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Sample records for maron tiina agan

  1. The Agan epithermal gold-silver deposit and prospects for the discovery of high-sulfidation mineralization in northeast Russia

    NASA Astrophysics Data System (ADS)

    Volkov, A. V.; Savva, N. E.; Sidorov, A. A.; Kolova, E. E.; Chizhova, I. A.; Alekseev, V. Yu.

    2015-01-01

    The Arman volcanotectonic depression (VTD) containing the Agan deposit is distinguished as the most promising area for the discovery of high-sulfidation (HS) epithermal Au deposit during prospecting in the Central Okhotsk ore district of the Okhotsk-Chukotka volcanogenic belt (OChVB). Studies reveal that the volcanic rocks of the Agan deposit strongly differ from those of the reference HS-type epithermal deposits. It was found that quartz-alunite metasomatites in the ore field are characterized by low Au content and Sn content two orders of magnitude higher than those of Cu and Mo. The pair-correlation coefficients are K cor (Au-Sn) = 0.73 and K cor(Au-Cu) = 0.22. The ore bodies of the Agan deposit do not contain enargite and luzonite—the main indicator minerals for Au productive HS-type mineralization; porous ("vuggy") quartz is weakly manifested. In terms of the mineral complex, the epithermal mineralization revealed in the metasomatites of the deposit is close to the intermediate sulfidation type. At the same time, this mineralization, in many of its features, is similar to the mineralization developed in siliceous and quartz-alunite lithocaps, which are formed above degassing intrusions. In this setting, HS-type ore-bearing fluids either are not formed in the system or do not reach epithermal depths.

  2. Growth of low-defect-density nonpolar a-plane GaN on r-plane sapphire using pulse NH3 interrupted etching.

    PubMed

    Son, Ji-Su; Honda, Yoshio; Amano, Hiroshi

    2014-02-10

    Nonpolar a-plane (11-20) GaN (a-GaN) layers with low overall defect density and high crystalline quality were grown on r-plane sapphire substrates using etched a-GaN. The a-GaN layer was etched by pulse NH3 interrupted etching. Subsequently, a 2-µm-thick Si-doped a-GaN layer was regrown on the etched a-GaN layer. A fully coalescent n-type a-GaN layer with a low threading dislocation density (~7.5 × 10(8) cm(-2)) and a low basal stacking fault density (~1.8 × 10(5) cm(-1)) was obtained. Compared with a planar sample, the full width at half maximum of the (11-20) X-ray rocking curve was significantly decreased to 518 arcsec along the c-axis direction and 562 arcsec along the m-axis direction.

  3. Takotsubo (Stress) Cardiomyopathy

    MedlinePlus

    ... Circulation . 2005 ; 111 : 472 – 479 . OpenUrl Abstract / FREE Full Text Wittstein IS , Thiemann DR , Lima JA , Baughman KL , ... syndromes . Circulation . 2008 ; 118 : 397 – 409 . OpenUrl FREE Full Text Sharkey SW , Lesser JR , Maron MS , Maron BJ . ...

  4. Total proctocolectomy and ileal - anal pouch

    MedlinePlus

    Restorative proctocolectomy; Ileal-anal resection; Ileal-anal pouch; J-pouch; S-pouch; Pelvic pouch; Ileal-anal pouch; Ileal ... RD, Mahmoud N, Maron DJ, Ross HM, Rombeau J. Colon and rectum. In: Townsend CM, Beauchamp RD, ...

  5. Many People with Implantable Defibrillators Can Participate in Vigorous Sports

    MedlinePlus

    ... M.D.; Barry J. Maron, M.D.; Frank Marcus, M.D.; Melvin Scheinman, M.D.; Bruce L. ... primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and ...

  6. Structural Anisotropy and Optical Properties of Nonpolar a-Plane GaN Epitaxial Layers.

    PubMed

    Seo, Yong Gon; Shin, Sun Hye; Kim, Doo Soo; Yoon, Hyung-Do; Hwang, Sung-Min; Baik, Kwang Hyeon

    2015-10-01

    In-plane structural anisotropy is characteristic of nonpolar (1120) a-plane GaN (a-GaN) films grown on r-plane sapphire substrates. The anisotropic peak broadenings of X-ray rocking curves (XRCs) are clearly observed with M- or W-shaped dependence on the azimuth angles. We investigated the optical properties of both M- and W-shaped a-GaN samples with room and low-temperature photoluminescence (PL) measurements. The W-shaped a-GaN film showed higher PL intensity and more compressive strain compared to the M-shaped a-GaN film, whereas the XRC peak widths of the M-shaped a-GaN film on the azimuth angles are lower than those of W-shaped specimens, indicating that better crystalline quality was obtained. We speculate that the PL intensity and strain state of a-GaN layers may be more influenced by the crystallinity of a specific crystal orientation or direction, especially along the m-axis as opposed to the c-axis. This occurrence is most likely due to anisotropic defect distributions, resulting from differences in dangling bond densities of (0001) and {1-100} facets.

  7. PIALA 2004: Maron In Read Im Jeje Ej Ad Kojatdikdik, Library Ko Rej Jikin Kakurmool Kojatdikdik In Im Jolet Eo Ad Ej Bwinnid--Literacy Our Hope, Libraries Our Scope and Heritage Our Property (14th, Majuro Atoll, Marshall Islands, November 16-19, 2004) and PIALA 2005: Kasrpacsr Misenge Ac Etwack Lutu--Resources Today and Learning Tomorrow (15th, Tofol, Kosrae, Federated States of Micronesia, November 8-10, 2005). Selected Papers from the Pacific Islands Association of Libraries and Archives Annual Conferences

    ERIC Educational Resources Information Center

    Cohen, Arlene, Ed.

    2006-01-01

    This publication follows the tradition of publishing selected papers from PIALA annual conferences, however, for the first time, two PIALA conferences (PIALA 2004 and PIALA 2005) are published in one volume, containing papers from both events. Both conferences featured papers by local Micronesian and Pacific Islands experts, as well as presenters…

  8. Thermostable alpha-galactosidase from Bacillus stearothermophilus NUB3621: cloning, sequencing and characterization.

    PubMed

    Fridjonsson, O; Watzlawick, H; Gehweiler, A; Mattes, R

    1999-07-01

    An alpha-galactosidase gene from the thermophilic bacterium Bacillus stearothermophilus NUB3621 was cloned, sequenced, expressed in Escherichia coli and the recombinant protein was purified. The Bacillus enzyme, designated AgaN, is similar to alpha-galactosidases of family 36 in the classification of glycosyl hydrolases. The enzyme was estimated to be a tetramer with a molecular mass of subunits 80.3 kDa. The purified AgaN is thermostable and has a temperature optimum of activity at 75 degrees C and a half-life of inactivation of 19 h at 70 degrees C. AgaN displays high affinity for oligomeric substrates such as melibiose and raffinose and is able to hydrolyze raffinose in the presence of 60% sucrose with high efficiency.

  9. Properties of amorphous GaN from first-principles simulations

    NASA Astrophysics Data System (ADS)

    Cai, B.; Drabold, D. A.

    2011-08-01

    Amorphous GaN (a-GaN) models are obtained from first-principles simulations. We compare four a-GaN models generated by “melt-and-quench” and the computer alchemy method. We find that most atoms tend to be fourfold, and a chemically ordered continuous random network is the ideal structure for a-GaN albeit with some coordination defects. Where the electronic structure is concerned, the gap is predicted to be less than 1.0 eV, underestimated as usual by a density functional calculation. We observe a highly localized valence tail and a remarkably delocalized exponential conduction tail in all models generated. Based upon these results, we speculate on potential differences in n- and p-type doping. The structural origin of tail and defect states is discussed. The vibrational density of states and dielectric function are computed and seem consistent with experiment.

  10. 75 FR 44246 - Petition For Rulemaking to Establish Procedures For The Creation and Amendment of Endangered...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-28

    ...: Notice. SUMMARY: EPA is announcing the availability of a January 19, 2010 petition from Dow AgroSciences LLC (``DAS''), Makhteshim Agan of North America, Inc. (``MANA''), and Cheminova, Inc. USA (``Cheminova.... What Action is the Agency Taking? EPA is announcing availability of a petition from Dow...

