Sources

    CERN Document Server

    Reid, M J; Menten, K M; Brunthaler, A

    2016-01-01

    The spiral arms of the Milky Way are being accurately located for the first time via trigonometric parallaxes of massive star forming regions with the BeSSeL Survey, using the Very Long Baseline Array and the European VLBI Network, and with the Japanese VERA project. Here we describe a computer program that leverages these results to significantly improve the accuracy and reliability of distance estimates to other sources that are known to follow spiral structure. Using a Bayesian approach, sources are assigned to arms based on their (l,b,v) coordinates with respect to arm signatures seen in CO and HI surveys. A source's kinematic distance, displacement from the plane, and proximity to individual parallax sources are also considered in generating a full distance probability density function. Using this program to estimate distances to large numbers of star forming regions, we generate a realistic visualization of the Milky Way's spiral structure as seen from the northern hemisphere.

  2. The scientific objectives of the SPIRAL 2 Project

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, D.; Adoui, L.; Angelis, G. de [GANIL, Grand Accelerateur National d' Ions Lourds, BP 55027, 14076 Caen cedex 5 (France)] (and others)

    2006-06-15

    The construction of SPIRAL 2 at GANIL will open completely new possibilities for parallel beam operation of the whole facility. The whole GANIL/SPIRAL/SPIRAL2 accelerator complex will allow for the simultaneous use of up to 5 different radioactive and stable beams. Several combinations of different beams delivered in parallel for experiments at low (keV/u), medium (few MeV/u) and high (up to 100 MeV/u) energies will be possible. Presently the GANIL/SPIRAL facility delivers about 60 weeks per year of stable and radioactive beams (up to 3 simultaneous beams). Thanks to SPIRAL 2 and the construction of a new beam line connecting the CIME cyclotron and the G1 and G2 experimental rooms the available beam time for experiments may be extended up to about 120 (up to 5 simultaneous beams) weeks per year. The chapters which follow a general introduction deal with the detailed questions to be addressed by experiments with the beams from SPIRAL2. In chapter 2 the many unanswered questions related to the structure of exotic nuclei are posed and the role of SPIRAL2 in answering them outlined. Chapter 3 deals with the dynamics and thermodynamics of asymmetric nuclear systems. Chapter 4 is concerned with questions of nuclear astrophysics which are intimately related to the properties of exotic nuclei. Chapter 5 indicates how the atomic nucleus can act as a laboratory for tests of the Standard model of Particle Physics and Chapter 6 shows how the production of intense fluxes of neutrons at SPIRAL2 make it an excellent tool to address both questions related to damage in materials of importance in nuclear installations and to the s- and r-processes of nucleosynthesis. In chapter 7 we turn to the application, of the radioactive beams from SPIRAL2 and the radionuclides produced by it, to study condensed matter and radiobiology. Finally in the eight and last chapter the reader can find an account of the historical development of the SPIRAL2 facility and this is followed by an outline of

  3. Study and Design of Spiral Bent Waveguide Configuration

    Institute of Scientific and Technical Information of China (English)

    ZENG Wen-hong; LIAO Yun; SHI Shuang-jin; QIU Qi; LI Wei

    2007-01-01

    A new version of the scalar transverse electric(TE) wave equation in the bent waveguide is introduced.Then,TE polarized field in curved single-mode waveguides is analyzed by using the finite-difference beam propagation method(FD-BPM).The bending loss in bent waveguides is gotten for the optical fields obtained from BPM and comparisons are made among losses of the waveguides with various curvature radiuses,refractive index differences and cross sections.Based on the results,the design of spiral bent waveguide configuration is proposed as follows:refractive index difference being of 0.007,both width and thickness of waveguides being of 6 μm,the curvature radius in the spiral centre being of 4 mm,and the bending loss coefficient of the designed spiral bent waveguide being of 0.302 3 dB/cm.

  4. A Twin Spiral Planar Antenna for UWB Medical Radars

    Directory of Open Access Journals (Sweden)

    Giuseppe A. Zito

    2013-01-01

    Full Text Available A planar-spiral antenna to be used in an ultrawideband (UWB radar system for heart activity monitoring is presented. The antenna, named “twin,” is constituted by two spiral dipoles in a compact structure. The reflection coefficient at the feed point of the dipoles is lower than −8 dB over the 3–12 GHz band, while the two-dipoles coupling is about −20 dB. The radiated beam is perpendicular to the plane of the spiral, so the antenna is wearable and it may be an optimal radiator for a medical UWB radar for heart rate detection. The designed antenna has been also used to check some hypotheses about the UWB radar heart activity detection mechanism. The radiation impedance variation, caused by the thorax vibrations associated with heart activity, seems to be the most likely explanation of the UWB radar operation.

  5. Generation of speckle vortices by Archimedes' spiral micro-holes

    Science.gov (United States)

    Sun, Haibin; Liu, Tingting; Chen, Jun; Sun, Ping

    2016-10-01

    Speckle plays an important role in the optical field. Optical vortices which exist in random speckle fields usually contain useful phase information. The distribution of speckle field is determined by these optical vortices. In order to study speckle vortices quantitatively, we established a micro-holes array model based on the law of Archimedes' spiral arrangement. Speckle vortices can be generated by the random diffuse reflection points (spiral micro-holes). In the experiments, the gray image of Archimedes' spiral micro-holes are displayed on the screen of liquid crystal spatial light modulator (LC-SLM), and the output optical field is captured by a CCD camera. The numerical simulations and experimental results show that the model can be used to generate speckle vortices.

  6. Asymmetric propagation of electromagnetic waves through nanoscale spirals

    Science.gov (United States)

    Hu, Jingpei; Lin, Yu; Zhu, Aijiao; Zhao, Xiaonan; Wang, Chinhua

    2016-10-01

    In this paper, we report that normal incidence transmission of different circularly polarized waves through the 2D Archimedes' nanoscale spirals is asymmetric. The structures consist of raised spiral ridge and two layers metal film covered on the substrate and the ridge. The finite difference time domain method was used to design the structure and perform the simulation. The device can distinguish the different circularly polarized wave across the transmission intensity compare with the common Archimedes' nanoscale spirals which just exhibit the bright or dark modes in the light field. We confirmed that the device provide about 10% circular dichroism in 3.85um-6.0um broadband region. The circular dichroism in the wavelength 3.95 um can reach 13%. This ultracompact device could prove useful for remote sensing and advanced telecommunication applications.

  7. The rotation curve of spiral galaxies and its cosmological implications

    CERN Document Server

    Florido, E

    2000-01-01

    We review the topic of rotation curves of spiral galaxies emphasizing the standard interpretation as evidence for the existence of dark matter halos. Galaxies other than spirals and late-type dwarfs may also possess great amounts of dark matter, and therefore ellipticals, dwarf spirals, lenticulars and polar ring galaxies are also considered. Furthermore, other methods for determining galactic dark matter, such as those provided by binaries, satellites or globular clusters, have to be included. Cold dark matter hierarchical models constitute the standard way to explain rotation curves, and thus the problem becomes just one aspect of a more general theory explaining structure and galaxy formation. Alternative theories also are included. In the magnetic model, rotation curves could also be a particular aspect of the whole history of cosmic magnetism during different epochs of the Universe. Modifications of Newtonian Dynamics provide another interesting possibility which is discussed here.

  8. Simulation algorithm for spiral case structure in hydropower station

    Institute of Scientific and Technical Information of China (English)

    Xin-yong XU; Zhen-yue MA; Hong-zhan ZHANG

    2013-01-01

    In this study, the damage-plasticity model for concrete that was verified by the model experiment was used to calculate the damage to a spiral case structure based on the damage mechanics theory. The concrete structure surrounding the spiral case was simulated with a three-dimensional finite element model. Then, the distribution and evolution of the structural damage were studied. Based on investigation of the change of gap openings between the steel liner and concrete structure, the impact of the non-uniform variation of gaps on the load-bearing ratio between the steel liner and concrete structure was analyzed. The comparison of calculated results of the simplified and simulation algorithms shows that the simulation algorithm is a feasible option for the calculation of spiral case structures. In addition, the shell-spring model was introduced for optimization analysis, and the results were reasonable.