  11. Self-assembled growth and structural analysis of inclined GaN nanorods on nanoimprinted m-sapphire using catalyst-free metal-organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lee, Kyuseung; Chae, Sooryong; Jang, Jongjin; Min, Daehong; Kim, Jaehwan; Nam, Okhyun

    2016-04-01

    In this study, self-assembled inclined (1-10-3)-oriented GaN nanorods (NRs) were grown on nanoimprinted (10-10) m-sapphire substrates using catalyst-free metal-organic chemical vapor deposition. According to X-ray phi-scans, the inclined GaN NRs were tilted at an angle of ˜57.5° to the [10-10]sapp direction. Specifically, the GaN NRs grew in a single inclined direction to the [11-20]sapp. Uni-directionally inclined NRs were formed through the one-sided (10-11)-faceted growth of the interfacial a-GaN plane layer. It was confirmed that a thin layer of a-GaN was formed on r-facet nanogrooves of the m-sapphire substrate by nitridation. The interfacial a-GaN nucleation affected both the inclined angle and the growth direction of the inclined GaN NRs. Using X-ray diffraction and selective area electron diffraction, the epitaxial relationship between the inclined (1-10-3) GaN NRs and interfacial a-GaN layer on m-sapphire substrates was systematically investigated. Moreover, the inclined GaN NRs were observed to be mostly free of stacking fault-related defects using high-resolution transmission electron microscopy.

  12. 76 FR 77824 - Dicofol; Cancellation Order for Certain Pesticide Registrations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... range of stakeholders including environmental, human health, and agricultural advocates; the chemical industry; pesticide users; and members of the public interested in the sale, distribution, or use of... address 11603 Agan Chemical Manufacturing Ltd, 4515 Falls of Neuse Rd. Suite 300, Raleigh, NC 27609....

  13. Commotio Cordis: Should Physical Educators and Coaches Be Concerned?

    ERIC Educational Resources Information Center

    Berhow, Katie J.; Hansen, Pamela J.; Terbizan, Donna J.

    2012-01-01

    A collapse and cardiac arrest from Commotio Cordis can occur instantaneously from a relatively modest and nonpenetrating blow to the chest in the absence of underlying cardiovascular disease or structural injury to the chest wall or heart itself (Maron, 1998). It is important to note that this collapse could be instantaneous or proceeded by brief…

  14. Enhanced UV detection by non-polar epitaxial GaN films

    SciTech Connect

    Mukundan, Shruti; Chandan, Greeshma; Mohan, Lokesh; Krupanidhi, S. B.; Roul, Basanta; Shetty, Arjun

    2015-12-15

    Nonpolar a-GaN (11-20) epilayers were grown on r-plane (1-102) sapphire substrates using plasma assisted molecular beam epitaxy. High resolution x-ray diffractometer confirmed the orientation of the grown film. Effect of the Ga/N ratio on the morphology and strain of a-GaN epilayers was compared and the best condition was obtained for the nitrogen flow of 1 sccm. Atomic force microscopy was used to analyze the surface morphology while the strain in the film was quantitatively measured using Raman spectroscopy and qualitatively analyzed by reciprocal space mapping technique. UV photo response of a-GaN film was measured after fabricating a metal-semiconductor-metal structure over the film with gold metal. The external quantum efficiency of the photodetectors fabricated in the (0002) polar and (11-20) nonpolar growth directions were compared in terms of responsivity and nonpolar GaN showed the best sensitivity at the cost of comparatively slow response time.

  15. Echocardiographic diagnosis of the different phenotypes of hypertrophic cardiomyopathy.

    PubMed

    Parato, Vito Maurizio; Antoncecchi, Valeria; Sozzi, Fabiola; Marazia, Stefania; Zito, Annapaola; Maiello, Maria; Palmiero, Pasquale

    2016-01-01

    Hypertrophic Cardiomyopathy (HCM) is an inherited cardiovascular disorder of great genetic heterogeneity and has a prevalence of 0.1 - 0.2 % in the general population. Several hundred mutations in more than 27 genes, most of which encode sarcomeric structures, are associated with the HCM phenotype. Then, HCM is an extremely heterogeneous disease and several phenotypes have been described over the years. Originally only two phenotypes were considered, a more common, obstructive type (HOCM, 70 %) and a less common, non-obstructive type (HNCM, 30 %) (Maron BJ, et al. Am J Cardiol 48:418 -28, 1981). Wigle et al. (Circ 92:1680-92, 1995) considered three types of functional phenotypes: subaortic obstruction, midventricular obstruction and cavity obliteration. A leader american working group suggested that HCM should be defined genetically and not morphologically (Maron BJ, et al. Circ 113:1807-16, 2006). The European Society of Cardiology Working Group on Myocardial and Pericardial Diseases recommended otherwise a morphological classification (Elliott P, et al. Eur Heart J 29:270-6, 2008). Echocardiography is still the principal tool for the diagnosis, prognosis and clinical management of HCM. It is well known that the echocardiographic picture may have a clinical and prognostic impact. For this reason, in this article, we summarize the state of the art regarding the echocardiographic pattern of the HCM phenotypes and its impact on clinical course and prognosis. PMID:27519172

  16. Cloning, sequencing, and expression of the gene encoding the Clostridium stercorarium alpha-galactosidase Aga36A in Escherichia coli.

    PubMed

    Suryani; Kimura, Tetsuya; Sakka, Kazuo; Ohmiya, Kunio

    2003-10-01

    The alpha-galactosidase gene aga36A of Clostridium stercorarium F-9 was cloned, sequenced, and expressed in Escherichia coli. The aga36A gene consists of 2,208 nucleotides encoding a protein of 736 amino acids with a predicted molecular weight of 84,786. Aga36A is an enzyme classified in family 36 of the glycoside hydrolases and showed sequence similarity with some enzymes of family 36 such as Geobacillus (formerly Bacillus) stearothermophilus GalA (57%) and AgaN (52%). The enzyme purified from a recombinant E. coli is optimally active at 70 degrees C and pH 6.0. The enzyme hydrolyzed raffinose and guar gum with specific activities of 3.0 U/mg and 0.46 U/mg for the respective substrates.

  17. Nonpolar GaN grown on Si by hydride vapor phase epitaxy using anodized Al nanomask

    NASA Astrophysics Data System (ADS)

    Polyakov, A. Y.; Markov, A. V.; Mezhennyi, M. V.; Govorkov, A. V.; Pavlov, V. F.; Smirnov, N. B.; Donskov, A. A.; D'yakonov, L. I.; Kozlova, Y. P.; Malakhov, S. S.; Yugova, T. G.; Osinsky, V. I.; Gorokh, G. G.; Lyahova, N. N.; Mityukhlyaev, V. B.; Pearton, S. J.

    2009-01-01

    GaN growth by the hydride vapor phase technique on (100) Si substrates masked by porous Al anodic oxide is described. The masks were prepared by vacuum deposition of Al with subsequent anodic oxidation in dilute sorrel acid. The grown GaN layer is nonpolar, with (112¯0) a-orientation and a full width at half maximum of the (112¯0) reflection below 500 arc sec and showing small anisotropy. This result is comparable with the results obtained for a-GaN growth using selective epitaxy or advanced buffer growth routines. Microcathodoluminescence spectra of the grown films confirm a low density of stacking faults. Possible growth mechanisms are discussed.

  18. Electrons and phonons in amorphous semiconductors

    NASA Astrophysics Data System (ADS)

    Prasai, Kiran; Biswas, Parthapratim; Drabold, D. A.

    2016-07-01

    The coupling between lattice vibrations and electrons is one of the central concepts of condensed matter physics. The subject has been deeply studied for crystalline materials, but far less so for amorphous and glassy materials, which are among the most important for applications. In this paper, we explore the electron-lattice coupling using current tools of a first-principles computer simulation. We choose three materials to illustrate the phenomena: amorphous silicon (a-Si), amorphous selenium (a-Se) and amorphous gallium nitride (a-GaN). In each case, we show that there is a strong correlation between the localization of electron states and the magnitude of thermally induced fluctuations in energy eigenvalues obtained from the density-functional theory (i.e. Kohn–Sham eigenvalues). We provide a heuristic theory to explain these observations. The case of a-GaN, a topologically disordered partly ionic insulator, is distinctive compared to the covalent amorphous examples. Next, we explore the consequences of changing the charge state of a system as a proxy for tracking photo-induced structural changes in the materials. Where transport is concerned, we lend insight into the Meyer–Neldel compensation rule and discuss a thermally averaged Kubo–Greenwood formula as a means to estimate electrical conductivity and especially its temperature dependence. We close by showing how the optical gap of an amorphous semiconductor can be computationally engineered with the judicious use of Hellmann–Feynman forces (associated with a few defect states) using molecular dynamics simulations. These forces can be used to close or open an optical gap, and identify a structure with a prescribed gap. We use the approach with plane-wave density functional methods to identify a low-energy amorphous phase of silicon including several coordination defects, yet with a gap close to that of good quality a-Si models.

  19. Electrons and phonons in amorphous semiconductors

    NASA Astrophysics Data System (ADS)

    Prasai, Kiran; Biswas, Parthapratim; Drabold, D. A.

    2016-07-01

    The coupling between lattice vibrations and electrons is one of the central concepts of condensed matter physics. The subject has been deeply studied for crystalline materials, but far less so for amorphous and glassy materials, which are among the most important for applications. In this paper, we explore the electron-lattice coupling using current tools of a first-principles computer simulation. We choose three materials to illustrate the phenomena: amorphous silicon (a-Si), amorphous selenium (a-Se) and amorphous gallium nitride (a-GaN). In each case, we show that there is a strong correlation between the localization of electron states and the magnitude of thermally induced fluctuations in energy eigenvalues obtained from the density-functional theory (i.e. Kohn-Sham eigenvalues). We provide a heuristic theory to explain these observations. The case of a-GaN, a topologically disordered partly ionic insulator, is distinctive compared to the covalent amorphous examples. Next, we explore the consequences of changing the charge state of a system as a proxy for tracking photo-induced structural changes in the materials. Where transport is concerned, we lend insight into the Meyer-Neldel compensation rule and discuss a thermally averaged Kubo-Greenwood formula as a means to estimate electrical conductivity and especially its temperature dependence. We close by showing how the optical gap of an amorphous semiconductor can be computationally engineered with the judicious use of Hellmann-Feynman forces (associated with a few defect states) using molecular dynamics simulations. These forces can be used to close or open an optical gap, and identify a structure with a prescribed gap. We use the approach with plane-wave density functional methods to identify a low-energy amorphous phase of silicon including several coordination defects, yet with a gap close to that of good quality a-Si models.

  20. Construction of In-house Databases in a Corporation

    NASA Astrophysics Data System (ADS)

    Tamura, Haruki; Mezaki, Koji

    This paper describes fundamental idea of technical information management in Mitsubishi Heavy Industries, Ltd., and present status of the activities. Then it introduces the background and history of the development, problems and countermeasures against them regarding Mitsubishi Heavy Industries Technical Information Retrieval System (called MARON) which started its service in May, 1985. The system deals with databases which cover information common to the whole company (in-house research and technical reports, holding information of books, journals and so on), and local information held in each business division or department. Anybody from any division can access to these databases through the company-wide network. The in-house interlibrary loan subsystem called Orderentry is available, which supports acquiring operation of original materials.

  1. Earthquake Simulator Finds Tremor Triggers

    SciTech Connect

    Johnson, Paul

    2015-03-27

    Using a novel device that simulates earthquakes in a laboratory setting, a Los Alamos researcher has found that seismic waves-the sounds radiated from earthquakes-can induce earthquake aftershocks, often long after a quake has subsided. The research provides insight into how earthquakes may be triggered and how they recur. Los Alamos researcher Paul Johnson and colleague Chris Marone at Penn State have discovered how wave energy can be stored in certain types of granular materials-like the type found along certain fault lines across the globe-and how this stored energy can suddenly be released as an earthquake when hit by relatively small seismic waves far beyond the traditional “aftershock zone” of a main quake. Perhaps most surprising, researchers have found that the release of energy can occur minutes, hours, or even days after the sound waves pass; the cause of the delay remains a tantalizing mystery.

  2. Analysis of Hexanitrostilbene (HNS) and Dipicryethane (DPE) for Mutagenicity by the Ames/Salmonella Assay

    SciTech Connect

    Wu, R; Felton, J

    2007-10-12

    The Ames/Salmonella assay, developed by Professor Bruce Ames at the University of California, Berkeley, is a rapid and sensitive assay for detecting mutagenicity of various chemical compounds (Maron and Ames, 1983). It is a widely accepted short-term assay for detecting chemicals that induce mutations in the histidine (his) gene of Salmonella typhimurium. This is a reverse mutation assay that detects the mutational reversion of his-dependent Salmonella to the his-independent counterpart. Thereby, mutagenic compounds will increase the frequency of occurrence of his-independent bacterial colonies. The assay utilizes the specific genetically constructed strains of bacteria either with or without mammalian metabolic activation enzymes (S9), Aroclor induced rat liver homogenate to assess the mutagenicity of different compounds. In this study, we will use the Ames/Salmonella assay to investigate the mutagenicity of Hexanitrostilbene (HNS) from both Bofors and Pantex, and Dipicryethane (DPE).

  3. A microphysical interpretation of the rate-and-state friction direct effect: implications for the seismic cycle

    NASA Astrophysics Data System (ADS)

    van den Ende, Martijn; Niemeijer, André; Spiers, Christopher

    2015-04-01

    For many years, empirical rate-and-state friction laws have been successfully applied to describe the transient frictional behaviour of fault zones, as observed in laboratory experiments and in nature. However, the rate-and-state friction parameters and equations are still poorly understood in terms of the underlying processes that operate at a micro-scale. In addition, there exist large discrepancies between lab-derived values and estimated values for natural fault zones. Because of these discrepancies, extrapolation of the frictional behaviour from sample-scale to the spatial and temporal scales of natural faults is non-trivial. Most notably, there is only a small theoretical basis for the near-instantaneous increase in friction after a sudden increase in sliding velocity (known as the direct effect). Marone et al. (1990) observed a positive relationship between the direct effect and dilatation in quartz gouges. However, the magnitude of the dilatation was significantly higher than expected based on the change in friction, which they explained by non-coaxial dilatation. In more recent years, Beeler et al. (2007) used a normalisation scheme to show that in the case of phyllosilicates, the magnitude of the direct effect is comparable to the stress required for dislocation glide. However, dislocation glide does not explain a-values for "hard" minerals such as quartz and calcite, especially when fluid-rock interactions are rapid. To address these issues, room temperature velocity stepping experiments have been conducted on granular calcite, and granular rock salt as an analogue for quartz under hydrothermal conditions. These experiments clearly demonstrate that the magnitude of the direct effect is much larger in gouges where pressure solution rates are high and deformation is distributed. A large contribution of dilatation to the magnitude of the direct effect becomes apparent in these gouges. In contrast, calcite gouges in which pressure solution is slow, show a

  4. Improved quality non-polar III-nitride heteroepitaxial films and devices

    NASA Astrophysics Data System (ADS)

    Imer, Bilge

    direct comparison, GaN/Al0.15GaN 360 nm UV LEDs were grown on co-loaded planar a-GaN, planar c-GaN and SLEO a-GaN templates. Devices grown on nonpolar SLEO films demonstrated ˜2-3x higher electron mobility, ˜3x lower series resistance, and ˜100-300x higher EQE when compared with the planar nonpolar films.

  5. Anisotropic strain relaxation and the resulting degree of polarization by one- and two-step growth in nonpolar a-plane GaN grown on r-sapphire substrate

    SciTech Connect

    Feng, Shih-Wei Chen, Yu-Yu; Lai, Chih-Ming; Tu, Li-Wei; Han, Jung

    2013-12-21

    Anisotropic strain relaxation and the resulting degree of polarization of the electronic transition in nonpolar a-plane GaN using one- and two-step growth are studied. By using two-step growth, a slower coalescence and a longer roughening-recovery process lead to larger anisotropic strain relaxation, a less striated surface, and lower densities of basal stacking fault (BSF) and prismatic stacking fault (PSF). It is suggested that anisotropic in-plane strains, surface striation, and BSF and PSF densities in nonpolar a-GaN are consequences of the rate of coalescence, the period of roughening-recovery process, and the degree of anisotropic strain relaxation. In addition, the two-step growth mode can enhance the degree of polarization of the electronic transition. The simulation results of the k⋅p perturbation approach show that the oscillator strength and degree of polarization of the electronic transition strongly depend on the in-plane strains upon anisotropic in-plane strain relaxation. The research results provide important information for optimized growth of nonpolar III-nitrides. By using two-step growth and by fabricating the devices on the high-quality nonpolar free-standing GaN substrates, high-efficiency nonpolar a-plane InGaN LEDs can be realized. Nonpolar a-plane InGaN/GaN LEDs can exhibit a strongly polarized light to improve the contrast, glare, eye discomfort and eye strain, and efficiency in display application.