  9. The formation of spiral arms and rings in barred galaxies

    CERN Document Server

    Romero-Gomez, M; Masdemont, J J; García-Gomez, C

    2007-01-01

    We propose a new theory to explain the formation of spiral arms and of all types of outer rings in barred galaxies. We have extended and applied the technique used in celestial mechanics to compute transfer orbits. Thus, our theory is based on the chaotic orbital motion driven by the invariant manifolds associated to the periodic orbits around the hyperbolic equilibrium points. In particular, spiral arms and outer rings are related to the presence of heteroclinic or homoclinic orbits. Thus, R1 rings are associated to the presence of heteroclinic orbits, while R1R2 rings are associated to the presence of homoclinic orbits. Spiral arms and R2 rings, however, appear when there exist neither heteroclinic nor homoclinic orbits. We examine the parameter space of three realistic, yet simple, barred galaxy models and discuss the formation of the different morphologies according to the properties of the galaxy model. The different morphologies arise from differences in the dynamical parameters of the galaxy.

  10. Spiral density wave generation by vortices in Keplerian flows

    CERN Document Server

    Bodo, G; Murante, G; Tevzadze, A; Rossi, P; Ferrari, A

    2005-01-01

    We perform a detailed analytical and numerical study of the dynamics of perturbations (vortex/aperiodic mode, Rossby and spiral-density waves) in 2D compressible disks with a Keplerian law of rotation. We draw attention to the process of spiral-density wave generation from vortices, discussing, in particular, the initial, most peculiar stages of wave emission. We show that the linear phenomenon of wave generation by vortices in smooth (without inflection points) shear flows found by using the so-called non-modal approach, is directly applicable to the present case. After an analytical non-modal description of the physics and characteristics of the spiral-density wave generation/propagation in the local shearing-sheet model, we follow the process of wave generation by small amplitude coherent circular vortex structures, by direct global numerical simulation, describing the main features of the generated waves.

  11. Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51

    CERN Document Server

    Egusa, Fumi; Koda, Jin; Baba, Junichi

    2016-01-01

    Theoretical studies on the response of interstellar gas to a gravitational potential disc with a quasi-stationary spiral arm pattern suggest that the gas experiences a sudden compression due to standing shock waves at spiral arms. This mechanism, called a galactic shock wave, predicts that gas spiral arms move from downstream to upstream of stellar arms with increasing radius inside a corotation radius. In order to investigate if this mechanism is at work in the grand-design spiral galaxy M51, we have measured azimuthal offsets between the peaks of stellar mass and gas mass distributions in its two spiral arms. The stellar mass distribution is created by the spatially resolved spectral energy distribution fitting to optical and near infrared images, while the gas mass distribution is obtained by high-resolution CO and HI data. For the inner region (r < 150"), we find that one arm is consistent with the galactic shock while the other is not. For the outer region, results are less certain due to the narrower...

  12. Paediatric tonsillectomy: radiofrequency-based plasma dissection compared to cold dissection with sutures

    Science.gov (United States)

    Di Rienzo Businco, L; Coen Tirelli, G

    2008-01-01

    Summary Aim of this study was to compare post-operative recovery over 14 days in children submitted to tonsillectomy using a bipolar radiofrequency-based plasma device (Coblation®, Evac 70, ArthroCare Corp, Sunnyvale, CA, USA) to cold dissection. Paediatric patients (n = 42) aged 5-16 years old with chronic tonsillitis underwent tonsillectomy using cold dissection with suture ligatures or a plasma device (Evac 70, ArthroCare Corp, Sunnyvale, CA, USA). Pain intensity on the first day, use of analgesics, type of diet, and days of pain, fever, nausea, and absence from school were determined. Groups were compared using time-to-event (Kaplan-Meier) curves and statistically evaluated using the Breslow (generalized Wilcoxon) test. Children undergoing plasma tonsillectomy reported significantly less pain on the first post-operative day (1.2 ± 0.9 vs. 3.5 ± 1.5, p tonsillectomy was adopted for the majority of cases. Benefits of the plasma device include the possibility both to excise tissue and coagulate bleeding vessels using the same device whilst improving quality of post-operative recovery over cold dissection with suture ligatures. PMID:18669070

  13. Tidal Origin of Spiral Arms in Galaxies Orbiting a Cluster

    Science.gov (United States)

    Semczuk, Marcin; Łokas, Ewa L.; del Pino, Andrés

    2017-01-01

    One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the potential of a galaxy cluster. Using N-body simulations we investigate the formation and evolution of spiral arms in a Milky-Way-like galaxy orbiting a Virgo-like cluster. The galaxy is placed on a few orbits of different size but similar eccentricity and its evolution are followed for 10 Gyr. The tidally induced, two-armed, approximately logarithmic spiral structure forms on each of them during the pericenter passages. The spiral arms dissipate and wind up with time, to be triggered again at the next pericenter passage. We confirm this transient and recurrent nature of the arms by analyzing the time evolution of the pitch angle and the arm strength. We find that the strongest arms are formed on the tightest orbit; however, they wind up rather quickly and are disturbed by another pericenter passage. The arms on the most extended orbit, which we analyze in more detail, wind up slowly and survive for the longest time. Measurements of the pattern speed of the arms indicate that they are kinematic density waves. We attempt a comparison with observations by selecting grand-design spiral galaxies in the Virgo cluster. Among those, we find nine examples bearing no sign of recent interactions or the presence of companions. For three of them we present close structural analogues among our simulated spiral galaxies.

  14. IV DSA in the diagnosis and follow-up of dissection of the thoracic aorta

    Energy Technology Data Exchange (ETDEWEB)

    Hendrickx, P.; Luska, G.; Laas, J.; Haverich, A.

    1986-05-01

    Intravenous DSA was performed in 53 patients with suspected dissection of the thoracic aorta and in 13 patients following surgery for aortic dissection. In 36 patients, the suspected diagnosis could be excluded definitely and, in 14 cases out of 17, a dissection was correctly diagnosed. All 11 type B dissections were correctly diagnosed. Of six type A dissections, only three were adequately demonstrated by IV DSA. In type B dissections, IV DSA is reliable, but in type A dissection with massive aortic insufficiency or pericardial tamponade the findings are not reliable. In all 13 patients who had surgery for dissection, IV DSA proved suitable for showing the anastomosis and progress of the disease.

  15. Quantitative imaging of complex samples by spiral phase contrast microscopy.

    Science.gov (United States)

    Bernet, Stefan; Jesacher, Alexander; Fürhapter, Severin; Maurer, Christian; Ritsch-Marte, Monika

    2006-05-01

    Recently a spatial spiral phase filter in a Fourier plane of a microscopic imaging setup has been demonstrated to produce edge enhancement and relief-like shadow formation of amplitude and phase samples. Here we demonstrate that a sequence of at least 3 spatially filtered images, which are recorded with different rotational orientations of the spiral phase plate, can be used to obtain a quantitative reconstruction of both, amplitude and phase information of a complex microscopic sample, i.e. an object consisting of mixed absorptive and refractive components. The method is demonstrated using a calibrated phase sample, and an epithelial cheek cell.

  16. Rotation and mass in the Milky Way and spiral galaxies

    Science.gov (United States)

    Sofue, Yoshiaki

    2017-02-01

    Rotation curves are the basic tool for deriving the distribution of mass in spiral galaxies. In this review, we describe various methods to measure rotation curves in the Milky Way and spiral galaxies. We then describe two major methods to calculate the mass distribution using the rotation curve. By the direct method, the mass is calculated from rotation velocities without employing mass models. By the decomposition method, the rotation curve is deconvolved into multiple mass components by model fitting assuming a black hole, bulge, exponential disk, and dark halo. The decomposition is useful for statistical correlation analyses among the dynamical parameters of the mass components. We also review recent observations and derived results.

  17. Incommensurate Spiral Order from Double-Exchange Interactions

    Science.gov (United States)

    Azhar, Maria; Mostovoy, Maxim

    2017-01-01

    The double-exchange model describing interactions of itinerant electrons with localized spins is usually used to explain ferromagnetism in metals. We show that for a variety of crystal lattices of different dimensionalities and for a wide range of model parameters, the ferromagnetic state is unstable against a noncollinear spiral magnetic order. We revisit the phase diagram of the double-exchange model on a triangular lattice and show in a large part of the diagram the incommensurate spiral state has a lower energy than the previously discussed commensurate states. These results indicate that double-exchange systems are inherently frustrated and can host unconventional spin orders.

  18. Digital spiral-slit for bi-photon imaging

    Science.gov (United States)

    McLaren, Melanie; Forbes, Andrew

    2017-04-01

    Quantum ghost imaging using entangled photon pairs has become a popular field of investigation, highlighting the quantum correlation between the photon pairs. We introduce a technique using spatial light modulators encoded with digital holograms to recover both the amplitude and the phase of the digital object. Down-converted photon pairs are entangled in the orbital angular momentum basis, and are commonly measured using spiral phase holograms. Consequently, by encoding a spiral ring-slit hologram into the idler arm, and varying it radially we can simultaneously recover the phase and amplitude of the object in question. We demonstrate that a good correlation between the encoded field function and the reconstructed images exists.

  19. Status of the SPIRAL I upgrade at GANIL

    Energy Technology Data Exchange (ETDEWEB)

    Jardin, P.; Bajeat, O.; Delahaye, P.; Dubois, M.; Feierstein, C.; Pellemoine, F.; Lecomte, P.; Leherissier, P.; Maunoury, L.; Saint-Laurent, M. G.; Traykov, E. [GANIL, Grand Accelerateur National d' Ions Lourds, CEA-DSM/CNRS-IN2P3, Blvd. H. Becquerel, BP 55027 14076 Caen Cedex 5 (France); Couratin, C. [LPC, Laboratoire de Physique Corpusculaire, CNRS-IN2P3/Universite de Caen Basse-Normandie/ENSICaen, Blvd. Marechal Juin, 14050 Caen Cedex (France)

    2012-02-15

    The upgrade of the ''Systeme de Production d'Ions Radioactifs en Ligne'' phase I (SPIRAL I) installed at the ''Grand Accelerateur National d'Ions Lourds'' (GANIL) situated at Caen, France, is in progress and should be ready by 2014. In parallel, the first part of SPIRAL II facility is currently under construction. The global status of the upgrade is presented: goal, radioactive ion production systems, modification of the production cave and impact of the current safety re-evaluation of GANIL.

  20. Effect of the silicon substrate structure on chip spiral inductor

    Institute of Scientific and Technical Information of China (English)

    Chunlai XUE; Fei YAO; Buwen CHENG; Qiming WANG

    2008-01-01

    In this paper, the effect of the substrate structure on the performance of the spiral inductor is investigated by the 3-D electromagnetic simulator, Ansoft high frequency structure simulator (HFSS). With variations in the substrate structure including substrate conductivity, permittivity and thickness of the dielectric layer, the performance of the inductors has been analyzed in detail. The simulation results and analyses indicate that the performance of the spiral inductor can be mostly improved by lowering the conductivity of the substrate, increasing the thickness of the dielectric layer and using the low K dielectric layer. In the mean time, some guidelines or "design rules" are summarized by the results of this study.

  1. Illuminating the Role of Spiral Waves in Circumstellar Disks

    Science.gov (United States)

    Bae, Jaehan; Hartmann, Lee W.

    2017-01-01

    The transport of angular momentum and mass, and the generation of turbulence, play a crucial role in the evolution of a variety of astrophysical disks. Spiral waves, driven for instance by companion bodies or instabilities, have long been recognized as an important means for the aforementioned two processes. In this dissertation talk, I will discuss an instability of spiral waves that I have recently come across. I will begin by presenting the results from a three-dimensional global hydrodynamic simulation which described the growth and saturation of the instability. The spiral wave instability (SWI) arises as inertial modes, natural oscillations in rotating systems, amplify when they resonantly couple to and extract energy from the background spiral waves. This leads to break down of the spiral waves into turbulence when the velocity perturbations caused by unstable inertial modes reach a similar magnitude to those induced by the spiral waves. As an implication of the instability, I will present numerical results and discuss the consequence of the SWI when it acts on the spiral waves driven by a Jupiter-mass planet in a protoplanetary disk. I find that the planet-driven spiral arms are destabilized via the SWI, generating hydrodynamic turbulence and sustained vertical flows that are associated with long wavelength inertial modes. The associated vertical diffusion rate measured from the simulations is such that solid particles with sizes up to a few centimeters are vertically mixed within the first scale height in a protosolar nebula-like disk. Since circumstellar disks are believed to remain laminar, and thus to induce no or very little particle stirring as suggested by recent magnetocentrifugal wind models, the results imply that the SWI can be the mechanism controlling the degree of vertical settling of solid particles in planet-hosting disks. In particular, if accretion of mm- to cm-sized pebbles dominates the growth of terrestrial bodies, the stirring of solid

  2. Eventful Evolution of Giant Molecular Clouds in Dynamically Evolving Spiral Arms

    CERN Document Server

    Baba, Junichi; Saitoh, Takayuki R

    2016-01-01

    The formation and evolution of giant molecular clouds (GMCs) in spiral galaxies have been investigated in the traditional framework of the combined quasi-stationary density wave and galactic shock model. However, our understanding of the dynamics of spiral arms is changing from the traditional spiral model to a dynamically evolving spiral model. In this study, we investigate the structure and evolution of GMCs in a dynamically evolving spiral arm using a three-dimensional N-body/hydrodynamic simulation of a barred spiral galaxy at parsec-scale resolution. This simulation incorporated self-gravity, molecular hydrogen formation, radiative cooling, heating due to interstellar far-ultraviolet radiation, and stellar feedback by both HII regions and Type-II supernovae. In contrast to a simple expectation based on the traditional spiral model, the GMCs exhibited no systematic evolutionary sequence across the spiral arm. Our simulation showed that the GMCs behaved as highly dynamic objects with eventful lives involvi...

  3. A spiral wave front beacon for underwater navigation: basic concept and modeling.

    Science.gov (United States)

    Hefner, Brian T; Dzikowicz, Benjamin R

    2011-06-01

    A spiral wave front source produces an acoustic field that has a phase that is proportional to the azimuthal angle about the source. The concept of a spiral wave front beacon is developed by combining this source with a reference source that has a phase that is constant with the angle. The phase difference between these sources contains information about the receiver's azimuthal angle relative to the beacon and can be used for underwater navigation. To produce the spiral wave front, two sources are considered: a "physical-spiral" source, which produces the appropriate phase by physically deforming the active element of the source into a spiral, and a "phased-spiral" source, which uses an array of active elements, each driven with the appropriate phase, to produce the spiral wave front. Using finite element techniques, the fields produced by these sources are examined in the context of the spiral wave front beacon, and the advantages of each source are discussed.

  4. Seismic cyclic loading test of SRC columns confined with 5-spirals

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Presented herein is an experimental study on seismic resistance of rectangular steel reinforced concrete (SRC) columns confined with a new type of multi-spiral cage. The multi-spiral cage is a device of five interconnected spirals, named "5-spirals", with a large spiral at the center and four small ones at the corners. The innovation of applying the 5-spirals to SRC column is to take its superiority in concrete confinement and efficiency in automatic production for the precast construction industry. Four full-scale SRC columns were tested under horizontal cyclic loading. All of the tested columns were capable of sustaining a drift angle up to 6% radians. The hysteresis loops observed from the cyclic loading tests indicated that the spirally confined SRC columns demonstrated excellent performances in both strength and ductility. The test results suggested that with significant saving of the confinement steel, the newly innovated 5-spirals can be successfully applied to the precast rectangular SRC columns.

  5. Formation and instability of spiral wave induced by Gaussian coloured noise

    Institute of Scientific and Technical Information of China (English)

    Gan Zheng-Ning; Ma Jun; Zhang Guo-Yong; Chen Yong

    2008-01-01

    In this paper,we studied the effect of Gauesian coloured noise on the formation and instability of spiral waves described by one class of modified FitzHugh-Nagumo equation.It was found that Gaussian coloured noise plays a constructive role in the formation,transition and instability of spiral wave.Too weak or too strong noise may act against the formation of spiral waves.At a certain noise level,spiral wave is maintained in a medium,in which spiral wave cannot be observed in the absence of the noise.It is difficult to make a stable spiral wave into unstable state by Gaussian coloured noise,unless the noise level is very high.The parameter regions of Gaussian coloured noise for spiral forming and spiral instability were given and discussed with numerical simulations.

  6. Spiral wave drift and complex-oscillatory spiral waves caused by heterogeneities in two-dimensional in vitro cardiac tissues

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Sung-Jae; Hong, Jin Hee; Kim, Tae Yun; Bae, Byung Wook; Lee, Kyoung J [CRI Center for Neurodynamics and Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of)], E-mail: kyoung@nld.korea.ac.kr

    2008-01-15

    Understanding spiral reentry wave dynamics in cardiac systems is important since it underlies various cardiac arrhythmia including cardiac fibrillation. Primary cultures of dissociated cardiac cells have been a convenient and useful system for studying cardiac wave dynamics, since one can carry out systematic and quantitative studies with them under well-controlled environments. One key drawback of the dissociated cell culture is that, inevitably, some spatial inhomogeneities in terms of cell types and density, and/or the degree of gap junction connectivity, are introduced to the system during the preparation. These unintentional spatial inhomogeneities can cause some non-trivial wave dynamics, for example, the entrainment dynamics among different spiral waves and the generation of complex-oscillatory spiral waves. The aim of this paper is to quantify these general phenomena in an in vitro cardiac system and provide explanations for them with a simple physiological model having some realistic spatial inhomogeneities incorporated.