  6. Defect reduction in (112_O) a-plane GaN by two-stage epitaxiallateral overgrowth

    SciTech Connect

    Ni, X.; Ozgur, U.; Fu, Y.; Biyikli, N.; Xie, J.; Baski, A.A.; Morkoc, H.; Liliental-Weber, Z.

    2006-10-20

    In the epitaxial lateral overgrowth (ELO) of (11{bar 2}0) a-plane GaN, the uneven growth rates of two opposing wings, Ga- and N-wings, makes the coalescence of two neighboring wings more difficult than that in c-plane GaN. We report a two-stage growth method to get uniformly coalesced epitaxial lateral overgrown a-plane GaN using metalorganic chemical vapor deposition (MOCVD) by employing relatively lower growth temperature in the first step followed by enhanced lateral growth in the second. Using this method, the height differences between Ga-polar and N-polar wings at the coalescence front could be reduced, thereby making the coalescence of two wings much easier. Transmission electron microscopy (TEM) showed that the threading dislocation density in the wing areas was 1.0x10{sup 8}cm{sup -2}, more than two orders of magnitude lower than that in the window areas (4.2x10{sup 10}cm{sup -2}). However, high density of basal stacking faults of 1.2x104 cm-1 was still observed in the wing areas as compared to c-plane GaN. Atomic force microscopy and photoluminescence measurements on the coalesced ELO a-GaN sample also indicated improved material quality.

  7. Osteosarcomas among beagles exposed to /sup 239/Plutonium. Technical report No. 34

    SciTech Connect

    Whittemore, A S; McMillan, A

    1980-03-01

    A Weibull distribution was fit to the osteosarcoma death times of beagles given single intravenous injections of /sup 239/Pu. For injected doses in the range 0 to 1 ..mu..Ci/kg the osteosarcoma incidence rate h(t) at t days after injection can be fit by a quadratic function of the injected dose. The best fitting linear function was rejected by the data (p < 0.001). A different formula for h(t), derived from amultistage theory for osteosarcoma induction, was also fit to these data. For this purpose microdosimetry calculations were used to estimate the dose to the cells at risk in the endosteal layer (endosteal dose). According to the best fit, h(t) is a quadratic function of endosteal dose at low doses. A linear dose-response relationship was agan rejected. The absence of a linear component at low doses might be explained by the fact that 108 of the 185 animals injected at the lowest doses (< 0.02 ..mu..Ci/kg) were still alive at the time these data were collected.

  8. Stability of stagnation via an expanding accretion shock wave

    NASA Astrophysics Data System (ADS)

    Velikovich, A. L.; Murakami, M.; Taylor, B. D.; Giuliani, J. L.; Zalesak, S. T.; Iwamoto, Y.

    2016-05-01

    Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion shock wave is ubiquitous in inertial confinement fusion (ICF) and high-energy-density plasma physics, the examples ranging from plasma flows in x-ray-generating Z pinches [Maron et al., Phys. Rev. Lett. 111, 035001 (2013)] to the experiments in support of the recently suggested concept of impact ignition in ICF [Azechi et al., Phys. Rev. Lett. 102, 235002 (2009); Murakami et al., Nucl. Fusion 54, 054007 (2014)]. Some experimental evidence indicates that stagnation via an expanding shock wave is stable, but its stability has never been studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction wave behind the expanding shock front and is described by the classic ideal-gas Noh solution in spherical and cylindrical geometry. In either case, the stagnated flow has been demonstrated to be stable, initial perturbations exhibiting a power-law, oscillatory or monotonic, decay with time for all the eigenmodes. This conclusion has been supported by our simulations done both on a Cartesian grid and on a curvilinear grid in spherical coordinates. Dispersion equation determining the eigenvalues of the problem and explicit formulas for the eigenfunction profiles corresponding to these eigenvalues are presented, making it possible to use the theory for hydrocode verification in two and three dimensions.

  9. The dynamic motion of pseudo-sputum mucin solution on a vibrating plate.

    PubMed

    Tarao, Norio; Takagi, Osamu

    2008-01-01

    The motion of pseudo-sputum (20% solution of mucin) on a vibrating plate has been investigated using a function generator and an amplifier. Many finger-like liquid columns have appeared at appropriate frequencies (100-130 Hz) from a droplet of the solution on a vibrating plate. The viscosity of the mucin solution was measured using a capillary viscometer of the Maron-Krieger-Sisko type, and it was shown that the shear-thinning viscosity occurred in the lower frequency region contrary to the fact that the most abnormal viscosity of the rheological dilatancy fluid emerges in higher frequency than the frequency in which it behaves the normal one; the most important mechanical cause of this soliton-like phenomenon or the emergence of finger-like column and wrinkles on the surface of fluid is thought to be the rheological dilatancy (shear-thickening viscosity) of source liquid. In connection with this vibrating liquid column phenomenon, the spectrums of productive cough were also investigated, and it was proved that the effective low frequency vibration, which is a characteristic spectrum of productive cough, is essential for the expectoration and is a similar mechanism to the above-mentioned pug mechanism of the finger-like liquid columns seen on the vibrating plate. PMID:18367821

  10. Transovarial Effect of Novaluron on Tribolium castaneum (Coleoptera: Tenebrionidae) After Termination of Direct Contact.

    PubMed

    Trostanetsky, A; Kostyukovsky, M; Quinn, E

    2015-01-01

    The insect growth regulator novaluron (Rimon 10 EC, Makhteshim-Agan Ltd, Israel) is used against many field pests on corn, vegetables, orchards, forests, and cotton plantations. Previously, we studied various effects of novaluron on stored grain pests. Termination in Tribolium castaneum (Herbst) eggs hatching after treating adults with novaluron and following restoration after adult transfer to untreated media was observed. The objective of this study was to investigate the restoration of T. castaneum egg hatch following transfer of adults from treated media to untreated favorable and unfavorable media. The time needed for hatching restoration of 50% of eggs laid by adults transferred from novaluron (1 ppm) treated flour to untreated flour (RT50) was 2.7 d. RT50 for those transferred to untreated wheat grain was 4.1 d. RT90 in flour was 3.6 d, in grain--6.1 d. Varieties of RTs in grain and in flour with nonoverlapping confidence intervals indicate that RTs were significantly different. Delay of eggs hatching restoration for adults transferred from treated flour to unfavorable media (Petri dishes with limited amount of flour, lying of eggs not detected) was observed. RT50 in flour was 2.1 d and RT90--3.1 d, while RT50 in the unfavorable media was 3.4 d and RT90 6.5 d. Delayed effect of egg hatching restoration after adult transfer to unfavorable media provides evidence of the significant role of insect physiological state in novaluron excretion and (or) degradation by T. castaneum females.

  11. Transovarial Effect of Novaluron on Tribolium castaneum (Coleoptera: Tenebrionidae) After Termination of Direct Contact

    PubMed Central

    Trostanetsky, A.; Kostyukovsky, M.; Quinn, E.