  7. Light-Gradient-Induced Spiral Wave Drifts in a Belousov-Zhabotinsky Reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-Jie; WANG Peng-Ye; ZHAO Ying-Ying

    2005-01-01

    @@ The dynamic behaviour of spiral tip in the light-sensitive Belousov-Zhabotinsky reaction under the influence of an externally applied light gradient was experimentally studied. The gradient causes different drifts for different spiral patterns. The centre of the spiral wave moved toward the region of lower light intensity. The direction of an additional perpendicular drift depended on the chirality of the spiral wave. The dependences of the drifting angle and the drifting velocity on light gradient have been measured.

  8. Hydro-dissection - A simple Solution in Difficult Laparoscopic Cholecystectomy.

    Science.gov (United States)

    Lubna, H; Masoom, M R

    2015-07-01

    This Quasi-experimental study was done to assess the effectiveness of hydro-dissection in difficult laparoscopic cholecystectomies in Hamdard University Hospital, Karachi, Pakistan, from April 2012 to March 2014. All consecutive patients who presented with cholelithiasis and planned for laparoscopic cholecystectomy were enrolled in this study. Per-operatively the degree of difficulty of the operation was assessed by Cuschieri's scale after grading; Grade II, III and IV cholecystectomies were included in this study. Hydro dissection with saline jet through 5mm simple irrigation and suction probe was used, Operative findings and the total number of patients, in whom anatomy of calot's triangle was clearly displayed with hydro-dissection, was recorded. A total 55 patients were included in the study after assessing the degree of difficulty per operatively by Cuschieri Scale. Thirty one (31) patients were in Group II, 22 in Group III and 02 were included in group IV of Cuschieri scale in which hydro-dissection was used. This method cleared the obscure anatomy in all patients in Group II but in 3 patients of Group III, dense adhesions required sharp dissection to clear the operative field. Two patients, in whom conversion was required, were grouped in Cuschieri's scale IV. Methods of dissection in difficult cholecystectomies are of paramount importance to avoid iatrogenic injuries. Hydro-dissection using suction irrigation probe is a safe and effective technique to clear the difficult anatomy.

  9. Wideband Cavity Backed Spiral Antenna for Stepped Frequency Ground Penetrating Radar

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne; Lenler-Eriksen, Hans-Rudolph

    2005-01-01

    A 1.7 turn cavity backed coplanar waveguide to coplanar strip-fed logarithmic uniplanar spiral antenna is presented and compared to a 1.5 turn spiral antenna. The 1.7 turn spiral antenna has a wide beamwidth, are circular polarised and has a bandwidth with a return loss better than 6 d...

  10. Controlling Spiral Waves by Modulations Resonant with the Intrinsic System Mode

    Institute of Scientific and Technical Information of China (English)

    XIAO Jing-Hua; HU Gang; HU Bam-Bi

    2004-01-01

    We investigate the spiral wave control in the two-dimensional complex Ginzburg-Landau equation. External drivings which are not resonant with spiral waves but with intrinsic system modes are used to successfully annihilate spiral waves and direct the system to various target states. The novel control mechanism is intuitively explained and the richness and flexibility the control results are emphasized.

  11. Dynamics of the Spiral Tip in a Closed Belousov-Zhabotinsky Reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-Jie; WANG Peng-Ye; ZHAO Ying-Ying

    2005-01-01

    @@ Dynamics of spiral tip rotating in a closed system of the light sensitive Belousov-Zhabotinsky reaction is studied under a homogeneous and steady illumination. The time dependence of the kinematical parameters of meandering spiral is presented and the experimental evidence is obtained for self-synchronization of the spiral tip in a closed B-Z system without external feedback.

  12. Fenestrated internal jugular vein: a rare finding in neck dissection.

    Science.gov (United States)

    Moreno-Sánchez, M; Hernández Vila, C; González-García, R; Monje, F

    2015-09-01

    Fenestration of the internal jugular vein (IJV) is an extremely rare phenomenon. An 85-year-old woman was referred to our department with T2N0M0 squamous cell carcinoma of the right floor of the mouth. The patient underwent local resection, an ipsilateral modified type 3 radical neck dissection, and microsurgical reconstruction. During neck dissection, a fenestration was observed in the middle of the IJV. No structure passed through the fenestration. Such anatomical variations are rare, but clinicians and surgeons should be aware of them in order to avoid damage to the important vascular structures, especially if a neck dissection is performed.

  13. Pulmonary Artery Dissection: A Fatal Complication of Pulmonary Hypertension

    Directory of Open Access Journals (Sweden)

    Chuanchen Zhang

    2016-01-01

    Full Text Available Pulmonary artery dissection is extremely rare but it is a really life-threatening condition when it happens. Most patients die suddenly from major bleeding or tamponade caused by direct rupture into mediastinum or retrograde into the pericardial sac. What we are reporting is a rare case of a 46-year-old female patient whose pulmonary artery dissection involves both the pulmonary valve and right pulmonary artery. The patient had acute chest pain and severe dyspnea, and the diagnosis of pulmonary artery dissection was confirmed by ultrasonography and CT angiography. Moreover, its etiology, clinical manifestations, and management are also discussed in this article.

  14. Spontaneous renal artery dissection complicating with renal infarction.

    Science.gov (United States)

    Tsai, Tsung-Han; Su, Jung-Tsung; Hu, Sung-Yuan; Chao, Chih-Chung; Tsan, Yu-Tse; Lin, Tzu-Chieh

    2010-12-01

    Spontaneous renal artery dissection (SRAD) is a rare entity. We reported a 30-year-old healthy man presenting with sudden onset of left flank pain. Abdominal plain film and sonography were unremarkable. The contrast-enhanced abdominal computed tomographic (CT) scan demonstrated a dissecting intimal flap of the left distal renal artery (RA) complicating infarction. Selective angiography of the renal artery disclosed a long dissection of left distal RA with a patent true lumen and occlusion of left accessory RA. Conservative treatment with control of blood pressure and antiplatelet agent was prescribed. The patient was discharged with an uneventful condition on day 5.

  15. Severe orthostatic hypotension due to unilateral carotid artery dissection

    Directory of Open Access Journals (Sweden)

    Nobuyuki Ishii

    2014-06-01

    Full Text Available A 46-year-old woman was admitted to our hospital with mild right-sided hemiparesis and orthostatic hypotension. Magnetic resonance angiography of the neck showed stenosis of the left distal carotid sinus surrounded by intraluminal hyperintensities on both T1-weighted and T2-weighted images, representing a periluminal hematoma secondary to carotid artery dissection. The dissection hyperextended the carotid artery wall and stimulated baroreceptors in the carotid sinus. The stimulated baroreceptors induced carotid sinus hypersensitivity, which may have been related to her orthostatic hypotension. Post-stroke orthostatic hypotension should prompt consideration of carotid artery dissection.

  16. Spore analysis and tetrad dissection of Schizosaccharomyces pombe

    DEFF Research Database (Denmark)

    Ekwall, Karl; Thon, Genevieve

    2017-01-01

    Here we describe the processing of Schizosaccharomyces pombe spores in batches (random spore analysis) or through tetrad dissections. Spores are usually prepared from matings between haploid strains (producing zygotic asci) or from sporulating diploids (producing azygotic asci). In random spore...... analysis, a snail enzyme preparation is used to digest the walls of asci to release free spores that are diluted and plated to form colonies. In tetrad dissection, a needle attached to a micromanipulator is used to pick asci and separate spores. Tetrad dissection has traditionally been the method of choice...

  17. Endovascular coil oclusion of spontaneous ruptured vertebral artery dissecting aneurysm

    Directory of Open Access Journals (Sweden)

    Chiriac A.

    2017-03-01

    Full Text Available Spontaneous dissecting aneurysm of vertebral artery is known as a rare pathological condition causing a subarachnoid hemorrhage in the posterior circulation. The treatment of ruptured vertebral artery dissecting aneurysms is still an important subject of debates in the literature. We present a particular case of ruptured vertebral artery dissecting aneurysms that was treated by only endovascular Guglielmi detachable coils occlusion. A brief review of technical possibilities of treatment of these types of vascular lesions, with their advantages and disadvantages are discussed.

  18. Pseudo-dissection of ascending aorta in inferior myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Grahame K. Goode

    2011-06-01

    Full Text Available Acute aortic dissection is a cardiac emergency which can present as inferior myocardial infarction. It has high morbidity and mortality requiring prompt diagnosis and treatment. Rapid advances in noninvasive imaging modalities have facilitated the early diagnosis of this condition and in ruling out this potentially catastrophic illness. We report an interesting case of a 57 year- old -man who presented with inferior myocardial infarction requiring thrombolysis and temporary pacing wire for complete heart block. An echocardiogram was highly suspicious of aortic dissection. CT scan confirmed that the malposition of the temporary pacing wire through the aorta mimicked aortic dissection.

  19. Long term complications of the intraprostatic spiral. Case report

    DEFF Research Database (Denmark)

    Krogh, J

    1992-01-01

    A 76-year-old man had an intraprostatic spiral inserted to relieve bladder outlet obstruction that was caused by benign prostatic hypertrophy. After 30 months numerous complications had arisen including severe encrustations, urethral stricture, and sclerosis of the bladder neck. Regular replacement...

  20. Advanced Manufacture of Spiral Bevel and Hypoid Gears

    Directory of Open Access Journals (Sweden)

    Vilmos Simon

    2016-11-01

    Full Text Available In this study, an advanced method for the manufacture of spiral bevel and hypoid gears on CNC hypoid generators is proposed. The optmal head-cutter geometry and machine tool settings are determined to introduce the optimal tooth surface modifications into the teeth of spiral bevel and hypoid gears. The aim of these tooth surface modifications is to simultaneously reduce the tooth contact pressure and the transmission errors, to maximize the EHD load carrying capacity of the oil film, and to minimize power losses in the oil film. The proposed advanced method for the manufacture of spiral bevel and hypoid gears is based on machine tool setting variation on the cradle-type generator conducted by optimal polynomial functions and on the use of a CNC hypoid generator. An algorithm is developed for the execution of motions on the CNC hypoid generator using the optimal relations on the cradle-type machine. Effectiveness of the method was demonstrated by using spiral bevel and hypoid gear examples. Significant improvements in the operating characteristics of the gear pairs are achieved.

  1. Gas mass fractions and the evolution of spiral galaxies

    NARCIS (Netherlands)

    McGaugh, SS; DeBlok, WJG

    1997-01-01

    We show that the gas mass fraction of spiral galaxies is strongly correlated with luminosity and surface brightness. It is not correlated with linear size. Gas fraction varies with luminosity and surface brightness at the same rate, indicating evolution at fixed size. Dim galaxies are clearly less e

  2. Enhanced Abundances in Spiral Galaxies of the Pegasus I Cluster

    CERN Document Server

    Robertson, Paul; Blanc, Guillermo A

    2011-01-01

    We study the influence of cluster environment on the chemical evolution of spiral galaxies in the Pegasus I cluster. We determine the gas-phase heavy element abundances of six galaxies in Pegasus derived from H II region spectra obtained from integral-field spectroscopy. These abundances are analyzed in the context of Virgo, whose spirals are known to show increasing interstellar metallicity as a function of H I deficiency. The galaxies in the Pegasus cluster, despite its lower density and velocity dispersion, also display gas loss due to ISM-ICM interaction, albeit to a lesser degree. Based on the abundances of 3 H I deficient spirals and 2 H I normal spirals, we observe a heavy element abundance offset of +0.13\\pm0.07 dex for the H I deficient galaxies. This abundance differential is consistent with the differential observed in Virgo for galaxies with a similar H I deficiency, and we observe a correlation between log(O/H) and the H I deficiency parameter DEF for the two clusters analyzed together. Our resul...

  3. A Parallax-based Distance Estimator for Spiral Arm Sources

    Science.gov (United States)

    Reid, M. J.; Dame, T. M.; Menten, K. M.; Brunthaler, A.

    2016-06-01

    The spiral arms of the Milky Way are being accurately located for the first time via trigonometric parallaxes of massive star-forming regions with the Bar and Spiral Structure Legacy Survey, using the Very Long Baseline Array and the European VLBI Network, and with the Japanese VLBI Exploration of Radio Astrometry project. Here we describe a computer program that leverages these results to significantly improve the accuracy and reliability of distance estimates to other sources that are known to follow spiral structure. Using a Bayesian approach, sources are assigned to arms based on their (l, b, v) coordinates with respect to arm signatures seen in CO and H i surveys. A source's kinematic distance, displacement from the plane, and proximity to individual parallax sources are also considered in generating a full distance probability density function. Using this program to estimate distances to large numbers of star-forming regions, we generate a realistic visualization of the Milky Way's spiral structure as seen from the northern hemisphere.

  4. The local spiral structure of the Milky Way

    CERN Document Server

    Xu, Ye; Dame, Thomas; Menten, Karl; Sakai, Nobuyuki; Li, Jingjing; Brunthaler, Andreas; Moscadelli, Luca; Zhang, Bo; Zheng, Xingwu

    2016-01-01

    The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star formation near the Local spiral arm of the Milky Way. Combined with previous measurements, these observations reveal that the Local Arm is larger than previously thought, and both its pitch angle and star formation rate are comparable to those of the Galaxy's major spiral arms, such as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the Local Arm extend for a great distance along our line of sight and roughly along the solar orbit. Because of this orientation, these sources cluster both on the sky and in velocity to form the complex and long enigmatic Cygnus X region. We also identify a spur that branche...

  5. The observed spiral structure of the Milky Way

    CERN Document Server

    Hou, L G

    2014-01-01

    The spiral structure of the Milky Way is not yet well determined. The keys to understanding this structure are to increase the number of reliable spiral tracers and to determine their distances as accurately as possible. HII regions, giant molecular clouds (GMCs), and 6.7-GHz methanol masers are closely related to high mass star formation, and hence they are excellent spiral tracers. We update the catalogs of Galactic HII regions, GMCs, and 6.7-GHz methanol masers, and then outline the spiral structure of the Milky Way. We collected data for more than 2500 known HII regions, 1300 GMCs, and 900 6.7-GHz methanol masers. If the photometric or trigonometric distance was not yet available, we determined the kinematic distance using a Galaxy rotation curve with the current IAU standard, $R_0$ = 8.5 kpc and $\\Theta_0$ = 220 km s$^{-1}$, and the most recent updated values of $R_0$ = 8.3 kpc and $\\Theta_0$ = 239 km s$^{-1}$, after we modified the velocities of tracers with the adopted solar motions. With the weight fa...

  6. Tidal origin of spiral arms in galaxies orbiting a cluster

    CERN Document Server

    Semczuk, Marcin; del Pino, Andres

    2016-01-01

    One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the potential of a galaxy cluster. Using $N$-body simulations we investigate the formation and evolution of spiral arms in a Milky Way-like galaxy orbiting a Virgo-like cluster. The galaxy is placed on a few orbits of different size but similar eccentricity and its evolution is followed for 10 Gyr. The tidally induced, two-armed, approximately logarithmic spiral structure forms on each of them during the pericenter passages. The spiral arms dissipate and wind up with time, to be triggered again at the next pericenter passage. We confirm this transient and recurrent nature of the arms by analyzing the time evolution of the pitch angle and the arm strength. We find that the strongest arms are formed on the tightest orbit, however they wind up rather quickly and are disturbed by another p...

  7. Spiral intensity patterns in the internally pumped optical parametric oscillator

    DEFF Research Database (Denmark)

    Lodahl, Peter; Bache, Morten; Saffman, Mark

    2001-01-01

    We describe a nonlinear optical system that supports spiral pattern solutions in the field intensity. This new spatial structure is found to bifurcate above a secondary instability in the internally pumped optical parametric oscillator. The analytical predictions of threshold and spatial scale...

  8. Scalable Automated Detection of Spiral Galaxy Arm Segments

    CERN Document Server

    Davis, Darren R

    2014-01-01

    Given an approximately centered image of a spiral galaxy, we describe an entirely automated method that finds, centers, and sizes the galaxy and then automatically extracts structural information about the spiral arms. For each arm segment found, we list the pixels in that segment and perform a least-squares fit of a logarithmic spiral arc to the pixels in the segment. The algorithm takes about 1 minute per galaxy, and can easily be scaled using parallelism. We have run it on all ~644,000 Sloan objects classified as "galaxy" and large enough to observe some structure. Our algorithm is stable in the sense that the statistics across a large sample of galaxies vary smoothly based on algorithmic parameters, although results for individual galaxies can sometimes vary in a non-smooth but easily understood manner. We find a very good correlation between our quantitative description of spiral structure and the qualitative description provided by humans via Galaxy Zoo. In addition, we find that pitch angle often varie...