    2015-01-01

    The insect growth regulator novaluron (Rimon 10 EC, Makhteshim-Agan Ltd, Israel) is used against many field pests on corn, vegetables, orchards, forests, and cotton plantations. Previously, we studied various effects of novaluron on stored grain pests. Termination in Tribolium castaneum (Herbst) eggs hatching after treating adults with novaluron and following restoration after adult transfer to untreated media was observed. The objective of this study was to investigate the restoration of T. castaneum egg hatch following transfer of adults from treated media to untreated favorable and unfavorable media. The time needed for hatching restoration of 50% of eggs laid by adults transferred from novaluron (1 ppm) treated flour to untreated flour (RT50) was 2.7 d. RT50 for those transferred to untreated wheat grain was 4.1 d. RT90 in flour was 3.6 d, in grain—6.1 d. Varieties of RTs in grain and in flour with nonoverlapping confidence intervals indicate that RTs were significantly different. Delay of eggs hatching restoration for adults transferred from treated flour to unfavorable media (Petri dishes with limited amount of flour, lying of eggs not detected) was observed. RT50 in flour was 2.1 d and RT90—3.1 d, while RT50 in the unfavorable media was 3.4 d and RT90 6.5 d. Delayed effect of egg hatching restoration after adult transfer to unfavorable media provides evidence of the significant role of insect physiological state in novaluron excretion and (or) degradation by T. castaneum females. PMID:26363061

  12. Up-regulation of the mammalian target of rapamycin complex 1 subunit Raptor by aldosterone induces abnormal pulmonary artery smooth muscle cell survival patterns to promote pulmonary arterial hypertension.

    PubMed

    Aghamohammadzadeh, Reza; Zhang, Ying-Yi; Stephens, Thomas E; Arons, Elena; Zaman, Paula; Polach, Kevin J; Matar, Majed; Yung, Lai-Ming; Yu, Paul B; Bowman, Frederick P; Opotowsky, Alexander R; Waxman, Aaron B; Loscalzo, Joseph; Leopold, Jane A; Maron, Bradley A

    2016-07-01

    Activation of the mammalian target of rapamycin complex 1 (mTORC1) subunit Raptor induces cell growth and is a downstream target of Akt. Elevated levels of aldosterone activate Akt, and, in pulmonary arterial hypertension (PAH), correlate with pulmonary arteriole thickening, which suggests that mTORC1 regulation by aldosterone may mediate adverse pulmonary vascular remodeling. We hypothesized that aldosterone-Raptor signaling induces abnormal pulmonary artery smooth muscle cell (PASMC) survival patterns to promote PAH. Remodeled pulmonary arterioles from SU-5416/hypoxia-PAH rats and monocrotaline-PAH rats with hyperaldosteronism expressed increased levels of the Raptor target, p70S6K, which provided a basis for investigating aldosterone-Raptor signaling in human PASMCs. Aldosterone (10(-9) to 10(-7) M) increased Akt/mTOR/Raptor to activate p70S6K and increase proliferation, viability, and apoptosis resistance in PASMCs. In PASMCs transfected with Raptor-small interfering RNA or treated with spironolactone/eplerenone, aldosterone or pulmonary arterial plasma from patients with PAH failed to increase p70S6K activation or to induce cell survival in vitro Optimal inhibition of pulmonary arteriole Raptor was achieved by treatment with Staramine-monomethoxy polyethylene glycol that was formulated with Raptor-small interfering RNA plus spironolactone in vivo, which decreased arteriole muscularization and pulmonary hypertension in 2 experimental animal models of PAH in vivo Up-regulation of mTORC1 by aldosterone is a critical pathobiologic mechanism that controls PASMC survival to promote hypertrophic vascular remodeling and PAH.-Aghamohammadzadeh, R., Zhang, Y.-Y., Stephens, T. E., Arons, E., Zaman, P., Polach, K. J., Matar, M., Yung, L.-M., Yu, P. B., Bowman, F. P., Opotowsky, A. R., Waxman, A. B., Loscalzo, J., Leopold, J. A., Maron, B. A. Up-regulation of the mammalian target of rapamycin complex 1 subunit Raptor by aldosterone induces abnormal pulmonary artery smooth

  13. Anisotropic Shear-wave Velocity Structure of East Asian Upper Mantle from Waveform Tomography

    NASA Astrophysics Data System (ADS)

    Chong, J.; Yuan, H.; French, S. W.; Romanowicz, B. A.; Ni, S.

    2012-12-01

    East Asia is a seismically active region featuring active tectonic belts, such as the Himalaya collision zone, western Pacific subduction zones and the Tianshan- Baikal tectonic belt. In this study, we applied full waveform time domain tomography to image 3D isotropic, radially and azimuthally anisotropic upper mantle shear velocity structure of East Asia. High quality teleseismic waveforms were collected for both permanent and temporary stations in the target and its adjacent regions, providing good ray path coverage of the study region. Fundamental and overtone wave packets, filtered down to 60 sec, were inverted for isotropic and radially anisotropic shear wave structure using normal mode asymptotic coupling theory (NACT: Li and Romanowicz, 1995). Joint inversion of SKS measurements and seismic waveforms was then carried out following the methodology described in (Marone and Romanowicz, 2007). The 3D velocity model shows strong lateral heterogeneities in the target region, which correlate well with the surface geology in East Asia. Our model shows that Indian lithosphere has subducted beneath Tibet with a different northern reach from western to eastern Tibet,. We also find variations of the slab geometry in Western Pacific subduction zones. Old and stable regions, such as, Indian shield, Siberia platform, Tarim and Yangtze blocks are found to have higher shear wave velocity in the upper mantle. Lower velocity anomalies are found in regions like Baikal rift, Tienshan, Indochina block, and the regions along Japan island-Ryukyu Trench and Izu-bonin Trench. The dominant fast and slow velocity boundaries in the study region are well correlated with tectonic belts, such as the central Asian orogenic belt and Alty/Qilian-Qinling/Dabie orogenic belt. Our radially anisotropic model shows Vsh> Vsv in oceanic regions and at larger depths(>300km), and Vsv > Vsh in some orogenic zones.. We'll show preliminary results of azimuthally anisotropic joint inversion of SKS

  14. The intravenous laser blood irradiation in chronic pain and fibromyalgia.

    PubMed

    Momenzadeh, Sirous; Abbasi, Mohammadzaki; Ebadifar, Asghar; Aryani, Mohammadreza; Bayrami, Jafar; Nematollahi, Fatemeh

    2015-01-01

    Intravenous laser blood irradiation was first introduced into therapy by the Soviet scientists EN.Meschalkin and VS.Sergiewski in 1981. Originally this method was developed for the treatment of cardiovascular diseases. Improvement of rheologic properties of the blood as well as improvement of microcirculation and reduction of the area of infarction has been proved. Further, reduction of dysrhythmia and sudden cardiac death was achieved. At first, only the Helium-Neon laser (632.8 nm) was used in this therapy. For that, a power of 1-3mW and a period of exposure of 20-60 minutes were applied. The treatments were carried out once or twice a day up to ten appointments in all1. In the years after, many, and for the most part Russian studies showed that helium-neon laser had various effects on many organs and on the hematologic and immunologic system. The studies were published mainly in Russian which were little known in the West because of decades of political separation, and were regarded with disapproval. Besides clinical research and application for patients, the cell biological basis was developed by the Estonian cell biologist Tiina Karu at the same time. An abstract is to be found in her work "The Science of Low-Power Laser-Therapy" PMID:25699161

  15. The Intravenous Laser Blood Irradiation in Chronic Pain and Fibromyalgia

    PubMed Central

    Momenzadeh, Sirous; Abbasi, Mohammadzaki; Ebadifar, Asghar; Aryani, Mohammadreza; Bayrami, Jafar; Nematollahi, Fatemeh

    2015-01-01

    Intravenous laser blood irradiation was first introduced into therapy by the Soviet scientists EN.Meschalkin and VS.Sergiewski in 1981. Originally this method was developed for the treatment of cardiovascular diseases. Improvement of rheologic properties of the blood as well as improvement of microcirculation and reduction of the area of infarction has been proved. Further, reduction of dysrhythmia and sudden cardiac death was achieved. At first, only the Helium-Neon laser (632.8 nm) was used in this therapy. For that, a power of 1-3mW and a period of exposure of 20-60 minutes were applied. The treatments were carried out once or twice a day up to ten appointments in all1. In the years after, many, and for the most part Russian studies showed that helium-neon laser had various effects on many organs and on the hematologic and immunologic system. The studies were published mainly in Russian which were little known in the West because of decades of political separation, and were regarded with disapproval. Besides clinical research and application for patients, the cell biological basis was developed by the Estonian cell biologist Tiina Karu at the same time. An abstract is to be found in her work "The Science of Low-Power Laser-Therapy" PMID:25699161

  16. Physics of friction and strain rate localization in synthetic fault gouge

    NASA Astrophysics Data System (ADS)

    Sleep, Norman H.; Richardson, Eliza; Marone, Chris

    2000-11-01

    Data on synthetic fault gouge previously collected by Richardson and Marone [1999] were compared with the predictions of a unified theory for rate- and state-dependent friction compiled by Sleep [1997]. The theory treats the gouge as a continuum one-dimensional fluid sheared between parallel plates. It is predicted that the strain rate localized into a shear band of width called Wss during steady state sliding from the nominal width of the gouge zone Wnom. The critical displacement during velocity stepping tests is predicted to be Wss ɛint, where ɛint is the critical strain, an intrinsic material property. It is predicted that the strain rate for renewed sliding after holds delocalizes to a width Wnew which is greater than Wss and for long holds approaches the full gouge zone width Wnom. The displacement for recovery of the shear traction to its steady state value is predicted to be Wnewɛint, which for long holds is much greater than the critical displacement obtained by velocity stepping. Only the macroscopic effects of this process could be studied using the laboratory data in hand. Compaction during the hold and the difference between peak shear traction upon restart and the steady state shear traction during sliding (healing) were measured. To simulate more complex normal traction variations on real faults, the normal traction was varied sinusoidally about its previous value during some holds. The theory reasonably predicts the observed relationship between healing and compaction and healing versus hold time. It predicts the slip needed for recovery of shear traction following holds but poorly predicts the shear traction versus time during recovery. We attribute this failure to the fact that the laboratory gouge is a heterogeneous three-dimensional substance. Qualitatively, the delocalized width Wnew varies with position within the gouge plane, and slip is required for localized shear to organize in three dimensions. As strain rate was not observed as a

  17. Dry and Wet Friction of Plagioclase: Pure Cataclastic Flow(CF) vs. CF with Concurrent Pressure Solution

    NASA Astrophysics Data System (ADS)

    He, C.; Tan, W.

    2015-12-01

    To distinguish different deformation mechanisms at hydrothermal conditions, friction experiments of plagioclase under nominally dry conditions were compared with that at hydrothermal conditions documented in a previous study[He et al.,2013]. Preliminary result[Tan and He, 2008] shows that the rate dependence of plagioclase under confining pressure of 150MPa and nominally dry conditions is velocity strengthening at temperatures of 50-600oC, in contrast to the full velocity weakening at hydrothermal conditions. Here a) we conducted data fitting to the rate and state friction law to compare with the hydrothermal case; b) microstructural comparison was performed to understand the difference between the dry and wet conditions in the operative deformation mechanisms. The evolution effect (b value) under dry conditions exhibits much smaller values than that at wet conditions, and in contrast to the increasing trend at wet conditions, b values under dry conditions have a decreasing trend as temperature increases, from ~0.007 at 300oC down to 0 at 600oC. The direct effect (a value) at dry conditions has a peak of ~0.01 at 300oC and decreases to a level of 0.007-0.008 at higher temperatures, in contrast to the increasing trend seen at hydrothermal conditions. In the dry case, microstructure at temperatures of 300-600oC transitions gradually from a fabric characterized by localized Riedel shear zones to pervasive shear deformation, with the grain size reduced to a level of 1-3 micron in a submicron matrix in the latter case, corresponding to a lower porosity. The close association between porosity evolution and that of state variable revealed in previous studies[Morrow and Byerlee, 1989; Marone et al.,1990] suggests that the porosity change contributes largely to the evolution effect in addition to plasticity at intergranular contacts, probably due to gradual switching between different densities of packing. Our dry experiments indicate a cataclastic flow where the evolution

  18. Delayed triggering of the 2012 Mw 8.6 Wharton Basin earthquake

    NASA Astrophysics Data System (ADS)

    Masuti, S. S.; Barbot, S.

    2014-12-01

    The April 2012 Mw 8.6 Wharton Basin earthquake, followed by a magnitude 8.2 aftershock, is the largest ever instrumentally recorded strike-slip earthquake. The large magnitude event culminated a sustained strike-slip seismic activity in the diffuse boundary between the Indian and Australian plates and it reactivated some fracture zones of the Wharton Basin, previously simple structural discontinuities, into active faults. Previous studies (Delescluse et al., 2012; Wiseman and Burgmann et al., 2012) have shown the importance of the static Coulomb stress change due to the 2004 Mw 9.2 Aceh-Andaman and the 2005 Mw 8.6 Nias earthquakes in the triggering of the 2012 main shock. However, the mechanism responsible for the 7-year delay remains unclear. Here, we investigate the role of viscoelastic relaxation in the oceanic asthenosphere and aseismic slip on the N-S oriented reactivated fracture zones in the Wharton basin to explain the triggering mechanism. The deformation in the oceanic plate transitions from localized frictional sliding in the lithosphere to more distributed flow in the asthenosphere. There, the time-dependent deformation following large stress perturbations may induce significant stress changes at larger distances than coseismically. Similarly, if some fracture zones in the Wharton Basin have been reactivated into active faults, they may serve as efficient stress guides between the Sunda megathrust and the epicentral area of the 2012 event. To test these hypotheses, we use Relax (Barbot & Fialko, 2010), a numerical method that can evaluate coseismic and postseismic stress evolution using a realistic representation of the Sumatra subduction zone geometry and the Wharton Basin fracture zones, and rheological parameters inferred from laboratory experiments. Using typical parameters for power-law flow (Brace & Kohlstedt, 1980) and rate-strengthening friction (Marone et al, 1991), we infer the changes in confining pressure, shear stress and Coulomb stress

  19. Constraining friction laws by experimental observations and numerical simulations of various rupture modes

    NASA Astrophysics Data System (ADS)

    Lu, X.; Lapusta, N.; Rosakis, A. J.

    2006-12-01

    builds on our earlier effort to model transition from sub-Rayleigh to supershear rupture speeds observed in earlier experiments (Xia et al., 2004), which can be done with both slip-dependent and rate-dependent friction laws. To make a meaningful comparison between simulations and experiments, we plan to quantify independently as many input parameters as possible, including loading parameters and frictional properties of Homalite interfaces. One of the challenges is to produce samples with repeatable interface roughness. Quantifying frictional properties of Homalite at a wide range of sliding speeds is a collaboration with N. Beeler and B. Kilgore (USGS), C. Marone (Penn State), and G. Ravichandran (Caltech).

  20. 2D Simulations of Earthquake Cycles at a Subduction Zone Based on a Rate and State Friction Law -Effects of Pore Fluid Pressure Changes-

    NASA Astrophysics Data System (ADS)

    Mitsui, Y.; Hirahara, K.

    2006-12-01

    There have been a lot of studies that simulate large earthquakes occurring quasi-periodically at a subduction zone, based on the laboratory-derived rate-and-state friction law [eg. Kato and Hirasawa (1997), Hirose and Hirahara (2002)]. All of them assume that pore fluid pressure in the fault zone is constant. However, in the fault zone, pore fluid pressure changes suddenly, due to coseismic pore dilatation [Marone (1990)] and thermal pressurization [Mase and Smith (1987)]. If pore fluid pressure drops and effective normal stress rises, fault slip is decelerated. Inversely, if pore fluid pressure rises and effective normal stress drops, fault slip is accelerated. The effect of pore fluid may cause slow slip events and low-frequency tremor [Kodaira et al. (2004), Shelly et al. (2006)]. For a simple spring model, how pore dilatation affects slip instability was investigated [Segall and Rice (1995), Sleep (1995)]. When the rate of the slip becomes high, pore dilatation occurs and pore pressure drops, and the rate of the slip is restrained. Then the inflow of pore fluid recovers the pore pressure. We execute 2D earthquake cycle simulations at a subduction zone, taking into account such changes of pore fluid pressure following Segall and Rice (1995), in addition to the numerical scheme in Kato and Hirasawa (1997). We do not adopt hydrostatic pore pressure but excess pore pressure for initial condition, because upflow of dehydrated water seems to exist at a subduction zone. In our model, pore fluid is confined to the fault damage zone and flows along the plate interface. The smaller the flow rate is, the later pore pressure recovers. Since effective normal stress keeps larger, the fault slip is decelerated and stress drop becomes smaller. Therefore the smaller flow rate along the fault zone leads to the shorter earthquake recurrence time. Thus, not only the frictional parameters and the subduction rate but also the fault zone permeability affects the recurrence time of

  1. The Effect of Fracture Filler Composition on the Parameters of Shear Deformation Regime

    NASA Astrophysics Data System (ADS)

    Pavlov, D.; Ostapchuk, A.; Batuhtin, I.