  9. Vertically Conductive MoS2 Spiral Pyramid.

    Science.gov (United States)

    Ly, Thuc Hue; Zhao, Jiong; Kim, Hyun; Han, Gang Hee; Nam, Honggi; Lee, Young Hee

    2016-09-01

    MoS2 spirals grown by the chemical vapor deposition method, driven by a threading dislocation, has a peculiar rhombohedral-like structure. This threading dislocation can carry helical current in the vertical direction and greatly enhances the vertical conductance in the MoS2 multilayer samples.

  10. Outer Spiral Disks as Clues to Galaxy Formation and Evolution

    CERN Document Server

    Vlajić, Marija

    2010-01-01

    Recent studies of outer spiral disks have given rise to an abundance of new results. We discuss the observational and theoretical advances that have spurred the interest in disk outskirts, as well as where we currently stand in terms of our understanding of outer disk structure, ages and metallicities.

  11. Molecular Distribution in the Spiral Arm of M51

    CERN Document Server

    Watanabe, Yoshimasa; Sorai, Kazuo; Ueda, Junko; Yamamoto, Satoshi

    2016-01-01

    Molecular line images of 13CO, C18O, CN, CS, CH3OH, and HNCO are obtained toward the spiral arm of M51 at a 7" times 6" resolution with the Combined Array for Research in Millimeter-wave Astronomy (CARMA). Distributions of the molecules averaged over a 300 pc scale are found to be almost similar to one another and to essentially trace the spiral arm. However, the principal component analysis shows a slight difference of distributions among molecular species particularly for CH3OH and HNCO. These two species do not correlate well with star-formation rate, implying that they are not enhanced by local star-formation activities but by galactic-scale phenomena such as spiral shocks. Furthermore, the distribution of HNCO and CH3OH are found to be slightly different, whose origin deserves further investigation. The present results provide us with an important clue to understanding the 300 pc scale chemical composition in the spiral arm and its relation to galactic-scale dynamics.

  12. Spiral galaxy distance indicators based on near-infrared photometry

    NARCIS (Netherlands)

    Grijs, R. de; Peletier, R. F.

    1999-01-01

    We compare two methods of distance determination to spiral galaxies using optical/near-infrared (NIR) observations, the (I-K) versus M-K colour-absolute magnitude (CM) relation and the I- and K-band Tully-Fisher relation (TFR). Dust-free colours and NIR absolute magnitudes greatly enhance the

  13. Fingerprints of nucleosynthesis in the local spiral arm

    Science.gov (United States)

    Knoedlseder, J.; Bennett, K.; Bloemen, H.; Diehl, R.; Hermsen, W.; Oberlack, U.; Ryan, J.; Schoenfelder, V.; vonBallmoos, P.

    1997-01-01

    The local spiral arm with its inherent massive star population is a natural site of recent nucleosynthesis activity. The features found in 1.8 MeV observation of candidate Al-26 sources situated in this structure are discussed. The emphasis is on Loop 1, a nearby superbubble which is possibly the site of a recent supernova explosion.

  14. THE SURFACE BRIGHTNESS OF OUR GALAXY AND OTHER SPIRALS

    NARCIS (Netherlands)

    VANDERKRUIT, PC

    1990-01-01

    In this review I discuss some aspects of the luminosity distributions in our Galaxy and external spiral galaxies. The major conclusions are the following: (1) the radial scale length of the luminosity distribution in the disk of our Galaxy is 5.0 +/- 0.5 kpc, (2) on this basis the Hubble constant ne

  15. Elastic Sturmian spirals in the Lorentz-Minkowski plane

    Directory of Open Access Journals (Sweden)

    Uçum Ali

    2016-01-01

    Full Text Available In this paper we consider some elastic spacelike and timelike curves in the Lorentz-Minkowski plane and obtain the respective vectorial equations of their position vectors in explicit analytical form. We study in more details the generalized Sturmian spirals in the Lorentz-Minkowski plane which simultaneously are elastics in this space.

  16. Quintessence-like Dark Matter in Spiral Galaxies

    CERN Document Server

    Matos, T; Núñez, D; Ramírez, E

    2000-01-01

    Through the geodesic analysis of a static and axially symmetric space time,we present conditions over the state equation of an isotropic perfect fluid$p=\\omega d$, when it is considered as dark matter in spiral galaxies. The mainconclusion is that it can be an exotic fluid ($-1<\\omega <-1/3$) as it is foundfor Quintessence at cosmological scale.

  17. EM-wave absorption properties of hollow spiral iron particles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenqiang, E-mail: zwqcau@gmail.com [College of Engineering, China Agricultural University, Beijing 100083 (China); Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

    2015-12-15

    Hollow iron spiral particles were fabricated successfully by thermal decomposition method, and they were heat-treated at different temperatures in N{sub 2} atmosphere. The electromagnetic wave absorption properties of hollow iron spiral particles were investigated ranging between 1 GHz and 18 GHz. The results indicated that the phase structures of the particles changed from amorphous to nanocrystal with the treating temperature rising, also causing the significant change in electromagnetic parameters and the reflection loss. The reflection loss could reach −33 dB at 16.2 GHz, indicating that the hollow iron spiral particles had the potential to be used in prepare the a high property EM-wave absorber. - Highlights: • Hollow iron spiral particles were fabricated by thermal decomposition method. • The particles changed from amorphous to nanocrystals with heat-treatment. • Particles’ EM-parameters have a great change after high temperature heat-treatment. • RL results show the particles have potential to be high property EM-wave absorber.

  18. Tuning magnetic spirals beyond room temperature with chemical disorder

    Science.gov (United States)

    Morin, Mickaël; Canévet, Emmanuel; Raynaud, Adrien; Bartkowiak, Marek; Sheptyakov, Denis; Ban, Voraksmy; Kenzelmann, Michel; Pomjakushina, Ekaterina; Conder, Kazimierz; Medarde, Marisa

    2016-12-01

    In the past years, magnetism-driven ferroelectricity and gigantic magnetoelectric effects have been reported for a number of frustrated magnets featuring ordered spiral magnetic phases. Such materials are of high-current interest due to their potential for spintronics and low-power magnetoelectric devices. However, their low-magnetic ordering temperatures (typically <100 K) greatly restrict their fields of application. Here we demonstrate that the onset temperature of the spiral phase in the perovskite YBaCuFeO5 can be increased by more than 150 K through a controlled manipulation of the Fe/Cu chemical disorder. Moreover, we show that this novel mechanism can stabilize the magnetic spiral state of YBaCuFeO5 above the symbolic value of 25 °C at zero magnetic field. Our findings demonstrate that the properties of magnetic spirals, including its wavelength and stability range, can be engineered through the control of chemical disorder, offering a great potential for the design of materials with magnetoelectric properties beyond room temperature.

  19. Ultra wideband coplanar waveguide fed spiral antenna for humanitarian demining

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne; Appel-Hansen, Jørgen

    2000-01-01

    to 1 bandwidth with a return loss better than 10 dB from 0.4 to 3.8 GHz is presented. A wideband balun covering the frequency range of the antenna was developed. The constructed spiral antenna is very useful in a stepped frequency ground penetrating radar for humanitarian demining due to the very...

  20. Spirals, chaos, and new mechanisms of wave propagation.

    Science.gov (United States)

    Chen, P S; Garfinkel, A; Weiss, J N; Karagueuzian, H S

    1997-02-01

    The chaos theory is based on the idea that phenomena that appear disordered and random may actually be produced by relatively simple deterministic mechanisms. The disordered (aperiodic) activation that characterizes a chaotic motion is reached through one of a few well-defined paths that are characteristic of nonlinear dynamical systems. Our group has been studying VF using computerized mapping techniques. We found that in electrically induced VF, reentrant wavefronts (spiral waves) are present both in the initial tachysystolic stage (resembling VT) and the later tremulous incoordination stage (true VF). The electrophysiological characteristics associated with the transition from VT to VF is compatible with the quasiperiodic route to chaos as described in the Ruelle-Takens theorem. We propose that specific restitution of action potential duration (APD) and conduction velocity properties can cause a spiral wave (the primary oscillator) to develop additional oscillatory modes that lead to spiral meander and breakup. When spiral waves begin to meander and are modulated by other oscillatory processes, the periodic activity is replaced by unstable quasiperiodic oscillation, which then undergoes transition to chaos, signaling the onset of VF. We conclude that VF is a form of deterministic chaos. The development of VF is compatible with quasiperiodic transition to chaos. These results indicate that both the prediction and the control of fibrillation are possible based on the chaos theory and with the advent of chaos control algorithms.