    2015-12-01

    RFBR (grant no. 13-05-00780). 1. Mair, K., K. M. Frye, and C. Marone (2002), J.Geophys.Res., 107(B10), 2219. 2. G.G. Kocharyan, V.K. Markov, A.A. Ostapchuk, and D.V. Pavlov (2014), Phys.Mes, 17(2), 123-133.

  2. Current Status of the Late Triassic and Early Jurassic APTS from Continental Sediments and Correlation with Standard Marine Stages

    NASA Astrophysics Data System (ADS)

    Kent, D. V.; Olsen, P. E.; Muttoni, G.

    2014-12-01

    A reproducible geomagnetic polarity template for the Late Triassic and earliest Jurassic continues to be that determined from ~5,000 meters of cored section in the Newark basin and ~2,500 meters of outcrop section in the Hartford basin, sampled at nominal ~20 kyr intervals according to a well-developed climate cyclicity that characterizes the lacustrine strata present in all but the fluviatile portions of the basins [Kent & Olsen, 1999, 2008 JGR]. The age model is based on the 405 kyr Milankovich climate cycle and pegging the sequence to high precision U-Pb dating of the Central Atlantic Magmatic Province (CAMP) at 201.6 to 200.9 Ma [Blackburn+2013 Science], the initiation of which is practically coincident with the end-Triassic extinction level (formerly set to 202 Ma) and within a climatic precession cycle after magnetochron E23r. The resulting astrochronostratigraphic polarity time scale (APTS) has 66 Poisson-distributed polarity intervals from chrons E8r (~225 Ma) to H27n (~199 Ma) with a constant sediment-accumulation rate extrapolation to chron E1r (~233 Ma). Magnetostratigraphic correlations from the most complete and usually the thickest Tethyan marine sections suggest that the Carnian/Norian boundary occurs within ~E7n [Channell+2003 PPP; Muttoni+2004 GSAB] at an APTS age of 227.5 Ma and for the Norian/Rhaetian boundary anywhere from E16n [Husing+2011 EPSL] at ~210.5 Ma to E20r [Maron+2014 Geology] at ~205.4 Ma depending on choice of conodont taxa, whereas the Hettangian/Sinemurian boundary can be placed at ~199.5 Ma within the marine equivalent of H25r [Husing+2014 EPSL]. These APTS ages are in substantive agreement with available high-precision dates in marine strata for the late Carnian [231 Ma: Furin+2006 Geology], latest Norian [205.5 Ma: Wotslaw+2014 Geology], and the boundaries of the Triassic/Jurassic [201.3 Ma: Guex+2012 PPP] and the Hettangian/Sinemurian [199.5 Ma: Schaltegger+2008 EPSL]. Carnian magnetostratigraphy needs to be improved but

  3. Scale dependency of fracture energy and estimates thereof via dynamic rupture solutions with strong thermal weakening

    NASA Astrophysics Data System (ADS)

    Viesca, R. C.; Garagash, D.

    2013-12-01

    Seismological estimates of fracture energy show a scaling with the total slip of an earthquake [e.g., Abercrombie and Rice, GJI 2005]. Potential sources for this scale dependency are coseismic fault strength reductions that continue with increasing slip or an increasing amount of off-fault inelastic deformation with dynamic rupture propagation [e.g., Andrews, JGR 2005; Rice, JGR 2006]. Here, we investigate the former mechanism by solving for the slip dependence of fracture energy at the crack tip of a dynamically propagating rupture in which weakening takes place by strong reductions of friction via flash heating of asperity contacts and thermal pressurization of pore fluid leading to reductions in effective normal stress. Laboratory measurements of small characteristic slip evolution distances for friction (~10 μm at low slip rates of μm-mm/s, possibly up to 1 mm for slip rates near 0.1 m/s) [e.g., Marone and Kilgore, Nature 1993; Kohli et al., JGR 2011] imply that flash weakening of friction occurs at small slips before any significant thermal pressurization and may thus have a negligible contribution to the total fracture energy [Brantut and Rice, GRL 2011; Garagash, AGU 2011]. The subsequent manner of weakening under thermal pressurization (the dominant contributor to fracture energy) spans a range of behavior from the deformation of a finite-thickness shear zone in which diffusion is negligible (i.e., undrained-adiabatic) to that in which large-scale diffusion obscures the existence of a thin shear zone and thermal pressurization effectively occurs by the heating of slip on a plane. Separating the contribution of flash heating, the dynamic rupture solutions reduce to a problem with a single parameter, which is the ratio of the undrained-adiabatic slip-weakening distance (δc) to the characteristic slip-on-a-plane slip-weakening distance (L*). However, for any value of the parameter, there are two end-member scalings of the fracture energy: for small slip

  4. Bulk-friction modeling of afterslip and the modified Omori law

    USGS Publications Warehouse

    Wennerberg, L.; Sharp, R.V.

    1997-01-01

    Afterslip data from the Superstition Hills fault in southern California, a creep event on the same fault, the modified Omori law, and cumulative moments from aftershocks of the 1957 Aleutian Islands earthquake all indicate that the original formulation by Dieterich (1981) [Constitutive properties of faults with simulated gouge. AGU, Geophys. Monogr. 24, 103-120] for friction evolution is more appropriate for systems far from instability than the commonly used approximation developed by Ruina (1983) [Slip instability and state variable friction laws. J. Geophys. Res. 88, 10359-10370] to study instability. The mathematical framework we use to test the friction models is a one-dimensional, massless spring-slider under the simplifying assumption, proposed by Scholz (1990) [The Mechanics of Earthquakes and Faulting. Cambridge University Press] and used by Marone et al. (1991) [On the mechanics of earthquake afterslip. J. Geophys. Res., 96: 8441-8452], that the state variable takes on its velocity-dependent steady-state value throughout motion in response to a step in stress. This assumption removes explicit state-variable dependence from the model, obviating the need to consider state-variable evolution equations. Anti-derivatives of the modified Omori law fit our data very well and are very good approximate solutions to our model equations. A plausible friction model with Omori-law solutions used by Wesson (1988) [Dynamics of fault creep. J. Geophys. Res. 93, 8929-8951] to model fault creep and generalized by Rice (1983) [Constitutive relations for fault slip and earthquake instabilities. Pure Appl. Geophys. 121, 443-475] to a rate-and-state-variable friction model yields exactly Omori's law with exponents greater than 1, but yields unstable solutions for Omori exponents less than 1. We estimate from the Dieterich formulation the dimensionless parameter a* which is equal to the product of the nominal coefficient of friction and the more commonly reported friction

  5. Dynamic simulation of wavy-stratified two-phase flow with the one-dimensional two-fluid model

    NASA Astrophysics Data System (ADS)

    Fullmer, William D.

    conditions. This appears to result in non-convergence when particular solutions at a specific time are compared using different numerical discretizations. However, it is shown that the chaotic solutions exhibit an invariant spectrum in wavenumber space that can be used to assess the convergence of solutions. This concept is applied to a Kelvin-Helmholtz experiment of kerosene and liquid water in a tilted channel whereby many slightly different simulations are run and averaged to determine the mean behavior. Comparisons to experimental data are favorable; especially considering the limitations of applying a one-dimensional model to a dynamic simulation of wavy channel flow. When the analysis is extended to consider air-water flows, several additional challenges are encountered related to the long-wavelength inviscid Kelvin-Helmholtz instability, which is the instability inherent to the one-dimensional two-fluid model. The transition from stratified to wavy flow is significantly over-predicted, i.e., requires a larger velocity to become unstable than observed experimentally. The wave sheltering model of Brauner and Maron (1993) is included in the interfacial shear model and calibrated for flow in a rectangular channel. However, when the unstable flow regime is simulated a wavy flow pattern does not develop as in the liquid-liquid case. Due to the near absence of inertia in the lighter gas phase, viscosity and surface tension are unable to bound the growth of disturbances within the physical limitations of the channel geometry. Transitions to regions of single phase flow result, indicating a slug flow pattern where wavy flow should exist. A novel approach is taken where the instability mechanism, here the sheltering force, is adjusted based on local geometric conditions, namely the void fraction gradient. Comparison to data shows promising results, although a large degree of uncertainty in such an approach remains due to a lack of local experimental data.

  6. This Experiment Cried Out for a Different Interpretation

    NASA Astrophysics Data System (ADS)

    McSaveney, M. J.; Wang, G.

    2011-12-01

    and fragments of crystal-fragment agglomerates. In section perpendicular to Y-shear surfaces and parallel to shear direction, the cataclastic zone appeared to be a repeating series of R2 Riedel shears between repeating discontinuous Y-shears. Given the deformation required to open R2-shears, it was apparent that Y-shears would be ephemeral under conditions for continuing R2-shear generation. We did not measure the squeal pitch, but felt aural discomfort before any sound was heard. Our experiment cried out to us that weakening can come from microseismic (acoustic) lubrication of the Y-shear interface, from the vibration that resonates to make DPRI-6 squeal. Niemeijer, A; Marone, C; Elsworth, D. 2010. Frictional strength and strain weakening in simulated fault gouge: competition between geometrical weakening and chemical strengthening. J. Geophys. Res. 115, B10207, doi:10.1029/2009JB000838, 2010 Sassa, K.; Fukuoka, H.; Wang, G; Ishikawa, N. 2004. Undrained dynamic-loading ring-shear apparatus and its application to landslide dynamics. Landslides 1: 7-19.

  7. Laboratory Experiments and Theoretical Studies of Rupture Modes and Supershear Transition

    NASA Astrophysics Data System (ADS)

    Lu, X.; Lapusta, N.; Rosakis, A.

    2007-12-01

    speed of pulse-like ruptures is lower. These supershear speeds are consistent with the analytical predictions of the velocity-weakening model of Samudrala et al. (2002). The agreement between our experimental observations and models of velocity-weakening faults suggests that velocity-weakening friction plays an important role in dynamic behavior of ruptures and implies that expressing dynamic weakening of friction solely in terms of slip may not be a sufficiently general description. We will also present our current efforts to further analyze the experiments, including the potential effects of rupture initiation procedure. Our preliminary experimental measurements of vertical motion of points close to the interface indicate that there is no opening of the interface during sliding at locations where we determine the rupture mode, although more analysis is need to determine whether there is any significant normal stress variation. We are in the process of including normal stress variations into our existing numerical code to investigate this issue, as well as to study which friction law is most consistent with the experimental observations. We are also working on quantifying the parameters of the explosion and determining the friction properties of Homalite (collaboration with N. Beeler and B. Kilgore (USGS), C. Marone (Penn State), and G. Ravichandran (Caltech)).

  8. An infrastructure for the integration of geoscience instruments and sensors on the Grid

    NASA Astrophysics Data System (ADS)

    Pugliese, R.; Prica, M.; Kourousias, G.; Del Linz, A.; Curri, A.

    2009-04-01

    ). In this paper i) we define the need for integration of instrumentation in the Grid, ii) we introduce the solution of the Instrument Element, iii) we demonstrate a suitable end-user web portal for accessing Grid resources, iv) we describe from the Grid-technological point of view the process of the integration to the Grid of two advanced environmental monitoring devices. References [1] M. Surridge, S. Taylor, D. De Roure, and E. Zaluska, "Experiences with GRIA—Industrial Applications on a Web Services Grid," e-Science and Grid Computing, First International Conference on e-Science and Grid Computing, 2005, pp. 98-105. [2] A. Chervenak, I. Foster, C. Kesselman, C. Salisbury, and S. Tuecke, "The data grid: Towards an architecture for the distributed management and analysis of large scientific datasets," Journal of Network and Computer Applications, vol. 23, 2000, pp. 187-200. [3] B. Allcock, J. Bester, J. Bresnahan, A.L. Chervenak, I. Foster, C. Kesselman, S. Meder, V. Nefedova, D. Quesnel, and S. Tuecke, "Data management and transfer in high-performance computational grid environments," Parallel Computing, vol. 28, 2002, pp. 749-771. [4] E. Frizziero, M. Gulmini, F. Lelli, G. Maron, A. Oh, S. Orlando, A. Petrucci, S. Squizzato, and S. Traldi, "Instrument Element: A New Grid component that Enables the Control of Remote Instrumentation," Proceedings of the Sixth IEEE International Symposium on Cluster Computing and the Grid (CCGRID'06)-Volume 00, IEEE Computer Society Washington, DC, USA, 2006. [5] R. Ranon, L. De Marco, A. Senerchia, S. Gabrielli, L. Chittaro, R. Pugliese, L. Del Cano, F. Asnicar, and M. Prica, "A Web-based Tool for Collaborative Access to Scientific Instruments in Cyberinfrastructures." 1 The DORII project is supported by the European Commission within the 7th Framework Programme (FP7/2007-2013) under grant agreement no. RI-213110. URL: http://www.dorii.eu 2 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale. URL: http://www.ogs.trieste.it

  9. Along strike applicability of results from the Deep Fault Drilling Project, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Boulton, C. J.; Toy, V. G.; Barth, N. C.; Carpenter, B. M.

    2012-12-01

    similar brown PSZ gouges also occur at localities north and south of Gaunt Creek, from Little Man River to Robinson Creek, an along strike distance of 120 km. Everywhere mapped, brown PSZ gouges form at the contact between Pacific Plate and Australian Plate-derived cataclasites, which, importantly, do not contain smectite. Smectite-bearing gouges are generally absent on shallow dipping dextral-reverse faults at the toes of large thrust sheets, where plate boundary cataclasites overlie Late Quaternary gravels in sharp contact. Our results suggest that PSZ gouges retrieved in the DFDP-1 cores are commonly present on moderately dipping (average orientation 043°/30°SE; Norris and Cooper, 2007) dextral-reverse faults along the central Alpine Fault, and we discuss modes of PSZ formation. References Boulton, C., B.M. Carpenter, V. Toy, and C. Marone (2012). Physical properties of surface outcrop cataclastic fault rocks, Alpine Fault, New Zealand. Geochem. Geophys. Geosyst., 13, doi:10.1029/2011GC003872. Norris, R.J., and A.F. Cooper (2007). The Alpine Fault, New Zealand: Surface Geology and Field Relationships, in A Continental Plate Boundary: Tectonics at South Island, New Zealand, edited by Okaya, D., Stern, T., and F. Davey, American Geophysical Union Monograph Vol 175, Washington, D.C., 159-178.

  10. Improvement of barrier properties of poly(ethylene terephthalate)/organoclay nanocomposites

    NASA Astrophysics Data System (ADS)

    Dini, Maryam

    ( 1H NMR and 13C NMR) spectra showed the linear molecular structure of PET. The effect of organoclay concentration on the rheological, thermal, mechanical and barrier properties of the PET nanocomposites prepared by different methods was studied in the second part of this work. XRD, SEM and TEM analyses displayed intercalated/exfoliated morphology in all PET/C30B nanocomposites, with a higher degree of intercalation and delamination for the water-assisted process. Enhanced mechanical and barrier properties were obtained in PET-C30B nanocomposites compared to the neat PET. The nanocomposites exhibited higher tensile modulus and lower oxygen permeability after SSP. Elongation at break was significantly higher for SSP nanocomposites than for nanocomposites processed by conventional melt mixing. Elongation at break for conventional PET nanocomposites containing 2 wt% C30B was 6%, but for nanocomposites after SSP, the elongation at break was around 145%. Compared to the neat PET, improvements of 45% in tensile modulus and 42% in barrier behavior were found for nanocomposites containing 6 wt% C30B. The pseudo-inclusion model was used to predict the tensile modulus of PET nanocomposites and to determine the effect of intercalation microstructure on the model predictions. Moreover, the Nielsen and Bharadwaj models were employed for the prediction of permeability in the presence of organoclay. Studies of solid-state polymerization of PET and PET nanocomposites with different concentrations of Cloisite 30B and particle size were carried out at different reaction times in the third part of this work. Moreover, the effect of particle size on the rate of SSP was also investigated. Viscometry, titration, rheological and dynamic scanning calorimetry (DSC) measurements were used to analyze the samples from SSP. The weight-averaged molecular weight (MW) of PET was shown to increase significantly following SSP. The Maron-Pierce model was utilized to evaluate the molecular weight of PET