  1. Laboratory-Scale Simulation of Spiral Plumes in the Mantle

    CERN Document Server

    Sharifulin, A N

    2012-01-01

    On the basis of laboratory simulation a mechanism is established for the formation of the upper mantle convection spiral plumes from a hot point in the presence of a roll-type large-scale convective flow. The observed plume has horizontal sections near the upper limit, which may lead to the formation of chains of volcanic islands.

  2. Optogenetic dissection of medial prefrontal cortex circuitry

    Directory of Open Access Journals (Sweden)

    Danai eRiga

    2014-12-01

    Full Text Available The medial prefrontal cortex (mPFC is critically involved in numerous cognitive functions, including attention, inhibitory control, habit formation, working memory and long-term memory. Moreover, through its dense interconnectivity with subcortical regions (e.g. thalamus, striatum, amygdala and hippocampus, the mPFC is thought to exert top-down executive control over the processing of aversive and appetitive stimuli. Because the mPFC has been implicated in the processing of a wide range of cognitive and emotional stimuli, it is thought to function as a central hub in the brain circuitry mediating symptoms of psychiatric disorders. New optogenetics technology enables anatomical and functional dissection of mPFC circuitry with unprecedented spatial and temporal resolution. This provides important novel insights in the contribution of specific neuronal subpopulations and their connectivity to mPFC function in health and disease states. In this review, we present the current knowledge obtained with optogenetic methods concerning mPFC function and dysfunction and integrate this with findings from traditional intervention approaches used to investigate the mPFC circuitry in animal models of cognitive processing and psychiatric disorders.

  3. Optogenetic dissection of medial prefrontal cortex circuitry.

    Science.gov (United States)

    Riga, Danai; Matos, Mariana R; Glas, Annet; Smit, August B; Spijker, Sabine; Van den Oever, Michel C

    2014-01-01

    The medial prefrontal cortex (mPFC) is critically involved in numerous cognitive functions, including attention, inhibitory control, habit formation, working memory and long-term memory. Moreover, through its dense interconnectivity with subcortical regions (e.g., thalamus, striatum, amygdala and hippocampus), the mPFC is thought to exert top-down executive control over the processing of aversive and appetitive stimuli. Because the mPFC has been implicated in the processing of a wide range of cognitive and emotional stimuli, it is thought to function as a central hub in the brain circuitry mediating symptoms of psychiatric disorders. New optogenetics technology enables anatomical and functional dissection of mPFC circuitry with unprecedented spatial and temporal resolution. This provides important novel insights in the contribution of specific neuronal subpopulations and their connectivity to mPFC function in health and disease states. In this review, we present the current knowledge obtained with optogenetic methods concerning mPFC function and dysfunction and integrate this with findings from traditional intervention approaches used to investigate the mPFC circuitry in animal models of cognitive processing and psychiatric disorders.

  4. Model for Simulating a Spiral Software-Development Process

    Science.gov (United States)

    Mizell, Carolyn; Curley, Charles; Nayak, Umanath

    2010-01-01

    A discrete-event simulation model, and a computer program that implements the model, have been developed as means of analyzing a spiral software-development process. This model can be tailored to specific development environments for use by software project managers in making quantitative cases for deciding among different software-development processes, courses of action, and cost estimates. A spiral process can be contrasted with a waterfall process, which is a traditional process that consists of a sequence of activities that include analysis of requirements, design, coding, testing, and support. A spiral process is an iterative process that can be regarded as a repeating modified waterfall process. Each iteration includes assessment of risk, analysis of requirements, design, coding, testing, delivery, and evaluation. A key difference between a spiral and a waterfall process is that a spiral process can accommodate changes in requirements at each iteration, whereas in a waterfall process, requirements are considered to be fixed from the beginning and, therefore, a waterfall process is not flexible enough for some projects, especially those in which requirements are not known at the beginning or may change during development. For a given project, a spiral process may cost more and take more time than does a waterfall process, but may better satisfy a customer's expectations and needs. Models for simulating various waterfall processes have been developed previously, but until now, there have been no models for simulating spiral processes. The present spiral-process-simulating model and the software that implements it were developed by extending a discrete-event simulation process model of the IEEE 12207 Software Development Process, which was built using commercially available software known as the Process Analysis Tradeoff Tool (PATT). Typical inputs to PATT models include industry-average values of product size (expressed as number of lines of code

  5. SMAD2 Mutations Are Associated with Arterial Aneurysms and Dissections.

    Science.gov (United States)

    Micha, Dimitra; Guo, Dong-Chuan; Hilhorst-Hofstee, Yvonne; van Kooten, Fop; Atmaja, Dian; Overwater, Eline; Cayami, Ferdy K; Regalado, Ellen S; van Uffelen, René; Venselaar, Hanka; Faradz, Sultana M H; Vriend, Gerrit; Weiss, Marjan M; Sistermans, Erik A; Maugeri, Alessandra; Milewicz, Dianna M; Pals, Gerard; van Dijk, Fleur S

    2015-12-01

    We report three families with arterial aneurysms and dissections in which variants predicted to be pathogenic were identified in SMAD2. Moreover, one variant occurred de novo in a proband with unaffected parents. SMAD2 is a strong candidate gene for arterial aneurysms and dissections given its role in the TGF-β signaling pathway. Furthermore, although SMAD2 and SMAD3 probably have functionally distinct roles in cell signaling, they are structurally very similar. Our findings indicate that SMAD2 mutations are associated with arterial aneurysms and dissections and are in accordance with the observation that patients with pathogenic variants in genes encoding proteins involved in the TGF-β signaling pathway exhibit arterial aneurysms and dissections as key features.

  6. [Thoracic aortic dissection revealed by systemic cholesterol embolism].

    Science.gov (United States)

    Braem, L; Paule, P; Héno, P; Morand, J J; Mafart, B; La Folie, T; Varlet, P; Mioulet, D; Fourcade, L

    2006-10-01

    Systemic cholesterol embolism is a rare complication of atherosclerosis, and has various presentations. Arterial catheterisms are a common cause. However, the association with an aortic dissection has been exceptionally reported. We report the observation of a 70 year-old man, with coronary artery disease, hypertension, diabetes and dyslipidemia. Six months before hospitalization, a coronary angioplasty was performed due to recurrent angina. The association of purpuric lesions on the feet, with acute renal failure confirmed cholesterol embolism syndrome. Transoesophageal echocardiography showed a dissection of the descending thoracic aorta associated with complex atheroma. The evolution was marked by the pulpar necrosis of a toe and by a worsening of the renal failure, requiring definitive hemodialysis. Further echographic control highlighted the rupture of the intimal veil of the dissection. Cholesterol embolism syndrome may reveal an aortic dissection in patients without thoracic symptoms. In such cases, transoesophageal echocardiography is a useful and non-invasive examination.

  7. An interesting case report of vertebral artery dissection following polytrauma

    Directory of Open Access Journals (Sweden)

    Vikas Acharya

    2016-01-01

    Conclusion: Our report displays select images related to this case report and emphasizes the consideration of routine imaging in head and neck traumatic injuries to diagnose internal carotid and/or vertebral artery dissections much earlier.

  8. Circumareolar Incision‑subdermal Tunneling Dissection for Excision ...

    African Journals Online (AJOL)

    2017 Nigerian Journal of Surgery | Published by Wolters Kluwer - Medknow. Excision of ... superficial fascia with circumareolar incision, subdermal cone‑wise dissection was made to ..... Technical advances in skin sparing mastectomy. Int.

  9. Notch signaling in descending thoracic aortic aneurysm and dissection

    NARCIS (Netherlands)

    Zou, S.; Ren, P.; Nguyen, M.; Coselli, J.S.; Shen, Y.H.; Lemaire, S.A.

    2012-01-01

    BACKGROUND: Descending thoracic aortic aneurysm and dissection (DTAAD) is characterized by progressive medial degeneration, which may result from excessive tissue destruction and insufficient repair. Resistance to tissue destruction and aortic self-repair are critical in preventing medial degenerati

  10. Endovascular treatment of acute type B dissection complicating aortic coarctation.

    Science.gov (United States)

    Kassaian, Seyed Ebrahim; Abbasi, Kyomars; Mousavi, Mehdi; Sahebjam, Mohammad

    2013-01-01

    Surgical treatment poses a high risk to patients with concomitant aortic coarctation and dissection, and an interventional approach could be an alternative. We describe the case of a 52-year-old man with a long history of untreated hypertension and aortic coarctation who emergently presented at our institution with an acute Stanford type B dissection. The patient's elevated serum creatinine level, perfusion deficit in the right lower limb, and hypertension did not respond to medical therapy, and he did not consent to surgery. By endovascular means, we used a self-expandable stent-graft to cover the entry point of the dissection; then, we deployed a balloon-expandable bare-metal stent to correct residual stenosis. To our knowledge, this is the first report of the endovascular treatment of aortic coarctation complicated by type B dissection.

  11. Incidental spontaneous coronary dissection: An interventionist′s dilemma

    Directory of Open Access Journals (Sweden)

    Akshyaya Pradhan

    2015-01-01

    Full Text Available Spontaneous coronary artery dissection (SCAD is an uncommon entity, frequently presenting as ST-elevation myocardial infarction (MI or sudden cardiac death. It is usually reported in association with pregnancy and has a high mortality. We present here a case of asymptomatic dissection of the right coronary artery, incidentally detected, in a young normotensive male when coronary angiography was done following acute anterior wall MI. This patient had none of the risk factors to which SCAD is generally ascribed. While management of the infarct-related artery was clear-cut, whether or not to intervene for this nonocclusive dissection was a difficult decision. A conservative approach was finally adopted for the spontaneous dissection and the patient is faring well till date.

  12. Isolated vagus nerve paralysis associated with internal carotid artery dissection.

    Science.gov (United States)

    Nakagawa, Hideki; Kusuyama, Toshiyuki; Ogawa, Kaoru

    2014-02-01

    Dysphagia and hoarseness caused by laryngopharyngeal paralysis associated with internal carotid artery (ICA) dissection is rare. We reported a case which recovered spontaneously. A 57-year old man visited our hospital complaining of dysphagia and hoarseness lasting for two weeks. Paralysis of right vocal fold and rotational movement of the posterior pharyngeal wall toward the left side during swallowing were observed. Magnetic resonance imaging was performed under diagnosis of isolated right vagus nerve paralysis, and dissection of the right ICA was revealed. He was treated conservatively, and both of laryngopharyngeal movement and the ICA dissection were improved completely. There is a possibility that laryngeal paralysis caused by ICA dissection has been misdiagnosed as an idiopathic paralysis.

  13. Breathing spiral waves in the chlorine dioxide-iodine-malonic acid reaction-diffusion system

    Science.gov (United States)

    Berenstein, Igal; Muñuzuri, Alberto P.; Yang, Lingfa; Dolnik, Milos; Zhabotinsky, Anatol M.; Epstein, Irving R.

    2008-08-01

    Breathing spiral waves are observed in the oscillatory chlorine dioxide-iodine-malonic acid reaction-diffusion system. The breathing develops within established patterns of multiple spiral waves after the concentration of polyvinyl alcohol in the feeding chamber of a continuously fed, unstirred reactor is increased. The breathing period is determined by the period of bulk oscillations in the feeding chamber. Similar behavior is obtained in the Lengyel-Epstein model of this system, where small amplitude parametric forcing of spiral waves near the spiral wave frequency leads to the formation of breathing spiral waves in which the period of breathing is equal to the period of forcing.

  14. Planar Task Space Control of a Biarticular Manipulator Driven by Spiral Motors

    Directory of Open Access Journals (Sweden)

    Ahmad Zaki bin Hj Shukor

    2012-10-01

    Full Text Available This paper elaborates upon a musculoskeletal‐inspired robot manipulator using a prototype of the spiral motor developed in our laboratory. The spiral motors represent the antagonistic muscles due to the high forward/backward drivability without any gears or mechanisms. Modelling of the biarticular structure with spiral motor dynamics was presented and simulations were carried out to compare two control methods, Inverse Kinematics (IK and direct‐Cartesian control, between monoarticular only structures and biarticular structures using the spiral motor. The results show the feasibility of the control, especially in maintaining air gaps within the spiral motor.

  15. Anatomy of the bronchial arteries: imaging via spiral CT. Anatomie der Bronchialarterien - Darstellung mit der Spiral-CT

    Energy Technology Data Exchange (ETDEWEB)

    Schwickert, H.C. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Kauczor, H.U. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Schweden, F. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Schild, H.H. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie)

    1994-06-01

    The purpose of our study was to evaluate the capability of spiral CT in detecting bronchial arteries and in classifying their anatomic variations. Patients and Methods: In 43 patients with different diseases routine spiral CTs of the chest were performed and evaluated retrospectively. Spiral CT was started with a delay of 30 seconds after contrast material application. Results: In 43 patients a total of 67 bronchial arteries were detected: 31 right, 35 left and one common trunk. 26 right bronchial arteries originated medially, 5 anteriorly from the descending aorta, 7 of them together with an intercostal artery. 25 right bronchial arteries passed dorsally, 6 ventrally to the oesophagus. On the left, all 35 bronchial arteries originated from the anterior aorta: 12 led ventrally through the aorticopulmonary window to the ventral wall of the main bronchus, 14 were directed caudally to the cranial and 9 laterally to the posterior aspect of the main bronchus. The discernible length varied between 15 and 90 mm on the right, and between 10 and 37 mm on the left side. Only in two cases did the proximal diameter measure more than 2 mm. Conclusion: Spiral CT offers the possibility to classify the anatomic course and pathologic changes of the bronchial arteries. (orig.)

  16. Dissection of a non-bifurcating cervical carotid artery.

    Science.gov (United States)

    Nas, Omer Fatih; Karakullukcuoglu, Zeynel; Hakyemez, Bahattin; Erdogan, Cuneyt

    2016-06-01

    A non-bifurcating cervical carotid artery is a rare anomaly in the population. Radiologic diagnosis of pathologies seen together with this anomaly can be challenging. Despite not being diagnostic all the time, digital subtraction angiography is accepted as the gold standard method for the diagnosis of dissection. We present a case of a non-bifurcating cervical carotid artery and concomitant dissection, which presented to the hospital with trauma and ischemic findings.

  17. Cerebral Ischemia Due to Traumatic Carotid Artery Dissection: Case Report

    Directory of Open Access Journals (Sweden)

    Deniz Kamacı Şener

    2012-12-01

    Full Text Available Blunt injury to the neck region may lead to carotid artery dissection and cerebral ischemia. Blunt injury to carotid artery is not frequent but determination of the presence of trauma in the history of stroke patients will provide early diagnosis and treatment of them. In this article, a case with cerebral ischemia resulting from traumatic carotid artery dissection is presented and clinical findings, diagnostic procedures and choice of treatment are discussed in the light of the literature.

  18. Descending thoracic aorta dissection associated with esophageal carcinoma

    Directory of Open Access Journals (Sweden)

    Kaushik Saha

    2013-01-01

    Full Text Available The association of aortic dissection with a malignancy is a rare finding and previous reports are usually those of primary aortic sarcomas. A 45-year-old male presented to us with chest pain and dysphagia for 1 month with a background history of obstructive airway disease and uncontrolled hypertension. In this report we present a case of typical descending aorta dissection with associated esophageal carcinoma.

  19. Spontaneous Coronary Artery Dissection following Topical Hormone Replacement Therapy

    OpenAIRE

    2012-01-01

    Spontaneous coronary artery dissection is a rare condition, usually presenting as an acute coronary syndrome, and is often seen in states associated with high systemic estrogen levels such as pregnancy or oral contraceptive use. While topical hormonal replacement therapy may result in increased estrogen levels similar to those documented with oral contraceptive use, there are no reported cases of spontaneous coronary dissection with topical hormonal replacement therapy. We describe a 53-year...

  20. A unique case of isolated, spontaneous, symptomatic celiac trunk dissection

    Directory of Open Access Journals (Sweden)

    Craig Ferguson

    2015-01-01

    Full Text Available Cases of isolated spontaneous celiac trunk dissections have been appearing in the literature more recently with the increased availability of high-resolution computerized tomography angiograms. We report a unique case of this entity. A 48-year-old woman presented with acute abdominal pain that radiated to the back and worsened with breathing. This was diagnosed as a celiac trunk dissection by computerized tomography angiogram. She was treated conservatively with antihypertensive medications, anticoagulants, and opioid medication for pain control.